PB95-964409
EPA/ROD/R08-95/096
January 1995
EPA Superfund
Record of Decision:
Summitville Mine Superfund
Site (O.U. 1), Summitville, CO,
12/15/1994
-------
ADMINISTRATIVE RECORD
INTERIM RECORD OF DECISION
FOR THE
HEAP LEACH PAD
Summitville Mine Supeifund Site
Summitville, Colorado
-------
INTERIM RECORD OF DECISION
for the
HEAP LEACH PAD
Summitville Mine Superfund Site
Summitville, Colorado
DECLARATION FOR THE RECORD OF DECISION
Site Name and Location
Summitville Mine Superfund Site, Summitville, Rio Grande County, Colorado.
Statement of Basis and Purpose
This decision document presents the selected interim remedial action for reducing or eliminating acid
mine drainage (AMD) and cyanide contaminated waters from the Heap Leach Pad (HLP) at the
Summitville Mine Superfund Site in Rio Grande County, Colorado chosen in accordance with the
requirements of the Comprehensive Environmental Response, Compensation, and Liability Act of
1980 (CERCLA), 42 U.S.C. § 9601 et seq., as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA) and the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP)(40 CFR Part 300).
This decision document explains the basis and purpose of the selected interim remedy for the HLP
portion of the Summitville Minesite.
The State of Colorado Department of Public Health and Environment (CDPHE) concurs with the
selected interim remedial action.
Assessment of the Site
Interim remedial actions are appropriate "to protect human health and the environment from an
imminent threat in the short term, while a final remedial solution is being developed." ("Guide to
Developing Superfund No Action, Interim Action and Contingency Remedy RODs," EPA. OS WER
Publication 9355.3-02FS-3, April 1991). Actual or threatened releases of hazardous substances from
this Site, if not addressed by implementing the interim remedial action selected in this Interim
Record of Decision (TROD), may present imminent and substantial endangerment of public health,
welfare, or the environment
-------
Description of Selected Remedy
The interim remedial action for the HLP addresses the reduction or elimination of acid mine drainage
and cyanide contaminated waters from the Heap Leach Pad. The purpose of this interim remedial
action is to control the transport of cyanide and toxic metals from the Heap Leach Pad (HLP) into
Cropsy Creek and Wightman Fork.
This interim remedial action is anticipated to produce continued reduction of contaminated water
flows to the Alamosa Watershed. The results of the interim remedial action will be routinely
monitored to determine the additional actions needed at each portion of the Site to achieve the fina)
sitewide remediation goals.
The major components of the selected interim remedy include:
• Development and implementation of HLP solution collection system consisting of
injection/extraction wells installed in the HLP;
• Pumping and treating of the contaminated leachate;
• Short term biotreatment of waters, in-situ biotreatment of ore and leachate using,
cyanide-destroying bacteria;
• Grading, recontouring, capping and revegetating the HLP to reduce the volume of
water to be treated;
• Installation of a lined surge pond and a bioreactor using sulfate-reducing bacteria to
treat acid waters generated after the HLP is remediated; and
• Periodic monitoring of ground water for cyanide and/or metal concentrations.
This interim remedy is consistent with current or future activities to complete sitewide remediation
goals.
No changes have been made to the preferred alternative originally presented in the Heap Leach Pad
Proposed Plan. However, the sequence of numbering the alternatives in the ROD varies from that
of the Heap Leach Pad FFS because some of the Heap Leach Pad FFS alternatives were not retained
after the screening process. Therefore, Alternatives 5-3 through 5-6 of the IROD correspond to
Alternatives 5-4 through 5-7 of the Heap Leach Pad FFS, respectively.
-------
Statutory Declarations
This interim remedial action is protective of human health and the environment, complies with
Federal and State applicable or relevant and appropriate requirements (ARARs) for this interim
limited-scope action, and is cost effective. Although this interim action is not intended to
address fully the statutory mandate for permanence and treatment to the maximum extent
practicable, this interim action does utilize treatment and thus is in furtherance of that statutory
mandate. Because this action does not constitute the final remedy for the Site, the statutory
preference for remedies that employ treatment that reduces toxicity, mobility, or volume as a
principal element, although partially addressed in this remedy, will be addressed in the final
response action. Subsequent actions are planned to fully address the threats posed by the
conditions at this Site. Because this remedy will result in hazardous substances remaining on-
site above health-based levels, a review will be conducted to ensure that the interim remedy
continues to provide adequate protection of human health and the environment within five years
after commencement of the remedial action. Because this is an interim ROD, review of this Site
and of this remedy will be ongoing as the EPA continues to develop final remedial alternatives
for the Site.
William P. Yellowtail
Regional Administrator
U.S. Environmental Protection Agency, Region
December 15,1994
-------
TABLE OF CONTENTS
1.0 DECISION SUMMARY : 1
1.1 Site Name, Location, and Description 1
1.1.1 Climate 1
1.1.2 Topography . 1
1.1.3 Geology 2
1.1.4 Hydrogeology 3
1.1.5 Present Surrounding Land Use and Populations 4
1.2 Site History and Enforcement Activities 4
12.1 SiteHistory 4
122 Enforcement Activities
6
1.3 Community Participation
7
1.4 Scope and Role of Interim Remedial Action within Site Strategy
9
1.4.1 Remedial Action Objectives and Goals 15
1.5 Site Characteristics 16
1.5.1 Nature and Extent of Contamination 16
1.5.2 Contaminant Transport and Migration 24
1.5.3 HeapLeachPad 25
1.5.4 ARARs 25
1.6 Summary of Site Risks 38
1.6.1 Screening Ecological Risk Assessment 38
1.6.2 Environmental Risk Assessment 40
1.6.3 Human Health Risk Assessment 41
1.7 Description of Alternatives 42
1.7.1 Alternative 5-1: No Action .42
L7.2 Alternative 5-2: Pump and Treat/Recontour & Cap 42
1.7.3 Alternative 5-3: Injection-Extraction Wells/Pump & Treat/Biotreatment/
Recontour & Cap/Bioreactor 43
1.7.4 Alternative 5-4: Extraction Pumps & Underdrippers/Water
Rinse/Recontour & Cap 45
1.7.5 Alternative 5-5: Partial HLP Removal/Injection-Extraction Wells/Water
Rinse/Recontour & Cap
45
1.7.6 Alternative 5-6: Pump and Treat/Total HLP Removal/Ex situ Ore
Treatment/Disposal On-Site 46
1.8 Comparative Analysis of Alternatives 47
1.8.1 Criteria 1: Overall Protection of Human Health and the Environment
48
1.8.2 Criteria 2: Compliance with ARARS 48
-------
1.8.3 Criteria 3: Long-Term Effectiveness and Permanence 49
1.8.4 Criteria 4: Reduction of Toxicity, Mobility or Volume
: 49
1.8.5 Criteria 5: Short-Tenn Effectiveness 50
1.8.6 Criteria 6: Implementability 50
1.8.7 Criteria?: Cost 50
1.8.8 Criteria 8: State Acceptance 50
1.8.9 Criteria 9: Community Acceptance
: so
1.9 Selected Alternative 51
1.10 Statutory Detenninations 52
1.10.1 Protection of Human Health and the Environment 52
1.10.2 Compliance with Applicable or Relevant and Appropriate Requirements
52
1.10.3 Cost Effectiveness 53
1.10.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies to Maximum Extent Practicable and Preference for
Treatment as aPrincipal Element 53
2.0 RESPONSIVENESS SUMMARY 54
2.1 Responsiveness Summary Overview 54
2.2 Summary and Response to Heap Leach Pad Specific Comments 54
2.3 Summary and Response to General Comments 64
2.4 Summary and Response to ARARs Comments 79
2.5 Summary and Response to Reynolds and Chandler Adit Questions 84
3.0 REFERENCES ..; 92
u
-------
Table 1 •
Table 2 -
Table 3a-
TableSb-
Table 4-
Table 5 -
Table 6 -
Table 7 -
Table 8-
Table9-
Table 10 -
LIST OF TABLES
Copper Content - Site Contaminated Water
Cyanide Content - Site Contaminated Water
Site Surface Water and Treatment Plant Flow Rates
Site Surface Water and Treatment Plant Water Volume
Containment Content During High and Low Flow Periods
Copper Concentration at WJ. 5.5
Total Cyanide Concentration at W.F. 5.5
ARARs
Numeric Surface Water Quality Goals and ARARs
Heap Leach Pad Remedial Alternatives
Comparative Analysis of Alternatives
111
-------
LIST OF FIGURES
Figure 1- Area Map
Figure 2 - Mine Site Footprint
Figure 3 - Geology - Cropsy Valley Section
Figure 4 - Contaminated Surface Water Streams
Figure 5 - Alamosa River Stream Segment Classifications
IV
-------
1.0 DECISION SUMMARY
1.1 Site Name, Location, and Description
The Summitville Mine SuperfundSite is located about 25 miles south of Del Norte, Colorado, in
Rio Grande County (Figure 1). It is located within the San Juan Mountain Range of the Rocky
Mountains, approximately two miles east of the Continental Divide, at an average altitude of
11,500 feet The mine is positioned on the northeastern flank of South Mountain. The disturbed
area at the Site covers approximately 550 acres (Figure 2). On the north, the Site is bounded by
the deserted town of Summitville, and by Wightman Fork Creek. It is bounded by Cropsy Creek
to the east and the peak of South Mountain to the southwest The Site is located in the Rio
Grande Drainage Basin near the headwaters of the Alamosa River. Two tributaries drain the Site
- Wightman Fork Creek and Cropsy Creek. The confluence of Cropsy Creek and Wightman
Fork is located on the northeastern perimeter downstream of the Site. Wightman Fork Creek
drains into the Alamosa River approximately 4.5 miles below the Cropsy Creek confluence.
1.1.1 Climate
The Site climate is characterized by long cold winters and short cool summers. Winter snowfall
is heavy and thunderstorms are common in the summer. Temperatures range from a high of
70°F and a low of 17°F in the summer to a high of 40°F and a low of -258F in the winter. The
Site receives an average of 55 inches of precipitation annually, mostly in the form of snowfall
with annual evaporation at approximately 24 inches.
There is a relatively snow-free period of 5-6 months from May through October. This period is
regarded as the "construction season." Site access and operations during the rest of the year
requires a significant amount of snow removal. Continued water treatment and flow, or
meticulous winterization, is required to prevent water from freezing in the pipes.
1.1.2 Topography
Approximately 550 acres of the Site is comprised of heavily altered terrain due to mining
operations. The Site's pre-1870 topography consisted of upland surfaces, wetlands, and South
Mountain peak. The predominant Site ground cover was alpine tundra at the higher elevations
with coniferous forest and subalpine meadow hi the lower elevations. The mountains
surrounding the Site, including Cropsy Mountain to the south, are between 12,300 feet and
12,700 feet in elevation.
-------
The Wightman Fork drainage covers approximately 3.0 square miles upstream from the
Wightman Fork diversion. The catchment elevations range from 11,225 feet to 12,754 feet The
Cropsy Creek drainage area entails 0.85 square miles on the northeast slopes of the Cropsy
Mountain and the southern slopes of South Mountain. Elevations within this drainage range
from 12,578 feet down to 11,200 feet at the Cropsy Creek confluence with Wightman Fork.
Wightman Fork drains into the Alamosa River approximately 4.5 miles from the Cropsy Creek
confluence.
Disruption of the topography began on a Limited scale in 1870, with placer gold mining in
stream-formed alluvial deposits. This placer mining was followed by open cut mining on gold-
bearing quartz veins. Underground mining followed. As mining production depths increased,
several processing mills were constructed to handle the increased capacity and produce a
concentrate suitable for transit This initial mining phase lasted through 1890 and additional
underground mining from 1925 to 1940 resulted in surface deposition of waste rock near the adit
entrances. Additionally, piles of mill tailings were placed downgradient from the stamp mills and
the 1934 flotation-cyanidation mill.
Further surface disruption of the topography resulted from work in the late 1960's when
Wightman Fork was diverted north to allow construction of a tailings pond. With this new
impoundment, mill tailings were put on the Beaver Mud Dump (BMD) down to the Summitville
Dam Impoundment (SDI) (previously referred to as the Cleveland Cliffs Tailings Pond).
The most dramatic surface alterations started in 1984 with the construction of the mine pits and
dumps, formed as a result of Summitville Consolidated Mining Company, Inc.'s (SCMCI's) open
pit heap leach gold mine. The main topographical feature is the highwall of South Mountain.
This highwall is fractured and has a one to one (horizontal to vertical) slope.
1.1.3 Geology
Summitville is located near the margin of the Platoro-Summitville caldera complex. Rocks in
the mine area consist of South Mountain Quartz Latite Porphyry. The porphyry is underlain by
the Summitville Andesite. The contact between the latite and andesite is intrusive, faulted in
some areas and is nearly vertical. On the north side, the contact is fault-bounded by the
Missionary Fault South Mountain is bounded on the southwest by a large northwest-southeast
trending regional fault called the South Mountain Fault The South Mountain Quartz Latite
Porphyry is bounded to the west, on both sides of the South Mountain Fault, by slightly older
Park Creek Rhyodacite. It is overlain at higher elevations by erosional remnants of slightly
younger Cropsy Mountain Rhyolite.
South Mountain volcanic dome emplacement, alteration, and mineralization occurred in rapid
sequence approximately 22.5 million years ago. Magmatic, sulfate-laden water expulsed from
the quartz latite magmas was hot and highly acidic (pH*2, temperature of 250° C), and caused
-------
extensive alteration to the quartz latite. Alteration occurs in four sequential zones: the massive
vuggy silica zone, the quartz-alunite zone, the quartz-kaolinite zone, and the clay alteration zone.
The massive vuggy silica zone is often a highly porous zone in which all major elements but
silica and iron were leached by acidic solutions and replaced in places by excess silica. This
zone occurs in irregular pipes and lenticular pods, and generally shows greater vertical than
lateral continuity. The next outwardly occurring zone is the quartz-alunite zone, in which
feldspars of the quartz latite porphryry were replaced by alunite. This zone grades outward to a
thin quartz-kaolinite zone, which is not always present, and then into an ilh'te-montmorillonite-
chlorite zone hi which feldspar and biotite grains were replaced by illite and quartz, with lesser
kaolinite and montmorillonite. The quartz-alunite and clay alteration zones are the most
volumetrically significant Fine-grained pyrite is disseminated through the groundmass in all
zones.
Summitville mineralization is an example of epithermal Au-Ag-Cu mineralization associated
with advanced argillic alteration. Mixed magmatic and surface water (derived from snowmelt
and rainfall), less acidic and more reducing than the magmatic water that produced the alteration
zones, deposited metals and metallic sulfides at shallow (<1 km) depths. Mineralisation is
associated mostly with the porous vuggy silica zone, and occurs as covellite + luzonite + native
gold changing with depth to covellite + tennanite. Gold also occurs in a near-surface barite +
goethite + jarosite assemblage that crosscuts the vuggy silica zone.
Post-volcanic geologic processes have been largely erosional. The two major streams that drain
the Site, Cropsy Creek and Wightman Fork, tend to follow the .quartz latite/andesite contact
Numerous springs and seeps occur at this junction between the fractured quartz latite porphyry
aquifer and the underlying dense andesite aquitard.
Site cover material consists of topsoil, silt, clays, and gravel. The topsoil is described as
grey/brown/orange, non-plastic with a trace of roots and sand. Clays are of low to medium
plasticity with some gravel.
1.).4 Hydrogeology
Ground water at the Site is present as a series of intermittent, shallow, perched aquifers. Shallow
ground water occurs in surficial deposits consisting of colluviuni, "slope wash" alluvium and/or
glacial ground moraine and weathered parts of the Summitville Andesite. These shallow systems
eventually discharge to surface water. The upper perched aquifer system also contributes to the
ground water recharge of the fractured bedrock system. Numerous springs and seeps cover the
entire Minesite, the greatest number at the locus of the distal edge of the dome. Most of the
springs and seeps flow in direct response to precipitation, with high and low flows corresponding
to high and low flow of the surface water system hi the area.
-------
A natural surface water drainage system exists along the southern portion of the Summitville
Site. The surface water drainage system includes Cropsy Creek and Wightman Fork. Extensive
re-working of both drainage systems has been conducted
1.J.5 Present Surrounding Land Use and Populations
The Site is surrounded by National Forest Service land (Rio Grande National Forest). The
multiple-use designation of this land gives it a high level of desirability for snow mobiling, cross
country skiing, hiking, camping, horseback riding and picnicking. Additionally, logging activity
is on-going adjacent to Park Creek Road and other roads adjacent to the Site. During the summer
months, domestic cattle and sheep graze in the surrounding area and during the winter months,
the surrounding area is heavily used for hunting.
The distance to the nearest off-site building is 2.1 miles to the east The water from the Site
flows past the town of Jasper into Terrace Reservoir, both of which are recreational areas.
Private residences and a Phillips University Camp use water from wells adjacent to the Alamosa
River. Below the Terrace Reservoir, the river flows past the town of Capulin which contains two
municipal wells and many domestic wells. Throughout this drainage area, homes, farmsteads
and ranches depend upon alluvial wells or river water for potable or agricultural water
production. However, recent EPA analysis indicates that the Site has not impacted alluvial
drinking water supply wells. Additionally, water from the Alamosa River is used within the
Monte Vista Wildlife Refuge and in the La Jara Creek system through the Empire CanaL
12 Site History and Enforcement Activities
1.2.1 Site History
Placer gold was discovered in Wightman Gulch in the summer of 1870. The lode deposit was
found near the headwater in 1873 and by 1875, open cut workings had been established. The ore
consisted of native gold in vein quartz, reportedly associated with limonite and other ion oxides,
which comprised the surficial, oxidized zone of the deposit Because this zone reportedly
extended to 450 feet below the surface, adits and shafts had to be driven into the veins. There
was only minor production in the mine area from 1890 to 1925.
In 1897, the Reynolds Adit was driven into the Tewksbury vein, located below the central
portion of the contemporary Summitville pit The Adit was completed in 1906. Reports of
acidic water exiting the adit soon followed.
-------
A significant gold find occurred in 1926 when high grade ore was struck. From 1926 to 193 1,
864 tons of ore were extracted. The Reynolds Adit was rehabilitated to provide haulage and
development access. Plans were made to connect the Reynolds to the Iowa Adit, 540 vertical
feet above the Reynolds. This connection was completed in 1938. Iowa ores were then dropped
down to the Reynolds level for haulage. The Reynolds and the Iowa Adits also provided
drainage for the ipa*" workings.
A 1 00 ton-per-day flotation/cyanidation mill and gold retort was installed in 1 934. Records
indicate that dewatering filtrate from the flotation circuit was discharged directly into Wightman
Fork throughout the mid-1 930's.
In 1941, three tunnels were in operation: the Iowa, Narrow Gauge, and Reynolds. During World
War n, the government mandated the termination of mining of non-essential minerals to focus on
essential minerals needed for the war effort. Gold production ceased.
From 1943 to 1945, a high grade copper vein found hi the Narrow Gauge and Reynolds was
developed. By 1944, only the Narrow Gauge Tunnel was operating. In 1947, the Reynolds was
again rehabilitated. Approximately 4,000 feet of rail needed replacement due to deterioration
from acidic water. By 1949, the water flow discharge from the Reynolds ranged from 100-200
gallons per minute (gpm).
From 1950 to 1984, the minesite was the target of several exploration and underground
rehabilitation programs. Production of copper, gold, and silver was sporadic. An extensive
drilling program was conducted in the late 1970's and early 1980's to delineate a potentially
minable gold deposit
The underground and surface operations during the original discovery of gold to the early 1980's
resulted in surface deposition of waste rock near adit entrances and deposition of mill tailings
downgradient of the original mill, close to the south bank of the original Wightman Fork Creek.
An attempt to process ore to extract copper content in the late 1960's and early 1970's resulted in
a diversion of Wightman Fork from its original route to further north of the existing tailings,
construction of the SDI (1969) and deposition of mill tailings east of existing tailings piles.
During recent operations (1984-1991), Summitville Consolidated Mining Company Incorporated
(SCMCI), a wholly-owned subsidiary of Galactic Resources, Inc., developed the remaining
mineral reserves as a large tonnage open pit heap leach gold mine. Gold containing ore (9.7
million tons) was mined, crushed and heaped onto a constructed clay-and-synthetic-lined pad. A
solution containing 0.1-0.5% sodium cyanide was applied to crushed ore on the Heap Leach Pad
(HLP) and was allowed to percolate through the ore to leach out gold. The solution was then
pumped from the ore and gold was removed from the leachate with activated carbon. The
leaching solution was rejuvenated by restoring the target cyanide level and recycled through the
heap. Gold was stripped from the carbon, precipitated from the stripping solution, smelted to
make dore metal, and sold.
-------
The Summitville HLP is a "valley fill" design. This design differs from more widely employed
designs in that it is more of a lined depression, or rock filled pond, than a lined leaching "pad".
Utilization of a valley fill design usually results from topographic limitations that make
construction of a free draining pad difficult The process solution was pumped directly from the
HLP to the gold recovery plant The more common leach pad design enables water percolated
through ore to constantly drain to a "pregnant solution pond" outside of the HLP, rather than
being held in the same containment area as the crushed ore. The design of the HLP as a
continuous water containment structure prevents the natural drainage of water from the cyanide
bearing pad and complicates the closure of the ore pile. The HLP containment feature was
constructed in a portion of the valley occupied by Cropsy Creek. Cropsy Creek was moved to
allow construction of the HLP. After diversion of Cropsy Creek, a portion of the valley was .
enclosed by dikes. The area between the dikes was contoured and lined and became the HLP.
Open pit mining operations conducted by SCMCI did not expose standing ground water in the
mine pit Infiltration of surface water (derived from snowmelt and rainfall) through the pit may
have resulted in elevated dissolved metal concentration in the water draining from the Reynolds
Adit This trend is observed when compared to the available pre-open pit drainage data.
During the SCMCI operation, topsoil was stripped and placed into stockpiles. Other overburden
and waste material was used for road and dike construction, placed into the Cropsy Waste Pile
(CWP), placed in the North Pit Waste Dump, and placed over the historic mill tailings to form
the Beaver Mud Dump. Difficulties in processing some of the ore resulted in formation of the
Clay Ore Stockpile, near the present solution pumphouse location, and an in-pit stockpile.
Figure 2 illustrates these areas.
The last ore tonnage was placed on the HLP in October 1991. Addition of sodium cyanide to the
ore continued until March 1992. After mining operations were concluded, SCMCI proceeded
toward Site cleanup and closure by converting the gold recovery plant to a cyanide destruction
facility for HLP detoxification, converting the existing alkaline chlorination water treatment
plant to a sulfide precipitation process, and installing a treatment plant to process Reynolds Adit
drainage.
1.2.2 Enforcement Activities
In February 1991, after tracking rising concentrations of cadmium, copper, zinc and cyanide in
Wightman Fork, the State of Colorado cited SCMCI for violations of water quality legislation
and issued a Cease and Desist Order.
On December 3,1992, SCMCI declared bankruptcy and announced that financial support of Site
operations would not continue beyond December 15,1992. On December 16,1992 the EPA
Region VHI Emergency Response Branch, as a part of an Emergency Response Removal Action
(ERRA), began treating cyanide-contaminated leachate from the HLP and acid mine drainage
-------
(AMD) from three significant sources, the French Drain Sump, the Cropsy Waste Pile, and the
Reynolds Adit
Site operation oversight was undertaken by the United States Bureau of Reclamation (USBR)
under an inter-agency agreement with the EPA. In December 1992, Environmental Chemical
Corporation (ECC), under the direction of the USER, began conducting engineering evaluations
of the water treatment processes and subsequently began improvements to water treatment
processes and facilities.
The Site was added to the Superfund National Priorities List (NPL) on May 31,1994. The HLP
Focused Feasibility Study (FFS) was completed in August, 1994. The EPA Region Vm is
currently conducting a Potentially Responsible Party (PRP) search.
13 Community Participation
The Proposed Plans for the Summitville Minesite were released to the public in August 1994.
The Proposed Plans, the FFSs, and other documents hi the Administrative Record are available at
information repositories at the following locations: Del Norte Public Library located in Del
Norte, Colorado; the Conejos County Agricultural and Soil Conservation Service located in La
Jara, Colorado; and the EPA Superfund Records Center located in Denver, Colorado.
Public meetings were held in Alamosa, Colorado to present the Proposed Plans and to take
public comments. The comment period was extended 30 days to October 23,1994.
Highlights of community participation are summarized as follows:
• When EPA took over the Site hi December 1992;there was a great deal of public
interest, mostly from farmers downstream of the Site who were concerned that
their irrigation water would be contaminated. As EPA worked to reduce the
chance of a catastrophic discharge of hazardous substances and began more water
treatment at the Site, the farming community became satisfied that there was no
imminent danger of contaminating meg water supply. Since that time, there has
been less local pubric interest about the Site. The interest in the Site nationally
has been very high due to the media using Summitville as a "red flag" for the need
for mining reform.
In June 1993, a Superfund informational workshop was provided to the public hi
La Jara, Colorado.
• On August 2,1993, a public meeting was held in Alamosa, Colorado describing
alternatives for reducing acid mine drainage from the Cropsy Waste Pile, the
-------
Beaver Mud Dump, Summitville Dam Impoundment and the Mine Pits. An
Engineering Evaluation/Cost Assessment (EE/CA) fact sheet was published.
Public comment was taken until September 3,1993.
The Community Relations Plan for Summitville was written and distributed in
September 1993. The Community Relations Plan provides a guide for EPA's
community involvement program based on interviews with local citizens.
A Technical Assistance Grant (TAG) was awarded for the Site in February 1994.
This group is now well organized and has hired several consultants. The TAG
Group has been active in the area in an attempt to generate interest in the Site.
They have published regular Summitville columns in the Valley Courier
newspaper and have held informational meetings.
EPA held a briefing for Congressional Aides in May 1994.
Press releases have been written for the following:
Proposal to place the Site on the National Priorities List (NPL)
Listing on the NPL
Announcing meetings
Availability of materials
Comment periods
Availability of work through bid process
Bid awards
Status of work at the Site.
Five Site Status Updates have been written and distributed to over 200 interested
parties as well as a year end report for 1993.
Articles about the mine were written by local newspaper writers and appeared at
least weekly for the past year. Files of these newspaper articles are available in
the Community Relations office and will be placed in the information
repositories.
In December 1993, the EPA produced and distributed copies of videos of the
Summitville Minesite. One hundred fifty copies have been circulated to schools
and officials. The video gives an overview of the contamination at the Site, a
brief history of the Site, and a "video tour".
-------
1.4 Scope and Role of Interim Remedial Action within Site Strategy
The original mine permitted area includes 1,231 acres; the area referred to as the Site is
comprised of approximately 550 acres of land disturbed by historic as well as recent mining
activities. The most common type of contamination associated with production of a metal mine
such as Summitville is the formation and discharge of large volumes of acidic water. The acid
generation can occur either chemically or biologically; as part of the living processes of certain
microorganisms. The acid is formed chemically when water, such as rainfall or snowmelt, and
air come into contact with metallic sulfide ores. The sulfide (83) then reacts to form sulfuric acid
and sulfates. The sulfuric acid and sulfates react with the surrounding rock or soils to generate
the metal concentrations within the acidic water and is then known as Acid Mine Drainage
(AMD). This process continues as long as there is sulfide or sulfates, water, and air.
The primary metallic sulfides and secondary sulfates found at the Summitville Minesite are
pyrite (iron sulfide), alunite (potassium aluminum sulfate), and jarosite (potassium iron sulfate).
There are fourteen areas of concern at the Summitville Minesite including twelve which either
generate or may potentially generate AMD. The fourteen areas are briefly described below in
their general order of priority:
1. HEAP LEACH PAD (HLP): The HLP is approximately 55 acres in size and 127 feet
deep at its lowest point The Cropsy Creek was diverted around the HLP area and the
HLP was then constructed in the former Cropsy Creek drainage bed. The HLP is
underlain by a French Drain system and extends onto the toe of the CWP which is located
upgradient within the Cropsy Creek drainage bed. The leach pad liner is leaking, causing
the water within the French Drain to become contaminated with cyanide. The HLP
consists of ore containing high levels of metallic sulfides sitting in a vat of cyanide and
heavy metals contaminated water. In December of 1992, the EPA took over operations of
the Site water treatment plant to prevent overflow of the contaminated water to the
Wightman Fork and, ultimately, the Alamosa River during Spring runoff. Currently the
HLP is maintained at a pH of 9 to prevent the evolution of hydrogen cyanide gas. It is
currently proposed that the Heap be detoxified as one of four interim actions. This action
will also address the potential acidification of the heap once the cyanide is removed and a
high pH is no longer maintained. The former continuous overflow of AMD to the HLP
from the adjacent CWP is currently being addressed as discussed hi 3 below.
2. REYNOLDS ADIT SYSTEM: The Reynolds System is composed of the
underground workings which still exist under the large open Mine Pit excavated by
SCMCI, and the remaining adits which access those workings. The Adits include the
Reynolds, the Dexter Crosscut, the Chandler, and the Iowa. The Reynolds Adit is the
main adit which was driven to drain the workings and provide an access and haulage
route. The Dexter Crosscut, a drift branching westward from approximately 100 feet into
the Reynolds Adit, also provided drainage, access, and haulage. The Chandler Adit
accesses the upper areas of the underground workings at a higher elevation than the
-------
Reynolds Adit The Iowa Adit accesses even higher levels of the workings and areas near
the rim of the Mine Pit The Mine Pit was hydraulically connected to the Reynolds
System and contributed much of the AMD observed at the Reynolds Adit The EPA
operated an interim treatment plant to treat the average 120 gallons per minute (gpm) of
AMD which exited the Reynolds Adit
Based upon the estimated release of 44.5 percent of total copper loadings directly from
the Reynolds Adit, it was determined that plugging of this system be conducted as a time-
critical Removal action. A contract to plug the Reynolds Adit System was awarded on
October 4,1993 and work began on November 22,1993. After extensive technical
considerations, only the Reynolds and Chandler Adits were ultimately plugged The
Dexter Adit was found to terminate approximately 450 feet from its intersection with the
Reynolds so no plug was needed. Upon completion of the Reynolds plug, there was an
immediate decrease in flow and a 65 percent reduction in copper concentrations from the
Site overall. Copper loadings directly attributed to the Reynolds Adit were decreased by
97 percent
On May 25,1994, the Chandler Adit was discovered to be discharging high volumes of
water from porous/fractured rock surrounding the plug. The leak was initially estimated
at 340 gallons per minute (gpm) and peaked at 725 gpm in June 1994 with high
concentrations of metals and low pH. However, this new contaminant source produced
less flow and less copper concentrations than experienced from the Reynolds Adit system
during the previous year. Work to, fortify the Chandler plug was initiated in November
1994 and plug performance will be closely monitored through the 1995 spring runoff
season. Since November 20,1994, AMD exiting the Chandler has been treated through
the PITS Water Treatment Plant and no longer discharges directly to Wightman Fork.
3. CROPSY WASTE PILE (CWP): The CWP was composed of approximately 6.5
million tons of low grade ore, overburden, and waste rock excavated from the main Mine
Pit during SCMCI's mining operations. The CWP covered approximately 35 acres and
was piled as high as 120 feet from the bottom of the old Cropsy Creek drainage bed in
which it was placed. Although the CWP had been capped to prevent percolation of
snowmelt and rainfall, upward infiltration of ground water has begun the process of
acidifying the CWP and AMD discharges are occurring from the CWP. When the HLP
was extended onto the toe of the CWP, the French Drain system beneath the CWP was
severed from the system below the HLP. As a result, water backed up behind the liner of
the HLP into the CWP - saturating that part of the CWP and creating a 5 million gallon
reservoir of highly contaminated water within the bottom of the CWP.
To prevent the overflow of AMD into the HLP, it was determined that the CWP would be
addressed as a non-time-critical Removal action. During development of the Engineering
Evaluation/Cost Analysis report, it became apparent that the same response action would
also apply to the Summitville Dam Impoundment and Beaver Mud Dump, and that
10
-------
concurrent implementation would be cost effective. The response action selected in the
Action Memorandum #4 issued by EPA on September 24,1993 required consolidation of
the various waste piles within the Mine Pits. Because this work would require more than
one construction season to complete, the design and actual construction were phased.
Phase I work was initiated on October 1,1993 and concluded in February 1994. During
this time, approximately 927,000 cubic yards of the Cropsy Waste Pile was placed in the
Mine Pits. The waste materials were isolated from ground water by lining the surface of
the Mine Pits with impermeable material identified on-site. A protective layer of lime
kiln dust was placed on the liner prior to placement of the waste materials to neutralize
any AMD generated during this work.
Phase n work was initiated in August 1994. The Cropsy Waste Pile was completed in
November 1994 and the SDI/BMD are expected to be completed in December 1994.
Phase n will have moved an additional 3.5 million cubic yards of waste material to the
Mine Pits.
Since Phase IE removal action work had not begun, EPA evaluated the removal action
alternative selected in the Action Memo as one of its remedial alternatives for the CWP,
SDI, BMD and Mine pits. This alternative was ultimately selected as the interim
response action for those areas of the Site. This work will include construction of a final,
impermeable cap and vegetation of the "footprint" areas below the CWP, SDI, and BMD.
4. WIGHTMAN FORK, ALAMOSA RIVER, TERRACE RESERVOIR (OFF-
SITE): The release of large quantities of AMD from the Site have occurred since the
1870's when mining first began, though the concentrations have significantly increased
since the beginning of mining activities by SCMCI. Much of the AMD generated at the
Site finds its way into the Cropsy Creek or Wightman Fork creek, unless it is diverted for
treatment The Cropsy Creek flows into the Wightman Fork at the southeastern comer of
the Site. The Wightman Fork, located on the northern boundary of the Site, empties into
the Alamosa River approximately 4.5 miles from the Site. The Alamosa, in rum, flows
into the Terrace Reservoir about 18 miles from the Site. There are three small wetland
habitats along the Alamosa where several endangered species, including the bald eagle,
whooping crane, and peregrine falcon have been identified. The closest wetland is 1.8
miles form the Wightman Fork confluence. The other wetland areas are 42 and nine
miles downstream form the confluence. These wetlands are all upstream of the Terrace
Reservoir. Concerns regarding other water usage requirements, including drinking water
and farm irrigation needs, are being investigated.
5. BEAVER MUD DUMP (BMD): The BMD encompasses 15 acres and consists of
approximately 900,000 cubic yards of historic metallic sulfide tailings as well as
overburden from SCMCI's operations. It is located immediately adjacent to and south of
the Wightman Fork Creek and is a significant source of AMD. The BMD is also
11
-------
infiltrated by ground water and discharges AMD to the Summitville Dam Impoundment
This area is being addressed as part of the CWP Removal action and interim action.
6. SUMMITVILLE DAM IMPOUNDMENT (SDI): Formerly referred to as the
Cleveland Tailings pond, the SDI is a historic sulfide rich tailings pond located within the
former Wightman Fork drainage bed. The Wightman Fork was routed around the
impoundment While the Impoundment only contains about 133,000 cubic yards of
material, it is thought to be hydraulically connected to the Wightman Fork and, therefore,
providing AMD directly into the creek. This area is being addressed as part of the CWP
Removal action and interim remedial action.
7. FRENCH DRAIN SUMP: The French Drain is a collection system which was
constructed underneath the CWP and HLP to intercept and route ground water flowing
from seeps below these units (CWP and HLP) back into the diverted Cropsy Creek.
Because much of this ground water flows through the CWP or becomes contaminated
with cyanide when passing below the HLP, it is currently routed to the water treatment
systems or pumped directly into the HLP. While the French Drain is not itself a source
generating contaminants, it serves as a point source discharge for contaminated water in a
fashion similar to that of the Reynolds Adit system.
8. CLAY ORE STOCKPILE (Stockpile): The Stockpile is located just north of the
CWP and HLP border and was originally meant to be ore for placement on the HLP.
Because of its high clay content, SCMCI was unable to provide the special Handling
needed before the ore could be leached. The one million ton Stockpile was purposely
created because of its high content of metallic sulfides and is considered to be a source of
AMD.
9. MINE PITS: This is the location of the former orebody mined by SCMCI and the
location of the veins that were historically mined within the Summitville mining district
The 100-acre Mine Pit has consumed most of the underground'mine workings with the
exception of the Reynolds Adit System described above. This area was and is highly
mineralized and contains high concentrations of metallic sulfides. Approximately 70
million gallons of water (snow or rain) per year entered the Pit, passed through the
remaining underground workings, and exited as AMD from the Reynolds Adit, prior to
plugging. The Pit is the origin of the rock in each of the tailings areas on-site and the ore
in the HLP. This area is being addressed as part of the CWP Removal Action and interim
action. At this time, the Pit has been filled by the waste material and is free draining of
surface water.
10. THE NORTH WASTE DUMP (DUMP): This refers to a large area located north
of the Pit composed of waste rock and overburden from the Mine Pit It contains
relatively moderate amounts of metallic sulfides and is a potential source of AMD. The
northern portion of the dump, primarily the slope below the 11,580 bench, was reclaimed
12
-------
and upper portions of the dump were regraded with some subsoil and topsoil placement
during the 1991 operational season. Vegetation success has been limited due to high
wind exposure.
11. GOMPERTS PONDS: These are a series of small ponds, located approximately
400 feet north of the HLP, that contained severely acidic and toxic metals contaminated
water and sludges. The ponds were excavated and then covered with soils. It is unknown
if any sludges or contaminated soils remain where the ponds were. If so, this area is
another source of AMD.
12. ACID ROCK DRAINAGE SEEPS: There are over 48 potential acid rock drainage
seeps identified on the Site. These are areas where ground water naturally comes to the
surface though some may be a result of construction activities at the Site. The seeps have
not yet been evaluated to determine if they are an AMD source.
13. MINE SITE ROADS: Many of the roads at the Site were constructed with waste
rock from the Mine Pit The material in these roads has not yet been evaluated to
determine if they are an AMD source.
14. LAND APPLICATION AREAS: There are areas where cyanide contaminated
AMD was sprayed onto the soils as a treatment method. Aeration, as a result of spraying,
was meant to eliminate the cyanide contamination while the soils were supposed to
attenuate the metals. These areas have not yet been evaluated to determine if they are a
current AMD source.
Once these areas had been identified, the EPA was able to establish Remedial Action Objectives
(RAOs) for the overall Site. Pursuant to 40 CFR section 300.43 (e)(2)(i), the RAOs were
established to provide remedial goals for the Site and were developed in consideration of current
regulatory guidelines, compliance with ARARs, and other identified limiting factors. The
Sitewide RAOs for the Summitville Minesite are:
1. Reduce or eliminate deleterious quality water flow from the Summitville Minesite into
the Wightman Fork.
2. Reduce or eliminate the need for continued expenditures in water treatment for the
Summitville Minesite.
3. Reduce or eliminate the acid mine/rock drainage from the manmade sources on the
Summitville Minesite.
4. Reduce or eliminate any human health or adverse environmental effects from mining
operations downstream from the Site, to include the Alamosa River.
13
-------
5. Encourage early action and acceleration of the Superfund process for the Summitville
Site.
An analysis of metal loadings attributable to each of the AMD source areas resulted in the
development of five primary areas of focus. Many of these source areas are in drainages or are
located where large amounts of surface or ground water are available for continued generation of
AMD. The Cropsy-Wightman stream drainage system for the Site also serves as a way to
transport the generated AMD contaminants off-site. The table below illustrates the copper
loadings and flows from these drainage points as measured by SCMCI in July 1991. This
approach is also based on the water quality data regarding copper loading into Wightman Fork.
The table lists the contaminant sources, the yearly copper contribution to the creek from each
source, and the relative percentage loading of each source:.
CONTAMINANT SOURCES
SOURCE
Reynolds Adit
Cropsy Waste Pile
Heap Leach Pad
overflow potential
French Drain
Summitville Dam Impoundment/
Beaver Mud Dump
Other
TOTAL
POUNDS OF COPPER PER
YEAR
143,000
33,400
84,000
14,600
17,000
29,000
321,000
RELATIVE
44.5
10.4
26.2
4.5
5.3
9.0
100.0
Due to the size of the Site and extent of the contaminating the Sitewide interim remediation
activities are being addressed in five separate, though related actions. These five actions are:
Plugging the Reynolds and Chandler Adits
• Movement of the Cropsy (CWP), Summitville Dam Impoundment (SDI),
and Beaver Mud Dump (BMD)
Heap Leach Pad (HLP) Detoxification/Closure
• Sitewide Reclamation
14
-------
• Interim Water Treatment
The first action of the containment/isolation and stabilization project was the plugging of the
Reynolds and Chandler Adits. The second action is excavation of the CWP, Tailings Pond, and
BMD, with subsequent placement of this material into the Mine Pits. Both of these removal
actions are in progress under Emergency Response authority as discussed above.
The Phase HI work for CWP, SDI, and BMD, as well as the remaining three actions will be
conducted as interim remedial actions. The CWP, HLP, and Reclamation work are expected to
begin work during the 1995 construction season. The Water Treatment action will continue
without interruption though modifications in actual treatment processes may be implemented
during 1995.
The HLP interim remedy, developed under the EPA's FFS Analysis of Alternatives, addresses:
• Cropsy Waste Pile, Beaver Mud Dump, Summitville Dam Impoundment, Mine
Pits
• Heap Leach Pad
Interim Water Treatment
• . Sitewide Reclamation
This IROD addresses the reduction or elimination of dissolved metal contaminants, the
transportation of metal contaminants, and metal/cyanide complexes in surface water at the Site.
This interim remedial action is targeted to mitigate point sources as they materialize. The
remediation measures described hi this IROD are additions and modifications to the substantial
cleanup measures undertaken by EPA using Emergency Response Authorities.
1.4.1 Remedial Action Objectives and Goals
Specific HLP remedial objectives are confined to removal, containment or treatment of
contaminated materials and drainage from HLP including the remnant CWP. Remedial actions
will be implemented hi order to eliminate or mimmm metal and cyanide transport to the
Wightman Fork and the Alamosa River. The impacts of transport will be monitored in the
Alamosa River below the confluence with Wightman Fork.
15
-------
The interim remedial action objectives and goals for HLP are as follows:
1) To eliminate or minimize HLP impacts to aquatic receptors in Wightman Fork,
the Alamosa River and Terrace Reservoir.
2) To eliminate or minimize the need for continued water treatment at the HLP.
3) To reduce or control HLP drainage so that the Alamosa River will continue to be
usable for agriculture in the San Luis Valley.
4) To reduce or control HLP drainage so that human health will continue to be
protected from releases from HLP.
5) To implement interim remedial action at HLP in an accelerated manner,
preferably within two years of signing the IROD.
The remedial action objectives and goals given above are listed in the order of immediate need.
This priority is based on the current conditions at the Site. The Emergency Response Actions at
the Site have reduced the imminent threat of excess cyanide release and catastrophic failure of
the HLP as long as control measures remain in place, primarily water treatment Pilot studies
using fresh rinse water indicate that continued recirculation of clean water through the HLP is
capable of reducing the cyanide levels to the point where it is no longer a threat
1.5 Site Characteristics
1.5.1 -Nature and Extent of Contamination
The EPA (1992) identified the Contaminants of Potential Concern (COPC) based on elevated
concentration and potential toxicity of mobilized chemicals. The COPC will be finalized upon
completion of the Baseline Risk Assessment These concentrations were compared to Site-
specific background levels, which were determined by standard statistical analysis (Morrison
Knudsen Corp., 1994). Potential adverse effects on human health and the welfare of wildlife
were preliminarily assessed (EPA, 1992). The COPC identified for the Site are copper,
raHmiiim., chromium VI, lead, silver, zinc, arsenic, aluminum, iron, mercury, manganese, and
cyanide.
All of these contaminants, except cyanide, are found at the Site in naturally occurring minerals
and compounds. They are made soluble during the AMD-generating chemical process. The
AMD process is accelerated by the "lining activities which took place at the Site.
1.5.1.1 Acid Mine Drainage
At Summitville, mining activities resulted in additional sulfidic material surface area available
for contact with oxygen and water. Air and water contact with the additional surface area
16
-------
provided by broken rock accelerates oxidation of minerals and creation of low pH drainage. This
drainage water is high in acidity, sulfate (S04) ions, and dissolved metals.
AMD water contributes metal loads to Wightman Fork and the Alamosa River. This creates
adverse conditions preventing the growth and maintenance of a healthy aquatic ecosystem.
These adverse effects have been noted in various studies of water quality of Wightman Fork and
the Alamosa River.
1.5.1.2 Water Containing Cyanide
Commercially manufactured sodium cyanide (NaCN) was used at the Site for extracting precious
metals from ore grade materials. Cyanide has been used for this purpose in the mining industry
since the late 1800's. Cyanide is found either in simple form or in combination with other
elements. Simple cyanide forms designated as "free" cyanide are the cyanide radical, CN", and
hydrogen cyanide, HCN. Cyanide also combines or complexes with alkali metal ions, heavy
metal ions, and transition elements. The complex cyanide bonding is very strong, moderately
strong, or weak (defined by tendency to disassociate in an acidic environment). Presence of
excess hydrogen ions (acid) will lead to the formation of HCN, depending on the strength of the
metal/cyanide bond.
Cyanide content is found in residual process water contained in the HLP. The predominant form
of cyanide in solution is a Weak Acid Dissociable (WAD) complex (complex that has a
moderately strong bond and dissociates at a pH of 4.5 or greater) with copper. Complexes with
other elements - silver, sulfur, gold, iron and others - are also present Thiocyanate (SCN) is
present in significant quantities. The tbiocyanates may migrate through the water treatment train
into Wightman Fork. The pH of contained residual process water within the HLP averages about
9,3.
Leaks in the HLP containment liner result in the presence of cyanide in drainage that surfaces
downgradient of the HLP. These drainage streams (from the Valley Center Drain, and several
seeps in and below HLP Dike 1) are mixtures of residual process water, AMD, and ground water.
The AMD portion results in low pH (2.5 - 35), and cyanide exists as either a metal/cyanide
complex (primarily with copper), or as free cyanide (HCN)- These streams are routed to the
French Drain Sump to prevent release to Wightman Fork and Alamosa River drainages. The
water is pumped to the HLP and mixed with residual process water, or treated separately.
1.5.1.3 Description of Impacted Water
Tables 1-6 summarize data collected during water monitoring before treatment and during
discharge of surface water to Wightman Fork. The tables include recordings of copper and
cyanide loadings from May 1993 through June 1994. During this period, monitoring emphasis
was given to copper and cyanide because these were the chemicals of highest concentration
during the ERRA. There was also a concern because of the potential toxicity of cyanide.
17
-------
Table 1 shows data representing the copper load (Ibs.) transported by the Site water. The first
group exhibits copper load from water pumped from the French Drain (FD) Sump. This sump
contains water from the Valley Center Drain (VCD) and AMD seeps.
The second data group within Table 1 illustrates the copper concentration of water contained in
the HLP. This includes water pumped from the FD Sump, water that surfaced at the toe of the
CWP, and process water contained in the HLP. All water in the HLP is treated to remove
cyanide and copper, as well as other metals, before release to Wightman Fork.
The underground workings section presents data on copper load that was transported by water
exiting from the Reynolds Adit and the Chandler Adit Also shown is the amount of copper
removed through treatment at the Portable Interim Treatment System (PITS). The PITS treated
water exiting the Reynolds Adit, the Iowa Adit, and some contaminant surface runoff. The plant
was deactivated after the Reynolds Adit plug was completed.
The remaining sections of the table present the copper content of surface water discharged into
Wightman Fork during mis time period. These include water from Cropsy Creek, seep LPD-2
(which feeds into Cropsy Creek), and Pond P-4 (a sediment pond that receives surface runoff
from the mine pit area, haul roads, and other runoff). Other streams that contributed copper load
to Wightman Fork include drainage from the Summitville Dam Impoundment (SDI), the North
Pit Waste Dump (NPWD), the Clay Ore Stockpile, and treatment plant effluent
Also shown are the pounds of copper that would have been added to Wightman Fork if water had
flowed into Wightman without treatment Annual totals from July 1993 to June 1994 are given to
the right of monthly totals. The twelve month period, July 1993 through June 1994, represents
the time frame when existing treatment facilities utilized maximum capacity.
Table 2 shows monitored cyanide loading (Ibs.) or the potential for cyanide loading to Wightman
Fork during the same period
Table 3a shows monitored flow rate for streams which are capable of carrying contaminant load
to Wightman Fork. High and low flow rates illustrate seasonal fluctuations. Combined monthly
totals illustrate potentially required treatment volumes.
Table 3b shows the total gallons for streams capable of carrying contaminant load to Wightman
Fork. This table also shows the treatment plant capacity measured in total gallons.
Table 4 shows other monitored constituents (manganese and iron) that should be taken into
consideration in the selection of treatment processes. Manganese removal to <1 .mg/liter is
necessary before cyanide destruction can take place. Significant iron content can produce sludge
volumes that affect plant efficiency.
18
-------
Tables 5 and 6 show copper and cyanide concentrations monitored at station WF 5.5 on
Wightinan Fork from May 1993 through June 1994.
General descriptions of monitored surface water affected by conditions at the Site are given
below. Figure 4 shows contaminated surface water streams.
Stream A - The Vallev Center Drain CVCD\
General: Comprised of drainage from the CWP, ground water from beneath the HLP,
and leakage from HLP containment, Contains cyanide as a result of leakage from the
HLP. CWP drainage contributes low pH and elevated metals.
Volume: Significant flow throughout the year. Peak flow is concurrent with spring
snowmelL High flow (78 gpm)recorded in April 1994; low flow (57 gpm) was recorded
in June 1993.
Loading: Based on copper as the indicator, the VCD ranked as the 4th highest peak flow
carrier of metals. 8,473 Ibs. of copper dissolved hi solution were transported by drainage
from July 1993 through June 1994.
Stream B - Cropsy Waste Pile Drainage
General: Comprised of ground water flow from seeps and upgradient drainage through
colluvium and alluvium (Geraghty & Miller, 1992). Includes precipitation (snowmelt
and rain fall) infiltrating through mine waste materials. Significant aluminum content
effects must be considered when selecting a treatment process. Volume and makeup are
expected to materially change with planned relocation of CWP materials.
Volume: Seasonal release to the surface at the toe of the CWP. Year round contribution
to the VCD. High flow (364 gpm) recorded in May 1993. Surface flow was not
observed at the toe of the CWP between January - April 1994.
Loading: Based on copper as the indicator, water surfacing at the toe of the CWP is the
second highest peak carrier of metals. 23,305 Ibs. of copper dissolved in solution were
transported by drainage from July 1993 through June 1994 (includes water sent to the
CWTP).
Stream C - Drainage from Underground Workings
General: Comprised of ground water and precipitation (snowmelt and rainfall)
infiltrating the mine pit area. These infiltrating waters draining through mineralized rock
into the remaining underground workings have historically surfaced as flow from the
Reynolds Adit. Comparatively less water volume drams from the Iowa Adit The
19
-------
Reynolds and Chandler adits have been plugged. The long-term effects of plugging the
Reynolds Adit in February 1994 and Chandler Adit in March 1994, and the consequent
rise in the South Mountain water table have not been determined. In May 1994, an AMD
stream developed as discharge from the Chandler Adit It has been observed that the
water is flowing between the top of the plug and the roof of the adit (Abel, pers. comm.,
1994). Peak flow from the Chandler Adit leak in June 1994 was 661 gpm with a copper
concentration of 409.40 mg/1 and a pH of 2.16, determined by sampling the stream just
outside the adit entrance. This was almost "instantaneous" (the discharge increased from
0 gpm to 661 gpm in 11 days), indicating a direct relationship between the rise in the
South Mountain water table and the rilling of the adit system with water. By the end of
July 1994, the flow of the AMD stream decreased to 130 gpm with a copper content of
268 mg/1 and a pH of 2.30. Eventual volume of AMD that may require treatment is
unknown. Corrective measures are planned.
Volume: Significant flow throughout the year. High flow from the Reynolds Adit (763
gpm) was recorded in June 1993; low flow from the Reynolds Adit (6 gpm) was recorded
in April 1994.
Loading: Based on copper as the indicator, Stream C is ranked as the highest peak flow
carrier of metals. 198,221 pounds of copper dissolved in solution were transported by
drainage from July 1993 through June 1994. Peak flow of AMD from the underground
workings in June 1994 was 14% less than flow in June 1993. Copper load from
underground workings in June 1994 was approximately 23% less than the load in June
1993 (Table 4). In July 1994 volume from the underground workings was 25% less than
in July 1993. Copper load from underground workings hi July 1994 was 15% less than in
July 1993. .
Stream D - Summitville Dam Impoundment and Beaver Mud Dump drainage
General: Comprised of the surface drainage into the tailings pond and surrounding area,
and the ground water migration through the mud dump. Possible ground water migration
through tailings contained in the pond. Includes precipitation (snowmelt and rainfall)
infiltrating through BMD materials. Volume and makeup of this stream is expected to
materially change with planned solid waste relocation hi 1994-95 (Cropsy Phase n
operations).
Volume: High flow (202 gpm) was recorded in May 1993; low flow (33 gpm) was
recorded in November 1993. Monitoring was not possible from January 1994 through
April 1994, due to snowpack.
Loading: Based on copper as the indicator, Stream D is ranked as the third highest peak
flow carrier of metals. 12,294 Ibs. of copper dissolved in solution were transported by
drainage from July 1993 through June 1994.
20
-------
Stream E - North Pit Waste Dump drainage
General: Comprised primarily of surface runoff from waste dump materials. There is
some ground water seepage.
Volume: Significantly varies with precipitation (rainfall and snowmelt). Affected by
spring runoff. High flow (284 gpm) was recorded in May 1993; low flow (1 gpm) was
recorded in October 1993. Monitoring was not possible from November 1993 through
April 1994, due to snowpack.
Loading: Based on copper as the indicator, Stream E is ranked as the 6th highest peak
flow carrier of metals. 4,321 Ibs. of copper dissolved in solution were transported by
drainage from July 1993 through June 1994.
Stream F - Clay Ore Stockpile Drainage
General: Comprised of surface drainage migration through lower portions of the waste
dump and precipitation (snowmelt and rainfall) infiltrating through upper level materials.
Water migrating from beneath the CWP may also contribute.
Volume: High flow (66 gpm) was recorded in June 1993; low flow (37 gpm) was
recorded in May 1994.
Loading: Based on copper as the indicator, Stream F is ranked as the 8th highest peak
flow carrier of metals. 1,113 Ibs. of copper dissolved in solution were transported by
drainage from July 1993 through June 1994.
Stream G - Sediment pond P-4 drainage.
General: Comprised of surface drainage from upgradient disturbed areas. Includes some
contribution from Iowa adit drainage.
Volume: Highly variable, dependent on precipitation events. High flow ( 948 gpm) was
recorded in May 1994; low flow (4 gpm) was recorded in November 1993.
Loading: Based on copper as the indicator, Stream G is ranked as the 5th highest peak
flow carrier of metals. 4,508 Ibs. of copper dissolved in solution were transported by
drainage from July 1993 through June 1994.
Stream H - Drainage from Cropsy Creek
General: Comprised of surface drainage from upgradient undisturbed areas. Rerouted
around the CWP and HLP areas during SCMCI operations. Receives some metals
21
-------
loading from surface runoff from the Cropsy Waste Pile and seep LPD-2, downgradient
from the HLP and Dike 1. May receive loadings from effected ground water. Route does
not go through sediment control features.
Volume: Peak flow is concurrent with spring runoff. Significantly affected by
precipitation (snowmelt and rainfall). High flow was recorded in May 1993; low flow
was recorded in February 1994.
Loading: Based on copper as the indicator, Stream H is ranked as the 7th highest peak
flow carrier of metals. 1,737 Ibs. of copper dissolved in solution were transported by
drainage from July 1993 through June 1994.
The affected stream segments are summarized in the following table. The streams are ranked in
decreasing order according to the metal load during peak flow.
Ranking of Surface Water Streams at Peak Flow
without Operation of CWTP, CDP and MRP
Metal Load at
Peak Flow*
1
2
3
4
5
6
7.
8
Stream**
Stream C- Underground Workings Drainage
Stream B- CWP Drainage
Stream D- SDI/BMD Drainage
Stream A- VCD
Stream G- P-4 Drainage
Stream E- NPWD Drainage
Stream H- Cropsy Creek Drainage
Stream F- Clay Ore Stockpile Drainage
* Rankings are listed in decreasing order.
»* Table does not include die HLP wastewater stream.
22
-------
French Drain Sump Inflows
The FD Sump was originally constructed to prevent drainage from the Valley Center Drain
(Stream A) from entering the Cropsy Creek and Wightman Fork. A collection and pumping
facility was installed after VCD drainage was found to contain cyanide. The sump was also
utilized to contain other contaminated water. These drainages (described below) were found to be
contaminated in later years. Tables 1 - 3b summarise data for copper, cyanide, and water volume
for these streams. General descriptions follow.
FDSump-1 Seepage from Dike 1
General: Comprised of water exiting a point at the base of Dike 1.
Volume: Peak volume (1,785,600 gal., June 1993) is concurrent with spring snowmelt
Loading: At peak flow, Stream FD Sump-1 transports up to 83 Ibs of copper per day.
Load declines to less than 3 Ibs per day as flow decreases.
FD Sump -2 Seepage from the Dike 1 ramp
General: Comprised of water exiting a point on the access road that flanks Dike 1.
Volume: Peak volume (820,000 gal. in June 1993) is concurrent with spring snowmelt
Flow ceases soon after the peak snowmelt period. Water is acidic, and contains cyanide.
Loading: At peak flow, Stream FD Sump-2 transports up to 5.7 Ibs of copper per day.
Load declines to less than 1 Ib. per day as flow decreases..
FDSump-3 Drainage from beneath the HLP
General: Comprised of water exiting rock drains built to divert water during HLP
construction at 11,510 and 11,530 elevations. Discharges are combined and routed to the
FD Sump. There is a wide range in copper content Contains a slight amount (0.12 mg/1)
of cyanide at peak volume discharge.
Volume: Peak volume (1,116,000 gal. in June, 1993) is concurrent with spring
snowmelt Significant flow continues throughout the year.
Loading: At peak flow, Stream FD Sump-3 transports up to 27 Ibs of copper per day.
Load declines to less than l Ib. per day as flow decreases.
23
-------
1.5.2 Contaminant Transport and Migration
1.5.2.1 Surface Water
Surface water is considered the most significant media for off-site transport of metals. Surface
water has been impacted by mining operations from the Site throughout the reach of Wightman
Fork, from the Site to the Alamosa River, and within the Alamosa River from Wightman Fork to
Terrace Reservoir and points further downstream. According to the Conceptual Sitewide
Remediation Plan prepared for the EPA, it has been determined that the Site is the predominant
source of metals loading to the Alamosa River system.
As pH of water rises from the addition of water with higher pH, iron precipitates from solution as
a hydrated iron (TO) oxide product (ferric hydroxide). This forms the red or yellow staining seen
on rocks in the streams or on banks. Copper, Cadmium and zinc will co-precipitate with iron
precipitates. Metals concentrations are further reduced by dilution from downstream tributaries.
COPC could be biologically transported through an aquatic food chain, and could be transported
to birds, animals and humans. The Baseline Risk Assessment (BRA) has not been completed;
however, qualitative risk analysis has been performed by EPA which verifies this data (ERT,
1993). The BRA is scheduled for completion in 1995. Currently, the full range of COPC's is
being reassessed and additional contaminants of concern (COC) may be identified in the BRA.
1.5.2.2 Ground'water
Ground water depths vary at the Site. In general, water levels are relatively close to the surface
except in the vicinity of the old mine workings where depth to water can be as much as 300 feet
The old workings act as effective underdrains. This can be seen by the flow of water from the
adits. It is anticipated that the ground water level will rise as water backs up behind the plugged
Reynolds and Chandler Adits.
The ground water occurs in surficial deposits consisting of colluvium, alluvium, and/or glacial
moraine; and fractured andesite of the Summitville Formation. Ground water flow is within the
weathered and fractured bedrock and, within alluvium near the Cropsy Creek and Wightman
Fork channels. Ground water flow and metals are capable of being transmitted to Wightman
Fork through the alluvial and bedrock systems. Ground water is generally shallow (02 to 25 feet
within the alluvium) and flows northeast in both the Cropsy and Wightman Fork drainages.
Shallow ground water at the Site is present as a series of intermittent, perched systems. The
perched aquifer system contributes to recharge of the shallow fractured bedrock system. No
regional ground water table has been identified at the Site. The ground water close to the surface
is strongly influenced by precipitation. During spring runoff, these shallow systems discharge to
24
-------
surface water. Numerous springs and seeps are evident throughout the Site and most flow in
direct response to precipitation.
1.5.2.3 Soil and Air
Site cover consists of topsoil, silt, clays, and gravel. The topsoil is described as
grey/brown/orange, non-plastic with a trace of roots and sand. The clays are low to medium
plasticity with some gravel. The gravel is indicative of colluvial deposits or tailings. The
disruption of the surface soils may be a secondary source of excess metals migration.
1.5.3 Heap Leach Pad
The HLP is approximately 73 acres in size and 200 feet deep at its lowest point (Figure 3). The
HLP consists of 6,700,000 cubic yards of ore containing high levels of metallic sulfides within a
reservoir of cyanide and heavy metals contaminated water. Approximately 100 million gallons
of leachate remains in this reservoir. The Cropsy Creek was diverted around the HLP area and
the HLP was then constructed in the former Cropsy Creek drainage bed. The HLP was originally
constructed with an underliner system consisting of approximately 6 liners. The HLP is
underlain by a French Drain system and extends onto the toe of the CWP which is located
upgradient within the Cropsy Creek drainage bed. The HLP liners have been leaking, causing
water within the French Drain to become contaminated with cyanide and metals.
1.5.4 ARARs
ARARs are "applicable" or "relevant and appropriate" requirements of federal or state law which
address a hazardous substance, pollutant, contaminant, remedial action, location or other
circumstance found at a CERCLA Site. Refer to Table 7 for a detailed summary and discussion
of ARARs. The NCP defines "applicable" requirements as cleanup standards, standards of
control, and other substantive environmental protection requirements, criteria, or limitations
promulgated under Federal or State law that specifically address a hazardous substance,
pollutant, contaminant, remedial action location or other circumstance found at a CERCLA site.
"Relevant and appropriate" requirements address problems or situations sufficiently similar to
those encountered at the CERCLA site that their use is well suited to the environmental or
technical factors at a particular site. (See 40 CFR Section 300.5.)
ARARs are grouped into three categories:
• Chemical Specific
* Action Specific
• Location Specific
25
-------
Chemical specific ARARs include health or risk based narrative standards, numerical values, or
methodologies that, when applied to site-specific conditions establish the acceptable amount or
concentration of a chemical that may remain or can be released to the environment Action
specific ARARs are usually technology or activity-based requirements or limitations on actions
taken with respect to hazardous substances found at CERCLA sites. Location specific ARARs
are restrictions placed on the concentration of hazardous substances or the conduct of activities
solely because they occur in special locations. Examples of special locations include floodplains,
wetlands, historic places and sensitive ecosystems or habitats. (See "CERCLA Compliance with
Other Laws Manual Draft Guidance," EPA/540/G-89/006 August 1988.)
In addition, the NCP has identified a fourth category of information "to be considered" when
evaluating remedial alternatives, known as TBCs. TBCs represent Federal and State advisories,
criteria or guidance that are not ARARs, but are useful in developing CERCLA remedies. (See
40CFR300.430(g)(3).)
The analysis of ARARs has been limited to the scope of the interim action. The NCP allows
waiver of ARARs for interim remedial measures that do not exacerbate site problems or interfere
with final remedy (40 CFR 300.430(f)(l)(iiXC)(l) and 55 FR 8747). Other ARARs may be
involved in enacting final remedy(ies).
In response to comments submitted during the public participation process on the HLP FFS and
Proposed Plan, EPA is further defining the portions of applicable or relevant and appropriate
requirements from Federal and State laws or regulations which must be met by any alternative
implemented as the HLP interim remedial action. Since the ARARs for the HLP were identified
in the "ARARs Addendum to the HLP Focused Feasibility Study Report", this further refinement
of ARARs presents only a minor change to the HLP FFS and Proposed Plan. Consistent with its
"Interim Final Guidance on Preparing Superfund Decision Documents", OSWER Directive
9355.3-02 (June 1989), EPA has determined that this minor change will have little or no impact
on the overall scope, performance, or cost of each alternative as originally presented in the HLP
FFS or Proposed Plan.
The following relevant portions of the HLP ARARs must be met in accordance with Section
121(e) of CERCLA and 40 C.FJL 300.430 of the NCP by each potential HLP interim remedial
action alternative:
7.5.47 Chemical Specific ARARs
Surface Water ARARs
The Colorado Water Quality Standards (CWQS) establish a system for classifying state surface
waters and procedures and criteria for assigning numeric water quality standards. (See 5 CCR
1002-8, Sections 3.1.0 through 3.1.17.)
26
-------
o Colorado Water Quality Standards, Applicable
Criteria for Stream Classification
The CWQS require that surface waters be:
classified for the present beneficial uses of the water, or the beneficial uses that
may be reasonably expected in the future for which the water is suitable in its
present condition or the beneficial uses for which it is to become suitable as a
goal.... Where the use classification is based upon a future use for which the
waters are to become suitable, the numeric standards assigned to such waters to
protect the use classification may require a temporary modification to the
underlying numeric standard... (See §3.1.6.)
The CWQS employ four broad types of beneficial use to frame the classification process:
• recreational
• .aquatic life
• agriculture
+ domestic water supply
Recreational Use
The recreational uses are divided into two classifications. Recreational Use, Class 1 - Primary
Contact, addresses surface water quality concerns where ingestion of small quantities of water
during the use is likely to occur. Recreational Use, Class 2 - Secondary Contact, focuses on
streamside activities where ingestion of water is unlikely to occur. The effect of the recreation
classification on numeric water quality criteria is limited, the primary consideration being the
concentration of fecal colifonn bacteria. The Summirville Minesite is unlikely to contribute
bacterial contamination to the watershed. For that reason, the recreational use classifications will
not be considered further.
Aquatic Life
Two aquatic life classifications are currently promulgated for stream segments of interest Class
1 cold water aquatic life is defined as:
...waters that (1) currently are capable of sustaining a wide variety of cold water biota,
including sensitive species, or (2) could sustain such biota but for correctable water
quality conditions. Waters shall be considered capable of sustaining such biota where
physical habitat, water flows or levels, and water quality conditions result in no
substantial impairment of the abundance and diversity of species. (See §3.1.13(l)(c)(i).)
27
-------
Class 2 cold and warm water aquatic life is defined as:
...waters that are not capable of sustaining a wide variety of cold or warm water biota,
including sensitive species, due to physical habitat, water flows or levels, or uncorretable
water quality conditions that result in substantial impairment of the abundance and
diversity of species. (See §3.1.13(l)(c)(iii).)
Domestic Water Supply
Domestic water supply is defined as:
...suitable or intended to become suitable for potable water supplies. After receiving
standard treatment... these waters will meet Colorado drinking water regulations... (See
§3.1.13(l)(d), emphasis added.)
Agricultural Use
Agricultural use is defined as:
...suitable or intended to become suitable for irrigation of crops usually grown in
Colorado and which are not hazardous as drinking water for livestock... (See
Three segments of the Alamosa River are classified for various uses according to this system:
Segment 6, the Wightman Fork at and below the mine; Segment 3b, the Alamosa River from
immediately above the confluence with Wightman Fork to Terrace Reservoir; and Segment 8,
Terrace Reservoir. Figure 5 shows segments of the Alamosa River Basin.
Segment 6 is classified for Recreation Class 2 and Agriculture. It is not classified for aquatic
life. No numeric water quality standards have been assigned. The lack of an aquatic life
classification was based on testimony received at the Colorado Water Quality Control
Commission (WQCC) hearing. The WQCC determined that an aquatic life classification cannot
be attained within 20 years.
Segment 3b is classified as Class 1 Cold Water Aquatic Life. Numeric Standards are set for
surface water downstream of the confluence of Wightman Fork and the Alamosa River.
Terrace Reservoir is classified as Class 2 Cold Water Aquatic Life. This classification
recognizes a limit on the ability of Terrace Reservoir to sustain a diverse aquatic community.
28
-------
Numeric Water Quality Standards
The CWQS provides a three-tiered structure for establishing numeric water quality standards.
For unimpacted high quality waters, numeric levels known as the "Table Value Standards"
(TVS) are established and presumed to be protective. For impacted waters where pollutant
concentrations exceed TVS values but the beneficial uses are adequately protected. Ambient
Quality-Based Standards can be adopted. For impacted waters where beneficial uses are not
currently adequately protected, TVS are adopted as a goal. Temporary modifications to numeric
standards may be adopted in these areas. Where classified uses are not being protected and a use
attainability analysis has found nonattainability, Site-Specific-Criteria-Based Standards can be
developed. The TVS and Ambient Quality-Based Standards are applicable regulations for
determining compliance with surface water discharges at the Site. Segment 3b of the Alamosa
River is downstream of the Site at the confluence of the Wightman Fork and the Alamosa River.
These regulations were used to establish promulgated standards in this segment of the Alamosa
River. Specifically, the Classifications and Numeric Standards for Rio Grande Basin are found
in Section 3.6.6. of the regulation. Table 8 illustrates these levels. These standards are
categorized into acute and chronic limits. Acute limits represent an upper level not to be
exceeded in any 24 hour period. Chronic standards are average levels which can not be exceeded
hi a 30 day period.
Table Value Standards
The TVS are based upon the Federal Water Quality Criteria. The TVS, however, have been
adjusted to protect the beneficial uses of Colorado waters (See§3.1.7(b)(i)). The TVS for
aluminum (acute), arsenic (acute), lead (acute/chronic), nickel (acute/chronic), selenium
(acute/chronic), silver (acute/chronic), zinc (acute/chronic), chromium VI (acute/chronic),
chromium m (acute), mercury (chronic), manganese (chronic), cadmium (acute/chronic), pH,
dissolved oxygen, Fecal Coli, ammonia, chlorine, sulfide, boron, nitrate and cyanide are set at
Segment 3b. It is important to note that many of the TVS for protection of aquatic life from
metal pollutants are hardness dependent The WQCC has adopted an acute and a chronic copper
standard for Segment 3b. The acute copper standard for Segment 3b is established using the
TVS; however, the WQCC has adopted a less stringent temporary modification to this standard
based upon WQCC hearing testimony. The EPA has adopted and will meet the ambient quality
based chronic copper standard as applicable for this interim action and is not using the less
stringent acute copper standards from the TVS or the less stringent August 1994 temporary
modification. The interim action levels (lALs), as monitored at WF-5.5, were developed to meet
the more stringent ambient quality-based chronic copper standard at Segment 3b.
Ambient Quality-based Standards
Ambient quality-based numeric surface water quality standards are the mechanism where limited
water quality impacts are controlled through less stringent water quality standards. Ambient
quality-based standards are specifically intended to address circumstances where natural or
irreversible man-induced ambient water quality levels are higher than the specific numeric levels
29
-------
contained in the TVS Tables I, n, and HI, but are determined "adequate to protect classified
uses." (See §3.1.7(l)(b)(ii).) The chronic standard for copper is established at Segment 3b using
this regulation. Copper is one of the primary contaminants of concern for water quality. The
chronic copper standard was used as the most strict ARAR for copper at the Site. The lALs were,
developed using this standard. The chronic standard for iron also fells into ambient water quality
standards. There are no acute iron standards.
To evaluate the ability of alternatives to meet the stream classification and numerical standard of
the CWQS ARARs, EPA established lALs for water quality. These IAL can be found at page 23
of the Water Treatment FFS. The IAL are developed using a model which utilized high flow and
low flow average concentrations of the contaminants to set threshold loadings allowable at
Wightman Fork monitoring point 5.5. Numerical standards that would enable the river water
quality to meet the water quality ARAR at Segment 3b under average conditions were then
calculated. Based upon the WQCC numeric water quality standards for Segment 3b, the TVS
levels were used for all COPC at the Site with the exception of copper and iron. EPA used the
WQCC ambient quality standard for copper and iron The ambient level for copper is 30 ug/1
based upon the 85th percentile ambient data in Segment 3a. The methodology used to develop
these levels is similar to the criteria applied in the development of the numeric criteria levels
(NCL), that is, back modeling the contaminant loading from the promulgated ARARs at the
Alamosa River. These IAL are formally adopted as remedial goals in the IRODs.
The discharge monitoring point, WF-5.5, is the interim monitoring point for the Site, and the
IAL are the interim water quality standards during this remedial action five year period. It is
important to note that the lALs are not "interim" due to their inability meet ARARs; rather, EPA
believes that these ARAR-derived limits at the point of compliance do attain the numerical
standards at Segment 3b. The ability of the IAL to achieve the applicable water quality
standards, however, will be reassessed by EPA upon the completion of the quantified Risk
Assessment and the State of Colorado use-attainability study. The results of these efforts will be
incorporated into a final remedy.
o Federal Water Quality Criteria, Applicable
The preamble to the proposed NCP states:
(a) Stale numerical WQS is essentially a site-specific adaptation of a Federal
Water Quality Criteria (FWQQ, subject to EPA approval, and, when available, is
generally the appropriate standard for the specific body of water." (See 53 FR
51442, right column, top.)
As noted above, the FWQC would only be applicable in the absence of current, segment specific
CWQS. In this circumstance, current, segment specific CWQS are available and will be applied
as the surface water quality ARARs for the Site. The FWQC are considered applicable since this
ARAR establishes the basis for the State of Colorado's numerical standards.
30
-------
Ground Water ARARs
The Colorado Ground Water Standards (CGWSs) provide for identification of specified ground
water areas, classification of the specified areas, and numeric ground water quality standards.
5 CCR 1002-8 establishes a system for classifying ground water and adjusting water quality
standards to protect existing and potential beneficial uses. The ground water classifications are
applied to "specified areas," a concept identified in the definitions and explained in Section
3.1 1.4{C)(1). Those ground waters not classified as within "specified areas" may be subject to
Statewide radioactive material standards listed in Section 3.1 1.5(C)(2) of the Basic Standards of
Ground Water, 3.1 1:0 (5 CCR 1002-8) and organic standards identified in Table A of Section
Since the Colorado Water Quality Commission has yet to classify the Site as a "specified area,"
there are no currently applicable or relevant and appropriate Colorado Ground Water numeric
standards for the Site. However, since the publication of the WTFFS, the Colorado Water
Quality Control Commission has adopted an interim narrative standard for all unclassified
ground waters of the State that supplements the Statewide standards for radioactive materials and
organic pollutants established in Section 3.1 1.5(C) of the Basic Standards for Ground Water.
This narrative standard requires that ground water quality be maintained for each parameter at
whichever of the following levels is less restrictive:
(i) existing ambient water quality as of January 31, 1994, or
(ii) that quality which meets the most stringent criteria set forth in Tables 1
through 4 of "The Basic Standards for Ground Water."
Ambient water quality is established by agencies "with authority to implement this standard"
using "their best professional judgment as to what constitutes adequate information to determine
or estimate existing ambient quality, taking into account the location, sampling date, and quality
of all data available" prior to January 31, 1994. Based on Rule 1, Section 1.1(5) of the Mineral
Rules and Regulations, EPA believes the Mined Land Reclamation Board (MLRB) is the agency
that has the primary authority to implement the narrative standard for ground water at the
Summitville Site. MLRB and WQCD established NCLs for surface and ground water quality at
the Summitville Site in SCMCI's operating permit, as well as its 1991 Settlement Agreement
between SCMCI and the State of Colorado. These NCLs are not applicable or relevant and
appropriate, since they are not legally binding, promulgated regulations. However, these
standards have been considered by EPA in establishing its interim action levels for water quality
because they provide useful information or recommended procedures in addressing the
interconnected ground water and surface water at the Site.
31
-------
This interim ground water narrative standard, since it became effective on August 30,1994, was
not identified as an ARAR in any of the FFSs for the Site. However, since compliance with this
ground water ARAR will have little or no impact on the overall scope, performance or cost of the
alternatives evaluated, inclusion of this ARAR represents only a minor change to the FFS and
Proposed Plan. See "Interim Final Guidance on Preparing Superfund Decision Documents,"
OSWER Directive 9355.3-02 (June 1989), at p. 5-3.
EPA further expects that once the CWQC completes its use attainability study and classifies Site
ground water, the interim narrative ground water standard will be replaced by a "specified area"
classification or "site-specific" standard for the Site. This ground water ARAR will be attaint
by the final remedial action(s) for the Site.
Storm Water Management and Effluent Limitations ARARs
Storm water management is governed by the storm water permitting requirements and the
Categorical Standards for Ore Mining and Dressing. Both the storm water permitting program
and the categorical standards are as applied pursuant to the Colorado Discharge Permit System.
Requirements are collection and treatment of storm waters using the Best Available Technology
(BAT) for those storm waters which contact mine waste. In addition, both regulatory programs
require implementation of Site-specific Best Management Practices (BMP). The BMP
emphasize storm water diversion and land/soil reclamation to minimize the contact of storm
water with mine wastes.
o Copper, Lead, Zinc, Gold, Silver and Molybdenum Ores Subcategory Effluent
Limitations, Relevant and Appropriate
This ARAR applies to "process waste waters" only. Process waters are defined hi 40 CFR
401.11(q)as:
"any waters which, during manufacturing or processing, comes into direct contact
with or results from the production of any raw material, intermediate product,
finished product, by-product, or waste product"
The effluent limitations found in 40 CFR 440.103 would be appropriate and relevant to the
Water Treatment FFS activities but not applicable because the discharges are not "process waste
waters." The IAL established by EPA to meet the surface water quality ARARs are more
stringent than these categorical effluent limitations.
o Colorado Discharge Permit System Regulations/Federal Storm Water Permitting
Requirements
Colorado's authority to require permits for the discharge of pollutants from any point source into
waters of the state are derived from the Federal National Pollutant Discharge Elimination System
32
-------
(NPDES) regulations. See 40 CFR Part 122. Colorado's NPDES based program can be found in
the Colorado Discharge Permit System Regulations (CDPSR). The CWQCC Division Permit
issued for the treatment plant at the Site (CDP #CO-0041947), dated November 12; 1991, is the
CDPSR document for the Site. Additional permit modification activities are documented in the
July 1991 Settlement Agreement and the July 1992 Amendment to the Settlement Agreement
Storm water is defined in NPDES program as "storm water runoff, surface runoff, snow melt
runoff, and surface runoff and drainage." (See 40 CFR 12226(b)(13).) A permit application is
required for active and inactive mining sites where an owner can be identified and when
discharges of storm water runoff from mining operations come into contact with any overburden,
raw material, intermediate product, finished product, by product, waste product or areas where
tailing have been removed. (See 12226(b)(14)(iii).) As such, the substantive NPDES Storm
Water permit requirements are applicable to discemable surface flows of storm water that
contacts waste rock, the crushed ore currently contained in the heap leach pads, wet waste rock
(mud), clay ore, or tailings at the Summitville Minesite. Infiltration is not covered by this
program. (See 55 FR 47996, left column, center.)
The storm water permit regulations require compliance with Sections 301 and 402 of the Clean
Water Act Sections 301 and 402 require use of Best Available Technology to control toxic
pollutants, and where necessary, further control to achieve ambient water quality criteria. In
addition, the storm water regulations require implementation of stormwater BMP as part of the
comprehensive program.
EPA has established effluent limitation guidelines for storm water discharges from the Ore
Mining and Dressing category. These effluent limits require application of BAT to the Ore
Mining and Dressing category. In those regulations, EPA has defined "mine" broadly and a hi
manner which coincides with the definition provided in the Storm Water Permit requirements.
(See 40 CFR 440.132(g).) The effluent limitation guidelines for Ore Mining and Dressing also
provide an exemption for overflow of excess storm water caused by a greater than a 10 year 24
hour precipitation event when a facility has met certain design and operational prerequisites.
This exemption remains in effect as part of the new independent storm water permitting program.
(See 55 FR 48032, right column, bottom.) .
Both the effluent limits and the storm water permitting program require application of BAT and,
if necessary, additional controls to meet ambient water quality standards. In addition, both
programs require implementation of stormwater BMP. The only jurisdictional distinction is that
the Ore Mining and Dressing Category effluent limite are not applicable, but instead relevant and
appropriate. The recognition by the storm water permit program of the overflow exemption
demonstrates the existing equivalence of the programs. Thus, attainment of the Effluent
Guidelines and Standards for Ore Mining and Dressing will ensure attainment of the storm water
discharge requirements.
33
-------
Eight outfalls were identified at the Summitville Minesite which meet the point source discharge
requirement for storm water permitting. The discharge from each of these outfalls have been
attributed to one of the three categories of precipitation related discharges defined by the storm
water regulations. (See 40 C.F.R. 122 J6(b)(l3); 55 Federal Register at 48065.
Pursuant to the NPDES Storm Water Permitting requirements and hi response to obligations
under the July 1,1991 Settlement Agreement and Compliance Plan (the Compliance Plan) for
Summitville Mine, a two volume Best Management Practices (BMP) plan dated October 31,
1991 was developed. The Compliance Plan required that the BMP provide a reclamation plan
and implementation schedule that included existing and planned pollution prevention practices.
The BMP also evaluated the need for long term treatment of storm water drainage at the facility.
The BMP was designed to minimi?*; or control contact between precipitation and potential
sources of pollutants. The BMP developed at the Summitville Minesite included housekeeping,
employee training, inspections, preventative maintenance. In addition, reclamation activities
such as grading, stabilization, revegetation, erosion control and sediment control were included
as part of the BMP. Each of the measures was designed to protect the existing water quality and
quantity during the operation phase and upon closure of the Summitville Mine.
The existing BMP plan which is currently being implemented at the Site and will continue to be
implemented regardless of which alternative is selected, attains compliance with the NPDES
stormwater and categorical point source standards.
1.5.4.2 Action Specific ARARs
RCRA Subtitle C
40 CFR 261.4(b)(7) specifically excludes "solid waste from the extraction, benification and
processing of ores and minerals..." from the rules governing management of hazardous waste in
RCRA Subtitle C. Mine wastes present at the Summitville Minesite, including waste rock, the
crushed ore currently contained in the heap leach pads, wet waste rock (mud), clay ore, and
tailings, were generated as a result of the extraction, processing or benification of ores and
minerals. Accordingly, RCRA Subtitle C is not applicable to the remediation of this mine waste.
RCRA Subtitle C may be relevant and appropriate to actions at the Summitville Minesite if the
mine waste materials are sufficiently similar to RCRA hazardous waste, particularly if the
subject wastes fail the Toxicity Characteristics Leachibility Procedure (TCLP) or exhibit other
characteristics of RCRA hazardous wastes (i.e, low pH). See, "Superfund Guide to RCRA
Management Requirements for Mineral Processing Wastes, 2nd Edition," OERR Directive
9347.3a-12 (August 1991).
34
-------
Further, if the disposal activity involves the use of a waste management unit sufficiently similar
to a RCRA regulated unit, and the unit is to receive wastes sufficiently similar to RCRA
hazardous wastes, the RCRA Subtitle C requirements pertaining to that type of waste
management unit would be relevant and appropriate. (See 55 FR 87630.)
The EPA has stated, when describing its overall liquids management strategy for RCRA Subtitle
C land disposal units:
as described in the preamble to the minimum technology regulations (47 FR
32274, July 26,1982 and 51 FR 10706, March 28,1986), the Agency's general
strategy for such units is to impose design and operation requirements to
minimise leachate generation (i.e., caps and prohibition on liquids in landfills)
and then to require removal of the leachate before liquids migrate into the
environment (See 52 FR 8712.)
Given the. acid and contaminated leachate generating potential of the materials found at the
CWP, BMD, SDI and Mine Pits portions of the Site, EPA determined that the wastes are
sufficiently similar to hazardous wastes to warrant imposition of selected portions of RCRA
Subtitle C requirements. The Subpart L Waste Pile closure requirements, Subpart K Surface
Impoundment closure requirements and Subpart N Landfill closure requirements are therefore
relevant and appropriate to the closure of the CWP, BMD, SDI and Mine Pits. Accordingly,
following placement of the materials hi the Mine Pits, the unit must be closed hi a manner that
attains the following relevant and appropriate requirements:
• provision of a low maintenance cover that minimizes migration of liquids
through the closed unit; promotes effective drainage; minimizes cover
erosion; and is capable of accommodating settling and subsidence (See 40
CFR 264.310(a), 264228(a), 264258(b); and
• provision for long term maintenance of the cover, continued operation of the
leachate collection system and continued control of run-on and run-off (See 40
CFR 264.310(b), 264.228(b), 264258(b).
Colorado Mined Land Reclamation Act
The Colorado Mined Land Reclamation (MLR) regulations at 2 CCR 407-1 require the
reclamation of mined areas. The MLR regulations provide specific reclamation criteria which
are applicable to the Summitville Minesite. In particular, Rule 3 of the Mineral Rules and
Regulations of the Colorado Mined Land Reclamation Board is applicable to the remedial action
being implemented at the CWP. The remedial alternatives must attain the requirements for
reclamation measures and the reclamation performance standards found in §§ 3.1.5 (Reclamation
Measures — Materials Handling), 3.1.9 (Topsoiling), and 3.1.10 (Revegetation). The general
35
-------
water (§3.1.6), ground water (§3.1.7), wildlife (§3.1.8) and building and structures (§3.1.11)
requirements, while also applicable to the CWP interim remedial action, will be met with the
attainment of other federal or state ARARs which provide more stringent standards for the same
subject matters.
The conditions imposed by the Colorado MLR Permit #M-84-157 for the Summitville Mine
stipulated a phased approach to land reclamation which minimizes the total disturbed area at any
point in time. When mining activities in each area have been completed and the sections no
longer needed, the permit requires that all land associated with waste dumps, leach heaps, roads,
mine pits and plant facilities be reclaimed for forage and timber use. Reclamation activities at
the Summitville Minesite will emphasize surface soil stabilization (to include grading, top soil
management, and revegetation), preservation of water quantity and quality, and concern for the
safety and protection of wildlife.
The reclamation requirements of the MLR are ARARs, not the site specific MLR reclamation
plan. Regardless, the existing MLR reclamation plan does represent the site specific application
of the MLR, and is, therefore, a to-be considered from an ARAR perspective.
Clean Air Act
Federal and state ARARs were identified for construction and generation of particulate matter
(PM10) at the Site. An emission permit will be required if temporary construction activities
exceed two years. (See 5.CCR 1001, §3(I)(B)(3)(e).) Control measures to minimise dust and air
monitoring will be implemented if necessary during remedial construction activities. Regulation
1 of the Colorado Air Pollution Control Regulations requires all sources of particulate emissions
to utilize technically feasible and economically reasonable control measures. This requirement is
applicable to remedial activities that produce fugitive particulate emissions at the Site.
An air pollution permit was applied for at Summitville Minesite for the emission of hydrogen
cyanide as a stationary source. The permit included a description of the cyanide heap leach pad
process at the Summitville Mine and all associated process chemistry. Permit # 92-RG-653 was
given an exempt status in September 1992. The Summitville Site claimed uncontrolled
emissions of less thqn one ton per year and no emissions of hazardous, odorous or toxic
pollutants and was, therefore, exempt (See 5 CCR Section 3(n)(C)(l)(j).) Thus, this particular
requirement is not applicable or relevant and appropriate at the Site.
1.5.4.3 Location Specific ARARs
National Historical Preservation Act
The National Historic Preservation Act (NHPA) requires federal agencies to account for the
effects any federally assisted undertaking on districts, sites, buildings, structures of objects that
are included on the National Register of Historic Places. Executive Order 11593 also requires .
36
-------
consideration of the cultural environment. Similarly, the Colorado Register of Historic Places
establishes requirements for protection of properties of state historical interest In addition, the
Historic and Archeological Data Preservation Act of 1974 establishes procedures to preserve
historical and archeological data which might be destroyed through alteration of terrain as a
result of federal construction projects.
At the Summitville Minesite, an inventory of historic, cultural and archeological resources will
be performed. This inventory will serve to identify cultural and historic resources that must be
considered during the development, analysis, selection and implementation of a remedy. In
addition, the inventory will identify historic and cultural resources that are candidates for
inclusion on either the state or national historic registers.
Endangered Species
The Endangered Species Act requires that federal agencies ensure that federal actions will not
jeopardize the continued existence of any threatened or endangered species or impact critical
habitat In response, a Preliminary Natural Resource Survey will be performed to identify
natural resources, habitat types, endangered or threatened species, and any potential adverse
effects or injury to trust resources.
Protection ofFloodplains and Wetlands
Executive Order No. 11988 and Executive Order No. 11990 require federal agencies to evaluate
the potential adverse effects of proposed actions on floodplains and wetlands, respectively.
Floodplains and wetlands potentially subject to adverse impacts from site remedial actions will
be inventoried and considered during the analysis, selection and implementation of the remedy.
Clean Water Act — Dredge and Fill Requirements.
Section 404 of the Clean Water Act prohibits the discharge of dredged or fill material into
navigable waters, including wetlands. The Section 404 requirements are applicable if any
remedial action construction will involve dredged and fill activities.
Fish and Wildlife Coordination Act
The Fish and Wildlife Coordination Act serves to protect fish and wildlife when federal actions
result in the control or structural modification to natural streams or water bodies. Federal
agencies must develop measures to prevent, mitigate or compensate for project related losses of
fish and wildlife. Specifically included are projects involving stream relocation and water
diversion structures. If applicable, prior to modification of water bodies, the applicable
regulation will be followed.
37
-------
Colorado Wildlife Act
The act establishes the Colorado Wildlife Commission, provides for wildlife management, and
prohibits actions detrimental to wildlife. The act is applicable if wildlife observed at the Site
would be adversely impacted by the implementation of the remedial action.
Wildlife Commission Regulations
Chapter 10 of the Colorado Wildlife Commission regulations 92 CCR 406-8, Chapter 100
designates and protects certain endangered or threatened species. The regulation are applicable if
endangered or threatened species observed at the Site are adversely impacted by the
implementation of the remedial action.
Floodplain Management
The Executive Order on Floodplain Management (No. 11988) and 40 CFR §6.302(b) and
Appendix A requires federal agencies to evaluate the potential effects of actions they may take in
a floodplain and to avoid, to the maximum extent possible, any adverse impacts associated with
direct and indirect development in a floodplain. This requirement may be applicable if the
remedial activities take place in a floodplain.
Wetlands Protection
Executive Order on Protection of Wetlands (No. 11990) and 40 CFR §6.302(b) and Appendix A
require federal agencies to evaluate the potential effects of actions they may take in wetlands, in
order to minimise adverse impacts to wetlands. This requirement is applicable if the remedial
activities take place in wetlands.
1.6 Summary of Site Risks
The Human Health and Ecological Risk Assessment for the FFS was conducted using relevant
EPA guidance including the Risk Assessment Guidance for Superfund and the Resource
Conservation Recovery Act (RCRA) Facility Investigation (RFI) Guidance. This risk
assessment was a screening level risk assessment intended to briefly examine risks associated
with the HLP.
1.6.1 Screening Ecological Risk Assessment
A Screening Ecological Risk Assessment for the SummitvUle Minesite was prepared by EPA in
April, 1993. The screening ecological risk assessment reviewed the no action alternative to
38
-------
determine if there is an imminent hazard to the Wightman Fork from the site. Copper, zinc, and
cyanide were chosen as the COPC for the assessment
The assessment modelled, measured, and predicted concentrations and loading of copper in
Wightman Fork for three scenarios:
• April 1993 conditions (included treatment of HLP contained water and discharge
from the Reynolds Adit);
• Cessation of water treatment activities; and
• Catastrophic release of water contained in the HLP that could result from an event
such as failure of Dike 1, the downgradient impoundment feature.
Effects of the contaminants on rainbow trout and brook trout were estimated by correlating acute
toxicity levels of the contaminants with measured and predicted concentrations. The degree of
metals toxicity for aquatic life as affected by the pH and hardness of water was described. Study
results of copper concentrations that are toxic to trout at differing water hardnesses were included
in the assessment to illustrate the variation of toxic copper concentrations with water hardness
(the sum of calcium and magnesium concentration expressed in terms of equivalent calcium
carbonate).
The screening ecological risk assessment recommended the following:
• Continuation of Site water treatment prior to discharge and decrease of loading of
metals into the stream to State of Colorado NPDES permit levels;
• Reduction of the flow of contaminated ground water through plugging the adits
for long-term metal loading reductions to the Wightman Fork;
• Conducting an ecological survey of Wightman Fork to obtain Site specific
information to document actual discharge impacts and document recovery of
Wightman Fork after remediation; and
• Completion of a baseline risk assessment because the review of the no action
alternative produced an unacceptable risk, defined as exceeding the Low
Observed Adverse Effect Level (LOAEL).
The screening ecological risk assessment predicts an imminent hazard to the environment and
suggests that all appropriate response actions should be undertaken to prevent the adverse effects
from continuing to take place. The HLP interim action is intended to stabilize a portion of the
Site, prevent further environmental degradation, and achieve significant risk reduction. The HLP
39
-------
interim remedial action will be combined with other actions to address additional sources of
contamination.
1.6.2 Environmental Risk Assessment
1.6.2.1 Aquatic Receptors
In general, the potential risks to aquatic organisms posed by an untreated release from the French
Drain are predicted to be immediate and pronounced Chemicals of potential concern in the
French Drain exceed acute and chronic surface water goals by several orders of magnitude.
Modelling predicts that concentrations of cyanide discharging from Cropsy Creek regain acutely
toxic until the confluence of the Wightman Fork with the Alamosa River. Furthermore, the
concentrations of cyanide would remain at levels hi excess of the Colorado TVS in the Alamosa
River for some distance below Wightman Fork. The TVS are promulgated, risk based standards
developed to protect aquatic life uses.
It is important to note that the Site's impact on pH alone may contribute to toxicity to aquatic ' .
organisms, as there is a limited range of pH levels tolerated by aquatic receptors.
Prior to treatment of the Chandler Adit, the Colorado TVS, ARARs in Segment 3b of the
Alamosa River, were regularly exceeded for copper, zinc, aluminum, iron and manganese. These
exceedences are especially problematic as the hardness-dependent Colorado TVS may
underestimate the potential toxicity of metals in the acid drainage (low pH) environment below
theHLP. Normally, toxicity is reduced as hardness is increased. However, an underlying
assumption of the criteria is that alkalinity increases as hardness increases. This assumption
holds for many natural waters, however, at the Sumrnitville Minesite hardness is relatively high
and alkalinity is low. Ranges of data collected in 1993 at Station 45.4 from Segment 3b of the
Alamosa River are as follows:
Flow Season Analyte Maximum Mean TVS
May-July Dissolved Copper 2600ug/L 1084ug/L 30ug/L
October-March Dissolved Copper 780u.g/L 780u.g/L 30ug/L
May-July Dissolved Zinc 450yg/L 301jig/L 230ug/L
October-March Dissolved Zinc 437ug/L 437ug/L .230ug/L
The Colorado Division of Wildlife, in comments on the proposed ambient water quality standard
for the Site, found that a self-maintaining population of brook trout was present in the Alamosa
river segment that extends from the confluence of the South Fork of the Alamosa to Sumrnitville
in 1987. The population appears to have been eliminated in the intervening years by
contamination of the Alamosa River. This contamination was caused by Site operations when
waste material was placed in the Alamosa River drainage beginning hi 1988. Since this stream
40
-------
segment supported a self-maintaining brook trout fishery prior to the SCMCI's mining
operations, this contamination could be reversed through reclamation activities.
1.6.2.2 Terrestrial Wildlife
An untreated release from the French Drain would pose significant risks to bird and mammal
populations. Based on the modeled concentrations, risks to terrestrial wildlife firom acute and
chronic exposures to cyanide would be high along Cropsy Creek and Wightman Fork. The
potential for chronic exposure is mitigated by the unsuitable habitats surrounding these sites.
The lack of suitable habitats makes regular use of these areas unlikely
The other COPC that pose potential acute risks to bird and mammal species in Cropsy Creek
include: cadmium, copper, and manganese. Risks from acute exposure in Wightman Fork are
substantially lower, although the risks from chronic exposure in those areas with suitable habitat
(i.e.. natural, undisturbed habitats) may be present
1.6.3 Human Health Risk Assessment
The potential for exposure is based on the existing Site conditions and potential future Site
conditions. Groups assessed for potential exposure pathways include on-site workers, on-site
residents, off-site residents, and intruders/trespassers. Presently, access to the Site is being
controlled. Currently, on-site workers, trained under OSHA HAZWOPER, are required to use
personal protective equipment (PPE), and are routinely monitored; therefore, they are evaluated
under a separate process. Since the Site is a historic mining district, on-site residents are not
considered a viable exposed population currently or in the future. Off-site residents and potential
off-site recreational receptors will require evaluation during a baseline risk assessment
1.6.3.1 Exposure Scenario
The potential for exposure is based on the existing Site conditions and potential future Site
conditions. Groups assessed for potential exposure pathways include on-site workers, on-site
residents, off-site residents, and intruders/trespassers. Presently, access to the Site is being
controlled. Currently, on-site workers, trained under OSHA HAZWOPER, are required to use
personal protective equipment (PPE), and are routinely monitored; therefore, they are evaluated
under a separate process. Since the Site is a historic mining district, on-site residents are not
considered a viable exposed population currently or in the future. Off-site residents and potential
off-site recreational receptors will require evaluation during a baseline risk assessment
41
-------
/. 6.3.2 Exposure Pathways
An exposure pathway describes the route a chemical may take from the source to the exposed
individual. A complete pathway consists of four elements: a source and mechanism of chemical
release to the environment, an environmental transport medium, a point of potential human
contact with contaminated medium, and an exposure route. The transport medium can be air,
ground water, soil, surface water, etc. The route can be inhalation ingestion or dermal contact
with the medium.
Evaluation of the potential pathways suggests that most exposure pathways at the Site are
incomplete. Currently, the only pathway with sufficient data for assessment is surface water.
There is insufficient sampling data available to determine whether soil, ground water, and/or air
are exposure pathways.
1.7 Description of Alternatives
This section describes the alternatives retained for detailed analysis for this interim remedial
action. A description of all options considered for the HLP ROD can be found in the HLP FFS.
The six alternatives retained for detailed analysis to be discussed in this ROD are the following
(see Table 9).
1.7.1 Alternative 5-1: No Action
This alternative assumes no additional action or construction activities will be undertaken at the
current time. This alternative also assumes the existing volume of leachate currently retained in
the saturated zone between the underiiner and the 11,550 foot elevation will be left in place with
no additional treatment The HLP would continue to release cyanide and metals to the
environment Periodic monitoring of ground water would be required to assess the quantities of
cyanide and/or metal contaminants, discharging from the HLP.
1.7.2 Alternative 5-2: Pump and Treat/Recontour & Cap
This alternative involves pumping and treating leachate contained in the saturated zone of the
HLP followed by discharge of treated waters to Wightman Fork. The leachate would be treated
in the existing CDP and the MRP at a flow rate of 700 gpm. Water treatment would consist of
the addition of hydrogen peroxide in the CDP to reduce cyanide concentrations and the use of an
insoluble sulfide precipitation process in the MRP. Up to 6 months will be required to complete
42
-------
the draining of the HLP, during which time all flows entering the French Drain would be
combined with the leachate and treated in the CDP and MRP plants.
New extraction pumps would be lowered into the existing well cans on the north side of the HLP
or new extraction wells with pumps would be drilled and installed adjacent to the well cans.
Either approach would ensure the pump intakes are at the lowest levels within the HLP. The
existing pipelines to and from the CDP and MRP plants would be maintained.
After the draining and treating of the leachate is underway, the HLP would be graded,
recontoured to a 4:1 slope, and capped using a four foot layer of crushed stone covered with six.
inches of topsoil. Recontouring and capping would minimize infiltration and revegetation to
achieve slope stability and adequate diversion of surface water flows around the HLP, and
decrease flows from the HLP itself. Existing surface water diversions both up and downstream
of the HLP would be re-evaluated following the completion of the EE/CA for the CWP, and
reworked, if required. Recontouring and capping is expected to require one construction season
to complete.
The primary goal of this alternative is to minimize water infiltration into the HLP with the cap
and cover, while preventing subsequent acid generation and metal mobilization. Any residual
cyanide contamination adsorbed on the solid surfaces of the ore material would be held in place
within the HLP, as long as the HLP is able to maintain its drained state. Following the draining
and treating of the leachate, both the CDP and MRP plants would be held in standby operation hi
the event precipitation occurrences and/or spring run-offs create leachate within the HLP with
elevated metals concentrations. The HLP would act as its own surge or storage pond, with HLP
solutions being treated when high solution levels and concentrations are encountered. The
underliner within the HLP will remain in tact, and the existing French Drain beneath the HLP
would be maintained to provide direct discharge of all ground water flows.
The standby water treatment, consisting of the potential use of the CDP and MRP plants, would
be maintained for an indefinite period, pending long term monitoring assessments to confirm
changes in the migration of cyanide and/or metal contaminants. The sludge generated from the
water treatment would be placed hi the HLP for mining with the spent ore prior to recontouring.
After the leachate in the HLP is pumped and treated, water treatment would convert to
biotreatment for one full year.
1.7.3 Alternative 5-3: Injection-Extraction Wells/Pump & Treat/Biotreatment/ Recontour &
Cap/Bioreactor
This alternative includes an HLP solution collection system consisting of injection/extraction
wells installed in the HLP hi a grid pattern (i.e. 100-ft. or 200-ft centers) to collect and divert all
HLP infiltration to the existing CDP and MRP plants for treatment The existing pipelines to and
43
-------
from the CDP and MRP plants would be routed and tied into the injection/extraction wells. To
prepare for biotreatment, all leachate would be pumped, treated and discharged off-site.
Water treatment would initially consist of hydrogen peroxide in the CDP and the insoluble
sulfide precipitation process in the MRP. During this treatment period, all flows entering the
French Drain would be combined with the leachate and treated in the CDP and MRP plants. The
sludge generated from the water treatment would be placed in the HLP for mixing with the spent
ore prior to recontouring. After the leachate in the HLP is pumped and treated, water treatment
would convert to biotreatment for one full year.
The objective of the biotreatment process is to destroy the cyanide. Biotreatment micro-
organisms and additives would be introduced into biotreatment tanks incorporated into the water
circulation circuit, while inorganic chemical additions would cease. Eventually, as the
biotreatment process progresses, inoculation of ore solids contained in the HLP would begin.
One pore volume of solution would be used to inoculate the ore. Upon completion of the
cyanide detoxification efforts, the residual solutions in the HLP would be pumped, treated for
metals removal in the MRP, and discharged off-site.
The HLP would be graded, recontoured, capped and revegetated to achieve slope stability and
adequate diversion of surface water flows around the HLP, and to decrease flow from the HLP
itself. Existing surface water diversions both up and downstream of the HLP would be re-
evaluated following the completion of the EE/CA for the CWP, and reworked, if required. This
construction activity is expected to require two construction seasons to complete.
.j
The HLP underliner will remain as is and the existing French Drain beneath the HLP would be
maintained to provide free drainage of all ground water flows.
Upon completing the draining of the residual biotreatment solutions, it is intended that all flows
entering the French Drain will be discharged untreated from the Site. If the flows entering the
French Drain are of poor quality (i.e.. metals concentrations greater than surface water quality
standards), the lined surge pond and corresponding bioreactor using sulfate reducing bacteria .
would be activated. Significant buildup of contaminated leachate in the HLP would be pumped
to the surge pond for controlled rate discharge to the bioreactor. Use of bioreactor would reduce
the need for active water treatment by reducing metal mobilization and detoxifying cyanide and
thereby reducing operating costs. The bioreactor would use a geomembrane cover to exclude
oxygen (as opposed to a natural plant cover used in an artificial wetland). Periodic monitoring of
ground water would be required to assess cyanide and/or metal concentrations.
The duration of bioreactor operation is unknown. The longevity of the bioreactor substrate is
difficult to predict, but should be a minimum of 3 years. Replacement of the substrate will be
required due to reduction of the nutrients needed by the bacteria, buildup of metal sulfide
precipitation, and bed plugging.
44
-------
1.7.4 Alternative 5-4: Extraction Pumps & Undetdrippers/Water Rinse/Recontour & Cap
This alternative includes new extraction pumps into the existing well cans on the north side of
the HLP, or installation of new extraction wells installed adjacent the well cans. A minimum of
4 extraction well pumps are necessary. The existing pipelines to and from the CDP and MRP
plants would be tied into the extraction pumps (the underdripper system is currently tied in). The
leachate in the HLP would not have to be removed initially. Rinsing would be accomplished
using the existing underdripper system and new surface dripper systems. About half of the HLP
ore volume could be rinsed in this manner. Water treatment would consist of hydrogen peroxide
in the CDP and the insoluble sulfide precipitation process in the MRP. Water rinsing of the HLP
would continue for about 18 months.
During this water rinse program, all flows entering the French Drain would be combined with the
rinse cycles and treated in the CDP and MRP plants. Upon completion of the water rinsing
efforts, the residual leachate in the HLP would be pumped, treated and discharged off-site. The
sludge generated from the water treatment during the first two years would be placed in the HLP
for mixing with the spent ore prior to recontouring. Sludge generated after the first two years
would be dewatered and disposed off-site.
The HLP would be graded, recontoured, capped and revegetated to achieve slope stability and
adequate routing of surface water flows around the HLP. These measures would minimise the
flow from the HLP itself. Existing surface water diversions both up- and down-stream of the
HLP, would be re-evaluated following the completion of the EE/CA for the CWP and reworked,
if required. This construction activity is expected to require three construction seasons to
complete.
Upon completing the rinsing, draining and treating of all leachates, both the CDP and MRP
plants would be placed in standby operation. Plant operations would be initiated in the event
precipitation occurrences and/or spring run-off require treatment of solutions accumulating
within the HLP. The HLP underliner will remain as is, and the existing French Drain beneath the
HLP would be maintained to provide free drainage of all ground water flows. Upon completing
the draining of residual solutions in the HLP, all flows entering the French Drain will be
discharged untreated from the Site. Periodic monitoring of ground water would be required to
assess cyanide and/or metal concentrations.
1.7.5 Alternative 5-5: Partial HLP Removal/Injection-Extraction Wells/Water Rinse/Recontour
&Cap
This alternative includes removing the upper portion of the HLP down to the first set of
intermediate liners at the 11,610 ft elevation. The excavated material and liners would be hauled
and backfilled into the Mine Pits which hi turn would be contoured and revegetated. The
45
-------
remainder of the HLP would be opened up by drilling a series of injection/extraction wells in a
grid pattern (i.e 100-ft. or 200-ft. centers) to collect and divert all water infiltrations to the
existing CDP and MRP treatment facilities. The removal of 3 to 6 liners will improve the ability
to flush the remainder of the HLP. In addition, the removed ore could be used as capping
material for the mine pits. The existing pipelines to and from the CDP and MRP plants would be
routed and tied into the injection/extraction wells.
Water treatment would consist of hydrogen peroxide in the CDP and the insoluble sutfide
precipitation process- in the MRP. Water rinsing of the HLP would continue for a full two years
during which time no effort will be made to collect and treat discharges from the French Drain
Sump. The sludge generated from the water treatment during this time would be placed in the
HLP for mixing with the spent ore prior to recontouring. Sludge generated after the first two
years would be dewatered and disposed off-site.
Upon completion of the cyanide detoxification, the residual leachate in the HLP would be treated
and discharged. The lower portion of the HLP would be graded, recontoured, capped and
revegetated to achieve slope stability and adequate routing of surface water flows around and
from the HLP itself. Existing surface water diversions both up- and down-stream of the HLP
would be re-evaluated following the completion of the EE/CA for the CWP and reworked, if
required. This construction activity is expected to require 2 and one-half years to complete. The
underliner within the HLP will remain intact, and the existing french drain beneath the HLP
would be mainlined to provide free drainage of all ground water flows.
With the exception of the two-year water rinse period, all flows entering the French Drain will be
discharged untreated from the Site. Surface and ground water flows entering from upstream
sources would serve as a diluting media for the small amount of discharge still emanating from
the HLP. With subsequent drop in hydraulic head following the discharge of all solutions from
the HLP, very little driving force would be encountered to force residual contaminants from the
HLP. Periodic monitoring of ground water would be required to assess cyanide and/or metal
concentrations.
1.7.6. Alternative 5-6: Pump and Treat/Total HLP Removal/Ex situ Ore Treatment/Disposal
On-Site
This alternative involves remediation of the HLP by excavating and dismantling the entire HLP.
Initially, the leachate contained in the saturated zone of the HLP would be pumped and treated in
the existing CDP and MRP water treatment plants. The flow rate would be 700 gpm, requiring
up to 6 months to complete the draining of the HLP during which time all flows entering the
French Drain would also be combined with the leachate and treated in the CDP and MRP plants.
46
-------
Upon completing the draining of leachate in the HLP, all flows entering the French Drain will be
discharged untreated from the Site. The HLP would be dismantled by conventional earth moving
and mine equipment
The spent ore material would be treated by water rinsing in conventional milling equipment to
remove adsorbed cyanide contaminations. The treated solids would be hauled for disposal into
the Mine Pits. The backfilled material would be graded, contoured, capped and revegetated to
provide positive drainage and minimise air and water infiltration Water washes during milling
would use chemical oxidants and/or biotreatment chemicals to assist in detoxifying cyanide from
the ore solids and oxidize the soluble cyanide. The washes would be caught and recycled to
water usage. Upon full excavation of the HLP, the HLP footprint would be graded,
contoured, amended with neutralising materials and revegetated to prevent further erosion and
acid rock drainage (ARD) generation.
Upon completion of the ore treatment, all water used in the rinsing of the ore would be treated
and discharged. During the execution of this alternative, both the CDP and MRP plants would
be held in standby operation. Plant operations would.be initiated in the event precipitation
occurrences and/or spring run-offs require treatment of waters and solutions accumulating in and
around the HLP. Until the excavation reached the lower sections of the HLP, the underliner
would remain intact, and the existing French Drain beneath the HLP would be maintained to
provide free drainage of all ground water flows. This alternative would require two to three
construction seasons to complete.
1.8 Comparative Analysis of Alternatives
The evaluation criteria are requirements that must be addressed in this IROD. CERCLA requires
that remedial actions must satisfy the following threshold criteria:
• Protect human health and the environment
• Attain ARARs (or provide grounds for invoking an interim action waiver)
After satisfying the threshold criteria, the following balancing criteria are evaluated:
• Long term effectiveness
• Reduction of toxicity, mobility or volume as a principal element
• Short term effectiveness
• Implementability
• Cost effectiveness
• State acceptance
. Community acceptance
47
-------
Each of the alternatives retained after the initial screening is evaluated in this section against
these nine criteria in accordance with the National Oil and Hazardous Substances Contingency
Plan (NCP). Table 10 summarizes the comparative analysis of alternatives.
1.8.1 Criteria 1: Overall Protection of Human Health and the Environment
This criterion assesses the protection provided by each alternative to human health and the
environment Overall protection focuses on the level of protection provided by each alternative
and how Site risks will be eliminated, reduced, or controlled through treatment, engineering or
institutional controls.
Alternative 5-6 would provide the highest protection through removal of the HLP to the mine
pits. Alternative 5-1 would provide the least protection. The remaining alternatives
would provide protection ranging from moderate to high, depending on type and number of
remedial technologies and process options employed. (See Table 10).
The principal environmental impact from the HLP is cyanide and toxic metals being released to
Wightman Fork and the Alamosa River. Alternative 5-6 controls those impacts to Wightman
Fork and the Alamosa River by effectively reducing the amount of contaminated drainage that is
released into these surface water bodies.
Alternatives 5-3,5-4,5-5 provide equivalent protectiveness to Alternative 5-6, but may require
continued water treatment to maintain Risk-Based Action Levels to achieve final remediation
goals.
1.8.2 Criteria 2: Compliance with ARARS
Under Section 121 (d)(l) of CERCLA, remedial actions must attain standards, requirements,
limitation^ or criteria that are applicable or "relevant and appropriate" under the circumstances
of the release at the Site. For the Summitville Site, the promulgated Colorado Water Quality
Standards are the chemical specific ambient water quality standards applicable to the interim
remedial actions. The chemical specific surface water quality ARARs are presented in Table 7.
The National Pollution Discharge Elimination System stormwater permitting requirements are
also applicable to actions at the Site, and require implementation of Best Management Practices
for control of storm water. The Colorado Mined Land Reclamation rules are also applicable as a
fjna| benchmark against which any reclamation at the Site is measured.
Compliance with ARARs addresses whether or not an alternative will attain Federal and State
environmental laws and or provide grounds for a waiver. None of the alternatives will serve to
attain surface water quality ARARs independently, but in conceit with other interim remedial
48
-------
and final remedial actions at the Site, all the alternatives evaluated, with the exception of
Alternative 5-1, will attain all ARARs of federal and state statutes and regulations. Alternative
5-1 .will not meet remedial action objectives and will not contribute to attainment of surface
water quality ARARs in the Alamosa River.
With the exception of no action, all of the alternatives employ best management practices (BMP)
for conn-oiling storm water and thus attain the NPDES stormwater permitting requirements.
Likewise, with the exception of no action, all of the alternatives attain the narrative Mined Land
Reclamation requirements.
1.83 Criteria 3: Long-Term Effectiveness and Permanence
This criterion measures the ability of a remedy to provide reliable protection of human health and
the environment over time. The destruction and/or removal of the cyanide was the determining
factor for the type of remedy or alternative that was selected. Based on this criteria, Alternative
5-6 would provide the highest degree of long-term effectiveness and permanence, with complete
excavation and dismantling of the HLP, followed with treating all excavated spent ore materials
with water rinsing before backfilling the treated ore into the mine pits. Alternative 5-5 combines
partial spent ore removal with water rinsing of the lower sections of the HLP, and would be rated
high hi terms of long-term effectiveness and permanence. Alternative 5-3 also provides a high
degree of long-term effectiveness in controlling cyanide and metal discharges from the HLP by
pumping and treating the HLP leachate, biodetoxifying hi place the spent ore of cyanide, capping
the HLP, with continued metals removal through conventional methods and finally a bioreactor.
The bioreactor could also serve to compliment the final site closure plan. Alternative 5-1, No
Action, would not provide long-term effectiveness nor permanence. The remaining alternatives
would range from moderate to high in long-term effectiveness and permanence, depending on
type and number of remedial technologies and process options employed (see Table 10).
Criteria 4: Reduction of Toxicity. Mobility, or Volume
This criterion refers to whether a remedy reduces health hazards, reduces the movement of
contaminants, or reduces the quantity of contaminants at the Site. Alternative 5-1, No Action,
will not attain reduction of toxicity, mobility or volume. All remaining alternatives will reduce
toxicity, mobility and volume of contaminants, with Alternative 5-6, eliminating the entire
volume of the HLP and its source of cyanide, being the most effective. Alternative 5-3 reduces
the toxicity of the cyanide through treatment and will impact the mobility of metals
contamination by reducing infiltration and the generation of leachate.
49
-------
1.8.5 Criteria 5: Short-Term Effectivenes*;
This criterion refers to the period of time needed to complete the remedy and any adverse effect
to human health and the environment that may be caused by construction and implementation of
the remedy. All alternatives would expose workers to contaminants during sampling and
construction activities. Alternative 5-1 would not provide any reduction of cyanide or metals.
All remaining alternatives would show rapid reductions of contaminant levels following
initiation.
Criteria 6: Implementability
This criterion refers to the technical and administrative feasibility of a remedy. All alternatives
are implementable. Alternative 5-1, No Action, the easiest to implement, since it required no
change to existing site conditions. Alternative 5-6 is the most difficult to implement, due to the
equipment and manpower resources that must be brought to this remote location. The remaining
alternatives range from easy to moderate to implement
1.8.7 Criteria 7: Cost ' . '
This criterion evaluates the estimated capital, operation and maintenance costs of each alternative
in comparison to other equally protective alternatives. Costs are presented in Table 10. The cost
for Alternative 5-1, No Action, is the lowest and Alternative 5-6 has costs significantly higher
than the other alternatives. The present value cost for Alternative 5-1 is $261,000. The cost of
Alternative 5-2 is $13,772,000. Costs for Alternatives 5-3 and 5-4 are $18,929,000 and
$21,411,000, respectively. The cost for Alternative 5-5 is $22,923,000 and the cost for
Alternative 5-6 is $74,176,000.
1.8.8 Criteria 8: State Acceptance
State acceptance describes whether the State agrees with, opposes, or has no comment on the
preferred alternative. The State concurs in the selection of Alternative 5-3 as the interim
remedial action of the HLP.
] .8.9 Criteria 9; Community Acceptance
Community acceptance includes determining which components of the alternatives interests
persons in the community support, have reservations about, or oppose. Several commenters were
concerned with the installation and operation of the injection well system. Other commenters
were unsure that the selection of Alternative 5-3 was the best possible selection and that the
50
-------
selection process was inadequately documented. Some commenters questioned the current
condition of the HLP underliner and intermediate liners. The community response to the
alternatives is presented in the responsiveness summary, attached to this document, which
addresses comments received during the public comment period.
1.9 Selected Alternative
The selected interim remedy for cleanup of the HLP serves to prevent or reduce migration of
cyanide and/or metal contaminants. The selected interim remedy, Alternative 5-3: Injection-
Extraction Wells, Pump and Treat, Biotreatment, Recontour, Capping and Bioreactor is best
suited to allow progress toward achieving remedial action objectives and goals. This alternative
involves the installation of 21 extraction wells, pumping and treating of the contaminated water
(leachate) currently contained within the HLP, followed with biotreatment to inoculate the HLP
with cyanide-destroying bacteria. Upon completion of the biotreatment process during which all
solutions are treated and discharged, the HLP would be graded, recontoured using a 4:1 slope,
capped using a four foot layer of crushed stone covered with six inches of topsoil, and
revegetated with native grasses. A four-cell bioreactor and a surge pond would be located
downstream to serve as added protection to treat any possible acid waters generated once the
HLP is remediated. The surge pond will be designed to contain the maximum
anticipated/modelled flows which exceed treatment plant capacity. The bioreactor/surge pond
could be incorporated with all Site remedies. Analytical and laboratory tests are still underway
to refine biotreatment design parameters.
Alternative 5-3 was the selected remedy for the HLP due to the following criteria:
This alternative provides an overall protection to human health and the
environment
• The selected alternative alone will not attain all ARARs, but will attain ARARs in
concert with the other interim and final remedial actions.
• This alternative provides long term effectiveness hi controlling cyanide and metal
discharges from the HLP by pumping and treating the HLP leachate,
biodetoxifying the ore of cyanide, capping the HLP, and continuing metals
removal through conventional methods and through a bioreactor.
The alternative reduces the toxicity of the cyanide through treatment and will
impact the mobility of metals contamination by reducing infiltration and the
generation of leachate.
51
-------
The alternative provides short term effectiveness by continuing water treatment
until the benefits of the other remedial activities are realized.
This alternative can be implemented with available resources and may be
completed within two years.
The cost of this alternative is estimated at $18,929,000 for a five-year period and
is reasonably related to the anticipated environmental benefits.
1.10 Statutory Determinations
The selected remedy satisfies the requirements of Section 121 of Superfund Amendments and
Reauthorization Act of 1986 (SARA). SARA requires that Superfund remedial actions be
protective of human health and the environment. SARA also mandates that the selected remedy
attain applicable or relevant and appropriate environmental standards established under Federal
and State environmental laws except in those circumstances where a waiver is justified. In
addition, the selected remedy must be cost-effective and utilize permanent solutions and
treatment technologies to the maximum extent practicable. SARA also expresses a strong
preference for remedies that as their principal element employ treatment technologies that
permanently and significantly reduce the volume, toxicity, or mobility of the hazardous
substances. The following sections describe how the selected remedy addresses these statutory
provisions.
1.10.1 Protection of Human Health and the Environment
The selected remedy provides interim protection to human health and the environment by
pumping and treating the HLP leachate, in situ detoxification of the ore, capping of the HLP, and
continual water treatment by conventional methods initially and via bioreactor until the interim
remedial objectives and goals'can be met without treatment; and "ntil final remediation is
accomplished. The remedy will rapidly reduce cyanide concentrations and contribute towards
reducing the release of metals.
1. i Q.2 Compliance with Applicable or Relevant and Appropriate Requirements
Under Section 121 (d)(l) of CERCLA, remedial actions must attain standards, requirements,
limitations, or criteria that are applicable or "relevant and appropriate" under the circumstances
of the release at the Site. Alone, this interim action will not attain the surface water quality
Applicable or Relevant and Appropriate Requirements (ARARs) for metals in Segment 3b of the
Alamosa River. This interim action, in concert with the other interim actions at the site will
52
-------
attain the surface water quality ARARs for cyanide in Segment 3b. The selected remedy will
meet all applicable or relevant and appropriate requirements of federal and sate law for the HLP
interim response actions. No ARARs are being waived.
1.10.3 Cost Effectiveness
The selected remedy is cost-effective because it has been determined to provide overall
effectiveness proportional to its costs, the net present worth value being $18,929,000. The
selected remedy will provide long-term effectiveness and permanence; however, the duration of
bioreactor operation is unknown. The longevity of the bioreactor substrate is difficult to predict,
but should be a minimum of 3 years. Replacement of the substrate will be required in the long
term due to reduction to nutrients required for the bacteria, buildup of metal sulfide precipitation,
and bed plugging. The effectiveness of the bioreactor and the substrate longevity will be
determined in laboratory and field pilot studies. Capping will reduce the volume of water
requiring treatment
1.10.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to Maximum
Extent Practicable and Preference for Treatment as a Principal Element
In selecting the remedy for the Summitville Minesite HLP, EPA has utilized permanent solutions
and alternative treatment technologies to the maximum extent practicable. EPA identified and
screened alternatives, which as a preference, include biotreatment as a principal element
Biotreatment is accomplished through detoxifying cyanide through the CDP and metals
attenuation through the MRP. These biotreatment processes represent innovative technology
types currently being tested.
53
-------
2.0 RESPONSIVENESS SUMMARY
2.1 Responsiveness Summary Overview
The EPA held a public comment period from August 23,1994 to October 23,1994 for interested
parties to comment on the HLP FFS for the Summitville Minesite and the Proposed Plans for the
Summitville Mine.
EPA held public meetings on September 8 and October 12,1994 in Alamosa, Colorado to
present the results of the FFS and the preferred alternative as presented in the document
All comments received by the EPA prior to the end of the public comment period have been
responded to and the Responsiveness Summaries are attached to this document Transcripts are
available in the administrative record for the comments received during the September 8 and
October 12,1994 public meetings. .
22 Summary and Response to Heap Leach Pad Specific Comments
Comment 1;
A comment was received regarding EPA's rejection of the use of alkaline amendments
(based on technical implementabiliry) as shown in the table in Section 3.5 of the FFS.
Response:
The comment provided in the table relates to treatability tests on Summitville mining
waste which demonstrated alkaline additions would be quickly consumed should acid
solutions come in contact with the amended material. These tests also demonstrated very
large additions of alkaline amendments would be required for the Summitville waste
materials However, given the size and quantity of the HLP itself, any attempts to blend
alkaline material throughout the HLP would make this alternative (either by itself or in
combination with other technologies) very costly and difficult to implement Alkaline
amendments will most likely be blended into the capping material to aid revegetating the
HLP cover.
Comment 2:
One commenter did not think the selection of Alternative 5-3: Injection-Extraction
Wells/Pump & Treat/Biotreatment/Recontour & Cap/Bioreactor was adequately supported
by the documentation provided.
54
-------
Response:
The selection of Alternative 5-3: Injection-Extraction Wells/Pump &
Treat/Biotreatment/Recontour & Cap/Bioreactor is based on actual remedial efforts at
three other Minesites where cyanide heap leach practices were conducted: Cyprus's
Copperstone Mine in Arizona, Hecla's Yellow Pine Mine in Idaho, and Inland Gold and
Silver's Toiyabe Mine in central Nevada. At the Copperstone Mine, a 1.2 million ton
leach pad was treated biologically, reducing weak acid disociable (WAD) and total
cyanide levels in the heap leachate solutions from 30 to 0.2 mg/L. The Yellow Pine Mine
used biotreatment methods on a 1.3 million ton leach pad, reducing WAD cyanide from
47 to 02 mg/L hi heap leach solutions. This Site also demonstrated biotreatment
methods hi cold weather climates, similar to what will be anticipated at Summitville
where low solution temperatures and extreme cold conditions will be encountered during
operations. The Toiyabe Mine successfully treated 2.6 million tons of spent ore in two
leach pads biologically, reducing WAD cyanide from 12 to 0.2 mg/L. All three mines
accomplished these cyanide detoxifications with application rates of less thaq 0.5 tons of
solution per ton of ore treated. These facts, in conjunction with treaiability tests
completed on Summitville HLP spent ore materials, were the basis for selecting
Alternative 5-3.. Although it is stated Alternative 5-2 will achieve ARARs, this may only
be short term successes. Long term leakage of cyanide/metal complexes may result from
the inability of the water flush to reduce adsorbed cyanide present hi the HLP. Results
from the treatability test control column demonstrate water flushing was not effective in
cyanide detoxification.
Comment 3:
A commenter thought the injection well grid, shown on Figure 5-5 in the Heap Leach Pad
FFS, should have the same number of wells displayed as the number of wells proposed for
installation. . .
Response: •
Figure 5-5 shows a typical well grid spacing for the HLP and is for presentation purposes
only. The costs presented in Table 5-3 (21 wells) of the FFS are based on the number of
wells estimated to be required given the area! extent of the HLP and areas of influence of
each well. Cost estimates listed hi Table 5-3 of the FFS are an order of magnitude cost
estimate (-30%, +50%) as directed in EPA Office of Soil Waste and Emergency
Response (OSWER) Directive 9355.3-01, Guidance for Conducting Remedial
Investigation and Feasibility Studies Under CERCLA (Interim Final, October 1988).
They will be updated once remedial design information has been obtained.
55
-------
Comment 4:
A comment was received indicating that the description of Alternative 5-3 should have
addressed the problems associated with the intermediate liners and how the proposed
injection/extraction wells will enhance the current rinse program.
Response:
The operating condition of the existing solution application system (the underdripper
system) is very much in question, particularly in the lower sections of the HLP where the
overall weight of the deposited ore materials may have crushed the system so that its
solution distribution capabilities are impaired. Higher levels of cyanide may still exist in
these lower sections of the HLP. The injection-extraction wells were selected on the
basis they could be installed in a grid pattern which would be more effective in reaching
the isolated regions of the HLP. With the injection-extraction wells, packers can be
inserted into individual wells above and below certain HLP horizons to direct solutions in
a horizontal flow pattern away from each well, facilitating the cyanide removal capability
of the biotreatment process.
CommentS;
One commenter indicated that the HLP Investigation Report did not use chemical specific
ARARs for surface water in Section 6.2.4 of the FFS.
Response:
The State of Colorado has promulgated a standard which states downstream use has to be
protected, and this Site has to comply with this standard. Also, the calculations cited
from Section 6.2.4 of the FFS and included in Tables 6-9 and 6-10 of the HLP
Investigation Report list the chemical specific ARAR for cyanide, which for Stream
Segment 3b is 0.005 mg/L. In both tables, the chemical specific ARAR for cyanide is the
basis for the more stringent target
Comment 6:
A commenter felt that the FFS did not present sufficient design parameters to justify the
use of biotreatment technology.
Response:
The guidelines for completing feasibility studies, as detailed in OSWER Directive
9355.3-01, Guidance for Conducting Remedial Investigation and Feasibility Studies
l/nder CERCLA (Interim Final, October 1988), suggest reaching the alternative selection
process as quickly as possible in order to complete the comparative analysis for selected
remedies. The design information requested by the commenter is beyond the feasibility
study process, and will be supplied at a future date in site-specific design documents.
Treatability tests have justified the selection of the biotreatment process.
56
-------
Comment 7:
A comment was received indicating that the FFS should have stated why the bioreactor,
used in providing long term metals attenuation, is necessary.
Response:
There are concerns with the ground water re-establishing itself within the HLP over a
period of time. Short term prospects indicate acid rock drainage (ARD) may not be a
problem; however, with elapsed time, there may be a concern. The bioreactor would
serve as added insurance to trim all discharges emanating from the HLP (it is possible the
bioreactor design will incorporate all drainages from the Site). It is suggested the reader
refer to the Cropsy Waste Pile Amendment Testing Final Report prepared by
Environmental Chemical Corporation, July 1994 which is part of the administrative
record.
Comment 8:
One commenter indicated that the analytical methods for quality control should have been
provided in the FFS.
Response:
A listing of analytical methods of quality control measures will be provided in the overall
Site Remedial Investigation/Feasibility Study (RI/FS) to be issued at a later date.. It is
beyond the scope of this document to supply this information. However, the methods can
be found hi the administrative record in the numerous Sampling and Analysis Plans
(SAPs), as well as the overall Quality Assurance Project Plan (QAPP) prepared for the
Site.
. Comment 9;
A commenter indicated that if the final remedy for the HLP had been selected it should be
presented in the FFS.
Response:
Interim actions start the overall process of site remedy. The major remedial action
objectives for these interim actions have been identified as reduction in acid mine
drainage, cyanide detoxification and waste pile minimization and containment. These
objectives will not change for the overall site remedy so that there will not be any conflict
of issues between interim actions and final site remedy. The short term goals will also
serve to protect the environment
57
-------
Comment 10:
One commenter stated that the EPA should know if complexes of cyanide and sulfur and
thiocyanate are present and if they pass through the current water treatment system.
Response:
Other complexes of cyanide are known to exist From an historical perspective, when
Summitville Consolidated Mining Company, Inc. (SCMCI) operated the mine,
thiocyanate levels reached 167 ppm (at the barren solution pond, December 1987). The
most recent information on file, October 1992, indicate thiocyanate levels are now 0.1-0.3
ppm. Thiocyanate passes through the current water treatment system. To date, it has not
been established thiocyanate is a contaminant of potential concern, requiring monitoring.
This will be established at a later date after toxicity levels have been thoroughly
identified.
Comment 11;
A commenter indicated that the cyanide content in the drainage stream downgradient of
the HLP should have been provided in the FFS. This commenter further states that if the
water being returned to the HLP has a pH of ZJ to 3.5 then the HLP has the potential to
generate HCN gas.
Response:
The cyanide concentration detected in downstream drainages is variable, depending on
date in which monitoring was completed. Any cyanide-contaminated solutions reaching
a pH of 2.5 would have previously off-gased as HCN. All solutions in the French drain
sump are now being caught and neutralized before being returned to the HLP.
Comment 12:
One commenter questioned whether the day liner beneath the HLP is intact and where the
cyanide leachate is flowing into the French drain. This commenter indicated that stopping
the cyanide source would stop the cyanide problem.
Response: .
The clay liner is not intact The quantity of ore material placed on top of the liner
precludes identifying the location of the breach and/or repairing any tears short of
dismantling and hauling off significant quantities of HLP material.
Comment 13;
Another commenter questioned whether the polyethylene liner was breached or if poor
application practices resulted in the cyanide leakage.
58
-------
Response:
All information on file support the conclusion the liner was torn, with solution leaking
into the French drain system underneath the HLP. Leakage was not due to poor
application practices. The overall integrity of the intermediate liners is not known. Some
may be in good shape, while others appear not to be intact The reader is referred to the
Heap Leach System Report, prepared by SCMCI, May 27,1992 which is part of the
administrative record.
Comment 14;
A commenter questioned whether any chemicals other than hydrogen peroxide or
processes such as SO2 or Caro's acid treatment were evaluated.
Response:
Chemicals other than hydrogen peroxide were evaluated through a Request For Proposal
(RFP) effort on water treatment processes initiated in November 1993 and preceding the
FFS. Evaluations of the various proposals demonstrated change outs from the existing
system would be costly and time consuming to complete. The RFP package is part of the
administrative record on file with EPA, Region Vm. Additional studies in the ongoing
RI/FS were also completed, and include evaluations of the sulfur dioxide process, but not
Caro's acid treatment
Comment 15;
One commenter questioned whether investigations were performed to evaluate the
potential of .adding a bactericide to the HLP to prevent ARD generation. The commenter
recommended current practices used by MV Technologies.
Response:
The MV Technologies Process was evaluated for possible use in other areas of the Site.
It was not evaluated in the HLP remedy selection because it's an acid abatement process
incorporating a bactericide for retarding acid generation. Although the HLP materials
contain some sulfide mineralization, the immediate problem with the HLP is cyanide
detoxification. Since bioremediation, using bacteria, is the selected remedy to complete
the cyanide detoxification, the EPA believes the addition of a bactericide may pose
adverse impacts on the selected remedy. Subsequent acid generation after bioremediating
the HLP will be controlled by limiting amount of oxygen that will infiltrate by capping
and covering the HLP.
59
-------
Comment 16:
A comment was received regarding the capital costs of cap material for Alternatives 5-2
and 5-3. The commenter questioned whether the costs shown included reclamation and
monitoring of the location where the material was mined.
Response:
The capital costs of $7,000,000, as shown in Tables 5-2 and 5-3 of the FFS, are for
quarrying, crushing and transporting the material to the HLP. Monitoring costs would be
included in the quarrying costs. No reclamation costs are included, but they would be
low since the amount of areas disturbed would be minimal, only sufficing the amount of
extra capping materials required. The study only focused on on-site materials, no other
sources of capping material have been considered.
Comment 17;
One commenter indicated that the aerobic and anaerobic of the HLP may not be conducive
to bacterial activity.
Response:
The biotreatment process to be used at the Site will incorporate a mixture of aerobic and
anaerobic bacteria strands which have been cultivated from micro-organisms retrieved
from the Site. Both types of bacteria will be commingled in solutions introduced into the
HLP. The aerobic strands will be effective in detoxifying those zones where oxygenated
conditions exist (upper levels); while the anaerobic strands migrate to the lower reaches
where non-oxygenated conditions exist Treatability tests have been conducted on
saturated and non-saturated zones of HLP material, and test results have confirmed
cyanide detoxification with both types of bacteria.
Comment 18;
A commenter indicated that during spring runoff, the water level in the HT.P Dike 1 might
exceed the capacity of the water treatment plant and result in overtopping of the dike. The
commenter felt that provisions should be made for adequate pumping and water treatment
capacity to prevent overtopping.
Response:
Alternative 5-3 is initiated with the installation of the injection-extraction wells, followed
by a pump and treat step. During the pump and treat, cyanide-ladened solutions currently
held within the HLP will be withdrawn and treated with bacteria as the solution flows
through tanks added to the water treatment plants. During the pump and treat activity,
solutions with bacteria will be recycled back to the HLP to start the inoculation of the
HLP. The recycled flows will be at reduced flows so that the net effect is to reduce the
solution levels within the HLP. The main reason for testing saturated conditions in the
60
-------
treatability work is to confirm bacterial activity can be initiated while the pump and treat
step is underway. Alternative 5-3 is very concerned with reducing current solution levels
within the HLP for the primary reason spring runoffs have to be anticipated and managed.
Comment J19:
Two commenters questioned whether cyanide "hotspots" would remain beneath the
intermediate liners or in pockets and if these areas would be reached by a bacteria
containing rinse.
Response:
The injection-extraction well system was selected because a more positive control of
solution flows through the HLP can be maintained with such a system. Packers can be
inserted into wells to direct solutions to various "hotspot" areas (refer to the Response
given on Comment 4). The bacteria, once it has been introduced to the HLP, will have a
certain amount of diffusion capability, seeking its food source which hi this case is the
cyanide itself. If after attempts to reach the isolated areas, "hotspots" still remain, any
subsequent precipitation event will most likely not result in subsequent solubUizmg the
isolated cyanide from the HLP.
Comment 20:
A commenter suggested that the proposed injection wells may become plugged due to
biological activity.
Response:
Designs can be incorporated into the injection-extraction well system for flushing
capabilities.
Comment 21;
One commenter indicated that the French drain would continue to be a source of metals
and acid after HLP remediation because it is connected to the Cropsy Waste Pile.
Response:
The Cropsy Waste Pile (CWP) Removal Action should prevent the CWP from being a
major source of acid mine drainage (AMD) because waters that have flowed into the
CWP will, to a large extent, be intercepted upstream and diverted away from the HLP.
Any residual AMD emanating from the CWP remnant should be manageable and can be
diluted with other water discharges.
61
-------
Comment 22:
A commenter suggested that continuous rinsing of the HLP would cause caving and
therefore the number of injection wells and their placement would be impossible to
determine.
Response:
During the design phase, best professional judgement of the design engineers will be used
to determine the appropriate location and design of the wells. During operation,
monitoring will determine the overall success.
Comment 23:
A commenter noted that the TAG proposal for water treatment win make the bioreactor
unnecessary.
Response:
EPA recognizes the TAG's proposal, treatment of water at the bottom of the Site, will
make the bioreactor unnecessary. The TAG proposal, however, does not prevent the
further generation of AMD or the control of it at its source. EPA believes the decreasing
of AMD generation provides a more permanent solution to the risks to human health and
the environment at the Site.
Comment 24;
The TAG proposed that Alternative 2 be reassessed and modified:
Reduced Heap Leach Pad elevation will avoid redox shifts from aerobic to
anaerobic conditions and will make treatment more effective.
The water levels in the Heap Leach Pad will be raised and the remainder of
the pad inundated to infiltrate all cyanide sources.
• Removing Heap Leach Pad material below dike level will allow complete
inundation of all remaining "hot spots". This material can be moved into the
mine pits.
• EPA should use existing application systems and devices, or use exfiltration
beds similar to "leach fields" of septic systems to introduce rinse fluids to the
Heap Leach Pad.
• The TAG proposed that the effluent from the French Drain be treated until it
meets accepted levels or standards. As this is likely to extend past the period
62
-------
contemplated under Alternative 3, the relative value of TAG's water
treatment proposal (see following section for its description) is enhanced.
Finally, the Heap Leach Pad remediation plan needs to be integrated into the
overall site reclamation plan, particularly the storm water management plan,
grading plan, and revegetation plan. As has been pointed out, it also needs
integration into the water treatment plan.
Response:
Flooding the HLP with water was one of the earlier alternatives (refer to Section 3.0)
considered and rejected because of high costs and implementability factors. Potential
stability problems with Dike No. 1 would have to be fully resolved. Costs and time to
conduct the necessary geotechnical surveys would be excessive and lengthy. To retain
the proposed volume of solution to be held within the HLP, the existing dikes may
require keying into bedrock to prevent any leakages and to resolve any structural
weaknesses. Due to the high fracture zone in the surrounding topography, keying may
require extensive grouting, adding to the high capital costs.
Removing the top section(s) of the HLP to the mine pits will return additional material, in
excess with what has been placed in the pits to date. This would raise substantially the
elevation of the backfilled material in pits, requiring a major regrading plan to
accommodate this material. Although this would not constitute a major reason for
rejecting the partial removal of HLP material, it does add substantially to haulage and
disposal costs of HLP materials. It should be noted Alternative 5-5 deals with a partial
removal of the HLP, and it was rejected due to high costs with no substantial gain in
overall protection of human health and the environment
The overall remediation plan for the Site will take into consideration the interim action
plans, integrating them in with the storm water management, regrading, revegetation,
water treatment and other plans.
63
-------
23 Summary and Response to General Comments
Introduction On August 16,1994, the United States Environmental Protection Agency, Region
VIE (EPA), issued four Focused Feasibility Studies (FFS) relating to proposed remedial action
work at the Summitville Mining Site. These four FFSs relate to: (1) Cropsy Waste Pile,
Cleveland Clifis Tailing Ponds, Beaver Mud Dump and Mine Pits; (2) Heap Leach Pad; (3)
Water Treatment; and, (4) Site Reclamation. EPA requested public comment on the four FFSs
and extended the deadline for comment to October 24,1994.
Comment
A number of commenters complained chat some of the alternatives evaluated by EPA in
these FFSs are already being implemented without EPA having followed the remedy
selection and public participation procedures of the NCP.
In particular, various commenters objected to the continued placement of the Cropsy
Waste Pile into the Mine Pits pursuant to an emergency-like schedule, despite public
comment on EPA's previously issued Engineering Evaluation/Cost Analysis (EE/CA). This
prior public comment stated such action was inappropriate because EPA did not consider
the feasibility of capping the Cropsy Waste Pile in its original location and EPA failed to
consider potential short and long term impacts on acid mine drainage. Commenters
believe removal of the Cropsy Waste Pile and its placement in the Mine Pits will exacerbate
site conditions.
In spite of these public comments, EPA awarded a contract in July 1994 to complete the
excavation and relocation of the Cropsy Waste Pile (CWP), Beaver Mud Dump (BMD) and
Summitville Dam Impoundment (SDI) into the Mine Pits according to the EE/CA and
Action Memorandum. Commenters now object to EPA selecting the placement of the
Cropsy Waste Pile, BMD and SDI into the Mine Pits as a remedial action alternative.
Commenters have suggested that by selecting the'EE/CA response action as the interim
remedial action, EPA has "pre-selected" the remedial action for the Cropsy Waste Pile and
has circumvented the public participation procedures mandated by the Comprehensive
Environmental Response, Compensation and Liability Act of 1980, as amended (CERCLA)
and the National Contingency Plan (NCP). .
Commenters note that both CERCLA and the NCP establish specific steps and procedures
that EPA must follow in selection a remedy for all or a portion of a CERCLA Site. See.
generally. 42 U.S.C. 9604, 9621; 40 C.F.R. 300.430 and claim that EPA has not followed
the NCP procedures. The commenter states that EPA justifies the implementation of the
allegedly "pre-selected" remedy by arguing that the public participation undertaken
during the EE/CA process last summer satisfies the public's right to participate hi the
remedial selection process for the Target Areas.
64
-------
Response:
Excavation and consolidation activities associated with Cropsy Waste Pile, Beaver Mud
Dump, Summitville Dam Impoundment (formerly called the Cleveland Cliffs Tailings
Pond), and Mine Pit were initiated under an EPA non-time critical removal action
pursuant to Section 300.415 of the National Contingency Plan. Such removal activities
are appropriate when, among other things, "excavation, consolidation, or removal of
highly contaminated soils from drainage or other areas... will reduce the spread of, or
direct contact with, the contamination." See. Section 300.415(d)(6) of the NCP at 55
Fed. Reg. 8843 (March 8,1990). Once EPA determines such removal actions are
appropriate, response actions shall begin as soon as possible to abate, prevent, minimise,
or eliminate the threat posed by the contamination to public health, welfare of the
environment See. Section 300.415(b)(3) of the NCP at 55 Fed. Reg. 8843 (March 8,
1990).
According to the NCP, if a six-month planning period exists before EPA initiates a
removal action, EPA must conduct an Engineering Evaluation/Cost Analysis (EE/CA).
This analysis, although not as extensive as a Remedial Investigation/ Feasibility Study,
identifies the objectives of the removal action and analyses the various alternatives that
may be used to meet these objectives, based on the alternative's cost, implementability
and effectiveness. The EE/CA is then released for public comment, according to the
public participation procedures established in Section 300.415(m)(4). Finally, after a
minimum 30-day public comment period, EPA issues an Action Memorandum which
documents EPA's selection of an appropriate non-time critical removal response action.
See also. "Guidance on Conducting Non-Tune Critical Removal Actions Under
CERCLA," EPA/540-R-93-057, Publication 9360.0-32 (August 1993).
EPA meticulously followed the NCP-prescribed procedure in proposing and selecting the
EE/CA-based non-time critical removal for the Cropsy Waste Pile, Beaver Mud Dump,
Summitville Dam Impoundment (formerly called the Cleveland Cliffs Tailings Pond),
and Mine Pit (collectively, the Target Area). EPA published its EE/CA in July of 1993,
solicited and accepted public comments on the EE/CA until early September of 1993,
responded to those comments in its "Responsiveness Summary to the Engineering
Evaluation/Cost Analysis for the Cropsy Waste Pile, Beaver Mud Dump, the Cleveland
Cliffs Tailings Pond (now called the Summitville Dam Impoundment), and Mine Pits,
Summitville Minesite, Rio Grande County, Colorado," and issued its Action
Memorandum on September 24,1993. EPA let a contract to begin implementation of
this part of the EE/CA-based removal action in July 1994.
EPA is not arguing that providing the public the opportunity to comment on the EE/CA is
sufficient to substitute for soliciting public comment on the Target Area FFS and
Proposed Plan. EPA agrees that the NCP does not allow EPA to satisfy its public
participation obligations for a proposed plan by reference to another document EPA also
agrees that the analysis EPA conducts to evaluate removal alternatives differs greatly
65
-------
from the analysis conducted to evaluate remedial alternatives. For non-time critical
removals, EPA evaluates the alternatives in terms of effectiveness, implementability and
cost alone. The evaluation of remedial alternative is conducted using the nine criteria of
Section 300.430 of the NCP. The two sets of evaluation criteria are not synonymous.
EPA, however, did fully comply with the NCP-prescribed procedures for screening,
proposing and selecting remedial alternatives for the Target Areas in its Focused
Feasibility Study, Proposed Plan and Interim Record of Decision (ROD). The removal
alternative previously selected in the Action Memorandum was one of the alternatives
evaluated during EPA's remedy selection process. EPA took public comment on the
relative merits of all alternatives evaluated in the FFS vis-a-vis the nine NCP criteria and
proposed its preferred alternative in a Proposed Plan, issued in accordance with Section
117 of CERCLA. The alternative previously selected in the Action Memorandum, as
expanded in the FFS and Proposed Plan, met the threshold remedy selection criteria of
the NCP and provided the best balance of the NCP's "balancing" and "modifying"
criteria. It was selected as the appropriate remedial action in the Interim ROD for the
CWP. In accordance of the remedy selection criteria of Section 300.430(e) and (f) of the
NCP.
EPA therefore selected both the EE/CA-based removal action and interim remedial action
according to the different, applicable standards and procedures of the NCP. The fact that
the two response actions are similar does not make the implementation of the previously
selected removal action illegal or invalid. Moreover, with the letting of the July 1994
contract, EPA was merely initiating the implementation of its validly selected removal
action. EPA's publication of the Target Areas FFS and Proposed Plan has no bearing on
and should not interfere with EPA going forward with this removal action.
Comment 2:
One commenter strongly recommends that EPA delay removai'of the Cropsy Waste Pile
until all the potential ramifications have been properly evaluated by the public and by
competent technical consultants. Such an evaluation should be conducted after EPA's
"Use Attainability Study," which will characterize and evaluate downstream effects from
the Site, is completed. The commenter believes there is no reason to implement this remedy
on an expedited schedule.
Response:
The Use Attainability Study is being completed by the State of Colorado, Division of
Minerals and Geology. The findings of this study will be incorporated into EPA's final
response action for the Site. In the meantime, EPA believes the environmental benefits
that will be gained from the implementation of interim remedial actions at the Site far
outweigh the continued releases of mine waste for the Cropsy Pile.
66
-------
Comment 3;
Commenters requested an explanation of EPA's rationale for issuing interim rather than
final RODs. These commenters feel EPA has no legal or technical basis for issuing IRODs
and that there will be additional costs associated with first implementing an interim
remedy prior to making a final remedy selection. They also expressed the belief that some
of the interim remedial actions may actually exacerbate site conditions and contamination
or may prove ultimately incompatible with final remedial action(s) for the Site.
Response:
According to EPA guidance, interim remedial actions are appropriate to "take quick
action to protect human health and the environment from an imminent threat in the short
term, while a final remedial solution is being developed." See. "Guide to Developing
Superfund No Action, Interim Action and Contingency Remedy RODs," US EPA,
OSWER Publication 9355.3-02FS-3 (April 1991), at p. 5.
Deterioration of site conditions will lead to continued and heightened exposure of
sensitive human and ecological populations to heavy metals and chemicals (e.g. cyanide)
used by Galactic and others in their mining operations. The IRODs institute temporary
measures to stabilize the Site and prevent further migration of contaminants of concern
from the Site into surrounding soil, air and water media. Further, the types of interim
actions selected in the IRODs, such as the relocation of contamination from one portion
of the Site (CWP) to another (Mine Pits) and the installation of caps to prevent further
migration of contaminants are exactly the types of response EPA guidance states are
appropriate to implement as interim remedial actions. See, "Interim Final Guidance on
Preparing Superfund Decision Documents," OSWER Directive 9355.3-02 (June 1989), at
Chapter'9.
Given the existing Site conditions, EPA is certain that filling the Mine Pits will
significantly reduce the flow into the Pits and prevent discharges of acid from the Mine
Pits into underground workings and ground water. Relocating other mine waste features
such as the Cropsy Waste Pile, Beaver Mud Dump and Summitville Dam Impoundment
to the Mine Pit will also mitigate these areas as sources of acid mine drainage. Capping
the Mine Pits will serve to eliminate or significantly reduce the movement of
contaminants of concern through water and air pathways. Treatment of surface water and
detoxifying the Heap Leach Pad will eliminate releases of metals and cyanide. Overall,
the implementation of interim response actions will quickly reduce the imminent threats
to human and environment receptors at and around the Summitville Minesite. EPA will
also continue to monitor the progress of these remedies in eliminating or reducing the
release of hazardous substances from the Site and will determine what, if any, final
remedial actions are necessary to address the remaining risks at the Site.
67
-------
Comment 4;
Many commenters sought clarification which applicable or relevant and appropriate
requirements (ARARs) of federal and state statutes and regulations must be complied with
for remedial actions at the Site. Commenters wanted an identification of which ARARs
will be met with by the interim actions and which ARARs will be waived. One commenter
cautions against the use of "Technical Practicability Waivers" as shortcuts in the
remediation.
Response:
The ARARs clarification is provided in the specific Responsiveness Summary on
ARARs. Each IROD also identifies the relevant portions of federal and state
requirements are being complied with or waived in the implementation of the interim
remedial actions. Commenter should be assured that all ARARs waived with the
selection of interim remedial action will be re-evaluated for the final remedial action(s)
for the Site.
Comment 5:
One commenter noted that each of the FFSs states an "observational site approach" will be
taken as part of EPA's interim remedial actions. This commenter believes that an
observational approach may be an effective approach to site remediation, provided that all
the possible outcomes of the proposed action are identified, evaluated and monitored. The
commenter suggested that for potential outcomes that may have adverse consequences, the
impacts associated with those outcomes and the probability of their occurrence must be
qualitatively defined. If adverse consequences are likely, or that site conditions could be
make more complicated and problematic, then implementation of the proposed remedy
must be reconsidered. Finally, the commenter declared implementation of a remedial
action without an overall plan for each dealing with range of the potential outcomes is
inconsistent with a responsible observational approach at a complex site like the
Summitville Minesite.
Response:
As discussed in the "Analysis of Alternatives" section in each of the IRODs, EPA has
considered all the relative merits and detriments of the potential remedial actions
evaluated "Potential adverse consequences" of implementing the alternatives was
evaluated, as was EPA's ability to deal with these potential adverse impacts when EPA
reviewed the overall protection to human health and the environment, long-term
effectiveness and permanence, short-term effectiveness, implementability criteria of the
NCP. The interim response actions selected in the IRODs represent the alternatives that
provide the best balance of meeting these criteria. EPA will employ the "observational
approach" to continue to evaluate these interim remedial actions' effectiveness in meeting
these NCP criteria, EPA's remedial action objectives and performance standards and to
68
-------
determine what, if any, additional final remedial actions are necessary to ensure that
human health and the environment are protected against unacceptable risks posed by
hazardous substances remaining at the Site.
Comment 6:
A number of commenters are concerned about EPA's estimate of costs to be expended at
the Summitville Site are too low. Commenters have calculated those costs (both removal
and remedial) as exceeding EPA's S120 million estimate. They are concerned that the
staggering amounts for interim response do not include the cost of the final remedy or
remedial investigation/feasibility studies presently being conducted at the Site.
Response:
The commenters are correct in their observation that EPA's initial cost estimate has been
exceeded with the collective costs of the interim remedial actions selected in the ERODs.
The alternatives selected in the ERODs were screened for cost, and EPA believes that they
are cost-effective. As studies at the Site provide additional information and as remedial
actions are implemented, costs for remediation of the Site will continue to be reassessed.
Comment 7;
Commenters object to the backfilling of the Mine Pits and the plugging of the Reynolds
Adit, since in their view, these actions preclude a future beneficial use, that of re-mining.
The commenters believe that EPA's remediation activities should be immediately
terminated or suspended until the impact to future mining uses can be thoroughly
evaluated.
Response:
None of the proposed or completed EPA activities preclude further mining activities at
the Site. However, any future mining activities must be consistent with and not interfere
with the response actions EPA has implemented at the Site. EPA's remedial actions are
intended to prevent the exposure of humans and ecological populations to hazardous
substances. Any future mining activities that do not exposure these populations to
hazardous substances may be acceptable to EPA. It is anticipated, however, that EPA
will have to review any future mining plans to ensure the protection of human health and
the environment
Comments:
Commenters object to EPA's lack of a comprehensive Record of Decision for the Site and
the implementation of parallel or isolated and disjointed actions at the Site without any
overall plan or remedial strategy for the Site. To remedy this lack of coordination, the
commenters suggest that an independent board of technical experts review and select Site
response actions.
69
-------
Response:
EPA believes that the interim remedial actions selected in the IRODs provide a
comprehensive, coordinated approach to addressing the risks at the Site. Specifically,
EPA believes that all the remedial measures to be implemented according to the IRODs
will go a long way in improving sitewide water quality by controlling surface run-on and
run-off, erosion, leaching and metals and other contaminant loadings to the Alamosa
River.
Empowering an independent board of technical experts to review and select remedial
actions at the Site is improper under the Superfund law. Congress explicitly charged
EPA with the authority to select response actions to cleanup releases of hazardous
substances under the CERCLA Section 121 of CERCLA. In feet, this section of
CERCLA unequivocally states that "the President shall select appropriate remedial
actions determined to be necessary to be carried out under section 104 or secured under
section 106 which are in accordance with this section, and to the extent practicable, the
national contingency plan..." [emphasis added]. The President has delegated that
authority to select response actions at Superfund sites to the Administrator of EPA. The
procedures the Administrator must follow in selecting these cleanup actions are contained
the National Contingency Plan.1 The NCP provides that affected and interested parties,
such as States, PRP and citizens are given the opportunity to participate in the selection
process, but it is clear that the Administrator retains the responsibility to select the
appropriate remedy.
Thus, while EPA welcomes input from the community and neutral third parties
concerning the actual health risks from lead-contaminated mining wastes, EPA cannot
abrogate statutory responsibility to be the decision maker in selecting remedial actions for
Superfund sites. EPA can also not allow a third party to determine the appropriate scope
of EPA's remediation plan, smce it is our experience'm identifying health and
environmental risks and designing the remedies to address them that Congress relied
upon when it empowered us with the authority to select and implement remedial actions
under Superfund.
Comment 9:
One commenter noted that downstream impacts are currently being ignored and avoided
despite the above stated Remedial Action Objectives. Avoidance of downstream impacts
1 See, e.g. Section 120(eX4) of CERCLA (where if the head of the relevant federal agency and die Administrator
of EPA cannot reach an agreement of the remedial action to be selected, the Administrator selects the remedy).
70
-------
adversely affects Terrace Reservoir, household and municipal wells and allows agricultural
land to further degrade.
Response 9:
Due to the Chandler Adit drainage, all downstream targets are being addressed as quickly
as possible. All three areas mentioned above are part of major research efforts included
in the justification of remedial actions at the Site. Terrace Reservoir is currently
undergoing a study conducted by the U.S. Geological Survey. Agricultural lands have
undergone several studies, including those conducted by Colorado State University. With
regard to household water use, local water supplies have been sampled twice and are
undergoing long-term water sampling.
Comment 10;
The same commenter stated a site drainage plan, which provides control for
surface/subsurface drainage, storm water and sedimentation management and non-point
source collection/ treatment, is needed.
Response:
A site drainage plan has been implemented. A copy of the plan is available in the
Administrative Record.
Comment 11:
One commenter identified a need for a waste management plan.
Response:
A number of the IRODs have elements is designed to meet waste management ARARs.
The Sampling and Analysis Plans describe how investigative derived wastes are
managed. Also, used oil is being recycled and, as stated in the Focused Feasibility Study,
sludge produced on-site is being recycled for metals recovery.
Comment 12;
One commenter is concerned that EPA does not have sufficient date to establish the
Summitville Dam Impoundment (SDI) as a source of sulfide-rich tailings and metals-laden
acidic water discharged to Wightman Fork. The lack of this data calls into question the
need to remediate the SDI at all, or at least the nature and extent of such remediation. The
commenter suggests EPA collect additional data regarding the nature and extent of
contamination at the Beaver Mud Dump (BMD) and SDI before proceeding with
remediation of these areas.
71
-------
Response:
Historically, the Summitville Dam Impoundment, and the Beaver Mud Dump area have
been of significant concern to regulators from the State. Water discharges emanating
from these materials has been recorded as being of poor quality. Based on existing data,
historical precedent, and current sampling and analysis information, EPA determined that
the SDI and BMD are significant contributors of man-made AMD at the Site. Data
collected by Anaconda prior to SCMCI operations states that the mill tailings disposed of
in this area are strong AMD generators. Movement of these sources and the Cropsy
Waste Pile to the Mine Pits allows capping of four AMD sources in one action.
Comment 13;
One commenter argues that the FFSs and Proposed Plans fails to comply with the NCP
because: (1) these documents evaluate the "No Action" alternative for the Site as a whole,
rather than by the subject matter of each interim remedial action, (2) they fail to consider
naturally-occurring background concentrations of metals and acids in EPA's analysis of
alternatives, and (3) compliance with ARARs and/or ARAR waivers have not been
identified with any amount of specificity.
Response:
Alternative No. 1 for each of the Focused Feasibility Studies is a No-Action Alternative
related to that particular portion or media of the Site.
Naturally-occurring background levels of metals and acids were taken into account when
evaluating ARARs for the interim remedial actions. For example, EPA determined it was
appropriate to waive the Segment 3b stream classification as an applicable requirement
that must be met by the IRODs because of the historic contributions of metals and acids
from naturally-occurring sources. EPA will determine if this ARAR should be waived in
any final ROD(s) for the Site when additional background and load reduction information
is collected.
Comment 14;
Cleveland-Cliffs Iron Co. and Union Pacific Resources Company submitted information
regarding their (or their predecessor-in-interest's) operations at the Site, their analysis of
the current state of CERCLA.case law related to liability and legal arguments evaluating
their lability at the Site. These commenters also requested that EPA refer to the area
adjacent to the Beaver Mud Dump, which EPA has referred to as the Cleveland-Cliffs
Tailings Pond, as the Summitville Dam Impoundment or some similar appellation.
Response:
While EPA appreciates information regarding parties' prior activities at the Site,
particularly if this information supplements EPA's CERCLA 104(e) information requests
72
-------
or helps EPA to characterize the wastes at the Site, EPA believes a submission that
purports to provide comments on an FFS and Proposed Plan is an inappropriate forum to
state one's view of its liability at the Site. Such comments are more appropriately
submitted as part of a party's response to EPA's CERCLA Section 104(e) request, EPA's
Notice Letter or in confidential settlement correspondence between EPA and the
submitting party. A specific response to Cleveland-CliffTUPRC's legal arguments will be
forwarded under separate cover.
Without any qualitative judgment on the merits of Cleveland-Cliff/UPRC's legal
arguments, EPA nonetheless agrees to hereafter refer to the area below the Beaver Mud
Dump as the Summitville Dam Impoundment Corresponding changes to this
nomenclature will be made in all future EPA documents.
RESPONSIVENESS SUMMARY: GENERAL WRITTEN COMMENTS RECEIVED FROM
CITIZENS AT LARGE OF THE SAN LUIS VALLEY
These written comments represent the universe of comments received through the end of the public
comment period.
Comment 15;
To whom it may concern: My name is Roger Gallegos I have lived in the San Luis Valley just
about all my life. Before the Summitville Mine came to exist, life was good. After they
exploited the government and us, life became much more difficult Take for instance, when
we would water our fields, we could catch fish in our ditches. Another thing I have noticed is
the crop yield. Before the mine came in my meadow would yield 3000 to 3200 bales of hay.
When the mine had there spills I yielded 1642 bales. My best year while the water quality
improved was about 2853 bales. Now this may not sound important, but it is. I used to sell
hay for a Irving, and now I feed it to my cows. The mine has hurt my family in the pocketbook.
We have all been hurt by the mine in this community. The government should never have let
them start to begin with. Galactic Mining should be made responsible for the clean up. then
the Government for allowing them to do mis. Since the mining company has gotten away with
this, we should not be made to suffer for other peoples mistakes. I say Summitville should be
cleaned up and restored, and our water be put back to normal. My Great Grandfather made
a living with my ranch, as did my Grandfather and Dad. I want my kids and their kids to
continue making a living on what is theirs. They have that right, and not be forced to suffer
for what someone else was allowed to do. I myself believe the plan to filter the water down
below where die creeks meet, is the best idea. That system for 8 million, could save money and
work. Thank you for listening. The Gallegos Family. [Letter; undated; no other data given]
73
-------
Comment 16:
Dear Ms. Williams: As a farmland owner with land irrigated from the Alamosa River I am
deeply concerned and worried what the continued use of the contaminated water will
eventually do, not only to the land, drinking water from the wells, but also to the livestock and
products which are ultimately consumed by the general public. There are those who say it has
no ill effects on crops or livestock - but for how long. I do know it has played havoc with the
steel structures in the irrigation system. I'm under the Capulin Ditch and we have had to
spend over 540,000.00 replacing all steel structures. I may say that I was Water Commissioner
for this district and know the Alamosa River quite welL In this time I never saw when so many
irrigation structures all deteriorated in such short time. As for those who say there never were
any fish in the Alamosa River - it is not true. Why else would the Game and Fish Department
consider it a fishing stream. People would ice fish all winter in the Terrace Reservoir up to the
time the mine started to dump the mess into the stream. I have lived here all my life and can
remember when we were little Dad would take us fishing there. As for the different options
to solve the problem it seems to me one that would treat all the water before it got into the
Alamosa River would be the one - probably in just one pond. Thank you Sincerely, Leo B.
Gonzales [Letter; dated Oct 19,1994; address and phone number given]
Comment 17:
Dear Ms. Williams & EPA Summitville Team: Although I may be writing too late for the case
record, perhaps your comment period's been extended; in any case, the information leading
me to voice my concerns reached me after the original deadline. Your recommended plans
generally seem to stress reliance on systems that won't need too much up-keep once set in
place. The biotreatment aspect sounds favorable. However, it has come to my attention that
"caps" or "plugs" contributed to poorer water quality late in this year's irrigation season,
since the caps rechanneled contaminated water into other drainage channels that weren't
serviced by your water treatment faculties. This indicates two planning factors to me: 1. you'll
want to assess where water win eventually seep out before yon start filling the mine pits with
waste materials that are likely to displace ground water, and 2. it would make most sense to
locate your water treatment nnit(s) as far downgradient as possible, even if this entails
relocation of the existing facilities. I was also surprised that the reclamation plan 'mentions
no reseeding or tree transplanting details. Although it may or may not mean anything
scientifically, I notice that the Alamosa creekbed's rocks have a much less "rusty" surface
coloration near my house than they ever did during SMC's last four years. Thanks for your
efforts. Sincerely, Paul Sinder [Letter; dated 9/27/94; address given]
Comment 18;
To Laura Williams: I am writing to voice my concern on the clean-up efforts being taken at
the Summitville Minesite. Mainly, I would like to state that I fully support the alternatives
researched and proposed to you by the T.A.G. committee. I hope the E.P.A. system is flexible
and the T.A.G. proposals not only be reviewed, but also implemented. I thought the public
74
-------
meeting on October 12th, was very informative and positive. It led me to believe that, although
you have plans made and on paper, you are open to suggestions, criticism and change. The
T.A.G. proposal on water treatment is to my opinion a priority. It will make an immediate
difference in the water quality coming downstream and into our valley. I do hope this will be
realized as soon as possible, it seems common sense. Looking at the T.A.G. proposals, I think
they have found several solutions which promise more lasting and better results (and in some
cases a smaller price tag). A question I have too, is whether the E.C.C has the experience to
tackle the job up there. How many other experts and companies have been approached for
their expertise and advice? I am optimistic that you will find a way of working together with
the T.A.G. team in finding the right solutions. I appreciate the work you are doing and am
keeping my fingers crossed that all goes well I realize it's a tough and very complicated job.
Sincerely Lisa ter Kuile A rural resident surrounded by Terrace irrigated land. [Letter;
undated; no other data given]
Comment 19:
Dear Ms. Williams: We wint to support the recommendations made by the TAG for the
Summitville Minesite. We are concerned here in Conejos County about water quality and the
long term effects of the Summitville Minesite. We want the agricultural community in our
county to remain stable so our role as County Commissioners must look toward the future and
address the long term consequences connected with this site. Please take the TAG
recommendations seriously, the quality of our land and water will determine the future of our
community. Sincerely, Le Roy Velasquez, Chairman Conejos County Commissioners
[Letter; dated October 18,1994; typed on Conejos County Government letterhead]
Comment 20:
Dear Ms. Williams: We, as Board of Directors of the Valle del Sol Community Center in
Capulin, are extremely concerned about the Summitville Minesite and its continuation clean-
up efforts. We are very interested in the quality of our water for our homes as well as for our
farms. We support the enclosure made by the Technical Assistance Grant Committee. We
have showed our interest by making our community center available for meetings so that the
community will continue to be informed and to participate in the process. If there is anything
else we can be doing, please let us know. We are fully aware that the results of the Summitville
Minesite on the quality of our water will determine our livelihood in Capulin. Sincerely, Valle
del Sol Community Center Board of Directors. [Letter; dated October 18, 1994; five
signatures, spelling approximate: Rev. Randy Brennig, Delma Ramirez, James A. Quintana,
Cindy Medina, Julia Gomez-Nuanes; typed on Valle del Sol Community Center letterhead]
Comment 21:
Dear Ms. Williams, After reading the TAG newsletter and listening to Maya ter Kuile, I have
some misgivings about the E.P.A. plans for Summitville. The TAG suggestions surely seem
75
-------
much more reasonable and straight forward than the EPA's approach. Their cost effectiveness
seems much more desirable also. As a new resident to the area I urge you to look again at
what has occurred to the Alamosa River; consider all of us who drink and irrigate in this area
and rethink your approach to what you (i.e. EPA) are doing at Summitville. Thank yon
[Letter; dated 21 Oct 94; unreadable signature; address given]
Comment 22:
Dear Ms. Williams, I am writing yon to voice my support for the Technical Assistance Grant
Committee's response to the EPA's action plan for clean-up of the Summitville Minesite. I
encourage your department to work with the TAG Committee for a thorough clean-up
operation with SLV citizen input Thank you for your consideration - Sincerely, Susan Sawyer
[Letter; undated; address given]
Comment 23:
Dear Ms. Laura Williams, I am writing concerning the Summitville mine clean-up. I attended
and appreciated the meeting on Oct 12, where the EPA presented their progress and future
for clean-up, and the TAG presented their answer and their suggestions on how to improve
the current trend. I have heard and read both sides of the issue. I, as do the residents of this
community, appreciate the work and the concern that the EPA has shown to clean up this
mess. Receiving Superfund status at such a fast rate was excellent We are really grateful to
the organization. My concern, as most of the community's, is the form in which the clean-up
is being performed. Some things were done in obvious haste due to the situation and the
consequences are now being observed Le.: the Reynolds adit plug and the Chandler adit leak.
The best thing to do, I believe, is to sit back and realty assess the situation before any more
mistakes are made. The TAG has gone up there, researched the situation, consulted with
experts and presented a different point of view. I listened to both sides (EPA versus TAG) and
came to the conclusion that the TAG had much better and faster results than the current
method. I was much more comfortable with the research done by the TAG group, seeing that
it was done more in depth and with well experienced experts. The cost, being of great concern
to many, would also be less if you reviewed the TAG group's point of view. There are many
that say that this river has always been polluted. Most of these people do not reside dose to
this river or even in the vicinity. Many live in other counties. I, as many other people in this
community did, fished, not only in this river but also on Terrace Reservoir, not too long ago
(1984-85). This river has not always been polluted. Maybe it's had it's ups and downs, but
it has never been dead. Not only do fish not exist any more but algae can't even grow any
longer. I am stating this because I have heard of people wanting the EPA to pull out, saying
that this river has always been polluted. These people do not know the facts and magnitude
of the damage that can occur and won't see into the future at what will happen to this valley
if nothing is done. I really hope that you really take careful consideration on all our letters,
and take the TAG group's suggestions seriously and implement their ideas. Thank you for
your time and hope you will have another update meeting soon. Sincerely, Nitschka ter Knile
76
-------
and Steven Miller Home and Land Owners, 1/4 mile from Alamosa River. [Letter; dated Oct
20,1994; other data not given]
Comment 24;
Dear Ms. Williams: I have reviewed the TAG committee's recent newsletter and have
discussed the feasibility studies that were done and submitted to the E.P.A. with a TAG
committee member. I would like to comment First, I would like to tell you that our farm has
been in our family for five generations. It is irrigated with water from the Alamosa river
which flows through our farm. My husband and I worked for over forty years to purchase
various parcels of land to make up what is now the present 435 acres. It would be a severe
financial loss to my family and to the other farm families here to be forced to abandon our
farms should the water quality of the Alamosa become incompatible with safe crop and
livestock production. I feel the TAG committee has done an excellent job in their feasibility
study and in the suggestions they have made. I urge the E.P.A. to consider water treatment
to become a top priority and to take the TAG committee's suggestion to build a water
treatment plant at the bottom of the Minesite, rather than to continue with the current
treatment plan, which is not only more costly, but would delay the treatment of the water in
time to prevent damage to thousands of acres of farmland. Sincerely yours, Leola T. Miller
[Letter; dated October 20,1994; address given]
EPA RESPONSE TO WRITTEN COMMENTS RECEIVED FROM
CITIZENS AT LARGE OF THE SAN LUIS VALLEY
EPA will address citizen written comments in one response. All but one of the citizen comments
expressed direct concern with water quality issues as related to water quality conditions in the
Alamosa River resulting from mining activities at the Summitville Mine. Many citizen
comments received expressed support for the TAG committees' recommendations, particularly
regarding the location of the existing on-site Water Treatment Plant and associated costs.
EPA appreciates the fact that citizens have taken the time to attend the public meetings and
review the proposed plans and recommendations. EPA feels that citizen input is a component of
the decision making process and the concerns raised regarding water quality are valid and
deserve consideration. EPA further recognizes the time and effort expended by the TAG to
evaluate the proposed plans and develop constructive recommendations. As with citizen
involvement, EPA realizes that impartial technical assistance provides value in the decision
making process.
EPA is also cognizant of water quality issues which are central to human health, agricultural
impacts, and activities related to fishing, recreational or otherwise. EPA agrees with citizen
concerns especially as they relate to water quality.
77
-------
It is the intent of EPA to integrate recommendations made by the TAG into the final
consideration of alternatives. These may be especially pertinent to specific elements of the Site
Reclamation options. In a letter from the Forest Supervisor of the San Juan/Rio Grande National
Forest dated October 17,1994, the Forest Service expressed agreement-m-principle with the
preferred alternative #4 for site reclamation, stating that "it certainly seems to be the most
reasonable and cost effective in terms of restoring the area to a productive capacity".
The letter also stipulates that, pursuant to the current Master MOU (Memorandum of
Understanding) between EPA and the USDA Forest Service, the Forest Service agreed to
"provide expertise related to natural resource management and protection...". In response to the
proposed plan for site reclamation, the Forest Service has offered expertise, "particularly in the
area of soil/surface reclamation", based upon its "considerable experience in conducting high
elevation reclamation". EPA feels that recommendations made by the Forest Service are
valuable and will be carefully considered in final selection of specific elements of the
reclamation plan, particularly those relevant to revegetation.
Regarding the alternatives for water treatment, EPA recognizes TAG concerns in discriminating
between Alternative 5 and Alternative 6 and TAG suggested modifications to Alternative 6.
EPA further recognizes similarities between the two alternatives. EPA acknowledges TAG
efforts in acquiring cost estimates from potential vendors. Relevant to costs for constructing a
new water treatment facility, EPA is cognizant of potential difficulties associated with acquiring
broad-based cost estimates from potential vendors who may or may not be as familiar with site-
specific conditions. Site specific conditions can dramatically affect proposed costs regardless of
the experience and intentions of potential constructors. However, EPA will take TAG
recommendations under advisement and continue to seek comment from TAG members.
78
-------
2.4 Summary and Response to ARARs Comments
Comment 1;
Another commenter questioned the elimination of biomass and ultrafiltration alternatives
from further elevation in the WITTS and IROD. The commenter argued that these
alternatives should not be eliminated from consideration because, without establishing
ARARs, EPA cannot be certain that "further contaminant removal may not be
warranted." Similarly, electroplating is eliminated for detailed alternative analysis since
the "currently used technology does not produce a concentrated liquid waste stream." The
commenter argues that the WITTS should have considered the possibility of modifying
current treatment processes so there would be a concentrated waste stream acceptable for
electroplating and metals recovery.
Response:
EPA established the site-wide ARARs that must be met in the ARARs Addendum to the
HLPFFS. EPA incorporated these ARARs by reference to the WTFFS as well. While
EPA agrees that this approach may have confused the commenters on the federal and
state law requirements and regulations (or portions thereof) that were applicable or
relevant and appropriate to the various IRODs, each IROD now contains a separate and
complete discussion of the ARARs that must be met by the interim remedial action
selected.
Since the sitewide ARARs had already been identified in the "ARARs Addendum to the
HLP Focused Feasibility Study Report", this further refinement of ARARs as they relate
to each of the IRODs represents only a minor change to each FFS and Proposed Plan.
Consistent with its "Interim Final Guidance on Preparing Superfund Decision
Documents", OSWER Directive 9355.3-02 (June 1989), EPA has determined that this
minor change will have little or no impact on the overall scope, performance, or cost of
each alternative as originally presented in each FFS or Proposed Plan.
The commenter should also note that EPA may eliminate interim alternatives on the basis
of cost if other interim action alternatives are effective and satisfy the interim objectives
and goals. EPA eliminated the biomass, ultrafiltration, and electroplating alternatives on
the basis that the cost were grossly excessive when compared to their overall
effectiveness. See 40 C.F.R s 430(e)(7)(iii) and "Guidance on Feasibility Studies Under
CERCLA," EPA 540/G-85/003 (June 1985).
Comment 2:
In reviewing the HLP FFS, one commenter noted that Alternative 5-3 states that the
cyanide concentrations in solution effluents can be reduced to below 100 ug/L The
79
-------
commenter noted that although the HLP FFS identifies the chemical specific ARAJRs for
surface water as standards promulgated for segment 3b of the Alamosa River, there is no
discussion on how cyanide concentrations from the HLP will be reduced to meet this
ARAR. The commenter requests that EPA provide the calculations which support EPA's .
conclusion that the cyanide concentration will be diluted by flows from Wightman Fork
and the Alamosa River in order to meet the chemical specific, stream classification ARAR.
Response:
The chemical specific ARARs are the basis for the cyanide concentration/dilution
calculations. The calculations serve to quantify the assimilative capacity of Wightman
Fork and the Alamosa River at differing flows. The basis for these calculations and EPA
determination that the interim remedial actions will attain the chemical specific ARARs,
including those for cyanide, is discussed further in the ARARs section of the HLP IROD.
Comments:
A number of commenters noted that the ground water ARARs are also poorly defined,
causing EPA difficulty in determining whether groundwater ARARs can be met by EPA
remedial activities. These commenters challenged EPA's adoption of surface water quality
standards for ground water resources, citing a lack of data. Commenters noted the fact
that surface water consists of snow melt and storm water runoff, plus baseflow
contributions from ground water sources. The commenter argued the Site has historically
exhibited high total dissolved solids (TDS) in the ground water and that EPA has not
adequately characterized other background water quality conditions. Water quality data
from surface water sources typically shows less TDS than from ground water tributary
sources. The commenter believes EPA has failed to account for this data in selecting
ground water quality standards.
Response:
EPA has determined that the classification system-prescribed by the Colorado Ground
Water. Standards is applicable or relevant and appropriate to assignment of standards to
groundwater at Superrund sites within Colorado. Since the Colorado Water Quality
Commission has yet to classify the Sitewide ground water, numeric ground water.
standards are not currently applicable or relevant and appropriate to ground water quality
at the Site. The interim ground water narrative standard adopted by the Colorado Water
Quality Control Commission on July 29,1994, however, is applicable to the Site. This
standard, which became effective on August 30,1994, requires that the ambient water
quality as of January 31,1994, continues to be met This ARAR will be met by
compliance with EPA's interim action levels and with all surface water quality ARARs,
as discussed in each of the IRODs.
EPA, like the commenter, moreover, recognizes the hydrological interconnection between
the surface and ground water flows at the Site, particularly during baseflow periods. EPA
80
-------
expects, therefore, that once the CWQC completes its use attainability study and
classifies Site ground water, this classification will be applicable to the Site. This ARAR
will be attained by the final remedial action(s) for the Site.
Comment 4:
Two commenters objected to the use of RCRA Subtitle C performance standards and
design criteria for containment of existing waste rock, spent ore, and tailings at the Site,
Response:
While EPA agrees that RCRA Subtitle C requirements are not applicable to "Bevill
exempt" wastes, i.e.. those from the "extraction, beneficiation, and processing of ores and
minerals," EPA has determined that RCRA Subtitle C requirements may be relevant and
appropriate to actions at CERCLA mining sites if the mine waste materials are
sufficiently similar to RCRA hazardous waste, particularly if the subject wastes fail the
Toxicity Characteristics Leachibility Procedure (TCLP) or exhibit other characteristics of
RCRA hazardous wastes (e.g.. low pH). See, "Superfund Guide to RCRA Management
Requirements for Mineral Processing Wastes, 2nd Edition," OERR Directive 9347.3a-12
(August 1991). Further, if the disposal activity involves the use of a waste management
unit sufficiently similar to a RCRA regulated unit, and the unit is to receive wastes
sufficiently similar to RCRA hazardous wastes, the RCRA Subtitle C requirements
pertaining to that type of waste management unit would be relevant and appropriate.
(See 55 Fed. Reg. 87630.)
The portions of the RCRA Subtitle C performance standards and design criteria that are
relevant and appropriate to EPA's interim remedial actions at the Summitville site are
identified in the CWP, HLP and Reclamation IRODs.
Comment 5; .
Commenters question EPA's use of the most stringent stream classification - that of
Segment 3b of the Alampsa River - as the controlling surface water and ground water
quality ARAR. They state EPA has adequately explained why it has selected this stream
classification as the "controlling" standard. Further, commenters argue that the numeric
criteria based on the most stringent stream classification does not account for the lower
classifications of other stream segments or for high background levels of copper, zinc and
other hazardous substances in the Wightman Fork and Alamosa River which are the result
of naturally occurring oxidation and transport processes acting upon highly mineralized,
unmined and unprocessed rock in the area. EPA, they opine, cannot remediate water
quality below naturally-occurring background levels. Lastly, commenters argue that the
State erred in designating Segment 3b of the Alamosa River as Class 1 Cold Water Aquatic
Life, and that this standard can never be attained because of background levels of metals.
They suggest that EPA waive this flawed classification based on the technical
81
-------
impracticability of achieving these water quality standards and the State's failure to
consistently apply them, as evidenced by the creation of NCLs in the permit and 1991
Settlement Agreement
Response:
First, the commenters should understand that despite a Class 2 designation in Terrace
Reservoir (Segment 8), Segment 8 carries hardness-based TVS as the ambient standards.
Because the hardness in the Alamosa River decreases with increasing distance from the
water treatment plant at the Summitville Site, the ambient water quality standards in
Terrace Reservoir (Class 2) are more stringent than those assigned to Segment 3b (Class
D-
The commenters should also note that the CWQCC originally proposed to upgrade
Terrace Reservoir to Cold Water Aquatic Life Class 1 but declined because of limited
data. In fact, review of Exhibit 12 to November 1,1993 hearing held by the CWQCC in
Alamosa, reveals the intention to collect needed data and review suitability for upgrade to
a Class 1 designation. As stated in the HLPFFS, at this time EPA believes that
employing the Segment 3b standards will contribute to attaining Class 1 uses in Terrace
Reservoir and should contribute to attaining the existing, more stringent, hardness-based
TVS assigned to Terrace Reservoir.
As the commenter is aware, the re-evaluation of water quality standards in Colorado
streams, rivers and reservoirs is an ongoing process controlled by the Colorado Water
Quality Control Commission (CWQCC). In its discussion, EPA specifically recognized
the inconsistencies and concluded that the Colorado Water Quality Standards (CWQs) for
Segment 3b of the Alamosa River, as the applicable ARARs, will serve as the numeric
interim remedial action goals for the Site.
At this time EPA does not have a basis for usurping the CWQCC authority to determine
appropriate classification and water quality standards for the Alamosa River and its
tributaries. As additional data is gathered and the effects of the interim actions are
quantified, it is within the CWQCC's authority to address all of the issues identified in
these comments. Until that time, EPA will use the existing standards as numerical goals
for the remediation.
In the HLPFFS, EPA made its intention to attain surface and ground water quality
ARARs at Segment 3b of the Alamosa River clear. The attainment of the ARAR for
Segment 3b will be monitored using a "bubble" approach at the downgradient boundary
of the Site, monitoring point 5.5 hi the Wightman Fork (WF 5.5). In this way, no single
interim remedial action alone is expected to bear the burden of ARARs attainment
Where the action-specific ARARs associated with interim remedial actions at the
Summitville Site require identification of an ambient-water-quality-based-end point (L&.
82
-------
NPDES point source permitting), the applicable CWQSs for Segment 3b are established
using a model to back calculate compliance at WF 5.5. This modeling resulted in EPA's
establishment of interim action levels (lALs).
As noted hi the HLPFFS, given the active interchange typical of alluvial ground water
and surface water in high mountain valleys, EPA has determined that attaining
compliance with surface water quality ARARs and the ground water interim narrative
standard will protect both surface and ground waters. This interchange will only compel
groundwater cleanup to the extent required, hi combination with other actions, to qtftMn
ARARs at the point of compliance (WF 5.5) and thereby meet the standards established
for Segment 3b.
The commenter should also be aware that the background concentrations of metals and
acids have been considered. At the triennial review of the Rio Grande Basin the
Colorado Water Quality Control Commission (CWQCC) did recognize that background
metals concentrations hi Segment 3a can be attributed to natural acid mine drainage from
Iron, Alum and Bitter Creeks. Consistent with those findings, the CWQCC promulgated
standards in Segment 3b which reflect the elevated background concentrations and the
wider pH range documented in Segment 3a, EPA believes it has made its reliance on the
CWQCC's work very apparent in the table on page 3-6 of HLPFFS (see the values for
chronic copper and chronic iron).
EPA did not participate in the development of the NCLs. These negotiated numbers are
not duly promulgated and they are not the result of applying site specific data to duly
promulgated NPDES requirements (Le. mass balance, low flow, etc.) to establish a
discharge limit The NCLs may indicate the appropriateness of a waiver at some time in
the future, but at the present EPA will reserve judgement on the use of and scope of
waivers.
The EPA believes that, as an objective, the protection of the Alamosa River as habitat for
a diverse range of cold water aquatic life is appropriate until the combined effects of the
interim actions come into effect Although it is impossible to precisely quantify, EPA
believes that when the combined, beneficial effects of the IRODs are realized, ARARs
will be attained in Segment 3b of the Alamosa River.
At that time, EPA will be able to better quantify the results and determine if additional
action or waiver is required. Likewise, the CWQCC will have another opportunity in
three years to evaluate the results of the interim RODs and use its own use attainability
authorities and ground water site-specific classifications to adjust standards accordingly.
83
-------
2.5 Summary and Response to Reynolds and Chandler Adit Questions
Although the Reynolds and Chandler Adit system is not a part of the current focused feasibility
studies, EPA recognizes the actual and potential contribution that this system may provide to
overall AMD contamination at the Site. Of the four FFSs, the Adit system is of most importance
to the Cropsy action since it is known that precipitation - approximately 72 million gallons per
year - and ground water were funneled by the Mine Pits into the historic underground workings.
The Adits previously drained this water (now ground water) from the mine workings which are
interspersed throughout the sulfide ore body. Contact with the sulfide ore resulted in the
transformation of the natural precipitation/ground water into AMD. This AMD then exited the
Reynolds Adit and flowed into the Wightman Fork stream.
As part of ongoing emergency activities, it was determined that the continual generation of AMD
from the Reynolds Adit could be substantially reduced by plugging the Adit system. (See
Attachment F to Summitville Action Memorandum #2 dated January 28,1993.) This would
result in the re-establishment of the historic ground water table, thereby eliminating oxygen from
the mine workings/Adits. Concurrent evaluation of alternatives to address the Cropsy Waste Pile
included moving the CWP to the Mine Pits from which it was originally excavated. Overall
evaluation of the two actions (Reynolds and CWP) strongly favored the filling and capping of the
Mine Pits to prevent water infiltration through the sulfide ore body.
If the evaluation of the two actions had been unfavorable, it is likely that the Mine Pits would
have needed to be regraded and a drainage notch constructed to reclaim the area. The movement
of the waste piles to the Mine Pits, therefore, has actually resulted in a cost savings overall since
the CWP remedy meets the needs of both portions of the Site. In addition, the reduction in
volume of AMD generated by CWP and the Adits system will result in the decrease of Water
Treatment required at the Site and, therefore, costs for this third action. Evaluation of the Adit
plugs and the re-establishment of the ground water table is ongoing and the information
developed will be incorporated into RI/FS documents to support a separate Reynolds Adit/South
Mountain ground water ROD. .
The evaluation of the two actions was discussed in Attachment F of Action Memorandum #2 and
section 5.0 of the EE/CA for the Cropsy Waste Pile, et al. An interim project report on the
Reynolds and Chandler Adit plugs was released on October 12,1994. Each of these documents
is included as part of the Summitville Administrative Record and is available to the public.
Comment 1:
The discussion in all the FFSs regarding AMD concentrations/ volumes attributed to
various sources should have provided a detailed analysis of the chemical mass balances
associated with water quality in and adjacent to the property [Summitville Site].
84
-------
Response:
As Tables 1-4 of the FFSs plainly demonstrate, there is not a steady release of chemicals
over time with which to develop chemical mass balances. The bulk of the contaminants
are released during periods of high surface water flow such as spring snowmelt or large
storm events. As discussed in section 1.3.2.3 of the FFSs, such an attempt is further
complicated by the varying nature of the geologic features encountered at the Site. To
attempt to develop a chemical mass balance for each chemical and geologic feature for
the various time frames does not add any greater understanding of the risks presented by
the Site.
Coininent2i
There is concern associated with backfilling of the Mine Pits (with CWP, SDI, and HMD
waste materials) since the data suggest that the Mine Pits and the Reynolds Adit are
hydraulicalry interconnected. Because of this hydrogeological connection, a greater
understanding regarding the geochemical interrelationship should have been undertaken
prior to commencing backfilling activities.
The combined impacts of implementing these two actions is still unaddressed, despite the
fact that the combined efforts could well be the reason that another or other alternatives
would be preferred.
Response:
. EPA agrees that the hydraulic interconnection between the Mine Pits and the Reynolds
Adit is an area which bears special attention. If the ground water table - as a result of the
Adit plugging - were to rise above the level of the Mine Pits, then the relocated waste
piles could be subjected to a varying saturated condition. Because of this concern, EPA
placed a continuous three-foot (finished thickness), highly-impermeable clay liner on the
bottom and all sides of the Mine Pits. Placement and subsequent compaction by normal
construction traffic of the waste piles appear to have resulted in impermeable waste piles.
As a result, it is EPA's assessment that saturation of the relocated waste piles is unlikely
to occur as a result of infiltration by the ground water table.
A final cap over the Mine Pits is intended to divert surface infiltration so that saturation
of the piles does not occur as a result of precipitation events. The cap also serves to
eliminate oxygen, which is required for AMD generation, from entering the waste piles.
As a precautionary measure, a continuous five-foot layer of lime kiln dust was placed
over the clay liner for both the North and South Mine Pits (approximately 1,800 tons of
lime kiln dust). The lime kiln dust is intended to neutralize any AMD generated as a
result of moisture present within the waste piles as they are excavated and placed, and
AMD generated by precipitation events occurring during construction. In addition, any
85
-------
surface water infiltration which may occur through the interim caps over the winters of
1993 and 1994 will also be neutralized.
Should the waste piles become saturated despite the design and construction safeguards
described above, any AMD generation within the Mine Pits would take place under
saturated conditions in a high pH environment (high pH as a result of dissolving the lime
kiln dust). As with the ore body, this saturation would result in the elimination of oxygen
from the waste piles. This lack of oxygen would prevent the generation of AMD. While
a more detailed geochemical discussion may be useful for actual design considerations, it
can generally be understood that the suifide ore body below the Mine Pits presents the
highest AMD generating potential for the entire Site. If saturated conditions can
the AMD reaction for the suifide ore body, then the same conditions will also
minimize AMD reaction within the lesser sulfide-containing waste materials.
Comment 3:
This section [1.4.13 of the CWP FFS] indicated that the Reynolds and Chandler Adits have
been plugged, but that the long term effects of plugging the Reynolds Adit and Chandler
Adit, and the consequent rise in the South Mountain water table have not been determined.
EPA indicated in its response to comments on the EE/CA that a state-of-the-art
groundwater flow model that accounts for flow in fractures is being developed in order to
perform such evaluations. However, the Reynolds Adit was plugged prior to completion of
such a groundwater flow model evaluation and any publication of results of such
evaluations.
Response:
The intent of the "long term effects" statement was to convey that EPA does not
definitively know me actual long-term effects which the plugging will achieve since
plugging was only recently completed in March 1994. However, the referenced model
has been able to provide an approximation of the resultant ground water table. At mis
time, a report on the findings of this model is in the final stages of review prior to its
release to the public.
The development of the model was never expected to be completed prior to commencing
plugging activities. Tr^^d. it was anticipated that the model would be used to study the
effects of changes in site conditions (i.e., removal/remedial actions) on the ground water
and Adit system. The model has only recently achieved a relative level of accuracy and is
now being evaluated based upon actual field conditions. Because the Adit pluggings
were conducted as a time-critical, removal action, no formal public review process was
required, though the alternatives analysis for the Reynolds Adit has been a part of the
public record since January 28,1993.
86
-------
Comment 4;
Plugging of the Reynolds Adit should have been evaluated as a long-term solution at the
Site rather than an Interim Remedial Action (ERA). Plugging of the Reynolds Adit could
cause the following: (1) increase of the water table into the Mine Pits, (2) groundwater to
exit the mountain via another shaft or adit (as was the case with the Chandler Adit), and/or
(3) the creation of additional point sources of Acid Rock Drainage (ARD) through seeps.
Response:
As discussed previously, the Reynolds and Chandler Adits were plugged as a tune-
critical, emergency removal action. However, this does not imply that the plugging of the
Adits is considered to be interim in nature. After initial consideration by EPA of the
three potential effects as listed by the commenter, EPA felt it best to evaluate the impacts
to the ground water table and the actual performance of the plugs as a whole system. As
more about the South Mountain ground water regime is known, then a fifal decision
regarding the regime can be developed for long-term considerations.
Comment 5;
EPA apparently has not performed adequate groundwater investigations to evaluate the
short- and long-term effects of the Reynolds Adit plugging. Because of the complexity of
the groundwater flow system at the Site, as related to fracture flow and the hydrogeologic
significance of the mine workings and adits, a groundwater flow model is necessary to
evaluate rises in the groundwater table and the potential for significant groundwater
discharges through existing adits and shafts. Such modeling efforts must take into account
the effects of fractures on groundwater flow characteristics, groundwater recharge
primarily through the Mine Pits before and after filling and capping, groundwater
discharge seeps, and other significant hydrogeologic boundary conditions such as the
underground workings.
Response:
EPA agrees that the South Mountain ground water regime is complex in nature and can
have significant impacts upon the various actions discussed for the Site. As a result, EPA
has directed the development of a state-of-the-art, three-dimensional model with
assistance from the Office of Surface Mining. Each of the parameters identified by the
commenter and other considerations have been incorporated into development of the
model. The model has only recently achieved a relative level of accuracy and is now
being evaluated based upon actual field conditions. It is anticipated that the model can be
developed into a predictive tool for evaluating future actions to be taken at the site.
87
-------
Comment 6;
As anticipated by individuals commenting on the EE/CA, plugging of the Reynolds Adit in
February 1994 apparently caused discharge of groundwater through the existing Chandler
Adit thus providing another source of ARD. As a result, EPA plugged the Chandler Adit
in March 1994. Shortly thereafter, the plug began leakmg low pH metals-laden waters. An
explanation for the failure of the Chandler Adit plug is not discussed in the FFS. Failure of
the plug could be primarily a result of one or both of the following flaws in establishing the
plug design parameters: 1) failure to use conservative hydraulic parameters, such as using
the maximum possible hydrostatic head expected at the plug that would result from
plugging of the Reynolds Adit; and 2) failure to select suitable competent rock for keying
the plug. This section also mentions that corrective measures are planned for the Chandler
Adit, however, no specific discussion of the nature of the contemplated corrective measures
is provided.
Response:
Concerns regarding potential discharge from the Chandler Adit once the Reynolds Adit
was plugged did result in EPA including plugging of the Chandler Adit as part of the
removal action. However, the work for both Adits was conducted in a concurrent fashion
and was not based upon actual discharge observed from the Chandler. The Chandler did
not fail until May 23,1994, which is a sufficient amount of time after construction for the
plug to have been fully effective.
EPA agrees that the subsequent failure of the Chandler plug is likely to be associated with
the plug design or the surrounding rock conditions. The corrective measures for the
Chandler are not discussed primarily because the plug failure was still being evaluated.
This assessment effort was initiated in November 1994 and it is anticipated that work to
repair or replace the Chandler Adit will be completed by Spring 1995.
Comment?:
EPA should not repeat the same mistake of replugging the Chandler Adit without
performing the appropriate hydrogeologic investigations and evaluations. Replugging the
Chandler Adit may cause, as was the case hi the Reynolds Adit plug, water exiting out of
another adit or shaft or significant hydrostatic pressures in the mountain that would cause
the development of multiple point sources via seeps at the base of the mountain. As
indicated above, the Chandler Adit is presently discharging low pH metals-rich waters
directly into Wightman Fork. It is not known why EPA did not open the valve in the
Reynolds Adit to reduce or preclude flow from exiting the Chandler Adit and treat this in
the PITS facility prior to discharge to Wightman Fork. This demonstrates a failure on
EPA's part to develop an overall environmental strategy at the Site, as opposed to a
number of disconnected and uncoordinated individual actions.
-------
From an emergency response standpoint, it may have been appropriate to keep the
Reynolds Adit open since water from the Reynolds Adit could be readily treated.
Response:
Based upon the short success during the time that the Chandler Adit was functional, it is
unlikely that replugging of the Adit will result in discharges from other adits/shafts. The
ground water model being developed tends to support this conclusion. However, it is
known that historic seeps did exist on South Mountain and it is reasonable to expect that
these seeps would redevelop. Even so, the rationale for plugging the Adit system was to
flood the mine workings and thereby eliminate oxygen from the reaction which generates
AMD. This will result hi the gradual improvement of the South Mountain ground water
and, therefore, the water quality of the seeps.
The design for the Reynolds Adit included two separate plugs with piping between the
plugs. A valve which would allow EPA to dram the water behind the two plugs was to be
installed once the second plug was completed. After observing the better-than-expected
performance from the first plug, EPA determined that a second plug would be a
redundant expenditure and it was eliminated from construction. As a result, the
capability to open the valve - as originally considered - did not exist at the time that the
Chandler began to discharge to the Wightman Fork. This valving capability has since
been installed and EPA has been treating the Chandler discharge at the PITS facility.
Rather than a lack of an overall environmental strategy for the Site, this incident is more
representative of the extreme physical and timing realities presented by the Site. Overall,
discharge from the Chandler Adit produced less flow and less copper concentrations than
experienced from the Reynolds Adit during the same time frame of the previous year.
Comment 8:
Plugging the Reynolds Adit may not, in the long term, reduce acid mine drainage flows and
may turn out to be a very expensive experiment Also, this interim action may actually
exacerbate site problems and, thus conflict with the National Contingency Plan.
Response:
Base upon current data gathering efforts and the recent predictive capability of the ground
water model, EPA has determined that plugging of the Reynolds Adit will result in a
reduction of contaminant transport from the Site. Therefore, these actions will not
exacerbate Site problems or interfere with the final overall site remedy. However, should
monitoring of the South Mountain ground water indicate that the plugging is actually
exacerbating Site conditions, the (now installed) valve within the Reynolds Adit can be
opened and treatment of the water initiated in the PITS.
89
-------
Comment 9;
It is stated that "In 1993 and 1994, Emergency Response Removal Actions (ERRA) were
taken to reduce contaminant load in untreated Site water. This was achieved in part
by~.prevention of AMD flow from underground workings*." Plugging the Reynolds Adit
probably did not reduce the contaminant load in untreated Site water.
If no immediate reduction of contaminated water flows was expected, what was the
rationale for the precipitous action in 1993 and 1994 regarding plugging of the Reynolds
Adit? Alternative actions and consequences of combined actions could have been evaluated
on sound scientific bases thus providing for recommended alternatives with higher
expectations of achievements for interim remedies and final overall site remedies.
Response:
In the spring of 1993, discharge from the Reynolds Adit reached a peak flow of 763
gallons per minute with supersaturated concentrations of copper. Due to treatment
capacity limitations at the PITS facility, approximately 600 gallons per minute of the
discharge overflowed the holding pond and escaped untreated into the ground or
overflowed into the nearby creeks. While this occurred over a limited 3-4 week period,
plugging of the Adits eliminated this highly contaminated discharge to the Alamosa
drainage during the 1994 spring season.
In general, each of the remedies discussed in the FFSs are anticipated to have a gradual
impact upon water quality and cannot be guaranteed to dramatically improve conditions
over a short time frame. Also, because of on-going water treatment, implementation of
the remedies is expected to allow EPA to discontinue water treatment while maintaining
compliance with current water quality standards.
Comment 10;
This section [1.4.4.2 of the CWPFFS] does not provide an adequate description of the
groundwater flow conditions at the Site. A discussion of the prevailing groundwater flow
systems should be provided, including the groundwater flow direction, permeabilities, and
storage coefficients. Also, there is no discussion provided on the regional and local
hydrogeologic boundary conditions at the Site. It is unclear where the recharge and
discharge (seep) areas occur, and the hydrogeologic effect of the underground workings
and their significance as a hydrogeologic boundary conditions are unknown. The text does
not discuss how plugging of the Reynolds Adit will effect the groundwater table conditions
at the Site. If these conditions are unknown, at least a qualitative description is necessary.
The FFS does not include a description of the promised state-of-the-art groundwater flow
model that was supposedly developed to make these necessary evaluations. The model, as
well as information on model assumptions, model hydrogeologic boundary conditions,
should be included in an adequate FFS. The results of such modeling evaluations may
90
-------
significantly alter the conclusions of the FFS with regard to replugging the Chandler Adit
Such simulation would have provided insight into the water table levels which could affect
conclusions regarding the effectiveness of the selected alternative.
In addition, EPA does not provide in the FFS a description of the proposed monitoring to
determine the effectiveness of the plugging in the short- and long-term. Evaluating the
effectiveness of the Reynolds Adit Plug will require monitoring of: (1) fluctuations in the
water table; (2) existing seeps; (3) changes in flow quantity; and (4) changes in water
quality through these seeps. Also, monitoring the development of additional seeps is
critical. Information regarding what EPA is currently considering as baseline for
monitoring and what methods will be used to evaluate the effectiveness of plugging is
necessary to determine the impact of plugging these two adits, particularly with regard to
final site remediation. Further, information on the monitoring efforts currently being
performed by EPA to monitor the potential development of additional seeps as a result of
the Reynolds Adit plug, and the results of such monitoring, are critical to evaluate the
effectiveness of the remedy.
Response:
EPA agrees that inclusion of the ground water model in an FS is essential to evaluating
the effectiveness of a selected alternative for the South Mountain ground water regime.
EPA also agrees that the results of monitoring for the various considerations outlined by
the commenter are essential in assessing the impact of the Adit .system plugging,
particularly with regard to final Site remediation. However, the plugging of the Reynolds
and Chandler Adits and their impact on the ground water are not the focus of any of the
four FFSs provided for public review and inclusion of the suggested information in these
FFSs is therefore inappropriate. Nonetheless, the modeling and monitoring efforts are
actively being pursued and EPA anticipates that this information will be incorporated into
future RI/FS documents to support a separate Reynolds Adit/South Mountain ground
water ROD. These documents will be provided for public review and comment prior to
remedy selection.
91
-------
3.0 REFERENCES
ALL REFERENCE MATERIAL AVAILABLE IN THE EPA ADMINISTRATIVE RECORD
92
-------
Table 1 Copper Content - Site Contaminated Water, 1993-1994 Record
1 993/1 994 ENVIRONMENTAL ANALYSIS-SUMMITVIUE SUPERFUND SITE
COPPER (IBS)
1(993 1(994
SAMPLE MAY JUN JULV AUO 6EPT OCT NOV DEC JAN FE6 MAR APR MAV JUN
LOCATION .
JULV TO JUNE
COPPER LOAD
UBS)
PERCENT OF
CURRENT
LOADING
FRENCH DRAIN SUMP
STRCAM A
VALLEY CENTER DRAIN
FDS-I
DIKE ( SEEP
FDS-2
LPD-1 ft ROAD SEEPS
FDS-3
IPO-4 ft 6 COMBINED
FttfNCH DRAIN SUMP
TOTAL FLOW
HEAP LEACH PAD
STRCAM B
CWP OVERFLOW 1680 DO)
CROPSY WATER
(TREATMENT PLANT)
HIPLEACHATE
(INFLUENT TO COP)
UNDEROROUND WORKINGS
STRfAM C
REYNOLDS ADIT (AD 0)
PITS
(REYNOLDS ADIT TREATMENT)
CHANDLER PORTAL
CROP8V CREEK
LPOI
(EAST OF F. D. SUMP)
STREAM H
CROPSY CHEEK
POND 4
STRCAM F
POND 4 DISCHARGE
IOWA ADIT
663
(.(36
(2
627
3.191
(.121
(.4(6
384
3(4
3.940
831
282
'££.
8)
(.823
622
(81
(8
34
(.6(3
(.888
(98
36
46
899
GB3
(20
. 36
37
629
4(4
(47
22
28
481
4(7
(22
(6
28
482
483
(04
>,- ;\
23
438
409
63
;.-«•• '/
(7
374
361
60
j> 'r.
(6
391
364
37
f f Jf
(39
492
608
632
64
268
2.238
2.160
1.601
302
79
2.4(0
8.679
3.434
463
767
(2.269
PERCENT OF
POTENTIAL
LOADING
2.72%
8.346
39.364
63,242
(2.770
'
2B(
3.624
4.037
37,986
(10,739
16.661
; ,
198
860
791
33.162
34.432
(8.760
,-, ' -
31
(27
333
24.668
20.2(2
(8.472
fit ,','
69
(((
349
y
22,708
(46
21,802
76
18.036
26
V
(8,082
4
(3,673
9.334
2.843
8.047
< -'<;-<'
(.840
7.836
19.272
19.272
* ,
7
26
8.3(9
6.319
''.,-, ^a
0
21
2.663
2.662
jf
\ f '' '
21
(42
94
# ',
f,\
(6
((2
(40
j* ' '•••
Wf,
.»
86
(64
, 5*
%> '
(69
1.191
7.4(1
6. (03
(.484
6.833
8.0(8
0
(1.764
(84
642
(.(28
0
83,788
.268
671
4.379
(8.927
(92.466
(02.679
86.178
86.642
821
(.737
(2.76%
69.63%
(.27%
0
":;..•:;.; ;;?;;:
406
MX*®*
726
:::"&:;';W
323
"&Wr%
78
';sj?;4£;
8
~
•v
'
f
,
>
^ ' ' ff
/, '''
'' '
OTHER CONTRIBUTORS TO WIOHTMAN FORK
STRCAM D
CLEVELAND CLIFFS
STREAM f
NORTH DUMP DRAINAGE
STRfAM 0
CLAY ORE STOCKPILE (SEEP 11
TREATMENT DISCHARGE
TO WIOHTMAN FORK
MONTHLY TOTAL OF
CURRENT CONTRIBUTORS
MONTHLY TOTAL OF ALL
POTENTIAL CONTRIBUTORS
WF-5.S WIOHTMAN tORK
4.436
3.389
2.306
23
64.249
((7.897
47.436
. 3.904
3.466
(.028
46
106.231
(66.680
71.161
(.287
666
'f/:
31
(7.389
72.994
20.64E
(.786
97
-,;
'22
4.480
49.470
8.424
(.626
31
'' ..
28
(.874
46. (73
3.689
873
4
:'
32
(.039
36.93G
030
609
',
< ,;
21
062
27.190
790
644
'', *
''*'/'
13
679
22.674
670
'/
, '-;
(1
33
(6.798
470
,'s.
,t
/ '
0
63
9.866
374
t ' '-
' < •«
^
0
•a
(2.4(7
399
/:?'/'
_,
' *''
0
82
(0.4(2
909
(,OO2
37
1.965
223
468
1.6(3
676
6
10.161
33.080
20.424
6.110
1.810
237
24
84.630
1(4.331
87.460
4.608
HIM
3.29%
(2.294
4.321
(.(13
(99
(37.204
460.266
(43.09J
6.96%
3.16%
0.81%
0.(4%
(00.00%
0.97%
4.20%
42.76%
22.80%
21.22%
0.39%
(.00%
2.73%
0.96%
0.26%
0.04%
(00%
-------
Table 2 Cyanide Content - Site Contaminated Water. 1993-1994 Record
1993/1994 ENVIRONMENTAL AN/
CVANIDE
I
' lAwni .
IOCATMN
FMNCH DAMN 81M4P
StlltAUA
VAlliV CENTER DRAW
fOSI
DIKE 1 SEEP
fOSI
IPO- 1* ROAD SlfPS
fOS-i
IPO-4 ft 1 COMBINED
fHCNCH ORAIN SUHP
limOENTj
HEAP If ACH PAD
SlHtAUg
CWP OVERFIOW (SBO OO)
C«0/>Sr MM DM
•TREATMENT PIANTI
HlfltACIlATf
UNFIUENT TO CDPI
UNDERGROUND WORKMG6
SrflCAMC
REYN0108 ADIT IAD 0)
firs
(REYNOLDS ADIT TREATMENT)
CHANDllR PORtAl
CROPtV CREEK
(«M
(EAST Of P. 0. SUMP)
STREAM H
CflOPSV CREEK
POND 4
SJflCAMF
POND 4 DISCHARGE
DW4 JlO/r
OTHER CONTRI6UTORS TO WOHTMAI
SJtttAMO
CLEVELAND CltfFS
SlRlAMf
NORTH DUMP DRAINAGE
SJfttAUO
CLAY ORE STOCKPILE (SEEP U
M£4 TMCNT OtiCHAHGf
TO WKSHTMAN FORK
MONTHIV TOTA1 OP
CURRENT CONTM6UTOR)
MONTHir TOTAl OF All
POTENTIAL CONIRI1UTORS
Wf-lS WICH1UAH FORK
UYSISSl
911
MAY
4SO
48
1
0
I. Hi
0
34. 1»S
0
0
0
If
0
!**&£•:?:
torn .
i
0
0
163
ISC
38.46
1.61
MMITVIl
JON
642
18
• 12
0
I.IK
0
H.OII
0
0
0
«w
0
'ISWSiiS':
0
0
0
164
ttt
30.41
1.J2I
.E 8UPERF
JUtV .
•it
16
V^x
0
1,01}
0
<
11.16?
0
0
'" f *
0
1
0
•••:5^'«:Sj.:
0
0
r.\t y '
'i •• >
20C
20
26.69
22
JNO SITE
AUO
461
»
' 20
2
I.IM
0
... >>
«/.»>«
0
0
' •"' V
0
n
0
!5?«:::5:i;x'-S:
0
0
*$\3 •'
74
•1
I8.ua
401
6EPT
US
J
0
0
SJ6
0
,' J
•
0
0
- , ..
'/ *
0
'<•'•
J «•• '
%i ' "
'•:' Z" ' '
43
41
16.16S
16«
694
JAN
646
3
'', ;
0
496
0
I3.3H
0
0
" ''
'• ,' ''•
>-. f f f^
0
'' f'' o
: /'
^ > !
0
0
' '
^ f\
1
"< ^
:. >:.- -
1'
^ ^/'
•"X ^
^ ^ '
0
1
•.241
1
MAR
430
1
^
/> i '
0
«<
^^,;.i
jf ff
0
6.S31
0
0
•I- ' ; •* 5
' ''""< f \'
»/- < ;
0
f f
, /.- -
* %••";' '
'*" •?'> J'
^ •• -— f.
,4,^'f
0
i
6.101
I
APfl
608
0
"> 5'
.- v
0
030
' ' •*/
< V
0
1.164
0
0
~*£i;L
• ?'i %"
•-^ .-^ ^
t
•' ''
^ /' '
' •;} t
,*"<•-
"• •• '$
0
1
7.784
22
MAY
681
6
6
0
eta
0
0
S.llt
0
0
0
•',-.•; »•; •
"•$• ' '/
9
0
% x . •:•>'
0
•^ '
< v ', -:
0
36
49
6.619
260
JON
388
14
12
0
486
0
0
6.126
0
O
0
0
7
0
0
0
0
0
in
124
6.616
2,896
JM.Y TO JUNi
CVANIDE 10AD
11*61
1.418
II
102
. 2
7.346
0
0
166.717
0
0
0
0
64
6
NflM
0
0
0
721
784
186.117
4.631
PERCENT OP
CURRENT
tOAOINd
o.oox
0.00*
0.00*
6.86X
1.02%
0.00*
o.oox
001*
12.09*
100.00*
PERCENT Op
POTENTIAL
IOAOINO
4.42%
89.64*
o.oox
o.oox
0.03X
000*
o.oox
o.oox
o.oox
0.43X
too*
-------
Table 3a Site Surface Water and Treatment Plant Flow Rates, 1993-1994 Record
1993/1994 ENVIRONMENTAL ANALYSIS SUMMlTVILlE SUPERFUND SITE
FLOW RATE IQPMI
|1B91 . 11994
fAMPLE MAY JUN JULY AUO SEPT OCT NOV . DEC JAN FEB MAR APR MAY JUN
LOCATION
HIGH FLOW
IUPMI
17(83 TO 6/B4I
LOW FLOW
IOPMI
17/83 TO 6/94)
FRENCH DRAIN SUMP
SJRCAMA
VALl€Y CENTER DRAIN
fDS-t
DIKE 1 SEEP
fOS2
LPO-1 & ROAD SEEPS
FDS3
IPO-4*. 6 COMBINED
FRCNCH DRAIN SUMP
(EFFLUENT}
HEAP LEACH PAD
STRCAMB
CWP OVERFIOW (660 DO)
CRQPSY WATCH
(TREATMENT PLANT)
HIPlfACIIATC .
(INFLUENT TO COP)
UNDERGROUND WORKINGS
STRCAM C
REYNOLDS ADIT (AD 0)
PITS
(REYNOLDS ADIT TREATMENT)
CHANDien PORTAL
68
40
1
26
161
3B4
/'•
6B4
4BB
74
CROPSY CREEK
LPD-2
(EAST OF F. D. SUMP!
STRfAMH
CROPSY CREEK
POND 4
S1RCAM f
POND 4 DISCHARGE
IOWA AWT
26
2.805
- -':
67
29
IS
26
IBO
72
e
'\''/i,r " ,
'"%'**>
14
124
69
B
3
12
103
62
6
3
12
B6
71
3
3
13
70
70
4
3
11
70
74
3
2
10
70
73
1
^?,~, ',
f"'^'.
1
70
70
1
' ;;--' '
./*^,'
6
70
70
1
'''?,',','&
6
70
78
1
'.?.'
6
87
132
14
4
10
1B6
118
. 39
20
13
181
132
38
20
14
166
1SI
; :
723
763
113
28
2.608
768
' 47
-;
677
388
192
IB
,-,i- ,
668
272
218
' -
16
* "* *
847
8
774
4
' "
874
229
237
f "* '
180
180
' , <
119
119
-
2
843
115
, ''
6
327
318
t .<• .-,
2
23B
138
' ,' Y 'f
2
104
33
f jf f f
> ' ,-•* *
''••'*'/:*'
69
4
2
839
97
97
•*
•• x
62
, >.
0
;> '/
'/' <
650
46
89
'
",#
62
'
-r'Vv
•" •"•" /
' '', '»
621
8
67
'
''-; V:
36
S f f
, t '
'"' ,'- '
;; •" > '•
108
848
>, •• ', !
74
881
7
72
f ,
Y,"f"
'•*;, S,*
41
' ' ^
6
86
'. ff *
' 'f"f
,! ',''"";
89
••
28
178
634
0
369
13
1.346
848
20
44
182
760
68
0
671
29
2,460
766
134
47
170
774
398
237
871
28
2.460
848
HIM
69
1
2
6
70
0
74
634
6
0
369
*
36
4
HIM
OTHER CONTRIBUTORS TO WIQHTMAN FORK
STMAMD
CLEVELAND CLIFFS
STRCAM f
NORTH DUMP DRAINAGE
STRCAM 0
CLAY ORE STOCKPILE ISEEPLI
.•>:' .£; '--;-•. .-.'. • :.- •; -• ':"•-.- : '
MONTHLY TOTAL OF
CURRENT CONTRIBUTORS
MONTHLY TOTAL OF ALL
POTENTIAL CONTRIBUTORS
WF-6.6 WIOHTMANfORK
202
2B4
4B
3.762
4.936
16.668
168
282
66
4,440
1,867
13,823
62
87
/•
• f
1.083
2.121
3.363
83
13
f f
• •
786
1.700
2.328
69
4
,"','
, '' ;
440
1.420
1.13
43
2
'
- „ ,
1B2
1.214
696
33
- ;
•<
,>
ioe
873
701
37
- ,
,
-
99
90?
493
f' Sf '
,.'
/ s /•
- A-
;' '
jt _, f
',*
62
816
34'
!',4".-'
z.i , ,
' % . f
* f * f
' s ' '
36
736
23:
''>' ','„','
s
,',
\ '' ''
' 'f", ',
41
874
2B6
• f' *
'. /
, '•.
' ;' "
89
817
1.279
109
254
37
' -j
3.083
3.888
10.483
168
314
41
4.366
6.484
12.626
168
314
41
' ••
4.366
6.484
12.626
33
*
37
,
36
738
233
-------
Table 3b Site Surface Water and Treatment Plant Water Volume
iSJMSM ENVIRONMENTAL ANALYSIS SUMMITVIUE SUKRFUN.D SITE
OW IOALLON8)
HiiriFLOw
(OAllONII
17/61 TP6(64|
LOW FtOW
IOALION6I
11/93 TO 6/841
6AMFLI
LOCATION
JUN'63
JU1V '•!
AIM'*}
3IFT-63 oci-63 NOv-91 MC-II
FWM MAII'M
AM'M
MAVM
JUN'M
INCH PHAIN 8UMP
M&IM4
AlttY CINflR MAIN
1.669.120
2.492.400
I. J 14.080
1.111710
1.1(9.440
1.011.000
1,301.160
1.386.720
1.111,400
1.114.800
1.169.600
(.691.460
(.149.440
(.692.460
2.611.760
01-1
i I tliP
1.715.600
1.162.600
H7.UO
111.100
a 11.000
111.620
I71.BOO
Ill.flO
44.840
40.110
43.200
•14.960
1.837.180
40.110
OS I
PO-I 6 Hoxotttn
44.140
UJ.tlO
I If ,100
111.910
111.800
at. iso
lji.860
146.110
646.110
19.180
OS}
m-4 4 6 COMBINiO
I.HI.OOO
1,080.000
614.660
• 11.180
616.400
660.110
476.100
141.910
211.200
1I6.0OO
446.400
140.000
614.960
216.000
/UNCHCMAIHSUUf
fflUiNII
6.740.640
6.108.OOO
6.611.160
4.697.610
4.104.000
J.114.800
1.014,000
1.114,600
1,124.600
2.621.400
3.114.600
1.7(6.400
6.1B6.400
6.886.200
6.186.400
1.611.400
HtAHtACHfAO
IHtAUt
WP OVtltftOW I860 DPI
16.146.660
6.181.100 ' 1.098.060
601.610
648.OOO
167.120
172.600
69.160
1.149.920
1.916.060
2.096,080
HOPS* WAII*
HiAIMIHT PIANH
4.611,120
3,196.600
7.686.640
6.996.400
7.886.640
1.196.600
16.616.160
11.111.600
10,111,260
26.166.140
27.980.400
14.661.360
28,116:600
26.624.960
29.018.OOO
26.016.710
26.826.710
26.686.200
21.817.760
12.400.000
14.661.180
INflUfNT JO COP)
21,617.760
NDCROHOUND WOIUWOI
TIUAH C
IYNO108 ANT (ACO)
21.686.040
11.961.600
17.766.710
11.141.080 6.691.600 6.038.100 6.14O.600 4.110.090 1.016.884 161.660 308.011 244.080
2.496.960
17.766.710
144.060
Hit
BIYMOiOlAOITTMATMtNTI
1.101.160
6.670.860
9.711,610
10.136.400
6.019.100
6.140.600
4.310.080
1.010.160
2.701.440
3.214,080
1.716.100
10.118.400
16.472.160 24.664.240
norty CMIK
pot
IIA6TOM.0.6UMM
1,160.640
1.209.600 ' 89.260
223,300
66.400
89.260
660.120
1.2(2.600
1.282.600
66.400
S1MAI4H
CHOPSY CREiK
126.116.100
101.146.600 11.701.810
14.197.160
10.114.600
4,642.660
3.660.600
1.767,660
1.111,160
1,461.610
1.610.240
1.644.600
60.069.440
106.631.160
106.611.180
1.4(1.611
itRtAUf
OHO 4 OISCHABOI
11.091.100 1.111.600
1.471.120
42.1I6.710I 13.OB9.600l
41.116.720
OTHIB COMTIUIUYOB6 TO WMHTMAN fOM
Hll
1RIAMO
OtVtlANO Cilffl
6.017.260
7.267.600
2.111.260
1.706.110
1.646.800
1.8H.610
1.426.600
1.691.680
4.666.760
7.246.604
7.246.804
1.416.600
1RIAMI
MOUTH DUMP OHAINAOf
12.677.760
11.162.400
2.990.660
660.120
171,600
66.960
11.316.660
11.664.800
11.664.600
SJRtAUO
2.167.180
1.661.200
1.781.910
1.661,68
MONTHtV TOTAL OF
CUBHINT CONtBUUTOM
167.489.390
191.808.000
46.146.120
18.488.800
19,006,000
6.101.160
4,679.200
4.419.160
1.121,280
1.461.620
1.610.240
1.644.600
116.712.120
166.616.164
168.616.184
1.491.620
MONTHLY TOTAL OF AIL
POTENTIAL CONTHI8UTOH1
120.196.400
244.161.400
94.770.720
76.666.000
61.601.200
64.110.640
41.011.600
40.468.460
16.487.664
19.676,620
19.006.412
39.64S.260
177.916.040
118.666.064
216.868.064
29.676.610
694.609.120
666.611.600
146.677.910
101.611.820
46.666.200
31.002,460
30.686.600
22.007.620
16.1(6.160
9.394.660
13.166.600
68,262.600
467.66I.MO
641,108,810
141.108.910
9.194.660
-------
Table 4
Contaminant Content at High and Low Flows -
Identified AMD Streams
Snraoii .'/.:: ""'.'.';'•
RecordiDpDtte- .- • :
High Flow
Low Flow
Gm-:^rf^ ;-•••:
High
Low
.VfangmesesIojtaK^ J.-p;!
Recovetabte^^Sr. r^
High
Low
Tmfr .T1>- .'•*!5C!::'-idt>'S^' •}'.•-;
JroowlJC- -.T^fVii^S^-^t •• -"
High
Low
rotatCyaaidet-iJirg.i"*-... ._•;.••• •
High Flow
Low Flow
Stream A
1^08^3
9/0&93
^ •; ".: .-;:
74.4
62.1
;/;v • .;• '.-V1 V^
:^i-" 'VJ'^'-'-V?'
56.6
23.61
?•;'-.- r:.-.1.-^:-^?
297.6
438.1
ri:;;1-;:^;:.;-^
25^5
10.95
Scrams
5/24/93
12/16/93
!'. ~^' •' ' •=':
597^
1
?:^'--. .;:^
t:*i"-.-^:.:
72
S3J4
r^y^r.
1240
793
;:::;S:'.i:;. •;".';
NR
NR
StrcanrC
6/10/93
5/13A>3
.. .f..
910
74
rrV^.;"- ....
:;*-i- .,.--_.••
35^
15.4
jf.'5i:"v ?.--.-••.
—'^i--ii-^*-,i"-::r-"
1738
368.4
;:A;''.:~ - ,
NR
NR
Stream 0
6/02/93
11/05/93
.• 'v'.^J ' " ;
348
19
- . '-. — ;-.~ii-' • ....
72
66.09
636
310.8
••".'• ; '.
OJ)17
<-01
. Stream E
-.••..": •
6/08/93
9/21/93
r--t*ff.^-- .'••-.
S^&BSji'-'r . '
283
1
i&SI;:' i;si
J^'i***?^ ' •->.
40
16.6
*• •'— — • •— ^__ •
^••fc^i.^ltyi1 •' -':-• ;
«\-;?rSr'~' '-
447J
76J8
^.iTti'-jtC"''*" - • •
NR
NR
' Streant F
6/02/93
6/10/93
,.;'•;.; ./ -V;
105
24
t^"V '"• - ""— • *
,«^.' ; *".,.. .^T. ; -
•t&gF'-'.-rr'.v.^'.'r
55J
54.75
^vfKSi^
2157.1
SOO
•r;?-.-;..^-;;;...-.;
<01
<.01
StreaofG^
'•"•:S
.6715^3
11/17/93 ||
; ;?^|
1176
Oo
10
65o3
r-^i
109^5
26^1
.. /r.-r.V.SgK
•• "' /•"•.rrt
<-01 JJ
<01 ||
Aluminum and Zinc Content at High and Low Flows •
Identified AMD Streams
Stream:- ••"—•$?.'• *i£*:5"' ••' •'-
ReeonKaySJuter:-^'-:. .••"
High Flow
Low Flow
Zinc digested* ••••••••,'
High
Low
Aluminum-, dig;
High
Low
Stream* A.
2/25/94
15.98
43
StreamC
:•: •.•.'••••.,:
6/22/94
5/01/94
101
64.1
1644
%7J
Stream B-
•j!jf . • .•;
6/20794
s/03/94
9.73
4.99
154.5
60.78
StreantE
'-•' •
:. Stream*
.:/>
; Stream: C
;;••> .-.;_•
Stream tt
No information Available
•: FDtEjj
. • '.-:---jS»
•--^*^r
6^L94
•'•?*?
105
' '•-•*•
993.1
All concentrations - mg/l
NR - Not Recorded
-------
Table 5
COPPER CONCENTRATIONS AT WF-5.5
I I I I I I-I- M- f
--I-HH-H-J
H-t- I I I I -i t-l-l-l I l I l l
6- 24- 15- 2- 21- 4-
24- 8- 29- 13- 29- 11- 23- 7- 29- 14- 5- 16- 16- 6- 24- 15- 2- 21- 4- 2- 23- 20-
May- Jun- Jun- Jul- Jul- Aug- Aug- Sep- Sep- Ocl- Nov- Nov- Dec- Jan- Jan- Feb- Mar- Mar- Apr- May- May- Jun-
93 93 93 93 93 93 93 93 93 93 93 93 93 94 94 94 94 94 94 94 94 94
Date
-------
Table 6
TOTAL CYANIDE CONCENTRATIONS AT WF-6.6
24- 8-
May- Jun-
93 93
29- 13- 29- II- 23- 7- 29- 14- 5- 16- 16- 6- 24- 15- 2- 21- 4- 2- 23-
Jun- Jul- Jul- Aug- Aug- Sep- Sep- Oct- Nov- Nov- Dec- Jan- Jan- peb- Mar- Mar- Apr- May- May-
93 93 93 93 93 93 93 93 93 93 93 94 94 94 94 94 94 94 94
20-
Jun-
94
Date
-------
Table 7
Potential Chemical Specific ARARs
Standards, Requirements,
Criteria. Limitations
OROIJNDWATER:
National Primary Drinking Water
Standards
National Secondary Drinking
Water Standards
Maximum Contaminant Level
Goals
Colorado Ground Water
Standards
Citation
40 C.F.R. Part 141. Subpart D
pursuant to 42 U.S.C. §§ 300g-l
and 300J-9.
Slate: 3CCR 1003-1 pursuant to
C.R.S.§25-M07(lXx)
40 C.F.R. Part 143, pursuant to
42 U.S.C. §§ 300g-l(c) and 300J-
9
40 C.F.R. Part 141. Subpart F,
pursuant to 42 U.S.C. § 300g-l
State: 5 OCR 1002-8
3.11.8
3.110
Description
Establishes numeric standards
for public water systems.
Maximum contaminant levels
(MCLs) are established to
protect human life-time drinking
water exposure.
Establishes aesthetics-related
standards for public water
systems (secondary maximum
contaminant level).
Establishes drinking water
quality goals set at levels of no
known or anticipated adverse
health effects, with an adequate
margin of safety.
Establishes a scheme for
identifying groundwater
specified areas, for classification
of Colorado ground water and
provides numeric standards.
Also, establishes an interim
narrative standard for all
unclassified ground water,
supplementing statewide
standards.
Potentially Applicable or
Relevant and Annronrlate
No
No
No
Applicable
Comment
No public water supplies
are present, the Slate of
Colorado has
comprehensive ground-
water classification system,
including numeric standards
equivalent to (MCLs). See
section 3.2.1.
Protects aesthetic character,
not relevant to protection of
human health or
environment.
No non-zero MCLGs set at
levels less than MCLs were
identified for contaminants
of concern.
See section 3.2.1.
-------
Table 7 (continued)
Potential Action Specific ARAHs
Potentially Applicable or
Rftovnilt anil Appropriate
Wild and Scenic Rivers Act
Executive Order on Protection of
Wetlands
Executive Order on Floodplain
Management
Rivers and I (arbors Act of 1899,
Section 10 Permit
citation
I6U.S.C. §§ 1271-1287
40 C.F.R. § 6.302(e)
36 C.F.R. Part 297
Exec. Order No. 11,990
40 C.F.R. § 6.302(b) and
• Appendix A
Exec. Order No. 11,988
40 C.F.R. § 6.302(b) and
Appendix A
33 U.S.C. § 403
33 C.F.R. Parts 320-330
Description
Establishes requirements
applicable to water resource
development projects affecting
wild, scenic, or recreational
rivers within or studied for
inclusion in the National Wild
and Scenic Rivers System.
Requires federal agencies to
evaluate the potential effects of
actions they may lake in
wetlands to minimize adverse
impacts to the wetlands.
Requires federal agencies to
evaluate the potential effects of
actions they may take in a
floodplain to avoid, to the
maximum extent possible, the
adverse impacts associated with
direct and indirect development
of a floodplain.
Requires permit for structures or
work in or affecting navigable
waters.
Potentially Applicable or
Relevant and Appropriate.
Applicable
Applicable
Applicable
No
Comment
The site is not a wild,
scenic, or recreational river
in the National Wild and
Scenic River Systems. It
will be determined if any
part of the site is included
in the inventory of rivers
under consideration.
Wetlands will be
Inventoried and considered.
Floodplains potentially
impacted will be
inventoried and considered.
Surface water of the
Summitville Mine Site are
not navigable within the
meaning of Section 10 of
the Rivers and Harbors Act
of 1899.
-------
Table 7 (continued)
Potential Action Specific ARARs
Potentially Applicable or
Relevant ami Appropriate
Wildlife Commission Regulations
Citation
Slate: 2CCR405-0
Fish and Wildlife Coordination Act 16 U.S.C. §§ 66U666
40 C.F.R. § 6.302(g)
Endangered Species Act
I6U.S.C.§§ 1531-1543
50C.F.R.Parlsl7,402
40 C.F.R. § 6.302(h)
Slate: C.R.S. §§33-2-101,
et seq.
Coastal Zone Management Act
16 U.S.C. §§1451-1464
Description
Establishes specific
requirements for protection of
wildlife.
Requires consultation when
federal department or agency
proposes or authorizes any
modification of any stream or
other water body to provide for
adequate provision for
protection of fish and wildlife
resources.
Requires that federal agencies
insure that any action
authorized, funded, or carried
out by the agency is not likely to
jeopardize the continued
existence of any threatened or
endangered species or destroy or
adversely modify critical
habitat.
Prohibits federal agencies from
undertaking any activity that is
not consistent with a state's
approved coastal zone
management program.
Potentially Applicable or
Pc|cyan( and Appropriate
Applicable
Applicable
Applicable
No
Comment
During the design phase of
the remedy, requirements
for the protection of
wildlife will be met in the
Summitville Mine area.
Prior to modification of
water bodies appropriate
agencies will be consulted.
See section S.I.
A survey of threatened and
endangered species is
underway. Prior to any
action that would jeopardize
the continued existence of
any threatened or
endangered species or
destroy or adversely modify
critical habitat, appropriate
State and Federal agencies
will be consulted. See
section S.3.
The site is not in the
vicinity of a coastal zone.
-------
Table 7 (continued)
Potential Action Specific ARARs
Potentially Applicable or
Relevant and Annronrlate
Citation
National Historic Preservation Act 16 U.S.C. § 470
40 C.F.R. §6.30l(b)
Archeological and Historic
Preservation Act of 1974
Historic Sites Aclof 1935,
Executive Order 11593
36 C.F.R. Part 800
Slate: C.R.S. §§ 24-80-101-108
16 U.S.C. §469
40 C.F.R. §6.30l(c)
16 U.S.C. §§46lelsfio1
40 C.F.R. §6.301 (a)
Description
EPA must account for the
affects of any action on any
properly witli historic,
architectural, archeological or
cultural value Ilial is listed or
eligible for listing on the
National Register of Historic
Places, or the Colorado Register
of Historic Places.
Establishes procedures to
preserve historical and
archeological data which might
be destroyed through alteration
of terrain as a result of a federal
construction project or a
federally licensed activity or
program.
Requires federal agencies to •
consider the existence and
location of landmarks on the
National Registry of Natural
Landmarks to avoid undesirable
impacts on such landmarks.
Potentially Applicable or
Relevant q"d
Applicable
Applicable
Applicable
Comment
A survey will be performed
so that the Colorado Slate
Historic Preservation
Officer may determine if
parts of the site are eligible
for inclusion on the State or
National registers. (See
section 5.2).
A survey will be performed
to identify data that requires
protection during remedial
activities.
A survey will be performed
to identify potential natural
landmarks.
Colorado Wildlife Enforcement and
Penalties
State: C.R.S. §§33-1-101,
et seq.
Prohibits actions detrimental to Applicable
wildlife.
During the design phase of
the remedy, consideration
will be given to the
protection of wildlife.
-------
Table 7 (continued)
Potential Action Specific ARARs
Potentially Applicable or
Relevant and Appropriate Citation
Occupational Safely and Health Act 29 U.S.C. §§651 -678
Federal Mine Safety and Heallli Act 30 U.S.C. §§ 801-962
Hazardous Materials Transportation 49 U.S.C. §§1801-1813,
Act, D.O.T. Hazardous Materials 49 C.F.R. Parts 107,171 • 177
Transportation Regulations
Pescrlpllon
Regulates worker health and
safety.
Regulates transportation of
hazardous materials
Colorado Noise Abatement Statute State: C.R.S. §§ 25-12-101. Establishes standards for
et seq. controlling noise.
Colorado Mined Land Reclamation State: C.R.S. § 34-32-101
Act et seq. and regulations, 2 CCR
407-1
Potentially Applicable or
and Aroriate
No
Regulates working conditions in No
underground mines to assure
safety and health of workers.
Applicable
No
Regulates all aspects of mining, Yes
including location of operations,
reclamation, and other
environmental and
socioeconomic impacts.
Comment
While not an ARAR, these
requirements will apply .
during implementation of
remedies at the site.
While not art ARAR, the
requirements will be met if
it becomes necessary to
access underground mine
workings.
If hazardous materials are
transported offsite these
regulations will be attained.
Will apply to sludges or
spent or process chemicals
if determined hazardous.
While not an ARAR,
applicable standards will be
met during construction
activities at the Summilville
site.
See section 4.6.
-------
Table 7 (continued)
Potential Action Specific ARARs
Potentially Applicable or
Relevant qnd Appropriate
National Prelreatmenl Standards
CitaUflfl
40 C.F.R. Part 403, pursuant to
33U.S.C. § 1317
Description
Potentially Applicable or
Relevant anil Appropriate
Toxic Pollutant Effluent Standards 40 C.F.R. Part 129, pursuant to
33U.S.C. § 1317
Dredge or Fill Requirements
(Section 404)
Marine Protection, Research &
Sanctuary Act
40 C.F.R. Parts 230,231
*
33 C.F.R. Part 323, pursuant to
33 U.S.C. § 1344
13 U.S.C. §§ 1401-1445
Toxic Substances Control Act PCD 15 U.S.C. § 2605(e)
Requirements 40 C.F.R. Part 761
Uranium Mill Tailings Radiation
Control Act
Surface Mining Control and
Reclamation Act
42 U.S.C. §§7901-7942
42 U.S.C. § 2022
30 U.S.C. §§1201-1328
Sets standards to control No
pollutants which pass through or
interfere with treatment
processes in publicly owned
treatment works or which may
contaminate sewage sludge.
Establishes effluent standards or No
prohibitions for certain toxic
pollutants: aldrin/ dieldrin,
DDT, endrin, toxaphene.
benzidine, PCDs.
Requires permits for discharge No
of dredged or fill material into
navigable waters.
Regulates ocean dumping. No
Establishes disposal No
requirements for PCBs
Establishes requirements related No
to uranium mill tailings.
Establishes provisions designed No
to protect the environment from
the effects of surface coal
mining operations.
Comment
No discharge to a publicly
owned treatment works is
anticipated.
The discharge of specified
pollutants is not anticipated.
No construction activities
are applicable involving
dredging in water treatment.
Ocean dumping will not
occur.
At this lime it is not
anticipated that remedial
activities will involve the
disposal of PCBs.
Uranium mill tailings are
not present at the site.
Not relevant. Creates no
substantive cleanup
requirements.
-------
Table 7 (continued)
Potential Action Specific ARARs
Potentially Applicable or
Relevant and Appropriate
SAFE DRINKING WATRR ACT
Underground Injection Control
Regulations
CLEAN WATER ACT
National Pollutant Discharge
Elimination System
Amendment to the Settlement of
July 1,1991
Effluent Limitations
Citation
40 C.F.R.§§ 144.12,144.24,
and 144.25, pursuant to 42
U.S.C.§12l(e)(l)
40C.F.R. Parts 122, 125
pursuant to 33 U.S.C. § 1342
5CCR 1002-2, §§6.1.0 to
6.18.0, pursuant to C.R.S. § 25-
8-501
July 21,1992 agreement
between Co. Mined Reclamation
Board, Co. Mined Reclamation
Division, CO. Water Quality
Control Division, the Executive
Director of the CDPHE and the
SCMCI
40 C.F.R. Part 440, pursuant to
33U.S.C.§I3II
5 CCR 1002-3, §§10.1 to
10.1.7, pursuant to C.R.S. § 25-
8-503
Pescripljon.
Establishes requirements for
injection of waste water into
wells and aquifers.
Requires permits for the
discharge of pollutants from any
point source into waters of the
United States including
stormwater.
Establishes Numerical Criteria
Limits for water quality for
outfall 004 (WF5.5) an a
compliance plan
Sets technology-based effluent
limitations for point source
discharges in the Ore Mining
and Dressing Point Source
category. Also provides
exemption for release of storm
water where denned DMP
criteria are implemented.
Potentially Applicable or
Relevant and Appropriate
No
Applicable
Comment
Underground injection is
not anticipated.
See sections 4.3 and 4.4.
Considered
Relevant and Appropriate See section 4.3.
-------
Table 7 (continued)
Potential Action Specific ARARs
Potentially Applicable or
Relevant an<*
Guidelines for Development and
Implementation of Stale Solid
Waste Management Plans
Criteria Tor Classification of Solid
Waste Disposal Facilities and
Practices
Hazardous Waste Management
System: General
Identification and Listing of
Hazardous Waste
Citation
40 C.F.R. Part 256, pursuant to
42U.S.C. §690l,els£g4
40 C.F.R. Part 257, pursuant to
42U.S.C. §690l,eLS£&
40 C.F.R. Part 260
State: 6 CCR 1007-3 part 260
40 C.F.R. Part 261, pursuant to
42U.S.C. §6921
State: 6 CCR 1007-3 Part 261,
pursuant to C.R.S. § 2S-1S-302
Standards Applicable to Generators 40 C.F.R. Part 262, pursuant to
of Hazardous Waste 42 U.S.C. § 6922
State: 6 CCR 1007-3 Part 262,
pursuant to C.R.S. §25-15-302
Pcscrlpllon
Establishes requirements for
federal approval of.slate
programs to regulate open
dumps.
Establishes criteria for solid
waste disposal facilities and
practices.
Establishes procedures and
criteria for modification or
revocation of any provision in
parts 260-265.
Defines those solid wastes
which are subject to regulation
as hazardous wastes under 40
C.F.R. Pails 262-265 and Parts
124,270.271.
Establishes standards for
generators of hazardous waste.
Potentially Applicable or
Relevant and Appropriate
No
No
No
Applicable
Applicable
Comment
Creates no substantive
cleanup requirements.
Disposal of mine wastes
and closure of mines are
specifically addressed by
the Colorado Mined Land
Regulations, See section
4.2.
Creates no substantive
cleanup requirements.
Provides for (he
identification of hazardous
wastes; used to determine •
disposal criteria for sludges
& spent process chemicals
generated from water
treatment.
If hazardous waste are
generated onsite and
managed offsite thti
requirements are applicable.
Used to handle process
chemicals and sludge
management for water
treatment.
-------
Table 7 (continued)
Potential Action Specific ARARs
Potentially Applicable or
Relevant and Appropriate Citation
SOLID WASTE DISPOSAL ACT f'SWDA"!
Guidelines For the Thermal
Processing of Solid Wastes
40 C.F.R. Part 240, pursuant to
42U.S.G.§690l,elS£Ql
Guidelines for the Land Disposal of 40 C.R.S. Part 241, pursuant to
Solid Wastes 42 U.S.C. § 6901,
Colorado Regulations Pertaining to
Solid Waste Disposal Sites and
Facilities
Guidelines for the Storage and
Collection of Residential,
Commercial, and Institutional Solid
Waste
Source Separation for Materials
Recovery Guidelines
Slate: 6 CCR 1007-2, pursuant
toC.R.S. §30-20-101 and
C.R.S. §30-20-102,
40 C.F.R. Part 243, pursuant to
42H.SC. 669Ql.etseq.
40 C.F.R. Part 246, pursuant to
42U.S.C.§6901,£Ls£Qt
Description
Prescribes guidelines for
thermal processing of municipal
solid wastes.
Establishes requirements and
procedures for land disposal of
solid wastes.
Establishes requirements and
procedures for land disposal of
solid wastes and the siting of
disposal facilities.
Establishes guidelines for
collection of residential,
commercial, and institutional
solid wastes.
Establishes requirements and
recommended procedures for
source separation by federal
agencies of residential,
commercial, and institutional
solid wastes.
• Potentially Applicable or
Relevant and Annronrlate
No
No
No
No
No
Comment
Thermal processing will not
occur.
Disposal of mine wastes
and closure of mines are
specifically addressed by
the Colorado Mined Land
Regulations. See section
4.2.
Disposal of mine wastes
and closure of mines are
specifically addressed by
the Colorado Mined Land
Regulations. See section
4.2
Not relevant.
Not relevant. Creates no
substantive cleanup
requirements.
-------
Table 7 (continued)
Chemical Specific Criteria To-Dc-Considcrcd (TBC)
Standards, Requirements,
Criteria. limitation;
RCRA Groundwater Protection
Standard (RCRA GPS)
SURFACE WATER:
Colorado Water Quality
Standards
Citation
40 CFR§§ 264.92-264.101
Stale: 6 CCR 1007-3
State: 5 CCR 1002-8. §§ 3.1.0-
3.1.17
Dcscrlntlon
Potentially Applicable or
Relevant and Appropriate
Establishes standards for ground No
water quality related to RCRA
hazardous waste facilities.
Establishes standards and
classifications for Colorado
surface waters.
Federal Water Quality Criteria 40 C.F.R. Part 131
Sets criteria for surface water
quality based on toxicily to
Quality Criteria for Water, 1986, aquatic organisms and human
pursuant to 33 U.S.C. § 1314 health.
Applicable
Coirjment
The Slate of Colorado has
comprehensive ground-
water classification system,
including numeric standards
equivalent to MCLs and
RCRA GPS.
See section 3.1.1.
Relevant and Appropriate See section 3.1.2.
AIR:
National Primary and Secondary 40 C.F.R. Part 50, pursuant to 42
Ambient Air Quality Standards U.S.C. § 7409.
State: C.R.S. § 25-7-108, 5 CCR
1001-14.
Establishes standards for
ambient air quality to protect
public health and welfare
(including standards for
pariicnlale mailer and lead).
Applicable
National Emission Standards for 40 C.F.R. Part 61, Subparts N, O, Sets emission standards for No
Hazardous Air Pollutants P pursuant to 42 U.S.C. § 7412. designated hazardous pollutants.
Slate: C.R.S. § 25-7-108,5 CCR
1001-10
See section 3.4.
Air emissions are not
anticipated after
construction activities are
complete. See section 3.4.
-------
Table 7 (continued)
Chemical Specific Criteria To-Bc-Considercd (TBC)
Advisories lo be
Considered nn(l Guidance Citation Description To Be Considered Comrnent
SOILS:
Toxic Substances Control Acl, PCD 52 FR 10688 April 2,1987 Establishes guidance cleanup Not considered There is no evidence that
Spill Cleanup Policy levels for PCB contaminant PCB spills have occurred.
soils.
Interim Guidance on Establishing EPA Directive 09335.4-02, Established guidance cleanup Considered See section 3.3.
Soil Lead Cleanup Levels at September 1989. levels Tor lead contaminated
Superfund Sites soils.
-------
Tublc 7 (continued)
Potential Action Specific ARAKs
Polenliully Applicable or
Relevant and Appropriate
Standards Applicable lo
Transporters of Hazardous Waste
Standards for Owners and
Operators of hazardous Waste
Treatment, Storage, and Disposal
Facilities
Interim Standards for Owners an
Operators of Hazardous Waste
Treatment, Storage, and Disposal
Facilities
Standards for the management of
Specific hazardous Wastes and
Specific Types of Hazardous Waste
Management Facilities
Citation
40 C.F.R. Part 263, pursuant to
42 U.S.C. § 6923
State: 6 CCR 1007-3 Part 263,
pursuant to C.R.S. § 25-15-302,
4 CCR 723-18
40 C.F.R. Part 264, pursuant to
42 U.S.C. § 6924,6925
State: 6 CCR 1007-3 Part 264,
subparts B, C, D, B, F, 0, K, L,
and N, pursuant lo C.R.S. §
25-15-302
40 C.F.R. Part 265
State: 6 CCR 1007-3, Part 265
40 C.F.R. Part 266
State: 6 CCR 1007-3, Part 267
Interim Standards for Owners and 40 C.F.R. Part 267
Operators of New Hazardous Waste
Land Disposal Facilities State: 6 CCR 1007-3, Part 267
pescrlplloii
Establishes standards which
apply lo persons transporting
hazardous waste within the U.S.
if the transportation requires a
manifest under 40 C.F.R. Part
262.
Establishes standards which
define the acceptable
management of hazardous waste
for owners and operators of
facilities which treat, store, or
dispose of hazardous waste.
Establishes standards for
management of hazardous waste
during interim status.
Potentially Applicable or
Relevant and Appropriate
Applicable
Yes
Relevant and Appropriate
Establishes requirements which No
apply to recyclable materials
that are reclaimed to recover
economically significant
amounts of precious metals,
including gold and silver.
Establishes minimum national No
standards Iliat define acceptable
management of hazardous waste
for new land disposal facilities.
Comment
If hazardous wastes are
transported offsite the
requirements are applicable
See section 4.1.
Establishes no substantive
standards applicable or
relevant and appropriate to
the HLP.
Not relevant to activities at
the site.
Part 267 regulations are no
longer effective after
February 13, 1983.
-------
Table 7 (continued)
Potential Action Specific ARARs
Potentially Applicable or
Relevant qn.d Appropriate
Hazardous Waste Permit Program
Underground Storage Tanks
Citation
40 C.F.R. Part 270
State: 6 CCR 1007-3, Part 100
40C.F.R.Part280
Description
Establishes provisions covering
basic EPA permitting
requirements.
Potentially Applicable or
Relevant and Appropriate
No
Establishes regulations related to No
underground storage tanks.
Cqmment
A permit is not required for
onsite CERCLA response
actions.
The use of or remediation
. of underground storage
tanks is not anticipated.
-------
TableS
Numeric Surface Water Quality Goals and ARARs
Alamosa River - Monitoring Station AR-45.4
METAL
PH
A-**-
Arsenic, acute
CaJinnm. chrome
Chrome VL cnio&tc
Copper, chrome
Cysnrae
Innu chmiHr
LaAdmaric
Mftng&sese. chronic
Mercury, chrome
NicioeL chronic
Zioc.cb.me
SURFACE WATER QUALTTY COALS
ciass irrvs)
6J-9.0
STugfldinoivatMcy t ttooughSejjnanberMooiy. FortaJmccof
yttt doanie • Acute TVS - TSOugrt diootvai
jOug/U totti tecovcnbte. I-dsy
2Jagrt dissolved @ 250mgfl hmtoea
1 lug/I disjolvcd
30ugrl dissolved, bucd upon ft<«** p»»»^<
-------
TABLE 9
5-1
5-2.
5-3-
5-4-
5-5-
5-6-
Altemative
No Action
HEAP LEACH PAD REMEDIAL ALTERNATIVES
Remedial Activities
Pump & Treat/Recontour& Cap
Injection-Extraction Wells/
Pump & Treat/Biotreatment/
Recontour & Cap/Bioreactor
Extraction Pumps & Underdrippers/
Water Rinse/Recontour & Cap
Partial HLP Removal/Injection-
Extraction Wells/Water Rinse/
Recontour & Cap
Pump & Treat/Total HLP Removal/
Ex situ Ore Treatment
Disposal On-Site
Monitoring
Pump & Treat Leachate; Grade,
Recontour, Cap & Revegetate; Seepage
Collection with Standby Water
Treatment; Monitoring
Injection-Extraction Well Solution
Collection; Pump & Treat Leachate;
Biotreatment; Grade, Recontour, Cap &
Revegetate; Surge Pond; Bioreactor;
Monitoring
Water Rinse HLP; Grade,
Recontour, Cap & Revegetate; Continual
Standby Water Treatment; Monitoring
Remove Top Section of HLP to
Mine Pit; Injection-Extraction Well
Solution Collection; Water Rinse;
Grade, Recontour, Cap & Revegetate;
Monitoring
Pump & treat Leachate; Total HLP
Removal; Dispose & Soil Wash HLP
Solids On-Site; Amend Footprint & Cap
Areas; Monitoring
-------
Table 10
Comparative Analysis of Alternatives
Alternative
Efleellventss '
Allema(lve5-l:
None
No Action
Alternative 5-2:
Yei
Pump and Treat/
Reconlour and Cap
Alternative 5-3
Yei
Injection-Extraction
Wells/Pump and
Treal/Blotreatmenl/Recontour
and Cap/Bioreaclor
Alternative 5-4:
Yes
Extraction Pumps/Water
Rlnse/Recontour and Cap
Alternative 5-5:
Yes
Partial IILP Removat/lnjecllon-
Exlraclion Wells/Water
Rlnse/Recontour and Cap
Alternative 1-6:
Yes
Pump and Treat/Total IILP
Removal/Ex Situ Ore
Treatment/Disposal On Site
Protection of
Health and
Environment
Implcmenlablllly
None
Moderate
High
Moderate
High
High
Ixmg-Term
EtTeellveneis
Costs
None
Moderate
High
Moderate
High
High
Compliance with
ARAIli
None
Yes
Yes
Yes
Yes
Yes
deduction In •
Toilclly, Mobility
or Volume
None
Yes
Yes
Yes
Yes
Yes
Short-Term
None
Yes
Yes
Yes
Yes
Yes
ImpUmenlalilllfy
Easy
Moderate
Moderate
Easy
Moderate
Difficult
Costs
$261,000
$13,772,000
$18,929.000
$21.411.000
$22,923,000
$74,176,000
-------
ENVIRONMENTAL CHEMICA1
CORPORATION
ENLARGED AREA MAP .
•Modified tram MK. Summitvilte H.ap u«ch P*d lnv..tlg.tlon R.porl SumraJtvill.. Colorado
-------
rma riid 14 «
-------
yo»o>/i»/ntiiini HI it AMI >
-------
MINE rooi?ni»r
<* v£2>y sunrACC stcnA<* **«a
MINE FOOT PRIHTo -,,«4 smwu-wowceiiciicriiffl,
tA -/^
H\' *#ViV
)f^-A
•• I »
-------
ft. / --•'•'•••fia...'*.-
J.-T—/ -.•**-<*j:-j
«o> -X •-. ' -f • '
r"f .. . V .. ' "; _\l-i. •. • ••• .
V I -.-• • «Se»l«M*
------- |