National Oil and Hazardous Substance Pollution Contingency Plan: Partial Deletion of the California Gulch Superfund Site National Priorities List, 47007-47015 [2014-18955]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 79, Number 155 (Tuesday, August 12, 2014)]
[Rules and Regulations]
[Pages 47007-47015]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-18955]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 300

[EPA-HQ-SFUND-1983-0002; FRL 9914-92-Region 8]


National Oil and Hazardous Substance Pollution Contingency Plan: 
Partial Deletion of the California Gulch Superfund Site National 
Priorities List

AGENCY: Environmental Protection Agency.

ACTION: Direct final rule.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) Region 8 is 
publishing a direct final Notice of Partial Deletion of Operable Unit 
4, (OU4) Upper California Gulch; Operable Unit 5 (OU5), ASARCO 
Smelters/Slag/Mill Sites; and Operable Unit 7 (OU7), Apache Tailing 
Impoundment, of the California Gulch Superfund Site (Site), located in 
Lake County, Colorado, from the National Priorities List (NPL). The 
NPL, promulgated pursuant to section 105 of the Comprehensive 
Environmental Response, Compensation, and Liability Act (CERCLA) of 
1980, as amended, is an appendix of the National Oil and Hazardous 
Substances Pollution Contingency Plan (NCP). This direct final partial 
deletion is being published by EPA with the concurrence of the State of 
Colorado (State), through the Colorado Department of Public Health and 
Environment (CDPHE) because EPA has determined that all appropriate 
response actions at OU4, OU5 and OU7 under CERCLA, other than 
operation, maintenance, and five-year reviews, have been completed. 
However, this partial deletion does not preclude future actions under 
Superfund.
    This partial deletion pertains to all of OU4, OU5 and OU7. Operable 
Unit 2 (OU2), Malta Gulch Tailing Impoundments and Lower Malta Gulch 
Fluvial Tailing; Operable Unit 8 (OU8), Lower California Gulch; 
Operable Unit 9 (OU9), Residential Populated Areas; and Operable Unit 
10 (OU10), Oregon Gulch, were previously partially deleted from the 
NPL. Operable Unit 1 (OU1), the Yak Tunnel; Operable Unit 3 (OU3), 
D&RGW Slag Piles and Easement; Operable Unit 6 (OU6), Stray Horse 
Gulch; Operable Unit 11 (OU11), Arkansas River Floodplain; and Operable 
Unit 12 (OU12), Site-wide Surface and Groundwater Quality, are not 
being considered for deletion as part of this action and will remain on 
the NPL.

DATES: This direct final partial deletion is effective October 14, 2014 
unless EPA receives adverse comments by September 11, 2014. If adverse 
comments are received, EPA will publish a timely withdrawal of the 
direct final partial deletion in the Federal Register informing the 
public that the partial deletion will not take effect.

ADDRESSES: Submit your comments, identified by Docket ID no. EPA-HQ-
SFUND-1983-0002, by one of the following methods:
     https://www.regulations.gov. Follow on-line instructions 
for submitting comments.
     E-Mail: Linda Kiefer, kiefer.linda@epa.gov.
     Fax: (303) 312-7151.
     Mail: Linda Kiefer, Remedial Project Manager, 
Environmental Protection Agency, Region 8, Mail Code 8EPR-SR, 1595 
Wynkoop Street, Denver, CO 80202-1129.
     Hand Delivery: Environmental Protection Agency, Region 8, 
Mail Code 8EPR-SR, 1595 Wynkoop Street, Denver, CO 80202-1129. Such 
deliveries are only accepted during the Docket's normal hours of 
operation, and special arrangements should be made for deliveries of 
boxed information.
    Instructions: Direct your comments to Docket ID no. EPA-HQ-SFUND-
1983-0002. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
https://www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through https://www.regulations.gov or email. The https://www.regulations.gov Web site 
is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an email comment directly to EPA without 
going through https://www.regulations.gov, your email address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses.
    Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available electronically in 
https://www.regulations.gov; by calling EPA Region 8 at (303) 312-7279 
and leaving a message; and at the Lake County Public Library, 1115 
Harrison Avenue, Leadville, CO 80461, (719) 486-0569, Monday and 
Wednesday from 10:00 a.m.-8:00 p.m., Tuesday and Thursday from 10:00 
a.m.-5:00 p.m., and Friday and Saturday 1:00 p.m.-5:00 p.m.

FOR FURTHER INFORMATION CONTACT: Linda Kiefer, Remedial Project 
Manager, U.S. Environmental Protection Agency, Region 8, Mailcode EPR-
SR, 1595 Wynkoop Street, Denver, CO 80202-1129, (303) 312-6689, email: 
kiefer.linda@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Introduction

[[Page 47008]]

II. NPL Deletion Criteria
III. Partial Deletion Procedures
IV. Basis for Site Partial Deletion
V. Partial Deletion Action

I. Introduction

    EPA Region 8 is publishing this direct final Notice of Partial 
Deletion for all of Operable Unit 4 (OU4), Upper California Gulch; 
Operable Unit 5 (OU5), ASARCO Smelters/Slag/Mill Sites; and Operable 
Unit 7 (OU7), Apache Tailing Impoundment, of the Site, from the NPL. 
The NPL constitutes Appendix B of 40 CFR part 300, of the NCP, which 
EPA promulgated pursuant to section 105 of CERCLA of 1980, as amended. 
EPA maintains the NPL as the list of sites that appear to present a 
significant risk to public health, welfare, or the environment. Sites 
on the NPL may be the subject of remedial actions financed by the 
Hazardous Substance Superfund (Fund). This partial deletion of the Site 
is proposed in accordance with 40 CFR 300.425(e) and is consistent with 
the Notice of Policy Change: Partial Deletion of Sites Listed on the 
NPL. 60 FR 55466 (Nov. 1, 1995). As described in 40 CR 300.425(e)(3) of 
the NCP, a portion of a site deleted from the NPL remains eligible for 
Fund-financed remedial action if future conditions warrant such 
actions.
    Because EPA considers this action to be noncontroversial and 
routine, this action will be effective October 14, 2014 unless EPA 
receives adverse comments by September 11, 2014. Along with this direct 
final Notice of Partial Deletion, EPA is co-publishing a Notice of 
Intent for Partial Deletion in the ``Proposed Rules'' section of the 
Federal Register. If adverse comments are received within the 30-day 
public comment period on this partial deletion action, EPA will publish 
a timely withdrawal of this direct final Notice of Partial Deletion 
before the effective date of the partial deletion and the partial 
deletion will not take effect. EPA will, as appropriate, prepare a 
response to comments and continue with the deletion process on the 
basis of the Notice of Intent for Partial Deletion and the comments 
already received. There will be no additional opportunity to comment.
    Section II of this document explains the criteria for deleting 
sites from the NPL. Section III discusses procedures that EPA is using 
for this action. Section IV discusses OU4, Upper California Gulch; OU5, 
ASARCO Smelters/Slag/Mill Sites; and OU7, Apache Tailing Impoundment, 
and demonstrates how they meet the deletion criteria. Section V 
discusses EPA's action to partially delete the Site parcels from the 
NPL unless adverse comments are received during the public comment 
period.

II. NPL Deletion Criteria

    The NCP establishes the criteria that EPA uses to delete sites from 
the NPL. In accordance with 40 CFR 300.425(e), sites may be deleted 
from the NPL where no further response is appropriate. In making such a 
determination pursuant to 40 CFR 300.425(e), EPA will consider, in 
consultation with the State, whether any of the following criteria have 
been met:

    i. Responsible parties or other persons have implemented all 
appropriate response actions required;
    ii. All appropriate Fund-financed response under CERCLA has been 
implemented, and no further response action by responsible parties 
is appropriate; or
    iii. The remedial investigation has shown that the release poses 
no significant threat to public health or the environment and, 
therefore, the taking of remedial measures is not appropriate.

    Pursuant to CERCLA section 121(c) and the NCP, EPA conducts five-
year reviews to ensure the continued protectiveness of remedial actions 
where hazardous substances, pollutants, or contaminants remain at a 
site above levels that allow for unlimited use and unrestricted 
exposure. EPA conducts such five-year reviews even if a site is deleted 
from the NPL. EPA may initiate further action to ensure continued 
protectiveness at a deleted site if new information becomes available 
that indicates it is appropriate. Whenever there is a significant 
release from a site deleted from the NPL, the deleted site may be 
restored to the NPL without application of the hazard ranking system.

III. Partial Deletion Procedures

    The following procedures apply to the deletion of OU4, OU5 and OU7:
    (1) EPA has consulted with the State prior to developing this 
direct final Notice of Partial Deletion and the Notice of Intent for 
Partial Deletion co-published in the ``Proposed Rules'' section of the 
Federal Register.
    (2) EPA has provided the State 30 working days for review of this 
notice and the parallel Notice of Intent for Partial Deletion prior to 
their publication today, and the State, through the CDPHE, has 
concurred on the partial deletion of OU4, OU5 and OU7 of the Site from 
the NPL.
    (3) Concurrently with the publication of this direct final Notice 
of Partial Deletion, a notice of the availability of the parallel 
Notice of Intent for Partial Deletion is being published in a major 
local newspaper, the Leadville Herald Democrat. The newspaper notice 
announces the 30-day public comment period concerning the Notice of 
Intent for Partial Deletion of OU4, OU5 and OU7 of the Site from the 
NPL.
    (4) The EPA placed copies of documents supporting the partial 
deletion in the deletion docket and made these items available for 
public inspection and copying at the Site information repositories 
identified above.
    (5) If adverse comments are received within the 30-day public 
comment period on this partial deletion action, EPA will publish a 
timely notice of withdrawal of this direct final Notice of Partial 
Deletion before its effective date and will prepare a response to 
comments and continue with the deletion process on the basis of the 
Notice of Intent for Partial Deletion and the comments already 
received.
    Deletion of a portion of a site from the NPL does not itself 
create, alter, or revoke any individual's rights or obligations. 
Deletion of a portion of a site from the NPL does not in any way alter 
EPA's right to take enforcement actions, as appropriate. The NPL is 
designed primarily for informational purposes and to assist EPA 
management. Section 300.425(e)(3) of the NCP states that the deletion 
of a site from the NPL does not preclude eligibility for further 
response actions, should future conditions warrant such actions.

IV. Basis for Site Partial Deletion

    The following information provides EPA's rationale for deleting 
OU4, OU5 and OU7 of the Site from the NPL:

Site Background and History

    The California Gulch Superfund Site, EPA ID No. COD980717938, is 
located in Lake County, Colorado approximately 100 miles southwest of 
Denver. The Site was proposed for inclusion on the NPL on December 30, 
1982, (47 FR 58476), and listed on September 8, 1983, (48 FR 40658). 
The Site is in a highly mineralized area of the Colorado Rocky 
Mountains covering approximately 18 square miles of a watershed that 
drains along California Gulch to the Arkansas River. The Site includes 
the City of Leadville, various parts of the Leadville Historic Mining 
District, Stringtown, and a section of the Arkansas River from the 
confluence of California Gulch to the confluence of Two-Bit Gulch. 
Mining, mineral processing, and smelting activities have occurred at 
the Site for more than 130 years. Mining in the district began in 1860, 
when placer gold was discovered in California Gulch. As the placer 
deposits were

[[Page 47009]]

exhausted, underground mine workings became the principal method for 
removing gold, silver, lead and zinc ore. As these mines were 
developed, waste rock was excavated along with the ore and placed near 
the mine entrances. Ore was crushed and separated into metallic 
concentrates at mills, with mill tailing generally released into 
surrounding streams and after about 1930 slurried into tailing 
impoundments. Many of the mining operations ceased operations around 
1900, although several smelters continued operations into the 1920s 
(Western Zinc) and the 1960s (AV Smelter) and the last active mine, the 
Black Cloud, shut down in 1999.
    All of the mines within the Site boundaries are presently inactive, 
and all of the mills and smelters have been demolished. Mining remains 
that contributed to environmental contamination are (1) mill tailing 
(the fine-grained residue remaining after milling has removed the metal 
concentrates form the ore) in impoundments and fluvial deposits, (2) 
mine waste rock piles (mine development rock and low grade ore removed 
to gain access to an ore body, and often deposited near adits and shaft 
openings), (3) mine water drainage tunnels, (4) draining adits, and (5) 
various smelter wastes including slag piles, flue dust and fallout from 
stack emissions.
    The Site was placed on the NPL due to concerns regarding the impact 
of acidic and metals laden mine drainage on surface waters leading to 
California Gulch and the impact of heavy metals loading into the 
Arkansas River. A Site-wide Phase I Remedial Investigation (Phase I 
RI), which primarily addressed surface water and groundwater 
contamination, was issued in January 1987. As a result of the Phase I 
RI, EPA identified the first operable unit, the Yak Tunnel, to address 
the largest single source of metallic loading. A number of additional 
Site-wide studies followed the Phase I RI.
    EPA agreed, pursuant to a May 2, 1994 Consent Decree (1994 CD), to 
divide the Site into 12 operable units (OUs). With the exception of 
OU12, the OUs pertain to distinct geographical areas corresponding to 
areas of responsibility for the identified responsible parties and/or 
to distinct sources of contamination. The OUs are as follows: OU1, Yak 
Tunnel/Water Treatment Plant; OU2, Malta Gulch Tailing Impoundments and 
Lower Malta Gulch Fluvial Tailing; OU3, D&RGW Slag Piles and Easement; 
OU4, Upper California Gulch; OU5, ASARCO Smelter Sites/Slag/Mill Sites; 
OU6, Starr Ditch/Stray Horse Gulch/Lower Evans Gulch/Penrose Mine Waste 
Pile; OU7, Apache Tailing Impoundments; OU8, Lower California Gulch; 
OU9, Residential Populated Areas; OU10, Oregon Gulch; OU11, Arkansas 
River Valley Floodplain; and OU12, Site-wide Surface and Groundwater. 
To date, OU2, OU8, OU9, and OU10 have been partially deleted from the 
NPL.
    The background and history, the Remedial Investigations and 
Feasibility Studies (RI/FS), Removal and Response Actions, Selected 
Remedies, Cleanup Standards, and Operation and Maintenance activities 
for OU4, OU5 and OU7 are discussed below.

OU4 Background and History

    Upper California Gulch (OU4) is located to the southeast of the 
City of Leadville. A map of OU4 can be found in the docket at https://www.regulations.gov under Docket ID no. EPA-HQ-SFUND-1983-0002. OU4 
covers an area of approximately 2.4 square miles, contains waste rock 
piles and fluvial tailing and is divided into six sub-basins, 
Garibaldi, Whites Gulch, Nugget Gulch, AY Minnie, Iron Hill and South 
Area, which also includes the Fluvial Tailing Site 4 known as Oro City. 
Although 131 waste piles were initially identified in OU4, the number 
of waste rock piles of concern in the OU has been reduced to 20 through 
remedial investigation and analytical screening. The twenty waste rock 
piles in these sub-basins contain a total estimated volume of 431,000 
cubic yards, impacting 28.3 acres. The waste rock piles are primarily 
weathered porphyry with limited to no vegetation and with highly 
oxidized surfaces.
    Fluvial tailing deposition within OU4 is discontinuous and appears 
to have been subdivided into several distinct pockets. In OU4, the 
Fluvial Tailing Site 4 extends for a distance of approximately 1.5 
miles along Upper California Gulch, from slightly upstream of the Yak 
Tunnel portal to the upstream end of the Printer Boy Mine area. Fluvial 
tailing and fluvial tailing mixed with alluvial sediments are located 
in the South Area and Fluvial Tailing Site 4 (Oro City), and are 
estimated at 102,000 cubic yards in volume. The fluvial tailing piles 
are largely un-vegetated, with grasses and lodgepole pine growing on 
approximately a quarter of the tailing surface. A wetland area exists 
along the Upper California Gulch channel within the OU4 boundaries. Oro 
City is considered a cultural and historic resource for the Leadville 
Historic Mining District. The land in OU4 is zoned by Lake County for 
recreational, industrial and mining land uses. EPA is the lead agency 
for OU4 and the CDPHE is the support agency. Under the 1994 CD, 
Resurrection/Newmont Mining (Resurrection/Newmont) assumed 
responsibility for OU4.
    Concurrent with the various investigations and studies, risk 
assessments were conducted. They included the Preliminary Baseline Risk 
Assessment (Preliminary BRA), the Final Baseline Human Health Risk 
Assessments (Final BRA): Part A, Part B, and Part C; the Ecological 
Risk Assessment for Terrestrial Ecosystems (ERA); the Surface Water 
Human Health Risk Assessment; the Groundwater Baseline Human Health 
Risk Assessment and the Baseline Aquatic Ecological Risk Assessment 
(BARA).
    For human health risk issues at OU4, the Preliminary BRA and the 
Final BRA Part C, Evaluation of Worker Scenario and Evaluation of 
Recreational Scenarios, were most pertinent. The Preliminary BRA 
indicated that lead and arsenic are responsible for the majority of 
human health risks at the Site. Therefore, arsenic and lead were used 
as indicator contaminants for risk in the Final BRA. Residential, 
commercial, and industrial uses do not occur in OU4, nor are these uses 
anticipated to occur in the future at OU4. Therefore, commercial 
workers, industrial workers, and residents are not exposed to 
contaminated media in OU4. Recreation is the most likely land use 
scenario for OU4. Therefore, recreational visitors were selected as the 
receptors of concern for OU4. The Final BRA identified soil ingestion 
as the exposure pathway of concern for recreational visitors. Exposure 
to other media and exposure to soil/dust through other pathways (e.g., 
dermal) are considered an insignificant concern for recreational users. 
The OU4 investigations showed that average concentrations of arsenic 
and lead in exposure areas in OU4 where recreational use is considered 
likely were less than the risk-based action levels for the recreational 
land use scenario (lead 16,000 mg/kg and arsenic 1,400 mg/kg) 
identified in the Final BRA, indicating that an unacceptable health 
risk is unlikely to result from recreational exposure to lead or 
arsenic in surface soils in OU4.
    For ecological risks at OU4, the BARA and the ERA were the most 
pertinent. The BARA characterized the impacts of mine waste 
contamination on the aquatic ecosystem of the Site. Results of the BARA 
indicate that mine waste poses potential unacceptable risk to all 
aquatic species. The BARA states that the Girabaldi Mine, the North 
Mike, and the fluvial tailing, as well as other

[[Page 47010]]

sources, such as high metal waste rock piles, contribute to the metals 
entering California Gulch and, ultimately, the Arkansas River. 
Potential risks to the terrestrial ecosystem from mine waste 
contamination were characterized in the ERA. Risks to the blue grouse, 
mountain bluebird, and least chipmunk exceeded EPA acceptable levels 
for exposure to contaminants in mine waste contamination in OU4. 
Potential risks to plants and soil fauna from exposure to mine waste 
contamination were also indicated. Surface water ingestion may also 
result in a potential risk of some effect to terrestrial receptors. 
Action levels were not developed for terrestrial receptors. Thus, these 
releases of contaminants from OU4 presented an unacceptable risk to 
aquatic and terrestrial ecological receptors and response actions were 
necessary at OU4 to control the release of contaminants and acidic 
water into the environment.

OU4 Remedial Investigations and Feasibility Study (RI/FS)

    The State, the EPA and certain Potentially Responsible Parties 
(PRPs) have conducted various studies and investigations to evaluate 
the nature and extent of contamination generally at the Site, and 
specifically within OU4. Remedial Investigations (RIs) began in 1986 
within the Site, including mine waste rock piles, tailing disposal 
areas, surface water and aquatics, groundwater, smelter sites, 
residential/populated area soils, slag piles, and terrestrial studies. 
The Yak Tunnel/California Gulch Remedial Investigation (1986 RI) 
evaluated the human health and environmental impacts due to historic 
mining activities. Waste rock piles were selected for sampling based 
upon their potential to impact surface water systems. Waste rock and 
fluvial tailing material samples (from 0 to 6 inches) were collected at 
14 sites in OU4. Waste rock and/or tailing samples were collected in 
the Iron Hill drainage, at the Garibaldi, Agwalt, Printer Girl, and AY-
Minnie mine sites, and along Fluvial Tailing Site 4.
    In 1986 and 1987, EPA conducted additional RI investigations. The 
Draft Phase II Remedial Investigation Technical Memorandum 1986-1987 
(Phase II RI) evaluated mine-related wastes, surface water and 
groundwater quality, associated with the Printer Girl and the AY-Minnie 
mine sites. The California Gulch Hydrologic Investigation, included 
surface water, groundwater, and sediment sampling; laboratory analysis 
of samples; and an inventory of mine and mineral waste. The primary 
objectives were to characterize the surface and groundwater quality and 
flow patterns, and to identify sources of contaminant loading in 
California Gulch. Conducted in 1991 and 1992, the Final-Surface Water 
Remedial Investigation Report (Surface Water Rl), prepared by ASARCO, 
involved surface water and sediment sampling in the Arkansas River and 
its tributaries, including California Gulch.
    The Final-Hydrogeologic Remedial Investigation Report 
(Hydrogeologic RI), prepared for ASARCO, from the fall of 1991 through 
the winter of 1992, included well monitoring, and groundwater analysis. 
The objectives were to investigate groundwater quality and flow 
directions, evaluate potential impacts to water users and surface water 
receptors, and to characterize background groundwater quality.
    Issued in 1994, the Final-Tailing Disposal Area Remedial 
Investigation Report (Tailing RI) discusses the investigation of the 
five major tailing impoundments and seven fluvial tailing deposits, and 
their potential impacts on surface and groundwater at the California 
Gulch Site for ASARCO in the fall of 1991.
    The 1994 Draft Final-Field Reconnaissance Survey of Mine Waste 
Piles Located Within the Upper California Gulch Drainage identified 131 
individual waste rock piles and ranked these waste rock piles for two 
criteria: (1) Potential physical instability that may expose or spread 
materials, and (2) minerals contained on the surface of the pile.
    In addition to the Site investigations, cultural resource surveys 
were conducted at the Garibaldi, the North Moyer, Agwalt, and the 
Printer Girl mine sites in 1990, 1994, and 1995. Resurrection/Newmont 
conducted additional field investigation activities in 1994 and 1995 to 
evaluate the potential for waste rock piles to generate acid rock 
drainage (ARD) and leach metals; to further define conditions within 
OU4; to supplement existing RI information with additional physical, 
chemical, and geotechnical data; and to provide supplemental 
information for use in an Engineering Evaluation/Cost Analysis (EE/CA) 
and a Focused Feasibility Study (FFS).
    Resurrection/Newmont completed an EE/CA in 1995 (1995 OU4 EE/CA). 
The 1995 OU4 EE/CA was prepared to evaluate and identify a preferred 
non-time critical removal action for the Garibaldi Mine site area 
within OU4. Resurrection/Newmont completed the FFS for OU4 of the 
California Gulch Site in January 1998 (1998 OU4 FFS). The purpose of 
the 1998 OU4 FFS was to identify and evaluate remedial alternatives to 
address potential sources of contaminant loading within the OU4 site 
area. The 1998 OU4 FFS provided a detailed analysis for the following 
waste rock piles and fluvial tailing material: Waste rock near the 
Garibaldi Mine; waste rock in Upper Whites Gulch; waste rock and 
fluvial tailing near the AY-Minnie and Printer Boy mining areas; waste 
rock piles at North Moyer/North Mike; and mine waste rock piles located 
near the Minnie pump shaft.
    Based on the results of the numerous remedial investigations and 
the 1998 OU4 FFS for OU4, the EPA determined, at the time, that actual 
or threatened releases of hazardous substances from waste rock and 
fluvial tailing piles in OU4 may present an imminent and substantial 
endangerment to public health, welfare or the environment if not 
addressed through remedial action. Metals from former mining 
activities, present in waste rock and fluvial tailing piles, may leach 
to surface water or groundwater via ARD. Response actions were 
necessary at OU4 to control the release of contaminants and acidic 
water into the environment. These releases presented a risk to aquatic 
and terrestrial ecological receptors.

OU4 Removal Actions

    In the 1994 CD, Resurrection/Newmont agreed to perform certain 
remediation work in three operable units (OU4, OU8, and OU10). The Work 
Area Management Plan (WAMP), included as Appendix D to the 1994 CD, 
defines the scope of work to be performed by Resurrection/Newmont. The 
1995 OU4 EE/CA included site characterization, (utilizing existing 
remedial investigation data and collected field data) to be used to 
identify removal action objectives and alternatives. The 1995 OU4 EE/CA 
provided information to enable the EPA to select several removal 
actions.
    Pursuant to the August 4, 1995 and July 19, 1996 Action Memorandums 
and the November 18,1996 Amended Action Memorandum, Resurrection/
Newmont conducted Non-Time Critical Removal Actions at the Garibaldi 
sub-basin, the Agwalt Mine in Whites Gulch, and the Upper California 
Gulch surface water diversion. These removal actions successfully 
addressed contamination at the Garibaldi and the Agwalt mine sites. The 
removal actions included construction of portal collection systems and 
concrete-lined channels to intercept and divert surface water run-on 
and portal flow away from two waste rock piles. The Garibaldi removal 
action also included two groundwater interception trenches to divert 
groundwater flow.

[[Page 47011]]

OU4 Selected Remedy

    The EPA issued the Record of Decision (ROD) for OU4 (1998 OU4 ROD) 
on March 31, 1998. The Remedial Action Objectives (RAOs) established in 
the 1998 OU4 ROD include: (1) Control erosion of contaminated materials 
into local water courses, (2) Control leaching and migration of metals 
from contaminated materials into the surface water, and (3) Control 
leaching and migration of metals from contaminated materials into the 
groundwater.
    The selected remedy for OU4 consisted of the following remedial 
components: (1) Within the Garabaldi sub-basin, creation of a diversion 
of surface water and selected removal of waste; (2) within the Whites 
Gulch sub-basin, the excavation, consolidation and removal of waste 
rock at the Printer Girl Waste Rock Pile, and the regrading of 
excavated areas of the Printer Girl Waste Rock Pile and construction of 
diversion ditches to control surface water run-on to the regraded 
areas; (3) within the Nugget Gulch sub-basin: Excavation and 
consolidation of the Rubie, Adirondack, Colorado No. 2 east and North 
Mike Waste Rock Piles onto the Colorado No. 2 Waste Rock Piles; 
regrading and placement of a simple rock or vegetated cover over the 
Colorado No. 2 Waste Rock Pile, terracing, soil amendment and 
revegetation of excavated areas, and construction of diversion ditches 
to control surface water run-on to the terraced and regraded areas; (4) 
within the AY Minnie sub-basin: Construction of diversion ditches to 
reduce surface water run-on onto the AY Minnie Waste Rock Pile, and 
relocation of Lake County Road 2 to allow space for construction of a 
sedimentation pond and provide added protection from stability failures 
of timber cribbing without destroying the mining heritage and cultural 
resources of this mining area; Iron Hill sub-basin: Regrading and 
placement of a simple cover (revegetated soil or rock) over the Mab 
Waste Rock Pile as well as revegetation of surrounding disturbed areas; 
and (5) within Oro City, reconstruction and stabilization of the Upper 
California Gulch stream channel to prepare for a 500-year flood event, 
and regrading and removal, if necessary, of channel spoil material and 
selected fluvial tailing, and construction of eight sediment dams 
within the channel and approximately 1.5 acres of wetlands along the 
channel.
    On March 17, 2004, the EPA issued an Explanation of Significant 
Differences (ESD) deferring remedial activities at Fluvial Tailing Site 
4/Oro City because of the historical significance of the Oro City area 
as an early mining camp. Spring runoff in the Oro City area is 
monitored as part of OU12, Site-wide water quality. Because the 
selected remedy in the 1998 OU4 ROD left wastes in place but did not 
include institutional controls (ICs), a second ESD was signed on July 
29, 2013 to include ICs as part of the OU4 source control remedy for 
the Site.

OU4 Cleanup Standards

    The 1998 OU4 ROD addressed potential source material contributing 
to surface water and groundwater contamination at the Site but did not 
contain numeric cleanup standards. As previously mentioned, the OU12 
remedy addresses site-wide surface water and groundwater contamination 
and includes numeric cleanup standards.

OU4 Response Actions

    The 1998 OU4 ROD identified the need for additional remedial 
actions in Whites Gulch (Printer Girl Waste Pile), Nugget Gulch Waste 
Rock, AY Minnie Waste Rock, Iron Hill Waste Rock, and Fluvial Tailing 
Site 4/Oro City. Resurrection/Newmont commenced these remedial actions 
in June 1998 and completed the work in February 2003. The major 
components of the remedial action included controlling erosion of 
contaminated materials into local watercourses, controlling leaching 
and migration of metals from contaminated materials into the surface 
water, and controlling leaching and migration of metals from 
contaminated materials into the groundwater.

OU4 Operation and Maintenance

    Under the 1994 CD and a 2008 Consent Decree settlement (2008 CD) 
that replaced the 1994 CD, Resurrection/Newmont agreed to operate and 
maintain the OU4 remedy features. Resurrection/Newmont conducts 
inspections in accordance with the OU4, OU8, and OU10, Operations and 
Maintenance (O&M) Plan, California Gulch Superfund Site which can be 
found in Appendix D to the 2008 CD approved on August 29, 2008. 
Resurrection/Newmont findings are documented in the Annual California 
Gulch Superfund Site OU4, OU8 and OU10 Inspection Reports. These 
reports are available by contacting EPA Region 8.
    Environmental covenants for Resurrection/Newmont's properties 
within OU4 were recorded with the Lake County Clerk and Recorder on 
July 31, 2012 and October 10, 2012. The environmental covenants provide 
the following Use Restrictions: (1) No Residential Use, Day Care 
Centers or Schools, Parks or Open Space that are designed or intended 
to provide play or recreation areas for children, (2) Restrictions on 
using untreated groundwater from wells, and (3) Restrictions on uses or 
activities that would disturb/interfere or have the potential to 
disturb/interfere with the protectiveness of the remedy and remedial 
components. On December 22, 2010, Lake County implemented ICs that 
covered all property within OU4 in the form of a local ordinance, a 
resolution amending the Lake County Land Development Code and adopting 
regulations that protect both engineered and non-engineered remedies at 
OU4. A best management practice handout is provided to all applicants 
applying for a building permit within OU4. In addition, any disruption 
of engineered or non-engineered remedies, and/or excavation of more 
than 10 cubic yards of soil off-site within OU4 requires written 
approval from the CDPHE. All of OU4 is zoned Industrial Mining by Lake 
County, which serves to limit future changes of land use without County 
approval and notification to the EPA and the CDPHE of such proposed 
changes.

OU5 Background and History

    OU5 includes five smelter sites (Elgin Smelter, Grant/Union 
Smelter, Western Zinc Smelter, Arkansas Valley South Hillside Slag Pile 
(EGWA) and Arkansas Valley Smelter (AV), and one mill site known as 
Colorado Zinc-Lead Mill (CZL). A map of OU5 can be found in the docket 
at www.regulations.gov under Docket ID no. EPA-HQ-SFUND-1983-0002. One 
smelter and the mill are co-located as the AV/CZL sites, approximately 
1.5 miles southwest of Leadville on the north bank of California Gulch. 
The combined area is approximately 70 acres. The entire AV/CZL sites 
lie above the 500-year floodplain of Lower California Gulch. The AV/CZL 
sites are also adjacent to portions of OU3 that includes the AV Slag 
Pile. The AV, which is part of the Leadville Historic Mining District, 
operated from 1879 until 1961. It was the longest-operating smelter in 
the Leadville area, processing a wide variety of ores and reprocessing 
slag to produce lead, silver and other metals during this time. The CZL 
operated intermittently from 1926 to 1938 using a custom flotation 
process to produce zinc, lead, gold, silver and some copper. Tailing, 
the byproduct of the mill operation was discharged below the mill 
presumably into the CZL Tailing Impoundment which is included as part 
of OU8. The mill closed in 1930 and was reopened in 1935. The mill 
processed ores from

[[Page 47012]]

several local mines and waste dumps between 1935 and 1938 when the 
operations ceased.
    The Elgin Smelter, which operated intermittently from 1879 to 1903, 
is located in north-central Leadville on the south bank of Big Evans 
Gulch near the intersection of U.S. Highway 24 and State Highway 91. 
The Elgin Smelter works were leased and operated by several different 
companies between 1893 and 1902. The Grant/Union Smelter was actually 
two smelters: The Grant Smelter, which operated from 1878 to 1882, and 
the Union Smelter which operated from 1892 to 1900. Both smelters were 
located near the confluence of Georgia Gulch and California Gulch, 
northeast of the Colorado Mountain College campus. The Western Zinc 
Smelter, which operated from 1914 until 1926, is located in the western 
part of Leadville, approximately seventy five feet west of McWethy 
Drive and approximately one hundred feet south of the Lake County 
fairgrounds. The Western Zinc Mining and Reducing Company used the 
facility to extract zinc from ores.
    Also referred to as the Tramway Slag Pile, the Arkansas Valley 
South Hillside Slag Pile is located south of U.S. Highway 24 on the 
hillside across from the AV site. It was perhaps used by the AV or the 
Grant/Union Smelter. The Arkansas Valley South Hillside Slag Pile site 
is estimated to consist of 16,000 cubic yards in two elongated piles of 
slag, extending approximately 2,000 feet parallel to California Gulch 
and U.S. Highway 24. There are no smelter remains or any other waste 
materials except slag at this site.
    Prior to the remedial action, smelter debris, which consisted 
primarily of brick, concrete, metal, tile, wood and glass, as well as 
residual mine waste and smelter materials including slag, coke/
charcoal, limestone, ore, matte, tailing and flue dust, covered OU5. 
After remedial action, the majority of the smelter and mill structures 
at the AV/CZL sites have been demolished, though some buildings and 
foundations remain preserved as cultural heritage properties. The EGWA 
sites are currently vacant.
    Potential media of concern in OU5 include tailing, flue dust, and 
non-residential area soils at the AV/CZL sites and slag, non-
residential soils, and residential area soils at the EGWA sites. 
Results of the Preliminary BRA and the Final BRA indicate that human 
receptors are expected to have minimal exposure to slag. Metals from 
former mining practices including lead, arsenic, cadmium, copper and 
zinc, presented a potential risk to human and ecological receptors. The 
majority of human health risks at the Site, generally, have been 
attributed to lead and arsenic. Therefore, these two contaminants were 
selected as indicator chemicals for remedial response.
    Residential use of OU5 is currently limited to one residence, and 
future residential use is not expected. Otherwise, the AV/CZL and EGWA 
sites are currently vacant. Commercial, industrial, and recreational 
uses are the expected future uses at OU5. Therefore, receptors of 
concern at OU5 are commercial and industrial workers and recreational 
visitors. The Final BRA identified soil ingestion as the exposure 
pathway of concern for recreational visitors; ingestion of soil and 
dust was identified as the exposure pathway of concern for commercial/
industrial workers. Exposure to other media (e.g., tailing, waste 
piles, slag) and exposure to soil/dust through other pathways (e.g., 
dermal) are considered of insignificant concern for workers and 
recreational users.
    The soils at the AV Smelter were determined to contain levels of 
arsenic and lead above risk-based action levels for both the 
commercial/industrial land use scenarios (lead 6,100 mg/kg-7,700 mg/kg 
and arsenic 610 mg/kg-690 mg/kg) and the recreational land use scenario 
(lead 16,000 mg/kg and arsenic 1,400 mg/kg-3,200 mg/kg) identified in 
the Final BRA. The highest levels of contamination were detected in 
samples taken from the bag-house area. The CZL site had lead levels 
above the risk-based action level for commercial/industrial uses. The 
Elgin Smelter and the Grant/Union Smelter sampling had lead and arsenic 
levels above risk-based action levels for both commercial/industrial 
uses and recreational uses. Therefore, the contaminated media in OU5 
posed a significant risk to human health.
    As with OU4 above, the BARA and the ERA were the most pertinent in 
evaluating the risk to ecological receptors in OU5. Releases of 
contaminants from OU5 presented an unacceptable risk to aquatic and 
terrestrial ecological receptors and response actions were necessary at 
OU5 to control the release of contaminants and acidic water into the 
environment.

OU5 Remedial Investigations and Feasibility Study (RI/FS)

    In September 1990, the EPA and ASARCO signed an Administrative 
Order on Consent for the performance of soils sampling and air 
monitoring at the Site. In 1991, the EPA issued a Unilateral 
Administrative Order that required ASARCO to conduct studies and 
complete RIs. In August 1994, ASARCO entered into a CD with the United 
States, State and other PRPs to perform certain remediation work in 
OU5, OU7 and OU9. The WAMP, included as Appendix D to the 1994 CD, 
defines the scope of work to be performed by ASARCO.
    Several investigations have been conducted within the Site that 
have addressed the smelter/slag/mill sites. A Smelter Site 
Reconnaissance began in 1991 as part of the Smelter Remedial 
Investigation (Smelter RI), which was conducted in 1991 and 1992, and 
primarily focused on smelter-impacted soils but, also included sampling 
of discrete locations where smelter bag houses, dust chambers, or 
roasting furnaces may have been located. This study was initiated by 
ASARCO and included the Elgin Smelter, Grant/Union Smelter, Western 
Zinc Smelter sites, and Arkansas Valley Smelter sites.
    A Surface Water RI (Surface Water RI) of the California Gulch Site 
was conducted in 1991 and 1992. The final Surface Water RI report was 
issued in 1996 describing the results of the surface water 
investigation. The study included surface water and sediment sampling 
in the Arkansas River and its tributaries, including California Gulch.
    The 1996 Groundwater RI (Hydrogeologic RI) included installation of 
monitoring wells and piezometers, water level measurements, and 
groundwater sampling and analysis. The objectives of the Hydrogeologic 
RI were to investigate groundwater quality and flow directions, 
evaluate potential impacts to surface water receptors, and characterize 
background qroundwater quality.
    Denver and Rio Grande Western Railroad, another PRP at the Site, 
undertook RIs of seven major lead slag piles including the Elgin 
Smelter and Grant/Union Smelter sites and one zinc slag pile, the 
Western Zinc slag pile. The Zinc Slag RI was performed concurrent with 
the Lead Slag Pile RI. Investigation activities during these two RIs 
focused mainly on the slag material that may have the potential to 
leach metals.
    In 1993, the EPA conducted a Screening Feasibility Study (SFS) to 
initiate the overall CERCLA FS process at the California Gulch Site. 
The purpose of the SFS was to develop general response actions and 
identify an appropriate range of alternatives applicable to the various 
contaminant sources to be considered during feasibility studies for the 
California Gulch Site. Remedial alternatives retained in the SFS for 
tailing, flue dust, and non-residential area soils in OU5 for the AV/
CZL sites were further

[[Page 47013]]

evaluated and screened during an FFS. The 2000 OU5 AV/CZL FFS provided 
a detailed analysis of the five retained alternatives from the SFS as 
applied to tailing, flue dust, and non-residential soils. The 1999 OU5 
EGWA FS provided a detailed analysis of the two retained alternatives 
from the SFS as applied to slag and four alternatives from the SFS for 
non-residential area soils. IC were included in the feasibility studies 
for OU5 to provide future protectiveness.
    The Proposed Plan describing the EPA's preferred alternatives was 
issued on July 27, 2000. The preferred alternative for the AV/CZL sites 
was Alternative 3, Consolidation/Containment (Flue Dust Repository and 
Soil Cover). For the EGWA sites, the preferred alternative was 
Alternative 2, Institutional Controls.

OU5 Selected Remedy

    The EPA issued two RODs for OU5. The ROD for the AV/CZL sites on 
OU5 was issued on September 29, 2000. The ROD for the EGWA sites on OU5 
was issued on October 31, 2000.
    The RAOs established in the two RODs for OU5 include: (1) Control 
airborne transport of tailing particles, flue dust and soil, (2) 
Control erosion of tailing, flue dust and contaminated materials into 
local water courses, (3) Control leaching and migration of metals from 
tailing, flue dust and soil into surface water, (4) Control leaching 
and migration of metals from tailing, flue dust and soil into 
groundwater, (5) Control contamination exposure to humans, animals and 
aquatic life, and (6) Prevent direct exposure of population to elevated 
contaminant levels in surficial soil.
    The remedy selected for the AV/CZL sites consisted of: (1) 
Excavation of flue dust and relocation to a single-lined, fully 
encapsulated repository, (2) Consolidation of tailing and non-
residential soils and placement of an 18-inch vegetated soil cover over 
the consolidated pile, (3) Implementation of ICs such as deed notices 
or deed restrictions to provide notification that a barrier is in place 
and to restrict land uses incompatible with the remedy, and (4) 
Development of an O&M program during remedial design to include 
inspection and maintenance of the cover and surface water controls, as 
well as inspection for evidence of erosion, differential settlement of 
the cover and adequacy of vegetation.
    The remedy selected for the EGWA sites consisted of implementation 
of ICs to warn of potential hazards and to maintain the effectiveness 
of the remedy by limiting access to or use of the property for current 
or potential future land use scenarios.

OU5 Cleanup Standards

    The 2000 OU5 RODs for the EGWA sites and AV/CZL sites did not 
contain numeric cleanup standards, but were meant to address potential 
source material contributing to surface water and groundwater 
contamination. The OU12 remedy addresses site-wide surface water and 
groundwater contamination.

OU5 Response Actions

    Implementation of the 2000 OU5 ROD for the AV/CZL sites began in 
June 2002. Some smelter structures were demolished, flue dust was 
excavated and the contaminated materials were transported to an on-site 
repository. Tailing and contaminated soil were consolidated on site and 
placed under eighteen inches of clean soil cover which was then 
vegetated. Diversion ditches to prevent run-on and ponding on the 
consolidated waste pile were also constructed. Remedial actions were 
initiated by ASARCO, but discontinued when ASARCO filed for bankruptcy. 
The EPA assumed lead responsibility for implementation of the remedy at 
OU5 through a settlement agreement signed between ASARCO and the 
federal government in 2008. The EPA completed AV/CZL OU5 remedial 
action in 2010. Both the OU5 RODs for the EGWA sites and the AV/CZL 
sites included implementation of ICs as part of the remedy. Lake County 
has adopted a local ordinance as an IC for the EGWA sites and AV/CZL 
sites. See the OU5 and OU7 Operations and Maintenance section below for 
information regarding O&M and ICs in OU5.

OU7 Background and History

    OU7, the Apache Tailing Impoundments, consisted of four distinct 
tailing impoundments located on the southern edge of the City of 
Leadville adjacent to U.S. Highway 24. These impoundments are located 
in California Gulch, approximately 1,500 feet downstream from the Yak 
Tunnel Water Treatment Plant surge pond. A map of OU7 can be found in 
the docket at https://www.regulations.gov under Docket ID no. EPA-HQ-
SFUND-1983-0002. Tailing, placed in the Main Impoundment and possibly 
the North Impoundment, was generated by a mill located on the hillside 
northeast of the Apache Tailing Impoundments known alternately as the 
Venir Mill, the California Gulch Mill, and the ASARCO Leadville Milling 
unit. The available historical information indicates that this mill 
operated between 1939 and 1956, producing approximately 630,000 cubic 
yards of tailing in the 11.3-acre Main Impoundment and an estimated 
14,500 cubic yards of tailing in the 1.8-acre North Impoundment.
    Apache Energy and Minerals Company operated the Apache Mill from 
the late 1970s into the 1980s. The Apache Mill reprocessed tailing from 
the Main Impoundment and deposited the remaining materials into Tailing 
Ponds No. 2 and No. 3, which were located west and downstream of the 
Main Impoundment and were about 1.5 and 0.5 acres in size, 
respectively. Tailing Ponds No. 2 and No. 3 were consolidated into the 
Main Impoundment under a removal action in 1997.
    For human health risk issues at OU7, the Preliminary BRA and the 
Final BRA Part C, Evaluation of Worker Scenario and Evaluation of 
Recreational Scenarios, were most pertinent. The Preliminary BRA 
indicated that lead and arsenic are responsible for the majority of 
human health risks at the Site. Therefore, arsenic and lead were used 
as indicator contaminants for risk in the Final BRA. Residential use of 
OU7 does not currently occur, nor is future residential use reasonably 
anticipated. Commercial, industrial, and recreational uses are expected 
at OU7. Therefore, commercial and industrial workers and recreational 
visitors were considered as groups that were potentially at risk. The 
Final BRA identified soil ingestion as the exposure pathway of concern 
for recreational visitors and ingestion of soil and dust was identified 
as the exposure pathway of concern for commercial/industrial workers. 
Exposure to other media (e.g., slag piles) and exposure to soil/dust 
through other pathways (e.g., dermal) are considered an insignificant 
concern for workers and recreational users. The OU7 investigations 
showed that the concentrations of lead and arsenic in the surficial 
tailing were below risk-based action levels for both the commercial/
industrial land use scenarios (lead 6,100 mg/kg-7,700 mg/kg and arsenic 
610 mg/kg-690 mg/kg) and the recreational land use scenario (lead 
16,000 mg/kg and arsenic 1,400 mg/kg-3,200 mg/kg) identified in the 
Final BRA. Therefore, the exposed tailing did not pose a significant 
risk to human health.
    For ecological risks at OU7, the BARA and the ERA were the most 
pertinent. The BARA characterized the impacts of mine waste 
contamination on the aquatic ecosystem of the Site. Results of the BARA 
indicate that mine waste poses potential unacceptable risk to all 
aquatic species. The BARA states that Apache Tailing Impoundments as 
well

[[Page 47014]]

as other sources such as high metal waste rock piles, contribute to the 
metals entering California Gulch and, ultimately, the Arkansas River. 
Potential risks to the terrestrial ecosystem from mine waste 
contamination were characterized in the ERA. Risks to the blue grouse, 
mountain bluebird, and least chipmunk exceeded EPA acceptable levels 
for exposure to contaminants in tailing. Potential risks to plants and 
soil fauna from exposure to tailing were also indicated. Surface water 
ingestion may also result in a potential risk of some effect to 
terrestrial receptors. Action levels were not developed for terrestrial 
receptors. Thus, these releases of contaminants from OU7 presented an 
unacceptable risk to aquatic and terrestrial ecological receptors and 
response actions were necessary at OU7 to control the release of 
contaminants and acidic water into the environment.

OU7 Remedial Investigations and Feasibility Study (RI/FS)

    The State, EPA and certain PRPs conducted various studies and 
investigations to evaluate the nature and extent of contamination 
within the Site generally and OU7 specifically. RIs that specifically 
addressed OU7 included the Tailing RI performed in the fall of 1991, a 
Supplemental RI conducted in 1996 and 1997 to respond to questions and 
issues that arose in response to the Draft Apache Tailing FS, issued in 
January 1996 and additional RI work performed between 1997 to 1999 that 
was reported in the final FFS (2000 FFS). The 2000 FFS assessed the 
general conditions of the Apache Tailing Impoundments area, evaluated 
and summarized the nature and extent of contamination within OU7, and 
evaluated remedial alternatives to address the risks and conditions 
identified at OU7.
    The various RI studies concluded that loading from OU7 to 
groundwater (and not surface water) was the dominant process by which 
contaminants moved from OU7. This groundwater provides some loading to 
surface water downstream from OU7, which drains to California Gulch and 
ultimately to the Arkansas River.

Selected Remedy

    The EPA issued the ROD for OU7 on June 6, 2000. The OU7 remedy was 
selected to eliminate or reduce potential threats to humans and the 
environment through the construction of a soil cover with a 
geosynthetic barrier and revegetation followed by implementation of ICs 
and a long-term monitoring plan.
    The RAOs identified in the OU7 ROD for the Apache Tailing 
Impoundments were: (1) Control airborne transport of tailing particles; 
(2) Control erosion of tailing materials and deposition into local 
water courses; and (3) Control leaching and migration of metals from 
tailing into surface water and groundwater.
    The selected remedy for OU7 included: (1) Surface water controls 
including the channelization of California Gulch through the southern 
portion of the Main Impoundment and diversion ditches to provide 
surface water run-on and runoff control; (2) Application of source 
surface controls to the impounded tailing, consisting of regrading the 
impoundment, placement of a multi-layer composite cover over the 
combined tailing area, and revegetating the covered surface; (3) ICs to 
warn of potential hazards and to maintain the effectiveness of the 
remedy by limiting access to or use of the property (current and future 
use scenarios) including temporary and permanent measures; and (4) A 
long-term monitoring program to assess the quality of surface water and 
groundwater following implementation of the remedy. The O&M Plan 
includes inspection and maintenance of the cover and surface water 
controls, including evidence of erosion, differential settlement of the 
cover, and vegetation monitoring.
    Remedial action included: (1) Installation and maintenance of 
temporary sediment, diversion and storm water control structures in 
accordance with the Storm Water Management Plan and maintenance of such 
controls during construction activities; (2) Provision of dust control, 
as necessary, during all excavating, hauling, and placing operations; 
(3) Excavation of dispersed tailing and soil adjacent to the Main 
Impoundment to allow for the construction of temporary sedimentation 
ponds; (4) Demolition of the existing concrete foundations to the west 
of the Main Impoundment; (5) Relocation of a section of sanitary sewer 
line around the North Impoundment, connection to an existing sewer line 
at the east and west ends including two new sewer lateral connections, 
and abandonment of existing manholes and sewer line; (6) Regrading of 
the tailing impoundments as indicated on the drawings and placement of 
excavated material in fill areas between the Main and North 
Impoundments and on top of the Main Impoundment; (7) Removal and 
replacement of the overhead power line running east and west between 
the Main and North Impoundments; (8) Channelization of California Gulch 
through the southern portion of the Main Impoundment; (9) Installation 
of the multi-layer cover system consisting of a geosynthetic clay 
liner, geocomposite drainage layer, and an 18-inch soil cover over the 
regraded tailing impoundments; (10) Construction of permanent diversion 
ditches, berms and swales with appropriate erosion protection to 
provide surface water run-on and runoff control; (11) Extension or 
abandonment of monitoring wells or piezometers as necessary; (12) 
Revegetation of the tailing impoundments and other disturbed areas with 
specified seed mixture; and (13) Site cleanup and demobilization. 
ASARCO's Construction Complete Report is dated December 12, 2003. The 
long-term monitoring of water quality in OU7 is performed as part of 
the Site-wide Water, OU12 remedy.

OU7 Cleanup Standards

    The 2000 OU7 ROD did not contain numeric cleanup standards but 
intended to address air transport of tailing material, erosion of 
tailing material in local waters, and potential source material 
contributing to surface water and groundwater contamination at the 
Site.

OU7 Response Actions

    Multiple removal actions were conducted at OU7 between 1996 and 
2000, including removal of Tailing Ponds No. 2 and No. 3, consolidation 
of material removed from Tailing Ponds No. 2 and No. 3 on the Main 
Impoundment, and placement of erosion protection along the toe of the 
southwest embankment of the Main Impoundment below the clay-tile 
culverts and wooden box culvert outfalls. The December 1997 Removal 
Action Completion Report describes the construction activities in 
detail.

OU5 and OU7 Operation and Maintenance

    Per the 2008 CD settlement, ASARCO was relieved from the 
responsibility for implementing O&M activities at OU5 and OU7. The 
State is performing the O&M for OU5 and OU7 under an agreement with 
EPA. The State performs annual O&M monitoring, and periodic inspection 
and maintenance of the soil cover and surface water control features of 
OU5 and OU7. The O&M Plan was completed on March 20, 2014. O&M 
monitoring and maintenance occurs annually as directed by the O&M plan.
    Lake County, on December 22, 2010 for OU7 and April 15, 2013 for 
OU5, and the City of Leadville, on May 7, 2013 for OU7, implemented ICs 
in the form of local ordinances, resolutions

[[Page 47015]]

amending the Land Development Codes and adopting regulations that 
protect both engineered and non-engineered remedies at OU5 and OU7. A 
best management practice handout is provided to all applicants applying 
for a building permit within OU5 and OU7. In addition, any disruptions 
of engineered or non-engineered remedies, and/or excavation of more 
than 10 cubic yards of soil off-site within OU5 and OU7 require written 
approval from the CDPHE.

Five-Year Review

    The remedies at the entire Site, including OU4, OU5 and OU7 require 
ongoing five-year reviews in accordance with CERCLA section 121(c) and 
Sec.  300.430(f)(4)(ii) of the NCP. The next five-year review for the 
California Gulch Site is planned for 2017.
    In the 2012 five-year review dated September 27, 2012 for the Site, 
the OU4 remedy was determined to be protective in the short-term. 
However, there were concerns regarding continued long-term 
protectiveness because the requirement of ICs was not documented in a 
decision document, however ICs had already been implemented by the PRP 
and Lake County. An ESD dated July 29, 2013 resolved this concern. 
Environmental covenants for Resurrection/Newmont's properties within 
OU4 were recorded with the Lake County Clerk and Recorder on July 31, 
2012 and October 10, 2012. On December 22, 2010, Lake County 
implemented ICs for all the property in OU4 in the form of a local 
ordinance, a resolution amending the Lake County Land Development Code 
and adopting regulations that protect both engineered and non-
engineered remedies at OU4.
    In the 2012 five-year review for the Site, the OU5 and OU7 remedies 
were determined to be protective in the short-term. However, there were 
concerns regarding continued long-term protectiveness because an O&M 
Plan was not in place. The State developed an O&M Plan for OU5 and OU7, 
which EPA accepted on March 20, 2014. O&M monitoring and maintenance is 
occurring annually under the O&M plan.
    Pursuant to CERCLA section 121(c) and the NCP, EPA will conduct the 
next five-year review by September 27, 2017 to ensure the continued 
protectiveness of remedial actions where hazardous substances, 
pollutants, or contaminants remain at the Site above levels that allow 
for unlimited use and unrestricted exposure.

Community Involvement

    Public participation activities have been satisfied as required in 
CERCLA section 113(k), 42 U.S.C. 9613(k) and CERCLA section 117, 42 
U.S.C. 9617. During the courses of these operable units, comment 
periods were offered for proposed plans, five-year reviews, and other 
public meetings. The documents that the EPA relied on for the partial 
deletion of OU4, OU5, and OU7 from the California Gulch Superfund Site, 
are in the docket and are available to the public in the information 
repositories. A notice of availability of the Notice of Intent for 
Partial Deletion has been published in the Leadville Herald Democrat to 
satisfy public participation procedures required by 40 CFR 300.425 
(e)(4).
    The State, the Lake County Commissioners, the City of Leadville are 
supportive of the partial deletion of OU4, OU5 and OU7.

Determination That the Criteria for Deletion Have Been Met

    EPA has consulted with the State, Lake County Commissioners, and 
the City of Leadville on the proposed partial deletion of OU4, OU5, and 
OU7 of the California Gulch Site from the NPL prior to developing this 
Notice of Partial Deletion. Through the five-year reviews, EPA has also 
determined that the response actions taken are protective of public 
health or the environment and, therefore, taking of additional remedial 
measures is not appropriate.
    The implemented remedies achieve the degree of cleanup or 
protection specified in: For OU4, the 1995 and 1996 Non-Time Critical 
Removal Actions, the 1998 OU4 ROD, 2004 OU4 ESD and 2013 OU4 ESD; for 
OU5, the 2000 OU5 RODs for the EGWA and AV/CZL sites; and for OU7, the 
1996 and 1997 Non-Time Critical Removal Actions and the 2000 OU7 ROD.
    All selected removal and remedial action objectives and associated 
cleanup goals for OU4, OU5 and OU7 are consistent with agency policy 
and guidance. This partial deletion meets the completion requirements 
as specified in OSWER Directive 9320.22, Close Out Procedures for 
National Priority List Sites. All response activities at OU4, OU5, and 
OU7 of the Site are complete and the three operable units pose no 
unacceptable risk to human health or the environment. Therefore, EPA 
and CDPHE have determined that no further response is necessary at OU4, 
OU5, and OU7 of the Site.

V. Partial Deletion Action

    The EPA, with concurrence of the State through the CDPHE has 
determined that all appropriate response actions under CERCLA, other 
than operation, maintenance, monitoring and five-year reviews, have 
been completed. Therefore, EPA is deleting all of OU4, Upper California 
Gulch; OU5, ASARCO Smelters/Slag/Mill Sites; and OU7, Apache Tailing 
Impoundment of the Site.
    Because EPA considers this action to be non-controversial and 
routine, EPA is taking it without prior publication. This action will 
be effective October 14, 2014 unless EPA receives adverse comments by 
September 11, 2014. If adverse comments are received within the 30-day 
public comment period, EPA will publish a timely withdrawal of this 
direct final notice of partial deletion before the effective date of 
the partial deletion and it will not take effect. EPA will prepare a 
response to comments and continue with the deletion process on the 
basis of the notice of intent to partially delete and the comments 
already received. There will be no additional opportunity to comment.

List of Subjects in 40 CFR Part 300

    Environmental protection, Air pollution control, Chemicals, 
Hazardous waste, Hazardous substances, Intergovernmental relations, 
Penalties, Reporting and recordkeeping requirements, Superfund, Water 
pollution control, Water supply.

    Dated: July 31, 2014.
Shaun L. McGrath,
Regional Administrator, Region 8.
[FR Doc. 2014-18955 Filed 8-11-14; 8:45 am]
BILLING CODE 6560-50-P