01-3614. National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List

AGENCY:

Environmental Protection Agency (EPA)

ACTION:

Partial direct final deletion of the California Gulch Superfund Site from the National Priorities List (NPL).

SUMMARY:

The Environmental Protection Agency (EPA) Region 8 announces its intent to delete Operable Unit 10 (OU 10) of the California Gulch Superfund Site (Site) from the National Priorities List (NPL) and requests public comment on this action. The NPL constitutes Appendix B of 40 CFR Part 300, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), which EPA promulgated pursuant to Section 105 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended. This partial deletion of the California Gulch Site is proposed in accordance with 40 CFR 300.425(e) and the Notice of Policy Change: Partial Deletion of Sites Listed on the National Priorities List, 60 FR 55466 (Nov. 1, 1995).

OU 10 includes the Oregon Gulch Tailing Impoundment. EPA issued a Record of Decision (ROD) for OU 10 on August 7, 1997. The Remedial Action was completed on September 26, 1999 and was approved by EPA on September 30, 1999. The EPA bases its proposal to delete OU 10 on the determination by EPA and the State of Colorado, through the Colorado Department of Public Health and Environment (CDPHE), that all appropriate response actions under CERCLA have been implemented at OU 10. The California Gulch Superfund Site was listed on the NPL on September 8, 1983.

The Site has been divided into 12, Operable Units (OUs). This partial deletion pertains only to OU 10 of the Site. Response activities will continue at the remaining OUs.

DATES:

This “direct final” action will be effective April 16, 2001 unless EPA receives significant adverse or critical comments by March 19, 2001. If adverse comments are received, EPA will publish a timely withdrawal of the direct final rule in the Federal Register informing the public that the rule will not take effect.

ADDRESSES:

Comments may be mailed to Rebecca Thomas, Remedial Project Manager, Environmental Protection Agency, Region 8, Mail Code 8EPR-SR, 999 18th Street, Suite 300, Denver, CO 80202. Telephone: [phone].

Information Repositories:

Comprehensive information on the California Gulch Site is available through the EPA, Region 8 public docket, which is located at the EPA, Region 8, Superfund Records Center and is available for viewing from 8:00 AM to 4:30 PM, Monday through Friday, excluding holidays. Requests for documents should be directed to the EPA, Region 8, Superfund Records Center. The address for the Region 8 Superfund Records Center is: U.S. Environmental Protection Agency, Region 8, Superfund Record Center, 999 18th Street, 5th Floor, Denver, CO 80202, Telephone [phone].

FOR FURTHER INFORMATION CONTACT:

Rebecca Thomas, Remedial Project Manager, Environmental Protection Agency, Region 8, Mail Code 8EPR-SR, 999 18th Street, Suite 300, Denver, CO 80202. Telephone: [phone].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Introduction

II. NPL Deletion Criteria

III. Deletion Procedures

IV. Basis for Intended Partial Site Deletion

Appendix A—Deletion Docket

Appendix B—Site Coordinates

I. Introduction

The Environmental Protection Agency (EPA), Region VIII announces its intent to delete a portion of the California Gulch Superfund Site (Site) from the National Priorities List (NPL) (40 CFR Part 300 Appendix B) and requests comments on this proposal. The Site is located in Lake County, Colorado. This proposal for partial deletion pertains to Operable Unit 10 (OU10) of the Site, which consists of the Oregon Gulch Tailing Impoundment and Lower Oregon Gulch.

The Site is divided into 12 Operable Units (OUs) pursuant to a 1994 Consent Decree. The 12 OUs comprising the California Gulch Site are as follows:

OU 1 Yak Tunnel/Water Treatment Plant

OU 2 Malta Gulch Tailing Impoundments and Lower Malta Gulch Fluvial Tailing

OU 3 D&RG Slag piles and Railroad Yard/Easement

OU 4 Upper California Gulch

OU 5 Asarco Smelter sites/Slag/Mill sites

OU 6 Starr Ditch/Stray Horse Gulch/Lower Evans Gulch/Penrose Mine Waste Pile

OU 7 Apache Tailing Impoundments

OU 8 Lower California Gulch

OU 9 Residential and Commercial Populated Areas

OU 10 Oregon Gulch

OU 11 Arkansas River Valley Floodplain

OU 12 Site-wide Surface and Ground Water

OUs 2 through 11 were designated in order to facilitate source remediation of specific geographic areas. OUs 2 through 11 pertain to distinct geographical areas and correspond with areas of responsibility for the identified responsible parties. The EPA has taken responsibility for areas where either no responsible party could be identified, the United States was a responsible party, or cash-out settlements had been reached with the responsible parties. OU 12, which covers the entire Site was designated to address Site-wide Surface and Groundwater. OU12 will be addressed after completion of source remediation in OUs 2 through 11. EPA proposes to delete the areas addressed by OU 10 because all appropriate CERCLA response actions have been completed in the areas within OU 10 as described in Section IV. Response activities are not complete at the other OUs at the Site. Those OUs will remain on the NPL and are not the subject of this partial deletion.

The NPL is a list maintained by EPA of sites that EPA has determined 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). Pursuant to 40 CFR 300.425(e) of the NCP, any site or portion of a site deleted from the NPL remains eligible for Fund-financed remedial actions if conditions at the site warrant such action.

EPA will accept any dissenting comments on this partial deletion for thirty days following publication of this notice in the Federal Register.

II. NPL Deletion Criteria

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

Section 300.425(e)(1)(i). Responsible parties or other persons have implemented all appropriate response actions required; or Section 300.425(e)(1)(ii). All appropriate Fund-financed response under CERCLA has been implemented, and no further response action by responsible parties is appropriate; or

Section 300.425(e)(1)(iii). The remedial investigation has shown that the release poses no significant threat to public health or the environment and, therefore, taking of remedial measures is not appropriate.

Section 300.425(e)(3) of the NCP provides that Fund-financed actions may be taken at sites that have been deleted from the NPL. Therefore, deletion of an operable unit at a site from the NPL does not preclude eligibility for subsequent Fund-financed actions at the operable unit deleted if future site conditions warrant such actions. A partial deletion of a site from the NPL also does not affect or impede EPA's ability to conduct CERCLA response activities at operable units not deleted and remaining on the NPL. In addition, deletion of a portion of a site from the NPL does not affect the liability of responsible parties or impede agency efforts to recover costs associated with response efforts.

III. Deletion Procedures

Deletion or partial deletion of a site from the NPL does not itself create, alter, or revoke any individual's rights or obligations. The NPL is designed primarily for informational purposes and to assist EPA management.

The following procedures were used for the intended partial deletion of this site:

(1) EPA, Region VIII has recommended the partial deletion of the California Gulch Site and has prepared the relevant documents.

(2) The State of Colorado through the Colorado Department of Public Health and Environment (CDPHE) has concurred with EPA's recommendation for a partial deletion.

(3) Concurrent with this Notice of Intent to pursue a partial deletion, a notice has been published in local newspapers and has been distributed to appropriate Federal, State and local officials, and other interested parties. These notices announce a thirty (30) day public comment period on the deletion package, which commences on the date of publication of this notice in the Federal Register and a newspaper of record.

(4) EPA, Region VIII has made all relevant documents available in the Regional Office, Superfund Record Center.

EPA is requesting only dissenting comments on the Direct Final Action to Delete. For deletion of the release from the Site, EPA's Regional Office will accept and evaluate public comments on EPA's Final Notice before making a final decision to delete. If necessary, the Agency will prepare a Responsiveness Summary responding to each significant comment submitted during the public comment period. Deletion of the Site from the NPL does not itself create, alter, or revoke any individual's rights or obligations. The NPL is designed primarily for informational purposes and to assist Agency management. As mentioned in Section II of this document, § 300.425 (e)(3) of the NCP states that the deletion of a release from a site from the NPL does not preclude eligibility for future response actions.

IV. Basis for Intended Partial Site Deletion

The following provides EPA's rationale for proposing deletion of OU 10 from the NPL and EPA's findings that the criteria in 40 CFR 300.425(e) are satisfied.

Background

The California Gulch Superfund Site is located in Lake County, Colorado approximately 100 miles southwest of Denver. The California Gulch Superfund Site was listed on the National Priorities List on September 8, 1983, 48 Fed. Reg. 40,658 (1983). The Site is in a highly mineralized area of the Colorado Rocky Mountains covering 16 1/2 square miles of a watershed that drains along California Gulch to the Arkansas River. 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 exhausted, underground workings became the principle 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 slurried into tailing impoundments. The Site was placed on the NPL because of concerns about the impact of mine drainage on surface waters in California Gulch and the impact of heavy metals loading in the Arkansas River.

The Site includes the City of Leadville, various parts of the Leadville Historic Mining District, and a section of the Arkansas River from the confluence of California Gulch to the confluence of Lake Fork Creek.

A site-wide Phase I Remedial Investigation (Phase I RI), which primarily addressed surface and groundwater contamination, was issued in January 1987. As a result of the Phase I RI, EPA developed the first operable unit at the Site, the Yak Tunnel. This first operable unit was designed to address the largest single source of metallic loading.

The Phase I RI was followed by a number of additional site-wide studies, including the Tailing Disposal Area Remedial Investigation Report, Baseline Human Health Risk Assessment Part A, Part B, and Part C, Ecological Risk Assessment for Terrestrial Ecosystems, Baseline Aquatic Ecological Risk Assessment, Groundwater RI, Surface Water RI, Waste Rock RI, and Site-wide Screening Feasibility Study. In addition, OU 10 specific studies were also conducted, including the Final Engineering Evaluation/Cost Analysis for Stream Sediments within Oregon Gulch OU 10, and the Final Focused Feasibility Study for Oregon Gulch.

In order to expedite the clean-up of the Site, EPA agreed, pursuant to the 1994 Consent Decree, to divide the Site into eleven additional Operable Units. With the exception of OU 12, the operable units pertain to distinct geographical areas corresponding to areas of responsibility for the identified responsible parties and/or to distinct sources of contamination. EPA has taken responsibility for operable units where either no responsible party could be identified, the United States was a responsible party, or cash-out settlements had been reached with the responsible parties. Under the 1994 Consent Decree, OUs 2 through 11 were designated to deal with areas where the appropriate responsible party or the United States would conduct source remediation. The Consent Decree recognized that additional source remediation or other appropriate response actions related to surface or ground water could occur as part of OU 12 anywhere within the 16.5 square mile of the Site. The OUs are as follows:

1. Yak Tunnel/Water Treatment Plant

2. Malta Gulch Tailing Impoundments and Lower Malta Gulch Fluvial Tailing

3. D&RG Slag piles and Railroad Yard/Easement

4. Upper California Gulch

5. Asarco Smelter sites/Slag/Mill sites

6. Starr Ditch/Stray Horse Gulch/Lower Evans Gulch/Penrose Mine Waste Pile

7. Apache Tailing Impoundments

8. Lower California Gulch

9. Residential and Commercial Populated Areas

10. Oregon Gulch

11. Arkansas River Valley Floodplain

12. Site-wide Surface and Ground Water

Operable Unit 10 of the California Gulch Site is defined as the 500-year flood plain of Oregon Gulch from its headwaters to its confluence with California Gulch. Sources of metal loading within OU 10 include the Oregon Gulch Tailing Impoundment and miscellaneous tailing and stream sediment contained within the 500-year flood plain of lower Oregon Gulch. Lower Oregon Gulch is defined as the portion of the gulch downstream of the tailing impoundment. The general location of OU 10 is shown on the maps appearing as Exhibits 1 & 2. Pursuant to the 1994 Consent Decree, Resurrection Mining Company is responsible for conducting all appropriate response actions at OU 10.

OU 10 Response Actions

OU 10 (Oregon Gulch) is located approximately one-half mile south of the City of Leadville, Colorado. The Oregon Gulch Tailing Impoundment and the flood plain of Oregon Gulch, i.e., Lower Oregon Gulch, comprise approximately 14.2 and 1.6 acres, respectively. Oregon Gulch is a small V-shaped valley with surface water flowing in a northwesterly direction. The gulch extends approximately one mile from its headwaters to the confluence with California Gulch. The tailing impoundment is located approximately 1/2 mile upstream of the confluence of Oregon and California gulches.

The Oregon Gulch Tailing Impoundment received tailing from the Resurrection-Asarco mill in California Gulch from approximately 1942 through 1957. The impoundment contains a volume of material estimated at 485,000 cubic yards.

The studies have shown that due to erosion of tailing, surface water runoff from the impoundment and a seep at the toe of the impoundment, the stream sediment within lower Oregon Gulch has been contaminated with inorganic metals. Resurrection completed the Final Engineering Evaluation/Cost Analysis (EE/CA) for Stream Sediments within Oregon Gulch OU 10, California Gulch Superfund Site, Leadville, Colorado in June 1995. The EE/CA was prepared to evaluate and identify a removal action for miscellaneous tailings and stream sediment contained within the 500-year floodplain of Oregon Gulch. Pursuant to the August 1995 Action memorandum, Resurrection conducted a Non-Time Critical Removal Action in 1995 and 1996. This removal action was directed at addressing eroded tailing and contaminated sediment in Lower Oregon Gulch and involved:

(1) Construction of haul roads.

(2) Installation of erosion control measures (straw bails, gabion check dams, and silt fencing).

(3) Construction of a sediment control pond approximately 500 feet downstream of the toe of the tailing impoundment.

(4) Excavation of sediment from the Oregon Gulch channel to a depth of 1.5 to 2.5 feet (approximately 4923 cubic yards) and placement of the sediment on top of the tailing impoundment.

(5) Construction of a riprap-lined triangular channel, 1-foot deep with 3H:1V side slopes capable of conveying the 10-year flood.

(6) Construction of a riprap-lined trapezoidal channel with a 6-foot bottom width and 3H:1V side slopes capable of conveying the 500-year flood within the Cultural Resource Area.

(7) Reconstruction of the flood plain by placing, grading and seeding amended soil from the borrow area and regrading and constructing temporary storm water diversion ditches as needed.

(8) Material from a borrow area was used to build sediment control structures and to reconstruct the floodplain in lower Oregon Gulch. The borrow material was analyzed to ensure that it would be satisfactory for such use. Analytical results for samples collected from the borrow area are available in the aforementioned EE/CA.

(9) Removal of eroded tailing and contaminated sediment was based on visual inspection.

The removal action successfully addressed eroded tailing and contaminated sediment in lower Oregon Gulch.

Resurrection completed the Final Focused Feasibility Study for Oregon Gulch, Operable Unit 10, California Gulch Site, June 1997. The purpose of the Focused Feasibility Study (FFS) was to identify and evaluate remedial alternatives for the Oregon Gulch Tailing Impoundment and miscellaneous tailing and contaminated sediment within the 500-year floodplain of Oregon Gulch. The FFS provided a detailed analysis of five remediation alternatives. EPA then issued the Record of Decision, Oregon Gulch, Operable Unit 10, California Gulch Superfund Site, Leadville, Colorado on August 7, 1997.

Resurrection commenced the remedial action in 1998 and completed the work in 1999. The major components of the remedial action included:

• Reconstruction of Lower California Gulch and Floodplain.
• Installation of erosion control structures using straw bales and silt fencing and, after work was complete, removal of all straw bales and silt fencing that were no longer needed.
• Fluvial tailing excavated from Operable Unit 8 of the California Gulch Site, (Lower California Gulch) consisted of a mix of stream sediment, including cobbles, gravel and fine-grained fluvial tailing. Approximately 7,100 cubic yards of this material was transported from OU8 to the Oregon Gulch Tailing Impoundment. This work was performed from July 27, 1998 to October 7, 1998. Additional information regarding the OU 8 work is available in the Removal Action Work Plan for Selected Fluvial Tailing and Stream Sediment in Operable Unit 8, April 1998. (This work was done pursuant to Operable Unit 8 and is included here solely because the Oregon Gulch Tailing Impoundment served as the repository for the OU8 tailing.)
• Installation of an upgradient groundwater interceptor trench.
• Regrading the surface of the Oregon Gulch tailing impoundment and construction and revegetation of the tailing impoundment cover. Material from the borrow area previously described in the Removal Action, was also used in the Remedial Action.
• Installation of a seep collection system.
• Installation of a seep management system consisting of a seep storage tank, pump, float control unit, electric hook-up, a drainage basin and pipe, and a discharge line to the YAK Tunnel Water Treatment Plant. A heated and insulated housing unit was constructed around the system.
• The goal of this response action was to prevent infiltration of water into the tailing, prevent erosion of the tailing, and to treat the impoundment seep until it was gone.

A final inspection was completed on September 20, 1999. The remedy was operating as intended. Operation and maintenance of the Oregon Gulch Tailing Impoundment and related systems is required to assure that the remedy remains effective. This includes inspection of the tailing impoundment cap and the seep collection and pumping systems. The Operation and Maintenance Plan for the Seep Collection System, the Seep Management System, the Tailing Impoundment Cover and Diversion Structures, are described in detail in Section 4.0 of the Final Remedial Design for Oregon Gulch, Operable Unit 10, California Gulch Superfund Site, Leadville, Colorado, June 1998. The O&M program for this is being implemented by Resurrection. Resurrection commenced this program in September 1999.

Cultural Resources

Foothill Engineering Consultants, Inc. (FEC) performed a cultural resource inventory that identified a historic trash dump in lower Oregon Gulch. This dump site, identified as 5LK844, begins near the intersection of the gulch and County Road 6 and extends approximately 500 feet upstream. FEC recommended Site 5LK844 as potentially eligible for nomination to the National Register of Historic Places. The Removal Action and the Remedial Action were designed and constructed to avoid any adverse impact to Site 5LK844.

Community Involvement

In May 1995, the public was notified in the local newspaper that the draft Engineering Evaluation/Cost Analysis (EE/CA) for the Stream Sediments within Oregon Gulch, California Gulch Superfund Site, Leadville, Colorado, dated February 1995 was available for public review and comment. EPA held a public meeting in Leadville on June 15, 1995. Comments were submitted and they are attached to the final EE/CA report in a separate Responsiveness Summary. An Action Memorandum was issued on August 4, 1995.

A notice of availability of the Proposed Plan for OU 10 and supporting documents was published in the Leadville Herald Democrat on March 13, 1997. The public comment period was held from March 19, 1997 to April 18, 1997. A Public meeting was held on March 19, 1997. No comments were received during the public comment period. On August 7, 1997, EPA issued a ROD for OU 10 presenting EPA's selected remedy for OU 10 the California Gulch Superfund Site.

Current Status:

Based on the successful completion of the Removal Action and the Remedial Action, there are no further response actions planned or scheduled for this OU.

Because this decision results in hazardous substances remaining on site, above health based levels, five-year reviews of the previous response actions will be required pursuant to the NCP. These reviews will be conducted in conjunction with site-wide five-year reviews. The next five-year review at the California Gulch Site is scheduled to be initiated in October 2000 for completion by March 30, 2001. In addition to the five-year reviews, the Consent Decree establishes an institutional control by requiring deed notices that refer back to the Consent Decree and its associated requirements. Such a deed notice would apply to properties owned by Resurrection, or the Res-Asarco joint venture, within OU 10.

EPA, with concurrence from the State of Colorado, has determined that all appropriate CERCLA Response actions have been completed at OU 10 and protection of human health and the environment has been achieved. Therefore EPA is deleting OU 10 of the California Gulch Superfund Site from the NPL. This action will be effective April 16, 2001. However, if EPA receives dissenting comments by March 19, 2001, EPA will publish a document that withdraws this action.

While EPA does not believe that any future response actions within Operable Unit 10 will be needed, if future conditions warrant such action, the deleted area of Oregon Gulch will remain eligible for future response actions. Furthermore, this partial deletion does not alter the status of the Site-wide Surface and Ground Water operable unit of the California Gulch Superfund Site which is not proposed for deletion and remains on the NPL.

List of Subjects in 40 CFR Part 300

• Environmental protection, air pollution control
• Chemicals
• Hazardous substances
• Hazardous waste
• Intergovernmental relations
• Penalties
• Reporting and record keeping requirements
• Superfund
• Water pollution control
• Water supply

Dated: December 19, 2000.

Jack W. McGraw,

Acting Regional Administrator, US EPA Region 8.

Part 300, title 40 of chapter 1 of the Code of Federal Regulations is amended as follows:

PART 300—[AMENDED]

1. The authority citation for part 300 continues to read as follows:

Authority: 33 U.S.C 1321(c)(2); 42 U.S.C. 9601-9657; E.O. 12777, 56 FR 54757, 3 CFR, 1991 Comp.; p. 351; E.O. 12580, 52 FR 2923, 3 CFR, 1987 Comp.; p. 193.

Appendix B—[Amended]

2. Table 1 of Appendix B to part 300 is amended by revising the entry under Colorado for “California Gulch” to read as follows:

Table 1.—General Superfund Section

State	Site name	City/County	Notes (a)
*         *         *         *         *         *         *
CO	California Gulch	Lake County	P
*         *         *         *         *         *         *