California Gulch Five-Year Report

Page i of v 

### Five-Year Review Report

Table of Contents

Executive Summary.................................................................................................................. ES-1 1.0 Introduction............................................................................................................... .......... 1 2.0 Site Chronology ............................................................................................................ ...... 2 3.0 Background................................................................................................................. ........ 4 4.0 Administrative Components a nd Community Involvement ............................................... 9 5.0 Operable Units ............................................................................................................. ..... 11 6.0 Operable Unit 1-Yak Tunnel/Water Treatment Plant....................................................... 12 6.1 Description............................................................................................................ 12 6.2 Response Actions.................................................................................................. 13 6.3 Progress Since the Last Five Year-Review........................................................... 13 6.4 Five-Year Review Process.................................................................................... 14 6.5 Technical Assessment........................................................................................... 15 6.6 Issues..................................................................................................................... 16 6.7 Recommendations and Follow-Up Actions.......................................................... 17 6.8 Protectiveness Statement ...................................................................................... 17 7.0 Operable Unit 2 - Malta Tailing Impoundme nt, Malta Gulch Tailing Impoundment and Lower Malta Gulch Fluvial Tailing .................................................................................. 18 7.1 Description............................................................................................................ 18 7.2 Response Actions.................................................................................................. 20 7.3 Progress Since the Last Five Year Review........................................................... 21 7.4 Five-Year Review Process.................................................................................... 21 7.5 Technical Assessment........................................................................................... 22 7.6 Issues.................................................................................................................... 23 7.7 Recommendations and Follow-Up Actions.......................................................... 24 7.8 Protectiveness Statement ...................................................................................... 24 8.0 Operable Unit 3 - Denver & Rio Grande Railroad (D&RG) Slag Piles/Railroad Easement/Railroad Yard ................................................................................................... 25 8.1 Description............................................................................................................ 25 8.2 Response Actions.................................................................................................. 27 8.3 Progress Since the Last Five Year Review........................................................... 28 8.4 Five-Year Review Process.................................................................................... 29 8.5 Technical Assessment........................................................................................... 29 8.6 Issues.................................................................................................................... 30 8.7 Recommendations and Follow-Up Actions.......................................................... 30 8.8 Protectiveness Statement ...................................................................................... 31 9.0 Operable Unit 4 - Upper California Gulch ...................................................................... 32 9.1 Description............................................................................................................ 32 9.2 Response Actions.................................................................................................. 33 9.3 Progress Since the Last Five Year Review........................................................... 36 9.4 Five-Year Review Process.................................................................................... 36 9.5 Technical Assessment........................................................................................... 36 9.6 Issues..................................................................................................................... 37California Gulch Five-Year Report

Page ii of v 9.7 Recommendations and Follow-Up Actions.......................................................... 38 9.8 Protectiveness Statement ...................................................................................... 38 10.0 Operable Unit 5 - Asarco Smelters/ Colorado Zinc-Lead Mill Site ................................. 39 10.1 Description............................................................................................................ 39 10.2 Response Actions.................................................................................................. 41 11.0 Operable Unit 6 - Starr Ditch/Penrose Dump/Stray Horse Gulch/Evans Gulch ............. 43 11.1 Description............................................................................................................ 43 11.2 Response Actions.................................................................................................. 45 11.3 Progress Since the Last Five Year Review........................................................... 48 11.4 Five-Year Review Process.................................................................................... 48 11.5 Technical Assessment........................................................................................... 49 11.6 Issues.................................................................................................................... . 50 11.7 Recommendations and Follow-Up Actions.......................................................... 50 11.8 Protectiveness Statement ...................................................................................... 51 12.0 Operable Unit 7 - Apache Tailing Impoundments............................................................ 52 12.1 Description............................................................................................................ 52 12.2 Response Actions.................................................................................................. 54 12.3 Progress Since the Last Five Year-Review........................................................... 56 12.4 Five-Year Review Process.................................................................................... 56 12.5 Technical Assessment........................................................................................... 56 12.6 Issues.................................................................................................................... . 57 12.7 Recommendations and Follow-Up Actions.......................................................... 58 12.8 Protectiveness Statement ...................................................................................... 58 13.0 Operable Unit 8 - Lower California Gulch...................................................................... 59 13.1 Description............................................................................................................ 59 13.2 Response Actions.................................................................................................. 61 13.3 Progress Since the Last Five Year Review........................................................... 64 13.4 Five-Year Review Process.................................................................................... 64 13.5 Technical Assessment........................................................................................... 65 13.6 Issues.................................................................................................................... . 66 13.7 Recommendations and Follow-Up Actions.......................................................... 66 13.8 Protectiveness Statement ...................................................................................... 67 14.0 Operable Unit 9 - Populated Residential Areas ................................................................ 68 14.1 Description............................................................................................................ 68 14.2 Response Actions.................................................................................................. 70 14.3 Progress Since the Last Five Year-Review........................................................... 72 14.4 Five-Year Review Process.................................................................................... 72 14.5 Technical Assessment........................................................................................... 73 14.6 Issues.................................................................................................................... . 74 14.7 Recommendations and Follow-Up Actions.......................................................... 75 14.8 Protectiveness Statement ...................................................................................... 75 15.0 Operable Unit 10 - Oregon Gulch..................................................................................... 76 15.1 Description............................................................................................................ 76 15.2 Response Actions.................................................................................................. 77 15.3 Progress Since the Last Five Year Review........................................................... 80 15.4 Five-Year Review Process.................................................................................... 80 15.5 Technical Assessment........................................................................................... 81 15.6 Issues.................................................................................................................... . 82California Gulch Five-Year Report

Page iii of v 15.7 Recommendations and Follow-Up Actions.......................................................... 82 15.8 Protectiveness Statement ...................................................................................... 83 16.0 Operable Unit 11- Arkansas River Valley Floodplain...................................................... 84 16.1 Description............................................................................................................ 84 16.2 Removal Actions................................................................................................... 85 16.3 Progress Since the Last Five Year-Review........................................................... 87 17.0 Operable Unit 12.......................................................................................................... ..... 88 18.0 Next Review............................................................................................................... ....... 89

Tables

Table 2-1: Chronology of Activiti es at California Gulch Site....................................................... 2 Table 3-1: Land Use-Base d Remediation Goals............................................................................ 7 Table 6-1: Chronology of Site Events for OU1 Yak Tunnel and Water Treatment Plant.......... 12 Table 6-2: OU1 Issues Identified.............................................................................................. ... 16 Table 6-3: OU1 Recommendati ons for Follow-Up Actions........................................................ 17 Table 7-1: Types of Contamin ation in Each Media for OU2 ...................................................... 19 Table 7-2: Chronology of Site Events for OU2........................................................................... 19 Table 7-3: Removal Actions for OU2.......................................................................................... 20 Table 7-4: OU2 Issues Identified.............................................................................................. ... 23 Table 7-5: OU2 Recommendati ons for Follow-Up Actions........................................................ 24 Table 8-1: Types of Contamin ation in Each Media for OU3 ...................................................... 26 Table 8-2: Chronology of Site Events for OU3........................................................................... 26 Table 8-3: OU 3 Issues Identified............................................................................................. ... 30 Table 8-4: OU3 Recommendati ons for Follow-Up Actions........................................................ 30 Table 9-1: Chronology of Site Events for OU4........................................................................... 33 Table 9-2: Remedial and Removal Activities at OU4 ................................................................. 34 Table 9-3: OU4 Issues Identified.............................................................................................. ... 37 Table 9-4: OU4 Recommendati ons for Follow-Up Actions........................................................ 38 Table 10-1: Types of Contam ination in Each Media................................................................... 39 Table 10-2: Chronology of Site Events for OU5......................................................................... 40 Table 10-3: Remedial Actions for OU5....................................................................................... 41 Table 11-1: Types of Contam ination in Each Media................................................................... 44 Table 11-2: Chronology of Site Events for OU6......................................................................... 44 Table 11-3: Removal Actions for OU6........................................................................................ 45 Table 11-4: OU6 Issues Identified............................................................................................. .. 50 Table 11-5: OU6 Recommendati ons for Follow-Up Actions...................................................... 50 Table 12-1: Types of Contam ination in Each Media................................................................... 52 Table 12-2: Chronology of Site Events for OU7......................................................................... 53 Table 12-3: Removal and Remedial Actions for Apache Tailing Impoundments....................... 54 Table 12-4: OU7 Issues Identified............................................................................................. .. 57 Table 12-5: OU7 Recommendati ons for Follow-Up Actions...................................................... 58 Table 13-1: Types of Contamination in Sites Within OU8 ......................................................... 60 Table 13-2: Chronology of Site Events for OU8......................................................................... 61 Table 13-3: Removal/Remedial Actions for OU8 ....................................................................... 62 Table 13-4: OU8 Issues Identified............................................................................................. .. 66 Table 13-5: OU8 Recommendati ons for Follow-Up Actions...................................................... 66California Gulch Five-Year Report

Page iv of v Table 14-1: Chronology of Site Events for OU9......................................................................... 68 Table 14-2: Removal Actions for OU9........................................................................................ 70 Table 14-3: Trigger Levels for Lead........................................................................................... . 71 Table 14-4: OU9 Issues Identified............................................................................................. .. 74 Table 14-5: OU9 Recommendati ons for Follow-Up Actions...................................................... 75 Table 15-1: Types of Contam ination in Each Media................................................................... 76 Table 15-2: Chronology of Site Events for OU10....................................................................... 77 Table 15-3: Removal and Re medial Actions for OU10............................................................... 78 Table 15-4: OU10 Issues Identified............................................................................................ . 82 Table 15-5: OU10 Recommendati ons for Follow-Up Actions.................................................... 82 Table 16-1: Chronology of Site Events for OU11....................................................................... 85 Table 16-2: Removal Actions for OU11...................................................................................... 85

Figures

Figure 3-1 Operable Unit Boundaries Figure 7-1 OU2 Site Map Figure 8-1 OU3 Site Map Figure 9-1 OU4 Site Map Figure 10-1 OU5 AV/CZL Site Map Figure 10-2 OU5 EGWA Smelter Site Map Figure 11-1 OU6 Previous Removal Actions Figure 12-1 Post Remedial Condition OU7 and OU10 Figure 13-1 OU8 Site Map

Appendix

Appendix A Figures Appendix B Summary of Public Comments Appendix C Site PhotographsCalifornia Gulch Five-Year Report

Page v of v 

### List of Acronyms

AOC Administrative Order on Consent ARD Acid Rock Drainage ARARs Applicable or Relevant and Appropriate Requirements AV Arkansas Valley BERA Baseline Environmental Risk Assessment CD Consent Decree CDPHE Colorado Department of Public Health and Environment CERCLA Comprehensive Environmental Re sponse, Compensation and Liability Act CZL Colorado Zinc-Lead D&RG Denver and Rio Grande Railroad D&RG W Denver and Rio Gr ande Western Railroad DMR Discharge Monitoring Report EE/CA Engineering Eval uation/ Cost Analysis EPA Environmental Protection Agency ESD Explanation of Significant Differences FS Feasibility Study FTS Fluvial Tailing Site HASP Health and Safety Plan HDPE High Density PolyEthylene LCCHP Lake County Community Health Program MOU Memorandum of Understanding NCP National Oil and Hazardous Substances Pollution Contingency Plan NPL National Priorities List O&M Operation and Maintenance OCC Ore and Chemical Company OU Operable Unit PRG Preliminary Remediation Goals POC Point of Compliance PPM Parts Per Million RA Remedial Action RD/RA Remedial Design/Remedial Action RI/FS Remedial Investigation/Feasibility Study ROD Record of Decision SFS Screening Feasibility Study SPLP Synthetic Precipitation Leaching Procedure TDS Total Dissolved Solids TRV Toxicity Reference Values TSS Total Suspended Solids TVS Table Value Standards UAO Unilateral Administrative Order U.S. EPA United States Environmental Protection Agency USGS United State Geological Survey WQC Water Quality Criteria WQS Water Quality StandardsCalifornia Gulch Five-Year Report

ES-1 

### Executive Summary

The U. S. Environmental Protection Agency (EPA) Region VIII has conducted a five-year review of the remedial actions implemented at the California Gulch Site in Lake County, Colorado. The purpose of this five-year review is to determine whether the remedy at the site is protective of human health and the environment. In addition, this fi ve-year review report identifies deficiencies found during the review, if any, and identifies r ecommendations to address them.

The California Gulch Site is lo cated in Lake County, Colorado in the upper Arkansas River watershed, approximately 100 miles southwest of Denver. The site encompasses approximately 18 square miles and includes the towns of Leadville and Stringtown; various parts of the Leadville Historic Mining District; and a secti on of the Arkansas River from the confluence of California Gulch downstream to the confluence of Two-Bit Gulch. The California Gulch Site consists of the following 12 Operable Units (OUs):

OU1 - Yak Tunnel/Water Treatment Plant OU2 - Malta Gulch Fluvial Tailing/Leadvill e Corp. Mill/Malta Gu lch Tailing Impoundments OU3 - Denver & Rio Grande Railroad (D&RG) Sl ag Piles/Railroad Ea sement/Railroad Yard OU4 - Upper California Gulch OU5 - Asarco Smelters/Slag/Mill Sites OU6 - Starr Ditch/Penrose Dump/Stray Horse Gulch/Evans Gulch OU7 - Apache Tailing Impoundments OU8 - Lower California Gulch OU9 - Residential Populated Areas OU10 - Oregon Gulch OU11 - Arkansas River Valley Floodplain OU12 - Site Water Quality

This is the third five-year review of the California Gulch Site. The trigger action for this review is the completion of the second five-year revi ew on September 29, 2001. Due to the fact that hazardous substances, pollutants, or contaminants re main at the site above levels that allow for unrestricted use and unlimited exposure, a nother five-year review is required.

Remedies have not been completed in OUs 5, 6, and 11. In addition, a re cord of decision (ROD) has not been released for OU12. Therefore, th ese OUs were not formally assessed under the Five-Year Review although a summary of progress to date and potential issues of concern is provided in the body of the Report. Remaini ng OUs were subjected to a comprehensive performance review.

Remedies are being monitored and maintained as required and generally are performing as intended. The primary issue of c oncern identified in this Five-Y ear Review is the lack of adequate land use controls (institutional contro ls (ICs)) to ensure future remedy protectiveness. In some instances ICs are required under RODs but have not been implemented, as is the case with OUs 7 and 8. In other instances, ICs are n ecessary to ensure long-te rm protection but were not required under the ROD, as is the case in OUs 3, 4 and 10.California Gulch Five-Year Report

ES-2 Operable Unit 2 may also require the developmen t and implementation of additional ICs. Several waste features were operated under an active mining permit until November of 2005 when the permit expired. The Colorado Division of Reclamation Mining and Safety (DRMS) initiated a bond forfeiture with the permitee, Leadville Corp oration, for the reclama tion of OU2 facilities operated under the permit. In accordance with the ROD, risks remaining after reclamation will be assessed by EPA and the need for additional response actions (including ICs) will be evaluated.

An Institutional Control Overlay (ICO) Districtwas established to meet most of the RODrequired land use restriction requirements. Howe ver, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedies.

Other issues identified in this Five-Year Review specific to individual OUs include:

OU1 The Yak Tunnel improvements, including the bul khead and monitoring network reportedly are operating as intended. However, the presence of rising water levels in the upper reach es of the tunnel indicates the presence of a blockage with in the tunnel. Mitigation measures have been implemented in accordance with Monitoring and Contingency Plans as intended by the decision documents. Water levels in the Yak Tunnel s hould be carefully monitored to determine effectiveness of mitigation measures and to minimize the potential for a sudden release of impounded water.

OU2 The 2004 monitoring report identified numerous areas with sparse to no vegetation on the Malta Tailing Impoundment. Minimal vege tation success and the presence of invasive plant species were identified at the Malta Gu lch Tailing (HECLA fac ility). EPA attributed this condition to recent drought conditions. Mitigation will be performed should the condition persist during the summer of 2007. In addition, settlement funds fo r operation and maintena nce of the remedy are exhausted and use Superfund res ources is not feasible. Therefor e, the funding for operation and maintenance requires clarification.

OU6 Control of water levels in the Leadville Mine Drainage Tunnel (LMDT) as required under the ROD was intended to mitigate environmental and othe r risks associated with acid rock drainage (ARD) currently impounded behind one or more suspected blockages in the LMDT. Until the selected remedy is fully implemented, risks asso ciated with this suspected “mine pool” remain. These risks include migration of ARD away from the mine pool into mine workings, natural fractures/faults with potential discharge to alluvial groundwater a nd/or springs and seeps. There also remains some concern about a sudden rel ease of ARD at the LMDTs portal should suspect blockage(s) in the LMDT fail.

OU8 The 2005 Inspection Report identifie d areas of limited vegetation at FTS-1 and Non-Residential Soils Areas and recommended additional seed and fertilizer. No documentation exists indicating whether maintenance had been performed. In addition, the condition of FTS-2 suggests that the tailings are vulnerable to erosion and remain a source for metal loading to California Gulch. Therefore, the affected portion of these remedies requires repair or replacement in order to meet the intent of the decision documents.California Gulch Five-Year Report

ES-3 OU9 An ICO District was established to satisfy R OD required ICs. However, the ICO District was repealed by Lake County in 2006. As a result, con cerns remain regarding protectiveness of the remedy. In addition, no Operation and Maintenance Pl an is in place for remediated properties in OU9. EPA continues to negotiate with Lake County towards adoption of the LCCHP as a formal IC. Implementation of an operation and maintena nce plan will also be resolved through discussions between EPA and Lake County.

OU10 RAO’s articulated in the ROD requiring, among othe r things, control of leaching and migration of metals from contaminated materials into the surface water, may be not have been achieved to the degree originally intended. This is indicated by metal loading and concentration trends at a surface water monitoring station in Oregon Gulch for the period 1995 through 2005. The frequent appearance of contaminated seepage from the toe of the c onstructed embankment may be indicative of lower than exp ected performance of the cover sy stem installed on the tailings. This situation will require continued monitoring before a final determination of protectiveness would be made.

This Site required on-going five-year review s in accordance with CERCLA §121(c). The next five-year review for the Californi a Gulch Site will be performed five years from the date of completion of this review.California Gulch Five-Year Report

ES-4 

### Five-Year Review Summary Form

SITE IDENTIFICATION

Site name: California Gulch

EPA ID: COD980717938 Region: VIII State: CO City/County: Lake County

SITE STATUS

NPL status: Final Partial Deletion Other (specify)

Remediation status (choose all that apply): Unde r Construction Operating Complete Multiple OUs? YES Construction completion date: Not Identified Has site been put into reuse? Partial

REVIEW STATUS

Reviewing agency: EPA

Name: Rebecca Thomas

Title: Remedial Project Manager Affiliation: EPA Review period: 8/06 through 9/07 Date(s) of site inspection: 08/24/2006 Type of review: Statutory Review number: 3 Triggering action: Previous Five-Year Review Report

Triggering action date: 9/28/01

Due date (five years after triggering action date) : 9/28/06

[“OU” refers to operable unit.]California Gulch Five-Year Report

ES-5 

### Five-Year Review Summary Form, cont’d

Issues:

Operable Unit Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy

2, 3, 4, 7, 8 and 10 Additional institutional controls (ICs) are or may be needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. No Yes

1 Rising water levels in upper portion of Yak Tunnel. No Yes

1 Financial assurance for continued operation of the Yak Treatment Plant has not been established. No Potentially

2 Settlement funds have been exhausted and use of Superfund resources is not permitted. No No

2 Vegetation in need of maintenance. No Yes

6 Delay in establishing control of the Mine Pool Potentially Potentially

8 A portion of Non-Residential Soils Areas, Fluvial Tailing Site (FTS) No. 1 and FTS-2 remedies in need of repair or replacement. Yes Yes

9 An ICO District was establis hed to satisfy ROD required ICs. However, the ICO Distri ct was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedy. Yes Yes

9 Isolated areas of soils in outlying potions of OU9 were identified as containing arseni c at levels that exceed the upper range of plausible action levels for residential land use. The arsenic exceedences occurred where the corresponding lead concentrat ion was below the residential action level. Therefore, it is possible that unacceptable exposure of sensitive populations might occur should these areas be developed. No Potentially

9 No O&M Plan exists for remediated properties Yes Yes

10 Additional seeps have been identified in the toe and downgradient from the impoundment. Yes YesCalifornia Gulch Five-Year Report

ES-6 

### Five-Year Review Summary Form, cont’d

Recommendation and Follow-up Action:

OU Issue Recommendation for Follow-Up Party Responsible Due Date

2 Additional ICs may be needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Investigate the impacts of mine permit expiration on remedy protectiveness and develop/ implement ICs, as necessary. CDPHE 12/08

3, 4, and 10 Institutional controls are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Prepare an ESD identifying appropriate ICs and implement the controls. Resurrection UPRR EPA 12/08

7 and 8 Institutional controls are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Develop and implement ICs. ASARCO/Res urrection 12/08

1 Rising water levels in upper portion of Yak Tunnel. Monitor effectiveness of dewatering of the Black Cloud Mine. ASARCO Res-ASARCO On-going

1 Financial assurance for continued operation of the Yak Treatment Plant has not been established. Establish financial assurance ASARCO Res-ASARCO 12/07

2 Settlement funds have been exhausted and use of Superfund resources is not permitted. Funding of operation and maintenance requires clarification. EPA/CDPHE 12/08

2 Vegetation in need of maintenance. Perform maintenance as required following the next scheduled annual inspection. Responsibility for O&M requires clarification 12/07

6 Delay in establishing control of the Mine Pool Perform remedial action EPA Re-evaluateat next fiveyear review

8 A portion of Non-Residential Soils Areas, Fluvial Tailing Site (FTS) No. 1 and FTS-2 remedies in need of repair or replacement. Modify/repair the existing remedies, as necessary, so that vegetation is established and/or mine waste does not come into contact with California Gulch flows or allow precipitation to pond on the tailing surface. Resurrection 12/07California Gulch Five-Year Report

ES-7 

### Five-Year Review Summary Form, cont’d

Recommendation and Follow-up Action:

OU Issue Recommendation for Follow-Up Party Responsible Due Date

9 An ICO District was established to satisfy ROD required ICs. However, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedy. Formalize ICs EPA/Lake County 12/08

9 Isolated areas of soils in outlying potions of OU9 were identified as containing arsenic at levels that exceed the upper range of plausible action levels for residential land use. The arsenic exceedences occurred where the corresponding lead concentration was below the residential action level. Therefore, it is possible that unacceptable exposure of sensitive populations might occur should these areas be developed. Consider creation of an IC to address areas of elevated arsenic in soils where development may result in unacceptable exposure of sensitive populations

EPA/Lake County 12/08

9 No O&M Plan exists for remediated properties Prepare and implement an O&M Plan EPA/Lake County 12/08

10 Additional seeps have been identified in the toe and downgradient from the impoundment. Continue to monitor potential for seeps from the toe of and downgradient from the impoundment. Resurrection On-goingCalifornia Gulch Five-Year Report

ES-8 

### Five-Year Review Summary Form, cont’d.

Protectiveness Statement(s) for ea ch OU is provided below:

OU1 – Yak Tunnel

The remedy is currently protective of human health and the environment. However, mitigation of rising water levels caused by a suspected blockage in the Yak Tunnel through dewatering via the Black Cloud Mine should be carefully monitored to determine effectiveness.

OU 2 - Malta Tailing Impoundment, Malta Gulch Tailing Impoundment and Lower Malta Gulch Fluvial Tailing and OU 3 - Denver & Rio Grande Railroad (D&RG) Slag Piles/Railroad Easement/Railroad Yard

The remedy is currently protective of human health and the environment.
The absence of ICs to preclude disturbance of the remedy under current zoning has not impacted past or current protectiveness as the remedies were undi sturbed at the time of this Five-Year Review. However, the potential exists for future impacts on remedy protectiveness if such an institutional control is not developed and implemented. EPA and CDPHE are informally notified by the County of any chan ges in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalized

.

Operable Unit 4 - Upper California Gulch

The remedy is currently protective of human health and the environment. However, future remedial work may be required in order to attain final Site-wide wate r quality standards as determined pursuant to OU12.
The absence of ICs to preclude disturbance of the remedy under current zoning has not impacted past or current protectiveness as the remedies were undi sturbed at the time of this Five-Year Review. However, the potential exists for future impacts on remedy protectiveness if such an intuitional control is not developed and implemented. EPA and CDPHE are informally notified by the County of any chan ges in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalized

Operable Unit 5 - Asarco Smelters/ Colorado Zinc-Lead Mill Site

Remedial work at the Arkansas Valley Smelter and Colora do Zinc-Lead Mill is incomplete. Therefore, the remedy is not yet protective although overall protectiveness is expected to be achieved once remedial construction is completed.
The absence of ICs to preclude disturbance of the remedy under current zoning has not impacted past or current protectiveness as the remedy remains incomplete. However, the potential exists for future impacts on remedy protectiveness if such an intuitional control is not developed and implemented. EPA and CDPHE are informally notified by the County of any changes in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalizedCalifornia Gulch Five-Year Report

ES-9 

### Five-Year Review Summary Form, cont’d.

Protectiveness Statement(s) for ea ch OU is provided below:

Operable Unit 6 - Starr Ditch/Penros e Dump/Stray Horse Gulch/Evans Gulch

The remedy is currently protective of human health and the environment. However, future remedial work may be required in order to attain final Site-wide wate r quality standards as determined pursuant to OU12.
The absence of ICs to preclude disturbance of the remedy under current zoning and to identify properties where special precautions may be necessary has not impacted past or current protectiveness as the remedies were undisturbed at the time of this Five-Year Review. Howeve r, the potential exists for future impacts on remedy protectiveness if such an IC is not developed and implemented. The selected remedy will address the mine pool.

Operable Unit 7 - Apache Tailing Impoundments

The remedy is currently protective of human health and the environment. However, future remedial work may be required in order to attain final Site-wide wate r quality standards as determined pursuant to OU12.
The absence of ICs to preclude disturbance of the remedy under current zoning has not impacted past or current protectiveness as the remedies were undi sturbed at the time of this Five-Year Review. However, the potential exists for future impacts on remedy protectiveness if such an IC is not developed and implemented.

Operable Unit 8 - Lower California Gulch

Although the remedy is currently considered to be protective of human health and the environment, the poor condition of FTS-2 remedy requires repair or replacement in order to meet the intent of the decision documents. In addition, future remedial work may be required in orde r to attain final Site-wide water quality standards as determined pursuant to OU12.
The absence of ICs to preclude disturbance of the remedy under current zoning has not impacted past or current protectiveness as the remedies were undi sturbed at the time of this Five-Year Review. However, the potential exists for future impacts on remedy protectiveness if such an IC is not developed and implemented. EPA and CDPHE are informally notified by the County of any changes in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalized.

Operable Unit 9 - Populated Residential Areas

The remedy is protective of human health and the environment.

Performance standards for OU9 were met in March 2006 as a result of the LCCHP. Given that hazardous substances remain within OU9, operation and ma intenance of the LCCHP is necessary to ensure the protectiveness of the remedy

.

Operable Unit 10 - Oregon Gulch

The remedy is protective of human health and the environment. However, future remedial work may be required in order to attain final Site-wide water quality standards as determined pursuant to OU12.
The absence of ICs to preclude disturbance of the remedy under current zoning has not impacted past or current protectiveness as the remedies were undi sturbed at the time of this Five-Year Review. However, the potential exists for future impacts on remedy protectiveness if such an IC is not developed and implemented. EPA and CDPHE are informally notified by the County of any changes in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalized.California Gulch Five-Year Report

ES-10 

### Five-Year Review Summary Form, cont’d.

Protectiveness Statement(s) for ea ch OU is provided below:

Operable Unit 11- Arkansas River Valley Floodplain

The remedy for Operable Unit 11 (OU11) selected in the 2005 ROD has not been implemented.

Operable Unit 12

Operable Unit 12 covers the entire California Gulch s ite and was designated to address Site-wide surface and groundwater. Under the provisions of the 1994 CD, OU12 will be addressed after completion of source remediation in OUs 2 through 10. This will include a determinati on of protectiveness of surface and groundwater and the establishment of points of comp liance and performance standards.

The OU12 Remedial Investigation and Feasibility Study were underway at the time of this Five-Year Review with a ROD anticipated to be released in 2008

.

Other Comments:

NoneCalifornia Gulch Five-Year Report

Page 1 of 89 

### Five-Year Review Report

1.0 Introduction

Purpose of the Review The purpose of five-year reviews is to dete rmine whether remedies implemented at the California Gulch National Priority List (NPL) S ite (the Site) in Lake County, Colorado are protective of human health and the environmen t. The methods, findings and conclusions of reviews are documented in Five-Year Review re ports. In addition, Five-Year Review reports identify issues found during the review, if any, and recommendations to address them.

This is the third five-year review for the Site. The triggering action for this review is the previous Five-Year Review report, signed on Septmb er 29, 2001. Because hazardous substances, pollutants or contaminants remain at the Site above levels that allow for unlimited use and unrestricted exposure, a Statutory Five-Year Review is required.

Authority for Conducting the Five-Year Review The U.S. Environmental Protection Agency (EPA) is preparing this five-year review pursuant to CERCLA §121 and the National Continge ncy Plan (NCP). CERCLA §121 states:

If the President selects a remedial action that results in any hazardous substances, pollutants, or contaminants remaining at the site, the President shall review such remedial action no less often than each five years after the initiation of such remedial action to assure that human health and the environment are being protected by the remedial action being implemen ted. In addition, if upon such review it is the judgment of the President that action is appropriate at such site in accordance with section [104] or [106], the President shall take or require such action. The President shall report to the Congress a list of facilities for which such review is required, the results of all such reviews, and any actions taken as a result of such reviews. The EPA interpreted this requirement further in the National Contingenc y Plan (NCP); 40 CFR §300.430(f) (4) (ii) states:

If a remedial action is selected that results in hazardous substances, pollutants, or contaminants remaining at the site above levels that allow for unlimited use and unrestricted exposure, the lead agency sha ll review such action no less often than every five years after th e initiation of the select ed remedial action.

Who Conducted the Five-Year Review EPA Region 8 conducted the Five-Y ear Review of remedial actions implemented for Operable Units 1 through 11 at the Site in and around Le adville, Colorado. This review was conducted from September 2006 through September 2007. This report documents the results of the review

. HDR Engineering, Inc. (HDR) of Denver, Colora do was retained under a subcontract to Project Resources Inc. (PRI) to prepare this Five-Year Review Report for EPA. PRI was retained by the US Army Corps of Engineers, Omaha District under a Rapid Response Program contract.California Gulch Five-Year Report

Page 2 of 89 2.0 Site Chronology

Table 2-1 presents a chronology of activities at the Site.

Table 2-1 Chronology of Activities at California Gulch Site

Date Event 1859 Placer gold discovered in California Gulch and mining began in the District. 1877-1893 The Harrison Reduction Works in Operable Unit (OU) 3, the only smelter reported to have processed gold ores, opened on the northeast co rner of Harrison Avenue and Elm Street in 1877, but closed in 1893. 1878-1882 The Grant Smelter operated from 1878 to 1882. 1878-1887 Berdell and Witherell Smelter operat ed near the La Plata slag pile in OU3. 1879-1882 Area comprising OU2 developed with placer claims. 1879-1886 The Cummings and Finn Smelter Works began operations at Big Evans Gulch in OU3 1879. The plant, which also operated under the name of the Fryer Hill Smelting Company was dismantled in 1886. Other smelters that operated in the Big Evans Gulch Area included the Ohio and Missouri Smelter, the Gage-Hagaman Smelter, and the Raymond, Sherman, and McKay Smelter. 1879-1903 The Elgin Smelter operated intermittently from 1879 until 1903. 1879-1961 The Elgin, Grant, and Arkansas Valley Smelters in OU5 were constructed. The Arkansas Valley Smelter processed lead ore and reproce ssed slag to produce lead, silver, and other metals and operated until 1961. 1882-1960 Arkansas Valley Smelter operated in OU5. 1892-1900 The Union Smelter operated from 1892 to 1900.1892-1900 Bimetallic Smelting Company leased the La Plata area in OU3 for pyritic smelting of lowgrade ores. 1893-1902 The Elgin Smelter works in OU5 were leased and operated by several different companies. 1895 Yak Tunnel driven to dewater mines and to facilitate mineral exploration and development in OU1. 1900 American Smelting and Refining Company purchased the La Plata works in OU3 in 1900. 1914-1926 The Western Zinc Mining and Reducing Company constructed a smelter to the west of the City of Leadville in OU5 that extracted zinc from ores. 1917 Harrison Recovery Works was established to rework the Harrison Street slag pile in OU3. 1923 Last extension to Yak tunnel occurred - total length of tunnel measures 3-1/2 to 4 miles into Iron Hill and Breece Hill in OU1. 1925-1940 The Colorado Zinc and Lead (CZL) site operated a flotation mill that processed zinc-lead ores sporadically between 1925 and 1940. The tailing impoundment at the CZL site is the only fluvial tailing impoundment in OU8. 1926-1938 In 1926, the Colorado Zinc-Lead Mill in OU5 began processing ores with a custom flotation process to produce zinc, lead, gold, silver, and so me copper concentrations. The mill closed in 1930, but was remodeled in 1935. Between 1935 and 1938, when it closed for good, the mill processed ores from several local mines and waste dumps. The history of the Arkansas Valley South Hillside Slag Pile is unknown. It is possible that either the Arkansas Valley or the Grant/Union Smelters disposed of slag at this site. 1939-1956 The mill that generated the tailing placed in the Main Impoundment, and possibly the North Impoundment in OU7, was located on the hillsid e northeast of the North Impoundment. This mill was known as the Venir Mill, the Calif ornia Gulch Mill, and the ASARCO Leadville Milling unit. 1945-1957 The Oregon Gulch Tailing Impoundment in OU10 received tailing from the ResurrectionASARCO mill in California Gulch. 1943-1946 Ore & Chemical Company (O CC) used OU2 as a disposal site.California Gulch Five-Year Report

Page 3 of 89 Table 2-1, cont’d Chronology of Activities at California Gulch Site

Date Event 1947-1987 Hecla Mining Company, which later purchased Day Mines (Hecla/Day), leased OU2 property. 1961 D&RGW purchased the Arkansas Valley (AV) slag pile in OU3 from ASARCO for use as ballast. 1968 Leadville Corporation purchased OU2 property. 1970 D&RGW purchased the La Plata slag pile in OU3 from the Leadville Sanitation District in 1970. 1970s-1980s The Apache Mill began operations in the late 1970s and continued operations into the 1980s. 1970s-1986 A mill facility utilized a cyanide leach process to extract silver from ore obtained from the Sherman and Diamond Resurrection mines. The mill was purchased by the Leadville Corporation in the early 1980's and continued operations until the mill closed in 1986. 1983 D&RGW purchased the Harrison Street Slag Pile in OU3 from NL Industries for use as a ballast production. 1983-1988 Leadville Silver & Gold operated a pyrite recovery process on OU2. 09/08/83 California Gulch site placed on NPL.

1992 Yak Water Treatment Plant begins treated Yak Tunnel discharge 1994 Sitewide Consent Decree 02/02/96 First Five-Year Review

04/01 OU10 deleted from NPL 06/01 OU2 deleted from NPL 09/28/01 Second Five-Year Review 1988 - 2005 Records of Decision were signed for OU1, OU2, OU3, OU4, OU5, OU6, OU7, OU8, OU9, OU10 and OU11. 1994-2006 Various response actions performed by parties to the Consent DecreeCalifornia Gulch Five-Year Report

Page 4 of 89 3.0 Background

Location and Setting The Site is comprised of approximately 18 squa re miles (see Figure 3-1, Appendix A) in Lake County, approximately 100 miles southwest of De nver. It includes the towns of Leadville and Stringtown, various parts of the Le adville Historic Mining District, and a section of the Arkansas River from the confluence of California Gulch do wnstream to the confluence of Two-Bit Gulch Creek.

The elevation of the Site range s from 9,300 feet at the confluen ce of Two-Bit Gulch and the Arkansas River at the southwes tern boundary of the site to over 12,000 feet near Ball Mountain east of Leadville, Colorado.

The Site includes, but is not limited to, the City of Leadville. The area is a predominantly rural county with a population of 7,812 (United States Bureau of the Census, 2000). The zoning uses for the area are industrial/mining, commerc ial, recreational, and residential.

Site History and Nature of Contamination The Site has been the location of mining, minera l processing, and smelting activities that have produced gold, silver, lead, and zinc for more than 140 years. Mining activities in Leadville began in 1859 when gold bearing placer deposits were found along California Gulch. Since that time, mining activity has almost been c ontinuous, although there have been production cessations or slowdowns because of economic conditions or labor issues. An estimated 26 million tons of ore were produced in the L eadville Mining District from 1859 through 1986. Nearly all of the mines within the Site presentl y are inactive, and all of the mills and smelters have been either decommissioned or demolished.

Numerous mining methodologies were used at the Site including placer mining, exposed fissure veins, and underground mining. Waste rock was excavated and left near the mine entrances while metal ores were processed by crushing, milling, and smelting resulting in the generation of several different types of waste. The types of waste generated as a result of mining activities are described below:

• Waste Rock Piles- Waste rock removed from underground workings was placed near mine entrances. This waste rock often cont ains elevated levels of heavy metals and sulfide minerals. In the presence of water, su lfide minerals can generate acid that lowers the pH of the water. This low pH water pr omotes the leaching of heavy metals from the rock and into surface and groundwater.

• Slag and other Smelter Wastes - In the smelters, high-grad e ores were refined and concentrated into higher-grade products. Wa ste products from the smelters include slag flue dust and stack emissions all containing heavy metals. Contaminants in smelter stack emissions often commingled with soils as pa rticulates settled out of the atmosphere. There were forty-four known smelters in the district.California Gulch Five-Year Report

Page 5 of 89 • Acid Rock Drainage - Groundwater, which began flooding into the mines, produces acid rock drainage. This process brought oxygen in contact with the pyritic ores. These materials, when oxidized, break down and alte r the sulfide minerals to form acid rock drainage (ARD) water that has low pH leve ls. This low pH water leaches heavy metal constituents from rocks and into surface water runoff.

• Mill Tailing - At mills on the Site, ores were crushed and separated into metallic concentrates and waste products by physical pr ocesses. Metallic con centrates were then shipped elsewhere or further processed at a smelter in the area. Waste products (mill tailing) were generally placed in nearby tailing ponds. Release of contaminants from tailing material can be attributed to seep age from existing tailing deposits and from fluvially deposited tailing. Release of solubl e inorganic metals contained in runoff from tailing deposits and contained in seeps eman ating from the toe of some tailing deposits have contributed to metal contamination of sediments and surface water.

More than 2,000 mine waste piles have been identified in the Site that are associated with the estimated 26 million tons of ore produced over th e history of operations. A few of these waste piles are located within the residential areas of Leadville and Stringtown. Contamination of soil and surface water drainage in popul ated areas occurs throughout th e Site with large amounts of water being treated by on- and off-Site water treatment facilities.

Groundwater and surface water studies were con ducted by private parties, as well as by the United States Geological Survey (USGS) and EP A. The initial Phase I of the Remedial Investigation (Phase I RI) was released by U.S. EPA in May 1987, with subsequent Remedial Investigation/Feasibil ity Studies (RI/FS) performed by W oodward-Clyde in 1990 and 1991. The 1987 Phase I RI indicated that surface water in Ca lifornia Gulch exceeded primary drinking water standards for lead and cadmium and that th e site surface water contained cadmium, copper, lead, and zinc at levels that exceeded water qualit y criteria. Additionally, soils at the site were found to contain elevated levels of arsenic, zinc, lead, copper, and cadmium.

Summary of Baseline Risk Assessment
Baseline human health risk assessments (BRAs) characterized baseline risks at the Site. Riskbased numerical clean-up goals were also establ ished for the entire populated area as a function of land use. A summary of Site risks and numerical clean-up goals as well as an assessment of their validity at the present time is discussed below.

Under the 1994 CD, assessment of Site-wide surface and groundwater quality relative to appropriate performance standards was deferred to OU12. A ROD for OU12 setting final surface and groundwater performance standa rds has not been developed (sch eduled to be released in 2007). Therefore, Site risks and associated numerical clean-up goals applicable to the OUs subject to this Five-Year Review are limited to soils and mine wastes (solid media).California Gulch Five-Year Report

Page 6 of 89 A number of BRAs have been completed fo r the NPL Site, and are listed below:

• Preliminary Human Health Baseline Risk Assessment for the California Gulch NPL Site (Weston, 1991). The presence of elevated le vels of heavy metals in soils in and around the residential and comme rcial areas of Leadville was discovered during early site investigations. This information was used in the preliminary risk assessment, which indicated that contaminant levels we re high enough to be of potential human health concern. Lead and arsenic were identi fied as the primary chemicals of potential human health concern.

• Baseline Human Health Risk Assessment for the California Gulch Superfund Site. Part C: Screening Level So il Concentrations for Worke rs and Recreational Site Visitors Exposed to Lead and Arsenic (Weston, 1995).

3⁄4 Baseline Human Health Risk Assessment for the California Gulch Superfund Site. Part C: Evaluation of Worker Scenario. This part of the BRA was conducted to evaluate risks to current or future work ers in the commercial and business district of the community. This study focused on th e risks associated with exposure to lead and arsenic in soil and dust through i ngestion. The study concluded that risks to current workers from lead and arsenic ar e likely to be below a level of concern. The study further concluded that some uncer tainty exists regarding the magnitude of potential future risks as well as the potential for unacceptable current risks in specific sublocations within the Site.

3⁄4 Baseline Human Health Risk Assessment for the California Gulch Superfund Site. Part C: Evaluation of Recreational Scenarios. This part of the BRA was conducted to evaluate risks which envir onmental contamination poses to people who engage in recreational activities (hunting, hiking, bike riding, picnicking, etc.) in areas in and around the comm unity. This study focused on the risks associated with lead and ar senic at the site. The study c oncluded that average lead levels are generally below that recr eational action level for areas where recreational scenarios are considered likely.

• Final Baseline Aquatic Ecological Risk Asse ssment for the California Gulch NPL Site (Weston, 1995). The Aquatic Ecological Risk Assessment evaluated the impact of mine waste contamination on the aquatic ecosy stem in the NPL Site. The mine wastes in the area are associated with increased heavy metal loading to the surface water and sediments within the site dr ainages and the Arkansas Rive r. The study concluded that discharges of metals from California Gulc h continued to result in conditions (in the Arkansas River) that were of concern, especially near the confluence.California Gulch Five-Year Report

Page 7 of 89 • Baseline Human Health Risk Assessment for the California Gulch Superfund Site. Part A – Risks to Residents from Lead (Weston, 1996). This document focuses on the risks of lead exposure to young children (age 0-6 years). Young children were selected as the focus because they typically have higher intake rates of environmental media per unit body weight than adults, they tend to absorb a higher fraction of ingested lead than adults, and they tend to be more susceptible to some of the adverse effects of lead than adults. The EPA used Site-specific inputs to an integrated exposure, uptake, and biokinetic model al ong with structural equation modeling of empirical blood lead and environmental lead data, to assess risk to residents from lead. The study concluded that residential le ad exposure may result in adverse health effects above a level of concern.

• Baseline Human Health Risk Assessment for the California Gulch Superfund Site. Part B – Risks to Residents fr om Contaminants other than Lead (Weston, 1996). This document focuses on risks to current a nd future residents of Leadville from environmental media contaminated with mi ne related wastes other than lead. The assessment adopted a Preliminary Remedia tion Goal (PRG) approach to the risk analysis where a concentration for each contaminant of potential concern (COPC) was identified using a specific level of health risk for each medium. This PRG was then compared to site-wide data to de termine if, where, and by how much site concentrations exceed the calculated value. This study concluded that non-lead metals in surface soils do not pose a signif icant health risk to residents.

Human Health Risks
As discussed above, Part B of the Human Health Risk Assessment concluded that there are no locations on the Site where antimony, barium, cadmium, beryllium, chromium, copper, mercury, nickel, silver, thallium, or zinc are of significant concern in so ils. The risk assessment also concluded that risk exceedences are small for ar senic and manganese and occur only in the most conservative risk calculations. This, combined with the recognition that assumed uptake (bioavailability) of metals used in risk calcu lations may be higher than actual, lead to the conclusion that non-lead metals in surface soils do not pose a significant health risk to residents. Thus, the only contaminant of concern is lead.

To evaluate risk, calculations were performed to identify concentrations (action levels) of lead in soil that were of potential c oncern. The land use-based reme diation goals are summarized in Table 3-1.

Table 3-1 Land Use-Based Remediation Goals
Land Use Lead Remedial Goal (mg/Kg) Reference

Recreational 16,000 BRA Part C

Worker 6,100-7,700 Plausible Action Levels; BRA Part C Residential 3,500 BRA Part A and OU9 RODCalifornia Gulch Five-Year Report

Page 8 of 89 In order to identify areas where land use-based remediation goals might be exceeded, the goals were compared to findings of soil concentration values in previous Remedial Investigations (RIs). Average lead levels over an exposure area are compared to the soil remediation goal. Occasional measurements of c oncentrations above the remedi ation goal do not necessarily constitute evidence that an area is unsafe.

Inspection of the prior RIs shows that average lead levels are generally well below the action level of 16,000 milligrams per Kilogram (mg/Kg) for areas where recreational scenarios are considered likely. For the worker scenario, the average lead levels are mostly below the centraltendency range of plausible action levels (6100-7700 mg/Kg) for most areas zoned for commercial land use, with the possible exception of some areas in the historic mining area east of town and in the vicinity of the form er AV Smelter located southwest of town. Soil samples collected subsequent to the Human Health Risk Assessment in support of deletion activities, identified several isolated areas where arsenic concentrations exceeded the upper range of plausible action levels for residential land use (120-340 mg/Kg; BRA Part B). The arsenic exceedences occurred where the corresponding l ead concentration was below the residential action level of 3,500 mg/Kg. These isolated areas are located in outlying, undeveloped portions of OU9 (Populated Areas).

Current Validity of COC List and Remediation Goals Exposure assumptions, toxicity values and other inputs to the risk assessment have not been revised so as to result in any new COCs. In addition, the Lake County Community Health Program (LCCHP) 2005 Annual Report concludes that remedial action objectives established by EPA for OU9 (Populated Areas) have been me t in 2005. This conclusion was based on an evaluation of the Program in accordance with the established performance standards expressed as goals for blood lead levels in children. Given that these objectives have been met, it is reasonable to conclude that remediation goa ls for lead described above remain protective of human health. This is also discussed in Section 14.0 (OU9).

The exposure assumptions and toxicity data used to develop range of plau sible action levels for arsenic, published in the Human Heath Ri sk Assessment (Part B), remain valid.California Gulch Five-Year Report

Page 9 of 89 4.0 Administrative Components and Community Involvement

Administrative Components This is the third five-year review for the Site . The five-year review was led by Rebecca Thomas, EPA Remedial Project Manager for the Site. Th e following Team Members participated in the review:

3⁄4 Rebecca Thomas, EPA Remedial Project Manager 3⁄4 Stan Christensen, EPA Re medial Project Manager 3⁄4 Jennifer Lane, Community Involvement Coordinator 3⁄4 Richard Sisk, EPA Attorney 3⁄4 Doug Jamison, CDPHE Project Manager

EPA Contractors:
3⁄4 Kenneth Napp, HDR Engineering, Inc.

This five-year review consisted of the followi ng activities: a review of relevant documents; interviews with technical personn el in public and private practice as well as elected officials and the public; data review; and a site visit. The sc hedule for the review extended through December 2006.

Community Involvement A notice that the five-year review was in progre ss was placed in the Leadville Herald Democrat and Leadville Chronicle on August 24, 2006. The noti ce invited members of the public to submit their questions or comments re garding the review to EPA.

A notice of the completion of the five-year review report will be placed in the local newspaper. The completed report is available in the Lake County Public Library, located in Leadville Colorado and in the EPA Superfund R ecords Center in Denver, Colorado.

U.S. EPA Region 8 Records Center 999 18th Street (3rd Floor South Tower) Denver, CO 80202

(303) 312-6473 Interviews

Interviews were conducted w ith 17 community members repr esenting city and county government, the county’s advisory group, the count y health department, the Colorado Mountain College, potentially responsible parties, and citiz ens. Most of the interviews occurred one-onone with the exception of one meeting with six representatives of the County’s Institutional Control Advisory Group and three telephone in terviews. The Lake County Commissioners requested that they provide information in writin g, so their concerns are reflected in the summary that follows and their written account is included with the appendixes of the Five-year Review.California Gulch Five-Year Report

Page 10 of 89 EPA received numerous comments that do not dir ectly pertain to the protectiveness of remedy operations at the Site. These comments are important and EPA will use them to develop an update of the Community Involvement Plan at a future date. A written summary of responses from interviews and from the Lake County Commissioners written comments for each of interview questions is provided in Appendix B.California Gulch Five-Year Report

Page 11 of 89 5.0 Operable Units

The Site is divided into twelve media and/or geographically-based OUs . Records of Decision have been completed for 11 of the 12 OUs. Th e Site OUs are listed below and identified on Figure 3-1 (Appendix A).

OU1 - Yak Tunnel/Water Treatment Plant OU2 - Malta Gulch Fluvial Tailing/Leadville Corp. Mill/Malta Gulch Tailing Impoundments OU3 - Denver & Rio Grande Railroad (D&RG) Slag Piles/Railroad Easement/Railroad Yard OU4 - Upper California Gulch OU5 - Asarco Smelters/Slag/Mill Sites OU6 - Starr Ditch/Penrose Dump/Stray Horse Gulch/Evans Gulch OU7 - Apache Tailing Impoundments OU8 - Lower California Gulch OU9 - Residential Populated Areas OU10 - Oregon Gulch OU11 - Arkansas River Valley Floodplain OU12 - Site Water Quality

A Consent Decree (CD) was executed in 1994 between EPA, State of Colorado and the following Responsible Parties:

• ASARCO Corporation (ASARCO)

• Joint Venture between ASARCO and Resu rrection Mining Company (Res-ASARCO)

• Resurrection Mining Company and its parent , Newmont Mining Company (Resurrection)

The CD specified that RODs selecting response actions to effect source remediation would be implemented before a ROD is issued for OU 12. The ROD for OU12 w ill address site-wide surface water and groundwater. The ROD for OU12 is scheduled for release in 2008.California Gulch Five-Year Report

Page 12 of 89 6.0 Operable Unit 1-Yak Tunnel/Water Treatment Plant

6.1 Description

Operable Unit 1 consists of the Yak Tunnel a nd Water Treatment Plant. The Yak Tunnel was constructed to dewater mines and to facilitate mineral explorati on and development. The tunnel was driven in 1895, as an extension of the Silver Cord Tunnel, to drain the Iron Hill mines. The Yak Tunnel was extended several times, with th e last extension occurring in 1923. The Yak Tunnel extends underground approximately 3-1/2 to 4 miles into Iron Hill and Breece Hill. The tunnel has several major laterals and drifts that extend from the tunnel into various mine workings, such as the Horseshoe , the Rubi, the North Mike, the South Mike, the Ibex No. 4, the Little Winnie, the Resurrection No. 1, the Fortune, the Resurrection No. 2, and the Dolly B. U.S. EPA estimated that 60,000 feet of tunnels and majo r laterals and 55 to 74 million cubic feet of void space are associated with the tunnel mining activities. The location of OU1 is shown on Figure 3-1 (Appendix A).

At the time of the ROD in Marc h 1988, studies indicated that a combined total of 210 tons per year of cadmium, lead, copper, manganese, iron, and zinc were discharged from the Yak Tunnel into California Gulch, which drains into the Arka nsas River. Surface water contamination is the major impact of the Yak Tunnel discharge. Sh allow alluvial groundwater and stream sediment may have been impacted by historic releases from the Yak Tunnel.

Table 6-1 lists the chronology of site events for Operable Unit 1- Yak Tunnel and Water Treatment Plant of the California Gulch site.

Table 6-1 Chronology of Site Events for OU1 Yak Tunnel and Water Treatment Plant
Date Event 09/08/83 California Gulch site placed on NPL

05/87 Phase I Remedial Investig ation (RI) report released 06/87 Feasibility Study (FS) report released 08/87 Proposed remedial action plan released for OU1 03/29/88 Record of Decision (ROD)

09/88 Began Surge Pond and Interim Treatment Plant Remedy 03/23/89 Modification of ROD based on negotiations with Respondents 03/29/89 Unilateral Administrative Order (UAO 89-20)

2/90 Began Construction of Yak Tunnel Water Treatment Facility 06/91 Completed Surge Pond and Interim Treatment Plant Remedy 10/22/91 Explanation of Significant Differences (ESD)

2/92 Completion of the Yak Tunnel Water Treatment Facility 04/30/93 First amendment to UAO 89-20 06/16/93 Second amendment to UAO 89-20

03/94 Began Yak Tunnel Bulkhead Remedy 11/94 Completed Yak Tunnel Bulkhead Remedy 5/02 Rising water levels detected in Yak Tunnel 3/06 Begin dewatering Black Cloud MineCalifornia Gulch Five-Year Report

Page 13 of 89 6.2 Response Actions

Response Action Selection/Implementation In June 1987, EPA released a FS report and in August 1987 released a proposed remedial action plan for the Yak Tunnel. EPA issued a Un ilateral Administrative Order (UAO) to ASARCO Incorporated, Newmont Mining Corporation, Re s-ASARCO Joint Venture, and Resurrection Mining Company on March 29, 1989 for the Reme dial Design/Remedial Action of the Yak Tunnel. Two amendments were made to the UAO on April 30, 1993 and June 16, 1993.

The remedies for the Yak Tunnel were initially selected in the 1988 ROD, changed in the 1989 ROD modification, and further al tered in the 1991 ESD. The final remedy consists of the following elements:

• Construction of a surge pond to capture drainage from the tunnel and to minimize the impact of surges on California Gulch and the Arkansas River.

• Installation of a permanent wa ter treatment system to tr eat contaminated groundwater from the Yak Tunnel before discharge in California Gulch

• Construction of a flow control bulkhead within the tunnel to prevent surges.

• Establishment of a surface and groundwater mon itoring system to detect leakage, seeps, or migration of contaminated groundwater.

• Development and implementation, as necessar y, of a contingency plan to address any adverse effects on surface or groundwater from tunnel m odifications or collapse.

• Inspection, operation and ma intenance of the remedy.

The Yak Tunnel Water Treatment Plant has been in operation since it’s completion in 1992.

System Operation/O&M According to the 1988 ROD, routine operation and maintenance would be required including repairing grouted areas of struct ures due to corrosion, settlement or other factors; occasional repair or replacement of monitor well pumps an d surface water monitoring equipment; repair of access roads; routine repair or replacement of pumps, motors, mixers, piping, and tankage; and inspections.

6.3 Progress Since the Last Five Year-Review

The last site-wide Five-Year review, which wa s finalized on September 29, 2001, indicated that the Water Treatment Plant met the ROD, ROD Modification, and ESD requirements; remains effective, is operating and functioning as desi gned, and is protective of human health and the environment.California Gulch Five-Year Report

Page 14 of 89 Since the last review, flows from a new contamin ated seep associated with the Oregon Gulch Tailing impoundment are now being collected an d piped to the Yak Treatment Plant. This additional action was not triggere d by decision documents associat ed with OU1. Rather, it was done to comply with decision documents for Oregon Gulch (OU10).

Additional new influent waters to the Yak Treat ment Plant include wate rs are being pumped from the Black Cloud Mine. This additional action was triggered by the provisions of the OU1 Monitoring and Contingency Plans as discusse d in the Data Review Section, below.

6.4 Five-Year Review Process

Document Review In preparing this Five-Year Review Repor t, the following documents were reviewed:

• Second Five-Year Review Report

• Additional Investigation Work Plan, Ya k Tunnel Operable Unit, MFG, June 2004

• Status Report – Yak Tunnel Risi ng Water Levels, MFG, June 2003

Interviews were conducted with the following individuals to pr ovide supplemental technical information:

3⁄4 Doug Jamison – CDPHE 3⁄4 Tim Runnels – MFG 3⁄4 Stan Christensen – USEPA 3⁄4 Rebecca Thomas - USEPA

Data Review The remedy includes a ground wate r monitoring program designed to track ground water levels and quality in and around the Yak Tunnel. The remedy also includes an effluent monitoring program for the Yak Water Treatm ent Facility. In preparing this Five-Year Review Report, data from the following reports were reviewed and evaluated:

• Monthly effluent monitoring reports for the period January 2004 through August 2006 (prepared by ASARCO and MFG).

• Quarterly Data Transmittal – Yak Tunnel Enhanced Monitoring Program, ASARCO, September 2003.

• Effluent quality monitoring frequency required under the 1988 ROD and subsequent modifications was relaxed in August 2002 from weekly to monthly with the addition of Whole Effluent Toxicity (WET) as a new analytical method. A review of monthly monitoring reports indicated that effluent qua lity has consistently met quality standards and reporting requirements required by th e ROD and subsequent modifications.California Gulch Five-Year Report

Page 15 of 89 Various Yak Tunnel monitoring repo rts (listed above) identified ri sing water levels in the upper reaches of the tunnel as well as the Black Cloud Mine indicating an apparent blockage in the upper region of the Yak Tunnel. In accordance with the provisions of the Routine Monitoring Plan and Contingency Plan (MFG, 1999), enha nced monitoring was initiated in 2002 and pumping of water from the Black Cloud Mine commenced in March 2006. Extracted water is piped to the Yak Water Treatment Plant. As a result, the Yak pl ant reportedly is operating at capacity (850 gallons per minute).

Pumping from the Black Cloud Mine is intended to lower water le vels in the Yak Tunnel above the suspected blockage. The contingency plan calls for one year of continuous pumping to assess how water levels respond.

Site Inspection The Site Inspection was performed on August 24, 2006 by the EPA Remedial Project Manager, Stan Christensen and Kenneth Napp, the HDR Project Manager. The assessment of Site conditions relied heavily on the recent observati ons of regulatory agency personnel interviewed during this Five-Year Review.

Based on the Site Inspection, c onditions documented during the last Five-Year Review and discussions with regulatory agency personnel, all physical remediation elements in OU1 have been constructed and are in working order.

6.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• The Yak Tunnel improvements, including the bulkhead and monitoring network reportedly are operating as inte nded. However, the presence of rising water levels in the upper reaches of the tunnel indicates the pr esence of a blockage within the tunnel. Mitigation measures have been implem ented in accordance with Monitoring and Contingency Plans as intended by the decision documents.

• The primary indicators of treatment plant performance are capacity and effluent quality. Capacity remains adequate to treat all waters emanating from the Yak Tunnel. Therefore, this portion of the remedy is functioning as intended by the decision documents. However, mitigation of rising water levels in the Yak Tunnel requires active pumping of the Black Cloud Mine. The pumping rate is limited by the available excess capacity of the Yak Treatment Plant (beyond the flows em anating from the Yak Tunnel). Pumping of the Black Cloud Mine began in March 2006 and it is premature to quantify the effectiveness of this mitigation method.

• A review of monthly monitoring reports indica ted that effluent quality has consistently met quality standards and reporting requireme nts required by the ROD and subsequent modifications.California Gulch Five-Year Report

Page 16 of 89 Question B: Are the exposure assumptions, toxi city data, and cleanup levels and RAOs used at the time of the remedy selection still valid?

• The purpose of the OU1 remedy is to control and treat waters emanating from the Yak Tunnel. Numerical discharge limits are releva nt only for effluent quality. Therefore, a review of exposure assumptions, toxicity and other risk assessment-related issues is not
necessary.

• No new or changed ARARs have been identifi ed by the State of Colorado or EPA at the time of this Five Year Review that would affect treatment plant effluent standards.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• Mitigation of rising water levels caused by a suspected blockage in the Yak Tunnel through dewatering via the Black Cloud Mine sh ould be carefully monitored to determine effectiveness and minimize the potential for a sudden release of impounded water.

• Financial assurance for continued operation of the Yak Treatment Plant has not been established.

6.6 Issues

Based on the information collected during the Fi ve-Year Review, the following issues were identified:

Table 6-2 OU1 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy
1 Rising water levels in upper por tion of Yak Tunnel. No Potentially

2 Financial assurance for continued operation of the Yak Treatment Plant has not been established. No PotentiallyCalifornia Gulch Five-Year Report

Page 17 of 89 6.7 Recommendations and Follow-Up Actions

Table 6-3 OU1 Recommendations for Follow-Up Actions
Item No. Issue Recommendation for Follow-Up Party Responsible Due Date

1 Rising water levels in upper portion of Yak Tunnel. Monitor effectiveness of dewatering from Black Cloud Mine ASARCO, Resurrection. Res-ASARCO On-going

2 Financial assurance for continued operation of the Yak Treatment Plant has not been established. Establish financial assurance. Resurrection/EP A 12/07

6.8 Protectiveness Statement

The remedy is currently protective of human health and the environment. However, mitigation of rising water levels caused by a suspected blocka ge in the Yak Tunnel through dewatering via the Black Cloud Mine should be carefully m onitored to determine effectiveness.California Gulch Five-Year Report

Page 18 of 89 7.0 Operable Unit 2 - Malta Tailing Impoundment, Malta Gulch Tailing Impoundment and Lower Malta Gulch Fluvial Tailing

7.1 Description

Operable Unit 2 consists of three waste f eatures: Malta Tailing Impoundment, Malta Gulch Tailing Impoundment and Lower Ma lta Gulch Fluvial Tailing (Fi gure 7-1; Appendix A). Malta Tailing Impoundment consists of three sma ll impoundments occupying 4.6 acres and estimated contain approximately 10,000 cubic ya rds or waste. It was constr ucted by Leadville Silver & Gold for a pyrite recovery process mill that operated from 1983 to 1988.

Malta Gulch Tailing Impoundment is approximately 23 acres in size , located at the upper end of Malta Gulch, and contains an estimated total of 1,510,000 tons of waste. The first tailing impoundment was created by the Ore & Chemical Company (OCC) as part of a sink-float mill that operated from 1943 to 1946. After purchas e in 1968 by the Leadville Corporation, the property was leased from 1974 to 1987 to the H ecla Mining Company (know n as Hecla/Day). Hecla/Day used the site for disposal of silver ore tailing from the Sherman Mine, constructing four additional impoundments and two clarificati on ponds in the area of the original OCC tailing impoundment. Further, the Leadvi lle Corporation (or its precurso rs) operated a mill utilizing a cyanide leach process for silver extraction from the early 1970's until 1986. This operation disposed of approximately 50,000 tons of cyanide bearing tailing at the Malta Gulch site. On November 17, 2005 the Colorado Division of Reclam ation Mining and Safety (DRMS) initiated a bond forfeiture with the permitee, Leadville Co rporation, for the reclam ation of OU2 facilities operated under the permit.

Lower Malta Gulch is directly downstream of the Malta Gulch Tailing Impoundment. When OCC operated, the tailing impoundments were not entirely effective for containment, as approximately 600,000 tons of the tailing washed or flowed down Lower Malta Gulch. As a result, the Lower Malta Gulch Fluvial Tailing ar ea was created. The Lower Malta Gulch Fluvial Tailing area is approximately 26 acr es in size, consisting of fluvi al tailing deposits with an estimated volume of 30,000 cubic yards.California Gulch Five-Year Report

Page 19 of 89 Table 7-1 indicates the type s of contamination found in the different media on-site:

Table 7-1 Types of Contamination in Each Media for OU2

Media Contamination Shallow Tailing Elevated lead and zinc. Deeper Tailing Elevated lead and zinc are found in the Hecla an d Pre-Hecla tailing. Fluvial Tailing Elevated lead.

Table 7-2 lists the chronology of important events for Operable Unit 2 of the California Gulch site.

Table 7-2 Chronology of Site Events for OU2

Date Event 09/08/83 California Gulch placed on NPL

01/87 Phase I Remedial Investigation Report 09/91 Administrative Order on Consent for EE/CA at the Malta Gulch Tailing Impoundments 01/93 Partial Consent Decree with Hecla Mining Company to settle Hecla’s Site wide Liabilities 01/93 Partial Consent Decree with Leadville Silver and Gold Company to settle their Site wide Liabilities 08/93 EE/CA issued for Malta Gulch Tailing Impoundments 09/10/93 Action Memorandum issued for Removal Action at Malta Gulch Tailing Impoundments

08/14/95 Action Memorandum issued for Time Critical Removal Action at the Lower Malta Gulch Fluvial Tailing 09/05/95 Start date for Removal Action at Lower Malta Gulch Fluvial Tailing (8/14/95 Action Memorandum) 10/05/95 Start date for Removal Action at Malta Gulch Tailing Impoundment (9/10/93 Action Memorandum) 08/09/96 Action Memorandum issued for Time Critical Removal Action at Malta Tailing Impoundment 09/04/96 Start Date for Time Critical Removal Action at Malta Gulch Tailing Impoundment (8/9/96 Action Memorandum) 11/07/97 Discovery of drums at Leadville Mill 03/31/97 Completion of Removal Actions identified in Action Memorandum dated 9/10/93, 8/14/95, 8/9/96 04/15/98 Action Memorandum issued for Time Critical Removal Action of Leadville Mill drums 07/02/98 Time critical drum Removal Action completed 08/18/98 Final Pollution Reports on 9/10/93, 8/14/95, 8/9/96 Action Memorandum 09/30/99 Record of Decision 02/12/01 Intent to delete OU2 from the NPL

6/01 Deleted from NPLCalifornia Gulch Five-Year Report

Page 20 of 89 7.2 Response Actions

Response Action Selection/Implementation In September of 1991, EPA and Hecla Mining Cor poration signed an Administrative Order on Consent for the performance of an engineering evaluation/cost assessment (EE/CA) at the Malta Gulch Tailing Impoundments. The purpose of the EE/ CA was to determine the nature and extent of releases and to determine an appropriate response action.

EPA entered into agreements in January of 1993 with Hecla/Day, Leadville Corporation, and Leadville Silver & Gold to defi ne the extent of liability these companies would have in paying for cleanup at the Malta Gulch Tailing Impoundme nt and Malta Tailing Impoundment. Under a subsequent partial consent decree between U. S. EPA and Hecla/Day, $680,000 was set aside to perform cleanup at the site. An August 1994 Consen t Decree allowed the US, as the successor to OCC, to settle their liabilities at the Lower Malta Gulch Fluvial Tailing.

The remediation of OU2 occurred through four separate Removal Actions. In September 1999, the U.S. EPA issued a ROD for OU2 that determ ined that no further action was needed as a result of the four separate Removal Actions. These Removal Actions are summarized in Table 7-3.

Table 7-3 Response Actions for OU2

Area Action Memorandum Date Removal Action Taken Start Date Completion Date

Malta Gulch Tailing Impoundment 09/10/93 Grade and revegetate contiguous fluvial tailing.

Remove non-contiguous pockets of fluvial tailing and dispose of the material in the Malta Gulch Tailing Impoundment.

Provide for long term maintenance and monitoring. 10/05/95 03/17/97

Lower Malta Gulch Fluvial Tailing 08/14/95 Grade and revegetate contiguous fluvial tailing.

Remove non-contiguous pockets of fluvial tailing and dispose of the material in the Malta Gulch Tailing Impoundment.

Provide for long term maintenance and monitoring. 09/05/95 03/17/97

Malta Tailing Impoundment 08/09/96 Grade, compact, and revegetate the impoundments.

Dispose of pyritic materials from Apache Energy and Materials property.

Provide for long term maintenance and monitoring of the vegetated cap/cover. 09/04/96 03/31/97California Gulch Five-Year Report

Page 21 of 89 Table 7-3, cont’d Response Actions for OU2

Area Action Memorandum Date Removal Action Taken Start Date Completion Date

Leadville

Drums

04/15/98 Stage 42 drums in secure location.

Dispose or recycle oily liquids in accordance with Standards for the Management of Used Oil, 40 CFR 279.

Transport hazardous wastes to RCRAapproved treatment or disposal facility. 05/26/98 07/02/98

System Operation/Operation and Maintenance In addition to the four removal actions, the 1999 ROD specified the following monitoring requirements to maintain the effectiveness of the removal actions:

• Monitor vegetative cover.

• Inspect impoundments.

• Review zoning definition to ensu re consistency with the remedy.

• Review the status of the Colorado Division of Mining and Geology (DMG) permit and use of the mill and impoundments.

• Upon termination of the DMG permit, ensure that the final facil ity reclamation is protective of human health and the environment.

• Monitor groundwater in June of each year at nine locations for metals and other inorganic parameters.

7.3 Progress Since the Last Five Year Review

The last site-wide Five Year Review, which was finalized on September 29, 2001, indicated that all of the removal actio ns had occurred. In addition, Oper able Unit 2 was nominated by U.S. EPA for deleting as an NPL site on Februa ry 12, 2001 and deleted in June of 2001.

Activities since the last Five-Y ear Review include the preparation of two monitoring summary reports (2002 and 2004) limited to an assessment of vegetative cover a nd erosional features.

7.4 Five-Year Review Process

Document Review In preparing this Five-Year Review Repor t, the following documents were reviewed:

• Second Five-Year Review Report.

• OU2 2004 Monitoring Summary, California Gu lch Superfund Site Operable Unit 2 - Malta Gulch, Colorado Mountain College, March 2005.

• Site-Wide Groundwater Sampling, Summer 2005, California Gulch Superfund Site, Tetra Tech RMC, December 2005.California Gulch Five-Year Report

Page 22 of 89 Interviews were conducted with the following individuals to pr ovide supplemental technical information:

3⁄4 Doug Jamison – CDPHE 3⁄4 Mike Holmes – USEPA 3⁄4 Stan Christensen – USEPA 3⁄4 Rebecca Thomas - USEPA

Data Review Surface water quality data for the period 1995 through 2005.

Site Inspection The Site Inspection was performed on August 24, 2006 by the EPA Remedial Project Manager, Stan Christensen and Kenneth Napp, the HDR Project Manager. The assessment of Site conditions relied heavily on the recent observati ons of regulatory agency personnel interviewed during this Five-Year Review.

Based on the Site Inspection, conditions documented during the last Five-Year Review, discussions with regulatory agency personnel, and monitoring reports, all physical remediation elements in OU2 have been constructed and ar e in working order. Distressed vegetation was noted during the summer of 2004 (2004 Monitori ng Summary) and was again reported by EPA personnel in 2006.

7.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• The 2004 monitoring report identified numerous areas associated with sparse to no vegetation on the Malta Ta iling Impoundment. Minimal ve getation success and the presence of invasive plant species were identified associated with the Malta Gulch Tailing (HECLA facility ). EPA attributed this condition to a drought that had occurred during the summer of 2004. EPA personnel reported that areas of sparse or no vegetation remain in OU2.

• On November 17, 2005 the Colorado Divisi on of Reclamation Mining and Safety (DRMS) initiated a bond forfe iture with the permitee, Leadville Corporation for the reclamation of OU2 facilities operated under the permit. Once the DRMS completes final reclamation activities, EPA and CDPHE will assess the reclaimed facilities for unacceptable residual risks to human health or the environment. This will include the potential need for additional ICs to preven t disturbance of remediation/reclamation features under current zoning for industrial/mining uses.

• Procedures are in place for notification of EPA and CDPHE should a change in land use be approved by local governments.California Gulch Five-Year Report

Page 23 of 89 • Monitoring of vegetative cove rs appears to be occurring in accordance with the ROD requirements. The Site-Wide Groundwater Sampling Report (Summer 2005) identifies no exceedences of human health (primary) groundwat er standards for the nine monitoring in the vicinity of OU2, however, one well show ed a secondary and agricultural exceedence for one analyte.

• Based on document review, the Site Inspection and discussions with regulatory agency personnel, the remedy is functioning as intended by the decision documents.

Question B: Are the exposure assumptions, toxici ty data, and cleanup levels and RAOs used at the time of the remedy selection still valid?

• See Section 3.0 for a discussion of the Human Health and Risk Assessments.

• No new or changed ARARs have been identifi ed by the State of Colorado or EPA at the time of this Five Year Review that would apply to OU2.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• An Institutional Control Overlay (ICO) District was established to meet post-reclamation land use restriction requirements. However, the ICO District wa s repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedy.

• Settlement funds for operation and maintenance of the remedy are exhausted and the use Superfund resources is not feasible.

7.6 Issues

Based on the information collected during the Fi ve-Year Review, the following issues were identified:

Table 7-4 OU2 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy
1 Vegetative cover requires maintenance. No Yes

2 Additional ICs may be needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Potentially Potentially

3 Settlement funds have been exhausted and use of Superfund resources is not permitted. No PotentiallyCalifornia Gulch Five-Year Report

Page 24 of 89 7.7 Recommendations and Follow-Up Actions

Table 7-5 OU2 Recommendations for Follow-Up Actions
Item No. Issue Recommendation for Follow Up Party Responsible Due Date

1 Vegetative cover requires maintenance. Perform maintenance as required following the next scheduled annual inspection. Responsibility for O&M requires

clarification 12/07

2 Additional ICs may be needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Investigate the impacts of mine permit expiration on remedy protectiveness and develop/ implement ICs, as necessary. CDPHE 12/08

3 Settlement funds have been exhausted and use of Superfund resources is not permitted. Funding of operation and maintenance requires clarification EPA/CDPHE 12/08

7.8 Protectiveness Statement

The remedy is currently protective of human health and the environment. The absence of ICs to preclude disturbance of the remedy under current z oning has not impacted past or current protectiveness as the remedies were undisturbed at the time of this Five-Year Review. However, the potential exists for futu re impacts on remedy protectiveness if such an institutional control is not de veloped and implemented. EPA and CDPHE are informally notified by the County of any changes in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalized.California Gulch Five-Year Report

Page 25 of 89 8.0 Operable Unit 3 - Denver & Rio Grande Railroad (D&RG) Slag Piles/Railroad Easement/Railroad Yard

Operable Unit 3 (OU3) includes three slag piles (Arkansas Valley, La Plata, and Harrison St.) owned by the Denver & Rio Grande Western Rail road Company (D&RGW), an easement that runs diagonally through the City of Leadville, and a portion of the rail yard owned by D&RGW. Figure 8-1 (Appendix A) illustrate s the major features of OU3.

8.1 Description

Arkansas Valley The Arkansas Valley (AV) Slag Pile covers approxi mately 40 acres just west of Stringtown. The pile generally consists of slag produced by the AV Smelter that operated from 1882 to 1960. Based upon aerial photography, the pile volume in the late 1950s was approximately 1.2 million cubic yards, whereas in 1998 approximately 422,000 cubic yards of slag remained. The volume of stockpiled fine slag at the AV Smelter sl ag pile is approximately 190,000 cubic yards.

La Plata The La Plata Slag Pile, located west of the city limits of Leadville on Elm Street, has a volume estimated at 105,000 cubic yards

.

Harrison Street The Harrison Street Slag Pile was located near the northeast corner of Harrison Avenue and Elm Street, in a residential area. The original slag pile ranged from 20 to 50 feet in height and covered an area of approximately 3 acres. The Harri son Street Slag Pile was removed to original grade and relocated to the AV Slag Pile in March 1998.

Rail yard The rail yard, located between 12 th Street, Highway 24 and 17 th Street, has seen over 130 years of transportation activities, mostly associated with mining in the area. The portion of the rail yard formerly owned by D&RGW is located near th e north end of the town of Leadville and encompasses an area of roughly 43 acres and is cr ossed by abandoned rail lin es and access roads. Slag was used in the rail yard as ballast and as a road base to provide support for heavy vehicle traffic. Slag was also deposited around the lo ading dock due to spilla ge during transportation activities.

Rail Easement The rail easement includes the portion of railroad track that runs diagona lly through the town of Leadville and consists of approximately 25 feet on either side of the track centerline. Slag was used as a road base to provide support for hea vy vehicle traffic. Slag was also deposited as spillage from passing rail cars.California Gulch Five-Year Report

Page 26 of 89 Table 8-1 indicates the type s of contamination found in the different media on-site:

Table 8-1 Types of Contamination in Each Media for OU3

Media Contamination

Slag Elevated levels of zinc, lead, arsenic, and cadmium. Lo w acid-generating potential and a neutral to basic pH. Fine Slag (less than 3/8 of an inch) Elevated lead.

Table (8-2) lists the ch ronology of important events for OU3 of the California Gulch site.

Table 8-2 Chronology of Site Events for OU3

Date Event 09/08/83 California Gulch placed on NPL

1986 U.S. EPA’s contractor sampled the three slag piles as part of the California Gulch site Remedial Investigation 01/87 Phase I Remedial Investigation Report 1988 Soils Investigation conducted that included sampling of slag from the Harrison Street pile, La Plata pile, and an area west of Leadville (AV Smelter Slag Pile not included) 05/89 U.S. EPA conducted second sampling of slag to determine the concentrations of metals in three D&RGW slag piles and to evaluate potential of migration 12/03/91 Administrative Order on Consent with D&RGW for remedial investigation/feasibility study (RI/FS) of slag piles 1992 Remedial Investigation/Feasibility Study (RI/ FS) completed for seven major lead slag piles and a zinc slag pile 03/93 Site-Wide Screening Feasibility Study (SFS) completed 09/15/93 Administrative Order on Consent with D&RGW for completion of investigation and remediation activities 07/95 D&RGW submitted a ballast operations plan to U.S. EPA 08/95 Ballast operations commenced 05/96 D&RGW submitted a feasibility study for the stoc kpiled fine slag at the AV Smelter slag pile according to Consent Decree terms 05/06/98 Record of Decision signature for OU3 (only ad dress the fine slag stockpiled as a subpile of the Arkansas Valley Smelter Slag Pile 02/25/99 Request for Certification of Closure from Union Pacific Railroad Company 11/03/2000 Request for Partial Deletion of the Mineral Belt Trail from the State of Colorado to the U.S. EPACalifornia Gulch Five-Year Report

Page 27 of 89 8.2 Response Actions

Response Action Selection/Implementation

Arkansas Valley Slag Pile Only fine slag, a separate stockpile at the AV Slag Pile consisting of slag w ith a particle size of 3/8" or less, is addressed by the ROD. Based on consider ation of CERCLA requirements, detailed analyses of alternatives, and public co mments, U.S. EPA determined that a No Action alternative was the appropriate remedy. The No Action alternative leaves the stockpiled fine slag in its existing condition w ith no control or cleanup planne d. The selected remedy is protective of human health and the environment a nd is considered effective because no complete human or ecological exposure pathways were id entified for the stockpiled fine slag and the potential for release of metals in leachate from the stockpiled fine slag is minimal. The ROD also provides a contingency to us e the slag in the future if regi onal market demand exists for the material as a component in construction materials.

La Plata Slag Pile Based on the lack of fine slag or leachate generation, the ROD di d not require remedial action at this location.

Harrison Street Slag Pile As part of their ballast oper ations, D&RGW, approximately 104,000 cubic yards of slag were relocated to the AV Slag Pile in March 1998 to bring the Harrison Street Slag Pile to grade. As a result, soils were exposed contai ning elevated concentrations of lead. These soils create the potential for unacceptable human health risks shou ld the property be developed for residential use. To date, the land remains vacant.

Easement In work done under a Consent Decree with the D&RGW submitted a work plan proposing the easement to be converted into a segment of the Mineral Belt Bike Trail. The Mineral Belt Trail was completed in the late 1990's. Ownership of the easement was subsequently donated to Lake County via a quitclaim deed.

Rail yard During the summer and fall of 1997 D&RGW removed 1,264 cubic ya rds fine slag from the Rail yard and placed it onto the AV Slag Pile. As a result, soils were expos ed containing elevated concentrations of lead. These soils create th e potential for unacceptable human health risks should the property be developed for resident ial use. To date, the land remains vacant.

System Operation/ Operation and Maintenance

No system operation is required for the fine slag piles because the no action alternative was chosen. The1998 MOU entered into between Union Pacific, Lake County and US EPA indicated that the fine slag on th e easement would be incorporated into the Mineral Belt Trail and that Lake County is responsible for long term ma intenance on the Mineral Belt Trail. Slag has potential for resource utilization.California Gulch Five-Year Report

Page 28 of 89 However, any use of the slag would require it to be encapsulated for reuse. Encapsulation can include the use of fine slag in concrete or aspha lt aggregate, as a road base, or as backfill (so long as the slag is chemically bound or physical ly separated from an exposure by a barrier consisting of a different material).

8.3 Progress Since the Last Five Year Review

Activities related to OU3 since the last Five -Year Review finalized on September 29, 2001 was limited to maintenance of the Mineral Belt Trail.California Gulch Five-Year Report

Page 29 of 89 8.4 Five-Year Review Process

Document Review In preparing this Five-Year Review Repor t, the following documents were reviewed:

• Second Five-Year Review Report

Interviews were conducted with the following individuals to pr ovide supplemental technical information:

3⁄4 Doug Jamison – CDPHE 3⁄4 Mike Holmes – USEPA 3⁄4 Stan Christensen – USEPA 3⁄4 Rebecca Thomas - USEPA

Data Review Surface water quality data for the period 1995 through 2005.

Site Inspection The Site Inspection was performed on August 24, 2006 by the EPA Remedial Project Manager, Stan Christensen and Kenneth Napp, the HDR Project Manager. The assessment of Site conditions relied heavily on the recent observati ons of regulatory agency personnel interviewed during this Five-Year Review.

Based on the Site Inspection, c onditions documented during the last Five-Year Review and discussions with regulatory agency personnel, all physical remediation elements in OU3 have been constructed and are in working order.

8.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• The remedial goals of OU3 are being met for fine slag, as fine slag has been either been consolidated or capped.

• Remaining contaminated surface soils at the former Harrison Street slag pile will be capped should the land use change to residential. Procedures are in place for notification of EPA and CDPHE should a change in land use be approved by local governments.

• The Mineral Belt Trail is being mainta ined as required under the 1998 MOU.

• Based on document review, the Site Inspection and discussions with regulatory agency personnel, the remedy is functioning as intended by the decision documents.California Gulch Five-Year Report

Page 30 of 89 Question B: Are the exposure assumptions, toxici ty data, and cleanup levels and RAOs used at the time of the remedy selection still valid?

• See Section 3.0 for a discussion of th e Human Health Risk Assessments.

• No new or changed ARARs have been identifi ed by the State of Colorado or EPA at the time of this Five Year Review that would apply to OU3.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• No ICs exist (or were called for in the ROD) to ensure protection of human health in the event of changes in zoning. An Instituti onal Control Overlay (ICO) District was established to meet land use restriction requirements. Howe ver, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedy.

8.6 Issues

Based on the information collected during the Fi ve-Year Review, the following issues were identified:

Table 8-3 OU 3 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy

1 No ICs exist to ensure protection of human health in the event of changes in zoning. No Potentially

8.7 Recommendations and Follow-Up Actions

Table 8-4 OU3 Recommendations for Follow-Up Actions

Item No. Issue Recommendation for Follow Up Party Responsible Due Date

1 No ICs exist to ensure protection of human health in the event of changes in zoning. Prepare an ESD identifying appropriate ICs and implement the controls EPA 12/08California Gulch Five-Year Report

Page 31 of 89 8.8 Protectiveness Statement

The remedy is currently protective of human health and the environment. The absence of ICs to preclude disturbance of the remedy under current z oning has not impacted past or current protectiveness as the remedies were undisturbed at the time of this Five-Year Review. However, the potential exists for futu re impacts on remedy protectiveness if such an intuitional control is not deve loped and implemented. EPA and CDPHE are informally notified by the County of any changes in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalized.California Gulch Five-Year Report

Page 32 of 89 9.0 Operable Unit 4 - Upper California Gulch

9.1 Description

The Upper California Gulch site, OU4, is part of the Leadville mining district. Placer gold mining started with the discovery of gold in Ca lifornia Gulch in 1860. When the placer deposits were exhausted, underground mining was used to extract gold, silver, lead, and zinc ore. Breece Hill, above Upper California Gulch, was netw orked with underground mines, in an area approximately 8 square miles in size. As mine s were developed, waste rock was excavated and left near the mine entrances. Although a total of 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 scre ening. A map of OU4 is provided as Figure 9-1 (Appendix A).

The waste piles are identified in the Upper Calif ornia Gulch site by sub-ba sin: Garibaldi, Whites Gulch, Nugget Gulch, AY Minnie, Iron Hill, and Sout h Area (also includes Fluvial Tailing Site 4 known as Oro City). The twenty waste rock pile s in these sub-basins contain a total estimated volume of 431,000 cubic yards, impacting 28.3 acres. Waste rock piles are primarily weathered porphyry with limited to no vegetation, and with highly oxidized surfaces.

Fluvial tailing and fluvial tailing mixed with alluvial sediment s are located in the South Area and Fluvial Tailing Site 4, and are estimated at 102,000 cubic yards in volum e. The tailing are approximately 75 percent unvegetated with grasses and lodgepole pine in the remainder. There is also a wetland area along the Upper California Gulch channel within the site. Fluvial Tailing Site 4 (Oro City) is considered a cultural and historic resource for the Leadville mining district.

Flow in the Upper California Gu lch tributaries is primarily at tributable to spring runoff, generally occurring from early May to late summer , with a peak in early June. Flow can also occur as a result of summer thunde rstorms and other rain events.

The Upper California Gulch site is zoned for Industrial/Mining uses.California Gulch Five-Year Report

Page 33 of 89 Table 9-1 lists the chronology of important events for Upper California Gulch.

Table 9-1 Chronology of Site Events for OU4
Date Event 09/08/83 California Gulch placed on NPL

1986 Final Yak Tunnel/California Gulch Remedial Investigation 01/87 Phase II Remedial Investigation Report 8/94 Resurrection enters into a Consent Decree w ith the United States, the State of Colorado, and other PRPs to perform remediation work in OU4 07/95 EE/CA issued for Upper California Gulch 08/04/95 Action Memorandum issued for Removal Action at the Garibaldi Mine site 09/22/95 Start date for Removal Action at Garibaldi Mine site (08/04/95 Action Memorandum) 10/31/95 Action Memorandum issued for Time Critical Removal Action at a portion of Upper California Gulch 01/96 Completion of Removal Action at Garibaldi Mine site (08/04/95 Action Memorandum) 07/19/96 Action Memorandum issued for Removal Action at the Whites Gulch Sub-basin

08/28/96 Start date for Removal Action at the Whites Gulch Sub-basin, Agwalt Mine site (07/19/96 Action Memorandum) 10/03/96 Start date for Time Critical Removal Action at a portion of Upper California Gulch (10/31/95 Action Memorandum) 11/18/96 Action Memorandum amendment to July 19, 1996 memorandum. Amendment deletes the Removal Action at the Waste Rock Pile UCG-92A. 07/97 Completion of the Whites Gulch Sub-basin (Agwalt Mine) and a portion of Upper California Gulch (10/31/95 and 07/19/96 Action Memorandum) 01/15/98 U.S. EPA Proposed Plan 03/31/98 Record of Decision OU4 07/30/98 Final Pollution Reports on 08/04/95, 10/31/95, and 07/19/96 Action Memorandum 1998-2001 Remedial Action

02/03 Construction Completion Report 03/04 Explanation of Significant Differences deferring remedial action at Oro City to OU12

9.2 Response Actions

Response Action Selection/Implementation
In March, 1998, the U.S. EPA issued a ROD for OU4. Removal activities completed prior to the issuance of the ROD include the Garibaldi Sub- basin, the Agwalt Mine in Whites Gulch, and the Upper California Gulch Surface Water Diversion. The ROD identified additional response activities in Whites Gulch (Pri nter Girl Waste Pile), Nugge t Gulch Waste Rock, AY Minnie Waste Rock, Iron Hill Waste Rock, and Fluvial Tailing Site 4.

Fluvial Tailing Site 4, which is also known as Oro City, was not subject to any remediation because of concern regarding the historical si gnificance of the area as an early mining camp. U.S. EPA has deferred remediation activities at th is particular site until a determination can be made if the remaining areas of remedy specifi ed in the OU4 ROD are sufficient to meet any subsequent water quality standards established for the site. This assessment will be performed under OU12.California Gulch Five-Year Report

Page 34 of 89 The RAOs for OU4 are identified in the ROD as:

• Control erosion of contaminated ma terials into local water courses

• Control leaching and migration of metals from contaminated materials into the surface water

• Control leaching and migration of metals from contaminated materials into the groundwater

Specific response actions are summarized in Table 9-2.

Table 9-2 Response Actions at OU4

Area Removal Action Memorandum Date and

Action Action Taken Start Date Completion Date

Garibaldi Mine Sub-bas 8/4/95

Non- Time Critical Removal Action Construct portal flow and run-on collection system to capture portal flow and divert it around the waste rock pile

Construct riprap outlet structure

Construct ditch crossing

Construct two interceptor trenches to collect shallow alluvial flow and divert it around the waste rock pile 09/22/95 01/96

Upper California Gulch Surface Water Diversion 8/14/95

Time critical Removal Action Excavate diversion pond embankment to the invert of existing pipe outlets. Remove waste rock and tailing to Oregon Gulch Tailing Impoundment. Rebuild embankment and regrade diversion pond slopes.

Excavate and grade area upstream of diversion pond to increase pond water retention to 0.25 acre feet. Remove waste rock and tailing to Oregon Gulch Tailing Impoundment.

Construct diversion pond spillway to prevent overtopping of flows up to 50 cubic feet per second.

Construct reinforced concrete diversion pond outlet structure on west end of diversion pond.

Install rock filled High Density Polyethylene (HDPE) gabion check dam structures across the Upper California Gulch channel in three separate locations upstream of the diversion pond. 11/31/95 06/97California Gulch Five-Year Report

Page 35 of 89 Table 9-2, cont’d Response Actions at OU4

Area Removal Action Memorandum Date and

Action Action Taken Start Date Completion Date

Whites Gulch (Agwalt Mine Site) 7/19/96

Non-Time Critical Removal Action Collect and divert portal flow and runon away from the waste rock pile.

Regrade disturbed area to blend into surrounding terrain and revegetate using broadcast seeding at a rate of 30 pounds per acre 08/28/96 06/97

Nugget Gulch Remedial Action Consolidate waste rock piles Rubie (UCG-74), UCG-76, UCG-77, and North Mike (UCG-85) into Colorado Number 2 (UCG-71).

Regrade, cover, and revegetate Colorado Number 2 waste pile.

Construct run-on diversion ditches. 1998 2001

AY Minnie Waste Rock Pile Remedial Action Construct diversion ditches to reduce surface run-on and to reduce leaching and erosional releases.

Realign Lake County Road 2 to provide area for construction of sediment pond and further add protection from stability failures of timber cribbing without destroying mining heritage and cultural resources. 1998 2001

Iron Hill Remedial Action Regrade, cover and revegetate waste Rock Pile UCG-12. 1998 2001

Fluvial Tailing Site 4 and South Area Remedial Action Reconstruct Upper California Gulch stream channel and regrade selected fluvial tailing areas.

Revegetate south area channel.

The Oro City area in Fluvial Tailing Site 4 has not been addressed as specified in a March 2004 ESD. 2000.

Revegetation started in 2001.

Oro City activity is deferred 2001

System Operation/ Operation and Maintenance OU4 has the following monitoring requirements:

• Monitor vegetation cover and diversion channels.

• Inspection and repair/cleanout se diment ponds and other features.California Gulch Five-Year Report

Page 36 of 89 9.3 Progress Since the Last Five Year Review

Activities in OU4 since the last Five-Year Review were limited to maintenance and reporting in accordance with Final California Gu lch Superfund Site Operation and Maintenance Plan, Operable Units 4, 8 and 10 as revised in January 2005. Remedy elements identified in the previous Five-Year Review are limited to actions at Oro City which were subsequently deferred to OU12 under a March 2004 ESD.

9.4 Five-Year Review Process

Document Review In preparing this Five-Year Review Repor t, the following documents were reviewed:

• Second Five-Year Review Report

• OU4, OU8 and OU10 Fall 2005 Inspection Re port, Resurrection Mining Company

Interviews were conducted with the following individuals to pr ovide supplemental technical information:

3⁄4 Doug Jamison – CDPHE 3⁄4 Mike Holmes – USEPA 3⁄4 Stan Christensen – USEPA 3⁄4 Rebecca Thomas - USEPA

Data Review Surface water quality data for the period 1995 through 2005

Site Inspection The Site Inspection was performed on August 24, 2006 by the EPA Remedial Project Manager, Stan Christensen and Kenneth Napp, the HDR Project Mana ger. The assessment of Site conditions relied heavily on the recent observations of regulatory ag ency personnel interviewed during this Five-Year Review.

Based on the Site Inspection, c onditions documented during the last Five-Year Review and discussions with regulatory agency personnel, all physical remediation elements in OU4 have been constructed and are in working order.

9.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• The 2005 Inspection Report described minor amount of accumulated debris in constructed channels as well as minor amounts of erosi on. Based on this assessment, the remedy is functioning as intended by the design documents.California Gulch Five-Year Report

Page 37 of 89 • Procedures are in place for notification of EP A and CDPHE should a change in land use be approved by local governments.

• Based on document review, the Site Inspection and discussions with regulatory agency personnel, the remedy is largely functioni ng as intended by the decision documents. However, as discussed under Question C, belo w, the control of leaching and migration of metals from contaminated materials into the su rface water may not have been achieved to the degree originally intended.

Question B: Are the exposure assumptions toxicity data, and cleanup levels and RAOs used at the time of the remedy selection still valid?

• See Section 3.0 for a discussion of th e Human Health Risk Assessments.

• No new or changed ARARs have been identified by the State of Colorado or EPA at the time of this Five Year Review that would apply to OU4.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• RAO’s articulated in the ROD requiring, am ong other things, control of leaching and migration of metals from contaminated materi als into the surface water may not have been achieved to the degree originally intended. Th is issue will be addressed under OU12 as specified in the 1994 CD.

• No ICs exist (or were called for in the ROD) to ensure protection of human health in the event of changes in zoning or to prevent distur bance of engineered remedies as a result of development consistent with current zoning. An Institutional Control Overlay (ICO) District was established to meet post-response action land use restriction requirements. However, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedy.

9.6 Issues Based on the information collected during the Fi ve-Year Review, the following issues were identified:

Table 9-3 OU4 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy

1 Institutional controls are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. No YesCalifornia Gulch Five-Year Report

Page 38 of 89 9.7 Recommendations and Follow-Up Actions

Table 9-4 OU4 Recommendations for Follow-Up Actions

Item No. Issue Recommendation for Follow Up Party Responsible Due Date

1 Institutional controls are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Prepare an ESD identifying appropriate ICs and implement the controls. Resurrection EPA 12/08

9.8 Protectiveness Statement

The remedy is currently protective of human health and the environment. However, future remedial work may be required in order to attain final Site-wide water qua lity standards as determined pursuant to OU12. The absence of ICs to preclude disturbance of the remedy under current z oning has not impacted past or current protectiveness as the remedies were undisturbed at th e time of this Five-Year Review. However, the potential exists for future impacts on remedy protectiveness if such an intuitional control is not developed and implemented. EPA and CDPHE are informally notified by the County of any changes in zoning. Although this is not a form alized IC, it allows the remedy to be protective until an IC is formalized.California Gulch Five-Year Report

Page 39 of 89 10.0 Operable Unit 5 - Asarco Smelters/ Colorado Zinc-Lead Mill Site

10.1 Description

Remedial action at OU5 was approximately 50% co mplete at the time of the Five-Year Review. Therefore, the remedy was not subjected to the Five-Year Review process. A summary of the OU and the remedy status is provided below.

Operable Unit 5 (OU5) includes five smelter site s (Elgin Smelter, Grant/Union Smelter, Western Zinc Smelter, Arkansas Valley South Hillside Slag Pile collectively known as the EGWA sites), the Arkansas Valley Smelter and one mill site known as Colorado Zinc-Lead Mill (CZL). Maps of OU5 are provided as Figures 10-1 and 10-2 (Appendix A).

Prior to the remedial action smelter debris covere d the site consisting primarily of demolition debris such as brick, concrete, metal, tile, wood, and glass as well as residual mine waste and smelter materials including slag, coke/charcoal, limest one, ore, matte, tailing, and flue dust.

Table 10-1 lists the types of c ontamination found within OU5.

Table 10-1 Types of Contamination in Each Media
Media Contamination

Soils Arkansas Valley Smelter – Results of the Soil s Investigation indicate elevated arsenic, cadmium, lead, and zinc levels. Levels were highest from the samples taken from the bag-house area.

Colorado Zinc-Lead Mill – Elevated lead levels.

Elgin Smelter – Elevated lead and arsenic levels.

Grant/Union Smelter – Elevated lead and arsenic levels.

Western Zinc Smelter – Elevat ed lead and arsenic levels.

Arkansas Valley South Hillside Slag Pile – Elevated arsenic and lead levels.California Gulch Five-Year Report

Page 40 of 89 Table 10-2 summarizes the chronolo gy of important events in OU5.

Table 10-2 Chronology of Site Events for OU5

Date Event
09/08/83 California Gulch placed on NPL

01/87 Phase I Remedial Investigation Report 09/90 U.S. EPA and ASARCO entered into an Administrative Order on Consent for the performance of soils sampling and air monitoring. 1991 U.S. EPA issued a Unilateral Administrativ e Order requiring ASARCO to conduct studies and complete RIs. 1991 Smelter Site Reconnaissance 1991 Surface Water RI of the Ca lifornia Gulch site conducted 1991 through 1992 Hydrogeologic RI of the California Gulch site conducted

1993 Screening Feasibility Study conducted to initiate the overall CERCLA feasibility study process at the California Gulch site. 04/93 Smelter Remedial Investigation Report

08/94 ASARCO entered into a Consent Decree with the United States, State of Colorado, and other PRPs. ASARCO agreed to perform certain remediation work in OU5, OU7, and OU9.

1996 Final Surface Water RI Report

1996 Final Hydrogeologic RI Report

02/99 Focused Feasibility Study for Operable Un it 5, EGWA Sites submitted by ASARCO.

02/00 Focused Feasibility Study for Operable Unit 5 Arkansas Valley Smelter and Colorado ZincLead Mill Site submitted by ASARCO.

07/27/00 Proposed Plan describing U.S. EPA’s preferred alternative issued.

09/29/00 Record of Decision for AZ/CZL site of Operable Unit 5.

10/31/00 Record of Decision for EGWA site of Operable Unit 5.

Fall 2004 to

Present Remedial ActionCalifornia Gulch Five-Year Report

Page 41 of 89 10.2 Response Actions

Response Action Selection/Implementation

The ROD for the EGWA smelter sites was issu ed in October of 2000 and the AV/CZL ROD was issued in September of 2000. The remedy is summarized in Table 10-3:

Table 10-3 Response Actions for OU5

Area Remedy to be Implemented Start Date Completion Date Arkansas Valley Smelter/Colorado Zinc-Lead Mill Demolish smelter structures and excavate/transport flue dust to a lined repository.

Perform site grading to pr omote positive surface water drainage.

Consolidate tailing and non-residential soils located at the AV Smelter site and place an 18-inch thick soil cover. Construct run-on diversion ditches.

Establish ICs such as deed notices or deed restrictions to provide notification that a barrier is in place and to restrict land.

Provide services and cleanup consistent with the Lake County Community Health Program to one occupied residence.

Develop and implement an operation and maintenance program to include inspection and maintenance of the cover and surface water controls. 06/02 In Progress

Elgin Smelter/ Grant/Union Smelter/Western Zinc Smelter/ Arkansas Valley South Hillside Slag Pile Establish ICs to warn of potential hazards and to maintain the effectiveness of the remedy by limiting access to or use of the property.

Modify Lake County and/or City of Leadville zoning ordinances to create a zoning “overlay district” to provide a screening process to identify properties where special precautions or requ irements may be necessary and a mechanism to notify owners and/or developers of these requirements. The Gran t/Union, Western Zinc and Elgin Smelter sites will be included in the “overlay district.”

Develop and implement an operation and maintenance program for the “overlay district”. 10/31/00 In ProgressCalifornia Gulch Five-Year Report

Page 42 of 89 10.3 Progress Since Last Five Year Review

Progress since the last Five Year Review, whic h was finalized on September 29, 2001 includes the following:

• Completion of all Removal Actions

• Maintenance of the Removal Actions

• Release of the ROD

• Remedial design activities.

10.4 Protectiveness Statement

Remedial work at the Arkansas Valley Sme lter and Colorado Zinc-Lead Mill is incomplete. Therefore, the remedy is not yet protective alth ough overall protectivene ss is expected to be achieved once remedial construction is completed. The absence of ICs to preclude disturbance of the remedy under current z oning has not impacted past or current protectiveness as the remedy remains incomplete. However, the potential exists for future impacts on remedy protectiveness if such an intuitional control is not developed and implemented. EPA and CDPHE are informally no tified by the County of any changes in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalizedCalifornia Gulch Five-Year Report

Page 43 of 89 11.0 Operable Unit 6 - Starr Ditch/Penrose Dump/Stray Horse Gulch/Evans Gulch

11.1 Description

Remedial action at OU6 was incomplete at the time of the Five-Year Review. Therefore, the remedy was not subjected to the Five-Year Review pr ocess. However, unlike OU5, the remedy for OU6 largely consists of modifications to Res ponse Actions implemented under Action Memoranda. Therefore, the following discussion of OU6 include s an overall assessment of Response and (partial) Remedial Action effectiveness.

Operable Unit 6 consists of several consolidat ed mine waste piles (including Hamm’s Tailing Impoundment and the Penrose Mine Waste Pile); and approximately 2,200 acres of mining wastes in Stray Horse Gulch, the upper portion and headwa ter of Evans Gulch, and the lower portion of Evans Creek. On its western boundary, OU6 also in cludes some residential areas in the City of Leadville, and a drainage corridor along 5 th Street and Starr Ditch dow nstream of the confluence with the Stray Horse drainage. Figure 11-1 (Appendix A) illustra tes the major features of OU6.

The headwaters of Stray Horse Gulch are located eas t of Leadville in the area of Breece Hill and the Ibex/Irene Milling/Mining Complex. This water flows through Leadville via the 5 th Street drain and Starr Ditch and eventually discha rges to Lower California Gulch.

Hamm’s Tailing Impoundment covers an area of approximately 6.5 acres with a volume of approximately 245,000 cubic yards. The impoundment is located in Stray Horse Gulch.

The Penrose Mine Waste Pile was located south of East 4 th Street in Leadvill e and east of Hazel Street. Penrose Mine Waste Pile covered an area of about 4 acres and contained about 173,000 cubic yards of waste rock.

Historically, during heavy periods of precipitation or snow melt, ta iling materials from both Hamm’s and Penrose have been eroded and suspende d in surface waters moving downslope through residential areas of Leadville. This surface wate r is collected by Starr Ditch and is conveyed by the ditch to California Gulch and the Arkansas River. In addition, metals leached from the multiple other mine wastes present in OU6 and were tran sported to California Gulch via Star Ditch.

Current site uses for OU6 include recreation, commercial activities, mine tourism, and residential. The Leadville area has been classified as a Na tional Historic Landmark, and Little Stray Horse Gulch contains several famous historic mines, including the Matchless Mine of Baby Doe and Horace Tabor.California Gulch Five-Year Report

Page 44 of 89 Table 11-1 lists the types of contamination found at OU6.

Table 11-1 Types of Contamination in Each Media

Media Contamination Sediments Based on data from the EE/CA, elevated metals contamination was found in the sampling stations along Stray Horse Gulch. Tailing/Waste Rock Piles The Stray Horse Gulch tailing/waste rock piles we re analyzed by X-ray fluorescence for lead and arsenic concentrations as part of the Mi ne Waste Piles Remedial Investigation. Surface soils demonstrated elevated arsenic, lead, cadm ium, and zinc levels. Subsurface and foundation soils contained elevated to sign ificantly elevated arsenic, cadm ium, lead, and zinc levels.

Table 11-2 lists the chronology of important events for OU6 of the California Gulch site.

Table 11-2 Chronology of Site Events for OU6

Date Event 09/08/83 California Gulch placed on NPL

01/87 Phase I Remedial Investigation Report 11/06/95 Action Memorandum issued for Time Critical Removal Action at the Stray Horse Gulch Sediment Dam 05/01/96 Action Memorandum issued for Emergency Response Removal Action for the removal of sediments from the 5 th Street Drainage Ditch and Starr Ditch 07/26/96 Action Memorandum issued for Time Critical Removal Action at the Hamm’s Tailing Impoundment and the Penrose Mine Waste Pile 06/97 EE/CA for Stray Horse Gulch 06/24/97 Action Memorandum for Non-Time Critical Removal for Source Control Activities at Designated Mine Waste Piles 05/98 Addendum to EE/CA for Stray Horse Gulch 07/15/98 Action Memorandum for subsequent Non-Time Critical Removal Actions for Source Control at Designated Mine Waste Piles 08/19/98 Final Pollution Reports on 11/06/95, 05/01/96 Action Memorandums 10/26/98 Action Memorandum for a Non-Time Critical Removal Action for Water Management Activities at the Resurrection #1 Tailing Pile at the Upper End of Evans Gulch 05/99 Final Addendum No. 2 to EE/CA fro Stray Horse Gulch 06/02/99 Addendum to Action Memorandum for a Non-Time Critical Removal Action for Water Management Activities at the Resurrection #1 Tailing Pile at the Upper End of Evans Gulch (10/26/98) 06/02/99 Addendum to Action Memorandum for subsequent Non-Time Critical Removal Actions for Source Control at Designated Mine Waste Piles (07/15/98) 10/04/99 Final Pollution Report on 07/26/96 Action Memorandum for Time Critical Removal Action at the Hamm’s Tailing Impoundment and the Penrose Mine Waste Pile. 06/20/00 Action Memorandum for a Time Critical Removal Action in the Greenback - RAM Runoff Collection System 08/22/00 Amendment to Action Memorandum for a Time Critical Removal Action in the Greenback - RAM Runoff Collection System (06/20/00) 10/16/00 Final Pollution Report on 06/2/00 Action Memorandum 12/11/00 Final Phase I, II, III Removal Action Completion Report 6/25/01 Action Memorandum for Ibex/Irene waste pile

2002 Record of Decision 2005 Construction of an outlet structure on the Gaw Shaft under a Non-Time Critical Removal 2002-present Remedial Action (Removal of Ponsardi ne Waste Rock Pile, replacement of cribbing at Robert Emmett mine site, data collection to support design of bulkhead in LMDT)California Gulch Five-Year Report

Page 45 of 89 11.2 Response Actions

Response Action Selection/Implementation To date the following removal actions in OU6 as addressed in Action Memoranda have been completed:

Table 11-3 Response Actions for OU6

Area Action Memorandum Date and Action Removal Action Taken Start Date Completion Date

5 th Street, Starr Ditch, Harrison Slag Pile 1990 Removal Action Convert open ditches to covered culverts along both sides of 5 th Street.

Fence Starr Ditch from just north of 5 th Street to Monroe Street just east of the Harrison Street slag pile. 1990 1990

Stray Horse Gulch 11/06/95

Time Critical Removal Action Remove sediment from ditches and culverts around the Hamm’s Tailing Impoundment and from the 5th Street Drainage ditches and Starr Ditch

Construct a sediment control dam across the road from the east end of Hamm’s Tailing Impoundment in east Leadville. 08/24/95 08/30/95

5 th Street Drainage Ditch and Starr Ditch 05/01/96

Emergency Response Removal Action Remove sediment from the 5th Street Drainage Ditch from its headwall to and along Starr Ditch to its confluence with Lower California Gulch. 05/06/96 05/10/96

Hamm’s Tailing Impoundment and Penrose Mine Waste Pile 07/26/96

Time Critical Removal Action Transport the mine waste in the Penrose Mine Waste Pile to Hamm’s Tailing Impoundment

Revegetate the Penrose footprint and reshape the Hamm’s Tailing Impoundment to a more uniform and stable configuration.

If subsequent soil and/or air monitoring determines that adjacent residential properties have been impacted by this removal, soils which exceed 3,500 ppm of lead will be eligible for remediation under the Kids First Program. 07/26/96 09/30/98

Maid of Erin Wolftone Mine Adams Mill Mahala Mine Waste Piles 06/24/97 Phase I Non-Time Critical Removal Action Consolidate approximately 211,000 cubic yards waste from Maid of Erin Mine, Wolftone Mine, and the Mahala Mine Waste Piles. Place a liner system and rock cap over consolidated waste piles (3). 06/24/97 1998California Gulch Five-Year Report

Page 46 of 89 Table 11-3, cont’d Response Actions for OU6

Area Action Memorandum Date and Action Removal Action Taken Start Date Completion Date

Adelaide-Ward Mikados Highland Mary Pyrenees Waste Piles 07/15/98 Amendment to the 06/24/97 Action Memorandum (Phase II) Construct surface water run-on diversion channels around six mine waste rock piles.

Construct surface water run-off collection channels around four waste rock piles to capture and convey impacted water into retention basins.

Construct surface water retention basins.

Construct detention basins in lower Stray Horse Gulch to convey a 100 year storm event and to remain st able for a 500 year
storm event.

Rehabilitate Starr Ditch from 3rd Street to 5th Street to convey the 100-year, 24- hour storm event and to remain stable for a 500 year storm event.

Revegetate disturbed areas and the Hamm’s and Penrose piles. 1998 1999

Ponsardine Pile, RAM and Greenback, and Resurrection No. 1/Fortune Mine Waste Piles 06/02/99

Amendment to the 06/24/97 Action Memorandum (Phase III) Construct surface water run-on diversion channels around mine waste rock piles.

Construct surface water run-off collection channels around waste rock piles to capture and convey impacted water into retention basins.

Construct surface water retention basins.

. 1999 1999

Resurrection #1 Tailing Pile 10/26/98 06/02/99

Non-Time Critical Removal Action Install sediment control structure in the drainage basin downstream of the Resurrection #1 Tailing Pile. 06/08/98 1999California Gulch Five-Year Report

Page 47 of 89 Table 11-3, cont’d Response Actions for OU6

Area Action Memorandum Date and Action Removal Action Taken Start Date Completion Date

Greenback - RAM Runoff 06/20/00 08/22/00

Time Critical Removal Action (Phase IV) Identify suspected blockage in drainage system leading to the Greenback - RAM Collection System. Excavate blockages from drainage pathways or modify flow paths.

Install berm and drainage improvements from the Greenback collection system to direct the flow into a depression.

Advance a borehole and install a stand pipeto convey ARD discharged from abovedescribed collection systems to the Marion shaft adit for conveyance to the Leadville Mine Drainage Tunnel (LMDT) and ultimately the USBOR water treatment facility.

Transfer ponded water in the RAM collection system to the Greenback collection system to relieve the hydraulic pressure on the abandoned railroad grade.

Develop and implement a water quality monitoring plan. 06/30/00 10/13/00

Ibex/Irene Waste Rock Pile 6/25/01 Time Critical Removal Action Phase V Divert run-on around mine waste pile. Retain runoff in two impoundments to settle out sediments that could impact Parkville Reservoir. 6/25/01 Fall 2001

The OU6 ROD was released in 2003. The selected remedy consisted of the following elements:

• Maintenance of the existing Response Ac tions implemented prior to the ROD.

• Installation of a bul khead in the LMDT.

• Pumping ARD impounded behind the bulkhead to the surfac e with conveyance to the USBOR treatment plant via a gravity pipeline.

• Removal of the Ponsardine mine wa ste pile with on-Site disposal.

• Repair of unstable cribbing associated with the Robert Emmett mine site.

• Institutional Controls on future changes in land use.

Since the release of the ROD the followi ng remedy elements have been implemented:

• Maintenance of the existing response act ions implemented prior to the ROD

• Removal of the Ponsardine mine wa ste pile with on-Site disposal

• Repair of unstable cribbing associated with the Robert Emmett mine site.California Gulch Five-Year Report

Page 48 of 89 System Operation/ Operation and Maintenance An operation and maintenance plan will be prepar ed under the final remedy described in the 2003 ROD. To date, O/M consists of inspection of the surface water control features implemented prior to issuance of the ROD.

11.3 Progress Since the Last Five Year Review

Activities related to OU6 since the last Five-Year Review fina lized on September 29, 2001 included the following:

• Release of the ROD.

• Multiple tracer and other studi es to investigate the existe nce and quality of a hydraulic connection between the Marion ad it and the LMDT. These studies were performed to assess the effectiveness of the 2000 Removal Action th at diverted ARD discharged by surface water control structures to the subs urface for conveyance to the US BOR water treatment facility.

• Maintenance of the existing response act ions implemented prior to the ROD.

• Remedial design activities.

• Removal of the Ponsardine mine wa ste pile with on-Site disposal.

• Repair of unstable cribbing associated with the Robert Emmett mine site.

• Installation of monitoring wells in the LMDT as part of data collection to support remedial design.

• A Non-Time Critical Removal Action in 2005 to construct an engineered outlet for the Gaw Shaft. The Gaw Shaft is believed to be a relief point for the mine pool impounded behind suspected blockages in the LMDT.

• Negotiation with the USBOR for treatment of ARD to be extracted from behind the LMDT bulkhead once constructed. Negotiations are ongoing.

11.4 Five-Year Review Process

Document Review In preparing this Five-Year Review Repor t, the following documents were reviewed:

• Second Five-Year Review Report

• OU6 ROD

Interviews were conducted with the following individuals to pr ovide supplemental technical information:

3⁄4 Doug Jamison – CDPHE 3⁄4 Mike Holmes – USEPA 3⁄4 Stan Christensen – USEPA 3⁄4 Rebecca Thomas - USEPACalifornia Gulch Five-Year Report

Page 49 of 89 Data Review Surface and groundwater quality da ta for the period 1996 through 2005.

Site Inspection The Site Inspection was performed on August 24, 2006 by the EPA Remedial Project Manager, Stan Christensen and Kenneth Napp, the HDR Project Mana ger. The assessment of Site conditions relied heavily on the recent observations of regulatory ag ency personnel interviewed during this Five-Year Review.

Based on the Site Inspection, c onditions documented during the last Five-Year Review and discussions with regulatory agency personnel, al l physical response action elements required under Action Memoranda in OU6 have been constructed a nd are in working order. The Ponsardine mine waste pile has been removed and the unstable cribbi ng associated with the R obert Emmett mine site has been replaced. However, the major elements of the remedy described in the ROD have not been constructed nor have ICs been implemented.

Based on interviews with regulatory agency pers onnel. Several surface water management features require removal of accumulated sediment. These include:

• Culvert across the road from the Robert Emmett shaft.

• Ditches near Adelaide waste piles.

• A ditch at the Resurrection Fortune.

11.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• Surface water monitoring data indicate a large decline in metal loading emanating from Stray Horse Gulch since the completion of majo r Response Actions in 2000. Tracer studies confirm a hydraulic connection between the Ma rion adit and the LMDT indicating that ARD collected in OU6 and discharged to the subs urface is being treated at the USBOR water treatment facility. Regulatory agency pe rsonnel reported minor amount of accumulated debris in constructed cha nnels. Constructed caps on mine waste features are in good condition. Based on this assessment, the reme dy is functioning as intended by the Action Memoranda. The adequacy of observed reduction in metal loading to surface water will be formally assessed under OU12.

• Installation of a bulkhead in the LMDT with pumping of im pounded water as required under the ROD was intended to mitigate environmen tal and other risks associated with ARD currently impounded behind one or more susp ected blockages in the LMDT. Until the selected remedy is fully implemented, risks associated with this suspected “mine pool” remain. These risks include migration of ARD aw ay from the mine pool into mine workings, natural fractures/faults with pot ential discharge to alluvial groundwater and/or springs and seeps. There also remains some concern about a sudden release of AR D at the LMDTs portal should suspect blockage(s) in the LMDT fail.California Gulch Five-Year Report

Page 50 of 89 • Institutional controls to protec t engineered remedies and to identify properties where special precautions may be needed are included in the Selected remedy. Procedures are in place for notification of EPA and CDPHE should a ch ange in land use be approved by local governments.

• Given the remedy remains incomplete, it is no t fully functioning as intended by the decision documents.

Question B: Are the exposure assumptions toxicity data, and cleanup levels and RAOs used at the time of the remedy selection still valid?

• See Section 3.0 for a discussion of th e Human Health Risk Assessments.

• No new or changed ARARs have been identified by the State of Colorado or EPA at the time of this Five Year Review that would apply to OU6.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• None

11.6 Issues

Remedial action at OU6 was incomplete at the time of the Five-Year Review. Therefore, the remedy was not subjected to the Five-Year Review process. However, the remedy for OU6 largely consists of modifications to Response Actions implemen ted under Action Memoranda. Therefore, it was considered appropriate to identify the following issues related to selected remedy.

Table 11-4 OU6 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy
1 Delay in establishing control of the Mine Pool Potentially Potentially

11.7 Recommendations and Follow-Up Actions

Table 11-5 OU6 Recommendations for Follow-Up Actions
Item No. Issue Recommendation for Follow Up Party Responsible Due Date

1 Delay in establishing control of the Mine Pool Perform remedial action. EPA Reevaluate atnext fiveyear reviewCalifornia Gulch Five-Year Report

Page 51 of 89 11.8 Protectiveness Statement

The remedy is currently protective of human health and the environment. However, future remedial work may be required in order to attain final Site-wide water qua lity standards as determined pursuant to OU12. The absence of ICs to preclude disturbance of the remedy under current zoning and to identify properties where special precautions may be n ecessary has not impacted past or current protectiveness as the remedies were undisturbed at the time of this Five-Year Review. However, the potential exists for future impacts on remedy prot ectiveness if such an IC is not developed and implemented. The selected remedy will address the mine pool.California Gulch Five-Year Report

Page 52 of 89 12.0 Operable Unit 7 - Apache Tailing Impoundments

12.1 Description

Operable Unit 7 (OU7), the Apache Tailing Impound ments consisted of four distinct tailing impoundments located on the southern edge of Leadville adjacent to U.S. Highway 24. These impoundments were located in California Gulch, approximately 1,500 feet downstream from the Yak Tunnel Water Treatment Plant Surge Pond. A ma p illustrating the post-remedial Apache Tailing Impoundments is provided as Figure 12-1 (Appendix A).

Tailing placed in the Main Impoundment, and possi bly the North Impoundme nt, was generated by a mill known alternatively as the Venir Mill, the Ca lifornia Gulch Mill, and the ASARCO Leadville Milling unit, located on the hillside northeast of the Apache Tailings Impoundments. The available historical information indicates that this mill operated between 1939 and 1956, producing approximately 630,000 cubic yards of tailing in th e 11.3-acre Main Impoundment and an estimated 14,500 cubic yards of tailing in the 1.8-acre North Impoundment.

Apache Energy & Minerals Company operated the Apache Mill in the late 1970s and continued operations into the 1980s. The Apache Mill repr ocessed tailing from the Main Impoundment and deposited the remaining materials into Tailing Po nds No. 2 and No. 3, which were 1.5 and 0.5 acres in size, respectively, and located west and downs tream of the Main Impoundment. Tailing Ponds No. 2 and No. 3 were removed in 1997, as discussed below.

Table 12-1 presents the types of contaminati on present at the Apache Tailings Impoundments.

Table 12-1 Types of Contamination in Each Media

Media Contamination

Tailing Weathered sulfidic tailing on the surface of the North and Main Im poundments contains elevated lead and arsenic concentrations and has a high acid generating potential.

Dark gray sulfidic tailing occurs below the weathered sulfidic tailing on the North and Main Impoundments and contains elevated lead and arsenic concentrations.

Brown oxide tailing found only on the Main Impoundment contains elevated lead concentrations and arsenic concentrations lower than those found in sulfidic tailing. Brown oxide tailing has a significant neutralization potential counteracting acidic sulfidic tailing leachate.

Foundation soils found at both the Main and North Impoundments c ontain elevated lead concentrations and slightly elevated arsenic concentrations.California Gulch Five-Year Report

Page 53 of 89 Table 12-2 lists the chronology of important events for OU7.

Table 12-2 Chronology of Site Events for OU7
Date Event 09/08/83 California Gulch placed on NPL.

1986 Investigation study conducted by Colorado Department of Law. 1987 Investigation study conducted by US EPA. 01/87 Phase I Remedial Investigation Report. 1989 Investigation study conducted by US EPA.

09/90 U.S. EPA and PRPs entered into an Administrative Order on Consent (AOC) for the performance of soil sampling and air monitoring.

08/91 U.S. EPA issued a Unilateral Administrative Order (UAO) that required ASARCO to conduct studies and com p lete RIs. Fall 1991 Tailing remedial investigation performed.
1991-1992 Surface Water RI of the California Gulch site conducted.
Fall 1991- Winter 1992 Hydrogeologic RI of the California Gulch site conducted.

1993 Screening Feasibility Study conducted to initiate the overall CERCLA feasibility study process at the California Gulch site.

08/94 ASARCO entered into a Consent Decree with the Un ited States, State of Colorado, and other PRPs. ASARCO agreed to perform certain remediation work in OU5, OU7, and OU9. 01/94 Final Tailing Disposal Area Remedial Investigation Report. 08/95 Cultural Resources Investigations of the Apache Tailing Area Report. 01/96 Draft Apache Tailing Feasibility Study for OU7.

08/08/96 Action Memorandum issued for Removal (Response) Action at the Apache Energy & Minerals Property. 1996 Final Surface Water Remedial Investigation Report. 1996 Final Hydrogeologic Remedial Investigation Report.

04/07/97 Action Memorandum issued for Time-Critical Removal Action for Removal of Tailing Pond No. 2 and Tailing Pond No. 3 of the Apache Tailing Impoundment (Operable Unit 7).

1997 Field Investigation Data Report for the Apache Tailing Supplemental Remedial Investigation.

06/30/98 Final Pollution Reports for Time Critical Removal Actions at Tailing Ponds 2 & 3 of the Apache Tailin g Im p oundment

, 04/97 ; and A p ache Ener gy & Minerals Pro p ert y, 08/96.

01/00 Focused Feasibility Study, Apache Tailing Impoundments – Operable Unit 7 (OU7), California Gulch Superfund Site submitted by ASARCO. 01/25/00 Proposed Plan for U.S. EPA’s preferred alternative issued.

01/26/00 Action Memorandum issued for Time-Critical Removal Action fo r the Apache Tailing Impoundment ( O p erable Unit 7 )

. 06/06/00 Record of Decision. 12/17/03 Construction Completion ReportCalifornia Gulch Five-Year Report

Page 54 of 89 12.2 Response Actions

Response Action Selection/Implementation Multiple Removal Actions were conducted at OU7 between 1996 and 2000. On June 6, 2000, a ROD was signed and the selected remedy consiste d of the construction of a soil cover with a geosynthetic barrier and revegetati on followed by implementation of ICs and a long-term monitoring plan. The RAOs specified in the ROD for the Apache Tailing Impoundments are:

• Control airborne transpor t of tailing particles.

• Control erosion of tailing materials and deposition into local water courses.

• Control leaching and migration of metals fr om tailing into surface water and groundwater.

The removal and remediation activities performed at the Apache Tailing Impoundments are summarized in Table 12-3.

Table 12-3 Response Actions for Apac he Tailing Impoundments
Area Action Memorandum Date and

Action Removal Action Taken/Remedy to be Implemented Start Date Completion Date

Apache Energy & Minerals Property 08/08/96

Time Critical Removal Action Transport drums and bags of pyrite to the Malta Tailing Impoundment

Decontaminate and demolish the Apache Mill building and equipment 08/08/96 03/97

Tailing Pond Nos. 2 and 3 04/07/97

Time Critical Removal Action Remove Tailing Pond Nos. 2 and 3, berm material, and native soil and consolidate the material on the Main Impoundment

Pump surface water ponded on Tailing Pond Nos. 2 and 3 to Yak Water Treatment Plant prior to initiating excavation of tailing.

Divert potentially cont aminated surface run-off from the Main Impoundment to a sediment control structure.

Protect the toe of the Main Impoundment. 04/21/97 12/04/97California Gulch Five-Year Report

Page 55 of 89

Table 12-3 Response Actions for Apac he Tailing Impoundments
Area Action Memorandum Date and

Action Removal Action Taken/Remedy to be Implemented Start Date Completion Date

Main and North Impoundments 01/26/00

Time Critical Removal Action Regrade the material placed on the Main Impoundment during the removal of Tailing Pond Nos. 2 and 3.

Regrade the eastern embankment and the southwest embankment in the vicinity of the wooden box culvert on the Main Impoundment.

Excavate the tailing material overlying the claytile culvert at the southern edge of the Main Impoundment.

Place fill over a portion of the North Impoundment. 1/00 In Process

Main and North Impoundments Remedial Activity specified in the ROD Channelization of California Gulch through the southern portion of the main impoundment and construction of diversion ditches to control water run-on and run-off.

Regrade impoundments; place a multi-layer composite cover (including a geosynthetic barrier) over the tailing area, and revegetate.

Institutional controls will be put in place to warn of potential hazards and to limit access to the use of property . Modifications to city and/or county ordinances will involve the creation of a zoning overlay district to screen and identify properties where special precautions may be needed.

Long-term monitoring program to assess surface water and ground water quality. 6/01 12/03

System Operation/ Operation and Maintenance The previous Five-Year Review Report indicated that an Operat ion and Maintenance Program for the Main and North Impoundments of OU7 will be developed as the remedy is implemented. A formal O/M plan has not been prepared. However, the essential components of such a plan were presented in Final Focused Feasibility Study Re port for OU7. EPA reports that O/M currently consists of the following:

• Periodic inspection and maintenance of the so il cover and surface water control features.

• Annual monitoring of selected groun d water monitoring wells in OU7.California Gulch Five-Year Report

Page 56 of 89 12.3 Progress Since the Last Five Year-Review

Activities related to OU7 since the last Five-Year Review fina lized on September 29, 2001 included the following:

• Construction of the selected remedy

• Operation, maintenance, monitoring and reporting.

12.4 Five-Year Review Process

Document Review In preparing this Five-Year Review Repor t, the following documents were reviewed:

• Second Five-Year Review Report

• OU7 ROD

Interviews were conducted with the following individuals to pr ovide supplemental technical information:

3⁄4 Doug Jamison – CDPHE 3⁄4 Mike Holmes – USEPA 3⁄4 Stan Christensen – USEPA 3⁄4 Rebecca Thomas - USEPA

Data Review

• Surface and groundwater quality da ta for the period 1996 through 2005.

Site Inspection The Site Inspection was performed on August 24, 2006 by the EPA Remedial Project Manager, Stan Christensen and Kenneth Napp, the HDR Project Manager. The assessment of Site conditions relied heavily on the recent observations of re gulatory agency personnel interviewed during this Five-Year Review.

Based on the Site Inspection, c onditions documented during the last Five-Year Review and discussions with regulatory agency personnel, al l physical response action elements required under the ROD have been constructed and are in working order.

12.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• Based on document review, the Site Inspection and discussions with regulatory agency personnel, the remedy is functioning as intended by the decision documents.California Gulch Five-Year Report

Page 57 of 89 • Institutional controls are need ed to ensure protection of hu man health in the event of changes in zoning or to precl ude disturbance of engineered remedies as a result of development consistent with current zoning. Pr ocedures are in place for notification of EPA and CDPHE should a change in land us e be approved by local governments.

• Surface water quality data indicates that metal loading is decreasing in the vicinity of OU7. However, OU7 continues to contribute metal lo ad to California Gulch. This is indicated by surface water quality data for the period 1995 through 2005. This issue will be addressed under OU12 as specified in the 1994 CD

Question B: Are the exposure assumptions toxic ity data, and cleanup levels and RAOs used at the time of the remedy selection still valid ?

• See Section 3.0 for a discussion of th e Human Health Risk Assessments.

• No new or changed ARARs have been identifi ed by the State of Colorado or EPA at the time of this Five Year Review that would apply to OU7.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• An ICO District was established to meet post-response action land use restriction requirements. However, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding pr otectiveness of the remedy.

12.6 Issues Based on the information collected during the Fi ve-Year Review, the following issues were identified:

Table 12-4 OU7 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy

1 Institutional controls are needed to ensure protection of human health in the event of ch anges in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. No YesCalifornia Gulch Five-Year Report

Page 58 of 89 12.7 Recommendations and Follow-Up Actions

Table 12-5 OU7 Recommendations for Follow-Up Actions
Item No. Issue Recommendation for Follow Up Party Responsible Due Date

1 Institutional controls are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Develop and implement ICs. ASARCO 12/08

12.8 Protectiveness Statement

The remedy is currently protective of human health and the environment. However, future remedial work may be required in order to attain final Site-wide water qua lity standards as determined pursuant to OU12.

The absence of ICs to preclude disturbance of the remedy under current z oning has not impacted past or current protectiveness as the remedies were undisturbed at the time of this Five-Year Review. However, the potential exists for future impacts on remedy protectiveness if such an IC is not developed and implemented.California Gulch Five-Year Report

Page 59 of 89 13.0 Operable Unit 8 - Lower California Gulch

13.1 Description

Operable Unit 8 (OU8), identified as the 500 Year Flood Plain of Lower California Gulch, consists of the Colorado Zinc-Lead (CZL) Tailing Impound ment, the Fluvial Tai ling Impoundments (1,2, 3, 6, and 8), Gaw Waste Rock Pile, Non-resident ial Area Soils and Stream Sediments. A map identifying the features of Lower California Gu lch is presented as Figure 13-1 (Appendix A).

The area comprising Operable Unit 8 was originally a placer gold mining district starting with the discovery of gold in California Gulch in 1860. When the placer deposits began to become exhausted, underground mining was st arted to extract gold, silver, lead, and zinc ore. Ore was subsequently crushed and separated into metallic concentrates at nearby mills with mill tailing slurried into tailing impoundments. Fluvial deposits of ta iling occurred as tailing was released from impoundments. Waste rock from underground mining was frequently dumped near mine shafts, as was the case with the Gaw Waste Rock Pile.

The CZL site was an operating flotation mill that processed zinc-lead ores sporadically between 1925 and 1940. It is located approximately one mile west of Leadville and immediately north of Stringtown. The tailing impoundme nt at the site of the fl otation mill operation covered approximately 1.6 acres at an average depth of 7 feet. The tailing impoundment contained an estimated 17,000 cubic yards of tailing. Impoundme nt tailings contained a high concentration of pyrite. The foundation material be low the impoundment consisted of alluvium materials along with slag. The CZL tailing was removed to the Or egon Gulch Impoundment pursuant to a 1995 Removal action.

Fluvial Tailing Site 1 (FTS1) is adjacent to th e LaPlata Slag Pile and extends downstream in a westerly direction to a point approximately 1,000 feet upgradient of the CZL Tailing Impoundment. California Gulch flows through the tailing and th e gulch has cut a channel through the fluvial deposit. The fine to coarse grai ned tailing and alluvial/tailing ma terials range from 1-6 feet in depth. Alluvial sands, gravel, and cobbles lies be neath the tailing. The por tion of FTS1 that lies within OU8 comprises approximately 3.4 acres.

Fluvial Tailing Site 2 (FTS2) lies 200 feet downstream of FTS1 and is estimated to be 3.2 acres and contains a volume of 5,200 cubic yards (assuming an average depth of 1 foot). The fluvial tailing material in FTS2 is generally light brown to br own clayey silts and sands overlying light brown silt that contains cobbles and sand.

Fluvial Tailing Site 3 (FTS3) is located immediately downstream of Lake County Road 6 on California Gulch and covers approximately 4.8 acres . The flow of California Gulch through FTS3 is split into a north and south channel, with most of the flow occurring in the north channel.

Fluvial Tailing Site 6 (FTS6) is located on Ca lifornia Gulch between the Yak Tunnel Treatment Plant Surge Pond embankment and the Apache Ta iling Impoundments comprising approximately 4.2 acres. A portion of the Gaw waste rock pile also lies within FTS6.California Gulch Five-Year Report

Page 60 of 89 Fluvial Tailing Site 8 (FTS8) extends from the Ar kansas Valley Slag Pile to a point approximately 6,500 feet downstream of the confluen ce of California Gulch with the Arkansas River. FTS8 is a series of small discontinuous taili ng deposits with a total estimated area of 115 acres. However, the ROD only addresses the portion of FTS8 that lies within the 500-year flood plain. An estimated 45 acres of fluvial tailing are w ithin the floodplain boundaries.

The Gaw waste rock pile is located within FTS 6. The pile covers approximately one half acre and is estimated to have a volume of 7,500 cubic yards. The pile surr ounds the Gaw Shaft opening which has an outflow of approximately 0.1 cubic f eet per second. The Gaw shaft was subjected to a Non-Time Critical Response Ac tion under OU6 (See Section 12.0).

Table 13-1 presents the types of contamination located within OU8.

Table 13-1 Types of Contamination in Sites Within OU8

Media Contamination CZL Fluvial Tailing Impoundment Elevated concentrations of lead, cadmium, arsenic, and zinc with the potential to generate ARD Non Residential Soils Metals concentrations are ge nerally low and decrease with depth to the native undisturbed soils. Gaw Waste Rock Pile Surface soil contained lead at slightly elevated concentrations. Outflow from the Gaw shaft demonstrated neutral pH values, with minimally elevated sulfate concentrations. Metals typically were below limits of detection. FTS 1,2 and 3 Surface tailing had elevated levels of arsenic, cadmium, lead, and zinc. Subsurface tailing had elevated levels of arsenic, cadmium, and lead. Foundation soils had elevated levels of silver, cadmium, arsenic, lead, and zinc. FTS 6 Surface tailing had elevated levels of arse nic, cadmium, copper, l ead, mercury, silver, and zinc. Subsurface tailing had elevated levels of arsenic, cadmium, copper, lead, manganese, mercury, and zinc. Foundation soils had elevated levels of silv er, cadmium, copper, arsenic, lead, and zinc. The waste pile has potential for generating ARD. FTS 8 Surface tailing had elevated levels of ar senic, cadmium, copper, lead, and zinc. Subsurface tailing had elevated levels of arsenic, cadmium, lead, and zinc. Foundation soils had elevated levels of cadmium.

The Hydrologic Remedial Investigation conducted in 1996 indicted that only th e alluvial aquifer is contaminated. The upper 30 to 50-feet of the aquife r have elevated levels of arsenic, cadmium, copper, lead, zinc, and sulfates. Additional gr oundwater sampling during the Tailing RI in 1994 indicated elevated levels of ar senic, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, thallium, zinc, and sulfates. The metal concentrations and pH vary between all the sites in OU8.

The land surrounding and within OU8 is zoned for i ndustrial use by the City of Leadville and is currently not being used by any en tity. The area is mostly privat e property with no land held by Resurrection.California Gulch Five-Year Report

Page 61 of 89 Table 13-2 summarizes the chronolo gy of important events in OU8.

Table 13-2 Chronology of Site Events for OU8

Date Event 09/08/83 California Gulch placed on NPL

1986 Final Yak Tunnel/California Gulch Remedial Investigation 01/87 Phase II Remedial Investigation Report 09/90 U.S. EPA and PRPs enter into an Administrative Order on Consent for the performance of soil sampling and air monitoring in OU8 08/91 U.S. EPA issues a Unilateral Order on Cons ent that required ASA RCO to conduct studies and complete RIs 8/94 Resurrection enters into a Consent Decree w ith the United States, the State of Colorado, and other PRPs to perform remediation work in OU8 07/95 EE/CA issued for Lower California Gulch Colorado-Lead Zinc site 08/04/95 Action Memorandum issued for Removal action at the CZL Tailing Impoundment Site 09/04/95 Start date for Removal Action at CZL Tailing Impoundment Site (08/04/95 Action Memorandum) 01/96 Completion of Removal Action at CZL Tailing Impoundment Site (08/04/95 Action Memorandum) 06/11/98 Action Memorandum issued for Removal Action at Fluvial Tailing Sites 1, 2, 3, 6, and 8 06/30/98 Final Pollution Report on 08/04/95 Action Memorandum 08/28/96 Start date for Removal Action at the Fluvial Tailing Sites 1, 2, 3, 6, and 8 (06/11/98 Action Memorandum) 11/07/98 Completion of Removal Action at Fluvial Tailing Sites 1, 2, 3, 6, and 8 (06/11/98 Action Memorandum) 02/05/99 Final Pollution Report on 06/11/98 Action Memorandum

2000 U.S. EPA Final Focused Feasibility Study for the Lower California Gulch Operable Unit 8 09/29/00 Record of Decision for OU8 09/02/03 Construction Completion Report

13.2 Response Actions

Response Action Selection/Implementation

The remediation of OU8 was divided into seve n separate removal and response actions. In September, 2000, the U.S. EPA issued a Record of Decision (ROD) for OU8 to address the two completed Removal Actions and the five planned re mediation activities. The RAOs identified in the ROD include:

• Control airborne transport of tailing particles and contaminated non-residential soils.

• Control leaching and migration of metals from tailing, soil, waste rock, and contaminated fluvial and stream sediments into surface water.

• Control leaching and migration of metals from tailing, soil, waste rock, and contaminated fluvial and stream sediments into groundwater.

• Control erosion of tailing material and soil materials into local water courses.

• Control contaminant exposure to animals and aquatic life.California Gulch Five-Year Report

Page 62 of 89 The remedy elements are summarized in Table 13-3.

Table 13-3 Response Actions for OU8

Area Action Memorandum Date and Action Removal Action Taken/ Response Action to be Taken Start Date Completion Date CZL Tailing Impoundment 8/4/95

Non-Time Critical Removal Action Diversion and reclamation of a small portion of North California Gulch.

Remove of tailing, including one half acre in Fluvial Tailing Site 2 east of the CZL impoundment.

Relocation of tailing at the Oregon Gulch Impoundment.

Recontour and backfill former impoundment to promote drainage and revegetation. 09/0495 01/96

Fluvial Tailing and Stream Sediment 6/98

Interim Removal Action Remove approximately 5,800 cubic yards of fluvial tailing from poorly vegetated and erosion prone areas within FTS2, FTS3, FTS6, and FTS8. Fluvial tailing was removed to the Oregon Gulch Impoundment in OU10.

Remove approximately 1,350 cubic yards of sediment in conjunction with channel excavation. Sediment was removed to the Oregon Gulch Impoundment in OU10. 7/20/98 11/07/01

Non-Residential Soils Remedial Action Regrade to promote positive drainage.

Re-establish vegetation with soil amendments such as lime, nutrient, and organic matter as needed.

Institutional controls to include deed notices and restrictions, identify as an overlay district for zoning purposes. Not Available 9/2/03

Impounded Tailing Remedial Action No action is taken because the impounded tailing at the CZL Tailing Impoundment was removed pursuant to the 1995 interim removal action. N/A (No Further Action Remedy) N/A

Gaw Waste Rock Pile Tunnel Plug Remedial Action Take no action because the rock pile is not a source of metals contamination to surface or ground water N/A (No Action Remedy) N/ACalifornia Gulch Five-Year Report

Page 63 of 89 Table 13-3, cont’d Response Actions for OU8

Area Action Memorandum Date and Action Removal Action Taken/ Response Action to be Taken Start Date Completion Date Fluvial Tailing Sites 1, 2, 3, 6, 8 Remedial Action Regrade and re-establish vegetation with soil amendments such as lime, nutrient, and organic matter as needed.

Re-vegetate wetland areas with native wetland plant species.

Protect erosion prone areas along the gulch channel with riprap and a suitable filter fabric (approximately 2400 ft.).

Institutional controls to include deed notices and restrictions, identify as an overlay district for zoning purposes.

Maintenance and inspection of remediated

areas. Not Available 09/02/03

Stream Sediment Remedial Action - Excavate Fluvial Tailing at: - Removal Sites 2 and 3 in FTS2 - Removal Sites 4 and 5 in FTS3 - Removal Site 6 in FTS6 - Removal Sites 9-1 through 9-7, 10, 8- 1 through 8-5

Remove sediment from Fluvial Site 11 and reconstruction of California Gulch in geomorphically unstable, braided channel areas of FTS3 to divert flow to south channel.

Construct channel through FTS6 to convey 500 year flood plain.

Remove sediment and construct channel improvements in erosion prone areas.

Excavate sediment to clear channel at Removal Site 12 in FTS 2. Not Available 09/02/03California Gulch Five-Year Report

Page 64 of 89 System Operation/ Operation and Maintenance

The following monitoring requirements are im posed under the Final California Gulch Superfund Site Operation and Maintenance Plan , Operable Units 4, 8 and 10 as revised in January 2005.

• Biannual inspection/maintenance of vege tation cover and diversion channels.

• Institutional controls as discussed in the ROD.

13.3 Progress Since the Last Five Year Review

The last site-wide Five Year Review, which was finalized on September 29, 2001, indicated that no removal actions had been completed. Since the last review, all remedial action has been completed. Biannual inspecti ons are performed in accordance with the Final California Gulch Superfund Site Operat ion and Maintenance Plan, Operable Units 4, 8 and 10 as revised in January 2005.

13.4 Five-Year Review Process

Document Review In preparing this Five-Year Review Repor t, the following documents were reviewed:

• Second Five-Year Review Report

• OU4, OU8 and OU10 Fall 2005 Inspection Report, Resurrection Mining Company

Interviews were conducted with the followi ng individuals to provide supplemental technical information:

3⁄4 Doug Jamison – CDPHE 3⁄4 Mike Holmes – USEPA 3⁄4 Stan Christensen – USEPA 3⁄4 Rebecca Thomas - USEPA

Data Review

• Surface and groundwater quality da ta for the period 1996 through 2005.

Site Inspection The Site Inspection was performed on A ugust 24, 2006 by the EPA Remedial Project The Site Inspection was performed on August 24, 2006 by the EPA Remedial Project Manager, Stan Christensen and Kenneth Napp, the HDR Project Manager. The assessment of Site conditions relied heavily on the recent observations of regulatory agency personnel interviewed dur ing this Five-Year Review.California Gulch Five-Year Report

Page 65 of 89 Based on the Site Inspection, conditions documented during the last Five-Year Review and discussions with regulatory agency personnel, most physical response action elements required under the ROD in OU8 ha ve been constructed and are in working order. However, vegetative cover in a por tion of FTS 2 proximal to OU5 was limited (See Photo No. 1 – Appendix C). In addi tion, water ponded on the tailing deposit exhibited coloration in dicative of ARD. Ponded water a ppeared to be discharging to California Gulch. In addition, the California Gulch channel flowed through the tailing deposit.

13.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• The 2005 Inspection Report identified areas of limited vegetation at FTS-1 and Non-Residential Soils Areas and recomme nded additional seed and fertilizer. No documentation exists indicating whethe r maintenance had been performed.

• Based on document review, the Site Inspect ion and discussions with regulatory agency personnel, the remedy is largely functioning as intended by the decision documents. However, the condition of FT S-2 suggests that the tailings are vulnerable to erosion and remain a sour ce for metal loading to California Gulch. Recent surface water monitoring data (2003 through 2005) suggests that an unacceptable level of metal lo ading occurs in the vicinity of FTS-2 in the spring, during the period when the Arkansas River is most sensitive to metal loads. Therefore, the affected portion of the FTS-2 remedy requires repair or replacement in order to meet the in tent of the decision documents. EPA recognizes that limited spatial data de nsity precludes a definitive estimate of metal loading from FTS-2. In addition, so me of the distresse d areas (with ponded ARD) lie within the boundaries of OU5 where the remedy remains under construction.

• Institutional controls are n eeded to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Pro cedures are in place for notification of EPA and CDPHE should a ch ange in land use be approved by local governments.

Question B: Are the exposure assumptions toxicity data, and cleanup levels and RAOs used at the time of the remedy selection still valid?

• See Section 3.0 for a discussion of th e Human Health Risk Assessments.

• No new or changed ARARs have been iden tified by the State of Colorado or EPA at the time of this Five Year Re view that would apply to OU8.California Gulch Five-Year Report

Page 66 of 89 Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• An ICO District was established to meet post-response action land use restriction requirements. However, the ICO Distri ct was repealed by Lake County in 2006. As a result, concerns remain rega rding protectivene ss of the remedy.

13.6 Issues Based on the information collected during th e Five-Year Review, the following issues were identified:

Table 13-4 OU8 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy

1 A portion of Non-Residential Soils Areas, Fluvial Tailing Site (FTS) No. 1 and FTS-2 remedies in need of repair or replacement. Yes Yes

2 Institutional controls are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. No Yes

13.7 Recommendations and Follow-Up Actions

Table 13-5 OU8 Recommendations for Follow-Up Actions

Item No. Issue Recommendation for Follow Up Party Responsible Due Date

1 A portion of Non-Residential Soils Areas, Fluvial Tailing Site (FTS) No. 1 and FTS-2 remedies in need of repair or replacement. Modify/repair the existing remedy so that mine waste does not come into contact with California Gulch flows or allow precipitation to pond on the tailing surface. Resurrection 12/07

2 Institutional controls are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Develop and implement IC. Resurrection 12/08California Gulch Five-Year Report

Page 67 of 89 13.8 Protectiveness Statement

Although the remedy is currently considered to be protectiv e of human health and the environment, the poor condition of FTS-2 remedy requires repair or replacement in order to meet the intent of the decision documents . In addition, future remedial work may be required in order to attain final Site-wide wa ter quality standards as determined pursuant to OU12. The absence of ICs to preclude disturban ce of the remedy under cu rrent zoning has not impacted past or current prot ectiveness as the re medies were undisturbed at the time of this Five-Year Review. However, the potenti al exists for future impacts on remedy protectiveness if such an IC is not developed and implemented. EPA and CDPHE are informally notified by the County of any changes in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalized.California Gulch Five-Year Report

Page 68 of 89 14.0 Operable Unit 9 - Populated Residential Areas

14.1 Description

Operable Unit 9 (OU9), Residential Populated Areas, includes those portions of the Site where the land use is residentia l or that are currently zoned as residential/populated areas and as low-density residential areas (Figure 3-1) (Appendix A). These include residential yards, vacant lots, parks, school yards, playgrounds, and community use areas, including unpaved streets and alleys. Operable Unit 9 a ddresses concentrations of lead in soil, mine wastes (38 mine waste piles located within the populated areas of eastern Leadville), dust, paint, and water that exceed a specific set of trigger criteria.

Table 14-1 summarizes the chronolo gy of important events in OU9.

Table 14-1 Chronology of Site Events for OU9

Date Event 09/08/83 California Gulch placed on NPL.

1986 Investigation study conducted by Colorado Department of Law. 5/86 Emergency response at a private well 01/87 Phase I Remedial Investigation Report. 09/28/90 U.S. EPA and settling defendants entered into an Administrative Order on Consent (AOC) for the performance of soils sampling and air monitoring. 08/29/91 U.S. EPA issued a Unilateral Administrative Order (UAO) that required ASARCO to conduct studies and complete RIs related to Demographics Work Plan; Final Sampling Plan for Sampling and Analysis of Lead Occurrence With in and Immediately Adjacent to Residences; Soil Investigation Work Plan; Mine Waste Pile Remedial Investigations; and other issues. 09/10/91 U.S. EPA issued a UAO that required Resurrection Mining Company to conduct and complete the final Soils Investigation Work Plan. 09/24/92 U.S. EPA entered into an AOC with ASARCO and Resurrection Mining Company for performance of a metals speciation program. 09/04/93 Partial Consent Decree among the United Stat es, State of Colorado, and settling defendants settling the U.S. and State’s claim for past resp onse costs incurred prior to February 1, 1991 and February 1, 1992. 07/15/94 Final RI pursuant to the UAO dated 09/10/91 submitted by Resurrection Mining Company.

8/94 Consent Decree with ASARCO and Resurrection Mining Company to define areas of responsibility for the two companies and the U.S. government and to develop the Kids First Work Group. 09/94 Metals Speciation Data Report submitted. 11/94 Engineering Evaluation/Cost Analysis work plan prepared to evaluate lead concentrations in soils within parks and playground areas in OU9. 5/25/95 Initiation of LCHP/ASARCO Outr each Program for Kids First Program 10/16/95 Action Memorandum issued for time critical removal action for two residences, Kids First Program, in Operable Unit 9. 12/95 Draft Mine Waste Engineering Evaluation/Cost Analysis, California Gulch Superfund Site, Leadville, Colorado. 1996 4 Action Memoranda issued for time critical re moval actions at five separate residences, Kids First Program, in Operable Unit 9.California Gulch Five-Year Report

Page 69 of 89 Table 14-1 Chronology of Site Events for OU9
Date Event
1/96 Human Health Risk Assessment issued 07/23/96 Responses to Comments #2, Mine Waste Engineering Evaluation/Cost Analysis from ASARCO. 1997 15 Action Memoranda issued for time critical re moval actions at 15 separate residences, Kids First Program, in Operable Unit 9. 05/26/98 Final Pollution Report for 20 time critical removal actions performed under the Kids First Program, Operable Unit 9 during the time period starting July 31, 1996 through October 30, 1997. 1998 18 Action Memoranda issued for time critical re moval actions at 18 separate residences, Kids First Program, in Operable Unit 9. 07/01/98 Action Memorandum Amendment for time critical removal action for PRP financed removal actions addressing mine waste rock piles located in the residential populated areas in Operable Unit 9 dated August 15, 1996. 12/15/98 Final Pollution Report for 20 time critical removal actions performed under the Kids First Program in Operable Unit 9 during the time period starting October 31, 1997 through November 6, 1998. 1999 9 Action Memoranda issued for time critical removal actions at 9 separate residences, Kids First Program, in Operable Unit 9. am, in Operable Unit 9. 09/02/99 Record of Decision, Residential Populated Areas, Operable Unit 9, California Gulch Superfund Site, Leadville, Colorado. 10/12/99 Final Pollution Report for three time critical removal actions performed under the Kids First Program in Operable Unit 9 during the time period starting June 22, 1999 through September 30, 1999. 10/28/99 Final Pollution Report for three time critical removal actions performed under the Kids First Program in Operable Unit 9 during the time period starting August 23, 1999 through September 30, 1999. 12/01/99 Final Pollution Report for four time critical removal actions performed under the Kids First Program in Operable Unit 9 during the time period starting September 13, 1999 through November 1, 1999. 2000 Two Action Memoranda for time critical rem oval actions at the 2 residences , Kids First Program, in Operable Unit 9. 6/1/00 LCCHP was initiated to take the place of the interim Kids First Program 11/03/00 Petition for a partial deletion of portions of Operable Unit 9. 1/01 Remedial Design for Lake County Community Health Program (LCCHP) 02/28/01 Leadville Kids First Program Report, 1994-1999 Progress and Results issued. 07/31/01 Waste Rock Pile completion report issued

05/02 LCCHP Guidelines established. 2006 OU9 Performance standards were metCalifornia Gulch Five-Year Report

Page 70 of 89 14.2 Response Actions

Response Action Selection/Implementation

The remediation of OU9 was divided into numer ous separate Removal Actions as well as remedial actions. Table 14- 2 summarizes these actions:

Table 14-2 Response Actions for OU9

Area Action Memorandum Date and Action Removal Action Taken/Remedy to be Implemented Start Date Completion Date

Private Well N/A Water connection to the Parkville Water District was provided 5/86 5/29/86

Kids First Program - individual residences 10/16/95 - 04/21/00

Time Critical Removal Actions Addressed contaminated media associated with residential properties 10/16/95

- 04/21/00 Various

Waste Rock Piles 08/15/96

Time Critical Removal Actions Addressed elevated levels of contaminants in mine waste rock piles 08/15/96 7/31/01

Morning Star Day Care Fall 2005

Time Critical Removal Action Addressed contaminated media associated with residential properties Fall 2005 Fall 2005

LCCHP Multiple Residences 2000 through mid-2005

Remedial Action Addressed contaminated media associated with residential properties 2000 In Progress

Removal actions under the Kids First Program started on October 16, 1995 as described in the Consent Decree dated August 2 5, 1994 between U.S. EPA, ASARCO, and Resurrection Mining Company. The Lake C ounty Community Health Program (LCCHP) described in the ROD was intended to take the place of the Ki ds First Program.California Gulch Five-Year Report

Page 71 of 89 The ROD, signed on September 2, 1999, describes RAOs for OU9 and the selected remedy; the LCCHP. RAOs for OU9 include:

• RAO-1. No more than 5% of childre n age 0-72 months residing within OU9, either now or in the future, should have blood lead values exceeding 10 micrograms per deciliter (ug/dl).

• RAO-2. No more than 1% of childre n age 0-72 months residing within OU9, either now or in the future, should have blood lead values exceeding 15 ug/dl.

• RAO-3 Reduce direct exposure of lead incurred by children which result in optimal risk reduction through effective use of resources.

This remedy involves an extensive education and intervention program to manage lead exposure at the site. The education program focuses on raising public awareness about risks from lead and encourages participat ion in the LCCHP. Through this program, Leadville residents may request an investigation of lead leve ls in soil dust, paint, and water on their property. The LCCHP also in cludes voluntary blood lead monitoring (with financial incentives, as appropriate) for all ch ildren between the ages of 6 and 72 months and pregnant or nursing women.

If the concentration of lead in blood of a child or a pre gnant or nursing woman exceeds the blood lead criterion, or if the concentration of lead exc eeds a specified set of trigger criteria for one or more of the environmen tal media at a residence, then appropriate actions will be taken to address the exceeden ce. The trigger levels are summarized in Table 14-3.

Table 14-3 Trigger Levels for Lead

Media Lead Concentration
Soils 3,500 mg/Kg Mine Waste Piles 3,500 mg/Kg Interior/Exterior Paint Greater than 1 mg/cm 2 triggers educational actions Greater than 6 mg/cm 2 triggers active remediation. Dust Greater than or equal to 2,000 ppm triggers active remediation. Tap Water Greater than or equal to 15 μ g/L triggers active remediation. Blood Lead No more than 5% of children age 0-72 months residing within OU9, either now or in the future, should have blood lead values exceeding 10 micrograms per deciliter (ug/dl). No more than 1% of children age 0-72 months residing within OU9, either now or in the future, should have blood lead values exceeding 15 ug/dl.California Gulch Five-Year Report

Page 72 of 89 When one or more of the trigger criteria ar e exceeded, a work group evaluates a range of different response actions. The most appr opriate response action is determined by evaluating the nature and extent of the ex ceedence, overall protectiv eness of the action, compliance with applicable or relevant and appropriate requirements, long-term effectiveness and permanence, short-term effectiveness, implementability, cost effectiveness, and community impacts. The work group also considers the views of the property owner and no response action will be implemented without permission of the property owner. Extensive education and inte rvention program to manage lead exposure at the site is an integral co mponent of each action considered.

The selected remedy also includes ICs to ensu re the effectiveness of the LCCHP. These ICs were to include the creation of an ove rlay district to provide notification and information regarding the LCCHP and a da ta management and tracking system to maintain sampling, response action, and ot her information related to individual properties.

System Operation and Maintenance The LCCHP and associated reporting consti tute operation and maintenance of the remedy.

14.3 Progress Since the Last Five-Year Review

The LCCHP was implemented as required by the ROD and under the Methods and Standards for Evaluating the Performance of the Program (LCCH P Annual Report, 2005). ASARCO continued to implement the LCCHP until July 2005 after which EPA implemented the LCCHP. Performance standa rds were met in March 2006. In the spring of 2006, EPA offered an opportunity to par ticipate in the Lake County Community Health Program to property owners once it was determined that performance standards had been met. EPA continues to negotiate with Stakeholders towards adoption of the LCCHP as a formal IC for OU9 (residential soils).

14.4 Five-Year Review Process

Document Review

• Second Five-Year Review Report

• OU9 ROD

• Methods and Standards For Evaluating The Performance Of The Lake County Community Health Program (LLCHP), LCCHP Performance Standards Working Group, May 2002.

• 2005 LCCHP Annual Report

• Final Lake County Community Health Pr ogram, 2005 Annual Report, MFG, Inc., April 2006.

Data Review

NoneCalifornia Gulch Five-Year Report

Page 73 of 89 Site Inspection Operable Unit 9 was not subjected to a formal Site Inspection give n the numerous smallscale and diverse remedial actions as well as the adequacy of operation and monitoring documentation.

14.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• Performance standards for OU9 were me t in March 2006. Therefore, the remedy is largely functioning as inte nded by the decision documents.

• An ICO District was established to satis fy ROD required ICs. However, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the reme dy. EPA continues to negotiate with Stakeholders towards adoption of the LCCHP as a formal IC for OU9 (residential soils).

• Isolated areas of soils in outlying poti ons of OU9 were identified as containing arsenic at levels that ex ceed the upper range of plausible action levels for residential land use. The arsenic exc eedences occurred where the corresponding lead concentration was below the residential action level. Therefore, it is possible that unacceptable exposure of sensitive populations might occur should these areas be developed.

• No Operation and Maintenance Plan is in place for remediated properties in OU9.

Question B: Are the exposure assumptions toxicity data, and cleanup levels and RAOs used at the time of the re medy selection still valid?

• Performance standards established by EP A for OU9 (Populated Areas) were met in March, 2006. This conclusion was base d on an evaluation of the Program in accordance with the established performa nce standards expressed as goals for blood lead levels in childre n. Given that these objectives have been met, it is reasonable to conclude that remediation goals for lead described above remain protective of human health. The exposure assumptions and toxicity data used to develop range of plausible action levels for arsenic, published in the Human Heath Risk Assessment (Part B), remain valid.

• No new or changed ARARs have been iden tified by the State of Colorado or EPA at the time of this Five-Year Review that apply to OU9.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• NoCalifornia Gulch Five-Year Report

Page 74 of 89 14.6 Issues

Based on the information collected during th e Five-Year Review, the following issues were identified:

Table 14-4 OU9 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness of Remedy

1 An ICO District was established to satisfy ROD required ICs. However, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedy. Yes Yes

2 Isolated areas of soils in outlying potions of OU9 were identified as containing arsenic at levels that exceed the upper range of plausible action levels for residential land use. The arsenic exceedences occurred wh ere the corresponding lead concentration was below the residential action level. Therefore, it is possible that unacceptable exposure of sensitive populations might occur should these areas be developed. No Potentially

3 No O&M Plan exists for remediated properties Yes YesCalifornia Gulch Five-Year Report

Page 75 of 89 14.7 Recommendations and Follow-Up Actions

Table 14-5 OU9 Recommendations for Follow-Up Actions

Item No. Issue Recommendation for Follow Up Party Responsible Due Date

1 An ICO District was established to satisfy ROD required ICs. However, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedy. Formalize IC EPA/Lake County 12/08

2 Isolated areas of soils in outlying potions of OU9 were identified as containing arsenic at levels that exceed the upper range of plausible action levels for residential land use. The arsenic exceedences occurred where the corresponding lead concentration was below the residential action level. Therefore, it is possible that unacc eptable exposure of sensitive populations might occur should these areas be developed. Consider creation of an IC to address areas of elevated arsenic in soils where development may result in unacceptable exposure of sensitive populations EPA/Lake County 12/08

No O&M Plan exists for remediated properties Prepare and implement an O&M Plan EPA/Lake County 12/08

14.8 Protectiveness Statement

The remedy is protective of huma n health and the environment.

Performance standards for OU9 were met in March 2006 as a result of the LCCHP. Given that hazardous substances remain w ithin OU9, operation and maintenance of the LCCHP is necessary to ensure the protectiveness of the remedy.California Gulch Five-Year Report

Page 76 of 89 15.0 Operable Unit 10 - Oregon Gulch

15.1 Description

The area of OU10 is defined as the 500-y ear floodplain of Oregon Gulch from its headwaters to its confluence with lower California Gulch. The Oregon Gulch tailing impoundments, miscellaneous tailing, and contaminated stream sediment located within the 500-year floodplain of Oregon Gulch are included in OU10. The tailing impoundment is located approximately one- half mile upstream from the confluence of Oregon and California Gulches and contai ns approximately 485,000 cubic yards of material. A map of the post-remedial Or egon Gulch area is provided as Figure 12-1 (Appendix A).

The Oregon Gulch Tailing Impoundment received tailing from the ResurrectionASARCO mill in California Gulch from approximately 1942 through 1957. During removal activities in 1995 and 1996, about 28,00 0 cubic yards of tailing and underlying soil from the Colorado Zinc-Lead (CZL) Ta iling Impoundment were relocated to the Oregon Gulch Tailing Impoundment. An a dditional 550 cubic yards of sediment excavated from the culvert and embankment in California Gulch within OU8 were also deposited on top of the Oregon Gulc h Tailing Impoundment in September 1996.

The stream sediment within the lower porti on of Oregon Gulch has been contaminated with metals from tailing and runoff released from the Oregon Gulch tailing embankment. Release of tailing material was due to erosi on of tailing solids from the embankment that were transported and redeposit ed in the floodplain and stream channel of Oregon Gulch. Release of soluble metals contained in runo ff from the embankment and contained in a seep at the toe of the impoundment had cont ributed to the metal contamination of the sediments. The tailing impoundment had not been in operation since 1957; however, the tailing surfaces were not protected against erosion and continued to contribute tailing solids and contaminated water to downstream areas during periods of runoff until the removal was completed. Table 15-1 presents the types of contamination found in OU10.

Table 15-1 Types of Contamination in Each Media

Media Contamination Sediments Sediments generally display elevated metal concentration and high concentrations of pyrite. Sediments collected at the mouth of Oregon Gulch contain elevated cadmium, iron, manganese, and zinc. Tailing/ Soils Elevated lead and zinc concentrations were found throughout the depth of tailing profiles; while arsenic and cadmium levels decreased as a function of tailing depth. Concentrations of foundation soils underneath the tailing were significantly lower than in the tailing. Seep Water A seep discharges from the base of the tailing embankment year-round. Water quality of the seep discharge is poor, with low pH leve ls and elevated levels of dissolved metals.California Gulch Five-Year Report

Page 77 of 89 Table 15-2 summarizes the chronolo gy of important events in OU10.

Table 15-2 Chronology of Site Events for OU10

Date Event 09/08/83 California Gulch placed on NPL

01/87 Phase I Remedial Investigation Report 1994 Resurrection entered into a Consent Decree and agreed to pe rform certain remediation work in OU10 06/25/95 EE/CA for Stream Sediments within Oregon Gulch 08/04/95 Action Memorandum for PRP Financed Removal Action at the Oregon Gulch Stream Sediments Site 06/97 Removal Action Completion Report 08/08/97 Record of Decision 06/03/98 Operation and Maintenance Plan

11/99 Remedial Action Completion Report 12/05/00 Vegetation Monitoring Report 2/15/01 OU10 nominated for deletion 04/16/01 Operation and Maintenance obligation letter 04/16/01 OU10 is deleted from the NPL

15.2 Response Actions

Response Action Selection/Implementation

Table 15-3 summarizes various Remedial and Removal Actio ns addressed in decision documents.California Gulch Five-Year Report

Page 78 of 89

Table 15-3 Removal and Remedial Actions for OU10

Area Action Memorandum Date and Action Removal or Remedial Action Taken Start Date Completion Date
Oregon Gulch Stream Sediments 08/04/95

Removal Action Construct a channel following the general course of the existing natural stream bed to convey the 10-year 24-hour flood event. The channel serves as a low-flow channel within the 500-year floodplain of Oregon Gulch. The construction included excavating sediments to an average depth of two feet with disposal to the tailing impoundment (specified as Channel Alternative 1 in the EE/CA).

Provide stabilization for the 500-year floodplain by excavating contaminated stream sediment to a depth of one foot in the area outside the constructed channel. The contaminated sediment was placed in the Oregon Gulch tailing impoundment. Borrow soils were placed in the excavated areas to replace contaminated sediment and the area was stabilized and vegetation provided (specified as Stabilization Alternative 3 in the EE/CA).

In the reach of stream potentially identified as a cultural resources site, the existing channel was reconstructed and stabilized (specified as Cultural Resource Alternative 4 in the EE/CA).

Rehabilitate division ditches of OregonGulch tailing impoundment to reduce runon flow to the tailing impoundment and reduce contributions of run-off from the watershed area to the sediment control pond. A temporary sediment control pond was constructed to retain tailing. 09/04/95 and 08/26/96 11/22/95 and 10/15/96California Gulch Five-Year Report

Page 79 of 89 Table 15-3, cont’d Removal and Remedial Actions for OU10

Area Action Memorandum Date and Action Removal or Remedial Action Taken Start Date Completion Date
Oregon Gulch Tailing Impoundment Remedial Action Regrade th e impoundment surface to provide positive drainage.

Install structural fill over the impoundment surface as needed based upon the regraded surface configuration.

Install geosynthetic over the structural fill to control infiltration.

Place 18" thick soil layer with a revegetated surface.

Construct a diversion ditch on the east side of the impoundment to control run-on and run-off.

Construct an upgradient groundwater interceptor trench to limit the infiltration of groundwater into the tailing impoundment.

Develop a deep discharge drain system to manage seep flow from the impoundment
toe. 7/20/98 10/26/98

The 1997 ROD identified the following RAOs:

• Control airborne transpor t of tailing particles

• Control erosion of tailin g materials and deposition in local water courses

• Control leaching and migration of metals from tailing into surface water

• Control leaching and migration of me tals from tailing into groundwater

System Operation/ Operation and Maintenance The following monitoring requirements are im posed under the Final California Gulch Superfund Site Operation and Maintenance Plan , Operable Units 4, 8 and 10 as revised in January 2005.

• Biannual inspection/maintenance of seep collection and conveyance system; top and sideslopes of impound ment cap for differential settlement, vegetation and erosion; and diversion ditches.

• Maintenance of fencing and signage.

The Operation and Maintenance Program has been implemented by Resurrection since September 1999.California Gulch Five-Year Report

Page 80 of 89 15.3 Progress Since the Last Five Year Review

The last site-wide Five Year Review, which was finalized on September 29, 2001, indicated that all of the removal and remedi al actions had been completed and OU10 was deleted from the NPL.

One new seep emanating from the toe of the embankment was identified during the Summer of 2006. This seep repo rtedly has been intercepte d (as of September 2006) and the flow conveyed to the Yak Tunnel Water Treatment Plant.

15.4 Five-Year Review Process

Document Review In preparing this Five-Year Review Repor t, the following documents were reviewed:

• Second Five-Year Review Report

• OU4, OU8 and OU10 Fall 2005 Inspection Report, Resurrection Mining Company

Interviews were conducted with the followi ng individuals to provide supplemental technical information:

3⁄4 Doug Jamison – CDPHE 3⁄4 Mike Holmes – USEPA 3⁄4 Stan Christensen – USEPA 3⁄4 Rebecca Thomas - USEPA

Data Review

• Surface and groundwater quality da ta for the period 1996 through 2005

Site Inspection The Site Inspection was performed on August 24, 2006 by the EPA Remedial Project Manager, Stan Christensen and Kenneth Napp, the HDR Project Manager. The assessment of Site conditions relied heavily on the recent observations of regulatory agency personnel interviewed dur ing this Five-Year Review.

Based on the Site Inspection, conditions documented during the last Five-Year Review and discussions with regulatory agency pe rsonnel, all physical response action elements required under the ROD in OU10 have been constructed and are in working order. However, an uncollected seep was observed emanating from the toe of the impoundment just west of the pump house (See Photo No. 2 – Appendix B).California Gulch Five-Year Report

Page 81 of 89 15.5 Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

• The 2005 Inspection Report described minor amount of accumulated debris in constructed channels as well as ar eas of limited vegetation below the impoundment. A seep identified during the Si te Inspections is being collected and conveyed to the Yak Tunnel Treatment Plan t. However, the continued appearance of contaminated seeps is of potential concern with respect to the long-term protectiveness of the re medy. Access controls are in place at OU10 including fencing and signs installed at the access points to the OU.

• Procedures are in place for notification of EPA and CDPHE should a change in land use be approved by local governments.

• Based on document review, the Site Inspect ion and discussions with regulatory agency personnel, the remedy is largely functioning as intended by the decision documents. However, as discussed unde r Question C, below, the control of leaching and migration of metals from contaminated materials into the surface water may be not have been achieve d to the degree originally intended.

Question B: Are the exposure assumptions toxicity data, and cleanup levels and RAOs used at the time of the remedy selection still valid?

• See Section 3.0 for a discussion of th e Human Health Risk Assessments.

• No new or changed ARARs have been iden tified by the State of Colorado or EPA at the time of this Five Year Re view that would apply to OU10.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

• RAO’s articulated in the ROD requiring, among other things, control of leaching and migration of metals from contaminat ed materials into the surface water, may not have been achieved to the degree or iginally intended. This is indicated by metal loading and concentration trends at a surface water monitoring station in Oregon Gulch for the period 1995 through 2005. The frequent appearance of contaminated seepage from the toe of the constructed embankment may be indicative of lower than expected perfo rmance of the cover system installed on the tailings. Continued m onitoring will be required fo r the potential for seeps from the toe of and down gradient from the impoundment. This issue will be addressed under either OU10 or OU 12 as specified in the 1994 CD.California Gulch Five-Year Report

Page 82 of 89 • The current zoning for industrial/mining is considered to be an IC on land use. However, no ICs exist (or were called fo r in the ROD) to en sure protection of human health in the event of changes in zoning or to prev ent disturbance of engineered remedies as a result of development consistent with current zoning.An Institutional Control Overlay (ICO) District was established to meet postresponse action land use restri ction requirements. However, the ICO District was repealed by Lake County in 2006. As a result, concerns remain regarding protectiveness of the remedy.

15.6 Issues Based on the information collected during th e Five-Year Review, the following issues were identified:

Table 15-4 OU10 Issues Identified

Item No. Issue Affects Current Protectiveness of Remedy Affects Future Protectiveness

of Remedy

1 Additional ICs are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. No Yes

2 Additional seeps have been identified in the toe and downgradient from the impoundment. Yes Yes

15.7 Recommendations and Follow-Up Actions

Table 15-5 OU10 Recommendations for Follow-Up Actions
Item No. Issue Recommendation for Follow Up Party Responsible Due Date

1 Additional ICs are needed to ensure protection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a result of development consistent with current zoning. Prepare an ESD identifying appropriate ICs and implement the controls. Resurrection/ EPA 12/08

2 Additional seeps have been identified in the toe and downgradient from the impoundment. Continue to monitor potential for seeps from the toe of and downgradient from the impoundment and implement seep collection as determined by EPA. Resurrection On-goingCalifornia Gulch Five-Year Report

Page 83 of 89 15.8 Protectiveness Statement

The remedy is protective of human health and the environment. However, future remedial work may be required in orde r to attain final Site-wide water quality standards as determined pursuant to OU12.

The absence of ICs to preclude disturban ce of the remedy under cu rrent zoning has not impacted past or current prot ectiveness as the re medies were undisturbed at the time of this Five-Year Review. However, the potenti al exists for future impacts on remedy protectiveness if such an IC is not developed and implemented. EPA and CDPHE are informally notified by the County of any changes in zoning. Although this is not a formalized IC, it allows the remedy to be protective until an IC is formalized.California Gulch Five-Year Report

Page 84 of 89 16.0 Operable Unit 11- Arkansas River Valley Floodplain

16.1 Description

The remedy for Operable Unit 11 (OU11) se lected in the 2005 ROD has not been implemented. Therefore, this OU was not subj ected to the Five-Year Review process. A summary of prior Response Actions a nd overall OU status is provided below.

Operable Unit 11consists of mine tailing from the Leadville historical mining activity that was transported downstream via California Gulc h to the Arkansas River and deposited in many locations adjacent to the river. Some c ontaminated sediments were also transported along irrigation channels and deposited in fields in the Arkansas River Valley both above and below the 500-year floodplai n. The boundaries of OU11 are from the confluence of the Arkansas River and California Gulch to an area approximately nine miles downstream from the confluence on the Arkans as River (Figure 3-1 Appendix A). The OU is subdivided geographically and also by media into four subunits as follows.

• Irrigated Meadows Area A – 206 acres of pasture in the northern portion of the OU above the 500-year flood plain that exhi bits elevated metals concentrations and acid soil conditions.

• Irrigated Meadows Area B - 148 acres of pasture in the northern portion of the OU above the 500-year flood plain that exhi bits elevated metals concentrations and slightly acid soil conditions.

• Fluvial Mine Waste – 65 acres of mine waste deposits within the 500-year flood plain that are gene rally unvegetated.

• Riparian Areas – 344 acres of vegetated mine waste deposits.

High metal concentrations in fluvially depos ited mine waste has resulted in varying degrees of vegetative distress ranging from diminished plant dive rsity and density in pastures to areas completely devoi d of vegetation along riverbanks.California Gulch Five-Year Report

Page 85 of 89 Table 16-1 summarizes the chronolo gy of important events in OU11.

Table 16-1 Chronology of Site Events for OU11

Date Event 09/08/83 California Gulch placed on NPL.

1986 Investigation study conducted by Colorado Department of Law. 01/87 Phase I Remedial Investigation Report. 06/93 Emergency Response due to high spring run-off threatening severe erosion of a stretch of the Arkansas River bank. 10/28/93 Emergency removal of river tailing.

09/94 Two time critical removal actions to stabilize the embankments of two properties which abutted the Arkansas River. 11/01/94 Emergency removal of river tailing. 09/15/97 Action Memorandum issued for Time Critical Removal Action at the Upper Arkansas - Fluvial Tailing. 08/04/98 Amendment to 09/15/97 Action Memorandum. 06/17/99 Action Amendment issued for Time Critical Removal Action at the Upper Arkansas - Fluvial Tailing 06/09/00 Action Amendment issued for Time Critical Removal Action at the Upper Arkansas - Fluvial Tailing. 08/11/00 Amendment to Action Memorandum dated 06/09/00.

12/04 Feasibility Study 09/05 Record of Decision

16.2 Response Actions

Response Action Selection/Implementation

The remediation of OU11 to date has consis ted of several Removal Actions summarized in Table 16-2.

Table 16-2 Removal Actions for OU11

Area Action Memorandum Date Removal Action Taken/Remedy to be Implemented Start Date Completion Date
Arkansas River, 200 feet upstream from confluence of Lake Fork Creek N/A Steel beams driven into the riverbank and wall of sandbags built to stabilize the river bank. 06/93 06/93

Arkansas River (not specified) 10/28/93 Emergency Removal of tailing along the Arkansas River. 10/28/93 N/A

Arkansas River (not specified) 09/94 Two time critical removal actions to stabilize the embankments of two properties that abutted the Arkansas River 9/94 10/94California Gulch Five-Year Report

Page 86 of 89 Table 16-2, cont’d Removal Actions for OU11

Area Action Memorandum Date Removal Action Taken/Remedy to be Implemented Start Date Completion Date

Arkansas River south of confluence with California Gulch 09/15/97

Amended 08/04/98 Time critical removal action at four locations along stretch of Arkansas River south of confluence with California Gulch. 9/15/97 10/1/99

Arkansas River south of confluence with California Gulch 06/17/99 Time critical removal action at three locations along stretch of Arkansas River south of confluence with California Gulch. Soil amendments were applied and the area revegetated with native species. 6/17/99 11/06

Arkansas River south of confluence with California Gulch 06/09/00

Amended 08/11/00 Time critical removal action at 18 small areas along stretch of Arkansas River south of confluence with California Gulch. Approximately 12,000 cubic yards of tailing were remediated. 06/99 11/06

The ROD describing the selected remedy was released in 2005 and included separate actions for each of four geographi c or media-based areas as follows:

• Irrigated Meadows Area A – Apply lime, d eep till, reseed and implement ICs to

prevent changes in land use unless risks ar e demonstrated to be below a level of

concern.

• Irrigated Meadows Area B - Apply lime, orga nic amendment, deep till, reseed and implement ICs to prevent changes in land use unless risks are demonstrated to be below a level of concern.

• Fluvial Mine Waste - Apply lime, organi c amendment, deep till, reseed and implement ICs to prevent changes in land use unless risks are demonstrated to be below a level of concern.

• Riparian Area - Institutional controls to prevent changes in la nd use unless risks are demonstrated to be below a level of concern.

System Operation/ Operation and Maintenance An Operation, Maintenance and Monitoring Plan will be developed as part of the remedial design.California Gulch Five-Year Report

Page 87 of 89 16.3 Progress Since the Last Five Year-Review

Progress since the last Five Year Review , which was finalized on September 29, 2001 includes the following:

• Completion of all Removal Actions

• Maintenance of the Removal Actions

• Release of the ROD

• Remedial design activities.California Gulch Five-Year Report

Page 88 of 89 17.0 Operable Unit 12

Operable Unit 12 covers the entire California Gulch site and was designated to address Site-wide surface and groundwat er. Under the provisions of the 1994 CD, OU12 will be addressed after completion of source remediation in OUs 2 through 10

. This will include a determination of protectiv eness of surface and groundwater and the establishment of points of compliance and performance standards.

The OU12 Remedial Investiga tion and Feasibility Study were underway at the time of this Five-Year Review with a ROD anticipated to be released in 2008.California Gulch Five-Year Report

Page 89 of 89 18.0 Next Review

This Site required on-going five-year revi ews in accordance with CERCLA §121(c). The next five-year review for the California Gulch Site will be performed five years from the date of completion of this review.

## APPENDICIES

## APPENDIX A

FIGURES

## APPENDIX B

SUMMARY OF PUBLIC COMMENTSAPPENDIX B Community Interviews

Interviews were conducted w ith 17 community members repr esenting city and county government, the county’s advisory group, the count y health department, the Colorado Mountain College, potentially responsible parties, and citiz ens. Most of the interviews occurred one-onone with the exception of one meeting with six representatives of the County’s Institutional Control Advisory Group and three telephone in terviews. The Lake County Commissioners requested that they provide information in writin g, so their concerns are reflected in the summary that follows and their written account is included with the appendixes of the Five-year Review.

EPA received numerous comments that do not dir ectly pertain to the protectiveness of remedy operations at the California Gulch Site. Thes e comments are important and EPA will use them to develop an update of the Comm unity Involvement Plan at a futu re date. Below is a written summary of comments received during interviews as well as written comments from the Lake County Commissioners. EPAs responses are provided (in italics) for those comments pertaining to remedy protectiveness, the subj ect of this 5-Year Review.

Question #1: Are you aware of any community concerns about the California Gulch site or its remedy operations? If so, please detail.

The response to this question va ried dramatically. Three ci tizens and two local government representatives indicated that th ey were unaware of any current community concerns about the site or remedy operations, although one of these ci tizens said she is concerned about her one-year old child. She said she signed up for soil samp ling during the final notif ication period and is anxious to have her property ch ecked and remediated if needed.

Another citizen said that the ove rall community is pretty unfamiliar with the site; he said the public has never seemed to fully appreciate what ha s needed to be done and what still needs to be done. He added that he appreciates the good work EPA has done but that the agency has never really recovered from the negative impacts of co mmunity efforts during the early days. He said the effort has taken much longer than it should ha ve due to public fighting. A different citizen said there seems to be concerns about the n eed for a repository and who would operate it.

Representatives of Lake County and their advi sory group voiced numerou s concerns about the amount of time it has taken to clean up the si te and about economic impacts on the community. Members cited language from the 2001 5-Year Re view about moving the project forward and deleting OU’s, and noted that little has changed over the last 5 years. They said that the community is worn out. One member of the advisory group stated that she be lieves the site is a failure in terms of the (Superfund) process as we ll as the engineered remedies. She said she believes the “administrative process of endless meetings and excessive lawyering doesn’t work, and that she believes their group is being ignored.” Group members described numerous concerns about relations with representatives of EPA and the Colorado Department of Public Health and the Environment.It should be noted that while ex tensive criticism was received from the county and their advisory group, five community members raised concerns a bout the county’s continued fight over issues they felt were solved years ago. Some citizen s said they had concerns about the county’s advisory group because they didn’t feel the gr oup is a representative cross-section of the community. One citizen said he submitted a letter of interest to participate in the county’s advisory group but that he was only given two da ys notice to attend the first meeting and then never heard from the group again.

Question #2: Are you aware of any activities on the site (such as vandalism, trespassing or redevelopment) that may have affected any of the site remedies? If so, please detail.

Most of those interviewed said th ey were not aware of activities th at may have affected the site, however several citizens said they had seen people driving four-wh eelers, dirt bikes, ATVs and snowmobiles in areas where remediation has been conducted. Specifically, one citizen said she was aware of a problem at Hamms Tailings beca use four-wheelers are di gging into the cap. She also said she believes the county is proposing a park there with grassy fields and is curious as to whether native vegetation might be better for the remedy with regard to water usage.

Response No. 1: EPA appreciates the commentors concerns and we lcomes reports on the condition of Site remedies. However, EPA has not noted any breach es in the cover system at Hamms Tailing.

Question #3: What is your overall impression of the remedial acti ons performed to date, and their operation and maintenance?

Responses to this question were either extremel y favorable or extremely unfavorable. Most of those interviewed said they believ ed the remedial actions performed to date were positive. One citizen said he’s had two lengthy tours of EPA’s work in Stray Horse Gulch and that the work appears very stable. A local government representative said he does not have any concerns about remedial actions performed to date and added that he is impressed with the Yak Treatment Plant. Representatives of potentially responsible part ies and contractors ove rseeing some of the nonresidential work activities said they were satisfie d with the remedies; one representative said his only concern is about the need for institutional controls.

Response No. 2 The lack of comprehensive institutional controls (I Cs) has been identified by EPA as an issue of concern for most operable units. EPA is committed to the implementation of ICs in operable units where they are necessary to provide curren t and future protectivene ss before the end of 2007.

Several citizens offered praise fo r the residential work, and one citi zen said his impression is that EPA has done a pretty good job considering that the agency has often had its hands tied. The citizen said it seems that EPA has been swimmi ng against the current and compromised some of its remedies to keep the community happy.Lake County Commissioners and members of thei r advisory group offered numerous criticisms to remedial actions performed to date. Below is a summary of comments received during an interview with the advisory group as well as some statements taken directly from the county’s written comments by operable unit. All writte n comments received by EPA can be found in the appendixes of this report.

Operable Unit 1

The county and members of their advisory group agreed that the Yak has been a positive step forward and they said they hope the treatment pl ant is continued and maintained in an optimal working manner. They said that they believe if the Yak were to be plugged instead of drained through a treatment process, that it would spawn numerous contaminated springs and underground contaminant sources throughout the dist rict spreading contamination that has been mostly contained. They noted that there are seeps below Operable Unit 7, Apache Tailings, which need to be addressed.

Response No. 3: Seeps that are present downstream of Apache Tailing are naturally occurring and are not associated with the remediation feature..

Operable Unit 2

The county and members of their advisory group said that Malta Gulch “looks like a barren desert landscape.” They said it was their opin ion that EPA placed insufficient emphasis on the finish work, and that the tailings pond n eeds to be capped and properly revegetated.

Response No. 4: The Colorado Department of Reclamation Mining and Safety (DRMS) is evaluating reclamation alternatives for the ta iling ponds. Once the DRMS reclamation is completed, EPA will determine whether unacceptable residual risk remain and take additional action, if necessary.

Operable Unit 3

The county and members of their advisory group sa id they believe the Harri son Slag pile should be deleted from the NPL.

Response No. 5: Deletion may be considered once adequate institu tional controls are in place to regulate any future development activities. The need for ICs was identified during this Five-year Review and EPA intends to develop and implement the ICs before the end of 2007.

Operable Unit 4

The county and members of their advisory group said they believe Operable Unit 4 should be deleted from the NPL. They said existing zoni ng (industrial mining) is protective of the remedy.Response No. 6: Institutional controls are needed to ensure prot ection of human health in the event of changes in zoning or to preclude disturbance of engineered remedies as a re sult of development consistent with current zoning. The need for ICs was iden tified during this Fi ve-year Review and EPA intends to develop and implemen t the ICs before the end of 2007. In addition, potentially unacceptable levels of acid mine drainage cont inues to emanate from Operable Unit 4 during periods of high runoff. Therefore, continued mo nitoring will be required before a determination is made on delisting.

Operable Unit 5

The county requested an update on the ASARCO status (what wo rk has been completed and whether any work is to be done in the future).

Operable Unit 6

Members of the county’s advisory group said they believed that several remedies in OU6 are not functioning well. They said remedial work is needed around the waste piles where water has been directed.

The county submitted lengthy comments about OU6:

• They said they believe th e Leadville Mining Drainage Tunnel (LMDT) should remain operational indefinitely and that responsibility should not be transferred to the Colorado Department of Public Health & the Environment.

Response No. 7: EPA is negotiating with the USBOR for federal funding for long-term ope ration of the LMDT.

• They said they consider the surface ponds and collection system for OU6 a failed remedy, and said that the ponds are leaking and contaminating the Arkansas River.The county raised concerns about work conducted at waste dumps and sa id that they don’t intercept groundwater flow toward th e bases of the dumps during runoff.

Response No. 8: Available data indicate that the quantity of zinc and cadmium leaving Stray Horse Gulch has been reduced by approximately 90% since respon se actions were initiated (See OU12 Remedial Investigation Report, EPA 2007). Although some risk of overtopping remains for several retention basins, the overall performance of the remedy is good. In addition, more aggressive reclamation (consolidation and capping) was previous ly rejected by the community because of its adverse effect on historic features.

• The county recommended that EPA contract ors use the Elder pit for tunnel sludges.

• The county also recommended that the Gr eenback, Pyrenees, Ram and Mikado be remined if possible with public approval and to consider recycling the mine spoils for metal recovery.Response No. 9: EPA would consider beneficial reuse of mine wast e by a third party if it were economically feasible.

• The county said they believe seepage from the Mihala pond is contaminating the fresh water ditch across the road to the west and said that most ditches are not properly lined and infiltrate the runoff into the ground.

See Response No. 8:

• The county said they believe work is needed at Starr ditch and 5 th Street because acid mine drainage appears to be ponding in that area.

Response No. 10: EPA presumes the commentor is referring to the small sedimentation pond associated with the 5 th Street headwall. This pond is designed to detain surface flows to allow sediment to settle before the flows are conveyed in a buried pi peline to Starr Ditch. Therefore, the ponding observed is part of normal operation. Sediment removal from the 5 th street headwall structure is planned for 2007.

• The county recommended that an outside t echnical board review the hydrological work performed at the site with recommendations to be addressed as ongoing operation and maintenance of the remedy (not delaying deletion from the NPL).

Operable Unit 7

The county noted in their written comments that there are seeps in Apache Tailings which need to be addressed.

See Response No.3:

Operable Unit 8 The county said they believe the Gaw is incomp lete and poorly understood and that there appears to be some sort of reaction where Gaw water en ters the gulch that ma y indicate some mineral content, possibly zinc contamination. They recommended that EPA run a pump down test that was suggested by Bob Elder.

Response No. 11: The Gaw Shaft will act a relief point once control of water levels in flooded mine workings is established under the OU6 remedy. EPA is negotia ting with the USBOR to permit completion of the OU6 remedy. A pump test of the Gaw Sha ft is planned once negotiations are concluded.

The quality of waters emanating from the Gaw S haft has been tested and generally is good.Operable Unit 9

Members of the county’s advisory group had num erous comments about OU9. Most of the members stated that they believe the OU9 soil remedy has been completely unnecessary and one member said that EPA statistics have shown that there was never a need for the Superfund designation of OU9. The members agreed that they would like to see soil remediation stopped so the (trust fund) money can be used for other h ealth needs. One of the members said they felt Bill Clouber’s work seems to have been dismissed since it came from a grassroots level and their community doesn’t have money. Members noted that the agencies didn’t seem to care about the impact to the community and that the Superf und process seemed to work only in communities that have money.

Members also indicated that institutional controls are not necessary in OU9, and that the Kid’s First program already acts as an institutional control.

One member explained that Leadville’s averag e blood lead is 2.8, only six tenths above the national average blood lead of 2.2, and said that local blood leads ha ve reduced consistently with national levels as a result of redu ced levels of lead in gasoline. This member stated that he does not believe lead in soil is beni gn, but that it is a tiny contributor . He believes that playgrounds and ball fields should have a higher standard (lower action level) but he thinks that the statistics show that dust has not been a c ontributor in residential areas.

The county submitted lengthy comments about OU9:

The county said in their comments that Remedial Action Objectives have been met for OU9 as of the calendar year 2005, and that currently not a single person in OU9 has a blood lead level elevated above 10 ug/dl, the CDC level of con cern. They said they believe the remedy is complete.

The county raised a number of concerns pertaining to EPA’s decision to hold a final notification of the original Lake County Community Heal th Program that resu lted in 165 additional properties. They expressed conc erns about completing the remain ing residential remediation and delaying delisting of OU9 from the National Priorities List.

Response No. 12: The remedy for OU9 requires remediation of prop erties with surface so ils contaminated above established trigger levels. Th e blood monitoring component of the LCCHP and its predecessor, Kids First, was intended to provide an indication of trigger level protectiveness but not remedy completeness. Remedy completeness will not be achieved until all properties have been demonstrated to pose lead risks below a level of concern (probability of blood lead concentration equal or greater than 10 micr ograms per deciliter is less than 5%).

The county said much of the current dispute between them, EPA and CDPHE surrounds the risk presented by the remaining lead in soils and they provided a deta iled account of why they don’t believe further soil remediation or “rigid institutional controls” are necessary. The county said they believe OU9 “meets and exceeds all current U. S. health standards for blood lead levels,”and that “the cost-benefit ratio of soil remediation is so high as to make it a ludicrous course of action, particularly now that so much data is ava ilable at this site and na tionally indicating a very weak link between soil and lead exposure.”

The county urged EPA to take five actions for OU9. Below is an excerpt from the county’s letter of comments:

1. The EPA should immediately transfer the co mplete operation of the LCCHP program to local operation. EPA can complete the 52+165 homes and vacant lots with money from its own budget independently of the county-operated maintenance LCCHP
program. 2. Transfer the Trust to the county per th e Consent Decree and Trust Agreement in order for the county to operate the LCCH P maintenance program. The county fully intends to operate the LCCHP pr ogram for as long as necessary and has submitted a revised work plan to do so. 3. The Consent Decree requires EPA to pr ovide ASARCO with a Certificate of Completion for OU9. EPA should begin the pro cess of deletion of OU9 immediately. It must be top priority fo r EPA to remove the residential areas of Leadville from the stigma of being listed on the NPL. EPA should publicly commit to a timeframe by which time OU9 will be deleted from the NPL and not use the additional homes drummed up for the remediation list to hold up the deletion process.

See Response No. 12.

4. The LCCHP Maintenance program will serve as the institutional control for OU9. The county has offered an init ial three-year period of more intense oversight from CDPHE while the new program becomes completely operational. After that, regulatory oversight should occur during the statutorily mandated 5-year review process where the continued need for the program should be evaluated. The county will make the data available to CDPHE for its own use at any time after the 3-year period. 5. The blood lead level action level for th e maintenance program should remain 10ug/dl. Changes to the acti on level should be based on the CDC national standard and with formal notice and comment amendment to the OU9 ROD.

Response No. 13: EPA is in agreement with this recommendation.

Operable Unit 10

The county said in their written comment lette r that the remedy was failing, has been patched, and may still be at risk of failing. They said that EPA needs to closely monitor the situation.

Response No. 14: The occurrence of contaminated seepage at th e toe and down gradient of the tailing repository has been identified as an issue of concern in this Five-Year Review. EPA will monitor thepotential for continued seepage from the re medy and may require additional response actions either under OU10 or OU12.

Operable Unit 11

The county said in their written comment lette r that they recomme nd maximum removal of contaminated areas in OU11. They said they woul d like to see the remediat ion work result in a more complete cleanup of the fishery. They also said the soil amendments result in only transfer of the metals to vegetation, which die and return to the soil. They said the vegetation will remain dangerous to animals.

Response No. 15: The OU11 Focused Feasibility Study (EPA, 2004) conc luded that an increase in dissolved metals concentrations could not be detected in the Arka nsas River from the up- to the down-stream limit of the Operable Unit. Therefore, recent impacts to water quality from OU11 appear to be small. Risks associated with remobilization of mine wastes during a future flood will be mitigated through stabilization and selective removal of wastes. The risks assessment (EPA, 2004) determined that risks to herbivores (livestock) are below a level of concern in the pasture areas (upland meadow) of OU11. The soil amendment reme dy selected for OU11 will increase plant density and diversity without in creasing risks to livestock.

Operable Unit 12

The county said in their written comment letter th at they do not have a comment at this time; there has not been a proposed plan for OU12. They said, in the interest of moving the entire site to prompt completion and deletion from the NPL, th at they urge EPA to m ove to the final stage of OU12 as quickly as possible, with the incl usion of the Board of County Commissioners and citizen input. They said this comment applies to all operable units at the site that remain on the National Priorities List.

Question #4: Do you feel adequately informed about the Superfund activities?

The majority of those interviewed (13 out of 18) said they did not feel adequately informed about the Superfund activities. Co mmunity members raised concerns about having their primary source of information come from the local newspa pers and they are not sure they hear EPA’s perspective on the issues.

A member of the county’s advisory group said he believes EPA has “stopped communicating with the community and has stiffened up and w ithdrawn.” The county sa id in their written statement that “communication between EPA and the Board of County Commissioners has basically ground to a halt.”

Many of those interviewed offered suggestions for improving communications; examples include distributing EPA fact sheets and/or newsletters directly to citizens; distributing a simple map that identifies areas where construction is complete and where work remains; offering some reviewtime for folks to better understand the history, accomplishments and remaining work; providing a facilitator to resolve major issues; and holding more regular and sometimes smaller meetings.

Question #5: Has the presence of this site had any impact on land use in the area?

Most of those interviewed felt that land use had been impacted and several community members said that the Superfund s ite has likely prevented development of the Union Pacific railroad area (Harrison Street Slag). A coupl e of interviewees also mentioned Apache Tailings as an area negatively impacted by the presence of the site.

Several community members said that either they did not believe land use had been impacted or that the Superfund site had positively affected la nd use. One community member said the site had made a contribution to recrea tional opportunities in the area. Another ci tizen said she thinks that Kids First had a positive impact on resident ial land use and that prospective purchasers have been more comfortable acquiring residential property because they knew the program was available to address their concerns.

Question #6: Are you aware that residual waste will require long-term management, and do you have any concerns about this?

Everyone interviewed was aware th at residual waste will require long-term management, and all but three interviewees expressed at least some level of concern. Representatives of two potentially responsible parties said they were not concerned.

Many of the concerns mentioned pertained to who would be responsible for the long-term management and the associated costs. Severa l citizens emphasized the importance of having a good solid plan in place that can be followed through changes in officials at the local, state and federal level, including agencies such as the Bure au of Reclamation with regard to the Leadville Mine Drainage Tunnel.

The county and members of their advisory group expressed numerous concerns about the Lake County Community Health Program Trust Fund and the Operation and Maintenance Program that will serve as the institutional control for Operable Unit 9.

Also See Question No. 3.

Question #7: Do you have any comments, suggestions or recommendations regarding the site’s long-term management? If so, what type s of future problems do you think either 1) could occur or 2) would concern you at the site?

Most of those interviewed shared comments, suggestions or recommendations regarding longterm management. A couple of community me mbers raised concerns about the Colorado Department of Public Health & the Environment’s ability to stay involved with oversight and to be responsive in a timely manner. One co mmunity member recommended more frequent supervision of the remedies, sp ecifically drainage issues.Several interviewees, including members of the county’s adviso ry group, expressed concern and frustration with the draft Operation and Mainte nance Program for Operable Unit 9. One member of the advisory group said there shouldn’t be any more soil remedies in the residential unit unless an elevated blood lead indicates th e source to be soil, and that he sees the trust f und as a reservoir for continuing lead and other environmental he alth programs for the next 50 years.

See Response No. 12.

A couple of citizens countered these arguments by stating that children should not be used as “guinea pigs” when making decisions a bout investigations and remediations.

One of the advisory group members also pr ovided comments on some of the non-residential operable units and said he believed that “a few touch-ups need to be done at Operable Units 6 and 4, and that more work may be required at OU10.

Question #8: Are you aware of any concerns ab out site impacts on historic preservation?

Several of those interviewed voiced concerns ab out impacts to historic preservation. A few citizens, including a member of the county’s advisory group, raised concerns about the appearance of the “wedding cake.” One citizen said he believes the site has resulted in fewer visits by tourists who like history. Another citizen asked if an arch eologist is still working with the site crew handling residentia l remediations. He voiced con cern about documenting artifacts.

A few community members expressed gratitude to EPA for working with the community to help preserve the history. One citizen said the wo rk done on the Robert Emmet property greatly improved the appearance of the retaining wall and made it less of an eyesore; he said it also improved access to the Mineral Belt Trail.

Question #9: Are you aware of any con cerns about current construction activities?

Most of those interviewed offered no comments or positive comments about current residential construction activities, and one resident said he believed the work was being completed in a professional manner.

One citizen was aware of a residential propert y owner who had a leftover problem from the previous year’s construction season and had to wa it to have it resolved. Some members of the county’s advisory group said they felt the current residential cons truction was a waste of money. One member of the group was concerned because he said he’d seen the construction trucks speeding on the roads.

One comment was received pertaining to construc tion work at the AV Smelter Site in Operable Unit 5. A citizen said he had no ticed lots of dust at the site.Additional Comments:

A resident wanted to know if there were still allo wances as part of the lead-paint remediations. He said he was told he would be given a $250 allowance toward a new front door prior to Asarco’s bankruptcy.

## APPENDIX C

SITE PHOTOGRAPHSPhoto No. 1 – View of FTS 2 (semi-vegeta ted area beyond bare soil) looking to the southwest.Photo No. 2 – Seep at toe of Oregon Gulch capped tailing.