S u pe rf u n d P rog ra m
Proposed Plan f &*} W
-~ . . . . _ _ . . . -~ _ . -~ . , V^^^^.{? Colorado Department
Captain Jack Mill Superfund Site ^^°
CDPHE and EPA Announce Proposed Plan
This Proposed Plan identifies the Preferred Alternative for
remediation of the contaminated soils and surface water
discharges associated with the Captain Jack Mill (CJM)
Superfund Site along Left Hand Creek in Boulder County. In
addition, this Plan summarizes other cleanup alternatives that
were evaluated for use at this site. This document is issued by
the Colorado Department of Public Health and Environment
(CDPHE), the lead agency for site activities, and the U.S.
Environmental Protection Agency (EPA), the support agency.
CDPHE, in cooperation with EPA, will select a final remedy for
the site after considering all information submitted during the 30-
day public comment period. In addition, CDPHE, in consultation
with the EPA, may modify the Preferred Alternative or select
another response action presented in this Plan based on new
information or public comments. Therefore, the public is
encouraged to review and comment on all the alternatives
presented in this Proposed Plan.
This Proposed Plan summarizes information that can be found in
greater detail in the Remedial Investigation / Feasibility Study
(RI/FS) report and other documents contained in the
Administrative Record file. CDPHE and EPA encourage the
public to review these documents to gain a more complete
understanding of the site and the Superfund activities that have
been conducted.
The Preferred Alternative for cleaning up the Captain Jack
Site is a combination of Surface Contamination Sources
Alternative 2B (On-Site Consolidation Cell for Principal
Threat Waste and Capping) and Subsurface Contamination
Sources Alternative 3B (Bulkhead and Mine Pool Mitigation
at the Big Five Adit with Phased Successive Biochemical
Reactor Treatment as required).
Dates to remember:
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PUBLIC COMMENT PERIOD:
Monday June 16 - Tuesday July 15, 2008
CDPHE will accept written comments on the
Proposed Plan during the public comment
period. Submit comments to:
Angus Campbell, CDPHE
Hazardous Materials & Waste Management
4300 Cherry Creek Drive South
Denver, CO 80246-1530
anaus. campbell(8>state. co. us
Space for written comments is provided at
the end of the document. CDPHE will also
extend the public comment period by 30
days, upon reasonable and timely request.
PUBLIC MEETING: Wed July 2, 2008
CDPHE will hold a public meeting to explain
the Proposed Plan and all of the alternatives
presented in the Feasibility Study. Oral and
written comments will also be accepted at
the meeting. The meeting will be held at the
Ward Municipal Dojo Room at 6:00 p.m.
For more information, see the files at the
following locations:
Ward Public Library
Post Office / Town Hall Building
Ward, CO 80481
University of Colorado Public Library
1720 Pleasant Street, Boulder, CO 80309
Administrative Record at:
CDPHE
4300 Cherry Creek Drive South
Denver, CO 80246-1 530
303-692-2000
Hours: Mon-Fri, 8:30 a.m. to 5 p.m.
The Superfund Pipeline
Pre-Remedial
Response Process Remedial Response Process
• Preliminary Assessment / \ Remedial \ \ \ \
Qito Incno^tinn (^ 1 Investigation/ & Remedy 1 Remedial \ Remedial 1 Operations, \
. bite inspection L> Feasibility Study Selection Design Action Maintenance
• Placement on National y /(RI/FS) / (RD) /
-------
Proposed Plan (continued)
Photograph of Big Five Mine draining adit and waste pile at
Captain Jack Superfund Site
What are the "Contaminants of Concern"
CDPHE and the EPA have identified eight metals
that pose a risk to human health and the
environment at this site. Three of the metals;
arsenic, lead and thallium, present significant
human health risks, while antimony, arsenic,
cadmium, copper, zinc, and manganese present
risks primarily to fish and other aquatic life.
Antimony: Antimony in the soil ranges from "too
low to measure" to 10,800 milligrams per kilogram
(mg/kg). It has not been found in the surface
water. Antimony has both high acute and chronic
toxicity to aquatic life. Long term exposure has
shown to cause fertility problems in laboratory
animals.
Arsenic: Arsenic in the soil ranges from "too low
to measure" to 10,676 mg/kg. It has not been
found in the surface water. Arsenic can cause
cancer in humans, and has been linked to lung,
skin, bladder, liver, kidney and/or colon cancer.
Other effects include skin and nerve damage.
Cadmium: Cadmium, a toxic metal, exists in the
soil at the site in concentrations ranging from "too
low to measure" to 241 mg/kg. Cadmium in the
surface water ranges from "too low to measure" to
0.008 milligrams per liter (mg/L). Vegetables and
other plants absorb cadmium easily, and can be
extremely dangerous when eaten. Cadmium often
diminishes plant growth. Aquatic organisms can
vary greatly in their sensitivity to cadmium.
(continued on following page)
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dated 1967-1972; Revised from aerial photographs dated 1975-
1976, and 1978; UTM Zone 13, NAD 27.
Site History
The CJM Superfund Site is located near Ward, Colorado,
within the Left Hand Creek Watershed. In the 1980s, the
EPA discovered fisheries and wetlands impacts in the
watershed. These impacts were suspected to be associated
with discharges of metal-contaminated water from the major
abandoned mining and milling areas, including the CJM
site. On September 29, 2003, the CJM site was listed on
the National Priorities List (NPL).
Site Characteristics
A RI/FS was conducted between 2004 and 2008. The RI/FS
identified the types, quantities and locations of
contaminants and evaluated ways to address the
contamination problems. The RI/FS identified three main
mine and mill areas of contamination including The Big
Five, Captain Jack and White Raven. Approximately 85,000
cubic yards of contaminated waste rock, tailings and soil
were identified, which includes approximately 9,000 cubic
yards of material that is considered Principal Threat Waste.
In addition, up to 50 gallons per minute of metals-
contaminated water is draining from the Big Five Adit,
eventually flowing into Left Hand Creek.
The Rl found that:
• The main contamination comes from toxic metals in soil,
waste rock, tailings, surface water and mine impacted
groundwater.
• Contaminants of concern include: antimony, arsenic,
cadmium, copper, lead, manganese, thallium and zinc.
Page 2
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Proposed Plan (continued)
"Contaminants of Concern" (continued)
Copper: Copper in the soil ranges from 8 to
90,245 mg/kg. In the surface water, copper
ranges from "too low to measure" to 2.5 mg/L.
Copper in soil can harm microorganisms and
earthworms. At higher doses copper is toxic to
aquatic life.
Lead: Lead in the soil ranges from 27 to 177,000
mg/kg. In the surface water it ranges from "too
low to measure" to 0.016 mg/L. A highly toxic
element, lead causes a variety of health effects.
Brief exposure to high levels of lead can cause
brain and kidney damage and stomach or
intestinal distress. Long-term exposure to low
levels of lead can affect reproductive organs, the
central nervous system, blood pressure and
kidneys. Elevated lead levels stunt plant growth.
Manganese: Manganese in the soil ranges from
290 to 21,130 mg/kg. In the surface water it
ranges from "too low to measure" to 6.69 mg/L.
Long-term exposure to low levels of manganese
can result in central nervous system damage
while respiratory problems can occur from an
acute high exposure. Most plants have a very high
tolerance for manganese, but it is moderately
toxic to aquatic organisms.
Thallium: Thallium in the soil ranges from "too
low to measure" to 27.2 mg/kg. In the surface
water it ranges from "too low to measure" to 0.009
mg/L. At high exposure levels, thallium causes
nervous system disturbances. Long-term
exposure to low levels of thallium can cause
fatigue, headaches and depression because it
accumulates in the human body. Thallium is very
toxic to some rodents, and causes color changes
and stunted growth in plants.
Zinc: Zinc in the soil ranges from 66 to 217,510
mg/kg. In the surface water, it ranges from "too
low to measure" to 1.76 mg/L. Zinc is a trace
element essential for human and animal health.
At very high levels, zinc can cause arteriosclerosis
in humans. Aquatic organisms can accumulate
zinc and pass it to animals higher on the food
chain. In freshwater, high zinc levels have acute
effects and can be toxic to fish and other aquatic
life.
Sources of contamination include: the underground
mine-workings and ore-materials that release acid mine
drainage (AMD) from an open adit (entrance tunnel) at
the Big Five mine; and exposed waste rock and tailings
piles that leach and erode into the creek.
Scope and Role of the Action
The Remedial Action Objectives are to prevent current and
future exposure to contaminated soil, water and
groundwater through a combination of treatment and
containment. The remedial response actions described in
this Proposed Plan will permanently control and reduce the
toxicity, mobility and volume of those source materials that
pose a risk at the site. Site specific remedial action
objectives are discussed on page 5.
Summary of Site Risks
Left Hand Creek is a public water supply, although the
diversion is several miles downstream from the site. A
primary reason for listing this site on the NPL was the
potential for risks to the downstream public water supply,
either from continuous discharge from the adit or future
tunnel collapses that could cause large surges of AMD into
Left Hand Creek.
As part of the RI/FS, CDPHE and EPA conducted a
baseline risk assessment to determine the current and
future effects of contaminants on human health and the
environment. Residents currently reside onsite; therefore,
the baseline risk assessment focused on health risks for
children and adults in a residential setting resulting from
direct contact with contaminated soil and/or contaminated
water. CDPHE and EPA believe that the Preferred
Alternative identified in this Proposed Plan is necessary to
protect public health and the environment from actual or
threatened releases of hazardous substances.
Human Health Risks
A human health risk assessment was performed to describe
site-related risks to people who are exposed to
contaminants of concern. Some non-cancer and cancer
risks are elevated at the site. The risks are highest in the
Captain Jack Mill area. All site areas have the potential for
elevated non-cancer and cancer risks, if people come into
contact with contaminated soil or water. These risks are
much higher for residents than for other individuals.
Contaminated surface soil is the material most likely to
produce excess non-cancer or cancer risks. Eating garden
vegetables produced non-cancer hazard quotients (see box
on page four for an explanation of hazard quotients) as high
Page 3
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Proposed Plan (continued)
How Is Baseline Risk Calculated?
A Superfund human health risk assessment
calculates the "baseline risk," an estimate of the
likelihood of health problems occurring if no cleanup
action were taken at a site. To estimate the baseline
risk at a Superfund site, CDHPE and EPA undertake
a four-step process:
Step 1: Analyze Contamination
Step 2: Estimate Exposure
Step 3: Assess Potential Health Dangers
Step 4: Characterize Site Risk
In Step 1, CDPHE and EPA look at the
concentrations of contaminants found at a site as
well as past scientific studies on the effects these
contaminants have had on people (or animals, when
human studies are unavailable). Comparisons
between site-specific concentrations and
concentrations reported in past studies help
regulators determine which contaminants are most
likely to pose the greatest threat to human health.
In Step 2, CDPHE and EPA consider the different
ways people might be exposed to the contaminants
identified in Step 1, the concentrations people might
encounter, and the potential frequency and length of
exposure. Using this information, regulators calculate
a "reasonable maximum exposure" scenario,
which predicts the highest level of human exposure
that could reasonably be expected to occur.
In Step 3, CDPHE and EPA combine the information
from Step 2 with toxicity information for each
chemical to assess potential health risks. Regulators
consider two types of risk: cancer risk and non-
cancer risk. The likelihood of any kind of cancer
resulting from a Superfund site is expressed as an
upper-bound probability; for example, a "one in
10,000 chance." In other words, for every 10,000
people that could be exposed to site contaminants,
one extra cancer case may result. An extra cancer
case means that one more person could get cancer
than would be expected normally from all other
causes. For non-cancer health effects, regulators
calculate a "hazard quotient" (HQ). The key
concept here is that a "threshold level" (usually
measured as a hazard quotient of less than one)
exists below which non-cancer health effects are no
longer predicted.
In Step 4, CDPHE and EPA combine, evaluate and
summarize the results of the three previous steps to
determine whether site risks are great enough to
cause health problems for people at or near the
Superfund site. In this step, regulators add up the
potential risks to the individual.
as two and excess cancer risks as high as one in 2,300.
Using surface water as the sole drinking-water source
produced higher risk estimates than skin contact or
incidental use. Eating fish and drinking groundwater also
produced higher excess cancer risks.
Ecological Risks
An ecological risk assessment indicated that the aquatic
ecosystem is greatly impacted. Numerous metals in each
exposure area produced hazard quotients (HQs) greater
than one. The Captain Jack Mine (CJM) and Big Five
areas present the highest ecological risk. Bottom-dwelling
invertebrates were largely lacking during sampling events,
and fish populations appear reduced in the Left Hand
Creek through the site. The CJM area produced the
highest HQs for plants and land-dwelling invertebrates
exposed to surface soils. The Big Five area produced the
highest HQs for aquatic life exposed to surface water.
Swallowing surface soil would produce HQs greater than
one for all birds and mammals potentially exposed to
surface soil. Numerous metals had HQs above one for
birds and mammals. Lead produced the highest HQs for
birds, and arsenic produced the highest HQs for mammals.
The CJM area exhibited the highest HQs for birds and
mammals.
Only burrowing animals are expected to be exposed to
subsurface soil. Subsurface soils produced HQs greater
than one for the montane vole, and the highest HQ was 11
for aluminum at the CJM area.
There were no HQs greater than one for birds and
mammals drinking surface water, so using the stream as a
drinking water source is not likely to pose a risk to them.
All exposure areas present a potential risk to living things.
Soil, surface water and groundwater all produce HQs
greater than one for at least one group of organisms.
Surface water is potentially problematic for aquatic life. The
CJM and Big Five areas present the highest ecological
risk.
Page 4
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Proposed Plan (continued)
Remedial Action Objectives (RAOs)
The Remedial Action Objectives (RAOs) are:
• So/7s, Tailings and Waste Rock:
1) Reduce exposure to the Principal Threat Wastes —
arsenic, lead and thallium — from incidental
swallowing and/or breathing of surface
tailings/waste rock and other mine wastes; and
2) Control and/or reduce water run-on and runoff from
soils/tailings/waste rock piles.
• Surface Water:
1) Reduce in-stream metals concentrations;
2) Ensure that in-stream metals concentrations do not
degrade drinking water supplies diverted from Left
Hand Creek; and
3) Reduce the toxicity to bottom-dwelling aquatic
organisms living in or just above the sediment to
levels that protect aquatic life.
What is Principal Threat Waste?
Principal Threat Wastes are source materials
that are highly mobile or highly toxic that
cannot be reliably contained. Should exposure
occur, they would present a significant risk to
human health or environment. At the Captain
Jack Mill site, lead, arsenic and thallium are the
Principal Threat Wastes.
For the Captain Jack site Principal Threat
Waste is defined as solid material which
contains lead concentrations exceeding 1,460
mg/kg (based on the CDPHE Hazardous
Materials and Waste Management Division Soil
Cleanup Table Value Standard [TVS] for
Industrial Land Use). The value of 1,460 mg/kg
was derived through exposure modeling
performed by CDPHE in an attempt to
determine the most appropriate risk-based
threshold for industrial land use, which is an
appropriate land use for mining sites.
Management of this material exceeding the
threshold level is described in the remedial
alternatives. Because arsenic and thallium are
typically co-located with lead, lead was
selected as the definitive metal for this
classification.
Groundwater:
1) Control and/or reduce metals loading to
groundwater from subsurface and surface sources
to ensure that contaminated groundwater does not
harm human health or result in releases that impair
organisms living in Left Hand Creek.
The RAOs will be achieved by reducing the mobility of
the contaminants in the soil and waste rock.
Isolation/containment and capping the waste will
prevent exposure to the materials.
Cleanup activities are triggered by a contaminant-
specific and location-specific "Remedial Action Level."
Table 1 presents these values. Priority will be given to
the Principal Threat Wastes, which are considered the
most dangerous contaminants of concern, either due to
their concentration in the environment or other physical
characteristics.
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Definition of Contaminated Material
Arsenic
Thallium
85
5.2
Lead (by Exposure Area)
Big Five to CJM
Big Five
CJM
White Raven
White Raven to
Sawmill
860
830
380
400
750
Page 5
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Proposed Plan (continued)
Summary of Remedial Alternatives
Remedial alternatives for the site appear below. The alternatives are numbered to correspond with the numbers
in the RI/FS Report. Alternatives have been separated into surface contamination sources alternatives and
subsurface contamination sources alternatives. To meet Remedial Action Objectives (RAOs) for the site, two
alternatives should be selected: one from the surface contamination sources group, and one from the
subsurface contamination sources group.
The following remedial alternatives have been developed for the site.
• Alternative 1: No Action
Surface Contamination Sources Alternatives:
• Alternative 2A: Off-Site Disposal of Principal Threat Waste with Remainder Cap-in-Place
• Alternative 2B: On-Site Consolidation & Capped-Cell for Principal Threat Waste with Remainder Cap-
in-Place
• Alternative 2C: On-Site Consolidation & Capped-Cells for Contaminated Soils
Subsurface Contamination Sources Alternatives (Big-Five Adit):
• Alternative 3A: Bulkhead with Monitoring
• Alternative 3B: Bulkhead and Internal Mine-Pool Mitigation with Phased Successive Biochemical
Reactor Treatment Outside of Adit
• Alternative 3C: Neutralization and Biochemical Reactor Treatment of Big Five AMD Outside of Adit
• Alternative 3D: Outside-Adit Water Treatment System for Big Five AMD
Alternative 1: NO ACTION
Superfund regulations require the "no action"
alternative to be evaluated to establish a baseline
for comparison. Under this alternative, no action
would be taken at the site to prevent exposure to
contaminated soil and groundwater.
Estimated Capital Cost: $0
Estimated Remedial Action Cost: $0
Estimated Present-Worth Cost: $0
Surface Contamination Sources
Alternatives:
Alternative 2A: OFF-SITE DISPOSAL OF
PRINCIPAL THREAT WASTE AND CAPPING
Estimated Design and Construction Cost:
$2,368,986
Estimated Total O&M Present-Worth Cost: $27,700
Estimated Present-Worth Cost: $2,396,700
Removing Principal Threat Waste to an off-site
facility requires the following basic steps:
• Excavate Principal Threat Waste;
• Remove excavated waste to an off-site landfill;
• Cap the remaining contaminated materials in
place - materials that exceed the remedial
action levels defined in Table 1 but which
contain lead concentrations less than 1,460
mg/kg (see Figure 1 and Table 1);
• Divert surface water runoff during excavation
and capping, and for purposes of permanent
control; and
• Implement access controls such as
fencing/signage and/or Institutional Controls to
prevent or minimize activities that could
jeopardize remedial components.
The Principal Threat Waste is located primarily at
the Big Five to CJM area, CJM, White Raven, and
White Raven to Sawmill areas. There are
approximately 9,000 cubic yards (cy) of this waste
(see Figure 1).
Page 6
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Proposed Plan (continued)
Figure 1: Surface Contamination Sources Alternatives
CAPPING SCENARIOS
1. CAP FOR MATERIAL
REMAINING IN PLACE
BIG FIVE AREA
BIG FIVE to CAPTAIN
^X JACK AREA
VEGETATION
/6-INCHES
' GROWTH MEDIA
f 12-INCHES
SELECT FILL
/ LIME MIXED
_ INTO TOP 6-
_ INCHES OF
WASTE
WASTE
MATERIAL
2. CAP FOR PRINCIPAL THREAT
WASTE IN CONSOLIDATION CELLS
VEGETATION
6-INCHES GROWTH MEDIA
12-INCHES SELECT FILL
EOSYNTHETIC CLAY LINER
LIME MIXED INTO TOP 6-INCHES OF
WASTE
DEPTH OF WASTE MATERIAL VARIES
CAPTAIN JACK MILL AREA
WHITE RAVEN
AREA
r-—| MINE DUMP
I " I CREEK
J UNPAVED ROAD
* PAVED ROAD
BUILDING
AREA BOUNDARY
] MATERIAL CONTAMINATED
WITH LEAD
I MATERIAL CONTAMINATED
WITH THALLIUM
^ MATERIAL CONTAMINATED
WITH ARSENIC
PRINCIPAL THREAT WASTE
WHITE RAVEN to
XSAWMILL AREA
Because a single-vehicle road is the only access to
the site, road improvements will be required for this
alternative. Excavation around existing structures
can likely be accomplished.
Two commercial landfills were identified within 60
to 70 miles from the site. The first is the North Weld
County Landfill in Ault, Colorado, and the second is
the CSI Landfill in Bennett, Colorado. The CSI
Landfill will most likely have the capacity for the
waste removed from this site. Material that is
determined to be hazardous, and which CSI Landfill
is unable to accept, could be transported to Clean
Harbors Deer Trail, LLC (known as the Highway 36
Landfill) for stabilization and burial.
Alternative 2B: ON-SITE CONSOLIDATION
CELL FOR PRINCIPAL THREAT WASTE AND
CAPPING
Estimated Design and Construction Cost:
$1,067,637
Estimated Total O&M Present-Worth Cost:
$276,580
Estimated Present-Worth Cost: $1,344,200
This alternative differs from Alternative 2A in that
Principal Threat Waste is excavated and placed in
an on-site consolidation cell instead of being
removed to an off-site disposal facility. The on-site
consolidation cell would potentially be located at
Page 7
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Proposed Plan (continued)
the CJM site along the scarred surface bordering
the former tailings ponds on the northeast. The
material currently in the former tailings ponds would
not be excavated and therefore would become part
of the cell. Approximately 5,050 cubic yards (cy) of
waste material from all five areas of contamination
at the site would be placed in the cell and
compacted.
The cell cap likely would consist of six inches of
topsoil on top of 12 inches of select fill, on top of a
geosynthetic clay liner. Before the liner is placed,
caustic material would be mixed into the top six
inches of the waste material to neutralize waste
and to minimize acidic leaching. The liner provides
a barrier between the waste material and the upper
cap layers and prevents clean water from seeping
into the underlying waste material. Plants on top of
the cover would require annual maintenance and
may require reseeding several times within the first
few years. A crushed-rock apron or cap layer also
may be considered to keep rodents from burrowing
into the cap. Project officials expect capping and
erosion-protection materials to be available within a
three- to four-acre borrow area near the site. The
specific location for the cell would be fully evaluated
during the design phase, including evaluation of the
borrow area adjacent to the CJM and the alluvial
valley above the Big Five tunnel.
Potential area for on-site consolidation cell at CJM area.
Related work would include design and oversight;
mobilization; minor road improvements; site
grading; drainage systems and erosion control; and
demobilization.
Alternative 2C: ON-SITE CONSOLIDATION
CELLS FOR CONTAMINATED SOILS
Estimated Design and Construction Cost:
$1,066,920
Estimated Total O&M Present-Worth Cost:
$182,602
Estimated Present-Worth Cost: $1,249,500
This alternative is similar to Alternative 2B in that
material is placed in an on-site cell. The primary
difference is that all waste is excavated and placed
in several cells instead of solely the Principal
Threat Waste. Under this alternative, the following
areas would be excavated:
• 90 cy of waste from the Big Five area;
• 620 cy of waste from the Big Five to CJM area;
• 17,500 cy from the CJM area;
• 15,500 cy from the White Raven area; and
• 260 cy from the White Raven to Sawmill area.
(Please note that these quantities do not add up to
the 85,000 cy of material discussed on page 2 as
approximately 51,000 cy of material is already in
place in the proposed consolidation cell areas and
would not require excavation.)
All of these materials would be placed in on-site
consolidation cells (most likely three cells) within
the CJM and White Raven areas.
The cell cap likely would consist of six inches of
topsoil, on top of 12 inches of select fill, on top of a
clay liner. Before the liner is placed, caustic
material would be mixed into the top six inches of
the waste material to neutralize waste and to
minimize acidic leaching. The liner provides a
barrier between the waste material and the upper
cap layers and prevents clean water from seeping
into the underlying waste material. Plants on top of
the cover would require annual maintenance and
may require reseeding several times within the first
few years. A crushed-rock apron or cap layer also
may be considered to keep rodents from burrowing
into the cap. Project officials expect capping and
erosion-protection materials to be available within a
three- to four-acre borrow area near the site. The
specific location for the cells would be fully
evaluated during the design phase. Location
options include the borrow area adjacent to the
CJM and the alluvial valley above the Big Five
tunnel.
PageS
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Proposed Plan (continued)
Related work would include design and oversight;
mobilization; minor road improvements; site
grading; drainage systems and erosion control; and
demobilization.
What type of access restrictions will remain in
place at the site?
Temporary fencing will be necessary throughout
construction of any of the alternatives. In addition,
temporary fencing will be maintained around newly
capped areas for a period of time sufficient to allow
new vegetation to take hold. The consolidation
cell(s) would be fenced to maintain the integrity of
the cap. Access to these particular areas would be
permanently restricted.
Subsurface Contamination Sources
Alternatives:
Alternative 3A: BIG FIVE ADIT BULKHEAD
WITH MONITORING
Estimated Design and Construction Cost:
$1,866,755
Estimated Total O&M Present-Worth Cost:
$1,478,394
Estimated Present-Worth Cost: $3,345,100
This alternative addresses the Acid Mine Drainage
(AMD) from the Big Five adit in an effort to meet the
RAOs. Based on an examination of the Big Five
adit, a concrete plug called a "bulkhead" could be
installed approximately 470 to 675 feet from the
portal. The bulkhead would consist of a concrete
structure approximately 10 feet thick.
Water would back up behind the "plug," and
underground mine workings would partially flood.
The surrounding area would be closely monitored
to detect water leaking out of the underground
workings through seeps or previously unknown
openings. The bulkhead would have a pressure
gauge and flow-through valve to monitor water in
the tunnel and maintain it at an optimum level.
The alternative is designed to decrease the amount
of oxygen in the open mine workings by flooding,
which will reduce the formation of toxic AMD and in
addition will help contain AMD that is generated and
entering Left Hand Creek.
Alternative 3B: BIG FIVE ADIT BULKHEAD AND
MINE POOL MITIGATION WITH PHASED
SUCCESSIVE BIOCHEMICAL REACTOR
TREATMENT AS REQUIRED
Phase One:
Estimated Design and Construction Cost:
$2,968,827
Estimated Total O&M Present-Worth Cost:
$854,858
Estimated Present-Worth Cost: $3,823,700
Phase Two:
Estimated Design and Construction Cost:
$2,166,549
Estimated Total O&M Present-Worth Cost:
$4,408,065
Estimated Present-Worth Cost: $6,574,600
This alternative begins with the bulkhead described
in Alternative 3A and, during the first phase, treats
acidic water inside the mine through a process
called "in-situ mine-pool neutralization."
By installing this bulkhead, water would back up
behind the "plug" and underground mine workings
would partially flood. The surrounding area would be
closely monitored to detect and observe areas
where water could "leak" out of the underground
workings through seeps or other unknown openings.
The bulkhead would have a pressure gauge and
valve to monitor and manage the water in the tunnel
at an optimum level that allows for the best
management practices for the remedy.
As acidic water builds up behind the bulkhead, wells
will inject and circulate sodium hydroxide or another
caustic chemical into the mine pool. The chemical
reaction would raise the pH of the underground
water, making it more alkaline. As the alkalinity
rises, some of the dissolved metals will change to a
solid form and sink to the bottom of the tunnel.
During mine-pool neutralization, surface water will
be monitored to assess the water quality of Left
Hand Creek. If the mine-pool treatment appears to
have stabilized enough to support bacterial growth
after approximately two years of neutralization, but
downstream RAOs are not being met for surface
water, the second phase of this alternative will be
evaluated. If downstream RAOs are being met for
surface water, and monitoring indicates that AMD
waters within the mine pool and groundwater
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Proposed Plan (continued)
reservoir are being fully controlled, project officials
will consider not implementing the second phase.
The second phase of this alternative involves
installing a series of vessels called "biochemical
reactors" on the flat area immediately outside of the
adit atop the waste dump and/or at the base of the
Big Five pile. The reactors use microorganisms to
transform hazardous contaminants into
nonhazardous substances. The process forms non-
toxic metal sulfides, effectively reducing the mobility
of copper, lead, zinc, and cadmium in AMD.
After the biochemical reactor treatment, water
would flow through on-site wetlands for a "polishing
treatment" before draining to Left Hand Creek.
The biochemical reactor designed would depend on
"pre-treated" conditions of the mine-pool water, and
would require detailed bench- and/or pilot-scale
studies. These studies would determine the best
vessel size, organic material and need for
additional treatment.
Like other remedial components, biochemical
reactors would require site-access restrictions. The
Example of biochemical reactor at the Leviathan mine in California.
process would produce small amounts of a
hazardous, but easily dispersed hydrogen sulfide
gas that may require management. CDPHE will
monitor the release to ensure that it doesn't cause
public health effects. In addition, the treatment
system would require operation and maintenance
to assess effectiveness, replenish organic materials
and/or perform repairs. Road improvements and
on-site monitoring controls would be necessary.
Alternative 3C: BIG FIVE ADIT BULKHEAD
WITH ABOVE GROUND NEUTRALIZATION AND
BIOCHEMICAL REACTOR TREATMENT OF
DRAINAGE
Estimated Design and Construction Cost:
$4,442,305
Estimated Total O&M Present-Worth Cost:
$6,576,647
Estimated Present- Worth Cost: $11,019,000
This alternative is similar to Alternative 3B. It
involves AMD-neutralization and biochemical
reactors; however, the alternative differs significantly
from 3B in that there is only one phase to this
alternative. Instead of neutralizing acid water inside
the mine, a neutralization/precipitation system would
be built outside of the adit, along with the
biochemical reactors. A bulkhead would be installed
to control flow rates and restrict oxygen in the mine;
however, neutralization of the acidic drainage would
take place outside of the mine tunnel in
neutralization and settling ponds.
As with the second phase of Alternative 3B, the
biochemical reactors would require site access
restrictions and operation and maintenance.
Ongoing maintenance would most likely be more
intensive under this alternative, because sludge
management will be required for metal generated in
the neutralization process and/or settling ponds.
Sludge management would not be necessary with
the in-situ mine pool neutralization of Alternatives 3A
and 3B.
Alternative 3D: BIG FIVE ADIT BULKHEAD
WITH PRECIPITATION WATER TREATMENT
SYSTEM FOR DRAINAGE
Estimated Design and Construction Cost:
$4,496,174
Estimated Total O&M Present-Worth Cost:
$15,250,515
Estimated Present-Worth Cost: $19,746,700
This alternative involves a bulkhead similar to that
proposed in Alternative 3A. However, the
remainder of the alternative is vastly different than
those previously presented because it involves a
full-scale, active water treatment plant for the water
exiting the bulkhead's flow-through valve.
Several active processes would treat the adit water:
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Proposed Plan (continued)
• Precipitation is chemically similar to the
process described in Alternatives 3B and
3C, but happens at the treatment plant.
Raising the alkalinity of the AMD water
creates a chemical change in the dissolved
metal, causing it to solidify and settle to the
bottom of the tank. The precipitation
treatment would be expected to remove
most of the metals of concern (cadmium,
copper and zinc).
• Filtration would involve the use of
mechanical filters and presses to remove
the metals and sludges, which would have
to be disposed of in an on-site consolidation
cell or an off-site landfill.
• Immobilized Ligand Treatment may be
required. A ligand is an atom or molecule
that bonds to a metal. One such treatment
would use iron salts to create a bond with
arsenic, allowing it to be removed from the
contaminated water.
• Polymer Addition would remove any
remaining metals and further increase the
alkalinity of the water before it is discharged
into Left Hand Creek. A polymer is a natural
or artificial chemical made up of smaller,
identical molecules linked together.
Polymers have high molecular weights, and
are used for a variety of industrial
processes.
A treatability study would need to be performed on
the adit discharge water to select the specific
polymer and base required. The treatability study
would also be necessary to determine if an
additional immobilized ligand treatment system is
appropriate. Continuous operation and
maintenance would be required for this system.
Evaluation of Alternatives
Nine criteria are used to evaluate the different remediation alternatives individually and against each other to
select a remedy. This section describes the relative performance of each alternative against the nine criteria,
noting how it compares to the other options under consideration. The nine evaluation criteria are discussed on
the following page. The "Detailed Analysis of Alternatives" can be found in the FS.
EVALUATION CRITERIA FOR SUPERFUND REMEDIAL ALTERNATIVES
Protectiveness of Human Health and the Environment determines whether an alternative eliminates, reduces, or
controls threats to public health and the environment through institutional controls, engineering controls, or treatment.
Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) evaluates whether the
alternative meets federal and state environmental statutes, regulations, and other requirements that relate to the site, or
whether a waiver is justified.
Long-term Effectiveness and Permanence considers the ability of an alternative to maintain protection of human
health and the environment overtime.
Reduction of Toxicity, Mobility, or Volume of Contaminants through Treatment evaluates an alternative's use of
treatment to reduce the harmful effects of principal contaminants, their ability to move in the environment, and the
amount of contamination present.
Short-term Effectiveness considers the length of time needed to implement an alternative and the risks the alternative
poses to workers, residents, and the environment during implementation.
Implementability considers the technical and administrative feasibility of implementing the alternative, including factors
such as the relative availability of goods and services, including the reliability of Institutional Controls.
Cost includes estimated capital and annual operations and maintenance costs, as well as present worth cost. Present
worth cost is the total cost of an alternative overtime in terms of today's dollar value. Cost estimates are expected to be
accurate within a range of+50 to -30 percent.
State/Support Agency Acceptance considers whether CDPHE agrees with EPA's analyses and recommendations, as
described in the RI/FS and Proposed Plan.
Community Acceptance considers whether the local community agrees with CDPHE's analyses and preferred
alternative. Comments received on the Proposed Plan are an important indicator of community acceptance.
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Proposed Plan (continued)
1. Overall Protection of Human Health and the
Environment
No Action Alternative:
Alternative 1 does not provide adequate protection
of human health and/or the environment.
Surface Contamination Sources Alternatives:
All three surface contamination sources alternatives
(2A, 2B and 2C) would protect both human health
and the environment. The consolidation of Principal
Threat Waste in on-site consolidation cells or an
off-site disposal facility would significantly reduce
and/or eliminate human health risks from exposure
to surface waste.
Subsurface Contamination Sources Alternatives:
All subsurface contamination sources alternatives
(3A, 3B, 3C and 3D) significantly reduce the
movement of contaminants from the Big Five adit to
the waters of Left Hand Creek, and therefore would
reduce, but not eliminate potential human health
risks from surface and groundwater affected by the
underground mine water.
Alternative 3A may ultimately be less protective of
human health and the environment, because it
does not include AMD treatment.
Alternative 3B, Phase I would partially reduce the
risk to human health and the environment through
in-situ neutralization of the mine pool. However,
unknown hydraulic conditions of the mine pool
reservoir add uncertainty to this phase of the
alternative.
Alternative 3B, Phase II and Alternative 3C will
protect human health and the environment.
Alternative 3D would likely be most protective of
human health and the environment because a fully
active treatment system would have the flexibility to
adapt quickly to changing water-quality conditions
and to add additional treatment components if
needed.
2. Compliance with Applicable or Relevant and
Appropriate Requirements (ARARs)
No Action Alternative:
It is unknown whether Alternative 1 would ultimately
comply with ARARs, given that no monitoring is
provided. However, it is highly unlikely.
Surface Contamination Sources Alternatives:
Alternatives 2A, 2B and 2C would all comply with
ARARs by providing moderate to high levels of
containment of waste material on- and/or off-site.
Subsurface Contamination Source
Alternatives:
Alternative 3A may be able to comply with ARARs;
however, because seepage volume and potential
locations are unknown and the quality of any water
that may or may not seep from the plugged tunnel
is unknown, it is impossible to state that this
alternative will comply with all ARARs at the site.
Treatability studies would be required to determine
whether Alternatives 3B, 3C and 3D would comply
with chemical-specific ARARs; however, based on
the water quality of the Big Five adit drainage and
the efficiency of the biochemical reactor and
precipitation processes, these alternatives would be
considered capable of meeting chemical-specific
ARARs if properly designed and operated.
Alternative 3B, Phase I could potentially comply
with ARARs, but will depend upon the response of
the "natural containment system." If the mine
workings form a tight underground reservoir with
minimal seepage to the surrounding area, in-situ
neutralization and natural attenuation could
potentially help the alternative achieve chemical-
specific ARARs. However, if Phase I is not effective
in meeting ARARs, Alternative 3B, Phase II would
need to be implemented, and would very likely
achieve ARARs.
3. Long-Term Effectiveness and Permanence
No Action Alternative:
Alternative 1 would not implement any controls and
significant concerns about residual effects would
remain.
Surface Contamination Sources Alternatives:
All three alternatives are proposed long-term
solutions with no concerns about residual effects.
Principal Threat Waste would be contained in all
alternatives and exposure to plants, animals and
humans would be prevented.
Subsurface Contamination Sources Alternatives:
The actual bulkhead component of all alternatives
would have long-term permanence and
effectiveness because the concrete would
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Proposed Plan (continued)
deteriorate very slowly, and corrosion-resistant
stainless-steel or plastic piping would be used.
Because of some uncertainty about how the Big
Five adit connects with potential bedrock fractures
and other mine workings in the region, groundwater
discharges and/or releases from other locations may
occur. Area monitoring would be required to
accurately assess the effectiveness of the bulkhead,
along with assessments of the elevation, location
and geochemical conditions of the mine pool.
Alternatives 3B, 3C and 3D also are likely to be
effective in the long term, as long as treatment
systems are maintained. As discussed previously,
water-quality monitoring would be required to
assess the long-term effectiveness of the first phase
of Alternative 3B to ascertain the need to implement
the second phase. The timing of the decision to
implement Phase II will depend on the response of
the in-situ system and the downstream monitoring
data. Project officials expect the decision to be
made within the first year or two after installation of
Phase I.
4. Reduction of Toxicity, Mobility or Volume
No Action Alternative:
Alternative 1 would not reduce toxicity, mobility or
volume of contaminants, because no treatment is
specified.
Surface Contamination Sources Alternatives:
Limited treatment (addition of lime as a neutralizing
agent in the upper portion of the capped waste) is
included in this alternative, which reduces the
toxicity of the contaminants. Implementing any of
the alternatives would partially eliminate or contain
contaminated surface material, reducing their
movement. In addition, Alternative 2A would reduce
the volume of contaminated surface material at the
site.
Subsurface Contamination Sources Alternatives:
Implementation of any of the four alternatives would
reduce contaminant mobility and volume of AMD
flowing into Left Hand Creek. Alternative 3A would
primarily reduce the mobility of adit water and its
associated contaminants; however, the extent of
containment is uncertain.
Alternative 3B also would reduce contaminant
mobility, and would reduce the toxicity and mass-
loading of contaminants because it includes
treatment. In addition, if containment/treatment is
not achieved with mine-pool mitigation measures,
contaminant toxicity, mobility and volume would be
significantly reduced by additional treatment in the
biochemical reactor.
Alternative 3C would be similar to Alternative 3B in
reduction of contaminant toxicity, mobility and
volume.
Alternative 3D also would significantly reduce
contaminant toxicity, mobility and volume because
it involves an active treatment system.
5. Short-Term Effectiveness
No Action Alternative:
Alternative 1 would not be effective in the short
term.
Surface Contamination Sources Alternatives:
With the use of engineering controls, all three
alternatives would provide short-term effectiveness.
Risks to workers, residents and the environment
would be minimal during construction.
Subsurface Contamination Sources Alternatives:
As with the surface contamination sources
alternatives, all four alternatives would provide
short-term effectiveness. If properly designed and
constructed, risks to workers, residents and the
environment would be minimal for any of the
alternatives.
6. Implementability
No Action Alternative:
Alternative 1 would be easy to implement because
it requires no action.
Surface Contamination Sources Alternatives:
All three alternatives would be implementable.
However, Alternative 2A may pose technical
difficulties associated with access and
transportation of waste from the site, and
Alternative 2C may pose additional technical
difficulties associated with excavation of all
contaminated material (rather than just Principal
Threat Waste) and construction of multiple
consolidation cells.
All three alternatives would be administratively
feasible and would involve coordination with other
offices and agencies. Because much of the land in
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Proposed Plan (continued)
the Captain Jack site is on private property,
permanent and enforceable arrangements with
landowners will ensure access, easements and
environmental covenants that are necessary for
long-term effectiveness and permanence of the
selected alternative. The required personnel,
services and equipment would be readily available.
Subsurface Contamination Sources Alternatives:
Bulkhead installation (a component of all four
alternatives) could be achieved, and has been
implemented at numerous sites. This component of
the alternatives would require well-qualified design
engineering and construction personnel with
extensive experience in evaluating the geotechnical
conditions of underground adits.
Alternative 3B presents the challenge of locating
injection and extraction wells into the mine pool and
successfully treating AMD in place. Although this
in-situ neutralization approach is relatively new, the
treatment technology is reliable and easily
understood. Phase II of this alternative - installing a
biochemical reactor at a mine site - is not yet
routine; however, it is becoming better developed.
Several successful biochemical reactors have been
installed at sites throughout the United States.
Alternative 3C also would be implementable
according to the same parameters discussed in
Alternative 3B. However, sludge management and
disposal would create a challenge. Road
improvements would be needed to make off-site
sludge disposal practical. Additional acreage would
likely be required for neutralization and/or settling
ponds. Building those ponds most likely would
require changes to the wetland areas.
Alternative 3D also would be implementable, and
would greatly benefit from a treatability study prior
to construction. Because the alternative is designed
as an active water-treatment option, road
improvements would be required to maintain year-
round access. Sludge removal and maintenance
would remain a challenge, similar to Alternative 3C.
7. Cost
The following present worth costs are estimated for
the alternatives:
No Action Alternative:
Alternative 1: $0
Surface Contamination Sources Alternatives:
Alternative 2A: $2,396,700
Alternative 2B: $1,344,200
Alternative 2C: $1,249,500
Subsurface Contamination Sources Alternatives:
Alternative 3A: $3,345,100
Alternative 3B: $10,398,300 (both phases)
Alternative 3C: $11,019,000
Alternative 3D: $19,746,700
8. Support Agency Acceptance
The EPA and CDPHE have worked closely in the
development of this document. EPA and CDPHE
both support the preferred alternative.
9. Community Acceptance
Community acceptance of the preferred alternative
will be evaluated after the public comment period
ends and will be described in the Record of
Decision (ROD) for the site.
Summary of the Preferred Alternative
The Preferred Alternative for cleaning up the
Captain Jack Site is a combination of Surface
Contamination Sources Alternative 2B (On-Site
Consolidation Cell for Principal Threat Waste and
Capping) and Subsurface Contamination Sources
Alternative 3B (Bulkhead and Mine Pool Mitigation
at the Big Five Adit with Phased Successive
Biochemical Reactor Treatment as required).
The preferred surface contamination source
alternative was selected over other alternatives
because it:
• Is expected to achieve substantial and long-
term risk reduction,
• Is implementable, given site conditions,
• Requires minimal maintenance of one major
consolidation cell,
• Specifically addresses Principal Threat
Waste, and
• Is cost-effective.
The preferred subsurface contamination source
alternative was selected because it:
• Allows flexibility in phased implementation,
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Proposed Plan (continued)
• Allows for in-situ neutralization of AMD,
• Avoids costly and labor-intensive sludge-
management issues,
• Utilizes a semi-passive treatment system
(biochemical reactor), and
• Is cost-effective.
Based on the information available at this time,
CDPHE and EPA believe the Preferred Alternative
would protect human health and the environment,
would comply with ARARs, would be cost-effective,
and would use permanent solutions and alternative
treatment technologies to the maximum extent
practicable. Because it would treat the source
materials constituting principal threats, the remedy
also would meet the statutory preference for the
selection of a remedy that involves treatment as a
principal element.
The Preferred Alternative can change in response
to public comment or new information.
Community Participation
CDPHE and EPA provide information regarding the
cleanup of the Captain Jack site to the public
through public meetings, the Administrative Record
at the Information Repository, and announcements
published in the Boulder Daily Camera, Denver
Post, and the Nederland Mountain-Ear. CDPHE
and EPA encourage the public to gain a more
comprehensive understanding of the site and the
Superfund activities that have been conducted at
the site.
The dates for the public comment period, the date,
location, time of the public meeting, and the
locations of the Administrative Record files are
provided on the front page of this Proposed Plan.
For further information, or to request a 30-day
public comment period extension, please contact:
Mr. Angus Campbell
Project Manager
CDPHE
Hazardous Materials Waste Management Division
4300 Cherry Creek Drive South
Denver, CO 80246-1530
(303) 692-3385
Email: angus. campbell@state. co. us
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Proposed Plan (continued)
0
Glossary of Terms
Specialized terms used in this Proposed Plan are defined below:
Acid Mine Drainage (AMD) - water with a low pH draining from mines, usually caused by the oxidation of
sulfides.
Adit-a nearly horizontal entrance into a mine.
Applicable or relevant and appropriate requirements (ARARs) - the Federal and State environmental laws
that a selected remedy will meet. These requirements may vary among sites and alternatives.
Biochemical Reactors - treatment systems that utilize microorganisms to transform or alter, through
metabolic or enzymatic action, hazardous contaminants into non-hazardous substances.
Consolidation Cell - an area in which waste material is placed and compacted for long-term disposal.
Capping systems are designed and placed over the top of consolidation cells to prevent exposure to the
underlying waste material.
Ex situ - the removal of a medium (for example, soil) from its original place, as through excavation, in order to
perform the remedial action.
Groundwater - underground water that fills pores in soils or openings in rocks to the point of saturation.
Groundwater is often used as a source of drinking water via municipal or domestic wells.
In situ - the treatment of a medium (for example, water) in its original place, in order to perform the remedial
action.
Institutional Controls - mechanisms, such as legal controls, fences and warning signs that reduce the
potential for human exposure to contamination left in place at a hazardous materials site.
Monitoring - ongoing collection of information about the environment that helps gauge the effectiveness of a
clean-up action.
Natural Attenuation - the reduction in mass or concentration of a compound in groundwater over time or
distance from the source because of naturally occurring physical, chemical and biological processes.
Neutralization - a chemical reaction between an acid and a base. In this plan, neutralization involves the
changing of an acid solution to neutral by addition of an alkaline solution.
Polymer - a natural or artificial chemical made up of smaller, identical molecules linked together. Polymers
have high molecular weights, and would be used in this plan for treating water contaminated with metals.
Preferred Alternative - the cleanup approach recommended by CDPHE and EPA, based upon how well it
meets the nine criteria used to evaluate remediation alternatives.
Present Worth Analysis - a method of evaluation of expenditures that occur over different time periods. By
discounting all costs to a common base year, the costs for different remedial action alternatives can be
compared on the basis of a single figure for each alternative. When calculating present worth cost for
Superfund sites, total operations and maintenance costs are to be included.
Record of Decision - a public document explaining which remediation alternative will be used at an NPL site.
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Proposed Plan (continued) ||_
Remedial Investigation / Feasibility Study (RI/FS) - investigative and analytical studies usually performed at
the same time in an interactive process. The studies are intended to: gather the data necessary to determine
the extent of the contamination; establish criteria for cleaning up the site; identify cleanup alternatives; and
analyze the technology and costs of each alternative.
Revegetate - to replace topsoil, seed, and mulch on prepared soil to prevent wind and water erosion.
Treatability Studies - where a remedial alternative cannot predict the specific results of a treatment
approach, a treatability study is performed to test various methods on a small scale (for example, in a
laboratory) prior to construction on the site.
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Proposed Plan (continued) ||_
USE THIS SPACE TO WRITE YOUR COMMENTS
Your input on the Proposed Plan for the Captain Jack Site is important to CDPHE and EPA. Comments
provided by the public are valuable in helping CDPHE and EPA select a final cleanup remedy for the site.
You may use the space below to write your comments, then fold and mail. Comments must be postmarked by
July 22, 2008. If you have any questions about the comment period, please contact Angus Campbell at 303-
692-3385 or through CDPHE's main number at 303-692-2000. You may submit comments to CDPHE at the
following e-mail address: ana us. campbell@)state. co. us. Address mailed comments to: Mr. Angus Campbell,
Project Manager, Colorado Department of Public Health and Environment, Hazardous Materials Waste
Management Division, 4300 Cherry Creek Drive South, Denver, CO 80246-1530.
Name
Address
City State Zip
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