SFUND RECORDS CTR

2101943

Site Inspection ReportZeibright Mine

Nevada City, California

EPA ID No.: CAN000905925USAGE Contract No.: DACA45.98.D0004, Task Order 25

Work Order No.: 20074.025.165

January 2005

Prepared for:U.S. Environmental Protection Agency

Region 9

Prepared by:Weston Solutions, Inc.

Table of Contents

Section Page

1.0 INTRODUCTION 11.1 Apparent Problem 1

2.0 SITE DESCRIPTION 22.1 Location 22.2 Site Description 2

2.3 Operational History ._ 32.4 Regulatory Involvement 3

2.4.1 United States Environmental Protection Agency 3

2.4.2 California Department of Toxic Substances Control 32.4.3 California Department of Health Services, Drinking Water Field Operations

Branch 42.4.4 California Department of Conservation, Office of Mine Reclamation 42.4.5 Nevada County Department of Environmental Health 4

3.0 INVESTIGATIVE EFFORTS 43.1 Previous Samp ling and Analyses 4

3.1.1 California Department of Conservation, Office of Mine Reclamation 4

3.1.2 Department of Toxic Substances Control 43.2 Current EPA Sampling 5

3.2.1 Deviations From the Samp ling and Analysis Plan 6

4.0 HAZARD RANKING SYSTEM FACTORS 74.1 Sources of Contamination 7

4.2 Groundwater Pathway 74.3 Surface Water Pathway 8

4.3.1 Hydrologjcal Setting 8

4.3.2 Surface Water Targets 84.3.3 Surface Water Pathway Conclusion 9

4.4 Soil Exposure and Air Pathways 9

5.0 EMERGENCY RESPONSE CONSIDERATIONS 10

6.0 SUMMARY 11

7.0 REFERENCE LIST '. 13

List of Tables

Section Page

Table 3-1. June 2004 Low Concentration Soil Samp ling Results for Total Metalsand Cyanide 14

Table 3-2. June 2004 Low Concentration Sediment Samp ling Results for Total Metalsand Cyanide 17

Table 3-3. June 2004 Low Concentration Surface Water Samp ling Results for Total Metalsand Cyanide 19

Table 3-4. June 2004 Low Concentration Groundwater Samp ling Results for Total Metalsand Cyanide 21

list of Figures

Section Page

Figure 2-1. Site Local ion Map 22Figure 3-1. Sample Location Map 23

List of Appendices

Appendix A: Transmittal ListAppendix B: Site Reconnaissance Interview and Observation Report/Photographic

DocumentationAppendix C: Contact Log and Contact ReportsAppendix D: Latitude and Longitude Calculations WorksheetAp p endix E: ReferencesAppendix F: EPA Quick Reference Fact SheetAppendix G: Sampling and Analysis PlanAppendix H: Analytical Results

List of Acronyms

bgs Below Ground SurfaceCERCLA Comprehensive Environmental Response, Compensation, and Liability

ActCERCLIS Comprehensive Environmental Response, Compensation, and Liability

Information SystemCLP Contract Laboratory Program

DEH Nevada County Department of Environmental HealthDTSC Department of Toxic Substances ControlEPA United States Environmental Protection Agency

HRS Hazard Ranking SystemMCL Maximum Contaminant Level^g/L Micrograms per Liter

mg/kg Milligrams per KilogramNOAA National Oceanic and Atmospheric AdministrationNPL National Priorities List

OEHHA California Office of Environmental Health Hazard AssessmentOM R Office of M ine ReclamationPA Preliminary Assessment

PRO Preliminary Remediation GoalQAMS United States Environmental Protection Agency Quality Assurance

Management SectionRCRIS Resource Conservation and Recovery Information SystemSAP Sampling and Analysis PlanSARA Superfund Amendments and Reauthorization Act of 1986SI Site InspectionSQuiRT Screening Quick Reference TableTAL Target Analyte List

USGS United States Geological SurveyWESTON Weston Solutions, Inc.

1.0 INTRODUCTION

The United States Environmental Protection Agency (EPA), Regjon 9, under the authority of theComprehensive Environmental Response, Compensation, andLiability Act of 1980 (CERCLA) andthe Superfund Amendments and Reauthorization Act of 1986 (SARA), has tasked Weston Solutions,Inc. (WESTON) to conduct a Site Inspection (SI) of the Zeibright Mine site in Nevada City, NevadaCounty, California.

The Zeibright Mine site was identified as a potential hazardous waste site and entered into theComprehensive Environmental Response, Compensation, and Liability Information System(CERCLIS) on May 2, 2002 (CAN000905925) (I).

A Preliminary Assessment (PA) of the Zeibright Mine site was completed for the EPA by theDepartment of Toxic Substances Control (DTSC) on July 11, 2002. The purpose of the PA wasto review existing information on the site and its environs to assess the threat(s), if any, posed topublic health, welfare, or the environment, and to determine if further action under CERCLA/SARAis warranted.

After reviewingthe PA, the EPA decided that further investigation of the Zeibright Mine site wouldbe necessary to completely evaluate the site usingtheEPA's Hazard RankingSystem(HRS)criteria.The HRS assesses the relative threat associated with actual or potential releases of hazardoussubstances at the site. The HRS has been adopted by the EPA to help set priorities for furtherevaluation and eventual remedial action at hazardous waste sites. The HRS is the primary methodof determining a site's eligibility for placement on the National Priorities List (NPL). The NPLidentifies sites at which the EPA may conduct remedial response actions. This report summarizesthe results of the SI for the Zeibright Mine site.

More information about the Superfund program is available on the EPA web site athttp://www.epa.gpv/superfund. A fact sheet describingthe EPA's site assessment process can befound in Appendix F.

1.1 Apparent Problem

The apparent problems at the site, which contributed to the EPA's determination that an SI wasnecessary, are presented below.

The former Zeibright Mine was an active mining facility from 1918 to 1959. The primary oremineral mined during operation was gold. Other minerals consisted of pyrite, chalcopyrite, andpyrrhotite associated with quartz veins in metamorphic slate. Metals such as arsenic, lead, andmercury are commonly associated with mine tailings in this region of the Sierra Nevada Mountain

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Range, known as the "Motherlode" gold belt, where the Zeibright Mine site is located. Large minetailings waste piles are located on site with concentrations of metals and arsenic that exceed the EPAresidentialPreliminary Remediation Goal (PRO) andCaliforniaM odified PRO (non-cancer endp oint)for soil.

Currently, a portion of the site operates under the name Donner Mine Camp, Inc., as arecreationalcamp ing facility. Visitors and nearby residents are potentially exposed to metals from access to themine tailings. Areas within the Donner Mine Camp property are overlain with tan to light brownmine tailings and light brown to grey waste rock. One such area, the "Ball Field", is an area severalthousand square feet in size, used for outdoor recreational game activities, including soccer andvolleyball. Some short grasses have colonized this area due to the presence of organic matter inmanure piles located throughout the field. Another area consisting of mine tailings and waste rockis called the "Corral". Mine tailings are located in a road cut adjacent to the Corral. Cementing ofthe tailings has occurred in this area.

Approximately 2,000 feet west of the Ball Field and the Corral is an area containing large tan to lightbrown mine tailings piles several acres in size and approximately 30 to 50 feet in height. This areais referred to as the "Sand Dunes". These p iles are used by local residents and Donner M ine Campvisitors for recreational activities such as "sliding" down the slopes of the piles. These piles areabsent of vegetation and access is not restricted.

Mine tailings located within the Donner Mine Camp property encroach on the Bear River. Theactive recreational fishing industry associated with the Bear River andthe Rollins Reservoir, locatedapproximately 15 miles downstream, has been issued a health advisory due to high levels ofmethylmercury found in fish.

2.0 S1TE DES CRIPTION

2.1 Location

The Zeibright Mine site is located at 12707 Zeibright Road, 2.5 miles northeast of Blue Canyon,Nevada County, California. The geographic coordinates for the site are 39° 17' 00.21" north latitudeand 120°43' 28.81" west longitude. The location of the site is shown in Figure 2-1.

2.2 Site Description

The extent of the historical Zeibright Mine property is estimated to be approximately 100 acres.Donner Mine Camp occupies approximately 17 acres of the former Zeibright Mine site. The

Zeibright Mine site sits at an elevation of approximately 4,100 feet above mean sea level and isbounded by the steep, densely forested (tall pine and fir) terrain of northern Bear Valley. The siteflanks the Nevada/Placer County border just north of the Bear River. United States InterstateHighway 80 is located approximately 1 mile southeast of the site and California State Highway 20is located approximately 1 mile northeast of the site (2).

Donner Mine Camp features include a historical mineral assay building, hotel, and mine structuressuch as a head frame and mill foundations. Donner M ine Camp also has its own museum, which isfeatured on the "Old Zeibright Mine Tour". The walking tour also includes a visit to theBlacksmiths Cabin and Shop, Changs Building, Main Lodge, the Tunnel, and Mill Site (2).

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2.3 Operational History

I The former Zeibright Mine was owned and operated by the Bear Valley Mining Company fromj 1918 to 1934, the Empire Star Mines Company from 1934 to an unknown date, and the Numont; MiningCompany from an unknown date to 1959. The primary ore mineral mined duringoperation- was gold. Other minerals consisted of pyrite, chalcopyrite, and pyrrhotite associated with quartzi veins in metamorphic slate. Millingoperationsinvolvedtheuseof ajaw crusher, ball mill, classifier,

and amalgamation tables. In later years, ore was processed usingfloatation cells and cy anidation thatgenerated significant hazardous by-products. A stamp mill was also used at some point duringoperation (2).

Current operations at the site include recreational camping facilities for non-profit youth groups.Originally purchased in 1959 from the Numont Mining Company by Daniel W. Beatie and hisfamily, theproperty was given to the Buttes Area Council of the Boy Scouts of America for a year-round camp operation. The camp was renamed for the Donner Party, who passed through thevalley. Donner Mine Camp operated between 1960 and 1970 under an Agreement and Option to

; Re-buy in 1971 by the Beatie Family and Tenco Tractor, Inc. of Sacramento. The currentowner/operator is Mr. Dan Beatie, under the name Donner Mine Camp, Inc. Donner Mine Camp

I became incorporated in 1980 as a non-profit organization available to charitable and educational! organizations for family retreat and camping programs in an effort to protect and preserve the group

camp operation and the history of the Zeibright Mine. It operates on the user fees collected eachseason and donations of individuals and companies from the Grass Valley, Nevada City, and thegreater Sacramento Area (3).

Most of the original mine buildings remain in good condition and several have been converted forcamp use. The original hotel (the Main Lodge), which historically housed miners, is now used as adormitory for campers, along with the other indoor sleepingarea, the Change Building, where minerschangedtheirclothes and showered after workingin the mine. Donner Mine Camp can accommodateup to 300 visitors at 30 campsites, up to 60 visitors in the Main Lodge (which can also seat 150

people in the kitchen), and up to 60 visitors in the Change Building. Donner Mine Camp operatesseasonally from May through October with a caretaker living on site year-round (2, 3).

2.4 Regulatory Involvement

2.4.1 United States Environmental Protection Agency

The Zeibright Mine siteis not listed in the Resource Conservation and Recovery Information System(RCRIS) database, as of October 9, 2003 (4).

2.4.2 California Department of Toxic Substances Control

DTSC conducted a site visit on October 25, 2001 and a samp ling effort on November 19, 2001, todetermine the potential risks to Donner Mine Camp visitors using the mine tailings for recreationalactivities. This samplingevent was limited to the immediate Donner Mine Camp property and didnot include an investigation of the larger mine tailings piles (the Sand Dunes), the water andsediments of the Bear River, or the groundwater from the private drinking water well servingDonnerMine Camp. The site was scored using the HRS, and the PA was completed on July 11, 2002 (1,

2).

2.4.3 California Department of Health Services, Drinking Water Field Operations Branch

The Donner Mine Camp, Inc. Transient Non-Community Water System was classified as a WaterSource Protection Area under the California Drinking Water Source Assessment and ProtectionProgram by the California Department of Health Services, Drinking Water Field Operations Branchin October 2002. A summary of the report shows a very high vulnerability ranking to historicmining operations for theon-site drinking water well. The discussion of vulnerability states that ofthe constituents tested for, there have been no chemical contaminants detected in the water supply,but that the physical barriers of the site are not effective in preventing the movement ofcontaminants into the aquifer (5).

2.4.4 California Department of Conservation, Office of Mine Reclamation

Limited qualitative sampling for mercury, arsenic, and cyanide, conducted by the CaliforniaDepartment of Conservation, Office of Mine Reclamation (OMR), was completed in January 1999.According to the OMR report, Zeibright Mine ceased operations on December 31, 1942 (6).

2.4.5 Nevada County Department of Environmental Health

The water from the private drinking water well in Donner Mine Camp is tested regularly by theNevada County Department of Environmental Health (DEH). A test for lead on May 13, 1988,revealed non-detectable levels with adetection limit of 8 micrograms per liter (|Ag/L). In March 2001,DEH noted that Donner Mine Camp visitors were using mine tailings piles for recreational activitiesand referred the site to DTSC (2, 3).

3.0 INVES TIGATIVE EFFORTS

3.1 Previous Sampling and Analyses

3.1.1 California Department of Conservation, Office of Mine Reclamation

Limited qualitative sampling for mercury, arsenic, and cyanide was completed by the CaliforniaDepartment of Conservation, OMR in January 1999. The detection limits of the analytical methodare not known and the results are reported as null (6).

3.1.2 Department of Toxic Substances Control

DTSC conducted a samp ling effort on November 19, 2001 and collected a total of 15 soil/tailingssamples. All samples were analyzed for metals using EPA Method 6010B. Six samples wereanalyzed for mercury using the Coleman Model SOD, Reference EPA Method 7471A (2).

Four of the seven samples located in the Ball Field had arsenic concentrations exceeding theestablished PRO (non-cancer endpoint) for residential soil of 21 milligrams per kilogram (mg/kg).The two samp les collected in a road cut near the Corral and the two samp les collected near the AssayBuilding all had arsenic concentrations below the established PRO (non-cancer endpoint) forresidential soil. All four samples located in the Camp Ground (reference samples outside ofsuspected mine tailings areas) also showed arsenic concentrations below the established PRO (non-cancer endpoint) for residential soil (2).

All seven samples located in the Ball Field revealed lead concentrations that exceed the CaliforniaModified PRO for residential soil of 130 mg/kg. Two of these samples also exceed the EPA PROof 400 mg/kg. All samp les located in the Corral and the Camp Ground had concentrations below theestablished PRGs for residential soil. One sample located outside of the Assay Building had a leadconcentration of 1450 mg/kg, the highest concentration recorded for any sample in the study (2).

None of the six samples analyzed for mercury showed concentrations that exceed the establishedPRO (non-cancer endpoint) of 22 mg/kg (2).

3.2 Current EPA Sampling

On June 1 and 2, 2004, WESTON, under the direction of the EPA, conducted a samp ling event attheZeibright Mine site. In accordance with the protocol described in the April 2004 SamplingandAnalysis Plan (SAP) (AppendixG), soil samples were collected from mine tailing? piles throughoutthe site, water and sediment samp les were collected from the Bear River and Rollins Reservoir, andgroundwater samples were collected from the private on-site Donner Mine Camp drinking waterwell. Sample locations are shown in Figure 3-1. All samples were analyzed by the ContractLaboratory Program (CLP) Target AnalyteList (TAL) Inorganics Method, and the analytical datawere validated by the EPA Quality Assurance Management Section (QAMS).

Soil samp ling results indicate levels of arsenic, lead, and iron above the established EPA PRGs forresidential soil (non-cancer endpoints) with the highest readings at 57.9 mg/kg, 6,940 mg/kg, and73,300 mg/kg, respectively. Antimony, barium, cadmium, mercury, selenium, zinc, and cyanideconcentrations were all below the established EPA PRGs for residential soil (non-cancer endpoints)with the highest readings at 9.2 mg/kg, 301 mg/kg, 1.4 mg/kg, 3.0 mg/kg, 14.2 mg/kg, 830 mg/kg, and25.0 mg/kg, respectively (Table 3-1).

Bear River and Rollins Reservoir sediment samples revealed metals concentrations similar tobackground samples, with the exception of one source and one release sample from the Bear Riverthat revealed lead concentrations of 67.7 mg/kg and 35.1 mg/kg, respectively (Table 3-2). Thisrelease sample is below the National Oceanic and Atmospheric Administration (NOAA) publishedreference value for contaminated sediment. The lowest toxicity NOAA Screening Quick ReferenceTable (SQuiRT) value for lead is 37 mg/kg (7). The presence of antimony, barium, cobalt, selenium,and thallium in Bear River source and release samples and Rollins Reservoir release samples, is notattributable to the site and published reference values from the NOAA SQuiRTs are not available

(7).

Bear River and Rollins Reservoirsurfacewatersample results indicate the presence of barium, cobalt,lead, nickel, and zinc in source and release samples. The highest levels of these analytes was foundto be 28.5 |ag/L, 11.0 ng/L, 2.2 ng/L,,22.7 ug/L, and 56.0 ng/L, respectively (Table 3-3). Theconcentrations of lead, nickel, and zinc are all below published NOAA SQuiRT values (7). Bariumand cobalt are not attributable to the site.

The groundwater pathway was not evaluated due to the lack of background wells and targets,however, the on-site well was sampled for human health purposes. As shown in Table 3-4, theresults were compared to established Maximum Contaminant Levels (MCLs), or health-basedbenchmarks. None of the analytes exceed current MCLs. See AppendixH for the complete resultsof the June 2004 EPA samp ling event.

3,2.1 Deviations From the Sampling and Analysis Plan

Field modifications to the April 2004 SAP were as follows:

• Sample location ZM-S-S1 was taken from a metal salts tailings pile on the north sideof theDonner Mine Camp unpaved road across from the Corral.

• Sample location ZM-SW-R3/ZM-SED-R3 was moved to the base of the seep at sample

location ZM-SW-S6yZM-SED-S6 due to lack of access in the downstream reaches of theBear River.

• Source sample ZM-SW-S4/ZM-SED-S4 was not collected due to this seep being dry; arelease sample, ZM-SW-R8/ZM-SED-R8, was collected at the point where the seep met theBear River.

' • Source sample ZM-SW-S2/ZM-SED-S2 was not collected due to this seep beingalmost dry

. • (a trickle of flow was observed but was not substantial enough to collect the sample); arelease sample,ZM-SW-R10/ZM-SED-R10, wascollectedbelow the seep in the Bear River,directly below the Ball Field.

Source sample ZM-SW-S3/ZM-SFJD-S3 (and duplicate sample ZM-SW-S7/ZM-SED-S7)' were not collected due to this seep being dry; a release sample, ZM-SW-R9/ZM-SED-R9,1 and duplicate sample ZM-SW-R11/ZM-SED-R11, were collected at the point where thej seep met the Bear River.

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1 • Release sample ZM-SW-R4/ZM-SED-R4 was not collected as there was no access to the] lower downstream reaches of the Bear River via Zeibright Mine/Donner Mine Camp roadsI or trails and no land access to the Bear River upstream of the Rollins Reservoir.

j • Releasesample location ZM-SW-R5/ZM-SED-R5 (and duplicatesampleZM-SED-R6) was! moved to the downstream end of the Rollins Reservoir as there was no land access to the

Bear River where it flows into the Rollins Reservoir.

4.0 HAZARD RANKING S YS TEM FACTORS

4.1 Sources of Contamination

For HRS purposes, a source is defined as an area where a hazardous substance has been deposited,stored, disposed, or placed, plus those soils that have become contaminated from migration of ahazardous substance.

Potential hazardous substance sources associated with the Zeibright Mine site include, but may notbe Limited to:

• Contaminated Soil: Metals such as arsenic, lead, and mercury are commonly associated with

mine tailings in the region where the Zeibright Mine is located. Large mine tailings wastepiles are located on site with concentrations of metals that exceeded the EPA residentialPRGs and California Modified PRGs (non-cancer endpoint) for soil sampled in theNovember 2001 DTSC study (2). The June 2004 EPA-sponsored samplingevent indicatesthat levels of arsenic, lead, and iron are significantly above background levels in the on-sitemine tailings piles.

4.2 Groundwater Pathway

In determining a score for the groundwater migration pathway, the HRS evaluates: 1) the likelihoodthat sources at a site actually have released, or potentially could release, hazardous substances togroundwater; 2) the characteristics of the hazardous substances that are available for a release (i.e.,toxicity, mobility, and quantity); and 3) thepeople (targets) who actually have been, or potentiallycould be, imp acted by the release. For the targets component of the evaluation, the HRS focuses onthe number of people who regularly obtain their drinking water from wells that are located within4 miles of the site. The HRS emphasizes drinking water usage over other uses of groundwater (e.g.,food crop irrigation and livestock watering), because, as a screening tool, it is designed to give thegreatest weight to the most direct and extensively studied exposure routes.

Groundwater in the reach of the Bear River that borders the Zeibright Mine site and Donner MineCamp is contained within fractured bedrock. Water for domestic use is extracted from two privatewells located on the Donner Mine Camp property, ranging between 70 and 150 feet below groundsurface (bgs). Only the deeper of thesetwo wells is used tosupply drinking water to residents andvisitors. Donner Mine Camp houses one caretaker year-round and can accommodate up to 420guests at a time during the operating months of May through October. Six residences are widelyscattered within 0.25 mile of the site (2). According to 2000 Nevada County census information,there are 2.47 persons per household, resulting in an approximate population of 14.82 within 0.25mile of the site (8). Nine wells are located within 4 miles of the site, however, none of these wellsare used for drinking water (9).

The groundwater pathway was not evaluated due to the lack of background wells and targets,however, the on-site well was sampled for human health purposes. As shown in Table 3-4, the

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results were compared to established MCLs, or health-based benchmarks. None of the analytesexceed current MCLs.

4.3 Surface Water Pathway

In determining the score for the surface water pathway, the HRS evaluates: 1) the likelihood thatsources at a site actually have released, or potentially could release, hazardous substances to surfacewater (e.g., streams, rivers, lakes, and oceans); 2) the characteristics of the hazardous substances thatare available for a release (i.e., toxicity, persistence, bioaccumulation potential, and quantity); and3) the people or sensitive environments (targets) who actually have been, or potentially could be,impacted by the release. For the targets component of the evaluation, the HRS focuses on drinkingwater intakes, fisheries, and sensitive environments associated with surface water bodies within 15miles downstream of the site.

4.3.1 Hydrological Setting

The Bear River is the major drainage for the Zeibright Mine site and is bounded by steep terrain asit flows southwest alongthe southern boundary of the site. Overland drainage is obvious as the minetailings piles exhibit erosion channels leadingto the river. Ferecretestaining(red) was observed alongthe active runoff channels and stratification of the slurry deposit was noted during the sitereconnaissance. The Conner Mine Camp caretaker, Lin Stanchfield, also explained that adam/impoundment was located alongthe Bear River and was destroyed in 1939 due to high flows(Appendix B).

Due to the encroachment of the mine tailings piles and the steep terrain as previously noted,sediments and runoff from the mine tailings enter the Bear River along with seeps from the geologicformation in which mining occurred. The Bear River continues to flow southwest into RollinsReservoir, located approximately 15 miles downstream of the site, and ultimately disperses into theSacramento River (2).

4.3.2 Surface Water Targets

There are no drinking water intakes associated with the Bear River or Rollins Reservoir (AppendixC-l, C-3, C-6, and C-7). Both of these surface water bodies support active fisheries. RollinsReservoir also supports camping, water sports, and other recreational activities. Elevated levels ofmethylmercury in fish associated with the Bear River watershed have been documented by theUnited States Geological Survey (USGS) and pose a threat topiscivorous wildlife and humans (10).The California Office of Environmental Health Hazard Assessment (OEHHA) has issued a healthadvisory for the Rollins Reservoir (11).

Accordingto the EPA GIS Report for theZeibright Minesite, the only State designated threatenedor endangered species within the target distance limit of 15 miles from the site are the MountainYellow-Legged Frog, the California Red-Legged Frog, and the Lahontan Cutthroat Trout (9).

4.3.3 Surface Water Pathway Conclusion

A release to surface water is established when a hazardous substance is detected in a downstreamwater or sediment sample at a concentration that is at least three times greater than the concentrationdetected in an upstream water or sediment sample, and some portion of the release is attributable tothe site, or when a hazardous substance is detected in a downstream water or sediment sample andnot detected in an upstream water or sediment sample, and some portion of the release is attributableto the site.

Based on the results of the June 2004 EPA-sponsored sampling effort as discussed in Section 3.2,a release of hazardous substances attributable to theZeibright Mine site to the Bear River or RollinsReservoir is currently not documented, however a source of arsenic, lead, and iron was establishedin the on-site mine tailings piles.

4.4 Soil Exposure and Air Pathways

In determining the score for the soil exposure pathway, the HRS evaluates: 1) the likelihood thatthere is surficial contamination associated with the site (e.g., contaminated soil that is not coveredby pavement or at least 2 feet of clean soil); 2) the characteristics of the hazardous substances in thesurficial contamination (i.e., toxicity and quantity); and 3) the people or sensitive environments(targets) who actually have been, or potentially could be, exposed to the contamination. For thetargets component of the evaluation, the HRS focuses on populations that are regularly andcurrentlypresent on or within 200 feet of surficial contamination. The four populations that receive the mostweight are residents, students, daycare attendees, and terrestrial sensitive environments.

In determining the score for the air migration pathway, the HRS evaluates: 1) the likelihood thatsources at a site actually have released, orpotentially could release, hazardous substances to ambientoutdoor air; 2) the characteristics of the hazardous substances that are available for a release (i.e.,toxicity, mobility, and quantity); and 3) the people or sensitive environments (targets) who actuallyhave been, or potentially could be, impacted by the release. For the targets component of theevaluation, the HRS focuses on regularly occupied residences, schools, and workplaces within 4miles of the site. Transient populations, such as customers and travelers passingthrough the area,are not counted.

There are no residences, schools, or daycare centers on the same property and within 200 feet ofcontamination associated with the site (Appendix B).

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5.0 EMERGENCY RESPONSE CONSIDERATIONS

The National Contingency Plan [40 CFR 300.415 (b) (2)] authorizes the EPA to consider emergencyresponse actions at those sites that pose an imminent threat to human health or the environment.For the following reasons, a referral to Region 9's Emergency Response Section does not appear tobe necessary:

• Based on the results of the June 2004 EPA-sponsored sampling effort, a release ofhazardous substances attributable to the Zeibright Mine site to the Bear River orRollins Reservoir is currently not documented, however a source of arsenic, lead, andiron from the mine tailings piles was established.

• There are no residences, schools, or day care centers on the same property and within200 feet of contamination associated with the site (Appendix B).

• A release of hazardous materials from the site to the private Donner Mine Campdrinking water well is currently not documented.

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6.0 SUMMARY

The Zeibright Mine site is located at 12707 Zeibright Road, 2.5 miles northeast of Blue Canyon,Nevada County, California. The extent of the historical Zeibright Mineproperty is estimated to beapproximately 100 acres. The Zeibright Mine site sits at an elevation of approximately 4,100 feetabove mean sea level and is bounded by the steep, densely forested (tall pine and fir) terrain ofnorthern Bear Valley. The site flanks the Nevada/Placer County border just north of the Bear River.United States Interstate Highway 80 is located approximately 1 mile southeast of the site andCalifornia State Highway 20 is located approximately 1 mile northeast of the site.

Donner Mine Camp occupies approximately 17 acres of the former Zeibright Mine site. DonnerMine Camp features include a historical mineral assay building, hotel, and mine structures such asa head frame and mill foundations. M ost of the original mine buildings remain in good condition andseveral have been converted for camp use. The original hotel (the Main Lodge), which historicallyhoused miners, is now used as a dormitory for campers, along with the other indoor sleeping area,the Change Building, where miners changed their clothes and showered after working in the mine.

The former Zeibright Mine was owned and operated by the Bear Valley Mining Company from1918 to 1934, the Empire Star Mines Company from 1934 to an unknown date, and the NumontMiningCompany from an unknown date to 1959. The primary ore mineral mined during operationwas gold. Other minerals consisted of pyrite, chalcopyrite, andpyrrhotite associated with quartzveins in metamorphic slate. Milling operations involved the use of a jaw crusher, ball mill, classifier,and amalgamation tables. In later years, ore was processed usingfloatation cells and cyanidation thatgenerated significant hazardous by-products. A stamp mill was also used at some point duringoperation. Current operations at thesite include recreational camp ing facilities for non-profit youthgroups.

Regulatory involvement includes limited qualitative sampling for mercury, arsenic, and cyanide,completed by the California Department of Conservation, Office of Mine Reclamation, as part ofthe Abandoned Mine Report for Zeibright Mine in January 1999. The water from the privatedrinking water well in Donner Mine Camp is tested regularly by the Nevada County Departmentof Environmental Health (DEH). In March 2001, DEH noted that Donner Mine Camp visitors wereusing mine tailings piles for recreational activities and referred the site to the Department of ToxicSubstances Control (DTSC). DTSC conducted a site visit on October 25,2001 anda samplingefforton November 19,2001, to determine the p otential risks to Donner M ine Camp visitors. The DonnerMine Camp, Inc. Transient Non-Community Water System was classified as a Water SourceProtection Area under the California Drinking Water Source Assessment and Protection Program bythe California Department of Health Services, Drinking Water Field Operations Branch in October2002.

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The following pertinent Hazard Ranking System factors are associated with the site:

• Based on the results of the June 2004 EPA-sponsored sampling effort, a release ofhazardous substances attributable to the Zeibright Mine site to the Bear River orRollins Reservoir is currently not documented, however a source of arsenic, lead, andiron from the mine tailings piles was established.

• There are no drinking water intakes associated with either the Bear River or Rollins

Reservoir and limited human food chain targets.

• A release of hazardous materials from the site to the private Donner Mine Camp

drinking water well is currently not documented.

• Nine wells are located within 4 miles of the site. None of these wells are used for

drinking water.

• There are no residences, schools, or day care centers on the same property and within

200 feet of contamination associated with the site.

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7.0 REFERENCE LIST

1. United States Environmental Protection Agency (EPA), Superfund Information Systems,CERCLIS Database, http://cfpub.epa.gpv/supercpad/cursites/csitinfo.cfm?id=0905925, dataextracted September 17, 2003.

2. California Department of Toxic Substances Control, Preliminary Assessment, Zeibrigjit Mine,May 15, 2002 (completed July 11, 2002).

3. Donner Mine Camp, Inc., "The Old Zeibrigjit Mine", Camp ground Information Package, 2001.

4. EPA, Resource Conservation and Recovery Act (RCRA Info), Query Results,http://oaspub.epa.gpv/enviro/, data extracted October 9, 2003.

5. California Department of Health Services, Drinking Water Field Operations Branch, DrinkingWater Source Assessment, Donner Mine Camp, Inc., Nevada County, Transient Non-community Water System, Well 01, October 2002.

6. California Department of Conservation, Office of Mine Reclamation, Abandoned Mine Report,Zeibright, October 3, 2001.

7. NationalOceanicandAtmosphericAdministrationvCoastaI Protection andRestorationDivision,Screening Quick Reference Tables, Hazmat Report 99-1, September 1999.

8. United States Census Bureau, State and County QuickFacts, Nevada County, California,http://quickfacts.census.gpv/qfd/states/06/06057.html, 2000.

9. EPA, Region 9, GIS Center, Site Report for State of California, Zeibright Mine, October 28,2004.

10. United States Geologic Survey, Mercury Bioaccumulation in Fish in a Region Affected byHistoric Gold Mining: The South Yuba River, Deer Creek, and Bear River Watersheds,California, 1999.

11. California Office of Environmental Health Hazard Assessment, Health Advisory for SelectedWater Bodies in the Northern Sierra Nevada Foothills (Nevada, Placer, and Yuba Counties),http.7/www.oehha.ca.gov/fish/so_cal/nosierra.htrhl, December 12, 2003.

14

EmmigraiGap

Zeibnght Mine Enlargement

LEGEND

• Sample Location

D Structure

Mine Tailings

ZM-SW-R5/ZM-SED-R5/ZM-SED-R6 (dup.)

Note: Surface water and sediment samplestaken concurrently at same field location.

Sample Location M;Zeibright Ml

304-0105 Fig3-1.ai

Table 3-1June 2004 Low Concentration S oil S ampling Results for Total Metals and Cyanide (mg/kg)

(results significantly above background are bolded and underlined1)Sample

LocationSample

DateLocation

Description

EPA Preliminary RemediationGoal (PRO) (non-cancer

endpoint except')

Alu

min

um

76,000

Ant

imon

y

31

ZM-S-BG1

ZM-S-BG2

6/1/04

6/1/04

Upgiadientofminetailings

Upgradientof minetailings

12,400

16,000

ND(6.0)

ND(6.0)

Arc

enic

22

Bar

ium

5,400

E_3

1n

150

Cad

miu

m

37

Chr

omiu

m

210*

5

900*

o,o.ou

3,100

i

23,000

,

400

£>

23

Background Samples

3.2

2.6

29.8J

48.2

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

36.6

20.fi

10.2

6.5

31.4

21.8

21,300

16,500

8.8

10.2

ND(0.10)

ND(0.10)

I

1,600

30.7

13.5

Sele

nium

390

C

390

Tha

llium

5.7.

ND(3.S)

ND(3.5)

1.0

1.3

2.6

ND(2.5)

Van

adiu

m

78

40.7

55.9

ua

23,000

uT3

1XU

1,200

53. 2J

60.7J

3. 63

3.1

Source Samples

ZM-S-Sl

ZM-S-S2

ZM-S-S3

^4

ZM-S-S5

ZM-S-S6

ZM-S-S7

ZM-S-S8

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

Conal

Conal

Conal

Conal

Ball Field

Ball Field

Ball Field

Ball Field

6,330

8,570

8,100

7,310

H.100

14,300

7,500

7,800

6.5J

ND(6.0)

ND(6.0)

ND(6.0)

ND(6.0)

ND(6.0)

ND(6.0)

ND(6.0)

20.4

15.8

33.4

519

13.9

12.8

-

17.3

186

188

120

192

S7.7

79.2

177

167

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

ND

(0.50)

ND(0.50)

ND(0.50)

U

Li

M

U

M

0.22

Mi

Mi

5.1

14.7

17.0

10.4

34.S

36.4

8.7

10.7

10.2

7.0J

6.7J

8.4J

13.7]

13.4J

8.7J

8.7J

58.6

70.8J

75.2J

10U

1053

80.23

74.1J

53. 4 J

60.900

59.500

59,200

73.300

43,700

42,100

58,400

47,200

445

277

471.

689

243

197

301

177

ND(0.10)

0.88J

0.823

0.20J

0.513

0.383

0.423

0.076J

6.7

9.9

12.4

9.6

29.2

31.0

8.5

10.3

11.4J

9.3

U

ill

8.0

TA

9.2

8.0

ND(1.0)

ND(1.0)

1.5

1.2

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

3.6

4.1

2.7

ND

(2.5)

2.9

ND(2.5)

3.4

3.6

11.8

18.1

17.3

20.3

22.0

22.8

17.4

17.2

153J

174

148

165

208

182

137

117

9.03

4.43

12.8

25,0

1L7

3.7

ill

7.4

Table 3-1June 2004 Low Concentration Soil Sampling Results for Total Metals and Cyanide (mg/kg)

(results significantly above background are bolded and underlined1)Sample

Location

ZM-S-S9

ZM-S-S20(duplicateofZNitS-

S9)

ZM-S-S10

ZM-S-S11

ZM-S-S12

ZM-S-S13

ZM-S-S14

ZM-S-S15

ZM-S-S16

ZM-S-S17

SampleDate

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

6/1/04

LocationDescription

Mineralassay

building

Mineralassay

building

Mineralassay

building

Mineralassay

Mineralassay

building

Sand Dunes

Sand Dunes

Sand Dunes

Sand Dunes

Sand Dunes

Alu

min

um24,400

26,700

11,000

33,500

21,500

7.720

12,000

1,340

8,090

10,300

Ant

imon

y

ND(6.0)

ND(6.0)

ND(6.0)

6£J

ND(6.0)

6.6J

9J.J

6A]

ND(6.0)

ND(6.0)

Ajs

enic

14.1

14,0

2M

IM

15.8

1.1

4.3

ND(1.0)

5.2

4.2

Bar

ium

92.7

96.0

78.5

100

104

301

261

37.9

217

167

Ber

ylliu

m

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

ND(0.50)

Cad

iriu

m

0.91

1.0

ND(0.50)

1.4

ND(0.50)

0,55

1.3

ND(0.50)

M

Li

Chr

omiu

m

27.2

31.2

40.8

30.9

33.4

,4.9

12.6

1.1

10.4

13.3

•§.as9.8J

10.7J

9.3

11.9

10.3

ND(5-0)

ND(5.0)

ND(5.0)

8.2J

5.8J

fea.a.oU

72.5]

89. 6 J

47.2

35.8

46.9

6.0

20. 9J

ND(2.5)

25. U

22.5J

a£

31,400

35.400

39,800

34,500

39,800

43,300

59,900

8,170

61,000

56.000

HJ

366

353

6.940

153

174

5.2

95,2

4.6

m

2L8

£•

0.44J

0.39J

M]

0.61J

0.61J

ND(0.10)

ND(0.10)

0.10J

0.076J

ND(0.10)

%±

30.1

34.5

38.1

46.1

32.9

ND(4.0)

ND(4.0)

ND(4.0)

5.8

7.4

Sele

nium

M

6.6

ND(3.5)

2-8J

ND(3.5)

i9J

8.4

ND(3.5)

9.8

9.2

1«

2.6

1.8

1.2

1.7

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

Tha

llium

ND(2.5)

ND(2.5)

3.6

ND(2.5)

ND(2.5)

3.7

6.4

ND(2.5)

4.7

4.7

e211

36.4

40.9

19.8

44.1

40.6

14.7

24.2

ND(5.0)

20.7

16.1

CJ

1

193

222

121J

830J

153J

65.9J

121

11.2

128

105

U•o

Io

ND

(2.5)

ND(2.5)

ND(2.5)

ND(2.5)

ND(2.5)

2.8J

ND(2.5)

ND(2.5)

5.6J

ND(2.5)

Table 3-1June 2004 Low Concentration Soil Sampling Results for Total Metals and Cyanide (mg/kg)

(results significantly above background arebolded and underlined1)

Sample

Location

ZM-S-518

ZM-S-S19

Sample

Date

6/1/04

6/1/04

Location

Description

Sand Dunes

Sand Dunes

Alu

min

um7,410

10,800

>,a

•3

ND

(6.0)

NDM)

'3

1

4.5

4.0

Bar

ium

139

ITS

Ber

ylli

um

ND

(0.50)

ND(0.50)

Cad

miu

m

0.84

1.2

Chr

omiu

m

10.7

13.6

•3.0oU

6.5J

5.6J

S£oO

I8.8J

22.2]

,

50,900

55,900

,

95,8

96.6

f

0.11J

ND(0.10)

u1

6.0

7.9

Sel

eniu

m

8,4

9.1

£«

ND

(1.0)

ND(1.0)

Tha

lliu

m

4.6

4.8

Van

adiu

m

14.9

17.1

(JQ

SI

88.0

107

uT3

1>v

CJ

ND

(2.5)

ND(2.5)

Table 3-1 Notes:

1|D ( > = Analyte not detected above reported sample quantitation limit. The number in parentheses represents the associated quantitation limit.

J = The corresponding result is considered to be estimated due to a high level of uncertainty. Results less than three times the corresponding instrument detection limit arenormally considered to be too low for the measurement process to accurately measure, although it is high enough to establish qualitative presence.

1 = For Hazard Ranking System (HRS) purposes, an analyte is considered to be present at a concentration significantly above background if one of the fcllowing two criteriais met: 1) the analyte is detected in the site-related sample when not detected in the background samples or 2) the analyte is reported at a concentration equal to or greaterthan three tunes the maximum background level when detected in the background samples. In addition, the analytical data must be of known and documented quality.

Data validation results fcr the Zeibright Mine SI sampling data indicate that some of the reported concentrations are qualitatively acceptable but quantitatively questionable.These concentrations were assigned J qualifiers (Appendix H). HRS guidance allows for the use of some types of J-qualified data in documenting the presence of an analyteat a concentration significantly above background. If the bias of a background sample result was low or unknown, the sample concentration was multiplied by thecorresponding Sctor value associated with the analyte being tested. Alternately, if the bias of a source or release sample result was high or unknown, the sampleconcentration was divided by the corresponding fictor value associated with the analyte being tested. Biased sample results that have been assigned J qualifiers hi the tablerepresent concentrations that have been adjusted by the fictor value for the analyte being tested (EPA Quick Reference Fact Sheet, Directive 9285.7-14FS).

PRO Reference:EPA, Region 9 PRO Table, October2004.

Table 3-2June 2004 Low Concentration Sediment Sampling Results for Total Metals and Cyanide (mg/kg)

(results significantly above background are bolded and underlined1)Sample

LocationSample

DateLocation

Description

Alu

min

um

Ant

imon

y

O

1

ea

•gCD B

eryl

lium

Cad

miu

m

Chr

omiu

m

1u

u0.0.OO

Background Samples

ZM-SED-BG1

ZM-SED-BG2

6/2/04

6/2/04

Bear River,up stream of

Zeibright Mine

Bear River,upstream of

Zeibright Mine

15,600

15,900

ND(6.0)

ND(6.0)

10.8

5.6

52.9

63:7

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

22.7

21.2

ND(5.0)

ND(5.0)

19.3

15.8

e£ 1

e>

5

•u•gZ Se

leni

um

?'ffi Th

alliu

m

Van

adiu

m

uR

uT3

1P%U

20,100

17,000

6,8

8.3

ND(0.10)

0.17

15.1

8.9

ND(4.0)

"NO(4.0)

1.5

1.7

ND(3.0)

ND(3.0)

54.5

60.8

45. U

49.8J

3.7

4.3

Source Samples

ZM-SED-S5

ZMSED-S6

6/2/04

6/2/04

Bear River, seep atSand Dunes

Bear River, seep atSand Dunes

7,990

8,290

ND(6.0)

9.7J

5.4

4.0

193

101

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

11.8

10.0

ND(5.0)

ND(5.0)

19.2

10.5

52,400

38,700

«17_

18.9

0.17J

0.094J

18.9

6.9

6,4;

5.9]

ND(1.0)

1.6

9.3

4.2

16.2

27.5

96.6J

4S.2J

ND(1.0)

ND(1.0)

Release Sam pies

ZM-SED-R10

ZM-SED-R9

ZMSED-Rll

(duplicateofZM-

SED*9)

ZM-SED-R8

ZM-SED-R3

6/2/04

6/2/04

6/2/04

6/2/04

6/2/04

Bear River, belowBall Field

Bear River, at SandDunes

Bear River, at SandDunes

Bear River, at SandDunes

Bear River, base ofseep (ZM-SED-S6)

8,630

13,200

10,600

14,300

13,100

L9J

ND(6.0)

ND(6.0)

ND(6.0)

7.SJ

15.1

9.6

5.0

8.5

4.6

34.0

37.6

37.4

57.3

57.1

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(14)

ND(1.0)

ND(1.0)

11.2

14.6

17.2

10.8

11.4

ND(5.0)

ND(5.0)

ND(5.0)

11

ND(5.0)

9.1

13.1

14.8

12.2

13.8

17,600

16,100

14,300

17,000

18,800

5.0

4.2

3.1

5.9

7.9

0.12

0.12

0.11

0.13

0.12

6.3

7.2

7.5

9.3

8.1

ND(4.0)

ND(4.0)

ND(4.0)

ND(4.0)

ND(4.0)

1.2

1.1

1.1

1.3

1.2

ND(3.0)

ND(3.0)

ND(3.0)

ND(3.0)

ND(3.0)

44.9

50.2

43.8

50.3

38.2

25.6J

30.7J

25.3J

42.2J

10.8J

2.9

2.9

ND(1.0)

3.2

ND(1.0)

Table 3-2June 2004 Low Concentration Sediment Sampling Results for Total Metals and Cyanide (mg/kg)

(results significantly above background are bolded and underlined1)

SampleLocation

ZMSED-Rl

ZM-SED-R2

ZM-SED-R5

ZMSED-R6

(duplicateofZM-

SED-R5)

SampleDate

6/2/04

6/2/04

6/2/04

6/2/04

LocationDescription

Bear River,downstream of mine

tailings

Bear River,downstream of mine

tailings

Rollins Reservoir

Rollins Reservoir

|a

6,050

11,400

20,500

13,600

Ant

imon

y

8.2J

ND(6.0)

ND(6.0)

MJ

.a51

ND(1.0)

4.2

7.1

8.0

Bar

ium

113

54.7

182

124B

eryl

lium

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

Cad

miu

m

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

Chr

omiu

m

4.9

17.5

23.9

18.9

3a0U

ND(5.0)

£6

11.7

12

I1u

7.7

11.4

.44.2

42.1

I

30,700

20,100

29,000

23,000

,

35.1

6.8

11.6

10.4

&

0.14J

0.12

ND(0.10)

ND(0.10)

|'1

ND(4.0)

10.7

29.8

24.3

|

1u

VI

ND(4.0)

ND(4.0)

5.1J

ND(4.0)

b

55

1.4

1.1

1.4

1.4

Thal

lium

ND(3.0)

ND(3.0)

ND(3.0)

ND(3.0)

Van

adiu

m

11.8

43.3

50.8

46.9

U

N

47.4J

44.2J

138J

120J

U•o

1>,u

ND(1.0)

2.9

3.6

3.5

Table 3-2 Notes:

J = The corresponding result is considered to be estimated due to a high level of uncertainty. Results less than three times the corresponding instrument detection limit arenormally considered to be too low for the measurement process to accurately measure, although it is high enough to establish qualitative presence.

1 = For Hazard Ranking System (HRS) purposes, an analyte is considered to be present at a concentration significantly above background if one of the following two criteriais met: 1) the analyte is detected in the site-related sample when not detected in the background samples or 2) the analyte is reported at a concentration equal to or greaterthan three times the maximum background level when detected in the background samples. In addition, the analytical data must be of known and documented quality.

Data validation results for the Zeibright Mine SI sampling data indicate that some of the reported concentrations are qualitatively acceptable but quantitatively questionable.These concentrations were assigned J qualifiers (Appendix H). HRS guidance allows for the use of some types of J-qualified data in documenting the presence of an analyteat a concentration significantly above background. If the bias of a background sample result was low or unknown, the sample concentration was multiplied by thecorresponding fector value associated with the analyte being tested. Alternately, if the bias of a source or release sample result was high or unknown, the sampleconcentration was divided by the corresponding fector value associated with the analyte being tested. Biased sample results that have been assigned J qualifiers in the tablerepresent concentrations that have been adjusted by the lactor value for the analyte being tested (EPA Quick Reference Fact Sheet, Directive 9285.7-14FS).

Table 3-3June 2004 Low Concentration Surface Water Sampling Results for Total Metals and Cyanide (|a g/L)

(results significantly above background are bolded and underlined1)Sample

LocationSample

DateLocation

Description

Ant

imon

y

Ars

enic

Bar

ium

Bei

ylli

um

Cad

miu

m

Chr

omiu

m

•̂§u

SCL.a.ou

•o3£•§S

"(5jrfo2

Background Samples

ZKfrSW-BG1

ZMSW-BG2

6/2/04

6/2/04

!M-SW-S5

2MSW-S6

6/2/04

6/2/04

Bear River,upstream of

Bear River,upstream of

Zeibright Mine

3.3

2.9

1.8J

1.6J

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(2.0)

ND(2.0)

1.2

1.2

ND(2.0)

6.7

ND(1.0)

NDG.O)

ND(0.20)

ND(0.20)

ND(1.0)

ND(1.0)

Sele

nium

Sij»'Vi IT

ialli

um

Van

adiu

m

U

«

•S1>,u

ND(5.0)

ND(5.0)

ND

0.0)

ND(1.0)

ND(1.0)

ND

0-0)

ND(1.0)

ND(1.0)

ND(2.0)

ND(2.0)

ND00.0)

ND00.0)

Source Samples

Bear River, seep atSand Dunes

Bear River, seep atSand Dunes

3.1

3.0

ND

(1.0)

ND(1.0)

US

10.4

ND

(1.0)

ND(1.0)

ND(1.0)

ND

(1.0)

ND(2.0)

ND(2.0)

ND(1.0)

1.3

ND(2.0)

ND

(2.0)

ND(1.0)

ND(1.0)

ND(0.20)

ND(0.20)

1.2

LL

ND(5.0)

ND(5.0)

ND(1.0)

ND(1.0)

ND

0-0)

ND(1.0)

ND

0.0)

ND(1.0)

iii

4.0

ND(10.0)

ND(10.0)

Release Sam pies

ZM-SW-R10

ZMSW-R9

ZM-SW-Rll

(duplicateofZM-SW-R9)

ZM-SW-R8

ZM-SW-R3

6/2/04

6/2/04

6/2/04

6/2/04

6/2/04

Bear River, belowBall Field

Bear River, at SandDunes

Bear River, at SandDunes

Bear River, at SandDunes

Bear River, base ofseep (ZM-SED-S6)

2.7

2.7

3.0

3.2

2.7

l.U

ND(1.0)

ND(1.0)

1.4J

1.2J

ND(1.0)

24.7

28.5

ND(1.0)

IS,!

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND

(1.0)

ND(1.0)

ND

(1.0)

ND(1.0)

ND(1.0)

ND(2.0)

ND

(2.0)

ND(2.0)

ND(2.0)

ND(2.0)

1.1

M

11.0

1.0

1.2

ND(2.0)

5.1

4.7

NDC2.0)

ND(2.0)

ND(1.0)

1.63

L2J

ND(1.0)

0.050J

ND(0.20)

ND(0.20)

ND(0.20)

ND(0.20)

ND(0.20)

ND(1.0)

22.1

2T7

ND

(1-0)

ND(1.0)

ND(5.0)

ND(5.0)

ND(5.0)

ND(5.0)

ND(5.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND(1.0)

ND

0.0)

ND(1.0)

ND

0.0)

ND(1.0)

ND

0.0)

ND(1.0)

ND

G.O)

ND(1.0)

ND(1.0)

ND

(1.0)

ND

(1.0)

LI

S4A

56.0

5.6

2.5

ND(10.0)

ND(10.0)

ND(10.0)

ND

(10.0)

ND(10.0)

Table 3-3June 2004 Low Concentration Surface Water Sampling Results for Total Metals and Cyanide Oig/L)

(results significantly above background are bolded and underlined1)Sample

Location

2MSW-Rl

ZMSW-R2

ZMSW-R5

SampleDate

6/2/04

6/2/04

6/2/04

LocationDescription

Bear River,downstream of mine

tailings

Bear River,downstream of mine

tailings

Rollins Reservoir

>.e

•nn<

2.9

3.2

3.1

.|

I.1J

ND(1.0)

ND(1.0)

S

1at

ND(1.0)

ND(1.0)

14.1

S

1a

ND(1.0)

ND(1.0)

ND(1.0)

Cad

miu

m

ND

(1.0)

ND(1.0)

ND(1.0)

Chr

omiu

m

ND(2.0)

ND(2.0)

ND(2.0)

.̂a0U

ND(1.0)

ND(1.0)

1.1

OJO.g-o

ND(2.0)

ND

(2.0)

ND(2.0)

•a3

ND0.0)

ND(1.0)

ND(1.0)

t̂!3

ND(0.20)

ND(0.20)

ND(0.20)

*«

•gz

ND(1.0)

ND(1.0)

Li

Sele

nium

ND(5.0)

ND(5.0)

ND(5.0)

j>to

ND(1.0)

ND(1.0)

ND(1.0)

Tha

lliu

m

ND

(1.0)

ND(1.0)

ND(1.0)

£3

i

ND(1.0)

ND(1.0)

ND

(1.0)

ocN

11

11

iM

4>•o'i>,u

ND(10.0)

ND(10.0)

ND(10.0)

Table 3-3 Notes:

ND ( ) = Analyte not detected above reported sample quantitation limit. The number in parentheses represents the associated quantitation limit.

J=The corresponding result is considered to be estimated due to a high level ofuncertainty. Results less than three times the corresponding instrument detection limit are normallyconsidered to be too low for the measurement process to accurately measure, although it is high enough to establish qualitative presence.

1 = For Hazard Ranking System (HRS) purposes, an analyte is considered to be present at a concentration significantly above background if one of the following two criteriais met: 1) the analyte is detected in the site-related sample when not detected in the background samples or 2) the analyte is reported at a concentration equal to or greaterthan three times the maximum background level when detected in the background samples. In addition, the analytical data must be of known and documented quality.

Data validation results for the Zeibright Mine SI sampling data indicate that some of the reported concentrations are qualitatively acceptable but quantitatively questionable.These concentrations were assigned J qualifiers (Appendix H). HRS guidance allows for the use of some types of J-qualified data hi documenting the presence of an analyteat a concentration significantly above background. If the bias of a background sample result was low or unknown, the sample concentration was multiplied by thecorresponding fictor value associated with the analyte being tested. Alternately, if the bias of a source or release sample result was high or unknown, the sampleconcentration was divided by the corresponding factor value associated with the analyte being tested. Biased sample results that have been assigned J qualifiers in the tablerepresent concentrations that have been adjusted by the fector value for the analyte being tested (EPA Quick Reference Fact Sheet, Directive 9285.7-14FS).

Table 3-4June 2004 Low Concentration Groundwater Sampling Results for Total Metals and Cyanide (tig/L)

(results above current MCLs are bolded and underlined)

SampleLocation

SampleDate

LocationDescription

Maximum Contaminant Level (MCL)

ZMCW.Rl

2M-GW-R2

6/2/04

6/2/04

On -site drinkingwater well

(WELL01)

On-site drinkingwater well

(WELL01)

Ant

imon

y

6.0

3.0

2.9

o'e£<

10

ND(1.0)

ND(1.0)

e1m

2,000

ND(1.0)

ND(1.0)

E

^frm

4.0

ND(1.0)

ND(1.0)

Cad

miu

m

5.0

ND(1.0)

ND(1.0)

Chr

omiu

m

100

ND(2.0)

ND(2.0)

•a•§u

NR

1.0

ND(1.0)

4>OiQ.OU

1,300

ND(2.0)

2.3

J

15

ND(1.0)

ND(1.0)

£•

2.0

ND(0.20)

ND(0.20)

V

|

NR

1.1

1.3

Sele

nium

50

ND(5.0)

ND(5.0)

S

i/5

NR

ND

0.0)

ND(1.0)

Tha

llium

2.0

ND(1.0)

ND(1.0)

Van

adiu

m

NR

ND(1.0)

ND

(1.0)

SN

NR

12.5

12.1

4>"O

'i>>u

200

ND(10.0)

ND(10.0)

Table 3-4 Notes:

ND ( ) = Analyte not detected above reported sample quantitation limit. The number in parentheses represents the associated quantitation limit.

NR = Not Reported in the United States Environmental Protection Agency (EPA), Office of Emergency and Remedial Response, Superfund Chemical Data Matrix (January

2004) or on the EPA website.

J = The corresponding result is considered to be estimated due to a high level of uncertainty. Results less than three tunes the corresponding instrument detection limit are

normally considered to be too low for the measurement process to accurately measure, although it is high enough to establish qualitative presence.