-------
GENERAL RESPONSE
ACTIONS
REMEDIAL TECHNOLOGY
PROCESS OPTION
DESCRIPTION
SCREENING COMMENTS
| No Action f-
I CoMolnm«nl
Copping
Surfoct Control!
| C«os>nth«lle memtron«*
Orvertlon Sy»temi I
PntumolkOJty apcriM cannot! fc vttd to
limit ouMoc* lortlfolkjn on momtm pIlM.
I* u»d le limit lufloei kifflrvtlon an »*d.
Non-RCRA LondUII
Hatardeuo meUflol cqn b* tf1i»oi*d el
oil ilte (JflO mlM away) or ol e new foe Illy onsllt.
Nonhorafdowt motcriol eon be tflipoicd ol
ol'«ll« (tO miW» a*oy) » at « n«* foeftlr «n«'it«.
All opt ton • Of* f«loln«» inln» -otHnj*,
•hkh con no I procllcoblx be rehobtltated lo comply «llh fiCft*
All oplioo* o-r .eloVitd.
NOTES
1. TECHNOlOCItS AND PROCCSS OPHONS
SCRECNEO OUT ARC SHOWN WTH HAtCMlMC.
2. * SELCCTtD RCPRCSEMTAUVE PROCESS
OPTIONS FOR AUERNATltt: DEVtLOPMF.HT.
FIGURE?
SCREENING OF REMEDIAL
TECHNOLOGIES FOR WASTE PILE
(ROM MOUNTAIN MINE flOO
-------
The technologies and options that have been screened out because of inadequate
precedent or inadequate information about their application to the Iron Mountain
Mine site are shown by boxes with dashed lines. This screening is based largely upon a
judgment that existing information does not provide a strong or complete case for
successful application of this option. There is a possibility that additional information
about the site or other applications may justify a future reexamination of these options
and possibly their inclusion as part of adopted remedial alternatives.
The Feasibility Study addressed four basic alternatives for control of the portal AMD.
They are PO—No-Action, a mandated base-line alternative, PI—Treat Portal Flows
(with Simple Mix and HDS subalternatives), P2—Plug Mine, Internal Pool Treatment
and Treat Residual Flows, P5—Plug Mine, External/Internal Pool Treatment and Treat
Residual Flows, and P6—Cap and Treat Portal Rows (with Simple Mix and HDS subal-
ternatives). The main elements of these alternatives are described below.
VII.2 Alternative PO-No-Action
The "no-action" alternative, PO, is developed and evaluated as required by the NCP in
40 C.F.R. § 300.430(e)(6).
The no-action alternative is commonly used as a baseline alternative against which
other alternatives are judged. As the name implies, this alternative does not include
any additional remediation activities. The no-action alternative would include provi-
sions for limited monitoring, operation, and maintenance of the copper cementation
plants and operation and maintenance of the projects constructed pursuant to EPA's
1986 ROD.
Without further remediation, the AMD production and discharge at Iron Mountain is
expected to continue for centuries until such time as the sulfide-rich mineralization is
completely depleted. This geochemical process is expected to continue with the same
or similar pattern and intensity of the current discharges for the foreseeable future.
VIL3 Alternative PI-Treatment of Flows from Portals
The treatment alternative mitigates the effects of AMD discharges by collecting and
treating the AMD as it flows out of the Richmond and Lawson portals. The purpose
of treating the AMD is to neutralize the acidity and cause the heavy metals to precipi-
tate out of solution. The heavy metals-laden sludge derived from treatment plant
operations would require disposal and long-term management consistent with
applicable or relevant and appropriate regulations.
The treatment technology is well developed in general. At Iron Mountain, IC1A has
operated a simple-mix treatment plant and demonstrated capability of neutralizing
Richmond portal AMD flows and removing greater than 99 percent of the copper,
cadmium, and zinc. Treatment plants can be designed to meet various discharge stan-
10011108.RDD
37
-------
dards including stringent standards. Collection and treatment of AMD would not com-
promise the current nature of the AMD discharges as point source discharges.
The treatment alternative consists of the following components:
A system for collecting AMD flows from the Richmond and Lawson portals,
which includes the adits and facilities to physically collect the flows, prior to the
delivery system
Pumping stations and pipelines or gravity drainage pipelines to deliver the AMD
to the treatment plant
Equalization systems to provide for flow equalization and equalization of chemi-
cal constituents in the AMD
Treatment plant facilities
Sludge handling and disposal facilities
Monitoring
VII.4 Identified Treatment Options
A detailed evaluation of water treatment technologies that might be applicable for the
Iron Mountain site was performed. That evaluation identified three treatment
technologies that are considered to be viable options:
Simple mix precipitation using calcium hydroxide
Lime/sulfide high-density sludge (HDS) precipitation
Caustic precipitation
For purposes of evaluation, the peak design capacity of the treatment plant is assumed
to be 1,050 gpm. This anticipates simultaneous peak flows from the Richmond and
Lawson portals of 800 and 250 gpm, respectively. Annual average flow is assumed to
be 94 gpm, based on measured Richmond and Lawson portal flows.
Based on the available information, it is estimated the sludge from the lime/sulfide
HDS treatment process may result in a sludge of 50 percent solids with a bulk density
of nearly 95 pounds/cubic foot. Under these assumptions, approximately 30,000 cubic
yards of sludge would be produced annually and require disposal. Under the Simple
Mix treatment method outlined in the Proposed Plan, it is estimated that approximately
110,000 cubic yards of sludge would be produced annually and require disposal.
Brick Flat Pit will be modified for sludge disposal as a non-RCRA landfill, including a
landfill engineered to comply with California regulations governing mining waste
disposal. Conditions in Brick Flat Pit are expected to meet or surpass non-RCRA
10011108.RDD 38
-------
landfill requirements and may approach or approximate RCRA requirements with a
moderate level of modifications.
VII.S Alternative P2-ICIA Plugging Alternative
The plug and treat approach developed for consideration by ICIA relies upon improve-
ments to the mine facilities to assure containment and injection of neutralizing agents
into the mine workings to control the chemistry of the mine pool as it is formed. The
ICIA approach would also involve establishing a colony of microbes to aid in reducing
metal concentrations and oxygen content of the water in the mine pool. Table 4-3
from EPA's Feasibility Study provides a comparison of components of the various plug-
ging approaches considered. Figure 8 provides a simplified graphical depiction of the
mine workings and some of the key physical features related to plugging approaches.
Table 4.3
Components of the Plugging Alternatives
Component
Rehabilitate Mine
A-Drifl
B-Drift
C-Drift
2550 Substope
2650 Grizzly
Lawson Tunnel
Confidence Decline
Alternative Access to Lawson Decline Plugs
Backfill
D-Drift
Scott Platform
Abandoned Mine Borings
P2
Mine Plugging Witb
Internal Treatment
(ICIA Alternative)
•*•
•
o
•
•
o
o
*
P3
Mine Plugging
With Internal
Treatment
*
P4
Mine Plugging
With External
Treatment
•*•
PS
Mine Plugging
With External-
Internal Treatment
*
•
•
o
•
•
•
•
•
•
•
•
•
Grouting
Pillar Exploration and Grouting Test
Grout Curtain
Injection Wells
Lime Stowage
o
*
19
•
•
*
SO
•
*
*
25
o
•
*
40
o
Pumping Systems
Lawson -Brick Flat Pit
Richmond -Brick Flat Pit
Boulder Creek-Brick Flat Pit
Slickrock Creek-Brick Flat Pit
Confidence-Brick Flat Pit
Brick Flat Pit Treatment Plant
•
•
•
*
•*•
•
•
•
•
*
•*
•
•
•
•
*
*
•
•
»
•
*
*
•
Brick Flat Pit Improvements
Containment Embankment
Saddle Dike
Leacbate Drainage System
*
*
*
•
*
•
•
*
•
•
*
•
Monitoring Wells
10011108.RDD
39
-------
Table 4-3
Components of the Plugging Alternatives
Component
Pool
Pillar
Slope/Streams
Grout, Plug, and Pressure Test
Richmond Adit
Four Declines to Lawson Tunnel
Second Richmond Plug
Slope Monitoring
Stage Mine Filling
P2
Mine Plugging With
Internal Treatment
(ICIA Alternative)
4
6
4
•
•
O
•
•
P3
Mine Plugging
With Internal
Treatment
30
30
7
*
• '
*
•
•
P4
Mine Plugging
With External
Treatment
30
30
7
•
•
•*•
•
•
PS
Mine Plugging
With External-
Internal Treatment
30
30
7
•
•
*
•
•
• = included o = not included •*• = contingency
VII.6 Alternative P2-ICIA Plugging Alternative
Weston, 1991 a, describes the ICIA proposal as follows:
An initial dose of lime would be placed in the accessible passageways on the
2,600 and 2,650 levels to ensure that during the initial stages of filling, the mine
pool would not be at an extremely low pH. Also, where redissolved salts con-
tribute ferric and ferrous iron to the mine pool, contact with lime will cause the
iron to precipitate as an insoluble sludge, inhibiting the increased production of
AMD. In addition, during mine filling, a neutralizing agent (e.g., lime slurry,
soda ash, caustic) would be injected into the major stope areas to provide in situ
neutralization of the mine pool. Finally, a liquid high in organic carbon would
be injected to enhance the in situ microbial reduction of ferric iron and
dissolved oxygen, thereby preventing the production of AMD. This enhanced
microbial activity could also result in the precipitation of highly insoluble metal
sulfide sludge. Metals precipitated would include ferric and ferrous iron,
copper, cadmium and zinc.
This reference (updated pursuant to ICIA comments during the public comment period
and its April, 1992 Remedial Implementation Plan) provides the following additional
information on the details of the ICIA proposal implementation and operation:
Each of the decline plugs will be a pair of concrete plugs, which will be hydro-
statically tested.
The initial lime dose will be manually or mechanically placed to a depth of
several feet.
10011108.RDD
40
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SCHEMATIC STORE OF
RICHMOND ORE BODY
MATTIE MINE
LEGEND
• PLUG LOCATION
RDD69017.FS.RD SEPTEMBER 1992
FIGURES
PLUG LOCATIONS FOR THE
PLUGGING ALTERNATIVES
(ALTERNATIVES P3, P4, & P5
IRON MOUNTAIN MINE ROD
-------
An outside neutralization plant will be on "standby status" and "treatment of
mine discharges is not anticipated as part of this alternative."
A series of 21 injection wells will be installed to deliver neutralizing agent,
Boulder Creek water and AMD into the mine pool through the same injec-
tion system in cycles.
The Weston 1991b report provides some additional details of the ICIA proposal. The
key additional information includes:
A total of approximately 22,000 tons of lime will be placed in the drifts and blown into
nine slopes that are assumed to be uncollapsed.
Phase 1-22 percent pool, Elevation 2750, 6 months
Phase 2—50 percent pool, Elevation 2850, 18 months
Phase 3-100 percent pool, Elevation 3000, 24 months
Phase 4—Pool maintenance
The injection solutions will include soda ash and lime in the following estimated
quantities—1,500 and 3,000 tons, respectively, in Phase 1; 5,400 and 7,500 tons, respec-
tively, in Phase 2; and 8,500 tons of lime in Phase 3.
Vn.7 Alternative PS-Plug and External-Internal Treatment
EPA has developed the external-internal treatment alternative in response to technical
limitations that became apparent in the evaluation of plugging alternatives limited to
internal treatment or external treatment. Alternative P5 provides staged mine pool
filling, both external and internal treatment, and an operational flexibility to use these
methods sequentially and concurrently to achieve the best level of mine pool water
quality and to achieve the lowest level of environmental risk. The base plan, developed
to provide a basis for cost estimating, assumes initial use of only external treatment and
later concurrent external and internal treatment. The fully developed work plan would
have extensive field monitoring of the mine pool and seepage from the pool, a well-
developed set of guidelines for action during mine pool development and cleanup, and
operator flexibility to deal with both better-than-expected and worse-than-expected
developments. Lawson adit flows are treated by the external treatment plant.
Alternative P5 combines the attributes of Alternative P3, Plug and Internal Treatment,
and Alternative P4, Plug and External Treatment. The combination of treatment by
both external and internal (in situ) plant treatment provides the maximum opportunity
to attain good pool water quality early in the operation.
Alternative P5, Plug and External-Internal Treatment, is summarized as follows:
Richmond adit plug and four Richmond/Lawson decline plugs with appropriate
site testing and site improvements
10011108.RDD
42
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AMD conveyance system from Richmond and Lawson portals
Rehabilitation of the Richmond level including B-drift, C-drift, and possibly A-
drift
Backfill or partial backfill of the Richmond substopes, D-drift, and Scott plat-
form
Rehabilitation of the Confidence adit and Confidence/Richmond declines
Backfill of other mine openings and borings that could compromise the contain-
ment
Exploratory drilling and testing of the Richmond/Hornet pillar, and installing
minimum pillar grout curtain indicated by these tests
Pool and pillar monitoring wells
Slope inclinometer installations
Injection wells in the stopes, room and pillar, and drifts
Pumping wells for select removal of mine pool water for external treatment
Clean water supply system from Boulder Creek and Slickrock Creek
680-gpm treatment plant
System to prepare and circulate injection streams of clean water, recycled AMD,
and neutralizing solutions
Alternative P5 consists of plugging the mine to flood the workings above the Richmond
portal to the Confidence adit elevation. Filling is estimated to take approximately
5 years based on an average net fill rate of 60 gpm and a mine void volume of
480 acre-feet. Clean water would be continuously injected into the mine pool and
removed for treatment at a rate sufficient to maintain a dilution factor of approxi-
mately 10:1 within the pool as it fills to the 2875-foot elevation. It is anticipated that
when the pool has reached this elevation, sufficient control of the mine pool chemistry
will have been achieved to allow internal treatment using lime and soda ash to continue
until the mine is flooded to the Confidence adit (Elevation 3000). This scenario would
maintain a relatively dilute mine pool at all times during mine flooding, thus reducing
risks associated with leakage or plug failure.
10011108.RDD 43
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VII.8 Alternative P6- Cap and Treatment
Alternative P6 consists of placing a low permeability cap over the Richmond Mine and
providing treatment of the residual flows from the Richmond and Lawson portals. The
cap would cover the footprint of the mine and extend several hundred feet outside that
footprint to maximize capture of infiltration to the groundwater sink. The planimetric
area of the considered cap is about 23 acres with an estimated slope area of about
30 acres. The cap would range in elevation from 3440 feet to 3290 feet. It has been
concluded that a similar cap is not constructible over the Hornet Mine.
The existing terrain would be prepared for capping by clearing and grubbing the exist-
ing vegetation, removing loose overburden soils, compacting and fine grading of
exposed soil base materials, installing erosion control measures, and excavating a series
of access benches. The average depth of excavation exclusive of bench construction is
estimated to be 2 feet, and the exposed base material is expected to be lightly to
moderately weathered rock in 65 percent of the area and saprolite, landslide debris, or
fill in the remaining 35 percent. Benches are excavated at vertical intervals of about
50 feet over the cap area and have a steep cut slope of 1:1 to 2:1 (horizontal to
vertical). The benches would be aligned on the slope to provide access to all areas of
the slope and to direct runoff from the slopes to a central downslope drainage system.
The cap material may be shotcrete on a rock base and overlapping or "shingled" geo-
synthetic on soil base, or 65 percent shotcrete and 35 percent geosynthetic.
VII.9 Waste Pile Alternatives
The waste piles which will be addressed by these alternatives include WR-2, WR-12,
WR-13, WR-14, WR-17, WR-18, and WR-19. The alternatives considered in the
Feasibility Study were:
WO - No action. The waste piles would remain in place and would continue to release
hazardous substances.
Wl - Capping the wastes in place. Under this alternative, the waste piles would be
capped in place. They would not be consolidated.
W2 - Disposal in an off-site landfill. Under this alternative, the waste piles owuld be
excavated, transported to a landfill off-site, treated to fixate the waste materials, and
disposed of. The total volume of these wastes has been estimated to be approximately
30,000 to 50,000 cubic yards.
W3 - Disposal in an on-site landfill. Under this alternative, the wastes would be
consolidated and capped in an on-site location. Surface and groundwater flows would
be diverted from the landfill.
VIII. Summary of Comparative Analysis of Alternatives
The remedial alternatives developed in the Boulder Creek OUFS were analyzed in
detail for the Richmond and Lawson portal AMD discharges and the seven identified
10011108.RDD
44
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waste piles using the nine evaluation criteria specified by the NCP in 40 C.F.R. §
300.430(e)(9). The resulting strengths and weaknesses of the alternatives were then
weighed to identify the alternative for the portal AMD discharges and waste piles pro-
viding the best balance among the nine criteria. These criteria are (1) overall protec-
tion of human health and the environment; (2) compliance with applicable or relevant
and appropriate requirements (ARARs); (3) reduction of toxicity, mobility, or volume
through treatment; (4) long-term effectiveness and permanence; (5) short-term effec-
tiveness; (6) implementability; (7) cost; (8) state acceptance; (9) community
acceptance. Each of these criteria are described below.
VIIL1 Criterion 1-Overall Protection of Human Health and the Environment
Overall protection of human health and the environment addresses whether a remedy
provides adequate protection and describes how risks posed through each pathway are
eliminated, reduced, or controlled through treatment, engineering controls, or institu-
tional controls.
The Boulder Creek OU provides for an interim action that is not expected to be final,
and will not address all of the sources of contaminant discharges from the site.
Consequently, even though the remedial action will provide significant environmental
benefit, it is not expected to be fully protective of human health and the environment.
The remedial actions will address the two largest discharges at the site, the Richmond
and Lawson AMD discharges, and the discharges from seven waste piles, and will
provide a significant contribution toward the final site cleanup. The remedial actions
considered are intended to provide protection of human health and the environment
from the exposure pathway or threat being addressed by the Boulder Creek OU and
from the waste material being managed. The comparative analysis of the alternatives
is made on this basis and on the basis of their contribution toward meeting the final
cleanup goal.
Treatment of the acid mine drainage should contribute to protection of human health,
although this is not considered a major issue for either the No-Action or the action
alternatives. It is not considered a major issue because the concentrated acidic waters
are mainly limited to remote and uninhabited areas, these source areas have restricted
entry, and human exposure to the dilute waters is limited (Table 5-27).
Vin.1.1 Portal AMD Discharges
The level of environmental protection among the alternatives considered ranges from
limited to good. The No Action alternative provides only a continuation of the controls
now in place, namely the cementation plants, partial cap, and the Spring Creek and
Slickrock Creek Diversions. Effluent from the cementation plants will continue with
undiminished zinc and cadmium, significantly reduced amounts of copper, and a low
pH. The treatment alternatives, PI and P6, provide at least 99 percent removal of all
the metals and pH control. The plug-and-treat alternatives, P2 and P5, provide at least
good short-term protection from both metals and low pH waters, but the longer range
10011108.RDD
45
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value of the plug-and-treat alternatives will depend on the control of mine pool
chemistry and the effectiveness of the containment. Alternative P5 has a better chance
to provide good overall environmental protection.
In summary, the No-Action alternative provides inadequate environmental protection;
the plug-and-treat alternatives, P2 and P5, provide uncertain protection; and the
treatment alternatives, Pl-A, Pl-B, and P6, provide for a significant improvement in
protection for aquatic resources. The treatment only alternatives provide similar risks,
but Alternative Pl-B generates sludge which is physically and chemically more stable
than the Alternative Pl-A sludge. The cap of Alternative P6 will have a new visual
impact which will change in detail the skyline visible from the north side of Redding.
VIIL1.2 Waste Piles
The no-action alternative provides only a continuation of the controls now in place and
inadequate protection. The waste piles will continue to discharge AMD and to erode
into surface waters. Both action Alternatives W2, Removal, Treatment, and Disposal,
and W3, Excavation, Consolidation and Capping, will provide for protection of human
health and the environment from this exposure pathway by essentially eliminating the
discharge. Alternative W2 would provide for additional protection resulting from
treatment of the waste piles prior to disposal, but this additional protection may not be
significant relative to that provided by Alternative W3.
^ Table 5-27
Summary of Overall Protection of Human Health and the Environment
PO
Pl-A
Pl-B
P2
No-Action
Treat Portal Flows
Simple Mix
Treat Portal Flows
HDS
Plug Mine
Internal Pool
Treatment
Treat Residual
Flows
• Human health risk likely to be low.
• Present environmental impacts are likely to continue and may
increase in severity with prolonged exposure to contaminated
water and increased volume of contaminated sediments.
• Cementation removes about 95 percent of the copper, but does
not remove other metals or reduce acidity.
• Human health risk likely to be low.
• Significant reduction in environmental impacts with greater than
99 percent reduction in metals and the acidity of portal flows.
• Sludge from treatment requires containment to avoid new
exposure.
• Similar to Alternative Pl-A.
• Human health risk likely to be low.
• Level of environmental protection may be good or poor
depending on the effectiveness of mine pool chemistry controls
and the effectiveness of rock containment.
10011108.RDD
46
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P5 Plug Mine
External/Internal
Pool Treatment
Treat Residual
Flows
Human health risk likely to be low.
Level of environmental protection may be good or poor
depending on the effectiveness of controls of mine pool chem-
istry and the effectiveness of rock containment.
Risk of poor protection with P5 is less than P2 because of better
pool conditioning and a specific plan to limit or drain the mine
pool.
P6 Cap and Treat Portal
Flows
Human health risk likely to be low.
Significant reduction in environmental impacts with greater than
99 percent reduction in metals and the acidity of portal flows.
Sludge from treatment requires containment to avoid new
exposure.
Table 5-36
Summary of Overall Protection of Human Health and the Environment
Alternatives
WO No-Action
W2 Waste Pile Removal,
Treatment, and Disposal
W3 Consolidating and
Capping Waste Piles
Onsite
Overall Protection of Human Health
and the Environment
• Human health risk likely to be low.
• Present environmental impacts are likely to continue and may
increase in severity with prolonged exposure to contaminated
water and increased volume of contaminated sediments.
• Human health risk likely to be low.
• Significant reduction in environmental impacts with up to
99 percent reduction in metals and the acidity of portal flows.
• Sludge from treatment requires containment to avoid new expo-
sure.
• Similar to Alternative W3.
VIII.2 Criterion 2—Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs)
Applicable requirements are those cleanup standards, standards of control, and other
substantive requirements, criteria, or limitations promulgated under Federal or State
environmental or facility siting laws that specifically address a hazardous substance,
pollutant, contaminant, remedial action, location, or other circumstance at a CERCLA
site. Relevant and appropriate requirements are those cleanup standards, standards of
control, and other substantive requirements, criteria, or limitations promulgated under
Federal or State environmental siting law that, while not "applicable" to a hazardous
substance, pollutant, contaminant, remedial action, location, or other circumstance at a
CERCLA site, address problems or situations sufficiently similar to those encountered
at the CERCLA site that their use is well suited to the particular site.
10011108.RDD
47
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Compliance with ARARs addresses whether a remedy will meet all Federal and State
environmental laws and/or provide a basis for a waiver from any of these laws. These
ARARs are divided into chemical-specific, action-specific, and location-specific groups.
The Boulder Creek OU provides for an interim action that it is not expected to be final
and does not address all of the sources of discharges from the site. Therefore, it is not
expected to fully comply with all ARARs with respect to water quality standards for
metals concentrations in surface waters and State Fish and Game standards. Although
the remedial actions evaluated in the Boulder Creek OUFS provide for significant
improvement by essentially eliminating the two largest discharges from the site, EPA is
relying upon the ARAR waiver for "Interim Measures" (40 C.F.R. § 300.430
(f)(l)(ii)(C)(i) for remedy selection with respect to the Boulder Creek OU and
therefore is waiving the the Regional Board Basin Plan water quality objectives and the
Fish and Game § 5650 standards which would necessitate elimination of all releases as
ARARs for this operable unit. EPA's overall goal at the site remains achieving these
water quality objectives and Fish and Game standards. The alternatives for this
Operable Unit otherwise will comply with ARARs, including ARARs for sludge
disposal.
VIII.2.1 Portal AMD Discharges
The treatment and cap and treat alternatives will make a significant contribution in the
goal of complying with water quality standards. The plug-and-treat alternatives, P2 and
P5, are less certain and they may or may not make a significant contribution depending
on the development of nonpoint source leaks and the water quality in these leaks. If
fully effective, the plug-and-treat alternatives would provide comparable compliance
with ARARs.
10011108.RDD
48
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Table 5-28
Summary of Compliance with ARARs
PO
No-Action
• Will not meet ARARs.
Pl-A Treat Portal Rows
Simple Mix
This interim action will not provide full compliance with
ARARs.
The large anticipated reduction in metals in the dis-
charges is a significant contribution to final cleanup
standards for the site.
Pl-B Treat Portal Flows
HDS
Similar to Alternative Pl-A.
Improved sludge characteristics over Pl-A may facilitate
compliance with disposal ARARs.
P2 Plug Mine
Internal Pool Treatment
Treat Residual Flows
This interim action will not provide full compliance with
ARARs.
May have a small or large reduction in metals and no
contribution or a significant contribution to final
cleanup standards for the site.
P5 Plug Mine
External/Internal Pool
Treatment
Treat Residual Flows
This interim action will not provide full compliance with
ARARs.
May have a small or large reduction in metals and no
contribution or a significant contribution to final
cleanup standards for the site.
P6 Cap and Treat Portal Flows
This interim action will not provide full compliance with
ARARs.
The large anticipated reduction in metals in the dis-
charges is a significant contribution to final cleanup
standards for the site.
ARARs are discussed in greater detail in the Feasibility Study for the Operable Unit.
Except for the no-action alternative, which generally fails to comply with ARARs, the
Feasibility Study did not demonstrate any important differences in compliance with
ARARs among the various alternatives. It is anticipated that the lower leachability of
the HDS treatment sludges over the Simple Mix treatment will make it easier to
comply with Regional Board regulations governing disposal of mining waste.
Vin.2.2 Waste Piles
All of the alternatives for waste piles will fall short of meeting ARARs in the receiving
waters because of the Boulder Creek Operable Unit does not contain all of the con-
taminant sources and these alternatives address only a part of the sources in the
Boulder Creek Operable Unit (Table 5-37). The action alternatives are interim
measures with a best case expectation of making a significant contribution toward final
cleanup.
10011108.RDD
49
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Table 5-37
Summary of Compliance with ARARs
Alternatives
WO
W2
W3
No- Action
Waste Pile Removal,
Treatment, and Disposal
Consolidating and Capping
Waste Piles Onsite
Compliance with ARARs
• Will not meet ARARS.
• This interim action will not provide full compliance
with ARARs.
• The small anticipated reduction in metal discharges is
a significant contribution to final cleanup standards
on the site.
• This interim action will not provide full compliance
with ARARs.
• The small anticipated reduction in metal discharges is
a significant contribution to final cleanup standards
on the site.
VIII.3 Criterion 3-Long-Term Effectiveness and Permanence
Long-term effectiveness and permanence refers to the ability of a remedy to maintain
reliable protection of human health and the environment over time. This criterion
includes the consideration of residual risk and the adequacy and reliability of controls.
VHI3.1 Portal AMD Discharges
The plug-and-treat alternatives, P2 and P5, are the only options with the potential to
slow or halt the geochemical reactions forming AMD (Table 5-30). However, their
long-term effectiveness is uncertain because their success depends on certain natural
conditions (e.g., low rock permeability) being optimal, and these natural conditions are
only partly known. In addition, some aspects of the proposed activities have few
precedents. Although both are uncertain, the potential for success of plug-and-treat is
judged to be higher for P5 than for P2 because of operational flexibility of the former
option.
Based upon current knowledge of mine conditions, the potential for complete control
of AMD formation in the Richmond Mine is judged to be low for both P5 and P2.
Furthermore, even if partially effective, AMD generation may resume if the mine pool
is lowered or drained at some future date. The plug-and-treat alternatives may lead to
leakage into the Hornet Mine but are unlikely to affect the ongoing AMD generation.
It is expected that Lawson adit flows will impose an ongoing and potentially permanent
treatment requirement irrespective of the success or failure of plug-and-flood in the
Richmond Mine.
The treatment options, Pl-A and Pl-B, control the contaminated flows and have no
effect on the geochemical reactions. They provide a dynamic balance which can be
effective as long as treatment and sludge disposal resources are provided. The cap and
10011108.RDD
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treat alternative, P6, includes a cap to control infiltration, which is a major source of
the water to form new AMD, and a treatment program to deal with continued
Richmond portal flows and the Lawson portal flows. The cap is expected to have value
to reduce peak flows from the Richmond portal and to reduce the average Richmond
portal flow by between 50 and 80 percent. The effectiveness of the P6 plant should be
equal to and perhaps a little better than Pl-A and Pl-B, as the former plant does not
have to deal with peak flows.
A prediction of the long-term effectiveness of the plugging alternatives must rest on an
informed judgment based upon what is reliably known about the site conditions and
what can be learned from other plugged mines with similar geology. Many of the
technical factors related to successful implementation of the various plugging
approaches require further development through bench-scale and large-scale studies,
field studies and field testing. Rehabilitation of portions of the mine workings is
required. EPA considers that this information is required to provide reliable
information that is not presently available and related to key technical considerations.
EPA has reviewed other plugging actions (including those at the Eagle Mine in
Colorado and the Lokken Mine in Norway) and has concluded that site specific factors
related to geology, geochemistry and hydrology are central to success in mine plugging
as a remedial approach.
The treatment alternatives, Pl-A, Pl-B, and P6, will be effective as long as treatment is
maintained. Becaus_e Pl-A and Pl-B do not reduce or eliminate the AMD-forming
reactions, they cannot be expected to improve the quality of the discharges.
Alternative P6 may be combined with additional controls or itself may impact the
chemistry of the discharge by its alteration of the hydrologic regime in quantity of flows
or their peak nature. The differences between these alternatives may be significant
with respect to cost but are not large with respect to effectiveness. Alternative P6 may
offer opportunities to implement further source control technologies for the Richmond
Mine. Alternative P5 is a source control for an "ultimate solution" experiment for the
Richmond Mine buf Ttoes not appear to be the solution for the Lawson portal flows.
10011108.RDD
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The conclusion that Alternative P5 will require a treatment plant for the Lawson portal
flows should be balanced against its potential for stopping Richmond portal flows.
Table 5-30
Summary of Long-Term Effectiveness
PO
Pl-A
Pl-B
P2
P5
P6
No- Action
Treat Portal Flows
Simple Mix
Treat Portal Flows
HDS
Plug Mine
Internal Pool
Treatment
Treat Residual
Flows
Plug Mine
External/Internal
Pool Treatment
Treat Residual
Flows
Cap and Treat
Portal Flows
• Not effective long-term or short-term.
• Metals releases and current risks may continue for thousands of
years.
• Effective in short-term and long-term for a wide range of flow
quality.
• Expect 99 percent reduction in metals from portal flows.
• Little uncertainty about results.
• Treatment is a dynamic mitigation controlling the contaminant
stream but not the source geochemical reactions.
• Sludge disposal becomes a major cost consideration in 60 to 100
years.
• Same as Alternative Pl-A except sludge disposal would not become
a major cost consideration until approximately 120 to 200 years.
• Effectiveness depends on (1) successfully flooding the mine, (2)
permanent mine pool neutralization, (3) mine pool uncomaminated
by metals-laden infiltration, (4) mine pool exfiltration is uncontami-
nated, and (5) Lawson flows cease or are metals-free.
• There is uncertainty about the results, but the potential for success
is judged to be low.
• Success would provide source control.
• Acid generation may resume if mine pool is lowered or drained. J
• Effectiveness depends on (1) successfully flooding the mine, (2) |
permanent mine pool neutralization, (3) mine pool uncomaminated
by metals-laden infiltration, (4) mine pool exfiltration is uncontami-
nated, and (5) Lawson flows cease or are metals-free.
• Result uncertain, but potential for success is judged to be low. I
• Success would provide source control.
• Acid generation may resume if mine pool is lowered or drained.
• Effective indefinitely provided cap maintained and treatment pro-
vided.
• Expect portal flows to be reduced by 50 to 80 percent
• Treatment is dynamic mitigation, which controls contaminant
streams and not the source geochemical reactions.
• Sludge disposal in Brick Flat Pit becomes a major cost factor in
approximately 120 to 200 years (Simple Mix) or approximately 240
to 400 years (HDS).
• Capping is expected to be only partially successful at controlling
the AMD-forming reactions. J
VIII3.2 Waste Piles
Alternative W2 is ranked slightly higher than Alternative W3 because the waste rock
would be physically removed from the OU and would have no chance of contaminating
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Boulder Creek in the future. EPA expects that the disposal of the waste piles in
accordance with Alternative W2 would result in essentially permanent storage of the
metals in a capped and well-maintained offsite landfill. However, EPA also expects
that a capped and well maintained on-site landfill would also provide essentially
permanent storage of the metals in Alternative W2. See Table 5-38.
Table 5-38
Summary of Long-Term Effectiveness and Permanence
Alternatives
WO No-Action
W2 Waste Pile Removal,
Treatment, and Disposal
W3 Consolidating and
Capping Waste Piles
Onsite
Long-Term Effectiveness and Permanence
• Not effective long-term or short-term.
• Effective in short-term and long-term.
• Anticipate that the treated waste will have high stability.
• Anticipate a well-maintained landfill site will provide
essentially permanent storage.
• Effective in short-term and long-term.
• Anticipate a well-maintained landfill site will provide
essentially permanent storage with a somewhat higher risk
of future contamination to Boulder Creek than Alternative
W3.
VIII.4 Criterion 4-Reduction of Toxicity, Mobility, or Volume through Treatment
Reduction of toxicity, mobility, or volume through treatment refers to the preference
for a remedy that uses treatment to reduce health hazards, contaminant migration, or
the quantity of contaminants at the site.
Vm.4.1 Portal AMD Discharges
Alternative PO, the No-Action alternative, is not expected to provide a reduction in
toxicity, mobility, or volume because the source geochemical reactions in the Richmond
Mine and Hornet Mine are likely to continue for hundreds and perhaps thousands of
years (Table 5-31).
The treatment alternatives, Pl-A, Pl-B, and P6, will decrease the toxicity and volume
of the discharges and will reduce the mobility by separating and binding the metals in
sludge and storing the sludge in a landfill to limit future remobilization. Alternatives
Pl-B and P6-B with lime/sulfide HDS treatment are somewhat superior to the other
treatment alternatives because they produce a smaller volume of less leachable sludge.
The plug-and-treat alternatives can, in the best case, provide the ultimate reduction of
toxicity and volume by permanently stopping the production of metals-laden AMD in
the Richmond Mine but not the Hornet Mine. The potential for such a favorable
result for either P2 or P5 is judged to be low. If the best case is realized, the remaining
10011109.RDD
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issues are the mobility of acid water and metals trapped within the mine and the
continued treatment of Lawson portal flows. Alternative P5 offers the possibility that
the trapped metals may not be significant. If the plug-and-treat alternatives in the
Richmond Mine are not completely successful, the issues are likely to be treatment of
the Lawson portal flows, treatment of Richmond Mine pool, and collection and treat-
ment of exfiltrating waters in the mine pillars. The new mobility of potentially acid and
metals-bearing water and the possibility that monitoring systems and control systems
may be inadequate to control the new condition are serious risks inherent in the plug-
and-treat alternatives.
Table 5-31
Summary of Reduction of Toxicity, Mobility, or Volume
PO
Pl-A
Pl-B
P2
P5
P6
No-Action
Treat Portal Flows
Simple Mix
Treat Portal Rows
HDS
Plug Mine
Internal Pool Treatment
Treat Residual Flows
Plug Mine
External/Internal Pool
Treatment
Treat Residual Rows
Cap and Treat Portal
Rows
• Cannot expect reduction in toxicity or volume in the near
future.
• Increased environmental impacts may result from the same
discharges because of prolonged exposure and increased
sediment accumulations.
• Treatment and good containment of sludge can reduce
metal discharges from portals by 99 percent.
• Metals releases from sludge landfill are controlled by the
sludge alkalinity and site underdrain system. ||
• Similar to Alternative Pl-A, except that treatment method
will result in lower volume and toxicity sludge. ||
• Reduction in toxicity and volume depends upon the effec-
tiveness of well injections.
• In situ neutralization and metal precipitation are likely to
be less efficient and effective than in a treatment plant, and
pool quality is difficult to monitor.
• Mobility of mine pool metals is greater than in sludge or
portal flows.
• In-mine sludge storage may be less secure than storage in II
landfill.
• Reduction in toxicity and volume depends upon the effec-
tiveness of external and internal treatment.
• Neutralization and metals removal likely to be better than
Alternative P2.
• In-mine sludge storage may be less secure than sludge stor-
age in landfill, but this risk is likely to be lower than with
Alternative P2.
• Treatment and good containment of sludge can reduce
metal discharges by 99 percent.
• Metals releases from sludge landfill are controlled by the
sludge alkalinity and site underdrain system. j
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VIII.4.2 Waste Piles
Alternative, WO-No-Action, is not expected to provide a reduction in toxicity, mobil-
ity, or volume because field observations suggest that the waste rock piles have a large
amount of unreacted sulfides. Alternatives W2 and W3 are expected to be very similar
with respect to reducing mobility. The fixation treatment process of Alternative W2
will increase the volume of waste material but leave the volume of metals and the
toxicity unchanged. Alternative W3 will not affect the toxicity or volume of metals.
See Table 5-39.
Table 5-39
Summary of Reduction of Toxicity, Mobility, or Volume
Alternatives
WO No-Action
W2 Waste Pile Removal,
Treatment, and Disposal
W3 Consolidating and
Capping Waste Piles
Onsite
Reduction of Toxicity, Mobility, or Volume
• Cannot expect reduction in toxicity or volume in the near future.
• Increased environmental impacts may result from the same
discharges because of prolonged exposure and increased sediment
accumulations.
• Toxicity will remain unchanged.
• Mobility to Boulder Creek is eliminated, while fixation and
landfilling makes the risk of future mobility unlikely.
• The volume of waste material is increased, but the quantity of
metals is unchanged.
• Toxicity will remain unchanged.
• Mobility of the waste rock in landfill will be significantly lower
than the existing condition but greater than Alternative W2.
• The volume of waste rock and metals is unchanged.
MILS Criterion 5-Short-Term Effectiveness
Short-term effectiveness refers to the period of time needed to complete the remedy
and any adverse impacts on human health and the environment that may be posed
during the construction and implementation of the remedy.
VIII.5.1 Portal AMD Discharges
Alternative PO, the No-Action alternative, does not meet the remedial action objectives
and does not mitigate the present environmental risks as noted in Table 5-32.
The treatment alternatives, Pl-A, Pl-B, and P6, and the plug-and-treat alternatives, P2
and P5, all have a high potential short-term effectiveness because the treatment alter-
natives treat all Richmond portal and Lawson portal flows while the plug-and-treat
alternatives capture all Richmond portal flows and treat Lawson portal flows. The
plug-and-treat alternatives may be viewed as even slightly better than the treatment
alternatives because they do not require the treated water, with very small quantities of
residual metals, to be discharged into Boulder Creek.
10011109.RDD
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The treatment alternatives share the common short-term advantage that the process
can be readily changed to take advantage of improvements in treatment technology or
changed economic conditions which may in the future favor resource recovery pro-
cesses. The treatment plant for the plug-and-treat alternatives could likewise be
changed, but the large investment in preparing the mine for flooding and changes to
the mine during flooding could delay or eliminate modifications attractive under the
treatment on]y alternatives.
The chief short-term concerns for the plug-and-treat alternatives are continued AMD
production which complicates or compromises mine pool conditioning and poor
containment which allow excessive exfiltration and the risk of contaminated, nonpoint
source discharges in Boulder Creek or Slickrock Creek valleys. The pool chemistry and
containment risks will be uncertainties until operational experience is developed with at
least a partly filled mine. In addition, both plug-and-treat alternatives involve under-
ground construction for mine rehabilitation and therefore pose some risk of injury due
to caving ground, contact with highly acidic water, and exposure to potentially toxic or
harmful gas.
Table 5-32
Summary of Short-Term Effectiveness
PO No-Action
Does not meet remedial action objectives.
Does not mitigate risks.
PI-A Treat Portal Flows
Simple Mix
• Provides an immediate 99 percent reduction in metals
discharge from portals.
Provides significant reduction in metals to the Sacramento
River.
• No unusual worker or environmental risks during construction.
Pl-B Treat Portal Flows
HDS
• Similar to Alternative Pl-A.
P2 Plug Mine
Internal Pool Treatment
Treat Residual Rows
Provides an immediate 100 percent reduction in metals
discharge from portals.
Provides significant reduction in metals to the Sacramento
River.
Metals may reappear in small or large quantities as nonpoint
sources if mine pool chemistry is not controlled, or
containment is poor, or both adverse conditions are
encountered.
No practical controls for nonpoint sources have been
identified.
Mine rehabilitation may involve unusual risk to workers.
10011109.RDD
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Table 5-32
Summary of Short-Term Effectiveness
P5 Plug Mine
External/Internal Pool
Treatment
Treat Residual Flows
Provides an immediate 100 percent reduction in metals
discharge from portals.
Provides significant reduction in metals to the Sacramento
River.
Metals may reappear in small or large quantities as nonpoint
sources if mine pool chemistry is not controlled, or
containment is poor, or both adverse conditions are
encountered; risk is lower than Alternative P2, but may be
significant.
No practical controls for nonpoint sources have been
identified.
Mine rehabilitation may involve unusual risk to workers.
P6 Cap and Treat Portal
Flows
• Provides an immediate 99 percent reduction in metals
discharge from portals.
• Provides significant reduction in metals to the Sacramento
River.
• No unusual worker or environmental risks during construction.
Vni.5.2 Waste Piles
Alternative WO, the No-Action alternative, does not meet the remedial action objec-
tives and does not mitigate the present environmental risks (Table 5-40).
Alternative W2 is ranked slightly higher than Alternative W3 because the waste rock
would be physically removed from the OU and would have no chance of contaminating
Boulder Creek in the future. Expect the short-term effectiveness of the two alter-
natives to be essentially identical. The construction operations for both alternatives
would involve some risk of worker exposure. Alternative W2 has the additional small
risk of public exposure to the waste rock in transit through populated areas of Shasta
County.
Table 5-40
Summary of Short-Term Effectiveness
Alternatives
WO No-Action
W2 Waste Pile Removal,
Treatment, and Disposal
W3 Consolidating and
Capping Waste Piles
Onsite
Short-Term Effectiveness
• Does not meet remedial action objectives.
• Does not mitigate risks.
• Limited traffic impacts on the community and risk to workers
during construction.
• Will provide, at least by the next rainy season, an estimated 1
10 percent reduction in metals loading to Boulder Creek.
• Limited risk to workers during construction.
• Will provide, at least by the next rainy season, an estimated 1
10 percent reduction in metals loading to Boulder Creek.
• Small risk of future leaching of metals from the onsite landfill
to
to
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VIII.6 Criterion 6-Implementability
Implementability refers to the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to implement the chosen
solution. It also includes coordination of Federal, State, and local governments to clean
up the site.
VIII.6.1 Portal AMD Discharges
The No-Action alternative, Alternative PO, requires the least effort and is readily imple-
mentable (Table 5-33).
The treatment alternatives, Pl-A and Pl-B, are readily implementable because they
involve only flow control, treatment, and sludge disposal facilities. All of these facilities
involve well established technologies with known costs, effectiveness, and reliability.
The cap and treat alternative, P6, has similar treatment and sludge control require-
ments and, in addition, the construction and maintenance of a cap. The proposed shot-
crete cap involves an established technology used to protect slopes. The proposed
shotcrete cap is an unusual application of this technology with respect to both the size
of the cap and its purpose of reducing infiltration. Alternative P6 has the same high
implementability as Pl-A and Pl-B because it provides complete treatment of portal
discharges. The enhancement of providing a cap to reduce the Richmond portal flow
is a secondary aspect which trades increased capital investment to potentially achieve
an even greater reduction in operational costs.
The plug-and-treat alternatives, P2 and P5, have moderate to high risk of problems
which can affect their successful implementation. Although plug-and-flood is a
conventional approach with mixed success in AMD remediation in a variety of geologic
settings, the proposed plug-and-flood alternatives with mine pool conditioning are an
experimental approach with no apparent precedent. These proposals also have a
number of known technical problems, and pose the risk of creating new sources of con-
tamination. The areas which may affect success include containment, control of mine
pool chemistry, construction and operation of deep injection wells in caved and other-
wise disturbed ground above the mine, and problems associated with the administration
of a plug and mine-flooding activity. It is unlikely that a complete implementation plan
can be developed ahead of the work including all the control and contingencies neces-
sary to safeguard the environment. A rigid plan for a plug-and-treat alternative is very
likely to be unsuccessful. The best opportunity for success is to develop a flexible base
plan, implement controls and contingencies as verified by field observation and testing,
and provide a management plan with the authority to make appropriate changes and
even the authority to cancel plug and treat and move to another option.
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Table 5-33
Summary of Implementability
PO
No-Action
Readily implementable.
PI-A Treat Portal Flows
Simple Mix
Readily implemented as it uses established technologies with
known costs, effectiveness, and reliability.
Onsite sludge disposal appears practical for as long as 100 years.
Action is reversible and does not preclude implementation of
other alternatives or resource recovery.
Maintains point source nature of the discharge.
Pl-B Treat Portal Rows
HDS
Readily implemented like Alternative Pl-A but with newer tech-
nology.
Produces smaller amount of less leachable sludge than Alterna-
tive Pl-A.
Like Alternative Pl-A, reversible and maintains point source
nature of the discharge.
P2
Plug Mine
Internal Pool
Treatment
Treat Residual
Flows
Moderate to high risk of implementation problems.
Technical concerns with containment, chemical control of mine
pool, construction and operation of injection wells, and control
of Lawson portal discharges.
Administrative concerns with monitoring and performance
standards.
May create a nonpoint discharge.
Extends the life of onsite sludge disposal by factor of 3 or more.
Mine plugging by sludge may preclude future resource recovery.
P5 Plug Mine
External/Internal
Pool Treatment
Treat Residual
Flows
Moderate to high risk of implementation problems.
Technical concerns with containment, chemical control of the
mine pool and injection wells; chemical control is more likely
with P5 than with P2.
May create a nonpoint discharge.
Extends the life of onsite sludge disposal by factor of 3 or more.
P6
Cap and Treat
Portal Flows
Low risk of cap implementation problems due to slopes and
subsidence.
Cap will have some small impact on skyline views from the
north side of Redding.
Treatment is readily implementable.
Extends the life of onsite sludge disposal by factor of 2 or more.
Vm.6.2 Waste Piles
Alternative WO, the No-Action alternative, requires no specific future action
(Table 5-41).
Alternatives W2 and W3 are considered implementable as the required work of exca-
vation, transportation, and landfill construction for each alternative and waste rock
treatment in the case of Alternative W2 uses well established technologies. Steep
terrain and poor access will make some of the excavation work challenging and it is
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possible that some part of the waste rock will be left in place because of construction
limitations. Alternatives W2 or W3 will be successful if the major part of the waste
rock is removed.
Table 5-41
Summary of Implementability
Alternatives
WO No-Action
W2 Waste Pile Removal,
Treatment, and
Disposal
W3 Consolidating and
Capping Waste Piles
Onsite
Implementability
• Not applicable.
• Excavation can be performed with existing technology but steep
slopes and limited access will make some of the work challenging.
• Transport and landfilling are well established activities.
• May adopt a relative new treatment method but bench testing
should remove most uncertainties respecting implementation.
• Excavation can be performed with existing technology but steep
slopes and limited access will make some of the work challenging.
• Transport and landfilling are well established activities.
VHI.7 Criterion 7-Cost
This criterion examines the estimated costs for each remedial alternative. For com-
parison, capital and annual O&M costs are used to calculate a 30-year present worth
cost for each alternative.
Vffl.7.1 Portal AMD Discharges
Table 5-34 presents estimates of the 30-year present worth for the alternatives. The
table shows the present worth of the initial capital investment, 30 years of operation
and the total 30-year cost. The 30-years' basis is selected merely to compare the early
costs of all alternatives. All of the alternatives are expected to have costs beyond 30
years because present information shows that contaminated Lawson portal flows will
continue beyond 30 years. In most, if not all alternatives, contaminated Richmond por-
tal flows will also continue beyond 30 years, adding to the treatment burden.
The total present worth costs range from $40.4 million for Pl-A, Treat Portal Flows, to
$61.6 million for Alternative P5. Alternatives Pl-B, P2, and P6-A are in the middle of
this cost range, and Alternative P6-B is near the top of the cost range. It should be
noted that all of these cost estimates are the product of "order of magnitude" estimat-
ing procedures based upon conceptual layouts and preliminary cost information. Esti-
mates of this nature are subject to large changes with more detailed engineering and
cost information. It is commonly assumed that actual cost may vary from the stated
amounts by as much as plus 50 percent and minus 30 percent. With this level of uncer-
tainty in the cost estimates and given the similarity in the estimating results, it appears
that cost is not a dominating criterion in ranking the alternatives.
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EPA has revised its proposed plan cost estimates in response to two general issues
identified in public comments:
Commenters identified work items for which they felt EPA's estimates were too
low. Upon review, EPA identified two specific items for which EPA agrees that
the original cost estimates were too low. These two items are roadway
improvements and supply of electricity to the treatment facility. EPA has
recalculated the costs for these work items.
Commenters identified reliable operation of the treatment plant as a concern.
EPA reviewed factors associated with assuring reliable performance and
concluded that modifications to the proposed pipeline routing and pump
specifications were necessary with respect to assuring reliable performance.
EPA recalculated the associated costs.
The revised treatment cost estimates impact each of the alternatives under
consideration because they all rely on treatment in some capacity. The relative costs of
the alternatives have remained consistent.
Table 5-34
Summary of Costs
Alternatives
PO No-Action
Pl-A Treat Portal Flows
Simple Mix
Pl-B Treat Portal Flows
HDS
P2 Plug Mine
Internal Pool Treatment
Treat Residual Flows
P5 Plug Mine
External/Internal Pool
Treatment
Treat Residual Flows
P6-A Cap and Treat Portal
Flows
Simple Mix
P6-B Cap and Treat Portal
Flows
HDS
Present Worth Basis
Capita! Costs ($)
18,798,000
23,133,000
27301,000
38,985,000
31,123,000
34,166,000
Operating Costs ($)
462,000
21,552,000
27,855,000
19,622,000
22,592,000
18,401,000
23,808,000
Total Costs ($)
462,000
40,350,000
50,988,000
46,923,000
61,577,000
49,524,000
57,974,000
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VIII.7.2 Waste Piles
Table 5-42 presents the capital, operating and total costs for each of the Waste rock
Alternatives on the basis of 30-year present worth. Alternative W2 with offsite treat-
ment and landfilling of the waste rock is nearly twice the cost of onsite landfilling of
untreated waste rock. This cost difference is far more significant than the cost differ-
ence noted hereinbefore for the Portal Alternatives. The benefit gained in Alternative
W2 by treatment and offsite landfilling at the price of doubling the total cost, is an
important consideration in selection of a Waste Rock Alternative.
Table 5-42
Summary of Costs
Alternatives
WO No-Action
W2 Waste Pile Removal, Treatment, and Disposal
W3 Consolidating and Capping Waste Piles Onsite
Initial Cost
($)
0
5,918,000
2,810,000
O&M Cost
($/year)
0
0
10,000
30-Year Present
Worth Value ($)
0
5,918,000
2,970,000
VIII.8 Criterion 8-State Acceptance
State acceptance refers to the State's position and key concerns related to the pre-
ferred alternative and other alternatives, and State comments on ARARs or the pro-
posed use of waivers.""
EPA has worked closely throughout the Boulder Creek OU with the California
Department of Toxic Substances Control (DTSC) (the State lead agency), the Regional
Water Quality Control Board (RWQCB), and the Department of Fish and Game. All
three agencies support the selection of EPA's preferred alternative, treatment of the
Richmond and Lawson portal AMD flows.
In a July 20, 1992, letter signed by DTSC and the RWQCB, these two agencies sup-
ported the selection and implementation of treatment as soon as possible. They view
treatment as an interim remedy and encourage the further development and consider-
ation of an alternative that could reduce or eliminate the need for treatment at the site,
including capping, plugging, and resource recovery approaches. These agencies
expressed concerns that designs for the disposal facility for the treatment residuals meet
requirements of the Toxic Pits Control Act and the California Code of Regulations,
Chapter 15. EPA has agreed that the disposal facility must meet these criteria.
The Department of Fish and Game signed a July 20, 1992, letter along with the other
Natural Resource Trustees for the site, supporting the selection of treatment of the
Richmond and Lawson portal AMD flows and cleanup of the seven waste piles. These
agencies recommend that any further follow-up actions to remediate these sources that
might result in some increased risk to the fishery be delayed until such time as the
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current criterical water supply and fishery conditions improve and all other remedial
actions at the site are completed.
VIII.9 Criterion 9-Community Acceptance
This criterion refers to the community's stated preferences through oral and written
comments on EPA's Proposed Plan regarding which components of the alternatives
interested persons in the community support, have reservations about, or oppose.
There was significant community interest in EPA's proposed plan for the Boulder
Creek OU at IMM. EPA's public meeting was attended by over 200 people. EPA
received 19 oral comments at the meeting. EPA received over 100 letters commenting
on the Proposed Plan. In general, the community expressed interest in selecting a
remedy that would safely protect the water and fishery resources, that could be imple-
mented quickly, and that could remediate permanently the long-standing site problems.
Community interest was heightened by the critical water supply and fishery conditions
and the significance of this decision to the overall cleanup strategy for the site.
There was overwhelming support from the community to take immediate action at the
site and overwhelming support to either treat the acid mine drainage discharges, or
take another remedial approach with treatment of the discharges as a component or
contingency action. There was considerable divergence within the community regarding
whether an approach other than EPA's preferred alternative of treatment could or
should be implemented at this time. All commenters supported the use of the inactive
open pit mine, Brick Rat Pit, for sludge disposal.
Approximately 50 letters supported EPA's proposed plan to implement treatment of
the Richmond and Lawson portal AMD discharges with the Simple Mix System
(Alternative Pl-A, FS). They urged EPA to implement the remedy as soon as possible
because of the critical fishery and water supply conditions. They supported treatment
as the only proven and effective alternative available. Many of the letters endorsed the
"interim" nature of the proposed action and EPA's intended efforts to develop and
evaluate a source control approach that could reduce or eliminate the long-term
reliance upon treatment at the site for these sources. Several of the letters urged EPA
to drop consideration of the plug-and-flood alternatives because these alternatives
posed too great a risk to the fishery and water supply and because they are too
speculative. Several letters urged EPA to select the Pl-B treatment alternative, the
High-Density Sludge process, to minimize sludge volumes produced and thus extend the
life of available onsite disposal of sludge in Brick Flat Pit. Some letters encouraged
EPA to select the capping alternative (P6) with the Pl-B treatment option to further
extend disposal capacity.
Approximately 50 letters supported the plug-and-flood alternative proposed by ICI
Americas, Inc., on behalf of Rhone-Poulenc Basic Chemicals, a potentially responsible
party for the site. Many letters cited support for the ICIA approach on the basis that
it could, if successful, provide for a permanent solution to the acid mine drainage
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problem that would not require treatment in the long term. Many felt that it would be
a lower-cost approach. Many commenters supported the ICIA approach on the basis
that a treatment plant would be built as a safeguard and that necessary contingency
measures were integral to the proposal.
Several commenters also supported selecting alternatives that favored approaches that
could benefit the local economy, such as relying on treatment with locally available
neutralizing agents (limestone, fly ash), alternatives that ensure protection of the fishery
and water supply, resource recovery options, and options that could achieve cleanup in
combination with strategies to reopen mining operations at Iron Mountain.
ICIA, on behalf of Rhone-Poulenc Basic Chemicals, submitted detailed comments in
support of their conclusion that P2, the ICIA plug-and-flood alternative, could be safely
implemented, would be effective, and the lowest-cost option.
Responses to the above comments are presented in the attached Responsiveness
Summary.
IX. THE SELECTED REMEDY
EPA is selecting collection and treatment of the Richmond and Lawson acid mine
drainage (AMD) flows. Treatment sludges will be disposed of on-site in the inactive
open pit mine, Brick Rat Pit. EPA also is selecting consolidation and capping of seven
waste piles on-site.
The selected remedy differs in one respect from the preferred alternative in EPA's May
20, 1992 Proposed Plan. EPA is selecting the same technology of the proposed plan,
treatment by chemical neutralization/precipitation, but is selecting the lime/sulfide High
Density Sludge (HDS) process option rather than the Simple Mix System as proposed.
The reasons for selecting the HDS process option are more fully discussed later in this
section.
The major components of the selected remedy include:
• Maintenance of the Richmond and Lawson adits to allow the
mine workings to continue to function as effective collectors of AMD.
• Collection structures, pipelines and equalization to provide for delivery of
all AMD flows collected by the Richmond and Lawson adits to the
treatment facility for treatment.
• Treatment facilities to perform chemical neutralization/precipitation
treatment of the Richmond and Lawson AMD flows. The treatment
shall meet the effluent limitations of 40 C.F.R. §§ 440.102(a) and
440.103(a). Except for pH and TSS levels for discharges into Boulder
Creek or Slickrock Creek, EPA has determined that these standards are
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relevant and appropriate in this application. If the discharge is made to
one of these two creeks it will not be necessary to adjust the pH due to
the expected acidity in the creeks. Treatment for TSS levels would not
be practicable due to the high levels of TSS already in the creeks. If the
discharge is made to Flat Creek, which is not expected to be acidic from
other sources, the pH and TSS standards would be relevant and
appropriate.
EPA has selected treatment alternative Pl-B, the lime/sulfide High
Density Sludge (HDS) process option as the required treatment
technology option. The HDS process option, as discussed in the Boulder
Creek OUFS, relies upon simple mix treatment and equalization for peak
flows beyond the capacity of the HDS plant. The HDS plant shall be
designed to provide capacity to treat sustained elevated flows from the
Richmond and Lawson portals.
• Disposal of treatment residuals on-site in the inactive open pit mine,
Brick Flat Pit. Brick Flat Pit shall be modified to comply with the
applicable requirements of the Toxic Pits Control Act, Health and Safety
Code § 25208, et seq.. and California requirements for disposal of mining
wastes promulgated under Water Code § 13172.
• The seven waste piles (identified as WR-2, WR-12, WR-13, WR-14, WR-
17, WR-18, and WR-19 in the Boulder Creek OUFS) shall be
consolidated on-site and capped in accordance with applicable California
requirements for disposal of mining wastes, promulgated under Water
Code § 13172.
The collection and conveyance systems shall provide for delivery of all base, sustained
and peak AMD discharges from the Richmond and Lawson adits. The treatment plant
shall provide equalization capacity, treatment capacity or combination of both to ensure
that all of the AMD flows are treated in compliance with the performance standards.
The conveyance and treatment facility design shall provide for excess capacity and
redundancy of elements necessary to assure reliability of performance.
The routing of pipelines and siting of tankage and treatment facilities is expected to
have minimal impacts on the undisturbed habitat. The historic mining related
disturbance is significant due to collapse of the underground workings surface mining
and. establishment of roadways on cleared work areas. Pipeline routing and design and
siting of facilities shall minimize impacts on undisturbed habitat by use of existing
cleared work areas and roadways to the maximum extent practicable by avoidance of
siting of any facilities in areas of riparian or wetland habitat. Specifically, Boulder
Creek clean water supplies required for lime slaking shall be drawn from below
Boulder Creek falls for protection of the upgradient wetlands habitat. Any facilities
necessary for collection and conveyance of Lawson portal AMD flows shall be located
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away from riparian habitat and shall provide for protection of the riparian habitat in
areas adjacent to the Lawson Portal.
EPA is selecting the lime/sulfide HDS process option (Pl-B) for the following reasons:
• The lime/sulfide HDS process produces treatment sludges with superior
characteristics with respect to dewatering and teachability. The smaller
volumes of more dense sludge are expected to significantly increase the
life of Brick Flat Pit for use as an on-site sludge disposal facility. The
superior leaching characteristics may allow for reduced regulatory
requirements on the design of the modifications to Brick Flat Pit for
sludge disposal.
• The Simple Mix System relies upon Brick Flat Pit to function as a sludge
dewatering facility as well as a disposal facility. The sludge from an
lime/sulfide HDS plant would be placed in Brick Flat Pit dry. Although
Brick Flat Pit modification designs must address several significant issues
such as storm runoff, the design for placement of HDS sludges is
significantly less complicated and its operation is more within
conventional engineering practice.
• EPA intends to investigate the possibility of siting the HDS treatment
plant downgradient of the Richmond and Lawson portal AMD discharges
during detailed engineering design.
Siting the treatment plant adjacent to Brick Rat Pit, at the top of Iron Mountain, as is
considered in EPA's FS, presents numerous logistical challenges. EPA has concluded
that although these challenges can be met with proper engineering and can assure
reliable operations, alternate siting at a downgradient location could be more easily
engineered to assure reliable operations. The use of the HDS process option may
make this alternative site cost-effective by significantly reducing the volumes of sludge
that must be trucked to Brick Flat Pit for disposal.
More detailed design and cost information will be developed to fully evaluate the
facility siting and reliability issues. The design studies will provide more precise and
detailed costing relative to specific project components regarding siting and reliability.
Many design details will receive further development and evaluation during the design
of the operable unit (e.g., any necessary Brick Flat Pit modifications for sludge disposal
and dewatering operations).
EPA has considered the siting of the HDS treatment plant adjacent to Brick Flat Pit at
the top of Iron Mountain, adjacent to Boulder Creek at the site of the current Boulder
Creek Copper Cementation Plant, and at Minnesota Flats.
For an HDS treatment plant located adjacent to Brick Flat Pit, the treatment plant
could discharge to either Boulder Creek or Slickrock Creek and shall meet the relevant
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and appropriate requirements of 40 CFR § 440.102(a) and § 440.103(a). EPA is not
requiring that the discharge meet the pH or TSS standards of 40 CFR § 440.102(a).
Because these creeks do not meet the ambient water quality criteria pursuant to the
remedial actions being performed in the Boulder Creek OU, EPA is invoking the
ARAR waiver for "interim measures" provide by the NCP at 40 CFR §
300.430(f)(l)(ii)(C)(l). EPA is not requiring that the discharge from the treatment
plant meet ambient water quality criteria in Boulder Creek or Slickrock Creek for this
interim action.
For an HDS process treatment facility located at either the Boulder Creek Copper
Cementation Plant site or at the Minnesota Flats site the treatment plant would
discharge to Boulder Creek and shall meet the requirements of 40 CFR § 440.102(a)
and § 440.103(a), except pH and TSS standards. Because Boulder Creek will not attain
ambient water quality criteria pursuant to remedial actions being performed in the
Boulder Creek OU, EPA is invoking the ARARs waiver for "interim measures"
provided by the NCP at 40 CFR 300.430(f)(l)(ii)(C)(l). EPA is not requiring that the
discharge from the treatment plant meet the ambient water quality criteria in Boulder
Creek for this interim action.
For an HDS treatment facility located at the Boulder Creek site, sludge dewatering
ponds would discharge to Boulder Creek and shall comply with the effluent limitations
of 40 C.F.R. §§ 440.102(a) and 440.103(a), except for the limitation on pH and TSS.
For an HDS treatment facility located at Minnesota Flats additional concerns are
relevant regarding protection of the Flat Creek drainage, including meeting the effluent
limitation for pH and TSS at 40 CFR § 440.102(a). Flat Creek does not currently meet
all ambient water quality criteria (AWQC) and Basin Plan water quality standards due
to a pollution source on Upper Spring Creek, the Stowell Mine. Once this source is
remediated by the RWQCB, EPA expects that Flat Creek could meet AWQCs and
water quality standards. Therefore, discharges from the dewatering of sludge that do
not meet AWQCs must be prevented from entering Flat Creek. Proper design of the
dewatering ponds .may be an economically viable option to either mechanical
dewatering or the Boulder Creek site. More detailed information which will be
developed during design is required to enable making a decision on the suitability of
this site.
For the HDS process option (Pl-B), Brick Flat Pit must be modified to function as a
safe, long-term disposal site for treatment plant sludges. The remedial design of the
disposal facility in Brick Flat Pit shall address and comply with the requirements of the
Toxic Pits Control Act and the California mining waste requirements. The discharge
from Brick Flat Pit shall comply with California mining waste requirements. Because
Boulder Creek and Slickrock Creek do not currently comply with ambient water quality
criteria, and remediation of sources in the interim action pursuant to the Boulder
Greek OU will not allow for compliance with these standards without further actions,
EPA is relying upon a waiver for "interim measures" and is not requiring that the
discharge meet ambient water quality criteria in surface waters receiving the discharge.
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Seven waste piles have been identified for remediation. Available information has
indicated that these largely pyritic waste piles are discharging AMD and/or are actively
eroding into Boulder Creek. The waste piles have not been fully characterized to
assure statistical representativeness of the sampling. However, additional data gathered
during remedial design can be obtained to verify the extent to which the waste piles
should be removed, consolidated and capped. At a minimum, all mining wastes in
these waste piles which qualify as Group A or Group B wastes under 23 C.C.R. §
2571(b) shall be removed for proper disposal.
Some modifications and refinements may be made to the remedy during remedial
design and construction. Such modifications or refinements, in general, would reflect
the results of the engineering design process. Estimated cost for the remedy is $54.0
million. Details of the costs for the treatment component are shown in Table 5-8, PS
and Table 5-9, FS for capital costs and O&M costs. Cost for the waste pile component
of the selected remedy, W-3, is shown in Table 5-42, FS.
Table 5-8
Cost Summary for Alternative PI ($ x 1,000)
Site Preparation
AMD Conveyance System
Treatment Plants
Landfill Construction
Construction Subtotal
Bid Contingencies (10 percent)
Scope Contingencies (30 percent)
General Contingencies (8 percent)
Construction Total
Permitting and Legal (3 percent)
Services During Construction (10 percent)
Total Implementation Cost
Engineering Design Cost (15 percent of construction total)
Total Capital Cost
30- Year Present Worth of O&M Costs, interest equals 5 percent
Total 30-Year Present Worth, interest equals 5 percent
Alternative
Pl-A Simple Mix
1,683
3,623
2,333
2^83
9,922
992
2,977
794
14,685
441
1,469
16^95
2,203
18,798
21,552
40,350
Pl-B HDS
1,683
4,241
4,674
1,614
12^12
1,221
3,663
977
18,073
542
1,807
20,422
2,711
23,133
27,855
50,988
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Table 5-9
Annual Operation and Maintenance Cost Summary of Alternative PI
($ x 1,000)
Site Preparation
AMD and Process Water Conveyance
Treatment Plant
Sludge Landfill at Brick Flat Pit
Total Yearly O&M
Total Present Worth of 30-Year O&M
Simple Mix
62
104
1,186
50
1,402
21,552
HDS
62
112
1,588
50
1,812
27,855
Table 5-42
Summary of Costs
Alternatives
WO No-Action
W2 Waste Pile Removal,
Treatment, and Disposal
W3 Consolidating and
Capping Waste Piles
Onsite
Initial
Cost
$0
$5,918,000
$2,810,000
O&M Cost
($/year)
SO
$0
$10,000
30-Year Present
Worth Value
$0
$5,918,000
$2,970,000
X. STATUTORY DETERMINATIONS
EPA's primary responsibility at Superfund sites is to select remedial actions that are
protective of human health and the environment. CERCLA also requires that the
selected remedial action for the site comply with applicable or relevant and appropriate
environmental standards established under Federal and State environmental laws,
unless a waiver is granted. The selected remedy must also be cost-effective and utilize
permanent treatment technologies or resource recovery technologies to the maximum
extent practicable. The statute also contains a preference for remedies that include
treatment as a principal element. The following sections discuss how the selected
remedy for the Boulder Creek OU at the Iron Mountain Mine site meets that statutory
requirements.
X.1 Protection of Human Health and the Environment
The selected remedy protects human health and the environment from the exposure
pathways that are being addressed in this interim action. The selected remedy
addresses the AMD discharges from the Richmond and Lawson portals and the dis-
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charges from and erosion of seven largely pyritic waste piles. The human health threats
posed by these sources are small and related to direct contact or ingestion of the AMD,
which is unlikely due to the remote location, rugged topography, and restriction on
access to the property. The environmental threats posed by these sources are the very
significant releases of copper, cadmium, zinc, and acidity into surface waters. The
selected remedy will essentially eliminate the discharges from the sources being
addressed in this interim action. The adits and mine workings are very effective
collectors of the AMD, and treatment of the discharges is expected to reduce the
copper, cadmium, and zinc by greater than 99 percent. The consolidation and capping
of the seven waste piles will essentially eliminate the current discharge with proper
remedial design and maintenance.
The Boulder Creek OU provides for an interim action that is not expected to be final
and does not address all of the sources of discharges from the site. The selected
remedy therefore cannot be expected to be fully protective of the environment.
X.2 Compliance with ARARs
The selected remedy for the Boulder Creek OU provides for an interim remedial
action for certain sources at the site. The selected remedy provides for significant
progress towards meeting the objectives of the Superfund cleanup action at Iron
Mountain Mine by providing for large reductions in the discharges of copper, cadmium,
zinc, and acidity from the site. This section discusses the ARARs which the action shall
meet and identifies the ARARs which are being waived.
X.2.1 Portal AMD Discharges
The components of the selected remedy to address portal AMD discharges is collec-
tion, treatment, and disposal of treatment residues onsite. This action shall comply
with the following ARARs in the manner described:
X.2.1.1 Chemical-Specific ARARs - Summary. Chemical-specific ARARs for the
treatment plant include the Clean Water Act effluent Imitations for discharges of mine
drainage from copper mines, exercise of best professional judgment under the Clean
Water Act, Safe Drinking Water Act Maximum Contaminant Levels (MCLs) and non-
zero Maximum Contaminant Level Goals (MCLGs) at the water intake to the City of
Redding, and the Basin Plan water quality objectives.
California law controls the design of units that receive mining waste. Accordingly, the
application of chemical-specific concentrations applicable to sludge disposal is
addressed below in the context of action-specific ARARs, specifically the design, siting,
and closure standards that apply to the disposal unit.
Chemical Specific ARARs - Water Quality in General. A primary adverse
environmental impact from the IMM discharges is on surface waters and the species
which live in those waters. CERCLA provisions respecting water quality criteria and
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the requirements of the Clean Water Act and California Water Code are ARARs for
the Site.
In the final remedy, any discharge from the mine to surface waters should comply with
the water quality objectives in the Central Valley Regional Water Quality Control Basin
Plan. In determining the manner in which the mine discharges should be controlled to
achieve these levels, EPA may use best professional judgment to determine the level of
control. In addition to the use of best professional judgment to achieve the water
quality objectives in the receiving waters, EPA may consider effluent limitations on
related mining activities as potentially relevant and appropriate. Effluent limitations
and best professional judgment are not limitations on the level of control, but simply
represent components in a strategy to achieve the water quality criteria and water
quality objectives.
CERCLA §121(d)(2)(A), 42 U.S.C. §9621(d)(2)(A), states that the remedy selected
must "require a level or standard of control which at least attains—water quality criteria
established under Section 304 or 303 of the Clean Water Act, where such...criteria are
relevant and appropriate under the circumstances of the release or threatened release."
The Act further provides that "[i]n determining whether or not any water quality
criteria under the Clean Water Act is relevant and appropriate under the circumstances
of the release, [EPA] shall consider the designated or potential use of the surface water
or groundwater, the environmental media affected, the purposes for which such criteria
were developed, and the latest information available." (42 U.S.C. §9621(d)(2)(B)(i).)
EPA guidance states that federal water quality criteria for specific pollutants should
generally be identified as ARARs for surface water cleanup if circumstances exist at the
site that water quality criteria were specifically designed to protect, unless the State has
promulgated water quality standards for the specific pollutants and water body at the
site. See "ARARs Q's and A's: Compliance with Federal Water Quality Criteria," Pub.
No. 9234.2-09/FS, June 1990. For most of the hazardous substances released at the
Site, the State has promulgated such water quality standards. Under the CWA, EPA
has developed water quality criteria for the hazardous substances at the Site. Because
the State has adopted specific State water quality objectives for the hazardous
substances at IMM, EPA is selecting the more specific, more stringent State water
quality standards as ARARs. However, as explained in Section X.2.3 below, these
ARARs are being waived for this operable unit
Chemical Specific ARARs - Effluent Limitations. The Clean Water Act regulates,
among other matters, the discharge of pollutants from point sources into navigable
waters of the United States. The discharge of metals-bearing acid mine drainage from
mine adits into Boulder Creek, Spring Creek, and the Sacramento River is the
discharge of pollutants from a point source or sources into navigable waters of the
United States.
Clean Water Act controls are imposed on industries through National Pollutant
Discharge Elimination System ("NPDES") permits, or Waste Discharge Requirements
10011109.RDD 71
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("WDRs") which are permitted on a case by case basis. Because the discharges from
IMM occur onsite, no permit will be required. However, absent an ARARs waiver, the
discharge must meet the substantive requirements of such a discharge permit.
In establishing discharge limits, the permitting agency requires, at a minimum, that the
discharger comply with the effluent limitations established under the Clean Water Act
for the specific industrial category of the discharger. In the event there are no specific
effluent limitations for the type of discharge at issue, the statute provides that the
permit shall contain "such conditions as the Administrator determines are necessary to
cany out the provisions of this chapter." CWA §402(a)(l)(B), 33 U.S.C.
§1342(a)(l)(B). EPA uses "best professional judgement" to establish the effluent
limitations if there is no regulation for the specific discharge category.
There are no technology-based effluent limitations specifically identified for inactive
copper or pyrite mines. There are technology-based limitations for active coal, iron,
copper and zinc mines. Because the problems of acid mine drainage from the
underground mining at IMM are similar to the problems of active open pit and
underground copper mines, EPA has selected the effluent limitations for such copper
mines as relevant and appropriate at the IMM site.
The Clean Water Act's system of technology-based effluent controls establishes effluent
limitations according to whether the discharge is from a new or existing source and
whether the pollutant is conventional, toxic, or a non-conventional, non-toxic pollutant.
Existing sources of toxic discharges were initially required to achieve best practicable
control technology ("BPT1) and then later to achieve best available technology
economically achievable ("BAT").
The BPT and BAT limits on discharges from existing point sources at copper and zinc
mines are the following effluent limitations (40 C.F.R. §§440.102(a) and 440.103(a)):
"The concentration of pollutants discharged in mine drainage from mines that
produce copper [or] zinc...from open-pit or underground operations other than
placer deposits shall not exceed:"
Cadmium - 0.10 mg/1 maximum for any one day
0.05 mg/1 average of daily values/30 consecutive days
Copper - 0.30 mg/1 maximum for any one day
0.15 mg/I average of daily values/30 consecutive days
Lead - 0.6 mg/1 maximum for any one day
0.3 mg/1 average of daily values/30 consecutive days
Zinc - 1.5 mg/1 maximum for any one day
0.75 mg/1 average of daily values/30 consecutive days
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pH - within the range of 6.0 and 9.0 at all times
Total Suspended Solids (TSS) - 30 mg/1 maximum for any one day
20 mg/1 average of daily values for 30 consecutive days
Although potentially relevant and appropriate, the effluent limitations for coal and iron
mines do not provide standards for hazardous substances of concern and employ the
same standard of 6.0 to 9.0 for pH.
At this point in the design, it is possible that the discharge from the treatment plant
could either be into Flat Creek or into Boulder or Slickrock Creeks. It is expected that
the pH of the treatment effluent will be greater than the allowable range so that it
would be necessary to increase the acidity to achieve the 6.0 to 9.0 range. Because
Boulder Creek and Slickrock Creek will continue to have other acid sources, EPA has
concluded that meeting this range would not be relevant and appropriate in these
streams. Flat Creek, however, will not have acidity from other sources so that the pH
of 6.0 to 9.0 will be relevant and appropriate for discharges into Flat Creek.
The treatment plant effluent is expected to contain TSS greater than the allowable
range so that it would be necessary to provide for additional filtration to achieve the
standard. Because Boulder Creek and Slickrock Creek are not likely to achieve this
standard due to the numerous continuing discharges from the site, EPA has concluded
that meeting the TSS standard would not be relevant and appropriate in these streams.
Rat Creek, however, will not have these sources of suspended solids so that the TSS
standard will be relevant and appropriate for discharges into Flat Creek.
Chemical Specific ARARs - Safe Drinking Water Act The Safe Drinking Water Act, 42
U.S.C. §300f, et seq. provides limits on the concentrations of certain hazardous
materials in drinking water "at the tap." CERCLA §121(d)(2)(B) provides that
CERCLA response actions "shall require a level or standard of control which at least
attains Maximum Contaminant Level Goals established under the Safe Drinking Water
Act."
EPA has adopted MCLs or MCLGs for the following hazardous substances:
Substance MCL MCLG
Antimony* 0.006 mg/1 0.006 mg/1
Arsenic 0.050 mg/1 none
Cadmium 0.005 mg/1 0.005 mg/1
Copper
Lead
Mercury 0.002 mg/1 0.002 mg/1
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*
**
***
Silver 0.1 mg/1 (secondary) none
Thallium* 0.002 mg/1 0.0005 mg/1
Zinc 5 mg/1 (secondary) none
Effective January 1994.
Required to employ treatment with an action level of 1.3 mg/1.
Required to employ treatment with an action level of 0.015 mg/1.
These levels are relevant and appropriate with respect to any surface water bodies
which are sources of drinking water. At this time, it appears this description would
only apply to the area of the Sacramento River near Redding's Jewel Creek Intake.
Although this response action is an interim remedial action and does not control all
possible sources which lead to the intake, EPA expects that these standards will be met.
Consequently there is no need to use an interim remedial action waiver for this ARAR.
Basin Plan Standards (Water Quality Objectives). This section discusses the water
quality objectives/standards established by California in the Central Valley Basin Plan.
Section 303 of the Clean Water Act, 33 U.S.C. §1313, provides for promulgation of
water quality standards by the states. The standards consist of designated uses of water
and water quality criteria based on the designated uses (40 C.F.R. §131.3(i)). The
criteria are "elements of State water quality standards, expressed as constituent concen-
trations, levels, or narrative statements, representing a quality of water that supports a
particular use." 40 C.F.R. §131.3(b). The Regional Board has identified these water
quality standards in "The Water Quality Control Plan (Basin Plan) for the Central
Valley Regional Water Quality Control Board (Region 5)" as "water quality objectives."
Table III-l in the Basin Plan identifies water quality objectives for the Sacramento
River and its tributaries above State Highway 32 bridge, an area which includes IMM
and the relevant tributaries as follows:
• Antimony—none
• Arsenic-0.01 mg/1
• Cadmium-0.00022 mg/1
• Copper-0.0056 mg/1
• Lead—none
• Mercury—none
• Silver-0.01 mg/1
• Thallium-none
• Zinc-0.016 mg/1
The Basin Plan states that "The pH shall not be depressed below 6.5 nor raised above
8.5." Basin Plan at III-4.
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The Basin Plan does not differentiate between those tributaries of the Sacramento
River which are above Spring Creek and those water which are unaffected by the
AMD. Accordingly, the water quality objectives apply to all such waters.
The Basin Plan makes several relevant comments regarding water quality objectives.
For example, they do not need to be met at the point of discharge, but at the edge of
the mixing zone if areas of dilution are defined. Basin Plan at III-l. Achievement of
water quality objectives depend on applying them to "controllable water quality factors,"
which are defined as "those actions, conditions, or circumstances resulting from human
activities that may influence the quality of the waters of the State, that are subject to
the authority of the State Board or the Regional Board, and that may be reasonably
controlled." Basin Plan at III-2.
The water quality standards for cadmium, copper, and zinc were established in 1985
and were intended to "fully protect the fishery from acute toxicity since the standards
are based on short term bioassays on the critical life stage of a sensitive species." See
EPA letter of August 7, 1985, from Judith Ayres, Regional Administrator, to Raymond
Stone, Chairman, State Water Resources Control Board, Enclosure 1. As noted above,
these values should vary depending on the hardness of the water. The Regional Board
used a 40 mg/1 water hardness.
On April 11, 1991, the State Water Resources Control Board adopted a California
Inland Surface Waters Plan (91-13). This plan adopted water quality objectives to
protect beneficial uses. The plan specifically retains the site-specific standards for
cadmium, copper, and zinc discussed above.
To the extent practicable in the context of an interim remedial action, discharges
resulting from the treatment plant shall also comply with the following requirements in
the Basin Plan:
Sediment. "The suspended sediment load and suspended sediment discharge
rate of surface waters shall not be altered in such a manner as to cause nuisance
or adversely affect beneficial uses." Basin Plan at III-6.
Toxics. "All waters shall be maintained free of toxic substances in
concentrations that produce detrimental physiological responses in human, plant,
animal, or aquatic life." Basin Plan at III-7.
Guidelines on Mining Waste. The mining guidance, included in the Basin Plan
as Appendix 20, states that "Closure and reclamation plans for all operations will
meet the minimum requirements of regulations in the Surface Mining and
Reclamation Act of 1975 and will be coordinated with the State Board of
Mining and Geology." The Guidance also attaches a diagram of "Best
Management Practices Available for Control of AMD From Abandoned Mines."
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In its letter of March 27, 1992, the Department of Fish and Game has noted that the
State's water rights permits for the Shasta-Trinity unit of the Central Valley Project
should also be considered applicable since these permits define the legally allowable
minimum flows in the Sacramento River. As stated in the letter, "Since the
contamination from this site cannot be totally controlled, streamflow conditions in the
Sacramento River will be the determining factor for evaluating the risk to the health
and environment. At present the only regulation for minimum Sacramento River flows
below Keswick Dam exists in the terms and conditions of these water right permits
pursuant to applicable Water Code sections." Calculations of water quality objectives
must be considered in the context of the flows in the Sacramento River. The water
rights permits define the minimum legally allowed flows.
Although compliance with the Basin Plan water quality objectives are considered
ARARs for the site as a whole, they are being waived for this operable unit. This issue
is discussed in section X.2.3 below.
X.2.1.2 Action-Specific ARARs - Summary. The selected remedy shall address and
comply with all action-specific ARARs as provided herein. Significant action-specific
ARARs include those relating to disposal of the treatment sludge and ARARs directing
activity to protect affected fisheries and habitat.
Selection of this alternative is consistent with statutes such as the Federal and
California Endangered Species Act and the Fish and Wildlife Coordination Acts, since
the remedial alternative is being developed pursuant to a process of consultation like
that required by the Acts. The alternative would also comply with Fish and Game
Code Section 1505, since the improved water quality should result in greater protection
of fishery habitat in the Sacramento River below Keswick Dam.
The disposal unit used for the treatment residue should comply with the applicable
provisions of California Water Code Section 13172 and Health and Safety Code
Section 25208, et seq. (Toxic Pits Control Act of 'TPCA"). The Regional Board mining
waste requirements are ARARs which are applicable to the disposal of the treatment
residue. It is expected that chemical analysis of the treatment residues from the HDS
plant will indicate that the wastes are properly categorized as Group B wastes.
Although the HDS sludge will be less aqueous than the Simple Mix sludge, it may still
contain free liquids subject to TPCA provisions.
Consequently, the unit must not be located in a Holocene fault; shall be located outside
areas of rapid geologic change; shall require flood-plain protection from a 100-year
peak streamflow; shall have liners and a filtrate collection system; shall have pre-
cipitation and drainage controls for a 10-year, 24-hour storm; and shall comply with
specific monitoring requirements.
Insofar as the sludge contains free liquids, the disposal unit must also comply with
TPCA, which prohibits discharge of free liquids into a surface impoundment unless the
surface impoundment does not pollute or threaten to pollute the waters of the State.
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If the treatment sludge contains free liquids, the design of the disposal unit must be
such that the unit does not pose a threat to pollute the waters of the State.
Action Specific ARARs - Sludge Disposal. This section discusses the Federal and State
laws regulating hazardous waste and mining waste. Based upon a consideration of
these laws, EPA has concluded that it is not necessary to use a RCRA landfill for
disposal of the sludge from the treatment plant. The HDS sludge is not a listed waste
under federal law and is not expected to meet any federal characteristic of hazardous
waste. EPA has also concluded that it is not necessary to use a State Hazardous Waste
Control Law landfill for the sludge. Although the sludge will likely exceed some State
characteristics, EPA believes that it would be appropriate to consider the sludge subject
to 22 CCR § 66260.200 and 66260.210, which provide variances for non-RCRA wastes.
After a consideration of the Regional Board requirements for mining related waste, the
probable groundwater quality, the remoteness of the facility location, and the
institutional control of the site as a Superfund site, EPA has concluded that it is
appropriate to employ a variance under State hazardous waste law to use applicable
Toxic Pits Control Act and Regional Board mining waste requirements rather than the
State hazardous waste control requirements for this non-RCRA waste. 22 CCR §
66260.200(f) provides for reclassification of a non-RCRA hazardous waste as non-
hazardous if there are "mitigating physical or chemical characteristics." 22 CCR §
66260.210 provides for a variance from one or more of the requirements of the
Hazardous Waste Control Law if either "[t]he hazardous waste or the hazardous waste
management activity is insignificant or unimportant as a potential hazard to human
health and safety, and the environment" or "[t]he handling, processing, or disposal of
the hazardous waste, or the hazardous waste management activity, is regulated by
another governmental agency in a manner that ensures it will not pose a substantial
present or potential future hazard to human health and the environment." See Health
and Safety Code § 25143(a)(2)(A and B). EPA notes that the Regional Board mining
waste requirements contain adequate environmental safeguards such that the disposal
of the non-RCRA sludge in Brick Rat Pit is "regulated by another governmental agency
in a manner that ensures it will not pose a substantial present or potential future
hazard...." In addition, EPA's oversight of the Site also assures that the activity is
"regulated by another governmental agency."
The sludge is therefore to be regulated under the provisions of Water Code §13172 and
those provisions of the Toxic Pits Control Act which govern mining waste. It is
expected that the mining wastes (including treatment sludge and waste piles) are
classified as Group B wastes.
Note on the Bevill Amendment All of the wastes generated at the Site relate in
some manner to the historic and current mining and mineral processing operations at
the Site and therefore there has been an issue whether these wastes are subject to
federal and State laws governing hazardous waste. As discussed in detail in Appendix
A to the Feasibility Study, both federal and State law exempt certain "Bevill
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amendment" mining wastes from regulation as hazardous waste. Under RCRA
§3001(b)(3)(A)(ii), 42 U.S.C. §6921(b)(3)(A)(ii) (also known as the "Bevill
amendment"), EPA has exempted most mining wastes from regulation as hazardous
waste. Exempted waste are identified in 40 C.F.R. §261.4(b)(7). In the Feasibility
Study, EPA provided an analysis based on an assumption that the Bevill amendment
was a broad exception that applied to all mining wastes. Pursuant to that analysis, the
FS stated that it would be necessary for the mining waste and the sludge to be disposed
of in accordance with applicable provisions of TPCA and the State regulations
governing mining waste. As explained in the Feasibility Study, the State has stated that
it does not believe the AMD is subject to the Bevill amendment.
In a recent District Court opinion regarding the Iron Mountain Mine site, the court
stressed "the limited nature of the Bevill Amendment exclusion" and emphasized that
"(n]ot all mining wastes are excluded by the regulation." This and other language in
the opinion suggests that the court might not consider AMD and the treatment sludge
within the scope of the Bevill amendment, as interpreted under federal law. EPA's
Feasibility Study analysed the design of the treatment sludge landfill as if it were
subject to the Bevill amendment. EPA expects this issue will be revisited in the
litigation. However this issue is ultimately resolved, the Bevill status or not of the
treatment sludge does not affect the design of the landfill since applicable provisions of
TPCA and the State mining waste regulations remain ARARs under this ROD whether
or not the sludge is subject to the Bevill amendment under State or federal law.
Because the treatment sludge will not meet any federal RCRA characteristic, and EPA
is employing a variance under the Health and Safety Code for the disposal of this non-
RCRA waste, the requirements which the disposal location must meet will be the same
whether or not the AMD and the sludge are subject to the Bevill amendment.
Mining wastes .which are within the State's interpretation of Bevill would be subject to
the requirements of the Toxic Pits Control Act (TPCA) and the requirements of Water
Code §13172, detailed in 23 C.CR. §§2571 et seq. See Health and Safety Code
§25143.1(b)(l & 2). EPA considers these provisions ARARs for this response action.
Other State requirements applicable to mining waste are discussed below.
Design and Siting under Water Code Section 13172. Water Code §13172 and
the regulations promulgated thereunder establish three groups of mining waste, Group
A, B and C. It is expected that the mining wastes at the site will qualify as Group B
wastes. These wastes are mining wastes that consist of or contain hazardous wastes,
that qualify for a variance under Title 22, provided that the Regional Board finds that
such mining wastes pose a low risk to water quality; and mining wastes that consist of
or contain nonhazardous soluble pollutants of concentrations which exceed water
quality objectives for, or could cause, degradation of waters of the State. See 23 C.C.R.
§2571(b).
Classification of the mining waste as hazardous under State law is used to determine
which group designation is appropriate for regulation under Regional Board authority.
Under 22 C.C.R. §66261.3, hazardous waste includes wastes which are hazardous under
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federal criteria, as well as wastes which meet criteria established under State law. In
addition to the tests under Federal law, the State identifies as hazardous waste any
waste which exceeds Soluble Threshold Limit Concentrations (STLC) or Total
Threshold Limit Concentrations (TTLC). See 22 C.C.R. §66261.4(a)(2). The
treatment sludge is not expected to exceed federal TCLP levels. Following are the
STLC and TTLC b'mits for hazardous substances at IMM:
Substance STLC (me/n TTLC (me/kg)
Antimony 15 500
Arsenic 5.0 500
Cadmium 1.0 100
Copper 25 2,500
Lead 5.0 1 g/kg
Mercury 0.2 20
Silver 5.0 500
Thallium 7.0 700
Zinc 250 5,000
California also identifies as hazardous those wastes which exceed certain parameters of
toxicity. See 22 C.C.R. §66261.4(a)(3, 4, 5, and 6).
It is necessary to determine which wastes at the Site are hazardous under this State
regulation to determine the group classification of the wastes under Water Code
§13172. At this time, it is expected that any wastes which will be disposed of into new
units would qualify as Group B wastes.
Under State regulations governing the design of mining waste disposal units, the
Regional Board imposes specific requirements on siting, construction, monitoring, and
closure and post-closure maintenance of existing and new units. Group B are subject
to the following restrictions:
• New Group B Units:
Shall not be located on Holocene faults
- Shall be outside areas of rapid geologic change, but may be
located there if containment structures are designed and
constructed to preclude failure
~ Flood protection-protect from 100-year peak streamflow
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Construction standards-far waste piles, the pile must be underlain
with a single clay liner (at least 1 x 10-6 permeability); surface
impoundments and tailings ponds must be underlain with a double
liner, both layers of which have at least 1 x 10-6 permeability); a
blanket-type leachate collection and removal system is required
(the liner and leachate collection and removal system for tailings
ponds must be able to withstand the ultimate weight of the wastes
to be placed there)
Precipitation and drainage controls-one 10-year, 24-hour storm;
precipitation that is not diverted shall be collected and managed
through the required LCRS, unless the collected fluid does not
contain indicator parameters or waste constituents in excess of
applicable water quality standards
- Monitoring-comply with conditions of 23 C.C.R. §§2551-2559
Existing Group B Units:
Flood Protection-protect from 100-year peak streamflow
- Construction standards-same as for new Group B units
Precipitation and drainage controls—one 10-year, 24-hour storm;
precipitation that is not diverted shall be collected and managed
through a required LCRS, unless the collected fluid does not con-
tain indicator parameters or waste constituents in excess of appli-
cable water quality standards
Monitoring-comply with conditions of 23 C.C.R. §§2551-2559
The remedial action shall comply with these requirements and any more detailed
requirements, including specific requirements for installation of clay liners, are
contained in 23 C.C.R. §2572, as necessary in design.
Under 23 C.C.R. §2570(c), Group B wastes may be exempt from liner and leachate
collection and removal systems required if a comprehensive hydrogeologic investigation
demonstrates that natural conditions or containment structures will prevent lateral
hydraulic interconnection with natural geologic materials containing groundwater
suitable for agricultural, domestic, or municipal use and (1) there are only minor
amounts of groundwater underlying the area, or (2) the discharge is in compliance with
the applicable water quality control plan. The unit would remain subject to require-
ments for siting, precipitation and drainage controls, and groundwater, unsaturated
zone and surface water quality monitoring.
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Under 23 C.C.R. §2570, the Regional Board may exempt a mining waste pile from the
liner and LCRS requirement if leachate will not form in or escape the unit.
These requirements should be addressed during design of the units.
Any mining waste units must also comply with the closure requirements for new and
existing mining units under Water Code §13172:
• Group B waste piles-close in accordance with 23 C.C.R. §2581(a), (b),
and (c).
• Group B surface impoundments-close in accordance with 23 C.C.R.
§2582(a) and (b)(l); some surface impoundments with clay liners may
close in place.
• Group B tailings ponds-close in accordance with 23 C.C.R. §2581 (a), (b)
and (c) and 2582(a)
The action shall also comply with State requirements for seismic safety applicable to
construction projects generally (see Department of Fish and Game letter of March 27,
1992), and the Dam Safety Act, in the event of any dam construction or enlargement
(see DTSC and Regional Board letter of March 30, 1992).
Toxic Pits Control Act Under Health and Safety Code §25143.1, Bevill-exempt
wastes are exempt from all provisions of the Health and Safety Code except for the
requirements of the Toxic Pits Control Act (TPCA), Health and Safety Code §25208, et
seq. TPCA prohibits the discharge of liquid hazardous waste or hazardous wastes
containing free liquid into a surface impoundment. See Health and Safety Code
§25208.4(a). If the HDS treatment sludge contains free liquids the disposal facility shall
comply with TPCA requirements, unless the facility is eligible for a variance. Health
and Safety Code §25208.13, provides an exemption for a surface impoundment into
which mining waste is discharged if the discharge is otherwise in compliance with the
requirements for mining waste, and the surface impoundment does not pollute or
threaten to pollute the waters of the state. A hydrogeologic assessment report should
be reviewed if it is determined during design that an exemption is necessary.
Action-Specific ARARs - Protection of Natural Resources. A major concern at IMM is
the impact of the discharges of the acid mine drainage on natural resources. The
Sacramento River, into which the acid mine drainage ultimately discharges, contains a
major fishery. The winter run Chinook, a federally threatened and State-endangered
species, spawn in the waters of the Sacramento River affected by the discharges.
Because of the national significance of these resources, it is particularly important that
EPA assure that any levels of control contained in natural resource protection laws be
considered for the Site.
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The remedial action at IMM should comply with the requirements of the natural
resource protection laws discussed herein. Compliance with the applicable water
quality objectives, which take into account the impacts on aquatic species, should also
meet the substantive requirements of these ARARs to protect the species and their
habitat. EPA is currently complying with the consultation requirements of the
Endangered Species Act.
The federal natural resource ARARs include:
The Endangered Species Act, 16 U.S.C. §1531, et seq.
The Fish and Wildlife Coordination Act, 16 U.S.C. §§661-666
California natural resource ARARs include:
Fish and Game Code § 1505, providing that State agencies are not to conduct
action inconsistent with Department of Fish and Game's efforts to protect
spawning grounds, including "Sacramento River between Keswick and Squaw
Hill Bridge."
Fish and Game Code § 3005 prohibits the taking of any mammal or bird with
poison.
Fish and Game Code §5650 which provides, among other prohibitions that "It is
unlawful to deposit in, permit to pass into, or place into the waters of this
State...substance or material deleterious to fish, plant life, or bird life." EPA's
action is intended to prevent the continuing discharge of acid mine drainage so
that it is no longer deleterious to fish life.
Fish and Game Code §5651 which requires the Department of Fish and Game
to cooperate with the Regional Board to correct "chronic water pollution."
Other requirements are contained in the following provisions of the California Fish and
Game Code:
Fish and
Game
Code Subject
2070 Establishment of lists of endangered species
2080 Prohibition on taking of endangered species
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2090 Issuance of a jeopardy opinion if a project would jeopardize the
continued existence of an endangered species or result in the
destruction or adverse modification of habitat essential to the
continued existence of the species
2091 Specify reasonable and prudent alternatives, subject to the
requirements of Section 2092
2093 Informal consultation
2094 Opportunity for full participation in project consultation
2095 For candidate species
2096 Provides that the article remains in effect until January 1, 1994.
X.2.13 Location-Specific ARAJRs - Summary. The selected remedy shall address and
is expected to comply with all location-specific ARARs. EPA has determined that the
RCRA requirements for management of hazardous wastes, including siting and
construction criteria, are not relevant and appropriate to the management and disposal
of residuals from treatment of the acid mine drainage discharges or the waste piles. As
discussed above, EPA is employing a variance from Hazardous Waste Control Law
requirements for disposal of the non-RCRA waste. Accordingly, the selected remedy
shall comply with requirements of the Toxic Pits Control Act and California
requirements for management and disposal of mining wastes, including siting and
technology requirements for disposal facilities.
The action shall comply with the following location-specific ARARs:
Archeological and Historic Preservation Act. The Archeological and Historic Preser-
vation Act, 16 U.S.C. §469, establishes procedures to provide for preservation of
historical and archeological data which might be destroyed through alteration of terrain
as a result of a Federal construction project or a Federally licensed activity or
program. If any response activities would cause irreparable loss or destruction of
significant scientific, prehistorical, historical, or archeological data, it will be necessary
to follow the procedures in the statute to provide for data recovery and preservation
activities.
National Historic Preservation Act. The National Historic Preservation Act, 16 U.S.C.
§470, requires Federal agencies to take into account the effect of any Federally assisted
undertaking or licensing on any district, site, building, structure, or object that is
included in or eligible for inclusion in the National Register of Historic Places. Criteria
for evaluation are included in 36 C.F.R. § 60.4. Although it does not appear that the
Site is of sufficient historic value to warrant inclusion in the National Register, in the
event that an eligible structure will be adversely affected, the procedures for protection
of historic properties are set forth in Executive Order 11,593 entitled "Protection and
Enhancement of the Cultural Environment" and in 36 C.F.R. Part 800, 36 C.F.R. Part
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63, and 40 C.F.R. §6.301(c). These procedures are relevant and appropriate for any
action that might impact historic properties. At this time, it does not appear that any
of the remedial alternatives under consideration would have any adverse impacts on
historic structures.
Clean Water Act (Section 404). Section 404 of the Clean Water Act, 33 U.S.C. §1344,
requires a permit for discharge of dredged or fill material into navigable waters.
Section 502(7) of the Act defines "navigable waters" as "waters of the United States
including the territorial seas." Boulder Creek and the Sacramento River are 'Waters of
the United States." Components of the selected remedy, including removal of tailings,
the surface-water diversions, road construction, and capping, are likely to affect Boulder
Creek.
Selection of a CERCLA remedy falls within the definition of activities covered by the
"nationwide permits" regulations. Under 33 C.F.R. §330.5, specified activities are per-
mitted, provided that certain conditions are met. This provision covers "[structures,
work, and discharges for the containment and cleanup of oil and hazardous substances
which are subject to the National Oil and Hazardous Substances Pollution Contingency
Plan (40 CF.R. Part 300)...." (33 C.F.R. §330.5(a)(20).) Under 33 C.F.R.
§330.5(a)(20), a nationwide permit is available only if "the Regional Response Team
which is activated under the [National Contingency] Plan concurs with the proposed
containment and cleanup action." Substantive requirements are potentially applicable,
including the substantive conditions set forth in 33 C.F.R. Section 330.5 (b), the
management practices outlined in 33 C.F.R. Section 330.6, and the requirements
governing road construction activities in 33 C.F.R. Section 323.4(a)(6).
Executive Order on Floodplain Management The action shall comply with the
Executive Order on Floodplain Management, Executive Order No. 11,988, which
requires Federal agencies to evaluate the potential effects of actions that may take
place in a floodplain to avoid, to the extent possible, adverse effects associated with
direct and indirect development of a floodplain. EPA's regulations to implement this
Executive Order are set forth in 40 C.F.R. §6.302(b) and Appendix A. In addition,
EPA has developed guidance entitled "Policy on Floodplains and Wetlands Assessments
for CERCLA Actions," dated August 6,1985. Some of the proposed remedial activities
could affect the 100-year floodplain of Boulder Creek.
Executive Order on Protection of Wetlands. The remedial action shall comply with the
Executive Order on Protection of Wetlands, Executive Order No. 11,990, which
requires Federal agencies to avoid, to the extent possible, the adverse impacts
associated with the destruction or loss of wetlands and to avoid support of new
construction in wetlands if a practicable alternative exists. EPA's regulations to
implement this Executive Order are set forth in 40 C.F.R. §6.302(a) and Appendix A.
In addition, EPA has developed guidance entitled "Policy on Floodplains and Wetlands
Assessments for CERCLA Actions," dated August 6, 1985.
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A botanical survey in the Boulder Creek drainage at Iron Mountain Mine stated that
"the ecological and environmental devastation to Boulder Creek below the Hornet
Mine is so great that little time is needed to understand the problems and determine
that in most of Boulder Creek much of the original flora is gone." The September 14,
1992 memorandum from Richard Lis and Harry Rectenwald of the California
Department of Fish and Game documenting this survey concludes that the construction
activities related to the proposed remedial action "would not result in any significant
decrease in the existing riparian or wetland habitat. Instead it may actually increase the
total riparian habitat along the creek. This increase would be significant because it
would be within the most biologically healthy reach of the creek."
5L2.2 Waste Piles
The component of the selected remedy that addresses the AMD discharges from and
erosion of waste piles to surface waters is expected to comply with the following
ARARs:
X.2.2.1 Chemical-Specific ARARs. California law controls the design of units that
receive mining waste. Accordingly, the application of chemical-specific concentrations
applicable to sludge disposal is addressed below in the context of action-specific
ARARs, specifically the design, siting, and closure standards that apply to the disposal
unit.
As a portion of the Boulder Creek Operable Unit, the remediation of the waste piles
will contribute to compliance with the chemical-specific ARARs discussed above for the
treatment of AMD, including the Safe Drinking Water Act, and the Regional Board
Basin Plan standards. As discussed above, however, it will be necessary to implement
further response actions before full compliance with the Basin Plan standards can be
achieved.
X.2.2.2 Action-Specific ARARs. The selected remedy shall address and comply with all
action-specific ARARs identified in Appendix A to the Feasibility Study. Significant
action-specific ARARs include those relating to disposal of the waste piles and ARARs
directing activity to protect affected fisheries and habitat.
Selection of this alternative is consistent with statutes such as the Federal and
California Endangered Species Act and the Fish and Wildlife Coordination Acts, since
the remedial alternative is being developed pursuant to a process of consultation like
that required by the Acts. The alternative would also comply with Fish and Game
Code Section 1505, since the improved water quality should result in greater protection
of fishery habitat in the Sacramento River below Keswick Dam.
The disposal unit used for the waste piles should comply with the provisions of
California Water Code Section 13172 and Health and Safety Code Section 25208,
et seq. (Toxic Pits Control Act of 'TPCA"). These ARARs are applicable to the
disposal of the treatment residue. It is expected that chemical analysis of the treatment
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residues will indicate that the wastes are properly categorized as Group B wastes. The
requirements for disposal of Group B wastes are discussed in greater detail above in
connection with disposal of the treatment sludge.
Consequently, the unit must not be located in a Holocene fault; shall be located outside
areas of rapid geologic change; shall require flood-plain protection from a 100-year
peak streamflow; shall have liners and a filtrate collection system; shall have pre-
cipitation and drainage controls for a 10-year, 24-hour storm; and shall comply with
specific monitoring requirements.
The disposal unit must also comply with TPCA, which prohibits discharge of free liq-
uids into a surface impoundment unless the surface impoundment does not pollute or
threaten to pollute the waters of the State. Because the waste piles contain free
liquids, the design of the disposal unit must be such that the unit does not pose a threat
to pollute the waters of the State.
X.2.2J3 Location-Specific ARARs. The selected remedy shall address and is expected
to comply with all location-specific ARARs discussed above.
X.2.3 ARAR Waivers For this Operable Unit
This section summarizes which ARARs are subject to ARAR waivers. Because the
Boulder Creek Operable Unit is an interim remedy, it can qualify for the ARAR waiver
for such actions. CERCLA §121(d)(4)(A), 42 U.S.C. §9621(d)(4)(A), provides that
ARARs may be waived if "the remedial action selected is only part of a total remedial
action that will attain such level or standards of control when completed."
The ARARs which are being waived for purposes of this operable unit are:
The Basin Plan water quality objectives, discussed in detail below. Because the
treatment plant does not address all sources which are contributing to the
exceedances of the water quality objectives, it is not possible to fully comply with
ARARs until further response actions are selected and implemented.
Fish and Game Code Section 5650, which prohibits "permitting] to pass
into ... the waters of this State ... substance or material deleterious to fish,
plant life, or bird life." Because the treatment plant would not address all
sources at this site, this alternative would not eliminate all releases. It would,
however, eliminate 99 percent of the material passing into the waters from the
two portal sources.
The overall remedy, including the activities in the 1986 Record of Decision, this
Operable Unit and subsequent operable units are expected to achieve compliance with
these ARARs (at least in those portions of the Site immediately below Keswick Dam).
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EPA has previously stated that the Boulder Creek Operable Unit will be followed by
other studies and remedial actions to address matters such as releases from Old
Mine/No. 8 and the sediments in the Spring Creek Arm of Keswick Reservoir. Those
activities are not a part of this OU. The Boulder Creek Operable Unit, however, is not
expected to achieve this ARAR in all years without the planned further remedial
action. As such, the Boulder Creek Operable Unit is an interim remedy. In the event
of an interim remedy, EPA may elect to invoke an interim remedial action waiver as
provided in CERCLA §121(d)(4)(A), 42 U.S.C. §9621(d)(4)(A).
There is also some question regarding the technical practicability of meeting water
quality objectives in certain segments of Boulder Creek. In particular, it may not be
technically practicable to meet the water quality objectives in certain portions of
Boulder Creek. In such a case, EPA may consider the use of a waiver under CERCLA
§121(d)(4)(C), 42 U.S.C. §9621(d)(4)(C). The preamble to the NCP discusses the use
of the technical impracticability waiver at 55 Fed. Reg. 8748 (March 8, 1990). The
main criteria for invoking this ARAR waiver are engineering feasibility and reliability.
EPA explained in the preamble that cost plays a "subordinate role" in determining
whether a remedial action is "practicable from an engineering perspective." Id.
Because this action is an interim remedial action, EPA is not today reaching any
conclusions regarding the technical impractacability of achieving ARAR compliance in
Boulder Creek, but is invoking the interim remedy waiver for all stream segments.
The selected remedy will not provide for compliance with the applicable chemical-
specific ARARs of the Central Valley Regional Water Quality Control Basin Plan
water-quality objectives, as discussed below. The selected remedy will allow for
compliance with these water quality objectives most of the time and represents a
significant improvement compared to the No-Action Alternative, PO. The selected
remedy will not provide for meeting water quality objectives in Boulder Creek.
Subsequent remedial measures will address other sources of contamination that prevent
achievement of the water quality objectives in the Sacramento River. A subsequent
study will also address whether or not a waiver for technological impracticability is
appropriate for water quality objectives in the Boulder Creek watershed.
X3 Cost-Effectiveness
EPA has concluded that the selected remedy is cost-effective in mitigating the risk
posed by the discharge of heavy metal-laden AMD from the Richmond and Lawson
portals and waste piles to surface waters. Section 300.430(f)(ii)(D) of the NCP requires
EPA to evaluate cost-effectiveness by comparing all the alternatives against three
additional balancing criteria: long-term effectiveness and permanence; reduction of
toxicity, mobility, or volume through treatment; and short-term effectiveness. The
selected remedy meets these criteria and provides for effectiveness in proportion to -its
cost. The estimated cost for the HDS treatment component is $51.0 million. The
estimated cost of the waste pile component is approximately $3.0 million. The total
cost of the selected remedy is $54.0 million.
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X.4 Utilization of Permanent Solutions and Alternative Technologies or Resource
Recovery Technologies to the Maximum Extent Practicable
EPA has determined that the selected remedy represents the maximum extent to which
permanent solutions and treatment technologies can be utilized in a cost-effective
manner for the interim remedial action for the Boulder Creek OU at Iron Mountain
Mine.
EPA recognizes that the mineralization at Iron Mountain Mine will continue to gener-
ate acid mine drainage unless additional remedial actions are developed, evaluated, and
selected for implementation to reduce or eliminate the AMD-forming reactions.
Treatment does not address the reactions themselves. Treatment effectively addresses
the resultant discharges. EPA has developed and evaluated alternatives as part of the
Boulder Creek OU that could reduce or eliminate the AMD-forming reactions.
Resource recovery alternatives have been proposed and evaluated. EPA has concluded
that further information is required to be developed and evaluated before one of these
approaches could be selected for implementation. The needed further information
would address technical feasibility, implementability, effectiveness, and cost-
effectiveness concerns and risk factors with respect to these approaches. EPA
encourages the further development of source control alternatives and resource recov-
ery alternatives for future evaluation and potential selection in a subsequent action.
The selected remedy will provide for a significant reduction in the copper, cadmium,
zinc, and acidity discharges from the site. The current water supply and fishery condi-
tions are critical. There is a critical need to implement controls on these discharges as
soon as possible, while studies are ongoing with respect to further source control or
resource recovery approaches. Treatment is effective, a part of each approach devel-
oped to date, and is consistent with implementation of a subsequent action.
X.4.1 Preference for Treatment as a Principal Element
Although EPA is not selecting a remedy which treats the source such that no further
AMD is formed, EPA is using treatment to reduce the toxicity and mobility of the
AMD which is being generated. By selecting lime/sulfide HDS instead of Simple Mix,
the treatment will also reduce the expected volume of the sludge. HDS sludge will also
be less toxic than the Simple Mix sludge.
Mine sealing or plugging alternatives present the potential to completely stop the
AMD-forming reactions and the discharge if the surrounding rock mass can contain a
mine pool at elevations sufficient to inundate all mineralization. The plugging alter-
natives might (with innovative approaches) address acidic metal-laden salts that dissolve
in the flooding mine pool, and thus, are mobilized and create a discharge pathway
through fractures or mining-related openings. A partially successful plugging alternative
would reduce the AMD-forming reactions, but not eliminate them. A partially
successful program presents risks of release of contaminants to the environment.
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Other alternatives such as intercepting groundwater flow and capping areas which
channel infiltrating water towards mineralization would likely reduce the rate of reac-
tion of the AMD formation, but not eliminate them. These alternatives provide less
risk of creating new discharge pathways and rely on conventional engineering
approaches.
Resource recovery approaches merely treat the discharge recovering economic values.
Conventional treatment is effective at eliminating the discharge, but does not treat the
sources of the discharge.
EPA encourages the continued development and evaluation of alternatives that may
partially satisfy the preference for treatment as a principal element, and this issue will
be addressed in the final decision document for the site. EPA has concluded that
further development and evaluation of the above approaches is necessary to address
uncertainties with respect to technical feasibility, implementability, effectiveness, cost-
effectiveness concerns, and risk factors.
XI. DOCUMENTATION OF SIGNIFICANT CHANGES
EPA is today approving the proposed plan with one change. That change involves the
use of a more reliable and more effective treatment method than was used in the
proposed plan. In all other respects, including the use of Brick Flat Pit as the sludge
disposal location, this action is consistent with the proposal.
In the proposed plan dated May 20,1992, EPA identified its preferred plan for cleanup
of Boulder Creek contaminant sources as "collecting the acid mine drainage (AMD)
discharges from the Richmond and Lawson tunnels and treating them at a lime
neutralization plant. The treated water would be discharged into Slickrock or Boulder
Creeks and the treatment plant sludge, containing the removed heavy metals, would be
disposed of in the open pit mine on-site." As stated in the fuller discussion of
Alternative PI, two treatment processes could be used, either PI A, the simple mix
system, or P1B, the High Density Sludge option. EPA stated that its preferred
alternative was PI A. Among other criteria, EPA indicated that it believed PI A was the
lowest cost alternative.
Today's action selects treatment as proposed with one difference. Based upon a
consideration of the public comments, EPA is today selecting use of a treatment system
which relies principally upon the High Density Sludge method rather than the originally
preferred Simple Mix System. Under the lime/sulfide HDS method selected, HDS
would be the principal treatment method, but Simple Mix would be used as a back-up
system for emergencies.
A major concern raised in public comment was the limited sludge disposal capacity
using simple mix. In public comment, many persons noted that the disposal capacity of
Brick Flat Pit was limited to only 60 to 150 years using the Simple Mix System, but as
discussed above, the sludge capacity for HDS is much greater, conservatively estimated
10011109.RDD
89
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at 120 to 250 years. Even though EPA believes treatment is only an interim remedy, it
is possible that sludge disposal capacity could become increasingly of concern in the
next century, depending upon what other remedial actions are ultimately selected.
Use of lime/sulfide HDS rather than Simple Mix would also prolong the use of Brick
Flat Pit for sludge disposal in the event one of the other alternatives, such as plugging,
is later selected, since these alternatives would also require some treatment.
Use of lime/sulfide HDS instead of Simple Mix should also help address concerns
regarding the toxicity of the sludge. Some persons submitting comments were
concerned regarding the disposal of toxic metals, even if treated, back on the site and
expressed concerns regarding the ability of the treated sludge to re-enter the
environment. EPA's tests on treated sludge have shown that HDS is more effective in
binding the metals in the sludge than is Simple Mix. These tests have shown that it is
more probable that the treated sludge will not qualify as "hazardous" under federal
characteristics after treatment with HDS, than is the case with simple mix.
An overwhelming number of comments called for the immediate implementation of an
effective, reliable system. Use of HDS rather than Simple Mix is also responsive to
these concerns. In response to these comments, EPA closely considered the relative
effectiveness of Simple Mix and HDS, and has concluded that HDS may be a more
reliable system.
10011109.RDD
90
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SEr-j>e5-i552
IU
5141^7442 leva
STATE Of
CS A(VMCT
PETE WILSON.
(DEPARTMENT OF FISH AND GAME
1416 NINTH STREET
P.O. BOX 944209
SACRAMENTO. CA 94244-2090
(916)
September 30, 1992
Mr. Jeffery Zelikson, Director
Hazardous Waste Management Division
U.S. Environmental Protection Agency
Mail Code Hi
75 iiawtnorne Boulevard
San Francisco, California 94105
Dear Mr. seliKson:
The Department of Fish and Game has reviewed the draft
Rec'ord of Decision Tor the Iron Mountain Mine Supcrfund Site.
This site has a long history of damaging some of the State's most
important fishery and water resources. The chinook salmon
spawning area in the upper Sacramento River (above the confluence
with the Feather River) currently supports the most valuable
salmon fishery in the State. The Iron Mountain Mine Superfund
Site impacts the most valuable portion of this saltnon spawning
area as well as other important biological resources.
We support the decision to install a proven treatment
technology on the portal effluent without flooding the mine pool
and the cleanup of selected pyrite bearing waste piles. We
believe that it is important to avoid flooding the mine pool when
the water and fishery resources are in such critically poor
condition and other remedial actions require completion. The
performance of the plug and Hood alternative is uncertain and
there is a risk that the mine pool fluids will leak out where
they cannot be immediately collected and treated.
: In the future the treatment remedy may be replaced by
another source control technology or a resource recovery action.
we i understand that the Environmental Protection Agency (EPA) will
evaluate alternative replacement technologies using a new
feasibility study and record of decision process along witn
endangered species consultation. Prior to implementing
replacement remedies that have higher risk, we recommend EPA
consider not replacing proven technologies w^thc^|her_""_ ir
alternatives until the drought conditions end Shasta ^servoir
Storage returns to normal, declines of the salmon stock s ar e
reversed, salmon fishery restrictions return to jo™1 «£
other necessary remedial actions are completed at the site.
1 We would like to thank you for selecting a
for this complex site. We look forword to
staff on the remaining necessary remedial
at the site,
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:==.(— .-.iiJ-lSai tto'eiY
Mr. Jeffery Zelikson
September 30, iyy
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DEPARTMENT OF TOXIC SUBSTANCES CONTROL
10161 CROYOON WAY. SUITE 3
'•&CRAMENTO. CA 96827-2106
September 30, 1992
Mr. David B. Jones
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94105
IRON MOUNTAIN MINE SUPERFUND SITE, COMMENTS ON DRAFT RECORD OF
DECISION
Dear Mr. Jones:
Thank you for providing us with a copy of the Draft Record
of Decision ("DROD") for the Boulder Creek Operable Unit of the
Iron Mountain Mine Super fund Site.
After our review of the document and telephone
communications between the Department of Toxic Substances Control
(DTSC) and the U.S. Environmental Protection Agency (EPA) staff,
we understand that the ROD will reflect the following:
1. The State does not consider AMD to be exempt from the
California Hazardous Waste Control Laws, Chapter 6.5,
California Health and Safety Code section 25100 et. seq.
The State acknowledges that treatment of AMD and disposal of
the resultant sludge may be subject to a variance pursuant
to California Health and safety Code Section 25143.
2. The scope of the expected "final" remedial alternatives for
the Boulder Creek operable Unit will be based upon further
investigations of waste rock piles, creek sediments, seeps
and the feasibility of source control or resource recovery
at the Richmond Mine workings.
3. The proposed CERCLA Section 121 (d) (4) (A) Waiver of
Compliance with the Regional Boards's Basin Plan Water
Quality Objectives will not be invoked for discharges to
Flat Creek.
Based on the above modifications of the DROD, we conclude
that the DROD is acceptable. We look forward to working together
with EPA in the development of the remedial design parameters for
the Boulder Creek Operable Unit, and the implementation of future
actions at the site.
2 'd L0-f\ 26/52/60 WOMd
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Mr. David B. Jones
30« 1992
If you have any questions concerning this letter or if we
can assist you in any way, please contact Duncan Austin at
(916) 855-7861.
Sincerely,
Anthony J. Landis, P.E., Chief Janes C. Pedri, P.E.
Site Mitigation Branch Supervising Engineer.
Department of Toxic Substances Regional Water Quality Control
Control Board
cc: Mr. Rick Sugarek
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94105
Mr. Ramon Perez
Department of Toxic substances Control
P.O. Box 806
Sacramento, California 95812-0806
Mr. Gary Stacey
California Department of Fish and Game
601 Locust Street
Redding/ California 96001
Ms. Lisa Trankley-Sato
Department of Justice
1515 K Street, Suite 260
Sacramento, California 95814
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IN REPLY REFER TO.
United States Department of the Interior
OFFICE OF THE SECRETARY
Office of Environmental Affairs
600 Harrison Street, Suite 515
San Francisco, California 94107-1376
TAKE
September 30, 1992
Mr. Rick Sugarek
U.S. EPA - Region IX
75 Hawthorne Street - H-6-2
San Francisco, CA 94105
Dear Mr. Sugarek,
We are writing as natural resource trustees concerning two issues
involving Iron Mountain Mine, Shasta County, California. First,
with regard to the draft Record of Decision, as we noted in our
comments on the draft plan, we agree with the selection of
treatment for an interim remedial action. By selection of
alternative Pl-B, the High Density Sludge Process, EPA is selecting
an alternative to produce maximum reduction of waste volume. If
the HDS plant is designed to provide capacity to treat sustained
elevated flows, concerns regarding the ability of the selected
alternative to respond to emergency high flow levels are met.
Secondly, we are aware that ICI Americas has indicated by letter
that they believe that Judge Schwartz's September 21, 1992 ruling
in United States of America v. Iron Mountain Mines. Inc.. et al.
makes EPA Administrative Order No. 92-96 invalid. Naturally, we
are concerned, as the sixth year of drought has made this a
critical year for survival of the Federally threatened winter-run
Chinook salmon. As the species may not survive the impact of
untreated discharge through the season, we are supportive of EPA's
intent to implement the requirements of the administrative orders
utilizing Superfund, with cost recovery later.
If you wish to meet with the natural resource trustees for Iron
Mountain Mine concerning our comments, please contact me at (415)
744-4090.
Sincerel
William C. Allan
Regional Environmental Assistant
Concur:
Denise Klimas
National Oceanic and Atmospheric Administration
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