Human Health and Ecological Risk Assessment Granite Creek Mines Wallowa Whitman National Forest

Transcription

1 Wallwa Whitman Natinal Frest April 2006 Cascade Earth Sciences P.O. BOX Spkane, Washingtn (509)

2 Wallwa Whitman Natinal Frest Principal Authr and Investigatr: Rne Brewer, Senir Eclgist Regina Skarzinskas, Senir Txiclgist Ryan Tbias, Staff Bilgist Dustin G. Wasley, PE, Managing Engineer II Reviewed By: Jhn D. Martin, R.G., Principal Gelgist Prepared fr: USDA Frest Service Wallwa-Whitman Natinal Frest Site Lcatin: Wallwa Whitman Natinal Frest Grant Cunty, Oregn Prepared by: Cascade Earth Sciences P.O. Bx Spkane, Washingtn (509) April 2006 Cver Pht: Mnumental Mine Millsite.

3 TABLE OF CONTENTS EXECUTIVE SUMMARY...iv 1.0 INTRODUCTION RISK ASSESSMENT DATA AND INITIAL SCREENING HUMAN HEALTH RISK ASSESSMENT HAZARD IDENTIFICATION AND SELECTION OF COPCS EXPOSURE ASSESSMENT TOXICITY ASSESSMENT RISK CHARACTERIZATION CALCULATION OF CLEANUP GOALS DETERMINATION OF POTENTIAL HOT SPOTS SUMMARY OF HUMAN HEALTH RISKS ECOLOGICAL RISK ASSESSMENT PROBLEM FORMULATION ECOLOGICAL RISK-BASED SCREENING ECOLOGICAL RISK CHARACTERIZATION SUMMARY OF ECOLOGICAL RISKS CONCLUSIONS RECOMMENDATIONS REFERENCES...25 FIGURES FIGURE 3-1: FIGURE 4-1: Cnceptual Human Health Expsure Mdel Cnceptual Eclgical Expsure Mdel APPENDICES APPENDIX A: APPENDIX B: APPENDIX C: APPENDIX D: Initial Screening Results (USFS Prject File) Human Health Risk Calculatins (USFS Prject File) Eclgical Scping Checklist (USFS Prject File) Eclgical Risk-Based Screening Tables (USFS Prject File) ACRONYMS CEEM COI COPC COPEC ODEQ ERA ERBSC HHRA PRG SI RTE 90UCL USEPA USFS WWNF cnceptual eclgical expsure mdel chemical f interest chemical f ptential cncern chemical f ptential eclgical cncern Oregn Department f Envirnmental Quality eclgical risk assessment eclgical risk-based screening cncentratin human health risk assessment Preliminary Remediatin Gals Site Inspectin rare, threatened, r endangered 90 th percentile upper cnfidence limit n the arithmetic mean United States Envirnmental Prtectin Agency United States Department f Agriculture, Frest Service Wallwa Whitman Natinal Frest Dc: Final Risk Assessment April 2006 / Page iii

4 EXECUTIVE SUMMARY Ptential human health and eclgical risks assciated with mining-related cntaminatin at the Mnumental, Cap Martin, Sheridan, Tillicum, and Central Mines (cllectively referred t as the ) within the Granite Creek watershed (Site) were assessed thrugh a streamlined risk assessment prcess. The Site is lcated in the upper prtin f the Granite Creek watershed, 5 t 8 miles nrth f Granite, Oregn in Grant Cunty in the Wallwa Whitman Natinal Frest. The risk assessment prcess generally fllws U.S. Envirnmental Prtectin Agency and Oregn Department f Envirnmental Quality guidelines. The fllwing is a summary f the human health risk assessment: Current and future ptential receptrs were identified as hunters, hikers, and campers. Arsenic and lead were identified as the sil/wasterck, sediment, and surface water nncarcingenic cntaminants f ptential cncern (COPCs). N unacceptable nn-carcingenic health effects are anticipated under bth the central tendency expsure (CTE) and reasnable maximum expsure (RME) cnditins. Arsenic was the nly carcingenic COPC identified at the Site. Carcingenic risks were predicted frm expsure t arsenic-impacted surface water and sil/wasterck under bth the CTE and the RME expsure cnditins. N carcingenic risks were predicted frm expsure t sediment. N ht spts were identified at the Site. The fllwing is a summary f the eclgical risk assessment Eclgical impacts were predicted fr immbile species, primarily plants and terrestrial invertebrates, due t cntaminants f ptential eclgical cncern (COPECs) in sil and wasterck. Lcal and reginal ppulatins f these and ther terrestrial species are unlikely t be significantly impacted. Eclgical impacts were als predicted fr aquatic life and wildlife expsed t COPECs in surface water and pre water. Hwever, the lack f backgrund samples makes it mre difficult t predict the ptential fr impacts. Benthic invertebrates and wildlife appear t have the ptential t be impacted by ttal arsenic, cadmium, and zinc, which are present at elevated cncentratins at nearly all sediment sample lcatins. The lack f backgrund sediment samples likely results in an verestimatin f these ptential impacts. The Mnumental and Tillicum Mines appear t have mre lcatins with elevated COPEC cncentratins in sil/wasterck than the ther mines. Multiple eclgical ht spts were identified at nearly every mine. Based n the infrmatin presented in this reprt, CES recmmends: Perfrming an Engineering Evaluatin / Cst Analysis (EECA) fr the fllwing reasns: Unacceptable carcingenic risks were predicted frm expsure t arsenic in wasterck under the CTE and RME recreatinal expsure scenaris. Eclgical risks were predicted frm expsure t multiple COPECs in all media. Multiple eclgical ht spts were identified in all media. In additin, as part f the EECA, a data gap investigatin shuld be cmpleted t address multiple data gaps identified at the Site. Dc: Final Risk Assessment April 2006 / Page iv

5 1.0 INTRODUCTION Ptential human health and eclgical risks assciated with mining-related cntaminatin at the Mnumental, Cap Martin, Sheridan, Tillicum, and Central Mines (cllectively referred t as the ) within the Granite Creek watershed (Site) were assessed thrugh a streamlined risk assessment prcess. The Site is lcated in the upper prtin f the Granite Creek watershed, 5 t 8 miles nrth f Granite, Oregn in Grant Cunty in the Wallwa Whitman Natinal Frest (WWNF). The risk assessment prcess fllws Oregn Department f Envirnmental Quality (ODEQ) and U.S. Envirnmental Prtectin Agency (USEPA) guidelines. Ptential risks and hazards were evaluated using Site-specific cncentratins f chemicals f interest (COIs), selected human and eclgical receptrs and respective expsure pathways, and apprpriate risk-based screening cncentratins. 2.0 RISK ASSESSMENT DATA AND INITIAL SCREENING This sectin describes the data set used in this risk analysis and the initial screening fr the human health risk assessment (HHRA) and eclgical risk assessment (ERA). Data were selectively cllected in areas where cntaminatin was knwn r suspected t ccur; therefre, the data set is skewed twards an understanding f the magnitude f cntaminatin n Site rather than a full characterizatin f the Site. The data used in the risk assessment are frm sil, vegetatin, wasterck, surface water, pre water, and sediment samples cllected during the Site Inspectin (SI) cnducted by EA Engineering, Science, and Technlgy, Inc. (EA) in January 2004 (EA, 2004). The fllwing samples were cllected frm five mines within the watershed: 4 backgrund sil samples 24 surface and subsurface wasterck samples 14 surface sil samples fr the HHRA at feet belw the grund surface [bgs] 17 surface sil samples fr the ERA at 0-3 feet bgs, and 10 subsurface sil samples at greater than 1.5 feet bgs fr the HHRA. 4 backgrund vegetatin samples 6 vegetatin samples 13 surface water samples 11 pre water samples 20 sediment samples Overall, the data are likely t verestimate the cncentratins fund acrss the Site because samples were lcated t represent the areas f highest COI cncentratins, nt areas representative f verall human and eclgical receptr expsure at and surrunding the Site. This is a cnservative apprach that is apprpriate fr screening level risk assessments. Initially, all data cllected during the SI and deemed apprpriate fr use in the risk assessment were used t calculate the 90 th percentile upper cnfidence level n the arithmetic mean (90UCL) fr each medium: The 90UCL is an upper-bund (i.e., cnservative) estimate f mean chemical cncentratin and is specified as an apprpriate expsure pint cncentratin (EPC) in Oregn s Revised Cleanup Rules (OAR ). If fewer than 10 samples are available in a given medium, it is inapprpriate t calculate a 90UCL (USEPA, 2003). In these cases, and if an apprpriately calculated 90UCL exceeded the maximum detected cncentratin, the maximum detected cncentratins were used as a substitute fr the 90UCL. Dc: Final Risk Assessment April 2006 / Page 1

6 The data were screened using the ODEQ s Guidance fr Cnduct f Deterministic Risk Assessments (1998), which allws fr prescreening f COIs based n the fllwing criteria: Essential Nutrients: calcium, magnesium, ptassium, and sdium were remved frm further assessment because they are cnsidered t be essential nutrients. Frequency f Detectin: COIs in each medium that were detected in 5% r less f the samples Site-wide were remved frm further assessment. Backgrund: 90UCL r maximum (as described abve) cncentratins f naturallyccurring chemicals that were present at cncentratins less than maximum backgrund cncentratins were eliminated frm further assessment. The results f these initial screening prcedures fr each ptential expsure medium are als shwn in Tables A-1 thrugh A-7 in Appendix A. The tables in Appendix A depict sample reprting limit screening that shws which undetected chemicals have reprting limits that are belw backgrund cncentratins and belw the lwest applicable medium-specific risk-based screening cncentratins. If a chemical did nt meet this criterin, the COI was cnservatively included fr further assessment at ne-half the maximum sample reprting limit. The selected COIs fr the HHRA and ERA are shwn in Table 2-1. Table 2-1 Chemicals f Interest Remaining Fllwing the Initial Screening COIs Sil/ Waste Material Vegetatin Surface Water Pre Water Sediment HHRA ERA ERA HHRA ERA ERA HHRA ERA Aluminum X X X X X Antimny X X X X Arsenic, ttal X X X X X X X X Barium X X X X X X X Beryllium X X X Cadmium X X X X X Chrmium, ttal X X X X X Cbalt X X Cpper X X X X X Irn X X X X X X X X Lead X X X X X X X X Manganese X X X X X X X Mercury X X X X X X X X Nickel X X Selenium X X X X X X X Silver X X X X X X Thallium X X X X X X Vanadium X X X X X Zinc X X X X X X X X X = COI selected fr further screening 3.0 HUMAN HEALTH RISK ASSESSMENT A HHRA is an analysis f the ptential adverse health effects that culd result frm current r future expsures t hazardus substances released frm a site, in the absence f any actin t cntrl r mitigate these releases. Dc: Final Risk Assessment April 2006 / Page 2

7 The bjective f this HHRA is t incrprate analytical data and infrmatin n ptential human expsure t the COIs in rder t prvide a baseline assessment f the ptential fr human health risks t be realized due t Site-related cntaminatin. The fllwing are primary elements f the HHRA: Hazard Identificatin and Selectin f Cntaminants f Ptential Cncern: Evaluatin f Site data and identificatin f elevated cncentratins f COIs in human expsure media, resulting in a list f cntaminants f ptential cncern (COPCs) fr the HHRA. Expsure assessment: Identificatin f areas that pse human health risks under current r ptential future site uses and cnservative estimatin f expsure. Txicity assessment: Quantificatin f the relatinship between chemical expsure and adverse effects. Risk characterizatin: Develpment f quantitative risk estimates using expsure and txicity infrmatin previusly develped fr the COPCs. 3.1 HAZARD IDENTIFICATION AND SELECTION OF COPCS This sectin presents the ratinale fr the selectin f the COPCs. Prescreening f the COIs was described in Sectin 2.0. The media f interest fr human health included sil, wasterck, surface water, and sediment. Thse COIs that were retained fr further assessment fllwing the initial screening are shwn in the last clumn f Tables A-1, A-2, A-4, and A-6 fr surface sil, subsurface sil, surface water (including ne adit water sample), and sediment, respectively. Maximum cncentratins f these COIs were screened against USEPA Regin IX Preliminary Remediatin Gals (PRGs). Industrial PRGs were selected as mst apprpriate screening criteria fr sils and sediment. Tap water PRGs represent a very cnservative screen fr surface water. Table B-1 present the PRG screening and results. Arsenic and lead were identified as COPCs fr the Site. 3.2 EXPOSURE ASSESSMENT Assessing the expsure at a given site includes the identificatin f ptentially expsed ppulatins, the selectin f relevant expsure pathways, and the calculatin f expsure pint cncentratins and chrnic daily intakes Ptentially Expsed Ppulatin The Site cnsists f five mines lcated within the Granite Creek watershed. Maps and figures f the Site are prvided in the SI reprt (EA, 2004). The fllwing is a brief summary f the ratinal fr the ptentially expsed ppulatin: Mnumental Mine The Mnumental Mine, lcated near the headwaters f Granite Creek, includes tw pen adits, a shaft, three settling pnds, three wasterck piles, and a frmer mill site. Access t the mine is by way f FR The mine is situated n mderate t steep hillsides at the headwaters f Granite Creek. Water flws frm an upper seep int a series f three settling pnds, all f which are cnnected by surface water flw. In additin, water seeps frm the lwer adit thrugh a cnstructed ditch t the lwer settling pnd. N utlet fr the settling pnd was bserved during SI activities. Dc: Final Risk Assessment April 2006 / Page 3

8 Cap Martin Mine The Cap Martin Mine is situated apprximately 1.4 miles dwnstream frm the headwaters f Granite Creek and cntains tw bserved cllapsed adits, ne additinal reprted adit, three wasterck piles, and an utwash fan frm the suth wasterck pile. The mine is lcated n mderately steep hillsides n bth sides f Granite Creek and is accessed via FR Sheridan Mine The Sheridan Mine is lcated abut 0.40 miles dwnstream f the Cap Martin Mine, east f the bank f an unnamed tributary f Granite Creek. The mine includes tw pssible adits, ne f which is cllapsed at the prtal and cntains a seep that discharges int a marshy area. One wasterck pile is lcated dwngradient frm the cllapsed adit. The mine is situated n mderately steep slpes n the suth side f Granite Creek and is accessed via FR Tillicum Mine The Tillicum Mine is lcated alng Granite Creek, apprximately 0.25 miles dwnstream f the Sheridan Mine and cntains tw cllapsed adits and assciated wasterck piles, and reprtedly several additinal adits. N water was bserved flwing frm the adits during SI field activities. The mine is situated n mderately steep slpes alng the nrth bank f Granite Creek and is accessed via FR Central Mine The Central Mine is lcated abut 0.6 miles dwnstream f the Tillicum Mine, sutheast f the intersectin f FR 73 (Elkhrn Drive Scenic Byway) and FR The mine cntains tw bserved adits and ne reprted adit; water was nt bserved flwing frm the adits during the SI field investigatin. Three wasterck piles are lcated at the mine. A wasterck berm, created as a result f hydraulic mining activities, runs in east-west directin abut 75 t 100 feet upslpe f Granite Creek. The mine is situated n a mderately steep slpe nrth f Granite Creek. Given the types f human uses expected, the ptential fr lng-term expsure t Site-related cntaminants is cnsidered lw. There are n nsite wrkers, r ccupied structures, n the Site r within 200 feet f the Site. Access is currently nt restricted by fencing, nr were any N Trespassing signs bserved. In general, land uses in this area are limited t recreatin (hiking, fishing, camping, hunting, etc.) and pssibly sme minerals prspecting n nearby claims. The ingestin, dermal cntact, and air expsure pathways are cnsidered cmplete, because hikers, hunters, and campers have the ptential t access the Site. The mst likely pathway f expsure at the Site is inhalatin f particulates. Fish cnsumptin was eliminated as a ptential pathway f cncern because, with the exceptin f tribal fishing, all recreatinal fishing in Granite Creek and its tributaries was prhibited by the Oregn Department f Fish and Wildlife (ODFW) in 1997 (EA, 2004). The number and size f fish present als severely limits any ptential fr a recreatinal r subsistence fishing scenari. Dc: Final Risk Assessment April 2006 / Page 4

9 3.2.2 Identificatin f Ptential Expsure Pathways The cnceptual human expsure mdel is presented in Figure 3-1. Expsures t COPCs were evaluated fr all cmplete pathways fr which there was a receptr. These pathways were determined t be: Inhalatin f sil/wasterck particulates; Dermal cntact with surface water, sediment, and sil/wasterck; and Incidental ingestin f surface water, sediment, and sil/wasterck Current and Ptential Future Receptrs The Site is nt currently ccupied, nr is it expected t be ccupied in the future. The nly likely current and future receptrs are hikers, campers, and hunters Expsure Assumptins Expsure assumptins include factrs such as bdy weight, averaging time, expsure frequency, expsure duratin, and chemical biavailability. Separate assumptins are made fr bth average r central tendency expsure (CTE) and reasnable maximum expsure (RME). In general, CTE represents a less cnservative mdel f the Site risk, using expsure factrs that are mre indicative f the average recreatinal user rather than a maximally expsed user. The expsure factrs and assumptins used in this risk assessment are presented in Table B-2 in Appendix B Expsure Pint Cncentratins An EPC is used in crdinatin with the expsure factrs t calculate the Average Daily Dse (ADD) f a COPC. The EPC can be the maximum cncentratin detected r a statistical average. It is nt reasnable t assume lng-term cntact with the maximum cncentratin. When sufficient data exists, an upper-bund estimate f average cncentratins (i.e., the 90UCL) is used because an average cncentratin is mst representative f the cncentratin cntacted ver this time perid. As per the USEPA (1997), when data fr a particular expsure medium were limited t less than 10 samples, the maximum detected cncentratin was used as the EPC. Where the data set cntained greater than 10 samples, 90UCL was calculated and used as the EPC. The EPCs are presented in Table 3-1 and Table B-3 in Appendix B. Dc: Final Risk Assessment April 2006 / Page 5

10 Table 3-1 Expsure Pint Cncentratins Central COPC N Maximum Tendency Expsure 1 Surface Sil (milligrams per kilgram[mg/kg]) Reasnable Maximum Expsure 2 Cmments Ttal Arsenic UCL Sediment (mg/kg) Ttal Arsenic UCL Surface Water (milligrams per liter [mg/l]) Ttal Arsenic UCL 1 Average cncentratin 2 90UCL if greater then 10 datapints; Maximum cncentratin if less than 10 datapints n = Number f samples EPC = Expsure pint cncentratin UCL = Upper cnfidence Limit Expsure Dses The EPCs are then entered int expsure dse calculatins t calculate the ADD f a cntaminant fr each receptr type. While presented individually in the equatins, USEPA Regin X allws fr the calculatin f Summary Intake Factrs (Intake Factrs) as fllws: Intake Factrs represent the sum lifetime expsure t cntaminated sil, water, r air thrugh the pathway. The Intake Factrs are presented in Table B-4. Dermal absrptin factrs are required t calculate dermal expsures t surface water and these are shwn in Tables B-5 and B-6. The Intake Factrs, when multiplied by the EPC, prvide the ADD fr each chemical. 3.3 TOXICITY ASSESSMENT The purpse f the txicity assessment is t present the critical txicity values fr the COPCs. Txicity is defined as the ability f a chemical t induce adverse effects at sme dsage in bilgical systems. The purpse f the txicity assessment is twfld: T identify the carcingenic (cancer) and nn-carcingenic (nn-cancer) effects that may arise frm direct r indirect expsure f humans t the COPCs; and T prvide an estimate f the quantitative relatinship between the magnitude and duratin f expsure, and the prbability r severity f adverse effects Txicity Values Txicity values are used t quantitatively describe the relatinship between the extent f expsure t a COPC and the ptential increased likelihd, r severity, f adverse effects. Where txicity values are available, the fllwing surces have been used: Integrated Risk Infrmatin System (IRIS) cmputer database (USEPA, 2004) Health Effects Assessment Summary Table (HEAST) (USEPA, 1997) Dc: Final Risk Assessment April 2006 / Page 6

11 Bth carcingenic and nn-carcingenic effects were quantitatively evaluated as nted belw: The endpints fr these tw different types f effects are assessed differently because the mechanisms by which chemicals cause cancer are assumed t be fundamentally different frm the prcesses that cause nn-carcingenic effects. The principal difference reflects the assumptin that nn-carcingenic effects are assumed t exhibit a threshld dse belw which n adverse effects ccur, where USEPA assumes n such threshld exists fr carcingenic effects. Because expsure t sme chemicals may result in bth carcingenic and nn-carcingenic effects, bth endpints assciated with a COPC were evaluated quantitatively when sufficient txicity data are available Categrizatin f Chemicals as Nn-Carcingens r Carcingen Chemicals are classified as thse that cause cancer (carcingens) and thse that cause ther, nncancer, health effects (nn-carcingens). The methds fr assessing the ptential fr these tw different types f health effects are different. Where a chemical can cause cancer and nn-cancer health effects, the risk evaluatin calculates the ptential fr bth types f effects. The fllwing sectins prvide backgrund infrmatin n the txicity values fr carcingenic and nn-carcingenic chemicals, hw they are determined, and hw they are used in the risk analysis Ptential Adverse Nn-carcingenic Health Effect The fllwing summarizes the purpse and usage f reference dses (RfDs): Reference dses are critical txicity factrs fr chemicals that can cause nn-carcingenic health effects. An RfD represents an estimated intake rate that is unlikely t prduce measurable adverse effects ver a lifetime f expsure (USEPA, 1989a). RfDs are determined by the USEPA RfD Wrk Grup r frm the health effects assessment dcuments develped by the USEPA Office f Research and Develpment. An RfD, expressed in units f milligrams per kilgram per day (mg/kg-day), assumes a threshld fr adverse nn-carcingenic effects. An ADD belw the RfD is cnsidered unlikely t cause adverse health effects. RfDs are rute-specific; that is, RfDs may be different fr ingestin, inhalatin, r ther rutes f expsure. RfDs are derived using uncertainty factrs (UFs) and mdifying factrs (MFs). The Critical Txicity Factrs fr the nn-carcingenic COPCs are presented in Table 3-2 and B-7 in Appendix B. COPC Table 3-2 Critical Txicity Values fr the Nn-carcingenic COPCs Oral Cnfidence Chrnic Endpint in Reference Reference Dse* Dse (mg/kg-day) Arsenic Medium hyperpigmentatin, vascular * Reference Dse value frm Regin IX PRG Tables Dc: Final Risk Assessment April 2006 / Page 7

12 Ptential Carcingenic Effects Carcingenic txicity is nt assumed t have a threshld cncentratin belw which adverse effects d nt ccur; therefre, carcingenic risk frm expsure t a COPC is expressed in terms f the prbability that an expsed receptr will develp cancer ver their lifetime. Cntaminant-specific dse respnse curves are used t establish slpe factrs (SFs) that represent an upper-bund excess cancer risk frm a lifetime expsure. Dse respnse curves fr human carcingens are develped frm tumrgenic and labratry studies; the SF is generated frm the 90UCL f the extraplated dse curve using prbabilistic methds and represents a cnservative upper-bund estimate f the ptential risk assciated with expsure. Based n USEPA guideline dcuments, critical txicity data fr arsenic and chrmium are presented in Table 3-3 and B-8 in Appendix B (refer t USEPA 1999 fr additinal infrmatin). Table 3-3 Critical Txicity Values fr the Carcingenic COPCs Slpe Factr Weight f Evidence Type f Basis f (mg/kg/day)-1 Classificatin* cancer Slpe Factr COPC Ingestin/ Oral Inhalatin Ingestin/Inhalatin Inhalatin Oral/Inhalatin Arsenic 1.5E E+01 A Skin Epidemilgic Studies A = Knwn human carcingen Lead Critical Txicity Values Meaningful ral and inhalatin critical txicity values have nt been develped fr lead. Many f the nn-carcingenic effects assciated with lead may nt exhibit a threshld, especially in yung children. USEPA cnsiders lead t be a B2 carcingen. In lieu f a reference dse r slpe factr, USEPA has develped the Integrated Expsure Uptake/Bikinetic Mdel (IEUBK) and the Adult Lead Mdel (ALM) which crrelate dse with bld lead levels. The Federal Actin Level fr Lead in drinking water is mg/l (USEPA, 2002). Lead expsure levels are as fllws: The lwest-bserved adverse effect level (LOAEL) f lead is cnsidered t be 10 micrgrams per deciliter (µg/dl) in children and fetuses and 30 µg/dl in adults. Empirically-derived ratis f 0.16 and 0.04 µg/dl per µg/day ingested by children and adults respectively, recmmended by USEPA (1986) are used t predict cncentratins in yung children and adults. Applying an uncertainty factr f 10 results in prvisinal tlerable intake levels f 6 µg/day fr children six r less, 15 µg/day fr children ver six, 25 µg/day fr pregnant wmen and 75 µg/day fr men. 3.4 RISK CHARACTERIZATION Ptential human health impacts assciated with expsure t COPCs at the Site were evaluated by estimating the ptential fr bth nn-carcingenic and carcingenic health effects. The fllwing sectins discuss the assessment f nn-carcingenic hazards, carcingenic risks, and lead risk assciated with expsure t COPCs at the Site. Dc: Final Risk Assessment April 2006 / Page 8

13 The sampling lcatins were selected as lcatins where levels f cncentratins were suspected t be the highest. This type f sampling identifies the wrst-case situatins and is intended t be a cnservative data set that is sufficient fr the specific purpses f risk assessment Nn-Carcingenic Hazard Assessment Nn-carcingenic hazard is estimated as the rati f the ADD f the nn-carcingenic chemical thrugh a specific expsure rute t the chrnic (r subchrnic) RfD fr that expsure rute. Fr example, intakes frm the ingestin rute are cmpared t ral RfDs. The assessment is cmpleted as fllws: The ADD divided by the RfD fr an individual chemical is termed the Hazard Qutient (HQ). HQs greater than 1.0 indicate the ptential fr adverse health effects because the intake exceeds the RfD (USEPA, 1986b). An HQ is calculated fr each chemical that elicits a nn-carcingenic health effect if an RfD is available fr the chemical and expsure rute. The sum f all individual chemical-specific HQs is termed the Hazard Index (HI) and is calculated under each expsure pathway. The HI cnsiders expsure t a mixture f chemicals having nn-carcingenic effects based n the assumptin that the effects f chemical mixtures are additive (USEPA, 1986b). An HI greater than 1.0 indicates the ptential fr adverse nn-carcingenic effects. When the HI is greater than 1.0, the USEPA guidance allws fr segregating HIs by critical effect categries. Majr categries f critical effects include neurtxicity, develpmental effects, and effects n target rgans t name a few Excess Cancer Risk Assessment Carcingenic risk is an estimate f the prbability that a COPC will prduce a carcingenic effect. The excess lifetime carcingenic risk is the incremental increase in the prbability f develping cancer cmpared t the backgrund incremental prbability f develping cancer with n expsure t Site cntaminants. An excess cancer risk (ECR) f 1 x 10-6, represents an increase f ne additinal case f cancer (abve backgrund) in ne millin peple expsed t a carcingen ver their lifetime (70 years). Estimates f carcingenic risk using the slpe factrs develped by USEPA are generally upperbund estimates. Actual risks frm expsures t chemical cnstituents at the Sites wuld likely be lwer than the risks estimated herein. Fr estimating carcingenic risk frm expsure t mre than ne carcingenic chemical frm a single expsure rute, risks frm each individual chemical are summed t estimate ttal ECR Ptential Nn-carcingenic Hazards and Excess Cancer Risks Discussin f Nn-carcingenic Hazards Sils/Wasterck Arsenic and lead were identified as COPCs (Table B-9). Arsenic is the nly COPC that can be quantitatively evaluated. The average cncentratin and the 90UCL cncentratin were used as the EPC. Nne f the individual cnstituents exceeded the ODEQ regulatry standard f 1.0 under CTE and RME expsure cnditins. Dc: Final Risk Assessment April 2006 / Page 9

14 Sediments Arsenic and lead were identified as the COPCs. The HQs are belw the ODEQ regulatry standard f 1.0 fr bth the RME and CTE expsure scenaris. Surface water Arsenic and lead were identified as COPCs. The HQs are belw the ODEQ regulatry standard f 1.0 fr bth the RME and CTE expsure scenaris Discussin f Ptential Excess Cancer Risks Sil/Wasterck The nly carcingenic cnstituent identified was arsenic (Appendix B, Table B-10). The average cncentratin and the 90UCL cncentratin were used as the EPCs fr the CTE and RME expsures, respectively. The ECRs exceeded the ODEQ standard f 1 x 10-6 under bth CTE and RME expsure cnditins. Fr the CTE expsure cnditins, ECRs fr ingestin (2 x 10-6 ) did nt exceed the EPA risk range f 1 x 10-4 t 1 x 10-6 but did exceed the ODEQ regulatry standard f 1 x Fr the RME expsure cnditin, ECRs fr ingestin (2 x 10-5 ) and dermal cntact (2 x 10-5 ) did nt exceed the EPA risk range f 1 x 10-4 t 1 x 10-6 but did exceed ODEQ regulatry standard f 1 x Inhalatin f particulates did nt exceed the ODEQ regulatry standard 1 x 10-6 under bth CTE and RME expsure cnditins. A carcingenic risk is pssible frm expsure t arsenic impacted sil/wasterck under the CTE and the RME expsure scenaris. Sediments The nly carcingenic cnstituent identified in sediment is arsenic. The ECRs fr arsenic in sediment did nt exceed the ODEQ regulatry standard 1 x 10-6 under bth CTE and RME expsure cnditins. Surface Water The nly carcingenic cnstituent identified in surface water is arsenic. The ECRs fr arsenic in surface water exceeded the ODEQ regulatry standard f 1 x 10-6 under bth the CTE and the RME expsure cnditins fr bth ingestin and dermal cntact. A carcingenic risk is pssible frm expsure t arsenic impacted surface water under the CTE and the RME expsure scenaris Estimatin f Ptential Human Health Impacts frm Expsure t Lead The USEPA s lead mdels simulate sil lead expsures at a single lcatin. Tw mdels have been develped, the IEUBK mdel and the ALM: These mdels require a minimum f three mnths f cntinuus expsure f at least ne day per week. Three mnths expsure is the minimum t prduce a quasi-steady-state lead cncentratin. The reliability f the mdels fr predicting lead cncentratins fr expsure duratins shrter than three mnths has nt been assessed. In rder t address nn-cntinuus expsures, the USEPA Office f Slid Waste and Emergency Respnse (OSWER) has develped a guidance dcument fr evaluating intermittent expsures t lead fr scenaris such as recreatinal users and trespassers. Dc: Final Risk Assessment April 2006 / Page 10

15 Since the expsure frequency is less than three mnths, predicted intake values were cmpared with the prvisinal values discussed in Sectin Table 3-5 and Table B-11 in Appendix B present the results f the lead intake calculatins and lead screening. Only the ingestin pathway is quantified. EPC (mg/kg) Intake (kg/day) Table 3-5 Lead Intake Screening Predicted Intake (µg/day) USEPA Prvisinal Intake Value (µg/day) USEPA Prvisinal Intake Value (µg/day) CTE RME CTE RME CTE RME Men Children <6 Sil E E Sediment E E TOTAL INTAKE Summary f Sil and Wasterck Lead Risks The predicted intake was calculated t be 0.25 µg/day (CTE) and µg/day (RME). The USEPA prvisinal ingestin intake value fr men (mst likely receptr) is 75 µg/day and children under six (least likely receptr) is 6 µg/day. If yu assume that the ttal intake frm dermal expsure and inhalatin is equal t the intake frm ingestin, n risk is expected fr expsure t lead in sil and wasterck. Summary f Sediment Lead Risks The predicted intake was calculated t be µg/day (CTE) and µg/day (RME). Using the USEPA prvisinal ingestin intake listed abve, n risk is expected fr expsure t lead in sediment fr the mst likely recreatinal receptr (men), but a risk is pssible fr expsure t children under six using the RME EPC. Given the steep terrain and remte nature f the Site, children less than six are nt expected t spend extended perids f time at the Site; therefre, a risk is nt expected frm expsure t lead impacted sediment. Summary f Surface Water Lead Risks The USEPA maximum cntainment level (MCL) fr lead is 15 µg/l. The maximum cncentratin f lead in surface water was mg/l; therefre, expsure t lead in drinking water is nt expected t be a risk. 3.5 CALCULATION OF CLEANUP GOALS Site-specific cleanup gals prtective f the RME recreatinal users were calculated fr sil/wasterck and sediment based n the regulatry standard f 1 x 10-6 ECR. The Site-specific cleanup gals were calculated t be 143 mg/kg ttal arsenic fr sil/wasterck. These clean-up gals are used t calculate ht spt cncentratins in sil/wasterck. 3.6 DETERMINATION OF POTENTIAL HOT SPOTS The 1995 amendments t Oregn Revised Statute [ORS ] and 1997 amendments t the Hazardus Substance Remedial Actin Rules [OAR ], cmmnly referred t as the Envirnmental Cleanup Rules, require that certain actins be taken fr ht spts f cntaminatin. These actins are: Dc: Final Risk Assessment April 2006 / Page 11

16 The identificatin f ht spts as part f the Remedial Investigatin and Feasibility Study, and The treatment f ht spts, t the extent feasible, as part f a remedial actin selected r apprved by the Directr f ODEQ. The intent f the ht spt rule is t require treatment nly fr the wrst cntaminatin, as ppsed t preferring treatment fr all cntaminatin at the Site. A ht spt in sil is generically defined as an area where the cntaminatin is highly cncentrated, highly mbile, r cannt be reliably cntained. The assessment f highly cncentrated ht spts is perfrmed by cmparing the cncentratin f each individual Site cntaminant t its highly cncentrated ht spt level as fllws: The highly cncentrated ht spt levels crrespnd t a lifetime ECR f 1 x 10-4 fr carcingens and a hazard qutient f 10 fr nn-carcingens. The results f the ht spt evaluatins are presented in Tables B-12 and B-13 in Appendix B. Using an ECR f 1 x 10-4, a ht spt cncentratin fr arsenic in sil/wasterck was calculated t be 14,330 mg/kg. N ht spts were identified at the Site. 3.7 SUMMARY OF HUMAN HEALTH RISKS Current and future ptential receptrs were identified as hunters, hikers, and campers. Arsenic and lead were identified as the sil/wasterck, sediment, and surface water nncarcingenic COPCs. N unacceptable nn-carcingenic health effects frm arsenic r lead are anticipated under bth the CTE and RME cnditins. Arsenic was the nly carcingenic COPC identified at the Site. Carcingenic risks were predicted frm expsure t arsenic-impacted surface water and sil/wasterck under bth the CTE and the RME expsure cnditins. N carcingenic risks were predicted frm expsure t sediment. N ht spts were identified at the Site. 4.0 ECOLOGICAL RISK ASSESSMENT The gal f the ERA is t prvide an understanding f the ptential fr eclgical risks due t Site-related cntaminatin and t allw a determinatin f whether remediatin r mre detailed eclgical risk assessment are warranted. This ERA reprt cnsists f: Descriptin f the Site eclgy and likely eclgical receptrs (including rare, threatened r endangered [RTE] species) at r near the Site; Presentatin f the cnceptual eclgical expsure mdel (CEEM), which prvides a summary f ptential and likely expsure media and pathways; Delineatin f assessment endpints and measures; Eclgical risk-based screening; and Risk characterizatin t assess the ptential fr eclgical effects due t Site related COIs. An eclgical survey was cnducted as part f the SI (EA, 2004), which dcumented eclgical features and cnditins at and near the Site. The ptential fr Site-related eclgical impacts were als assessed via an examinatin f stream benthic macrinvertebrate abundance and diversity. The eclgical infrmatin cllected during the SI has been incrprated int this risk assessment as apprpriate. An ODEQ eclgical scping checklist was cmpleted fr this ERA, based n the SI eclgical survey, and is prvided in Appendix C. Dc: Final Risk Assessment April 2006 / Page 12

17 4.1 PROBLEM FORMULATION Prblem frmulatin was cmpleted as fllws: The physical and chemical characteristics f the Site and the imprtant eclgical habitats, plants, invertebrates, fish, and wildlife that exist are described. This infrmatin is utilized t identify the COIs, the eclgical receptrs f cncern, expsure pathways, and the expsure media. This, in turn, allws develpment f the CEEM, which graphically depicts the expected fate and transprt f chemicals at the Site, the ptential expsure media, and likely expsure pathways fr eclgical receptr types f cncern. The prblem frmulatin cncludes with identificatin f the eclgical endpints that delineate the bjectives f the remainder f the ERA. Generally, prblem frmulatin includes a descriptin f the Site and summary f previus investigatins; hwever, this infrmatin is prvided in the SI, and is nt repeated herein Eclgical Stressrs Eclgical receptrs may be affected thrugh expsure t chemicals (i.e., txicity), physical stresses (i.e., destructin f habitat), and bilgical stresses (i.e., viruses and bacteria). Bilgical stressrs were assessed as fllws: While bilgical stressrs may affect eclgical receptrs, they are mre frequently assciated with waste fd r human waste and in areas where wildlife cngregate in large numbers. Because the remte nature f the Site limits human presence and wastes, they are nt cnsidered t pse a threat t eclgical receptrs. Because f the lack f suitable habitat, eclgical receptrs are als unlikely t cngregate in the vicinity f the Site in numbers that culd result in significant bilgical infectin r passage f wildlife diseases. Thus, bilgical stressrs are unlikely t be a significant factr and are nt cnsidered further. Physical stressrs were assessed as fllws: Past physical disturbances include develpment and peratin f the mines and supprting structures, and pssibly histric as well as current lgging peratins. Because the Site has been abandned fr decades, current physical disturbance is reduced t a relatively lw number f recreatinal users that visit r drive by the Site. Given the relatively remte nature f the Site within the Wallwa Whitman Natinal Frest, the eclgical impacts f nging current physical disturbances are limited Eclgical Setting The reginal and Site-specific eclgy are briefly described in this sectin t prvide an understanding f the climate, plants, invertebrates, wildlife, and fish that may inhabit the Site and surrunding regin: Other than RTE species that must be cnsidered n an individual level, a particular species must be ptentially present n r utilize the Site in numbers adequate t allw an expsure level that may result in effects t the species ppulatin. Such significant expsure t Site related COIs will nly ccur fr thse species knwn r expected t use the Site in high numbers n a regular basis r that biaccumulate metals t a significant degree. Mre detailed infrmatin n the reginal and Site eclgy, sensitive envirnments, and RTE species is presented in the SI. Dc: Final Risk Assessment April 2006 / Page 13

18 Bull trut and the mid-clumbia steelhead were the nly threatened r endangered (i.e., prtected) species bserved r expected at r in the vicinity f the Site (EA, 2004). Bull trut were identified in Granite Creek. Steelhead are expected primarily dwnstream f the Site. Fur distinct habitat types were bserved at the Site by EA. These include; drier suth facing slpes, mister nrth facing slpes, riparian znes alng Granite Creek, and spruce frest at Mnumental Mine. A lack f understry grund species was nted during SI activities; and lgging, fire, and insect infestatins have likely ccurred in areas surrunding the Site. Wasterck piles typically included early-successinal cniferus species. Overall, the relatively large number f species identified during this limited eclgical survey suggested that numerus species are present in the vicinity f the Site and that they utilize varied habitat and fraging methds. Granite Creek flws thrughut the Site and is generally less than ne meter wide, with a riparian area less than 20 meters wide. EA described the riparian vegetatin as being dminated by red alder (EA, 2004), althugh it is mre likely muntain alder that was bserved Cnceptual Eclgical Expsure Mdel The CEEM (Figure 4-1) graphically depicts the surces f cntaminatin, cntaminant release and transprt mechanisms, impacted expsure media, and expsure rutes fr eclgical receptr types bserved r expected at the Site. Based n current understanding f Site cnditins, the ptentially cntaminated expsure media fr eclgical receptrs include: Surface sil/wasterck in the vicinity f the Site; Vegetatin at the Site; Surface water in Granite Creek, adit and wasterck seep drainages; Pre water within Granite Creek; and Sediment in Granite Creek. Given these expsure media, the pssible and likely eclgical receptr grups include: Terrestrial plants expsed t COIs in sil/wasterck; Terrestrial invertebrates expsed t COIs in sil/wasterck; Terrestrial and semi-aquatic wildlife (including birds, mammals, and reptiles) expsed t COIs in sil/wasterck, surface/adit water, pre water, and sediment; Aquatic life (including aquatic plants, aquatic invertebrates, fish, and amphibians) expsed t COIs in surface/adit water, and pre water; and Benthic invertebrates, birds, and mammals expsed t COIs in sediment Assessment Endpints and Measures Assessment Endpints Assessment endpints represent the eclgical aspects t be prtected at a site and link the ERA t risk management decisins. Within a screening level ERA, assessment endpints are generalized t reflect the risk-based screening prcess and prtective eclgical risk-based screening cncentratins (ERBSCs). The assessment endpints fr this ERA include: Prtectin f the reprductin and survival f plants, terrestrial invertebrates, birds, mammals, and reptiles expsed t COIs in surface sil/wasterck and vegetatin at the Site; Dc: Final Risk Assessment April 2006 / Page 14

19 Prtectin f the reprductin and survival f aquatic life expsed t COIs in water within the adit/seep drainages and Granite Creek; Prtectin f the reprductin and survival f birds and mammals that may drink water frm adit/seep drainages and Granite creek; Prtectin f the reprductin and survival f aquatic life expsed t COIs in pre water within Granite Creek; Prtectin f the reprductin and survival f benthic macrinvertebrates expsed t COIs in sediment within Granite Creek; and Prtectin f the reprductin and survival f birds and mammals expsed via the aquatic/benthic fd chain t COIs in sediment within Granite Creek Assessment Measures Assessment measures are characteristics f the Site, selected eclgical receptrs, r ecsystem aspects that are measured thrugh mnitring r sampling activities. Assessment measurements are then related, qualitatively r quantitatively, t the selected assessment endpint(s) in rder t determine whether an eclgical effect is ccurring. Fr this ERA, the assessment measures are cmprised f the fllwing: Measured cncentratins in sil/wasterck, surface water, pre water, and sediment; and Readily-available ERBSCs. 4.2 ECOLOGICAL RISK-BASED SCREENING Eclgical risk-based screening begins with a list f COIs in the media f cncern, a determinatin f EPCs, and a cmparisn f the EPCs t ERBSCs with cnsideratin f expsure t multiple chemicals and media, reprting limit adequacy, and the inrdinate cntributin f individual chemicals t the verall receptr grup risk. The result is a list f Site-related chemicals f ptential eclgical cncern (COPECs) with the ptential t pse risks t eclgical receptrs at the Site. The initial screening was cmpleted in Sectin 2.0 and the chemicals retained as eclgical COIs were presented in Table 2-1. The ERBSCs used in the risk-based screening were screening level values (SLVs) prvided by ODEQ (ODEQ, 2001). When an SLV was nt available fr a given COI, an alternative ERBSC was selected frm peer-reviewed literature r a surrgate chemical ERBSC was substituted. The ERBSCs are presented in Table D-1. As per ODEQ guidance (2001), the EPCs fr each medium were cmpared t the ERBSCs fr each chemical and receptr grup in each medium, resulting in chemical/receptr grup-specific risk ratis (R ij in Tables D-2 thrugh D-5). Assessment f risk ratis was as fllws: Risk ratis were summed fr all chemicals within a receptr grup t btain receptr grupspecific risk ratis (R j in Tables D-2 thrugh D-5). The ptential fr biaccumulatin f each COI was assessed, reprting limit adequacy was checked fr undetected COIs, and the inrdinate cntributin f any given chemical t the verall receptr grup risk was determined. Risk ratis greater than 1 were cnsidered unacceptable and indicative f ptential risks fr prtected eclgical receptrs (bull trut and steelhead), aquatic life, and benthic macrinvertebrates. Risk ratis greater than 5 were cnsidered unacceptable fr ther eclgical receptrs. The COIs fr which ptential eclgical risks were indicated became COPECs fr the Site. Dc: Final Risk Assessment April 2006 / Page 15

20 N ERBSCs are available fr vegetatin; therefre, a risk-based screening was nt cnducted fr plant species. The ptential fr COPECs in vegetatin t result in eclgical risks is discussed further in the risk characterizatin sectin belw. The risk ratis fr receptr grups expsed t COPECs are shwn in Tables 4-1 thrugh 4-4. Table 4-1 Chemicals f Ptential Eclgical Cncern and Risk Ratis Fr Surface Sil/Wasterck COPEC Terrestrial Terrestrial Birds Mammals Plants N* Invertebrates n* N* (R (R ij ) (R ij ) ij ) (R ij ) n* Antimny N ERBSC Ttal Arsenic Cadmium Irn 2, N ERBSC 0 N ERBSC 0 Lead Manganese Mercury , Selenium Silver N ERBSC 0 N ERBSC 0 Vanadium 22 5 N ERBSC Zinc Ttal Receptr Grup Risk (R j ) 3,020 1, Bld = COPEC with risk rati greater than acceptable levels; (>1 fr prtected species - nne are expected; >5 fr unprtected species) Nn-bld = selected as COPECs fr reasns ther than exceedance f an ERBSC. * n = number f statins with an unacceptable risk rati. Table 4-2 Chemicals f Ptential Eclgical Cncern and Risk Ratis Fr Surface Water Chemical f Ptential Eclgical Cncern Aquatic Life (R ij ) N* Birds (R ij ) n* Mammals (R ij ) Arsenic, Ttal Barium Irn N ERBSC N ERBSC Lead Mercury Selenium Ttal Receptr Grup Risk (R j ) Bld = COPEC with risk rati greater than acceptable levels (>1 fr aquatic life; >5 fr ther species). Nn-bld = selected as COPECs fr reasns ther than exceedance f an ERBSC. * n = number f statins with an unacceptable risk rati. n* Dc: Final Risk Assessment April 2006 / Page 16

21 Table 4-3 Chemicals f Ptential Eclgical Cncern and Risk Ratis fr Pre Water Chemical f Ptential Eclgical Cncern Aquatic Life (R ij ) Arsenic, Ttal Barium Irn Lead Mercury Selenium Silver Reprting Limit T High 11 Thallium Ttal Receptr Grup Risk (R j ) 14 Bld = COPEC with risk rati greater than acceptable levels (>1 fr aquatic life; >5 fr ther species). Nn-bld = selected as COPECs fr reasns ther than exceedance f an ERBSC. * n = number f statins with an unacceptable risk rati. n* Table 4-4 Chemicals f Ptential Eclgical Cncern in Sediment Benthic Macrinvertebrates n* (R ij ) (R ij ) Chemical f Ptential Eclgical Cncern Birds and Mammals Aluminum N ERBSC N ERBSC Arsenic, Ttal Barium N ERBSC N ERBSC Beryllium N ERBSC Cadmium Cbalt N ERBSC N ERBSC Irn N ERBSC N ERBSC Mercury N ERBSC Selenium N ERBSC Thallium N ERBSC 1 Vanadium N ERBSC N ERBSC Zinc Ttal Receptr Grup Risk (R j ) Bld = COPEC with risk rati greater than acceptable levels (>1 fr benthic invertebrates; >5 fr ther species). Nn-bld = selected as COPECs fr reasns ther than exceedance f an ERBSC. * n = number f statins with an unacceptable risk rati. N* Dc: Final Risk Assessment April 2006 / Page 17

22 4.3 ECOLOGICAL RISK CHARACTERIZATION Risk Descriptin Risk descriptin invlves examining the predicted risks in each medium t determine whether they are likely, r artifacts f the risk assessment prcess Surface Sil/Wasterck The COPECs fr sil/wasterck were listed in Table 4-1. COPECs are summarized belw: Cadmium and selenium were selected as COPECs due t the ptential t biaccumulate. The synthetic precipitatin leaching prcedure (SPLP) results fr these tw COPECs (EA, 2004) suggest that they are strngly bund t sil/wasterck particles, and thus, are nt readily biavailable. As such, it is unlikely they will biaccumulate t any significant degree in birds r mammals. Based n this and the lack f an exceedance f ERBSCs by the EPC, cadmium and selenium are nt cnsidered t present a significant risk t eclgical receptrs. Arsenic, irn, and mercury risk ratis were inrdinately high fr at least ne receptr grup. Irn and mercury nly exceeded ERBSCs at tw and three sample lcatins, respectively; all but ne f these exceedances were in three samples cllected at the Mnumental Mine. Irn cncentratins exceeded the assciated backgrund cncentratins by a maximum factr f nly 1.3. Fr mercury, the highest exceedences f ERBSCs ccurred in plants and invertebrates. The nly ther exceedences bserved with regard t mercury ccurred at the Mnumental Mine in three sample lcatins fr birds and ne sample lcatin fr mammals. Overall, predicted risks fr ttal arsenic are spread acrss receptr grups and sampling lcatins, whereas predicted risks fr mercury and irn are limited primarily t plants and invertebrates at the Mnumental Mine. The five COPECs with unacceptable risk ratis at mre than three sample lcatins included ttal arsenic, lead, silver, vanadium and zinc. Silver had five unacceptable risk ratis (fur plant and ne invertebrate) at the Mnumental Mine. Zinc had 13 unacceptable risk ratis (7 fr plants, 1 fr invertebrates, and five fr birds), primarily at the Mnumental and Tillicum Mines. Lead had 11 unacceptable risk ratis (5 fr plants and 6 fr birds) in samples cllected at 4 f the mines. Vanadium had five unacceptable risk ratis fr plants spread acrss all the mines. Ttal arsenic had multiple unacceptable risk ratis fr multiple receptrs at all the mines; the majrity f these ratis were bserved at the Mnumental and Tillicum Mines. Based n the number and lcatins f samples where the unacceptable exceedances f ERBSCs and backgrund cncentratins ccurred, the results f the risk-based screening suggest that: Ttal arsenic pses ptential risks t multiple receptr grups at the Mnumental and Tillicum Mines. Mercury, silver, and zinc may pse risks, primarily at the Mnumental Mine. Zinc may als pse unacceptable risks t plants at the Tillicum Mine. Dc: Final Risk Assessment April 2006 / Page 18

23 Vegetatin Vegetatin samples were cllected frm fur backgrund and six lcatins likely t be impacted by Site-related COPECs. The COPECs present in vegetatin abve backgrund cncentratins included ttal arsenic, beryllium, cadmium, ttal chrmium, cpper, irn, lead, mercury, vanadium, and zinc (See Table A-4 in Appendix A). The maximum ratis f nsite cncentratins t backgrund cncentratins were ttal arsenic, (10), beryllium (1), cadmium (7), ttal chrmium (5), cpper (1), irn (2), lead (2), mercury (2), vanadium (1), and zinc (3). Beryllium, cpper, irn, lead, mercury, and vanadium are present at less than r apprximately equivalent t tw times the backgrund cncentratin and, thus, are nt cnsidered t present a significant ptential fr eclgical impacts. Zinc is an essential nutrient in the envirnment that is nly mderately elevated in vegetatin cmpared t its backgrund cncentratins. This diminishes the predicted ptential fr impacts due t zinc. Ttal arsenic and cadmium significantly exceeded backgrund cncentratins at the Mnumental Mine, while ttal chrmium significantly exceeded backgrund cncentratins at the Central Mine. Overall, ttal arsenic, cadmium, and ttal chrmium are the COPECs f greatest cncern in vegetatin. Limited amunts f vegetatin are lcated n r near the wasterck piles at the Site; therefre, the ptential expsure f herbivres t Site-related cntaminatin is significantly reduced Surface Water The COPECs fr surface water are listed in Table 4-2. N backgrund surface water samples were cllected during the SI. Barium was the nly cnstituent t exceed applicable ERBSCs. The differences between the highest and lwest detected cncentratins was less than a factr f three, and less than r equivalent t a factr f tw, with the exceptin f sample SP-SFW- 19 at the Mnumental Mine. Therefre, barium is nt cnsidered t be significantly elevated. Irn was selected as a COPEC based n the lack f ERBSCs. Irn was nly detected in tw samples at very lw cncentratins, and the difference between the highest and lwest detected cncentratin was less than a factr f three. Irn is therefre nt cnsidered t be significantly elevated at the Site. Ttal arsenic, lead, mercury, and selenium cncentratins did nt exceed ERBSCs, but were selected as COPECs based n biaccumulatin ptential. Ttal arsenic was detected in fur samples; lead was detected in three samples; mercury in tw samples; and selenium in ne sample. These detectins ccurred primarily in the farthest upstream and/r the farthest dwnstream samples. The limited number f detectins suggests that these COPECs are nt widespread and thus, are nt likely t biaccumulate significantly. Hwever, the presence f these metals at the Mnumental Mine and the reappearance dwnstream frm the Central Mine, suggests a ptential fr these mines t be surces f COPECs t Granite Creek. Overall, slightly elevated cncentratins f a few COPECs were nted at the upstream and dwnstream surface water statins. Dc: Final Risk Assessment April 2006 / Page 19

24 Pre Water The COPECs fr pre water were listed abve in Table 4-3. N backgrund pre water samples were cllected during the SI. Barium was the nly detected COPEC that exceeded an ERBSC. The difference between the lwest and highest detected cncentratins was less than a factr f 2; therefre, barium is nt cnsidered t be significantly elevated at the Site. Thallium was selected as a COPEC due t a lack f ERBSCs. Thallium was detected in ne sample at very lw cncentratins and the difference between the highest detectin and lwest detectin limit was less than a factr f 3. Thallium is nt cnsidered t be significantly elevated at the Site. Ttal arsenic, lead, mercury, and selenium cncentratins did nt exceed ERBSCs, but were selected as COPECs based n biaccumulatin ptential. As with surface water, the presence f these metals in nly a few sample lcatins at very lw cncentratins strngly suggests the presence is nt likely t result in ppulatin level eclgical impacts. Hwever, it shuld be nted the highest detected ttal arsenic cncentratins ccurred in samples cllected frm the tw farthest dwnstream statins n Granite Creek. Silver was nt detected in pre water at the Site, but ne-half the detectin limit exceeds the ERBSC by a maximum factr f 12. Because silver was nt detected in any surface water r pre water samples and the detectin limits are relatively lw (2.9 micrgrams per liter [µ/l]), it is cnsidered unlikely silver cntributes t eclgical risks at the Site Sediment The COPECs fr sediment were listed abve in Table 4-4. N backgrund sediment samples were cllected during the SI. Ttal arsenic, cadmium, selenium, and zinc were the nly COPECs with unacceptable risk ratis. The predicted risks fr ttal arsenic, cadmium, and zinc were spread widely acrss the Site. The highest risk ratis ccurred in samples cllected frm the fur statins lcated farthest dwnstream. Selenium risk ratis were all less than 10 in 8 f the 20 sample lcatins and were spread intermittently acrss the Site. Aluminum, barium, beryllium, cbalt, irn, thallium, and vanadium were selected based n a lack f ERBSCs. Since n backgrund samples were cllected, the difference between the highest and lwest detectin limit was examined fr these COPECs. The difference fr aluminum, barium, beryllium, cbalt, and irn were less than a factr f 10; thallium and vanadium had differences that were factrs f 14 and 12, respectively. Three statins (PSD-03, RSD-06, RSD-10) cntained the highest cncentratins f irn, thallium, and vanadium, whereas samples cllected frm the remainder f the statins cntained cmparable COPEC cncentratins. Mercury was selected as a COPEC due t the lack f a bird/mammal ERBSC and the ptential fr biaccumulatin; the maximum mercury detectin is apprximately 12 times higher than the lwest detectin at statin PSD-54. Overall, ttal arsenic, cadmium, and zinc were detected at multiple lcatins alng the entire length f Granite Creek at the Site and have the ptential t cause eclgical impacts. Ptential impacts due t mercury and selenium are less likely, but the distributin f these COPECs may suggest they are Site-related. Dc: Final Risk Assessment April 2006 / Page 20

25 4.3.2 Eclgical Ht spts Eclgical ht spts are defined as cncentratins that are 10 times greater than the ERBSCs. Antimny, ttal arsenic, cpper, lead, mercury, silver, and zinc ht spts were identified in multiple wasterck samples. Barium ht spts were identified in several surface water and pre water samples. Ttal arsenic, cadmium, and zinc ht spts were identified in several sediment samples. N backgrund samples were cllected fr surface water, pre water, r sediment; therefre: The eclgical ht spt analysis fr these media is based slely upn exceedance f the ERBSC by a factr f 10 r mre. Table 4-5 Lcatins f Eclgical Ht Spts Sil Surface Water Pre Water Sediment MM-ML-SSS-16 MM-ML-SSS-38 MM-SP-SFW-18 TM-ST-PWP-07 CMM-ST-PSD-03 MM-WP-SSS-13 MM-SP-SFW-19 TM-ST-PWP-08 CMM-ST-RSD-03 MM-WP-SSS-14 MM-SP-SFW-51 CM-ST-PWP-09 CMM-ST-RSD-04 MM-WP-SSS-15 CMM-ST-SFW-04 CM-ST-PWP-10 SM-ST-PSD-05 MM-WP-SSS-17 SM-ST-SFW-06 CM-ST-PWR-10 SM-ST-PSD-06 CMM-WP-SUS-21 TM-ST-SFW-07 GC-ST-PWP-53 SM-ST-RSD-05 TM-WP-SSS-28 TM-ST-SFW-08 GC-ST-PWP-54 SM-ST-RSD-06 TM-WP-SUS-26 CM-ST-SFW-09 TM-ST-PSD-07 TM-WP-SSS-27 CM-ST-SFW-10 TM-ST-PSD-08 CM-WP-SSS-31 GC-ST-SFW-53 TM-ST-RSD-07 GC-ST-SFW-54 TM-ST-RSD-08 CM-ST-PSD Uncertainty Analysis The uncertainty analysis lists the cmmn uncertainties assciated with eclgical risk-based screening and assesses whether they are likely t ver- r underestimate the ptential fr eclgical risks t be realized at the Site. The primary uncertainties assciated with this eclgical risk-based screening and the impacts n the predictin f the ptential fr eclgical risks are discussed belw: The risk-based screening assumes the receptrs are cnstantly expsed t the chemical at a cncentratin equal t the EPC. This may be true fr immbile species such as plants and sme terrestrial invertebrates; hwever, unless the cntaminatin is widely and evenly spread, it is nt realistic fr wildlife species. Because the metals are primarily lcated arund wasterck piles and small centers f mining activity, the risks calculated abve verestimate the actual risks psed t wildlife. The use f maximum detected cncentratin r 90UCL as the EPC is a cnservative apprach that is purpsefully designed t result in sme verestimatin f the ptential fr eclgical risks. Because f this, the risks predicted are likely t verestimate actual eclgical risks. Including a sample s labratry reprting limit screening is a cnservative apprach that includes COIs as COPECs when nt actually detected. Because the undetected COI is likely present at cncentratins less than the reprting limit, pssibly much less, including the COI as a COPEC results in an verestimatin f the ptential fr eclgical risks. Dc: Final Risk Assessment April 2006 / Page 21

26 The lack f site-specific biavailability data des nt allw fr a frmal assessment f risks due t sme COPECs fr upper trphic level receptrs (i.e., birds and mammals). Hwever, the fact that many metals bind strngly t sil and sediment particles suggests that many f the metals may nt be readily biavailable. Given this, risks due t the biaccumulatin f COPECs are likely verestimated. Except fr benthic macrinvertebrates and aquatic life, the ERBSCs used fr this ERA are intended t be n-bserved-adverse-effect-levels (NOAELs). Because actual eclgical effects ccur at an unknwn cncentratin smewhere between the NOAEL and the LOAEL, simply exceeding an ERBSC des nt necessarily indicate the ptential fr significant eclgical effects. Thus, the use f NOAEL-based ERBSCs likely results in an verestimatin f the ptential fr eclgical risk. The lack f ERBSCs fr sme receptrs precludes the calculatin f risk fr thse receptrs, which may result in an ver- r underestimatin f the ptential fr eclgical risks. The use f a biaccumulatin screening is a cnservative measure used t assess the ptential fr risks psed t upper trphic level eclgical receptrs when apprpriate ERBSCS are missing. Within this ERA, predictins are made regarding the significance f eclgical expsures under current cnditins at the Site. Overall, the risk-based screening is designed t verestimate the ptential fr eclgical risks. 4.4 SUMMARY OF ECOLOGICAL RISKS Predicted eclgical risks due t ttal arsenic are widespread in wasterck at all five mines, with the Mnumental and Tillicum Mines exhibiting the highest predicted risk. T a lesser extent, antimny, irn, lead, mercury, silver, vanadium, and zinc als cntribute t the predicted risks. Immbile receptrs, such as plants and invertebrates, are likely impacted by wasterck. Individual birds and small mammals are als likely t be impacted by wasterck; hwever, ppulatin level impacts are nt expected t the mre mbile terrestrial species. The majrity f eclgical ht spts were assciated with ttal arsenic in wasterck at the Mnumental and Tillicum Mines; eclgical ht spts were als identified fr antimny, ttal arsenic, lead, mercury, and silver, and were spread acrss the Mnumental, Tillicum, and Central Mines. Cadmium and ttal chrmium in vegetatin at the Site were detected at cncentratins greater than five times the backgrund vegetatin cncentratin; ttal arsenic was elevated mre than 10 times higher than backgrund indicating that vegetatin at the Site may be impacted. Barium was the nly COPEC in surface water and pre water that exhibited eclgical risk. These risks and sme f the ther COPECs likely wuld nt have been identified if backgrund samples wuld have been cllected frm Granite Creek. Nt including barium, all ther COPECs were selected based n biaccumulatin ptential r a lack f ERBSCs. While barium and silver ht spts were nted in surface water and pre water, it is likely related t the lack f backgrund cncentratin data fr barium and the elevated detectin limits fr silver. The highest cncentratins f several COPECs in surface water and pre water were bserved in samples cllected at the farthest upstream and dwnstream sample lcatins, which suggests the Mnumental Mine and Central Mine may be a surce f COPECs t Granite Creek. Dc: Final Risk Assessment April 2006 / Page 22

27 Elevated risk ratis fr ttal arsenic, cadmium, selenium, and zinc were identified in sediment. Ttal arsenic, cadmium, and zinc appear likely t have the highest ptential t impact immbile receptrs r thse that are frequently expsed t COPECs in sediment. Ht spts fr several metals were nted at nearly all the sediment sampling lcatins. The lack f backgrund samples may have resulted in the inclusin sme f the COPECs with elevated risk ratis and ht spts, when in fact they may be present belw backgrund cncentratins. 5.0 CONCLUSIONS The fllwing cnclusins were develped frm the HHRA: Current and future ptential receptrs were identified as hunters, hikers, and campers. Arsenic and lead were identified as the sil/wasterck, sediment, and surface water nncarcingenic COPCs. N unacceptable nn-carcingenic health effects are anticipated under bth the CTE and RME cnditins. Arsenic was the nly carcingenic COPC identified at the Site. Carcingenic risks were predicted frm expsure t arsenic-impacted surface water and sil/wasterck under bth the CTE and the RME expsure cnditins. N carcingenic risks were predicted frm expsure t sediment. N ht spts were identified at the Site. The fllwing cnclusins were develped frm the ERA: Eclgical impacts were predicted fr immbile species, primarily terrestrial plants and terrestrial invertebrates, due t COPECs in sil and wasterck. Lcal and reginal ppulatins f these and ther terrestrial species are unlikely t be significantly impacted. Eclgical impacts were als predicted fr aquatic life and wildlife expsed t COPECs in surface water and pre water. Hwever, the lack f backgrund COPEC cncentratins fr these media made it mre difficult t predict the ptential fr impacts. Benthic invertebrates and wildlife appear t have the ptential t be impacted by ttal arsenic, cadmium, and zinc, which are present at elevated cncentratins, at nearly all sediment sample lcatins. The lack f backgrund COPEC cncentratins in sediment likely results in an verestimatin f these ptential impacts. The Mnumental and Tillicum Mines appear t have mre lcatins with elevated COPEC cncentratins in wasterck than the ther mines. 6.0 RECOMMENDATIONS Based n the infrmatin presented in this reprt, CES recmmends the fllwing: Perfrming an Engineering Evaluatin / Cst Analysis (EECA) at the Site because: Unacceptable carcingenic risks were predicted frm expsure t arsenic in wasterck under the CTE and RME recreatinal expsure scenaris. Eclgical risks were predicted frm expsure t multiple COPECs in all media. Multiple eclgical ht spts were identified in all media. As part f the EECA, a data gap investigatin shuld be cmpleted, a preliminary list f data gaps are listed belw: Cllect additinal backgrund sil samples in rder t accurately calculate the 90UCL fr backgrund cncentratins. Cllect backgrund surface water and sediment samples frm Granite Creek. Cllect additinal sil samples alng the banks f Granite Creek t assess the impacts frm the Site. Dc: Final Risk Assessment April 2006 / Page 23

28 Perfrm additinal recnnaissance f each mine t verify Site cnditins, lcate additinal wrkings, and cllect additinal sil, wasterck and tailings samples in rder t delineate the extent f cntaminatin. Perfrm a detailed tpgraphic survey at each mine; this infrmatin will be used t accurately determine the vlume f wasterck and material at the Site. Rerun the risk assessment calculatins, including the additinal samples cllected, t further evaluate the human and eclgical risks at the Site. USFS Disclaimer: This abandned mine/mill site was created under the General Mining Law f 1872 and is lcated slely n Natinal Frest System (NFS) lands administered by the USDA Frest Service. The United States has taken the psitin and curts have held that the United States is nt liable as an wner under CERCLA Sectin 107 fr mine cntaminatin left behind n NFS lands by miners perating under the 1872 Mining Law. Therefre, USDA Frest Service believes that this site shuld nt be cnsidered a federal facility within the meaning f CERCLA Sectin 120 and shuld nt be listed n the Federal Agency Hazardus Waste Cmpliance Dcket. Instead, this site shuld be included n EPA s CERCLIS database. Cnsistent with the June 24, 2003 OECA/FFEO Plicy n Listing Mixed Ownership Mine r Mill Sites Created as a Result f the General Mining Law f 1872 n the Federal Agency Hazardus Waste Cmpliance Dcket, we respectfully request that the EPA Reginal Dcket Crdinatr cnsult with the Frest Service and EPA Headquarters befre making a determinatin t include this site n the Federal Agency Hazardus Waste Cmpliance Dcket. Prepared by: CASCADE EARTH SCIENCES Dustin G. Wasley, PE Managing Engineer II Exp. 06/30/2006 Dc: Final Risk Assessment April 2006 / Page 24