Summary of Remedial Alternative Selection Iron Mountain Mine Redding California


RECORD OF DECISION
IRON MOUNTAIN MINE
REDDING, CALIFORNIA

DOCUMENTS REVIEWEDt

I am basing my decision primarily on the following documents
describing the cost-effectiveness of remedial alternatives for
the Iron Mountain Mine sites

*	Final Remedial Investigation Report, Iron Mountain Mine,
near Redding, California, CH2M Hill, August 1985.

*	Public Comment Feasibility Study, Iron Mountain Mine, Redding,
California, CH2M Hill, August 2, 1985.

*	Public Comment Feasibility Study Addendum, Iron Mountain
Mine, Redding, California, dated July 25, 1986.

*	Responsiveness Summary, dated September 1986.

*	Summary of Remedial Alternative Selection, September 19, 1986.

DESCRIPTION OF OPERABLE UNIT:

*	Cap selected cracked and caved ground areas on Iron Mountain
above the Richmond ore body using a soil-cement mixture or
other suitable material *;

*	Divert clean surface water in Upper Spring Creek to Flat
Creek, divert clean surface water in South Fork Spring
Creek to Rock Creek, and divert clean Upper Slickrock Creek
water around waste rock and tailings piles;

*	Enlarge Spring Creek Debris Dam (SCDD) from its present
capacity of 5,800 acre feet to 9,000 acre feet;

*	Implement perimeter control as needed to minimize direct
contact threat; and

*	Perform hydrogeologic study and field-scale pilot demonstration
to better define the feasibility of utilizing low-density
cellular concrete to eliminate or reduce acid mine drainage
formation.

* [Based on the present record, I believe that construction
of a partial cap over the Richmond ore body is a necessary source
control component of the overall remedy as envisioned by EPA.
However, the potentially responsible parties are proposing to

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u

* implement a solution mining operation that may be able to

effectively exploit the ore body as a resource and control the
• *" discharge of acid mine drainage from the mountain. Construction
of the partial cap could adversely affect the solution mining
operation. EPA intends to further explore the implementation
and environmental-results associated with a solution mining
operation during the next 60 days. Therefore, no action will be
taken to implement the capping component for a period of at
least 60 days from the signature date on this Record of Decision.
To the extent that new information causes EPA to modify its
present opinion that the mountain should be partially capped,
EPA would provide to the public an opportunity to comment prior
to making any final decision. I will make a decision regarding
the implementation of the capping component after the 60-day
period has ended.]

DECLARATIONS*

Consistent with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA) and the National
Oil and Hazardous Substances Pollution Contingency Plan (NCP)
40 CFR Part 300 et.seq., I have determined that the operable
unit remedy previously identified is a component of what will be
the appropriate Fund-financed action for this site in accordance
with section 300.68 (j) of the NCP. These are components of a
final EPA remedy that will provide adequate protection of the
public health and welfare and the environment.

The selected operable unit, and ultimately the final remedy,
/ will not meet all the requirements of the Clean Water Act (CWA)
33 U.S.C. $1251 et.seq. and, therefore, is somewhat less protec-
tive than the remedial action alternative that complies with all
federal and state regulations. The reason is that federal water
quality standards will be met in the Sacramento River below
Keswick Dam but not in the immediate receiving waters as required
by the CWA. Also, if treatment is required, not all point source
discharges will receive Best Available Technology and not all
non-point sources will be addressed through Best Management
Practices. However, the final remedy is expected to be substan-
tially effective in minimizing the discharge of heavy metals from
the site which would threaten public health and welfare or the
environment. I have determined that the level of protection
provided by the operable unit most effectively mitigates and
minimizes threats to and provides adequate protection of public
health and welfare and the environment considering the need for
additional protection at this site and the amount of money that
may be available in the Hazardous Substance Trust Fund to respond
to other sites which present or may present a threat to public
health and welfare and the environment. I have also determined

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that the selected remedy is that remedy which most closely
approaches the level of protection provided by applicable or
relevant and appropriate Federal requirements considering the
specific fund-balanced sum of money available for the Iron
Mountain Mine site.

The State of California has been consulted and agrees with
the approved operable unit and EPA's strategy leading to the
implementation of a final remedy. All aspects of the Iron Mountain
Mine remedy will be implemented in a phased approach* with the
enlargement of Spring Creek Debris Dam (SCDD) being the last
component remedy constructed. The reason for this is that the
actual effectiveness of the other component source control,
treatment, and water management alternatives will not be known
until each component has been installed and monitored. Only
until these actions are completed will EPA know the exact enlarge-
ment of SCDD needed to ensure that project cleanup objectives
will be met. Therefore, this ROD will authorize enlargement of
SCDD, but EPA will not begin the remedial action phase until the
effectiveness of other component remedies has been determined.
The operable unit will require future operation and maintenance
activities to ensure the continued effectiveness of the alterna-
tives. These activities will be considered part of the approved
action and eligible for Trust Fund monies for a period not to
exceed one year.

I have determined that a hydrogeologic investigation and a
field-scale pilot demonstration test to determine the technical
feasibility of injecting low-density cellular concrete into the
underground mine workings, are appropriate next steps in determin-
ing the scope of the final remedy for Iron Mountain Mine. EPA
believes that low-density cellular concrete may constitute a
permanent approach to the reduction of acid mine drainage
formation.

Date

Assistant Administrator,
Office of Solid Waste and
Emergency Response

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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION

Iron Mountain Mine
Redding/ California

September 19, 1986
Prepared by Thomas A. Mix
Federal Response Section
Toxics and Waste Management Division
United States Environmental Protection Agency
215 Fremont Street
San Francisco, California 94105

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It,

TABLE OF CONTENTS

I. Site Location and Description			 1

II. Overview of the Problem					 3

III. Site History	 4

A.	Mining History 	 4

B.	Previous Remedial Actions 		 6

IV. EPA Involvement 		 8

A. Remedial Investigation 	 8

V. Enforcement Analysis 	 27

VI. Alternatives Evaluation 			 27

A.	Introduction 		27

B.	Site-Specific Action Levels				29

C.	Technology Development 		29

D.	Components for Detailed Analysis 	».		30

E.	Description of Combined Remedial Action

Alternatives 	 41

F.	Alternative Screening 	 44

VII. The Iron Mountain Mine Remedy 	 49

VIII. Fund- Balancing 	 50

IX. Summary Evaluation of Alternatives 	 52

A.	Features and costs of combined remedial
activites	53

B.	Evaluation of combined remedial alternatives 54

X. Identification of Fund- Balanced Remedy and

Remedy Selection Strategy 	 56

XI. Summary of Recommended Operable Unit 	 58

XII. Recommended Cleanup Objectives and

Design Year 					 59

XIII.	Consistency with Other Environmental Laws 		59

XIV.	Operation and Maintenance 		63

XV.	Community Relations 				63

XVI.	Schedule 		66

XVII.	Future Action 		67 .

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LIST OF FIGURES

Figure 1. Iron Mountain Mine Location Map	 2

Figure 2. Slickrock Creek Intensive Sampling

Site Location Map	 9

LIST OF TABLES

Table 1. Relative Contribution of Metals from Sources	11

Table 2. Average Chemical Composition o£ Discharges

from 5 Major Sources 	.	 12

Table 3. Boulder Creek Hater Quality	.	 14

Table 4. Percent Contribution of Boulder Creek Seeps and

Tailings Piles/Waste Rock Dumps 	 16

Table 5.	Slickrock Creek Water Quality 	 17

Table 6.	Spring Creek Water Quality 		 20

Table 7.	Summary of Sacramento River Monitoring 	 21

Table 8.	Summary of Fishkills Near Redding, California ... 23

Table 9.	Available Technologies				 31

Table 10.	Components Retained for Detailed Analysis 	 32

Table 11. Technical Environmental and Institutional

Considerations for Remedial Action Components ..33

Table 12. Combined Alternatives Matrix 		 46

Table 13. Anticipated Water Quality Improveim ts with

CA-9 	 57

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SUMMARY OF
„ REMEDIAL ALTERNATIVE SELECTION

SITE: Iron Mountain Mine
REGION: IX

I. SITE LOCATION AND DESCRIPTION

Iron Mountain Mine is located in the southeastern foothills
of the Klamath Mountains, approximately nine miles northwest of
the City of Redding, California (See Figure 1). Between the
1860's and 1962, Iron Mountain Mine was periodically mined for
iron, silver, gold, copper, zinc, and pyrite. The mine area is
located on 4,400 acres of property that includes underground
workings, an open pit mining area, waste rock dumps, and tailings
piles. The rugged topography of the area is typical of a
mountainous region with steep slopes bissected by streams.
Elevations range from 600 feet on the Sacramento River several
miles east of the mine, to 3,800 feet on top of Iron Mountain.
The climate of the Iron Mountain area is characterized by warm,
dry summers and cool, rainy winters.

Iron Mountain averages 70- 80 inches of precipitation per
year, most of it falling in the form of rain between the months
of November and April. Snow accumulation of several inches is
common above the 2,000 foot elevation during the November- March
storms, but usually melts in a few days.

Iron Mountain is drained by Boulder Creek to the north, and
Slickrock Creek to the south of the mine. Boulder Creek, a
perennial stream, receives a portion of its flows from the Lawson
and Richmond adits via their mine portals. Slickrock Creek, an
intermittent stream, receives discharges from underground
seepage associated with Old Mine and/or No. 8 Mine and flows
from storm water drainage from the Brick Flat Pit area. A debris
slide diverted the original Slickrock Creek drainage and buried
adits from which acid mine drainage is emanating. Two copper
cementation-plants are located on site and function to remove
copper from controlled flows, such as those collected from mine
portals and conveyed to the plants by a system of flumes.
Uncontrolled flows such as surface runoff containing acid and
heavy metals are discharged directly to receiving waters without
treatment.

Slickrock and Boulder Creeks flow southeastward into Spring
Creek. The Spring Creek Debris Dam and Reservoir were built in
1963 as part of the Central Valley Project (CVP). Since 1963,
the waste has been collected in Spring Creek Reservoir jand sub-
sequently metered into Keswick Reservoir. The flow releases of
the waste from the Spring Creek Reservoir is determined by the

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amount of "dilution" water being released by the U.S. Bureau of
Reclamation from Shasta Lake. A principle objective in operating
the reservoir is to control the discharge of the contaminated
water such that releases upstream from Shasta Lake provide
sufficient dilution to meet current established levels for copper,
zinc, and cadmium in the Sacramento River. Spring Creek drains
into Keswick Reservoir which was formed by the construction of
the Keswick Dam on the Sacramento River. Plat Creek, which also
drains a portion of the mining complex, enters Keswick Reservoir
just upstream of Spring Creek. The Sacramento River is a valuable
fisheries resource and is used as a source of drinking water by
the City of Redding (population: approximately 50,000 people).

II. OVERVIEW OF THE PROBLEM

Mineralized zones that have extensive underground workings
from past mining activities are the primary source of contamina-
tion. As rain falls on the ground above the mineralized zones,
it infiltrates into the underground mine workings where it mixes
with groundwater, and then passes through the ore zone. As the
groundwater passes through the ore, sulfuric acid is produced,
and high concentrations of copper, zinc, and cadmium are leached
from the mineralized zone. The resulting heavy metals- laden
acidic waters are referred to as acid mine drainage (AMD).

The AMD is eventually discharged through mine adits (access
tunnels entering the orebody and used during underground mining
activities) or groundwater seepage into streams in the Spring
Creek watershed (Slickrock Creek and Boulder Creek). The AMD
mixes with runoff from the Spring Creek watershed and flows into
Spring Creek Reservoir. This reservoir serves to control discharges
from the Spring Creek watershed into the Sacramento River.

During periods of heavy winter rain, high volumes of runoff
are produced from the Spring Creek watershed. This also coincides
with high production of AMD from Iron Mountain Mine. At these
times, releases from Shasta Lake are frequently reduced to maximize
storage behind Shasta Dam and to prevent downstream flooding of
the Sacramento River. When high runoff causes the Spring Creek
Reservoir to exceed capacity, uncontrolled spills have occurred.
Under these conditions, the releases from Shasta Lake are at times
not sufficient to provide adequate dilution of the uncontrolled
discharge from the reservoir. As a result, levels of copper,
zinc, and cadmium exceeding lethal concentrations for aquatic
life periodically occur in the Sacramento River. The last major
adult fish kill occurred in 1969 when an estimated 200,000 salmon
were killed. More often, sublethal concentrations occur that
have detrimental effects on some aquatic species, including
reduced rates of growth, interference with physiological processes
necessary for successful migration, and inhibition of gill function.
Past investigations in the Iron Mountain Mine area have documented
the following environmental conditions which now exist and will
continue as a result of toxic drainage from Iron Mountain Mine.:

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1.	Heavy Hiatal contamination of Bould«r Creek, Slickrock
Creek, Flat Creek, and portions of Spring Creek, causing
the elimination of aquatic life and all other beneficial
uses of these watercourses downstream of Iron Mountain
Mine.

2.	Heavy metal contamination of Keswick Reservoir, causing
periodic fish kills ad a significant reduction in fish
and aquatic invertebrates and unsightly deposits of
metallic sludges in the lower one and one-half miles

of the Reservoir downstream of Sprinq Creek. This con-
tamination has reduced, if not eliminated, recreational
uses of the lower Reservoir.

3.	Periodic fish kills in Keswick Reservoir and in the
Sacramento River downstream of Keswick Dam caused by
uncontrolled spills of contaminated water from Spring
Creek Reservoir. In addition, there are repeated
instances when the LC50 levels for juvenile salmon and
steelhead in the Sacramento River below Keswick Dam are
exceeded. These instances are caused by uncontrolled
spills at Spring Creek Reservoir. In addition, short-
term exposure (6-8 hours) to high concentrations of
heavy metals occurs below Keswick Dam from normal water
releases at Spring Creek Reservoir during the Spring
Creek powerhouse start-up.

4.	Accumulation of copper and cadmium in the tissue of
resident fish below Keswick Dam at levels which greatly
exceed the statewide norm and which suggest adverse
reproductive and other physiological impacts. In

the case of cadmium, the levels in fish tissue below
Keswick Dam are over five times the statewide norm.

5.	Temporary discontinuation of domestic water from the
Sacramento River for precautionary reasons during
uncontrolled spill events at Spring Creek Reservoir.

6.	Occasional loss of larje volumes of fresh water in
storage when the U.S. Bureau of Reclamation has had

to release water from Shasta Dam to dilute high concen-
trations of heavy metals spilling from Spring Creek
Reservoir.

III. SITE HISTORY

A. Mining History

Iron Mountain Mine is the southernmost mine in the West
Shasta Mining District, an area mined since the early 1860's for
silver, gold, copper, zinc, and pyrite. Although various parts

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- 5 -

of Iron Mountain*Mine were developed as separate mines* it is
generally believed that the massive sulfide deposits are part of
one orebody which has been segmented by faulting.

Iron Mountain Mine was first secured for possible future
value as a source of iron ore in 1865. Silver ore was discovered
in 1879, and limited development and mining or Iron Mountain
Mine's gossan (oxide ores) caps began. A small milling and
leaching facility was constructed in the mid-1980's to process
the gossan material for silver recovery. -In 1895# the Iron
Mountain Mine property was sold to British-owned Mountain Mining
Company, Ltd., following discovery of massive copper sulfide
deposits. Mining of the ore continued under the new ownership
until 1897, when the property was transferred to Mountain Copper
Company, Ltd., of London, England.

The Old Mine orebody was the first massive sulfide ore to
be mined for commercial recovery of copper at IMM. Construction
of a smelter and a narrow-gauge railway to transport the ore
from the mine to the smelter was completed in 1896.

Between 1902 and 1908, several lawsuits were brought against
Mountain Copper Company. Private property owners and the U.S.
Forest Reserve sued Mountain Copper for destruction of vegetation
by operation of the Keswick smelter, and an injunction was obtained
prohibiting the roasting of ore. Smelting was gradually transfer-
red to Richmond, California, and in 1907 the Keswick smelter was
completely shut down. Mountain Copper completed a new smelter
and processing plant in Martinez, California in 1908.

The Number 8 orebody, underlying the Old Mine orebody, was
discovered in 1907. The Number 3 Mine was developed concurrently
with the Hornet pyrite mine on the northeast side of the mountain.
Beginning in 1900, pyrite ore from the Old Mine, and later the
Hornet Mine, was sold for the production of sulfuric acid.

Process residues were returned to Mountain Copper Company's
Keswick Smelter for recovery of the copper, gold, and silver.
The procedure was greatly simplified with completion of Mountain
Copper's Martinez plant in 1908. The Martinez plant was complete
with copper smelter, an acid plant, and facilities for manufactur-
ing commercial fertilizers.

In 1914-15, California's first copper flotation mill
was completed at Minnesota, on the Iron Mountain railway. The
mill operated until March 1919, when it was closed because of
low copper prices. A nearly flat area, later referred to as
Minnesota Flats, was used for tailings disposal during the
operation of the mill. Pyrite ore tailings were also deposited
at Minnesota Flats during later periods of mining.

In 1920, a new crushing and screening plant was put into
operation near the Hornet Mine to replace the crushing opera-
tions at Keswick. It was operated until 1943. An aerial tramyay

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was completed in 1921 to transport the ore to Matheson, a few
miles north of JEeswick on the Southern Pacific Railroad line.

In 1928, as the copper market improved, the Minnesota mill
was reconstructed just below the Number 8 Mine portal. However,
tailings disposal in the steep canyon was a major problem; a
tailings dam built on Slickrock Creek received numerous complaints
from the California Pish and Game Commission. The dam was
destroyed by floods in 1933, and the operation was shut down due
to declining copper prices. A 250-ton/day cyanide leach plant
was constructed in 1929 to recover silver and gold from the
gossan in the area of the Old Mine orebody. The gossan was
23ned by open-pit methods, with tailings storage in Hogtown
Gulch, adjacent to Slickrock Creek. An estimated 2.6 million
tons of gossan was mined from 1929 to 1942. The tailings initially
stored in Hogtown Gulch, were reported to have an iron content
of 50 to 55 percent; during later periods, the content was reported
to be as low as 30 to 35 percent.

Mining of the copper-zinc ore in the Richmond and Mattie
orebodies was begun in 1942. High wartime metals prices prompted
construction of a copper-zinc flotation plant at the Richmond
portal. The plant operated from 1943 to 1947. Underground
mining of the Richmond orebody ended in 1956.

In 1955, a large landslide composed of mine mill tailings
filled the Slickrock Creek canyon to a reported depth of about
80 feet, covering two mine portals (Number 8 and Old Mine).

~

The Brick Plat orebody was mined by open-pit methods between
1955 and 1962. The first pyrite was mined in 1956 after the
removal of 2.5 million tons of overburden. All mining operations
were discontinued in 1963.

The Iron Mountain property was purchased from Mountain
Copper Company by Stauffer Chemical Company in 1967. The property
was subsequently sold to Iron Mountain Mines, Inc., in 1976.

There has been some core sampling, but there is no evidence that
mining has occurred under the current ownership.

B. Previous Remedial Actions

Several actions have been taken that have had an effect on
the incidence and severity of AMD problems at Iron Mountain Mine.
These measures, although lessening the pollution problems somewhat,
have not been successful in eliminating the conditions discussed
on page 4 of this document.

1. Copper Cementation Plants

In 1940, Mountain Copper Company, Ltd., constructed a copper
cementation plant to recover copper from mine drainage in the
Boulder Creek drainage area. In the cementation process, scrap

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iron is contacted with the AMD resulting in the precipitation of
copper and dissolution of the scrap iron.

The Boulder plant and a similar plant in the Slickrock
drainage, which was constructed by Iron Mountain Nines, Inc., in
1977, have been operated intermittently to recover copper from
the AMD, thereby reducing concentrations of copper in Spring
Creek and the Sacramento River. The copper cementation plants
remove approximately 300 pounds per day (annual average) of
copper from the AMD when properly operated* Zinc and cadmium,
and other elements are not removed by this treatment method.

2. Spring Creek Debris Dam

The SCDD was constructed in part to help prevent toxic
concentrations of metals and consequent fishkills as a result of
discharges of AMD to Keswick Reservoir. The objective is to
release AMD from SCDD at a rate which will result in safe metal
concentrations below Keswick Dam. The debris dam has not been
entirely effective in achieving this objective, particularly
during periods of high precipitation which can produce runoff
that exceeds storage capacity of SCDD. This results in un-
controlled spills of AMD. When Sacramento River base-flow is
being stored at the same time to conserve water in Shasta Lake
or to minimize downstream flooding, these acid metal-laden flows
from SCDD are not diluted sufficiently to prevent fishkills,
especially in the early life stages of fish.

In 1980, a Memorandum of Understanding (MOU) was developed
between the State Water Resources Control Board (SWRCB), U.S.
Bureau of Reclamation (USBR), and the California Department of
Fish and Game (CDFG) for the purpose of minimizing the Spring
Creek toxicity problem.

As part of this MOU, the USBR agreed to operate the Spring
Creek Debris Dam and Shasta Dam water management system in
such a manner that, to the extent possible, sufficient dilution
water would be available to ensure that State water quality
criteria below Keswick Dam would be met.

Also, under the agreement, the CDFG was to conduct fish
toxicity tests to provide a basis for permanent toxicity criteria,
release schedules, and water quality objective. After two
years of intensive laboratory and field work, the CDFG identified
the following levels of metals below which protect all life
stages of anadromous salmon and steelhead below Keswick Dam:
'copper (5.6 ug/1); zinc (16.0 ug/1); and cadmium (0.22 ug/1).

These recommended levels were adopted by the Regional Water
Quality Control Board as Basin Plan objectives for the Keswick
Dam area and approved by the State Water Resources Control Board
(SWRCB) in August 1984. These objectives were approved by EPA
on August 7, 1985 under Section 303 of the Clean Water Act.

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M,

The Regional],. Boards acting on behalf of the SWRCB, was
responsible for undertaking environmental studies designed to
identify the most feasible means of mitigating the problem through
source control. The MOU may be revised once remedial action is
completed at Iron Mountain Mine.

IV. EPA INVOLVEMENT

In June 1981, the State of California submitted the Iron
Mountain Mine site as a candidate for the Interim Priorities
List (IPL). When the IPL was released in October 1981, Iron
Mountain Mine appeared in the fourth decade of candidate sites.
Later, on August 31, 1982, the state submitted Iron Mountain
Mine as a candidate for the National Priorities List (NPL). On
December 30, 1982, EPA proposed the Iron Mountain Mine site for
inclusion on the NPL. On September 8, 1983, through final rule-
making, the site was included on the NPL.

In September 1983, EPA commenced a Remedial Investigation
and Feasibility Study (RI/FS). The purpose of the RI was to
assess the major sources of contamination leaving the site and
collect data needed to identify and evaluate potential remedies.
During the FS, the potential remedies were evaluated according
to technical, environmental, public health, institutional, and
cost criteria.

A. Remedial Investigation (RI)

A comprehensive investigation for the Iron Mountain Mine
site was conducted between September 1983 and April 1985 to
determine the nature, cause and extent of the environmental
and potential public health impacts from past and continuing
discharges of AMD. The extent of the surface and ground water
contamination was established through:

*	Weekly sampling of the five major sources at the mine and
three locations on Spring Creek, and bi-weekly sampling at
4 locations along the Sacramento River for heavy metals.

° Installation of flow measurement stations at 8 locations,
including mine portals and downstream receiving waters.

*	Measurement of precipitation at six gauges throughout the
area.

*	Two comprehensive surface water sampling surveys, involv-
ing 76 sampling points were conducted in September 1983
and December 1983 to identify and quantify all AMD sources.
(See Figure 2)	.

*	A review of existing information on the site including
water quality, geology, and hydrology.

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* A program of field mapping of the areas overlying the
Richmond orebody. This included geologic mapping, measure-
ment of fracture orientations, and delineation of subsidence
pits and their tributary drainage areas.

• A program of drilling and monitoring for the Richmond
groundwater investigation. This program included install-
ing four monitoring wells adjacent to the Richmond orebody,
monitoring groundwater elevations, conducting aquifer
testing, and groundwater quality testing.

During the 17 month RZ, approximately 450 surface and ground
water samples were collected and analyzed. A draft RI report
was released in December 1984; the RI report was finalized
and issued on August 23, 1985. The major findings of the RI
are discussed below.

1. Major Sources of Pollution

EPA's RI found that the following five major sources
account for approximately 72 percent of the copper and 86
percent of both zinc and cadmium being discharged from the
site during the sampling period.

Richmond Portal: This source is a mine adit into the
Richmond orebody which represents the major single source
of AMD at Iron Mountain Mine. The Richmond orebody has
been extensively mined, resulting in subsidence pits and
closed drainages on the surface overlying the zone. Water
which drains from the Richmond portal results from infiltra-
tion of surface water captured in the closed drainage areas
overlying the orebody and by lateral inflow of groundwater
from areas upgradient of the mine.

Lawson Portal: This source is a mine shaft located on
Boulder Creek immediately below and to the east of the
Richmond portal.

Old No. 8 Mine Seep: This source is located on the upper
end of Slickrock Creek and is believed to originate from
either the No.8 Mine and/or the Old Mine. The entryways
for these mines were covered by a slide in the 1950's.

Big Seep (below Okosh Mine): This source is made up of
seeps which discharge from the waste rock dump on the
south side of Slickrock Creek.

Brick Flat Pit By-Pass: Water that is discharged from this
source originates from the drainage area into Brick Flat Pit
and is carried outside the pit by an earthen dam.

The relative contribution of metals from these sources is
listed in Table 1; the average chemical composition of discharges
from these sources is shown on Table 2.

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-11.

Table 1. Relative Contribution of Metals
Averaged over 4 month Sampling Program

MAXIMUM

COPP

ENC

CADM1

CUM

DISCHARGES

SOURCE

Average

Ibs/dav

1 of All
Sources

Average

lbs/day

« Of All
Sources

Average

lbs/day

t of All
Sources

Cu,Zn t Cd
Lbs/Day

Richmond
Portal

180

31.0

1# 118

70.0

7.8

69.0

5,600

Lavson
Portal

6.0

209

11.0

1.4

11.0

1,100

Old No. 1
Mine Seep

109

25.0

3.0

0.4

4.0

1,000

Big Seep

9.0

1.0

0.2

1.0

400

Brick Flat
Pit By-
Pass

2.0

1.0

0.6

1.0

1,000

Other
Sources

27.0

14.0

TOTAL 4 23

100.0 1,466 100.0 10.4 100.0

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Table 2
SUMMARY Of MAJOR SOURCES

AVERAGE CHEMICAL COMPOSITION

(DECEMBER

30, 1983 -

MAY 16, 1984)

Parameter

Richmond

Lawson

Old-No. 8

Brick Plat

(mg/L, except as noted)

Portal

Mine Seep

Big Seep

Pit Bypass

Plow (gpm)*

277

pH (units)

0.6 to 1.4

1.6 to 2.8

1.7 to 3.1

2.2 to 3.1

2.3 to 4.6

Conduct iv i ty (Umhos/cm)

195,000

30,900

7,600

1,3S0

2,610

Temperature (*C)

26.5

20.4

16.2

9.9

11.7

Acidity (meq/L)

1,150

232

131

Aluminum

1,190

484

509

Antimony

0.295

<0.02

Arsenic

34.5

4.6

0.19

0.03

0.47

Cadmi um

10.1

2.4

0.46

0.05

0.41

Calcium

163

178

Chloride

Copper

184

120

12.9

14.4

Iron, total

13,000

3,560

1,270

141

369

Iron, ferrous

11,400

2,930

940

259

Lead

3.15

0.21

0.014

0.026

0.70

Magnesium

506

329

293

Manganese

13.5

9.0

11.9

0.44

1.8

Mercury (Ug/L

1.4

<0.1

0.1

<0.1

<0.2

Potassium

153

0.8

<0.3

0.5

Silica

23.8

15.0

18.9

2.6

8.1

Silver

0.014

<0.001

<0.008

<0.001

Sodium

112

6.1

3.3

3.0

Sulfate

60,100

13,400

6,800

690

1,530

Thallium

0.19

0.03

<0.01

Total dissolved solids

69,400

19,000

10,900

1,100

2,500

Total suspended solids

Zinc

1,440

350

48.9

4.8

in
•
V©

»!»>.,. mi.tmiiomi.nN nbffiirtetj at the time of sampling.

-------
- 13 -

Boulder Creek

The existing water quality in Boulder Creek is quite
variable and highly dependant on rainfall and the
operation of the existing Boulder cementation plant.
Boulder Creek water quality data is presented in Table 3.
The sources of contamination along Boulder Creek consist
of the following:

o Boulder Creek Cementation Riant

The Boulder Creek cementation plant receives acid mine
drainage discharge continually from the Richmond and
Lawson mine portals through a series of pipes and
flumes. Leaks and spills from the collection system
are additional minor sources of pollutant discharges.
The quantity of the discharge fro>a this plant is
dependent on rainfall, and the quality is dependent on
whether scrap iron is being maintained in the treatment
plant.

It is estimated that the discharge from the Boulder
cementation plant contributes approximately 20 to 40
percent of the copper, 90 to 95 percent of the cadmium,
and 90 to 95 percent of the zinc measured in Lower
Boulder Creek.

o Seeps

Numerous seeps exist along the Boulder Creek drainage.
The primary source of these seeps may be acid mine
drainage fro* the main orebody. Flows from these seeps
are greatly reduced during the summer months and some
may stop completely. The quality of these seeps is as
follows:

Parameter Range

pH 0.4 to 6.1 units

Cadmium, total 0.005 to 0.52 mg/1

Copper, total 1.0 to 13.4 mg/1

Zinc, total 0.3 to 59.7 mg/1

The percent contribution of seeps to Boulder Creek
is listed on Table 4.

-------
TABLE 3s Boulder Creek Water Quality

Parameter

pH, units

Cadmium, total, my/I

Copper, total, mq/1
Zinc, total, mg/1

Upper Boulder *
(Summer) (Winter)
Sept 1983 Dec 1983

Lower Boulder

6.8

0.012
<0.050
0.912

6.3

0.001
<0.050
0.020

(Summer) (Winter) (Spring)

Sept. 1983 Dec. 1983 May 1984

2.25 1.8

1.64 0.44 0.65

3.52 1.45 1.10

302.00 46.2 90.3

;

-------
o Tailings Piles and Waste Dumps

These sources contribute pollutants primarily during
storm events* In addition to dissolved metals and
acidic leachate, tailings and waste material are dis-
charged directly to receiving waters in violation of
federal suspended solids limitations and water quality
standards. The percent contribution of these soures
to Boulder Creek is listed on Table 4.

o Other Sources

Other sources of metal pollution probably consist of
subsurface drainage entering Boulder Creek and
dissolution of metal-bearing sediment in the creek.
These other sources of pollution are estimated to be
as follows:

Simmer Winter

Percent Percent

Metal lb/day Contribution lb/day Contribution

Copper 8.7 76 26 23

Cadmium 0.2 3 0 0

Zinc 31.0 4 30 1

b) Flat Creek

The only Identified source of pollutants discharged to
flat Creek is the Minnesota flats tailings pile. The
water quality of Plat Creek below Minnesota Flats is
given below.

Parameter

Average

Range

Flow
PH •
Copper
Cadmium
Zinc

280 gpm

1.32 mg/1
0.018 mg/1
1.92 mg/1

58 to 9,000 gpm
2.6 to 6.5 units
0.003 to 7.63 mg/1
0.002 to 0.050 mg/1
0.48 to 9.02 mg/1

c) Slickrock Creek

The existing water quality in Slickrock Creek is quite
variable and highly dependent on rainfall and the
operation of the Slickrock cementation plant. Slickrock
Creek water quality data is presented in Table 5. The
sources of contamination along Slickrock Creek consist
of I

-------
-m

- 16 -

TABLE 4

Percent Contribution of Boulder Creek
Seeps and Tailings Piles Waste Rock

Dumps

Metal

Cadmium

Copper

Zinc

Percent Contribution
Tlingil

§!!£»

0.1 - 3

3.1 - 17
0.1 - 3

Tailings Piles and
Waste Rock Dumps

0.1 - 7

0.7 - 20

0.1 - 4

-------
TABLE 5$

SIickrock Creek Water Quality

Parameter
pit, units

Cadmium, total, mg/1
Copper, total, mg/1
Zinc, total, mg/1

Upper Siickrock
(Summer) (Winter)
Sept If83 Pec 1983

6.9
0.001
<0.05

6.3
<0.001
<0.05
<0.01

Lower SIickrock

(Summer)

(Winter) (Spring)

Sept. 1983 Pec. 1983 May 1984

2.9
0.21
27.1
18.5

2.8
0.056

8.50
4.95

0.073
9.47
10.45

-------
o Slickrock Cementation Plant

The Slickrock cementation plant receives acid mine
drainage discharged continually from the Old-No. 8 mine
seep. The quantity of the discharge from the cementa-
tion plan is dependent on rainfall, and the quality is
dependent on whether scrap iron is maintained in the
treatment tanks. It is estimated that the discharge from
the Slickrock cementation plant contributes approximately
75 to 95 percent of the copper, cadmium, and zinc measured
in Lower Slickrock Creek.

o Seeps

A few seeps exist along Slickrock Creek. The primary
source of metals in these seeps appears to be from the
old slide area, and from the hematite pile. It is also
possible that the source of these seeps may be AMD from
the main orebody. The major contributing seep is Big
Seep. The source of the seep area is groundwater and
surface water migrating through an old waste rock dump.
The quality of the Slickrock seeps is as follows:

Parameter (mg/1)

pH 2.7 to 6.5 units

Cadmium, total 0.001 to 0.30 mg/1

Copper, total <0.050 to 42.6 mg/1

Zinc, total 0.01 to 24.8 mg/1

Flows from the seeps are greatly reduced during the
summer and some may completely stop. It is estimated
that these seeps contribute 2 to 25 percent of the
metals in Slickrock Creek.

o Tailings Piles and Waste Dumps

The sources along Slickrock contribute pollutants both
during storm and normal rainfall events. The hematite
pile along Slickrock Creek contributes about 1 percent
of the metals in Slickrock Creek.

o Other Sources

The other sources of pollution along Slickrock Creek
are the Brick Plat Bypass that flows down the mountain
and enters the creek, subsurface drainage, and dissolution
of metal-bearing sediment in the creek. It is estimated
that these sources can contribute up to 5-30 percent of
the metals in Slickrock Creek depending upon the time
of year in which the discharges occur.

-------
19 -

d) Spring Creek

. The existing water quality in Spring Creek is presented
on Table 6* The source of contamination in Spring
Creek have been described in the Boulder Creek and
Slickrock Creek sections.

In addition* there are probably sediment deposits within
the streambed, as observed along Slickrock Creek, which
also contribute to metals pollution.

It is not possible to fully assess the metal contri-
bution of the sediments, but it is estimated it is
relatively minor in relationship to the contribution
from Boulder and Slickrock Creeks.

e) Keswick Reservoir and Sacramento River

The source of contamination in Keswick Reservoir are
inflows from Flat Creek and Spring Creek and sediments
deposited within the reservoir. The average water
quality in the Sacramento River is presented in Table 7.

The Sacramento River above Keswick Reservoir already
contains metals as shown in Table 7. After Flat Creek and
Spring Creek enter the river in Keswick Reservoir, the
concentration of metals are elevated up two to three
times. Due to the relative low concentrations of metals
and the variable flows from Keswick Reservoir, it is not
possible to accurately estimate the metals contribution
from Flat Creek and Spring Creek.

3. Environmental Impacts

Due to past and continuing releases of AMD to receiving
waters, Boulder Creek, Slickrock Creek, Flat Creek and portions
of Spring Creek are essentially devoid of aquatic life. During
the RI, between 1,143 and 3,695 pounds per day of copper, zinc,
plus cadmium were carried from the site into the Spring Creek
Reservoir. Of this total, between 623 and 3,328 pounds per day
of copper, zinc and cadmium were discharged into the Sacramento
River. These releases occurred over a period that is best
characterized as relatively dry winter conditions. The above
totals can be expected to rise significantly during normal or
above normal rainfall conditions.

Off-site, subsurface migration of contaminated groundwater
does not appear to be a problem at this site. The hydraulics of
the site are such that the mine workings act as a drain., drawing
groundwater towards the mountain, and discharging it into adjacent
surface waters.

-------
TABLE 6: Spring Creek Water Quality

ABOVE IRON MOUNTAIN

BELOW IRON MOUNTAIN

Parameter Average

pH (units)

Cadmium, total, mg/1
Copper* total, mg/1 0.06

Zinc, total, mg/i 0.12

Range

4.5 to 7.8
<0.001 to 0.001
0.03 to 0.10
0.07 to 0.15

Average

0.10
1.94

12.5

Range

2.4 to 3.2
0.03 to 0.16
0.97 to 2.74
3.25 to 17.4

H
O

-------
Table 7

SUMMARY OF SACRAMENTO RIVER MONITORING

FEBRUARY 2, 1984, THROUGH JUNE 24, 1984
(Average of Detectable Values)*

Parameter
(Uq/L, except as noted)

Sacramento
River Below
Shasta Dam

Sacramento
River Above
Spring Creek**

Sacramento
River Below
Keswick Dam

Sacramento
River at
Redding Intake

Sacramento River
Below Keswick Dame
Average Range

pH (range of units)

6.4 to 8.1

6.5 to 8.2

6.3 to 8.1

6.3 to 8.0

Conductivity (imtios/cin)

—

«—

Temperature

9.6

10.2

9.9

10.3

—

Carimiun, total

0.10

0.29

0.55

0.23

—

Cadmium, soliiile

0.18

0.29

0.41

0.37

2.5

1.8 to 4.0

Copper, total

3.5

6.5

8.5

15.8

—

Copper, soluble

3.7

4.6

4.8

4.9

10 to 52

Iron, total

224

339

505

470

—

Iron, soluble

—

Sulfate (mg/L)

3.7

4.6

5.2

6.3

—

Zinc, total

14.8

24.6

37.0

37.4

—

Zinc, soluble

13.0

26.3

30.8

39.8

196

23 to 500

aonly values reported above the detection limits were averaged.

bsanpling site appears to be influenced by backeddies from Spring Creek.

concentrations monitored ty WDCB during three spill events at Spring
Creek Re setv«jit—Januaty 1978# January 1983, and March 1983.

Note: No identifiable reasons for hii^er soluble concentrations compared to
total concentrations ot some constituents.

-------
4. Impacts on Aquatic Life

a) Introduction

While the occurrence of toxicity has been documented in the
Sacramento River, it is extremely difficult to quantify the
extent of the loss in a river the size of the Sacramento. The
fishkills occur during the wet season when the waters are typically
muddy. Even with clear water, the river is difficult to survey
with widths as great as 300 feet, depths a.s great as 35 feet, and
fast currents that carry dead fish downstream. The most difficult
mortalities to observe in the river are the fish most sensitive
to metal toxicity - the early life stages of salmon and steelhead.
These sensitive salmonid lifestages live underneath the gravel as
small "sac fry" or in the river as small 2-inch "swim-ups" that
have emerged from their nests.

In addition to the occurrence of lethal toxicity, there are
more frequent occurrences of sublethal toxicity that could act to
reduce the overall productivity of the population. Effects such
as reduced growth rates, physiological problems, and diminished
immune response are known to occur due to exposure to heavy
metals. In a recent report to the U.S. Bureau of Reclamation,
the U.S. Fish and Wildlife Service estimated that the monetary
value of the Chinook salmon and steelhead trout runs produced
upstream from the Red Bluff Diversion Dam is approxmately $33.7
million annually. In addition, the economic value of these
fishery resources, with attainment of fishery management goals,
is anticipated to increase to $72 million annually.

b) Discussion

Valuable fisheries resources, including migratory popula-
tions of salmon, steelhead and resident populations of trout in
the Sacramento River are significantly impacted by the AMD from
the Spring Creek basin and have experienced numerous instances
of above normal mortality over the last 46 years. These incidents
which, have been directly attributed to AMD from Iron Mountain
Mine were the result of observed mortality of adult fish in the
Sacramento River and calculated mortality of eggs and fry on the
basis of copper, zinc, and cadmium levels measured in the River
below Keswick Dam. Table 8 was developed by the California
Department of Fish and Game (CDFG) and lists the documented
fishkills. CDFG has indicated that the Fall run of Chinook
salmon in the upper Sacramento River has ranged from an estimated
high of 400,000 in 1953 to a low of 22,000 with an average decline
of 87 percent in the last 20 years; that the average run of
salmon over a 20 year period showed a decline from 275,000 to
75,000 salmon. This decline is attributed to several causes
including AMD from Iron Mountain Mine.

-------
22 -

4. Impacts on Aquatic Life

a) Introduction

While the occurrence of toxicity has been documented in the
Sacramento River, it is extremely difficult to quantify the
extent of the loss in a river the size of the Sacramento. The
fishkills occur during the wet season when the waters are typically
muddy. Even with clear water, the river is difficult to survey
with widths as great as 300 feet, depths as great as 35 feet, and
fast currents that carry dead fish downstream. The most difficult
mortalities to observe in the river are the fish most sensitive
to metal toxicity - the early life stages of salmon and steelhead.
These sensitive salmonid lifestages live underneath the gravel as
small "sac fry" or in the river as small 2-inch "swim-ups" that
have emerged from their nests.

b) Discussion

-------
TAILS#

ROLUMtltTIB OCCBRRENCtf Of ULIKM AND 1H0UT MORTALITIES M TW SACRAMENTO RIVER ATTRIMntS TO RIAfT METAL POLLUTION FROM SMtlMC CREEK DRAINAGE

MASTA COUWn

Tnw of HarullHw Ohwtw< RaWr Ratlaatad
SalaM Trout of Mortailtlaa NtaiWr of

Caantai

tkatrvM 1m __________

Ucatlti AJwIt JwhIU Mult JNtclh

CaMtt tMlKM
Vaata PIU

¦¦11a Parry

Rails Parry
¦alia Parry

taawtck Dm

RaMlat Area
RaMlac Araa

UakwMM

200

Martalltiaa

SOS of
apawlaR raa

Matteai of
OkMrratlM

Conditio** la
Sacra—to llyf
Hw (cfa> Clarity

¦acraaaata Rlrar tola* Kaawlek
NaalMo Natal Coocaotratloaa

a
a

¦nairaia
42

apat ahaarvatlaa

MatraM ca|a taata

iMfwt Ma alia af Ink

apat afcaat»atlaaa

Kaawlek Plate Trap aai
bloaaaay af Rprlac CHi
wator

apat akaarvafelM

•pat aiMrvatlM

3,000

5,000

4,000

27,000 mmttf
J, 500

SME5£

O.Oit

Ant*}

Zlac .

0.04

0.i»

taMlag Atm
RaMta| Arpa
RaMlaa Araa

Raiilac iraa

25
250
25,000

¦nay § altaa aff

2,400 a*My
2,400

12,000 weUf
9,500

-------
TABLKf

mencnn oGcatiunccs or salmon and mm mortaliths m m sacrammto tivn ATTtiwro to mum nral rotumoo im iniK cam boainaci

MASTA GOONTT

at*

Tim of H»tUI1U«i Otwfrwl M« Batlaatai
akwrattM tmlmom Trout of Martallttaa taWr af

Cawata4 Hittdltit*

Uc*t(M

Adult JmwIU Aiwlt Jwwllt

Natliai af
OkMrvitlta

1940

ItMtt •atlut
Kmc* ru«

i/u mil r«rcr

IJ" Ball* farry

1/49

l»SS

1/12

l»S»

2/21
I9S4

1/19
ItSI

##•»

its?

«/i§-
t/s?

12/24
19S?

>9/2*-
I0/S7

¦•lit Parry

R*44l«| Area
l«Mtek

¦•Mint Arc* *
¦aMlat Area

Milni Araa
kMli| Ar#a
Mlli« Am
BaMlag Area

200

naiaM

¦aairaia
42

MX •(
apaaalat raa

Oakaawa

250

25,000

Caailtlaaa la

apat aWarwatloa

Bitrwa cat* taaia

Inapact mm af

a pat afcaarvatlaaa

Raaviek flak Trap mm4
felaaaaay af Sprtas Crh
aatar

apat afeaarvattaa

a pat akaarvatlaa

Sacraaaata Rlvar
flaw (cfa) Clarity

1,000

Sacraaaata llvar Bala* Kiwlek
Maalma Natal Caaeaatratlaaa

Js£12_

.— awrvay S allaa af

5,000

4,000 aaMy

27,000 saMy
1,500

2,400 miAy
2,400

12,000 aaMy

7,900 aaMy

Cappat

0.041

flac,

0.04

0.1)

rv>

-------
According to the CDFG, the decline of the upper Sacramento
River salmon and steelhead stocks represents a sizeable economic
loss to the state due to the lost availability of these fish to
the commercial and sport fishery. At times, the upper Sacramento
River produced half of the state's Chinook salmon. Economic
studies conducted by CDFG and the U.S. Fish and Wildlife Service
have estimated that the continuing economic losses associated
with the present depressed population levels of salmon and steel-
head relative to the catch levels in the past have a net annual
economic value ranging between $30-$40 million. CDFG believes
that the incremental mortality caused by discharges from Iron
Mountain Mine are responsible for a significant share of that
economic loss.

Of particular concern is impact of AMD on populations of
winter run chinook salmon, one of four genetically distinct
populations of salmon in the river. According to the CDFG, the
winter run population in the upper Sacramento River has declined
precipitously in the past 20 years to the point where the National
Marine Fisheries Service is evaluating a petition requesting
that the winter run chinook be listed under the Endangered Species
Act of 1973. The CDFG has apprised EPA that one of the priority
actions that would be included in any winter run restoration or
recovery effort is correcting the heavy metal pollution problem
caused by Iron Mountain Mine. Additionally, the king salmon
runs in the upper Sacramento River have experienced a 50 percent
decline over the past 30-35 years, with heavy metal pollution
from the Spring Creek basin being cited as one of the major
responsible factors.

Because of the variations in the operation of the Shasta
unit (Shasta Darn, Keswick Dam, Spring Creek Debris Dam, and the
Spring Creek hydroelectric power plant), and unusual climatological
conditions, there has not been any long-term undiluted spills and,
thus, no observed mortality of adult fish in the Iron Mountain
Mine area since 1969. There is, however, a shared concern among
state and federal regulatory agencies that as competition for
Shasta Lake water increases in the future, the U.S. Bureau of
Reclamation may be held more accountable for ensuring that only
the authorized uses of the water are allowed; this could result
in the lack of adequate dilution water being made available to
avert fishkills.

5. Potential Public Health Impacts

The degree of human risk associated with the AMD from the
Iron Mountain Mine site depends on the nature and extent of
exposure. The California Department of Health Services (Depart-
ment), in an endangerment assessment prepared on August.22, 1984,
for this project, discussed the types of exposure that represent
a potential threat to public health. These included the following:

-------
41

• 26 -

Dermal Contact^ Near its source, the AMD contains sulfuric
acid in concentrations that could cause serious eye injuries
and skin irritation through direct exposure. Although the
study area is located in rugged and remote terrain, the
potential for human exposure cannot be ruled out. The area
is located between two heavily used National Forest areas.

Areas adjacent to the nine property are frequently used for
recreational purposes, especially for off-road vehicle use.
The mine owners have complained of trespassing and vandalism
problems on the site. The MID is diluted as it enters Boulder
Creek and Slickrock Creek and there is a less serious risk
with regard to dermal contact with increased distance from the
source•

Ingestion of Watert The potential for direct ingestion of AMD
in the upper study area is considered small for two reasons *
a) once the AMD enters the creeks, there is a discoloration
associated with the precipitation of iron, and b) the remoteness
of most of these areas limits access.

Cadmium concentrations measured at the Redding raw water intake
have not exceeded the drinking water standards. A potential
public health threat does exist due to the elevated concentra-
tions of metals in the Sacramento River. Levels of cadmium in
the River have approached and occasionally have exceeded the
proposed EPA drinking water standard of .005 mg/1.

Ingestion of Fish* Ingestion of fish taken from Keswick Reservoir
does not appear to represent a significant public health threat
according to an analysis which expanded the endangerment assess-
ment prepared by the Department of Health Services* However,
the Department indicates that the long term risk from the
bioaccumulative toxin, cadmium, should not be underestimated.
The Department estimates that 50 percent of the body burden of
cadmium is located in the liver and kidney of fish, with another
50 percent distributed across other tissues. Humans also
accumulate cadmium in the liver and kidneys over their lifetime.
It is felt that, without remediation, mine effluent will continue
to be deposited in sportfishing areas of the Sacramento River
and the concentration of cadmium in fish will continue to be
elevated above normal levels.

6. Impacts on Public Welfare

Shasta Dam was constructed under the authority of Public
Law 84-386, as part of the Trinity River Division, Central Valley
Project. This law created several specific uses of Shasta Lake
water, including the generation of hydroelectric power, water
sales to farmers, and use as a drinking water supply. 'Shasta
Lake also has a recreational value associated with tourism,
boating, fishing, and swimming.

-------
•i(.i

- 27

Release of Shasta Lake waters for pollution control in the
Iron Mountain Nine area is not an authorized use o£ these waters.
Nevertheless, since the construction of the Shasta Dam/Keswick
Dam/Spring Creek Debris Dam water management system, Shasta
Lake waters have been, and continue to be released for this
purpose, when waters can be provided without adverse impacts to
other project requirements. By controlling the release of these
waters the U.S. Bureau of Reclamation (Bureau) has assisted
other federal and state agencies, in promoting fishery resources
in the Sacramento River*

Although it is difficult to quantify the exact value of
Shasta Lake water, the Bureau has estimated the revenue that
would be lost by releasing Shasta Lake water for pollution
control. This was accomplished through the use of a mathematical
water model that assumed that water that wasn't being released
for pollution control would be sold for municipal and industrial
purposes. Based on the Bureau's analysis, it was estimated that
meeting less stringent standards (the original water quality
standards that were in effect prior to the state adopting the
existing water quality standards) in the Sacramento River would
result in an annual loss in revenue from the U.S. Treasury of
about $32 million, and that fish saved by releasing this additional
dilution water would have an annual value of $1.4 million. Meeting
the proposed Superfund metals levels, which are substantially
lower, would cost about $456 million in dilution releases, with
fish savings of about $9.6 million per year. Without remediation
in the form of source control and treatment, releases of Shasta
Lake water will be required until such time as Iron Mountain
Mine ceases to discharge AMD.

V. ENFORCEMENT ANALYSIS - Confidential
(See Attachment)

VI. ALTERNATIVES EVALUATION

A. Introduction

The major objective of the feasibility study was to evaluate
remedial alternatives using a cost-effective approach consistent
with the goals and objectives of CERCLA. A cost-effective remedial
alternative is defined in the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) 40 CFR 5300, et.seq. as the
alternative that effectively .nitigates and minimizes threats to
pnd provides adequate protection of public health and welfare and
the environment. Except as provided in Section 300.68(i)(5),
this requires the selection of a remedy that attains or exceeds
applicable or relevant and appropriate federal public health and
environmental requirements that have been identified for the
specific site. In selecting the appropriate extent of remedy,
EPA is directed to consider cost, technology, reliability,
administrative and other concerns, and their relevant effects on
public health and welfare and the environment.

-------
The feasibility study process included the following steps:
(1) identification of general response actions, (2) identifica-
tion of target clean-up levels, (3) assembly of the universe of
technologies relevant to the response actions, (4) retention of
the surviving technologies as component actions, (5) assembly
of the component actions into combined alternatives, (6) initial
screening of the combined alternatives, and (7) detailed analysi
of surviving combined alternatives. Nine combined alternatives
(CA-1 to CA-9) underwent very detailed analysis. Three alterna-
tives were considered in less detail and were included in the
final alternatives matrix: Alternatives CA-10 ($1.4 billion),
CA-11 ($350 million) and CA-12 ($263 million). The feasibility
study results are presented in more detail in the following
paragraphs.

Based on site background information and the nature and
extent of the problems from the technical investigation to date,
the key general objectives for the Iron Mountain Mine site were:

. To minimize off-site contaminant migration via surface
water runoff and seepage, and

To mitigate impacts and minimize the migration of
contaminants that have already moved from the site
through receiving waters.

The two areas targeted for remediation and selected general
response actions were:

Areas of Remediation

Ore bodies and underground
mine workings

Surface water

General Response Action

No action, recovery, treatment
source control, and disposal

No action, water management,
treatment, and disposal.

The contaminants of primary concern at the Iron Mountain
Mine site are copper, cadmium, and zinc because: a) these
contaminants have been detected at high levels at the source and
in surface waters receiving discharges from Iron Mountain Mine,
b) acute dosages of these contaminants have been found to result
in fish kills; sub-lethal impacts have, among other things,
resulted in reduced rates of growth and accumulations of metals
in fish tissues; and c) even when toxic levels are not reached,
these metals act to depress the overall productivity of life in
Keswick Reservoir and the Sacramento River.

-------
- 29

B. Site-Specific Action Levels

Three sets of target clean-up levels were considered as
primary cleanup objectives for Iron Mountain Mines

1. Implement remedial actions to achieve the following CPA

Water Quality Criteria for Protection of Aquatic Life below
Keswick Oam:

Copper* 5.4 ug/1
Zinc: 47.0 ug/1;

Cadmium: 0.55 ug/1

2. Meet Regional Board Basin Plan Objectives for copper,
cadmium and zinc in the Upper Sacramento River:

Copper: 5.6 ug/1
Zinc: 16.0 ug/1;

Cadmium: 0.22 ug/1

These objectives are based on a series of intensive studies
conducted by the CDF6. According to CDFG# implementation
of remedial activities that meet these objectives would
provide safe levels having no chronic or acute effect on
aquatic life in the Upper Sacramento River.

3. Meet background levels (established by the water quality

upstream of the confluence of Spring Creek and the Sacramento
River):

Copper: 3.5 ug/1
Zinc: 14.8 ug/1
Cadmium: .1 ug/1

The secondary objective is to reduce the metals loading from
the Iron Mountain Mine site to receiving waters.

C. Technology Development

A variety of technologies was examined with regard to
technical feasibility# degree of public health protection
afforded, environmental impact# institutional concerns# and
cost.

The applicable technologies identified were then combined
to form remedial action alternatives that addressed source control
and treatment of AMD at the mine and surface water management.

-------
14,

- 30 -

Preferred technologies for the various components that
addressed source control and water management are identified in
Table 9.

O. Components for Detailed Analysis

The following discussion describes the components that were
later combined into alternatives (see Table 10). Table 11
presents the technical, environmental, institutional and other
considerations for each of the components (#1 through til).

Component ~!. Solution Mining (Proposed bv IMMI)

Toward the end of the RI/FS, Iron Mountain Mine, Incorporated
(IMMI) submitted a concept for a proposed metals recovery operation
at Iron Mountain Mine. This proposal was developed independent
of EPA's feasibility study by consultants for IMMI. This proposal
included the in situ leaching of the sulfide orebody to extract
copper, zinc, iron, and precious metals, and the recovery of the
base metals as industrial and agricultural chemicals.

The basic principle of the IMMI proposal is to seal the
Richmond and Lawson portals, recirculate AMD back into the
mountain and draw off 2,000 gpm of concentrated acid mine water
from in situ leaching, and treat it at a copper extraction plant.
An acidified 1,800 gpm stream would be recycled for reinjection
into the orebody to enhance metal leaching. A 200 gpm bleed
stream is treated in the metal salts recovery plant and a waste-
water treatment plant prior to discharging to receiving waters
or irrigation.

Component 12. Partial Capping

The purpose of capping and constructing drainage ditches
around cracked and caved ground areas above the Richmond orebody
is to reduce the water available for generation of AMD by inter-
cepting surface water and directing it away from the orebody.

This source control method is applicable primarily to the Richmond-
Complex orebody as this is the only source that shows significant
contribution from surface water inflow. Cracked ground, caved
ground, and other known primary conduits for inflow would be
surface-plugged and sealed to reduce the rapid inflow of water
into these areas. Surface water would be intercepted by a system
of lined ditches and directed away from the orebody to reduce
the potential of surface water finding a path of rapid inflow.

-------
'II.

-31-

Tatde 9. Available Technologies

General Response
Action

Technologies

OREBODIES AND MINE
WORKINGS

No Action

Recovery

Treatment

Disposal

No action

Mine the orebody using open pit,
underground, or in situ methods

In situ methods without metals
recovery, and the use of sur-
factants or other inhibiting agents
groundwater'barrier walls, ground-
water interception, pumping, and
revegetation of disturbed areas.
Injection of Low-density concrete
in underground mine workings.

Landfill

SURFACE WATER
No Action
Water Management

Treatment

Disposal (AMD)

Disposal (Solids)

No action

Transbasin stream diversion (pipe,
open channel, flume), local stream
diversion, enlarge existing
storage, construct new storage, and
modify CVP operating plan

Precipitation (utilizing lime/
limestone, sodium hydroxide, soda
ash), biological neutralization,
bogs, sulfide precipitation, starch
xanthate treatment, clarifier
thickener, aeration, chemical
oxidation, biochemical oxidation,
electroflocation, ionic flotation,
carbon adsorption, solvent
extraction, sodium aluminate, copper
cementation, electrowinning, filtra-
tion, ion exchange, reverse osmosis,
electrodialysis

Solar evaporation, deep well injec-
tion, controlled release, and deep
water injection

Landfill (on or offsite), solids
disposal in mine workings

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4't.l

-32-

Table 10. Tbmponents for Detailed Analysis
SOURCE CONTROL

• Partial capping

• Complete capping

• Groundwater interception

• Injection of Low Density Cellular Concrete in

underground Mine Workings

TREATMENT

• Treatment of the three major sources

• Treatment of the five major sources

° Treatment of five major sources and other sources
in Slickrock Creek

• Treatment of the five major sources plus other

sources in Slickrock Creek and Boulder Creek

WATER MANAGEMENT

• Diversion of upper Spring Creek to Flat Creek

0 Diversion of South Fork Spring Creek to Rock
Creek

• Enlargement of Spring Creek Debris Dan

• Diversion of Upper Slickrock Creek

around tailings piles

-------
TABUS 11

Itechnlcal, Environmental and Institutional Considerations for Remedial Action Components

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-------
TABLE 11

9l^mm Technical, Environmental arid Institutional Considerations for Remedial Action Components

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TABLE 11

Technical, ftivirormental and Institutional Considerations Top Remedial Action Components

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-------
'14: I

- 36

The caved ground areas would be filled and sloped to maximize
runoff. A total of five caved ground areas would be filled;
this will require a total fill quantity of approximately 40,000
cubic yards of material. To reduce vertical infiltration
into caved ground areas, the areas would be filled and graded to
drain using a filter material and low permeability layer.

Component »3.' Complete Capping

This component involves capping approximately 15 acres
overlying the Richmond orebody. The alternative would require
stripping and grubbing of some of the existing vegetation,
filling of the caved and cracked ground, some regrading of the
site to limit slopes where possible, and construction of benches
to divert water to adjacent drainages. A soil-cement surface
barrier would then be applied to the area.

The six caved ground areas, totaling approximately 2 acres,
would be filled with cobble- to sand-sized materials prior to
applying the soil-cement. Two cracked ground areas would be
filled with a slush-type grout and cobble- to sand-sized
materials, with a low-permeability seal at the ground surface.

The lower portion of Brick Flat Pit would be filled similar
to the caved ground areas to allow gravity drainage of water
from the pit area.

Interception ditches and drains would be provided to intercept
surface water and divert it away from areas where the orebody is
exposed to surface runoff.

Component #4. - Ground Water Interception

In this component, groundwater moving toward the Richmond
orebody would be intercepted by a tunnel and drill holes on
either side of the orebody. Through gravity flow, the water
would then be conveyed to Boulder Creek. Approximately 1,250
feet of the existing Richmond tunnel would be rehabilitated and
used as the access tunnel for constructing the two new tunnels
on either side of the orebody. These new tunnels would be
approximately 7 feet in diameter and 1,600 feet in length.

A vertical system of drilL holes would be installed
approximately every 50 to 100 feet along the two new tunnels and
would act as groundwater interceptors.

Component t5. Injection of Low-Density Cellular
"Concrete Into Underground Mine Workings

This component consists of filling the underground mine
workings (UMW's) with a low-density cellular concrete (LDCC) to
eliminate or reduce the formation of AMD. This objective could

-------
37 -

be met by LDCC injection if exposed ore could be sealed in the
UMW's or if discharge could be reduced sufficiently to raise the
groundwater table above the orebodyr thereby minimizing available
oxygen for the formation of AMD.

In developing this component, it was assumed that a concrete
batch plant and materials storage facility would be constructed
near the Richmond portal. Stockpiled at the site would be cement,
chemicals for producing a low-density concrete (this chemical is
a foaming agent which causes the concrete.-to expand and therefore
reduces its density), and aggregate. The aggregate for the LDCC
would be composed of Minnesota Flats tailings, available onsite
hematite material, and waste rock and slide material from the
Big Seep. This would reduce the cost for aggregate material and
also reduce existing sources of surface runoff pollution. Hater
containing AMD would be conveyed to the batch plant, where it
would be neutralized and used in the manufacture of the LDCC*

As the LDCC is produced, it will be pumped into the mine
workings and allowed to solidify. This is intended to coat the
exposed ore and plug the UMW's, which could bring the water
table back to historical elevation, and eliminate or reduce AMD
formation. Rehabilitation of the Richmond workings would be
required to provide access needed to effectively inject the LDCC.
Rehabilitation of the Hornet workings and others may also be
necessary.

It is expected to take two years, operating 24 hours per
day, to fill the workings with LDCC.

Component #6. Treatment

* Sub-Component € (a) Treatment of AMD from Three
Major Sources

This component consists of collecting AMD from the Richmond
portal, Lawson portal, and Old No. 8 seep, and conveying it to a
lime/limestone treatment plant for treatment. This component
assumes that the sludge produced from the treatment plant would
be dewatered and taken to Brick Flat Pit (BFP) for disposal.

It is estimated that BFP can accomodate dewatered sludge produced
by treating the three major sources over a 30-year period.

For ease of transporting sludge to BFP, the lime/limestone
treatment plant would be sited at the old processing facility
near the Richmond portal. AMD from the Old No. 8 seep may or
may not have to be pumped to the treatment plant, depending on
final site layout and elevations.

BFP would be modified with an embankment to provide storage
of the sludge produced from the treatment process. The walls of
the pit would be coated to form a relatively impervious liner.

-------
- 38

In conjunction with the treatment plant construction and
modifications to^BFP, road improvements to these sites will have
to be constructed.

•Sub-Component 6 {b) Treatment of AMD from Five Major

Sources of Pollution

AMD from the five major sources (Richmond portal* Lawson
portal, Big Seep, Old No. 8 seep, and Brick Flat Pit diversion)
would be collected and transported by gravity to the treatment
plant. The maximum flow for this alternative is estimated to be
4,000 gpm. The expected overall removal of metals leaving the
site with this alternative is 72 percent of copper and 86 percent
of zinc and cadmium.

Small diversion structures would be constructed at Big Seep
and the Brick Flat Pit diversion. Flows from these five sources
would be combined into a PVC pipeline, which would be buried
along the route of the existing access road and transported
approximately 9 miles to the treatment plant located on 90 acres
of land immediately adjacent to the Sacramento River.

The neutralization treatment process consists of the follow-
ing units:

1. The addition of limestone to the AMD to increase the
pH to 4.

2. Fifteen acres of first-stage settling lagoons to remove
sludge.

3. The addition of lime to raise the pH to 8.5. The
addition of air for the oxidation of soluble ferrous
iron to insoluble ferric iron.

5. A heavy solids separator, together with 14 acres of
second-stage solids lagoons for sludge removal.

The lagoons would be designed to allow the sludge to dry
during the summer months. The remaining solids would then be
hauled to either a Class I or Class II landfill constructed
adjacent to the treatment plant.

•Sub-Component 6 (c) Treatment of AMD from Five Major
Sources Plus Other Slickrock Sources

The component is essentially the same as Alternative 7 (b)
with the exception that the sources on Slickrock Creek will also
be collected and treated with the five major sources.

-------
41

The collection system on Slickrock Creek would consist of
an upper diversion dam which bypasses clean water around the
reach of the creek that is impacted by the other sources including
seeps, slide debris, and tailings piles.

A second diversion dam would be constructed downstream of
the other sources to collect the flow from Big Seep* Old No. 8
Mine seep, and Brick Plat Pit diversion, together with the other
sources. This AND would flow by gravity and would be combined
with the piped flows from Richmond portal.-and Lawson portal.
The combined flow would then be routed to a lime/limestone
treatment plant.

The maximum hourly flow for this alternative is estimated
to be 42,000 gpm under 1978 conditions. This would require that
the transport pipeline and limestone and lime treatment structures
be enlarged above those estimated for Alternative 5. The size
of the sludge lagoons would remain approximately the same. The
expected overall removal of metals from the site with this alter-
native is 86 percent of copper and 93 percent of zinc and cadmium.

• Sub-Component 6(d) Treatment of AMD front the Five
Major Sources Plus Other Boulder and Slickrock
Sources

With this component, the five major sources and all other
sources on Boulder Creek and Slickrock would be collected and
treated. Upper diversion dams would be constructed on both
Slickrock and Boulder Creeks to divert clean water around the
areas of the creeks that are being contaminated by the other
sources.

Downstream diversion dams would be constructed to capture
and divert the remaining flows in the streams. The flows would
be combined and would flow by gravity to the treatment plant.

The maximum hourly flow for this alternative is estimated to
be 110,000 gpm under 1978 conditions. As with Alternative T-lb,
this will require increasing the size of the pipeline and the
treatment plant structures. It is expected that the overall
removal of metals from the site with this alternative would be
essentially 100 percent.

• Sub-Component 6 (e) Treatment of AMD from the
Three Major Sources with Copper Cementation

With this component, the three major sources of pollution
(Richmond portal, Lawson portal and the Old No. 8 mine seep)
would receive copper cementation treatment. Copper cementation
is an oxidation-reduction reaction whereby solvated (in solution)
copper ions are exchanged for elemental iron (usually provided
as scrap iron). This scrap iron, preferably well shredded to

-------
ifcl

- 40

obtain good contact with the liquid wast* stream, is placed in a
basin large enough to produce fairly quiescent conditions. As
the wastewater is passed through the basin, iron is dissolved
into the stream and a copper sludge settles out. This process
is currently being practiced at Iron Mountain Mine and is achieving
good recovery of copper (as high as 95 percent plus removal in
one of the cementation plants).

Component »7« Diversion of Upper Spring Creek

This component would reduce flow into SCDD by diverting
upper Spring Creek to Flat Creek. A 16-foot-high, 100-foot-
long, rock-filled diversion dam would be built on Spring Creek
near Minnesota Flats to divert up to 800 cfs of flow.

An 8-foot-diameter tunnel, with a hydraulic capacity of
approximately 800 cfs, would be constructed on the upstream side
of the dam to divert the flow into the Flat Creek watershed.
The length of this tunnel would be approximately 600 feet. A
chute and energy dissipator would be constructed between the
diversion and the point of discharge into Flat Creek.

Component *8. Diversion of South Fork Spring Creek

This component would reduce flow into SCDD by diverting the
South Fork of Spring Creek (SFSC) to Rock Creek. To accomplish
this, a 10-foot-high, 60-foot-long diversion structure would be
built on SFSC. About 4,000 feet of 54-inch conduit would
carry the diverted water to Rock Creek. The hydraulic capacity
of the diversion system would be 250 cfs.

Component 19. Enlargement of Spring Creek Debris Dam

The existing Spring Creek Debris Dam would be enlarged at
its present site. The present storage capacity of the dam is
5,800 acre-feet. This would be increased to a volume of between
7,000 acre-feet and 23,000 acre-feet depending on which cleanup
objective is selected.

Component #10. Upper Slickrock Creek Diversion Around
Tailings Piles

The purpose of this diversion is to reduce the volume of
flow from the Big Seep pollution source. It is believed that as
Slickrock Creek flows over and through the pile of slide debris
that fills the canyon above the Big Seep area, a significant
portion of the flow enters the loose slide material and reappears
in the Big Seep area. Analysis of the Big Seep hydrograph has
led to the conclusion that a significant reduction in the flow
and pollution load from Big Seep could be achieved by intercepting
and diverting Upper Slickrock Creek before it comes into contact
with the slide debris.

-------
II

- 41 -

This component would involve a diversion structure, an
18-inch PVC pipeline, and an energy dissipator at the end
of the pipeline. Upper Slickrock Crek flow would be diverted
around the slide area to the lower reach of Slickrock Creek.

A numerical water quality model was used to determine
if any of the individual components could achieve either
California Basin Plan Objectives or EPA Water Quality Criteria
for Protection of Aquatic Life below Keswick Dam. The model
used a mass balance approach to account for heavy metals as
they are carried in the streams (Boulder Creek, Slickrock
Creek, and Spring Creek) through Spring Creek Reservoir and
eventually to Keswick Reservoir. The model regulated discharges
from Spring Creek Reservoir such that when the discharge is
mixed with Sacramento River water released from Shasta Lake,
water quality objectives are met below Keswick Dam.

The results from the operation of the model indicated
that the aforementioned components generally could not achieve
either set of water quality objectives below Keswick Dam (or
points upstream) if implemented individually. There are two
exceptions, however. Conceivably, the Spring Creek Debris
Dam could be enlarged to such a size that the objectives
could be met through flow equalization alone. Or, the
objectives could be met by using the Spring Creek Reservior
as a collection basin and treating all liquids in it by lime'
neutralization. This latter approach could achieve background
levels for metals below Keswick Dam at an estimated cost of
$263 million. Treatment of the liquids in the Spring Creek
Reservior will be carried forward as an alternative. Varying
the capacity of the Spring Creek Reservior by varying the
height of the dam will be carried forward as a component of
many of the alternatives to be considered. It was felt that
varying the size of the Spring Creek Debris Dam should not
stand alone as an alternative because this would provide only
dilution of the AND, with no source control or treatment and
with no reduction of total metals loading into the Sacramento
River.

E. Description of Combined Remedial Action Alternatives

The previously described components were assembled into
. combined alternatives for more detailed analysis. Nine alterna-
tives (CA-1 through CA-9) underwent very detailed analysis.

Three more alternatives (CA-10 through CA-12) underwent a less
detailed analysis. The proposal submitted by the site owner to
establish a solution mining operation at the site was screened
out in the Feasibility Study because it had not been developed to
the point where EPA could determine the technical feasibility and
economic viability of the project. In addition, the project did
not demonstrate compliance with all applicable, relevant and
appropriate federal and state requirements, and a site closure
plan had not been developed.

-------
- 42 -

The remedial action alternatives evaluated in the Feasibility

Study and the Addendum to the Feasibility Study are:

(CA-1) Diversion of upper Spring Creek to Flat Creek, diversion

of South Fork Spring Creek to Rock Creek, complete capping
above the Richmond Orebody, groundwater interception,
and copper cementation.

(CA-2) Diversion of upper Spring Creek to Flat Creek, diversion

of South Fork Spring Creek to Rock Creek, complete capping,
groundwater interception, and treatment.

(CA-3) Diversion of upper Spring Creek to Flat Creek, diversion
of South Fork Spring Creek to Rock Creek, and treatment.

(CA-4) Complete capping, groundwater interception, and treatment.

(CA-5) Enlargement of SCDD, diversion of upper Spring Creek to
Flat Creek, and diversion of South Fork Spring Creek to
Rock Creek.

(CA-6) Enlargement of SCDD, diversion of upper Spring Creek to
Flat Creek, diversion of South Fork Spring Creek to Rock
Creek, and copper cementation for flows from Richmond
portal, Lawson portal, and Old No. 8 seep.

(CA-7) Enlargement of SCDD, diversion of upper Spring Creek to
Flat Creek, diversion of South Fork Spring Creek to Rock
Creek, complete capping above Richmond orebody, ground
water interception, and copper removal from Richmond
portal, Lawson portal, and Old No. 8 flows using copper
cementation.

(CA-8) Treatment of AMD from the Richmond portal, Lawson portal,
and Old No. 8 seep with lime/limestone treatment, complete
capping, Upper Spring Creek diversion, South Fork Spring
Creek diversion, Upper Slickrock Creek diversion, and
enlargement of Spring Creek Debris Dam. This alternative
includes disposal of dewatered sludge from the treatment
process in Brick Flat Pit.

(CA-9) Filling all the major mine workings (Hornet, Richmond,

No. 8, and Old Mine orebodies) with LDCC, partial capping,
Upper Spring Creek diversion, South Fork Spring Creek
diversion, Upper Slickrock Creek diversion, treatment of
the remaining AMD from the three major sources by lime/
limestone neutralization, and disposal of dewatered
treatment sludge in Brick Flat Pit, and enlargement of
Spring Creek Debris Dam.

(CA-10) Excavation of the upper portions of the orebody, waste

rock, and tailings piles and off-site disposal in a lined

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- 43 -

facility^- removal of contaminated sediments in the
affected tributaries and the Spring Creek Reservoir#
and the removal of the Minnesota Flats Tailings pile.

(CA-11) Removal of the Minnesota Flats Tailings pile and bottom
sediments in the tributaries and Spring Creek Reservoir
with off-site disposal; collection of the leachate from
all point and non-point sources* and treatment of the
collected leachate with lime neutralization. This
alternative includes construction of a nearby RCRA-type
sludge disposal facility.

(CA-12) Utilization of the Spring Creek Reservoir as a collection
basin for all point and non-point sources and treatment
of all liquids passing through the reservoir with lime
neutralization.

• NO ACTION ALTERNATIVE

The ability to successfully discharge contaminated water
from Spring Creek Reservoir to meet dilution requirements depends
on several factors. The timing of the storms occurring on Spring
Creek watershed, the available storage in Spring Creek Reservoir
when storms occur, and the available dilution water being released
from Shasta Lake are all factors that determine whether or not
contaminated water from Spring Creek will spill. Therefore,
historical data from four different years were used to evaluate
the effectiveness of the proposed alternatives. The year 1978
was selected because above average runoff occurred on the Spring
Creek watershed and there was little dilution water available
from Shasta Lake while water was being stored to replenish lost
water supplies following two years of drought; this year was
identified as the 'worst case' year. The years 1980 and 1981
were selected because total runoff from the Spring Creek watershed
was about average for the period of record from 1967 to 1984.
The 1983 water year was used because that year had the highest
runoff volume into Spring Creek Reservoir for the period of
record. In all cases, the data factored into the water quality
model reflected the U.S. Bureau of Reclamation's (Bureau)
operation plan for Shasta Lake for each of the four case years.
The alternatives were analyzed assuming that the Bureau would
continue to operate according to its plan for Shasta Lake. The
alternatives do not necessarily require a modification of the
Bureau's operating plans.

Alternatives CA-1 through CA-7 were evaluated for four
different water years (described above) and two different sets
of aquatic water quality criteria (also previously desccibed);
CA-8 and CA-9 were analyzed for two water years and two sets of
aquatic water qualit/.

-------
- 44

The point of compliance with the water quality criteria for
alternatives CA-1 through CA-9 is below Keswick Dan (the most
upstream point to which salmon can migrate).

Alternative CA-10 should achieve aquatic water quality
criteria everywhere from the site proper downstream. Alterna-
tive CA-11 should achieve water quality criteria below the
proposed collection daras, constructed on Boulder Creek and
Slickrock Creek, but it would leave the tributaries near Iron
Mountain Mine devoid of aquatic life. Alternative CA-12 should
achieve water quality criteria below Spring Creek Reservoir, but
it would leave the reservoir and points upstream devoid of aquatic
life.

P. Alternative Screening

According of the NCP, alternatives must be developed
for each of the following five categories "to the extent
that it is both possible and appropriate".

a) Alternatives for treatment or disposal at an off-site
RCRA permitted facility approved by EPA.

b) Alternatives that attain applicable and relevant federal
public health or environmental standards.

c) As appropriate, alternatives that exceed applicable and
relevent public health or environmental standards.

d) Alternatives that do not attain applicable or relevant
public health or environmental standards but which will
reduce the likelihood of present or future threat from
the hazardous substances. This must include an alternative
that closely approaches the level of protection provided
by the applicable or relevant standards and meets CERCLA's
objectives of adequately protecting public health and
welfare and the environment.

e) A no-action alternative.

The following is a description of how each of the above combined
remedial action alternatives and the total removal of the source
alternative fits into each of the five categories:

a. Offsite disposal at a RCRA-approved facility

The only alternative that fulfilled these requirements
is CA-10.

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Alternatives fully complying with all applicable or
relevant* standards, guidance, and advisories

CA-10. For all racticable purposes, this is the same
alternative as tne one that exceeds all applicable and
relevant and appropriatate standards. Due to data
limitations, it was not possible to identify what lesser
portion of the orebody and other sources would need to
be removed to exactly meet all standards, guidance, and
advisories. This would require mapping the fractures,
faults, and all pathways of migration through the
mineralized zone and determining the volume, quality,
and location of contaminants discharged to receiving
waters on a seasonal basis. This would involve an
extensive underground exploratory program lasting several
years at an estimated cost of about $5 million, it
should be stressed that at the start of the Remedial
Investigation (RI) in 1983, the RI/PS guidance had not
clearly delineated that alternatives be developed for
each of the five categories; there was, therefore, no
perceived need to conduct an RI of such a comprehensive
scope.

Alternatives exceeding all applicable or relevant
standards, guidance, and advisories.

CA-10.

Alternatives meeting all CERCLA goals, but not fully
complying with all applicable or relevant standards,
guidance and advisories.

Alternatives CA-2 through CA-9 and CA-11 and CA-12.
Combined alternatives CA-5 through CA-9 vary on their
ability to meet appropriate and relevant environmental
standards based on the amount of storage provided by
the enlargement of the Spring Creek Reservoir.

A oo-action alternative.

The No-Action alternative was carried through the
Feasibility Study as a baseline to compare remedial
action alternatives.

The combined alternatives matrix (Table 12) describes
each alternative, presents the capital and operation
costs to meet EPA standards for 1978 and the antici-
pated benefits of each alternative.

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Table 12

Combined Alternatives Matrix5

ALTERNATIVE

No Action

CA-1 Upper Spring Creek and South
fbrk Spring Creek diversions
combined with complete capping
above the Richnond orebody,
groundwater interception, and
copper cementation

Cfc-2 Upper Spring Creek and South
FOrk Spring Creek diversions#
combined with complete capping
above the Ridmond orebody
and groundwater interception
caabined with treatment

POST ($ Million)

Capital OfcM (Present WOrth)

80.3 20.82

AUTICIBAUP BENEFIT

EPA Water Qiality Criteria (EPAHQC)
State Basin Plan Objectives (SBPO)

No benefit! oontimied degradation
of water quality

Achieves EPAWQC below Keswick Dam
for water years 1980 and 1983 jwid
SBPO for Mater year 1980 only.

Does not achieve EPfMQC or SBPO
for Mater years 1978 or 1981.

Achieves EPAHQC and SBPO below
Keswick Dam for all four water
years considered.

Cft-3 Upper Spring Creek and South 69.4

Fbrk Spring Creek diversions
coifcined with treatment

CA-4 Complete capping above the 129.3

Richmond orebody and ground-
water interception combined
with treatment

CA-5 Enlargement of Spring Creek 37.4

Debris Dam >to 23,000 acre-feet,
combined with uppper firing
Greek and South Pork Spring
Creek diversions

CA-6 Enlargement of Spring Creek 30.6

Debris Dam to 23,000 acre-feet,
combined with upper Spring

Creek and South Pork Spring
Creek diversions, and
mnnor rpmentation

20.22 Achieves ERAHQC and SBPO below

Keswick Dam for ail four water
years considered.

22.82 Achieves EPAMQC and SBPO below

Keswick Dm for ail four water
years considered.

0.6^ Achieves EPAWQC and SBPO below

Keswick Dm for all four water
years considered.

l.|2 Achieves EBRMQC and SBPO below

Keswick Dot for ail four water
years considered.

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ALTERNATIVE

CAr-7 Enlargement of Spring Creek

Debris Dan to 18,000 acre-feet,
combined with upper Spring
* Oreek and South Fbrk Spring
Creek diversions, copper
cementation, complete capping
above the Richmond orebody,
and groundwater interception

CIH! Treatment of Richmond portal,
Lawson portal, and Old Nb. 8
with lime/limestone; total
capping; upper Slickrock
Creek diversion; upper Spring
Greek diversion; South fork
Spring Creek diversion; and
enlargement of Spring Creek
Debris Dm (if needed)

CAr-9 Injection of low-density

cellular concrete into old
mine workings (Hornet, Richmond,
Old Nine, and Old No. 8);
partial capping; upper Spring
Creek diversion; upper Slickrock
Creek diversion; South fbrk
Spring Creek diversion; and
enlargement of Spring Creek
Debris Dam (if needed)

CA-10 Excavation of the upper portions
of the orebody, waste rock, and
tailings piles with off-site
disposal in a lined facility;
removal of contaminated sediments
in the affected tributaries and
the Spring Creek Reservoir; and
the removal o£ the Minnesota
Flats tailings pile.

liable 12 (Continued)

006T ($ Million)

Capital QtM (Present Worth)
40.9 1.92

ANTICIPATED BENEFIT

EPA Mater Quality Criteria (EPAWQC)
State Basin Plan Objectives (SBPO)

Achieves EPAWQC and SBPO below
Keswick Dm for all four water
years considered.

42.3 13.02 Achieves EPAMQC and SBPO below

Keswick Dam for all four water
years considered.

68.1 4.12 Achieves EPAHQC and SBPO below

Keswick Dan for all four water
years considered.

1,400 0.03 Achieves background water <*iality

at all points.

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Table 12 (Continued)

ALTERNATIVE

COST ($ Million)

CA-11 Removal of the Minnesota Plats
tailings pile and sediments in
the tributaries and Spring
~ Creek Reservoir with off-site
disposal; collection of leachate
from all point and non-point
sources, and treatment of the
collected leachate with lime
neutralization. This alterna-
tive includes construction of
a nearby RCRA-type sludge
disposal facility.

CA-12 Utilization of the Spring Creek
Reservoir as a collection basin
for all point and non-point
leachate sources and treatment
of all liquids passing through
the reservoir with lime
neutralization.

Capital OfcM (Present Worth)
351«

ANTICIPATED BENEFIT

263*

EPA Water Quality Criteria (EPAHQC)
State Basin Plan Objectives (SBPO)

Achieves background water quality
at all points below the leachate
collection impouncftnents near the
confluence of Spring Creek and
Plat Creek and Spring Creek and
Slickrock Creek. Plat Creek
and Slickrock Creek will remain
contaminated upstream of thpse
impoundments. 4

Achieves background water quality
at all points below Spring Creek
Reservoir. The reservoir and
upstream tributaries will renin
contaminated.

Notes:

1. Since CA-1 did not meet water quality objectives, costs were not computed further, and CA->1 was effectively
screened out.

2. Costs canputed for achieving EPAHQC below Keswick Dam for water year 1978.

3. Costs for CA-10 through CA-12 not computed to same level of detail as for CA-2 through CAr9.

4. These costs include both capital and 0&M costs.

5. Technical, environmental, public health and institutional considerations can be found in Table 11 for the
components which make up the conbined alternatives.

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- 49 -

VII. THE IRON MOUNTAIN MINE REMEDY

Among the remedial action alternatives that could be imple-
mented by EPA, the total removal of the source and sediments in
receiving waters (Alternative CA-10) is considered the only remedy
for the Iron Mountain Mine site which is capable of meeting pro-
ject cleanup objectives and the full requirements of the Clean
Water Act (CWA). This alternative would effectively eliminate
discharges from Iron Mountain and restore all tributaries to
pristine condition. This alternative was..based on total removal
of all the sources of contamination and hauling and disposing of
them in a RCRA-approved facility. This includes material from
the following four areas:

a) Remove approximately 3.5 million cubic yards of ore and
waste rock and tailings piles along Boulder Creek and Slickrock
Creek.

b) Remove an estimated 200,000 cubic yards of contaminated
bottom sediments in Slickrock Creek, Boulder Creek and Spring
Creek. It was assumed that sediment in Slickrock Creek near the
Brick Flat Pit area would be removed using conventional construction
equipment. For sediment removal in the other receiving waters,
hydraulic clearing was assumed.

c) Remove approximately 620,000 cubic yards of contaminated
bottom sediments in Spring Creek Reservoir.

d) Remove about 14,000 cubic yards of tailings material in the
Minnesota Flat area.

The total cost of excavating and removing the source material
and hauling it to a Class 1 landfill was estimated to be $1.4
billion.

Alternative CA-11 comes next closest to meeting all require-
ments, but water quality standards will not be met in Boulder
Creek and Slickrock Creek and not all non-point sources will
be addressed through Best Management Practices (BMP's). This
alternative is the same as the total removal alternative except
it does not include removing the orebody. It only includes
removing bottom sediments in the creeks and reservoir and the
Minnesota Flat Tailings pile. All costs developed for this
portion of this alternative are based on the same assumptions
discussed in CA-10. This would consist of excavating and removing
over 800,000 cubic yards of waste to a RCRA approved landfill
which is estimated to cost about $200 million.

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50

This alternative will collect all point and non-point
sources in Slickrock Creek and Boulder Creek? the contaminated
water would be conveyed to a lime neutralization facility for
treatment. This alternative would also include constructing
a nearby sludge disposal site which would meet RCRA guidelines
and all other institutional requirements. The estimated cost
of treatment is $151 million, bringing the total cost of the
alternative to $351 million.

Alternative CA-12 will meet background water quality in the
Sacramento River below Keswick Dam but the applicable federal and
state standards will not be met in Boulder Creek, Slickrock
Creek, portions of Spring Creek, and in the Spring Creek Reservoir.
This alternative involves allowing all point and non-point sources
of pollution to discharge to Boulder Creek and Slickrock Creek,
and then flow into the Spring Creek Reservoir. Contaminated
water would then be pumped to a lime neutralization facility for
treatment; treated water would be discharged to the Sacramento
River. The resulting lime sludge would be disposed of in a nearby
disposal site which would meet RCRA guidelines and other
institutional requirements. Water quality standards should be
met in Flat Creek since the only source of pollution, Minnesota
Flats Tailings pile will be removed under this alternative. Also,
non-point sources will not be treated with BMP's.

Under CA-1, water quality standards would not be met in
either the immediate receiving waters or in the Sacramento River
below Keswick Dam for several of the case years evaluated. CA-2
through CA-9 would improve water quality to varying degrees in
immediate receiving waters, although not to the point where
state water quality standards will be met; these objectives
will, however, be met in the Sacramento River below Keswick Dam.
With the exception of CA-9, these alternatives will not address
discharges from non-point sources.

VIII. FUND BALANCING

Under 40 CFR 5300.68(i)(1), the appropriate extent of remedy
must be the cost-effective remedial alternative that effectively
mitigates and minimizes threats to and provides adequate protection
of public health and welfare and the environment. In addition,
the remedy must be that which attains or exceeds applicable or
relevant and apropriate Federal public health and environmental
requirements that have been identified for the site. However,
under S300.68{i)(5)(ii), EPA may select an alternative that does
not meet applicable or relevant and appropriate Federal public
health or environmental requirements when the need for protection
of public health and welfare and the environment at the facility
for all of the alternatives that attain or exceed applicable or
relevant and appropriate Federal requirements is outweighted by
the need for action at other sites that may present a threat to
public health or welfare or the environment, considering the

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amount of money-available in the Hazardous Substance Response
Trust Fund. In the event of Fund-balancing, EPA oust select the
alternative which most closely approaches the level of protection
provided by applicable or relevant and appropriate Federal
requirements, considering the specific Fund-balanced sum of money
available for the facility.

The estimated cost to implement the remedy (CA-10) that would
meet applicable or relevant and appropriate Federal environmental
and public health standards for the Iron Mountain Mine site is
estimated to be $1.4 billion. EPA evaluated the funds remaining
under the current Superfund authorization and subsequent interim
fundings. In our analysis, we have considered that increased
funding may become available if the pending Superfund reauthoriza-
tion is enacted.

At this time, funds under the current Superfund authori-
zation and the subsequent Interim funding are nearly depleted;
funding that remains is committed solely to keep ongoing remedial
planning activities on an active status. Therefore, these remain-
ing funds are not only unavailable to Iron Mountain Mine but,
even if available, would not be adequate to implement an operable
unit or final remedy at the site.

The Superfund reauthorization, if enacted, may provide
funding in an amount ranging from $5.4 billion to about $8.5'
billion in order to respond to 888 proposed and final NPL sites
over a five year period ($1.7 billion annually). Committing
$1.4 billion, or 16 to 26 percent of the potentially reauthorized
amount, to the cleanup of Iron Mountain Mine would effectively
consume at least the equivalent of one year's worth of funding.
This would be at the expense of remedial response action at NPL
sites, expenditures for emergency response action, and other
program needs. This would severely limit the capability of the
Agency to take timely and effective cleanup action where needed
to protect public health and welfare and the environment. The
full impact of commiting these funds solely to Iron Mountain
Mine would be to deny funding for site cleanup at between 140
and 470 NPL-sites (assuming that the typical cost of Remedial
Design and Remedial Action for an NPL site ranges from $3
million - $10 million).

As previously mentioned, Alternative CA-11 at a cost of
$351 million is the alternative that most closely approaches but
does not achieve the requirements of the CWA. This alternative
would utilize Boulder Creek and Slickrock Creek to capture all
point and non-point sources of pollution; contaminated water
would then be pumped from each of the two creeks to a lime
neutralization facility for treatment. Alternative CA-11
is expected to further degrade water quality beyond current
conditions in these receiving waters. The reason is that, at
present, discharges of AMD from the three major sources of

-------
pollution are receiving copper cementation treatment prior to
discharge to receiving waters. Nevertheless, water quality in
Spring Creek, Spring Creek Reservoir, and Keswick Reservoir would
improve substantially to the point where certain beneficial uses
may return on a year round and/or seasonal basis. Water quality
below Keswick Dam would improve beyond that required to
protect fish in the Sacramento River. Committing funds for this
alternative would be at the expense of funding cleanup actions at
between 35 and 117 NPL sites.

Alternative CA-12 would further degrade water quality in
Boulder Creek, Slickrock Creek, portions of Spring Creek and in
Spring Creek Reservoir because AMD from the three major sources
of pollution will not receive copper cementation treatment prior
to discharge to receiving waters. Contaminated water would be
pumped from Spring Creek Reservoir to a lime neutralization
facility for treatment and then discharged to the Sacramento
River. However, water quality in Keswick Reservoir and below
Keswick Dam would improve substantially; water quality below
Keswick Dam would be essentially the same as that in the Sacramento
River above the confluence where discharges from Iron Mountain
Mine enter the river. The level of cleanup provided by this
alternative is higher than that needed to protect aquatic life
in the Sacramento River below Keswick Dam* Funding this alter-
native would preclude EPA from taking cleanup action at between
26 and 87 sites on the NPL.

After considering these fund-balancing issues, CA-9 ($72.2
million) is the alternative that most closely approaches the
requirements of all applicable or relevant and appropriate federal
and state requirements, yet it also balances the need to conserve
monies in the Fund. Funding this remedy would have a less sign-
ificant impact on EPA's ability to use the fund at other sites,
yet it would also provide significant protection at the IMM site.
Alternative CA-9 will meet Federal Water Quality Standards for
aquatic life below Keswick Dam for all water years considered;
the State Basin Plan standards should be met for other than the
'worst case' condition. Meeting these criteria and standards
should protect the salmon population in the Sacramento River
below Keswick Dam. In addition, implementation of Alternative
CA-9 should greatly improve water quality in the tributary streams
between Iron Mountain and the Sacramento River. The basis for
identifying CA-9 as the Fund-balanced remedy is discussed in
more detail in Chapter IX.

IX. SUMMARY EVALUATION OF ALTERNATIVES

With the exception of CA-1, each combined alternative
will meet the two project cleanup objectives for each of the
case years for which they were analyzed. Alternative CA-1
will not meet EPA standards for 1978 and 1981 conditions or
State Basin Plan objectives for the years 1978, 1981, and 1983.

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53

A. Feature* and Costs of Combined Remedial Alternatives

Alternative CA-1 does not meet either CPA or State water
quality objectives and is not considered an appropriate
remedial action alternative for site cleanup because releases
from the site would continue to present acute and chronic
impacts on aquatic life.

Alternatives CA-2, CA-3, and CA-4 will meet both EPA and
State water quality objectives through various combinations of
source control, lime/limestone neutralization treatment, and
water management alternatives at costs ranging from $89.6 million
to $151.1 million. These alternatives differ in the number of
AMD sources that will receive treatment.

Alternatives CA-5, CA-6 and CA-7 will also meet both
project cleanup objectives at a cost substantially below
those projected for Alternatives CA-2 through CA-4. These
alternatives differ most notably in the Increased storage
capacity of the Spring Creek Reservoir provided by the enlarge-
ment of Spring Creek Debris Dam. Alternative CA-5 will meet
cleanup objectives by relying exclusively on water management
measures to ensure that adequate dilution water is available
to meet project cleanup objectives below Keswick Dam. Under
this alternative, no source control or treatment remedies
would be implemented. Alternative CA-6 is similar to Alterna-
tive CA-5 except that this alternative would utilize copper
cementation treatment of 'controlled* AMD flows at a lower
cost to meet CPA cleanup objectives and slightly higher cost
to meet State cleanup objectives. Alternative CA-7 relies
upon source control, treatment, and water management remedies
to meet CPA and State cleanup objectives at a higher cost
than both Alternatives CA-5 and CA-6 but considerably lower
than Alternatives CA-2 through CA-4.

Alternatives CA-8 and CA-9 meet project cleanup objectives
through a variety of source control, treatment, and water
management remedies. These alternatives are very similar
and differ only in the extent of capping that would be
required over the Richmond orebody, and the volume of AMD
receiving lime/limestone neutralization treatment. CA-9
also includes the injection of low-density cellular concrete;
this is not a component remedy of CA-8. CA-8 will meet
federal and state objectives at costs ranging from $55.3
million - $62.7 million; CA-9 will meet the same objectives
at a cost of $72.1 million to $85.1 million. Although the
cost of CA-9 may be higher, the actual cost of CA-9 may be
less for several reasons: a) further studies may indicate
that the underground mine workings do not need to be completely
filled with LDCC; 2) if waste rock at Big Seep can be used in
the formation of LDCC, the Upper Slickrock Creek diversion
($790,000) could possibly be eliminated; and 3) if LDCC is

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fully successful, it would preclude the need to construct a
lime neutralization facility, which has an estimated capital
cost of about $8 million. More important, however, CA-9
is an approach that aggresively moves to stop AMD formation.

Under other alternatives, for instance, AMD may continue to
be formed, and thus require treatment, for hundreds of years.

B. Evaluation of Combined Remedial Alternatives

CA-2 through CA-4 will meet primary &nd secondary cleanup
objectives and the goals of the NCP at a relatively high cost
when compared to the other alternatives. CA-2 and CA-3 treat
the five major sources of pollution plus all other sources
discharging in Slickrock Creek through lime neutralization;
CA-4 addresses these same sources in addition to treating all
other sources in Boulder Creek. These alternatives will be
generating tremendous volumes of lime sludge each year which, on
a periodic basis will continue to require the identification and
development of new off-site disposal areas. Treatment of AMD
and off-site disposal will be required for a period of time
far exceeding the 30-year project period, and perhaps be needed
in perpetuity. This, in effect, significantly increases the
State's commitment to operate and maintain the lime neutralization
facilities, and will require that nearby undeveloped land be
committed for land disposal for as long as Iron Mountain Mine
continues to discharge AMD. The need for long-term treatment
tends to make these alternatives less reliable. These alter-
natives would reduce the metals loading to receiving waters and
meet Federal and State standards, but for the added cost, would
not result in a further improvement in Water Quality at the
point of compliance. For the above reasons, CA-2 through CA-4
are not considered cost-effective remedies for the Iron Mountain
Mine problem.

CA-5 will meet both EPA and State water quality objectives
at the point of compliance (primary objective) at a relatively
low cost, but will not meet a principal goal of the NCP or
the secondary cleanup objective. The reason for this is
that CA-5 does not address the problem at its source or
minimize the migration of hazardous substances, pollutants or
contaminants because it relies exclusively upon the dilution
of these pollutants to meet primary cleanup objectives. For
these reasons, this alternative was not considered to be an
appropriate remedy for Iron Mountain Mine.

CA-6 utilizes copper cementation treatment, and like
CA-5, relies on dilution to meet primary cleanup objectives.
For the same reasons as discussed under CA-5, and in considera-
tion of the fact that copper cementation will not meet the
BAT requirements of the CWA, this alternative was not considered
an appropriate CERCLA response to the Iron Mountain Mine problem.

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55

When compared to CA-5 and CA-6, alternative CA-7 provides an
improved balance of source control* treatment and water management
components to meet primary and secondary cleanup objectives at
a slightly higher cost. CA-7 also utilizes copper cementation
treatment and, thus, will not meet Best Available Technology#
as specified by the CWA. CA-7 will result in a reduction of
pounds per day of heavy metals entering the Sacramento River
through implementation of source control and treatment alterna-
tives, but to a lesser extent when compared to other source
control and lime neutralization treatment alternatives. This is
because the copper cementation process does not remove cadmium or
zinc from the AND. Therefore, while CA-7 will meet the primary
cleanup objective, it will only partially fulfill the secondary
objective. Also, CA-7 will do very little to improve overall
water quality in immediate receiving waters. For these reasons,
CA-7 was not considered an appropriate remedy for Iron Mountain
Nine.

CA-8 and CA-9 are very similar as previously noted and will,
therefore, be evaluated together. Both of these alternatives
provide a good balance of source control, treatment and water
management. By utilizing lime neutralization treatment of the
three major sources, both CA-8 and CA-9 will satisfy the BAT
requirement of the CWA. This, combined with capping (and in the
case of CA-9 the use of LDCC) will result in substantial water
quality improvement in the immediate receiving waters and will,
therefore, reduce the amount of heavy metals discharged to the
Sacramento River. For approximately 6-8 months of the year, from
about late-Spring to early-Fall, there should be no discharges of
AND to receiving waters. During these periods, it is anticipated
that there will be a return of certain beneficial uses to Keswick
Reservoir and possibly a return of other beneficial uses to
portions of Spring Creek.

In the case of CA-9, lime neutralization treatment may not
be needed if the injection of LDCC is successful in preventing or
reducing the formation of AND. Even if LDCC is not fully success-
ful, the volume of AND that would need to be treated is thought
to be much less than under CA-8. Therefore, Brick Flat Pit will
have a sustained storage life for lime sludge beyond the 30-year
period calculated for CA-8. This means that off-site disposal
can be postponed to a later date and the rate of developing new
off-site disposal sites under CA-9 will be slower when compared
to CA-8. CA-9 will also utilize waste rock and tailings piles
and treated AND from the three major sources when formulating the
LDCC. This brings CA-9 an additional step forward in meeting
the requirement of the CWA by addressing non-point sources;
these sources will not be addressed by CA-1 through CA-8.

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- 56

The most attactive feature of CA-9, however# is the use of
LDCC. If fully successful, this alternative could prevent or
significantly reduce AMD to a point where treatment may not be
required. This, of course, would mean that there would no longer
be a need to utilize Brick Plat Pit as a storage basin or a need
to identify and develop new off-site lime sludqe disposal sites.
It is this aspect of CA-9 that makes it a superior choice over
the other combined remedial action alternatives.

X. IDENTIFICATION OF FUND-BALANCED REMEDY AND REMEDY SELECTION
STRATEGY

Alternative CA-9 is the appropriate Fund-balanced remedy
for Iron Mountain Mine. Alternative CA-8 is EPA's next preferred
alternative. These two alternatives differ principally in the
use of LDCC, in the volume of AMD to receive lime/limestone
neutralization treatment, and whether a partial cap (CA-9) or
complete cap (CA-8) is constructed.*

Full implementation of alternative CA-9 is expected to
significantly improve water quality in the Iron Mountain Mine
area. Table 13 presents the anticipated water quality benefits
that should result from CA-9. Water quality in Keswick Reservior
and the Sacramento River would also see similar water quality
improvements. Removing the Minnesota Flats Tailings pile, the only
known source to impact Flat Creek, would result in immediate
improvements in water quality and, over time, may cause a return
of all beneficial uses to this water course.

Reducinq the metals loading to receiving waters would also
mean that there are fewer heavy metals in solution; fish in the
Sacramento River have been shown to bioaccumulate these metals.
If it were possible that bioaccumulation, which has been demon-
strated in fish tissue, was also causing a potential human health
problem, we anticipate that this impact would be eliminated or
reduced by the remedial action program.

Also, installation of perimeter control (i.e., fencing,
posting warning signs) should minimize potential public health
impacts associated with coming into contact with AMD or AMD-laden
waters.

The selected alternative for this operable unit consists
of the source control and water management components that are
common to both CA-3 and CA-9. The Agency is not now prepared
to make a final decision on whether to proceed with the source
control measure of injecting low-density cellular concrete into
the underground mine workings or straight lime/limestone neutrali-
zation treatment of AMD. To assist in making this decision,

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Table 13. Anticipated Water Quality Improvements with CA-9
Current Water Quality (mq/1) CA-9

RECEIVING WATER

OOPPER

ZINC

CADMIUM

BOULDER CREEK

4.25

25.0

0.17

2.1-
3.3

SUCKROCK CREEK

2.56

0.99

0.012

3.5-
4.1

SPRING CREEK

1.2

4.7

0.03

3.0-
3.4

COPPER

ZINC

CADMIUM

1.20

6.1

0.03

2.7-
4.0

0.15

0.06

0.001

4.7-

5.5

0.47

2.1

0.01

3.4-
4.5

Ul
I

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- 58 -

this ROD authorises EPA to conduct a hydrogeologic investigation,
and LDCC pilot and demonstration testing to determine a) if the
site is conducive to the application of LDCC; b) the proper
formulation of LDCC needed to withstand AMD corrosion; and c) if
LDCC is technically feasible# reliable, and can be successfully
implemented at Iron Mountain Mine. If these studies conclude
that LDCC is technically feasible and can be implemented, EPA
will prepare a second Record of Decision (ROD) documenting the
selection of the source control measure.

Alternatively, if the site is not conducive to the applica-
tion of LDCC or if LDCC is judged to be technically infeasible,
a second ROD will be prepared to select the components of CA-8
(complete capping of the Richmond orebody and lime/limestone
treatment) that have not been selected by this ROD.

* Construction of a partial or complete cap over the
Richmond ore body is consistent with EPA's current
view of Iron Mountain as a waste source. A cap will
reduce infiltration of precipitation and thus reduce
the volume of acid mine drainage that is formed.

However, the ore body could be considered a resource,
suitable for exploitation by a solution mining process
(as currently proposed by the potentially responsible
parties). Placing a full or partial cap over the ore
body could be a hindrance to efforts to implement a
solution mining process. Therefore, EPA will not begin
implementation of the capping component for a grace
period, while the possibility of developing the ore
body as a resource is considered further. Commercial
development of the ore body would have to.include acid
mine drainage discharge control measures and other
environmental safeguards. A final decision regarding
the capping component will be made following che
grace period.

XI. SUMMARY OF RECOMMENDED OPERABLE UNIT

The recommended operable unit consists of:

o Approximately 2.5 acres of cracked and caved ground
areas above the Richmond orebody will be capped using a
soil cement mixture or other suitable material. The
areas will be graded and benched and covered with the soil
cement mixture. Interception ditches will be used to
divert clean surface water runoff from the orebody.

o Up to 800 cubic feet per second (cfs) of clean .surface
water will be diverted from the Upper Spring Creek
watershed before it reaches that portion of the basin
affected by Iron Mountain Mine. This will be accomplished
by constructing a low diversion dam and an 8-foot tunnel .

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59

through theridge that separates the Spring Creek and
Flat Creek watersheds. A chute and energy dissipators
will be needed to complete the conveyance of flows from
Spring Creek to Flat Creek.

o Up to 250 cfs of clean water will be diverted from
the South Fork of Spring Creek across the drainage
divide into Rock Creek which discharges to the Sacramento
River below Keswick Dam. The purpose of this alternative
is similar to the Upper Spring Creek diversion and will
require a small diversion dam and 4,000 feet of pipeline
to complete the conveyance of flows to Rock Creek.

o Clean water from Upper Slickrock Creek will be diverted
around the waste rock and slide debris, which contribute to
releases from Big Seep, to the lower reach of Slickrock
Creek.

o Spring Creek Debris Dam will be enlarged from its present
storage capacity of 5,800 acre feet to 9,000 acre feet.

o Installation of Perimeter controls as necessary to minimize
any direct contact threats.

o Perform hydrogeologic study and field-scale pilot
demonstration to better define the feasibility of utilizing
LDCC to minimize AMD formation.

XII. RECOMMENDED CLEANUP OBJECTIVES AND DESIGN YEAR

Designing a cleanup program to meet EPA Water Quality
Criteria for Protection of Aquatic Life for the 'worst case'
condition (1978) was judged to be appropriate because it is under
conditions similar to 1978 that the greatest impacts on aquatic
life would be felt. It should be noted that the so-called
"worst case" ys*r is based on very few years of data. Also,
water quality model rjns predicted that, targeting a cleanup
program to meet EPA w*ter quality criteria for the 1978 runoff
conditions (wet year following a drought) would ensure that more
stringent State criteria for the other three cleanup case years
would be met. Stated differently, the EP* program should meet
State criteria for every year except the worst case year, at
which time the federal standards will be met. Under these
conditions, meeting federal standards should prevent fish kills
from occurring in t"i«i Sacramento River.

XIII. CONSISTENCY WITS OTHER ENVIRONMENTAL LAWS

According to the NCP, 40 CFR Part 300.68 (i)(l), remedial
actions must attain or exceed applicable or relevant and appro-
priate Federal public health and environmental requirements

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- 60

unless one of the exceptions of Section 300.69(i)(5) applies.

One of these exceptions is Fund-balancing. This provision allows
EPA to select the alternative which most closely approaches
the level of protection provided by applicable or relevant and
appropriate requirements by considering the amount of money
remaining in the Trust Fund and the need to take action at other
NPL sites.

The selected overall remedy (CA-9) is presented for the
discussion of the consistency with other environmental laws even
though the current ROD is for the first operable unit only. The
selected remedy would fill the major mine workings with low-density
cellular concrete to greatly reduce AMD production? partially cap
Iron Mountain to reduce the infiltration of clean water into the
ore body; divert clean surface waters away from tailings piles
and contaminated areas; if necessary, treat the (reduced) flow
of AMD from the major point sources by lime neutralization; and
enlarge Spring Creek Debris Dam to provide flow equalization.
In order to reduce infiltration of clean water into the mountain,
some grading and filling of depressions is anticipated in addition
to the partial cap. In particular, an open pit called the Brick
Flat Pit is to be filled to prevent accumulation of water.

Dewatered sludges from the lime neutralization process, as well
as the tailings from the Minnesota Flats Tailings piles, will be
placed in the Brick Flat Pit. The selected remedy does not:
address all waste rock dumps or tailings piles along Boulder
Creek and Slickrock Creek; collect and treat all seeps or sub-
surface drainage along Boulder Creek and Slickrock Creek; address
metal-bearing sediments in receiving waters; or fully achieve
aquatic water quality standards in Boulder Creek, Slickrock Creek,
portions of Spring Creek, and Keswick Reservior. In essence,
the selected remedy will achieve aquatic water quality standards
below Keswick Dan, but not in the tributary streams; however,
water quality in these receiving waters is expected to improve
substantially to the point where certain beneficial uses may
return on a seasonal basis.

The major environmental statutes that should be addressed
with regard to this site include the Resource Conservation and
Recovery Act (RCRA), the Clean Water Act (CWA), the National
Environmental Protection Act (NEPA), and the Endangered Species
Act (ESA). In addition, the selected alternative's consistency
with a number of other Federal and State regulations is discussed
in the Feasibility Study and its Addendum.

RCRA

The partial capping of the mountain and the filling of

Brick Plat Pit with tailings from the Minnesota Flats area as

well as disposing of dewatered lime sludges are two components

of the selected remedial action that are of interest here. Iron

Mountain Mine is an inactive mining site, and the solid materials

•

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- 61 -

found at the sit*. are considered mining wastes; hence, RCRA is
nnt generally applicable or relevant or appropriate. However,
portions of the RCRA Subtitle C requirement nay be relevant and
appropriate for some aspects of the remedy, we considered the
RCFA Subtitle C requirements in formulating various aspects of
the alternative remedial actions. Xn addition. Subtitle D require-
ments may be appropriate at the site. In particular, qrading
and capping to reduce infiltration of rain waters into tailings
piles (or the ore body) seems appropriate. The partial cap is
intended to be placed over badly fractured areas and areas of
relatively low slope. A soil/cement mixture appears to be the
most cost-effective approach to reducing infiltration into the
- ore body: The multi-layered clay cap does not appear to be
necessary for this application. Also, because of the steepness
of some of the slopes, complete capping of the mountain is not
technically feasible or practical.

With regard to the disposal of sludges generated by the lime
neutralization process, it may be most protective to place the
sludges (after dewatering) in a double-lined facility. Such a
facility would have to be located off-site, because there are no
areas suitable for such a facility on-site. However, the selected
remedy is to place these sludges in Brick Flat Pit on top of Iron
Mountain. This is considered a more appropriate approach for
several reasons: (1) the pit needs to be filled in order to
prevent water from ponding in it, (2) the metals contained in
the dewatered sludge are relatively immobile and hence should be
safe to place in an unlined pit, (3) should the metals migrate,
they would reenter the ore body and eventually be recaptured by
the AMD treatment system, and (4) the pit provides the probable
least-cost disposal option. It is estimated that Brick Flat Pit
could provide 30-plus years of disposal capacity, depending on
sludge generation rates. (If the LDCC is fully successful in
stopping AMD formation, then no treatment would be required, and
no sludges would be generated.)

Placement of the tailings from the Minnesota Flats area
in Brick Flat Pit is also selected. The tailings came from an
ore roasting operation near Iron Mountain, and they contribute
approximately one percent of the total metals discharge from the
site via surface water runoff. Removal of the tailings from
their present location would allow Flat Creek to be restored.
Placement of these materials in Brick Flat Pit is somewhat
analogous to placing materials that have migrated off-site from
a landfill back on the landfill prior to capping. The metals
concentrations are less that those of the underlying ore body,
and the volume is significantly less than that of the ore body.

CWA

Section 301 of the Federal Clean Water *ct requires that
any point source discharge to waters of the United States

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meet technology-based effluent limitations (Best Practicable
Technology Currently Available (BPT) by July 1, 1977, and
Best Available Technology Economically Achievable (BAT) by
July 1, 1984) as well as effluent limitations necessary for
achieving compliance with water quality standards, by July 1,
1977. All Clean Water Act requirements may be met by preventing
discharge. Waters of the United States in the Iron Mountain Mine
area include Boulder Creek, Flat Creek, Slickrock Creek, Sprinq
Creek, Keswick Reservoir, and the Sacramento River.

EPA has determined by Best Professional Judgement that
the effluent limitations for nine drainage at 40 CFR Part 400,
Subpart J, which are achievable by using lime treatment and
precipitation, meet the BPT/BAT/BCT requirements of the CWA for
point source discharges at this site.

Water quality standards established pursuant to the CWA are
currently applicable to the Sacramento River and tributaries
above Hamilton City. These standards were adopted by the Central
Valley Regional Water Quality Control Board on April 27, 1984,
and were approved by the State Water Resources Control Board and
EPA. These standards limit dissolved concentrations of cadmium
(0.00022 mg/1), copper (0.0056 mg/1), and zinc (0.016 mg/1).

Other applicable water quality standards include a pH range of
6.5 to 8.3, with a maximum deviation of 0.3 units from ambient
conditions, as well as freedom from color, turbidity, settleable
material, sediment, toxicity, and suspended materials in amounts
that adversely affect beneficial uses. Water quality standards
are currently violated at all times for each of these water bodies
except for the Sacramento River below Keswick Oam.

While substantial water quality improvement above current
conditions is expected through implementation of Alternative
CA-9, State and Federal standards will probably not be met in
portions of Spring Creek, Slickrock Creek, Boulder Creek, and
Keswick Reservoir at any time. Alternative CA-9 achieves water
quality at a point below Keswick Dam. As described under Fund
Balancing, the cost of meeting water quality objectives in the
stream near the source is extremely large and fund balancing is
used to back off to a less costly remedy.

NEPA

Under NEPA, an Environmental Impact Statement (EIS) must be
prepared for Federally-funded projects. The environmental
analysis included in the Feasibility Study is normally considered
to be the functional equivalent of the EIS. However, in this
case, the environmental impact of the proposed stream diversions
are beyond the scope of the Feasibility Study. Therefore, prior
to final design and construction of water diversion components

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or changes in the crest or pool elevations of the Spring Creek
Debris Dam, the Bureau of Reclamation, under an aqreement with
EPA, will conduct any necessary supplemental environmental
assessments.

ENDANGERED SPECIES ACT OF 1973

The winter run of salmon are being considered by the National
Marine Fisheries Service for protection under the Endangered
Species Act. Therefore# if the Service takes final action to
protect the winter run of salmon, this legislation would be
applicable to the cleanup of Iron Mountain Mine since the site
is the main source of pollution that places the salmon at risk.
The operable unit and final remedy for Iron Mountain Mine will
achieve water quality standards in the Sacramento River below
Keswick Dam, the major spawning area for the salmon. In taking
remedial action at Iron Mountain Mine, EPA will be in compliance
with the intent of the Endangered Species Act.

XIV. OPERATION AND MAINTENANCE

A. Capping of Cracked and Caved Ground Areas

Maintenance will be required for the ditches, benches, and
soil-cement cap. The ditches will require periodic maintenance
consisting of the removal of debris and repair of cracked
sections. Benches will need periodic removal of debris.

B. Water Management Alternatives

•

Expected operation and maintenance requirements are minimal
for these alternatives. There are no mechanical or electrical
system components to maintain and no process to monitor or manage.
It is possible after an extreme runoff event that some repair of
channel erosion damage could be required. Sediment accumulation
could be a problem at some point in the system, although proper
design considerations should reduce any associated maintenance
problems to-a minimum.

XV. COMMUNITY RELATIONS

Documents made available for public review and comment
included the Remedial Investigation (RI) and Feasibility
Study (FS) reports and the Addendum to the FS.

The RI was made available for review and comment in
February 1985, and again on August 2 through August 23«. 1935.
The public comment period for the FS was held between August 2
and August 23, 1985. Public notification of the public

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comment period w*s announced two weeks prior to the public
comment period through notices in local newspapers. A Fact
Sheet summarizing the contents of the RI and FS reports was
sent to the mailing list during the week of July 22, 1985.

A public meeting was held on August 15, 19B5 in Redding, CA.
The ipijority of comments received at the public meeting
were from IMMI and Stauffer. These parties stated their
objections to the implementation of the EPA cleanup program,
and voiced strong support for allowing IMMI to proceed with
its concept for an in situ leaching and metals recovery
project.

Written comments were received from the PRP's, state agencies,
one resident along Flat Creek, and sportsfishing and recreational
organizations. In general, the PRP's and their consultants
supported the IMMI proposal, stated opposition to an EPA funded
cleanup action, and called into Question the credibility of the
FS. State agencies and other organizations lent support for an
EPA funded remedial action and raised concerns about proceeding
with the IMMI proposal. Responses to the comments are presented
in the attached Responsiveness Summary.

A fact sheet summarizing the results of the Addendum to the
FS was sent to the mailing list on July 14, 1986. The public
comment period for the Addendum was held from July 25 through
August 15, 1986. Public notification of the public comment
period was announced about three weeks prior to the public comment
period through notices in local newspapers.

Written comments were received by the PRP's, federal and
State regulatory agencies, two landowners near the site, consultants
associated with IMMI, and 33 citizens who signed petitions and/or
form letters supporting the IMMI proposal, and 5 letters from
residents in the Redding area.

As a general statement, comments from the PRP's and consult-
ants for IMMI stated firm support for the IMMI proposal and
opposition to the EPA proposed cleanup program. There was a
concern that injecting the LDCC into the underground mine workings
would interfere with the IMMI proposal and would also destroy a
valuable mineral resource. The PRP's voiced strong opposition
to proceeding with LDCC because it is an unproven technology for
the purposes for which it would be applied at Iron Mountain
Mine. The PRP's stated that the technology was not technically
feasible; Stauffer indicated that, for this reason, the approach
was not consistent with the NCP because it was not an established
technology. The PRP's also stated that the IMMI proposal was a
far superior alternative and that IMMI had secured funding to
finance its commercial mining venture and an environmental
control program. Stauffer asserted its view that Region IX had
incorrectly interpreted the Clean Water Act in applying BAT for
control of AMD from "abandoned mines"; that water quality
compliance criteria must be negotiated on a case-by-case basis.,

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65

and that the poixit of compliance for meeting cleanup objectives
should continue to be met below Keswick Dam. Stauffer also
protested that the three week public review and comment period
was inadequate and inconsistent with CERCLA and the community
relations provisions of the NCP because the Addendum represented
a sharp departure from the original PS and that important and
complex technical issues were raised by the FS Addendum.

The petition and form letters stated that the IMMI proposal
was needed to bolster Shasta County's economy, that the IMMI
cleanup program was more efficient and cost effective than the
EPA cleanup programs, that the impacts of discharges of AMD on
the Sacramento River are highly questionable, and that the EPA
cleanup program was "basically ludicrous".

Federal and state regulatory agencies agreed with the
implementation of CA-9 as the best solution to the Iron Mountain
Mine problem, although support was also mentioned for CA-8; there
was a consensus of the requlatory agencies opDOsing the IMMI
commercial mining venture as an acceptale response to site
problems. Specific comments and EPA's responses are presented in
the attached Responsiveness Summary.

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XVI. SCHEDULE

Aoprove Remedial Action;
Sign Record of Decision

Commence Pemed ial Design
and Remedial Action of
Water Management alter-
natives

Week of September 22,
1986

Funding Pending
Reauthorization of
CERLCA

Once CERCLA has been reauthorized, the RD/RA phase for Iron
Mountain Mine is proposed to be implemented in the following
manner:

1. Pre-Design for all source control
and treatment components

2. Hydrogeologic investigation and
LDCC pilot and demonstration test

3. Remedial Design

a) Partial capping

b) Upper Slickrock Creek diversion

c) South Fort Spring Creek

diversion; and

d) Upper Spring Creek diversion

4. Remedial Action

a) Partial capping

b) Upper Slickrock Creek diversion

c) South Fort Spring Creek

diversion; and

d) Upper Spring Creek diversion

5. Remedial Design: LDCC (if feasible)

Richmond
Slimrock

6. Remedial Action: LDCC

Richmond
SIimrock

RD/RA: Lime Neutralization
(if needed)

FY 1987, 1st QTR
FY 1987, 1st QTR
FY 1987, 3rd QTR

FY 198T, 4th QTR

FY 1988, 1st QTR

FY 1988, 3rd QTR

FY 1989, 3rd QTR
FY 1990, 2nd QTR

FY 1991, 1st QTR
FY 1991, 3rd QTR

Will be determined
by results of LDCC
>ilot and demonstra-
tion tests.

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67 -

XVII. FUTURE ACTIONS

After this Record of Decision is signed, EPA will enter
into an Interagency Aqreement with the U.S. Bureau of Reclamation
(Bureau) for the design and construction of the source control
and treatment components of the selected remedial action. In
this manner, the Bureau will function in a role identical to that
of the U.S. Corps of Engineers under the Superfund program and
will oversee and manage the design and construction of the selected
remedial action. This agreement will build upon the national
interagency agreement between EPA and the Bureau for the cleanup
of NPL sites.

The Bureau will assist EPA's cleanup efforts by seeking
funding for the design and construction of the water management
components of the selected remedial action. 1PA may need to
advance Trust Fund monies to the Bureau to begin certain of these
activities so as to not interupt the site cleanup process. Under
the terms of the agreement, the Bureau will reimburse EPA for
these advanced monies.

Implementation of the selected alternative is expected to
proceed under a phased approach, with monitoring following the
construction of each component remedial action alternative.

This will allow EPA to fully determine the efectiveness of each
alternative. The phased approach will be implemented in the
following manners

OPERABLE UNIT

o Capping above Richmond orebody
Design - 6 months

Construction - 9 months (under suitable weather conditions)
o Surface Water Diversions
Design - 12 months
Construction - 18 months
o Enlargement of Soring Creek Debris Dam
Design - 18 months
Construction 18 months

(This component will not begin RD/RA until all the source
control, treatment (if needed) and water management components
have been constructed and monitored for their effectiveness).

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€8

o Richmond Hydroqeoloqic Investigation
The object of the investigation is tos

1. Identify the main sources of inflow and AMD to the
underground mine workings;

2. Determine the vertical and lateral distribution of
hydraulic head and permeability) and

3. Evaluate slope stability and the strength of geologic
material.

These objectives will be accomplished, in part, through a
groundwater drilling program and an assessment and survey
of the underground mine workings. This investigation may
identify another fill material or source control measures
that may be equally or better suited for the Iron Mountain
Mine site. Should this be the case. Region IX would propose
to expand the LDCC pilot test described below to include an
examination of these alternatives.

o Pilot and Demonstration Test of Low-Density Cellular Concrete

1. Pilot Test

The objective of this test is to determine the proper
formulation of LDCC to withstand attack and corrosion from
AMD. This will include a) laboratory test that will examine
the effects of acid attack on various cement and additives;
b) adhesion and fracture and interface leach tests to
determine the applicability of LDCC to an acid environment;
and c) determination of the geotechnical and hydrologic
characteristics of LDCC.

2. Demonstration Tests

A small-scale demonstration test, and possibly a larger-scale
test# will be conducted in the underground mine workings;
this will require the partial rehabilitation of the Richmond
adit. If a larger-scale test is deemed necessary, it will,
in all likelihood, be conducted in the Lawson portal; in
effect, this test will serve as the first phase of the
implementation of LDCC.

The final scope and cost of the ground water investigation
and the LDCC pilot and demonstration test are currently in
the process of being fully developed.

o Implement perimeter control as needed to minimise direct
contact threat.

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-• tun m CM*o»NiA-MfMTH *no witMK *«not Q HcxcVirflco 2.

OtOtOt BtWMtJIAN. fT. . ,

DEPARTMENT OF HEALTH SERVICES

TOXIC SUMTANCU CONTROl OIVtStON
NORTHERN CALIFORNIA MCTKM
«ase win inn roao

SACRAMENTO. CA M«M

September 11. 1988

Mr. Keith Takata. Chief

Superfund Profram Branch

Toxics and Waste Management Division ¦

U.S. Environmental Protection Agency

Region IX

215 Fremont Street

San Francisco. CA 94105

Dear Mr. Takata:

COMMENTS OH THE DRAFT RECORD OF DECISION FOR IRON MOUNTAIN MINI,
AUGUST, 1986

The Department of Health Services (DHS) has reviewed both the
Environmental Protection Agency's (EPA) Public Consent
Feasibility Study Addendum, July ^5. 1986 and the Draft Record of
Decision (ROD*. August. 1986 on Iron Mountain Mine. The former
report is an addendum ti the EPA Public Comment Feasibility Study
Report dated August 2, 1985. DHS agrees with the general approach
and strategy of EPA's recommended remedial action for Iron
Mountain Mine as outlined in the draft ROD, but we suggest
change, clarification or definition ^n some points.

The strategy calling for a phased implementation of several
operable units is in the best interest of the State. We
understand these units to be: partial capping of cracked and
caved ground areas above the Richmond orebody; surface w*ter
diversion .of Upper Spring Creek. South Fork Spring Creek and
Upper Sliekrock Creek; and enlargement of the Spring Creek Debris
Dam. The ROD should also include provisions for establishing base
line data on surface water measurement and sediment transport, in.
addition to the monitoring program assessing the impact of each
component before the next ij implemented. Further, a clearer
definition :f the areas tc- be included in the partial capping
alternative is necessary.

We support EFA"£ selecticn si the combined alternative number
nine :CA-9) because or" its presumably lower operation and
maintenance costs. We further concur that final eomftitreent to
injection of low density cellular concrete fLDCC) into the

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.1,1.

Mr. Keith Takata

under* I'-uni nine workings as * source control for xcii min-s
drainage sAMDJ be reserved until the results of the |»iiot »nd
demonstration tests pr:v- its feasibility. The ROD'S fround water
investigation to evaluate LDCC in.1ec.tion should be broadened to
include a hydrogeolcgic investigation of flow paths in the highly
fractured rock sones.

We recommend immediate implementation of operable units located
on or upstream of Iron Mountain Mine property which are
unaffected by the results of the pilot/demonstration testing of
the LDCC. We request, however, a more detailed analysis of the
costs to the Statu for implementation and operation and
maintenance of these units. Specifically. we need to know the
State's share of these costs for State fiscal years 1986-87 and
1£87-8?.

EPA should specif .* iu the ROD that additional remedies will be
implemented if site clean-up objectives are not met by the
proposed plans or if implementation of the plans creates a
condition of imminent and/or substantial endangerment.

Finally, the planning and design of the operable units and of the
LDCC pilot and demonstration tests must include a DHS input,
review and approval process.

AMD at Iron Mountain Mine poses a serious environmental threat,
and we look tcx-ward to working with EPA towards a solution.
F'lease direct future communication to the attention of:

Anthony J. Landis. P.E.. Chief
Site Mitigation Unit
Northern California Section
Department of Health Services
4250 Power Inn Read
Sacramento. CA 95626

If your staff have any questions regarding th»se comments, please
have them contact Caniace A. Mc^ahan sf :ur office at 'SIS:

3938.

ec: Mr. William Crooks, RWQC

County of Shasta, 0W# Padding

flames T. Axlen. Ph.D.

'fjhief. Northern California Section

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llT^ijnEiO*BCAUI^ ¦¦¦¦¦¦¦^

CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD-
CENTRAL VALLEY REGION

3301 S STKCET

SACRAMENTO. CALIFORNIA MtlfrTQSO
FHONK: tttCI 44S-0270

9 September 1986

Nr. Keith Takata, Chief
Environmental Protection Agency
Superfund Programs Branch (T-4)

Toxic Mast* Management Division
21S Framont Straat
San Francisco. CA 94105

FINAL COMMENTS - REMEDIAL INVESTIGATION/FEASIBILITY STUOY FOR IRON MOUNTAIN MINE

This letter contains the Regional Board staff's final comments and recomnenda-
tlons regarding a CERCLA cleanup program at Iron Mountain Mine. These comnents
and recommendations are based on our review of the Oecember 1984 Remedial
Investigation Report, the August 198S Feasibility Study* and the July 1986
Feasibility Study Addendum.

Our own goals and objectives for an acid mine drainage control program at Iron
Mountain Mine are as follows.:

1. Improve water quality in the Sacramento River downstream of Keswick
Dam so as to protect aquatic life and eliminate potential Impacts on
domestic water supplies In this portion of the river.

2. Improve water quality 1n lower Keswick Reservoir and the Spring
Creek watershed to restore some measure of beneficial uses 1n these
waters.

3. Implement a mine drainage control program which provides assurance
of long-term effectiveness with minimum operating and maintenance
needs. (The control program should not be dependent on future water
storage and dilution policies, and should consider the Inherent
Instability of the mountain area.)

In reviewing combined alternatives CA-1 through CA-9, we believe that Implemen-
tation of CA-9 would most effectively achieve the above-stated goals. We concur
with the phased approach to Implamentlng CA-9. Capping of the ground surface
over the Richmond ore body should be Initiated as soon as possible, as should
the recommended pilot studies needed to determine the feasibility of using low
density cellular concrete (LDCC).

We support a request for funding of the principle water management actions; the
upper and South Fork Spring Creek Diversions and enlargament of the Spring Creek
Oebrls Dam. The design studies for these facilities should proceed. However,

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Mr. Keith Takata

-2-

9 September 1986

we recommend that the diversion facilities on South Fork and upper Spring Creek
be designed with the capability of releasing water downstream to control pH 1n
lower Spring Creek and Spring Creek Reservoir. The need for pH control 1n
Spring Creek Reservoir will depend ultimately on the success of the source
control program, with adequate source control, 1t may be possible to raise the
pH to a level which would cause metal precipitation 1n Spring Creek Reservoir as
opposed to Keswick Reservoir, where metals currently precipitate. In addition,
any plan to construct water storage and diversion facilities for the purpose of
adequately diluting acid mine drainage would be inadvisable without a long-term
agreement with the Bureau of Reclamation concerning operation of these facil-
ities 1n conjunction with releases from Keswick and Shasta Dams.

We recommend that the upper Sllckrock Creek 01version be included In the initial
phase implementation only if Initial studies Indicate that the waste rock
material, which presumably produces the B1g Seep discharge, will not be used in
the formulation of the low density concrete.

To summarize, we recomnend that the Superfund cleanup program at Iron Mountain
Mine proceed as follows:

Phase 1

0 Surface capping of the ground overlying the Richmond ore body.

0 Pilot and demonstration studies on the feasibility of 10CC.

0 Request funding for water management alternatives and initial design
studies.

0 Evaluate water quality Impacts.

Phase II

0 Implement filling of the underground workings with LDCC 1f Phase I
studies Indicate effectiveness.

(or)

0 Implement alternative source control, such as 11me/l1mestone or other
treatment of major point sources.

0 Evaluate water quality Impacts.

Phase III

0 Complete water management alternatives (1f needed).

0 Evaluate water quality impacts.

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Mr. Keith Takata

-3

9 September 1986

In conclusion, we wish to express our appreciation for the efforts of your
agency and CH2M H111 In completing tha Remedial Investigation/Feasibility Study
and helping to resolve this long-standing water quality problem.

MilLIWI H. bKUUKd

Executive Officer

cc: U.S. Bureau of Reclamation, Sacramento

Department of Fish and Game, Region I, Redding
Department of Health Services, Sacramento

Water Resources Control Board, Division of Water Quality, Secramento
CH2M H111, Redding

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