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PACIFIC WESTERN TECHl5oLOGIES LTD L1.9.f.?.yy:.fy.'.'?..^y.?-.L.?*?;..?.°?;.)V.h.?.?.lR!«!9?.C^^^ 

February 23, 2010 

United States Environmental Protection Agency 

ATTN: Stan Christensen, WAM/COR 

US EPA Region 8 

1595 Wynkoop Street 

Denver, Colorado 80202-1129 

Subject: California Gulch Operable Unit 5 

Arkansas Valley Smelter/Colorado Zinc Lead Mill Site 

Final Remedial Action Report, Revision 1 

Work Assignment No. 009-RARA-0829 

Contract No. EP-W-06-006 

Dear Mr. Christensen: 

Pacific Westem Technologies, Ltd (PWT) is pleased to provide Revision 1 ofthe Final Remedial 

Action (RA) Report for the Califomia Gulch Operable Unit 5, Arkansas Valley 

Smelter/Colorado Zinc Lead Mill Site. This RA Report is submitted in accordance with PWT's 

Work Plan, dated February 5, 2009. Revision 1 updated the coordinates on Figure 2 and 

Appendix C to Colorado State Plane coordinates, Central Zone. 

Ifyou have any questions or comments regarding this RA Report, please call me at (303) 274-

5400 x48. 

Sincerely, 

Levi Todd, P.E. 

Califomia Gulch 0U5 AV/CZL Site Project Manager 

Pacific Westem Technologies, Ltd. 

Attachment 

cc: 

James Bush, PWT 

Doug Jamison, CDPHE 

Thomas Roberts, PWT 

File 

www.pwt.com 
FINAL 

REMEDIAL ACTION REPORT 

Revision 1 

REMEDIAL ACTION 

CALIFORNIA GULCH - OPERABLE UNIT 5 

ARKANSAS VALLEY / COLARADO ZINC LEAD SITES 

LAKE COUNTY, COLORADO 

Prepared for: 

^v/ 

US Environmental Protection Agency, Region 8 

1595 Wynkoop Street, 

Denver, CO 80202-1129 

Prepared by: 

^PACIFIC WESTERN TECHNOLOGIES, LTO, 

Pacific Western Technologies, Ltd 

11049 W. 44* Avenue, Suite 200 

Wheat Ridge, CO 80033 

U.S, EPA Contract No. 

Work Assignment No. 

Work Assignment Name: 

Date: 

EP-W-06-006 

009-RARA-0829 

California Gulch OUS 

(AV/CZL Sites) 

February 23,2010 

www.pwt.com 
Table of Contents 

1.0 INTRODUCTION / OPERABLE UNIT BACKGROUND 1 

2.0 CONSTRUCTION ACTIVITIES 2 

2.1 Historical Activities 2 

2.2 2009 Activities 2 

2.2.1 AVSite 2 

2.2.2 CZL Site 3 

2.2.3 AV Consolidation Area Cover 4 

2.2.4 Revegetation 5 

3.0 CHRONOLOGY OF EVENTS 5 

4.0 PERFORMANCE STANDARDS AND CONTRUCTION QUALITY CONTROL 6 

5.0 FINAL INSPECTION AND CERTIFICATIONS 7 

6.0 OPERATION & MAINTENANCE ACTIVITES 7 

6.1 Cover System Inspection and Maintenance 7 

6.2 Institutional Controls 7 

6.3 Groundwater and Surface Water Monitoring 8 

7.0 SUMMARY OF PROJECT COSTS 8 

8.0 FIVE-YEAR REVIEW 8 

9.0 OBSERVATIONS AND LESSONS LEARNED 8 

10.0 OPERABLE UNIT CONTACT INFORMATION 8 

11.0 REFERENCES 9 

Tables 

Table 1 

Figures 

Figure 1 

Figure 2 

Figure 3 

Figure 4 

Figure 5 

APDendices 

Appendix A 

Appendix B 

Appendix C 

Chronology of Events 

Site Location Map 

Final As-Built Survey OU-5 

AV Excavation Areas 

CZL Excavation Areas 2009 

Revegetation/Soil Amendment Areas 

Soil Analytical Results 

Final Remedial Action Inspection Form 

Stamped As-Built Survey 

RA report 009-RARA-0829 Final rev 1 February 23, 2010 

RA Report, Rev. 1 
LIST OF ACRONYMS AND ABBREVIATIONS 

Asarco Asarco Incorporated 

ARAR Applicable or relevant and appropriate requirements 

AV Arkansas Valley 

bgs Below ground surface 

CDPHE Colorado Department of Public Health and Environment 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

COCs Contaminants of Concem 

CQAP Construction Quality Assurance Plan 

CZL Colorado Zinc-Lead 

EPA U.S. Environmental Protection Agency 

HASP Health and Safety Plan 

ICs Institutional controls 

MFG McCulley Frick &Gihnan 

mg/kg Milligrams per kilogram 

O&M Operation and maintenance 

OU Operable Unit 

Platinum Platinum Environmental, LLC 

PM Project manager 

PWT Pacific Westem Technologies, Ltd. 

RA Remedial Action 

RD Remedial Design 

RFE Resident field engineer 

ROD Record ofDecision 

RPM Remedial Project Manager 

SAL Soil Action Levels 

SAP Sampling and Analysis Plan 

SOW Statement of Work 

TSP Total Suspended Particulate 

TTMM Tetra Tech MM 

D 

D 

D 

D 

D 

RA report 009-RARA-0829 Final rev 1 11 February 23, 2010 

RA Report, Rev. 1 D 
U 1.0 INTRODUCTION / OPERABLE UNIT BACKGROUND 

r-] Leadville, Colorado, is located in a mineral rich area ofthe Rocky Mountains where copper, gold, silver, 

i lead, and zinc have been mined intermittently since 1859, when placer gold was discovered in Califomia 

Gulch. Due to past mining, milling, and smelting activities, waste rock, tailings, slag, and smelter waste 

have been dispersed throughout the community. Previous investigations by the EPA and others indicate 

that mining wastes have adversely affected groundwater, surface water, and soil. On September 8,1983, 

EPA placed the Califomia Gulch Superfund Site, comprised ofthe town of Leadville and the adjacent 

mining district, on the National Priorities List. Califomia Gulch Operable Unit 5 (0U5) is comprised of 

the Arkansas Valley Smelter (AV) and Colorado Zinc-Lead Mill (CZL) sites, as well as additional sites 

throughout the Leadville area. The area of OUS consisting ofthe AV and CZL sites is shown on Figure 

1. 

n 

D 

U The Record ofDecision (ROD) for the Califomia Gulch OU 5 AV/CZL Sites was signed in September 

2000. The selected remedy for the OUS AV/CZL sites is excavation of contaminated soils and tailings, 

n consolidation in an on-site repository and placement ofa soil cover over the consolidated material, and 

[J ancillary remedial activities, such as demolition of selected stractures. Constraction activities associated 

with the selected remedy consist of excavation and consolidation of flue dust into an on-site, 

[-1 geomembrane-lined, fully encapsulated repository; demolition to grade of all smelter stractures within the 

I remediated areas except the easternmost oftwo ore bins, the base oftwo smokestacks, and a concrete arch 

(the Dewey Arch); consolidation of tailings, non-residential area soils, and non-salvageable materials at 

O

the AV and CZL sites; and placement ofan 18-inch thick vegetated soil cover over both the flue dust 

repository and the consolidated tailing/non-residential soils. The main contaminants ofconcem (COCs) 

at the site are lead and arsenic in soil and tailings, and, at much higher concentrations, in flue dust. The 

Remedial Design (RD) {Final Remedial Design Report, Arkansas Valley Smelter and Colorado Zinc Lead 

] Mill Site Operable Unit 5, Califomia Gulch Superfund Site) was completed by McCulley, Frick, and 

U Gilman, Inc. (MFG) (now Tetra Tech MM (TTMM)) in April 2005 for Asarco, Incorporated (which 

became Asarco, LLC, hereafter collectively denoted simply as Asarco). 

U MFG, under contract to Asarco, conducted remedial activities at the site during the 2004, 2005,2006, and 

2007 constraction seasons. At the AV site, MFG excavated and consolidated approximately SO percent of 

n the soil and tailings contaminated with lead and arsenic above commercial/industrial standards (non-

{_ residential standards), constmcted a flue dust repository, excavated and placed all identified flue dust 

within the repository, and capped the repository. At the CZL site, MFG excavated and consolidated 

r-| approximately 2,000 cubic yards of non-residential contaminated tailings. In addition, in 2007, borrow 

soil for the cover to be placed over the consolidated contaminated soil and tailing was stockpiled on the 

site. 

I The description ofthe work completed prior to the involvement of Pacific Westem Technologies, Ltd., 

L^ (PWT) is included in MFC's Construction Status Report, Operable Unit 5, Arkansas Valley Smelter and 

Colorado Zinc-Lead Mill Site, Califomia Gulch Superfund Site, Leadville, Colorado, December 2006; 

r and in a technical memorandum from TTMM to Asarco, LLC, dated January 8, 2008. The January 2008 

U memo also includes a description ofthe work needed to complete the Remedial Action (RA). MFG 

previously completed approximately 50 percent ofthe RA. 

J In 2009, EPA directed PWT to complete the RA at the Site under PWT's RAC2 Contract EP-W-06-006, 

and Work Assignment 009-RARA-0829. PWT's Statement of Work (SOW) included updating the RD to 

ri reflect the work conducted to date and remaining work to be completed, procurement ofthe 

I subcontractor, implementation ofthe RA, and close out ofthe RA. PWT retained TTMM's services to 

support the design efforts because of their familiarity and experience with the Site. On May 6, 2009, 

r-, PWT issued a Request for Proposal to prospective bidders to complete the remaining RA at the Site. On 

U 

RA report 009-RARA-0829 Final rev 1 1 February 23, 2010 

1 

U RA Report, Rev. 1 
D 

June 17, 2009, PWT selected and awarded the remediation subcontract for implementing the RA to the 

low bidder. Platinum Environmental, LLC (Platinum). 

2.0 CONSTRUCTION ACTIVITIES 

2.1 Historical Activities 

Asarco, through their contractor MFG, conducted remedial actions at the site during the 2004 through 

2007 constraction seasons. In 2004, demolition activities, primarily associated with the westem ore bin •-

and the Blast Fumace/Ore House buildings, were conducted. In 2005, the flue dust repository was 

constmcted, flue dust was excavated and placed within the repository, as was some ofthe non-residential T 

soils in the consolidation area, and flue-dust repositoiy monitoring wells were installed. In 2006, the L 

contaminated tailings from the CZL site were excavated and consolidated in the AV consolidation area. 

During the 2007 constraction season, approximately 67,000 loose cubic yards of borrow soil from the R 

Lake County Airport borrow area were hauled and stockpiled near the center ofthe AV consolidation area [J 

on top of previously consolidated soil and tailings. The Lake County Airport borrow soil had been 

identified as a suitable source for the consolidation area cover soil. A description ofthe work completed n 

prior to PWT's involvement is included in MFC's Construction Status Report, Operable Unit 5, Arkansas J 

Valley Smelter and Colorado Zinc-Lead Mill Site, Califomia Gulch Superfund Site, Leadville, Colorado, 

December 2006 (MFG 2006); and ui a technical memorandum from TTMM to Asarco dated January 8, r-, 

2008 (TTMM 2008). 

2.2 2009 Activities 

Platinum, PWT's RA constraction subcontractor, conducted and completed constraction activities during 

the period from July 6, 2009, through October 23,2009. The RA constraction in 2009 was completed U 

using the commercial/industrial use standards for Soil Action Levels (SALs) for the COCs lead and 

arsenic that had been identified in MFC's 2005 RD (MFG 2005). These SALs are 6,500 milligrams per f 

kilogram (mg/kg) for lead, and 650 mg/kg for arsenic. The SALs identified in the ROD for L 

commercial/industrial use were 6,100 to 7,700 mg/kg for lead and 610 to 690 mg/kg for arsenic, and for 

recreational use the ROD SALs were 16,000 mg/kg for lead, and 1,400 to 3,200 mg/kg arsenic (EPA T 

2000). All concentrations of COCs that were less than the SALs used for the 2009 constraction activities |_ 

were also below the lower limit ofthe range of commercial/industrial use SALs identified in the ROD. 

2.2.1 AV Site 

After Asarco's remedial activities in 2004 through 2007, MFG identified six areas (Areas 1, 2, 3, 4, 5 and 

6) at the AV site as remaining or potentially remaining to be excavated. Soil in Areas 1,5, and 6 had p 

previously been excavated, but additional confumatory sampling needed to be conducted (MFG 2006). 

Therefore, PWT sampled and analyzed the soil from these areas in accordance with the California Gulch 

Operable Unit 5, Arkansas Valley Smelter cmd Colorado Zinc Lead Site, Remedial Action, Construction |—, 

Quality Assurance Plan, (PWT 2009b) to determine if remediation would be required. Each area was 

subdivided into approximately one-half acre decision areas as necessary, and four random subsamples of 

soil, collected from zero to six inches in depth, were composited from each decision area. The samples 

were analyzed for lead and arsenic by ICP analysis, using EPA method 601 OB. Concentrations of lead 

and arsenic in Areas 1,5, and 6 were below SALs, so no additional remediation activities were conducted ^ 

in these areas (see Appendix A for results). 

Based on previous sampling results conducted by MFG (MFG 2006), and as reflected on the 2009 U 

constraction drawings (PWT 2009a), Area 2 required excavation ofa minimum 1.5-feet of soil. Area 3 

required excavation of a minimum 1 -foot of soil, and Area 4 required excavation of a minimum of 2-feet H 

of soil. All contaminated AV soil was excavated to the design extent and nominal depth, and placed in jJ 

the AV consolidation area and graded to provide positive drainage. Post-excavation surveys indicated 

that the design excavation depths were not achieved in limited or isolated areas. However, it was decided p 

RA report 009-RARA-0829 Final rev 1 2 February 23,2010 

RA Report, Rev. 1 
to conduct confirmatory sampling on the excavated surface rather than conduct "surgical" excavation. If 

any sampled area showed concentrations above SALs, then further excavation would be considered. 

After the initial excavation activities ofthe AV site were completed. Area 2 was split into subareas of 

approximately 0.5-acres each for confirmatory sampling purposes (Figure 3). Confirmatory sampling and 

analyses was conducted in these subareas in accordance with the Constraction Quality Assurance Plan 

(CQAP). One composite sample, comprised of 4 subsamples collected from the upper six inches, was 

collected from each subarea and analyzed for lead and arsenic (PWT 2009b). Composite soil samples for 

each of these areas demonstrated that COCs concentrations in the remaining soil within all of Area 2 were 

below SALs. 

Area 3 was also split into subareas of approximately 0.5-acres each for confirmatory sampling purposes 

(Figure 3). Concentrations of arsenic in subareas 3 A, 3B, and 3E were above SALs. Subareas 3 A, 3B, 

and 3E were excavated by an additional 1.5 feet. After completion ofthe additional excavation, subareas 

3A, 3B and 3E were resampled and analyzed for the COCs. The concentrations of arsenic were still 

higher than the SAL prescribed in the ROD for all three subareas. Based on site knowledge and the 

supposition that it was likely that the contamination extended deeper than another one foot, the U.S. 

Environmental Protection Agency (EPA) Remedial Project Manager (RPM) directed that subareas 3A, 

3B, and 3E not be excavated fiirther, but rather backfilled with borrow soil to a minimum depth of six 

inches. This approach was implemented with the understanding that these subareas do not themselves 

constitute an exposure unit, and that average lead and arsenic concentrations at the site are less than the 

SALs. Placement of backfill is an additional measure that breaks any immediate and localized exposure 

pathway. Subarea 3E received a nominal six inches of soil cover, whereas subareas 3 A and 3B received a 

nominal thickness of 12 inches of soil cover. This backfill was also placed to ensure positive drainage off 

subareas 3B and 3E. 

After initial excavation, sampling results indicated that concentrations of arsenic in Area 4 were above 

SALs. The soil in Area 4 was excavated by an additional two feet and resampled. Area 4 resampling 

results indicated that the concentration of arsenic was still above the SAL. Upon direction from the EPA 

RPM, this area was also backfilled with borrow soil that was a minimum two-feet thick). 

2.2.2 CZL Site 

Three different areas ofthe CZL site were addressed as part ofthe RA (Figure 4): (1) slope area, (2) 

fluvial tailings area, and (3) the designed CZL consolidation area. Both the ROD and MFC's design 

indicated that additional sampling should be conducted in the slope area to more clearly define the extent 

of contamination (EPA 2000, MFG 2006). As an initial sampling screening effort, seven discreet samples 

were collected from the surface ofthe slope area and analyzed for lead and arsenic. Only one discreet 

sample had concentrations of either lead or arsenic that exceeded SALs; however results from several 

other samples were close to the SALs. Based on those results, the CZL slope area was divided into 

nominal 0.5-acre subareas, consistent with the size ofthe sample subareas previously established and used 

at the site in 2005 - 2007, and adjusted to include similar vegetation or disturbance conditions within a 

subarea (see Figure 4). For example, the odd shape for CZL-E3 was partially driven by the fact that this 

shape comprised an area that was vegetated at the time of sampling. In accordance with the CQAP (PWT 

2009b), composite samples were collected from these subareas, each composite comprising generally four 

subsamples (project records provide detailed sampling information) collected from the top six inches of 

the surface, and analyzed for lead and arsenic by ICP analysis, EPA method 601 OB. The sampling results 

indicated that concentrations of lead exceeded SALs in subareas CZL-W2, CZL-W5, CZL-E2, and CZLE6. Contaminated CZL soil in these four subareas was excavated to the extent shown on Figure 4, and to 

a nominal depth of one foot. Upon direction from the EPA RPM, the excavated soil was placed in the 

AV consolidation area. 

RA report 009-RARA-0829 Final rev I 3 February 23, 2010 

RA Report, Rev. 1 
During implementation ofthe RA in the summer of 2009, the CZL consolidation area was eliminated 

from the design and the RA by the EPA RPM. This was possible and appropriate because: 

• The sampling results indicated that soils from only part ofthe CZL slope were 

contaminated, which greatly reduced the volume of CZL soils that required consolidation 

• Excavation of contaminated AV soils and placement in the AV consolidation area had 

progressed to the point where it was recognized that placement of CZL soils in the AV 

consolidation area could be accommodated there without materially affecting the design 

or implementation 

• Subsurface tailings still present in the CZL consolidation area could be excavated and 

consolidated at the AV site, thereby eliminating or reducing a potential source of metal 

loading to Califomia Gulch 

• Elimination ofthe CZL consolidation area eliminated contaminated soils from being 

consolidated adjacent to, and within the historical flood plain of Califomia Gulch. 

D 

After completion ofthe 2009 excavation activities, confirmatory sampling was conducted in accordance 

with the CQAP (PWT 2009b). Results are presented in Appendix A. Confirmatory sampling results 

indicated that concentrations of lead in the "bench" area (comprised ofthe upper parts of CZL-E2, CZLE6, CZL-WS and CZL-W6, as shown on Figure 4) were above SALs. Upon direction from the EPA 

RPM, this area was also backfilled with borrow soil to a minimum thickness of one foot. This approach 

was implemented with the understanding that the bench area does not itself constitute an exposure unit, 

and that average lead and arsenic concentrations at the site are less than the SALs. Placement of backfill 

is an additional measure that breaks any immediate and localized exposure pathway. All areas disturbed 

in the CZL slope during the 2009 constraction activities were surveyed after excavation. 

As provided by the design, and at the direction ofthe EPA RPM, soils from the fluvial tailings area 

(Figure 4) were also excavated and placed in the AV consolidation area. Tailings and other residual 

evidence of tailings were present in the fluvial tailings area, including visual impacts, such as lack of 

vegetation. This excavation was conducted in order to remove visually impacted soil that was suspected 

of being a source of metal loading to Califomia Gulch. Therefore, confirmatory sampling ofthis area was 

not conducted. 

Visually-evident tailings from the CZL "consolidation area" were excavated upon direction from the EPA 

RPM. These tailings were present at a depth of approximately 2 to 3 feet below ground surface (bgs) and 

extended to a depth of approximately 3 to 6 feet bgs, with the depth being greater to the west and 

shallower to the east. A six-inch thick clay zone was observed beneath some ofthe tailings, which might 

have been evidence that the historical tailings area had been lined. The excavated soil was placed in the ^J 

AV consolidation area. The CZL consolidation area was backfilled with borrow soil and graded to 

provide positive drainage into the Califomia Gulch channel. 

— 

2.2 J AV Consolidation Area Cover 

After completion ofthe excavation activities, the AV consolidation area was covered with a minimum of 

18 inches of screened cover soil. The cover soil was from one oftwo sources, either Lake County L 

unscreened borrow soil that was stockpiled on the cover during Asarco activities, or borrow pit soil (see 

Figure 2). Both types of borrow soil were screened such that no particle size greater than 3 inches in n 

diameter was allowed for the cover soil. The cover soil was placed using excavators, dozers, and |J 

scrapers. The eastem half of the southem boundary ofthe AV consolidation cover was graded with a 3:1 

(horizontal to vertical) slope with a diversion berm at the top ofthe slope. This berm is intended to direct r 

RA report 009-RARA-0829 Final rev 1 4 Februaiy 23, 2010 

RA Report, Rev. 1 I 
u 

n 

stormwater sheet flow from the upper east side ofthe cover into a control swale that drains the south 

eastem quadrant ofthe cover (Figure 2). The site was graded in accordance to the design to ensure 

adequate drainage and prevent soil erosion (2% minimum slope, 3:1 maximum slope). 

To prevent stormwater from entering the AV consolidation area and to collect stormwater running off the 

cover, a perimeter stormwater ranon/ranoff ditch was installed. All areas disturbed in the 2004 through 

2009 constraction activities were graded to ensure positive drainage. 

2.2.4 Revegetation 

Upon completion of grading activities, the AV and CZL sites were ripped and tilled for revegetation. 

Approximately twenty samples were collected at various locations for agronomic characteristics to 

provide data used in the evaluation of whether compost addition or pH mitigation of soils was necessary 

as part of revegetation activities. Soil was analyzed for the following: 

pH 

electrical conductivity 

sodium absorption ratio 

cation exchange capacity 

Lime estimate (qualitative) or (calcium carbonate equivalency) 

organic matter 

nitrate-nitrogen 

phosphoras 

potassium 

magnesium 

zinc 

iron 

manganese 

copper 

boron 

sulfate-sulfur 

texture estimates 

fertilizer suggestions for agricultural, horticultural or reclamation applications. 

The concentrations of organic carbon were typically one percent or greater, which are sufficient to 

support revegetation without addition of compost. The values of pH were typically less than 5, except for 

the borrow soil (neutral pH), or in areas where borrow soil had already been placed. Numerous soil areas 

exhibited low pH values unsuitable for revegetation. It was determined that significant cost savings could 

be realized by utilizing excess borrow soil rather than lime for amending the low pH-value soils. 

Therefore, screened borrow soil was placed in areas containing low pH soils to the extent that borrow soil 

was available. A minimum of 6 inches of screened borrow soil was placed in the areas shown in Figure 5. 

Area 2 at the AV site was the only area where lime was added. Pelletized lime was added and tilled into 

the soil in Area 2 at a rate of 30 tons per acre The site was fertilized with 24:4:12 

(nifrogen:phosphate:potash) slow release fertilizer at a rate of 100 pounds per acre. The cover and 

excavated areas were revegetated in accordance with the RD. 

3.0 CHRONOLOGY OF EVENTS 

Table 1 presents the chronology of events at the OU-5 site. 

RA report 009-RARA-0829 Final rev 1 February 23,2010 

RA Report, Rev. 1 
Table 1 - Chronology of Events 

Date 

September 2000 

2004 

April 2005 

2004-2007 

June 19,2009 

July 2009 

October 23,2009 

January 2010 

Event 

Record ofDecision signed for Operable Unit 5 AV/CZL Sites, 

Califomia Gulch Superfimd Site 

Asarco conducted demolition activities at the site 

MFG remedial design approved - Final Remedial Design Report, 

Arkansas Valley Smelter and Colorado Zinc-Lead Mill Site Operable 

Unit 5, Califomia Gulch Superfund Site 

Asarco conducted remedial actions at the site (see narrative) 

2009 PWT design approved- Califomia Gulch Operable Unit 5, 

Arkansas Valley Smelter and Colorado Zinc Lead Site, Remedial 

Action, Constmction Package (PWT 2009a) 

2009 remedial action constmction mobilization 

Final Inspection, site remedial action field work completed 

Final Remedial Action Report 

D 

4.0 PERFORMANCE STANDARDS AND CONTRUCTION QUALITY CONTROL 

Approximately 41 acres of land was remediated at the AV site and approximately four acres of land was 

remediated at the CZL area. All excavated contaminated soil was placed in the 14-acre AV consolidation 

area (Figure 2). The overall goal ofthe project was to cleanup OUS AV/CZL sites to at or below the 

SALs prescribed in the ROD. Upon completion ofthe prescribed remedy in the constraction documents, 

confirmatory soil sampling for the COCs was conducted. The soil in the excavated areas met SALs after 

initial and additional excavation, if necessaiy, with minor exceptions. Concentrations of arsenic in soil in 

four areas remained above action levels. All four areas are located in the AV site: Area 3A, Area 3B, 

Area 3E, and Area 4 (Figure 3). Subareas 3A & 3B were backfilled with a minimum of 12 inches of 

borrow soil, subarea 3E was backfilled with a minimum of 6 inches of borrow soil, and Area 4 was 

backfilled with a minimum of 2 feet of borrow soil, as directed by the EPA RPM. Average 

concentrations ofthe COCs for the entire AV site are below the SALs for the COCs. 

Environmental sampling and analysis was conducted in accordance with EPA guidelines and the CQAP 

(PWT 2009b). Soil sample results for both the AV and CZL areas are included in Appendix A. Realtime air monitoring for total suspended particulates (TSP) was conducted daily using a MiniRAM® 

during constraction activities. Air monitoring results never exceeded action levels. All sampling 

methods and data were verified and 20 percent were validated. 

Excavation on site was performance based. AV and CZL areas had to be excavated to different depths 

per the constraction drawings. The resident field engineer (RFE) field-verified excavation depths. In 

addition, pre- and post-excavation surveys were conducted on the individual areas. Survey data were 

independently reviewed by PWT's project engineer to verify soil depths. The AV consolidated area was 

field-verified by the RFE, and survey data was verified by PWT's project engineer to ensure that final 

grading provided positive drainage. 

The final cover ofthe AV consolation area required positive drainage and an 18-inch thick cover of 

screened borrow soil. Cover soil particle size was field-verified throughout the screening process by the 

RFE. Soil depth thickness on the cover was confirmed on site by the RFE and confirmed by PWT's 

RA report 009-RARA-0829 Final rev 1 February 23, 2010 

RA Report, Rev. 1 
project engineer based on pre- and post constraction surveys preformed by the subcontractor. Density 

testing (ASTM D-2922 and ASTM D-698) was performed on the placed cover soil at a frequency of 

every 1.5 acres by the Remediation Subcontractor, and wimessed by the RFE. All density tests results 

were above the required density requirements. The control swale, ditches, and drainage stractures were 

constructed per the constraction documents. All water diversion feature materials and grading was 

verified by RFE. 

5.0 FINAL EVSPECTION AND CERTIFICATIONS 

Informal prefinal inspections were conducted on all areas as excavation and other constraction activities 

were completed in individual subareas. Punch-list items identified as part of these prefinal inspections 

were addressed as constraction progressed. 

A final site inspection was completed on October 23, 2009. The EPA RPM, PWT's project manager 

(PM), RFE, and the remediation subcontractor were present for the final inspection. At the time ofthe 

final inspection no items were found that required resolution. EPA accepted the work as complete. The 

Remedial Action Inspection form is presented in Appendix B. 

Health and safety was a major concem for the project. PWT, the remediation subcontractor, all other 

subconfractors, and all other personnel were required to follow the provisions in their respective HASPs 

(on file at PWT). During the 2009 constraction activities no health and safety incidents, lost time 

accidents, or near-misses were recorded. 

6.0 OPERATION & MAINTENANCE ACTIVITES 

This section presents a brief outline of recommendations for long-term operation and maintenance (O&M) 

ofthe remedy, including cover-system inspection and maintenance, non-cover remediation area 

inspection and maintenance, surface-drainage confrols inspection and maintenance, and groundwater 

monitoring and institutional controls (ICs). 

Recommendations for O&M for the consolidation area are summarized in Section 6.1 below. However, the 

non-cover areas that were remediated as a part ofthe remedial action for OUS project should also be inspected. 

The run-on and run-off control features associated with the AV and CZL sites should be inspected periodically. 

Visual inspection should be conducted of all drainage ditches, berms, chutes, swales, channels, and culverts to 

verify operation, capacity, and the effectiveness of erosion control measures. 

6.1 Cover System Inspection and Maintenance 

The primary exposure-pathway barrier for the AV consolidation site is an 18-inch soil cover. In addition, flue 

dust materials are contained within a fully encapsulated geomembrane liner, covered by between 4 and 8 

feet of nonresidential area soils, and the final 18-inch clean soil cover. The boundary ofthe 

repository is represented by the flue dust monuments as shown on Figure 2. The soil cover should 

be inspected for indications of excessive differential settlement, erosion, cracking, sloughing, ponding, or 

other potential problems that may affect the integrity or performance ofthe cover system. The success of 

vegetation efforts should also be assessed. 

6.2 Institutional Controls 

The ROD requires implementation of ICs as a component ofthe remedy to provide notification that a barrier 

is in place, and to restrict land use to protect the integrity ofthe remedy in the cover areas (EPA 2000). It is 

understood that the EPA, Colorado Department of Public Health and Environment (CDPHE) and Lake 

County Commissioners are working to develop ICs for the Califomia Gulch OUS AV/CZL sites. 

RA report 009-RARA-0829 Final rev 1 7 February 23, 2010 

RA Report, Rev. 1 
D 

6.3 Groundwater and Surface Water Monitoring 

An element ofthe ROD remedy is to establish a long-term monitoring program to assess the quality of 

surface water and groundwater following implementation ofthe remedy (EPA 2000). Three groundwater 

wells (one upgradient and two downgradient ofthe repository) were installed by MFG and extended by 

PWT (Figure 2). Groundwater and surface water for the overall Califomia Gulch Superfund sites were 

included within a separate operable unit, 0U12. Any groundwater and surface water monitoring 

requirements for OUS should be integrated with monitoring requirements for OUl2. 

7.0 SUMMARY OF PROJECT COSTS 

The ROD identified the estimated remedy capital cost of approximately $2.85 million. Work performed in 

2009 under the PWT contract was approximately $1.5 million. The cost for RA work performed in previous 

years by Asarco is not public information. 

8.0 FIVE-YEAR REVIEW 

Because the contaminated tailings, flue dust, and non-residential area soils will remain on site, the 

Selected Remedy requires a five-year review under Section 121 of CERCLA, and Section 

300.430(f)(4)(ii) ofthe National Contingency Plan. The five-year review includes a review ofthe 

groundwater and surface water monitoring data and an evaluation as to how well the Selected Remedy is '-' 

achieving the RA objectives and applicable or relevant and appropriate requirements (ARARs) that it was 

designed to meet. 

9.0 OBSERVATIONS AND LESSONS LEARNED 

The presence of previously stockpiled borrow soil on top of previously consolidated contaminated soil and 

within the consolidation area created placement issues for the additional contaminated soil that needed to be 

placed within the consolidation area, survey issues to properly document the top ofthe consolidated soil 

surface and thickness of soil cover; and logistical issues with respect to sequencing of consolidation, cover 

placement, and surveying. When work is conducted at a project over multiple years, it is important to 

consider how current actions, which may need to be taken immediately because of schedule constraints, 

affect the overall plan for execution ofthe work though completion ofthe project. 

10.0 OPERABLE UNIT CONTACT INFORMATION 

• Stan Christensen, EPA RPM. 

US EPA Region EPR-SR 

1595 Wynkoop Street 

Denver CO 80202-1129 

Christensen.Stanley@epa.gov 

(303) 312-6694 phone 

(303)312-7151 fax 

• Levi Todd, P.E., Project Manager 

Pacific Westem Technologies, Ltd. 

11049 West 44* Avenue 

Suite 200 

Wheat Ridge CO 80033 

LTodd@pwt.com 

(303) 274-5400 x48 phone 

RA report 009-RARA-0829 Final rev 1 8 Februaiy 23, 2010 

RA Report, Rev. 1 
(303) 274-6160 fax 

• Rick Anacleto, Remediation Subconfractor 

Platinum Environmental, LLC 

401 West County Road 16 

Loveland CO, 80537 

(970)-669-2277 phone 

(970)-669-2382 fax 

11.0 REFERENCES 

MFG, Inc. 2005. Final Remedial Design Report, Arkansas Valley Smelter and Colorado, Zinc-Lead Mill 

Site, California Gulch Superfund Site. April. 

MFG, Inc. 2006. Construction Status Report, Operable Unit 5, Arkansas Valley Smelter and Colorado 

Zinc-Lead Mill Site Califomia Gulch Superfund Site, Leadville, Colorado. December. 

Pacific Westem Technologies, Ltd. (PWT). 2009a. California Gulch Operable Unit 5, Arkansas Valley 

Smelter and Colorado Zinc-Lead Mill Site, Remedial Action, Construction Package. June. 

Pacific Westem Technologies, Ltd. (PWT). 2009b. Califomia Gulch Operable Unit 5, Arkansas Valley 

Smelter and Colorado Zinc-Lead Mill Site, Remedial Action, Construction Quality Assurance 

Plan. July. 

Tetra Tech. (TT), January 8,2008. Technical Memorandum to Asarco, LLC. California Gulch Superfund 

Site, OUS - A V Smelter Site and CZL Mill 2008 Construction Activities. 

U.S. Environmental Protection Agency (EPA). 2000. Record of Decision - Operable Unit 5, A V/CZL 

Sites, California Gulch Superfund Site, Leadville, Colorado. September. 

RA report 009-RARA-0829 Final rev 1 9 February 23, 2010 

RA Report, Rev. 1 
r 

Figures 

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RA report 009-RARA-0829 Final rev 1 February 23, 2010 

RA Report, Rev. 1 
h APPROXIMATE 

ALIFORNIA GULCH 

r^ OUS. AV/CZL v 

BOUNDARY / ' 

] 

2000 ft 

] /TACIRCWESTERNTECHNOLOGES.LTD. 

11049 West 44th Avenue, Suite 200 

Wheat Ridge, CO 80033 

303-274-5400 WWW.PWT.COM 

SITE LOCATION MAP 

CALIFORNIA GULCH OPERABLE UNIT 5 

AV/CZL SITES LEADVILLE, CO 

FIGURE 1 

NO. I BY IDATEibtefct^lPTIOTT 

PROJECT: 

California Gulch OUS 

0 ^ B^TGNED BY: 

I-12-2Q1 

APPR6VED BY: 

201C 

n 

L 

LEGEND: 

2009 DESIGN EXCAVATION AREAS 

2009 DESIGN AREA NOTATION 

CONFIRMATORY SAMPLING 

DESIGNATION 

ASARCO EXCAVATION AREAS PRIOR 

TO 2009 CONSTRUCTION 

ACTIVITIES NOT REQUIRING 

ADDITIONAL EXCAVATION 

5 

® 

* CONCENTRATIONS OF ARSENIC IN THESE DESIGNATED AREAS EXCEEDED THE SOIL ACTION LEVELS AT THE FINAL EXCAVATION 

DEPTH. THESE AREAS WERE BACKFILLED WITH BORROW SOIL TO A DEPTH OF 6 TO 24 INCHES. 

/PACIFIC WESTERN TECHNOLOGIES, LTO. 

11049 West 44th Avenue, Suite 200 

Wtieat Ridge, CO 80033 

303-274-5400 WWW.PWT.COM 

AV EXCAVATION 

AREAS 

CALIFORNIA GULCH OPERABLE UNIT 5 

AV/CZL SITES LEADVILLE, CO 

NO. BY I DATE I DESCRIPTION 

PROJECT: 

California Gulch OUS 

DATE: 

DESIGNED BY: 

1-12-2010 

APPROVED BY: 

JMB 

j j m 

200 ft 

FIGURE 3 
APPROXIMATE 

CALIFORNIA 

GULCH OUS, 

AV/CZL 

BOUNDARY 

/ 

y 

/ 

LEGEHD: 

EXCAVATED FLUVIAL TAILING AREA 

EXCAVATED TAILINGS AREA 

EXCAVATED SLOPE AREA 

SAMPLING AREA BOUNDARY 

SAMPLING AREA DES/GNATION 

EXCAVATION CRITERIA: 

SAL 

VISUAL TAILINGS 

VISUAL TAILINGS 

CZL-E1 

N 

NOTE: SOIL IN SAMPLING AREAS CZL-W2, CZL-W5, CZL-E2 AND CZL-E6 CONTAINED 

CONCENTRATIONS OF COCs ABOVE SALs. EXCAVATION IN THESE AREAS WERE FIELD FIT AROUND 

EXISTING MILL STRUCTURES. EXCAVATION IN CZL-E3 OCCURRED AS A RESULT OF PUSHING 

CONTAMINATED SOIL FROM CZL-E6 DOWNSLOPE. 

11049 WMt 44tti AMiHit. Sulta 200 

WhMtRMo*. CO 80033 

303-274-6400 WWW.PVIT.COM 

CZL EXCAVATION AREAS 

2009 

CALIFORNIA GULCH OPERABLE UNIT 5 

AV/CZL SITES LEADVILLE, CO 

NO. I BY I DATE I DESCRIPTTON 

PROJECT: 

California Gulch OUS 

DATE: 

DESIGNED BY: 

1-12-2010 

APPROVED BY: 

TWR 

JM 

100 ft 

FIGURE 4 
BORROW AREAS 

LEGEND: 

NO REVEGETATION 

AREA WITH A MINIMUM 6" SOIL 

BACKFILL & STANDARD SEED MIX 

AREA WITH NO SOIL AMENDMENT 

& STANDARD SEED MIX 

AREA WITH LIME SOIL TREATMENT 

& STANDARD SEED MIX 

AREA WITH A MINUMUM 6" SOIL 

BACKFILL & DITCH SEED MIX 

AREA WITH SOIL BACKFILL & 

DITCH SEED MIX 

AREA WITH A MINIMUM 6" SOIL 

BACKFILL & WETLAND MIX 

OVERSIZED ROCK AREA 

^ii'^.)i:-y.ii 

11040 WMt 44lh AvMwa. Suttt 200 

WhMtRMga. CO 80033 

303-2744400 WWW.PWr.COM 

REVEGETATION/SOIL 

AMENDMENT AREAS 

CALIFORNIA GULCH OPERABLE UNIT 5 

AV/CZL SITES LEADVILLE. CO 

NO.I BY IDATEIDESCRIPTRUR 

PROJECT: 

California Gulch OUS 

PATE; 

DESIGNED BY: 

1-12-2010 

APPROVED BY: 

J3/ffi 

Am 

300 ft 

FIGURE 5 
Appendix A 

Soil Analytical Results 

RA report 009-RARA-0829 Final rev 1 February 23, 2010 

RA Report, Rev. 1 
Arkansas Valley Site - Soil Analytical Results 

Pre-Excavation AV Area 

Sample ID 

AVI 

AV 1-02 

AV5E 

AV5W 

AV6 

Date Sampled 

7/9/2009 

7/9/2009 

7/10/2009 

7/10/2009 

7/10/2009 

Arsenic 

448 

341 

204 

45.9 

36.8 

Lead 

5,830 

5,020 

2,510 

128 

205 

Post-Excavation AV Area 

Sample ID 

AV4 

AV4 

AV2A 

AV 2A-02 

AV2B 

AV 2B-02 

AV2C 

AV2D 

AV2E 

AV2F 

AV2G 

AV2H 

AV2I 

AV2J 

AV2K 

AV3A 

AV3A 

AV3B 

AV3B 

AV3C 

AV3D 

AV3E 

AV 3 E-02 

AV3E 

BORROW 1 

BORROW 2 

Date Sampled 

8/17/2009 

9/15/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/18/2009 

8/27/2009 

9/3/2009 

8/27/2009 

9/15/2009 

8/27/2009 

8/27/2009 

8/27/2009 

8/27/2009 

9/15/2009 

8/27/2009 

8/27/2009 

Arsenic 

1,300 

770 

4.86 

3.55 

12.8 

15.2 

4.01 

6.94 

26.8 

116 

9.54 

112 

33.3 

100 

30 

2,010 

1,460 

1,570 

1,1 70 

491 

257 

2,020 

2,100 

428 

182 

113 

Lead 

ND 

249 

81.7 

58 

150 

221 

32.8 • 

52.5 

279 

330 

284 

1,330 

104 

1,030 

152 

1,090 

183 

767 

137 

131 

72.9 

310 

386 

99.2 

1,180 

621 

Notes: 1. See Figure 3 from sampling areas 

2. Each sample generally was a composite of four subsamples form the sampling area. 

Specific subsample locations are in the project files. 

3. All samples are expressed in mg/kg 

4. All items identified in red are above Soil Action Levels 

Page 1 of 1 
Colorado Zinc Lead Site - Soil Analytical Results 

Pre-Excavation CZL Area - Discreet Screening Samples 

Sample ID 

CZLl 

CZL 2 

CZL 3 

CZL 4 

CZL 5 

CZL 6 

CZL 7 

Date Sampled 

7/9/2009 

7/9/2009 

7/9/2009 

7/9/2009 

7/9/2009 

7/9/2009 

7/9/2009 

Arsenic 

30.2 

621 

22.3 

86 

160 

274 

86.6 

Lead 

1,730 

9,670 

624 

1,180 

5,600 

6,180 

1,190 

Pre-Excavation CZL Area - Com 

Sample ID 

CZL E-1 

CZL E-2 

CZL E-3 

CZL E-4 

CZL E-5 

CZL E-6 

CZL W-1 

CZL W-1-02 

CZL W-2 

CZL W-3 

CZL W-4 

CZL W-5 

CZL W-6 

Date Sampled 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

8/3/2009 

posite Samples 

Arsenic 

80.3 

152 

64.1 

53 

30.8 

135 

129 

160 

145 

257 

125 

23.5 

85.2 

Lead 

3,750 

10,900 

1,340 

1,550 

4,590 

7.550 

4,630 

5,720 

8.220 

5,460 

2,780 

14,400 

4,230 

Post-Excavation CZL Area 

Sample ID 

CZL S-B 

CZL Slope-E 

CZL Slope-W 

Date Sampled 

9/1/2009 

9/8/2009 

9/8/2009 

Arsenic 

93.3 

33.8 

26.4 

Lead 

H.\W 

1,120 

1,240 

Notes: 1. See Figure 4 from sampling areas 

2. Each sample generally was a composite of four subsamples form the sampling area. 

Specific subsample locations are in the project files. 

3. All samples are expressed in mg/kg 

4. All items identified in red are above Soil Action Levels. 

5. CZL S-B is a sample collected from the bench ofthe CZL slope. 

Page 1 of 1 
Appendix B 

Final Remedial Action Inspection Form 

D 

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RA report 009-RARA-0829 Final rev 1 February 23, 2010 

RA Report, Rev. 1 
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CtaUfomia Guich OV5 

Arkansas Vallcy/Colonido,2%i6 Lead Sitss 

Lain Covniy* Colondo 

Final RaniMilai Aciion Inspection 

bGtDlier.23,20a9 

AiElMly 

ftiinpllniawl analywsitf Atfaniw^vaMwiiibawM 15,6 

Excavation of AVsubaraas odntaMniKGoiioenftratipm of faad brarranic 

•nwlar tJwn sctftw teweb 

RamadM Action J 

Canmhiad? 

Yes 

Yes 

Cpnllnnatory wmpHngand aiialwesirf AVsufaeas t Si and4 

Ad»BtlonalwgawattirfcfiWsiifcWBM.9iind>r 

ConsoHdattenofeMBwaiBdAVaoBliiconwiMatlonaiea 

Stwenftitt ofMocfcplled cewaoll 

Hacamentaf ttrliich aoii^ 

Yes 

ves 

Yes 

Yes 

ConnnictionofteimandiHwIeoncow 

Gonstructton of AV iMnminterninoq/ifundf control inteii, Including 

InttallalioniBftwfDadMefts 

SaiamllBt antf-anahieesaf'Ca.ilope 

Yes 

Yes 

ves 

Yes 

Buavatlon of GEL subaraas containing eoheentfttlons of (aad or 

anenlfriTBalierthin action tewh 

ConflrnBaterywmpHng end analwes of WBawatrtiCa. areas 

AtfWonal^vaBonofCaa.wdiaieBS' 

-

Ekcawatlon of catamnss area based on visual obserwattons 

Yes 

Yes 

Yes 

BackBII of ca.talBnis awe to ftcilltala dralnega 

AironbmlcsainpllBgefAVandClLeieas 

Mitigation of low pH aoAs by Ome amendnieht or placemiint of 6-Inch 

lift of bonow soil ., 

Yes 

Ves 

L 

Rev^talion of AV and OL areas iHsturiiad during 2009 and previous 

vears 

Biuipnient demobilliBd and sltia cleaned up 

Yes 

Yes 

Yes 

1. 

2. 

SoU oontalnhv imric •bow ictloin tavais Wis taft th plice III M M 4and porttom of Aiea 9 at a depth tf 

or mom bataw itaitfni |iaA. Thate araas wail biGlMted with C In ^ or mam of irarfew 

MIltmialaaitflmiatlonareaplhofaallcBMrwasMaHlMrnaairanlplHestaeai^ 

rMfMibili Iwfna andiftw p!|pm«^ aiid sehedi*fer oampMbig 

tfniafvrriMunNiy. 

Soli eoiitalplng laad afaoimelM tavali was laft In place In tha 'upper barnih area" or GZl. Onafbbt ef bomw 

llnthlsi 

PWT 

Platlnuni 
Appendix C 

Stamped As-Built Survey 

RA report 009-RARA-0829 Final rev 1 February 23, 2010 

n 

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a. I o 

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