EPA/530-SW-91 -065A
Mining Sites on the National Priorities List
NPL Site Summary Reports
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Volume I
Prepared by :
Science Applications International Coiporation
Environmental and Health Sciences Group
7600-A Lecsburg Pike
Falls Church, Virginia 22043

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Mining Sites on the National Priorities List
NPL Site Summary Reports
TABLE OF CONTENTS
Volume I
Aluminum Company of America (Vancouver Smelter)
Vancouver, WA
Anaconda Smelter
Mill Creek, MT
Atlas Asbestos Mine
Fresno County, CA
Bunker Hill Mining and Metallurgical Complex
Kellog, ID
California Gulch
Leadville, CO
Carson River
Lyon and Churchill Co., NV
Celtor Chemical Works
Humboldt Co., CA
Cherokee County/Galena Subsite
Cherokee Co., KS
Cimarron Mining Corporation
Carizozo, NM
Clear Creek/Central City
Clear Creek, CO
Cleveland Mill
Silver City, NM
1

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Mining Waste NPL Site Summary Report
Aluminum Company of America (Vancouver Smelter)
Vancouver, Washington
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-0025, Work Assignment 20. A
previous draft of this report was reviewed by Robert Keevit of EPA
Region X [(206) 753-9014], the Remedial Project Manager for the
site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
ALUMINUM COMPANY OF AMERICA (VANCOUVER SMELTER)
VANCOUVER, WASHINGTON
INTRODUCTION
This Site Summary Report for the Aluminum Company of America (Vancouver Smelter) is one of a
series of reports on mining sites on the National Priorities List (NPL). The reports have been
prepared to support EPA's mining program activities. In general, these reports summarize types of
environmental damages and associated mining waste management practices at sites on (or proposed
for) the NPL as of February 11, 1991 (56 Federal Register 5598). This summary report is based on
information obtained from EPA files and reports and on a review of the summary by the EPA Region
X Remedial Project Manager for the site, Robert Keevit.
It is important to note that much of the background information used to prepare this Site Summary
Report came from a Remedial Investigation conducted by the site owner, Aluminum Company of
America (ALCOA), and that report has not been reviewed and approved by EPA or the Washington
Department of Ecology.
SITE OVERVIEW
The ALCOA site, which covers several hundred acres, is located on the Columbia River about 3 three
miles northwest of downtown Vancouver, Washington (Clark County). The site consists of three
waste piles containing about 66,000 tons of waste that were deposited on the north bank of the
Columbia River by ALCOA between 1973 and 1981 (see Figure 1). The waste consists of spent
potlinings and aluminum oxide (alumina) insulation. Contaminants detected in the ground water in
the area surrounding the piles include cyanide, fluoride, and trichloroethene (TCE). The aluminum
smelter operation is now owned and operated by three companies, VANALCO, VANEXCO, and
ACPC, although ALCOA retains ownership of the property where the piles are located. Although the
piles are no longer in use, the smelter is in operation.
The piles are located along the north bank of the Columbia River near the shipping dock
(approximately 300 to 500 feet from the shoreline). Several railroad tracks go through the area where
the piles are located. The site is completely surrounded by chain-link fence topped with barbed wire.
Industrial wells, which provide all of the water used at the facility (primarily cooling water), are
located as near as 150 feet north of the three waste piles [According to the Health Assessment
(Reference 3, page 4), these wells also supply potable water for use at the plant] Municipal wells,
1

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Mining Waste NPL Site Summary Report
which provide water to 50,000 Vancouver residents, are located 3 miles east of the piles. Ground
water is also used to irrigate almost 300 acres of cropland within 3 miles of the site.
The plant is in an undeveloped area west of Vancouver. Three farms, located east of the plant, are
operated on property leased from ALCOA. Cattle are the primary stock on these farms, and hay
crops are grown as well. The farm nearest to the plant is located along the northern fence line,
approximately .5 mile northeast of the waste piles. Potable water is provided to the three farms by
domestic wells that are located within a 1-mile radius of the ALCOA plant, upgradient from the piles.
A State game preserve is located approximately 3 miles west of the plant property. Hunting is not
permitted. The Columbia River is used for commercial and recreational fishing. Species found in the
Columbia River include Steelhead, American Shad, White Sturgeon, Eulachon, and five species of
salmon.
A Health Assessment, prepared by the U.S. Public Health Services Agency for Toxic Substances and
Disease Registry was completed in May 1990 (Reference 3). As noted above, the Remedial
Investigation for the site, which was prepared by ALCOA, has not yet been approved by EPA or the
State.
OPERATING HISTORY
The ALCOA facility, primarily consisting of an aluminum reduction plant with associated support
facilities, was constructed in 1940 and began primary aluminum smelter operations late that year
The facility produced aluminum using the Hall-Heroult electrolytic cell process In this process,
molten aluminum is produced by passing a direct electrical current through alumina that has been
dissolved in a bath of molten salts (cryolite) and aluminum fluoride The process takes place in a cell
or pot lined with alumina insulation and carbon. This cell generally fails after 3 to 5 years When
the pot fails, waste materials must be removed (Reference 1, page 6; Reference 2, page 2). Fresh
potlining is generally composed of carbon, fluoride, sodium, aluminum, silicon, iron, and calcium.
Aluminum nitride, aluminum carbide, cyanide, sulfur, and phosphorous may also be present in trace
amounts (Reference 1, pages 8 and 9; Reference 3, page 1).
Prior to the 1950's, ALCOA deposited Spent Potlinings (SPLs) and alumina insulation in the same
general vicinity as the current piles. Because disposal of the wastes was not strictly controlled during
that period, waste materials may have been deposited east and west of the existing piles (Reference 1,
page 7).
3

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Aluminum Company of America
In 1948, flood waters surrounded the ALCOA facility. Berms were constructed and extensive
grading was done. The waste piles were not incorporated into the berms, rather, they remained
intact. The southeast portion of the plant site was covered by sediments deposited from the flood
(Reference 1, page 7).
Beginning in the 1950's and continuing through 1973, waste materials were taken offsite to Reynolds
in Longview, Washington, for cryolite recovery. Between 1973 and 1981, waste materials were
stored onsite in three waste piles. The first pile contains 48,000 tons of SPL generated between 1973
and 1981. The second pile contains approximately 10,000 tons of Reclaimed Alumina Insulation
(RAI) generated between 1977 and 1978. (Before 1977, RAI materials were recycled onsite.) These
two piles were covered, as described below, in 1978 (Reference 1, page 8).
The third pile contains approximately 8,000 tons of SPL and RAI waste materials generated between
1978 and 1981. This pile was covered in 1981. [From 1981 until 1983, SPL was disposed of in a
landfill at ALCOA'S Wenatchee, Washington, plant. Since 1983, it has been shipped to a Resource
Conservation and Recovery Act (RCRA) treatment and storage disposal facility located in Arlington,
Oregon.] The covers on each pile are constructed of a 12 mil Polyvinyl Chloride (PVC) liner placed
between two 12- to 18-inch layers of sand. The piles are vegetated (Reference 1, page 9, Reference
3, page 2). The covers do not extend to the toes of the piles, and surface drainage from the covers
infiltrates into the piles along these edges (Reference 1, page 9). In addition, some tears and holes
were noted in the liner both during the Remedial Investigation and subsequently (Reference 1, page
20; Reference 2, page 5; Reference 3, page 2). Figure 1 shows the location of the three piles at the
site (as well as the ground-water monitoring well locations).
SITE CHARACTERIZATION
The ALCOA plant is located on the Columbia River lowland. The ground surface is relatively flat.
The major topographic features at the site are the waste piles (which reach approximately 38 feet
above sea level) and the flood control berms (with top elevations of 34 feet above sea level)
(Reference 1, pages 10 and 11).
The climate in the Vancouver area consists of relatively mild, wet winters and moderately warm, dry
summers. The average annual temperature is 55°F and the average annual precipitation is about 40
inches (Reference 1, page 11).
Although the primary mechanism of contaminant transport and potential exposure was identified in the
Remedial Investigation as ground-water flow (Reference 1, page 19), discrete aquifers below the site
4

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Mining Waste NPL Site Summary Report
have not been clearly delineated. The hydrogeology of the site is described as three upper zones with
an additional "aquifer zone" beneath the three upper zones (see Figure 2).
The shallow zone consists of 10 feet of dredged sand. This zone is underlaid by the intermediate
zone, consisting of silt with sand and clay lenses. The deep zone, which consists of 40 feet of fine to
medium sand, underlies these two upper zones (Reference 1, page 13) According to the Remedial
Investigation/Feasibility Study report and the Health Assessment, the water table is within the
intermediate zone (Reference 1, Figure 8; Reference 3, page 4).
The predominant ground-water flow direction in the shallow zone beneath the waste pile area is to the
south toward the Columbia River Ground-water flow to the northwest is limited. The bottom 2 feet
of the shallow zone may be intermittently saturated (Reference 1, page 21; Reference 2, pages 5 and
6).
Flow in the intermediate zone is downward toward the deep zone The intermediate zone has a
relatively low permeability but a very steep vertical hydraulic gradient toward the deep zone.
Ground-water flow in the deep zone is south toward the Columbia River (Reference 1, page 22,
Reference 2, page 6).
The aquifer zone (Troutdale formation) lies at a depth of 100 to 140 feet and is composed of sand and
coarse gravel. The aquifer and deep zones appear to be hydraulically separated (Reference 2, page
6). Both the deep zone and the aquifer zone are influenced by the flow of the Columbia River, and
therefore, reverse flow may occur periodically (Reference 3, page 4).
The Remedial Investigation (July 1987) conducted by ALCOA at the site found three possible
contaminant sources, including the waste piles, waste materials mixed with soil in the vicinity of the
waste piles, and contaminants previously absorbed into soil that are not being released. The potential
exposure pathways from the waste piles are airborne particulates, surface-water runoff, migration of
gases generated within the piles, and ground-water flow. Ground-water flow was determined to be
the primary mechanism of contaminant transport and potential exposure (Reference 1, page 19) The
constituents of greatest concern were cyanide and fluoride.
Ground Water
Ground-water samples were taken in November 1986 and March 1987 (Reference 1, page 29).
Remedial Investigation data suggest that the ground water beneath the site has been contaminated by
leaching of waste pile constituents. Cyanide and fluoride concentrations in the ground water are of
5

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Monitoring Wall Number
Production vyell Number
Offset distance and Direction
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0	200	400
0	4
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Mining Waste NPL Site Summary Report
the greatest concern. Low concentrations of several priority pollutant organic chemicals and metals
were also detected, although some of the organic chemical levels detected are suspected to be due to
laboratory contamination. According to the EPA Remedial Project Manager for the site, additional
sampling has shown that there is TCE contamination in the ground water, including water from
ALCOA's production wells.
Total ground-water concentrations (based on samples taken from all ground-water zones) of cyanide
ranged from less than 0.005 to 400 mg/1, and free cyanide concentrations ranged from less than 0.005
to 1.1 mg/1. Cyanide data for the aquifer zone (collected for the Remedial Investigation) show very
little contamination, with the highest concentrations along the Columbia River (Reference 1, page 32).
Fluoride was detected at concentrations of less than 2.0 to 1,200 mg/1 in the ground water (Reference
2, pages 7-8). The Health Assessment reported concentrations of fluoride ranging from 0.015 to
11,517 mg/1 (Reference 3, page 3) The Maximum Contaminant Level (MCL) for fluoride is 1 4 to
2.4 mg/1. The fluoride data show relatively low concentrations, near background levels, in the
aquifer zone (Reference 1, page 30).
Toxicity is generally related to free cyanide (Reference 1, pages 39 and 40). The concentration of
free cyanide in the ground water at the ALCOA site has been less than 1 percent of the total cyanide
concentration. Data collected during the Remedial Investigation indicate that approximately 0.0004
pounds per day (ppd) of free cyanide is discharged to the river at the ALCOA site; the NPDES limit
is 0.15 ppd of cyanide (Reference 1, page 3). Iron cyanides, the most important iron complex at the
site (based, according to the Remedial Investigation, on experience with comparable aluminum sites),
are very stable and are not expected to contribute to the free cyanide fraction at the site. Although
iron cyanides have a demonstrated salmonid toxicity, lethal doses are much greater than any
concentration anticipated to be discharged into the waters surrounding the site (Reference 1, page 40).
A plume of contaminated ground water extends from the piles to the Columbia River. The high
concentrations of fluoride observed within the vicinity of the site preclude utilizing the area ground
water for domestic use. However, the Remedial Investigation's hydrogeologic analysis concluded that
the predominant ground-water flow is toward the Columbia River, and therefore, the river would be
the only major ecological receptor associated with the site (Reference 1, page 41). Because of their
locations upgradient of the waste piles, there is a low probability that current municipal and domestic
wells will be affected by the contamination.
The Remedial Investigation indicated that there is significant infiltration of precipitation into the piles
causing the ground water to become contaminated in the shallow zone, where it may migrate to the
Columbia River or other ground-water zones Although contamination can migrate through the
ground water to the river, the dilution factor in the river is great enough that there does not appear to
7

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Aluminum Company of America
be a significant accumulation of contaminants at this time. The average flow rate of the river at
Vancouver is approximately 200,000 cubic feet per second (cfs). Measurements of cyanide and
fluoride in the river at the ALCOA site have been less than 0.005 and 0.15, respectively; these
concentrations are equivalent to background concentrations (Reference 1, page 37).
Soils
Approximately 100 soil samples were collected in August and September 1986 to determine if
significant amounts of waste materials are present in the soils near the waste piles (Reference 1, page
31). Soil concentration data from the shallow zone shows higher levels of fluoride in the immediate
vicinity of the piles, in the area west of the piles, and northeast of the piles. The primary area of
contamination for cyanide in this zone is south of the piles In the intermediate zone, data indicate
that fluoride and cyanide become concentrated In the deep zone, soil concentration data show higher
concentrations of fluoride north and northeast of the piles. Sampling of soil cyanide revealed several
hot spots within the shallow and intermediate zones; otherwise, concentrations were "fairly low " For
both cyanide and fluoride, Remedial Investigation sampling found no indication of significant
accumulation within the deeper geohydrologic units (Reference I, page 39).
Surface Water
The Remedial Investigation conducted by ALCOA indicated that the very large flow in the Columbia
River at Vancouver would greatly dilute any contamination. Measurements of cyanide and fluoride
concentrations in the Columbia River at ALCOA have been equivalent to background concentrations
(Reference 1, page 37).
Air
The Remedial Investigation concluded that the waste piles do not appear to be a source of dust.
Although gases with an ammonia odor are being generated within the piles, the odors are only
noticeable within several inches of the piles, and the piles are located in a well-ventilated area
(Reference 1, page 38; Reference 2, page 9). As long as the piles are undisturbed, the release of
ammonia gas does not appear to be of concern (Reference 3, page 5).
ENVIRONMENTAL DAMAGES AND RISKS
The Remedial Investigation (July 1987) concluded that "impacts upon the Columbia River associated
with the discharge of groundwater containing cyanide and fluoride would appear to be non-detectable
8

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Mining Waste NPL Site Summary Report
relative to water column concentrations and minimally localized, if at all, to areas of groundwater
seepage" (Reference 1, page 44). As noted, the Remedial Investigation has not been approved by
EPA or the State.
The hydrogeologic assessment conducted during the Remedial Investigation indicates that drinking
water supplies are not presently threatened by contaminant migration. The locations and depths of the
three domestic wells located within 1 mile of the site prevent them from being contaminated by
ground water in the vicinity of the ALCOA waste piles (Reference 2, page 7). As noted, however,
TCE has been detected in ALCOA's production wells.
The primary potential human exposure pathways appear to be the ingestion of contaminated ground
water, consumption of contaminated fish, and incidental ingestion of, or direct contact with,
contaminated surface water or sediments. Ingestion of ground water is considered to be the primary
public health concern (Reference 3, page 5). Data from the Remedial Investigation (July 1987)
indicate that the contaminant levels in the ground water are not high enough to significantly affect the
water quality in the river. The Health Assessment (May 1990) states that the samples taken from the
river are not adequate to confirm this. Potential contamination of the surface water, sediment, and
fish in the Columbia River with cyanide and fluoride is a public health concern because of the
recreational and commercial activities occurring on the river Fish in the Columbia River near
ground-water recharge areas may bioaccumulate contamination. The occurrence of biota and
sediment contamination has not been determined because no samples have been collected or analyzed
(Reference 3, pages 4 through 6).
Contamination of game animals in the vicinity of the ALCOA site does not seem likely because the
waste materials of concern are generally well-contained and the piles are surrounded by a fence
(Reference 3, page 5).
The Health Assessment concluded that "since no sampling of biota or sediment and inadequate
sampling of surface water has been done, chemical-specific discussions on health implications in these
environmental media are not possible" (Reference 3, page 5).
Cyanide may cause extreme poisoning in humans although concentrations found in SPL are not great
enough to cause cyanide poisoning, according to the Health Assessment. Cyanide may potentially
cause low blood pressure, tachycardia (rapid heart beat), headache, drowsiness, coma, convulsions,
cytotoxic anoxia, and other central nervous system disorders (Reference 3, page 6).
The potential effects of fluorides include thermal or chemical skin burns and irritation of the eyes,
mucous membranes, and lungs. Ingestion may cause nausea, vomiting, abdominal cramping, and
9

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Aluminum Company of America
diarrhea. Ingestion of large doses may cause Central Nervous System depression or renal failure, and
excessive doses may lead to osteosclerosis (Reference 3, page 6)
TCE has been designated at a potential human carcinogen. Long-term exposure could result in
increased risk of cancer as well as liver damage and depression of immune function (Reference 3,
page 6).
REMEDIAL ACTIONS AND COSTS
A Feasibility Study was completed in July 1987. At this time, there is no record of any decision
regarding remedial action to be taken at the ALCOA site.
The Feasibility Study estimates that continued ground-water monitoring and testing at the site using
existing wells (20 wells sampled four times a year for 30 years) will cost $310,000. Onsite
containment is expected to cost between $1,360,000 and $3,610,000 depending upon the containment
method used: earth cover with site grading; earth cover with site grading and paving; or earth cover
with site grading and pumping and treating ground water are the options considered. Waste removal
from the site will cost an estimated $12,500,000 to $14,700,000 Source removal alternatives include
disposing of the waste material in a landfill and grading the site, disposing of the waste material in a
landfill and grading and paving the site; and disposing of the waste material in a landfill, grading the
site, and pumping and treating ground water (Reference 2, page 35 through 40).
Based on the Feasibility Study evaluation, the preferred alternative consists of "leaving the wastes in
place, constructing an earth cover and grading the site so that surface water drains away from the pile
area" (Reference 2, page 41). Ground-water monitoring would also be conducted (Reference 2, pages
41 and 42).
One other alternative being evaluated is to move the waste material into a RCRA building and recycle
the material at a later date. The site would be graded (Reference 5). Again, it should be noted that
the Remedial Investigation/Feasibility Study prepared by ALCOA has not been approved by EPA or
the State (Reference 4).
CURRENT STATUS
The Remedial Investigation/Feasibility Study completed by ALCOA in July 1987 is still subject to
final review by EPA. A Record of Decision has not been completed
10

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Mining Waste NPL Site Summary Report
REFERENCES
1 Remedial Investigation, Aluminum Company of America, Vancouver Operations, Volume I;
Prepared for ALCOA by Hart Crowser; July 27, 1987.
2.	Feasibility Study, Potlining Waste Piles, Aluminum Company of America, Vancouver Operations;
Prepared for ALCOA by Hart Crowser; July 27, 1987.
3.	Health Assessment for ALCOA (Vancouver Smelter), Vancouver, Clark County, Washington;
Agency for Toxic Substances and Disease Registry, U.S. Public Health Service; May 9, 1990.
4.	Telephone Communication Concerning Aluminum Company of America From Mary Wolfe,
SAIC, to Robert Keevit, EPA Region X; August 14, 1990.
5 Feasibilty Study, Potliner Waste Piles, Aluminum Company of America, Vancouver Smelter
Operations, Washington; Author Unknown; Undated.
11

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Aluminum Company of America
BIBLIOGRAPHY
Author Unknown. Fe'asibilty Study, Potliner Waste Piles, Aluminum Company of America,
Vancouver Smelter Operations, Washington. Undated.
Prepared for ALCOA by Hart Crowser. Feasibility Study, Potlining Waste Piles, Aluminum
Company of America, Vancouver Operations. July 27, 1987.
Prepared for ALCOA by Hart Crowser. Remedial Investigation, Aluminum Company of America,
Vancouver Operations, Volume I. July 27, 1987.
U S. Public Health Service, Agency for Toxic Substances and Disease Registry. Health Assessment
for ALCOA (Vancouver Smelter) Vancouver, Clark County, Washington. May 9, 1990.
Wolfe, Mary (SAIC). Telephone Communication Concerning Aluminum Company of America to
Robert Keevit, EPA Region X. August 14, 1990.
12

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Aluminum Company of America
Mining Waste NPL Site Summary Report
Reference 1
Excerpts from Remedial Investigation, Aluminum Company of America,
Vancouver Operations, Volume I; Prepared for ALCOA by Hart Crowser;
July 27, 1987

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J-l759-02
REMEDIAL INVESTIGATION
ALUMINUM COMPANY OF AMERICA
VANCOUVER OPERATIONS
VANCOUVER, WASHINGTON
INTRODUCTION
This report presents che results of the Remedial Investigation (RI) for the
Alcoa Vancouver Operations facility. The RI assesses the environmental
effects of contaminants leaching from spent potllnlng (SPL) and reclaimed
alumina insulation (RAI) materials produced during the reduction of alumina
Into aluminum metal. This work represents the second phase of the Remedial
Investigation/Feasibility Study (RI/FS) process. During the first phase, a
preliminary assessment was completed to compile and analyze previously
available data related to groundwater quality In the vicinity of the waste
piles at the Alcoa facility. The results of the preliminary assessment
were Included in our report dated August L, 1986 entitled "Preliminary
Assessment of Groundwater Quality Conditions, Aluminum Company of America,
Vancouver Operations, Vancouver, Washington."
The general objectives of the RI are to: 1) assess the nature and extent
of contamination, 2) collect information needed to identify likely
receptors of contamination and evaluate public health and environmental
risk, and 3) collect information needed to evaluate remedial actions to
mitigate any hazards assbciated with exposure to contamination. The
specific tasks Included la the remedial investigation are described in the
technical scope of work included with the preliminary assessment report.
The project was authorized under Alcoa purchase order number W112334VW,
dated December 5, 1986 and May 13, 1987.
The Feasibility Study portion of che RI/FS, which is included in a
separate report, presents the evaluations of various remedial action

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J-1759-02
Page 3
o The primary receptor of groundwater contaminated with cyanide and
fluoride is the 'Columbia River. The environmental impacts of the
contaminated groundwater reaching the Columbia are negligible.
o The nearest municipal water-supply wells are located approximately three
miles to the northeast and upgradient of the waste piles. The potential
for contaminant migration from the site to the wells is remote.
o Three domestic wells are present within one mile of the plant. Only one
of these wells is in use. These wells are located either upgradient or
crossgradient from the waste piles. The potential for contaminant
migration from the pile area to these wells is low.
o Industrial wells which provide predominantly cooling water to the
facility tap the aquifer zone. The nearest wells are located
approximately 150 feet to the north and upgradient of the waste piles.
Our analyses indicate that the wells remain upgradient of the waste
piles during pumping.
o Free cyanide generally comprises less than one percent of the total
cyanide in groundwater at the Alcoa site. The amount of free cyanide
that is discharged into the river is estimated to be roughly 0.0004
pounds per day. This estimate is well below the NFDES limit of 0.15
pounds per day of cyanide.
o The highest concentration of free cyanide that has been observed in the
groundwater monitoring wells during the sampling period from September
1986 through March 1987 was 1.1 ppm. EPA'3 revised ambient water
criteria for cyanide is 3.77 mg/L (ppm) (49FR4551, February 1984).
o The highest concentration of fluoride that has been observed in the
groundwater monitoring wells during the sampLlng period from September
1986 through March 1987 was 136 ppm. EPA's drinking water standard for
fluoride is 4.0 mg/L (ppm). Approximately lj pounds per day is

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J-1759-02
Page 6
o A detailed topographic map vas developed to evaluate site drainage and
to facilitate the development and evaluation of possible remedial
actions.
o Hydraulic conductivity measurements were made in all the monitoring
veils. These data were used to calculate groundwater flow rates and
contaminant loadings to the Columbia River.
o An assessment of the integrity of the cover systems vas performed. At
selected locations the synthetic membrane vas exposed and its general
physical condition assessed.
o Exploratory borings were completed through the vaste piles to	determine
the elevation of the bottom of the piles. Test pits were	completed
along the southern edge of the vaste piles to determine	if waste
materials were present.
SITE HISTORY
An historical profile of the Alcoa Vancouver operations vas developed during
the preliminary assessment. This profile vas developed by reviewing aerial
photographs and by interviewing past and present employees of Alcoa.
Waste Disposal Practices
The Alcoa Vancouver facility vas initially constructed In 1939 and 1940 and
started operations in late 1940. The facility produced aluminum using the
Hall-Heroulc electrolytic cell process. In this process, molten aluminum
is produced by passing a direct electrical current through a solution of
aluminum oxide (alumina) that has been dissolved in a bath of molten salts
(cryolite) and aluminum fluoride. The entire process occurs in a rectan-
gular steel pot that is lined vith alumina insulation and carbon potlinlng.
A pot is used until the integrity of the carbon potlinlng is breached, at
vhich time the potlinlng and alumina insulation materials must be removed

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and replaced. This typically occurs every three to five years. At the
Alcoa Vancouver facility. Che potlinlng materials were removed by soaking
the pots with vater. This soaking would soften the potlining. After
soaking, Che waste was removed from the pot and transported to the waste
handling area. The pot was not removed from the aluminum reduction
building during this process. The vater used for soaking would all
evaporate from the pots.
The spent potlinlng (SFL) and reclaimed alumina insulation (RA1) materials
were temporarily stored on-site during the early years of operation. Our
review of aerial photographs and our interviews Indicate that the wastes
were handled primarily in the general area now occupied by the existing
waste piles. A photograph of the plant taken in 1948 clearly shows waste
piles in the area of the existing piles. During these early years
deposition of the waste was not as strictly controlled as in later times
and some isolated loads may have been deposited west and east of tha
existing piles.
In 1948, flood waters of the Columbia River surrounded the Alcoa plant.
Berms were constructed and extensive grading occurred. Although some small
amounts of potlinlng may have bees moved during Che grading, the 1948
photograph of the plant site indicates that the waste piles remained Intact
and were not Incorporated Into the berms. Sediments deposited by the flood
covered most of the southeast portion of the plant site.
The waste materials were shipped off-site to Reynolds in Longvlew,
Washington for cryolite recovery starting in the early 1950s. The materials
were loaded onto railway cars using the tracks that are adjacent to the
existing piles. This shipping continued until 1973.
Between 1973 and 1981, waste materials were stored on site. There are
three waste piles on the site. The largest pile contains spent potlinlng
materials that were produced between 1973 and 1978. The next largest pile
contains RAI materials that were generated between 1977 and 1978. These

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materials had been temporarily stored on a paved area northwest of the
potrooms. Prior to 1977, the RAI materials were recycled on-site.
The two piles were covered In 1978. RAI and SPL materials that were
generated at the Alcoa facility between 1978 and 1981 are combined in a
third pile that was covered in 1981. From 1981 until 1983, SPL was
disposed of In a landfill at Alcoa's Wenatchee, Washington plant. From
1983 until June 1986 the wastes were shipped to the hazardous waste
landfill located in Arlington, Oregon.
Previous Site Assessments
Nine shallow groundwater monitoring wells were Installed In the area of the
waste piles In 1977 (Robinson, Noble, and Carr, Inc., 1981). Cyanide was
detected In these monitoring wells. Additional monitoring wells were
inscalled in 1980, 1981, and 1984 (Robinson, Noble, and Carr, Inc., 1981;
Robinson and Noble, 1982; Robinson and Noble, 1984). A total of 38
monitoring wells were installed prior to the presene study. Water levels
and groundwater samples were collected from each monitoring well on a
monthly basis after 1982. The groundwater samples were analyzed for total
cyanide. Selected samples were analyzed for free cyanide. The results of
these analyses are Included in the preliminary assessment report (Hart
Crowser, 1986).
Waste Pile Characterization
Approximately 66,000 tons of waste materials are reported by Alcoa co
remain on-site. AbouC 10,000 of these tons are stored in the RAI pile;
48,000 tons are in the first potlinlng pile; and 8,000 tons are in the
second potlinlng pile.
While no detailed waste pile sampling was conducted, the approximate
composition of these piles can be estimated based upon the knowledge of the
composition of typical fresh potlinlng. Fresh potlinlng is generally
composed of carbon, fluoride, sodium, aluminum, silicon, iron, and

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Page 9
calcium. These seven consticuencs are generally present in amounts greater
than I percent. Trace amounts of aluminum nitride, aluminum carbide,
cyanide, sulfur, and phosphorous may also be present.
The constituent that causes the most environmental concern is cyanide. The
average amount of cyanide in fresh potlinlng is in the range of 0.03
percent to 0.5 percent. The actual cyanide concentration can be only a few
parts per million or as much as several percent, depending upon the
location in the pot.
Leaching tests using the EP toxicity procedure indicate that samples of
fresh potlinlng vould not be classified as a dangerous waste based on
metals concentrations. The leachate that vas generated from the procedure
was very alkaline and contained cyanide.
Fish bioassay testing of the same samples determined that the fresh
potlinlng produced at Alcoa's Vancouver facility is classified as an
extremely hazardous waste under Washington State regulations. Potlinlng is
currently exempt from RCRA listing as a hazardous waste.
In 1978 the wastes stored on the Alcoa site were graded, formed into two
piles and covered to prevent precipitation from contacting the waste and
causing contaminants to migrate to the water table. The cover system
consists of a 12 mil PVC synthetic membrane placed between two 12- to 18-
inch-thick layers of sand. Vegetation vas placed over the final cover. A
similar cover system was Installed on a third waste pile In 1981.
The covers do not extend past the toes of the pile. Surface drainage from
the covers infiltrate into the piles along these edges.
GENERAL SETTING
Figures 1 through 3 present regional, vicinity, and site maps showing the
location of the Alcoa Vancouver facility. The regional map, Figure 1, shows
an area within an approximate ten mile radius of the site. The vicinity

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Page 10
map, Figure 2, shows the area within a four mile radius of che aluminum
reduction plaac and the sice map. Figure 3, shows che area within
approximately 1500 feec of the waste piles. The Alcoa facility is located
approximately three miles northwest of downtown Vancouver in an area that
is primarily industrial or is undeveloped.
The City of Vancouver operates several municipal water wells three to four
miles east of the Alcoa facility. The locations of these wells are shown
on Figure 2. The nearest well is located on a terrace approximately three
miles from the waste piles. The surface elevation of the well is
approximately 220 feet above mean sea level (HSL) and the veil is screened
froo elevation 0 to elevation -30 feet. The elevation of the plant site
ranges from about 25 to 35 feet HSL.
The waste piles are located 300 to 500 feet north of the shoreline of che
Columbia River, as shown on Figure 3. Hater supply wells located
immediately north of the waste piles (Figure 3) provide all water used at
the plant. Additional Alcoa water supply veils are located about 1500 feet
northwest of the waste piles. These veils, which were used to supply water
for air scrubbers, are no longer used.
Three domestic veils are located within a one-mile radius of the Alcoa
plant. These veils, all less than 100 feet deep* are north of the site and
east of the site. The veils are located upgradlenc from the piles. Their
depth and location prevent them from being impacted by contaminant
migration from the Alcoa site.
Topography, Climate, and Surface Water Features
The topography, climate, and surface vater features of the Alcoa Vancouver
facility are described In the preliminary assessment report (Hart Crovser.
1986). This Information is summarized below.
The Alcoa Vancouver facility is located on the Columbia River lovland. The
ground surface in the vicinity of che plant is relatively flat wich

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elevations Increasing from approximately 20 feet in the south along the
river to 35 or AO feet in the northern and eastern portions of the site.
The major topographic features at the site are the waste piles, which have
a top elevation of approximately 38 feet, and flood control berms, which
have top elevations of approximately 34 feet.
The general climate In the Vancouver area consists of relatively mild, wet
winters and moderately warm, dry summers. Figure 4 shows average monthly
temperatures for Vancouver. The average annual temperature at the
Vancouver weather station is approximately 55 degrees Fahrenheit. The
average annual precipitation is approximately 40 Inches. There are no
evaporation measurement stations in the Vancouver area. Data from a
measurement station in Astoria, Oregon, about 60 mllea vest of Vancouver,
Indicate an average annual surface-water evaporation rate of 22 inches.
Precipitation usually exceeds evaporation In all months except June, July,
and August as shown on Figure 5. On an annual basis, groundwater recharge
from precipitation is estimated to average approximately 20 inches per
year. This corresponds to roughly 1 ogd per square mile.
The principle surface water feature in the vicinity of the Alcoa Vancouver
facility Is the Columbia River. The river Is the main trunk stream for the
entire Northwest. All surface streams In Clark County discharge into the
river. It Is base level for groundwater so that any groundwater leaving
the county does so by discharging into the river or one of Its tributaries.
Discharge data for the Columbia has been compiled by the U.S. Geological
Survey at river mile 106.5 approximately 3.5 miles upstream from the Alcoa
facility. There are no major tributaries feeding the river between this
station and the Alcoa site. The average annual discharge for the Columbia
River at the Alcoa site is estimated to be 200,000 cubic feet per second
(cfs). Peak flows average approximately 400,000 cfs and generally occur in
June, as shown on Figure 6. Low flovs average approximately 100,000 cfs
and occur in October and November. The probable maximum flood at Vancouver
is estimated to be 1.5 million cfs, which is equivalent to a river stage

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Page 13
Site Hydrogeology
The groundwater system at Alcoa can be divided into four general zones:
the shallow zone, the Intermediate zone, the deep zone, and the aquifer
zone. The relative positions of these zones are shown on Figure 8. The
trend of the section is shown on Figure 3. The shallow zone consists of
approximately 10 feet of dredged sand. The Intermediate zone consists of
30 to AO feet of silt vlth lenses of clay and fine sand. The top of the
intermediate zone was the original ground surface before the dredged sands
were placed over the site. The deep zone consists of fine to medium sand
approximately 40 feet thick. The aquifer Is comprised of coarse sand and
gravel between 100 and 140 feet below the ground surface.
The aquifer and deep zones are differentiated by a change in material
type. The aquifer materials are much coarser than the sand comprising the
deep zone. Stratifications and laminations within the deep zone cause the
vertical permeability to be considerably lower than the horizontal
permeability. This in turn causes the two units to behave as separate
hydraulic units.
The horizontal hydraulic conductivity of the dredged sands is in the range
-3	-4
of 10 to 10 cm/sec. The horizontal hydraulic conductivity of the silt
-4	-6
materials generally ranges from 10 to 10 cm/sec. The hydraulic
-2	-4
conductivity of the sand comprising the deep zone ranges from 10 to 10
cm/sec, although there are silt lenses that have conductivities on the
-6
order of 10 cm/sec. The aquifer materials have hydraulic conductivities
-2	-3
ranging from 10 to 10 cm/sec.
The ln-situ tests used to measure hydraulic conductivity generally measure
horizontal values. Vertical hydraulic conductivities are often considerably
less than horizontal values, especially in layered deposits. Laboratory
permeability testa conducted on samples taken from the silt materials com-
prising the intermediate zone indicate that vertical hydraulic conductivi-
ties may be an order-of-oagnltude less than horizontal values. The results
-7	—8
of the laboratory tests show values in the range of 10 to 10 cm/sec.

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The general mechanisms for transporting and exposing fluoride and cyanide
contamination from the waste piles are 1) air-borne particulates, 2) surface
water run-off, 3) migration of gases generated within the piles, and 4)
groundwater flow. The primary mechanism of contaminant transport and
potential exposure is via groundwater flow.
The evaluation of the effects of groundwater contamination involves three
general tasks. These are 1) identifying contaminant sources. 2) determining
groundwater flow directions and flow rates, and 3) estimating contaminant
concentrations as a function of time and space. Our assessment of each of
these three components is presented below.
Contaminant Sources
Possible contaminant sources at the sice Include 1) the waste piles. 2)
waste materials mixed with soil in the vicinity of the waste piles, and 3)
contaminants previously absorbed onto soil that are now being released. No
other sources were identified during the field activities.
Approximately 66,000 tons of waste materials remain on-site (Figure 3).
About 48,000 of these tons are in the larger potllning pile (pile No. 1);
10,000 tons are stored in the RAI pile (pile No. 2), and 8,000 tons are in
the smaller potllning pile (pile No. 3). The constituent that causes the
most environmental concern is cyanide.
The constituent that causes the most environmental concern is cyanide. The
average amount of cyanide in fresh potllning is in the range of 0.03
percent to 0.5 percent. The actual cyanide concentration can be only a few
parts per million or as much as several percent, depending upon the
location in the pot.
Our assessment of the integrity of the waste pile cover suggests that
significant amounts of precipitation may infiltrate into the potllning and
RAI materials under current pile conditions. Figure 16 illustrates areas
along the SPL waste pile that are Inferred to contain uncovered wastes.
These inferences are based upon the indicated observation points.

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Page 20
Run-off from che covers collects along the base of Che pile and likely
infiltraces into the waste piles. Ac several locations along che sides and
cop of che pile, che liner was Corn and liner seams were separated.
Ammonia-like odors were decected ac ehese locations. At other locations,
che cover material was in very good condition. The amount of infiltration
along tears and seams is likely of secondary importance when compared co
the amoune of lnfileraclon along che uncovered edges.
Test pits along che souchern edges of che waste piles (Figure 16) also
Indicated that uncovered waste materials are present south of pile No. 1
between the pile and the railroad tracks. No waste materials were observed
south of pile No. 2.
The exploratory borings completed through the waste piles showed (Figure
16) that the potliniag materials vere placed on top of Che dredged sand.
The materials are not in contact vlth groundwater. Vatar which flows
through Che dredged sand along the top of th« silt layer would not contact
the potliniag material.
The second source of contamination is a small amount of waste material
mixed with soil. Data collected during our preliminary assessment Indicated
that small amounts of potllnlng and &AI materials may be present in the
soils east and west of the wast* piles. The large flood of 1948 and
subsequent grading activities may have spread some of the waste materials.
It is our understanding that a limited amount of uncontrolled dumping
during the very oarly years may also have occurred in this general area.
The results of analyses of soil samples collected during monitoring well
installation show that some waste materials may be present near the ground
surface northeast of the piles In the vicinity of monitoring wells KV-22,
MW-23, MV-35, and KW-33. Additional samples collected In these areas showed
that the waste materials are located in very small areas. Samples were
collected in grids and then composited. The location of the grids are shown
on Figure 13 and the results of the laboratory analyses are Included in
Table A-2.

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Page 21
The third source of contamination are soils chac may have absorbed
contaminants from groundwater before the piles were covered. The pH of the
groundwater in the vicinity of the waste piles ranges from near neutral to
very basic. The background pH is approximately 6 at the Vancouver site.
This more acidic water may cause the gradual release of available free
cyanide. The metallic cyanide complexes would not be released at a
groundwater pH of 6.
It is likely that each of the three contaminant sources discussed above
contribute to the groundwater quality conditions at Alcoa to some degree.
However, the largest source, by several orders-of-tnagnltude, is the result
of infiltration into the waste piles.
Groundwater Flow Directions
The second task in evaluating the effects of groundwater contamination is
to determine groundwater flow directions and flow rates. Flow directions
and rates can be inferred from three general sets of information: 1) water
level measurements, 2) water quality analyses, and 3) soil quality
analyses. The water level measurements provide a "snapshot" of flow
directions while the water qualley data provide a more average
representation of flow directions. The soil quality data can be used to
infer flow directions thac may have occurred in the past. Ideally, all
three sets of information should provide a consistent picture of the
groundwater flow directions.
During the wetter months of the year, groundwater becomes perched in the
dredged sands (shallow zone). This perched groundwater initially drains to
low spots in the original site topography. The locations of these low
spots, as shown on Figure 17, are to the west of the piles. After the low
spots become filled with water, the groundwater generally flows to the
south toward the Columbia River, as shown by the water level contours
presented on Figures 18 and 19. The November 1986 and March 1987 water
quality data for the shallow zone, shown on Figures 20 through 23, show
relatively higher cyanide and fluoride concentrations In the areas west of

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Page 22
che piles, as expected. Although che soil concentrations for cyanide,
presented on Figure 24, show flov to the south, che soil concentrations for
fluoride, presenced on Figure 25, shov higher values to che vest. The
reasons the fluoride in the soil is more widely distributed than cyanide
may be related to the fact that the fluoride is more stable and is less
likely to be attenuated.
A comparison of water level contours prepared using data collected in
October 1986 (Figure 18) and in May 1987 (Figure 19) show that water levels
in the shallow zone Increase during the wet season by as much as U feet.
The general groundwater flow direction during the wet season, as shown on
Figure 19, Is still toward the low spot west of the plies and to the south
toward the Columbia River.
Monitoring wells MW-36 through Ktf-40 were installed In May 1987 to
determine the areal extent of contamination in the shallow zone west of the
waste piles. The results of analyses of flourlde and cyanide In the
groundwater in these wells are presented in Table A-17. These results
suggest that the low spot in the original topography pinches out in the
direction of MW-38 and that cyanide and fluoride are not migrating
significant distances beyond well MW-38.
The cyanide and fluoride concentrations in the soil and groundwater In the
intermediate zone are presented on Figures 26 through 31. Flow through the
silt zone Is predominantly vertical. The presence of contamination in the
Intermediate zone south of the waste piles was likely transported down from
the dredged sands rather than horizontally through the silts.
The groundwater flow directions in the deep sand zone are generally to the
south, as indicated and by the water level data (Figures 32 and 33) and by
the total cyanide and fluoride data (Figures 34 through 39). Flow toward
the river is consistent with water quality data and with the overall
regional groundwater flow direction. Continuous water level measurements,
which are discussed below, indicate that water levels must be measured

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Page 23
within several hours co provide a reliable picture of Che groundwater flow
directions in the deep zone.
A comparison of water level contours for October 1986 (Figure 32) and Hay
1987 (Figure 33) show that water levels Increase by approximately 2 feet
during the wet season. The May 1987 data show a groundwater divide is north
of the waste piles. The groundwater flow direction in Che vicinity of
waste piles is still to the south.
Aquifer Zone
The groundwater flow directions in the aquifer zone are generally similar
to the directions is the deep zone. Flow in the aquifer zone generally
appears to be to the southwest. The groundwater fluoride and cyanide data,
shown on Figures 40 through 43, also suggest the flow direction is to the
south and west. However, Alcoa's production wells have a greater influence
in the aquifer zone than in the overlying zones.
The production wells located north of the waste piles are 100 to 140 feet
deep and are completed in a sand and gravel deposit. Data from pumping
tests performed on these wells in 1954 have been analyzed by the U.S.
Geological Survey (U.S.G.S., 1964). The analysis Indicates that the aquifer
has fairly uniform material properties over Che site. The transmlsslvlty
of the aquifer based upon these tests ranges from two to four million
gallons per day (mgd) per foot. This is an exceptionally high value. The
storage coefficient ranges from 0.0002 to 0.0006.
The production wells are generally operated three at a time. Each set of
three wells is pumped for several months. The total withdrawal from the
three wells is approximately 4 mgd to 5 mgd.
The high transmlsslvlty of the aquifer results in very flat cones of
depression around the pumping wells. Drawdowns calculated using a Thels
analysis (Freeze and Cherry, 1979) and assuming a transmlsslvlty of 3 mgd

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Page 24
per fooc and a storage coefficient of 0.0004 suggest that drawdowns In the
aquifer beneath the waste plies are predicted to be approximately 1.5 feet.
The flat cones of depression predicted with the Thels analysis Indicate that
the pumping wells do not significantly affect the flow directions of the
groundwater In the deposits overlying the aquifer. These flow directions
are likely much more sensitive to changes in the Columbia River. The
continuous water level measurements described below support this conclusion.
Continuous Water Level Measurements
The continuous water level measurements shown on Figure 15 were used to
assess the impacts that river fluctuations and production well pumping have
on groundwater flow directions. Figure 15 presents water levels in the
Columbia River from October 30 through November 18» 1986. Diurnal tidal
fluctuations caused evo to three feet of change in water levels. The
average water level remained relatively constant over the three week period.
Vater levels in monitoring wells at MW-8, which Is located approximately 600
feet north of the river and 100 feet north of the waste piles, are shown on
Figure 15. The cause of the dally rise and fall in water levels in the
intermediate zone has not yet been determined. It is not likely that these
variations are In response Co tidal fluctuations because of their magnitude
and because they occur only once a day. The rise in water levels evident
at day seven (November 6, 1986) Is likely due to precipitation events.
The water levels In the deep zone show that 1) tidal fluctuations propagated
quickly through the sand unit, 2) strong vertical gradients were present
between the intermediate and deep rones, and 3) water levels In the deep
zone did not respond to precipitation events. These observations were based
on data collected over a three-week time period. Additional monitoring
would be required to assess longer-term responses due to precipitation.
The water levels in the aquifer zone show the effects of diurnal tidal
fluctuations. The higher frequency fluctuations are due to production veil

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PW-15, which is approximately 60 feeC away. An .automatic switch activates
and deactivates the pump at PW-15 several times per day. The water levels
presented on Figure 15 indicate that 1) drawdowns in the aquifer caused by
pumping are likely small, and 2) the deep and aquifer zones behave as
separate hydrogeologic units since the high-frequency fluctuations do not
appear in the deep zone.
The water levels in monitoring wells at MW-18 near the Columbia River
behave similarly to the wells at MW-8. A comparison of the levels at MW-8
and MW-18 generally supports the assumption that the groundwater flow
direction is to the south.
Groundwater Discharge Rates
Groundwater discharge can be calculated from hydraulic conductivity
measurements and water level measurements. Uncertainties and variabilities
associated with each of these two parameters result in order-of-magnltude
estimates. The flow area widths, lengths, and thicknesses were estimated
based on rater quality conditions as well as the geologic and hydrologlc
data.
The horizontal groundwater discharge in the shallow zone between the waste
piles and the river calculated from the water levels shown on Figures 18
and 19 is approximately 60 cubic feet per day (cfd). This estimate is
based upon the following assumed values: 1) hydraulic conductivity equal to
1x10 ^ feet per minute, 2) hydraulic gradient equal to 0.02, 3) saturated
thickness equal to 3 feet, and 4) flow area width equal to 750 feet. This
estimate is likely somewhat high since it is based upon water levels
measured during October and May. The flow rates would be significantly
less during the dryer months.
The vertical flow rate In the intermediate zone beneath the waste pile is
estimated to be approximately 20 cfd. This estimate is based upon 1) ver-
tical hydraulic conductivity equal to 1 x 10 ^ feet per minute, 2) vertical

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hydraulic gradient equal co 0.6, 3) flow	area width equal to 250 feet, and
4) flov area length equal to 750 feet.
Finally, the horizontal flov rate in the	deep zone between the waste piles
and the river is approximately 700 cfd.	This estimate is based upon 1)
-3
horizontal hydraulic conductivity equal to 5 x 10 feet per minute, 2)
hydraulic gradient equal to 0.002, 3) thickness equal to 60 feet, and 4)
flov area width equal to 750 feet. For the deep zone, the area that
displays elevated cyanide and fluoride concentrations is considerably
smaller than the length of the waste pile area, which is approximately 750
feet. For estimating contaminant loadings, the plume width is assumed to
be approximately 250 feet and the plume thickness is approximately &0
feet. This results In approximately 155 cfd of groundwater flov.
Priority Pollutant Analyses
Eleven priority pollutant analyses were conducted of samples obtained from
selected wells. Ten samples were obtained on January 29 and 30, 1987. Well
MW-38B was sampled on May 19, 1987. The analytical results are presented
in Appendix 0. The results, which are included in Appendix D, indicate no
significant contamination. The specific wells and zones sampled are:
Well Number
Zone
MV-3
Intermediate
MW-11
Deep
MW-11B
Intermediate
MW-16
Intermediate
MW-16A
Shallow
MW-21B
Aquifer
MW-23A
Aquifer
MW-30A
Shallow
MW-30B
Intermediate
MW-30C
Deep
MW-38B
Intermediate
Total organic carbon (TOC) concentrations ranged from 13 to 250 mg/L while
total organic halogens (TOE!) ranged between L/0.02 to 2.8 mg/L. Wells MW-11,
MW-1IB, and MW-16 displayed the highest TOC concentrations (190 to 250 mg/L)

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while wells MW-30B, MW-30A, and MW-23A displayed Che highest TOH
concentrations (2.1 to 2.8 mg/L).
Only several organic chemicals were detected, and these at low
concentrations. The specific organic chemicals detected above trace
amounts are listed below.
Shallow Zone
Number of	Number of

Low
High
Wells Detected Veils
TOC (mg/L)
30
46
2 2
TOX (mg/L)
L/0.02
2.6
1 2
Acetone (ug/L)
L/l
17
1 2
Bis (2-ethylhexyl)
L/l
2
1 2
Phthalate (ug/L)



Endrin acetone (ug/L)
L/0.04
0.04
1 2
Intermediate Zone
TOC (mg/L)
31
250
4
4
TOX (mg/L)
0.04
2.1
4
4
Methylene Chloride




(ug/L)
Trace
140
4
4
Acetone (ug/L)
6
28
4
4
Naphthalene (ug/L)
L/l
3
1
4
2-methylphenol (ug/L)
L/l
19
1
4
Deep Zone




TOC (mg/L)
55
190
2
2
TOX (mg/L)
0.05
0.25
2
2
Methylene Chloride




(ug/L)
53
73
2
2
Acetone (ug/L)
8
9
2
2
Bis (2 methylhexyl)
6
13
2
2
Phthalate




Aquifer Zone




TOX (mg/L)
13
24
2
2
TOC (mg/L)
0.02
2.8
2
2
Trlchloroethylene




(ug/L)
L/l
20
1
2
Endrin Ketone (ug/L)
L/0.04
0.13
1
2

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Methylene chloride, acetone, and bis(2-ethylhexyl) phehalace were most
commonly detected. These chemicals are common to the laboratory
environment and are likely the result of laboratory contamination.
Dissolved priority pollutant metal concentrations vere also analyzed.
Antimony, beyIlium, lead, mercury, selenium, silver and thallium vere not
detected. The concentration range for each metal (where detected) is
summarized by zone below.



Number of
Number of

Low
High
Veils
Veils

(conc.
in ug/L)
Detected
Sampled
Shallow Zone




Arsenic
L/20
40
1
2
Cadmium
L/l
1
I
2
Chromium
L/l
4
1
2
Copper
25
43
2
2
Nickel
L/2
23
1
2
Zinc
13
32
2
n
Total Phenol
L/5
—
0
2
Intermediate Zone




Arsenic
L/20
350
3
4
Cadmium
L/l
L/10
0
4
Chromium
L/l
48
3
4
Copper
10
210
4
4
Nickel
L/2
52
2
4
Zinc
26
65
4
4
Total Phenol
L/5
100
3
4
Deep Zone




Arsenic
L/20
L/20
0
2
Cadmium
L/l
L/l
0
2
Chromium
L/l
L/l
0
2
Copper
2
3
2
2
Nickel
L/2
L/2
0
2
Zinc
15
36
2
2
Total Phenol
L/5
L/5
0
2
Aquifer Zone




Arsenic
L/20
L/20
0
2
Cadmium
L/l
L/l
0
2
Chromium
L/l
L/l
0
2

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Low
Low	High
(conc. In ug/L)
Number of
Veils
Detected
Number of
Veils
Sampled
Copper
Nickel
Zinc
Total Phenol
3
L/2
17
L/5
3
L/2
54
L/5
2
0
2
0
2
2
2
2
pH and Electrical Conductivity Data
Measurements of pH and electrical conductivity were made for groundwater
samples collected in September 1986. These measurements are tabulated in
Table A-6. The pH ranged from approximately 6 to 7 for samples collected
avay from the piles and from approximately 7 to 10 for samples in the
immediate vicinity of the piles. The electrical conductivity of the
samples are generally correlated with pH; higher conductivities vere
observed closer to the piles. The conductivities ranged from approximately
200 to 300 micromhos for samples collected away from the piles to as high
as 11,000 micromhos for samples closer to the piles.
The pH and electrical conductivity data are in general agreement vith
fluoride and cyanide concentration data. Higher values are observed near
the piles and toward the river.
Fluoride Concentrations and Fluoride Loadings
The spatial distributions of fluoride in the soil and groundwater in the
vicinity of the waste piles are Included on Figures 20 through 45. The
soil concentrations are based upon samples collected from soil borings
completed during monitoring well Installation activities in August and
September 1986. The water concentrations are based upon analyses performed
on samples collected In November 1986 and March 1987.

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The soil concentration data for Che shallow zone. Figure 25, shows higher
levels of fluoride In the immediate vicinity of the piles, in the area west
of the piles, and in the area northeast of the piles. The higher levels
west of the piles are likely due to groundwater which flows from beneath the
piles to low spots In the original site topography. The higher levels
northeast of the piles are likely due to small amounts of waste materials
mixed with the dredged sands. Additional near-surface soil samples
collected In this area indicate that the waste materials are located in
very small areas.
The water concentration data for the shallow zone, shown on Figures 21 and
23, generally concur with the soil data. No water samples were available
northeast of the piles.
The fluoride soil and groundwater concentration data for the intermediate
zone, shown on Figures 27, 29, and 31, indicate downward migration of
fluoride from the dredged sands into the silts and clays. The data suggest
that fluoride becomes concentrated within the silt zone, perhaps due to
absorption on the fine-grained materials.
The fluoride concentration data for groundwater in the deep zone, shown on
Figures 35 and 37, indicate flow toward the Columbia River. The soil data,
shown on Figure 39, show higher concentrations north and northeast of the
piles. These concentrations are likely due to vertical flow from overlying
layers rather than due to horizontal flow from the waste piles.
The fluoride data for the aquifer zone, shown on Figures 41 and 43, show
relatively low concentrations that are near background levels. As a
reference value, the concentration of fluoride in the Columbia River at the
Alcoa site is approximately 0.2 mg/L. A comparison of the groundwater
concentration data for samples collected in November 1986 and March 1987
show that relatively small changes occur. The spatial distribution in the
shallow and Intermediate zones Increase In response to increased
precipitation and infiltration. The concentrations decreased in the deep
zone along the river, perhaps because of infiltration from the river.

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Page 31
Order-of-magnitude fluoride loadings co che Columbia River can be
calculated using che groundwater flow estimates presented earlier and the
concentration data described above. Loading estimates can be based upon
different assumptions regarding plume vidth and plume concentrations. In
areas closer to the source, Che plume vidth would be smaller and che plume
concentration would be higher. Away from the source, the width would tend
to Increase and the concentration would tend to decrease. Ideally, loading
estimates should be very similar for all locations.
For the shallow zone, the groundwater flow was estimated to be 60 cfd.
Assuming an average concentration of 200 ppm, results in a dally loading to
the Columbia River of approximately 1 pound per day fluoride.
Flow in the Intermediate zone is primarily vertical. The daily loading to
the deep zone is estimated to be approximately I pound per day. This is
based on a groundwater flow rate of 20 cfd and an average fluoride
concentration of 800 ppm.
The approximate fluoride loading for the deep zone is i pound per day.
This is based on the assumption that the average fluoride concentration in
the plume is 50 ppm and that the plume is 250 feet wide and 40 feet thick.
Flow in the deep zone discharges into the Columbia River.
Theoretically, the loading to the Columbia River from the deep zone should
equal che loading to che deep zone from the incermedlace zone. The
observed difference, i pound versus I pound, is due co the approximations
inherent in che estimates.
Cyanide Concentrations and Cyanide Loadings
The spacial discrlbutlons of cotal cyanide in the vicinity of the waste
piles are included on Figures 20 through 45. The soil concentrations are
based upon samples collected from soil borings completed during monlcorlng
well installation activities in August and September 1986. The water

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Page 32
concentrations are based upon analyses performed on samples collected In
November 1986 and March 1987.
The soil cyanide concentration data for the shallow zone. Figure 26, shows
that the primary area of contamination Is south of the piles In Che direc-
tion of the Columbia River. The groundwater concentration data for the
shallow zone, shown on Figures 20 and 22, show contamination south toward
the river and west toward the low spot In the original site topography.
The total cyanide soil and groundwater concentration data for the Inter-
mediate zone, shown on Figures 26, 28, and 30, Indicate downward migration
of cyanide from the dredged sands Into the silts and clays. As Is the case
with fluoride, the cyanide also becomes concentrated within the slit zone.
The cyanide concentration data for soil in the deep zone, shown on Figure
38, shows little contamination outside the immediate vicinity of the waste
piles. The data for groundwater in the deep zone, shown on Figures 34 and
36, show a relatively narrow plume flowing toward the Columbia River.
The cyanide data for the aquifer zone, shown on Figures 40 and 42, show
very little contamination. The highest concentrations are along the
Columbia River.
The data shown on Figures 20 through 45 are summarized on the cross
sections presented on Figures 46 and 47.
Figure 46 is based on soil concentrations from samples collected during
monitoring well installation in August 1986 and Figure 47 is based on
groundwater concentrations from samples collected in November 1986.
The groundwater concentration data can be used to infer the present extent
of the plume while the soil concentration data provide information on the
past extent of the plume. The contaminant plume appears to be moving south
coward the Columbia River. The portion of the plume that Is north of the
pile Is likely a result of infiltration that flows in the dredged sand

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along che surface of the silt materials. Contaminant discharge to the
Columbia River occurs primarily along the shore and not In the main channel.
Order-of-magnitude cyanide loadings can be calculated using the groundwater
flow estimates presented In the previous section and the concentration data
that are Included on Figure 47. For the shallow zone, the groundwater flow
was estimated to be 60 cfd. Assuming an average concentration of 20 ppm
results in a dally loading to che Columbia River of approximately 0.1 pound
per day total cyanide.
Flow in the intermediate zone is primarily vertical. The daily loading to
the deep zone is estimated Co be approximately 0.1 pounds per day. This is
based on a groundwater flow rate of 20 cfd and an average total cyanide
concentration of 80 ppm.
For the deep zone, in which the contaminated groundwater flow is estimated
to be 155 cfd, the approximate cyanide loading is 0.1 pound per day. This
Is based on the assumption that the average cyanide concentration in the
plume is 10 ppm and that the plume Is 2S0 feet wide and 40 feet thick.
Flow In the deep zone discharges into the Columbia River.
The loading estimates that we have calculated are very approximate. Large
uncertainties are associated with both the groundwater flow rates and the
contaminant concentrations. Ve have tended to be conservative in
estimating concentrations and therefore our estimates of contaminant
loadings are likely high.
Although the total cyanide data provide valuable information regarding
groundwater flow directions, from the point of view of health and safety
and environmental concerns, the contaminant of most Interest is free
cyanide. Cyanide in the groundwater at che Alcoa sice may exist as free
cyanide (cyanide ion or hydrogen cyanide), simple cyanides (e.g. potassium
cyanide, thlocyanate) and complex cyanides (metallic complexes). Free
cyanides are of most concern with regard to toxicity.

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Page 34
Tables A-8, A-ll, A-12, and A-13 present free cyanide data for Che
monitoring wells ac Alcoa. Free cyanide analyses vere performed on all
samples collected In September 1986 and for selected samples collected in
January, February, and March 1987.
The recognized method for determining the concentration of free cyanide in
groundwater is the micro-diffusion method, A5TM method 4282-83. This
technique is used by Century West Laboratories and the Alcoa Pittsburgh
Central Analytical Laboratory.
Groundwater samples have also been analyzed to determine the amount of weak
add dissociable cyanide, the amount of cyanide amenable to chlorinaclon,
and the amount of cyanide that Is photodegradable. The results are
prescribed in Tables A-14 and A-15. The results Indicate that very little
of the cyanide in the groundwater at the Vancouver site Is weak acid
dissociable, amenable to chlorlnation. or amenable to photodegradatlon.
This limits the type of treatment technology that Is applicable to the site
conditions.
The U.S. EPA'a revised ambient water criteria for free cyanide is 3,700
parts per billion (3.7 ppa) (49 FR 4551, February 1984). The highest
observed concentrations of free cyanide In the groundwater at the Alcoa
site are in monitoring wells completed In the intermediate zone. The
highest concentrations observed Is 1.1 ppm at MW-33B.
The concentration of free cyanide in the groundwater at the Alcoa Vancouver
site has generally been less than one percent of the total cyanide
concentration. The average ratio of free cyanide to total cyanide is 0.5
percent in the intermediate zone and 0.2 percent in the deep zone. These
values are based on samples analyzed from September 1986 through March 1987.
Our estimates of loadings Into the Columbia River for total cyanide are 0.1
pound per day for the shallow zone and 0.1 pound per day for the deep zone.
Assuming an average free cyanide concentration of 0.5 percent of total cya-
nide results In a free cyanide loading of approximately 0.001 pound per day.

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«J— 1759—02
Page 35
Concentration Variability
Duplicate and triplicate groundwater samples were collected to evaluate
analytical variability. Duplicate samples were submitted to Century Ue9t
Laboratories to evaluate variability within the laboratory and triplicate
samples were submitted to Alcoa Vancouver Laboratory to evaluate
variability between laboratories. The results of the duplicate analyses
are summarized in Table A-16. The error presented on this table is a
measure of how closely the analysis results could be replicated. It is
presented in percentage. For example, an error of 30 percent means that
the difference in concentrations between two duplicate samples is plus or
minus 30 percent.
The average error for cyanide is 18 percent. The average error for fluoride
is 24 percent. A large portion of these errors are due to three samples:
MW-10 on 9/18, MV-7 on 12/86, and MW-3QA on 2/87. If these three outliers
are rejected, the average error for cyanide is 8 percent and the average
error for fluoride is 12 percent.
Tables A-17 .and A-18 in Appendix A present summaries of statistical
analyses on cyanide data (Table A-I7) and fluoride data (Table A-18). The
analytical variability presented in these tables Is a measure of how
closely the results of analyses made by Alcoa Vancouver Laboratory match
the results of analyses made by Century West Laboratory. It is presented
in percentages. For example, an analytical variability of 0.35 means that
the difference In concentrations between the Century Uest results and Alcoa
Vancouver results is plus or minus 35 percent.
The average analytical variability for September 1986 through March 1987
was 0.35 for cyanide and 0.22 for fluoride. The analytical variability
tended to decrease with time for both constituents.
The analytical variability can be compared with the total variability. The
total variability is due to both analytical variability and fluctuations in
concentration with time. The rlght~hand columns in Tables A-17 and A-18

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Page 36
compare analyclcal and cotal variability. The cocal variability is measured
in terms of the coefficient of variation, which Is Che raclo of che standard
deviation divided by Che mean value. Ic is also a percentage. By sub-
tracting che analyclcal varlabillcy from che toCal variability, che "real"
fluccuacions due co changes in concencraclon with clme can be assessed. For
example, at monicorlng well 26 che average analyclcal varlabillcy is 1.02
andche total variability is 1.11. Fluctuations due to changes in
concencraclon wlch clme are relatively small. At monitoring well 17, the
average analytical variability Is 0.11 and the total variability is 2.16.
At this location, fluctuations due to changes in concentration with time
are qulce large.
Possible ConCaminanc Receptors
Two general receptors of contamination from che waste piles have been
Identified: water wells located in the vicinity of the Alcoa plant and the
Columbia River. The locations of water wells on the plant are shown on
Figure 3. There are three domestic wells within a one mile radius of the
plant. These wells, which are all less than 100 feet deep, are shown
Figure 48. Three City of Vancouver municipal wells are locaced between
Chree and four miles northeast of the site (see Figure 2). The existing
wells are upgradlenc of the waste piles. The likelihood of contamination
migrating from the waste piles to the municipal or domestic wells is
remote. The Alcoa production wells will tend to capture any contaminants
that enter che aquifer in the vicinity of the waste piles.
The production wells immediately north of the waste piles are monitored on
a monthly basis for total cyanide. The results of these monitoring
activities are included in Appendix D. Well PW-15 Is the only production
well that has shown total cyanide concentrations above several parts per
billion. The average concentration in PW-15 was 0.011 ppm in 1984, 0.011
ppm in 1985, and 0.010 ppm in the first five months of 1986.
Water samples from the water supply system at Alcoa-Vancouver are also
periodically monlcored for mecals, organlcs, cocal dissolved solids, pH,

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Page 37
alkalinity, hardness, curbldlcy, and total colifonn. The results of these
analyses show that the water meets federal drinking water standards.
The second general receptor is the Columbia River. The average discharge
in the Columbia ac Vancouver is approximately 200,000 cfs. The very large
discharge in the Columbia River would greatly dilute any contamination.
Measurements of cyanide and fluoride concentration in the Columbia River at
Alcoa have shown concentrations less than 0.005 ppm and 0.15 ppm,
respectively. These equivalent to background concentration.
ENVIRONMENTAL EFFECTS ASSOCIATED WITH CYANIDE AND FLUORIDE
The following section presents a summary of the potential environmental
impacts and effects upon possible receptor systems which have received
cyanide and fluoride discharges in the vicinity of the waste piles at the
Alcoa site. A more detailed evaluation is Included in Appendix F.
The environmental effects are discussed in terms of three ecological units:
atmosphere, llthosphere, and hydrosphere. A generalized overview of
potential environmental receptors for cyanide (and its various chemical
species) and representative reactions and interrelations within and between
receptors is preseneed on Figure F-l. While differing In specifics,
comparable pathways and reactions (particularly those Involved with
comlexatlon and sorption) would exist for fluoride.
Atmosphere
Volatilization of cyanide (as HCN) and decomposition by-products such as
ammonia are well known and constitutes a significant pathway of loss
through diffusion and dispersion. Ammonia odors were noted during drilling
and digging activities on the waste piles. These odors imply that
hydrolytlc and possibly oxidative processes are actively decomposing
materials within the waste piles.

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Page 38
Fluoride, the 13eh mosc abundant element, occurs naturally In the atmosphere
in the form of Insoluble particulates and soluble gases (HF, organofluo-
rldes, silicon tetrafluorlde, etc.). These derive from a variety of natural
sources including volcanlsm and weathering and entralnment of mineral soil
particles. Concentrations are typically less than 5 micrograms per cubic
meter but sources associated with industrial activity (e.g., combustion of
coal, production of hydrogen fluoride, steel, aluminum, and production of
phosphate fertilizers) can lead to substantially higher localized atmos-
pheric concentrations. This would Imply the possibility for increased
levels of atmospheric fluoride in the Immediate vicinity of the site, but we
are unaware of any past or present information which would substantiate this
Implication.
No environmental risk from gas generation within the piles is perceived.
The piles are in a well-ventilated area and ammonia odors are only
noticeable a few Inches from the pile surface.
Llthosphere
The results of soil cyanide sampling at the site are presented in Table A-2.
These data indicate that there appears to be little cause for concern
related to the soil cyanide concencraelona observed. Cyanides at moderate
concentrations are subject to active biological uptake and microbial attack
and may subseltute or act as fertilizers at concentrations up to 200 ppm
(Fuller, 1985). However, cyanides that are complexed with iron are not
readily degraded by microbial or biological processes. Indications of
accumulation within the Intermediate zone imply gradual release rates and
extended periods of time for removal through dissolution to the groundwater.
Fluoride Is a natural constituent of soils and occurs over a wide range of
concentrations dependent upon the nature of parent rock materials and other
sources of Input. Minerals soils average 200 to 300 ppm fluoride with
sandy soils tending to contain less than the average and finer grained,
organic and phosphorus rich soils containing above average concentrations

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Page 39
(7000 to 8000 ppo In extreme cases). The most common fluoride minerals are
fluorspar (CaF^) and fluorapatlteCCaF^ 3^3
Fluoride Is considered to be persistent In most soils, being strongly
absorbed by colloids and not easily displaced by anions. Relatively
Insoluble calcium salts and aluminum slllcofluorldes are predominant forms.
The results of the sampling for soil fluoride analysis are presented in
Table A-2. With the exception of Isolated hot spots within the shallow and
Intermediate zones, concentrations are fairly low. The Isolated hot spots
are most likely related to the presence of relatively Insoluble fluoride
minerals such as fluorspar and cryolite ONaFAlF). As with cyanide, there
Is no indication of significant accumulation within the deeper geohydrologlc
units.
Hydrosphere
The chemistry of cyanide and its various forms in aqueous solution is
complex. In general, under ambient circumneutral pH, cyanide will exist In
equilibrium between hydrogen cyanide (HCN), cyanide ion (CN-), and simple
alkali-metal cyanides. Hydrogen cyanide will predominate except In metal
complexes. Conplexed metallocyanides (particularly complexes of those
instances where dissociation favors Che formation of more stable iron) are
more stable, will persist and most often account for the majority of
residual cyanide.
Analytical distinction between easily dissociable cyanides ("free cyanide")
and complexed cyanides Is possible and has been evaluated for selected
samples taken from the site. The results indicate that the majority of the
cyanide present within these samples was in the form of the more stable
complexed cyanides (approximately 99 percent). Based upon past experience
with comparable aluminum sites in other locations, iron cyanides would be
the single most important complex found (Century West Laboratories,
personnel communication). This is significant from the standpoint that
toxicity associated with cyanide Is generally related to the "free cyanide"

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Page 40
fraction, specifically HCN, and the race at vhlch more complex species
contribute to this fraction.
Iron cyanides are among the more stable complexes of cyanide and under con-
ditions ac the site would not be expected to contribute substantially to
the "free cyanide" fraction. It is generally believed that they are subject
to photolytic decomposition and may contribute "free cyanides" under the
appropriate exposure conditions. However, the results of analyses completed
by Alcoa to determine the concentration of photodegradable cyanides (Table
A-14) ac Che Vancouver site show litde cyanide Is phocodegradable.
Iron cyanides have a demonstrated salaonld toxicity (rainbow and brook
crouc) apart from thac attributable to "free cyanide" but Che lethal doses
(96 hr	range from 750 Co 1200 ppm (Hemlng and Thurston, 1984), far in
excess of any concentration anticipated for discharge to receiving waters
within Che vlclnlcy of Che site.
Fluorine, che most eleccronegaclve of all elements, la highly reactive and
rarely occurs in elemental form (F^). Ic Is however abundant and widely
dlscrlbuced In ionic and combined forma In aqueous solutions. Ionic
fluorides resulc from Che reaction of fluorine with metallic elements to
form both soluble and insoluble salts (alkali and alkaline earth metals)
and complexes wlch heavy metal polyvalent cations (e.g., iron, aluminum,
manganese). Fluoride may also exist as covalently bonded compounds (com-
plexes with oxygen, sulfur, silicon), organofluorldes, and halofluorldes.
The majority of these are highly volatile and soluble In aqueous solution.
As indicated previously, mineral fluorides (fluorspar, fluorapaclte and
cryolite) are essentially Insoluble in water.
Fluoride is a normal constituent of surface and groundwaters. Vacootaal-
naced surface freshwater concentrations average about 0.3 ppm and saline
waters range from 1.5 (marine) up to 14 ppm (Great Salt Lake). Groundwater
concentraclons are dependent upon parent rock materials and are usually
less Chan 10 ppm buc may reach values (uncontaainated) of 60 Co 70 ppm.

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Page 41
Groundwater fluoride concentrations measured within the vicinity of the
site indicate that ambient, uncontaminated concentrations would be fairly
low relative to reported average groundwater fluoride and that significant
contamination has taken place within Isolated areas of the site. The high
concentrations observed would preclude the use of the groundwater for
domestic use.
The hydrogeologlcal analysis presented earlier demonstrates that the
predominant groundwater flow is toward the Columbia River and, as such,
the river would appear to be the only major ecological receptor associated
with the site. Impacts related to predicted loadings and resultant
concentrations In the Columbia River are discussed below.
Columbia River Impact Evaluation
Priority Pollutants
Low concentration levels of several priority pollutant organic chemicals
and metals were detected In several groundwater samples. Methylene
chloride, acetone, and Bis(2 methylhexyl)phthalate concentrations are
considered to be likely the result of laboratory contamination. Several
other chemicals were detected at relatively low concentrations but with no
evident pattern. The 20 ppb of trlchloroethylene detected in one of the
aquifer mils Is considered to be highly suspect.
Several of the metals exceed EPA fresh water criteria. Generally the
highest metal concentrations were detected in the relatively low
permeability Intermediate zone.
Based on the observed concentrations of organic chemicals and metals in
groundwater and on the hydrogeologic conditions it unlikely that any of
these constituents would be detectable In the river above background
concentrations.

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Page 44
are below EPA criterion values, the average concencracion of fluoride in
wells completed in che deep zone near Che river is approximately S mg/L.
The fluoride concentration in groundwater entering the river is likely less
than this value. Any adverse effects, if present, would occur over a very
small area. Samples taken from the river during the course of this
investigation indicate no difference between upstream and downstream
concentrations. These were surface grab samples however and would have no
bearing upon possible microzone differences at Che sediment water
interface. Impacts upon the Columbia River associated with the discharge
of groundwater containing cyanide and fluoride would appear to be
nondetectable relative to water column concentrations and minimally
localized, if at all, to areas of groundwater seepage.
HART CROWSER, INC.
^CyYV\jQ/YV^
JOEL W. MASSMANN, Project Manager
Project Engineer
MATTHEW G. DALTON
Senior Associate
MGD/JWM:sea

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Aluminum Company of America
Mining Waste NPL Site Summary Report
Reference 2
Excerpts from the Feasibility Study, Potlining Waste Piles,
Aluminum Company of America, Vancouver Operations;
Prepared for ALCOA by Hart Crowser;
July 27, 1987

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HARTCROWSER
Earth and Environmental Technologies
Feasibility Study
Potlining Waste Piles
Aluminum Company of America
Vancouver Operations
Vancouver, Washington
Prepared for
Aluminum Company of America
July 27, 1987
J-1759-02
19 to Fairview Avenue East Seattle. Washington 98102-3699 206 324 9530

-------
Generalized Hydrogeologic Units
B
I
£
40
o
®
c
o
a
>
to
Ui
-40
-00
•120 L
Ground Surface
|) SILT with SAND^and CLAY lenses Clnlermediale Zone)
Dredged SAND
(Shallow Zone)
Fine to medium SAND (Deep Zone)
Sandy GRAVEL (Aquifer Zone)


x
%
o
*
MW-18
PW-15
(60' W)
o>
O
Note: Stratum line* arc baaed upon Interpolation between explorations and
represent our Interpretation ol aubaurlace oondltlona baaed on
currently available data.
Monitoring Well Number
Production Well Number
Offset Distance and Direction
Well Location
H
Vertical Exaggeration x 5
Horizontal Scale In Feet
0	200	400
o=^=3""™^SP======bo
Vertical Scale in Feet

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Site and Exploration Plan
Aquifer Zone
O
•
189 Aquifer Zone
Monitoring Well
Location and
Number
&ac
0 Slraal
C Slreal
8 Sireei
© 2 IB
O o
—J
Shoreline
250
S00
COLUMBIA RIVER
n o
Scale in Feel

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Potentiometric Head Elevation Contour Map
Shallow Zone October 1986
E Street
* 24.57
* DRf
18.50
C Street
• DRY
* DRY
• DRY	• DRY
DRY
~ DRY
DRY •
• DRY
COLUMBIA RIVER
t
18.43
18
Flow Direction
Spot Potentiometric Head
Location and Elevation in Feet
Potentiometric Head
Elevation Contour in Feet
October 23, 1986
250
500
Scale in Feet
J-1759-0 2 June	1987
HART-CROWSER & associates inc.
Figure 18

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Potentiometric Head Elevation Contour Map
Shallow Zone May 1987
F Stiaal
E Slroal
Flow Direction
<918.50 Spot Potentiometric Head
Location and Elevation in Feet
/
4.8 Potentiometric Head
Elevation Contour In Feet
May 1987
20.97 a
22.650,'
®2 1.36
21.14
® 20.88
Strati
©19.70
19.82

14.85
00.00
© 7.86
07.99
Shorallna
COLUMBIA RIVER
Scale In
Feel

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J-1759-02
Page 2
1.2	Project Background
The ALCOA Vancouver operations are located approximately 2.5 to 3.0 miles
vest of Vancouver, Washington, immediately adjacent to the Columbia River
(Figure 1). The facility was constructed in 1939 and 1940 and started
operations in late 1940.
The ALCOA Vancouver operations primarily consist of an aluminum reduction
plant vith associated support facilities. The facility produced aluminum
using the Hall-Heroult electrolytic cell process. As part of this process,
a waste material was produced consisting of spent potlining (SPL) and
reclaimed alumina insulation (RA1). This material contains cyanide and
fluoride, which are the constituents of primary concern.
The aluminum reduction process occurs in a cell or pot which typically
"fails" every three to five years. After a pot failed, the waste materials
(SPL and EAI) were removed from the poc and transported to a handling area
located within the southeast portion of the plant (Figure 2). Prior to
1973 and after 1981, the waste was removed off site. Waste produced
between 1973 and 1981 still remains on-site in three piles.
A Remedial Investigation (RI) was conducted by Hart Crowser, Inc. under
contract to ALCOA to assess the nature and extent of the water quality
conditions in the vicinity of the waste piles. These data indicate that
constituents present in the waste piles have leached from Che piles and
have entered the groundwater system but pose no threat to any drinking
wacer supply. The daca are summarized in Che final RI report for the sice
(Hart Crowser, Inc., 1987). A brief summary of the site conditions,
potential receptors, and environmental risk is presented in subsequent
sections of this report.
1.3	Summary of Reports and Available Data
An extensive amount of field exploration, field sampling, and cechnical
analyses have been completed at the site. Soil samples were taken from

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J-I759-02
Page 3
borings and analyzed for cyanide in che vicinicy of Che vasce piles in 1972
(Haisch. undated). Monitoring veils were installed in 1977 (Robinson,
Noble and Cart, Inc., 1981), and in 1980, 1981, and 1984 (Robinson, Noble
and Carr, Inc., 1981 and 1982; and Robinson and Noble, 1984).
Since 1982, ALCOA has conducted a monitoring program at che Vancouver
site. This program Included measuring vacer levels and collecting
groundwater samples from each monitoring veil on a monthly basis. The
groundwater samples were analyzed for cotal cyanide. Selected samples were
analyzed for free cyanide.
A preliminary assessment of the groundwater conditions vas compleced by
Hare Crovser in 1986. The results of this assessment are documented in a
report titled "Preliminary Assessment of Groundwater Quality Conditions,
Aluminum Company of America, Vancouver Operations. Vancouver, Washington"
dated August 1, 1986.
Based on che preliminary assessment, additional sampling and analysis work
was recommended. The results of the initial phase of this work is
documented in an interim report prepared by Hart Cromer, Inc. (1987).
Since preparation of the interim report, additional sampling and analysis
have been completed. This vork and associated analyses and findings are
documented In a Final Remedial Investigation Report prepared by Hart
Crowser, Inc. in July 1987.
1.4 Summary of Existing Conditions
1.4.1 Waste Pile Characterization
Approximately 66,000 tons of waste materials were reported by ALCOA to
remain on-site in the three piles shown on Figure 2. About 10,000 of these
tons are scored in the RAI pile (Pile Mo. 2); 48,000 tons are in the first
poclinlng pile (Pile No. 1); and 8,000 cons are In che second poclining
pile (Pile No. 3). This estimate was based on converting the volume of

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waste into coos assuming that che waste bulk unic veight is about 100
pounds per cubic foot. Based on our pile sampling activities, we believe
that a more representative bulk unit veight is on the order of 120 pounds
per cubic foot. Using this latter figure and somewhat differing
assumptions regarding waste volume, we estimate that about 75,000 tons are
contained in the piles.
While no detailed waste pile sampling was conducted, the approximate
composition of these piles can be estimated based upon knowledge of the
composition of typical fresh spent potliner material. Spent potlining is
generally composed primarily of carbon, fluoride, sodium, aluminum,
silicon, iron, and calcium. These seven constituents are generally present
in amounts greater than 1 percent. Trace amounts of aluminum nitride,
aluminum carbide, cyanide, sulfur, and phosphorous may also be present.
The constituents that causes the most environmental concern Is cyanide.
The average amount of cyanide in the potlining is la the range of 0.03 to
0.5 percent. The actual cyanide concentration can be only a few parts per
million or as much as several percent, depending upon Che location in the
pot.
Leaching tests using the EP toxicity procedure Indicate that samples of
fresh potlining would not be classified as a dangerous waste based on
metals concentrations. The leachate that was generated from the procedure
was very alkaline and contained cyanide.
Fish bioassay testing of the same samples determined that the fresh
potlining produced at ALCOA's facility is classified as an extremely
hazardous waste under Washington State regulations. Potlining is currently
exempt from RCRA listing as a hazardous waste. This status may change in
the future.
In 1978 the wastes stored on the ALCOA site were graded, formed into two
piles and covered to prevent precipitation from contacting the waste and
causing contaminants to migrate to the water table. The cover system

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consists of a 12 mil PVC synthetic membrane placed between two L2- to 18-
inch-thick layers of sand. Vegetation vas placed over the final cover.
The third waste pile vas covered in 1981.
During the Remedial Investigation the integrity of the covers vas assessed
by visual observation. At several locations along the sides and top of the
pile the liner vas torn and liner seams were separated. Ammonia-like odors
vere detected at these locations. At other locations the cover material
vas in good condition.
Our observations also indicate that the covers do not extend past the toes
of the piles and that some potlining is not covered. Surface drainage from
the covers likely infiltrates into these wastes along at least a portion of
the pile edges. The amount of infiltration along tears and seams is likely
of secondary importance vhen compared to the amount of infiltration along
the uncovered pile edges.
1.4.2 Geology
Geologic samples obtained during drilling on the site indicate that the
materials within the depth of drilling can generally be divided into four
geologic units.
o Shallow Zone: A perched groundwater zone lies within dredged sand
materials. The dredged sand is approximately 10 feet thick. The
bottom 2 Co 3 feet are Intermittently saturated, depending on location.
o Intermediate Zone: The intermediate zone lies beneath the dredged sand
and is composed of relatively low permeability sandy silt and silty
sand. It is about 30 to 40 feet thick. The top of this unit formed
the natural ground surface prior to placement of the dredged sand.
o Deep Zone: The deep zone lies beneath the intermediate zone and is
about 40 feet thick. The top of the zone lies at a depth of about 45
feet. The deep zone is composed of fine to medium sand.

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o Aquifer Zone: -The aquifer zone Is the deepest zone penetrated by
drilling, the top of which lies at a depth of about 100 to 120 feet.
This zone is composed of coarse sand and gravel and is the major
aquifer in the area.
1.4.3 Hydrogeology
The predominant groundwater flow direction beneath the waste pile area is
toward the Columbia River. The shallow zone is intermittently saturated
depending on location. Some minor groundwater flow may occur to the
northwest within a topographically low area which defines the bottom of the
shallow zone. The available data indicate that migration to the northwest
is limited.
Flow within the intermediate zone is predominantly downward toward the deep
zone. This zone is of relatively low permeability (I0~^ to 10~^ cm/ sec).
However, a very steep downward vertical hydraulic gradient exists between
the Intermediate and deep zone (on the order of 0.6).
Groundwater flow in the deep zone is predominantly toward the river. Water
levels in this zone fluctuate in response to river fluctuations. This zone
Is recharged from the overlying intermediate zone.
The major aquifer zone overlies the deep zone at a depth of 100 to 120
feet. Vater levels in Che aquifer zone fluctuate in response to the
pumping of ALCOA production wells and to the Columbia River. The relative
response of Che aquifer and deep zones to well pumping indicates that the
zones are hydraullcolly separated.
1.4.A Vacer Quality
The available data indicate that cyanide and fluoride concentrations in
groundwater are of greatest concern. Low concentrations of several
priority pollutant organic chemicals and metals were also detected. The

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Page 7
range of groundwater concentrations of selected constituents is summarized
belov:
PH
electrical conductivity (micromhos)
total cyanide (mg/L)
free cyanide (mg/L)
fluoride (mg/L)
5.1 to 10.0
150 to 11,000
L/.005 to 400
L/.005 Co 1.1
L/2.0 to 1,200
volatiles (mg/L)
below detection to 0.150
base, acid, neutral
exctractables (mg/L)
pestlcldes/PCB (mg/L)
below detection to 0.039
below detection to 0.0001
1.4.5 Water Supplies
The CiCy of Vancouver operates several municipal wells	three to four miles
east of the ALCOA facility. The locations of these	wells are shown on
Figure 1. The nearest well is located on a terrace	approximately three
miles from the waste piles.
Several industrial water supply wells are located immediately north of the
waste piles (Figure 2). The veils provide water for the ALCOA plant. Most
of this water is used for non-contact cooling purposes. The wells are
screened in the aquifer zone beneath the site approximately 100 to 140 feet
belov ground surface. They are generally operated three at a time and
withdraw about 4 to 5 million gallons per day.
Three domestic wells exist within approximately one mile of the plant
site. The approximate locations of the veils are shovn on Figure 1. The
wells are less than 100 feet deep and are located upgradlent from the waste
piles. The locations and depths of the wells prevent them from being
Impacted by groundwater contamination in the vicinity of the waste piles on
the Alcoa Vancouver site.

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1.4.6 Utilities
Several burled utilities are present near and beneath the piles as shown on
Figure 2. These include a 2-inch-diameter potable water line, an 18-inch-
diameter sanitary sever, a 14-inch-diaaeter water main, and a 42-inch-
diameter industrial sever line. The 14-lnch-dlameter water main is used to
supply water to fire hydrants. A television inspection of Che 18-inch cast
iron sewer line belov the waste piles was conducted by CELCO of Salem,
Oregon in 1985. Their results, summarized in a report dated October 23,
1965, concluded that the line vas in good condition, the grade flat, and
the alignment straight. Some sand was observed along the bottom of the
pipe.
1.5 Receptors and Environmental Risk Assessment
Surface Waters
The hydrogeologic and water quality assessment indicates Chat the primary
receptor of site contamination is the Columbia River via a groundwater
migration pathvay. The constituents of primary concern are cyanide and
fluoride. The risk assessment indicates that the adverse environmental
effects to the river are negligible.
Groundwater
Groundwater beneath the site has been contaminated by leaching of waste
pile constituents, especially cyanide and fluoride. The hydrogeologic
assessment Indicates that existing drinking water supplies are not
threatened by contaminant migration. Because of Che location of Alcoa's
production veils, they could be used Co Indicate any fuCure groundwater
problems before contaminants would occur in drinking water veils. However,
the risk of contaminating Alcoa's production veils Is considered low.

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Page 9
Airborne Emissions
o In their currenc state, the waste piles do not appear to be a source of
dust. The large majority of the waste materials are covered with a PVC
liner and a 2-foot-thick. layer of sand. Along the toe of the piles the
PVC liner is missing but the materials are still covered with sand. We
do not consider control of dust to be a remedial action objective.
o The piles are generating gases with an ammonia odor. Ammonia odors are
only noticeable within a few inches of Che pile surfaces where the
existing PVC liner is separated or ripped. The piles are located in a
well-ventilated area. Gas emissions will need to be considered in
evaluating remedial alternatives but gas control is not considered to
be a remedial action objective.
1.6 Remedial Action Objectives
The remedial action objectives are based on our evaluation of potential
receptors and assessment of environmental risk. Based on these evaluations
the primary remedial action objectives are to:
o Minimize the generation of leachate and the migration of contamination
to the water tabic.
o Reduce contaminant migration into the Columbia River.
2.0 APPROACH TO DEVELOPING AND EVALUATING REMEDIAL ACTION ALTERNATIVES
The approach used to develop and evaluate remedial action alternatives is
graphically shown on Figure 3. Development and evaluation of remedial
action alternatives was generally approached using EPA guidelines.
Specifically this included:

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Page 35
distribution of groundwater contamination. No increases In the public
health risk are identified.
4.1.3	Institutional Issues
Groundwater monitoring is generally required by federal and state agencies
at sites such as the ALCOA facility.
4.7.4	Cost Analysis
Costs associated with groundwater monitoring include capital costs for
installing wells and annual coses for collecting and evaluating groundwater
samples. The capital costs are small relative to annual costs. For the
purpose of evaluating costs, we have assumed 20 existing monitoring wells
will be sampled four times each year for 30 years. The samples will be
analyzed for pH, electrical conductivity, fluoride, and total cyanide. We
have assumed that most of the 20 monitoring wells will be selected from
existing locations. The annual monitoring costs for this level of effort
is estimated to be $20,000. The present value of $20,000 per year for 30
years assuming a 5 percent discount rate Is approximately $310,000.
4.7.5	Effectiveness
Groundwater monitoring Is an effective and recommended remedial action
component.
5.0 DEVELOPMENT AND EVALUATION OF REMEDIAL ACTION ALTERNATIVES
Section 4 described specific components of remedial action alternative.
One component by Itself typically would not be sufficient to provide the
level of performance required to mitigate the environmental concerns. In
this section, the preferred components are combined in various ways such
that a range In levels of protection as well as a range In associated costs
are presented and discussed. The alternatives are divided into three broad

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categories: 1) continued groundwater monitoring (no action), 2) on-site
containment, and 3) remove source from site (landfill or treat).
5.1	Continued Groundwater Monitoring
o Description: This alternative involves no action other than to
continue monitoring and testing groundwater samples using existing
wells.
o Advantages: Costs are significantly less than any other option. The
potential for public exposure to the pile material by excavation and
moving is not present.
o Disadvantages: Containment or removal of source material is not
accomplished. Additional generation of leachate and subsequent
Infiltration Into groundwater is likely, although under the existing
conditions, there Is likely no measurable Impact on the Columbia River
and the potential to contaminate pulic water supplies 1s remote.
o Estimated Cost: $310,000 (present worth)
5.2	Contain Source On-Slte
5.2.1 Earth Cover with Site Grading'
o Discription: The waste piles will be covered with an earth cover
composed of clay/sand. The site will be graded and surface water
diverted off-site via lined ditches, culverts, and below-ground
drains. The portion of the existing railroad will be moved 30 feet
south. Groundwater monitoring will continue.
o Advantages: Conventional technology and construction techniques.
Prevents Infiltration Into waste piles and reduces infiltration around
waste piles. Durable. Water ponding along railroad tracks and streets
will be eliminated* Equivalent to pile removal but at lower cost.

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o Disadvantages: Will allow some infiltration outside the waste pile
area into underlying contaminated groundwater. Source of contamination
remains in place. No treatment of contaminated groundwater.
o Estimated Cost: $1,360,000
5.2.2 Earth Cover with Site Grading and Paving
o Dlscrlption: The waste piles will be covered with an earth cover
composed of clay/sand. The site will be graded and surface water
diverted off-site via swales in the asphalt pavement, culverts and
below-ground drains. The site surrounding the waste piles including
roads in the vicinity, will be paved with asphalt. The pavement would
be capable of supporting moderately heavy truck traffic. Groundwater
monitoring will continue.
o Advantages: Conventional technology and construction techniques.
Prevent infiltration below the piles as well as the surrounding area.
Roads in area will be paved. Should reduce loading to the Columbia
River. Area can be used for storage of moderately heavy loads.
o Disadvantages: Source of contamination remains in place. Higher cost
of paving with only a small gain in public environmental/health benefit.
o Estimated Cost: $1,680,000
5.2.A Earth Cover with Site Grading, and Pumping and Treating Groundwater
o Description: The waste piles will be covered with an earth cover
composed of clay/sand. The site will be graded and surface water
diverted off-site via lined ditches, culverts, and below-ground pipes.
Contaminated groundwater would be pumped from wells Installed to about
80 feet In depth and treated. Sludge from the treatment could be
disposed in a landfill. Treated water would be disposed Into the
Columbia River. Groundwater monitoring will continue.

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o Advantages: Loadings Co the Columbia River would decline via
groundwater migration by reducing precipitation infiltration in
contaminated area due to site grading and removing contamination in
groundwater in the deep zone by pumping and treating.
o Disadvantages: Costs for such a system are relatively high and source
remains on-site. Loadings to the Columbia River would Increase during
pumping if treated water is discharged to the river. Residual from
water treatment would need to be disposed of in a landfill.
o Estimated Cost: $3,610,000
5.3 Remove Source from Site
5.3.1	Dispose in Landfill and Grade Site
o Description: Waste material would be excavated and taken to Arlington,
Oregon. The site will be graded and surface water directed off-site
via lined ditched, culverts, and below ground drains. Groundwater
monitoring will continue.
o Advantages: Source material Is removed from site. Risk of additional
leachate generation is negligible. Surface water ponding is eliminated.
o Disadvantages: Costs are significantly higher than the cover options.
Potential risk of contaminated dust emissions during transport.
o Estimated Cost: $12,500,000
5.3.2	Dispose in Landfill with Site Grading and Paving
o Discussion: Waste material would be excavated and taken to Arlington,
Oregon. The site will be graded and surface water diverted off-site
via swales in asphalt pavement, culverts and below ground drains. The
entire site will be paved with asphalt, Including roads In the

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Page 39
vicinity. The pavement would be capable of supporting moderately heavy
truck traffic. Groundwater monitoring will continue.
o Advantages: Source material is removed from site. Loading to the
Columbia River is reduced by restricting precipitation infiltration.
Less risk of water ponding on site. Roads in the area would be paved.
o Disadvantages: High costs. Potential risk of contaminated dusc
emissions during transport.
o Estimated Cost: $13,000,000
5.3.3 Dispose Waste in Landfill with Site Grading, and Pumping and
Treating Groundwater
o Description: The waste material will be excavated and taken to
Arlington, Oregon. The site will be graded and surface water diverted
off-site via lined ditches, culverts, and below ground drains.
Contaminated groundwater would be pumped from wells installed to about
80 feet In depth and treated. Sludge from the treatment would be
disposed In a landfill. Treated water would be disposed into the
Columbia River. Groundwater monitoring will continue.
o Advantages: Source material removed from the site. Loadings to the
Columbia River via groundwater migration would be further reduced by
reducing Infiltration of precipitation through site grading and
removing contamination in groundwater In the deep zone through pumping
and treating.

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o Disadvantages: Very high costs over other alternatives. Potential
risk of contamination dust emissions during transport. Loadings to the
Columbia River would be increased during the required pumping term if
treated water is discharged to the river. Residual from water
treatment would need to be disposed of in a landfill.
Estimated Cost: $14,700,000
6.0 PREFERRED REMEDIAL ACTION ALTERNATIVE
Seven remedial action alternatives were developed based on evaluation of
remedial action components. Estimated costs to implement the remedial
actions range from approximately $300,000 to $14,700,000 as summarized
below.
Description	Estimated Cost
No Action
o Continued Groundwater Monitoring	$308,000
On-Site Containment
o Earth Cover with Site Grading	$1,360,000
o Earth Cover with Site Grading and Paving	$1,680,000
o Earth Cover with Site Grading, Paving, and
Groundwater Pumping and Treatment	$3,610,000
Waste Removal
o Waste Disposal In Landfill and Site Grading
$12,500,000

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o Waste Disposal in Landfill and
Sice Grading/Paving	113,000,000
o Waste Disposal In Landfill and
Sice Grading/Paving, and Groundwater Pumping
and Treating	$14,700,000
Based on the evaluations presented in Section 5.0, our preferred remedial
alternaClve consists of leaving the wastes ln-place, constructing an earth
cover and grading the site so that surface wacer drains away from Che pile
area (5.2.1). This alternative would meet Che remedial acclon objectives
of minimizing the generation of addlclonal leachate which in curn will
reduce cyanide and fluoride loadings co Che Columbia River.
Groundwater monitoring would also be conducced. This monitoring would be
directed covard Identifying changes in che wacer quallcy conditions and
confirming chac contamination Is noc migrating Co drinking wacer wells.
Covering Che wasce ln-place is considered Co have a similar public and
envlronmencal healch beneflc as removing che waste from Che sice. The cost
of covering is substantially lower (on che order of $10,000,000 lower).
Paving, alchough not very cosdy, would noc add subscancially Co reducing
leachace generadon or contaminant migration to che river assuming chac the
grading acclvicies are lmplemenced.
Groundwacer pumping and creacment would meec che remedial acclon objective
of reducing coneamlnate migration co Che river, and would speed groundwacer
cleanup co a degree. However, che hydraulics of che groundwacer syscem
beneach che wasce piles, and the nacure of the soils and contaminants
Indicate chac pumping would have Co occur for cens of years.
The creaced wacer would likely be discharged inco che Columbia River. Even
after treatment, the water chac is extracted from beneath the piles would
have higher concentrations of fluoride and cyanide than groundwater
presently discharging into the Columbia River. Pumping and creaclng would

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increase che mass loading to Che river while Che pumping system is
operaclng.
Given thac there appear Co be few, if any, adverse effects on che river
under existing conditions, pumping and treating is not considered to be
cost-effective. This remedial action component could be Implemented at a
later time based on che groundwacer monitoring daca.
HART CROVSER, INC.
DANIEL. V. MAGEAU, P.E
Project Engineer
MATTHEW G. DALTON
Senior Associate
DWM/JWM/MGD:taa

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Aluminum Company of America
Mining Waste NPL Site Summary Report
Reference 3
Excerpts from the Health Assessment for ALCOA (Vancouver Smelter),
Vancouver, Clark County, Washington; Agency for Toxic Substances
and Disease Registry, U.S. Public Health Service;
May 9, 1990

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ALCOA (VANCOUVER SMELTER)
VANCOUVER, CLARK COUNTY, WASHINGTON
CERCLIS NO. WAD009045279
MAY 9 )990
Agency for Toxic Substances and Disease Resistr
U.S. Public Health Service

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SUMMARY
The ALCOA (also-known as Vancouver Smelter) site, located on the northern
bank of the Columbia River about 4 miles west of Interstate 5 in
Vancouver, Clark County, Washington, has been proposed for the National
Priorities List. The site consists of three waste piles containing about
66,000 tons of waste (spent potlinings and alumina insulation) that were
deposited on the north bank of the Columbia River by ALCOA between 1973
and 1981. ALCOA has since sold the aluminum smelter to another company,
VANALCO. The contaminants detected in the groundwater in the area
surrounding the piles include cyanide, fluoride, and trichloroethene
(TCE). The ALCOA site is of potential public health concern because
humans may be exposed to hazardous substances at concentrations that may
result in adverse health effects.
BACKGROUND
A. SITE DESCRIPTION AND HISTORY
The ALCOA site, located on the northern bank of the Columbia River about
4 miles west of Interstate 5 in Vancouver, Clark County, Washington, has
been proposed for the National Priorities List. The three waste piles
that constitute the site are surrounded by the aluminum plant, which is
owned and operated by three companies, VANALCO, VANEXCO, and ACPC. The
plant is in an undeveloped area west of Vancouver, Washington. The site
is completely surrounded by chain-link fences topped with barbed wire.
Prior to the 1950s, ALCOA deposited 'spent potlinings and alumina
insulation in the same general vicinity as the current piles. (Potlining
is a carbon product that is placed in a steel rectangular pot as a lining
for the aluminum reduction process.) Spent potlining is generally
composed of carbon, sodium, aluminum, silicon, iron, and cadmium in
minimum concentrations of 1 percent. Aluminum nitride, aluminum carbide,
cyanide, sulfur, and phosphorous are present as trace elements. It was
reported that the disposal of these wastes was not veil controlled and
that wastes may have been deposited east and vest of the current piles.
Beginning in the 1950s and continuing until 1973, the wastes were taken to
Reynolds in Longviev, Washington.
The waste piles contain about 66,000 tons of waste that vere deposited on
the north bank of the Columbia River by ALCOA betveen 1973 and 1981. The
largest pile, Pile No. 1, contains only spent potlining. The pile vest of
Pile No. 1 is Pile No. 2, which contains alumina insulation. Piles No. 1
and 2 are separated by 4th Street. The third pile, Pile No. 3, contains
both types of vaste and is located east of Pile No. 1. (See Appendix for
the locations of the vaste piles.) Pile Nos. 1 and 2 vere covered by
ALCOA in 1978 and Pile No. 3 vas covered in 1981. The covers vere all
constructed using 12 mil (one one-thousandth of an inch) polyvinyl
chloride (PVC) liner placed betveen two 12-inch to 18-inch layers of
sand. ALCOA has sold portions of the plant since the wastes were
deposited, but the company retains ownership of the property where the
piles are located and much of the property surrounding the plant area.
Page 1

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B. SITE VISIT
Staff from Che Agency for Toxic Substances and Disease Registry (ATSDR)
conducted a site visit on March 15, 1989. The three waste piles were veil
vegetated. There was evidence of small breaches in the covers placed over
the piles. These breaches included holes from some type of burrowing
animal. The toes (bottoms) of the piles were not covered. Ditches
containing standing water had formed along the open bottoms of the piles.
The area surrounding the plant is relatively undeveloped. The piles are
located along the north bank of the Columbia River near the shipping
dock. This fairly remote area of Che plane sice did not appear Co be an
area where many of the workers would go, except when a ship was being
unloaded. Several railroad tracks go through the area where the piles are
loeaced. Alumina (a white fine powder) was screwn along many of the
cracks. Production wells were seen approximately 150 feet north of the
three waste piles.
A gate in the fence, south of the piles, allows access to the shipping
dock from 4th Street. The representative from VANALCO said when the
company first took over operation of the site, vagrants had been accessing
the site from the Columbia River. He said chat VANALCO appeared to have
solved this problem.
C. COMMUNITY HEALTH CONCERNS
On che basis of Che lack of complaints by cicizens Co local, Stace, or
Federal agencies about che ALCOA site, residents in the vicinity do not
seem to have site-relaCed health c?acerns. Residents should be kept
informed abouc the acCivicies occurring ac ALCOA. This will prevenc chem
from becoming concerned as a resulc of a lack of information or incorrecc
information abouc che sice.
DEMOGRAPHICS, LAND USE, AND NATURAL RESOURCE USE
The plane is located about 4 ailes west of Vancouver. The area
surrounding che plant Is relatively undeveloped. Three farms, located
ease of the plant, are operated by elderly couples on propercy leased Co
chem by ALCOA. Cattle are the primary stock on these farms. Hay crops
are grown as well. The nearest farm to the plant is located along the
northern fence line, approximately one-half mile northeast of the waste
piles.
A State game preserve is located approximately 3 miles from the plane
property co the vest. Hunting is not permitted onsite, but probably does
occur offsite. The Columbia River is used for commercial and recreational
fishing. This river also provides a habitat to numerous species of fish,
including Steelhead, American Shad, White Sturgeon, Eulachon, and five
species of salmon (Chinook, Coho, Sockeye, Chum, and Fink).
Page 2

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Private wells provide potable water to the three leased farms. The plant
ls also supplied water from the well field located north of the piles.
The water is used for all domestic purposes. Municipal wells, which
provide potable water to Vancouver residents, are located 3 miles east of
the piles.
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
A. ON-SITE CONTAMINATION
Samples were taken of the soil and groundwater. The contaminants listed
below were of public health concern.
TABLE I
On-site Contamination at ALCOA^
MEDIUM
Groundwater
|	CONTAMINANT
I
(Cyanide (total)
jCyanide (free)
|Fluoride
|Trichloroethene
CONCENTRATION RANGE
(mg/L)
0.001
<	0.005
0.015
<	0.001
406
I.1
II,517
0.020
Legend
(1) All information presented In the above table was gathered between
January 1987 and March 1987. According to the sampling technique
described, none of these samples was filtered.
B. OFF-SITE CONTAMINATION
The Columbia River vas sampled In January 1967 for cyanide and fluoride.
No cyanide vas detected, and the fluoride concentrations reported were not
of health concern. No ocher off-site,samples were taken.
C. QUALITY ASSURANCE AND QUALITY CONTROL
Conclusions contained in this Health Assessment are based on the
information received by ATSDR. The accuracy of these conclusions is
determined by the availability and reliability of the data.
D. PHYSICAL AND OTHER HAZARDS
The hazards noted ac the site were hazards Inherent in working at an
aluminum plant such as heavy machinery, molten metal, and high voltage
electricity. No other hazards were noted.
Page 3

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PATHWAYS ANALYSES
A. ENVIRONMENTAL" PATHWAYS (FATE AND TRANSPORT)
The groundwater below the waste piles is divided into four zones. The
shallow zone consists of an approximately 10-foot layer of dredged sands
The intermediate zone consists of 30 to 40 feet of silt with clay and fine
sand lenses (this layer was the original ground surface before placement of
the dredged sands). The water table is located in the intermediate zone.
The deep zone consists of a AO-foot layer of fine to medium sand. The
drinking water zone (Troutdale formation) begins 100 to 140 feet below
ground surface and consists of coarse sand and gravel.
During the wet months of the year, groundwater perches in the dredged sands
(shallow zone), collecting in areas where the original topography is low
(west of the waste piles). It then flows in a southerly direction toward
the Columbia River. The groundwater located in the intermediate zone flows
vertically through the silt unit toward the deep zone. The primary flow in
the deep zone, as well as in the drinking water zone, is to the south,
toward the Columbia River. However, both zones are influenced by the flow
in the Columbia River and, therefore, may have reverse flows periodically.
The aluminum plant's production wells are completed 100 to 140 feet below
ground surface in the coarse sand and gravel of the drinking water zone.
On the basis of a calculated maximum drawdown in the production wells of
1.5 feet, operation of the production wells is not expected to Influence
groundwater flow direction in the drinking water zone (Hart Crovser, 1987).
The production wells, which provide water for production and potable uses,
are located north of the waste piles; the closest is about 150 feet away.
Three of the wells are pumped at a time. They are pumped for several
months, and then a new group of wells is pumped. These wells supply all of
the water used at the aluminum plant. In 1985, cyanide was detected in one
of the production wells at a concentration of 0.026 mg/L, one time only.
As discussed earlier, the covers on the waste piles do not cover the toes
of the piles. There is a strong possibility that rain infiltrates the pile
toes and causes contamination to enter the groundwater in the shallow zone
where it can migrate to the Columbia River or to the other groundwater
zones. Other surface soil contamination may contribute to the groundwater
contamination as well.
The primary direction of flow in the various groundwater zones is south,
toward the Columbia River. Contamination does migrate with the groundwater
and enters the river via groundwater discharge. At this time, the dilution
factor in the River is calculated to be great enough such that there does
not appear to be a significant accumulation of contaminants. However, as
more contamination reaches the river, this situation could change.
Page 4

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Ammonia odors have been reported historically; however, none were detected
during the ATSDR site visit. If the piles are disturbed, the potential
exists that ammonia gas could be generated. Uhile the piles remain
undisturbed, this does not appear to be of concern.
Fish living in the river near groundwater recharge areas may bioaccumulate
contamination at a higher rate than those in areas where the contamination
will have a greater chance to dilute in the river. No samples were taken
of the Columbia River sediments, or of fish living in the Columbia River;
therefore, contamination may be present. Contamination of Che game animals
living in the area does not seem likely, since the waste is fairly well
contained within the piles by the covers. The site is also well fenced,
and there is nothing within the fenced area, such as grain crops, to entice
the animals over the fence.
B. HUMAN EXPOSURE PATHWAYS
The primary potential human exposure pathways appear to be ingestion of
contaminated groundwater, consumption of contaminated fish, and incidental
ingestion of or direct contact with contaminated surface water or
sediments. From the data available, the groundwater appears to flow to the
south toward the Columbia River. Cyanide was detected once in a production
well, north of the waste piles, at a concentration of 0.026 mg/L (which is
not a concentration of public health concern). The calculated cone of
influence of the wells does not appear to be large enough to affect the
flow of the groundwater significantly. As a result of the various factors
described above, human ingestion of contaminated groundwater is probably
not occurring.
Contamination is known to be reaching the Columbia River via recharge to
the river coming from the contaminated groundwater zones. Contaminants
coming from the groundwater are reportedly not at high enough
concentrations to significantly affect the water quality in the river (Hart
Crowser, 1987). The only samples taken from the Columbia River are not
adequate to confirm this. Since recreational and commercial activities are
known to occur in the river, potential contamination of the surface water,
sediment, and fish in the Columbia River with cyanide and fluoride is of
potential public health concern, if persons ingest or come into direct
contact with these media.
PUBLIC HEALTH IMPLICATIONS
The primary potential public health concern at this site is ingestion of
contaminated groundwater; however, it is unlikely that ingestion occurs.
Concentrations of some contaminants detected in groundwater monitoring
wells are of public health concern and constitute the discussion below.
Since no sampling of biota or sediment and inadequate sampling of surface
water has been done, chemical specific discussions on health implications
in these environmental media are not possible.
Page 5

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Total cyanide was detected in the groundwater at a maximum concentration of
406 mg/L. Cyanide may cause an extreme poisoning in humans, however, the
concentrations of cyanide available in the spent potlining are not high
enough to cause cyanide poisoning. Other potential effects caused by
cyanide are low blood pressure, tachycardia (rapid heart beat), headache,
drowsiness, coma, convulsions, cytotoxic anoxia (insufficient oxygen
reaching the nerve cells in the brain), and other central nervous system
(CNS) disorders caused by the effect of cyanide on both gray and white
matter in the brain.
Fluorides may cause thermal or chemical burns of the skin and irritation of
the eyes, mucous membranes, and lungs. Ingestion of fluorides may cause
nausea, vomiting, abdominal cramping, and diarrhea. Ingestion of large
concentrations may cause CNS depression or renal failure. Excessive doses
of fluoride, which is retained in the bone, may cause osteosclerosis.
Fluoride was detected at a maximum concentration of 11,517 mg/L in the
groundwater.
TCE given orally in doses of 24 or 240 mg/kg/d for a period of 14 days
produced effects including increased liver weight, decreased hematocrit,
and depressed cell-mediated immune response (Tucker et al., 1982; Sanders
et al., 1982). Based on liver tumor production in mice, Che
U.S. Environmental Protection Agency has designated TCE as a potential
human carcinogen. Long-term exposure to TCE at the maximum concentration
(0.02 mg/L) detected in the production well could result in increased risk
of cancer and other noncarcinogenie toxic effects such as liver damage and
depression of immune function. However, use of this groundwater for
potable and production uses is not of concern if the practice of mixing the
water from three wells, described in the Environmental Pathways Section, is
followed.
CONCLUSIONS
Based on the information reviewed, ATSDR has concluded that this site is of
potential public health concern because humans may be exposed to hazardous
substances at concentrations that may result in adverse health effects. As
noted in the Environmental Pathways and Human Exposure Pathways Sections
above, human exposure to surface water, sediment, and biota may be
occurring now and may have occurred in the past.
RECOMMENDATIONS
1.	A remedial action should be designed that would prevent any
infiltration of water into the piles.
2.	If the piles are removed and taken to a landfill, ambient air sampling
should be done to protect the health of on-site employees and nearby
residents (the leasing farmers) from the potential release of ammonia
gas.
Page 6

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Aluminum Company of America
Mining Waste NPL Site Summary Report
Reference 4
Telephone Communication Concerning Aluminum Company of America
From Mary Wolfe, SAIC, to Robot Keevit, EPA Region X;
August 14, 1990

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TELECOMMUNICATIONS
SUMMARY REPORT
SAIC Contact: Mary Wolfe Date: 8/14/90	Time: 1:24 p.m.
Made Call X Received Call	
Person(s) Contacted (Organization): Robert Keevit, (206) 753-9014, EPA Region X
Subject: ALCOA (Vancouver Smelter)
Summary: EPA has not completed a ROD for this site. The Remedial Investigation/Feasibility Study
was completed in July 1987 by the Potentially Responsible Party (PRP). It is still subject to final EPA
review. A (Preliminary) Health Assessment was completed by ATSDR on 5/9/90.

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Aluminum Company of America
Mining Waste NPL Site Summary Report
Reference 5
Excerpts From Feasibilty Study, Potliner Waste Piles,
Aluminum Company of America, Vancouver Smelter Operations, Washington;
Author Unknown; Undated.

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STAT! Cf WASHNCTCM
DEPARTMENT OF ECOLOGY
Ma* Slap PV-11 « Otffipk, HWtyoi «UMI) • j{)£ ()}
to, pftbciA 5-R	
LOCATIONl . S/^X^	0 ^—
fax TgLgpHOHgi go 2^1 ~^ 7# f—
ntoKi. axylfyk-l 	
	aw, ar Aw1 f Ay w ^- ^'/f:
HO, OF PACES ^ {INCLUDING THIS TRANSMITTAL SHEET)
NO, OF PAGES *J {INCLUDING THIS TRANSMITTAL SHEET)
COMMENTS! Frs^ ''	l'-fH	Poibotf—
ft/cr fllvfrl/iLisA &5. if-r /Ir.l/"! r>.;
O-ptSsiuhAnf j l/i^C/d/nj -PCcijcyk 4/t
}&(hrftj ma,
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J-1759-02
Page 23
distribution of groundwater contamination. Mo Increases
health risk are identified.
4.7.3	Institutional Issues
Groundwater monitoring la generally required by federal and
ac sites such as the ALCOA facility.
4.7.4	Cose Analysis
Costs associated with groundwater monitoring Include capital costs for
installing veils and annual costs for collecting and evaluating groundveter
samples. The capital costs are small relative to annual costs. Por the
purpose of evaluating costs» we hav
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J—1759—02
Page 36
categories: 1) continued groundwater monitoring (no action), 2) on-site
containment, and 3) remove source from site (landfill or treat).
5.1 Continued Groundwater Monitoring
o Description: This alternative Involves HBSi other than to
continue monitoring and testing groundwater samples using existing
wells.
o Advantages: Costs are significantly less than any other option. The
potential for public exposure to the pile material by excavation and
moving Is not present.
o Disadvantages: Containment or removal of source material Is not
accomplished. Additional generation of leachate and subsequent
infiltration into groundwater is likely, although under the existing
conditional there is likely no measurable impact on the Columbia River
and the potential to contaminate pullc water supplies is remote.
q I OfdoG
o Estimated Cost: «||tfBHfpreaent worth)
5.2 Contain Source On-Slce

o Discripelon: The waste piles will be covered with sn earth cover
composed of clay/sand. The sl>:e will be graded and surface water
diverted off-site via lined ditches, culverts, and below-ground
drains. The portion of the existing railroad will be moved 30 feet
south. Groundwater monitoring will continue.
o Advantages: Conventional technology and construction techniques.
Prevents infiltration Into waste piles and Teduces Infiltration around
waste piles. Durable, tfater ponding along railroad tracks and streets
will be eliminated. Equivalent to pile removal but at lower cost.

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J-1759-02
Pag* 37
Disadvantages: Will allow some infiltration outside tha waste pile
area into underlying contaminated groundwater. Source of contamination
remains in place• No treatment of contaminated groundwater.
IjliOjOOO
Estimated
c^vv idiiU	fab 9^ a9r
5.2,2 ^—	" "	" —
Discription: The waste piles will be covered with an earth cover
composed of clay/sand. The site will be graded and surface water
diverted off-site via swales in the aaphalt pavement( culverts and
below-ground drains. The site surrounding the waate piles Including
roads in the vicinity, will be paved with asphalt. The pavement would
be capable of supporting moderately heavy truck traffic. Groundwater
monitoring will continue.
o Advantages: Conventional technology and construction techniques.
Prevent infiltration below the pilea as well as the surrounding area.
Roads in area will be paved. Should reduce loading to the Columbia
River. Area can be used for storage of moderately heavy loads.
Disadvantages: Source of contamination remains in place. Higher cost
of paving with only a small gain in public environmental/health benefit.
\M°iOo6
Estimated Costi^^^^^P	i
Os/tr mrfk Srf«
C)roi"v4-ujM
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J-1759-02
Page 38
o Advantages: Loadings to the Columbia River would decline via
groundwater migration by reducing precipitation infiltration in
contaminated area due to site grading and removing contamination in
groundwater in the deep zone by pumping and treating.
Disadvantages: Costs for such a system are relatively high and source
remains on-site. Loadings to the Columbia River would increase during
pumping if treated water is discharged to the river. Residual from
water treatment would need to be disposed of in a landfill*
?>(£K5,<306
Estimated Cost:'
5.3 Remove Source from Site

5.3.:
ihjfil I dwi gyad Ufr-
Description: Waste material would be excavated and taken to Arlington,
Oregon. The site will be graded and surface water directed off-site
via lined ditched, culverts* and below ground drains. Groundwater
monitoring will continue.
o Advantages: Source material is removed from site. Risk of additional
leaehate generation is negligible. Surface water ponding Is eliminated.
o Disadvantagest Costs are significantly higher than the cover options.
Potential risk of contaminated dunt emissions during transport.
I500,000
5.3.2
o Discussion: Waste material would be excavatod and taken to Arlington,
Oregon. The site will be graded and surface water diverted off-site
via swales in asphalt pavement, culverts and below ground drains. The
entire site will be paved with asphalt, including roada in the

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J-1759-02
Pag* 39
vicinity. The pavement would be capable of supporting moderately heavy
truck traffic. Groundwater monitoring vill continue.
o Advantages: Source material is removed from site. Loading to the
Columbia River is reduced by restricting precipitation infiltration.
Less risk of water ponding on site. Roads in the area would be paved.
Disadvantages: Bigh coats. Potential risk of contaminated dust
emissions during transport.
|3, <360.0 oO
T™	u/rf/s Sik ^^eU-1
5.3.3	—
J

Description: J The waste material will be excavated and taken to
Arlington, Oregon. The site will be graded and surface vatar diverted
off-site via lined ditches, culverts, and below ground drains.
Contaminated groundwater would be pumped from wells installed to about
80 feet in depth and treated. Sludge from the treatment would be
disposed in a landfill. Treated water would be disposed into the
Columbia River. Groundwater monitoring will continue.
o Advantages: Source material removed from the site. Loadings to the
Columbia River via groundwater nigration would be further reduced by
reducing infiltration of precipitation through site grading and
removing contamination in groundvater in the deep zone through pumping
and treating.

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J-1759-02
Page 40
o Disadvantages: Very high coses over other alternative!. Potent Lai
risk of contamination dust emissions during transport. Loadings to ehe
Columbia River vould be increased during the required pumping term if
treated water is discharged to the river. Residual from water
treatment vould need to be disposed of in a landfill.
|4,100,000
Estimated Cost:
6.0 PREFERRED REMEDIAL ACTION ALTERNATIVE
Seven remedial action alternatives were developed based on evaluation of
remedial action components. Estlm&ted costs to implement the remedial
actions range from approximately 1300,000 Co $14,700,000 as summarized
below.
Description	Estimated Cost
No Action
o Continued Groundwater Monitoring	$308,000
On-Slte Containment
o Earth Cover with Site Grading
o Earth Cover with Site Grading and Paving	$1,680,000
o Earth Cover with Site Grading# Paving, and
Groundwater Pumping and Treatment	$3,610,000
Waste Removal
$1,360,000
o Waste Disposal in Landfill and Site Grading
$12,500,000

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J-l759-02
Page 41
o Waste Disposal la Landfill and
Site Grading/Paving	513,000,000
o Waste Disposal in Landfill and
Site Grading/Paving, and Groundwater Pumping
and Treating	$14,700,000
Baaed on the evaluations presented la Section 5.0, our preferred remedial
alternative consists of leaving the wastes in-place, constructing an earth
cover and grading the site so that surface vater drains away from the pile
area (5.2.1). This alternative would meat the remedial action objectives
of minimizing the generation of additional leachate which in turn will
reduce cyanide and fluoride loadings to the Columbia River.
Groundwater monitoring would also b« conducted. This monitoring would be
directed toward idantifying changes in che water quality conditions and
confirming that contamination la not migrating to drinking water wells.
Covering the waste in-place Is conn Ida red to have a similar public and
environmental health benefit as removing the waste from the site. The cost
of covering is substantially lower (on the order of $10,000,000. lower).
Paving, although not very costly, would not add substantially to reducing
leachate generation or contaminant migration to the river assuming that the
grading activities are Implemented.
Groundwater pumping and treatment would meet the remedial action objective
of reducing contaminate migration to the river, and would speed groundwater
cleanup to a degree. However, the hydraulics of the groundwater system
beneath the waste piles» and the nature of the soils and contaminants
indicate that pumping would have to occur for tens of years.
The treated water would likely be dlucharged into the Columbia River. Even
after treatment, the water that is extracted from beneath the piles would
have higher concentrations of fluoride and cyanide than groundwater
presently discharging into the Columbia River. Pumping and treating would

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J-17S9-02
Page 42
Increase the mass loading to the river while the pumping system is
operating.
Given that there appear Co be few, if any, adverse effects oa the river
under existing conditions, pumping and treating is not considered to be
cost-effective. Xbi9 remedial action component could be implemented at a
later time based on the groundwater monitoring data.
BART CROWSER, INC.
DANIEL. W. MAGEAU, P.E
Project Engineer
MATTHEW C. DALTON
Senior Associate
DWM/ JWM/MCD:taa

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Mining Waste NPL Site Summary Report
Anaconda Smelter
Mill Creek, Montana
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENT
The mention of company or product names is not to be considered an
endorsement by the U.S Government or by the U S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-O025, Work Assignment Number 20.
A previous draft of this report was reviewed by Charles Coleman of
EPA Region VIII [(406) 449-5414], the Remedial Project Manager for
the site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
ANACONDA SMELTER/MILL CREEK
MILL CREEK, MONTANA
INTRODUCTION
This Site Summary Report for Anaconda Smelter is one of a series of reports on mining sites on the
National Priorities List (NPL). The reports have been prepared to support EPA's mining program
activities. In general, these reports summarize types of environmental damages and associated mining
waste management practices at sites on (or proposed for) NPL as of February 11, 1991 (56 Federal
Register 5598). This summary report is based on information obtained from EPA files and reports
and on a review of the summary by the EPA Region VIII Remedial Project Manager for this site,
Charles Coleman.
SITE OVERVIEW
There are four separate but contiguous Superfund Sites located in the Clark Fork River Basin in
western Montana: Milltown Reservoir, Anaconda Smelter, Montana Pole, and Silver Bow
Creek/Butte Addition. All of the sites (except for Montana Pole) are contaminated by mining wastes.
The sites are located along the Clark Fork River from Butte to Missoula (see Figure 1). EPA and the
State of Montana are working together in the Superfund program to find solutions to problems created
by over 100 years of mining and processing operations and other industrial activities The Montana
Department of Health and Environmental Sciences is taking the lead on the investigations at all sites
except for Anaconda Smelter. The Atlantic Richfield Company (ARCO) is taking the lead on
investigations at the Anaconda Smelter site, with EPA oversight (Reference 3, pages 3 and 4).
Because the remediation activities at each of the four Superfund Sites could affect the activities at all
the others, a master plan was created to coordinate investigation and clean-up for all Clark Fork Basin
sites. In addition to these technical interrelationships, geographical and legal relationships between
the sites also exist. Because all four sites are sources of contamination to Silver Bow Creek and/or
the Clark Fork River, response actions need to be coordinated so that downstream, or downgradient,
sites are not recontaminated during clean-up at upstream, or upgradient sites. The similar types of
mining wastes, with similar metallic contaminants, affect human health and the environment through
the same environmental pathways. Thus, many response actions at the four sites will be closely
related (Reference 3, page 4).
1

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Anaconda Smelter
LOCATION OF
8UPERFUNO
SITES
IDAbO
CLARK FORK RIVER
DRAMAQE BA?M ¦
Approximation of
Clark Fork Rlvar
Orainaga BaaW>
FIGURE 1. LOCATION OF SUPERFUND SITES IN THE CLARK FORK RIVER
BASIN
2

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Mining Waste NPL Site Summary Report
The Clark Fork Basin sites were divided into 77 different contamination problems, and these 77 were
then consolidated into 25 Operable Units. Operable Units were identified as high, medium, or low
priority (see Table 1) (Reference 3, pages 4 and 5).
TABLE 1. PROPOSED LIST OF PRIORITIES OF CLARK FORK OPERABLE UNITS
High-priority Operable Units
Mill Creek
Walkerville
Butte Priority Soils
Old Works Removal
Flue Dust
Warm Springs Ponds
Travona Flooding
Montana Pole
Mine Flooding (Berkeley Pit)
Rocker
Medium-priority Operable Units
SBC Area I (Metro Storm Drain - Colorado Tailings)
Streameide Tailings (Colorado Tailings - Warm Springs Ponds)
Smelter Hill
Clark Fork River
Milltown Reservoir
Anaconda Community Soils
Anaconda Site-wide Ground Water
Old Works (General)
Low-priority Operable Units	
Butte Non-Priority Soils
Tailings (ground water/alluvium)
Arbiter
Smelter Wastes (beryllium, slag)
Anaconda Surface Water and Sediment
Agricultural Lands
Active Mine Area
Work on Operable Units shown in boldface has begun; this includes all high-priority and most
medium-priority Operable Units
3

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Anaconda Smelter
This summary will be focusing on the Anaconda Smelter site and its 12 Operable Units (see Figure
2). This site was proposed for the NPL in December 1982, and finalized in September 1983 The
Operable Units are:
•	Mill Creek
•	Smelter Hill
•	Flue Dust
•	Old Works
•	Arbiter
•	Beryllium Disposal Areas
•	Community Soils
•	Slag Piles
•	Tailings/Alluvium
•	Regional Soils
•	Regional Ground Water
•	Surface Water and Sediment (Reference 4, page 3).
Of these 12, there is only 1 Operable Unit for which a remedial action has been chosen and
implemented: the Mill Creek Community Operable Unit. Mill Creek was the first priority at this
site, and it is the only Operable Unit for which a Remedial Investigation and Record of Decision
(ROD) have been completed. In addition, a detailed Endangerment Assessment was prepared for
another Operable Unit: the Flue Dust Operable Unit. Therefore, this summary will concentrate on
the two units mentioned above, but will provide available information on the other units as well.
Mill Creek Operable Unit
Because of the health hazards found there, the Mill Creek area is the first Operable Unit that received
attention at the Anaconda site. Mill Creek is an unincorporated community located approximately 25
4

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Mining Waste NPL Site Summary Report
Anaconda Superfund Site Operable Unit Locations
Aetiritiea Legend
CTO	I niln UUm H*m»
Utim f|W«
rrm"
ict n/ci iMnr
ET3 B/Cl CapW*
n B/n
E3 B/n 			
E3
(WH ItfMkUtw
E3 ba«pQrtunity Ponds*
*-	o z o>
Warm
Springs Ponds
Mill-Willow
Bypass
2VZVZ
naeonial
nis*£
~«v"
inaconda
3pp< rtui litjrf
/
Flue Dust
Sites
Hill Creek
Smelter Hill
CUrk Fork CIS Protect
Scale of Kites
CP»90-6j
FIGURE 2. ANACONDA SUPERFUND SITE OPERABLE UNIT LOCATIONS
5

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Anaconda Smelter
miles west-northwest of Butte, Montana. It covers 160 acres of land and lies adjacent to the smelter
(Reference 1, page 7).
The contaminants of concern in this Operable Unit are arsenic, lead, and cadmium. Arsenic dust in
the air, and arsenic, cadmium, and lead in the soil and drinking water present public health risks
The community of Mill Creek originally (prior to July 1986) consisted of 37 households and less than
100 people (Reference 1, page 34). Significant health risks were identified for children and adults in
Mill Creek. Household water supplies (drawn from wells) were tested and found to contain arsenic;
in addition, arsenic was found at elevated levels in children's urine (Reference 1, page 14).
Because of the threat to human health, the Mill Creek area was the first Operable Unit to be
designated at the Anaconda Smelter site. EPA drafted a ROD in October 1987, which required the
permanent relocation of all residents and temporary stabilization of the Mill Creek area. This
decision was an interim remedy designed to protect the health of the residents of Mill Creek
(Reference 1, page 2). The State of Montana concurred with the selection of this interim remedy.
The cost was estimated at $1.7 million total present worth; however, only $300,000 was required to
complete the remedy since Anaconda Minerals Company had acquired all but eight residences prior to
the implementation of the ROD (Reference 1, page 51). The RODs for subsequent Operable Units
will address a permanent remedy for the Mill Creek area (Reference 1, page 3)
Flue Dust Operable Unit
The Flue Dust Operable Unit involves investigation of flue-dust piles at several locations at the
Anaconda smelter site. Flue dust is a fine-grained waste material which was formed in the smelter
flue. The dust contains high concentrations of arsenic, cadmium, copper, lead, and other metals
The amount of flue dust stored onsite, as of December 1989, was estimated to exceed 316,000 tons
(Reference 6, page ES-1). The Remedial Investigation for the Flue Dust Operable Unit is currently
underway, and a Final Remedial Investigation/Feasibility Study is expected in the spring of 1991
(Reference 4, pages 2 and 3).
OPERATING HISTORY
The Anaconda Copper Mining Company first began copper smelting operations in 1884 at the "Upper
Works" smelter, located 26 miles west of Butte. The Upper Works consisted of a concentrator and
smelter buildings, which housed roasters and reverberatory furnaces, all connected to masonry flues
and two smokestacks measuring 115 and 175 feet tall. By 1887, the company had expanded and built
an additional smelter 1 mile east of the Upper Works (along Warm Springs Creek). The new smelter
6

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Mining Waste NPL Site Summary Report
was known as the "Lower Works" (Reference 7, page 2). By 1889, an electrolytic copper refinery
had been built as well, and was located between the two smelters Due to a shortage of smelting
capacity, a larger, more efficient copper smelter was planned and built to the south of the Upper and
Lower Works. The new smelter was completed in 1902, and is known as "Smelter Hill" or the
"Washoe Smelter." The Upper and Lower Works were subsequently demolished in 1903 The
Washoe Smelter or Washoe Works operated from 1902 to 1980. Copper smelting had been occurring
at what is currently the Anaconda Superfund Site for almost 100 years (from 1884 to 1980)
(Reference 7, pages 2 and 3).
Copper ore processing has produced wastes that cover over 6,000 acres and contain elevated levels of
arsenic, cadmium, copper, lead, and zinc. Wastes include 185 million cubic yards of tailings (pond);
27 million cubic yards of granulated slag (pile), and 0 25 million cubic yards of flue dust. The
historic stack emissions resulted in the contaminated soils near the smelter. Ongoing fugitive flue-
dust emissions (from piles) and fugitive dust emissions from the soil have contaminated the
community for over 100 years (Reference 1, pages 9 and 12)
The smelter was originally operated by Anaconda Copper Mining Company (Anaconda Company),
until it merged with ARCO in 1977. From 1977 to 1980, ARCO operated the smelter; today, it owns
the site of the former smelter and the surrounding areas near Mill Creek through its Anaconda
Minerals Company Operating Unit (Reference 1, page 9). All of the structures at the Anaconda
Smelter site, except for the stack, were demolished after 1980, when the facility ceased to operate
(Reference 6, page ES-1).
SITE CHARACTERIZATION
A description of each Operable Unit and the current activities at each unit follows:
•	Mill Creek - Mill Creek is a residential community located adjacent to the Anaconda Smelter,
which was contaminated by airborne dust containing metals (primarily arsenic). Residents
were relocated in 1986 due to the health hazard from exposure to metals. Current activity
includes maintaining vegetative cover (Reference 4, pages 2 and 3)
•	Smelter Hill - Smelter Hill is also referred to as "Washoe Smelter" and includes the former ore
processing area owned by ARCO and additional property upgradient from Mill Creek,
including the Smelter Hill railroad loop. This Operable Unit has soil and ground-water
contamination by metals (Reference 4, pages 2 and 3).
7

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Anaconda Smelter
•	Flue Dust - Flue dust resulting from smelter operations contains high concentrations of arsenic,
cadmium, and lead. Piles are stored in and around the Smelter Hill complex Currently, EPA
and ARCO are researching methods to reduce the mobility of the dust (Reference 4, pages 2
and 3).
•	Old Works - This area is the site of the first smelters in Anaconda (also referred to as the
Upper and Lower Works). Wastes (tailings) are located in a 100-year floodplain along a 2 75-
mile stretch of Warm Springs Creek and around the Upper and Lower Works. These areas are
the focus of a removal operation. In addition, waste piles and soils at the smelter site and
surface water near the site will be sampled. Clean-up is scheduled for the 1991 field season
(Reference 4, pages 2 and 3).
•	Arbiter - The Arbiter plant was a copper refining plant that produced cathode copper from
sulfide ores using an ammonia leach process. Slurry wastes from this inactive plant contain
arsenic, cadmium, lead, and zinc, and are located in a pond near the plant Clean-up is
scheduled for the 1991 field season (Reference 4, pages 3 and 5).
•	Beryllium Disposal Areas - A beryllium flake-metal pilot plant and a beryllium oxide pilot
plant were operated on Smelter Hill between 1964 and 1968. Following closure, waste
containing beryllium was disposed of in the Opportunity tailings pond Other wastes from the
plants were placed in a nearby bunker (Reference 4, pages 3 and S).
•	Community Soils - This Operable Unit includes nearby community soils contaminated by
smelter emissions which require clean-up. The communities targeted for clean-up are
Anaconda, Opportunity, Warm Springs, Galen, and Deer Lodge. Three areas in the Town of
Anaconda are currently undergoing soil-sampling activities (Reference 4, pages 3 and 5).
•	Slag - Slag piles are located next to the Anaconda tailings pond and industrial buildings on
Smelter Hill and at the Old Works. Slag is the material separated from the metal during the
refining process; it consists of 85 percent silica dioxide (sand) and approximately 15 percent
iron oxide (Reference 7, page 8).
•	Tailings/Alluvium - Tailings make up the largest volume of yvaste at the Anaconda Smelter
site. Tailings were deposited in the Anaconda and Opportunity ponds The Opportunity ponds
stretch approximately 3 miles across from east to west. The volume of tailings from both pond
areas is 185 million cubic yards (Reference 4, page 3; Reference 1, page 9 and Figure 2)
•	Regional Soils - This Operable Unit includes contaminated agricultural lands surrounding the
Anaconda Smelter which require clean-up (Reference 4, pages 3 and 5)
•	Regional Ground Water - This Operable Unit includes regional ground water which is
contaminated by the Anaconda Smelter. A ground-water screening study is being conducted to
discern potential ground-water contamination from sources such as the Opportunity ponds, slag
piles, red sands, tailings, Old Works area, and regional contaminated soils (Reference 4, pages
3 and 5).
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Mining Waste NPL Site Summary Report
• Surface Water and Sediment - Tailings have migrated into streams near the site, such as Warm
Springs, Mill Creek, and Willow Creek (Reference 4, page 3)
The Anaconda Smelter was listed on the NPL in September 1983 (Reference 6, page 70). The
contamination of the Mill Creek community was discovered during the Phase I Remedial Investigation
of the site. Sources of contamination included the flue-dust piles and the slag piles, both located at
the Washoe Smelter and the tailings pond located at the Opportunity plant (Reference 1, pages 13 and
14). Among these three sources, the flue dust contained the highest concentrations of arsenic,
cadmium, copper, and lead. Concentrations of arsenic in the flue dust ranged from 59,900 to 69,600
parts per million (ppm). These concentrations were up to three orders of magnitude greater than
concentrations reported in other wastes (Reference 5, page 25) Exposure pathways were the
inadvertent ingestion of contaminated soil by children and adults of Mill Creek, ingestion of
contaminated drinking water; and inhalation and ingestion of airborne dirt and household dust by
adults and children (Reference 6, pages 5-7 and 5-8) Contaminants of concern for the Mill Creek
community were arsenic, lead, and cadmium (Reference 1, page 14).
Soils
It was discovered that the soil contamination (by arsenic, cadmium, and lead) in Mill Creek was
widespread. The geometric mean concentration of arsenic in Mill Creek surface soils is 638
milligrams per kilogram (mg/kg); for cadmium it is 25 mg/kg; and for lead it is 508 mg/kg. These
mean values are much higher than values for surrounding communities (Reference 1, page 18).
Spatial and vertical distribution of contaminants was studied in 1982, and from 1984 to 1986 The
results of the study showed that arsenic is concentrated in the top 6 inches of the soil. At a depth of
18 inches, concentrations are below 100 mg/kg. Arsenic concentrations approach background levels
at 42 inches below the surface (Reference 1, pages 19 and 25). The highest concentrations of
cadmium and lead are also found in the first 6 inches of the soil profile. However, lead and cadmium
concentrations decrease more rapidly with depth than the arsenic concentrations Cadmium levels
were found to be less than detection limits (1.2 to 1 5 mg/kg) at a depth of 9 inches, and lead levels
reached background levels below 6 inches (Reference 1, page 25)
Ground Water
The water table underlying Mill Creek is 20 feet or deeper below the surface, and is located in
Quaternary alluvial deposits. Domestic well water is drawn from this aquifer. Domestic tap water
9

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Anaconda Smelter
was tested in 1985, 1986, and 1987, and results showed that all the households tested were within
EPA primary drinking water criteria and within Montana's primary drinking water standards for
arsenic, cadmium, and lead. However, in the 1986 sampling, seven household water supplies were
found to have detectable arsenic levels. Cadmium and lead levels were mostly at (or below) detection
limits. The wells contaminated with arsenic may have been affected by soils introduced into the wells
(Reference 1, page 25).
Surface Water
Mill Creek is the major drainage system in the area of the Anaconda Smelter and the Mill Creek
community. Mill Creek was sampled four times between April 1985 and April 1986 (Reference 1,
page 25). Results showed that arsenic was present in the creek above detection limits [4 micrograms
per liter (jig/\)] for several of the tests. Total arsenic concentrations ranged from 12 to 32 2 /xg/1
Zinc was also detected in the waters of Mill Creek Sediments of the creek were also tested twice
during 1985; results showed that trace-metal concentrations in the sediments were consistently lower
than levels in surrounding soils (Reference 1, page 27).
Air
Releases of dust and emissions containing arsenic, cadmium, and lead occurred during the almost 100
years of operation of the smelter, and fugitive-dust emissions continue today (from the flue-dust piles
and other wastes at Smelter Hill). Until transport of contaminated soil into Mill Creek is controlled
or remedied, it is estimated that recontamination of Mill Creek wilt occur at a rate of 1 5 micrograms
per kilogram (/tg/kg) of soil per year (Reference 1, page 27).
In 1984, samples of airborne particulate matter were collected at four different locations near the
smelter and tested for total suspended particulates, respirable particulates, and trace-metal content
(Reference 1, page 27). Arsenic (air) concentrations at one monitoring station east of the smelter
were found to be 10 times greater than background levels [0.01 micrograms per cubic meter (jig/m3)].
Arsenic concentrations were 0.1 jig/m3. The highest arsenic concentration found at the Mill Creek
station was 0.681 figlm3 Elevated levels of cadmium, lead, and arsenic were found in household
dust samples as well. Residential dust showed an average of 264 mg/kg arsenic, and indoor
respirable arsenic concentrations were (on average) 0.019 uglm5 (Reference 1, page 31)
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Mining Waste NPL Site Summary Report
ENVIRONMENTAL DAMAGES AND RISKS
Environmental damages and risks have been studied and quantified for 2 of the 12 Operable Units at
the site: the Mill Creek Operable Unit and the Flue Dust Operable Unit. Risks associated with these
two Operable Units are described below.
Mill Creek Operable Unit
The multimedia contamination of the Mill Creek community was discovered during the Phase I
Remedial Investigation. The soil sampling of the Mill Creek community showed much higher levels
of arsenic and other heavy metal contaminants than other communities in the area. In March 1985,
the Center for Disease Control (CDC) conducted urine sampling of pre-school children in Mill Creek,
and found that these children had a greater arsenic exposure than children from another community in
the Anaconda area. Even after CDC attempted to reduce children's exposure to household dust (by
recommending certain house-cleaning methods, etc.), the urinary arsenic levels of these children
remained high (Reference 1, page 12).
A detailed Endangerment Assessment was conducted in 1986 This assessed the actual and potential
exposures of residents to hazardous substances through soil, air, drinking water, and household dust
After the results of the Endangerment Assessment and the CDC study were reviewed, EPA requested
funding to temporarily relocate high-risk residents of Mill Creek (Reference 1, page 12).
Under an Administrative Order on Consent, in July 1986, Anaconda Minerals Company agreed to
conduct an expedited Remedial Investigation/Feasibility Study focusing on human health issues
While the Remedial Investigation/Feasibility Study was ongoing, ARCO reached agreements with
most of the Mill Creek residents to permanently relocate them. Due to the relocation efforts, of the
original 36 households, only 8 were inhabited as of October 1987. Mean urinary arsenic levels of
residents of Mill Creek decreased after residents were relocated (Reference 1, page 13).
Arsenic is a known carcinogen, associated with an increase in the frequency of skin cancer when
ingested, and lung cancer when inhaled (Reference 1, page 14). Arsenic can also be acutely toxic
Cadmium has been associated with an increase in frequency of lung cancer when inhaled, and can
also be acutely toxic. Lead is a cumulative poison and can cause neurological, kidney, and blood-cell
damage in humans. Copper and zinc can be toxic to many animal species and humans when at
elevated levels. Since no National standards existed regarding the carcinogenic risk from exposure to
arsenic in soil, the EPA calculated the risk in accordance with the guidelines for carcinogenic risk
assessment (Reference 1, page IS). After calculating cumulative exposure for each contaminant, the
cumulative risk estimates for each substance were used to assess potential risks associated with
11

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Anaconda Smelter
multiple chemical exposures. Carcinogenic risks for multiple chemical exposure were found by
adding cadmium and arsenic lung cancer risks. Noncarcinogenic risks from multiple chemical
exposure were estimated by deriving a cumulative hazard index for ingested cadmium and inhaled or
ingested lead (Reference 1, pages 15 and 16).
If no action was taken, (under the average exposure scenario) the excess risk from all exposure
pathways of developing skin cancer in Mill Creek is 1.5 x 104; under the maximum exposure
scenario, the excess skin cancer risk is 2.8 x 10'3. Regarding lung cancer from all exposure
pathways, the excess cancer risk for the average exposure is 1.0 x lO"1; for the maximum exposure it
is 1.6 x 10"3. The cumulative hazard index for cadmium ingestion and lead exposure was found to be
0.73 in the average case and 1.96 in the maximum case. An index greater than 1 indicates that
exposure to a particular substance exceeds a "level of concern" (Reference 1, page 16).
EPA considered the cumulative carcinogenic risk and toxic risk from contaminants in Mill Creek to
be of enough significance to warrant action such as relocation. The contamination of Mill Creek
posed an "imminent and substantial endangerment to the health of any children who may reside there"
(Reference 1, page 18).
Flue Dust Operable Unit
Flue dust may contaminate the environment through a number of pathways, including wind erosion of
the flue dust, followed by dispersion of these particles in the air, and then accumulation in the soil, or
leaching of the contaminants by rain or melting snow. Leachates formed could contaminate surface
waters and/or ground water. Populations of potentially exposed persons include current offsite
residents of East Anaconda, individuals who may visit onsite flue-dust piles (dirt-bike riders), or
hypothetical future onsite residents. Exposure of individuals may be through inhaling suspended
particles or incidental ingestion of soil contaminated by flue dust (Reference 6, page ES-1).
Exposure of individuals to contaminants from flue dust cannot be directly measured due to the many
different sources at the site contributing the same contaminants. Therefore, risk analyses were based
on total concentrations of airborne metals, and not solely on metals from flue dust. Through risk
analyses, it was deduced that an imminent and substantial endangerment exists for any future onsite
residents. A high risk of lung cancer exists (from 1 in 100 to 7 in 100) from inhalation of arsenic in
air. A lower, but still significant, risk of lung cancer from cadmium in air (from 1 in 10,000 to 4 in
10,000) exists In addition, a high risk of skin cancer due to ingestion of arsenic is also present
(from 4 in 100 to 3 in 10) (Reference 6, page ES-2).
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Mining Waste NPL Site Summary Report
Occasional visitors to the site, such as dirt-bikers, are likely to encounter risks of lung cancer (3 in
100,000) or skin cancer (S in 100,000). These risks levels could increase if individuals make
frequent and extended visits to the site (Reference 6, page ES-2).
The lifetime lung cancer risks to current residents of East Anaconda appear to be 2 in 100,000 from
exposure to arsenic in the air. Skin cancer risks for these residents due to ingestion of arsenic in soil
are ftom 1 in 10,000 to 4 in 10,000 (Reference 6, page ES-2).
REMEDIAL ACTIONS AND COSTS
Investigation is ongoing for most Operable Units at the site, with remediation to be initiated as these
investigations are completed. However, remedial actions have been conducted at the Mill Creek
Operable Unit.
The final actions chosen for the Mill Creek Operable Unit were permanent relocation of residents and
temporary stabilization of the site. EPA did not address all public health and environmental issues in
Mill Creek in the ROD. The remaining issues will be considered under separate Operable Unit
investigations (Reference 1, pages 3, 48, and 49).
The permanent relocation of residents reduces the excess skin cancer risk to 4.7 x 10"5 (average case)
and 1.7 x 10~* (reasonable maximum case) for all residents. Permanent relocation of residents had the
lowest cost of all the alternatives developed. Because ARCO had relocated all but eight residences,
the net cost was $300,000 for completion of the remedy (Reference 1, pages 39 and 42).
This remedy involves buyout of all remaining property owners in Mill Creek and may require
condemnation of the community by the United States or the State of Montana. Condemnation would
be required if certain residents were recalcitrant and did not wish to relocate EPA plans demolition
of all structures, and fencing and posting of the entire area (Reference 1, page 49). Demolition
debris will be hauled to the smelter where it will be consolidated with demolition debris from the
smelter complex (Reference 2, page vii). Subsequent to demolition, temporary stabilization will be
performed. This will entail stabilizing disturbed areas to prevent erosion damage by establishing and
maintaining vegetation (Reference 1, page 49). Operation and maintenance will entail monthly
inspection of fencing, vegetative cover, and the debris disposal area (Reference 2, page xvi).
Because continued transport (by air) of contaminants into Mill Creek is possible, the final remedy for
the Mill Creek area will be addressed at the same time as the remedy for the Anaconda Smelter
(Reference 1, page 49).
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Anaconda Smelter
The alternative chosen in the ROD was in EPA's judgement the most protective of all available
alternatives, having the lowest risk (using health risk assumptions from the Endangerment
Assessment) Relocation also has the lowest cost, at $1.7 million total present worth (1987)
However, only $300,000 is necessary to complete relocation. There are minimal environmental
impacts associated with this alternative and it will be consistent with any final remedial action
(Reference 1, page 51).
CURRENT STATUS
According to the EPA Remedial Project Manager, as of May 9, 1991, the Anaconda Smelter
Superfund Site is undergoing site management. In the next few months, some of the Operable Units
will be consolidated (there are currently 12). EPA is considering combining the Regional Ground
Water, Surface Water and Sediment, Tailings and Alluvium, and Slag Operable Units into a single
Operable Unit.
The current status of each Operable Unit is described below-
•	Mill Creek - All residents have been relocated. Current activity includes maintaining
vegetative cover.
•	Smelter Hill - The Remedial Investigation/Feasibility Study is underway with a remedial-
alternatives screening document expected to be released in 1991 A ROD is expected to be
completed in 1993.
•	Flue Dust - A ROD is expected in the fall of 1991.
•	Old Works - Expedited response actions are scheduled to begin during the later part of the
1991 field season.
•	Arbiter - Expedited response actions are scheduled to begin during the later part of the 1991
field season.
•	Beryllium Disposal Areas - Expedited response actions are scheduled to begin during the later
part of the 1991 field season.
•	Community Soils - A Decision Document is expected in the summer of 1991 with remediation
scheduled for 1991 to 1992. Currently, an expedited response action (removal) is underway
•	Slag - This is a low priority Operable Unit and may be combined with the Regional Ground
Water Operable Unit and other Operable Units into a single unit as described above.
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Mining Waste NPL Site Summary Report
•	Tailings/Alluvium - As discussed above, EPA is considering combining this Operable Unit
with others to be addressed as a single Operable Unit.
•	Regional Soils - Additional sampling is planned.
•	Regional Ground Water - EPA is currently developing a work plan for data collection. As
discussed above, EPA is considering combining this Operable Unit with others to be addressed
as a single Operable Unit.
•	Surface Water and Sediment - As discussed above, EPA is considering combining this
Operable Unit with others to be addressed as a single Operable Unit (Reference 4, pages 2, 3,
and 5; Reference 1, page 9).
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Anaconda Smelter
REFERENCES
1.	Superfiind Record of Decision: Anaconda Smelter/Mill Creek, Montana; EPA; January 6, 1988.
2.	Remedial Action Plan, Mill Creek, Montana, Undated.
3 Clark Fork Superfiind Master Plan; EPA and Montana Department of Health and Environmental
Sciences; October 1988
4.	Anaconda Smelter Site: Superfiind Progress Report; EPA Region VIII; June 1990.
5.	Mill Creek Remedial Investigation/Feasibility Study, Final Remedial Investigation Report, Mill
Creek, Montana, Anaconda Smelter Superfund Site, First Operable Unit; Prepared for EPA by
Anaconda Minerals Corporation; September 1987.
6.	Endangerment Assessment for the Anaconda Smelter Site, Final Draft for the Flue Dust Operable
Unit; Life Systems, Inc.; December 20, 1989.
7.	Site History of Smelter Hill - Anaconda Smelter NPL Site; Prepared for ARCO Coal Company
by GCM Services, Inc.; June 1989.
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Mining Waste NPL Site Summary Report
BIBLIOGRAPHY
EPA. Superfund Record of Decision: Anaconda Smelter/Mill Creek, Montana. October 1987.
EPA and Montana Department of Health and Environmental Sciences Clark Fork Superfund Master
Plan. October 1988.
EPA and Montana Department of Health and Environmental Sciences. Progress Report - Clark Fork
Basin Superfund Sites. May 1990.
EPA Region VIII. Record of Decision: Anaconda Smelter Superfund Site, First Operable Unit
October 1987.
EPA Region VIII. Anaconda Smelter Site- Superfund Progress Report June 1990.
Life Systems, Inc. Endangerment Assessment for the Anaconda Smelter Site, Final Draft for the Flue
Dust Operable Unit December 20, 1989.
National Priorities List, Supplementary Lists and Supporting Materials. February 1990.
Prepared for ARCO Coal Company by GCM Services, Inc. Site History of Smelter Hill - Anaconda
Smelter NPL Site. June 1989.
Prepared for ARCO Coal Company by PTI Environmental Services. Anaconda Smelter Remedial
Investigation/Feasibility Study, Smelter Hill Operational History, Part I, Reduction Works
June 1989.
Prepared for EPA by Anaconda Minerals Corporation. Mill Creek Remedial Investigation/Feasibility
Study, Final Remedial Investigation Report, Mill Creek, Montana, Anaconda Smelter Superfund
Site, First Operable Unit. September 1987.
PTI Environmental Services. Anaconda Smelter Remedial Investigation/Feasibility Study, Smelter
Hill Operational History Part II, Operational Smelting Practices. Undated.
PTI Environmental Services. Anaconda Smelter Remedial Investigation/Feasibility Study, Smelter
Hill Operational History Part III, Concentrator Operations. June 1989.
PTI Environmental Services. Anaconda Smelter Remedial Investigation/Feasibility Study, Summary
Report, Anaconda Smelter NPL Site, General Work Plan Deliverables June 1989
Remedial Action Plan. Mill Creek, Montana. Undated.
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Anaconda Smelter
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From Superfund Record of Decision:
Anaconda Smelter/Mill Creek, Montana;
EPA; January 6, 1988

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Enwenmemo Prowcw
A«*iKf
Emwgmer «na
nanwM Amoorm
Oesoar iM7
X* EPA Superfund
Record of Decision:
Anaconda Smelter/Mill Creek, MT

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1986 (SARA), and the National Contingency Plan. The State of Hontana and
the Federal Emergency Kanagement Aganey (FEHA) hav« concurred on the
selected remedy of permanent relocation of Hill Craak residents v;cM
temporary sita stabilization.
STATEMENT Of BASIS
This decision is based upon the administrate record which has baan
compiled for the Hill Craak Oparabla Unit, including tha following
docuaents:
o Final Remedial Investigation Report, Hill Craak Oparabla Unit,
Anaconda Smelter Sita. September 1987. Prepared by tha Atlantic
Richfiald Company for U.S. EPA, Region 8.
o Final Feasibility Study Raport, Mill Craak Oparabla Unit. Anaconda
SMltar Sita, September 198?. Prepared by tha Atlantic Richfiald
Coapany for U.S. EPA, Region 8.
o Final Revised Endangerment Assessaent: Mill Craak, Montana
(Anaconda Saaltar Sita) Saptaabar 1987. Prepared by Claaant
Aaaoclatas, Inc. for U.S. EPA. Ragion 8.
o Suaaary of Remedial Altarnativas Selection (attached harato).
o Responsiveness Suaaary (attached harato).
o Other reports, documents, correspondence, etc. included in tha
Adainistrativa Racord (sea attached index).
DESCRIPTION OF SELECTED REMEPT
Tha raaady for Mill Craak, Montana selected by EPA is tha interla first
oparabla unit raaady of permanent relocation of all Mill Craak residents.
Pollovlnf relocation of all residents, tha area will be temporarily
stabilized. Tha contaainatad soils in Mill Craak vlll be addressed as part
of tha raaady for tha Anaconda Saaltar NPl site. Tha contaainatad debris
froa tha relocation or daaolition activities vill ba consolidated and
teaporarily stored vith similar debris on Smelter Rill. Final disposition
of these materials vill be addressed as part of the final remedy for tha
Anaconda Saalter NPl site. Areas disturbed by tha relocation/demolition
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activities vill be regraded and revegetated. Operation and maintenance
requirements for the selected alternative will include monitoring and
maintenance of the vegetative cover used to stabilize disturbed areas and
installation and maintenance of a fence around the perimeter of the site.
Short term Institutional controls to control access and land use vill also
be implemented.
The selected Interim remedy provides adequate protection of the health of
current residents of Mill Creek. This alternative is the most cost
effective alternative considered and would result in the lowest estimate of
excess risk to public health. This renedy is also environmentally
preferable to all other remedies and is necessary because of the potential
for recontamination of the Hill Creek area from vind blown dust from
surrounding areas contaminated with arsenic, cadmium, and lead. A
"cleanup" remedy at this time would therefore not be reliable over the long
term. The selected remedy complies with all applicable or relevant and
appropriate Federal and State requirements addressing the Interim remedy of
parmanent relocation and temporary site stabilization. CERCLA
sub-paragraph 121(d)(4)(a) allows the selection of a remedy that does noc
attain a level or standard of control at least equivalent to all legally
applicable or relevant and appropriate Federal and State standards,
requirements, criteria, or limitations if the remedial action selected is
only part of a total remedial action that vill attain such level or
standard of control when completed. The Record of Decisions for subsequent
operable unit(s) addressing Hill Creek vill select applicable or relevant
and appropriate requirements associated with permanent remedies. The
evaluation aad identification of such requirements in Remedial
Investigation/Feasibility Studies do not represent final EPA
doterslnatloru.
In accordance vith Section 121(b) of CERCLA, alternative permanent
solutions and alternative treatment technologies vere evaluated (deep
tilling, soil leaching, etc.). Review indicated that these treatment
technologies did not adequately reduce surface contaminant levels belo-.
1

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public health concerns. However, further testing is needed to evaluate
other technologies. Innovative technologies end permanent remedies will b<
fully evaluated in RX/FS work for the final remedy at the Anaconda Smelter
NFL site.
The Anaconda Smelter Superfund site consists of the Anaconda Old Works and
Anaeonda (Vashoe) Saelter sites, the Arbiter Plant, nuaerous waste piles
and vaste ponds, various deaolition duaps, and associated areas
concaalnated by aerial deposition of saelter stack aalsslons. The total
Superfund site area covers several tens of square alles. Several operable
units have been designated (AO CFK Sub-section 300.68(c)) based on
slallarlties In the nature of the contaainatlon, the location of the
concaalnated aedia and the ability of areas to b« reaediated under similar
tlae fraaes. The Hill Creek Operable Unit is the first operable unit at
the Anaeonda Saelter site vhlch has received focused attention ovtr the
past year owing to the highest docuaented level of envlronaental
contaainatlon of all comnunities in the area, the deaonstrated exposure of
Mill Creek children to smelter contaminants, and the associated risks to
human, health.
As previously stated, the purpose of the Hill Creek interia remedy is to
provide adequate peraanent protection for the health of current residents
in Hill Creek, Montana and Interia protection of the health of future
short-tera visitors In the area. Soae envlronaental concerns vill be
addressed vlthin the llaits of the selected reaedy. For exaaple, fugitive
dust vill be ainiaized during house deaolition and site revegetation
efforts. Bovaver, regional contaainatlon probleas vhich aay reaain in Hill
Creak after iapleaentation of the interia reaedy vill be addressed under
separate operable units. The final reaedy for soils and ground vater will
be deterainad following the RI/FS reports for these remaining operable
units.
As required by Section 121(d)(2) of CERCIA and *0 CFH Section 30°.68. the
final reaedy vill attain or exceed applicable or relevant and appropriate
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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
This part of the Record of Decision (ROD), summarizes the information E?A
used and the evaluations conducted to support the selection of the interix
remedy for Mill CreeW, Montana. In addition to the sunaary text,
Attachments I. II. Ill, and IV provide EPA's: Responsiveness Summary.
Statement of Findings for Floodplains and Vetlands. Confidential
Enforcement Analysis, and Administrative Record Index, respectively. This
Information collectively is EPA's record of decision supporting the
selection of permanent relocation vith temporary site stabilization as the
Interim remedy for Mill Creek, Montana.
I. SITE LOCATION AND DESCRIPTION
The unincorporated community of Mill Creek is located in southwestern
Montana at the southern end of Deer Lodge Valley approximately 25 miles
west-northvest of Butte, Montana and about 1.5' miles east of Anaconda.
Montana (Figure 1). The study area is located immediately adjacent to the
Anaconda Smelter.
Mill Creek (also known as Silica), Montana is located immediately adjacent
to the Anaconda Smelter site. The community covers an area of 160 acres,
70 of vhich are owned by the Anaconda Minerals Company (AMC). Most of the
surrounding lands are owned by AMC (Figure 2).
The principal ground water bearing structure in the immediate vieinity of
the site is a shallow alluvial aquifer consisting of characteristically
eoarse grained fan and floodplain deposits that are moderatly permeable ard
hydraulically connected with surface streams. The study area is in the
Hill Creek drainage, a tributary of Silver Bow Creek, which flows directi;,
through the Varm Springs tailing pond complex.
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II. SITS HISTORY AND CURRENT SITE STATUS
A. SIc« History
Residents moved into the Hill Creek aria due to its close proximity to the
Anaconda Saelter sit*. The first filing on record for land in the Mill
Creek araa vu in 1902. By 1916-1917, a largt part of the Hill Creek area
contained tants, log houses, and shaeks. By 1918, a sehoolhouse vas moved
to tht Mill Creek community. Eventually, the community vas divided into
the Millviev lots* as shovn in Figure 2.
The Anaconda Saelter vas operated for nearly a century beginning in 188^
and ceasing in 1980. Tho saelter vas initially operated by the Anaconda
Copper Coapany (later renamed the Anaconda Coapany), and its predecessors
in interest. The Anaconda Company morged vith tho Atlantic Richfield .
Corporation (ARCO) in 1977. ARGIfoperated the smelter from 1977 to 1980
aad eontlnues to ovn the former smelter site and surrounding areas near
Hill Creek through its Anaconda Minerals Company operating unit.
Ort and concentrates vere processed in the Old Vorks, Arbiter, and Vashoe
Vorks at various times bcttimirlMi and 1980. Ore processing to anode
copper produced vastes that have spread over more than 6,000 acres and
contain elevated concentrations of arsenic, cadnium, eopper, lead, and
sine. ARCO has estimated that the vastes include about 185 Billion cu.
ydr«~ of tailings, 2? »H«iTW'slag, and 0 .23 million
cu *	1 /"~*' *Of vaste piles of these materials in
relation to the community of Mill Creek are shovn on Figure 3.
The Anaconda Saelter site vas listed on the National Priorities List (N?'_N
on Septeaber 8, 1983 (68 Federal Register 40638). Contamination of the
coaaunlty of Mill Creek vas identified as a problem during the Phase I
reaedial investigation. The community has been contaminated from ovei 1
years of soflttrMissions, Wflrtve Missions of flue dust located »*
saelter, and continued fugitive eaissions from adjacent highly contam;-a*e:
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soils. Ouring soil sampling of communities in the vicinity of the snelter.
in accordance vich CEKCLA Section 106 Administrative Order on Consent
(CSRCLA-VIII-8A-06), it was discovered that Hill Creek Had extremely hiyh
levels of arsenic and other heavy metal contaainants vhen compared to otner
eooaunities in the area.
The Canter for Disease Control (CDC) showed that pre-sehool children fro*
the coaaunity of Hill Creek had greater arsenic exposure than children of
another coaBunlty in the Anaconda area. This conclusion vas made after COC
conducted urine saapling in March 1983. Sampling vas continued in July of
198S. This urine survey shoved that a COC atteapt to reduce exposure to
house dust in Hill Creek did not reduce the children's urinary arsenic
levels, and the levels m the Hill Creek children regained higher than
those of children in any other coaaunity studied. These elevated urinary
arsenic levels persisted in spite of house cleaning efforts designed by the
COC and recoaaendations by both COC and EPA to residents on hov to reduce
exposure of children to contaminated materials.
NtfartSMr irsssie levels in Hill Creek decreased after several residents
vere relocated* No persons tested after the move had urinary arsenic
levels above SO ug/1, a concentration vhich CDC considered to be a "level
of concern". The fact that children's urinary arsenic levels before the
move vere so ouch greater than the levels for adults is consistent vith the
hypothesis that children can serve as a sentinel population in certain
clrcuastanees.
A detailed, quantitative enda&forMat assessment vas prepared by Clement
and Associates, Inc. for Hill Creek, Hontana (1ft April 1916?. This
assessftoat evaluated the actual and potential exposures of the residents in
Hill Creek to haiardous substances through soil, air. drinking vater. and
household dust pathways. The results of this study and the COC study led
EPA'Mt~AeVlon Heaorandua on April 29, 1986. requesting funding to
teaporWfIfHfrotSSiilgft risk residents of Hill Creek and remo/e the* fr?m
the threat of harmful exposure posed by the Anaconda Smelter site.

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Residents of fourteen households have been temporarily relocated under this
action. A urinary arsenic survey was conducted after residents vert
relocated In the Fall of 1986. Mean urinary arsenic levels in Mill Creek
decreased after residents vere relocated. Although 3 individuals had
urinary arsenic levels above 50 ug/1 (considered to be a "level of
concern") prior to the aove, none had urinary arsenie levels above SO ug/1
after relocation froa Hill Creek. The CDC stated that strietly speaking,
one cannot infer froa the data that excess arsenic exposure has eeased,
except for around the tiae of testing. Nevertheless, CDC believes that
their sampling vas representative oi exposures generally occurring in our
study population and that the relocation has effectively decreased
exposure. The quantitative endangerment assessment was revised in October
of 1987 and continues to indicate significant risks.
Za July 1986, AHC agreed to iapleaent an expedited RZ/FS focusing on the
human health Issues only. Subsequent operable units (regional soils and
regional ground vater) will completely address other issues and other areas
of the Anaconda Smelter site. This expedited RZ/FS vas conducted under a
CStCLA S106 Administrative Order on Consent (Oocket No. CERCLA VZXX-86-C")
During the conduct of the RZ/FS, ARCO negotiated vith the Hill Creek
residents to permanently relocate thea froa the town. ARCO has
successfully reached agreement vith all but eight of the families and
continues to negotiate vith those remaining.
B. Quantity. Type, and Concentration of Hazardous Substances Present
The principal waste sourees that have contributed to contamination in Mill
Creek are the result of Anaeonda Saelter operations that have occurred for
nearly 100 years. These sources include historic stack and fugitive
emissions and ongoing fugitive eaissions froa eontaainated areas
surrounding the Anaconda Smelter. Information on arsenic and heavy metal;
concentrations (ug/g) of the various vaste sources is listed bclc.

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Arsanie
Cadmium
Lt«d
Flue dust
Slag
Opportunity Tailings
49,900-69,600
498-3,190
36-335
1,130-1,300 9.790-U.6C0
4.4-44	364-4,310
1.3-46.3	<10-2,290
Analysis of soil, dust, air, and vatar saaplas collaetad to data ac the
Mill Craak slta shov axtanslva contamination by Anaeonda Smaltar vast as.
Of primary eonearn art alavatad eoncantratIons of arsanie and haavy aatals
in soils, drinking vatar, and housahold dust, with eorrasponding alavatad
urinary arsanie lavals of ehildran (tvo to six yaars old) in Hill Craak.
C. KNOWN OR SUSPECTED RISKS
Tha community of Hill Craak was originally eomprisad of approxiaataly 36
housaholds and had a parmanant population of lass than 100 paopla. As a
rasult of tamporary ralocatlon afforts by EPA and ARCO's buyout program,
only 8 rasidancas ara eurrantly occupiad. Tha risk astlmatas suamarizad
balov ara basad in part on tha assumption that ehildran batvaan tha agas of
ona to six yaars old ara living in Hill Craak, Montana. This vas tha cast
until tha summar of 1987 whan ARC0 voluntarily parmanantly raloeatad tha
familias with ehildran of that aga. EPA has continuad to usa tha
assumption of tha prasanea of ehildran baeausa of tha potantial that
additional ehildran could mova into Mill Craak or b« born in Mill Craak.
EPA hmaldantifiat significant publie haalth risks for ehildran and adults
post# by axposurt to arsanie and haavy m«tal*-to soit^frtnfrfft# vatar, air.
tha community of Mill Craak. Tha toxieologleal
propartias of arsanie, eadmium, eoppar, laad, and sine ara fully discussed
in tha Mill Croak andangarmant assassmant.
Aramnfrc ii a know earcinogtfl- that has baan assoeiatad with an meraastd
fraquaney of skin canear vhan lngastad, and lung eanear whan inhalad.
Cadmium has baan assoeiatad with an ineraasad fraquaney of lunp cancti in
-14-

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huaans when inhaled. Arsenic and eadaiua can be aeutely or chronically
toxie, andean be fatalMf ingested or inhaled in sufficient quantities bi-
tumens, livestock, and wildlife.
Other hazardous substances of concern at the site include lead, eopper, and
sine. Laad is a euaulative poison which ean eause neurological, kidney,
and blood cell daaago in huaans. Soae lead coapounds are also animal
carcinogens adversely affecting the lungs and kidneys. At elevated levels,
soaa eopper and tine coapounds are toxic to a nuaber of aniaal species,
including huaans. Copper and zinc are particularly toxie to fish. Severe
illness and/or death ean result froa exposure of huaans, livestock, and
wildlife to toxic levels of arsenic, eadaiua, and lead.
Currently, there are no uniform national standards identifying what
eonstitutes a hazardous level of arsenic in soil. Therefore, it was
necessary to estimate the levels of carcinogenic risk posed by potential
exposure to arsenic in the community of Hill Creek, Montana.
m
The catclnotenie risk was calculated in aeeordance with EPA's current
guidelines for carcinogenic risk aactuaaent." The cancer potency factor vas
multiplied by the average lifetime exposure in ag/kg/day, to yield
estiaates of lifeline excess risks of cancer resulting froa exposure.
Geometric aean concentrations of arsenie, eadaiua, and lead in each aediu?
vere used in averago ease risk estiaates, whereas aaxiaua concentrations
for these substances in each aediua were used in reasonable maximum risk
estiaates. For arsenie and eadaiua, daily eheaieal intake for soil
ingestion, drinking water, and the non-respirable fraction of the
inhalation pathway were suaaed in order to deteraine euaulative exposure
for eaeh substance. In the case of lead, a multimedia exposure model
developed in the Hill Creek endangerment assessment was used to linearly
estiaate average and reasonable maximum blood lead concentrations in
children. Finally, the cumulative risk estiaates for individual substance;
vere used to assess potential risks associated with multiple chemical
exposures. Carcinogenic risks for multiple chemical exposure were
-15-

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deterained by adding cadmium and arsenic lung cancer risks. Because of the
difference in the tvo target organs, potential skin cancer risks associated
with arsenic ingestion vere considered independently froa lung cancer
risks.
Non-carcinogenic risks for multiple cheaical exposure were est mated by
calculating a euaulative hazard index for ingested cadaiua, and inhaled or
Ingested lead.
Using this approach, EPA evaluated the risk associated with the no action
alternative for the Hill Creek operable unit in the October. 1987 Revised
Final Endangeraent Assessaent for Mill Creek, Montana. Using the average
exposure scenario, the excess risk froa all exposure pathways of developing
skin cancer In Hill Creek it 1.3 s 10 Siallarly, for the reasonable
aaxiaua exposure scenario the exeess skin cancer risk	t0"3. With,
respect to lung cancer froa all exposure pathways, the exeess eancer risk
for the average and reasonable naxiaua exposure seenarioa£4pl*lQ*--' and
r-.ri r»	«	t • -	«-
l3mrlQ"s respectively.
The euaulative hazard index for cadaiua ingestion and lead exposure ranged
froa 0.73 In the average ease analysis to 1.96 in the reasonable naxlmua
case analysis. The hazard index assuaes staple additivity of effeets and
provides a nuaerical indication of the nearness to acceptable Units of
exposure or the degree to vhich acceptable exposure levels are exceeded
(U.S. EPA 1986a). A hazard index greater than 1.0 suggests that exposure
to an individual substance or all substances collectively exceed a
generalized level of concern for a coaaon toxicological endpoint or targe;
organ.
SPA has concluded that the elevated arsenic levels in the urine of the
children formerly living in Hill Creek demonstrate that they were exposed
to elevated levels of arsenic and other metals associated vith the smeltti-.
The estlaated rate of intake of arsenic (estimates reinforced hy the
arsenic levels found in their urine) suggests that the children's exposure.
-16-

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Record of Decision. EPA also considers the cuaulative carcinogenic and
toxle risk posed by ingestion of arsenie, lead, and eadaiua in soil;
drinking vacar; and inhaled and lacar svalloved particulate utter to
independently warrant reaedial action. Significant risks of lung caneer
froa inhalation of arsenie and eadaiua also varrant action.
the contaaination of the Mill Creek area poses an iaainent and substantial
endaageraent to the health of any children vho Bay reside there (Cleaent
1987). Exposura of adults to ingestible foras of arsenic in dust, soil,
water, and food in the Mill Creek coaaunity vould aost likely result in
additional elevated cancer risks. Exposure to eadaiua and lead in soil and
dust aay also have adverse effects on huaan health and the environaent.
0. Extent of Contaaination
Ceataalaatlon of soils in the coaaunity of Mill Creek 1* widespread. A
nuaber of investigations have been eondueted to deteraine the spatial and
vertical distribution of arsenic and heavy aetals in soils in and around
the coaaunity of Hill Creek. An inventory of soils studies for the Mill
Creek RI/FS is provided in Table 1. Results of soil analyses for Hill
Creek and surroundlnf coaaunities are suaaarized In Table 2. .The geoaetric
aean concentration of arsenic, eadaiua, and lead in Mill Creek surface
soils are ftSIF^/ViV 29 af/kf, wutfXM ag/k#f These aean values are
substantially higher than those for surrounding coaaunities (Table 2).
The spatial distribution of eontaainants in the Hill Creek area is sooevhat
heterogeneous> but vldespread. Figures 4, 5, and 6 illustrate the
distribution of arsenic, eadaiua, and lead in surfaee soils in the Hill
Creek area.
Soil profile saaples were also collected by ANC as part of the Hill Creek
Rl/FS. Suaaary statistics for arsenic, eadaiua, and lead in soil profile
saaples are coapiled in Table 3. Although the profiles vere saapled to
varyinf depths and a fev vere saapled in different lnereaents. the data
-18-

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TABLE
1.
INVENTOR* OF SOILS
STUOIES
FOR HIE HILL CREEK
STUDY
AREA












mm. *1
*





ta*in» a
w+m af

wu


u««l
1 |I«M*I«

•trUaalat
la|U


lala
Witt
|«»l l«a
IH
III

laiflal laalpia*

lavnlli
¦ IM


W« 1 Ml
1
•t r«^|f
I Ml
in mit
fr%U
o
It. U. Ct. Ca.
ft.
m
l*aw»l
«Wp |M|
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f la Mill ir«H ra«"4*»
• >
Cillfirtll
• •If H pTfMWf
1
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fa
HI
fill aa* iImiI,

lallt Half


| «a ¦« Iftftflf,

*Ml|lt€#l





|latm Iiaaffi

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f«l
ilaifl, iliilN m»•<






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ll/ft




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l ••
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U



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m
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• Mil nil

ir
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toalfl tctl

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lda»ilK III

0



ta-lt

• ••1


| («a|«f Hill








l»t*» Ink
Mill (rM
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ti
l^f llll |l«tl Mil at Mil
l-»
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It. U, Ca. ft,

¦a


•l/ll #««f

VI
(fMl Nrl M M ^
-------
shov siailar trends. Arsenic is concentrated In the top six inehes. In
the majority of the soil profiles, arsenic concentrations are belov 100
ag/kg at 18 inches, and approach background levels established for this
area belov 42 inehes.
For eadaiua and lead, the highest concentrations are also found in the top
six Inches of the profiles. Hovevar, cadniuo and lead concentrations
decrease aore rapidly vith depth than do arsenie concentrations. Zn the
aajority of the profiles, eadaiua levels are less than detection liaits
(1.2 es 1.3 ag/kg) belov nine inches, and lead levels are vithin the range
of background concentrations belov six inehes.
Quarternary alluvial deposits underlie the Hill Creek site and supply
doaestie veil vater for the area. THir. vater table beneath (fill Creek is
generally 20 feet or deeper belov the ground surfaee depending upon
seasonal flov. DoMtglc tap vater in Hill Creek ha» been stapled on three
occasions*' The first sampling occurred on December 5 and 17, 1985, and the
second on Hay 20 and 21, 1986, and a third set of samples vare collected on
Harch 24 and 23, 1987.
Results of vater analyses are shovn in Table 4. All household tapvater
analyses Vgtfc-Vltblfr tf.S. EPA primary drinking vater eriterla and State of
Montana ptfHpSRHHpwtter standardsrfiir-arsenic, eadaiua, and lead.
Bovever. during the May 1986 sampling, seven household vater supplies ware
found to hava detectable arsenic levels (Table 4). Cfttfaloa and leed
concentrations vera generally at or belov detection Haiti. From a
aultiple exposure standpoint all contributions to arsenie exposure are
important to consider. It is likely that veils yielding arsenie
contaainated voters are loeally contaminated from soils introduced into :!ie
veils•
Hill Creek, the aajor surface drainage system in the area, vas sampled fo-..
tlaes betveen April 1985 and April 1986, as part of the smeltti
investigation. Sampling station locations are shovn in Figure 7. Arsen::

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Is consistently present in Hill Creek in concentrations above the
analytical detection limits (4 ug/1). Concentrations of total arsenic
range betveen 12 and 32.2 ug/1. Zinc has also been detected; values ranged
up to 18 uf/1.
Streaabed sediaents vere saapled in Hill Creek in April and July 1985, as
part of the Anaeonda Saelter Reaedlal Investigation. Traee aetal
concentrations in the streaabed sediaents vere consistently lover than in
the surrounding soils.
Airborne release of hazardous substances occurred during saelter operations
at the Anaeonda Saelter. Fugitive transport of dust containing hazardous
substances froa the site persist even after saelter shutdovn in 1980. Of
aajor concern are releases of arsenic, cadalua, and lead because of the
potential huaan health hazards associated vith these eoapounds.
Until the fugitive transport of hazardous substances froa the Saelter Bill
area into the Hill Creek area is remediated, th* continued eontaalnation
(or teeontaaination) of the area will occur at a r*t»*of J.3 ug/kg soil per
ytsc^ This potential for continued huaan exposure and recontaaination
greatly reduces the effectiveness that other alternatives involving soil
excavation (i.e., clean up of the site) aight have. Recent Hi Vol air
saapling data indicate that highly contaainated particulates continue to be
deposited on the eoaaunlty despite the efforts to eontrol source materials
on Saelter Bill.
tat retire collected at four locations in
the vielaity of the Anaconda Saelter site using Hi-Vol saaplers. The
locations of these saapling stations are shown on Figure 7. Samples
collected at these sites vere analyzed for
(TSP), ratj^nb^l^rticalato; an*«^^ggi||pBerj The aean and range
of concentrations of arsenic, cadmiua, lead, copper, and zinc in airborne
particulate saaples collected at each statiofl during 1984 are shown on
Table 6.
-27-

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A review of current air quality data vas	conducttd to establish background
concentrations for arsenic, cadmium, and	lead. The following estimates of
background levels vere established based	on data eolleeted by the states of
~rixona, Montana, Utah, and Washington.
Sloaont
Arsenic
Cadaiua
Lead
In general, arsanle data collected at the Highway Junction ¦onitoring
station located ooa4 of Anaconda vaa a factor of ten (0.1 ug/a^) greater
than tb* background concentration.' On Deceaber 29, 198* a aaxiaua of 2.0
ug/a* of arsenic vas aeasured at the site. A aaxiaua concentration of
0.681 ug/a^ vaa aeasured at the Hill Creek aonitoring station. The
geoaatric aean concentration for the Hill Creek station vas 0.015 ug/m3
(Tablj S).
No regulations spocifieally applicable to arsenic and cadaiua that are
applicable to the Mill Creek RX/FS curently exist under the Clean Air Act
or the Toxic Substances Control Act.
nn|i1ei collected in selected hoaes in Hill Creek indicate
that elevated levels of arsenic, lead, and cadaiua are present. Daily
exposure to those haxardous substances in household dust is likely.
Results of vacuus dust and indoor respirable dust saapling are suaaarized
in Table 6.
E. Surface and Subsurface Pathways of Migration
On the basis of the available data on environaental levels, it can be
concluded that the soil in the Tovn of Mill Creek is highly contamin*ted
with arsenic and other toxic aetals derived from the Anaconda Smelter s::e
Significantly elevated levels of arsenic have also been reported at tnes
ug/m"
0.01
0.01
0.0*
-31-

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TABLE 5. ARITHMETIC AVERAGE AND GEOMETRIC MEAN CONCENTRATIONS
OF TOTAL SUSPENDED PARTICULATES, ARSENIC, CAOMIUM,
AND LEAO AT MILL CREEK (ug/m^)*

Arithmetic
Geometric
Range of
Concentration

Average
Mean
Minimum
Ma *imun
Total suspended
particulates
27
19
3
187

0.039
0.015
0.001
0.681*
Cadmium
0.004
0.002
0.001
0.112
Lead
0.03
0.02
0.01
0.22
a April, 1984 through March, 1986, e*clud1ng data collected during the :
Creek Park construction, October 2, 1985 through October 22, 1985.

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TAJII 6. MEAN CONCENTRATIONS AND RANGES OF TRACE ELEMENTS IN
RESIDENTIAL DUST AND INDOOR AIR

Residential Dust
(Vecuuaed)
Mg/Kg Arsenie
Ave (Range)
Indoor Resplrable
Arsenic (ug/m )
Ave (Range)
Mill Creek
26*
0.019

(104-336)
(0.011-0.131)
Anaconda
S<
0.007
Opportunity
62
0.003

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A public aeetlng v«j held on December 23, 1986, to inform the public of the
availability of the Draft RI/FS reports for Hill Creek. The public comment
period of the Draft RI/FS was scheduled froa Deceaber 23, 1986, to February
4, 1987. The eoaaent pariod was axtandad froa Its originally scheduled
period to January 20, 1987.
Ray concarnj ragarding tha remedial altarnativas eonsidarad in tha FS are
addressed in the Responsiveness Summary (attaehed).
The State of Montana and the Federal Eaergeney Hanageaent Agency (FEMA)
have eoneurred in the selected remedy.
V. ALTERNATIVES EVALUATION
Hill Creek, Montana is being addressed as an operable unit of tha Anaconda
Saelter NPL Site (40 CFR Subsection 300.68(C)). Hill Creek is a community
of approximately 160 aeres in size vhieh is iaaediately southeast of tha
Anaconda Saelter. The community originally consisted of 37 residences,
hovever, following recent acquisition of properties by ARCO, only 8
residences are currently occupied.
EPA does not intend at this time to address all public health and
environmental problems present in Hill Creek. TMe£fait«*~mmb«v of
rofidwdEr —»m—fT 11'W* ¦dtfifiig la itm Mill Creefc II/PS will be
addressed	operable units*. EPA's primary objective for the
Mill Creek operable unit is protection of the health of the residents of
Mill Creek* This includes both short-term and long-term protection of
public hetlth. Tvo categories of alternatives were presented in the RI/FS
to support this objective: (1) cleanup alternatives, and (2) the permanent
relocation alternative. For the cleanup alternatives. EPA's objective was
permanent protection of public health within the boundaries of the
coaaunity to the aaxiaua jxtent possible at this tiae and to not contribute
to environmental problems. For the permanent relocation alternative. EPn?
objectives are adequate protection of the current residents of Mill Creek
-3A-

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consistent vlth paragraph 121(d)(1) of SARA, supplemented by interim
controls in Mill Creek to Bininise short-tern public health problems for
current non-residents vho My visit or pass through the area. Subsequent
operable units of the Anaeonda Smelter NPL site will address the long term
publie health and environmental Issues associated vith regional
contamination problems.
The selected remedy of permanent relocation of Hill Creek residents,
together vlth temporary site stabilisation* vas determined in the RX/FS to
be a more reliable remedy over the long term. The selected remedial
alternative is required by Section 101(24) of COCLk to be "more
cost-effective than and environmentally preferable to the transportation,
storage, treatment, destruction, or seeure deposition off-site of hazardous
substances or may otherwise be necessary to protect the publie health or
welfare". The National Contingency Plan (NCP) requires that the selected
remedy be "cost-effeetive" and one that effectively "mitigates and
minimises threats to and provides adequate protection of publie health and
welfare and the environment" (60 CFR subsection 300.68(1X1)}. Unless
specified exceptions apply, the selected remedy must attain or exceed
applicable or relevant and appropriate Federal and State requirements.
Remediation of the environmental effects resulting from the existing site
contamination will not be a direet objective of the selected remedial
alternative for Hill Creek. However, implementation of the Mill Creek
remedial response will not cause significant increases in adverse impacts
to the environment. The temporary site stabilisation will provide some
envisonamtal protection. Environmental effects of the existing
contamination vill be addressed in the Anaconda Smelter site RX/FS.
In accordance vith Section 300.68(f) of the NCP, EPA has developed
alternatives which address the following categories:

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to prevent others from building n«v homes in these areas and significant
risk 1avals would reaain for araas whara soil was not reaoved. Soil
reaoval to a dapth of 18 inches throughout Hill Craak was identified as
being lass reliable and having a graatar failura potantial than did
peraanent raloeation or eonplata soil raaoval. Coaplata soil raaoval was
considarad lass raliabla than parmanant raloeation. Several faetors laad
to this last conclusion: 1) long-tera soil recontaaination froa adjacent
non-reaedlated sourees, 2) potantial failura of vafatativa covar and, 3)
potantial for continuad diract eontaet if huaan activity disturbs tha
covar. It vas concludad that tha paraanant raloeation altarnativa is
prafarabla and raliabla in protaeting tha haalth of eurrant Mill Craak
rasidanti. This altarnativa providas adequate protaetlon of tha haalth of
thasa individual (saa Tabla 7). By physically reaoving rasidants, diract
eontaet vith eontaainants is pravantad. Tha raaady is raliabla sinea thert
ara no technical eoaponants to "fall". In faet, urinary arsenie lavels ia
all rasidants that vara taaporarily ralocatad In 1986 have decreased
further indicating the reliability of this alternative.
Cost Effectiveness
A suaaary of the eost analyses is presented in Table 8. The alternative
with the lowest cost is Alternative 1: Relocation of all residents. It
should be noted that AKBTfca* currently relocated all buc.» realdene#*,
leaving a n*fe-eMt;o£ 9300,000 tfr'coapletethia. reaedy.
The cost for Alternative II does not, however, include the eost of soil
cleanup, la the Feasibility Study, the cost of peraanent relocation
including eoaplete raaoval and replacenent of 6 to 42 in. of soil vas
eoapared to slailar soil raaoval and replacenent with the residents
reaalnlng in Mill Creek so that EPA could consider what the total remedial
costs vould be for Hill Creek when the interia reaedy eosts were added to
projected eosts of a potential final remedy. These comparative costs are
suaaarized below:
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Other Federal and State criteria, advisories, and guidance tz ;
considered:
a.	Health based performance goals of 0.01 ug/m- for ar3*r.;-
and O.Oi ug/®3 for cadmium air pollution (natural
background levels based in part on EPA carcinogenic
potoncy factors ("Health Assessment Document lor
Inorganic Arsenic" March 1984, E?A-600/8-83-025i?;
"Updated Mutagenicity and Careinoganicity Assessment :f
Cadmium; Addendum to the Health Assessment Document iz:
Cadmium (May 1981 Juna 1985, EPA-600/8-83-025? ar.d
EJA's targat risk level of 1 x 10"* and risfc ranga c! i
x 10"4 to i x 10"' (Publie Baalth Evaluation Manual,
1986).
b.	Saa Table 5.2-3 of Feasibility Study report.
c.	Other Federal Criteria, Advisories, Guidance and Stats
Standards in NCP at SO Fed. Rag. 47949-47950.
Operable Unit Consistency vith the Final Remedy
Permanent relocation as a first operable unit is consistent viir.
any final remedy that EPA may select at a later date <40 C7?.
Section 300.68(c)). EPA can elect to clean the vacated tsvns::a
in any" manner determined appropriate after the residents have cas.i
relocated.
VI. SELECTED REMEDY
Based on the evaluation of the remedial action alternatives
accordanca vith the MCJ (40 CFR 300.68) and FS guidance,
Alternative Ho. i. Relocation of All Residents, has been
identified as the preferred remedial action alternative.

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Thii alternative involves buyout of all property owners in the town of Mill
Creek and My require condemnation of th« community by the United States or
the State of Montana in order to accomplish the relocation of those
residents vho do not wish to relocate. Deaolition of structures would be
conducted and the entire site would be feneed and posted folloving
relocation of residents.
Temporary stabilization would be performed following deaolition of
structure*. Disturbed areas of the site would be stabilised from eroslonal
forees by establishing and aalntalning vegetation on those areas.
Because the Hill Creek area is immediately adjacent to highly contaminated
areas of the Anaconda Smelter site, there Is potential for continued
transport of contaminants into the area. For this reason, and to ensure
consistency of the remedy for Hill Creek with that for the remainder of the
saelter site, it was decided to consider the final remedy in the Hill Creek
area in conjunction witn the implementation of the final remedy for the
Anaconda Saelter site.
For the detailed analysis of alternatives. Section 300.68(h)(2) of the NC?
specifies that an evaluation of reliability, iaplementabillty, and
constructabllity be conducted. Alternative No. 1 would be the most
reliable alternative, being easily iaplenented with little or no
probability of failure. The alternative is institutionally aanageable.
Condemnation or other legal procedures could be required to implement
coaplete relocation of residents.
The peraanant relocation of all Hill Creek residents is an effective means
of elialnatlnf the publie health threat to the current resident population.
Total relocation of residents would eliainate the pathways of exposure of
the resident population to contaainated soil, water, and air sources. This
reaedy would therefore effectively mitigate and ainiaize threats to and
provide adequate protection of public health on an interim basis-
-<.9-

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Construetability. as such, is not applicable to this action.
Consistent vith procedures in 44 CFH Part 22. tht United Starts vill take
Adequate aeasures to ensure that relocating residents of Hill Creek
relocate in areas vhich do not pose a significant risk to public health.
It is anticipated that exposure to arsenic and heavy metals at the
relocation sites vill be redueed to levels at or near background, making
Alternative No. 1 the reaedlal action alternative vith the lovest risk
using the health risk assunptlons presented in the Endangeraent Assessment.
Having both the lovest risk and lovest eost ($1,700,000 total present vorth
based on aarket value), relocation of all residents is clearly the most
cost-effective alternative. In addition, beeause AHC has aqulred all but 8
residences, approximately $300,000 1% necessary to coaplete the remedy.
The alternative vould also have minimal environmental impacts and vould
be consistent vith any final remedial action.
OPERATION AND MAINTENANCE
¦
O&H requirements for the selected alternative vould be simple and
Infrequent, involving maintenance of fencing and varning signs around the
site boundary. Labor requirements for fence and sign aalntenanee vould be
ainlaal as vould materials for repair. The reliability of site
stabilization of areas disturbed ducing demolition activities vould be
dependent on the successful establishment of vegetation on these areas.
Certain areas may have levels of contaminants present that vould be
phytotoxlc. It is anticipated, hovever, that most disturbed areas can be
teaporarily revegetated, although soil amendments aay be necessary. The
aaount of barren soil remaining in Hill Creek after temporary site
stabilisation activities vould be minor compared to adjacent areas on
Saalter Bill.
-31-

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Anaconda Smelter
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Remedial Action Plan, Mill Creek, Montana;
Undated

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EXHIBIT 3
Remedial Action Plan
Mill Creek, Montana
I. General
The Defendant shall implement a program to temporarily
stabilize vacated areas of the community of Mill Creek as
residents are relocated. The temporary stabilization
requirements are intended to provide temporary protection of
public health and the environment pending completion of a
Remedial Invest 1 gat 1on/Feas1b111ty Study ("RI/FS") for a
later operable unit for regional soil contamination around
the Anaconda Smelter complex (Including the area of Mill
Creek, Montana) and selection of a final remedial action. In
conducting the temporary site stabilization, the Defendant
shall comply with the requirements of section II of the
Remedial Action Plan set forth below.
11. Temporary Site Stabilization Program
A. As title to property 1s transferred to the Oefendant by
the residents of Mill Creek or the State, homes and associated
buildings shall be demolished on the property and driveway
asphalt paveaent shall be rendered unsuitable for recreational
bicycling, skateboards, etc., through pitting or other means
of roughening the surface. For properties acquired from
residents by the Oefendant, this shall be accomplished within
fourteen (14) calendar days of cessation of utility service
to the acquired residence or as quickly as practicable during
the non-construct1 on season (November 1 to April 30).

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60 days of the date of entry of this Partial Consent Decree
or access to property, whichever 1s later.
c.	Following a finding by EPA and the SHPO, in
relation to the criteria for listing in the National Register
of Historic Places, if a structure 1s found to be not eligible
for nomination Into the National Register of Historic Places,
no further action is necessary. The Defendant shall proceed
with demolition of all buildings on acquired properties within
fourteen (14) calendar days of cessation of utility service
to the acquired residence or as quickly as practicable
following cessation of utility service during the non-
construction season.
d.	If structures are found by EPA and the SHPO to
be eligible for the	i
then the ef feet* the |ii 			 RUMWltH I JIM 11 H ¦
determined by EPA and the SHPO using the criteria of effect
(section 800.9(a)) and the criteria of adverse effect (section
800.9(b)). If a finding of adverse effect 1s made, EPA shall
consult with the SHPO and the Advisory Council on Historic
Preservation to determine an appropriate aporoach to mitigate
the effects of the Mill Creek demolition. Upon approval of a
Memorandum of Agreement Including mitigation matters by the
Advisory Council, the Memorandum of Agreement shall be
incorporated into this Partial Consent Decree as an enforceable
part thereof, and the Oefendant shall comply with the
mitigation measures set forth therein.

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V 1 1
The following reasonable precautions apply to the Mill Cree*
demoli 11 on.
Building Demo 111 i on
All nouses and structures in Mill Creek must be wetted
with water Inside and outside prior to building demolition.
At the time a structure is demolished, a dust-suppressing
mist shall be applied to control airborne particulates.
Roads and Work Areas
All haul roads shall be watered during the construction
season (May 1 to October 31) as often as necessary to prevent
excessive dust. "Excessive dust" means airborne particulate
emissions which exceed 50 percent opacity for a period of
90 seconds. When watering will not cause safety problems,
all work areas shall also be watered.
Transport of Demolition Debris
Demolition debris shall be wetted in the trucks prior to
1eavlng Mill Creek.	to
It will be consolidated with demolition
debris froa the Smelter Complex located between the Anaconda
#1 tailings pond and the slag pile. Debris shall be covered
with slag to prevent blowing dust pending final disposition
of demolition debris following the Smelter Hill RI/FS.
EPA has concluded that since the actions in this Remedial
Action Plan are of short and intermittent duration and are
intended to be Interim, and since releases from these actions
are difficult to separate from releases from areas adjacent

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* V 1
(14) calendar days after the start of the next construction
season.
C . Maintenance
The Defendant shall maintain the temporary cover over
the demolition debris, the temporary vegetative cover, and
che security fence until such time as EPA, 1n consultation
with the State, completes the final remedial action for Mill
Creek under subsequent operable units of the Anaconda Smelter
Superfund site. Maintenance shall include monthly Inspection
and any necessary repairs to the fencing, temporary vegetative
cover, and debris disposal site cover.
III. REPORTING REQUIREMENTS
The Defendant shall submit monthly progress reports t-o
EPA and the State not later than seven (7) calendar days
from the end of a calendar month documenting the Defendant's
progress in complying with the requirements of this Remedial
Action Plan. These reports shall address the permanent
relocation program and the temporary site stabilization
program, including operation and maintenance activities.
The reports shall describe proposed activities for the upcoming
month and tht findings of the maintenance Inspection. The
monthly progress reports do not need to include other plans,
reports, or other documents submitted to EPA and/or FEMA
pursuant to this Partial Consent Decree 1f they are clearly
referenced In the monthly report.

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Anaconda Smelter
Mining Waste NPL Site Summary Report
Reference 3
Excerpts From Clark Fork Superfund Master Plan;
EPA and Montana Department of Health and Environmental Sciences;
October 1988

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MASTER PLAN

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dinate Superfund activities with other environmental im-
jvement programs;
2.0 PROBLEM AREA DEFINITION
»provide for consistent approaches to response actions for
all sites;
• communicate information on Supertund activities to all in-
terested parties.
A projected schedule for addressing contamination problem
areas is included in this Master Plan This schedule will, of
necessity, be modified and updated as new information
becomes available and major decisions are made.
1.2 HISTORICAL BACKGROUND
The EPA and the State of Montana are working together in the
Superfund program to seek solutions to the impacts from
hazardous substances (pnmanly metals) left by over 100 years
of mining and processing operations, as well as other in-
dustnal activities. The area of concern includes the Upper
Clark Fork Basin above Warm Spnngs Creek and the main
stem of the Clark Fork River to the Bitterroot River below
Missoula, Montana.
Investigations in the upper Clark Fork area, initiated by EPA
in 1982, resulted in the establishment of four separate but con-
tiguous Superfund sites. The sites are the Milltown Reservoir
site, the Anaconda Smelter site, the Montana Pole site, and
the Silver Bow Creek/Butte Addition site (See Map, page 2).
EPA and MOHES initially identified 77 existing or potential con-
tamination problems at the sites. As descnbed in Section 3,
these problems have been consolidated where possible for
more efficient responses. EPA has provided funds to MOHES
to take the lead for investigations at the Silver Bow Creek site,
the Montana Pole site, and the Milltown Reservoir site. The
Atlantic Richfield Company (ARCO)» conducting investiga-
tions at the Anaconda Smelter site and may undertake work
at other sites. EPA also intends to offer the opportunity to
potentially responsible parties to conduct the investigations
for the Butte Addition to the Silver Bow Creek site under an
enforcement agreement (see Section 4.4 Superfund Enforce-
ment Authorities). EPA is managing response actions for the
Butte Addition.
In an effort to develop an integrated approach tor addressing
these sites, EPA, MDHES, the Montana Governor's office,
representatives from the communities of Butte and Anaconda,
and the Atlantic Richfield Company (ARCO) have provided in-
put to this Master Plan to help define investigation and
remedial priorities and establish a schedule for coordinated
action.
Each Clark Fork Superfund site is compnsed of several ex-
isting or potential contamination problems. The most impor-
tant problems are summanzed for each site in the Appendix
The history and interrelationships of problems among sites are
descnbed further in the narrative below. The major corrective
actions that have already been taken at each site are des-
cribed in Section 13.
2.1 MILLTOWN RESERVOIR SITE
Milltown Reservoir is located adiacent to
Milltown, Montana at the confluence of the
Blackfoot and Clark Fork Rivers. Milltown
Reservoir was created in 1907 as part of a
hydroelectnc power generating facility which has been owned
and operated since 1929 by Montana Power Company The
reservoir has accumulated &5 million tons of sediments
transported by the Clark Fork River and its tributaries
(Woessner et al„ 1984). Unusually high concentrations of
arsenic, lead, zinc, cadmium, and other metals have been
found in reservoir sediments. These contaminants have been
transported from the reservoir sediments into the shallow
ground water that provided dnnking water for Milltown
residents. The reservoir was designated a Superfund site in
September 1983.
2.2 ANACONDA SMELTER SITE
The Anaconda Smelter is located at the
southern end of the Oeer Lodge Valley, ap-
proximately 25 miles northwest of Butte.
Ore from the Butte area mines was transported to Anaconda
and processed at various locations (Old Works, Arbiter Plant,
and Smelter Hill) from 1884 to 1980. Ore processing wastes,
including about 185 million cubic yards of tailings, about 27
million cubic yards of tumace slags, and about 250.000 cubic
yards of flue dust (CH2M Hill, October 1984), are contained
within an area of more than &000 acres and contain elevated-
concentrations of copper, cadmium, arsenic, lead, and zinc.
The Anaconda Smelter area was designated as a Superfund
site in September 1981
Tailings were typically deposited in ponds where solids were
allowed to settle before the wastewater was recycled or
released Into nearby watercourses. These ponds (Anaconda,
Opportunity, Bradley, and Iron) were created by a series of
dikes which have left mounds of tailings as deep as 90 feet.
Theee ponds contain various wastee which have led to ground
water and surface water quality degradation. Additionally,
emissions from the smetter stack have resulted in soils con-
tamination throughout a broad area of the upper valley.

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M

7
/
2J MONTANA POLE SITE
The Montana Pole site encompasses approx-
imately 40 acres immediately south of Silver
Bow Creek at the southwest edge ol Butte.
From 1947 to 1983 the Montana Pole Treating
Company treated poles with pentachloropheno! (PCP) and
creosote at this site in 1983, seepage of these wastes from
the Montana Pole site into Silver Bow Creek was estimated
to be two to five gallons per day The site was designated a
Superfund site in November 1986.
2.4 SILVER BOW CREEK/
BUTTE ADDITION SITE
Following the discovery of
gold in 1864, the Butte area
became an internationally
recognized mining center with over 300 combined copper and
silver mines. 9 silver mines, and 8 smelters in operation dur-
ing 1884 In 1955, excavation of the Berkeley Pit began and
mining continued until 1977. Silver Bow Creek has histoncal-
ly received discharge from mining, smelting, wood treating,
and other industrial sources for over 100 years.
The Silver Bow Creek site was designated a Superfund site
in September 1983. The original site encompassed the
floodplain of Silver Bow Creek from Butte downstream to the
Warm Springs Ponds. Remedial investigations were initiated
within this area dunng 1985. In November 1985, the boun-
danes of the site were expanded to include the Butte area.
Downstream portions of the Clark Fork River floodplain from
Warm Spnngs Ponds to Milttown Reservoir were identified as
an expanded study area.
taminate surface and ground water along Silver Bow Creek
and the Upper Clark Fork River. The Anaconda Smelter site
also has contributed contamination to the Clark Fork River.
2.5 INTERRELATIONSHIPS AMONG SITES
Geographic, technical, and legal interrelationships among
Superfund sites in the Clark Fork Basin dictate that dose coor-
dination will be required dunng implementation of this Master
Plan Due to their geographic proximity, all Superfund sites
are sources of contamination to Silver Bow Creek and/or the
Clark Fork River As a result of this interrelationship, response
actions need to be coordinated so that downstream, down-
gradient, or downwind sites are not recontammated. follow-
ing cleanup, by upstream, upgradient, or upwind sites
Another similarity among these sites is the problem of deal-
ing with large volumes of mining wastes which contain similar
metallic contaminants. The sites also share similar pathways
through which human health and the environment are
adversely affected. Due to geographic proximity and
similarities of waste characteristics, response action criteria
which are established for these sites will be closely related
For the same reason, response actions appropriate at one
mining waste site may also be appropnate at other sites.
All of these interrelationships among Superfund sites in the
Clark Fork Basin require that response actions are carefully
coordinated to ensure that effective solutions are identified
and implemented in an appropnate sequence. The overall pur-
pose of this continuing master planning effort is to ensure that
activities being conducted at individual sites complement
each other and lead to the most efficient response possible
3.0 ADDRESSING OPERABLE UNITS
Today mining, milling, and smelting wastes exist as sources
of soil, water, and air contamination throughout the Butte area.
Contaminated surface water runoff from the Butte area
discharges directly to Silver Bow Creek. In addition,
underground mines in the area are filling and generating acid
water as water levels nse. During active mining, these mines
were dewatered by a network of pumps with some water be-
ing recycled and some being discharged to Silver Bow Creek.
It is estimated that over 3500 miles of underground mine worfc-
ings are interconnected with the Berkeley Pit. These mines
contain approximately 11.2 billion gallons of acid mine water
(CDM 1988). Initial investigations suggest that within eight
years at the earliest, water in the Berkeley Pit may nse to a
level where acid mine drainage could contact the
bedrock/alluvium interface with the possibility tor contamina-
tion of Silver Bow Creek.
In addition to contaminants from the Butte area, the Montana
Pole and Rocker wood treating sites contribute to the contami-
nant load of Silver Bow Creek. Continuous deposits of metals-
laden sediments end tailings lie within the floodplain and con-
In order to manage the interrelated problems identified at the
four Clark Fork Superfund sites, ERA and MDHES have con-
solidated the 77 potential contamination problems into 25
Operable Unite. An operable unit is a dearly defined, smaller
portion of the overall work to be completed at a Superfund site.
Each operable unit is generally investigated and remediated
on an individual basis. The criteria used to designate operable
units are:
•	Areas with similar contaminated media (soils, flue dust,
ground water, etc.);
•	Areas within a similar geographic area;
•	Areas that will be remediated using similar techniques;
•	Areas that will be remediated within a similar time frame;
and
•	Areas that can be managed and addressed as an individual
RI/FS.
-4-

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rfse 25 operable units are sutyect to change as more infor-
mation becomes available. For example, it may be possible
to further consolidate operable units if additional similarities
between individual units are identified, or further investigation
may show that the consolidated operable units must be broken
back down into smaller, more manageable units to carry out
appropnate remedies.
3.1 CRITERIA FOR ESTABLISHING PRIORITIES
Since there are so many Superfund problems to be
addressed, priorities are established to ensure the most
serious problems are dealt with first. The EPA and MDHES
have identified high, medium, and low prionty operable units
according to the sequencing cntena listed in Table 1
Tablt 1:
Criteria for Establishing Priorities for Operable Units
High Priority Sequencing Criteria:
1.	High potential human health exposure
2.	High potential environmental exposure
3.	Provides critical-path data needed to fully address
other operable units
Medium Priority Sequencing Criteria:
1.	Medium potential human health exposure
2.	Medium potential environmental exposure
1 Potential for recontamination of other operable units
located downstream, downgradient. or downwind
4.	Unusually complex problem requiring lengthy
evaluation
Low Priority Sequencing Criteria:
1 Low potential human health exposure
2.	Low potential environmental exposure
3.	Low present human health or environmental ex-
posure but potential future exposure
4.	Low nsk of off-site contamination
The sequencing cntena are ranked according to several fac-
tors. Human exposures are generally given a higher ranking
than other cntena. There is recognition that some human
health concerns pose an immediate health risk that should be
dealt with as a removal action. Other health concerns involve
chronic nsto over a lifetime of exposure that can be responded
to with a later, longer-term action. In total the sequencing
cntena provide for the orderly resolution of human health and
environmental concerns at the Superfund sites.
3.2 RANKING OPERABLE UNITS
Each of the 25 operable units was evaluated against the
criteria shown above and placed into a high, medium, or low
priority category. This ranking is presented in Table 2. Each
of these operable units is shown on the master schedule in
Section &
3J ACCOMPLISHMENTS
A significant amount of work has already occurred on many
of these operable units. This section briefly summanzes the
efforts to date.
3.3.1 Milltown Reservoir Site
in 1983 a Remedial Investigation/Feasibili-
ty Study (RI/FS) was initiated by MDHES
and EPA. Aa a result of these studies. EPA
provided funds tor a new water supply system
for Milltown in 1985. RI/FS activities are continuing at Milltown
under the lead direction of MDHES. These studies will address
the need for, and possible solutions to, the contaminated reser-
voir sediments and ground water at Milltown. In addition, these
studies are being expanded to determine if releases of hazar-
dous substances, pollutants, or contaminants have occurred,
or have the potential for occurring downstream from the
reservoir.
Ikble 2:
Proposed List of Priorities of
Clark Forte Operable Unite
High Priority Operable Unlta
Mill Creek
Walkervtlle
Butte Priority Soils
Old Worka Removal
Flue Oust
Warm Springe Ponds
TVevona Flooding
Montana Pole
Mine Flooding (Berkeley Pit)
Rocker
Medium Priority Operable Unlta
SBC Area I (Metro Storm Drain—Colorado Tellings)
StreameMe TWinge (Colorado TMIInge Warm Springs
Ponds)
Smettar HIR
Clark Fork River
Milltown neeervolr
Anaconda Community Solla
Anaconda Site-wide Ground Water
Oid Works (General)
Low Priority Operable Unlta
Butte Non-Priority Sot is
Tailings (ground water/alluvium)
Arbiter
Smelter Wastes (Beryllium, Slag)
Anaconda Surface Water and Sediment
Agricultural Lands
Active Mine Area
Wbrti on oparabte unm Mmi in boMfaca rwa Dagun: thia inciuon
til niqn pnomy «na mow madtum pnoffly opafawa urna.	
-5-

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Anaconda Smelter
Mining Waste NPL Site Summary Report
Reference 4
Excerpts From Anaconda Smelter Site:
Superfund Progress Report;
EPA Region VIII; June 1990

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fl ANACONDA SMELTER SITE vvEPA
SUPERFUND PROGRESS REPORT
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION VIII — MONTANA OFFICE	JUNE 1990
INTRODUCTION
The U S. Environmental Protection Agency (EPA) and
the State of Montana continue to work cooperatively in an
effort to improve the environment m the Anaconda area.
Progress reports will provide periodic overviews of the
Superfund activities and important documents in the study
and cleanup of the Anaconda Smelter Superfund Site. This
progress report and others will include information on issues
of interest upcoming site activities and meetings, and ways
to obtain further information.
Public involvement is an important part of the Superfund
process and is encouraged by the agencies. EPA and the State
invite the public to offer suggestions forthe types information
they would like to see included in future progress reports.
SITE DESCRIPTION: —
The Anaconda Smelter site, located at the southern end of
the Deer Lodge valley, is the location of the former Anaconda
Minerals Company (AMC) ore processing facilities. These
facilities were developed to remove copper from ore mined in
Butte during the period from 1884 through 1980. The smelter
closed in 1980. The Atlantic Richfield Company (ARCO)
bought AMC and is considered the potentially responsible
party (PRP) at the site.
The smelting process produced wastes with elevated
concentrations of arsenic and metals such as copper, cadmium,
lead, and zinc. These contaminants pose potential risks to
human health and to aquatic organisms in nearby streams.
ARCO has esnmated that the wastes include approximately
185 million cubic yards of concentrated tailings, about 27
million cubic yards of furnace slag, about 300,000 cubic
yards of flue dust, and tens of square miles of contaminated
soils.
Because of the size of the processing facilities, the 100
year period of operation, the large volume of wastes produced,
and the wide area over which the wastes were dispersed, the
Anaconda Smelter site has been divided into smaller more
manageable areas, or "operable units". Operable units are
geographical areas with similar contamination which allow
EPA to address the areas of greatest concern to public health
and the environment first. The operable units are defined on
the insert and identified on the corresponding map.
BACKGROUND
An assessment of the pollution problems associated with
heavy metals releases led to listing of the site on the National
Priorities List (NPL) of Superfund sites m September 1983
In October 1984 ARCO entered into an administrative order "*
on consent to conduct thirteen remedial invesugaoons on the
Anaconda Smelter site.
During early stages of the smelter investigations it be-
came apparent that the community of Mill Creek had the
highest levels of contamination of any inhabited area around
the smelter. Children in Mill Creek were found to have
elevated urinary arsenic levels indicating an excess exposure
to arsenic in their environment. This information led EPA to
focus remedial investigations on Mill Creek. Young children,
the group at greatest risk, were temporarily relocated in May
of 1986. Following the temporary relocation none of the
individuals involved showed elevated urinary arsenic levels.
Flue dust, the most concentrated contaminant on the site, was
covered with a surfactant and din roads in the community
were paved to reduce inhalation exposures.
In My 1986 EPA entered into an administrative order on
consent with ARCO to conduct an expedited remedial in-
vestigation and feasibility study(RI/FS) for Mill Creek. The
Record of Decision (ROD) for Mill Creek was completed in
October 1987. The selected remedy was the permanent
relocation of Mill Creek residents. This remedy was selected
in pan because the area had the potential to become
re contaminated. EPA successfully negotiated a consent de-
cree with ARCO for the implementation of the relocation of
Mill Creek residents on January 7, 1988. Relocaoon was
completed in the fall of 1988.
In October 1988, EPA entered into an administrative ^
order on consent with ARCO to conduct additional remedial
and removal activities at the smelter site. Remedial investiga-
tions for the Flue Dust and Smelter Hill operable units were
initiated, as well as the initiation of a removal analysis forthe
Old Works and Community Soils operable units.
In March 1990. EPA and ARCO amended the October
1988 Administrative Order on Consent to conduct an addi-
tional removal analysis at the Arbiter and Beryllium operable
units. In addition. EPA and ARCO agreed to conduct a siting ^
analysis for a waste repository on the Anaconda Smelter site.

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jRRENT SITE ACTIVITIES
MILL CREEK OPERABLE UNIT
Current Activities
The only ongoing activity at the Mill Creek operable
unit in addition to fences and warning signs is mainte-
nance of the vegetative cover over the areas of demol-
ished buildings.
SMELTER HILL OPERABLE UNIT
Current Activities
Field work, initiated last summer, is nearly complete
for the vegetation and plant toxicity, ground water,
surface drainage, and soils investigations on Smelter
Hill. These investigations are intended to fully charac-
terize contamination within the former smelter complex.
Several thousand samples have been collected with the
remaining soil sampling to be completed this summer.
The soil sampling plan is currently being modified to
reduce the number of samples needed. This modification
will allow the project schedule to be accelerated and
allow for additional sampling to be conducted on other
operable units this field season instead of next year.
Initial alternatives and treatment technologies are
currently being looked at. Upon completion of the field
sampling and screening of alternatives, EPA will com-
plete and release to the public a data summary report and
an initial alternatives screening document If necessary,
additional sampling and/or treatability studies will be
conducted next field season. Treatability studies provide
information on how well an alternative will work.
Projected Activities
•	Amend existing work plans and sampling plans,
June 1990
•	Conduct field sampling, June 1990 • September
1990
•	Technology scoping document. Summer 1990
•	Site characterization report. Winter 1990-91
•	Initial alternative screening document. Spring
1991
FLUE DUST OPERABLE UNIT
Current Activities
EPA and ARCO are working to evaluate technolo-
gies to reduce the mobility of flue dust compounds
currently stored on the site. These treatability studies are
nearing completion. The preliminary draft Remedial
Investigation/Feasibility Study Report is expected to be
completed late this summer. The final draft RI/FS and
public comment period will be this winter, with the final
RI/FS report due by early Spring 1991. A record of
decision could be reached as early as the fall of 1991.
Projected Activities
•	Preliminary draft RI/FS, Summer 1990
•	Final draft RI/FS and public comment period.
Winter 1990
•	Final RI/FS, Spring 1991
•	Record of decision. Fall 1991
•	Cleanup action, 1992 field season
OLD WORKS REMOVAL OPERABLE UNIT
Current Activities
Investigations for flood plain wastes, waste piles,
surface water, and borrow material, conducted during
the summer of 1989, are nearly complete. A few tailings
samples from near the arbiter plant will be collected this
spring. EPA will present results of the Old Works
sampling effort in a data summary report later this
summer. A preliminary nsk assessment and analysis of
the applicable or relevant and appropriate requirements
(ARARs) will be released by early fall 1990.
The agencies and ARCO will identify and screen
removal alternatives this summer and release them to
the public this fall. Following the screening of alterna-
tives the engineering evaluation and cost analysis (EE/
CA) will be completed. The final draft EE/CA will be
released to the public for comment this winter. Follow-
ing public input, EPA will make its decision on the
appropriate removal activity. Initiation of cleanup ac-
tivities are anticipated for the 1991 field season.
Projected Activities
•	Data summary report, Fall 1990
•	Preliminary risk assessment. Fall 1990
•	Analysis of applicable orrelevant and appropriate
requirements (ARARs), Fall 1990
•	Draft EE/CA report, Fall 1990
•	Public comment period. Fall 1990
•	FinalEE/CAreportandEPAdecisiondocument,
end of 1990
•	Cleanup actions, 1991 field season
COMMUNITY SOILS REMOVAL
OPERABLE UNIT
Current A ctivities
Phase I sampling was completed last summer in the
Teresa Ann Terrace, Cedar Parks Homes and Benny
Goodman Park. Preliminary data indicate that those
areas were not built on former tailings as previously
3-

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ANACONDA SMELTER OPERABLE UNITS
MILL CREEK The Mill Creek operable unit is
located 1.5 miles east of Anaconda, adjacent to the
S melter complex. Mill Creek was formerly a community
of 37 families whom EPA relocated because of unac-
ceptable risks to human health from past smelter emis-
sions.
SMELTER HILL The Smelter Hill operable unit is
located immediately east of Anaconda and is also referred
to as the "new works" or "Washoe Smelter". The Smelter
Hill operable unit encompasses approximately 4 square
miles of property primarily owned by ARCO. In general,
the site includes the former process area, the gate area
west of the slag pile and ARCO-owned property located
upgradient from Mill Creek, including the Smelter Hill
railroad loop.
FLUE DUST Flue dust is a fine dust separated from
the flue gas during smelter operations and contains
extremely high concentrations of arsenic and metals
including cadmium and lead. Flue dust is located at
various locations around Smelter Hill.
OLD WORKS The Old Works area is the site of the
first smelters in Anaconda generally referred to as the
"Upper and Lower Works". EPA has identified two
operable units, one to address removal of waste sources
and streamside tailings and one to deal with the remain-
ing area and contamination. The Old Works removal
study area specifically includes the 100-year floodplain
of a 2-3/4 mile stretch of Warm Springs Creek, the areas
around the Upper and Lower Works and waste sources
at the Old Works. The Old Works remedial study will
address the areas mentioned above as well as tailings in
the historic flood plain of Warm Springs Creek and
surrounding soils contaminated by Old Works pro-
cesses.
ARBITER The arbiter plant is located approxi-
mately one mile east of Anaconda, adjacent to and south
of Warm Springs Creek. The arbiter plant was a copper
refining plant designed to produce cathode copper from
sulfide ores using an ammonia leach. The plant operated
briefly from August 1974 to November 1977. Wastes
produced by the plant, including arsenic, cadmium, lead
and zinc, were slurried to disposal ponds adjacent to the
plant. Ongoing removal studies are focused only on the
disposal ponds and bunkers.
BERYLLIUM DISPOSAL AREAS Beryllium is
a highly toxic chemical element used primarily as a
hardening agent in alloys. A beryllium flake-metal pilot
plant and a beryllium oxide pilot plant were operated on
Smelter Hill between 1964 and 1968. Immediately fol-
lowing plant closure and during the initial clean up
operations in 1968, AMC stored wastes and contami-
nated materials in drums and disposed of them in the B-
2 section of the Opportunity tailings ponds. Additional
clean up and decontamination of the beryllium pilot
plant occurred in 1972 and those wastes were disposed
of in a bunker on Weather Hill.
COMMUNITY SOILS This operable unit targets
soils contaminated by smelter emissions in the commu-
nities of Anaconda, Opportunity, Warm Springs, Galen
and Deer Lodge. A community soils removal project is
currendy underway in Anaconda at Teresa Ann Terrace,
Cedar Park Homes and Benny Goodman Park. These
areas were initially targeted because of their close
proximity to the Old Works area and Smelter complex.
SLAG The slag piles are one of the most visible
wastes in the Anaconda area. Slag, a dark coarse-
grained material, is refuse separated from metal during
the refining process. Slag piles are located next to the
Anaconda tailings pond and industrial buildings on
Smelter Hill and at the Old Works.
TAILINGS/ALLUVIUM The smelter tailings
make up the largest volume of waste at the site. Tailings
from the smelter process were deposited in the Ana-
conda and Opportunity ponds and tailings fields which
stretch from Anaconda to the Warm Springs Ponds.
REGIONAL SOILS This operable unit addresses
contaminated agricultural lands surrounding the smelter.
REGIONAL GROUND WATER This operable
unit addresses the groundwater contamination associ-
ated with the site.
SURFACE WATER AND SEDIMENT Past
mining and smelting operations resulted in the release of
metal-laden tailings and sediments into regional streams
such as Warm Springs, Mill and Willow Creeks. This
operable unit addresses streams affected by the site.


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Anaconda Superfund Site Operable Unit Locations
AcUtuim Lt|tod
Key
FntUlUi tmi
—	liUrmllUat Jlnu
~ Prtairr Rlfkmr
—	Iiwlir;
ran
era a/3
faaa/d
[TO B/W IMn>
Warm
Springs
Arbiter and
Beryllium
Vastes
Old Works
*~*^g£Opportunity Ponis><&
Warm
Springs Ponds
Mill-Willow
Brpass
K&5*9
2viVip
macondafl
f£g£m
naconda
3pp< rtui lit jrf
/
Flue Dust
Sites
Hill Creek

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suspected. Phase II sampling is scheduled for individual
yards this summer. Phase II results will be used to
determine if any removal action is needed in those
residential areas. Results of the two sampling efforts
wtll be presented to the public in a data summary report
by late winter.
A residential preliminary risk assessment and ARARs
analysis will be completed by Spring 1991. Identifica-
tion of removal alternatives and drafting of the EE/CA
report will be conducted dunng the spring of 1991, with
release and public comment to occur dunng the summer
of 1991. The final decision for any removal actions will
be made summer 1991.
Projected Activities
•	Data summary report. Winter 1990
•	Preliminary risk assessment. Spring 1990
•	ARARs analysis, Spring 1990
•	Draft EE/CA report and public comment penod,
Spring 1991
•	Final EE/CA report and EPA decision docu-
ment, Summer 1991
•	Cleanup actions, 1991-92
ARBITER/BERYLLIUM REMOVAL
OPERABLE UNITS
Current Activities
An amendment to the Old Works EE/CA Adminis-
trative Order on Consent was signed in March 1990 to
conduct an accelerated removal project on the arbiter
plant disposal ponds and two beryllium disposal areas.
Minimal sampling is expected for this spring and the EE/
CA report is anticipated for completion this summer.
The removal action is expected to be conducted during
the 1991 field season. This removal action will not
address the entire Arbiter Plant operable unit at this
time.
Projected Activities
•	Field sampling. Spring 1990
•	Draft EE/CA report and public comment period.
Summer 1990
•	Final EE/CA report and EPA decision docu-
ment, Fall 1990
•	Cleanup action, 1991 field season
WASTE REPOSITORY SITING ANALYSIS
Current Activities
An amendment to the Anaconda Smelter Rl/FS
Administrative Order on Consent was signed in March
1990 to site a waste repository on the Anaconda S melter
site. Preliminary screening of the site is nearly complete
and EPA and ARCO will analyze and identify potential
repository locations by July 1990. The draft siang report
and public comment period is scheduled for late July
1990. Construction of a waste repository will be pan of
a clean up action for other operable units.
Projected Activities
•	Phase I screening report. May 1990
•	Phase II siting report, July 1990
•	Public comment period, July 1990
•	Final siting analysis, August 1990
REGIONAL GROUND WATER
SCREENING STUDY
A regional ground water screening study is being
developed to evaluate the potential for ground water
contamination from contaminant sources such as the
Opportunity Ponds, slag piles, red sands, tailings, Old
Works area and regional contaminated soils. Due to the
complex ground water system in the area several years
of ground water data may be required to conduct a full
investigation. EPA expects ARCO to begin data col-
lection activities this fall and to take several years. EPA
will use this data to conduct future investigations on the
entire site.
COMMUNITY/REGIONAL SOILS
SCREENING
With investigations nearly complete for Teresa Ann
Terrace, Cedar Park Homes and Benny Goodman Park,
a screening study is planned to evaluate the potential for
soil contamination in residential areas surrounding the
smelter as well as in outlying areas. Previous investi-
gations and screening studies indicate that soil con-
tamination due to past stack emissions is widespread.
This work is expected to begin later this year.
RECLAMATION STUDIES
Plans are underway to initiate a reclamation study to
identify possible remedies for contaminated soils. Po-
tential remedies for the smelter site may include chemi-
cally modifying and then revegetating selected areas. To
evaluate cleanup technologies, laboratory and field
studies may be required. These studies may take several
years to generate the appropriate types of data needed to
choose specific cleanup alternatives. Reclamation stud-
ies may be initiated on the site as early as this year.

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Anaconda Smelter
Mining Waste NPL Site Summary Report
Reference 5
Excerpts From Mill Creek Remedial Investigation/Feasibility Study,
Final Remedial Investigation Report, Mill Creek, Montana,
Anaconda Smelter Superfund Site, First Operable Unit;
Prepared for EPA by Anaconda Minerals Corporation;
September 1987

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MILL CREEK RI/FS
FINAL REMEDIAL INVESTIGATION
REPORT, MILL CREEK, MONTANA,
ANACONDA SMELTER SUPERFUND SITE,
FIRST OPERABLE UNIT

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ination. On site smelter wastes include about 185 million yd3 of tailings.
27 million yd3 of furnace slags, and about 0.25 million yd3 of flue dust
(Anaconda Minerals Company 1983). Approximately 63,200 yd^ of flue dust has
been consolidated into the flue dust storage facility located on the
hillside west of Hill Creek (Figure 8).
Information on the metals content of the various waste sources and
soils is summarized in Table 4. Flue dust contains the highest concen-
trations of arsenic, cadmium, copper, and lead. The arsenic concentration
in the flue dust ranges from 59,900 to 69,600 ppm, up to three orders of
magnitude greater than concentrations reported in the other waste media.
Particle size analyses conducted on the flue dust material show that over
40 percent of the flue dust has an effective particle diameter of less than
10 um (Tetra Tech 1985h). Because of its silt-Hlce texture, flue dust when
disturbed 1s readily eroded even by moderate winds.
Available air quality data from the M111 Creek monitoring station
indicate that contaminated materials are being re-entra1ned and transported
by winds. Airborne particulate metals concentrations for the 1984 to 1986
(Anaconda Minerals Company 1984b, 1985, 1986) sampling period are summarized
below:

As
Cd
Pb

(PP«n)
(PP«)
(ppm)
Average
1,500
160
1,500
Minimus
71
5
214
Maximua
25,941
1,667
10,588
These concentrations are within the range reported for contaminant source
materials (Table 4). The air samples were collected after the smelter was
closed; that Indicates that windblown dust Is a continuing source of metals
contamination. Recent air quality data collected through February 1987 are
similar to the data for 1984-1986 (see Appendix 0, Attachment 2). For
further discussion of airborne contamination, see the air investigation
section.
25

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Anaconda Smelter
Mining Waste NPL Site Summary Report
Reference 6
Excerpts From Endangerment Assessment for the Anaconda Smelter Site,
Final Draft for the Flue Dust Operable Unit; Life Systems, Inc.;
December 20, 1989

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Submitted ce:
Fluor Daniel, Inc.
18333 Preaton Road
Suit* 200
Dallaa, TX 75252
Accenclon: Mark deLorlaler-(1 copy)
Mike Glaze (1 copy)
TR-1165-26
ENDANGERMENT ASSESSMENT FOR
THE ANACONDA SMELTER SITE
Final Drafe for ehe Flue Dust
Operable Unit
Prepared Under
Prograa No. 1341
for
Subcontract No. 619800-9-K003
Under
Contract No. 68-W9-0013
for
ICA1R Work Assignment No. 041541
EPA Work Aaalgnaent No. 02-8P18
Contact: Mr. Gregory E. Scblefer
Telephone: (216) 464-3291
Deceaber 20, 1989

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EXECUTIVE SUMMARY
The Anaconda Smelter Is located about 25 miles northwest of Butte, Montana.
The facility began operation in 1884, producing primarily copper metal by
smelting ores brought in from mines near Butte. The Smelter was operated
until 1980, when it was closed. All of the on-site facilities except the
stack on Smelter Hill have since been demolished.
Activities associated with the operations of the Smelter resulted in substan-
tial contamination of the environment with a number of metals. Because of
this contamination and the associated potential risk to human health, the
Anaconda Smelter was placed on the National Priorities List. Site evaluation
and clean-up activities are being pursued by the U.S. Environmental Protection
Agency under authority granted by the Comprehensive Environmental Response,
Compensation and Liability Aet (CERCLA), as amended by the Superfund
Amendments and Reauthorleatlon Act of 1986 (SARA).
Although the Smelter is elosed, flue dust stored at several locations on the
property continues to be a source of environmental contamination. Flue dust
is a fine-grained waste material formed In the Smelter flue. Flue dust
cor.tains high concentrations of arsanlc, cadmium, copper, lead and other
metals. The amount of flue dust currently stored on site Is estimated to
exceed 316,000 tons.
Flue dust may lead to environmental contamination la a variety of ways. One
Important pathway la wind erosion of the flue dust, followed by dispersion of
thuse particles la sir to surrounding areas. The flue dust then settles,
le.idlng to a gradual accumulation in the soil. Flue dust may alao contaminate
th) hypothetical future on-site residents. These populations are likely to be
eiiposed to fluo dust mainly through breathing flue duat particles suspended in
aJ.r or by Incidental ingestion of soil contaminated with flue dust. Current
rualdents and on-site visitors are not likely to be exposed to flue dust
contaminants vie drinking water, but this Is of likely concern to future
on-site residents drawing water from beneath the site.
Estimation of the exposure of these populations to flue dust Is compllcsted by
t'ae fact that direct measurement (aonltorlng) of th« concentration of various
metallic components of flue dust In environmental media (air, soil, water)
cannot distinguish the levels of contaminants contributed by flue dust from
those contributed by other sources. For hypothetical future on-site residents,
this is of little concern, since the relative contribution of other sources is
ES-1

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likely co b« small la the immediate vicinity of the flue dust piles themselves^
However, for off-slCe exposures, the relative contribution of flue duat to
total envlronaental contamination can only be estimated uaing mathematical
models. Calculations using available data and simple models Indicate that the
results of such modeling efforts are not likely to be sufficiently accurate to
justify use of the values to estimate flue-dust specific exposures or risks.
For this reason, estimates of exposure and risk to off-site residents have
been performed using only the total level of contaminants measured in air and
soil; these values should not be confused vith estimates of exposure and risk
due specifically to flue dusc.
This analysis yields the following main conclusions:
• An imminent and substantial endangerment would exlse for hypothetical
future on-site residents. Of chief concern would bs a high risk of
lung cancer (1 In 100 to 7 in 100) resulting from inhalation of
arsenic in air, with a smaller, but still significant risk of lung
cancer (1 in 10,000 to 4 in 10,000) contributed by cadalua in air.
Also of concern would be a high risk of skin cancer (4 In 100 to 3 in
10) due to Ingestion of arsenic. Future on-site residents (especially
children) would also be subject to high risks of noncarclnogenic
effects from lead and arsenic In air and soil.
e Occasional visitors to the site (dirt-bike riders) are likely to
experience only a small increase In risk of lung cancer (3 In 100,000)
or skin cancer (5 In 100,000), but these risks could become
significant (4 in 1,000 to 1 in 10) if visits war* frequent and
extended. Similarly, occasional site visitors have no significant
risk of noneancar health effects unless site visitation is frequent
and extended.
e Total lifetime lung cancer risks to current residents of East Anaconda
appear to be on the order of 2 in 100,000. This Is due mainly to
arsenic In air vleh lower risk levels due to cadmium in air. Skin
cancer risks from Ingestion of arsenic in soil are probably around 1
in 10,000 Co 4 In 10,000, but the fraction of this risk that Is due
specifically to flue dust is not known.
It is concluded that the flue dust piles currently on site pose a significant
health risk to hypothetical future residents of the site, and may also be
contributing co health risks for current site visitors or nearby residents.
Risks to plane and animal species on and around the site cannot be evaluated
quantitatively with current data, but analysis of information on apecles
likely to be present and pathways of flue dust migration suggest the
following:
e Aquatic species In Van Springs Creek or Mill Creek are not likely to
be affected under current conditions, sines runoff from the site Is
controlled and does not reaeh these waters. Under tha no-action
ES-2

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(8&Z) of the 12,518 residents of Deer Lodge County reside within the city
limits of Anaconda, approximately 1.5 miles west of Smelter Hill (Figure 1-2).
The xemainder reside within Warm Springs, Opportunity and surrounding rural
area:. (Tetra Tech 1985a,b).
Two residential populations have been selected as those most likely to come
into contact with the contaminated media identified in Section 5.1. They are
the closest current residents to the site (residents located in East Anaconda)
and hypothetical residents who may reside on the site some time in the future.
Both child and adult residents will be evaluated. Opportunity is located in a
downwind direction from the Smelter, but its residents were not chosen for
evaluation for two reasons. First, an air monitoring station is not located •
in Opportunity, so there are no measurements of the concentration of metals in
the .unbient air. Second, the prevailing southwesterly winds (as illustrated
in FLgure 5-2) tend to divert airborne particulates away from Opportunity,
making it very difficult to model transport into this area.
Site Visitors (Dirt Bike Riders)
Sine: access to the site is only partially restricted, it is likely that
Individuals may enter it and come into contact with contaminated soil or the
flue dust. The concentrations of metals are higher in on-site media than in
residential areas, so individuals who access the site could be exposed to high
concentrations of metals. These Individuals could Include site maintenance
personnel, hunters, hikers, dirt-bike riders, rock and mineral collectors and
tourists. Of these individuals, dlrt-blke riders are assumed to be subject to
the highest level of exposure because of the nature of the sport. High-speed,
wheeled vehicles traversing the storage piles can raise large volumes of dust
and dirt. The suspended particles may then be inhaled or Ingested by the
riders.
5.2.2 Pathways of Exposure
Based on the distribution of chemicals in the environment and likely human
contact with environmental media, a number of exposure pathways were
idertlfled as being likely or plausible. These pathways are described below.
5.2.2.1 Inhalation
Since flue dust can be transported easily by the wind, inhalation of the
partlculates dispersed and transported from the storage areas la an Important
exposure pathway. Particle size analyses conducted on the flue dust indicate
thai: approximately 61Z of the material has an effective particle diameter of
10 no or less (Tetra Tech 1985a). Particles less than 10 ym generally settle
or .impinge on the walls of the trache^ and lungs. Particulate matter 2 to
10 um in diameter is largely removed from the lungs by ciliary action to the
throat where it is swallowed. Particles less than 2 um are deposited deeper
in i:he lungs where residence is measured in weeks, months or years (Sterns et
al. 1973).
5-7

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Soils contaminated with flue dust may become airborne (reentrained) through
wind erosion and contribute to the total exposure through inhalation. The
concentration of flue dust in the air that is derived from contaminated soils
is assumed to be proportional to the concentration of flue dust in the soil.
5.2.2.2	Ingestion of Soils
Humans may ingest flue dust by inadvertently ingesting contaminated soils.
The use of the term "soil" generally refers to outdoor dirt and indoor
household dust combined. Ingestion occurs mainly through mouthing of soiled
objects by children (e.g., toys, hands), eating from utensils on which dust
has settled and through habitual hand-to-mouth actions (e.g., smoking, biting
fingernails).
There are many studies in the literature investigating the amount of soil
ingested (Binder et al. 1986; Calabrese et al. 1987, 1989; Havley 1985;
Kimbrough et al. 1984; LaGoy 1987; Duggao and Williams 1977). It is generally
agreed that the amount of soil Ingested is highest in children and decreases
as the child grows older and enters adulthood. The USEPA (1989a) has
estimated that typical soil ingestion ranges from 200 to 800 mg/day for a
child, and from 100 to 200 mg/day for an adult.
5.2.2.3	Ingestion of Groundwater
Ingestion of drinking water obtained fron local groundwater is a pathway by
which Individuals may be exposed to contaminants released from the site. The
primary regional source of water for domestic and irrigation use is
groundwater obtained from the unconsolidated valley alluvium. Groundwater
elevation contours for this aquifer indicate that regional flow is to the
northeast (Konlzeski et al. 1962). The municipal water supply for the City of
Anaconda is drawn from three wells west of the city (SW 1/4 Sec. 33, T5N,
R11W) and completed in the alluvial aquifer. /Tills source serves approximately
10,000 of the 12,518 residents of the county. The remaining residents are
served either by private groundwater wells or by other unspecified sources
(Clement 1987; Tetra Tech 1986). Because the city wells are basically upwind
of the flue dust piles, it Is unlikely that groundwater at the well locations
could be significantly contaminated by leaching from flue dust transported to
the area through air. Because the veils are also up-gradlent from the flue
dust piles themselvesi it is unlikely that significant contamination has
reached these wells via direct leaching and transfer through soil or
groundwater. Therefore, groundwater is not considered to be a significant
source of exposure to flue dust contaminants for current off-site residents of
Anaconda.
Groundwater directly beneath the site is heavily contaminated with metals
(Tetra Tech 1985b), and it Is likely that leaching from flue dust has
contributed to this contamination. Therefore, Ingestion of groundwater is
(a) Personal communication with Mr. Harvey Ravendal, Anaconda Water Depart-
ment, Anaconda, Montana. November 10, 1988.
5-8

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Anaconda Smelter
Mining Waste NPL Site Summary Report
Reference 7
Excerpts From Site History of Smelter Hill - Anaconda Smelter NPL Site;
Prepared for ARCO Coal Company by GCM Services, Inc.;
June 1989

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034-0423
• ©I • 0}. 00/0387
SITE HISTORY OF SMELTER HILL - ANACONDA SMELTER NPL SHE
far
ARCO Coal Company
555 Seventeenth Saeet
Denver, CO 80202
June 1989
GCM SERVICES INC.
P.O. Box 3047
1003 3. Montana
Butte, Montana 59702
(406) 723-4387

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THE ORIGINS AND EVOLUTION OF MONTANA METALLURGY
2
Butte Copper Mining and Metallurgy
The mining and smelting of copper in Butte, Montana emerged as a viable industry only as the
demand for the metal increased dramatically during the 1880s with the expanding use of electricity
and with the increased capital investment on the Montana frontier in the technologies necessary to
transform vast ore reserves into a usable metal. Prior to the 1880s, the mines of Michigan's
Keweenaw Peninsula dominated the world copper market, but the exploitation of massive sulphide
copper reserves at Butte by mine entrepreneurs Marcus Daly and William A. Clark quickly changed
challenged Michigan's predominance. Initially, frontier Montana lacked facilities for processing
complex copper ores and Daly was forced tp separate out his richest ores and ship them to Swansea,
Wales for smelting. In 1879 William A. Clark applied lessons learned in Colorado to the design of
the Colorado & Montana smelter, built south of Silver Bow Creek. In 1880 Charles T. Meader,
working for the Lewisohn brothers, erected the Montana Copper Company smelter east of Butte in
an area tliat became known as Meaderville. In ^881 the Parrot Silver and Copper Company erected
a smelter that produced a high quality silver-copper mane. The installation of converters at the Parrot
smelter in 1884 marked a new era in American copper metallurgy, making it the first American plant
to successfully use the Bessemer process for treating copper matte. Within a short time Bune
processed ore at six local smelters: the Montana Copper Company, die Parrot, the Colusa, the Butte
Reductio n Works, the Butte & Boston, and the Colorado & Montana. The Butte smelters were
hampered by a small daily production capacity, high labor costs and environmental problems created
by smokestacks and open roasting pits belching sulphurous fumes. At the same time, Butte copper
production continued to expand exponentially, creating a for larger and more efficient
smelting ifacilities (Malone 1981; Quivik 1984).
The Birth of Anaconda Smelting; The Old Works
By 1883 Itfarcus Daly's men began encountering a vein of copper SO to 100 feet wide in his
Anacondii mine, ranging in purity from 12 to 45 percent copper. A shortage of efficient smelter
capacity forced Daly to seek access to capital for his own smelting facility. Daly sought the
financial assistance of San Francisco capitalists, Hearst, Tevis and Haggin, and with their support
located a :anelter site 26 miles west of Butte with ample water from Warm Springs Creek. During
the summer of 1883, under the supervision of William McCaskell, an associate of Haggin's, Daly
initiated construction of the nation's largest concentrator and a 450-ton a day smelter known as the
Upper Works. The Upper Works included the concentrator, smelter buildings housing roasters
and revertxrauxy furnaces, all connected to long masonry flues and two smokestacks measuring
115 and 175 ft respectively. With the firing of the Upper Works smelter in 1884 Daly's new town
of Anacoitda grew rapidly. In 1886 Daly hired smelterman. Otto Stahlmann, to expand daily
capacity to 1000 tons and to replace hand roasters with Bruckner furnaces, 9 ft in diameter by 18 ft
tall brick-lined steel furnace. Although the copper mane produced here still had to be shipped east
for refining, the facilities represented a vast improvement over the technologies developed by the
Welsh ovtr the centuries at Swansea (Malone 1981; Quivik 1984).
Additional ore production from Daly's growing portfolio of Butte mines and the technological
limitations of the Upper Worics plant, prompted Daly to plan and begin building additional smelter
capacity, one mile east along Warm Springs Creek, at the Lower Works in 1887. In 1889 fire
destroyed :Jxe Lower Works. Undaunted by the disaster. Daly immediately ordered rebuilding with
steel and tlie Lower Works commenced processing 3000 tons of ore daily in October 1889. That
same year Daly erected a new set of converters at the Upper Works and completed an electrolytic
copper refinery between the Upper and Lower Works. Along with the new smelter and refinery
Daly constructed the town of Carroll for Lower Works employees in 1887. By 1890 Daly had a
new converter system installed at the Lower Works and enlarged the electrolytic refinery's capacity.

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3
increasing daily production of99.97 percent pure copper to 120 tons, putting Daly and the
Anaconda Mining Company on eaual footing with Michigan copper producers. Additional
improvements were made to the Upper Works in 1894. Daly arranged to have the reverberatory
furnaces enlarged, increasing daily production and efficiency. By increasing die length of the
reverberatories Daly's engineers doubled daily output while maintaining the same fuel consumption.
The Lower Works used three masonry flues and smokestacks the size of those at the Upper Works.
Yearly production at the Upper and Lower Works <130 million lbs) far outdistanced all the
competition in Butte and Great Falls (Boston & Montana, 54 million lbs) by 1901 but Daly's
acquisition of other highly productive Butte mines prompted the need for father expansion at
Anaconda. Daly's chief problem in his location north of Warm Springs Creek was space for
expansion which he solved in 1902 by moving operations south across the valley. Demolition of
the Old Works (Upper and Lower) began in 1903, shortly after the startup of the Washoe Reduction
Works, with the removal of all equipment, wood and steel, leaving only stone and brick ruins after
1906. (Quivik 1984).
Creation of a Mining and Metallurgical Empire: The Anaconda Copper Mining Co.
By the late 1890s Marcus Daly's consolidation of mining interests in Butte led to a shortage of
smelter capacity in Anaconda. In addition, Daly's vision for the future had outstripped his personal
financial means. Daly's dilemma attracted the attention of William Rockefeller and Henry H.
Rogers of Standard Oil and in 1899 they formed the Amalgamated Copper Company, which
absorbed Daly's Anaconda Copper Mining Company. Daly traded his controlling shares in the
Anaconda Copper Mining Company for shares in the new copper trust, and as president of
Amalgamated, Daly had the assets needed to build the reduction works of his dreams as well as to
create America's first fully integrated copper company, with control of all aspects of production
from mine to smelter to refinery to fabrication. Daly hired Frank Klepetko, designer of the state-of-
the-art Boston & Montana smelter and refinery in Great Falls, to build one of the most efficient and
adaptable mineral processing plants in the world. Hie Washoe Reduction Works began operating in
1902, two years after Daly's death, at a capacity of 4800 tons daily. Klepetko designed the Washoe
smelter so that each department could grow and expand with demand: by 1908 production capacity
grew to 12,000 tons of ore daily, producing 600,000 lbs of copper and 9000 tons of slag and
tailings and by 1933 the Washoe smelter produced 1,000,000 lbs daily. The legacy of Daly's
vision did not end with construction of the wold's largest non-ferrous mineral processing plant.
Daly's successor, John D. Ryan, continued to add to this ACM Co. portfolio by acquiring additional
smelting capacity in Great Falls, Montana; Tooele, Utah; mining operations in Arizona and Chile;
expanded refining capacity in Great Falls and New Jersey and the purchase of a fabricator in the
American Brass Company. Facilities at the Washoe Works expanded into more complete use of the
Butte ere with the addition of zinc and	plants. ACM Co. interests also included coal,
timber and an ore-hauling railroad, the Butte, Anaconda & Pacific. By the end of World War I the
ACM Co. represented the most powerful economic and political force in Montana and one of the
world's largest producers of base metals (ACM Co. Collection, Tri-County Historical Society,
Boxes 8; 59; 60).
HISTORICAL DEVELOPMENT OF THE WASHOE REDUCTION WORKS
When completed in 1902 the Washoe Reduction Works constituted an industrial processing slant
of extraordinary magnitude, covering over 230 acres with a monthly copper production of 12
million lbs. Expanding to meet the demand created by increasing Butte mines production, the
Washoe eventually expanded to 25 million lbs monthly with a workforce of 2800. To meet the
17,000 too per day production capacity the Washoe consumed 750 tons of Diamondville,
Wyoming bituminous coal (12-15 percent ash), 2500 tons of lime (for flux), 778,000 kilowatt
hours of electricity and 60 million gallons of water (75 percent reclaimed in process) transported
through eight miles of wooden flume. The following is a detailed description of the on-site

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4
activiies that occurred at the Washoe Reduction Works and die processes involved in producing
vast quantities of copper, zinc, manganese, phosphate fertilizer, sulphuric acid and fire bricks.
Concentrator
The Facility and the Process
At the tipper end of the Washoe Works stood 21 ore bins; a six-story 40 x 60 ft, wooden sampling
mill; a concentrator power house (which also supplied power to die town of Anaconda initially); and
two sted and wood buildings measuring 255 x 350 ft that house the concentrator. The concentrator,
divided into east and west mills, contained four separate mills on each side. There was also a 70 x
670 ft woodframe building to house nine settling tanks.
The process of concentrating the copper ore for smelting began with crushing. Approximately 125
cars filled with Butte ore arrived daily in the sorting yards in east Anaconda where 27-car trains
were asssmbled for the 7.5 mile climb to the top of the smelting complex. The ore was divided
into two groups: the 1st class ore (6 percent copper) weighed and sent directly to the blast furnace
and 2nd class (4 percent) sent to concentrator. The ore was dumped from the cars by a tipple into a
hopper that emptied the ore onto conveyors leading to the ore-cnishing plant. A three-story
building housed a gyratory crusher, used to accomplish the initial ore crushing and moved from
there to a secondary cone crusher and on to a series of fine roll crushers and screens. During the
first stage of the concentrating process the ore entered Hardin ge mills where steel balls further
pulverized the ore. The concentration process at the Washoe Works initially used gravity and a
variety of agitating tables to separate waste rock from the copper minerals. A series of changes in
the concentrating process beanning in about 1912 increased copper recovery at the Washoe Works
from 83 to 96 percent (ACM Co. Collection, Tri-County Historical Society, Box 8 1946).
Plant Additions and Improvement*
For decade, t mills had been plagued by the problem of recovering valuable copper minerals from the
slimes (fine sands) lost in the crushing. Up until 1913 the Washoe Works sent 2200 tons of slime a
day, containing 22 percent copper, to the slime ponds as waste. In 1912 ACM built an
experiment 1 round table separator, when combined with thickeners and filters, recovered an
additional 1:5 million pounds of copper yearly from Anaconda slimes. The principle of the round
table actually can be traced to die ancient process of buddling with origins in Cornwall in the
thirteenth ceatury. The buddle, as described in Agricola's Dc Re Metaiica published in 1556, was a
rectangular v/ooden trough which used gravity and water to wash away the lighter waste rock from
the heavier minerals. The Cornish used a round buddle, a series of radial box buddies, for dressing
tin. In 1853 ihe Germans operated the first rotary round table at a mill in the Harz Mountains. Two
decades later an engineer named Evans created a double-decked slime table in the Lake Superior
District. In 1382 the Evans Slime Table appeared in Butte at the Colorado Smelting & Mining
Company but shortly thereafter was abandoned for the Frue vanner, a vibrating table used
extensively in gold and silver mining districts. ACM Company initially began experimenting with
revolving round tables at the Boston & Montana smelter in Great Falls in 1905. JJVL Callow of
Salt Lake set up a system using Callow settling tanks. Engineers at the Washoe Works, led by C.
O. Demond, modified the Callow system to meet their concentrating needs, installing a 20-deck
round table ami a series of dewatering devices including a Kuchs-Laist centrifugal separator.
Callow tanks, <3ancd filters and Dorr continuous thickeners. The dewatering and concentrating
process at the new round table plant moved 2500 tons of slimes a day through the Dorr thickener, a
circular woodei tank measuring 3 ft deep and 28 ft wide, and through the 20-deck round table, into
a series of Don y*i«wg tanks and on through the Oliver filters. The ACM Company ranked the
new round tabic plant as a major technological and economic success citing the plant's low
maintenance, small size, simplicity of design, its low operating costs (12* a ton), and its
extraordinary recovery rate (moving ACM from 75 to 95 percent copper recovery). ACM recovered

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Mining Waste NPL Site Summary Report
Atlas Asbestos Mine Site
Fresno County, California
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-0025, Work Assignment Number 20.
A previous draft of this report was reviewed by Dan Meer of EPA
Region IX [(415) 744-2219], the Remedial Project Manager for the
site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
ATLAS ASBESTOS MINE SITE
FRESNO COUNTY, CALIFORNIA
INTRODUCTION
The Site Summary Report for the Atlas Asbestos Mine is one of a series of reports on mining sites on
the National Priorities List (NPL). The reports have been prepared to support EPA's mining program
activities. In general these reports summarize types of environmental damages and associated mining
waste management practices at sites on or proposed for the NPL as of February II, 1991 (56 Federal
Register 5598). This summary report is based on information obtained from EPA files and reports
and on a review of the summary by the EPA Region IX Remedial Project Manager for the site, Dan
Meer.
SITE OVERVIEW
The Atlas Asbestos Mine Superfund Site is an abandoned asbestos mine and mill site located on 435
acres approximately 18 miles northwest of Coalinga, California. The property is owned by the U.S.
Bureau of Land Management (BLM). Ten acres of property directly under the mill building is
privately owned (Reference 2, page 1-3) The Atlas site lies within the New Idria serpentinite mass,
a 480-square mile formation of serpentine which contains naturally occurring chrysotile (Reference 4,
page 1). Chrysotile fibers have an elongated, needle-like structure and have been widely used for
their high tensile strength and flexibility and their noncombustible, nonconducting, chemically
resistert properties (Reference 1, page 1-12). The Atlas site ranges in elevation from 4,000 to 4,400
feet. Major features of the site include three open pit mines; stockpiles of asbestos waste material
(excavated ore and mill tailings) within the mines; abandoned mill facilities; and an area of stockpiled
asbestos waste material in the immediate vicinity of the mill facilities (Reference 2, page 1-3).
The Atlas Asbestos Mine site and the Coalinga Asbestos Mine site were jointly proposed for the NPL
in 1982 and listed in 1984 (Reference 4, page 3). The Coalinga Asbestos Mine is of concern because
both it and the Atlas site are possible sources of asbestos contamination in the California Aqueduct
and the Towns of Coalinga and Huron. Remedial Investigation/Feasibility Study reports were
released in March 1990. A Record of Decision (ROD) documenting the selected remedy at the Atlas
mine site was issued on February 14, 1991. EPA's preferred remedial action, as discussed in the
ROD, includes restricting access to the site by preventing off-road vehicle use of the mine site and
diverting surface waters around contaminated soils The total present worth cost to implement this
remedi;d action is $4.2 million (Reference 4, page 24)
1

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Atlas Asbestos Mine Site
OPERATING HISTORY
Primary asbestos mining operations in the New Idria serpentinite mass began in 1959. The Atlas
Minerals Division of Atlas Corporation acquired title to a large block of claims and began mill
construction at the Atlas site in 1962. Mining and milling of chrysotile asbestos fibers occurred from
1967 to 1979. From 1967 to 1974, the facility was owned by the Vinnell Mining and Minerals
Corporation. In 1974, the facilities were sold to Wheeler Properties. Wheeler Properties continued
operations until 1979, then filed for bankruptcy shortly thereafter. The property is currently owned
by the United States (U.S.) government and administered by BLM. Ten acres of land directly under
the mill building has reverted to the State of California for Wheeler Property's inability to pay
delinquent property taxes (Reference 2, page 1-8). The Remedial Investigation/Feasibility Study
report did not contain information on the mining operations that created the problem.
SITE CHARACTERIZATION
The Atlas Asbestos Mine site is located on approximately 435 acres of Federally owned land, 18
miles northwest of the City of Coalinga, California. The site lies south of the San Joaquin Ridge in
Sections 31 and 32, Township 18 South, Range 13 East, on the U.S. Geological Survey (USGS)
Santa Rita Peak Quadrangle (Reference 2, page 1-3). Figure 1 locates the site in California and
Figure 2 locates the site within the Los Gatos Creek Watershed. Figure 3 indicates the location of the
mine, storage pits, stockpile area, and mill facility for the Atlas Asbestos Company site.
The terrain in the vicinity of the site is rugged Hill slopes range from 5 percent to 65 percent and
have an average slope of 10 percent to 15 percent. The vegetation at higher levels is primarily of
mixed chaparral and yellow pine. At lower elevations, the land is vegetated with oak forests. In
many areas, soil disturbances and hill erosion has prevented the reestablishment of vegetative
communities (Reference 2, page 1-2).
In March 1990, EPA finalized a Remedial Investigation that documented the environmental
characteristics, and the type and extent of contamination at the site. EPA found that stockpiled
asbestos tailings, asbestos-rich natural serpentine soils, and natural sedimentary soils were the sources
of contamination. Asbestos is entrained in air currents and surface water and deposited in soils and
sediments. Therefore, air and surface water are the exposure pathways of interest. The contaminant
of concern in these media is chrysotile asbestos. Although mercury, chromium, and zinc are present
in soils, they are not present in concentrations above levels of concern (Reference 2, pages 4-65 and
7-1).
2

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Mining Waste NPL Site Summary Report
Htm lon«
3«ro«nttnita U«««
ATUU SITE
CCAL1NGA SITE
36° 1S'N W
120° 30"W ;
to "lilB
FIGURE 1. PROJECT VICINITY MAP
3

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Atlas Asbestos Mine Site
ATLAS SITE
LEMOORE
NAVAL
AIR STATION
COALINGA SITE

S
S
LEGENO
AUmiioi - Itiih
&IIVWAIMM SO.t
ARROYO PASAJERO
DRAINAGE BASIN
BOUNOAHY
FIGURE 2. ARROYO PASAJERO DRAINAGE BASIN
4

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Mining Waste NPL Site Summary Report
UPPER MINE I
t MILL FACILITY
S >» ANO T -. '
MAIN STOCKPILE
r. 1 AREA^r£_,. *.
cruz pit
HANSEN RESIDENCE
0	2000	400Q fMt
1	*	1	' 	•
FIGURE 3. GENERAL SITE MAP
i
5

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Atlas Asbestos Mine Site
Air
Continuous meteorological monitoring began in September 1985 and continued for 2 years at the
Atlas mine site (Reference 2, page 3-3). Average daytime wind directions at the Atlas site are from
the southeast and southwest. Local topography channels south winds to a south-southwest or
southwest direction The occurrence of high winds speeds from only a narrow range of directions
strongly influences the transport patterns of materials entrained by wind erosion (Reference 2,
page 3-10). The nighttime drainage winds at the Atlas site are extremely weak as the site is near the
point of flow origin (Reference 2, page 3-21).
Meteorological parameters (including temperature, wind speed and direction, precipitation, and
relative humidity) were continuously monitored for 2 years beginning in 1985 (Reference 2, page
3-3). Regional air monitoring was conducted at 25 locations in the area of the Atlas Asbestos and
Coalinga NPL sites during the summer of 1986, the winter of 1987, and the summer of 1987 Air
monitoring stations were located upwind and downwind of the Atlas Mine as well as other locations
in the Coalinga area (Reference 4, page 7). Airborne asbestos concentrations at the Atlas site were
determined only during the summer of 1987 collection period (Reference 2, page 4-57). During high
wind events [greater than 10 meters per second (m/s)] the asbestos emissions rates from the Atlas
tailings pile and mine are high. The frequency of high winds are low, and none occurred during the
sample phase. For this reason, it is unlikely that wind erosion from the waste piles occurred during
the sample period (Reference 2, page 4-56). During periods of low wind speed, asbestos emissions
are primarily from vehicle travel over unpaved roads and on the waste piles (Reference 2, page 7-4).
The results of air sampling analyses indicated that the asbestos concentrations at all sampling stations
were higher than generally accepted background levels [about 100 fibers per cubic meter (fibers/m3)].
Air sampling stations in the immediate vicinity of the Atlas mine site were located upslope and
downslope of the mine site and at the Hansen residence, immediately outside the mine site. The
mean daytime asbestos concentration levels for the sampling stations upslope and downslope of the
Atlas site and at the Hansen residence were 3,690, 17,605, and 46,058 fibers/m3, respectively.
Nighttime concentrations were significantly lower at all stations. The mean nighttime asbestos
concentration levels for the sampling stations upslope and downslope of the Atlas site and at the
Hansen residence were 1,981, 3,705, and 16,085 fibers/m3, respectively (Reference 2, page 4-57).
Surface Water
Most of the precipitation occurs in the form of rain, though snowfall is possible. Summer
precipitation is generally limited to occasional isolated showers associated with thunderstorms.
6

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Mining Waste NPL Site Summary Report
Overall, storm activity brings measurable precipitation to the region on only 40 days a year. The
mean ainual precipitation is less than 15 inches. Approximately 90 percent of this amount falls
between November and April (Reference 2, page 3-1). Measurable surface-water flows in Los Gatos
Creek occur generally in the winter and spring. During the summer and fall months, gauged flows
are extiemely low or nonexistent (Reference 2, page 3-21).
Asbestos concentrations in the surface water near the Atlas mine site exceed both the ambient water-
quality criterion for the protection of human health and the proposed maximum contaminant goal
None of the surface-water areas sampled during the Remedial Investigation are being used or are
plannee for use as drinking sources (Reference 2, page 6-98). Three sampling stations along streams
draining both the New Idria serpentinite mass and the Atlas site contained concentrations of total
asbesto; ranging from 2.5 x 107 to 6.6 x 107 Million Fibers Per Liter (MFL). In the immediate
vicinity of the Atlas site, measured asbestos concentrations in streams ranged from 2 7 x 10^ to 3.1 x
108 MFL. The highest total asbestos concentrations were measured upstream of the Atlas site. The
site of ihe highest asbestos concentrations receives runoff from the New Idria serpentine mass, roads,
and other mine sites (Reference 2, page 4-17). Surface-water modeling showed that during heavy
rains, between 5 and 36 percent of the total asbestos yield in the Las Gatos watershed can be
attributed to Atlas Mine (Reference 4, pages 6 and 7).
Asbestos fibers longer than 10 microns were found in only five surface-water samples, and all were
located on White Creek below the Atlas site. Where detected, the long fiber concentrations ranged
from 7 2 x 103 to 4.4 x 10s MFL The highest concentrations were found at the sampling stations
nearest the Atlas mine site (Reference 2, page 4-21).
Soils
Detailed analysis of soil samples in the vicinity of the Atlas Mine found large amounts of highly
concemxated asbestos. Soil samples tested by Polarized Light Microscopy (PLM) analyses found
asbestos concentrations to range from Not Detected (ND) to 4 area percent. Soil samples analyzed by
the Transmission Electron Microscopy (TEM) found asbestos levels to range from 3 to 100 percent
(Reference 4, page 6). The exact location and date the sampling was conducted was not included in
the ROD.
7

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Atlas Asbestos Mine Site
Sediments
Sediment samples were collected from streambeds and the sedimentary basin. Specifically, samples
were collected from the following areas:
•	Across each streambed above and below the confluence of major tributaries to Los Gatos
Creek, near population centers, and at a background location 5 miles upstream of Coalinga on
Warthan Creek
•	In the sedimentation basin between Interstate 5 and the California Aqueduct, in the area
surrounding the Town of Huron (Reference 2, page 2-26).
All samples collected in the vicinity of the Adas Mine had asbestos concentrations ranging from ND
to 6 percent asbestos. The highest concentration, 6 percent, was measured immediately below the
Atlas site. A sample collected from White Creek, which drains the New Idria formation, contained 2
percent asbestos by PLM analysis and 10 percent asbestos by TEM analysis, confirming that asbestos
is being transported out of the New Idria serpentinite mass. Background asbestos concentrations from
a sample site on Warthan Creek (near Coalinga) contained less than 1 percent asbestos by PLM
(Reference 2, page 4-25).
ENVIRONMENTAL DAMAGES AND RISKS
Initial interest in the site was created in 1980, when the California Department of Water Resources
found elevated levels of asbestos in water samples from the California Aqueduct (Reference 2,
Executive Summary, page 1). The Atlas and Johns-Manville Coalinga mine and mill sites were
identified as possible sources of asbestos contamination.
Population around the site is sparse, but there are several groups of persons who may potentially be
exposed to contamination. The surrounding area is used by hunters, hikers, campers, and recreational
off-road vehicle drivers. There are also 50 to 100 cattle ranchers and other individuals living
downslope of the site. The Hansen residence is the closest residence to the mine site. The nearest
town to the Atlas Asbestos mine site is Coalinga (with an estimated population of 7,800 in 1987)
(Reference 2, page 6-24).
The February 1991 ROD identified inhalation and ingestion of asbestos as two general routes of
exposure. Inhalation of asbestos is the exposure pathway of greatest concern because this pathway
has been positively linked to cancer in humans (Reference 4, page 8). Asbestos is known to cause
asbestosis, lung cancer, and mesothelioma. Associated with asbestos exposure are cancers of the
8

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Mining Waste NPL Site Summary Report
larynx, gastrointestinal tract, kidney, and ovary, and respiratory diseases such as pneumonia
(Reference 2, page 1-2).
The greatest health risk: posed by the Atlas Mine is correlated with activities, such as motorized
vehicles, that result in disturbances of asbestos-bearing surfaces Emissions of asbestos-contaminated
dust generated by off-road vehicles and agricultural tilling practices were estimated using equations
from EPA's 1985 "Compilation of Air Pollutant Emission Factors for Stationary Point and Area
Sources" (Reference 4, page 9).
In calculating the ambient air risk, it was assumed that a 20-year-old male will be present for 8 hours
a day, !>2 days a year, for 10 years, to yield a continuous exposure duration of 0.47 years (the
average case). For exposure to air during off-road vehicle activity, it was assumed that a 20-year-old
male drives for 3 hours a day, 16 days a year for 5 years (the average case) (Reference 4, page 9).
The est mated excess lifetime cancer risk for individuals hiking, camping, or hunting at or nearby the
Atlas Mine was calculated to be 1 x 10"* to 3 x 10"3 under average and maximum exposure conditions,
respectively. The estimated excess lifetime cancer risk for individuals driving off-road vehicles at the
Adas Mine was calculated to be 5 x 10"4 to 4 x 10"' under average and maximum exposure conditions,
respectively (Reference 4, page 10).
The estimated excess lifetime cancer risk from drinking water from the California Aqueduct that can
be attributed to the Atlas Mine was found not to be significant. Risks estimates were calculated
assume ingestion of 2 liters of water a day for a 70-year period by an adult weighing 70 kilograms
(Reference 4, page 10).
The estimated excess lifetime cancer risk from drinking untreated water from the California Aqueduct
(contaminated with asbestos from all sources in the Los Gatos Creek Drainage Basin) ranged from
2 x lfr6 to 4 x 10"3 under average and maximum exposure conditions, respectively. However, it
should be noted that municipalities are required to treat drinking water, under the Safe Drinking
Water Act, to reduce human exposure to asbestos (Reference 4, page 10).
REMEDIAL ACTIONS AND COSTS
In 1985, EPA initiated an Remedial Investigation/Feasibility Study at the Atlas site to determine the
nature End extent of asbestos contamination, possible threats to human health and the environment,
and the necessity for remedial action. In March 1990, EPA released the Remedial Investigation/
Feasibility Study Report for the Atlas mine site. In February 1991, EPA documented the remedial
9

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Atlas Asbestos Mine Site
action in the ROD. The remedial action includes the following drainage and stability improvement
activities:
•	Restricting access to the site by constructing fences and posting signs
•	Constructing surface-water diversion channels around contaminated soils
•	Constructing sediment-retention dams to reduce sediment transportation
•	Paving the road through the Atlas mine to reduce airborne asbestos emissions
•	Evaluating the ability of the native vegetation to be established on the disturbed areas without
importing large quantities of top soil
•	Filing deed restrictions
•	Monitoring the site for future asbestos levels (Reference 4, page iv).
The estimated capital cost for the above remedial action is $4.2 million (Reference 4, page iv). The
estimated time to implement this action is 4 months (Reference 3, page 6). The cost for monitoring
the site after completion of the remedial action was not estimated.
CURRENT STATUS
On February 14, 1991, EPA documented the selected remedy in a ROD for the Atlas Asbestos Mine
Area Operable Unit of the Atlas Asbestos Mine site. According to EPA, a Special Notice was sent to
the PRPs stating that the ROD was signed and remedial action would begin on March 29, 1991.
10

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Mining Waste NPL Site Summary Report
REFERENCES
1.	Fe,isibihty Study Report, Atlas Asbestos Company Site; EPA; March 1990
2.	Atlas Remedial Investigation Report and Phase I of Johns-Manville Coahnga Remedial
Im estigation Report, EPA Region IX, March 1990.
3.	Atlas Asbestos Company Superfund Site, Fact Sheet; EPA Region IX; April 1990.
4.	Rex>rd of Decision, Atlas Mine Area Operable Unit of the Atlas Asbestos Mine NPL Site; EPA
Region IX; February 14, 1991.
11

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Atlas Asbestos Mine Site
BIBLIOGRAPHY
U.S. Environmental Protection Agency. Feasibility Study Report, Atlas Asbestos Company Site
March 1990.
U.S. Environmental Protection Agency, Region IX.
Sheet. April 1990.
U.S. Environmental Protection Agency, Region IX.
Asbestos Mine NPL Site, Record of Decision.
Atlas Asbestos Company Superfund Site, Fact
Atlas Mine Area Operable Unit of the Atlas
February 14, 1991.
U.S. Environmental Protection Agency, Region IX. Atlas Remedial Investigation Report and Phase I
of Johns-Manville Coalinga Remedial Investigation Report March 1990.
U.S Environmental Protection Agency, Region IX. Record of Decision, City of Coalinga Operable
Unit of the Atlas Mine and Johns-Manville Coalinga Asbestos Mine and Mill NPL Sites. July
19, 1989.
12

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Atlas /'tsbestos Mine Site
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From Feasibility Study Report,
Atlas Asbestos Company Site;
EPA; March 1990

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FEASIBILITY STUDY REPORT
for the
ATLAS ASBESTOS COMPANY SITE
FRESNO COUNTY, CALIFORNIA
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION IX, SAN FRANCISCO
MARCH 1990

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part as a result of direct bank and bed erosion by streams and tributary
rivulets coursing through sines and stockpiled vaste material. Asbestos is
also introduced into the streams as a result of erosion of undisturbed
asbestos sources (i.•.* exposed serpentine outcrops and residual soils).
Froa the site, the streaas flov into Vhite Creek, vhich also drains a
significant portion of the Nev Idria serpentinite mass. Vhite Creek
drains into Los Gatos Creek, and Los Gatos into the Arroyo Pasajero.
Vaters of the Arroyo Pasajero then flov into the BOR ponding basin
bordering the California Aqueduct. In this vay, asbestos-laden sediments
froa the site are routinely deposited vithin the basin and adjacent areas.
During high voIum flood conditions, asbestos-laden vaters from the ponding
basin are released directly into the California Aqueduct. Asbestos then
finds its vay into the drinking and agricultural vater supply of various
users of the aqueduct that do not have sufficient filtration facilities.
Asbestos is introduced into the atmosphere via the air pathvay from
numerous regional sources. These sources include anthropic (related to
human activity) sources vithin the Nev Idria serpentinite mass such as
mines and related facilities, in addition to natural undisturbed sources
such as asb«stos-rich serpentine soil and barren outcrops of serpentine
rock. The rate of asbestos dust emissions from the Nev Idria mass,
especially froa aine and stockpile areas, is accelerated by the continuing
incursion of vehicles in these areas.
Regional sources of airborne asbestos outside the Nev Idria mass include
dry deposits of asbastos sediments in the ponding basin, streambeds. and
floodplains, that receive vaters drained froa the Vhite Creek watershed.
Asbestos froa these sources may be entrained into the atmosphere via the
air pathvay by natural vind erosion and as a result of intrusive activities
such as ploving and harvesting. Asbestos sources also include deposits in
the city of Coalinga resulting froa the processing and transportation of
asbestos matarial in tovn froa regional mines as historically, the city of
Coalinga contained asbestos processing and trans-shipment facilities.
4

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Woodward-Clyde Consultants

PROJECT VICINITY MAP
1-1 !
1-3

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used to characterize the nature and extent of contamination. The results
of the sampling were also used in support of numerical modeling studies of
contaminant transport dynamics. The purposes of the numerical modeling
studies vere to estimate the volume and rate of asbestos migration from the
site, md the relative contribution of the site to environmental
concentrations of asbestos in surface vaters, streambed sediments, and air
vithin a region that includes many other man-made and natural potential
sources; and to support the endangeroant assessment conducted for the site
and study area. The purpose of the endangerment assessment vas to identify
and quantify, if possible, threats to public health and the environment
from site and regional conditions.
A complete description of these activities and a presentation of their
results are contained in the Remedial Investigation Report. The results of
the sampling and site and study area characterization are summarized and
discussed belov. They are preceded by a topical discussion of asbestos
toxicity and current detection methods for asbestos for various media.
Asbestos
Asbestos is a generic tern used to describe a group of naturally occurring
fibrous hydrated silicate minerals. The asbestos mineral found in the Nev
Idria serpentinite mass is chrysotile. Chrysotile fibers have an
elongated, needle-like structure. Asbestos fibers have been widely used
for their high tensile strength and flexibility and their noncombustible.
nonconducting, chemically resistant properties.
Health Effects of Exposure to Asbestos
The adverse human health effects from exposure to asbestos are extremely
serious. Asbestos is a known human carcinogen that also causes other lung
diseases. Asbestos has been thoroughly examined in numerous
epidetiiological studies. The incurable life-threatening diseases that have
been linked to asbestos are asbestoses, lung cancer, and mesothelioma.
1-12

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Atlas /Lsbestos Mine Site
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Atlas Remedial Investigation Report and
Phase I of Johns-Manville Coalinga Remedial Investigation Report;
EPA Region IX; March 1990

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ATLAS REMEDIAL INVESTIGATION REPORT
and
PHASE I OF JOHNS-MANVILLE COALINGA
REMEDIAL INVESTIGATION REPORT
for
THE ATLAS AND JOHNS-MANVILLE COALINGA SITES
FRESNO COUNTY , CALIFORNIA
Prepared for
U.S: ENVIRONMENTAL PROTECTION AGENCY
REGION IX. SAN FRANCISCO
MARCH 1990

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EXECUTIVE SUMMARY
''he Adas asbes*:s mine and Johns-Manville Coalinga asbestos ro-i 11 sices
have been the subject of a Comprehensive Environmental Response.
Compensation and Liability Act (CERCLA) Remedial Investigation
.'Feasibility Study (RI/FS) conducted under the REM II contract becveen
:he U.S. Environmental Protection Agency (EPA) and Camp, Dresser, and
UcKee Inc. by Voodvard-Clyde Consultants (WCC) under contract to the EPA.
The Johns-Manville Coalinga RI data is only partially presented in this
document. Southern Pacific Land Company (SPLC) (nov Icnovn as Santa Fe
Pacific Realty Corporation), one of the Johns-Manville Coalinga sice
sotentially responsible parties (PRFs), is concluding the Johns-Manville
Coolings sill sit* remedial investigation (RZ) and is undertaking the
entire Johns-Manville Coalinga mill site feasibility study (FS) under EPA
jversigbt.
Tho Johns-Manville sine pits, known as the Christy Pit and Jensen Pit,
lave not been extensively studied in either the SPLC or EPA/VCC RI.
Those sines aro being addressed through the EPA regional study entitled
"Characterization of Disturbances Related in Mining and Exploration in
the New Idria/Coalinga/Table Mountain Study Region."
The Atlas asbestos site consists of asbestos sine pits, asbestos mill
facilities, .and asbestos tailings piles. The Johns-Manville Coalinga
mill sits contains asbestos sill facilities, asbestos tailings piles, and
associated open pit sines. The Atlas site is located approxiaately 18
siles northvsst of tha city of Coalinga, and the Johns-Manville Coalinga
mill and sins situ are located near the Atlas site, approximately 14
siles froa the city of Coalinga, in Fresno County, California. The mine
and sill facilities at the Atlas site and Johns-Manville Coalinga sices
are no longer in operation.
Asbestos was first identified as a possible probles when excessive
amounts of asbestos vere found in the California Aqueduct in 1980 by the
California Oepartsent of Water Resources (OVR), and the Atlas and
1

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Asbestos is a human carcinogen which is known to cause asbestosis, lung
cancer, and mesothelioma. Associated vith asbestos exposure are cancers
of the larynx, pharynx, gastrointestinal tract, kidney, and ovary, and
respiratory diseases such as pneumonia.
1.1	OBJECTIVES OF REMEDIAL INVESTIGATION
The objectives of the Remedial Investigation vere:
1)	To attempt to quantify the amount of airborne and
vaterborne asbestos presently being released from the
Atlas mine and Johns-Manvill« Coalinga mill site;
2)	To estimate the potential public health risk related to
air and water contamination in the area; and
3)	To provide data for the development and evaluation of
potential remedial actions.
Vithin the Los Gatos Creek drainage area, the Atlas and Johns-Manville
Coalinga sill tailings represent approximately 902 of the asbestos mill
tailings. However, the total of these mill tailings represents about 200
acres, or 1/3 square mile, compared to approximately 6 square miles
of drainage comprised of natural slopes in the New Idria serpentmite
mass. Tailings refer to waste rock after the asbestos has been removed.
The relative percentage of asbestos contributions to stream runoff and
air-entrained asbestos, in addition to relative areas, depends on the
relative asbestos content and erodibility of the respective soil
materials.
1.2	SITE BACKGROUND
1.2.1 SITE DESCRIPTION
The terrain in the vicinity of the sites is rugged. Hill slopes range
from 5X to 65* averaging 10Z to 15X. Vegetation is sparse throughout the
site vicinity. At the higher elevations, the vegetation consists
primarily of mixed chaparral, in conjunction with yellow pine. Oak
1-2

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woodland vegetative communities are located in the lover, nonserpentine
elevations. In many localized areas, soil disturbances and subsequent
hill slope erosion have prevented or restricted the reestablishment of
vegetative communities. According to the U.S. Bureau of Land Management
(BUI), the reestablishment of vegetative communities has been primarily
restricted by the presence of micronutrient toxicities and soil nutrient
imbalances, coupled vith the semi-arid climate and historic mining
exploration and production activities (BLM 1983).
Atlas Site
The Atlas site is located on approximately 435 acres of federally owned
land, approximately 18 miles northvest of the city of Coalinga, Fresno
County, Calfornia. Ten acres of property directly under the mill
buildings are under State of California receivership for Vheeler
Property's failure to pay property taxes. The site lies just south of
the Saa Joaquin Ridge in Sections 31 and 32, Tovnship 18 South, Range 13
East, on the United States Geologic Survey (USGS) Santa Rita Peak
Quadrangle. Figure 1-1 locates the sites vithin California and Figure
1-2 presents the site locations vithin the Los Gatos Creek watershed.
The primary boundaries of the Atlas site for the purposes of this
Remedial Investigation are shown in Figure 1-3. The Atlas site lies
within tha Nev Idria serpentinite mass, a geologic body containing one of
tha world's largest chrysotil* asbestos fiber deposits. Deposits of
chroaiua, mercury, and other heavy metals are also found in the Nev Idria
serpentinite mass. The site ranges in elevation from 4,000 to 4,400 feet
above sea level. Major features of tha site include an open pit mine, a
mined or* stockpile area, abandoned mill facilities, and a 17-acre
process vaste tailings pile. Immediately south of the site are a number
of incised canyons vith Intermittent streams which drain the site and
areas above the site. These streams flow into Vhite Creek, which drains
the Nev Idria serpentinite mass.
1-3

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over thousands of acres of land betveen the communities of Huron, Fi/e
Points, and Stratford. Since the construction of the aqueduct m 1967.
floodvaters have flowed out of the arroyo in a northeast direction to a
levee 3 miles north of Huron, vhich diverts them into a basin. Here the
vater is retained as long as possible to allov sediment to settle out:
then, if necessary, the vaters are either released into the aqueduct
through four drain inlets at Gale Avenue, or are passed under and east of
the aqueduct through an evacation structure located betveen Highway 198
and Gale Avenue. Flovs passed under the aqueduct then travel east toward
Lemoore Naval Air Station. Controlling the aqueduct and the deposition
of floodvaters is the responsibility of the U.S. Bureau of Reclamation
and the California Department of Vater Resources (DVR).
1.2.2 SITE BISTORT
The primary asbestos operations started in the Los Gatos Creek area after
a "mining claim rush" in 19S9. Records of claim activity and a summary
of leasing and mining activity for the Atlas mine site and the
Johns-Manvllle Coalinga site are presented in Appendix E-5. The asbestos
ore source for the Atlas and the Johns-Manville Coalinga mills vas the
Nev Idria serpentinite mass, a body 14 miles long and 4 miles vide which
is rich in chrysotile asbestos.
Atlas Mill and Mine
In 1962 the Atlas Minerals Division of the Atlas Corporation acquired
title to a large block of claims and began mill construction at the Atlas
projeet site. Asbestos mining and milling at the Atlas site occurred
froa 1967 to 1979. During this period, the facility vas first ovned by
the Vlnnell Mining and Minerals Corp. (1967 through 1974), which sold the
facilities to Vheeler Properties in 1974. Vheeler Properties continued
operations until 1979, then filed for bankruptcy shortly after. The
Atlas property is ovned by the United States and administered by the U.S.
Bureau of Land Management (BLM). Ten acres of the property directlv
under the mill building have reverted to the State of California for
Vheeler Property's failure to pay delinquent property taxes.
1-8

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3.0 SITE CHARACTERISTICS
3.1 METEOROLOGY
3.1.1 GENERAL METEOROLOGY
The Atlas and the Johns-Manville Coalinga sites are located along the
eastern ridge of the San Joaquin Ridge, which is part of the Olablo Range
in vest-central California. The Olablo Range, along vith other segments
of the Coastal Range, separates the tenperate, marine coastal climatic
zone froa the arid, continental clioate of the San Joaquin Valley. This
physical barrier significantly contributes to the unique character of the
diaate found in this region. The terrain surrounding the alnes is quite
coaplex, vith considerable changes in local relief found over short
distances.
Tha cliaata of the ainlng region consists predoalnantly of tvo distinct
seasons. Those seasons, winter and suntr, are separated by relatively
short transitional spring and autuan periods. During these transition
periods, weather patterns generally fluctuate greatly, including
cliaatologlcal features froa both doainant seasons.
Vlnter is the rainy season. Most of the precipitation occurs in the form
of rain, although snov is possible ae either project site. The
probability of snow is greater at tha Atlas site than the Johns-Manville
Coalinga aill site prlaarlly because of tha higher site elevation
(approxiaately 4,300 feet at the Atlas site versus 3,000 feet at the
Johns-Manvllle Coalinga aill site). Suaaer precipitation is generally
Halted to occasional isolated showers associated with thunderstorm
activity generated by the strong surface heating of interior California
in coabination vith an influx of tropical aoisture at higher elevations
of the ataosphare. Overall, stora activity brings aeasurable
precipitation to tha region on only about 40 days par year. The mean
annual precipitation of the region is less than lS.inehas. Approximately
90Z of this annual total falls between Noveaber and April.
3-1

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Wind flov near Che surface is quite predictable and is greatly influenced
by the larger scale flov pattern of the San Joaquin Valley.. As is
generally found in mountainous terrain, an upslope/dovnslope flov regime
oecurs nearly every day at the mining sites. The exception is vhen
stronger veather-producing storm systems override this local and regional
diurnal flov. The usual scenario includes a nighttime drainage flov
through the canyon that eventually spills into the San Joaquin Valley.
During daylight hours, the thermal activity on exposed canyon surfaces
results in rising air and upslope vinds. In addition, this solar
radiation affects the atmospheric conditions in the San Joaquin Valley,
creating its ovn regional upvalley (northerly) flov that helps support
the upslope flov found near the mining district. This diurnal pattern is
repeated In the numerous canyons that branch off on both the Coast Range
and Sierra Nevada sides of the San Joaquin Valley, creating a complex and
interconnected boundary layer flov throughout a large region of central
California.
3.1.2 METEOROLOGY MONITORING RESULTS
Continuous meteorological monitoring in the vicinity of the Atlas site
and the Johns-Kanvillm Coalings mill site began in September 1985.
Monitoring continued far one year at the Coalinga station and for
slightly longer this tvo years at the Atlas station. For nearly all of
the saapllng period, the meteorological parameters continuously monitored
included teaperature, vind speed and direction, precipitation, and
relative huaidity*
Additional short-tera aeteorologleal monitoring stations vere established
at the Coalinga airport and the mouth of Los Gatos Creek Canyon, which :s
the mala canyon leading to the mining district froa the San Joaquin
Valley. This aonitoring vaa performed as part of an extensive air
saapllng prograa that oeeurred In Septeaber and early October 1987. The
saapllng prograa also included pilot veather balloon (pibal) tracking at
nuaeroua locations around the project area. Data froa these pibal
soundings provide a vertical vind profile of the boundary layer flov
patterns of the region during the sampling period.
3-3

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near th« rldgeline of the San Joaquin Ridge, experienced vmd speeds
greater than 3.5 m/s (12 mph) over 10 percent of the tine, vlth a
significant number of hourly values exceeding 11.1 m/s (24.3 mph).
Average daytime vind directions at the Johns-Manville Coalinga mill sice
and the Atlas site were from the southeast and souchvest sectors,
respectively. This vu most apparent when the circulation pattern vas
veil established, as displayed by Figures 3-6, 3-7, and 3-8. The typical
afternoon vind direction in the vicinity of the community of Coalinga vas
froa the east or northeast. Coabining the results froa these three
stations indicates a clockvlse spiral or rising eddy in the daytime
airflov trajoctories that begins in tha San Joaquin Valley and advances
toward tha coastal ridgas.
Figures 3-6 through 3-9 and 3-10 through 3-13 present vind direction
frequency distributions for vind spaed classes 0-1.8 a/s, 1.8-3.3 m/s,
3.3-3.4 m/s, 3.4-8.3 a/s, 8.3-11.0 a/s and vind speeds greater than 11.0
a/s. Tha distributions are for hourly averages for one year of data froa
the Johns-Manvllle Coalinga aill site and tvo years froa tha Atlas site.
No hourly vind speed averages greater than 8.3 a/s vera seasured at the
Johns-Manvllle Coalinga aill site. These figures clearly illustrate that
high vind evonts occur alaost exclusively vhile the vind is froa the
south. At the Atlas site, local topography channels south vlnds to
south-southvost or southwest. At the Johns-Manvllle. Coalinga aill site,
regional south winds are channeled to south-southeast or southeast. The
occurrence of high wind speeds froa only a narrow range of directions
strongly influences tha transport patterns of aaterials entrained by vind
erosion. This is discussed further in Section 3.2.1.
A cross-sectional evaluation of the vind fields, as determined froa the
pibal soundings, indicates that tha daytiaa upslopa vlnds eventually
becoaa incorporated into the larger scale circulation patterns over the
San Joaquin Valley. However, this aerging of flows oecurs at elevations
veil above tha San Joaquin Valley floor and either at or above the usual
afternoon aixing height. The daytime circulation pattern develops in
response to the theraal activity in tha boundary layer. The depth of
3-10

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this layer increases until it reaches a mid-afternoon maximum; hovever.
It decreases vlch elevation. Vhile the summer afternoon mixing depth vas
around 3,900 feet above ground level in the San Joaquin Valley, this
depth vas reduced to around 2,400 feet m the mining region. Typical
daytime vind speed maxima near the surface ranged betveen 4.0 and 6.0 n/s
(8.9 and 13.4 raph), or about 2SZ lover than nighttime maximum values.
Nighttime drainage vinds begin in the vicinity of the ridgeline and
progress dovn through the canyons, eventually spilling into the San
Joaquin Valley. The average speed and duration of the nighttime drainage
vinds are sufficient to advect emissions froa the project sites to the
city of Coalings and beyond. The drainage flov at the Atlas site is
extreaaly vaak as this site is near the point of flov origin, vhile the
dovnslopa flov at the Johns-Hanville Coalings mill site is more
established. The average nocturnal flov monitored at the Coalinga
station vas greater in magnitude than the daytiaa flov. Nighttime pibal
soundings at vsrious launch sites from the mining region to the valley
floor indicated thst this drainage flov increases in depth as the flov
advances tovsrd the entrance of the San Joaquin Valley, when the
nigfattiM flov reached its oaxioua, this depth vss typically 900 feet in
the vicinity belo* the aines, expending to near 2,000 feet at the nouth
of Los Gstos Creak Canyon. These depths v«re considerably lover than
corresponding daytiae flov depths. The vertical profile of vind speed
generally revealed a core of higher vind near the center of this layer.
The aaxiaua value vas coaaonly betvaen 3.0 and 8.90 m/s (11.2 and 17.9
aph).
3.2 SURFAC8 VATER STDROLOGT
3.2.1 FLOV PATTERNS
examination of tha record for Los Gatos Creek (Station 11224500 - Section
2.2.1), indicates thst aeasurable surface vater flovs occur generally in
the vlnter and spring. During the sumaar and fall months, gaged flov?
are extreaaly lov to nonexistent. Average annual volume of vater gaged
la approxiaately 4,220 acre-feet.
3-21

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co the sice and co S13. These seemingly anomalous resulcs suggest
several interpretations:
o Plov from S20 vas absorbed by the tailings. Values at
S15 represent local hillside runoff from belov the
tailings and possibly some seepage from the tailings.
Note from Table 4-8 that che flow at S15 vas only about
0.1 cfs.
o Locally, airfall has probably eoncribuced a significant
amount of asbestos to the soils, especially vhen the
mills were in operation and before particulate emission
control vas implemented. This hypothesis is supported
by the similarity in concentrations betveen S15 and
S16, and the large difference betveen S16 and the more
reaote S02 and S04.
o High flovs and asbestos loading at S15 probably occur
only vhen rainfall is sufficient to overflow che
tailings pile and further erode the large gully
observed there.
Belov the Atlas site, Stations S06, S07, and S09 all sample streams
draining both the N«v Zdria serpentinite mass and the Atlas site.
Concentrations are all similar and relatively high, ranging from
2.3 x 107 to 6.6 x 107 MFL. These values are consistent vith the
concentration of 9.3 x 107 MFL measured further dovnstreaa at Sll. The
lov value at SOS (1.9 x 10^ NFL) is somevhat anomalous, as che drainage
Includes both the New Idria serpentinite mass and ocher mine sices.
In the imaediate vicinity of the Atlas site, measured asbestos
6	8
concentrations in streaas ranged from 2.7 x 10 to 3.1 x 10 MFL.
It is interesting to note that the three highest asbestos concentrations
measured by VCC/BPA all occurred at stations above the Atlas site and
Johns-Manville Coalinga mill site. There are several possible reasons
for this, ineludingi
o Release of asbestos from other disturbed areas,
including roads, upslope from che Johns-Manville
Coalinga site;
4-17

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The Levine-Fricke/SPLC data give a valid glimpse of the asbestos
transport on the falling limb of the hydrograph. It does not describe
the heavier release and transport of asbestos during the more intense
part of the storm.
4.2.2 OTHER RESULTS
Long Asbestos Fibers
VCC/EPA saaples shov that asbestos fibers longer than LOu were found in
only five surface vater saaples: S03, S07, S09, 312, and S21. 303, S07,
and S09 are all located on Vhite Creek belov the Atlas site and 312 and
S21 are actually within the Atlas site. Vhen detected, long fiber
concentrations ranged from 7.2 x 10^ to 4.4 x 106 NFL.
The concentration of asbestos fibers generally tends to increase moving
upstreaa froa saaples S03 to S09 and S07, until it reaches a maximum at
S21 located at the Atlas site. The concentration at S12, located on the
Atlas «ill tailing pile* vas slightly less than at S21, located on the
first order tributary to Vhite Creek. At S03, located on Pine Creek
above the confluence vith Vhite Creek, a duplicate sample vas anal/zed in
vhich long fibers vera undetected. Sample locations are shovn on Figures
4-1 and 4-2.
Long-fiber concentration as a percent of total asbestos concentration
shovs the saaa general trend, as does the total asbestos concentration,
to increase moving upstreaa toward the Atlas site. The ratio at S12,
located on the Atlas mill tailings pile, vas 0.8X. The ratio increased
to reach a aaxlaua of 6.3Z at S21t a first order tributary of Vhite
Creek. Long fibers vere not found on the direct route from S09 to S03.
This trend suggeats a source of long-fiber asbestos in the vestern aiea?
of the Atlaa site, and probably very fev long-fiber asbestos
elsevhere in the study area.
The Levine-Pricke/SPLC data for the Johns-Hanville Coalinga mill site
shoved asbestos fibers >10u to be belov detection limits at all stations.
4-21

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of chrysotile frequently have very small fibers not visible under a
polarized microscope. All asbestos Identified was ehrysotile.
All VCC/EPA samples collected in close proximity to the Atlas and
Jshns-Hanvilla Coalinga mill sites had contents of asbestos ranging from
undetected to 6Z asbestos. Undetected means that there vere no asbestos
fibers observed in the saaple squares counted in a given analysis (see
Section 1.4). The highest concentration, 6Z was from samples collected
just belov the Atlas site. The sample collected from White Creek, vhich
d::ains the Nev Idria serpentinite mass, contained 2Z asbestos by PLM
analysis and 10Z asbestos by TEH analysis confirming the presence of
asbestos as a contaainanc being transported out of the Nev Idria
sorpentinite um. The Pine Canyon Creek saaple above the confluence of
Los Gatos contained 2Z asbestos, indicating there is some quantity of
asbestos being transported from the Johns-Manvllla Coalinga mill sice,
but the soil saaples suggests it is less than the Atlas site
contribution. The PLM results of the other tvo hot spots near the Arroyo
Ptsajero vere less than 1Z asbestos content by PLM and more than 20Z by
TIM, indicating that the asbestos fibers present in the saaple v«re
piobably very short or had been transformed by the transport process so
they vere not identifiable as asbestos under a polarized light
microscope.
The highest levels of PLM asbestos content vere measured at one given
point by VCC/EPA immediately outside the Atlas site vhile the highest
levels by TEM vara 100Z on the mine tailings. The samples collected from
streams feeding into Los Gatos Creek belov the sites had no asbestos
detected by PLM above their confluences vlth Los Gatos Creek. The
background saapla on Varthan Creek (near the city of Coalinga) contained
less than 1Z asbostos by PLM. The samples collected on Los Gatos Creek
belov the confluence of Jacalitos and Zapato Chino Creeks contained le??
than 1Z asbestos by PLM and 21Z and 26Z asbestos by TEM. The road
saaples collected near the Atlas mill site contained from 1Z to 4S
asbestos.
4-25

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not. The sedimentary soils specifically encompass sediments transported
and deposited in streaobeds as a result of hydraulic action: they do not
include aeolian (vindblovn) deposits or material directly transported as
a result of soil instability.
The nominal erodibility factors for the source materials vere estimated
using the SCS nomograph method. The following K factors vere determined:
Asbestos Source Material	Erodibility (K) Factor
Asbestos Tailings Piles	0.28
Asbestos Mine Surfaces	0.18
Serpentine Soils	0.28
Sedimentary Soils	0.32
A fifth category, classified as "Hentine" by the SCS, vhich describes the
Nev Idria serpentinite mass rock outcrops, vas estimated to have a K
faeeor of 0.10.
On this basis, qualitative comparisons of the relative erodibility of the
general source materials vere made. Vithin the Nev Idria serpentinite
mass, the Hentine rock outcrops are the least erodible. The asbestos
mine surfaces are approximately tvice as erodible as the outcrops. The
asbestos tailings piles, asbestos-rich serpentine soils, and sedimentary
soils are approximately three times as erodible as the outcrops.
4.4 AIR SAMPLING RESULTS
Airborne asbestos concentrations vere calculated for the samples
collected during the summer 1986, vinter 1987, and summer 1987 sampling
phases. The concentrations vere expressed in asbestos fibers per actual
cubic meter, asbestos structures per actual cubic meter, asbestos -nass
(ng) per actual cubic meter, and phase-contrast microscopy equivalent
(PCMB) structures per actual cubic meter. Asbestos structures im:i'"it-
fibers, clusters, bundles, and matrices. Phase-contrast microscopv
4-54

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differences were observed, there may, in face, be a difference in the
mean values-. More samples would be required to demonstrate this.
Table 4-15 summarizes the geometric mean asbestos fiber, structure, and
mass concentrations for all valid daytime and all valid nighttime samples
collected during each sampling phase at each location. No high vind
events greater than 10 m/s, occurred during any sampling phase. For this
reason, it is unlikely that vind erosion from the tailings piles occurred
during these periods. See Section 3.2.1 for further information
regarding vind erosion threshold velocities.
4.4.1 ATLAS AND JOHNS-MANVTLLZ COALINGA AIR SAMPLING EFFORTS
Sea Figures 2-1 through 2-7 for locations and Table 4-15 for results.
Sumner 1986 Sampling
The results of the air sampling and analyses by VCC/EPA for this phase
indicated that the asbestos concentrations at all of the sampling
locations vere higher than generally accepted "background" levels (about
100 fibers/actual m^), and that the concentrations measured near the
Atlas site and the Johns-Hanville Coalinga mill site vere not
significantly differene than those at the Coalinga fire station. Mean
asbestos fiber and structure concentrations vere significantly higher
during the nighttime sampling periods dovnslope from the Johns-Hanville
Coalings mill site (location 23) than upslope froa the Johns-Hanville
Coalings alii site (location 24). No other significant differences vere
observed based on VCC/EPA data, between the nesn concentrations measured
at the either of the pairs of samplers located upslope and dovnslope of
each of the tvo project sites. Note that to produce statistically
significant differences, many more samples vould have been needed n»sr a
period of many months or years, representing an extremely high i --
Table 4-IS for results).
4-56

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UUC 4-15
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further dovnstreaa, concentration vas 2,940 ug/1. The EPA drinking vater
standard for chroaiuo is SO ug/1, and che hazardous vaste standard is
5,000 ug/1.
Chroaiua vas "undetected" in Oiaz Canyon at S04 and only 9.2 ug/1 (belov
contract-required detection limits) in Los Gatos Creek above Vhite Creek
at S02.
Zinc vas found in all vaters tested, in concentrations ranging from 12
ug/1 (belov contract-required detection limits) to a high of 1,041 ug/1
at S23, on the Johns-Manville Coalinga mill site. Concentrations
measured at the Johns-Manville Coalinga mill site exceeded the one
concentration obtained at the Atlas site, 106 ug/1 at S21. Belov che
Atlas site, the concentration increased to 387 ug/1 at S07, and the
saaples collected at both S14 and S22 contained a measured concentration
of 347 ug/1 at S06. At the confluence of Vhite and Pine Creeks, similar
concentrations vare found: 499 ug/1 at S10, vhich drained the
Johns-Manville Coalinga aill site, and 482 ug/1 at SI1, draining the
Atlas site. Purther dovnstreaa, at S03, the concentration had increased
to 655 ug/1. The EPA drinking vater standard for zinc is 3,000 ug/1.
Zinc vas present at 12 ug/1 in Diaz Canyon (S04) and 45 ug/1 in Los Gatos
Cieek above Vhite Creek (S02).
4.5.3 DISCUSSION—METALS
The metals analyzed for the prograa, mercury, chroaiua, and zinc, are
present in finite aaounts in the streaos studied. The data generally
siggest, rather than define, sources. The increase in chromium
concentration from 272 ug/1 at S07 and 1,330 ug/1 at S06 to 3,640 ug/1
dovnstreaa at Sll implies a possible natural source vithin that
particular reach. The one saaple analyzed at che Atlas site is
ir.conclusive about the Atlas site sources. At the Johns-Manville
Coalinga mill site, on the other hand, Station S23 revealed the highest
concentrations found of chroaiua and zinc and the third highest
concentration of mercury.
4-65

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scenario is developed based on assumptions about the environmental
behavior and-transport of asbestos, and the extent, frequency, and
duration of exposures. These factors are used to predict potential
intakes of asbestos for both an average and a maximum plausible exposure
case.
6.3.1 POTENTIALLY EXPOSED POPULATIONS
There are several groups of persons vho may potentially be exposed to the
contaminants originating at the Atlas site and the Johns-Manville
Coalinga sill site. Individuals are known to use the sites and other
nearby areas for recreational off-road vehicle driving. In one report
(Cooper et al. 1979), motorcyclists in the N«v Idria serpentinice region
vere found to be exposed to between 0.3 and 3.3 f/ca^ while riding on one
of the trails. In addition, the sites and surrounding areas are known to
be used by hunters, caapers, and hikers. There are also 30 to 100 cattle
ranchers and other individuals currently living downslope of the sites
(e.g., in areas near the Pine Canyon drainage area). The Hansen
residence is the closest residence to the Atlas site and the
Johns-Maavllle Coalinga aill site.
Higranc vorkers reportedly live near the town of Huron, approximately 23
miles east-southeast of the sites. The population of aigrant workers in
this area fluctuates widely depending on tha season, with a population of
3,000 growing to approxiaataly 12,000 during the cotton harvesting
season. Finally, there are potentially exposad individuals living on the
Harris Ranch or Teilea Ranch, and in the towns of Coalinga, Hanford,
Idria, Stratford, Five Points, Kettleaan City, Priest Valley, Lonoak,
Panoche, and Avenal. The 1987 population of the town of Coalinga, the
closest town to tha sites, was 7,834 (based on Coaaunity Econoaic
Profile).
6-24

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observed under present conditions at the sites, visible emissions can be
exaected when-vehicles (e.g., four-wheel-drive) are driven on the
tailings piles and asbestos risk soils in the site areas. The potential
for increased erosion and weathering of the piles in the future further
suggests that the potential for visible emissions may increase over time.
Reuedial activities that disturb contaminated materials will also Likely
result in visible emissions.
Asbestos concentrations measured- in surface vater near the Atlas site and
th«i Johns-Manville Coalinga mill site exceed both the ambient vater
quality criterion for protection of human health and the proposed maximum
contaminant level goal (KCLG). None of the sampled surface vater bodies
3aiipled during the RI are being used or are planned to b« used as
dr:lnking sources. The California Aqueduct, which was not sampled during
chu RI, is a major source of drinking water. Although nose users of
aqueduct water are expected to have access to only treated water, there
aro numerous small users between Johns-Manville Coalinga and the
District's treatment facilities whieh may provide minimal treatment of
tho water prior to use. Therefore, risks from ingestion of both treated
and untreated aqueduct water were evaluated using aqueduct water
concentrations obtained from both historical data and modeling conducted
by VCC, Levine-Pricke, and ICP/Clement.
Because ARARs were not available for all of the sampled environmental
media, a quantitative risk characterization was also conducted. In this
evailumtion, estimates of potential chemical intakes through each pathvay
identified for evaluation vere combined with asbestos-specific toxicity
values to predict potential risks associated with the Atlas site and the
Johns-Manville Coalinga mill site. Por each pathway, an exposure scenario
vaji developed based on assumptions about the environmental behavior and
triinsport of asbestos, and the extent, frequency, and duration of
exposures. These factors were used to predict potential exposures to
asbestos for both an average and a maximum plausible exposure case.
6-98

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TABLE 6-20
SUMMARY OP POTENTIAL RISKS ASSOCIATED WITH EXPOSURE PATHWAYS
QUANTITATIVELY EVALUATED FOR THE ATLAS AND JOHNS-MANVILLE COALINGA SITES
Excess Upper Bound
Lifetime Cancer Risk
Exposure Pathway
Average
Case
Maximum
Plausible
	Case
Inhalation of Asbestos
in Ambient Air
-Lifetime Exposure to Off-Site
Residents: Hansen Residents
~	Males - Atlas Only as Source
Mesothelioma
Lung Cancer
~	Pemales - Atlas Only as Source
Mesothelioma
Lung Cancer
Males - Johns-Manville Coalinga
Only as Souree
Mesothelioma
Lung Cancer
~	Pemales - Johns-Manville Coalinga
Only as Source
Mesothelioma
Lung Cancer
« Males - All Sources
Mesothelioma
Lung Cancer
~	Female - All Sources
Mesothelioma
Lung Cancer
-Lifetimm Exposure to Other
Off-Site Residents
Avenml
Sites Only am Sources
All Sourees
~	Tovn of Coalinga
Sites Only as Sources
All Sources
~	Pive Points
Sites Only as Sources
All Sources
+ Hanford CHF Station
Sites Only as Sources
All Sourees
~	Harris Ranch
Sites Only as Sources
All Sources
2.0E-05
2.0E-05
3.0E-03
6.0E-06
3.0E-08
3.0E-08
4.0E-08
8.0E-09
3.0E-04
2.0E-04
4.0E-04
7.0E-03
5.0E-08
8.0E-06
1.0E-07
4.0E-05
1.0E-07
6.OB-OS
5.0E-08
6.0E-06
1.0E-07
9.0E-03
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
6-100

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TABLE 6-20 (Cont.)
SUMMARY OP POTENTIAL RISKS ASSOCIATED VITH EXPOSURE PATHVAYS
QUANTITATIVELY EVALUATED FOR THE ATLAS AND JOHNS-HANVILLE COALINGA SITES
"™"	Excess Upper Bound
Lifetime Cancer Risk
Maximum
Average Plausible
Exposure Pathway	Case	Case	
*	Huron
Sites Only as Sources	6.0E-08	NA
All Sources	4.0E-05	NA
*	Idrla
Sites Only as Sources	2.0E-07	NA
All Sources	3.0E-05	NA
+¦ Kettleaan City
Sites Only as Sources	3.0E-08	NA
All Sources	2.0E-03	NA
*	Lonoak
Sites Only as Sources	3.0E-08	NA
All Sources	1.0E-03	NA
*	Panoche
Si eta Only as Sources	5.0E-08	NA
All Sources	6.0E-07	NA
*	Pine Canyon
Sites Only as Sources	2.0E-06	NA
All Sources	7.0E-05	NA
+ Priest Valley
Sites Only as Sources	2.0E-06	NA
All Sources	1.0E-05	NA
*	Stratford
Sites Only as Sources	5.0E-08	NA
All Sources	7.0B-06	NA
*	Telles Ranch
Sites Only as Sources	1.0E-06	NA
All Sources	4.0E-06	NA
-Intermittent Exposure of Hikers,
Papers, and Hunters On-Site
*	Atlas Site
Sites Only as Sources	7.0E-06	3.0E-05
All Sources	8.0E-06	3.0E-05
*	Johns-Hanville Coalings Site
Sites Only as Sources	7.0E-08	3.0E-07
All Sources	1.08-06	6.QE-06
Inhalation of Asbestos During
Dust-generating Activities
-Off-Road Vehicle Use On-Site
*	Atlas Site
Trucks	5.0E-04	4.OE-O1
Motorcycles	4.0B-03	2.0E-02
6-101

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TABLE 6-20 (Cone.)
SUMMARY OP POTENTIAL RISKS ASSOCIATED VITH EXPOSURE PATHWAYS
QUANTITATIVELY EVALUATED FOR THE ATLAS AND JOHNS-MANVILLE COALINGA SITES
Excess Upper Bound
Lifetime Cancer Risk.
Exposure Pachvay
Average
Case
Maximum
Plausible
Case
+ Johns-Manville Coalings Site (EPA Data)
Trucks	8.0E-04	6.0E-01
Motorcycles	7.0E-05	3.0E-02
*	Johns-Manvllle Coalinga Site (L-P Data)
Trucks	1.0E-04	1.0E-01
Motorcycles	9.0E-06	6.0E-03
-Agricultural Tilling in the
Settling Basin
«• Mesothelioma	5.0E-04	6.0E-03
*	Lung Cancer	8.0E-04	1.0E-02
Ingestion of Asbestos
Fro« California Aqueduct
-Total Fiber Concentrations
*	Arroyo Pasajero
No Treatlent	2.0E-04	3.0E-03
75* Reaoval	5.0E-05	6.0E-04
95XoReaoval-	9.0E-06	1.0E-04
Upstreaa
No Treatment	5.0E-03	4.0E-04
75X Reaoval	1.0E-0S	1.0E-04
952 Reaoval	3.0E-06	2.0E-05
*	Dovnscreaa
No Treataant	1.0B-04	2.0E-03
75X Reaoval	3.0E-05	4.0E-04
93* Reaoval	6.0E-06	8.0E-05
-Greater Than 5-u Plbar
Concentrations
*	Upstreaa
No Treataant	3.0E-07	3.0E-06
73X Reaoval	8.0E-08	7.0E-07
95X Reaoval	2.0E-08	1.0E-07
Downstreaa
No Treataant	1.0E-06	6.0E-05
73X Reaoval	3.0B-07	1.0E-05
95X Reaoval	7.0E-08	3.0E-06
-EPA Modeled 10-u PIbar
Concentrations
*	Contribution of Adas Slta
No Treataant	6.0B-07	1.0E-0S
75X Reaoval	1.0E-07	4.0E-06
952 Reaoval	3.08-08	7.0E-07
6-102

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7.0 SUMMARY AND CONCLUSIONS
7.1	SUMMARY
The Remedial Investigation (RI) for the Atlas and the Johns-Manville
Coalinga Asbestos sites, listed on the National Priorities List, included
field investigations in the areas of surface vater, soil, and ambient air
sampling at the sites and in the surrounding areas. The surface vater
sampling covered the region surrounding the sites and dovnstream to Los
Gatos Creek; the soil sampling covered the sites and the area extending
to the California Aqueduct near the tovn of Huron; and the air sampling
covered the area of the Atlas site and the Johns-Manville Coalinga mill
site as veil as population centers in and around the study area. Tvo
computer modeling efforts vere done. The first vas concerned vith the
detachment and transport of sediment and asbestos by surface vater runoff
from the upper Los Gatos Creek watershed to the city of Coalinga. The
second vas concerned vlth the estimation of the average annual release
output of airborne asbestos from the Atlas site, the Johns-Manville
Coalinga mill site and from all other sources, and the areal distribution
c>f asbestos. A baseline risk assessment vas done.
The contaminant of concern at the Atlas site and the Johns-Manville
Coalinga mill site is asbestos. Although heavy metals are present, there
vas no evidence chat they are present in concentrations above levels of
concern, or are related to past disposal practices at the sites.
Ilierefore, the focus of this RZ vas restricted to asbestos.
"he potential contaainant sources identified at the beginning of the RI
were the asbestos tailings piles, asbestos mine surfaces, asbestos-rich
natural serpentine soils, and natural sedimentary soils. The erodibility
of these materials vas estimated to evaluate their relative contributions
:o the off-sito transport of asbestos in the surface vater pathvay. The
i:ock outcrops present near the Atlas site vere the least erodible. The
•isbestos mine surfaces vere approximately tvice as erodible as the
7-1

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o The tvo sampling stations vhose watershed did not include the Nev
Idria serpentinite mass and ware generally distant from the sices
shoved approximately four orders of magnitude lover
concentrations of asbestos than stations closer to the sices.
The results of the air quality modeling vhich vas based on the
meteorological data and soil samples collected by VCC/EPA during 1986-87
indicate that the highest airborne asbestos concentrations are expected to
the northeast of the Atlas site and the Johns-Manville Coalinga mill sice.
This expectation reflects the fact that high vinds at the sites occur only
froa the south to southwest. During high vind events, the asbestos
emission rates due to vind erosion from the Atlas tailings pile and mine
area are quite high. The frequency of these vind ev«nts is lov, but the
asbestos emitted during these periods contributes substantially to the
total annual emissions from the tvo sites. During periods of lover vind
speeds, asbestos emissions from the sites are from vehicle travel on the
unpaved roads only. The majority of these roads are in and around the
Atlas site.
The total annual average asbestos concentrations for each sampling location
vere estimated by adding the estimated concentrations from sources outside
of the Atlas site and the Johns-Manville Coalinga mill site to the modeled
concentrations associated vith emissions from the sites. The modeled total
average annual concentrations indicate that' over 9SZ of the airborne
asbestos in the population centers of the cities of Coalinga, Huron, Five
Points, Avenal, and Hanford vere from direct sources outside the tvo sices.
The modeled average annual asbestos mass concentrations for the population
near the sites vere mere heavily affected by the site contributions.
The six most important potential human pathways of exposure to asbestos
vere evaluated for the Atlas site and the Johns-Manville Coalinga mill sice
in the baseline risk assessment. The pathways of concern vere:
o Lifetime exposure of individuals by Inhalation of ambient air;
o Intermittent exposure of individuals by inhalation of air on-sice
during specific activities, such as use of recreational offroad
vehicles;
7-A

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Atlas Asbestos Mine Site
Mining Waste NPL Site Summary Report
Reference 3
Excerpts From Atlas Asbestos Company Superfund Site, Fact Sheet;
EPA Region IX; April 1990

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S> Atlas Asbestos Co. Superfund Site
EPA	Fresno County, CA
United States Environmental Protection Agency, Region IX
April 1990
EPA ANNOUNCES PROPOSED CLEAN-UP PLAN
The U.S. Environmental Protection Agency (EPA) has determined its preferred alternative for
controlling; the asbestos contamination at the Atlas Asbestos Company Superfund site (the Atlas Mine
Site) EPA's proposed plan involves control of asbestos in three separate areas:
1)	Atlas Mine Area: Stream diversions and sediment trapping dams are
proposed to minimize the release of asbestos into local creeks. Revegetation
is proposed to stabilize the area and minimize erosion and future releases of
asbestos. The road through the Atlas Mine Area would be paved to reduce
airborne asbestos emissions. The current access restrictions to the Atlas Mine
Area would be improved.
2)	Clear Creek Management Area: EPA is proposing no action at this time
because of actions being taken by the U. S. Bureau of Land Management
(BLM). BLM will revise its Clear Creek Management Plan to minimize asbes-
tos exposure. This decision is discussed in greater detail under the Proposal
for the Clear Creek Management Area on page 7.
3)	Ponding Basin: EPA is proposing no action at this time in the California
Aqueduct ponding basin near Gale Avenue (see figure 1) because of actions being taken by the U S. Bu-
reau of Reclamation and the California Department of Water Resources. One possible action being con-
sidered bv BLM is restriction of land use in an expanded ponding basin. This decision is discussed in
more detail under Proposal for Gean-up in the Ponding Basin section on page 7.
EPA's preferred alternative for the mine area and several other clean-up alternatives are described
in detail in the Feasibility Study (PS) now available at the information repositories listed on page 9 EPA
encourages you to review the FS and other site-related documents and provide your comments on the
alternatives described in this fact sheet. A document containing a more detailed explanation of certain
aspects ol the proposed plan (the Atlas Mine Proposed Plan Addendum) is also available. If you are
interested in receiving this document, call Debbie Lowe at 1-800-231-3075.
In this fact sheet
PAOI
~	Site Background 2
~	Results ot Initial 3
Investigation
~	Public Health	3
Evaluation Results
~	Summary of	4
Clean-up Options
~	EPA's Proposed 4
Clean-up Plan
Traduction en Espanol Adentro (Spanish Translation Available)
Este folleto contiene information acerca de la plan de accion que la Agenda para la Protection Ambfental
ha propuesto para oontrolar el peHgro de contamination por asbestos) en el local de la Compania de Atlas
Asbesto |s). Si Usted quiere recibir una traduction de este folleto en espanol, por favor, deja una mensaje con
la maquma para Debbie Lowe en el numero telefonico 'Toll Free': 1-800-231-3075.

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What is Asbestos?
Asbestos is a naturally occur-
ring mineral which has a fibrous
crystalline structure. Asbestos is
known to cause hmg cancer, meso-
thelioma, and other serious respi-
ratory diseases such as asbestosis
in humans.
Breathing airborne asbestos
fibers is the primary route of expo-
sure and poses the greatest health
risk, because once fibers enter the
lungs, the fibers can be trapped in
the body. Asbestos fibers may
also be swallowed in food and
water.
CLEAN-UP ALTERNATIVES
EPA's Proposed
Clean-up Plan
1
•

•








2

•
•








3











4











5

•
•
•



•



6

•
•
•




•


7









•

8

•








•
CLEAN-UP ALTERNATIVES
The purpose of the Feasibility Study (PS) is to de-
velop and screen potential clean-up alternatives based
on the findings of the Remedial Investigation. A range
of clean-up options were considered to address the
asbestos contamination at the Atlas Mine site. These
options are summarized above and described in detail
below. EPA uses nine criteria to evaluate these clean-
up options and select its preferred alternative. These
criteria are explained in detail on page 9.
ALTERNATIVE 1: NO ACTION
The Superfund program requires that the "No
Action" alternative be evaluated at every site to estab-
lish a baseline for comparison. Under this alternative,
no ctean-up action would be taken, but a regular pro-
gram of site monitoring would be started. This moni-
toring program would include periodic sampling of
surface water and airborne asbestos levels in the Atlas
Mine area, as well as aerial monitoring.
The "No Action" alternative is not protective of
human health and the environment and is not consid-
ered an acceptable option for this site.
ALTERNATIVE 2: ACCESS RESTRICTION
The mines and stockpile areas would be fenced to
rpstnrt arrpts and Drevent disturbance by off road ve-
hicles. Signs would be posted throughout the mine
area to warn of an asbestos hazard. The U.S. Bureau of
Land Management has already undertaken a portion
of this fencing and sign-posting.
This alternative would be protective of human
health for persons attempting to drive vehicles across
the Atlas Mine Area but would not address the prob-
lem of asbestos being eroded from the mine area, trans-
ported to nearby creeks and deposited on the Arroyo
Pasajero.
ALTERNATIVE 3: STREAM DIVERSION/SEDI-
MENT RETENTION DAMS; ACCESS RESTRIC-
TION; REVEGETATION
EPA'S PREFERRED CLEAN-UP PLAN
In addition to the access restriction described in Alterna-
tive Z, surface waters would be diverted around contami-
nated soils with perimeter dikes and lined diversion ditches
(see figure3). These stream diversions would minimize ero-
sion of the mine surfaces and tailings piles. Sediment reten-
tion dams would be built to reduce the transport of sedi-
ments. Minor regrading would improve the surface Jrjirt-
age and stability of the mines and stockpile areas The* je-
ttons would minimize the release of asbestos from the Ar/js
Mine into local creeks. The road through the Atlas Mine
Area xvould be paved to reduce airborne asbe
-------
A pilot study would evaluate if
native vegetation could be established
on the disturbed areas without having
to import large quantities of top soil. A
revegetiition project will be implemented
if it is found to be technically feastble.
This alternative provides the best
balance of tradeoffs among the alterna-
tives with respect to the nine criteria
that EPA uses to evaluate clean-up
option5 This alternative would reduce
public hnlth risks by minimizing human
contact with the asbestos and minimiz-
ing the release of asbestos from the
Atlas Mine area. This plan would
reduce health risks more quickly and
cost- effectively than any other alterna-
tive.
ALTERNATIVE 4: REGRADING
OF WASTE PILES PLUS
ALTERNATIVE 3
In addition to all elements of
Alternative 3, Alternative 4 adds
major improvements to the stabil-
ity and drainage of mines and stock-
pile areas. Fully engineered, com-
prehensive improvements would
be performed to minimize collapse
and erosion due to run-off. This al-
ternative would disturb the protec-
tive crust that has formed on the
mine surfaces. It would also be sig-
nificantly more expensive than Al-
ternative 3 without providing meas-
urable improvement in effective-
ness.
ALTERNATIVES: VEGETATi
SOIL CAP; ACCESS RESTRK
HON; STREAM DIVERSION
[ri addition to the stream div
sion element of Alternative 3,
temative 5 includes the constr
tion of a vegetated soil cover
mine surfaces and stockpiles. T
vegetated soil cap would be ci
structed by first reshaping the sto
piles and then covering the mix
and stockpiles with 6 to 12 inches
fertile soil cover. (The revegetab
proposal in Alternative 3 does r
include this soil cover.) Vegetab
would them be established on t
soil cover. To import the amount
fertile soil needed to cover the mi
area would be prohibitively exp«
sive.
ALTERNATIVE 6: CHEMICAL
FIXATION; ACCESS RESTRIC
TION; STREAM DIVERSION
Three million cubic yards
asbestos waste materials would i
chemically fixed with cementii
agents. The asbestos material wou
be excavated from the mine an
and transported to an on- site bate
mixing plant. At the plant, t)
asbestos would be mixed wi1
cementing agents and water to for
a slurry. This slurry would them I
taken to the open pit mines ar
previously excavated area. T1
slurry would harden into a fixe
mass similar to concrete. Strea:
run-off would be diverted arour
areas containing fixed materia
thereby reducing erosion.
This is the only alternative th.
would physically change the asbe
tos waste at the site, but it is consic
ered too costly considering the a<
diticmal protection to human healt
and the environment that woul
result.
ALTERNATIVE 7 OFF SITE
DISPOSAL
Three million cubic vards c
STREAM
//
STREAM
DIVERSION
CHAMCL3
SEDIMEMT
TRAPPMQ
0AM
Figure 3
Overhead View of Stream Diversion
Channels/Sediment Trapping Dam
Tho diversion of streams around asbestos-laden waste piles would reduce the
amouitt of asbestos being transported from the mine area In addition, settling
basinn would collect asbestos-bearing sednnents thereby slowing the trans-
port oi asbestos from the mine area	

-------
would be excavated and transported to an off-site
landfill designed to hold asbestos waste. Nearly all
contaminants would be excavated and the need for
long term monitoring and maintenance of the mines
and stockpile areas would be eliminated.
In addition to being prohibitively expensive, there
would be risks associated with transport of asbestos
from the mine area.
ALTERNATIVE 8: CONSTRUCTION OF A OAM
ON WHITE CREEK
A dam with an approximate reservoir capacity of
7500 acre- feet and an aerial extent of about 200 acres
would be constructed. It would most likely be located
just below the intersection of White Creek and Diaz
Canyon, approximately seven miles down from the
Atlas Mine area. This dam would address the trans-
port of waterbome asbestos from the entire White
Creek watershed, however, this alternative would not
address the health threats at the Atlas Mine.
Altvrmativi
LoMO-Tmi
Efwctiviiiim
& PntMANiMei
Rbducu Toxicity,
Mowuty, Vouimi
(TMV)
OviMU
PHWTICTIOW
Coer
(Pmmmt Wonttm)
Months to
Implement
1
No Action
Not a permanent
solution
No reduction in
TMV
No Protection
$630,000'
3
2
Restnct
Access to
Atlas site
Not a permanent
solution
No reduction
Limited
Protection
$560,000
2
3.
Minimally
intrusive Im-
provements
Not a permanent
solution
No reduction
Adequate
Protection
*44)00400
4

to site drain-
age and sta*

EPA'S PREFERRED CLEAN-UP PLAN



bility






4
Comprehen-
sive improve-
ments to site
drainage and
stability
Not a permanent
solution
No reduction
Adequate
Protection
$ 9.400,000
6
5
Vegetated soil
cap
Not a permanent
solution
No reduction
Adequate
Protection
$ 15,000,000
6
6
Complete
chemical
fixation of site
wastes
Virtually
permanent

Reduces toxicity
and mobility
Most
Protection
$ 103,000,000
48
7
Removal of
site wastes to
oH-site Class 1
Landfill
Permanent
solution

No reduction
Most
Protection
$ 243,000,000
120
8
White Creek
Oam
Does not address
problem at Atlas
Mine
No reduction
Limited
Protection
$ 16,500,000
unknown
* This cost raprtsonts th* cost o» monitoring AhmiKu 2-6 do not Induda th» cost of mentoring
Comparison of Clean-Up Alternatives

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Atlas Mbestos Mine Site
Mining Waste NPL Site Summary Report
Reference 4
Excerpts From Record of Decision,
Atlas Mine Area Operable Unit of the Atlas Asbestos Mine NPL Site;
EPA Region IX; February 14, 1991

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ATLAS MINE AREA OPERABLE UNIT
OF THE
ATLAS ASBESTOS MINE NPL SITE
RECORD OF DECISION
—m—
U.S. Environmental Protection Agency
Region IX - San Francisco, California
February 14,1991

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February 14, 1991
Asbestos is a hazardous substance as defined in 42 U.S.C. Section
9601(14) and as listed in 40 C.F.R. Section 302.4. Asbestos min-
ing and milling waste is not regulated by the Resource Conserva-
tion 
-------
February 14, 1991
RECORD OF DECISION
DECISION SUMMARY
1.0 SITE NAME. LOCATION. AND DESCRIPTION
The Atlas Asbestos Mine Site ("Atlas Site") includes four
geographically distinct areas: i) the Atlas Mine Area ("Mine
Area"); ii) the Clear Creek Management Area ("COMA"); iii) the
Ponding Basin of the California Aqueduct near Gale Avenue
("Ponding Basin"); and iv) the City of Coalinga, California.
This Record of Decision describes the remedy selected for the At-
las Mine Area.
Tfte Ati^s yi,ne
The Atlas Mine Area is an approximately 1.8 square kilometer (450
acre) tract of land located in the southern Diablo Mountains in
western Fresno County, California, on land owned by the Federal
Government and private parties (see Figure 2) . The nearest
population center is Coalinga (population 8250) located ap-
proximately 29 kilometers (18 miles) to the southeast. The Mine
Area includes three open pit asbestos mine surfaces, stockpiles
of asbestos waste material, an abandoned mill building, a set-
tling pond and debris. It is drained by a number of intermittent
streams (see Figure 1) . Lands adjacent to the Mine Area are
rural. Land uses include mining, ranching, farming and recrea-
tion (camping, hunting, hiking, mineral collecting and riding
off-highway vehicles ("OHVs")).
The Clear Creek Management Area
The Atlas Mine Area lies within approximately 124 square
kilometers (48 square miles) of serpentine rock (the New Idria
Formation) containing large amounts of naturally occurring
chrysotile asbestos ("asbestos") as well as other minerals as-
sociated with serpentine. Approximately 93 square kilometers (36
square miles) of the New Idria Formation is within the United
States Department of Interior, Bureau of Land Management's
("BLM's") Clear Creek Management Area and has been designated a
'Hazardous Asbestos Area' by the BUI (see Figure 2). This Haz-
ardous Asbestos Area has been mined for mercury, chromite, asbes-
tos and other minerals since the mid-1800's and contains numerous
mines and exploration cuts as well as innumerable roads and
trails. It is also a popular OHV recreation area. The Hazardous
Asbestos Area of the CCHA has been included as part of the Atlas
Asbestos Mine Site because asbestos mining and milling waste from
the Atlas Mine OU has been transported throughout the CCMA by
wind, water and vehicular traffic.

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February 14, 1991
Atlas Mine OU occurred from 1967 to 1979. The Vinnell Mining and
Minerals Corporation, in a joint venture with California Minerals
Corpsration, owned and operated the mining and milling operation
from 1967 until 1974, when they sold it to Wheeler Properties.
Wheeler Properties operated the facility until 1979 and filed
for bankruptcy shortly thereafter.
The mining activity included digging the asbestos ore out of sur-
face pits and then milling the ore. The by-products of the mill-
ing process (the mill tailings) were bulldozed into piles near
the mill building. Approximately 2.3 million cubic meters (3
mi11:.on cubic yards) of asbestos ore and asbestos tailings remain
at the Atlas Mine OU.
On December 3, 1976 and on February 15, 1980, Atlas Asbestos Com-
pany and Wheeler Properties were cited for violating the National
Emissions Standards for Hazardous Air Pollutants ("NESHAPs")
regulations regarding control of asbestos emissions.
In early 1980, the Metropolitan Water District ("MWD") of
Southern California detected elevated levels of asbestos in water
samples from the California Aqueduct near Los Angeles. An exten-
sive sampling program along the Aqueduct, conducted by the MWD in
August through September of 1980, suggested that the Atlas Mine
was cne probable source of asbestos in the California Aqueduct.
Asbestos levels of up to 2500 million fibers per liter ("MFL")
were measured.
On October 17, 1980, the Central Valley Regional Water Quality
control Board ("CVRWOCB") and the California Department of Health
Services ("DHS") inspected the Atlas Mine to determine if waste
discharges from these facilities were in compliance with state
regulations. The CVRWQCB concluded that additional corrective
measures should be taken to prevent mine- and mi 11-generated as-
bestos from entering the drainage basins.
In March of 1983, the CVRWQCB collected four surface water
samplos during a period of high run-off in the Arroyo Pasajero
watershed. Asbestos fiber concentrations in these samples ranged
from 110,000 to 240,000 MFL.
On June 14, 1983, the risks represented by the Atlas Mine Area
were rated using the Hazard Ranking System. The Atlas Site was
approved for listing on the NPL in September of 1984. Remedial
Investigation/Feasibility Study ("RI/FS") activities were in-
itiated by the United States Environmental Protection Agency
("EPA*') in 1985.
The A':las Minerals Division of the Atlas Corporation, Vinnell
Mininci and Minerals Corporation, Wheeler Properties Inc., the
California Mineral Corporation and the U.S. Bureau of Land
Management have been identified as Potentially Responsible
3

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February 14, 1991
DWR are considering actions to minimize the generation of
asbestos-laden dust in this area. In 1992 EPA will evaluate
whether USBR/DWR actions are adequate to protect human health and
the environment and will publish a public notice of its deter-
mination. At that time EPA will decide whether further EPA ac-
tion under CERCLA in the Ponding Basin is necessary.
Water in the California Aqueduct contains high levels of dis-
persed asbestos fibers. This water is used to supply
municipalities with drinking water and farmers with water for
agricultural purposes such as irrigation. Municipalities are re-
quired to treat drinking water to remove asbestos under the Safe
Drinking Water Act. EPA recommends that the California Depart-
ment of Health Services ("DHS") and the DWR evaluate the poten-
tial, long-term public health effect of delivering asbestos-laden
irrigation water to agricultural areas of the Central Valley.
The Region: The problem of asbestos contamination at the Atlas
Site is part of a larger, regional problem in the New Idria For-
mation, where many other mines and disturbances related to
mineral exploration exist. EPA conducted a regional assessment,
titled Characterization of Disturbances Related to Mining and Ex-
ploration in the New Idria/Coalinqa/Table Mountain Study Region.
EPA intends to address this regional problem in the future.
5.0 SITE CHARACTERISTICS
Figure 3 shows the location of the Atlas Mine Area within the Los
Gatos Creek watershed. The Atlas Mine Area is situated on ap-
proximately 200 hectares (450 acres) in the southern Diablo Moun-
tains, at elevations of 1220 to 1340 meters (4000 to 4400 feet).
The terrain is rugged with slopes ranging from five to 65 percent
and averaging 10 to 15 percent. The tailings and ore piles at
the Atlas Mine OU contain an estimated 2.3 million cubic meters
(3 million cubic yards) of highly concentrated asbestos. The
remedial investigation included analyses of soil, air and water
at the Atlas Mine Area and in the surrounding area:
Soil: The detailed soil sampling in the Mine Area found large
amounts of highly concentrated asbestos. Polarized Light Micros-
copy ("PLM") analyses faee Interim Method for the Determination
of Asbestos in Bulk Insulation Samples. EPA-600/M4-82-020)
detected asbestos concentrations up to four area percent. When
the more sensitive Transmission Electron Microscopy ("TEM")
method was used, the asbestos levels ranged from three percent to
100%. (See Appendix 1 for a discussion of asbestos analytical
techniques).
Water: Water samples taken near the Atlas Mine Area were
measured for asbestos using TEM. Asbestos concentrations were
extremely high, ranging from 3*10® to 2*10® MFL (3 million to 200
million MFL). Surface water transport modeling shoved that
6

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February 1<., 1991
during heavy rains, between five (5) percent and 36% of the total
asbestos yield from the Los Gatos Creek watershed is contributed
by th€i Atlas Mine OU.
Air; Regional air monitoring was conducted in the winter and
summer of 1986 and 1987. Air monitoring stations were located
upwind and downwind of the Atlas Mine OU as well as in Coalinga
and thirteen other locations in the greater Coalinga area. Air
monitoring samples were analyzed using TEM. The data showed that
airborne asbestos concentrations were elevated in the Atlas Mine
OU and throughout the Los Gatos Drainage Basin and parts of the
Arroyo Pasajero Alluvial Fan compared to other areas of Califor-
nia.
winds: Winds that exceed the threshold velocity and activities
that disturb the mine surfaces and tailings piles, such as driv-
ing a vehicle on the tailings piles, can cause airborne asbestos
emissions. Over time, a protective crust has formed on the tail-
ings {dies that appears to reduce wind erosion if left undis-
turbed .
6.0 SUMMARY OF SITE RISKS
The Public Health Evaluation: The following discussion of site
risk summarizes results of a risk assessment conducted as part of
the remedial investigation. The complete risk assessment or
public health evaluation ("PHE") is included as Chapter 6 of the
RI. Because of certain similarities between the Atlas Mine OU and
the JM Kill OU with respect to the contaminant and the media of
concern, EPA prepared one PHE for both sites. However, where
possible, the excess cancer risk due to each Operable Units' in-
dividual contribution of asbestos was calculated separately.
Asbestos - Primary Contaminant: Asbestos is the primary con-
taminant of concern at the Atlas Mine OU, in the CCMA, in the
Ponding Basin and at the City of Coalinga OU. Asbestos is a
generic term referring to two groups of naturally-occurring
hydratad silicate minerals having a fibrous crystalline struc-
ture, i;he amphiboles and the serpentines. The asbestos found in
the New Idria Formation is the serpentine mineral chrysotile.
Asbestos fibers have been widely used for their high tensile
strength and flexibility and for their noncombustible, noncon-
ducting, and cheaical-resistant properties. The fibers have been
used in insulation, brake linings, floor tile, plastics, cement
pipe, paper products, textiles, and building products.
Asbestos - Health Effects: Asbestos is a human carcinogen for
which no level of exposure is believed to be safe. Asbestos has
been the subject of numerous epidemiology studies and exposure to
asbestos has been positively linked to lung cancer, mesothelioma
and asbestosis. Also associated with asbestos exposure in some
studies are cancers of the larynx, pharynx, gastrointestinal
7

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February 14, 1991
tract, kidney, and ovary, as well as respiratory diseases such as
pneumonia.
The adverse human health effects from exposure to asbestos are
extremely serious. A full discussion of the health effects of
asbestos is found in the EPA document Airborne Asbestos Health
Assessment Update. June 1986. Remedial action is warranted to
mitigate the exposure to a carcinogen that is present as a result
of human activity. Actual or threatened releases of hazardous
substances from this OU may present an imminent and substantial
endangerment to public health, welfare, or the environment.
Asbestos - Sources at the OU: Major sources of asbestos at the
Atlas Mine OU are contaminated soils, raw asbestos ore, asbestos
mine and mill tailings and unpaved roads and trails. The three
media of concern at the Atlas Mine Site are air, surface water
and soil. Asbestos is not soluble in water and is not trans-
mitted to ground water.
Routes of Exposure: There are two general routes of exposure to
asbestos at the Atlas Mine OU: inhalation and ingestion. In-
halation is the exposure pathway of greatest concern to human
health because this pathway has been positively linked to cancer
in humans. While not confirmed, there has been one animal study
which suggested that ingestion exposure to asbestos may also be
associated with an increased risk of cancer.
Populations at Risk: Potentially exposed populations include the
following groups: i) individuals who use the Atlas Mine Area
and other areas in the CCMA for recreational OHV driving, hiking,
camping, hunting, ranching and other public uses; ii) individuals
who live in close proximity to the Atlas Mine Area and the CCMA;
and iii) the populations of communities in Fresno and San Benito
Counties such as Huron, Coalinga, Idria, Five Points, Stratford,
Kettleman city, Priest Valley, Lonoak, Panoche and Avenal.
Regional Sources of Asbestos: In the greater Hew Idria-Coalinga
study region, a wide variety of potential regional sources of as-
bestos may contribute to asbestos concentrations in the air.
These regional sources include other mines and disturbed areas in
the CCMA, unpaved roads and trails in the CCMA and naturally oc-
curring serpentinite soils in the New Idria Formation. The risk
assessment evaluated exposure to ambient levels of asbestos due
to all potential regional sources and also to asbestos present in
the air due to the Atlas Mine OU alone.
It is extremely difficult to directly measure the individual con-
tribution of asbestos emissions from the Atlas Mine OU to ambient
air monitoring results because of the other nearby sources in the
New Idria Formation. Therefore, models were used to estimate the
concentration of asbestos in air which would exist if the only
sources of asbestos in the region were wind erosion of tailings
8

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February 14, 1991
piles and mine surfaces and vehicle traffic on unpaved roads run-
ning through the Atlas Mine Area. The air monitoring data were
used in conjunction with historical Total Suspended Particulate
("T.3P") data to obtain annual average air concentrations in
various locations with all sources considered. The TSP data ac-
count for tine periods when the threshold wind velocity for
entrainment was exceeded. Section 5.2.1 of the RI provides a
more detailed discussion of the air modeling methods.
Risl: Assessment Methodology: Excess lifetime cancer risks are
determined by multiplying the intake level with the cancer
potency factor. These risks are probabilities that are generally
expressed in scientific notation (e.g., 1*10~°). In this risk
assessment, an excess lifetime cancer risk of 1*10~6 indicates
that, as a plausible upper bound, an individual has a one in one
million chance of dying from cancer as a result of site-related
exposure to a carcinogen over a 70-year lifetime under specific
exposure conditions.
Inhalation Risk: The highest risk posed by the Atlas Mine OU is
correlated with activity-related exposure, such as exposure due
to cisturbance by motorized vehicles of asbestos-bearing sur-
faces. This exposure could either occur at the Atlas Mine OU or
in .ireas to which asbestos from the Mine Area has been
transported. Exposure point concentrations were calculated using
concentrations of asbestos in soils, sine surfaces and mine tail-
ings in conjunction with estimated emission rates and an air dis-
persion model. Emissions of asbestos-contaminated dust generated
by off-road vehicle activities and by agricultural tilling were
estinated using equations presented in EPA's Compilation of Air
Pollutant Emission Factors for Stationary Point and Area Sources
(EPA, 1985c).
The air dispersion model was a simple box model which defines a
certsiin volume of air (the box) in which emissions from the area
sources are present. The box model assumes that wind speed and
direction are constant within the box and that the air is
unifcrmly mixed. For exposure to ambient air at the Atlas Mine
Area, it was assumed that a 20-year-old-male will be present for
8 hours per day, 52 days per year, for 10 years, to yield an
average continuous exposure duration of 0.47 years (the average
case). For exposure to air during off-road vehicle activity, it
was assumed that a 20-year old male drives for three hours per
day, 16 days per year for five years (the average case). Table 1
summarizes the average and reasonable maximum ("maximum") ex-
posure assumptions use for the various activity related ex-
posures. For both types of activity, the EPA unit risk factor of
.21386 (PCM fibers/cubic centimeter)1.0E-1 was used. There are
data from measurements made in the CCMA by investigators inde-
pendent of EPA, that confirm EPA's estimates of airborne asbestos
concentration made using the air dispersion model, see Ad-
ministrative Record Document Mo. 1612. Users of OHVs on serpen-
9

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February 14, 1991
tinite soils may experience exposure levels that are associated
with an extremely high cancer risk.
Experiments conducted by the California Department of Health
Services ("DHS") in 1985 clearly show that a pickup truck driving
on unpaved asbestos contaminated soil can produce asbestos dust
concentrations in the air that pose a potential health risk to
individuals close to the activity. A discussion of this experi-
ment has been incorporated into the Administrative Record for the
Atlas Mine OU.
The estimated excess lifetime cancer risk for individuals hiking,
camping or hunting at or nearby the Atlas Mine OU varied from
1*10~6 to 3*10 under average and reasonable maximum exposure
conditions, respectively. The estimated excess lifetime cancer
risk for individuals driving a four-wheel-drive truck on the At-
las Mine OU varied from 5*10"* to 4*10-1 under average and
reasonable maximum exposure conditions, respectively.
ingestion Risk: The excess lifetime cancer risk from drinking
asbestos contributed to the water from the California Aqueduct by
the Atlas Mine OU was not found to be significant. The risk es-
timates were calculated assuming ingestion of two liters of water
per day for a 70 year period by an adult weighing 70 kilograms
(154 pounds). EPA's unit risk factor of l.4*io"^-3
(fibers/liter)-1 was used (CPA, 1985b).
The estimated excess lifetime cancer risk for individuals ingest-
ing untreated California Aqueduct water, contaminated with asbes-
tos from all sources in the Los Gatos Creek Drainage Basin (not
just the Atlas Mine OU) , varied from 2*10"° to 4*10"^ under
average and reasonable maximum exposure conditions, respectively.
However, it should be noted that municipalities are required to
filter drinking water under the Safe Drinking Hater Act, thereby
reducing exposure to asbestos.
Asbestos Measurement - Uncertainty Concerning Risk Levels; When
evaluating risk from asbestos in the environment, there are
sources of uncertainty associated with asbestos measurement that
make quantifying the risk difficult.
Complexitiee of Particle Measurement; One of these sources of
uncertainty is the difficulty of obtaining accurate and precise
measurements of asbestos concentrations in soil, air, and water.
For example, all risk assessments require an accurate and precise
measurement of contaminant concentration. When a gaseous or
soluble chemical is the contaminant of concern, the measurement
of only one parameter, concentration, is sufficient to establish
how much of that contaminant is present in a given sample.
However it is significantly more complex to measure the con-
centration of particulates accurately and precisely, especially
fibrous particulates, because many more parameters must be ac-
10

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February 1<., 1991
tive, the disturbed areas will be reclaimed with vegetation to
the e>:tent found to be appropriate.
Road Pavina or an Engineered Alternative. Mill Dismantling. Dis-
posal of Debris and Deed Restrictions: The road through the Mine
Area trill be paved or an alternative vill be adopted to suppress
dust. The mill building vill be dismantled and disposed of along
with other debris in the Mine Area. A deed restriction will
limit use of the privately held land and prevent disturbance of
the contaminated material left at the Mine Area OU.
Operation and Maintenance: Visual inspections, both on the
ground and from the air, will be required to ensure the integrity
of th« engineering and institutional controls. Operation and
maintenance activities will be required to ensure the effective-
ness of the engineering controls. These activities will include:
(1) inspection of engineering systems to ensure integrity and
performance, (2) removal of sediments from retention dams, (3)
any repair work necessary to maintain the integrity of the
remedial systems, (4) maintenance of the vegetation, and (5)
regular policing of the Atlas Mine Area by BIX rangers.
Five Year Review: EPA will review the effectiveness of the
remedial actions pursuant to CERCLA Section 121(c), 42 U.S.C.
Section 9621(c).
cost; Using a conservative estimate, the total capital cost for
the selected alternative is $4 million. Annual operation and
maintenance activities are estimated at $19,000. The total
present worth cost for the selected remedy is estimated to be
$4,286,000. Table 2 summarizes costs for the selected alterna-
tive.
During the remedial design and construction process, that follows
this ROD, some changes to the selected remedy may be required and
will be made in accordance with the NOP. CERCLA Section 117, 42
U.S.C. Section 9617 and 40 C.F.R. Section 300.435(c)(2).
11.0 DOCUMENTATT ON of SIGNIFICANT CHANGES
The seLected alternative for the Atlas Mine OU is construction of
engineering systems to control the release of airborne and water-
borne asbestos from the Atlas Mine Area and accompanying
measures, as detailed in Section 10, above. At this time no sig-
nificant changes from the Proposed Plan have occurred. Minor
changes are described in Section 7.0.
12.0 .'STATUTORY DETERMINATIONS
overall Protection of Human Health and the Environment
The selected remedy protects human health and the environment by
minimi ting exposure to asbestos-contaminated materials. Proper
24

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Mining Waste NPL Site Summary Report
Bunker Hill Mining and Metallurgical Complex
Kellogg, Idaho
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-0025, Work Assignment Number 20.
A previous draft of this report was reviewed by Sally Martin of EPA
Region X [(206) 553-2102], the former Remedial Project Manager for
the site, whose comments have been incorporated into the report. The
present Remedial Project Manager for the site is John Meyer [(206)
553-1271].

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Mining Waste NPL Site Summary Report
BUNKER HILL MINING AND METALLURGICAL COMPLEX
KELLOGG, IDAHO
INTRODUCTION
This Site Summary Report for the Bunker Hill Mining and Metallurgical Complex is one of a series
of reports on mining sites on the National Priorities List (NPL). The reports have been prepared to
support EPA's mining program activities. In general, these reports summarize types of environmental
damages and associated mining waste management practices at sites on (or proposed for) the NPL as
of February 11, 1991 (56 Federal Register 5598). The summary report is based on information
obtained from EPA files and reports and on a review of the summary by the former EPA Region X
Remedial Project Manager for the site, Sally Martin.
SITE OVERVIEW
The Blinker Hill Superfiind Site is one of the largest and most complex Superfund sites in the Nation.
The site is located in the Silver Valley of the South Fork of the Coeur d'Alene River of Northern
Idaho. It is approximately 60 miles east of Spokane, Washington. Bounded on the west by the Town
of Pimhurst and on the east by the Town of Kellogg in Shoshone County, Idaho, the site is 3 miles
wide and 7 miles long and bisected by Interstate 90 (Reference 1, page 1-1) (See Figure 1) (Reference
1, page ES-3).
The site is centered on the Bunker Hill mining complex, which consists of an inactive integrated
mining , milling, and smelting operation (see Figure 2). The complex includes the Bunker Hill Mine
Qead and zinc), a milling and concentrating operation, a lead smelter, a silver refinery, an electrolytic
zinc plant, a phosphoric acid and phosphate fertilizer plant, sulfuric acid plants, and a cadmium plant
(Reference 1, pages 1-1 and 1-4).
Also included within the site boundary are the Page Mine (inactive), the Page tailings disposal area
knowr, as "Page Ponds." (currently the site of Silver Valley water treatment facility), and numerous
old mines, mill sites, and prospects. The site includes the communities of incorporated cities of
Wardner, Kellogg, Smelterville, and Pinehurst, with a total population of 5,000 as of August 1990.
1-

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Bunker Hill Mining and Metallurgical Complex
FIGURE 1. PROJECT AREA MAP

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Mining Waste NPL Site Summary Report
FIGURE 2. BUNKER HILL MAP

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Bunker Hill Mining and Metallurgical Complex
The major environmental problems at the site were caused by smelter operations and mining and
milling. During smelter operations (1917-1981) wastes and feed stock were stored onsite. In
addition, the smelter discharged heavy metal particulates and sulphur dioxide gas to the atmosphere.
Milling operations discharged tailings directly into the South Fork of the Coeur d'Alene River and its
tributaries, until the first tailings impoundment was constructed in the 1920's. Decant from this
tailings impoundment was discharged directly to the South Fork. Mine drainage was also discharged
to the River.
Contaminants of concern are lead, zinc, cadmium, antimony, arsenic, beryllium, copper, mercury,
Polychlorinated Biphenyls (PCBs), selenium, silver, cobalt, and asbestos. Lead, zinc, and cadmium
are given most attention due to their pervasiveness or acute toxicity (Reference 1, page 1-6).
The lead and zinc plant stacks used baghouses to capture particulates; however, a 1973 fire damaged
the baghouse filtration system, allowing an increase in particulate emissions. Two of seven baghouses
were incinerated and the remaining five were shut down for 6 months to be repaired (Reference 1,
pages 2-93, 2-102, and 2-103).
Health effects were first documented following the extreme smelter emissions in 1973 and 1974.
Median blood levels for area children aged 9 or younger were 46 (micrograms per jig/dl) in 1974. In
1974, more than 98 percent of 172 children living within 1 mile of the smelter had always "blood
lead" levels exceeding 40 fig/d] (Reference 5, page 1-19; Reference 1, page ES-31). These levels are
in excess of the current Center for Disease Control (CDC) criteria of 25 jug/dl. According to the
World Health Organization, the no-detected effect level for blood lead is about 10 jig/dl and "may be
even lower" (Reference 5, page 1-19; Reference 1, pages ES-16 and ES-31). Children in residential
areas nearest the smelter have shown the greatest blood lead levels. In 1983, 25 percent of preschool
children in the most contaminated area exhibited lead blood levels greater than 25 /tg/dl. Since 1983,
mean blood levels in children have continued to decrease. Median blood levels for area children aged
9 or younger were 8 jig/dl in 1990; less than 5 percent showed levels over 25 /xg/dl (Reference 5,
pages 1-19 through 1-21).
In 1986, EPA removed contaminated soils from 16 parks, playgrounds, and road shoulders. In 1989
and 1990, contaminated soil was removed from residential yards; yards chosen for the program had
lead levels of 1,000 parts per million (ppm) or greater and were residences of small children or
expectant mothers (Reference 2, page 2).
Ecological damage surrounding the site has also occurred. The hillsides around the smelter complex
are denuded of vegetation due, in part, to the smelter emissions and mining activity. The Bunker Hill
4-

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Mining Waste NPL Site Summary Report
Company, as part of a re-vegetation effort beginning in the early 1970's, identified about 14,400
acres th.it had been damaged by smelter emissions or mining. Although re-forestation efforts have
been conducted, much of the project area remains sparsely vegetated (Reference 1, page 2-80).
In 1989, EPA ordered two of the Potentially Responsible Parties (PRPs) to remove and contain
hazardous substances and halt demolition and salvage operations at the smelter complex. As a result
of the order, fencing was installed around the smelter complex, a sealant was applied to a copper
dross flue dust pile, and a substantial amount of asbestos was removed (Reference 2, page 1).
Because the Remedial Investigation/Feasibility Study has not been completed at this time, final
corrective actions and costs have not been determined. However, the EPA Remedial Project Manager
stated that a cost estimate that exceeds $100 million is not unreasonable (Reference 4).
OPERATING history
Lead and zinc mining began on the Bunker Hill site with the location of the Bunker Hill and Sullivan
claims in 1885 by Noah Kellogg (Reference 3, page 35). The first mill began operations in 1886,
near the Reed Tunnel in Milo Gulch in Wardner. A larger mill was constructed in 1891, near the
portal of the present Kellogg Tunnel. Before the Kellogg Tunnel was completed in 1902, ore was
transfeiTed to the mill by aerial tramway. Flotation was first added in 1913 (Reference 3, pages 43
through 45). The lead smelter began operation in 1917. An electrolytic zinc plant, capable of
producing 99.99 percent zinc, began operation in 1928. An electrolytic antimony plant was
constructed in 1939, but it operated only for a few years. In 1943, a slag fuming plant was
constructed to recover zinc from the blast furnace slag of the lead smelter (Reference 3, page 36). A
cadmium recovery plant was added in 1945 (Reference 3, page 51). A sink-float plant operated from
1941 to 1953 (Reference 3, pages 45 and 46). A phosphoric acid plant began operations in 1961.
The pl.uit used sulfuric acid from the zinc plant and phosphate rock from southern Idaho or Wyoming
to produce phosphoric acid and gypsum (Reference 1, page 2-101). Sulfuric acid plants were added
to the tine facilities in 1954 and 1966. The lead smelting process was changed in 1970 from a
downdraft ore-roasting operation to a Lurgi updraft sintering process with a sulfuric acid recovery
plant. In 1976 and 1977, a 715-foot stack was added to the lead smelter, and a 610-foot stack was
added to the zinc plant'(Reference 1, pages 2-90 and 2-91). In December 1981, the smelter complex
was shut down. Parts of the Smelter Complex have been salvaged since closure (Reference 1, pages
2-89 and 2-90).
Originally, all liquid and solid residues were discharged to the South Fork of the Coeur d'Alene and
its tributaries. Periodic floods deposited contaminated wastes onto the valley floor. In 1928, the first
5-

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Bunker Hill Mining and Metallurgical Complex
impoundment at the Central Impoundment Area began operation. Later, the Central Impoundment
Area was used for tailings, gypsum, and mine drainage water. The decant from the this area flowed
directly into the river until 1974, when the Central Treatment Plant was installed (Reference 1, pages
2-91 and 2-92).
The Bunker Hill Company (formerly the Bunker Hill and Sullivan Mining Company) purchased Hecla
Mining Company's interest in the Zinc Plant and the Star Mine, and consolidated the complex under
one ownership in 1955 (Reference 3, page 37). In 1968, the Bunker Hill Company was purchased by
Gulf Resources and Chemical Company. Gulf operated the plant until its closure in December 1981.
In 1982, the complex was sold to Bunker Limited Partnership, its present owners (Reference 1, page
2-89). In 1983, a circuit of the mill and an associated mine offsite were reopened. However, the
mill and mine were shut down due to continuing depressed silver prices in 1986. At this time, active
operations at the complex included the mine pumps, a wastewater treatment plant, and a zinc
concentrate dryer (under lease to another mining company) (Reference 1, pages 2-89 and 2-90). The
mine and mill were reopened in 1988 when metal prices improved, and closed again in 1991 due to
bankruptcy. The smelter complex remains closed and salvage has started.
SITE CHARACTERIZATION
The site was listed on the NPL in September 1983, at which time the Remedial Investigation/
Feasibility Study process was initiated to characterize and determine the extent of contamination in the
area affected by the mining and smelting operations. Initially, all liquid and solid residues from
mining and milling operations were discharged into the South Fork and its tributaries. The river
flooded and deposited mining waste material or tailings onto the valley floor periodically. Ground
and surface waters have since been contaminated by leaching of tailings.
In the 1920's, mill tailings were discharged to a small impoundment, and lead smelter slag was placed
in what became the slag pile. Late tailings in the first impoundment were reprocessed and tailings
were deposited in the Central Impoundment Area (CIA). After 1961, the coarse fraction of mill
tailings were used as sand backfill in the Bunker Hill mine. The CIA also received mine drainage
beginning in 1965, gypsum from the phosphoric acid and fertilizer plant after 1970; and wastes from
the zinc plant and smelter after 1974. Decant from the CIA was discharged directly to the River until
1974, when the Central Treatment Plant became operational; after 1974, decant from the gypsum
discharge was returned to the phosphate plant (Reference 1, pages 2-90 and 2-92).
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Mining Waste NPL Site Summary Report
In addition, emissions from the lead and zinc plant stack (until 1981), and fugitive dust from various
areas on the site before and after that time, particularly from the CIA, have contaminated air and soils
with ha ivy metals (Reference 1, pages ES-27, ES-28, 2-93, and 2-94).
The types and extent of contamination at the Bunker Hill site are complex. Soils, ground water,
surface water, and air have all been contaminated. A brief characterization of each contaminated
mediurr is presented below.
Soils
Residuiil soil contamination with metals is a major concern at the site. During smelter operation,
metal-luden particulates were discharged from the smelter. Between 1965 and 1981, the lead smelter
main stack emitted in excess of 6,000,000 pounds of lead, 560,000 pounds of cadmium, 860,000
pounds of zinc, and 70,000 pounds of arsenic. These gross estimates do not include vent and fugitive
emissions, which were believed to total more than stack emissions. In addition, wastes and other
metal-contaminated material were placed on the ground or discharged directly to the river, resulting
in concentrated areas of soil contamination (Reference i, pages ES-20 and ES-26).
Soils njar the smelting complex have been severely impacted by sulfur oxide and metals deposition.
Early fires and harvest practices destroyed much of the native vegetation, and air pollution has
preven ed new growth. Erosion has further reduced the ability of the soil to sustain vegetation. In
the top .5 inch of soil, lead concentrations in the hillside soil (in 1974) ranged from 1,000 to 24,000
ppm and cadmium concentrations ranged from 50 to 236 ppm. On undisturbed areas, most of the
metals were found in the top 3 inches, while in severely eroded areas, airborne contamination
penetrated at least the top 10 inches (Reference 1, page ES-5).
In general, "most of the area within the property area boundaries must be regarded as significantly
contaminated." Around the smelter complex itself, extremely high concentrations of lead (1,000 to
40,000 ppm) and cadmium (80 to 240 ppm) were detected. Heavy contamination extends over the
City of Smelterville with concentrations exceeding 5,000 ppm (Reference 1, page ES-21).
The upper 10 to 20 feet of soils on the valley floor are combined with mine and mill tailings and rock
dust generated by the minerals processing industry in the early part of the century. Early milling
practic es resulted in the deposition of metals-rich tailings to low-lying areas. Lead and cadmium
levels are similar to those in the hillside soils (Reference 1, pages ES-5, 2-11, and 2-12).
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Bunker Hill Mining and Metallurgical Complex
The Smelterville Flats encompass an area of approximately 2 square miles north and west of the City
of Smelterville, where significant amounts of unconfined tailings have accumulated over this century.
Surface metal concentrations ranged from 6,000 to 25,000 ppm lead, and 30 to 70 ppm of cadmium
(Reference 1, page 2-13).
The Page Ponds and the Central Impoundment Area cover 240 acres and contain several million cubic
yards of tailings. These areas are located close to major residential areas and have lead
concentrations from 2,000 to 20,000 ppm (1974 and 1977 studies) (Reference 1, pages 2-13 and
2-14).
Surface Water
The Bunker Hill site is situated in the Coeur d'Alene River basin. The South Fork of the River and
its tributaries are shown in Figure 3. Below Wallace (shown on Figure 3), the South Fork is a
relatively shallow and swiftly flowing stream with a gradient of about 30 feet per mile. The streams
in the vicinity of past mining activities have received a heavy sediment load of mine and mill tailings.
The sediment load to the South Fork is much larger than the river's transport ability. This has caused
significant filling of the main channel; in some of the wider flood plain areas, the River has become a
meandering stream with braided channels (Reference 1, page 2-24). The South Fork flows west to
Enaville, through Smelterville, Kellogg, Silverton, and Wallace (Reference 1, pages 2-21 through
2-23).
Other surface-water features at the Bunker Hill Complex include the Central Impoundment Area,
which includes the central impoundment pond, the gypsum pond, and the slag pile. Other smaller
impoundment areas are located near both the lead and zinc smelter, including Sweeney Pond and the
main reservoir in the lead smelter complex, and the main reservoir and settling ponds in the zinc plant
area. Major streams on the complex include Government Creek and Bunker Creek; Mile Creek
borders the complex to the east. Many intermittent streams feed these Creeks (Reference 1, pages 2-
32 to 2-34).
The South Fork of Coeur d'Alene River has been receiving mine and mill wastes for approximately
90 years. The sources'of pollution include direct discharge of acid mine drainage to the river by
Bunker Hill operators (until 1965); direct discharge of lead smelter and zinc plant wastes (until 1974),
direct discharge of Central Impoundment Area and gypsum pond water to the River (until 1974);
seepage from the Central Impoundment Area; numerous accidental spills of contaminants into
tributaries of the South Fork; and contaminated overland flow from heavy metals deposited from
airborne emissions (Reference 1, page ES-23).
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Mining Waste NPL Site Summary Report
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FIGURE 3. SCHEMATIC MAP OF THE SOUTH FORK COEUR D'ALENE RIVER
AND ITS TRIBUTARIES
9

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Bunker Hill Mining and Metallurgical Complex
To assess the change in water quality of the South Fork of the Coeur d'Alene River and its tributaries
(over time) various researchers have taken water-quality measurements sporadically between 1966 and
1984. These measurements and associated drinking water standards are presented in Tables 3-18
through 3-32 in Reference 1. Yearly means and overall averages of the following parameters
are listed in those tables: antimony, arsenic, cadmium, chromium, copper, fluoride, iron, lead,
manganese, mercury, selenium, zinc, pH, hardness, and total sulfates (Reference 1, pages 2-190
through 2-214).
The maximum yearly mean contaminant levels for each contaminant measured at significant
concentrations above EPA drinking water standards in the South Fork since the mid-1960's are
presented in Table 1 below (Reference 1, page ES-23).
TABLE 1. MAXIMUM YEARLY MEAN CONTAMINANT LEVELS IN
THE SOUTH FORK (1966 TO PRESENT)

South Fork
(in jig/1)
EPA Drinking Water
Standards fin pg/1)
Year
Arsenic
144
50
1971
Cadmium
500
10
1979
Chromium
581
50
1971
Fluoride
16
1.4-2.4
1971
Iron
16,000
300
1978
Lead
1,200
50
1971
Manganese
5,758
50
1976
Mercury
250
2
1976
Selenium
10
none
1972
Zinc
79,000
5,000
1972
Since 1966 (when monitoring began), Bunker Hill's contributions of heavy metals to the South Fork
has been reduced significantly during three instances. In 1968, the construction of tailings ponds
were mandated, which trapped most of the suspended materials from the mine and mill wastes. In
1974, wastewater treatment of outflow from tailings ponds was required, and zinc plant and lead
smelter effluents were routed to the CIA. Finally, the Bunker Hill complex was closed down by Gulf
Resources and Chemical Corporation in 1981 (Reference 1, pages ES-23 and ES-24). Discharges still
10

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Mining Waste NPL Site Summary Report
continu; from the site, including, for example, those from the operating wastewater treatment plant.
As of 1984, concentrations of several contaminants were still significant: cadmium (28.6 iigfl), iron
(1,146 ng/1), manganese (1,507 #tg/l), and zinc (3,270 jig/1) (Reference 1, page ES-24).
Concentrations in CIA seepage and in two creeks showed higher concentrations (in some cases).
The cuirent water quality of standing water on the Bunker Hill complex (e.g., the CIA) was not well
known in 1986. However, as stated in the Interim Site Characterization Report, the CIA "contains
very high levels of contaminants and many of the other ponds on the complex may contain hazardous
levels of contaminants." During a site inspection (the date was not given), it was observed that there
are numerous areas where runoff originates from, or passes through, some potentially highly
contaminated areas; that the collection systems are in poor condition; and that many ponds had broken
liners (Reference 1, page ES-24).
Primary sources of surface water contaminants from the site (based on data from 1987-1988) were
identif ed as:
•	Ground-water seeps near the CIA
•	Transient high flows from Government Gulch and Bunker Creek
•	Diffuse ground-water inflows (Reference 7, page 4).
Ground Water
In the eastern portion of the project area (outlined as the site boundary in Figure 1), the South Fork
aquifer appears to be a single unconfined unit of sand and gravel. Above Kellogg, these sediments
are medium- to coarse-grained and contain lenses of sandy silt. Below Kellogg, clayey silt interrupts
the vertical continuity of the sand and gravel fill, which forms an impermeable zone and separates the
alluvium into two well-defined aquifers (unconfined and confined). Whether there is an
interconnection between the confined and unconfined aquifers is unknown. Shallow bedrock may
either terminate the confined aquifer or provide a conduit via fractures for confined flow to recharge
the unconfined aquifer and the River (Reference 1, page 2-46).
Primary sources of ground-water contamination include seepage from the CLA, infiltration and
ground-water flow through valley-wide deposits of tailings, and ground-water inflow upgradient of the
site. Other sources of ground-water contamination include discharges from Magnet Gulch; Pine
Creek, and Milo Gulch, infiltration of incident precipitation through the CIA; and seepage from
11-

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Bunker Hill Mining and Metallurgical Complex
Sweeney Pond, McKinley Pond, and other surface impoundments. Contaminants of primary concern
included arsenic, cadmium, lead, cobalt, and zinc (Reference 7, pages 5 and 6). Seepage from the
CIA is estimated to be 1 cubic foot per second (cfs) (Reference 7, page 9).
Maximum zinc and cadmium levels have been detected in wells adjacent to the CIA at SO and 0.1
milligrams per liter (mg/I), respectively, in a study by Norbeck (1974). These values appear to have
reflected partly diluted direct seepage from the CIA. Hawke Engineers (1978) and Robinson, et al.
(1980) reported high levels of zinc in ground water supposedly derived from the lower-gravel aquifer.
Whether contaminants from the CIA have entered the confined lower aquifer remains unknown.
While studies have been done to evaluate the seepage and metal transport to ground water from the
CIA, they have not specifically targeted the extent and degree of ground water contamination, and
thus, have not determined the spread of contaminants into the ground water beyond the well network
established by the Bunker Hill Co., EPA, and others (Reference 1, pages ES-24, ES-25, and 3-232).
Ground water in the Smelterville Flats area contains high levels of heavy metals, but the
concentrations generally decrease with depth and linear distance from the South Fork. The ground
water appears to be in hydraulic connection with surface ponds in the flats. In 1979, it was estimated
that the flats discharge about 5.3 kilograms (kg) per day of zinc to the ground water (Reference 1,
pages ES-25, 3-233, and 3-234).
The Page ponds discharged about 8 kg per day of zinc to the ground water in 1975. The ponds have
subsequently been converted for sewage treatment. Information on the potential of heavy-metal
contamination of ground water from these ponds remains unavailable (Reference 1, pages ES-25 and
3-234).
Air Emissions and Air Quality
From 1918 to 1981, smelting and refining operations have discharged heavy metal paniculate matter
and gases, particularly sulphur dioxide, into the atmosphere. The first sulfuric acid plant was added
to the zinc plant in 1954 to remove sulphur dioxide from the stack gases. In 1968, a sulfuric acid
plant was added to the lead smelter, and in 1970, it was upgraded (from a downdraft ore-roasting
operation to an updraft sintering process with an associated sulfuric acid recovery plant) (Reference 1,
pages 2-93 and 2-66).
Baghouses have also been used on the lead and zinc plant stacks to recover the heavy metal
particulates that otherwise would be discharged and lost with the stack gases. It is believed that these
were incorporated into the plants in the early 1970's, although the available information was unclear.
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Mining Waste NPL Site Summary Report
In September 1973, a fire severely damaged the baghouse filtration system. Two of seven baghouses
were incinerated and a third was shut down for routine maintenance and was inoperable for 6 months.
During this time, 20 to over 100 tons per month of particulates containing 50 to 70 percent lead were
emitted from the stacks (compared to the normal 10 to 20 tons per month) (Reference 1, pages 2-66,
2-67, a.id 2-93).
Air-qucdity measurements by the State of Idaho (the date was not provided) show a drop off of sulfur
dioxide after 1977 (when tall stacks were installed), and again, after the late 1981 cessation of lead
smelter operations, lead and particulates also declined significantly.
Lead, cadmium, zinc, mercury, and arsenic emissions from the lead smelter main stack were
calculated for the period of 1965 to 1981. In excess of 6 million pounds of lead; 550,000 pounds of
cadmium; 860,000 pounds of zinc; 29,000 pounds of mercury; and 70,000 pounds of arsenic were
emitted during this period. These figures are for the lead smelter main stack and do not include vent
and fugitive emissions, which were believed to total more than stack emissions. According to the
Interim Site Characterization Study, fugitive dust sources are expected to be of greatest concern
regard'ng air contamination since the shutdown of the lead smelter (Reference 1, page ES-26).
Ambient air monitoring has been conducted at the site since 1971.
Since :;melter closure, ambient lead levels and total suspended particulates have generally been within
primaiy National Ambient Air Quality Standards (NAAQS). Ambient lead levels have ranged from
0.1 to 0.5 figlm3 (on a quarterly basis) and ambient levels of total suspended particulates have ranged
from j0 to 70 /tg/m3 (on an annual basis) with daily values ranging to 900 /ig/m3 (Reference 5, page
2-34). The NAAQS for lead is 1.5 /tg/m3 (on a quarterly basis) and the primary NAAQS for
particulate matter is 150 pg/m3 [on a 24-hour basis, for particles under 10 microns (ji)]. It should be
noted that EPA (in 1989) proposed lowering the lead NAAQS to 0.5 ngJm3 (Reference 5, page 3-6).
ENVIRONMENTAL DAMAGE AND RISKS
Much of the data described in reference materials and in this Site Summary Report are for lead, zinc,
and a few other heavy metals. However, as described previously, many more constituents than these
are "found repeatedly at high levels in the Silver Valley, or recorded within the Bunker Hill
complex." These include cadmium, arsenic, PCBs, silver, selenium, copper, beryllium, mercury,
antimony, asbestos, and cobalt. It should be noted that "[documented lead concentrations and body
lead indicators can serve as indicators of the routes of population exposure to contaminants of concern
in general" (Reference 1, pages ES-30 and ES-31).
\y

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Bunker Hill Mining and Metallurgical Complex
Health effects were first documented following the extreme smelter emissions in 1973 and 1974
(Reference 5, page 1-19). In 1974, more than 98 percent of 172 children living within 1 mile of the
smelter had blood lead levels exceeding 40 /xg/dl (Reference 1, page ES-31). Median blood levels for
area children aged 9 or younger were 46 /xg/dl in 1974. The current CDC criteria is 25 /xg/dl
(Reference 5, page 1-19). CDC has noted that a community action level of 10 /zg/dl is being
considered due to recent information that adverse health effects are associated with low blood levels
(Reference 5, page 3-18). The WHO indicates that the blood-lead level for "no-detected effect" is 10
/xg/dl or lower (Reference 1, page ES-16).
Children in residential areas nearest the smelter have shown the highest blood-lead levels. In 1983,
25	percent of preschool children in the most contaminated area exhibited blood-lead levels greater
than 25 /xg/dl. Since 1983, mean blood levels have decreased (Reference 5, pages 1-19 through 1-
21).
A follow-up study by CDC and the State of Idaho surveyed 364 children in 1983. Blood-lead levels
in the children from Smelterville ranged from 6 /xg/dl to 35 /xg/dl with a mean of 21 /zg/dl. These
levels were down from an average of 68 /xg/dl in 1974 and 31 jug/dl in 1980. In a second study area
(Kellogg, Wardner, and Page residences), mean blood-lead levels dropped from 49 /xg/dl in 1974 to
26	/xg/dl in 1980 and to 17 /xg/dl in 1983. Strong correlations were found between children's blood
lead levels and residential-area soil lead levels, household dust lead levels, and (to a lesser extent)
childhood mouthing behavior and other factors (Reference 1, page ES-31).
In 1985, a follow-up survey to the 1983 study was initiated in Kellogg, Smelterville, and Wardner.
This was completed for CDC and involved 348 children under 9 years old. Ten children were
identified as having blood-lead levels exceeding the CDC's limit of 25 /xg/dl, which represented a
significant reduction from the previous studies. However, within this study, the highest blood-lead
level in the area since 1979 was measured at 59 /xg/dl in a 4-year old child, and a 15-month old child
had 51 /xg/dl (Reference 1, page ES-31).
More recently, in 1989, 3 percent of 275 children aged 9 or younger living in Smelterville, Kellogg,
Page, and Wardner exhibited blood-lead levels of 25 /xg/dl or greater, with 56 percent exhibiting
levels of 10 /xg/dl or more. The median was 10 /xg/dl. In 1990, 2 of 255 children from the same
area exhibited blood-lead levels of 25 /xg/dl or more, with 40 percent of the children exhibiting levels
of 10 /xg/dl or more. The median was 8 /xg/dl (Reference 5, page 3-20). Lead is of concern because
it can cause nerve and kidney damage, and young children are especially susceptible (Reference 1,
page ES-16).
14

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Mining Waste NPL Site Summary Report
In 1983, when the Remedial Investigation/Feasibility Study was started, and as a result of the blood-
lead studies, EPA decided to focus on the removal of contaminated soils from public areas in the
populated portions of the site to reduce the lead poisoning in young children.
The pathways for human exposure include household dusts and soils. Locally grown vegetables are
also an exposure pathway; EPA has (through a health intervention program) recommended against
eating them since 1985.
Shown below are concentrations of lead, cadmium, and zinc in 1974 and 1983. As can be seen in
Table 2, concentrations declined substantially over the period but still remained high.
TABLE 2. LEAD, CADMIUM AND ZINC CONCENTRATIONS IN HOUSEHOLD DUST
SOILS

Lead (in ppm)
Cadmium (in ppm)
Zinc (in ppm)

1974
1983
1974
1983
1974
1983
Household dust
11,920
3,994
NA
67
NA
2,840
Soils
7,224
3,504
63
54
2,340
126
Garden lettuce
231
48
28
5
NA
73
NA - not analyzed
In October 1989, an inspection of the smelter complex conducted by the Agency for Toxic Substances
and Disease Registry (ATSDR) resulted in a Public Health Advisory. The advisory concluded that
the snuilter complex was a "significant risk to public health" which may result from: (1) acute
exposure to arsenic from the copper flue dust piles; (2) acute exposure to lead, cadmium, arsenic, and
asbestcs; (3) chronic exposure to lead, cadmium, arsenic, and asbestos during site operations such as
salvaging; and (4) physical hazards. ATSDR recommended that site access be restricted and that all
activities be suspended until site safety plans are approved (Reference 6, page 1).
A soil survey was conducted, in 1986-1987 in the communities of Smelterville, Kellogg, Wardner,
and Page. Samples of the top 1 inch of mineral soil and litter (decaying vegetative matter and sod)
were analyzed from 1,020 of 1,547 homes (64 percent of area homes). Five percent of all homes
sampled had lead levels below 500 jig/g, 11 percent had lead levels between 500 and 1,000 jtg/g, and
84 percent had lead levels above 1,000 jtg/g (Reference 5, pages 2-13, 2-14 and 2-21). The CDR has
15"

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Bunker Hill Mining and Metallurgical Complex
indicated that soil and dust levels over 500 to 1,000 ppm lead may be responsible for increasing
blood-lead levels in children (Reference 5, page 3-2).
Environmental and ecological damage has also occurred. The Bunker Hill Company, as part of a re-
vegetation effort beginning in the early 1970's, identified about 14,400 of 18,000 acres that had been
damaged by smelter emissions or mining (Reference 1, page 2-80). Studies conducted as part of the
Remedial Investigation concluded that site vegetation has been damaged by logging, fires, and
emissions from the lead smelter, zinc plant, and phosphoric acid/fertilizer plant. Closed coniferous
forest has been replaced by open scrub and woodland communities with extensive areas of barren
and/or sparsely vegetated soils. About 1,400 acres had less than 25 percent vegetative cover and
another 1,700 acres had between 25 and 50 percent cover. Re-vegetation of some areas may be
restricted by arsenic and heavy metal concentration (Reference 7, page 8)
There is no year-long resident population of fish inhabiting the river in (or below) the project area to
the confluence of the South Fork and the mainstem of the Coeur d'Alene River. According to the
Site Characterization Report (Reference 1), this is due to the heavy metal concentrations in the South
Fork of the Coeur d'Alene River (Reference 1, page ES-23). For further detail concerning biotic
contamination of heavy metals, refer to Table 3-45 of Reference 1. This table presents heavy metal
concentrations detected at various times between 1931 and 1982 of several organisms within the
Coeur d'Alene River Valley ecosystem (Reference 1, pages 3-263 through 3-267).
REMEDIAL ACTIONS AND COSTS
At the present time, the Bunker Hill Remedial Investigation/Feasibility Study is continuing, and EPA
has not yet determined the final remedial actions and their associated costs. Three remedial actions
have been taken to date:
•	In 1986, contaminated soils were removed from 16 parks and playgrounds and along road
shoulders. EPA has recovered $1.4 million in this action from Gulf Resources (one of the
many PRPs) (Reference 2, page 2)
•	In 1989 and 1990, contaminated soils were removed from approximately 210 residences and 2
large apartment complexes. The soils were removed from homes with high lead levels and
where young children or expectant mothers reside (Reference 5, pages 2-21 and 2-22)
•	In October 1989, EPA issued an order to the PRPs to remove or contain hazardous substances
and halt demolition and salvage operations. As a result of the order, several thousand feet of
fence were installed around the smelter complex; a large material accumulation pile was
16.

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Mining Waste NPL Site Summary Report
covered with dust suppressant; and deteriorating asbestos containing materials were removed
(Reference 2, page 1).
CURRENT STATUS
A Remedial Investigation/Feasibility Study for the Populated Area of the site was released in October
1990 and the associated Record of Decision (ROD) is expected in mid-1991. A follow-up ROD for
homes, interiors, and commercial properties is expected 1 year after the initial ROD. For the
Nonpopulated Areas, data collection for an Remedial Investigation/Feasibility Study has been
completed. The Remedial Investigation/Feasibility Study for Nonpopulated Areas (including the CIA,
smelter complex, hillsides, ground water, river, and flats) is presently being prepared, and is due for
completion in 1992 (Reference 4).
17-

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Bunker Hill Mining and Metallurgical Complex
REFERENCES
1.	Interim Site Characterization Report for the Bunker Hill Site; Prepared for EPA Region X by
Woodward-Clyde Consultants and Terra Graphics; August 4, 1986.
2.	Bunkei Hill Superfund Site Fact Sheet; EPA Region X; February 26, 1990.
3.	The Coeur d'Alene Mining District in 1963, Pamphlet 133; Idaho Bureau of Mines and Geology;
1963.
4.	Telephone Communication Concerning Bunker Hill Mining and Metallurgical Complex; From
Maria Leet, SAIC, to Sally Martin, EPA Region X; October 22, 1990.
5.	Risk Assessment Data Evaluation Report for the Populated Areas of the Bunker Hill Superfund
Site; Prepared for EPA Region X and the Idaho Department of Health and Welfare by Terra
Graphics; October 18, 1990.
6.	Public Health Advisory, Bunker Hill Superfund Site, Industrial Complex Portion; ATSDR;
October 5, 1989.
7.	Summary of Bunker Hill Remedial Investigation/Feasibility Study, Tasks 0 through 16; Dames &
Moore; December 18, 1990.
18-

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Mining Waste NPL Site Summary Report
BIBLIOGRAPHY
ATSDR. Public Health Advisory, Bunker Hill Superfiind Site, Industrial Complex Portion.
October 5, 1989.
Dames & Moore. Summary of Bunker Hill Remedial Investigation/Feasibility Study, Tasks 0 through
16. December 18, 1990.
EPA Region X and Idaho Department of Health and Welfare. Risk Assessment Data Evaluation
Report for the Populated Areas of the Bunker Hill Superfiind Site. October 18, 1990.
EPA Region X. Bunker Hill Superfiind Site Fact Sheet. February 26, 1990.
Idaho Bureau of Mines and Geology. The Coeur d'Alene Mining District in 1963, Pamphlet 133.
1963.
Leet, Maria, (SAIC). Telephone Communication Concerning Bunker Hill Mining and Metallurgical
Complex to Sally Martin, EPA Region X. October 22, 1990.
Prepared for EPA Region X by Woodward-Clyde Consultants and Terra Graphics. Interim Site
Characterization Report for the Bunker Hill Site. August 4, 1986.
19-

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Bunker Hill Mining & Metallurgical Complex
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From the Interim Site Characterization
Report for the Bunker Hill Site;
Prepared for EPA Region X by Woodward-Clyde Consultants
and Terra Graphics; August 4, 1986

-------
158WP1-T0C SUP-1
TZ4 - cio oih-M- 22213
INTERIM SITE CHARACTERIZATION REPORT
FOR THE
BUNKER HILL SITE
August 4, 1986
WORK ASSIGNMENT NO. 59-0L20
EPA CONTRACT NO. 68-01-6939
Prepared by:
Woodward-Clyde Consultants
and
TerraGraphics
158-WPl-RT-CZLE-

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from 1 to 10 times the global means for their abundance in the earth's
crust. Chemically anomalous areas of high metal concentrations have been
noted in soils near vein outcrops or where industrial contaminants have
been deposited.
Hillside soils near the smelting complex have been severely impacted by
years of sulfur oxide impact and metals deposition. Early fires and
harvest practices destroyed much of the native vegetation and air pollution
prevented new growth. The bare, unprotected hillsides were then severely
eroded, further reducing water holding capacity and rooting depth,
resulting in a coarse gravelly soil with little structure and sparse
vegetation. Soil pH in this area in 1974 ranged from 3.2 to 5.8. Lead
levels in hillside soil range from 1000 to 24,000 ppm; cadmium levels, from
50 to 236 ppm in the top one-half inch. On undisturbed areas most of the
metals are found in the top three inches of soil. In severely eroded
areas, airborne contamination has penetrated to a depth of ten inches or
more.
Soils on the valley floors occur over alluvial and glacial deposits and
range up to 100 feet in thickness. The materials are an unconsolidated
mixture of pebbles, boulders, sand, and clay. The upper 10 to 20 feet of
these materials are interworked to varying degrees with mine and mill
tailings and rock dust generated by the minerals processing industry.
Early milling practices resulted in the deposition of metals-rich tailings
to low-lying areas. These materials were reworked-by flood waters and man
and are now inextricably included in the floodplain surface soils. The
USSCS classifies these soils as Slickens, a term referring to soils
containing mine slimes. Lead and cadmium contamination levels in these
soils are similar to those found on the hillsides.
158-WPl-RT-CZLE-l
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clean-up were materials from discrete waste piles, materials from general
site clean-up, and contaminated equipment, including transformers
containing PCBs. For example, Bunker Limited Partnership (8LP) records
indicate that "approximately 6367.3 tons of cadmium filter material mixed
with mercury contaminated sludge, and 301.7 tons of mercury contaminated
heat exchangers were shipped off site and disposed at Chem-Security1s
Arlington, Oregon site" during the clean-up period (BLP File Folder, 11166
& 11034). Furthermore, waste material movement logs document the removal
and Iransport of over 47,400 tons of waste material to disposal sites on
the smelter complex, mostly to the CIA. Information provided to EPA by the
law firm representing Bunker Limited Partnership (the current owner of the
smel :er complex) identifies seven types of waste remaining which alone
total 36,500 tons (Weatherhead, Folder 3, 1986, 11042): 5000 tons of
copper dross slag tailings (30-35% lead," 10-14% zinc, 2.5-3.5% copper, plus
10	other constituents); 8000 tons of control mix (lead residue)(30-35%
lead, 7-7.4% zinc, plus 12 other constituents); 3000 tons of Sweeney Pond
clean-up materials (30-50% lead, 4.5-14% zinc, plus 11 other constituents);
2500 tons of baghouse product (45-65% lead, 5-11% zinc, plus 18 other
constituents); 12,000 tons of arsenical copper dross flue dust (41-54%
lead, 1-9% zinc, 20-25% arsenic, plus 11 other constituents); and 6000 tons
of zinc plant leach residue (7-13.5% lead, 16-20% zinc, 19-22% iron, plus
11	ether constituents).
Toxicity. The toxicological effects of thirteen contaminants of concern in
the Bunker Hill project area are reviewed in the main report. Eight of the
substances are metals (lead, cadmium, beryllium, cobalt, copper, mercury,
silver, and zinc); two are metalloids (arsenic and antimony); one is non-
metiillic (selenium); one group - the polychlorinated biphenyls (PCBs) - are
a family of chlorine-containing organic compounds; and asbestos is a
generic term for a variety of hydrated silicate materials which can
separate into fibrous particles. Other contaminants may also be of
concern, but have not been identified.
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For each substance a brief description of its geochemistry is given; this
is followed by a summary of its biogeochemistry, a description of its major
effects on human health (especially chronic effects) and freshwater
organisms, and a description of any regulations pertaining to the
contaminant. In addition, summaries of the results and interpretations of
site-specific studies, where they exist, are included.
Lead and cadmium are considered the primary contaminants of concern, mainly
because they have been identified in soil and air samples from the study
area over a long period of time. Lead contamination has also been the
focus of multidisciplinary research in the Bunker Hill area for over ten
years.
The main chronic adverse effects of lead exposure in humans are
interference with hemoglobin synthesis, central and peripheral nervous
system dysfunction, and kidney damage. One of the first signs of lead
toxicity is anemia because red blood cell production requires hemoglobin.
The "no detected effect" level for blood-lead is probably about 10 gg/di
but may be even lower (WHO 1977, 10864). Children, particularly those less
than three years of age, have been found to be the group most sensitive to
lead exposure. This is related to their rapid growth rates, high whole
body retentions, high blood levels, and high brain accumulation rates. At
present, there is no evidence that lead is a teratogen (inducing fetal
abnormalities) and it is not classified as a carcinogen.
Chronic exposure to cadmium has been found to induce renal tubular damage
(irrespective of exposure route) and pulmonary emphysema (through
inhalation). Severe cadmium-induced renal damage can result in
osteomalacia (bone softening) and there is some evidence that chronic
cadmium exposure can lead to hypertension. Additional effects of chronic
exposure are abnormal liver function, moderate anemia, and nonspecific
nervous system disorders. The metal has been reported to be fetotoxic
(toxic to unborn young) and teratogenic. NIOSH (CDC 1985a, 10294) has
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153VPL-EXE SUP-13
these effects have not been documented in human studies. There is no
suggestion in human studies that selenium is a carcinogen.
Thf human health effects associated with chronic exposure to beryllium are
known primarily from studies on occupational inhalation of particulate
beryllium. These effects include lung inflammation and enlargement of the
he.irt, liver, and spleen. There have been no indications that ingestion of
beryllium in any form is harmful to humans except when in very large,
continuing dosages. Beryllium has not yet been associated with human
cancer, but is considered an animal carcinogen (IARC).
A review of the regulatory data pertaining to the contaminants of concern
irdicates that lead, cadmium, and mercury have received the most attention
from federal agencies and independent societies responsible for their
ccintrol in ambient and industrial environments. Of all the contaminants
discussed. National Ambient Air Quality Standards (NAAQS) for the
protection of human health were only available for lead. Ambient water
quality criteria were available for all of the contaminants, and there was
at least one occupational health guideline for all but silver. Ambient
water quality criteria for the protection of freshwater organisms have been
developed for all of the contaminants except antimony, asbestos, beryllium,
and cobalt. PCBs are currently under the strictest regulation, while 2inc
and cobalt, being the least toxic to humans of the substances of concern,
have received the least stringent regulation.
Site/Off-Site Contamination. Lead health surveys and concurrent
epidemiological investigations have found that residual soil contamination
is a primary source of excessive lead intake for young children residing m
this area. Three primary routes of soil pollution have been active in the
last century. Metals have entered the soil by airborne deposition from
smelter operations and reentrained dust, by waterborne deposits resulting
from mine and mill discharges to the local streams, and by mine and mill
wastes deposited directly on or in local soil.
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Polluted soils are a hazard through direct contact For children, and as
windblown dust, and as a component of house dust. Public health surveys
addressing the role of soil and house dust in excessive community lead
exposure were undertaken in 1974, 1975, and 1983. Air pollution surveys
addressing soil as a source of atmospheric metals were conducted in 1974,
1975, 1977, and 1979.
The 1970s studies noted (in comparison to the literature and to other
mining and smelting areas) extremely high concentrations of lead, zinc,
cadmium, and mercury and high concentrations of arsenic and antimony in
local soil. Blood-lead toxicity in local children was found to correlate
most strongly with airborne lead exposure. Soil was identified as a
secondary, but contributing, source of undue lead absorption in children.
Lead and cadmium uptake in locally grown_.foods..was measured at unacceptable
levels. The health significance of other metals, including cadmium in
other media, was not addressed.
In 1983, following closure of the smelter, repeat studies found soil to be
the most significant source of undue lead absorption in local children.
Lead and cadmium uptake in locally grown vegetables continued to be
measured at unacceptable levels. The health significance of cadmium and
zinc levels was not addressed. More than 400 homes were visited in the
1970s, and more than 200 homes were visited in 1983.
Data from these studies were synthesized into a single data base in this
report and preliminary geostatistical analyses were performed to define the
degree and extent of soil contamination in the project area. Most of the
area within the pmjprt area boundaries must be regarded as significantly
contaminated. Extremely high concentrations of lead and cadmium are
indicated around the smelter complex (i.e., 5000-40,000 ppm lead, 80-240
ppm Cd). Very high concentrations (>5000 ppm lead) extend over the city of
Smelterville with a secondary high concentration area centered over the
Smelterville Flats.
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Within the cities themselves, the mid-section of Smelterville shows lead
levels exceeding 5000 ppm with the remainder of town having levels between
2500 and 5000 ppm Pb. Most of Kellogg falls in this latter range, with a
Few locations having values in excess of 10,000 ppm. Pinehurst, generally,
hes soil lead concentrations less than 1000 ppm.
01 her metals were examined and show similar patterns of distribution.
Lead, cadmium, and mercury levels are the most elevated above natural
concentrations. These metals are 8 to 300 times local background levels in
Kijllogg and Smelterville with significant portions of residual soils
exceeding 50 ppm cadmium and 10 ppm mercury. Other metals notably elevated
above background concentrations include arsenic (2 to 5 times), antimony (2
to 18 times) and zinc (2 to 11 times).
Redistribution of these soil contaminants is of concern. Many of the more
polluted areas are barren and are significant sources of windblown dust.
There is suggestive evidence that certain metals (notably cadmium) may be
redistributing within the soil profile and becoming more available to
children.
Surface Water Contamination. The South Fork of the Coeur d'Alene River
(SFCOR) has been receiving mine and mill wastes for almost ninety years.
The Bunker Hill complex has made a significant contribution to the
pollution of the SFCDR, some of its tributaries, the main stem of the Coeur
d'Alene below Enaville, and of Lake Coeur d'Alene. In two years, 1973 and
.974, the Bunker H111 complex was estimated by I0HW (1975, 30071) to have
contributed 98.7 and 95 percent of the total SFCDR basin loading of heavy
tnetals, respectively.
Sources of pollutants to the SFCOR and its receiving water have included
direct discharge of acid mine drainage to the river by Bunker Hill
operators (until 1965), direct discharge of lead smelter and zinc plant
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L53wPi-t*E 5uP-2i
wastes (until 1974), direct discharge of central impoundment pond and
gypsum pond water to SFCDR (until 1974), seepage from the Central
Impoundment Area (continues presently), numerous accidental spills
(equipment failure, etc.) of contaminants into tributaries of the SFCDR,
contaminated overland flow from interaction with airborne deposition of
heavy metals, and reworking by the SFCDR of unconfined mine tailings (the
Sme1tervi11e Flats area, primarily) which had been deposited previously by
mine and mill operators in the drainage.
Pollutants which have been measured at significant concentrations (above
EPA Drinking Water Standards) over the past 20 years in the SFCDR (at or
downstream of the project area) include the following (maximum yearly mean
reported and year reported): arsenic (144 ug/t in L971 versus the EPA
drinking water standard (DWS) of 50 ug/t); cadmium (500 ug/t in 1979
versus DWS-10 ug/t); chromium (581 ug/i in 1971 versus DWS-50 ug/t);
fluoride (16.0 ug/t in 1971 versus DWS-1.4-2.4 ug/i); iron (16,000 ug/t in
1978 versus DWS-300 ug/t), lead (1200 ug/t in 1971 versus DWS-50 ug/t);
manganese (5758 ug/t in 1976 versus DWS-50 ug/t); mercury (250.0 ug/t in
1976 versus DWS-2.0 ug/t); selenium (10.0 ug/t in 1972, no DWS); and zinc
(79,000 ug/t in 1972 versus DWS-5000 ug/t) (EPA STORET water quality
summary data 1985). Seepages have concentrations of pollutants which in
many cases are much higher than those reported above. Levels of pollutants
have been so high that there is no year-long resident population of fish
inhabiting the SFCDR in or below the project area to the confluence of the
SFCDR and the mainstem of the Coeur d'Alene River. However, it has
recently been noted that in the last few years, kokanee runs are believed
to have passed through the SFCDR to up near Mull an, Idaho (Horner 1985,
11017).
The concentration of heavy metal pollutants measured over the last 20 years
has been reduced significantly. Three periods of significant reduction in
heavy metal pollution of the SFCDR have occurred. The first happened in
1968, when tailings ponds were mandated and trapped most of the suspended
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58WP1-EXE SUP - 22
materials from the mine and mill wastes. The second occurred in 1974, when
treatment of outflow from tailings ponds was required and zinc plant and
lead smelter effluents were routed to the CIA. The last period of water
sollution reduction occurred in 1981 when the Bunker Hill complex was
:losed down by Gulf Resources and Chemical Corporation.
However, many pollutant concentrations in the SFCOR in or below the project
area remain above those found in the main stem of the Coeur d'Alene River
(CDR) above the confluence of the COR and SFCDR. The most recent water
quality data on the SFCDR were taken in September 1984 (low flow
conditions). The contaminants whose concentrations were still significant
include cadmium (28.6 ug/i versus DWS-10 ug/t), iron (1146 ug/t versus
DWS-300 ug/t), manganese (1507 ug/i versus DWS-50 ug/i), and zinc
(3270 ug/i versus GWS-5000 ug/i). Again, concentrations of many of the
pollutants were much higher in seepages from the CIA. Silver King Creek
and Bunker Creek had concentrations of contaminants which in many cases
were higher than the SFCDR. These contaminants include cadmium, lead,
manganese, zinc, and sulfates.
The current water quality of standing waters on the 8unker Hill complex is
not well known. The CIA still contains very high levels of contaminants
and many of the other ponds on the complex may contain hazardous levels of
contaminants. An inspection of the site revealed the poor condition of
waste stream runout collection systems and the numerous areas where runoff
originates from or passes through some potentially highly contaminated
areas. Many ponds were observed to be in poor condition (i.e., liners
broken) as well. Additional studies will be required to fully understand
the origin and transport of contaminants both within the complex and the
project area-.
Groundwater Contamination. The project area contains several possible
major sources of groundwater contaminants, including: the CIA, the
unconfined mine and mill wastes at Smelterville Flats, and the Page
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153WP1-EXE SUP-23
wastewater ponds. With its high concentrations of zinc, lead, cadmium, and
other metals, the CIA is the likeliest source of contamination. Zinc and
cadmium levels as high as 50 mq/i Zn and 0.1 mg/i Cd occured in wells
adjacent to the CIA.
Many studies have covered the occurrence of seepage from the CIA, but few
have defined the spread of contaminants beyond a perimeter well network
established by Bunker Hill Co., EPA, and others. Evidence seems to
indicate that CIA leakage enters the groundwater in the unconfined aquifer
and probably enters the South Fork. Based on Robinson et al. (1980,
10181), the CIA discharged "2
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Air Quality. Air quality monitoring of particulates and lead by IDHW has
shown a dropoff in both contaminants following the late 1981 cessation of
lead smelter operations, and, as well, a reduction in sulfur dioxide, also
due primarily to the cessation of smelter operations.
Monitoring of particulates indicated that the greatest lead content is in
the smallest, respirable particulate fraction, which is the most subject to
lung retention and absorption. No current inventory exists of within-
complex or on-site fugitive dust sources, the probable most important type
of air contaminant source since the lead smelter shutdown.
Emissions from the lead smelter main stack were calcuated for the period
1965 through 1981 for lead, cadmium, zinc, mercury, and arsenic;
significant amounts of each were emitted throughout that period, both
before and after Installation of the taller lead smelter main stack in
1977. In excess of 6,000,000 pounds of lead; 560,000 pounds of cadmium;
860,000 pounds of zinc; 29,000 pounds of mercury; and 70,000 pounds of
arsenic were emitted in 1965-1981, indicating air emissions were a
continuing significant source of concern. There are a number of
uncertainties in these calculations, but these values provide an order of
magnitude indication of the levels involved. These uncertainties include
quality assurance and quality control of the data and whether all emission
sources to the stacks were measured. These figures are for the lead
smelter main stack, and do not include vent and fugitive emissions believed
to total more than stack emissions.
Contaminant Pathways Conceptual Model
Contaminant movement through the environment from contaminant sources to
humans is discussed through use of a compartment and net transport pathway
models. Compartments are environmental segments where contaminants may
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158WP1-EXE SUP-25
reside, accumulate, and undergo physical and chemical transformations.
Pathways are direct or secondary routes from sources to human receptors via
compartments; the sum of the transfer rates on each of the pathways leaving
a particular compartment is the dispersion rate of the contaminant. For
example, one contaminant compartment/pathway route would involve material
moving from a source area (for example, a storage pile in the smelter
complex), via air transport (wind erosion of the pile and airborne dust),
to deposit on the soil surface (for example, in the yard of a residence).
Finally, from there the contaminant is subject to direct ingestion by
infant or toddler hand-to-mouth behavior.
Site-Specific Pathways. The first part of Section 4 discusses the current
conceptual air and water pathways of the project area. Schematic diagrams
are presented for each pathway type (air or water), which depict
contaminant sources (e.g., the Page Tailings Pond, Smelterville Flats, the
smelter complex, the CIA, and hillsides in the area) and the major human
population centers (Pinehurst, Smelterville, and Kellogg). Arrows are used
to represent pathways, and an arrow typically leads from a contaminant
source to populated geographic areas where humans in the project area may
receive exposure. The major exceptions are when an arrow originates off
site and enters the project boundary (import) or when it originates from
the project boundary and terminates off site (export). A series of arrow
symbols represent a series of tentatively projected scales of pathways
(i.e., large, intermediate, small, and potential or suspected). These
pathways should be considered as hypotheses subject to changes as new
information is gathered.
The conceptual air pathways schematic diagram indicates that the net
movement of contaminants in the project area is from west to east. This is
a result of the dominance of winds from the west in the region. As a
consequence, Pinehurst receives the least amount of contamination from
project area contaminant sources via the air pathways, and the hillsides
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Air Quality. Air quality monitoring of particulates and lead by IDHW has
shown a dropoff in both contaminants following the late 1981 cessation of
lead smelter operations, and, as well, a reduction in sulfur dioxide, also
due primarily to the cessation of smelter operations.
Monitoring of particulates indicated that the greatest lead content is in
the smallest, respirable particulate fraction, which is the most subject to
lung retention and absorption. Mo current inventory exists of within-
complex or on-site fugitive dust sources, the probable most important type
of air contaminant source since the lead smelter shutdown.
Emissions from the lead smelter main stack were calcuated for the period
1965 through 1981 for lead, cadmium, zinc, mercury, and arsenic;
significant amounts of each were emitted throughout that period, both
before and after installation of the taller lead smelter main stack in
1977. In excess of 6,000,000 pounds of lead; 560,000 pounds of cadmium;
860,000 pounds of zinc; 29,000 pounds of mercury; and 70,000 pounds of
arsenic were emitted in 1965-1981, indicating air emissions were a
continuing significant source of concern. There are a number of
uncertainties in these calculations, but these values provide an order of
magnitude indication of the levels involved. These uncertainties include
quality assurance and quality control of the data and whether all emission
sources to the stacks were measured. These figures are for the lead
smelter main stack, and do not include vent and fugitive emissions believed
to total more than stack emissions.
Contaminant Pathways Conceptual Model
Contaminant movement through the environment from contaminant sources to
humans is discussed through use of a compartment and net transport pathway
models. Compartments are environmental segments where contaminants may
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Kellogg is upstream from most of the major contaminant sources in the
project area. The water pathways originate from airborne contaminants in
precipitation, hillside runoff, stream flow, and groundwater recharge, and
contaminant transferrals directly from the SFCDR and GW as water flows
through Kellogg. Both the SFCDR and GW contain contamination derived from
upstream sources. However, as they leave the project area at the western
boundary (Pinehurst), the water pathways exhibit large increases in many
contaminant levels over those observed entering the project area at the
eastern boundary (Kellogg). These include observed increases in the SFCDR
(September 1984) of 310 percent for sulfate, 1475 percent for phosphorus,
1350 percent for fluoride, 40 percent for cadmium, 190 percent for copper,
5200 percent for iron, and 40 percent for zinc (Section 3.3.3.2).
From Kellogg, the SFCDR and GW flow past the CIA and the smelter complex.
The level of contamination in the SFCDR and GW rises during transit. As
those water compartments pass Smelterville, contaminant transferral to and
from Smelterville is expected. Smelterville also receives waterborne
contaminants from precipitation and from the hillsides.
The SFCDR and GW next pass Smelterville Flats and the Page Tailings Pond.
Intermediate levels of contaminant transferral-to the SFCDR are projected
to occur during transit, with the groundwater receiving contaminants as
wel 1.
Pinehurst is located at some distance from the SFCDR and GW compartments as
they exit the project area. While there is a potential for the water
compartments to transfer contaminants to Pinehurst, the existence of such
transferrals is questionable and has not been documented. Pinehurst does
receive contaminants in precipitation and from runoff, stream flow, and
groundwater recharge from the hillsides.
General Human Receptor Model and Site-Specific Health Studies. The second
part of Section 4 discusses a conceptual model which summarizes the general
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158WP]-EXE SUP-28
(not ;ite-specific, except for lead) exposure pathways for contaminants to
directly reach human beings. Aspects of this model differ from the
previously described schematic models and the terminology is explained;
more specifics about generalized sub-pathways are presented. Reviews for
lead, mercury and zinc are presented. In addition, historically recorded
contaminant levels are reviewed. The third part of Section 4 discusses the
results of site-specific health studies. Extracts from contaminant and
heaUh studies are provided below.
In l')74, the residential mean lead levels were 11,920 ppm for household
dust, 7224 ppm for soils, and 231 ppm for garden lettuce (for residences
within 1 mile of the smelter). In 1983, dust lead levels averaged 3994
ppm, soil lead levels averaged 3504 ppm, and lettuce contained 48 ppm.
Residential mean cadmium levels (for residences within 1 mile of the
smelter) in 1974 were 63 ppm for soils and 28 ppm for garden lettuce (dusts
were not analyzed for cadmium in 1974). The 1983 values were 54 ppm for
soils, 5 ppm for garden lettuce, and 67 ppm for household dusts.
The 1974 residential mean zinc levels (for residences within 1 mile of the
smelter) were 2340 ppm for soils (garden lettuce and dusts were not
analyzed for zinc). Levels in 1983 were 126 ppm for soils, 2840 ppm for
household dusts, and 73 ppm for lettuce.
Lecd, zinc, cadmium, arsenic, PCBs, silver, selenium, copper, beryllium,
mercury, antimony, asbestos, and cobalt are discussed further in the
to;:icological effects section of the report- These are the constituents
found repeatedly at high levels in the Silver Valley, or recorded within
the Bunker Hill complex and potentially liable to release if proper care is
not exercised during cleanups or remedial Action. The population
potentially at risk of exposure is relatively well known, based on the
earlier surveys of blood, soil, household, and vegetative lead content.
Documented lead concentrations and body lead indicators can serve as
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iSOrtr" 1-tAL Jur-^3
indicators of the routes of population exposure to contaminants of concern
in general because of the ubiquitous nature of lead's origin points within
the complex and throughout the site, and its measured concentrations with
respect to particle size for air pathway exposure.
In 1974, over 98 percent of 172 children living within one mile of the
smelter had blood-lead levels exceeding 40 ug/da. The following
information is from the report, "Kellogg Revisited in 1983: Childhood
Blood Lead and Environmental Status Report" (CDC/IDHW 1985, 10613).
Blood-lead levels in children from Smelterville residences (survey area 1)
in the 198.'. Survey ranged from 6 to 35 ug/da, with a mean of 21 yg/da.
Mean blood-lead levels in that area dropped from 68 ug/da. in 1974, to 31 in
1980, to the 1983 level. Area 2 (Kellogg, Wardner, Page) has dropped from
49 in 1974 to 26 in 1980 to 17 in 1983. Correlations between blood-lead
levels and children's home settings, socioeconomic factors, parental
occupation, and other factors were calculated. Strong correlations were
found with residential-area sail lead levels, household dust lead levels,
and (to a lesser extent) childhood mouthing behavior and other factors.
The number of children surveyed in 1983 was 364. In 1985, a follow-up
survey to the 1983 investigation was initiated. The survey, performed by
the Panhandle Health District under a Centers for Disease Control (CDC)
grant, screened a total of 348 children between the ages of 9 months and 9
years living in the cities of Kellogg, Smelterville, and Wardner. Of those
children, 10 were identified as having blood-lead levels exceeding the
CDC's limit of 25 ug/da. That number represents a significant reduction
from the previous studies. However, the highest blood-lead level measured
in the area since 1979, 59 ug/da in a 4-year-old child, was recorded in the
survey. In addition, a blood-lead level of 51 ug/da in a 15-month-old
child was also recorded in the 1985 survey.
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158WPJ-EXE SUP-30
Data Kequirements
Oata -equired for proper initiation of the site remedial investigation (RI)
primarily center on detailed surveys of the extent of Bunker Hill complex
contamination liable to transport to surrounding areas, and assessing the
investigation of "hotspots" outside the smelter complex above "natural"
(area-average background) baseline concentrations.
Major segments of additional data needed include:
•	sampling of current ponds,	piles, deposits, dikes, and structures
on and off the Bunker Hill	complex - limited comfirmatory sampling
for those areas where 1982	sampling data are available, with
broader sampling of wastes	not yet characterized
•	groundwater well monitoring
•	establishment of surface water and groundwater baselines for water
quality comparisons
•	a detailed meteorology and air quality survey of the complex and
the surrounding site areas, to bring knowledge of winds and
contaminant emissions up to date for the current plant situation;
this should include:
-	installation of a quality-controlled meteorological station, to
provide good data on winds in the area
-	ground survey and analysis of fugitive particulate sources
reported in earlier emissions inventories, for confirmation of
source size, probable ease of wind resuspension of material from
the source, and current composition with regard to contaminant
composition
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-	survey and analysis of off-complex materials within the site
area that are likely to represent sources of fugitive
particulates
-	remodeling of current complex/off-complex source configurations,
using newer, higher-quality meteorological data and detailed
source emissions data
•	additional analyses of existing soils data and supplemental
sampling for residential soils:
-	verification of the usefulness of historical data in current
analyses
-	substantial additional sampling and further characterization of
the potential hazard soils contamination presents to the local
population
-	analysis of contaminant distribution with depth in soil profile
-	additional analyses of newly collected and archived soil samples
for other metal contaminants
*	field survey and analysis of previous revegetation efforts:
-	survival and continued growth of original plantings
-	degree of invasion by other species not originally included m
the plantings
-	extent of current vegetative ground cover and litter cover
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158WP1 -EXE SUP-32
-	relative success of revegetation in controlling wind and water
erosion
-	current soil contamination in the area, and possible role of
revegetation in ameliorating soil conditions
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1.0 INTRODUCTION
1.1 SITE LOCATION
The Bunker Hill Superfund project area is approximately 7 miles long and 3
miles wide, bounded on the west by the town of Pinehurst and on the east by
the town of Kellogg In Shoshone County, northern Idaho. The Bunker Hill
complex lies off Interstate Highway 90, about 380 miles north of Boise and
about 60 miles east o* Spokane, Washington, in the Silver Valley of the
South Fork of the Coeur d'Alene River. The valley winds from east to west
through mountains ranging from approximately 500 to 2500 feet above the
valley floor, which lies approximately 2200 to 2300 feet above sea level
(Figure 1-1). Project boundaries shown in Figure 1-1 are representations
of section boundaries shown on the USGS 7.5 minute Topographic Maps
"Kellogg East, Idaho" and "Kellogg West, Idaho." The section boundaries on
the USGS maps are authoritative.
Within the site boundaries is the Bunker Hill mining complex, located
between the towns of Kellogg & Smeltervllle. The complex consists of a
mostly inactive integrated mining, milling, and smelting operation, which
includes the Bunker Mine (lead and zinc), a milling and concentrating
operation, a lead smelter, sjlver refinery, electrolytic zinc plant,
phosphoric acid and phosphate fertilizer plant, sulfuric acid plants, and a
cadmium plartt (Figure 1-2).
All of the Bunker H111 facilities are located on the south side of the
Silver Valley, and cover a total of approximately 350 acres. The lead
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I	S*«UU* Pondli	14 IWa|«9N«vm
I	Zinc	II NvKmmf
3	Stack	|| Imw haducikM
«	Wait fondi	If FeUeiUl»eS«U<>*e
t	AiMnQAkn»Nt««MMf^i II e«ddh*f BwU*^
•	|ih*i ttlnf School	19 •tan** felt**
t	tin—ny fond	90 CaMa| Plant
I	|lKlil(AfcNiA«c«M| 21 WaiMwir liitimtnifliAi
•	StlMl R«HMry	}t CMtMUItiM luMui|
10 iMd Rltlwqi	IS CnuMf
U	|l«l Immk* Aim	>4 Mm«r> &v**Ag Smldlnf
I]	|lw	fl»n|	26 Utn« En|r*nc«
I)	fmHMH	30 Ctacului f0«w tub Su
l
• N "
I
Figure 12. BUNKER HILL MINING COMPLEX
isa WP1 -fl T-czlc i

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1 )0«r i-J i J«r -<¦
sine 1ter takes up 98 acres on a foothill just above the valley floor. The
zinc plant takes up 86 acres in a side canyon 1 mile to the south. The
fertilizer plant lies on 13 acres north of the zinc plant, and the
cancentrator and Bunker Mine lie 0.5 and 1 mile east of the smelters,
respectively. The Central Impoundment Area (CIA), which served as the
major disposal site for mine tailings and wastewater solids from the
facilities, is located northeast of the lead smelter and accounts for 46
percent of the total area of the complex, covering 160 acres. The
locations of these areas are shown in Figure 1-3.
1.2 SITE STATUS ANO PROJECT OBJECTIVES
Cnly the Bunker Hill mine pumps, the wastewater treatment plant, and the
jinc concentrate dryer (under lease to another mining company) are
currently active. The rest of the complex was closed in approximately
December of 1981. The Crescent Mine (outside the project area) and the
Crescent Circuit of the Bunker Hill Mill (within the project area) were
reopened in late 1983, but closed on May 30, 1986.
During the past operation of the Bunker Hill facilities, a variety of
hazardous substances—the products and by-products of the mining, milling,
and smelting activities—were released into the surrounding environment.
Hvidence of possible contamination from these substances was found in the
elevated blood-lead levels of local children during the early 1970s, and
igain in 1983. In response to a mandate from the Environmental Protection
Agency (EPA), acting under the authority of the Comprehensive Environmental
Response, Compensation & Liability Act of 1980 (CERCLA, or Superfund), the
site was given priority listmg for Superfund remedial action, and an
investigation of the extent and nature of site contamination was
initiated. The Bunker Hill Site Characterization Report (SCR) is one of
the first steps in that remedial investigation.
1-3
158-WPl-RT-CZ.

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KELLOGG
Figure 13. BUNKER HILL MAP
158-WPl-HT-CZLfc I

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15bnPl-Si ^-3
The objective of the SCR is to describe and analyze existing information.
The information examined includes site characteristics, contamination, and
contaminant effects on human health and the environment. The purpose of
this description and analysis is threefold: 1) to define the problem, 2)
to avoid re-gathering data which already exist during the remedial
investigation, and 3) to provide a base under the Superfund process to
support our decisions. The SCR can then be used to identify data gaps and
to develop a Work Plan to govern the investigation and remedial
activities. Selecting the appropriate remedial action requires careful
planning to provide an effective long-term solution to the contamination
p-oblem. A Work Plan will be developed based on the SCR information which
will outline the projected scope of the Bunker Hill Remedial Investigation
(SI) and Feasibility Study (FS)- The Remedial Investigation will
supplement the existing data in the SCR with new data gathered to fill in
data gaps about site conditions and especially to aid in the evaluation and
selection of remedies. The RI/FS will be combined 1n a document which
describes possible alternatives for remedial action in the project area.
Once all feasible alternatives have been considered, one or more cost-
effective remedial measures will lie selected.
lhe data used in the SCR were gathered from the files of appropriate
federal, state, and local agencies. Information from the files of the
flunker Limited Partnership (the current owner of the property and of the
prior owner's data) had not yet been made available to EPA for inclusion in
i;he draft of this report, but has subsequently been obtained, reviewed and
included in the final report. An inspection of the Bunker Hill complex has
been conducted to supplement the data contained in the draft SCR and is
referenced later 1n this repdft, particularly in Section 3.1 (Wastes
Disposed of at the Site).
158-WP1-RT-CZLE-1
1-5

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1.3 OVERVIEW
The contaminants of concern in this report are lead, zinc, cadmium,
antimony, arsenic, beryllium, copper, mercury, PCBs, selenium, silver,
cobalt, and asbestos. The last two were added as a result of the smelter
inspection of November 1985, which found them present. Other contaminants
may also be of concern in the project area. The metals given the most
attention because of their pervasiveness or acute toxicity are lead,
cadmium, and zinc.
The environmental contaminant transport pathways discussed here include air
emissions, surface and groundwater, soils, and fugitive dust. Air intake
and direct contact with contaminants are considered the most critical
transport modes to examine. However, the separate and interrelated effects
of all potential transport pathways will be considered at a later time in
order to fully characterize the nature and extent of contamination in the
project area.
Specifically, Section 2, Site Description, describes Bunker Hill's baseline
environmental setting as it potentially affects transport and movement of
contaminants. This section also discusses those contaminants which are not
of immediate concern to the project as part of the background discussion;
those which are of immediate concern are discussed in Section 3. For
example. Subsection 2.1.5, Meteorology and Air Quality, contains a site
history of air emissions, such as sulfur dioxide, which are not of current
concern. Other air quality contaminants, such as lead, are the focus of
Section 3.
Section 3, Definition of the Contamination Problem, discusses all
documented substances disposed of on the Bunker Hill site that require
remedial investigation under Superfund. This discussion includes
identification of the on-site sources of these substances, and how they
were generated by past site operations. The location and the
158-WPl-RT-CZLE-i
1-6

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i:o«ri-ji jur - a
chemical/physical form of disposal of each substance are also described. A
general discussion of the toxicity of contaminants of concern follows,
including a description of their behavior in the biological and physical
environment. A summary of the guidelines, criteria, and standards which
regulate these toxics is also given in Section 3.
Section 4 provides guidelines for further investigation of remedies to the
environmental movement of contaminants by presenting a conceptual model of
migration pathways from source areas to humans.
Suction 5 is a summary of remaining data requirements, the information not
included in the report due to access difficulties or considerations of
rulevancy. Where inadequate information was available to give a complete
characterization of some aspect of the site, this is clearly noted.
1-7
158-WP1-RT-CZLE-I

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content in these soils to range from 1150-23,600 ppm Pb and 5.8-236 ppm
Cd in the close-in barren areas; and from 88-615 ppm Pb to 6.6-7.4 ppm
Cd at the west end of the project area (IOHW 1974a, 10751). Metals
concentrations at these sites were also examined in profile. On
undisturbed plots, more than 40 percent of the total lead in a 6-inch
t
profile was confined to the top inch of the soil profile with nearly 80
percent being found in the top 3 inches. Others have found similar
concentrations and gradients with depth (Gott and Cathrall 1980, 33215;
Keely 1979, 50226; Keely 1976, 10454). Soil pH values measured in the mid
1970s were low on all hillsides in the study area, ranging from 3.2 to 5.8.
The residual soil structure and low pH values found at the inner areas near
the smelter have resulted in complex phytotoxicity factors. Not only are
the accumulating trace metals potentially toxic to plants, but soil fauna
and microflora are exposed to an acidic environment that can render common
earth elements toxic as well. The situation, however, is dynamic and some
greening of the hillsides is evident since the installation of tall stacks
in 1977 and smelter closure. Few data are available to ascertain or assess
chemical changes in hillside soils in the last few years. The U.S. SCS is
currently remapping the area and this information should be of considerable
use to the project.
Valley Floor. Soils on the valley floors, and particularly in the
floodplains, vary significantly in their physical characteristics and
genesis from those on the hillside. The soils underlying the study area
are alluvial and glacial deposits resulting from the erosion of the
regional belt series rock and reworked glacial terrane deposits (Norbeck
1974, 30057; Williams and Ralston 1976, 50016). There is some evidence of
regional loess contribution and volcanic ash, most notably the recent Mount
St. Helens deposit. However, the soils are largely alluvial and derive
their dominant physical characteristics from hydrologic and anthropogenic
factors.
158-WP1 -RT-C: -:
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158WI»1-S2 SUP-9
The /alley of the SFCOR is underlain by these soils varying in depth from
30 faet at Wallace to over 400 feet at Rose Lake. The materials are
described as an unconsolidated mixture of rounded pebbles, boulders, sand,
and clay. In the project area, depths of these sediments are stratified
with an upper layer of 15 to 20 feet of river gravel underlain by 10 to 15
feet of surficial silts covering a lower gravel layer (Norbeck 1974, 30057;
Williams and Ralston 1976, 50016; Mabes 1977, 50011).
The upper 10 to 20 feet of these soils on the valley floor are interworked,
to varying degrees, with mine and mill tailings and rock dust generated by
the minerals processing industry in the early part of this century. The
degree of contamination associated with these unconfined tailings deposits
depunds on a number of factors. Most notable among the determinants are
reUtion to the river, proximity to past disposal sites, and the degree of
reworking accomplished either by nature or man.
Beginning in the late 1800s, tailings and slimes from many of the mine and
mill operations were often discharged directly into the river where they
would be carried downstream (Mabes 1977, 50011). Other disposal practices
included fluming of waste mill products to convenient locations where the
material would accumulate according to the local terrain. The earliest
mill discharges were known as jig tailings and are described elsewhere in
this document. These materials were particularly high in metals and became
a dominant chemical determinant in soils where they were directly disposed
and in floodplain areas where they were reworked by river waters into the
upper soils levels. In later years these jig tailings deposits were
reworked by man in metals recovery operations. This resulted in a
significant decrease in total metals load in the low-lying soils of the
valley. However, the reworking disseminated the residual tailings
throughout the surficial river gravels and the resultant depth of
contamination likely exceeds 10 feet today (Williams and Ralston 1976,
50016; Ioannou 1979, 50002). The U.S. SCS refers to these soils as
Slickens (U.S. SCS 1974, 35203).
2-12
158-WPl-RT-C:

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River Channel/SmelterviHe Flats. There are several dominant features
in the project area today associated with the past tailings deposits.
They are the Smelterville Flats area, the Page ponds, and the Central
Impoundment Area (CIA). The Smelterville Flats encompass an area of
approximately 2 square miles north and west of the City of Smelterville
where significant amounts of unconfined tailings have accumulated over this
century (IDHW 1979, 10513; Iannou 1979, 50002). In the very early years
(circa 1910) complaints from downstream agricultural interests convinced
the mining industry to build a dam at the head of the Smelterville Flats to
contain a major portion of the district's waste discharge to the river.
This resulted in the flats area becoming a settling pond for the district
for over twenty years. The dam was washed out by a flood in the early
1930s and, in the following 20 years, this area was reworked for commercial
grade tailings recovery. The remains of the accumulated tailings deposits
can, reportedly, be seen in the river cut today (Ioannou 1979, 50002).
Similarly, the river channel itself contains residual tailings materials
and cuts through these deposits, resulting in a continual erosion and
redistribution process. Numerous samples have been collected in the
floodplain flats area. Although the entire area can be classified as
highly contaminated, several researchers have noted considerable
variability in the chemical composition of the area. Most of that
diversity is important to water quality considerations and is discussed in
another section. With respect to fugitive dust and health concerns,
surface metals concentrations range from 6000 ppm to 25,000 ppm lead, and
30 ppm to 70 ppm cadmium (PES 1979, 10770). The area is largely devoid of
vegetation.
Page Ponds/CIA. The combined influences of a limited availability of flat
land and the continued accumulation of tailings and advances in minerals
processing technology helped create disposal techniques that began
containing mill tailings. There are two massive examples of confined
tailings in the study area. They are the Page ponds and the CIA. These
features have far reaching effects in several environmental media and are
15S-WP1-RT-CZLE-
2-13

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iaawn-i^ ^ur-u
best discussed in other sections of this report. They do, however, cover
some 240 acres of the study area, contain several million cubic yards of
tailings, and are located near the major residential areas. Metals content
in these piles ranges from 2000 ppm to 20,000 ppm lead (Ralston et al.
1973, 30017; Mabes 1977, 50011; I0HW 1974, 10750). The primary concerns
with these features with respect to health and soil are their ultimate
disposition and what measures can be taken to minimize recontamination by
blowing dust.
2.1.2 TOPOGRAPHY
The project area occupies a 7-mile by 3-mile section of the east to west
trending valley of the South fork Coeur d'Alene River and adjacent
mountainous uplands. The valley, known as the Silver Valley, is an
alluvial floodplain bounded to the north and south by steep mountains
(Figure L-l).
The floodplain ranges in width, in the project area, from 0.11 mile above
Kellogg, Idaho to 0.85 mile in the vicinity of Smelterville Flats and the
Paje Tailings Ponds (Figure 1-1). Elevations in the valley range from
approximately 2160 feet at the confluence of Bear Creek and the South Fork
Coeur d'Alene River at the west end of the project area to 2320 feet at
Ross Gulch at the east end. The valley floor is level to nearly level (0
to 1 percent slopes).
Elevations of the mountains adjacent to the river valley range from
approximately 2700 feet above sea level along Kingston Ridge and Blue Star
Ridge near Pinehurst, Idaho to over 4500 feet above sea level along a
ridge/spine ab'ove Wardner, Idaho between Oeadwood Gulch and Milo Creek.
These elevations are 500' to 2500' above the valley floor, which ranges
from 2200-2300 feet above sea level. Mountain sides typically exhibit
slopes of 45 to 90 percent and may exceed 110 percent in some locations.
Numerous parallel valleys of gulches and creeks cut through the mountains
158-WPl-RT-C:'-:"
2-14

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158WP1-S2 SUP-14
2.1.3.2 Surface Drainage
The drainage network of the Coeur d'Alene River Basin is shown in Figure
2-4. The South Fork of the Coeur d'Alene River (SFCOR) and its tributaries
are shown in Figure 2-5. The major creeks on the Bunker Hill complex are
shown on Figure 1-3 in Section 1.
The SFCOR below Wallace is a relatively shallow and swiftly flowing stream,
with a gradient of about 30 feet per mile. Since mining activities in the
area began, the streams in the vicinity have received a heavy sediment load
composed of mine and mill tailings. The SFCOR has received a sediment load
much larger than its transport ability, causing significant filling of the
main channel and alteration of its original course, [n the wider flood
plain areas, the river has become a meandering stream with braided
channels.
Several USGS flow gauging stations are present in the area at locations
listed in Table 2-3. The average total yearly flow of the SFCDR at
Smelterville during the period from 1967-74, as shown in Table 2-3, was
331,100 acre-feet (average of 457 cfs for one year), while at Kellogg from
1974 to 1983 (after the gauge was moved upstream from Smelterville in 1974)
the average total yearly flow was 268,900 acre-feet (average of 371 cfs for
one year). These flow levels are approximately 14 to 18 percent of the
average total yearly flow of the Coeur d'Alene River (CDR) at Cataldo
(downstream from the confluence of the CDR and SFCDR). The annual mean
flows observed at Silverton, Smelterville, and Kellogg are shown in Figure
2-6. As indicated above, in 1974 the gauge at Smelterville was moved about
1.9 miles upstream to Kellogg. The drainage area for the upstream station
is 4 percent smaller. The difference between the tM annual totals at
Smelterville and Kellogg must be mostly attributable to a drier period
occurring between 1974 and 1983. If one compares the deviation between the
annual mean flows to the overall yearly mean flow at each of the gauge
158-WP1-RT-CZLE-1
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Smellerville
Caialdo
Kellogg
JPinehursl
O gU
Sllverton
Oiburn
Mullan
Wallace j
Figure 2-5 SCHEMATIC MAP OF THE SOUTH FORK COEUR D'ALENE RIVER
AND ITS TRIBUTARIES
158 WP1 RT-C^Lfc 1

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I5BWPI-I2 SOP-2
TABLE 2-3
SUMMARY OF S1REAMFLOWS - SHOSHONE COUNTY
USGS
Gage
Number
Stream And Location
Drainage
Area
(Sq HI)
Average
Record .
(Wtr Yrs )
Total
Average
Runoff
(Ac. Ft)
Extremes
Max
(cfs)
of Discharge
Date
Hln
(cfs)
Date
12411000
12413000
Coeur d'Alene River
above Shoshone,Creek
at Enavflle
335
895
1951-76
1940-76
545,000
1,437,000
22,000
61,000
1/15/74
1/16/74
34
104
12/26/52
12/26/52
1241 3)40
Placer Creek at Wallace
14.9
1968-76
32,100
1,200
1/15/74
2.2
12/5/72
1 ? 41 31 50
12413300
12413250
South Fork Coeur d'Alene River
at SI lverton
at Smeltery tile
at Kellogg
103
202
194
1968-84
1967-74
1974-83
183,200
331,100
268,863
4,300
11,500
7,250
1/16/74
1/16/74
2/21/82
31
50
35
1/13/75
12/8/73
IZ/30/79
12413400
Nest fork P1ne Creek near Plnehurst 10.B
1967-71
25,700
505
5/13/71
2.2
9/14/69
12413600
Coeur d'Alene River near Cataldo
1,200
1921-72
1,850,000
67,000
12/22/33
122
12/4/29
l?4l 3100
Big Creek near Kellogg
20.9
1972-74
47,347
1,500
1/16/74
4.0
12/5/73
Source; EIsenbarth and Urlgley 1978, 30076 (from 11SGS Records)
'October through September
158-HPl-RT-CZLE-

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O 1
o -
Smelterville
o -
Kellogg
u
5
o
c
m
at
s
Silvenon
o
1970
1966
1974
1978
1982
1986
Year
Figure 2-6. ANNUAL MEAN FLOWS SOUTH FORK COEUR D'ALENE RIVER
AT SILVERTON, KELLOGG AND SMELTERVILLE
DURING WATER YEARS 1968-1984
2-24
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_ c

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15BWPI-T2 SUP-3
TABLE 2-7
SUMMARY OF OBSERVED STREAMFLOWS AT LISTED STREAMS
(FROM USGS RECORDS)
Stream
Tributary to
Gage Location
Drainage
Area (Ml')
Maximum
Flow (cfs)
Date
Minimum
F low (cfs)
Date
Years
Observed
Number of
Observations
Canyon Creek
SFCDR
at Gem, 0.1 mile up from
Bell Gulch
18.1
817
6-8-64
9.51
9-11-77
1964-1977
9
Big Creek
SFCDR
3.5 miles southeast
of Kellogg
30.7
44.6
4-20-70
8.22
9-10-77
I97C&1977
5
West fork
Big Creek
Big Creek
Near Kellogg
5.6
44.6
6-15-71
.007
10-13-76
1971-1977
22
East Fork
Big Creek
Big Creek
At mouth
15.4
174
5-9-79
-
-
197761979
2
Montgomery
Creek
SFCDR
Near Kellogg
4.53
147
4-20-62
0
10-14-/7
1962-1979
51
Pine Creek
SFCDR
2.3 miles up from Morten
74.0
5290
12-23-64
9.84
9-1-77
196411977
6
West Fork
Pine Creek
Plrie Creek
Hear Plnehurst
10.8
63
45-6-77
0
10-9-79
1974.75.77,79
16
last fork
Pine Creek
Pine Creek
3.S miles south of Plnehurst
-
70.1
6-11-75
8
CD
W
1974,75,1.7 7
6
Middle Fork
Pine Creek
Pine Creek
9 ml southwest of Plnehurst
-
23
4-8-77
1
8-31-77
1977
12
Edit Fork
Stiver Creek
Silver Creek
at road crossing 1.5 miles
southwest of Smeltervtlle
-
-
-
.015
fl-19-77
1977
3
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153WPI-S2 SUP-17
The increase in peak flows and reduction in root strength of the denuded
soil also can result in increased soil erosion and sediment input into the
SFCQR .ind possibly increased landslide activity. Sediment transport
increases exponentially with velocity, which would be higher with higher
peak flows. Faster melts might also increase soil saturation levels
depending on soil properties, which, depending on soil cohesion with no or
little root strength, might cause landsliding activity to increase. As
revegetation increases, these effects can be expected to diminish.
2.1.3.3 The Bunker Hill Complex
The Bunker Hill facilities encompass about 350 acres of land as shown in
Figures 1-2 and 1-3 of Section 1. This includes 98 acres for the lead
smeltur, 86 acres for the zinc smelter, and 13 acres for the phosphate
fertilizer plant. The Central Impoundment Area (CIA), mine tailings and
slag 3i1e encompass another 160 acres. The Bunker Hill complex is located
in moderately rugged mountains, which are dissected by numerous well
integrated drainage channels, and surround a large, flat floodplain
(Section 2.1.2). The two main creeks on the site are Silver King Creek
(located in Government Gulch and also referred to as Government Creek) and
Bunker Creek. Both of these creeks now discharge to the SFCDR just west of
the f.lag pile.
Central Impoundment Area. The Bunker Hill mine tailings impoundment area
was originally constructed in 1926. It has been raised on a continuing
basi; using mine waste rock and other available construction materials.
The impoundment is contained in a ring dike structure which completely
encloses the CIA; The CIA area is divided into three major cells, the
central impoundment pond, the gypsum pond and the slag pile. A map of the
impoundment area is shown in Figure 1-2. The existing center dike was
built in 1974 on tailings to divide the ponds. At the present time the
perimeter of the structure is 60 to 70 ft high and has the capacity to
store a total of approximately 12,000 acre-feet of tailings (U.S. Army Corp
of Engineers 1981, 10677).
158-WP1-RT-CZLE-L
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L56wPi-i2 buP-id
The surface area of the impoundment covers approximately 122 acres, not
including the slag pile. However, the free surface water area has been
reported by the Bunker Limited Partnership to have fluctuated from 21 to 43
acres between October, 1982 and August, 1985. Robinson et al. (1980,
10181) reported that the surface water area fluctuated from 45 to 80 acres
prior to their recommended seepage reduction measures. Peterson (1985,
10748) has reported seeing the free surface of the water approaching the
toe of the dikes as late as September, 1984. Under the current wastewater
discharge permit, the Bunker Hill operators are required to report the
surface area of free water only once every two months.
Inflows to the impoundment include piped-in surface drainage from the lead
smelter and zinc plant areas, and acid mine water from the Bunker Hill
mine. Other surface drainage does not flow into the impoundment. The
quantity of acid mine water was reported by Wong (1985, 10800) to be
approximately 2200 gallons per minute (4.9 cfs). Surface drainage inflows
are not known. Other surface drainage in the vicinity of the impoundment
area consists of SFCDR, which runs along the northern edge, and Bunker
Creek, which is routed along the southern edge of the impoundment and flews
into the SFCDR west of the impoundment, about 300 feet north of the west
toe of the North Dike (see Figure 1-3). Flows in Bunker Creek are largely
made up of treated waste water from the CIA (from 40 to 100 percent,
depending on rainfall or snowmelt). The treatment plant runs 24 hours a
day from Monday to Friday. During the weekend, the CIA water level builds
up as inflows continue. The plant currently discharges an average of 2.5
to 5.0 million gallons per day (3.9 to 7.8 cfs) (U.S. EPA 1985, 10795).
Because the impoundment has no spillway, it was designed to handle a
probable maximum'precipitation event of 9.8 inches in 6 hours, or the 100
year frequency (24 hours) rainfall event of 3.9 inches with 4 ft of
freeboard (U.S. Army Corps of Engineers 1981, 10677). Seepage from the CIA
to groundwater is estimated to be about 2 cfs (Section 2.1.4.2).
158-WP1-RT-C;'-

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158WP1-S2 SUP-19
Rouse (1977, 10179) stated that "it was obvious from investigation of
various aerial photographs and from reviewing Bunker Hill files that the
Bunker Hill tailings and gypsum ponds were not the result of true design,
rather, they just happened." When this impoundment was built, no overall
plan existed concerning waste management or the geohydrological effects
that '.he pond would have on the area. Ct is well documented that seepage
from chis impoundment both into groundwater and to the SFCDR valley
adjacant to the site has been significant (Robinson et al. 1980, 10181;
Williams et al. 1979, 50231; Rouse 1977, 10179; Hawke Engineers 1978,
30051). From recent water quality data taken by EPA (Peterson 1985,
10748), it is apparent that seepage from the impoundment structure is still
significant. Several engineering reports have discussed the seepage
problem (Hawke Engineers 1978, 30051; Robinson et al. 1980, 10181) and
proposed methods to reduce seepage. These measures, which include
maintaining lower water levels in the CIA and placing mine tailings in
area'> thought to be leaking, have been only partially successful. A more
detailed discussion of the CIA and groundwater is given in Section 2.1.4.2.
Other Bunker Hill Complex Surface Hydrology Features. Other, smaller
impoundment areas are located near both the lead and zinc smelter. These
include Sweeney Pond and the main reservoir in the lead smelter complex,
and the main reservoir and settling ponds in the zinc plant area.
Wastewaters from both the lead smelter and zinc plant were routed to the
CIA before the lead smelter and zinc plant shut down. There is a very
crude collection system for runoff and wastes from the zinc plant area.
The collection ponds are plastic-lined, with obvious tears in the
plastic. Also, many pipes between these ponds are broken and there is a
fair amount of overland flow of the runoff. Towards the lower part of the
area, a sump pump is used to collect runoff water from an unlined pit. The
ultimate destination of this runoff is unknown, although it appears some of
it does end up in Government Creek, especially during high streamflows.
158-WPl-RT-CZLE-

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mine wastes from many mines situated upstream from the flats, primarily
from the SFCDR mining district. Much of the tailings have been in place
for at least 50 years. Ellis (1940, 10002) noted that in 1932 large
amounts of mine wastes had deposited in the Cataldo Flats and Mission Flats
on the main stem of the CDR and that the entire Mission Flats area of
several square miles was mostly covered with mine tailings and slime. The
wastes have also formed a delta in Lake Coeur d'Alene at the river's mouth,
19 miles downstream from Kellogg.
The main stem of the COR is much deeper and slower moving than the SFCOR.
Consequently, much of the tailings wastes discharged to the SFCDR have been
deposited in the CDR. Along the main stem of the CDR the water table is
above the adjacent valley floor during high spring runoff months.
Therefore much of the waste sediment from the SFCDR was deposited in the
surrounding farm lands and pasture during floods (Reece et al. 1978,
10004). The farmland must be drained during spring runoff to allow
cultivation.
Large volumes of fine silts have been deposited on the bed of Lake Coeur
d'Alene. Maxfield et al. (1974, 10009) found that the bottom of the lake
was covered with polluted sediments within a 900 meter radius of the mouth
of the COR, indicating that sediments from the SFCOR mining area have
traveled a significant distance out into Lake Coeur d'Alene.
2.1.4 HYDROLOGY: GROUNDWATER
In the valley of the South Fork Coeur d'Alene River the greatest
long-term water quality impaot stemming from potential sources such as
the Central Impoundment Area, Page wastewater ponds, and the saturated
unconfined mine and mill wastes on Smelterville Flats, would be to
groundwater, due to the long retention time in the valley. Therefore,
attempting to define contaminant transport to the groundwater and the
ultimate effect of contamination on humans and the aquatic environment
158-wpi-rt-c:l-:
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i?,3WPl-S2 SUP - 2 5
requires an understanding of the area's hydrogeology. This entails both
identifying aquifer characteristics that affect groundwater flow rate,
flow direction, and leaching potential, and identifying existing and
potential uses of this groundwater. Such characteristics include aquifer
type, composition, and thickness; pore space, permeability, and storage
potential; water table position; and velocity and volume of groundwater
flow.
2.1.4.1 South Fork Coeur d'Alene Valley
The physical framework of the South Fork aquifer becomes apparent from
ceophysical surveys and well logs. Seismic refraction and electrical
resistivity surveys reveal a gradual thickening of the valley alluvium in.
ci westward direction, from about 21 m (70 feet) at Kellogg to over 27 m
(90 feet) at Smelterville. Immediately west of Smeltervi1le, the depth
1:o the bedrock increases considerably, to about 47.6 m (156 feet) near
Pinehurst (Norbeck 1974, 30057), although Hobbs et al. (1965, 30084)
loted that a well drilled in Pinehurst reached a depth of 91 m (300 feet)
sefore encountering bedrock. However, just above the Pine Creek
confluence, bedrock probably occurs at a shallow depth and constricts
valley fill, forcing groundwater upward to discharge to the South Fork.
Figure 2-12 depicts cross-sections of the South Fork valley from
Smelterville to Pinehurst (Pine Creek).
Well logs indicate that alluvial sediments become coarser-grained to the
east and fIner-grained to the west (Norbeck 1974, 30057). The alluvium
consists of reworked sands and gravels derived principally from erosion
of the steep-walled mountains along the South Fork.
In the eastern part of the project area, the aquifer appears to be a
single unconfined unit of sand and gravel. Above Kellogg, these
sediments are medium- to coarse-grained and contain lenses of sandy si it
1.5 to 3.1 m (5 to 10 feet) thick (Hawke Engineers 1978, 30051). 8elow
158-WPl-RT-
2-44

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2400
2300
2200
2)00
2 2000
<
>
U
w 2400
2300 -
2200 -
2100 -
2000

Valley Cross Section at East End of Paga Pood
	1000 tot
100 200 300m«ttfs
5 00
1
rr
\ IM'

Valay Croas 3actton at Ptnc Creak
725
700
675
650
625
-	725
-	700
-	675
-	650
-	625
-	600
m
<
>
I
Oapttt Point
* ftMtettvtty Oapth Point
2.5: 1 v«rt>eal Exaggeraten
Figure 2-12. CRQ$S-SECTIONS OF THE SOUTH FORK
COEUR D'ALENE VALLEY, IDAHO
:-js
isa-APt ar	i

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L5 8*.- 1-52 SUP - 2 6
Kellogg, clayey silt interrupts the vertical continuity of the sand and
gravel fill and forms an aquiclude (impermeable unit) separating the
ailuvium into two well-defined aquifers. Logs of wells in Smeltervi1le
Flats and near the Central Impoundment Area indicate the upper sand and
gravel unit here ranges from 3.7 to 11.6 m (12 to 38 feet) in thickness
(Figure 2-13). From Kellogg to the western boundary, the lower gravel
unit pinches in from 13.7 m (45 feet) to less than 1.5 m (5 feet) in
thickness. The clayey silt unit apparently thickens in a downstream
direction, becoming wedge-shaped, and probably represents lacustrine
deposition near an inlet to glacial Lake Coeur d'Alene. Less than 1/2
mile south of the logged wells, the geology changes to a sequence of red,
brown and gray clays interlayered with well-packed gravel. Available
d.ita indicate the clay horizon extends across the entire width of the
v.il ley.
The water table defines the seasonal upper boundary to aquifer thickness
for the unconfined aquifer. Below Kellogg the thickness of the confined
aquifer varies only with geology and not with season.
Dita from Rouse (1977, 10179), Hawke (1978, 30051), and the Bunker
Limited 1985 NPDES application permitted accurate assessments of the
aquifer thickness in the vicinity of the CIA. Hydrographs of three Hawke
monitoring wells show the unconfined aquifer thickness has varied from
7.6 to 9.5 m (25 to 31 feet) in the period 1980-1984 (Table 2-8); Rouse
data indicated a minimum saturated thickness of 5.5 m (18 feet) in
1976. On the other hand, data show the confined aquifer thickness vanes
from 1.5 to 13.7 m (5 to 45 feet), increasing in the upstream
direction. Any interconnection between the unconfined aquifer and the
(semi-?) confined aquifer remains unknown. Near Pine Creek, shallow
bedrock may either terminate the confined aquifer or provide via
fractures a conduit for confined flow to recharge the unconfined aquifer
and the-river.
158-WP1-RT-C:
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153WP1-S2 SUP-39
2.1.5.3 Air Qua!ity
Air quality in the project vicinity is routinely monitored by the
Division of Environment within the Idaho Oepartment of Health and
Welfare. Particulate monitors (total suspended particulate [TSP| high-
volume samplers) are maintained at Kellogg (Silver King School and
Medical Clinic), Osburn (radio station), and Pmehurst (Elementary
School); a sulfur dioxide (SO;?) monitor is maintained at the Silver King
School as well. The particulate samples collected are routinely analyzed
for lead content.
Overall emissions--of sulfur dioxide, total suspended particulates, lead,
and other materials--were strongly affected by two factors at the 8unker
Hill lead and zinc smelter complex during times of operation: production
rates and processing operations, and controls on air emissions that were
in place and operating at the time of a particular emissions survey.
Plant production rates increased in the late 1960s and early 1970s when
the older downdraft ore roasting operation was replaced by an updraft
sintering process; stack lead emission rates measured by the company
increased at about this time from historic levels of some 10 tons per
month to about 15 tons per month (T/mo). The 1972 augmentation of the
blast furnace increased production and resulted in stack lead emissions
measured by the company of about 20 T/mo. In 1973, two of seven baghouse
filter units were incinerated in a fire; a third was shut down for
routine maintenance and was inoperable for about six months. Figure 2-16
shows total lead smelter main stack particulate emissions, expressed in
tons per month, from 1965 through 1974, encompassing the period of the
baghouse fire based upon company data (BLP AP-053-4-a, 11165). Emissions
of material in February and March 1974 were more than five times as great
as average emissions for the preceding period.
Figure 2-17 shows monthly mean ambient lead concentrations in Kellogg
from 1971 to early 1975 from state ambient air quality monitoring data;
158-WPI-RT-CZLE-l
2-66

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<60
140
120
E 100
- 80
E 60
= 40
1965
I 1966
iiwMim
1967 I 1968	I 1969 I 1*70 I
UM^awawJ
t
mi
Not* i " miuinf datj
1T)2
1973
1974
Souicc BLF Fil* APOS3-4-* 1116S
Saved on Bucket Hill Co dau for
suck emiuiom only.
Figure 2 16 TOTAL PARTICULATE EMISSIONS
LEAD SMC L IT R MAIN STACK. 1965-l'J/4
I&6 WP1 HT (/It I
2-U7

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predicted from these experimental observations to travel over high
terrain along the south edge of the valley, and at the lead smelter under
south winds, which were calculated to carry plumes along the valley to
the confluence of the north and south forks of the Coeur d'Alene River,
thence north.
IDHW (1975, 10752) concluded that, at that time, airborne lead was the
primary contributor to elevated blood-lead levels. The report analyzed
lead data from periods both prior to and following the October 1973
baghouse fire at the lead smelter. Average lead content of TSP samples
in the period immediately after the fire (October 1973-March 1974) was
some 16 percent, approximately twice the average lead content from the
period just preceding the fire (October 1972 - September 1973). It was
further suggested that such short exposures may represent as great a
dosage risk as longer exposu-es. Exposures were highest in the winter of
1973-1974, during the period when portions of the incinerated baghouse
were not in operation.
Ragaini et al. (1976, 10035) carried out chemical analyses of soil and
vegetation samples, and air sampling filter data, to discern source
contributions in the smelter area. Their analysis did not include source
sampling, and was not able to definitively allocate the relative source
strengths in the samples. On the basis of factor analysis, they
attributed likely origins to various elemental concentrations. Ragaini
et al. attempted to draw conclusions about the origins of the various
elemental factors, based on assumptions and "logic" about characteristics
of major source areas. They concluded the various constituents came from
these sources:
• Lead smelter - Elements with high fractions of small aerosol
particulates, showing decreases in concentration with soil
depth: major occurrences of lead, arsenic, cadmium, antimony,
selenium, zinc, mercury, silver
158-WP1-RT-CZL-:
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158WP1 S2 SUP-45
•	Zinc plant - Elements with high aerosol fractions that decrease
with soil depth: zinc
•	Soils origin - Elements with higher large-particulate fractions
and no decrease with soil depth (none of the contaminants of
concern occurred)
•	Tailings - No correlation between lead and arsenic; arsenic
decreases with depth, and has a higher small-particle fraction
in the tailings than in soils.
2.1.6 VEGETATION AND REVEGETATION
2.1.6.1 Development of Present Vegetation
The vegetation of the study area has been severely modified over the past
one hundred years by a combination of mining activity, logging, forest
fires, and smelter emissions. Areas which were originally in dense
fore5t have become barren or sparsely vegetated shrub communities. SCS
(1974, 10806) identified over 12,000 acres of moderately to severely
eroded and sparsely vegetated land in and near the project area. The
Bunker Hill Company, as part of a revegetation effort beginning in the
earlv 1970s, identified 18,000 acres requiring reforestation. About 80
percent of the 18,000 acres had been damaged by smelter emissions or
(iiinng, and the remainder required revegetation for other reasons, such
as paor regeneration after timber operations (Pommerening 1986, 10805).
Although reforestation efforts have been conducted on about 5000 acres
with reportedly good success (Pommerening 1986, 10805), much of the
project area remains sparsely vegetated.
The original vegetation of the area was primarily conifer forest. Major
species in the area were ponderosa pine and Douglas fir on the warm
2-80
158-WP1-RT-CZLE-1

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153WP1-S2 SUP-54
trees and grasses closest to the zinc plant were killed during the study,
apparently by high zinc concentrations m the soil, and/or SO^ injury.
2.2 HISTORY OF BUNKER HILL COMPLEX
2.2.1 OWNERSHIP
The approximately 350-acre Bunker Hill complex is composed of an
inactive, integrated mining, milling, and smelting complex which includes
the Bunker Hill mine, a mill and concentrator, the lead smelter, an
electrolytic zinc plant, a phosphoric acid and fertilizer plant, a
cadmium plant, and sulfuric acid plants. Mining and milling activities
have been conducted at the complex for 100 years. Phil O'Rourke and Noah
Kellogg filed their mining claim on the Bunker Hill lode on September 10,
1885; a 100-ton mill commenced operation on July 20, 1886 (Kellogg
Centennial Committee 1985, 10841). Since then, millions of tons of ores
have been mined in the valley and processed through the complex. The
complex was closed in 1981 because of poor economic conditions; before
then, the major products were lead, zinc, cadmium, silver, and gold (and
their alloys, including dore metal), sulfuric acid, phosphoric acid, and
four grades of fertilizer. The Bunker H111 complex typically employed
about 2000 people, and produced roughly one-fifth of the refined lead,
zinc, and silver in the U.S. (Kiellng 1985a, 10758).
The Kellogg-based Bunker H111 and Sullivan Mining Company, incorporated
in 1887, was the original owner and operator of the complex. The Bunker
Hill and Sullivan changed its name to the Bunker Hill Company in 1956.
In 1968, the complex was purchased by Gulf Resources and Chemical Company
of Houston, Texas, which operated it until its closure in late 1981. The
complex was purchased on November 1, 1982, by its present owners, the
Bunker Limited Partnership, which has its headquarters in Kellogg.
Although the current owners have not reopened the complex, they did some
on-site cleaning and held preliminary meetings with the State of Idaho
L58-WPI-RT-C:_ _
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LS8WP1-S2 SUP-55
and EPA regarding their plans for the complex. Presently, Bunker Limited
i;. salvaging and selling replaceable equipment {a major auction was held
m October 1985) and attempting to attract prospective lessees to the
complex. On May 22, 1986, one of the Bunker Limited Partnership partners
announced that the smelter would not reopen. Currently, the only
facilities in operation are the 8unker Hill mine pumps, the wastewater
treatment plant, and the zinc concentrate dryer (leased to another mining
company). The Crescent Mine (silver) and the mill's Crescent Circuit
(receiving ores from the Crescent Mine outside the project area) reopened
n late 1983, and employed about 70 people, producing roughly 500,000
ojnces of silver concentrates, which were shipped to Belgium for further
refining (Bond 1985a, 10531; Kieling 1985b, 10759). The Crescent Mine
and the mill circuit closed on May 30, 1986, due to depressed silver
prices.
2.2.2 SITE HISTORY
The Bunker Hill and Sullivan Company was originally involved only in the
mining and milling of lead and silver ores from local mines. The first
mill was built in Milo Gulch in 1886. The present mill was constructed
n 1912. Froth flotation was installed at the mill in 1938; improvements
vihich expanded production followed in 1941 and 1947. Cyclone separators,
which removed the coarse fraction of the mill tailings for use as sand
backfill to the Bunker Hill mine, were installed in 1961. Prior to
closure in 198L, the mill had a throughput capacity of 2500 tons per day
(Peterson 1975, 10671).
Construction of the lead smelter began in 1916, and the first blast
furnace went.on line on July 5, 1917. Prior to 1917, local concentrates
*ere sent to the Tacoma smelter in Tacoma, Washington. The lead smelting
process remained essentially the same until 1970 when the downdraft ore
roasting operation was replaced by the Lurgi updraft sintering process
and associated sulfuric add recovery plant. In 1972 the blast furnace
L58-WP L-RT-CZLE-.
2-90

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L53WP1-S2 SUP -56
was extended to accommodate increased production rates. In 1977 a 715-
foot stack was added to the smelter to facilitate pollutant dispersion.
The smelter has a capacity of 305 tons of metallic lead per day (EPA
Region X, Air Programs Development Section 1984, 10097).
The electrolytic zinc plant began production on November 6, 1928. The
plant was the first commercial refinery in the U.S. to produce 99.99+
percent purity zinc. The plant had an initial capacity of 50 tons per
day. It was enlarged to 120 tons per day in 1937 and 160 tons per day in
1948. An additional unit was added in 1963; in 1967 the plant was
finally enlarged to its pre-closure capacity of 310 tons per day. Two
sulfuric acid plants were added to the zinc facilities in 1954 and 1966,
and one sulfuric acid plant was added to the lead complex in 1968 to
convert processed sulfur dioxide (SO2) to high-grade sulfuric acid for
use in the electrolytic process. A 610-foot stack was added to the
facilities in 1976.
The phosphoric acid and fertilizer plant, a joint venture with Stauffer
Chemical, was constructed in I960. Phosphate rock was delivered via rail
from Utah. The primary products from this plant were phosphoric acid and
pellet-type fertilizers of varying mixtures of nitrogen and phosphorus.
Phosphate rock, anhydrous ammonia, and sulfuric acid were the chief raw
materials used to produce the phosphoric acid and the by-product, gypsum.
Initially, all liquid and solid residues from the complex were discharged
into the South Fork Coeur d'Alene River (SFC0R) and its tributaries.
Periodically, the river flooded and deposited the waste material,
containing zinc and other he^/y metal sulfides, onto the valley floor.
Leaching of thQ deposits has resulted in the addition of heavy metals to
the river, and to the groundwater, especially during periods of
precipitation or in areas where water is ponded on the valley floor.
158-WP1-RT-C:.
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158WP1-S2 SUP - 57
The Bunker Hill Company was one of the first mining companies within the
d strict to control the discharge of solids to the river. The first
rftained materials consisted solely of mill tailings discharged into a
snail tailings pond (later abandoned) near the present east end of the
Ctmtral Impoundment Area4 (CIA), and lead smelter slag deposited at the
present site of the slag pile. After the small tailings pond was
abandoned, it was later reclaimed and reprocessed for additional metals
with resultant tailings eventually deposited in the CIA (Tierney 1985,
13002). Ponds were constructed to settle mill solids and discharge the
liquid directly to the river. This process was discontinued when the
Central Treatment Plant (CTP) was constructed in the early 1970s to treat
the decant. However, considerable seepage from the CIA still finds its
way to the SFCOR. The Bunker Hill Company had investigated seepage from
the CIA and had attempted to seal the CIA by discharging concentration
slimes into the CIA and gypsum ponds, later surveys have shown that the
leakage has not been controlled. The success of subsequent attempts to
?eal the CIA has not yet been evaluated. The CIA started receiving mine
drainage water in 1965. From 1970 to 1974, gypsum from the phosphoric
cicid and fertilizer plant was discharged Into the CIA. In 1974 a
dividing dike was constructed across the CIA to provide a separate area
for gypsum discharge. The decanted contaminated water was returned to
:he phosphate plant. The zinc plant and smelter began discharging into
:he CIA in 1974 (Hockberger 1984, 10144). The decant from this portion
of the CIA is piped to the CTP located southeast of the CIA, adjacent to
the mill. The treated water from the CTP passes through a reservoir
prior to discharging into Bunker Creek.
d For a detailed discussion of the Bunker H111 CIA construction
history, see EPA Office of Enforcement 1977, 10133.
158-WPl-RT¦
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formerly also used for fire protection, but these wells have been
contaminated from old mine and mill tailings deposited throughout the
valley floor. Zinc concentrations in water from the South Fork wells
were reported in a Bunker Hill Co. memorandum of February 4, 1977 to
range from 14.7 to 42.0 mg/i zinc (in January 1977), and the use of the
South Fork wells has been discontinued (BLP File WP-024 Source Point
Central Impoundment Area, 11164).
2.2.2.1 Regulatory History
For most of its operating life, the complex had few or no controls on
atmospheric emissions, solid waste disposal, or wastewater treatment.
Consequently, past practices at the complex have contributed to the
deposition of hazardous substances (primarily particulates containing
heavy metals), throughout a large area of the valley.
In the early 1970s public concern focussed on heavy metal emissions and
contamination of surrounding soils. Levels as high as 2.5 percent lead
were observed in some barren areas (von Lindern 1982, 35204). Both the
lead and zinc plant stacks used baghouses to capture particulates.
However, variations in controls, changes in levels of plant operations
and operating equipment performance, and other factors allowed quantities
of particulates containing heavy metals to escape from the stacks.
The effectiveness of the baghouse was significantly reduced by fire in
1973, and remained low during the six months before the baghouse was
repaired. Emissions of about 20 to 100 tons of particulates per month
containing 50 to 70 percent lead were reported, compared to about 10 tons
per month prior to the fire (Figure 2-16). The immediate effects of
increased lead emissions and higher lead-in-air content showed up in
local children. By February 1974, symptoms of lead poisoning were
reported to public health officials. Oetailed epidemiological studies
were subsequently conducted which demonstrated that a significant number
of the children had elevated blood-lead levels. The same studies
2-93
L58-WPL-RT-C2L-:

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158WP1-S2 SUP - 59
identified the lead smelter as the major source contributing to the undue
lead absorption.
The disposal of solid waste materials from the Bunker Hill complex has
¦lontributed to the contamination of local surface waters and groundwater
(CH2M Hill 1983, 10164). As discussed, the 160-acre CIA was the main
jisposal area for solid and slurry wastes of varying quality and
quantity. In addition, other smaller areas have been used in the past to
store concentrates and by-products prior to sale, as well as to dispose
of unwanted solid wastes. The CIA is constructed on the alluvium of the
SFCDR floodplain. The dikes are constructed of mine waste rock and jig
tailings. The CIA has been identified by numerous EPA investigations as
a significant source of discharges which contribute heavy metals,
fluorides, and phosphorus to the South Fork and its tributaries. These
conditions violate water quality standards and have continued, although
to a lesser extent, since the complex shut down in 1981. The EPA has
shown heavy-metal increases due to seepage in that reach of the river
running parallel to the CIA. Significant loadings of heavy metals have
also been reported in tributaries of the river, which typically accept
runoff from the complex, during periods of precipitation and high water
(CH2M Hill 1983, 10164). These findings have been the basis for repeated
compliance orders and Section 308 requests from EPA under the Federal
Water Pollution Control Act, and for the filing of civil action suits
resulting in the assessment of substantial fines by federal courts in
Idaho.
2.2.3 PROCESS OPERATIONS6
2.2.3.1 Mining
Mining is conducted over a vertical distance of approximately one mile
^ Adapted from Peterson, 1975, 10671; and von Lindern 1982, 35204.
158-WP1-RT-
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158WP1-S2 SUP-65
Wastewaters from the zinc plant were piped to a settling pond located on
the east side of Government Gulch. The pond discharge was piped to the
CIA. A materials flowchart for the zinc plant is given in Figure 2-19.
2.2.3.8 Phosphate Plant
In the production of phosphoric acid, sulfuric acid produced at the zinc
plant reacted with phoshate rock (shipped from southern Idaho or Wyoming)
to produce phosphoric acid and gypsum, a by-product. The gypsum was
separated by filtration and transported to the gypsum pond located in the
CIA.
2.3 CHRONOLOGY OF EVENTS
1886	- first mi 11 built
1887	- Bunker Hill & Sullivan Mining Co. incorporated
1912 - present mill constructed
1916	- construction of lead smelter began
1917	- first blast furnace at the lead smelter went on line
1928 - electrolytic zinc plant began production
1928 - Bunker Hill tailings pond constructed
1937	- zinc plant enlarged to 120 tons per day
1938	- froth flotation installed at mill
1948 - zinc plant enlarged to 160 tons per day
153-WPl-RT-CZLE-!.
2- 101

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153WP i-S2 SUP-66
1954 -	first sulfuric acid plant added to zinc plant
1960	-	phosphoric acid & fertilizer plant constructed
1961	-	cyclone separators installed in mill
1963 -	additional unit added to zinc plant
1965	-	CIA started receiving mine drainage water
1966	-	second sulfuric acid plant added to zinc plant
1967	-	zinc plant enlarged to current capacity of 310 tons per day
1968	-	sulfuric acid plant added to lead smelter
-	complex purchased by Gulf Resources & Chemical Co. (effective
6/01/68)
197C - downdraft ore roasting operation replaced by Lurgi updraft
sintering process and associated sulfuric acid recovery plant
-	gypsum from the phosphoric acid & fertilizer plant began
discharging to CIA
197;? - blast furnace extended
197 3 - severe fire in main baghouse
-	extensive study of lead smelter stack and fugitive emissions
1974 - 1 dividing dike constructed across CIA to provide separate area
158-WP1-RT-CZL: -1
„ 2-102

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0499s-22
problems in the SFCDR	drainage. Therefore another significant source of
heavy metal pollution	of the SFCDR may be washed-off heavy metals
deposited over the 21	square miles of the project area. Hillside
sediments transported	by runoff are contaminated as well.
3.3.3.2 Comparison of Mater Quality Over Time
In order to assess the change in water quality over time, water quality
constituent concentrations which have been monitored sporadically from
1966 to 1984 at the water quality stations shown in Figure 3-18 were
compiled and summarized using the EPA STORET system. Tables 3-18 through
3-32 present yearly means and overall averages of the following water
quality parameters respectively: total antimony, total arsenic, total
cadmium, total chromium, total copper, total fluoride, total iron, total
lead, total manganese, total mercury, total selenium, total zinc, pH,
total hardness (as CaCO^), and total sulfates. The measurements were
taken mostly during low flow periods (September and October)., which would
normally be when the highest concentrations of most constituents are
observed. The last few years of data (1979, 1980, 1982, and 1984) were
all taken during low flow conditions. The yearly averages reported in
these tables are in most cases determined by very few measurements taken
over a very short time. Therefore, any conclusions drawn from them are
affected by their limited description of actual concentrations. However,
some conclusions can be drawn from them as some very significant trends
can been seen. Short term water quality problems (i.e., a spill or storm
runoff) were probably not picked up by this monitoring.
For many constituents, the most significant reduction in concentrations
of heavy metaTs in surface runoff since 1970 (the oldest data set
available) occurred after the shutdown of the Bunker Hill complex in
1981. A number of constituents showed improvement (especially on 8unker
Creek) after treatment began on CIA effluent releases and also when the
zinc plant and smelter effluents were routed to the CIA rather than being
discharged directly to the SFCDR and its tributaries (as had been the
3t190
158-WP1-RT-CULW-i

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IABIC 1-18
n«r oescavcD wan ODMXNnurioNS or ioiu mitinonv (la p#/i> *r nc lisiio staiions'
	»Mf			fatal
SUtlc*2	1966	1969	1970	1971	1972	197*	19/4	1975	1976	1979	I960	1902	1984	Av«r*9»
1)1104
vcn at Bride*
it«« ai| Croat
40.0 (II
4.0
(II

10.0
(41



19.0
(41


2.9
(11
1.0 (II
10.4
(191
mioe
srcw at Bunfcar
Brldpa, Halloa
«0.0 (II
7.6
ai
4.9 (21
4J.5
(61
26.7
(III
II.1 (41
18.0
(6)
8.0
(91
2.7
(61
17.4 (II
18.9
(921

>• Naar CIA




4.0
(II
9.4
(201
1.7 (91
2.0
(71
4.0
(II
2.9
(41
0.7 (1)
9.1
(491
13 MOO
STCOR *4J*cant
to CIA






29.4
(91

18.0
(11
0.0
(Jl
2.9
(II

19.1
(161
I»H1
VCCR ¦bn*
ln*»f Croak


















195169
8u*ar Croak
BO.O (II
IJ.O
(ii
17.2 (91
19.8
(61
18.0
(61
7.9 (71
84.9
(41
10.9
(41
2.9
(41
0.90 (2)
22.9
(161
miti
Sll»ar Kit*
Crmmk
100.0 (l>
86.0
(91
929.S (01
29.0
(61
90.1
(101
6.9 (41


88.0
(II
2.9
(41
0.90 (7)
117.1
(411
ISIIIO
MOT ufntrMa of
Saoltorvlllo flats
IJO.O (II
21.9
(91
/.6 (91
19.)
1161
29.4
(121
9.0 (41
29.9
(61
6.7
(61
2.9
(71
12.9 (11
29.7
(881
1)1)1)
STCOR atx»a
flna Croak

H.O
(41

46.7
(61



21.0
(61
6.4
(31
2.9
(41
10.0 (2)
21.2
(271
131207
rina Cradi

loi.a
(II

4.0
(21
6.0
(II
6.0 (II
19.0
(21
6.0
(II
9.0
(II
10.9 (II
26.1
(III
191021
yen at
CmvIIIo
110.0 (II
49.4
(161
6.0 (91
>1.0
(71
20.0
(61
9.9 (41
20.8
(91
9.6
(91
2.9
(II
9.8 (Jl
24.9
(991
191019
an at
Im>I 1 lo
29.0 (II
1.1
(II
1.0 (41


1.0
(21
0.9 (21
2.0
(41
2.0
(II
2.9
(11
0.79 (21
2.9
(101
djoii
COM at
Catal<*>

40.)
(41
1.6 (/I


4.0
(21

7.0
(41
2.0
(II
1.9
(11
1.4 (21
9.9
(211
*	Vilim In pywttwwi Indlcttv how mmf miurtd concentrations Mm wt«d to cilculiN tha *»*n concantrations glvtn.
*	Station locations glvan In Flpura J-IS.
IV0-MRl Rr-Cuiw-|

-------
TABIC 5-19
VEAAT 08SCRVC0 KAN CONCCNnUflGNS Of fOfAL ARSCNIC (In MO/<* *' ™E llStlO SIAIICMS1
T—r
Station'
1966
IW9
1970
1971	1971
197)
1974
1975
1976
1979
1980	1981
fatal
Avnraga
15)104 srail at Brldga
•boo* Big Cradl
•5)100 STCOR at 6unA»r
•rld^a, Rallog
mt CIA
15)600 srcn adjaoant
ta CIA
15)562 tfOM atiooa
vO
u
153165
19)151 Sllvar Una
Creak
15)110 SfCDR upitrM* of
faaitorviiu run
15)))) SfCDR
flna Cmfc
15)107 Plan Creak
i)»» yen at
CnMllla
15)019
OK at
(aavllta
19)018 COM at
Catal*>
5.0  1.0 (II
1.7 (41
4.0 14)
1.5 O) 0.50 (1)	7.5 (15)
>1.0 (I) 1.0 (4) 6.5 (It 75.1 (Il> >6.5	(12)	>.5 (4)	5.8	(6)	2.0 <5>	2.9	(6)	8.1 <)>	15.8 (54)
11.2 ())	29.2	(20*	74.1 (9)	58.0 ( 7)	5.0 (I)	57.8	(4)	46.4 ())	44.1 (47)
)1.9	(9)	8.0	(It	2.0 O)	2.9	(I)	21.1 (16)
29.8 (6)	29.1	(II)	7.8 (6)	9.2	(10)	4.1 (81	2.5	(7)	8.6 (4)	IS.9 (52)
1460.0 (1) 2.0 (1) 42.8 (51 22.9 (10)	52.0	(6)	21.0 (2)	14.0	(4)	9.5 (4)	5.1	(4)	1.4 (2)	60.7 09)
58.0 (I) 42.0 (I) 201.0 (8) 20.0 (10)	29.4	(10)	10.8 (4)	92.0 (I)	2.5	(4)	0.55 (I)	57.7 (41)
144.0 (I) 6.0 (4) 11.2 (5) 11.0 (4))	)7.J	(12)	7.5 (4)	7.5	(6)	4.9 (6)	2.5	(7)	8.) ())	14.2 (91)
2.0 (I)
10.4 (16)
6.0 (6) 5.6 (5) 2.5 (4) 4.9 (1)
6.7 (6) >.2 (5) 2.5 (4) 0.50 (2) 2.0 (2) 1.0 (2) 2.0 (4) 2.0 (I) 5.5 O) 5.0 (2)
9.1 ()) 1.0 (4) 4.9 (7) 1.4 (5) 5.0 (2)
6.4 (18)
2.0 (I)	0.60 (I) J.O (I) 1.0 (I) 2.0 (2) 2.0 (I) 2.5 (I) 0.50 (I) 1.7 (9)
45.) (7) 11.5 (8) 8.0 (5) 6.1 (7) 15.8 (6) 9.0 (4) 5.2 (5) 2.4 (5) 2.5 (7) 2.9 O)	14.0 (58)
4.6 (»)
2.0 (4) 2.0 (I) 2.5 ()> 0.60 (2)	5.1 OO)
' lalim la paranthaaaa ladlcat* how aany aaaiiarad eonoantratloti nan u«a4 to calculate lha aaai concentration* gl«a
' Station locations gl »an la figure J-18.
CPA Or Inking ttetar Standard (Prlaary SUntanoo) 50 yg/1
(PA Haiardwi Matta Standard (CP fcaalclty) 5000 pg/i
158*1 -RI-CUV-I

-------
TABIC J-20
TCAf&r OBStRno mut cmccNnurioMS or toiai cadmium ii» h»/i> ai iw nsrto sfaiicns1
Fotal
Station1	IW«	1969	1970	1971	1971	197)	1974	1971	19/6	(979	1980	1981	ISW4	l 41.6(11)
11)600 Sicn	20-1 (61 20.0 (9) 20.2 (61 IB.7 (» 16.0 (6) 10. > (I)	19.2 (111
to CIA
|))S62 SrOM atmo	M-9 (12) 17.9 (I) 20.1 (10) 17.1 (10) JO. I (II) 14.1 17) 10.) (4) IB.B (61)
Buyi* If Crwk
11)161 Bmfcar Craak	10.0 (11 121.0 (21 207.0 (1) 62.1 (101 170.0 (6) 112.0 (4) 94.1 (4) 141.1 (4) 2B.4(4> 11.8 (1) 110.0(41)
II)112	SIl»or Kino	>100.0 (I) 780.0 (I) 811.7 (6) 1166.0 (81 1020.0(101 1771.0 ( 44) 1171.0 (B)	1216.0 (I) 17.8 (1) 28.7 (1) 1184.0 (861
CtmH
111110 SUM i(n«M o»	141.0(1) 1*7.) (10) 171.7(711 41.6(4)) M.S (12) 108.1(6) )).)(6> 14.4(7) 11.0(7) 18.6(1) ID.0II10I
Mtir«lll« flat*
III)1}	UXOR above	2)9.0 (4)	1J.6 (10)	48.1 (6) 11.0 (1) 11.9 (4) 27.7 (1> 67.4 (11)
Pin* Craat
111107 riwCra*	1.0 (1)	1.0 (21 1.0 (1) 1.0 (1) 0.61 (2) 0.20 (1) 0.10 (11 0.40(1) 0.70 (10)
HMD ycot at	110.0 (I) l».0 (2) I04.0 m lie.O (I6> 64.B (!) 29.6 ( 71 76.7 (6) 98.0(61 99.2 (1) 16.4 (II 16.7 (7) 21.) (1) 78.1 (711
(u»lll«
11)019 CM at	10.0(1) 1.1(2) 17.7(6) 4.1(101 1.11(4) 1.0(2) 4.0(2) 1.0(4) 0.)1(«> 0.2(11 0.1 ()) 0.1(1) 4.1(41)
(narlll*
•1)018 aw •»	17.0(1) >2.0(1) 14.7 ()) 4).0 (I) 11.8(71 B.S ()) 21.0(1) 11.0(4) 6.8(4) 11.0(11 !.)()) 9.4(1) 11.1 (M)
CaUldo
' Vilun In pcrtnllmM	ludlcift hew MA|r mtwW oono*n1r«ll«ni wf< HWd to calculato tho win coMmlrtllont glvon.
' Station location* fllvo* la FI pur* 1-18.
(PA Or Inking Mir Standard (primary Subitanoo) 10 yg/1
(PA Hiurtoi Wait* Standard (CP faalclty) 1000 |>g/l

-------
TABU 5-21
YtMLT CBSCRttOWAN OCrCtNIKAlIONS Of TOTAL QKMIIM (In |tg/l> AT TIC HSItO STATIONS*
SUIIan'
1966
1969
19/0
19/1	1971
I9M
1914	19/5
1916	1919	1980	1982
1984
Total
A»*r*0a
If 1104
onoa
SfCOR at BrIdp*
itoM Big Crtak
SfCOt at Bunfcar
BrIdB*. Hallof
11)600
CIA
van
to CIA
IMJ62 STCIM atova
Bunfcar Craak
1)1169
1)11)1
Bunkar Craak
Sllvar King
Craak
iDiio van ifntrM «i
SaaltarvlI la riatt
1)1111
I)>20r
II)011
I)»I9
II)016
srem
flM Craak
rim Craak
STOM at
EmvIII*
COR at
laarllls
CO) at
Cat a l*>
6.0 III
1.0 (It
1.0 «l»
1.0 (II
9.0 (21 1.11 (1) 2.0 (II
IS.0 (II
100.0 (I) 10.0 (I)
ll.O (II 6.0 (21 10.0 (II
11.0 (I) 901.0 (21 0.62 (91 6.0 (II
M.O (I) I./) (41 9.12 (61
M.O (II 10.0 (21 9.0 (21 4.0 (II
0.50 (21	I.) (II
0.50 (II	2.6 (91
0.50 ())	0.90 ()l
0.)0 (41	0.90 (41
O.M (21	6.)) ()l
1.0 (II 0.90 (21	22.4 (91
0.90 ()l	9.21 (/I
0.90 ( 21	0.90 ( 21
0.90 (II	0.90 (II
0.90 ()l	109.9 (221
0.90 (21	9.0 (141
0.90 (2)	9.22 (91
' Tallin la paranthntl Indlcata Imm aaiy i
' Station locations fllla Flgurm 1-IB.
turtd eonoantratlon* xra HMd to ctkultN thi mm coocw»tf flout given.
CPA Drinking VftUr Sf«Mterd 
-------
vtarlv oesfBrto w«n ooNCCNiiwiioris or toiu otttr (in w»/i> At nc usrro srAiiws'
T—r
sutlo*

IM
<969 1910
1971
1971
I9M
19/4
i9r>
1976
1979
I960
1982
I9B4
«...
IMIM
vam *t vi dp*
Ala Cr**h


77.0 (1)
17.0 (II

4.0 (4)


7.0 (4)

7.6 (11
2.0 (21
1.69 (It)
IUI0S
STCOR •« 0unt*r
Brldgn, Hallog


16.0 (2)
12.8 (•>
3.0 (21
4.8 (191
6.f iiji
;;;
"1 »¦
8.1 (61
«.l (61
1.4 (I)
6.88 (611

< Mmt CIA





2.8 (81
18.0 (201
10.1 191
1.1 (II
6.0 (II
1.1 (41
1.1 (1)
10.4 (921
tIMOO
STCW xU«e«.«
to CIA





4.2 (6)
«.• (9)

6.0 ()l
19.0 (11
0.20 (II

6.8 (22)
IMS61
sran itow
Bunk*r Crat





4.9 (III
9.1 (III
9.8 (6)
9.9 <101
7.6 (III
1.9 (71
I.I (4)
9.1 (COI
15)161
Bunker CnA

Z9.0 (II



II.) (21
79.0 (6)


28.0 (1)


21.2 (101
imim
Slltar King
CrMt

IM.O (l>
IM.O (II


».0 (21
106.0 (9)





100.0 (811
1)1110
srcn upitrM or
Snilmrillf flats

l.U («»
14.0 (It
18.0 (l>
8.0 (II
9.0 (91
8.9 (71





9.2 (221
)}}}}}
yew «bM
rin« crtti



18.0 (II

12.9 (21






14.1 (J)
immi
Pin* CrMt













t»K>»
VO» •!
tn*»lll*
64.0 (1)
8 # (l«>
11.1 (9)
8.6 (101
10.0 (!)

9*.o m


20.0 III


18.9 (40)
1)1019
an it
[n*«111*
>.0
II.I (61
1.4 (91
I4.» (II)
4.9 (4)
4.9 (21
2.0 (21
>.0 121
1.0 (41
1.0
0.71 (21
2.2 (21
6.* (411
151010
cot •«
18.0 (II
>•.9 C«)
8.3 II)
0.6 (8)
2.2 <21
9.0 (11
9.0 (2>

1.9 (41
9.0 III
0.20 (II
2.9 (21
8.0 (171
Mil*
' lalon la	Indie*!* how amy —nm ad conc*ntr*ll«nt m>« in«d to cilculiU IN* asm «oncantr*tlo%> glvavi.
' fiction loc«flm» flw In Flgurv 1-16.
CPA Orlnklne ««t«r st»*ivd (Secondary Subtlane*! 1000 v9tl
IW-WPI-RI-CW.X-1

-------
TAfiLt HJ
runr cbscrho km conchirmions or roiu riumioc u» «b/ii at nc iisnn siaiiok*
StalIcn*
1969
19)0
Taar
1911
19/2	1911
19/4
19 n
19/6
19/9
1980 1981
1984
total
Avaraga
1)1104 VCDR at Brldpa
• Big i
1)1108 VCOR at Bunfcar
BrldB*. Rallof
CIA
I)>600 SfGOR maCMl
to CI*
i!])6i srcm
1)116)	Craah
l)II)> Sll»»r King
Crmti
ipiuo sraii <4m(m o<
MNnlll* Flat*
Dim srcm
riM m
1)110/ riM CrMt
Dion srcm at
IwiliU
1)1019
CM at
ImvMU
0.0) (I)
0.0) III
l)Mlt CM at
Cataldo
0.64 (I)
0.0) (It
I.I (It
1.6 (It
0.0) (II
1.1 (It
0.0) (II
0.B4 (II
0.04 (41
0.01 (II 0.04 (I)	0.04 (l>
0.04 (61	0.04 (M 0.01 (»)	0.04 (It	0.01/ 	II.) (1)	11.6 (4)1
. 0.0/ ())	O.IO <)> 0.0/ (l>	0.00 (/>
1.1/ (10)	1.12 (ll> O./l (/I	O.M (41	1.04 (121
l).0 (41	1.6 (4)	1.9 (4)	0.10 (21	).)6 (l)>
1.4 (I)	0.» (4)	0.64 (I)	0.6) (/I
1.1 (6)	I.I (/)	I.I (61	O.M (1)	I./I (III
2.9 (6)	I.I ())	0.00 (41	0.)/ (!)	1.60 nei
0.01 <21	0.02 (l>	0.02 (I)	0.02 (I)	0.02) 161
2.1 ()>	0.96 ()>	0.66 (41	0.48 (It	1.12 (l/l
0.02 (4)	0.04 (II	0.01 (2)	0.01 <2>	0.02/ (101
0.B9 (41	O.M (II	0.2) (21	0.16 (2)	0.)) (101
' Itlutl I* pai wtfm Iftdlcata lot aay aaasurad eonoaatratlont war* and to ¦
' Station location* fllvan la fIfurn 1-18.
concentration* glvan.
(PA Drinking Uatar Standard (Primary Swbttancal-I.4-2.4 ag/l (lanparatura Oapandantt
IH MPMI-CUK-I

-------
0468 »-7
IA8U 1-24
rtAw.r aesnwo kw oomxhimtions or totm. iron (in iig/n aj nc usrto siaiions1
SWtlcff1
1984
1969
1970
19 71
1972
1911
1914
I9»
1976
1919
1980 1902
1964
total
AverA^a
1)1104 VCt* a« Brldg*
¦bo ¦ tig Crnah
19)108 VCOR at tuiUr
ftrldp*, Ka|l«a
CIA
210.0 (I)
214.0 14)
118.0 (41
19)600 SrcOl a4Jaoaat
to CIA
Usui van
191161 Sunkar Cra*
19)112 II Ivor King
vO
00
19)110 UCOR i^ntrMl ai
&*lt«nlll« flail
i))))] vcm
fin* Crw6
15)201 PIm Craak
i»)02) sra* at
tnavllla
• 9)019 COR at
EmoIII*
iijoi* en at
C«ttl4>
94.0 in
2960.0 (I)
iM.o o>
110.0 (1) 270.0 (4) I7V0 (l> 116.0(17)	124.0(121	107.0(6) 168.0 (61
1)811.0(a) 29040.0(20)1)2000.0(9) 921)1.0 <»
411.7(6)	914.4	192.0(6) 106.2 I))
4671.0(121	11)6.0(11)	7140.0(10) 9ID.0 (10)
410.0 	212.0 (96)
7I7BO.O (4)	>9827.0 (J>	60612.0 (91)
107.0 (I)	411.9 (21)
2169.0 (7)	1216.0 (4)	4)98.0 (94)
212.0 (4)	296.0 ( 2)	6021.0 (17)
0(1) 221.0 (4)	49.0 (It	1411.2 (44)
2184.0 (7)	1146.0 11)	2690.0 (8))
1910.0 (4)	940.0 ( 2 )	2126.0 (2))
21.0 (I)	1.0 (I)	66.6 (9)
1129.0 (7)	60).O (!>	2101.0 (62)
II.) ())	1.0 ( 7)	160.0 ( 48)
184.0 (1)	106.0 ( 2)	944.8 ()9)
' lilaM I* pwwtlMti Indicate hen imh BMiurvd concantratloni mot» iih4 to calculate th* mh conoanlratlont glvan.
® Utflot location! §1 van In figure 1-10.
tM Drinking *>t» Standard (Swondiry V/bit«K») 100 |ig/l
118-WI-ftl-CUW-l

-------
1ABU )-2)
VUH.T OBSCTftO WAN ONXNIRAI IONS Of 101M. UM) (I*	AI W LISHO SIAIIONS1
Slttti
Taar
1966	1969	1910
1911	1971
197]	1974
191}
1916
I9K
1980	1982
1984
Total
Avaraga
1)3104 STOW at Brldga
»>ai« tig Cmt
I))I08 WCDM <1 8uaAar
Brldga, Hallog
Mr CIA
111600 SfCW *4J scant
to CIA
IIIKl STOW
hriiv M
1)1169 Bunker Cm*
1)11)2 Sllvar ling
Crmmk
u>
I
UJII0 WCBR ifntrMH of
lo	SaaltarvlII* Flat*
1)111) VOW a6»a
tin* Crmmk
l)J101 Pin* Cmt
i)km> trooi •«	ioo.o at
tnailll*
i)»i9 an ••	20.0 id
Cm. 111*
1)101* COM *1	10.0 III
Cataldo
66.0 (I) 19.0 (II
99.0 (41
U.O (41
14.1 (» IS.4 (II	46.) (I))
106.0 ()> 61.) (61 )).0 (II I0J.0 (111 80.1 (III	4J. I (61	12.) (61 >1.9 (6)	14.1 (61	IB.4	(»	61.) (691
4H.0 6.0 (Jl	10.0 (It	0).9 (18)
141.1) (lit 99.) (Ill	S1.0 (10)	I).6 (10) ».l (II) 19.1 (1)	11.4	<4)	61.1 (69)
KOO.O (I) 9000.0 (I) I99.Q (t) 1660.0 ()) JJ6.) (10)	911.9 (61	MO.O (4)	>41.0 (4) 0).) (4)	18.0 (41	10.4	(1)	681.4 (4»
10000.0 (It MOO.0(1) 9)2).) (6) >>06.0 (B) 829.9 (lOt	1410.91 (44) 1416.19 (81	10009.0 (I)	W.6 ())	19.0 (1)	1094.0 (91)
J9.0 (I) I MO.O (I) 1J9.0 (lit 411.1 (!)) I».) (4)) ))).0 <111 101.1 (6) M.) (6) 91.) (1) M.B (» IS.6
J0J.9 (111)
811.9 (4)
1)1.0 not
10.0 (6) >9.1 (9) 40.9 (4) 11.19 (1) 191.8 (Jl)
91.9(1)	19.0(1)	10.0(11	K.O (I) 11.0(1)	44.0(1)	).0 (I)	0.90(1)	l).)(ll)
906.0 (81 191.0 (8) 801.4 (111 M6.0 ())	112.9 (1)	I1J.) (61	196.1 (6)	11.2 (9»	J8.8 (9)	>1.0 (1)	2>.4 <)>	116.9 (18)
19.4 (9) 42.) (6) 18.1 (II) 10.0 (4)	10.0 (21	10.0 (1)	19.0 (4) 4.19 (4)	).0 (I)	18.0 ())	0.90 (1)	18.8 (49)
98.19 (4) 140.0 ()) 9).0 (81 81.1 (1)	40.0 ())	)9.0 II)	19.0 (4) 9.0 (4)	10.0 (I)	14.9 (1)	1.6 (1)	61.0 (41)
' Value* In pmtlhatai Indicate In mamf MaiarW ovcantrafIoaia war* uiad to calculafa lha —in cauanlritlaii glvan.
' Station locations glial In flgur« Kll,
CPA Drinking Watar Standard (Prlaury V*«tanoa) )0 ^g/l
EPA Haia>dwii Malta Standard (CP tonicity) MOO v9/l
IM-WI-M-CIAM-I

-------
IA8U }-M
TtMt.r CBSfRlrtO KAN CONCCNTOATJONS or roiM. HANGAtCSC (l« HB/U Al nc USftO srAriOHS1
Sudan*
•9/2
19/1
Tir
19/4
19 n
1916	19/9
l«eo	1962
1984
rali04
19)106
DMOO
yCW t« Br)dga
itom Big CrMk
tfOM .t fcnlwr
Brld^a, Kallof
> Nmt CI*
srim nijtcmti
to CIA
issm warn «bov«
Iwtw CrM*
19916)
19)1)2
ftafer CrM*
Sll>*r King
Cmt
imiio nam uptirM* of
SMltarvl 11« fl«1l
hum
19)20/
19)02)
19)019
srem
fin* Cri#
f Im CrMk
srem •«
luilllt
ON «t
Cu»lll>
• 9)011 CM «t
C4ttl*
1440.0(11
9.0(1)
910.0(1)
iso.om
92.01II 199.6(91 loe.O(l)
111.0(4)
/6.0O) 66.9(21
98.6(101
>40.0111
10200.0(0	4400.0(11
26)4.0(9) 1920.0(1)
4000.0(1)
9.0(21
690.0(1) 4142.0(2) 1200.0(1)
11)9.0(4)
220.0(91 400.0(11
•62.0(61	142.0(6) 192.0(6)	1)0.0(6)	121.0(6)	167.0(1)	160.0(40)
)/420.0())	609)).0(9) 29840.0(7)	2/90.0(1)	19399.0(4)	1)210.01))	>946).0(27)
194.0(9)	1/60.0(61 21).0(1)	29/.0O)	164.0(1)	290.0(10)
21)0.0(4)	9260.0(10) 2200.0(10)	2294.0(11) 1066.0(7)	604.0(9)	2966.0(46)
2062.0(4)	1/000.0(4) 1)90.0(4)	10)6.0(4)	611.0(4 )	9169.0(2)	4692.0(2))
12490.0(40)	9)79.0(6)	t)OO.O(l)	1942.0(41	19)4.0(2)	10692.0(9/1
2699.0(6)	9/96.0(6) 2400.0(6)	1609.0(2)	12/9.0(7)	110/.0(1)	2604.0(41)
2)1).0(61	1/29.0(9)	1)44.0(4)	1491.0(2/	I99).0(I6>
9.0(1)	6.0(1) 9.9(2)	20.0(1)	1.0(1)	4.0(1)	7.9(9)
2)00.0(6)	9900.0(6) 1910.0(9)	1910.019)	1102.0(/)	1162.0(1)	2606.0(42)
12.0(21	1.29(4) 1.0(4)	20.0(1)	2.00)	16.0(2)	222.0(211
210.0(2)	1120.0(4 ) 61).0(4)	900.0(1)	120.0(1)	>06.012)	70/.9(2))
' f«l«M In ptrantlWHi Mlult Im Mny muind eoncantrktloni a«r« uwd to ctluUh tha hmo conoantrttlcni Qlvan.
' tt«tlan IwalloM |I«h la flgur» 1-16.
[PA Drinking Hit«r Stwdird IStoondiry Subitum) 90 wg/(
I96-VPI-RI-CUIW-I

-------
IABU 1-2/
YUM.V OBSCRVCD WAN COMXNIRAIIOK Of TOIU tCfCURV (In !»#/¦! Al nc LISltD SIAIIONS1
Station'
1966
1969
19/0	1*11
19/2
197}
T«»r
19/4
19/)
19/6
19/9
I960 1982
1964
total
Av»r*ga
I»I04 VOIR «t Brldpt
¦ten Big CtmI
O.JO (I) 2.9 (I)
o.ea (4)
0.22 (4)
0.10 <» 0.05 (2> 0.49 (|)l
mioa uam at
Brldga, toI log
laar CIA
1)1600 STCOR adjacaat
to CIA
i»M2 sran ,
Bunk or Craak
1)116) BunAar Craak
I)11)2	SIImt King
CraaA
If 1110 SJCOM uptlraa of
Saaltarvllta flat*
IS1S1J srcm atxwa
rina Craak
II)20/	Plaa Om*
ISM21 tfCW at
(aaollla
1)1019 OR at
(twlllt
DMII cm at
Catalds
0.10 (2) 4.28 ( 41 ).00 ( 2) 0.66 (171
0.12 (61 0.20 (6) 0.0/ ()l 0.0/ (61 0.0) (II 0.82 Oil
0.9) (8) 0.12 (I) 0.20 (91 0.40 (/I 0.0/ (It 0.0/ (4) 0.0) (II 0.19 ()]>
0.20 (6)	0.12 (61 0.29 (II 0.12 (It 0.0/ (I)	0.1/ (19)
0.61 (121
J.O (I) 1.2 (I) 1.68 (I) 1.6/ (10)
163.0 (II 9.0 (I) 0.) (II 10.10 (8) 5.61 (101
1.0 (II 1./ (61 4.» (SI 0./6 (411
I./ (II
0.8) (101
I.I) (21	0.2) (21
1.2) (1) 1.44 (71 ).l! (Ill	1.19 (31	0.3/ 171
1.11 (II 0.33 (61 1.86 (III	1.4 (41	0.3 (21
1.17 (11 1.71 (II 2.37 (71	2.JO (71	0.17 ())
0.11 (101	O.M (101	0.08 (81	0.0/ (/I	0.0) (4>	0.26 Oil
0.98 (41	J.)4 (41	l.)2 (41	0.0/ (41	0.0) (21	I./I (Kl
11.8 (81	54.6 (II	0.0/ ())	0.0) (21	I/.I (1/1
1.44 (61	0.8/ (6)	0.20 ()l	0.16 (/I	0.0) (II	1.16 (841
1.11 (61	0.11 ()l	0.0/ (41	0.0) (21	0.67 (281
0.12 (II	0.60 (21	0.07 (II	0.0) (II	0.47 (91
0.87	I.II ()l	O.M ()l	0.11 (71	0.0) (II	1.86 (611
0.09 (41	O.M (41	0.07 (II	0.07 (II	0.0) (71	1.04 (401
0.06 (41	0.60 (41	0.07 (II	0.07 (II	0.0) (21	1.41 (1/1
' faluat la paraatfcatat Indicate In sany Htlmd ooncaatratlani Mora HMd to caleulata (la aaan oonoantrat lani gW
' Station location* glvaa la flgura 1-18.
IPA Drinking Natar Standard (Prlaary Subitanca) 0.2 110/1
IPA lUiafdMi Malta Standard (CP Tmlcltyl 200 119/I
D8-WPI-RI-CU.V-I

-------
IA8U 1-28
YI/M.V OBSTHIrtO KAN CONCCNtRATIONS Of TOTAL SritNIUH (In Pfl/I> AI nc 1 istto stations'
Station'
1966
1969	ISA)
f»>r
iv/j	iyi«
Total
191104 STCOR «t Brld^i
•bo** Bl| Croak
191108 STCW it Bunfcar
Or Idpa, tollof
SMpagii Mmt CIA
I)MOO SfCOD m«Mt
to CIA
s.;  i.o in
1.0 (4)
1.0 <11 1.0 (91
I.12 (6)
1.0 (I0>
191162 WCUt afaovo
1.0 (61
1.0 (61
ItJIU Burtar Cndt
191192 SI Ivor King
Crack
,|j (31110 UCW ifxtraa of
o	Snaltervlllo flati
NJ
DISH srcoft
rino Croak
9.0 (SI 2.0 (II
1.0 (21
1.0 (41
1.0 (41
1.0 (21
1.0	(41
4.1	(8)
191201 rina
ISI021 SrCOft at
faavlllo
1)1019 CUt at
foavllte
e.6 (III 2.0 (II
9.0 (B)
1.0 (II
1.0 (41
1.0 (2)
1.0	(41
6.1	(161
4.2	(101
191010 am at
Cataldo
4.) (II 2.0 (I)
l.» (41
1 lilun la parantfeotoi Indicate how May ¦oaturod concentration! tare utod to calculate tha MM concentration* gl«an.
' Station location* flvaa I* rigur* 9-10.
IM-UPI-RI-CUlV-l

-------
IA8U I »
VEAflLY OeStRtlD WAN CONIXNIRAIIONS Of IOTAL KMC Ha t>0/<> Al DC llSltO SIAIICNs'
Station*
IW
1969
1910
19/1
nn
19/1
ITaar
19/4
i*n
19/6
itn
1980 1961
1964
latal
><«<(•
1)110* tfCOl at Brlitg*
•bows Big CraaA
1)1106 srcn H Ouakar
Brings, bllo|
Mr CI*
l))U0 van *4J*oaat
ts CIA
niw srew >b»«
Ww M
I))I69 Ouotar Craah
1)11)1 Sllw ling
2X0.0(1) 980.0(11
966.0(4)
nn.om
1991.0(1) 140).0(7) 161/.0(D)
11)110 srcn I^ttrwa of
Siaaltarvllla fl*H
iMin sfcn
Pin* CraaA
1)120/ P Iim Cr
iijoi) srcn •«
(m*III«
191019 COM it
(••villa
own cm it
bill*
1700.0(1) 2190.0(8} 1119.0(1) l/f«./(l/t 29/0.0(11) I9/>.0(6I KW.OIfrl	1606.0(61 1070.01)1	21*0.00)	27)).Ot69>
ii)M.0(ai MJio.o(ii)iinw>.o(»ii»n).o(M	io/o.oiodi/o.om)	iai4o.o(4)	s«w.o<)4i
11)0.0(6) 1064.0(9) 4)00.0(6) 1600.0(1)	1600.0(1) 1)91.0(1)	10)1.0(16)
9106.0(11) 4991.0(111 11760.0(10)991).0(10) )l«).0(ll) >286.0(7)	1120.0(4) )9)4.0(6)>
1)100.0(1) 76500.0(1) 96)0.0(2) 169/0.00) 6410.0(10) 10600.0(6) 11)00.0(4) 69).0(4>	III7.)(4> 199.0(41	1440.0(1) 9)20.0(41)
169000.0(11 47)00.0(1) 91796.0(6) 167)6.0(8) 4/400.0(10) 109414.0(44) 4)WO.0(61 7)400.0(1) 6069.0(9)	9))0.0(1)	7)767.0(86)
21)0.0(11 16900.0(11 17991.7.0(12) 616l.7(/)> 4741.9(4}) 6/49.0(11) 1)9)1.0(6) 9011.0(6)	44I9.0(/) 110/.0(/)	1001.1(1)	6146.0(1/1)
147)0.0(4)
9/60.0(10)
9600.0(6) 4/00.0(9) 1/76.0(4) 11/0.0(1) 6)11.0(71)
160.0(1)	140.0(1)	169.0(1)	110.0(1) 169.0(1)	60.0(11	110.0(1)	104.0(1)	I19.0(IO
6600.0(7) M61.)(6I 1)164.0(16)	4910.0(1)	Mfl.OU)	6116.1(6)	11600.0(6) 91980.0(9)	1610.0(9)	2/67.7(7)	1961.1(1)	Z)19.0(/6>
24.6(4) 91.9(6) 67.9(11)	47.6(4)	61.0(1)	70.0(1)	11.0(4) 10.0(4)	20.0(1)	1.0(1)	0.90(1)	46.1(441
IIM.7411 1106.7(11 1/94.6(6)	1411.4(71	764.6(1)	24)0.0(1)	1190.0(4) 1690.0(4)	1210.0(1)	1109.1(1)	626.9(1)	1911.0(411
' faluat In piraatlwtM Indlcata how May ¦aimail coaeantratloni war* uwd to calculala II* ma concwitratlani glvan.
' Station locations jl*an In IIgurm 1-18.
(PA drinking Malar Standard (Saoondary StAttanoa) MOO |ig/l
ds-wpi-rt-cvih-i

-------
TABLE J-JO
rtwar obscrico km cqtcihtraiicms or total pti at ix listid stai iohx1
itiiii
I91D
1911
19/2
19/S
Yaar
1914
1979
*9/6
19/9
I960	1982
1984
Total
13)104 ST COM at Brldg*
(ton Big Ctm*
13)106 srcm at Bunkar
BrI dps. (allot
Naar CI*
I)>600 vcn <4|ml
to CIA
DIM} STCOR itan
Bunfc*r Cmk
193169 M«r CrMk
I9JI92 II Ivor tlmf
Crmmk
OJ
I
ro I3IH0 SfCOR upitrM* o*
O
t-
>it*r»nu run
ijdjj sraM «bov»
rin* Creak
193207 PlM Ctm*
193023 if a* *t
(•Mill*
13)019 CO) •«
r«w*iu»
i9»ia am *t
Cataldo
i.i fit
6.9 <11 1.0 lit
4.9 (II 7.9 (l>
i.l CI) I.I (l>
6.9 (II
r.l <21 6.7 (61	7.0 (61
6.S (It 5.8 (161	9.7 <61 I.) (6)
6.9 (It	6.9 (61
6.6 171	6.6 (lOt
6.1 (1) 6.) (41	6.4 (4t
4.9 (21 ).9 (6)	3.6 (St
9.3 (It 6.9 (II 6.) (60) 6.9 ()t 6.4 I7t 6.) (6)
1.0 (I)
6.) (21
I.l (It	7.1 (It
4.0(1) 6.0 (It 6.9(11) 6.1(9) 7.0(11	6.7	()t	6.6(4)
6.1 (I) 7.1 (ID (.1 (II) 6.6 (9) 7.6 III	7.1	(2)	6.6 (3)
6.6 (12) 6.6 (III 6.2 (I) 7.0 (It	6.9	()>	6.7 (61
6.9 (I)
6.9 (6) 6.7 (10)
6.9 (4) 6.7	(4»
6.6	(41
7.6 (I) 7.7 (J)
7.6 tit 7.9 (•>
7.6 (21
7.3 (21 7.1 (I)
7.) (It 6.9 (It
7.4 (I) 7.4 II)
I.l (8)
7.0 (20)
6.0 {}>	9.7 (32)
6.9 (6t
6.7 (191
6.0 (3)	6.6 (19)
7.2 (31 6.9 (I)	4.9 (22)
6.3 (611
7.0 (71
7.6	(It 7.4 (It	7.4 (91
7.2 (4) 7.0 (I) 6.6 (47)
7.7	(I) 7.6 (I)	6.9 14})
6.7 (47)
' hliM In pwn
-------
TABU J-JI
t[WT OBSIRHO mm OOKXNIRAIKM or rOfN. HU9VCSS ttaCO, In mg/n AT TIC 1ISI10 SIAIIONs'
lottl
Station'	1966	1969	WHO	I9M	I9II	197)	197*	1975	I9J6	1919	1980	1901	1904	A«ara
111104 SrCOR at tri6gm
> Blf I
M.O (I)
69.0 (I) 69.1 (41
74.0 (II
(69-«4|
1)1109 STCOR *4 Bunfcar
Brldga, Ullog
66.S (61
79.0 II)
66.) 14) 6).) I))
• M (14)
(64-79)
CI*
710.0 (J) III 1.0 (6)
79V0 (4) 710.0 Ml
887.0 (16)
(440-1570)
14)600 STCOR adjaoaat
to CI*
71.2 C»
64.0 (II
70.0 (16)
(64-80)
1)1)6} STam afeona
Bwitar Ctm4
110.0 (4)
IM.0 (I)
95.7 (7) 69.7 (4)
94.8 (16)
(12.5-IM)
15)16) Buafcar Craafe
1185.0 (4)
1100.0 II)
857.0 ( 4) 849.0 (I)
996.7 III)
(844-12)6)
CJ ISSOf Sll.ar tint
'	Craat
K>
0
01	15)110 STCOR Ufntrwi ol
Saaltarvllla Tl«ti
*1.« (5)
299.8 (6)
208.4 (8)
270.0 (II
M.O (4) 80.2 (I)
188.2 (6) 190.1 (I)
190.1 (II)
IM-IDI
168.4 (21)
<79-7/0)
I5)»l STCOR abova
flna Crmtk
260.0 (II
150.0 (4) 181.5 (I)
174.5 (7)
(115-260)
15)10) n«
17.0 (I)
15.0 (I) 18.8 (I)
16.9 (»
(15-18.81
15101) tfCOR at
(anil I*
20S.0 CI) 17.1 (16) M.O (6)
185.5 (6)
124.8 (4) 148.5 (2)
108.9 (SSI
126-205)
15)019 CON at
(aaOlla
25.6 (10) 10.5 (16) 17.2 (6)
22.5 (2)
D.O (21 22.8 (1)
21.) 
-------

TABIC )-)!
rttjar aesHiro ican aMcumAiioNS or iofm. sutrAits (in «g/ii m nc lisho siaiions'
___________	t >»» 1900 198?	1984 A.araga
111104 SfCOtt at arld0B	>'.0 (II II.) ()) 40.0 (II 29.0 (II	21.) (II 22.2 (7)
•ton* Big Craak
mica van •• mw	»i.o (it u.i (6> n.i oi> n.i <6i 49.0 (i> ».e (4i jo.o i«i	u.6 in u.z on
Br I dgm, Kaileg
CI*	;00.0 |l> 1074.0 (I0> IIJO.O (9) 76.0 (I) 906.0 (4)	740.0 (J) 1011.0 (Ml
ttttOO VCD* kUKMt	«'•« (91 11.0 (61 JI.O ()> M.O (I)	46.1 (191
to CIA
DIMl VCOR M		40.0 (II 88.6 (It) 119.0 (10) 1)4.0 (I) 104.0 (9> 61.0 (71	64.6 (4) 91.6 (4J>
19)165 tuikv Cn*	l>1.0 (It	IMI.O (6) 1092.0 (61 1169.0 1120.0 (II 1)30.0 (4) 8)6.0 (4 ) 740.0 (1) 1118.0 (28)
I5JIM Sll**r Klftfl	»I.O <¦>	° in.O CIO) 181.0 (B)	160.0 (it 51.8 (4> F9.8  m.O (SI)
Cra*
oj
^ 11)110 Sfa» unlrwial	161.0 (11 61.) (61	170.0 (12) 204.0 (6) 182.0 (1) »0.0(6) 161.0(6) 16).0 (J) 179.0(41)
O	Snlt«r>lll« riclt
cr-
I))»)	sra* •*»»•	40.0 (I) 88.6 (111 119.0 110) IM.O (I) 104.0 (9) 61.0 (7) 61.0 (41 92.8 (4))
Pins CtmA
II)207	rIns era*	8.0(11	4.1(2) 9.0(1) 9.0(1)	10.0(11 7.1(11 7.0(1)	7.4(81
UK 1) SfCW at	264.0 (11 991.0 (10) 11.0(1) 144.0(11	».)(6) IM.O (6> 177.0(6) 214.0(1) 2)8.0(4) 101.0 (4) 124.0 (2) 129.0 (44)
Ihi 111*
11)019 an *t	io.o (10) 10.0 (io> 10.0 (» i.o (i)	2.0 (2) 4.0 («i 2.8 (11 4.6  2.9 «> 2.4 ti> 7.6 iui
(navllla
11)018 cn at	19.9 (III >1.7 (10) 11.0 ()) 48.0 (II	92.0 (2) M.O (4) 81.0 II) 7V0 (I) 4).0 (2) M.6 (2) 40.1 ()7>
Ctlildb
' ftlutl la p*rmn1 Iwm ladlcato feOM Mny aaMurad eoncanfrat lent oar* us*d to calculate tha mmmn concent ratloni given.
' Station locations glran I* figura 1-I8.
(PA If/Inking Wjtaf Standard (Secondary Subftnc*) 500 |ig/l
IM-tri-RI-CUlV-l

-------
G499s-
-------
0439s -1
TABLE 3-33
ESTIHATCO AVERAGE LOADINGS AND PERCENT OF TOTAL BASIN LOAOING
IN IHL SOuTH FORK CCEUR D'ALEHE K'VER BASIN UNOE"
LOW FLOW CONDITIONS
Total Zinc
Survey Dale River Flow All Sources Leakage/Seepage Bunker Creek & Silver King Creek	All Other	T01AI
Hear Kellogg Above Bunker From CIA Area CIA Discharge Oischarge Nile Seepage & Inflows BASIN
(cfi)	(Hile 6.9) (Froro Hile fc.9 (HI 1e 5.3)	(5.0)	From Mile LOAD 1r


(above CIA)
to 5.3)





5.3 lo 2
.3



LBS/OAr
%
L8S/0AY
%
LBS/OAr
%
LBS/OA*
%
LBS/OAY
%
LBS/0/*
Oct. 9. 1974
79
1200
24%
1450
29%
160
3%
1900
38%
300
6%
500(
Oct. 7-9. 1975
122
1620
28%
1950
34%
400
7%
1330
23%
450
8%
5 7 St
Oct. 5, 1976*
79
1300
14%
3950
42%
1200
13%
1850
20%
1000
11%
9300
Sept. >8-19, 1979
66
760
30%
1000
40%
40
2%
10
—
700
28%
2500
Oct. 7-8. 1980
76
1070
42%
1070
42%
70
3%
10
—
330
13%
2550
Sept. 21-22. 1982
B9
1000
48%
650
31%
40
2%
40
2%
350
17%
2100
Sept. 26. 1984
95
1100
55%
550
27%
100
5%
20
1%
250
12%
2000
Note: *8roken waste line From zinc plant to CIA complex caused abnormally high loadings during this survey.
Source: Peterson (19B5, 10748).
I58-WPl-Rl-CULW-I

-------
10ASIM OF TOTAL 2MC Ml TMC SOUTH FOAJl COCUfl C'UIW ftlVCR 8ASM IMttCB
LW FLOW CONDITIONS
<000
3000
2000
1000
S 1964
ABOVtBn «
2 SIVBUMCROIUSO)
¦	AU.0T>«J
-------
04 99 *. -24
Tabl<» 3-34 and Figure 3-20 present a similar loading analysis for
fluoride loading. Fluoride is a conservative tracer (highly soluble and
non-ibsorbent) and provides an excellent means of determining
contamination of groundwater and seepage. The fluoride loading occurring
in tne SFCDR drainage has been reduced from an estimated 1250 lbs/day in
1975 to 370 lbs/day in 1984. However, the estimated percent contribution
of the Bunker Hill complex area has remained about the same (70-90
percent). Total percentage loading to the SFC0R of fluoride for the
entire project area has also remained in a range of 95 to 99 percent.
The main source of fluoride loading to the SFCDR is from the CIA.
A September 1982 study by Peterson and Findley (1982, 10001) estimated
the percentage increase in various pollutant constituents as the SFCDR
flows past the Bunker Hill property. Table 3-35 presents Peterson's
finc.ings, along with additions from the 1984 survey. Significant
increases in many constituents including the metals cadmium, zinc,
manganese, and copper were observed. Lead levels increased only slightly
in 1:he SFCDR. Lead levels, however, are generally low in the SFCDR
waters due to improving pH conditions in the stream. This does not
preclude the transport of lead by the SFCDR as sediment. Other water
quality parameters which had significant increases were phosphorus,
calcium, and sulfate. The only major changes in absolute loading from
1982 to 1984 appeared in iron, phosphorus and sulfate, which were cut
about in half.
Also found in the Peterson and Findley (1982, 10001) study were
significant concentrations of PC8 1260 in Bunker Creek of 0.56 yg/l
and Silver King Creek of 1.060 ng/t. It is known that there are many
transformers containing PCBs on the site. No other water quality data on
PCB contamination were found during the review of available literature.
This is a significant data gap.
Harmon and Johann (1980, 30054) found cadmium levels 1n the SFCDR in
Detember, 1975 at Smeltervllle of 116 yg/l and estimated a load of
3-210
158-WP1-RT-CULW-1

-------
0439S-2
TABLE 3-34
ESTIHATC0 AVERAGE LOAOINGS IN THE SOUTH FORK COEUR O'AIENE RIVER BASIN
LOW FLOW CONDI I IONS
Total Fluoride
Survey Oate River Flow Alt Sources	Leakage/Seepage
Near Kellogg Above Bunker	From CIA Area
(cfs) (Nile 6.9)	(From Nile 6.9
(above CIA)	to S.3)
Bunker Creek &
CIA Discharge
(Nile 5.3)
Silver King Creek
Olscharge Mile
(5.0)
All Other	TOTAI
Seepage & Inflows	BASK
From Mile	LOAOlt
5.3 to 2.3


LBS/OAY
X
IBS/DAY
X
LBS/DAY
X
LBS/DAY
X
LBS/OAY
X
LBS/0/
Oct. 9. 1974*
79
—

—

—

—

--

--
Oct. 7-9, 1975
122
27
2t
975
78X
160
13X
35
3X
50
4X
1 251
Oct. 5. 1976
79
15
IX
965
78X
170
14X
30
2%
60
5X
124(
Sept. 18-19. 1979
66
10
IX
400
36X
690
63X
5
—
0
--
1 IOC
Oct. 7-8, 1980
76
17
3%
460
7IX
100
15X
Damned
—
70
11X
65(
Sept. 21-22, 1982
89
16
3%
350
56X
250
40X
5
—
0
—
6 2b
Sept. 26, 1984
95
19
5%
280
76X
21
6X
1
—
40
ux
37(
Note: 'Incomplete
Source: Peterson
Fluoride analysis taken In
(1985. 10748).
October
1974 study
•






I 58-WPI-RT-CULW-I

-------
LOAOIM or TOTAL HUCRJDt M TX SOUTH »0«* COEUR OALtMt RIVER BASIN UMtCH LOW FLOW
coMoirwNs
¦
1975
B
1976
~
1979
~
1980
Q
1982
~
1964
ABOWt S* (rtlE 6 9) UAKAKCiAtnH 6tWK£R CS (rili
6 9 - 3J)	5 3>
location w skw
S1VMKW6CR
(ruii 3 0)
gg n n.
«u on)
B LEMUa CIA nil 6 9 T05JJ
¦	BUKROKnUSJ)
~	SlLVOKM CSOIU S 01
¦	MLoncR
-------
imis-i
TABLE 3-35
BUNKER HILL FACILITY AREA IMPACT ON
SOUTH FORK COEUR O'ALENE RIVER
September 21 and 22, 1982
EPA Survey, Average Concentrations

SFCOR Above
Bunker Hill
SFCOR Below
Bunker Hill




Parameter
at Bunker Avenue Bridge
Near Airport
Percent
Increase
Lbs/day

(Station
15310B)
(Station
153110)
in Concentration
Increase
in Loading

1982
1984
1982
1984
I9B2
1984
1982
1984
Flow cfs
89
95.2
107
105.5
20
11


Calcium mg/1
13.4
—
34.6
—
160
--
13.600
¦-
Sulfate mg/1
30
38.6
160
1163
430
310
79.000
73,000
lotal Phosphorous mg/1
.010
.008
.385
.126
3750
1475
216
68
Fluoride mg/1
.04
.04
1.09
0.58
2600
1350
620
310
Arsenic ug/1
<2.5
8.1
<2.5
8.3
None
2.0
—
.6
Antimony ug/1
<2.5
18.10
<2.5
13.0
None
None
--

Cadmium ug/1
13.2
20.9
.21.4
28.6
60
40
5.9
5.5
Copper* ug/1
2.2
1.4
4.0
4.1
80
190
1 .3
1.6
Iron ug/1
55
21.7
2400
1146
4300
5200
1,350
640
lead ug/1
24
18.4
28
18.6
17
1.0
3.6
1 .1
Manganese ug/1
122
167
1270
940
675



Mercury ug/1
<0.7
—
<0.7
--
None
—
--
--
Zinc ug/1
2050
2140
3220
3003
60
40
870
610
Sources In this area Include: 1) Bunker Hill CIA pond leakage/contaminated groundwater.
2)	Bunker Creek (treatment plant discharge).
3)	Silver King Creek (drainage through area of zinc and fertilizer plants)
•September 21. 1982 results only.
'.mini- Peterson and Flndley (1982, 10001)

-------
0499s-25
300 lb/day, of which 270 lb/day came from the Bunker Hill area. The zinc
concentration at Smelterville in May, 1976 was 1400 jig/l and a
loading of 13,000 lb/day, of which about 8000 lb/day was attributable to
the Bunker Hill area. Lead levels in May 1976 at Smelterville on the
SFCDR were 30 yg/l, which is a loading of 276 lb/day. About 30
percent was attributable- to the Bunker Hill area.
Heavy metal levels in the SFCDR are and have been so high that no known
species of fish are resident in the SFCDR, near or below the project area
to the confluence of the SFCDR and CDR. The fisheries are also limited
in the main stem of the CDR below its confluence with the SFCDR during
summer and fall low flows (Wise 1981, 10003). However, a population of
kokanee has been found upstream of the project area (near Mullan) in the
past few years (from 1982 and on) and it is believed that the fish passed
through the project area from Lake Coeur d'Alene (Homer 1985). Live box
bioassys done in 1973, 1974, and 1975 in the SFCDR gave a time to 50
percent mortality at SFCDR at Enaville from 6 to 20 hours. At the Bunker
Hill site in 1979 time to 50 percent mortality was 10 hours. In the CDR
above Enaville, there was no mortality (Kreizenbeck 1979, 10253). In a
1982 live box bioassy, no mortality occurred in the CDR below the
confluence of the SFCDR and CDR (at Cataldo), suggesting that pollution
levels have been reduced to below acute levels (Peterson 1985, 10748).
3.3.3.3 Bunker Hill Complex Water Quality
A schematic view of water effluent flow on the Bunker Hill complex is
shown in Figure 3-21. This map was completed on January 24, 1977 and is
not a current description of water flows on site. The complex has been
shut down since 1981 and many of the discharges and water flows shown are
not active.
Currently, at the Bunker H111 complex there are only three active
discharges under NP0ES regulations. The first discharge is the central
treatment plant effluent (NPDES discharge number 006). This plant treats
3-214
158-WP1-RT-CULW-1

-------
049aS-jc
metal pollution. They found that data obtained from tree cores and
rings, by determining metal content as a function of tree ring age, was
in rough agreement with sediment data from Lake Coeur d'Alene. It also
matched data on volume of ore mined from the COR mining district. An
allowance for metal holdup in Lake Coeur d'Alene was made in the data
compari sons.
3.3.3.6 Sunwary
The documented loading surveys and most of the changes noticed in water
quality occurred during changes in operation of the Bunker Hill complex.
This indicates that the Bunker Hill facility was and is probably the most
significant single contributor of heavy metal pollution to the SFCDR.
3.3.4 GROUNDWATER CONTAMINATION
This section addresses the extent and degree of groundwater contamination
in the project area, and focuses on three probable major sources of
groundwater contaminants: the Central Impoundment Area (CIA), the
unconfined mine and mill wastes at Smelterville Flats, and the Page
wastewater ponds.
The CIA remains the likeliest source of contamination. The Williams et
al. (1979, 50231) study reported high concentrations of zinc, lead, and
cadmium, among others, in the combined inflows of mine and smelter
waters. The resulting pond water contained (and 1s likely to still
contain) high levels of these metals and low pH values (Table 3-35).
Since the pond dike materials have a very low but still measureable
degree of permeability, seepage from the pond probably has Infiltrated
the basal allovlum and contaminated the groundwater.
Table 3.38 lists zinc concentrations in water samples collected by the
Bunker Hill Company and Bunker Limited Partnership from selected
monitoring wells. Figure 3-26 charts these concentrations for the period
3-229
158-WP1-RT-CULW-

-------
Table 3-38: Zinc Concentrations Cmg/1) in Water
Samples from CiA Monitoring Wells
Well *9
Well *25
Date
Well *8
4/8!
13 30
1370
0 56
6/81
7 60
11 80
0 60
8/81
9 30
If 00
061
10/81
7 10
10 20
0 64
12/81

11.50
0 85
2/82
3.10
12.80
0 87
4/82
2.00
10 20
0.57
6/82
0 70
8 30
0.52
8/82

8.00
0 56
10/82

7 90
0.59
12/82
1 60
8 30
0 62
2/83
1.50
5 50
0 38
4/83
0.16
6.80
0 57
6/83
0 14
6.70
0 39
8/83
0 07
6.90
051
10/83
0.29
7.60
0.46
12/83
2.20
6.50
0 58
2/84
0.84
6.40
0.39
4/84
0 03
6.40
0 56
6/84
< 0.01
6.30
0.41
8/84
0.01
6.10
0.44
10/84
0.15
6.10
0.55
12/84
< 0.01
7.26
0.22
2/85
0.06
7.50
0.59
4/85
0.29
6.89
0.56
6/85
0.06
6 65
0.67
8/85
0 29
6.92
0.61
Figure 2-15 shows well locations.
Source: BLP File *WP-024
158-WP! -RT-CULW-1
3-230

-------
6 10 2 6 10 2 6 10 2 6 10 2 6
81	82	83	84	85
Date
¦ CM Well *9 S CIA Well *8 ~ CIA Well *25
Figure 3-26: Comparisons of Zinc Leuels in Clfl Wells
158-UJP1 -RT-CULUJ-1
3-231

-------
0499s-33
1980 through 1985 and reveals an apparent decline over time for the two
most contaminated wells. In both wells 8 and 9, winter and spring
concentrations greatly and consistently exceed those of summer and fall.
Well 8 exhibits a drastic drop in zinc levels that apparently corresponds
witr the shutdown of plant operations in 1981. Well 25 is upgradient
from the CIA and appears to show background levels of zinc in groundwater
entering the study area.
Many studies have covered the occurrence of seepage and metal transport
from the CIA (Norbeck 1974, 30057; Sceva and O'Neal 1975,?; Reece 1977,
10773; Rouse 1977, 10179; Williams and Ralston 1977; Hawke Engineers
797J3, 10181; Williams et al. 1979; and Robinson et al. 1980, 10181), but
non<» have specifically targeted the extent and degree of groundwater
contamination. Thus, the information available appears insufficient to
delineate the spread of contamination to groundwater from the CIA beyond
the perimeter well network established by Bunker H111, EPA, and various
consultants and other investigators. However, Sceva and O'Neal have
indicated that CIA seepage moves far enough north to enter the South
Fork. Also, high levels of heavy metals do appear in groundwater study
analyses for the Smelterville Flats, but lack of geochemical control
between the flats and the CIA prevents associating the levels with
tailings pond leakage.
In general, high concentrations of heavy metals in groundwater occur next
to the tailings pond and 1n the flats downstream from the CIA. In
industrial wells adjacent to the waste treatment plant on the southeast
boi-der of the CIA, Norbeck (1974, 30057) found zinc and cadmium in levels
as great as 50 mg/l Zn and 0.1 mg/l Cd. These values appear to have
re Fleeted partly diluted direct seepage from the CIA, since later studies
ha/e shown that groundwater beneath the CIA apparently flowed in all
directions (Section 2.9.4.2). The maximum levels Norbeck found 1n the
flats just west of the CIA were 19 mg/l Zn and 0.07 mg/t Cd.
3-232
158-WP1-R7-CULW-!

-------
The Hawke Engineers (1970, 30051) and Robinson et al. (1980, 10181)
studies report high levels of zinc in groundwater supposedly derived from
the lower gravel aquifer. Whether contaminants originating from the CIA
have indeed entered the confined lower aquifer remains unknown. Well
data show that, at the time of the study, the depth of the potentiometric
surface generally was above the clay aquiclude in wells finished in the
clay, (upper aquifer, or unconfined, wells) but that the water level
dropped to within the clay zone for wells finished in the lower gravel
(confined wells). The radical difference in water levels suggests little
or no hydraulic connection between the lower and upper aquifers and, by
extension, between the lower aquifer and the CIA. Analytical results
listed also show no relationship between concentration and depth—the
highest concentrations occur in one confined and two unconfined
piezometers. Rather, these levels are related to soil disturbance around
the area where the buried separation dike joins the northern wall.
Marcy (1979, 50228) analyzed groundwater taken from different depths in
the Smelterville Flats sediments and graphed the concentrations with time
and with depth. Marcy's data indicate that the greatest concentrations
occurred in the shallowest zone sampled and in the zone closest to the
river. Concentrations generally decrease with depth and perpendicular
distance from the river, although extreme anomalies occur locally.
Evidently, the primary source for the high levels of metals in the flats
area includes surflclal deposits of old jig tailings intermixed with
alluvium. The water table may have risen high enough to leach metals
from the soil. Although Marcy neglected to list piezometer elevations
for the corresponding measured elevations of the potentiometric surface,
his thesis noted white encrustations of calcic material on the flats,
suggesting a high water table. Since Norton (1980, 10766 and 10809)
noted a hydraulic connection between groundwater and ponded water on the
flats, the groundwater very likely contains high concentrations of heavy
metals.
3-233
158-WP1-RT-CULW-1

-------
3499 s-35
The total quantity of metals leached from the Smelterville Flats area and
transported by the upper aquifer is minute in comparison with the total
iJaily volume of metals released by the CIA through leakage from the
pond. Marcy calculated a daily discharge of 5.3 leg (11.7 lbs) of zinc to
groundwater from the flats. On the other hand, the CIA discharges a
:otal of 244 kg (538 lbs.) of zinc per day (see Section 2.1.4.2).
I:igure 3-27 indicates the probable extent of groundwater contamination
lielow the complex. The two greatest sources are the CIA and Smelterville
3
Rats. Assuming that groundwater discharges at 1800 m /day (0.67 cfs)
,it the downstream end of the study area (Section 2.1.4.1) and a total of
;!50 kg/day (550 lbs/day) of zinc enters the unconfined aquifer system,
!he average Zn concentration in groundwater downgradient of the complex
would be 18.6 mg/1. Alternatively, were the discharge about 6300
m3/day (2.42 cfs) across the valley at the CIA site (Section 2.1.4.1),
1.he Zn concentration would average 5.3 mg/1. These discharge rates are
c.pproximations based on estimates of saturated thickness, average aquifer
width, and groundwater velocity. The zinc concentrations generated also
do not necessarily reflect confined aquifer concentrations, groundwater
discharge to the SFCDR River, presence or dispersion of contaminant
filumes, adsorption of zinc onto particulates in the groundwater or in the
i.emi-confining silty clay layers described in relevant drlllers's logs,
or actual zinc input from source areas. Nevertheless, the high Zn levels
in both examples indicate a substantial contribution to the groundwater
from Bunker H111 sources.
little information 1s available on the current impact of water leakage
from the Page ponds. In 1975 Morilla estimated that 8.1 kg/day (17.8
lbs/day) of line leaked from the ponds and Infiltrated the alluvium to
croundwater. However, the Page ponds have since been converted to sewage
treatment, and no further studies reviewed have considered these
wastewater ponds as a source of heavy metal contamination to groundwater
in the South Fork basin.
3-234
158-WP1-RT-CUIW-1

-------
04 9 9 s - 51
3.3.7 OTHER BIOTIC COMPONENTS
Table 3-45 summarizes available information concerning heavy metal
concentrations found in various biotic components of the Coeur d'Alene
River Valley ecosystem. Values listed are in parts per million (ppm)
starting with organic detritus and continuing through to the mammals.
Often a blank space occurs under a metal for a particular biotic
component. This indicates that the metal concentration was not assessed
in that circumstance. If "ND" occurs in the space, this indicates that
the metal concentration was assessed, but the level was not detectable.
In overview, much of the data was collected in the early 1970's. Recent
data is limited to some fish and mammal work performed in 1982. A
comprehensive survey of present levels of contaminants in biotic
components may reveal lower, values as a reflection of improvements in
surface water quality. Of the reported metals, zinc, mercury, copper,
lead, and cadmium have received the most attention.
By far, the most complete record is for zinc. This element generally
occurs in the highest concentrations relative to the other metals.
Figure 3-28 summarizes zinc levels in various trophic levels of the Coeur
d'Alene River Valley ecosystem. Mean values (+ one standard error) were
derived by averaging the values reported within each biotic component
(e.g., all the aquatic insect data). The bird data do not contain the
1931 values for dead swans (Zn levels 14,000-27,000) as they are
extremely high and may not be representative of more recent conditions.
As can be seen 1n Figure 3-28 in 1973-74, organic detritus contains
especially high levels of zinc. The organic debris is the basis of the
detrital food chain, where numerous benthic organisms (e.g.,
oligochaetes, snails, and some aquatic insects) consume the dead,
decaying organic materials which accumulate in the aquatic ecosystem to
derive energy and nutrients. The high levels observed in the detritus
indicate that, if these levels are still accurate, organisms which rely
3-26?
158-WP1-RT-CULW-1

-------
TABLE 3-45
SUMMARY OF HEAVY METAL CONCENTRATIONS IN VARIOUS BIOTIC COMPONENTS
Metal Concentrations (ppmI
Blotlc Category	Taion
Habitat
Pb Cd	In Hg Cu Se	Sb	Year
Comments
Reference
Organic detritus
Coeur d'Alcne R.
Upper Spokane R.
SO.119
2658
19)3
1974
Funk et at. 19)5
Funk et al. IS J 5
Filamentous
Green Algae
Sttwclonlup sp. Upper Spokane R.
2630
19)4
funk et al. I9)S
Perlphyton	Cladophora sp. Upper Spokane R. 1)0 36 1900 I.I 32
1974 Atomic Absorption
Analysts (AAA)
funk et al. 19)5
Aquatic Plants Not Specified
i
K)
a>
tlodea »p.
(vase, aquatic
plant)
Ufi&i sp.
(vase, aquatic
plant)
*P-
(vase, aquatic
plant)
P°H*«9tt°n *P-
(vase, aquatic
plant)
Potaaegeton sp.
(vase, aquatic
plant)
Potameqeton sp.
(vase, aquatic
plant)
Potamegeton sp.
(vase, aquatic
plant)
Coeur d'Alene 1500-
Valley	3)00
1300-
2300
15-
150
Upper Spokane R. 1200 105 4200 0.8 01
Upper Spokane R.
1863 0.)5
Upper Spokane •. 320 20 1310 0.04 32
Upper Spokane R.
Upper Spokane R.
Upper Spokane R.
Upper Spokane R.
B6I 0.50
2298 2.04
4041 3.02
NO • Not Oelected
1962 Method not specified Chupp and Oalke 1964
19)4 AAA
Funk et al. 19)5
NO 1.06 19)4
Neutron Activation	funk et al. 19)5
Analysis (NAA). whole
body
19)4 AAA
NO 0.4) 19)4 NAA. leaves
246 NO NO	NO NO	19)4 NAA. stems
3.09 6.85 19)4 NAA. roots
Funk et al. 19)5
NO 0.51 19)4 NAA, whole plant	Funk et al. 19)5
Funk et al. 19)5
Funk et al. 19)5
Funk et al. 19)5
I5B-WPI-8J-BKC* I

-------
U4J.
SO
e
1370
0.3
14


1914
AAA
furl et al. 1975

Aablvsteqlua
jurat tkaniM
tipper Spokane 1.


2123-
2435
0.79-
0.98

1.02-
1.6
1.65-
1.73
1974
NAA, whole body
funk et al. 1975

«p-
(¦»»)
Upper Spokane >.


5304
1.22

1.78
5.35
1914
NAA, whole body
Funk et al. 1975

fflVlttlP" *P-
(horsetail
rush)
Upper Spokane R.


485
NO

HO
O.IS
1974
NAA, whole body
funk et al. 1975
Aquat Ic
Ollgochaetes
(woras)
Upper Spokane #.
16
4.3
450
0.3
17


19)4
AAA
funk et al. 1975

Phvsa sp. (Snails)
Upper Spokane R.
46
131
1500
0.5
250-
340


1974
AAA
funk et al. 1975

Phvsa sp. (Snails)
Upper Spokane R.


116.9
0.56

NO
0.54
1974
NAA, whole body
funk et al. 1975
Aquatic Insects
Baetls so. fftavfly) Upper Spokane A.
no
70
3120
0.7



19)4
AAA
funk et al 1975

Hvdropsvehe sc.
(caddlsfly)
Upper Spokane R.
33-
350
29-
4S
560-
3060
0 2-
l.l



1974
AAA
funk et al. 1975

Hvdropsvehe so.
(caddlsfly)
Upper Spokane fl.


396-
900
0.15-
1 OB

0.19-
1.43
0.76-
1 .47
1974
NAA, whole body
funk et a 1. 1975

PoWcentropus so.
(caddfsMy)
Upper Spokane R.


204-
925
0 47-
0.69

NO
0 22-
1.94
1974
NAA, whole body
funk et al. 1975

Glvptotendlpet sp.
(cMronoald)
Upper Spokane R.
68
16
1050
0.1



1974
AAA
Funk et al. 19 75

Ch 1 ronorildae
1 mldijf i)
Spokane River


869 6




1974
Method not specified
funk et al 1975
NO • Not Detected










1 SB MPI-Rr-BKCX-?

-------
TABIC 3-45
(continued)
SUMMARY OF HEAVY MEMl CONCENTRATIONS IN VARIOUS BIOTIC COMPONENTS
Metal Concentrations (ppal
Blotlc Category
lnon
Habitat
Pb
Cd
7n
Hg Cu
Se
Sb	Year
Comments
Reference
Aquatic Infects Chlronoaridae
(contInued)
Slaulldae
(files)
Cordulla sp.
(dragonfly)
Chaoborus sp.
Heleldae
ri»h
nebutomt
(brown
bullhead)
Ictalurus
nebulosus
(brown
bullhead)
Perca
(yellow
perch)
f'mWPI
(yellow
perch)
irofieli
plbbosus
(puapklnseed)
Lesonli
glbbosus
(punpkInieed)
Anderson L.
Spokane R.
Anderson L.
Anderson L.
Anderson I.
Coeur d'Alene R.
Valley lakes
Coeur d'Alene I.
Valley lakes
Coeur d'Alene I.
Valley lakes
Coeur d'Alene R.
Valley lakes
Coeur d'Alene R.
Valley lakes
Coeur d'Alene R.
Valley lakes
NO
50-
866
16IS
NO I8S
NO
NO
0.16-
0 17
1.3-
64
530
IBB
18-
26 2
122-
426
0.11- 22-
0.8S 92
1.6- 30-
36 513
0.15- 19-
3.B 126
2 3- 37-
33	219
13-
52
3?
66
0 3-
3 6
1973
Rabe and Bauer Mir
13-
100
0.2-
7.5
1.7-
110
0 3-
9 B
3.8-
15
I9M Method not specified Funk et al. 1975
1913	AAA
1973	AAA
1973	AAA
1973	Muscle tissue, AAA
Rabe and	Bauer 19 7 7
Rabe and Bauer 19 7 7
Rabe and Bauer 19 7 7
Rabe and	Bauer 197 7
1973 liver tissue. AAA	Rabe and Bauer 1977
1973 Muscle tissue. AAA	Rabe and Bauer 1977
1973 liver tissue. AAA	Rabe and Bauer 1977
1973 Muscle tissue, AAA	Rabe and Bauer 1971
1973 liver tissue. AAA	Rabe and Bauer 1977
NO • Not Detected
I58-WPI-RT-BKCX-?

-------
TABIC 3-45
(centInued)
SUMMARY OF HfAVt NCtAL CONCtNIRATICNS IN VARIOUS BlOflC COMPONENTS
Metal Concentrations fppm)
Blotlc Category
Ti««n
Habitat
Pb Cd
In N] Cu Se	Sb	Year
Comments
Reference
Flilt
(continued)
Pcaoilt
(black crapple)
Pomo»ls
ol9rw
-------
TABLE 3-45
(concluded)
SUMMARY OF HCAVY MtlAl CONCENTRATIONS IN VARIOUS BIOTIC COMPONENTS
Metal Concentrations (opal
Blotlc Category
Taion
Habitat
Pt Cd
X
e
fs*
Cu Se
Sb
Year
Conmenls
Reference


Olor
coluoblanut
(whistling
swan)
Coeur d* Alene
River Valley
40-
50
4-
s
S-
5.6

1955
•Sick* swans,
t ibla-fIbula
Chupp and Oalke
1964
Birds (continued)
Olor
coluablanus
(whistling
swan)
Coeur d' Alene
River Valley
)0-
190
14000-
21000
120-
190

1931
Oead swans.
Internal organs
Chupp and Oalke
1964

Meraus
¦*r9««»"r
(coanon
Merganser)
Coeur d,' Alene
River Valley
NO
NO
S.O

1955
Healthy; liver
Chupp and Oalke
1964










i
•j
'
Anus
aaerlcana
(American
Wlgton)
Coeur d1 Alene
River Valley
NO
10-
16
19-
33

1955
Healthy; liver
Chupp and Oalke
1964

Anuf
(Mallard)
Coeur d' Alene
River Valley
12.0
3.5
35.0

19SS
Healthy; liver
Chupp and Oalke
1964
Nwult
Mice (species
unknown)
Coeur d' Alene
River Valley
up to
180



I9B2
Whole bodies
Woiritn 1985


Mustela
rli5il
(¦Ink)
Coeur d' Alene
River Valley
21



I9B?
liver
Wolf 1tn I9B5

NO - Not detected
I5B-WPI-Rr-BHCK-?

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0499s-52
on these materials for a major portion of their sustenance will be
exposed to high levels of zinc.
Plant species also appear to accumulate relatively high levels of zinc.
Uptake may be from the sediments or by direct adsorption from the water.
The snails and aquatic insects also contain relatively high levels of
zinc; however, the fish and birds apparently do not. Moreover, most of
the zinc in fish appears to concentrate in the liver and not the edible
muscle tissues (Table 3-45). While the bird values are generally low, it
should be remembered that waterfowl mortality has been observed on
numerous occasions in the Coeur d'Alene valley, and heavy metal toxicity
has been implicated in the birds' deaths (Chupp and Dalke 1964). The
most recent incident occurred in the early 1980's (Idaho Department of
Fish and Game, personal communication, September 1985).
The levels of metals found in some of the biotic components of the Coeur
d'Alene River Valley ecosystem have been compared with levels in
components collected from undisturbed ecosystems. Rabe and Bauer (1977)
observed that the mean concentrations of zinc in liver tissues of yellow
perch collected from Coeur d'Alene Valley lakes were significantly higher
(0.05 level) than concentrations from control fish. Levels of copper and
cadmium were not significantly different. Furthermore, in a comparison
with values reported for other studies, they concluded that the
concentrations found in the Coeur d'Alene Valley drainage fish were
similar to the values reported for other studies (Rabe and Bauer 1977).
3-269
158-WP1-RT-CULW-1

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Bunker Hill Mining & Metallurgical Complex
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Bunker Hill Superfund Site Fact Sheet;
EPA Region X; February 26, 1990

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TZ4 - C10 Cl—	^2^
JSfFRflL Region 10
^¦1 **	Superfund
February 26, 1990
Bunker Hill Superfund Site Fact Sheet
Kellogg, Idaho
On January X, 1990. the Inspector General Issued a review of the Bunker HIB Superfund Protect
The following Is a brief update on topics touched on In that review. The Inapector General's office Is
an Independent am of the Environmental Protection Agency aet up to prevent and Investigate wasta,
fm*i,andr"
Site Background
"7>e Bunker Hill site is one of the largest and most complex Superfund sites in the nation. The sue is a 21
square mile area located in the Silver Valley of northern Idaho. Problems ndude:
•	Elevated levels of lead, cadmium and various other metals throughout the site, including residential soils
•	Asbestos on deteriorating buildings at the smelter complex
. PCB contamination at the smeftef complex
•	Waste piles, drums, and tanks
•	Windblown dust carrying potentially hazardous levels of metals
"he EPA Superfund program has been involved at the site since 1963. The site has been a major concern
for EPA because testing continues to show high levels of lead in the blood of some cttidren living in the area.
The yearly blood Lead Screening Program oonducted this August (1989) identified eight children with
eleviited blood lead levels. Lead can cause nerve and Kidney damage.
Hecilth Advisory
An inspection of the smefter complex conducted by the Agency lor Toxic Substances and Disease Registry
resulted m a Public Health Advisory which was issued in October 1989. The advisory concluded the smelter
comalex was a significant nsk to public health.
Sm alter Complex Clean Up Actions
> n October of 1989. EPA ordered Gulf and Bunker Limited Partnership to remove and contain hazardous
subs tances, halt demolition and salvage operations.
As a result of EPA's order, several thousand feet of fence was installed around the smelter, a copper dross
Hue dust pile was covered, and a substantial amount of deteriorating asbestos was removed. In addition to the
immediate response actions, the parties were ordered to develop plans to address site security, asbestos and
PCEi removal, fire protection, dust oontral, ua safety, and decontammatcn of salvage material.
Poientlally Responsible Parties
Gulf Resources and Chemical Corporation, Bunker Limrted Partners h*j. Minerals Corporation of Idaho.
Bun
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Residential Soil Removal Program
In the summer of 1989, contaminated soil was removed from 81 residences and 2 large apartment
complexes. Yards chosen for the program had soil lead levels of 1000 ppm or greater and where children less
than 4 years old or expectant mothers resided.
The agency plans to continue the residential soil removal program in the summer of 1990. It is expected
that about the same number ot properties will be completed during the 1990 program.
In 1986. EPA removed contaminated sod from 16 partes, playgrounds, and road shoulders. EPA has
recovered $1.4 million from Gull Resources for costs incurred by EPA dunng the 1986 removal.
Disposition of Salvaged Railroad Ties
The Inspector General's report indicated that contaminated railroad ties left the site. EPA has asked both
the salvage company and BLP for their records/information regarding the whereabouts of the ties. EPA is
continuing to pursue this matter.
Ongoing and Future Actions
•	EPA will soon enter into negotiations with respoostole parties for the 1990 residential sotl removal program.
If those negotiations are not fruitful. EPA will issue an order to the respcnsble parties to perform the work.
If there is no response. EPA will perform the work and seek to reoover oosts.
•	EPA and Gulf Resources will soon begin negotiations on revegetatkxi of hillsides to prevent wind from
carrying contaminated soils off the site.
•	EPA will continue to demand that Gulf Resources finish one of the most extensive site investigations ever
conducted at a Superlund site.
For further information, please contact
Carolyn Young at (206) 442-1203.

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Bunker Hill Mining & Metallurgical Complex
Mining Waste NPL Site Summary Report
Reference 3
Excerpts From the Coeur d'Alene Mining
District in 1963, Pamphlet 133;
Idaho Bureau of Mines and Geology; 1963

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'V->	„„
T*r c."- 4,4'— *—' *
Zr.r. yjKKZR HILL CO.V.-A.V'/ OPERATIONS
- :-::s"Civ o"	hill company
; — - He:.'a.a, G?"3r=. y.a-cge-
T-c -^v?' H111 Ccr.ca-'y tocav :_j a major 'J. S. producer of lead, silve-
i-d z:~c. *t ow-^s, coerates c* '"as i^'.cre-s: m nn.-g oDeratior.s m Ida-.o, v.o~t = - =,
V.ashi-gtcn, arc 3n.:is'r Ccl.-rb:a. -iddiricn :o its Timing facilities, the Co-:ir"
i.:c c'^> cnd c:cr;:as or.~.arv s- '.j-icery lead inciters, u primary Zinc	*,
s_If_r;c c «d	- ac:d slants, .sad -manufacturing facilities ard a crenica. ,e;c
rrcc-CiT, _n:t. Vest of nese ocp-atiors are located here in the Coeur d'Aie^e cistrttrt,
-0~,. plants ^"d offices s:t-ctec or. tu.e Pacific Coast in Seattle, Portla~c, Cz<.i~z
a - X * n " ^ ""l C 0 1 3 .
The 3unker Hiii story began m the year 1885, five years before Idaho was *">
become a State. Tho olace was above the present town.site of Wardrer on Milo Cree-:.
Op crabout Seotember 10, 18S5, N'oah Kellogg or Phil O'Rourke, or Kellogg's burro,
ciscovered tr>: outcropping of what was to become the Bunker Hill Mine, the cor'-er-
3;cre of '.ocay's industrial complex.
Much controversy surrounds the discovery and early development of tie
Su-iVe- Hill Vii'i'i, end t^ere \s a multitude of colorful stories that could be relatec.
'-"c'Aever, suffice :t to say that tvvc major claims were first staked m Milo Gulch--
3"s was ramed t^e Bunker Hill after the famous Revoluuonary Battle and the other
vc3 nz~sd the SulLvan after Ccrnelius SulLvan, a close friend and creditor of ?'"il
0 Rourxe.
Thus, it was with these two runes m *uly of 1887 that the Bunker Hill a°d
S'.ilivan Mining and Concentratmc Company was incorporated under the laws of the
State of Oregon. In the brief period between the controversial discovery of the two
-ines and tre incorporation cf the Company, the properties were operated by t^e
:r:g:n,al owners and by the Helena Concentrating Comoany.
The early years of the Bunker Hill Company were filled with the usual r;'rtr-
cus trials and tribulations. And through these years, many great men of American
history pa-ticipated m pulling the CcmDany through — some as officers and managers,
ethers as najor stockholders who frequently loaned money for capital improvement:
Simeon G. Reed, first president of Bunker Hill and later the founder of Reed College
m Portland; John Hays Hammond and General N. H. Hams, early day Bunker Hill
presidents; W. H. and George Crocker of the famous San Francisco banking family
Cyrus H. v5cCormick of the American Harvester Company; James H. Houghteh^c o:
?eabody, -ioughtelmg & Company of Chicago- Daniel Guggenheim of Arrer.ca-
Smelting and R^fi^r.g Company fami=; and, of course, Frederick W. Bradley a-.c

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Stanly A. Easton, outatsnd.r.g min.r.g men dr.d president 'A 3_->-r Hili for ever
5 7 years. There were others, b_t the me-i hjv^ menticre:: al! r.a-	to piay ir
tne development of Burner Hill to :r.n company it today.
In 1898 Bunker Hill jo.nec v.*.tr. tr.c A-a^a TreaciwiM. r. ,..j in G'.rchaii.-.g a
controlling interest *n the Tacoma	-.n t.h< .-r.or^;,	3..-.C. b .
Hill's interest was 31-1/3%. ?r.or to th.s data, the cro from tr.e Bunker Hil: =r.c
Suhivan mines had oeer. sr.»pc60 rc 3.~*.ei"c-rj at s^cr. pliers -j /^'z s, Mtir.ti.rc.
Denver and Pueblo, Ccioraao; \ar.sai City, Missouri; a:.o iir, .r.;.3c.:, Ca..-
torn.a. The Tacoma Smelter m 1898 was> a It-ad smelter .n rath-, r dilapidated cor.c.-
t.on and in need of reconstruction. W.th tne steady flow of i-ad concentrates -re-
Banker Hill and gold-iron concentrates iron tne Alaska Treacwpji nes, the s-.e.rar
vji scon put on its fee: ana oecame a protitacie operation. Pr.tr to its sale ir L-jS
o the American Smelting and Refining Company, its lead sn:H\r.g department was re-
.abilitated ana a copper smelting aepartmen: was added.
When Bunker Hill's interest in tr.e Tacoma Smelter was sold 'o A3&R, a tv/er.ty-
ive year smelting contract was also negctiat.ec tor Sur.kyr Hill lecd concentrates.
low ever, when the smelter closed its lead plant in 1912, 3ur.ker Hi.i'j lead was
nipped to Selby, California, and East Helena, Montana, for processing, 5l: ci:':i-
ulties arose as a result of these cnar.ges and in 1916 Bur.kc-r Hiil started corstr-c-
on of its own lead smelter at Kellogg.
Erection of the Banker Hill Lead Smelter was the beyinr..:-.n of an import jr.;

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- 27-
The years L955 and 1956 were tn.e n.ext major periods in Bunker Hill exoa-.-
si3-i. In 1955 Hecla Mining Company's :-it<-<-est in the Sullivan Mining Company
wc>s secured for 2 75,000 shares of 3unker Hill stock. This action brought the II-
ectrolvt:c Zi".c ?lant, which had aiways been under Bunker Hill direction, i~:oc:c =
lar-o-"'/ with :ve Lead Smelter. It also brought into the Company's fold t^e Star ~i
mw'- Hecla o^ere::-c :'-«e o-coertv und^r contract. This Star mine arraignment v/as
c~ancec to -^a^e Hecla a 30% owner of the property in lieu of the opera::-';
Tne 1255 negotiations with Hecla also brought Bunker Hill 495,000 snares
of ?Q"d Creille Mi->es and Vietals Company stock, increasing Bunker Hill owners-.;:
of this Northeast Washington zinc-lead mining firm to 36%.
In 1956 the Northwest Lead Company, Bunker Hill's 92% owned lead rr,:-
farturm.g and secondary lead smelting facility m Seattle, was completely controlle:
end converted to tne Sales and Fabrication Division of the Company. Along v/:;.i
thfse numerous changes in the Ccmpany profile during 1955 and 1956, the corpora:*
-air.e was streamlined from the Bunker Hill and Sullivan Mining and Concentrat.-c
Comany to The Bunker Hill Company, me present name.
The Company's most recent expansion took place in 1960 when a 130-:cn p?
cav Phosphoric Acid Plant was constructed between the Smelter and Zinc Plant.
Due to an eight-month strike, the plant didn't go on stream until 1961 but today is
another integral operating unit of The Bunker Hill Company.
Cver the years these many expansions have increased corporate assets to
over S30, CC0,000--made the Company the nation's number two lead mining car oar.',
& refiner of nearly 24% of U. S. produced special high grade zinc and 20% of :ne
primary refined lead.

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-43-
BRIEF HISTORY AND PRESENT OPERATIONS OF THE
BUNKER HILL CONCENTRATOR
by
Norman J. Sat'ner, Superintendent of Concentration
The Bunker Hill ores mmeralogically contain galena, sphalerite , tetrahedrite,
:/r:te, sicerite, ankerite, arc cuartz.
The first mill had a capacity of 100 tons daily and began operations on July 20,
ii:5, exactly 77 years ago tcday. This mill was constructed near the portal of the
:esd Tunnel, which is located m Milo Gulch at Wardner, Idaho. The treatment was
/pole, corsisting of crushing to 2 inch and then to 1/2 inch through rolls m closed
crcuit with a bucket elevator ana trommel screens, the undersize of which was further
re:een.ed by trommels to 10 mm and 3 mm. Oversizes from the latter were each treated
p Kartz jics. The 3 mm undersize was classified m crude hydraulic classifiers furnish-
5cr.cs to sand jigs, the overflow being de-watered in a long "V" tank which supplied-
":c."ds tc a (Cornish buddle ana to a Frue vanner. The concentrates produced were approx-
\irr.elv 20 1ons per day, assaying an excellent grace of 69% lead and 29 ounces of sil-
ver. Tie tellings were high in lead because no good way to treat slimes was available.
7*3 procuct was hauled 12 miles by team to the Old Mission near Cataldo, or head of
r.av.cation on the Coeur d'Alene River, where it was transferred to boats, carried down
.-Lie river and thence across Coeur d'Alene Lake to Coeur d'Alene City where the con-
centrates were transferred to the Northern Pacific Railroad and shipped to the smelter
_=:Wickes, now East Helena, Montana.
As the known tonnage of ore increased, it was apparent that a mill of larger
capacity we's needed, and in 1891, a new mill of 400 tons capacity was built near the
rortal of th'2 present Kellogg Tunnel. It was called the "South Mill" and the ore was
ce nve re a to it by means of a 10,000-foot aerial tramway. An 8* x 6' wooden flume
brought wa*er 1-1/2 miles for milling and to turn the Pelton wheels which furnished
lie power to operate the mill.
The South Mill was destroyed by dynamite during the strike of 1899. The mil!
.¦/as rebuilt in 1900, with an improvement by adding Huntington mills for regnnd-^c
ne jig middlings.
Whon the Kpllnag Tnnnpl wp<; completed in 1902, the tramway was abancon?d.
A Crushing Plant was installed, consisting of two crushers, set of rolls and con.ve\or
goirg to storage. In this plant, crude shippirg-cre from the mill feed was hand seed
on a sorting belt until October, 1907, when the practice was abandoned.
By 1905, the tonnage had been raised to over 1,000 tons per day, well b-
normal capacity, which caused excessive losses in the tailings.

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-4 4-
The mill was under the cirectxcn of a young engineer, Gelasic Caetani, wi\o rerr.c.r.ec
as Mill Superintendent from 1905 to 1910. In 1906, Mr. Caetani commenced to re-
model the mill and replaced the buddies w.th V/ililey tables, and ir.iroauccc a r-,e:r.cc
of reconcentrating the jig concentrates by gr.ndirg tn.er. ir: a Hur.t.r,::on mil ar.c: -.red-
ing the ground product on tables producing a concentrate c.3say.ng 75% p'.us lied, ."or
which a premium was pe:c. This treatment resulted a largo product.or. z:
middlings for which the South Mill provioec no treatment. To correct this u:;u3t.orw
North Mill was built to treat tr.e old South Mill tailings: :t v/js orrang^c :o treat '_".c
excess of slimes and middlings by means of Huntington mils, taok s ar.c var.r.ars.
Mr. Caetani carried on his experiments :n 1906-1907 and lcid the grcur.c.'.c:<
in designing the first unit of tr.e Wast Mill which commenced operation on Noverce:
9, 1909.
Who was this colorful gentleman from Italy?
Prince Gelasio Caetani was from a distinguished Italian family, who, for rary
hundreds of years had been closely interwoven with the romantic history of Italy. After'
an early education m charge of a tutor, and after completing ms preparatory stucias,
he entered the University of Rone from whicn he graduated in 1901 with hign honcrsir.
Civil Engineering. About this time, his thoughts turned to mining and metallurgy a-.c
he soon developed a definite trena toward those two brancnes o: -fr.g-r.eering. Kav.rg
determined to carve out for himself an independent career, he studied for acout a ye=r
at the Mining School at Liege, Belgium. Before completing tne course, he cec^ed to
enter the School of Mines of Columbia University, New York C.ty. When 25 years o;
age, he graduated with high honors with the class of 1903 with a degree of Engiree:
of Mines.
After graduation, he headed West with letters of introduction to Stanly A. Easter.,
General Manager of the Bunker Hill organization. This large organization was firi e:%-
ceptionally good post-graduate training school for a young engineer, in which, tnrcugn-
out his years of faithful work, Caetani utilized every opportunity to perfect himself
the best engineering practice. Caetani's achievements during this period were ex-
pressed by Mr. Easton in these words:
Caetani was the first in the Coeur d'Alens Mining District,
and possibly in the West, to develop flowsheets for the treat-
ment of local ores by gravity concentration on the basis of
sound metallurgical practice, careful laboratory research and
experimentation - thereby actually determining the various pro-
ducts circulating in the Mill and discharged thcrpfrom, their
tonnages, mineral content, and physical qualities and especially
the economic as well as physical recoveries. This practice has
long been much perfected and is now standard in all up-to-date
milling operations.

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This hicK tribute to sc vcurc ar. engineer is further proof of Caetam'3 u^re-
acci.'cation to tne details of '".s *or'< curing the 5 years from 1905 to the clc3
cf 190'3 a: t-e Burner Hill. ?r:".cs Ceiasio Caetam's period of service with the
Hill CoTio^ny ca^e to an end sccr after the successful completion of *he r-ew
c
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-"6-
In 1947, the Concentrator, including the Sink-Float Plant, was c.-.l=.r.;-_c to hara.e
another 1,200 tons or from 1,800 tons to 3,000 tons per day. in February, 12 5 3, tie
Sink-Float Plant was shut down, Decausc of low rretal prices, which c--tdi.ec :-,c op-
erations underground to the caving project c: low-grace lead ar.c zinc ore.	r
operations today are at the rate of 2, 100 tens per operating day, liv- cays per wcj-'..
The old South Mill, mentioned previously, wen: -.r.ro^r tc.";' stagii o: j;-
eration after its closing in November, 1912, wr.en ceased :<> na-cie regular Butsc."
Hill ore. In June, 1913, it commenced treating Sierra-Nevada and Bunker HiL Lei£-
ors ore until June, 1914. At this time, tne mill was remccoled tc concentrate ere
the Caleaonia m adaption to the regular mill feed.
In September, 1915, :ne S.erra-Nevaca ore ceastc and a .small tonnage c:
Hill ore replaced *t. In 1917, a small tonnage of ore from tne Ontario nro v.as reed..:
for approximately six montns, after which the Sierra-Nevaca ore treatment was re".5
The Caldeonia ore ceased in Ja.nucry, 1913, and the Bunker Hill anc S.erra-Nevaca
supplied the tonnage until April, 1920, when tne mill was destrcyec oy ;i:e.
The mill was rebuilt and remodeled, and from January, 1925, the Star ere
Burke, Idaho, and ore from the Sidney mine in Pine Creek were- treated urt.l Apr..,
19 27. The mill was again remodeled tor all grinding and flotation to troat ta.Lngs ::::
the Sweeney Mill dump. This processing continued until Marcn, 1929, wh-n tr.e
operated again on Star mine ore for another year, to March, 19 30. For acprot'.-ate:1/
six months, to December, 19 30, the mill operated on tailings from the clc Scut" K~:
dump. The mill remained idle until July, 1933, when it startoc to treat B^n
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-51 -
THE BUNKER HILL SMELTER
by
A. F. Kroli, Smelter Suoenntendent
T'ne Bun'-cer Hill Smelter has treated mary tons of ores during these last
<5 /ears, from which have been produced:
Lead		2,903,504 tons
Silver		345,978,91 1 ounces
Gold		544,142 ounces
Copper		38, 709 tons
Antimony		28,280 tons
Zinc		310,718 tons
Cadmium		1,639 tons
Although, seme of the equipment and buildings are the original ones put
i-to service in 1917, there have been numerous changes over the last 46 years due
to improved metallurgy, production requirements, automation and cost reduction.
A few of the major changes, alterations or additions made were:
Lead Refinery was rebuilt.
Lead Refinery is being streamlined
Antimony Plant was constructed.
Slag Fuming Plant became operational.
Cadmium Recovery Plant was put into service.
Crushing Plant was constructed.
Ore Preparation or Pre-Sintenng Treatment Plant
was constructed.
Lead casting department was automated.
In addition to the above, many other changes have been made in the Lead
Shelter such as-
(1)	Larger blast furnaces.
(2)	Smoke and Fume recovery.
(3)	Vacuum Dezmcing refining.
(4)	Materials Handling improvements.
(5)	Continuous Softening Furnaces.
( )
1930 -

19 50-

1963 -
C)
1939 -
0)
194 3 -
(¦5)
1—>
CO
cn
1
(¦>)
1952 -
(o)
1952 -
(')
1958-

1963 -
Eot'i mechanical and metallurgical changes are continually in progress
.n order to k-ren the operations as modern as nossioie, thereby keeping us compe*

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Bunker Hill Mining & Metallurgical Complex
Mining Waste NPL Site Summary Report
Reference 4
Telephone Communication Concerning Bunker Hill Mining
and Metallurgical Complex; From Maria Leet, SAIC,
to Sally Martin, EPA Region X; October 22, 1990

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TELECOMMUNICATIONS
SUMMARY REPORT
SAIC Coritact: Maria Leet	Date: 10/22/90	Time: 1:15
Made Call	 Received Call X
Person(s) Contacted (Organization): Sally Martin (206) 442-2102
Subject: Hunker Hill Mining and Metallurgical Complex
Summary: Two Remedial Investigation/Feasibility Studies being prepared for the Residential/Populated
Area and the Nonpopulated Area (which includes defiant smelter).
•	Populated Area:
• ROD is expected in the second quarter of fiscal year 1991 (i.e., January to March 1991)
-	The Remedial Investigation was released last week On October 1990)
-	There will be a follow-up ROD for homes, interiors, and commercial properties 1 year after the
first ROD (i.e., expected in the second quarter of fiscal year 1992)
•	Nor.populated Area:
-	Completed data collection for Remedial Investigation
-	>;ow writing Remedial Investigation - due out in 1992.
A suit v/as filed re: response to Section 104 Request - No further action yet. An estimate of $100
million Tor final corrective actions is not unreasonable (although it is a ball park figure).

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Bunker Hill Mining & Metallurgical Complex
Mining Waste NPL Site Summary Report
Reference 5
Excerpts From Risk Assessment Data Evaluation Report
for the Populated Areas of the Bunker Hill Superfund Site;
Prepared for EPA Region X and the Idaho Department of Health
and Welfare by Terra Graphics; October 18, 1990

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SEPA
RISK ASSESSMENT
DATA EVALUATION REPORT
RADER
FOR THE POPULATED AREAS OF THE
BUNKER HILL SUPER FUND SITE
October 18, 1990
Prepared for
U.S. Environmental protection- Agency, Region X
and
Idaho Department of Health and Welfare
Printed on Recycled Paper
o

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soils, and dusts have been identified as contributors to elevated blood lead levels in
children living in the Bunker Hill project area. Environmental media concentrations of
site contaminants of concern in the Populated Areas are strongly dependent on distance
from the: smelter facility and industrial complex- Residential areas nearest the smelter
complex have shown the greatest air, soil and dust lead concentrations; the highest
childhocd blood lead levels; and the greatest incidence of excess absorption in each of
the studies conducted in the last decade.
During ±e period 1974 through 1990, childhood blood lead levels in the area have
ranged from approximately 1 /xg/dl to a high of 164 /xg/dl. The highest areawide blood
lead levels for children 9 years were reported in 1974 (median = 46 Aig/dl) and the
lowest ia 1990 (median = 8 /xg/dl). Two years after smelter closure, in 1983, more than
25% of preschool children in the most contaminated area of the site exhibited blood lead
levels greater than 25 Aig/dL It is estimated that since 1973 more than 1,000 children in
this community have experienced excessive absorption of lead (relative to the current
CDC /ig/dl criteria) and possibly other metals (JEG et aL, 1989).
The he:dth effects of environmental contamination were first documented following the
period of extreme smelter emissions in 1973 and 1974. Up to 75% of the preschool
children tested within several miles of the complex had blood lead levels exceeding CDC
criteria Several local children were diagnosed with clinical lead poisoning and required
hospitalization. Lead health surveys conducted throughout the 1970s confirmed that
excess blood lead absorption was endemic to this community. Concurrent epidemiologic
and environmental investigations concluded that atmospheric emissions of particulate
lead from the active smelter were the primary sources of environmental lead that
affected children's blood lead levels prior to 1981. Contaminated soils were also found to
be a significant, however secondary, source of lead to children in the 1970s.
An analysis of historical exposures to children who were 2 years old in 1973 suggests a
high risk to normal childhood development and metal accumulation in bones due to
1 - 19

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extreme exposures that could offer a continuing lead body burden in these children due
to its long physiologic half life. Females who were 2 years of age during 1973 are now of
child-bearing age, and even with maximum reduction in current exposure to lead, the
fetus may be at risk due to resorption of bone lead stores in the young women (JEG
et aL, 1989).
Following smelter closure in late 1981, airborne lead exposure decreased by a factor of
10, from a sitewide average of approximately 5 pg/m3 to 0.5 /ig/m3. A 1983 survey of
children's blood lead levels demonstrated a significant decrease in community exposures
to lead contamination. The survey also found that several children, including some born
since 1981, continued to exhibit blood lead levels in excess of recommended public health
criteria. Accompanying epidemiological analyses suggested that residual contamination in
soils and dusts represented the most accessible sources of environmental lead in the
community. The potential hazard presented by these sources and the indication of
continued health risk experienced by the community were major considerations in the
USEPA's and IDHWs decision to initiate RI/FS activities for the Bunker Hill project
area.
Childhood mean blood lead levels have continued to decrease since 1983. These
decreases are likely related to a nationwide reduction in dietary lead; reduced soil, dust
and air levels in the community, intake reductions achieved through denying access to
sources; and the increase in family and personal hygiene practiced in the community.
The latter is reflected in the implementation of a comprehensive Community Health
Intervention Program in 1984 that encourages improved hygienic (housekeeping)
practices, increased vigilance, parental awareness and special consultation on individual
source control practices such as lawn care, removals, and restrictions. The Community
Health Intervention Program was initiated specifically to reduce the potential for excess
absorptions and minimize total absorption in the population until initiation of remedial
1 - 20

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activities. Total blood lead absorption among the community's children has been reduced
nearly 50% since 1983. The incidence of lead toxicity (blood lead > 25 jig/dl) has fallen
from 25% to less than 5% of children in the highest exposure areas.
sorrrmaii pc/jac
1 - 21

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Graveled areas, particularly those used as parking lots, showed significant
recontaminauon. Because of the low rates of surface deposition, these increases likely
resulted from the continual working of the original soil layers below the replacement
materials or tracking of contaminants onto the site by vehicles.
2.12 Residential Soils
2.1.2.1 1986-87 Residential Soil Survey
Extensive sampling of yard soils for the RI/FS was initiated in the 1986-87 Residential
Soil Survey. The communities of Smelterville, Kellogg, Wardner and Page were surveyed
in Phase I RI efforts 1986-87. Pinehurst and the additional residential area of Elizabeth
Park (immediately east of the project boundaries) were completed in 1989 in part of the
Phase II RJL
In both surveys, properties were tracked according to Shoshone County property tax
records. Maps and master lists of all properties in each municipality were obtained in
advance of survey activities. Every home in the Phase I communities, was targeted for
sampling. Field crews attempted to contact each homeowner/resident to obtain
permission to sample. If permission to sample was granted, samples yere secured. If the
homeowner or resident refused, the response was noted and the property was bypassed.
If the homeowner or resident could not be contacted in three successive visits or if the
home was vacant, the property was bypassed.
A composite mineral soQ and litter sample was collected from pre-selected locations in
each yard. Eight 3/4-inch-diameter soil cores were obtained, four from each of the front
and backyards. Samples of the top one inch of mineral soQ and litter (decaying
vegetative material and sod above the mineral soil horizon) were composited separately
for laboratory processing. Samples were processed according to current EPA Contract
Laboratory Program (CLP) procedures and analyzed for the following metals: antimony,
arsenic, cadmium, chromium, copper, lead, manganese, mercury, nickel, selenium and
zinc.
2 - 13

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Details cf the sampling and laboratory protocols can be found in TG, 1986c; CH2M
HILL, l!>90a; and TG, 1990.
In total, more than 64% of all homes in the Phase I communities were sampled in the
1986-87 survey. Table 2.4 summarizes metals concentration by town for the 1986-87
survey for soils and litter. Figure 2.1 shows the frequency distribution for soil lead levels
for each community. More than 85% of the properties in these four cities exceed the
500-1,003 /ig/gm lead warning criteria cited by CDC for-lead in soils (CDC, 1985).
Current directives advise using 500 to 1,000 /ig/gm lead in soil as a cleanup criteria in the
absence of site-specific dose-response information (USEPA, 1989a). Approximately,
1,000 to 1,250 homes in Phase I communities are candidates for eventual remediation by
this criteria.
Residential soil survey data were prepared at community meetings in October of 1988.
Homeowners and residents were notified of their individual property*results and invited
to a public forum for further explanation and discussion. For public presentation, it was
necessary to use maps and displays that contained no identifiable individual results. To
meet th.it confidentiality requirement, neighborhoods based on legal subdivisions were
defined and summary statistics were developed for geographic areas within the cities.
Figures 2.2 and 2.3, show non-confidential maps developed to publicly present residennal
yard soil contamination levels for Smelterville and Kellogg. Table 2.5 shows the overall
summaiy tables from these maps for Smelterville, Page, Wardner, and Kellogg.
There are 2,236 total parcels and 1,547 homes in these areas; 1,020 (64%) of the homes
were sampled in the 1986-87 effort. In order to present health risk concepts and to
provide citizens with an idea of how their individual results compared to their neighbors
and possible health criteria, properties were summarized according to three categories of
risk based on soil lead concentrations. Table 2.5 shows, per the example criteria, that
5% of the homes in Smelterville had acceptable soil concentrations (<500 fig/gm Pb),
14% were recommended for individual consideration (500-1,500 /xg/gm Pb), and 81%
2 - 14

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Table 2.5
Residential Yard Sapling Status
and Lead Caitalnition Staaury
by Tomti (Phase I RI)
Kellogg*
#	residences	1076
t sampled	677
Avg Sot I Pbt^jg/^n)	2800
t < 500 &/go	2%
*	500-1000 tf/ga	9%
V > 1000 pg/> 21%
\ >1000 tMj/ga	69k
Smelterville
#	residences	271
t sampled 200
Avg Soil Pb(t4/ga) 3700
% < 500 i*}/ga St
% 500-1000 xg/?s 7%
*	> 1000	83*
Page
f residences	65
I sampled	51
Avg Soil Pb(«g/gn)	1042
% < 500 t^/ga	27%
% 500-1000 (4/ga	36*
* > 1000 Mg/gn	37*
* Includes Ross Ranch.
All Sites - Combined
*	residences	1543
t sanpled 1020
Avg Soil Pb( iooo	S4%
were candidates for remediation (>1,500 /ig/gm Pb). Similar results can be obtained for
Page and Wardner or specific neighborhoods in Kellogg and Smelterville from Figures
22 and 2.3.
2.1.2^ 1989-90 Residential Soil Removal
Additional residential properties were sampled in 1988-90 as part of emergency removal
activities accomplished in the summers of 1989 and 1990. Eighty-one yards and two
apartment complexes were remediated in 1989 as pan of a program to reduce exposures
to young children and pregnant women in the Phase I communities. Residences were
selected for remediation based on the combination of the residence housing a pregnant
woman or child under three years of age and having an excessive soil lead level. The
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program was continued in 1990 and extended to homes with children under nine years of
age. An estimated 130 additional homes have been remediated in the dimmer of 1990.
Removals have consisted of a one-foot excavation and removal of yard soils, replacement
with clean top soil, sodding, and replacement of the yard features to original condition.
Garder. locations were excavated to depths of 18 to 24 inches and then replaced with a
clean layer of top soil.
Approximately 15% of these homes were not surveyed in the 1986-87 effort and samples
were obtained as part of the removal efforts. These results were not included in
Tables 2.4 and 2-5 or Figures 2.2 and 23 because of differences in sampling methodology
and reporting of results. Table 2.6 summarizes the removal effort by town for 1989-90.
2.1.23 Pinehurst and Elizabeth Park
The Ciiy of Pinehurst and the unincorporated residential area of Elizabeth Park were not
included in the original 1986-87 Residential Soil Survey. Previous soil and blood lead
surveys had indicated that these areas were at substantially lower risk to excess
absorption than those in the Phase I communities. Residential soils in Pinehurst and
Elizabeth Park were sampled in 1989.


Table 2.6



Sumary of Properties Remediated in 1989-90 Keanrals


1989

1990
Town
1 of Properties
Range of Pb levels
# of Homes
Range of Pb Levels
Remediated
in Soils Replaced
Remediated
In Soil Replaced
Kellogg
56
<54-10400 (jg/gn
98
500-24500 vq/qa
SmeUerville
17
356-8250 tQlgn
21
500-12800
1 Pa9e
3
1500-1640 ««j/gn
3
500-1510 ng/gd
Wardner
S
587-876 jjg/gm
16
500-22700 «g/grc
2 - 22

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routinely exhibited levels in excess of 2% lead. Percent of sample solids to pass 200-
mesh ranged from 6 to 68%, averaging 30% for all samples.
The metals concentrations and silt content levels exhibited are extremely high.
Consequently, these sources are a major health concern for the area. They represent
both a direct contact hazard to humans accessing the sites and are, likely, primary
sources of continuing contamination to soils and household dust media in the Populated
Areas. Emission rates and potential impact estimates have been developed for these
sources and are presented in Section 4 of this report as contaminant fate and transport
issues.
22 Results of Air Investigations
2-2.1 Air Quality Monitoring
2.2.1.1 NAAQS Monitoring
Ambient air monitoring for Total Suspended Particulates (TSP) and lead have been
conducted at the Bunker Hill Site pursuant to National Ambient Air Quality Standards
(NAAQS) since 1971. These data have been summarized in JEG et al., 1989.
Table 2.11 shows historical TSP and lead results for the site. Figure 245 shows historical
lead concentrations for select stations. Ambient lead loadings were significantly higher
during smelter operations years and particularly in 1973-74 when smelter air pollution
control was defective. Figure 2.6 shows monitor locations for the several studies
discussed in this section.
Since smelter closure, ambient TSP and lead levels have generally been within primary
NAAQS requirements. TSP values ranged from 30 p:g/mJ to 70 jtg/ni3 on an annual basis
with daily values ranging to 900 jig/m3. Atmospheric lead concentrations have ranged
from 0.1 ng/m* to 0.5 fig/m3 on a quarterly basis ^th daily observations as high as
2.8 jig/m3. Particulate levels vary on a seasonal basis with the highest levels observed m
July through October. Secondary peaks are noted in late winter or early spring,
2 - 34

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3.1 Soiil and Dust
There are currently no promulgated laws or standards which provide numerical
thresholds, that serve as ARARs for soil and dust contamination. However, TBCs have
been developed that address threshold levels of lead in soil and dust. These TBCs
include:
•	Centers for Disease Control (CDC) Soil/Dust Lead-Contamination
Advisory, Preventing Lead Poisoning in Young Children: A Statement
from the Centers for Disease Control. Atlanta. U.S. Dept. of Health and
Human Services, January 1985.
•	USEPA Guidance Concerning Soil Lead Cleanup Levels at Superfund
Sites, OSWER Directive #9355.4-02- Office of Solid Waste and
Emergency Response, September 1989.
CDC's 1935 statement on childhood lead poisoning provides the following guidance:
"In general, lead in soil and dust appears to be responsible for blood levels in
children increasing above background levels when the concentration In the soil or
du:,t exceeds 500-1,000 ppm."
This advisory is consistent with the September 1989 USEPA (1989a) ipterim directive
concerning soil lead cleanup levels at Superfund sites.
Data representing lead levels in residential yard soils are available from the 1986/87
Bunker Hill Populated Area RI/FS (CH2M HILL, 1990a; see Section 4 of the PD and
Section 2 of this report). The reported concentrations are compared to the CD CI
USEPA soil lead target levels in Table 3.1. Mean background level of soil lead is also
provided in Table 3.1 for comparison. Figures A3.1 through A3.3 and Table A3.1 in
Appendix A present soil lead concentration statistics and distributions since 1983.
Approximately 95% of the residential yard soil lead concentrations in Smelterville,
Kellogg, Wardner and Page are greater than 500 ftg/gm (ppm) and approximately 85% of
the yard surficial soil lead concentrations are greater than 1,000 ;ig/gm. A 1989 survey of
Pinehurst residential soils shows that approximately 50% of the soil lead concentrations
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3.0 SITE-SPECIFIC CONCENTRATIONS OF CONTAMINANTS OF CONCERN
COMPARED TO ARARs AND TBCs
State and federal ARARs (applicable or relevant and appropriate requirements) and
TBCs (to-be-considered materials) for the Populated Areas of the Bunker Hill site are
identified and discussed in Section 6 of the PD (JEG et al., 1989). ARARs and TBCs
Eire generally referenced as cleanup standards and/or guidelines for remedial actions at
Superfund sites. The chemical-specific ARARs and TBCs presented in this section are
those that are expected to be protective of public health.-
Site-specific concentrations of contaminants found in environmental media of the
Populated Areas are compared to ARARs, when they are available. In addition to the
laws and regulations, many federal and State environmental and public health programs
also develop criteria, advisories, guidances and proposed standards that, although not
legally binding, may provide critical health-based information or recommendations.
These materials are referred to as "to be considered" (TBC) materials. In specific cases,
a risk assessment can be based on the application of health-based criteria derived from
TBCs.
ARARs and TBCs referenced in this section are a subset of all chemical-specific ARARs
and TBCs identified for the Populated Areas. Only the standards and guidelines that
provide specific numerical values, and for which there are comparable site data, are
presented. For several of the chemicals of concern and relevant media pathways,
appropriate ARARs or TBCs do not exist. In those instances, the risk assessment
process will be used to establish cleanup goals. Site-specific data regarding blood lead
levels in the resident childhood population are also discussed with consideration of recent
health-based guidances' concerning lead absorption in children.
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3£ Blood Lead Levels
An evaluation of representative blood lead levels for children of the Bunker Hill site, in
consideration of the appropriate health-Upsed guidances and criteria, is presented here to
further assess the risk posed to human health by site contamination. The following are
considered in this regard:
•	Centers for Disease Control (CDC) Soil/Dust Lead-Contamination
Advisory, Preventing Lead Poisoning in Young Children: A Statement
from the Centers for Disease Control. Atlanta. U.S. Dept of Health and
Human Services, January 1985.
•	Agency for Toxic Substances and Disease Registry (ATSDR) Report to
Congress, The Nature and Extent of Lead Poisoning in Children in the
United States: A Report to Congress. ATSDR, Public Health Service,
U.S. Dept. of Health and Human Services, July 1988.
•	USEPA's Review of the NAAQS for Lead, Review of the National
Ambient Air Quality Standards for Lead: Assessmentof Scientific and
Technical Information. USEPA. March 1989.
« USEPA's Proposed Rule for Lead in Drinking Water, 53 CFR 31516
(August 18, 1988).
•	USEPA's Clean Air Scientific Advisory Committee (CASAC) Report,
Report of >the CASAC On Its Review of the OAQPS Lead Staff Paper and
the ECAO Air Quality Criteria Document Supplement.
EPA-SAB-CASAC-90-002, January 1990.
CDC's Health Advisory for Blood Lead Levels states that "a blood lead level in children
of 25 /ig/dl or above indicates excessive lead absorption and constitutes grounds for
medical intervention." This advisory level, however, may be superseded for the
protection of public health due to recent information indicating adverse health effects
associated with blood lead levels at 10 to 15 fig/dl, or possibly lower. As a result, CDC
has indicated that consideration is being given for identifying 10 /xg/dl as a community
action le vel and 15 ^g/dl as the level requiring child placement in a follow-up health
prograrr (USEPA, 1990b). Both the USEPA and ATSDR have published recent
3-18

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32 Air
32.1 Oean Air Act (CAA), 42 U.S.C. Sections 7401 et seq.; National Ambient
Air Quality Standards (NAAQS), 40 CFR Part 50.
The Qean Air Act, and standards promulgated pursuant to the Act, the NAAQS, have
been identified as potential ARARs for the Populated Areas of the Bunker Hill site (see
Section 6 of the PD).
3.2.1.1 NAAQS for Chemicals of Concern
Ambient air quality data for the site is presented in Section 4 of the PD (JEG et aL,
1989). Ambient air concentrations for lead and total suspended particulates (TSP) since
1971 are reported in Table 2.11 as results obtained from the Idaho Air Quality
Monitoring Network, operated by the Air Quality Bureau of the Division of Environment
of the Department of Health and Welfare. Ambient air concentrations for some of the
other chemicals of concern have been estimated by developing metal-to-lead ratios
utilizing air quality and dust data from various site studies (USEPA, 1989i; Cooper et aU
1980; Ragaini et aln 1977; WCC, 1986; Dames &. Moore, 1990a; and CJH2M HILL,
1990e). Estimated mean airborne metal concentrations are compared to background air
quality data and presented in Table A3.2.
Lead is the only chemical of concern with an identified NAAQS. The NAAQS for lead
is a 3-month (quarterly), arithmetic mean concentration of 1.5 jig/m3. Comparison of the
standard to recent air measurements for lead (in Table 2.11) shows the site to be in
conformance with current regulations.
The USEPA has recently proposed a revision to the NAAQS for lead (USEPA, 1989c).
The suggested revision lowers the NAAQS to a monthly average of 0.5 pig/m3. The
reassessment of the NAAQS for lead considers an evaluation of alternative standards
based on the health risks associated with children's blood lead levels at and above
3-6

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documents (see references cited above) which conclude that adverse health effects are
associated with blood lead levels as low as 10 figfdl, 00 apparent threshold. CAS AC
(USEPA, 1990a) has also indicated that health effects associated with blood lead levels
above Id /xg Pb/dl in sensitive populations clearly warrant concern. The value of 10 Aig/dl
refers to the maximum blood lead permissible for all members of sensitive groups, and
not population mean or median values. CASAC recognizes that there is no discernible
threshold for several health effects associated with lead absorption and that biological
changes can occur at levels lower than 10 fig Pb/dl blood. Given that lead is a toxin with
no beneficial biological function, CASAC strongly recommends a public health goal of
minimizing the lead content of blood to the extent possible through reduction of lead
exposures in all media of concern.
The blood lead levels reported for children at the site are discussed in detail in the PD
(see Sec:ions 3 and 5). In 1989, 275 children (ages 9 years and younger) from
Smelterville, Kellogg, Page and Wardner were monitored in an areawide health survey.
Of the children tested, approximately 3% exhibited blood lead levels,at or above the
25 /xg/dl CDC (medical intervention) advisory level. Approximately 26% of the children
exhibited blood lead levels greater than or equal to 15 pig/dl; 56% exhibited blood lead
levels wliich were greater than or equal to 10 /tg/dl. In 1989, the median (50th
percentile) childhood blood lead level was 10 jig/dl. The 90th percentile level for the
study was 18 /xg/dl and the highest blood lead level among those tested was 41 /xg/dl. In
1990, 25 5 children were tested for blood lead in the same communities. Two (2) children
exhibited blood lead levels greater than or equal to 25 pig/dl. Forty percent (40%) had
levels greater than or equal to 10 /xg/dl and 14% were greater than or equal to 15 ptg/'dl.
The moj t recent health survey conducted in 1990 also included 107 children from
Pinehurst. Approximately 11% of the children exhibited blood lead levels greater than or
equal to 15 jig/dl; and 37% exhibited blood lead levels which were greater than or equal
to lOjig/dl. The median childhood blood lead level was 8 jig/dl. Survey results for the
population excluding Pinehurst (representing the same population group as in 1988 and
1989) showed generally lower blood lead levels than in preceding years; approximately
3-19

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1% of the population exhibited blood lead levels 25 ng/di, 15% 15 jig/dl, and
approximately 40% 10 (xg/dl. The highest blood lead level among those tested was
found in Smelterville at 30 p,g/dl. The lowest community mean blood lead level was
found in Pinehurst at 6.7 pg/dl (median = 6 ng/dl).
Bormmwi-pdyac
3-20

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Bunker Hill Mining & Metallurgical Complex
Mining Waste NPL Site Summary Report
Reference 6
Excerpts From Public Health Advisory,
Bunker Hill Superfund Site, Industrial Complex Portion,
ATSDR; October 5, 1989

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OCT 6 1939
Th'j Honorable William K. Reilly
Administrator
U ?. Environmental Protection Agency
401 M Street, S w.
Washington, D.C. 20460
De.ir Mr Reilly:
This is in reference to a Public Health Advisory for potential exposure to
ha:ardous materials and potential contact with physical hazards associated
wit:h the Bunker Hill Site, Kellogg, Idaho. The Agency for Toxic
Substances and Disease Registry (ATSDR) has evaluated the available
information for the areas encompassing the former smelter complexes at tr.e
Bunker Hill Site and has determined that the site poses a significant risk
to 'human health. We, therefore, recommend that {1) the Environmental
Protection Agency (EPA) immediately take steps to restrict access to the
si*:e and (2) suspend all salvaging operations until a Site Safety Plan,
including specific salvaging safety procedures, are approved and
implemented.
Enclosed is the Public Health Advisory that expresses our health concerns
and our recommendations to evaluate and mitigate or eliminate the risk to
huiian health. By separate letters, we have notified the BPA Region X
Administrator and the State of Idaho Department of Health and Welfare
about this advisory.
Enclosure
cc
Idaho Department of Health and Welfare
PHI! Regional Office
<_AT:;dR Region X
ATJ5DR/W
OD
OGC
CDC/VJ
Assistant to Director for Field Activities
er R. Dowdle
wMxer R. Dowdle, Ph.D.
Acting Administrator

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AGENCY FOR TOXIC SUBSTANCES AND DISEASE REGISTRY
DIVISION OF HEALTH ASSESSMENT AND CONSULTATION
PUBLIC HEALTH ADVISORY
BUNKER HILL SUPERFUND SITE
INDUSTRIAL COMPLEX PORTION
KELLOGG, SHOSHONE COUNTY, IDAHO
OCTOBER 5, 1989
INTRODUCTION
Curing the preparation of an Addendum to the Preliminary Health Assessment
for the Bunker Hill Superfund Site, Kellogg Idaho, the Agency for Toxic
Substances and Disease Registry (ATSDR) has determined that the Bunker Hill
Industrial Complex represents a significant risk to public health because
cf the potential for adverse health effects that may result from exposure
to chemical hazards and contact with physical hazards at the site. The
risks to human health posed by this site include: (1) potential for severe
toxicological effects resulting from acute exposure to arsenic from the
copper flue dust piles; (2) potential for adverse health effects resulting
from acute exposures to significant concentrations of lead, cadmium,
arsenic, and asbestos; (3) potential for adverse health effects resulting
from chronic exposures to significant concentrations of lead, cadmium,
arsenic, and asbestos during salvaging operations or other events on-site;
and (4) physical injuries that may result from contact with areas of the
SLte that pose physical hazards because of unrestricted access. For these
reasons, the ATSDR recommends that actions be taken immediately to
(1) restrict access to the site and (2) suspend all activities, including
salvaging operations, until a Site Safety Plan and specific salvaging
safety plans, are approved and implemented.
The purposes cf this public health advisory are to notify the
U.S. Environmental Protection Agency (EPA), the Idaho Department,of Health
aid Welfare (IDHW), and the public that a significant risk to human health
esists at the Bunker Hill Industrial Complex, in Kellogg, Idaho, and to
bring to their attention the ATSDR's concerns and recommendations to
protect the public health.
B ^CKGROUND
The Bunker Hill Superfund Site, which includes surrounding communities,
covers an area of approximately 21 square miles. This advisory concerns
ouly the areas of the lead smelter complex, the zinc smelter and cadmium
plant complex, and other industrial buildings/areas, and does not address
the residential or commercial areas of Kellogg, Pinehurst, Page,
Snelterville, and Wardner. The Bunker Hill Industrial Complex is composed
o: integrated mining,-milling, and smelting complexes that include the
Bunker Hill mine, a mill and concentrator, the lead smelter, the zinc
snelter, an electrolytic zinc plant, a phosphoric acid and fertilizer
p.ant, a cadmium plant, and sulfuric acid plant.

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Bunker Hill Mining & Metallurgical Complex
Mining Waste NFL Site Summary Report
Reference 7
Excerpts From Summary of Bunker Hill Remedial Investigation/
Feasibility Study, Tasks 0 through 16;
Dames & Moore; December 18, 1990

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TASK 2: SURFACE WATER AND AQUATIC BIOLOGY INVESTIGATION
The purpose of Task 2 was to characterize the distribution of contaminants of concern in site
surface waters for use in evaluation of remedial measures. Pursuant to the Work Plan, Task 2 activities
were civided into nine subtasks. Subtask 2.1 involved the initial field survey for identification of potential
problem areas and selection of sampling locations. Water-quality measurements under extremes of hiyh
and lew stream flow conditions and rainfall events were made during Subtask 2.2, while baseline
monitoring intended to bracket the extreme conditions was conducted under Subtask 2.3 How gaging
stations along the SFCDR, Bunker Creek, a-d Government Gulch were established and flow data were
collected under the Subtask 2 4 Stream-bed sediment samples were collected and analyzed during Subtask
2 5, and the effects of vegetation on erosion potential on hillside slopes were studied under Subtask 2 6
Subtask 2.7 involved preparation of the "Task 2.0 Data Evaluation Report (DER)" (PD169/27110
submnted September 6, 1989), while Subtask 2 8 addressed possible Phase II sampling designed to refine
source identification data. Subtask 2.9 consisted of an investigation of aquatic ecology and toxicology
Project deliverables lask 2 lnclui'd ten data report* containing the Phase I surface water and
stream sediment data collected manually or by automatic samplers from a network ot thirty-ihres
monitoring stations on the SFCDR and it tributaries. The "Technical Memoranda-Preliminary Data
Interp -elation Reports Nos 1 through 3" (PD100/2702 submitted July 8, 1988, PD 119/2705 submitted
October 21, 1988, and PD151/27080 submitted Apnl 7, 1989) provided evaluations of water-quality data
for thf period from September 1987 through May 1988 The Task 2.0 DER summarized the findings of
the preliminary data interpretation reports and incorporated Phase II data to characterize seasonal variations
in site water quality. The "Technical Memorandum: Revised Data Evaluation Report for Aquatic Biology
Sampling, Subtask 2.9: Aquatic Ecology and Toxicology" (PD 142/29300 submitted November I, 1989)
summinzed the data and findings of the aquatic biology investigations.
No contaminants of concern other than those delineated in the SCR were identified during Task
2 activities The Task 2 0 DER identified arsenic, cadmium, lead, copper, mercury, and zinc as being
amonr the contaminants of potential human health and environmental concern in surface water and
sediments under base-flow and/or transient high-flow conditions The following primary sources of
surface-water contaminants were identified.
o	Base-flows in the SFCDR from upstream of the sue boundary;
o	Ground-water seeps located on the north of 1-90 near the CIA,
o	Transient high-flows from Government Gulch and Bunker Creek;
o Diffuse ground-water inflows to gaining reaches of the SFCDR.
Task 16\Tasksum.rpt
Page 4'

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TASK 3: GROUND-WATER INVESTIGATION
The purpose of Task 3 was to characterize the site hydrogeologic regime, assess the distribution
of contaminants of concern, identify potential contaminant sources, and quantify contaminant loadings to
ground water The scope of Task 3 activities was divided into eight subtasks in accordance with the Work
Plan A survey of existing water wells and data review was completed under Subtask 3 I. Geophysical
surveys were conducted during the Subtask 3 2 investigations. A network of monitoring wells, lysimiters,
and piezometers installed and sampled under Subtask 3 4., and pumping tests in existing and newly
installed wells were conducted u~der Subtask 3 3. Water level data were collected over a period or one
year under Subtask 3.5, and chemical and physical parameter testing was performed under Subtask 3 6
Numerical modeling of ground-water flow and contaminant transport was performed during Subtasks 3 7
and 3 8 respectively Area-specific ground-water investigations were also conducted under Tasks 6, 7,
and 8 of the RI.
Task 3 d?'a reports containing the results of geophysical investigations (PD024/32080 submitted
7, 198/), t-'uup testing and addenoum (PD094/33030 «nhmittea February 14, 1989 ), and chemical
and physical pa.^meter testing '7D083/36020 submitted Apnl 21, 1988) from over 70 borings and
monitoring wells were submitted The "Task 3 Technical Memoranda Preliminary Data Interpretation
Nos 1 through 3" (PD107/34220 submitted August 15, 1988, PD126/34260 submitted December 7, 1988,
and PD 145/34300 submitted Apnl 4, 1989) provided evaluation of ground-water data collected throughout
the investigation. The "Task 3 0 Final Hydrogeologic Assessment" (PD134/37070) to be submitted in
January, 1991, will provide a site-wide evaluation of ground-water flow, estimates of ground-water source
loadings, and potential contaminant transport/exposure routes in ground water. A "Conceptual Model
Report and Consolidated Preliminary Response to Comments for Tasks 3, 6, 7, and 8" (PD175/373 10
submitted October 10, 1989) was also submitted under Task 3 deliverables.
Subsurface investigations revealed that the unconsolidated fill material in the SFCDR Vallev
comprises the dominant ground-water system at the site. Valley water-bearing materials consist of three
distinct fill deposits (1) the lower alluvial zone, (2) the upper alluvial zone, and (3) a confining layer or
lacustrine (lake sediment) deposits which separates the upper and lower zones. Tributary stream basins
contain colluvial and alluvial water-bearing zones capable of recharging the upper and/or lower zones or
the valley ground-water system. Other sources of recharge to the upper zone identified during Task 3
include inflows from upgradient, inflows from losing reaches of the SFCDR, infiltration of incident
precipitation, hillside runoff, leakage from abandoned wells and from the lower zone, and seepage from
various tailings and surface water impoundments. In addition to tributary flows, sources of recharge to
the lower zone include inflows from upgradient, leakage from abandoned wells and upper zone and
bedrock seepage
Site ground-water quality was characterized using Task 3 analytical data. The elements arsenic,
cadmium, lead, cobalt, and zinc were identified as contaminants of potential human health and
environmental concern in ground water. Other contaminants of concern identified in the initial SCR
including antimony, beryllium, copper, mercury, selenium, and silver were detected in site ground water
only intermittently and in concentrations near or below quantifiable limits. Primary sources of ground-
water contamination identified during the site hydrogeologic assessment include:
o seepage from the CIA pond;
o ground-water inflows across the eastern, upgradient site boundary;
Task 16\Tasksum.rpt
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Task 3 Hvdrngeolugic Assessment (Concluded)
o infiltration through valley-wide deposits of jig tailings; and
o ground-water flow through valley-wide deposits of jig tailings.
Other sources include discharges to the upper zone from Magnet Gulch, Pine Creek, and Milo Gulch,
infill ration of incident precipitation through CIA material other than the ponded area of the east cell, and
seepage from Sw^-ney Pond, McKinley Pond, and other surface-water impoundments
Only small net changes in ground-water quality were observed between upgradient monitoring well
GR-44 and the downgradient wells GR-26U and GR-26L. However, ground-water contaminant sources
within the site locally impact ground-water and surface-water quality through point and nonpoint loadings
No contaminants of concern other than those delineated in the SCR were identified during Task 3 of the
RI
Task 16\Tasksum.rpt
Page 6

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TASK 5: VEGETATION AND TERRESTRIAL BIOLOGY INVESTIGATION
The purpose of Task 5 was to compile and evaluate site growing condition data to assess the
prospects for natural and remedial revegetation and to identify potential growth-limiting factors The scope
of Task 5 was divided into nine subtasks. Subtasks 5.1 and 5 2 consisted of data collection and evaluation
to characterize site vegetation according to vegetation attributes such as foliar cover, species density,
species diversity, plant growth rates, and tree and shrub ages and sizes. Seasonal changes in plant cover
were investigated under Subtasks 5 1 and 5 6 using geographical information and mapping systems (GIMS)
thai employed Landsar, aenal photograph, and field survey data. Data from past revegetation projects
were evaluated under Subtask 5.3 An evaluation of vegetation growing condition analysis was provided
in a data evaluation report prepared under Subtask 5 4 Subtasks 5 5 through 5 9 involved the collection
and analysis of plant, small mammal, and insect tissues in order to evaluate the uptake of contaminants of
concern Characterization of site terrestrial fauna was conducted under these subtasks by field surveys,
tapping, and literature reviews.
Twelve t^rhnical memoranda, twelve data reports, ¦'nd two data evaiuai.c- reports were vutted
to EPA under Task 5 The "Revised Data Evaluation Report: Vegetation Growing Conduior analysis
Subtask 5.4" (PD160/54036 submitted May 14, 1990) provided a comprehensive characterization of plant
growing conditions at the site. The "Revised Task 5 Data Evaluation Report. Terrestrial Biology"
(PD168/59160 submitted September 21, 1989) documented the results of the Subtask 5 7, 5 8, and 5 9
investigations
The site was characterized according to five vegetative cover groups delineated by 1986 Landsat
Imagery and ground-truthmg These vegetation groups included A (0-5% cover), B (5-25% cover), C (25-
50% cover), D (50-85% cover), and E (85-100% cover). The percent of each unit covered by these
vegetative groups was calculated using Landsat in conjunction with GIMS.
Task 5 investigations concluded that site vegetation has been modified by a combination of minin;:
activities; logging, forest fires; and emissions from the Lead Smelter, Zinc Plant, and Phosphoric
Acid/Fertilizer Plant The major ecological change on the RI/FS site has been the replacement ot closed
coniferous forests by open scrub and woodland communities that contain extensive areas of barren and/or
sparsely vegetated soils. Approximately 1,424 acres of the unpopulated Hillside subarea of the Superfund
site consist of barren areas or disjunct plant communities of vegetative cover groups A and B locaied
predominantly south, southwest, and southeast of the Zinc Plant and Lead Smelter, i e , hillsides from
Grouse Creek eastward to Deadwood Gulch This area was delineated by the U S EPA in March or (990
as ihe growing conditions map window requiring more detailed study during Subtask 5 4 activities
Approximately 1,697 acres of the Hillside subarea in vegetative cover group C occur south and souther
of the Smelter Complex and on the south-facing slopes on the north side of the valley floor
Growing condition analysis, conducted by compiling all pertinent information into GIMS, maic Jied
that arsenic and heavy metals concentrations in some areas of Government Gulch and the lower hillside
areas extending from Grouse Creek to Deadwood Gulch could inhibit the growth of revegetaied plant
species particularly iir the upper I-inch layer of soil However, composite maps delineating the analvsis
of combined effects of topographic conditions, plant nutrient factors, and arsenic arid heavy meuls
concentrations in the 0 to 12 inch soil profile indicated that only approximately 50 acres confined in ihe
upper reaches of Government Gulch and some hillside slopes on the east side of Deadwood Gulch may be
restrictive to the reestablishment of plant growth
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TASK 6: CENTRAL IMPOUNDMENT AREA (CIA1 INVESTIGATION
The purpose of Task 6 was to characterize the CIA with regard to potential contaminant sources,
transport/exposure mechanisms, and seepage rates in order to evaluate possible remedial actions Pursuant
to the Work Plan, the scope of Task 6 included characterization of CIA seepage rates and seepage
pathways, characterization of the hydraulic and physical variables within each cell of the CIA, assessment
of the leachability and attenuation of various CIA materials under acid mine-water and rainfall loading
conditions, evaluation of contaminant loadings from CIA sources to the upper and lower zones of the
valley ground-water system, and characterization of surface waters in and n«**r the CIA.
Continuous core or drive samples of subsurface CIA materials were collected during installation
of monitoring wells. Chemical, geotechnical, and batch leaching analyses were conducted on the sample
materials Surface samples of CIA soils and CTP sludges were collected and analyzed for a suite ot
inorganic variables. Surface water samples from the CIA and adjacent areas were collected and analvzed
for solution condition, total dissolved metals, and major cations and anions on four occasions from
No\ember, 1987, to ie^tember, 1988 Seep*-;- •:* imaies we:*: calculated uy a v^ater budget method and
finne element model Grouna-water samples and water level neasurements w»-.e collected on a quarte.-ly
basis during 1988 and were analyzed for a suite of inorganic and organic parameters.
Task 6 project deliverables submitted to EPA included ten data reports and three technical
memoranda. The 'Revised Data Evaluation Report: Task 6.0 Central Impoundment Area'" (PD164/64110
subnitted May 21, 1990) provides a comprehensive characterization of the CIA in terms of its physical,
geo:hemicaI, and hydrological attributes
Several potential sources of contaminants were identified at the CIA during Task 6 activities
Batch leaching tests performed on gypsum core samples revealed that sulfate, arsenic, cadmium, and lead
were soluble in CIA pond water. Batch leaching test results also indicate that the flotation tailings are a
source of soluble metals However, lead was the only contaminant of concern detected in concentrations
above background levels in well GR-6T, the only well to consistently contain water in the flotation tailings
The flotation tailings were also identified as a potential source of windblown contaminant transport Jig
tail ngs underlie the entire CIA impoundment, and are considered a source of soluble metals and sulfates
as determined by batch leaching test results performed on core samples. Ground-water samples taken from
saturated jig tailings at GR-llT contained elevated levels of arsenic, cadmium, lead, zinc, dissolved solids,
fluoride, and sulfate. CIA pond water contains elevated concentrations of metals and other constituents
Water balance calculations indicate that roughly 1 cubic foot per second (cfs) of water seeps through the
CIA impoundment into the upper zone of the alluvial groundwater system.
The CIA contains various material accumulations other than slag, gypsum, and tailings The
Polishing Pond and the northwest comer of the east cell contain materials from the decommissioning of
the Smelter Complex, and CTP sludges and zinc-containing processing by-products are stockpiled in diked
areas of the east cell. All of these materials contain elevated contaminant concentrations with surface
samples from around the Polishing Pond containing the highest metals concentrations. However, no new
contaminants of concern were identified during Task 6 activities.
The following transport/exposure routes for'CIA contaminants were identified during TaiK 6
activities"
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Mining Waste NPL Site Summary Report
California Gulch
Leadville, Colorado
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-0025, Work Assignment Number 20.
A previous draft of this report was provided to Ken Wangerud of EPA
Region VIII [(303) 293-1525)], the Remedial Project Manager for the
site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
CALIFORNIA GULCH
LEADVILLE, COLORADO
INTRODUCTION
This Site Summary Report for California Gulch is one of a series of reports on mining sites on the
National Priorities List (NPL). The reports have been prepared to support EPA's mining program
activities. In general, these reports summarize types of environmental damages and associated mining
waste management practices at sites on (or proposed) for the NPL as of February 11, 1991 (56
Federal Register 5598). This summary report is based on information obtained from EPA files and
reports and on a review of the summary by the EPA Region VIII Remedial Project Manager for the
site, Ken Wangerud.
SITE OVERVIEW
The California Gulch NPL site is located in the upper Arkansas River Valley in Lake County,
Colorado. It is bounded by the Arkansas River to the west and the Mosquito Mountains to the east,
and is approximately 100 miles southwest of Denver. The study area for the remedial action
encompasses approximately 15 square miles, and includes California Gulch and the City of Leadville.
California Gulch is a tributary of the Arkansas River, with the California Gulch Drainage Basin
ranging from 10,000 to 14,000 feet above mean sea level (See Figure 1).
A Remedial Investigation conducted by EPA in 1984 indicated that the area is contaminated with
metals (including cadmium, copper, lead, and zinc migrating from numerous abandoned, and some
active, mining and minerals processing facilities). A primary source of the metals contamination in
the Arkansas River is acid-mine drainage from the Yak Tunnel into California Gulch (Reference 1,
page 4)
The Record of Decision (ROD) defines the Yak Tunnel as an Operable Unit of the California Gulch
site. Hie Yak Tunnel's discharge contributes to the contamination of California Gulch, the Arkansas
River, end the associated shallow alluvial ground-water and sediment systems. The first remedial
phase includes actions addressing the discharge of acid mine drainage containing high levels of metals
from th<; Yak Tunnel into California Gulch. This is the first Operable Unit at the California Gulch
site. Subsequent remedial activities will address public health and environmental impacts from mine
tailings and wastes, surface water in California Gulch, the ephemeral tributaries to California Gulch
and the Arkansas River, soils, slag, sediments, air, ground water, and biological media.
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California Gulch
autc
HORSE
.LEADVILL
8W-4Aa
JACKTOWN \

STRIMOTOWM
JQOO FEET
SURFACE WATER
BAUPUNO LOCATIONS
FIGURE 1. SURFACE-WATER SAMPLING STATIONS
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Mining Waste NPL Site Summary Report
The Yal: Tunnel, developed from 1895 to 1923, extends approximately 4 miles into Iron Hill, which
is located in the upper California Gulch Watershed. The Tunnel drains numerous underground mines,
and the drainage water discharges into California Gulch, which flows 4.5 miles west to the Arkansas
River.
Betweer 1859 and 1986, the area was extensively mined for gold, lead, silver, copper, zinc, and
manganese. Because of these mining operations, the Yak Tunnel was constructed (from 1895 to
1923) tc dewater mines and facilitate mineral exploration and development. From previous
investigations and sampling data, it was concluded that, as of the early 1980's, the Yak Tunnel
discharged a combined total of 210 tons per year of cadmium, lead, copper, manganese, iron, and
zinc into California Gulch, which is biologically sterile. The Arkansas River is used by the public for
recreation, and the Arkansas River is heavily used for irrigation, livestock watering, public water
supplies and fisheries. Surface-water contamination is the major impact of the Yak Tunnel discharge.
Heavy rietal migration through surface water has also caused ground-water and sediment
contami nation. Primary contaminants of concern affecting the surface water, sediments, and ground
water are cadmium, copper, lead and zinc (Reference 1, pages 1, 4, 5, 15, and 17).
In 1982 and 1983, EPA conducted a preliminary evaluation of the California Gulch site, which
consisted of an assessment of existing data and a Site Inspection In 1983, the California Gulch site
was placed on the NPL. In addition, the California Gulch site is listed under Section 304(1) of the
Water Quality Act of 1987, which requires States to identify water bodies impaired by the presence of
toxic substances, to identify point-source dischargers of these toxics, and to develop Individual
Control Strategies (ICSs) for these dischargers (Reference 1, pages 6 and 7).
EPA be, jan the Remedial Investigation of the site in 1984. The Phase I Remedial Investigation
Report, which primarily addressed surface- and ground-water contamination, was released in May
1987. In June 1987, EPA released a Feasibility Study Report and, in August, a proposed Remedial
Action Plan for the Yak Tunnel Operable Unit. A ROD describing the remedy at the site, selected in
accordance with (CERCLA), was signed by the Region VIII Administrator in March 1988. The ROD
sets forth the remedy selected for the first remedial Operable Unit at the California Gulch site. The
primary purpose of this remedy is to decrease the discharge of contaminated water from the Yak
Tunnel (Reference 1, page 6).
The selected remedial action for this site includes construction of surge ponds at the portal of Yak
Tunnel o protect the California Gulch site and the Arkansas River from accidental release of acid
water, sludge, and sediments. According to the ROD, concrete plugs will be constructed in the
tunnel to reduce migration of contaminated water and reduce the extraction of metals from raw
mineral ore. In addition, sealing shafts and drill holes, the diversion of surface water away from
3

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California Gulch
tunnel recharge areas, and the grouting of highly fractured rock will be done. A monitoring program
will be implemented to detect leaks, seeps, or migration of contaminated ground water. An interim
plant to treat ground water, which will be used to control surface seeps and migration of contaminated
surface water, will be built. The estimated capital cost of the selected remedy is $11,982,770 with
annual Operation and Maintenance (O&M) costs of $460,307 (Reference 1, Abstract).
Environmental degradation in the California Gulch area occurred from a number of mining-related
activities, including (Reference 2, pages 2-33 and 2-34):
•	Discharge to water, land, and air of mineral-processing wastes and tailings; smelter emissions
(including dust); and disposal of smelter slags.
•	Discharge to surface water of mine water from dewatering tunnels and mines.
•	Placer and hydraulic mining disturbances.
•	Construction of the Yak Tunnel to dewater mines.
•	Deforestation for fueling smelters, constructing flumes, and supplying underground mines.
Local deforestation increased runoff rates, and contributed to increased erosion and sediment
transport.
It should be noted that this NPL Site Summary Report focuses on the Yak Tunnel. This is the
Operable Unit for which Superfund activities are most advanced, and it's the only one for which
remedies have been selected (Reference 1).
OPERATING HISTORY
The Phase I Remedial Investigation study area, which includes the City of Leadville (population
3,800), encompasses an 11.5-square-mile watershed that drains along California Gulch to the
Arkansas River west of Leadville. The development of Leadville dates back to the 1850's, when the
mining of the rich mineralized zones containing principally gold, silver, lead, zinc, and copper began.
Mining, processing, and/or smelting operations in the area have been active for more than 125 years,
and varied in degree with economic demand and technological improvements. Early activities
consisted of placer mining for gold in California Gulch. Later, underground mines were developed to
the southeast of Leadville, where the ores were extracted and then processed into metallic
concentrates. These concentrates were either shipped elsewhere or further processed at the numerous
4

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Mining Waste NPL Site Summary Report
smelters in the Leadville area. Many areas received mining-related wastes, including waste rock,
tailing!., and slag piles (Reference 2, pages ii and iii).
As the mines were deepened and mining areas expanded, drainage became an economic factor in the
operational costs, particularly during periods of depressed metal prices or labor unrest, when mines
closed and flooded. Tunnels were developed to drain the ore bodies and facilitate mining. The Yak
Tunnel, which started in 1895 as an extension of the Silver Cord Tunnel, eventually reached a length
of 3.5 miles, and was the first of two major efforts to improve drainage (Reference 1, pages 4 and 6).
The Yiik Tunnel was extended several times, and has several laterals and drifts that extend into
various mine workings. The last extension was in 1923. EPA estimated that 60,000 feet of tunnels
and major laterals and 55 to 74 million cubic feet of void space are associated with the tunnel-mining
activities (Reference 1, pages 5 and 6).
By 1986, the Leadville District had produced an estimated 26,000,000 tons of ore from hundreds of
mines, whose workings comprised an extensive network of interconnected tunnels and shafts. In
1927, it was estimated that there were 75 miles of underground mine workings. By the mid-1980's,
only the Black Cloud Mine was active; it operated under a joint venture by Resurrection Mining Co
(a Newmont subsidiary) and ASARCO (American Smelting and Refining Co.). (Reference 1, pages 1
through 6).
The current condition of the Yak Tunnel is unknown, but it is suspected by EPA to be poor. The last
inspection, conducted by ASARCO in 1983, disclosed that the tunnel roof was generally weak and
had caved in at many places (Reference 1, page 6).
SITE CHARACTERIZATION
Lake County, which includes the Leadville Mining District, is located in the Colorado Mineral Belt, a
geochemically enriched zone in the central Colorado mountains. Elevations within the site range
from 9,520 to 14,000 feet above mean sea level; the low point is at the confluence of California
Gulch ,ind the Arkansas River. California Gulch cuts through glacial and glaciofluvial sediments as it
drains from the western slope of the Mosquito range to the Arkansas (Reference 2, pages 2-1 and 2-
9).
5

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California Gulch
The Remedial Investigation identified several types of mining and processing wastes, which cover
about S percent of the Remedial Investigation study area (Reference 2, page 1-6). According to EPA,
major types and locations included:
•	Five major inactive tailings impoundments. Three major tailings impoundments are located in
California Gulch between the Resurrection Mill Yard and Harrison Street: a fourth
impoundment is in Oregon Gulch; another is located west of the Town and adjacent to the
Village of Stringtown.
•	Three major slag piles. One pile is located on Harrison Street, and two piles are located near
Stringtown. Other slags occur north and west of the City. The slag residue has been spread as
road-sanding material on roadways throughout the City.
•	Over 2,000 waste dumps, varying in size from a few tons to several hundred thousand tons.
These dumps are located in upper California Gulch, Stringtown, Carbonate Hill, and Stray
Horse Gulch. Some of the piles in Stray Horse Gulch are near residential areas. Many of
these dumps contain mixed waste including tailings, waste rock, and low-grade ore, which
could not be economically processed at the time it was generated.
•	Emissions from 18 known smelters have dispersed over the area.
In addition, tunnels in the area drain ore bodies and abandoned mines. The Yak Tunnel, developed
from 1895 through 1923, extends approximately 4 miles into Iron Hill and Breece Hill, which are
southeast of Leadville. This Tunnel drains water from numerous sulfide and carbonate underground
mines. The Tunnel empties into California Gulch, which, in turn, conveys these mine waters
westward 4.S miles to the Arkansas River (Reference 2, page 1-6).
The site is extremely complex geochemically. The predominant geochemical system is an acid-sulfate
system caused by the oxidation of sulfide minerals. Acid (formed by interactions among surface
water, ground water, and sulfide minerals in ore bodies and wastes) reacts with other minerals to
release dissolved metals, including lead, copper, cadmium, iron, manganese, zinc, and iron
(Reference 2, pages vi and vii). Placer and hydraulic mining and early milling practices significantly
altered surficial materials along California Gulch. Placer and hydraulic mining mixed and reworked
alluviums and probably altered natural streambeds and floodplains (Reference 2, page
2-12).
EPA completed Phase I of a Remedial Investigation in May 1987. This included sampling and
monitoring to determine the necessity for (and the proposed extent of) remedial actions.
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Mining Waste NPL Site Summary Report
Ground Water
Mining activity has exposed mineralized ore deposits to water and oxygen. Ground-water recharge in
the area is derived primarily from precipitation and snowmelt. Water percolates into the ground and
moves hrough the alluvium and bedrock in cracks, fissures, faults, and mine workings As
oxygen ited ground water flows through the sulfide minerals, it oxidizes the pyrite minerals to form
sulfuric acid. The acid dissolves and mobilizes cadmium, copper, iron, lead, manganese, zinc, and
other metals and sulfates. The tunnel and its laterals and drifts collect this metal-laden acidic water,
and drain it to the tunnel portal. The tunnel drains into California Gulch and then to the Arkansas
River (Reference 1, page 8).
Dischaige from the Yak Tunnel is continuous, with flow ranging from 1 to 3 cubic feet per second
(cfs). The highest flows are during spring runoff when the Tunnel discharge contains the highest
metals :oncentrations resulting in poorest water quality. Sampling of Yak Tunnel discharge at the
tunnel portal through five quarterly sampling rounds during the Phase I Remedial Investigation
(September 1984 through November 1985) indicated the presence of the four metals of primary
concern. These are listed in Table 1 in ranges of concentrations in parts per billion (ppb) (Reference
1, page 8).
TABLE 1. METAL CONSTITUENTS IN YAK TUNNEL DISCHARGE
Hazardous
Range
Arithmetic
Substance
(in ppb)
Mean (in ppb)
Cadmium
195 - 520
209
Copper
731 -5,730
2,032
Lead
9-117
42
Zinc
50,100- 101,000
68,232
The arithmetic mean of the five sampling periods showed an average flow of 1.47 cfs. At this
average flow rate, the Yak Tunnel discharges 604 pounds of cadmium, 5,874 pounds of copper, 121
pounds of lead, and 197,253 pounds of zinc every year (Reference 1, page 8). The upper 25 to 50
feet of the shallow alluvial ground-water zone associated with California Gulch are also contaminated
with cadmium, zinc, other metals, and sulfates (Reference 1, page 15; Reference 2, pages ix through
xiii). Contamination is due (in part) to infiltration of California Gulch surface water (Reference 2,
page xi i). Concentrations of manganese, zinc, and cadmium exceeded Maximum Contaminant Levels
7

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California Gulch
(MCLs) in the upper 25 to 50 feet (Reference 2, pages 4-54 and 4-55). This ground water both
serves to recharge California Gulch in some stream segments and to move to deeper levels (Reference
2, pages 4-34, 4-35, and 4-37). The shallow ground water itself did not contribute directly to the
Arkansas River (Reference 2, page 4-61).
Ground water downgradient of the four tailings impoundments was also investigated in the Remedial
Investigation. Below the Oregon Gulch Impoundments, metal concentrations were among the highest
of any samples from the site (zinc 676,000 milligrams/liter (mg/1), cadmium 906 mg/1, manganese
1,396 mg/1) (Reference 2, pages 4-56 and 4-57). In general, the three Impoundments in the Gulch
itself "do not appear to significantly affect" the shallow alluvium (in general, metals were elevated but
still low compared to others) (Reference 2, pages 4-56 through 4-58). In addition, a major slag pile
on lower California Gulch was determined to contribute contaminants to shallow ground water
(Reference 2, pages 4-59 and 4-60)
Surface Water
Movement of metals through surface water in California Gulch is a major pathway of migration. In
turn, the surface water is in active interchange with the shallow ground-water system along California
Gulch (Reference 1, page 9). Both surface-water, and to a much lesser extent, ground-water
discharge to the Arkansas River. Metals precipitate in the surface-water system, and are deposited in
the sediments in California Gulch and the Arkansas River. Contaminated sediments may be scoured
continuously during high flows, and move down California Gulch and the Arkansas River. If
exposed to air, contaminated sediments in the streambed or along the banks may become windborne
and disperse through an air pathway (Reference 1, page 10).
Effluent samples collected from the Yak Tunnel were compared to EPA's Ambient Water Quality
Criteria for both acute and chronic toxicity to fresh-water aquatic life. The Yak Tunnel effluent
discharge is acutely toxic to fresh-water aquatic life, based on both high and low metal concentrations
during the five quarterly sampling periods of the Phase I Remedial Investigation. Observed
concentrations of these metals in Yak Tunnel discharge (and along the entire length of California
Gulch above the Arkansas River) exceeded acute and chronic toxicity levels for fresh-water aquatic
life. The Yak Tunnel and California Gulch waters do not support any fish because of the high metal
concentrations and turbidity (Reference 2, page 2-25). In a report, written by J.F. LaBounty, et al.,
in 1975, it was indicated that no fish and only a few limited species of aquatic invertebrates were
found in the Arkansas River for 1.5 miles downstream of the confluence with California Gulch (cited
in Reference 2, page 2-25). The Remedial Investigation also cited studies showing a "marked
decrease" in species diversity in the Arkansas River immediately below California Gulch; Brown
8

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Mining Waste NPL Site Summary Report
Trout hid bioaccumulated copper and zinc. As other tributaries enter the River, diversity rebounds
(Reference 2, page 2-26).
As part of the Phase I Remedial Investigation, EPA estimated the contribution of the Yak Tunnel to
metals loading at the point of confluence with the Arkansas River. The Yak Tunnel was estimated to
contribite an average of approximately 80 percent of the dissolved zinc and 85 percent of the
dissolved cadmium that leaves California Gulch and enters the Arkansas River annually (Reference 1,
page 15). Other sources (e.g., the shallow ground-water recharge of California Gulch) are also
recognised as contributing to the contamination of both the Arkansas River and California Gulch.
During spring runoff, the relative contribution of different sources may vary substantially.
Nevertheless, the Yak Tunnel is a major source of contamination year-round (Reference 1, page 15).
In addition to continuous flow into (and contamination of) California Gulch, the Yak Tunnel has, in
the past, released large quantities of water and sludge on occasion. This occurs when tunnel flow is
dammed or trapped by cave-ins and blockages and then breaks through and scours the tunnel floor.
In 1983, for example, a 24-hour surge released about 1,000,000 gallons (Reference 1, pages 8 and 9).
An orange plume (caused by "yellow-boy," an iron hydroxide precipitate) from released sludge was
identifiable more than 60 miles down the Arkansas River, and downstream cities that use the River
for public water had to turn off water intakes for some time (Reference 1, pages 18 and 19).
Surface water contamination is the exposure mechanism of primary concern for the Yak Tunnel
Operable Unit. Below the Yak Tunnel portal, California Gulch runs approximately 4 miles adjacent
to Leadville and through Springtown before it discharges into the Arkansas River. There is
unrestricted public access to the Gulch for most of this length. (Reference 1, page 17).
The Arkansas, in turn, is used for irrigation, livestock watering, public water supplies recreation, and
fisheries In the upper Arkansas River Valley, the primary use is recreational, with irrigation and
live-stock watering being of secondary importance (Reference 1, page 17).
ENVIRONMENTAL DAMAGES AND RISKS
The Remedial Investigation Report, completed in May 1987, concluded that cadmium, copper, lead,
and zinc are the contaminants of concern at the site. California Gulch and the City of Leadville are
in Lake County, a relatively small (380 square miles) rural area with an estimated population of
6,600. Lake County and the surrounding area is dependent upon agriculture, tourist, and mining
industries. Its past employment and economic base stemmed primarily from mining and mine-related
9

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California Gulch
industries, which have diminished significantly since 1977. Personnel at the mine have been laid off,
dramatically reducing employment in Lake County (Reference 2, page 2-29).
The Report stated that there is little specific information on wildlife within the site study area. The
wildlife found within the study area should be similar to those found in the general Leadville area.
However, the disturbed landscape and the level of past and present human activity in both Leadville
and the California Gulch area may tend to minimize the number and diversity of wildlife within the
site (Reference 2, page 2-24).
The surface-water, ground-water, and air pathways (to be addressed in a subsequent remedial action
phase) of contaminant transport may each result in exposure to hazardous substances. Plants can take
up metals from water and soils through their root systems and leaves. Aquatic organisms can absorb
metals. Domestic animals and wildlife can drink contaminated water or consume plants or other
animals that have taken up the metals. Consequently, metals can become part of the food chain and
may bioaccumulate in various organisms.
As noted above, ground-water monitoring indicated that the upper 25 to 50 feet of California Gulch
alluvial ground water are contaminated with cadmium, zinc, and other metals and pollutants (i.e.,
sulfates), which are associated with Yak Tunnel discharge. The concentrations of various metals in
ground water are in excess of both primary and secondary drinking-water standards (Reference 1,
page 15). A number of these domestic wells are in Stringtown and lower California Gulch; most
wells take water from the shallow ground-water system in the study area (Reference 2, pages 2-31
and 2-32).
Surface-water contamination is the primary concern for the Yak Tunnel Operable Unit. During the
Phase I Remedial Investigation studies, EPA identified about 35 existing wells that were drilled into
the California Gulch alluvium. Many of these wells have been abandoned because of poor water
quality. During the Remedial Investigation, EPA connected one household that used the aquifer as a
drinking-water source to the public water system (Reference 1, page 6).
Cadmium, copper, lead, and zinc are the most important contaminants in the water. Chronic
exposure to cadmium in animals and humans results in renal dysfunction, hypertension, and altered
liver and kidney function. Cadmium is also toxic to fresh-water fish in low concentrations (a few
ppb). Copper is not acutely toxic to humans. It imparts a taste to water at relatively low
concentrations (a few thousand ppb). However, it is the most toxic metal for aquatic organisms. It
interferes with reproduction and oxygen transport across the gills, and it has been reported to reduce
the ability of fish to orient themselves properly. Chronic lead exposure in relatively low
concentration in humans can cause anemia, loss of appetite, intestinal cramps, and fatigue. Higher
10

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Mining Waste NPL Site Summary Report
lead exposure can cause permanent neurological damage. The gastrointestinal absorption and
retention of lead is greater in children than in adults, so children are much more susceptible to the
adverse effects of ingestion of lead in water, food, and soil (Reference 1, pages 16 and 17). Lead
concentrations of a few hundred ppb also cause abnormalities in the Trout species. Although zinc is
an essential element in humans and is necessary for the biosynthesis of nucleic acids and polypeptides,
it can cause problems through interaction with other metals. When cadmium, copper, and zinc
concentrations occur together, synergistic effects increase their toxicity to humans and fresh-water
organisms as well (Reference 1, pages 16 through 18).
The remedy selected for the Yak Tunnel Operable Unit is designed to minimize the flow of
contaminated water out of the Yak Tunnel and prevent the uncontrolled release of tunnel effluent to
the environment (Reference 1, Declaration, page 1). Other sources and pathways of exposure will be
addressed in subsequent remedial actions
REMEDIAL ACTIONS AND COSTS
California Gulch was placed on the NPL in 1983. EPA began a Remedial Investigation of the site in
1984, and the Phase I Remedial Investigation Report, which primarily addresses surface- and ground-
water contamination, was released in May 1987. A ROD describing the remedy of the first Operable
Unit, the Yak Tunnel, was signed by the Region VIII Administrator in March 1988. The primary
purpose of the remedy is to decrease the contaminated discharge of the Yak Tunnel.
The remedy consists of:
•	Construction of surge ponds at the portal of the Yak Tunnel to protect California Gulch and the
Arkansas River from accidental releases of acidic water, sludges, or sediments from the Tunnel
due to inspections or construction
•	Construction of concrete plugs at three locations in the Tunnel to flood the sulfide zones
(flooding the sulfide zone will reduce the chemical reactions that release metals from minerals),
to halt the uncontrolled discharge of Tunnel effluent to California Gulch, and to prevent surges
•	Measures to minimize the inflow of surface water and ground water into the Yak Tunnel
system (includes sealing drill holes, shafts, and caved-in underground mine workings)
•	Implementation of a monitoring program (of surface and ground water, and inspections) to
detect any leakage, seeps, or migration of contaminated ground water
•	i mplementation of measures to prevent uncontrolled migration of contaminated water [including
grouting in the Tunnel and a water collection (pumping) system and an interim treatment plant]
11

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California Gulch
•	Contingency plans for two of the concrete plugs
*	O&M of the components of the remedy (Reference 1, Declaration, pages 1 through 5).
The estimated capital cost of the selected remedy is $11,982,770 with annual O&M costs of $460,307
(Reference 1, Abstract) EPA estimates that, to date, $2.5 million has been expended for remedial
actions.
CURRENT STATUS
The Yak Tunnel Operable Unit is in the Remedial Design/Remedial Action phase. Construction of
the treatment plant is expected to begin in the spring of 1991 and to be operational in 1992.
Subsequent Operable Units will address public health and environmental impacts from mine waste,
including tailings; surface water in California Gulch; ephemeral tributaries to the Gulch; and overall
site conditions including soils, slag, sediments, air quality, and ground water (Reference 1, page 6).
For these Operable Units, a Baseline Human Health Risk Assessment and an Environmental Risk
Assessment are expected to be completed in late 1991. A Remedial Investigation/Feasibility Study for
an Operable Unit addressing residential soils is expected to get underway in late 1991. According to
EPA Region VIII, a schedule for the remaining Operable Units at the site has not been established.
12

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Mining Waste NPL Site Summary Report
REFERENCES
1.	Supsrfund Record of Decision: California Gulch, Colorado, EPA/ROD/R08-88/020; EPA Region
VIIl; March 29, 1988.
2.	Phase I Remedial Investigation Report, California Gulch, Leadville, Colorado; EPA Region VIII;
Maj' 1987.
13

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California Gulch
BIBLIOGRAPHY
Scherer, James J. (EPA Region VIII, Regional Administrator). Record of Decision for California
Gulch Superfund Site. March 29, 1988.
Prepared for EPA Region Vm by CH2M Hill (under Contract Number 68-01-7251). Interpretive
Addenda for California Gulch Remedial Investigation, Leadville, Colorado, Volume 1 of 2.
November 1985.

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California Gulch
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From Superfund Record of Decision:
California Gulch, Colorado, EPA/ROD/R08-88/020;
EPA Region VIII; March 29, 1988

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Uriad SIMM	OMm Of	EPVROVROG-UiOM
&iwenmwnn Pr.«»caon	Emargancy and	Mwch i«a
AEPA Superfund
Record of Decision:
California Gulch, CO

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f..n H'
REPORT OOCUM.ENTATIOM
PAQS
L «PO*T NO.
EPA/ROD/R08-88/020
«. ntw mm htmn
SUPERPUND RflCORD OP DECISION
Uifornia Gulch, CO
irst Remedial Action-"
7. AutftoHU
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12.
'J.S. Environmental Protection Agency
401 N Street, S.tf.
Washington, D.C. 20460
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1S> MMM (1MB m MM
The California Gulch site is located in Lake County, Colorado, approximately
100 ai'lea southwest of Donver. The study area for this first remedial action
encompasses in 11.5 m* watershed, which includes the city of Leadville, that drains
along California Gulch to the Arkansas River. Between 1859 and 198C, the area wa«
extensively mined for gold, lead, silver, copper, zinc and manganese. Because of t.hese
ining operations, the Yak Tunnel was constructed to devater nines-and facilitate
I .ineral exploration and development. Studies indicate that the yak Tunnel discharges a
contained total of 210 tons pec year of cadmium, lead, copper, manganese, iron, and zinc
into California Gulch, which drains into the Arkansas River. Both California Gulch and
the Arkansas River are used by the public for recreation, and the Arkansas River is
heavily used for irrigation, livestock watering, public water supply and fisheries as
well. Surface water contamination is the major impact of the Yak Tunnel discharge.
Heavy met&l migration through surface water has also caused ground water and sediment
contamination. Primary contaminants of concern affecting the surface water, sediments,
and ground w.iter are cadmium, copper, lead and zinc.
(See Attached Sheet)
17. Document	a. OiiiHbMX
Record of Decision
California Gulch, CO
Pirst Remedial Action
Contaminated Media: gv, sw, sediments
qey^Cflnt^inants: Cadmium, copper, lead, zinc
COSATI M/dma
oHMMity StatMiwnt
I*. 1»curtty Ci»M (Tht» Resort)
None
21. N
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171


M. Smtrtty CUM (TM» Pwm*
None
a. *


(taMMUMia	»— mitrmmm - »wm	OmOMM. FORM Ttt <4-771

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PA/ROD/R08-88/020
California Gulch, CO
first Remedial Action
16. ABSTRACT (continued)
The selected remedial action Cor this site includes: construction of surge ponds at
the portal of Yak Tunnel to protect the California Gulch site and the Arkansas River
from accidental release of acid water, sludge, and sediments; construction of concrete
plugs at locations in the tunnel to reduce migration of contaminated water and reduce
the extraction of metals from raw mineral ore> sealing shafts and drill holea, diversion
of surface water away from tunnel recharge areas, and grouting of highly fractured rock;
implementation of a monitoring program to detect leaks, seeps or migration of
contaminated ground water* and installation of an interim treatment plant to treat
ground water, which will be pumped to control surface seeps and migration of
contaminated surface water. The estimated capital cost of the selected remedy is
$11,982,770 with annual O&M costs of $460,307.

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ifll
UMTED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VI
999 18tf! STREET - SUITE 500
DENVER. COLORADO 80202-2405
DECLARATION
FOB THE
RECORD OF DECISION
SITE NAME AND LOCATION
California Gulch
Leadville, Lake County, Colorado
Operable Unit I — Yak Tunnel
STATEMENT OF BASIS AND PURPOSE
This decision document presents the remedial action* for
Operable Unit I of the California Gulch site selected by the
Unltod States Environmental Protection Agency (EPA) in accordance
with the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (CERCLA), as amended by the Superfund
Amendments and Reauthorization Act of 1986 (SARA), and the
National Contingency Plan (NCP).
This decision is based upon the administrative record for
the Yak Tunnel operable unit of the California Gulch site. The
attached index identifies the items which comprise the
administrative record upon which the selection of the remedial
action was based.
The State of Colorado has reviewed the selected remedy.
DESCRIPTION OF THE SELECTED REMEDY
Operable Unit I addresses the discharge of acid mine
draiinage containing high levels of metals from the Yak Tunnel
into California Gulch. The hazardous substancee of primary
coricorn are cadmium, copper, leadr and zinc. The Yak Tunnel
discharge contributes to contamination of California Gulch, the
Arkansas River, and the associated shallow alluvial ground water
and sediment systems.
The selected remedy for this operable unit of the California
Gulch site is designed to minimize the flow of water out of the
Ya>; Tunnel and to prevent the uncontrolled release of tunnel
efllluent to the environment. The remedy is comprised of the
following elements.


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1.	Measures to minimize the impact of surges from the
tunnel on California Gclch and the Arkansas River.
Surg* pond« will be constructed at the portal of the Yak
Tunnel to protect California Gulch and the Arkansas River from
accidental releases of acidic water, sludges, or sediments from
the tunnel due to tunnel inspections or construction. Surge
ponds vill be constructed prior to the installation of the tunnel
plugs. Once the plugs are in place, the surge ponds vill be
incorporated into the interim water treatment system described
belov.
2.	Construction of concrete plugs at three locations within
the tunnel to flood the sulfide zones, to halt the
uncontrolled discharge of tunnel effluent to California
Gulch, and to prevent surges.
Plugs will be located in competent rock near the tunnel
portal, in the Ibex-Irene area near the middle of the tunnel, and
belov the Resurrection Nine workings near the head of the tunnel.
The plugs will serve two primary functions: source control and
management of migration, water will rise and flood the void
space behind each of the plugs. To the extent that sulfide
mineral zones exist in these areas, they vill be totally or
partially Inundated. Such inundation vill prevent or reduce the
chemical reactions which release metals from the minerals,
thereby reducing the contamination of water within the
mineralized zones. In addition, the plugs vill minimize the
migration of contaminated water to California Gulch. The plugs,
especially the lowermost one, will serve to prevent surges of
water, sludges, and sediments from the portal of the tunnel.
3.	Measures to minimize the lnflov of surface water and
ground water into the Yak Tunnel System.
These measures Include sealing shafts and drill holes,
diverting surface vater avay from tunnel recharge areas, and
grouting areas of highly fractured rock. This combination of
measures vill reduce the amount of vater entering the Yak Tunnel
system and vill thereby decrease the cost and enhance the
effectiveness of the related response actions.
4.	Implementation of a monitoring program to detect any
leakage, seeps, or migration of contaminated ground water.
Evaluation and modeling of all available geological and
hydrologlcal information indicates that rising vater levels in
the mine voids behind the plugs may result in surface seeps,
particularly in the area behind the portal plug. Also, there is
the potential for contaminated ground vater to migrate tovards
areas vhere it may have a negative impact, such as Evans Gulch or
the vicinity of the Leadville Drainage Tunnel. For these
2

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rea.-ions, a monitoring network will be constructed prior to the
installation of the tunnel plugs.
The monitoring program will consist of both field inspection
and a surface and ground water monitoring netvorJe. Periodic
fiei.d inspections will be needed to identify any surface seepage,
particularly in the vicinity of the portal plug. The ground
vattir monitoring netvorJe will consist of a series of monitoring
veils and/or shafts to measure vater levels and vater quality.
The number and location of monitoring points associated vith each
pluqr vill depend on the geologic and hydrologle conditions
associated vith each. The monitoring points vill be used to
identify baseline information on ground vater levels and quality,
against which changes in water levels and quality can be
measured. The surface vater monitoring netvork will be used to
monitor changes in both quality or flov as a result of the
remedy. Surface monitoring stations vill be in California Gulch
and Evans Gulch. Both the field inspections and the periodic
vater measurements vill be used to predict, identify, and track
any surface vater seeps or changes in ground vater flov and
quality.
5. Measures to prevent uncontrolled migration of
contamlnatad vater.
Because rising vater levels pose a risk of seepage and
migration of contaminated vater, the selected remedy incorporates
measure* to mitigate this risk. Grouting of potential leakage
points, such as fracture zones, caved-in areas, and drill holes,
vill be done. To control ground vater levels, and thereby
control surface seeps and migration of contaminated vater, a
system to lover vater levels vill be installed behind the portal
plug. As necessary, vater vill be pumped from behind the portal
plug and routed to an interim treatment plant near the portal of
the runnel. Tho plant vill use available technologies to settle
out isetals and then release the vater to California Gulch. The
surgu ponds described above vill become part of this treatment
systum. Sludge vill be retained In the ponds vhile the interim
treatment system is operating. As part of a subsequent operable
unit,, a comprehensive treatment system vill be developed and
integrated into a permanent site remedy.
The selected remedy also includes contingency plans for the
Ibex-Irene and Resurrection plugs. Because the probability of
surface seepage caused by these plugs is small, at the outset
only monitoring is necessary. If, hovever, monitoring Indicates
that adverse impacts may occur, a pump and treat system, similar
to the one installed for the portal plug, vill be installed and
operaitod.
3

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6. Operations and maintenance of the selected remedy.
Routine operations and maintenance of the installed
facilities will be required. This includes the surge ponds, the
water control measures, the monitoring systems, and the water
collection and interim treatment plant.
These elements comprise the first remedial operable unit at
the California Gulch site. Subsequent operable units will
address public health and environmental impacts froa mine
tailings and wastes, surface water in California Gulch, the
ephemeral tributaries to California Gulch, and the Arkansas
River, soils, slag, sediments, air, ground water, and biological
media.
DECLARATIONS
Pursuant to CERCLA, as amended by SARA, and the NCP, I have
determined that the selected remedy for Operable Unit Z at the
California Gulch site is protective of human health and ^he
environment, attains all location-specific and action-specific
Federal and State requirements that are applicable or relevant
and appropriate (ARARs) to this remedial action, and is cost-
effective.	*
The-remedy-is-not expected to attain- all th« chemical-
specific requirements. Because ol th»-contribution of other
sourcee to surface, water contamination, the- remedy is not
expected to attain the degree of cleanup of surface water set by
these chemical-specific requirements- Therefore, I have found
that a waiver 1s necessary under Section 121(d)(4)(A) of SARA. A
waiver is appropriate if the remedial action selected is only
part of a total remedial action that will attain a level or
standard of control at least equivalent to the legally applicable
or relevant and appropriate standard, requirement, criteria, or
limitation. The treataent facility component of the selected
remedy la an interim action designed to decrease the release and
threatened release of metals from the Yak Tunnel. It is only a
first step toward cleanup of California Gulch surface water and
is part of a total remedial action for the site. Response
actions in subsequent operable units, in combination with this
selected remedy, will attain a level or standard of control at
least equivalent to ARARs.
The remedy satisfies the statutory preference for remedies
that employ treatment that reduces toxicity, mobility, or volume
as a principal element and utilizes permanent solutions and
alternative treatment technologies to the maximum extent
practicable.
4

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Because this remedy will result in hazardous substances
remaining on site above health-based levels, reviews of the
remedial action will be conducted no less often than each S years
after the initiation of the remedial action to assure that human
health and the environment are being protected by the remedial
action being implemented.
Regional Administrator
Region VIII, U.S. Environmental
Protection Agency
5

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CONTENTS
Page
I.	Site Name, Location, and Description	l
II.	Site Status	1
Site History	1
Response History	6
Enforcement History	6
III.	Site Characteristics	7
Source of Contamination	7
Pathways of Migration	9
Public Health and Environmental Impacts	16
iv. Community Relations History	18
V.	Alternatives Evaluation	20
Development of Alternatives	21
Description of Alternatives	22
Initial Screening	24
Detailed Description of Remaining
Alternatives	26
Detailed Analysis of Alternatives'	30
VI.	Selected Remedy	34
Description of Selected Remedy	3 5
Cost of Selected Remedy	48
Statutory Determinations	4 9
Schedule	56
References	S8
Appendix A. Hydrogeologic Impact of Selected Remedy
Appendix B. Cost Estimates
Appendix C. Evaluation of Applicable or Relevant and
Appropriate Requirements
Appendix D. Statement of findings Concerning
Floodplains and Wetlands
i

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TABLES
Pace
1	Comparison of Metals Concentrations in Yak
Tunnel Discharge to Ambient Water Quality
Criteria	11
2	Comparison of Metals Concentrations Ranges
at Six Locations Along the Mainstem of
California Gulch to Ambient water Quality
Criteria	13
3	Comparison of Metals Concentrations on the
Arkansas River to Ambient Hater Quality
Criteria	14
4	Comparison of Alternatives	31
5	Monitoring Program	4 3
S Potential Adverse Short-Term Impacts Associated
with the Selected Remedy	51
*' Potential Adverse Long-Term Impacts Associated
with the Selected Remedy	5 2
FIGURES
1	Location Map	2
2	Location—Yak Tunnel and Major Laterals	3
3	Potentially Contaminated Media	10
4	Surface Water Sampling Location*	12
5	Schematic Showing Selected Remedy for the
Yak Tunnel	37
6	Monitoring Plan Map	42
ii

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I. SITS NAME, LOCATION, AND DESCRIPTION
The California Gulch site is in Lake County, Colorado,
approximately 100 miles southwest of Denver (Figure 1). The
Phase I Remedial Investigation (RI) study area, which
includes the City of Leadville (population 3,800),
encompasses an 11.5-square-mile watershed that drains along
California Gulch to the Arkansas River wast of Leadville.
The California Gulch drainage basin ranges from 10,000 to
14,0d0 feet above mean sea level (mal) in elevation (EPA,
1987a).
The RI conducted by the U.S. Environmental Protection Agency
(EPA) indicates that the area is contaminated with metals
including cadmium, copper, lead, and zinc emanating from
numerous abandoned and some active mining and minerals
processing facilities. A primary source of the metals
contamination is acid mine drainage from the Yak Tunnel into
California Gulch.
-The Yak Tunnel (Figure 2) extends underground approximately
3-1/2 to 4 miles into Iron Hill and Breece Hill. The tunnel
collects ground water from numerous underground mines and
then discharges flow into California Gulch.
Based on the annual average flow rate and annual average
dissolved concentrations, the Yak Tunnel discharges a
combined total of 210 tons per year of cadmium, copper,
iron, lead, manganese, and zinc; into California Gulch (EPA,
1987a).
'This Record of Decision (ROO) addresses the Yak Tunnel as an
"operable unit" of the California Gulch site. Under the
National Contingency Plan (NCP), an operable unit is "a
-discrete part of the entire response action that decreases a
release, threat of relet**/ or pathway of exposure" (40 CFR
S 300.68(c)).	units will address mine
wastes, ephemeral surface water, ground water, soils, and
other environmental media.
II. SITE STATUS
SITE HISTORY
Mining activities in Leadville began in 1859 when
gold-bearing placer deposits were found along California
Gulch. Since that time, mining activity has almost been
continuous, although there have been production cessations
or slowdowns because of economic conditions or labor issues.
An estimated 26 million tons of ore were produced in the
Leadville Mining District from 1859 through 1966 (ASARCO,
1987).
1

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In its comments on the Yak Tunnel Feasibility Study (FS)
(ASARCO, 198?) , ASARCO Incorporated provided the followina
history o~f the Leadville Mining District:
Leadvill» began as a gold camp in 1861 when prospectors
working the channels of Arkansas River tributaries
found gold-bearing placer deposits in California Gulch,
east of the present town. The placers were not
extensive and production declined rapidly. Some small
gold-bearing lode veins discovered along the gulch
helped to keep the caap from dying out completely after
1868. In 1874, two men, curious about the "heavy sand"
that interfered with the recovery of gold in the placer
sluice boxes, investigated the composition of the
material. It proved to be silver-bearing lead
carbonate. Examination of outcrops on nearby hillsides
disclosed the source of the mineral, and Leadville's
importance as a mining district dates from this
discovery.
As the search for ore became widespread, extensive
replacement deposits of lead and silver and, later on,
rich gold ores associated with fissure veins were
found. Copper, usually associated with the gold%ore,
assumed minor importance. Zinc and manganese minerals
occurred with the lead-silver ores; they were of little
value in the early days, but were later mined
extensively.
As the mines were deepened and mining areas expanded,
drainage became an economic factor in the operational
costs, particularly during periods of depressed metal
prices or labor unrest. The Yak Tunnel, which started
in 1895 as an extension of the Silver Cord Tunnel,
eventually reached a length of 3-1/2 miles and was the
first of two major efforts to improve drainage. The
second major effort, the Leadville Drainage Tunnel, was
started in 1943 and was finally completed as far as the
new Mikado shaft near Stray Horse Gulch in 1952	
Depresoions occurred in 1893, 1907, and 1930-34. Labor
trouble occurred in 1896, 1897, and 1919. During these
tinea, the majority of the mines in the Leadville
District were closed and flooded. Mining also was
curtailed by low metal prices and by depletion of ore
reserves, which were not maintained in advance of
mining; therefore, economic production levels could not
be maintained.
with the advent of World War II, operating properties
in the district increased production as a result of the
federal support-premium price paid for copper, lead,
and zinc. During the war, the major portion of the
4

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recorded production came from processing old dumps by
the Ore and Chemical Company and John Hamm Milling
Company; however, production increases were recorded
from the Resurrection No. 2, Fortune, Eclipse, and
Hellena shafts, as well. Ore output practically ceased
after 1957 when the Irene shaft was closed due to low
metal prices.
In 1965, a joint venture between ASARCO Incorporated
and Resurrection Mining Company reopened the Irene
workings and substantial ore reserves were proven in
the down-dropped block in the eastern portion of the
Leadville district bordered by the Ball Mountain,
Weston, and Garbutt faults. In 1969, a new shaft, the
Black Cloud, was sunk in Iowa Gulch to access the newly
found ore reserves. The Black Cloud mine and mill went
into production in April 1971 and has operated
continuously since that time. The other significant
mine to operate in the district since the Resurrection
Mill shut down in 1957, is the Sherman Mine at the head
of Iowa Gulch. This mine, now owned by the Leadville
Corporation, was operated by Day Mines and the Heela
Mining Company between 1976 and 1984, after which it
was shut down for economic reasons.
There are currently a few active, moderate-sized mining and
reprocessing operations in the Leadville area. However,
since mining activities began in Leadville, hundreds of
miftes, numerous mills, more than 40 smelters, and several
placer operations have contributed to both the past economy
and current environmental conditions in Leadville.
Emmons et al. (1927) identified 1,329 mine shafts, 155
tunnels, and 1,628 prospect holes in the Leadville Mining
District, which have an estimated aggregate length of
75 miles. In the surrounding area, Behre (1953) identified
an additional 1,800 openings of various types. These
workings comprise an extensive network of connected tunnels
and shafts.
The Yak Tunnel was constructed to dewater mines and to
facilitate mineral exploration and development. The tunnel,
driven in 1895 to drain the Iron Hill mines, was extended
several times. The last extension was in 1923.
The tunnel now has several major laterals and drifts that
extend from the tunnel into the various mine workings.
ASARCO (1987) reports some of the connections off the tunnel
as follows: the Horseshoe, the Rubie, the North Mike, the
South Mike, the Ibex No. 4, the Little Winnie, the
Resurrection No. 1, the Fortune, the Resurrection No. 2, and
the Dolly B. In addition, there are six working winzes:
the White Cap, the Cord, the Mike, the Willard, the My Day,
5

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«md the Diamond. f.PA estimated that 60,000 f«»et of tunnels
and ma^or laterals and 55 to 74 million cubic feet cf void
space are-associated with the tunnel mining activities (EPA,
1987b).
The current physical condition of the Yak Tunnel is unknown
hut is suspected to be poor. The last inspection, conducted
hy ASARCO in 1993, disclosed that the tunnel roof was
generally weak and had caved in at many places.
RESPONSE HISTORY
In 1982 and 1983, EPA conducted a preliminary evaluation of
the California Gulch site, which consisted of an assessment
of existing data and a site inspection. In 1983, the
California Gulch site was placed on the National Priorities
List of sites which are the highest priority for EPA
response action.
EPA began the RI of the site in 1984. The Phase I RI
report, which primarily addresses surface and ground water
contamination, was released in May 1987. During the RI, EPA
determined that response actions for the site could be
separated into operable units to facilitate site
remediation. EPA conducted a removal operable unit to
connect a household to the public water system. EPA also
developed a remedial operable unit to decrease the release
and threatened release of hazardous substances, pollutants,
and contaminants from the Yak Tunnel.
In June 1987, EPA released a PS report and, in August, a
proposed remedial action plan for the Yak Tunnel operable
unit. EPA held a 90-day public comment period and a public
meeting to provide opportunity for public review and comment
on the FS report and proposed remedial action plan.
This ROD sets forth the remedy selected for the first
rtimadial operable unit at the California Gulch site. The
primary purpose of this remedy is to decrease the discharge
oil contaminated water from the Yak Tunnel. Subsequent
operable unit studies are planned to address mine wastes and
ephemeral surface flow, and overall site conditions
including soils, slag, sediments, air quality, surface
wuter, and ground water.
ENFORCEMENT HISTORY
Irt 1982 and 1983, EPA Identified seven parties as potentially
responsible for California Gulch site contamination based on
their ownership or operation of mining or minerals
pz'ocessing facilities at the site.
6

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In the spring and summer of 198 3, EPA sent notice letters to
Apache Energy and Minerals Company, ASARCO, C and H
Development Corporation, Hecla Mining Company, Robert Elder,
Resurrection Mining Company, and Rock Hill Mines Company.
In the letters, EPA notified the parties that they were
considered potentially responsible for the release of
hazardous substances, pollutants, and contaminants at the
site, and offered each party an opportunity to participate
voluntarily in a response action. EPA enclosed with each
letter a copy of a draft work plan for the RI/PS. None of
the potentially responsible parties agreed to prepare the
RI/FS or undertake response actions at the site. Therefore,
EPA performed the Phase I RI and the Yak Tunnel FS using
Superfund money.
In spring 1996, EPA identified and sent notice letters to
six additional potentially responsible parties: Atlas
Mortgage Company; Oenver and Rio Grande Western Railroad
Company; Leadville Corporation; Leadville Silver and Gold,
Inc.; Newmont Mining Corporation; and the Res-ASARCO Joint
Venture. Again, these parties were identified based on
their ownership and operation of mining and minerals
^rqcessing facilities at the site.
In August 1986, the United States filed an action against
these 13 parties in the United States District Court for the
District of Colorado: United States v. Apache Energy and
Minerals Co.. No. 86-C-1675 (D. Colo, filed Aug- 6, 1986).
In this action, the United States seeks to obtain a cleanup
for the site and recovery of past and future response costs.
In February of 1987, this case was consolidated with a
related State case titled Colorado v. ASARCO. Inc..
No. 83-C-2388 (D. Colo, filed Dec. 9, 1983).
The United States will seek to have responsible parties
implement the Yak Tunnel remedy. Two of the defendants have
proposed to conduct remedies for the tunnel. These
remedies, which were evaluated by EPA during the remedy
selection process, are discussed in the "Alternatives
Evaluation" section of this ROD.
III. SITE CHARACTERISTICS
This section summarizes the nature and extent of the release
and pathways of exposure to hazardous substances,
pollutants, and contaminants discharged from the Yak Tunnel.
SOURCE OF CONTAMINATION
The Yak Tunnel and its laterals extend through sulfide and
carbonate ore bodies under Iron Hill, Breece Hill, upper
California Gulch, and upper Evans Gulch as shown previously
7

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(Figure 2). The suite of minerals that constitutes the ore
bodies drained by the Yak Tunnel is a complex assemblage
including native copper, gold, and silver; and sulfides,
carbonates, and silicates of these and other metals (EPA,
1987b) The primary minerals are predominately sulfides of
iron, lead,- and zinc. As discussed in the "Site History"
subsection of this ROD, these ore bodies have been
extensively mined.
This mining activity has exposed mineralized ore deposits to
water and oxygen. Ground water in this area it derived
primarily from precipitation and snowmelt. Hater percolates
into the ground and moves through the alluvium and bedrock
in cracks, fissures, faults, and mine workings. Aa
oxygenated ground water flows through the sulfide minerals,
it oxidizes the pyrite minerals to form sulfuric acid. The
acid dissolves and mobilizes cadmium, copper, iron, lead,
manganese, zinc, and other metals and sulfates. Tha tunnel
and its laterals collect this metal-laden acidic water and
drain it to the tunnel portal.
Discharge from the Yak Tunnel is continuous with flow
ranging from 1 to 3 cubic feet per second (cfs). The
highest flows are during spring runoff when the tunnel*
discharge contains the highest metals concentrations
resulting in the poorest water quality. Sampling of Yak
Tunnel discharge at the tunnel portal through five quarterly
sampling rounds during the Phase I RI indicated the presence
of hazardous substances (metals) in the following ranges of
concentrations in parts per billion:
Arithmetic
Hazardous Range	Mean
Substance		(ppb)	(ppb)
Cadmium	195-520	209
Copper	731-5,730	2,032
Lead	9-117	42
Zinc	50,100-101,000	63,232
The arithmetic maan of the five sampling periods indicates
an average flow of 1.47 cfs. At this average flow rate, the
Yak Tunaal discharges 604 pounds of cadmium, 5,874 pounds of
copperr 121 pounds of lead, and 197,253 pounds of zinc into
£h« environment every year.
In addition to this continuous discharge of hazardous
substances, the Yak Tunnel is subject to "surges" or sudden
releases of large quantities of water and sludge (EPA,
1987a). Due primarily to lack of maintenance, the tunnel is
deteriorating, and there are cave-ins and blockages in the
tunnel or the laterals. The tunnel flow can becom* dammed
or trapped behind the blockages. Hater then builds up
behind the blockage and eventually breaks through, scouring
8

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the buildup of metal-laden sludge from the tunnel floor.
Water and—sludge are then discharged through the tunnel
portal. A surge occurred in 1985 that lasted approximately
2 4 hours and released an estimated 1 million gallons of
contaminated water at an instantaneous peak flow rate of
10 cfs measured at the portal (EPA, 1987a).
PATHWAYS OF MIGRATION
After passing through the tunnel portal, metals from the Yak
Tunnel can move through various environmental media.
Figure 3 shows a conceptual model of the potentially
contaminated media and the pathways of contaminant migration
at the site.
Movement of metals through surface water in California Gulch
is a major pathway of migration. In turn, the surface water
is in active interchange with the shallow ground water
system along California Gulch (EPA, 1987a). Both surface
water and, to a much lesser extent, ground water discharge
to the Arkansas River surface water. [[Metals precipitate in
the surface water system and become a part of the sediments
in California Gulch and the Arkansas River. Contaminated
sediments may be scoured continuously during high flows and
move down California Gulch and the Arkansas River. If
exposed to air, contaminated sediments in the stream bed or
along the banks may become wind-borne and dispersed through
an air pathway/^
Surface water contamination is the ma?or impact of the Yak
Tunnel discharge. Table 1 compares metals concentrations in
the Yak Tunnel effluent with EPA's ambient water quality
criteria for acute and chronic toxicity to freshwater
aquatic life (EPA, 1987a).*
In developing the ambient water quality criteria, EPA
determined that the acid soluble test method would be the
appropriate method for certain metals. Since there
currently is no EPA-approved acid soluble test method, EPA
recommends applying the ambient water quality criteria
using the "total" recoverable method (see EPA, Quality
Criteria for Water 1986, May 1986). During the Phase I RI,
EPA used both the dissolved and total metals methods to
analyze metals concentrations In surface water (see Phase I
RI Report Appendices). In this ROD, all water quality data
are reported as total metals. The total metals method best
represents the potential toxicity in the surface water
chemistry of California Gulch. The use of total metals
concentrations may be overly protective in the Arkansas
River because of the different chemical environment.
9

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POINT SOURCE FLOWS TO
CALIFORNIA QULCH
Yak Tunnol
9awaflo Troatmont
Plant Outfall
AIR
GROUND WATIR
SYSTEMS
CALIFORNIA QULCH
8URFACI WATIR SYSTEM
SURFACE SOLIOS
•lags
mlae. mlno spoils
soils
Ludfllk Storm Drain
Uppor Quloh
Ortfon Quleft
Starr Dlteli
FIGURE 3
POTENTIALLY CONTAMINATED MEDIA AND PATHWAYS
10

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Table 1
COMPARISON OF METALS CONCENTRATIONS IN YAK TUNNEL
DISCHARGE TO AMBIENT WATER QUALITY CRITERIA
Metal
Cadmium
Copper
Lead
Zinc
Ambient Water h
Quality Criteria '
Acute	Chronic
Concentrations
(ppb)	
3.9
18
82
120
1.1
12
3.2
110
Range Detected in the
Yak Tunnel Effluent
195-520
731-5,730
9-117
50 ,100-101,000
See Appendix C of this ROD for detailed discussion of
.Ambient Water Quality Criteria.
Values assume hardness of 100 rng/1 CaCO^.
Source: EPA, 1987a.
Table 1 shows that the Yak Tunnel discharge would be acutely
toxic to freshwater aquatic life, based on both high and low
met*al concentrations during the five quarterly sampling
periods of the Phase I RI. In addition, the observed
concentrations of these metals in Yak Tunnel discharge were
many times the chronic toxicity levels for freshwater
aquatic life. For zinc, the highest concentration in the
Yak Tunnel effluent was more than 900 times the chronic
toxicity level for freshwater aquatic life.
The Yak Tunnel is the major contributor to contamination of
California Gulch surface water. Above the Yak Tunnel,
California Gulch flows intermittently during spring runoff
and heavy rainstorms. Throughout much of the year, the Yak
Tunnel is the primary source of continuous flow for
California Gulch below the tunnel. Another source of
continuous flow is the Leadville sewage treatment plant,
which discharges treated effluent to lower California Gulch
below Stringtown.
During the Phase I RI, EPA periodically analyzed surface
water samples from six locations (SW-3A, SW-4, SW-4A, SW-7,
SW-9, and SW-12) along the length of the California Gulch
mainstream below the Yak Tunnel (Figure 4). This segment of
California Gulch, which is approximately 4 miles long, runs
adjacent to Leadville and through Stringtown before it
discharges into the Arkansas River.
11

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5W-I3
HOR8E



CALlfOMtlA
CALIEORNI
4000 FEET
SURFACE WATER
8AMPLINQ LOCATIONS
FIGURE 4
SURFACE WATER 8AMPLIHO 8TATION8

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Table 2 shows the range of metal concentrations at various
sampling"locations for four metals of concern detected in
California Gulch surface water. For these metals, the acute
and chronic toxicity levels for freshwater aquatic life were
exceeded along the entire length of California Gulch below
the Yak Tunnel. At times, the observed contamination levels
ranged from hundreds to thousands of times greater than the
criteria value.
Table 2
COMPARISON OF RANGES OF METALS CONCENTRATIONS WITH AMBIENT
WATER QUALITY CRITERIA AT SIX LOCATIONS ALONG THE
MAINSTREAM OF CALIFORNIA GULCH
Criteria and
Sampling
Locations
Ambient Water
Quality
Criteria
Cadmium CoppeT
Concentrations
(ppb)
Lead
TT
nc
Acute
3.9
18
82
Chronic
1.1
12
3.2
Location



SW-3A
56-390
254-4,280
9.5-239
SW-4
178-395
810-3,980
32-270
SW-4A
200-285
778-1,390
52-55
SW-7
82-382
174-3,620
105-3,500
SW-9
105-384
441-3,470
146-4,740
SW-12
62-290
26-2,560
16-2,860
120
110
3,060-75,000
50,390-75,900
6,440-56,100
27,310-76,600
27,000-77,300
20,170-57,800
*Values assume hardness of 100 mg/1 CaCOj.
Source: EPA, 1987a.
California Gulch contributes to contamination of surface
water in the Arkansas River. In the Phase I RI, sampling
points were located both above and below the confluence of
California Gulch with the Arkansas River (Figure 4). Data
from these locations demonstrate the impact of California
Gulch on Arkansas River water quality (Table 3).
It should be noted that during the five sampling rounds,
lead and cadmium were not detected in the Arkansas River
upstream of the confluence with California Gulch. Below the
13

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Table 3
COMPARISON OF METALS CONCENTRATIONS IN THE
ARKANSAS RIVER WITH AMBIENT WATER QUALITY CRITERIA
Metal
Cadmium
Ambient Water
Quality Criteria
Concentrations
	(ppb)
Acute Chronic
3.9
1.1
Copper 18
12
Lead
82
3.2
::inc
120
110
Arkansas River
Concentrations
Sample
Above
Below
Date
Confluence
Confluence
11/84
BDLb
BDL
3/8S
BDL
23
6/85
BDL
BDL
9/85
BDL
5.8
11/85
BDL
5.7
11/84
12
BDL
3/85
3.8
189
6/85
4
29
9/85
4.6
37
11/85
6
24
11/84
BDL
BDL
3/85
BDL
439
6/85
BDL
25
9/85
BDL
6.8
11/85
BDL
9.7
11/84
331
1,625
3/85
637
5,630
6/85
132
709
9/85
353
2,060
11/85
391
1,870
^Values assume hardness off 100 mg/1 CaCO,.
BDL « below detection limit.
Sources EPA, 1987a.
confluence, the acute and chronic criteria were exceeded
during threo of the five sampling rounds for cadmium.
Concentrations of lead exceeded the chronic criteria for
four out of five sampling rounds and exceeded the acute
criteria for one of the sampling rounds. The concentrations
of copper also exceeded both the acute and chronic criteria
bulow the confluence in four of the five sampling rounds.
Upstream from the confluence, the zinc levels were already
14

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relatively high: however, they increased more than five
times in concentration below the confluence with California
Gulch and exceeded both acute and chronic criteria.
As part of the Phase I RI, EPA estimated the contribution of
the Yale Tunnel to metals loading at the point of confluence
with the Arkansas River. The Yak Tunnel was estimated to
contribute an average of approximately 80 percent of the
dissolved zinc and 85 percent of the dissolved cadmium that
leaves California Gulch and enters the Arkansas River
annually (EPA, 1987a). Other sources are also recognized as
contributing to the contamination of both the Arkansas River
and California Gulch (EPA, 1987a). During spring runoff,
the relative contribution of different sources may vary
substantially. Nevertheless, the Yak Tunnel is a ma3or
source of contamination year-round.
In addition, metals in the Yak Tunnel discharge contribute
to contamination of the shallow alluvial ground water zone
associated with California Gulch. The Phase I RI indicated
that there is an interchange between California Gulch
surface water and the shallow alluvial ground water zone
b»iow p»ndry FquGround water monitoring indicated
that the upper 2Sto50 feet of California Gulch alluvial
ground water are contaminated with cadmium, zinc, and other
metals and pollutants such as sulfates, which are associated
with Yak Tunnel discharge. The concentrations of various
metals in ground water are in excess of both primary and
secondary drinking water standards (EPA, 1987a).
As illustrated in the conceptual model (Figure 3), metals
from the Yak Tunnel also contribute to contamination of the
stream sediment system. Metals in solution can become
separated from the solution, forming precipitates that become
part of the stream sediment system. These precipitates can
remain suspended or settle out of the water. Yellow boy is
an iron hydroxide precipitate and is a visual example of
this process, which can be seen throughout the length of
lower California Gulch. The sediment system's dynamic
character is demonstrated at high flows when the sediments
and precipitates are picked up from the stream bed and are
jiloved further downstream.
If sediments dry out because of reduced streamflow or
movement of the stream channel, contaminated materials can
become wind-borne. Hence, metals from Yak Tunnel can become
more widely dispersed than simply through water transport.
The air pathway will be addressed in a subsequent operable
unit.
15

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PUBLIC HEALTH AND
SNVIP0NMEN7AL IMPACTS
The surface water, ground water, and air pathways of
contaminant transport may each result in exposure of living
organisms to hazardous substances. Plants can take up metals
from water and soils through their root systems and leaves.
Aquatic organisms can absorb metals. Domestic animals and
wildlife can drink contaminated water or consume plants or
other animals that have taken up metals. Humans can be
exposed through inhalation or ingestion of contaminated
water, sediments, and food. Consequently, metals can become
part of the food chain and may bioaccumulate in various
organisms.
Cadmium, copper, lead, and zinc are key metals of concern.
T:!te following are brief summaries of the toxic effects of
tiese metals:
o Cadmium—Chronic exposure to cadmium in animals
and humans results in renal dysfunction,
hypertension, and altered liver and kidney
function. Cadmium is toxic to freshwater fish in
low concentrations (a few ppb). Cadmium
interferes with normal osmoregulation, liver and
kidney enzymatic activities, and maturation of
reproductive organs. Trout species are sensitive
to cadmium and juvenile fish are commonly more
sensitive than either eqga or adults, when
cadmium, copper, and zinc concentrations occur
together, synergistic effecta increase their
toxicity to freshwater organisms.
o Copper—Copper is not acutely toxic to humans, it
imparts a taste to water at relatively low
concentrations (a few thousand ppb), which could
deter use of contaminated water. Copper is one of
the most toxic metals for aquatic organisms.
Chronic exposure to copper in concentrations
greater than 12 ppb reduces growth and rate of
reproduction, may interfere with oxygen transport
across gill membranes, and has been reported to
reduce the ability of fish to orient themselves
properly.
o Lead—Chronic exposure to relatively low
quantities of lead in humans can cause anemia,
loss of appetite, intestinal cramps, and fatigue.
Lead can bioaccumulate in humans, and exposure to
higher lead levels can cause permanent
neurological damage. The gastrointestinal
absorption and retention of lead is greater in
children than in adults, so children are much more
16

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susceptible to the adverse effects of ingestion of
lead in water, food, and dirt. Chronic exposure
to lead concentrations of 13 ppb in rainbow trout
causes reduced hemoglobin production and changes
in red blood cells. Lead concentrations of a few
hundred ppb causes spinal deformities in brook
trout. Fish that are exposed to chronic and
subchronic levels of lead generally show changes
in their tissue structure. Fish eggs and
juveniles may be more sensitive to lead, and
several other metals, than the adults.
o Zinc—Zinc is an essential element in humans and
is necessary for the bioaynthesis of nucleic acids
and polypeptides. Zinc is rarely toxic to humans,
but its synergistic/antagonistic interaction with
other metals may cause problems. Susceptibility
of fish to zinc is largely species-dependent.
Rainbow trout and brook trout are fairly
susceptible to chronic zinc exposure. Juvenile
rainbow trout are about three times more resistant
than eggs. Water temperature and hardness
significantly influence the toxicity of zinc.
Zinc toxicity causes decreased growth, kidney
dysfunction, gill damage, and alterations in
behavior.
Surface water contamination i* the exposure mechanism of
primary concern for the Yak Tunnel operable unit. Below the
Yak Tunnel portal, California Gulch runs approximately
4 miles next to Leadville and through Stringtown before it
discharges into the Arkansas River (Figure 4). There is
unrestricted public access to the gulch for most of this
length. Children and adolescents are attracted to water for
exploration and recreation. Both children and adults may
make other recreational use of the stream. Through such
activities, people would be exposed to metals through
inadvertent ingestion of contaminated material.
The Arkansas River is heavily used for irrigation, livestock
watering, public water supply, recreation, and fisheries.
In the upper Arkansas River Valley, the primary uses of the
Arkansas River are recreational and, secondarily, irrigation
and stock watering.
Further downstream, water from the Arkansas River is
diverted for municipal water supplies. Flow has been
diverted from the Arkansas River below Granite, Colorado, to
serve the cities of Aurora and Colorado Springs. Surge
events that mobilize sludges from the Yak Tunnel have
affected Arkansas River water use. In 1983, during an
inspection of the Yak Tunnel, ASARCO personnel released
sludge or "yellow boy" that had formed behind debris dams.
17

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The release turned a 20-mile stretch of the Arkansas River
orange for several days and forced downstream cities,
including Colorado Springs, Canon City, and Florence, to
turn off their water intakes for 5 days. After a surge in
1985, an orange plume, which eventually dissipated in the
Fueblo Reservoir, was seen more than 60 miles downstream.
Again, downstream water intakes were shut down.
The State of Colorado has designated segments of the
Arkansas River, including the stretch from the confluence
with California Gulch to Lake Fork, for various uses,
including Class 1 cold water aquatic life. This
classification covers waters that, based on water quality
levels, flow, and stream bed characteristics, could provide
a habitat that protects a wide variety of cold water biota
such as trout and other sensitive species.
However, biological studies indicate that habitat
degradation from metals contamination has reduced the
capacity of this segment of the Arkansas River to support
WBll-balancod aquatic populations. Below the California
Gulch confluence, both the quantity and variety of fish and
microinvertebrate populations are reduced (Roline et al.,
1)81). Evidonce also suggests bioaccumulation of metals and
negative impacts on the reproductive capacity of trout
(laoline et al., 1981; La Bounty et al., 1975).
There is also the potential for the exposure of humans to
mutals through ground water. The previously mentioned
shallow alluvial ground water zone was used as a source of
dmaestic water. During the Phase I RZ studies, EPA
identified 33 existing wells that were drilled into the
California Gulch alluvium. Many of these wells have been
abandoned because of poor water quality. In 1986, EPA
connected the one remaining household that used the aquifer
a:i a drinking water source to the public water system.
However, at this time, no steps have been taken to prevent
puople from using their existing wells or from drilling new
wulls into the contaminated alluvium.
An shown in Figure 3, there are multiple sources and
pathways of metals contamination in the Leadville area. The
rumody selected for the Yak Tunnel operable unit is designed
tci address a major source of contamination and to reduce
significantly the amount of metals released into the
environment. Other sources and pathways of exposure will be
addressed in subsequent operable units.
IV. COMMUNITY RELATIONS HISTORY
From the beginning of the RI/FS process for the California
Gulch site, EPA has conducted community relations
18

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activities and sought the involvement of potentially
responsible parties. These activities have included
correspondence with potentially responsible parties and
members of the public, preparation of press releases and
fact sheets, and periodic meetings with elected officials,
potentially responsible parties, and the community to
discuss the Superfund process and the status of site
activities.
On July 7, 1987, EPA issued a press release announcing the
availability of the Yak Tunnel FS report. In July 1987, EPA
distributed a fact sheet describing the alternatives
evaluated to more than 100 people on EPA's mailing list and
notified the public of the opportunity to comment. EPA
placed copies of the FS report in the Lake County Library in
Leadville and in the EPA Region VIII library in Denver. EPA
also distributed copies of the FS report to more than
40 people, including those who requested a copy during the
public comment period. EPA sent copies on July 6, 1987 of
the FS report to all defendants in United States v. Apache
Energy and Minerals Co. and invited their comments.
On August 17, 1987, EPA issued a press release announcing
the availability of the proposed remedial action plan •'for
the Yak Tunnel operable unit. EPA placed a full-page notice
in The Herald Democrat on August 20, 1987, which contained a
brief analysis of the plan and alternative plans that were
considered. The notice also provided information on the
comment period and the date set for a public meeting. EPA
sent copies of the proposed plan to the complete mailing
list and to each of the defendants in United States v.
Apache Energy and Minerals Co. The plan notified the public
and the defendants of the timing and procedures for comment.
Copies of the proposed plan were also placed in the Lake
County and EPA Region VIII libraries.
EPA also made copies of the administrative record available
in the Lake County and EPA Region VIII libraries on
September 15, 1987. EPA sent letters to each defendant
announcing the availability of the administrative record.
EPA also issued a press release on September 25, 1987, and
articles notifying the public of location and availability
of the record appeared in The Herald Democrat on October 1,
1987, and the Rocky Mountain News on October 2, 1987. EPA
responded to all requests made during the public comment
period by defendants and others for technical information
not yet available in the administrative record.
In addition to a 90-day public comment period, EPA held a
public meeting on the FS and proposed plan at the Lake
County Courthouse in Leadville on September 1, 1987. More
than 40 people signed the attendance sheet. Attendees
19

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.although reduced, threats to worker safety. There is also
uncertainly about how plugging would affect the quality and
flow of water behind the plugs. The primary concern would
be uncontrolled seepage or contamination of clean ground
water areas. Some members of the community are opposed to
the plugging component for these reasons.
Alternative 11—No Action
This alternative is not protective of public health and the
isnvironment because the contribution of the Yak Tunnel to
contamination of surface water, ground water, and the
jediment system would continue unabated. In addition, the
.risk of surges would continue, the chemical-specific ARARs
would not be attained, and there would be no reduction in
nobility, toxicity, or volume of the contaminants. This
alternative is not acceptable to the State or the community.
Alternative 12—Total Plugging, Collection, and In Situ
Treatment
This alternative would be protective of human health and the
environment through the decrease in both chronic metals
discharge and periodic surges. The remedy would reduce the
mobility and volume of contaminant* released into the
environment through partial inundation of the sulfide zone
end blockage of water behind the plugs. The in situ
v.roatment component of the remedy would further reduce the
mobility of contaminants and could minimize the need for
ebove-ground landfill disposal of sludge. The remedy is
ijnplementable using existing technology and the in situ
treatment component offers the potential for a permanent
iiolution. Some community members supported this alternative
principally due to its potentially lower costs and possible
elimination of the need for perpetual operation and
maintenance.
Alternative 12 also has significant drawbacks. Due to the
complexity of the mine workings, there is a significant
possibility that in situ treatment, as proposed, would not
achieve sufficient mixing and would, thus, ineffectively
treat water in all areas of the tunnel and connected mine
forking*. Sludge from the treatment system may seal off
fracture flow paths causing short circuiting of the system,
thus rendering the treatment ineffective. Consequently, as
vater levels rise behind the portal plug, there could be
vmcontrolled seepage of water that would not meet
chemical-specific ARARs. Surface seeps of contaminated
vater or movement of contaminated ground water toward clean
vater areas could necessitate operation of a pumping and
treatment system, perhaps in perpetuity. This would negate
the benefits of in situ treatment and would result in
long-term maintenance and sludge disposal requirements.
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There is also a concern that buildup of sludge in the old
mine workings, which would result from in situ treatment,
would interfere with future resource development. The
concern is that it would be difficult to collect, remove,
and treat the sludge. The State believes that the
uncertainty associated with the effectiveness of in situ
treatment should be resolved through further study prior to
implementation of that system.
Alternative 13—Partial Plugging and Discharge
This alternative would be protective of public health and
the environment in that it would reduce flow fron the Yak
Tunnel by 20 to 25 percent. After mining ceases, the remedy
would reduce both the mobility and volume of contaminants
through inundation of mineralized zones and by blocking the
discharge of additional effluent from the Yak Tunnel. The
remedy is implementable using existing technology for
plugging and is expected to be a permanent remedy for that
portion of the tunnel. The State and many community members
support construction of a plug below the Resurrection
workings.
This alternative is not a total solution. There would still
be substantial flow from the Yak Tunnel and the discharge
would exceed chemical-specific ARARs. Additionally, the
Leadville Corporation proposal did not provide for monitoring
or contingency planning, which would be necessary to ensure
that plugging did not result in unacceptable environmental
impacts.
VI. SELECTED REMEDY
The goal of the selected remedy is to decrease the release
and threatened release of hazardous substances, pollutants
and contaminants from the Yak Tunnel into California Gulch.
The selected remedy consists of the following components:
o Surge ponds t
o Tunnel plugging;
o Water control measures, including sealing of drill
holes# shafts, and caved-in underground mine
workings to reduce surface inflow to the Yak
Tunnel system, and grouting of other areas to
minimize ground water outflow from the flooded
tunnel system after plugging;
o A monitoring system, including surface and ground
water components, to determine hydrologic changes;
34

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o A water collection (pumping) system to control
water levels behind the lower plug and an interim
water treatment facility using ponds (built
originally for surge control) as settling ponds;
o Operation and maintenance of components of the
remedy; and
o Contingency plans.
The components of the remedy are shown schematically in
figure 5. Many of these components are part of various
alternatives described in the previous section and were
evaluated in the FS. Specific design details of the
selected remedy will be developed during remedial design.
This remedy differs from the remedy described in the
proposed remedial action plan (EPA, 1987c). EPA initially
identified Alternative S as the preferred remedy but
retained the option to incorporate a partial plugging
component. Subsequently, EPA received additional
information during the public comment period and, after
taking these comments into consideration, re-evaluated
alternatives containing a plugging component and various
treatment options. Based on the comments received, EPA also
modified the remedy to reflect concerns about integration of
the Yak Tunnel operable unit into the overall site remedy.
DESCRIPTION OP SELECTED REMEDY
The selected remedy for the Yak Tunnel operable unit
consists of the components described above. The remedy
incorporates a source control technology (tunnel plugging)
and a manag«ment-of-migration technique (a mine water
collection and treatment system). Each component is
described in more detail below.
Surge Ponds
Before the plugs are installed in the Yak Tunnel, a surge
pond system will be constructed at th« portal. To protect
California Gulch and the Arkansas River from accidental
release*, the ponds will collect any surges of acidic
waters, sludges, or sediments from the tunnel caused by
construction. The ponds will be. large enough to contain
approxinat«ly 8 million gallons of water, or about six to
eight times the discharge volume that was estimated during
the October 1985 surge event (EPA, 1987b). The ponds and
suitably sized ditches will b« excavated to maintain a
working depth of about 10 feet. The ponds will be lined
with a synthetic membrane and clay to minimize leakage. A
35

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bypass channel, sized to accommodate the flow from a
100-year -flood event from upper California Gulch, will be
built to protect the surge ponds. Once the tunnel plugs
have been installed, the ponds will not be needed for surge
control. They will then be used as part of the interim
treatment facility, which is described later in this
subsection.
Tunnel Plugging
A minimum of three concrete plugs will be installed in the
Yak Tunnel as shown in Figure 5. The plugs will be
constructed in sound, low permeability rock, and will be
downgradient from each major group of interconnected mine
workings (Resurrection Group, lbex-Irene Group, and the Iron
Hill Group). The Resurrection plug will be located in the
vicinity of the small rhyolite breccia pipe that separates
the Resurrection Mine Group from the Ibex-Irene Group.
Installation of the plug will reduce inflow to the Yak
Tunnel from the Resurrection group. The Ibex-Irene plug
will be located just to the west of the Weston Fault Zone
within the large mass of gray porphyry rock underlying
Breece Hill. This plug will reduce mine water drainage from
the Ibex-Irene group to the Yak Tunnel. The portal plug, to
be built just below the Iron Hill group of mine workings,
will probably be placed about 1,500 feet inside the tunnel
portal because of the highly weathered rock (fractured) and
generally unstable tunnel condition near the portal.
Access for construction of the Resurrection and Ibex-Irene
plugs can initially be gained through either the
Resurrection workings or the Irene 1,200 lateral (see
Figure 5). Construction access for the portal plug will
require either tunnel rehabilitation or construction of a
new access shaft.
Plugging will seal off the major flow route for ground water
movement. As a result, ground water levels in the mine
workings and the surrounding rock will rise to a new
equilibrium level. The current equilibrium ground water
level in the vicinity of the Yak Tunnel is at the floor
elevation of the tunnel, which is approximately 10,330 feet
msl. The tunnel acts as a drain for the mine workings and
the surrounding fractured rock. It can collect surface
infiltration and ground water located in the rock mass up to
several thousand feet from the tunnel. This low ground
water level throughout the mine workings and mineralized
rock results in a maximum exposure of sulfide-bearing rock
where it is subject to oxidation. These conditions are
conducive to acid mine drainage formation and result in the
high metals concentrations in the Yak Tunnel portal flow.
The approximate maximum elevation of sulfide rock in the
Resurrection group of workings is estimated to be
36

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10,700 feet msl and in the Ibex-Irene Group, 11,300 feet
msl. In-the Iron Hill Group, it is at approximately
10,700 msl? however, it rises to approximately 11,300 feet
msl in the unmined segment of rock between the Iron Hill
Group and the Ibex-Irene Group.
Plugging will cause ground water levels to rise to a new
equilibrium level. At this new level, the outflows through
fractured rock, to the surrounding regional ground water
bodies, or in some cases through surface seeps, would
balance the recharge. This new equilibrium level is,
therefore, a function of the average permeability and amount
of mining-induced fracturing of the rock mass surrounding a
group of mine workings behind a particular plug. The rise
in ground water level can inundate all or portions of the
exposed sulfide rock, thereby preventing exposure to oxygen,
and hence, reducing the amount of acid mine drainage that
forms. A simple ground water balance model was developed to
determine the approximate impacts of plugging on ground
water level, flow directions, and quality. It is based on
the model used in the FS report. A detailed description of
the model and the results of the analyses are outlined in
Appendix A. A summary of the result is contained in the
following paragraphs.
Immediately following installation of the plugs, ground
water levels will begin to rise behind the plugs, reducing
flow from the Yak Tunnel to near zero. Based on estimates
of rock permeability, the equilibrium ground water level
behind the Resurrection plug is expected to rise to
approximately 10,750 feet msl. This should be sufficient to
inundate the sulfide rock and reduce acid mine drainage
formation to a minimum. Furthermore, since the surface
topography in this area is above 11,100 feet msl, no surface
seeps should develop. Should the Black Cloud operation
cease to pump its mine water, the ground water level in the
Resurrection area may increase to approximately 10,900 feet
msl. At this elevation, a ground water flow component from
the mine workings toward the Evans Gulch area could occur.
In addition, there is a possibility that the selected remedy
may affect the Leadville Drainage Tunnel (LOT), which is
owned by the Bureau of Reclamation. EPA recognizes the
concern of the Bureau of Reclamation over the effect
plugging the Yak Tunnel may have on levels of ground water
contamination and flow. Currently, the Bureau is seriously
considering construction of a treatment plant to remove
38

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heavy metals from the effluent discharged from the ne
LOT. Attention must be focused on avoiding a change
quality or quantity of flow toward the area drained fc
LOT that would alter the LOT discharge and exceed th«
capabilities of the Bureau's proposed treatment faci:
Once the Yak Tunnel is plugged, EPA's conceptual mod*
suggests a slight increase in ground water flow in t
general direction of the LOT, from 10 to 25 gpm (0.0
0.05 cfs). EPA believes this potential increase in
will not adversely affect the Bureau's treatment fac
However, if EPA has underestimated the actual changt
that results from plugging, as discussed below, the
remedy includes an extensive ground water monitorin-
that is intended to identify any adverse change in
contamination in a time frame that would permit the
systems included in this remedy to alleviate the pc
problem. In any event, EPA intends that the select
be designed and implemented in a manner that will :
adversely affect the Bureau's LOT treatment facili
subjecting it to unanticipated ground water flow o
contamination.
The equilibrium level in the Ibex workings behind
is expected to ris* to about 10,650 feet msl. In
area, the level is expected to be much lower due
influence of mine water pumping from the Black CI
workings. These levels are insufficient to inunc
sulfide rock; acid mine drainage formation will j
continue. Ground water from this area is expect<
in a westerly and southerly direction. Because
topography in this area is generally above 11,00
no surface seeps are expected to result. Should
Cloud Mine cease pumping, the equilibrium level
to approximately 10,800 feet msl in both the Xb<
Groups. This level is still inadequate to prev-
drainage formation but is still low enough not
surface seeps in the area.
The equilibrium ground water level behind the i
difficult to predict because the rock in the a:
extensively fractured and faulted, and near~su
workings are present. It is, therefore, not p
estimate the permeability of this rock mass wi
of reliability. Without sealing of these frac
contaminated mine water will seep to the surf:
locations as the water levels rise behind the
As described below, the selected remedy inclu
these highly fractured rock areas and other w
measures. If these measures are successful e
equilibrium level of 10,500 feet msl can be <
of the sulfide rock exposed in the mine work
inundated. However, sulfide rock at the eas
39

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the v/orkings and in the unrined rock between the Iron Hill
Group and .the Ibex-Irene plug will still be exposed and
contribute to the development of acid mine drainage.
Due to the large, geologically complex area potentially
affected by installation of the portal plug, without
full-scale field testing it is impossible to predict the
effectiveness of plugging and sealing in controlling the
release of acidic waters. Should uncontrolled seepage
continue after extensive sealing, the water level behind the
plug would be lowered by using a pumping svstem to the point
at which seepage would not occur. Contaminated waters from
the workings behind the portal plug would be pumped,
treated, and released to California Gulch. Details of the
pumping and treatment system are discussed later in more
detail.
Water Control Measures
During the RI, it was determined that there is recharge to
the Yak Tunnel drainage system from surface waters entering
through shafts and caved-in areas. This recharge adds to
the amount of contaminated waters generated in the mine
workings. To reduce infiltration to the system, actions
will be taken to seal shafts and other recharge areas, and
to prevent infiltration of surface waters from known or
suspected recharge areas such as the White Cap lateral east
of the Yak Tunnel portal.
As mentioned previously, after the plug i3 installed, water
levels will rise behind the portal plug. Fracture zones,
caved-in areas, and drill holes will becdme leakage points
that must be located and grouted with acid-resistant
concrete to prevent the surface discharge of acidic waters.
Additional geologic mapping, geophysical investigations, and
other site activities will need to be conducted during the
design phase to address the sealing of these surface
infiltration and leakage locations.
Monitoring
Because of the size and complexity of the Yak Tunnel system,
tunnel plugging presents a risk of uncontrolled seepage and
migration of contaminated ground water. Therefore, the
monitoring program is an integral part of the remedial
action. The general objectives of the program are as
follows:
o Define the preremediation ground water and surface
water conditions against which the impacts of the
selected remedy can be evaluated;
40

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California Gulch
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Phase I Remedial Investigation Report,
California Gulch, Leadville, Colorado;
EPA Region VIII; May 1987

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EXECUTIVE SUMMARY
INTRODUCTION
Th«i California Gulch Super fund site is located in and near
Leadville, Colorado/ which is approximately 100 miles south-
west of Denver. Surface water and groundwater from the
11. 5-square-ntile study area are contaminated with iron, zinc,
caclmium, lead, copper, manganese, and other metals. Poten-
tial contaminant sources include the Yak Tunnel, which is a
major underground mine drainage system, and various types of
mine wastes found throughout the study area.
Water can react with som* of these mineralized wastes, fdrm
ac:Lda, and mobilize (dissolve) heavy metals. Contaminated
wai:ers drain into California Gulch and subsequently into the
Arkansas River~
SITE DESCRIPTION AND BACKGROUND
This site is situated in a highly mineralized area of the
CoLorado Rocky Mountains, with elevations ranging from
9,520 feet to approximately 14,000 feet above sea level.
/"Tha development of Leadville dates back to the 1850 's with
the minings development of the rich mineralized zones con-
taining principally gold, silver, lead, zinc, and copper.
Mining, processing, and/or smelting operations in the area
have been active for more than 125 years and varied in
degree with economic demand and technological improvements.
Early activities consisted of placer mining for gold in
California Gulch. Later, underground mines were developed
to the southeast of Leadville where the ores were extracted
and then processed into metallic concentrates. These
DE:/CALGU8/026
ii

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concentrates were either shipped elsewhere or £urther pro-
cessed at the-numerous smelters that were in the Leadville
area. Many areas o£ the site received mining-related wastes
including mine waste rock, tailings, and slag piles.
Tunnels were developed to drain the ore bodies and to facil-
itate mining. The YaJc Tunnel, developed from 1895 to 1923,
extends approximately 4 miles into Iron Hill, which is
located in upper California Gulch. The tunnel drains numer-
ous underground mines. The tunnel drainage water discharges
into California Gulch, which flows 4.5 miles west to the
Arkansas River.
Mining activity has declined to a much slower pace due to
lower metal prices. Presently there are only a few moder-
ately sized mining operations in the Leadville area, and the
Leadville population has decreased significantly from past
levels.
SUPERFUND PROCESS
Under Section 104(a) of the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA or
also known as Superfund), and the Superfund Amendments and
Reauthorization Act of 1986, (SARA), the United States
Environmental Protection Agency (EPA) is authorized to
respond to the actual or threatened releases of hazardous
substances, or pollutants and contaminants that may present
an imminent and substantial danger to public health or wel-
fare. This process involves several steps but discussion
here is limited to a remedial investigation (RI).
The purpose of the RI is to determine the nature and extent
of the problem presented by the release of hazardous
DE/CALGU8/026
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o Three major tailings impoundments in California
Gulch
o Starr Ditch, which intercepts the drainage from
the north side of Iron and Carbonate Hills (Stray
Horse Gulch)
o Oregon Gulch tributary, which contains a fourth
major tailings impoundment
o Storm drains from Leadville
o Other tributary drainages
o Slag pile areas near Stringtown
o Discharge from the Leadville sewage treatment plant
(STP)
A detailed water quality monitoring plan and a soils/tailings
geocliemical sampling and testing plan were developed to eval-
uate these potential contaminant source areas.
The surface water sampling program included the installation
of f.Lve Par shall flumes to provide continuous flow measure-*
mentis. These were located at the Yak Tunnel discharge; in
the upper Gulch above the three tailings impoundments; in
Star:r Ditch; and two in lower California Gulch. In addition,
17 supplemental sampling and flow measuring points were
selected at critical locations along the drainage to be used
when flows were present.
The groundwater sampling program included the use of numerous
privately owned wells at critical locations and the instal-
lation of 21 new monitoring wells. The new wells were designed
and Located to provide more reliable data than were available
DE/CALGU8/026
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from the privately owned wells. To provide more information
on water exchange between surface water and shallow ground-
water, piezometer pipes were installed at various locations
in the Gulch and water levels were taken on one occasion.
The preliminary soils/sediments and tailings characterization
program consisted of collecting one surface sample from each
of the four major tailings impoundments and two samples near
the confluence of the Gulch and the Arkansas River. These
samples were tested and categorized as characteristic or
noncharacteristic waste.
The hydrologic cycle for this region has a significant
influence on the mobilization and transport of contaminants.
Snowmelt in May and June causes a large surface water runoff
to occur during this period; whereas surface flows are more
constant for other periods of the year with the exception of
winter when hard freezing occurs. To take this into con-
sideration, a long-term surface and groundwater sampling
program was conducted during* the Phase I RI. Using the
sampling network previously described, water sampling was
conducted in October and November 1984; and in March, June,
September, and November 1985. Two aquifer pump tests were
also conducted in November 1985.
NATURE AND EXTENT OF CONTAMINATION
Major findings and conclusions determined from the Phase I
RI are summarized as follows:
1. The predominant geochemical system in the-project area
is an acid-sulfate system caused by the oxidation of
sulfide minerals. Interactions among surface water,
groundwater, and the sulfide minerals generate acid
DE/CALGU8/026
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that reacts with other minerals to release dissolved
metals such as lead, copper, cadmium, iron, manganese,
zinc, and iron to the waters on the site.
2.	The acid forming and dissolution reactions occur at
widely differing rates depending upon hydrologic and
geohydrologic conditions and the type of metal bearing
materials they contact. The site is very large; the
hydrologic and geohydrologic regimes vary from location-
to-location with the topography, geology, and other
surficial characteristics. The solids that the waters
react with vary dramatically in chemical composition.
The site is extremely complex geochemically.
3.	Analytical results of the soils/sediments and tailings
samples varied widely in metals content. For example,
two tailings samples and one soils/sediment sample were
very high in iron content, indicating a high concentra-
tion of iron pyrite (a strong acid generator). The
othor tailings samples and soils/sediment samples had
dramatically lower iron contents.
4.	EP-Toxicity tests for characteristic waste on soils/
sediment and tailings samples determined that one tail-
ings sample failed the criteria for cadmium and one
soils/sediment sampled failed for lead. It should be
noted that erosion in the drainage system by surface
water from the hundreds of waste piles, and from tail-
ings and slag areas make soils/sediment characterization
extremely difficult.
5.	Surface water flows in the site drainage system act as
the primary contaminant transport system for soluble
metal contaminants as well as metal-laden sediments.
Flow data indicate that the California Gulch mainstem
DE/CALGU8/026	vii

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accepts continuous flows from both the Yak Tunnel and
STP discharge. Other tributaries to the Gulch are
ephemeral and generally only flow during snowmelt (May
and June) and during high intensity summer thunderstorms.
Representative high and low flows appear to occur in
June and November, respectively.
6. Surface water quality information is extensive over the
five sampling periods. Comparisons of surface water
quality results with primary drinking water standards
(called "maximum contaminant levels* or "MCL's") and
federal water quality criteria for fresh water aquatic
life listed for comparative purposes are summarized as
follows:
o Cadmium has a primary MCL of 10 micrograms per
liter (ug/1) and a chronic aquatic life criterion
of 1.1 ug/1- Cadmium concentrations in California
Gulch ranged from 12' ug/1 in upper California Gulch
to 431 ug/1 at the tailings area. In the ephemeral
drainages, cadmium ranged from detection level to
380 ug/1 in Oregon Gulch. The Yak Tunnel discharge
varied in cadmium concentration from 169 ug/1 to
552 ug/1.
o Copper has a chronic aquatic life criterion of
11.8 ug/1* Copper concentrations in the Gulch
ranged from 20 ug/1 near the slag area to
4,670 ug/1 just below the Yak Tunnel. In the
ephemeral drainages, copper ranged from 3.3 ug/1
in Georgia Gulch to 9,520 ug/1 in Oregon Gulch.
Copper in the Yak Tunnel discharge varied from
437 ug/1 to 5,970 ug/1.
o Iron and manganese in the California Gulch and its
tributaries ranged from 152 ug/1 to 677,000 ug/1
DE/CALGU8/026
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for iron, and manganese concentrations ranged from
146_yg/l to 708,000 uc/1.
o Lead has a primary MCL of 50 ug/1 and a chronic
aquatic life criterion of 3.2 ug/1. Lead concen-
trations in California Gulch ranged from detection
to 382 ug/1 in upper California Gulch. In the
ephemeral drainages, lead values varied from detec-
tion to 310 ug/1 at Oregon Gulch. The Yak Tunnel
discharge ranged from detection to 116 ug/1.
o Zinc has a chronic aquatic life criterion of
86 ug/1- Zinc concentrations in California Gulch
varied from 1,506 ug/1 to 35,300 ug/1 in upper
California Gulch. The Yak Tunnel discharge ranged
from 43,700 ug/1 to 109,000 ug/1.
o Water quality at the Arkansas River upstream of
California Gulch routinely exceeded the aquatic
criterion for zinc.
o Water quality at the Arkansas River downstream of
California Gulch met primary MCL's for all periods
except March 1985, when the cadmium standard was
exceeded. Aquatic criteria were routinely exceeded
for zinc and cadmium.
7. Surface water data further indicate that some dissolved
metals (cations) such as zinc and cadmium stay princi-
pally in dissolved form in the surface waters along the
Gulch. Other cations 3uch as iron,'aluminum, and to a
lesser degree, manganese, are oxidized and precipitated
as oxy-hydroxides. These precipitates have a high sorp-
tive capacity and can remove other dissolved metals
from solution. These precipitate settle to the bottom
of the drainage at low flows.
DE/CALGU8/026
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During snowmelt, higher stream velocities carry more
sediments from various waste areas. These mix with the
previously settled sediments and precipitates that are
then re-entrained in the water. The buffering, precipi-
tation, and re-entrainment further complicate water
chemistry interpretation. For this reason, zinc,
cadmium, manganese, and sulfate are used to further
study the system since they are the most mobile.
8.	Review of the data for groundwater indicates that ground-
water chemistry, particularly dissolved metals concen-
trations , is more strongly affected by depth than by
location along California Gulch. The water level data
demonstrated that recharge and drainage is most active
in the shallow alluvial material and decreases with
depth. The groundwater chemistry reflects the active
exchange between surface water and groundwater. Specific
conductancet a measure of the total ionic material dis-
solved in the water, including metals, is highest in
the upper 25 to 5Q feet of the California Gulch allu-
vial groundwater.
9.	Groundwater quality data for the five sampling periods
is extensive. Primary drinking water standards (MCL's),
secondary drinking water standards (secondary MCL's),
and proposed "maximum contaminant level goals" were
listed for comparative purposes. Preliminary observa-
tions from these comparisons are summarized as follows:
o Sulfate is closely associated with the oxidation
of sulfides'. Sulfate, like specific conductivity,
decreases with depth. The mean sulfate concentra-
tion in the upper 25 feet of the California Gulch
alluvium ranges from less than 100 mg/1 to more
than 1,000 mg/1. The secondary MCL is 250 mg/1.
DE/CALGU8/0 2 6
x

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Many of the private and new wells in the
California Gulch alluvium exceed this concentra-
tion, particularly those completed in the upper
50 feet of the alluvium.
Manganese, zinc, and cadmium are trace metals that
are quite mobile in the groundwater system; iron
and lead are not very mobile in oxidized, sulfate-
rich groundwater. Manganese, zinc, and cadmium
were used to determine the extent of vertical con-
tamination in the California Gulch alluvial
groundwater system resulting from recharge from
the surface water.
Manganese has a secondary MCL of 50 ug/1. Manganese
concentrations in groundwater in the upper 20 feet
of the alluvium ranged from below the standard to
as much as 15,000 ug/1. In the 20- to 50-foot
depth range, manganese concentrations decrease to
less than 4,000 ug/lr below 50-foot depths, man-
ganese generally meets the standard.
Zinc has a secondary MCL of 5,000 ug/1. Zinc con-
centrations in the groundwater are highest in the
upper 25 feet of the alluvium ranging from below
the standard to as much as 35,000 ug/1. Zinc con-
centrations in the 25- to 50-foot depth range from
below standard to as much as 1,000 ug/1. Below an
approximate 50-foot depth, the typical zinc con-
centration is less than 500 ug/1*
Cadmium has a primary MCL of 10 ug/1. Like man-
ganese and zinc, the highest concentration of
cadmium is found in the upper 25 feet of the
California Gulch alluvium. Concentrations range
/ 026
xi

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from below the drinking water standard to as much
as 100 vi?/1* Mean cadmium concentrations decrease
to less than 10 ug/1 in the 25- to 50-foot depth
ranges and to less than 5 ug/1 in deeper parts of
the groundwater system.
o The upper 25 to 50 feet of the California Gulch
groundwater system contain metals in concentra-
tions in excess of both primary and secondary
drinking water standards. These excessive concen-
trations result in part from infiltration of
California Gulch surface water.
o A number of privately-owned wells exceeded primary
MCL's. Four wells exceeded the cadmium limit of
10 ug/1. Typically, the exceedance ranged from
10 ug/1 to 116 ug/1r but one well ranged from
28 ug/1 to 1,124 ug/1 for all sampling events.
One well exceeded the lead limit of 50 ug/1* It
was measured of 296 ug/1 in November 1984. This
value is suspect since lead was not detected on
four subsequent sampling events.
10. Based upon review of surface water flows and chemistry,
groundwater levels and chemistry, and data from the
piezometer program, it was suspected that the shallow
groundwater system was intimately connected with the
Gulch mainstem surface waters. Chemical profiles were
developed along the Gulch for the surface water and
groundwater systems. Seasonal flow and water level
differences were also considered. This analysis sup-
ported the postulation that surface water/shallow allu-
vium groundwater is acting as a single conduit along
which contaminated waters move to the Arkansas River.
Pump tests also indicated no significant groundwater
DE/CALGU8/026
xii

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contribution from the Gulch alluvium directly to the
Arkansas River.
11. Based upon the single conduit theory, it was possible
to conduct a mass loading analysis to better define
areal and point source contribution of contaminants to
the Gulch mainstem. Mass loadings were calculated
along the Gulch conduit for each sampling event using
appropriate surface water chemistry and flow data. The
individual mass loading analyses were then adjusted for
the contribution during snowmelt to determine average
annual contaminant contributions from the suspected
sources, considering the mobile ions such as zinc,
cadmium and sulfate. Results of this analysis are sum-
marized as followst

Zinc
Percentages
Of
Source
Cadmium
Sulfate
FaJc Tunnel
80.4
84.9
74.7
Upper Gulch.
4.3
7.0
6.1
Stray Horse Gulch (Starr Ditch)
2.0
3.5
1.8
Oregon Gulch
1.6
0.5
5.6
Slag Area
1.9
0.2
3.9
Sewage Treatment Plant
0.4
0.7
3.7
Miscellaneous Tributaries
8.9
3.3
4.2
NOTE:These percentages are not necessarily representative
for other specific contaminants.
PHASE II RI SAMPLING PROGRAM
Completion of the Phase I RI has provided an indication of
water quality problems at various locations in the study
area? probable sources and relative contribution of contami-
nants to the water system; and an initial assessment of the
hydrology, geology, geohydrology, and geochemistry of the
system.
DE/CALGU8/026
xiii

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in order to complete the site FS, the following data are
needed to permit further characterization of contaminant
sources:
o	Tailings stability and surface chemistry
o	Waste dump stability, surface and bulk chemistry
o	Slag stability and bulk chemistry
o	Air quality data
o	Sediment chemistry
o	Seismic activity in the study area
o	Soil data in the Stray Horse Gulch drainage
o Information to approximate baseline chemistry of
soils, surface water, and groundwater
o Additional surface water flow, groundwater levels,
and water chemistry during snowmelt runoff
Data gathered will be synthesized and published as the
Phase II RI report.
DE/CALGU8/026	xiv

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Within the study area there are several types of mining and
processing wastes. The major types and locations are as
follows:
o Four major inactive tailings impoundments. Three
major tailings impoundments are located in California
Gulch between the Resurrection Mill Yard and Harrison
Street. The fourth impoundment is in Oregon Gulch.
o Three major slag piles. One pile is located on
Harrison Street and two piles are located near
Stringtown.
o Over 2,000 waste dumps, varying in size from a few
tons to several hundred thousand tons. These dumps
are located in upper California Gulch, Stringtown,
Carbonate Hill, and Stray Horse Gulch. Some of
the piles in Stray Horse Gulch are near residential
areas. Many of these dumps contain mixed types of
waste including tailings, waste rock, and low grade
ore, which was not economical to process at the
time.
Tunnels were developed in the area to drain ore bodies and
facilitate mining. The Yak Tunnel, developed from 1895
through 1923, extends approximately 4 miles into Iron Hill
and Breece Hill, which are southeast of Leadville. This
tunrel drains water from numerous sulfide and carbonate
underground mines. The tunnel empties into California Gulch,
which in turn conveys these mine waters westward 4.5 miles
to t.he Arkansas River.
DE/CALGU6/0 03
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Section 2
SITE DESCRIPTION
The California Gulch site encompasses an 11.5-square-raile
study area, which includes Leadville and its outlying area.
The study area is shown in Figure 2-1. The main features of
the study area are described below.
The major surface water drainage is California Gulch (here-
after called "the Gulch"), which receives water from a number
of ephemeral drainages: upper California Gulch, Stray Eorse
Gulch, Oregon Gulch, Starr Ditch, Georgia Gulch, Pawnee Gulch,
Airport Gulch, and Malta Gulch. The Gulch empties into the
Arkansas River at the western boundaries of the study area.
Plates 2 and 3 show these various surface water drainages.
The four major tailings impoundments within the study area
are located in Section 25 of Township 9S, Range 80W. There
are three major impoundments in California Gulch and one in
Oregon Gulch (Figure 2-1). Plate 4 shows two of these
tailings impoundments.
From recent aerial photographs, over 2000 waste dumps have
been identified within the study area. These dumps range in
size from a few tons to over 100,000 tons; they are primarily
located in upper California Gulch, Carbonate Hill, Stringtown,
and Stray Horse Gulch. Many of these dumps are near shafts
or portals, which are indicated on Figure 2-1. Plates 5 and
6 show typical waste dumps in upper California Gulch and
Stray Horse Gulch.
There are three large slag piles within the study area. One
pile is located on Harrison Street (within Leadville city
limits) and two are located near Stringtown. Plate 7 shows
the Harrison Street pile and one of the Stringtown piles.
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The Yak Tunnel, which discharges metal-laden water to Cali-
fornia Gulch, is located just east of the Resurrection Mill
Yard. Plate 8 shows the Yak Tunnel portal.
The city of Lea'dville is part of a Historic Mining District.
Since the mid-1800's, mining activities have been prevalent
within the boundaries of the site. The area has been exten-
sively disturbed by past mining activities (Emmons, et al.,
1927; Emmons, 1886; Griswold, 1951; Tweto, 1963).
SITE CHARACTERISTICS
The following subsections present a background description
of the physical characteristics of the site. This includes
information regarding geology, soils, surface water, ground-
water, vegetation, wildlife, climate, etc* These character-
istics are influenced to varying degrees by the effects of
the sulfide minerals and mineral development activities
present within the study area. Lake County, which includes
the Leadville Mining District, is located within the
Colorado Mineral Belt. This belt (see Figure 2-2) is a geo-
chemically enriched zone that is present in the central
Colorado mountains (Tweto, 1963) . Elevations within the
site range from 9,520 feet above Mean Sea Level (MSL) to
approximately 14,000 feet MSL. The low point is at the
confluence of California Gulch and the Arkansas River.
GEOLOGY
The Upper Arkansas River Valley is located between the Mos-
quito Range to the east and the Sawatch Range to the west.
California Gulch drains from the western slope of the Mos-
quito Range and cuts through glacial and glaciofluvial
sediments on its way to the Arkansas River.
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Taylor (1979) and Topielec (1977) estimate depth to bedrock
near the Arkansas River to be 600 to 800 feet. The upper
unit (high terrace gravels), appears to be in excess of
50 feet thick near the Pendry Fault and thickens to several
hundred feet in depth near the Arkansas River. Placer opera-
tions and disposal of mine wastes probably altered the sur-
face features of this stratigraphic unit. Existing wells in
the middle and lower sections of the Gulch typically pen-
etrate the upper stratigraph unit.
Recharge to the aquifer system is principally from infiltra-
tion of snowmelt and rainfall. The average annual precipi-
tation is approximately 13 inches. Observed fluctuations in
the water table indicate that recharge occurs principally
during the snowmelt, and that short duration summer thunder-
storms are of little consequence (Turk and Taylor, 1979).
SURFACE WATER
The upper Arkansas River headwaters start at an elevation of
12,540 feet MSL, and the mainstem flows downstream past Lead-
ville over 34 miles to its confluence with Lake Creek at an
elevation of 9,038 feet MSL. The drainage system includes
877 miles of tributaries, in addition to the mainstem. This
stream system joins the mainstem Arkansas River that flows
eastward across Colorado. Further information, including a
stream order analysis, profiles, and seasonal flows, is pre-
sented in the Hydrology section of the IA.
California Gulch drains approximately 7,400 acres of water-
shed into the Arkansas River (see IA Hydrology section).
The mainstem of the Gulch receives water from several ephem-
eral drainages: Starr Ditch, upper California Gulch, Oregon
Gulch, Georgia Gulch, Pawnee Gulch, Airport and Malta Gulches,
etc. It also receives perennial discharges from the Yak
Tunnel and the Leadville Sewage Treatment Plant (ST?).
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Starr Ditch drains Stray Horse Gulch and other areas east of
Ieadville.Average flow at the Gulch's confluence with the
Arkansas River ranges between 2.2 and 6.4 cubic feet per
second (cfs) (LaBounty, 197S) with infrequent flood flows
also being observed. Flooding at this elevation usually
occurs as a result of rapid snowmelt in May and June. The
10-year, 7-day low flow in the Arkansas River at the Cali-
fornia Gulch confluence is about 24 cfs. Low flows observed
from the Yak Tunnel are about 1.1 cfs. The balance of Cali-
fornia Gulch low flow is approximately 1.0 cfs being contri-
buted by the STP. Combining these flows yields a normal low
flow of about 2.1 cfs at the Arkansas River confluence, which
produces a dilution ratio of approximately 11 (LaBounty,
1975). Digerness (1977) indicates that prior to constructior
of the Yak Tunnel and the STP, California Gulch was an ephe-
meral system. It was noted, that various ditches, including
the Starr Ditch, were built in the late 1860's to convey
water for placer mining operations to California Gulch from
isvans Gulch.
The flood potential in the area, particularly in the upper
Gulch, is quite high because of relatively sparse vegetation.
The Corps of Engineers (COE, 1983) estimates the upper Cali-
fornia Gulch channel capacity at SO cfs. Their estimate of
the 100-year flood event is 270 cfs at the confluence of the
'julch and the Arkansas River and, by ratio, 90 cfs at the
?ak Tunnel portal. Investigation of historic and. paleogeo-
Logic floods at this elevation indicates the worst floods
accur during snowmelt and not from short duration, high-
intensity thunderstorms during the summer months (Turk and
Taylor, 1979). Using data from COE (1983) the 100-year flood
plain was estimated and is shown on Figure 2-6. Potential
wetlands within the Gulch were identified from aerial photo-
graphs (EPA, 1982) , and are shown on the same figure.
DE/CALGU6/007
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VEGETATION
The species diversity and percent cover of vegetative com-
munities of California Gulch are limited in the drainage
bottoms. This has been caused by physical disturbances as-
sociated with the presence of tailings impoundments and waste
piles., and placer activities. Small pines and aspen grow
alongside the Gulch in the upper portions of the drainage.
A wide variety o£ vegetation exists in the upper Arkansas
River- Basin, primarily because of the variation in elevation.
Elevations within the site range from 9,520 feet MSL to
approximately 12,200 feet MSL. The higher elevations follow
the Carbonate Hill-Iron Hill ridge that separates California
Gulch from Stray Horse Gulch. Timberline occurs at approxi-
mately 11,500 feet MSL; the vegetation above that elevation
is alpine tundra. The tundra is composed of grasses, sedges,
and herbs. In the Subalpine Zone (10,000 to 11,500 feet
MSL) , the existing forests are dominated by Bnglemaxm spruce
and Alpine fir. Stands of aspen and lodgepole pine can also
be found in this Subalpine Zone. In the valley bottoms around
Leadville (9,000 to 10,000 feet MSL), sedge-grass meadows
are common, and marshy areas along stream banks support wil-
lows and dwarf birch (Topielec, 1977).
Areas: southwest of Leadville are in the Montane Zone (8,000
to 1C,000 feet MSL). Douglas fir and Ponderosa pine are
found in this zone. Open or transition areas, such as the
Maltai Gulch area, may contain bearberry and juniper; stands
of asipen and lodgepole can be found. In this zone, cotton-
woodsi can be found along the stream bottoms along with
alder, birch, and willow (riparian vegetation). However,
therei is limited riparian vegetation along California Gulch
and j.ts tributaries. The limited riparian habitats are
found near the Malta Gulch confluence (Topielec, 1977).
DE/CALGU6/007
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Inquiries with the Colorado Natural Areas Program (O'Kane,
1986) noted that Lake County has two threatened or exemplary
plant communities: Porter Needlegrass and Alpine braya.
However, these species are not located in the site study
area.
WILDLIFE
There is little specific information on wildlife within the
site study area. The wildlife found within the study area
should be similar to those found in the general Leadville
area. However# the disturbed landscape and level of past
and present human activity in. both Leadville and the Cali-
fornia Gulch area may tend to minimize the number and
diversity of wildlife within the site.
The mountain forests and meadows elsewhere in Lake County
support large numbers of deer and elk. Much of the area
along the Arkansas River valley is important winter range
for deer and elk. Elk calving- grounds are found around Twin
Lakes, which are several miles downstream from Leadville.
Black bear# bighorn sheep, and Rocky Mountain goats are also
found in the area (Topielec, 1977).
Numerous smaller animals are present# including furbearers
such as beaver# mink# racoon# weasels# and muskrats; small
game such as cottontails and jackrabbits; and rodents such
as mice# moles# chipmunks, squirrels, and marmots. Coyotes
are very common in the Upper Arkansas Basin; bobcat, red
fox, and mountain, lions are occasionally seen. Pika are
common on the talus slopes near timberline (Topielec, 1977).
Waterfowl, such as mallards, teal, and coots, use the marsh-
lands along the Arkansas River as resting areas. Turquoise
Lake, west of Leadville, may support a breeding population
of ducks. American kestrel (Sparrow hawk) are common in the
DE/CALGU6/007
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area, and there ara a few nesting goshawks and golden eagles
In the mountains along the river valleys. Bald eagles, red-
tailed hawks, and ferruginous hawks are sometimes present as
transients. There is a wide variety of small birds in the
Le2idville area. Upland game birds are not common (Topielec,
1977).
O'Kane (1986) stated that the lynx had been noted to exist
in the study area. The tiny hawksbeard was also noted to
exist in Lake County, but not specifically in the study area.
FISiH AND BENTHIC MACRO INVERTEBRATES
Tho Arkansas River, upstream of Leadville (Tennessee Creek
and East Fork), supports a fair population of brown and brook
trout; however, most fish are small with an average length
of 180 millimeters (mm) (LaBounty, 1975). The bottom-dwelling
macroinvertebrates include a variety of mayflies, stoneflies,
and caddisflies.
California Gulch waters do not support any fish because of
heavy metal concentrations and high turbidities. Reports
indicate that no fish and only a few limited species of aquatic
invertebrates are found in the Arkansas River for 1.5 miles
downstream of the confluence with California Gulch
(LaBounty, 1975, and McLaughlin, 1981).
Some stoneflies and mostly diptera larvae, being relatively
tolerant of heavy metals, were collected in another inves-
tigation all .along the Arkansas River. Genera of mayflies
and caddisflies, being sensitive to lower water quality,
with few exceptions, were not found immediately below the
confluence of California Gulch and the Arkansas River
(LaBounty, 1975, and Roline, 1981) .
Di:/CALGU6/007
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Studies by the Colorado Division of Wildlife have shown a
marked decrease in the diversity of aquatic organisms in the
Arkansas River immediately below California Gulch. Diversity
increases within a few miles because tributaries, such as
Lake Fork and Halfmoon Creek, discharge high-quality water
into the Arkansas River. Trout populations increase down-
river of these tributaries and include brown, brook, and
rainbow trout. Analyses of brown trout livers for heavy
metals (collected downriver of California Gulch) indicated
that these fish had been chronically exposed to high levels
of metals and had bioaccumulated copper and zinc (Roline,
1981).
CLIMATE
The climate in the California Gulch study area is considered
to be normal for the mountainous area* of central Colorado.
The severe local topographic features strongly influence
local climatic variations in Lake County. The City of Lead-
ville is at an elevation of approximately 10,000 feet MSL.
Weather conditions are recorded at the National Weather Ser-
vice '3 Leadville airport station located 2 miles southwest
of Leadville. Elevation of the Leadville station is
9,938 feet MSL.
The normal temperature extremes range from 86° F to -30° F,
with the average minimum temperature being 21.9° F (Topielec,
1977). The average frost-free season is 79 days. The wind
is predominately from the northwest and ranges from calm to
30 miles per hour (mph) (Gilgulin, 198S). No wind rose is
available.
Average annual precipitation is 18 inches. July and August
record the most precipitation, while the months of lowest
precipitation are December and January (USDA, SCS, 1965).
Summertime precipitation is usually associated with convect.ve
DE/CALGU6/007
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showiora (Topielec, 1977) . Annual snowfall depths for moun-
tain:! in the area are between 200 and 300 inches. During
winter months, the depth of snow on the ground in Leadville
is commonly 6 inches (Gilgulin, 1985) .
Precipitation data were extracted from National Oceanic and
Atmospheric Administration (NOAA) clisatological data records
for Colorado~ The monthly precipitation data for the study
period and 10-year average (1975 through 1985) at the Lead-
ville Weather Reporting Station are tabulated in Table 2-2
and graphed in Figure 2-7. The annual peak snowmelt usually
occurs in June and is depicted in the hydrograph for the
middle flume presented in the stream flow section of Appen-
dix H.
labl* >2
Kmmm ua 10-ma avbugz pmcxmtxxov
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D«eaator
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April
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July
Augaat:
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1983
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1984
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1993
Annual"
10 Tear
AnouaT
Man eft Cuanlatiy Monet! Cuulatlv Meatft Cuilatly Montb Cuanlatlv
10.08
0.28
0.81
1.28
1.39
2.32
3.76
5.94.
6.31
7.33
9.24
9.81
10.08
16.43
1.18
<>.69
4.86
5.13
6.11
6.90
7.37
3.29
10.69
14.94
13.56
16.43
Hoc*i Miimura—ta prw«nca4 Id iacbaa.
Sourcm national ftaacOir Surlei
13.S3
0.40
0.99
1.57
1.69
3.46
5.67
6.82
7.44
9.89
10.31
12.42
13.33
16.32
1.06
2.43
3.85
5.20
6.63
3.33
9.53
10.60
12.58
14.44
13.66
16.32
DE/CALGU6/007
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PHECJPfTATICN
MONTHLY
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2-23

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Limited air quality information for the Leadville area is
aval J. able from' the Colorado Department of Health (COH) for
suspended particulates and lead. These data will be evalu-
ated during the Phase II RI.
LAND USE
Approximately 2/3 o£ the land in LaJce County is federally
owned; the study area is principally privately-owned land.
Most of the- federal land is within the San Isabel National
Forant, with the Bureau of Land Management (BLM) overseeing
most of the remaining land. Land use in the California Gulch
area is predominantly mining, commercial, and residential.
Alon
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since approximately 1920. No official growth projections or
income levels.of the population are available.
Table 2-3
LAKE COUNTY POPULATION DATA
AND CURRENT ESTIMATED POPULATION
Area
1960
1970
1975
1980
1985a
Lakei County
Leaclville
Unincorporated
7,101 8,282 9,445 8830 6,600
4,008 4,314 4,745 4356 3,800
3,093 3,968 4,700 4474 2,800
aShroyer estimate, 1986.
Source: Topielec, 1977.
Leadiville has a current population of about 3,800, with an
approximate age distribution a * follows (Shroyer, 1986):
o	0-16 years—25 percent
o	17-21 years—15 percent
o	22-41 years—25 percent
o	42-60 years—15 percent
o	60-100 years~20 percent
WATilR SUPPLY
The Parkville Water District supplies water to Leadville,
Strlngtown, Silver Hills, and Matchless and has 1,807 paying
cust.omers (Herald Democrat, 1985). In 1979, this number was
1,909 (Shroyer, 1986), which corroborates the declining area
population. The district's sources of water include the
Canterbury Tunnel, the Elkhorn Shaft, wells, and the Big
Evans Gulch Reservoir. There is also a report of a diversion
from Iowa Gulch, but this has not been fully substantiated.
DE/CALGU6/007
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Th® Parkville water system has a filter/chlorination treat-
ment system with a capacity of 1.6 million gallons per day
(mgd) and treated storage capacity of 1.5 mgd. Water samp-
les are taken monthly and have routinely met water quality
standards.
The northwestern boundary of the Parkville system includes
Silver Hills subdivision, Matchless Estates subdivision, and
West Park subdivision. Tha northern boundary is at the junc-
tion of U.S. Highways 24 and. 91. The eastern boundary
extends the Leadville city limits. The southern boundary
extends from Apache Energy and Minerals Company's tailings
impoundment to Stringtown (including the Colorado Mountain
College). The southwestern boundary is known as the
"dividing line" road that runs north from U.S. Highway 24 at
the junction with Colorado Mountain College road. This
includes St. Vincents Hospital and the Leadville schools.
Outside of the Parkville Water Service Area, well water is
used for domestic supplies, irrigation, commercial, munici-
pal, and industrial uses. There are €24 wells in Lake County,
based on well permitting information. Approximately 35 of
these existing wells are located in the study area (see Sec-
tion 3, Figure 3-3). A number of people in Stringtown and
the lower part of California Gulch have domestic wells. The
current usage of these wells is presented in Section 3.
Within the study area, this well water primarily comes from
the shallow groundwater system in the upper terrace gravels.
SITE HISTORY
Mining and mining-related activities have occurred in the
Leadville area since the mid-18001s. Early mining-related
activities at Leadville included the following: placer oper-
ations; lode mining of silver and lead ores? and lode mining
DE/CALGU6/007
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of sine ores (Emmons, 1927) . Hundreds of mines, more than
40 simelters, -and several placer operations contributed to
the economy and environmental problems in Leadville. Emmons
(192 7) identified 1,329 mine shafts, 155 tunnels, and
1,62 8 prospect holes in the Leadville District having an
estimated aggregate length of 75 miles. In the surrounding
area, Behre (1953) identified an additional 1,800 openings
of various types.
Environmental degradation occurred from mining-related ac-
tivities, including the following:
o Discharge of mineral processing wastes and tail-
ings; smelter flume emissions and dust? and dis-
posal of smelter slags. Mining-related wastes
were disposed of on the land, in surface waters,
and in. the atmosphere of the Leadville area. By
1881 r 14 smelters were operating at the sam* time
(Ubbelohde, Benson,, fr Smith, 1972).
o Discharge of mine waters from dewatering pumps and
tunnels into surface waters, resulting in decreased
water quality. By the 1890's, as much as 15 mgd
were pumped from the mines (Emmons, 1927).
o Placer and hydraulic mining disturbances that
stripped surface soils and alluvium. (Digerness,
1977) .
o Construction of the Yak Tunnel to dewater mines in
the Iron Hill, Breece Hill, Ibex, and Resurrection
areas. By 1923, the Tunnel produced a flow of
15,000 gallons per minute (gpm) (Labounty, et al.,
1975) .
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o Local deforestation for fueling the smelters, con-
structing diversion flumes, and supplying under-
ground mine workings. This removal of vegetation
increased runoff rates and contributed to increased
erosion and sediment transport (Emmons, et al.,
1927).
Additional information on Leadville can be found in FranJc
Hall's multi-volume set, History off the State of Colorado,
and D. L. and J. H. Griswold's The Carbonate Camp Called
Leadville. Additional details on the history of the Yak
Tunnel are presented in the following section.
YAK TUNNEL HISTORY
Historically, the Yak Tunnel was one of several drainage
tunnels constructed to dewater mines in the Leadville District,
Started by A. A. Blow in 1895, the Yak Tunnel was targeted
to drain the Iron Hill area (McLaughlin, 1981). Previous
studies have indicated that the Yak Tunnel is the major con-
tributor of acid and metals to the California Gulch drainage
system (McLaughlin, 1981; LaBounty, et al., 1975; and Moran
and Wentz, 1974).
With the portal at an elevation of 10,330 feet MSL, the Yak
Tunnel was driven eastward to penetrate the Iron-Mikado
fault system. The venture proved so successful that the
tunnel was extended at various times, successively pene-
trating the Breece Hill, Ibex, and Resurrection areas. In
1912, it was terminated at the Resurrection No. 2 Mine. The
total length, including principal laterals, is over 4 miles
(McLaughlin, 1981) . Figure 2-9 presents the major mining
DE/CALGU6/007
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areas in the Leadville Mining District, the faults of
importance, and the tunnels draining the area.
A surge of mining activity in the early 1920's in the Car-
bonate Hill and Iron Hill areas sparked new interest in
using the Yak Tunnel for dewatering purposes. In May 1923,
the Yak Tunnel was again extended, and produced a flow of
15,000 gpa (LaBounty, et al., 1975). This flow rate had
diminished to approximately 8,700 gpm by June of 1924. By
that time, the tunnel drained a complex area of massive
sulfide and carbonate mines through a maze of underground
mine workings*
Determination of all underground connections is impossible,
but many of the major areas such as the White Cap, Ibex,
Resurrection, and Irene Mine groups are known (McLaughlin,
1981) • According to previous studies (URS/Ken R. White
Company, 1974), drifts extend from the Yak Tunnel to the
Horseshoe Mine, Ruby Mine, North Mike Mine, South Mike Mine,
Ibex No. 4 Mine, Little Vlnnie Mine, Resurrection No. 1 Mine,
and the Black Cloud Mine through the Irene No. Z Mine. Other
nearby mines also drain to the Yak Tunnel through intercon-
nections with these and other mines, or through faults, cracks,
and fissures in the rock surrounding the tunnel. Lower por-
tions of many of the mines described above are at elevations
lower than the Yak Tunnel and were pumped during mining.
In 1983 and 1985, surge events occurred at the Yak Tunnel.
Surge events are short-duration, high-flow events from the
sudden release of impounded water within the tunnel or its
laterals. When the tunnel was maintained as part of ongoing
mining operations, surge events did not occur. Once main-
tenance stopped, the tunnel likely began to decay. Roof
rock and timbers have probably collapsed, creating water
DE/CALGU6/007
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impoundments. When the hydraulic pressure becomes high
enough# it bursts the impoundment and a surge occurs. Flow
rates and volumes of a surge event are not predictable; the
rates and volumes are determined by the location and size of
the water impoundments in the tunnel.
The 1983 event was caused by ASARCO personnel removing col-
lapsed timbers; the 1985 event was likely related to lack of
tunnel maintenance. Plate 9 shows some of the results of
the 1985 surge event. The event in 1985 lasted about
15 hours, and had. a release of approximately 1,000,000 gal-
lons with an estimated instantaneous peak flow rate of 10 cfs.
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GROUNDWATER FLOW
Groundwater flow depends upon a complex, balanced mixture of
recharge, hydraulic gradient, physical aquifer characteris-
tics, and discharge. The flow direction and hydraulic gra-
dient are typically defined by water levels. Groundwater
levels were measured in accessible wells in conjunction with
the water quality sampling programs. Water level data are
shown in Appendix N where they have been both tabulated and
contoured to show the water table during each sampling
event.
The basic physical aquifer characteristics are the trans-
missivity (field permeability times saturated thickness) and
storativity (the volume of water taken into or released from
storage in the aquifer). These characteristics were deter-
mined for two different depth intervals in the California
Gulch alluvial system to determine the amount of groundwater
moving from California Gulch alluvium into the Arkansas
River alluvium. The two pump test results are shown in
Appendix N and described in the pump test section of the
report.
Water Levels
The water level data for the wells in the California Gulch
high terrace gravels (Emmons, et al., 1927) indicate that
groundwater level essentially follows the topography.
Recharge is from snowmelt, rainfall, and California Gulch
surface water percolating into the alluvial groundwater sys-
tem. Three well nests were completed to varying depths in
the high terrace gravels: in the tailings area (NW-5, NW-5A,
and NW-5B); below the tailings area, but above Jacktown (NW-6
and NW-6A); and above the confluence with the Arkansas River
alluvium (NW-13 and NW-13A). Water levels measured during
the RI investigation indicate that groundwater moves to deeper
DE/CALGU8/022
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levels at all three locations. There are no significant
upw.ird (artesian) heads indicated by the water level measure-
men-s .
Groundwater levels measured on both the NW and EW wells along
California Gulch indicate as much as 14 feet of fluctuation
in .'Shallow wells. The nested well set at NW-5, NW-5A, and
NW-'iB has perforated depth intervals of 15 to 35, 48 to 108,
and 160 to 220 feet. The water level fluctuation ranges
from: 10 feet in the shallowest well to 5.62 feet in the
intermediate well and to 0.25 foot in the deepest well.
This pattern of fluctuation in the groundwater, with the
shallowest wells having the highest fluctuation and the fluc-
tuation declining with depth, is common in alluvial systems
with recharge moving from the surface downward. The recharge
reaches its highest level between May and June, based on the
water level measurements. The water levels then decline for
the rest of the year, as the water drains from the California
Gulch alluvial system.
A major source of year-round recharge to the California Gulch
alluvium is the snowmelt that percolates from the mountain
surfaces, through the mine workings, to the YaX Tunnel. The
Tunnel drains as a point discharge to the California Gulch
surface water system that, in turn, recharges the alluvial
groundwater system. The changes in groundwater level suggest
that the amount of recharge decreases with depth. The upper
10 feet of the groundwater system at the nested well NW-5
group, is recharged and drained from the alluvial system
during the year and is replenished by recharge in the next
sno'-mielt period. By contrast, less than 1 foot of groundwater
drained from the deepest well in the nest over the same time
per lod.
DE/CALGU8/022
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Piezometer Tube Program
To define the amount of groundwater flowing through various
levels of the California Gulch alluvial system per unit
time, however, requires determining the hydraulic gradient
and developing the basic physical characteristics that are
determined by pump testing. Surface water flow measurements
noted several segments of the Gulch that were losing flow to
the groundwater (losing stream). To verify this intimate
connection of surface water with the shallow zone (up to
10 feet) of the alluvium, a piezometer tube program was
implemented.
Hand-driven piezometer devices are traditionally used to
examine groundwater/surface water interactions in situations
where shallow groundwater may be discharging to a lake or
stream. Lee and Cherry (1978) present a detailed descrip-
tion of the design of such devices and their role in examin-
ing groundwater hydraulic potential beneath lake or streambeds
of interest.
The use of piezometers in groundwater/surface water inter-
action studies involves observing the hydraulic head poten-
tials where a stream is either gaining flow or losing flow
as a result of interaction with the underlying shallow
groundwater body. Hydraulic head will decrease with depth
below the stream under conditions where the stream is losing
flow to the groundwater system, and will increase with depth
under conditions where the groundwater system is discharging
to the stream. The water levels observed in piezometers
completed at different depths beneath a stream bed are an
indication of the hydraulic head at that particular depth.
By comparing water levels in piezometers completed at dif-
ferent depths to one another and to stream level, a rapid
assessment as to whether the stream is gaining flow (upward
DE/CALGU8/0 22
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hydraulic gradient), or losing flow (downward hydraulic
gradient) can be made.
Twenty-one piezometer stations were installed within or imme-
diately adjacent to the California Gulch stream channel in
November 1984. The section of stream under study included
the approximately 5-mile segment between the Yak Tunnel and
the Arkansas River confluence. The stations consisted of
either: one piezometer (the water levels of which could be
compared to stream level); or 2 to 3 piezometers which could
allow comparisons of water levels to one another as well as
to stream level. The piezometers consisted of 5- to 10-foot
lengths of 3/4-inch iron pipe containing a short (3- to 5-inch)
section of slotted surface and drive point. The piezometers
were hand-driven into place to either a desired depth or to
refusal. The piezometers were checked for openness with a
response test by filling with water and allowing the water
level to drop to a stable level- Piezometers which were not
open or operating successfully were removed and either redriven
or replaced. A full-suite of water level measurements were
obtained from the piezometers on November 20, 1984, and an
assessment was made regarding gaining and losing stream con-
ditions in existence at that time. The results show that
the California Gulch stream channel is in hydrologic connec-
tion with shallow groundwater and that there are several
major transition sections where the stream goes from gaining
to losing conditions.
Figure 4-6 shows the locations of the piezometer stations
and identifies whether gaining or losing conditions were
observed on the November 20, 1984 date of study. The results
shew that there are several stream segments that are re-
ceiving groundwater discharge (gaining) as evidenced by the
streaxn-groundwater hydraulic conditions observed on the
November 20, 1984 test date. Other segments of the stream
were observed to be losing flow to the shallow groundwater
regime beneath the stream channel.
DE/CALGU3/0 22
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Sulfate is closely associated with the oxidation of sulfides.
Sulfate, like specific conductivity, decreases with the depth.
The mean sulfate concentration in the upper 25 feet of the
California Gulch alluvium ranges from less than 100 mg/1 to
more than 1,000 mg/1. The secondary MCL is 250 mg/1. Many
of the private (EW) and new wells (NW) in the California
Gulch alluvium exceed this concentration, particularly those
completed in the upper 50 feet of the alluvium.
Manganese, zinc, and cadmium are trace metals that are easily
mobile in the groundwater system; iron and lead are not very
mobile in oxidized, sulfate-rich groundwater. Manganese,
zinc, and cadmium were used to determine the extent of verti-
cal contamination in the California Gulch alluvial groundwater
system resulting from the recharge from the surface water.
Manganese has a secondary MCL of 5 0 ug/1. Manganese concen-
trations for surface water at stations SW-4, SW-7, SW-9, and
SW-12 ranged from 9,330 ug/1 at SW-12 to 24/530 ug/1 at SW-9.
Manganese concentrations in groundwater in the upper 20 feet
of the alluvium ranged from below the standard to as much as
15,000 ug/1- In the 20- to 50-foot depth range, manganese
concentrations decrease to less than 4,000 ug/1; below 50-foot
depths, manganese generally meets the standard.
Zinc has a secondary MCL of 5,000 ug/1. The zinc concentra-
tions measured from the above surface water stations range
from 25,000 ug/1 at SW-12 to 62,500 ug/1 at SW-4. The zinc
content decreases in a downstream order; it is highest below
the Yak Tunnel discharge and lowest at the confluence with
the Arkansas River. Zinc concentrations in the groundwater
are highest in the upper 25 feet of the alluvium ranging
from below the standard to as much as 35,000 ug/1. Zinc
concentrations in the 25- to 50-foot depth range from below
standard to as much as 1,000 ug/1- 3elow an approximate
DE/CALGU 8/022
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50-foot depth, the typical zinc concentration is less than
500 ug/1.
Cadm;.um has a primary MCL of 10 ug/1. Cadmium concentrations
dissolved in the surface water of the four comparative surface
water stations mentioned previously ranged from 104 ug/1 at
SW-i;> to 267 ug/1 at SW-4. Cadmium/ like zinc, generally
decreases with distance below the Yak Tunnel discharge.
Like manganese and zinc, the upper 25 feet of the California
Gulch alluvium contains the highest concentration of cadmium.
Concentrations range from below the drinking water standard
to aj; much as 100 ug/1. Mean cadmium concentrations decrease
to less than 10 ug/1 in the 25- to 50-foot depth ranges and
to less than 5 ug/1 in deeper parts of the groundwater system.
The upper 25 to 50 feet of the California Gulch groundwater
system contain metals in concentrations in excess of drink-
ing water standards. These excessive concentrations result
in part from infiltration of California Gulch surface water.
Existing wells that exceed primary MCL's are noted as
follows:
o Chase Shop, EW-12. Cadmium ranged between 65 and
116 ug/1 for all five sampling events.
o Chase House, EW-13. Cyanide exceeded 200 ug/1 on
two occasions (204 ug/1 in June 85 and 203 ug/1 in
September). Cyanide routinely appears at EW-12,
EW-13, and occasionally at EW-29. To date, the
source of the contamination has not been located.
Several additional monitor wells would be required
to locate the source, but until cyanide levels
dramatically increase, no additional work is
anticipated.
DE/CALGU8/022
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o Mestas/ EW-14. A cadmium concentration in June 85
of 15 ug/1 was noted. Based on this plus additional
sampling data, EPA took action in May 1986 to con-
nect the Mestas household to the Parkville public
water system.
o Shoeber, EW-19. Cadmium ranged from 28 to 1124 ug/1
over all five sampling events.
o Gruden, EW-26. Lead at 296 ug/1 was noted during
the November 19 84 sampling episode. This value is
suspect since lead was not detected for the four
subsequent sampling events.
o Meyer, EW-32 (cribbed)„ Cadmium ranged from 10 to
15 ug/1 on four of the five sampling events.
These wells, and others, exceeded secondary MCL's on several
occasions. These data are presented in Tables 4-20 through
4-24.
Groundwater and Tailings Impoundments
Six new monitoring wells (NW) were installed downgradient of
tailings impoundments: one below the Oregon Gulch tailings
impoundment (NW-4) , one b.elow the semi-active Leadville Corp-
oration tailings impoundment near Stringtown (NW-10), and
four below the three impoundments on the California Gulch
mainstem (NW-3, NW-5, NW-5A, and NW-5B). Well water below
the tributary impoundments contains some of the highest con-
centrations of dissolved metals of any samples collected on
the site. In comparison, well water from below the California
Gulch impoundments sites contained several of the lowest
concentrations of dissolved metals. Table 4-25 presents
mean dissolved concentrations of sulfate, zinc, manganese,
and cadmium in these six groundwater monitoring wells.
DE/CALGU8/022
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Table 4-25
MEAN DISSOLVED CONCENTRATIONS OF SULFATE AND SELECTED
METALS IN NEW MONITORING WELLS BELOW SITE TAILINGS
IMPOUNDMENTS FOR ALL SAMPLING EVENTS
Screened 	Mean Dissolved Concentration	
Monitoring Interval Sulfate	Zinc Manganese Cadmium
Well	(ft BGL) (uq/1)	(uq/1)	(uq/1) (ug/1)
NW--4	5-45	17,100,000	676,000	1, 396,000	906
NW-10	10-50	240,000	8,240	3,700 54
NW-3	26-76	61,000	149	99 U
NW--5	48-103	1,253,000	524	211 U
NW-5A	15-25	3,100,000	574	16 U
NW--5B	160-220	529,000	46	99 U
Note: U=Undetected.
BGL=Below Ground Level
Monitoring well NW-4, below the Oregon Gulch impoundment,
had metal and sulfate concentrations much higher than the
mean dissolved constituents for the Yak Tunnel discharge to
California Gulch surface water. The groundwater moving
downgradient from the Oregon Gulch impoundment does not seem
to influence California Gulch surface water quality between
the iTW-5 well nest and the NW-6 well nest. Groundwater
quality improves (decreases in metals) in the mainstem of
the Gulch between NW-2 and NW-6A.
Monitoring well NW-10, downgradient of the semi-active tail-
ings impoundment (now owned by Leadville Corporation), on a
tributary to Malta Gulch, had metal concentrations much lower
than the groundwater concentration in well NW-4. The dif-
ference between the two sets of values is due to either
dilucion by groundwater or because of low quantities of
sulfides in the impoundments. Compared to NW-4, the dis-
solved zinc to sulfate ratio is essentially the same, and
the cadmium to zinc ratio is within one order of magnitude.
DE/C.\LGU8/022
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The three tailings impoundments in the California Gulch main-
stem do not appear to significantly affect the water quality
of the less than 30-foot-depth groundwater system in the
California Gulch alluvium. Comparison of groundwater chemis-
try in monitoring wells NW-2 (Upper California Gulch) and
NW-6A (below tailings impoundments) demonstrates the quality
in the 5- to 30-foot interval (Table 4-26).
Table 4-26
MEAN DISSOLVED CONCENTRATIONS OF SULFATE AND
SELECTED METALS FROM ABOVE AND BELOW TAILINGS
IMPOUNDMENTS ON CALIFORNIA GULCH
Sample
Screened
Mean
Dissolved
Concentration
Site
Interval
Sulfate
Zinc
Manganese
Cadmium
Number
(ft BGL)
(uq/1)
(uq/1)
(uq/1)
(uq/1)
NW-2
8-28
736,000
74,700
30,400
404
SW-4
NA
794,000
62,500
19,100
267
SW-7
NA
768,000
56,120
24,300
230
NW-6A
9-29
618,000
14,800
4,020
53
Note: NA
= Not Applicable (Surface Water
Stations)

BGL = Below Ground Level
Well NW-2, in upper California Gulch, indicates groundwater
quality above the tailings impoundments. However, this well
may reflect influences of the Yak Tunnel discharge. Well
NW-6A is approximately half a mile below the nearest tailing
impoundment and approximately 1,500 feet downgradient of the
Oregon Gulch confluence with California Gulch. However,
according to data presented in Figure 4-6, California Gulch
is a gaining stream in this half-mile stretch. Near NW-6A,
the Gulch becomes a losing stream. Thus, leachate from the
tailings impoundments could enter the Gulch and be trans-
ported downstream to the area of NW-6A. Here, they could
enter the near surface groundwater system.
DE/CALGU8/0 22
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Sulfate, zinc, manganese, and cadmium all decrease in the
shallow groundwater from the Yak Tunnel area to below the
tailings impoundments on California Gulch. Sulfate shows
little change in concentration, probably because it is near
the minimum concentration for groundwater in the mineralized
area. Zinc, cadmium, and manganese concentrations decrease
by more than a factor of 5. A water chemistry comparison
with the two surface water sites, SW-4 and SW-7 (located
between the Apache Energy and Minerals Company's impoundment
and Oregon Gulch), indicate that the surface water sulfate,
zinc, and cadmium also decrease over this reach; however,
manganese increases.
The cadmium to zinc ratios of the groundwater are reasonably
constant, and strongly correlate with the cadmium to zinc
ratios of surface water at both SW-4 and SW-7. This, plus
the increase in concentration of manganese in the surface
water, confirms that, in the tailings impoundment area on
California Gulch, shallow groundwater (to 30 feet) is moving
into the surface water. The subsurface area covered by the
tailings impoundments is structurally complex. This includes
several ma]or fault zones that mark the beginning of the
major alluvial system of lower California Gulch.
Groundwater and Slag Piles
Mcnitoring well NW-17 is adjacent to and upgradient from the
major slag pile on lower California Gulch; well NW-8 is
dowr.gradient of the pile. A spring, SW-10, is adjacent to
and dcwngradient of the slag, but upgradient of well NW-3.
A comparison of the mean dissolved concentrations for
sulfate and other metals for these three sampling sites is
shown m Table 4-27. Results, in the order MVJ-17, SVJ-1C,
jrw-3 indicated: (1) zinc increased by almost two orders ci
magnitude (31 and 47 times); (2) manganese concentrations
essentially tripled; and (3) cadmium concentrations ccublad.
The slag apparently has an impact on the metal content m
the groundwater.
DE/CALGU3/0 22
4-59

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Table 4-27
MEAN DISSOLVED CONCENTRATION OF SULFATE AND SELECTED
METALS IN NEW MONITORING WELLS AND SURFACE WATER STATIONS
BELOW STRINGTOWN SLAG PILE FOR ALL SAMPLING EVENTS
Screened 	Mean Dissolved Concentration	
Monitoring Interval Sulfate Zinc Manganese Cadmium
Well	(ft BGL) (uq/1)	(uq/1)	(uq/1) (vq/1)
NW-8	16-53	969,000 21,175	834	76
NW-17	60-100 1,393,000	443	317	39
SW-10	NA	1,114,000 3 6/114	1,172	54
Note: NA=Not Applicable (Surface Water Station)
BGL=Below Ground Level
DATA INTERPRETATION
STATISTICS
Data management was an important tool in regard to data inter-
pretation. Computer-assisted data reduction was made an
integral part of this investigation to assure quality and
efficiency of effort. As a first step to sorting and corre-
lation of data, quality-audited laboratory analytical
results were subjected to statistical analysis. A detailed
description of the process is found in the Statistics and
Water Chemistry Correlation sections in tie IA.
The statistical analyses indicated that, in spite of the
large range in concentration (variance) of most ions,
especially the metals, many of the ions are strongly inter-
related. Results of the correlation analysis (a measure of
the strength of a relationship between two variables) between
the dissolved ions suggested that the definition of a few
ions would essentially define the behavior of many ions.
DE/CALGU8/022
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For example, iron is strongly correlated with zinc and copper.
This indicates that the oxidation of the sulfides of iron
(pyrite), zinc (sphalerite), and copper (chalcopyrite) essen-
tially occurs at the same time and place. Therefore, any
one of these elements could be used to define the general
geochemical characteristics of the others. Zinc and cadmium
are strongly correlated, suggesting that dissolved cadmium
is probably coming from the oxidation of the zinc sulfide
(sphalerite). Sulfate, resulting from the oxidation from
the sulfides, is very strongly related to total dissolved
solids, iron, zinc, and copper.
Surface Water/Groundwater Correlation
The geochemical weathering process (oxidation of sulfides to
mobilize metals found in tailings, slags, and other mine
wastes) results in metals contamination to the surface water
and groundwater in the study area. Analysis of chemical
profiles along the Gulch for surface water and alluvial
groundwater indicates potential sources of contamination,
i.e., the Yak Tunnel, tailings impoundments, Starr Ditch,
and ar'2as containing slags; see Figures 4-7 through 4-9. In
addition, changes in seasonal surface flow and corresponding
changes in the shallow zone of the alluvial groundwater
levels indicate an intimate connection to each other. Pump
tests further established a limited vertical connection be-
tween -:he upper and lower levels of the alluvial (high ter-
race g::avel) groundwater system. Metal contamination levels
typically decreased with depth into the alluvium. Results
of the piezometer pipe program supported the surface water/
shallow alluvium groundwater connection, and the postulaticn
that the mainstem of the Gulch is acting as a single conduit
or pipeline along which contaminated waters are moving to
the Arkansas River. Pump tests and field measurements also
indicated no significant groundwater contribution from the
Gulch alluvium directly to the Arkansas River.
DE/CALGU8/022
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SW-4
SW-7
SW-3
NW13A
.IU III HJ
NW-6A
NW-ft
SW-12
NW-5
i
O IjJ U HJI-JliWAl £11
LI Mllll ACL WAltfi
T	•	1
4	0a
API'IIOXIMAIE DISTANCE pHOM CONFLUENCE (1000 i II)
r
10	12
FIGURE 4-7
DISSOLVED ZINC CONCENTRATIONS
CALIFORNIA GULCH (11

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Mining Waste NPL Site Summary Report
Carson River
Lyon and Churchill Counties, Nevada
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-0025, Work Assignment Number 20.
A previous draft of this report was reviewed by Sean Hogan of EPA
Region IX [(415) 744-2233], the Remedial Project Manager for the
site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
CARSON RIVER
LYON AND CHURCHILL COUNTIES, NEVADA
INTRODUCTION
This Site Summary Report for the Carson River site is one of a series of reports on mining sites on
the National Priorities List (NPL). The reports have been prepared to support EPA's mining program
activities. In general, these reports summarize types of environmental damages and associated mining
waste management practices at sites on (or proposed for) the NPL as of February 11, 1991 (56
Federal Register 5598). This summary report is based on information obtained from EPA files and
reports and a review by the EPA Region IX Remedial Project Manager for the site, Sean Hogan.
SITE OVERVIEW
The Carson River Superfimd Site is a 50-mile stretch of the Carson River located in the Nevada
counties of Lyon and Churchill. The site begins in the Brunswick Canyon between Carson City and
Dayton and extends downstream through the Lahontan Reservoir (see Figure 1) (Reference 1, page
2). This portion of the Carson River has been contaminated by mercury from the historic operations
of approximately 100 gold and silver ore processing mills. These mills lost an estimated 12 to 18
million pounds of mercury to either mill tailings or direct discharges to the Carson River during their
active life in the late 1800's. The Carson River site was proposed for the NPL in October 1989 and
listed in August 1990. Mercury is the contaminant of concern.
The Carson River Basin is a large recreational and commercial fishery resource. The Carson River
Basin comprises five hydrographic areas, which include Carson Valley, Eagle Valley, Dayton Valley,
Churchill Valley, and the Carson Desert, totalling about 3,365 square miles. The East and West
Forks of the Carson River arise in the Eastern Sierra, flow through an intricate irrigation system
within the Carson Valley and then coalesce to form the main stream of the Carson River. The river
continues north through the Carson Valley, skirting the east side of Eagle Valley, then turns northeast
to pass through Brunswick Canyon. Continuing east through Dayton Valley, the river flows into
Churchill Valley, site of the Lahontan Reservoir (the main water storage reservoir of the Newlands
Irrigation Project). Below Lahontan Dam, a complex system of canals and drains facilitate irrigation
in the Carson Desert. The river and irrigation return flow ultimately flows northeast to the Stillwater
National Wildlife Refuge and the Carson Sink, or south to Carson Lake.
1

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Carson River

) Sevenmtfe Canyon
i / (lOmJlaues)
Virginia Clfy 1
(20 mil aiiea) Y

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. (iSmtfdlea) S*
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FIGURE 1. CARSON RIVER SITE MAP
2

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Mining Waste NPL Site Summary Report
An estimated 700,000 people use the river system annually for recreation, fishing, and irrigation
purposes. Approximately 1,200 acres of food and forage crops are irrigated by water from a 50-mile
stretch of the Carson River in the NPL site. The Carson River is not currently used for drinking
water. The Dayton Valley Estates Water Company services 139 homes with water from an
underground aquifer. The wells are 1.25 miles from mercury-contaminated tailings piles (Reference
1, Sample Analysis Section, page 4). In the Dayton Valley area, at least 226 households not served
by a public water supply are within 3 miles of either the Carson River or a mercury-contaminated
tailings pile At least 30 of these homes are within 2,000 feet of either the Carson River or a
contaminated tailings pile (Reference 1, Sample Analysis Section, page 4).
The Carson River site consists of sediments in the Carson River and tailing piles associated with
historic milling operations along the River. Mercury-contaminated tailings piles have been found 5
miles up Brunswick Canyon, 3 miles up Six Mile Canyon, and within the Carson Plains. Areas near
the Comstock Lode where extensive mining occurred, such as in Gold Canyon, may also be major
potential sources of mercury-contaminated mine tailing piles. Annual rains transport mercury from
the tailing piles to the Carson River and floods in 1986 washed "mercury rich" sediments from the
Carson Plains into the Carson River (Reference 1, Sample Analysis Section, pages 1 through 5).
The Nevada Department of Environmental Protection (NDEP) sampled one tailings pile located near
Six Mile Canyon Creek Drainage in May 1986. The tailings pile was estimated to be approximately
100 feet long, 15 feet wide, with an average height of 4 feet, and a volume estimated to be 222 cubic
yards. The pile contained mercury at concentrations of 443 parts per million (ppm). For Hazard
Ranking System purposes, only this tailings pile was sampled to define the waste quantity for the
Carson River Superfund Site (Reference 1, pages 6 and 7). According to the NDEP, this tailings pile
is one of hundreds of mercury-contaminated tailings piles known to exist in Brunswick and Six Mile
Canyons. Due to the large number of known tailing piles in Brunswick and Six Mile Canyons (and
possibly in Gold Canyon) and due to the large amount of mercury lost during the milling process, the
waste quantity estimated from the one sampled tailings pile "is expected to vastly under-represent the
total waste quantity at the site" (Reference 1, page 6).
According to EPA Region IX, a Remedial Investigation and Feasibility Study for the Carson River
site was initiated in September 1990. EPA's immediate priority is to analyze the options for the
stabilization and containment of the tailings piles (Reference 3, page 71). In addition, EPA is
searching historic mining claims and land ownership titles for Potential Responsible Parties (PRPs)
(Reference 3, page 58).
3

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Carson River
OPERATING HISTORY
Due to the historical nature of the mining operations which resulted in the mercury contamination,
there is little information available on the operating history of the site. During the late 1880's, ore
mined from the Comstock Lode near Virginia City was transported to any of 75 (or more) mills,
where it was crushed and mixed with mercury to amalgamate the gold and silver (Reference 1, page
1). Due to the availability of water power, 12 mill sites in the Brunswick Canyon area of Carson
River dominated (Reference 1, page I).
Liquid mercury was imported and used in the amalgamation of gold and silver in the ratio of 1:10,
mercuryore. The average loss of mercury was 0.68 kg for each ton of ore milled (Reference 5, page
1). It has been estimated that about 14 to IS million pounds of mercury were lost during the
operation of these mills of which only 0.5 percent was later recovered (Reference 3, page 58,
Reference 5, page I).
From 1906 to 1914, mercury was recovered from tailings at Douglas Mill in Six Mile Canyon. The
operators (unknown) of the quicksilver mine recovered approximately 75,000 pounds of mercury
using cyanide and flotation (Reference 2, page 44). Later, the Alhambra Mine company also
attempted to recover mercury from contaminated waste piles. Alhambra used a cyanide leaching
process to recover gold, silver, and mercury. Alhambra's reprocessing operation lasted from
December 1984 to July 1986; it is not known how much gold, silver, and mercury they were able to
recover (Reference 7, page 38).
The Lahontan Reservoir has trapped Carson River sediments since it was constructed in 1915, acting
as a sink for mercury-contaminated sediments (Reference 5, page i). Prior to dam construction in
1915, "large quantities of mercury" may have been transported past the site of the current
impoundments (Reference 5, page i). According to EPA Region IX, it has not been determined if
areas below the dam will be included in the Remedial Investigation/Feasibility Study. It is a possible
that the results from an ecological assessment of the area below the dam may encourage EPA to
include this area in the Carson River Superfiind Site.
It is not known when operations at the mills ceased, however, the peak activity reportedly occurred in
the 30-year period from 1865 to 1895 The mills have since been demolished. The Carson River and
the Lahontan Reservoir are owned by the State of Nevada.
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Mining Waste NPL Site Summary Report
SITE CHARACTERIZATION
In 1987 and 1988, Ecology and Environment, Inc., reassessed all Preliminary Assessments in the
Comprehensive Environmental Response Compensation and Liability Information System (CERCLIS)
for the Carson River site. In this reassessment (in April 1988), Ecology and Environment indicated
that the possible exposure pathways included ground water, surface water, air, and the food chain
(Reference 4, page 3). Note that information in this NPL Site Summary Report on waste quantities
and the number and location of waste sources should be considered, at best, as approximations, since
a few sources dating back several decades have been cited in nearly all recent site descriptions. This
report simply cites the recent studies and does not attempt to trace responsibility for sources. The
Remedial Investigation/Feasibility Study for the site was initiated in September 1990 and, when
completed, will provide additional data.
The contaminant of concern is mercury (Reference 1, page 6). Mercury is quickly removed from
solution in water. Even where mercury contamination has occurred, mercury is rarely detected in
water samples. Instead, mercury becomes associated with sediments and organic matter, although
water plays a major role in mercury transport and deposition (Reference 5, page 4).
Sampling of mill tailings, sediments, surface water, ground water, and fish tissues from the Carson
River have been conducted in the course of site investigations and routine samplings since 1971
(Reference L, Sample Analysis Section, page 3).
Tailing Piles
In the late 1880's, ore was mined in the Comstock Lode and transported to mills along the Carson
River and its tributaries, where it was crushed and mixed with mercury to amalgamate the gold and
silver (Reference 1, page 1). An estimated 7,500 tons of mercury were lost during the milling
process, much of which was incorporated into mill tailings. The precise number of tailings piles at
the Carson River site is unknown, but is estimated to be in the hundreds (Reference 1, page 1). The
tailing piles are uncovered, unlined, and have never had any type of containment (Reference 1, page
5).
Sampling of tailing pile Number 3 near Six Mile Canyon was conducted by NDEP in May 1986. The
222 cubic yards of tailings in pile Number 3 was found to be contaminated with 493 ppm of mercury
Samples from tailing pile Number 3 were used in determining the waste quantity for the Hazard
Ranking System score for the site. However, the Hazard Ranking System notes that the waste
quantity estimated from pile Number 3 is expected to vastly under-represent the total waste quantity at
the site (Reference 1, pages 12 and 13).
5

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Carson River
Sediments
Sediment samples were collected from 15 stations along the Carson River system (see Figure 2).
Sampling occurred from May 1983 through December 1984 (from the California State line to the
Carson Sink). Samples collected five times from the river bottom consisted of material that was
predominantly underwater. In addition, samples were taken four times from a mercury-rich sediment
layer that was above the river bottom and only underwater during moderate to high water flows
(Reference 5, page 9).
Mean sediment concentrations of mercury steadily increased downstream of New Empire, from 0.08
parts per billion (ppb) at New Empire (Station 4) to 5.44 ppb below Lahontan Reservoir at Station 10
Background mercury concentrations from samples taken at Stations 1, 2, and 3 (upstream of New
Empire) were consistently below detection (<0.25 ppb). High-velocity currents above Dayton in the
Brunswick Canyon, where the majority of the mercury originally entered the river, have eroded much
of the material from this reach of the Carson River to areas of lower velocity, downstream of Dayton
(Reference 5, page 9).
Sampling stations located off the main channel of the Carson River indicate, according to NDEP, that
mercury is well distributed throughout sediments in the Newlands Irrigation Project canal system.
Mercury concentrations for stations 11, 12, and 14 were <0.25 ppb, 2.45 ppb, and 2.49 ppb,
respectively (Reference 5, pages 9 and 13). The South Branch of the Carson River (Station 12) was
the main channel of the Carson River, and it once conveyed water to Carson Lake. The NDEP
suggests that Lahontan Reservoir now serves as a sediment-mercury trap. Mercury transported
downstream of the Lahontan Reservoir likely occurred before the construction of the Lahontan Dam
in 1915 (Reference 5, page 13).
Samples from a mercury-rich sediment layer had mercury concentrations approximately four times
higher than samples collected from the bottom layer. The highest concentration was 35.05 ppb
(found in Brunswick Canyon). This 1- to 2-foot deep stratum of mercury-rich sediments, which
NDEP speculated is the result of prior mercury mining, could not be detected at, or upstream of,
New Empire (Reference 5, page 13).
In a series of samples collected by the U.S. Geological Survey (USGS) in 1972, mercury
concentrations of bottom sediments from the Lahontan Reservoir ranged from 5.3 ppb to 20.0 ppb.
The Desert Research Institute conducted its own sampling of Lahontan Reservoir bottom sediments in
1980 and found mercury concentrations ranging from 1.3 to 23.0 ppb (Reference 5, page 17).
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Mining Waste NPL Site Summary Report
CA**o»
FIGURE 2. LOCATION OF SEDIMENT, WATER, AND nSH SAMPLING STATIONS

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Carson River
Surface sediment samples (from the top 2 to 4 inches) collected from transects in Lahontan Reservoir
in May 1985 had total mercury concentrations ranging from 2.8 ppb to 30.5 ppb. Only samples
collected from the meccury-rich layer of sediments had higher mercury concentrations (Reference 5,
page 15)
Surface Water
Water from the Carson River is used for the irrigation of approximately 1,200 acres of food and
forage crops between Dayton and the Lahontan Reservoir (Reference 1, page 13). The Carson River
and the Lahontan Reservoir are not used as a drinking water source, but water irrigates 250 acres of
land used for crops for human consumption (Reference 4, page 2). In addition, the Carson River is
used by 700,000 people for recreation and fishing.
The NDEP collected surface-water samples from the same stations used for sampling sediments (see
Figure 2). The samples were collected from May 1983 to December 1984. Of the 46 background
samples collected at Stations 1, 2, and 3 [located upstream of New Empire (Station 4)], only three
samples were above the 0.5 ppb detection limit. Only 4 of the 44 samples taken from the reach of
the Carson River (where the majority of the mills were located) had mercury concentrations levels
above detection. Mean concentrations in this reach of the river (at Stations 4, 5, and 6) were 0.04
ppb, 0.1 ppb, and 0.1 ppb, respectively (Reference 5, page 17).
The highest surface-water concentrations of mercury were found between Dayton and the Lahontan
Reservoir. The Chaves Ranch station (Station 7) had mercury concentrations ranging from less than
0.5 to 5.1 ppb, and had a mean of 0.9 ppb. The Weeks Ranch station (Station 8) had the highest
mean and maximum concentrations of any station, mercury concentrations ranged from 2.2 to 15.0
ppb and had a mean of 5.1 ppb. Twenty-one of the 32 samples taken at these two stations were
above the detection level (Reference 5, page 17).
Samples from stations below the Lahontan Reservoir had mercury concentrations similar to those
upstream of Dayton. Only 3 of the 16 samples in this reach of the Carson River were above
detection levels. The maximum concentration measured was 0.7 ppb at Station 10. NDEP suggests
that two factors may influence mercury concentrations below the dam. First, a sufficiently long
detention time for water in the reservoir (9 months) allows for substantial settling of sediments to
which mercury is bound. Second, the Lahontan Dam reduces seasonal fluctuations of water, and
consequent scouring of sediments, in downstream reaches (Reference 5, page 20).
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Mining Waste NPL Site Summary Report
Two of the five sampling sites (Stations 11 and 15) located on canals and drains of the Newlands
Irrigation Project had mean mercury concentrations of 0.2 ppb and 0.1 ppb, respectively. Seven of
22 (22 percent) exceeded the detection limit of 0.5 ppb. The remaining three sampling sites (Stations
12, 13, and 14) had high mean mercury concentrations of 1.3 ppb, 0.7 ppb, and 1.3 ppb,
respectively. Seventy-three percent (35 of 48) of the samples exceeded detection limits (Reference 5,
page 20).
Ground Water
Ground water is the drinking water source along the Carson River. The population using ground
water in the area has not been determined; however, there are many residential developments along
the banks of the River and Lahontan Reservoir that are not served by a public water system
(Reference 1, Summary).
The regional ground-water flow system in the Carson River Basin above Lahontan Dam is generally
downstream toward the reservoir and is mainly controlled by the surface-water levels. Some water
seeps from the reservoir through volcanic rocks and associated alluvial deposits (Reference 9, page
15).
The Dayton Valley aquifer was used to define the aquifers of concern for Hazard Ranking System
scoring. The Dayton Valley aquifer is an unconfined aquifer of interbedded clays, sands, and gravels
underlying Six Mile Canyon (Reference I, page 3).
The Dayton Valley Estates Water Company draws well water from the Dayton Valley Aquifer to
serve 139 homes. The wells are 1.25 miles from mercury-contaminated tailing piles. In the Dayton
Valley area, there are at least 226 other occupied buildings (private residences) not served by a public
water supply which are within 3 miles of either the Carson River or mercury-contaminated tailing
piles. At least 30 of the residences not served by a public water supply are within 2,000 feet of the
Carson River or the contaminated piles. There are no alternative drinking water sources for these
residences (Reference 1, Sample Analysis Section, page 4).
Ground-water samples from domestic and monitoring wells from Brunswick Canyon to Lahontan
Reservoir were found to have mercury concentrations of less than 0.0005 ppm. In addition, ground-
water concentrations for cadmium, chromium, lead, selenium, and silver were all less than 0.001
ppm. Sampling was conducted during November 1986 (Reference 7, page 39).
9

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Carson River
Mercury has not been detected above background levels in drinking water wells (Reference 1, Sample
Analysis Section, page 4; Reference 6, pages 1 and 2) or monitoring wells (Reference 7, pages 35
through 38).
Air
Limited air sampling has been conducted over the tailings piles. Mercury vapors were Not Detected
(ND) when sampling was performed on a day with a temperature of 85°F. At higher temperatures
(temperatures in the area can exceed 100°F) or under windy conditions [winds can gust up to 40 to
100 miles per hour (mph)], mercury vapors or mercury-contaminated dust could result in detectable
concentrations (Reference 8, page 1) Approximately 300 residents could be exposed to airborne
mercury contamination (Reference 1, Sample Analysis Section, page 6).
ENVIRONMENTAL DAMAGES AND RISKS
Possible exposure pathways are ground and surface water, soil, air, and through the food chain.
Mercury is both highly toxic and persistent, and receives the highest toxicity/persistence matrix value
(18) in Hazard Ranking System scoring (Reference 1, Sample Analysis Section, page 3). Metallic
mercury volatilizes easily at ambient temperatures; the vapor is liquid-soluble, with an affinity for the
central nervous system, red blood cells, and other tissues (Reference 10, page 22). Also of concern
is methyl mercury, obtained from fish, which in turn obtain it directly and indirectly from
contaminated sediments (via bacterial conversion of inorganic mercury) (Reference 10, page 22).
Chronic effects of mercury poisoning are complex and variable, but focus largely on the central
nervous system and kidneys. Chronic inorganic and organic vapor poisoning is somewhat reversible,
but chronic poisoning from methyl mercury is usually irreversible. Chronic organic mercury
poisoning usually involves paresthesia, visual field constriction, hearing loss, dysarthria, and ataxia.
In the fetus, chronic methyl mercury intoxication leads to psychomotor retardation and cerebral palsy
as a consequence of abnormal brain development (Reference 10, page 23).
The Carson River is used by 700,000 people for recreation, fishing, and irrigation (Reference 1,
Sample Analysis Section, page 2). The Lahontan Reservoir is the fifth largest recreational and
commercial fishery in Nevada. Commercial fish harvested from the Lahontan Reservoir are
transported to restaurants and markets in the San Francisco Bay area (Reference 4, page 2).
During the summer of 1981, fish were collected to determine the mercury concentration in fish
tissues. Results indicated that significant mercury accumulation is occurring within fishes of the
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Mining Waste NPL Site Summary Report
Lahontan Reservoir. Mercury concentrations in muscle tissue ranged from 0.11 milligrams per
kilogram (mg/kg) in young-of-the-year white bass to 9.52 mg/kg in striped bass. Of the 53 muscle
tissues analyzed, 36 (68 percent) exceeded the 1 mg/kg "action level" considered safe by the Food
and Drug Administration. Mercury concentrations in heart tissues ranged from 0.17 mg/kg in carp to
5.58 mg/kg in striped bass. Liver tissues had mercury concentrations ranging from 0.21 mg/kg in
brown bullhead to 23.65 mg/kg in striped bass. These levels are considerably higher than the 0.20
mg/kg considered background for fish. In general, mercury concentration within species increased
with fish weight (Reference 11, page 11).
In 1986, the Nevada Department of Wildlife and Consumer Health Protection Services issued a fish
consumption advisory. The Department recommended that no more than one meal of fish (8 ounces)
caught in the Lahontan Reservoir or outfall waters below the reservoir should be eaten each week
because of possible toxicity from mercury; and no child or woman of child-bearing age should
consume any fish from these waters (Reference 12, page 15). The Health Advisory was expanded
and reissued in 1987 to indicate that no more than one meal of fish per month should be eaten, and
walleye over 21 inches long should not be eaten (Reference 13).
Approximately 1,200 acres of food and forage crops are irrigated by the Carson River between
Dayton and the Lahontan Reservoir (Reference 1, page 1). However, no studies were found that
indicated or described the presence of mercury in food or forage crops at the site.
Although water drained from the Lahontan Reservoir through canals is used mainly for irrigation,
some canal water also drains into the Stillwater Marsh. Most of the water entering the Stillwater
Marsh is reportedly irrigation return flows. The Stillwater Wildlife Management Areas is a major
breeding ground and stopover for hundreds of thousands of birds migrating on the Pacific Fly way.
Fish and bird kills in the Carson Sink have been attributed to increased salinization of the water, and
possibly increased susceptibility of the wildlife to disease due to elevated levels of potentially toxic
elements such as arsenic and selenium (Reference 7, page 44). Mercury was ND at the Stillwater
Marsh Reservoir outlet during NDEP sampling in 1983 and 1984 (Reference 7, page 11).
REMEDIAL ACTIONS AND COSTS
A Remedial Investigation/Feasibility Study was initiated for the Carson River site in September 1990.
Therefore, little information on possible remedial actions is available at present. EPA suspects that
the only feasible way to deal with the contaminated tailing piles is to stabilize them onsite to control
mercury vapors and leaching (Reference 3, page 70). NDEP suggested in 1986 that the only
environmentally sound action to address mercury contamination in Lahontan Reservoir would be to
11

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Carson River
impound stream water before it enters the Reservoir, during the snow melt season. The water would
then be allowed to sit until the suspended mercury had settled out. This remedy would involve a
large diffusion and retention system (Reference 14). Both of these "alternatives" should be
considered as speculative, pending completion and EPA approval of the Remedial Investigation/
Feasibility Study.
CURRENT STATUS
The Carson River site was listed on the NPL in August 1990 (55 Federal Register 35502) According
to Region IX, EPA is currendy searching for PRPs. The Remedial Investigation/Feasibility Study is
currently being performed.
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Mining Waste NPL Site Summary Report
REFERENCES
I.	Hazard Ranking System Score Sheet, Sample Analysis and Documentation for the Carson River
Mercury Site; Ecology and Environment; May 22, 1989.
2 Total Mercury in Water, Sediment, and Selected Aquatic Organisms, Carson River, Nevada -
1972; R.T. Richins and A.C. Risser, Pesticides Monitoring Journal 9, No. 1; June 1975.
3. Corrected Transcript of Testimony Given Before the Subcommittee on Superfund, Ocean, and
Water Protection on February 12, 1990, Alexis Strauss, EPA Region IX; March 6, 1990.
4 Memorandum Concerning Review of the Preliminary Assessment for the Carson River Mercury
Site; From Bill Malloch, Ecology and Environment, to Paul La Courreye, EPA; August 24,
1987
5.	Total Mercury in Sediment, Water, and Fishes in the Carson River Drainage, West-Central
Nevada; NDEP; December 1985.
6.	Mercury in the Carson and Truckee River Basins of Nevada, Open-file Report; A.S. Van
Denburgh, USGS; 1973.
7.	Reconnaissance Survey of Ground-water Quality in the Carson River Basin; NDEP; January
1988.
8.	Persona] Communication Concerning Carson River Mercury Contamination; From James Cooper,
NDEP, to Bill Malloch, Ecology and Environment; May 10, 1988.
9.	Water Resources Appraisal of the Carson River Basin, Western Nevada, Water Resources
Reconnaissance Series, Report 59; Nevada Division of Water Resources; 1975.
10.	Remedial Investigation Report, Silver Mountain Mine Okanogan County, Washington; Volume
2 -- Appendices, Draft; EPA; December 15, 1989.
II.	Total Mercury in Fishes and Selected Biota in Lahontan Reservoir, Nevada: 1981; James
Cooper, Bulletin of Environmental Contamination Toxicology, 31:9-17; 1983.
12.	Job Progress Report Concerning Carson River Contamination and Endangered Species; From
Mike Sevon, Nevada Department of Wildlife, to Bill Malloch, Ecology and Environment; May
18, 1988.
13.	Health Advisory; Nevada Department of Human Resources, Health Division; May 1987.
14.	Record of Communication Concerning Carson River Mercury Site File; From Heather Stone to
James Cooper and A. Biagti, NDEP; August 14, 1986.
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Carson River
BIBLIOGRAPHY
Cooper, James (Bulletin of Environmental Contamination Toxicology). Total Mercury in Fishes and
Selected Biota in Lahontan Reservoir, Nevada: 1981, 31:9-17. 1983.
Cooper, James (NDEP). Contact Report Concerning Carson River Mercury Contamination to Bill
Malloch, Ecology and Environment. May 18, 1988.
Cooper, James and S. Vigg. Extreme Mercury Concentrations of a Striped Bass, Morone saxatilis.
With a Known Residence Time in Lahontan Reservoir, Nevada. California Fish and Game,
70(3): 190-192. 1984.
EPA. Potential Hazardous Waste Site, Site Identification, EPA Form 2070-11, Carson River
Mercury Site. March 24, 1983.
Flom, Duane (Nevada Cooperative Extension). Letter Concerning Information on Irrigated Crops
Adjacent to the Carson River in Lyon County to Karen Ladd, Ecology and Environment.
March 27, 1989.
Hazard Ranking System Score Sheet, Samples Analysis and Documentation for the Carson River
Mercury Site. Ecology and Environment. May 22, 1989.
Ladd, Karen (Ecology and Environment). Contact Report Concerning Irrigation Uses of Carson
River to Duane Flom, University of Nevada-Reno, Nevada Cooperative Extension. March 28,
1989.
Malloch, Bill (Ecology and Environment). Memorandum Concerning Review of the Preliminary
Assessment for the Carson River Mercury Site to Paul La Courreye, EPA. August 24, 1987
NDEP. Reconnaissance Survey of Ground-water Quality in the Carson River Basin. January 1988.
NDEP. Total Mercury in Sediment, Water, and Fishes in the Carson River Drainage, West-Central
Nevada. December 1985.
Nevada Department of Human Resources, Health Division. Health Advisory. May 1987.
Nevada Division of Water Resources. Water Resources Appraisal of the Carson River Basin,
Western Nevada, Water Resources Reconnaissance Series, Report 59. 1975.
PA Reassessment of Carson River Mercury Site. Ecology and Environment. April 25, 1988.
Richins, R.T. and A.C. Risser. Total Mercury in Water, Sediment, and Selected Aquatic Organisms,
Carson River, Nevada - 1972, Pesticides Monitoring Journal 9, No. I. June 1975.
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Mining Waste NPL Site Summary Report
Sevon, Mike (Nevada Department of Wildlife). Job Progress Report Concerning Carson River
Contamination and Endangered Species to Bill Malloch, Ecology and Environment. May 18,
1988.
Stone, Heather Record of Communication Concerning Carson River Mercury Site File to James
Cooper and A. Biagti, NDEP. August 14, 1986.
Strauss, Alexis (EPA-IX). Corrected Transcript of Testimony Given Before the Subcommittee on
Superfund, Ocean, and Water Protection on February 12, 1990. March 6, 1990.
Van Denburgh, A.S. (USGS). Mercury in the Carson and Truckee River Basins of Nevada, Open-
file Report. 1973.
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Carson River
Mining Waste NPL Site Summary Report
Reference 1
Excerpts from Hazard Ranking System Score Sheet,
Sample Analysis and Documentation for the Carson River Mercury Site;
Ecology and Environment; May 22,1989

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Facility Name: Carson River Mercury Site	
Location: The Carson River, beginning between Carson
City and Dayton, through the Lahontan	
Reservoir, Nevada.
EPA Region: IX	
Person(s) in charge of the facility: Jim Cooper	
Nevada Division of
Environmental Protection
201 South Fall Street
Carson City, NV 94710
Name of Reviewer: Karen Ladd	 Date: 05/22/89
General description of the facility:
The Carson River Mercury Site (CRMS) is an approximately 50-mile
stretch of the Carson River, beginning between Carson City and
Dayton, Nevada and extending downstream through the Lahontan
Reservoir. In the late 1800s, numerous ore milling sites operated in
Brunswick Canyon, Six Kile Canyon, and along the Carson River, where
crushed ore mined from the Comstock Lode near Virginia City, Nevada
was mixed with mercury to amalgamate the precious metals (Ref. 1;
Ref. 4; Ref. 21). Mercury contaminated tailings piles which
resulted from the mill site operations have been found 5 miles up
Brunswick Canyon, 3 miles up Six Mile Canyon, and within the Carson
Plains (Ref. 2; Ref. 15). Areas near the Comstock Lode where
extensive mining occurred, such as in Gold Canyon, may also be major
potential sources of mercury contaminated mine tailings piles (Ref.
25). Annual rains transport mercury from the tailings piles in the
canyons to the Carson River, where extensive contamination due to
mercury has been documented (Ref. 2). The CRMS consists of the
mercury contaminated tailings piles and sediments which resulted from
the mill site operations. The contamination routes of major concern
are the groundwater route and the surface water route, since
groundwater is used for drinking water purposes and surface water is
used for irrigation (Ref. 9; Ref. 11; Ref. 13*, Ref. 14; Ref. 17; Ref.
18; Ref. 19; Ref. 26; Ref. 27; Ref. 28).
Scores Su = 39.07 (S = 49.39 S = 46.15 S„ = N/A)
M	gw , sv	a
SpE = N/A
FIGURE 1
HRS COVER SHEET
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Aggregate^
The Carson River Hercury Site (CRMS) is an approximately 50-mile stretch of
the Carson .River, beginning between Carson City and Dayton, Nevada and
extending dovnscream through the Lahontan Reservoir (see Carson River
Mercury Site Map).
Large amounts of mercury vere used during the milling of the Comstock Lode
near Virginia City, Nevada in the late 1800s (Ref. 1; Ref. 6; Ref. 21).
Ore mined from the Comstock Lode vas transported to any of 75 mill sites
where it was crushed and nixed with mercury to aaalgaoate the precious
metals (Ref. 1; Ref. 4). Twelve mill sites along the Carson River in the
Brunswick Canyon area became dominant, due to the availability of water
power (Ref. 1; Ref. 4).
Mercury contaminated tailings piles which resulted from the mill site
operations have been found 5 miles up Brunswick Canyon, 3 miles up Six Mile
Canyon, and within the Carson Plains (Ref. 2; Ref. 12; Ref. IS; Ref. 19).
Areas near the Comstock Lode where extensive mining occurred, such as in
Gold Canyon, may also be major potential sources of mercury contaminated
mine tailings piles (Ref. 23). Annual rains transport mercury from the
tailings piles in the canyons to the Carson River, where extensive
contamination due to mercury has been docuaented (Ref. 1; Ref. 2). The
CRMS consists of the mercury contaminated tailings piles and sediments
which resulted from the mill site operations.
The Nevada Division of Environmental Protection (NDEP) conducted sampling
of water and sediments from the Carson River between 1983-1986. Elevated
levels of mercury were detected in the saaples which were taken from above
the Dayton area, through the Lahontan Reservoir, to the cutoff of the
Stillwater Slough (Ref. 2; Ref. 3). The source of this mercury has been
traced to the mercury contaminated tailings piles, because sample results
shoved levels of mercury in the water and sediments from the Carson River
significantly above background (greater than 5 times) (Ref. 1; Ref. 3). In
May 1986, the NDEP detected levels of up to 493 parts per million (ppm)
mercury in tailings piles and sediments from Six Mile Canyon and Six Mile
Canyon Creek (Ref. 15).
The sampling efforts conducted by the NDEP in May 1986 showed tailings pile
No. 3, which is near the Six Mile Canyon Creek Drainage, to be contaminated
with 493 ppm mercury (Ref. 15). According to the NDEP, tailings pile No. 3
is one of hundreds of mercury contaminated tailings piles which are in
Brunswick and Six Mile Canyons (Ref. 24). It has been estimated that 7,500
tons of mercury were lost in the milling process during the 30-year peak of
the Comstock Lode, only about 0.5Z of which was later recovered (Ref. 1).
Much of the mercury which escaped recovery was incorporated in the mill
tailings (Ref. 23; pg. 2). For HRS purposes, only tailings pile No. 3 was
used to define the waste quantity for the site, since sampling conducted to
date has documented it to be contaminated with mercury (Ref. 15). However,
due co the large number of tailings piles that exist in Brunswick and Six
Mile Canyons, and potentially in Gold Canvon. and due to the amount of
mercury which was lost during milling, the waste quantity estimated from
the single tailings pile No. 3 is expected to vastly underrepresent the
total waste quantity of the site.
1
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DOCUMENTATION RECORDS
FOR
HAZARD RANKING SYSTEM
INSTRUCTIONS: The purpose of these records is to provide a
convenient way to prepare an audi table record of the data and
documentation used to apply the Hazard Ranking Systeo to a given
facility. As briefly as possible summarize the information you used
to assign the score for each factor (e.g., "Vaste quantity - 230
drums plus 800 cubic yards of sludges'1). The source of information
should be provided for each entry and should be a bibliographic-type
reference that will matte the document used for a given data point
easier to find. Include the location of the document and consider
appending a copy of the relevant page(s) for ease in reviev.
FACILITY NAME: Carson River Mercury Site	
LOCATION: 	The Carson River, beginning between Carson City
and Dayton, through the Lahontan Reservoir. Nevada
DATE SCORED: May 22. 1989	
PERSONS SCORING: Karen Ladd. Bill Malloch. Julie Noffke	
PRIMARY SOURCE(S) OF INFORMATION (e.g., EPA Region, state. FIT, etc.):
State and FIT files.
FACTORS NOT SCORED DUE TO INSUFFICIENT INFORMATION:
Air, Fire and Explosion, and Direct Contact routes not scored.
COMMENTS OR QUALIFICATIONS:
Milling operations vhich occurred in the 1800s during the mining of the
Comstock Lode in Nevada resulted in mercury contamination of water and
sediments in the Carson River. The Carson River Mercury Site is defined
as the stretch of the river beginning between Carson City and Dayton.
Nevada downstream through the Lahontan Reservoir, since sampling has
clearly documented this entire segment to be mercury contaminated. It
should be noted that mercury contamination has also been detected in
samples downstream as far as the cutoff of the Stillwater Slough.
However, the flow of the Carson River becomes complicated below the
Lahontan Reservoir due to its expansion into an extensive irrigation
canal system. Sampling has not shown consistent mercury contamination
belov the reservoir, therefore, for HRS purposes, this segment is not
considered to be part of the site.
2
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GROUND VATER ROUTE
1 OBSERVED RELEASE
Contaminant detected (S maxima):
No observed release to groundwater.
Score • 0 (Ref. 7, pg. 9)
Rationale for attributing the contaminants to the facility:
2 ROUTE CHARACTERISTICS
Depth to Aquifer of Concern
Naae/description of aquifer(s) of concern:
The Carson River Basin comprises five hydrographic areas which
include: r*r«nn Va^ey, Eagle Valley, Dayton Valley, Churchill
Valley, and the Carson Desert (Ref. 9, pp. 13-14). The Dayton Valley
Aquifer underlies the Six Mile Canyon area (Ref. 9, pg. 13; Ref. 10).
For HRS purposes, the Dayton Valley Aquifer is used to define the
aquifer of concern. The Dayton Valley Aquifer is an unconfined
aquifer comprised of interbedded clays, sands, and gravels (Ref. 9,
pg. 13; Ref. 10).
Depth(s) from the ground surface to the highest seasonal level of
the saturated zone [water table(s)l of the aquifer of concern:
According to well logs, static water levels for wells drawing from the
Dayton Valley Aquifer are typically betveen 50-200 feet, depending on
the distance to the Carson River (Ref. 9, Table 39; Ref. 10). Static
water levels are shallover for wells nearer the river, and are deeper
for wells farther from the river (Ref. 9, Table 39; Ref. 10). The top
of the aquifer slopes toward the river, but the elevation of the
ground surface increases at a faster rate toward the mountains, so the
depth from ground surface to the top of the aquifer increases vith
distance from the river (Ref. 10). The top of the Dayton Valley
Aquifer is found generally from 5-300 feet belov ground surface,
depending on the proximity to the river (Ref. 10).
N/A
* * *
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3

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Permeability of Unsaturated Zone
Soil type in unsaturated zone:
The unsaturated zone consists of consolidated igneous, metamorphic,
and sedimentary deposits, and unconsolidated to semi-consolidated
valley-fill deposits of clays, silts, sands, and gravels (Ref. 9, pp.
1, 12, 13; Ref. 10).
Pemability associated vith soil type:
The soils associated vith the least permeable continuous layer consist
of unconsolidated deposits of alluvium comprised of sills, sands, and
gravels (Ref. 9, pg. 12; Ref. 10). Permeability is 10~ -10" cm/sec.
Score ¦ 2 (Ref. 7, pg. 15)
Physical State
Physical state of substances at tiae of disposal (or at present time
for generated gases):
Povder or fine material (Ref. 1, pp. 1-3).
Score ¦ 2 (Ref. 7, pg. 16)
3 CONTAINMENT
Containment
Method(s) of waste or leachate containment evaluated:
Tailings piles containing mercury levels up to A93 ppm are located up
Six-Mile Canyon and vithm the Carson Plains area (Ref. 1, pp. 1-3;
Ref. IS). These piles represent vaste material from the "Uashoe
Process," and have never had any type of containment (Ref. 2).
Method vith highest score:
Tailings piles uncovered, vaste unstabilized. and no liner.
Score ¦ 3 (Ref. 7, pg. 17)
* * *
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5

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4 VASTZ CHARACTERISTICS
Toxicity and Persistence
Coepound(s) evaluated:
Ref. 7,
Ref. 8	pg. 18
Toxicity Persistence
Ref. 7,
pg. 18
T/P Matrix Value Reference
Mercury
3
3
18
1. PP- 9, 11
Compound vitb highest score:
Mercury
Matrix Score - 18 (Ref. 7, pg. 18)
Hazardous ffaate Quantity
Total quantity oC hazardous substances at the facility, excluding
those vith a containment score of 0 (Give a reasonable estiaate even
if quantity is above aaxiaua):
The total hazardous vaste quantity is 222 cubic yards.
Score = 4 (Ref. 7, pg. 19)
Basis of estiaating and/or computing vaste quantity:
The sampling efforts conducted by the NDEP in May 1986 shoved tailings
pile No. 3, which is near the Six Hile Canyon Creek. Drainage, to be
contaminated vith 693 ppa mercury (Ref. IS). According to the NDEP,
tailings pile No. 3 is one of hundreds of mercury contaminated
tailings piles which are in Brunswick and Six Mile Canyons (Ref. 24).
It.has been estimated that 7,500 tons of mercury were lost in the
milling process during the 30-year peak of the Comstock Lode, only
about 0.5X of vhich was later recovered (Ref. 1). Much of the mercury
which escaped recovery was incorporated in the mill tailings (Ref. 23,
p. 2). For HRS purposes, only tailings pile No. 3 was used to define
the waste quantity for the site, since sampling conducted to date has
documented it to be contaminated with mercury (Ref. IS). However, due
to the large number of tailings piles that exist in Brunswick and Six
Mile Canyons, and potentially in Gold Canyon, and due to the amount of
mercury vhich was lost during milling, the waste quantity estimated
from the single tailings pile No. 3 is expected to vastly
underrepresent the total vaste quantity of the site.
6
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Tailings pile No. 3 Is estimated to be approximately 100 feet long, IS
feet vide, with an average height of 4 feet (Ref. 15; Ref. 24).
To calculate the hazardous vaste quantity:
100 ft. x IS ft. x 4 ft. ¦ 6000 cubic feet
6000 cubic feet x A cu' - 222.22
n cu. ct.
Total ¦ 222 cubic yards
* * *
5 TARGETS
Ground Vater Use
Use(s) of aquifer(s) of concern within a 3-aile radius of the
facility:
Groundwater is used for municipal, domestic, and industrial purposes
(Ref. 9, pg. 55).
The Oayton Valley area has no alternative drinking vater source
available (Ref. 13).
Score - 3 (Ref. 7, pg. 24)
Distance to Nearest Well
Location of nearest well drawing froa aquifer of concern or occupied
building not served by a public water supply:
The Dayton Valley Estates Vater Company veils which serve 139 hones
are located vithin 3 miles of the mercury contaminated tailings piles
vhich-are 3 miles up Six Hile Canyon and within the Carson Plains (see
Location Map for Dayton Valley Estates Vater Company Veils, Ref. 19).
The veils are located at the intersection of Six Hile Canyon Road and
Ring Road (Ref. 11; Ref. 12; Ref. 13; Ref. 19; Ref. 28). The Dayton
Valley Estates Vater Company veils have screened intervals between 65
and 173 feet in the unconfined, alluvial Dayton Valley Aquifer (Ref.
10; R«f. 13). The depth to vater for Dayton Valley Estates Vater
Company Veil No. 4 is 52.7 feet (Ref. 16).
In the Dayton Valley area, there are at least 226 other occupied
buildings (private residences) not served by a public water supply
vhich are vithin 3 miles of either the Carson River or mercury
contaminated tailings piles (Ref. Ref. 28). At least 30 occupied
buildings not served by a public '.irer supply are within 2,000 feet of
the Carson River oi mercurv contaminated tailings piles, in the Dayton
Valley area (Ref. 19; Ref. 28).	^>_
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4 VASTE CHARACTERISTICS
Toxicity and Persistence
Coapound(s) evaluated:
Ref. 7,
Ref. 8	pg. 18
Toxicity Persistence
Ref. 7,
pg. 18
T/P Matrix Value Reference
Mercury
3
3
IB
1, PP- 9, 11
Coapound vith highest score:
Mercury
Matrix Score ¦ 18 (Ref. 7, pg. 18)
Hazardous Waste Quantity
Total quantity of hazardous substances at the facility* excluding
those vith a containaent score of 0 (Give a reasonable estimate even
__if quantity is above aaxiaua):
The total hazardous vaste quantity is 222 cubic yards.
Score > 4 (Ref. 7, pg. 19)
Basis of estiaating and/or computing vaste quantity:
The sampling efforts conducted by the NDEP in May 1986 shoved tailings
pile No. 3, vhich is near the Six Hile Canyon Creek Drainage, to be
contaminated vith 493 ppm mercury (Ref. 15). According to the NDEP,
tailings pile No. 3 is one of hundreds of mercury contaminated
tailings piles vhich are in Brunswick and Six Mile Canyons (Ref. 24).
It has been estimated that 7,500 tons of mercury vere lost in the
milling process during the 30-year peak of the Comstock Lode, only
about 0.5Z of vhich vas later recovered (Ref. 1). Much of the mercury
vhich escaped recovery vas incorporated in the mill tailings (Ref. 23,
p. 2). For HRS purposes, only tailings pile No. 3 vas used to define
the vaste quantity for the site, since sampling conducted to date has
documented it to be contaminated vith mercury (Ref. 15). Hovevec, due
to the large number of tailings piles that exist in Brunsvick and Six
Mile Canyons, and potentially in Gold Canyon, and due to the amount of
mercury vhich vas lost during milling, the vaste quantity estimated
from the single tailings pile No. 3 is expected to vastly
underrepresent the total vaste quantity of the site.
k/kl/cariv/hrs
12

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Tailings pile No. 3 is estimated to be approximately 100 feet long, 15
feet vide, vith an average height of 4 feet (Ref. 15; Ref. 24).
To calculate the hazardous waste quantity:
100 ft. x 15 ft. x 4 ft. « 6000 cubic feet
6000 cubic feet x * cu- yd. , 222.22
to/ cu~ c t.
Total « 222 cubic yards
* * *
5 TARGETS
Surface Water Use
Use(s) of surface vater vithin 3 ailes dovnstrean of the hazardous
substance:
Approximately 1,200 acres of food and forage crops are irrigated by
the Carson River betveen Dayton and the Lahontan Reservoir (Ref. 27;
Ref. 29). The Carson River is not currently used for drinking vater
purposes. The Carson River and the Lahontan Reservoir are the fifth
largest recreational and commercial fishery in the State of Nevada
(Ref. 5).
Score i 2 (Ref. 7, pg. 34)
Is there tidal influence?
There is no tidal influence vithin the site's boundaries (Ref. 12).
Distance to a Sensitive Environaent
Oistance to 5-acre (ainiaua) coastal wetland, if 2 ailes or less:
N/A
Distance to 5-acre (ainiaua) fresb-vater wetland, if 1 mile or less:
N/A
13
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L?
I,

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Carson River
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Total Mercury in Water, Sediment, and
Selected Aquatic Organisms, Carson River, Nevada - 1972;
R.T. Richins and A.C. Risser, Pesticides Monitoring Journal 9, No. 1;
June 1975

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James J. Cooper
^Printed with permission by the U.S. ENVIRONMENTAL PROTECTION AGENCY
Fran PESTICIDES MONITORING JOURNAL
Volme 9, Nunber 1, June 197S
		 4
lUiltowiriri*
Nbwb
K)vJP61g>0g?t 5 (gAU,
7"o/ai Mercury in Water. Sediment, and Selected Aquatic
Organisms, Carxan River, Nevada—1972 1
Rohrrt I Rnhin«. ind Arthur ( Ki»mi li 1
AHS"IRA(T
4 IVTf.fJ ttmiv ttf tkf Hnmi* ( mium Ki*rr Ufainmtr »»»-
Inm tf tAf Gro/ufira/ Stiff*. tl \ lirpmrtmrnt nf iMtrinr,
rrrrulfj tmittmttal mmtmnti III mrrrmr-* front frrf. I WW titid
uhi/ tUrrt milling nfirmiumi uf iht (omttaet Lotif A
niMiiwIiu t*frf» m innutrj m ,inrtmmr tkr fitrm of
¦mi)/ apmkt J ram i nfttipumlmr f'tft "
trdimrau tar terra aqnnm iprrirt < tWrrfrW from Kff WW-
itatkmi atone tHr maimtmnr TiUnl mrrrtri riimrni
it M r»»f»W /rum IMJJ hi 2.72 iTm' h'thru citnrrnirt-
Itimt atrwrwi im ftiatrtrimt «hur *•
fmmt iibiiIwm betverm m-ri m nfhi mmJ nirrrmrr eonirni
«/ ^rr «/ Mr la t(wiri Cu*rmtrniumi alu¦ apprarrd in
kr dtrmlr tnlmmrrl hf I tit ipniri rnttitfm #m Mr tfnanc
/ibW rfcato. Tkrtr rrmlll inJicatr ikml mmur* Irrrlt in
*»•* Ul |mk dw f'arjrw Mirer ilraiimtf ml«* "t» rx-
i rrj ihf 0J0 ppm muwmmm < fwr«irorncni. are often influentcO
try ptopi*. Th*ir use of mcrvurjr hai itireaicnol hirU
pupulalMNa in Sweden (11 tnii u»m»rmna«ctJ lain jril
r»*cn m tome arca« nt the UniicO Sl.iiei renderiny fi«h
urbiaie for cunwmption (.'t rict|iKncr« of exptnure
lit inch acute concentrations are evuk-nt in rcpnm from
Minamata and Niigaia. Japan tJ ¦>>
Natural iouTO j)«o cuntrihiite lo mercury inniamtna-
¦ ikiwiM nt IMr, Ummn hft* Kna Nn
• via r«m CawN at tiummn )2] »	la an»«
I I n«M WWL >!¦— 11 limn t M l«» !!«¦
>m Oheite *m OMkiiitf.
turn (3). I iviU ill nimr.illy iKinrrtng mercury n hip
1.2**1 rr'» *v f>cvn ri-(vr:nf m «.
tcives approiiiii.iicly lOOIXHI rnn< til ntcfcury «nnu,,ll
fr»tm prci.ipii.iium I hn compares ui the yearly huma
prmluctnin hi .ihmit 10 INN) tun* I 7 i.
Since the fir** icuuiry B.C efentrnial mertury hm fx-ci
iisoi ui tttrj(.i and nlver from their ore* hy anui
famiiitin <*) I hut when the Nevttla Comiicxk I ixj
wa» i/iacovcrvil in the iprmy o< I*'' near Virginia Ciiv
Nev. (9). I.irpe jmounti ol the liauri m«tal were im
f*»rtv(j to 7^ millini >itf> in the area. In MM rm
riiad line* tiiinu ai theac met hecaiu
water p»»»vr w i\ .n.uljhlc t HI)
rhe Palm pn*v*> »hirh eniptoyeO jn a«era|te rhar^c t>
I ID qiiaitMlvcr i tin miry ) i ¦ > the weigfit of (he ore Ifi
wa* iivmI fur ctir.HtHin III) Thiwigh revnrd^ »re m
citmplctc. Hjivli .mil On \ tMimalct of total mereur
luat diirut| tin* Ut-v^ar peak of the Cumnock (I wr.5
IW^I are si hmh us 200 000 llaikl «vr apprnnmsicl
111BM)M) II) i/.'i These juihon also make Inrihc
reiercncc to the rvitoery of umcksil*tr from t.nlmp* ,i
the (J«ni|Jai Mill in Si*-Mil< Canyon helow Virgin
City Here iimiiu (.vinnlc and nutation methruN *hn.
had fifM N.-cn p^-ru-ilcd for ettractin| gold and iiIvc-t
the «ite* tailmits were reflned ^rnund IVOft Bctwei.1
I90(i and l^u the operation recovered o*vr t tto<
ilaaka of rncruiry.
Until the Ism dcLudc it wo itncnlly tcrepted thn
mctalliw mcanry titled to the bottom of a Nxjv r
water, paaing m» threat to the aouatic environmcm
Westnii (I I) hiTwever, reported that 90 percent ol ih
PuTicigti MoKmatiHO Jowi««i

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Carson River
Mining Waste NPL Site Summary Report
Reference 3
Excerpts From Corrected Transcript of Testimony Given
Before the Subcommittee on Superfund, Ocean, and Water Protection
on February 12,1990; Alexis Strauss, EPA Region IX; March 6, 1990

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UNITED STATES ENVIRONMENTAL PROTECTION AGENC
REGION IX
215 Rwnont Street
San Randsco, CA 94105
March 6, 1990
Paul Chimes
United States Senate
Committee on Environment and Public Works
Room SD-4S8
Dirksen Senate Office Building
Washington, DC 20510
Dear Mr. Chimes:
In response to your request of February 21, 1990 I am submitting a
list of corrections to the transcript of my testimony given before the
Sub/Committee on Superfund, Ocean, & Water Protection on February 12,
1990. Corrections are made in pencil on the original transcript with a line
by line list of typed corrections for clarity attached.
If you have any questions regarding the corrections, please feel free
to call me at (415) 744-1998.
Sincerely yours,
Alexis Strauss, Chief
Superfund Enforcement Branch

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+
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58
I09STATEMENT OF MS. ALEXIS STRAUSS, CHIEF OF THE ENFORCEMENT
BRANCH, SUPERFUND PROGRAM, REGION IX, ENVIRONMENTAL PROTECTION
AGENCY
Ms. Strauss. Good morning. I aa Alexis Strauss, Chief
of the EPA Superfund Enforcement Branch in our Region IX
office. Since EPA proposed that a stretch of the Carson River
be included on the National Priorities List on October 26,
1989, and since the Agency intends to aaXe a final decision
shortly, I wish to explain briefly our knowledge of site
conditions and our plans for finding a solution.
The site consists of a 50 to 100 aile stretch of the
Carson River and adjacent areas, contaminated by mercury from
the historic operations of 12 to 18 aills. These sills
discharged an estimated 14 to 15 million -tons of mercury to
the Carson River during their active life at the close of the
19th century; now, the tailing piles they left behind
P0ur>J,C
discharge an estimated 8 million-tene annually to the river
systea. The site poses a threat to huaan health and the
environment in various ways. Elevated levels of mercury have
been documented in surface water, river sediaents, and fish.
pete-
The tailing piles aay poet-a threat to nearby residents who
could inhale aercury vapors or meijury-contaminated dust. EPA
A
has no current evidence of contaaination in drinking water.
Surface water is presently used for irrigation of food crops
<*> i«tc
and forage. The site is used as a -winder habitat for the bald

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59
eagle, an endangered species.
It is-not- EFA's responsibility to conduct a search of
potentially responsible parties, or PRPs, to whom we would
assign responsibility for investigation and clean-up. We have
no information on the current status and viability of the
original mills. Under the Superfund statute, current and past
owners and generators are strictly liable.
Our next step is to undertake the legal research
regarding ownership, which we plan to begin in October of this
year. We will concurrently analyze options for immediate
stabilization and containment of the tailing piles, pending a
full site investigation. If our legal research identifies
viable responsible parties, we will undertake negotiations fo:
their conduct of the response actions needed. If viable
parties no longer exist at this site, EPA would respond using
available Superfund resources.
Inasmuch as & have several other sites in a similar
status ~ which is awaiting initiation of the response action
— due to resource constraints, we shall give this site our
serious attention, consistent with our mandate to address
worst sites first. Forthcoming actions at this site would
certainly include extensive coordination with the St^te of
Nevada and other parties, who have developed all of the key
technical documents on this site to date.
I would be pleased to respond to amy questions you may

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STATEMENT OF ALEXIS STRAUSS CORRECTIONS FOR PAGE 59:
Line Should read:
2	It is now EPA's responsibility to conduct a search of
17	Inasmuch as we have several other sites in a similar

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STATEMENT OF ALEXIS STRAUSS CORRECTIONS FOR PAGE 70:
Ling Should read:
4 talking about a solidification or a cement-fixation kind of an
6 feasible: Or we may be talking about controlling the drainage
8 hazardous vapors or other vapors that would affect people living

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71
October. I believe that ve will first have to go through thr
process of ensuring that there are no liable PRPs remaining.
Senator Reid. You start that in October?
Ms. Strauss. We would start that in October and at the
r
same time, what Z vould like to do is through -*<* emergency
response sort of a vehicle, find out if there is anything in '*
the short term that ve could do that the State agrees vould be
a useful thing to do with the tailings pilings themselves.
Senator Reid. Excellent.
Ms. Strauss. Assuming that ve find no remnants of viable
FRPs, then the next step vould indeed be the remedial
investigation. The tvo options that ve have there, assuming
no FRPs, will be EPA vill do the Federal	project or th*.
State may do it with money through the EPA. In California ve
had experience vith both and ve vill discuss it with DEP as to
-tU>\
vhat vro better in these situation/.
Senator Reid. Ms. Strauss, Z know this vould only be a
ball park figure, but as far as the time within vhich to
conduct the investigation after you have determined whether
there are responsible parties, do you have a ball park figure
as to hov long that vould take?
Ks. Strauss. Zf ve can assume that ve can quickly
conclude that the mining claims and the like lead us nowhere,
one can do this in a three to six-month time period. My
A	A
experience elsevhere is that sometimes it is not as clear as

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Carson River
Mining Waste NPL Site Summary Report
Reference 4
Memorandum Concerning Review of the Preliminary
Assessment for the Carson River Mercury Site;
From Bill Malloch, Ecology and Environment,
to Paul La Courreye, EPA; August 24, 1987

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ecology and environment, inc.
160 SPEAR S THEFT, SAN FRANCISCO. CALIFORNIA 94106, TEL. 415/777-2811
Intam«ten«l SoMKlati n rrm Envnnmani
MEMORANDUM
TO:
FROM:
Paul La Courreye, EPA Region 9 Site Screening Coordinator
William Malloch, Ecology and Environment, Inc.**7K.
DATE:	April 25, 1988
SUBJECT: Reassessment of Carson River Mercury Site
EPA ID#: NVD980813646
THROUGH: Chris Lichens, Ecology and Environment, Inc

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Reservoir. Mining operations that used mercury as an additive in the
amalgamation of ore left tailing piles near Brunswick Canyon and have
contaminated this portion of the Carson River. Pile information
Indicates that- an estimated IS million pounds of mercury escaped the mill
process during operation and vere either incorporated into the tailings
or vere discharged directly into the Carson River. Mercury has a high
Sax toxicity/persistence value. Mercury contamination in the river,
river sediments, and sport and commercial fish in the Carson River and
the Lahonton Reservoir have been documented. Sediment contamination has
also been documented up to 70 miles downstream of the Lahonton Reservoir.
The contaminated tailing piles contribute an estimated 8 tons of mercury
annually to the Carson River during the spring flows.
Commercial fish (blackfish) harvested from the Lahonton Reservoir are
transported and sold to restaurants and markets in the San Francisco Bay
Area. In 1983 levels of mercury in commercial fish exceeded the Food and
Drug Administration (FDA) level of 1 ppm. PDA sampling of commercial
fish in 1986 did not detect mercury above 1 ppm. Mercury levels in sport
fish are up to 8 times the FDA standards and health advisories have been
posted along the river and the reservoir limiting the amount of fish
consumed (one meal of caught fish per month). The Carson River and the
Lahonton Reservoir are not used for domestic vater supplies but are used
for the irrigation of approximately 80,000 acres, most serving livestock
(dairy and beef cattle) and approximately 250 acres for human-
consumption crops. The Carson River/Lahonton Reservoir watershed is a
habitat of the federally listed endangered bald eagle.
Sampling along the Carson River detected no contamination in the
groundwater, probably due to the low mobility of mercury in the soil.
Groundwater is used as a domestic water supply along the Carson River.
The groundwater target population is not currently known. There are many
residential developments along the banks of the Carson River and the
Lahonton Reservoir. Some of these developments are located within 0.5
miles of mercury-contaminated tailings and inhabitants could be exposed
to mercury vapors or mercury-contaminated dust.
The Nevada Department of Environmental Protection has performed many
studies concerning the widespread mercury contamination and is currently
participating in a Joint fish tissue study with the Nevada Department of
Vildlife and the FDA. No solutions have been offered and no funding is
currently available for remedial action.
The Carson River and the Lahonton Reservoir are owned by the State of
Nevada. The ownership of the area including the tailing piles is
currently unknown but suspected of being through mining claims.
RECOMMENDATION
1) EPA
FIT recommends a high-priority Screening Site Inspection (hSSI) be
conducted at the Carson River Mercury Site because the site could qualify
for inclusion on the NPL based on the following factors:
t/crm/para/wm

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o high waste quantity;
o high waste toxicity/perslstenee;
o documented surface water contamination;
o surface water target population due to irrigation of food
crops;
o endangered species located on-site; and
o potential air contaaination.
2) State or Other Agency
Copies of this reassessment will be sent to the Nevada Department of
Environmental Protection and the Nevada Departaent of Vildlife.
EPA CONCURRENCE	Initial	Date
No Further Action Under CERCLA 	 	
High-Priority SSI		 	
Medium-Priority SSI		 	
t/crm/para/wm

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Carson River
Mining Waste NPL Site Summary Report
Reference 5
Excerpts From Total Mercury in Sediment, Water, and Fishes
in the Carson River Drainage, West-Central Nevada;
NDEP; December 1985

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TOTAL MERCURY
IN SEDIMENT, WATER, AND FISHES
IN THE CARSON RIVER DRAINAGE,
WEST-CENTRAL NEVADA
James J. Cooper
• Richard 0. Thomas
S. Michael Reed
December 1985
Division of Environmental Protection
201 S. Fall Street
Carson City, Nevada 89710

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ABSTRACT
In the early 1970's cursory studies showed that Carson River sediment,
water, and aquatic biota contained higher than background mercury levels. The
source of this mercury has been traced to the Brunswick Canyon mills of the
historic Comstock Lode, that used the heavy metal to separate silver and gold
from the ore. Tons of elemental mercury were lost during the milling opera-
tions. Numerous mining companies have expressed an Interest 1n reclaiming the
mercury and associated precious metals from the riverbed. Without adequate
Information on the system, the environmental consequences of such an operation
have been difficult to define. The purpose of this study was to develop a data
base from which to draw Information to guide regulatory agencies 1n the future
management of the Hver system.
From Dayton upstream, surfldal sediment, water, and fishes have total
•mercury levels that are near or slightly elevated above background. The
transport of mercury via loading 1s also relatively low at Dayton. In contrast,
mercury in both the abiotic and blotlc components of the river sharply Increase
between Oayton and Lahontan Reservoir. Within this reach, spring runoff 1s
the primary factor controlling the downstream transport of the sediment-bound
mercury. Lahontan Reservoir, an Important fishery, receives a large annual load
from this upstream source. This load has a direct Influence on mercury bloac-
cumulatlon In the reservoir's fish population. Although Lahontan Reservoir 1s
now a sediment-mercury sink, the data suggests that large quantities of mercury
were transported past the impoundment before damming 1n 1915. Total mercury 1n
sediment, water, and fishes downstream of Lahontan Reservoir are considerably
higher than background throughout the Newlands Irrigation System, the Indian
Lakes Complex, and the Carson Sink.


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INTRODUCTION
Review of Carson River Mercury Problem
Since Roman times elemental mercury has been used 1n the amalgama-
tion process to separate gold and silver from ore. Large amounts of mercury
were used during the milling of the Comstock Lode near Virginia City, Nevada
1n the late 1800's. Of the 75 mill sites, the largest were located along the
Carson River 1n the Brunswick Canyon area due to the availability of water
power (Smith 1943). The "Washoe Process", as It was called, used 1:10
qu1cks11ver:0re 1n the amalgamation process. The average loss of quicksilver
was 0.68 kg for each ton of ore milled. During the 30 year peak of the
Comstock (1B65-1895) 1t 1s estimated that 200,000 flasks of mercury or 6.75 x
106 leg (7,500 tons) were lost 1n the milling process (Bailey and Phoenix
1944); about 0.5* of that amount was later recovered.
In recent years, few studies have been conducted to determine the
extent of mercury contamination In the Carson River system. It was not until
1971 that the U.S. Geological Survey (USGS) collected samples for mercury
analysis from sediment and water (Van Denburgh 1973). Background mercury
levels 1n the upper 7 cm of sediment upstream from pre-1900 milling sites on
the Carson River were 0.1 ug/g. Downstream concentrations were measured up
to ?00 times background (20 ug/g). The highest concentrations were found
just upstream from Lahontan Reservoir.
"Concurrent with the USGS study was one undertaken by the University
of Nevada-Reno, College of Agriculture Extension Service, which focused on
the accumulation of mercury by crop plants and domestic livestock. The study
found Insignificant bloaccumulatlon of mercury 1n these terrestrial plants
and animals (letter to Dr. John Carr, Nevada Health Division from Dr. Harry
Smith, University of Nevada-Reno, dated September 12, 1972).
R1 chins (1973) and Rkhlns and Rlsser (1975) were the first to docu-
ment that aquatic organisms 1n the Carson River system had levels of mercury
In muscle tissue which exceeded concentrations considered safe by the U.S.
Food and Hrug Administration (FDA). The study found that concentrations
-1-

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Even where mercury contamination 1s known, concentrations in natural
waters show surprisingly low values. Wershaw (1970) reported that In more
tha., one quarter of the water samples collected from sites at which mercury
contamination was suggested, no mercury could be detected at all and that
more than four-fifths of the samples contained less than 5 ug/1.
The absence of mercury 1n these natural waters 1s partially
explained by Its presence 1n sediment deposited downstream from mineral depo-
sits and Industrial waste outfalls. In a study to determine the distribution
of mercury 1n a polluted 4.9 km reach of the Ottawa River, Kudo, et al.
(1977) found that approximately 97% of the total mercury 1n the system was
associated with the bed sediment materials. They found the largest quan-
tities associated with organic matter and fines 1n the sediments. Blomass
Cf 1 sh - Invertebrates • plants) accounted for only 0.021, but this component
was the major source of organic mercury 1n the river. Lastly, the con-
centration 1n the water was very low compared to other components; however,
water played a major role In nercury transport and transformation.
Despite the fact that mercury 1s largely 1imob111zed In the sedi-
ment, aquatic organisms, especially fish, Ingest and concentrate enough mer-
cury to render them unsafe for food consumption In places where mercury has
been released to the environment (Annett, et al. 1975; Hoore and Sutherland
1980; Yamanaka and Ueda 1975). Furthermore, even after release has been
stopped, mercury continues to be available from the sediment. Based upon
laboratory experiments In Sweden, mercury may continue to be available from
the sediments for 10-100 years, possibly longer (Jernelov 1970).
Mercury exists In three oxidation states. The valence depends on
the redox potential, pH, and nature of the anions present (Gavis and Ferguson
197?). Mercury has a high affinity for sulfide 1on and forms a relatively
Insoluble compound. In aquatic systems where pH 1s likely to fall between 5
and Q and Eh - (redox) values are seldom higher than 0.5V, metallic mercury
and HgS are the species that will be present. At low Eh, which 1s present at
the bottom of eutrophlc lakes and deep river sediments, mercury ions are
effectively precipitated by sulfide 1ons (Fagerstrom and Jernelov 1971).
However, solubility Increases above pH 9 under reducing conditions.
-4-

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RESULTS AND DISCUSSION
Mercury In Sedtinent
Sediment and water samples tare collected for mercury analysis at 15
stations on the Carson River system. (Figure 1). Samples were collected from
May 1983 through December 1984 from the California state line to selected
sites within the Newlands Irrigation Project. Sediment samples were
collected from two categorical areas of the river channel. For one area,
samples were collected from the river bottom; material that 1s predominantly
underwater (Table 1 Figure 2). These samples were collected on 5 sampling
dates. For the other area, samples were collected from a mercury-rich
sediment layer above the river bottom that 1s underwater only during moderate
to high flows. This layer 1s easily located due to Its dark coloration and
1s likely a remnant of mercury-rich tailings deposited during Comstock mining
activity. Samples from this layer were collected on 4 sampling dates.
Upstream from New Empire and the Influence of the known ore milling
sites, background concentrations of total mercury were consistently below
detection (<0.25 ug/g). Mean concentrations of the sediment mercury steadily
Increased 1n the downstream, from 0.08 ug/g at New Empire to 5.44 ug/g below
lahontan Reservoir (Figure 2). Peak concentrations of mercurial sediments
were found below Lahontan Reservoir (14.66 ug/g), Weeks (6.55 ug/g), and
Chaves Ranch (5.00 ug/g). High velocities 1n Brunswick Canyon, where the
majority of nercury originally entered the river, have apparently eroded much
of the material from this reach to areas of less velocity downstream of
Dayton. The Truckee Canal, a transbasln diversion from the Truckee River
that enters the north end of Lahontan Reservoir, contains relatively low mer-
cury levels (I ¦ 0.12 ug/g) compared to Carson River sediments.
Although less systematic and lower 1n concentration, the five sta-
tions located In Lahontan Valley off of the main Carson River channel Indi-
cate that mercury 1s well distributed throughout sediments 1n the Newlands
Irrigation Project canal system. Concentrations ranged from <0.25 ug/g in
the "V" Canal at Sheckler Road to 2.45 and 2.49 ug/g In the South Branch
-9-

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TABli 1. Nean, range, and
river bottOB im
standard deviation of sedlaent imp Its
'MKury rtcft' layer. 1983 • Deceit
col 1 acted
«r 1984.
frgo tne

River Bottae

•lereury
-Rten* Lirir
Keen
Station location n (uo/ol*
Range
(ua/a)
Hean
SO n (uo/at
amge
iuq/Q)
£. Fort at River* lew
10
—
*
«
—
u. Fort at PayttuvlHa
«
—
4
«
—
CradlaOaugn Bridge
«
—
4
«
—
in Oaplre
a. 08
m - o.4o
0.18 4
0.24
*0 -0. SO
Brvnsutck Canyon
• Santiago Ruins
a.27
10 - 0.68
0.33 4
19.08
K0 *35.05
Dayton Bridge
o.n
0.3S - 0.97
0.26 4
0.65
M0 -1.35
Chaves Ranch
2.S7
0.91 - 5.00
1.49 4
$.24
1.72-10.00
weets
1.09
0.70 . 8.55
1.19 4
13.11
2.10-22.85
Truetee Canal
0.12
10 • 0.35
0.17 3
«
—
Below laftontan Reservoir
S.U
0.65 -14.66
8.08 4
1.78
0.80-2.65
'V Canal • Sheekler Rd.
0.15
« - O.SO
0.22 4
0.20
« -0.4J
Soutn Branch 9
Sheenlar Rd.
i.os
0.10 - 2.45
0.87 4
9.39
2.27-23.75
•1" Oram near
Fillgn Atr Station
9.74
O.SO • I.10
0.26 4
1.91
3.72-4.25
Still water Slough Cutoff
aoove Fraewin Fond
1.78
Q.8S - 2.49
0.65 4
4.89
I.25-6.75
Stlllwiter Point
Reservoir Outlet
a

4
«
—
* • • < 0.2S ug/g; K) «4i treated is « lero for eilcuUtlon of means.
-11-

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Carson River and Stillwater Slough Cutoff, respectively. The South Branch of
the Carson River was once the original channel that conveyed water to
southern parts of the valley and Carson Lake. This data suggests that
although lahontan Reservoir may serve as a sediment-mercury trap on the
system today, a large amount of mercury was likely transported past this
location before damning the Carson River by the Lahontan Dam 1n 1915.
Sediment samples were also collected from a "mercury rich", darkly
colored stratum that 1s located 1nmed1ately adjacent to the river (Table 1).
The layer could not be found at or upstream from New Empire. However,
downstream from Hew Empire, mercury levels within the layer were higher than
samples collected from the river bottom at S of 10 stations. (Figure 2).
Samples from the layer were consistently high at Santiago Ruins (X ¦ 19.08
ug/g), Chaves Ranch (X " 6.24 ug/g), Weeks (7 ¦ 13.11 ug/g), South Branch
(T - 9.39 ug/g), "l" Drain (X ¦ 1.91 u9/g), and Stillwater Slough Cutoff
(X ¦ 4.89 ug/g). The maximum concentration was 35.05 ug/g collected In
Brunswick Canyon near the Santiago Ruins. Mercury levels were roughly four
times higher In the layer than In samples collected from the normally wet
stream bottom.
X-ray diffraction and microscopic analysis of material collected
from within, above, and below the layer suggests that the mercury 1s asso-
ciated with fine-sands and silts sandwiched between coarser sands and gra-
vels. (Table 2). We speculate that the stratum may be a remnant of the
period of active milling on the river. The past century of erosion has
washed and deepened the river channel leaving the layer 1 to 2 feet above the
present river bed (Figure 3). Average to low flows either do not reach the
layer or are of Insignificant velocity to transport material from it
downstream. However, the greater depth and higher velocities of the spring
runoff likely have a significant influence on the physical suspension and
downstream movement of this material.
-13-

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Sediment mercury concentrations reported 1n this study are sinllar
to previous studies on the Carson River. Van Denburgh (1973) collected River
sediment samples that had mercury concentrations ranging frcm 0.04 ug/g to 11
ug/g. Five samples reported by Rlchlns and Rlsser (1975) ranged from 0.12 to
1.35 ug/g. Roth of the studies cited above documented that mercury levels
Increased 1n a downstream direction to lahontan Reservoir.
Other study results are also available for comparison. Shacklette
et al. (1971) determined the mean concentration 1n 492 soil samples from the
Western United States to be 0.083 ug/g. Studying stream sediments In the
United States, Pierce et al. (1970) suggest that levels exceeding 1.0 ug/g
nay be Indicative of contamination by mercury bearing wastes. The con-
centrations of mercury 1n bottom sediments of the Willamette River, Oregon
ranged from 0.02 to 0.38 ug/g (Rlckert et al. 1977). In a water quality
study of the Truckee River mercury levels ranged from 0.008 at Verdi to 1.44
ug/g just below the confluence with Steamboat Creek (Pacific Environmental
Laboratory 1979). Lastly, 1n the mercury polluted Wablgoon River 1n Western
Ontario, Canada, surface sediment samples varied 1n mercury concentration
from 0.59 to 18 u
-------
sanples collected by the U.S. Geological Survey 1n 1972 ranged In con-
centration from.5.3 to 20 ug/g (mean ¦ 12.4 ug/g) (Van Oenburgh 1973). Five
samples collected by the Desert Research Institute 1n 1980 ranged 1n con-
centration from 1.2 to 23 ug/g (mean ¦ 8.4 ug/g) (Cooper et al. 1983). These
previous studies were from single non-compos1ted samples and have a higher
degree of variability and are lower 1n concentration than values reported 1n
this study. It 1s possible that the extremely high 1983 spring runoff
Increased the loading and subsequently the concentration of mercury in the
Reservoir's sediments.
Mercury In Water
Mean concentrations of total mercury collected from the river water
column for the entire study are presented (Table 3; Figure 5). Levels were
relatively low at the three control stations located above the historic mill
sites. Of the 46 background samples, only 3 (7*} were above the 0.5 ug/1
detection limit; concentrations ranged from 0.7 to 1.0 ug/1.
Unexpected and surprisingly was the presence of low mercury levels
between flew Empire and Oayton, a reach where the majority of mills were
located. Of 44 samples collected only 4 (9%) were above detection. Mean
concentrations at New Empire, Santiago Ruins, and Oayton were 0.04, 0.1, and
0.1 u<]/l, respectively. Maximums at these three sites clearly increase 1n a
downstream direction and were 0.7, 0.8, and 1.5 ug/1, respectively.
"In contrast, some of the highest mercury concentrations measured
during the study were between Oayton and Lahontan Reservoir. Chaves Ranch
ranged from <0.5 to 5.1 ug/1 (X ¦ 0.9 u
-------
relatively ' low mercury concentrations 1n both sediment and water (van
Denburgh 1973; Pacific Environmental Laboratory 1979),
Below lahontan Reservoir mercury levels are similar to those
measured above Dayton (I ¦ 0.1 ug/1). Only 3 of 16 samples 1n that reach
(19%) were above detection and the maximum concentration measured was 0.7
ug/1. Two factors likely Influence mercury levels below the dam. Past stu-
dies on the reservoir have shown mean hydraulic detention time to be about 9
months (Cooper, et al. 1983); sufficiently long enough for substantial
settling of Carson River sediments to which the majority of mercury Is bound.
Measurements of water transparency during this work showed a consistent trend
of increasing water clarity with concurrent decreases 1n turbidity as the
river water passes through the Impoundment. Of sixteen samples collected
from Lahontan Reservoir near the dan only one (0.6 ug/1) was above detection.
In a synoptic survey of the reservoir on 2 May 1985 In which surface water
(1 n) was collected from the Carson River Inlet to the dam, only one of nine
sanples were above detection. Only the sample collected nearest the river
inlet was positive having a concentration of 0.5 ug/1.
The reservoir also Impacts the downstream characteristics of the
river. Extreme seasonal fluctuations 1n discharge such as those observed
upstream are reduced as a function of the reservoir's storage and release
operations. As a result, scouring spring flows have less erosive action on
the'physical suspension of mercury-rich river sediments.
Of the five sites located on canals and drains of the Newlands
Irrigation Project, two had consistently low and three had consistently high
mercury concentrations. Low levels were measured at the "V" Canal (X ¦ 0.2
ug/1) and Stillwater Point Reservoir outlet (I ¦ 0.1 ug/1). These sites may
be influenced by upstream settling impoundments; the Carson River Diversion
0am above the "V" Canal and Stillwater Point Reservoir above its outlet.
Only 7 of 32 analyses (22%) were above the 0.5 ug/1 detection Hm1t 1n
samples collected from these stations. Relatively high concentrations were
observed on the South Branch (X ¦ 1.3 ug/1), Stillwater Slough Cutoff (X ¦
1.3 ug/1), and 'V Orain (X » 0.7 ug/1). Of 48 samples collected from these
sites 35 (73*) were above the detection limit.
•20-

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Carson River
Mining Waste NPL Site Summary Report
Reference 6
Excerpts From Mercury in the Carson and
Truckee River Basins of Nevada, Open-file Report;
A.S. Van Denburgh, USGS; 1973

-------
QPEU FIVE
UNITED STATES DEPARTMENT 07 THE INTERIOR
CEOLOGICAL SURVEY
WATER RESOURCES DIVISION
K'iINcS
NOV 2" nr.
¦Un,V" cf Nev. . Rc,.;
KERCTJRY IH THE CARSON AND TRUCXEE RIVER
BASINS OP NEVADA
by .
A, s. van Denburgh
Prepared In cooperation with the
Nevada Division of Healch
Open-file ^poxt
* 1973

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SUMMARY
Upstream from major pre-1900 ore Billing*-In Che Carson and
Truckee River basins, "background" concentrations of coCal mercury la
che upper 1 to 3 lnchea of sand- to clay-sized stream-bottom sediment
are less than 0.1 ag/g,^ microgram per grand/). Downstream, measured
concentrations were as much as 200 dates che background level, firmest
.concentrations were gneounr»r*H T~expecEed at streamflows
greater than those of 1971-72 are: as much as 10-15 ug/1 or more at
2,000 cfs (cubic feet per second), and as much as 10-20 ug/1 or more
at 3,000 cfs. Elsewhere, expectable concentrations are much less
because the bottom aedlment contains much less mercury.
The mercury contents of water samples from 36 wells in the Carson
and Truckee bakina were all less than 1 ug/1, Indicating that mercury is
not a problem In ground water, even adjacent to areas where scream-bottom
sediment is enriched in mercury.
Limited data indicate that the Carson River above Lahontan Reservoir
and the reservoir itself contain only trace amounts of dissolved arsenic,
cyanide, selenium, and silver. Among 17 additional trace metals analyzed
for on four unflltered samples"from the river above the reservoir, only
six of Che metals were consistently present in concentrations exceeding
detection limits. Maximum measured concentrations for the alx metals
were:
1.	Micrograms per gram are equivalent to "pares per million." The term
"total" refers to all extractable forms of mercury. ,
2.	Micrograms per liter are equivalent to "pares per billion." The term
"total mercury" refers to all extractable forms, both dissolved and
associated with suspended sediment, for a whole-water (unflltered) sample.
-1-

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aluminum, >670 ug/1; Iron, 2,500 ug/1; manganese, 1,100 ug/1; molybdenum,
15 ug/1; titanium, 110 ug/1; and vanadium, 15 ug/1. Presumably, Che
detected metals were associated largely or almost entirely with the
suspended-sediment phase of the water samples.
Selenitsn and silver concentrations in sampled well waters from the
Carson and Truckee basins were uniformly low, with one exception--*
selenium concentration of 18 ug/1 for the water of a shallow veil south-
west of Fallon (Public Health Service lloic, 10 ug/1). The arsenic
content of 15 sampled well waters ranged froa 0 to 1,500 ug/1 (0 to 1.5 ppo),
with seven of the values greater than 50 ug/1 (the Public Health Service
limit).
INTRODUCTION
Prior to 1900, mercury was used during the milling of ores from
the Comstock Lode. Almost 15 million pounds of the mercury escaped
recovery (Staith, 1943, p. 257), with much of It being Incorporated 1q
the mill tailings. This report summarizes and discusses the findings
of a 1-year study of mercury and, to a lesser extent, several other
trace substances in'the water and related sediment of the Carson and
Truckee River basins, made by the U.S. Geological Survey in cooperation
with the Nevada Division of Health.
2-

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Carson River
Mining Waste NPL Site Summary Report
Reference 7
Excerpts From Reconnaissance Survey of
Ground-water Quality in the Carson River Basin;
NDEP; January 1988

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RECONNAISSANCE SURVEY OF
GROUND-WATER QUALITY IN
THE CARSON RIVER BASIN
JANUARY 1988
Kathy Sertic
Doug Zimmerman
Dan Gross
Division of Environmental Protection
201 S. Fall Street
Carson City, Nevada 89710

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Four water aupln wri obtained fro® the eurfece weter system,
following ona particular drainaga through tha valley from south to
north. Theee ssmplee were collactad to characteriza tha aurfaca
weter quality and potential degradation dua to impact of light
induatry, eewege effluent dlacharga, and agriculture. Sample aitaa
included Martin Slough behind tha Bantlay Manufacturing plant in
riindan (CU-MJ, rilddle Ditch at Mueller and Senoe Lanee CCU-3 and DJ-
5), and the ehannal Froa Ambroeettl Pond which drains to tha Carson
River CDJ-1D.
Each sample wee analyzed For etandard weter chemistry, total
nutrionta and traca aatale (Table 3). The Martin Slough saaple was
additionally analyzed For uOCe, but ehewed no detectable velums.
Analyoia reeulta indicate good quality eater with low total
dlaaolvad solIda CTDS) concentretlon. There la a general increase
in IDS, calclua, megneeium, eodlum, potaaelue, aulFata, chloride,
and arsenic through tha eye tee, but all constituents are below
applicable drinking weter etandarde. The eecondery drinking weter
standard For iron wea exceeded at Ambroeettl Pond. Comperleen oF
nutrient levels Fore Martin Slough through the ayatee to Ambroeetti
Pond showed that all concentratione are low. However, there ie an
increase in ell values except aeamnie Froa the Martin Slough alte to
the rtuller Lane site, which ie downgradlant Froe the MQSO efFluent
discharge point.
Sewapp EfFluent Disposal
Adequete sewage troetment end dlepoeel ie a major probl
facing communities within the Caraon River Beein. Repid population
growth incraeeee the demend For municipal traeteent of oewege, and
disposal of treated efFluent becomee lncreeelngly difficult. As
strict chemieal standerde for discharge to eurface watare ara
enforced by the State to maintain the integrity of surface waters
for downstream uaere, alternete methods of effluent dlapoeal muat be
found.
In the Cereon Uelley, e mejor eource of potentiel pollution to
the shellow ground weter eyetem end the hydrologlcelly connected
surface weter system Is dlscherge of treeted eewege effluent for
irrigation and land application. The treatment fecllltlee ara
required to eonitor and meet discharge atenderda for certain
constituents which ara moatly biologically releted parameters such
as BOO, dlseolved oxygen end fecal collform. While these are
important parameters, there ie growing- concern thet other
constituents, such ss trace metals and organic compounds, have the
potential to iapect the eyetem. Nltrete le probably tha conatltuent
of graateet concern with reepect to petantlel ahallow ground-water
contaminatUn. Nitrata lavele are important in ground watar because
elevated concentratione can cauae methemoglobinemia, a blood
disorder fetal to infante and cattle CAdem, 19803. Nitrite and
ammonia ara raedily oxidized to nltrete In the subsurfses by
nitrifying becteria. Phosphate levele are generally not a concern
- 11

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STUDY AREA
/
\ (
C4Aso» ; y
m.v1*' .•' UN* : t
¦OUNOARY OP>
CARSON RIVER
¦AS1N
4
¦
10 20 30 Mitat
120°
111®
Figure 1. Location Map of Study Area(from Welch and Plume, 1987)

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Stlf
Nu>b»r

Local1 on

Sit*
or Oanar
Dat»
Saapled
Typa of
Saapla
CftwiiJ
T1SN
R2IE
s s*
NH
Santiago
11/20/86
¦onltorlng veil
CRXjOS
T1SN
R2IE
5 SH
NN
Santiago
11/20/86
Carson River
CRn.i1
TI7H
R24E
32 NE
SH
Fort Churchill Cage
11/20/86
•onltorlng wall
CRmJIS
T17N
#24E
32 NE
SH
Fort Churchill Cago
11/20/86
Carson River
CRW22
Tlt.H
R22E
3 SE
HW
ho•11 02
CRM2 a
T16N
R22E
3 SE
MM
Alhaabra Mint
12/30/66
aonltoring
*•11 #10

TI6H
R22E
3 SE
HW
Alhaabra Hlna
12/30/66
¦onltorlnfl
wall «a
CRW30
T17N
R21E
23 NV
SE
Slat HI la Canyon
12/30/66

1 able
15.
Sampling Sites
from Brunswick Canyon to Lahontan Reservoir.
- ™ -
Weil Oapth
(feet I
f«rlor»t»d
Inttrvtla IItelI
Vatpr L«url
Fro* Top of Casing
I laat t
b	4-6	I
10	6-IO	3
79	37-77
200
120
120
63	31.3
53	2a.7
33	21 3

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OAYTON AND CHURCHILL UALLEYS
Gangral Ovrviatu
Dayton and Churchill Ualleys are the principal hydrographi:
areas in this segment of the Carson Rivar Basin. Brunswick Canyon
in tha upper portion of Dayton ualley, is the sits of the many mill:
used to process the ore of the Comstock Lode. In the lower portior
of the region, in Churchill Ualley, the Carson River was dammec
during the early 1900's to form Lahontan Reservoir, the main storagi
facility for the Neulands Irrigation Project.	•
The geology of the area is similar to that of the Carson ant
Eagla ualleys. Pre-jurassic to Quaternary age consolidated ignsous
mnr.Ainnrphie anrt serli mnnt.nrij rocks are overlain by unconsolidated t
semiconsolldated Tertiary to Quaternary age deposits of clay, silt
sand, and gravel. This alluvium may be separated by bedrock to far
independent or semi-independent valley fill resarvoir system
CGlancy and Katzer, 1375).
The sparse papulation of the region is mainly cantered arour
tha small towns of Dayton and Silver Springs, and a feu rura
subdivisions. Agriculture is limited, and is mostly focused alor
the narrow flood plain of tha Carson River. Contamination of grour
and surface water by mercury and cyanide utilized in mimr
processes was tha mam-focua of tha sampling conducted in
segment of the Carson River Baain. Sampling sites in this par.
of the river basin ara praaanted in Tabla CIS) and Figure CH).
Comstock nming Era
In the late lBOO's the milling of ore from the Comstock Loi
resulted in the disposal of large volumes of tailings which inciudi
an astimatad 7,500 tona of elemental mercury used in the milli
process. The main milling sitaa were located m Brunsuick Cany
due to tha availability of uatar power from tha Carson River (Coop
et al, 1985). Tha marcury laden tailings ware discharged direct
to tha Carson Rivar at tha Brunswick Canyon mills, rtany othar mil
uora located throughout tha Oayton-Uirginia City area and marcu
ladan tailing ara still preaant at theae sites. Eleveted marcu
levels have baan documented in Carson Rivar and Lahontan Reserve
sediments, and aquatic biota CUan denburgh, 1373, and Cooper et a
13B5).	'
*
Eleveted concentrations of mercury ara not usually detected
ground water, due to its high affinity for adsorption on silt b
clay particles and organic material. If marcury contamination ^
ground uatar la occurring tha mostly likely location to encount
such contamination would ba in tha saturated zona which is in din
contact with marcury rich sadiments.
- 3S -

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*o
rn
in
>-4
H
rn

I
CO >4 c (jJ 5j
k
Ut-^V;
«'i^/ i r
e ''Zl.-' l^' W''\'k - '
^Kf'!'!':i#
Figure 4. Sample Site Locations From Brunswick Canyon to l.ahontan Reservoir,
(base map modified from Clancy and Katzer, 1975)

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To uina thla possibility the NDEP instslled shallow
Monitoring Mils at two location* along the Caraon River. Xfea
Santiago Ruins CCKW20) waa a former aill aita and tha USQS F
Churchill aita CCSW21) la 1ocatad down gradiant fro* ail Former
mills and la in an araa of documented high mereury concentration.
Both ground watar and aurfaca water saapla* Mara collactad at thaaa
sitae. Analytical raaulta aho—d no alavatad mercury 1avala in arv
of tha sampiea CTabla 16). Both ground watar aaaplaa had alavatad
1avals af iron and aenganeee. It is euepeeted that tha taillnga mag
ba tha aourca of thaaa eleaenta.
Thraa othar altaa wars aeapled to further avaluata aourca*
rolatad to Coeetock nining activitiaa. Sample CXV2S waa collactad
from a doaaetlc well 1 oca tad in tha flood plain of tha Caraon
Rlvar. Elavatad aarcurg lavala hava baan doeuaantad in aedimenta ut
this slta CCoopar at al 1385). Analgaia raaulta of tha ground watar
aampla ahowad no alavatad aarcurg concantrationa CTabla 16).
Saapla CRW86 wae collactad fora Sutra Tunnal which waa
axcavatad through tha Virginia Range during tha Coaatock ara to
provida drainaga for ground watar sneountarad in tha daap aina
shafta. Watar la not currently puapad froa tha aina ahafts, however
thara la dlacharga of ground watar froa tha tunnal. Anelyeia
raaulta showad alavatad aulfata and manganeee lavala CTabla 16).
The last sample collected CCRW30) was froa the aurface atream
in Six fills Cangon. Thla canyon axtanda into Uirglnia Citg end has
abundant evidence of mining activates. The source of water in Six
Hi la Cangon la in part derived froa the aewage troataent plant
Uirglnia Citg. However, analgaia reeulta ahowed no detects,
nitrataa in the saapla which indlcatea that the trsstment plant
discharge mag be a minor component of the total flow in Six nil*
Cangon, at laaat at tha point of sampling. Comparison of overall
chemistrg between thla aampla and tha Sutro Tunnel saapla auggesta
that the majority of flow mag be derived froe ground water dlacharga
into Six nila Cangon (Table 18).
ftlhambra nine
The Alhaabra nine, whieh began operating in December, 198H, la
a raprocaaaing project utilising a cganidation leaching process to
rscover gold, silver end aarcurg froa tha mill taillnga of the
Comotock era. The recoverg proceaa waa terminated in Julg, 1986, but
the coapang has been required to weeh the telling hesps until the
rinsing watar* hava a pM of <8.5 and tha cyanide level la <2 mg/l.
Tha operation la altuatad on tha flrat terrace above the Caraon*
Rlvar. A number of prlvata residences are located downgradlent of*
the aita, between the aita and the river. The Mine periodically
samplea tha aita monitoring welle and nearby domestic wall*, and
anaiyzea for pH, conductivity, mercury, and cyanide. The monitoring
walla are constructed of 6 inch diameter PUC caaing and extend 10'
faat into the aaturated zone, for thle aurvey, NDEP sampled thraa
of tha eleven aita monitoring welle, *6 CCRWS7), S8 CCRWS9), and «10
CCRWEB), and aeveral downgradient domaatlc wella in December, 19^
- 38 -

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Raportlnq
Unit*
CRM20
Sant laqo
ground aalar
CRV20S
Santlaqo
Carmn liver
CRM 21
Ft. Churchill
qrnund vatar
CRN2IS
Ft. Churchill
Caraon Rlvar
CHH2C
CRH30
Sla Htla Canyon
CRN7S
Cha««s Ranch
¦ I
ol
(In
rl
standard unit*
uahoi
PlaioUnl »a/l
Ida at 103-C
f •
ni
I >i
I u
on
I r-
raa
¦ a
al ua
a
a lua
ta
Ida
la
I n 11 f
banal¦
nal a
I dr
I c
¦ IfurnacaI
-	do -
-do-
-do-
-do -
-do-
-do-
-	do -
-do -
-do-
-do-
-do -
-	do -
-	do -
-do-
-	do -
-	do -
-	do-
-	do -
-	do -
-	do -
-	do -
11/20/06
7. 16
700
SO
307
so
20
46
4
217
21
0.6
140
101
O
O. 30
0.014
6. 36
3. lO
O.OI
0. 39
O. 20
O. 22
O. 2
26
I I/2O/06
0. lO
341
213
97
29
6
27
3
SO
lO
2. 4
102
124
O
O 39
O. 007
O. 23
O. 04
O. OO
O. OO
O OS
O. 07
O. 2
24
ii/:o/06
¦>. i«
bis
400
211
63
13
SO
2
34
16
0. O
270
339
O
O. 7H>
O. 030
0. 63
S. 40
O. Ol
O. 41
O. O0
O. OS
O. 3
to
I I/20/86
7. 71
406
253
1 2 J
36
a
2 j
4
66
a
2. 6
I 12
137
O
O. 4 3
O. OO0
O. 62
O. IO
O. OO
O. 03
U. Ofc
O. 06
O. 2
24
12/29/66
7. 73
1429
1133
Ol
214
30
C0
3
613
7
O. O
210
266
O
O JO
«0. 003
0.	07
1.	09
O. OO
O. 01
O. 03
O O
36
I2/30/S6
8. 20
1361
lUHb
604
193
49
34
2
SSO
20
O. O
232
239
22
O. J0
«0.003
O. 06
O. 06
a. oo
a. oi
a 03
O. 04
O. I
27
I 2/29/86
7.SO
MO
161
0.011
• I ua
<1— | ua
<1
cur f
en I urn
•q/ I
-	do -
-	do -
-	do -
-	do -
-do-
<0 OOI
«0.OOS
<0 OOS
«0.OOOS

-------
The cltu of Fallon la the Mln papulation center with about
5000 paopla (Welch and Pluae, 19B7). The raat of the approxlaatal'
9000 inhabltanta ara apraad over tha agricultural dlatrict. TT
U.S. Naval Air Station la a flight training facility which Maintains
a large nuaber of jets and othar aircraft, tfslls to aupplu tha cltu
of Fallon and tha Naval Air Station panatrata tha baaalt aquifer,
while moat privata doaaatlc aalla ara aaplacad In tha ehellow and
lntermadlata aqulfara CBlancy, 1906).
Stillwater wildlife flanagaaant Araa la a aajor braadlng grounda
and atopovar for hundrada of thousands of birds algrating, on tha
Pacific Flyway. Water for approxlaately 144,000 acraa of aarahaa,
opan aallna water, and fraahaatar wetlanda la auppllad froa
irrigation return flow. Llttla fraah watar raplanlahaa tha refugeu
aa aoat Caraon River aatar has baan allocatad for Irrigation.
Recant flah and bird kills In tha Carson Sink hava baan attributed
to increased aallnizatlon of tha watar, and possibly Increased
auscaptlblllty of tha wildlife to dleeaaa due to elevated levala of
potentially toxic eleaanta auch aa araenlc and aeleniua.
Within tha Carson Dsssrt. tha aaln focua of thla eurvey was on
the potential lepact of agricultural practicaa on the shallow
aquifer. Tha saapllng prograa was dsalgned to characterize tha
quality of Irrigation water, Irrigation return flow and ahaHow
ground water. Potential ground-wetar quality problaaa addrssaad
includa elevated arsenic and aeleniua levele, nitrate contaainatlon
froa fertilizers, llvsstock, and saptlc systaas, high salinity
affecta reaultlng froa Irrigation, and the presence of peatlcldae in
ground wstsr. Non-agrlculturslly raletad sources of eontsalnatlr
to tha shallow aqulfar ayatea In tha PalIon araa Includa laakii
underground atorage tanke, light induetry, and actlvltiee at tha
U.S. Naval Air Station. A auaaary of the aaapling aitaa in the
Caraon Oeeert la preaanted in Table CIS).
Canal. Drain, and Shallow Around Mater-Qualltu
The overall aaapling approach to characterize the quality of
irrigation water, irrigation return flow and ahe1low ground water in
the Newlande Xrrlgetlon Project end the potential lepact of
agricultural practlcee on the anallow aquifer, Involved ssapllng
along one of the aaln Irrigation watar distribution and rsturn flow
systems, the L Canal and L Drain ayetoa. Shallow ground watar wea
sampled froa monitoring walls near the drain sgsteas. In irrigated
fields, end froa eubeurfaca dralne et tha Agricultural Experiment
Farm. The aaapling altae ara indicated on Figure (S3.
The L canal and L drain ware aaapled near tha heed of the
syatom, and tha L drain waa aaapled at three subsequent down
gradient altae. To aaaple the ahallow ground weter, hand driven
wallo were eaplaced into the ehellow equlfer at altae adjacent to
the drain aaapling polnta. These welle ere conetructed of l.S inch
diameter galvanized pipe with factory acreened well points.
- 44 -

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Carson River
Mining Waste NPL Site Summary Report
Reference 8
Personal Communication Concerning Carson River Mercury Contamination;
From James Cooper, NDEP, to Bill Malloch, Ecology and Environment;
May 10, 1988

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Ref:rir.:c
Site Msrr.o lutein (?inrffl'nif\nhiiHr
EPA ID #		 Reference 2
CONTACT REPORT
AGENCY/AFFILIATION: Nevada Department of Environmental Protection
DEPARTMENT:
ADDRESS/CITY: 201 S. Fall St.
COUNT!/STATE/ZIP: Carson City, NV 89710
CONTACT(S)
TITLE
PHONE
1. Jim Cooper

(702) 885-4670
2.


B & E PERSON MAKING CONTACT: Bill Malloch
DATE: 5/18/88
SUBJECT: Carson River Mercury Contamination
SITE NAHB: Carson River Hercury Site
EPA IDt: NVD980813666
Tailings piles adjacent to the Carson River begin near Brunswick Canyon and are
scattered along to Dayton, Nevada. Additionally, tailings piles are located up
Six Mile Canyon and across the Carson Plains. Soae piles are located vithin 0.5
miles from residental areas. Piles are located in the Carson Plains have levels
of mercury up to 500 ppm. These piles are vaste material from the "Vashoe
Process" and have never had any type of containment.
Annual rains carry an estimated mercury load of eight tons from the tailings
piles from the Carson Plains and Brunswick and Six Hile Canyons to the Carson
River. The highest levels of contaminated sediments and vater exist in areas of
lover flov where the contaminated sediments are deposited.
In 1985 a "mercury-rich" layer of sediments located in the dry wash areas of the
Carson Plains and approximately 1 to 2 feet above the Carson River was
identified. This layer is thought to have formed from years of sedimentation.
The floods of 1986 washed this layer back into the Carson River.
Limited air sampling has been performed over the tailings piles. The sampling
was performed using a portable instrument sensitive to mercury vapor. Sampling
was performed on a warm day (85° F) degrees and mercury vapors were not
detected.
However, after tailings samples were microwaved, the portable instrument meter
vas pegged. Sampling should be performed for mercury vapor on a hot, calm day,
and for particulate dust on a windy day. The Carson Plains get temperatures
over 100 F and wind gusts up to 40-100 mph.
t/cariv/hrs/jan

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Carson River
Mining Waste NPL Site Summary Report
Reference 9
Excerpts From Water Resources Appraisal of the Carson River Basin,
Western Nevada, Water Resources Reconnaissance Series, Report 59;
Nevada Division of Water Resources; 1975

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Lahonton Dam ipillvar in tarty lummir of 1969.
WATER RESOURCES-RECONNAISSANCE SERIES
REPORT 59
WATER-RESOURCES APPRAISAL OF THE
CARSON RIVER BASIN, WESTERN NEVADA
By
Patrick A. Glancy
and
T L. Katier
Prepared cooperatively by the
Geological Survey, U S. Department of the Interior
1975

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The ground-water systems of the larger valleys in the report area are
complex in that several aquifers may exist at varying depths and within local-
ized geographic areas. These various aquifers, although collectively part of
the valley-fill reservoirs, ray act semi-independently of each otheT with
regard to their individual hydraulic characteristics. For example, Walters,
Ball, Hibdon, 6 Shaw (1970, p. 16 and 23) recognized two distinct zones, or
aquifers, in Carson Valley alluvium, which they refer to as a shallow zone and
a deep zone. They note a lack of any continuous confining strata between the
two zones as indicated by well-drillers' logs, but recognize that partial con-
finement of the deep zone by an apparent overlapping of various clay lenses
causes static water levels of the shallow and deep zones to differ. There aTe
several flowing artesian wells in Carson Valley.
The ground-water reservoir of Carson Valley is believed to be the most
important in the study area because it contains large quantities of good-
quality water.
Occurrence and movement of ground water in Eagle Valley are discussed by
Worts and Malmberg (1966).
The several valley-fill reservoirs unique to Dayton Valley have already
been briefly described in the report section dealing with extent and boundaries
of the valley-fill reservoir. Hydraulic heads in these valley-fill reservoirs
generally range from a few feet above to several tens of feet below the land
surfac< (table 39). Ground-water movement is generally toward the river in the
three upstream systems. Movement of water through the valley-fill deposits
that include the Stagecoach Valley subarea is less certain, because available
data are inconclusive regarding hydraulic continuity between Stagecoach Valley
alluvium and Carson River alluvium to the south. Natural phreatophyte discharge
of ground water and existence of an alkali-flat playa in Stagecoach Valley, plus
the presence of a gently sloping divide of subdued relief and possibly thin
alluvial cover between that valley and the Carson River flood plain, suggest
Stagecoach Valley may be hydraulically isolated from the Carson River. However,
water-table altitudes beneath the playa and at the river are similar, suggesting
a good possibility of hydraulic continuity between Stagecoach Valley and the
Carson River. Resolution of this uncertainty is beyond the scope of this
investigation.
No long-term records of static water levels are available for Churchill
Valley; however, it is assumed that the filling of Lahontan Reservoir has caused
a general rise in ground-water levels throughout much of the valley since 191S,
when the dam was constructed. Ground-water levels measured in June 1970 in the
vicinity of the reservoir were all within a few feet of the reservoir surface.
The regional ground-water flow system in the Carson River basin above
Lahontan Dam is generally downstream toward the reservoir and is mainly controlled
by the surface-water altituae. Katzer (1972) stated that some water probably is
seeping from the reservoir through volcanic rocks and associated alluvial deposits
that are present in the eastern subsurface of the reservoir in the vicinity of
the dam. The magnitude of any subsurface leakage is unknown but probably is
minor compared to surface-flow releases.
-15-

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Carson River
Mining Waste NPL Site Summary Report
Reference 10
Excerpts From Remedial Investigation Report,
Silver Mountain Mine Okanogan County, Washington:
Volume 2 - Appendices, Draft; EPA; December 15, 1989

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REMEDIAL INVESTIGATION REPORT
VOLUME 2 - APPENDICES
SILVER MOUNTAIN MINE
OKANOGAN COUNTY, WASHINGTON
Draft
December 15, 1989

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Inorganic mercury (Hg*°) exists either as the faniliar metallic liquid,
or as mercury vapor. Environmental exposure to mercury vapor is relatively
unimportant, the main exposure source being occupational. Important in this
regard are chlor-alkalai plants, manufacture of electrical equipment, paints
and thermometers, and uses associated with dentistry.,44, (99} When
ingested, little if any liquid inorganic mercury is absorbed from the gut, the
material having even been used historically as a therapeutic aid for
constipation relief. However, metallic mercury volatilizes easily at ambient
temperatures. This vapor is easily diffusable across alveolar membranes and
is sufficiently lipid soluble so as to have affinity for the CNS, red blood
cells, and other tissues. While briefly dissolved rn blood prior to being
oxidized to the divalent form, it will readily cross the blood/brain and
placental barriers, About 80 per cent of mercury vapor inhaled by the lung is
absorbed, and the bioavailability of volatilized metallic mercury is therefore
great. Transport across skin is not well known, but probably occurs to some
extent. Halflife in the whole body is about 50 days, with halflife in blood
somewhat less, and highly variable. Distribution is mainly to the kidney, and
to red blood cells, where, acting as a substrate for catalase enzyme, Hg.0
is oxidized to the divalent mercurous form (Hg*2), which can no longer so
easily cross biological membranes, especially with respect to the brain.
Excretion of inorganic mercury acquired as vapor is mainly via urine and
feces, with small amounts excreted via sweat and saliva.(44) (99)
Inorganic mercury salts may be either monovalent (mercurous; Hg*1), or
divalent (mercuric; Hg*2). Mercurous salts have enjoyed minor medicinal
uses, and include calomel. They have also been used in the past as a
component of teething powder. Mercurous salts are poorly absorbed, and
readily oxidized to the mercuric form in the body. Mercuric salts include
Hg2Cl2 and HgO, and have been used in the past in the felt hat industry,
where they gained special notoriety in eliciting "mad hatter" symptoms of
poisoning. Current uses include mercury storage batteries and detonators.
Mercuric salts are only absorbed at about 10 per cent orally, and are about 40
per cent absorbable from inhalation of fumes from mercuric salts (ala the "mad
hatter"). Distribution of mercuric salts is mostly to the kidney, which is
the main site of inorganic mercury accumulation in the body. Excretion of
mercuric salts is similar to metallic mercury.(44)< <99)
Organic Mercury: Of greatest importance to this group toxicologically is
methyl mercury, which is environmentally obtained mostly from fish. The major
source of methyl mercury in the environment is via microbiological conversion
of inorganic mercury by methanogenic bacteria in sediments of aquatic
ecosystems. Environmental situations such as "acid rain" also favor the
formation of methyl mercury over less toxic alkyl forms such as the ethyl
species. Methyl mercury is also a by-product of the plastic industry (e.g.,
in Japan, where contamination of Minamata Bay resulted in extreme toxicologic
problems in the late 1960s). Klaassen, et al (1986q) (99) report that
methyl mercury was first synthesized in 1860 London, by two chemists who
subsequently died from the cumulative effects of their labors. Methyl mercury
has been used in the past as a fungicide dressing for seed grain, but this use
no longer occurs. Exposure to other organomercurials can occur from paints,
where phenylmercury is used as a fungicidal additive, and from contraceptives
where it is employed as a spermacide. In the past, certain organomercurials
have enjoyed therapeutic uses as diuretics, but there is little or no such use
today. Short chain alkyl mercurials are 90 per cent absorbed from the GI
tract, and easily cross the skin barrier. Once absorbed, they are highly
22

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mobile in the body, readily crossing into the brain, as well as into the
fetus. As in the case of lead, concentrations in red blood cells are about
tenfold those of plasma. Organic mercury is very slowly broken down into
Hg*2, about 90 per cent of which is excreted in the feces. An
enterohepatic cycle is involved, in which it first undergoes biliary secretion
into the gut, where it is then converted by intestinal microflora to the
inorganic Hg++. This excretory process ceases if the intestinal flora are
inhibited (e.g., during penicillin therapy). Halflife in man is about 65
days.(99)
Acute mercury poisoning can result in both local and systemic effects.
Local effects from the ingestion of (chiefly) inorganic salts include:
gastrointestinal (pain, vomiting, hemorrhage, diarrhea), respiratory
(pneumonitis, metal fume fever from Hg*°), and dermal (skin blisters from
phenyl Hg). Systemic effects include shock, nephrotoxicity due to inorganic
salts, CNS symptoms which include lethargy and shock related effects, and
other problems including sore gums, metallic taste, and salivation.(44, {99)
Chronic effects of mercury poisoning are complex and variable, but focus
largely on CNS and kidney as prime target organs. Chrome mercury vapor
* poisoning involves effects on the CNS (e.g., "mad hatter" erethism-- which
includes neurologic problems, shyness, and memory loss—and tremor), the
kidney (proteinuria and enzymuria), the "oral cavity triad" (gingivitis,
salivation, stomatitis), and occasionally other manifestations such as
mercurialentis of the eye.(ii>
Chronic inorganic and metallic vapor poisoning is somewhat reversible,
but chronic poisoning from methyl or ethyl mercury is usually irreversible
because it typically involves a large degree of specific damage to neurons
Chronic poisoning from methyl or ethyl mercury in the adult usually involves
paresthesia, visual field constriction, hearing loss, dysarthria, and ataxia
The latter symptom is due specifically to a loss of granular cells in the
cerebellum. In the fetus, chronic methyl /ethyl mercury intoxication leads to
psychomotor retardation and cerebral palsy as a consequence of abnormal brain
development. Chronic effects of exposure to inorganic mercury are not well
documented, but the kidney is the suspected target. Chronic phenylmercury
exposure results primarily in nephrotoxicity, with mild enzymuria.(4t) (99)
Diagnosis of poisoning from mercury vapor and inorganic mercury salts is
largely via symptoms, exposure history, and urinary levels in excess of 20
ug/1. Tremors are evident at urinary levels in excess of 500 ug/1. For
methyl mercury, early diagnosis of neurological signs and symptoms is
difficult. A dietary history (fish, etc,) is essential. Normal blood levels
are less than 20 ug/1, with symptoms occurring at about 200 ug/1. Normal
levels in adult hair are about 1 ppm, with symptoms evident at about 50
ppm.(99) Classic treatment for mercury is via dimercaprol (SAL) chelation
therapy. However, BAL cannot be given orally, has side effects, and although
useful for protection against kidney effects (Hg*2), it is ineffective for
protection of brain (Hg*°, CHjHg*).(99) Oral penicillamine is more
effective for Hg*°, while oral administration of dimercaptopropane sulfonate
(DMPS; a newer derivative of BAL)) is more effective for organic as well as
inorganic forms.(44)
At this writing, EPA has not established a Rfd for inorganic mercury. In
terms of carcinogenic risk, EPA /IRIS (1989x) (202) has classified inorganic
23

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Carson River
Mining Waste NPL Site Summary Report
Reference 11
Excerpts From Total Mercury in Fishes and Selected Biota
in Lahontan Reservoir, Nevada: 1981; James Cooper,
Bulletin of Environmental Contamination Toxicology, 31:9-17;
1983

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Bull fcnvtion Coniam Tovnol )> 9-17(1983)
O 198) bpiiR|(i Veilj| New Vcuk Inc
Total Mercury In Fishes and Selected Biota In
Lahontan Reservoir, Nevada: 1981
James J Cooper
8
-------
kaveh of mercury In (he Muscle tlsiue which CNCceded concentre*
iIoa> considered	by (he 0 S food and Drug A found dtirlng Ihlt tludy to pest ttwdlet conducted
om the lyicee.
SIUOT SITC
lehonten lUufvoIr, located }1 km toutbeast of Heno# wet
created In 1915 when the Carton River wet Impounded for the
towlands Irrigation Project. The retervolr receives the entire
flow of the Carton River wtilch averaged 3 26 X 10* a1 (26t,000
t-ft I per yeer between I9U end t)?0 tUI2[l 1970 Weter It
diverted from the fruckee River to Iehonten fteiervoIr end the
Certoo River 0e>ln by wey of the Iruckee Cenel thet since I96H het
•applied en everege of 2 10 X 10* m* (l^&.SOO e-ft ) annually to
Um le^oundment or »pproite«ie)|f HO percent of the yeerly coolrI -
bet Ion Other Morphologic end bydrologlc cherecter1st let of the
fm*er vol r ere presented (Table I).
fable \ Morphologic end hydrologlc character!*!les of Lehonien
Reservoir* ftaved*.
OMrecterlttlc
Velue
Rtileoi length	27 km
Nului width	4
Mewl depth	26 m
«M» depth	B l m
Smrfece area	*,*10 he
Iwey elevation	1,269 m
C«P*cl»» j S; i'io* .»
Mydrtullc retldence tine	0 77 yrt.
iehonten Reservoir. In addition to ttorage of Irrigation
Miter, It elto used extensively for recreation Ihe retervolr hes
bvcome One of the aost heevfly used recreation ereet In northern
to**de end It within the Mavede Stele Perk Sytlem
10
Codftr
htlHOOS
During the summer of I98I fish were collected for analysis
using a verlety of mI hods Including gill netting, beech seining
end dip netting freshly collected flth were measured for length
end weight before being pieced on Ice, trensferred to the lebore~
lory In Reno end froren
Cold vapor atomic ebsorptlon wes selected es the enelytlcel
technique (or determining mercury concentreiIon In the fish tissue
Procedures followed were developed by SltWARI (1977) ApproalMte*
ly 10 g of muscle tissue was taken below the dorsel fin end ebove
the latere) line end macerated In i tlttue grinder Well spec let
or young-o(-the-yeer were matereted whole efter removal of the
viscera Liver end heerl tissue, pooled by tpeclet, were prepered
similarly. Ihe wet (Ittue wet weighed, lyophlllfed end rewelghad
to determine percent moltture content Ihe dried sample wet then
ground to e powder with e sorter end pettie end weighed In e teflon
parr bomb cup with 2 $ ml concentrated HNOy, I 0 ml of JO percent
H}0] end 25 e) Rf$?0f the temple wet then dlgetied In e perr
bomb for B hourt et 100-110 C
Recovery tludlet ipUed prior to dlgettlon averaged 92 percent
Retultt ere pretented et Ihe concentretIon of totel mercury per
wet weight of tlttuft Verlatlon between flth groupt wet enalyied
utlng e one-way analytlt of verlenco with unequal temple tliet
(KOM 1971).
RtSUL TS AND DISCUSSION
Retultt Indicate thet tlgnlflcenl mercury eccumuletlon Is
occurring within flshet of Lehonien Retervolr (leble 2) Mercury
concentretlont In mutcle tlttue collected from II species renged
from 0 II mg/kg In young-of-the-year white bett (Morone ohryeope)
to 9 52 mg/kg In e ttrlped bett {Morons eoxacilte) with e known
retldence time within the weierbody of 16 yeert (COOPfR i VICC
In prett) Of 53 *ftcle tlttue templet enalyied 36 (681) exceeded
the 1 mg/kg "action level*' considered tafe by the FOA Heart tit*
tue ranged from 0 17 «g/kg In carp (f^prtnue oorpto) to 5 56 mg/kg
In ttrlped bett. liver tlttue wet contlttently higher than heait
tlttue end ran9cd from 0 21 mg/kg In brown bullhead {lataluruB
nsbuloBhtm) to 2) 65 mg/kg In ttrlped bett Ihese levels represent
retlduet which ere conslderebly higher then the 0 20 mg/kg con»ld~
ered at background for fish (0*ITRI 1972) (reyflsh (Aut/aetooui
tp.) end California teegull (Larue aahforniau*) elso exhibited
eleveted totel eercury concentretlont
In generel Mercury concent ret Ion within species Increesed
with fish weight. A tlgnlflcenl positive correletlon wet found
between flth weight end mercury mutcle concentration for yellow
perch (Peroa /laueeaene) (r-0 62, P <0 05), while crepple (Ponorx«
annularte) (r-0 Bj, P <0 01), white catfish (lalalurus oatus\ (r-
0 66, P <0 05) end while bass (r-0 85, P *0 01) The other *p«cl*»
II

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Carson River
Mining Waste NPL Site Summary Report
Reference 12
Job Progress Report Concerning Carson River Contamination and Endangered Species;
From Mike Sevon, Nevada Department of Wildlife,
to Bill Malloch, Ecology and Environment;
May 18, 1988

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JOB PROGRESS REPORT
State:	Nevada
Project No.: F-20-22	Project Title: Statewide Fisheries Program
Job No.:	102	Job Title: Lahontan Reservoir
Churchill - Lyon Counties
Period Covered: January 1, 1986 through December 31, 1986
SUMMARY
Due to late winter storms and resultant high spring runoff in
the Carson River, Lahontan Reservoir spilled in 1986 from March 10
through April 24 and again from May 29 through July 27. Maximum water
level fluctuation in 1986 was 20.53 feet.
From May through September during 18 days of creel census,
1,392 anglers were contacted and reported expending 3,742.6 hours to
capture 3,228 fish for a success rate of 2.32 fish/angler and .862
fish/hour. White bass composed 85.56 percent of the creel. Other fish
species in the creel in order of abundance include: black bullhead,
white catfish, channel catfish, yellow perch, white crappie, walleye and
largemouth bass.
Length-frequency analysis of creeled white bass which are
dominated by the 1982 year class indicate no increase in size of white
bass from 1985 to 1986. Although gill net surveys indicate increased
catch rates for walleye, angler success for this specie suffered a
dramatic decline from 1985 to 1986.
From March through June, 402 net hours were accumulated in 22
gill net sets. A total of 203 walleye were captured to document spawn-
ing status. Spawning periods for major fish species were correlated
with water temperature data collected at two sites on Lahontan Reser-
voir. Prespawn walleyes concentrated at Lahontan Dam reaching maximum
densities on March 14. By April 10, all mature female walleye captured
in nets were spawned out.
Beach seining data collected in July and August documents
improved recruitment over the period from 1983 to 1985. During 1986 in
four days of seining and 1,730 yards of seine hauls, 2,938
young-of-the-year (YOY) fish were sampled for an average yield of 1.70
YOY per yard of haul.
Hydrolab profiles in the forebay of Lahontan Dam were moni-
tored monthly from June through September. Data collected from June
through August demonstrate an increase in oxygen deficiencies through
the sumner. Regardless of these deficiencies, water discharged through
the outlet conduit to the bowl maintained dissolved oxygen levels
exceeding 10.5 ppm. Water temperatures of Lahontan Reservoir outfall

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Range in Mercury	Long Term Consumption
Concentration	(ug/g) Recommendation
0-.5	6 meals/month
.5-.6	5 meals/month
.6-.8	4 meals/month
.8-1.4	3 meals/month
1.4-2.7	2 meals/month
2.7-3.2	1 meal/month
Using known mercury levels of Lahontan Reservoir game fish and
the long term fish consumption categories from Minnesota's program, a
fish consumption chart was prepared and distributed to Nevada Division
of Environmental Protection and the Consumer Health Protection Services
on January 23, 1986. In subsequent meetings during the spring of 1986,
personnel from Nevada Division of Environmental Protection, Consumer
Health and Nevada Department of Wildlife reviewed the fish consumption
chart with a general consensus that while the chart provided the best
available information on a specie to specie basis the chart was too
complex and would be confusing to the general public. On April 9,1986,
Nevada Department of Wildlife and Consumer Health Protection Services
resolved the fish consumption advisory which would be issued for the
1986 fishing season. The advisory states:
"The State Division of Health has determined from a study
completed by the State Division of Environmental Protection that a
public health problem exists from eating fish from the Carson River
(below the town of Dayton), Lahontan Reservoir and the outfall waters
below Lahontan Reservoir.
The Division of Health advises:
--No one should eat more than one meal per week of fish caught
from these waters because of possible toxicity from mercury.
A meal is considered to be eight ounces of fish.
--No child or woman of child bearing age should consume any
fish from these waters.
Some larger, older species of fish may have much higher levels
of mercury in their flesh. The Nevada Department of Wildlife and The
Nevada Division of Health can provide specific Information to concerned
individuals on mercury levels by size and fish species.
The study of this problem is continuing and as information may
change, the Health Division will issue new statements."
Attachment 18 lists mercury levels of game fish collected in
1986 from Lahontan Reservoir. Species analyzed include walleye, white
bass, yellow perch, channel catfish, and white catfish. A representa-
15.

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Carson River
Mining Waste NPL Site Summary Report
Reference 13
Excerpts From Health Advisory;
Nevada Department of Human Resources,
Health Division; May 1987

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STATE OF NEVADA	V
DEPARTMENT OF HUMAN RESOURCES
HEALTH DIVISION
The State Division of Health has determined from a study completed
by the State Division of Environmental Protection that a public health
problem exists from eating fish from Lahontan Reservoir. Elevated
mercury levels have been identified in gamefish from the reservoir.
THE DIVISION OF HEALTH ADVISES:
•	No one should eat more than one meal per month of fish
caught from these waters. A meal is considered to be eight
ounces of fish.
•	No child under age 12 should eat fish from Lahontan Reser*
voir.
•	Children 12- to 15-years-old should eat no more than one
four-ounce meal per month of fish caught from these
waters.
•	Pregnant women, nursing mothers and women who may
soon become pregnant should not eat fish from Lahontan
Reservoir.
•	Walleye over 21 inches in length should not be eaten.
The study of this problem is continuing and as information changes,
the Health Division will issue new statements.
Dated: May 1987

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Carson River
Mining Waste NPL Site Summary Report
Reference 14
Record of Communication Concerning
Carson River Mercury Site File; From Heather Stone to
James Cooper and A. Biagti, NDEP; August 14,1986

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CARSCN RIVER MERCURY SITE FILE
RECORD OF aatUNIC-TICN	August 14, 1986
FROM: Heather Stone
TO: Janes Cooper, Alan Biagti, MDn>
Called NDEP regarding the Site Inspection Report prepared by the
State. Needed to clarify certain informafinn.
The Lahantan Reservoir is not currently used as a drinking water source,
tat it is considered a potential source. All drinking water currently
canes from groundwater.
Part 5, Section III, Q jest ion 10 of the SI Report states that ground-
water contamination is not a problsn because oantaminaticms " 1 microgram/
litre". Hus should read " 1 microgram/litre".
Region IX EPA already has three copies of the 1985 fish bioassays
study. Joanne LaBaw should have a copy of this document that is cited
in the SI Report.
Continued work an this site includes search for additional tailings
piles, monitoring of	wells closer to known tailing pile
locations, and testing for mercury vapor over the reservoir and stream.
Vapor testing is to be ocnpleted within the next two months while the
water levels are at their lowest annual level.
The CEP has not taken acticn an this site because the only conceivable
environmentally sound action is quite expensive. DEP thinks the best
way to address mercury in the reservoir is the impound stream water
before-it flows into the reservoir* during the snow melt season. The
water would then be nTlnwnd to sit until the suspended mercury had
settled out. Hiis nenedy would involve a large differsion and
retention system.
CCNCLDSICN:
This Site inspection Report is pending, awaiting receipt of
data collected fran vapor and well monitoring. Heather Stone will
be the contact until Joanne LaBaw returns fran vacation Septentoer 15.

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Mining Waste NPL Site Summary Report
Celtor Chemical Works
Humboldt County, California
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-OO25, Work Assignment Number 20.
A previous draft of this report was reviewed by Greg Baker of EPA
Region IX [(415) 744-2221], the Remedial Project Manager for the
site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
CELTOR CHEMICAL WORKS
HUMBOLDT COUNTY, CALIFORNIA
INTRODUCTION
This Site Summary Report for Celtor Chemical Works is one of a series of reports on mining sites on
the National Priorities List (NPL). The reports have been prepared to support EPA's mining program
activities. In general, these reports summarize types of environmental damages and associated mining
waste management practices at sites on (or proposed for) the NPL as of February 11, 1991 (56
Federal Register 5598). This summary report is based on information obtained ftom EPA files and
reports and on a review of the summary by the EPA Region IX Remedial Project Manager for this
site, Greg Baker.
SITE OVERVIEW
The Celtor Chemical Works Mill site covers 2.5 acres and is located in Humboldt County, California,
in the Klamath mountain range. The site is located at the north end of the Hoopa Indian Reservation
and is several hundred feet from the Trinity River, which is classified as a Wild and Scenic River (see
Figure 1) (Reference 1, page 1). A 1970 census counted approximately 4,000 residents on the Hoopa
Indian Reservation: 1,056 Native Americans and 2,742 non-Native Americans. There are
approximately 900 residences located within 3 miles of the site Local residents use the area for
agriculture, fishing, and grazing their domestic animals (Reference 2, page 2-1). Celtor Chemical
leased the site from the Hoopa Indian Tribe, which owns the reservation lands (see Figure 1)
(Reference 3, page 4).
Sulfide ores intended for extraction processes were transported to the Celtor Mill site from the
Copper Bluff mine. The distance between the Celtor Mill and Copper Bluff Mine is not known
Copper, zinc, and other precious metals were extracted at the Celtor Mill (Reference 3, page 1).
Celtor Chemical Works began operations in 1957. In 1962, the California Department of Fish and
Game issued citations to Celtor Chemical Works due to pollution and fishkills in the nearby Trinity
River. The site was subsequently abandoned in 1962. The Trinity River, which is an important
fishing resource for the Hoopa reservation, was likely to have been contaminated from materials that
had washed out of the heavily traveled river access road (Reference 1, page 1).
Until 1985, local residents obtained their drinking water from a well upgradient of the Celtor Mill.
Downgradient of the well, the aquifer flows directly below the Celtor plant. Although the well at the
1

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Celtor Chemical Works
FIGURE 1. SITE FACILITIES AND IRM REMOVAL AREA

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Mining Waste NPL Site Summary Report
site was found to be free of inorganic contamination (except iron), most residents now draw their
drinking water from a surface-water source. The reason for this change is not known. Some homes,
however, still rely on the aquifer for water Available information did not explain the reason for
changing drinking-water sources (Reference 3, page 4).
The site was proposed for the NPL on December 30, 1982, and finalized in September 1983 A
Record of Decision (ROD) addressing an Initial Remedial Measure (IRM) was signed in October
1983, and work was initiated by EPA in December 1983. The IRM involved the removal of all
visibly contaminated materials from the site to a California Class I hazardous waste landfill This
included all remaining tailings, nonconcrete structures, and a portion of the soil in the pasture
adjacent to the site. In addition, the access road to the fishing area was recovered with new gravel
and the site area was fenced off The cost of the IRM was approximately $337,000 (Reference 3,
page 5; Reference 4, page 1)
Investigation of the site continued and a Final Remedial Investigation/Feasibility Study (approved in
October 1984 and released in April 1985) examined area samples of surface and subsurface soil,
surface and ground water, and air. A second ROD was signed on September 30, 1985, and addresses
full excavation and offsite removal of contaminated materials as the Remedial Action for the site
(Reference 3, Signature Page). These activities commenced in 1987 and were completed in October
1988. As of February 1990, $4.9 million had been expended for site clean-up (Reference 4, page 5)
OPERATING HISTORY
The Celtor Chemical Works Mill began operation in 1958. Sulfide ores were mined at the Copper
Bluff Mine and shipped to the mill. A dissolved air flotation process was used to extract copper,
zinc, and other precious metals from the mined ore and produce concentrates Ore concentrates
resulting were then transported offsite for further refinement. Tailings were then either stockpiled or
presumably flushed down a gully to the Trinity River. The tailings may have been the cause of the
numerous fish kills for which the California Department of Fish and Game cited the company
(Reference 3, page 4).
After the facility ceased operation in the early 1960's, an abandoned tailings pile washed into the
Trinity River during a heavy flood in 1964. The State of California Department of Health Services
also noted that other tailings may have caused acidic surface-water runoff in the area and area soils
with high heavy metals concentrations (Reference 3, page 5).
3

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Celtor Chemical Works
Contaminated material at the site was found in the following areas:
•	Tailings pile - Based on field cross-sections, the tailings pile consisted of 530 cubic yards of
contaminated material.
•	Ore bins - Based on the dimensions of the bins and estimated average depth of the material, the
two ore bins were estimated to hold 260 cubic yards of contaminated material.
•	Vats - The Department of Health Services and Region IX estimated that the three vats held a
total of 75 cubic yards of contaminated material.
•	Access road - It was estimated that 100 cubic yards of contaminated material needed to be
removed from the access road. This is based on scraping 6 inches of material off the road
(beginning near its intersection with the ore haul road and ending near the north end of the
contaminated area of the field).
•	Ditch - It was estimated that 50 cubic yards of material needed to be removed from the ditch
by scraping 6 inches of material off the bottom and sides of the ditch This extended along the
ditch, adjacent to the contaminated portion of the field.
It was estimated that 335 cubic yards of material would need to be removed from contaminated areas
of the field, including those areas where there was no vegetative growth (assuming the removal of 6
inches of material) (Reference 1, page 4). The types and concentrations of contaminants found in
these areas will be discussed in the Site Characterization Section below.
SUE CHARACTERIZATION
The site encompasses the dismantled mill sides site, which is separated from a privately owned
pasture by a fishing access road. There is also a heavily wooded, shallow gully onsite that discharges
to the Trinity River. Areas around the mill site are bare to partially vegetated and consist of native
soil contaminated by ore and tailings (Reference 3, page 1).
Soils
A total of 177 soil samples were taken from the site in five areas: the pasture, the fishing access
road, the tailings piles, the process plant, and the gully. Several samples were contaminated with
cadmium, copper, Lead, and zinc above the California Assessment Method (CAM) for making Total
Threshold Limit Concentration (TTLC) criteria. Table 1 summarizes both the CAM TTLC limits for
4

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Mining Waste NPL Site Summary Report
constituents of concern and sample contamination ranges at each of the sample areas (Reference 2,
Appendix C).
TABLE 1. SOIL SAMPLE CONCENTRATION LEVELS (IN mg/kg) AND ASSOCIATED
CAM TTLC LIMITS AT CELTOR CHEMICAL WORKS, CALIFORNIA.
Area/Limit
As
Cd
Cu
Pb
Hg
Ag
Zn
pH
CAM TTLC
500
100
2,500
1,000
20
500
500
< 2
Pasture
12 -
< -
91 -
6-
0.085 -
2.5 -
190 -
2 89 -

270
50
975
2,650
13
125
11,200
6 82
Fishing
8 -
< -
70-
< -
< -
< -
65 -
2 83 -
access road
165
104
3,990
679
43
30
23,300
7 59
Tailings
7 -
< -
52 -
< -
< -
< -
55 -
2 64 -
pile
270
44
5,600
530
2 8
29
17,200
8 06
Process
3 -
< -
34-
< -
< -
< -
60-
2 71 -
plant
295
69
124,000
1,050
3.4
43
13,900
8 73
Gully
6-
< -
78 -
2.3 -
0.065-
< -
89 -
2 712 -
sediment
600
310
25,500
1,680
4.4
115
62,100
7 18
< - Undetectable level in laboratory analyses
Source: Draft Remedial Investigation Report, Celtor Chemical Works, Hoopa, California;
March 1985
Ground Water
Ground water occurs in the alluvial channel deposits, alluvial floodplain deposits, and colluvial
deposits. Small amounts of water can be transmitted through joints and fractures in the phyllite
bedrock. Rainfall which does not run off the hillslopes and valley floor infiltrates the alluvial and
colluvial deposits and moves through these unconsolidated deposits towards the Trinity River
(Reference 2, page 3-5).
The unweathered phyllite bedrock appears to act as a low permeability barrier to the downward
movement of ground water and forms a relatively low permeability surface over which ground water
moves from the higher elevations to discharge areas along the Trinity River. Springs are visible at
the contact of bedrock and the alluvial terrace deposits at the eroded eastern channel boundary of the
Trinity River near the Celtor site (Reference 2, page 3-5).
5

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Celtor Chemical Works
Analysis of ground-water samples taken during the Remedial Investigation (beneath and in the vicinity
of the site) showed no contaminants, with the exception of iron, which occurs naturally at the site
(Reference 3, page 8).
Surface Water
Surface water sampled upgradient of the site had concentrations of cadmium, copper, lead, and zinc
above Federal Ambient Water Quality Criteria for Freshwater Aquatic Life (AWQCFAL) levels, as
well as levels of iron exceeding Federal Drinking Water Standards (DWS). Surface water sampled in
the immediate vicinity of the site was found to have levels of cadmium, copper, lead, and zinc
exceeding both DWS and AWQCFAL (see Table 2) (Reference 2, pages 5-4 through 5-6).
River water sampled above the site discharge gully had cadmium levels in excess of AWQCFAL and
copper at 48 percent of the limit. Water from the site discharging to the river through the gully
exceeded both DWS and AWQCFAL for cadmium, copper, iron, and zinc and the AWQCFAL for
lead. However, river water sampled immediately downstream of the discharge did not exceed any
AWQCFAL standards (see Table 2 ) (Reference 2, page 5-6).
Air
Although local residents noted the presence of noxious sulfur odors in the area, air samples revealed
no detectable concentrations of sulfur-related pollutants (Reference 3, page 8).
ENVIRONMENTAL DAMAGES AND RISKS
The final Remedial Investigation found that the Celtor Chemical Works site poses a significant threat
to human health and the environment due to elevated levels of arsenic, cadmium, copper, lead, and
zinc in soil and surface-water samples in excess of CAM TTLC, DWS, and AWQCFAL.
Direct contact with contaminated water, especially through ingestion of more than 2 liters per day,
could cause human health problems. Ingestion of contaminated soils is also thought to be a potential
human health hazard. The State of California issued citations to the Celtor Chemical Works due to
fishkill incidents in the Trinity River. Contamination may be responsible for the defoliation of lands
adjacent to the site due to runoff (Reference 3, page 9).
6

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Mining Waste NPL Site Summary Report
TABLE 2. DISSOLVED METAL CONCENTRATIONS (IN Mg/l) AND ASSOCIATED WATER
QUALITY STANDARDS AT CELTOR CHEMICAL WORKS, CALIFORNIA.
Water Type/
Limits
As
Cd
Cu
Fe
Pb
Hg
Ag
Zn
PH
DWS
50
10
1,000
300
50
2
50
5,000
NA
AWQCFAL
440
0 18
56
NA
1.95
0 2
2.47
47
NA
Spring
Water
< -
50
< -
3
< -
52
33 -
350
<
<
< -
4.6
< -
1,560
69 -
8 2
Drainage
<
0.22
16
1,230
4.7
<
<
50
66
River
Water
<
< -
0.18
2.7 -
4
258 -
265
<
< -
03
<
5.5 -
11
7 2
Ground
Water
< -
50
< -
28
< -
66
32 -
1,340
< -
1 9
<
<
< -
54
60 -
6.9
Surface
Water
<
6 1 -
241
232 -
9,690
123 -
16,600
< -
7
< -
0.4
< -
3.1
1,610 -
47,800
36-
66
< - Undetectable level in laboratory analyses
DWS - Drinking Water Standards
AWQCFAL - Ambient Water Quality Criteria for Freshwater Aquatic Life
NA - Not Available
Source: Draft Remedial Investigation Report, Celtor Chemical Works, Hoopa, California;
March 1985
The site is located within a Hoopa Indian reservation that relies on the Trinity River for fishing and a
nearby pasture for grazing cattle and agriculture. As a result of activities at the Celtor Mill, the area
is no longer suitable for agriculture and the nearby Trinity River can only be used for limited
recreational fishing (Reference 2, page 2-2).
The ROD for the IRM at the Celtor site notes that there are not enough data available on the ditch
and field neighboring the site to establish the nature of transport of pollutants from these areas to the
Trinity River or to confirm the imminent threat to the public health or the environment (Reference 1,
page 2).
7

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Celtor Chemical Works
REMEDIAL ACTIONS AND COSTS
There were three areas of the site, containing an estimated total of 1,350 cubic yards of material that
needed to be addressed:
•	The onsite tailings piles, ore bins, and vats contain approximately 865 cubic yards of highly
contaminated material (up to 50 percent heavy metals).
•	The heavily travelled access road adjacent to the site - if scraped to a depth of 6 inches along
the edges of the site - will yield an estimated 100 cubic yards of material.
•	The ditch and field adjacent to the site. These areas have been defoliated due to years of acidic
runoff from the site. Assuming that 6 inches of topsoil is scraped from this area, another 385
cubic yards of materials must be handled (Reference 1, page 2)
Because of the proximity of a housing development and possible impact on the Trinity River, EPA
conducted an Initial Measure Investigation and Focused Feasibility Study in 1983. The study
concluded that the removal of all visible contaminants (not including concrete structures) and some of
the topsoil would be initially sufficient. Approximately 1,400 cubic yards of contaminated materials
were removed from the site. During these activities, more contaminated materials were found in
locations that had not previously appeared contaminated or that were not sampled. The discovery of
additional contamination suggested the need for further remedial activities (Reference 4, page 2).
After a second Remedial Investigation/Feasibility Study in 1984 and subsequent consultation with
other involved agencies, EPA decided on excavation and offsite removal of contaminated materials.
This Remedial Action option was chosen because of its cost effectiveness in protecting human health
and the environment. Removal involves the extraction and burial of all visible contaminants (not
including concrete structures); excavation and disposal of soil contaminated above site-specific action
Levels at a California Class I landfill; and backfill excavation with clean fill meeting action Level
requirements to protect human health, welfare, and the environment (Reference 3, pages 15, 16, and
26). The site was revegetated after remedial construction activities were completed in October 1988.
Post-closure maintenance was also necessary for 1 year to ensure that the vegetation survived. The
Army Corps of Engineers continued to monitor and maintain the site until October 15, 1989
(Reference 3, pages 5 and 6).
8

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Mining Waste NPL Site Summary Report
CURRENT STATUS
As of February 1989, remedial activities at the Celtor site cost $4 9 million. Additional unpaid wages
owed to workers may add approximately $1.5 million to the total remediation cost (Reference 4, page
5). This is a result of the Department of Labor's opinion that Celtor Chemical inappropriately waived
the minimum wage rate requirement for workers involved in physical work during site remediation.
The matter, however, is still unresolved (Reference 4, page 5).
By September 1990, clean-up was complete and the close-out report generated (Reference 5). A
Potentially Responsible Party (PRP) search is ongoing as the statute of limitations runs out in I to 2
years (Reference 5). Some PRPs on the list may be bankrupt, and some owners/operators may have
their assets shielded from liability. No conclusions have been reached (Reference 5).
9

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Celtor Chemical Works
REFERENCES
1.	Superfund Record of Decision, Celtor Chemical Works Site, California; EPA, Office of
Emergency and Remedial Response, EPA ROD R09-83/001; October 1983
2.	Draft Remedial Investigation Report, Celtor Chemical Works Site, Hoopa, California; EPA;
March 1985.
3.	Superfund Record of Decision, Celtor Chemical Works, California, (Second Remedial Action);
EPA, Office of Emergency and Remedial Response, EPA ROD R09-85/009, September 30, 1985.
4.	Superfund Site Close-out Report, Celtor Chemical Works, Hoopa Valley Indian Reservation,
Humboldt County, California; EPA; September 29, 1989.
5.	Telephone Communication Concerning Celtor Chemical Works, From Maria Leet, SAIC, to Greg
Baker, EPA Region IX; October 19, 1990.
10

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Mining Waste NPL Site Summary Report
BIBLIOGRAPHY
EPA. Draft Remedial Investigation Report, Celtor Chemical Works Site, Hoopa, California
March 1985.
EPA. Superfund Site Close-out Report, Celtor Chemical Works, Hoopa Valley Indian Reservation,
Humboldt County, California. September 29, 1989.
EPA, Office of Emergency and Remedial Response. Superfund Record of Decision, Celtor Chemical
Works, California, (Second Remedial Action), EPA ROD R09-85/009. September 30, 1985.
EPA, Office of Emergency and Remedial Response. Superfund Record of Decision, Celtor Chemical
Works Site, California, EPA ROD R09-83/001. October 1983.
Leet, Maria (SAIC). Telephone Communication Concerning Celtor Chemical Works to Greg Baker,
EPA Region IX. October 19, 1990.
11

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Celtor Chemical Works
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From Superfund Record of Decision,
Celtor Chemical Works Site, California;
EPA, Office of Emergency and Remedial Response,
EPA ROD R09-83/001; October 1983

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UnitM Sl»tM	OWa of	- '.Z - i
Environm*nal P»et»etian	£m*rg*nev infl	3.-:se' '383
'{•"O	R«tee-i(«
106?
Superfund
Record of Decision:
Celtor Chemical Works
Site, CA

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; = J SCO 309 JJ JC
crircR c:-:iyvor::s
Reccrc cf recisicn Sriefmg
Purees a cf t::e 17C'.:
trir.szcrt arc ciiccsil cf tilings pil = s i.-c scii ccr.tir:: -.i-i:
vitn heavy metais sucr. as cacTiur., copper and z:c. This
remedial action is necessary to prevent puolic contact vitn
the contaminated material and to protect tne aquatic environment
of the Trinity River.
Background:
*	The Celtor Chemical wor^s site consists of approximately
2.5 acres at the north end of the Hoopa Valley Indian
Reservation in I-Iunselct County, California. The Trinity
River is within several hundred feet of the site.
*	The Celtor site was operated as a sulfide ere processing plant
from 1957 to 1962. The site was abandoned in 1962 following
California Department of Fish and Game citations for
pollution and fishkills in the Trinity River.
*	Contaminated material from the site has washed onto the
heavily traveled access road to the Trinity River and
it is likely that the contamination runs off into the river
during the winter rainy season. The river is an important
fishing resource for tne Koopa reservation.
*	In July 1981 the site was identified in a California state-
wide abandoned industrial waste facility survey. Celtor
was included on the proposed (now final) National Priorities
List in December 1932.
Remedial Planning Activities to Date*
*	In May 1983/ a Focused Feasibility Study (FFS) of the site
was recommended by EPA Region 9 and the California Department
of Health Services (DOHS). This FFS was initiated in June.
*	During the FFS, CH2M-Hill reviewed the existing monitoring
data on the site and evaluated the potential alternatives
to remedy the site. An assessment which weighed the
potential public health impacts of the "no action" alternative

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August 15c 3.
*	There are thres areas of t.*.-= site, containing an estimate!
total c: 1350 c-isic yarcs c: -itenal, -*r. :cn r.eec co ce
accressec by t.~e I5-S:
The cnsite taili-rs piles, ere bir.s anc vats corti:-.
appror.i.-ately ScE :u::: yaros of highly c:r.::r:."i:sc
The heavily ;ra>;elcC trcess ::i:	to site. :;
scraped to a deptn of 5 inches along tne ecges o: tr.e
site, this read will yield an estimated 100 cum: yaros c:
material. The action will address tne road to protect
the health cf individuals using it.
The ditch and field adjacent to tne site. These areas
have been defoliated due to years of runoff from tr.e
site. Assuming that 6 mcnes of soil is scraced frri
these areas, another 33 5 cubic yards of material muse,
be handled.
*	The last category of material is somewhat different from
the onsite material and the adjacent road in tnat there is
not enougn data availaole on tr.e ditch and the field to
establish the transport of pollutants from these areas to
the Trinity river or to confirm a imminent threat to the
public health or the environment. The few data points we
do have suggest that it is reasonable to assume such a
transport, however. The costs of the remedial investigation
to confirm the threat to the environment, together with
tne additional costs to the Superfund to handle the aitch
and field under a separate remedial action construction
contract next year, far exceed the estimated $60,000 to S70,Q00
cost to include the ditch and field in this IR.M. Therefore,
it is judged to be more cost effective to include those
areas in this action.
*	Five alternatives are evaluated in detail in the FFS:
-	Offsite transport and disposal
-	Encapsulation
-	Encapsulation with Neutralization
-	Encapsulation with Solidification
-	Encapsulation with a Concrete Vault
*	The Cost Effectiveness Evaluation of these options is presented
in Table 1. Although the offsite removal option is not the
least expensive option, it is the lowest cost alternative wnich
is technically feasible and reliable and which effectively
mitigates and minimizes damage to and provides adequate protectio
for the public health, welfare and the environment. The
recommended cost-effective remedy to limit exposure or
t.nreat of exposure to a significant health or environmental
hazard is offsite transport and disposal of the tailings
piles and contaminated material.

-------
-4-
Volumes cf centir.iri2.t=c matanals »er= estimate:: for eacr. cf tr.e folic«-
mg areas:
0 IDLINGS PILE
5i.£€2 cr. fl
0 ORE BINS
Eased cn the dimar.sic-is of the bins and estimated average depth cf
material in eacn bin, tr.e two ore Dins are estir.fited to nold 260
c^hic yarcs cf material.
0 VATS
COHS ana Region 9 estimated that tr.e thres vats hold a total cf 75
cubic yarcs of material.
0 ACCESS ROAD
It is estimated that 100 cubic yarcs cf material will need to be removed
fran the access road. This is based on scraping 6 inches off tne roac
beginning near its intersection with the ore haul road and ending near the
north end of tne contaminated area of the field.
° DITCH
Fifty cubic yards will be removed frcm the ditch by scraping 6 incnes of
material off the bottcm and sides. This would extend along the ditch,
adjacent to the contaminated portion of the field.
0 FIELD
Assuming that six inches of material will be removed from the contaminated
area of the field an estimated 335 cuJdic yards of material would be
ranoved. This would include tha area of the field wnere there is no
vegetation growing.
0 TOTAL VOLUME
Based on presently available information, the selected ERM will remove
a total estimated volume of 1,350 cubic yards of contaminated material.
VI. DEVELOPMENT OF POTENTIAL ALTERNATIVES
EXiring the develccment of potential alternatives, mining companies in
California, ttevada, and Arizona were contacted to determine their interest
m the material renaming cn the Celtor site. This research dia not identify
any company interested in the "mine tailings," which have the hignest
concentrations of zinc and copper of the material renaming on the site.

-------
Celtor Chemical Works
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Draft Remedial Investigation Report,
Celtor Chemical Works Site, Hoopa, California; EPA;
March 1985

-------
DRAFT
REMEDIAL INVESTIGATION REPORT
CELTOR CHEMICAL WORKS SITE
HOOPA, CALIFORNIA
WA 121.9L280
W69628.00
March 1965
This document has been prepared for the U.S. Environmental
Protection Agency under Contract No. 68-01-6692. The
material contained herein is not to be disclosed to,
discussed with, or made available to any person or persons
for any reason without the prior expressed approval of a
responsible official of the U.S. Environmental Protection
Agency.

-------
Chapter 2
SITE FEATURES SUMMARY
PHYSIOGRAPHY
The Celtor Chemical Works site is located at the north end
of the Hoopa Valley which is in the Klamath Mountains of
northwestern California. The site is at the base of a steep
slope leading up to State Highway 96 approximately 20 0 feet
vertically and 200 feet to the east. Agricultural land
along the Trinity River is adjacent to the site on the west
side.
DEMOGRAPHY
The Celtor Chemical Works site is located on the Hoopa Valley
Indian Reservation. The area around the site is generally
rural. It was estimated in the EPA records for the hazardous
ranking system prepared in 1982 that 900 residences were
within a 3-mile radius of the site. A 1970 census reported
.3,798 persons living on the reservation: 1,056 Indians and
2,742 non-Indians. In 1972, there were 1,344 tribal members
and an unknown number of non-Indians.
LAND USE
Property on which the site is located is owned by the Hoopa
Indian Tribe. The processing plant area and former tailings
pile area are fenced off and posted with warning signs to
restrict public access. The fishing access road through the
site and the gully north of the site are open without restric
tions, and the road is used by the public for access to the
Trinity River. The open field west of the plantsite is
private property used for cattle pasture.
2-1

-------
NATURAL RESOURCES
There are no known mineral resources located within the site.
Ore formerly processed at the plant was hauled in from a
mine located about one-half mile to the north. In its pre-
sent condition, the site is unsuitable for agriculture, and
the northern end of the site is useful for limited recrea-
tional purposes (fishing). The site is adjacent to the
Trinity River, which is part of the National Wild and Scenic
River System. This section of the Trinity River is classified
as "scenic."
ECOLOGY
The site is located at the base of a steep wooded hillside
and is adjacent to a valley floor which is pastureland. The
valley was originally thought to be covered with live oak,
white oak, tan oak, manzanita, madrone, fir, pine, and redbud
trees. Most of the valley has been cleared. The dominant
vegetation remaining on the valley floor is annual grasses,
clover, plantian, chicory, yellow star thistle, other forbs,
wild grape, wild blackberry, wild rose, western redbud, and
digger pine.
CLIMATE AND HYDROLOGY
The climate is characterized by warm, dry summers and mild,
wet winters. Mean annual precipitation is 57 inches, which
is mostly rain. Average snowfall is 0.4 inch. During the
3-month summer period, precipitation averages 1.32 inches.
The mean annual temperature is 56.9*F, mean winter tempera-
ture is 45.1°P, and mean summer temperature is 70.9®F.
Surface runoff flows across the site generally in a westerly
direction until intercepted by ditches which carry it in a
northerly direction and eventually to the Trinity River.
2-2

-------
SITE HYDROGEOLOGY
Groundwater occurs in the alluvial channel deposits, alluvial
flood plain deposits, and colluvial deposits. Small amounts
of water can be transmitted through joints and fractures in
the phyllite bedrock. Rainfall which does not run off the
hillslopes and valley floor infiltrates into the alluvial
and colluvial deposits and moves through these unconsolidated
deposits towards the Trinity River.
The unweathered phyllite bedrock appears to act as a low
permeability barrier to the downward movement of groundwater
and forms a relatively low permeability surface over which
groundwater moves from the higher elevations to discharge
areas along the Trinity River. Springs are visible at the
contact of bedrock and the alluvial terrace deposits at the
eroded eastern channel boundary of the Trinity River near
the Celtor site.
Phyllite bedrock occurs at a depth of 24 to 25 feet at Bore-
hole G-l. The top 2 or 3 feet of bedrock was severely wea-
thered, soft, and gray-green in color. This weathered zone
appears more permeable than the unweathered bedrock. Bedrock
was not encountered at a depth of 49 feet in Borehole G-2.
In Borehole G-3, the phyllite was encountered at a depth of
62 feet. At this location it was moderately fresh, hard,
and green. A geologic cross section through Boreholes G-l,
G-2, and G-3 is shown in Figure 5.
The alluvial deposits consist of a permeable 2- to 4-foot-
thick sandy gravel stratum overlaid by less permeable sandy
silt of up to 60 feet in thickness. The sandy silt appears
to act as a partially confining layer above the sandy gravel.
The sandy gravel appears to act as the primary zone of
3-5

-------
tailings east of it (B-16 to B-24 area) and picked up some
contamination. However, based on the present information,
it is not certain if W-13 test values are at background
levels, or represent contamination, since no upgradient sam-
ples are available for this area.
GROUNDWATER
Samples from Wells G-l and G-3 represent water primarily
derived from the thin gravel aquifer that overlies the
bedrock. Water from Well G-2 is derived from the silt layer,
and based on the conditions of the monitoring well installa-
tion (stopped short of the gravel and produced little
water), it does not appear that appreciable water from the
underlying gravel aquifer is entering the monitoring well.
Analyses of water from Well G-2 indicate that the DWS for
iron is exceeded, but all other test values are well below
the DWS. The CFAL limits are met or exceeded by cadmium,
copper, lead, and zinc values (it may not be appropriate to
apply the latter criteria to groundwater). We cannot be
certain whether or not the test values shown by the G-2
sample represent an elevation above background for water in
the silt layer (i.e., contamination). Note the proximity of
concentrated sulfide tailings at Boring H-20; it is credible
that water infiltrating through the tailings deposits became
contaminated and moved down to the groundwater table
(located at 42 feet), or that previously contaminated site
runoff may have infiltrated to the groundwater table. These
test values may represent the degree of contamination (not
just background) present in saturated portions of the silt
layer.
The test results from Wells G-l and G-3 suggest that water
from the gravel aquifer is not contaminated. The value for
5-3

-------
iron in G-l is near the DWS limit, but is much lower than
the iron values shown by the contaminated surface water and
is near the Trinity River values we tested. The estimated
arsenic value of 50 vg/L is a questionable value; however,
even this does not exceed the DWS or CFAL limits.
SURFACE WATER—UPGRADIENT FROM THE SITE
Sample No. 197 (Location W-l) was taken in the drainage
ditch that passes through the west side of the site, but at
a location presumed to be upgradient and uncontaminated by
the site. This sample had an iron content that exceeded the
DWS# and cadmium, copper, lead, and zinc values that
exceeded the CFAL limits. Based on flow estimates made in
the field, SO to 75 percent of the water flowing in the
gully below (north of} the site comes from upgradient via
this ditch. Therefore, a significant proportion of the
surface discharge of the gully to the Trinity River is
already in excess of CFAL limits before it passes through
the site.
SURFACE WATER—IMMEDIATE VICINITY OF THE SITE
UPPER NORTHEAST PORTION OF SITE
Runoff originating in the northeast corner of the site was
sampled at Location W-9. This water was in contact with
tailings or waste rock similar to those sampled in Bor-
ing B-24 (see Noa. 1300Y-1 and -2). DWS limits for cadmium
and zinc were exceeded, and the limit for copper was nearly
exceeded. CFAL limits for cadmium, copper, and zinc were
exceeded.
TAILINGS PILE AREA
5-4

-------
Sample W-2 was from the ditch at the lower (west) side of
the former tailings pile area and represents runoff that has
been in contact with contaminated soil (see Samples 99, 118,
and 128 from Borings B-2, B-4, and B-5, respectively). Sam-
ple W-2 test values for cadmium, copper, iron, and zinc
exceed both DWS and CFAL limits, and the CFAL limit for lead
was also exceeded.
DITCH LEAVING THE PLANTSITE
Sample W-6 was taken farther down the same ditch from the
W-2 sample location. This location contained water from
both the tailings pile area (W-2) and the plantsite or area
of the structures. This location is immediately above where
onsite runoff merges with drainage water from south (upgra-
dient) of the site. DWS and CFAL limits for cadmium,
copper, iron, and zinc are exceeded, and CFAL limits for
lead and mercury are exceeded. This sample presents the
highest degree.of contamination of all water samples tested
for the Rl.
DRAINAGE DITCH—WEST OF THE FISHING ACCESS ROAD
Sample W-7 was taken on the upstream side of the culvert
that passes beneath the fishing access road. Water at this
point is a mixture of upgradient and site runoff. The DWS
limit for iron is exceeded, and CFAL limits for cadmium,
copper, lead, and zinc are exceeded. Tested values for
cadmium, copper, and zinc show large increases (15 to
30 times) compared to Sample w-1 values.
DRAINAGE DITCH BELOW THE SITE
After passing through the culvert, water from Location w-7
merges with water from Location W-6, producing the water
5-5

-------
sampled at Location w-8. dws limits for cadmium, copper,
iron, and zinc were exceeded by Sample w-8. CFAL limits
were exceeded for the same metals plus lead. The contrast
between W-7 and W-8 test values is great and demonstrates
the effects of contamination passing through Location W-6.
TRINITY RIVER AND DISCHARGE FROM THE GULLY
Sample W-10 represents river water upstream from the gully
discharge (site drainage) point. Sample W-ll represents the
gully (site) discharge, and Sample W-12 represents river
water from the very edge of the river, immediately down-
stream from the discharge point. At the time of sampling,
there was approximately 5,000 cfs in the river and less than
one cfs in the stream from the gully (site discharge)
(visual estimate).
Sample W-10 showed a cadmium value in excess of the CFAL
limit and copper at 48 percent of the limit. Iron was at
88 percent of the limit. Water discharged from the site
(W-ll) exceeded both DWS and CFAL limits for cadmium, copper,
iron, and zinc, and the CFAL limit for lead. River water
immediately downstream from the discharge point (W-12) did
not exceed CFAL limits for any metals tested except mercury.
However, this may be an anomaly in the laboratory data since
no mercury was detected in the upstream river or site dis-
charge samples (W-10 and W-ll).
RDR29/046

-------
Appendix C
MASTER SAMPLE DATA LIST
and
SAMPLE DATA LISTS
SORTED BY AREA

-------
TABLE C-J
DMA FOR MEA 1
CELTOS OBIICAL HOWS— SOIL SAIPLE DATA
REItOIAL IMJE5IIGAI10N REPORT
CH2H HILL JOB NO U41428 00 DO
smu una
LOCATION
DEPTH (FT )
DATE
TAG No
Ai
Cd
SAS-1300Y- 14
SF-28
0-0 1
11-28-54
1-1144
21
4 2
SAS-1J00I- 17
SF-24
0-0 1
11-28-84
1-1147
17
5 4
SAS-130DI- 16
SF-30
0-0.1
11-28-84
1-1148
120
10
SAS-13001- 11
SF-25
0-0.1
11-20-84
1-1141
14
5
SAS-I30QT- 20
SF-27
0-0.1
11-28-84
1-1170
24
U
SAS-130DT- 21
SF-21
0-0 1
11-28-84
1-1171
22
1
SAS-1300T- 22
ff-31
0-0 1
11-28-84
1-1172
IB
4.1
SA5-13O0V- 23
SF-32
0-0 1
11-28-84
1-1173
40
13
SAS-I300T- 26
SF-32 (OIF)
0-0.1
11-28-84
1-1174
85
12
SAS-1JD01- 144
H-8. SF-1
0-0.1
12-03-84
1-1214
30
3 4
SAS-13O0T- 146
H-fli S-l
l-l 25
12-03-84
1-1214
270
50
SAS-1103t- 147
H-8, S-2
3-3 5
12-03-B4
1-12T7
33
4.2
SAS-ISJQT- 148
H-8. S-3
4 5-5
12-03-84
1-1218
10
4.1
SAS-1300T- 14S
H-1> SF-1
0-0 1
12-03-84
1-1215
40
11
SAS-iiaar- ut
H-1. S-l
1-1 25
12-03-84
1-1211
14
<
SAS-I300T- ISO
H-1. S-2
3-3.5
12-03-84
9-1303
12
3 4
SAS1300Y- 151
H-1. S-3
4.5-5
12-03-84
1-1304
12
<
AH LIMITS FOB TTU ICTM.S



SOD
100
SAS-130DT- IS
SF-86
0-0 1
11-28-84
9-114S
11
<
iabiE r
«TALS CONCENTRATIONS (ig/kj)
Cu
ft
Pb
H)
As
2n
CN f»
348
48200
ei
0 41
5.7
503
< 4 24
313
32500
45
D 3
[4 4]
711
< 74 14'
414
42BOO
.378
1 7
22
1470
< 2 81
11
40400
4
0 12
[4 2]
117
( 4 82
SOI
41000
123
a 54
8 4
2009
< 4 24
275
44000
54
0 14
5
575
( 4 21
203
42500
40
0 18
4 2
413
< 4 32
828
53000
183
I 4
14
2050
< 3.21
175
48700
334
1 4
20
1740
< 3 1
500
41400
143
0.77
8 2
HI
< 3 72
577
30200
2450
13
125
1I7C0
< 3 4 Pi
330
«w»im
21
(0 015)
[3.7]
211
< 3.7
231
44300
1
[0 085]
5 5
217
( 3 14
403
42000
138
0 78
8 1
1420
< 2 1
318
38700
8
0 1
4 4
238
< 3 75
182
34600
14
0.13
[2.51
in
< 3 SI
170
3B700
8
[0.085]
(3 8)
113
( 3 82
2500
15
31100
1000 20 500 5QD0	<2
I 0.12 [3 7] 323 <411

-------
TABLE C
OAIA FOR AREA 2
CELTOR CKHICAL WKS SOIL SAtnE DATA
RE1CDIAL INVESTIGATION REPORT
CH2I) HILL JOB NO U&9&78 00 BD
SAWLE MISER
LOCATION
DEPTH (Fl
OATE
TAB No.
Ai
SAS-1300T-
24
SF-33
0-0 1
11-28-64
9-1174
25
SAS-1300T-
n
B-7. SF-1
0-0 1
11-29-84
9-1183
110
SAS-1300T-
34
B-7. SS-l
1-2.5
11-29-84
1-1184
II
SAS-I300T-
35
8-7. 95-2
3-4 5
U-29-64
9-1165
10
SAS-I300T-
34
6-7, SS-3
4-7 5
11-29-64
9-1164
14
SAS-1300Y-
37
8-7. 95-4
MO 5
11-29-84
9-1187
14
SAS-13001-
41
8-3. SF-1
O-O 1
11-29-84
9-1191
145
SAS-13D0I-
42
6-3. SS-l
1-2 5
11-29-64
9-1192
10
SftS-lMOT-
43
8-3. SS-2
3-4 5
11-29-64
9-1193
8
SAS-I300Y-
44
0-3. SS-3
4-7 S
11-29-64
9-1194
9
SAS-I300T-
45
B-3. SS-4
9-10.5
11-29-84
9-1195
15
5AS-1300T-
134
8-1. SF-1
0-0.1
11-30-84
9-1284
IB
SAS-I300T-
141
8-1. SS-5101
0-0.1
11-30-64
9-1291
14
SAS-I300T-
137
B-l. SS-l
1-2.5
11-30-64
9-1287
14
SAS-13001-
138
B-l. SS-2
3-4 5
11-30-84
9-1288
9 5
SAS-13S0T-
13?
8-1. SS-3
4-? 5
11-30-34
9-1289
18
SAS-1300T-
140
B-l. SS-4
8 5-10
11-30-64
9-1290
14
AN LIH1I5 FOB IILC IETALS



500
SAS-1300Y-
15
SF-6S
0-0 1
11-28-64
9-1145
11
fETALS CONCENTRATION
Cd
Cu
Ft
Pb
h9
5
325
40200
55
0 36
25
1810
54000
267
2 2
5
jo
35700
8 5
0.14
<
?7
36700
28
[0 085]
(
J3
42500
11
0.14
(
74
39200
29
0.17
104
39W
73300
479
3 2
17
155
24400
U
4 3
12
133
24200
5
0 26
4.2
107
27000
24
0 If
<
75
40100
12
0 19

230
28500
47
0 58

213
29700
14
0 34

75
32000
<
{

80
23000
<
(

70
34500
9 5
(
36
88
43400
21
(0.085)
100
2500

1000
20
<
95
31100
4
0 12
(pH unitil
Af	In	CH	pH
[5 0]	027	<	5 49
14	4700	<	2 B3
[4 61	2530	<•	5 21
(3 4]	212	<	6 91
5 2	89	<	7 22
[4 21	99	<	7 32
30	23300	<	3 48 Cd. (ui iitd la mod CAD
<	4770	<	5.35
E3 51	*420	<	4 54
C4 01	2410	(	4 n
C3 91	94	<	6 38
(	405 - <	4 75
13 51	524	<	4 25
<	SO	(	5 12
<	45	(	5 35
(	85	<	5 52
[4 21	103	<	7 5?
500 5QQO	(2
[3 71 323 <4 91

-------
TABLE C-3
DATA FOR AREA 3
CEirOR DEfllCAL UOSKS SOIL SAMPLE OATA
REMEDIAL INSTIGATION REPORT
CK2N HILL JOB W ¥49428.BO 00
SAffLE tUKR LOCATION DEPTH (FT ) DATE TAG No
Cd
81
62
85
83
B4
8?
TO
91
n
is
73
99
SAS-1300T-
SAs-i3iior-
SAS-uoor-
SAS-1330T-
SAS-1300T-
SAS-130DT-
SAS-I3O0Y-
sas-i30ot-
SAS-I300T-
SAS-13B0T-
SAS-13DOT-
SAS-1300T-
SAS-I300T-
SAS-1300T- 100
SAS-I300T- 101
SAS-130BT- IdZ
sas-hoot-104
SAS-13001-	103
SAS-13001-	IOS
SAS-1300T-	109
SAS-13QDT-	110
5AS-13DDT-	HI
SAS-13aOT-	112
SAS-1300T-	1I&
SAS-13001-	113
SAS-1300*-	111
SAS-1300T-	115
SAS-l3II0r-	117
SAS-1300T-	I IB
sas-i3am-1 w
SAS-1300T-	123
SAS-130DT-	121
SAS-I300T-	122
SAS-13001-	123
SAS-I300T-	124
SAS-I300r-	125
SAS-130DT-	127
SAS-130DT-	124
SAS-1300T-	126
SAS-13001-	129
SAS-1300T-	130
SAS-13D0T-	131
SAS-I300J-	132
B-10. SF-1
B-10. S5-1
B-10. SS-2
B-10. SS-810)
0-10. SS-3
B-10. SS-4
B-lli SF-1
B-ll. SS-1
B-ll. SS-2
e-ii. ss-3
B-ll. SS-810)
B-ll. SS-4
B-S. SF-1
B-S. SS-1
B-S. SS-2
B-S. SS-3
B-S. SS-810)
8-5. SS-4
B-4. SF-1
B-4. SS-1
B-4. SS-2
8-4. SS-3
B-4. SS-l
B-4. S5-6I0)
SS-5
SS-4
SS-7
55-9(01
SF-1
B-4, SF-2<0)
B-4, SS-1
B-4. SS-2
a-t. ss-3
B-4i SS-4
8-4. SS-S
8-4i S5-4
B-4. SS-810)
8-4, SS-7
B-2. SF-1
8-2. SS-1
B-2, SS-2
B-2, SS-3
B-2, SS-4
B-4.
B-4,
B-4.
B-4.
B-4.
0-O	I
1-2	5
3-4. S
3-4.5
4-7	5
10-ll.S
0-0	1
1-2	5
3-4	5
4-7	S
4-7 S
MO 5
0-0	1
1-2	5
3-4	S
4-7	5
4-7 5
*-10 5
0-0	I
1-2	5
3-4	5
4-7	5
9-10 5
9-10 5
12-13	5
15-14 5
18.5-20
18 5-20
0-0 1
0-0	I
1-2	5
3-4	5
4-7	5
9-10.5
13-14	S
15-14 5
15-14 5
18 5-20
0-0	1
1-2	S
3-4	5
4-7	5
9-10 5
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-B4
11-30-84
11-30-84
11-30-84
11-30-64
11-30-84
11-30-84
11-30-64
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-84
11-30-64
11-30-84
11-30-84
11-30-64
11-30-64
11-30-64
11-30-84
11-30-84
11-30-84
11-30-84
11-30-64
11-30-84
11-30-84
11-30-84
9-1230
9-1231
9-1232
9-1235
9-1233
9-1234
9-1239
9-1240
9-1241
9-1242
9-1245
9-1243
9-1249
9-14SO
9-12S1
9-1252
9-1254
9-1253
9-1258
9-1259
9-1240
9-1241
9-1242
9-1244
9-1243
9-1244
9-1245
9-1247
9-1248
9-1249
9-1270
9-1271
9-1272
9-1273
9-1274
9-1275
9-1277
9-1274
9-1278
9-1279
9-1260
9-1201
9-1202
142
18
28
22
26
24
95
21
IB
28
30
29
270
8 5
8	5
13
15
19
140
34
34
10
21
18
10
14
20
16
44
39
8
14
14
14
20
14
18
7
90
14
12
9	5
9 5
IS
<
4 1
4 2
<
4	8
8 I
<
<
5	4
<
4.4
<
2 8
2 8
(
7 1
44
44
7 5
<
4 5
4.B
<
<
<
<
CAM LIMIS FOt TTLC METALS
SAS-I300T- IS SF-BG
0-0 I 11-28-64 9-1145
500
11
100
<
ffTALS CONCEHTSATIDE l.g/tg)
Cu
Ft
Pb
Hg
A)
Zn
2500
74300
530
1 8
29
2870
52
31500
22
CO 083
(
B5
45
39000
9 5
0 1
C4 7)
93
430
37400
22
0 11
(3 7J
1370
120
40900
25
(0 08)
C3S)
94
43
37100
21
[0 04]
[3 2]
72
1580
57400
342
1 4
19
1100
425
37900
4
0 12
(4 5)
1350
15B
19100
25
0 12
13 9)
405
138
42200
23
10.OB)
<
2B2
149
47100
11
0.11
[4 0)
292
157
40000
24
0 IB
C3-71
412
337
52400
105
0.1
8 5
1000
110
25930
<
[0 OBI
C3 51
114
174
29800
4 8
(0 08)
<
244
44
3D700
4 5
[0 04)
C2 4)
373
65
32500
8
(0 04)
2 5
420
109
37300
23
CO 06)
C4 4)
849
3500
70000
92
2 6
18
12000
5400
74500
no
3 3
28
17200
440
29500
3
0 11
<
2230
65
24000
<
<
<
540
70
34500
11
CO 09]
(
2040
120
34000
11
0 11
<
2140
30
35000
9
<
<
120
45
31500
(
(
<
355
85
35000
10
(
{
100
SS
37500
11
<
<
105
480
39500
44
0 22
<
1520
480
39500
42
0 3
(
1520
105
19500
4 2
[0 08)
(
420
120
33000
a
<
<
2070
95
34000
9
(
<
2710
95
40500
9
<
<
2440
90
41000
10
(
<
38S0
340
370BD
9 5
<
<
1990
155
43500
10
<
(
3770
50
22000
<
<
<
290
1710
57500
70
3
13
3810
70
28000
7 5
0 1
<
215
80
23000
3 4
<
(
S5
40
23500
<
<
{
55
eo
21500
<
0 14
{
40
2500

1000
20
500
5000
95
31100
4
0 12
13 7)
323
IpH units)
CN	pH
<	2 44 Cu ficeeds CAJ1
(	4 07
(	4 45
<	4 04
<	7 2
(	7 31
(	2 83
<	3 13
(	3 3
<	3 4
(	3 3
(	4.31
(	3
<	3 44
(	4 12
(	4 83
(	7 44
<	4 74
<	2 45 Cu and Zf» tttifd CAH
0 7	3 Cu ind Zn ticitd CAH
<	3 71
<	3 7
<	4 44
<	4.99
<	4 71
<	4 8
<	8 04
<	7 87
<	3 12
<	3 09
<	3 05
<	4 13
<	4 02
(	3 3
<	4 92
<	4 43
<	4 94
<	7 05
(	2 44
<	5 73
<	5 71
<	5 53
<	5 88
(2
( 4 91

-------
CEL10R UCniCM. UWflS SOU StfflE OA1A
KftOIAL IWESTIUIIONREPORI
CHZn HILL J06 NO U49428 OH CD
SMFU KlttR L0CAI10N OtPIH (F1 )
SAS-I300T-
SAS-130SV
SAS-13011T-
SAS-13001-
SAS-I300T-
SAS-130DT-
SAS-13QDT-
SAS-13D0T-
5AS-130ET-
SAS-I3O0T-
SAS-I300T-
SA5-13Q0T-
SAS-13Q0T-
SAS-130DT-
SAS-I300T-
SAS-1300T-
SAS-1300T-
SAS-I300I-
5AS-1300T-
SAS-1M0T-
SAS-I3QDT-
SAS-I300T-
SAS-13MI-
SAS-1J0DT-
SAS-I300Y-
SAS-1300T-
SAS-13Q0T-
s*s-i30or-
SAS-1300T-
SAS-1300!-
SAS-I30DI-
SAS-J 3DDT-
SAS-1300T-
SAS-iarar-
SAS-1300I-
SAS-13DDT-
SA5-1300T-
SAS-13001-
SAS-I300T-
SA5-l3tHn-
SAS-1300T-
5AS-130QT-
SA5-1300T-
5AS-I300I-
SAS-1300*-
SAS-130DT-
SAS-I300T-
SAS-13O0T-
6-24.	SF-I
B-21.	SS-1
B-21.	SS-2
B-21i	SS-3
B-2t.	SS-1
B-lt.	SF-1
B-14.	SS-I
0-14.
e-i6>
B-16.
fl-12.
B-1Z.
8-17.
B-12.
8-12.
H-23
SS-2
SS-3
SS-*
SF-1
SF-2101
SS-1
SS-2
SS-3
SF-1
tt-23. S-l
H-23. S-2
H-23. S-3
8-18. SF-1
a-iSi
B-18.
8-181
B-I81
8-101
B-22,
8-221
8-22-
B-22.
B-22,
B-221
B-221
B-17,
B-l J.
B-17.
B-17,
0-17
0-13,
813
B-13,
B-13.
B-13,
B-13
B-13
0-U,
B-ll
BH
SS-1
SS-2
SS-3
SS-S(O)
SS-4
SF-1
SF-2101
SS-1
SS-S
SS-2
SS-3
SS-i
SF-1
SS-l
SS-2
SS-3
SS-1
SF-1
SF-2101
SS-1
SS-2
SS-5
Ms
As
2n
CN
pH
2090
77100
444
3 1
31
1480
(
8 73
11100
84400
830
2 2
31
13900
<
3 51 Cu ind 2n ncnd CAH
74
37100
2
0 12
<
44
<
7 01
93
44100
4
CO 081
<
104
<
7 26
31
33100
4
<
(3 1]
58
<
B 41
121000
180000
207
2 7
(98)
1750
(
2 83 Cu ticttdi CAM
152
31800
(2 0)
<
12 7)
968
<
4 07
24
23700
<
<
[3 1]
114
<
551
49
37700
(
(
[1 3)
147
<
5 94
117
37400
5
<
(1 8)
172
<
7 01
2100
esioo
970
3
38
1410
<
2 71
3870
937H0
992
2.3
43
1980 '
<
2 71 Cu Mctrdt CAN
394
11500
6
0 14
(4 0]
104
<
4 22
514
50500
8
<
5 2
559
<
4 39
191
13700
(1 0}
CO 081
13 9)
151
<
4 29
285
10900
20
[0 091
5 2
2920
(
6 34
571
34900
44
0 12
5 2
2320
<
4 74
82
23800
4 5
<
(3 11
149
<
7 U
82
22900
s
CO 081
CI 1)
122
<
9 19
2850
tmitn
747
2 9
35
3180
2
3
218
42900
n
a 14
[3 8]
179
<
4
512
34700
25
g i
[3 1]
213
<
4 14
129
19400
(1.01
0.11
(2 4)
130
(
4 31
147
25900
<
CO 0951
(3 1)
180
{
4 43
92
13400
<
(0 095)
<
40
<
4 58
3410
71400
1040
2 8
10
3770
3 4
3 02 Cu and Pb ticttd CAM
2740
45800
934
2 7
28
3320
i a
3 2 Cu ticctdi CAR
238
42500
43
0 34
(1 41
261
<
3 94
318
42500
848
1 9
21
529
<
3 45
135
39200
34
0 11
[3 7]
174
<
3 94
347
288110
4
0 14
[1 2]
553
<
4.84
1540
28200
24
0.12
(
818
<
5.01
1510
40400
573
2 1
25
1130
<
2 88
101
10900
23
CO 095]
(3 4)
109
<
7
101
11100
4 5
<
(3 81
214
(
7 05
49
34000
22
<
(1 51
81
<
7 07
78
1I3IT0
24
0 1
[3 4]
99
<
4 84
1550
59900
378
2
19
2720
<
3 03
2150
70100
392
2
22
1840
(
3 04
270
10500
10
(0 07]
tl 3)
641
<
4 53
81
39400
28
[0 09]
13 5)
89
<
4 26
80
37900
24
0 11
<
138
<
4 24
B3
38100
9 5
[o oai
<
as
<
4 53
72
16300
5
<
<
203
<
4 64
1710
53800
134
1 7
20
3110
<
3 11
45
21100
3 1
0 1
(3 0)
68
{
6 09
59
29500
7 5
[0 03]
<
81
<
6 1
58
29000
9
(0 06]
(2 5]
10B
(
6 11

-------
5AS-1300I- 78
e-u. ss-5
4-7 5
11-29-84
9-1226
11
<
SAS-UOOt- 79
B-14. SS-*
e S-tO
11-29-64
9-1229
20
<
5AS-1300T- 144
H-15. SM
0-0 1
12-07-94
9-1317
110
11
5A5-1300T- 145
H-15. S-l
1
12-07-84
9-1316
7
5 B
SAS-UOOT- 144
H-15. S-2
3
12-01-84
1-1311
10
4 4
SAS-1300T- 147
H-15. 5-3
4 5
12-07-84
9-1320
10
2 4
SA5-I300Y- 158
TRENCH. S-l
5-5 S
12-03-B4
1-1311
41
30
SAS-lMOf- 159
IBEHCH,5-2(01
5-5 5
12-03-64
1-1112
10
3 1
AH LimiS FOR IRC IETALS



500
100
SAS-1300T- 1
Sf-06
0-D 1
11-26-64
1-1145
11
(
47
27000
33
<
[2 7]
BO
< 4 39
71
312DD
e
13 07)
<
74
< 4 43
3440
4300Q
445
2 7
24
995
< 3 4 Cu ficndi CM
271
35900
i
0 12
[3 0]
142
< 4 38
94
34500
(2 0]
0 13
14 3)
90
( 4 IS
130
35800
7 5
0 14
14 5]
212
( 4 1
1030
37100
115
0 79
8 4
4240
( 4 1 2n «>c«tdi CAN
124
27700
25
0 12
(
358
< 4 83
2500

1000
20
500
5000
(2
95
31100
4
0 12
[3 7)
323
< 4 11

-------
CELTOH ChCtllCAL IWKS SOIL SANPli DA1A
REnEDlAL INVESTIGATION KPOBT
CKZn Hill JOB HO um78 01 00
SAIPIE IU1BER LOCATION
SAS-1300T-	25	SF-34
SAS-I300T-	31	SF-34 (0)
SA5-130D1-	142	ST-34
SAS-130S1-	H3	SF-35
SAS-I300I-	152	H-19. SF-l
SAS-130DI-	153	H-19. 5-1
SAS-1300T-	154	H-19. S-2
SAS-I300T-	160	H-19. S3
SAS-1300T-	161	H-19. 5-4
SAS-I30D1-	162	H-l?, 5-5
SAS-13031-	143	H-19. S-4
SAS-I30QT-	155	H-20. SF-l
SAS-1300T-	154	H-20.SF-2(0)
5AS-13D0T-	157	tt-20, S-l
SA5-1M0T-	177	H-20. S-5I0I
SAS-13DOT-	17*	H-20- S-2
SAS-iJOOT-	IB	H-20i S-3
SA5-1300T-	174	H-20. S-4
SAS-I300r-	171	M-21. SF-l
SAS-1300T-	148	H-21. 5-1
SAS-1300T-	14?	H-21. S-2
SAS-13HDT-	170	H-21. 5-3
SAS-I300T-	172	H-21. S-4
SAS-I300r-	173	H-21. S-5
DEPTH (FT 1 OAte	TAB No
O-O I	11-26-64	9-1175
0-0 I	11-28-64	9-1 ISO
0-0 1	12-02-64	9-1292
D-C 1	12-02-84	9-1293
0-0 (	12-03-94	9-1305
1-2	12-03-64	9-1304
2 25-3 5	12-03-84	9-1307
3	12-07-64	9-1313
4-4 5	12-07-84	9-1314
4	l2-07-«	9-1315
8	12-07-8*	9-1314
0-0 1	12-03-8*	9-1308
0-0.1	12-03-8*	9-1309
2-2.25	12-03-64	9-1310
2	12-08-6*	9-1330
4	12-08-8*	9-1327
4	12-08-8*	9-1328
8	12-08-8*	9-1329
0-0 I	12-08-84	9-1324
1.5	12-08-B4	9-1321
3	12-88-8*	9-1322
*.5	12-08-8*	9-1323
4	12-08-84	9-1325
8	12-08-8*	9-1324
CAil LIMIS FOR ITLC ICIN.S
SA5-130OT- 15 SF-66	0-0.1 1J-28-84 9-1145
(pH uniti)
4	49 In «xc«cdt CAM
3 S3 Cg and Zn eicctd (AH
5.39
5	B4
3	28
4	25
4	05
5	79
7 18
4 49
4.73
2 72 Cu. Pb> and In ticni CAD
2 73 Cu. Pb> and In octtd CAH
2	74 At. (di Cm Pb. and In ucied CM
4	01 At. Cd. Cu. Pbi and Zn «ic«rd CAM
< 01
3	59
3	91
5	07
4	58
3	28
4	09
4 41
4 74
<2
4 91

-------
TABLE C-4
OATA FOR UATER SAHRES--10TAL ItTALS
TOTAL KTALS
lltllttlllll
CELTOf CfCniCAL WORKS UATER SAW.E OATA
REKD1AL INVESTIGATION REPORT
CH2J1 HILL JOB NO U494Z8 00 00
HETALS VALUES IN u^/l	SPECIFIC
SAMPLE			COWUCTANCE
SAtfLEMMffR TYPE L0CAI10N DUPLICATES DATE TAG (WEBS	A. Cd Cu F. Pb H9 A, l« CN	,H U.kcWc.l
SAS-1300T- 1B0
BLAW
B-S

12-13-84
9-1350
d 1352
NO
10
3 2
3 7
H3
to
w
5 2
NS
7 D
	
SAS-IJ001- 200
BLANK
U-21

02-09-85
9-1112
D 1111
NO
10
8 1
18
10
0 3
K)
19
to
7 0
	
SAS-1300Y- 201
BLAIR
U-22

02-09-65
9-1115
0 1117
M)
NO
4 b
41
W
W
W
3 1
Ml
7 0
	
SAS-130OT- IS1
SPRIMi UATER
IMS

12-13-81
9-1353
a 1355
H)
10
3 8
34
10
10
10
Kl
tO
8 2
175
SAS-I300T- 101
SPRING UATER
U-lt>

12-13-81
9-1354
a 1356
K>
M)
3
223
10
w
W
M)
W
7 9
225
SAS-13D0T- 183
SPRING UATER
U-17

12-13-81
9-1359
0 1341
NO
[0.12]
3 4
137
Ml
10
W
8 3
W
7 9
300
5AS-130DY- 191
SPRING UATER
U-13

02-09-65
9-1383
0 1385
Id
1 1
72
235
10
NO
W
1510
10
4 9
500
SAS-1300Y- 177
V DRAINAGE
U-l

02-09-65
9-U03
0 1105
NO
1 1
71
1380
10
0 2
NO
147
ND
4 4
12
SAS-I300Y- 191
RIVER UATER
IHO

02-09-85
9-1392
0 1391
K)
0 14
8
3230
1 IB
W
1 9
Tl
"" W
7 r
124
SAS-13QQY- 194
RIVER UATER
U-12

02-09-65
9-1399
0 1101
M>
M>
10
3830
D 45
NO
»
II
NO
7 2
128
5AS-1300Y- 181
GROUOUATER
6-1

12-13-81
9-1342
0 1341
M)
K)
3
390
10
NO
10
5 1
W
4 8
100
SAS-13D0Y- IBS
GROUOUATER
G-l
6-1
12-13-61
9-1345
a 1347
W
K)
7 8
1780
NO
NO
M)
7 1
w
4 8
100
5AS-13D0Y- 164
GROUOUATER
G-3

12-I3-B1
9-1348
0 1370
K>
Ml
7.3
43 "
MJ
Ml
( 3
29
10
4 9
375
SAS-I300T- 1T8
GROUOUATER
6-2

02-09-65
9-1104
a 1108
NO
0 23
23
8370
10
M)
3 1
54
10
4 1
650
SAS-I3C0T- 199
GROUOUATER
6-4
6-Z
02-09-85
9-1109
a Ull
NO
0 21
11
5020
1 1
M)
H>
39
ND
4 0
850
SAS-I300T- 192 SUJFACE UATER
U-6

02-09-65
9-1384
D 1388
NO
21
tua
1980"
7 3
0 2
W
5078
W
5 0
no
SAS-1300T- 190 SURFACE WATER
U-9

02-09-65
9-1380
a 1362
NO
20
1200
5390
10
0 2
1 1
5510
ND
4 4
150
SAS-1300T- ITS SLRfACE UATER
u-n

02-09-65
9-1394
0 1398
W
33
1810
1580
5
K)
W
7810
NO
1 1
ITS
SAS-UOOT- 193 SUiFAtE WATER
U-7

02-09-85
9-1389
0 1391
NO
31
1470
7140
29
0 2
s 1
8210
Ml
4 4
40
SAS-1300V- 167 SURFACE UATER
U-2

02-09-®
9-1371
a 1373
w
201
3940
utaa
13
a 5
H)
373QD
Ml
1 t
STO
SAS-13D0r- 188 SUffACE UATER
U-4

02-09-85
9-1371
a 1374
M>
236
9580
2DDOO
IS
01
47
15700
M)
3 9
700
SAS-I300T- 189 SURFACE UATER
U-20
U-4
0Z-O9-85
9-1377
a 1379
10
214
9220
18200
24
a 3
W
44800
M>
3 7
750
LABORATORY DETECTION LIMITS





10
0 1
3
3
5
0 2
1
1
10


NOTE' Vatufi ihoan at *WJ In tht tablf tfittd for but not dtlectfdi actual valut Mr b* at or bclo* tfc* laboratory dttrctlon I»¦ 11
Valu» for Cdi Pb» and M in th* Uattr Quality Critiria For Aquatic Lift tr« baud on trillion* utinj a hardftM* valut ot 7S •?/!

-------
TABLE C-7
DATA fDH WATER SAtn.ES--0IS5O.UU) ItTALS
CELIOfi CHEMICAL WOttS UATEfl SAflPLE OAIA
SEICDIN. IHVESTIBATION REPORT
ctcn Hia job no. 1149420 oo oo
DISSOLVED METALS
ICTM.S VALUES IN ui/l
SPECIFIC
CONDUCTANCE
saitle una
TYPE
LOCATION
DUPLICATES DATE
TAG MISERS

At
Cd
Cu
Ft
Pb
H*
A»
2n
CN
pH
(uahot/ca)
sas-iloot- tea
6LAW
6-5

12-13-84
9-1350
0
1352

NO
M)
K)
14
ND
to
to
to
NT
7 0

SAS-uooT- zaa
BLAMC
W-21

02-09-85
9-1412
0
1414

M>
W
7 1
8 5
2.7
to
to
14
NT
7 0
	
SAS-I300T- ZGI
SLAW
W-22

02-09-05
9-1415
0
1417

M)
NO
4 2
W
Ml
NO
4 1
to
NT
7 0
...
SAS-I300Y- 161
SPRING WATER
W-15

12-13-84
9-13S3
0
1355
SO
(•tt)
10
to
44
M>
to
to
to
NT
62
175
SAS-1300Y- 167
SPRING WATER
w-u

12-13-64
9-I3S4

1356

NO
NO
to
310
10
to
to
to
NT
7 8
225
SAS-1300T- 163
SPRING UAIER
W-17

12-13-84
9-1359

1341

to
to
NO
350
Ml
to
4 4
10
NT
7 9
300
SAS-13Q0T- 191
SPRING WATER
U-13

02-09-as
9-1363

1365

M)
3
52
33
to
to
ND
1540
NT
4 9
500
SAS-1300Y- 197
UP DRAINAGE
IM

12-09-65
9-1403

IADS

W
0 22
14
1230
4 7
to
to
50
NT
4 4
42
SAS-1300Y- 194
HVER WATER
U-10

02-09-05
9-1392

1394

NO
0 18
2 7
245
to
to
to
11
NT
7 2
124
SAS-1300Y- 194
RIVER WATER
U-1Z

02-09-05
9-1397

1401

10
W
4
258
ND
0 3
10
5 5
NT
7 2
128
SAS-1300Y- 164
GROUNDWATER
6-1

12-13-84
9-1342

1344
50
(ttt)
ND
K)
344
10
NO
10
ND
NT
4 8
400
SAS-I300Y- 165
CROIHHMIES
6-4
G-l
12-13-84
9-1345

1347

W
W
10
295
to
to
to
to
NT
4 8
400
SAS-1300Y- 184
GSOUOUAIER
6-3

12-13-64
9-1346

1370

NO
»
N>
32
to
ND
to
34
NT
4 9
325
SAS-130Dr- 198
SKUOUATER
6-2

02-09-05
9-1404

1406

W
0.28
4 4
1340
1 9
t€
to
54
NT
4 1
850
SAS-I300I- 199
6BOUOUATER
6-4
6-2
02-09-05
9-1409

UL1

Ml
0 16
3
513
NO
W
to
29
NT
4 0
850
SAS-1300Y- 192 SURFACE WATER
W-fl

02-09-05
9-1364

1380

10
24
1110
2020
3 2
to
to
532D
NT
5 0
UD
SAS-I300V- 190 SURFACE WATER
W-9

52-09-65
9-1360

1382

NO
28
971
123
NO
ND
M)
4440
NT
4 4
450
SA5-I300Y- 195 SURFACE WATER
W-ll

02-09-05
9-1394

1396

tO
37
1900
900
1 9
to
to
0310
NT
4 4
175
SAS-I300Y- 193 SURFACE WATER
W-7

02-09-05
9-1309

1391

10
4 1
232
1340
S 7
to
to
1410
NT
4 4
40
SAS-1300Y- 187 SURFACE WATER
W-2

02-09-05
9-1371

1373

W
200
4040
6460
7
to
K>
WHlfl
NT
3 4
570
SAS-1300Y- 188 SURFACE WATER
W-4

02-09-05
9-1374

1374

M
241
9920
14400
3 4
0 3
to
46300
NT
3 9
700
SAS-1300Y- Iff? SRFACE WATER
W-20
W-4
02-09-05
9-1377

1379

ND
240
9490
144 DO
3 4
0.4
3 1
47800
NT
3 7
750
OR IWINE WATER STAWAROS







SO
10
1000
300
50
2
50
5000



WATER QUALITY CRITERIA FOR AOUATIC LIFE






440
0 16
5 4
—
1 95
0 2
2 47
47



LABORATORY DETECTION LIMITS







10
0 1
3
3
5
0 2
4
4
10


NOTE' Vjlulf thoan it *10* is ttit tibia atrt ttitid lor but not dttlcttdi ictuil volut uy bt it or btloa thi litaritorr dftlction Hut
Valuti lor Cd> Pbi led As In tki Watir Quality Crlttrla For Aquatic LIU ira batad on equation* mi a) i kardntsi valut of 75 ai/l

-------
Celtor Chemical Works
Mining Waste NPL Site Summary Report
Reference 3
Excerpts From Superfund Record of Decision,
Celtor Chemical Works, California, (Second Remedial Action);
EPA, Office of Emergency and Remedial Response,
EPA ROD R09-85/009; September 30, 1985

-------
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Inv^ortMAOi	€mw^#nev erd	4 ^ ®C9 -5
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			irz
©ERA Superfund	~ ~~
Record of Decision:
Celtor Chemical, CA
(Second Remedial Action, 09/30/85)

-------
RECORD OP DECISION
Remedial Alternative selection
SITE; Celtor Chemical Works, Hoopa, California
DOCUMENTS REVIEWED
My decision is primarily based on the following documents
that describe the cost-effectiveness of remedial alternatives for
the Celtor Chemical Works;
DESCRIPTION OP SELECTED REMEDY
- Excavation and off-site disposal of all soils
contaminated above site-specific action levels
at a RCRA-approved hazardous waste disposal
facility.
DECLARATIONS
Consistent with the Comprehensive Environmental Response
Compensation, and Liability Act of 1980 (CERCLA), and the National
Oil and Hazardous Substances Contingency Plan (40 C.P.R. Part 300),
I have determined that excavation and off-site disposal of all
soils contaminated above site-specific action levels at the
Celtor Chemical WorXs is a cost-effective remedy which provides
adequate protection of public healthi welfare, and the environment.
The State of California agrees with the selected alternative.
The remedial action I have chosen will require future
operation and maintenance to ensure its continued effectiveness.
These operations and maintenance activities are part of the
approved action and are eligible for Trust Fund monies for a
period of one year.
I have also determined that the remedial action selected is
appropriate when balanced against the availability of Trust Pund
monies for use at other sites. Pinally« the off-site transport
and secure disposition of the hazardous substances is more cost-
effective than other remedial actions and is necessary to protect
public health, welfare and the environment*
-	Celtor Chemical Works Remedial Investigation
-	Celtor Chemical Works Feasibility Study
-	Summary of Remedial Alternative Selection
-	Community Relations Responsiveness Summary
DATE
JUDITH E. ASTRES
Regional Administrator
EPA Region 9

-------
SOMMARY OF REMEDIAL ALTERNATIVE SELECTION
CELTOR CHEMICAL WORKS
HOOFA, CALIFORNIA
I. SITE LOCATION AND DESCRIPTION
The Celtor Chemical Works site is located in the northern
end of the Hoopa Valley in Humboldt County, California, (see
Figure 1). The 2.5 acre site is on reservation land of the Hoopa
Valley Indian Tribe, about 2 miles north of the town of Hoopa.
The main features of the site are the plantsite, a privately
owned pasture used for livestock grazing to the vest of the
plantsite# and a shallow gully that runs northward from the
plantsite to the Trinity River (see Pigure 2). Sulfide ores were
hauled to the Celtor Mill from the nearby Copper Bluff mine for
copper, zinc* and precious metal extraction. The plantsite
currently contains a number of concrete walls and slab floors
as remnants of the former ore processing operations.
Surrounding the mill are bare to partially vegetated slopes
that consist of native soil contaminated by ore and tailings.
Dirt roads crosB the site, and a gravel fishing-access road
passes through the lower (western) part of the plantsite area
separating the plantsite from the pasture. The grass covered
pasture, located below and west of the fishing-access road and
the plantsite, is used to graze cattle. The 500 foot long gully,
which runs to the north of the plantsite, is heavily wooded and
contains thick brush. This gully discharges into the Trinity
River, which, in this area, is classified as a scenic river
area under the National Wild and Scenic River System. The Trinity
is also considered an important fish resource, Including salmon
and trout spawning grounds.
In December,. 1964 the maximum historic flood for this area
was recorded. United States Geological Survey (USGS) and the
United States Army Corps of Engineers (USACE) records classify
the 1964 flood as greater than a 100-year event. Aerial
photographs, discussions with local residents, and a high water
mark indicate that in the site area the flood reached a height
of 321 feet above mean sea level. The lowest elevation of the
plantsite is 330 feet. Thus, all areas lower than the plantsite,
such as the pasture, at elevation 320 feet, and all of the gully,
may be impacted by a 100-year flood.
The predominant water bearing aquifer beneath the site is
a three to five foot thick bed of sandy gravel which rests atop
relatively impermeable unweathered phyllite bedrock. This highly
permeable and transmissive aquifer is located between 20 feet (at
the plantsite) and 60 feet (in the middle of the gully) below
the ground surface. A substantial amount of water, perhaps
greater than 10 cubic feet per second, flows in this aquifer in
a northerly direction into the Trinity River.

-------
-4
The structure nearest to the site is a home situated
approximately 500 feet to the south. One thousand two hundred
twenty (1,220) feet south of the site are approximately one
hundred hones which are part of the Norton Field Development.
Altogether, approxinately 900 residences are within three miles
of the site. Until as recently as 1985, residents of the Norton
Field Development, and other nearby hoaea, drank water froa a
community well which tapped into the saae ground water which
flows beneath the site. The well, which is located upgradient
(south) of the site was saapled by the United states Indian
Health Service (I8S), and was found to be free of inorganic
contamination, except for iron, which la believed to be a local
phenoaenon. All residents in the vicinity of the site now drink
water supplied from an upstream surface water source, except for a
cluster of six to ten hoaes which draw froa private wells located
further upgradient of the site than the Norton Field coaaunity
veil.
II. SITE BISTORY
The Boopa valley Indian Tribe is the owner of the Celtor
site. The Tribe's land is held in trust by the United States.
The Trlba leased the land in 1958 to the Celtor Cheaical
Corporation which processed sulfide ore taken froa the nearby
Copper Bluff Mine. A responsible party search conducted for EPA
in November, 1984 Indicated that ore processing aay have occurred
at the site prior to 1958, but there la no reliable documentation
to support this contention.
The plant, known as the Celtor Cheaical works Mill, is
believed to have used diasolved air flotation to extract copper,
sine, and precious metals froa the ore. The ore concentrates
were then trucked off-site for further processing, some aine
tailingo were stockpiled in the plantsite area. However, aost
were presumably sluiced down the gully to the Trinity River.
The tailings aay have been the cause of the nuaerous fish kills
for which th« California Department of Fish and Game cited the
Celtor Cheaical Corporation.
Beginning in 1960# the company became delinquent in its
royalty payments to tha Boopa Valley Indian Tribe. By 1962,
Celtor*s indebtedness to the Tribe had Increased to $23,592.87.
According to records from the United States Bureau of Indian
Affairs (BZA), mining and milling operations actually ceased
on June 2, 1962 and June 5, 1962, respectively. Finally, in
March of 1963, the BIA, as the trustee for the Boopa Valley
Indian Trlba, cancelled the leases of both the Copper Bluff
Mine and the Celtor Chemical Morks Hill.
After milling operations ceased, a very large pile of
tailings was reported to have been left standing on a sand and
qrivtl bar between the gully and the Trinity River, along with

-------
-5
th« callings that are known to have been left at the plantsue
area. The aforementioned flood of 1964 removed all traces of
any tailings that may have been on the sand and gravel bar.
The remaining tailings in the plant area, along with non-
specific releases of ore or tailings throughout the plantsite
area, are believed to be the cause of the acidic surface water
runoff and very elevated metals concentrations in the soils
throughout the plantsite area. These conditions were identified
by sampling performed by the State of California Department of
Health Services (DOBS) in July, 1901. The sampling occurred in
the same month that DOHS first discovered the site through an
ongoing California statewide abandoned industrial waste facility
survey. In August of that same year, the IBS submitted to the
United States Environmental Protection Agency (EPA) a Notification
of Baxardous waste Site under the Comprehensive Environmental
Response, Compensation and Liability Act of 1980 (CERCLA). In
Pebruary, 1982 the EPA Field Investigation Team performed
additional sampling at the site.
In April, 1982 the sits was placed on the California State
Priority List, and on December 30, 1982, the site was proposed
for inclusion on the National Priorities List (NPL).
On August 29, 1983, EPA wrote to the BIA, stating our intent
to perform sn initial Remedial Measure (XRM) at the site and
requesting BXA to either perform or sponsor the action. This
letter explained that EPA considered BIA a potential responsible
party at the site due to its rola as trustee for the Boopa Valley
Indian Tribe. The mill leas* stated that the site was to be left
in a condition that would not be hazardous to public health or
safety, a condition that Celtor had not complied with. The BIA
response stated that the matter should be elevated to a higher
level for resolution. Due to the impending winter rains, which
would have caused continued acidic surface runoff and health
threats, EPA performed the IRM action in December, 1983, prior to
the resolution of the responsible party issue.
During the IRM, all visibly contaminated material was removed
from the site. This material included all tailings, non-concrete
structures, and a portion of the adjacent pasture (see Figure 3).
In all, approximately 1,400 cubic yards o£ contaminated material
were taken to the IT Corporation Class I hazardous landfill in
Benicia, California, me total coat of this action was approxi-
mately 9337,000. After the contaminated soil was removed, the
fishing-access road was regraded and covered with fresh gravel.
Finally, a drainage culvert was installed at the north end of the
site*; and the site was fenced. All IRM activities were completed
on December IB, 1983. Plans were mada to return to the site
during tha next rainy season to perform the sampling necessary to
determlno if run-off or soils from the site or adjacent areas
still posed a health threat.

-------
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-------
-7
III. CURRENT SITE STATUS
On October 10, 1984, the Pinal Remedial Investigation/
Feasibility Study Work Plan received EPA approval. Remedial
investigation field work was completed on Pebruary 9, 1985,
and the final Remedial Investigation Report was released on
April 29, 1985. The results of the 177 surface and subsurface
soil samples, 32 surface water and ground water samples, and 16
air samples are discussed below.
In order to have a basis on which to evaluate the results of
the Remedial Investigation, criteria for evaluating the hazards
at the site had to be determined. Because no Pederal action
levels exist for defining hazardous concentrations of metals in
soil, the State of California, California Assessment Manual (CAM)
Total Threshold Limit Concentrations (TTLC) criteria for defining
hazardous aateriala were used. Water quality was evaluated on
the basis of the EPA One Bour National Ambient Hater Quality
Criteria for Protection of Freshwater Aquatic Life, 45 Federal
Register 79318 et seq., November 28, 1980 and 50 Pederal Register
30784 et seq., July 29, 1985 (WQCAL), as promulgated under the
Clean Water Act as amended in 1977 (CWA) and the EPA Maximum
Contaminant Levels (MCLs) or Primary and Secondary Drinking
water Regulations, 40 C.P.R. Part 141 and 49 Federal Register
24330 et seq., June 12, 1984 (DWRs), as promulgated under the
Safe Drinking water Act as amended in 1977 (SDWA).
The soil samples taken from the main plantsite to a depth of
20 feet contained cadmium, copper, lead and sine in concentrations
greater than the CAM TTLC criteria to depths of 2.5 feet. Elevated
concentrations of arsenic, copper, and sine were also found to
depths of 11.5 feet. These deeper concentrations were above
background levels, but were not necessarily greater than the CAM
TTLC criteria. The most significant elevated metals concentrations
in the plantsite were 124,000 milligrams per kilogram (mg/kg),
or parts per million (ppa), copper at the surface, 23,330 mg/kg
sine on the fishing access road surface, and 1,040 mg/kg lead,
also on the surface*
The gully was also found to be contaminated. The remedial
investigation field personnel observed a vein of tailings which
was approxlaately four feet wide and five feet deep. Again,
arsenic, cadmiusi, copper, lead, and sine were found at
concentrations exceeding the CAN TTLC criteria. Although
concentrations above background were found at depths up to 4.5
feet, maximum concentretiona were only found between the surface
and 2.5 feet. These maximum concentrations were 600 mg/kg for
arsenic, 310 mgA? for cadmium, 25,500 ag/kg for copper, 1,680
mg/kg for lead, and 62,100 mg/kg for sine.
A thin lens of contaminated material was found beneath the
clean fill that had been placed in the adjacent pasture after the
IRM. In this lens, 1.25 feet below the surface, arsenic, cadmium,

-------
-8
copper, lead, and zinc were found In elevated concentrations,
however, only lead, at 2,650 mg/kg, and zinc, at 11,200 mg/kg,
were above the CAM TTLC criteria.
During the winter months, water from many springs and seeps
travel through or beneath the plantsite. These springs either
emerge somewhere in the plantsite area and eventually collect
in the gully, or continue to travel beneath the plantsite Cor
eventual discharge into the Trinity River.
Sampling showed that these waters become contaminated as
they pass through or on top of the site. Water leaving the site
and in the gully was contaminated with cadmium, copper, lead,
iron, and sine above the MCLs, as well as, in some cases, the
more stringent WQCAL. No WQCAL for lead has been established.
Maximum concentrations found on the plantsite or in the gully
were 241 micrograms per liter (ug/L), or parts per billion (ppb),
of cadmium, 9,920 ug/L of copper, 16,600 ug/L of iron, 7 ug/L of
lead, and 48,300 ug/L of zinc. The pB of the water was as low
as 3.6. That value, however, is not lower than the CAM TTLC and
the Resource Conservation and Recovery Act as amended in 1984
(RCRA) criteria for definition of a hazardous material, which is
pB equal to or less than 2.
Sampling upstream and downstream of the gully's discharge
point into the Trinity River showed that the river was not
detectably impacted by water discharges from the gully. A worst
case analysis of the potential impact was conducted in the Remedial
Investigation Report. Assuming a first flush of contaminants from
the site entered the river during low flow, this analysis showed
that river impact would be unlikely because the projected dilution
of 1:500 (normal dilution is between lilOOO and 1:5000) would
prevent the water quality in the Trinity River from rising above
the WQCAL for more than a few hours.
Sampling during the remedial Investigation showed that ground
water beneath, and in th« vicinity of the site was not contaminated.
Thero w«re, however, elevated levels of iron in some of the samples,
but discussions with the Environmental Director of the Boopa
valley Business Council (BVBC), the representatives of the Boopa
valley Indian Tribe, and the IBS, indicated that this is due to
naturally elevated levels of iron in the local soils. In summation,
there does not appear to b« a ground water contamination problem
associated with the site.
On June 18 and 19, 1985, in response to community concerns
about noxious odors in the vicinty of the site, the EPA Technical
Assistance Team performed air sampling at the site. No detectable
concentrations of air pollutants relating to the reported sulfur
odor could be found. Bowever, there is a noticeable sulfur odor
in the area at times. If the odors are caused by the contaminants
at the site, implementation of the recommended alternative should
eliminate this odor nuisance.

-------
-9-
In summation, the Remedial Investigation found that the site
poses a threat to human healch and the environment from high
levels of arsenic, cadmium# copper, lead, and zinc in the soil.
Direct contact, especially ingestion of greater than 2 liters per
day, with contaminated water in the plantsite, roadway, or gully
areas also poses a human health and environmental threat.
IV. ENFORCEMENT ANALYSIS
A potential responsible party search completed for the EPA
in November, 1984 concluded that the Celtor Chemical Corporation
was a defunct company with no remaining assets or interests that
could be pursued for cost recovery. The BIA, as trustee for the
Hoopa Valley Indian Triba and the United States Department of the
Interior (DOI), the parent agency of the BIA, are the only other
potential responsible parties.
On August 29, 1983, prior to the IRM, EPA sent to BIA a
3007/104 Notice Letter which identified the BIA as a potential
responsible party and requested BIA to fund or perform the IRM.
On October 24, 1983, BIA responded and suggested that the matter
be elevated to BIA Headquarters. After EPA conducted the IRM,
a second Notice Letter was sent to the DOI in August, 198S
specifying our intent to take remedial action and requesting DOI
to fund or perform the remedial action. A meeting was held in
Washington, D.C. on September 19, 1985 to di'sucss the DOI's
status as a potential responsible party. At the meeting, the
DOI refused to contribute to or conduct the remedial action.
However, DOI agreed to discuss the matter further with EPA after
the cleanup was completed during cost recovery negotiations.
Results of ongoing discussions at the Headquarters level
regarding DOI's liability for sites on Indian lands that are
held in trust by DOI will be a key element in the resolution of
DOI's status at this site.
V. ALTERNATIVES EVALUATION
Ths following section summarises the alternatives evaluation
and recoaasnded alternative selection process as documented in
the Feasibility Study. All procedures are consistent with the
National Oil and Hazardous Substances Contingency Plan, 47 Federal
Register 31180 et seq., July 16, 1982 (NCP) and the Guidance on
Feasibility Studies Conducted Undsr CERCLA, EPA# June, 1985.
This section begins with the definitions of the remedial actions
that were evaluated then describes the site-specific action
levels thst were selected for the site. An alternative, consistent
with all relevant guidance, is then chosen. The steps in this
evaluation are technology development, initial alternative screening
and detailed analysis of alternatives. Finally, the results of
alternatives evaluation is documented.

-------
-15-
be in compliance with all other applicable EPA standards
(e.g., Clean Water Act, Clean Air Act, Toxic Substances
Control Act). Removal and treatment are in this category.
2.	Alternatives that attain all applicable or relevant Pederal
public health or environmental standards, guidance, or
advisories. Removal, encapsulation, and treatment all
fall into this category.
3.	Alternatives that exceed all applicable or relevant Pederal
public health and environmental standards, guidance, and
advisories. No alternatives are in compliance with this
category because it was not feasible to develop an alternative
that trould exceed all applicable environmental standards.
4.	Alternatives that meet the CERCLA goals of preventing or
minimizing present or future migration of hazardous sub-
stances and protect human health and the environment, but do
not attain the applicable or relevant standards. This
category may include an alternative that closely approaches
the level of protection provided by the applicable or relevant
standards. Capping falls into this category.
5.	A no-action alternative must be included.
A more detailed description of the alternatives mentioned
above is provided below:
1.	No-Action
2.	Capping - Partially demolish concrete structures (to
facilitate capping).
Excavate soils contaminated above action levels
from the pasture and gully, deposit in plantsite
area, and backfill pasture and gully with clean
soil.
-	Regrade all areas.
-	install surface and subsurface drainage systems.
-	install multilayer system of clay, synthetic
cover, and native'soil over contaminated material
in plant area.
-	vegetate site.
Install security fencing to protect cap and new
vegetation.

-------
-16-
3.	Removal - Demolish and remove structures,
-	Excavate soils contaminated above action levels
from all site areas.
-	Remove all soils to a RCRA-approved Class I
landfill.
-	Import clean fill as necessary.
-	Regrade and vegetate site.
-	Install security fencing to protect new
vegetation.
4.	Encapsulation
-	Demolish concrete structures and bury on-site.
-	Excavate soils contaminated above action levels
from all site areas.
-	Backfill pasture and gully with clean soil.
Encapsulate contaminated soils on-site.
-	Install surface and subsurface drainage systems.
Import clean fill as necessary.
Regrade and vegetate site.
Install security fence to protect new vegetation.
5.	Treatment
-	Demolish and bury structures on-site.
-	Prepare the site for a treatment facility.
-	Excavate soils contaminated above action levels.
-	Process soils contaminated above action levels
through the EPA Mobile Soils Flushing Unit.
-	Return clean material to excavated areas.
-	Add clean fill as necessary.
Remove contaminated sludges/waste to a RCRA-
approved Class I landfill.

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-26-
VIII. RECOMMENDED ALTERNATIVE
Section 300.68(j) of the NCP states that "The appropriate
extent of remedy shall be determined by the lead agency's
selection of the remedial alternative which the agency determines
is cost-effective (i.e. the lowest cost alternative that is tech-
nologically feasible and reliable and which effectively mitigates
and minimizes damage to and provides adequate protection of public
health, welfare, or the environment)". Based upon the Remedial
Investigation and Feasibility Study, EPA Region 9, the State of
California, the Boopa Valley Indian Tribe, the Bureau of Indian
Affairs, and the Department of the Interior agree that excavation
and off-site removal of all soil contaminated above site-specific
action levels is the most cost-effective long-term remedial action
necessary to protect human health and the environment. This
alternative fully complies with all relevant or applicable laws
and regulations.
No-Action was eliminated as a potential alternative because
it would not protect human health and the environment, based on
the Public Health Assessment conducted for the Feasibility study.
Capping was eliminated beause of the high probability of subsurface
water migration through the contaminated soil and off-site migra-
tion of contaminants. These contaminants could be carried to the
surface via the many springs in the area where they would pose a
human health threat. Encapsulation was also eliminated because
of probability that, over time, the many springs in the area
could damage the integrity of the encapsulation ceil, thereby
permitting contaminants to migrate to the surface and off-site.
Capping and Encapsulation have the added disadvantage of
requiring a permanent deed restriction on the property, since the
Inorganic contaminants present at the site do not degrade with
time. In addition, the entire cap or encapsulation cell may
require complete replacement every 30 years, the projected life
of the technology. For these reasons, Removal is selected as
the only remedial-action which la cost-effective and will assure
long-term protection of human health and the environment. Table 3
summarises the information presented in this document regarding
the various alternatives.
IX. OPERATION AMD MAINTENANCE
Projected O&M for removal, as for all of the alternatives,
is an initial one year p«riod of grounds maintenance. This
would include caring for surface vegetation, doing preventative
work on any surface water drainage systems, snd taking care of
erosion problems to assure that revegetated areas become properly
established. A fence will also be utilized for the first year
after remedial alternative implementation. The fence will help
to ensure that the vegetation is not disturbed while becoming
established. The total present worth of these OfcH activities
is $7,000.

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Celtor Chemical Works
Mining Waste NPL Site Summary Report
Reference 4
Excerpts From Superfund Site Close-out Report,
Celtor Chemical Works, Hoopa Valley Indian Reservation,
Humboldt County, California; EPA; September 29, 1989

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SUPERFUND SITE CLOSE OUT REPORT
Celtor Chemical Works
Hoopa Valley Indian Reservation
Humboldt County, California
I. summary of Site Conditions
Background
The Celtor Chemical works site, located in Humboldt
County, is approximately 2.5 acres of mountainous land at the
northern end of the Hoopa Valley Indian Reservation (attachment
1). The sites main features are: the plant site, a privately
owned pasture, and a shallow gully. The central part of the site
is located 1000 ft south and 800 ft east of the Trinity River.
The site was identified because of its potential for
contamination of groundwater and surface waters of the Trinity
River.
The plant was established in 1957 and processed sulfide
ore from nearby Copper Bluff Mine. The sulfide ore was processed
for copper, zinc and other precious metals. According to reports
wastewater was kept in settling ponds adjacent to the Trinity
River. In 1962, discharges from the ponds to the River were
reported, subsequently the Department of Fish and Game issued
Celtor citations for pollution and fishkills. Later that same
year, the plant was abandoned for unknown reasons.
Site Conditions
In 1981, the site was identified as part of an
abandoned site program industrial waste facility survey conducted
by the California Department of Health Services, Toxics
Substances Control Division (DHS). At the time of discovery the
aforementioned settling ponds were no longer visible and were
thought to have disappeared in the flood of 1964 (the pasture and
part of the shallow gully are below the 100-yr. flood plain for
that region). Random sampling and analysis was done at the site
by the DHS. The Indian Health services then submitted to the
Environmental Protection Agency (EPA), a Hazardous Waste site
Notification under CERCLA. The EPA Field Investigation Team
(FIT) conducted more sampling and analysis. The sampling done by
EPA FIT and the previous sampling conducted by DHS showed high
concentrations of heavy metals in the soil and in on-site surface
water. In April of 1982 the site was put on the California state
Priorities List and on December 30, 1982 the site was proposed
for inclusion on the National Priorities List (NPL). The NPL
listing was made final in September of 1983.
l

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In 1983, DHS did a more extensive analysis and
discovered that the surface samples had concentrations above the
California Assessment Manual Total Threshold Limit Concentrations
(CAM TTLC) for copper, zinc, cadmium, arsenic and mercury.
Surface water was shown to be acidic (pH as low as 2).
Because of the proximity of a housing development and
possible impact on the Trinity River, EPA conducted an Initial
Remedial Measure investigation and Focused Feasibility Study
(IRM/FFS). The IRM/FFS was completed on August 15, 1983; the
study concluded that the removing of all visible contaminants
(not including the concrete structures) and some of the topsoil
would be sufficient for the IRM. Approximately 1,400 cu. yds. of
contaminated material were removed by EPA, and the IRM was
completed on December 18, 1983. During the IRM more contaminated
material was found in locations which had not previously appeared
contaminated or had not previously been sampled. Due to the
discovery of more contamination, it was determined that a more
extensive Remedial Investigation was needed.
In October 1984, EPA began the Remedial Investigation.
The investigation included 177 surface and subsurface soil
samples, 19 surface water samples and three monitoring wells.
The soil samples were analyzed and the results compared to the
CAM TTLC levels as an indication of the extent of contamination.
The Remedial Investigation concluded that zinc,
arsenic, copper, cadmium and lead were present at high
concentrations on the site. Iron was also found at high levels,
but was not a contaminant of concern.
Analysis of groundwater samples showed that the
contaminants had not migrated to the groundwater aquifer.
Although site run-off was found to exceed both the Drinking Water
standard and the Federal Ambient Water Quality Criteria for
Aquatic Life, the dilution which it undergoes upon entering the
Trinity River (5000:1) is so great that it was concluded that the
River would not exceed standards as a result of low quality
surface water discharges (run-off) from Celtor.
Remedial Planning Activities
On June 28, 1985, a draft Feasibility Study was
released for a three week public comment period (June 28-July
19). The Feasibility Study (FS) gave a summary of site sampling
as well as a discussion of public health risk and a detailed
analysis of remedial alternatives available. The FS contrasted
the following remedial alternatives and their applicability to
the Celtor site: capping, encapsulation, excavation and off-site
removal,and no action. The FS concluded that no action at tL«i
Celtor site would result in a potential health threat to the
public from direct contact with contaminated soil and consumption
of contaminated onsite surface water or water from the gully.
2

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On December 9, 1987 the site was closed down for the
winter season. From December 9, 1987 until May 10, 1988, no
remedial activities took place at the site. On May 11, 1988
activities resumed and on July 9, testing within the exclusion
zone began. Excavation and stockpiling did not begin until
August 6, 1988 and the first off-site shipment went out on the
21st of August. On September 30, 1988 when the last shipment
left the site, backfilling and revegetation were started.
All backfilling and revegetation was completed on
October 14, 1988, marking the beginning of the one-year
post-remedial maintenance period. On February 28, 1989, the
Corps sent the Final Technical Report to EPA describing all of
the construction activities and the sampling data.
As of February, remedial contract costs were
approximately $ 4.9 million. Subsequent to completion of the
physical work, the U.S. Department of Labor (DOL) issued an
opinion that the Celtor contract inappropriately waived the
provisions of the Davis-Bacon Act relating to minimum wage rates.
The Corps is currently working with EHRT to assess the
implications of the DOL ruling and eventually pay the amount of
additional wages owed to workers. The Corps currently estimates
that up to $ 1.5 million is owed. Thus, final project costs will
not be known until the assessment is completed, probably sometime
in 1990.
II. Demonstration of OA/OC from Construction Activities
The remedial action contract was carefully reviewed by
the corps for compliance with all EPA and Corps quality
assurance/quality control (QA/QC) procedures and protocol.
All procedures and protocol followed for soil and air
sample analysis during the remedial action are documented in the
aforementioned Final Technical Report, Volume 1, Part 4, Final
Summary Chemical QC Report.
The site will be eligible for site delisting after the
five year site review during which additional samples will be
taken to confirm site cleanup.
in. confirmatory Sampling and Performance Monitoring Results
The contract for the remedial action, Specifications
for Construction contract, Solicitation No. DACW45-87-C-0384,
detailed a rigorous sampling and analytical program for the
remedial action. Specifically, the following sampling program
was required and implemented for 1) protection of the off-site
public, 2) protection of on-site workers, and 3) confirmation of
compliance with remedial action objectives:
* Daily perimeter air monitoring for total particulates,
respirable particulates, hydrogen sulfide, arsenic,
lead, cadmium, and copper.
5

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Daily personal air sampling of exclusion-zone workers
for arsenic, lead, cadmium and copper.
Hourly real-time on-site and perimeter air sampling for
total particulates.
Soil sampling of the backfill source for EPA priority
pollutants, organochloride pesticides and PCB's.
At any location where contaminants were detected
at a level higher than action levels, additional soil
was excavated and removed to the approved off-site
landfill. The removal of contaminated material, and
the subsequent confirmatory sampling of remaining
on-site soils, ensured that all contamination was
removed from the site according to the guidelines set
forth in the Quality Assurance Project Plan (QAPP).
Documentation of the results and accuracy of the
confirmatory sampling program is contained in the
aforementioned Final Technical Report.
Community Relations
Since the Celtor Chemical site posed a threat to the
residents of the Hoopa Valley Indian Reservation
through contamination of water supplies and exposure to
contaminated soils and was the object of public
concern, the Region's community realtions staff
conducted an active campaign to ensure that the local
residents were well informed about activities at the
site. Community relations activities included public
meetings and publication of progress fact sheets on a
routine basis.
Summary of Operations and Maintenance
The site cleanup complied with clean closure
requirements of the Resource conservation and Recovery
Act of 1976 (40 CFR Part 264.111). The site was
revegetated and post-closure maintenance was necessary
to insure that the vegetation survived. The
responsibility of operations and maintenance was
delegated to the Corps for a period of one year from
the completion of the remedial action. Until October
15, 1989, the Corps will continue to monitor the site
and perforin activities such as maintenance of the
perimeter fence and stabilization of vegetation cover.
It will be the federal government's responsibility to
assure the site's vegetation is maintained, but
ownership will continue to reside in the hands of the
Hoopa Indians.
6

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Celtor Chemical Works
Mining Waste NPL Site Summary Report
Reference 5
Telephone Communication Concerning Celtor Chemical Works;
From Maria Leet, SAIC, to Greg Baker, EPA Region IX;
October 19, 1990

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TELECOMMUNICATIONS
SUMMARY REPORT
SAIC Contact: Maria Leet Date: 10/19/90	Time: 11:35
Made Call X Received Call	
Person(s) Contacted (Organization): Greg Baker, RPM (415) 744-2221
Subject: Celtor Chemical Works
Summary: Remedial actions at the site hare been completed. A close-out report was completed on
September 3d, 1989. EPA is waiting for 5 years, at which time it can initiate de-lis ting of the site
from the NPL. EPA is also conducting a PRP search. It reopened the original search due to a
census of the statute of limitations, which is expected to hit in 1 to 2 years. EPA has a list of
names. However, due to the bankruptcy of companies and the potential shielding of owner/operator
assets from liability, EPA has not yet drawn any conclusions.

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Mining Waste NPL Site Summary Report
Cherokee County - Galena Subsite
Cherokee County, Kansas
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental Health and Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered and
endorsement by the U.S. government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-0025, Work Assignment Number 20.
A previous draft of this report was reviewed by Steve Sanders of EPA
Region VII [(913) 551-7578], the Remedial Project Manager for the
site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
CHEROKEE COUNTY - GALENA SUBSITE
CHEROKEE COUNTY, KANSAS
INTRODUCTION
This Site Summary Report for the Cherokee County - Galena Subsite is one of a series of reports on
mining sites on the National Priorities List (NPL). The reports have been prepared to support EPA's
mining program activities. In general, these reports summarize types of environmental damages and
associated mining waste management practices at sites on (or proposed for) the NPL as of February
11, 1991 (56 Federal Register 5598). This summary report is based on information obtained from
EPA files and reports and on a review of the summary by the EPA Region VII Remedial Project
Manager for the site, Steve Sanders.
SITE OVERVIEW
The Cherokee County Superfund Site is located in the Kansas portion of the Tri-State Mining District,
which includes the lead and zinc mining areas of Jasper County, Missouri, Cherokee County, Kansas,
and Ottawa County, Oklahoma (Reference 1, page 1) (see Figure 1 and Figure 2). Ore was first
discovered in the Tri-State Mining District in 1848 and it was first mined in the area of the Superfund
Site in 1876. Sphalerite (zinc sulfide) and galena (lead sulfide) were the important commercial
minerals. Cadmium was produced as a by-product of the lead-zinc smelting process. A smelter was
constructed along Short Creek in the 1890's and various smelting activities continued in the area until
1961 (Reference 1, page 2).
Cherokee County is located in the extreme southeastern corner of Kansas (Reference 2, page 4). The
Cherokee County Superfund Site contains six subsites: Waco area; Lawton area; Badger area, Galena
area; Baxter Springs area; and Treece area. According to EPA five Operable Units have been
identified in the Superfund Site: (1) alternate drinking-water supply for residents not currently
connected to Galena's municipal water system; (2) Spring River basin; (3) Treece subsite; (4) Baxter
Springs subsite; and (5) Ground-water/surface-water contamination.
Two Records of Decision (RODs) have been signed to date: one for the alternate drinking-water
Operable Unit (December 1987) and a second for the ground-water/surface-water contamination
Operable Unit (September 1989). The Treece subsite and Baxter Springs subsite Operable Units are
at the very early stages of the Remedial Investigation process. No investigation is anticipated in the
Spring River Basin Operable Unit. The alternative drinking-water Operable Unit and ground-
1

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Cherokee County - Galena Subsite
KANSAS
MISSOURI
CRESTLINE
OKLAHOMA
COLUMBUS

)M>US
c*es*
GALENA
SUBSITE
RIVERTON
CHEROKEE COUNTY
SITE BOUNOARY
GALENA
£MPM£
LAKE
BAXTER
SPRINGS
KANSAS
OKLAHOMA
C^SPOxESS
SUBSITE LEGENO
1	WACO AREA
2	LAWTON AREA
3	QaogERahea
* Galena suBSite
5	BAXTER SPRINGS area
6	TREECEAREA
FIGURE 1
SITE LOCATION
CHEROKEE CO KANSAS
GALENA SU8SITE-OUFS
grounowater/surface water
FIGURE 1. CHEROKEE COUNTY MAP
2

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Mining Waste NPL Site Summary Report
v'VlA rv
i	¦
' > •	j
, Hill* 1
y Vhaif acre
hum/r*« f

t
* ' -h
U_i		iOWEip/£ \ _ y
k ' ~ i :'A ¦ *
^AllM
t U , ^PfllNO^
rt , »\» > /dl H
— ®OohO*«» Of
™~™ caiina sumii
AmHJ.— .IGAUHA	SCMI M wu tl
cu* iiuiis
| s- j WINC WASH SluOT
!OMi
FIGURE 2. GALENA SUBSITE MAP
3

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Cherokee County - Galena Subsite
water/surface- water contamination Operable Unit are located in the Galena subsite and are discussed
in this Site Summary Report (Reference 1, Declaration).
The Galena subsite is characterized by surface mine wastes that directly impact the quality of the
shallow aquifer and the surface water (Reference 2, page 5). Studies and tests conducted in 1988 by
a group of Potentially Responsible Parties (PRPs) estimated that 550,000 cubic yards of waste rock
(including associated contaminated soils) and approximately 750,000 cubic yards of chat (gravel or
finer-grained material that has been processed to remove the metal sulfide minerals) are present within
the Galena subsite (Reference 2, pages 11 and 12). In addition, the PRPs estimated that historic
mining activities generated approximately 1.9 million cubic yards of surficial void space such as mine
shafts and pits (including 0.8 million filled with water) (Reference 2, page 12). Numerous surface
depressions exist from subsidence over collapsed mines (Reference 2, page 5).
Overall, approximately 900 acres in the Galena subsite has been disturbed by mining activities and are
covered with mining wastes. The mined area includes an estimated 3,000 shafts, including 580 open
shafts and surface collapses, many of which serve as direct conduits to the shallow ground water
Areas containing mine waste have sparse-to-no vegetation. Mining-waste deposits impact the quality
of the shallow aquifer. EPA investigations conducted in 1986 and 1987 found both the shallow
aquifer and surface water near the Galena subsite to be contaminated with high concentrations of
metals (primarily cadmium, selenium, and zinc) (Reference 2, page 5).
The City of Galena (population 3,500) is surrounded by the mine-waste area with many residences
adjacent to mine-waste piles. An additional 1,050 people live within the subsite but outside the City
limits. Residences and businesses who obtain their water supply from the City of Galena do not face
a health risk from this source, but residents outside of the City are at risk because their water supply
is from the contaminated shallow aquifer. The land is primarily rural, and is used for livestock
grazing and crop production (Reference 2, pages 4 and 5)
OPERATING HISTORY
Ore was first discovered in the Tri-State Mining District in 1848 The first significant lead and zinc
mine in Kansas was in the City of Galena, where ore was discovered in 1876. Sphalrite (zinc sulfide)
and galena (lead sulfide) were the ores of interest, and cadmium was produced as a by-product of
smelting. Pyrite and marcasite (both iron disulfide minerals) constituted about 5 percent of the
mineralized areas (Reference 2, page 5).
4

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Mining Waste NPL Site Summary Report
Lead and zinc mining flourished from the late 1800's through the 1940's. The peak production
within Cherokee County occurred in 1926, when 28,000 tons of lead and 126,000 tons of zinc were
produced. Production ended in Galena in the early 1920's. Mining activity decreased in the 1950's,
and many mines were closed. Mining revived in the 1960's, but all mining ended in 1970 with the
closing of the Swalley Mine near Baxter Springs (Reference 5, page 1).
A smelter was built along Short Creek in the 1890's. The area near the original smelter was used for
various smelting facilities until 1961, when the remaining facility was converted to produce sulfuric
acid (Reference 5, page 1).
Ore in the Galena district is typically found in veins 80 to 100 feet below the surface, which
permitted many small, shallow mining operations to flourish Exploration and mine development
were accomplished by excavating vertical shafts to locate the ore body, then excavating outward along
the ore vein, using a modified room-and-pillar method. The use of vertical shafts and the subdivision
of leases into small, sublease mining plots result in a high density of mine shafts in the subsite.
Several mines have collapsed, forming subsidence craters of varying sizes and shapes. Many circular
subsidences are less than 75 feet in diameter, while others measure several hundred feet along the
longest dimension. A ground level difference of 20 to 40 feet is common in the subsidences within
the subsite, although some (filled with water) may be deeper. In addition, over 350 open shafts are
accessible in (and around) Galena (Reference 1, pages 2 through 4; Reference 2, pages 5 and 6).
Large areas of the subsites are covered by mine wastes. The wastes include bullrock, dump material,
and chat. Bullrock and dump material are mostly coarse material and uneconomic ore removed from
shafts and mine workings during excavation and mine development. The bullrock and dump material
remain near many of the open pits, shafts, and subsidences (Reference 2, page 6).
SITE CHARACTERIZATION
The Phase I Remedial Investigation Report for the Galena subsite (April 1986) indicated that the
potential exposure pathways of humans to site contaminants included ingestion of ground water,
surface water, soils, fish and wildlife, and crops irrigated with contaminated ground or surface water;
dermal contact with ground and surface water and mining wastes; and inhalation of airborne
particulates (Reference 5, page 112). Contaminants of concern include cadmium, lead, and zinc
(Reference 2, page 13). Site Investigations and the Feasibility Studies for the ground- and surface-
water remediation determined the primary human health risk was presented by ingestion of shallow
ground water and ingestion of surface mining wastes. Environmental risks included contamination by
5

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Cherokee County - Galena Subsite
heavy metals of surface waters, including Shoal Creek, where one or more State-designated
endangered species exists (Reference 4, page 8).
EPA began its investigation of the Galena subsite in 1985. Additional investigations were carried out
in 1986 and 1987 (Reference 1, page 4). A group of PRPs collaborated in a study to determine the
amount of waste material remaining on the site in 1988.
Ground Water
Two aquifers exist in the Galena area, a shallow water-table aquifer and a deeper, confined aquifer.
The shallow aquifer includes strata from the Warsaw, Burlington-Keokuk, and Fern Glen Limestone
formations. The three limestone formations range in thickness from 0 to 200 feet. Where the strata
are massive, there is little water yield; but in areas where solution channels, breccia, and fractures
occur, the yields are adequate to good (Reference S, page 5). Over 1,000 residents used the shallow
aquifer as their primary source of potable water (Reference 3, page 4). The deep aquifer is the
source for municipal ground-water supplies (including the Galena municipal wells, which are about
1,200 feet deep) in the site area. The deep aquifer includes Cotter-Jefferson City Dolomite, the
Roubidoux Formation, and the Gasonade Dolomite formations. The Roubidoux formation is the most
productive zone of the deep aquifer (Reference 5, pages 5 and 29).
The hydraulic separation between the shallow and deep aquifers within the Galena subsite has not
been completely defined. In some cases, the confining layers between the aquifers has been breached
by wells (some unused) drilled into the deep aquifer. Six deep wells (of varying ages) have been
located in the subsite, and there may be more Several could be potential conduits for migration of
contaminated shallow aquifer water into the deep aquifer (Reference 3, page 4).
Mining activities have changed the geohydrology of the area by creating underground cavities, surface
subsidence, and diversions due to mine wastes on the surface. These actions have enhanced surface-
water infiltration into the shallow aquifer; and in some cases, entire flows have been diverted into the
ground-water system (Reference 3, page 6).
Oxidation of sulfide minerals in the area result in an acid sulfate geochemical system. When
oxygenated ground water contacts the metallic sulfide ores in the mines and mine wastes, sulfuric acid
is produced and metal ions are mobilized as dissolved compounds. This metal-laden acid mine
drainage has contaminated the shallow aquifer and filled mine shafts (as well as surface water)
(Reference 5, pages ES-3 and 36).
6

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Mining Waste NPL Site Summary Report
Ground-water samples collected (in July and August 1985) from the shallow aquifer in the Galena
subsite found maximum concentrations of cadmium [180 parts per billion (ppb)], chromium (120
ppb), lead (230 ppb), manganese (3,400 ppb), nickel (270 ppb), selenium (24 ppb), and zinc (15,000
ppb) in excess of Primary Maximum Contamination Levels (MCLs) or other standards for drinking
water (Reference 2, page 9a). From the 22 wells sampled, 4 wells exceeded the MCL for cadmium,
3 wells for nickel, and 2 wells for zinc (Reference 5, page 119). Wells downgradient of mined areas
showed higher levels of zinc than upgradient wells, a function of zinc's relatively high mobility and
high concentration. Other metals showed little or no difference, which was attributed to neutralization
of acid ground water by contacting naturally occurring limestone materials or mixing with alkaline
ground water (which, in turn, would cause metals to precipitate out) (Reference 5, pages 45 and 50).
A sample from the deep aquifer showed that all constituents met Primary and Secondary Federal
Drinking Water Standards (DWSs) (Reference 5, page 50).
Surface Water
The Galena subsite is drained by Spring River, Short Creek, Shoal Creek, and their tributaries. The
major drainage basin is the Short Creek Watershed, which flows east to west through the northern
portion of the Galena subsite before entering Spring River. Two downgradient wells located close to
the abandoned mine workings had pH levels below 6.5 (Reference 5, page 38). Most of the drainage
into Short Creek from the subsite is via Owl Branch and Tributary A. Tributary C, whose
headwaters are in chat-covered areas, drains the southwestern portion of the site before discharging to
Spring River. In addition, runoff from small northern and southern sections drains directly to Spring
River and Shoal Creek, respectively (Reference 5, page 57). In addition, Empire Lake, formed by
adjacent dams on Spring River and Shoal Creek, is located 3 miles west of Galena (Reference 5, page
57).
Mining activity changed the hydrology of the area by creating underground voids, subsidences, and
diversions due to mine wastes on the surface These actions disrupted the normal surface drainage
and depleted the vegetation, thereby enhancing infiltration of surface water into the ground-water
system. In some cases, the entire flow in a surface stream, such as Tributary A along "Hell's Half
Acre," is captured by a subsidence or shaft, directing it into the shallow aquifer. Nearly all of the
rain over much of the area covered by mine wastes infiltrates into the ground, due to its highly
permeable condition and the blocked surface drainage pathways. The shallow ground water, in turn,
recharges the major Creeks (such as Short Creek) (Reference 3, pages 4 through 6).
Sediments in Spring River, Short Creek, and the upper reaches of Shoal Creek are typically coarse
granular materials originating from the mined area (Reference 5, page 57). Acid mine drainage,
7

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Cherokee County - Galena Subsite
runoff from the waste piles, and contaminated ground-water discharge to the streams contributes to
the contamination of surface water (Reference 2, page 9). Surface waters within the Galena subsite
are not considered drinking-water sources and were not compared to Primary or Secondary DWSs, or
to ambient criteria for the protection of human health (Reference 5, page 120).
Analysis of samples taken from the Tributaries to Shoal Creek (July and August 1985) showed
concentrations of lead, zinc, and cadmium exceeding both acute and chronic water-quality criteria for
aquatic life. Shoal Creek is of special concern with respect to potential environmental effects,
because natural caves near Shoal Creek provide a critical habitat for one or more species of
Salamanders listed as endangered by the State of Kansas (Reference 2, page 10; Reference 3, page 3-
57).
Short Creek was the most impacted stream in the area. In Short Creek, under low flow conditions,
zinc and cadmium concentrations increased from below detection limits upstream to 25,000 ppb
downstream; cadmium increased from below detection limits to 150 ppb; lead was Not Detected
(ND). Subsurface recharge of Short Creek by mine water was suggested as the probable contributor
of elevated zinc and cadmium; lead was apparently precipitated on entering Short Creek (Reference 5,
pages 66 and 69). Under high-flow conditions in Short Creek, most metals decrease in concentration
as flow is diluted by runoff from undisturbed areas (total loadings of metals are higher, however)
(Reference 5, page 72). Cadmium, copper, lead, and zinc concentrations exceeding acute (short-term
effects) criteria in two or more samples (sampled July and August 1985). Cadmium (in 14 samples)
and zinc (in 15 samples) concentrations exceeded the criteria from Short Creek. Cadmium and zinc
concentrations exceeded the acute criteria in 28 and 60 percent of the samples analyzed, respectively
(Reference 5, page 120). Metals were at low concentrations in Empire Lake (total lead averaged 10.5
ppb, zinc averaged 340 ppb, and cadmium averaged 2.5 ppb) (Reference 5, page 74).
Sediments of the streams and Empire Lake show elevated levels of lead, zinc, and cadmium, with
Short Creek sediments being most contaminated. Short Creek contamination was due to the presence
of mining waste eroded into the stream and/or chemical precipitation (Reference 5, pages 76 and 78).
Air
Ambient airborne particulate samples were collected during a 14-day period in August and September
1985 (Reference 4, page 6-5). None of the samples collected had Total Suspended Particulate (TSP)
concentrations exceeding the Primary TSP National Ambient Air Quality Standard (NAAQS) of 260
micrograms per cubic meter 0-ig/m3) (Reference 4, page 6-11). The data indicated that average TSP
8

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Mining Waste NPL Site Summary Report
concentrations in the Galena area are in the high range for rural areas, but within the low range for
urban areas (Reference 4, page 13).
The samples were analyzed for lead and 33 other elements by X-ray Fluorescence (XRF). There are
no EPA or State standards for airborne elements except lead (Reference 4, page 6-16). The Primary
and Secondary NAAQS for lead (and its compounds) is 1.5 /ig/m3, the maximum arithmetic mean
averaged over a calendar quarter. Although direct comparisons cannot be made because the sampling
period was for only 14 days, lead concentrations are considerably lower than l.S /ig/m3. Mean lead
concentrations collected during the sampling period were found to be 0.119 film3 with a high of 0.25
Uglm3 (Reference 4, pages 6-17 and 6-18). Average lead concentrations from the National Air
Monitoring Network range from 0.1 to 1.0 fig/m3 for rural areas and from 0.5 to 10.0 uglm3 for
urban areas (Reference 4, page 6-20). The data show this area to be in the low rural range. The
maximum concentrations for other elemental metals were listed as: iron, 2.276 uglm3; manganese,
0.553 /ig/m3; copper, 0.825 /ig/m3; silver, 0.040 /ig/m3, zinc, 0.224 /ig/m3; cadmium, 0.056 /ig/m3;
chromium, 0 014 /ig/m3; nickel, 1.120 /ig/m3; barium, 0.400 /ig/m3; and arsenic, 0.010 /ig/m3
(Reference 4, page 6-17).
Soils
The Galena subsite consists of thin and rocky soils, with pH values ranging from 5.0 to 6.0. During
sampling, the investigation team found the soil contained chert fragments, with samples below 12
inches consisting largely of cherty gravel (Reference 5, page 53).
Previous investigations in the early 1970's concluded that elevated concentrations of heavy metals in
the soil exist in the vicinity downwind of the former Galena smelter (Reference 5, pages 53 and 54)
The Phase I Remedial Investigation, conducted in July and August 1985, hypothesized that elevated
concentrations of lead, zinc, and cadmium in surface soils was a result of deposition of airborne
contaminants from the former smelter. The levels of lead, zinc, and cadmium showed marked
decreases with increased distance from the smelter. Lead in surface soils varied from 510 to 68
(ppm), zinc from 1,100 to 230 ppm, and cadmium from 12 to 3 ppm. The source of the metals may
be fall out from smelter emissions (Reference 5, page 54). A relationship also existed between lead,
zinc, and cadmium concentrations and soil depth. Concentrations of those metals decreased as soil-
sample depth increased. Lead samples were as much as 13 times greater in shallow (0 to 6-inch) than
in deep (12- to 18-inch) soil samples. Zinc and lead showed less disparity (indicating higher mobility
of cadmium and zinc). Background soil samples contained lead, zinc, and cadmium but
concentrations varied with location, not sample depth (Reference 5, page 54).
9

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Cherokee County - Galena Subsite
Aquatic Life
Samples of game and forage fish were also collected at two areas in Empire Lake, 2.3 miles
downstream from mining-waste piles. Results suggested that bioaccumulation of metals is not
occurring to any extent in game fish from the Lake, and that the quantity of metals in for:_e and
game fish collected in Empire Lake is similar to amounts in forage fish collected from various
locations in Kansas (Reference S, pages 88 and 93).
In 1980, the Kansas Department of Health and Environment (KDHE) concluded that the Spring River,
from the confluence of Short Creek to the Kansas-Oklahoma border, was stressed by drainage from
lead-zinc mining in Missouri and Kansas. KDHE cited an "almost total absence of biota in Short
Creek and reduced diversity and absence of several pollution-sensitive aquatic organisms" from the
lower reaches of the Spring River (Reference 3, page 3-42).
ENVIRONMENTAL DAMAGES AND RISKS
Five exposure pathways were quantitatively assessed in the ground-water and surface-water Operable
Unit Feasibility Study. These include ingestion of contaminated ground water; incidental ingestion
and dermal absorption of surface water during recreational use (i.e., while swimming); incidental
ingestion of surface solids; and ingestion of fish from contaminated surface water (Reference 3, page
3-2). Other exposure pathways were not assessed (dermal absorption of metals through direct contact
with contaminated soils and inhalation of metals during swimming and showering in contaminated
water), as they were considered small exposures in comparison to other pathways. Ingestion of
contaminated food crops was not considered due to a lack of data regarding concentrations of
contaminants in crops. Finally, exposure through inhalation of contaminated, airborne particulates
was excluded because the focus was on surface water and ground water (Reference 3, pages 3-2 and
3-3).
Approximately 510 households (1,050 residents) outside of the City of Galena used private wells in
the shallow aquifer for their drinking water. These wells were obtaining water from the same
geologic formation that had previously been mined (Reference 2, page 9).
REMEDIAL ACTIONS AND COSTS
All mining activities in Cherokee County ended in 1970. A ROD (December 1987) was finalized for
the alternate drinking-water Operable Unit and for the ground-water/surface-water Operable Unit
(September 1989). The Treece subsite and Baxter Springs subsite Operable Units are in the very
10

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Mining Waste NPL Site Summary Report
early stages of the Remedial Investigation. According to EPA no investigation is anticipated in the
Spring River Basin Operable Unit.
Alternative Water Supply
The selected remedial action would provide an alternative water supply for residents using private
wells, which currently supply drinking water from the contaminated shallow aquifer. According to
the ROD, when the remedial activity is implemented fully, water will be distributed from the City of
Galena's deep aquifer wells through a pipeline network that will reach all 408 homes, farms, and
businesses within the subsite. The city's two existing wells were to be rehabilitated (if possible) to
provide additional capacity for the expanded system. The rehabilitation work includes: (1) replacing
the upper well casing; (2) replacing pumps to achieve higher pumping capacity; (3) upgrading the
wellhead facilities; and (4) adding chlorination facilities. The remedy called for a pipeline network to
be constructed to supply the additional service areas, which include the West, Lowell, North, and
South service areas. If property owners agree, the existing shallow wells will be plugged (Reference
1, page 23). Present worth capital cost was estimated in 1987 to be $5,300,000, and annual
Operation and Maintenance (O&M) costs were estimated at $100,000 (Reference 1, Abstract and page
26).
Ground Water/Surface Water Remediation
As described in the ROD, the selected remedy includes four components:
•	Mine, characterize, and selectively place mine wastes (chat and waste rock) in open
subsidences, pits, and underground workings. This should eliminate direct exposure and
ingestion of wastes and reduce further contamination of ground and surface water.
•	Divert and rechannel certain surface drainages (including Tributary A) to prevent surface-
stream capture by shafts and subsidences. This should reduce shallow aquifer recharge.
•	Recontour (to eliminate closed basins and low spots) and vegetate up to 600 acres to the extent
possible. Together with diversion and channelization, these actions should minimize shallow
aquifer recharge through infiltration and control erosion.
•	Investigate and, as necessary, repair or plug wells penetrating the deep aquifer. This is
intended to protect against contaminant migration from the shallow aquifer and mining-related
activities (Reference 2, page 19).
11

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Cherokee County - Galena Subsite
Costs for the remedial action were estimated in 1989 to be from $5.8 to $12.4 million ($8.3 million
was the single-value estimate). This figure assumes a 30-year life cycle and included contingencies.
Annual O&M costs were estimated to be $14,963 (including contingencies) (Reference 2, Table 7).
CURRENT STATUS
Remedial activities for the Alternative Water Supply Operable Unit are being designed, and
construction of water tanks is complete. Remedial activities for the Ground-water/surface-water
Operable Unit are currently being designed. An Administrative Order on Consent was signed, in
May 1990, between the PRPs and EPA to conduct Remedial Investigations of the Treece subsite and
Baxter Springs subsite Operable Units. The investigation at these Operable Units is in the beginning
stages, and soil sampling will begin in the spring of 1991. According to EPA, Investigations are not
anticipated for the Spring River Basin because the environmental problems at this Operable Unit are
being addressed in the Ground-water/surface-water Operable Unit.
12

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Mining Waste NPL Site Summary Report
REFERENCES
1.	Record of Decision for the Cherokee County Superftind Site - Alternative Water Supply Operable
Unit; EPA Region VII; December 21, 1987.
2.	Record of Decision for the Cherokee County Superfund Site - Ground-water/Surface-water
Operable Unit; EPA Region VII; September 18, 1989.
3.	Ground-water and Surface-water Operable Unit Feasibility Study, Galena Subsite, Cherokee
County Site, Kansas - Final Draft; EPA Region VII; February 26, 1988.
4.	Phase I Remedial Investigation Report, Air Quality Supplement, Cherokee County, Galena Subsite
- Final Draft; EPA Region VII; August 1, 1986.
5.	Phase I Remedial Investigation Report, Cherokee County, Galena Subsite - Final Draft; EPA
Region VII; April 23, 1986.
13

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Cherokee County - Galena Subsite
BIBLIOGRAPHY
Curtis, Glen, (EPA Region VII). Personal Communication Concerning Cherokee County - Galena
Subsite with Maria Leet, SAIC. August 3, 1990.
EPA Region VII. Alternative Water Supply Operable Unit Feasibility Study, Galena Subsite,
Cherokee County Site, Kansas - Final Draft. November 4, 1987.
EPA Region VII. Ground-water and Surface-water Operable Unit Feasibility Study, Galena Subsite,
Cherokee County Site, Kansas - Final Draft. February 26, 1988.
EPA Region VII. Phase I Remedial Investigation Report, Air Quality Supplement, Cherokee County,
Galena Subsite - Final Draft. August 1, 1986.
EPA Region VII. Phase I Remedial Investigation Report, Cherokee County, Galena Subsite - Final
Draft. April 23, 1986.
EPA Region VII. Record of Decision for the Cherokee County Superfund Site - Alternative Water
Supply Operable Unit. December 21, 1987.
EPA Region VII. Record of Decision for the Cherokee County Superfund Site - Ground-
water/Surface-water Operable Unit. September 18, 1989.
Sanders, Steve, (EPA Region VII). Personal Communication Concerning Cherokee County - Galena
Subsite with Mark Pfefferle, SAIC. January 25, 1991.
14

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Cherokee County - Galena Subsite
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From Record of Decision for the Cherokee County Superfund Site -
Alternative Water Supply Operable Unit;, EPA Region VII; December 21, 1987

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united Statu
E-vironm«rtai Protection
Agancy
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$EPA Superfund
Record of Decision:
Cherokee County/Galena, KS

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OPERABLE UNIT REMEDIAL ALTERNATIVE SELECTION
SITE NAME
Cnerokee County Site - Galena Subsite
Cherokee County, Kansas
STATEMENT Of PURPOSE
Tms decision aocument represents the selected remedial action for the
alternative water supply operable unjt developed in accordance with the
Comprehensive Environmental Response, Compensation and Liability Act of 19tiQ
(CEKCLA), as amended by the Superfund Amendments and Reauthorization Act of
1986 (SARA), and to the extent practicable, the National Contingency Plan (NCP).
The State of Kansas has concurred on the selected remedy.
STATEMENT OF BASIS
Tms decision is based upon the administrative record. The attached
index identifies the items wnich comprise the administrative record.
DESCRIPTION OF THE SELECTED REMEDY
The Galena subsite is one of six subsites within the Cherokee County site.
It has been divided into two operable units, alternative water supply and
ground water/surface remediation. This decision document addresses the
alternative water supply. The second decision document Is expected to be
completed in the second quarter of FY-88.
The selected remedy provides for collection of water from the Roubidoux
aquifer through existing wells owned by the City of Galena and the distribution
of that water through a pipeline network to the houses, businesses and farms
within the subsite, but outside of the Galena municipal water system. The two
wells will need to be rehabilitated in order to provide the necessary water.
A new well will need to be drilled if the existing wells cannot be rehabilitated.
The remedy includes the construction and equipment necessary to set-up a water
supply to this area.
DECLARATIONS
Consistent with the Comprehensive Environmental Response, Compensation
and Liability Act of IS6U, as amended, I have determined that the
provision of an alternative water supply to the residents of the Galena subsite
of the Cherokee County site, whose primary source of drinking water is the
contaminated shallow aquifer, 1s a cost-effective remedy, consistent witn
permanent remedial action for the site and provides adequate protection of public
health, welfare and the environment. The remedy selection procedure and the
selected remedial action comply with the provisions of the Superfund Amendments
and Reauthorization Act of 1986. The selected remedy Is not inconsistent witn
the National Contingency Plan, 40 CFR §300, and is a component of a total remedial
action for the site- The State of Kansas has been consulted and concurs with
the selected remedy.
Date
idmmistrato

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#EPO*T DOCUMENTATION 1 *i>z»r *o 	
PAGE :?V 5-C j/?0 -33/OIj
> I **c 0-««> I a- N3
4 r.|l« J*d
StiPEaF'JND RECORD OF DECISION
i
14/ i./ 3 '
herokee County/Galena, KS

First Remedial Action

T AulHOrttl
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'J.S. Environmental Protection Agency
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11 AMtract (Limit 100 worm)
The Cherokee County site, the Kansas portion of the Tti-State Mining District, is
located in the extreme southeastern corner of Kansas. The Galena suDsite, one of 3-.x
subsites identified within the Cherokee County site, encompasses 18 mJ. The Galena
subsite is characterized by surface mining waste features thae impact the quality of t-e
shallow ground water aquifer. This aquifer is a primary source of drinking water ft:
approximately 1,050 people. Remains from past mining activity at the subsite inci-ice:
large areas covered by mine and mill wastes, water-filled subsidence craters, and ::e-
mme shafts. EPA investigations of the Galena subsite conducted in 1986 and 195"
demonstrated thae the shallow ground water aquifer and surface water are eontan-atet
with elevated concentrations of metals. Due to the concern for the health of perso.-j
drinkinq this water, EPA Region VII conducted a removal action and installed water
treatment units on these wells. This removal action was considered a temporary
protective measure. The primary contaminants of concern observed in the private wel.s
include: cadmium, lead, selenium, and zinc.
The selected remedial action for this site provides for collection of water from t-e
aquifer through existing wells owned by the City of Galena with subsequent cSist:::-t.
of that water through a pipeline network to 418 houses, businesses, and farms outs::e :i
(See Attached Sheet}
17. Oocumcm Aawrdt * Ownnn
Record of Decision
Cherokee County/Galena, KS
First Remedial Action
Contaminated Media: gw
y.flanfflVMiMfiM*Ti.Clls (cadmium, lead, selenium, zinc)
e. COSATI NM/Siim
AvMtatriity IIIIIOIW	It. tavntr CtM* (THm Amm)	21 mo of °i«, i
None	- -
Iwynty CUM (T*»% »•««>	22 »"c*
None
(S«t ANtU^SI in	S#»	Isv^M	O^TtOWAL '0** .* ;2

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jgy&D/R07-88/010
jf^okee County/Galena, KS
y^rst Remedial Action
26. ABSTRACT (continued)
the Galena municipal water system but within the subsite. Additional capacity for the
expanded system will be rehabilitated to provide additional capacity for the expanded
system. If rehabilition becomes infeasible due to unforeseen onsite technicalities, a
new deep aquifer well may be drilled to provide additional waters. The remedy includes
acquiring the construction and equipment necessary to setup a water supply to this
area. The estimated present worth cost for this remedy is $5,300,000 with annual 06.M of
$100,000.

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ROO J)£CI SION SUMMARY
CHEROKEE COUNTY SITE - GALENA SUBS ITS
CHEROKEE COUNTY, KANSAS
INTKUDUCTIUN
Tne purpose of cms document is to describe the remedy that the U.S.
Environmental Protection Agency (EPA) has selected to implement at tne Galena
suosite of tne Cherokee County site. This document also describes the
decision-making procedures that were followed in select*ng this remedial
action, which provides an alternative water supply for residents living within
tne subsite.
The remedial action oas been selected to remedy an environmental problem
potentially affecting the health of residents living within the subsite.
Tms action is one part of an entire response action for remedying an uncontrolled
site containing hazardous substances. As it is only part of the whole action,
this is referred to as an "operable unit" remedial action. Operable units
must be consistent with the final remedy for a site and mjst be cost-effective
according to the Superfund Amendments and Reauthorization Act of 1986 (SARA).
This action is consistent and cost-effective with the site-wide remedy.
The decision-making processes regarding the Cherokee County site began
witn preliminary investigations, which led to the Inclusion of the site
on the National Priorities List (NPL) for cleanup of releases or threatened
releases of hazardous substances. The site was separated into six subsites
for further investigation and eventual cleanup.
A remedial investigation (RI) and an operable unit feasibility study
(QUFS) conducted at the Galena subsite led to the conclusion that the shallow
ground water aquifer contains levels of metals above primary maximum contaminant
levels (MCLs) established by the Safe Drinking Water Act. Approximately 1,050
people wno live witnin the Galena subsite use this contaminated shallow aquifer
for their sole source of drinking water. The decision to provide these people
with an alternative drinking water supply is based on the known release of
hazardous substances Into the shallow ground water aquifer, which is primarily
the result of prior mining activities conducted at the subsite and degradation
of the mining wastes over the past 100 years. The following discussions explain
procedures EPA used in making this Record of Oecision (R00).
SITE LOCATION AND DESCRIPTION
Tne Cherokee County site 1s the Kansas portion of the Tr1-State Mining
District, which includes the lead and zinc mining area 1n Jasper County,
Missouri, Cherokee County, Kansas and Ottawa County, Oklahoma. Cherokee County
is located in the extreme southeastern corner of Kansas.
The Galena subsite is one of six subsites Identified within the
Cherokee County site. The Galena subsite encompasses 18 square miles and
includes the communities of Galena, Lowell and surrounding homes, farms

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2
and businesses (Figure 1). Approximately 1.050 people live outside tne
Cu> of Galena. Tnese residents ootain drinking water from private snallo*
aquifer wells ranging from 2U to ^00 feet in depth. People within tn« City
of Galena receive armictng water from the balena puOhe water supply system,
*nicn provides good quality water from a deep aquifer, approximately
i,Ouu to l,2uti feet m depth.
Tne ualena subsite is cnaracterized by surface nine waste features :ia:
impact tne quality of tne shallow ground water aquifer. Tne most significant
mine waste area is referred to as "Hell's Half Acre," whicn contains sparse
to no vegetation and is totally covered witn surface mine wastes. The mines
areas contain over 350 open shafts and collapses wnicn are direct conauits iz
tne shallow ground water. Short Creeit flows through Hell's Half Acre. Utr.er
creeks in the area are Snoal CreeK and Owl Branch. Short and Shoal Creeps emp:/
into tne Spring tfiver, wnicn also flows througn the suosite.
SITE H1ST0HY
Ore was first discovered In the Tr1-State Mining District in 1848. Tne
first economically significant mine tn Kansas was tn the City of Galena, wnere
ore was discovered in 1876. Sphalerite (line sulfide) and galena (lead
sulfide} were the important cowmerdal ore minerals. Pyrlte and marcasue
(both iron disulfide) were commonly found In association with the lead and
zinc minerals. The district was an important source of cadmium, wnicn was
produced as a byproduct of the lead-zinc smelting process. A smelter was
built along Short Creek 1n tne 189U's. The area near tne original smelter
was used for various smelting facilities until around 1961, then the remaining
facility was converted to produce sulfuric acid.
Ore deposits in the (ialena vicinity occur In veins and are typically
80 to 1U0 reet deep. This shallow depth allowed numerous small mining
operations to prosper. Exploration and mine development were accomplished
by excavating vertical shafts to locate tne ore body. Mining progressed
outward from the vertical snafts using a modified room and pillar method to
follow tne ore vein. The use of vertical shafts as a means of mineral
exploration and tne suod1v1s1on of leases into small subleased mining plots
result in a nlgft density of mine snafts 1n the suosite. Over J50 open shafts
are readily accessible In and around tne City of Galena. Several mines have
collapsed, forming subsidences of varying sizes and shapes. Many circular
subsidences are less than 75 feet In diameter while others, from circular to
rectangular, measure several hundred feet along the longest dimension. A
ground level difference of 20 to AO feet 1s connon tn tne subsidences witnin
the suosite. Some subsidences are filled with water and may be deeper.
The most obvious remains of tne Intense mining activity at the subsite
are large areas covered by nine and mill wastes, water-filled subsidence
craters and open mine shafts. Tne localized term "chat" describes the waste
piles of gravel-sized rock, wnicn resulted from the early ore milling process.

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ui
\« (.HALF ACRE
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. r// . ,u\ m
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m
MINI WASUS
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FIGURE 7
GALENA SUBSITE
I MIIIIIHll COUNIT KAMV
I.A| | NA Stmsnt OlJt*
(•HIMMOMAIIIVVJiUAll »

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4
i-arge clunks of unmilled waste rock derived from the excavation of vertical
snafts nave Seen termed "Dullrocx." Little to no vegetation Is founa on
cnat-covered areas. Although a very large portion of the subsite is covered
Oy tnese en at ana Dull rock piles, it nas been impractical to measure or
estimate tne quantity of tms material at the site.
Tne £?A began its investigation of the Galena subsite in 1^85. A 'rtase
I remedial investigation was completed in 1*86. This investigation examined
t.ne impacts of tne mining activities on the ground water, surface water,
ambient air, soils, stream sediments and fisn. At the result of tms «ork,
determined additional information on the ground weter and surface water
was necessary In order to evaluate potential remedial actions. These additional
investigations were conducted in 1*86 and 1987.
The suoslte investigations 3mon*trated that the shallow ground water
acjifer ana tne surface water a-? contaminated wltn elevated concentrations of
metals. The private shallow a"fer wells that were found to be contaminated
nave oeen of great concern. Many o these private veils are contaminated
with metals tnat exceed the primary and secondary aaxlmia contaminant levels
estaohshed by the Safe Drinking water Act. Due to the concern for tne
health of persons drinking this contaminated water, EPA, Region VII conducted
a removal action and installed water treatment units on these wells with
permission of the property owners. Tnls removal action has been considered a
temporary protective measure.
Table 1 lists the average and maxima levels of metals observed in
private wells in the subslte and the drinking water standards. The metals of
most concern for human health are cadolua, lead, selenlua and zinc. The kidney
is the critical target organ In humans chronically exposed to cadmium by
ingestion. Exposure to lead can cause severe neurotoplc effects tnat include
irreversible brain damage. Selenlua ingestion causes depression, gastrointestinal
disturbances and occasional dermatitis. Excessive levels of zinc can cause
stomacn disorders. Exposure to cadalum can cause changes 1n the distribution
of zinc, with increases m the liver and kidneys.
ENFORCEMENT
General notice letters were Issued to Inform potentially responsible parties
(PRPs) of their potential liabilities for past activities at tne Cherokee County
site. Nine mining or former Mining companies were notified In 198S. Two
additional companies were notified of potential responsibility In 1986. The
original nine companies received notification prior to the removal action and

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laaatrat offtita
Haa tlnafi
4MMMI. tllltlnf
lattiutiaaal
contrail an
paaiic aatar
WMlf VitH tra
laiaMti. la*
flaniilltf far
aaalf/
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23
rameaial action, :ne acceptance criterion requires a review of tne state's
ability to provide tne required funds.
Tne comments received indicate tnat trie public would not accept tne
nonaction alternative. Many residents understand tne potential health nsxs
associated with arming contaminated water and also are concerned aoou: :ie
metals presenting taste, odor and color problems.
It is anticipated tnat the citizens benefiting from the remedial action
will be responsible for tne 10 percent funds and tne long-term Q4M of tne ac:-3-.
It was anticipated based on discussions witn KOHE tnat any alternative wit.i
nign 04M costs would not be supported by tne community. Alternative 2 has
tne lowest capital costs otner than tne nonaction alternative and also nas
tne nignest Otfi cost. Therefore, it is expected to be opposed by tne public
as a long-term solution. Public acceptance of Alternatives 3, 4 and 6 was
expected to be nigh because tnese alternatives provide a reliable supply of
good quality water.
It was expected that the public may be wary of accepting the treated
shallow ground water that would be provided 1n Alternative S. Also, nandllng
and disposing of wastes from the shallow ground water treatment may be generally
unacceptable to the public, especially those located near transportation
routes and the disposal site.
SELECTED REMEDY
General Description
Alternative 3 1s the selected remedial action for provision of an alternative
water supply for residents utilizing private water wells, wMcn currently
supply water from the contaminated shallow ground water aquifer. Alternative
3 utilizes the City of Selena's deep aquifer wells, wnlch supply reliable
good quality water. Distribution of the water will be accomplisned tnrougn a
pipeline network to be constructed that will reach all homes, farms and
businesses 1n the subslte.
The City of Galena's existing wells numbers one and two will be rehabilitated
to provide additional capacity for tne expanded system. The rehabilitation
wor* includes: 1) Replacement of upper well casing, 2) Replacement of pumps
for nigner pumping capacity, 3) Upgrading the wellhead facilities and *) Addition
of cnlorlnatlon facilities. If rehabilitation becomes infeaslble due to
unforeseen onslte technicalities, a new deep aquifer well may be drilled to
provide additional water. Existing pipelines within the current municipal
distribution system may be repaired or upgraded to facilitate additional flow
capacity.

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24
A new Hipeline network will be constructed to supply the additional
service areas, wnicn include trie west, Lowell, Nortn and Soutn service areas
as snown on Figure 2. Eacn of tne estimated 418 houses, Dusinesses and fams
in tnese areas will De connected to the water distribution system. Flow
val/es will oe installed for eacn residence and business and at the Galena
distribution area boundaries. A water storage tank will oe installed in
tne west service area. The existing wells will be disconnected from tne
nouses and businesses. If agreeable to tne property owners, tne wells will
be plugged.
The selected remedy includes the purchase and construction of all
equipment and facilities needed to operate and maintain tne alternative
water system collection, treatment and distribution.
Tne wells, cnlormatlon system and distribution within tne City of
uaiena will be ooerated and maintained by the City of (Selena. The water
distribution system outside of the City of Galena will be operated by an
entity to be selected by the citizens In the service areas outside of Galena.
Tnis entity may be tne City of Galena, a newly formed rural water district
or an expanded existing rural water district.
Scope and Function of Operable Unit
The Alternative Water Supply Operable Unit 1n the Galena subslte 1s
tne first of several operable units on the Cherokee County site. CERCIA
Section 118, as amended by SARA, requires the EPA to give h1gn priority to
response actions involving the release of hazardous substances into the
environment tnat resulted 1n the closing of drinking water wells or has
contaminated a principal drinking water supply. Therefore, the alternative
water supply operable unit has been conducted prior to other operable units
for tne Cherokee County site.
Tne purpose of this operable unit 1s to provide suitable drinking water
to the current population within the subslte. Suitable drinking water is
water that meets the primary MCls. Residences and businesses within the City
of Galena obtain their water from the public water supply, wnlcn already
provides suitable water. The population outside of Galena obtain their
water supply froa the shallow aquifer and are at risk of using water exceeding
tne MCls. A second goal of the remedial action 1s to protect the deep
aquifer from contamination that may occur as a result of Implementing an
alternative water supply.
A second operable unit 1n the Galena subslte will address the remediation
of tne contaminated ground water and surface water. The otner subsltes will
oe addressed as separate operable units.

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26
Performance tioals
Since the selected remedial action will operate as a public water supply,
tne water nust meet tne primary MCls as established by tne Safe Ormxing
aater Act. Tne water will be obtained from tne Roubldoux aquifer ana will
need no treatment otner tnan cnlonnatlon. The goals of tne action will ae
met as soon as the system is constructed ana on-line, i.e., tne action is
protective immediately upon implementation. All ARARs for tne remeaial act:on
will be obtainable. The ARARs are listed on Table 5.
Rationale for Preference
Tne selected remedial action Is preferred over all other alternatives
because it is the lowest cost alternative that provides the greatest protecf.on
to the public health. Water collected from the Roubldoux aquifer is of gooa
quality and meets the primary MCLs. Therefore, treatment 1s unnecessary,
which manes the selected alternative more effective and Implementable tnan
Alternatives 5 and 6. Alternative 2 may be a protective remedy, but due to
potential interrupted service, It Is not be as effective or Implementable as
tne selected remedial action. Alternative 3, the selected remedial action,
is superior to Alternative 4, which may be just as protective and effective,
because of administrative considerations. The City of Galena is a well
established entity and is very capable of maintaining a good supply of water.
The selected action utilizes the City's experience in supplying water, mile
Alternative 4 does not take advantage of this experience.
Tne costs of tne selected remedial action are lower than Alternatives 5
and 6 and are approximately the same as Alternative 4. Alternative 2
has a lower present worth, although the annual 04M 1s unacceptably nigner.
All alternatives except no action meet ARARs, so this was not a detenunng
factor. Although Alternatives S and 6 may reduce the mobility, toxicity and
volume of the contaminants, sucn reductions were not a goal for this operable
unit, but will be important in the second operable unit. The short-term
effectiveness of the selected remedial action and Alternatives 4, 5 and 6 is
comparable. Since there Is no construction 1n Alternative 2, Its short-term
effectiveness may be higher. The selected remedial action as well as Alternatives
4, 5 and 6 provide a permanent solution for an alternative water supply.

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Cherokee County • Galena Subsite
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Record of Decision for the Cherokee County Superfund Site -
Ground-water/Surface-water Operable Unit; EPA Region VII;
September 18, 1989

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CHEROKEE COUNTY
GALENA SUBSITE
RECORD OP DECISION
GROUND WATER/SURFACE WATER
OPERABLE UNIT
SEPTEMBER 18, 1989

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4
The second OUFS pertains to the ground water/surface water
remedial action. This study consists of two parts, the 1988 OUFS
and 19S9 OUFS Supplement, hereinafter referred to as the OUFS,
unless referenced otherwise. The RI and OUFS conclude that there
is a public health risk at the site due to ingestion of shallow
ground water and mine wastes. A risk at the site to the
environment also exists due to metals contamination in the
surface water. In addition, the OUFS screened and evaluated
remedial action alternatives that would affect ground water and
surface water contamination and remediate surface mine wastes.
Surface mine wastes, left onsite as the result of the mining
activities, are located throughout the subsite. Levels of lead
and cadmium in the surface mine wastes exceed the acceptable
intake levels through ingestion established by EPA reference
doses (RfO) and acceptable intake for chronic exposure (AIC), as
demonstrated in the OUFS. The mine wastes are readily accessible
to human exposure as many mine waste piles are adjacent to homes
and businesses in the subsite. Also, these areas of
contamination are commonly used for recreational areas for off-
road vehicles.
Surface waters in the subsite contain metals exceeding the
ambient water quality criteria for the protection of aquatic life
established by the Clean Water Act, as demonstrated in the RI and
OUFS. Such levels of contamination inhibit the growth and
development of aquatic life present within the waters of the
subsite. The impact of the contamination is particularly evident
in Short Creek which has little to no aquatic life.
The decision to implement the remedial action is based on
the actual and threatened release of hazardous substances into
the shallow ground water and surface water and the threat of
direct human exposure to the contaminants in the surface mine
waste piles and subsequent ingestion of the contaminants. These
releases and threats are primarily the result of mining
activities conducted at the subsite and weathering and oxidation
of the mining wastes.
2.0 SUE LOCATION ABB description
The Cherokee County site is the Kansas portion of the Tri-
State Mining District, which includes the lead and zinc mining
areas in Jasper County, Missouri, Cherokee County, Kansas, and
Ottawa County, Oklahoma. Cherokee County is located in the
extreme southeastern corner of Kansas. As shown on Figure 1, the
Galena subsite is one of six subsites identified within the
Cherokee County site and encompasses approximately 25 square
miles. A more detailed map of the Galena subsite including mine
waste study zones is presented in Figure 2.

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5
The Galena subsite is characterized by surface nine act*
features that directly impact the quality of the shallow ground
water aquifer and the surface water. The Bine waste areas
contain sparse to no vegetation. Approximately 900 acres have
been disturbed by the mining activities and are partially covered
with surface sine wastes. The ained areas contain approximately
3,000 shafts including 580 open shafts and surface collapses,
many of which are direct conduits to the shallow ground water.
Short Creek and Owl Branch flow through the mined areas in the
subsite. Shoal Creek receives runoff from the mined lands. Short
Creek and Shoal Creek empty into the Spring River, which flows
through the subsite and into Oklahoma.
The City of Galena, population approximately 3,500, is
surrounded by the mine waste areas. Many houses are immediately
adjacent to the mine waste piles. Approximately 1,050 additional
people live within the subsite but outside of the city limits.
The land in this rural area is primarily used for livestock
grazing and crop production.
3.0 SITE HISTORY
Ore was first discovered in the Tri-State Mining District in
1848. The first economically significant mine in Kansas was in
the City of Galena, where ore was discovered in 1876. Sphalerite
(zinc sulfide) and galena (lead sulfide) were the important
commercial ore minerals. The district was an important source
of cadmium, whieh was produced as a by-product of the lead-zinc
smelting process. Pyrite and marcasite (both iron disulfide)
made up about five percent of the minerals in the Galena area. A
smelter was built along Short Creek in the 1890's. The area near
the original smelter was used for various smelting facilities
until around 1961.
ore deposits in the Galena vieinity occur from near surface
to depths of 100 feet. This shallow depth allowed numerous small
mining operations to prosper. Exploration and mine development
were accomplished by excavating vertical shafts to locate the ore
body. Mining progressed outward from the vertical shafts using a
modified rooa and pillar method to follow the ore vein. The use
of vertical shafts as a means of mineral exploration and the
subdivision of leases into small mining plots resulted in a high
density of mine shafts in the subsite. Several mines have
collapsed, forming subsidences of varying sixes and shapes. Many
circular subsidences are less than 75 feet in diameter while
others, from circular to rectangular, measure several hundred
feet along the longest dimension. A ground level difference of
20 to 40 feet is eomaon in the subsidences within the subsite.
Some subsidences are filled with water and may be deeper.

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6
The Bost obvious reaaina of tha intense mining activity at
the subsite are larga areas covarad by aine wastes, water-filled
subsidence cratara and opan aina shafts. The surfaca aina wastes
include bullrock, dtiap aatarial and chat. Bullrock and duap
aatarial consist of aostly coarsa aatarial and unaconoaie ora
reaovad from shafts and aina workings during axcavation and aina
davalopaant. Tha unprocassad bullrock and duap aatarial raaain
naar aany of tha opan pits, shafts and subsidancas. Bullrock and
duap aatarial will b« rafarrad to as wasta rock harainaftar.
Chat consists of fine-grained aatarial that has baan processed
(aillad) to raaova tha aatal aulfida ainarals. Little to no
vegetation is found on the areas covered by the aine wastes.
The EPA began its investigation of the Calena subsits in
1965. A Phase I raaadial investigation was eoapleted in 1966.
This investigation exaained the effects of the aining activities
on tha ground water, surfaca water, ambient air, soils, stream
sediments and fish. As the result of this work, EPA determined
additional information on the ground water and surfaca water was
necessary in orde:Tto evaluate potential remedial actions. These
additional reaedial investigations were conducted in 1966 and
1987. in 1988, EPA continued its investigation of the mine waste
materials and developed a proposal for remediating the Galena
subsite.
Tha subsite investigations deaonstratad that tha shallow
ground water aquifer and tha surfaca water in the subsite are
contaminated with elevated concentrations of aetals. Many
private shallow aquifar walls are contaminated with aetals that
exceed the priaary and secondary MCLs established by tha Safa
Drinking Water Act. Due to the concern for the health of persons
drinking this contaainatad water, EPA Region vxi installed water
treataent units on savaral walls as a taaporary protective
measure. These hoaas will ba connected to tha Cherokee County
RWD No. 8 in tha naar future, within approxiaately two years.
In February 1988, tha EPA ralaasad for public coanent, a
Proposed Plan to address tha ground water and surfaca water
contaaination in tha Calena subsite. As stated in tha 1988
Proposed Flan, tha prafarrad raaadial alternative consisted of
four coaponants: 1) removing (aining), Billing and processing
(flotation) of tha surfaca aina vastas; 2) channeling salact
straaas and drainage areas; 3) recontouring tha ground aurfaca;
and 4) investigating and reaadiating aubaita deep walls. In
response to eoaaanta raeaivad during tha public coaaant period
and to satisfy tha n«ad for additional information,
investigations vara subsequently conductad. These investigations
detarainad that tha Billing and flotation coaponent of tha 1988
preferred reaady vaa not as iapleaentable and aconoaical as
originally astlaatad. Tha raaedy chosen in this ROD replaces the
Billing and processing coaponent of tha 1986 prafarrad remedial

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8
Plan was open for 54 days. A public meeting was held in Galena
on August 3, 1989, to discuss the 1989 Proposed Plan and OUFS
Supplement. A public comment period on the OUFS Supplement and
1989 Proposed Plan vas open for 34 days. A responsiveness
summary of public comments received during both the 1988 and
1989 public comment periods is part of this Record of Decision.
Information regarding EPA's activities at the site has been
available at the Galena Public Library which has been used as an
information repository and is the location for the administrative
record. All community relations activities have been in
conformance with the requirements of Sections 117 and 113(k) of
CERCLA, 42 U.S.C. Sections 9617 and 9613(k), and to the extent
practicable, the National Contingency Plan (NCP) 40 CFR Part 300
(1980).
A task force, formed to assist coordination of 6tate and
federal activities in Cherokee County, Kansas, continues to hold
periodic meetings in Galena. This task force is comprised of
representatives from the local community and state and federal
agencies.
6.0 SCOPE AND ROLE QZ OPERABLE UNIT
The ground vater/surface water operable unit is the second
of two operable units for the Galena subsite. The first operable
unit addresses the alternative water supply for the residents who
are dependent on the shallow aquifer for drinking water. These
two operable units address the public health and environmental
threats at the Galena subsite. Additional remedial
investigation/feasibility study (RI/FS) and remedial
design/remedial action (RD/RA) activities will be conducted at
the other subsites as operable units.
7.0 SITE CHARACTERISTICS AND SITE RISKS
The site investigations and the OUFS for the ground water
and surface water remediation demonstrate that the primary health
risk at the Galena subsite is the ingestion of the shallow ground
water and the ingestion of surface mine wastes. Environmental
risks include the contamination of the surface waters with metals
at levels exceeding Federal and State ambient water quality
criteria and standards. These exceedances are of particular
concern in Shoal Creek because the creek has been designated a
habitat for one or more Kansas designated endangered species.
The RI and OUFS show that the surface mine waste piles, mine
wastes remaining underground and unmined minerals in the bedrock
are the sources of the contamination in the ground water and
surface water. The availability of the sulfide minerals in the
mine workings and dissolved oxygen in the ground water result in
the production of sulfuric acid followed by dissolution of metal

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9
sulfides. A similar action occurs on the surface with tha
ainerals in tha vasta pilaa reacting with oxygenated rain and
snow malt. Tha acidic aetala-laden watar ia referred to as acid
aine drainage. Acid aina drainage from tha wasta piles, runoff
from tha wasta pilas and contaainatad ground watar discharge to
tha streaas, aach contributing to tha contamination of tha
surface watar.
Approxiaataly 510 housaholds outsida of tha City of Galsna
depsnd on privata walla in tha ahallow ground watar aquifsr for
thair drinking watar. Thaaa walla ara obtaining watar froa tha
saaa gaologle formation that had praviously baan ainad. Tha RI
and OUFS show that tha watar froa savaral of tha privata walls
contains cadmium, chromium, lead, nickel and salaniua exceeding
tha health-baaed drinking watar standards. Tabla 1 lists tha
avaraga and maximum levels of aatals obsarvsd in privata watar
wells during tha RZ for tha aubaita coaparad to tha drinking
watar standards.
Exposure to tha metals found in tha privata wells may causa
harm to human haalth. Cadaiua and chroaiua ingestion may causa
kidnay daaaga with chroaiua also potantially adversely affecting
tha liver. Ingastion of laad Bay causa narvous systaa and
irreversible brain daaaga particularly in children. Nickel
ingastion Bay affact body weight while ingestion of selenium can
causa dapraasion and gastrointastinal disturbances.
The RI and OUFS show that tha mina wastas and soils contaminated
with mina wastaa also praaant a human haalth risk as a result of
incidental ingaation of tha material. As aavaral of tha waste
araas ara in closa proximity to rasidantial araas, exposures can
occur in a raaidantial setting by childran and adults ingesting
soil or vegetables incidentally through normal everyday
activities, (i.e., playing or working in the yard, gardening and
other similar activitiea). Exposures can also occur through
breathing and inhalation of dust generated by such activities.
The surface mine waste have been sources of gravel and fill
material used on residential properties. Children and adults
also are expoaed to the metals in the mine wastes through
recreational use of the Bine waste areas. The mine waata araas
are used for dirt bike and other off-road vehicle activities.
Table 2 lists the maximum metal concentrations observed in
surfaea soils and mine wastas.
Reference doses (RfDs) and acceptable intakes for chronic
exposures (AICs) have been developed by EPA for indicating tha
potential for adverse health effects from exposure to chemicals
exhibiting noncarcinogenie effects. RfDs and AICs are estimates
of an exposure level that would not be expected to cauaa adverse
effects when exposures occur for a significant portion of a
lifespan. RfDs, which are expressed in units of mg/kg-day, are
estimates of lifetime daily exposure levels for humans, including

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TABLE 1
CONCENTRATIONS (ug/l)a OF TOTAL METALS
OBSERVED IN PRIVATE WELLS
Average	maxIbub	Criteria
Barium
83.5
390
Cadmium
5.6
180
Chromium
6.8
120
Copper
14.5
140
Lead
25.5
230
Manganese
92
3,400
Mercury
0.14
0
Nickel
23
270
Selenium
3.8
24
Silver
6.9
11
Zinc
841
15,000
l,oooj
10b
50" (total)
l,000®d
50
50c
15o£
10b
50*
5,000c
a « Micrograms per liter or parts per billion
b « Primary Maximum Contaminant Level (MCL), Safe Drinking Water Act
c - Secondary MCL, Safe Drinking Water Act
d «= The proposed secondary MCL for copper is 1,300 ug/1
e = The proposed MCL for lead is 5 ug/1
f'= Lifetime Health Advisory (EPA, Office of Drinking Water)


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10
sensitive individuals. Estiaated intakes of cheaicals froa
environmental media (e.g.» th« aaeunt of a chemical ingested from
contaminated drinking water or soil) can ba coaparad to tha RfD.
RfDs arc darivad froa huaan epidemiological studias or aniaal
studies to which uncertainty faetors hava baan appliad (a.g.,
uncartainty factors aaong othar things, account for tha usa of
aniaal data to pradict affacts on huaans). Thasa uncartainty
factors halp ansura that tha RfDs vill not undarastiaata tha
potential for adverse noncarcinogenic effects to occur. Tables 3
and 4 show the coaparison of aaxiaua daily Intakes to RfDs and
AICs for soil and aine waste ingestion. Lead and cadaiua are the
aatals of aost concern due to incidental ingestion. Ingestion of
the aino wastes represents the aost significant exposure pathway
for children, who aore frequently than adults play in dusty areas
and thus incidentally ingest that dust.
Analysis of saaples taken froa tributaries to Shoal creek
have shown concentrations of lead, zinc and cadaiua exceeding
both acute and chronic exposure criteria for aquatic life. Shoal
Creek is of special concern with respect to potential
environmental effects because natural caves near Shoal Creek
provide a critical habitat for one or more species of salamanders
listed as endangered by the State of Kansas.
Both the acute and chronic exposure levels for aquatic life
for cadaiua and zine are exceeded in Short Creek and its
tributarires. The chronic exposure level for lead is also
axcaeded in Short Creek.
The Spring River is iapacted by aining activities in both
Hissouri and Kansas, within the Galena subsita, both Short Creek
and Shoal Creek discharge into the Spring River. The chronic
exposure level for aquatie life for zinc is exceeded in the
Spring River within the Galena subsite.
The public health related standards and environaental
standards as coapared to the nuaber qf exceedances for saaple
stations on Short Creek, Shoal Creek and Spring River are
presented and discussed in detail in the RZ report and 1988 OUFS.
8.0 POST 1988 OCT3 STtTPTES
In February 1988 EPA raleesed a first Proposed Plan,
describing tha preferred reaedy for the Ground Hater/Surface
water Operable Unit. This Proposed Plan discussed five of the
alternatives evaluated in the 1988 OUTS. The 1988 preferred
reaedy called for reaoval, Billing and processing of surface aine
wastes, recontouring the ground surfsee, rechanneling selected
streaas and drainage areas and inveetigating and reaediating as
necessary, deep aquifer veils. Consents received during the
public cooaent period and the need for additional design
inforaotion proaoted efforts to further study reaedial

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11
alternatives.
8.1 EPA Studies
In May 1988, the EPA initiated studies to determine process
treatment parameters to mill and process the mine wastes. A more
detailed understanding of specific process variables was also
needed to respond to significant comments received during the
public comment period on the 1988 preferred remedy. The primary
objectives of the additional work were to collect samples of
high- and low-grade mine wastes and then conduct metallurgical
tests on these materials to better define design and operating
parameters for the treatment process proposed.
Results of onsite characterization activities indicated that
waste rock piles have a wide size distribution of materials with
corresponding highly variable metals concentrations. A portable
X-ray fluorescence (XRF) spectrometer used to semi-quantitatively
identify lead and zinc concentrations of mine waste samples,
indicated that many chat piles contained substantial lead and
zinc concentrations. Wet screening and further chemical analyses
on the chat samples showed that most of the lead was in the very
fine-sized fraction of the chat. This fine-sized fraction
includes the materials most likely to be ingested.
The results of the metallurgical tests revealed that the
milling/flotation process required for sufficient metal
(primarily lead, zinc, and cadmium) recoveries from both the
waste rock and the chat would be far more complex than originally
envisioned. For example, the waste rock was harder than
expected, so the crushing and grinding circuits would be larger
and more expensive to build and operate. In addition, these
tests determined that the quantities of metal oxide forms present
in both waste rock and chat would have to be recovered as well as
the sulfides to produce satisfactory metals removal and an
acceptable tailing. As a result, further tests and studies on
the mine wastes were conducted and the Agency developed the 1989
OUFS Supplement. This OUFS Supplement re-evaluates the 1988
preferred remedy and evaluates additional remedial alternatives
in light of the new information gathered subsequent to
publication of the 1988 preferred remedy.
8.2. £££ Studies
In addition to the studies and testing conducted by EPA, a
group of potentially responsible parties (PRPs) conducted field
investigations and leach tests. The PRP group conducted column
leach tests on waste rock, chat and a simulated mill process
tailing to better understand the geochemical behavior of these
wastes. The PRPs estimated volumes of the various mine wastes
within the subsites's eight EPA-defined waste zones. This work
indicated that there are about 550,000 cubic yards (yd3) of waste

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12
rock (including associated contaminated soils) and approximately
750,000 yd3 of chat. In addition, estimates of below-grade
surficial (open to the surface) void-space volumes (vith and
without a shallow-water table influence} were determined. This
work estimated that there is surficial void space of about 1.9
million yd3, including approximately 0.8 million yd3 holding
water and 1.1 million yd3 without water. These estimates of
surface mine wastes are much higher than the estimates presented
in the 1988 OUFS. The EPA has determined that the PRPs'
estimates are more accurate since they have been based on
detailed field reconnaissance. Analyses of mine waste rock and
chat samples indicated that metal concentrations vary widely in
the materials tested confirming previous EPA test results.
The PRP Group conducted onsite pilot leach tests, utilizing
local mine waste rock, chat and water. Various mine wastes and
waters from the subsite were subjected to several 24-hour batch
tests and three flow-through tests of extended duration
(approximately 8 days). Results of these tests support the EPA's
remedy selected herein.
9.0	DEVELOPMENT ££ ALTERNATIVES
The remedial alternatives for the ground water/surface water
operable unit were developed and evaluated in compliance with
CERCLA and the NCP. Section 121(b) of CERCLA, 42 U.S.C. Section
9621(b), provides that a remedy shall be selected that is
protective of human health and the environment, that is cost-
effective and that utilizes permanent solutions and alternative
treatment technologies or resource recovery technologies to the
maximum extent practicable. The OUFS for the ground water and
surface water remediation evaluates alternatives with respect to
the requirements of that section.
9.1	Remediation Goals
Remediation goals for the Galen* subsite include both long-
term and short-term goals. Table 5 identifies both the long-
term and short-term goals for the Galena subsite. Implementation
of the selected remedial action for this operable unit will
address both the short-term and promote achievement of the long-
term goals.
9.2	Remediation &£li£Q Levels
The potential hazards to public health were also further
evaluated subsequent to completion of the 1988 OUFS. The
principal contaminant of concern at the Cherokee County site is
lead. The Center for Disease Control (CDC) and, subsequently,
the Agency for Toxic Substance Disease Registry (ATSDR) have
historically supported using an action level for lead in soil of
1,000 mg/kg (ppm) or below. This action level has been based on

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13
studies which revealed elevated blood lead levels in children
living on sites that contained greater than 500 ppm lead. On a
case-by-case basis, the EPA has adopted a lead action level at
1,000 ppm or below for sites in a residential setting. Mine
wastes in the Galena subsite are located directly adjacent to a
number of residences and the community of Galena. The Agency has
thus considered the Galena subsite a residential setting and
adopted 1,000 ppm as the action level for lead at the subsite.
As a result of this determination, the selected remedy will
place mine wastes containing lead above 1,000 ppm below ground
and potentially use mine wastes containing less than 1,000 ppm
lead for cover material.
Land use restrictions will be established and maintained on
the deeds of the properties affected by the remedial action. The
State of Kansas or local government will establish these
restriction to prevent mining and excavation in the remediated
areas and to assure the integrity of the remedial action. These
controls, however, will not restrict activities related to
gardening, livestock grazing or residential exposures.
To assure that the health concerns related to cadmium are
addressed, the Agency has established a cadmium level of concern
at 25 ppm. Materials containing cadmium above 25 ppm will not be
used for cover and will rather be placed below ground. The
cadmium level of concern has been established based on
consideration that future land use may include gardening
(incidental and some subsistence use), livestock grazing or
residential uses. Cadmium in soil greater 'than 10 to 20 ppm at
other Superfund sites has been considered unacceptable for use in
gardens. In addition, toxic effects have been exhibited in
cattle grazing on vegetation containing 5 to 10 ppm cadmium.
Calculations relating to residential exposures have supported
less conservative levels of concern for cadmium at between 50 and
100 ppm. However, since restrictions on all types of land use
are not anticipated, the Agency has determined that an
appropriate level of concern for cadmium is 25 ppm.
In addition to lead and cadmium, a level of concern has been
established for zinc concentrations contained in the mine waste
chat due to its potential adverse effects to area biota and based
on zinc's tendency to leach from the mine waste and migrate in
ground water and surface water. The concentration of zinc in
chat will dictate what chat is placed potentially below the
ground water table. Based on results of the pilot leach tests,
which were conducted using a mixture of chat and waste rock and
local water having a pH greater than 5, chat containing the
following levels of zinc will be placed as described below. Chat
containing zinc above 10,000 mg/kg (ppm) will be placed in dry
mine voids. Chat containing zinc below 10,000 ppm may be placed
in either dry voids or voids containing water. The level of zinc
contained in the chat is not the determining factor for what

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19
surface water aetals loading. The first coaponent provides the
following:
Resove and transport all aine vasta rock and chat to a
single containment unit. Tha unit would be dasignad to aaat RCRA
design critaria for hazardous wasta.
Alternative £ - 1212 ££££ Supplement
The objective of Alternative 5 is to raaove the source
aaterials froa the surface and selectively plaee thea in aine
voids to essentially eliminate the risk posed by ingestion of
aetal contaminated wasta. Alternative 5 would be impleaented in
a aanncr that proaotas iaprovaaent of the shallow ground water
and surface water quality. Tha first coaponant provides the
following:
Raaove all aine waste rock and chat and selectively place
the aatarial in available pits, shafts and subsidences. Haste
rock would be placed below ground based on size. Chat would be
characterized as to lead and zinc content and placed below ground
or used for surface cover based on aetal content.
11.0 DEVELOPMENT AWD DETAILED EVALPATIOH OF THE SELECTED REMEDY
n.i pMgriBUgn
Alternative 5 - 19B9 OUTS Suppleaent is the selected remedy.
The four eoaponents of this alternative are described in detail
as follows:
The selected reaedy is to aine, characterize and selectively
place surface-deposited aine wastes (waste rock and chat) in open
subsidences, pits and shafts. This action will essentially
eliainata human exposure via ingestion to contaminated aine
wastes and reduce long-ten shallow ground water and surface
water aetals loading. The selected•reaedy includes diverting and
rechanneling certain surface drainages and recontouring and
vegetating the ground surface to the extent possible. These
actions will ainiaise recharge to the shallow ground water
systea, reduce infiltration through the cover aatarial, proaote
proper surface drainage and control erosion. The selected reaedy
requires investigation and raaediation, as necessary, of wells
penetrating the deep aquifer to protect against eontaaination
froa the shallow aquifer and aining-related activities.
11.2 Mining. Sernnlna PI»e«»«wt q£ Vmmtm Rock
within a given zone, waste reck will be reaoved, transferred
to a nearby portable screening plant and then dry screened at a
noainal two-inch size. Tests indicate that the minus two-inch
(finer) size fraction of waste rock will be highly reective with

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Table 7
SELECTED REMEDY
DETAILED COST SUMMARY
I. Actions to Support Mint Wast* Disposal	costs
A.	Reaove/Dispose Mine Wastes	$3,714,723
B.	Placeaent of Covsr Material	1,012,302
C.	Support Sits Work	236,351
D.	Mine Wastss Screening Plant
1.	Capital Costs	192,000
2.	Operating Costs	185,529
E.	Supporting Fiald Work
1.	Chat Characterization	393,400
2.	Cut/Fill Engineering	197,200
II. Recontour/Vegetation
568 acres at $1000/acre	568,000
III. Reehannelization	696,000
V. Deep Well Investigation/Reaediation	175,600
V. Water Quality Monitoring	170,000
PROJECT COSTS SUBTOTAL	7,541,105
Contingencies	754.110
8,295,215
OPERATION AND MAINTENANCE - ANNUAL
Cover Maintenance	10,123
Channel Maintenance	3.480
SUBTOTAL	13,603
Contingencies	1,360
14,963

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31
Response: The assessment of macroinvertebrate populations
in the Spring River was based on existing scientific literature
(KDHE 1980 and 1934? Branson 1966) since there were no site-
specific studies of benthic biota conducted. Data from the
macroinvertebrate studies were also compared to water quality
data in the literature and data collected during the remedial .
investigation.
The KDHE (1980) water quality and biological survey of the
Spring River and its tributarires noted low diversity and absence
of several pollution-sensitive benthic groups in the lower
reaches of the Spring River, and KDHE (1980) made the following
statements.
The biota in the lower reaches of the Spring River which
receives mine drainage from several polluted tributaries
continues to be stressed.
Heavy metals in solution constitute a very serious form
of pollution because they are very stable compounds not
readily removed by oxidation, precipitation or other
natural process. (This is especially true of zinc.)
*
The general depletion at the downstream stations is
attributed to continued exposure to lead-zinc mine
drainage.
It is postulated that zinc toxicity was probably
indirectly responsible for the restricted taxa due to
limited variety of food available.

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32
*	The drastic reduction in taxa, especially the mayflies,
is attributed to chronic exposure to heavy metals.
•	A similar biological depletion of the lead-zinc pollution
sensitive MCOL group was noted in the benthic samples
from Center Creek during 1964-65 pollution survey by
Missouri. (Biological Data - 1973. James, Elk and
Spring Basin Hater Quality Report. Missouri Clean Water
Commission, Jefferson City, Missouri. 1974.).pm
Scientific investigators will agree that there are several
water quality parameters (such as ammonia, nutrients, organics)
and physical factors (such as flow and substrate type) operating
on the benthic macroinvertebrate populations in the Spring River,
in addition to metals concentrations. Most would also agree that
increasing nutrients and organic pollution along the Spring River
probably cause some reduction of benthic diversity. However, the
nine-year plus biomonitoring data base on the Spring River
indicates a consistent reduction in benthic macroinvertebrates in
the Kansas portion of the river and a consistent and
corresponding increase in metals concentrations. Metal
concentrations almost certainly play a role in reduced benthic
diversity, especially since some metals are almost always above
concentrations known to have a chronic effect on aquatic biota.
34. £2imfiB£: The commenters state that the sources of
contaainants are not defined; therefore, the importance of the
different sources of biological stress to the waterways cannot be

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Cherokee County - Galena Subsite
Mining Waste NPL Site Summary Report
Reference 3
Excerpts From Ground-water and Surface-water Operable Unit Feasibility Study, Galena
Subsite, Cherokee County Site, Kansas • Final Draft; EPA Region VII;
February 26, 1988

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carbonates contain the shallow aquifer and are the host rocks
for the mined ore bodies. Because mining occurred in these
rock formations, the shallow wells are potentially subject
to contamination due to the abandoned mines and mine wastes.
The shallow aquifer is used by over 1,000 residents within
the Galena Subsite as their primary source of potable water
(private shallow wells). Cambrian-Ordovician strata, largely
dolomites and sandy dolomites, contain the deep confined
aquifer. This regional aquifer, frequently referred to as
the Roubidoux Aquifer, is used by many cities, rural water
districts, and industries in Kansas and Oklahoma.
In the Galena area, the potentially confining aquitard above
the deep aquifer is composed of up to 20 feet of discontin-
uous Mississippian shale lenses. South and west of Galena,
in Oklahoma, the Devonian aged Chattanooga Shale reportedly
forms a continuous aquitard. Therefore, the hydraulic separ-
ation between the shallow and deep aquifers within the Galena
Subsite has not been completely defined. Also, in some cases
these confining layers are breached by wells (some unused)
tapping the deep aquifer. Six deep wells of varying -ages
have been located in the subsite, and there may be more.
Several could be potential conduits for migration of contami-
nated shallow aquifer water into the deep aquifer.
SURFACE DRAINAGES
The surface water drainages in the subsite are shown in
Figure 2. The Galena Subsite drains to the Spring River,
Short Creek, Shoal Creek, and their tributaries. The major
drainage basin is the Short Creek watershed, which flows
east to west (from Missouri) through the northern portion of
the Galena Subsite. Most of the drainage into Short Creek
from the subsite is via Owl Branch and Tributary A (see
Figure 2).
DE/CC11/007
4

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LEGEND


boundary of

GALENA SUB5IIE
V/A
APPROXIMATE GALENA
t / / A
CltY ilMlf s
¦¦
MINE WASTES
m
MINE WASIE STUD*
i j
/ONES
FOR
NORTHERN PORTION
SEE FIGURE 1
~
" v\'
*""S STAT«oi V
' I 4 HELL S
' \. 1 HALF ACRE -r
w»e^n . .¦*	v i?i,r.
n
l f "4»
J"t |
\ • ? 'vr- .
imm j ¦ K I	•
i	j	i j	 c
r / ' :~r VT^r
>-J ^:o('-.iW3i
1
*li	i^jrT	. vjk
iV' _ ftvV V
\ • '»
'• ^
-H); =
re !3-/
SCA|( in MIUS
¦-w . VjiV" y^^r(rt *v
—' v <¦- •'¦ V fiK ' •1
r :Wrr
FIGURE 2
GALENA SUBSITE
iv I ' CHEnOKEE COUNTY. KANSAS
|	GAICNA SUBSITE

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Mining activities changed the hydrology of the area by creat-
ing underground voids, causing subsidences, and leaving mine
wastes on the surface. These actions disrupted the normal
surface drainage and depleted the vegetation, thereby enhanc-
ing infiltration of surface water into the groundwater system.
In some cases, the entire flow in a surface stream, such as
Tributary A along Hell's Half Acre (see Figure 2), is captured
by a subsidence or shaft, directing it into the shallow aquifer.
Over much of the area covered by mine wastes nearly all of
the rain infiltrates into the ground because of its highly
permeable condition and the closed surface drainages. The
shallow groundwater, in turn, flows (as nonpoint discharges)
into the major creeks such as Short Creek, maintaining their
year-around base flows. The interconnected shallow mine
workings provide a conduit that greatly enhances lateral
groundwater movement.
MINE WASTES
Mine wastes resulting from shaft excavation, ore milling
processes, and smelter operations have been disposed of on
the ground near mine shafts and mill sites. These mine
wastes cover about 8 percent of the area within the Galena
Subsite (see Figure 2) and contain residual sulfide minerals,
plus the oxide, carbonate, and sulfate minerals resulting
from weathering of the sulfide minerals. The underground
mine workings also contain minerals left in pillars, at the
periphery of the mined zones, and in mine wastes left under-
ground. Water moves through the surface mine wastes and
underground workings and in an oxidizing environment reacts
with the sulfide minerals to form acid. The acidic solution,
in turn, dissolves metals in the minerals and results in
AMD. The metals, including lead, zinc, and cadmium, are then
transported from the source by the surface and groundwater
systems. Much of the AMD eventually goes into the Spring
DE/CC11/007
6

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o Influent groundwater sources in the Short Creek,
Tributary A (or Hell's Half Acre), and Owl Branch
drainages unrelated to the subsite mining activity
(i.e., areas in the upper portions of these
watersheds, including Missouri).
o Areas of surface mine wastes in Hell's Half Acre,
the Owl Branch drainage, and along Short Creek.
o Areas of underground remnant mineralization in the
vicinity of the mine workings in Hel-l's Half Acre,
the Owl Branch drainage (including the Blue Hole
area), and along Short Creek.
The hydrologic model was used to estimate the quantities of
two metals (zinc and cadmium) and sulfate flowing through
the surface water and groundwater systems. Zinc and cadmium
are mobile metals in the systems and are derived primarily
from the mine wastes and underground mineralization. They
are transported conservatively through the surface and
groundwater systems. That is, these metals tend to remain
in solution once dissolved and do not precipitate out with
minor changes in pH, temperature, or hardness. The same is
true for the sulfate ion. These metals, therefore, were
used as surrogates to depict transport of metal ions through
the water systems.
Despite the existence of high concentrations of lead in mine
wastes at the subsite, lead was not used in the modeling
because it tends to precipitate out of solution with minor
changes in the transporting media (such as pH).
Figure 4 depicts the sources of contamination and their rela-
tive contributions to the Short Creek basin. Most of the
drainage to Short Creek from the mined lands occurs between
DE/CC11/007
11

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Station 2 near the Kansas-Missouri state line and Station 4
about 1 mile above Spring River. The surface mine wastes
contribute about 26 percent of the total cadmium and zinc
loads while the underground mine workings and associated
mineralization contribute approximately 67 percent of the
zinc and 74 percent of the cadmium mass loads. The large
groundwater contribution is attributed largely to the high
volume of oxygenated water that infiltrates through the
porous mine wastes into the mine workings and the ground-
water system, and to the relatively rapid lateral flow rate
within the shallow aquifer that results from the underground
mine voids and the mining-induced fractures.
The conceptual model analysis showed that upstream surface
water and groundwater contributions to the zinc and cadmium
mass loadings in Short Creek are very minor compared to waters
from the mined areas, with the exception that 7 percent of
the zinc load comes from the Short Creek watershed in Missouri
(see Figure 4).
IMPACT OF CONTAMINANTS
GROUNDWATER SYSTEM
EPA has sampled 123 shallow aquifer wells in the Galena Sub-
site since 1985. In addition, groundwater from eight mine
shafts was also sampled. Location of these wells and mine
shafts and results of the chemical analyses are shown in
Figure 5. The water quality in the mine shafts was
generally more degraded than that found in shallow wells.
Sampling results showed that about 10 percent of the total
wells sampled exceeded one or more primary drinking water
standards (maximum contaminant levels—MCL*s). In addition,
DE/CC11/007
12

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Section 3
PUBLIC HEALTH AND ENVIRONMENTAL
RISK ASSESSMENT
This risk assessment addresses the potential hazards to pub-
lic health and the environment associated with the Galena
Subsite as it currently exists and under the no action alter-
native. Evaluation of the no action alternative is required
under Section 300.68(f)(v) of the National Contingency Plan
(NCP). The no action alternative assumes that no remedial
actions take place and no restrictions are placed on future
uses of the site.
PUBLIC HEALTH ASSESSMENT
INTRODUCTION
This risk assessment focuses on metals of greatest concern
based on toxicity, mobility, persistence, and concentration.
Metals of concern and their mobility in the existing environ-
mental setting have been identified in Section 2, Site Charac-
terization. This is followed by exposure assessment, which
identifies potential exposure pathways for plausible exposure
settings and presents concentrations of contaminants at
points of exposure. Potential intakes of contaminants are
estimated for each exposure pathway.
Next, toxicity is assessed by summarizing toxicity profiles
and presenting critical toxicity values for metals of
concern.
Finally, toxicity and exposure assessments are integrated to
estimate the potential risk to public health and the environ-
ment from exposure to metals of concern.
DE/CC11/014
3-1

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EXPOSURE ASSESSMENT
The purpose of this exposure assessment at the Galena Sub-
site is to "evaluate all existing exposure routes and those
which may reasonably be anticipated to exist in the future"
(EPA, 1986c) as it pertains to the groundwater and surface
water contamination. This assessment includes exposure
contaminated groundwater, surface water, and surface solids
(mine waste and contaminated soils) at the Galena Subsite.
It is based on the data obtained during the Phase I RI (EPA,
1986a) and subsequent sampling efforts, summarized in the
previous section on site characterization. Exposure path-
ways that are quantitatively assessed are summarized in
Table 3-1. In addition, exposure resulting from recreational
use of contaminated areas is discussed qualitatively.
Media
Groundwater
Surface Water
Surface Solids
Fish
Table 3-1
EXPOSURE PATHWAYS
INCLUDED IN THE ASSESSMENT
	Exposure Pathway	
Ingestion of contaminated drinking water
Incidental ingestion during recreational
use (swimming)
Dermal absorption during recreational use
(swimming)
Incidental ingestion
Ingestion of fish from contaminated sur-
face waters
Other potential pathways of exposure were considered but
were neither quantitatively nor qualitatively addressed.
These included dermal absorption of metals through direct
contact with contaminated soils, inhalation of metals during
DE/CCll/014
3-2

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swimming and showering in contaminated water, and ingestion
of contaminated food crops. It was assumed that the first
two pathways would represent small exposures as compared to
the pathways that were quantitatively addressed. Exposures
resulting from ingestion of contaminated food crops were not
assessed because of a lack of data on contaminant concen-
trations in crops and crop production in the subsite area.
Finally, as this OUFS specifically addresses surface water
and groundwater contamination, potential exposures resulting
from inhalation of contaminated particulates in the ambient
air were excluded.
Land use in the Galena Subsite includes residential, commer-
cial, light industrial, rural residential, agricultural crop
land, pasture land, scattered deciduous woodland, and aban-
doned mine land (EPA, 1986a). Demographically, the popula-
tion within the City of Galena has not changed significantly
over the last 25 years. In 1985, the population of the city
was estimated to be 3,616 (EPA, 1986a). For the purposes of
this Public Health Assessment, it is assumed that the land
use and demographics at the Galena Subsite will remain
similar to the present conditions. Therefore, the current
pathways of exposure are considered representative of expo-
sure pathways that will exist in the future if no action is
taken at the site.
The exposure assessment is organized around the contaminated
media. For each medium, the data available regarding expo-
sure point concentrations for each contaminant and the
affected populations are presented and discussed. In all
cases, the maximum contaminant concentrations observed in a
particular medium are used in the exposure assessment to
represent a point of "plausible maximum exposure." In addi-
tion, where exposures to maximum concentrations result in
risks greater than generally considered acceptable by EPA
(i.e., daily intakes greater than EPA reference doses (RfD's)
DE/CC11/014
3-3

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ENVIRONMENTAL RISK ASSESSMENT
INTRODUCTION
A report by the Kansas Department of Health and Environment
(KDHE, 1980) documented biological effects of mine drainage
on the Spring River and some tributaries to the Spring River
within the Cherokee County Site. KDHE (198 0) concluded that
the Spring River, from the confluence of Short Creek to below
the Kansas-Oklahoma border, was stressed by drainage from
lead-zinc mining areas in Missouri and Kansas. Center,
Turkey, and Short Creeks had continuously elevated concentra-
tions of heavy metals, and the chemical data available indi-
cated that Short and Center Creeks contributed the greatest
amount of mine-related metal contaminants to the Spring River
(Figure 3-1).
The biological effects cited by KDHE (1980) included the
almost total absence of biota in Short Creek, and reduced
diversity and absence of several pollution-sensitive aquatic
organisms from the lower reaches of the Spring River. Shoal
Creek did not appear to have been severely affected (KDHE,
1980) . However, Shoal Creek is a concern with respect to
potential environmental effects because natural caves near
Shoal Creek in the vicinity of Schirmerhorn Park are criti-
cal habitat for one or more species of salamanders listed as
endangered in the State of Kansas (Kansas, 1975 and 1987).
A 1982 EPA sampling program on Short Creek (EPA, 1982)
investigated the influence of discharges from a fertilizer
plant in Missouri and from abandoned mined areas along Short
Creek. The study concluded that high concentrations of toxic
metals and low pH have rendered Short Creek unsuitable as a
habitat for most aquatic life. The sources of pollutants
included a 70-acre phosphogypsum (calcium sulfate dihydrate)
waste pile at the fertilizer plant as well as abandoned
DE/CC11/014
3-42

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and chronic criteria for hardness dependent toxics such as
zinc. Zinc was the only toxic metal detected in a dissolved
state in Shoal Creek (Tables 3-28 and 3-30). Both of the
Shoal Creek samples collected in 1986 exceeded the more
restrictive state standard of 47 ppb for zinc, but the
upstream sample near Schirmerhorn Park did not exceed the
revised federal criteria while the downstream sample did
(Tables 3-26 and 3-30). Spring-fed tributaries to Shoal
Creek are known to discharge mine drainage downstream of
Schirmerhorn Park (EPA, 1986a) and the dissolved zinc con-
centration at the downstream station (Table 3-30) exceeded
the chronic but not the acute criteria. No impacts from
those discharges on biota in Shoal Creek have been
documented.
Shoal Creek is of particular concern because the Kansas Game
and Fish Commission wants to avoid impacts to a few species
of salamanders that are listed as endangered in Kansas
(Kansas, 1987) . Caves in the vicinity of Schirmerhorn Park
are believed to be the habitat of three endangered species;
the Cave Salamander (Eurycea lucifuga), the Graybelly Sala-
mander (Eurycea multiplicata), and the Grotto Salamander
(Typhlotriton spelaeus).
The Spring River basin is also habitat for two more Kansas
endangered species, the Central Newt (Notophthalmos
viridescens louisianensis) and the Nersho Madtom (Noturus
placidus). The Arkansas Darter (Etheostoma cragini) is
listed as a Kansas threatened species, and has been reported
in the Spring River basin in Cherokee County (Kansas, 1987) .
No impacts from mine drainage on any threatened or endan-
gered species have been reported by previous studies, and
none of these threatened or endangered species were observed
during the limited RI sampling activities.
DE/CC11/014
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Cherokee County - Galena Subsite
Mining Waste NPL Site Summary Report
Reference 4
Excerpts From Phase I Remedial Investigation Report, Air Quality Supplement,
Cherokee County, Galena Subsite - Final Draft;
EPA Region VII; August 1, 1986

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AIR INVESTIGATION
The Ambient Air Quality Investigation was conducted as one
of several sampling tasks during the Phase I Remedial Inves-
tigation (RI) at the Galena subsite, Cherokee County Site,
during late summer 1985, The report presenting the results
of this Phase I RI, except for the Air Quality, was completed
on April 23, 1986 and released by EPA at a public meeting m
Galena on Hay 2, 1986 (U.S. EPA, 1986). The air quality
investigation results were originally planned as Section 6
of that Phase I RI Report. However, the special analytical
techniques used to analyze the airborne particulate samples
required additional time, so the air quality investigation
results are presented in this supplemental report. This
Ambient Air Quality Investigation Report has the following
subsections:
6.0	Introduction
6.1	Sampling Methodology
6.2	Analytical Methodology
6.3	Results and Discussion
6.4	Conclusions
6.5	Summary
6.0	INTRODUCTION
Air quality sampling was conducted during a 14-day period m
August and early September 1985 at the Galena subsite of the
Cherokee County Site, Kansas. The objective of this study
was to measure the quantity and composition of the parti-
culate matter in the air and to determine, where possible,
the original sources of the particulates identified in the
air samples. During this period, 100 ambient air filter
samples and 16 bulk material samples of particulate sources
(i.e., soil, etc) were collected for analysis. The samples
were submitted to laboratories under contract to EPA's Con-
tract Laboratory Program (CLP). The South Dakota School of
Mines and Technology performed the x-ray diffraction (XRD)
analyses and NEA, Inc. Laboratory in Oregon performed the
x-ray fluorescence (XRF) and computer mass balance (CMB)
receptor modeling.
6.1	SAMPLING METHODOLOGY
6.1.1 Sample Locations
The sampling sites were located within potential source areas
and the samplers were isolated, where possible, to minimize
effects from other source areas.
The sampling locations were selected based on the following
criteria: 1) prevailing meteorological patterns, 2) close
proximity to potential sources, and 3) spatial distribution
6-1

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The samples were collected on 8- by 10-inch Teflon fiber
filters supplied by Millipore Corporation (Catalog
No. S09Q07A5). The Teflon fiber filters are required for
accurate XRF and XRD analyses.
6.1.3 Sampling Procedures
Sampling procedures are detailed in the Phase 1 Quality As-
surance Project Plan (QAPP) (U.S. EPA, 1985b) and the Labo-
ratory Analytical Protocol (LAP) (U.S. EPA, 1985e). Ambient
airborne particulate samples were collected at each location
every day of the sampling period at a set flowrate. Duration
of samples for the first 12 days was 20-28 hours. During
the last 2 days of sampling, the sample times were changed
to approximately 4 8 hours to increase the mass loading for
the x-ray diffraction analysis. Flowrates were approximately
20 standard cubic feet per minute (scfm) and sampling periods
were 24 to 48 hours, thus 800 to 1,600 cubic meters of
ambient air were passed through each filter. TSP sampling
by the EPA Reference method (EPA, 1982) , at 39-60 scfm for
24 hours, would produce sample volumes ranging from approxi-
mately 1,600 to 2,500 cubic meters.
Duplicate composite bulk material samples were collected at
each location at the start of the study. Eight to 10 sub-
samples of each ma^or upwind particulate source near the TSP
samplers, taken from the first 1 to 1 inch of surface mater-
ial, were taken randomly and composited at each location. A
second (duplicate) sample of each of the major particulate
sources (chat piles, road dusts, chat-type material, etc.)
upwind of the TSP sampler was collected in the same manner
as the first. Surface material samples (9272 and 9282) were
taken from 360° around the sampler. A stainless steel trowel
was used to place the sample into an 8-ounce glass bottle.
All samples were identified with a discrete sample number
and labeled with a sample tag. The bulk material samples in
8-ounce sample bottles were packed in coolers with vermicu-
lite and shipped to the contract lab.
All samples were handled, shipped, and documented as
described in the LAP (U.S. EPA, 1985e) and Phase 1 QAPP (U.S.
EPA, 1985b). Each ambient filter sample submitted for XRF,
XRD, and CMB analysis was placed unfolded in plastic zip-
lock bags and sealed. These samples were handled very care-
fully and never turned upside down. The samples were kept
in a horizontal position at all times, packed in coolers
with vermiculite, and shipped to the contract lab for analy-
sis. There was no apparent loss of particles from the fil-
ters onto or into the bags.
6-5

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for September 1984 were 9.2 mph and 159°, respectively (NOAA,
1984). The average wind speed during this investigation
(2.7 mph) is considerably less than the average for
August 1984 (7.0 mph). The average wind direction at the
Springfield Airport in August 1984 was 154° and is compar-
able to the August 1985 Joplin average of 142®. The Spring-
field, Missouri station is the closest location for official
weather data available to compare to the Galena, Kansas con-
ditions .
As previously mentioned, the wind speeds of 1 to 4 mph were
not considered a ma^or factor in suspending particulates
from the mined lands and other sources. However, particu-
lates from the potential sources at each site were suspended,
and therefore collected on the filters as evidenced by the
filter analysis. Vehicular traffic, wind gusts, emissions
from commercial facilities, and other factors suspended the
particulate material.
6.3.2 TSP Analytical Results
Total Suspended Particulate (TSP) concentrations for all of
the ambient samples at each site are shown in Table 6-3.
These 24-hour averages are reported in micrograms per cubic
meter. The highest, second highest, and mean 24-hour TSP
concentration for each sampling location are shown at the
bottom of this table. Tables C-l through C-8 in Appendix C
list sampling information, such as sample identification
number, sample date, weights, volume, etc. for each sample.
The Primary TSP National Ambient Air Quality Standard (NAAQS)
of 260 ug/ms (maximum 24-hour concentration not to be ex-
ceeded more than once per year) is established to protect
the public health. The Secondary TSP NAAQS of 150 ug/m3
(maximum 24-hour concentration not to be exceeded more than
once per year) is established to protect the public welfare
from any known or anticipated adverse effects. These stan-
dards for particulate matter are only applicable when 24-hour
TSP concentrations have been measured by the reference method,
(U.S. EPA, 1982) or by an equivalent method. The TSP method
used during this investigation is not considered a reference
or equivalent method, because the reference or equivalent
method requires flowrates to be 39 to 60 standard cubic feet
per minute (SCFM) and flowrates during this study were 20 SCFM.
Flowrates used during this study were reduced, because of
the Teflon filters used for XRF/XRD analysis. Consequently,
TSP levels are not directly comparable to the primary and
secondary 24-hour TSP NAAQS.
None of the TSP ambient air filter samples taken during this
sampling period exceed the primary NAAQS. There are three
6-11

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exceedances, however, of the 24-hour TSP secondary NAAQS as
follows:
24-HOUR TSP SECONDARY NAAQS EXCEEDANCES
Date	Site	TSP
08-28-85
08-29-85
08-28-85
Rural Chat Road/AIR-4
Residential/AIR-5
Chat Pile/AIR-6
153.4
154.9
156 . 6
Because there was not more than one exceedance at each loca-
tion the secondary NAAQS has not been violated.
Limited air quality data are available from other sources or
published literature to compare with current air quality
levels in the Galena area. Total Suspended Particulates
(TSP) measured in Galena from 1972 through 1976 indicate
that the primary and secondary NAAQS have been exceeded at
least once; however, not enough information is available to
tell if exceedances were more frequent (CH2M HILL, 1983) . A
study by the Kansas Department of Health and Environment
(KDHE) in 1983 measured TSP levels in Galena and found no
exceedances of the primary or secondary NAAQS (KDHE, 1984) .
TSP monitoring by KDHE from 1972 through 1976 and in 1983
was by the EPA reference method. TSP levels measured during
the 1983 KDHE investigation are in the same range as those
measured during this investigation.
As a general guideline, an annual geometric mean concentra-
tion in the range of 10 to 60 ug/ma has been found to be
representative of rural areas by the National Air Monitoring
(NAM) network. Typical urban values for 24-hour averages
range from 60 to 200 ug/m1. Data collected from previous
studies indicate that the Galena area has values higher than
typical rural areas but within the low range of values for
urban areas. Although not enough data were collected during
this investigation to determine the annual geometric mean,
it appears that this area could be considered a low urban
area for TSP.
Average concentrations for all of the samples taken during
the sampling period as shown in Table 6-3 range from 35.1 ug/m3
at the High School (AIR-7) site to 65.8 ug/m3 at the Chatpile

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during this investigation. The QA precision checks from
samplers 6A and 6B at the AIR-6 site were used instead.
6.3.3 X-ray Fluorescence (XRF) Analysis Results
Tables E-l through E-8 in Appendix E show the concentrations
of 34 elements found in each air sample, by sample location.
These are 24-hour averages and are reported as ug/m3. At
the top of each table, corresponding 24-hour average values
for wind speed, wind direction, temperature, and relative
humidity are listed. The highest concentration for each
element for the sample period is also noted.
The highest elemental concentrations occurred at each site
on August 29th and 30th when the wind speed was 4 mph and
the wind direction was 170° (south). The samplers at the
sites were located downwind (north) of nearby potential sour-
ces. There are no EPA or state standards for airborne ele-
ments except lead, as will be discussed later in this section.
These elemental data have been compared to data collected in
1983 by the Kansas Department of Health and Environment (KDHE)
at two locations in Galena, Kansas, from July 23 to Novem-
ber 26, 1983. A high volume sampler was installed by KDHE
in the Galena area, as shown in Figure 6-1, to collect TSP
and metals. All high volume TSP sample filters were analyzed
gravimetrically by KDHE with subsequent atomic absorption
analysis for iron, manganese, arsenic, barium, cadmium,
chromium, copper, lead, silver, zinc, beryllium, nickel, and
cobalt. In addition, ambient filter samples from a back-
ground station 4 miles south of Galena, Kansas were collected
(Figure 6-1). A comparison of the 1983 KDHE elemental data
and elemental concentrations measured during this investiga-
tion (1985 EPA study) are shown in Table 6-5.
The metal concentrations in Table 6-5 are reported as micro-
grams per cubic meter of air sampled. The mean and high
concentrations reported for each element are the arithmetic
average of all 24-hour samples and the highest 24-hour aver-
age value reported during the sampling period, respectively.
Although copper and cadmium concentrations observed at Galena
during 1985 were consistently higher than those observed by
KDHE in 1983, both the 1983 and 1985 concentrations are low
and do not indicate any contamination of concern.
An enriched manganese source contributed to all of the TSP
filters at the Eagle Picher site. This was probably due to
the manganese oxide used in their current processing activ-
ities .
6-16

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Table 6-5
COMPARISON OF 1983 KDHE and 1985 EPA
AMBIENT AIR QUALITY MEIAL CONCENTRATIONS
CHEROKEE COUNTY, GALENA SUBSITE
1963 KPHE Study
Galena
Background
Station
(Galena)
AIR-1
AIR-2
19B5 EPA Scudy
AIR-3
AIR-4
AIR-5
AIR-6
AIR-7
IRON
He an
High
MANGANESE
0.336
2.435
Mean
High
LEAD
Mean
High
0.021
0.044
COPPER
Mean 0.033
High 0.047
0.119
0.250
SILVER
Mean 0.001
High 0.004
0.582
1.679
0.082
0.359
0.014
0.039
0.070
0.418
0.001
0.008
0.359
1.879
0.150
0.553
0.064
0.173
0.036
0.068
0.015
0.027
0.456
1.277
0.012
0.028
0.185
0.235
0.037
0.065
0.016
0.040
0.733
1.726
0.018
0.034
0.385
0.825
0.042
0.068
0.011
0.024
0.866
2.276
0.021
0.056
0.035
0.580
0.044
0.086
0.020
0.035
0.497
1.495
0.014
0.031
0.228
0.647
0.034
0.046
0.009
0.028
0.051
1.705
0.013
0.028
0.105
0.170
0.053
0.084
0.013
0.030
0.457
1.120
0.012
0.023
0.171
0.267
0.030
0.051
0.026
0.013
COBALT
0.012
0.030
0.096
0.311
CADMIUM
Mean	0.001
High	0.007
CHROMIUM
Bean	0.194
High	0.994
NICKEL
Mean	0.498
High	1.610
BERYLLIUM
Hean	0.000
High	0.000
BARIUM
Mean	0.086
High	0.751
ARSENIC
Hean	0.000
High	0.004
0.006
0.020
0.118
0.534
0.001
0.005
0.124
0.416
0.312
0.990
0.000
0.010
0.089
0.933
0.001
0.004
N/A
N/A
0.082
0.224
0.021
0.048
0.007
0.014
0.003
0.005
N/A
N/A
0.187
0.323
0.003
0.010
N/A
N/A
0.035
0.160
0.014
0.046
0.006
0.011
0.003
0.807
N/A
N/A
0.235
0.400
0.001
0.006
N/A
N/A
0.061
0.079
0.021
0.024
0.007
0.012
0.004
0.008
N/A
N/A
0.138
0.349
0.001
0.004
N/A
N/A
0.197
0.053
0.030
0.056
0.008
0.014
0.005
0.008
N/A
N/A
0.212
0.272
0.005
0.008
N/A
N/A
0.052
0.095
0.024
0.044
0.006
0.011
0.002
0.005
N/A
N/A
0.178
0.316
0.003
0.008
N/A
N/A
0.095
0.025
0.016
0.035
0.007
0.012
0.003
0.007
N/A
N/A
0.172
0.274
0.005
0.010
N/A
N/A
0.039
0.063
0.012
0.028
0.006
0.009
0.457
1.120
N/A
N/A
0.113
0.247
*KDHE data for 1983 from (KDHE, 1964).
N/A - Not Analyzed
Note: All values reported in ug/m3
GLXS22/45
o-/7

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Nickel and chromium are less than 1983 KDHE concentrations.
Most of the remaining elemental concentrations are in the
same ranges as observed by KDHE in 1983.
XRF analysis results are shown in Appendixes F and G for
ambient filters and aerosolized bulk material samples, re-
spectively. The results are reported in ug/cm3, ug/filter,
and percent. The ug/cma values are based on an effective
filter area of 406 cma. The plus or minus values listed
under the ug/cma column are estimates of uncertainties that
include absolute calibration uncertainties (5 percent) f posi-
tioning, and replication uncertainties, as well as uncertain-
ties in standards and counting statistics. The detection
limits for each element can be estimated by multiplying the
uncertainty value shown in Appendix F by two.
The ambient filters were analyzed for lead and 33 other ele-
ments by XRF. Flowrates used during this investigation were
20 SCFM and do not meet the EPA lead method minimum flowrate
criterion of 39 SCFM. Consequently, XRF analyses for lea :,
performed on the ambient air samples collected during this
investigation, are not directly comparable to the EPA meth-
ods used to monitor lead concentrations in ambient air (U.S.
EPA, 1979). Table €-5 shows the mean and maximum lead concen
trations observed at the Galena sites during this investi-
gation. Tables E-2 through E-8 in Appendix E show the lead
concentrations (in ug/m3) for each ambient filter per site.
Precision calculations for the paired lead sample data at
site AIR-6 have been determined as shown in Table 6-6. As
shown in Table 6-6, the average percent difference of -9.2
(d^) is less than the TSP percent difference. This indi-
cates that, although the total mass difference is slightly
greater than desired, the elemental (lead) difference at the
collocated site is within the acceptable limits.
The primary and secondary National Ambient Air Quality Stan-
dards (NAAQS) for lead and its compounds, measured as ele-
mental lead are each 1.5 micrograms per cubic meter, maximum
arithmetic mean averaged over a calendar quarter. Although
a direct comparison between the lead data as presented in
Tables E-2 through E-8 cannot be made because the sampling
period does not constitute a calendar quarter, it can be
seen that the lead data from this sampling period are still
considerably lower than 1.5 ug/m*.
The lead concentrations observed at Galena in 198 5 were in
the same range as those observed by KDHE during their 1963
study. Ambient lead data from July through November 19 83,
obtained by the Kansas Department of Health and Environment
(KDHE) in the City of Galena, reflect a mean concentration
of 0.119 ug/mJ, and a high of 0.25 ug/m' (Table 6-5). The
1983 KDHE study for lead and its compounds was performed in
accordance with EPA methodology (U.S. EPA, 1979). The KDHE
6-18

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lead data therefore, is directly comparable to the NAAQS
standards.
Compared to the NAM Network average lead values of 0.1 to
1.0 ug/mJ for rural areas and 0.5 to 10.0 for urban areas,
the data collected during this investigation show this area
to be in the low rural range.
Spatial distribution of lead and several other elements was
very similar in the Galena subsite area. Lead and several
other elements were slightly higher at the Rural Chat Road
site (AIR-4) than at the Residential (AIR-5) and High School
sites (AIR-7).
6.3.4 X-ray Diffraction Analysis Results
The XRD results are presented in Appendixes I and J for am-
bient filters and bulk samples respectively. In Appendix I,
the mineral composition of the filter sample is listed at
the top of the page as a fractional composition. These com-
positions are based on the assumption that the species mea-
sured, including the amorphous carbon, account for 100 per-
cent of the mass. These concentrations are also based on an
assumed mineralogical composition, 100 percent particle trans-
fer efficiency, and the assumption that all of the mass is
represented by the measured minerals plus the measured amor-
phous carbon. The XRD detection limits are shown in Table
6-1 for both the bulk material and filter samples.
A complete list of minerals and their chemical formulas is
shown at the front of Appendix I. The elemental composition
of each mineral, however, is not based on these formulas,
but is instead based on empirical tables of average composi-
tion as determined by the contract laboratory.
The filters used for x-ray diffraction (XRD) mineralogy of
the ambient air samples were collected during the period
from August 26 to September 1, 1985. There was a heavy rain
on August 22 (4.28 inches) followed by a drying period through
the collection period. There was a change in the mean daily
wind direction from a mean of 133 for the first three days
to a mean of 170 the last four days. Mean daily wind speed,
however, remained about the same. The mean daily relative
humidity decreased from 71 percent to 50.9 percent and aver-
age temperature increased from 65.9° to 86.4° F during the
collection period. Therefore, the site was getting drier
and warmer through the collection period.
Twenty-seven minerals were quantitatively determined in the
XRD analysis of airborne particulates (ambient air filters)
and bulk source material (samples of soil, road dust, etc.).
The bulk material samples were collected from various loca-
tions near six Galena sites, as described earlier in this
6-20

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Cherokee County - Galena Subsite
Mining Waste NPL Site Summary Report
Reference 5
Excerpts From Phase I Remedial Investigation Report, Cherokee County, Galena Subsite
Final Draft; EPA Region VII; April 23,1986

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FINAL DRAFT
PHASE I
REMEDIAL INVESTIGATION
REPORT
CHEROKEE COUNTY
GALENA SUBSITE
EPA WA No. 127.7LB9.0
April 23, 1986

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subsite first because most types of mining related activities (vertical shafts,
milling wastes, subsidences, and smelting) occurred at Galena and the Galena
area includes a relatively large population that is exposed to the mining
related problems. Evidence of mining impacts on the surface waters, ground-
waters, and agricultural fields in the Galena area has been suggested or docu-
mented by prior studies (EPA, 1984c).
The Galena subsite is a nine square-mile area in the east-central portion of the
Cherokee County site (Figure ES-1). The town of Galena, a residential community
of 3,588 (1980 U. S. Census) is in the center of the subsite. Lead and zinc
mining began in the Galena area about 1875 and continued into the 1960's. A
smelter operated along Short Creek just north of town from the 18901s until the
early 1960's. Sphalerite (zinc sulfide) and galena (lead sulfide) were the
principle ores, although many other types of metallic sulfides are found in
association with the galena and sphalerite (Brichta et al., 1967).
Today, the Galena area is underlain by abandoned mines and surrounded by large
areas of milling wastes, locally called chat. Numerous subsidence features and
open mine shafts, many filled with water, are present in and around the town of
Galena. During the active mining years, water was continually pumped out of the
mines because the ore is located in the same rock formations that contain the
area's shallow aquifer. When mining ceased, the mines filled with water as a
result of natural groundwater recharge and surface water inflow through mine
shafts and subsidence areas.
The primary source of pollution is the residual metallic sulfides in the aban-
doned mine workings and chat piles. Oxidation of these metallic sulfides
through exposure to air or oxygenated water results in remobilization of the
metals as dissolved compounds, and an increase in acidity. The resulting metal-
laden acidic water, called acid mine drainage (AMD), contaminates the ground-
water, fills mine shafts and subsidence depressions, and surfaces through
springs, etc. resulting in contaminated rivers, creeks, and lakes.
Ore processing methods in the Tri-State District generated millions of tons of
chat. Chat piles 100 ft. or more high and covering tens of acres dominate the
landscape in the western portion of the Cherokee County site. In the Galena
area most of these chat piles have been removed for reprocessing or used for
construction aggregate. However, while a few unused chat piles still exist,
hundreds of acres around Galena remain covered with chat several feet deep.
Rainwater percolating through these chat areas also forms AMD.
The smelter that operated at Galena was a potential source of metal-laden par-
ticulate emissions. Surface soils downwind of the former smelter contain cad-
mium, lead, and zinc that would occur in smelter emissions. Furthermore, the
concentrations of these metals generally decrease as distance from the smelter
increases. These metals can be transported by physical and chemical processes
into plants and animals, including man, and further dispersed as airborne dust
or sediments in surface runoff.
ES-3

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1.0 INTRODUCTION
1.1 Site Background Information
1.1.1	Cherokee County Site
The Cherokee County site represents the Kansas portion of the
Tri-State Mining District. This mining district was one of the
richest lead and zinc ore deposits in the world and covered about 500
square miles in Oklahoma, Kansas and Missouri.
Because of the large si2e of the project area, the Cherokee County
site was divided into six subsites with a total combined area of 25
square miles. These subsites are designated as areas near Galena,
Badger, Baxter Springs, Lawton, Treece, and Waco (Figure 1-1). The
EPA directed work to start at the Galena subsite because of the popu-
lation density (the town is in the center of the site), the fact that
most types of mining activities occurred at Galena, and prior studies
had produced some data for the area. This Phase I Remedial
Investigation (RI) report is concerned only with the Galena subsite.
Ore was first discovered in the Tri-State Mining District in 1848.
The first significant mine in Kansas was in Galena, where ore was
discovered in 1876. A smelter was built along Short Creek in the
1890's. The general area of the original smelter was used for
smelting facilities until around 1961 when the facility was converted
to produce sulfuric acid for use by adjacent industries. Lead and
zinc mining flourished in Cherokee County from the late 1800's through
the 1940's. The peak production year within the Cherokee County site
was 1926 when 28,000 tons of lead and 126,000 tons of zinc were pro-
duced. Mining activity decreased in the 1950's and many of the mines
were closed. There was a short resurgence in the 1960's, but area
mining ended when the Swalley Mine near Baxter Springs, the last major
commercial mine, closed in 1970. A summary of the chronology of
mining in Cherokee County is presented on Table 1-1.
1.1.2	Galena Subsite
The Galena subsite in Cherokee County, Kansas, is situated approxi-
mately seven miles west of Joplin, Missouri. Access to the subsite is
by way of U. S. Route 66 west of Joplin, Missouri or Interstate 44.
The U.S.G.S. 7.5 minute topographic maps covering this subsite are the
Baxter Springs, KS and Joplin West MO-KS quadrangles.
The Galena subsite is a 9 square mile area in the east central portion
of the Cherokee County site (Figure 1-1). The subsite centers around
the town of Galena, Kansas, a residential community of 3,588 (1980
U.S. Census) and includes the oldest lead and zinc mining activity
within Kansas. Sphalerite (zinc sulfide) and galena (lead sulfide)
were the important commerical ore minerals. Pyrite and marcasite
1

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1.1.3.2 Geology
The geologic section for Cherokee County includes rocks of
Mississippian age and older. A generalized stratigraphic
section is presented on Table 1-2. The Ordovician and
Mississippian strata are of greatest interest to this
Remedial Investigation. The Ordovician rocks are largely
dolomites and sandy dolomites and contain the deep regional
confined aquifer. The Mississippian sediments are shales
near the base of the section, and cherty carbonates higher
in the section that contain the shallow aquifer. In the
Galena area the confining aquitard above the deep aquifer is
composed of Mississippian shales (Table 1-2) while south and
west of Galena the Devonian aged Chattanooga Shale is pre-
sent and becomes a major part of the aquitard.
1.1.3.3	Groundwater
A review of prior studies indicates that two aquifers exist
in the Galena area, a shallow water-table aquifer and a
deeper confined aquifer (EPA, 1984c).
The shallow aquifer includes the Warsaw Limestone, the
Burlington-Keokuk Limestone and the Fern Glen Limestone and
is the equivalent of the Boone aquifer in Oklahoma. This
aquifer is under water-table conditions in the vicinity of
the Galena subsite. These limestone strata yield little
water in areas where the strata are massive, but in areas
where solution channels, breccia, and fractures occur, the
yields are adequate to good. The ore bodies and mine
workings are associated with the Warsaw and Keokuk
Limestones within the aquifer.
The deep aquifer is generally under confined conditions and
is considered to be all the rocks of the Ordovician Arbuckle
group. The deep aquifer is the source of municipal ground-
water supplies in the site area. This deep aquifer includes
the Cotter-Jefferson City Dolomite, the Roubidoux Formation
and the Gasonade Dolomite. The Roubidoux formation, fre-
quently referred to as the Roubidoux aquifer, is probably
the most productive zone of the deep aquifer.
Transmissivity of the Roubidoux ranges up to 27,000 ft.2
per day (Spruill, 1984).
1.1.3.4	Surface Water
The Galena subsite is drained by Spring River, Short Creek,
Shoal Creek and their tributaries (Figure 1-1). Spring
5

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Burlington-Keokuk Limestone and the Fern Glen Limestone and is the
equivalent of the Boone aquifer in Oklahoma. This aquifer is under
water-table conditions in the vicinity of the Galena subsite. The ore
bodies and mine workings are associated with the Warsaw and Keokuk
Limestones within the shallow aquifer (Brockie, et , 1967).
Natural brecciated zones and collapse breccias caused by mining near
Galena act as zones of high permeability. Outside the brecciated
zones, groundwater inflow to the mines and brecciated zones is
controlled by the permeability of the limestones (Spruill, 1984). The
reported median thickness of the shallow aquifer is approximately 275
ft. (Spruill, 1984).
An aquitard consisting of the Mississippian Northview Shale and
Compton Limestone separates the shallow and deep aquifers. The
reported median thickness of the Northview shale and Compton limestone
total 27 feet.
The deep aquifer is generally under confined conditions and is con-
sidered to include all of the Ordovician Arbuckle group. This inclu-
des the Cotter-Jefferson City Dolomite, the Roubidoux Formation and the
Gasonade Dolomite. The Roubidoux formation is reported to be the most
productive zone of the deep aquifer and is frequently referred to as
the Roubidoux aquifer (Spruill, 1984). Thickness of the deep aquifer
generally exceeds 1,000 ft.
Groundwater is used extensively within the Galena subsite through both
public wells and private wells. The public wells obtain water from
the deep confined aquifer. The private wells obtain water from the
shallow water table aquifer.
Based on the water supply survey performed in July and August, 1985,
the limit of the Galena Municipal Water Service area supplied by
public wells is indicated on Figure 4-1. About 3,600 residents are
serviced by the public water supply. The primary source for the
Galena Municipal water supply is a 1,260 ft. deep well drilled in 1979
into the confined deep aquifer. This well is located in the vicinity
of 6th and Wood Streets. Three older wells located around 11th and
Wood Streets serve to supplement the water supply when necessary, but
are not normally used. These older wells were drilled to a depth
similar to the new well.
Within the limit of the water supply survey area (Figure 4-1), but
outside the municipal water service area, over 95% of the residences
were surveyed. In this area 74 private wells, obtaining water from
the shallow aquifer and serving 234 residents, were located. All of
the private wells were used as a potable water source. Private well
depths range from 22 feet to 425 feet based on the water supply sur-
vey. Most of the private wells are in excess of 100 ft. deep.
29

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and 015 were most likely drawing water from the same aquifer, but the
results from comparing the 3 well pairs were inconclusive as to
whether the dug wells and drilled wells were drawing water from the
same shallow aquifer.
4.5 Groundwater Chemistry
4.5.1 General Groundwater Chemistry
The mining of ores within the shallow aquifer zone in the Galena sub-
site, and the resultant removal and fracturing of material, has
resulted in the creation of highly transmissive zones and mine voids.
This in turn has increased both the groundwater storage and flow pro-
perties of the aquifer. Also, fractured rock areas, chat piles, sub-
sidence areas, and unvegetated abandoned mine lands have created
conditions that promote increased infiltration into the shallow
aquifer.
The geochemical system in the project area is principally an acid
sulfate system generated by the oxidation of sulfide minerals. When
groundwater contacts the metallic sulfide ores remaining in the mines
and mine wastes, sulfate, acid, and metal ions are produced. The
metal ions may include lead (from galena-PbS), zinc (from
sphalerite-ZnS), iron (from pyrite-FeS), or other metals depending
upon the type of ore undergoing the reaction and the types of trace
elements associated with that ore. For example, sphalerite in the
Galena area may contain up to 1* cadmium. As acid (H+ ions) accumula-
tes in the water, the concentrations of dissolved metals also
increase.
Tne general geochemical processes in an acid sulfate system are
discussed briefly in the following paragraphs to provide some insight
into how acidic water is generated and how the heavy metals go into
and out of solution.
The oxidation of pyrite (iron sulfide) is one of the most effective
acid producing weathering reactions. The process has been described
in detail by Nordstrom (1985). The overall reaction is commonly
described as follows:
(1)	FeS2 + 15/4 02 + 7/2 H2
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7.0 to 6.0) causes the hydrogen ion concentration to change by a fac-
tor of 10. pH values below 7.0 indicate increasingly acid conditions
and pH values above 7.0 indicate increasingly basic conditions. In
addition to changing pH by adding free hydrogen ions (H+), the pH can
be changed when chemicals such as iron or aluminum sulfates release
hydrogen ions to the water sample and thus increase acidity. Total
acidity is a measure of the aggregate potential of a water sample to
release hydrogen ions (acid) when the pH is raised to 8.3 from its
existing pH. Thus, total acidity provides a means of relatively eva-
luating the total acid production potential of water samples. Total
alkalinity is a measure of the aggregate potential of a water sample
to neutralize hydrogen ions (acid) when pH is lowered to 4.5 from its
existing pH. Thus, total alkalinity provides a means of relatively
evaluating the total neutralizing potential of water samples.
The pH of a water sample provides an assessment of whether a sample is
acid or basic, while total acidity and total alkalinity can be used to
indicate the relative potential for acid production or acid neutrali-
zation. Total alkalinity concentration minus total acidity con-
centration (net alkalinity) is used as an indicator of the net
potential for acid production or acid neutralization. High net alka-
linity values indicate the water has an excess of acid neutralizing
chemicals. Low net alkalinity values indicate an excess of acid pro-
ducing chemicals in the water sample.
4.5.2 Galena Subsite Groundwater Chemistry
The majority of the private well and groundwater discharge samples in
the Galena area ranged in pH from 6.5 to 7.5, near the neutral pH of
7.0 (Figure 4-4). All but one of the mine shaft samples had pH values
lower than 6.5. Two private well samples (001 and 002) located in the
southwest corner of the subsite (Figure 4-2) had pH values below 6.5.
Well 001 had a pH of 4.1, while well 002 had a pH of 5.6. These wells
are located downgradient and very close to abandoned mine workings.
Generally the mine shaft and groundwater discharge samples were lower
in net alkalinity (i.e. had a higher potential to release acid) than
the private well samples (Figure 4-4). Thus, water within mine shafts
and originating from groundwater discharges accumulated more acid pro-
ducing materials and/or had not contacted sufficient limestone (acid
neutralizing material) to neutralize the acid potential. Private well
samples, with the exception of well 002, did not exhibit total acidity
values reflecting contact with acid producing materials. Water in
most private wells apparently had not been influenced much by acid
mine waters, or the water had passed through limestone strata which
buffered the impact. Well 002 exhibited a total acidity similar to
mine shaft 040, but unlike the water in mine shaft 040, the water in
well 002 had apparently contacted sufficient limestone so that
38

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lead and net alkalinity to see if mine-related impacts could be
detected. Manganese and mercury were not compared because they were
present at only a few locations sampled. Nickel was also not compared
because it was present in low concentrations that did not vary across
the site.
The water quality in mine shafts and upgradient, adjacent, and
downgradient wells were compared by calculating average concentrations
for each of these four groups. Average concentrations and statistical
ranges for the averages (951 confidence intervals) are presented in
Table 4-4.
The comparisons indicate that the downgradient wells have at least an
order of magnitude higher concentration of dissolved zinc than upgra-
dient wells. Downgradient wells also have higher concentrations of
dissolved zinc and are more acidic than adjacent wells. Dissolved
zinc, lead, and cadmium concentrations are higher in mines than in
downgradient wells. These results are shown graphically in Figure 4-7
for dissolved zinc and iron, Figure 4-8 for dissolved cadmium and
lead, and Figure 4-9 for net alkalinity. Although mine water has
relatively high concentrations of dissolved zinc, lead, and cadmium
when compared to upgradient and adjacent wells, only zinc generally
appears more abundant in wells downgradient of the mined areas. This
is due, at least in part, to the fact that zinc is more mobile in the
existing geochemical system than lead, iron, etc. Also, the mobility
of zinc and cadmium is about the same, but zinc is much more abundant.
Zinc mobility is related to the greater resistance of zinc to precipi-
tation in the geochemical reactions occurring in the groundwater
system.
Many metals do not show any identifiable change between upgradient and
downgradient wells, but do show variations in concentration between
downgradient wells across the site. This is probably due to local
variations in geology.
The groundwater in the southwest portion of the site, centered on Well
005, has variable groundwater chemistry, as shown by upgradient Wells
003, 004, 005, and Oil. One or more of these upgradient wells have
higher concentrations of antimony, barium, manganese, and tin than do
most other upgradient wells. Wells 003, 004, 005 and Oil have high
total alkalinities, total acidities below detection, pH values between
6.5 and 7.5, and sulfate concentrations averaging 35 mg/1. These
values do not suggest an influence by mined areas.
Three separate comparisons were made between upgradient and downgra-
dient wells and an intervening mine shaft or discharge, using analyti-
cal results from selected sampling locations (Table 4-5}. Table 4-5
shows that zinc increased downgradient in each case, net alkalinity
decreased, and cadmium increased downgradient in one comparison and
iron increased downgradient in another comparison. For most parame-
ters there was no appreciable difference between the upgradient and
45

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downgradient wells, even though the intervening mine Shaft or
discharge exhibited the highest concentrations (for example iron,
zinc, and lead). Inspection of the results presented in Appendix A
also indicates dissolved nickel, manganese, and cobalt increased in
downgradient well 045, but not in downgradient wells 021 or 001. No
other metals exhibited increases in downgradient wells.
The data presented above indicate that zinc is the only chemical which
appears more abundant downgradient of mines. Zinc concentrations
increase downgradient of mined areas in the southwest, central, and
northwest sections of the site. As discussed above, this is a reflec-
tion of the relatively high mobility and high concentration of zinc.
Metal-laden acid water, generated through contact with mine wastes or
residual minerals left in the rock after mining, might be expected to
move downgradient with only slight changes in concentration. However,
this appears to be modified in the present situation because the acid
water contacts acid neutralizing limestone materials or mixes with
alkaline groundwater. The result of these carbonate-bicarbonate buf-
fering reactions is an increase in the pH and conversion of the metals
to insoluble or less soluble compounds, leading to the formation of
precipitates. These precipitates may, at least locally, reduce the
available neutralization sites on the limestone in contact with acid
water.
4.5.2.2	Water Quality of Galena City Water
A water sample was obtained from the Galena municipal water system
(095) from the deep aquifer in August to document the quality of water
being used as an initial decontamination rinse. The total metals ana-
lytical results showed the presence of zinc (210 ug/1) and traces of
manganese, barium, and iron. Lead and all other constituents were
below analytical detection limits. Considering dissolved metals, the
analytical results showed only a trace of iron. All other dissolved
constituents were below analytical detection limits. The sample met
both primary and secondary drinking water standards for all consti-
tuents analyzed.
4.5.2.3	Water Quality in Mine Shafts
Water samples were collected at surface, mid-depth and bottom levels
from mines shafts 028, 031, and 037 to evaluate chemical concentration
changes with depth. Analytical results are presented in Appendix A.
The sample numbers at each mine are:
Mine 028
Mine 031
Mine 037
Surface
Mid-Depth
Bottom
028
029
030
031
032
033
037
038
039
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occur prior to Inflow into surface streams, the alkalinity and pH of
the stream water will be decreased and dissolved metal concentrations
will increase in response to the inflow of acidic metal-laden water.
Mine shaft samples and groundwater discharges exhibit elevated con-
centrations of zinc, lead, cadmium, iron, and manganese. Zinc is one
of the most mobile metals in the existing system and the only chemical
which generally appears in private wells at higher concentrations
downgradient of mines than upgradient. The high lead and cadmium con-
centrations found in mine shafts did not appear in the private wells
sampled. Manganese was found in only a few private wells. These
results indicate that the majority of metals are less mobile than zinc
and many metals are precipitated prior to entering private wells.
However, low metal concentrations in downgradient wells may also
result from the absence of fractures or other flow pathways between
the mined area and these wells. Iron was found in mine shafts and
groundwater discharges, and 1n private wells. This suggests that iron
may be elevated 1n the shallow aquifer because of the iron in natural
soils and rocks In the area, as well as the iron that 1s derived from
the Iron pyrlte associated with the lead and zinc areas.
Areas of groundwater with elevated concentrations of metals occur in
the southwest portion of the site (near Well 001), along the tributary
to Short Creek west of Galena near nine shafts (027 and 031), and in
the northwestern portion of the site (near well 045) (Figure 4-3).
Although Phase I studies at 6a1ena did not include specific investiga-
tions to determine if a connection night exist between the shallow and
deep aquifers, this potential does exist (Sprul11, 1984 and OWRB,
1983). There nay be natural leakage through the relatively thin
aquitard, through conduits forned by old wells and exploratory boreho-
les, or through natural breaks in the aquitard.
4.7 Soils
4.7.1	General Description
Much of the 6alena subsite area is mantled by a layer of cherty gravel
that has resulted from the weathering of the Mississippian limestones.
The soils of the area are often thin and rocky (McCauley, et al.,
1983). The Soil Conservation Service Identifies the hillside and
upland soils near Galena as follows: Clarksville Cherty loam
(somewhat excessively drained) and N1xa Cherty Loam (moderately well
drained). These soils have pH values ranging from S.O to 6.0. At the
sampling locations the soils generally contained chert fragments and
at depths below about 12 inches a large fraction of the soil was com-
posed of chert fragments. In the Galena area, lowlands soils consist
of Cherokee, Dennis, Vertlgree, and lanton silt loams.
4.7.2	Sample Locations and Methods
The soil sampling conducted during Phase I studies was limited to
testing soils downwind of the former Galena smelter. Previous
investigations (Irwin, 1971; Lagerwerff, 1972) concluded that elevated
53

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concentrations of heavy metals existed 1n the vicinity downwind of the
former Galena smelter. The current investigation was performed to
confirm the elevated soil concentrations by evaluating the changes in
heavy metals with distance downwind of the smelter, and the changes
with soil depth. Soil sampling locations were selected based on pre-
vailing wind direction and distance from the former Galena smelter
(Figure 4-10). To assess the change in residual heavy metals with
depth, composite samples were taken within a 2,500 square foot area at
two depth ranges at each location: surface soils at 0 to 6 in., and
deep soils at 12 to 18 1n. Sampling methods are fully discussed m
the Phase I QAPP (EPA, 1985b), and Section 3.3 of this report.
4.7.3 Sample Results
The soil data Indicate a relationship between the concentrations of
some heavy metals in the soils and distance from the smelter area.
The levels of lead, zinc and cadmium decreased with distance from the
area where the smelter had been located, and these metals would be
expected to occur in the gaseous emissions from a lead/zinc smelter.
Lead in surface soils varied from 510 to 68 mg/kg, zinc from 1,100 to
230 mg/kg, and cadmium from 12 to 3 mg/kg (Figure 4-10). The highest
levels of these metals were found at locations 050, 046 and 047, all
within about 3/4 mile of the smelter. This narked decrease in metals
with distance from the foraer smelter suggests that the source of the
metals may be fallout of smelter emission. However, other potential
causes for the observed results are deposition of airborne par-
ticulates blown from the general area of mining activity south of the
smelter, and natural variation in heavy metals due to distance from an
ore body.
A relationship also existed between lead, *1nc and cadmium content and
soil depth. Without exception, the levels of these metals «re lower
at the 12 to 18 1n. depth than at the 0 to 6 1n. depth. Lead levels
were as such as 13 tines greater 1n shallow than 1n deep soil samples.
Zinc and cadnlum generally showed smaller changes with depth, indi-
cating that these metals are nore mobile than lead with respect to
transport through soils. Z1ne concentrations In the shallow samples
were four tines the deep level and shallow cadmlun concentrations were
three tines the level of corresponding deep soi1 samples. Although no
background soil samples were obtained for this investigation, samples
were taken for a previous study (lagerwerff, 1972) from areas pro-
tected fron exposure to aerial fallout. The results suggest that
background soils contained natural levels of lead, zinc and cadmium
that vary sonewhat with location, but do not vary significantly with
sample depth. This Information reinforces the hypothesis that the
relatively high concentrations of lead, zinc, and cadmium in shallow
soils 1s due to aerial deposition and not natural causes. Data for
deep soil samples may Indicate that lead, zinc, and cadmium have been
transported from shallow soils to deeper soils by infiltrating surface
water.
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5.0 SURFACE WATER INVESTIGATION
5.1	Galena Subsite Drainage
The Galena subsite is drained by Spring River, Short Creek, Shoal
Creek and their tributaries (Figure 5-1). Spring River and Shoal
Creek are impounded by two adjacent dams. The impoundment formed by
these dams, Empire Lake, is located three miles west of Galena. The
impoundment is used as a cooling water source and was originally built
for a source of hydroelectric power. Water levels on Spring River and
Shoal Creek upstream of the impoundment are influenced by the level of
Empire Lake.
The major drainage basin in the Galena study area is the Short Creek
watershed. Short Creek originates in Missouri, then flows through the
northern portion of the subsite and enters Spring River west of Galena
(Figure 5-1). The water level in Empire Lake influences the water
level at the confluence of Short Creek and Spring River. The majority
of the Short Creek watershed is located in Missouri. A major tribu-
tary to Short Creek, referred to as tributary "B", flows south and
west of the City of Galena. Another main tributary, referred to as
tributary "A", flows into Short Creek northeast of Galena. The lower
end of tributary "A" drains the mined area north of Galena that is
called Hell's Half Acre.
An unnamed tributary to Spring River, referred to in this report as
tributary "C", drains the southwestern portion of the subsite. A
substantial portion of the headwaters of this tributary is in land
disturbed by mining, with many chat-covered areas. At the northern
and southern sections of the subsite, runoff from some small areas
disturbed by mining drains directly to Spring River and Shoal Creek
respectively.
The stream sediments associated with Short Creek and its tributaries
are typically coarse granular materials originating from the mine
disturbed areas. Similar coarse sediments form the stream bed of
Spring River and the upper reaches of Shoal Creek. In the relatively
calm waters of Empire Lake and Lower Shoal Creek, the sediments are
primarily fine grained silt and clay.
5.2	Sampling Locations and Methods
5.2.1 Surface Water
Surface water sampling locations were selected to evaluate the water
quality of Short Creek, Shoal Creek, Shawnee Creek, Spring River and
Empire Lake. Surface water samples were obtained at 28 locations bet-
ween August 10 and August 19, 1985. The sampling locations are shown
on Figures 5-1 and 5-2.
57

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was in the dissolved form, indicating that most of the lead was
apparently transported downstream as a suspended solid.
Nickel concentrations varied in Short Creek, and almost all of this
metal was in the dissolved state. Nickel was undetected at 073, 110
ug/1 at 072, and decreased to a range of 60 to 70 ug/1 in the lower
reaches. Nickel was present in tributary "B" varying from trace
amounts upstream to 83 ug/1 at the downstream location.
The pH of Short Creek decreases downstream from mildly alkaline (pH
7.4) to mildly acidic (pH 6.4) (Figure 5-6). The net alka-linity
decreases downstream from 55 to 13 mg/1. Tributary "B" shows the same
trend of decreasing pH and decreasing net alkalinity as this water
flows downstream through mine disturbed areas. The exception to this
general trend on Short Creek is at 072 near the state line where pH
and net alkalinity were lowest.
On Short Creek (Figures 5-6 and 5-7), the lowest concentrations of
calcium, manganese and sulfate (30 mg/1, 18 ug/1 and 35 mg/1 respec-
tively) were found at the upstream sample location (073). The highest
concentrations of calcium, manganese, and sulfate (150 mg/1, 1,200
ug/1, 378 mg/1 respectively) were found at the next sample downstream
(072). These chemicals then decrease in concentration as Short Creek
flows downstream toward Spring River. In tributary "B", manganese and
sulfate increase in concentration proceeding downstream. On Short
Creek and its tributary, 90 to 100X of the calcium and manganese are
in dissolved form.
Sample 066 on tributary UC" (to Spring River) contained relatively low
concentrations of lead, zinc, and cadmium when compared to most other
subsite drainages.
5.4.2.2 Discussion
Low flow water quality changes on Short Creek indicate that zinc and
cadmium concentrations increase substantially downstream. Excluding
concentrations from tributary "B", the sampling results indicate that
most of the zinc and cadmium originate between the Kansas-Missouri
state line (073) and the Main Street bridge in Galena (076).
Abandoned mine lands both north and south of Short Creek drain into
the creek in this reach. South of this stream section is an inten-
sively mined area known locally as "Hells Half Acre." Mine water from
these areas entering Short Creek by subsurface flow is probably a
major contributor to the elevated zinc and cadmium observed in the
stream. A stream capture at 071 may be responsible for a significant
amount of water entering the mines of Hell's Half Acre and is
discussed in Section 5.4.5.2.
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Tributary "B" to Short Creek, which lies south and west of Galena,
contained the highest concentrations of lead, zinc, cadmium and nickel
observed in stream water during 1985. The concentration of dissolved
zinc in this stream also was greater than that in the mine shafts
sampled. Dissolved zinc concentrations in the tributary were exceeded
only by those found in the strip mine pit near the tributary mouth
(station 069). Considering the substantial increase in zinc con-
centration in Short Creek as it passes through the abandoned mine land
area northwest of Galena and past this strip mine, it is likely that
the groundwater from the area around the strip mine enters Short
Creek. Based on the data for total and dissolved lead in tributary
"B" and Short Creek, lead appears to precipitate upon entering the
oxidizing, more alkaline environment in Short Creek. This is rein-
forced by the fact that lead does not appear in the water of Short
Creek, but does appear as a solid in Short Creek sediments (Section
5.5).
The relatively high flow of tributary "B" is probably associated with
the extensive underground mine workings adjacent to and beneath this
stream. Mine water is believed to flow freely through the subsurface
in response to the groundwater gradient, particularly when groundwater
levels are high, and contributes water and contaminants to Short Creek
to tributary UB" and to the lower end of Tributary UAU. The water
quality of tributary "B" is generally comparable to mine shaft samples
taken in the area, and it is likely that some of the tributary flow
originates as drainage from area underground mines. The area encom-
passing the underground mines potentially contributing to tributary
"B" drainage is large, possibly on the order of one to two square
miles.
A major source of chemical loading to Short Creek is located between
stations 072 and 073 near the State Line. Large concentrations of
calcium, manganese, sulfate, sodium, and nickel are contributed bet-
ween these sampling points. All of these constituents then decrease
in concentration farther downstream as Short Creek flows through the
subsite. This decrease in concentration is probably due to two fac-
tors; dilution as Short Creek receives surface water and groundwater
with lower concentrations of the same constituents; and removal from
solution by chemical precipitation. Evidence of this precipitation
was observed in the field as a whitish coating on stream sediments and
a milky appearance to Short Creek. Zinc and cadmium also appear to
originate in this area, but in concentrations lower than that
generally found on the subsite. The Farmers Chemical Company plant is
located on this reach of stream, along with areas of mining disturbed
land.
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Changes in Short Creek water quality between low and high stream flow
conditions is indicated by comparing 076, a low flow sample taken near
the Main Street bridge across Short Creek, and 082 taken about 1,800
ft. upstream of the bridge after the rainfall event. The difference
in flow between the low flow and high flow sampling dates was 8.3
cubic feet per second (3,700 gal. per minute). During high flow,
zinc, cadmium, sulfate, calcium, and manganese concentrations
decreased by 35 to 452, nickel was reduced to below detection, and the
water became more alkaline. Lead is the only chemical which appeared
to increase during high flow, but it was only in suspended
(particulate) form.
5.4.3.2 Discussion
Storm runoff from chat covered areas contains concentrations of lead,
zinc and cadmium, but the degree of contamination appears variable and
localized. In small watersheds containing significant chat covered
areas, lead, zinc, and cadmium concentrations reached 110 ug/1, 14,000
ug/1, and 83 ug/1 respectively (Figure 5-5). The small tributaries at
083 and 084 at the southwest corner of the site had the highest lead
concentrations under high flow conditions recorded during Phase I
studies (Table 5-3).
Sample 081 was the only sample taken from a watershed draining the
area downwind of the former smelter. Although this is largely a chat
covered area, the relatively high zinc and cadmium may indicate
contributions of these metals from both chat and soils contaminated
with smelter fallout (refer to Section 4.3, Soils).
When Short Creek flow increases after a rain, most metals (both total
and dissolved forms) decrease in concentration. This decrease is due
to dilution by the relatively clean runoff water from much of the
Short Creek Watershed. However, because of the large volume of water
during high flow, the total quantity of metals (by weight) transported
downstream is actually higher than the quantity transported downstream
during low flow. These metals probably originate from chat covered
areas within the subsite, increased groundwater contribution to Short
Creek, and possibly from mining disturbed areas upstream in Missouri.
Regardless of the origin of these metals during high flow, metal con-
centrations are lower during high flow conditions and, therefore, the
impact on Short Creek water quality and the aquatic biota in the creek
is dampened by high flows.
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TABLE 5-4
EMPIRE LAKE WATER QUALITY
CHEROKEE COUNTY, GALENA SUBSITE
085 086 087 Average
Total Lead (ug/1)	7.8
Dissolved Lead (ug/1) U
Total Zinc (ug/1)	180
Dissolved Zinc (ug/1) U
Total Cadmium (ug/1) U
Dissolved Cadmium (ug/1) U
6.7
U
540
320
7.4
U
U
310
U
U
U
17.0
10.5
U
340
107
2.5
U
5.4.4.2 Discussion
Upstream of the Galena subsite influence, Spring River and Shawnee
Creek contained traces of lead and zinc, but Shoal Creek was
apparently free of mine drainage related constituents. The primary
impact of subsite drainage on Empire Lake appears to be increases in
zinc due to Short Creek draining into Spring River, and increases in
lead and zinc due to subsite drainage into Shoal Creek. The average
lead, zinc and cadmium content of Empire Lake is 10.5 ug/1, 340 ug/1
and 2.5 ug/1, respectively based on the single set of three samples.
The higher lead levels in Shoal Creek may result from the high lead
content of surface and subsurface drainage in the vicinity of 083 and
084. Lead was not present in receiving waters in dissolved form,
indicating that it is precipitating out of solution and at least some
of it is being held in suspension. This precipitation is responsible,
at least in part, for the relatively high lead content of Shoal Creek
sediments (Section 5.5.2).
5.4.5 Water Quality in Subsidence and Strip Mine Ponds
5.4.5.1 Data Sunrnary
Three surface water bodies were sampled on August 12, just before
the rainfall of August 13 and 14. All three are located within the
city limits of Galena. Water in the abandoned strip mine pit located
just northwest of downtown Galena, (069, Figure 5-6) had the highest
zinc (55,000 ug/1), cadmium (190 ug/1) and nickel (130 ug/1) con-
centrations of any surface water sample. Lead (330 ug/1) was also
relatively high. These constituents were mostly in dissolved form.
This water had a pH of 6.1, 47 mg/1 of net acidity, and contained mer-
cury at 0.33 ug/1.
The mine subsidence pond (station 068, Figure 5-6) south of the Galena
High School is known locally as the "Blue Hole." This water sample
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minimum amount of water that entered the depression because it is not
known how quickly this water infiltrates into the ground. The water
quality of tributary "A" prior to capture, based on the analysis of
sample 094, suggests that the stream runoff had undetected lead,
moderate concentrations of dissolved zinc and cadmium, and alkaline
water. The subsidence pond water quality indicates suspended lead,
zinc, and cadmium but no dissolved forms of these metals. The
periodic "flushing out" of the depression with alkaline surface waters
probably maintains the pond water in an alkaline condition and causes
dissolved metals to precipitate. This is in contrast with the strip
mine pit (069) and "Blue Hole" (068) water which is relatively
stagnant. The stream capture at 071 is probably responsible for
routing a large amount of water into the mines of the "Hell's Half
Acre" area and ultimately into Short Creek.
5.5 Sediments
5.5.1	Sediment Transport
The disturbed mine lands and chat piles on the Galena subsite are
located primarily on upland areas above the flood stages on Spring
River and Shoal Creek. However, extensive sedimentation of chat wastes
and soil/gravel eroded from the disturbed mine lands has occurred along
the flood plain in the lower reaches of Short Creek. This has placed
large amounts of mine waste in the creek bottom that are subject to
high water flow on Short Creek. Floods or high flows on Short Creek
can transport this waste into the main channel of Spring River.
Precipitation on abandoned mine lands and	chat covered areas has pro-
duced many small drainage channels filled	with sediments. Subsequent
storms transport this material onto lower	lying areas and ultimately
into Short Creek, Spring River, and Shoal	Creek.
5.5.2	Chemistry of Sediments
The mining related metals present in sediment samples which show some
trends are lead, zinc and cadmium. Figure 5-8 presents a sunmary of
test results for these metals. Lead, zinc and cadmium were highest in
the sediments of Short Creek. Shoal Creek sediments also had elevated
levels of lead, zinc and cadmium, though lower than Short Creek.
Nickel, chromium and calcium were found in Shoal Creek sediments at
levels somewhat higher than those obtained at other locations. Sample
105 in Empire Lake contained the lowest levels of lead, zinc and cad-
mium of all the sediments sampled.
The sediment samples obtained were of two distinct types: coarse-
grained sand and gravel in Short Creek, in Spring River, and upstream
on Shoal Creek; and fine-grained silts and clays in the lower reach of
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Shoal Creek and in Empire Lake. The sediments in lower Shoal Creek
also contained significant amounts of organic matter.
The high lead, zinc and cadmium concentrations of Short Creek sediments
are due primarily to the presence of mining wastes, chemical precipi-
tates, or both. The Short Creek streambed and floodplain in the area
where the samples were taken contain mine wastes and chat that were
transported to those locations by erosion. The residual ore minerals
in these materials probably account for the elevated levels of metals
in the sediment samples. Chemical precipitation of dissolved metals
from Short Creek surface water may also contribute to the high lead,
zinc and cadmium observed in sediments. Chemical precipitation may
occur most readily with lead. Dissolved lead was coming into Short
Creek via tributary "B", but was undetected in the dissolved form in
Short Creek, suggesting that chemical precipitation had occurred.
5.6	Radionuclides
Both sediment and surface water from six locations were analyzed for
radionuclides (Figures 5-1 and 5-3). The samples were analyzed for
gross alpha, gross beta, radium-226, and uranium-234, -235, and -238
(Table 5-5). The results for surface water indicate that there were no
concentrations which exceeded EPA drinking water maximum contamination
levels (EPA, 1985f) or suggested action guidelines. The results for
sediments indicate that there were no concentrations exceeding any EPA
suggested guidance level for soils. The only EPA standards which might
be used in evaluating the results for sediments are those for uranium
mill tailings sites (EPA, 1983). The results fall well below the
limits for radium set by these standards. However, the results do
suggest some impact to sediments and surface water at sample location
072, at the Kansas-Missouri state line. Farmers Chemical Company has
used phosphate rock from Florida for fertilizer production and this may
account for some of the radioactive material. In addition, the sedi-
ments sampled at 088 in Shoal Creek contained slightly elevated values
for gross alpha, gross beta, and radium.
5.7	Summary
Short Creek, the major stream draining the Galena subsite, is impacted
by chemical loading from two primary sources: mine drainage from sour-
ces within the subsite, and undetermined chemical sources upstream to
the east of the subsite. The origin of most of the mine drainage
within the subsite is two large mined areas, "Hell's Half Acre" imme-
diately north of town and the watershed for tributary "B". These areas
contribute mainly zinc and cadmium to Short Creek by surface and sub-
surface pathways. Storm runoff from chat-covered areas loads Short
Creek with zinc, cadmium and other metals, but the increased volume of
water caused by the runoff lowers metal concentrations temporarily.
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7.0 FISH INVESTIGATION
7.1	Sample Locations
Samples of game and forage fish were collected in cooperation with the
Kansas Fish and Game Commission at two areas within Empire Lake, as
shown on Figure 7-1. Samples were collected by electrically stunning
the fish and retrieving them from the water using hand nets. A total
of 34 fish were collected from Area 1, while 71 fish were collected in
Area 2. All fish collected from the two areas were identified and
counted. Six fish were retained for tissue analysis from Area 1, and
subdivided by species into two samples. Ten fish, subdivided into
three samples, were retained from Area 2. These fish were weighed and
measured and scale samples obtained for age determination. Forage
fish samples consisted of the whole fish, while game fish samples con-
sisted of edible filet portions only, with skin attached. All fish
not retained for tissue analysis were released.
7.2	Results
The species and size of fish collected are presented in Table 7-1.
Chemical analysis results are presented 1n Table 7-2.
The samples obtained had detectable levels of all metals analyzed
except antimony, beryllium, silver, and thallium. Chromium, copper,
selenium and zinc are known or suspected of being animal nutrients,
and may, therefore, be Inherent components of fish tissues (EPA,
1985c).
Forage fish (smallmouth buffalo and carp) exhibited concentrations of
all metals higher than game fish (largeraouth bass), with the exception
of mercury. Forage fish are bottom feeders and may Injest bottom
sediments containing metal 1n the course of feeding. The slight dif-
ferences between forage and game fish could be real differences or may
be a reflection of this incidental injestion of sediments since whole
body analysis was performed on the forage fish and only edible filets
of the game f1sh were analyzed.
Current results (Table 7-2) are comparable to forage fish (carp and
mixed bottom feeders) samples obtained by EPA in several Kansas loca-
tions, Including the Spring River near Baxter Springs (Table 7-3).
Analytical results for forage f1sh collected from Empire Lake are
similar to those obtained throughout Kansas for arsenic, cadmium,
chromium, copper, selenium, and zinc. Lead in forage fish was lower
1n Empire Lake samples than those collected from 1980 to 1984 In the
Spring River near Baxter Springs.
Results suggest that bloaccumulatlon of metals 1s not occurring to any
extent 1n game f1sh from Empire Lake, and the quantity of metals in
88

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forage and game fish collected in Empire Lake is similar to amounts in
forage fish collected from various locations in Kansas {EPA, 1985c).
93

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Human Exposure Assessment
This assessment outlines the potential human exposure pathways (both
direct and indirect) to site constituents. The potential migration
pathways of the constituents are defined based on the prior dis-
cussions of fate and transport and physical features of the site.
From the potential migration pathways identified, additional exposure
pathways are determined. Also, factors affecting exposure are con-
sidered.
8.5.1	Exposure Pathways
Potential exposure of humans to site constituents include:
Ingestion of or dermal contact with groundwater.
Ingestion of or dermal contact with surface water.
Ingestion of, dermal contact with, or inhalation of soils and the
finer material in chat piles and other mining related wastes.
Inhalation of constituents 1n air (airborne particulates).
Ingestion of fish and wildlife from local creeks and agricultural
or woodland areas.
Ingestion of crops irrigated with surface water or groundwater.
The direct and indirect human exposure pathways known to occur at the
Galena subslte are presented 1n more comprehensive lists in Tables 8-6
and 8-7.
8.5.2	Migration Pathways
Constituents may migrate between environmental media (i.e., ground-
water discharging to surface water), furthering the spread of these
potentially hazardous constituents. Migration pathways include:
Flow of surface water into the groundwater system through sub-
sidences, mine shafts, and porous surface materials.
Movement of soil constituents (primarily soluble) downward into
the shallow aquifer.
Erosion of mine wastes and surface soils Into creeks and ponded
waters, especially during heavy sunnier rains.
Downstream movement of soluble and insoluble constituents in sur-
face water and sediments.
112

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populations are impacted. As mentioned in Section 2.3, three
federally endangered species of salamanders inhabit the natural caves
in the vicinity of Schinmerhorn Park. These caves are downgradient of
mined areas and, therefore, could be impacted by constituents in
environmental media at the Galena subsite.
Fish tissue samples taken from Empire Lake did not differ signifi-
cantly in metals concentration from fish tissue samples taken
elsewhere in the State. Additional samples of fish and benthic inver-
tebrates from the Creeks would be useful in determining if aquatic
biota are influenced by contaminants at the site.
Impacts to vegetation are clearly demonstrated by the absence of plant
life on chat piles, mined areas, and areas Immedlaely downwind of the
former smelter at Galena. Further Impacts could occur if constituents
in soils and chat piles are allowed to spread.
8.7 Conclusions
The objective of this chapter was to address public health and
environmental concerns at the Galena subsite that may be caused by
chemical constituents associated with past mining activities and
current conditions of abandoned mined lands. The following conclu-
sions are based on the Phase I field investigations conducted during
July and August 1985.
Comparisons of contaminants 1n groundwater (private wells) to primary
drinking water standards indicated four residential wells had cadmium
concentrations exceeding the health-based maximum concentration limit
(MCL) established for this metal. Chromium in one well was the only
other metal that exceeded health-based MCLs. At the present time, U.S.
EPA considers drinking water MCLs and federally approved state water
quality standards to be the only'"applicable" or "relevant and appropriate"
ambient concentration requirements for water. In Kansas, the present
state water quality standards are similar to the federal limits. Mining
related contaminants such as cadmium, zinc, nickel, and a few other
metals were observed In some wells at concentrations above ambient water
quality criteria established for human health effects (4 of 22 wells for
cadmium, 3 of 22 for nickel, and 2 of 22 for zinc). These criteria are
based on data and scientific judgments on the relationship between the
compound concentration and human health effects (including toxic, carcinogenic,
and organoleptic effects), and are not enforceable standards.
Well water samples from several wells had concentrations of Iron,
zinc, or manganese that exceeded secondary drinking water standards.
These secondary standards are based on organoleptic properties of the
chemical and thus indicate potential taste or odor problems, but not
concerns with respect to human health effects.
119

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Surface waters within the Galena subsite are not considered as
drinking water sources (are not protected under Kansas state regula-
tions for that beneficial use), and were not compared to primary or
secondary drinking water standards, or to ambient criteria for protec-
tion of human health. Mining-related contaminants in surface waters,
however, did exceed ambient water quality criteria for protection of
aquatic life. Short Creek was the most impacted stream in the area,
with cadmium, copper, lead, and zinc concentrations exceeding acute
(short-term effects) criteria 1n 2 or more samples. Cadmium and zinc
concentrations exceeded the criteria in 14 of 15 samples from Short
Creek. Cadmium and zinc appear to be a widespread problem in the area
since in other creeks and in Empire Lake the concentrations of these
two metals exceeded criteria in 28 to 60 percent of the samples ana-
lyzed. The Phase I investigations at Galena, and prior studies by
Spruill (1984) and the Kansas Department of Health and Environment
(1980) all indicate that mining related contaminants have impacted the
aquatic biota in Short Creek near Galena.
Soil investigations during the Phase I studies at Galena were limited
to testing surface (0 to 6 inches) and subsurface (12 to 18 inches)
soils downwind of the former Galena smelter. The Phase I results
indicated that average lead, zinc, and cadmium concentrations in sur-
face soils were an order of magnitude higher than might be found in
"typical" U. S. soils. Also, the relationship between soil con-
centrations and distance from the former smelter, and the vertical
distribution of these metals, suggest that they may have originated as
airborne particulates from the smelter during the time it was
operating. One surface sample had a lead concentration that slightly
exceeded the 500 mg/kg level of concern for soils in residential areas
established by the Centers for Disease Control.
The potential exposure pathways and receptors were identified in
Tables 8-6, 8-7 and 8-8. The pathway of most concern in the Galena
area, with respect to human health effects, is the use of shallow
groundwater as a drinking water source. Exposure (or use) to surface
water and soils may be of some concern, but the degree of exposure to
these two environmental media are certainly less than that for shallow
groundwater.
With respect to impacts on animals and plants, the more immediate con-
cerns in the Galena area are the water quality degradation of Short
Creek and the localized suppression of plant growth in some abandoned
mine lands and downwind of the former smelter.
120

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Mining Waste NPL Site Summary Report
Cimarron Mining Corporation
Carrizozo, New Mexico
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) m partial fulfillment of
EPA Contract Number 68-W0-O025, Work Assignment Number 20.
A previous draft of this report was reviewed by Paul Sieminski of
EPA Region VI [(214) 655-6710], the Remedial Project Manager for
the site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
CIMARRON MINING CORPORATION SITE
CARRIZOZO, NEW MEXICO
INTRODUCTION
The Site Summary Report for the Cimarron Mining Corporation is one of a series of reports on
mining sites on the National Priorities List (NPL). The reports have been prepared to support EPA's
mining program activities. In general, these reports summarize types of environmental damages and
associated mining waste management practices at sites on (or proposed for) the NPL as of February
11, 1991 (56 Federal Register 5598). This summary report is based on information obtained from
EPA Files and reports and on a review of the summary by the EPA Region VI Remedial Project
Manager for the site, Paul Sieminski
SITE OVERVIEW
The Cimarron Mining Corporation Superfiind Site is located on 10.6 acres of privately owned land
approximately 25 mile east of Carrizozo, New Mexico, and approximately 100 miles south-southeast
of Albuquerque (see Figure 1). The milling facility was originally constructed to recover iron from
ores The facility was sold in 1979, and subsequently revamped to mill precious metals ore. The
precious metal recovery facility consisted of a conventional agitation cyanidation mill, which resulted
in the discharge of contaminated liquids and stockpiling of contaminated tailings and waste trench
sediment at the site. The mill operated without a State discharge permit, and in 1982, the State issued
a Notice of Violation (NOV) for discharging into a nonpermitted discharge pit (Reference 2, pages 1
through 3). The mill was closed in July 1982, and the owners of the facility filed for bankruptcy in
July 1983 (Reference 1, pages 1-4 and 1-5).
While conducting the Remedial Investigation at the Cimarron site, the existence of another abandoned
mill became lcnown The other location, known as Sierra Blanca, is located 1 mile south of the
Cimarron site. The two mills were owned by the same parent company (Sierra Blanca Mining and
Milling Corporation) and, for a short period, operated concurrently. File information indicates that a
possible spill at Cimarron prompted the relocation of milling operations to Sierra Blanca.
Investigation of the Sierra Blanca mill is being performed as a second Operable Unit (Reference 2,
pages 1 through 3).
Cyanide is the primary contaminant of concern; however, several metals were also identified as
contaminants of concern. Approximately 1,500 people live within 2 miles of the site (Reference 1,
1

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Cimarron Mining Corporation
380
^SITE T
LOCATION,
CARRIZOZO
RESIDENTIAL
contocr nterv*. »o feet
SOURCE uses. Gmarro* Eflit-W««t. NM J 5' CuoefcnjlM. 1SS2
NEW
MEXICO
FIGURE
SITE AREA LAND USE MAP
OUMRWCIE LOCATION
CAMP ORESSCR t ucJCCE IN'
FIGURE 1. SITE AREA LAND-USE MAP
2

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Mining Waste NPL Site Summary Report
page 2-4). The Carrizozo municipal wells are located within 2 miles of the site, and were estimated
(in 1985) to serve a population of 1,636 (Reference 3, page 7). Contaminated media of most concern
at the site are shallowground water and surface soils. The site was added to the NPL on October 4,
1989.
The Remedial Investigation/Feasibility Study was conducted between May 1989 and May 1990. In
the Record of Decision (ROD) (September 1990) EPA announced the selected remedy for the site
The selected remedy is to pump contaminated ground water from the shallow aquifer and convey it to
the Carrizozo Publicly Owned Treatment Works (POTW) for treatment, thereby eliminating the
potential for migration of contaminated shallow ground water to the deeper water-supply aquifer In
addition, source control measures would be implemented (Reference 2, page 4). Field work at the
second Operable Unit is currently underway, and it is anticipated that a Remedial Investigation/
Feasibility Study will be completed in 1991 and a ROD will be signed by the end of fiscal year 1991
OPERATING HISTORY
The mill facility was used to mill iron ores and recover iron using a magnetic separator during the
late 1960's and 1970's. Cyanide was not used in the original process, and tailings from the mill were
transported offsite and used as fill material in the Carrizozo area (Reference 1, page 1-4).
In 1979, Southwest Minerals Corporation bought the mill site and apparently began using a cyanide
process to extract precious metals from ores transported to the mill. Detailed information on the
metals extraction process operating between 1979 and 1981 was not available to EPA during its
Remedial Investigation However, cyanide was detected in an onsite discharge pit sediment sample
collected by the New Mexico Environmental Improvement Division (NMEID) in 1980, which
indicates that cyanide extraction was in operation at that time (Reference 1, page 1-4). Southwest
Minerals expanded the operation in 1981, even though it was operating without the required discharge
permit
During the Remedial Investigation, the EPA interviewed former mill employees and examined the
onsite equipment to summarize the precious metals recovery operations employed at the site after
1981 (Reference 1, page 1-5). A simplified diagram of the process is provided in Figure 2
(Reference 1, page 1-7).
Ore was transported to, and stockpiled on, the site before it was transferred to a jaw crusher for size
reduction. After the ore was crushed, it was transferred to the mill building, where it was placed in a
large hopper. Hydrated lime was added to prevent production of hydrogen cyanide gas and to
3

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Cimarron Mining Corporation
HYDRATED
LIME
ORE—v HOPPER/
\ GRIZZLY
	1

SECONDARY
ROLLER
CRUSHERS
PRIMARYl^	
JAW CRUSHER
rv
\^j
—'suwp
FEED
BIN

HE3-
BALL
MILL
RAKE
CLASSIFIER
MIXING
TANK
Ja1
lA±J
•LIME OR NoOH
-CYANIDE
• H2O
e
MIXING
TANK
FRESH CM SOLUTION
STORACE TANK
noccsi ivimi
I	ioup I	ikjuc *	tan ¦	1
F
THICKENER
solos »4
THICKENER
•3
THICKENER
•2
THICKENER
•1
EITHER/OR
TAILINGS
PILES
(I. C. OR K)
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CONVEYOR

CINDER BLOCK
TRENCHES
WASTE
PILES
IJ i u
ISM SOLOS)

a


*1 LOUD


c
:>
lU^
c
3
AGITATION
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ACIT ATION
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iRCCrciE TO
IW.L CIRCUIT)
CORE
PRODUCT

FIGURE 2. SIMPLIFIED DIAGRAM OF CIMARRON MILL CIRCUIT
4

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Mining Waste NPL Site Summary Report
optimize the cyanidation reactions. The hopper fed a ball mill and rake classifier, where cyanide
solution was added to the ore (Reference 1, pages 1-6 through 1-8).
Sodium cyanide and potassium cyanide (stored onsite in 220-pound drums) mixed with water
composed the cyanide solution. In addition, two metal-stripping chemicals, AMPREP and Enstrip 70,
(containing 15 percent potassium cyanide, less than 1 percent lead oxide, and nitro-aromatic
compounds) were apparently added to the cyanide solution to promote additional leaching of precious
metals (Reference 1, page 1-8).
The cyanide solution was mixed in two large vats, gravity fed to a large holding tank, and
subsequently pumped from this tank to the rake classifier, creating a cyanide-solution/crushed-ore
slurry. From the rake classifier, the slurry was pumped to a heated, agitated vat. Heating the slurry
promoted the reaction of cyanide with precious metals. The slurry was pumped to a second agitated
vat and then to each of four thickeners. The thickening circuit produced three distinct streams'
(1) tailings or solids; (2) fluid fraction sent for recycling; and (3) the pregnant solution. Tailings
(solids) from the last thickener in the series were pumped through a solid separator and transported to
the tailings piles by truck. The fluid fraction and small-sized solids were apparently gravity fed to the
two cement block trenches for recycling back into the cyanidation process (Reference 1, page 1-9).
The pregnant (precious metal-containing) cyanide solution was skimmed from the top of each
thickener and routed (against the direction of slurry flow) back to the second agitated vat. Pregnant
solution contained in the agitated vats was gravity fed to a large metal holding tank near the Lab
Building (Reference 1, page 1-8). Pumped from the holding tank, pregnant solution was fed through
small pressure filters to an electrowinning cell in the Lab Building. In the electrowinning cell,
precious metals were deposited onto aluminum plates. These were then heated in an outside kiln to
separate the aluminum from the precious metals and produce dor6 (Reference 1, pages 1-8 and 1-9).
The barren cyanide solution from the electrowinning operation contained free cyanide and metal-
cyanide complexes of copper, iron, nickel, cobalt, zinc, and other impurities. Most of the barren
solution was pumped to two cement block-lined trenches near the main operations building for
recycling back into the mill circuit, but a portion was discharged to the unlined discharge pit to avoid
build-up of metal impurities (which would subsequently interfere with the dissolution and precipitation
of gold in the cyanidation process). As discussed above, the fluid fraction from the thickeners, as
well as the barren solution from electrowinning was discharged into the two cement block-lined
trenches for recycling. As sediment built up in the trenches, it was removed and stockpiled onsite
(Reference 1, page 1-9)
5

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Cimarron Mining Corporation
In addition to the barren solution, backwash waste solution from the pressure filters was disposed of
in the discharge pit. Chlorine was added to the waste solution to oxidize the cyanide. Analyses of
samples from the pit indicate that this treatment was not effective. The ineffectiveness of the chlorine
treatment was possibly due to poor application methods and/or the existence of a significant quantity
of complex cyanide forms not affected by chlorine. The cement block-lined trenches and the unlined
discharge pit are the two main sources of cyanide migrating into the ground water at the site
(Reference 1, page 1-9).
The mill ceased operation in July 1982 following the June 23, 1982, receipt of a NMEID NOV for
discharging into a nonpermitted discharge pit. The State did not pursue legal action against Southwest
Minerals, and the company filed for bankruptcy in July 1983 (Reference 1, page 1-4).
SITE CHARACTERIZATION
EPA conducted a Remedial Investigation/Feasibility Study between May 1989 and May 1990 to
determine the nature and extent of contamination at the site. Prior to the site's NPL listing, several
site studies were conducted. The first investigations were performed by NMEID in February 1980,
June 1982, and May and June 1984 A site evaluation was conducted by an EPA Technical
Assistance Team in 1985, and an expanded site inspection was performed by an EPA Field
Investigation Team in 1987 (Reference 1, pages 1-4, 1-5, and 3-1).
The results of the Remedial Investigation, along with the results of previous investigations, were used
to define the sources of environmental contamination at the site. Figure 3 illustrates the location of
areas of concern at the site. EPA identified three sources of cyanide and metals contamination:
waste material (found in tailings piles and cement block lined trenches); cyanide solution and tailings
spillage areas (around milling facilities); and cyanide solution recycling and disposal areas (cement
block-lined trenches and discharge pit). Onsite tanks and drums hold materials contaminated with
cyanide and heavy metals. During the Remedial Investigation in June 1990, EPA determined that
these materials were contained, and were not a source of environmental contamination (Reference 1,
page 5-15)
Surface soils and waste piles, tank sediments, air, and shallow ground water were identified as
potential exposure risks at the Cimarron site. The Remedial Investigation identified contaminants of
concern including cyanide, arsenic, barium, chromium, copper, lead, manganese, mercury, nickel,
nitrate, selenium, vanadium, and zinc (Reference 1, pages 5-1, 5-2, and 7-41 through 7-46).
Sampling was conducted both onsite and offsite.
6

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Mining Waste NPL Site Summary Report



i
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Cimarron Mining Corporation
Ground Water
The Remedial Investigation delineated two geologic units at the site: northwest-dipping Cretaceous
interbedded shale, siltstone, and sandstone; and an overlying unsaturated alluvium. The water-
yielding units of the bedrock were determined during the Remedial Investigation to be thin, apparently
discontinuous sandstones and siltstones interbedded with thick shales. Slug tests indicated variable but
low permeabilities across the site. Water levels in two adjacent wells screened in separate
stratigraphic units indicate a strong downward ground-water gradient at the site (Reference 1, pages
2-8 through 2-11).
Cyanide was found in several monitoring wells across the site as a result of the Remedial
Investigation ground-water sampling conducted in November 1989. Total cyanide concentrations
ranged from 10 to greater than 4,000 parts per billion. The ground-water contamination occurs in
discontinuous, permeable Cretaceous sandstone units situated within thick, low permeability shales It
is estimated that contaminated ground water is present in two sandstone units. Due to the strong
downward ground-water gradient, the Remedial Investigation suggests that ground water either flows
downdip in these units or downward through fractures and joints until another permeable unit is
encountered. No cyanide contamination has been observed in the deep monitoring well; however,
low levels of cyanide were found in the deep abandoned onsite supply well. According to the
Remedial Investigation, it is suspected that this contamination resulted from the cross-connection
between upper and lower zones created by this well. No cyanide was detected in the domestic wells
upgradient and downgradient of the site, which were sampled during the Remedial Investigation
(Reference 1, pages 5-7 through 5-11, 2-19, and 2-26).
The Remedial Investigation determined that the major sources of cyanide contamination of the ground
water are the cinder block trenches, and to a lesser degree, the discharge pit. Cyanide-contaminated
soils underlying the tailings piles identified this area as a potential, though minor, source. During
operation of the plant, concentrated cyanide solution (about 100 milligrams per liter) was stored in
cracked and leaky cement block-lined trenches for recycling. Waste cyanide solutions were also
disposed of in the unlined discharge pit. The Remedial Investigation determined that most of the
cyanide ground-water contamination occurred during the period of plant operation through probable
continued discharge of cyanide solution. The discharge of cyanide solution in the concrete block
trenches and the unlined discharge pit was terminated in 1982, when the mill was closed.
The application of a model to the ground-water cyanide contamination indicated that transport of
cyanide contamination to the ground water since the plant closing is negligible due to the discontinued
cyanide source, insufficient hydraulic head to induce recharge, dilution, and biodegradation.
8

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Mining Waste NPL Site Summary Report
However, precipitation events may increase the potential for migration of contaminants from soils to
ground water (Reference 1, pages 5-2 and 5-3).
Areas of elevated concentrations of metals in the ground water occur in areas distinct from cyanide-
contaminated ground water, according to sampling conducted in 1989. Elevated metals concentrations
are present in the ground water surrounding the trenches and discharge pit; however, the area of the
site most effected by elevated metals concentrations in ground water is below and downgradient of the
tailings disposal area It is presumed that as additional slurry was placed on top of existing piles,
liquid from the slurry leached metals, salts, and other constituents from the tailings material.
Chromium [0.07 to 2.4 parts per million (ppm)], lead (0.12 to 1.5 ppm), iron (93.1 to 977.0 ppm),
manganese (0.111 to 2.13 ppm), and selenium (0.014 to 0.046 ppm) are at concentrations exceeding
State and Federal ground-water and drinking-water standards (Reference 1, pages 5-11 and 5-12).
Soils
Cyanide-contaminated soils are found in tailings piles; sediment piles; the discharge pit and trenches;
and tank-sediment and surface-spillage areas surrounding the mill and lab areas. The highest surface
soil concentrations of cyanide are found in the discharge pit (46.5 ppm) and the area surrounding the
cement block-lined trenches (20 4 ppm). Total cyanide concentration in soils decrease with depth.
No soil cyanide contamination was detected below 5 feet, with the exception of the discharge pit
(Reference 1, page 5-4).
Metals contamination of surface and subsurface soils is primarily confined to the surface and near-
surface soils in the cyanide contaminated areas. Iron (maximum concentration 151,000 ppm), cobalt
(maximum concentration 113 ppm) and copper (maximum concentration 470 ppm) are consistently
present in concentrations greater than background. Arsenic, barium, beryllium, calcium, chromium,
manganese, mercury, nickel, sodium, vanadium, zinc, and lead are elevated to a lesser degree
(Reference 1, pages 5-5, 4-19, and 4-20)
Air
Air sampling conducted during the Remedial Investigation detected low levels of cyanide. The
highest observed total cyanide concentration was 30 micrograms per cubic meter during a 4-hour
sampling period (Reference 1, page 5-6).
9

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Cimarron Mining Corporation
ENVIRONMENTAL DAMAGES AND RISKS
Site contamination was revealed in the analyses of soil samples collected during a 1980 NMEID Field
Inspection. This initial sampling revealed the presence of cyanide and elevated metals in shallow
ground water, soil, and mill tailings (Reference 1, page 1-4). Additional investigations, including the
Remedial Investigation/Feasibility Study, delineated the extent of cyanide and metals contamination at
the Cimarron site.
The June 1990 Remedial Investigation Report presents an Endangerment Assessment showing the
potential human health risks associated with the existing conditions for the site. Land surrounding the
site is used for agricultural, commercial, recreational, and residential purposes. The Remedial
Investigation estimated a total population of 1,500 within a 2-mile radius of the site (Reference 1,
pages 2-3 and 2-4). The main mill facility is fenced to prevent access (including the tailings disposal
area). The Risk Assessment identifies cyanide as the primary contaminant of concern and several
metals as additional contaminants of concern (Reference 1, pages 7-41 through 7-46).
The Risk Assessment determined that, under a current exposure (offsite resident) scenario, it is
unlikely for human receptors to experience adverse noncarcinogenic health effects. The highest
excess cancer risk for exposure resulting from site visits or inhalation of fugitive dust in Carrizozo is
4.7 x 10"8 (Reference 1, pages 7-78 through 7-83).
The Risk Assessment also determined that, under a future exposure (onsite resident) scenario, there
may be concern for potential noncarcinogenic health effects in children or adults ingesting
contaminated ground water The highest excess cancer risk is 8.7 x 10"6 (resulting from incidental
ingestion of soils) (Reference 1, pages 7-78 through 7-83).
REMEDIAL ACTIONS AND COSTS
As determined in the Endangerment Assessment, contaminated soils, sediment, and waste piles do not
require remedial action, since concentrations are not above health-based levels. The remedy for the
site would remediate contaminated shallow ground water that may migrate to underlying drinking-
water aquifers. Additionally, a source-control remedy to address the major sources of contaminants,
the cinder block trenches and the discharge pit, was proposed to prevent the further release of
contaminants to ground water (Reference 1, page 10-1). The ground water remedy consists of:
•	Installation of extraction wells and below-grade pumps.
•	Pumping of the extraction wells for an estimated 13 months.
10

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Mining Waste NPL Site Summary Report
•	Installation of discharge piping to convey contaminated ground water from the pumping wells
to a sewer tap. The sewer would convey contaminated ground water to the Carrizozo POTW
•	Continued monitoring of ground water for 30 years.
The estimated capital costs for the ground-water remedial action are $43,700, and the system
operating costs are estimated at $18,000 (based on 13 months of operation). Operating and
maintenance costs associated with 30-year monitoring of ground water are estimated at $32,025. The
total estimated present worth cost for the ground-water remedial action is $94,525 (Reference 1,
pages 11-20 through 11-27; Reference 2, Declaration, pages 64 through 67).
In addition to the ground-water remedy, three other preventive measures were proposed. These
additional remedial activities would ensure that onsite precipitation runoff would not collect and
infiltrate to the ground water. The source-reduction remedy consists of:
•	Removal of process chemical drums and tanks
•	Backfilling of the discharge pit and cement block-lined trenches with onsite soils and waste pile
materials and covering with clean soil
•	Plugging of the onsite abandoned water supply well (Reference 1, page 11-5; Reference 4).
The estimated cost for filling the cement block-lined trenches and discharge pit are estimated at
$10,000 (Reference I, page 11-5).
CURRENT STATUS
A ROD for the Cimarron Site (Operable Unit 1) was completed and signed by the Regional
Administrator for EPA Region VI in September 1990 (Reference 2). According to Region VI, EPA
is currently waiting for an enforcement moratorium to expire before designing the necessary remedial
actions. Environmental problems at a second location, Sierra Blanca, were found during the
Remedial Investigation of the Cimarron site. Sierra Blanca is now being treated as a separate
Operable Unit. Field work is underway at the site; it is anticipated that a draft Remedial
Investigation/Feasibility Study will be completed in May 1991, and a ROD will be signed by the
Regional Administrator in September 1991.
11

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Cimarron Mining Corporation
REFERENCES
L. Remedial Investigation/Feasibility Study Report, Cimarron Mining Corporation Site; EPA; June
15, 1990.
2 Record of Decision, Cimarron Mining Corporation Site: Operable Unit 1 - Decision Summary;
EPA; September 1990.
3.	Hazard Ranking System Score Sheet and Documentation for the Cimarron Mining Corporation;
R Lowey, R Rawlings, and S. Cary, EPA; November 26, 1985.
4.	Fact Sheet, EPA's Preferred Remedy for the Cimarron Mining Site; EPA Region VI; July 1990.
12

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Mining Waste NPL Site Summary Report
BIBLIOGRAPHY
EPA. Record of Decision, Cimarron Mining Corporation Site: Operable Unit 1 - Decision
Summary. September 1990
EPA Remedial Investigation/Feasibility Study Report for Remedial Investigation/Feasibility
Study-Related Activities at the Cimarron Mining Corporation Site, Carrizozo, New Mexico,
Volumes 1 and 2 of 5. June 15, 1990.
EPA Region VI. Fact Sheet, EPA's Preferred Remedy for the Cimarron Mining Site. July 1990
Lowey, R , R Rawlings, and S. Cary (EPA). Hazard Ranking System Score Sheet and
Documentation for the Cimarron Mining Corporation. November 26, 1985.
Sieminski, Paul (EPA). Personal Communication Concerning Cimarron Mining Corporation to Mary
Wolfe, SAIC. August 14, 1990.
Sieminski, Paul (EPA). Personal Communication Concerning Cimarron Mining Corporation to Mark
Pfefferle, SAIC January 28, 1991
13

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Cimarron Mining Corporation
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From Remedial Investigation/Feasibility Study Report,
Cimarron Mining Corporation Site;
EPA; June 15, 1990

-------
REMEDIAL PLANNING ACTIVITIES AT
SELECTED UNCONTROLLED HAZARDOUS
SUBSTANCES DISPOSAL SITES IN A ZONE
FOR EPA REGIONS VI, VII, & Villi
mwdim. wvEsnanoN/nAsiemiY stud* m
FOR
Ri/?s and related activities
AT 1HE
CIMARRON MINING CORPORATION SITE
CARRIZOZO, NEW MEXICO
VOLUME 1 or S
CONTRACT NO. 68-W9-0021
CDM Federal Programs Corporation
	Camp Dresser McKee, Inc.

-------
In consideration of these pathways, the RI/F5 provides data for charac-
terizing the off-site movement of contaminants so as to allow selection of
a permanent and cost-effective remedy that avoids or reduces risk to
acceptable levels and addresses ARARs.
1.2 SITE DESCRIPTION AND HISTORY
The Cimarron Mining Corporation site is an inactive milling facility
originally owned by Zia Steel Inc., and used to recover iron from ores
transported to the site. The iron recovery process took place between the
late 1960's and 1979 (Bottenelli, 1989) and involved crushing of the ore,
formation of a pumpable slurry by mixing with fresh and recycled water, and
collection of the ferric (iron) portion using a magnetic separator.
Cyanide was not used in this original process, and tailings were trans-
ported from the site and used as fill material in various locations in the
Carrizozo area (Neiderstadt, 1989). In 1979 the site was sold to Southwest
Minerals Corporation, which apparently began using cyanide soon thereafter.
Cyanide was used to extract precious metals from ore. Details on the oper-
ation between 1979 and 1981 are not available other than a 1980 New Mexico
Environmental Improvement Division (NHEID) sample analysis report, which,
as discussed in Section 3.1, noted the presence of cyanide contamination.
Southwest Minerals, a subsidiary of the Sierra Blanca Mining and Milling
Company, operated without the required permits necessary far conducting
cyanide processing at the site. In mid-1981, the operation was expanded by
adding several large mixing tanks, cyanide solution tanks, thickeners, and
associated pumping and conveying equipment. NHEID sent a certified notice
of violations to Cimarron Mining Corporation on June 22, 1982 for discharg-
ing into a non-permitted discharge pit; and, m July 1982, the facility
ceased operation. No legal action was taken by the State, and the company
filed for bankruptcy m July 1983.
NMEID field inspections of the site m February 1980, June 1982, and in May
and June 1984 revealed the presence of cyanide and elevated metals in
shallow groundwater, soil and mill tailings.
1-4

-------
An Expanded Site Inspection (ESI) was conducted from January to October,
1987 by an EPA Field Investigation Team lFIT) (Ecology and Environment,
1988). The objective of the ESI was to collect additional data for the
Hazard .Ranking System (HRS) process, and to facilitate RI/FS planning. A
surveyor was contracted to produce a topographic base map indicating
locations and elevations of on-site features. The site map is presented as
Figure 1-2.
On-site activities performed during the ESI included surface and subsurface
soil sampling, visual inspection of process tanks, sampling of remnant
materials in the tanks, quantifying waste volumes, sampling and geologi-
cally describing subsurface soil borings during installation of monitor
wells, sampling groundwater in the monitor wells and in nearby water supply
wells, testing m-situ permeability at the monitor wells, and identifying
adjacent land uses.
All of the samples were collected on-site, with the exception of one back-
ground soil sanple and water samples from off-site water-supply wells. A
sumnary of the ESI findings is provided in Section 3.3.
Based on the findings of the previous site investigations, and the prepara-
tion of the HRS package, the Cimarron Mining Corporation site was proposed
for addition to the National Priority List (NPL) on June 24, 19B8. On
October 4, 1989, the listing was promulgated.
1.3 SUMMARY OF MILLING PROCESS
This section sunmanzes the site mineral recovery operations as determined
by examination of on-site equipment and discussions with former employees
of the null. The process is summarized in the flow sheet presented as
Figure 1-3, and the location of the various components is shown in Figure
1-2.
Ore was transported to the site via public highways, and stockpiled on
site. The broken ore was hauled up a ramp and fed into a jaw crusher which
fed a series of conveyor belts. Ore from the jaw crusher was classified,
1-5

-------
i
) \	•» MC I I Mt '
'.3f/SBr	." ¦
yaw
Ca loU/IO^B
/.'
\ 1
V-*M /'	* "	' )- j U
Tf/5!yp&i_./ ^ 4^'^ /
/ < '*
It
itrvAitons smuwn am 'to ASQwt a«oo rt msl
CIMARRON MININC CORl'OHATlUM
CARR»ZO?0 Ml W Ml SIH * McfcIC tHC
MARCH 1090 I IIGURI I 2

-------
LKJUO
HYORATED
LIME
0RE HOPPER/
\ GRIZZLY
^3?
SECONDARY
ROLLER
CRUSHERS
PRIMARYl
£
—^UMP
OVtRSlJE
JAW CRUSHER
FEED
BIN
HDZ3-
BALL
MILL
RAKE
CLASSIFIER
MIXING
TANK
fll (dT
-LIME OR NaOH
CYANIDE
* H2O
MIXING
TANK
FRESH CN SOLUTION
STORAGE TANK

THICKENER
SOLOS	*4
THICKENER
~3
EITHER/OR
G
THICKENER
•2
IK*®
THICKENER
•1
TAILINGS
PILES
(I. C. OR K>
HYDROCYCLONE/
CONVEYOR
m
LK»M>
LIOUD
CINDER BLOCK
TRENCHES
WASTE
PILES
(J t L)
(SMC SOLAS!
\
PROCESS SLURRY
1 Ktun
siupnr
AGITATION
VAT *2
AGITATION
VAT •!
LIOUD
»	FILTRATION
' 5?
	Si-	
DORE
COLD FURNACE
PLATES
PREGNANT LIQUOR,
HOLDING TANK
n
FIGURE 1-3
SIMPLIFIED DIAGRAM OF THE
CIMARRON MILL CIRCUIT
-P'D'ri'
ELECTR0WINN1NG
CELL
DISCHARGE PIT
(RECYCLE TO
MILL CIRCUIT)
LKJUO
OORE
PRODUCT
CAMP p' ~ER t McKEE INCi

-------
and the oversized ore was directed through a secondary crushing circuit
which consisted of a roll (or drum) crusher. The crushed ore was then sent
to a large hopper located in the mill building. At this point, hydrated
lime was added to maintain a high pH to prevent production of hydrogen
cyanide gas and to optimize the cyanidation reactions. The hopper fed a
ball null which fed a rake classifier. Oversized material from the rake
classifier was sent back to the ball mill and cyanide solution was added at
that point.
The cyanide solution apparently consisted primarily of sodium cyanide
[NaCN) and potassium cyanide (KCN] (stored on the site in 220 pound drums),
water and recycled cyanide solution. Metal stripping chemicals (AMPREP and
Enstrip 70) were also apparently used with the cyanide to promote addi-
tional leaching of precious metals. The Material Safety Data Sheets (MSDS)
for the strippers, and discussions with the manufacturer, suggest that they
contain 15% potassium cyanide, <1% lead oxide, and nitro-aromatic
compounds.
The cyanide solution was mixed on the second floor of the main operations
building in two large vats which gravity fed a large holding tank on the
bottom floor. Solution was pumped from this tank to the rake classifier,
creating a cyanide-solution/crushed-ore slurry. After passing through the
rake classifier, the slurry was pumped to a pair of agitated vats, and then
to a series of four thickeners. The first agitated vat was heated using
propane gas to promote the reaction of the cyanide with precious metals.
Slurry was pumped in succession from the first agitated vat to the second
agitated vat, and then to each of the four thickeners. Pregnant (precious
metal containing) cyanide solution was collected from the top of each
thickener and routed counter current to the direction of slurry flow, back
to the second agitated vat (Figure 1-3). The pregnant solution was gravity
fed from the agitated vat to a large metal holding tank (pregnant solution
tank) near the lab building.
The "pregnant" solution was pumped from the holding tank through a series
of small pressure filters to an electrowinning cell in the lab building.
Precious metals were electrowon (deposited) onto aluminum plates, which
1-8

-------
were heated in a crude kiln located outside the lab. Precious metals were
separated from the aluminum and dor# (unrefined product) was produced. The
lab also contained various analytical equipment; including a fire assay
furnace, an atomic absorption unit, and an analytical balance for deter-
mining precious metal values.
The "gold free" barren cyanide solution, from the electrowinning process
contains free cyanide and metal-cyanide complexes of copper, iron, nickel,
cobalt and zinc, as well as other impurities (Huiatt, et al., 1983). Much
of the barren cyanide solution was pumped to the two cinder block trenches
near the main operations building for recycling back into the'mill circuit,
but a portion was discharged to the discharge pit so as to avoid build-up
of metal impurities which would subsequently interfere with the dissolution
and precipitation of gold in the cyanidation process. The cinder block
trenches used for recycling the barren cyanide solution are not water-
tight, and served as an avenue for percolation of contaminated solution
into the underlying soil and groundwater. Backwash waste solution from the
pressure filters at the pregnant solution tank was disposed to the dis-
charge pit, where it evaporated and percolated into the ground. Chlorine
was added to the waste solution so as to oxidize the cyanide (Ellison,
1989); however, that treatment w2s not effective, as analysis of soil
samples from the pit are contaminated with cyanide. The ineffectiveness of
the chlorine treatment could have been due to poor application methods, the
existence of a significant quantity of complexed cyanide forms not affected
by chlorine, or both. As discussed further in this report, the cinder
block trenches and, to a lesser degree, the discharge pit are the two main
sources of cyanide contamination of groundwater at the site.
Solids were pumped from the last thickener through a solid separator
Ihydrocyclone or simple sand separator) and were conveyed and discharged to
a truck for transport to the tailings piles (Piles I, C & K, Figure 1-2).
The fluid fraction (and small sized solids) were apparently gravity fed to
the two cinder block trenches for recycling back into the process.
Sediments which would build-up in the trenches were removed and stockpiled
on-site. Pile L and the western-most J Pile are apparently comprised of
that sediment.
1-9

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380
RANGELAND
RANGELAND
RESIDENTIAL
'-SITE /
LOCATION
CARRIZOZO
RECREATIONAL
RESIDENTIAL
ClTr LIMITS
CONTOUR INTERVAL 100 FEET
SOURCE USCS. Cimarron East-*«st. MM 7.5' Qwaarangios, 1982
N
FIGURE 2-1
SITE AREA LAND USE MAP
0 COO 1000
NEW
MEXICO
quadrangle LOCATION
Firr
CAMP DRESSER I mcKEE inC
2-3

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beyond. The recreation facilities consist of a golf course, a little
league field, a playground and picnic area. Railroad tracks and Highwav
lie west of the site. One residence and a convenience store are loca.,./
near the intersection of hihgways 54 and 380.
Based on a 1982 U.S. Geological Survey Topographic map of the area, 1 :o
people reside within a one-mile radius of the site and about 1,500 reside
within a two-mile radius of the site (NMEID, 1989). The closest inhabited,
residence in Carrizozo is approximately 1/4-mile south of the site. The
main population center of Carrizozo is approximately 3/4-nule from the
site. Census data for the region indicate that the population of Carrizozo
is relatively stable, with less than five percent increase in population
between 1970 and 1988 (Shore, 1990).
2.4 GEOLOGY
This section discusses the regional and site specific geology for the
Cimarron site area. The regional geology section is based upon available
literature and geologic maps. The site specific geology was determined as
part of the RI. Continuous core samples were collected and described by a
CDM geologist during the field investigation and geophysical logging
conducted in one deep borehole. The borehole logs and the geophysical lu^a'
are presented in Appendices A and B, respectively.
2.4.1 REGIONAL GEOLOGY
The Cimarron Mining Company site is situated near the axis of the northern
portion of the Tularosa Basin. This basin forms an elongated valley that
extends more than 200 miles from the vicinity of Carrizozo, New Mexico,
southward into Chihuahua, Mexico (Cooper, 1965).
2.4.1.1. Regional Stratigraphy
The northern portion of the basin, in the vicinity of Carrizozo, consists*
of Quaternary age alluvial and material underlain by Tertiary to Permian
age roclcs. Figure 2-2 illustrates the surface exposures of these deposits.
A stratigraphic column is shown as Figure 2-3.
2-4

-------
of alluvial material. The resulting topography is characterized by gently
sloping alluvial plains with little relief. Localized hilly regions, such
as Willow Hill and the Cub Mountains south of Camzozo, result from
outcrops of more resistant rocks.
2.4.2 SITE GEOLOGY
The following description of site geology is based upon the results of the
RI field investigation in which eight monitor wells were installed and
three additional boreholes were drilled. The boreholes and monitor wells
were continuously sampled, where possible, during drilling. The borehole
logs and geophysical logs are included in Appendices A and B, respectively.
2.4,2.1 Site Stratigraphy
The stratigraphy at the site consists of two principal units. The
uppermost unit is characterized by a fine grained alluvium consisting of
brown to tan calcareous, sulfate-rich silty clays and clayey sands. This
unit which is present to depths of 16 to 27 feet was found to be unsatur-
ated in the vicinity of the site. The lower unit, extending to a depth of
at least 200 feet consists of interbedded shales and fine-grained sand-
stones and siltstones. These more indurated rocks were observed to be
fractured and pointed to a depth of at least 70 feet below the surface.
Most of the fractures and ]oints appeared to be sealed by iron precipi-
tates. This unit can be divided into subunits which may be used for local
correlation at the site, but do not appear to be continuous over larger
areas. Based upon the available literature and the geologic map of the
area, this unit appears to be part of the Cretaceous Mesa Verde Group. A
study done for a potential mining site approximately two miles to the north
also indicated that the Cretaceous sediments below the alluvium belonged to
the Mesa Verde Group (Shomaker, 1979, 1984).
Two geologic cross-sections, as located in Figure 2-4 have been developed
from information gathered during the RI. Figure 2-5 is a southeast to
northwest cross-section which shows the Quaternary alluvium overlying the
dipping Cretaceous beds. As shown in this figure, the individual units
2-8

-------
A
LJCtKO
CNOii UXIHX iUCAltON
UONflON *Lt 1 iOOTium
SO Ni rt' Ml xn o
i • i
CROSS-SECTION
LOCATION MAP
UARCll 1990

-------
K»
I
llil (MSI )
L>no ,
III l |w i |
'j4H<)
b46()
b440
5420
5400
t)3B0
M60
.1 D?
MW I I
MW 1J
AllU«IUfT»
I lent*
1111
A'
MW I
Huei/OK'At sc*i« Ai *atM
vt MliCA4	I >Oa
MOII •All* (IVtiS UOSuKf J (»•
MW t 1
loloi d«pih at !i?68
Sc«««ne4 lo<«rvoi liom t> 11 » io Si?»
All shot* ond cotbonoc0ou» shot* ,
• •ctpl (a* sondatone* ol ±>3<0 bi«l
SJIO 53li
t> JO 4 b W6
Walei level mMluiemenl loktn on l/llj/'JO «qs iJ69 60
I >.1 i.
( IMAHHOH MlliitU. filtv. <.iw* .<
f AKHI 'OU 11| i i| h (\
GEOLOGIC
CROSS-SECTION A-A'
kiKHi n l*i
jh ~r t h I 'HI '

-------
within the Cretaceous sediments are generally discontinuous in the direc-
tion of the dip over most of the site. Figure 2-6 is a south to north
cross-section which shows that some of the units may be laterally contin-
uous across the site in a direction perpendicular to the dip of the Creta-
ceous units.
2.4.2.2	Site Structure
Observations of the recovered core material and the geologic cross-sections
developed from the CDM borehole logs indicates that the Cretaceous beds are
dipping to the northwest across the site at approximately three degrees.
There may be an additional structure between wells MW-12 and MW-16 (Figure
2-6). The units in fW-16 which appear to correlate to units in MW-12, are
structurally higher than expected. There are not enough data to define the
nature of the structure.
2.4.2.3	Sit Topography
The ground surface is unpaved and slopes down to the northwest across the
site. Figure 2-7 illustrates the topography and the noted drainage
patterns across the site. The abandoned railroad spur on the north end of
the site provides a drainage pathway along the northern boundary of the
site, sloping down to the northwest. The northwest portion of the site is
sloped from the main milling area to the railroad spur drainage near the
northwest corner of the security fence. A drainage pathway is also present
on the south side of the site, sloping to the west, bending i.jrth along the
western boundary of the site, and converging with the drainage from the
main milling area near the northwest corner of the site. Surface drainage
also flows from the tailings area on the east side of the site into the
railroad spur drainage on the northeast end of the site which eventually
converges with the rest of the site drainage pathways at the northwest
corner of the site.
water was observed to flow across the surface along the indicated pathways
during two separate storm events which occurred during the RI field invest-
igation. The overall slope is approximately 1.1° to the northwest but may
2-11

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RW-7
RW
SITE
LOCATION
RW-9
RW-4
CARRIZOZO
RW-1
RW-6
RW-5
CITY LIMITS
RW-2^^RW-3
CITY OF CARRIZOZO
MUNICIPAL SUPPLY WELLS
N
9 «00 1000
FIGURE 2-9
RESIDENTIAL WELL
SAMPLING LOCATIONS
LEGEND
WELL LOCATION
• SPRING LOCATION
NOTE: WELL LOCATIONS
ARE APPROXIMATE
nrr
CONTOUR INTERVAL 100 CEET
NEW
MEXICO
OUAORANGLE LOCATION
:amP DRESSER I mcKEE INC«
2-19

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of the model application indicate that infiltration of precipitation to the
shallow groundwater unit at the site does occur, but on a limited basis.
Using climatic data from the time period of 1969 through 1988, the model
application predicts infiltration of 16.261 of total precipitation. Con-
sidering the and climate of the area (12.46 inches/year precipitation for
measurement period), the total volume of precipitation that infiltrates per
year to the shallow groundwater at the major source area (approximately 500
ft2) of the site (cinder block trenches) is approximately 84 cubic feet, or
631 gallons. The remaining precipitation is absorbed by the surface and
near surface soils at the site and subsequently lost through evapotrans-
piration.
The HELP Model application did not, however, consider collection of runoff
water. The cinder block trenches and the discharge pit act to -collect
stormwater runoff from their surrounding areas. This increases the poten-
tial for greater onsite infiltration of precipitation to the groundwater
during and after storm events. As discussed in Section 11.4, however, this
potential migration route could be addressed by filling in and grading
those locations.
Groundwater at the site is found only in the sedimentary rocks. The allu-
vium was not observed to be saturated. The groundwater is present under
water-table conditions at depths ranging from 21 to 42 feet. The water
yielding units are thin, apparently discontinuous sandstone and siltstone
beds intecbedded with thick shales. As discussed in Sections 4.2.13 and
4.2.14, slug tests were performed on five of the eight monitor wells
installed in the Rl. The slug tests indicated variable but low permeabil-
ity across the site. The hydraulic conductivity varied from 2.8 ft/day (1
x 10"3 cav/sec) in well MW-10 to 5.7 x 10"1 ft/day (2.0 * 10"s cm/sec) in
well MW-16. The yield of all wells installed at the site is low (approxi-
mately two gallons per minute or less).
2.5.2.2 Site Groundwater Flow
The water level in wells MW-1 through MW-10 and MW-12 through MW-17 indi-
cates a gradient to the northwest. Elevations are posted on Figure 2-12
for the water levels measured at the site wells. These water levels
2-24

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*
MB I'
15 M
//
»¦
h
KH tS
79 09
S
%
u
/
tin
O (J
MM-14
J0.M
«!•«
700
~
~ mix
*
\
I,.	V
(
MC J I SIC 1
I « s
MOlf tltVAHONS SHOWN APC »IO ABOVt S4O0 n USL
MW U WAIFR IfVll MCASURlMfNl IAKIN 01/10/90
A^iO lb SHOWX in Ftn ABCVf USL
A*/

cmuNO watt* MONnoAiMC win
VOCATION «M0 OCStGHAnOH
ON MATTR li\Al UCASuAtUfNI |AM(N 10 AW
CIMARRON MINING CORt'CIKAliON
CARRIZOZO. mw Ml XII O
WATER TABLE MAP
OCTOBER 26. 1989
( AMP HKISjH A	INf
MARCH 1990 1 IIGKRl ?-t 1

-------
coincide with the top of the saturated zones of individual water bearing
units. A potentiometric contour map is not presented because the wells on
the site are screened in different stratigraphic units as shown on Figure
2-5.
The water levels in adjacent wells MW-10 ard mw-11 which are screened in
separate stratigraphic units show a strong downward gradient exists at the
site. The static level elevations measured in m-lQ and MW-11 on 1/10/90
were 5,432.82 and 5,389.80 feet respectively. There are approximately 111
feet of sediment between the two sandstone units in which these wells are
screened. The downward gradient in the area of MW-10 and MW-11 is 0.38
ft/ft. This suggests that groundwater within the individual sandstones and
siltstones at the site flows in the downdip direction of the units, when
the individual units pinch out against adjacent and underlying shales, the
water will either seek to move laterally until it finds another permeable
strata, or it may move downward through open fractures and joints until
another permeable unit is encountered. In general, most of the fractures
and joints observed .during the RI field investigation appeared to be sealed
by iron precipitates; however, there may still be enough open fractures to
allow some downward migration of groundwater through the shale units. It
should be noted that no cyanide contamination has been observed in the deep
monitor well MW-11, which is located below the area of the site where the
shallow groundwater is most contaminated with cyanide.
2.5.2.3 Site Groundwater Use
There is one water well on the site which was installed to supply water for
the gold extraction process and is no longer in use. No reliable well
completion records were found for the well. It is at least 126 feet deep.
The screen interval is not known. The well was installed by Wesley Weehunt
Drilling and Pump Service based in Tularosa, New Mexico. This water well
is located in the southeast corner of the site, upgradient of the most
contaminated area of the site discussed in Section 5.2.1, but is in an area
where some low level cyanide contamination is present in the shallow zone.
As discussed in Section 5.2.4, some cross contamination of water units has
2-26

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3.0 PREVIOUS INVESTIGATIONS
The first documented investigations of the Cimarron site were performed by
the New Mexico Environmental Improvement Division (NMEID) in February 1980,
June 1982, and Play and June 1984. On June 28, 1985, an EPA Technical
Assistance Team (TAT) conducted a site evaluation (U.S. EPA, August 1985),
and in 1987, an EPA Field Investigation Team (FIT) performed an Expanded
Site Inspection (ESI). The ESI started on January 17, 1987, and field
activities were completed October 31, 1987 (Ecology and Environment, 1988).
3.1 NMEID INVESTIGATIONS
NMEID performed a field inspection of the site in February 1980. Sediment
samples were collected from the bottom of the discharge pit. As shown in
Table 3-1, total cyanide was present in the sediment in concentrations
ranging from 12.7 to 81.2 mg/kg. Mercury was also present in concentra-
tions ranging from 6.7 to 99.2 mgAg. Mercury was found only in very low
concentrations during following investigations. In fact, mercury was not
detected in discharge pit samples collected during the RI field
investigation (Section 4.2). Since mercury was also not elevated in site
groundwater (Section 4.2), it is surmised that mercury was lost from this
contaminated material by volatilization.
On June 6, 1982, NMEID collected process solution samples from the dis-
charge pit and from the cinder block trenches used as recycle solution
holding tanks. As shown in Table 3-2, total cyanide was present in high
concentrations (72 to 116 mg/L).
The above samples were collected while the mill was operating, and based on
the null operating procedure it is concluded that the solution in the
cinder block trenches was barren cyanide solution, from the electrowinning
process and decanted from tailings, to be recycled back to the front end of
the mill process (Figure 1-3). The solution in the discharge pit probably
consisted of waste barren cyanide solution from the electrovinning process,
and possibly backwash wastewater from the pressure filters between the
pregnant solution tank and the electrowinning unit. The presence of these
3-1

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TAB LA. 4-6
SliPOIXAV OF SlfRFACE SOIL SAMJ'IXS WITII HLTKLS
com.LNTRATIONS MM)VI bALKl*RUUNU LLVtUb
I OH/69 >
Aistnic	B«i iu»	Baiylkiu*	C«Uiua	ihionui	Cob«lt	Coppec	I i on	u4j
S4^>l« ID	| | R	||	B	||	R	II	R	t I «	II	R	||	R	||	|<	| | R
I
H
M3
ound
Softt ft»*n
hi-004
HI-OOS
HI -00 7
HI'009
m-oio
hi 311
moil
HI 014
HI 016
HI 018
»P
OP
Hi'001
H2Q02
H2-00)
Hi-004
M2 00S
Hi-006
Hi -008
Hi-009
ni-010
Hi-011
Hi-Oli
Hi-Oil
fW- 10-0-0 V
5L-002-0-0 S'
SL-001-0-0 S
SL-004-0-0 S
2 s
no 3
1
0
0
66
1 0
28.771
I 0
8
0
1 0
;
9
1 0
19
4
1
0
22
2IA
i 0
1 h
1
ill
1
8
0
94
1 4
S6.000
1 9
9
1
1 1
19
9
2 S
SA
0
2
9
49
>00
2 2
1 8
4

<1

1
»
2 o
S4 100
1 9
11
7
1 b
1 1
1
4 2
109

S
h
89
400
1 0

,
i 14
1
8
1
a
2 7
Sft,200
2 0
1
b
I 7
41
1
S 2
160

a
2
42
20(1
1 9
20

129

*
1
9
2 9
BO,100
2 8
8
7
1 1
2 L
1
2 7
167

8
6
*>2
100
2 »
1 2
O
m
I
2
1
4
2 1
46 TOO
I 6
1
2
I 4
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5,0 EVALUATION OF RESULTS
5.1 CONTAMINANT SOURCES
Based on the evaluation of the Bulling process (Section 1.3), findings of
previous investigations and the RI field investigation,, the sources of
environmental contamination at the Cimarron site have been identified. The
sources of cyanide and elevated concentrations of metals consist of pro-
cessed waste material 
-------
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-------
liquids and the groundwater. The source of cyanide solution to the soils
was eliminated when the mill closed in 1982. Without a continued source of
cyanide and sufficient hydraulic head to induce recharge, in addition to
dilution and biodegradation considerations, it is expected that current
transport of cyanide contamination to the groundwater is negligible.
The HELP model application did not however, consider collection of precipi-
tation runoff. The cinder block trenches and the discharge pit act to
collect runoff water from their surrounding areas. This increases the
potential for further migration of contaminants from soils to the
groundwater during and after storm events. This potential migration route
could be addressed by filling in and grading those locations as discussed
in Section 11.4.
The findings of the HELP Model application can also be applied to assess-
ment of contaminant migration from the tailings piles. Emplacement of the
tailings in piles I, C and K as a slurry may have created saturated condi-
tions beneath these areas during the period of plant operation.
The areas of the site with elevated concentrations of metals, compared to
background surface soils concentrations, include all of the waste piles,
and those areas of the site identified as being contaminated with cyanide
in Figure 5-1.
The area of elevated concentrations of TAL metals in groundwater does not
coincide with the area of cyanide contamination of groundwater. Ground-
water contaminant distributions suggest that while the cinder block
trenches and, to a lesser degree, the discharge pit are the primary sources
of cyanide contamination to groundwater, elevated concentrations of TAL
metals appear to be most associated with the tailings disposal areas (waste
piles C, I and K). This interpretation is supported by data presented in
Table 4-18, particularly sampling results from monitor wells MW-01, MW-02,
MW-03 and MW-07.
5-3

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5.2 NATURE AND EXTENT OF CONTAMINATION
5.2.1 SURFACE AND SUBSURFACE SOILS
5.2.1.1 Cyanide in Surface and Subsurface Soils
Based on the RI field investigation results and findings of previous in-
vestigations, site surface soils are contaminated with cyanide in the loca-
tions and concentrations shown in Figure 5-1. The highest concentrations
of total cyanide in the surface soils are present in the discharge pit (7.0
to 46.5 mgAg) and in the area around the cinder block trenches (up to 20.4
tag/kg)• Areas subjected to incidental spillage of cyanide solution (around
process tanks, and pumping and conveying equipment) are contaminated at
levels ranging from <1.0 to 10.3 mgAg-
Total cyanide concentration in soils decreases significantly with depth in
most areas of the site. Samples collected during the preliminary sampling
program from the spillage area near the cinder block trenches showed a
decrease in concentration from 7.3 mgAg at 2 to 6" to undetectable levels
below 18". A similar relationship was found in surface soil samples H2-0Q1
and M2-002 near the cinder block trenches, with concentrations of total
cyanide decreasing from approximately 20 mgAg to 3 mgAg between 2 and 6".
Total cyanide concentrations in soils underlying tailings Pile I are com-
paratively low (2.0 mgAg at 2.5 to 3 feet), and decrease to undetectable
levels below a depth of 5 feet.
Total cyanide concentrations in discharge pit sediment, which wss subjected
to repetitive contact with waste cyanide solution during the period of
plant operation, were found by the RI field investigation to decrease from
32.7 mgAg at a depth of 0 - 1 foot to 10.4 ngAg at 4 - 4.5 feet. The
discharge pit is approximately 15 feet deep, thus the 4 - 4.5 ft. sample
location is actually 19 - 19.5 feet below the natural ground surface.
Subsurface soil sampling performed during the soil boring and monitor well
installation program, as discussed in Section 4.2.6, found no other subsur-
face soil cyanide contamination at a depth below 5 feet. A soil boring was
5-4

-------
not, however, drilled directly within the cinder block trenches. As
previously stated, the cinder block trences are considered to have been the
major sources of groundwater contamination. Thus, it is expected that
cyanide in soil below the cinder block trenches would be present to water
table depth. The concentration of total cyanide in sediment removed from
the cinder block trenches (piles J and L) was found to be approximately 30
mgAg-
Cyanide fate and transport are discussed in Section 6.0. Risks to human
health and the environment posed by the cyanide contaminated soils at
Cimarron are evaluated in Section 7.0.
5.2.1.2 Metals in Surface and Subsurface Soils
Elevated concentrations of TAL metals in the soils at the Cimarron site
appear to be primarily confined to the surface and near surface soils in
the areas of the site identified as being contaminated with -yanide in
figure 5-1. Soil samples collected at depths greater than five feet were
not found to contain elevated levels of TAL metals. Table 4-6 summarizes
surface soil samples with concentrations above background levels.
The TAL metals which are consistently present in concentrations greater
than background (Table 4-6) are iron, cobalt and copper, with concen-
trations greater than three times the background levels. Other metals
elevated to a lesser degree are arsenic, barium, beryllium, calcium,
chromium, lead, magnesium, manganese, mercjry, nickel, sodium, vanadium,
and zinc. Subsurface soil samples with elevated levels of TAL metals were
generally found at depths less than five feet. Additionally, comparison of
the elevated metals values at the site with typical concentrations found in
soils of the United States (Table 4-7) indicates that only cobalt, copper
and iron are present in higher than typical concentrations.
Metals fate and transport are discussed nn Section 6.0. Risks to human
health and the environment posed by the elevated metals in the soils at
Cimarron are evaluated in Section 7.0.
5-5

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5.2.2 WASTE PILES
As discussed in Section 4.2.4, the waste piles at the Cimarron site are
divided into the two categories of processed material, and unprocessed
material. All of the waste piles, with the exception of pile 0, appear to
be comprised of soil or ore material brought to the site. They differ from
the natural soil at the site primarily by higher concentrations of several
TAL metals.
The processed waste piles are those piles which were subjected to the
cyanidation process and include tailings piles I, C and K, and cinder block
trench sediment piles J and L. Piles I, C and K contain cyanide (total) in
concentrations ranging from 4.7 to 12.6 mg/kg, and piles J and L were found
to contain between 24.3 and 33.9 mgAg of total cyanide. The total volume
of material in piles I, C and K is approximately 1,285 yd1 and piles J and
L total approximately 100 yd1, not including the uncontaminated J ore pile.
As presented in Section 4.2.4, the waste piles have concentrations of
arsenic, barium, beryllium, calcium, chromium, cobalt, copper, iron, lead,
magnesium, manganese, nickel, sodium, vanadium and zinc, which are greater
than concentrations found in background soil samples. Copper, cobalt and
iron are most elevated, and are the only metals present at levels greater
than the range of concentrations listed for typical soils of the United
States (Table 4-7).
Risks to human health and the environment posed by the cyanide and elevated
metals in the waste piles are evaluated in Section 7.0.
5.2.3 AIR
As presented in Section 4.3.4, low levels of total cyanide were detected
during the RI air sampling program. The concentration of cyanide salts
which is reported to be immediately dangerous to life or health (IDLH) is
50 tag/a*. IHe highest observed total cyanide concentration was 30 ug/m»,
or 0.03 ajg/ta', which was a four-hour average sampling 0.227 m1 .of air at I
pile/5'/PM.
5-6

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As discussed in Section 4.3.4, data from the air sampling program with
respect to total dust and respirable dust is inconsistent. Respirable dust
is defined as airborne particulate matter with an aerodynamic diameter of
less than or equal to-10 microns. Total dust is a measure of all airborne
particulate matter. Respirable dust concentrations should be a fraction of
the total dust concentrations. However, in eight of the 12 pairs of data
collected at the Cimarron site, respirable dust concentrations exceeded
total dust concentrations.
Additionally, the field blanks have respirable dust measurements (0.10 and
0.16 mg/filter) which are greater than all but one of the reported respir-
able dust weights of the non-blank samples.
The above discrepancies in total and respirable dust measurements are .
within the "noise" range for this sampling technology. The "matched
weight" filter method of sample comparison accepts an error of ±100ng.
This degree of error is not uncommon, and most industrial hygienists would
accept it, because they would have limited concern for the low level of
dust demonstrated in this sampling program.
The evaluation of risks to human health and the environment posed by the
air pathway are presented in Section 7.0.
5.2.4 GROUNDWATER
5.2.4.1 Cyanide in Groundwater
Cyanide was not detected in any of the domestic wells sampled during the
investigation.
Cyanide contamination is present in several monitor wells across the site
(Section 4.2.10). The total cyanide concentrations range from less than
the detection limit of 10 ug/L to greater than 4,000 ug/L. Figure 5-2
shows the distribution of cyanide concentration in the shallow groundwater
across the site. Current New Mexico Water Quality Control Commission
Regulations criterion, and the proposed Safe Drinking Water Act standard
5-7

-------
SAMPUNC HlSTOftr or CYANIDE IN GROUND WAHN
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^7

-------
limit acceptable total cyanide concentrations to less than 200 ugA-
Application of this standard to the site affects the groundwater in the
area of monitor wells MW-4, MW-5, MW-6, MW-8, and MW-10. However, as
discussed in Section 2.5.2.5, the contaminated shallow groundwater unit at
the Cimarron site is not a direct drinking water resource, due to its poor
water yielding properties and generally poor water quality, which results
in its characterization as a Class IIIA aquifer. The standards are not
"applicable" since the contaminated groundwater is not currently being used
as a drinking water source, and they are not "relevant and appropriate"
because the shallow water bearing sandstone units do not yield enough water
for typical household use. However; as discussed below, the potential for
limited migration of contaminated groundwater to lower, productive water
zones does exist. Therefore, some remedial action on the cyanide ground-
water contaminated source area may be appropriate, so as to prevent poten-
tial impact to underlying drinking water aquifers.
The primary source area for the cyanide contaminated groundwater at the
Cimarron site is the cinder block trenches, and to a lesser degree the
discharge pit. The contaminated groundwater occurs in permeable Cretaceous
sandstone units. These sandstones are situated within thick, low perme-
ability shales and are horizontally discontinuous as shown in the geologic
cross-section Figure 2-5. The sandstone units are generally fine-grained
with thicknesses ranging from 4 foot to greater than 10 feet. As discussed
in Section 2.5, there is a strong downward groundwater gradient at the
site.
The contaminated groundwater, m the vicinity of the cinder block trenches,
most likely flows downdip within the permeable sandstone units until the
sandstone units pinch out against the shales. The contaminated water would
then disperse laterally within these sandstone units in the directions
perpendicular to the dip of the sandstones (northeast and southwest). This
explains the level of cyanide contamination observed in monitor well MW-S.
Groundwater unable to migrate further downdip or laterally within the sand-
stone units would continue to slowly migrate downward through the shale
units until reaching another more permeable sandstone unit, at which point
5-9

-------
the migration would proceed as described above. The downward rate of
migration of groundwater may be enhanced by the presence of fractures and
joints wichm the Cretaceous shales and sandstones. In general, however,
most of the fractures and joints encountered during drilling at the site
appeared to be sealed by iron precipitates. Thus, migration of
contaminants along the paths of the sandstone units to a deep acquifer in a
downgradient position to the site is considered unlikely based on existing
data showing very discontinuous sandstone units (Figure 2-5); and based on
chemical data from wells 12, 15, 16, and 17 (Figure 5-2).
No cyanide contamination has been observed in the deep monitor well
(MW-ll), which is located in the area of the site where the shallow ground-
water is most contaminated with cyanide. Low level cyanide contamination
(24 
-------
while the borehole was open to the 11-foot sandstone. The water levels in
this unit were approximately equal to the water level measured in MW-10.
Because the water levels in the two sandstone units are similar, the
11-foot sandstone is conservatively assumed to be in hydraulic connection
with the upper sandstone. The screened interval of MW-11 is not within the
11-foot sandstone, but rather in a deeper sandstone situated well below and
separate from the upper sandstone units by approximately 70 feet of dense
shale.
The area of highest cyanide contamination of groundwater (exceeding approx-
imately 1,000 ygA total cyanide) is estimated to be approximately 160 feet
in - ameter; and total thickness of the contaminated water yielding units
is approximately 14 feet. The porosity of the sandstone is estimated to be
15 percent. Therefore, the volume of cyanide contaminated groundwater
exceeding a concentration of approximately 1,000 ^g/L is estimated to be
42,223 cubic feet, or approximately 316,000 gallons.
5.2.4.2 IA1 Metals in Groundwater
The area of elevated concentrations of TAL metals in the groundwater is
different from that of cyanide contamination. Although elevated metals
concentrations are present in the groundwater near the cinder block
trenches and the discharge pit (especially cobalt). The area of the site
most affected by elevated metals concentrations in the groundwater is below
and downgradient of the tailings disposal area (Piles I, C and K), as
supported by data from monitor wells MW-01, MW-02, MW-03 and MW-07,
presented in Table 4-18.
It is surmised that the tailings are the primary source of elevated con-
centrations of metals in the groundwater. The milling process decreases
the grain size of the original ore, thereby greatly increasing the surface
area of material which is relatively rich in metals. As additional tail-
ings were empiaced as a slurry over existing piles, process water moved
through these tailings piles, leaching metals, salts and other consti-
tuents. Assuming saturated conditions existed to the water table during
5-11

-------
plant operation, migration of metals, in addition to some cyanide
occurrred.
As shown in Table 4-17, chromium, lead, iron, manganese and selenium are at
concentrations exceeding State and Federal groundwater and drinking water
criteria. Selenium, and the nonmetals chloride, sulfate, and total
dissolved solids which are at concentrations exceeding the drinking water
standards are also high in the off-site residential wells (Table 4-16
indicating that these constituents are naturally high in the Carnzozo area
groundwater. The pattern of fluoride concentration across the site, and
fluoride's non-association with the Billing process, indicate that fluoride
is naturally high in the shallow groundwater unit at the site. The
nonmetal nitrate, which can be a byproduct of cyanide biodegradation,
appears to be associated with the cyanide contamination at the site, and is
elevated above State and Federal standards in several wells (Table 4-17).
The New Mexico numerical groundwater standards are those concentrations
listed in Section 3-103 of the water Quality Control Commission
Regulations, except "when existing pH or concentration ... exceeds the
standard 	 When this occurs, the existing or background concentration
becomes the standard." (NMEID, April 1990), For instance, in the
Carnzozo area, it appears that iron, chloride, sulfate, fluoride, and TDS
all are naturally high in groundwater. With repect to the New Mexico
regulations, these background concentrations then become the standards
(NMEID, April 1990). Manganese also frequently exceeds the numerical
standards in natural groundwater in New Mexico.
With respect to the lead concentration of 0.056 mg/L (RW-07), this well is
an abandoned well at the State Highway Department field office located to
the north of Carrizozo. The well is no longer in use, and based on dis-
tance from the Cimarron site, on-site data, and data from other residential
wells, the elevated lead concentration can not be associated with the
Cimarron site.
As discussed in Section 4.2.10 and shown in Table 4-19, there is a signi-
ficant difference in some metals concentrations in filtered and unfiltered
5-12

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5.2.5 TANKS AND PROCESS CHEKICAL AREAS
The tanks and process chenucal storage areas at Cimarron hold cyanide
contamination and elevated metals concentrations, but are contained and
currently not serving as a source of environmental contamination.
Approximately twenty-five 200-lb drums of the metal strippers Qistrip and
Ampcep are located in the mam process building (Figure 5-1). According to
the Material Safety Data Sheets on these chemicals, they contain 15% potas-
sium cyanide, <1% lead oxide, and other proprietory chemicals. Discussion
with the manufacturers indicate that the proprietory chemicals are nitro-
aromatic compounds. Prior to the RI field investigation, approximately
ten, 200 lb. drums of concentrated potassium cyanide were also present.
The potassium cyanide drums were sold by the bankruptcy trustee arid removed "
from the site.
The drummed metal strippers within the process building contain 151
potassium cyanide. Residual' process chemical dust and solids spillage
areas within the process building also potentially contain high concentra-
tions of cyanide. These chemicals may pose a risk to humans or animals
that might enter the building. Additionally, the small amount of sediment
present in the cyanide solution tanks within the process building, and the
pressure filters located between the pregnant solution tank and the lab
building (Figure 1-2), are probably highly contaminated.
Materials present in the outdoor process tanks at the site were sampled
during the ESI (E&E, 1988). As discussed m Section 4.1, approximately 218
yd1 of mill sediment contaminated with 28 to 280 rag/kg of cyanide and
various metals with elevated concentrations is contained within those
tanks.
Risks to human health and the environment posed by this contaminated
material are evaluated in Section 7.0. feasibility Study considerations
for this material are presented in Section 11.4.
5-15

-------
source of potable water, however, is unlikely due to the low palatability
of the water and low yield of the lithologic unit. As discussed in Section
2.5.2, the aquifer does not yield enough water for typical household use.
Therefore, future use is unlikely.
To evaluate the possible risks that would occur if this water were used for
domestic purposes, the monitoring data are compared with established state
and federal Maximum Contaminant Levels (MCLs). Additionally, risks
associated with daily ingestion of the water from the shallow aquifer are
evaluated for those contaminants exceeding the criteria values. Child
intake of contaminated water is evaluated separately.
Consistent with EPA guidance, a 70 kg adult is assumed to consume 2 liters
of water each day, or almost 0.03 L/kg-d. On a body weight basis, children
tend to ingest more drinking water than adults. Therefore, to adequately
characterize possible RfD exceedances for contaminants contained in the
water, ingestion of one liter per day by a 10 kg child (0.1 L/kg-d) is also
evaluated. This scenario is consistent with EPA development of drinking
water Health Advisories for children. For chronic exposures, a maximum
onsite residence time of 30 years is incorporated into the evaluation,
yielding a lifetime average daily intake of 0.01 L/kg-d based on an adult
water intake rate.
7.1.3 TOXICITY ASSESSMENT
This portion of the risk assessment compiles available information on the
potential adverse health impacts of the contaminants of concern. This
includes a qualitative discussion of the types of effects associated with
each contaminant, the nature of the evidence indicating each type of
effect, available dose-response data and toxicity factors, and an evalua-
tion of the certainty of the qualitative and quantitative toxicity
information. identified quantitative toxicity factors, e.g., reference
doses (RfDs) for noncancer health effects and cancer potency factors ICPFs)
for carcinogens, are used to calculate risk estimates. Two major EPA
information sources were used to compile Agency-derived toxicity values.
Priority was placed on values listed in EPA's Integrated Risk Information
7-41

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System (IRIS), an on-line source of toxicity values which have been
validated Agency-wide (U.S. EPA, 1987 and updates). Where toxicity values
were not available in this source, values from EPA's Health Effects
Assessment Summary Tables (HEAST) were included as available (U.S. EPA,
1989c).
As discussed above, cyanide has been identified as the primary contaminant
of concern at the site. Cyanides, which may exist in many forms in the
environment, are poisonous because of the ability of the cyanide ion to
irreversibly bind to iron atoms in hemoglobin and the ability to inactivate
respiration at the cellular level. Cyanide is not classified as a
carcinogen, and tests for mutagenicity have been negative. The most
sensitive end point of toxicity involves the central nervous system which
is influenced by the effects of cyanide on respiration. While exposure to
high doses of cyanide can be very toxic, smaller doses of cyanide are
readily metabolized in the liver of humans and laboratory animals to
non-toxic metabolites that are excreted m the urine. A more complete
discussion of the toxicity of cyanides is provided as Appendix M.
Other toxic contaminants found at the site which were elevated in some
samples above concentrations determined to be representative of background
levels in groundwater or soils (as listed in Table 7-1) were also included
in the risk assessment. Below are brief summaries of the health effects
and available quantitative measures of toxicity for the inorganic compounds
determined to be present at the site at concentrations above background.
This analysis includes only those compounds which have documented toxic
effects and for which quantitative measures of toxicity are currently
available from EPA.
Arsenic: Oral or inhalation exposures to arsenic have been associated with
acute and chronic health effects. Acute effects include damage to the
gastrointestinal tract or respiratory tract following oral and inhalation
exposures, respectively. Chronic exposures results in changes in skin,
including hyperpigmentation and keratosis, peripheral neuropathy, liver
injury, and cardiovascular disorders. Arsenic is a known human carcinogen,
with oral exposures associated with skin and liver cancer, and inhalation
7-42

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exposures associated with lung cancer. No RfD value currently exists for
arsenic. The carcinogenic potency factor for ingestion exposures is 1.75
(mgAg-d)~1 / .and the unit risk factor for inhalation exposures is 4.3 x
lO'Vug/m1 (U.S. EPA, 1987).
Barium: Acute exposure to barium salts can result in gastroenteritis,
hypokalemia, and cardiovascular effects. Chronic exposure in occupational
settings is associated with baritosis — a benign, reversible pneumo-
coniosis. Based on studies on rats where inhalation exposures were
associated with fetotoxicity, and ingestion exposures with increased blood
pressure, chronic inhalation and oral RfD values of 1 x 10"4 and 5 x 10"1
mg/kg-d, respectively, have been established (U.S. EPA, 1989c). Barium is
not considered to be a carcinogen.
Chromium: Acute exposure to chromium may result in kidney damage following
oral exposure or damage to the nasal mucosa and septum following
inhalation. Chronic exposure to hexavalent chromium has resulted m kidney
and respiratory tract damage, as well as excess lung cancer following
occupational exposure and in laboratory animals. Only hexavalent chromium
is believed to be carcinogenic. Oral RfD values for trivalent and hexa-
valent chromium are 1.0 and 5 x ID'1 mgAg-d» respectively. For trivalent
chromium, the RfD is based on hepa to toxicity in the rat. Tor the hexa-
valent form, the RfD is based on unspecified pathological changes in rat
studies. No inhalation RfD values are currently available. The unit risk
value for inhalation o£ hexavalent chromium is 1.2 x 10'Vug/m1 (U.S. EPA,
1987).
Copper: Symptoms following acute exposures to copper vary with the route
of administration and type of compound. Inhalation exposures to copper
dusts result in symptoms similar to metal fume fever; inhalation of fumes
and salts result in irritation of the upper respiratory tract; and inges-
tion of copper sulfate can be fatal. Chronic toxicity in humans has been
documented only in sensitive populations (e.g., dialysis patients and
individuals with metabolic disorders). No toxicity factors for inhalation
exposures are currently available. Copper is not thought to be
carcinogenic. The RfD for oral exposures is 3.7 x 10"2 mgAg-d (calculated
7-43

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from an RfD for drinking water of 1.3 mg/L assuming two ;ters of daily
water consumption). This value is based on human studies, and is believed
to be protective for gastrointestinal irritation (U.S. EPA, 1989c).
Lead: Exposure to lead can result in impacts an the hematopoietic system,
the nervous system, cardiovascular system, and the liver or kidney. Lead
inhibits several biosynthetic enzymes, and (following chronic exposure) may
be associated with anemia, nervous system in]ury, and impaired mental
development. Young children appear to be especially sensitive to health
effects following low level exposure. No quantitative toxicity values are
currently recommended by the Agency for use in the evaluation of possible
health effects from environmental exposures to lead. Recently, however,
EPA has adopted a soil cleanup level of 500-1,000 ppm for total lead that
is considered by the Agency to be protective for direct contact with soil
in residential settings (Longest and Diamond, 1989). Selection of this
interim cleanup level was based on information indicating that "lead in
soil and dust appears to be responsible for blood levels in children
increasing above background levels when the concentration in the soil and
dust exceeds 500 to 1,000 ppm." As stated by CPA, actual uptake of lead
from soil is highly dependent upon site-specific factors such as the
bioavailability and particle size of the lead found at the site as well as
factors influencing exposure duration and magnitude (Longest and Diamond,
1989; Steele, et al., 1989). However, soil lead concentrations at the
Cimarron site are all well below this range of concern identified by EPA,
with most values in the tens of ppm or lower, and a maximum value of 336
ppm reported in waste pile D.
Manganese: inhalation of very high concentrations of manganese can caus®
pneumonitis. Chronic effects of manganese include irritability, walking
and speech disturbances, encephalopathy and progressive deterioration of
the central nervous system. Individuals with an iron deficiency may be
more susceptible to chronic manganese poisoning. The inhalation RfD value
of 3 x 10"1 mgAg-d is based on central nervous system effects in humans.
The oral RfD of 2 * 10"1 mgAg-d is based on central nervous system effects
m laboratory rats (U.S. EPA, 1989c).
7-44

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Mercury: Inhalation exposure to mercury can result in damage to the res-
piratory and nervous systems. Oral exposure can result in gastrointestinal
effects, and damage to the circulatory and nervous systems. No indication
of carcinogenic potential of this compound is available. Similarly, no RfD
value exists for the evaluation of inhalation exposures. An oral RfD value
of 3 x 10 mgAg-d has been established based on central nervous system
effects in humans (U.S. EPA, 1989c).
Nickel: Signs of acute exposure to nickel include headache, nausea, chest
pain, cyanosis, and central nervous system effects. Following chronic
exposure in occupational settings, damage to the nasal mucosa is one of the
most common effects. Nickel dust has been demonstrated to be a cause of
cancer in the lung and nasal cavity in workers exposed to certain nickel
compounds. Based on this evidence, a unit risk factor of 2.4 * 1.0'Vug/m1
has been established for nickel dust. Based on observed reductions in
organ and bodyweight of rats following oral exposures, an oral RfD of 2 k
10": mg/kg-d has been established (U.S. EPA, 1987).
Nitrate: Toxicity from exposure to nitrates results from the conversion of
nitrate to nitrite in the gastrointestinal tract. Nitrite, then oxidizes
hemoglobin to methemoglobin. Humans have been shown to be more sensitive
to the toxic effects of nitrates, and laboratory animals are not a good
model for predicting what human effects of exposure will be. Infants are
particularly susceptible to the toxicity of nitrates due to a high gastro-
intestinal content of nitrate-reducing bacteria, a lower capacity to reduce
methemoglobin to hemoglobin, and to the presence of fetal hemoglobin which
is more susceptible to oxidation. The oral RfD for nitrate, based on human
methemoglobinemia, is 1 x 10°. No inhalation RfD has been established, and
nitrates have not been evaluated by the EPA for human carcinogenic
potential (U.S. EPA, 1987).
Selenium: Acute exposure to selenium may result in central nervous system
effects and eye and nasal irritation. Chronic exposure to selenium can
result in discoloration of teeth, loss of teeth and hair, skin disorders,
and central nervous system effects. In animals, selenium has been shown to
cause sterility, lameness, and anemia. It may also be embryotoxic and
7-45

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teratogenic in animals. In laboratory studies, selenium has been shown to
be both a carcinogen and to be protective against carcinogenesis.
Currently, no quantitative measure of the carcinogenicity of selenium is
available. The inhalation RfD value of 1 * 10"3 mgAg-d and the oral RfD
value of 3 x 10"! mgAg-d are based on dermatitis and hair and nail loss
among exposed humans (U.S. EPA, 1989c).
Vanadium: Exposure to vanadium compounds by laboratory animals has been
shown to result in alterations in cystine metabolism, decreases in erythro-
cyte and hemoglobin levels, histopathological changes in lungs, and a
decrease in growth rate. No quantitative measure of inhalation toxicity is
currently available. Based on impaired kidney function seen in rats fed
sodium metavanadate, an oral RfD or 7 x 10"3 mgAg-d has been established
(U.S. EPA, 1989c). No qualitative or quantitative indication of carcinor
genicity of this compound is available.
Zinc: Acute exposures to zinc fumes can result in metal fume fever.
Ingestion exposures can result in gastrointestinal tract effects. Follow-
ing prolonged ingestion, zinc exposure may result in muscular stiffness,
loss of appetite, and nausea. No quantitative measure of inhalation
toxicity of zinc is currently available. An oral RfD of 2 x 10"1 has been
established based on observed anemia in humans (U.S. EPA, 1989c). No
qualitative or quantitative indication of the carcinogenicity of this
compound is available.
7.1.3.1 Methodology for Evaluating Potential Carcinogenic Health Effects
The potential for inducing carcinogenic health effects is typically
expressed quantitatively as a carcinogenic potency factor (CPF). Derived
from human epidemiological studies and experimental animal bioassays,
carcinogenic potencies are expressed in inverse units of mg of compound per
kg of body-weight per day ((mgAg-d)"1). Multiplication of the potency
factor by the exposure in corresponding reciprocal units (mgAg-d) results
in a unitless estimate of risk.
7-46

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area of the site near the cinder block trenches. As can be seen in Table
"7-34, almost none of the concentrations in this well exceed MCLs. The
exceptions are dissolved solids, chloride, fluoride, and lead. These
exceedances may be due to grout contamination which occurred during the
well installation. Law level cyanide contamination (0.024 mg/L), however,
was found in the abandoned deep water well m the southeast corner of the
site, as discussed in Section 5.2.4.
For comparison, monitoring results from the well upgradient from the site
are provided in Table 7-35. The "background" concentrations present in
this well exceed the MCL for dissolved solids, chloride, fluoride, and
iron.
For compounds exceeding the MCLs, oral RfD values exist only for chromium-,
cyanide, manganese, nitrate, and seLemum. Risks corresponding to drinking
water ingestion for these compounds are shown in Table 7-36. As can be
seen, if this groundwater were to be used as a drinking water supply, RfD
values would be exceeded for cyanide (4.1) and nitrate (3.5) in the adult
scenario and chromium +6 (1.9), cyanide (9.5), and nitrate (8.3) in the
child scenario. Maximum concentrations for these substances were reported
in two onsite monitoring wells (MW-02 and MW-04), thus, all of these
concentrations would not be simultaneously experienced. If, however, such
an exposure were possible, the total HI for drinking water ingestion would
be 8.7 for the adult scenario and 20.4 for the child scenario, values which
are well in excess of unity.
Summary of Risk Estimates
Many compounds are identified m the RI as elevated on the site compared to
background levels. Potential exposures to these contaminants and the
corresponding health risks under current conditions in the area and for a
hypothetical future population resident on the site are evaluated in the
endangerment assessment. Specifically, potential risks from incidental
ingestion and dermal contact with soils and sediments at the site, inhala-
tion of contaminated dusts, and consumption of contaminated groundwater are
assessed. Under current conditions at the site, no Hazard Index value
7-78

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TAHLi: 7-34
Comparison of Reported Concentrations in Onsitc Deep Well (MW-OI I)
with U.S. EPA MCLs and New Mexico WQC
Parameter Name
IDS
1 ss
anlinmny
arsenic
barium
beryllium
bicarbonate
cadmium
calcium
carbonate
chloride
chromium
cobalt
copper
cyanide
cyanide-SAS
fluoride
iron
lead
magnesium
manganese
mercury
nickel
nitrate
llllllt<.
Reported
Cone (ug/l)
2.500,0(10 0
12.300 0
8 0
5 I
239 0
0	S
1.000 0
1	0
221.000 0
160.000 0
350,000 0
21 8
1	5
59 8
5 0
5 0
7.1000
187 0
1.520 0
616 0
3 4
0 I
2	5
790 0
Si I 0
New Mexico
WQC (ug/l)
1.000.000
100
1,000
IJ S. I .PA
fue/h
50
I.0W)
10
250,000
50
1,000
200
200
1.600
1,000
50
200
2
10.000
10
50
4.000
50
RA I'lOOl
CONC TO
NM WQC I PA MCI.
10.000
2 so
0 OS
0 24
0 10
I 40
0 44
0 060
0 03
0 03
4 44
0 19
30 40
0 02
0 05
0 08
0 10
0 24
0 10
0 44
I 78
30 40
0 05
0 OR

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I A 111 .1 7-14 (Cont i nued)
Comparison of Reported Concentrations in Onsile Deep Well (MW-OI I)
with U S l.l'A MCl.s and New Mexico WQC
Parameter Name
p< w.issiuin
silver
sitJiiini
sulfate
v.m.iJium
/im
Reported
Cone (iig/l)
202.000 ii
2 o
S19.(XX) II
224,000 II
h /
200 (I
New Mexico
W(jC (UK/1)
U S l.l'A
MCI, (uti/l)
so
(rfMI. (MK>
I0.IXXI
SO
KA1IOOI
CONCTO
NM WQC l.l'A MCL
0 01
O 17
0 01
0 04
—I
I
Oo
o

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TABLE "~?5'
Comparison or" Reported Concentrations in Upgradient Shallow Well (MW-0I3)
uith L' S EPA MCLs and New Mexico WQC
RA TIO OF
Reported New Mexico U.S. EPA	CONCTO
Parameter Nane Cone (ue/1) WQC fug/1) MCL fue/n NM WQC EPA MCL
TDS
3,240,000 0 i
1,000.000

3 24

TSS
290.000 0 !




antimony
8 0 !




arsenic
4:;
100
50
004
0 08
barium
71 4
1.000
1,000
0 07
0 07
ber> Ilium
0 5




bicarbonate
88.000 0




cadmium
1 0
10
10
0 10
0 10
calcium
495.000 0 ;




chloride
857.000 0 '
250,000

3 43

chromium
10 5 1
50
50
0 21
0 21
cobalt
1 5




copper
U 0
1.000

0 014

c>snide
5 0 '
200

0 03

cvanide-SAS
5 0
200

0 03

fluoride
3.100 0
1,600
4,000
1 94
0 78
iron
4.770 0
1.000

4 77

lead
5 0
50
50
0 10
0 10
magnesium
117,000 0




manganese
28 3
200

0 14

mercury
o 3;
2
2
0 13
0 13
nickel
- 5




nitrate
6.900 0 |
10,000
10,000
0 69
0 69
nitrite
50 0 l




potassium
4,980 0




silver
2 0
50
50
004
0 04
sodium
271.000 0 1




sulfate
128.800 0 |
600.000

0 21

vanadium
18 3 j




nnc
43 4 i
10.000

000

7-81

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TABLE 7-36 Poiential Future Scenario - Water Ingestion
Estimated Hazard Indices for Adult and Childhood Ingestion of
Maximum Groundwater Concentrations Reported m On-Site Shallow Wells
Maximum Daily
Comoound
Cone
(ug/U
Iniake
(me'ke/dl
Oral R/D
(me/ke/d
•
Hazard
^DL'LT EXPOSURES
chromium *3 (insol)
n:
4 IE-03
1 0E»0O
4 IE-03
chromium *6
u:
4 IE-03
5 0E-03
8 1E-0I
. > anide
2 840
8 IE-02
2 0E-02
4 1E-00
manganese
o
^ 1
6 IE-02
2 0E-01
3 0E-0I |
nurate
124.000
3 5E-00
1 0E-00
3 5E-00
selenium
46
I 3E-03
3 0E-03
4 4E-0I
CHILD EXPOSLRES
chromium *3 (insol)
i-o
9 5E-03
1 OE-OO
9 5E-03 |
chromium *6
142
9 5E-03
5 0E-03
1 9E-00
;>anide
2,840
1 9E-01
2 0E-02
9 5E»0O
manganese
2.130
1 4E-0!
2 0E-01
7 1E-0I
nurak
124.000
8 3E»00
1 0E-00
8 3E*00
selenium
46
3 IE-03
3 0E-03
1 OE-OO
7-82

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exceeds unity, and the highest excess cancer risk for exposure resulting
from site visits or inhalation of fugitive dusts in Carrizozo is 4.7 x
10"'. Under a scenario of hypothetical future residence on the site, the
highest Hazard Irjdex is 9.5, corresponding to ingestion of contaminated
groundwater by a young child. The highest excess cancer risk is 8.7 x 10"6
(resulting from incidental ingestion of soils). The results of the
endangerment assessment are summarized in Table 7-37 and are discussed
below, by media.
Incidental ingestion of soil was evaluated for exposures by adults and
children from. Carrizozo and for hypothetical futuce on-site residents.
Soil ingestion did not result in contaminant exposures in excess of the RfD
m any of the scenarios examined. The tctal Hazard Index for childhood
ingestion of soil is estimated to be 0.32. This value does not take into
consideration the different adverse health effects or target organs of the
contaminants considered. Thus, the HI foe any specific health effect would
be less than this value. Hazard Index values are all based on single
visits to the site, since daily exposures are of interest when evaluating
RfO exceedances. The cancer risk value associated with onsite residence
{8.7 x 10"6 ) is higher than for the other soil ingestion scenarios
evaluated. This finding is expected since this scenario assumes 30 years
of daily exposure, whereas the risk values for adults and children in
Carrizozo are based on a single visit. Excess lifetime cancer risks
associated with soil ingestion are 7.0 * 10"10 and 1.4 x 10"' for Carrizozo
adults and children, respectively. Under the scenarios described above, to
reach an incremental risk of 10"4, an adult would have to visit the site
more than 1300 times (or once a week for more than 25 years). A young
child would have to visit the site more than 710 times, or once per week
for 13 years, to achieve this risk level.
Due to the low absorption of contaminants across skin, risks associated
with dermal absorption from soil are significantly lower than those asso-
ciated with incidental ingestion. Hazard Index values for all individual
compounds are well below unity. The total Hazard Index for dermal absorp-
tion of contaminants by a child is 0.02, with vanadium, manganese, copper,
and barium being the primary contributors to this value. Excess lifetime
7-83

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10.0 KEKEDIATZGN ALTERNATIVES
10.1 DEVELOPMENT OF REMEDIAL ACTION OBJECTIVES
Remedial action objectives axe proposed in order to -protect human health
and the environment. The objective specifies the contaminant(s) of
concern, exposure route(s) and receptor(s), and an acceptable contaminated
Tange for each exposure route. "Preliminary remediation goals are based,
where possible* on the hwlinw risk assessment, and Federal and State
ARABS.
As determined by the Eftdamjeiaeni Assess*--. 
-------
include semi-annual groundwater sampling and analysis for TAL metals and
cyanide for a period of 30 years. These 04M are estimated as follows:
Laboratory Analysis (assume 6 samples) $ 900
Labor for Semi-Annual Sampling
Indirect Costs
3,000
720
TOTAL COST
$ 4,620/6 months or
$ 9,240/year
Indirect costs include administration and reserve contingency funds. These
indirect costs are estimated above at 10 percent of direct annual costs.
Present worth analysis of O&M costs based on a discount rate of nine
percent over a 30-year period totals $95,000.
Evaluation of the No Action Alternative should consider the availability of
the preventative remedial option of filling and grading the cinder block
trenches and the discharge pit to ensure that on-site precipitation runoff
will not collect and infiltrate to the groundwater. Estimated additional
costs to the No Action Alternative that would be incurred if the cinder
block trenches and the discharge pit were to be filled in, compacted and
graded are as follows:
Labor and Heavy Equipment Usage Cost	$10,000
11.2.2 ALTERNATIVE 2 - INSTITUTIONAL CONTROLS
Description
Alternative 2 consists solely of institutional control measures designed to
isolate receptors from site-based risks. Under this alternative, no actual
remedial measures to directly address contaminated groundwater are imple-
mented; rather, legal controls, such as site access and land and ground-
water use and well construction restrictions, are employed to minimize the
likelihood of receptor contact with contaminated media. Monitoring of
groundwater as described for Alternat-ve 1 is included under Alternative 2
11-5

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Years 2-5
Lab Costs (assume 6 samples/year)
Labor
Indirect Costs
S 720
3,000
720
$ 4,440/year
Years 10, 15, 20, 25, and 30
Lab Costs (assume 6 samples per
sampling program
Labor
Indirect Costs
$ 720
3,000
720
$ 4,440/5 years
Present worth analysis of O&M costs is based on a discount rate of nine
percent, and totals $16,400 for year 1, $12,107 for years 2 through 5, and
$3,518 (total) for years 10 through 30. Total present worth cost of annual
groundwater sampling is $32,025. Total present worth cost for Alternative
3 is $211,725.
Additionally, as discussed in Section 11.2.1, consideration should be given
to the preventative remedial option of filling in the cinder block trenches
and the discharge pit so as to ensure that on-site precipitation runoff
will not collect and infiltrate to groundwater. Estimated cost for this
measure is $10,000.
11.2.4 ALTERNATIVE 4 - PUMP AND DISCHARGE GROUNDWATER TO A POTW
Description
The extraction well design previously described for Alternative 3 is
identical for Alternative 4. A proposed site plan for Alternative 4 is
presented in Figure 11-4. A two-inch diameter PVC well discharge header
would be installed below grade using a trenching machine. The pipe would
be brought above grade and secured inside the existing 24-inch diameter
stonnwater culvert underneath U.S. Highway 380. It is assumed that the
State Highway Department would allow this. On the south side of the
11-20

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EXISTING 24'0
CULVERT
TIE IN TO
EXISTING
5*0 PVC
SEWER TRAP
SCALE: 1
note, elevations shown are feet
ABOVE 5*00 FT. M.S.L ,
Sanitary sewer
FIGURE 11-4
ALTERNATIVE 4
PUMP it DISCHARGE GROUND WATER TO POTW

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highway, the pipe would be buried for approximately 200 feet to the
existing PVC sewer tap, located above grade. The extraction well pumps
would transport the estimated maximum 6 gpm flow of groundwater to this
sewer tap.
The sewer would convey Cimarron groundwater several miles to the Carrizozo
POTO, which has been previously described in Section 10.0. The estimated
flow to the POTO is 180,000 gallons per day, according to Carrizozo plant
personnel. This flow would provide sufficient dilution to reduce the total
cyanide concentration reaching the POTO to an estimated value of 208 yg/L»
assuming all of the pumped groundwater is contaminated with 4,330 j/g/L of
total cyanide, which is a conservative estimate. For comparative purpos-
es, State groundwater and Federal drinking water standards for total
cyanide are both 200 yg/L.
Biological activity with the existing treatment lagoons, coupled with plant
chlorination and photodecomposition, would constitute treatment to further
reduce the cyanide concentration.
with respect to nitrate, total dissolved solids (TOS), and total suspended
solids (TSS) loading to the POTW, the following calculations are made::
Assumptions
•	Average flow to POTW from the Cimarron site will be 8,640 gal/day.
•	Average flow to POTW from the town of Carrizozo is approximately
180,000 gal/day.
•	Although groundwater sampling data indicate a total suspended solids
(TSS) concentration of approximately 400 mg/L (see Section 11.2.3) it
is expected that this value resulted from monitor well installation
residual solids and would decrease significantly with pumping. Thus,
TSS concentration of the site groundwater is assumed to be 100 mg/L,
which is still a conservative estimate.
11-22

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•	Assume normal domestic wastewater in the Carrizozo POTW: influent
BOD5 = 200 mg/L; influent TSS = 200 mg/L; influent TDS = TDS in water
supply s 1,000 mg/L; influent ammonia =<25 mg/L; influent nitrate = 0
mg/L; and influent organic nitrogen = 10 mg/L.
•	Assume the following wastewater characteristics after treatment in
the POIW: effluent BOD = 30 - 50 mg/L; effluent TSS = 50 - 90 mg/L
(winter/summer); effluent TDS = 1,000 mg/L (unchanged by treatment);
effluent ammonia = 0; and effluent nitrate = 25 mg/L (all ammonia
converted to nitrate; assume no organic N is converted).
Nitrate
Nitrate in Carrizozo POTW effluent
-	180,000 g/d (25 mg/L)(0.34 x 10"6 ) - 37.5 lb/day
Nitrate contributed by site
-	6,640 g/d (124 mg/L)(8.34 K 10"6) - 8.9 lb/day
Estimated N03 concentration in combined effluent from VWTP -3.75
37.5 + 8.9
° 		 29 mg/L NO,
(180,000 + 8,640)(8.34 x 10"6)
This small increase in POTW effluent nitrate concentration should not cause
any significant increases in risk of nitrate contamination of groundwater
underlying land application sites.
TDS
TDS in Carrizozo POTW effluent
-	180,000 g/d (1,000 mg/L)(8.34 x 10"6) « 1,500 lb/day
TDS contributed by site
= 8,640 g/d (4,465 mg/L)(8.34 x io'6 ) = 321 lb/day
1,500 + 321 lb/day
Projected TDC in effluent « 		 - 1,157 mg/L
(180,000 + 8,640X8.34 x 10"6 )
11-23

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This small increase in POTW effluent TDS concentration should not result in
significant increases in soil salinity on land application sites.
TSS
TSS in Carrizozo POTW influent
» (180,000 g/d){200 mg/L)(834 x 10"6) o 300 ib/day
TSS contributed by the site
= (8,640 g/d)(100 mg/L)(8.34 x 10~6) - 7.20 lb/day
Increase in TSS load resulting from site groundwater
o (7.2/300)(100) o 2.4%
This small increase in TSS should have no adverse effect on the POTW.
Criteria Assessment
Alternative 4 would provide overall protection of human health and the
environment, by reducing the mobility and volume of cyanide in the shallow
aquifer. The toxicity of cyanide would be reduced through dilution and
treatment at the POTW.
The long-term risks associated with the Cimarron groundwater contamination
would be minimized. Short-term risks could be addressed by ensuring that
the sewer hookup is inaccessable to the public. Alternative 4 could be
readily implemented, since no special technologies would be required;
however, as discussed below, pretreatnent regulations exist regarding
discharge of waters from CERCLA sites to PCIWs.
Indirect Discharges
Under the pretreatment regulations of the National Pollutant Discharge
Elimination Requirements (NPDES), there are general prohibitions against
the introduction of any pollutants to the POTW which pass through or cause
interference {40 CFR 403.5(a)]. There are also specific prohibitions [40
CFR 403.5(b)]:
11-24

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1.	Pollutants which create a fire or explosion hazard;
2.	Pollutants which cause corrosive structural damage to the POTW, or
which have a pH lower than 5;
3.	Solid or viscous pollutants in amounts which cause obstructions to
the wastewater flow;
4.	Pollutants which cause interference with the POTW operation and
residuals (sludge) disposal; and
5.	Heat in excess of 40"C at the POTW.
The wastewater from Cimarron would not fall under any of these categories.
Discharge to POTWs must also be compliant with the local limits, if any,
established by City Ordinance [40 CFR 403.7]. These limits are designed to
prevent inhibition of the treatment process, interference, pass through of
pollutants which may cause environmental harm, sludge contamination, and
overload of compatible pollutants. The local limits are also designed to
protect worker health and safety, and will need to be defined by communi-
cation between EPA, NMEID and City officials.
According to U.S. EPA, February 1990, factors for determining a POTW's
ability to accept CERCLA wastewater include:
• The quantity and quality of the CERCLA wastewater and its
compatibility.
—	The quantity is approximately 6 gallons per minute.
—	The quality is conservatively estimated at 4,330 vg/L total
cyanide with a total solids concentration of 4,900,000 j/g/L.
—	Compatability of the waters should be adequate due to the
estimated dilution to 208 vg/L total cyanide. (Near drinking
water standards.)
11-25

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•	The impacts of a CERCLA discharge on the POTW's treatment system and
on it's continued compliance with NPDES.
—	NPDES not required because the POTW does not discharge to a
waterway.
•	The POTW's record of compliance with its NPDES permit and pretreat-
ment program requirements to determine if the POTW is a suitable
disposal site for the CERCLA wastewater.
—	The POTW is not required to have an NPDES permit.
•	The potential for volatilization of the wastewater constituents at
the CERCLA site, while moving through the sewer system, or at the
POTW, and its potential impact on air quality.
—	Measurable volatilization of the cyanide is not expected due to
dilution factors and slow reactivity of cyanide complexes except
under extreme pH and temperature changes.
•	The potential for groundwater contamination from the transport of the
CERCLA wastewater or impoundment at the POTW, and the need for
groundwater monitoring.
—	Dilution factors alone would decrease concentrations of cyanide to
near drinking water standards. Natural biodegredation processes
would account for additional reduction.
•	The potential affect of the CERCLA wastewater upon the POTW's
discharge as evaluated by maintenance of water quality standards in
the POW's receiving waters.
—	No receiving waterway for POTW effluent.
11-25

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•	The POTW's knowledge of and compliance with RCRA requirements or
requirements other than environmental statutes.
—	Determined as part of design investigation.
•	The various costs of managing the CERCLA wastewater, including all
risks, liabilities, permit fees, etc.
—	Determined as part of design investigation.
In addition to these factors, off-site discharges of CERCLA wastewaters may
only be made to facilities in compliance with the CERCLA off-site policy
(OSWER Directive 9834.11, November 1987).
Capital costs for Alternative 4, detailed in Table 11-2, are estimated at
$43,700. System operating costs are estimated at $18,800, based on 13
months of operation, as described for Alternative 3.
As presented for Alternative 3, present worth 04M costs associated with
continued groundwater monitoring would total $32,025. Total present worth
cost of Alternative 4 is $94,525.
Additionally, as discussed in Section 11.2.1, consideration should be given
to the preventative remedial option of filling in the cinder block trenches
and the discharge pit so as to ensure that on-site precipitation runoff
will not collect and infiltrate to groundwater. Estimated cost is $10,000.
11.2.5 ALTERNATIVE 5 - PUMP, TREAT AND DISCHARGE TO POTW
Description
Alternative 5 consists of an extraction well system identical to
Alternatives 3 and 4. Once above grade, all groundwater would be treated
prior to discharge to the POTO. The t eatment system is illustrated in
schematic form in Figure 11-5, and the site plan is presented as Figure
11-6. Treatment using the alkaline chlonnation technology (described in
11-27

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Cimarron Mining Corporation
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Record of Decision, Cimarron Mining Corporation Site:
Operable Unit 1 • Decision Summary; EPA; September 1990

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Decision Summary
Cimarron Mining Corporation Site
Operable Unit 1
Record of Decision
Seotember 1990

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DECLARATION FOR THE RECORD OF DECISION
CIMARRON MINING CORPORATION SITE
OPERABLE UNIT 1, CARRIZOZO, NEW MEXICO
Statutory Preference for Treatment as a
Principal Element 1s Met
and Five-Year Review Is Not Required
SITE NAME AND LOCATION
Cimarron Mining Corporation
Carrlzozo, Lincoln County, New Mexico
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the
Cimarron Mining Corporation site In Carrlzozo, Lincoln County, New Mexico,
which was chosen 1n accordance with the Comprehensive Environmental Response,
Compensation and Liability Act of 1980 (CERCLA), as amended by the Superfund
Amendments and Reauthorization Act of 1986 (SARA) and, to the extent
practicable, the National Oil and Hazardous Substances Pollution Contingency
Plan (NCP).
This decision is based uoon the contents of the administrative record
file for the Cimarron Mining Corporation site.
The United States Environmental Protection Agency and the New Mexico
Environmental Improvement Division agree on the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this site, 1f
not addressed by implementing the response action selected in this Record
of Decision (ROD), may present an imminent and substantial endangerment
to public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
This final remedy addresses remediation of shallow ground water contamination
at the Cimarron Mining Corporation (Operable Unit 1) mill location. The
principal threats posed by the site will be eliminated or reduced through
treatment and engineering controls.

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The major components of the selected remedy include:
o Pump and discbarge ground water to the Carrizozo Publicly Owned
Treatment Worki (POTW)
-	The discharge will comply with the pretreatment standard of 5 milligrams
per liter (mg/1) of cyanide as cited in 40 CFR 413.24 Subpart B and
deemed relevant for this action. Sampling will be conducted onsite
prior to the discharge entering the POTU collection system. Current
data indicates pretreatment will not be necessary.
-	Biological activity within the existing treatment lagoons, in addition
to effluent chlorination and photodecomposltion will provide treatment to
reduce the cyanide concentration to acceptable concentrations.
-	Monitoring of the treatment plant effluent and sludge will be
conducted to ensure no adverse impacts on the POTW processes.
CRITERIA: A treatment goal of 200 micrograms per liter (ug/1) of cyanide
will be utilized. If possible, for remediation of the shallow
ground water. New Mexico Water Quality Control Commission
Regulations requires protection of all ground water of less
than 10,000 milligrams per liter (mg/1) total dissolved
solias for potential future beneficial use as a source of
drinking water. In addition, this treatment goal will
provide protection of the lower, currently used drinking
water zone, from potential future migration of contamination.
o Ground Water Monitoring
-	The ground water monitoring program may be amended and/or eliminated if
data indicates effective remediation has occurred.
In addition to the ground water remedy, the following measures will be
impl emented:
o Removal of the process chemical drums, and decontamination of tanks
and associated piping;
o Filling 1n the discharge pit and cinder block trenches with onsite
soils and waste pile material and covering with clean fill;
o Plugging of the onsite abandoned water supply well; and
o Inspection and maintenance of the existing fence.

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STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment,
complies with Federal and State requirements that are legally applicable
or relevant and appropriate to the remedial action, and is cost-
effective. This remedy utilizes permanent solutions and alternative
treatment technologies {or resource recovery) to the maximum extent
practicable and satisfies the statutory preference for remedies that
employ treatment that reduces toxicity, mobility, or volume as a
principal element.
Because this remedy will not result 1n hazardous substances remaining
onsite above health-based levels, a five-year review of the remedial"
action is not required.
Robert E. Layton Jr(, P.
Date
Regional Administrator
U.S. EPA - Region 6

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Decision Summary
Cimarron Mining Corporation Site
Operable Unit 1
Record of Decision
I. Location ano General Description
The Cimarron Mining Corporation site is located approximate! y 1/4
mile east of Carrizozo, Lincoln County, New Mexico and approximately
100 miles south-southeast of Albuquerque. The site is about 10.6 acres
in size, and is located in the NE 1/4 Section 2, Township 8S, Range
10E, on the north side of U.S. Highway 380 (Figure 1). The facility
consisted of a conventional agitation mill, which resulted in
unpermitted discharge of contaminated liquids, the stockpiling of
contaminated liquids, and the stockpiling of tailings and other waste
sediment. Access to the site 1s restricted by a 8-foot fence.
Approximately 1500 people live within a two mile radius of the site.
While conducting the RI field work at the Cimarron site, the
existence of another abandoned mill became known. The other
location, known as Sierra Blanca, exists approximately one mile to
the south of Cimarron (Figure 1). The two mills were owned by the
same parent company (Sierra Blanca Mining and Milling Company) and,
for a short period, operated concurrently. File Information discusses
a possible spill at Cimarron, which prompted all milling operations
to be relocated to Sierra Blanca. Investigation of the Sierra Blanca
mill is being performed as a second operable unit of the Cimarron NPL
site, and the results will be presented as a separate RI/FS report.
II. Site History and Enforcement Activities
The Cimarron Mining Corporation site 1s an inactive milling facility
originally owned by Z1a Steel Inc., and used to recover Iron from
ores transported to the site. The iron recovery process took place
between the late 1960's and 1979 and involved crushing of the ore
material, formation of a pumpable slurry by mixing with fresh and
recycled water, and collection of the ferric (Iron) portion using a
magnetic separator. Cyanide was not used 1n this original process,
and tailings were transported from the site and used as fill material.
In 1979, the site was sold to Southwest Minerals Corporation, which
apparently began using cyanide soon thereafter to extract precious
metals from ore. Details on the operation between 1979 and 1981 are
not available other than a 1980 New Mexico Environmental Improvement
Division (NMEID) sample analysis report, which noted the presence of
cyanide contamination.
1

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54
'380
'¦SITE /
LOCATION
CARRIZOZO
54
CONTOUR INTERVAL: 100 FEET
SOURCE' USGS, Cimarron East-West, NM 7 5' Quadronglei, 1982.
N
o vao moo
rtrr
FIGURE 1
SITE LOCATION MAP
CIMARRON MINING CORPORATION
NEW
MEXICO
QUADRANGLE LOCATION
— CAWP DRESSER t. McKEE INC."

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ess* st funerals, a subsidiary of the Sierra Blanca Mining and
Slllna Company, operated without the requirea permits necessary for
nducting cyantde processing at the site. In mid-1981, the operation
*as expanded by adama several "large mixing tanks, cyanide solution
tanks, thickeners, and associated pumping and conveying equipment.
NH£I0 sent a certified notice of violations to Cimarron Mining
Corporation on June 22, 1982, for discharging into a non-permitted
discharge pit and, in July 1982, the site ceased operation. No legal
action was taken by the state; the company filed for bankruotcy in
July 1983, and a court assigned bankruptcy trustee was appointed for
the site.
NMEID field inspections of the site in February 1980, June 1982, and
1n Hay and June 1984 revealed the presence of cyaniae and elevated
metals in shallow ground water, soil and mill tailings.
An Expanded Site Inspection (ESI) was conducted from January to
October 1987, by an EPA Field Investigation Team (FIT). The objective
of the ESI was to collect additional data for the Hazard Ranking
System (HRS) and facilitate RI/FS planning. A topographic base map
indicating locations and elevations of on-site features is presented
in Figure 2.
On-site activities performed during the ESI included surface and
subsurface soil sampling, visual inspection of process tanks,
sampling of remnant materials in the tanks, quantifying waste
volumes, sampling and geologically describing subsurface soil borings
during Installation of monitor wells, sampling around water 1n the
monitor wells and in nearby water supply wells, testing 1n-situ
permeability at the monitor wells, and identifying adjacent land
uses.
Based on the findings of the site investigations and the preparation
of the HRS package, the Cimarron Mining Corporation site was proposed
for addition to the National Priority List (NPL) on June 24, 1988.
On October 4, 1989, the listing was promulgated.
In March 1989, EPA tasked the firm of Camo Dresser and McKee, an
Alternative Remedial Contracts (ARCs) contractor to conduct a
Remedial Investigation and Feasibility Study (RI/FS) for the site.
A preliminary sampling program was conducted on June 19-23, 1989,
to sample existing monitoring wells and known contaminant source
areas. Results of the preliminary sampling program were utilized to
refine the sampling plan for the extensive RI field investigation.
3

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CtMARRON MINING CORPORATION
CAFRIZOZO. MEW MEXICO
SITE MAP
MARCH 19

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The extensive RI field work and feasibility study began in August 1989
and was completed in June 1990. The data generated was used to
estimate the extent and magnitude of contamination at the Cimarron
Mining site and to develop and evaluate remedial alternatives. The
alternatives evaluated included various pump and treat alternatives
for the shallow ground water, institutional controls and no action.
Ill. Community Participation
Community interest in the Cimarron Mining site has been relatively
high due to the close proximity of the site to the town of Carrizozo.
Major community Interest has focused on alleviating the stigma of a
hazardous waste or Superfund site as it relates to the community and
the desire to have an expeditious solution to allow future industrial
development of the site.
A public "open house" workshop was conducted in May 1989 to inform
the community of the RI/FS activities and process and to answer any
questions. Approximately 35 people attended including out of town
individuals, representatives of the local newspapers and the New
Mexico Bureau of Mines.
Questions and comments ranged from concerns regarding the level of
site contamination, potential impacts on the community and possible
solutions to a disregard for the previous analytical data from the
site and an unwillingness to accept the potential of long term impacts
from the site contamination.
Numerous informal status briefings have been conducted with various
interested citizens and local officials Including presentations, by
invitation, at the local chapter of the Rotary Club.
In March 1990, a second public workshop was conducted to notify the
community of the preliminary R1 results and to answer questions.
Approximate!y 25 people attended this workshop. Most questions
evolved around potential remedial solutions and the schedule of
future activities. A major portion of the meeting involved
discussions of the "Sierra Blanca" operable unit and the responsible
party status of the town of Carrizozo, which leased the property
to the operators of the mill.
The RI/FS documents for the Cimarron Mining site and a Proposed Plan of
Remedial Action were released for public comment in July 1990.
Public notices were published in the Lincoln County News, fact sheets
were mailed to interested individuals and the documents were
available for review in local repositories. An "open house" public
workshop to discuss the Proposed Plan was conducted on July 16, 1990.
5

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Cost
Present worth costs of the six alternatives are as follows
Alternative 1
Alternative 2
Alternative 3
Alternative 4
Alternative 5
Alternative 6
532,000
145,000
212,000
95,000
136,000
184,000
None of these costs consider the additional preventative remedial option
of filling in the cinder block trenches and the discharge pit to ensure
that on-site precipitation runoff will not collect and infiltrate to
ground water. Estimated additional cost is $10,000. Additionally,
Alternative 4 and 5 might require on-site seoimentatlon prior to
discharge to the POTW. This would increase costs of these alternatives
by approximately $10,000.
Alternative 4:
IX. Selected Remedy - Pump and Oischarge Shallow Ground Water to POTW
As stated in the risk assessment, soil contamination at the Cimarron
site is below action levels, and the around water contaminant of
concern 1s cyanide.
A proposed site plan for the selected remedy 1s presented 1n Figure 17.
Extraction well pumps would transport an estimated maximum 6 gpm
flow of ground water to a sewer tap located approximately 200 feet
south of the site.
The sewer would convey Cimarron ground water several miles to the
Carrizozo POTW. The estimated flow to the POTW 1s 180,000 gallons
per day, according to Carrizozo plant personnel. Total cyanide
concentration reaching the POTW is estimated to be 208 ug/1,
assuming all of the pumped ground water 1s contaminated with
4,330 ug/1 of total cyanide, which was the highest detected cyanide
concentration. This is a conservative estimate, considering the
average concentration of cyanide detected was approximately iS00 ug/1.
For comparative purposes, Federal and State drinking water standards
for tota"\ cyanide are both 200 ug/1. The discharge to the POTW will
comply with the pretreatment standard of 5 ma/1 of cyanide as cited
in 40 CFR 413.24 Subpart 8 and deemed relevant for this action.
Biological activity with the existing treatment lagoons at the POTW,
coupled with effluent chlorlnation and photodecompositlon, will constitute
treatment to further reduce the cyanide concentration.
This remedy also Includes filling In the cinder block trenches and
discharge pit, plugging the abandoned water supply well and Inspection
and maintenance of the existing fence.
64

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Based on calculations, an estimated 133,242 lbs of suspended solids
could be introduced to the POTW. Potential impacts of contaminated
sol Ids have not-been quantified. If, however, the solids are found
to be a problem during the Design Investigation, they will be
removed at the Cimarron site, by sedimentation, prior to discharge
of the ground water to the POTW.
The goal of this remedial action is to restore the ground water to
its potential future beneficial use as a drinking water aquifer,
as required by the New Mexico Water Quality Control Commission
Regulations. A remediation goal of 200 ug/1 of cyanide will be
utilized, if possible, for the shallow ground water. Based on
information obtained during the remedial investigation, and the
analysis of all remedial alternatives, EPA and the New Mexico
Environmental Improvement Division believe that the selected remedy
will achieve this goal. Ground water contamination may be
especially persistent in the immediate vicinity of the contaminants'-
source, where concentrations are relatively high. The ability to
achieve cleanup goals at all points throughout the area of
attainment, or plume, cannot be determined until the extraction
system has been Implemented, modified as necessary based on engineering
design changes and plume response monitored over time. If the selectea
remedy cannot meet the health-based remediation goals, at any or all
of the monitoring points during implementation, contingency
measures and goals as discussed below may replace the selected remedy
and goals. Such contingency measures may also include ground water
extraction and onsite treatment. These measures are still considered
to be protective of human health and the environment, and are technically
practicable under the corresponding circumstances.
The selected remedy will include ground water extraction for the
estimated period of 13 months, during which time the system's
performance will be carefully monitored on a regular basis and
adjusted as warranted by the performance data collected during
operation. The operating system may include:
a)	discontinuing operation of extraction wells 1n the area where
cleanup goals have been attained;
b)	alternating pumping at wells to eliminate stagnation points; and
c)	pulse pumping to allow aquifer equilibration and encourage
adsorbed contaminants to partition into ground water.
65

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If, in EPA's judgement, implementation of the selected remedy clearly
demonstrates, in corroboration with strong hydrogeologlcal and chemical
evidence, that it will be technically impracticable to achieve and
maintain remediation goals throughout the area of attainment, the
contingency plan will be implemented. At a minimum, and as a necessary
condition for Invoking the contingency plan, 1t must be demonstrated that
contaminant levels have ceased to decline over time and are remaining
constant at some statistically significant level above remediation goals,
in a discrete portion of the area of attainment, as verified by multiple
monitoring wells.
Where such a contingency situation arises, around water extraction and
treatment would typically continue as necessary to achieve mass reduction
and remediation goals throughout the rest of the area of attainment.
If it 1s determined, on the basis of the preceding criteria and the
system performance data, that certain portions of the aquifer cannot be
restored to their beneficial use, all of the following measures involving long-
term management may occur, for an indefinite period of time, as a
modification of the existing system:
a)	low level pumping will be Implemented as a long-term gradient
control, or containment, measure;
b)	chemical-specific ARARs will be waived for the cleanup of those
portions of the aquifer based on the technical impracticability of
achieving further contaminant reduction; and/or
c)	institutional controls will be implemented to restrict access to
those portions of the aquifer which remain above health-based goals,
should this aquifer be proposed for use as a drinking water source.
The decision to invoke any or all of these measures may be made during
periodic reviews of the remedial action.
An Explanation of Significant Differences will be Issued to Inform the
public of the details of these actions when they occur.
Capital costs for the selected remedy are estimated at $43,700. System
operating costs are estimated at $18,800, based on 13 months of operation.
Present worth 0&M costs associated with continued ground water
monitoring would total $32,025. Total present worth cost 1s
$95,000.
66

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If on-site sedimentation were to be Included, based on the Remedial
Design Investigation, capital costs would increase by an estimated
$10,000 for on-site tank retrofitting and pumping equipment. As
previously stated, an agreement with the bankruptcy trustee has been
reached regarding the removal of the process chemical drums on site.
X. Statutory Determination
Actual or threatened releases of hazardous substances from this site, if
not addressed by implementing the response action selected in this Record
of Decision (ROOK may present an imminent and substantial endangerment
to public health, welfare, or the environment.
Pumping and discharge to the POTVJ would provide protection of human
Health and the environment by reducing the mobility and volume of
cyanide in the shallow aquifer. The toxicity of cyanide would be
reduced through treatment at the POTW. Hazard Indices for
noncarcinogens at the site will be less than 1 upon completion of
remedial activities. Additionally, implementation of the selected
remedy will not pose unacceptable short-term risks or cross-media
impacts. The selected remedy also meets the statutory requirement
to utilize permanent solutions and treatment technologies to the
maximum extent practicable.
The long-term risks associated with the Cimarron ground water
contamination would be minimized. Short-term risks could be
addressed by ensuring that the sewer hookup 1s inaccessable to the
public. The selected remedy could be readily implemented, since no
special technologies would be required; and, pretreatment
regulations which exist regarding discharge to waters from CERCLA
sites to POTWs will be met.
All Federal and State requirements for this remedy that are Applicable
or Relevant and Appropriate (ARARs) can be met through adequate
design and planning.
Long-term effectiveness is achieved through removal and ultimate
destruction of the contaminants of concern. In addition, treatment
is utilized to the maximum extent practicable 1n this alternative.
This remedy is cost effective 1n comparison to other
alternatives. The total cost of the selected remedy 1s estimated to
be $95,000 net present worth dollars (+501 or -301). Five-year
facility reviews will not be necessary for the soils since
67

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Cimarron Mining Corporation
Mining Waste NPL Site Summary Report
Reference 3
Excerpts From Hazard Ranking System Score Sheet and
Documentation for the Cimarron Mining Corporation;
R. Lowey, R. Rawlings, and S. Cary, EPA; November 26, 1985

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_ .	Claarroe Kinlag Corporation (aka Southvaat Minarala Cora.)
Fse#|fWW ——	——
Carrlzoto, !Jav Mexico
Iaumrr.
	**
»•*»«>-(M9* Of*• UCmr in bankruptcy; W. J. Cittlawan. Tmitu
H—	-- *• »•	Eavlinaa. 5. Cary ^ Nov. 26. 19flS
8»» snpw* * r*
[fy »|m>t Ky.	p* ODXU-na' Wl «* luSlUXH W.f«i«n rouu o' m*,»	 io«". «k.)
Milling nyf Hhti fnr th» rnnf»Btr«tinn nf pr»r
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DIRECT CONTACT
1.	OBSERVED INCIDENT
Oate, location, and pertinent details of incident:
NA
* • •
2.	ACCESSIBILITY
Describe type of barrier(s):
The mam mill facility is enclosed by a 6-foot chain link fence. However,
th* tailings disposal area is outside the fence, and access by th» general publi
is unrestricted (Ref. 2t pp. 7, 13, IS).
• * *
3.	CONTAINMENT
Type of containment, if applicable:
No form of containment is in use at the tailings disposal area (Ref. 2,
PP. 13. 15).
* * *
4.	WASTE CHARACTERISTICS
Toxicity
Compounds evaluated:
See GROUNDWATER ROUTE
Compound with highest score:
See GROUNDWATER ROUTE

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5
„ mast £ characteristics
Toil city and Persistence
Compounds evaluated:
Cyanide was Identified 1n the discharge
pit (Ref. 2, pp. 41.i 50), the tailing piles (Ref. 2, pp. 33-36), and holding
ponds (Ref. 2, pp. 49 i 54). Cyanide Mas also detected in a water sample*
from a monitor well onsite. (Ref. 2, p. 37) also see (Ref. 2, p. 15 map)
Liquid 1n onsite holding ponds contained coooer at a concentration of
30.500 ug/1 (Ref. 2. P. 53).
Liquid in onsite holding ponds contained nickel at a concentration of
475 ug/1 (Ref. 2, p. 53).
Compound with highest score:
Copper scores 18, based on a Sax toxicity level of 3 (Ref. 8, p. 6) and
a persistence value of 3 (Ref. 1, p. 18).
Hazardous Waste Quantity
Total quantity of hazardous substances at the facility, excluding those with
a containment score of 0 (give a reasonable estimate even if the quantity
Is above maximum):
The total quantity of *rdous substances at the site is £1^? cubic
yards (Ref. 9). This Includes «as.tes in the discharge pit (Ref. 2, p. 12),
the holding ponds (Ref. 5, p. 2)^he tailings disposal area (Ref. 2, p. 13),
The discharge pit and tallinqs area each
have containment scores of 3 (Ref. 1, p. 17).
The folding ponds each have containment scores of 1 (Ref. 1, p. 17).
Basis for estimating or computing waste quantity:
For the discharge pit and holding ponds, the once-filled operating
capacity was used (Ref. 9). Tailings volume was calculated based upon a
detailed survey of the tailings area (Ref. 9).
5. TARGETS
Ground Water Use
Uses of aquifer of concern within a three-mile radius of the facility:
Twenty-nine water wells have evidence to support their existence within
three miles of tne site of Cimarron Mining Corporation. Available Information
on these 29 wells are summarized in Reference 15, which Includes a stxnmary
table, a location map, and 23 well records obtained from tne State Engineer's
Office.

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6
Within three miles of the site the aquifer is used to supply water to
the town of Carnzoio's public municipal water system (Ref. 15; Ref. 17, p,
160). The aquifer also supplies water to private domestic wells and is
used locally to Irrigate food crops, forage, and a golf course (Ref. 15}.
The municipal water system 1s dependent on the aquifer for the major
portion of its supply. Some supplemental water Is available from Bonlto
Lake, in the Sacramento Mountains to the east. This source accounts for
about one third of the town's consumption during the summer, but 1t is not
large enough to be an alternative sole source of water for the town (Ref. 14).
Distance to Nearest Well
Location of nearest well drawing from aquifer of concern or occupied building
not served by a public water supply:
The nearest	iJckt/ well Is located in the WC*H SecU >
\b& (Ref. 15), Qufyf< iS'Pa&CvX'i.
Distance to above well:
The above well Is about 0.* miles fron the site (Ref. 15).
Population Served by Sound Water Wells UitMn ft 3-Wle Radius
Identified water-supply wells drawing from aquifer of concern within a 3-mle
radius and populations served by each:
U1th1n a 1-mile radius of the Cimarron Mining Corporation site, there
are 5 wells that provide water for household purposes (Ref. 15). Three wells
are used for domestic purposes only (3 * 3.8 ¦ 11.4 people). Two are used
both for domestic purposes ( 2 x 3.8 * 7,6 people) and irrigation. The
onsite well is presumably used for industrial supply when operational. To
summarize, within a 1-mile radius, it is estimated that (11.4 ~ 7.6 »)19
people may use private domestic Supply wells. However, most of these
households are win the town limits and probably have access to the
town's public water supply.
At distances of 1 to 2 miles from the site are 6 wells that provide
water for household purposes (Ref. 15). Two provide drinking water for the
approximately 1500 residents (Ref. 10) of Carrizozo. Another 1s to be used
for private domestic purposes only (3.8 people). Three wells are permitted
both for potable water for one household (3.8 peopl*)and for irrigation.
To summarize for the l-to-2 mile ring, private domestic wells supply I
households (7,6 people), one of which probably has access to the town's
water supply. Municipal wellf supply water for 1500 town residents.
Between the 2 and 3 miles distance from the site are 3 wells that
provide water for household purposes (Ref. 15). Two are used solely for
domestic purposes (2 x 3.ft ¦ 7.6 people). A second well is used both for
domestic purposes (3.8 people) and for irrigation. Two wells are not in
use. A total of (7.6 + 3.8 ¦ ) 11.4 people use the aquifer for a water
supply at this distance.

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7
To sunmarize, 2 municipal wells supply drinking water for the town of
Carrlzozo (Ref. 14; Kef. 17, p. 160), whose population 1s estimated to be
about 1500 people (R*fs. 10, 13). Twelve private wells are permitted for
use as domestic supplies for 10 households (Ref. 15). Assigning 3.e people
to each household {Ref. 1, p. 27), an estimated 38.0 additional people are
served. However, some of these households are probably hooked up to, or
hove access to the municipal supply and are not dependent on their private
•ells.
Computation of land area Irrigated by supply wells drawing from the aquifer
or concern within a 3-mile radius, and conversion to population (1.5 peoni»
per acre):
Within a 1-mlle radius of the Cimarron Mining Corporation site there
are 11 wells that provide water for irrigation (Ref. 15). Four of these
wells are used to irrigate the golf course and do not contribute to the
affected population. Five wells are used only for irrigation of at least
21 acres of fruit trees (21 * 1.5 • 31.5 people). Two are used both for
domestic purposes and for irrigation of at least 3.5 acres of food crops
(3x1.5 • 5.25 people). To summarize, within a 1-mile radius Irrigation of
food crops may affect (31.5 ~ 5.25 ») 36.75 people.
At distances of 1 to 2 miles from the site are 4 Irrigation wells (Ref.
15). One well Irrigates 5 acres of fruit trees (5 * 1.5 ¦ 7.5 people).
Three wells are permitted both for potable water ror one household and for
irrigation of 34 acres of fruit trees (34 t 1.5 people). To sunmarize,
irrigation 1n the l-to-2 mile ring accounts for an estimated (51 ~ 7.5 ")5B.5
people.
Between the 2 and 3 miles distance from the site are 3 irrigation wells
(Ref. 15). One well is used both for domestic purposes and for irrigation
of 42 acres of unknown crops. Two other wells are used strictly for irrigation
of a total of 2 acres of fruit trees plus garden (2 * 1.5 • 3 people). A
total of at least 3 people are potentially affected by irrigation of food
crops at this distance.
To summarize, 14 private wells and 4 town wells produce water that is
used to irrigate 185.8 acres (Ref. 15). The four town wells are used to
irrigate the 69.3 acre golf course (Ref. 22) and do not contribute to an
affected population. According to available well records, the remaining
14 wells are used to Irrigate a total of 116.5 acres (Ref. 15). The actual
crops irrigated cannot be documented in all cases, but 1t 1s known that
food crops, primarily fruit trees, are grown on at least 65.5 acres (Ref.
15). Application of the conversion, 1.5 people per acre, result 1n an
estimate of 98.25 people Indirectly affected through Irrigation of food
crops.
Total population served by groundwater within a 3-wlle radius:
The total population served by groundwater withdrawn from the aquifer
within three miles of the site Is estimated to be 1636.25. This total
Includes about 1500 people served by the town of Carrizozo municipal water
system (Ref. 10), 38.0 people potentially served by private domestic wells

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e
(Ref. 15), and the equivalent of 98.25 people in terms of Irrigated acres
of food crops (Ref. 15). This Information is summarized in the following
table:
stance
PEOPLE USING
HATER

>.1)
1rriq. domestic
munic.
total
0 - 1
36.75 19
0
55.75
1 - 2
58.5 7.6
1500
1566.1
2 - 3
3 11.4
0
14.4
0 - 3	98.25	38.0	1500	1636.2s
The assigned value for the population served 1s 3 (Ref. 1. P. 27).
This value is not altered by exclusion of the 38.0 people that may be using
private water supply wells or the 98.25 people that may be Affected through
irrigation of food crops.

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Cimarron Mining Corporation
Mining Waste NPL Site Summary Report
Reference 4
Excerpts From Fact Sheet, EPA's Preferred Remedy
for the Cimarron Mining Site; EPA Region VI; July 1990

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The Proposed Plan of Action for addressing cyanide contamination of shallow ground water at the Cimarron
Mining Superfund site is being proposed following a comprehensive evaluation of six remedial alternate es
Remedial alternatives are technologies, administrative or legal actions, or other possible solutions to protect
public health and the environment by correcting contamination at Superfund sites The remedial alterna-
tives considered for the Cimarron Mining site are descnbed m detail in the Proposed Plan of Action
The U S. Environmental Protection Agency (EPA) must correct contamination problems at the Cimarron
Mining Superfund site that may present risks to public health. A health study determined thjt health risks
could exist m the future if the ground water is used as a drinking water source or if it migrates to the lower
drinking water zone. To remedy shallow ground water contamination at the Cimarron site, EPA has pro-
posed the following alternative
EPA'S PREFERRED remedy
FOR THE CIMARRON MINING SITE
Carrizozo, New Mexico	July 1990
W
INTRODUCTION
ALTERNATIVE 4: PUMP AND DISCHARGE
GROUND WATER TO PUBLICLY OWNED
TREATMENT WORKS (POTW)
Alternative 4 consists of using extraction wells to
pump contaminated ground water to the surface and
discharge it to the public sewer. The extraction well
pumps would transport the estimated maximum 6
gallons per minute (gpm) flow of ground water to the
sewer.
The sewer could convey Cimarron ground water
several miles to the Camzozo treatment plant. The
discharge would comply with all pre treatment stan-
dards and sampling would be conducted onsite pnor
to the discharge entering the publicly owned
treatment works collection system. Current data
indicates pretreatment would not be necessary.
Biological activity within the existing treatment
lagoons, coupled with plant chlorination and photo-
decomposition, would constitute treatment to reduce
the cyanide concentration. Monitoring of the treat-
ment plant effluent and sludge would be conducted to
ensure no adverse impacts on the POTW processes.
The estimated total present worth cost of Alternative
4 is $95,000 based on 13 months of operation.
In addition, the following measures are proposed to
be implemented regardless of the ground water
remedy selected:
~	Removal of the process chemical drums and tanks,
J Filling in the discharge pit and cinder block
trenches with onsite soils and waste pile materi-
als and covering with clean fill;
~	Plugging of the onsite abandoned water supply
well.
THE NEXT STEP
RECORD OF DECISION AND RESPONSIVENESS
SUMMARY
The Record of Decision explains the final remedy
selected by EPA to correct contamination problems to
protect public health at a Superfund site. The final
remedy could be different from the preferred alterna-
tive, depending upon new information EPA may
receive and consider as a result of public comments
EPA will respond to comments in a document called
a Responsiveness Summary. The Responsiveness
Summary will be included in the Record of Decision
and will be made available to the public at the site
information repositories.
Following the selection of a final remedy, EPA de-
signs and implements the chosen remedy. This phase
of the Superfund process is known as remedial de-
sign/remedial action (RD/RA).

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PUBLIC COMMENTS INVITED
July 17 to August 17, 1990
Written Comments

Public Meeting
The public is invited to comment on the remedial
Additionally, oral comments will be accepted at a
alternatives described in the Proposed Plan and the
public meenng to be held:
Administrative Record. The public comment period


begins on July 17 and ends August 17,1990. Dunng

Monday, July 30, 1990
the public comment period, send your written com-

7 p.m. to 10 p.m
ments to:

City Hall


Carnzozo, New Mexico
Mr. Donn Walters


Community Relations Coordinator
o
If special assistance is needed because of
U.S. EPA Region 6 (6H-MC)
£-
physical limitations or visual or hearing
1445 Ross Avenue
Cx
impairments, call Mr. Donn Walters at
Dallas. Texas 75202

214/655-2240.



REMEDIAL DESIGN
Once the work plan is approved, the remedial design
phase begins. In the remedial design phase, all
technical drawings, specifications, and other sup-
porting documents are prepared. These design docu-
ments and cost estimates are used as the basis for
bids on site remedial work.
REMEDIAL ACTION
Following approval of the remedial design, the actual
construction or implementation of the final remedy
begins. This phase of the RD/RA is conducted by
contractors under the supervision of EPA.
OPERATION AND MAINTENANCE
When the remedial action is completed, a long-term
monitoring and maintenance program will be imple-
mented.
FOR MORE INFORMATION
EPA CONTACTS
If you have questions or need additional information,
please write or call:
Paul Sleminskl
Remedial Project Manager
U.S. EPA (6H-SA)
1445 Ross Avenue
Dallas, Texas 75202-2733
214/655-6710
Donn Walters
Community Relations Coordinator
U.S. EPA (6H-MC)
1445 Ross Avenue
Dallas, Texas 75202-2733
214/655-2240
Inquiries from the news media should be directed to
Roger Meacham, EPA Region 6 Press Officer, at 214/
655-2200.
ADMINISTRATIVE RECORD REPOSITORIES
The Administrative Record contains documents re-
lated to the Cimarron Mining site. You are encour-
aged to read the documents available at the following
repositories:
Carrlzozo City Hall
Carnzozo, New Mexico
New Mexico Environmental Improvement Division
1190 St. Francis
Santa Fe, New Mexico 87503
U.S. EPA Region 6
Library, 12th Floor
1445 Ross Avenue
Dallas, Texas 75202
PRINTED ON
RECYCLED PAPER

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Mining Waste NPL Site Summary Report
Clear Creek/Central City Site
Clear Creek, Colorado
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental Health and Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-W0-OO25, Work Assignment Number 20.
A previous draft of this report was reviewed by Holly Fliniau of EPA
Region VIII [(303) 293-1822], the Remedial Project Manager for the
site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
CLEAR CREEK/CENTRAL CITY
CLEAR CREEK, COLORADO
INTRODUCTION
This Site Summary Report for Clear Creek/Central City, is one of a series of reports on mining sites
on the National Priorities List (NPL). The reports have been prepared to support EPA mining
program activities. In general, these reports summarize types of environmental damages and
associated mining waste management practices at sites on (or proposed for) the NPL as of February
11, 1991 (56 Federal Register 5598). This summary report is based on information obtained from
EPA files and reports and on review of the summary by the EPA Region VIII Remedial Project
Manager for the site, Holly Fliniau.
SITE OVERVIEW
The Clear Creek/Central City site is located approximately 30 miles west of Denver, Colorado, and
includes the Clear Creek mainstem and the North and West Forks of Clear Creek. Active operations,
which began in 1859, include gold, silver, copper, lead, molydenum, and zinc mining. Initial
investigations at the site focused on the discharges of Acid Mine Drainage (AMD) and milling and
mining wastes from five mines/tunnels in the Clear Creek and North Clear Creek Drainages (see
Figure 1). The five mines/tunnels of interest are: (1) the Argo Tunnel; (2) the Big Five; (3) the
National Tunnel; (4) the Gregory Incline; and (5) the Quartz Hill Tunnel. The first two are portals
along Clear Creek and the last three are in the North Clear Creek Drainage. They are close to the
Cities of Idaho Springs, Black Hawk, and Central City and influence acid mine drainage on adjacent
stream courses (Reference 4, page 3).
A more recent investigation addressed contamination of the West Fork of Clear Creek as well as
additional contamination of the Clear Creek (mainstem) and North Clear Creek. The West Fork is
impacted by acid mine drainage and contaminated storm-water runoff entering at Lion Creek and
Woods Creek (see Figure 2) (Reference 2, pages 4-16 and 4-74)
There are three areas of remedial action (Operable Units) at the site: (1) mine-tunnel discharge
treatment; (2) tailings and waste-rock remediation; and (3) site-wide remediation. A Remedial
Investigation was performed from 1985 to 1987, during which time EPA determined that Feasibility
Studies should be conducted for each of the three Operable Units. Two Addenda to this Remedial
Investigation (for the Big Five Tunnel and the Argo Tunnel) were completed in 1988 to provide
1

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Clear Creek/Central City Site
FIGURE 1. CLEAR CREEK CENTRAL CITY STUDY AREA

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Mining Waste NPL Site Summary Report
FIGURE 2. WEST CLEAR CREEK AREA

-------
Clear Creek/Central City Site
adequate information for the three Feasibility Studies. (Reference 3, page 1-2, Reference 2, page 1-
1). Records of Decision (RODs) for Operable Units 1 and 2, describing the selected remedial
actions, were signed by the Regional Administrator in 1987 and 1988, respectively. The State of
Colorado officially requested that the third ROD be postponed until a Phase II Remedial Investigation,
addressing additional sources of stream contamination, was conducted. The Phase II Remedial
Investigation was completed in April 1990.
The primary concern at Operable Unit 1 is surface-water contamination which results from Acid Mine
Drainage emanating from the five tunnels and from seepage of ground water through tailings piles
(Reference 1, page 9). Potential receptors of contaminated surface water include inhabitants of the
area, downstream surface-water and ground-water users, and the terrestrial and aquatic wildlife
(Reference 1, page 1).
The primary contaminants of concern for human receptors in surface water include aluminum,
arsenic, cadmium, chromium (VI), lead, manganese, nickel, and silver. For aquatic receptors,
copper, fluoride, and zinc are added to the other contaminants listed.
Operable Unit 2 poses potential threats to human health and the environment through degradation of
surface-water quality caused by runoff from the tailings piles and/or collapse of the piles into the
Creeks, and through human uptake of metals through inhalation or ingestion (Reference 4, page 5-6).
The selected remedy for Operable Unit 1 (mine-tunnel discharge treatment) consists of the
construction of passive treatment systems to treat mine-tunnel discharges prior to discharge to surface
waters (Reference 1, page 9). The cost to implement this remedy is $25 million (Reference 1, page
30). The selected remedial action for the second Operable Unit (tailings and waste-rock remediation)
includes: (1) slope stabilization at the Big Five Tunnel and the Gregory Incline; (2) monitoring of the
gabion wall at the Gregory Incline; and (3) runon control at the Argo Tunnel, the Gregory Incline,
the National Tunnel, and the Quartz Hill Tunnel. The estimated present worth cost (in 1988 dollars)
for this remedial action is $1,049,600 (Reference 4, Abstract, Page 2). A remedial action for the
third Operable Unit has not been specified Completion of the site-wide study under the Phase II
Remedial Investigation is necessary before a ROD can be prepared for this Operable Unit
OPERATING HISTORY
The Clear Creek/Central City historical hard-rock mining site is one of the most mined areas in
Colorado. Data indicate that up to 25 mines and 6 milling operations are currently operating in
Gilpin and Clear Creek Counties. The area also includes over 800 abandoned mine workings and
4

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Mining Waste NPL Site Summary Report
tunnels. Mining activity in the Central City/Black Hawk area began in 1859 with placer gold mining.
Exploration tunnels were built from 1860 to 1937. Mining operations have included gold, silver,
copper, lead, molydenum, and zinc. Although mining operations have varied recently due to
fluctuating market prices, historically 85 per cent of the mining has been for gold, 10 per cent for
silver, and 5 per cent for copper, lead, molydenum, and zinc (Reference 5, Page 5).
The Argo Tunnel, the most extensive and probably the most complicated of the five tunnel/mine
systems at the site, is an abandoned mine-drainage and ore-haulage tunnel (Reference 6, page 1). The
Argo Tunnel is 4.16 miles long and is connected to eight major mining zones (Reference 3, page 1-
3). There are 36 laterals that branch from the Argo Tunnel, 10 of which connect to mine systems. It
is estimated that there are 91 surface openings and 21,400 feet of vein strike associated with the Argo
Tunnel system (Reference 3, page 2-2). In 1982, it was documented that the owner was using the
tailings near the Tunnel portal as decorative landscaping and was selling tailings samples to local
distributors The Argo Mill site is also a local tourist attraction, as it is listed in the National Register
of Historic Places (Reference 6, page 2).
In 1943, four miners were killed in a blow-out in the Argo Tunnel caused by mining activities. In
1980, a second blow-out occurred due to "natural" causes (i.e., the release of debris behind which
water was dammed) (Reference 6, page 4; Reference 3, page 1-6). As a result of the 1980 blow-out,
Clear Creek was "grossly contaminated" and showed "serious violation of metal standards" the next
day. (Reference 6, page 4; Reference 7, page 5) (Note that extensive information was not available
for the other tunnel/mine systems as was for the Argo Tunnel.)
The Clear Creek/Central City site was nominated for the NPL in 1982 and was added to the NPL in
1983 (Reference 3, page 1-1). A removal action was completed by EPA's Emergency Response
Branch at the Gregory Incline (in April, 1987) to protect human health and the environment from
hazards associated with the collapse of a retaining crib wall. EPA removed the wall, decreased the
slope of the tailings pile to stabilize it, and then constructed a gabion-basket retaining wall (Reference
1). A second removal action was completed in 1988, which entailed connecting several residents
(with contaminated wells in Idaho Springs) to the public water supply system.
This site is also listed under Section 304(1) of the Clean Water Act (CWA). This section requires that
states identify water bodies that are impaired with toxic substances, identify the responsible point-
source dischargers, and develop Individual Control Strategies (ICSs) for these dischargers. The
listing of this site under CWA Section 304(1) was intended to address surface-water discharges,
primarily from mining operations.
5

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Clear Creek/Central City Site
SITE CHARACTERIZATION
The environmental media affected by this site (surface water, sediment, ground water, and air) are
briefly described below.
Surface Water
Both Clear Creek, North Clear Creek, and West Clear Creek are adversely affected by metals
contamination from the mining activities that have occurred at the site. Furthermore, there are
several scattered wetland areas along North Clear Creek at points where the Canyon bottom widens.
As a result, Clear Creek is designated as a critical habitat (Reference 5, page 13).
Clear Creek drains an area of 259 square miles. Portions of the study area are used as municipal and
industrial water supplies and also for many recreational activities. It is estimated that 75 per cent of
the flow in the Clear Creek Diversions is used for municipal and industrial purposes. The remainder
is used for the irrigation of golf courses and parks (Reference 6, page 2).
Acid Mine Drainage and runon and runoff from tailings and waste-rock piles have affected surface-
water quality. In addition to the direct discharge from the mine tunnels, contaminated runoff may
enter Clear Creek and its tributaries during rapid snowmelt and storm events. The resulting surface
flow across the tailings and waste-rock piles dissolves soluble minerals and transports particulate
tailings and waste-rock materials into the Creeks (Reference 4, page 10).
In 1988, EPA conducted extensive surface-water sampling along Clear Creek and North Clear Creek
in the vicinity of the major tunnel discharges. It was found that the Argo and Big Five Tunnels, as
well as North Clear Creek, contributed iron, manganese, zinc, and aluminum (in that order) to Clear
Creek. These sources were also characterized by low pH and dissolved-oxygen concentrations. In
Clear Creek, elevated levels of manganese, flouride, and iron were found, along with lesser amounts
of aluminum, copper, and zinc. In sediments, the predominant metals were found to be iron and
aluminum, although arsenic, cadmium, chromium, copper, lead, and nickel were also detected in both
Creeks in all sediment samples. Toxicity testing demonstrated significant impairment of aquatic life
(Reference 2, pages 4-5 and 4-6).
In 1989, during the Phase II Remedial Investigation, EPA conducted extensive additional sampling of
the Clear Creek site to determine the type and extent of contamination, assess spatial variability in
surface-water chemistry, and provide data to model contaminant fate and transport (Reference 2, page
4-17). The data showed dissolved zinc concentrations exceeding existing, acute, and chronic water-
quality standards throughout the Clear Creek Basin In addition, dissolved cadmium, total
6

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Mining Waste NPL Site Summary Report
manganese, and dissolved copper standards frequently exceeded standards along specific stream
segments. Toxicity-testing data show that acute toxic instream conditions exist throughout the Clear
Creek area, including most major tributaries. Finally, samples collected during storm events typically
contain higher concentrations of suspended solids and pH than samples collected during normal high-
and low-flow conditions (Reference 2, pages 4-72 through 4-76).
Sediment
The 1990 Phase II Remedial Investigation (Reference 2) found that metal concentrations in sediments
in the mainstem of Clear Creek are consistently elevated downstream of the Argo and Big Five
Tunnels. Upstream of these two Tunnels, copper and aluminum levels in sediments increase after the
confluence with West Clear Creek. Downstream of the tunnels, arsenic, lead, and copper in
sediments increase beyond the confluence with North Clear Creek.
Ground Water
Ground water is found in limited quantities, and is associated with unconsolidated alluvium in Valley
bottoms. Fractured conduits are capable of carrying contaminated water from virtually any of the
local underground mines and mineralized areas, thus potentially causing the contaminated water to
intersect wells or other water sources at unpredictable locations (Reference S, pages 6 and 11).
During the Phase I Remedial Investigation, ground water was characterized at five sites in the Clear
Creek area, namely, the Gregory Incline and Tailings, the National Tunnel, the Quartz Hill Tunnel,
the Big Five Tunnel, and the Argo Tunnel and Mill. Sampling results are summarized in Table 1.
Overall, the results indicated that ground water at all five sites is acidic and contaminated with metals
exceeding human-health standards. In addition to high-metals concentrations, all of the ground-water
samples can generally be classified as a calcium-magnesium/sulfate type (Reference 2, pages 5-1 and
5-3).
From the water-level data, piezometric contour maps were constructed, indicating that ground water
flows in a downstream direction and, where enough data points are available, appears to flow towards
the adjacent stream channel. However, data gaps did not allow for quantification of ground-water
contributions to surface water, except at the Gregory Incline, where ground water input to the Creek
was estimated to be 0.001-0.023 cubic feet per second (cfs) (Reference 2, page 5-3).
7

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TABLE 1. SUMMARY OF GROUND-WATER QUALITY EVALUATED DURING THE TIIASE 1 REMEDIAL INVESTIGATION
- RANGE AND AVERAGE OF VALUES FOR SELECTED PARAMETERS
Site Nunc
Big Five Tunnel'
Argo Tumid1
Quarts Hill1
Gregory Incline1
NaltooaJ Tonne!'

Mm
Mix
Avg
Mm
Max
Avg
Mm
Max
Avg
Mm
Max
Avg
Mm
Max
Avg
Field Parameter
Specific
Conductivity
(pmho«/cm @
25"C)
2 042
2,760
2,4>7 3
808
2.000
1 330 9
3 49J
5,012
4,136 7
980
3 490
1.874 4
445
1 675
898 1
Temperature
CC)
8
14
10 8
7
16
9 5
3
15 5
7 46
6 3
17
10 2
4 2
11
6 8
pH (unib)
3 2
5 3
4 1
000
6 25
4 22
2 44
2 90
2 6 (dry)
(2 72)
5 60
4 10
3 7
5 65
4 49
I^b Parindtra
Total Diwolvcd
Solids (mg/l)
2,960
2 960
2 960
680
2 460
1.635
3.134
5,810
4.954
1 060
4.650
2,249
365
1,620
885
Sulfate (mg/l)
1,320
1 870
1,595
324
2 490
1,003 2
921
3,780
2.178
700
2,530
1,381 5
201
1 060
553 7
Aluminum {ftg/l)
301
210 000
41,667 3
<23
108,000
<57,225
66,600
216,000
110,883
50
36.400
9.335 4
74
9.150
3.899 8
Arientc (jjg/l)
< 1
39
<33 7
<4
120
<48 3
so
1,180
564 5
2
424
<48 3
<4
<10
<8
Cadmium C/jg/l)
9 9
IIS
50
<4
185
<73
352
640
500 3
<1
117
<22 5
10 6
97
36
Copper Oig/I)
62
15 000
3,424 6
<4
8,920
<3,380
42,500
84.100
54,516 7
9
5.000
<794 6
21
1,410
473
Iron (pg/1)
1,210
49,500
27,031 1
425
13,500
2,880 5
231,000
470,000
383.538 5
2 4
356,000
159,697 1
10
1,460
267 2
U*i (Mltl)
<5
277
<91
<3
525
<118
<5
291
<82 8
<2
148
<45 6
<3
76
<21 9
Manganc«e
13
37,700
3,881 7
20 7
82,600
17 223 9
142
153,000
JI.IJ4 3
42 5
128,000
18,467 5
14 4
47,200
10,727 6
7inc Oig'l)
3 100
17 300
9,218 6
292
39,600
15 000
76 000
116 000
102,633
1.730
21,400
7,938 6
2,800
19 800
8.574 4
'Reauiu from til welb tampled
Source Ckar Creek Ifauc II Remedial InveaUgtlioa Report, Apnl 1990

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Mining Waste NPL Site Summary Report
During the Phase II Remedial Investigation, sampling was performed at domestic wells in the vicinity
of Clear Creek. Foi all domestic wells sampled, Total Dissolved Solids (TDS) concentrations ranged
from 27 to 2,260 milligrams per liter (mg/1), pH ranged from 3.9 to 7.75 units, sulfate ranged from
8.8 to 1,300 mg/1, and zinc concentrations ranged from 8 to S,S60 micrograms per liter	If
data for one well is excluded, all wells exhibited TDS concentrations of less than 700 mg/1, sulfate
concentrations of less than 386 mg/1, and zinc concentrations of less than 516 (ig/l.
For purposes of evaluating potential risk to individuals utilizing ground water within the study area,
domestic-well analytical results were compared to Primary and Secondary Federal Drinking Water
Standards (DWSs). All wells met the Primary DWSs except one, which had a cadmium value of 28
Ugll (as compared to the standard of 10 ugl 1). The users of this well treat their well water, and were
notified of the potential health risk posed by the water quality This well is not used for drinking-
water purposes. Compared to Secondary DWSs, all but four of the wells showed at least one
exceedance. The parameters for which the standards were most commonly exceeded were iron (6),
manganese (8), pH (6 below a pH of 6.5), sulfate (3), and TDS (4). One well exceeded the zinc
standard of 5,000 /ig/l with a value of 5,560 /xg/1 (Reference 2, pages 5-29 through 5-31).
The Phase II Remedial Investigation also included an assessment of the impacts of ground-water
contamination on surface water. Ground-water quality was difficult to define for the study area
because the nonhomogeneity of mineralization and fault/fracture systems has caused variations in
bedrock geology in the Clear Creek Basin and subsurface mining-related activities have altered the
geochemistry and hydraulics of the bedrock ground-water system within individual mining districts.
Aluminum, iron, manganese, sulfate, and zinc in ground water recharge to surface water. It was
further found that Riverside Park and the Gregory Incline contribute the largest quantity of metals to
the surface-water system. The poorest ground water, with respect to DWSs, is found in areas where
historic mining has occurred. This includes the Lion Creek Canyon and Virginia Canyon areas where
high levels of TDSs, iron, manganese, and zinc concentrations and low pH were found in drinking-
water wells (Reference 2, pages 5-31 through 5-33).
Air
Dust and wind-blown particulates originating from tailings piles has been evaluated as a potential
exposure pathway. During the Phase II Remedial Investigation, ambient-air monitoring was
conducted from August 1989 through November 1989. Total Suspended Particulate (TSP) and the
micro-particulate (PM 10) samples were collected in Central City and analyzed for arsenic, beryllium,
cadmium, chromium, copper, lead, nickel, and zinc. The sample results are summarized in Table 2
(Reference 2, page 7-6).
9

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Clear Creek/Central City Site
TABLE 2. AVERAGE MONTHLY TSP AND PM10 METAL CONCENTRATIONS
MEASURED AT CENTRAL CITY IN 1989 On fig/m3)
Metal
Part/
Size
Aug.
Sept.
Oct.
Nov.
Arsenic
TSP
PM10
.0008
.0005
.0013
.0067
.0019
.0010
.0013
.0011
Beryllium
TSP
PM10
.0003
.0004
.0006
.0007
.0007
.0008
.0006
.0008
Cadmium
TSP
PM10
.0001
.0001
.0018
.0003
.0018
0005
.0017
.0026
Chromium
TSP
PM10
.0110
.0014
.0061
.0035
.0104
.0049
.0054
.0040
Copper
TSP
PM10
.1427
.0466
.1546
.0472
.1596
.0507
.1310
.0328
Lead
TSP
PM10
.0169
.0154
.0239
.0217
.0508
.0258
.0283
.0376
Nickel
TSP
PM10
.0099
.0083
.0080
.0091
.0099
.0125
.0106
.0098
Zinc
TSP
PM10
.0831
.0528
.0821
.0497
.1439
.0569
.0764
.0311
Source- Clear Creek Phase II Remedial Investigation Report, April 1990
ENVIRONMENTAL DAMAGES AND RISKS
The Phase II Remedial Investigation provides an assessment of the risks to human health associated
with the Clear Creek Site. Table 3 presents a summary of this assessment, including: (1) exposure
media; (2) potentially exposed populations; (3) exposure routes; and (4) results (Reference 2, pages 9-
25 through 9-29).
Overall, risks to human health are not expected from ingestion of surface water when used as
drinking water, ingestion of surface water while swimming, or ingestion of fish, based on the
exposure scenarios evaluated in this assessment. There are potential risks associated with ingestion of
ground water, incidental ingestion of tailings, and inhalation of airborne dust. Arsenic contributes
10

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Mining Waste NPL Site Summary Report
most significantly to risks from ground water and tailings. All of the chemicals evaluated for the
inhalation pathway pose risks to human health. Lead exposures from ingestion of soil, dust, and
ground water pose potential risks to children (Reference 2, page 9-77).
It was determined during the Site Investigation that Clear Creek, between the Argo Tunnel and
Golden, Colorado, "can not support fish due to the contamination caused by mining activity"
(Reference 7, page 6). Contaminants of concern for aquatic life are aluminum, arsenic, cadmium,
chromium, copper, fluoride, lead, manganese, nickel, silver, zinc, and low pH. During the Phase I
Remedial Investigation, concentrations of these chemicals in Clear Creek, North Clear Creek, and in
the wetland below National Tunnel were compared to Federal Ambient Water Quality Criteria
(AWQC) or to the Lowest-Observed-Effect Level (LOEL). Criteria for aluminum, cadmium, copper,
lead, manganese, silver, and zinc were exceeded in Clear Creek and North Clear Creek. In North
Clear Creek, critieria for pH were also exceeded. In the wetland, criteria were exceeded for
aluminum, cadmium, copper, manganese, silver, zinc, and pH (Reference 2, page 9-3).
The Phase II Remedial Investigation focussed on the potential risks to Trout and macroinvertrebates at
the site. It was found that Trout could be acutely affected in the mainstem of Clear Creek, North
Clear Creek, and West Clear Creek, along with numerous tributaries of the streams. In addition,
virtually all of the Tunnel discharges are expected to be acutely toxic to fish (Reference 2, page 9-
77).
In the mainstem of Clear Creek and several of its tributaries, Trout are at moderate to high risk of
adverse chronic (reproductive) effects. In North Clear Creek, there is a clear risk of adverse
reproductive effects Potential risks of adverse reproductive effects are high in West Clear Creek
from Woods Creek to the confluence of Clear Creek. Chemicals in Lions Creek and Woods Creek
are likely to cause chronic effects.
Zinc sediments could cause adverse reproductive effects in all stream segments that were evaluated.
Arsenic, cadmium, copper, and lead in sediment pose chronic risks at some locations (Reference 2,
pages 77 and 78).
REMEDIAL ACTIONS AND COSTS
The selected remedy for Operable Unit 1 (mine-tunnel discharge treatment) consists of the
construction of passive treatment systems to treat mine-tunnel discharges prior to discharge to surface
waters. If the desired upstream water-quality concentrations can not be achieved by passive
11

-------
Clear Creek/Central City Site
TABLE 3. SUMMARY OF HUMAN EXPOSURE PATHWAYS EVALUATED FOR THE
CLEAR CREEK SITE
Exposure
Medium
Potentially Exposed
Population
Exposure Route
Results of Evaluation
Surface Water
Children iwimming in
creeks
Incidental ingestion
All chemicals below target
concentrations Swimming does not
appear to poae a threat

Residents obuuning drinking
water from surface water
Ingestion
Contact with North Clear Creek may
cause dermal irntauon. Mine
visiton contacting ponded water or
mine discharges could be subject to
corrosive skin-imtation bum*

Residents/vacationers
Dermal contact (with low pH water)
All chemicals below target
concentrations Swimming does not
appear to pose a threat
Fiih
Residents fishing in Clear
Creek
Ingestion
All chemicals below target
concentrations Ingestion of fish
does not appear to pose a threat
Ground Water
Residents obtaining drinking
water from ground water
Ingestion
Several chemicals detected in wells
above target drinking-water
concentrations Ingestion of ground
water may pose adverse health
effects
Tailings
Children playing on tailings
piles
Incidcnnal ingestion
Cancer risk range 1 x 10* to
6 x 10'

Future residents
[ncidential ingestion
Could be as much as 10 times the
nsk of children playing on piles
Air
Central City residents
Inhalation
Cancer nsk range 6 x10s (using
average chemical concentration) to
1 x 10" (using maximum chemical
concentration)

Central City residents
Ingestion of nonrespirable dust
particles
Not expected to add significantly to
dusl-exposure nsk because inhalation
route is more toxic for the chemicals
evaluated

Children playing on tailings
piles
Inhalation of chemicals in dust
Children playing on piles in acUvities
that generate significant dust could
be at greater nsk than residents
Source Clear Creek Phase n Remedial Investigation Report, April 1990
12

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Mining Waste NPL Site Summary Report
treatment, either a combination system (consisting of passive and active treatment) will be constructed
or an active treatment system will be constructed (to treat mine-tunnel discharges prior to discharge to
surface waters). The cost for passive treatment is approximately $2.5 million. An active treatment
system would cost approximately $7.7 million, and a combination of the two treatments would cost
close to $9 million (Reference 1, page 30).
The selected remedy for Operable Unit 2 (tailings and waste-rock remediation at the Argo Tunnel,
Big Five Tunnel, Gregory Incline Tunnel, National Tunnel, and Quartz Hill Tunnel) consists of slope
stabilization and runon control to reduce human exposure. The Big Five Tunnel and the Gregory
Incline tailings and waste-rock pile are sources of potential human and environmental exposure
through the collapse of tailings and waste-rock piles into streams. Therefore, the remedy for the Big
Five Tunnel is to regrade and stabilize the slopes on both sides of the Creek and place rock rip-rap on
the slope toe to protect the slope from eroding and collapsing into Clear Creek. In addition, the
gabion-basket wall (constructed by EPA at the Gregory Incline) will be maintained until monitoring
indicates remediation is necessary or until the tailings are removed for reprocessing (Reference 4,
Abstract).
The migration of contaminated water from runon and runoff over the five tailings and waste-rock
piles will be controlled by constructing upgradient ditches. This will effectively remediate runon
problems. The cost for remediation of Operable Unit 2 was estimated at $1,049,600 in the ROD
(Reference 4, Abstract, page 2)
CURRENT STATUS
Operable Unit 1 (mine-tunnel discharge treatment) is now in the remedial design phase for which
EPA is conducting a Treatability Study. Operable Unit 2 (tailings and waste-rock remediation) has
been split into two stages for remediation. The first stage consists of three properties and is in the
remedial action phase, and the second stage consists of two properties and is in the remedial design
stage. The Feasibility Study for Operable Unit 3 is being finalized by the Colorado Department of
Health. EPA Region VIII expects to complete a ROD by the fourth quarter of 1991.
13

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Clear Creek/Central City Site
REFERENCES
1.	Superfund Record of Decision: Clear Creek/Central City Site; James J. Scherer, EPA Region
VIII, Regional Administrator; September 30, 1987.
2.	Clear Creek Phase II Remedial Investigation Report, Volume 1 - Text - DRAFT; Camp, Dresser
& McKee; April 1990.
3.	Remedial Investigation Report - Addendum Number 2 - Argo Tunnel - DRAFT; Clear
Creek/Central City, Colorado; EPA; July 1988.
4.	Superfund Record of Decision: Central City/Clear Creek, Colorado; James J. Scherer, EPA
Region VIII, Regional Administrator; March 31, 1988.
5.	Preliminary Assessment of the Environmental Effect of Mine Drainage on the North Fork of Clear
Creek, Gilpin County, Colorado, Fred C. Hart Associates, Inc; July 30, 1982.
6.	Preliminary Assessment of the Environmental Effect of Mine Drainage from the Argo Tunnel,
Clear Creek County, Colorado; Fred C. Hart Associates, Inc.; July 22, 1982.
7.	Site Inspection Report; William Rothenmeyer, EPA Principal Inspector; June 30, 1982.
14

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Mining Waste NPL Site Summary Report
BIBLIOGRAPHY
Camp, Dresser & McKee. Clear Creek Phase II Remedial Investigation Report, Volume 1 - Text -
DRAFT. April 1990.
EPA. Remedial Investigation Report - Addendum Number 2 - Argo Tunnel - DRAFT, Clear
Creek/Central City, Colorado. July 1988.
Fred C. Hart Associates, Inc. Preliminary Assessment of the Environmental Effect of Mine Drainage
from the Argo Tunnel, Clear Creek County, Colorado. July 22, 1982.
Fred C. Hart Associates, Inc. Preliminary Assessment of the Environmental Effect of Mine Drainage
on the North Fork of Clear Creek, Gilpin County, Colorado. July 30, 1982.
Holcomb, Brenda (SAIC). Telephone Communication Concerning Clear Creek/Central City Site to
Holly Fliniau, EPA Region VIII, June 12, 1990.
James J. Scherer, (EPA Region VIII, Regional Administrator). Superfund Record of Decision- Clear
Creek7Central City Site; September 30, 1987.
James J Scherer, (EPA Region VIII, Regional Administrator). Superfund Record of Decision:
Central City/Clear Creek, Colorado; March 31, 1988.
Leet, Maria (SAIC). Telephone Communication Concerning Clear Creek/Central City Site to Holly
Fliniau, EPA Region VIII. August 16, 1990.
William Rothenmeyer (EPA Principal Inspector). Site Inspection Report. June 30, 1982.
15

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Clear Creek/Central City Site
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From Superfund Record of Decision: Clear Creek/Central City Site;
James J. Scherer, EPA Region VIII, Regional Administrator;
September 30,1987

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EPA/BOO/H08-87/016
Enwom
H**ct
Pmma**	S«Km«t~ iat7
EPA Superfund
Record of Decjsitn:
Central City/Clear Creek, CO

-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION Vl'li
18tn STREET-SUITE 500
OENVER, COLORAOO 80202-2*05
CLEAR CREEK/CENTRAL CITY SITE
DECLARATION FOR THE RECORD OF DECISION
DECISION SUMMARY
COMMUNITY RELATIONS RESPONSIVENESS SUMMARY
OPERABLE UNIT NO. ONE
Clear Creek and Gilpin Counties, Colorado
S«ptemb«r 30, 1987

-------
DECLARATION -OR THE RECORD OF DECISION
SITE NAME AND LOCATION
Clear Creek/Central City Sice
Clear Creek and Gilpin Counties, Colorado
Operable Unit No. One
STATEMENT OF PURPOSE
This decision document represents the selected remedial action for Operable
Unit No. One of the Clear Creek/Central City sice developed in accordance
with the Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA), as amended by the Superfund Amendments and Reauthorization
Act of 1986 (SAHA), and to the extent practicable, the National Contingency
Plan.
The State of Colorado has been consulted on the selection of remedy. The
State of Colorado has neither concurred nor non-concurred on the selection.
STATEMENT OF BASIS
This decision is based upon the Administrative Record for Operable Unit No.
One of the Clear Creek/Central City site (the index of vtuch is attached in
Appendix C). The index identifies the items vhich comprise the
Administrative Record upon vhich the selection of the remedial action is
based.
DESCRIPTION OF SELECTED REMEDY
Lov pH nine tunnel discharge water is only one of several sources to the
degradation of vater quality and aquatic habitat at 'he Clear Creek/Central
City site. Data gathered dur.ng -he re-ediai :n.es' :ganon ^as sho-n :nat-
-1-

-------
0
Runoff from tailings and vaste rock piles contain dissolved and
suspended metals.
o Tailings and vaste rock piles adjacent to Clear^Creek. and North
Clear Creek are unstable and could collapse into the creeks. These
piles have the potential to produce acid. Vhen introduced to vater,
the pH vill rapidly decrease and significant amounts of metals vill
be released to the environment.
o Hydrostatic pressure vill build up in the tunnels due to cave-ins.
After sufficient pressure has built up, the tunnels vill blov out,
releasing large volumes of dissolved and suspended metals to the
creeks.
o The ground vaters in the vicinity of the acid mine discharges are
contaminated.
o There are additional sources of lov pH mine tunnel discharges and
tailings upstream of the site that could be contributing dissolved
and suspended metals to the streams.
All of the above factors contribute to vacer quality and aquatic habitat
degradation .and vill be studied in the folloving subsequent operable units:
Operable Unit No. Tvo - Tailings and Vaste Rock Remediation
Operable Unit No. Three - Source Control
Operable Unit No.	Four - Blovout Control
Operable Unit No.	Five - Regional Ground Vater Contamination
Operable Unit No.	Six - Upstream Mine*Discharges and Tailings
These operable units are subject to change.
The selected remedy for Operable Unit No. One of the Clear Creek/Central
City site consists of treatment to meet upstream vater quality
concentration for contaminants of concern identified in the remedial
investigation (RI) in a treatment system discharge line. The upstream
vater quality concentrations vill be used as operational standards for this
interim remedy. The upstream vater quality concentrations ("upstream
levels") consist of the geometric mean of the subset of RI samples taken on
Clear Creek immediately upstream of the discharge from the Big Fi-e Tunnel
and on North Clear Creek immediately upstream o£ the discharge froT. rhe
-2-

-------
Gregory Incline. These upstream levels are not to be considered as final
applicable and/or relevant and appropriate requirements for the final site
remedy•
Because a determination of the final remedy is contingent upon the
completion of the other operable units listed above, the selected remedy is
an interim remedy. This interim remedy vlll consist of construction of
passive treatment systems to treat the low pH mine tunnel discharge from
each tunnel prior to discharge to surface vaters. This is the preferred
alternative and is contingent upon the results of ongoing pilot plant
studies demonstrating that upstream levels can be met by a passive
treatment system. If the upstream levels cannot be met by passive
treatment, then either of the folloving treatment systems vill be built:
o a combination system consisting of passive and active treatment
systems vlll be constructed. A phased approach to construction vill
be utilized.
o tvo active treatment systems (chemical precipitation or
electrochemical precipitation) vill be constructed to treat mine
tunnel drainage prior to discharge.
These systems vill be designed to reduce the mobility, toxicity or volume
of dissolved apd suspended metals in the mine drainage, increase pH, and
meet upstream levels. Upstream levels are listed In the Selected Remedy
section.
A pilot-treatment system for passive treatment has been constructed at tfe
Big Five Tunnel. The pilot plant has been constructed to determine the
ability of passive-treatment effluent to meet upstream levels for the
discharge from a treatment facility at the end of the facility discharge
pipe. The pilot plant vill also be operated to gather design data for
sizing volume requirements, determine optimum dissolved and suspended me'al
removal for various organic and vegetation types and confirm re^o.al
-3-

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TABLE 1
DAILY DISCHARGE OF DISSOLVED AND SUSPENDED METALS FROM MINE DRAINAGES


Aquatic
Mean Flow
Metals

Mean Discharge
Life
a
of Discharge
Loading
Parameter
Concentration
AVQC

To Stream
(Total)
Ug/L
yg/L
(cfs) (MGD)
lbs/day
NATIONAL PORTAL




Aluminum
243
150b

0.08
Arsenic
7
190S

0.002
Cadmium
7
0.66

0.002
Chromium
6
7. 2C

0.002
Copper
185
6.5e

0.06
Iron
47,475
j

15.8
Lead
8
1.3

0.002
Manganese
17,625
E

5.9
Nickel
212
88

0.07
Silver
2
1.2*

0.001
Zinc
6,303
47

2.1
Total
72,073

0.06 0.04
24
GREGORY INCLINE




Aluminum
3,288
150

7.2
Arsenic
5
190

0.01
Cadmium
11
0.66

0.02
Chromium
8
7.2

0.02
Copper
879
6.5

1.9
Iron
138,333
-

300.0
Lead
20
1.3

0.04
Manganese
27,950
-

59.4
Nickel
192
88

0.4
Silver
3
1.2

0.01
Zinc
6,315
47

13.7
Total
176,977

0.40 0.26
383

-------

TABLE
1 (Cone.)


DAILY DISCHARGE
OF DISSOLVED AND
SUSPENDED
METALS FROM MINE
DRAINAGES


Aquatic
Mean Flov
Metals

Mean Discharge
Life
A
of Discharge
Loading
Parameter
Concentration
AVQC

To Stream
(Total)
Ug/L
Ug/L
(cfs) (MGD)
lbs/day
QUARTZ HILL




Aluminum
63,400
150

1.5
Arsenic
1,474
190

0.04
Cadmium
363
0.66

0.009
Chromium
56
7.2

0.001
Copper
48,733
6.5

1.2
Iron
549,667
-

13.3
Lead
137
1.3

0.003
Manganese
62,100
-

1.5
Nickel
480
88

0.01
Silver
18
1.2

0.001
Zinc
89,300
47

2.2
Total
815,728

0.004 0.0029
20
ARGO TUNNEL




Aluminum
19,600
150

49.0
Arsenic
135
190

0.3
Cadmium
126
0.66

0.3
Chromium
19
7.2

0.05
Copper
5,170
6.5

13.0
Iron
144,000
-

360.3
Lead
59
1.3

0.2
Manganese
84,050
-

210.3
Nickel
218
88

0.6
Silver
75
1.2

0.2
Zinc
42,375
47

106.0
Total
295,827

0.46 0.3
740
-5-

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TABLE
1 (Cont.)


DAILY DISCHARGE
OF DISSOLVED AND
SUSPENDED
METALS FROM MINE
DRAINAGES


Aquatic
Mean Flow
Metals

Mean Discharge
Life
of Discharge
Loading
Parameter
Concentration
AVQC

To Stream
(Total)
lig/L
vg/i
(cfs) (MGD)
lbs/day
BIG FIVE




Aluminum
14,067
150

3.4
Arsenic
8
190

0.002
Cadmium
27
0.66

0.007
Chromium
14
7.2

0.003
Copper
1,420
6.5

0.3
Iron
51,000
-

12.3
Lead
40
1.3

0.01
Manganese
28,733
-

6.9
Nickel
239
88

0.06
Silver
6
1.2

0.002
Zinc
8,253
47

2.0
Total
103,807

0.045 0.029
25
? AVQC - Ambient Water Quality Criteria (Clean Water Act).
See Fed. Reg. Vol. 51, No. 47, March 11, 1986, p. 8362.
' See Fed. Reg. Vol. 50, No. 145, July 29, 1985.
AVQC for Cadmium, EPA 440/5-84/032, January 1985.
x AVQC for Copper, EPA 440/5-84-031, January 1985.
AVQC for Lead, EPA 440/5-84/027, January 1985.
? See Fed. Reg. Vol. 45, No. 231, November 28, 1980, p. 79340.
See Fed. Reg. Vol. 51, No. 102, May 28, 1986, p. 19269.

-------
deteriorated crib retaining vail and decreased the slope of the tailings
pile to stabilize it. EPA then constructed a temporary gabion-basket
retaining vail.
Surface vater contamination results from lov pH mine discharges emanating
from the five tunnels and from seepage of ground vater through tailings
piles both proximal to these tunnels and along stream courses. The lov pH
mine discharges results in the degradation of vater quality and aquatic
habitat. Data gathered during the Remedial Investigation has shovn that:
o Runoff from tailings and vaste rock piles contains dissolved and
suspended metals.
o There are tailings and vaste rock piles adjacent to Clear Creek and
North Clear Creek that are unstable and could collapse into the
creeks. These tailings are acidic in nature. Vhen introduced to
vater, the pH vill rapidly decrease and significant amounts of
dissolved and suspended metals vill be released to the stream.
o Hydrostatic pressure vill build up in the tunnels due to cave-ins.
After sufficient pressure has built up, the tunnels vill blov out,
releasing large volumes of metals to the creeks.
o Ground vater in the vicinity of the tunnels is contaminated.
o There are additional sources of acid mine drainage and tailings
upstream that could be contributing dissolved and suspended metals
to the creeks.
All of the above factors contribute to vater quality and aquatic habitat
degradation and vill be addressed in the folloving subsequent operable
units:
Operable Unit No. Tvo - Tailings and Vaste Rock Remediation
Operable Unit No. Three - Source Control
Operable Unit No. Four - Blovout Control
Operable Unit No. Five - Regional Ground Vater Contamintation
Operable Unit No. Six - Upstream Mine Tunnel Discharges and Tailings
-9-

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Current Site Status
The concentrations of most metals (aluminum, cadmium, copper, lead,
manganese, nickel, silver, and zinc) detected in the mine tunnel discharges
exceed Maximum Contaminant Levels (HCLs) established under the Safe
Drinking Vater Act (SDVA) for drinking vater and Ambient Vater Quality
Criteria (AVQC) established under the Clean Vater Act for protection of
aquatic life. In several instances, the AVQC for protection of aquatic
life are exceeded in the mine tunnel discharges by more than tvo orders of
magnitude. Conversely, with respect to the HCLs for drinking vater, the
respective dissolved and suspended metal concentrations in Clear Creek and
North Clear Creek are often within the established criteria. It is
important to emphasize, hovever, that most dissolved and suspended metal
concentrations in the receiving streams exceed AVQC for protection of
aquatic life, which are more stringent than MCLs for drinking vater for
these particular contaminants of concern. Table 1 is a computation of the
daily loading of dissolved and suspended metals in the mine discharges from
each of the five mine tunnels in the study and compares mean discharge
concentrations to AVQC.
A public health evaluation vas conducted to identify compounds vhich could
pose a significant health threat. All available data from surface vater
and ground vater sampling and tailings/vaste rock analyses were evaluated.
Results indicate that of the elements detected, there vere 10 contaminants
of primary concern due to their widespread extent, potential health and
environmental effects, and relative concentration. The contaminants of
concern vere identified as aluminum, arsenic, cadmium, chromium, copper,
fluoride, lead, manganese, nickel, silver, and zinc.
The public health evaluation assessed the following risks associated with
exposure to surface vater from ingestion and direct contact by humans and
aquatic life. The results of the public health evaluation follow and are
summarized in Table 3.
-10-

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TA3L£ 5
COST SUMMARY
Cost Estimates	Present Vorth at
(31,000)	Discount Race (Si,000)
Alternative	Capital Annual 0&M	10%
1. No Action
33
-
-
2. Passive Treatment
1,663
115
2,549
3. Accive Treatment
2,275
549
7,732
4. Passive Treatment and
3,864
511
8,967
Active Treatment
Combination
-30-

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Clear Creek/Central City Site
Mining Waste NPL Site Summary Report
Reference 2
Excerpts From Clear Creek Phase II Remedial Investigation Report,
Volume 1 - Text - DRAFT; Camp, Dresser & McKee;
April 1990

-------
DRAFT
CLEAR CREEK
PHASE II
REMEDIAL
INVESTIGATION
REPORT
VOLUME 1
TEXT
Camp Dresser & McKee Inc
APRIL 1990

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1 0 INTRODUCTION
1.1 Rl/FS STATUS
Past mining activities have resulted in the historic as well as current discharge of acid mine drainage
containing elevated concentrations of metals into Clear Creek and North and West Forks of Clear Creek.
In 1982, the Clear Creek/Central City site was ranked as Site No. 174 on the Interim National Priority
List (NPL) of 400 sites and placed in the final NPL in September 1983.
In 198S a Remedial Investigation and Feasibility Study (RI/FS) was initiated under the direction of Region
8 of the U.S. Environmental Protection Agency (EPA). The Remedial Investigation Report and
Feasibility Study Report (CDM, 1987a) were completed and released for public comment in June 1987.
The RI focused on discharges and milling and mining wastes from five mines/tunnels (Big Five and Argo
Tunnels near Idaho Springs, Quartz Hill Tunnel west of Central City, and the Gregory Incline and
National Tunnel near Black Hawk). The parameters of concern which were identified included
aluminum, arsenic, cadmium, chromium, copper, fluoride, lead, manganese, nickel, silver, zinc, and pH
Remediation at the site was divided into three operable units (OUs). Feasibility studies were completed
for each of the operable units (OU) to evaluate treatment of mine discharges (OU1, CDM 1987b),
remediation of tailings and waste rock (OU2, CDM 1987c), and control of discharges from the Argo
Tunnel (OU3, CDM 1988b). To complete the FSs, additional investigations had to be performed,
particularly inside of the Argo Tunnel and at the Big Five site. The results of these investigations are
contained in two RI Addenda (CDM, 1988a and CDM, 1988c). The June 1987 RI, the two RI Addenda,
and the three FSs are collectively termed the Phase I Studies. The Phase I studies were restricted to the
area of the five mines/tunnels listed previously. Records of Decision (ROD) were signed for both
Operable Units One and Two in September 1987 and March 1988, respectively. During review of
Operable Unit Three FS, the State officially requested that the Record of Decision (ROD) be postponed
until an upstream RI (Phase II RI) was completed. The overall purpose of the Phase II studies was to
evaluate additional sources of stream contamination and its associated impact so that a more
comprehensive basin-wide remediation plan could be developed. Responsibility for design of treatment
of mine discharges (Operable Unit One) and the Phase II investigations of additional sources was
transferred from EPA to the Colorado Department of Health (CDH) in June 1988. Work commenced
1-1

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elevations which begin to melt earlier than the higher elevation areas draining to the Lawson gage. The
initial peak flows at the Golden gage are a result of snowmelt from these lower elevation areas in the
watershed, flows remain at peak levels for about 2 weeks as snowmelt continues at the higher elevations
From September through November, streamflow gradually declines to baseflow conditions in the range
of 40-55 cfs, remaining fairly regular until the next snowmelt season.
4 2 2 SUMMARY OF EPA WATER QUALITY/TOXICOLOGICAL FALL 1988 SAMPLING
The EPA conducted a fall sampling program at the Clear Creek/Central City site in September 1988 to
determine the ecotoxicity of mine waste contaminants to resident aquatic communities in Clear Creek and
North Clear Creek (EPA 1988). The fall sampling was later supplemented with the toxicological
sampling program conducted in 1989 as part of this Phase II RI (see Section 4.5). To assess ecotoxicity,
samples of water quality, sediments and benthic macro invertebrates were collected in the Fall 1988
program upstream and downstream of the major tunnel discharges in Clear Creek and North Clear Creek.
These included the Big Five and Argo Tunnels on Clear Creek and the National and Quartz Hill Tunnels,
Gregory Incline, and Gregory Gulch on North Clear Creek Sample locations and numbers used in the
Fall 1988 program are identical to those in the Phase II RI program, and may be found on Plate IV, EPA
lab analyses are discussed in Section 4 5.1. Analytical data for surface water and sediment quality are
presented in Appendix 4B Results of the macroinvertebrate sampling are discussed in Section 6 0.
4 2 2 1 Water Quality Results
Three major point sources were identified for Clear Creek in the EPA study; the Big Five and Argo
Tunnels and North Clear Creek. The Argo Tunnel, consistent with results from the Phase I RI,
represented the largest contributor of metals to Clear Creek of all three sources as evidenced by the
proportional increase in metals concentrations downstream of this discharge. The dominant metals in both
tunnel discharges were iron, manganese, zinc and aluminum in that order primarily in the dissolved
phase. The discharges were also characterized by low pH and dissolved oxygen concentrations. Within
Clear Creek, the order of dominance of metals in terms of concentrations was manganese (dissolved),
fluoride, and iron (predominantly in the particulate fraction) with lesser amounts of aluminum, copper
and zinc. Metals were primarily in the dissolved phase upstream of the Argo and reversed to the
particulate phase downstream of the Argo on Clear Creek. The sampling site upstream of Idaho Springs,
4-5

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CLEAR CREEK NEAR LAWSON
USGS GAGING STATION 06716500
Oi	0101	03 01	05.01	07/01	09'0i
AVERAGE FOR PERIOD OF RECORD 1946-1986
CLEAR CREEK AT GOLDEN
USGS GAGING STATION 06719505
900
8001
700-
,0/01	12.01	02 01	04/01	06/01	00/01
1 1/01	01/01	03 01	05/01	07,01	09 01
AVERAGE FOR PERIOD OF RECORD 1976-1989
Figure 4-1 Average Daily Streamflow Hydrographs for Period of Record
at Lawson and Golden Gaging Stations.

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taken as a reference point, also showed elevated levels of metals indicating sources upstream of the study
area
On North Clear Creek, point sources were identified as the National and Quartz Hill Tunnels and the
Gregory Incline and Gregory Gulch. Consistent with discharges on Clear Creek, metals in these
discharges were primarily in the dissolved phase and were predominantly iron, manganese, and zinc
The relative contribution of manganese and zinc, as well as aluminum and copper, varied with the source.
Stream quality in North Clear Creek resembled the tunnel discharges quality with iron, manganese, and
zinc in the dissolved phase and aluminum in the particulate phase constituting the predominant metals
Also detected throughout the study area and in higher concentrations than on Clear Creek were copper,
lead and nickel Fluoride was the only parameter found in higher concentrations on Clear Creek than
on North Clear Creek. Of the above metals, only aluminum, copper, iron, and zinc were detected in
North Clear Creek upstream of Black Hawk, though at order of magnitude lower levels than North Clear
Creek sites downstream of Black Hawk. Metal concentrations were elevated in North Clear Creek from
the Gregory Incline to the confluence with Clear Creek, an indication of the poor ability of the creek to
attenuate the inorganic contaminants.
Both the Gregory Incline and National Tunnel were identified as the greatest contributors of metals in
North Clear Creek. Upon passing the Gregory Incline, the metal phase changed from the paniculate
phase to a predominantly dissolved phase. The percentage of metals in the particulate phase increased
in the downstream direction but did not exceed the percentage in the dissolved phase until reaching the
confluence with Clear Creek.
Trends in sediment metals concentrations varied between Clear Creek and North Clear Creek. In both
creeks, the predominant metals in sediments were iron and aluminum, in that order. Also dominant on
Clear Creek though detected on North Clear Creek were manganese and zinc. The metals arsenic,
cadmium, chromium, copper, lead, and nickel were detected on both creeks in all sediment samples. On
Clear Creek, sediment metals concentrations increased in a downstream direction for all metals except
manganese. Downstream of the confluence with North Clear Creek on Clear Creek the total metal
burden in sediments increased by 100 percent. On North Clear Creek the sediment metal burden was
greatest just below the Gregory Incline, due primarily to the high concentration of iron, and remained
high until the confluence with Clear Creek. Both copper and manganese sediment concentrations
increased consistently in the downstream direction. Aluminum, arsenic, chromium, iron, nickel, and zinc
4-6

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result, only flows below approximately 1 5 cubic feet per second (cfs) were measured. The measured
flows are presented in Table 4-5.
4 3 2 SCREENING SURVEY RESULTS
North Clear Creek contained zinc up to 15 mg/L in the main channel (SS-07, 5 miles above the
confluence with Clear Creek), which decreased to 0 08 mg/L at the confluence with Clear Creek. High
concentrations of zinc were identified in Gregory Gulch (2.15 mg/L), Chase Gulch (0.7 mg/L), Quartz
Hill drainage (0 85 mg/L), and Russell Gulch (0 9 mg/L). Addition of terpyridine in the field showed
that samples collected from North Clear Creek between Smith Hill (5 miles upstream of Clear Creek) and
Chase Gulch (8 miles upstream of Clear Creek) contained dissolved ferrous iron in excess of 1 mg/L,
indicating that acid water had recently entered the stream. A potential background sample was collected
near the headwaters of Eureka Gulch (SS-89). This area did not show significant mining activity, but
approximately 50 yards above the sampling point two exploration pits were found which contained pyrite,
chalcopyrite, vuggy quartz infills, and galena, indicative of local mineralization in the area The zinc
concentration in Eureka Gulch was <0 01 mg/L, ferrous iron was 0.91 mg/L, and the pH was 6.8.
Chicago Creek and its major tributaries were sampled between Clear Creek and Ute Creek. All samples
were below 0.02 mg/L zinc.
The West Fork of Clear Creek was impacted by acidic drainage entering at Lion Creek (pH = 3 6)
containing 0 6 mg/L zinc. The highest zinc concentration entering the West Fork of Clear Creek was
from Woods Creek (0 98 mg/L). This concentration was diluted during passage along the West Fork
with zinc concentrations decreasing to 0 12 mg/L just above the confluence with Clear Creek.
The Clear Creek mainstem showed an unexplained increase in zinc between Silver Plume and the
Georgetown Lake, where the concentration increased from 0.02 mg/L to 0.06 mg/L. The additional zinc
loading could be the result of a non-point source such as ground water discharge to Clear Creek. There
was no detectable change in Clear Creek zinc concentrations from either the West Fork of Clear Creek
or North Clear Creek. The most significant increase in Clear Creek zinc concentrations was found at
Idaho Springs where the concentration increased from 0.03 mg/L above the Big Five Tunnel to 0 2 mg/L
below Idaho Springs due to Big Five and Argo discharges and Virginia Canyon underflow. Zinc
4-16

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TABLE 4-6
COMPARISON OF FIELD FILTERED AND LABORATORY SAMPLES
Sample	Zuic fmg/L)	Ferrous Iron fmc/L)
(#)	Field Laboratory	Field Laboratory
Filter Filter	Filter Filter
SS-32	1.70 1 80	<0 2 1.0
SS-49	3 40 3 50	2 6	2.8
SS-110	0.18 0 15	4 07 3 03

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concentrations decreased from Idaho Springs down to Golden, where the level was measured at 0 08 mgI
L.
44 PHASE II RI HIGH AND LOW FLOW SAMPLING PROGRAM
The goal of the high and low flow sampling sessions was to describe the Clear Creek drainage in terms
of volumetric flow rates and metal concentrations under both high and low flow conditions. The results
of the chemical and physical water quality measurements made during the two sampling sessions were
used to determine the type and extent of contamination, to characterize spatial variability in the surface
water chemistry, and as data for the hydrodynamic computer model used to predict the fate and transport
of metals in the Clear Creek drainage.
The surface water sampling for total and dissolved constituents was done in close coordination with
EPA's toxicity studies (discussed in Section 4.5). In a coordinated effort to save time, several samples
for the EPA analysis were collected by the CDM team during their regular sampling schedule A key
objective was therefore to ensure that water samples for chemical analysis and toxicity studies were
obtained at the same time and location to maximize data interpretability.
The level of detail for field work was chosen to provide the most cost-effective analysis of loadings into
Clear Creek. Specifically, the CDM team evaluated loadings from tributaries as they enter the main
drainages rather than sources more remote from the mainstem. Additional site-specific sampling may be
undertaken in the FS stage if it is shown conclusively that specific drainages with unknown point sources
are negatively impacting the mainstems.
4 4 1 HIGH AND LOW FLOW SAMPLING METHODOLOGY
In order to bracket thft anticipated range of annual variability in metal concentrations, two sampling
sessions were conducted: one during high flow conditions (June 12-19, 1989) representing maximum
dilution effects, and one during low flow (September 18-21, 1989) representing minimum dilution.
4-17

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4 4 11 Sampling Locations
Tables 4-7 and 4-8 summarize the high and low flow sampling, respectively, showing sample locations,
what sampling was conducted, and by which laboratory the chemical analyses were performed. Surface
water sites for high and low flow are located within the basin on Plate IV.
Originally in the Phase II RI, 25 sites were to be selected for water quality sampling. However, based
on the review of the Screening Study results and requirements of the EPA toxicological program, a total
of 50 initial sites were selected for the water quality program To offset the cost of additional laboratory
analyses, it was agreed by mutual consent of CDH, EPA, and the CDM team, that EPA would perform
the analytical work on selected sites. In exchange, the CDM team collected water samples and took flow
measurements for EPA at the sites for toxicological sampling indicated in Tables 4-7 and 4-8. Sampling
locations for toxicity testing are discussed in Section 4.5.1.
Several sites were selected to correspond to the mountain community raw surface water intakes. These
include Chicago Creek for Idaho Springs (SW-08) South Fork Clear Creek for Georgetown (SW-25),
Mad Creek for Empire (SW-32), and North Clear Creek for Black Hawk (SW-48). Treated water
supplies are analyzed for inorganics, organics, and radioactivity every 1, 3, and 4 years, respectively (see
Section 4 2 6), as part of the Colorado Primary Drinking Water Regulations. At the Gregory Incline
(SW-46), sampling for water quality, toxicity studies, and flows were to have taken place on seepage
from the Incline. Seepage may have been discharging below the stream water surface, but none was
visible during the high flow period, thus this site was not sampled in the spring. During the low flow
sampling, this site was sampled but flow was not measurable.
Surface water sites SW-16 and SW-19 at the headwaters of Fall River and North Spring Gulch
represented background levels in mineralized zones. They were selected because of their proximity to
an exposed mineralized area which was not affected by mining activity. However, at site SW-19, a small
mine was located up-slope from the sampling point which may affect the water quality.
The low flow sampling program was expanded over the high flow sampling program in terms of number
of flow measurements, number of sampling locations, and extent of definitive toxicological testing
(discussed in Section 4.5.1). During high runoff, only 20 percent of the Clear Creek mainstem flows
were measured due to streams which were too high to safely wade. On the West Fork of Clear Creek
4-18

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On Clear Creek, concentrations and loadings are apparendy quite different below the Argo Tunnel
between Phase I and Phase II. Both high and low flow zinc concentrations were less during the Phase
I sampling than during Phase II, resulting in lower zinc loadings (where flow measurements were avail-
able). Extreme variability obviously occurs in the vicinity of the Argo Tunnel. In the Phase I study,
numerous samples were taken along approximately 14-mile of the reach below the Argo; it was found that
total zinc concentrations varied from 37,800 iiglL to 2,710 \iglL in the reach below the tunnel The
Phase I and Phase II sampling sites did not exactly match in this area; due to the potential for non-point
loading and coprecipitation which may be occurring (as discussed previously) and the variability observed
in Phase I, a small difference in locations can significantly affect results. At the other sites along Clear
Creek, Phase I and Phase II results are more similar than in the area of the Argo, but it does appear that
concentrations and loadings during Phase II were generally lower than previously observed.
4 8 13 Comparison of AMAX and Phase II Water Quality Data
The AMAX (1989) NPDES data for the Henderson/Urad Mine (Section 4.2.4) provides a 10-year record
of water quality data along West Fork Clear Creek with which to compare the Phase II results. Table
4-34 presents statistics of selected metals from the AMAX data compared to the high and low flow
sampling data from Phase II.
All Phase II values fall within the ranges of values observed in the AMAX database, with the exception
of total aluminum during high flow on Woods Creek (2 28 mg/L in Phase II compared to a maximum
value of 2.22 mg/L from the database). Phase II metal concentrations along the West Fork above Woods
Creek were generally lower than average AMAX values. Woods Creek and the West Fork below Woods
Creek sites had concentrations in Phase II which were typically greater than or equal to average AMAX
values
4 8 2 SURFACE WATER INVESTIGATION RESULTS SUMMARY
The Screening Survey resulted in an initial identification of potential sources of contamination which was
then used to select the sampling sites for the High and Low Flow and Toxicological Programs. The
Intermediate Flow Sampling Program was conducted to provide additional data for verification of the
WASP4 modeling effort (Section 10.0) by correlating streamflows and zinc concentrations under non-
extreme flow conditions; however, the results of the program were not useful for the modeling due to
4-72

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TABLE 4-33
COMPARISON OF PHASE I AND PHASE II ZINC CONCENTRATIONS AND LOADINGS
FOR CLEAR CREEK AND NORTH CLEAR CREEK



Jul 83
 1 jxad
(IbMav)
Clear Creek


















sw »
SW 13
Ckv Creek Upurcini of Five Tunnel

-


2U&0


12600


174 0
-
-
1*0

6-5 0
L300
807
SW 12
SW-01
Clear Citck Upal/eam of As go Tunnd
-
16*0

710
25&0
9&8
35 4
354,0
6&0

2240
-

2100

1110
407 0
243 7
S.W 21
SW44
Clew Cntk Downstream of A/jo Twmd

6J9 0

77 S
2090.0
8730
-
2S000


801 0
-

2*10

ItiOO
760 0
4100
SW-01
SW -03
Qear Crtd Upurcaa of North Clear Creek
-
2140

77 2
4490
1870
-
8490

-
16000
-

2J0.9

1100
664 0
394 1
SW42
SW-02
dear Creek Dowru-lream of North CVir Crrek

2440

74 ft
54/0
2207
313
793 0
1339
SM0
525 0
imd i
-
1300
-
loro
3410
19*6
North Clear Creek


















SW II
SW-48
North Clear Creek at Black Hawk Inukc
47
2*8.0
93
2.6
)M0
79
14
7/&0

48.3
90
i)
I*/
33 0
48
1 9
|/70
1 6
SW 10
SW 45
North Clear Creek Dovruiream of Gregory Inefene
M
5070
22.0
2./
11800
171
-
16400


HO

37 S
630
13 2
10
moo
12.9
SW4V
sw-o
North Clear Creek Dovtmnaa of Gregory Gukh
7*
5*5 0
132
32
11800
204
-
IB400

-
1490
-
31 8
320 0
549
2.8
13)0.0
19 7
SW41
SW-40
North Clear Creek Dmruiniffl of Nauonat Tunnel
&7
1330
B 1
J I
12*00
20 J
12
I670l0
2! 8

403 0
-
3/3
ISOlO
302
30
2060 0
33 2
SW-03
SWM
North Clear Creek Upctrcamof Clear Crerk
ioi
5S2.0
31 3
4*
14000
J&9
-
14400


47S0
-
&46
isao
M0
33
22200
39 0

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the poor correlations and associated uncertainties,
tasks are as follows:
High and Low Flow Sampling Program
The major conclusions from the remaining Phase II
•	The sampling efforts were conducted in a "below-average" runoff year. Average Clear Creek
streamflows during Water Year 1989 were 83 percent of normal at Lawson and 78 percent
of norma] at Golden. This may have resulted in observed contaminant concentrations which
were greater than those which would have been observed during an average runoff year, but
mass loadings may have been less than average due to the lower flow volumes.
•	Dissolved zinc concentrations sampled during high and low flows consistently exceeded
existing, acute, and chronic water quality standards throughout the Clear Creek basin
Dissolved cadmium, total manganese, and dissolved copper standards were frequently
exceeded along specific stream segments.
•	With the exception of aluminum and iron as noted below, precipitation of metals could not
be predicted with the MINTEQ2A model, though the possibility exists that they may be
removed with iron or aluminum precipitations via adsorption or coprecipitation.
Clear Creek Mainstem
•	Dissolved zinc concentrations and total zinc loadings increased in Clear Creek downstream
of the Silver Plume area, though the increases were more significant during low flow than
high flow. Concentrations and loadings of other constituents did not change appreciably in
this area during high flow, although slight increases in sulfate, dissolved iron, and manganese
concentrations were observed during low flow. The Burleigh Tunnel was identified as one
source of zinc loading, but non-point loading of total zinc in this area was also significant
during both high and low flows.
•	Zinc loading significantly decreased below Georgetown Lake during low flow, possibly due
to a combination of settling and adsorption in the lake.
•	West Fork Clear Creek had a much larger impact on Clear during high flow than during low
flow. Dissolved zinc, sulfate, and manganese concentrations increased in Clear Creek below
the West Fork during high flow. Relatively minor increases in dissolved zinc, sulfate, and
dissolved iron concentrations were observed downstream of the West Fork during low flow.
Total iron concentrations decreased significantly and manganese concentrations increased
significantly during low flow below the West Fork.
•	Dissolved zinc, dissolved iron, sulfate, and manganese concentrations increased in Clear
Creek through the Idaho Springs area during high flow. The same was true during low flow,
except that dissolved iron decreased while total iron increased. The Big Five Tunnel had no
measurable impact on Clear Creek during high flow, but did cause an increase in zinc
concentrations during low flow. Argo Tunnel discharges increased dissolved and total iron
and total zinc concentrations in Clear Creek during high and low flows. Dilution by Chicago
Creek results in a decrease in sulfate and manganese between the Big Five and Argo Tunnels.
4-73

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TABLE 404
COMPARISON OF SELECTED WATER QUALITY DATA FROM
THE HENDERSON/URAD MINE VND PHASE II RI

Phase



Total Metal Concentration (mg'L)

Urad
II Rl
Site

Urad Samolme Proaram
Phase II Rl
Site
Site
Description
Parameter
Minimum
Maximum
Average
High Flow
Low Flow
HE-3
SW-35
West Fork
Aluminum
0 05
1 20
0 14
.. ..
0 05


Clear Creek
Above Woods
Iron
0 04
1 90
0 20

0 085


Creek
Lead
0 0002
0 0140
0 0026

<0 001



Manganese
0 05
0 95
0 16

0 114



Molybdenum








Zinc
001
0 10
0 03

0 027
U-2
SW-34
Woods Creek
Aluminum
0 05
2 22
0 61
IsJ
1J
CO
1 30



Iron
0 05
3 00
040
1 460
0 817



Lead
0 001
0040
0 005
<0 005
<0001



Manganese
0 25
26 00
8 98
7 53
16 40



Molybdenum
0 01
3 20
0 26
0 053
0 088



Zinc
0 05
2 30
0 83
1 41
1 76
U-l
SW-54
West Fork
Aluminum
0 05
1 85
0 49

0 606


Clear Creek
Below Woods
Iron
0 05
3 20
0 28

0 226


Creek
Lead
0 001
0 009
0 002

<0 001



Manganese
0 15
16 90
6 16

10 00



Molybdenum
0 01
13 60
0 44





Zinc
0 05
1 70
0 54

0 998
S-l
SW-29
West Fork
Aluminum
0 10
I 75
0 38
0 538
0 369


Clear Creek
Above Clear
Iron
0 05
2 40
0 45
0 443
0 916


Creek
Lead
0 001
0 009
0 002
<0 005
<0 001



Manganew
0 02
5 45
I 97
1 66
2 7J



Molybdenum
0 01
0 10
004
0 017
0 021



Zinc
0 05
0 45
0 18
0 306
0 249

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Non-point loading may be significant between the Big Five and Argo Tunnels, particularly
during low flow
•	North Clear Creek had a relatively minor impact on Clear Creek water quality during both
high and low flow due to its small volumetric flow
West Fork Clear Creek
•	Loading of metals was dominated by Woods Creek during high flow. With the exception of
magnesium, most constituents that enter the West Fork from Woods Creek were still present
at the mouth of the West Fork Concentrations tended to decrease along the West Fork as
a function of distance from Woods Creek, primarily due to dilution.
•	The West Fork was primarily impacted by Woods Creek during low flow, with increases in
dissolved zinc, sulfate, manganese, and dissolved aluminum below Woods Creek Dissolved
iron decreased below Woods Creek, probably due to a combination of precipitation and
dilution Slight increases in dissolved aluminum, iron, and sulfate concentrations were
observed below Lions Creek
•	Total zinc loading in the West Fork decreased by 46 percent from Woods Creek to Lion
Creek, possibly by coprecipitation with iron or aluminum hydroxides.
•	Visual and chemical evidence indicates that aluminum precipitates in Woods Creek, probably
as a hydroxide. Additionally, aluminum and iron minerals may be precipitating in the West
Fork, but visual or mineralogic data do not exist to verify this.
North Clear Creek
•	Chase Gulch, Gregory Gulch, ant the Gregory Incline had the most significant impacts on
concentrations and loadings in North Clear Creek, with Gregory Gulch being the single
largest source of metals during high flow Affected constituents include dissolved zinc,
dissolved manganese, and sulfate. High flow impacts from other point sources were
statistically insignificant.
•	The Gregory Incline dominated loading and caused increases in concentrations for the same
constituents during low flow; significant increases in dissolved iron and total aluminum were
also observed. Non-point zinc loading may be occurring in North Clear Creek downstream
of the National Tunnel.
•	Total and dissolved iron concentrations decreased in North Clear Creek below Black Hawk
Previous Screening Survey results and low flow mass balances indicate that much of the iron
was deposited in the channel through precipitation of amorphous ferric hydroxide. Visual
and chemical evidence also indicates that iron is precipitating in North Clear Creek
Additionally, aluminum may be precipitating in North Clear Creek, but visual or mineralogic
data do not exist to verify this.
4-74

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Trixicological Program
•	Instream toxicity to test organisms was less during low flow than during high flow throughout
the basin, with the exceptions of North Clear Creek, where instream conditions were acutely
toxic to both organisms, and downstream of Idaho Springs on Clear Creek, where fathead
minnows were more sensitive to instream conditions during low flow than high flow.
Decreased toxicity results in low flow may be due to high hardness values (in comparison to
high flow hardness). The exceptions may be due to higher metals concentrations in the
streams during low flow.
•	Acutely toxic instream conditions were found throughout the basin for both Cenodaphnia and
fathead minnows during high flows. Overall, Cenodaphnia was the most sensitive test
organism, except in North Clear Creek where the increased sensitivity of fathead minnows
may be due to high dissolved iron and other heavy metals concentrations.
•	High flow discharges from the Burleigh, Rockford, Big Five, Argo, Quartz Hill, and
National Tunnels were all acutely toxic to both organisms, with Cenodaphnia being the most
sensitive. During high flow, Cenodaphnia mortalities increased within Clear Creek
downstream of the tunnels. However, the tunnel discharges did not generally result in
increased fathead minnow mortalities in Clear Creek.
•	Except for Fall River and Chicago Creek, most major tributaries to Clear Creek were acutely
toxic to both test organisms. Trail Creek was extremely toxic.
•	The stream profile for Clear Creek during high flow conditions showed a reduction in toxicity
to fathead minnows in a downstream direction from the headwaters to Golden (except for
below the Argo Tunnel where toxicity increased). Cenodaphnia remained acutely sensitive
to instream water quality along the entire mainstem of Clear Creek.
•	During low flow, increased toxicity was observed below Chicago Creek on Clear Creek, but
not above, possibly due to the influence of ground water non-point loading in the area.
Storm Event Sampling Program
•	Storm event water samples typically contained elevated levels of suspended solids and metals
in comparison to the high and low flow samples.
•	The fraction of zinc present in the solid phase generally tended to be higher during storm
events.
•	Large variabilities in terms of total loading and metal partitioning were observed between
storm events.
•	Toxicity to test organisms did not increase in North Clear Creek upstream of Chase Gulch
during a storm event in comparison to the high and low flow sampling; however, toxicity
increased dramatically during the same storm on North Clear Creek below Gregory Gulch
Total and dissolved metals were also often higher at North Clear Creek sites during the storm
than during high and low flows, though this was not always the case. Increased toxicities
4-75

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were also observed all along the North Clear Creek mainstem and from two samples collected
on Clear Creek above and below North Clear Creek.
4.8.3 COMPARISON OF WATER QUALITY EXCEEDANCES TO TOXICITY RESULTS
The data obtained from toxicity testing can be used to evaluate the appropriateness of any remedial
alternative being considered for implementation. The data may also serve as a baseline to measure the
effectiveness of any remedial action which takes place at the site in the future. The toxicity data can be
used, along with the water chemistry data collected to establish site-specific clean-up goals. Traditional
sole reliance upon the chemical characteristics of a stream to set clean-up criteria does not adequately
allow one to quantify that particular stream's use attainability or for the potential restoration of the
affected resource.
Comparing the water quality standards exceedances observed with the Phase II sampling results to the
toxicological data along various stream segments provides insight into the relationships between the results
of these investigations and the contaminants which most significantly impact aquatic toxicity. Table 4-35
compares the major water quality exceedances and corresponding toxicity results (for all applicable
samples) for the 11 Clear Creek basin stream segments (as described in Section 4.4.5). Exceedances of
the acute water quality standards for all segments is most prevalent for dissolved zinc, copper, cadmium,
and total manganese. The stream standards for these metals were exceeded more often during the low
flow than high flow period. However, Ceriodaphnia mortalities of 90 percent or greater were observed
more than 65 percent of the time during high flow, compared to 38 percent of the time during low flow,
possibly due to the generally higher hardness values observed during the Fall.
The toxicological data shows that when the acute stream standards for zinc, copper, and cadmium are
consistently exceeded (greater than 50 percent of the tune), there will be some instream toxicity to aquatic
organisms. The high levels of zinc in the mainstem of Clear Creek had the greatest toxic affect to
Ceriodaphnia. The stream standard for zinc was consistendy exceeded in Segments 2 (Silverplume to
Argo Tunnel) and 11 (Argo Tunnel to Golden) of Clear Creek. The toxicological data show that
Ceriodaphnia may be more sensitive to the zinc concentrations in Clear Creek in comparison to the
fathead minnow. The zinc standards in these mainstem segments are based upon a cold-water fishery
(e.g., trout), whereas warm-water fish (e.g., fathead minnow) can tolerate the higher zinc concentrations
found along the Clear Creek mainstem below Silverplume to Golden. The acute stream standards for zinc
4-76

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Table 4-35: COMPARISON OF WATER QUALITY STANDARDS TO TOXICOLOGICAL DATA FOR THE CLERAR CREEK BASIN

Percent Exceedence of
Acute Stream Standards
Acute Toxicological
Test Results
Site Description
Stream
Segment
Flow
Regime
Zn
Cu
Cd
Afl
Pb
Fathead Minnow
% Mortalities for
All Samples in
Segment
Ceriodaphnia
% Mortalities
for All Samples
in Segment
Stream Segment in
which Toxicological
Tests were Conducted
i
Low
50
0
0
0
0
0
0
Mainsiem Clear Cr from source
lo (he 1-70 bridge above
Stlverplume
High
50
0
0
0
0
0
25
2
Low
1.00
20
1 0
0
0
25,5.0,10,3,66
90,60,5,35.100,
100 100 fiO
Mainsiem ol Clear Cr from the
1-70 Bridge above Silver Plume
lo Ihe Argo Tunnell discharge
High
92
8
8
0
0
3,13.0,20,7.7
95,100,95,60,
30.65
3
Low
0
0
0
0
0
7
0
Mainstem of South Clear Cr
Hiqh
0
0
0
0
0
0
40
5
Low
86
0
43
0
0
13,77,0,85,15
38,90,50,100,65
Mainsiem of W Clear Cr from
Woods Cr to confluence with
Clear Cr
High
100
0
1 00
0
0
59,80,100
100,100,100
7
Low
100
0
0
0
0
45
1 00
Mainstem of Woods Cr from
Upper Urad Res lo Conlluence
with W Clear Cr
Hiah
100
0
100
0
0
1 00
1 00
8
Low
100
1 00
0
0
0
100
100
Mainstem ol Lion Cr trom the
source wiih W Clear Cr
Hiah
100
1 00
0
0
0
100
1 00
9
Low
50
0
0
0
0
1 0
0
Mainstem of Ihe Fall River
Hiah
50
0
0
0
50
1 3
1 0
1 0
Low
50
0
0
0
0
3
0
Mainstem of Chicago Cr
High
50
0
0
0
0
3
0
1 1
Low
100
67
0
0
0
17.3,17.37,0
40,45,90,95,100
Mainsiem ol Clear Cr from
the Argo Tunnel to Golden
Hiah
100
0
0
0
9
0,1 7,10,3,13.40
60,100(4)
1 3
Low
90
70
1 0
0
0
3,100(8)
5,100(8)
Mainstem of N Clear Cr
Hiqh
75
33
8
1 7
8
72,53.38.60,47
100,13.73.10
10,45,10,10,0
100,0, 100.5

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5.0 GROUND WATER INVESTIGATION
The Phase II Remedial Investigation (RI) Report (CDM, April 1987) and Addendum Report (CDM,
January 1988) addressed ground water related to several mining sites within the Clear Creek/Central City
mining district. The scope, methods and results of this initial ground water investigation are summarized
in Section 5.1. Because the RI study area has been expanded to include the entire Clear Creek drainage
basin, a better understanding of ground water is needed to further evaluate sources of contaminants,
mechanisms by which these contaminants move from the ground water to the surface water system, and
the impact that ground water system may have on the nature and extent of contamination within the
surface water system. In addition, more information regarding potential health risks to ground water
users is also needed. As a result, a monitoring well program and domestic well program were
implemented as part of the overall scope of the Phase II RI. Section 5 2 discusses the objectives and
methodologies used in each program. Sections 5 3 and 5.4 discuss the results of the monitoring well
program and domestic well survey, respectively. Section 5.5 summarizes the findings of the ground
water investigation.
5 1 SUMMARY OF PHASE I RI METHODOLOGY AND RESULTS
Ground water sections of the Phase I RI and RI Addendum focused primarily on the following two areas
of concern:
1)	Investigation of ground water hydrogeology and geochemistry associated with five sites
within the study area, namely, the Gregory Incline and Tailings, the National Tunnel, the
Quartz Hill Tunnel, the Big Five Tunnel, and the Argo Tunnel and Mill; and,
2)	Survey of.domestic well water quality including well location/distribution, depths, and use
A summary of objectives, methodologies and results for each of these studies is summarized below

-------
Ground Water
The overall ground water investigation was designed to be limited in scope. The primary objective was
to obtain reconnaissance level data from monitoring wells, most of which were completed as part of the
geotechnical investigation The intended use of the wells was to identify hydrostratigraphic, hydraulic
and geochemical conditions and characteristics at each of the five individual sites and, if necessary,
recommend future RI/FS activities to further characterize the nature and extent of the ground water
systems and the contaminants present within the systems.
A total of 21 monitor wells were drilled and installed within the five site study areas. Drilling and
sampling of the boreholes was conducted in coordination with the geotechnical work. Most (16) of the
wells were drilled with hollow stem auger or some modification such as tricone within the hollow stem
Due to the presence of coarse gravels and cobbles, 5 wells were drilled using cable tool. Well drilling
and completion methods for both auger and cable tool holes can be found in Section 4.6.1 of the Phase
I Rl. Within the Phase I RI and the RI Addendum, geologic/drill logs can be found in Appendix 4A and
A, respectively; well completion information can be found in Table 4-10/Appendix 4D and Table 2-
4/Appendix B, respectively, and well locations/geologic cross-sections can be found within the text of
Sections 7 0 and 2.4, respectively. All the procedures and methods utilized in the drilling program are
summarized in detail within Section 4.6 1 of the Phase I RI.
Upon installation of the monitoring wells, data were collected from each of the wells to generally describe
the ground water aquifer at each site in terms of the following parameters: flow direction, gradient,
hydraulic conductivity, water quality, use and interrelationship between aquifer media and the adjacent
surface water system. Water level and water quality data were generally collected monthly and quarterly,
respectively, for a period of nine months. The only exception to this was regarding the last three wells
completed at the Big Five. Due to access problems which delayed the well installations, these wells were
sampled only once for water quality and measured only three times for water levels over a monitoring
period of five months. Ground water sampling methods are described in detail in Section 4.6.3 of the
Phase I RI.
Aquifer tests were performed on selected monitor wells to estimate horizontal hydraulic conductivity
values. Single well slug tests were performed on a total of 11 wells, with a minimum of one well tested
per site, and a minimum of three hydraulic conductivity values determined per tested well. The
5-2

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5.4 PHASE II RI RESULTS: DOMESTIC WELL SURVEY
The domestic wells which were sampled as part of the RI are listed on Table 5-3. This table summarizes
information regarding the aquifer within which each well is completed, water treatment, water use and
number of users. The locations of the domestic wells are presented on Plate 2.
Approximately nine of the 14 domestic wells which were surveyed service residences having 5 or less
users. The remaining wells included two trailer courts (27 and 100 users, respectively), one subdivision
(100 users), one school (350 users), and one camp (100 users). Owners/users of all the wells sampled
except one (well DW-10) treat their water with some device consisting of a sediment filter, chlorinator,
iron filter, water softener, pH adjuster, or some combination thereof. Table 5-3 lists the particular
treatment device(s) plumbed to each well and notes whether the device was bypassed during the sampling
program. Of the 14 wells sampled, only 6 wells had the water treatment system(s) completely by-passed
for collection of the water quality sample. Because of treatment devices on some of the sampled wells,
caution in interpretation of these data should be exercised. For example, water sampled ftom well DW-
07 had been treated with soda ash for purposes of raising the pH of the water. Because the device was
not able to be readily removed at the time of sampling, the sample was taken subsequent to the pH being
adjusted
5-29

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5.4 1 DOMESTIC WELL WATER QUALITY
Complete water quality analyses for the domestic wells are tabulated in Appendix 1. Values for drinking
water parameters are summarized tn Table 5-15 for each well. Review of the data indicate that water
qualities are extremely variable. For the 6 wells on which no treatment device was used prior to
sampling, general water quality classification ranged from calcium/bicarbonate (2), calcium-
magnesium/bicarbonate (I), calcium/bicarbonate-sulfate (1), calcium/sulfate-bicarbonate (1), and
calcium/sulfate (1) For all domestic wells sampled, total dissolved solids concentrations ranged from
27 mg/1 (DW-11) to 2260 mg/l (DW-07), pH ranged from 3 9 units (DW-01) to 7.75 units (DW-03),
sulfate ranged from 8.8 mg/1 (DW-11) to 1300 mg/1 (DW-07), and zinc concentrations ranged from 8
lig/L (DW-14) to 5560 jig/L (DW-07). If well DW-07 is excluded, all wells exhibited total dissolved
solids concentrations less than 700 mg/1, sulfate concentrations less than 386 mg/1, and zinc
concentrations less than 516 \igil~ The well showing the lowest concentration of total dissolved solids
concentration and most other constituents was DW-11 located near St. Mary's Glacier and background
surface water monitoring station SW-16 on upper Fall River (see Plate 5). Total dissolved solids
concentration for well DW-11 and station SW-16 were 27 and 28 mg/1, respectively. Both of these
waters are extremely similar, showing less than detection limits for most metals and extremely low
concentrations for the other analyzed constituents. Zinc concentrations for DW-11 and SW-16 were also
low at 22 and 10 ng/L, respectively.
5 4 2 COMPARISON TO APPLICABLE WATER QUALITY STANDARDS
For purposes of evaluating potential risk to individuals utilizing ground water within the study area,
domestic well analytical results were compared to primary and secondary drinking water standards (see
Table 5-15). All wells met the primary drinking water standards except DW-07, which had a cadmium
value of 28 ^ig/L compared to the standard of 10 jig/L. The users of this well treat their well water
(Table 5-5) and were notified by letter and telephone of the potential health risk posed by the quality of
their water. As is indicated on Table 5-3, this well water is not used for drinking water purposes.
Compared to secondary drinking water standards, all but four of the wells showed at least one
exceedance. The parameters for which the standards were most commonly exceeded were iron (6
exceedances), manganese (8 exceedances), pH (6 exceedances below pH of 6.5), sulfate (3 exceedances),
and total dissolved solids (4 exceedances). One well, DW-07, exceeded the zinc standard of 5000 ngfL
5-30

-------
with a value of 5560 /xg/L All well users surveyed were sent results of the water quality analyses
including a listing of the primary and secondary drinking water standards.
5.5 GROUND WATER PHASE II RI SUMMARY
The ground water investigation focused on the specified objectives detailed in Section 5 2.1 1, objectives
which were consequential of the Phase I RI conclusions Results ftom the low flow screening study
performed in the early spring of 1989 assisted in identifying three stream segments along which ground
water may play a role in contributing metals to the surface water system. The three segments were in
the following areas: Empire - from above Bard Creek to the POTW; in Idaho Springs - from above the
Big Five Tunnel to below the Argo Tunnel; and, in Black Hawk - from above Chase Gulch to below
National Tunnel. Proximate to these stream segments, ten monitoring wells were installed during the
early fall during base flow conditions, two in the Empire area and the remainder in the areas which had
been studied in the first RI - the Big Five Tunnel, the Argo Tunnel, the Gregory Incline, and the National
Tunnel Ground water data which included water levels and water quality were collected from these 10
wells concurrently (within the same week) with the surface water data which included flow, water quality,
and stream stage relative to ground water piezometric level. Five additional wells were installed in
tailings/waste rock piles (one well per pile), which were considered to be potential sources of metals
contamination contributing to surface water degradation. These areas were as follows: Empire Tailings,
McClelland Tunnel tailings, Golden Gilpin Mill tailings, Boodle Mill tailings, and Gregory Gulch tailings.
Additionally, a water quality survey of 14 private wells was conducted. Nine of the wells were selected
in response to public solicitation and five were selected from Colorado Department of Health listings of
community and non-community water supply systems.
Results of the Phase II Ri are as follows:
o Background water quality is not able to be defined for the study area. Bedrock geology is
extremely variable due to the non-homogeneity of mineralization and faulty fracture systems
throughout the Clear Creek basin. Additionally, subsurface mining-related activities have
radically altered the geochemistry and hydraulics of the bedrock ground water system within
individual mining districts. As a result, application of the term "background water quality",
as used in this study, is restricted to areas relatively free of metals contamination which are
upgradient of areas which are known to be contaminated and potentially impacting the quality
of the surface water system.
5-31

-------
E:\CCRI\CHAP05\TS-_.TBL
TABLE 5-15
COMPARISON OF DRINKING UATER SIANOARDS1 TO DOMESTIC WELL ANALYTICAL RESULTS2-3
Contaminant Priaary Secondary DU-01 DU-02 DU-03 DU-04 DU-05 DU-06 DU-07 DU-08 DU-09 DU-10 DU-11 DU-12 DU-13 DU-U
(Units) Max Level Max Level 10/30/89 10/30/89 10/31/69 11/01/89 11/01/89 11/02/89 11/02/89 11/02/89 11/02/89 11/02/89 11/03/89 11/03/89 11/03/89 11/04/89
Arsenic (ug/l)
50

1.00
UU
1.00
U
1.00
UU
1.00
UU
2.70
UB
7.50
B
1.00
U 1.00
U
1.30
B
1.00
UU
1.00
UU
i.6o e
t.00
U
1.00 u
Cadaiun (ug/l >
10

5.70
S
0.50
U
0.50
U
0.50
U
0.50
u
0.50
u
28.00
ST 0.50
u
0.50
UU


0.50
U
0.50 UU 0.50
u
0.50 U
Chroaiui (ug/l)
50

5.00
u
5.00
U
5.00
U
5.00
u
5.00
U
5.00
u
5.00
5.00
U
5.00
u
5.00
U
5.00
U
5.00 U
5.00
u
5.00 U
lead (ug/l)
50

2.80
UB
1.00
U
1.00
U
1.00
U
1.00
UU
1.00
u
2.00
UU 1.00
U
1.00
U
1.00
U
1.00
UU
1.00 UU 1.00
u
1.00 U
Nitrate (as N)



























(ng/l)
10

1.20
U
2.70

0.80

1.76

1.20
U
1.10

3.00
U 1.80

0.80

4.60

0.60

0.60 U
1.20
u
0.90
Silver (mg/l)
50

0.20
U
0.20
U
0.20
U
0.20
u
0.20
U
0.20

0.20
U 0.20
u
0.20
U
0.20
U
0.20
U
0.20 U
0.20
u
0.20 U
Fluoride (og/l)
4
2
1.80

0.90

0.30

0.60

O.SO

1.80

0.90
0.70

1.80

0.70

0.20

1.60
0.20
B
1.20
Chloride (ng/l)

250
5.00
U
15.40

5.00
U
9.00

5.00
u
25.00

41.00
5.00
u
5.00
U
7.00

5.00
U
8.00
5.00
u
5.00 U
Copper (ug/l)

1000
781.00

4.60
B
1.90
BU
5.60
B
1.00
U
1.00
u
2.70
UB 1.00
u
1.00
U
6.60
B
8.50
UB
1.20 BU 1.00
u
1.00 U
Iron (ug/l)

300
610.00

26.00
US
27.00
B
26.00
U
1020.00
2080.00

7620.00
138.00

62.00
B
59.00
B
34.00
B
11100.00 1
1790.00
204.00
Manganese (ug/l)

50
6550.00

2.00
u
2.00
U
2.00
u
315.00

293.00
18500.00
118.00

27.00

2.00
a
3.00
B
1510.00
153.00
240.00 E
pH. Field (units) 6.5
- 8.5
3.90

6.80

7.75

6.45

7.40

6.35

7.15
7 00

7.10

6.10

7.05

6.25
6.70

6.45
Sulfate (mo/1)

250
364.00

57.00

25.20

38.20

386.00

160.00

1100.00
32.00

77.00

39.00

8.80

210.00
22.00

98.00
Tot. Diss. Solids


























(ng/l)

500
422.00

163.00

191.00

154.00

665.00

673.00

2260.00
274.00

461.00

131.00

27.00

531.00
208.00
254.00
line (ug/l)

5000
516.00

15.00
B
183.00

7.00
B
4.00
B
14.00
B
5560.00
37.00

37.00
B
77.00

22.00

50.00
18.00
B
8.00 B
1 *0 CfR Part 141 Subpart B and Part 143
^ All anions are Total
All aetals are Dissolved
3 values in boldface exceed drinking Mater standards
Lab QuaI iflers:
(U) 3 Not Detected
(U) ¦> Post Dig Spike for GFAA Os Ctrl Lt
(S> » Value Det. by Method of Std Add - MSA
(£) » Value estimated due to interference
(--> = Not analyzed

-------
o Dissolved metals and sulfate load contributions from ground water to surface water with
respect to aluminum, iron, manganese, sulfate, and zinc indicate the total loads contributed
for each study area (see Table 5-7) as follows:
Dissolved Load
in Ibs/dav fAl. Fe. Mn. SO.. Zn^

Per Estimated


Length of
Per Foot of
Studv Area
Affected Channel
Channel
Riverside Park-Argo Tunnel
22,380
8 95
Gregory Incline
4,434
6.33
Big Five Tunnel
2,280
0.57
McClelland Tunnel
2,007
3.35
Gregory Gulch
349
0 70
Above Black Hawk (@ Cty Lmt)
130
0.13
Empire Tailings
108
0 11
o These results indicate that based on the hydrogeologic and geochemical conditions evaluated
at each of the study areas. Riverside Park and the Gregory Incline contribute the largest
quantity of metals to the surface water system. The Big Five Tunnel, the McClelland
Tunnel, and Gregory Gulch also contribute metals but at a significantly lower quantity. At
the Golden Gilpin Mill and National Tunnel area, metals (particularly zinc and manganese)
concentrations are relatively high, but because ground water is apparently not recharging the
surface water system in these areas during low flow conditions, no degradative impacts are
predicted Both the Empire Tailings area and the background location above Black Hawk
at the city limits contribute the least metals to surface water of all the sites studied. The
Boodle Mill Tailings are also contributing metals to the local ground water system, but
because no surface water flow was apparent during low flow conditions and ground water
quality is generally better than at the other tailings/waste rock piles, water quality impacts
are assumed to be negligible relative to the other sites evaluated.
o Water quality of discharges at the McClelland Tunnel, Big Five Tunnel, Argo Tunnel, and
National Tunnel is very similar to ground water quality monitored at each of the sites. At
both the McClelland and Big Five Tunnels, adit discharge is upgradient of wells MW-W04
and BF-01, respectively. Thus, it is possible that the adit discharge acts as a contaminant
source and excerts a degradative influence on the quality of shallow ground water due to
infiltration through tailings/waste rock material on-site. However, at the Argo Tunnel and
National Tunnel sites, the situation is distinctly different in that adit discharge is
downgradient from the bedrock and alluvial well pair, thus not apparently able to influence
upgradient ground water geochemistry. At well MW-A01, upgradient of the Argo Tunnel
adit discharge, alluvial ground water is highly acidic and contaminated with high
concentrations of metals; the source of these metals, if not the Argo Tunnel, is unknown but,
could possibly be influenced by poor ground water quality discharging from Virginia Canyon
Because the vertical hydraulic gradient between the alluvium and bedrock is upwards and
concentrations of most metals are significantly lower in the bedrock than in the alluvium,
bedrock is precluded as a contaminant source. Upgradient of the National Tunnel adit
5-32

-------
discharge, a similar situation is evident. In this case, however, the bedrock ground water
which is flowing upwards into the alluvium is significantly higher in metals concentrations
than the alluvium/waste rock ground water. Thus, bedrock appears to be the source of
metals; the extent of the bedrock contaminant source is unknown
o Bedrock and alluvial ground water in areas which are generally removed from mining areas
is of a quality which usually meets primary drinking water standards but is often deficient
in meeting many secondary drinking water standards, particularly iron, manganese, and pH
These contaminants primarily affect the aesthetic qualities relating to public acceptance of
drinking water. Within areas in which historic mining has occurred, the poorest ground
water may be found. This situation is evident with wells DW-01 and DW-07, located in Lion
Creek Canyon and Virginia Canyon, respectively. Well DW-07 exhibited extremely high
total dissolved solids and metals concentrations while DW-01 exhibited an extremely low pH
and high iron, manganese and zinc concentrations.
5-33

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range has been shown by EPA in several studies to adequately represent breathing zone concentrations
while negating the possibility of vandalism, soil re-entrainment and other anomalies that could skew
results (Fed Reg. 1971).
A subcontractor was hired by the Air Pollution Control Division (APCD) to be the site operator. The
duties of the site operator included filter changes, initial and final flow recordings and problem
identification. This operator received several hours of training by Air Quality Surveillance Section
(AQSS) field technicians. Standard glass fiber filters were used for TSP sampling and quartz filters were
used for PM10 sampling These filters were obtained from the State's EPA supplied ambient network
allocation.
Start-up and close-down calibrations were conducted to assure operational parameters were met Audits
were conducted on August 31,1989 and October 20, 1989 with results showing less than a +/- 2 0%
deviation. All calibrations and audits were within allowable limits. On August 11, 1989, sampling was
initiated on a one sample every third day schedule. This schedule was chosen to allow for collection
of sufficient data to represent normal particulate concentrations. An every third day sampling schedule
has been shown to be adequate by EPA for this type of project (Fed Reg 1971)
Each air sampling filter used was stamped with both an EPA and APCD reference number. Filters were
hand delivered or mailed to the site operator when needed. The sampling procedure involves placing
a filter on the sampler by the operator, and adjusting a sample timer. Samplers were then activated by
the operator for a short period of time to allow for an "initial" air flow reading to be taken. The timer
then automatically started the sampler to provide a 24 hour (midnight to midnight) sample on the proper
day. Sampler operational data, as well as information about the sampling conditions (weather, etc),
was recorded by the operator on a "data slip". When the sampling period was completed, the operator
returned to the site and turned the sampler on for a brief period to record the "final flow" reading. The
"dirty" filter was then removed and folded in a specific manner that prevented loss of particulate maner
A clean filter was then placed on the sampler and an initial flow reading was taken for the next
sampling period. The exposed filter and data slip were placed into a manila folder and envelope for
transport back to the laboratory. Official discontinuation of monitoring occurred on November 13, 1989
In the laboratory, filters and data slips were removed and allowed to equilibrate for twenty four hours
to constant humidity and temperature. The filters were then subjected to a procedure that analytical^
7-5

-------
measured metals concentrations. The analytical method used was Ion Coupled Plasma Spectrophotometer
(1CP) The results expressed as micrograms of metal per filter were recorded and all of the information
returned to the Air Pollution Control Division for final calculations. By dividing the total filter metals
concentration by the total air flow, micrograms of metal per cubic meter of air sampled was determined.
Final results were entered onto a spreadsheet for reporting and modeling availability. Tables 7-1 to 7-4
contains the metals concentrations determined from the TSP and PM10 samplers. Table 1 contains the
metals data from the TSP filters. Many of the samples had metals concentrations at or below the
minimum detection limit of the analytical method. These are recorded as ND in Tables 7-1 and 7-3
By using the air volume, the lab calibration slope and intercept values in Tables 7-1 and 7-3, the
micrograms per cubic meter of air sampled can be calculated. These values are displayed in Tables 7-2
and 7-4
For statistical purposes a value of one half the Minimum Detectable Level (MDL) of the analytical
method is substituted for all "ND" observations. Detection values are found in Table 7-5. This is a
standard procedure for dealing with air quality data. Thus, in Tables 7-2 and 7-4 MDL values are
substituted for "ND" although no metals were detected. This produces a minimal, positive bias in the
data.
73 AIR MODELING METHODOLOGY AND RESULTS
Ambient air sampling was performed in Central City from August 11, 1989 until November 13, 1989.
Total Suspended Paniculate (TSP) and ten micron particulate (PM10) samples were collected and
analyzed to provide concentrations of the metals arsenic, beryllium, cadmium, chromium, copper, lead,
nickel and zinc. From this limited data set (4 months of data), a technique was used to estimate yearly
concentrations of these metals. Yearly concentrations can then be used to compute the risk from
exposure to these metals. The following describes the technique whereby the monthly metals data
measured at Central City.were converted to annual average concentrations.
Except for lead, these other metals are not routinely collected in the State's monitoring network. Since
1981, lead has been collected at four sites similar in topography and commercial activities as Central
City (at Leadville, Aspen, Steamboat Springs and Tellunde). There has been fourteen site years of
annual lead data collected at these four sites. The technique employed to determine estimated annual
average and maximum concentration of all metals in Central City basically compares the four months
7-6

-------
lead data from Central City to the annual average and parallel four months data collected at the other
four sites. The other metals measured at Central City are assumed to vary in a similar manner as lead
since the source of contamination is common to all the metals. Also the meteorology that produces
elevated lead values should produce high readings for the other metals. Direct correlation between the
observations is presented in Figures 7-1 through 7-7. The correlation between lead and arsenic, and lead
and zinc are both reasonably high (r: = .78 for As; r2 = .50 for Zn). For beryllium, cadmium,
chromium, copper and nickel correlation are all low. This is primarily due to the fact that most of the
the metals were near or below the minimum detectable limit of the analytical methodology. Thus the
lack of strong correlations is a product of the low ambient concentrations and not necessarily their
relationship to lead levels.
Monthly average lead concentrations for Leadville (1984, 1987, 1988), Aspen (1981, 1983, 1984, 1985,
1986), Steamboat Springs (1981, 1983, 1984, 1985) and Telluride (1981, 1986) are given in Figures 7-8
to 7-21. Some monthly data was unavailable during specific years. These values are represented as ND
in the figures. Ten of the fourteen site years data show the bimodal characteristic of lead concentrations
during the first of each year (January, February, March and April) and the latter part of each year
(August, September, October, November, and December). Table 7-6 shows the monthly average lead
concentrations measured at Central City for August, September, October and November of 1989. The
majority of the fourteen site years of lead data obtained from Leadville, Aspen, Steamboat Springs and
Telluride have higher lead concentrations than what was measured at Central City. This does not affect
the analysis since it is the seasonal and annual pattern of concentrations that is used to generate the
projected Central City data.
Based on the similar seasonal patterns observed at the comparison sites, it is reasonable to assume that
Central City would have a bimodal distribution of lead and other metals concentrations if measurements
were made year round. Table 7-7 shows the average monthly metal concentrations for all metals
measured at Central City in 1989.
The annual metals concentrations for Central City were calculated using the ratio of the four month
average lead concentrations to the twelve month average lead concentrations at the four site locations
(Leadville, Aspen, Steamboat Springs and Telluride) where complete years of data are available. The
numeric ratio obtained was applied to the four month average metals concentrations measured in Central
7-7

-------
Table 7-5
Comparison of Average Meials Concentration
For Two Detection Limit Scenarios


Overall


Overall



Averages


Averages


TSP
TSP

PM-IO
PM-10


Using 1/2
Using 0

Using 1/2
Using 0


LDL for HD
for ND
Difference
LDL tor ND
for ND
Difference
Metal
(ug/m3>
(yg/m?)
(ug/mi)
(ug/m3J
tug/m3)
(ug/m3)
Arsenic
0 0014
0 0014
0.0000
0 0008
0 0007
0 0001
Beryllium
0 0006
0 0005
00001
0 0007
00006
0 0001
Cadmium
00015
00015
0 0000
0 0006
0 0006
0 0000
Chromium
0 0085
0 0085
0 0000
0 0037
0 0037
0 0001
Copper
0.1520
0.1520
0 0000
0 0469
0 0469
0 0000
Lead
0.0334
0 0333
0 0000
0 0238
0 0238
0 0000
Nickel
0.0093
0.0084
0 0009
0 0103
0 0093
00010
Zinc
0.1051
0.1051
0 0000
0 0510
0 0510
0 0000

-------
City resulting in an estimate of the annual average metals concentrations. This technique was used in
order to estimate and compensate for seasonal variations in metals concentrations.
Table 7-8 shows the ratio of four months average lead concentrations to the annual lead concentration
for the fourteen site years of lead data. The four month average lead concentrations were compiled by
using all daily measured data from August, September, October and November for the fourteen site
years. The average ratio over the fourteen site years given m Table 7-8 is 0 958. The high and low
ratio from Table 7-8 are 1.667 and 479 respectively The fourteen site years of data, in Table 7-8, were
taken ftom data obtained for August, September, October and November at the four companion sites
At least three of the four Fall months were necessary to compute a valid seasonal average. This
seasonal value was then used with the annual average to calculate the ratios given in Table 7-8.
Table 7-9 gives the average concentrations for all metals measured at Central City from August 1989 to
November 1989.
Table 7-10 has been derived by using the high, low and average (over 14 site years) ratios in Table 7-8
and the monthly averages in Table 7-9 to estimate the high, low and average annual metal concentrations
at Central City for all metals measured in 1989. This is accomplished by dividing the measured Central
City average concentration by the appropriate ratio (high, low and average).
The annual average and high annual concentrations in Table 7-10 can then be used to compute the risk
from exposure to arsenic, beryllium, cadmium, chromium, copper, lead, nickel and zinc in Central City
Several meteorological factors need to be discussed which could impact the estimated annual metal
concentrations at Central City. These factors include precipitation and wind conditions at Central City.
The lack of precipitation could produce dusty conditions resulting in higher atmospheric concentrations
of the metals. Table 7-1*1 provides the annual average precipitation at all sites used in this analysis from
1981-1989. The 1989 data shows much less precipitation than over the preceding several years.
A special study was made to directly compare precipitation in Central City during the sampling period
with a 20 year record of regional averages. The Colorado Climate Center provided monthly averages
of precipitation based on a group of stations in the area around Central City. The town of Central City
is located near these stations (i.e., Nederland, Mt. Evans, Allenspark, & Gross Reservoir) and the
7-8

-------
Table 7-7
Average Monthly TSP and PMIO Metal Concentrations Measured At
Central City in 1989
(micrograms per cubic meter)
METAL
Part.
Size
Aug
Sept
Oct
Nov
Arsenic (As)
TSP
0008
0013
.0019
.0013

PM10
0005
.0067
.0010
0011
Beryllium (Be)
TSP
.0003
0006
0007
.0006

PM10
0004
0007
0008
0008
Cadmium (Cd)
TSP
.0001
0018
0018
.0017

PM10
0001
0003
0005
0026
Chromium (Cr)
TSP
.0110
0061
.0104
.0054

PM10
0014
0035
0049
0040
Copper (Cu)
TSP
.1427
.1546
.1596
.1310

PMIO
0466
.0472
.0507
.0328
Lead (Pb)
TSP
0169
0239
.0508
.0283

PMIO
0154
0217
.0258
.0376
Nickel (Ni)
TSP
0099
.0080
.0099
0106

PMIO
.0083
0091
.0125
0098
Zinc (Zn)
TSP
0831
.0821
.1439
.0764

PMIO
0528
0497
.0569
.0311

-------
that would not have been experienced in the four comparison communities. Thus, dispersion conditions
resulting in the highest Central City readings should have been frequently experienced in the comparison
fourteen sites' data.
In conclusion, the preceding analysis provides a viable technique to compute annual metal concentrations
from only four months of data collected in Central City. It is recommended that the "high" annual
concentrations, in Table 7-10, be used for each metal as a representative concentration in the risk
assessment. This is based on the concept that it is better to do the long-term risk evaluation on a
conservative estimate because of the short-term nature of the data base. The main strength of the
preceding analysis is that actual measured metal concentrations at Central City were used for this study.
Nonetheless, year round metal data from Central City for multiple years would have been preferable
in performing the risk assessment. Several meteorological variables (windspeed and precipitation) were
investigated to assess their impact on metal concentrations at Central City. Year round, multiple year,
windspeed and precipitation information at Central City would have been desirable to further analyze
their contribution to metal concentrations. Lastly, based on the meteorological data it is evident that a
site located to the east of the parking lot may be more representative of maximum concentrations.
7-11

-------
reference doses for some contaminants (cadmium, copper, silver, and zinc); thus, it was concluded that
there was a potential for chronic health risks via this pathway. Direct contact with mine discharge water
from the Big Five mine and the Argo tunnel was estimated to potentially result in eye irritation, but not
dermal irritation.
Contaminant concentrations in groundwater in the Clear Creek and North Clear Creek sub-basins were
compared to available ARARs. The ARARs were exceeded in both sub-basins for cadmium, chromium,
copper, lead, manganese, and zinc. Arsenic cancer risks via groundwater consumption were 1x10' and
7x10', for the Clear Creek and North Clear Creek sub-basins, respectively.
Risks asst. -iated with inhalation exposures were evaluated for residents living near the Gregory and Argo
tailings piles For both sites, the estimated exposures from wind-blown dust were less than the health
criteria for non-carcinogenic effects. Average and maximum cancer risks for the Gregory tailings were
7x10"® and 3xl03, respectively For the Argo tailings, average and maximum cancer risks were 2xl05
and 3xlO"5, respectively. Cancer risks (to residents) associated with dust generated by dirt bikes at the
Gregory tailings were 5x10"® and 1 x 10"* for the average and maximum cases, respectively. Estimated
exposures for this pathway were less than health criteria.
Potential risks also were evaluated for incidental ingestion of tailings at the Gregory and Argo tailings
piles. At the Gregory tailings, the cancer risks associated with arsenic were lxlO5 and 5x10"* for the
average and maximum cases, respectively. Cancer risks for the Argo tailings were 8x10'* and 1x103 for
the average and maximum cases, respectively. At the Argo tailings, lead exposures, under maximum
exposure conditions exceeded the health criterion.
9.2.2 POTENTIAL RISKS TO AQUATIC ORGANISMS
Risks to aquatic organisms were evaluated for the following chemicals: aluminum, arsenic, cadmium,
chromium, copper, fluoride, lead, manganese, nickel, silver, zinc, and low pH. Concentrations of these
chemicals in Clear Creek, North Clear Creek, and in the wetland below National Tunnel were compared
to Federal ambient water quality criteria (AWQCs) or to the lowest-observed-effect level (LOEL)
Criteria for aluminum, cadmium, copper, lead, manganese, silver, and zinc were exceeded in Clear Creek
and North Clear Creek. In North Clear Creek, criteria for pH also were exceeded. In the wetland,
criteria were exceeded for aluminum, cadmium, copper, manganese, silver, zinc and pH. Toxicity values
9-3

-------
for trout identified in the literature were compared to the AWQCs, and it was concluded that aluminum,
copper, lead, and nickel may cause adverse effects at concentrations below the AWQCs.
93 IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN
Surface water, sediment, groundwater, tailings/waste rock, air, and fish were sampled as pan of the
Phase II RI. The extent of contamination in each of these media has been discussed and evaluated in
previous sections of this report, and therefore will be discussed only briefly in this section, focusing on
contaminant distribution relevant to the evaluation of potential exposures and risks to humans and aquatic
life. This assessment will evaluate those chemicals selected for evaluation in the Phase I risk assessment
These are. aluminum, arsenic, cadmium, chromium, copper, fluoride, lead, manganese, nickel, silver,
and zinc. pH also was selected for evaluation in the Phase I risk assessment and similarly will be
evaluated in this assessment. In addition, iron is selected for evaluation because it has been detected in
surface water at levels potentially toxic to aquatic life. Similarly, mercury (in fish) and beryllium (in air)
are selected for evaluation because of their potential toxicity to humans. Analytes not evaluated in this
risk assessment are chloride, nitrate, sulfate, calcium, magnesium, molybdenum, potassium, and sodium.
Chemicals evaluated in this assessment are termed chemicals of potential concern. Each of the chemicals
evaluated are known to be associated with mining wastes and were determined to be site-related in the
Phase I risk assessment. Therefore, they are assumed to be site-related in this risk assessment.
Sampling data are discussed below by medium for each study area (e.g., stream segment) to be evaluated
in the risk assessment. Study'areas are defined using the stream segment designations presented in
Section 6.0 (Habitat Evaluation). Data are summarized by presenting the frequency of detection and the
range of detected concentrations (standard units for pH). The frequency of detection provides an
indication of how common a chemical is within a given segment and whether the detection of a given
chemical was an unusual event. For all water samples, only total metal concentrations are presented (see
Sections 4.4.2 and 9 5.5 for discussions of total versus dissolved concentrations). All pH values are field
measured pH values.
9-4

-------
Inhalation of Dust. Residents are assumed to be exposed to chemicals in dust daily and to inhale
30 m3 of air/day. This inhalation rate is a suggested upper-bound value provided by EPA (1989a)
Residents are assumed to be exposed for 30 years and weigh 70 kg (EPA 1989a).
The values to be substituted into equations 3 and 5 are as follows:
CR = 30 m3/day
EF = 365 days/year
ED = 30 years
BW = 70 kg
AT = 30 years x 365 days/year for noncarcinogens
70 years x 365 days/year for carcinogens
Because the inhalation slope factor for arsenic is based on an absorbed dose, the target concentration for
arsenic also included an assumption of 30% absorption in the lung, based on EPA (1984).
9 4.3 RISK ASSESSMENT
In this section, risks are evaluated for human populations potentially exposed to chemicals of potential
concern at the site Pathway-specific comparisons to target concentrations are presented in Section
9 4 3.1. Potential effects associated with lead exposure are evaluated separately in Section 9.4 3.2.
9 4 3.1 Comparison to Target Concentrations
Risks are evaluated by comparing the measured concentration of a chemical in an environmental medium
with target concentrations for each pathway associated with that medium. Measured concentrations that
exceed target concentrations are assumed to pose a potential threat to human health via exposure by that
pathway. (For potential carcinogens, if the measured concentration equals the target concentration, then
the excess lifetime cancer risk is 1x10"*. Likewise, if the measured concentration is 10 times the target
concentration, then the excess lifetime cancer risk is 10 times as great [i.e., lxlO"5]. If the measured
concentration is 10 times less than the target level then the cancer risk level is 1x10'.) In addition, even
if no chemical exceeds its individual target concentration, adverse health effects are considered possible
if the sum of the ratios of measured concentration to target concentrations for all chemicals with a given
toxic endpoint (e.g., cancer, dental fluorosis, gastrointestinal distress) exceeds 1. Toxic endpoints for
9-25

-------
the chemicals of potential concern are presented in Table 9-25. This approach is used in this assessment
to evaluate additive effects from multiple chemical exposures. For noncarcinogenic chemicals, this
approach is equivalent to the derivation of a hazard index under a forward risk assessment approach. For
carcinogenic chemical, this approach is equivalent to summing risk estimates for individual chemicals.
Additive risks will be of concern in those situations where the measured concentrations are less than the
target concentration but are greater than or equal to 1/n of the target concentration, where n is the total
of number of chemicals being evaluated for a given endpoint for a given pathway
Comparisons to target concentrations are discussed below by pathway. For all pathways, target
concentrations in a given medium are compared to the maximum (measured or estimated) concentration
of the chemical in that medium. Maximum concentrations were used in the comparisons instead of other
concentration estimates (e g , arithmetic mean) to simplify the data processing portion of the risk
assessment; the budget provided to conduct the risk assessment was not large enough to support extensive
data processing as well as quantitative assessments of both human health and environmental risks'. Use
of the maximum concentration is a conservative risk assessment approach EPA (1989a) recommends
that chemical exposure point concentrations evaluated in Superfund risk assessments be the upper 95
percent confidence limit on the arithmetic mean concentration. If the calculated upper confidence limit
exceeds the maximum detected value at the site, EPA recommends that the maximum detected
concentration be evaluated in the risk assessment. Typically, for small sets of environmental monitoring
data, such as those for the various study areas of Clear Creek site (e g., three surface water samples from
CC1, seven from CC2), the upper confidence limit on the arithmetic mean exceeds the maximum detected
value. Therefore, use of the maximum concentration in this risk assessment is most likely consistent with
EPA guidance.
Ingestion of Surface Water While Swimming. Table 9-26 compares the maximum detected
surface water concentrations in Clear Creek (CC1 - CC4), South Fork, West Fork (Wn. WF2), North
Fork (NF1), Chicago Creek (CHC1), and Fall River (FR1) with target concentrations developed for
swimming exposures. All chemical concentrations are between one and six orders-of-magnitude below
their target concentration. Thus, exposure to chemicals while swimming in the area's creeks does not
appear to pose a potential threat to human health under the assumed exposure conditions.
4 Target concentrations for air also were compared to average concentrations because these
were calculated by the CDH/APCD.
9-26

-------
"iS.i 9-25
y "3X.C
.3-: '¦ocer :
:jnce-
:a-:e"
Carce"
»" tarter
uaonium
C-.-ct jit (V !
Cesser
r"jc- .ce
"aiasa-ese
N - «eigr.t
Skin and mucous memprane
argyria
Anemia and reduced siccd
caocer
!a) E'dpemt jpon »hicn tre ;;nic >ty cr-ter-on is sasea
(:) "oxiCity criterion Sasec on a -.o-observed-acverse effect ^eve1
Tcxic endDO.nts ."eoctea .n tie iterature are listed n ;arentheses
NA = Net appucaoie Cancer slope factor not developed for this cnemical

-------
Children swimming in these waters are unlikely to experience dermal irritation from water contact; the
minimum pH of the creek waters for which swimming exposures were evaluated generally was in the
range of 6.3 to 7.5. The minimum pH in the main stem of North Fork was 4.35, measured during low-
flow conditions, however, could cause some dermal irritation. In addition to swimmers, visitors that
dabble their hands in ponded water or mine discharge while touring the mines in the area could be
exposed to low-pH waters and experience skin irritation. For example, the minimum pH of
approximately 2.0 in the Argo Tunnel and the Quartz Hill Tunnel could cause corrosive skin irritation
burns.
Ingestion of Fish Table 9-27 compares cadmium and mercury concentrations in fish collected
from Clear Creek (CC1 - CC4) with target tissue concentrations developed for fish ingestion Again,
measured concentrations are well below (approximately an order-of-magnitude) target concentrations
Therefore, ingestion of Clear Creek fish containing cadmium and mercury, does not appear to pose a
threat to human health In addition, as indicated in Section 9.3 6, mercury concentrations are well below
the FDA action level of 1 0 mg/kg Exposures to lead in fish could not be evaluated here because
toxicity criteria are not available and the Integrated Uptake/Biokinetic Model used to assess lead
exposures in this report (see Section 9.4 3.2) is not applicable to adults In addition to possible risks
from lead exposures, persons ingesting fish from Clear Creek could be at an increased health risk if any
of the other chemicals of concern are accumulating to toxic levels in fish. With the exception of zinc,
however, none of the chemicals of potential concern accumulate in fish to the degree of cadmium or
mercury. Accumulation of zinc in fish is unlikely to pose a human health threat because of zinc's
relatively low toxicity to humans.
Ingestion of Drinking Water. Tables 9-28, 9-29, and 9-30 compare target concentrations for
drinking water with the maximum concentrations reported forprivate wells, monitoring wells, and surface
water intakes for municipal supplies, respectively.
As indicated in Table 9-28, several private wells have maximum concentrations that exceed target
drinking water concentrations, and therefore, ingestion of water from these wells could be associated with
adverse health effects. In wells DW-05, DW-06, DW-09, and DW-12, the arsenic concentration exceeds
the target concentration for carcinogenic effects by factors of 65, 182 , 40, and 30, respectively. This
corresponds to excess cancer risks of 7xlO"J, 2xl0"\ 4xl0"5, and 3xl0"5. In well DW-07, the
concentrations of cadmium and manganese exceed their respective target drinking water concentrations
No other chemicals were detected at a concentration that exceeds the individual target drinking water
9-27

-------
"ABLE 3-26
::uD4n s:n :f ; :-<-5aseo sjrface 'jate^ -ascet 33ncent3a~ 3n$ *: «ix-u'.-
-.."AC- JA7-3 IC'fCiN^AT-CNS NCE3T'3N C: j.S-ACE -A'£i -J-'i_£ UM'NG
'Corcent-at ens -scarted .- -5/')
Cusrr. a
3 s<. ¦:
Zc-:e~t-j:
asea
B:-s 'i]

CC2
C23
CCA
Scuth "cr<
C iear Creek «:i
«r 2
N"!

::
A-se1- z
.-
.30
-' - \
NO
'.0
NO
NO
NO NO
NO
3

• j
~

-2 1 = )
5 CO
1
NO
0 9
1 2
0 5 3 7
3 2
.3

* v
2-.rem Lfn
45
;co
NO
NO
NO
NO
•NO NO
"0
= 3
N ^

" « r «»g ^
373
:co
20
42
3 2
5
4 7
NO
2C3

•,**
r .cr re
c:-.
:co
5C0
630
900
400
300 4 3C0
530
0" 0
" *

^a-ga^ese
- •"
:co

355
1 340
.8
22 10.300
. i 4
« £sO

"
n c < e 1
'.it
33C
-2
50
NO
30
NO NO
NO
57
'13

I "c
. 333
300
364
750
215
408
81 398
27
z zzz

. ¦*
(2) ixcec:
'. = ! *=srge:
as -c:ec i
:cr-:e.-:-3:
1 :ar;e: c:
rs ce- vec
-ce'-t-a:
sasec cn
ens
:ar:
ser'ved
•-c;en i:
sased cr
effects
r-oncarc icgen'c effsc:s




Not ZSZSCZSZ

-------
TABLE 3-28
COMPARISON OF R.'SK-BASED GROUNDWATER TARGET CONCENTRATES *0
G#OUNOWATER CONCENTRATIONS !N DOMESTIC WE'.LS INGEST.GN
(Ccncent'ations reported in ug/')
Risk-Based	C iear C-een
Target		-	
Chemical Concentrations (a) DV-04	OW-05 OW-06 Ou-08 CW-C9 :w-i: :w-.2
Arsenic
35
0 041 (b)
NO
2 7
7 5
NO
i 3
NO
. 6
Cadmium
IB
NO
NO
NO
ND
NO
NA
s:
Cctcer
I 400
5 6
NO
ND
NO
NO
5 5
7
r 'Lor-ce
2 :oo
600
SOO
1,800
700
1.800
700
i ico
u2-gaiese
7.000
NO
3 5
293
ltB
27
2
' ; "
N <:
-------
'A:l: r-£7
::u°4R'::n :f : :<-a;s£3 r:.-	*«:" :;scik>""iT'cs$
*c	ar• c.s	:f -"s-1
,C:icer:-a:'ens recctec - ~g'
-------
cchpar-son :f rs<-2AS-: crc'.ncua-es tapce: cc.ncentpa-'cns *d «ax-hum
cscuncwate* ;:,,,ce\"at'c,;s n «cn ng »Ell; crincng «a*e^ nce-"!cn
;-at ;-s -ecc'ted '-g/'!

R s<-iasea


"cr:» F;-<

"a-;et
Clear C-eek
¦test C ear
C ear C-eeK
;-e* :a•
C:-:e-:-a:.sn (3;
3-a -age
Creek Cra'-age
]r3 nage
Ai'lvijm




Arsen'c
55
ND
NO
3 5

0 :¦>: (a)



Cadmijm
13
312
NO
•12
C."r;m-uni
10
NO
ND
9
Cesser
i JCG
6 790
NO
630
- 'jjride
2 :?o
2 900
500
2 IOO
"anga-ese
7 jCC
50 CC0
.2
27 300
N c
-------
23-Apr-30 MUNICPAL
TABLE 5-30
CC^ARISON OF RISIC-9ASE0 SURFACE VATE3 TA°Glt C:nCEN"a"CNS "C max.Uijm ='jqc4CL 'JA'ER CONC£N"^a" "'(<
AT "UN 1C: PAL DRINK NC WAT En D * V i RS' ON ?G NT; NCET'ON " D= NK !.G .A'S*
[Zonce'".'at ens -eiortec
Chemica 1
5' s*-Bssed
Target
:;nce"t-3:,sn (a)
Idaho Springs
31ac< Hawk
Oecrjetcwn
Eto re
Caomium
18
NO
0 5
0 5
NO
Cesser
1.J00
3
12
J
NO
f ibO"de
2.100
300
NO
300
NO
Pa-gar,ese
7.000
11
135
22
7
. 'i;
7.000
5
177
81
24
(a) Based on noncarclnogeme effects
NO = Not detected

-------
concentration, although some chemicals approached their target concentration. In addition, the sum of
the ratios of measured concentration to target concentration does not exceed one for any group of
chemicals with the same toxic endpoint.
As Table 9-29 shows, several chemicals were detected in monitoring wells at maximum concentrations
above their target drinking water concentration and therefore, ingestion of groundwater from these areas
could be associated with adverse health effects, (n the Clear Creek area alluvial groundwater, the
maximum detected concentrations of cadmium, copper, fluoride, manganese and zinc exceed the target
concentrations, and that of nickel is essentially equal to the target concentration. In Clear Creek area
bedrock groundwater, the maximum detected concentration of fluoride exceeds its target concentration.
In North Fork area alluvial and bedrock groundwater, the maximum detected concentrations of arsenic
(for carcinogenic effects only), cadmium, manganese, and zinc exceed target concentrations. The arsenic
concentrations correspond to excess cancer risks of 9x103 (alluvium) and 7xl0'5 (bedrock) The
concentration of fluoride in North Fork area alluvium equals its target concentration. No chemicals were
detected in West Fork area groundwater at concentrations above target concentrations. As Table 9-30
shows, the maximum chemical concentrations in surface water at municipal drinking water diversion
points are well (between one and three orders-of-magnitude) below target drinking water concentrations
Ingestion of Tailings. Table 9-31 compares chemical concentrations in tailings with target
concentrations developed for exposures of children playing on tailings piles. Except for arsenic, the
maximum concentration of all chemicals is between one and three orders-of-magnitude below the target
concentration. The maximum concentration of arsenic in all tailings piles, except the Empire tailings,
exceeds target concentrations for carcinogenic effects by factors ranging from slightly greater than 1 up
to 57 This corresponds to excess cancer risks ranging from lxltt6 to 6xl0"5. Thus, children playing
on tailings piles under the assumed exposure conditions may be at an increased of contracting cancer over
a lifetime.
If tailings were used in some manner in residential areas in the future, residents also could be at an
increased risk of contracting cancer over a lifetime. The risks for residents could be approximately 10
times greater than that for children because residents could be exposed more frequently (i.e., daily versus
72 days/year for children playing) and for a greater number of years (e.g., 30 years versus 10 years for
children playing).
9-28

-------
Inhalation of Dust. Table 9-32 compares average and maximum estimated air concentrations to
target air concentrations developed for residential exposure to chemicals in dust. The average and
maximum concentrations of each chemical exceeds the target air concentrations by factors ranging from
slightly greater than 1 to SO for the average concentrations and from slightly greater than 1 to 100 for
maximum concentrations. The total excess cancer risk (for all chemicals) is approximately 6x10'' using
the average concentrations and 1x10"* using maximum concentrations. The greatest proportion of total
inhalation excess cancer risk is attributable to chromium concentrations. Thus, residents in the Central
City area may be at an increased risk of contracting cancer over a lifetime for inhalation of dust The
exposure evaluated, however, is very conservative in that it assumes 24-hour/day exposure for 30 years.
While this is a plausible exposure scenario for a small segment of the population, it most likely is not
representative of exposure in the majority of the population.
Ingestion of non-respirable dust panicles is not expected to add significantly to dust exposure risks
because all chemicals for which inhalation exposures were evaluated are less toxic via the oral route. In
fact, cadmium, chromium, and nickel are not carcinogenic via the oral route. Arsenic and beryllium,
though carcinogens by the oral route, are less potent carcinogens; the oral potency factors for arsenic and
beryllium are 25 and 2 times smaller than their respective inhalation potency factors.
Children playing on tailings piles are likely to be exposed to higher chemical concentrations in air than
area residents, but because their duration of exposure is likely to be shorter than residents (eg., a few
hours versus 24 hours/day for residents and 72 days per year versus 365 days per year), inhalation risks
are probably no greater than those estimated for residential exposures. However, children playing on
tailings piles and engaging in activities that generate significant amounts of dust (e.g., dirt bike riding)
could be at increased excess cancer risk compared 'sidents. In the Phase I risk assessment, the
estimated excess lifetime cancer risks for dirt bike rio^ it the Gregory tailings pile were approximately
an order-of-magnitude greater than those for residents living near the Gregory tailings pile.
9 4 3 2 Estimates of Lead Exposures and Risks
As discussed earlier, EPA has not developed a RfD or cancer potency factor for lead and therefore, an
alternative approach is used in this assessment to evaluate lead exposures at the Clear Creek site. The
approach used is modeled after the approach used by EPA for setting ambient air standards for lead and
is based on a linear pharmacokinetic model of lead which takes into account lead uptake, retention, and
excretion. The model, termed the Integrated Uptake/Biokinetic Model, estimates blood lead levels in
exposed individuals.
9-29

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9.6.1 HUMAN HEALTH EVALUATION
Risks to human health are not expected from ingestion of surface water when used as drinking water,
ingestion of surface water while swimming, and ingestion of fish based on the exposure scenarios
evaluated in this assessment There are potential risks associated with ingestion of groundwater,
incidental ingestion of tailings, and inhalation of airborne dust. Arsenic contributes most significantly
to risks from groundwater and tailing All the chemicals evaluated for the inhalation pathway pose risks
to human health Lead exposures from ingestion of soil and dust and from ingestion of groundwater pose
potential risks to children.
9 6 2 ENVIRONMENTAL ASSESSMENT
Ri9l» to Ti'sm Trout could be acutely affected in all segments of the mainstem of Clear Creek,
particularly in CC2. South Fork Clear Creek does not pose acute risks to trout and there is a moderate
risk of acute effects in Trail Creek No acute effects are expected in Chicago Creek (CHC1) or Ute
Creek. Trout are not expected to be at risk of acute effects in FR2 and they are at low risk of acute
effects in FRI In NF1, Gregory Gulch and Chase Gulch, trout are at risk of acute effects. Risks of
acute effects are moderate in Four Mile Gulch and Russell Gulch. In WF1, trout are at risks of acute
effects, particularly from cadmium. Chemical concentrations in Lions Creek and Woods Creek also pose
a high risk of acute toxicity to trout. No acute effects are expected in Mad Creek or in WF2. All of the
tunnel discharges, except the mine discharge below SW-26, are expected to be highly acutely toxic to
fish.
Past storm event chemical concentrations in Soda Creek, NF1, and Gregory Gulch present a high risk
of acute effects to fish. Estimated risks could be less tf the chemical concentrations associated with
storms are quickly flushed from the system, thereby reducing the duration of exposure.
In the mainstem of Clear Creek (CC1-CC4), trout are at moderate to high risk of adverse chronic
(reproductive) effects. Trail Creek and Browns Creek also pose significant risks of chronic effects.
Risks of chronic effects are relatively low in Chicago Creek and Ute Creek, and are low to moderate
in Fall River. In North Fork Clear Creek there is a clear risk of adverse reproductive effects.
Tributaries to this stream also pose chronic risks, including Russell Gulch, Four Mile Gulch, Gregory
Gulch, and Chase Gulch. Potential risks of adverse reproductive effects are high in West Fork Clear
Creek ftom Woods Creek to the confluence of Clear Creek (WF1). Chemicals in Lions Creek and
9-77

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Clear Creek/Central City Site
Mining Waste NPL Site Summary Report
Reference 3
Excerpts From Remedial Investigation Report - Addendum Number 2
Argo Tunnel - DRAFT; Clear Creek/Central City, Colorado; EPA;
July 1988

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tfOlibli
ADMINISTRATIVE RECORD
SF FILE NUMBER
3,S
DRAFT
REMEDIAL INVESTIGATION REPORT
ADDENDUM NO. 2
ARGO TUNNEL
CLEAR CREEK/CENTRAL CITY, COLORADO
JULY. 1988

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OOll'ji :
File Name: 26RI1
Project No. 2687
1.0 INTRODUCTION AND SUMMARY
1.1 PURPOSE
In July, 1985, EPA initiated a Remedial Investigation/
Feasibility Study (RI/FS) for the clear Creek/Central City
CERCLA site (Figure 1-1). The site is located approximately 3 0
miles west of Denver, Colorado. Current studies include
investigations of acid nine drainage discharges and milling and
mine wastes from five mine tunnels in the Clear Creek and North
Clear Creek drainages. The Argo Tunnel, which is the subject of
this Remedial Investigation (RI), is one of these tunnels. The
Clear Creek/Central City site was nominated for listing on the
Superfund National Priorities List (NPL) in 1982 and added to
the NPL in 198 3.
ZPA is conducting the Clear Creek/Central City RI/FS to
determine the nature and extent of the threat presented by the
release of toxic substances, pollutants or contaminants; the
extent to whicn the release or potential for release may pose a
threat to human health and the environment; and the extent to
which sources can be adequately identified and characterized.
RI/FS efforts are intended to gather and evaluate sufficient
information to develop proposed remedial actions.
The goal of this RI was to obtain the additional data and
characterize the Argo Tunnel site in support of alternative
evaluations to eliminate or substantially lower the quantity of
contaminants discharging from the Argo Tunnel. Acid mine water
presently discharges from the tunnel at approximately 0.46 cubic
feet per second (cfs) or 206 gallons per minute (gpm). This
acid water contains elevated levels of heavy metals, and
discharges into Clear Creek. Additionally, large surges or
"blowouts" of acid mine drainage have been recorded.
This RI has been prepared in accordance with the provisions of
the Superfund Amendments and Reauthorization Act of 1986 (SARA),
the Comprehensive Environmental Response, Compensation and
Liability* Act (CERCLA) (42 U.S.C 960.1, et. seq.), and the
National Contingency Plan (NCP). The following U.S. EPA
documents have also been followed: Guidance on Feasibility
Studies Under CERCLA f EPA. 1985 and Guidance for Conducting
Remedial Investigations and Feasibility Studies Under CERCLA
fDraft. March 1988).

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00110,1 
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0 0 i i t) 17
o Tunnel geotechnical data. Most available data in the
literature focuses on mining, economic geology and tunnel
operations. However, supplemental information was obtained
during this investigation by rehabilitating the tunnel to
gain safe access to a distance of approximately 1,560 feet
from the portal. The investigation focused on collecting
geologic, hydrogeologic and rock mechanics information
required for determining the feasibility of bulkhead
placement and seepage control. The investigation was also
necessary to determine tunnel conditions in anticipation of
more extensive rehabilitation, evidence of causes for
blowouts, and to examine possible sources of water entry and
conditions of the acid mine water and sludge inside of the
tunnel.
o Blowout data. Historical information on blowouts was
obtained and evaluations were performed on cause, magnitude
and frequency of blowouts.
1.4 SUMMARY
HISTORICAL MINING DATA
The Argo Tunnel portal is in Idaho Springs, Colorado at an
elevation of 7,560 feet. The tunnel length is 4.16 miles,
ex-ending from the portal in a northward direction, through
several mineralized veins to beneath the headwaters of Gregory
Gulch, west of Central City. Except for the 1,560 feet
renabilitated for investigation, the tunnel is presently
inaccessable due to roof falls, impounded water and accumulated
sludge.
There are eight ma]or mining zones that connect to the Argo
Tunnel along its 4.16 mile length, via several laterals. There
are 91 surface openings and 21,400 feet of vein strike
(intersection of the veins with the surface) in this system.
The estimated total volume of void space or mined out stope in
the system is about 1,490,000 cubic yards.
1-3

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OOllb-<
BLOWOUT DATA
There are historical recordings of at least two "blowouts" from
the Argo Tunnel. The first documented blowout occurred in
January, 19-4 3, when mining activities in the Kansas lateral,
located about four miles into the tunnel, tapped a large
quantity of impounded water. Four miners were killed in the
accident. A second event, in Kay, 198 0, occurred from "natural"
causes, probably the collapse of one or more roof falls that
were damming water. The event forced the closure of water
intakes for six downstream users of Clear Creek water,
including the Coors Brewery and the City of Golden.
The probable cause of blowouts is the failure of roof-fall dams
in the tunnel or its connected laterals and mines. Observations
during the tunnel investigations support this conclusion.
Based on information obtained from the Argo Tunnel
investigations, a "worst case" blowout event was modeled on
CDM's Water Analysis Simulation Program. A high volume (3.1
million cubic feet) high intensity (990 cfs), short duration
(one hour) blowout was routed through Clear Creek, from Idaho
springs to Golden. The contaminant surge at Golden lasted for
almost two days, with contaminant concentrations peaking at
typically two orders of magnitude above background. For
example, zinc peaked after 3.5 hours at a concentration of
10,000 ug/L; the concentration then receded to a background of
44 0 ug/L after about 41 hours.

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00n$24
2.3 LATERALS AND WINE WORKINGS
A total of 36 laterals or drifts branch from the Argo Tunnel.
These are identified, along with their distances from the
portal, on Table 2-1. Only 10 of these laterals connect to mine
systems which, in turn, connect to the surface by shaft or
adit. These laterals are on the major veins intersected by the
Argo Tunnel (Figure 2-2).
Appendix A is an assembly of many of the mine and tunnel maps
and stope sections used to determine the tunnel-lateral-mine
interconnections, locate surface extensions (shafts, adits,
stopes) and elevations of the mines, and to estimate quantities
such as portal distance or volumes of stopes. There is an
estimated total of 91 surface openings and 21,400 feet of vein
strike associated with the Argo Tunnel system. A summary of the
pertinent surface features follows.
ARGO
TUNNEL
LATERAL
Gem
Sun and Moon
Saratoga
Hot Time
California,
Kansas-3urroughs
Prize
South Gunnell
NO.
SURFACE
OPENINGS
33
7
5
12
21
5
8
OF
OF VEIN
STRIKE fftl
5,600
1,300
1,900
2, 700
6,700
1,500
1,700
LENGTH LOWEST
COLLAR
ELEVATION fMSLl*
8131
9106
8790 (approx.)
9003
8995
8950 (approx.)
8800
TOTALS	91	21,400	8131 (Lowest)
* Elevation of the first direct opening, either shaft or adit,
to the surface above the level of the Argo Tunnel.
Elevation given in feet above Mean Sea Level.
Table 2-2 details the lateral mine-surface opening-elevation
summary and indicates conditions of the openings, where they are
Jcnown.
The detailed information represented by Table 2-2 and Appendix A
is necessary for determining the effects of locating water-tight
bulkheads at one or more locations in the Argo Tunnel. Figures
2-3 and 2-4 are representative schematics of the mine map stope
section information that demonstrate the various pathways and
possible discharge points that need to be considered for any
tunnel flooding scenerios. Figure 2-3 is for the Gem Lateral,
which has the lowest adits or shafts on the system, upstream of
the Argo Tunnel portal. Figure 2-4 is for the Kansas Lateral.
2-2

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Clear Creek/Central City Site
Mining Waste NPL Site Summary Report
Reference 4
Excerpts From Superfund Record of Decision: Central City/Clear Creek, Colorado;
James J. Scherer, EPA Region VIII, Regional Administrator;
March 31, 1988

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R«nw*al flMpent*
EPA/mxyRos-aaoig
MvchiStt
&EPA Superfund
Record of Decision:
Central City / Clear Creek, CO

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EPA/ROD/R08-88/019
Clear Creek/Central City, CO
Second Remedial Action
16. ABSTRACT (continued)
The selected remedial action for this site includes: slope stabilization at the Big
Five Tunnel and Gregory Incline; monitoring of the gabion wall at the Gregory Incline;
and run-on control at the Argo Tunnel, Big Five Tunnel, Gregory Incline, National
Tunnel, and the Quartz Hill Tunnel. The estimated present worth cost for this remedial
action is $1,049,600.

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SUMMARY
FOR THE
RECORD OF DECISION
SITE NAME AND LOCATION
Clear Creek/Central City Superfund Site
Clear Creek and Gilpin Counties, Colorado
Operable Unit No. Two
Tailings and Waste Rock Remediation
SITE DESCRIPTION
The Clear Creek/Central City Superfund site is located
approximately 30 miles west of Denver, Colorado, and primarily
consists of acid mine drainages and milling and mining wastes
from five mines/tunnels in the Clear Creek and North Clear Creek
drainages. The site encompasses the northeastern portion of
Clear Creek County and southeastern portion of Gilpin County.
Specifically, the focus of the Remedial Investigation was
five abandoned mines/tunnels proximal to the cities of Idaho
Springs, Black Hawk, and Central City (Figure 1). The tunnels
are the Argo Tunnel and Big Five Tunnel in the Clear Creek
drainage and the National Tunnel, Gregory Incline, and the Quartz
Hill Tunnel in the North Clear Creek drainage. The Argo portal
is within the city limits of Idaho Springs. The Big Five portal
borders the Idaho Springs city limits. The Gregory Incline is
within the Black Hawk city limits. The National Tunnel is within
a mile of the City of Black Hawk. The Quartz Hill Tunnel is
within a mile of the City of Central City.
The waste rock/tailings piles considered in this Operable
Unit were selected based on their location close to the acid mine
discharges. Currently, the major impacts on the water quality of
Clear Creek are the Big Five and Argo mine tunnel discharges.
The water quality of North Clear Creek is affected by the
National Tunnel discharge and seepage from the Gregory Incline
and the Quartz Hill Tunnel. The discharges from the five sites
were addressed in Operable Unit No. One.
In addition to direct discharge from the mine tunnels,
contaminated water may enter the creeks during overland sheet
flow. Overland runoff occurs during rapid snow melt and
thunderstorms. The resulting surface flow across the tailings
and waste rock piles dissolves soluble minerals and transports
particulate tailings and waste rock material into the creeks.
These mechanisms result in elevated creek acidity and metal
loads. The introduction of tailings and waste rock into the

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creeks could also occur due to catastrophic collapse of tailings
and waste rock piles during a flash flood or as a result of
undercutting of the base of the pile under any flow regime.
SITE HISTORY
The Clear Creek/Central City hard rock mining district is
historically one of the most mined areas in Colorado. At one
time, gold mining accounted for 85 percent of the activity,
silver for 1$ percent and other minerals, (e.g., copper, lead,
and zinc) the remaining 5 percent. The area includes over 800
abandoned mine workings and tunnels. Recent data indicate that
up to twenty-five mines and six milling operations are currently
operating in Gilpin and Clear Creek counties. The intensity of
mining operations has varied in recent years, due largely to
fluctuating market prices for precious metals.
Mining activity in the Central City/Black Hawk area
commenced in 1859. Placer gold was found at the mouth of Chicago
Creek, near Idaho Springs, in January of 1859 and, in May of the
same year, the first lode discovery in the Rockies was made in
Gregory Gulch between Central City and Black Hawk. Initially,
mining was concentrated in the Gregory Gulch area, including the
Gregory Incline. Exploration via adits and shafts rapidly
expanded to the south and west of Central City. Excavation of
the Quartz Hill Tunnel was begun in i860, largely for the purpose
of transporting ore from the overlying surface Glory Hole Mine to
mills in Central City. The tunnel is over a mile long. National
Tunnel construction was initiated in 1905 and continued to 1937.
The tunnel is believed to be over 3,100 feet in length.
The Argo Tunnel was constructed from 1893 to 1904. The
tunnel was built for the dual purpose of mine drainage and ore
transport. The total tunnel length is 4.16 miles, extending from
the portal in Idaho Springs in a northward direction to beneath
the headwaters of Gregory Gulch, west of Central City.
In July, 1982, the Clear Creek/Central City site was ranked
as Site No. 174 on the Interim Priorities List of 400 sites. The
site was added to the final National Priorities List (NPL) in
September, 1983. EPA began the Remedial Investigation (RI) of
the site in July, 1985. The RI Report was issued in June, 1987
and reported results from the study period of July, 1985 through
December, 1986. An addendum to the RI was issued in January,
1988 to report results from additional studies conducted in April
and May, 1987.
A removal action was conducted by EPA's Emergency Response
Branch at the Gregory Incline in March, 1987 to protect human
health and the environment from hazards associated with the
collapse of a retaining crib wall. A collapse would have allowed
3

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the tailings to slide into North Clear Creek and EPA was
concerned that a large load of metals-laden tailings would wash
downstream into Clear Creek and contaminate the municipal water
supply of the City of Golden, Colorado. EPA removed an old
deteriorated crib retaining wall and decreased the slope of the
tailings pile to stabilize it. EPA then constructed a gabion-
basket retaining wall.
SCOPE AND ROLE OF THE OPERABLE UNIT
During the course of the RI, EPA determined, in accordance
with 40 CFR Section 300.68(c), that the Feasibility Study CFS)
should be divided into Operable Units in order to remediate site-
specific problems.
The Operable Units include:
Operable Unit No. One - Mine Tunnel Discharge Treatment
(Record of Decision signed in September, 1987)
Operable Unit No. Two - Tailings and Waste Rock Remediation
Operable Unit No. Three - Blowout/Discharge Control
In addition, the State of Colorado has submitted an
application to EPA for monies to fund an investigation to
identify other areas within the mining district which may be
significantly impacting North Clear Creek and Clear Creek. The
State will also investigate the quality of the groundwater in the
area. Depending upon the results of the State study, EPA may
consider additional operable units.
SITE CHARACTERISTICS
A public health evaluation was conducted to identify
compounds which could pose a significant threat to human health
and the environment. Based on sampling of environmental media
and consideration of toxicity, twelve contaminants of concern
were identified and potential exposure pathways were analyzed.
Impacts on human health and the environment were assessed for
exposures due to inhalation and ingestion of material from the
piles and due to runoff from the piles and catastrophic slope
failure of the piles into the streams.
As stated, twelve contaminants were identified during the
public health evaluation as contaminants of concern in the Clear
Creek/Central City study area. Contaminants of concern were
chosen separately for human receptors and aquatic organisms.
Arsenic, chromium (VI), and nickel are present in relatively high
concentrations in the tailings and waste rock and have been rated
by EPA as Group A human carcinogens by the inhalation pathway.
Cadmium is a Group B1 carcinogen by inhalation and is a potent
4

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kidney toxin when ingested. Lead and silver are toxic
noncarcinogens and are present in relatively high concentrations
in the tailings and waste rock.
Contaminants of concern for aquatic life were chosen based
on their concentration in water, published criteria values (e.g.,
Ambient Water Quality Criteria (AWQC)), and supplemental data for
chemicals that lacked criteria. Contaminants include aluminum,
arsenic, cadmium, chromium, copper, fluoride, lead, manganese,
nickel, silver, and zinc.
Exposure to metals in tailings or waste rock can potentially
occur through inhalation of dust by people at or near the sites.
Two mechanisms for dust generation were considered in the
evaluation: (1) dust resulting from wind entramment of tailings
or soil particles; and (2) dust generated from human activities
(in particular, riding of dirt bikes on the tailings piles). The
Gregory tailings pile is readily accessible and in some areas is
quite compacted or has a surface crust- Dirt-bike riding is
known to occur at the Gregory tailings pile. The Argo tailings
are also readily accessible and are less compacted and more
friable than the Gregory tailings. The Argo tailings are not
used extensively by dirt-bike riders due to their steepness.
Currently, however, waste rock at Argo is being removed for use
in constructing roads. This activity, which involves operation
of dump trucks and front-end loaders, increases dust emissions
from this area.
Ir> addition to inhalation, exposure to metals in soil or
tailings can also occur by incidental ingestion. Tourists
visiting the mines may contact the tailings, although the
potential for significant exposure is low. Older children living
in the area, particularly those from ages 6 to 16 who have less
parental supervision than younger children, may play or ride dirt
bikes at the tailings piles especially during the summer months
when school is out.
Future use of the sites may include residential development.
Under this scenario, potential exposure pathways would include
incidental ingestion of contaminated material by the residents
over their life time. This potential future use residential
exposure scenario was also evaluated.
In summary, the major potential impacts at the site due to
tailings and waste rock are:
o Degradation of surface water quality caused by runoff from
the piles;
5

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o Degradation of surface water quality caused by collapse of
the piles into the creeks; and,
o Human uptake of metals through inhalation or ingestion.
Exposure to humans
Under both current land use conditions and potential future
use scenarios, the principal potential pathways by which human
receptors could be exposed to site contaminants from the tailings
and waste rock piles is through inhalation or ingestion of
material from the piles. Impacts resulting from ingestion of
surface water were evaluated as part of Operable Unit No. One.
Exposure scenarios for average and maximum plausible cases
were developed for both the inhalation and ingestion potential
exposure pathways. Based on estimates of exposure and a
quantitative description of each contaminant's toxicity, human
health risks were then assessed. The major conclusions of this
assessment are presented in Table 1 and can be summarized as
follows:
o Inhalation of wind-entrained dust from the Gregory Tailings-
pile results inupperbound lifetime excess cancer risks of
7x10~ and 3x10 for the average and maximum plausible
cases, respectively, primarily from exposure to arsenic.
Inhalation of wind-entrained dust from the Argo Tailing pil^
results ip upperbound lifetime excess cancer risks of 2x10
and 3x10 , for the average and maximum plausible cases,
respectively. Generation of dust by dirt bikes ridden at
the Gregory Tailings piles results in upperbound risks of
5x10 and 1x10 , for the average and maximum plausible
cases, respectively. Risks from inhalation of dust from the
other tailings and waste rock piles are similar.
o Ingestion of arsenic-contaminated material from the tailings
and waste rock piles under current use, or the episodic
exposure scenario, poses an upperbound lifetime excess
cancer risk of 2x10"5 for the average case and 1x10~4 under
maximum plausible conditions.
o Ingestion of arsenic-contaminated material from the tailings
and waste rock piles under the potential future use
residential scenario poses an upperbound lifetime excess
cancer risk of 1x10"4 under average conditions and 9x10~4
under maximum plausible conditions.
The risks for individual sites are provided in Table 1 and a
more detailed discussion of these exposure pathways and the
resulting risks can be found in the Public Health Evaluation,
6

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contamination would reach Golden where a maximum concentration
730 ug/L of aluminum is predicted. The aluminum concentration
Golden under ambient conditions is 200 ug/L. A collapse of th
Big Five pile would result in a maximum dissolved concentratic
of 1,100 ug/L of zinc at the collapse point, an increase from
400 ug/L of zinc under ambient conditions. This translates ir
a maximum concentration of 960 ug/L of zinc at Golden after two
days which would gradually decrease to 400 ug/L after eight days.
The zinc concentration at Golden under ambient conditions is
about 300 ug/L. The modeling results indicate that maximum
concentrations of aluminum and zinc would exceed AWQC in all
stream segments down to Golden. At Golden, the AWQC would be
exceeded by a factor of 24 and 89, respectively for aluminum and
zinc. Based on the modeling of zinc and aluminum, it is
estimated that concentrations of selected parameters in Clear
Creek at Golden would also exceed maximum contaminant levels
(MCLs) established under the Safe Drinking Water Act. The
results of the model clearly indicate an adverse impact on Clear
Creek due to collapse of the waste rock piles at the Big Five
Tunnel.
Similar analyses of collapse of the Gregory Tailings into
North Clear Creek have been performed. Results from this effort
indicate that both AWQC and MCL values would be exceeded in Clear
Creek at Golden as a result of a collapse.
Impact Due to Runoff:
Irr addition to collapse of the tailings and waste rock
piles, materials will also enter the stream due to runoff from
the piles during snow melt and storm events. The results of the
analyses of samples taken on Clear Creek and North Clear Creek
during storm events indicate that the average total aluminum and
zinc concentrations exceeded AWQC values by factors of 69 and 15
times, respectively. The results indicate potential impact on
aquatic life due to runoff during storm events. Impacts on human
health due to runoff from the sites are minimal because the storm
events are of limited duration.
Summary of Exposures to Aquatic Life:
The major conclusions of the assessment of exposure to
aquatic life can be summarized as follows:
o Several of the chemicals of concern are at concentrations
that exceed the ambient water quality criteria for the
protection of freshwater aquatic life (AWQC). In
particular, concentrations of zinc, copper, and aluminum
consistently exceed the acute and chronic AWQC. In
addition, concentrations of manganese in the water exceed
the lowest observed effect level in rainbow trout. Because
aquatic organisms are exposed to a mixture and not
l 0

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Clear Creek/Central City Site
Mining Waste NPL Site Summary Report
Reference 5
Excerpts From Preliminary Assessment of the Environmental Effect of
Mine Drainage on the North Fork of Clear Creek,
Gilpin County, Colorado; Fred C. Hart Associates, Inc.;
July 30, 1982

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RED C. HART ASSOCIATES, INC. • consultants 0012 o 7.'J
MARKET CENTER • 1320 17th STREET. DENVER. COLORADO 80202	.	(303) 829-1818
July 30, 1982
ADMINISTRATIVE RECORD
SF FILE NUM8ER
	 /.+
Mr. Keith 0. Schwab
Deputy Project Officer
Environmental Protection Agency
1860 Lincoln Street
Oenver, Colorado 80295
Dear Keith,
Following is our preliminary assessment letter report concerning mine
drainage pollution in the North Fork of Clear Creek.
As Assistant FIT Leader, Ian Hart, discussed with you and John Warden on
June 30, 1982, the site inspection was delayed by two weeks. Subsequently, the
letter report due dates for both the Argo Tunnel (F8-8205-01) and the North Fork
of Clear Creek (F8-8205-02) had to be delayed by two weeks. Approval for this
extension was granted by John Warden on July 12, 1982.
I hope that this preliminary assessment report concerning the North Fork
of Clear Creek is satisfactory. Please feel free to call if you have any
questions.
Sincerely,
FRED C. HART ASSOCIATES, INC.
"T
Donna Toeroek
FIT Leader
Enclosure
DT/et

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0012574
PRELIMINARY ASSESSMENT OF THE ENVIRONMENTAL
EFFECT CF MIME DRAINAGE ON THE NORTH FORK OF
CLEAR CREEX, GILPIN COUNTY, COLORADO ADMINISTRATIVE RECORD
SF FILE NUMBER
INTRODUCTION						— _
The North Fork of Clear Creek originates in western Gilpin County, Colorado
and flows to the southeast for about 12 miles to its confluence with the main
stem of Clear Creek. The North Fork flows through the historic Black Hawk-
Central City mining district at approximately seven miles upstream from its con-
fluence with the Clear Creek main stem. The area around Black Hawk and Central
City, and the hills to the south and west, constitute the most concentrated area
of hard rock mining in the state (Colorado Mined Land Reclamation Division,
1982, p. 14-11). Today, most of the mines are abandoned.
Acid mine drainage, from mines in the surrounding hills, enters the North
Fork of Clear Creek either directly or through a series of small tributaries in
the area. Acid mine drainage water contains a variety of metals in solution
which are leached from the mineralized wall rock of the mine area. Consumption
by animals or humans of water contaminated by metals can produce symptoms of
chronic poisoning.
According to the 1981 Colorado Division of Mines list of active mines,
there are 14 active mining operations and two active milling operations in
Gilpin County.
Purpose of the Study
This study was assigned by the U.S. Environmental Protection Agency (EPA),
Region VIII Deputy Project Officer, Keith Schwab under Technical Direction Docu-
ment Number F8-8205-02. The assignment directed the Region VIII Field Investi-
gation Team (FIT) to "review background information and provide preliminary
assessment." As part of the study the FIT was directed to prepare a MITRE Model
ranking of the site, and perform a site inspection.
- 1 -

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0 012 o 7 S
Moran and Vlentz (1974) conducted a follow-up study in 1972-73. The results
confirmed the North Fork as being heavily impacted by acid mine drainage.
Wildeman, et. al. (1974) identified and analyzed the drainage from six in-
active mines in the Central City-Black Hawk mining district. These mines are
the Quartz Hill Tunnel, Gregory Incline, National Tunnel, Bonanza Mine, Williams
Tunnel and the Rara Avis Tunnel. A correlation between the quality of the
drainage and the position of the mine adit in the are body was noted. Except
for the Williams Tunnel, all drainages contained at least one toxic trace ele-
ment in excessive concentrations.
Climate
Rapid temperature changes, an abundance of sunlight, and dryness charac-
terize the local Mountain climate. The atmosphere is clear, and the humidity is
normally quite low. Annual precipitation in the Idaho Springs area nearby to
Black Hawk and Central City, averages about 18 inches per year with much of this
in the form of snow. Occasionally, periods of higti winds or local cloud bursts
strike. Frosts occur in late spring and early fall, and the cool nights limit
the amount of growth. Average frost penetration reaches a depth of 5 to 6 feet
(McCal1-El 1ingson and Merrill, Inc., 1981). The average yearly temperature at
Idaho Springs is 43.2 degrees F, with an average yearly high of 87 degrees F and
an average yearly low of -12 degrees F (McLaughlin Engineers, 1981, p. 111-5).
Geology
The Front Range is composed of Precambrian gneisses and schists that have
been intruded by granite (Tweto, 1968). The tertiary veins and small stacks in
the Precambrian schist and gneiss are the sources of ores in the Black Hawk and
Central City districts (Yanderwilt, 1947). Marsh and Queen (1974) have esti-
mated southern Gilpin County mineral production value through 1970 at 95 million
dollars, of which gold amounted to 85 percent, and silver about 10 percent, with
the remainder being due to copper, lead, zinc and uranium.
Unconsolidated alluvial material, consisting primarily of sand and gravel
with grain size ranging from silt to boulders, is situated in the valley bottoms
- 5 -

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0012 5 71)
and along larger water-courses. Groundwater is found in limited quantities
associated with this unconsolidated material. During periods of high flow, sur-
face water having high metal concentrations may exchange with alluvial ground
waters and thus degrade ground water quality. However, there is no information
available to quantify the extent to which this occurs.
RESULTS
Data
North Fork sample analysis results are best illustrated in Figures 1 and 2,
and Table 1, each from McLaughlin Engineers (1981, p. VI-17, 18, and 19).
The polluting elements of primary interest and occurrence in this study are
iron, manganese, zinc, cadmium, lead, and copper. Relative to toxic effects,
Klusman and Edwards (1976) state the following:
The elements of interest are either toxic at 1» concentrations in
water or else produce undesirable tastes or other aesthetic
problems when used as a domestic water supply. As a result, the
U.S. Public Health Service and the U.S. Environnental Protection
Agency have set standards for public water supplies. Very high
dosages of many heavy metals produce rapid and severe damage or
death to animals, commonly known as acute poisoning. At lesser
concentrations more subtle effects occur that result in gradual
development of symptoms of chronic poisoning. It is this case
where the hazards of elevated trace metals in water lie. The
animal or human shows little outward sign of problems to the
untrained observer and he is unaware of the situation until the
cumulative poison has done its damage. Unfortunately, in most
cases the impact is irreversible. Table 2 lists the trace elements
of interest in this study, their drinking water standards, and a
brief description of the health effect of high concentrations.
- 6 -

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0 0 i 2 5 S -j
Relationship to Groundwater
Groundwater aquifers capable of transporting the contaminated mine water
from surface drainage are the unconsolidated alluvium in the valley bottoms, and
fractures throughout the Precambrian age bedrock which make up the Rocky Moun-
tain Front Range. The fracture conduits are capable of carrying contaminated
water from virtually any of the local underground mines and mineralized areas,
or local drainages including the North Fork of Clear Creek. In this manner, the
contaminated water can intersect wells or other water sources at unpredictable
locations and depths. Klusman and Edwards (1976) refer to the evaluation of
water quality data throughout the Colorado mineral belt as "complex," due to the
rock fracture aquifer relationship to mineralization and mining.
Past studies have indicated several point sources of concern in the study
area around Black Hawk and Central City. Sampling by McLaughlin Engineers
(1981) and studies by the Colorado Mined Land Reclamation Division (1982) indi-
cate that the point sources most contributing to the degradation of the North
Fork of Clear Creek are the Quartz Hill Tunnel, National Tunnel, and the Gregory
Incline. Numerous other mine sites, mills, and nonpoint sources contribute acid
metal drainage to the North Fork of Clear Creek either directly or through vari-
ous drainages throughout the area; but, the three point sources cited are appar-
ently the most notable occurrences.
FIT research at the Gilpin County Courthouse revealed that the Quartz Hill
Tunnel is apparently currently owned by Central City because patent status was
never resolved on the property. McLaughlin Engineers (1981) state that drainage
from the Quartz Hill Tunnel joins Nevada Gulch and flows for about 200 feet
before joining a box culvert 2,000 feet long that travels under the Central City
parking lots and joins and Gregory Gulch under Central City itself. The gulch
comes above ground below Central City and continues to Black Hawk where it again
joins an underground box Culvert that travels 1,500 feet under Black Hawk to the
North Fork of Clear Creek.
The National Tunnel is apparently situated on the Wright Claim which is
owned by Harold Caldwell. Mr. Caldwell lists two addresses as follows:
- 11 -

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0 GI u 5 o
of not only the North Fork of Clear Creek, but the Clear Creek main stan from
the North Fork confluence downstream. Propped supports to the cribbing wall are
anchored directly in the North Fork Channel which is subject to shifting. Col-
lapse of the cribbing wall is obviously imminent.
FIT's original MITRE ranking gave the North Fork study area a score of just
over 23 on a scale with a maximum of 97.2. After the site inspection was com-
pleted and EPA's project officer had received additional information, EPA
revised the ranking. The revision included both the Argo tunnel (letter report,
TOO# F8-8205-01) and the North Fork of Clear Creek in one ranking. The result-
ing final score was 50.3. Combining both sites into one ranking should not be
construed as contributing to a higher score; rather, MITRE related factors at
both sites are nearly identical. If rated separately both sites would have
identical scores.
Apparently some of the revisions to the MITRE score occurred because Clear
Creek's North Fork and main stem can be considered critical habitat. In fact
the site inspection revealed several scattered wetland areas along the North
Fork of Clear Creek Canyon wherever the canyon bottom widens.
CONCLUSIONS
Data from McLaughlin Engineers (1981) clearly demonstrates that mine and
mineralized area drainage from throughout the Black Hawk-Central City mining
district is contributing significant metal pollutants to the North Fork of Clear
Creek. This conclusion is substantiated by previous studies cited earlier. The
most significant point source contributors to this pollution are three local
mines.
Quartz Hill Tunnel
National Tunnel
Gregory Incline
- 13 -

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Clear Creek/Central City Site
Mining Waste NPL Site Summary Report
Reference 6
Excerpts From Preliminary Assessment of the Environmental Effect
of Mine Drainage from the Argo Tunnel,
Clear Creek County, Colorado; Fred C. Hart Associates, Inc.;
July 22, 1982

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FRED C. HART ASSOCIATES. INC. • consultants
00125
MARKET CENTER . 1320 17th STHbfcT. DENVER. COLORADO 80202
(303) 629-1818
July 22, 1982
Keith 0. Schwab
Deputy Project Officer
ADMINISTRATIVE RECORD
SF FILE NUMBER
L±
Envirormental Protection Agency
1860 Lincoln Street
Denver, Colorado 80295
Dear Keith,
Following is our preliminary assessment letter report on the Argo	Tunnel
site at Idaho Springs. Because the site assessment was delayed by two	weeks,
the Assistant FIT Leader, Ian Hart had discussed with both you and John Wardel 1
in a meeting on June 30, 1982, to extend the due dates for both the Argo	Tunnel
(F8-8205-01) and North Clear Creek (F8 -82 0 5-02) assignments by two	weeks.
Approval for this extension was granted by John Wardell on July 12, 1982.
I hope that this preliminary assessment report for the Argo Tunnel is
satisfactory. Please feel free to call if you have any questions.
Sincerely yours,
FRED C. HART ASSOCIATES, INC.
Donna Toeroek
FIT Leader
DT/tlr

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001251)1
PRELIMINARY ASSESSMENT OF THE ENVIRONMENTAL EFFECT OF
NINE DRAINAGE FROM THE ARGO TUNNEL, CLEAR CREEX COUNTY, COLORADO
ADMINISTRATIVE RECORD
SF RLE NUMBER
INTRODUCTION 		
The Argo Tunnel, at Idaho Springs, is a major point source for acid mine
drainage water which flows directly into Clear Creek. Acid mine water contains
a variety of metals in solution, leached from the metals present in the wall
rock of the mine area. Consumption by animals or humans of water contaminated
by metals can produce symptoms of chronic poisoning.
Purpose of the Study
This study was assigned by the U.S. Environmental Protection Agency (EPA),
Region YIII Deputy Project Officer, Keith Schwab under Technical Direction
Document Number F8-8205-01. The assignment directed the Region VIII Field
Investigation Team (FIT) to "review background information and provide (a)
preliminary assessment." As part of the study the FIT was directed to prepare a
MITRE Model ranking of the site, and perform a site inspection.
The study was initiated to evaluate the potential for the Argo Tunnel site
to qualify for remedial funding under Superfund. The MITRE Model ranking
provides a base for comparing the hazard level of this site with other potential
Superfund sites across the nation.
Scope and Approach
In order to accomodate the EPA directive, the FIT coordinated each assigned
task with EPA's project officer Bill Rothenmeyer. Project tasks were divided
into five areas consisting of background, MITRE ranking, site inspection, data
assessment, and recommendations. Work in all of these areas was shared by both
the FIT and EPA's project officer.
- 1 -

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001i:oi)2
Considerable time and effort was spent by both EPA's project officer and
the FIT to gather and assess the background data available. Several studies on
the Argo drainage had been previously conducted.
The FIT submitted a MITRE ranking on schedule according to the original
Technical Direction Document. However, because of the volume of background data
available, the ranking was based upon incomplete background information. Subse-
quent data collection and policy decisions by Region VIII EPA enabled EPA's pro-
ject officer to update the ranking into final form.
Due to scheduling problems with local officials and the site owner, EPA's
project officer was not able to arrange the site inspection until June 30, thus
delaying all other aspects of the project proportionally. The delay, however,
allowed both the FIT and EPA's project officer additional time to gather and
assess background information.
BACKGROUND
History
The Argo site is currently owned by Jim Maxwell of Idaho Springs. Mr.
Maxwell currently utilizes the tailings near the tunnel portal as decorative
landscaping rock which he sells to local distributors. Although he would like
to process the material for its gold content, local public pressure opposed to
the presence of a cyanide leaching process in the area forced him to abandon the
plan. The site is also operated as a local tourist attraction with tours of the
old Argo mill site. The Argo Tunnel and Mill site is listed with the National
Register of Historic Places (Number 5CC76, January 31, 1978).
"Clear Creek has many uses below the Argo Tunnel Study Area. As Clear
Creek passes down Clear Creek Canyon towards Golden, it is widely used for
recreational purposes, such as kayaking, picnicing, etc. Between the mouth of
Clear Creek Canyon and its confluence with the South Platte River, Clear Creek
is heavily relied upon as a municipal and industrial water supply. At least 75
percent of the flow in the Clear Creek diversions is used for municipal and
industrial purposes, while the ranainder is used for golf course irrigation,
- 2 -

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On 4 ri r-- '\ •
On May 21, 1980, a large reservoir of water that had been impounded within
the Argo Tunnel broke loose and burst out of the tunnel by some type of interior
collapse (McLaughlin Engineers, 1981, p.YI-5). The resulting catastrophe
flooded the entire area around the adit and washed a large portion of the Argo
Mill tailing pile into Clear Creek. Water quality sampling on the following day
showed serious violations of metals standards (McLaughlin Engineers, 1981,
p.YI-5). Unusually heavy rains prior to the Argo catastrophe may have caused
the sudden mine water "blow-out".
As previously mentioned, the FIT and EPA's project officer discovered that
several studies have been previously conducted at the Argo Tunnel and Mill
site. Many of these studies included year-round sampling to assess water
quality both upstream and downstream from the Argo site. Most notable of these
previous studies are Moran and Wentz (1974), Boyles, et al. (1974), Klusman and
Edwards (1976), Wentz (1977), and McLaughlin Engineers (1981). Recent compila-
tions by the Colorado Mined Land Reclamation Division (1982) also illustrate the
mine drainage problem at the Argo site in studies related to Abandoned Mine
Lands Reclamation through the Federal Surface Mining Control and Reclamation Act
(SMCRA).
CIiroate
Rapid temperature changes, an abundance of sunlight, and dryness charac-
terize the Idaho Springs climate. The atmosphere is clear, and the humidity is
normally quite low. Annual precipitation in the Idaho Springs area averages
about 18 inches per year with much of this in the form of snow. Occasionally,
periods of high winds or local cloud bursts strike the area. Frosts occur in
late spring and early fall, and the cool nights limit the amount of growth.
Average frost penetration reaches a depth of 5 to 6 feet (After: McCall,
Ellingson, and Merrill, Inc., 1981). The average yearly temperature is 43.2
degrees F, with an average yearly high of 87 degrees F and an average yearly low
of -12 degrees F (McLaughlin Engineers, 1981, p.III-2).
- 4 -

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Clear Creek/Central City Site
Mining Waste NPL Site Summary Report
Reference 7
Excerpts From Site Inspection Report;
William Rothenmeyer, EPA Principal Inspector;
June 30, 1982

-------
OOiSodo
Q rpA rvTENTIAL HAZARDOUS WASTE SITE
WCm SITE INSPECTION REPORT
REGION
SITE NUMBER flo 6a M.ijn-
• a 6r M4J
GENERAL INSTRUCTIONS: Complete Sections I and QI through XV of this form as completely is possible. Then use the informs*
Uon oo this f°™ to develop a Tentarve Disposition (Section II). File this form in its entirety In the regional Hazardous Waste Log
File. Be sure to include all appropriate Supplements! Reports ui the file. Submit a copy oI the forms to- U.S. Environments! Pro-
tection Agency; Site Tracking System. Hazardous Waste Enforcement Tack Force (EN-33S), 401 M St., SW; Washington, DC 20440.
[. SITE IDENTIFICATION
A SITE NAME
Afiso TWJB-
8. STREET (or ochtr td*ntttltr)
ToA+tO SPRIH&S
D. STATE E. ZIP CODE
Co
F COUNtY NAME
ci£&l cek&i
C. SITE OPERATOR IN FORMATION
1 NAME
;jiw mAscw£U_
3 STREET 4 CJTY
2 TELEPHONI
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2.0SO
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h. SEALTY OWNER INFORMATION (tt dilloront from optrmtor at »n»)
1 NAME
S CITY
2 TELETHON!
A STATE
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3 ZIP CODE
I SITE DESCRIPTION
TlMOAjec ACIT / VffalLLs TAIL1U C
j. type of ownership
| 1 1. FEDERAL ~ 2- STATE ~ 3. COUNTY ~ 4 MUNICIPAL 23 5* PR'VATE
II. TENTATIVE DISPOSITION (complete ttus section last)
A. ESTIMATE GATE OF TENTATIVE
OPPOSITION fato., d«y, S yr.)
3. APPARENT SERIOUSNESS OF PROBLEM
( | 1 HIGH ~ 2- MEDIUM ^ 3* L0W CD *• NONE
\ PREPARER INFORMATION
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III. INSPECTION INFORMATION
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C SITE REPRESENTATIVES INTERVIEWED (corporate oilieimtM, workwrt, toiidw)
1 N AMC
2 TITLE 4 reuSPHONC NO.
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ADMINISTRATIVE RECORD
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EPA Fwb T30J0-3 (10*7')	PAGE 1 OP 10	Conf.nm Ob

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0012367
	Vm. HAZARD DESCRIPTION (continued)
,^f)
~7[ G. CONTAMINATION OP SURFACE WATER
cl£*^
CP1 Ban. T7070.1 /10.741
PAGE 5 OP IO
Continue On Reverse

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U U i Z o 6 'i
on?	_ 					
	.-a. HAZARD DESCRIPTION (continued)		
£ TO FLORA/FAUNA
F,SMKILL cl£a* cf^Et	TWt <^<30 IUom&L	£o^Dft?0
O.iAjA^	i)V£ IU£ CDhJVAft IiJATlfy^
fiK *\i/Jl»6 A^Ti\;|t^
I	| J CONTAMINATION OF AIR
|	| K NOTICEABLE ODORS
I I L CONTAMINATION OF SOIL
2 M- PROPERTY DAMAGE	__.
fldob/o; from. BLcu/ cvr £ovjld	^ Hgusihz u*\iu_
EPA Form T2070-3 (10-79)
PAGE 6 OF 10
Continue On Page 7

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Mining Waste NPL Site Summary Report
Cleveland Mill
Silver City, New Mexico
U.S. Environmental Protection Agency
Office of Solid Waste
June 21, 1991
FINAL DRAFT
Prepared by:
Science Applications International Corporation
Environmental and Health Sciences Group
7600-A Leesburg Pike
Falls Church, Virginia 22043

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DISCLAIMER AND ACKNOWLEDGEMENTS
The mention of company or product names is not to be considered an
endorsement by the U.S. Government or by the U.S. Environmental
Protection Agency (EPA). This document was prepared by Science
Applications International Corporation (SAIC) in partial fulfillment of
EPA Contract Number 68-WQ-0025, Work Assignment Number 20.
A previous draft of this report was reviewed by Anne Schober of EPA
Region VI [(214) 655-6710], the Remedial Project Manager for the
site, whose comments have been incorporated into the report.

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Mining Waste NPL Site Summary Report
CLEVELAND MILL
SILVER CITY, NEW MEXICO
INTRODUCTION
This Site Summary Report for Cleveland Mill is one of a series of reports on mining sites on the
National Priorities List (NPL). The reports have been prepared to support EPA's mining program
activities In general, these reports summarize types of environmental damages and associated mining
waste management practices at sites on (or proposed for) the NPL as of February 11, 1991 (56
Federal Register 5598). This summary report is based on information obtained from EPA files and
reports and on a review of the summary by the EPA Region VI Remedial Project Manager for the
site, Anne Schober.
SITE OVERVIEW
The Cleveland Mill site is an abandoned lead, zinc, and copper mill. The site covers 5 to 10 acres
and is located about 5 miles northeast of Silver City, New Mexico. The land is owned by Mining
Remedial Recovery Company (MRRC), formally Bay and Company. Cleveland Mill was proposed as
an NPL site in June 1988 and added to the NPL in a final rulemaking dated March 31, 1989.
The site contains two steeply sloped piles of mine tailings (a total of approximately 12,000 cubic
yards) heavily contaminated with lead, zinc, copper, and arsenic. The piles, which are uncovered,
unstabilized, and unlined, are located 100 yards south of the Continental Divide at the headwaters of
Little Walnut Creek. Pooled runoff has been observed in drainage leading through and away from
the tailings. Tailings solids have been observed in the streambed as far as 2 miles below the site
indicating that the tailings are eroding directly into Little Walnut Creek. There are also two ponds
onsite. The site is unfenced and two Forest Service roads converge onsite. The principal constituents
of concern are lead, silver, zinc, copper, and arsenic.
Residential areas are located downstream of the site. The nearest residence is 0.9 mile south of the
site. Although there are less than five residences within a 1-mile radius of the site, residential density
increases greatly south of the site and closer to Silver City. Within 3 miles of the site there are 337
private wells used for drinking water, crop irrigation, and livestock watering. There are no public
water supply wells within a 3-mile radius of the site. Additionally, livestock raised south of the site
may be watered with surface water from Little Walnut Creek. There are no commercial, industrial,
I

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Cleveland Mill
or large-scale agricultural activities within a 3-mile radius of the site. Little Walnut Creek and
downstream waters are used for recreational activities such as swimming and fishing (see Figure 1).
To date, a Preliminary Health Assessment has been conducted for the Cleveland Mill site by the
Agency for Toxic Substances and Disease Registry. The State, the contractor for the Remedial
Investigation/Feasibility Study, was selected in early 1991 and field work is expected to begin in the
spring of 1991.
OPERATING HISTORY
Cleveland Mill was a crushing and gravity separation operation that was abandoned in the 1920's.
Although the mill is no longer standing, the foundation of the pumphouse is still in place at the north
end of the dam (Reference 1, page 10). During operation, tailings from the mill were transported via
a slurry pipeline and deposited on the sloping side of a small valley, creating the tailings piles. The
piles are similar in shape, structure, and composition, and they are uncovered. One pile contains
3,070 cubic yards of tailings and the other pile contains 9,299 cubic yards of tailings (Reference 1,
page 13). No containment system or diversion system is in use, according to the Documentation
Records for the Hazard Ranking System. The reservoir, northwest of the tailings piles, provided the
industrial water supply during the operation of the mine (Reference 1, page 10; Reference 2, page 6).
SITE CHARACTERIZATION
The Preliminary Health Assessment (May 9, 1990), indicated that the possible exposure pathways
include ground water, surface water, soil, air, and the food chain. The contaminants of concern have
been identified as lead, silver, zinc, copper, and arsenic (Reference 1, page 1; Reference 2, page 1;
Reference 3, Cover Sheet).
Preliminary site characterization was done through EPA's Environmental Monitoring Systems
Laboratory in Las Vegas (EMSL-LV) utilizing X-ray Fluorescence technology. A field (portable) X-
ray Fluorescence instrument was used to analyze 148 samples for lead, copper, zinc, and arsenic.
The survey was conducted in July 1990. The results of this effort are contained in a Site Screening
Report (SSR) and will be used to streamline the Remedial Investigation/Feasibility Study report.
2

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Mining Waste NPL Site Summary Report
mm.
m
1*0$r

COS
t»*r
m/o%
\
B
&
a
FIGURE 1. CLEVELAND MILL AREA, SILVER CITY, NEW MEXICO
3

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Cleveland Mill
Ground Water
The aquifer in the site vicinity consists of coarse alluvium overlying fractured bedrock (Colorado
Formation, which is intruded by dikes). The Health Assessment indicated that the water table within
the floodplain of Little Walnut and Silva Creeks (a clean downstream watercourse to which Little
Walnut Creek is tributary) may be as near to the ground surface as 14 feet. The ground water flows
to the southwest near the facility and flows toward the south closer to Silver City (Reference 2,
page 5).
Four private wells, located along the valley of Little Walnut Creek downstream of the Cleveland Mill
site, were sampled during the Site Investigation Follow-up (on March 30, 1987) to document releases
to the ground water. These wells were along the probable path of contaminant travel. A well owned
by the U.S. Forest Service and located along Picnic Creek (an unaffected drainage tributary to Little
Walnut Creek) was sampled to provide background concentrations (Reference 1, page 9).
Zinc was detected in several downgradient wells. The greatest zinc concentration in the downgradient
wells was 1.70 parts per million (ppm) in the Carson well (see Figure 2-Locations of Ground Water,
Surface Water, and Soil Sampling Points) (Reference 1, page 4) as compared to a zinc concentration
of 0.65 ppm in the background, upgradient well, indicating that the ground water is contaminated
with zinc (Reference 1, page 9). The Site Investigation Follow-up Report noted that although the
Cleveland Mill site is a possible source of the high concentrations of zinc in the ground water, the
steel casing and galvanized pipe used to construct the private wells in the area is also possible source
(Reference 1, page 10).
No copper, lead, silver, or arsenic was detected in any of the wells sampled. The pH, measured
during the same sampling period, was 6.52 in the well located closest to the site and only 25 meters
from Little Walnut Creek. Background pH was measured at 7.43. The pH levels of 2 to 3 in the
mine-tailings runoff is the cause of the low pH level in the well (Reference 1, page 9).
The Preliminary Health Assessment concluded that continued leaching and migration of tailings
contaminants may eventually affect the ground-water quality of private wells within the site area.
Although elevated levels of zinc were detected, the levels detected are still below EPA's Secondary
Maximum Contaminant Level (SMCL) for drinking water of 5,000 parts per billion (ppb) (Reference
2, page 7).
4

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Mining Waste NPL Site Summary Report
NCWMOUCO
/ \ \l(£rou«
-------
Cleveland Mill
Surface Water
The headwaters of Little Walnut Creek originate near the site. The Creek flows through Silver City
and past a school and municipal park, and it is used for recreational activities. Approximately 200
feet northwest of the mine-tailings piles, there is a pond on the north side of a small dam. The pond
was used as an industrial water supply during mine operation. In addition, approximately 1,000 feet
northeast of the site there is a small, spring-fed pond. Neither surface-water nor sediment samples
were taken from these ponds.
Data collected during the Site Investigation Follow-up indicate that contaminants from the mine
tailings have impacted Little Walnut Creek. Because the alluvial deposits beneath Little Walnut Creek
and Silva Creek are recharged directly by surface-water flows from the Cleveland Mill tailings,
ground water may be affected. Contamination originating onsite extends downstream in surface
waters and stream sediments at least S.9 stream miles below the facility (Reference 1, page 8).
Water samples taken from Little Walnut Creek during the Site Investigation Follow-up revealed
maximum copper and zinc concentrations up to 200 and 2,000 times, respectively, above background
concentrations in the uncontaminated portions of Picnic and Silva Creeks (Reference 1, page 2;
Reference 3, Surface Water Route Section, Observed Release). The maximum copper concentration
was 11 milligrams per liter (mg/1), and the maximum zinc level was 110 mg/1. The maximum lead
concentration in the samples was 0.04 mg/1; this is more than four times background values. Arsenic
values were not found to be significandy above background levels. Additionally, Little Walnut
Creek, at the drainage site, had a pH of 3.35. Background pH was between 7.40 and 8.14
(Reference 1, page 2). The surface-water sampling results are provided Table 1 (Reference 1, page
2).
TABLE 1. SURFACE-WATER SAMPLING RESULTS (mg/1)
Location
pH
Zn
Cu
Pb
As
Picnic Cr. (Bkgd)
7.4
<0.05
<0.05
<0.01
<0.005
Little Walnut Cr. ab. Picnic Cr.
3.35
110
11
0.01
0.008
Little Walnut Cr. bl. Picnic Cr.
6.42
24
2.4
<0.01
<0.005
Little Walnut Cr. 0.49 mi. S. of
confluence with Picnic Cr.
7.42
18
2.2
<0.01
<0.005
Little Walnut Cr. 1.09 mi. S. of
confluence with Picnic Cr.
8.05
18
2.4
<0.01
<0.005
Little Walnut Cr. ab. Silva Cr.
8.22
6.2
0.88
0.04
<0.005
Silva Cr. (bkgd)
8.14
<0.05
<0.05
<0.01
<0.005
Silva Cr. bl. Little Walnut Cr.
8.14
2.6 j
0.40
<0.01
<0.005
6

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Mining Waste NPL Site Summary Report
Surface water within the site vicinity is riot used as drinking water, but it is used for cartle watering.
Human contact with surface water may occur because Little Walnut Creek and the pond located near
the site are used for recreational activities (Reference 2, page 7). Sediment samples taken in 1986
showed maximum concentrations as indicated in Table 2.
TABLE 2. SEDIMENT SAMPLING RESULTS
Contaminant
Background Concentration
(Picnic Creek)
Maximum
Concentration
(in ppb)
Arsenic
3,100
17,000
Copper
43,000
1,160,000
Lead
16,000
93,000
Silver
800
13,000
Zinc
140,000
5,660,000
These data show that metal concentrations in streambed sediments are significantly greater than
background. The maximum concentrations for zinc, copper, and arsenic are 40, 30, and 5 times the
background levels, respectively (Reference 1, page 5).
Soils
Mine tailings were dumped directly onto local soils at the Cleveland Mill site. Soil contaminants are
expected to be transported offisite by water and wind erosion due to the steep slopes of the tailings
piles and the small particle size of the mine tailings. Elevated levels of metals were found in onsite
and offsite soils during the Site Investigation Follow-up. Surface soil maximum concentrations
included those listed in Table 3 (Reference 2, page 3):
TABLE 3. SOIL SAMPLING RESULTS
Contaminant
Maximum Concentration
(in ppb)
Arsenic
66,000
Copper
1,360,000
Lead
1,070,000
Silver
99,000
Zinc
7,690,000
7

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Cleveland Mill
The Site Investigation Follow-up Report (March 1987) determined that metals concentrations of all
contaminants of concern decreased with increasing distance from the mill site. As expected, the
greatest concentrations of all five metals were in the mine tailings themselves (Reference 1, page 6).
Because access to the Cleveland Mill site is unrestricted, trespassers may come in contact with soils
and mine tailings with high levels of metals by dermal contact with the soil, or ingestion or inhalation
of dusts. However, the Preliminary Health Assessment concludes that, although soils contain elevated
levels of metals, the site is remote and activity at the site is expected to be minimal (Reference 2,
page 7).
Air
Although air monitoring was not conducted during the preliminary site investigations, the finely
crushed rock which comprises mine tailings may be a source of fugitive dust during windy weather.
Winds may transport mine tailings into areas south and downgradient of the site, including residential
and cattle-grazing areas. This mine tailings dust may decrease air quality and impact nearby
residences. Recreational and remediation activities onsite could lead to an increase in suspended dusts
(Reference 2, pages 6 through 8).
Food Chain
Contaminant levels in the surface-water and sediment samples collected from Little Walnut Creek
during the Site Investigation Follow-up were sufficiently high to cause concern that site contaminants
may be bioaccumulated by edible fish. Livestock and game are unlikely to come directly in contact
with the mine tailings because of their location on steep slopes and because the piles are not
vegetated. Additionally, because no edible plants were observed at the site, contaminated plants are
not expected to adversely affect the food chain (Reference 2, page 6).
ENVIRONMENTAL DAMAGES AND RISKS
The Preliminary Health Assessment concluded that the Cleveland Mill site "poses a potential health
concern" (Reference 2, page 1). Because there is no control to site access, direct contact with the
contaminated mine tailings is possible (Reference 1, Cover Sheet; Reference 3, Cover Sheet). The
contaminants of probable public health concern at the Cleveland Mill site are arsenic, cadmium, lead,
and zinc (Reference 2, page 9).
8

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Mining Waste NPL Site Summary Report
Human exposure to arsenic may occur through ingestion, inhalation, and dermal absorption (the last is
the least likely exposure route). Ingestion may cause irritation of the digestive tract leading to
abdominal pain, nausea, vomiting, and diarrhea. It may also lead to an increased risk of liver,
bladder, kidney, and lung cancer. Additionally, ingestion of inorganic arsenic (the form most likely
found at the site) also causes a pattern of skin abnormalities. EPA estimates that a dose of 1
microgram per kilogram Gig/kg) per day of arsenic corresponds to a cancer risk of 1.5 X lffJ
(Reference 2, page 9). Inhalation of arsenic may cause similar health effects as ingestion. Arsenic
concentrations of about 200 micrograms per cubic meter (yg/m3) have been associated with irritation
of the nose, throat, and exposed skin. Dermal exposure to arsenic-containing compounds may lead to
irritation of the skin, eyes, or throat (Reference 2, page 9).
Humans may be exposed to cadmium at the Cleveland Mill site through ingestion or inhalation Only
1 - 5 percent of ingested cadmium is absorbed into the blood where 30 - 50 percent of inhaled
cadmium is absorbed. Once absorbed, cadmium is retained. Ingestion of cadmium may cause
damage to the kidneys and lead to hypertension. Long-term inhalation exposures at levels of 100
jig/m5 may increase the risk of chronic obstructive pulmonary disease and kidney toxicity, and
lifelong exposure of air containing 1 jtg/m5 may be associated with a risk of lung cancer of about 2 in
1,000 (Reference 2, page 9).
Human exposure to lead may occur through ingestion and inhalation at the Cleveland Mill site. Low
levels of lead exposure (both ingestion and inhalation) may cause decreased growth and decreased IQ
scores in children, and hypertension in middle-aged men. Pregnant women exposed to lead may
transfer it to the fetus and this may cause preterm birth, reduced birth weight, and decreased IQ. The
Centers for Disease Control (CDC) has cautioned that concentrations of lead in ingested soil or
inhaled dust greater than 500 to 1,000 ppm could lead to elevated blood lead levels in children. Lead
levels in excess of these values were found in onsite mine tailings and in the components of the road
surface immediately surrounding the site. Although short-term exposure may occur, the remote
location of the site should reduce the risk of long-term exposure to lead (Reference 2, page 10).
Human exposure to zinc may occur through ingestion and inhalation at the Cleveland Mill site. The
National Academy of Sciences has estimated the Recommended Dietary Allowance (RDA) for zinc is
15 milligrams (mg) a day. Long-term exposure to excessive levels of zinc (2.1 mg/kg a day) could
cause a copper deficiency. The human body eliminates zinc through excretion and sweat (Reference
2, page 10).
9

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Cleveland Mill
REMEDIAL ACTIONS AND COSTS
The Remedial Investigation/Feasibility Study field work is expected to begin in the spring of 1991.
To date, no remedial action has been taken, and costs for remediation have not been determined.
CURRENT STATUS
The New Mexico Environmental Improvement Division (NMEID) is taking the lead on the Remedial
Investigation/Feasibility Study, planned to begin in the fall of 1990, for the Cleveland Mill site. In
March 1990, the Environmental Improvement Section received a forward planning grant from EPA.
A cooperative agreement between EPA and NMEID is in place. NMEID has selected a contractor to
perform the Remedial Investigation/Feasibility Study and is currently in contract negotiations. Field
work is expected to begin in the summer of 1991 (Reference 4).
10

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Mining Waste NPL Site Summary Report
REFERENCES
1.	Site Inspection Follow-up Report; Cleveland Mill, Silver City, New Mexico; EPA; March 30,
1987.
2.	Preliminary Health Assessment, Cleveland Mill Site, Silver City, New Mexico; Agency for Toxic
Substances and Disease Registry, U.S. Public Health Service; May 9, 1990.
3.	Hazard Ranking System Score Sheet and Documentation for Cleveland Mill Site, Silver City,
New Mexico; Richard A. Rawlings; March 31, 1987.
4.	Telephone Communication Concerning Cleveland Mill; From Mary Wolfe, SAIC, to Anne
Schober, EPA; August 13, 1990.
11

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Cleveland Mill
BIBLIOGRAPHY
EPA. Site Inspection Follow-up Report, Cleveland Mill, Silver City, New Mexico. March 30, 1987.
New Mexico Environmental Improvement Division. Site Inspection Follow-up Report, Cleveland
Mill, Silver City, New Mexico. April 11, 1986.
Rawlings, Richard A. Hazard Ranking System Score Sheet and Documentation for the Cleveland
Mill Site, Silver City, New Mexico. March 31, 1987.
Stevens, Mary (SAIC). Mining Information Collection Sheet for Cleveland Mill, Silver City, New
Mexico. June 12, 1990.
U.S. Public Health Service, Agency for Toxic Substances and Disease Registry. Preliminary Health
Assessment, Cleveland Mill, Silver City, New Mexico. May 9, 1990.
Wolfe, Mary (SAIC). Telephone Communication Concerning Cleveland Mill to Anne Schober, EPA.
August 13, 1990.
12

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Cleveland Mill
Mining Waste NPL Site Summary Report
Reference 1
Excerpts From the Site Inspection Follow-up Report;
Cleveland Mill, Silver City, New Mexico; EPA; March 30, 1987

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SITE INSPECTION FOLLOW- UP REPORT
Cleveland Mill
March 30,1987.

-------
CLEVELAND MILL
Si 1 ver City, New Mexico
Cleveland Mill is an abandoned lead, zinc, and copper mill witn ove^
12,UOO cudu yards of contaminated tailings available for migration to
air, surface #ater, arc groundwater routes. The site covers approximately
a to Id acres and is located about 5 miles northeast of the town of Stiver
City, New Mexico.
Tne uilinys piles, heavily contaminated with lead, zinc, copper, aru
arsenic, are located approximately 100 yards south of the Continental
Divide at tne neadwaters of Little Walnut Creek. Contamination, as evidence1
oy low pH and heavy metals, has been detected at least 5 miles downstream
or tne site which is attributable to the mill tailings. Little Walnut
Creek and downstream waters are used for recreation and fisning.
Contamination of local groundwater 1s considered likely, with the
taiimys piles and contaminated streams as areas of recharge to the
alluvial aquifer, which is in hydrologlc connection with deeper bedrock
aquifers. Over 100U people depend on private wells for drinking water
witrtln three miles of tne site.
Direct contact wltn contaminated tailings piles are also likely, as
tnere is no control over site access. The site is unfenced, and two
Forest Service roads converge onslte.

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RESULTS
Data regarding wells in the vicinity of the site are presented in Appendix I
Field notes from the site visit made by PA/SI staff for this SIF are given in Appendix n
Raw data from sampling conducted during these visits are given in Appendix til
SURFACE WATER ROUTE
Goals of surface water route investigations were to confirm a surface water
use and to extend the site boundary as far as possible, both downstream toward
Silver City and upstream toward the swimming reservoir.
Site Boundary
to extend the site boundary downstream, samples of water and sediment
were collected at several locations alona three drainage courses: little Walnut
Creek, which drams the tailings, Picnic Creek, which is an unaffected drainage
tributary to Little Walnut Creek; and Silva Creek, a clean downstream watercourse
to which Little Walnut Creek is tributary (see Figures 1 and 2).
Results of surface water sampling and analysis for four metals and pH are
displayed in the table below
SURFACE WATER SAMPLING RESULTS (mg/l)
location
Picnic Cr (bkgd)
Little Walnut Cr ab Picnic Cr.
Little Walnut Cr. bl. Picnic Cr.
Little Walnut Cr. 0.49 mi. S
of confluence with Picnic Cr.
Little Walnut Cr. 1.09 mi. S
of confluence with Picnic Cr.
Little Walnut Cr. ab. Silva Cr.
Silva Cr. (bkgd)
Silva Cr. bl. Little Walnut Cr.
These data demonstrate that natural background concentrations of metals, as
represented by Picnic Creek and Silva Creek samples, are consistently below
detection limits. Metals concentrations in the affected drainage, in contrast, are
significantly greater than background. The maximum observed concentration of
zinc is 110 mg/l, more then 2000 times background. The maximum observed copper
concentration of 11 rrg/1 is more than 200 times background. The maximum lead
value was 0.04 mg/l. more than four times background. A small amount of arsenic
was also detectea in one sample, but this concentration cannot be shown to be
significantly above background. Background pH is 7.4 • 8.14. However, drainage
from the site into Little Walnut Creek had a pH of 3.35 it the time of sampling.
Within a short distance of mixing with the waters of Picnic Creek, pH
conditions in Little Walnut Creek return to background values. Concentrations of
zinc and copper, however, remain elevated significantly above background even
after mixing with the waters of Silva Creek, several miles farther downstream. The
data presented above document extension of the site boundary downstream at
least as far as Silva Creek.
OH
Zn
Cu
Pb
As
73

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r,
&

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J^L
Figure l: Locations of Ground Wacer, Surface
Water and Soil Sampling Points.
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-------
Cu
Pb
AO
As
AT
ir
31
5~1
19
S
o.s
12
630
93
13
17
1160
22
0.8
9.0
1070
28
0.8
10
710
22
0.9
86
22
16
08
3 3
S3
13
0.4
3.0
130
23
0.8
58
Results of surface water stream bed sediment sampling are displayed .n the
following table:
SURFACE WATER SEDIMENT SAMPLING RESULTS (ug/g)
location	Zn
Picnic Cr (bkgd)	U(T*
Ltl. Walnut Cf. ab PfcmcCr. 130
Ltl WaJnutCr. bl PtcmcCr. 1190
Ltl. Walnut Cr. 0.49 m> S 4750
ofconfi with Picnic Cr.
ltl. Walnut Cr. 1 09 mi. S 5660
of confl. with PtcmcCr.
Ltl. Walnut Cr ab.SilvaCr. 5080
Silva Cr. (bkgd}	80
Silva Cr. bl. Ltl. Walnut Cr. 410
StlvaCr. 0.7 mi. Sof	1100
confl. with Ltl. Walnut Cr.
These data demonstrate that natural background concentrations of metals in
sediment, as represented by samples from Picnic Creek and Silva Creek, are
consistent and low. Metals concentrations in stream bed sediments of the affected
drainage, in contrast, are significantly greater than background. The maximum
observed concentration of ztnc is 5660 ug/g, more than 40 times background. The
maximum observed copper concentration of 1160 ug/g ii about 30 times
background. The maximum arsenic concentration of 17 ug/g it more than 5 times . -
background. Concentrations of lead, and silver were significantly above
background in one sample.
Note the different patterns in downstream concentrations of metals in
sediment versus metals in water. The most contaminated water sample was
collected from Little Walnut Creek above its confluence with Picnic Creek and the
degree of contamination in the water itsetf declined regularly with increasing
distance downstream and with the addition of clean water from tributaries. In
comparison, the sediment samples describe a different pattern. The sediment
sample corresponding to the most contaminated water sample is virtually clean and
not different from background. At the next downstream sampling station, lead,
arsenic and silver reach tneir highest concentrations in sediment. Copper and zinc
also appear there, but they continue a gradual rise in concentration and then
gradual decline. Copper and zinc are higher in sediments 1 mile downstream from
the junction of Picnic Creek than they are in sediments from Little Walnut above
Picnic Creek. This maybe attributable to the effects of pH. tn the undiluted
drainage from the tailings the pH may be sufficiently low that most available metals
are in solution. As the acid drainage ts neutralized with downstream travel, various
metals may leave solution at their own rates. This may explain the fact that
downstream sampling showed high metals in sediment, but low metals m water.
The downstream extent of metals in stream sediments is at least 5.9 stream
miles below the facility and 0.7 miles below the confluence of Little Walnut Creek
with Silva Creek. At that location zinc was still about 8 times background, white
copper was 3 times background. Although stream bed sediment sampling extends
the site boundary farther downstream than did water sampling, the limit of
contaminant travel at significant concentrations remains even farther downstream
some unknown distance.
s

-------
Staff also attempted to extend the site boundary eastward and upstream
beyond the storage reservoir formerly used to supply tne mill and now used for
swimming purposes. This result was achieved by demonstrating that contaminants
extend eastward from the mill site along the roadbed into the watershed of the
reservoir. This road is a U S. Forest Service road that is open to the public; although
it is not maintained, it is passable Soil samples were collected from the roadbed as
staff drove along the road Sample locations were chosen every 0.1 miles, as
measured with trie vehicle odometer. Samples were collected in front of the vehicle
prior to its passage over the sample location, thereby assuring that the investigation
team did not disturb the sample location or transport contamination from the site
to the samples. Results of this sampling effort are summarized in the table below.
ROADBED SEDIMENT SAMPLING RESULTS (ug/g)
location
head of tailings
southeast end of tailings
north of reservoir
south of reservoir
southwest of reservoir
Picnic Cr.(bkgd)
Silva Cr. (bkgd)
The above data indicate that metals are found in roadbed soil material at
concentrations significantly above background. Metals concentrations decline with
increasing distance from the mill site, a pattern which indicates that the site is the,
source of contamination. The greatest concentrations of all five metals was in th4
tailings themselves, as expected. Silver and lead concentrations on the roadbed
within the watershed of the reservoir were not significantly different from
background. Zinc and copper, however, remained elevated significantly above
background at three sampling locations within the reservoir watershed. These data
support extension of the site boundary eastward along the access road around the
swimming reservoir. The presence of site-derived contamination in the watershed
of the reservoir places the swimming hole downstream of the site. This establishes
recreation as a surface water use within three miles downstream of the site.
Surface water route investigations allowed extension of site boundaries S.9
miles downstream from the Cleveland Mill facility and eastward to include the
former water supply reservoir, now used for swimming. By extending the site
boundaries, recreation is established as a surface water use within three miles
downstream of the site.
Zn
7695"
Cu
136ff~
Pb
107F
&
As
er
2890
440
220
8.4
41
1430
120
41
1 6
97
620
95
40
1.2
11
980
110
45
1 6
9.1
140
43
16
08
3.1
80
22
16
0.8
3.3
Is

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GROUND WATER ROUTE
Aquifer of Concern
The aquifer of concern at this site consists of the Colorado Formation, various
igneous rocks, and alluvium, all of which are hydrologically connected. The
following discussion is taken from Trauger (1972) unless otherwise indicated.
Igneous rocks in the vicinity of the site are of Cretaceous and Tertiary ages
and include both intrusive and extrusive types (Trauger, Figure 2). The intrusives are
granitic dikes, sills, plugs, stocks, and laccoliths which have cut across or displaced
older geologic materials. They include quartz diorite, monzomte. and gabbro near
the Cleveland Mill site. Granitic rocks in this area are typically dense, relatively
impermeable, and nonwater-bearing except where deeply weathered or intensely
jointed. Dry holes are not uncommon. Typical yields to wells in intrusives range
from less than 1 gallon per minute (gpm) to more than 15 gpm. The higher water
yields are achieved where the material is deeply weathered or intensely jointed.
Extrusive rocks near the site are andesite breccias. Characteristics of these
materials range from dense to vesicular and from massive to well-jointed. These
formations have water-bearing properties similar to the intrusive igneous
formations (Trauger, Figure 2). Little water is found where the volcanic rock is
dense and massive, but yields up to 25 gpm may be attained where it is well-jointed
and vesicular
The Colorado Formation is of Upper Cretaceous age and may be as great as
1000 feet thick. It consists of marine clastic strata, including shales, sandstones,
conglomerates, and limestones. The Colorado Formation is locally water-bearing,
but yields are unpredictable. Some borings as deep as 300 feet are dry, while other.
wells are artesian and flow at the land surface. "Artesian flow, dry holes, low yield*,
and uncertain supplies are found in the same general area and in the same rock
formation" (Trauger, p. 39). This situation is further complicated because the
Colorado Formation has been locally intruded by igneous dikes, as described above.
"The Colorado Formation, inherently a poor aquifer, has been made poorer as a
result of compartmentatization by the dike system" fTrauger, p. 39). The Colorado
Formation usually will yield less than 2 gpm, and sometimes less than 0.5 gpm;
nevertheless, this is sufficient water for domestic and livestock needs.
The alluvium in the vicinity of the site consists of Holocene and Recent
floodplain and channel deposits of gravel and sand along Little Walnut and Silva
Creeks. The water table in the river valleys usually is near the land surface and the
coarse alluvium in these streams may contain appreciable amounts of water.
However, by itself the alluvium generally will not sustain large, prolonged yields
because the deposits are thin and the valleys are narrow. Individual wells may
sustain large yields of water on a seasonal basis, but not annually.
The Colorado Formation, igneous rocks, and the alluvium are hydrologically
connected and form a single aquifer of concern in the vicinity of the site. The
Colorado Formation is widespread at the land surface near the Cleveland Mill site
and in the watershed of Little Walnut Creek (Trauger, Figure 2). in several locations,
particularly evident in upland areas, the Colorado Formation is cut by igneous
intrusives. In river valleys the Colorado Formation and igneous dikes are covered by
a thin veneer of alluvium. The valleys of Little Walnut and Silva Creeks have been
excavated from the underlying Colorado Formation and its associated igneous
dikes. Therefore, alluvium along Little Walnut Creek is in direct contact with the
Colorado Formation (Trauger, Table 12, p. 143) and with subjacent igneous rocks
The generally coarse, permeable nature of the alluvium allows water to move
downward into underlying geologic materials that are sufficiently permeable to
accept the water. This is a principal soure of recharge to bedrock aquifers m the
vicinity of the site and throughout much of southwestern New Mexico (Trauger, pp
7

-------
53-54) The Colorado Formation includes sedimentary strata whose composition
varies from shales to conglomerates, with an associated wide range in
permeabilities. Similarly, igneous rocks have varying permeabilities depending on
the degree of weathering and |omtmg. Where alluvium overlies shale units within
the Colorado Formation, shallow alluvial ground water is often locally perched on
the shale (Trauger, Table 12. p. 143). However, ground water moves freely between
the alluvium and the bedrock where alluvial deposits overlie sandstones,
conglomerates, fractures, or other permeable zones in the Colorado Formation and
intruded igneous materials. Much of the water found in the Colorado Formation is
derived from recharge from the overlying saturated alluvium along streams such as
Little Walnut Creek
The hydrologic connection between the three geologic formations discussed
above is also evident in the water table map constructed by Trauger (Figure 3). This
map indicates a single, continuous water table surface at the Cleveland Mill site and
extending several miles to the southwest. This area includes the valleys of little
Walnut and Silva Creeks. This uppermost aquifer beneath the site exists under
water table conditions and is continuous across a variety of geologic units, including
the Colorado Formation, alluvium, and igneous intrusives and extrusives. There is
no evidence for regional hydrologic separation of waters contained within each of
these three geologic units.
The direction of ground water flow in this complex shallow aquifer is shown
by Trauger to be southwest near the facility, changing to south closer to Silver City
(Figure 3). This generally conforms with topography, as is expected in a water table
jaquifer.
Site Boundary
The site boundary relevant to potential ground water route targets is the
same as the site boundary for the surface water route. The surface water site
boundary applies for around water because the aquifer of concern includes the
alluvium beneath Little Walnut Creek and Silva Creek. These alluvial deposits are
recharged directly by surface water flows from the Cleveland Mill tailings.
Contamination originating on-site extends downstream in surface water and stream
sediments at least 0.7 miles below the confluence of Little Walnut Creek and Silva
Creek, and at least 5.9 stream mtles below the facility.
Water Well Inventory
In order to determine the population potentially at risk from contaminated
ground water, attempts were made to identify and locate water supply wells
tapping the aquifer of concern within thre« miles of the site, as described by the
above-mentioned boundaries. Information was obtained from Trauger (1972), the
files of the New Mexico State Engineer Office (SEO) and the EIO Water Supply
Section (WSS). EIO staff stationed at the Silver City Field Office (FFO) assisted
through their first-hand knowled9e of the area.
Despite the search of WSS files, no public water supply wells were identified
within a 3-mile radius of the extended site. All such supplies in the Silver City area
are located well to the east or south of the Cleveland Mill site. The aquifer at and
near the site is generally not capable of sustaining large water yields and it is not
surprising that public supplies are located elsewhere.
Nevertheless, a large number of private wells are located within the 3-mile
radius (Appendix I; Figure 1). Using drillers' logs, staff identified those water supply
wells which tap the aquifer of concern. Different formations are indicated as
Colorado Formation (Kc), alluvium (Qal), intrusives (TKi), and extrusives (TKab).This
part of the SIF also produced valuable data such as well depth, construction, and
use. Most of the wells are used solely for domestic purposes (D); many are also used


-------
tor livestock watering (S), and a few provide irrigation water (I) for gardens and
orchards
Targets
A total number of 337 private water wells were identified within the 3-mile
radius of the site. 300 wells provide domestic water to single families (300 x 3.8 s
1140 people). 11 are auxiliary domestic wells that supplement other supplies and
have no unique targets. 8 are domestic wells that serve more than one household
(22 households x 3 o * 83.6 people). One (1) well serves a transient population (no
targets). One (1) well serves an unknown number of trailers (at least 2 x 3.8 a 76
people) Two (2) otherwise domestic wells also are used for irrigation, but the
number of documented acres is only 6 (x 1.5 people per acre * 9 people). Five (5)
are livestock wells and do not have human targets. Six (6) wells were reported to be
dry holes and are not in use. Five (5) wells have other uses, such as municipal (non-
consumptive) or irrigation, or no use, and no confirmed targets.
Target Population
domestic 1140 + 83.6 + 7.6 * 1231.2
irrigation:	9
total.	1240.2 people
Ground Water Sampling
Ground water sampling was conducted during the SIF for the purpose of
documenting a release to ground water. Private wells belonging to Hughes, Hood<
Carson, and Vendrely were sampled. These wells are located along the valley of •
Little Walnut Creek downstream of the Cleveland Mill facility and in the probable -
path of contaminant travel. As discussed above, ground water flows to the
southwest and south. In addition, the investigation team sampled a well owned by
the U. S. Forest Service and located along Picnic Creek about 0.5 miles above the
confluence with contaminated Little Walnut Creek.
Results of ground water sampling at alt five locations are summarized in the
table below:.
GROUNO WATER SAMPLING RESULTS (ppm)
location	pH Zn	Cu	Pb	Ao	As
u£K(bkgd)	OT55	cTTbs	1	<
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The source of small concentrations of zinc in ground water samples cannot be
pinpointed with the data at hand. The Cleveland Mill is one possible source of zinc
that may be contaminating ground water with zinc. A second possible source is
steel casing and galvanized pipe used to construct the private wells in the area. For
example, tne Vendrely well is cased with steel pipe and the pump is hung with
galvanized pipe, a likely source of zinc. Leaching of zinc from these wells may be
occurring, causing zinc to appear in samples, while the ground water itself may have
only background concentrations
No copper, lead, silver, or arsenic was detected in any of the wells tested
Oe-ionized water was used during the investigation to prepare a field blank
This quafity control (QC) sample collected during the SIF indicated that no artificial
contamination of samples occurred and that the concentrations presented above
represent actual concentrations in ground water as sampled. The results of QC
sample analysis are presented in the table below:
quality control sample-ground water
location	date Zn	Cu	Pb	Ag	As
field blank 117W86 
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angles of the triangular cross-sections through use of trigonometric equivalencies
For an oblique triangle with angles A, B, C, and opposite sides a, b, c:
a2 a	• 2bc (cos A);
cos B s (c2 + a* - b2)/2ca;
cosC a (a^ + b2 - c2)/2ab, and
height (h) a bsm C.
Area of the triangle is then calculated as area (Z) * ah/2
Three such trianautar cross-sections were derived for each pile Distances (I)
between the measured"^cross-sections were measured with a steel tape. The
volumes (V) of tailings contained between two adjacent triangular cross-sections
was calculated as the product of length (distance between the two cross-sections)
and the mean area of the two cross-sections-
Vi a (Zi ~ Z2V2 x Li and V2 » (Z2 ~ Zj)/2 x I2.
The total volume of a pile was calculated as the sum of Vi and V2 The east side
tailings totalled 3,070 cubic yards (Figure 3), while the west side pile contained
9,299 cubic yards (Figure 4). Total tailings volume is 12,369 cubic yards.
The above calculation of tailings volume is a minimum estimate. To simplify
the overall problem and enable the above arithmetic, conservative values were used
for several factors. For example, the rounded southern ends of the piles were not
counted Length of the free face was measured from the top of the pile to the
drainage at the base, even though there may have been more tailings to an
unknown depth beneath the drainage. Similarly, there were uncounted heaps of
what appeared to be tailings material scattered about the mill area.
SUMMARY AND APPLICATION
Work conducted under this Site Inspection Follow-up investigation permits
several important conclusions to be drawn. Site boCndaries can be extended in two
directions. Contaminated surface water and stream sediment samples show that
the site boundary for ground water and surface water routes extends 5.9"stream
miles downstream from the facility. Contaminated roadbed sediment samples show
that the site boundary also extends eastward beyond the former water supply
reservoir. Little Walnut Creek is used for recreation downstream of the site. The
aquifer of concern was evaluated and described. Release to ground water of acid
tailings leachate has caused ground water contamination in the form of lowered pH
at the Hughes private well. As a result of the water well inventory, it was
determined that 337 wells draw from the aquifer of concern within a 3-mile radius
of the site. Thittranslates into a ground water target population of 1240.2 people.
The total volume of tailings at the facility is estimated to be 12,369 cubic yards.
The information gathered during the SIF will be used to document an HRS
package for the Cleveland Mill site. Documentation will include releases to ground
water and surface water, waste quantity calculations and waste toxicity and
persistence, and target evaluations.
REFERENCE
Trauger, F. 0. 1972. Water resources and general geology of Grant County, New
Mexico. Hydrologic Report No. 2- Nei^Wexico State Bureau of Mines and
Mineral Resources. 211 pp. (dmkcktA)

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Cleveland Mill
Mining Waste NPL Site Summary Report
Reference 2
Excerpts from the Preliminary Health Assessment, Cleveland Mill Site,
Silver City, New Mexico; Agency for Toxic Substances and Disease Registry,
U.S. Public Health Service;
May 9, 1990

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CLEVELAND MILL SITE
SILVER CITY, GRANT COUNTY, NEW MEXICO
CERCLIS NO. NMD981155930
MAY 9 1930
¦r
*llC
r*:x:r Si';
I [oaltli S.


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SUMMARY
The Cleveland Mill Sice, a 5- co LO-acra Update 7 National Priorities Lisc
sice, is located 5 miles northeast of Silver City, Crant County, New
Mexico. The inactive abandoned mining site contains approximately 12,000
cubic yards of mine tailings. The mine tailings, groundwater, surface
water, sediment, and road surface in the site vicinity have elevated
levels of arsenic, copper, lead, silver, and zinc. Environmental
monitoring data are limited, and whether humans are being exposed co
site-associated metals at levels of probable public health concern is
uncertain. The major pathways of hunan exposure to site-associated mecals
include ingestion of contaminated food chain entities (in particular fish
from Little Walnut Creek and the pond north of the site), inhalation of
re-entrained mine-tailing wastes, and ingestion or dermal absorption of
soil, mine tailings, surface water, and groundwater containing elevated
levels of metals. On the basis of preliminary sampling results, the sice
is concluded to pose a potential public health concern.
BACKGROUND
A. Site Description and History
The Cleveland Mill Site (CMS), consisting of 5 to 10 acres located about 5
miles northeast of Silver City, Grant County, New Mexico, is an Update 7
National Priorities List (NFL) slc« (see Figure 1). Tailings from the
mill were transported via a slurry pipeline and deposited on the sloping
side of a small valley. The ore-processlng facility (gravity separation
following crushing) was abandoned In the 1920s.
Tailings piles, with an estlaated volume of 12,000 cubic yards, are
uncovered, unstablllzed, and unllned. Mine tailings consist of processed
(crushed) ore and rock. Leachate froa the alne-talllngs piles drains into
Little Valnuc Creek whose headwaters begin In tha vicinity of the tailings
piles.
Principal slte-assoeaitad metals of concern Include lead, silver, zinc,
copper, and arsanle. Tha copper, lead, and zinc are believed to exist in
the tailings as constituent of ore ainerels. Rain water percolating
through Che tailings reacts with sulfide producing aqueous complexes of
copper sulfate and zinc sulfate, which migrate froa the tailings in the
low pH drainage. Leachate froa the tailings gradually flows into surface
water. Although arsenic and lead were detected In surface water from
Little Valnut Creek, these contaalnants were found at much lover levels
than in the tailings. Most likely, these compounds fora Insoluble
compounds (lead sulfate and arsenlte and arsenate salts).
Page 1

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ENVIRONMENTAL CONTAMINATION
AND OTHER HAZARDS
A On-Site and Off-Site Contaaination
Groundwater 1985
Contaminant
Arsenic
Copper
Lead
Silver
Zinc
Maxiaua Concentration
(Reported as parts per billion [ppb])
Background
<5
<50
<10
<1
650
Residential Veils
<5
<50
<10
<1
1.700
Contaainanc
Arsenic
Copper
Lead
Stiver
Zinc
Sediment 1986
Maxiaua Concentration
(Reported ac parts per billion [ppb])''
Background
3.300
43,000
22,000
900
140,000
Little tfalnut Creek
Above Sllva Creek
17,000
1,160,000
93,000
13,000
5,660,000
Contaainanc
Coppar
Lead
Zitvc
Surface Water
Maxiaua Concentration
(Reported as parts per billion [ppb])
Background
<50
10
<50
Little Valnut Creek
Above Sllva Creek
11,000
40
110,000
Paga 3

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pathways analyses
A. Environmental Pathways
L Groundwater
The aquifer Located in Che sice vicinity consists of the Colorado
Formation, various igneous rocks, and alluvium, all of which are
hydrologically linked. Tailings piles from Che Cleveland Mill are located
in an area chat serves to recharge che alluvial aquifer underlying che
site. The local alluvial aquifer consists of coarse, permeable materials
overlying and hydrologically connected to the bedrock aquifer. Bedrock
within che sita vicinity consists of Upper Cretaceous marine strata
(shales, sandstones, conglomerates, and limestones) and vesicular and
Jointed igneous rocks. The vater cable within che floodplains of local
watercourses (Little Walnut and Silva Creeks) can be vichin 14 feet of che
ground surface.
Groundwater contaminants nay move in a downward direction and may impact
che groundwater quality of the bedrock aquifer. Permeability of bedrock
within che sice's vicinity is minimal except in cases where bedrock is
highly fractured, jointed, or weathered.
A total of 337 private wells have been Identified wichin a 3-mile radius
of the site. Locally, groundwater is used for potable domestic purposes,
irrigation, and watering of cattle. The 337 identified wells are used for
the following purposes:
USE OF GROUNDWATER WELLS IN SITE AREA
Use	Number of Wells
Single Family Domestic
298
Auxiliary Supply
11
Serve MuLtlple Households
3
Dry Uells
6
Municipal (Noneonsuaptlve)
5
Transient Population
1
Livestock
5
Domestic and Irrigation
2
Multiple Trailers
I
Uichln a 3-mile radius of the site, there are IS groundwater wells that
are 20 feet or less deep. The U. S. Forest Service well is the nearest
private veil; however, this well is located upgradlent 'of the site. The
nearest residential well (Hughes well) Is 1.7 stress miles downgradlent of
che site and within 200 feet of Little Walnut Creek. Analyses of
groundwater samples collected from the Hughes well indicate higher levels
of zinc and a lover pK than those found In groundwater samples collected
from the Forest Service well upgradlent of site.
Page 5

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2.	Surface Water
The sice lies within 100 yards of the headwaters for Little Walnut Creek
Contaminants from the sine tailings have Impacted Little Valnut Creek,
which is used for recreational purposes, including fishing and swimmLng
Elevaced levels of copper and zinc have been detected as far as 5 9 miles
from the sice.
Approximately 200 feet northwest of the mine-tailings piles, a pond has
formed on the north side of a small dam. The pond was used to supply
water for industrial purposes during operation of the mine. Surface-vacer
and sediment samples were not collected from this pond; therefore, it is
noc possible at this time to assess the public health implications of the
pond's use for recreational purposes.
3.	Soil
Soil contaminants may be transported to off-site areas via water and wind
erosion. Because of the steep slopes of the tailings piles and the small
particle size of the mine tailings, wind- and water-related soil erosion
is likely. Analyses of sediment samples collected froa the Little Walnut'
Creek indicate that mine tailings have been transported at least 5.9 miles
downstream.
4.	Air
Air monitoring was not conducted during preliminary site Investigations
Nine tailings consist of finely crushed rock, which may be a source of
fugitive dust during windy weather. Winds may transport mine callings
into areas south of the site, including residential areas and
cattle-grazing areas located south and downgradient of the site.
5.	Food Chain
Contaminants in groundwater, surface water, sediments, soil, and mine
callings may bloaccuaulata in food chain entitles, such as crops,
livestock, game animals, and fish. Livestock and game are unlikely to
have direct contact with mine tailings, since the tailings are located on
very steeply sldad slopes and the tailings piles are noc vegetated. No
consumable wild planes were noted in the site area during the site visit
Surface*water and sediment samples froa the pond located near the site
were not collected for analysis; therefore, it Is riot possible to assess
the impact of constituents from the pond on local wildlife, specifically
edible fish species. Contaminant levels in surfaca-water and sediment
samples collected from Little Valnut Creek were sufficiently high to cause
concern that site contaminants may be bloaccusulated by edible fish.
Although Information In sits documents indicate that Little Valnut Creek
does support recreational fishing activities, the creek was dry during che
ATSDR site visit.
Page 6

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B. Human Exposure Pathways
I Groundwater
Human exposure via deriaaL contact with, and ingestion or inhalation of,
groundwater contaminants may result from use of contaminated groundwater
for domestic, industrial, and agricultural purposes. Continued leaching
and migration of mine-tailings contaminants may eventually affect the
groundwater quality of private wells within the site area. Results of
limited groundwater sampling have shown elevated levels of zinc, but noc
at levels of probable human health concern. Although an elevated level of
zinc was detected ac the Hughes well (1,700 ppb), this level is still weLL
below the U.S. Environmental Protection Agency (EPA) Secondary Maximum
Contaminant Level (SMCL) for drinking water of 3,000 ppb. The SMCL for
zinc was established to protect the aesthetic qualities of drinking water
and is related to public acceptance of the water and noc healch-based
Information.
2.	Surface Water
Surface water obtained from local sources 1s not used for human drinking.'
water within the site vicinity, although surface waters are used for
watering cattle. No surface-water Intakes are within a 5-mile radius of'
the site.
Human contact with surface water and dermal absorption of site-related
contaminants may occur because Little tfalnut Creek and the pond located
near the site are used for recreational activities, including swimming,
wading, and fishing.
3.	Soil
Since access to the site is unrestricted, unauthorized personnel who
trespass may con* in contact with soli and mine tailings containing high
levels of aet&ls. Humans may be exposed to metals in off-site soil via
dermal contact vlth, oc ingestion and inhalation of, dusts, especially
considering use of the site vicinity for recreational activities. Small
children may play In the site area; hovever, the frequency of these
activities is expected to be minimized because of the site's remote
location and because accessibility to the site requires travel up a
steeply graded, unpaved Forest Service road.
U. Food Chain
Another potential pathway for human exposure is through the ingestion of
food chain entitles that may have bioaccuaulated site-related
contaminants. If the pond adjacent to the site has contaminated surface
water or sediment, fish may bloaccumulate these contaminants. Persons who
Ingest contaminated fish may be exposed to these contaminants.
Page 7

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PUBLIC HEALTH IMPLICATIONS
The Cleveland Mill Site (CMS) is a potential public health threat because
mine tailings with elevated levels of metals may unpact local surface
water, groundwater, air, sediments. soil, and biota. Available sampling
results indicate that metals have migrated to off-site areas and have
impacted groundwater and surface water quality, although levels of metals
ui groundwater samples collected fron wells upgradient and downgradient of
the site were below those of probable public health concern.
Groundwater
The mose recent groundwater monitoring data (1984) indicate downgradient
concentrations were higher than those detected upgradient of the site.
Detected zinc levels in off-site private wells were below the EPA SMCL and
belov levels of probable public health concern. From Information
available to dace, groundwater does not appear to serve a* a pathway for
human exposure to sice contaminants.
Air
rtina tailings at the CMS contain elevated levels of arsenic, cadmium,
copper, lead, and line. During on-site recreational activities or
remediation of the site, soil-disturbing activities could lead to an
Increase of suspended dusts and airborne contaminants. Entrained
oine-tailings dusts may decrease air quality and Impact nearby residents
Additional monitoring data arc needed before the public health
implications of this exposure pathway can be evaluated.
Soil
Although on-site and o£f-site soils contained elevated lev«Ls of metals,
the human exposure pathway of concern for soil is inhalation. Because the
site is remote, site trespassers probably will not be within the age range
most likely to ingest soil (1-6 years old).
Food Chain
Fish in Little Walnut Creek or the pond north of the site may
bioaccumulate sediment ox surface-water contaminants. Bioaccuaulation of
contaminants from the sice say result in contamination of these potential
food sources; without analytic results of edible fish tissue, however, it
is not possible to assess the health impacca of fish consumption.
A specific discussion on Che contaminants of probable public health
concern at the CMS follows.
Page I

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Arsenic
Human exposure to arsenic is possible through three major pathways,
ingestion, inhaLation, and probably less importantly, dermal absorption
Common effects from Ingestion of arsenic Include irritation of the
digestive tract leading to abdominal pain, nausea, vomiting, and
diarrhea. Ingestion of inorganic arsenic, the form most likely found ac
CMS, also causes a pattern of skin abnormalities such as dark and light
spocs on the skin and small "corns" on the palms, soles, and trunk.
Although changes in the skin are not considered to be a health concern,
some of the corns nay progress to skin cancer. Other health effects of
arsenic ingestion Include an Increased risk of liver, bladder, kidney, and
lung cancer. Long-Cera exposure (greater than 14 days) to inorganic
arsenic at levels as lov as 20 ug/kg/day may result in cases of mild
health effects. EPA estimates that a dose of 1 ug/kg/day of arsenic
corresponds to a cancer risk of l.S X 10 (3).
Inhalation exposure to arsenic dusts may produce the sane health effects
as those experienced after oral exposure. The inhalation exposure route
is more likely to increase the risk of lung cancer than are ingestion
exposures. Arsenic air concentrations of about 200 ug/n have been
associated with irritation of the nose, throat, and exposed skin (2).
Dermal exposure to arsenic-containing compounds may result in mild to
severe Irritation of the skin, eyes, or throat. No reliable dose
estimates are available on the exposure level* at which these effects
begin to appear.
Cadmium
Humans may be exposed to cadslua at the CHS either by ingesting
contaminated soil, nine tailings, and fish or by inhaling contaminated
dusts. Only a very small percentage (l%-5%) of Ingested cadmium is
absorbed into the blood; however, much larger percentage (301-SOI) of
inhaled cadmium is absorbed. Once cadmium enters the body it is very
strongly retained (4).
Ingested cadmium say result In damage to the kidneys and may cause
hypertension. Cadmium compounds have not been observed to cause
significant health effects when exposure is through the dermal route.
Long-term inhalation exposures to eadaiua at levels of 100 ug/m3 may
increase the risk of chronic obstructive pulmonary disease and kidney
toxicity. Lifelong inhalation of air containing 1 ug/m3 may be associated
with a risk of lung cancer of about 2 In 1000. A proposed reference dose
(a daily dose that is estimated to be without appreciable human health
risk) of 5 X 10-4 ng/kg/day for oral exposure is currently under review
(4).
Page 9

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Lead
Human exposure co lead ac che CMS may occur through evo major pathways
ingestion of contaminated soli, mine callings, and fish, or Inhalation of
airborne contaminated dusts. Children are especially susceptible to che
health effects of lead exposure. Low levels of lead exposure may cause
decreased growth and intelligence quotient (IQ) scores. Low levels of
lead exposure may also cause hypertension in middle-aged men Pregnane
women exposed to lead may transfer lead to the fetus, which may result in
preterm birth, reduced birth weight, and decreased IQ in che infant (5)
Human exposure to lead through the inhalation of lead-contaminated dust or
lead fumes may result in the same health effects as those experienced
through ingestion exposure. Without air monitoring data, ATSDR cannot
determine whether air levels of lead pose a potential public health
concern (EPA's National Primary and Secondary Ambient Air Quality
S candards for lead are 1.5 ug/m ).
The Centers for Dlseasa Control (CDC) has cautioned that concentrations of
lead in residential soil or dust greater than 500-1,000 pares per million
(ppm) could lead to elevated blood lead levels in children inhaling or
ingesting soil. Lead level* in excess of these values were found in
on-site mine callings and in tho components of che road surface (a mixture
of soil, rock, and mine tailings) Immediately surrounding the site. Sice
trespassers and those visiting the sit* vicinity may experience short-term
exposures; however, the remote nature of che sice should reduce che
likelihood of long-term exposures.
Zinc
Human exposure to zinc at the CHS may occur through two major pathways:
ingestion of contaminated soil, mine Callings, and groundwater, or
inhalation of airborne contaminated duac. The pathway of exposure
determines the type of health effects resulting from exposure to excess
levels of zinc.
The National Academy of Sciences (MAS) has esclmaced the recommended
dietary allowance (BOA) for zinc is IS mg per day. Long-term exposure co
excessive levels of sine (2.1 mg/kg/day) could resulc in copper deficiency
(6 and 7).
Zinc is excreted from the human body through che feces. Sweac also
contributes co che elimination of zinc.
Page 10

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CONCLUSIONS
Based on information reviewed, ATSOR concludes chat this site is of
potential health concern because of che potential risk to human health
resulting from possible exposure to hazardous substances ac concentrations
that ma/ result in adverse health effects. However, these findings are
preliminary and based on incomplete data. Without monitoring data for
on-site and off-site air, off-site soil, and surface water and sediment
from the pond north of the site, ATSDR cannot completely evaluate che
health Impacts of this site.
Available groundwater monitoring data indicate that metals have not
affected the water quality of private veils of residences located in che
site vicinity. On-site soli contamination may pose a direct concern for
human health since access to the site has not been restricted.
In accordance with CERCLA as amended, che Cleveland Hill Site, Grant
County, New Mexico, has been evaluated for appropriate follow-up wich
respect to health effects studies. Inasmuch as there la no extant
documentation or indication that human exposure to on-site contaminants is
occurring or has occurred in the past, this site is not being considered,,
for follow-up health studies at this time.
As additional information is received by ATSDR, such material will form
the basis for further assessment, as warranted, of site-specific public
health issues.
RECOMMENDATIONS
To protect human health, ATSDR recommends the following:
1.	Restrict public access to the abandoned sine shafts and other areas of
the site that may pose physical hsxards.
2.	Conduct a survey of wells vlthln 3 miles downgradient of the site to
identify those wells which may be impacted by the site.
3.	Continue to monitor the private walls serving the residences located
off-site to determine the public health impacts from continued use of
these potable water sources.
U. Conduct air monitoring to determine if mine-tailings wastes are a
source for fugitive dusts, and if they ere, to what extfent.
5.	Collect samples of sediment and surface water from the pond located
north of the site and analyze these samples for site-related contaminants
6.	If site remediation occurs. Include the following in the remediation
workplan:
Page 11

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Cleveland Mill
Mining Waste NPL Site Summary Report
Reference 3
Excerpts from the Hazard Ranking System Score Sheet
and Documentation for Cleveland Mill Site, Silver City, New Mexico;
Richard A. Rawlings; March 31, 1987

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National Priorities List
SuDerfurd hazardous -waste sua hated under the
Comprehensive Environmental Response Compensation, and liability Act 
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^0'_"
" OBSERVED RELEASE
Contaminants detected in surface water at the facility ordownhill from it (5
maximum)
Water samples collected from Little Walnut Creek which receives run-off from the
tailings pile
Copper • 11 ppm
Zmc- 110 ppm (Reference 2, page 2)
Rationale for attributing the contaminants to the facility:
1	Copper and zmc concentrations in water samples collected from Little Walnut
Creek are significantly (at least 200 and 2000 times respectively) above background
concentrations m the uncontaminated portions of Picnic and Silva Creeks
Background concentrations of copper and zinc in Picnic and Silva Creek water
samples were less than the 0 05 ppm detection limit (Reference 2, page 2)
2	The site is the only plausible source The tailings piles are within 100 yards of the
Continental Divide and virtually at the source of Little Walnut Creek Waste
material eroded from the tailings piles has been traced both visually and by sample
analyses to at least 5 9 miles downstream (Reference 2. pages 2 and 5)
The waste materials m the piles (Reference 3/Reference 2, page 6) and the
sediments m the stream beds both contain elevated concentrations of zmc, copper,
lead, silver and arsenic These concentrations are significantly above the
background levels (Reference 2, pages 5).
3	No other sources of contamination exist m the Little Walnut Creek drainage
Picnic Creek and Silva Creek, which both |Oin Little Walnut Creek, showed no
contamination (Reference 2, pages 2 and 5) above their confluences with Little
Walnut Creek This eliminates the possibility of contamination entering from these
drainages
4	The fact that numerous soil or sediment samples contained less than detectable
quantities of all metals.demonstrates that sample collection, handling and analysis
were not the sources of metals found m contaminated samples

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Cleveland Mill
Mining Waste NPL Site Summary Report
Reference 4
Telephone Communication Concerning Cleveland Mill;
From Mary Wolfe, SA1C, to Anne Schober, EPA; August 13,1990

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TELECOMMUNICATIONS
SUMMARY REPORT
SAIC Contact: Mary Wolfe Date: 8/13/90	Time: 4:21 p.m.
Made Call X Received Call	
Person(s) Contacted (Organization): Anne Schober (214) 655-6710
Subject: Cleveland Milt
Summary: The Health Assessment is complete. Remedial Investigation/Feasibility Study work is
scheduled to begin in the Fall of 1990. The State of New Mexico Environmental Improvement Section
will take the lead. Cost planning for the Remedial Investigation/Feasibility Study is underway. Money
should reach State by the end of March. There will be a cooperative agreement, and a Statement of
Work is being refined. Field work is expected to begin at the end of the year or early next year.

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