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\_- - -. -- ---
United Slates
Environmental Protection
Agency .
Office of
Emergency and
Remedial Response
EPAIROD/R08-881020
March 1988
aEPA
Superfund
Record of Decision:
~g~1-/53 7/2-
(;1
)J
CaJifomia Gulch, CO
U.S, Envirtjfjffj9f1tal p. ;
R@gig/J IlZ tIIlo/mati faieci/on AgenCI
C~fitQf (3PM52) on Resour~
~41 Chestnut Street 7' . .-":
~hIlQd~lphia, PA 191n'J ",,,',:!.::;~~W
W( .~..~~~~~
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.
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50272 . UI1
REPORT DOCUMENTATION 11. REPORT NOEP A/ROD/RO 8 -8 8/ 020
PAGE
4. Title and Subtitle
SUPERFUND RECORD OF DECISION
~~lifornia Gulch, CO
.rst Remedial Action
I-
7. Author(s)
9. Performln. O,.anlutlon Name and Addres.
o
12. Sponsorln. 0188nlzatlon Name and Addre..
U.S. Environmental protection
401 M Street, S.W.
Washington, D.C. 20460
Agency
15. Supplementary Not..
z.
3. Recipient'. Acc...lon No.
5. Re~~/88
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6.
8. Performin8 O...aniution Rept. NO.- - -
10. Project/T..k/Work Unit No.
-- --
----
11. Contract(C) or Grant(G) No.
(C)
(G)
--
13. Type 0' Report 6 Period Covered
800/000
14.
1.. AbstF8Ct (Umlt: 200 _rdl)
The California Gulch site is located in Lake County, Colorado, approximately
100 miles southwest of Denver. The study area for this first remedial action
encompasses an 11.5 m2 watershed, which includes the city of Leadville, that drains
along California Gulch to the Arkansas River. Between 1859 and 1986, the area was
extensively mi~ed for gold, lead, silver, copper, zinc and manganese. Because of ~hese
~ining operations, the Yak Tunnel was constructed to dewater mines and facilitate
ineral exploration and development. Studies indicate that the Yak Tunnel discharges a
combined total of 210 tons per year of cadmium, lead, copper, manganese, iron, and zinc
into California Gulch, which drains into the Arkansas River. Both California Gulch and
the Arkansas River are used by the public for recreation, and the Arkansas River is
heavily used for irrigation, livestock watering, public water supply and fisheries as
well. Surface water contamination is the majbr impact of the Yak Tunnel discharge.
Heavy metal migration through surface water has also caused ground water and sediment
contamination. primary contaminants of concern affecting the surface water, sediments,
and ground water are cadmium, copper, lead and zinc.
(See Attached Sheet)
17. Document Analysl. a. Dncriptors
Record of Decision
California Gulch, CO
First Remedial Action
Contaminated Media: gw, sw, sediments
Kev Contaminants: ~admium, copper, lead,
-b. 1dentlfle.../Open.Ended Terms
c. COSATI Field/Group
,allabllity Statement
(S.. ANSI-Z39.18)
zinc
"--.
19. Security Class (This Report)
None
21. No. of Pa8es
171
-
--
20. Security Class (This Pa.e)
None
22. Price
s.. InstructIons on A.".,..
OPTIONAL FORM 272 (4-77)
(Formerly NTI~35)
Department of Commerce
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A/ROD!R08-88/020
vdlifornia Gulch, CO
First Remedial Action
16.
ABSTRACT (continued)
u
~
The selected remedial action for this site includes: construction of surge ponds at
the portal of Yak Tunnel to protect the California Gulch site and the Arkansas River
from accidental release of acid water, sludge, and sediments; construction of concrete
plugs at locations in the tunnel to reduce migration of contaminated water and reduce
the extraction of metals from raw mineral ore; sealing shafts and drill holes, diversion
of surface water away from tunnel recharge areas, and grouting of highly fractured rock;
implementation of a monitoring program to detect leaks, seeps or migration of
contaminated ground water; and installation of an interim treatment plant to treat
ground water, which will be pumped to control surface seeps and migration of
contaminated surface water. The estimated capital cost of the selected remedy i~
'11,982,770 with annual O&M costs of '460,307.
.
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ft
o
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
RE GION VID
999 18th STREET - SUITE 500
DENVER. COLORADO 80202-2405
u
DECLARATION
FOR THE
RECORD OF DECISION
SITE NAME AND LOCATION
California Gulch
Leadville, Lake County, Colorado
Operable Unit I -- Yak Tunnel
STATEMENT OF BASIS AND PURPOSE
. . ,
This decision document presents the remedial act10n for
operabie Unit I of the California Gulch site selected by the
United States Environmental ~rotection Agency (EPA) in accordance
with the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (CERCLA), as amended by the Superfund
Amendments and Reauthorization Act of 1986 (SARA), and the
National Contingency Plan (NCP).
~/
This decision is based upon the administrative record for
the Yak Tunnel operable unit of the California Gulch site. The
. attached index identifies the items which comprise the
administrative record upon which the selection of the remedial
action was based. .
The State of Colorado has reviewed the selected remedy.
DESCRIPTION OF THE SELECTED REMEDY
Operable Unit I addresses the discharge of acid mine
drainage containing high levels of metals from the Yak Tunnel
into California Gulch. The hazardous substances of primary
concern are cadmium, copper, lead, and zinc. The Yak Tunnel
discharge contributes to contamination of California Gulch, the.
Arkansas River, and the associated shallow alluvial ground water
and sediment systems. .
The selected remedy for this operable unit of the California
Gulch site is designed to minimize the flow of water out of the
Yak Tunnel and to prevent the uncontrolled release of tunnel
effluent to the environment. The remedy,ls comprised of the
following elements.
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1. Measures to minimize the impact of surqes from the
tunnel on California Gulch and the Arkansas River.
Surge ponds will be constructed at the portal of the Yak
Tunnel to protect California Gulch and the Arkansas River from
accidental releases of acidic water, sludges, or sediments from
the tunnel due to tunnel inspections or construction. Surge
ponds will be constructed prior to the installation of the tunnel
plugs. Once the plugs are in place, the surge ponds will be
incorporated into the interim water treatment system described
below.
.
2. Construction of concrete pluqs at three locations within
the tunnel to flood the sulfide zones, to halt the
uncontrolled discharge of tunnel effluent to California
Gulch, and to prevent surqes.
Plugs will be located in competent rock n~ar the tunnel
portal, in the Ibex-Irene area near the middle of the tunnel, and
below the Resurrection Mine workings near the head of the tunnel.
The plugs will serve two primary functions: source cont~ol and
management of migration. Water will rise and flood the void
space behind each of the plugs. To the extent that sulfide
mineral zones exist in these areas, they will be totally or
partially inundated. Such inundation will prevent or reduce the
chemical reactions which release metals from the minerals,
thereby reducing the contamination of water within the
mineralized zones. In addition, the plug~ will minimize the
migration of contaminated water to California Gulch. The plugs,.
especially the lowermost one, will serve to prevent surges of
water, sludges, and sediments from the portal of the tunnel.
3. Measures to minimize the inflow of surface water and
ground water into the Yak Tunnel System.
These measures include sealing shafts and drill holes,
diverting surface water away from tunnel recharge areas, and
grouting areas of h~ghly fractured rock. This combination of
measures will reduce the amount of water entering the Yak Tunnel
system and will thereby decrease the cost and enhance the
effectiveness of the related response actions.
4. Implementation of a monitoring program to detect any
leakage, seeps, or migration of contaminated ground water.
Evaluation and modeling of all available geological and
hydrological information indicates that rising water levels in
the mine voids behind the plugs may result in surface seeps,
particularly in the area behind the portal plug. Also, there is
the potential for contaminated ground water to migrate towards
areas where it may have a negative impact, such as Evans Gulch or
the vicinity of the Leadville Drainage Tunnel. For these
2
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reasons, a monitoring network will be constructed prior to the
installation of the tunnel plugs.
Ii
The monitoring program will consist of both field inspection
and a surface and ground water monitoring network. Periodic
field inspections will be needed to identify any surface seepage,
particularly in the vicinity of the portal plug. The ground
water monitoring network will consist of a series of monitoring
wells and/or shafts to measure water levels and water quality.
The number and location of monitoring points associated with each
plug will depend on the geologic and hydrologic conditions
associated with each. The monitoring points will be used to
identify baseline information on ground water levels and quality,
against which changes in water levels and quality can be
measured. The surface water monitoring network will be used to
monitor changes in both quality qr flow as a result of the
remedy. Surface monitoring stations will be in California Gulch
and Evans Gulch. Both the field inspections arid the periodic
water measurements will be used to predict, identify, and track
any surface water seeps or changes in ground water flow and
quality. ,
S. Measures to prevent uncontrolled miqration of
contaminated water.
Because rising water levels pose a risk of seepage and
migration of contaminated water, the selected remedy incorporates
measures to mitig~te this risk. Grouting of potential leakage
points, such as fracture zones, caved-in areas, and drill holes,
will be done. To control ground water levels, and thereby
control surface seeps and migration of contaminated water, a
system to lower water levels will be installed behind the portal
plug. As necessary, water will be pumped from behind the portal
plug and routed to an interim treatment plant near the portal of
the tunnel. The plant will use available technologies to settle
out metals and then release the water to California Gulch. The
surge ponds described above will become part of this treatment
system. Sludge will be retained in the ponds while the interim
treatment system is operating. As part of a subsequent operable
unit, a comprehensive treatment system will be developed and
integrated into a permanent site remedy. .
. The selected remedy also includes contingency plans for the
Ibex-Irene and Resurrection plugs. Because the probability of
surface seepage caused by these plugs is small, at the outset
only monitoring is necessary. If, however, monitoring indicates
that adverse impacts may occur, a pump and treat system, similar
to the one installed for the portal plug, will be installed and
operated.
3
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6.
Operations and maintenance of the selected remedy.
Routine operations and maintenance of the installed
facilities will be required. This includes the surge ponds, the
water control measures, the monitoring systems, and the water
collection and interim treatment plant. .
~
These elements comprise the first remedial operable unit at
the California Gulch site. Subsequent operable units will
address public health and environmental impacts from mine
tailings and wastes, surface water in California Gulch, the
ephemeral tributaries to California Gulch, and the Arkansas
River, soils, slag, sediments, air, ground water, and biological
media.
DECLARATIONS
Pursuant to CERCLA, as amended by SARA, and the NCP, I have
determined that the selected remedy for Operable Unit I at the
California Gulch site is protective of human health and ~he
environment, attains all location-specific and action-specific
Federal and State req~rements that are applicable or relevant
and appropriate (ARARs) to this remedial action, and is cost- .
effective.
The remedy is not expected to attain all the chemical-
specific "requirements. Because of the contribution of other
sources to surface water contamination, the remedy is not
expected to attain the degree of cleanup of surface wate~ set by
these chemical-specific requirements. Therefore, I have found
that a waiver is necessary under Section 121(d)(4)(A) of SARA. A
waiver is appropriate if the remedial action s~lected is only
part of a total remedial action that will attain a level or
standard of control at least equivalent to the legally applicable
or relevant and appropriate standard, requirement, criteria, or
limitation. The treatment facility component of the selected
remedy is an interim action designed to decrease the release and
threatened release of metals from the Yak Tunnel. It is only a
first step toward cleanup of California Gulch surface water and
is part of a total remedial action for the site. Response
actions in subsequent operable units, in combin~tion with this
selected remedy, will attain a level or standard of control at
least equivalent to ARARs.
The remedy satisfies the statutory preference for remedies
that employ treatment that reduces toxicity, mobility, or volume
as a principal element and utilizes permanent solutions and
alternative treatment technologies to the maximum extent
practicable.
4
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"
Because this remedy will result
remaining on site above health-based
remedial action will be conducted no
after the initiation of the remedial
health and the environment are being
action being implemented.
in hazardous substances
levels, reviews of the
less often than each 5 years
action to assure that human
protected by the remedial
~ ~ ..1- .J.~ /Fr'
Date
~ ()f~
J m J. 5~erer
Regional Administrator
Region VIII, U.S. Environmental
Protection Agency
,
5
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CONTENTS
u
I.
II.
III.
IV.
V.
VI.
Site Name, Location, and Description
Site
Status
Site History
Response History
Enforcement History
Site
Characteristics
Source of Contamination
Pathways of Migration
Public Health and Environmental
Impacts
Community Relations History
Alternatives Evaluation
Development of Alternatives
Description of Alternatives
Initial Screening
Detailed Description of Remaining
Alternatives
Detailed Analysis of Alternatives
Selected Remedy
Description of Selected
Cost of Selected Remedy
Statutory Determinations
Schedule
Remedy
References
Hydrogeologic Impact of Selected Remedy
Cost Estimates
Evaluation of Applicable or Relevant and
Apptopriate Requirements
Statement of Findings Concerning
Floodplains and Wetlands
Appendix A.
Appendix B.
Appendix c.
Appendix D.
i
Paqe
-
1
1
1
6
6
7
7
9
16
18
20
21
22
, 24
26
30
34
35
48
49
56
58
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TABLES
page
l Comparison of Metals Concentrations in Yak
Tunnel Discharge to Ambient Water 'Quality
Criteria 11
2 Comparison of Metals Concentrations Ranges
at Six Locations Along the Mainstem of
California Gulch to Ambient Water Quality "
Criteria 13
3 Comparison of Metals Concentrations on the
Arkansas River to Ambient Water Quality
Criteria 14
4 Comparison of Alternatives 31
5 Monitoring Program 43
6 Potential Adverse Short-Term Impacts Associated
with the Selected Remedy 51
7 Potential Adverse Long-Term Impacts Associated
with the Selected Remedy 52
FIGURES
1
2
3
4
5
6
Location Map
Location--Yak Tunnel and Major Laterals
Potentially Contaminated Media
Surface Water Sampling Locations
Schematic Showing Selected,Remedy for the'
Yak Tunnel
Monitoring Plan Map
2
3
10
. 12.
37
42 '
ii
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I.
SITE NAME, LOCATION, AND DESCRIPTION
w
The California Gulch site is in Lake County, Colorado,
approximately 100 miles southwest of Denver (Figure 1). The
Phase I Remedial Investigation (RI) study area, which
includes the City of Leadville (population 3,800),
encompasses an 11.5-square-mile watershed that drains along
California Gulch to the Arkansas River west of Leadville.
The California Gulch drainage basin ranges from 10,000 to
14,000 feet above mean sea level (msl) in elevation (EPA,
1987a) .
The RI conducted by the U.S. Environmental Protection Agency
(EPA) indicates that the area is contaminated with metals
including cadmium, copper, lead, and zinc emanating from
numerous abandoned and some active mining and minerals
processing facilities. A primary source of the metals
contamination is acid mine drainage from the Yak Tunnel into
California Gulch.
.
.
The Yak Tunnel (Figure 2) extends underground approximately
3-1/2 to 4 miles into Iron Hill and Breece Hill. The tunnel
collects ground water from numerous underground mines and
then discharges flow into California Gulch. '
Based on the annual average flow rate and annual average
dissolved concentrations, the Yak Tunnel discharges ~
combined total of 210 tons per year of cadmium, copper,
iron, lead, manganese, and zinc into California Gulch (EPA,
1987a). .
'This Record of Decision (ROD) addresses the Yak Tunnel as an
"operable unit" of the California Gulch site. Under the
National Contingency Plan (NCP), an operable unit is "a
discrete part of the entire response action that decreases a
release, threat of release, or pathway of exposure" (40 CFR
S 300.68[c]). Subsequent operable units will address mine
wastes, ephemeral surface water, ground water, soils, and
other environmental media.
II.
SITE STATUS
SITE HISTORY
Mining activities in Leadville began in 1859 when
gold-bearing placer deposits were found along California
Gulch. Since that time, mining activity has almost been
continuous, although there have been production cessations
or slowdowns because of economic conditions or labor issues.
An estimated 26 million tons of ore'were produced in the
Leadville Mining District from 1859 through 1986 (ASARCO,
1987) .
1
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I\J
MI. flOE"'
fOIlEDAY
\
FIGURE 1
LOCA TION MAP
Grind Junellon
.
c
O. L
\
:\...\..J
~,\ 'f
:\'" ,
(F~'.:.-.J
~-
@
o
SCALE Of MILES
.,
2
'-""""',,1\
,
~J Doulde.
::.{ .
. Q'
. ). 00enwe.
~/Geo.gclown
. Ludwin.
A
o
o
A, "u.
O~
Pueblo .
J
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. 8'8...a
w
I . .
,.ii.
\
r
,
'00 Fl. CON IOU" '"""'"''
'AU"
.. I
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FIGURE 2
lOCATION Of YAK TUHHEL
AHD MAJOR LATERALS
CA,1f OIlH.A out (;11 lIuf 5
t t AO\/It t t. CIH OIlAOIl
A.I. 0' "1"1"0 ..c"vlt.
.YA" IUN"lt
. ..AJOR , A II A.At
-------
In its comments on the Yak Tunnel Feasibility Study (FS)
(ASARCO, 1987), ASARCO Incorporated provided the fOllowinq
history of the Leadville Mining District: -
Leadvil~2 began as a gold camp in 1861 when prospectors
working the channels of Arkansas River tributaries
found gold-bearing placer deposits in California Gulch,
east of the present town. The placers were not
extensive and production declined rapidly. Some small
gOld-bearing lode veins discovered along the gulch
helped to keep the camp from dying out completely after
1868. In 1874, two men, curious about the "heavy sand"
that interfered with the recovery of gold in the placer
sluice boxes, investigated the composition of the
material. It proved to be silver-bearing lead
carbonate. Examination of outcrops on nearby hillsides
disclosed the source of the mineral, and Leadville's
importance as a mining district dates from this
discovery.
\'
As the search for ore became widespread, extensive
replacement deposits of lead and silver and, later on,
rich gold ores associated with fissure veins were
found. Copper, usually associated with the gold ,ore,
assumed minor importance. Zinc and manganese minerals
occurred with the lead-silver ores; they were of little
value in the early days,-but were later mined
extensively.
As the mines were deepened and mining areas expanded,
drainage became an economic factor in the operational
costs, particularly during periods of depressed metal
prices or labor unrest. The Yak Tunnel, which started
in 1895 as an extension of the Silver Cord Tunnel,
eventually reached a length of 3-1/2 miles and was the
first of two major efforts to improve drainage. The
second major effort, the Leadville Drainage Tunnel, was
started in 1943 and was finally completed as far as the
new Mikado shaft near Stray Horse Gulch in 1952.....
Depressions occurred in 1893, 1907, and 1930-34. Labor
trouble occurred in 1896, 1897, and 1919. During these
times, the majority of the mines in the Leadville
District were closed and flooded. Mininq also was
curtailed by low metal prices and by depletion of ore
reserves, which were not maintained in advance of
mining; therefore, economic production levels could not
be maintained.
With the advent of World War II, operatinq properties
in the district increased production as a result of the
federal support-premium price paid for copper, lead,
and zinc. During the war, the major portion of the
4
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recorded production came from processing old dumps by
the Ore and Chemical Company and John Hamm Milling
Company; however, production increases were recorded
from the Resurrection No.2, Fortune, Eclipse, and
He11ena shafts, as well. Ore output practically ceased
after 1957 when the Irene shaft was closed due to low
metal prices. .
In 1965, a joint venture between ASARCO Incorporated
and Resurrection Mining Company reopened the Irene
workings and substantial ore reserves were proven in
the down-dropped block in the eastern portion of the
Leadville district bordered by the Ball Mountain,
Weston, and Garbutt faults. In 1969, a new shaft, the
Black Cloud, was sunk in Iowa Gulch to access the newly
found ore reserves. The Black Cloud mine and mill went
into production in April 1971 and has operated
continuously since that time. The other significant
mine to operate in the district since the Resurrection
Mill shut down in 1957, is the Sherman Mine at the head
of Iowa Gulch. This mine, now owned by the Leadville
Corporation, was operated by Day Mines and the Hecla
Mining Company between 1976 and 1984, after which it
was shut down for economic reasons. ,
There are currently a few active, moderate-sized mining and
reprocessing ope~ations in the Leadville area. However,
since mining .activities began in Leadville, hundreds of
mines, numerous mills, more than 40 smelters, and several
placer operations have contributed to both the past economy
and current environmental conditions in Leadville.
o
Emmons et a1. (1927) identified 1,329 mine shafts, 155
tunnels, and 1,628 prospect holes in the Leadville Mining
District, which have an estimated aggregate length of
75 miles. In the surrounding area, Behre (1953) identified
an additional 1,800 openings of various types. These
workings comprise an extensive network of connected tunnels
and shafts.
The Yak Tunnel was constructed to dewater mines and to
facilitate mineral exploration and development. .The tunnel,
driven in 1895 to drain the Iron Hill mines, was extended
several times. The last extension was in 1923.
The tunnel now has several major laterals and drifts that
extend from the tunnel into the various mine workings.
ASARCO (1987) reports some of the connections off the tunnel
as follows: the Horseshoe, the Rubie, the North Mike, the
South Mike, the Ibex No.4, the Little Winnie, the
Resurrection No.1, the Fortune, the Resurrection No.2, and
the Dolly B. In addition, there are six working winzes:
the White Cap, the Cord, the Mike, the Willard, the My Day,
5
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and the Diamond. BPA e~timated that 60,000 f~et of tunnels
and major laterals and 55 to 74 million cubic feet of void
space are associated with the tunnel mining activities (EPA,
1987b).
The current physical condition of the Yak Tunnel is unknown
but is suspected to be poor. The last inspection, conducted
by ASARCO in 1983, disclosed that the tunnel roof was
generally weak and had caved in at many places.
RESPONSE HISTORY
.,
In 1982 and 1983, EPA conducted a preliminary evaluation of
the California Gulch site, which consisted of an assessment
of existing data and a site inspection. In 1983, the
California Gulch site was placed on the National Priorities
List of sites which are the highest priority for EPA
response action.
EPA began the RI of the site in 1984. The Phase I RI
report, which primarily addresses surface and ground water
contamination, was released in May 1987. . During the RI, EPA
determined that response actions for the site could be
separated into operable units to facilitate site'
remediation. EPA conducted a removal operable unit to
connect a household to the public water systp.m. EPA.also
developed a remedial operable u~it to decrease the release.
and threatened release of hazardous substances, pOllutante,
and contaminants from the Yak Tunnel.
In June 1987, EPA released a FS report and, in August, a
proposed remedial action plan for the Yak Tunnel operable
unit. EPA held a 90-day public comment period and a public
meeting to provide opportunity for public review and comment
on the FS report and proposed remedial action plan.
This ROD sets forth the remedy selected for the first
remedial operable ~nit at the California Gulch site. The
primary purpose of this remedy is to decrease the discharge
of contaminated water from the Yak Tunnel. Subsequent
operable unit studies are planned to address mine wastes and
ephemeral surface flow, and overall site conditions
including soils, slag, sediments, air quality, surface
water, and ground water.
ENFORCEMENT HISTORY
In 1982 and 1983, EPA identified seven parties as potentially
responsible for California Gulch site contamination based on
their ownership or operation of mining or minerals
processing facilities at the site.
6
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In the spring and summer of 1983, EPA sent notice letters to
Apache Energy and Minerals Company, ASARCO, C and H
Development Corporation, Hecla Mining Company, Robert Elder,
Resurrection Mining Company, and Rock Hill Mines Company.
In the letters, EPA notified the parties that they were
considered potentially responsible for the release of
hazardous substances, pollutants, and contaminants at the
site, and offered each party an opportunity to participate
voluntarily in a response action. EPA enclosed with each
letter a copy of a draft work plan for the RIfFS. None of
the potentially responsible parties agreed to prepare the
RIfFS or undertake response actions at the site. Therefore,
EPA performed the Phase I RI and the Yak Tunnel FS using
Superfund money.
In spring 1986, EPA identified and sent notice letters to
six additional potentially responsible parties: Atlas
Mortgage Company; Denver and Rio Grande Western Railroad
Company; Leadville Corporation; Leadville Silver and Gold,
Inc.; Newmont Mining Corporation;. and the Res-ASARCO Joint
Venture. Again, these parties were identif~ed based on
their ownership and operation of mining and minerals
processing facilities at the site.
,
.
In August 1986, the United States filed an action against
these 13 parties in the United States District Court for the
District of Colorado: United States v. A ache Ener v and
Minua-Is Co., No. 86-C-l (D. Co o. J.led Aug. 6, 986.
In this action, the United States seeks to obtain a cleanup'
for the site and recovery of past and future response costs.
In February of 1987, this case was consolidated with a
related State case titled Colorado v. ASARCO, Inc.,
No. 83-C-2388 (D. Colo. filed Dec. 9, 1983).
The United States will seek to have responsible parties
implement the Yak Tunnel remedy. Two of the defendants
proposed to conduct remedies for the tunnel. These
remedies, which were evaluated by EPA during the remedy
selection process, are discussed in the "Alternatives
Evaluation" section of this ROD.
have
III.
SITE CHARACTERISTICS
This section summarizes the nature and extent of the release
and pathways of exposure to hazardous substances,
pollutants, and contaminants discharged from the Yak Tunnel.
SOURCE OF CONTAMINATION
The Yak Tunnel and its laterals extend through sulfide and
carbonate ore bodies under Iron Hill, Breece Hill, upper
California Gulch, and upper Evans Gulch as shown previously
7
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(Figure 2). The suite of minerals that constitutes the ore
bOdies drained by the Yak Tunnel is a complex assemblage
including native copper, gold, and silver; and sulfides,
carbonates, and silicates of these and other metals (EPA,
1987b) The primary minerals are predominately sulfides of
iron, lead, and zinc. As discussed in the "Site History"
subsection of this ROD, these ore bodies have been
extensively mined.
!?
This mining activity has exposed mineralized ore deposits to
water and oxygen. Ground water in this area is derived
primarily from precipitation and snowmelt. Water percolates
into the ground and moves through the alluvium and bedrock
in cracks, fissures, faults, and mine workings. As
oxygenated ground water flows through the sulfide minerals,
it oxidizes the pyrite minerals to form sulfuric acid. The
acid dissolves. and mobilizes cadmium, copper, iron, lead,
manganese, zinc, and other metals and sulfates. The tunnel
and its laterals collect this metal-laden acidic water and
drain it to the tunnel portal.
Discharge from the Yak Tunnel is continuous with flow
ranging from 1 to 3 cubic feet per second (cfs). The
highest flows are during spring runoff when the tunne~
discharge contains the highest metals concentrations
resulting in the poorest water quality. . Sampling of Yak
Tunnel discharge at the tunnel portal through five quarterly.
sampling rounds during the Phase I RI indicateq the. presence
of hazardous substances (metals) in the following ranges of
concentrations in parts per billion:
q
Cadmium
Copper
Lead
Zinc
Range
(ppb)
195-520
731-5,730
9-117
50,100-101,000
Arithmetic
Mean
(ppb)
209
2,032
42
68,232
Hazardous
Substance
The arithmetic mean of the five sampling periods indicates
. an average flow of 1.47 cfs. At this average flow rate, the
Yak Tunnel discharges 604 pounds of cadmium, 5,874 pounds of
copper, 121 pounds of lead, and 197,253 pounds of zinc into
the environment every year.
In addition to this continuous discharge of hazardous
substances, the Yak Tunnel is subject to "surges" or sudden
releases of large quantities of water and sludge (EPA,
1987a). Due primarily to lack of maintenance, the tunnel is
deteriorating, and there are cave-ins and blockages in the
tunnel or the laterals. The tunnel flow can become dammed.
or trapped behind the blockages. Water then builds up .
behind the blockage and eventually breaks through, scouring
8
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the buildup of metal-laden sludge from the tunnel floor.
Water and sludge are then discharged through the tunnel
portal. A surge occurred in 1985 that lasted approximately
24 hours and released an estimated 1 million gallons of
contaminated water at an instantaneous peak flow rate of
10 cfs measured at the portal (EPA, 1987a).
PATHWAYS OF MIGRATION
After passing through the tunnel portal, metals from the Yak
Tunnel can move through various environmental media.
Figure 3 shows a conceptual model of the potentially
contaminated media and the pathways of contaminant migration
at the site.
Movement of metals through surface water in California Gulch
is a major pathway of migration. In turn, the surface water
is in active interchange with the shallow ground water
system along California Gulch (EPA, 1987a). Both surface
water and, to a much lesser extent, ground water discharge
to the Arkansas River surface water. Metals precipitate in
the surface water system and become a part of the sediments
in California Gulch and the Arkansas River. Contaminated
sediments may be scoured continuously durinq high flows and
move down California Gulch and the Arkansas River. If
exposed to air, contaminated sediments in the stream bed or
along the banks may become wind-borne and dispersed through
an air pathway. .
Surface water contamination is the major impa~t of the Yak
Tunnel discharge. Table 1 compares metals concentrations in
the Yak Tunnel effluent with EPA's ambient water quality
criteria for acute and chronic toxicity to freshwater
aquatic life (EPA, 1987a).*
*
In developing the ambient water quality criteria, EPA
determined that the acid soluble test method would be the
appropriate method for certain metals. Since there
currently is no EPA-approved acid soluble test method, EPA
recommends applying the ambient water quality criteria
using the "total" recoverable method (see EPA, Quality
Criteria for Water 1986, May 1986). During the Phase I RI,
EPA used both the dissolved and total metals methods to
analyze metals concentrations in surface water (see Phase I
RI Report Appendices). In this ROD, all water quality data
are reported as total metals. The total metals.method best
represents the potential toxicity in the surface water
chemistry of California Gulch. The use of total metals
concentrations may be overly protective in the Arkansas
River because of the different chemical environment.
9
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~
AIR J::
-
SURFACE SOLIDS
POINT SOURCE FLOWS TO
CALIFORNIA GULCH"
- tailing.
- Yak Tunnel
- Se..ge Tre.tment
PI.nt Outf.1I
- .'8g.
- ml.c. mine .pon.
- .011.
- .edlmenta
,
EPHEMERAL DRAINAGES
- Upper Gulch
- Oregon Gulch
-St." Ditch
- ,Le.dvllle Storm Dr.ln
,
- Other trlbut.ry dr.'n.ge.
0" -
, 1
~
GROUND WATER
SYSTEMS
CALIFORNIA GULCH
SURFACE WATER SYSTEM
I~
t
I SIDIMINT SYSTEM I
RIVER ~
I
I ARKANSAS
I
FIGURE 3
POTENTIALLY CONTAMINATED MEDIA AND PATHWAYS
10
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Table 1
COMPARISON OF METALS CONCENTRATIONS IN YAK TUNNEL
DISCHARGE TO AMBIENT WATER QUALITY CRITERIA
Concentrations
(ppb)
Metal
Ambient Water b
Quality Criteriaa,
Acute Chronic
Range Detected in the
Yak Tunnel Effluent
Cadmium
Copper
Lead
Zinc
3.9
18
82
120
1.1
12
3.2
110
195-520
731-5,730
9-117
50,100-101,000
aSee Appendix C of this ROD for detailed discussion of
Ambient Water Quality Criteria.
bvalues assume hardness of 100 mg/l CaC03.
Source:
EPA, 1987a.
,
Table 1 sho~s that the Y~k T~nnel di~charge would be acutely'
toxic to freshwater aquatic life, based on both high and low
metal concentrations' during the five quarterly sampling
periods of the Phase I RI. In addition, the observed
concentrations of these metals in Yak Tunnel discharge were
many times the chronic toxicity levels for freshwater
aquatic life. For zinc, the highest concentration in the
Yak Tunnel effluent was more than 900 times the chronic
toxicity level for freshwater aquatic life.
The Yak Tunnel is the major contributor to contamination of
California Gulch surface water. Above the Yak Tunnel,
California Gulch flows intermittently during spring runoff
and heavy rainstorms. Throughout much of the year, the Yak
Tunnel is the primary source of continuous flow for
California Gulch below the tunnel. Another source of
continuous flow is the Leadville sewage treatment plant,
which discharges treated effluent to lower California Gulch
below Stringtown.
During the Phase I RI, EPA periodically analyzed surface
water samples from six locations (SW-3A, SW-4, SW-4A, SW-7,
SW-9, and SW-12) along the length of the California Gulch
mainstream below the Yak Tunnel (Figure 4). This segment of
California Gulch, which is approximately 4 miles long, runs
adjacent to Leadville and through Stringtown befo~e it
discharges into the Arkansas River.
11,
-------
o
30
"
. SURFACE WATER
SAMPLING LOCA TIONS
FIGURE 4
SURFACE WATER SAMPLING STATIONS
C'
-------
Table 2 shows the range of metal concentrations at various
sampling locations for four metals of concern detected in
California Gulch surface water. For these metals, the acute
and chronic toxicity levels for freshwater aquatic life were
exceeded along the entire length of California Gulch below
the Yak Tunnel. At times, the observed contamination levels
ranged from hundreds to thousands of times greater than the
criteria value.
COMPARISON
WATER
Table 2
OF RANGES OF METALS CONCENTRATIONS WITH
QUALITY CRITERIA AT SIX LOCATIONS ALONG
MAINSTREAM OF CALIFORNIA GULCH
AMB!ENT
THE
Criteria and Concentrations
Sampling (ppb) Zinc
Locations Cadmium Copper Lead
Ambient Water
Quality
Criteriaa
,
. 3.9 18 82 120
Acute
Chronic 1.1 12. 3.2 110
Locat'ion
SW-3A 56-390 254-4,280 9.5-239 5,060-75,000
SW-4 178-395 810-3,980 32-270 50,390-75,900
SW-4A 200-285 778-1,390 52-55 6,440-56,100
SW-7 82-382 174-3,620 105-3,500 27,310-76,600
SW-9 105-384 441-3,470 146-4,740 27,000-77,300
SW-12 62-290 26-2,560 16-2,860 20,170-57,800
aVa1ues assume hardness of 100 mg/l CaC03.
Source:
EPA, 1987a.
California Gulch contributes to contamination of surface
water in the Arkansas River. In the Phase I RI, sampling
points were located both above and below the confluence of
California Gulch with the Arkansas River (Figure 4). Data
from these locations demonstrate the impact of California
Gulch on Arkansas River water quality (Table 3).
It should be noted that during the five sampling rounds,
lead and cadmium were not detected in the Arkansas River
upstream of the confluence with California Gulch. . Below the
13
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Table 3
COMPARISON OF METALS CONCENTRATIONS IN-THE
ARKANSAS RIVER WITH AMBIENT WATER QUALITY CRITERIA
Ambient Water Arkansas River
Quality Criteria Concentrations
C . a (ppb)
oncentratl.ons
(ppb) Sample Above Below
Metal Acute Chronic Date Confluence Confluence
Cadmium 3.9 1.1 11/84 BDLb BDL
3/85 BDL 23
6/85 BDL BDL
9/85 BDL 5.8
11/85 BDL 5.7
Copper 18 12 11/84 12 BDL
3/85 3.8 189
6/85 4 29
9/85 4.6 37
11/85 6 24
'
Lead 82. 3.2 11/84 BDL BDL
3/85 BDL 439
6/85 BDL 25
9/85 BDL 6.8
11/85 BDL 9.7
Zinc 120 110 11/84 331 1,625
3/85 637 5,630
6/85 132 709
9/85 353 2,060
11/85 391 1,870
a
bvalues assume hardness of 100 mg/l Caco3.
BDL = below detection limit.
Source:
EP A , 1 9 87 a .
confluence, the acute and chronic criteria were exceeded
during three of the five sampling rounds for cadmium.
Concentrations of lead exceeded the chronic criteria for
four out of five sampling rounds and exceeded the acute
criteria for one of the sampling rounds. The concentrations
of copper also exceeded both the acute and chronic criteria
below the confluence in four of the five sampling rounds.
Upstream from the confluence, the zinc levels were already
14
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relatively high: however, they increased more than five
times in concentration below the confluence with California
Gulch and exceeded both acute and chronic criteria.
As part of the Phase I RI, EPA estimated the contribution of
the Yak Tunnel to metals loading at the point of confluence
with the Arkansas River~ The Yak Tunnel was estimated to
contribute an average of approximately 80 percent of the
dissolved zinc and 85 percent of the dissolved cadmium that
leaves California Gulch and enters the Arkansas River
annually (EPA, 1987a). Other sources are also recognized as
contributing to the contamination of both the Arkansas River
and California Gulch (EPA, 1987a). During spring runoff,
the relative contribution of different sources may vary
substantially. Nevertheless, the Yak Tunnel is a major
source of contamination year-round.
In addition, metals in the Yak Tunnel discharge contribute
to contamination of the shallow alluvial ground water zone
associated with California Gulch. The Phase I RI indicated
that there is an interchange between California Gulch
surface water and the shallow alluvial ground water zone
below the Pendry Fault. Ground water monitoring indicated
that the upper 25 to 50 feet of California Gulch allu~ial
ground water are contaminated with cadmium, zinc, and other
metals and pollutants such as sulfates, which are associated
with Yak Tunnel discharge. The concentrations of various
metals in ground water ar~ in excess of both primary and
secondary drinking water standards (EPA,. 1987a) .
As illustrated in the conceptual model (Figure 3), metals
from the Yak Tunnel also contribute to contamination of the
stream sediment system. Metals in solution can become
separated from the solution, forming precipitates that become
part of the stream sediment system. These precipitates can
remain suspended or settle out of the water. Yellow boy is
an iron hydroxide precipitate and is a visual example of
this process, which can be seen throughout the length of
lower California Gulch. The sediment system's dynamic
character is demonstrated at high flows when the sediments
and precipitates are picked up from the stream bed and are
moved further downstream.
If sediments dry out because of reduced streamflow or
movement of the stream channel, contaminated ~aterials can
become wind-borne. Hence, metals from Yak Tunnel can become
more widely dispersed than simply through water transport.
The air pathway will be addressed in a subsequent operable
unit.
15
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PUBLIC HEALTH AND
ENVIRONMENTAL IMPACTS
The surface water, ground water, and air pathways of
contaminant transport may each result in exposure of living
organisms to hazardous substances. Plants can take up metals
from water and soils through their root systems and leaves.
Aquatic organisms can absorb metals. Domestic animals and
wildlife can drink contaminated water or consume plants or
other animals that have taken up metals. Humans can be
exposed through inhalation or ingestion of contaminated
water, sediments, and food. Consequently, metals can become
part of the food chain and may bioaccumu1ate in various
organisms.
Cadmium, copper, lead, and zinc are key metals of concern.
The following are brief summaries of the toxic effects of
these metals: .
o
o
Cadmium--Chronic exposure ~o cadmium in animals
and humans results in renal dysfunction,
hypertension, and altered liver and kidney
function. Cadmium is toxic to freshwater fish in
low concentrations (a few ppb). Cadmium'
interferes with normal osmoregulation, liver and
kidney enzymatic activities, and maturation of
reproductive organs. Trout species are sensitive
to cadmium and juveni~e fish are commonly more
sensitive than either eggs or adults. When
cadmlum, copper, and zinc concentrations occur
together, synergistic effects increase their
toxicity to freshwater organisms.
Copper--Copper is not acutely toxic to humans. It
imparts a taste to water at relatively low
concentrations (a few thousand ppb), which could
deter use of contaminated water. Copper is one of
the most toxic metals for aquatic organisms.
Chronic exposure to copper in concentrations.
greater than 12 ppb reduces growth and rate of
reproduction, may interfere with oxygen transport
across gill membranes, and has been reported to
reduce the ability of fish to orient themselves
properly.
o
Lead--Chronic exposure to relatively low
quantities of lead in humans can cause anemia,
loss of appetite, intestinal cramps, and fatigue.
Lead can bioaccumulate in humans, and exposure to
higher lead levels can cause permanent
neurological damage. . The gastrointestinal
absorption and retention of lead is greater in
children than in adults, so children are much more
16
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susceptible to the adverse effects of ingestion of
lead in water, food, and dirt. Chronic exposure
to lead concentrations of 13 ppb in rainbow trout
causes reduced hemoglobin production and changes
in red blood cells. Lead concentrations of a few
hundred ppb causes spinal deformities in brook
trout. Fish that are exposed to chronic and
subchronic levels of lead generally show changes
in their tissue structure. Fish eggs and
juveniles may be more sensitive to lead, and
several other metals, than the adults.
o
Zinc--Zinc is an essential element in humans and
is necessary for the biosynthesis of nucleic acids
and polypeptides. Zinc is rarely toxic to humans,
but its synergistic/antagonistic interaction with
other metals may cause problems. Susceptibility
of fish to zinc is largely species-dependent.
Rainbow trout and brook trout are fairly
susceptible to chronic zinc exposure. Juvenile
rainbow trout are about three times more resistant
than eggs. Water temperature and hardness
significantly influence the toxicity of zinc.
Zinc toxicity causes decreased growth, kidney
dysfunction,. gill damage, and alterations in
behavior. .
"Surface water contamination is the exposure mechanism of
primary concern for the Yak Tunnel operable unit. . Below the
Yak Tunnel portal, California Gulcp runs approximately
4 miles next to Leadville and through Stringtown before it
discharges into the Arkansas River (Figure 4). There is
unrestricted public access to the gulch for most of this
length. Children and adolescents are attracted to water for
exploration and recreation. Both children and adults may
make other recreational use of the stream. Through such
activities, people would be exposed to metals through
inadvertent ingestion of contaminated material.
The Arkansas River is heavily used for irrigation, livestock
watering, public water supply, recreation, and fisheries.
In the upper Arkansas River Valley, the primary uses' of the
Arkansas River are recreational and, secondarily, irrigation
and stock watering.
Further downstream, water from the Arkansas River is
diverted for municipal water supplies. Flow has been
diverted from the Arkansas River below Granite, Colorado, to
serve the cities of Aurora and Colorado Springs. Surge
events that mobilize sludges from the Yak Tunnel have
affected Arkansas River water use. In 1983, during an
inspection of the Yak Tunnel, ASARCO personnel released
sludge or "yellow boy" that had formed behind debris dams.
17
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The release turned a 20-mile stretch of the Arkansas River
orange for several days and forced downstream cities,
including Colorado Springs, Canon City, and Florence, to
turn off th~ir water intakes for 5 day~. After a surge in
1985, an orange plume, which eventually dissipated in the
Pueblo Reservoir, was seen more than 60 miles downstream.
Again, downstream water intakes were shut down.
The State of Colorado has designated segments of the
Arkansas River, including the stretch from the confluence
with California Gulch to Lake Fork, for various uses,
including Class 1 cold water aquatic life. This
classification covers waters that, based on water quality
levels, flow, and stream bed characteristics, could provide
a habitat that protects a wide variety of cold water biota
such as trout and other sensitive species.
However, biological studies indicate that habitat
degradation from metals contamination has reduced the
capacity of this segment of the Arkansas River to support
well-balanced aquatic populations. Below the California
Gulch confluence, both the quantity and variety of fish and
macroinvertebrate populations are reduced (Roline et al.,
1981). Evidence also suggests bioaccumulation of metals and
negative impacts on the reproductive capacity of trout
(Roline et al:, 1981; La Bounty et al., 1975),
There is also the potential for the exposure of humans to'
metals through ground water. The previously mentioned
shallow alluvial ground water zone was used as a source of
domestic water. During the Phase I RI studies, EPA
identified 33 existing wells. that were drilled into the
California Gulch alluvium. Many of these wells have been
abandoned because of poor water quality. In 1986, EPA
connected the one remaining household that used the aquifer
as a drinking water source to the public water system.
However, at this time, no steps have been taken to prevent
people from using their existing wells or from drilling new
wells into the contaminated alluvium.
As shown in Figure 3, there are multiple sources and
pathways of metals contamination in the Leadville area. The
remedy selected for the Yak Tunnel operable unit is designed
to address a major Source of contamination and to reduce
significantly the amount of metals released into the
environment. Other sources and pathways of exposure will be
addressed in subsequent operable units.
IV.
COMMUNITY RELATIONS HISTORY
From the beginning of the RIfFS process for the California
Gulch site, EPA has conducted community relations
18
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activi ties and sought 'the involvement of potentially
responsible parties. These activities have included
correspondence with potentially responsible parties and
members of the public, preparation of press releases and
fact sheets, and periodic meetings with elected officials,
potentially responsible parties, and the community to
discuss the Superfund process and the status of site
activities.
.
On July 7, 1987, EPA issued a press release announcing the
availability of the Yak Tunnel FS report. In July 1987, EPA
distributed a fact sheet describing the alternatives
evaluated to more than 100 people on EPA's mailing list and
notified the public of the opportunity to comment. EPA
placed copies of the FS report in the Lake County Library in
Leadville and in the EPA Region VIII library in Denver. EPA
also distributed copies of the FS report to more than
40 people,. including those who requested a copy during the
public comment period. EPA sent copies on July 6, 1987 of
the FS report to all defendants in United S~3tes v. Apache
Energy and Minerals Co. and invited their comments.
On August 17, 1987, EPA issued a press release announcing
the availability of the proposed remedial action plan'for
the Yak Tunnel operable unit. EPA placed. a full-page notice
in The Herald Democrat on August 20, 1987, which contained a
brief analysis of the plan and alternative 'plans that were
considered. The notice also provided information on the
comment period and the date set for a public meeting. EPA
sent copies of the proposed plan to the complete mailing
list and to each of the defendants in United States v.
Apache Enerqy and Minerals Co. The plan notified the public
and the defendants of the timing and procedures for comment.
Copies of the proposed plan were also placed in the Lake
County and EPA Region VIII libraries.
EPA also made copies of the administrative record available
in the Lake County and EPA Region VIII libraries on. .
September 15, 1987. EPA sent letters to each defendant
announcing the availability of the administrative record.
EPA also issued a press release on September 25, 1987, and
articles notifying the public of location and availability
of the record appeared in The Herald Democrat on October 1,
1987, and the Rocky Mountain News on October 2, 1987. EPA
responded to all requests made during the public comment
period by defendants and others for technical information
not yet available in the administrative record.
In addition to a 90-day public comment period, EPA held a
public meeting on the FS and proposed plan at the Lake
County Courthouse in Leadville on September 1, 1987. More
than 40 people signed the attendance sheet. Attendees
19
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4".
5.
raised comments and questions
the meeting, ASARCO presented
Tunnel operable unit remedy.
meeting also raised questions
EPA and the ASARCO proposals.
on a variety of issues. At
its own proposal for a Yak
The people present at the
and made comments on both the
A court reporter prepared a transcript of the meeting. A
copy of the transcript and all written comments received
during the comment period have been placed in the
administrative record. In addition, copies of the
transcript were sent to all people who made comments at the
public meeting.
.:)
Key community concerns expressed at the public meeting and
in written comments included the following:
1.
The technical and economic wisdom of rehabilitating the
Yak Tunnel to faci~itate drainage and minimize surge
events;
2
3 .
The importance of worker safety during rehabilitation;
Problems with the need for perpetual tunnel
maintenance, treatment plant operation, and slud~e
disposal;
The appropriateness and technical feasibility of
meeting the proposed cleanup criteria; and
The potential economic impact of the proposed remedial
measures on the future of the Leadville mining
industry.
These issues are addressed in the "Selected Remedy" section
of this ROD and the Responsiveness Summary.
V.
ALTERNATIVES EVALUATION
As part of the FS, EPA developed and evaluated 11 remedial
alternatives for the Yak Tunnel in accordance with CERCLA
(as amended by SARA), the NCP, and EPA's "Interim Guidance
on Superfund Selection of Remedy", December 24, 1986 (OSWER
Directive No. 9355.0-19). In addition, EPA has evaluated
alternatives proposed by ASARCO and the Leadville Corporation.
Under Section 121 of SARA, EPA must select a remedial action
that is protective of human health and the environment, that
is cost-effective, that attains federal and state
requirements that are applicable or relevant and appropriate
(ARARs), and that uses permanent solutions and alternative
treatment technologies or resource recovery technologies to
the maximum extent practicable. Additionally, SARA
20
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Section 121 and EPA guidance documents establish a
preference for remedies which employ treatment which
permanently and significantly reduces the mobility,
toxicity, or volume of hazardous substances as their
principal element. This section summarizes how EPA's
selection process addresses these requirements.
remedy
DEVELOPMENT OF ALTERNATIVES
Alternatives for the Yak Tunnel operable unit were developed
based on consideration of specific site and waste
characteristics (see Table 5-1 of the FS report). From the
universe of possible response actions, EPA defined a set of
response actions and associated technologies that could
address the specific site and waste characteristics (see
Tables 5-3 and 5-4 of the FS report). An example of the
results of this process was the elimination of incineration
from further consideration because metals, such as the
contaminants from Yak Tunnel, are not destroyed by heat.
Section 121(b) (1) of SARA requires an assessment of
permanent solutions and alternative treatment technologies
or resource recovery technologies that, in whole or in part,
will result in a permanent and significant 4ecrease in the
toxicity, mobility, or volume of the hazardous substance,
pollutant, or cont~minant.. As part of this assessment, EPA,
evaluated permanent solutions and alternative treatment.
processes that included chemical treatment and reprocessing.
Before the technologies were assembled into ~emedial action
alternatives, they were categorized as either source control
Qr management-of-migration measures and were pre screened
based on their suitability to abate the threat from the Yak
Tunnel effluent. Source control measures are designed' to
control the source of contamination at or near the area
where the hazardous substances were originally located. For
this operable unit, the sulfide zones exposed by mining
activities are considered as the "source" of contamination.
Management-of-migration actions are taken to mitigate the
impact of the Yak Tunnel discharge. The results of this
prescreening were presented in Tables 5-7 and 5-8 of the FS
report.
EPA then assembled the remaining technologies and/or
disposal options into 10 remedial action alternatives.
Pursuant to the Interim Guidance on Superfund'Selection of
Remedy, EPA included alternatives ranging from those that
would eliminate the need for long-term management (including
monitoring) at the site, to alternatives involving treatment
that would reduce toxicity, mobility, or volume as their
principal element. Further., a no-action alternative was
included as required by Section 300.68(.f) (1) (v) of the NCP.
21
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In addition to the 11 alternatives developed and evaluated
in the FS report, EPA has added the two alternatives
proposed by defendants.
DESCRIPTION OF ALTERNATIVES
The remedial alternatives evaluated in the FS report were
developed to accomplish the following:
1.
Seal the underground workings to eliminate the outflow
of contaminated water (reduce or eliminate the need for
long-term management) ;
2.
Remove and process the sulfide mineral zone (reduce the
need for long-term management) ;
Treat the contaminated outflow prior to discharge to
the environment (reduce mobility and toxicity); or
3.
4.
Combinations of these alternatives.
These remedies are listed below as Alternatives 1
through 10. Alternative 11 is the no-action alternative.
The alternatives proposed by ASARCO and Leadville'
Corporation are listed as Alternatives 12 and 13,
respectively. .
2.
3.
4.
L.
Mine Void Backfill--This alternative would involve
backfill~ng the tunnel, the laterals, and the mined-out
voids with mine tailings, waste rock, natural fill, or
concrete to stop water infiltration and halt the
oxidation process.
Total Plugging of the Yak Tunnel--Several discrete
concrete plugs would be constructed within the tunnel.
The water that backs up behind the plugs would flood.
the sulfide zone, reduce the oxidation pro~ess and,
thereby, prevent the discharge of contaminated water.
Mininq and Disposal--The sulfide zone
out and disposed of in an appropriate
halting the in situ oxidation process
of metals.
would be mined
landfill, thus
and the release
Mining, Treatment, and Disposal--This alternative is
similar to Alternative 3 with the exception that
economically valuable metals would be recovered from
the mined sulfide rock prior to disposal. This would
significantly reduce the metal content of the waste
requiring land disposal and, thereby, offset disposal
costs.
22
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5 .
Collection, Treatment, and Discharge--This alternative
would involve rehabilitating the Yak Tunnel to maintain
its function in collecting the contaminated water.
Shafts would be sealed and surface water diversions
would be installed to minimize the inflow of snowmelt
and precipitation to the Yak Tunnel and mined areas.
Surge control ponds would be built to regulate the
outflow from the tunnel and a water treatment facility
would be constructed that would discharge treated
effluent to the lower reaches of California Gulch or
the Arkansas River. Among the considered treatment
options were the following:
o
Chemical treatment using a lime
neutralization plant or ponds:
Chemical treatment using selective
precipitation to recover valuable minerals
from the water:
o
o
Biological treatment using wetlands: and
o
A secondary treatment stage to further
improve the effluent quality.
,
6.
EPA identified Alternative 5 as the preferred
alternative in the proposed remedial action plan but
retained the possibility of partial plugging.
Partial plugging, Collection, and Discharge--This
alternative would involve constructing one or more
discrete concrete plugs in the upper reaches of the Yak
Tunnel to reduce the amount of the outflow discharged
to the lower reaches of California Gulch or the
Arkansas River.
7.
Partial Plugging, Collection, Treatment, and
Discharge--This alternative combines Alternatives 5 and
6, incorporating both the installation of one or more
discrete plugs and treatment of any remaining discharge.
The plug(s) would reduce the quantity of contaminated
outflow and, thus, reduce the size of the tr"eatinent
facility and amount of tunnel rehabilitation required.
8.
Partial Mining and Disposal, and Partial plugging,
Collection, and Discharge--This alternative is a
combination of Alternatives 3 and 6.
9.
Partial Mining, Treatment, and Disposal, and Partial
plugging, Collection, Treatment, and Discharge--This
alternative combines Alternatives 4 and 7.
23
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10.
11.
12.
13.
Institutional Contro1s--In this alternative, deed and
access restrictions would be used to reduce public
exposure to metals in the Yak Tunnel discharge.
No Action--No remedial actions would be performed.
ASARCO Proposal--ASARCO proposed total plugging of the
tunnel with a series of four concrete plugs. In
addition, surge ponds would be constructed, the ground
surface would be sealed to prevent inflow, and the mine
water would be treated through in situ lime treatment
by lime injection. This proposal incorporates elements
of Alternatives 2, 5, and 7 with the addition of the
in situ, rather than external, water treatment.
Leadville Corporation Proposal--Leadvil1e Corporation
proposed to install a plug in the Yak Tunnel below the
Resurrection Mine workings. This is a specific
proposal for implementation of one element, the.
Resurrection plug, common to Alternatives 2, 6, 7, and
12. Leadville Corporation also proposed pumping,
treatment, and discharge of water to Evans Gulch from
behind the plug, until its mining operations cease.
INITIAL SCREENING
,
Pursuant to Section 300.68(g) of the NCP and EPA's Interim
Guidance on Superfund Selection of Rem~dy, EPA conducted an
initial screening of the 11 alternatives based on
implementability (acceptable engineering practices) ,
effectiveness, and cost. Table 7-1 in the FS summarizes the
initial screening process. Alternatives 1, 2, 3, 4, 6, 8,
9, and 10 failed to pass the initial screening for the
reasons described below.
Alternative 1
Alternative 1 consists of filling mine void spaces and rock
fractures with mine tailings, waste rock, natural fill, or
concrete to reduce water infiltration and reduce the sulfide
oxidation process. This alternative was eliminated because
it may not be technically feasible to fill all the mine
voids and halt the oxidation process. If the mine void
spaces were to be filled, the alternative would probably not
be effective in reducing the generation of acidic ground
water since flow through the surrounding sulfide rock would
still occur.. This acidic water could seep to California
Gulch and possibly to other areas. The alternative was also
eliminated because it would cause extensive environmental
damage to the ground surface when the required access roads
and drill pads are built to inject the grout and other fill
materials into the mine voids. Alternative 1 far exceeds
the cost of other alternatives but does not provide
24
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substantially greater public health and environmental
protection, or technical reliability.
Alternative 2
Alternative 2 consists of totally plugging the Yak Tunnel by
a series of plugs in an attempt to stop the discharge of
flow from the portal. This alternative was eliminated
because it would not be technically feasible to stop all
flow from the Yak Tunnel workings. The lowermost area of
the tunnel, the Iron Hill group of mine workings, is
relatively near the surface and has extensive shafts,
fractures, and mine workings. Once water had backed up
behind the lowermost plug, it would likely seep through
these conduits to the surface and consequently to California
Gulch. While many of these could be plugged, it is unlikely
that complete control of the seepage through surface sealing
can be achieved in the Iron Hill area. This alternative die
not include any activities to control or clean up acidic
seepage. As a result of the uncontrolled a~~dic seepage to
California Gulch, this alternative would no~ effectively
protect water quality.
.
Alternatives 3 and 4
,
Alternat1ves 3 and 4 ~oth entail removing the sulfide rock
by mining. Alternative 3 involves disposal of the removed
sulfide rock, while Alternative 4 considers recovering the
metals from the sulfide rock (resource recovery) to reduce
the metals content of the waste requiring disposal.
Alternatives 3 and 4 were eliminated because they were
considered to be unreliable, likely to create substantial
adverse environmental impacts, and extremely difficult and
expensive to undertake. First, identifying and removing all
sulfide rock may not be possible. If all sulfide rock were
not removed, the conditions resulting in the generation of
acidic ground water would persist, and neither Alternative 3
nor 4 would be effective in protecting water quality. .
Second, the environmental impacts of such a mining effort
would be substantial because it would entail exploration
drilling, rock removal, backfill to prevent subsidence of
mined areas, and transportation and disposal of the mined
material. In addition, both Alternatives 3 and 4 far exceed
the costs of other alternatives and still do not provide
substantially greater public health and environmental
protection, or technical reliability.
Alternative 6
Alternative 6 consists of pa~tial plugging, collection, and
discharge of the Yak portal drainage. The partial plugging
would reduce flow and metals concentration at the tunnel
portal. The discharge at the portal would be collected and'
25
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discharged either to California Gulch or the Arkansas River.
Hcwever, even with the reduction in volume and metals
concentration, the water discharged from the Yak Tunnel
would still contain high levels of metals. Therefore, this
alternative was eliminated.
Alternatives 8 and 9
Alternatives 8 and 9 are similar in that they entail partial
mining and disposal, and partial plugging, collection, and
treatment for both the mined materials (to remove the
sulfides and achieve resource recovery) and treatment of the
tunnel discharge. Neither alternative would achieve greater
reduction in mobility, toxicity, or volume of wastes than
Alternatives 5 or 7. Alternatives 8 and 9 were eliminated
for the same reasons as Alternatives 3 and 4; they are
unreliable, likely to create adverse environmental impacts,
and extremely difficult to undertake.
Alternative 10
Alternative 10 uses institutional controls to minimize the
impact from the Yak Tunnel. Institutional controls, such as
fences, culverts, and land use restrictions, are technically
feasible and relatively simple to implement. However,
implementation of institutional controls would .have no
impact on th~ generation and discharge of metal-laden acidic
water from the Yak Tunnel. Since Alternative 10 would
provide little benefit, if any, to protection of public
health and the environment, it was eliminated.
Alternatives 12 and 13
Alternatives 12 and 13 did not
since they were proposed after
However, EPA retained them, as
and 11, for detailed analysis.
receive initial screening
EPA had completed the FS.
well as Alternatives 5, 7,
DETAILED DESCRIPTION OF
REMAINING ALTERNATIVES
The five alternatives retained for further analysis include
elements of source control (tunnel plugging and flooding of
sulfide zones to control oxidation), management of migration
(collection and treatment of contaminated water), permanent
solutions (tunnel plugging, flooding of sulfide zones, and
surface sealing), and alternative treatment technologies
(collection and treatment of contaminated water). In
addition, several of these alternatives (5, 7, 12, and 13)
use techniques that may significantly reduce the mobility,
toxicity, or volume of hazardous substances.
26
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The five alternatives selected for detailed analysis are
described in detail below.
Alternative 5--Collection, Treatment, and Discharge
This alternative is a management-of-migration technique to
collect and treat the Yak Tunnel flow. The tunnel would be
rehabilitated to maintain its function as a drainage system,
which would control surges and releases of precipitates.
The portal flow would be routed through surge ponds in the
Resurrection Mill Yard. These ponds would be built to
control discharges during construction and then. would be
used as equalization ponds to control the flow to a
treatment plant.
Water would be pumped to a treatment facility located
outside the 100-year floodplain. The plant would use
chemical or biological treatment processes. Secondary
treatment would be added if necessary to meet cleanup
standards. After treatment, the water could be discharged
to either California Gulch or the Arkansas River. Waste
sludge from the treatment facility would be disposed of
onsite in a properly designed and maintained landfill.
,
A~ternative 7--partial Pluaqinq, Collection, Treatment, and
Discharge
This alternative uses both source control and
management-ox-migration technologies. Source control would'
be achieved by placing concrete plugs in the Yak Tunnel
below both the Resurrection and the Ibex-Irene mine
workings. These plugs would decrease acid mine drainage
flow rates from the portal by about 50 percent. Partial
plugging would also reduce the area of the tunnel and
laterals that would require rehabilitation and subsequent
maintenance. The remaining acid drainage from the tunnel
would be collected via the rehabilitated tunnel collection
system described in Alternative 5. The treatment plant
options (adjusted for reduced flow and waste disposal) would
be the same as those for Alternative 5.
Alternative 1l--No Action
Under the no-action alternative, there would be no
remediation of the Yak Tunnel discharge.
Alternative l2--ASARCO Proposal (Total Plugginq, Collection,
and In Situ Treatment)
During the public comment period, ASARCO proposed a detailed
alternative that uses both source control and management of
migration technologies (ASARCO, 1987). This alterna~ive
involves total plugging of the Yak Tunnel 'with placement of
27
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4.
concrete plugs below the Resurrection mine workings, in the
Irene-Ibex area, and near the portal. The water behind the
portal plug would be pumped to the surface, mixed with lime,
and subsequently discharged back into the mine workings'via
injection wells. The pumping, treatment, and reinjection
would continue until water quality within the mine workings
was acceptable. If necessary, water levels would be lowered
behind the portal plug and the pumped-out water would be
treated before discharge.
ASARCO also proposed diversion of surface water, construction
of surge ponds, and development of a monitoring network.
Since this combination of response actions was not evaluated
in the FS, a more detailed d~scription follows:
1.
Tunnel Plu~ginq. Concrete plugs would be installed at
four locat10ns in the Yak Tunnel: below the
Resurrection-mine workings, below the Ibex area, .in the
Irene lateral, and near the portal. The plugs would
minimize the migration of water from the mine workings
through the tunnel and would inundate a large portion
of the sulfide zone.
,
2.
Surface Water Diversions. To minimize the amount of
surface water infiltrating the tunnel, ASARCO proposed
constructing a surface water aiversion channel and a
ground water cutoff wall upstream of the diversion
channel,. and backfilling all shafts in the bottom of
upper California Gulch.' .
Surge Ponds. Surge ponds would be constructed on two
tailing impoundments located near the Yak Tunnel
portal. The surge ponds would be needed to protect the
downstream waters during construction of the tunnel
plugs. Once the plugs are installed, the surge ponds
would be dismantled. This component would also involve
stream channel relocation and stabilization of the two
tailings impoundments.
3.
In Situ Treatment. ASARCO proposes to treat the water
impounded behind the portal plug by injecting lime into
the old mine workings. The proposal consists of a well
and pump station in California Gulch, surface piping
to injection wells, and a portable lime addition
system. According to ASARCO, this in situ treatment
system would pump water from old mine workings, add
lime, and reinject high pH water into six major mine
workings. The high pH water would precipitate metals
and form a sludge, which would eventually settle out
and possibly seal the seeps. After determining that
the entire stored water volume has been adequately
treated, the injection process would be stopped until
28
-------
monitoring revealed the need for additional lime
neutralization.
5 .
Monitoring ar.d Continqency Plan. Several monitoring
wells would be installed around the periphery of the
Yak Tunnel hydrologic unit to establish baseline data
on water quality and levels and to detect any changes
as the treatment process proceeds. The California
Gulch pumping system would be used to control water
levels if surface seeps or other detrimental effects
are seen.
ASARCO did not provide information regarding the following:
2.
1.
Necessary pump rates and lime additions that would be
required under various hydrologic conditions~
3.
Data to permit evaluation of the adequacy of mixing
lime with metal-laden water in the underground workings
to' control the treatment process~ and
A specific program to locate seeps and monitor ground
water movement to determine whether the system is
working properly. '
Alternative 13--Leadville Corporation Proposal (Partial
Plugging and Discharge)
Leadville Corporation has also developed a proposed remedy
for a component of the Yak Tunnel. This remedy consists of
the following components:
1.
2.
Tunnel Plugging. A concrete plug would be installed in
the Yak Tunnel below the Resurrection mine workings.
The purpose of the plug is to prevent migration of water
from the Resurrection area through the tunnel portal.
Leadville Corporation estimated that this plug would
reduce the portal flow by 20 to 25 percent.
Collection and Treatment. During mining operations,
Leadville Corporation would collect and trea~ the mine
drainage water impounded behind the Resurrection plug.
After treatment, the water would be discharged to Big
Evans Gulch pursuant to a National. Pollutant Discharge
Elimination System (NPDES) permit. Sludge from the
treatment plant would be transported to the Leadville
Corporation's Stringtown Mill for processing and
disposal. After mining operations ceased in the
Resurrection workings, the mine drainage water would be
allowed to rise behind the Resurrection plug.
29
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DETAILED ANALYSIS OF ALTERNATIVES
CERCLA (as amended by SARA), the NCP, and EPA guidance
establish criteria to be considered in evaluating and
comparing alternatives. EPA's "Additional Interim Guidance
for FY '87 Records of Decision," dated July 24, 1987 (OSWER
Directive No. 9335.0-21), identifies nine key criteria to be
considered in the preparation of RODs:
o
Compliance with applicable, relevant or
appropriate requirements (ARARs)~
u .
o
Reduction of toxicity, mobility, or volume~
o
Short-term effectiveness;
o
Long-term effectiveness and permanence~
o
Implementability~
o
Cost~
o
Community acceptance~
,
o
State acceptance~ and
o
Overall protection of human health and the
environment.
Table 4 provides a summary of Alternatives 5, 7, 11, 12, and
13 with respect to each of these criteria. The key factors.
affecting remedy selection decisions are described in more
detail below for each alternative.
Alternative 5--Collection, Treatment, and Discharge
As described in the proposed remedial action plan (EPA,
1987c), EPA chose Alternative 5 as the preferred alternative
for the Yak Tunnel operable unit. This alternative, which
is supported by the State of Colorado and some members of
the community, was selected for the followinq reasons:
1.
The alternative would be protective of human health and
the environment because the treatment system would
improve the quality of the tunnel discharqe~
The treated effluent would attain chemical-specific
ARARs, except for water quality criteria for chronic
toxicity for freshwater aquatic life for cadmium,
copper, and lead~
2.
3.
The treatment system and sludqe disposal facility would
reduce the mobility of hazardous substances~
30
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4.
Tunnel rehabilitation would prevent or minimize surges;
5.
The alternative could be implemented with presently
available technologies; and
Maintenance using current engineering practices would
provide long-term effectiveness.
Nevertheless, there are also significant drawbacks to
Alternative 5. By maintaining "the tunnel and major
laterals, the sulfide zones would still be exposed to
oxygenated water, which would permit mobilization of metals
in the sulfide zones in perpetuity. The remedy would
require perpetual tunnel maintenance, treatment system
operation, and sludge disposal. Even if there were resource
recovery from the sludge, land disposal would still be
necessary. Leakage and loss of metals to the environment is
still a possibility, even with a properly designed disposal
system.
6.
In addition, tunnel rehabilitation may be technically
difficult, and there are short-term and long-term risks to
worker health and safety associated with tunnel
rehabilitation and maintenance. Some members of the'
community strongly oppose the tunnel maintenance component
and the associated need for perpetual treatment.
Alternative 7--partial plugging, Collection;"-Treatment, and
Discharge
This alternative would be protective of human health and the
environment through the decrease in both chronic metals
discharge and periodic surges. The remedy would reduce both
the volume of water to be treated and mobility of
contaminants through partial inundation of the sulfide zone
and blockage of water behind the plugs. The plugs would
reduce the amount of water flowing to the treatment plant by
approximately SO percent, compared to Alternative 5. As
with Alternative 5, the treated effluent would attain
chemical-specific ARARs, except for the water quality"
criteria for chronic toxicity to freshwater aquatic life for
cadmium, copper, and lead. In addition, the partial
plugging component would reduce the costs of tunnel
rehabilitation and maintenance, the capital and operating
costs of the treatment plant, and the costs and potential
environmental harm associated with sludge disposal. For
these reasons, this alternative has somewhat greater
community acceptance than Alternative 5.
Alternative 7 has drawbacks similar to those of
Alternative 5. Although of a lesser magnitude, perpetual
tunnel maintenance, treatment system operation, and sludge"
disposal would be required. There would also be similar,
- 32
-------
although reduced, threats to worker safety. There is also
uncertainty about how plugging would affect the quality and
flow of water behind the plugs. The primary concern would
be uncontrolled seepage or contamination of clean ground
water areas. Some members of the community are opposed to
the plugging component 'for these reasons.
Alternative 11--No Action
This alternative is not protective of public health and the
environment because the contribution of the Yak Tunnel to
contamination of surface water, ground water, and the
sediment system would continue unabated. In addition, the
risk of surges would continue, the chemical-specific ARARs
would not be attained, and there would be no reduction in
mobility, toxicity, or volume of the contaminants. This
.alternative is not acceptable to the State or the community.
Alternative 12--Total Plugging, Collection, and In Situ
Treatment
This alternative would be protective of human health and the
environment through the decrease in both chronic metals
discharge and periodic surges. The remedy would reduoe the
mobility and volume of contaminants released into the
. environment throUgh partial inundation of the sulfide zone
. and blockage of water behind the plugs. The in situ
treatment component of the remedy would further reduce the
mobility of contaminants and could minimize the need for
above-ground landfill disposal. of sludge. The remedy is
implementable using existing technology and the in situ
treatment component offers the potential for a permanent
solution. Some community members Supported this alternative
principally due to its potentially lower costs and possible
elimination of the need for perpetual operation and
maintenance.
Alternative 12 also has significant drawbacks. Due to' the
complexity of the mine workings, there is a significant
possibility that in situ treatment, as proposed, would not
achieve sufficient mixing and would, thus, ineffectively
treat water in all areas of the tunnel and connected mine
workings. Sludge from the treatment system may seal off
fracture flow paths causing short circuiting of the system,
thus rend~ring the treatment ineffective. Consequently, as
water levels rise behind the portal plug, there could be
uncontrolled seepage of water that would not meet
chemical-specific ARARs. Surface seeps of contaminated
water or movement of contaminated ground water toward clean
water areas could necessitate operation of a pumping and
treatment system, perhaps in perpetuity. This would negate
the benefits of in situ treatment and would result in
long-term maintenance and sludge disposal requirements.
33
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There is also a concern that buildup of sludge in the old
mine workings, which would result from in situ treatment,
would interfere with future resource development. The
concern is that it would be difficult to collect, remove~
and treat the sludge. The State believes that the
uncertainty associated with the effectiveness of in situ
treatment should be resolved through further study prior to
implementation of that system.
Alternative 13--partial Pluqqinq and Discharqe
This alternative would be protective of public health and
the environment in that it would reduce flow from the Yak
Tunnel by 20 to 25 percent. After mining ceases, the remedy
would reduce both the mobility and volume of contaminants
through inundation of mineralized zones and by blocking the
discharge of additional effluent from the Yak Tunnel. The
remedy is implementable using existing technology for
plugging and is expected to be a permanent remedy for that
. portion of the tunnel. The State and many community members
support construction of a plug below the Resurrection
workings.
This alternative is not a total solution. There would still
be substantial flow from the Yak Tunnel and the discharge
would exceed chemical-specific ARARs. Additionally, the
Leadville Corporation proposal did not provide for monitoring
or contingency planning, which would be necessary to ensure
that plugging pid not result in unacceptable environmental
impacts. .
VI.
SELECTED REMEDY
The goal of the selected remedy is to decrease the release
and threatened release of hazardous substances, pollutants
and contaminants from the Yak Tunnel into California Gulch.
The selected remedy consists of the following components: .
o
Surge ponds1
Tunnel plugging1
o
o
Water control measu~es, including sealing of drill
holes, shafts, and caved-in underground mine
workings to reduce surface inflow to the Yak
Tunnel system, and grouting of other areas to
minimize ground water outflow from the flooded
tunnel system after plugging; .
o
A monitoring system, including surface and ground
water components, to determine hydrologic changes1
34
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o
A water collection (pumping) system to control
water levels "behind the lower plug and an interim
water treatment facility using ponds (built
originally for surge control) as settling ponds;
o
Operation and maintenance of components of the
remedy; and
o
Contingency plans.
The components of the remedy are shown schematically in
Figure S. Many of these components are part of various
alternatives described in the previous section and were
evaluated in the FS. Specific design details of the
selected remedy will be developed during remedial design.
This remedy differs from the remedy described in the
proposed remedial action plan (EPA, 1987c). EPA initially
identified Alternative 5 as the preferred remedy but
retained the option to incorporate a partial plugging
component. Subsequently, EPA received additional
information during the public comment period and, after
taking these comments into consideration, re-evaluated
alternatives containing a plugging component and various
treatment options. Based on the comments received, EPA also
moqified the remedy to reflect concerns about integration of
the Yak Tunnel operable unit into the overall site remedy.
DESCRIPTION OF SELECTED REMEDY
The selected remedy for the Yak Tunnel operable unit
consists of the components described above. The remedy
incorporates a source control technology (tunnel plugging)
and a management-of-migration technique (a mine water
collection and treatment system). Each component is
described in more detail below.
Surqe Ponds
Before the pluqs are installed in the Yak Tunnel, a surge
pond system will be constructed at the portal. To protect
California Gulch and the Arkansas River from accidental
releases, the ponds will collect any surges of acidic
waters, sludges, or sediments from the tunnel caused by
construction. The ponds will be large enough to contain
approximately 8 million gallons of water, or about six to
eight times the discharge volume that was estimated during
the October 1985 surge event (EPA, 1987b). The ponds and
suitably sized ditches will be excavated to maintain a
working depth of about 10 feet. The ponds will be lined
with a synthetic membrane and clay to minimize leakage. A
35
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bypass channel, sized to accommodate the flow from a
100-year flood event from upper California Gulch, will be
built to protect the surge ponds. Once the tunnel plugs
have been installed, the ponds.will not be needed for surge
control. They will then be used as part of the interim
treatment facility, which is described later in this
subsection.
Tunnel plugging
A minimum of three concrete plugs will be installed in the
Yak Tunnel as shown in Figure s. The plugs will be
constructed in sound, low permeability rock, and will be
downgradient from each major group of interconnected mine
workings (Resurrection Group, Ibex-Irene Group, and the Iron
Hill Group). The Resurrection plug will be located in the
vicinity of the small rhyolite breccia pipe that separates
the Resurrection Mine Group from the Ibex-Irene Group.
Installation of the plug will reduce inflow to the Yak
Tunnel from the Resurrection group. The Ibex-Irene plug
will be located just to the west of the Weston Fault Zone
within the large mass of gray porphyry rock underlying
Breece Hill. This plug will reduce mine water drainage from
the Ibex-Irene group to the Yak Tunnel. The portal plug, to
be built just below the Iron Hill group of mine workings,
will probably be placed about 1,500 feet inside the tunnel
. portal because of the highly weathered rock (fractured) and'
generally unstable tunnel condition near the portal.
Access for construction of the Resurrection and Ibex-Irene
plugs can initially be gained through either the
Resurrection workings or the Irene 1,200 lateral (see
Figure 5). Construction access for the portal plug wi~l
require either tunnel rehabilitation or construction of a
new access shaft.
Plugging will seal off the major flow route for ground water
movement. As a result, ground water levels in the mine
workings and the surrounding rock will rise to a new
equilibrium level. The current equilibrium ground water
level in the vicinity of the Yak Tunnel is at the floor
elevation of the tunnel, which is approximately 10,330 feet
msl. The tunnel acts as a drain for the mine workings and
the surrounding fractured rock. It can collect surface
infiltration and ground water located in the rock mass up to
several thousand feet from the tunnel. This low ground
water level throughout the mine workings and mineralized
rock results in a maximum exposure of sulfide-bearing rock
where it is subject to oxidation. These conditions are
conducive to acid mine drainage formation and result in the
high metals concentrations in the Yak Tunnel portal flow.
The approximate maximum elevation of sulfide rock in the
Resurrection group of workings is estimated to be
36
o
-------
.
TO EAST FOAK-
ARKANSAS AIVEA
w
~.
1
WA TEl' COllECTION
. TREATMENT.
. PUMP ITHAU NE W
ACCESS SHAFT
. INTEAIM TREA TMENT
SYSTEM' PONDS
SURFACE WATER CONTROL
. IEALING OF SHAFTS
. GROUT CURTAINS
. IEALING OF CAVED STOPES
. IURFACE WATER DIVERSION
PLUGGING
. NEW SHAfT fOR ACCESS
fO POATAL PLUG
~ t.CCES8 fOR UPPER PLUGS
(IRENE 8200' LEVEL)
u...
"~/bl" ..0.' . ....., ..AL
,,'
~ ..0.' 0. m '.1.".. ...".,.
C".'O .'0"'. ',' '''.''''.0.'.1
.::1 "LU. 1 ...0...... .0""0. .'LL
NOT TO SCALE
,
FIGURE 5
SCHEMATIC SHOWING
SELECTED REMEDY fOR
THE YAK TUNNEL
CALIFORNIA GULCH
LEADVILLE, COLORADO
-------
10,700 feet msl and in the Ibex-Irene Group, 11,300 feet
msl. In the Iron Hill Group, it is at approximately
10,700 msl~ however, it rises to approximately 11,300 feet
msl in the unmined segment of rock between the Iron Hill
Group and the Ibex-Irene Group.
Plugging will cause ground water levels to rise to a new
equilibrium level. At this new level, the outflows through
fractured rock, to the surrounding regional ground water
bodies, or in some cases through 'surface seeps, would
balance the recharge. This new equilibrium level is,
therefore, a function of the average permeability and amount
of mining-induced fracturing of the rock mass surrounding a
group of mine workings behind a particular plug. The rise
in ground water level can, inundate all or portions of the
exposed sulfide rock, thereby preventing exposure to oxygen,
and hence, reducing the amount of acid mine drainage that
forms. A simple ground water balance model was developed to
determine the approximate impacts of plugging on ground
water level, flow directions, and quality. It is based on
the model used in the FS report. A detailed description of
the model and the results of the analyses are outlined in
Appendix A. A summary of the result is contained in the
following paragraphs. ,
Immediately following installation of the plugs, ground
water levels will begin to rise behind the plugs, reducing
flow from the Yak Tunnel to near zero. Based on estimates
of rock permeability, the equilibrium ground water level
behind the Resurrection plug is expected to rise to
approximately 10,750 feet msl. This should be sufficient to
inundate the sulfide rock and reduce acid mine drainage
formation to a minimum. Furthermore, since the surface
topography in this area is above 11,100 feet msl, no surface
seeps should develop. Should the Black Cloud operation
cease to pump its mine water, the ground water level in the
Resurrection area may increase to approximately 10,900 feet
msl. At this elevation, a ground water flow component from
the mine workings toward the Evans Gulch area could occur.
In addition, there is a possibility that the selected remedy
may affect the Leadville Drainage Tunnel (LOT), which is
owned by the Bureau of Reclamation. EPA recognizes the.
concern of the Bureau of Reclamation over the effect
plugging the Yak Tunnel may have on levels of ground water
contamination and flow. Currently, the Bureau is ~eriously
considering construction of a treatment plant to remove
38
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heavy metals from the effluent discharged from the nearby
LDT. Attention must be focused on avoiding a change in
quality or quantity of flow toward the area drained by the
LDT that would alter the LDT discharge and exceed the
capabilities of the Bureau's proposed treatment facility.
Once the Yak Tunnel is plugged, EPA's conceptual model
suggests a slight increase in ground water flow in.the
general direction of the LDT, from 10 to 25 gpm (0.02 to
0.05 cfs). EPA believes this potential increase in flow
will not adversely affect the Bureau's treatment facility.
However, if EPA has underestimated the actual change in flow
that results from plugging, as discussed below,. the selected
remedy includes an extensive ground water monitoring system
that is intended to identify any adverse change in flow or
contamination in a time frame that would permit the control
systems included in this remedy to alleviate the potential
problem. In any event, EPA intends that the selected remedy
be designed and implemented "in a manner that will not
adversely affect the Bureau's LDT treatment facility by
subjecting it to unanticipated ground water flow or
contamination.
The equilibrium level in the Ibex workings ~ehind the ,plug
is expected to rise to about 10,650 feet msl. In the Irene
area, the level is expected to be much lower due to the.
influence of mine water pumping from the Black Cloud "
workings. These levels are insufficient to inundate all the
sulfide rock; acid mine drainage formation will probably
continue. Ground water from this area is expected to flow
in a westerly and southerly direction. Because the
topography in this area is generally above 11,000 feet msl, .
no surface seeps are expected to result. Should the Black
Cloud Mine cease pumping, the equilibrium level would rise
to approximately 10,800 feet msl in both the Ibex and Irene
Groups. This level is still inadequate to prevent acid mine
drainage formation but is still low enough not to cause any
surface seeps in the area.
The equilibrium ground water level behind the portal plug is
difficult to predict because the rock in the area is
extensively fractured and faulted, and near-surface mine
workings are present. It is, therefore, not possible to
estimate the permeability of this rock mass with any degree
of reliability. Without sealing of these fractures,
contaminated mine water will seep to the surface at various
locations as the water levels rise behind.the portal plug.
As described below, the selected remedy includes sealing of
these highly fractured rock areas and other water control
measures. If these measures are successful and an
equilibrium level of 10,500 . feet msl can be achieved, much
of the sulfide rock exposed in the mine workings would be
inundated. However, sulfide rock at the eastern boundary of
39
-------
~he workings and in the un~ined rock between the Iron Hill
Group and the Ibex-Irene plug will still be exposed and
contribute to the development of acid mine drainage.
Due to the large, geologically complex area potentially
affected by installation of the portal plug, without
full-scale field testing it is impossi~le to predict the
effectiveness of plugging and sealing in controlling the
release of acidic waters. Should uncontrolled seepage
continue after extensive sealing, the water level behind the
plug wo.uld be lowered by using a pumping system to the point
at which seepage would not occur. Contaminated waters from
the workings behind the portal plug would be pumped,
treated, and released to California Gulch. Details of the
pumping and treatment system are discussed later in more
detail. .
Water Control Measures
During the RI, it was determined that there is recharge to
the Yak Tunnel drainage system from surface waters entering
through shafts and caved-in areas. This recharge adds to
the amount of contaminated waters generated in the mine
workings. To reduce infiltration to the system, actions
will be taken to seal shafts and other recharge areas, and
to prevent infiltration of surfa~e waters from known or
suspected recharge areas such as the White Cap lateral east
of' the Yak Tunnel portal. .'
As mentioned p~eviousl!, after the plug is install~d, water
levels will rise behind the portal plug. Fracture zones,
caved-in areas, and drill holes will become leakage points
that must be located and grouted with acid-resistant
concrete to prevent the surface discharge of acidic waters.
Additional geologic mapping, geophysical investigations, and
other site activities will need to be conducted during the.
design. phase to address the sealing of these surface
infiltration and leakage locations.
Monitoring
Because of the size and complexity of the Yak Tunnel system,
tunnel plugging presents a risk of uncontrolled seepage and
migration of contaminated ground water. Therefore, the
monitoring program is an integral part of the .remedial
action. The general objectives of the program are as
follows:
o
Define the preremediation ground water and surface
water conditions against which the impacts of the
selected remedy can b~ evaluated;
40
-------
Appendix A
HYDROGEOI.OGIC IMPACT OF SELECTED REMEDY
,
. .
-------
Appendix A
HYDROGEOLOGIC IMPACT OF SELECTED REMEDY
CONCEPTUAL BLOCK MODEL
Possible hydrogeologic impacts have been projected based on
a conceptual block water balance model of the ground water
system in the vicinity of the Yak Tunnel. This is the same
model that was used in the FS. The analysis, which is based
on limited data, is primarily intended to allow comparisons
to be made among plugging scenarios and to focus the
monitoring program on areas of possible concern. The
projections also provide an estimate of potential impacts of
the remedy under conditions that may not be realized in the
near future. For example, the operation of the Black Cloud
mine has an impact on the current hydrogeology of the Yak
Tunnel system. Currently, the Black Cloud operation is
pumping to dewater the mine workings. When pumping ceases,
there will be changes in the hydrogeologic regime. The
potential changes have been considered. The model
incorporates the ground water system in the immediate
vicinity of the Yak Tunnel as shown in Figure A.I. How this
model fits within the regional ground water system is ~hown
schematically in Figure A.2. The details of the model are
shown in Figure A.3: Figure A.4. shows the oxide/sulfide
mineral interface at various: locations in the study area.
REGIONAL SETTING
It is important to recognize that the ground water model
covers only a portion of the regional ground water flow system.
The relationship of the Yak Tunnel model to the regional
system is indicated in Figure A.2 by inflows to and outflows
from the model area. These are referred to as 0 in
Figure A.2. ~odeled inflows and outflows in theRyak Tunnel
system change significantly under the various plugging
scenarios because of changes in the configuration of the
potentiometric surface. These changes influence ground
water flow directions and flow rates to or from the
surrounding regional system.
Under equilibrium conditions, the inflow and outflow from
the regional ground water flow system, including the Yak
Tunnel component, will be in balance. Since the total
regional flow is primarily controlled by the amount of
available recharge, this total flow is unlikely to change
significantly as a result of tunnel plugging. However, the
flews within the various components will change.
At the present time, the interc~nnected mining areas drained
by the Yak Tunnel act as a major discharge area for the
regional ground water system (se~ the area described as
A-I
-------
.
SUI" ..ce
(. I CM"'''' ,
A"'I'''''..' . .,
lEGEND
o
'.'00 ',000
'.000
'.000 ,.e. ,
. ~
7
\
'\.-
"
... .' " .....
"
'00 ,to CON'OUA '"'.""'-1.
. ,
,'0 I
'I
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", /,
.." '-'," , '/ "" ,.
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:.. ,/,...- /
i I- I"', ';';~.::::'.. ...... ........
\ ,-- ..' I?-- -- WAUR .AL "NCE
l._..; ;'7 /," .- . MOO(l COMrAAIMEHII
; ., / \...-/
fiGURE A.1
EI'EN' Of wAfER
BALANCE MODELING
CALli (lnN.A GUL ell OU, S
.lAUVIL U, CU, o.."OU
-------
REGIONAL GROUND
WATER SYSTEM
YAK TUNNEL
MODEL AREA
,I
.--.. >4~'~'
.~' -''''''''''''--'-'~-
.
~RO
QO
,ORO
~O
LIGEND:
YAK TUNNEL MODEL AREA'
QI . ..,... TIIA TI018
011. ...TE"CHANQI WITH IIEGIONAL GROUND
WATI" SYSTllli
0.- ..DIIOCIe 'LOW
QO. OUT'LOW (SII~AGI I 'O"TAL 'LOW)
REGIONAL GROUNDWATER SYSTEM
0111 = IN"L T"A TION
0110: OUT'LOW
FIGURE A.2
SCHEMATIC PRESENTATION OF YAK TUNNEL MODEL
IN RELATION TO REGIONAL GROUND WATER SYSTEM
A-3
-------
UADVllU
CE:>
):I
I
~
@~
.
"
FIGURE A.3
DEEP
GROUNDWAffR
flOW
DETAIL8 OF BLOCK MODEL
(FLOW8 CORRE8POND TO CURRENT WATER BALANCE
UNDER NORMAL FLOW CONDITION8 IN GPMt
-------
.1
' "
-. ..8.",.
" . I .
... " ''',VA''O'' CO..'OU.. 0'
" , , -......- Olla".U.."". ,,,,,.'AC'
, ..../, '
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... @ID A.,A 0' ......... AC""'"
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,.. 'I, CO..IOU. .....,"'",
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\
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.:.
fiGURE A.4
It f V A IIOH 0'
O.IOf/SUlflOt .HIl'" ACt
.'
....",- "..
r'~' ~~ ~ .-"
, i,
I
CAurOf&H.A Gill';" OlliS
l£AOVUlt. ~OlO"AOO
-------
"water Balance Model compartments" in Figure A.i) .. Other
discharge areas for tl1e regional ground water system include
the Leadville and Canterbury Tunnels, the Black Cloud mining
operations, lower Evans Gulch, lower California Gulch, and
the Arkansas River. Plugging the Yak Tunnel would raise
ground water levels and reduce ground water tlows toward the
tunnel. In some cases, flow directions may be reversed.
Reductions in regional ground water flows toward the Yak
Tunnel mining areas are balanced by increased inflows toward
the other discharge areas (see Figure A.2) .
MODEL RESULTS
The block model was used to simulate typical bedrock flow
auring normal current hydrologic conditions. These
conditions occur during the nonsnowmelt period from
approximately July through MArch and correspond to
steady-state flows. During the snowmelt period, significant
recharge to the ground water occurs. It is, however, not
anticipated that ground water flow directions will change
during this recharge period. The normal flow simulations,
therefore, adequately define ground water flow conditions
for the purpose of evaluating alternative remedialmeaeures.
The model was initially used to simulate-the ~urrent'flow
conditions with the ,Black Cloud mine dewatering operations.
A significant component of t~s ground water comes from the
Yak'Tunnel system. An additional model run was carried out
to determine the effect on Yak Tunnel flows should Black
Cloud c~ase its pumping operations.
Finally, the medel was used to simulate the conditions that
would occur when the selected remedy is implemented. As
before, two model runs were perfor.med to simulate the impact
of an operating and a nonoperating Black Cloud mine dewatering
system.
The results of the model runs are summarized in Tables A-l
and A-2 and in Figures A.5 through A.B. Table A-l shows how
the regional ground water flows are affected by the selected
remedy and the different Black Cloud pumping system'
operating conditions. Table A-2 summarizes the detailed
flow region around the Yak Tunnel and lists the estimated
ground water levels. The approximate oxide/sulfide'
interface is shown in Figure A.4. Comparing the projected
ground water levels shown in Table A-2 with the levels of
the oxide/sulfide interface indicates how much residual
sulfide rock remains above the ground water table. Any
sulfide rock above ground water will still contribute to the
formation ef acidic mine drainage.
The detailed results of the model studies are discussed in
the following subsections.
DE/CAGUll/021
A-6
-------
.
]'able A-I
GROUND WATER HUOEL WATER BALANCE COHPONENTS
Yak 'funnel Hodel Regional Ground Water System
Inflow Inflow
Tnflltra- Inter- Out- Infiltra- Jnter- Total SYIi-
tion Q] change QR Total fJow t1 on QIU change Qk Outflow tem Outflow
ConoJ it ions (1) (2) (J);(1)+(2) (It) (S) (6) (7);(S)+(6) (8)~(1t )+0)
Current
Normal flow, no plugs
Black Cloud Hine pumping 10 1$10 820 820 1,990 -810 1,180 2,000
Normal flow, no plugs '(
Black Cloud Hine not I
pumping 10 770 780 '780 1,990 -770 1.220 2.000
Selected Remedy
Resurrection, Ibex,
and I,orta I plugs
Black Cloud Hine
):10 pumping 10 S90 600 600 1,990 -S90 1.1t00 2.000
I
...... Resurrection. Ibex,
and portal plugs
Black Cloud Hine not
pUlipillg 10 33S JltS JltS 1.990 -3]S l,bSS 2.000
Notes: 1. All flows in gallons per minute (gpm).
2. A9sume 0RI ~ QI g 2.000 gpa.
"
I.
.;JIJ 1 IU'!4, J
-------
Table.A-;l
SUMMARY OF GROUND WATER FLOW I'ROJECTIONS UNIJER VARIOUS PLUGGING SC~NARIOS
To Tt) Flow
To Evans To To Deep D1vert~d to Water Level Elevations in Hine Areas
Portal Leadville Gulch California Black Ground Other Areas (steady-state. normal flow. ft 0151)
Flow Tunnel Art~a Gulch Area Cloud Water Because of North South
Scenarios !if!L (gll8) !~ (81Im) !IE!l ~ (gpm) Plu8 Resun'~ct ion Ibex Irene Iron Iron
Current (;ondh Ions
Normal flow, no
plugli
Black Cloud Hine
pUilping 490 10 10 240 70 0 10,400 10,400 10,000 10,350 10,350
t40rma I flow, no
plu~1i
Black Cloud Hlne
not pumping 675 10 10 65 40 ]0,400 10,400 10,600 10,350 10, J')O
Selected Remedy
»I Resurrection, Ibex,
I alld portal plUIS
00 Black Cloud Hine
pUilp I ng 0 25 170 315 90 220 10,750 10,650 10,000 10,500 l() , 500
Resurrection, Ibex,
and portal plugs
Black Cloud Hine
not pUlDplng 0 25 25 170 125 475 10,900 10,1100 10,800 10,500 l(), SOO
NOLe: Yak Tunnel portal elevation 18 10,))) feet (above msl).
.
,
IJE/CAt;U J I/m5. J
-------
INFIL TRATION
10
IBEX/IRENE
GROUP
GROUND WATER
190
RESURRECTION
GROUP
GROUND WATER
180
GROUND
WATER
120
NORTH/SOUTH
IRON HILL
GROUP
TO BLA'CKCLOUD
240
-GROUND AND
SURFACE WATER
235
TO LDT
10
YAK TUNNEL
'BEDROCK
70
TOTAL INFLOW 820 GPM
OUTFLOW 820 GPM
FLOW
480
LEGEND
l
FLOW IN GPM
FIGURE A.5
NORMAL FLOW, NO PLUGS
BLACK CLOUD PUMPING
A-9
-------
.
RECHARGE
10
GROUND WATER
1iO
IBEX/IRENE
GROUP
RESURRECTION
GROUP
GROUND WATER
180
GROUND'
WATER
80
NORTH/SOUTH
IRON HILL
GROUP
TO BLA.CKCLOUO
o
GROUND AND
SURFACE WATER
235
TO LOT
10
YAK TUNNEL
875
I BEDROCK
85
FLOW
TOTAL INFLOW 780 GPM
OUTFLOW 780 GPM
LEGEND
la
FLOW IN GPM
FIGURE A.8
NORMAL FLOW, NO PLUGS
BLACK CLOUD NOT PUMPING
A-10
-------
RECHARGE
10
GROUND WATER
135
IBEX/IRENE
GROUP
RESURRECTION
GROUP
GROUND
35
GROUND WATER
100
GROUND
WATER
120
NORTH/SOUTH
IRON HILL
GROUP
TO BLACK CLOUD
315
GROUND AND
SURFACE WATER
200
TO LOT
25
YAK TUNNEL
I BEDROCK
10
FLOW
TOTAL INFLOW 800 GPM
. OUTFLOW 800 GPM
LEGEND
l
FLOW IN PM
FIGURE A.7
NORMAL FLOW, RESURRECTION, IBEX AND PORTAL PLUGS
BLACK CLOUD PUMPING
A-ll
-------
RECHARGE
10
RESURRECTION
GROUP
GROUND WATER
15
IBEX/IRENE
GROUP
GROUND WATER
35
NORTH/SOUTH
IRON HILL
. . GROUP
..
TO LDT
25
YAK TUNNEL
o
/BEDROCK
125
FLOW
TOTAL INFLOW 345 GPM
OUTFLOW 345 GPM
LEGEND
(
FIGURE A.a
GROUND WATER
85
GROUND
WATER
20
,
TO BLACK CLOUD
o
GROUND AND.
SURFACE WATER-
200
FLOW IN GPM
NORMAL FLOW, RESURRECTION, IBEX AND 5IORTAL PLUG
BLACK CLOUD NOT PUMPING
A-12
-------
CURRENT CONDITIONS, BLACK CLOUD PUMPlNG
As shown in Figure A.5, normal base flow from the Yak Tunnel
is approximately 490 gallons per minute (gpm). About
24C gpm flows toward and is removed in the Black Cloud
workings. A small amount of ground water seepage,
approximately 10 gpm, flows toward the Leadville Drainage
Tunnel and into bedrock and alluvium along California Gulch.
About 70 gpm probably flows into the deep bedrock ground
water body below the Yak Tunnel.
CURRENT CONDITIONS, BLACK CLOUD NOT PUMPING
Should pumping operations at Black Cloud cease, the normal
portal outflow would increase by about 185 gpm. Due to the
higher water levels in the Irene area, the deep ground water
flow would increase slightly to about 85 gpm (from 70 gpm)-
(see Figure A.6) . .
SELECTED REMEDY, BLACK CLOUD PUMPING
After installation of the Resurrection, Ibex, and portal
plugs, Yak Tunnel portal ilow will be reduced to n~ar zero
(Figure A.7). The location of'the plugs is shown in
Figure A.4. Water levels in the Resurrection and Ibex
Groups wo~ld increase to approximately 10,750 ieet and
10,650 feet mean sea level (msl), respectively.- Sulfide
rock woul~ still be present above the water table and some
acidic mine drainage formation would persist. The
stabilized ground water level within Iron Hill Group is
difficult to predict. Assuming it is around 10,500 feet
above msl, then most of the sulfide rock would be inundated.
Deep ground water flow would increase to approximately
90 gpm and inflow to Black Cloud to 315 gpm. Ground water
se~page toward the Leadville Drainage Tunnel would increase
from 10 to approximately 25 gpm. Other than a slight
increase in the Leadville Drainage Tunnel flows, this is ~ot
expected to cause any noticeable ground water quality
impact. Seepage toward California Gulch in the Iron Hill
area would increase sUbstantially to approximately 170 gpm.
As the ground water level rises behind the portal plug, surface
seeps may develop to the west and the south of the portal
area. These areas are topographically lower than the ground
water levels behind the plug and contain fractured rock and,
in some cases, near-surface underground mine workings. The
area, therefore, is likely to offer the least amount of
resistance to ground water flow. Grouting and surface
stream channelization, which is expected to be part of the
selected remedy, will probably have to be carried out in
these critical areas.
Stream channelization will probably be required where
Caliiornia Gulch flows over the near-surface underground
A-13
-------
mihe workings ~hat connect to the Yak Tunnel. Grouting will
probably be required along and to ~he west 0: the
10,SOO-foot contour. Ext~nsive grouting may be required in
the area overlying the underground mine work~ngs immediately
to the nQrth of the Yak Tunnel portal.
In addition to the grouting program, seepage control will
also be accomplished by low~ring the ground water level
behind the portal plug by pumping. It is anticipated that
some optimum comb~nation of pumping and grouting will
ultimately be implemented. The stable ground water level
behind the portal plug may then be lower than the
10,500-foot level indicated.
SELECTED REMEDY, BLACK CLOUD NOT PUMPING
When the Black Cloud mine is not pumping and the
Resurrection, Ibex, and portal plugs are in place, the water
levels in the Ir~ne Group would increase significantly to
approxinLately 10,800 feet msl, while those in the
Resurrection Group would increase sl~ghtly to 10,900 feet
msl. However, acidic mine drainage would likely still occur
in these areas because some sulfide rocks could still be
exposed. The water level in the Iron Hill Group would not
be affected.
. .
The total deep ground water ~eepage from all m~ne workings
would in~rea~e to 125 gpm and an additional seepage of'
roughly 25 gpm from the Resurrection Group toward the Evans
Gulch area would occur. Due to its small quantity, this
seepage is not expected to cause any significant ground
. water quality deterioration in the Evans Gulch area. The
monitoring network, which shows both ground water flow and
quality conditions, will provide information to track this
condition. The 170-gpm seepage to California Gulch would
still apply and would have the potential for environmental
impact as described above with all three plugs installed.
A-14
-------
Appendix B
COST ESTIMATES
,
-------
Appendix B
COST ESTIMATES
INTRODUCTION
This appendix documents the estimated capital and operating
and maintenance costs for the selected remedy. The actual
costs will be determined by decisions made during the design
phase and if con~ingency measures must be implemented.
METHODS USED
Capital cost estimates were developed from approximate
quantities and appropriate unit rates. For grouting, a lump
sum estimate was used. Operations and maintenance (O&M)
costs were developed using percentages of capital costs or .
quantities and unit prices for consumables such as lime and
power. The capital cost unit rates and O&M percentage
estimates were based on the following published information:
o
o
o
NW Mining Association (1983)
Peters and Timmerhaus (1980)
Dodge (1982)
In addition, the professional experience and judgment of the
engineers invo-lved in technical support were used. ?hone
interviews were also conducted with mining construction
companies to obtain budget-level cost estimates for shaft
construction.
Table B-1 summarizes the basis for the unit cost estimates
for the various engineering components.
ASSUMPTIONS
The pumping and interim treatment system has been sized for
a capacity of 300 gpm. It is assumed that the average
operating flow rate will be 150 gpm. Capacities of other
components are listed in Table B-2. The table also includes
dimensions of key items such as channel lengths, shaft
depths, and so forth. Pond closure and reclamation costs
have not been included. Estimates of reagent consumption
are also shown. The grouting program costs were based on
typical costs associated with the construction of medium-sized
dams where grouting is used to reduce seepage flow through
abutments and foundations. .
The monitoring program costs we+e based on the conceptual
plan outlined in Section VI. It was assumed that no
existing shafts could be used for ground water monitoring
B-1
-------
Table ::-1
BASIS FOR CAPITAL AND CPERATING CGST ESTIMAT~S
Cost Items
Tunnel Rehabilitation
Shaft and Hoist
Ventilation and Lighting
Concrete Channel and
Flood Diversion
Shaft Sealing
Monitoring System
Water Treatment 5ystem"
Piping and Miscellaneous
Lime Equipment
Fence
Grouting
Power Supply
Maintenance Costs
Operating Supplies
Opera1:ing Life
Comments
Estimate based on experience with other tun-
nel rehabili1:ation projects
Estimate based on discussions with mining
construction companies
Estimate based on experience with other
underground projects
Estimate based on a nominal 19-foot channel
width and concre1:e at $300/yd including
excavation, forming, concrete, finishing, and
backfill where appropriate
Estimates based on experience with shaft
sealing
Estimates based on similar experience,on
o1:her projects
Estimate based on similar experience on other
projects
Lump sum estimate
Lump sum estimate
Cost based on 1982 Dodge Cost Handbook and
adjusted for inflation
Order-of-magnitude estimate based on typical
costs for foundation grouting at embankment
dams
Estimate based on experience with other
projects
Based on industry operating studies from
Peters and Timmerhaus
Based on industry operating standards from
Peters and Timmerhaus
Ten-year life for mechanical parts of treat-
ment facilities is assumed. All civil (con-
crete and soil) structures assumed to have a
50-year life
B-2
-------
Table B.:.2
COST ESTIMATES FOR SELECTED
REMEDY
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M.1f1JIMCI s.. a.sso
M.1f1JIMCI I.. J.ooo
M.lrDI8CI I.. no
~ ".00 7.366
. ... 118
..1f1JIMCI I.. 1,710
M.1If1JIMCI 1.IlOl 7,'00
- . '.00 I]O,~7
CIa8
S WO.]07
-'I.ITIA' 10.001 ",OJI
l-.ca.!
- UCIJIII 1.001 '.206
CDIT.~' 11.001 ...~
5 WO,S07
-------
and that approximately 50 percent of the identified well
locations would require two wells to monitor conditions in
different ground water bodies. It was also assumed that the
full program would be operated for the initial la-year
period and that the level of effort thereafter would be
reduced by 50 percent since operating experience with the
system would have been established. .
ACCURACY OF ESTIMATES
With the exception of the costs associated with the monitoring
and the grouting programs, the cost estimates are generally
within a -30 percent to +50 percent range of accuracy. Due
to the lack of site-specific geologic and geohydrologic
data, the costs associated with the monitoring and grouting
should only be regarded as order-of-magnitude estimat~s.
CO~~ARISON WITH COST FIGURES IN FS
.
The basis of this estimate is generally similar to that
developed in the FS. Exceptions primarily include the
grouting and monitoring programs outlined above. The costs
associated with the surge ponds have also been increased
over those presented in the FS. The ponds used in the
selected ~emedy incorporate a double liner and leach~te
- collection system. Since th~ ponds are deeper than the
"collection" ponds referred to in the FS, they are also
equipped with an underdrain to minimize uplift pressure on
the liner caused by ground water. The capital costs and
annual O&M costs are shown in Table B-2. The present worth
analysis at 10 percent,S percent and 3 percent discount
rates are shown in Table B-3.
B-4
-------
'I'able B-]
PRESEN')' WORT" ANAf.YSIS A'I' VARIOUS DISCOUN'I' RA'I'J:;S
PAiAMETERS
DISCOUII' lATE
ECOtIOIIC LIVES
CIVIL
MECHANICAL/ELECIRICAL
IOIIIOIIIIG
50.00
15.00
10.00
10.001
5.001
3.001
SINklllG fUll PRESENT VALUE
fACTORS Of A LUMP SUM
0.00887
0.05377
0.08723
0.1~~09
txJ
I
V1
PRESEIIT VALUE COS'S
TOTAL
CAPIIAl COSTS
OIIGINAl
REPLACE..'
CIVIL
£lEe/MECIi
AMllUAlCOSJl
OIH
CREDIT fC18 IEDUCED IOIIIOIIIIG
5.00 YEAI IEVIEW I
150,000
SINkiNG fUND PIESEIIT VALUE
fACTORS Of. A LUMP SUI
SlUING fUllO PRESEIII VALUE
fACTOIS Of A LUMP SUI
US
US
US
0.00086
0.03147
0.06275
0.00478
0.~6J4
0.07950
0.38554
0.61391
$ 17,716,36)
$23,260,235
$12,28),714
11,982,770
16,390
284,554
$ 5,332,~9
5,845,903
513,255
$ 13,002,972
11,982,770
182,2~2
837,960
$10,057,263
11,691,807
1,634,544
100,000
$100,000
200,000 $200,000
;'
$ 30,6M,6
$ 14,166,841
11,982,770
563,727
1,620,343
$ 16,184,~28
19,486,344 .
3,301,917
)U,3U $ 3U,3]]
I ,
-------
REFERENCES
Dodge.
Costs.
1982 Data from Dodge--Guide to Heavy Construction
McGraw-Hill. 1982.
Northwest Mining Association. An In-depth Study of New
Silver and Gold Mines. Short Course presented in Spokane,
Washington. ~ovember 1983.
Peters & Timmerhaus.
Chemical Engineers.
Plant Design and Economics for
1980.
,
B-6
-------
Appendix C
EVALUATION OF APPLICABLE OR RELEVANT
AND APPROPRIATE REQUIREMENTS
,
-------
, Appendix C
EVALUATION OF APPLICABLE OR RELEVANT
AND APPROPRIATE REQUIREMENTS
CONTENTS
I.
II.
III.
IV.
Page
INTRODUCTION
......................................... 2
CHEMICAL-SPECIFIC REQUIREMENTS ......................'. 2
A.
B.
c.
D.
Maximum Contaminant Levels for Drinking Water ..... 2
Aquatic Water Quality Criteria .................... 5
State Water Quality Standards ..................... 7
Antidegration Standard ............................ 9
LOCATION-SPECIFIC REQUIREMENTS ...................... 10
A.
B.
C.
D.
E.
F.
G.
National Historic Preservation Act ............... 10
Archeological and Historic Preservation Act ...... 10
Fish and Wildlife Coordination Act ............... 11
,
Clean Water Act (Section 404) .................... 11
Executive Order on Floodplain Management ......... 12
Federal and State Waste Management Requirements .. 13
Executive Order on Protection of Wetlands ........ 13
ACTION-SPECIFIC REQUIREMENTS ........................ 13
A.
B.
C.
D.
E.
F.
G.
H.
I.
5 u r 9 e Pond 5 ...................................... 1 5
Tunne 1 PI u99 ing .......... ~ . . . . . . . . . . . . . . . . . . . . . .. , 6 .
Water Control Measures .........................~. 16
Moni tor ing ...... '. . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . .. , 6
Water Collection System .......................... 17
Interim Treatment Facility....................... 17
Disposal of Sludge and Excavated Soil............ 18
Operations and Maintenance....................... 19
Worker Health and Safety......................... 19
C-l
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I.
INTRODUCTION
. .
EPA and the State of Colorado have identified chemical-
specific, location-specific, and action-specific applicable or
relevant and appropriate requirements ("ARARs") for the Yak
Tunnel operable unit of the California Gulch site. This
Appendix describes the ARARs identified and how they relate to
the selected remedy.
II.
CHEMICAL-SPECIFIC REQUIREMENTS
Chemical-specific ARARs set health or risk-based
concentration limits in various environmental media or discharge
limitations for specific hazardous substances, pollutants, and
contaminants. These requirements generally set protective levels
for the chemicals of concern in designated media, or else
indicate an acceptable level of emission or discharge of such
substances. EPA and the State have identified ARARs under the
Safe Drinking Water Act, Colorado safe drinking water
authorities, the Clean Water Act, and the Colorado Water Quality
Control Act. These are described below.
A.
Maximum Contaminant Levels for Drinking Water
The Federal Safe Drinking Water Act, 42 U.S.C. section 300g,
and Colorado drinking water authorities, Colo. Rev. Stat. section
25-1-107(x)-(y), provide for the establishment of drinking water
standards for public water systems. These standards are
"applicable" only to public water systems as defined by the acts
and regulations. However, they may be considered "relevant and
appropriate" as ARARs for potential ground water and surface
water exposure via drinking water. U.S..EPA, Superfund Public
Health Evaluation Manual (Oct. 1986). Because of the connection
between surface water and ground water in the lower California
Gulch shallow alluvial system which is an existing or potential
source of drinking water, drinking water standards are considered
ARARs for surface water in California Gulch.
The Safe Drinking Water Act "maximum contaminant l~vels" or
"MCLs" for inorganic chemicals are considered ARARs. MCLs are
enforceable standards establishing permissible levels of
contaminants in drinking water. See 40 C.F.R. section 141.2(c)
(1987). These standards are health-based, but have an economic
component. See 42 U.S.C. section 1401( 1 )(C). The MCLs currently
established for inorganic chemicals are listed in Table 1. The
Federal and State MCLs for these substances are identical. See
Colorado Primary Drinking Water Regulations,S Colo. Code Regs.
t003-1 (1981).
The Safe Drinking Water Act also provides for establishment
of secondary MCLs. These are designed to "control contaminants
C-2
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Table 1. Numeric Inorganic Chemical-specific ARARs (ppb)
MCLs1 Ambient Water Quality Criteria2
Acute3 Chronic4
Arsenic 50 360 190
Barium 1000
Cadmium 1 0 3.9** 1.1 **
Chromium 50
III 1700** 210**
VI 16 1 1
Copper 1000* 18** 12** .
Cyanide 22 5.2
Fluoride 2000*
Iron 300* 1000
Lead 50 82** 3.2**
Manganese 50*
Mercury 2 2.4 0.012
Nickel 1400** 160**
Nitrate 10000
Selenium 10 20 5.0
Silver 50 4.1**
Sulfate 250000*
Zinc 5000* 120** 110**
* Secondary Maximum Contaminant Levels
** Hardness dependent. Value set at hardness of 100 mg/L
CaC03. .
1. Maximum Contaminant Levels. These include National Primary
Drinking Water Regulations, 40 C.F.R. section 141.11(b) (1987)
C-3
-------
Table 1 (cont.)
(maximum contaminant levels for inorganic chemicals), and
National Secondary Drinking Water Regulations, 40 C.F.R. section
143.3 (1987) (secondary maximum contaminant levels for inorganic
chemcials). The State maximum contaminant levels are identical
to the Federal levels. See Colorado Primary Drinking Water
Regulations,S Colo. Code Regs. 1Q03-1 (1981).
2. Ambient Water Quality Criteria values for freshwater aquatic
life are taken from EPA's "Quality Criteria fOr Water 1986" (May
1986) (and Update #2 dated May 1, 1987) and "Ambient Water
Quality Criteria for Selenium-1987 (Sept. 1987).
3. These criteria are the one-hour average concentrations that
are not to be exceeded more than once every three years on
average.
4. These criteria are the four-day average concentrations that
are not to be exceeded more than once every three years on
average.
C-4
-------
in drinking water that primarily affect the aesthetic qualities
relating to public acceptance of drinking water." 40 C.F.R.
section 143.1 (1987). The regulations note that secondary MCLs
"in the judgment of the Administrator [of EPA] are requisite to
protect the public welfare." 40 C.F.R. section 143.2(f). The
Federal secondary MCLs for inorganic chemicals are listed in
Table 1. In addition to those listed, there are secondary MCLs
for chloride, color, corrosivity, fluoride, foaming agents, odor,
pH, and total dissolved solids. The State of Colorado has not
promulgated secondary MCLs.
EPA anticipates that the selected remedy will not achieve a
degree of cleanup in lower California Gulch surface water that
attains primary and secondary MCLs. The Phase I RI identified
numerous sources that contribute to metals loadings in lower
California Gulch. These include mine wastes, tailings, and slag
in the California Gulch drainage basin and in its tributaries.
The tunnel plugging and interim treatment facility components of
the selected remedy will achieve substantial reductions in the
contribution of the Yak Tunnel to metals loadings in California
Gulch. However, this operable unit is not the total remedy for
the site. It will be necessary to develop and evaluate
additional source control measures, including one or more
permanent treatment facilities, to attain or exceed drinking
water ARARs for specific metals.
B.
Federal Ambient Water Quality Criteria
Section 304(a) of the Clean Water Act, 33 U.S.C. section
1314(a), requires EPA to develop ambient water quality criteria
related to protection of human health and aquatic life. EPA has
developed criteria for numerous substances. The Federal water
quality criteria are not directly enforceable and are therefore
not "applicable" to the cleanup. However, under SARA and EPA
guidance, they may be considered "relevant and appropriate" under
the circumstances of the release or threatened release. See
Interim Guidance on Compliance with Applicable or Relevant and
Appropriate Requirements, 52 Fed. Reg. 32,496, 32,499 (1987).
Under section 121(d)(2)(A) of SARA, 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." SARA 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. section
9621(d)(2)(B)(i).
C-s
-------
EPA has determined that the ambient water quality criteria
for acute and chronic toxicity to freshwater aquatic life are
relevant and appropriate as ARARs for surface water in California
Gulch and the segment of the Arkansas River from the confluence
with California Gulch to Lake Fork. The values for the metals of
concern are listed in Table 1. EPA's determination is based on
the following considerations. .
1 .
Existing or Potential Uses
The State of Colorado has classified the stretch of the
Arkansas River from immediately above California Gulch to Lake
Fork for uses including "Class 1 cold water aquatic life." 5
Colo. Code Regs. 1002-8, p. 10.41. Section 3.1. 13 ( 1 ) (c) (i) of
the State regulations entitled "The Basic Standards and
Methodologies" defines this use as follows:
These waters provide, or could provide, a
habitat consisting of water quality levels
and other considerations such as flow and
streambed characteristics which do or could
protect and maintain a wide variety of cold
water biota, including sensitive species.
Cold water biota are considered to be life
forms, including trout, in water where
temperatures do not normally exceed 20
[degrees centigrade].
,
The Federal water quality criteria for freshwater aquatic life
are consistent with this use classification.
California Gulch has not been classified for particular
uses. However, section 3.1.9(2) of The Basic Standards and
Methodologies states that "[e]ffluent flows which reach a
classified body of water, even though the discharge point is to
water not yet classified, must be of a quality which will not
cause the standards of the classified water to be violated." 5
Colo. Code Regs. 1002-8. The federal water criteria are
consistent with this regulation. EPA plans to conduct a use
attainability analysis. of California Gulch to determine whether
it would be appropriate to refine this cleanup goal in a
subsequent operable unit.
2.
Environmental Media Affected
Based on the findings of the Phase I RI, the environmental
media affected by the releases and threatened releases from the
Yak Tunnel include surface waters in California Gulch and the
Arkansas River. The selected remedy includes discharge of
treated effluent into California Gulch surface water. Under
Section 3 of the FS, existing or potential aquatic life in
C-6
-------
California Gulch and the Arkansas River can be identified as
receptors qf contamination from the Yak Tunnel.
3.
Purposes of the Criteria
The water quality criteria for acute and chronic toxicity to
freshwater aquatic life were developed to protect freshwater
organisms and their uses. These criteria are based on an
evaluation of toxicity studies relating to species similar to
those which are or-could be present in the "Arkansas River or
California Gulch, to the extent that physical habit~t
requirements are met.
4.
Latest "Information Available
EPA has relied on the latest criteria documents available in
making the determination that federal water quality criteria are
relevant and appropriate under the circumstances of the release
from the Yak Tunnel. See Quality Criteria for Water 1986 (May
1986 and Update No.2, dated May 1, 1987) and Ambient Water
Quality Criteria for Selenium--1987 (September 1987).
EPA has also developed ambient water quality criterla for
protection of human health. For most chemicals, there are human
health criteria for two different exposure pathways: ingestion
of aquatic organisms and ingestion of both aquatic organisms and
drinking water. EPA is still formulating a position with respect
to the use of ambient water quality criteria for protection of
human health. See 52 Fed. Reg. 32,499 (1987). EPA will evaluate
the use of these criteria in a subsequent operable unit.
EPA anticipates that the selected remedy will not achieve a
level or standard of control that meets water quality criteria in
the California Gulch nor in the Arkansas River. As discussed
above, there are numerous sources of metals loadings to
California Gulch that will not be addressed as part of this
operable unit. in addition, as discussed in Section III of this
ROD, the Arkansas River exceeds the fresh water aquatic life
water quality criteria for copper and zinc above the California
Gulch confluence. To the extent that other sources "can be
addressed under CERCLA, it will be necessary to develop and
evaluate alternatives for remedial action in subsequent operable
units that will attain or exceed ARARs to protect aquatic life.
In addition, EPA and the State are now conducting further work on
standards and cleanup for the Arkansas River. EPA will re-
evaluate the appropriateness of the ambient water quality
criteria for the Arkansas River in a subsequent operable unit.
C.
State Water Quality Standards
Section 303 of the Clean Water Act, 33 U.S.C. section 1313,
provides for promulgation of water quality standards by the
C-7
-------
States. The standards consist of designated uses of water and
water quality criteria based on the designated uses. 40 C.F.R.
se6tion 131.3(i). The criteria aie "elements of State water
quality standards, expressed as constituent concentrations,
levels, or narrative statements, representing a quality of water
that supports a particular use." 40 C.F.R. section 131.3(b).
As discussed above, the State of Colorado has not developed
a use classification for California Gulch. However, the State
has classified the segment of the Arkansas River from immediately
above California Gulch to Lake Fork for class 1 cold water
aquatic life, secondary contact recreation, and agricultural
uses. The aquatic life classification was discussed earlier.
Section 3.1.13 of The.Basic Standards and Methodologies defines
the other two uses as follows:
1 .
Secondary Contact (Class 2) Recreation
These surface waters are suitable
or intended to become suitable for
recreational uses on or about the
water which are not included in the
primary contact subcategory.
(Primary contact uses include
prolonged and intimate contact with
the body or for recreational
activities when ingestion of small
quantities of water is likely to
occur. )
2.
Agriculture
These waters are suitable or
intended to become suitable for
irrigation of crops usually grown
in Colorado and which are not
hazardous as drinking water for
livestock.
5 Colo. Code Regs. 1002-8.
The State has also identified the "basic standards" portion
of The Basic Standards and Methodologies as an ARAR for the Yak
Tunnel operable unit. See 5 Colo. Code Regs. 1002-8. Section
3.1.11 of these regulations establishes basic standards
applicable to all waters of the State. The key portions of these
standards for the Yak Tunnel operable unit state:
Substances attributable to human-induced
discharges ... shall not be introduced into
waters of the State:
C-8
-------
(a) which can settle to form
bottom deposits detrimental to the
beneficial uses. Deposits are
stream bottom buildup of materials
which include but are not limited
to anaerobic sludges, mine slurry
or tailings, silt, or mud; or
(b) which form floating debris,
scum, or other surface materials
sufficient to harm existing
beneficial uses; or
(c) which produce color, odor, or
other conditions in such a degree
as to create a nuisance or harm
existing beneficial uses or impart
any undesirable taste to
significant edible aquatic species
or to the water; or
(d) in amounts, concentrations, or
combinations which are harmful to
the beneficial uses or toxic to
humans, animals, plants, or aquatic
life; or
(e) in amounts, concentrations, or
combination which produce a
predominance of undesirable aquatic
life; or
(f) in concentrations which cause
a film on the surface or produce a
deposit on shorelines.
,
In addition to these "basic standards," the State of Colora4o has
established numeric standards for the segment of the Arkansas
River between California Gulch and Lake Fork. The State did not
identify these numeric standards as ARARs because, as the State
noted, the current stream standards for the Arkansas River take
into account the pollution from California Gulch and are not
protective of aquatic life.
The basic standards will apply to discharge of treated
effluent from the interim treatment facility component of the
selected remedy. EPA anticipates that the interim treatment
facility will not attain section 3.1.11(d) of the basic
standards.
C-9
-------
D.
Antidegradation Standard
The State of Colorado has also identified its
antidegradation standard as an ARAR tor the Yak Tunnel operable
unit. Section 3.1.8 of The Basic Standards and Methodologies, 5
Colo. Code Regs. 1002-8, provides:
Existing uses shall be maintained as required
by state and federal law. No further water.
quality degradation is allowable which would interfere
with or become injurious to existing uses.
Under section 3.1.3, the antidegradation standard applies to all
waters of the State.
State regulations do not define the term "existing uses".
Under Federal regulations, existing uses are defined as "uses
actually attained in the water body on or after November 28,
1975, whether or not they are included in the water quality
standards." 40 C.F.R. section 131.10.
The selected remedy will meet this requirement and will in
fact substantially reduce the current metals loadings in'
California Gulch.
III.
LOCATION-SPECIFIC REQUIREMENTS
Location-specific requirements set restrictions on
activities depending on the characteristics of a site or its
immediate environs and may thus limit the conduct of activities
in particular locations. The selected remedy includes activities
potentially affecting historical resources, streams, floodplains,
and wetlands. Therefore, the National Historic Preservation Act,
Archeological and Historic Preservation Act, Fish and Wildlife
Coordination Act, Clean Water Act, Executive Order on Floodplain
Management, Federal and State waste management regulations, and
the Executive Order on Protection 'of wetlands establish
requirements which have been identified as ARARs. In the
remedial design phase, EPA will further refine the location and
design of the remedial action components. To the extent that the
remedial action will affect historical resources, streams,'
floodplains, or wetlands, EPA will ensure that all location-
specific requirements are met.
A.
National Historic Preservation Act
The National Historic Preservation Act, 16 U.5.C. section
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
C-IO
-------
Places. According to the Department of the Interior, California
Gulch and the Yak Tunnel lie within the Leadville National
Historic District/National Historic Landmark, and the Yak Tunnel
is significant because of its historical association with mining
engineering in the 19th and 20th centuries. To minimize adverse
effects from implementation of the selected remedy, EPA will
follow the procedures for protection of historic properties 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 63, and 40 C.F.R section 6.301(c).
B.
Archeological and Historic Preservation Act
The Archeological and Historic Preservation Act, 16 U.S.C.
section 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 EPA finds or is notified by an appropriate historical or
archeological authority that its activities may cause irreparable
loss or destruction of significant scientific, prehistorical,
historical, or archeological data, EPA will follow the p~ocedures
set forth in the statute and in 40 C.F.R. section 6.301(c) to
provide for data recovery and preservation activities.
C.
Fish and Wildlife Coordination Act
The Fish and Wildlife Coordination Act, 16 U.S.C. sections
661-666, requires Federal agencies involved in actions that will
result in the control or structural modification of any natural
stream or body of water, for any purpose, to take action to
protect the fish and wildlife resources which may be affe~ted by
the actiqn. The tunnel plugging component of the selected remedy
will modify streamflow and the surface water diversions and
construction of the surge ponds may involve work in or affecting
California Gulch. EPA will therefore consult with the U.S. Fish
and Wildlife Service and the Colorado Department of Natural
Resources to ascertain the means and measures necessary to
mitigate, prevent and compensate for project-related losses of
wildlife resources and to enhance the resources. EPA received
and responded to comments on the FS alternatives and the proposed
plan from both the Department of Interior and the State of
Colorado. In addition, the State has been consulted on the
Record of Decision. During remedial design, EPA"will undertake'
further consultation to meet the requirements of this statute.
D.
Clean Water Act (Section 404)
Section 404 of the Clean Water Act, 33 U.S.C. section 1344,
requires permits 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
C-ll
-------
seas." Under 33 C.F.R. Part 328, "waters of the United Stat~s"
are defined for the purposes of section 404. The definition is
extremely b~oad and covers streamsj including intermittent.
streams. See 33 C.F.R. section 328.3(a). The term "fill
material" includes "any material used for the primary purpose of
replacing an aquatic area with dry land or of changing the bottom
elevation of a water bod~." 33 C.F.R. section 323.2(e). The
"discharge of fill material" means the addition of fill material
into waters of the United States. 33 C.F.R. section 323.2(f).
Activities associated with the selected remedy could trigger
Section 404 requirements. California Gulch falls within the
definition of "waters of the United States." Components of the
selected remedy, including construction of surge ponds, the
surface water diversions, and road construction are likely to
involve some discharge of material into California Gulch. Under
section 121(e) of SARA, no Federal permits are required. In
addition, the selected remedy falls within the definition of
activities covered by the "nationwide permits" regulations.
Under 33 C.F.R. section 330.5, specified activities are
permitted, provided that certain conditions are met. This
provision covers "[s]tructures, work, and discharges for, the
containment and cleanup of oil and hazardous substances which are
subject to the National Oil and Hazardous Substances Pollution
Cont~ngency Plan, (40 CFR Part 300) ...." 33 C;F.R. section
330.5(a)(20).
Even though "the permit application process need not be
followed, both consultation and substantive requirements will be
followed during the remedial design phase. Under 33 C.F.R.
section 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." EPA will consult with the Regional Response
Team during the design phase. Although no permit will be .
obtained, all substantive requirements will be met. These
include substantive conditions set forth in 33 C.F.R. section
330.S(b), the management practices outlined in 33 C.F.R. section
330.6, the requirements governing road construction activities in
33 C.F.R. section 323.4(a)(6), and the section 404(b)(1)
gUidelines set forth in 40 C.F.R. Part 230. In addition, the
policies discussed in 33 C.F.R. section 320.4 will be considered.
E. Executive Order on Floodplain Manaqement
The Executive Order on Floodplain Management, Exec. Order
No. 11,988, requires Federal agencies to evaluate the potential
effects of actions they 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. section
6.302(b) and Appendix A. .In addition, EPA has developed guidance
C-l2
-------
entitl~d "Policy on Floodplains and Wetlands Assessments for
CERCLA Actions," dated August 6, 1985.
Pursuant to regulations and guidance, EPA determined that
remedies considered for the Yak Tunnel operable unit could affect
the 100-year floodplain along California Gulch. Therefore, EPA
identified and evaluated the floodplain as part of the Phase I RI
and considered floodplain issues associated with various
alternatives in the FS. EPA provided for public review of the
floodplain assessment through the public notice and comment
period on the Phase I RI and the FS. Several components of the
selected remedy may affect the floodplain in upper California
Gulch and near the Yak Tunnel. These are the surface water
diversions and possibly construction of the surge ponds. The
Statement of Findings contained in Appendix D of this ROD
documents EPA's decisionmaking regarding floodplains.
F.
Federal and State Waste Management Regulations
Both Federal and State solid and hazardous waste statutes
have requirements pertaining to location of facilities in
floodplain areas. The selected remedy may involve interim
storage and disposal of excavated 50ils and waste treatment plant
sludge. To the extent that the remedy involves storage or
disposal of solid wastes, the Federal and State requirements
govern~ng siting and operation of facilities in the floodplain
will be met. See 40 C.F.R. section 257.3-1 and 6 Colo. Code
Regs. 1007-2, section 4.1.2. Disposal of excavated material
which meets the definition of hazardous waste under 40 C.F.R.
section 261.21-.24 must meet the requirements set forth in 40
C.F.R. section 264.18(b).
G.
Executive Order on Protection of Wetlands
The Executive Order on Protection of Wetlands, Exec. Order
No. 11,990, 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 4"0 C.F.R.
section 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.
EPA has iden~ified potential wetland areas along lower
California Gulch based on a review of aerial photographs. The
potential wetlands are shown in Figure 2-6 of the Phase I RI
report. EPA subsequently conducted a field inspection and
determined that there are areas classified as wetlands. The
decrease in California Gulch surface water flow resulting from
tunnel plugging may reduce flow to these wetlands. Therefore,
EPA has determined that there may be effects on wetlands, and
C-13
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this requirement is an ARAR. The Statement of Findings contained
in Appendix D of this ROD documents EPA's decision-making
regarding wetlands.
IV.
ACTION-SPECIFIC REQUIREMENTS
Performance, design, and other action-specific requirements
set controls or restrict~ons on particular kinds of activities
related to management of hazardous substances, pollutants, or
contaminants. These requirements are triggered not by the
specific chemicals present at a site but rather by the particular
remedial activities that are selected to accomplish a remedy.
This section describes the action-specific requirements for each
component of the selected remedy.
A.
Surge Ponds
Design, construction, and operation of the ponds will be
governed by several sets of requirements. As discussed
previously, several location-specific requirements and the
requirements governing the interim treatment facility wi~l be
ARARs for the surge ponds. In addition, certain requirements
from Federal 'and State waste management regulations are
considered ARARs for the surge ponds. These are described below.
The Federal and State solid waste regulations contain
requirements applicable to the ponds. The Criteria for
Classification of Solid Waste Disposal Facilities and Practies,
40 C.F.R. Part 257, include criteria related to surface water,
ground water, air, and safety which are relevant to design,
construction, and operation of the ponds. See 40 C.F.R. sections
257.3-3, .3-4, .3-7, and .3-8. These provisions are principally
aimed at municipal and industrial solid waste and do not fully
address concerns related to mining waste. See 51 Fed. Reg.
24,496, 24,501 (1986). Regulations promulgated pursuant to the
State Solid Wastes Disposal Sites and Facilities Act, Colo. Rev.
Stat. sections 30-20-101 to -118, provide for more substantial
public health and environmental protection. Specifically,
sections 2.1, 2.2, 4.1, 4.2, 6.2, 6.3, 6.4, 6.5, 6.6, and 6.7 of
6 Colo. Code Regs. 1007-2 are considered ARARs for the ponds.
Provisions of regulations governing hazardous waste are also
ARARs. Under 40 C.F.R. section 261.4(b)(7), solid waste from the
extraction, beneficiation, and processing of ores and minerals is
not considered a hazardous waste. However, under CERCLA,
hazardous waste regulations may be relevant and appropriate under
the circumstances of the release. See Memorandum from Henry L.
Longest II to Waste Management Division Directors regarding
Condsideration of RCRA Requirements in Performing CERCLA
Responses at Mining Waste Sites (Aug. 19, 1986).
C-14
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o
To ensure that the design, construction, and operation of
the ponds are protective of human health and the environment, the
following requirements are considered ARARs for the ponds: 40
C.F.R. sections 264.15 (general inspection requirements),
264.16(a) (personnel training), 264.31 (design and operation of
facility), 264.32 (required equipment), 264.33 (testing and
maintenance of equipment), 264.37 (arrangements with local.
authorities), and 264.51-.56 (contingency plans). In addition to
these general requirements, the requirements for surface
impoundments governing design and operation, monitoring and
inspection, and emergency repairs and contingency plans are also
ARARs. 40 C.F.R. sections 264.221, .226, .227. To the extent
that the State has more stringent requirements associated with
these regulations, the more stringent State requirements would
govern.
B.
Tunnel Plugging
.
EPA and the State identified no ARAR's re:~ted to tunnel
plugging. To ensure protection of public health and the
environment, the plugs must be designed and constructed using
best engineering practices. In addition, EPA will look to
requirements under the Surface Mining Control and. Reclamation
Act, 30 U.S.C. sections 1201-1328, for guidance to see that
activities associated with tunnel plugging are protective.
Specifically, EPA will look to the permanent program performance
standards for underground mining activities set forth in 30
C.F.R. Part 817. These regulations are not ARARs, since they
apply to coal mining activities. However, they are designed to
ensure that underground mining activities are conducted in a
manner which preserves and enhances environmental and other
values. See 30 C.F.R. section 817.2. The performance standards
will be used as appropriate.
C.
Water Control Measures
Location, design, and construction of the surface water
control measures will be governed by the location-specific
requirements discussed above. In addition, as with tunnel
plugging, EPA will look to requirements of the Surface Mining
Control and Reclamation Act for guidance to see that activities
associated with water control measures are protective of public
health and the environment. The regulations set forth in 30
C.F.R. Part 817 will be used as guidance for the water control
measures.
D.
Monitoring
The Colorado Water Well and Pump Installation Contractors
Act discussed previously provides minimum standards for the
location, construction, modification, and abandonment of wells.
The monitoring component of the selected- remedy provides for the
C-lS
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construction of monitoring. wells. Pursuant to section 121(e) of
SARA, a permit is not required for the monitoring wells installed
onsite. For onsite wells, the substantive requirements of the
Water Well and Pump Installation Contractors Regulations, 2 Colo.
Code Regs. 402-2 will be met. . For offsite wells, both
substantive and procedural requirements must be met and permits
will be obtained.
In addition, any investigation-derived wastes must be
handled, treated, and disposed of in compliance with' all
applicable requirements.
E.
Water Collection System
The Colorado Water Well and Pump Installation Contractors
Act, Colo. Rev. Stat. sections 37-91-101 to -112, establishes
requirements relating to the installation, modification, and
repair of pumping equipment. The mine water collection system
will pump water from behind the portal plug. Although a permit
is not required for onsite response actions, all substantive
requirements must be met. Therefore, the collection system will
be designed, installed, and maintained in accordance wit~ the
substantive requirements of 2 Colo. Code Regs. 402-2.
F.
Inte~im Treatment Facility
Under the Clean Water Act and the Colorado Water Quality
Control Act, a permit must be obtained for the discharge of
pollutants from any point source into waters of the United
States. Under section 121(e) of SARA, no federal, state, or
local permits are required for onsite remedial actions selected
and implemented in compliance with section 121. Since the
interim treatment facility and the outfall will be located
entirely onsite, no permit will be obtained. Nevertheless, in
accordance with EPA's "Interim Guidance on Compliance with
Applicable or Relevant and Appropriate Requirements," the
treatment facility will comply with the substantive requirements.
To the extent that State requirements are more stringent than
Federal requirements, the State requirements will govern.
Under the Clean Water Act and the Colorado Water Quality
Control Act, water treatment facilities must meet technology-
based effluent limitations and standards. Technology-based
treatment requirements under section 301(b) of the Clean Water
Act, 33 U.S.C. section 1311, represent the minimum level of
control that must be achieved. See 40 C.F.R. section 12S.3(a).
For the interim treatment facility, these requirements are (1)
the best practicable control technology currently available
("8PT"), (2) for conventional pollutants, the best conventional
pollutant control technology ("BCT"), and (3) for toxic and other
nonconventional pollutants, the best available technology
C-16
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economically achievable ("BAT").
125.3(a)(2).
See 40 C.F.R. section
The application of technology-based treatment requirements
depends on the type of discharge. EPA has promulgated effluent
limitations for particular industrial categories and
subcategories. The Ore Mining and Dressing Point Source Category
. contains provisions applicable to mines that produce copper,
lead, zinc, gold, silver, or molybdenum bearing ores, or any
combination of these ores from open-pit or underground operations
other than placer deposits. 40 C.F.R. section 440.100(a)( 1).
These provisions establish effluent limitations for application
of BPT, BAT, and new source performance standards. 40 C.F.R.
sections 440.102(a), 440.103(a), 440.104(a).
These effluent limitations are not legally "applicable" as
the CERCLA response action is not a mining activity. However,
the effluent limitations were designed to address problems and
situations similar to those of the Yak Tunnel operable unit. The
pollutants are similar to those that would be encountered in
gold, copper, lead, zinc, or silver mines, and the mine water
. . ,
collect~on and treatment system component of tne selected remedy
is similar to a typical mine dewatering operation. These
requirements are therefore considered an ARAR.
Additional substantive requirements for the National.
Pollutant Discharge Elimination System program are set forth in
40 CFR Parts 122 to 125. These regulation~ establish, among
other things, a duty to mitigate, requirements. for proper
operation and maintenance of the treatment system, and provisions
governing bypasses and upsets. See 40 CFR section 122.41(d)-(n).
Also, to ensure compliance with the discharge limitations, the
requirements governing monitoring, recordkeeping, and reporting
must be met. See 40 C.F.R. sections 122.21, 122.41, 122.44 and
122.45, 122.48~nd 40 CFR Part 136. Also, best management
practices programs are to be developed in accordance with 40
C.F.R. section 125.104. In addition, any substantive State
requirements more stringent than the Federal requirements would
also apply.
During the design phase, the interim treatment facility will
be designed to meet the substantive federal requirements of the
Clean Water Act and regulations and any more stringent State
requirements.
G.
Disposal of Sludge and Excavated Soils
During the course of construction and operation of the
selected remedy, waste materials requiring storage or diposal
will be produced. The interim treatment facility will produce
sludges requiring storage or disposal. Also, during construction
C-17
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of the ponds and the surface water diversions, there may be
excavations which produce wastes requiring disposal.
As described in the ROD, EPA anticipates that sludge
generated by the interim treatment facility can be stored in the
surge ponds until a final remedy is developed. For interim
storage, the ARAR's are the same as those discussed above with
respect to the ponds. If sludge g~neration exceeds the pond
storage capacity, two additional options are available. The
ARAR's for these options are described below.
1 .
Processing in an Existing Mill or Consolidation in
an Active Tailings Pond
The ARARs are all Federal and State public health and
environmental requirements appl~cable to the milling operation or
tailings pond. In addition, SARA establishes special
requirements associated with transfer of hazardous substances or
pollutants or contaminants to an offsite facility. Under section
121(d)(3) of SARA, the sludge can be transferred only to offsite
facilities in compliance with all applicable Federal and State
requirements. To ensure protection of public health and the
environment, EPA must determine that the facility is in '
compliance with Federal and State requirements before sludge is
taken either to an offsite or onsite mill or tailings pond.
2 .
Interim Storage and Disposal
In addition to the location-specific requirements discussed
above, provisions of both Federal and State waste management
requirements would be ARARs for interim storage or disposal of
sludge. The Federal Criteria for Classification of Solid Waste
Disposal Facilities and Practices, 40 C.F.R. Part 257,
establishes minimum criteria for surface water, ground water,
air, and safety. 40 C.F.R. sections 257.3-3, .3-4, .3-7, .3-8.
Sections 2.1, 2.2, 4.1, and 4.2 of the State Solid Wastes
Disposal Sites and Facilities Regulations establish further
requirements for waste disposal. 6 Colo. Code Regs. 1007-2. Any
sludge disposal facility will be designed in accordance with both
Federal solid waste requirements and more stringent State
requirements.
Although the sludge would be exempt from regulation as a
hazardous waste under 40 C.F.R. section 261.4(b)(2), some
provisions governing hazardous waste storage and disposal are.
relevant and appropriate. The following provisions are ARARs for
management of the treatment facility sludge: 40 C.F.R.section
264.13(a)(1 )-(2) (general waste analysis), 264.14 (security),
264.15 (general inspection requirements), and 264.31 (design and
operation of facility). In addition, certain provisions
governing landfills would al"so be ARARs: 40 C.F.R. section
264.301 (design and operating requirements), 264.303(a)
C-18
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(monitoring and inspection), and 264.309 (surveying and
recordkeeping).
. There are also two options for disposal of excavated soils.
These can be consolidated with an existing waste pile for
remediation in a subsequent operable unit, provided that the
soils are stabilized to prevent migration of hazardous
substances, pollutants, or contaminants. Specifically, it will
be necessary to control I run-on, run-off, and fugitive dust.
Therefore, 40 C.F.R. sections 264.251(C), (d), and (f) have been
identified as ARAR's for disposal of excavated soil in waste
piles. Any potential ground water impacts will be addressed in a
subsequent operable unit. Excavated soils may also be managed in
the same manner as in the treatment facility sludge.
H.
Operations and Maintenance
ARARs for operations and maintenance are discussed in the
context of the ARARs for specific components of the remedy.
I.
Worker Health and Safety
,
The Occupational Safety. and Health Act, 29 U.S.C. sections
651 to 678, and the Federal Mine Safety and Health Act, 30 U.S.C.
sections 801-962, establish requirements to protect worker health
and s~fety. Under 40 C.F.R. section 300.38, applicable health
and safety requirements apply to all response activities under
the National Contingency Plan. These requirements will apply to
all components of the selected remedy.
C-19
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Appendix D
STATEMENT OF FINDINGS CONCERNING
FLOODPLAINS AND WETLANDS
-------
Appendix D
STATEMENT OF FINDINGS CONCERNING FLOODPLAINS AND WETLANDS
INTRODUCTION
EPA has determined that the selected remedy will be located
in or affect a floodplain or wetlands. Therefore, EPA prepared
this Statement of Findings in accordance with Executive Order
11988 entitled "Floodplain Management" (May 24, 1977), Executive
Order 11990 entitled "Protection of Wetlands" (May 24, 1977), 40
CFR section 6.302 and Appendix A, and EPA's "Policy on
Floodplains and Wetland Assessments for CERCLA Actions" (August
6, 1985).
During the Phase I RI, EPA identified both a floodplain and
wetlands along California Gulch (Figure 2-6, EPA, 1987a). EPA
established an approximate boundary for the 100-year floodplain
using data from a Corps of Engineers study (Corps of Engineers,
1983). The flood hazard boundary determination was made using
"Approximate Study Criteria" as applied by the Federal Emergency
Management Agency. No Flood Insurance Rate Maps or Flood Hazard
Boundary Maps are known to exist for the site. Potential wetland
areas near Stringtown, 2 to 2 1/2 miles below the Yak Tunnel
portal, were identified from aerial photographs. The existence
of wetlands along California Gulch was confirmed by a field
inspection.
WHY THE PROPOSED ACTION MUST BE LOCATED
IN OR AFFECT THE FLOODPLAIN 0R WETLANDS
Several components of the selected remedy must be located in
or will affect the floodplain. Some of the water control
measures, including grouting, shaft sealing, and measures to
prevent surface water infiltration, will be located in the
floodplain. Because certain mine shafts, recharge areas, and
areas of potential seepage are already located in the floodplain,
it is necessary to construct water control measures in the
floodplain for effective control of infiltration and seepage.
The same is true for surge ponds. For the ponds to intercept and
collect surge flows effectively, the ponds must be constructed
near the tunnel portal. This area may lie totally within the
100-year floodplain.
No components of the selected remedy will be located in
wetlands. However, the selected remedy may affect the wetlands
along lower California Gulch. Currently, Yak Tunnel discharge is
a primary source of continuous flow for California Gulch. Tunnel
plugging will substantially reduce the contribution of the tunnel
to surface water flow in California Gulch and will probably
reduce flow to the wetland areas. The precise impacts cannot be
determined until the remedy is implemented.
D-l
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S~GNIFICANT FACTS CONSIDERED IN MAKING
THE DECISION TO LOCATE IN OR AFFECT THE
FLOODPLAIN OR WETLANDS INCLUDING
ALTERNATIVE SITES AND ACTIONS
EPA based it decision on the following considerations.
1. Ground water modeling indicates that the portal plug may
cause ground water to seep to the land surface. Reducing
infiltration to mine workings behind the portal plug will reduce
water levels and will thereby decrease the potential for
uncontrolled seepage of contaminated water. If seepage cannot be
controlled, it will be necessary to operate the pumping and
treatment system. Reducing infiltration will reduce the quantity
of water requiring treatment and the amount of ~ludge generated.
Some of the shafts, drill holes, caved-in mine workings, and
other recharge areas are in the floodplain. No alternative"
sites or locations could effectively reduce infiltration from
these recharge areas. ,
2. Surges are instantaneous, uncontrolled releases of large
volumes of water, sludge, and sediments. It will be necesssary
to construct ponds near the tunnel portal to use gravity drainage
to intercept surge flows. The portal may lie within the 100-year
floodplain. The area near the portal is a narrow valley, which
limits the sites available for pond construction. Because of the
geographical restrictions and t~e-size of the ponds, it will be
necessary to locate them within the 100-year floodplain. It is
infeasible to pipe or pump surge flows to another location as the
peak flows during surges are unpredictable and sludges could clog
the pipes.
3. EPA evaluated alternative remedies and determined that
the selected remedy will best address the Yak Tunnel discharge
and offers the greatest long-term environmental protection,
despite the potential effect on wetlands in California Gulch.
WHETHER THE PROPOSED ACTION CONFORMS TO
"APPLICABLE STATE OR LOCAL FLOODPLAIN
PROTECTION STANDARDS
Discussions with State and Lake County officials indicate
that no flood hazard boundaries exist and no State or local
floodplain protection standards have been established for the
portion of the site where the response" actions will occur.
D-2
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STEPS TAKEN TO DESIGN OR MODIFY
THE PROPOSED ACTION TO MINIMIZE
POTENTIAL HARM TO OR WITHIN THE
FLOODPLAIN OR WETLANDS
To protect the surge ponds, a flood control channel will be
designed and constructed to convey flood flows of up to the 100-
year flood fr~m upper California Gulch around this facility.
This feature will protect the treatment facility from flood
damage up to the 100-year flood and will thus minimize the
potential release of contaminants from the treatment plant to
lower California Gulch and the Arkansas River. Further, the
ponds will be designed to prevent washout by floods up to the
100-year event by including a minimum of 3 feet of freeboard on
the dikes above the 100-year flood level.
Water flow to the wetlands near Stringtown will be reduced
because of the tunnel. plugging. However, at the same time, the
remedy may improve water quality in California Gulch and 'could
thus have beneficial impacts on wetlands. EPA will determine
measures to mitigate impacts on wetlands during the design phase,
and, if necessary, during remedy implementation.
HOW THE PROPOSED ACTION AFFECTS THE
NATURAL OR BENEFICIAL VALUES OF THE
FLOODPLAIN OR WETLANDS
Floodplains provide beneficial values by allowing natural
storage of floodwater, thus protecting downstream natural and
manmade features from flood-related damage. Construction of the
surge ponds in the 100-year floodplain will cause a limited
backwater effect upstream and a limited zone of influence
downstream as higher velocity flows from the restricted channel
in the vicinity of the treatment plant reach the natural
California Gulch channel capacities. The exact limits of these
effects and influences have not been calculated. However, they
are expected to be minimal due to the relatively small siz~ of
the facilities compared to the storage capacity of the
floodplain. These localized effects should not adversely affect
the beneficial value of the floodplain for protecting developed
property or human safety, health, and welfare.
Wetlands provide biological, environmental, and aesthetic
values. Widespread surface distrubance from mining activities
has diminished the natural and beneficial values of the wetlands
along California Gulch. Even so, reduced flow in California
Gulch may further diminish these values.. However, reducing the
metals loads in California Gulch will result in an overall
enhancement of environmental.quality.
D-3
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REFERENCE
u.s. Army Corps of Engineers, Omaha District. California
Gulch Tailings Darns, October 7, 1983. Prepared fur the
EPA--Phase I Inspection Reports. October 1983.
,
D-4
-------
CONTENTS
o'
IV.
V.
I.
Overview
II.
Background on Community Involvement
III. Summary
of Public Comments and Agency Responses
Operable Unit Approach
Remedial Alternative Preferences
Other Potential Technologies
Public Health and Environmental
Assessment
Applicable or Relevant and Appropriate
Requirements .
Costs
Technical Issues in the FS and
Proposed Plan
Public Participation Process
Other Comments
Index to Comments.
Explanation of Differences between the Proposed
Plan and the Selected Remedy
Remaining Concerns
Operable Unit Approach
Endangerment Assessment
Appendix h.
Appendix B.
Listing of Community Relations Activities
Yak Tunnel Feasibility Study Revisions
ii
Page
1-1
11-1
111-1
111-1
111-5
111-11
111-17
!I~-18
III-26
111-31
111-42
111-46
111-48
IV-l
V-I
V:... 1
V-1
-------
I .
OVERVIEW
EPA presented its Proposed Remedial Action Plan (Proposed
Plan) for the Yak Tunnel Operable Unit for public comment
and review on August 18, 1987. In its proposed plan, EPA's
preferred remedial action alternative was to collect and
treat the discharge from the Yak Tunnel. EPA also retained
the option to include a partial plugging component.
During the public comment period and public meeting, the
need to address Yak Tunnel contamination was not questioned,
but EPA's proposed alternative received extensive comment.
Some members of the public supported a remedy that could
provide some local employment and keep the tunnel open for
future mineral resource development. A majority criticized
the proposed remedy because of concerns associated with
permanent rehabilitation of the Yak Tunnel and because the
remedy would include a perpetual treatment operation rather
than a permanent solution to the acid drainage problem. The
costs of operating the treatment facility into perpetuity,
and to what extent the residents may have to eventually bear
those costs, concerned many of the local residents.
,
During the public meeting, ASARCO Incorporated presented an
alternate remedy for consideration. This remedy involved
installation of four plugs in the Yak Tunnel plus an in situ
treatment syst~m for the water stored ~nthe mine workings
behind the portal plug. This treatment system would involve
pumping ground water to the surface, mixing it with lime,
and reinjecting it back into the mine workings.
Based on comments and information received during the public
comment period, EPA re-evaluated and modified its preferred
remedial action alternative. The selected remedy includes
the installation of three plugs within the Yak Tunnel and
.construction of surge ponds to collect any material
dislodged during entry into or construction in the tunnel.
The selected remedy also includes water control measures to
minimize the infiltration of surface water into the mine
workings and tunnel. In addition, the remedy incorporates
measures to control the potential seepage of contaminated
ground water rising behind the portal plug to the land
surface. Highly fractured rock in the vicinity of the
tunnel portal will be grouted and, if necessary, the water
level behind the portal plug will be controlled so that
seepage does not occur. This will be achieved by pumping
water from behind the portal plug until a lower water level
is achieved. Water extracted from behind the plug will be
treated with lime to remove metals and released to the ponds
constructed for surge control during plug installation. The
remedy also includes monitoring, operations and maintenance,
and contingency plans. .
I-I
-------
The selected remedy addresses many of the concerns raised
during the public comment period. Tunnel plugging and water
control m~asures will minimize the amount of water requ~ring
treatment and, hence, offer a more permanent so:ution.
Temporary tunnel rehabilitation will be undertaken only to
the extent necessary for installation of the plugs. Thus,
concerns about worker safety and the costs of tunnel
rehabilitation and maintenance have been addressed. EPA did
not select ASARCQ's proposal for in situ treatment because
of uncertainty about its effectiveness. However, if further
study of this proposal demonstrates its effectiveness,
in situ treatment may be considered.
The following sections of this Responsiveness Summary
describe the background on community involvement in remedy
selection, public comments and corresponding EPA responses,
differences between the proposed plan and the selected
remedy, and remaining concerns.
I-2
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.
2.
3.
II.
BACKGROUND ON CO~~uNITY INVOLVEMENT
EPA began Superfund activities at the site in 1982 and has
since maintained frequent contact with members of the
community. Local officials and a number of community groups
have been involved, including the Lake County Board of
County Commissioners, the City of Leadville, the Lake Co~nty
Environmental Task Force, the Lake County branch of the Soil
Conservation Service, and the Leadville-Lake County Mined
Land Reclamation Group.
Community interest and concern about the California Gulch
site is higt. There has ~~~n much community involvement in
site activities, particularly over the past 2 years. During
the Superfund process to date, EPA has released a Phase I
Remedial Investigation (RI) and a Yak Tunnel Feasibility
Study (FS).
For the Yak Tunnel FS, EPA held a 90-day p~~:.ic comment
period to allow the public to review and cor.:ent on the FS
and the proposed remedial action. This recent activity,
along with previous interviews ana discussi0ns with
community members, has highlighted the following majo~
concerns.
1.
Many members of the ccm:nJ.:1 Lt.! i: ~ i - ; ; . _. , .: ( t,.':': r t.Le
actions of the Federal and Stat~ agenc~es in the a~e~.
Specifically, they are concerned with the cost of the
investigations, that the State and Federal governments
have unnecessarily duplicated efforts, and that the
process aa it relates to Superfund is confusing.
EPA Response. EPA is the lead agency for Superfund
activities at the California Gulch site. EPA and the
State have clarified their roles and responsibilities
at the site. EPA is continuing to inform the public
about the Superfund process.
Many community members are concerned about the
Superfund cost recovery provisions. Residents are
concerned about the potential economic impact of cost
recovery on individuals within Leadville, on the mining
companies, and ultimately on employment in the
community.
EPA Response. The cost recovery provisions are set
forth by statute. EPA will help the community to
understand these provisions. In accordance with the
law, EPA will select cost-effective remedies.
Members of the Lake County
local officials would like
involvement and input into
RIfFS process.
Environmental Task Force and
to have more direct
the technical aspects of the
II-1
-------
6. .
EPA Response. In response to community concern, EPA is
plann~ng opportunities for substantial public
involvement in studies for subsequent operable units.
4 .
Stringtown residents have voiced concern
contamination on their properties. They
is focusing on other aspects of the site
neighborhood.
about the
feel that EPA
and not their
EPA Response. Subsequent operable units will address
environmental and public health issues in Stringtown.
5.
Local residents are concerned about possible adverse
effects of contaminated surface water on the use of the
Arkansas River as a fishery and for irrigation.
EPA Response. The selected remedy for the Yak Tunnel
addresses a major source of contaminants to the
Arkansas River. EPA plans to implement further actions
at the site to reduce the impact of contaminants on the
Arkansas River.
Some community members are concerned with the negative
image associated with the site and its potential ~ffect
on tourism. Community members would like to emphasize
the positive aspects of mining and avoid negative
connotations, particularly inaccurate perceptions of
health problems associated with mining wastes..
EPA Response. EPA appreciates and recugnizes that the
mining legacy of Leadville is a valuable resource. In
t~e long-term, cleanup of the California Gulch site
will protect public health, welfare, and the
environment.
II-2
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III.
SU~.ARY OF PUBLIC COMl-IENTS AND AGENCY RESPONSES
The public comment period was held from July 7 to October 5,
1987, and included a public meeting in Leadville on
September 1, 1987. Comments received during the co~ent
period on the FS and Proposed Plan are summarized below.
The comments are categorized by topic and an index is
provided at the end of this section so that commenters can
locate where their specific comments are addressed. The
topics are: operable unit approach, remedial alternative
preferences, other potential technologies, public health and
environmental assessment, applicable or relevant and
appropriate requirements (ARARs), costs, technical issues in
the FS and Proposed Plan, public participation process, and
other comments.
OPERABLE UNIT APPROACH
v
ASARCO Incorporated (ASARCO), Hecla Mining Company (Hecla),
Leadville Corporation, and Resurrection Mining Company and
Newrnont Mining Corporation (Resurrection) disagreed with
EPA's operable unit approach for the Yak Tunnel. Specific
comments are described below. ,
1.
Resurrection stated that EPA incorrectly defined the
operable unit because, while the Yak "Tunnel discharge
is a discrete component of the site, the Yak Tunnel
itself and the influence of the tunnel on surface water
and ground water regimes throughout the site are not
"discre1:.e."
EPA Response. EPA agrees that "the influence and
relationship of the Yak Tunnel on the overall site is
not discrete and measurable;" i.e., the harm from the
Yak Tunnel is indivisible. However, under the National
Contingency Plan (NCP) , an operable unit is defined as
"a discrete part of the entire response action that
decreases a release, threat of release, or pathway of
exposure" (40 CFR Section 300.6). Thus, an operable
unit is a discrete part of the response action, not a
discrete part of the contamination problem.
2.
ASARCO commented that EPA failed to define the operable
unit specifically, which would assist ASARCO in
evaluating the appropriateness of the operable unit.
EPA Response. EPA relied on the NCP definition of
"operable unit," which encompasses response actions
that decrease a release, threat of release, or pathway
of exposure. In the Phase I RI Report and the FS, EPA
defined and characterized the release and threatened
release of hazardous substances, pollutants, and
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4 .
contaminants from the Yak Tunnel portal into California
Gulch surface waters. In the FS, EPA identified and
evaluated specific response actions that would decrease
this release and threat of release. EPA believes that
further definition of the operable unit is unnecessary
to the evaluation of the operable unit approach or
selection of remedy. .
3 .
ASARCO, Leadville Corporation, and Resurrection
questioned whether the operable unit remedy would be
cost-effective. It was suggested that premature
selection of remedy for the Yak Tunnel operable unit
could unnecessarily complicate or prove
counterproductive to the overall site remedy. These
commenters also stressed the importance of an
integrated approach to the entire site and the
inefficiencies and inconsistencies that could be
associated with an operable unit approach. ASARCO
noted specifically that cleanup standards, goals,
approaches, methodologies, and technologies for the Yak
Tunnel operable unit may be inconsistent with the
remediation ultimately required for the rest of the
site. Each of these commenters suggested that
integration with the full-site remedy would help ensure
that the operable unit response actions were
cost-effect1ve.
. EPA Response. Under Section 300.68(c) (3) of the NCP,
an operable unit may be implemented before selection of
an approp~iate final remedial action, provided that the
operable unit measures are cost-effective and consistent
with a permanent remedy. EPA recognizes the need for
an integrated approach to site remediation. In response
to public comment, EPA has modified the remedy described
in its Proposed Plan to promote integration with
response actions for other portions of the site. The
tunnel plugs and water control measures are part of the
permanent remedy for the site. An interim treatment
facility was selected so that a comprehensive approach
to water treatment at the site may be implemented in a
subsequent operable unit. Given these modifications,
EPA believes that the operable unit will be well
integrated with the full-site remediation.
Hecla suggested integration of remedial action through
synchronization and coordination of operable units,
particularly noting the need for a carefully planned
and executed sequence of remedial actions, with
construction and transportation schedules, and.
logistical plans so that any particular remedial action
does not negatively affect an already completed
remedial action. Hecla also offered specific.
suggestions on how treatment plant location and sludge'
will be temporarily stored in the surge ponds.
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6.
EPA Response. EPA agrees \vi th this comment and will
endeavor to achieve such integration and coordination
with subsequent operable units. The selected remedy
addresses concerns about inconsistencies arising from
treatment plant location, and sludge will be
temporarily stored in the surge ponds. Permanent
sludge disposal options will be addressed in a
subsequent operable unit.
5.
ASARCO and Hecla stated that the NCP requires that
rem~dial actions for an operable unit be consistent
with the final remedy for the entire site. ASARCO
further argued that EPA's alternatives evaluation for
the Yak Tunnel was premature, temporary, and perhaps
incompatible with final remedial measures for the whole
site. This commenter also noted that EPA could predict
the consistency of an operable unit remedy only if EPA
already decided internally what the site-wide remedy
will be. Resurrection asserted that, without knowing
the permanent remedy, it is impossible to select an
operable unit remedy that is consistent with a
permanent remedy.
EPA Response. EPA disagrees with ASARCO's and H~cla's
interpretation of the NCP requirement. The language of
the NCP requires that the operable unit response actions
be "consistent with a permanent remedy." See 40 CFR
Section 300.68(c) (3) ~ The NCP dces not require, as
these commenters assert, that the operable unit be
consistent with the final remedy for the entire site.
EPA has not yet selected a remedy for the entire
California Gulch site, nor is it required to do so by
the NCP before selecting a remedy for this operable
unit. EPA has selected operable unit response actions
that are "consistent with a permanent remedy." By
this, EPA means both that the response actions are
intended to be a part of a full-site remedy and that
they do not foreclose or limit implementation of other
operable units in th~ future.
ASARCO, Hecla, Leadville Corporation, and Resurrection
suggested that the selection of remedy for the Yak
Tunnel is premature. They commented that no remedy can
appropriately be selected for the Yak Tunnel operable
unit until EPA has completed the full-site remedial
invest~gation and selected remedies for the ~ntire
site, including all other sou~ces of contamination.
EPA Response. EPA believes that an operable unit
approach for the Yak Tunnel is appropriate at this
time. The purpose of an operable unit is to allow EPA
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9 .
to take steps to alleviate threats to public health or
welfare cr the environment prior to development or
implementation of a complete remedial action. The Yak
Tunnel releases an estima~ed.210 tons of metals per
year into California Gulch surface water and is a major
source of metals contamination at the site. The
selected remedy will substantially decrease the release
~nd threat of release of hazardous substances,
pollutants, and contaminants from the Yak Tunnel portal
and will have a beneficial effect on surface waters.
~PA sees no benefit to delaying implementation of the
selected remedy. Substantial harm will continue if the
tunnel releases are unabated.
7 .
In a relat~d comment, Hecla suggested that selecting a
treatment remedy for the Yak Tunnel prior to remedy
selection for the remainder of the site could foreclose'
opportunities to integrate treatment plant design and
location and sludge disposal options.
EPA Response. This comment has been addressed through
refinement of the selected remedy. Construction of an
~nterim treatment facility will permit the design and
siting of a comprehensive treatment system in ,
conjunction with a subsequent operable unit. As
discussed above, sl~dge.will be temporarily stored in
the surge ponds so that a permanent disposal option can.
be implemented in conjunction with a future operable
unit.
8 .
ASARCO stated that any rational operable
Yak Tunnel must include upper California
stabilization of tailings ponds in lower
Gulch. .
unit for the
Gulch and
California
EPA Response. In EPA's remedy, a portion of the remedy
will involve response actions in upper California Gulch
to seal surface openings for ground water infiltration
into the Yak Tunnel. In addition, response actions
related to the tailings ponds may be necessary for
construction of surge ponds and treatment facilities
and will be determined during the design phase. The
remainder of upper California Gulch, which includes
widespread surface disturbance and waste piles, and
additional work on tailings ponds will be addressed in
a subsequent operable unit.
ASARCO and Resurrection commented that the operable
unit and the California Gulch site as a whole should be
expanded to include additional source areas throughout
the upper Arkansas River, particularly other nearby
mining areas and the Leadville Drainage Tunnel.
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10.
.
EPA Response. EPA is not persuaded that the scope of
the operable unit should be expanded. It is recognized
that there are numerous other sources of contamination
at the site. However, it is not necessary to address
all sources simultaneously. Many of these sources and
areas are geqgraphically dist~nt from the Yak Tunnel,
hav~ difterent waste characteristics (e.g., waste
piles), and potentially involve distinctly different
remediation technologies. The size and scope of the
site will be determined in subsequent operable units.
The Yak Tunnel operable unit was designed flexibly to
permit integration with future operable units. The
Leadville Drainage Tunnel discharge is being addressed
by the Bureau of Reclamation under the Clean Water Act.
Hecla asserted that preparation of separate RI/FSs for
different parts of the site would be duplicative,
repetitive, needlessly costly, and a waste and misuse
of valuable technical talent.
.
EPA Response. EPA does not believe th~~ preparation of
separate RI/FSs for various operable units need
necessarily be duplicative or repetitive. Subsequent
operable units will gather environmental data no~
previously studied. EPA further believes that
conducting the response action in operable units is '
necessary to address this large and complex site
appropriately.
REMEDIAL ALTERNATIVE PREFERENCES
Numerous parties made comments expressing preferences about
the remedial alternatives developed by EPA and the
alternative identified in the Proposed Plan (Alternative 5).
These are summarized below.
1 .
2 .
Leadvilie Corporation supported Alternative 7 as "viable
and workable" and the "most viable approach," and al~o
noted that Alternative 2 may have merit. Leadville
Corporation also found merit with the employment
opportunities proposed by Alternative 4, but agrees,
with EPA that this alternative is unreliable, likely to
create substantial adverse environmental impacts, and
extremely difficult and expensive to undertake.
EPA Response. EPA acknowledges and appreciates the
comment. EPA has incorporated the tunnel plugging
aspects of Alternative 7 .into the selected remedy.
Alternative 2 is discussed below.
Hecla commented that Alternatives 5 and,7 were
inco~rectly selected as suitable actions because:
(1) the consequences of neither are identified nor
addressed, (2) the alternatives they were compared
1II-5
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against were not properly evaluated, and (3) they do
not fulfill the intent of the operable unit approach.
EPA Response. EPA dis~grees with these contentions.
Alternatives 5 and 7 were developed through a
technology screening, alternative identification, and
initial alternative screening process that meets the
requirements ot Section 121 of SARA, the NCP, and OSWER
Directive 9355.0-19. These two alternatives were
selected for detailed analysis because they best meet
the implementability and effectiveness criteria
presented in Section 7 of the FS. Both alternatives
have the greatest potential to attain the ARARs
established for this operable unit.
3 .
ASARCO provided
11 alternatives
Yak Tunnel FS.
alternatives.
discussion and comments for each of the
developed and evaluated by EPA for the
ASARCO also presented two additional
EPA Response. EPA appreciates ASARCO's comments ~n
response to remedial alternatives developed in the FS.
Careful considera~ion was given to these comments
during selection of the Yak Tunnel remedy.
4 .
ASARCO stated' that neither Alternative 5 nor.
Alternative 7 should have passed the screening process
because (1) it is not feasible to rehabilitate and'
maintain the tunnel, (2) the proposed treatment plant
is flawed, and (3) the perpetual sludge disposal
problem of such treatment was not addressed.
EPA Response. For reasons discussed in the previ~us
response, EPA disagrees with these contentions. Both
Alternative 5 and 7 are technically feasible: tunnel
rehabi~itation can be accomplished using specialty
. contractors and standard mining technologies. The lime
High Density Sludge treatment process is a proven
process and perpetual disposal of sludge was
acknowledged and addressed in Sections 5, 7, and. 8 of
the FS.
5 .
Both ASARCO and Hecla commented that EPA's
Alternative 2 should have passed the screening process
and been carried through detailed analysis. .
EPA Response. EPA conducted the initial screening of
alternatives in compliance with Section 121 of SARA,
the NCP, and OSWER Directive 9355.0-19. Alternative 2,
as defined in the FS, does not meet the criteria for
implementability (questionable reliability in halting
the discharge of acidic water to California Gulch) and
effectiveness (inability to meet.cleanup criteria for
II1-6
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8.
9.
the Yak Tunnel effluent) and was, therefore, dropped
from further consideration in detailed analysis vf
alternatives. Nevertheless, EPA recognizes that
Alternative 2, with modifications to control seepage of
contaminated water, may be an effective remedy. The
selected remedy incorporates elements of Alternative 2.
6 .
Leadville Corporation suggested that if EPA decides to
build the chemical wastewater treatment plant, wetlands
treatment should also be considered as a tertiary
treatment system and an emergency back-up should the
chemical treatment plant fail for some reason.
Leadville Corporation also discussed the possibility of
rehabilitating tailings ponds into wetlands.
EPA Response. EPA has selecteq an interim lime
treatment facility for this operable unit. Wetlands
treatment, which presents potential benefits, will be
evaluated further as part of a comprehensive treatment
alternative during a subsequent operable unit.
7 .
Resurrection stated that partial plugging of the Yak
Tunnel to isolate the Ibex-Irene Group and
Resurrection-Diamond Group of mines should be on~ of
the initial remedial activities under any scenario.
According to Resurrection, partial plugging of the mine
workings, combined with a surface water infiltration
reduction program, is a logical and reasonable first
step in the remediation process.
EPA Response. EPA agrees with this comment. The
selected remedy includes plugging of the Ibex-Irene and
Resurrection Group of workings and a surface water
infiltration reduction program.
Resurrection stated that Alternative 5 is not a
reasonable component of overall site remediation and is
not technically effective or cost-effective.
EPA Response. As discussed in the FS and Proposed
Plan, EPA believes that Alternative 5 would be
effective, implementable, and cost-effective.
However, EPA also believes that the selected remedy
offers greater potential for long-term reduction in
mobility and toxicity of metals. The selected remedy
also offers a flexible approach for integration with
the full-site remedy.
Hecla stated that Alternative 5 has major disadvantages
in that it is not a permanent remedy as it would
require perpetual treatment and it would incorporate
offsite disposal. Hecla further asserted that EPA
disregarded alternatives, such as plugging, which
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11.
12.
potentially represent a permanent solution and do not
require offsite disposal. Hecla also noted th~t
treatment was not a permanent remedy in that the
hazardous substances are not destroyed or neutralized.
EPA Response. EPA evaluated a range of plugging
alternatives in the FS and retained a plugging option
in the Proposed Plan. The selected remedy includes a
plugging component, because plugging offers a greater
potential for a permanent remedy. EPA disagrees with
Hecla's comments concerning offsite disposal; sludge
disposal could Occur onsite. Also, it should be noted
that there is no treatment process to destroy metals
permanently, so the range of permanent treatment
options is relatively limited. Nevertheless, treatment
can reduce the toxicity of metals permanently by
limiting their bioavaflability. The interim treatment
facility will serve this function.
10.
Hecla stated that the preferred alternative has
significant adverse effects and very limited
environmental benefits and that other alternatives,
including plugging and a unified approach to the site,
may have fewer environmental impacts and greater,
environmental benefits.
EPA Response. As discussed above, the selected remedy
incorporates a plugging component and offers a flexible
and unified approach to remediation of the site.
Hecla stated that EPA has failed to establish that the
preferred alternative will be effective in attaining
cleanup goals and standards in perpetuity. Hecla
further stated that the total plugging alternative
would satisfy all ARARs.
EPA Response. As documented in the FS, EPA determined
that Alternatives 5 and 7 offered the best approach to
attainment of cleanup goals for the site. Since the
Yak Tunnel is only one of many sources of metals
contamination at the site, a remedy for the Yak Tunnel
alone is unlikely to result in attainment of chemical-
specific ARARs (see Appendix C of the Record of
Decision). Nevertheless, a significant reduction in
metals loadings can be achieved. EPA disagrees that
total plugging as described in Alternative 2 would
attain ARARs because of the potential for uncontrolled
surface seepage of contaminated water.
Hecla suggested that Alternative 2 could be improved
through postplugging monitoring programs, coupled with
extraction systems, to contain any contaminated
seepage.
III-8
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EPA Response. The selected remedy includes several
components to address the potential for contaminated
seepage. Grouting will be used to minimize and control
seepage. If necessary, water behind the portal plug
will be collected and treated. A monitoring program
will be implemented.
13.
The Department of the Interior commented that if the
tunnel is plugged or partially plugged, a series of
wells to monitor quantity and quality of adjacent
ground water is essential. The Department of Interior
further stated that the selected remedy must require
corrective action by the entity responsible for
plugging, should monitoring indicate potential problems
relating to the Leadville Drainage Tunnel.
EPA Response. The selected remedy includes a monitoring
component to provide for evaluation of localized and
regional ground water and surface water impacts.
Appendix A of the Record of Decision contains the
results of conceptual hydrogeologic modeling to predict
ground water impacts under various scenarios. This
conceptual model indicates that any increase in flow
toward the area drained by Leadville Drainage Tun~el
should be minimal. The modeling will be supplemented
by field measurements, both before and after plugging,
using the monitoring program described in the Record of
Decision. The selected remedy includes implementation
. of contingency measures, if necessary.
14.
Hecla commented that the preferred alternative
described in the Proposed Pl~.n does not represent "a
cost-effective alternative 'that effectively mitigates
and minimizes threats to and provides adequate
protection of public health and welfare and the'
environment" as required by 40 CFR Section 300.68(i).
EPA Response. EPA disagrees with this comment, but has
modified the chosen alternative. The protectiveness
and cost-effectiveness of the selected remedy are
described in Section VI of the Record of Decision.
15.
Hecla commented that EPA failed to establish that the
preferred alternative would be effective in attaining
cleanup goals and standards in perpetuity. .
EPA Response. T~e degree to which the preferred
alternative would attain ARARs is discussed in the
detailed analysis section of the FS. ARARs attainment
with respect to the selected remedy is discussed in
Appendix C of the Record of Decision.
16.
Leadville Mining and Milling Corporation opposes
plugging the Yak ,Tunnel for the following reasons:
III-9
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18.
plug seals may not be effective and it may not be
possible to remedy this by grouting; plugging would
hinder its planned mining operations because plugging
would deny them easy drainage of water and ventilation;
and plugging WOUld impede future mining activity in the
Yak Tunnel area because most of the workings would be
flooded and the tunnel would no longer be available for
access. The company asserts that, consequently, the
nation would be deprived of a strategic metal resource
and the future economic development of L~adville would
be limited.
EPA Response. EPA believes that, with the exception of
the portal plug, locations for tunnel plugs can be
found that will provide effective seals. Problems are
anticipated at the portal plug and these will be dealt
with by grouting and/or pumping and treatment in the
interim treatment plant.
Tunnel plugging will not impede mining activity.
Future drainage and ventilation for mining operations
can be provided by other standard means such as pumps,
compressors, and shafts. Provision of ventilation,
access, and drainage of mine workings are costs at
doing business for underground mining. Because of the
poor condition of the tunnel, additional investments
would be necessary to rely on the tunnel for
ventilation and drainage. In addition, point source
discharges of water must conform to all applicable
environmental laws and regulations.
l7.
Collegiate Peaks Anglers supports the action that will
r~sult in the least polluted discharge into the
Arkansas River from California Gulch and the area it
drains. In comparing Alternative 5 with the ASARCO
Plugging and In Situ Treatment Proposal described
below, the group was concerned with aspects of both.
However, the members favor Alternative 5 because it
would provide treatment that can be visibly monitored.
This is preferable, according to the anglers, to a
treatment that seems to have many hidden unknowns.
EPA Response. EPA acknowledges the comment and agrees
that the selected remedy should result in protection of
the Arkansas River. EPA's revised remedy will provide
protection of the Arkansas River by reducing the
discharge of metals from the Yak Tunnel. ASARCO's
proposal is discussed be~ow.
Alpenglow Excursions supports total plugging because
that alternative keeps the contaminants in the tunnel
and eliminates the need for sludge disposal.
III-I0
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EPA Response. EPA acknowledges the comment and has
revised its remedy to incorporate tunnel plugging.
19.
The Lake County Environmental Task Force expressed
opposition to plugging the tunnel. The Task Force
commented that the Yak Tunnel system is not a closed
one, and that contaminated water would seep through the
cracks, faults, and karst caves in the Leadville
dolomite and into Evans Gulch, the source of Leadville's
drinking water. The Task Force also asked how the
changes in site hydrology would be monitored.
EPA Response. Geohydrologic model studies conducted by
EPA indicate that movement of contaminated water to the
Evans Gulch area will be minimal. To provide further
safeguards, a ground and surface water monitoring
program has been made an integral part of the selected
remedy. Contingency pump-and-treat measures are also
incorporated to deal with problems that may occur.
OTHER POTENTIAL TECHNOLOGIES
In addition to making comments on EPA's proposed alternatives,
many reviewers proposed innovative or alternative mea~s of
taking remedial action at the Yak Tunnel. These proposals
are discussed below.-
1 .
PLUGGING AND IN SITU TREATMENT
Proposal. ASARCO presented its proposal to EPA in
August, at the public meeting on September 1, 1987, and
in its wr~tten comments on the FS and Proposed Plan.
ASARCO proposed a remedial action in which four plugs -
would be set in the Yak Tunnel to stop the discharge of
acidic mine drainage to California Gulch. ASARCO's
plan also calls for installation of a well and pump
station in California Gulch. A conventional deep well
would be sunk into the old workings to a level below.
the Yak Tunnel. Water from the well would be drawn to
the surface, mixed with lime, and reinjected into the
old workings and plugged tunnel. As the lime and water
mixture settle back through the workings, it would'
react with the dissolved metals, and the metal
hydroxides would settle out in the bottom of the
workings. The in situ treatment system would be .
operated until samples taken from the monitoring and
pumping wells show that the entire stored water volume
had been adequately treated.
If the ground water level reaches a point where water
was seeping to the surface or other detrimental effects
were noted, the problem would be controlled by pumping
water out of the mine. This water would be treated and
III-11
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discharged. The remedy also included surge ponds and
surface water diversions.
Several commenters including Collegiate Peaks Anglers,
Hecla, and Leadville Corporation supported further
investigation into ASARCO's proposal. Leadville Mining
and Milling Corporation expressed concern about the
proposal.
EPA Response. EPA has taken several elements of ASARCO's
proposed remedy into account in developing the selected
remedy. The selected remedy includes: (1) surge ponds,
(2) plugging the Yak Tunnel in several locations,
(3) water control measures, (4) monitoring,
(5) installation of a pump and treat system, and
(6) contingency plans. EPA did not select the exact
specifications of remedial components described in
ASARCO's proposal. The design, locations, and
specifications of response actions will be determined
in ~he design phase.
EPA did not adopt ASARCO's in situ lime treatment
system because of concern about the implementability
and effectiveness of this proposal. Due to the,
complexity of the mine workings, there is a significant
possibility that in situ treatment, as proposed, would
not achieve sufficient mixing and would thus.
ineffectively treat water in all areas of the tunnel
and related mine workings. In addition, sludge
generated by the treatment system may seal off flow
paths, causing shortcircuiting of the system and
rendering the treatment ineffective. Consequently, as
water levels rise behind the portal plug, there could
b~ seepage of contaminated water to the ground surface.
EPA disagrees with ASARCO's comment that the proposal
would attain ARARs, both because of the potential for
contaminated seepage and because of the contribution of
other sources to contamination of surface water in
California Gulch and the Arkansas River.
Nevertheless, EPA is willing to explore the in situ
treatment concept further as it may offer potential for
long-term ef=ectiveness. Proceeding with the selected
remedy does not preclude further exploration of this
concept. In fact, it may provide a means of allowing
the in situ treatment system to be tested in the field.
The pump and treatment component could be used to control
seeps while the monitoring program would allow evaluation
of the effectiveness of the in situ treatment.
2.
IN SITU TREATMENT
Proposal. The Lake County Environmental Task Force
presented a proposal for in situ treatment at the
III-12
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public meeting and in written comments to the EPA. The
proposed alternative includes an alkaline injection
system in which sodium carbonate would be injected into
major recharge zones upgradient of areas of acid
formation. By mixing alkaline water with acidic water,
heavy metals would precipitate in the form of
carbonates and seal the exposed pyritic surfaces.
. Monitoring would be required to determine the
frequency, size, and effectiveness of injections. The
proposed plan does not include plugging the tunnel,
which the Task Force believes should be kept open and
maintained for future mining activities. The Task Force
proposed construction of surge protection and short-
term treatment ponds to handle discharge from the
tunnel. Sludge would be pumped back into the tunnel,
and clean water from Leadville Corporation could be
added to treated water to further dilute any metals
remaining after the process. The Task Force also
proposed construction of a pipeline to convey clean
water to the lower reaches of California Gulch or the
Arkansas River.
EPA Response. Maintaining the tunnel and conducting
in situ treatment are not compatible options; so~ form
of contaminated discharge would perpetually leave the
tunnel and placing sludge back into an open tunnel
increases the potential for environmental damage in the
event of a surge. Although the Agency appreciates
these suggestions, EPA believes the proposal does not
meet the criteria for implementability and
effectiveness stated in Section 7 of the'FS.
3 .
CARBON-DIOXIDE TREATMENT
Proposal. TUSCO Incorporated proposed a plan for
stopping acid formation consisting of flooding the
tunnel with a liquid mixture of carbon dioxide and
ammonia to displace the air in the workings. Th~,
tunnel would then be slightly pressurized to force the
carbon dioxide into the cracks and fissures. By
eliminating the oxygen in the mine voids, the
acid-formation processes would be halted. In the,
proposed process, existing mine water is removed and
treated until the water in the mine has become neutral
and metal-free. At this point, the mine would be
plugged and permitted to flood.
EPA Response. EPA appreciates TUSCO's proposed remedy
for the Yak Tunnel. However, in evaluating this remedy
against EPA's criteria for implementability and
effectiveness, the following concerns have been raised:
(1) the solubility of carbon dioxide in water is high
and will produce carbonic acid; (2) the faults,
fractures, v01d space, drill holes and other openings
III-13
~
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6 .
w~ll ~ake it difficult to keep sufficient carbon
dioxide (liquids) ~n the system; ~nd (3) this is an
unproven technology that will require substantial
research and development pr~or to use at a Superfund
site. .
4 .
BACTERIA TREATMENT
Proposal. TUSCO also commented that recent developments
have been promising in handling the thiobacillus
ferooxidan bacterium. TUSCO suggested that EPA look
into these developm~nts and requested time to present
information to the Agency.
EPA Response. EPA acknowledges that there are emerging
technologies for treating the bacteria that enhances
the generation of acidic water. Some of these
technologies were evaluated in Sect~on 5 of the FS.
However, since EPA has revised its proposed remedy to
include tunnel plugging, bacteria treatment is not
necessary to provide protection of public health and
the environment. EPA would be willing to meet with
TUSCO to discuss bacteria treatment for possible
consideration in subsequent operable units.
,
5 .
POLYMER INJECTION
Proposal. The Department of the Interior noted that
EPA considered only conventional methodologies in its
FS for minimizing recharge to the underground workings.
The Department suggested that innovative technologies,
such as injection of polymers or other cohesive agents
to seal fractures and flow paths, be considered as
well.
EPA Response. These types of sealants were considered -
in various grouting alternatives analyses. These.
actions involve extensive drilling and injection of
material to reach the numerous voids and fractures.
These actions would thus create significant adverse
environmental impacts and be very costly. The use of
polymers or sealing agents will be retained for
consideration during the remedial design of the water
control measures.
ELECTROCOAGULATION
Proposal. The Acid Mine Drainage Action Group (AMDAG)
proposed the use of electrocoagulation as an innovative
technology for treating acid drainage. Acid drainage
would be treated with this process without any other
pre- or posttreatment such as pH adjustment or
filtration. According to AMDAG, initial test work
indicates that the generated sludge may be nonhazardous.
III-14
~
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EPA Response. EPA has modified its proposed remedy to
include ~unnel plugging, which will minimize the amount
of effluent requiring treatment. EPA has selected a
lime treatment system for interim treatment. However,
EPA is interested in obtaining adaitional information
on this emerging technology so that it could be further
evaluated during a subsequent operable unit. AMDAG
presented initial test work data for this process, but
EPA also needs process design, operation, maintenance,
and cost intormation for further evaluation of the
proposal.
7 .
RESTORATION OF THE YAK TUNNEL
Proposal. Leadville Mining and Milling Corporation
proposed that the Yak Tunnel be kept open for the
drainage and ventilation purpo~es for which it was
designed. The company's tunnel plan, as a cost-saving
measure, would require restoration to an opening of
6 feet by 8 feet, room enough for a small haulage
lQcomotive necessary to conduct future maintenance or
repair. The company estimates that some of the worst
areas in the tunnel could incur direct costs of
approximately $1,000 per foot for rehabilitation~
,However, work in most of the tunnel would not be this
expensive. The proposal includes installing track and
a suitable flume under the track to convey water out of
the tunnel. Laterals from the tunnel that are not in
. use would be sealed with concrete walls that had
removable doors in case future access or ventilation is
needed.
EPA Response. Conceptually, many of these suggestions
are implicit in Alternatives 5 and 7. EPA has selected
tunnel plugging as its revised remedy because it will
reduce the amount of acid drainage needing treatment.
Flooding the sulfide zone through tunnel plugging will
reduce the production of acid mine drainage.
8 .
REPLACE TUNNEL
Proposal. Robert L. Elder and other Leadville'
residents suggested that it may be more cost-effective
to construct a new tunnel rather than rehabilitate the
existing Yak Tunnel.
EPA Response. Construction of a new tunnel would raise
the same concerns about cost and safety as Alternative 5,
but would have greater environmental impact.
Construction of a new tunnel would simply perpetuate
the production of acid mine drainage. The selected
'remedy includes tunnel plugging to halt the drainage.
III-15
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10.
9 .
SEEPAGE CONTROL
Proposal. Hecla proposed a variation on Alternative 2
that would include seepage control measures as an
alternative to a permanent treatment plant. This
proposal would include a monitoring program to detect
surface seepage and a sealing/grouting program to abate
seeps. In addition, seeps could be collected,
extracted, and reinjected into the mine workings. If
seepage to the California Gulch alluv~um is determined
to be a problem, a system of extraction wells and/or
ditches could be used to ~ntercept the seepage and pump
it back into the mine workings.
BPA Response. The remedy selected by EPA incorporates
most of the concepts proposed by Hecla. The primary
difference is that the selected remedy will treat and
discharge problem seepages while Hecla proposed that
seepages be collected and reinjected into the
underground workings.
EPA selected the treat-and-discharge option because it
provides for a direct and positive control on ground
water levels (and seeps) in the area behind the ~ortal
plug. If water is reinjected behind the portal plug,
there may be no net reduction in water levels and
seepage would continue. On the other hand, reinjection
of the water behind th~ Ibex-Irene or the Resurrection
plug may be more appropriate provided it does not lead
to unacceptable levels of contaminated seepage from
these workings to the neighboring regional ground water
bodies such as the area around Elkhorn Shaft,
Leadville's water supply. EPA recognizes that this
reinject~on concept has merit and will consider it
further during the design phase of the selected remedy.
PUMPING AND TREATMENT
Proposal. ASARCO identified an alternative that would
include tunnel plugging, collection by pumping and
treatment, and discharge. ASARCO noted that relatively
simple and inexpensive pumping wells could be completed
in the old workings and then used to control water
levels in the tunnel and to remove water at the desired
rate. ASARCO also noted that 'water control by pumping
is presently being practiced successfully at the
Leadville Drainage Tunnel.
EPA Response. These concepts have been incorporated in
the selected remedy. One difference is that the
selected remedy incorporates a shaft or an extraction
well for pumping water from behind the portal plug
instead of the wells suggested by ASARCO. Theshatt
I1I-16
~
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could serve a dual purpose since it could provide a~
easy and sate access for construction of the portal
plug and also be used for pumping. However, EPA agrees
that the ASARCO suggestions have merit and will
continue to investigate the pump well installation
alternative durir.g the design phase of the selected
remedy.
Proposal. Leadville Corporation also proposed a
pump-and-treatment system as part of its remedy. This
proposal includes pumping of water from behind the
Resurrection plug, treatment, and discharge to Big
Evans Gulch while mining operations continue. When
mining ceases, Leadville Corporation would allow water
to rise behind the plug.
.
EPA Response. EPA has not selected this component of
Leadville Corporat~on's remedy as part of the selected
remedy. EPA does not anticipate that it will be
necessary to pump and treat water from =ehind the
Resurrection plug. If monitoring indic~~es that
adverse impacts on ground water may occur as a result
of the remedy, pumping and treatment may be implemented
as a contingency, if appropriate. Although pumpipg and
treatment is not part of the remedy, Leadville
Corporation may on its own initiative pump and treat in
accordance with all applicable regulations as part of
its mining operations.
11.
INTERIM TREATMENT
Proposal. Hecla proposed that EPA consider plugging as
proposed by ASARCO, in conjunction with an ~nterim
treatment system reduced in scope to include basic lime
addition and a settling pond followed by discharge to
the diversion channel. .
EPA Response.
remedy.
This proposal is similar to the selected
PUBLIC HEALTH AND ENVIRONMENTAL
ASSESSMENT
EPA received extensive critical comment from ASARCO, Hecla,
and Resurrection regarding the "Public Health and
Environmental Assessment" section of the FS. These comments
are summarized below.
1 .
Hecla commented that EPA failed to perform an
endangerment assessment sufficient to support its
preferred alternative as required by EPA guidance.
Resurrection also noted that an endangerment assessment
was not performed.
111-17
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EPA Resconse. Under EPA's "Guidance on Feasibility
Studies Under CERCLA," dated June 1985, an FS is to.
include a discussion of the nature and extent of
problems at a site, including the types of releases,
af~ected media, movement of contamination, and
exposures. The "Public Health and Environmental
Assessment" section of the FS serves this function. An
"Endangerment Assessment" is prepared to support an
action under Section 106 of CERCLA, but is not
necessarily part of an FS.. On page 1-6 of EPA's
"Guidance on Feasibility Studies Under CERCLA," it is
noted that an Endangerment Assessment can be. performed
at any point in the RI/FS process, including after the
FS is complete.
.,
....
There were numerous comments critical of the overall
approach and of specific aspects of the "Public Health
and Environmental Assessment."
EPA Response. As outlined in the Record of Decision,
the Yak Tunnel discharges more than 200 tons of metals
per yea~ that contribute to contamination of surface
water, ground water, and sediments. EPA has sufficient
basis to select a Yak Tunnel operable unit remedy\to
abate this release. In conjunction with future
operable units, EPA plans to prepare an Endangerment
Assessment in accordance with all applicable guidance
that will address the threats to puhlic health and
welfare and the environment associated with the entire
site. EPA anticipates that this Endangerment
Assessment will address the majority of concerns raised
by commenters.
3 .
ASARCO provided information and data on aquatic life
and aquatic habitat in the upper Arkansas River to
support its comment that re-establishment and
maintenance of a productive trout fishery should be the
cleanup goal for the Arkansas River.
EPA Response. EPA will carefully evaluate this
information and data, as well as information from
sources, in preparing the Endangerment Assessment
in subsequent operable unit studies.
other
and
APPLICABLE OR RELEVANT AND
APPROPRIATE REQUIREMENTS
ASARCO, Hecla, Leadville Corporation, Resurrection and
others raised comments and concerns about the degree of
III-18
~.
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Appendix C of the Reccrd of Decisicn contains more detailed
information on ARARs.
2 .
3 .
1 .
ASARCO stated that EPA did not comply with EPA's "Interim
Guidance on Compliance with Applicable or Relevant and
Appropriate Requirements," which appeared in the
August 27, 1987, Federal Register, with respect to the
timing of identification and consideration of ARARs.
EPA Response. The Phase I RI report and the FS were
released, respectively, in May and June 1987, before
EPA issued the interim ARARs guidance. Nevertheless,
EPA considered ARARs during both the remedial
investigation and feasibility study. The Phase I RI
contains a discussion of maximum contaminant levels
(MCLs) and ambient water quality criteria (AWQC) and
includes tables comparing MCLs and AWQC to site
sampling data. In the FS, EPA identified a range of
alternatives and screened them based on factors
including their anticipated attainment of ARARs.
Two commenters discussed cleanup goals. Hecla
questioned what the cleanup goals for the Arkansas
River are (e.g., restoration to premining condit~on or
achieving highest quality and practicably attainable
use). Hecla also stated that EPA's cleanup standards
are unsupported because they have no direct relevance
to the ultimate cleanup goals for the Arkar.sas River.
ASARCO stated that the ARARs should be those that allow
the Arkansas to achieve itz highest designated use
classification. .
EPA Response. Under Section 121 of SARA, EPA must
select remedies that assure protection of human health
and the environment. To the ex~ent that hazardous
substances, pollutants, or contaminants will remain
onsite, the remedy must attain a level or stanuard of
control that at least attains federal and state ARARs.
EPA and the State have identified chemical-specific
ARARs as discussed in Appendix C of the FS and
Appendix C of the Record of Decis~on. These ARARs
include State water quality standards designating uses
of the Arkansas River for Class 1 cold water aquatic
life, secondary contact recreation, and agricultural
uses.
Two commenters questioned whether it was appropr~ate to
establish ARARs for an operable unit. Resurrection
asserted that interaction between surface water and
ground water, combined with the commingling of
contaminants from man-made and natural sources
III-19
~
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precludes the establishment of ARARs for the operable
unit. Hecla stated that it is inappropriate to set
discharge limitations for the treatment facility in the
absence of a complete site cleanup program since the
ultimate effect of other sources on water quality in
the Arkansas is unknown.
EPA Response. Under Section 121 of SARA, ARARs must be
established for remedial actions. This requirement
applies, even if the response action is being conducted
in operable units. Interactions between surface water
and ground water and the nature and extent of
contamination may influence which. requirements are
considered ARARs, but ARARs must still be established.
The selected remedy includes an interim treatment
facility for which technology-based effluent
limitations are an action-specific ARAR. This operable
unit is designed to address a major source ut
contamination identified in the Phase I RI. The
effluent limitations will be re-evaluated when a more
comprehensive treatment alternative is developed in a
subsequent operable unit.
4.
ASARCO commented that EPA failed to consider the ~se uf
"alternate contaminant levels" as cleanup standards
pursuant to Section 9621(d) (2) (B) (ii) of CERCLA as
required by EPA's "Interim Guidance on Compliance with
Applicable or Relevant and Appropriate Requirements."
EPA Response. EPA assumes that ASARCO referred to
"alternate concentration limits" as discussed in the
CERCLA provision cited. This provision refers to
alternate concentration limits for hazardous
constituents in ground water under the Solid Waste
" Disposal Act. Since the Yak Tunnel operable unit is
not designed as a ground water cleanup measure, EPA
views this provision as neither applicable nor r~levant
and appropriate. .
5 .
ASARCO, Hecla, and Leadville Corporation expressed
concern that the cleanup criteria did not fully
consider site-specific conditions in the Leadville
area. ASARCO noted that pursuant ~o EPA's "Interim
Guidance on Compliance with Applicable or Relevant and
Appropriate Requirements," ARARs identification depends
on the specific chemicals at the site, the particular
remedial actions, and site characteristics.
EPA Response. Under the interim ARARs guidance,
requirements may be relevant and appropriate if they
address problems or situations sufficiently similar to
those encountered at a CERCLA site that their use is
well suited to the particular site. This can be
III-20
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determined by comparing the characteristics of the
remedial act~on, the hazardous substances in ques~ion,
or the physical circumstances of the site. EPA and the
State identified ARARs for the specific remedial
actions considered for this operable unit. The ARARs
relate to cleanup of metals in contaminated media
addressed by this operable unit. EPA and the State
took into account the physical characteristics of the
site, including surface water and ground water
interac~ion and the location of wetlands and
floodplains, and historic resources.
6 .
ASARCO stated that it cannot determine the relevance or
appropriateness of MCLs as an ARAR until the boundaries
of the operable unit are defined, the points of exposure
outside the boundary are defined, and the point of
compliance is identified.
EPA Response. The rationale for identifying MCLs as an
ARAR for surface water is described in Appendix C. The
pathways of exposure to metals discharged from the Yak
Tunnel are described in Section III of the Record of
Decision. EPA does not believe that it is necessary to
define the "boundaries" of the operable unit, as.n
operable unit consists of response actions. Figures 5
and 6 in the Record of Decision show the proposed
locations of components of the selected remedy.
Section 121 of SARA does not provide fo~ a "point of
. compliance" for ARARs, so MCLs are considered ambient
standards in surface water.
~
I .
ASARCO asserted that EPA ignored the use of
institutional controls in preventing use of ground
water for drinking water downgradient from the Yak
Tunnel.
EPA Response. Institutional controls were evaluated as
Alternative 10 in the FS.
8 .
ASARCO stated that the AWQC are not relevant and
appropriate as they would dictate cleanup in excess of
background levels. Leadville Corporation commerited
that both MCLs and AWQC may not be relevant or
appropriate or even attainable given the potential for
h~gher background levels of metals in mineralized
areas. Hecla and Resurrection were also concerned
about background levels, as were citizens at the public
meeting in Leadville.
EPA Response. Under Section 121(d) (2) (A) of SARA,
remedial actions must require a level or standard of
control that at least attains AWQC where such
requirements are relevant and appropriate under the
III-21
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10.
circumstances of thE: release. Section 121 (d) (2) (B) (i)
describes the factors that EPA must consider in
determining whether AWQC are relevant and appropriate.
This determination is described in Appendix C of the
Record ot Decision. EPA has found no data documenting
premining metals concentrations in California Gulch or
the Arkansas River. Since EPA has no data documenting
premining water quality, EPA could not conclude that
the AWQC would require cleanup in excess of background
levels. EPA recognizes that nonpoint sources of
metals, some ot which may be naturally occurring, may
influence .whether or not cleanup goals can be reached.
9.
ASARCO presented geochemical modeling and information
on the Red Dog ore deposit in Alaska and suggested that
premining water quality was in excess of certain MCLs
and AWQC. At the public meeting, Mr. Will Beach also
noted a comparison between the Red Dog deposit and the
Leadville Mining District and asked if Red Dog were a
Superfund site.
EPA Response. EPA recognizes that surface and ground
water quality in certain mineralized areas does not
meet MCLs and AWQC even though no land disturban~e has
occurred. The area around the Red Dog deposit ~s one
example. Red Dog has not been designated as a
Superfupd site. Under Section 104(c) (3) (A) of SARA,
EPA cannct rernediate.a release or threat of release of
a naturally occurring substance in its unaltered form,
or altered solely through naturally occurring processes
or phenomena, unless a public health or environmental
emergency exists that will not otherwise be addressed
in a timely manner. The California Gulch site can be
distinguished from Red Dog in that the Leadville area
has been extensively altered by mining and minerals
processing activities for more than 125 years.
Nevertheless, EPA recognizes that establishment of
cleanup levels in mineralized areas poses special
challenges. For this reason, EPA is currently studying
this issue and plans to solicit input from the public.
ASARCO performed equilibrium geochemical calculations
to demonstrate that premining surface and ground water
quality contained elevated metal concentrations.
EPA Response. EPA qCknowledges the geochmical modeling
performed by ASARCO. However, the equilibrium
geochemical calculations performed by ASARCO are
inappropriate for determining premining background
levels. The "total" natural system is very seldom in
equilibrium and the watE:r quality is a function cf
complex time dependent reactions and the various types
III-22.
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11.
12.
13.
of rock and soil that the water may encountered. The
metal values predicted by ASARCO could at best only be
used to indicate upper limits for a few localized
pockets of slow moving ground water.
Hecla asserts that EPA advocates adoption of aquatic
life standards to restore or maintain fish population
in California Gulch without any evidence that fish
survived there under premining conditions.
EPA Response. The AWQC are established to protect
freshwater aquatic life, not just fish. EPA plans
conduct a use attainability analysis of California
in a future operable unit to determine what uses,
including aquatic habitat, may be appropriate for
California Gulch.
to
Gulch
ASARCO commented that the State's "basic standards" are
not applicable as cleanup standards below background
levels or to that portion of existing ~~tals levels in
environmental media that is attributab_. to natural
background.
EPA Response. Under Section 3.1.11 of the Basic,
Standards and Methologies, the State's "basic
standards" apply to 1ntroduction of "substances
attributable to human-induced discharges" to waters
the State (5 CCR 1002-8). These standards are not
limited by background levels.
ASARCO and Leadville Corporation questioned whether
aquatic water quality criteria are appropriate cleanup
standards since aquatic species can adapt to higher
concentrations of metals. ASARCO stated State water,
quality standards reflect local acclimation of trout to
metals. -
of
EPA Response. State water quality standards that
retlect an acclimation factor are not necessarily more
appropriate than Federal water quality criteria.
First, both the Federal and State water quality
criteria/standards take into account, to some degree,
the tact 'that acclimation may influence tolerance of
aquatic organisms to some metals. Second, several
factors normally influence tolerance of aquatic
organism~ to metals, so the fact that some species may
be more tolerant to a few metals because of prior
acclimation should not be overemphasized. Third, prior
acclimation has been reported to influence tolerance to
a few metals but acclimation may have no influence on
tolerance to several metals co~on in the California
Gulch and Arkansas River. Finally, State standards in
some segments of the Arkansas River are more stringent
than the Federal criteria, not less stringent.
III-~3
...
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15.
16.
~
14.
ASARCO suggested that cleanup of the Yak Tunnel
discharge could result in fish kills r~sulting fro~
exposure of nonacclimated f1sh to periodic runoff from
other highly mineralized areas.
EPA Response. Aquatic ecosystems are dynamic systems
that ar~ 1nfluenced by a multitud~ of factors. The
removal of one source of metals, even though it is
considered a principal source, is not likely to present
an abrupt shock factor because of residual metals in
sediments and other media. There are also several
other sources of metals in the area that would reduce
the likelihood of development of a nonacclimated
segment of the fish population. Prior acclimation may
influence the tolerance to only a few metals in the
system, not to all. Fish will generally move out of a
particular stream section if the environmental
conditions are outside of their preference ranges.
ASARCO suggested that AWQC are significantly more
stringent than necessary to re-establish and protect
aquatic life in the Arkansas River downstream from the
confluence with California Gulch and are thereby
overprotective. ASARCO further noted that the AWQC
will be more stringent than necessary because they are
calculated to protect 95 percent of freshwater aquatic
species from toxic effects. .
EPA Response. EPA disagrees with this comment. As
discussed Qbove, EPA identified the AWQC as an ARAR in
accordance with statutory requirements. Nevertheless,
EPA plans to undertake further work during future RI/FS
activities to determine whether or not it would be
appropriate to refine this ARAR in subsequent operable
units. EPA disagrees that AWQC are more stringent than
necessary in terms of the percent of species that the
standards are designed to protect. Aquatic species
exhibit a wide range of susceptibility to toxicity and
it is appropriate to protect s~nsitive species.
ASARCO commented that the AWQC are highly influenced by
data for species more sensitive than the brown trout
and benthic macroinvertebrate commun1ties which are
found in streams with elevated metals concentrations.
EPA Response. The AWQC, in general, are not highly
influenced by data for species more sensitive than the
brown trout and local benthic macroinvertebrate
communities. In most cases, the AWQC are based on data
from a range of species, including tish, benthic
macroinvertebrates, and plants. Also, the criteria are
based on a large data set whenever appropriate data are
available.
III-24
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17.
18.
ASARCO stated that it is impossible to establish
numerical cleanup goals to protect fisheries because of
limited data on metals toxicity in resident species.
ASARCO also noted that there is insufficient data on
acute and chronic toxicity to resident species to
recalculate the water quality criteria on a site
specific basis.
EPA Response. The data bases available to and used by
the scientists who established the Federal AWQC and
State standards are not any less appropriate for the
Arkansas River than for many other site-specific
locations. The scientific community, as a rule, would
like site-specific data whenever possible to use as a
basis for making decisions. However, it is certainly
possible and acceptable to make decisions using the
best set of ~vailable data. EPA and th~ State of
Colorado may consider additional site-specific studies
to refine cleanup goals.
~SARCO commented that cleanup criteria should be based
on dissolved metals concentrations and that there is no
good reason to use the total recoverable or acid soluble
analytical methods upon which the AWQC ~re based.,
EPA Response. Metals of concern at the California
'Gulch S~t= may exist in a variety of forms, and
definitive information on the relative toxicities of
the different forms is not always available.
Therefore, no single available analytical procedure is
known to accurately reflect toxicity for a range of
species under varying environmental conditions. The
AWQC were formerly expressed in terms of total
recoverable metals (EPA Water Quality Criteria 1980 and
1986), but more recently, EPA has based the AWQC on the
acid soluble analytical method. The advantages of
using the acid soluble analytical method are presented
in more recent water quality criteria documents (for
example, lead and cadmium AWQC documents, 1984). The
total recoverable measurement is probably too rigorous
in some situations because it may measure some forms of
metals, such as lead occluded in minerals and clays,
that are not toxic and are not likely to become toxic
under natural conditions. On the other hand, dissolved
metals concentrations may exclude some forms of metals,
such as carbonate and hydroxide precipitates, that
could be toxic or become toxic under natural
conditions. At the California Gulch site, there could
be a significant portion of the toxic or potentially
toxic forms of some metals that would be removed during
the tield collection of a sample to be analyzed for
dissolved metals. Therefore, the dissolved metals
procedure could underestimate the toxicity of the
aquatic system.
111-25
~
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20.
21.
19.
Hecla questioned what habitat limitations might prevent
the Arkansas River from achieving its highest qu~lity
and practicably attainable use.
EPA Response. In its comments on the FSand proposed
remedial action plan, ASARCO presented information on
the physical habitat for trout of the Arkansas R~ver
downstream from California Gulch and concluded that
habitat quality is mixed, but that some areas appear to
be good to very good. EPA plans to undertake further
assessm~nt of aquatic habitat in subsequent operable
units.
ASARCO recommended that the re-establishment and
maintenance of a productive trout fishery should be the
cleanup goal. ASARCO proposed, as an alternative to
numer~cal cleanup standards, a .biologically-based
approach to re-establish and maintain water quality
that supports a productive trout fish~ry. ASARCO
suggested using a trout habitat evaluation model to
define the carrying capacity for various river
segments. This model could be used to derive trout
population goals for the various segments. Cleanup of
sources would be phased to achieve a predetermined
degree of cleanup, with elimination of sources of the
metals and use of the most cost-effective metals
removal strategies first. The success of the cleanup
would be measured both by biomcnitoring and by annual
population estimates. Once the acceptable trout
population levels were reached, strea~m standards could
be established and used for compliance monitoring.
EPA Response. EPA agrees with the concept of a
biological approach to measure the success of cleanup
measures. Under Section 121(d) of SARA, remedial
actions must assure protection of human health and the
environment. EPA plans to use biomonitoring and'
biological sampling as part of the remedial action in
subsequent operable units to ensure that the remedial
action is protective. EPA does not view this as a
substitute for numerical cleanup goals that are
necessary for design and implementation of remedies.
There was little public comment on location-specific or
action-specific ARARs. Two cornmenters--the Department
of the Interior and the Colorado Historical Society--
emphasized the historical significance of the Yak Tunnel.
EPA Response. As discussed in Appendix C of the Record
of Decision, the requirements of the National Historic
Preservation Act will be followed.
COSTS
1. Alpenglow Excursions and Mr. Ed Moats
questioned how the cost estimates for
considered, particularly the proposed
derived.
of Leadville
the alternatives
alternative, were
III-26
,.
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EPA Response. CERCLA, the NCP, and EPA's "Guidance on
FeasiLility Studies Under CERCLA," dated June 1985,
descr~be how cost erit~mates are to be developed. These
estimates include both capital costs and costs for.
operations and ma~ntenance for the entire period during
which such activities will be required. In accordance
with EPA guidance, costs are estimated based on vendor
estimates, estimates for similar projects, and standard
costing guidance. The cost estimates for alternatives
for the Yak Tunnel operable unit are referenced in the
cost appendixes of the FS. The Yak Tunnel
rehabilitation cost estimates were based on time and
material estimates and .experience in mines in Canada
and the western United States. The cost estimate for
the selected remedy is set forth in Appendix B of the
Record of Decision.
2 .
Alpenglow Excursions, Mr. Moats, and Mr. Frank Paden of
Leadville questioned how costs could be estimated for a
remedi~l action that would include operations and
maintenance "in perpetuity." These concerns ranged
from incredulity at the timeframe being considered to
confusion about how costs could be estimated into an
endless future. The Department of the Interior and
Hecla also questioned whether the long-term costs
associated with treatment in perpetuity had been
adequately considered.
. EPA Response. "In perpetuity" means forever. However,
because the remedy would leave contaminants onsite, EPA
must review the remedial measures no less often than
each 5 years. Thus, EPA could implement a new
technology at some future date to minimize or eliminate
the need for perpetual treatment. perpetual costs were
calculated through the use of a present-worth analysis.
Under EPA guidance, this type of analysis is used to
evaluate expenditures that occur over different time
periods by discounting all future costs to a common
base year, usually the present. To conduct the
analysis, assumptions must be made about the discount
rate and the period of performance. The period of
performance for perpetual tunnel maintenance and
treatment is infinity. Through use of appropriate
mathematical equations, the present value of
performance into infinity can be calculated. It must
be recognized, however, that this value is not the
total cost of the alternative.
3 .
Alpenglow Excursions, the Lake County Environmental
Task Force, Mr. Carvel Stout, Mr. Robert Dechant, Hecla,
the State of Colorado, and AMDAG questioned details on
cost and time estimates for rehabilitating the Yak
Tunnel.
III-27
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6 .
EPA Response. Cost estimates for tunnel rehabilitation
were made pased on professional judgment by engineers
experienced in tunneling and in tunnel rehabilitation.
Data on the tunnel conditions provided by ASARCO were
used as the basis for the cost estimates. Based on
current knowledge of the tunnel, it was estimated that
more than 8,000 feet would require ti~~er or steel set
rehabilitation. In addition, a 20 percent contingency
factor was included to allow for rehabilitation of
junctions with laterals.
4 .
Alpenglow Excursions suggested that there may be
extensive cost and schedule overruns.
EPA Response. EPA shares this concern about cost and
schedule overruns and will work to ensure that remedial
action is both expeditious and cost-effective. Prior
to and during remedial design, the project schedule and
cost estimates will be reviewed and revised, if
appropr~ate.
5 .
Mr. Dechant, Mr. Stout, Hecla, and the Department of
the Interior commented that the cost estimates for
Alternatives 5 and 7 were too low, particularly ior
operation and maintenance for water treatment
(Alternative 5) costs, capital, operations and
maintenance for plugg~ng/treatment (Alternative 7), and
sludge disposal. The Department of the Interior
suggested further evaluation of recharge reduction
options to reduce the long-term costs of treatment and
sludge disposal.
EPA Response. The cost estimates were developed in
accordance with EPA guidance using the best available
information. Further refinement of cost estimates may
occur during remedial design. The selected remedy
incorporates tunnel plugging, seepage control, and
water control measures to minimize the need for water
treatment and sludge disposal. During the design
phase, a more detailed evaluation of the water control
aspects will be completed.
Mr. E. H. Queener of Leadville asked if the consumer
would help pay for the cleanup.
EPA Response. As described in the Record ot Decision,
EPA has filed an action against parties responsible for
site contamination, including the Yak Tunnel discharge.
EPA is seeking to have responsible parties undertake
and bear the costs of cleanup. EPA may also undertake
the remedy itself using the Superfund and seek recovery
of its costs from responsible parties. If responsible
parties pay for the cleanup, consumers may eventually
.III-28
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indirectly .contribute to cleanup costs through higher
prices or other means. To the extent that the Superfund
is not reimbursed by responsible parties, those
taxpayers who contribute to the Superfund would bear
the cost.
7 .
AMDAG commented on the appropriateness of the sludge
disposal costs, particularly 1= the sludge is a
hazardous material.
8 .
EPA Response. The selected remedy includes plugging,
seepage control, and water control measures that will
substantially decrease the amount of any sludge
produced. To the extent that the interim treatment
facility generates sludge, it will be stored or
disposed of in accordance with the ARARs described in
Appendix C of the Record of Decision. It is difficult
to estimate interim sludge disposal costs with
precision until further information about the quantity
and characteristics of the sludge is a~~~lable.
AMDAG questioned the adequacy of insurance cost
estimates in the FS.
,
EPA Response. The annual operation and maintenance
costs presented in Appendix L of the FS include a line
item for insurance, taxes, and licenses. This line
item covers typical accident insurance and local taxes.
In addition, the costs for licenses may be minimal as
Federal, State, and local permits are not required for
actions conducted entirely onsite. As such, EPA
believes that the 2 percent line item estimate is
reasonable.
9 .
Mr. Crocker commented that focus on the Yak Tunnel
implies that combinations of Yak Tunn~l and tailing
pile cleanups, which could be less costly, are
dismissed out-of-hand. . He stated that correct
least-cost procedure would require that incremental"
costs be equated across control measures within an
operable unit and across operable units.
EPA Response. A remedy may be conducted in operable
units, provided the response action is cost-effective
and consistent with a permanent remedy. As discussed
previously, the selected remedy meets beth of these
requirements. Given the discrete nature of the response
action, EPA does not believe that simultaneous
consideration of response actions for tailings piles or
other site features would result in a more cost-
effective remedy. The selected remedy provides a
III-29
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12.
13.
flexible approach to integration with future operable
units.
10.
Mr. Crocker also commented that, aside
disposal, EPA supplied no quantitative
cost associated with the environmental
considered alternatives.
from sludge
treatment of the
impacts of its
EPA Response. EPA evaluated alternatives and selected
a remedial action to minimize environmental impacts
associated with the selected remedy. For example, the
remedy includes a monitoring program and contingency
measures to identify and mitigate any impacts. In
addition, EPA identified long- and short-term impacts
associated with the selected remedy. The costs for
these measures are included in the cost of the
alternative through alternatives development and design
and siting factors.
11.
Leadville Corporation commented that its proposal or
the ASARCO proposal should be implemented if either
provides a less costly alternative.
EPA Response. Under CERCLA, the NCP, and EPA guidance,
EPA must evaluate the effectiveness and implementability
of each alternative, as well as its cost. Any
alternative selected must meet the requirements of
Section 121 of SARA. EPA cannot simply select the
least costly alternative identified.
Hecla commented that EPA's flawed remedy selection
process led it to ignore long-term maintenance costs
and that, as a result, the selection process is legally
defective.
EPA Response. As discussed above, EPA calculated the
costs of long-term operation and maintenance during the
detailed analysis of alternatives. EPA also evaluated
the present value of these alternatives. The selected
remedy has the potential to minimize long-term
maintenance requirements.
Hecla asserted that the cost-effectiveness analysis
required by the NCP mandates EPA to consider costs in
terms of remedies that meet applicable or relevant
cleanup goals. Hecla further stated that EPA must
establish reasonable cleanup goals so that cost factors
may be given the detailed analysis they deserve in light
of the most effective technology for obtaining these
goals. Hecla concluded that EPA failed to set
reasonable cleanup goals and standards for the
California Gulch site.
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EPA Response. Under Section 121 of SARA, EPA must
select remedial actions that are protective of human
heQlth and the environment. In addition, as discussed
above, remedial actions that leave any hazardous
substances, pollutants, or contaminants onsite must
attain ARARs at the completion of the remedial action.
This is the degree of cleanup required by statute. In
the FS, EPA analyzed both ccst and ARARs attainment as
required by SARA and the NCP in the ~Ilitial screening
and detailed analysis of alternatives. Section VI and
Appendix C of the Record of Decision describe how the
selected remedy meets these requirements.
14.
Mr. Larry Tanglen and Mr. Henry Harelson questioned if
EPA had estimated costs for Alternatives 5 and 7 and if
the costs included treatment plant operation and
maintenance, including sludge disposal.
EPA Response. The estimated cost for Alternatives 5
and 7 are presented in the Yak Tunnel FS. Sludge
disposal costs are included in the estimates. The
estimated cost of the selected remedy is presented in
the Record of Decision.
TECHNICAL ISSUES IN THE FS
AND PROPOSED PLAN
Commenters raised technical issues and concerns regarding
information contained in the FS and proposed remedial action,
plan.
,
... .
The Department of the Interior stated that it has
information indicating that the geological faults
in the FS figures and discussed in the text were
mislabeled.
shown
EPA Response. S. F. Emmons, the geologist whose 188'6
and 1927 studies of the LeadVille area are considered
the most complete and accurate, was the source for the
information used in the FS. EPA would be interested in
studying any additional information the Department has
for the Leadville area.
...
~ .
Several commenters, including Alpenglow Excursions, the
Lake County Environmental Task Force, and Hecla were
concerned that EPA has limited data on the condition of
the Yak Tunnel and the hydrology of the site.
EPA Response. The Yak Tunnel FS used all information
available from existing sources and obtainable from
ASARCO. Some of the information presented by ASARCO in
their response to the FS has been used in development
of the selected remedy. Additional information on the
111-31
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conditiori of the Yak Tunnel and hydrology of the site
will be collected during the remedial ~esign phase.
3 .
Marsh & Associates questioned the absence of any
radionuclide investigation at the California Gulch site
in general, and at the Yak Tunnel in particular~
EPA Response. Radionuclides will be investigated in a
subsequent operable unit.
4 .
Hecla pointed out the uncertainties concerning surface
water and mine hydrology relating to the Yak Tunnel ana
noted that these uncertainties must be taken into
account in remedy selection and development of cost
estimates.
EPA Response. EPA acknowledges that the geology and
hydrology of the Yak Tunnel area are complex and that
uncertainties exist. EPA has taken a conservative
approach in developing the selected remedy. A
mOfiitoring program and contingency plans are integral
parts of this remedy. Additional data will be obtained
during the remedial design to minimize the
uncertainties associated with implementation of the
selected remedy. Uncertainties were taken into account
during development and selection of remedies and in
cost calculations.
5 .
Hecla stated that due to the lack of ground water data
for the tunnel, many of EPA's conclusions in the FS and
proposed plan "cannot be supported by fact." ASARCO
poi~ted out that "limited data were available to EPA"
and that "the effect that partial plugging may have on
the mine workings and seepage cannot be predicted
reliably." On the other hand, ASARCO also stated that
there is extensive data on the underground workings and
that further studies and additional data are not
necessary.
EPA Response. EPA again acknowledges the complex nature
of the Yak Tunnel system. However, all available ground
water data and extensive historical information on the
Yak Tunnel were used to develop a conceptual model of
the ground water system associated with the Yak Tunnel.
EPA believes that this model was sufficient to develop
and evaluate remedial alternatives. The selected
remedy accounts for potential limitations in the model
and contingency plans have been developed in case
unanticipated problems occur.
Based on review of information made available by ASARCO
and other parties, EPA believes additional information
will be necessary to complete the design of the
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8 .
~
selected remedy. The material made available by ASARCO.
is incomplete and does not always include information
on mine workings location relative to the surface.
There is very little, if any, infor~ation on rock
conditions, both from a strength or ground water flow
point of view.
6 .
The State of Colorado noted a reference in Section 3 of
the FS that, due to the lack of data, contamination of
deep ground water systems is not considered. The State
would prefer that a short discussion of the implica-
ticns of this exclusion on the FS be included.
EPA Response. The flooded mine zones of the Yak Tunnel
may currently contribute contaminated ground water to
the deep ground water system located east of the Pendry
fault. EPA evaluated the effects of alternatives
considered in the detailed analysis section of the FS
on the deep ground water system and found that minimal
increases in flow to this system would occur.
7 .
The State of Colorado commented that the statement in
Section 8 of the FS that there "should be an
improvement in fish habitat as a result of a cleapup"
is unsubstantiated. The State would prefer a more
detailed qualitative and quantitative assessment of .the
anticipated aquatic habitat improvements.
EPA Response. To the extent that water chemistry is a
limiting factor for aquatic life, any improvement in
water quality should result in an improvement in aquatic
habitat. Further information on aquatic life and
potential habitats will be addressed in future
California Gulch site studies.
The Department of the Interior commented that the FS is
divorced from surface materials deposited in and along
California Gulch. The Department noted that release of
treated wat~r to.California Gulch may affect downstream
conditions favorably or adversely. Specifically, it
was stated that treated water may flush accumulated
precipitate from the streambed and that water-sediment
interactions would increase dissolved metal
concentrations through adsorption, and would certainly
increase total metal concentrations. The Department
further noted that treated water would improve the
quality of ground water in the alluvial aquifer.
EPA Response. EPA recognizes that chemical interactions
will occur between the treated water discharged from
the interim treatment plant and the gulch sediments.
However, the selected remedy will significantly reduce
the total metal load to the California Gulch system
and, thus, will constitute a key component in the
III-33
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10.
,
overall site remedy. Nevertheless, EPA recognizes that
remobilization may be greatly affect the quality of
shallow ground water and surface water along California
Gulch. Additional information concerning remobilization
of metals is being analyzed as part of the Phase II RI
report for the California Gulch site.
9 .
Hecla commented that the FS ignores the institutional
issues associated with operating treatment and disposal
facilities in perpetuity. Hecla also stated that the
FS ignored sludge disposal and asserted that the remedy
would increase rather than decrease the amount of
hazardous waste in the environment.
EPA Response. EPA is aware of the problems involved
with a remedial action that must be operated in
perpetuity. EPA has modified its remedy to include
tunnel plugging, which will minimize the amount of
sludge requiring disposal and eliminate the need for
perpetual tunnel maintenance. EPA disagrees that the
remedy will increase the amount of hazardous waste in
the environment. The tunnel discharge now distributes
metals widely throughout the environment and
contributes to widespread contamination. Both the
preferred alternative and the selected remedy provide
for collection, treatment, and disposal of sludge,
which will contain and minimize dispersion of ~etals in
the environment. The questions raised by Hecla
regard~ng implementation of the remedy have been
dddressed in the Record of Decision. EPA has filed an
action under CERCLA seeking to have defendants
implement and maintain the remedy.
EPA's Hazardous Waste Research Laboratory commented
that backfilling mine voids with a permeable material
such as mine tailings or quarry rock, as discussed in
part in Alternative I, would not isolate the sulfide
zones from contact with water nor would it necessarily
reduce the quantity of water moving through the min~
voids. It was further commented that only if the mine
voids were filled with an impermeable material would
this approach be effective.
EPA Response. EPA agrees with the above contention.
It was for that reason that the backfilling by means
other than a type of concrete were rejected during the
development of alternatives in the FS. In the initial
screening of alternatives, it .was further recognized
that even backfilling with grout may not be technically
feasible, in that it may not be possible to fill all
the mine voids. .
III-34
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.
11.
The pepartment of the Interior commented that the effect
of surface solids, which can be washed into the gulch
dur~ng runoff periods, has not been considered carefully.
EPA Respcnse. EPA agrees that surface solids (such as
mine wastes, tailings, and soils) can be washed into
California Gulch. These will be addressed in a
subsequent operable unit.
12.
The State of Colorado requested that the ipformation
concerning wetlands (paragraph 3, page 8-22) be
clarified. The State noted that there appears to be
misinformation on plant toxicity and remobilization ot
metals; plants that are metal-tolerant exclude or
encapsulate metal ions and, therefore, are not affected
by metal concentrations. The State also stated metal
uptake often occurs in acidic conditions, and so the
remobilization statement is confusing.
EPA Response. Some wetland plants that.~re
metal-tolerant actively exclude metals ~rom transter
into root and leaf structures. Other wetland plants
uptake metal ions, storing them in rhizome and root
structures and seasonally trans locating them to
aboveground vegetative structures. Similarly, some
plants bind the ions to organic molecules within the
plant-structure and ions are immobilized in this
manner. In general, evidence of plant toxicity has
been linked to metal concentrations in the leaf
material elevated beyond some threshold level, the
latter dependent on the plant species and other ions
present. Thus, in metal-tolerant perennial species
that trans locate metal ions, over several seasons ion
accumulation in leaf tissue may exceed the tolerance
limit.
Metal uptake by plants frequently occurs under acidic
conditions because metal ions are more avail~ble in -
soil-water solutions. Metal ions are released from
exchange sites in organic soil substrates and are
dissolved from precipitated forms under acidic
conditions. Remobilization thus refers to movement
from the soil substrate, rather than movement out of
the plants.
13.
The State of Colorado commented that Appendix I of the
. FS states that ground water flow away from the mined
area would be attenuated. The State questioned whether
this statement is substantiated and suggested that,
given the lack of specific knowledge about ground water
movement in the area, statements about ground water
should be qualified.
III-35
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15.
16.
EPA R~sponse. The nonmineralized geologic formations
in the northern port~on of the Leadville Mining District
contain significant quantities of carbonate nlateria1s
(limestone) that will buffer acidic water that might
flow north from the mine workings. Therefore, it is
unlikely any low pH water would affect the ground water
in the upper Evans Gulch area. Acidic water that would
flow toward upper California Gulch would be attenuated
by nonmineralized geologic formations. Furthermore,
the selected remedy incorporates a monitoring program
to detect contaminant migration and contingency measures
to deal with this migration should it Occur and be
judged to pose a health or environmental risk.
14.
The State of Colorado noted that the assumption that
roasted waste could be non-acid generating (page 5-23
of the FS) may be in error based on data from the Eagle
Mine. The State suggested that this statement be
revised to indicate that site-specific testing would be
used to determine the nature of the material.
EPA Response. Specific oxidation processes would be
designed to fully oxidize the pyritic materials under
consideration and produce a non-acid generating waste.
If this option is pursued, laboratory testing would be
undertaken to confirm design criteria of. the oxidation
process.
The State also commented that the scre~ning of
alternatives should consider the impacts and hazards
associated with the implementa~ion of those
alternatives (i.e., roof falls or contact with slimes
during tunnel rehabilitation). The State noted that
such considerations could be important in the screening
process and certainly must be considered in the design
of the preferred alternative.
EPA Response. Construction-related risks were
considered in the detailed analysis portion (Section 8)
of the FS. EPA agrees that safety conditions must be
taken into account during remedial design.
AMDAG commented on the technical adequacy of the High
Density Sludge (HDS)/ion-exchange treatment system in
dealing with changes to influent conditions.
EPA Response. EPA's proposed remedy has been modified
to include an interim treatment system, so HDS treablent .
will not be used. Additional Yak Tunnel flow and
chemistry information will be obtained during the
remedial design phase. EPA agrees that additional work
is required to design a treatment system that will
properly perform under all circumstances.
III-36
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17.
18.
19.
20.
21.
AMDAG stated that EPA's proposed remedy did not
adequately address surge events.
EPA Response. EPA disagrees with this comment. Both
Alternatives 5 and 7 incorporated provisions for ponds
to collect surges that could occur during tunnel
rehabilitation or after implementation of the remedy.
EPA's selected remedy includes construction of surge
ponds prior to any entry into the tunnel. In addition,
the placement of three plugs within the Yak Tunnel w~ll
virtually remove the potential for surges after the
plugs are constructed.
~lDAG stated that oxidation of sulfides will continue
to be a problem unless conditions are modified to reduce
the contact of atmospheric oxygen with sulfides.
EPA Response. EPA agrees and has selected a remedy
that will include a plugging cpmpcnent. Plugging will
minimize the amount of sulfide oxidation, although some
sulfides are expected to remain above the equilibrium
ground water level after plugging.
~IDAG commented that with plugging, the ground water
flow path may increase, and that plugging may
significantly influence ground water chemistry.
EPA Response. The s~lected reffiedy will influence
ground water chemistry and flow. However, it is not
expected to result in unacceptable ground water
contamination in neighboring ground water regions. As
an additional safeguard, the selected remedy includes a
monitoring network to sample water chem~stry and ground
water levels in and around the flooded mine zones. If
ground water impacts are identified, contingency
pump-and-treat measures will be implemented.
AMDAG stated that the equations given by Sturnnl and
Morgan (1981) do not reflect the time chemistry of acid
generation from iron sulfide oxidation and presented an
unpublished paper by Sullivan, Reddy, and Yelton (1987).
EPA Response. EPA appreciates the additional
information provided by AMDAG. Rate reaction
calculations would only be relevant during the initial
stages of the acid mine drainage formation. However,
the system has already reached the state of acid
gene~ation.
Leadville Corporation agreed that the Diamond/
Resurrection plug would reduce tunnel discharge from
the Yak portal by 20 percent. However, Leadville
Corporation stated that modeling undertaken on its
behalf indicated that the.metal mass loading would
III-37
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22.
23.
24.
probably incr~ase rather than decrease as suggested in
Appendix E of the FS. According to Leadville
Corporation, this would be due to (~) elimination of
the buffering capacity of water from the Resurrection
area, and (2) 1055 of dilution by this water. .
Leadville Corporation suggested that these two effects
should be taken into account when the proposed
treatment plant moves from the conceptual to the design
phase.
EPA Response. EPA agrees that the Resurrection plug
alone, by cutting off entry of the higher pH water to
the tunnel, could reduce the amount of sludge
precipitation in the underground workings and, hence,
increase the metal loads at the portal. However, the
selected remedy employs at least two additional plugs
located downgradient from the R~surrection plug and
hence would prevent any increased metal load from
exiting the tunnel. F.urthermore, the total amount of
metal that is dissolved from the mineralized rock would
decrease as sulfide rock would be inundated by rising
ground water.
Alpenglow Excursions and Mr. Rasmussen questioneq how
the sludge by-product from the treatment plant would be
disposed of.
EPA Respons~: Sludge from the interim treatment
facility will be stored in the surge ponds on an
interim basis. A permanent disposal option will be
implemented in conjunction with a future operable unit.
Alpenglow Excursions questioned what kind of provisions
would be made for periods of malfunction or downtime
due to floods, breakdowns, or human error. Hecla alsv
commented on the potential for treatment plant upsets.
EPA Response. The surge ponds will be used to allow
sufficient storage capacity for short-term repair of
the treatment plant. Well-trained operating personnel
will minimize operational mistakes, and a preventive
maintenance program and proper plant design and
construction will minimize breakdowns. The ponds will
be protected from a lOa-year flood by a system bypass
and the plant will be located outside the floodplain
area.
Alpenglow Excursions asserted that the Yak Tunnel, parts
of which were constructed 100 years ago, would not
accommodate modern mining equipment. Mr. Robert Dechant
felt that many of the mining techniques discussed in
the FS wouldn't be feasible for the Yak Tunnel.
III-38
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26.
,
EPA Response. The tunnel was ccnstructed to be a.
nominal 8 feet square in size and to accommodate a
locomotive engine and ore cars. Even with collapsed
walls, the tunnel should be large enough to a~commodate
equipment considered for use in rehabilitation. Tunnel
sections with collapsed walls or roof will be cleared
out and reinforced to maintain access. Based on .
information available to EPA regarding tunnel
conditions and modern mining techniques, EPA believes
that tunnel rehabilitation and maintenance would be
feasible. However, an alternate access method
identified in the selected remedy is to construct a new
shaft for construction of the portal plug. This shaft
could later be used as part of the water level control
system.
25.
The Department of the Interior commented that the
2-million-gallon surge control pond, or wetlands,
proposed for treatment of the acid drainage from the
Yak Tunnel would create an attractive, but dangerous,
habitat for migratory waterbirds. The Department
suggested instead that a closed treatment system or
other migration measures be used.
EPA Response. EPA's selected remedy will utilize the
surge ponds on an interim basis to collect anq treat
surges from the tunnel that may occur during plug
construction and as a treatment facility for aci~
dra1nage that may occur after plug installation.
Wetlands treatment is not a part of the selected
remedy. EPA recognizes that waterfowl may be attracted
to the ponds and will work with the Department of the
lnterior and the Colorado Division of Wildlife to
mitigate potential impacts on waterfowl.
Mr. Bates stated that overflows will result from any
alternative using mine seals to partially (or totally)
seal the Yak Tunnel. He noted that overflow points
would have. to be identified and measures included to
collect and handle the overflow water, which would
likely still be contaminated. He also stated that the
full or partial plugging alternatives appear to. assume
no overflow of contaminated water and only address
direct discharge from the tunnel portal.
EPA Response. In analyzing alternative remedial actions,
EPA assessed the potential for ground water migration
and surface seepage in both the Evans Gulch and
California Gulch areas. Because of uncertainty
.associated with the effects of tunnel plugging, EPA has
developed a monitoring plan and contingency measures to
address poss1ble seepage or ground water contamination.
The contingency measures, as well as components of the
remedy addressing seepage, are described in the Recor~
of Decision.
III-39
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29.
30.
27.
Both the Department of the Interior and the State of
Colorado submitted lists of editorial changes that
should be made to the FS.
EPA Response. These corrections have been included in
Appendix B of this Responsiveness Summary.
28.
Alpenglow Excursions, ASARCO, Hecla, Leadville
Corporation, and the State ot Colorado questioned
whether physical hazards to workers involved in
. implementing the proposed alternative had been fully
addressed. in the FS or sufficiently considered.
EPA Response. The physical hazards of rehabilitating
the Yak Tunnel were taken into consideration during the
detailed analysis of alternatives. Although the
conditions within the tunnel may be poor, modern mining
technology can be used to rehabilitate the tunnel
safely. Nevertheless, in part because of concern .about
worker safety, the selected remedy minimizes the amount
of work that will be necessary in the tunnel. All
applicable health and safety requirements will be met.
Hecla commented that EPA failed to properly scopa
remedial or removal measures suitable to abate the
threat and set priorities for implementation of the
measures in accordance wi th 40 CFR Secti9n 300.68 (e) (l) .
Hecla also commented that EPA has not given appropriate
review to a suite of alternatives.
EPA Response. Section 5 of the FS ("Scoping of Response
Actions and Associated Technologies") describes how EPA
determined the scope of response actions suitable to
abate the threat from the Yak Tunnel. Sections 5, 6,
7, and 8 of the FS document the full range of
alternatives considered by EPA and the reasons why they
were rejected or retained. EPA has also set priorities
for response action. EPA conducted a removal action to
ensure that no families were using contaminated ground
water for drinking water. In addition, EPA's
preparation of an FS for the Yak Tunnel operable unit
indicates EPA's priority for remedial action.
Hecla commented that EPA failed to address numerous
factors relative to the effectiveness, feasibility, and
cost-effectiveness of var~ous technologies.
EPA Response. . Hecla's c.onunents did not identify the
numerous factors, so EPA is not sure which factors were
meant. Sections 7 and 8 of the FS describe the initial
screening and detailed analysis of alternatives based
on effectiveness, implementability, and cost.
III-40
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32.
33.
34.
31.
Hecla commented that EPA tailed to evaluate the
.potential threat to human health and the environment
associated with excavation, transport, and redisposal,
or containment as required by 42 USCSection 962l(b) (i) (G).
EPA Response. Several alternatives, including
Alternatives 3 and 4, involved excavation, transport,
and redisposal. The impacts from implementation of
these alternatives are discussed under the screening
analysis in Section 7. These alternatives were
screened out during initial screening in part because
ot unacceptable environmental impacts. It was, .
therefore, unnecessary to complete a more de~ailed
human health and environmental impact analyses.
The selected remedy does not incorporate excavation,
transport, and redisposal. Removal and disposal of the
interim treatment plant sludge will be addressed in a
subsequent operable unit. Tunnel plugging is
fundamentally a containment remedy. E? -. fully
evaluated the impacts of tunnel pluggi~: and developed
a remedy that would mitigate potential impacts.
Numerous commenters, including ASARCO, Hecla, the,State
of Colorado, and Alpenglow Excursions, raised questions
about the feasibility of rehabilitating the Yak Tunnel
and the costs, safety considerations, and level of
effort required to rehabilitate and maintain the
tunnel.
EPA Response. EPA agrees that rehabilitation and
maintenance of the tunnel could be difficult, but
believes that it is well within the scope of current
technology and, provided it is carried out with
experienced personnel, this work would be feasible and
implementable. Neverthel~ss, the selected remedy
minimizes the amount of tunnel rehabilitat~on that
would be necessary.
Hec~a commented that the stated goal of the FS provides
no basis to determine which remedies, if any,
cost-effectively attain such goals.
EPA Response. The purpose of an FS is to evaluate
alternative remedies. Part of the remedy selection
process includes determin~ng the degree of cleanup
necessary to protect human health and the environment.
The degree of cleanup is described in Section 4 and
Appendix C of the FS. Alternatives were analyzed based
on their attainment of these goals.
Hecla commented that the FS seemed to assume that the
treatment facility'would be located at the portal and
III-41
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35.
36.
that other alternatives, such as location of the plant
at the confluence of California Gulch and the Arkansas
River, were not or were only superficially addressed.
EPA ResDonse. Under ~lternative~ considered
the treatment facility could be located near
confluence. The specific location was to be
during the design phase.
in the FS,
the
addressed
ASARCO stated that it was a relatively minor
contributor to historical mining disturbances in
California Gulch, including development ~nd use of the
Yak Tunnel, in the vicinity of the California Gulch
site.
EPA Response. The relative contribution of particu~ar
parties to the contamination proble~ is not relevant to
the selection of remedy.
ASARCO suggested that it is not only the sulfide rock
that causes a water quality impact, but that oxidized
mineral-bearing rock also can cause water quality
problems.
,
EPA Response. EPA agrees with this comment but notes
that the sulfide rock is a najor source of
contamination. !t is anticipated that ~unnel plugging
will result in inundation of sulfide zones as well as
some oxide and non-mineralized areas. Monitoring and
contingency neasures are incorporated into the selected
remedy to deal with any water quality problems should
they arise.
PUBLIC PARTICIPATION PROCESS
Hecla made numerous comments about responsible party and
public participation in the remedy selection process. EPA
also received comments during the public meeting about public
participation. These are described below. .
1.
Hecla commented that it is entitled to raise all
objections to the process of remedial action selection
at the time when all components of a California Gulch
remedy have been published. Hecla also stated that
division of the response action into operable units
restricts Hecla's constitutional and statutory rights
to participate in the remedy.selection process as a
whole, rather than in ad hoc segments.
III-42
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restricts Hecla's constitutional and statutory rights
to participate in the remedy selection process as a
whole, rather than in ad hoc segments.
EPA Response. EPA disagrees with this comment. Under
Section 300.68(c) of the NCP, response actions may be
conducted in operable units. As discussed above, EPA
selected the operable unit remedy in accordance with
the CERCLA, SARA, and the NCP. As described in
Section IV of the Record of Decision, EPA complied w~th
all statutory and regulatory provisions regarding public
participation in the remedy selection process.
2 .
Hecla stated that the RI/FS process is not a true
administrative proceeding, is ad hoc, and is unrelated
to rulemaking. Hecla also stated that the process is
not committed to a single administrative agency, but
requires the contribution of several state and federal
agencies.
EPA Response. The process for selection of remedial
actions is described in the NCP (40 CFR
Section 300.68). Under the NCP, the lead agency
conducting the remedial action shall, as appropr~ate,
undertake an RI/FS and select a remedy 140 CFR .
Section 300.,68(d) (i)]. EPA is the lead agency for the
California Gulch site. As part of the remedy selection
process, EPA must consult with the State of Colorado.
See 42 USC Section 962l(d) (2) (A) (ii), (f). To identify
,and ensure compliance with ARARs, EPA also has
consulted with various federal agencies.' Along with
the public, federal agencies were given an opportunity
to comment on the FS and proposed remedial action plan.
3 .
Hecla asserted that the RI/FS process is subject to
supervision of the federal court and compliance with
the Federal Rules of Civil Procedure. Hecla also
stated that remedy selection ~s a matter for judicial
rather than administrative determination.
EPA Response. EPA has the authority to undertake
response actions and order responsible parties to
undertake response actions without supervision of a
federal court or compliance with the Federal Rules of
Civil Procedure (see 42 USC Sections 9604 and 9606).
EPA may also seek judicial relief as may 'be necessary
to abate threats to public health or welfare or the
environment under 42 USC Section 9606. In this
,instance, EPA has filed an action seeking to have
responsible parties implement the remedy selected by
EPA. Under 42 USC Section 9613(j), judicial rev~ew of
any issues concerning the adequacy of any response
action taken or ordered by EPA is limited to the
administrative record.
III-43
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7.
4 ,
Hecla commented that the RI/FS process is
constitut~onally defective because EPA has not provided
defendants with a meaningful opportunity for comment
and input into the process such that due process.
requisites could be satisfied. Hecla protested EPA's
unauthorized actions and claimed that the comment
period was a nullity and that any decision based on the
self-serving, one-sided FS and proposed remedial action
plan would be arb~trary, capricious, in excess of EPA's
jurisdiction, and unauthorized by law,
.EPA Response. EPA disagrees with this comment. As
noted above, EPA has conducted the remedy selection
process in accordance with all statutory and regulatory
requ~rements. Various defendants in United States v.
Apache and Energy Minerals Co., including Hecla, were
g~ven the opportunity to playa substantial role ~n the
remedy selection process. Some of these opportunities
are described in Section IV of the Record of Decision
and Appendix A of this Responsiveness Summary. EPA has
carefully considered comments, information, and
proposals received from defendants and other members of
the public. The Record of Decision and this
Responsiveness Summary document how these comment~ have
been incorporated or addressed.
5 .
Hecla asserted that the RI/FS documents are nothing
more than summaries of expected testimony of expert
witnesses.
EPA Response. EPA disagrees with this comment. Under
40 CFR Section 300.68, EPA conducts an RI/FS to
determine the nature and extent of the threat presented
by the release and to evaluate proposed remedies,. The
RI/FS documents are part of the adrnin~strative record
for judicial review.
6.
Hecla commented that the conflicting role of EPA and
the State of Colorado led to duplications and
inconsistencies.
EPA Response. EPA developed and selected the remedy
for the Yak Tunnel operable unit in consultation with
the State of Colorado. Studies completed by the State
are part of the administrative record upon which EPA
based selection of the remedy.
Hecla commented that EPA's analysis of the California
Gulch site has so confused the nature of contaminat~on,
its sources, the relationship of the Yak Tunnel to the
rest of the site, and the sequence of reports and.
studies that it is impossible for the type of detailed
and systematic consideration of environmental, economic,
III-44
-------
and institutional issues and impacts as mandated in
both CERCLA and the National Environmental Policy Act.
EPA Response. The Executive Swnrnaries of the Phase I
RI and-the FS briefly describe the sources and nature
of site contamination. The introductions to both the
documents also describe the Superfund remedy selection
process for the California Gulch site and how the
various documents relate to this process. The FS
describes the Yak Tunnel and the function of the
operable unit. The FS includes detailed analyses of
alternatives as required by the NCP.
8 .
Hecla cocrnented that EPA has foreclosed interested
parties from any meaningful opportunity to provide
reasonable comment and information regarding potential
remedies. Specifically, Hecla noted that EPA has made
no determination that good faith negotiations with
responsible parties are not or were not possible as
required by Section 122 of CERCLA and further stated
that this systematic exclusion of parties from the
remedy selection process has deprived EPA of potentially
valuable insight and experience. Hecla also asserted
that EPA's failure to take a constructive role i~ site
remediation, including entry into agreements with
responsible parties, has created a long and complex
lawsuit and indicates a complete disregard.for the
mandates of CERCLA.
EPA Response. In accordance with guidance applicable
at the time, EPA sent notice letters in 1983 to
potentially responsible parties to give them the
opportunity to perform the RI/FS for the California
Gulch site. All declined to do so. Nevertheless,
throughout EPA's conduct of the RI/FS, interested
parties reviewed information and submitted proposed
remedies to EPA. EPA has held numerous meetings with
interested parties, including defendants, to obtain
information ~bout the site and to hear the views of
various parties. EPA has carefully considered these
comments and incorporated various aspects of proposed
remedies into the selected remedy. EPA plans to enter
into formal settlement discussions under Section 122
for responsible party performance of the selected
remedy.
9 .
Hecla stated that the timing of release and the comment
periods on the Phase I RI, the FS, and the proposed
remedial action plan stymied responsible party
cooperation in the best possible remedy. Specifically,
Hecla noted that the FS and proposed remedial action
. plan were released during the comment period on the
Phase I RI and that EPA provided only a few weeks for
public review.
II1-45
-------
11.
12.
EPA Response. Even though a public comment period is
not required by CERCLA or the NCP, EPA held a 30-day
COIT~ent period on the Phase: RI. Comments were due
July 12, 1987. EPA granted all requests for extensions
of time to comment on the RI. The FS was released to
defendants for comment on July 6, 1987. The NCP
requires a 21-day comment period on FSs. However, EPA
held a 90-day comment period on the Yak Tunnel FS. EPA
believes that defendants had ample opportunity to
comment meaningfully. Indeed, the comments of or.e
defendant were nearly as long as the FS itself.
10.
Hecla commented that EPA ignored substantive public
comments at the September 1, 1987, public meeting in
development of its preferred alternative.
EPA Response. The proposed remedial action plan, which
identified EPA's preferred alternative, was released in
August 1987, prior to the publ~c meeting on September 1.
During the public meeting, the Collegiate Peaks
of Trout Unlimited .suggested that copies of the
should be sent to the libraries in Buena Vista,
Canon City, and Pueblo.
Chapter
FS
Salida,
EPA Response. EPA sent copies of the FS to the
libraries in those cities and added the suggested
recipients' addresses to the California Gulch mailing
list so future documents would be sent there as well.
The Collegiate Peaks Anglers expressed disappointment
that the availability of the proposed remedial action
plans sent to the Buena Vista, Salida, Canon City, and
Pueblo libraries was not publicized. This group
believes that the public would have had more input if
EPA had issued public notices in these communities.
EPA Response. EPA will endeavor to provide additional
not~ce to these communities in the future.
OTHER COMMENTS
1 .
The Department of the Interior commented that
consideration must be given to the impacts on mineral
resources remaining in the Leadville Mining District.
The Department cited Bureau of Mines information that
deposits of gold, silver, copper, lead, and zinc remain
in the Leadville workings. Leadville Mining and Milling
Corporation also expressed concern for the future
workings of the company as well as Leadville
Corporation and Highland Consolidated Mining
Corporation should the water levels within these other
mines rise due to the plugging of Yak Tunnel.
1II-46
-------
EPA ReSDonse. Plugging of any or all portions of the
Yak Tunnel will not halt recovery of remaining mineral
resources. However, present or future operators may
need to dewater their facilities. For example, the
proposal of Leadville Corporation discussed above
includes installation of a tunnel plug, dewatering of
the mine workings, and treatment and discharge to Big
Evans Gulch.
2 .
Leadville Corporation asserted that water draining from
the Leadville Corporation's property into the Yak
Tunnel is clean and that it has a value that should not
be wasted.
EPA Response. EPA has reviewed data provided by
Leadville Corporation regarding water quality in the
vicinity of the Resurrection workings, but has not
collected its own data no~ independently verified the
data provided. The selected remedy is not expected to
affect whatever value this water may h~~~ as a
resource.
3 .
ASARCO presp.nted a site history in its response to the
FS, including a histor~ of the Leadville Mining
District and the Yak Tunnel.
EPA Response. EPA has reviewed the information and
included ASARCO's comments in the administrative
record. In addition, EPA incorporated certain elements
into the "Site Histo~y" section of the Record of
Decision.
4 .
Mr. Don Seppi of Leadville asked what the schedule is
for EPA's implementation of the Yak Tunnel remedy.
EPA Response. The schedule for implementation of the
Yak Tunnel selected remedy is presented in the Recorq
of Decision.
5.
ASARCO, Hecla, and others made numerous comments on
legal and technical matters.
EPA Response. In this Responsiveness Summary, EPA
separately identified and responded to significant
comments, criticisms, and new data presented during the
public comment period. EPA does not necessarily agree
with any comment, criticism, or information submitted
for which a specific response was not prepared.
III-47
-------
INDEX TO COMMENTS
Name/Organization
ASARCO Incorporated
Acid Mine Drainage Action
Group (AMDAG)
Alpenglow Excursions
Bates, Mr.
Beach, Will
Collegiate Peaks Anglers
Collegiate Peaks Chapter
Trout Unlimited
Colorado Historical Society
Colorado, State of
Crocker, Mr.
Dechant, Robert
Department of the Interior
Elder, Robert L.
EPA--Hazardous Wastp
Research Laboratory
Harelson, Henry
Hecla Mining Company
Highland Consolidated
Mining Corporation
Lake County Environmental
Task Force
Leadville Corporation
Leadville" Mining and Milling
Corporation
Page Number for Section. III
1-4, 6, 11, 12, 16-26, 32,
40-42, 47
14, 27, 29, 36, 37
n
10, 26, ~7, 28, 31, 38-40
39
22
10, 12, 46
46
26
27, 33, 35, 36, 40, 41
29, 30
27, 28, 38
9, 14, 26-28, 31, 33, 35,
39, 40, 46
15
34
31
1-9, 11, 12, 16-21, 23, 26-28,
31, 32, 34, 38, 40-47
46
11, 12, 27, 31
2, 3, 5, 7, 12, 17, 18, 20,
21, 23, 30, 37, 38, 40, 46, 47
9, 12, .15, 46
III-48
-------
Marsh & Associates
32
Moats, Ed
27
Paden, Frank
27
Queener, E. H.
29
Rasmussen
38
Resurrention Mining Company
and Newmont Mining
Corporation
1-4, 7, 17-19, 21
Seppi, Don
48
Stout, Carvel
28
Tanglen, Larry
31
TUSCO Incorporated
13, 14
III-49
-------
, '
4 .
5 .
IV. EXPLANATION OF DIFFERENCES BE~1EEN THE
PROPOSED PLAN AND THE SELECTED REMEDY
EPA identified Alternative 5 as the pre:erred alternative in
the proposed remedial action plan for the Yak Tunnel
operable unit. The key elements of this alternative were:
I .
Rehabilitation of the tunnel to reduce the probability
of surge events and to ensure the continued collection
of contaminated water;
2 .
Diversion' of surface water in upper California Gulch to
reduce infiltration to a portion of the Yak Tunnel;
3 .
Surge protection an~ short-term treatment ponds to
minimize the effects of sludge and water surges that
could occur when the tunnel is entered for ongoing
field investigations and rehabilitation, and to regulate
flow to the treatment plant;
A physical treatment plant incorporating a
neutralization-precipitation process; and
A structure to convey treated water to the lower
reaches of California Gulch or the Arkansas River.
EPA also recognized that Alternative 7 in the FS, which
includes partial plugging of the Yak Tunnel, had the
potential to decrease the contaminant mass loads and the
quantity of water to be treated. Therefore, EPA retained
the possibility of incorporating a plugging component into
the remedy at a future date.
As discussed previously, EPA received, extensive comment on
the proposed plan and has modified the remedy to address
major concerns about tunnel rehabilitation and maintenance
and perpetual operation of the treatment system. The
selected remedy is a logical outgrowth of the remedy
identified in the proposed plan and other alternatives
developed and evaluated in the FS. The components of the
selected remedy were conceptually evaluated in the FS and
the selected combination of actions was well within the
range of alternatives the public could have reasonably
anticipated EPA to be considering.
The primary difference between Alternative 5 and the
selected remedy is the inclusion of a tunnel plugging
component in the selected remedy. In the proposed plan, EPA
retained the possibility of partial plugging, but identified
four concerns about potential e~fects of plugging. These
were concerns about (1) predicting the effects of tun~el
IV-l
-------
plugging based on the limited data available about mine
workings and hydrogeological conditions, (2) the influence
of dewatering activities in the Black Cloud Mine, (3) risks
of contaminating the Leadville water supply through
migration of contaminated water towards Big Evans Gulch, and
(4) effects on future mineral resource development in the
area.
Because of issues raised and information provided during the
public comment period, EPA re-evaluated its concerns about
tunnel plugging. EPA determined that concerns about ground
water movement, Black Cloud operations, and the Leadville
water- supply could be adequately addressed through water
control measures, a pump and treatment system, a
comprehensive monitoring program, and contingency plans. In
addition, EPA determined that tunnel plugging would not
restrict future- resource development as water could be
pumped from mine workings and treated.
o
rV-2
-------
v.
REMAINING CONCERNS
OPERABLE UNITS
o
As discussed previously, EPA anticipate~ conducting response
actions for the California Gulch Superfund site in operable
units. An operable unit is defined in the NCP as "a
discrete part of the entire response action that decreases a
release, threat of release, or pathway of exposure."
Implementation of operable units may begin before selection
of a final remedial action for the site if the operable
units are cost-effective and consistent with a permanent
remedy.
EPA plans three operable units for the California Gulch
site: the Yak Tunnel operable unit, an operable unit
addressing mine wastes and ephemeral drainages, and the
overall site remedy. An RIfFS has been or will be prepared
for each operable unit.
Remedy selection for the Yak Tunnel operable unit has been
complet~d. The attached Record of Decision documents EPA's
decision to plug the tunnel to reduce metals loading on
California Gulch and the Arkansas River. This decision was
based on the Phase I RI and the Yak Tunnel Operable Unit FS.
The second operable unit will cover mine waste east of the
Town of Leadville, excluding the slag piles, and ephemeral
drainages. Preparation of a Phase II RI is now under way.
The third operable unit will address overall site
remediatiun. This will be initiated after completion of the
necessary studies required to characterize the nature and
extent of contamination for the remaining portion of the
California Gulch Site. Generally, this includes
investigation of air, radiation, and organic contamination.
In addition, additional characterization ot soil, sediments,
and surface and ground water will be done. EPA is now
preparing the scope of work for the Phase II RIfFS.
ENDANGERMENT ASSESSMENT
A Preliminary Endangerment Assessment (PEA), using the data
compiled during the Phase I and Phase II RIot the
California Gulch site, will be prepared to characterize the
nature and extent of threats to public health and welfare.
and the environment. The PEA will be prepared pursuant to
all applicable EPA guidance and will be based on all
available data. The PEA will lead to the identification of
data gaps that need to be filled by Phase III RI sampling.
A complete Endangerment Ass~ssment (EA) that summarizes the
contaminants of concern, the possib~e pathways of exposure,
and the threats to public health or welfare or the
V-I
-------
environment posed at: the California Gulch site will be
developed following the Phase III RI. Much of the data
required to perform the complete EA will be collected during
Phase 1:1 activities; however, additiunal data, including
all studies conducted at the site and all the data obtained.
during the Phase I and Phase II RI will also be used.
~
.
,
V-2
-------
u
Appendix A
LIST OF COMMUNITY
RELATIONS ACTIVITIES
-------
G
o
o .
o
o
o
o
Appendix A
LIST OF COMMUNITY RELATIONS ACTlVITIES
o
Onsite interview for Community Relations Plan (October
1985)
o
Fact Sheet on Superfund process (January 1985)
o
First public meeting on RI/FS process (February 7,
1985)
o
Draft Community Relations Plan Update (November 19,
1985)
o
Public meeting on RI/FS status (December 3, 1985)
o
Fact Sheet on status of RI activities (April 1986)
o
Public meeting to update status of RI/FS process
(April 7, 1986)
o
Fact Sheet on Yak Tunnel remedial alternatives (June
1987)
o
Public comment period on. Phase I RI Report (June 9
through July 12, 1987) (provided extensions for comment
upon request)
o
Letters to defendants enclosing copy of Phase I RI
Report and notifying them of opportunity to comment
(June 9, 1987)
Letters to defendents enclosing copy of Yak Tunnel FS
Report and notifying them of opportunity to comment
(July 6, 1987)
Public comment period on Yak Tunnel FS Report (Ju~y 7
through October 5, 1987)
Press release on opportunity to comment on Yak Tunnel
FS Report (July 7, 1987)
Fact Sheet mailed to over 100 people on Yak Tunnel
remedial alternatives (July 1987)
Letters to defendants notifying them of extension of
comment period on Yak Tunnel FS Report (August 7,
1987)
Press release on availability of Proposed Remedial
Action Plan for Yak Tunnel (August 17, 1987)
A-I
-------
o
o
o
o
o
Letters to defendants enclosing copy of Proposed
Remedial Action plan for the Yak Tunnel Operable
and notifying them of opportunity to comment
(August 19, 1987)
Unit
o
Full-page notice in Leadville Herald Democrat on brief
analysis of plan and alternative plans (August 20,
1987)
o
Copies of propo5ed plan for Yak Tunnel mailed to
complete mailing list and information centers (July
1987) .
~
o
Copies of Administrative Record to information centers
(September 15, 1987)
o
Letters to defendants notifying them of the
availability and location of the interim administrative
r~cord for the California Gulch site (September 24,
1987)
o
Press release (August 25, 1987) and articles on
location and availability of administrative record
published in Leadville Herald Democrat (October ~,
1987), and Rocky Mountain News (October 2, 1987)
o
Public meeting on the Yak Tunnel FS Report
(September 1, 1987)
o
Copies oi.September 1, 1987 public meeting transcripts
to all commenters a~ the public meeting and tQ
information centers (February 1988)
ONGOING ACTIVITIES
o
Meetings with Lake County Commissioners
o
Meetings with Leadville City Council
Responses to requests for information
Responses to questions about site activities and the
Superfund process
Meetings with concerned citizens and potentially
responsible parties
Information centers with technical information,
studies, and, in Leadville, pleadings from u.S. v.
Apache Energy and Minerals Co.
A-2
-------
(;
.'
Appendix B
YAK TUNNEL FEASIBILITY STUDY REVISIONS
CALIFORNIA GULCH SITE
,
-------
" Page
vii
()
x
xviii,
xviii,
xviii
xix
xx
xxi
xxxii
2-7
2-10
2-12
2-13
Appendix B
YAK T~NNEL FEASIBILITY STUDY REVISIONS
CALIFORNIA GULCH SITE'
Line
2.
23
Col. 2,
Cji2, L3
Col. 3
Cj[2., L11
Col. 3
!6
10
17-18
18
3
14-18
Fig 2-3
16-24
Fig 2-4
Correction
<)
Title for Table 1 should be "Comparisen
of Compounds and Criteria"
"Ferrooxidans" should be "iron-oxidizing
bacteria"
"(ion change)" should read "(ion
exchange)"
To the sentence that ends "effectiveness
of the plug...", add "and its impacts on
the groundwater system and ether mine
drainage tunnels, such as the Leadville
Mine Drainage Tunnel."
"because a similar treatment plant"
should read, "a similar treatment plant"
Replace "deformation" with "stress"
End sentence aft~r "2 min."
"electronics" should be replaced with
"electrons"
Insert title for Table.l; "Comparison of
compounds and Cr iter i"a "
~Iron (960 to 15,500 mg/kg)" shoud
"Iron (9,600 to 15,500 mg/kg)";
"aluminum (1,920 to 14,000 mg/kg)"
should read" al uminum (1,92. O' te
140,000 mg/kg)"
read
Tennessee Creek should have been
labeled.
Add a sentence stating that "Additional
studies are underway which will enhance
our understanding of metal loadings in
the Arkansas River."
Add a note that the percent of
contribution from these sources vary
seasonally.
B-1.
-------
.
Page
{jj
2-15
3-2
3-22
3-22
4-12
7-11
7-12
8-12
8-32
8-40
8-41
Line
30
13-23
1
2
Table
4-2
13
Fig 7-1
Cols 4
and 5
Table
8-7
5
5
Appendix a
(continued)
Correction
"at the end" should read "at the
beginning"
The Department of the Interior noted
that a third study report was completed.
Although never formally published, a
copy has been given to the EPA by the
Bureau of Reclamation.
':
Replace "by bioaccumulation" with "for
bioaccumulation"
"(pages 3-2 to 3-3)" should be inserted
after" as previous ly su:-.-.=.r ized"
A revised table is attached.
,
Reference to "Table 7-2" should read
"Figure 7-2"
Discharge from Yak Tunnel to California
Gulch should be "5" and total flow in
the gulch should be "135."
First entries shcu~d be ~witched.
Headings should be fixed so that second
HDS column falls under Alternative 7
"$123.9 milliQn" should read
"$23.9 million"
Insert "and to ensure there are no
adverse impacts to facilities such as
the Leadville Mine Drainage Tunnel."
after "effectiveness of the plug."
B-2
-------
Revised ~able 4-2
CONTAMINANT-SP!CIFIC DEGREE OF CLEANV? CRITERIA
Aqua>;ic Life
Drinking Water Water Qualit.y Criteria a
MCLb c (Ug /1)
MCLG
(mg/l) (mg/l) Acute C~rcni::
'v Arsenic 0.050 0.050 360 190
Barium 1.0 1.5
Cadmium 0.010. 0.005 3.9(+) 1.1 (...)
Chromium (total) 0.12
+6 0.05 16 11
+3 -d 1,700 210
Copper 1.°d 1.3 18 12 (+)
Iron 0.3 1,000
Lead 0.050 0.020 82 3.2 (+)
Manganese 0.05
Mercury 0.002 , 0.003 2.4 0.012
Nickel 1,400 (...) 160(-)
Seler.ium 0.01 0.045 20 5.0
Silver 0.050 4.1(+)
Zinc 5.0 120 1:0
aClean Water Act; 40 CFR part 131, for protection of aquatic 1i:e. E?A,
Quality Criteria for Water 1986 (May 1986~; Hardness dependent cr:ter:a
listed at hardness = lOa mq/l Caco3' EPA, Ambient Water Quality Cri.':eria
for Nickel--1986 (September 1986). EPA, Ambient Water Quality Cri,:eria
forZinc--1987 (March 1987), EPA, Ambient Water Quality Criteria for
Selenium--1987 (September 1987).
bsafe Drinking .Water Act, 40 CFR Part 141, Subpart B.
cSafe Drinking Water Act, Federal Register, Vol. 50, No. 219,
November 13, 1985, p. 47022.
d
Secondary MCLs.
Note:
Hardness dependent; 100 mg/l CaCo3 equivalents value listed.
B-3
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