Risk Assessment Work Plan Salt Chuck Mine Remedial Investigation Ton gass Nationa Prepared for U.S. Environmental Protection Agency Region 10 I - ... - % - ^ m f LU June 2013 Prepared by ^ CH2MHILL. AES10 Architect and Engineering Services Contract Contract No. 68-S7-04-01 ------- ------- Contents Acronyms and Abbreviations v 1. Introduction 1-1 1.1 Purpose of the Risk Assessment 1-1 1.2 Orga nization of this Work Plan 1-1 2. Conceptual Site Model 2-1 2.1 Site Description 2-1 2.1.1 History 2-2 2.1.2 Climate 2-2 2.2 Site Hydrology 2-2 2.2.1 Adit Discharge 2-2 2.2.2 Unnamed Stream 2-2 2.2.3 Lake Ellen Creek 2-3 2.2.4 Salt Chuck Bay 2-3 2.3 Ecological Setting 2-3 2.3.1 Wetlands 2-3 2.3.2 Aquatic Life 2-3 2.3.3 Wildlife 2-5 2.3.4 Threatened and Endangered Species 2-5 2.4 Current and Reasonably Anticipated Land Uses 2-5 2.5 Water Uses 2-7 2.5.1 Surface Water 2-7 2.5.2 Groundwater 2-7 2.6 Conceptual Exposure Model 2-7 2.6.1 Sources 2-7 2.6.2 Release Mechanisms and Potential Transport Media 2-12 2.6.3 Potentially Complete Human Exposure Pathways and Receptors 2-12 2.6.4 Potentially Complete Ecological Exposure Pathways and Receptors 2-13 3. Data Usability and Processing 3-1 3.1 Data Usability 3-1 3.2 Data Processing Procedures 3-1 4. Human Health Risk Assessment Methodology 4-1 4.1 Human Health Risk Assessment Guidance 4-1 4.2 Identification of Chemicals of Potential Concern for Human Health 4-1 4.2.1 COPC Selection Process 4-2 4.3 Human Exposure Assessment 4-2 4.3.1 Estimating Exposure Point Concentrations 4-3 4.3.2 Human Exposure Assumptions 4-3 4.3.3 Calculation of Chemical Intake 4-4 4.4 Human Health Toxicity Assessment 4-8 4.4.1 Reference Doses for Noncancer Effects 4-9 4.4.2 Slope Factors for Cancer Effects 4-9 4.4.3 Sources of Toxicity Values 4-10 4.4.4 Use of Toxicity Equivalency Factors for PAHs 4-11 4.5 Human Health Risk Characterization 4-11 4.5.1 Noncancer Hazard Estimation 4-11 4.5.2 Cancer Risk Estimation 4-12 ES011013043021SEA III ------- CONTENTS 4.5.3 Risk Estimation Method for Lead 4-13 4.5.4 Consideration of Contribution from Ambient Levels of Metals 4-13 4.5.5 Action Levels for Human Health 4-14 4.6 Uncertainty Analysis 4-14 5. Ecological Risk Assessment Methodology 5-1 5.1 Ecological Risk Assessment Guidance 5-1 5.2 EPA's Risk Assessment Process 5-1 5.3 Screening Level Problem Formulation (Step 1) 5-3 5.3.1 Selection of Representative Endpoint Species 5-3 5.3.2 Assessment and Measurement Endpoints 5-4 5.4 Screening Level Exposure Estimate and Risk Calculation (Step 2) 5-4 5.4.1 Soil Screening Values 5-4 5.4.2 Surface Water Screening Values 5-5 5.4.3 Sediment Screening Values 5-5 5.4.4 Screening Risk Calculation 5-5 5.4.5 Recommendation for SMDP 1 5-5 5.5 Baseline Ecological Risk Assessment Problem Formulation (Step 3) 5-5 5.5.1 Refinements to Risk Estimates 5-6 5.5.2 Wildlife Exposure Modeling 5-7 5.5.3 Wildlife Ecological Effects Assessment 5-9 5.5.4 Risk Characterization Methodology 5-10 5.5.5 Uncertainties 5-10 5.5.6 Recommendation for SMDP 2 5-11 6. Risk Assessment Report 6-1 7. References 7-1 Tables (Tables are provided at the end of the main text) 1 2009-2011 Climate Summary for Craig, Alaska 2 Marine IntertidaI Invertebrates Potentially Occurring at Prince of Wales Island 3 Fish and Amphibian Species Potentially Occurring at Prince of Wales Island 4 Bird Species Potentially Occurring at Prince of Wales Island 5 Terrestrial and Marine Mammals Potentially Occurring at Prince of Wales Island 6 Exposure Assumptions forthe Human Health Risk Assessment 7 Toxicity Factors forthe Human Health Risk Assessment 8 Assessment and Measurement Endpoints forthe Ecological Risk Assessment 9 Wildlife Exposure Assumptions Figures 1 Location and Site Features 2 National Wetlands Inventory Map 3 Land Use Status in the Vicinity of Salt Chuck Mine 4 Conceptual Site Model for Potential Human Exposures forthe I ntertida I Areas 5 Conceptual Site Model for Potential Human Exposures forthe Upland Areas 6 Conceptual Site Model for Potential Ecological Exposures forthe I ntertida I Areas 7 Conceptual Site Model for Potential Ecological Exposures forthe Upland Areas 8 EPA's Eight-step Ecological Risk Assessment Process for Superfund IV ES011013043021SEA ------- Acronyms and Abbreviations °F degrees Fahrenheit Hg/dL micrograms per deciliter Hg/m3 micrograms per cubic meter Hg/mg microgram per milligram ABS absorption fractions ABSgi Gastrointestinal absorption efficiency ADAF Age Dependent Adjustment Factors ADNR Alaska Department of Natural Resources AET apparent effects threshold AF Skin adherence factor ALM Adult Lead Model AT Averaging time ATSDR Agency for Toxic Substances and Disease Registry AUF area use factor BAF bioaccumulation factor BAFL Diet-to-animal tissue lipid bioaccumulation factor BCF bioconcentration factor BERA baseline ecological risk assessment bgs below ground surface Bij Constituent concentration (j) in biota type (i) BW body weight BWa adult body weight BWC child body weight CAE PA California Environmental Protection Agency CF conversion factor cfs cubic feet per second cm/hour centimeters per hour cm2 square centimeter CO PC Chemical of potential concern COPEC chemical of potential ecological concern cP Constituent concentration in wild plants cPAH carcinogenic polynuclear aromatic hydrocarbon Cs Constituent concentration in soil or sediment CSM conceptual site model Csw Constituent concentration in surface water Ct Constituent concentration in shellfish tissue Cw Constituent concentration in surface water DAevent Absorbed dose per event DQO data quality objective EC exposure concentration ECa Exposure concentration in air Eco-SSL U.S. EPA Ecological Soil Screening Level ED Exposure duration EDa Adult exposure duration EDC Child exposure duration EE/CA Engineering Evaluation/Cost Analysis EF Exposure frequency Ej Estimated COPEC exposure or Total exposure ES011013043021SEA V ------- ACRONYMS AND ABBREVIATIONS ELCR EPA EPC EPI ERA ER-M ESV ET F FCV FIR Forest Service FRX g/day HHRA HQ HQinh hr/event IEUBK IFPadj Intake IRIS IRPa IRPC IRs IRt IRw IUR kg kgdiet/kgbw-day KP L/ kgbw-day L/day LOAEL LT m3/kg MDL MF mg/ cm2 mg/cm2-event mg/cm3 mg/day mg/kg mg/kgbw/day mg/kg-day mg/L mg/m3 mg-year/kg-day MRL N NAWQC excess lifetime cancer risk U.S. Environmental Protection Agency exposure point concentration Estimation Program Interface ecological risk assessment effects range-median ecological screening value Exposure time Fraction of game animal diet originating from site freshwater chronic value Total food ingestion rate forthe representative species United States Department of Agriculture, Forest Service Foraging range for target species x grams per day human health risk assessment hazard quotient Noncancer hazard quotient from inhalation hour per event Integrated Exposure Uptake Biokinetic Age-adjusted plant ingestion factor Chronic daily intake averaged over a lifetime Integrated Risk Information System Adult wild plant ingestion rate Child wild plant ingestion rate Soil or sediment ingestion rate Shellfish tissue ingestion rate or wild game ingestion rate Surface water ingestion rate Inhalation unit risk kilogram kilograms diet per kilograms body weight per day Dermal permeability coefficient liters per kilograms body weight per day liters per day lowest observed adverse effect level Fraction of game animal tissue as lipid cubic meters per kilogram method detection limits migration factor milligrams per square centimeter milligrams per square centimeter per event milligrams per cubic centimeter milligrams per day milligrams per kilogram milligrams per kilograms body weight per day milligrams per kilograms per day milligrams per liter milligrams per cubic meter milligrams per year per kilograms per day Minimal Risk Level Number of chemicals U.S. EPA National Ambient Water Quality Criteria ES011013043021SEA ------- A3R0NYM S AND ABBREVIATIONS NHPA National Historic Preservation Act NOAA National Oceanic and Atmospheric Association NOAEL no observed adverse effect level ORNL Oak Ridge National Laboratory PAH polynuclear aromatic hydrocarbon PEC probable effect concentration PEF particulate emission factor PGE platinum group element Pi Proportion of biota type (i) in diet Pp Proportion of animal diet as wild plants PPRTV U.S. EPA Provisional Peer Reviewed Toxicity Value Ps Proportion of diet as incidentally ingested soil RAGS Risk Assessment Guidance for Superfund RAWP Risk Assessment Work Plan RfC reference concentration RfD reference dose value RfDABs Absorbed reference dose RfD, Reference dose ofthe ith chemical RfD0 Oral reference dose RI/FS Remedial Investigation/ Feasibility Study Risk Excess lifetime cancer risk Risk, Cancer risk for the ith chemical Riskmh Excess lifetime cancer risk from inhalation RiskT Total cancer risk from route of exposure RME reasonable maximum exposure SA Exposed skin surface area SF slope factor SFabs Absorbed slope factor SF0 Oral slope factor Sj Constituent concentration in soil/sediment SLERA screening level ecological risk assessment SMDP Scientific Management Decision Point SQuiRT NOAA Screening Quick Reference Table SSL Soil Screening Level T&E Threatened and endangered TEC threshold effect concentration TEF toxicity equivalency factor tevent Event duration TRV toxicity reference value USBLM Bureau of Land Management USFWS U.S. Fish and Wildlife Service VF Volatilization factor Waterj Constituent concentration in water WIR Total water ingestion rate for the representative species yd3 cubic yard ES011013043021SEA VII ------- ------- 1. Introduction This Risk assessment Work Plan (RAWP) describes the approach to be used in preparing the baseline risk assessment for the Salt Chuck Mine remedial investigation/feasibility study (RI/FS) being conducted by the U.S. Environmental Protection Agency (EPA) in Tongass National Forest, Alaska. Salt Chuck Mine was added to the EPA National Priorities List on March 4, 2010. The site is an inactive former copper, gold, silver, and platinum group elements (PGEs), most notably palladium mine located on Prince of Wales Island in the Tongass National Forest at the northern end of Kasaan Bay, Alaska (Figure 1). This RAWP meets requirements of the RI/FS Work Plan Amendment 1, Revision 0 for Salt Chuck Mine, Task Order TBD-RI-FS-10GK, Region 10 AES Contract No. 68-S7-04-01, which stipulates that a risk assessment shall be conducted as part of the RI/FS at Salt Chuck Mine, and in accordance with CERCLA. 1.1 Purpose of the Risk Assessment The baseline risk assessment will seek to determine the nature, magnitude, and probability of actual or potential harm to public health, safety, or welfare, or to the environment, posed by the threatened or actual release of hazardous substances. Two components will comprise the risk assessment: a human health risk assessment (HHRA) and an ecological risk assessment (ERA). The assessment will identify and characterize the toxicity of chemicals of potential concern (COPCs), potential exposure pathways, potential human and ecological receptors, and the likelihood and extent of impact or threat under current and reasonably anticipated future land use conditions at the site. The results of the risk assessment will provide, with consideration of other factors, a basis for risk management decisions. Based on the magnitude of risks posed by the site, the overall objective of the risk assessment will be to identify which one of three decisions is most appropriate: (1) proceed with an evaluation of remedial options; (2) proceed with a No Further Action determination; or (3) acquire additional site characterization data to address residual uncertainties and further refine the conceptual site model (CSM) and risk assessment. 1.2 Organization of this Work Plan This RAWP includes the following components: • Section 1, Introduction. Provides the objectives of the risk assessment and organization of the RAWP. • Section 2, Conceptual Site Model. Describes the site characteristics and history, hydrology, ecological setting, and land and water uses, and identifies the pathways by which human and ecological exposures could occur. • Section 3, Data Usability and Processing. Describes the process for evaluating data usability for the risk assessment. • Section 4, Human Health Risk Assessment Methodology. Provides the approach that will be used for the human exposure assessment, toxicity assessment, and risk characterization. • Section 5, Ecological Risk Assessment Methodology. Provides the approach that will be used to evaluate ecological exposures and effects, and forcharacterizing risk to ecological receptors. • Section 6, Risk Assessment Report. Describes the report containing the HHRA and ERA • Section 7, References. Provides citations from this RAWP ES011013043021SEA ------- ------- mmm Unnamed Island i. t «med Strea/tt Salt Chuck Bay Gosti Island r'fip fe-s*' Lake Ellen f' Browns Lt* iSBtf WWPjC** fff. k \ \ CANAL J \ ALASKA ^ ^JSalt Chuck Mine streams/Creek Mine Waste Type 100-foot Contour Line (TNF) Glory Hole Waste Rock Piie Waste Rock Pile and Tailings Tailings 2,000 I 4,000 Feet J Notes: (1) Aerial photography courtesy US Census Bureau; approximate date 2006. NAD83, UTM Zone 8N, Meters. Pixel size 1 meter. (2) Source Documents: Figures 2-2 and 2-3, URS, Salt Chuck Mine Report, March 2010. Features: C-Series, D-Series, Mean High Tide, Stream, with modifications based on site observations from 2012 Rl investigation. (3) TNF = Tongass National Forest Figure 1 Location and Site Features Risk Assessment Work Plan Salt Chuck Mine, Alaska SER* ------- ------- 2. Conceptual Site Model This section describes the potential exposure pathways for contaminants believed to be potentially associated with the Salt Chuck Mine, based on currently available site information. The CSM is formulated according to applicable guidance, with the use of professional judgment and site-specific information on contaminant sources, release mechanisms, routes of migration, potential exposure points, potential routes of exposure, and potential receptor groups associated with the site. The CSM provides a framework for understanding conditions and physical processes which influence the potential for risk. The CSM describes the following: • Sources of chemicals of potential concern. • Pathways describing the physical mechanism through which a chemical could come into contact with receptors (i.e., potentially exposed humans or wildlife). • Receptors comprised of human or ecological populations potentially exposed to the chemicals of potential concern. There must be a complete exposure pathway from the source of chemicals in the environment (in soil, groundwater, air, sediment, surface water, or biota) to human or ecological receptors forchemical intake to occur. In the absence of any one of these components, an exposure pathway is considered incomplete and by definition, there is no risk or hazard. Preliminary human health and ecological conceptual exposure models for Salt Chuck Mine were originally presented in Figures 2-9 and 2-10 in the Draft Quality Assurance Project Plan Salt Chuck Mine Remedial Investigation, Tongass National Forest, Alaska (CH2M HILL, 2012a). These exposure models have been updated to reflect current understanding of sources, pathways, and receptors at the Salt Chuck Mine site, which are described below. 2.1 Site Description Salt Chuck Mine is located approximately 4Vz miles south-southwest of Thorne Bay, Alaska, at the northern end of Kasaan Bay, on Prince of Wales Island (Figure 1). The mine is located in the Tongass National Forest, Outer Ketchikan County, within Township 72 South, Range 84 East, Sections 16 and 17, Copper River Meridian, Alaska. Salt Chuck Bay, from which the mine takes its name, is a shallow, restricted water body bordering the mine site to the south and forms the northernmost arm of Kasaan Bay (Figure 1). The Salt Chuck Mine site is accessible by water or by road, the last ^-mile of which is newly constructed and remains gated. Thorne Bay (population 471) is the closest year-around population, and is accessible from the site by road. The Organized Village of Kasaan (Kasaan, population 49) is the nearest community by water and is located about 9 miles southeast of the site on the eastern side of Kasaan Bay. For the purposes of the Rl,the Salt Chuck Mine site includes both the upland areas that lie on lands managed by the United States Department of Agriculture, Forest Service (Forest Service) and those adjacent areas and impacted environments within State-owned tidelands (referred to as the intertidaI zone in this RAWP). The upland area includes the former mill site and associated features (former buildings, above-ground storage tank, drum storage area, electric locomotive batteries, etc.) as well as other mine-related features not directly at the mill site (upland tailings piles, waste rock piles, tramways, adit, glory hole, etc). The upland area consists of remnants of at least 25 structures and 13 waste rock piles and two main tailing deposits. Remains of buildings and waste rock piles are located near the beach, along the tramway leading from an adit to the mill, upstream along the unnamed stream that flows past the adit portal, and near the glory hole. The mine openings are uphill and approximately ^-mile from the mill area. Part of the west side of the Salt Chuck Mine upland area is bordered by Lake Ellen Creek, which originates from Lake Ellen located west of the site. The intertida I zone, as defined by the area below mean high tide, encompasses approximately 80 acres south of the mill site, and extends around an unnamed island in the middle of Salt Chuck Bay. Much of the intertida I zone is ES011013043021SEA 2-1 ------- 2 CONCEPTUAL SITE MODEL covered by fucus, gravel, mollusk shell fragments, and beach grasses, but areas closest to the former mill site consist of mud flats mixed with tailings, with little vegetation. The main tailings pile is comprised of roughly 100.000 cubic yards (yd3) of material located primarily in the intertida I zone south and southeast of the mill. This main tailing pile and the adjacent upland tailings deposits, together cover an area of approximately 23 acres. The saturated intertida I tailings are not contained in a manner that prevents contaminants within the tailings from migrating into the waters of Salt Chuck Bay. 2.1.1 History The first claims at Salt Chuck Mine were staked in 1905, when the mine was originally was known as the Goodro Mine (Bureau of Land Management [BLM], 1998). The mine and mill operated from 1905 to 1941 and processed over 326,000 tons of ore. The primary ores produced from the mine were copper, gold, silver, and platinum group elements, most notably palladium. Salt Chuck Mine was the most important copper producer in the Ketchikan Mining District, the only single lode palladium mine in Alaska, and of national importance as a palladium producer in the 1920s. The discovery that the ore contained palladium/platinum led to construction of the mill with a capacity of processing 30 tons of ore per day in 1917, and expanded to a capacity of 300 tons per day in 1923. Considerable historic mining activity has occurred in the mineral-rich region where the Salt Chuck Mine site is located (Maas et al., 1995). Nearby historic mines include the Rush and Brown Mine located on the west slope of Lake Ellen, the Venus Mine located about 1-1/2 miles southwest of the site, in an area that drains southward into Karta Bay, and the Haida Mine located northeast of Browns Bay about 2-1/2 miles southeast of the site. Pure Nickel, Inc. currently holds active mining claims covering about 2,700 acres at and near the Salt Chuck Mine site. 2.1.2 Climate Climatological data recorded by the National Oceanic and Atmospheric Administration (NOAA) at the weather station in Craig (about 25 miles southeast of the mine site) indicates that the annual precipitation in that area was 84, 94, and 105 inches in 2009, 2010, and 2011, respectively. The climate summary for Craig is provided in Table 1. The rainy season occurs in fall and early winter (NOAA National Climate Data Center, 2012). Of this, up to about 25 inches of snow fall per year. The average annual temperature is about 45 degrees Fahrenheit (°F). July and August are the warmest months, with average high temperatures in the upper-50s (°F), and January and February are typically the coldest months, with average low temperatures in the upper-30s (°F). In 2009, there were 97 days with reported temperatures below freezing. Daylight changes from 15 Vz hours on the longest day of the year to about 7 hours on the shortest. It should be noted that the Thorne Bay side of the island where the mine site is gets appreciably more precipitation than the Craig side. 2.2 Site Hydrology Surface water flows from the upland portion of the Salt Chuck Mine site include those from the main adit, a small unnamed stream, and Lake Ellen Creek (Figure 1). Water also discharges from shallow groundwater originating from the upland mine areas and the former mill site. Salt Chuck Bay is the ultimate receiving body forall of these flows. 2.2.1 Adit Discharge Surface water runoff in the upper portion of the Salt Chuck Mine site enters the glory hole at the 300-foot elevation and drains into the haulage level of the main adit. The discharge from the main adit portal is believed to result when water collecting within the glory hole mixes with groundwater percolating through bedrock fractures, collects behind rock and debris near the adit portal, then discharges from the portal at an estimated flow rate of <0.1 cubic feet per second (cfs) (URS, 2007). 2.2.2 Unnamed Stream A small, unnamed stream (Unnamed Stream), originating northeast of the site from Power Lake cuts across the upland areas of Salt Chuck mine and also receives discharge from the adit. During higher flow events, overflows near the adit portal flow both west down the normal drainage and south along the rail line. The rail line overflow diverges from the track after approximately 100 feet then flows westerly, rejoining the Unnamed Stream. The 2-2 ES011013043021SEA ------- 2 CONCEPTUAL SITE MODEL Unnamed Stream continues to flow south and discharges into the head of Salt Chuck Bay about 300 feet west of the former mill site. The flow rate ranges from less than 1 to about 10 cfs in the stream, varying directly with precipitation conditions. Wetland areas exist along the entire length of the stream. Once discharging into the intertidaI area, at low tide the Unnamed Stream continues to flow along the west side of the tailings pile and merges with the Lake Ellen Creek before entering Salt Chuck Bay. 2.2.3 Lake Ellen Creek Lake Ellen Creek originates from Lake Ellen 0.5 miles west of the mine site, flowing around the western portion of the mine site then into Salt Chuck Bay. At low tide, Lake Ellen Creek merges with the unnamed stream southwest of the tailings pile before entering Salt Chuck Bay (Figure 1). Estimated average flow in Lake Ellen Creek is approximately 15 to 20 cfs, based upon observations made by BLM personnel during the 1997 Removal Preliminary Assessment (BLM, 1998). 2.2.4 Salt Chuck Bay An intertida I zone encompassing approximately 80 acres is located south of the mill site, and extends around an unnamed island in the middle of Salt Chuck Bay (Figure 1). At high tide, saltwater from Salt Chuck Bay inundates the lower portions of Lake Ellen Creek, the unnamed stream, and the main tailings pile. The streams, tailings, and outlying sediment are exposed at low tide. Maximum tidal ranges in the Kasaan Bay area are typically on the order of 18 to 23 feet (NOAA, 2002). At highest high tides, saltwater is expected to be on the order of 3 to 9 feet above the seafloor near the mouth of Lake Ellen Creek. The bench that the mill sits on is roughly 6 to 10 feet above the highest tide line. 2.3 Ecological Setting The Kasaan Peninsula is a long mountainous ridge with steep, heavily timbered slopes. The upland area of the Salt Chuck Mine site is characterized by gently rolling hills, dense vegetation, and bedrock (BLM, 1998). The habitat consists of wet coastal rain forest common to Southeast Alaska. Vegetation is typical of Southeast Alaska where forested areas are dominated by Sitka spruce (Picea sitchensis) and western hemlock (Tsuga heterophylla), with some western red cedar (Thuja plicata), yellow cedar (Chamaecyparis nootkatensis), shore pine (Pinus contorta), and alder (Alnus rubra) intermixed with abundant berry bushes, devil's club, and small scrub shrubs. Species of plants, invertebrates, fish, birds, and mammals common to Southeast Alaska and which may be present in the site area are listed in Tables 2 through 5. 2.3.1 Wetlands Figure 2 shows the locations of wetland area in the general vicinity of the Salt Chuck mine site, as identified by the US Fish and Wildlife Service National Wetlands Inventory (USFWS, 2012). Lake Ellen Creek is classified as riverine, tidal, with an unconsolidated bottom and permanent tidal wetland. The higher beach areas are classified as estuarine intertida I, emergent, and persist in a tidal regime that is irregularly flooded. The intertida I area is classified as regularly flooded, with sand and gravel flats and aquatic beds-algae (BLM, 1998). Freshwater forested wetland areas are present along the entire length of the Unnamed Stream that bisects the mine site (Figure 1). 2.3.2 Aquatic Life Lake Ellen Creek is considered an anadromous fish stream that may support pink, coho, and chum salmon, dolly varden, and steelhead (BLM, 1998). During low tide, several salmon were also observed in the lower portion of the Unnamed Creek adjacent to the intertida I tailings pile, during the 2011 sampling event. According to the Alaska Department of Natural Resources (ADNR), Karta Bay and Salt Chuck Bay are unique areas with high fish and wildlife habitat and harvest values and recreation values. Karta Bay, adjacent and downstream to Salt Chuck Bay, is an important community sockeye salmon harvest area (ADNR, 1998). ES011013043021SEA 2-3 ------- US, 1 JKIMM .V W ItJll.ll'i: service U.S. Fish and Wildlife Service National Wetlands Inventoi Wetlands Near Salt Chuck Mine Wetlands Freshwater Emergent Freshwater Forested/Shrub Estuarineand Marine Deepwater Estuarineand Marine Freshwater Pond Lake Riverine Other This map is for general reference only. The US Fish and Wildlife Service is not responsible for the accuracy or currentness of the base data shown on this map. All wetlands related data should be used in accordance with the layer metadata found on the Wetlands Mapper web site. Source: US Fish and Wildlife Service Wetlands Mapper, October 3, 2012 ES010913033811PDX EPA_RAWP_Fig2_NationalWetlands LW 1.09.13 FIGURE 2 National Wetlands Inventory Map Salt Chuck Mine Remedial Investigation Risk Assessment Work Plan CH2MHILL. PF04B E2AB1/USN PF04B ------- 2 CONCEPTUAL SITE MODEL The intertidaI areas within Salt Chuck Bay support an abundance of shellfish and contain a diverse assemblage of seaweeds and marine invertebrates, including blue mussels, little neck clams, softshell clams, butter clams, cockles, barnacles, snails, shrimp, starfish, and crabs. Lower invertebrate diversity is seen closer to the Salt Chuck Mine site in the southern part of the intertida I tailings deposit, which supports a significant population of marine worms, but is almost devoid of shellfish. Kasaan Bay, located downstream from Salt Chuck Bay and Karta Bay, supports abundant fish and wildlife. Several areas along the west side of Kasaan Bay, downstream of Karta Bay are classified as crucial habitat for herring spawning and salmon rearing and schooling. Twelvemile Arm flows southwest from the upper portion of Kasaan Bay and supports several anadromous fish streams designated as crucial habitat for salmon rearing and schooling. 2.3.3 Wildlife ADNR designates Salt Chuck and Karta Bays as Crucial Habitat (Ha) for seasonal black bear concentrations, seasonal waterfowl concentrations, herring spawning, and salmon rearing and schooling (ADNR, 1998). Sitka black- tailed deer, black bear, wolf, and mink tracks were observed on the intertida I tailings area south of the Salt Chuck Mine site during the 2011 and 2012 investigation activities. Numerous species of birds were also observed both along the shoreline and in the rainforest canopy, including seabirds (e.g., cormorants), shore birds (e.g., sandpipers), bald eagles, belted kingfishers, ravens, waterfowl (e.g., Canada geese), and a variety of passerines (e.g., chickadees). Species of birds and mammals common to Southeast Alaska that may occur on Prince of Wales Island are listed in Tables 4 and 5. 2.3.4 Threatened and Endangered Species No designated habitat for Threatened and Endangered Species (T&E) has been identified at the site, and no sensitive environmental areas have been designated by the Alaska Coastal Management Program near the site (BLM, 1998). The only federally designated T&E species visiting the Prince of Wales Island area is the humpback whale (BLM, 1998). The humpback whale is a transient visitor to the general area, as is the Steller sea lion. There are no designated sea lion haulouts near Karta Bay. 2.4 Current and Reasonably Anticipated Land Uses Current and reasonably anticipated future land uses are used to identify potentially exposed populations and to determine exposure patterns for the environmental media at the site, including soil, groundwater, air, sediment, surface water, or biota. The land use status for the lands on and surrounding the Salt Chuck Mine site are shown on Figure 3. The Salt Chuck Mine area is designated as an undeveloped area of intensive public recreation use by the Alaska Department of Natural Resources (ADNR, 1998) Prince of Wales Island Area Plan. Salt Chuck Bay is an excellent protected waterway for canoes, kayaks, and other small boats, and passage from Salt Chuck Bay to Lake Ellen is possible by these smaller watercraft during high flows and tides. The Salt Chuck Mine site in general is accessible by road (via Forest Service locked gate), trail, boat, of float plane. Forest service roads extend past the north end of the mine site, and are used by hunters and casual recreational vehicle traffic. There is a marked trailhead located along the Forest Service road about 0.5 miles north of the glory hole. This hiking trail extends 1.1 mile along the banks of Ellen Creek down to the mouth of the Unnamed Stream and to the former mill site. Recreational users include hunters, hikers, boaters, anglers, rock climbers, gatherers (e.g., berry, mushroom, and sea asparagus pickers), clam diggers, trappers, etc. The glory hole at the Salt Chuck Mine is known to be used by rock climbers forrappelling. A Forest Service campground is located about 1.2 miles northwest of the site at Lake No.3. In addition, a recreational public cabin is located on Forest Service land at the mouth of the Karta River about five miles south of the site. The nearest public access boat ramp to the site is located in Kasaan, about 10 miles southeast of the site. Although there are no dock facilities at the mine site, the upper end of Salt Chuck Bay is accessible during high tide by small craft. However, the road system and trail extending from the glory hole to the mill make access by land the most common access. ES011013043021SEA 2-5 ------- See SJubunit HcJnset Maps es on Following Pa a Lake No Chuck Mine Salt Chi^ck ya wn Mfrte Ru Lake Ellen Coppei Center be ke U \ Chuck °ung LEGEND State Owned Mental Health Municipal Private Tongass National Forest Re-open to Mineral Entry Closed to Mineral Entry A Cabin A Anadromous Fish Stream ^ Anadromous Stream Closed to Mineral Entry ^ Mine Subunit Boundary Ha Cy Ru S m Crucial Habitat Important Community Harvest Public Recreation - Undeveloped Settlement Mineral Access Source: Alaska Department of Natural Resources, Division of Mining, Land, and Water, 1998. Prince of Wales Island Area Plan, 1998. Originally adopted June 1985; revised October 1998. ES010913033811PDX EPA_RAWP_Fig3_Land Use Status LW 1.10.13 FIGURE 3 Land Use Status in the Vicinity of Salt Chuck Mine Salt Chuck Mine Remedial Investigation Risk Assessment Work Plan CH2MHILL. ------- FIGURE 4 Conceptual Site Model for Potential Human Exposures for the Intertidal Areas Remedial Investigation, Salt Chuck Mine, Tongass National Forest, Alaska Risk Assessment Work Plan Elements of a Complete Exposure Pathway Potential Receptors tidal flux Mine Adits and Seeps Historic Mining Operations Intertidal Areas in Salt Chuck Bay Lake Ellen Creek and Unnamed Creek Ingestion of Fish and Shellfish Erosion Ingestion of Intertidal Plants Ingestion of Fish and Shellfish Incidental Ingestion Ingestion of Intertidal Plants Surface Water Intertidal Areas in Salt Chuck Bay Direct Discharge Lake Ellen Creek and Unnamed Creek Surface Runoff Sediment Leaching Sediment Biota Intertidal Area Mine Tailings Dermal Contact Dermal Contact Infiltration/Percolation and Leaching Aquatic Biota Upland Mine Tailings Incidental Ingestion Potential Exposure Points Transport/Exposure Media Historical General Sources of Contamination Potential Exposure Routes Chemical Release Mechanisms Notes: ¦ = .Potentially complete patnway U = Patnway considered minor Blank = Incomplete pathway a. This scenario generally addresses individuals who include natural food sources in their diet, either in part or in total, by hunting, fishing, and/or gathering native food for consumption. b. Includes aboveground fuel storage tanks, battery banks, and other upland sources associated with historic mining operations. ------- FIGURE 5 Conceptual Site Model for Potential Human Exposures for the Upland Areas Remedial Investigation, Salt Chuck Mine, Tongass National Forest, Alaska Risk Assessment Work Plan Elements of a Complete Exposure Pathway Potential Receptors Direct contact by receptors flux Dermal Contact Sediment Surface Water Incidental Ingestion Lake Ellen Creek Dermal Contact Surface Runoff Unnamed Creek Unnamed Creek Dermal Contact Incidental Ingestion Groundwater Upland Biota Direct Discharge Ingestion of Wild Game Upland Waste Rock Piles Infiltration/Percolation and Leaching Mine Adits and Seeps Lake Ellen Creek Upland Soil Fugitive Dust Emission Dust Inhalation Onsite Upland Areas Historic Mining Operations Decomposition/ Weathering/ Erosion Upland Mine Tailings Incidental Ingestion Ingestion of Wild Plants Historical General Sources of Contamination Chemical Release Mechanisms T ransport/Exposure Media Potential Exposure Points Potential Exposure Routes Notes: ¦ = potentially complete pamway U = Fatnway considered minor Blank = Incomplete pathway a. This scenario generally addresses individuals who include natural food sources in their diet, either in part or in total, by hunting, fishing, and/or gathering native food for consumption. b. Includes aboveground fuel storage tanks, battery banks, and other upland sources associated with historic mining operations. ------- FIGURE 6 Conceptual Site Model for Potential Ecological Exposures for the Intertidal Areas Remedial Investigation, Salt Chuck Mine, Tongass National Forest, Alaska Risk Assessment Work Plan Elements of a Complete Exposure Pathway Historical General Sources of Contamination Chemical Release Mechanisms T ransport/Exposure Media Potential Exposure Points Potential Exposure Routes Potential Receptors CO > CO > =; & & W* 8- S- P a o O o & o < £ CTQ cr 0) CTQ R B P 3 =r o' O =r CTQ < B 3- XA CT" P Upland Mine Tailings Historic Mining Operations' Mine Adits and Seeps Intertidal Area Mine Tailings Infiltration/Percolation and Leaching ^ Surface Runoff Direct Discharge Erosion Leaching Aquatic Biota Surface Water tidal flux Sediment Sediment Biota Lake Ellen Creek and Unnamed Creek Intertidal Areas in Salt Chuck Bay Lake Ellen Creek and Unnamed Creek Intertidal Areas in Salt Chuck Bay Incidental Ingestion Dermal Contact Ingestion of Intertidal Plants Ingestion of Fish and Shellfish Incidental Ingestion Dermal Contact Ingestion of Intertidal Plants Ingestion of Fish and Shellfish ¦ ~ ¦ ¦ ¦ ¦ ¦ ~ ~ ¦ ¦ ¦ ¦ ¦ Notes: ¦ = Potentially complete pathway ~ = Pathway considered minor Blank = Incomplete pathway a. Includes aboveground fuel storage tanks, battery banks, and other upland sources associated with historic mining operations. ------- FIGURE 7 Conceptual Site Model for Potential Human Exposures for the Upland Areas Remedial Investigation, Salt Chuck Mine, Tongass National Forest, Alaska Risk Assessment Work Plan Elements of a Complete Exposure Pathway Historical General Sources of Contamination Chemical Release Mechanisms Transport/Exposure Media Potential Exposure Points Potential Exposure Routes Potential Receptors 03 H H & d d 1 § & B. sa S I < s £. o* £ 1. 3 3 » P- '4 S* £ Upland Mine T ailings Upland Waste Rock Piles Mine Adits and Seeps Historic Mining Operationsa Decomposition/ Weathering/ Erosion Fugitive Dust Emission Direct contact by receptors Infiltration/Percolation and Leaching Surface Runoff Direct Discharge Upland Soil Upland Biota Surface Water Onsite Upland Areas Lake Ellen Creek Unnamed Creek Lake Ellen Creek Unnamed Creek Incidental Ingestion Dermal Contact Dust Inhalation Ingestion of Upland Plants Ingestion of Upland Prey Incidental Ingestion Dermal Contact Direct Uptake (e.g. gills) Bioaccumulation into Foodweb Incidental Ingestion Dermal Contact Direct Uptake (e.g. gills) Bioaccumulation into Foodweb ¦ ~ ~ ~ ¦ ¦ ¦ ¦ ~ ¦ ¦ ¦ ~ ¦ ¦ Notes: ¦ = Potentially complete patnway ~ = Patnway considered minor Blank = Incomplete pathway a. Includes aboveground fuel storage tanks, battery banks, and other upland sources associated with historic mining operations. ------- 2 CONCEPTUAL SITE MODEL According to the ADNR (1998) plan, the Salt Chuck Mine falls within Land Management Subunit lib (Karta Bay), which is designated as having high fish and wildlife habitat and harvest values. The Salt Chuck area is designated for Intensive Community Use (Cy) for harvest of clams, crab, oysters, waterfowl, and black bear by residents of Kasaan, Hollis, and Craig, as well as Recreation-undeveloped (Ru) (Figure 3; ADNR, 1998). Visitors may also collect berries, mushrooms, and sea asparagus [also known aspickleweed orglasswort (Salicornia spp.)] from the area. The closest of the communities, Kasaan, is located about 10 miles southeast of Salt Chuck Mine along the eastern shore of Kasaan Bay. The native Village of Kasaan utilizes Salt Chuck Bay for cultural and traditional uses, including fishing. 2.5 Water Uses 2.5.1 Surface Water The surface water uses generally recognized for Salt Chuck Bay include fishing, shellfish harvesting, boating, water recreation, wildlife watching, aesthetic quality, salmonid fish rearing and migration, and growth, propagation and habitat for resident fish, aquatic life, and wildlife. There are no known drinking sources of surface water in the vicinity of the Salt Chuck Mine site. 2.5.2 Groundwater Shallow groundwater occurs intermittently and seasonally just below surface soils in upland areas of the site. Groundwater is found to be very shallow in the area due to the presence of bedrock and thin soils, and migration could potentially occur along a bedrock/soil interface. When present, the depth to groundwater ranges from about 1 to 4 feet below ground surface (bgs). During low tide, a seep is visible in the intertidaI flat immediately below the former mill site, and likely represents a groundwater pathway connection to intertida I zone receptors. Six groundwater monitoring wells were installed at the Salt Chuck Mill site in 2011; three in the upland tailing vicinity and three near other source areas in the former mill site. Groundwater ingestion is not considered to be a pathway of concern for humans because there are no drinking water wells within a 15-mile target distance hydrologically downgradient of the Salt Chuck Mine site (BLM, 1998). Given the proximity of the lower portion of the site to marine and estuarine water, it is likely that groundwater in this area is not potable and would not be used for drinking water in the future. Any plausible access to potable groundwater would require drilling through the bedrock. However, groundwater in the upland area is unlikely to be developed for drinking water in the future, due to the presence of more readily available surface water sources, and low yields in bedrock aquifers. 2.6 Conceptual Exposure Model Figures 4 and 5 show the conceptual exposure models for human exposure pathways in the intertida I and upland areas, respectively. Figures 6 and 7 show the conceptual exposure models for ecological exposure pathways in the intertida I and upland areas, respectively. The potential exposure pathways at Salt Chuck Mine and are discussed below. 2.6.1 Sources The assessment of sources is based on known historical uses, practices, and releases at Salt Chuck Mine. The primary sources of contaminants and release mechanisms include those associated with former operations at various locations. These primary and secondary sources include the following: • Mine tailings deposited onto upland and intertida I areas • Historical mining operations, including aboveground fuel storage tanks, battery banks, and other upland sources of petroleum and PAHs • Upland waste rock from mine shafts and open-pit mining ES011013043021SEA 2-7 ------- 2 CONCEPTUAL SITE MODEL • Historical aerial releases of dust from former mill operations • Water from mine adits and seeps • Water and sediments in the water bodies at and near the mine site 2.6.2 Release Mechanisms and Potential Transport Media Exposure may occur when chemicals migrate from their source to an exposure point (i.e., a location where individuals or organisms can come into contact with the chemicals) or when a receptor moves into direct contact with chemicals or contaminated media connected to the source. An exposure pathway is complete (i.e., there is exposure) if there is a means for the receptor to take in chemicals through ingestion, inhalation, or dermal absorption at a location where site-related chemicals are present. No exposure (and therefore no risk) exists unless the exposure pathway is complete. The exposure/risk linkage is an important element in the risk assessment process. The CSM identifies the following mechanisms that could transport site-related constituents to environmental media: • Decomposition, weathering, and erosion of contaminants from tailings and waste rock • Leaching, percolation and infiltration of contaminants to shallow groundwater • Surface discharge and seepage of shallow groundwater contaminated by contact with waste rock or tailings, or by flowing through underground workings • Transport of dissolved or particulate contaminants in surface runoff to surface water and sediment in nearby water bodies • Dust generated from wind or mechanical erosion on contaminated surface soils at the mine site. This migration pathway is considered minimal due to general wet climates and moss covering on the forest floor. Receptors could be exposed by contaminant migration from the original release areas to potential exposure points or by direct contact with contaminated tailings, waste rock, or other media at the mine site. Based on past site investigations, the general types of site-related contaminants identified include: • Metals—at both upland and intertidaI areas • Polynuclear aromatic hydrocarbons (PAHs)— at both upland and intertida I areas • Petroleum hydrocarbons—at both upland and intertida I areas 2.6.3 Potentially Complete Human Exposure Pathways and Receptors On the basis of the current understanding of land and water use conditions at or near the Salt Chuck Mine site, the most plausible current or future human receptor populations include the following: • Recreational visitors and recreational users (e.g., hikers, clam diggers) • Customary and traditional users (e.g., hunters, anglers, clam diggers, gatherers)1 • Intermittent workers (e.g., foresters, prospectors, etc.) For these potentially exposed populations, the most plausible exposure routes that will be considered for characterizing human health risks include the following: • Incidental ingestion of, dermal contact with, and inhalation of dust from surface soil, by recreational users, customary/traditional users, and intermittent workers 1 For the purposes of this RAWP, the term "customary and traditional user" specifically refers to local Alaska Natives who incl ude natural food sources in their diet, either in part or in total, by hunting, fishing, and/or gathering native food for consumption. The results for this exposure scenario will also be applicable to "subsistence" users as defined in Title VIII of the Alaska National Interest Lands Conservation Act (ANILCA), including homesteaders or other non-Native people living in remote locations and exercisingthetraditional practice of living off the land. 2-12 ES011013043021SEA ------- 2 CONCEPTUAL SITE MODEL • Incidental ingestion of and dermal contact with surface water and sediment by recreational users and customary/traditional users • Consumption of shellfish and fish that have accumulated mine-related COPCs, by recreational users and customary/traditional users • Consumption of wild game that has accumulated mine-related COPCs, by recreational users and customary/traditional users • Consumption of upland and intertidaI plants that have accumulated mine-related COPCs, by recreational users and customary/traditional users Due to the remoteness, and high recreational value of the Salt Chuck Mine site, future residential development is unlikely; consequently, potential future residential scenarios will not be evaluated. Moreover, mining features and artifacts present throughout the site are eligible for National Register listing under the National Historic Preservation Act (NHPA) of 1966 (URS, 2010). 2.6.4 Potentially Complete Ecological Exposure Pathways and Receptors In accordance with the CSM, plausible ecological exposure pathways that are based on the contaminant types, available habitat, and available food sources at the Salt Chuck Mine site include the following: • Potential exposure of upland wildlife by direct contact with mine-related COPCs in soil (including incidental ingestion of soil by birds and mammals during foraging activities) • Potential exposure of upland and intertida I wildlife by direct contact with mine-related COPCs in surface water and sediment • Potential ingestion of mine-related COPCs via the food chain by higher trophic level upland and intertida I wildlife that may forage in the habitats at the site • Potential exposure of aquatic and benthic resources (freshwater and marine fish, invertebrates, and amphibians) to mine-related COPCs present in surface water, sediment, forage, and prey • Potential exposure of upland and intertida I plants to mine-related COPCs present in soil, sediment, and water ES011013043021SEA 2-13 ------- ------- 3. Data Usability and Processing 3.1 Data Usability Analytical data obtained from the 2011, 2012, and 2013 Rl at Salt Chuck Mine will be used in the HHRA and ERA. To determine whether the available analytical data are suitable for use in the risk assessment, a data usability evaluation will be performed consistent with Risk Assessment Guidance for Superfund (RAGS) (EPA, 1989). This determination will be based upon two lines of evaluation: 1. Identification of the adequacy of method detection limits (MDLs) for available analytical data to detect potential risks posed by the Salt Chuck Mine. 2. Evaluation of the spatial, chemical, and temporal representativeness of the available analytical data, and an assessment of whether these data are relevant to plausible exposure pathways at the Salt Chuck Mine. MDLs for available analytical data will be compared to risk-based screening criteria (for example, EPA Regional Screening Levels, EPA, 2012a). If MDLsforthe available data exceed these risk-based criteria, and are above reporting limits that are achievable using standard EPA methods, then the data may be considered inadequate for use. In addition to evaluating MDLs, the available analytical data will also be evaluated to determine whether they are representative of potential exposures possible the Salt Chuck Mine site. The criteria for data representativeness are defined below: • Chemical representativeness - Identifies whether analyses were conducted for constituents expected to be present, on the basis of an understanding of historical processes or practices and potential releases at the site. • Exposure representativeness - Identifies whether environmental media were evaluated where receptor exposure is most feasible (for example, surface soil sampling locations, dissolved versus total metals, etc). • Spatial representativeness - Identifies whether samples were collected with a sufficient density and areal coverage that the detected constituent concentrations represent a geographically-integrated exposure forthe receptors of concern. • Temporal representativeness - Identifies whether samples were collected within a time frame such that detected constituent concentrations indicate current site conditions. These criteria will be considered collectively during data evaluation to judge whether site data are useable for risk assessment purposes, and to identify any associated uncertainties to be reported in the uncertainties section of the risk assessment report. 3.2 Data Processing Procedures Prior to use in the risk assessment, laboratory analytical data will be processed so that only reliable data are included. The data processing will be consistent with RAGS (EPA, 1989) and consist of the following checks: • Estimated values flagged with a "J" qualifier will be treated as qualified detected concentrations. • Data for detected constituents that are also detected in method blanks will not be used in the risk assessment. • For duplicate samples, the following procedure will be applied: (a) if there are two detections, the maximum value will be used; (b) if there is one detection and one nondetection, the detected value will be used; (c) if there are two nondetections, the lowest detection limit will be used. • Data qualified with an "R" (rejected) will not be used in the risk assessment and not included in the total count of samples analyzed for a constituent. ES011013043021SEA 3-1 ------- ------- 4. Human Health Risk Assessment Methodology The baseline HHRA will present an analysis of the potential foradverse human health effects potentially associated with chemical releases at the Salt Chuck Mine. U.S. EPA and Alaska DEC guidance for preparing HHRAs will be consulted in the development of the human health risk evaluation. 4.1 Human Health Risk Assessment Guidance The procedures described in this Work Plan are consistent with those described in following federal and state guidance documents: • Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation ManualPart A (Interim Final) (EPA, 1989) • Risk Assessment Guidance for Superfund, Volume 1: Human Health Evaluation Manual. Supplemental Guidance: Standard Default Exposure Factors (EPA, 1991a) • Soil Screening Guidance: Users Guide, Second Edition (EPA, 1996a) • Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment, Final) (EPA, 2004) • Guidelines for Carcinogen Risk Assessment. (EPA, 2005) • Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation Manual (Part F, Supplemental Guidance for Inhalation Risk Assessment) (EPA, 2009a) • ProUCL Version 4.1.00 Technical Guide (EPA, 2010a) • Exposure Factors Handbook (EPA, 2011a) • Risk Assessment Procedures Manual (Draft) (ADEC, 2011) 4.2 Identification of Chemicals of Potential Concern for Human Health COPCs are those constituents that are carried through the human health risk quantification process. During the course of the HHRA, the COPCs will be evaluated to identify and prioritize which constituents, if any, are estimated to pose unacceptable risks and therefore may need to be addressed during a Feasibility Study. Historical investigations at the Salt Chuck Mine site have focused the general constituent types that have been released to site media of concern. These previous site investigations are documented in the Final Report, Removal Preliminary Assessment, Salt Chuck Mine, Ketchikan Ranger District, Tongass National Forest, Region 10 - Alaska (BLM 1998), Draft Report Engineering Evaluation/Cost Analysis, Salt Chuck Mine Tongass National Forest, Alaska (Draft EE/CA) (URS 2007), Final Completion Report Non-Time Critical Removal Action Salt Chuck Mine Mill Prince of Wales Island, Alaska (North Wind, 2012), Preliminary Findings for Pre-RI 2011 Field Sampling Activities Technical Memorandum (CH2M HILL, 2012b), and the Salt Chuck Mine - Preliminary Findings for Remedial Investigation 2012 Field Sampling Activities (CH2M HILL, 2013). Based on these past site investigations, the general types of site-related contaminants identified include: • Metals-at both upland and intertidaI areas • PAHs-at both upland and intertida I areas • Petroleum hydrocarbons-at both upland and intertida I areas Since the general area was historically mined because the soil is rich in minerals and metals, the inorganic COPCs that will be identified for site media of concern will include constituents that also occur naturally. In areas of past mining activity the availability of and potential for these constituents to adversely affect human health and the ES011013043021SEA 4-1 ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY environment may have been increased for several reasons, including changes in the topography and hydrology of the mine area that can result in increased erosion, surface water runoff, and sediment transport to downstream areas as well as geochemical changes in the metals or other parameters (e.g., pH). It is possible that some metals occur at levels above risk-based screening criteria in site and/or background areas. Consistent with EPA policy (EPA, 2002a), no COPC will be eliminated based on comparison to background concentrations. Instead, potential risks and hazards from both site and background (or reference) areas will be characterized, as described in Section 4.5.4. 4.2.1 COPC Selection Process With consideration of the data usability conclusions (per Section 3) and in accordance with EPA guidance, the following factors will be considered in identifying COPCs: • Identification of detected chemicals • Screening values based on toxicological characteristics of each chemical • Identification of essential nutrients • Availability of toxicity factors COPCs will be identified separately for soil, sediment, surface water, and biota. Evaluation of the risk assessment data using these criteria is discussed in the following sections. 4.2.1.1 Identification of Detected Chemicals All chemicals detected at least once in site media (including estimated detections) will be included as potential COPCs. If a detected constituent is found to be a contributor to risk or hazard, but has a very low detection frequency, the associated uncertainties will be addressed in the uncertainty section of the HHRA. As described in the work planning documents forthe Rl (CH2M HILL, 2012a), the limits of detection used forthe investigations were targeted to meet conservative risk-based analytical goals, so that they would be low enough to determine the presence or absence of unacceptable risk. 4.2.1.2 Comparison with Risk-Based Screening Values Maximum concentrations found in each environmental medium (soil, sediment, water, and biota) will be compared to conservative risk-based screening concentrations to identify chemicals for inclusion into the risk assessment. Screening levels will include EPA Regional Screening Levels (RSLs) forthe most conservative residential use scenario (EPA 2012a), equivalent to a cancer risk of 10~6for carcinogens, and adjusted to a hazard quotient (HQ) equal to 0.1 for noncarcinogens. 4.2.1.3 Identification of Essential Nutrients Essential nutrients are those chemicals considered essential for human nutrition. Recommended daily allowances are developed for essential nutrients to estimate safe and adequate daily dietary intakes (National Academy of Sciences, 2006). Because calcium, magnesium, potassium, and sodium are considered to be naturally occurring essential nutrients and are generally recognized as being of low toxicity, they will be considered for exclusion as COPCs. Other essential nutrients such as chromium, copper, iron, and zinc will be included as COPCs, because these can be toxic if levels are very high. 4.2.1.4 Availability of Toxicity Factors If a human health toxicity value for a constituent is not available from a reliable source (as described in Section 4.4), that constituent cannot be included as a COPC in the risk quantification process. However in some cases where adequate toxicity data are unavailable, structurally similar surrogates can be used for these constituents. For example, the toxicity factors for acenaphthene may be used for acenaphthylene, for which none are available. Those constituents without reliable toxicity factors or a suitable surrogate will be discussed in the uncertainty section ofthe HHRA. 4.3 Human Exposure Assessment The exposure assessment step ofthe HHRA for Salt Chuck mine will include the following activities: 4-2 ES011013043021SEA ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY • Calculation of exposure point concentrations (EPCs) • Development of human exposure assumptions for potentially complete exposure pathways • Calculation of chemical intake for COPCs These activities are discussed in the following subsections. 4.3.1 Estimating Exposure Point Concentrations EPCs are estimated constituent concentrations with which a receptor may come into contact, and are specific to each exposure medium. The EPCs for exposure pathways associated with Salt Chuck Mine will be estimated, where appropriate, by aggregating concentration data from media samples collected over a relevant exposure area. The EPCs for aggregate risk estimation will be calculated by using the best statistical estimate of an upper bound on the average exposure concentrations, in accordance with EPA guidance for statistical analysis of monitoring data (EPA, 1989, 1992a, 2002b). EPA considers the 95 percent upper confidence limit (UCL)on the mean concentration as a conservative upper bound estimate that is not likely to underestimate the mean concentration. EPCs will be calculated for each analyte using EPA's statistical program ProLICL, Version 4.1.01 (EPA, 2011b). This procedure identifies the statistical distribution type (that is, normal, lognormal, or non-parametric) for each constituent within the defined exposure area (the area of interest) and computes the corresponding 95 percent UCLforthe identified distribution type. Generally, at least 8 to 10 samples are needed to compute a meaningful UCL. The maximum detected concentration will be used in place of the 95 percent UCLwhen the calculated 95 percent UCL is greater than the maximum detected value. However, using maximum detected values for EPCs may contribute to overestimation of risk. If a maximum value is used and found to contribute to risk or hazard, the associated uncertainties will be addressed in the uncertainty section of the HHRA. Summary statistics for all site media investigated, including the UCL recommended by ProUCL for each COPC, will be tabulated in the HHRA report. The ProUCL output summaries will also be provided as an attachment. The exposure areas over which investigation data will be aggregated for computation ofUCLswill be determined once the 2013 Rl investigation activities are complete. Due to the geographic scale of the Rl, the spatial representativeness, chemical concentration trends, and numbers of samples will all be considered to decide exposure areas for the risk assessment. For the intertidaI area, the mud flats adjacent to the former mill site will likely represent a single exposure area where recreational or customary/traditional users could be exposed to sediment, water, or biota. Other areas and media with much lower concentrations of mine-related constituents may be addressed using screening approaches, rather than by computing areally-averaged results for exposure areas. 4.3.2 Human Exposure Assumptions The estimation of exposure requires numerous assumptions to describe potential exposure situations. Upper- bound exposure assumptions are used to estimate "reasonable maximum exposure" (RME) conditions to provide a bounding estimate on exposure. The exposure assumptions to be used for the HHRA will be specific to the identified exposure scenarios at Salt Chuck Mine. The scenarios to be evaluated were selected based on the conceptual exposure models for the intertida I and upland areas (Figures 4 and 5) and are consistent with the reasonably anticipated future land uses. Based on the known and anticipated activities at the Salt Chuck Mine site, the following receptors were selected to represent current or potential future use of the site: • Recreational users (e.g., hikers, clam diggers) - adult and child • Customary/traditional users (e.g., hunters, anglers, clam diggers, gatherers) - adult and child • Intermittent workers (e.g., foresters, prospectors, etc.) - adult only 4.3.2.1 Recreational Visitor or Customary/Traditional Users Recreational visitors and customary/traditional users are assumed to visit the site for a portion of the year, for example during the time when berries are ripe or when hunting and angling seasons apply. It is assumed that recreational or customary/traditional users would potentially access the site on foot or by boat. It is also assumed that the recreational or customary/traditional users would consume local plants, hunt game, catch fish, or harvest shellfish from the site. However, only a percentage of total native food consumed by the recreational user or ES011013043021SEA 4-3 ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY customary/traditional user would be gathered specifically from the site2. The most plausible exposure routes for recreational or customary/traditional users would include: • Incidental ingestion of, dermal contact with, and inhalation of dust from surface soil • Incidental ingestion of and dermal contact with surface water and sediment • Consumption of shellfish and fish • Consumption of wild game • Consumption of upland and intertidal plants 4.3.2.2 Intermittent or Seasonal Workers The Salt Chuck Mine site includes lands managed by the U.S. Forest Service. Also, there are currently active mining claims held at and near the Salt Chuck Mine site. For the purposes of the HHRA and given these identified land uses, it is assumed that intermittent or seasonal forestry and/or mine workers would occasionally work at the site and live in nearby Thorne Bay (the closest year-around population) or farther communities. It is also assumed these workers could directly contact upland surface soil, surface water, and sediment. The most plausible exposure routes for intermittent workers would include: • Incidental ingestion of, dermal contact with, and inhalation of dust from upland surface soil • Incidental ingestion of and dermal contact with upland surface water and sediment The exposure parameters used forgenerating RME risk and hazard estimates are listed in Table 6. Many of the exposure assumptions for ingestion, dermal contact, and inhalation are default values provided by EPA guidance documents (listed in Section 4.1). Some of the exposure assumptions (e.g., exposure frequencies and durations for all receptors) will be based on site-specific information or best judgment. 4.3.3 Calculation of Chemical Intake Exposure that is normalized overtime and body weight is termed intake (expressed as milligrams of chemical per kilogram body weight per day [mg/kg-day]). This section describes the equations that will be used to calculate exposures to contaminants in surface soil, sediment, surface water, ambient air, and edible biota. Consistent with EPA guidance, exposure estimates will be calculated for RME conditions. 4.3.3.1 Incidental Ingestion of Soil or Sediment The following equation will be used to estimate the intake associated with the incidental ingestion of contaminants in soil or sediment for the recreational user (soil and sediment), customary/traditional user (soil and sediment), and intermittent worker (soil), exposure scenarios: T , Cs xIR x\0~6kg/mgxEF xED Intake =— 2 2 BWxAT where: Cs Constituent concentration in soil or sediment (mg/kg) IRs Soil or sediment ingestion rate (mg/day) EF Exposure frequency (days/year) ED Exposure duration (years) BW Body weight (kg) AT Averaging time (days) The exposure assumptions to be used for estimating chemical intake from the ingestion of contaminants in soil or sediment are provided in Table 6. 2 Exposure estimates may initially assume 100 percent of food items come from the site, but could be adjusted based on consideration of local community questionnaire results. 4-4 ES011013043021SEA ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY 4.3.3.2 Incidental Dermal Contact with Soil or Sediment Chemical intake from dermal contact with soil or sediment for the recreational user (soil and sediment), customary/traditional user (soil and sediment), and intermittent worker (soil) exposure scenarios will be estimated using the following equation: T , C<. x SAxABS xAF x EF x ED xlCT6kg/mg Intake =— - BWxAT where: Cs = Constituent concentration in soil or sediment (mg/kg) SA = Exposed skin surface area (cm2) ABS = Fraction of constituent absorbed from soil/sediment to skin (unitless) AF = Skin adherence factor (mg/cm2) EF = Exposure frequency (days/year) ED = Exposure duration (years) BW = Body weight (kg) AT = Averaging time (days) The exposure assumptions to be used for estimating exposure from dermal contact with soil or sediment are provided in Table 6. Dermal absorption fractions (ABS) values will be derived from the EPA's Supplemental Guidance for Dermal Risk Assessment (EPA, 2004). 4.3.3.3 Inhalation of Fugitive Dust Originating from Surface Soil In accordance with EPA (2009a), the exposure concentration from inhalation of fugitive dust emissions originating from surface soilforthe recreational user, customary/traditional user, and intermittent worker exposure scenarios will be estimated using the following equation: C. EC„ = — r 1 1 , ETxEFxED PEF VF AT where: ECa = Exposure concentration in ambient air(mg/m3) Cs = Constituent concentration in soil or sediment (mg/kg) ET = Exposure time (unitless fraction of day) EF = Exposure frequency (days/year) ED = Exposure duration (years) PEF = Particulate emission factor(m3/kg) VF = Volatilization factor (m3/kg) AT = Averaging time (days) The particulate emission factor (PEF) to be used is the default value recommended by EPA Regional Screening Levels (RSLs) (EPA, 2012a). The exposure assumptions to be used to estimate exposure from inhalation of dust from surface soil are provided in Table 6. 4.3.3.4 Incidental Ingestion of Surface Water The following equation will be used to estimate the intake associated with the incidental ingestion of constituents in surface waterforthe recreational user, customary/traditional user, and intermittent worker exposure scenarios: C xIRxEFxED Intake =- BWxAT ES011013043021SEA 4-5 ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY where: Cw = Constituent concentration in surface water (mg/L) IRw = Surface water ingestion rate (L/day) EF Exposure frequency (days/year) ED Exposure duration (years) BW Body weight (kg) AT Averaging time (days) The exposure assumptions to be used for estimating chemical intake from the incidental ingestion of constituents in surface water are provided in Table 6. 4.3.3.5 Incidental Dermal Contact with Surface Water Chemical intake from dermal contact with surface water for the recreational user, customary/traditional user, and intermittent worker exposure scenarios will be estimated using the following equation: Make=DA-"xSAxEFxED BW xAT where: DAevent = Calculated in accordance with EPA (2004) (mg/cm2-event) SA = Exposed skin surface area (cm2) EF = Exposure frequency (days/year) ED = Exposure duration (years) BW = Body weight (kg) AT = Averaging time (days) DAevent will be calculated for inorganic chemicals detected in surface water as follows: DA = K xC xt event p sh1 event where: DAevent = Absorbed dose per event (mg/cm2-event) Kp = Dermal permeability coefficient (cm/hour) Csw = Constituent concentration in surface water (mg/cm3) tevent = Event duration (hr/event) The exposure assumptions to be used to estimate exposure from dermal contact with surface water are provided in Table 6. Chemical-specific dermal permeability coefficients (Kp) will be obtained from the Oak Ridge National Laboratory (ORNL) Risk Assessment Information System (ORNL 2011), calculated using EPA's Dermwin™ tool that is part of its Estimation Program Interface (EPI) Suite program. 4.3.3.6 Consumption of Wild Plants The following age-weighted equation will be used to calculate the intake associated with the ingestion of COPCs in native plants for recreational user and customary/traditional user exposure scenarios: C x IFP ,.xFI x EF x 10 6 kglmg Intake = -Z ^^ AT where: !¦:!). x I IIP, I CI) , x I HP IFP' = ¦ BW„ BW„ ES011013043021SEA ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY and where: Cp = Constituent concentration in wild plants (mg/kg) IFPadj Age-adjusted plant ingestion factor[(mg-year)/(kg-day)] IRPa Adult wild plant ingestion rate (mg/day) IRPc Child wild plant ingestion rate (mg/day) BWa Adult body weight (kg) BWC Child body weight (kg) Fl Fraction ingested from contaminated source (unitless) EF Exposure frequency (days/year) EDa Adult exposure duration (years) EDc Child exposure duration (years) AT Averaging time (days) 4.3.3.7 Consumption of Wild Game Calculation of intake from consumption of wild game will be conducted in two steps. First, the COPC concentration in meat tissue will be estimated from measured concentrations in site soils. Second, the COPC intake from daily consumption of these foods will be calculated. The equations for these two steps are as follows: The equation for estimating the chemical concentration in animal tissue is adapted from equations 6-2 and 6-25 of EPA guidance in Methodology for Assessing Health Risks Associated with Multiple Pathways of Exposure to Combustor Emissions (EPA, 1998a) as follows: CT = ((r , X J'p X !•) + (c xP))x BAFl X where: CT = Constituent concentration in wild game tissue (mg/kg) Cp = Constituent concentration in wild plant (mg/kg) Pp = Proportion of animal diet as wild plants (unitless) F = Fraction of game animal diet originating from site3 (unitless) Cs = Constituent concentration in soil (mg/kg) Ps = Proportion of diet as incidentally ingested soil (unitless) BAFl = Diet-to-animal tissue lipid bioaccumulation factor (unitless) Lt = Fraction of game animal tissue as lipid (unitless) Chemical intake from the consumption of wild game harvested from the site, forthe recreational user and customary/traditional user exposure scenarios, will be estimated using the following equation: Ct x IRt x 1CT3 xFI x EF x ED Intake = BWxAT where: CT = Constituent concentration in wild game tissue (mg/kg, wet-weight basis) IRt = Wild game ingestion rate (g/day, wet-weight basis) Fl = Fraction ingested from contaminated source (unitless) EF = Exposure frequency (days/year) ED = Exposure duration (years) BW = Body weight (kg) AT = Averaging time (days) 3 Accounts for area useby harvested wildlife ES011013043021SEA ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY 4.3.3.8 Consumption of Shellfish Chemical intake from the consumption of shellfish harvested from the site, forthe recreational user and customary/traditional user exposure scenarios, will be estimated using the following equation: Intake where Ct x IRt x 10 3 xFI x EF x ED Ct IRt Fl EF ED BW AT Constituent concentration in shellfish tissue (mg/kg, wet-weight basis) Shellfish tissue ingestion rate (g/day, wet-weight basis) Fraction ingested from contaminated source (unitless) Exposure frequency (days/year) Exposure duration (years) Body weight (kg) Averaging time (days) The constituent concentrations in shellfish tissues will come from direct measurements during the 2011, 2012, and 2013 Rl. Based on the types of constituents found at the site, and since most site contamination is associated with intertidaI sediment, it is anticipated that concentrations found in shellfish will provide the most conservative estimates of potential consumption exposure, when compared to potential consumption of locally-harvested fish. The exposure assumptions to be used to estimate exposure from biota consumption are provided in Table 6. There are no default agency-derived ingestion rates for wild food. Wild food intake rates for all receptors (recreational and customary/traditional users) will be developed prior to development of the HHRA. Available data sources on customary/traditional use and consumption rates for the communities of Kasaan, Hollis, and Craig will be considered, including the Alaska Department of Fish and Game (ADFG) Division of Subsistence, Community Subsistence Information System (ADFG, 2013a) and the Final Report on the Alaska Traditional Diet Survey (ANHB, 2004). 4.3.3.9 Calculation of Intake for Mutagenic COPCs Early-in-life susceptibility to carcinogens has been recognized by the scientific community as a public health concern. In its revised cancer assessment guidelines, EPA concluded that existing risk assessment approaches did not adequately address the possibility that exposures to a chemical in early life can result in higher lifetime cancer risks than a comparable duration adult exposure (EPA, 2005). In order to address this potential for increased risk, EPA recommends use of a potency adjustment to account for early-in-life exposures. When no chemical-specific data are available to directly assess cancer susceptibility from early-life exposure, the following default Age Dependent Adjustment Factors (ADAFs) are recommended for use when evaluating a carcinogen known to cause cancer through a mutagenic mode of action: • 10-fold adjustment for exposures during the first two years of life; • Three-fold adjustment for exposures from ages 2 to <16; and • No adjustment for exposures after turning 16 years of age. Of the contaminants evaluated during the 2011 and 2012 Rl, EPA considers that there is sufficient weight of evidence to conclude that the carcinogenic PAHs cause cancer through a mutagenic mode of action. Consideration of early-life stage exposure forthese PAHs would be limited to the recreational and customary/traditional user exposure scenarios. The toxicity assessment component of the HHRA identifies the types of toxic effects a chemical can exert. Chemicals are divided into two broad groups on the basis of their effects on human health: noncarcinogens and carcinogens. This classification has been selected because health risks are calculated quite differently for carcinogenic and noncarcinogenic effects, and separate toxicity values are developed for them. 4.4 Human Health Toxicity Assessment 4-8 ES011013043021SEA ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY Carcinogens are those chemicals suspected of causing cancer following exposure; noncarcinogenic effects cover a wide variety of systemic effects, such as liver toxicity or developmental effects. Some chemicals (such as arsenic) are capable of eliciting both carcinogenic and noncarcinogenic responses; therefore, these carcinogens will be also evaluated for systemic (noncarcinogenic) effects. 4.4.1 Reference Doses for Noncancer Effects The toxicity value describing the dose-response relationship for noncancer effects is the reference dose value (RfD), or in the case of inhalation, the reference concentration, or RfC. For noncarcinogenic effects, the body's protective mechanisms must be overcome before an adverse effect is manifested. If exposure is high enough and these protective mechanisms (or thresholds) are exceeded, adverse health effects can occur. EPA attempts to identify the upper bound of this tolerance range in the development of noncancer toxicity values. EPA uses the apparent toxic threshold value, in conjunction with uncertainty factors based on the strength of the toxicological evidence, to derive an RfD or RfC. EPA defines an RfD (also applies to RfC) as follows (EPA, 1989): "In generalthe RfD is an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. The RfD is generally expressed in units of mg/kg of body weight each day (mg/kg-day)." The HHRA will use available chronic RfDs and RfCsforthe oral and inhalation exposure routes, respectively. Because EPA has not derived toxicity values specific to skin contact, dermal RfDs will be derived in accordance with the EPA Supplemental Guidance for Dermal Risk Assessment (2004). The RfD that reflects the absorbed dose will be calculated by using the following equation: The EPA recommends adjusting oral toxicity values only when evidence suggests that Gl absorption is less than 50 percent. Gl absorption efficiencies will be obtained from the Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation Manual Part E, Supplemental Guidance for Dermal Risk Assessment (EPA, 2004). 4.4.2 Slope Factors for Cancer Effects The dose-response relationship for cancer effects is expressed as a cancer slope factor (SFs) that converts estimated intake directly to excess lifetime cancer risk. SFs are presented in units of risk per level of exposure (or intake). The data used for estimating the dose-response relationship are taken from lifetime animal studies or human occupational or epidemiological studies in which excess cancer risk has been associated with exposure to the chemical. However, because risk at low intake levels cannot be directly measured in animal or human epidemiological studies, a number of mathematical models and procedures have been developed to extrapolate from the high doses used in the studies to the low doses typically associated with environmental exposures. The model choice leads to uncertainty. EPA generally assumes linearity at low doses and uses the linearized multistage procedure when uncertainty exists about the mechanism of action of a carcinogen and when information suggesting nonlinearity is absent. It is assumed, therefore, that if a cancer response occurs at the dose levels used in the studies, there is some probability that a response will occur at all lower exposure levels (that is, a dose-response relationship with no threshold is assumed). Moreover, the dose-response slope chosen is usually the UCLonthe dose-response curve observed in the laboratory studies. As a result, uncertainty and conservatism are built into the EPA risk extrapolation approach. EPA has stated that cancer risks estimated by this method produce estimates that "provide a rough but plausible upper limit of risk." In other words, it is not likely that the true risk would be much more than the estimated risk, but "the true value of the risk is unknown and may be as low as zero" (EPA, 1986a). RfDABS=RJD0xABSGI where: RfDABS RfD0 ABSgi Absorbed reference dose Oral reference dose Gastrointestinal (Gl) absorption efficiency ES011013043021SEA 4-9 ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY Because EPA has not derived toxicity values specific to skin contact, dermal SFs will be derived in accordance with the EPA Supplemental Guidance for Dermal Risk Assessment (EPA, 2004). The SF that reflects the absorbed dose will be calculated by using the following equation: The EPA recommends adjusting oral toxicity values only when evidence suggests that Gl absorption is less than 50 percent. Gl absorption efficiencies will be obtained from the Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation Manual Part E, Supplemental Guidance for Dermal Risk Assessment (EPA, 2004). For the inhalation route, the HHRA will use the inhalation unit risk (IUR) to estimate risk in accordance with Risk Assessment Guidance for Superfund-Volume I: Human Health Evaluation Manual (Part F, Supplemental Guidance for Inhalation Risk Assessment) (EPA, 2009a). EPA defines an IURas"the upper-bound excess lifetime cancer risk estimated to result from continuous exposure to an agent at a concentration of 1 ng/m3 in air" (EPA, 2008). For cancer effects, EPA developed a carcinogen classification system (EPA, 1986a) that used a weight-of-evidence approach to classify the likelihood that a chemical is a human carcinogen. This classification scheme has been superseded in the more recent Guidelines for Carcinogen Risk Assessment (EPA, 2005), where a narrative approach, rather than the alphanumeric categories, is used to characterize carcinogenicity. Five standard weight- of-evidence descriptors are used: Carcinogenic to Humans, Likely to Be Carcinogenic to Humans, Suggestive Evidence of Carcinogenic PotentialInadequate Information to Assess Carcinogenic Potentialand Not Likely to Be Carcinogenic to Humans. 4.4.3 Sources of Toxicity Values In accordance with EPA guidance (EPA, 2003a), the toxicity values (cancer slope factors and reference doses) used in the HHRA will be obtained from the following sources in order of preference: • The Integrated Risk Information System (IRIS) database available through the EPA Environmental Criteria and Assessments Office in Cincinnati, Ohio (EPA, 2012a). IRIS, prepared and maintained by EPA, is an electronic database containing health risk and EPA regulatory information on specific chemicals. • EPA Provisional Peer Reviewed Toxicity Values (PPRTVs), provided by the Office of Research and Development, National Center for Environmental Assessment, Superfund Health Risk Technical Support Center, which develops these values on a chemical-specific basis when requested under the EPA Superfund program. PPRTVs will be obtained from EPA regional screening level (RSL) tables (EPA, 2012b). • Other sources of information, with a preference for sources that (1) provide toxicity information based on similar methods and procedures as those used for IRIS and PPRTV values, and (2) contain values that are peer- reviewed, available to the public, and transparent with respect to the methods and processes used to develop the values. Examples of recommended sources include, but are not limited to, the California Environmental Protection Agency (CAEPA), available at http://www.oehha.ca.gov/tcdb/, and the Agency for Toxic Substances and Disease Registry (ATSDR) Minimal Risk Levels (MRLs), which represent estimates ofthe daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse non-cancer health effects over a specified duration of exposure. The toxicity values to be used in the HHRA are listed in Table 7. The most current version ofthe EPA RSL tables will be used forthe risk assessment. SFa absgi where: SFabs SF0 ABSgi Absorbed slope factor Oral slope factor Gl absorption efficiency 4-10 ES011013043021SEA ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY 4.4.4 Use of Toxicity Equivalency Factors for PAHs If carcinogenic PAHs (cPAHs) are identified as COPCs at the site, they will be assessed using a toxicity equivalency factor (TEF) approach consistent with the EPA's Provisional Guidance for Quantitative Risk Assessment of Poly cyclic Aromatic Hydrocarbons (EPA, 1993a). The TEFs to be used to assess the potency of individual PAHs relative to benzo(a)pyrene are as follows: Carcinogenic PAH Compound: TEF Benzo(a)pyrene: 1 Benzo(a)anthracene: 0.1 Benzo(b)fluoranthene: 0.1 Benzo(k)fluoranthene: 0.01 Chrysene: 0.001 Dibenz(a,h)anthracene: 1 lndeno(l,2,3-cd)pyrene: 0.1 4.5 Human Health Risk Characterization This section summarizes the methods to be used to develop the human health risk estimates for Salt Chuck Mine. In the risk characterization step, quantification of risk is accomplished by combining the results of the exposure assessment (estimated chemical intakes and exposure concentrations) with the results of the dose-response assessment (toxicity values identified in the toxicity assessment) to provide numerical estimates of potential human health effects. The approach differs for potential cancer and noncancer effects, as described in the following sections. Although the HHRA will produce numerical estimates of risk, it should be recognized that these numbers are not predictive of actual health outcomes. Rather, they will provide a frame of reference for risk management decision- making, and interpretation of the risk estimates provided should consider the nature and weight of evidence supporting these estimates, as well as the magnitude of uncertainty surrounding them. 4.5.1 Noncancer Hazard Estimation For noncancer effects, the likelihood that a receptor will develop an adverse effect will be estimated by comparing the predicted level of exposure for a particular chemical with the highest level of exposure that is considered protective (that is, its RfD). The ratio of the intake divided by RfD is termed the hazard quotient (HQ): Intake H(2 = - RfD where: HQ = Noncancer hazard quotient from route of exposure Intake = Chronic daily intake averaged over the exposure duration (mg/kg-day) RfD = Noncancer reference dose (mg/kg-day) For noncancer effects by inhalation exposure, the following equation will be used: EC HQmh = RfC where: HQinh = Noncancer hazard quotient from inhalation EC = Exposure concentration in air (mg/m3) RfC = Noncancer reference concentration (mg/m3) When the HQ for a chemical exceeds 1 (i.e., exposure exceeds the RfD or RfC), there is a concern for potential noncancer health effects. To assess the potential for noncancer effects posed by exposure to multiple chemicals, a ES011013043021SEA 4-11 ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY hazard index (HI) approach will be used in accordance with EPA guidance (1989). This approach assumes that the noncancer hazard associated with exposure to more than one chemical is additive; therefore, synergistic or antagonistic interactions between chemicals are not accounted for. The HI may exceed 1 even if all the individual HQs are less than 1. In this case, the chemicals may be segregated by similar mechanisms of toxicity and toxicological effects. Separate His may then be derived based on mechanism and effect. The HI will be calculated as follows: Intake, Intake 0 Intake HI = L + - + ...- RfDx RfD2 RfDi where: HI = Hazard index Intake, = Daily intake of the ith chemical (mg/kg-day) RfDi = Reference dose of the ith chemical (mg/kg-day) Both intake and RfD (or in the case of inhalation, the exposure concentration and RfC) are expressed in the same units (mg/kg-day ormg/m3) and represent the same exposure period (i.e., chronic exposure). 4.5.2 Cancer Risk Estimation The potential for cancer effects will be evaluated by estimating excess lifetime cancer risk (ELCR). This risk is the incremental increase in the probability of developing cancer during one's lifetime in addition to the background probability of developing cancer (i.e., if no exposure to mine-related chemicals occurs). For example, an ELCR of 2 x 10"6 means that for every 1 million people exposed to the carcinogen throughout their lifetimes, the average incidence of cancer may increase by two cases of cancer. In the United States, the background probability of developing cancer for men is a little less than one in two and forwomen is a little more than one in three (American Cancer Society 2008). As previously noted, cancer slope factors developed by EPA represent upper- bound estimates; therefore, any cancer risks generated in the HHRA should be regarded as an upper bound on the potential cancer risks. The actual cancer risk may be less than that predicted, and may be zero (EPA, 1989). ELCR will be estimated by using the following equation: Risk = Intake x SF where: Risk = Excess lifetime cancer risk (unitless probability) Intake = Chronic daily intake averaged over a lifetime (mg/kg-day) SF = Cancer slope factor (mg/kg-day)"1 Inhalation risk will be calculated by multiplying the exposure concentration by the inhalation unit risk (IUR). The IUR is expressed in different units than the cancer slope factor (above), and a conversion factor is necessary to normalize units between the IUR and exposure concentration values. Inhalation risk is estimated by using the following formula: Riskinh=ECa xIURxCF where: Riskmh = Excess lifetime cancer risk from inhalation (unitless probability) ECa = Exposure concentration in air (mg/m3) IUR = Inhalation unit risk (ng/rn3)"1 CF = Conversion factor (ng/mg) Although synergistic or antagonistic interactions might occur between cancer-causing chemicals and other chemicals, information is generally lacking in the toxicological literature to predict quantitatively the effects of these potential interactions. Therefore, cancer risks are treated as additive within an exposure route in this assessment. This approach is consistent with the EPA guidelines forthe health risk assessment of chemical 4-12 ES011013043021SEA ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY mixtures (EPA, 1986b). For estimating the cancer risks from exposure to multiple carcinogens from a single exposure route, the following equation is used: RiskT = y , Risk, where: RiskT = Total cancer risk from route of exposure Risk, = Cancer risk for the ith chemical N = Number of chemicals The human health risk will be calculated using a two-step process: (1) calculate risk (either ELCR or HQ) from the EPCs for each contaminant, and (2) sum the risk estimates from all contaminants to estimate the total ELCR or HI. The total ELCR and HI estimates will be expressed in one significant figure, in accordance with EPA and ADEC guidance. 4.5.3 Risk Estimation Method for Lead Potential adverse health effects from lead will be evaluated using different methods than those conventionally used for other chemicals. This is because for lead most human health effects data are based on blood lead concentrations rather than on the external dose. The adverse health outcomes, which include neurotoxic and developmental effects, may occur at exposures so low that they may be considered to have no threshold. EPA views it as inappropriate to develop noncarcinogenic "safe" exposure levels (RfDs) for lead. Instead, a biokinetic model is used that relates exposure to measured lead concentrations in the environmental media with an estimated blood-lead level. For the HHRA, potential adverse health effects from lead will be evaluated by comparing the EPC for lead in soil and sediment to the residential and industrial RSLs of 400 mg/kg and 800 mg/kg, respectively (EPA, 2012b). Under federal guidance, the soil RSL for residential land use was derived by EPA using the Integrated Exposure Uptake Biokinetic (IEUBK) Lead Model (EPA, 2010b). The IEUBK model is designed to predict probable blood-lead concentrations for children between 6 months and 7 years of age who have been exposed to lead through various sources (for example, air, water, soil, diet, and in utero contributions from the mother). A predicted blood-lead level of 10 ng/dL in greater than 5 percent of the potentially exposed population is considered by EPA to be a level of concern that triggers intervention to reduce exposure. Blood lead levels above this are therefore considered to pose unacceptable risk. The soil RSL for worker scenarios was derived by EPA based on the Adult Lead Model (ALM) version date June 21, 2009 (EPA, 2003b). The ALM develops a risk-based soil concentration that is protective of fetuses carried by women who may be exposed to lead. Potential risk from lead in surface water will be conservatively evaluated by comparing the EPC in water to the drinking water action level of 0.015 milligrams per liter [mg/L]). 4.5.4 Consideration of Contribution from Ambient Levels of Metals Because some metal concentrations are known to be higher in the region due to natural mineralization, ambient levels of metals could contribute to the total exposure and risk estimates for the mine site releases. Therefore, it is important to determine what portion of the site concentrations detected is due to the site-related releases, compared to the portion representing ambient for Salt Chuck Mine. Ambient refers to the range of concentrations of the chemical in similar nearby reference areas that have not been affected by the mining activities. The HHRA will provide ELCR and hazard estimates both for Salt Chuck Mine exposure areas and for ambient exposure areas, for comparative purposes. In addition, the incremental risks or hazards will be estimated as the difference between the Salt Chuck Mine ELCRs or hazards and those from ambient reference area concentration levels. Ambient reference area samples were collected from locations that have no documented or visually apparent active mining activity or impacts near or at the Salt Chuck Mine area ES011013043021SEA 4-13 ------- 4 HUMAN HEALTH RISK ASSESSM ENT METHODOLOGY 4.5.5 Action Levels for Human Health For the purposes of the HHRA, the potential for unacceptable human health risk will be identified in accordance with EPA guidance (EPA, 1991b), using the following risk thresholds: • In interpreting estimates of excess lifetime cancer risks, EPA under the Superfund program generally considers action to be warranted when the multi-chemical aggregate cancer risk forall exposure routes within a specific exposure scenario exceeds 1 x 10"4. Action generally is not required for risks falling within 1 x 10"6 and 1 x 10~4; however, this is judged on a case-by-case basis. Under state guidance, ADEC considers a cancer risk exceeding 1 x 10"5 as unacceptable risk. • Under EPA and ADEC guidance, unacceptable noncancer hazard exists if the multi-chemical aggregate noncancer hazard forall exposure routes within a specific exposure scenario exceeds a target noncancer HI of 1 for toxicants that have similar mechanisms of action. • If lead concentrations in environmental media result in a predicted blood-lead level of 10 micrograms per deciliter (|a.g/d L) in greater than 5 percent of the potentially exposed population, lead is present at unacceptable levels. 4.6 Uncertainty Analysis Risk assessment as a science is subject to uncertainty, both for risk assessment in general and for an understanding of location-specific conditions. Overall uncertainties associated with the human health evaluation pertain to: • Sampling and analysis • Fate and transport estimation • Exposure estimation • Toxicological data A qualitative uncertainty analysis for Salt Chuck Mine will be conducted to identify specific causes of uncertainties and evaluate their potential impact on risk estimates. This information will be presented in a summary table for each specific risk assessment step, and will identify the specific source and effect of the uncertainty factor on the resulting risk estimates for the site (i.e., whether the factortends to over or underestimate calculated risk). 4-14 ES011013043021SEA ------- 5. Ecological Risk Assessment Methodology This section describes the methodology forthe ERA to be conducted for the Salt Chuck Mine site. The ERA will evaluate the likelihood that adverse ecological effects could occur as a result of exposure to one or more mine- related stressors (EPA, 1992b). The overall objective of the ERA will be to quantitatively and qualitatively evaluate baseline or existing exposure and risks to ecological receptors, and to provide risk managers with information needed to achieve their ecological management goals and help determine remedial decisions, if necessary. The ERA will characterize the ecological communities at and in the vicinity of the Salt Chuck Mine site, identify complete ecological exposure routes, identify particular hazardous substances of ecological concern, and determine whether ecological exposures are estimated to pose unacceptable risks and therefore may need to be addressed during a Feasibility Study. The ERA will address potential ecological effects affecting habitats and ecological receptors using the Salt Chuck Mine site, including vegetation, terrestrial invertebrates, wildlife (birds and mammals), aquatic life (fish, invertebrates, shellfish), identify potential T&E species using the Salt Chuck Mine site, and other sensitive habitats associated with the Salt Chuck Mine site. The ERA will use multiple lines of evidence, to determine whether any releases at the site could pose unacceptable risk to these ecological receptors. 5.1 Ecological Risk Assessment Guidance Several guidance documents will be used to provide direction for developing the ERA. These include, but are not limited to, the following: • Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments, Interim Final (EPA, 1997a) • Final Guidelines for Ecological Risk Assessment (EPA, 1998b) • Ecological Risk Assessment and Risk Management Principles for Superfund Sites (EPA, 1999) • The Role of Screening-Level Risk Assessments and Refining Contaminants of Concern in Baseline Ecological Risk Assessments (EPA, 2001) • Wildlife Exposure Factors Handbook (EPA, 1993b) • Eco Updates, Volume 1, Numbers 1 through 5 (EPA, 1991c, 1991d, 1992c, 1992d, 1992e) • Eco Updates, Volume 2, Numbers 1 through 4 (EPA, 1994a, 1994b, 1994c, 1994d) • Eco Updates, Volume 3, Numbers 1 and 2 (EPA, 1996b, 1996c) • Conceptual Site Model Policy Guidance (ADEC, 2010) • Draft Risk Assessment Procedures Manual (ADEC, 2011) • Technical Background Document for Selection and Application of Default Assessment Endpoints and Indicator Species in Alaskan Ecoregions (ADEC, 1999) 5.2 EPA's Risk Assessment Process The ERA will follow the eight-step approach recommended by EPA (1997a). This process is shown in Figure 8 and is listed as follows: • Step 1. Screening-level problem formulation and ecological effects evaluation • Step 2. Screening-level exposure estimate and risk calculation • Step 3. Baseline risk assessment problem formulation • Step 4. Study design and data quality objective (DQO) process • Step 5. Verification of field sampling plan ES011013043021SEA 5-1 ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY • Step 6. Site investigation and data analysis • Step 7. Risk characterization • Step 8. Risk management The process begins with the screening level ecological risk assessment (SLERA) which will use intentionally conservative assumptions to screen the initial list of detected constituents to identify those constituents requiring further evaluation. The principal components of the SLERA are the screening level problem formulation (Step 1), exposure estimation, effects evaluation, and screening level risk calculation (Step 2). If any chemicals of potential ecological concern (COPECs) are present at concentrations that indicate the need for further evaluation, the process is repeated using more site-specific and, generally, less conservative exposure assumptions and a second risk calculation that includes a less conservative toxicity reference value (Step 3, baseline problem formulation). These refined calculations can lead to a decision to conduct additional studies to further refine exposure estimates and effects relationships (Steps 4 through 6) or, through completion of Step 7, serve as the baseline ERAforthe site. The final step, Step 8, concludes with risk management decisions. Compile Existing Information Step 1: Screening-Level Problem Formulation Step 2: Screening-Level Exposure Estimate and Risk Calculation SMDP SMDP Assessment Endpoints Toxicity Evaluation »¦ Questions/Hypotheses Data Collection Conceptual Model Exposure Pathways Step 3: Problem Formulation Step 4: Study Design and DQO Process Step 5: Verification of Field Sampling Design Step 6: Site Investigation and Data Analysis SMDP SMDP SMDP Step 7: Risk Characterization Step 8: Risk Management SMDP SMDP = Scientific Management Decision Point Adapted from Ecological Risk Assessment Process for Superfund (EPA, 1997) FIGURE 8 EPA's Eight-step Ecological Risk Assessment Process for Superfund Risk Assessment Work Plan, Remedial Investigation, Salt Chuck Mine, Tongass National Forest, Alaska 5-2 ES011013043021SEA ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY EPA recognizes that the eight-step approach is not a linear or sequential process and some steps may not be necessary to reach a decision point. Throughout the ERA process, the risk assessment review team, risk managers, and stakeholders will evaluate available information and discuss and agree upon results and future needs of the ERA. This communication between the ecological risk review team and the risk managers is termed the Scientific Management Decision Point (SMDP). It is an integral part of the ERA process. Possible decision points include: (1) no further action is warranted, (2) further evaluation is warranted, (3) additional data are required, or (4) remedial action is warranted. 5.3 Screening Level Problem Formulation (Step 1) The screening level problem formulation establishes the goals, scope, and focus of the ERA. A description of the environmental setting and a summary of available data are compiled to formulate the CSM. From this information, the exposure pathways, target receptors, and potential effects are determined and serve as the focus for Step 2. Step 1 has been completed as part of this RAWP with the elements described in the CSM (Section 2), including the ecological setting (Section 2.3) and potentially complete ecological exposure pathways and receptors (Section 2.6.4) and those presented in the subsections that follow. 5.3.1 Selection of Representative Endpoint Species To evaluate ecological exposure, representative endpoint species are selected forthe functional feeding guilds identified in the ecological CSM. For example, a belted kingfisher may be considered representative of piscivorous birds visiting the site. Consistent with Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments, Interim Final (EPA, 1997a), these endpoint species should preferably be ones that have ecological relevance, are of societal value, are susceptible to chemical stressors at the site, and allow risk managers to meet policy goals. These factors are used to select representative endpoint species common to the Salt Chuck Mine site or adjacent habitats. As described in Section 2 and depicted in Figures 6 and 7, separate conceptual exposure models were developed for intertidaI and upland areas. The representative species selected for each feeding guild and habitat type at the Salt Chuck Mine site are as follows: • Terrestrial and riparian plants—community level • Intertidal plants—community level • Terrestrial invertebrates—community level • Freshwater aquatic biota (fish, amphibians, water column invertebrates, and benthic infauna)—community level • Marine/estuarine aquatic biota (fish, water column invertebrates, benthic infauna, and epibenthic infauna)— community level • Upland omnivorous birds— Chestnut-backed Chickadee (Poecile rufescens) • Upland/lntertidaI omnivorous mammals—black bear (Ursus americanus) • Upland carnivorous birds —Northern Shrike (Lanius excubitor) • Upland carnivorous mammals—gray wolf (Canis lupus) • Upland/Riparian herbivorous birds—Spruce Grouse (Falcipennis canadensis) • Upland/Riparian herbivorous mammals—Sitka black-tailed deer (Odocoileus hemionus sitkensis) • Riparian insectivorous mammals—dusky shrew (Sorex monticolus) • Piscivorous birds—Belted Kingfisher (Ceryle alcyon) • Piscivorous mammals—mink (Mustela vison) ES011013043021SEA 5-3 ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY • Invertivorous shorebirds - Western Sandpiper (Calidris maun) • Herbivorous waterfowl - Mallard (Anas platyrhynchos) Note: Unlike birds and mammals, methods to differentiate exposure and/or effects among different plant, invertebrate, and fish species are largely unavailable. Therefore, individual species are not selected to represent the plant, invertebrate, and fish populations and communities for evaluation. 5.3.2 Assessment and Measurement Endpoints The conclusion of the screening level problem formulation is the identification of assessment and measurement endpoints. Superfund guidance states that assessment endpoints are any adverse effects on ecological receptors, where receptors are populations and communities, habitats, and sensitive environments (EPA, 1997a). The assessment endpoints for the Salt Chuck Mine site are any adverse effects on receptor populations and communities fornon-T&E species. Adverse effects on these assessment endpoints are predicted from measurement endpoints. The measurement endpoints for this site are the effects of chemical exposure on reproduction, survival, or growth, which can be used to predict effects at all levels of organization (individual, population, and community); these factors are considered in the identification and evaluation of appropriate toxicity information. Assessment endpoints frequently cannot be directly measured because they tend to correspond to complex ecosystem attributes. Because of this, the ERA identifies other related measures that serve as representations or surrogates of each assessment endpoint. These measures are called "measures of effect" and "measures of exposure" (EPA, 1998b). The strength of the relationships between these measures and their corresponding assessment endpoints is critical to the identification of ecological adversity. Forthis ERA, these measures will be defined as follows: • Measures of exposure are quantitative or qualitative indicators of a constituent's occurrence and movement in the environment in a way that results in contact with the assessment endpoint. For example, chemical concentrations detected in surface soil serve as a measure of exposure to terrestrial wildlife that could use habitats at the Salt Chuck Mine area. • Measures of effect are measurable adverse changes in an attribute of an assessment endpoint (or its surrogate) in response to a chemical to which it is exposed. For example, literature-derived critical toxicity values from available laboratory studies on birds are used to indicate when fish-eating birds (as represented by the belted kingfisher) may be adversely affected. Based on the information gathered during previous investigations and forthis Rl, the assessment endpoints identified forthe Salt Chuck Mine and the corresponding measures of exposure and effect are summarized in Table 8. 5.4 Screening Level Exposure Estimate and Risk Calculation The screening level risk calculation will be the final step in the SLERA. In this step, the maximum exposure concentrations for each medium will be compared with corresponding, and intentionally conservative ecological screening values (ESVs) to derive screening risk estimates. For example, site-wide maximum media-specific concentrations for all detected constituents will be compared to risk-based screening values without consideration of fraction of time a receptor forages at the Salt Chuck Mine site. If ESVs are unavailable, then the constituents will be carried forward for further evaluation. The ecological screening levels that will be used are described in the following text. 5.4.1 Soil Screening Values The primary source of soil ESVs that will be used are EPA's ecological soil screening levels (Eco SSLs) (EPA, various dates 2003-2008). Soil ESVs for wildlife represent the lowest of the bird and mammal Eco SSL for each detected constituent. The preferential soil ESVs for terrestrial plants is EPA's Eco SSLs. If no Eco SSLs are available, 5-4 ES011013043021SEA ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY toxicological benchmarks for terrestrial plants from other literature sources will be used. The preferential sources of soil ESVs for terrestrial invertebrates are alsoEPA's Eco SSLs. 5.4.2 Surface Water Screening Values The chronic ESVs that will be used are generally protective for most aquatic receptors that reside in the water column including aquatic plants, water-column invertebrates, amphibians, and fish. Groundwater is not directly accessible to ecological receptors at the Salt Chuck Mine. However, under the assumption that mine-related constituents in groundwater may discharge to surface water where aquatic organisms are present (for example, Salt Chuck Bay), detected constituent concentrations in shallow groundwater will also be screened against ESVs. Chronic freshwater aquatic ESVs will be selected using the following hierarchy of sources: • EPA National Recommended Water Quality Criteria (NRWQC) (EPA, 2009b) • Michigan Department of Environmental Quality Rule 57 value database Freshwater Chronic Values (FCVs) (2009) • National Oceanic and Atmospheric Administration Screening Quick Reference Tables (that is, SQuiRTs) (Buchman, 2008) Chronic marine aquatic ESVs will be selected using the following hierarchy of sources: • EPA NRWQC (EPA, 2009b) • National Oceanic and Atmospheric Administration SQuiRTs (Buchman, 2008) 5.4.3 Sediment Screening Values The sediment ESVs that will be used are considered generally protective for most benthic receptors that reside in sediment including benthic microorganisms, benthic invertebrates, and benthic fish. The primary sources that will be used forsediment ESVs are the EPA's Freshwater Sediment Screening Benchmarks available at http://www.epa.gov/reg3hwmd/risk/eco/btag/sbv/fwsed/screenbench.htm and Marine Sediment Screening Benchmarks available at http://www.epa.gov/reg3hwmd/risk/eco/btag/sbv/marsed/screenbench.htm. Additional literature sources of sediment ESVs may include the lowest of the sediment benchmarks reported in the U.S. National Oceanic and Atmospheric Administration Screening Quick Reference Tables (SQuiRTs) from (Buchman, 2008). Wildlife and plants using riparian and intertidaI areas are also potentially exposed to chemicals in sediment. Therefore, chemical concentrations in sediment will also be compared with the ESVs used for soil (for example, EPA's Eco SSLs). 5.4.4 Screening Risk Calculation In this step, the maximum exposure concentrations detected at Salt Chuck Mine area (in each medium) will be compared with the corresponding ESV to derive screening level risk estimates. Detected constituents will be evaluated using the HQ method. HQs will be calculated by dividing the appropriate EPC (for the SLERA; that is, maximum detected concentrations) by corresponding medium-specific ESVs. Constituents with HQs greater than or equal to 1 will be identified as COPECsand carried forward for additional evaluation. Detected constituents for which ESVs are not available will also be carried forward. 5.4.5 Recommendation for SMDP 1 Following Step 2, the first SMDP will occur. This SMDP is intended to communicate the findings of the SLERA and to determine which COPECs, endpoint species, and exposure pathways should be carried forward to Step 3. 5.5 Baseline Ecological Risk Assessment Problem Formulation (Step 3) Upon completion of the SLERA, a list of COPECs will be derived that will serve to focus the baseline ecological risk assessment (BERA) problem formulation. The BERA begins with a refinement of the COPECs, in which the ES011013043021SEA 5-5 ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY conservative assumptions used in the SLERA are refined and risk estimates are calculated with exposure models that allow use of more site-specific assumptions. At the conclusion of Step 3, SMDP 2 will be completed. 5.5.1 Refinements to Risk Estimates Potential effects to plant, invertebrate, and wildlife communities will be assessed using an approach that considers multiple lines of evidence collectively, in accordance with EPA guidance in Guidelines for Ecological Risk Assessment (EPA, 1998b). The various lines of evidence may include the following: 5.5.1.1 Lines of Evidence for Plants 1. Soil EPCswill be calculated using EPA's statistical program ProUCL(EPA, 2011b) following the procedures described in Section 4.3.1 of this RAWP. These EPCswill be compared with ESVs for plants. 2. Relative contribution of background levels will be considered. 3. Many plant benchmarks are based on few studies and limited species. Therefore, the confidence level for plant ESVs will be qualitatively discussed. 5.5.1.2 Lines of Evidence for Terrestrial Invertebrates 1. Soil EPCswill be calculated using EPA's statistical program ProLICL. These EPCs will be compared with ESVs for terrestrial invertebrates. 2. Relative contribution of background levels will be considered. 3. Many invertebrate benchmarks are based on few studies and limited species. Therefore, the confidence level for invertebrate ESVs will be qualitatively discussed. 5.5.1.3 Lines of Evidence for Aquatic Organisms 1. Site-specific hardness data will be used to calculate hardness-derived freshwater thresholds. 2. Data collected nearest to exposure points (for example, surface water collected within streams) will be the focus of the BERA. 3. Relative contribution of background levels will be considered. 5.5.1.4 Lines of Evidence for Sediment Infauna 1. Sediment concentrations will be compared with freshwater sediment probable effects concentrations (MacDonald etal., 2000), marine sediment effects range - median (ER-M) levels (Long and Morgan, 1990), or other comparable levels above which adverse effects are likely to occur. 2. Site-specific sediment bioassay results will be considered. During the 2011-2012 Rl, sediment toxicity was measured using a 20-day test with polychaetes (Neanthes arenaceodentata) and a bivalve embryo-larval development test using a mussel (Mytilus galloprovincialis). 3. Site-specific shellfish tissue concentrations will be compared with tissue residue effects in literature. 4. The relative contribution of background will be considered. 5.5.1.5 Lines of Evidence for Wildlife 1. Soil, sediment, and biota EPCs will be calculated using EPA's statistical program ProLICL. These EPCswill be used in refined exposure estimates. 2. Site-specific food chain models will be used to evaluate the exposures and risk to endpoint species representative of those using the habitats at Salt Chuck Mine. Among other things, these models will incorporate site-specific tissue data forfood items, site-specific area use factors for each representative endpoint species. 3. Chronic-lowest-observed-adverse-effect levels (LOAELs) will be included to evaluate the range of risk associated with a COPEC in each feeding guild. 4. The relative contribution of background will be considered. 5-6 ES011013043021SEA ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY Further lines of evidence may be applied during the concentration-based refinement, which will provide additional information for risk management decision-making, including but not limited to evaluations based on a range of available ESVs, magnitudes of exceedance, spatial variability of COPEC concentrations, or other site-related considerations. 5.5.2 Wildlife Exposure Modeling The following subsections describe the methods and equations that will be used to compute potential exposure to wildlife in the BERA. 5.5.2.1 Wildlife Dosage-Based Exposure Model The general exposure model to be used for birds and mammals is based on exposure to contaminants through multiple pathways including soil/sediment, surface water, and food items. To address these multiple pathways, modeling will be required. Exposure estimates for each representative species will be generated according to the following: • Media of concern • EPCs for abiotic media • Receptor-specific exposure factors (or life-history parameters) • Bioaccumulation potential in food items • Area use factors The end product of the BERA exposure estimate is a dosage (milligrams per kilogram receptor body weight per day) rather than a medium concentration (as would be used for the SLERA). This is a function of both the multiple pathway approach and the typical methods used in toxicity testing for birds and mammals. The following generalized exposure model will be used: xP,xFffl)+ XFIr)+ (Water, xWIR)xAUFxMF where: Ej = Total exposure (mg/kgbw/day) Sj = Constituent concentration in soil/sediment (mg/kg) Ps = Soil/sediment ingestion rate as a proportion of diet FIR = Total food ingestion rate forthe representative species (kgdiet/kgbw-day) Bjj = Constituent concentration (j) in biota type (i) (mg/kg) Pi = Proportion of biota type (i) in diet Waterj = Constituent concentration in water (mg/L) WIR = Total water ingestion rate forthe representative species (L/kgbW-day) AUF = Area use factor (fraction of foraging range) MF = Migration factor (fraction of year) 5.5.2.2 Exposure Point Concentrations EPCs will be developed for each exposure area. Exposure areas will be generally defined as Upland Forest, Riparian/Streams, and IntertidaI. EPCs used in the BERA will be calculated using the EPA's ProLICL statistical program (EPA, 2011b) following the procedures described in Section 4.3.1 of this RAWP. The exposure areas over which investigation data will be aggregated for computation ofUCLswill be determined once the 2013 Rl investigation activities are complete. Due to the geographic scale of the Rl, the spatial representativeness, chemical concentration trends, and numbers of samples will all be considered to decide exposure areas for the risk assessment. Forthe intertida I area, the mud flats adjacent to the former mill site will likely represent a single exposure area where wildlife could be exposed to sediment, water, or biota. Other areas and media with much lower concentrations of mine-related constituents may be addressed using screening approaches, rather than by computing a really-averaged results for exposure areas. ES011013043021SEA 5-7 ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY 5.5.2.3 Exposure Factors Species-specific life history factors are needed to estimate exposure to COPECs for each representative wildlife receptor. These include body weight, food ingestion rates, water ingestion rates, incidental soil or sediment ingestion rates, and diet composition. Species-specific exposure assumptions for estimating wildlife contaminant intake from mine-related COPECs are provided in Table 9. Brief species life history accounts that discuss preferential habitats and food items, foraging area and migration patterns, and breeding habits for each receptor will also be presented in the BERA. The BERAwill conservatively assume that COPECs are 100 percent bioavailable to the receptor. Allometric equations will be used to compute food ingestion and water ingestion rates normalized to the wildlife receptor's body weight, with units of kilograms of dry food per kilogram body weight per day or liters of water per kilogram body weight per day, respectively (Nagy, 2001). 5.5.2.4 Bioaccumulation into Food Items Bioaccumulation can be defined as the uptake and accumulation of chemicals by organisms from the nonliving (abiotic) environment or through the diet. The ERA will evaluate the risk to endpoint species that consume four primary classes of food items (vegetation, fish, invertebrates, and small birds/mammals). Mine-specific COPEC concentrations in food items, measured during the Rl, will be used when available. During the Rl, upland and intertidaI plant tissue and shellfish tissue data have been collected to support the exposure assessments in the BERA. For food items where tissue data have not been directly measured (for example, small mammals), concentrations of a COPEC in those food chain items will be estimated. For these tissues, the partitioning of COPECs from soil, sediment or water to food items will be estimated from literature-reported values or uptake regression models. If site-specific, literature values, or reliable regression models are not available for a given chemical, a default bioaccumulation value of 1 will be used. Medium-specific bioaccumulation factors (BAFs) and bioconcentration factors (BCFs) to be used are described as follows: • Plants. As part of the Rl, dry-weight tissue concentrations for COPECs measured in aboveground vegetative portions of upland and intertida I plants collected at Salt Chuck Mine will be used. These will serve as the primary measures of plant uptake used in the exposure models. • Terrestrial Invertebrates. Dry weight tissue concentrations in soil invertebrates (earthworms) will be estimated by multiplying the soil concentration for each chemical by chemical-specific BAFs (single value or regression equation) obtained from the literature. BAFs based on depurated analyses (soil is purged from the gut of the earthworm before analysis) are given preference over non-depurated analyses when selecting BAF values, because direct ingestion of soil is accounted forseparately in the food-web model. • Small Mammals. Whole-body tissue concentrations in small mammals (shrews, voles, and/or mice) will be estimated using soil-to-small-mammal BAFs. Tissue concentrations will be calculated by multiplying the surface soil concentration for each chemical by a chemical-specific, soil-to-small-mammal BAF (single value or regression equation) obtained from the literature. The BAF values used are based on the ratio between dry- weight soil and whole-body dry-weight tissue. • Benthic Invertebrates. Tissue concentrations in benthic invertebrates will be estimated by multiplying the sediment concentration for each chemical by chemical-specific, sediment-to-invertebrate BAFs obtained from the literature. The BAF values used are based on the ratio between dry-weight sediment and dry-weight invertebrate tissue. In some cases, shellfish tissue data from the Rl may be directly used in lieu of modeling into benthic invertebrate tissue, for purposes of estimating exposure to higher consumers of the invertebrates. • Fish/Shellfish. As part of the Rl, dry-weight tissue concentrations for COPECs measured in whole clams, crabs, and shrimp (excludes shells) collected in Salt Chuck Bay will be used. These will serve as the primary measures offish and shellfish uptake used in the exposure models. A secondary approach could also be used where tissue concentrations in whole-body fish are estimated by multiplying the surface water concentration for each COPEC by BCFs obtained from the literature (primarily from values used for derivation of EPA's National Ambient Water Quality Criteria [NAWQC][EPA, 2002c]). These BCF values are based on the ratio between surface water and wet-weight fish tissue and would require a conversion to a dry-weight basis by dividing the wet-weight BCF by the estimated solids content for fish (25 percent [0.25]) (EPA, 1993b). 5-8 ES011013043021SEA ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY 5.5.2.5 Area Use Factors Many wildlife species are highly mobile, covering relatively large areas in search of food, water, and shelter. As such, the exposure that individual receptors experience depends on the amount of time they spend at a contaminated site. The area use factor(AUF) is a ratio of the size of a site (or exposure area) relative to an animal's foraging range using the following equation. This value is incorporated in the exposure model to give a more realistic estimation of overall exposure. y r,,, Exposure Area AUF =—- FRX where: AUF = Area use factor Exposure Area = Contaminated area or habitat type (acres) FRX = Foraging range for target species x (acres) AUFs will be derived for each exposure area defined, based on its size. If the receptor's foraging range is less than the size of the exposure area, an AUF of 1 will be assumed. 5.5.2.6 Consideration of Endpoint Species Migration The migration factor (MF) is a species-specific temporal adjustment that accounts for migratory habits. It is the fraction of the year that the species is expected to be in the general area of the Salt Chuck Mine. Based on the life history information to be gathered for each endpoint species, migration factors may be applied forthe endpoint species which are not expected to be present year-round. 5.5.3 Wildlife Ecological Effects Assessment The ecological effects assessment will identify the toxicity associated with the chemical stressors at Salt Chuck Mine. It will determine the type and level of effect that could result to the receptor if exposure is excessive. Stressor-response (that is, effects) data that can be used to evaluate ecological risks resulting from chemical exposures originate from three general sources: literature-derived single-chemical toxicity data, site-specific ambient media toxicity tests, and site-specific field surveys (Suter et al., 2000). In most cases, single-chemical toxicity data found in the literature will be used as the basis forthe ESVs and toxicity reference values (TRVs) for the BERA. For evaluation of sediment-dwelling invertebrates, laboratory toxicity test data will be used to directly measure adverse effects. 5.5.3.1 Mammalian and Avian Effects A literature review of the toxicological properties forCOPECs will be conducted to identify the highest exposure level considered to be without adverse ecological impact. This exposure level will be referred to as the TRV. The primary toxicological endpoint used forthe development of the TRV is the chronic-no-observed-adverse-effect level (NOAEL) (in units of mg/kg body weight-day). Chronic-LOAELs are also used to develop secondary TRVs in order to further evaluate the range of risk associated with a COPEC in each feeding guild. TRVs will be derived by interpreting existing toxicology studies and adjusting those data, if necessary, to obtain values that are expected to protect the selected endpoint species. Literature references citing use of laboratory animals that have similar sensitivity, life history, or habitat requirements will be used as surrogates forthe wildlife ecological receptor species. Toxicity data then will be adjusted forthe uncertainty associated with differences between the laboratory tests and the receptor in the environment. Derivation of wildlife TRVs for the endpoint species will involve the following three-step process: 1. Conducting a literature search to compile data on toxicity of the COPECsto surrogate (laboratory test) species. 2. Reviewing these toxicity data to select the most appropriate values for each COPEC. 3. Applying uncertainty factors from the toxicology literature to derive a chronic, NOAEL, or LOAEL, from other endpoints (for example, subchronic studies) if necessary. ES011013043021SEA 5-9 ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY The primary sources of wildlife TRVs for the BERAwill be the EPA's Eco SSLs (EPA, various dates 2003-2008). Additional sources for ecological toxicity information may include but are not limited to the following: Los Alamos National Laboratory Toxicity Database (2012) U.S. Army Center for Health Promotion and Preventive Medicine Wildlife Toxicity Database (2009) Oak Ridge National Laboratory Wildlife TRVs (Sample et al., 1996) Navy Biological Technical Assistance Group TRVs (Engineering Field Activity West, 1998) Agency for Toxic Substances and Disease Registry Toxicological Profiles (2012) Integrated Risk Information System (IRIS) (EPA, 2013) Other peer-reviewed scientific sources When necessary, uncertainty factors will be applied to the literature-derived toxic level to account for any differences in the reported effect level or exposure duration, in accordance with the EPA Region 10 guidance (EPA, 1997b) and with ADEC's Risk Assessment Procedures Manual (ADEC, 2011). 5.5.4 Risk Characterization Methodology Risk characterization is a way of quantitatively or qualitatively characterizing the potential risks for each COPEC and receptor identified in the COPEC screening process. The primary means of characterizing ecological risk for wildlife is to determine the ratio of the estimated chemical exposure level or dose for the wildlife receptor with the COPEC-specific TRV. Hazard quotients can be calculated to quantitatively characterize these risks. The following equation will be used: E, HQ = 1 TRV where: HQ = Ecological hazard quotient (unitless) Ej = Estimated COPEC exposure (mg/kgbW-day) TRV = Toxicity reference value (mg/kgbw-day) The primary means for quantifying ecological risk for plants, aquatic organisms, terrestrial invertebrates, and sediment infauna is to determine the ratio of the estimated COPEC exposure levels for the endpoint species of concern with the COPEC-specific ecological benchmark criterion. FPC HQ = ESV where: HQ = Ecological hazard quotient (unitless) EPC = Exposure point concentration (mg/kg or mg/L) ESV = Ecological screening value criterion (mg/kg or mg/L) The HQ estimates will be expressed in one significant figure, in accordance with EPA and ADEC guidance. A HQ that exceeds 1 indicates that there is a potential foradverse ecological effects associated with exposure to that COPEC and further evaluation of remedial actions may be warranted. A HQ value less than or equal to 1 is considered protective of each receptor's feeding guild that it represents because it is developed using conservative exposure assumptions. HQs will be provided using both NOAEL-based and LOAEL-based TRVs. 5.5.5 Uncertainties Uncertainties are inherent in all ecological risk assessments because ofthe limitations of the available data and the need to make certain assumptions and extrapolations based on incomplete information. In addition, the use of various models (for example, uptake and food web exposures) carries with it some associated uncertainty as to how well the model reflects actual conditions. However, because conservative assumptions are generally used throughout the exposure and effects assessments, these uncertainties are more likely to result in an 5-10 ES011013043021SEA ------- 5 ECOLOGICAL RISK ASSESSM ENT METHODOLOGY overestimation rather than an underestimation of the likelihood and magnitude of risks to ecological receptor. The uncertainties and limitations associated with the proposed methodology and available data for the ERA will be discussed in the risk assessment. 5.5.6 Recommendation for SMDP 2 Following Step 3, SMDP 2 will occur and recommendations on the path forward will be described. If the SMDP 2 does not recommend that data are insufficient and no additional sampling, is warranted, then the eight step ERA process ends here and the results of the ERA are carried into the FS. The risk assessment would provide information necessary for identifying remedial action goals and any remedial action alternatives would be presented in the FS. ES011013043021SEA 5-11 ------- ------- 6. Risk Assessment Report The results of the baseline HHRA and ERAforthe Salt Chuck Mine site will be provided in a risk assessment report in a format consistent with EPA guidelines. This report will be submitted to in accordance with an agreed upon schedule. The results of the risk assessment will be presented in a clear and consistent fashion in the risk assessment report. The risk assessment conclusions will be designed to provide meaningful data to risk managers to be applied during the decision-making process. Once the exposure and risk estimates are complete, the collective weight of evidence will be evaluated, in consultation with the EPA and other stakeholders, to determine the likelihood that unacceptable risk exists. A concise set of conclusions will be provided using a weight-of-evidence approach and with consideration of the uncertainties in the analysis. By evaluating multiple lines of evidence collectively, more confidence in a conclusion of unacceptable risk can be obtained. For the ERA, some lines of evidence (such as bioassay results) will inherently carry more "weight" than others (such as ESV exceedance levels). ES011013043021SEA 6-1 ------- ------- 7. References ADEC (Alaska Department of Environmental Conservation). 1999. Technical Background Document for Selection and Application of Default Assessment Endpoints and Indicator Species in Alaskan Ecoregions. ADEC, Division of Spill Prevention and Response, Contaminated Sites Program, Anchorage, Alaska. ADEC (Alaska Department of Environmental Conservation). 2010. Conceptual Site Model Policy Guidance. ADEC, Division of Spill Prevention and Response, Contaminated Sites Program, Anchorage, Alaska. 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Final Report on the Alaska Traditional Diet Survey.: Alaska Native Epidemiology Center, Anchorage, AK. March 2004. Beyer, W.N., E.E. Connor, and S. Gerould. 1994. Estimates of Soil Ingestion by Wildlife. Allen Press, Lawrence, KS. BLM. 1998. Final Report, Removal Preliminary Assessment, Salt Chuck Mine, Ketchikan Ranger District, Tongass National Forest, Region 10-Alaska. Prepared by U.S. Bureau of Land Management, Juneau Field Office, Interagency Agreement No. 961A-10-012. April 1998. Buchman, M.F., 2008. NOAA Screening Quick Reference Tables. NOAA OR&R Report 08-1, National Oceanic and Atmospheric Administration, Office of Response and Restoration Division, Seattle, Washington, 34 pages. CH2M HILL. 2012a. Draft Quality Assurance Project Plan Salt Chuck Mine Remedial Investigation, Tongass National Forest, Alaska. Prepared for U.S. Environmental Protection Agency Region 10. June. CH2M HILL. 2012b. Salt Chuck Mine - Preliminary Findings for Pre-Remedial Investigation 2011 Field Sampling Activities Technical Memorandum. Prepared for U.S. Environmental Protection Agency. May 7. CH2M HILL. 2013. Salt Chuck Mine - Preliminary Findings for Remedial Investigation 2012 Field Sampling Activities. Prepared for U.S. Environmental Protection Agency Region 10. January. Cornell. 2013. http://www.birds.cornell.edu/Page.aspx?pid=1478. Cornell University. Engineering Field Activity West (EFAW). 1998. Development of Toxicity Reference Values as Part of a Regional Approach for Conducting Ecological Risk Assessments at Naval Facilities in California. Prepared by PRC Environmental Management, Inc. EPA. 1986a. Guidelines for Carcinogen Risk Assessment. U.S. Environmental Protection Agency. Federal Register Vol. 51 33992-34013. September 24, 1986. EPA. 1986b. Guidelines for the Health Risk Assessment of Chemical Mixtures. U.S. Environmental Protection Agency. Federal Register Vol. 51 34014-34041. 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Vol. 1, No. 3, Publication 9345.0-051. March. EPA. 1993a. Provisional Guidance for Quantitative Risk Assessment of Poly cyclic Aromatic Hydrocarbons. U.S. Environmental Protection Agency. Office of Research and Development, Washington, D.C., EPA/600/R- 93/089. EPA. 1993b. Wildlife Exposure Factors Handbook. EPA/600/R-93/187a. December. And sources cited within. EPA. 1993b. Wildlife Exposure Factors Handbook. U.S. Environmental Protection Agency. Office of Health and Environmental Assessment, Washington, D.C. EPA/600/R-93/187. EPA. 1994a. Catalog of Standard Toxicity Tests for Ecological Risk Assessment. U.S. Environmental Protection Agency. Office of Solid Waste and Emergency Response, Eco Update. Vol. 2, No. 2, Publication 9345.0-051, EPA 540-F-94-013. September. EPA. 1994b. Field Studies for Ecological Risk Assessment. U.S. Environmental Protection Agency. Office of Solid Waste and Emergency Response, Eco Update. Vol. 2, No. 3, Publication 9345.0-051, EPA 540-F-94-014. 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ES011013043021SEA 7-5 ------- ------- Tables ------- ------- Table 1 2009-2011 Climate Summary for Craig, Alaska Remedial Investigation, Salt Chuck Mine -Tongass National Forest, Alaska Risk Assessment Work Plan Mean Temperature Maximum Minimum Total Precipitation Month (°F) Temperature (°F) Temperature (°F) (inches) Total Snowfall (inches) 2009 Jan 35.9 60 12 11.05 11.1X Feb 34.5 52 18 6.24 1.6X Mar 35.6 48 18 6.03 12 Apr 42 70 28 5.28 0.0 May 49.2 74 36 3.46 0.0 Jun 54.7 81 41 3.96 0.0 Jul 59.2 75 46 1.22 0.0 Aug 58.4 75 47 5.98 0.0 Sep 54 70 36 13.76 0.0 Oct 47.3X 61 31 10.98 0.0 Nov 40.8 54 29 12.99 0.8 Dec 34.5 49 19 3.06 0.7 Annual 45.5 81 12 84.01 26.2* 2010 Jan 41.2 53 19 7.51 0.8 Feb 41.3 57 28 3.69 0.0 Mar 39.6 53 29 16.27 1.1X Apr 42.3 58 29 6.63 3.8 May 50 69 33 2.98 0.0 Jun 52.7 65 42 5.3 0.0 Jul 56.1 75 47 3.68 0.0 Aug 57.9 77 49 3.92 0.0 Sep 55.2 75 39 9.3 0.0 Oct 47.0X 65 31 16.14 0.0 Nov 40.3 58 23 13.52 1.0 Dec 37.6 52 20 5 2.3X Annual 46.8 77 19 93.94 9.0* 2011 Jan 36.6 48 15 8.35 3.5 Feb 34.4 48 13 6.49 4.1 Mar 38 58 10 5 0.6 Apr 41.6 58 31 6.71 0.3 May 48.2 67 36 4.99 0.0 Jun 53.9 72 44 2.11 0.0 Jul 54.8 70 45 4.84 0.0 Aug NA 68 45 12.35 0.0 Sep 53.4 68 38 18.16 0.0 Oct 46.9 59 37 14.43 0.0 Nov 37.9 48 26 12.37 11.4X Dec 38.4 48 26 9.02 5.2 Annual 40.3 72 10 104.82 25.1* Notes: Source: National Oceanic and Atmospheric Administration National Climate Data Center (NOAA, 2012) Station: COOP:502227, CRAIG, AK. Elevation 43 feet above sea level. Lat. 55.477°, Lon. -133.141° X = Monthly means or totals based on incomplete time series. 1 to 9 days are missing. Annual means or totals include one or more months which had 1 to 9 days that were missing. * = Annual value missing; summary value computed from available month values. NA = not available ------- ------- Table 2 Marine Intertidal Invertebrates Potentially Occurring at Prince of Wales Island Remedial Investigation, Salt Chuck Mine -Tongass National Forest, Alaska Risk Assessment Work Plan Common Name Scientific Name Feeding Habits Hab tats Lugworm Abarenicola pacifica Omnivorous Mar ne/ intertidal/subtidal Black chiton Katherina tunicata Herbivorous Mar ne/ intertidal/subtidal Gumboot chiton Cryptochiton stelleri Herbivorous Mar ne/ intertidal/subtidal Lined chitons Tonicella lineata Herbivorous Mar ne/ intertidal T. insignus Herbivorous Mar ne/ intertidal Moss chiton Mopalia spp. Herbivorous Mar ne/ intertidal Limpets Acmaea mitra Herbivorous Mar ne/ intertidal Notoacmea scutum Herbivorous Mar ne/ intertidal Notoacmea persona Herbivorous Mar ne/ intertidal Snails Littorina scutulata Herbivorous Mar ne/ intertidal Littorina sitkana Herbivorous Mar ne/ intertidal Lacuna carinata Herbivorous Mar ne/ intertidal Natica clausa Carnivorous Mar ne/ intertidal/subtidal Fusitrition oregonensis Carnivorous Mar ne/ intertidal/subtidal Neptunia lyrata Carnivorous Mar ne/ intertidal/subtidal Blue mussel Mytilus trossulus Filter feeder Mar ne/ intertidal Horse mussel Modiolus modiolus Filter feeder Mar ne/subtidal Littleneck clam Protothacea staminea Filter feeder Mar ne/ intertidal/subtidal Butter clam Saxidomus giganteus Filter feeder Mar ne/ intertidal/subtidal Softshell clam My a a re n aria Filter feeder Mar ne/ intertidal/subtidal Acorn barnacle Balanus glandula Filter feeder Mar ne/ intertidal Thatched barnacle Semibalanus cariosus Filter feeder Mar ne/ intertidal Dungeness crab Cancer magister Carnivorous Mar ne/ intertidal/ subtidal Helmet crab Telmessus cheiragonus Carnivorous Mar ne/ intertidal/ subtidal Rock crab Cancer productus Carnivorous Mar ne/ intertidal/ subtidal Tanner crab Chionoecetes bairdi Carnivorous Mar ne/ subtidal Ochra sea star Piaster ochraceus Carnivorous Mar ne/ intertidal/subtidal Sun star Pycnopodia helianthoides Carnivorous Mar ne/ intertidal/subtidal Mottled star Evasterias troschelii Carnivorous Mar ne/ intertidal/subtidal Green sea urchin Stongylocentrotus droebachiensis Herbivorous Mar ne/ intertidal/subtidal Red sea urchin Strongylocentrotus franciscanus Herbivorous Mar ne/ subtidal ------- ------- Table 3 Fish and Amphibian Species Potentially Occurring at Prince of Wales Island Remedial Investigation, Salt Chuck Mine -Tongass National Forest, Alaska Risk Assessment Work Plan Common name Scientific name Group Feeding Habits Habitat Arrowtooth flounder Atheresthes stomias Marine Carnivorous Offshore rocky/inshore sand-gravel Chinook salmon Onchorynchus tshawytscha Anadromous Carnivorous Nearshore marine/freshwater streams Chum salmon Onchorhynchus keta Anadromous Carnivorous Nearshore marine/freshwater streams Coho salmon Onchohynchus kisutch Anadromous Carnivorous Nearshore marine/freshwater streams Cutthroat trout Oncorhynchus clarki Anadromous Carnivorous Inshore marine/freshwater streams Dolly Varden Salvalinus malma Anadromous Carnivorous Inshore marine/freshwater lakes and streams Pacific cod Gadus macrocephalus Marine Carnivorous Offshore rocky/inshore sand-gravel Pacific halibut Hippoglossus stenolepis Marine Carnivorous Offshore rocky/inshore sand-gravel Pacific herring Clupea harengus Marine Carnivorous Offshore/inshore marine Pink salmon Oncorhynchus gorbuscha Anadromous Carnivorous Nearshore marine/freshwater streams Red Irish Lord Hemilepidotus hemilepidotus Marine Carnivorous Offshore rocky/inshore sand-gravel Rock Sole Lepidosetta bilineata Marine Carnivorous Offshore rocky/inshore sand-gravel Sablefish (black cod) Anaplopoma fimbria Marine Carnivorous Offshore rocky/inshore sand-gravel Slimy Sculpin Cottus cognatus Marine Carnivorous Intertidal/inshore marine Sockeye salmon Oncorhynchus nerka Anadromous Carnivorous Inshore marine/freshwater lakes and streams Starry flounder Platicthys stellatus Marine Carnivorous Inshore marine Steelhead trout Oncorhynchus mykiss Anadromous Carnivorous Inshore marine/freshwater streams Walleye pollock Theragra chalcogramma Marine Carnivorous Inshore sand-gravel Yellowfin sole Limanda aspera Marine Carnivorous Offshore rocky/inshore sand-gravel Roughskin newt Taricha granulosa Amphibian Carnivorous Streams/grassland/forest/muskeg Western toad Bufo boreas Amphibian Carnivorous Streams/grassland/forest/muskeg Wood frog Rana sylvatica Amphibian Carnivorous Streams/grassland/forest/muskeg ------- ------- Table 4 Bird Species Potentially Occurring at Prince of Wales Island Remedial Investigation, Salt Chuck Mine -Tongass National Forest, Alaska Risk Assessment Work Plan Common Name Scientific Name Feeding Habits Habitat Alder Flycatcher American Robin American Wigeon Bald Eagle Barn Swallow Barrow's Goldeneye Belted Kingfisher Black Scoter Black Turnstone Black-bellied Plover Black-capped Chickadee Blackpoll Warbler Boreal Chickadee Boreal Owl Brant Brown Creeper Bufflehead Canada Goose Chestnut-backed Chickadee Chipping Sparrow Common Goldeneye Common Loon Common Merganser Common Raven Common Yellowthroat Dark-eyed J unco Double-crested Cormorant Downy Woodpecker Dunlin Fox Sparrow Glaucous-winged Gull Golden-crowned Kinglet Golden-crowned Sparrow Gray Jay Gray-crowned Rosy-Finch Great Blue Fleron Greater Scaup Greater Yellowlegs Green-winged Teal Hairy Woodpecker Harlequin Duck Hermit Thrush Herring Gull Hooded Merganser Horned Grebe Least Sandpiper Lesser Yellowlegs Lincoln's Sparrow MacGillivray's Warbler Mallard Marbled Murrelet Merlin Mew Gull Northern Flicker Empidonax alnorum Turdus migratorius Anus americana Haliaeetus leucocephalus Hirundo rustica Bucephala islandica Ceryle alcyon Melanitta americana Arenaria melanocephala Pluvialis squatarola Poecile atricapillus Setophaga striata Poecile hudsonicus Aegolius funereus Branta bernicla Certhia americana Bucephala albeola Branta canadensis Poecile rufescens Spizella passerina Bucephala clangula Gavia immer Mergus merganser Corvus corax Geothlypis trichas Junco hyemalis Phalacrocorax auritus Picoides pubescens Calidris a I pin a Passerella iliaca Larus glaucescens Regulus satrapa Zonotrichia atricapilla Perisoreus canadensis Leucosticte tephrocotis Ardea herodias Aythya marila Tringa melanoleuca Anas crecca Picoides villosus Histrionicus histrionicus Catharus guttatus Larus argentatus Lophodytes cucullatus Podiceps auritus Calidris minutilla Tringa flavipes Melospiza lincolnii Geothlypis tolmiei Anas platyrhynchos Brachyramphus marmoratus Falco columbarius Larus can us Colaptes auratus Insectivorous Omnivorous Omnivorous Carnivorous/scavenger Insectivorous Carnivorous Carnivorous Insectivorous Carnivorous Insectivorous Omnivorous Insectivorous Insectivorous Carnivorous Herbivorous Insectivorous Carnivorous Herbivorous Omnivorous Omnivorous Insectivorous Piscivorous Piscivorous Omnivorous/scavenger Insectivorous Herbivorous Piscivorous Insectivorous Carnivorous Herbivorous Carnivorous/scavenger Carnivorous Herbivorous Omnivorous Herbivorous Carnivorous Insectivorous Carnivorous Herbivorous Insectivorous Carnivorous Omnivorous Carnivorous/scavenger Piscivorous Piscivorous/insectivorous Insectivorous Insectivorous Herbivorous Herbivorous Omnivorous Carnivorous Carnivourous Carnivorous Insectivorous Stream banks/mixed deciduous-coniferous Coniferous/mixed deciduous- coniferous forests Rivers/lakes/estuaries Coniferous forests Rivers/lakes/estuaries Lakes/nearshore marine Rivers/lakes/estuaries Lakes/nearshore marine Intertidal Lakes/nearshore marine Coniferous/mixed deciduous- coniferous forests Coniferous/mixed deciduous- coniferous forests Coniferous/mixed deciduous- coniferous forests Coniferous/mixed deciduous- coniferous forests Lakes/intertidal wetlands Coniferous forests Lakes/nearshore marine Lakes/intertidal wetlands Coniferous/mixed deciduous- coniferous forests Coniferous/mixed deciduous- coniferous forests Lakes/nearshore marine Lakes/nearshore marine Lakes/streams Coniferous/mixed deciduous- coniferous forests Coniferous/mixed deciduous- coniferous forests Coniferous/mixed deciduous- coniferous forests Lakes/streams Coniferous/mixed deciduous- coniferous forests Coastal mudflats/sandy beaches Coniferous/mixed deciduous- coniferous forests Inshore/offshore/intertidal Coniferous forests Coniferous/mixed deciduous- coniferous forests Coniferous/mixed deciduous- coniferous forests Cliffs/rock piles Lakes/intertidal waters Rivers/lakes/estuaries Muskegs Lakes/intertidal wetlands Coniferous/mixed deciduous- coniferous forests Inshore/offshore/intertidal Coniferous/mixed deciduous- coniferous forests Inshore/offshore/intertidal Lakes/inshore marine waters Lakes/inshore marine waters Muskegs Lakes/intertidal waters Shrub communities/grasslands Coniferous/mixed deciduous- coniferous forests Lakes/inshore marine waters Inshore/offshore/intertidal Coniferous forests Inshore/offshore/intertidal Coniferous/mixed deciduous- coniferous forests ------- Table 4 Bird Species Potentially Occurring at Prince of Wales Island Remedial Investigation, Salt Chuck Mine -Tongass National Forest, Alaska Risk Assessment Work Plan Common Name Scientific Name Feeding Habits Habitat Northern Hawk Owl Surnia ulula Carnivorous Coniferous/mixed deciduous- coniferous forests Northern Pintail Anas acuta Omnivorous Lakes/intertidal waters Northern Saw-whet Owl Aegolius acadicus Carnivorous Coniferous/mixed deciduous- coniferous forests Northern Shoveler Anas clypeata Omnivorous Lakes/intertidal wetlands Northern Waterthrush Parkesia noveboracensis Insectivorous Coniferous/mixed deciduous- coniferous forests Northwestern Crow Corvus caurinus Omnivorous Coniferous/mixed deciduous- coniferous forests Olive-sided Flycatcher Contopus cooperi Insectivorous Coniferous forests Orange-crowned Warbler Vermivora celata Insectivorous Coniferous/mixed deciduous- coniferous forests Pacific Loon Gavia pacifica Carnivorous Lakes/inshore and offshore marine waters Pacific Wren Troglodytes pacificus Carnivorous Coniferous forests Pacific-slope Flycatcher Empidonax difficilis Carnivorous/Insectivorous Coniferous/mixed deciduous- coniferous forests Pelagic Cormorant Phalacrocorax pelagicus Carnivorous/Picivorous Inshore/offshore marine waters Pine Grosbeak Pinicola enucleator Herbivorous Coniferous forests Pine Siskin Carduelis pinus Herbivorous Coniferous/mixed deciduous- coniferous forests Red Crossbill Loxia curvirostra Herbivorous Coniferous/mixed deciduous- coniferous forests Red-breasted Merganser Mergus senator Piscivorous Lakes/nearshore marine Red-breasted Nuthatch Sitta canadensis Omnivorous Coniferous/mixed deciduous- coniferous forests Red-breasted Sapsucker Sphyrapicus ruber Carnivorous/Insectivorous Coniferous/mixed deciduous- coniferous forests Red-eyed Vireo Vireo olivaceus Insectivorous Coniferous/mixed deciduous- coniferous forests Red-necked Grebe Podiceps grisegena Carnivorous Nearshore marine/lakes and streams Red-throated Loon Gavia stellata Piscivorous Lakes/inshore and offshore marine waters Ring-necked Duck Aythya collaris Omnivorous Lakes/nearshore marine Ruby-crowned Kinglet Regulus calendula Carnivorous Coniferous/mixed deciduous- coniferous forests Rufous Flummingbird Selasphorus rufus Herbivorous Coniferous/mixed deciduous- coniferous forests Savannah Sparrow Passerculus sandwichensis Herbivorous Coniferous/mixed deciduous- coniferous forests Semipalmated Plover Charadrius semipalmatus Insectivorous Nearshore/lntertidal Sharp-shined Flawk Accipiter striatus Carnivorous Coniferous/mixed deciduous- coniferous forests Short-billed Dowitcher Limnodromus griseus Insectivorous Muskegs Song Sparrow Melospiza melodia Omnivorous Coniferous/mixed deciduous- coniferous forests Spruce Grouse Falcipennis canadensis Herbivorous Coniferous forests Steller's Jay Cyanocitta stelleri Omnivorous Coniferous/mixed deciduous- coniferous forests Surf Scoter Melanitta perspicillata Carnivorous Inshore/offshore/intertidal Surfbird Aphriza virgata Insectivorous Nearshore/lntertidal Swainson's Thrush Catharus ustulatus Omnivorous Coniferous forests Tennessee Warbler Oreothlypis peregrina Insectivorous Coniferous/mixed deciduous- coniferous forests Townsend's Solitaire Myadestes townsendi Omnivorous Coniferous forests Townsend's Warbler Dendroica townsendi Insectivorous Coniferous forests Tree Swallow Tachycineta bicolor Carnivorous/Insectivorous Coniferous/mixed deciduous- coniferous forests Trumpeter Swan Cygnus buccinator Herbivorous Inshore marine waters Varied Thrush ixoreus naevius Omnivorous Coniferous/mixed deciduous- coniferous forests Violet-green Swallow Tachycineta thalassina Insectivorous Coniferous/mixed deciduous- coniferous forests Warbling Vireo Vireo gilvus Insectivorous Coniferous/mixed deciduous- coniferous forests Western Sandpiper Calidris mauri Insectivorous Lakes/intertidal waters Western Screech Owl Megascops kennicottii Carnivorous Coniferous/mixed deciduous- coniferous forests Whimbrel Numenius phaeopus Insectivorous Nearshore/lntertidal White-crowned Sparrow Zonotrichia leucophrys Omnivorous Coniferous/mixed deciduous- coniferous forests White-winged Crossbill Loxia leucoptera Herbivorous Coniferous forests White-winged Scoter Melanitta fusca Piscivorous/insectivorous Lakes/inshore marine waters Wilson's Warbler Wilsonia pusilla Insectivorous Coniferous/mixed deciduous- coniferous forests Yellow Warbler Setophaga petechia Insectivorous Riparian areas/wetlands Yellow-rumped Warbler Dendroica coronata Insectivorous Coniferous/mixed deciduous- coniferous forests Source: Melissa Cady, Wildlife Biologist Prince of Wales Zone, Tongass National Forest ------- Table 5 Terrestrial and Marine Mammals Potentially Occurring at Prince of Wales Island Remedial Investigation, Salt Chuck Mine - Tongass National Forest, Alaska Risk Assessment Work Plan Common Name Scientific Name Feeding Habits Habitat Terrestrial Mammals American Marten Martes americana Carnivorous Coniferous forests American Mink Neovison vison Carnivorous Coniferous forests along streams Beaver Castor canadensis Herbivorous Streams and lakes in mixed deciduous-coniferous fores Black bear Ursus americanus Omnivorous Coniferous forests California myotis Myotis californicus Carnivorous/ insectivorous Caves/mine tunnels/tree cavities Dusky shrew Sorex monticolus Insectivorous Muskegs/coniferous forests/dry hillsides Ermine Mustela erminea Carnivorous Coniferous forests Gray wolf Canis lupis Carnivorous Coniferous forests House mouse Mus muscu/us Omnivorous Coniferous/mixed deciduous-coniferous forests Keen's myotis Myotis keenii Carnivorous/ insectivorous Caves/mine tunnels/tree cavities Keen's mouse Peromyscus keeni Granivorous Coniferous/mixed deciduous-coniferous forests Little brown bat Myotis lucifigus Carnivorous/ Insectivorous Caves/mine tunnels/tree cavities Long-legged myotis Myotis volans Carnivorous/ insectivorous Caves/mine tunnels/tree cavities Long-tailed vole Microtus longicaudus Herbivorous Coniferous/mixed deciduous-coniferous forests Northern flying squirrel Glaucomys sabrinus Herbivorous Coniferous/mixed deciduous-coniferous forests Norway rat Rattus norvegicus Omnivorous Coniferous/mixed deciduous-coniferous forests River otter Lontra canadensis Carnivorous Coniferous forests Sitka black-tailed deer Odocoileus hemionus sitkensis Herbivorous Coniferous forest/alpine/subalpine Marine Mammals Dall's porpoise Phocoenoides dalli Piscivorous Nearshore/offshore marine Gray whale Eschrichtius robustus Carnivor Offshore marine Harbor porpoise Phocoena phocoena Piscivorous Nearshore/offshore marine Harbor seal Phoca vitulina Piscivorous Nearshore/gravel beaches and rocky shores (haulouts) Humpback whale Megaptera novaeangliae Planktivorous Nearshore/offshore marine Killer whale Orcinus orca Piscivorous Nearshore/offshore marine Minke whale Balaenoptera acutorostrata Planktivorous Nearshore/offshore marine Pacific white-sided dolphin Lagenorhynchusobliquidens Piscivorous Offshore marine Sea otter Enhydra lutris Piscivorous Nearshore/offshore marine Steller's sea lion Eumetopias jubatus Piscivorous Offshore/rocky shores (haulouts) ------- ------- Table 6 Exposure Assumptions for the Human Health Risk Assessment Remedial Investigation, Salt Chuck Mine -Tongass National Forest, Alaska Risk Assessment Work Plan Exposure Parameter Units Intermittent or Seasonal Worker Source Recreational User Source Customary /Traditional User Source Exposure Concentration (soil/sediment) mg/kg-dry 95% UCL of mean a 95% UCL of mean a 95% UCL of mean a Exposure Concentration (surface water) ug/L - - 95% UCL of mean a 95% UCL of mean a Exposure Concentration (shellfish tissue) mg/kg-wet - - 95% UCL of mean a 95% UCL of mean a Adult Body Weight kg 70 b 70 b 70 b Child Body Weight kg - - 15 b 15 b Exposure Frequency days/yr 125 c TBD - TBD - Adult Exposure Duration yrs 25 b 24 b 24 b Child Exposure Duration yrs - - 6 b 6 b Inhalation Exposure Time Fraction unitless 0.33 d 0.17 d 0.17 d Carcinogenic Averaging Time yrs 70 b 70 b 70 b Noncarcinogenic Averaging Time yrs 25 b 30 b 30 b Adult Incidental Soil/Sediment Ingestion Rate mg/day-dry 100 b 100 b 100 b Child Incidental Soil/Sediment Ingestion Rate mg/day-dry - - 200 b 200 b Adult Water Ingestion Rate L/day - - 0.05 e 0.05 e Child Water Ingestion Rate L/day - - 0.05 e 0.05 e Wild Food Consumption Rate g/day-wet - - TBD - TBD - Adult Skin Surface Area (soil) 2 cm 3,300 f 5,700 f 5,700 f Child Skin Surface Area (soil) 2 cm - - 2,800 f 2,800 f Adult Skin Surface Area (water) 2 cm - - 18,000 f 18,000 f Child Skin Surface Area (water) 2 cm - - 6,600 f 6,600 f Dermal Absorption Fraction (from soil/sediment) unitless Chemical-specific f Chemical-specific f Chemical-specific f Dermal Permeability Coefficient (water) cm/hr - - Chemical-specific f Chemical-specific f Adult Event Duration (water) hr/event - - 1.0 g 1.0 g Child Event Duration (water) hr/event - - 1.0 g 1.0 g Adult Soil-to-Skin Adherence Factor mg/cm2 0.2 f 0.07 f 0.07 f Adult Sediment-to-Skin Adherence Factor mg/cm2 - - 0.3 f,h 0.3 f,h Child Soil-to-Skin Adherence Factor mg/cm2 - - 0.2 f 0.2 f Child Sediment-to-Skin Adherence Factor mg/cm2 - - 3.3 f,h 3.3 f,h Particulate Emission Factor m3/kg 1.32E+09 i 1.32E+09 i 1.32E+09 i Volatilization Factor m3/kg Chemical-specific i Chemical-specific i Chemical-specific i Notes: TBD - to be determined prior to the risk assessment cm2 - square centimeters days/yr - days per year kg - kilograms m3/kg - cubic meters per kilogram UCL - upper confidence limit a. Based on 2011, 2012, and 2013 Rl sampling b. Risk Assessment Guidance for Superfund, Volume 1, Human Health Evaluation Manual. Supplemental Guidance: Standard Default Exposure Factors (EPA 1991a) mg/cm2 - milligrams per square centimeter mg/day - milligrams per day mg/kg - milligrams per kilogram mg/L- milligrams per liter yrs - years ------- c. Based on the assumption that mining operations in remote Alaska may hypothetically use a two-weeks-on and two-weeks-off work schedule (Personal communication, Anne Marie Palmieri/ADEC February 2013). Ir addition to the hypothetical future worker scenario, a reasonable current case worker scenario (e.g., forester) may be included to inform risk management decisions. d. Fraction of exposure time applied to calculation of inhalation risk (worker equates to 8 hr/day, recreational/subsistence user equates to 4 hr/day) e. Risk Assessment Guidance for Superfund, Volume 1, Human Health Evaluation Manual (Part A), Interim Final (EPA 1989). Exposure estimates will be based on unfiltered water sample results f. Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment) Final (EPA 2004). Surface areas are based on whole body for water, anc head, hands, forearms, and lower legs for soil/sediment. g. Professional judgment. Assumes a one-hour swimming or contact event per day, h. From Exhibit 3-3 in EPA 2004. Value for residential adults as gardeners and value for children playing in wet soil i. Soil Screening Guidance: Users Guide (EPA 1996a). ------- Table 7 Toxicity Factors for the Hu man Health Risk Assessment Remedial Investigation, Salt Chuck Mine -Tongass National Forest, Alaska Risk Assessment Work Plan Water Permeability Volatilizat Dermal Gl Inhalation Unit Oral Reference Inhalation Reference Mutagen Constant (Kp) ion Factor Absorption Absorption Oral Slope Factor Risk Dose Concentration (RfC) Analyte CASRN (Y/N) (cm/hr) (m3/kg) Fraction Fraction (mg/kg-day)'1 Source (ug/m3) Source (mg/kg-day) Source (mg/m3) Source Aluminum 7429-90-5 1.0E-03 1 1.0E+00 5.0E-03 P Antimony 7440-36-0 1.0E-03 0.15 4.0E-04 Arsenic 7440-38-2 1.0E-03 0.03 1 1.5E+00 4.3E-03 3.0E-04 1.5E-05 C Barium 7440-39-3 1.0E-03 0.07 2.0E-01 5.0E-04 H Beryllium 7440-41-7 1.0E-03 0.007 2.4E-03 2.0E-03 2.0E-05 1 Cadmium (Diet) 7440-43-9 1.0E-03 0.001 0.025 1.8E-03 1.0E-03 2.0E-05 A Cadmium (Water) 7440-43-9 1.0E-03 0.001 0.05 1.8E-03 5.0E-04 2.0E-05 A Chromium, Total 7440-47-3 1.0E-03 0.013 Chromium (III) 16065-83-1 1.0E-03 0.013 1.5E+00 Chromium (VI) 18540-29-9 M 2.0E-03 0.025 5.0E-01 8.4E-02 3.0E-03 1.0E-04 1 Cobalt 7440-48-4 4.0E-04 1 9.0E-03 3.0E-04 6.0E-06 P Copper 7440-50-8 1.0E-03 1 4.0E-02 H Iron 7439-89-6 1.0E-03 1 7.0E-01 Manganese (Diet) 7439-96-5 1.0E-03 1 1.4E-01 5.0E-05 1 Manganese (Non-diet) 7439-96-5 1.0E-03 0.04 2.4E-02 5.0E-05 1 Mercury 7439-97-6 1.0E-03 0.07 3.0E-04 3.0E-04 S Methyl mercury 22967-92-6 1.0E-03 1 1.0E-04 Molybdenum 7439-98-7 1.0E-03 1 5.0E-03 Nickel 7440-02-0 2.0E-04 0.04 2.6E-04 C 2.0E-02 9.0E-05 A Aroclor 1260 11096-82-5 9.9E-01 0.14 1 2.0E+00 5.7E-04 Acenaphthene 83-32-9 8.6E-02 1.51E+05 0.13 1 6.0E-02 Anthracene 120-12-7 1.4E-01 5.63E+05 0.13 1 3.0E-01 Benz(a)anthracene 56-55-3 M 5.5E-01 0.13 1 7.3E-01 1.1E-04 C Benzo(a)pyrene 50-32-8 M 7.1E-01 0.13 1 7.3E+00 1.1E-03 c Benzo(b)fluoranthene 205-99-2 M 4.2E-01 0.13 1 7.3E-01 1.1E-04 c Benzo(k)fluora nthene 207-08-9 M 6.9E-01 0.13 1 7.3E-02 1.1E-04 c Chrysene 218-01-9 M 6.0E-01 0.13 1 7.3E-03 1.1E-05 c Dibenz[a,h]anthracene 53-70-3 M 9.5E-01 0.13 1 7.3E+00 1.2E-03 c Fluoranthene 206-44-0 3.1E-01 0.13 1 4.0E-02 Fluorene 86-73-7 1.1E-01 3.03E+05 0.13 1 4.0E-02 lndeno[l,2,3-cd]pyrene 193-39-5 M 1.0E+00 0.13 1 7.3E-01 1.1E-04 c 2-Methyl naphthalene 91-57-6 9.2E-02 6.24E+04 0.13 1 4.0E-03 Naphthalene 91-20-3 4.7E-02 4.99E+04 0.13 1 3.4E-05 c 2.0E-02 3.0E-03 1 Pyrene 129-00-0 2.0E-01 2.56E+06 0.13 1 3.0E-02 Selenium 7782-49-2 1.0E-03 1 5.0E-03 2.0E-02 C Silver 7440-22-4 6.0E-04 0.04 5.0E-03 Thallium 7440-28-0 1.0E-03 1 1.0E-05 X Vanadium 7440-62-2 1.0E-03 1 5.0E-03 1.0E-04 A Zinc 7440-66-6 6.0E-04 1 3.0E-01 Notes: CASRN = Chemical Abstract System Registry Number Sources: A - Agency for Toxic Substances and Disease Registry (ATSDR) C - California Environmental Protection Agency (CAEPA) E - Environmental Criteria and Assessment Office (ECAO) H - Health Effects Assessment Summary Tables (HEAST) Notes (continued): Kp values from the EPA Estimation Program Interface (EPI) Suite database. EPA Nov 2012 regional screening levels (RSLs) and volatilization factors (VFs). Cancer slope factors and inhalation unit risks (lURs) for carcinogenic polynuclear aromatic hydrocarbons (PAHs) were weighted according to their respective benzo(a)pyrene toxicity equivalency factors (TEFs) using the scheme of EPA's Provisional Guidance for Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons (EPA, 1993a). I - Integrated Risk Information System (IRIS) S = RSL user guide Section 5 P - Provisional Peer-Reviewed Toxicity Values (PPRTV) X-PPRTV Appendix m3/kg = cubic meters per kilogram; mg/kg = milligrams per kilogram; ug/m3 = micrograms per cubic meter; mg/m3 = milligrams per cubic meter ------- ------- TABLE 8 Assessment and Measurement Endpoints for the Ecological Risk Assessment Risk Assessment Work Plan, Remedial Investigation, Salt Chuck Mine, Tongass National Forest, Alaska Representative Endpoint Functional Group Assessment Endpoint Species Aquatic Organisms Benthic and Epibenthic Organisms Survival and health of freshwater and marine/estuarine aquatic organisms using water bodies at or down- gradient of Salt Chuck Mine, and potentially exposed to constituents in surface water and prey items Survival and health of benthic and epibenthic organisms using water bodies at and down-gradient of Salt Chuck Mine, and potentially exposed to constituents in sediment Freshwater and marine fish, amphibians, and aquatic invertebrates Benthic macroinvertebrates, clams and other shellfish Terrestrial Invertebrates Herbivorous Birds Carnivorous bird) Omnivorous Birds Survival and health of terrestrial invertebrates at and down-gradient of Salt Chuck Mine, and potentially exposed to constituents in soil Survival and health of herbivorous birds using areas with suitable habitat, and potentially exposed to constituents in surface water, soil/sediment and forage items Survival and health of carnivorous birds using areas with suitable habitat, and potentially exposed to constituents in surface water, soil and prey items Survival and health of omnivorous birds using areas with suitable habitat, and potentially exposed to constituents in surface water, soil and forage items Terrestrial invertebrates Spruce grouse (upland/riparian), mallard (intertidal) Northern shrike (upland) Chestnut-backed chickadee (upland) Insectivorous Birds Piscivorous Birds Carnivorous Mammals Survival and health of insectivorous birds using areas with suitable habitat, and potentially exposed to constituents in soil/sediment and prey items Survival and health of piscivorous birds using areas with suitable habitat, and potentially exposed to constituents in surface water, sediment and prey items Survival and health of carnivorous mammals using areas with suitable habitat, and potentially exposed to constituents in surface water, soil and prey items Common snipe (riparian), western sandpiper (intertidal) Belted kingfisher (intertidal) Gray wolf (upland) Measure of Exposure Measure of Effect Measured constituent levels in surface water Measured constituent levels in sediment and shellfish tissue; exposure levels used during sediment bioassay testing. Measured constituent levels in soil Measured constituent levels in surface water, soil/sediment, plant tissue Measured constituent levels in surface water and soil; modeled constituent levels in food items Measured constituent levels in surface water, soil, and plant tissue; modeled constituent levels in food items Measured constituent levels in soil/sediment; modeled constituent levels in food items Measured constituent levels in surface water, sediment and shellfish tissue Measured constituent levels in surface water and soil; modeled constituent levels in food items Federal and state water quality criteria/standards Freshwater (for example, TECs and PECs) and marine sediment (for example, ER-Ms and AETs) benchmarks from literature, tissue-residue effects levels from literature, and site-specific sediment bioassay results Terrestrial invertebrate benchmarks from literature (for example, Eco SSLs) Literature-based chronic LOAEL for bird populations and NOAEL for T&E species* Literature-based chronic LOAEL for bird populations and NOAEL for T&E species* Literature-based chronic LOAEL for bird populations and NOAEL for T&E species* Literature-based chronic LOAEL for bird populations and NOAEL for T&E species* Literature-based chronic LOAEL for bird populations and NOAEL for T&E species* Literature-based chronic LOAEL for mammal populations and NOAEL for T&E species* ------- TABLE 8 Assessment and Measurement Endpoints for the Ecological Risk Assessment Risk Assessment Work Plan, Remedial Investigation, Salt Chuck Mine, Tongass National Forest, Alaska Representative Endpoint Functional Group Assessment Endpoint Species Measure of Exposure Measure of Effect Herbivorous Mammals Omnivorous Mammals Insectivorous Mammals Piscivorous Mammals Terrestrial, Riparian and Intertidal Vegetation Survival and health of herbivorous mammals using areas with suitable habitat, and potentially exposed to constituents in surface water, soil and forage items Survival and health of omnivorous mammals using areas with suitable habitat, and potentially exposed to constituents in surface water, soil/sediment, and prey/forage items Survival and health of insectivorous mammals using areas with suitable habitat, and potentially exposed to constituents in surface water, sediment and prey items Sitka black-tailed deer (upland) Black bear (upland/intertidal) Northern water shrew (riparian) Survival and health of piscivorous mammals using areas Mink (intertidal) with suitable habitat, and potentially exposed to constituents in surface water, sediment and prey items Survival and health of plants within the Salt Chuck Mine area, and potentially exposed to constituents in soil/sediment Various Plants Measured constituent levels surface water, soil, and plant tissue Measured constituent levels in surface water, soil, plant tissue; modeled constituent levels in prey items Measured constituent levels in surface water, sediment; modeled constituent levels in food items Measured constituent levels in surface water, sediment and shellfish tissue Measured constituent levels in soil/sediment Literature-based chronic LOAEL for mammal populations and NOEAL for T&E species* Literature-based chronic LOAEL for mammal populations and NOAEL for T&E species* Literature-based chronic LOAEL for mammal populations and NOAEL for T&E species* Literature-based chronic LOAEL for mammal populations and NOAEL for T&E species* Available plant benchmarks from literature sources Notes: * = As described in Section 2.3.4, no T&E species are expected to use the Salt Chuck Mine site and therefore, will not be evaluated as part of this ERA. If T&E species are identified during the Rl, then they will be addressed in the ERA. NOAEL = no observed adverse effect level LOAEL = lowest observed adverse effect level TEC = threshold effect concentration (MacDonald et al., 2000) PEC = probable effect concentration (MacDonald et al., 2000). ER-M = effects range-median (Long and Morgan, 1990) AET = apparent effects threshold (Buchman, 2008) Eco SSL = EPA's Ecological Soil Screening Level (Long and Morgan, 1990) ------- Table 9 Exposure Factors for Bird and Mammal Endpoint Species Remedial Investigation, Salt Chuck Mine-Tongass National Forest, Alaska Risk Assessment Work Plan Assumed Diet Composition Assessment Endpoint Functional Group Endpoint Species Body Weight (kg) Source Food Intake (kg/kj bw/d, dw) ' Water Intake2 (L/kg-bw/d) Migration Factor4 Home Range (acres) Source % of Diet as Mammals/ Birds % Diet as Terrestrial Invertebrates % Diet as Aquatic Invertebrates % of Diet as Plants % of Diet as Fish/ Shellfish % of Diet as Soil/ Sediment Surrogate for % of Diet as Soil/Sediment Source Herbivorous birds Spruce Grouse 0.525 Cornell, 2013 0.094 0.073 521 USFWS 2010 0 0 0 100 0 9.3 Wild turkey Beyer, 1994 Herbivorous birds Mallard 1.16 USEPA, 1993 0.609 0.056 1433 EPA 1993 0 0 8 92 0 3.3 Beyer, 1994 Omnivorous birds Chestnut-backed Chickadee 0.0115 ADFG, 2013a 2.595 0.258 3.3 Zeiner et al., 1990 0 80 0 20 0 2 2% for omnivores Beyer, 1994 Insectivorous birds Western Sandpiper 0.028 Cornell, 2013 1.192 0.192 0.62 EPA 1993 (Spotted Sandpiper surrogate) 0 0 100 0 0 18 Beyer, 1994 Carnivorous birds Northern Shrike 0.0675 Cornell, 2013 2.106 0.144 11 Zeiner et al., 1990 (Loggerhead Shrike surrogate) 100 0 0 0 0 0.7 Bald Eagle Pascoe et al., 1996 Piscivorous birds Belted Kingfisher 0.155 Cornell, 2013 1.591 0.109 2.50 EPA 1993 0 0 0 0 100 0.7 Bald Eagle Pascoe et al., 1996 Herbivorous mammals Sitka black-tailed deer 45.4 ADFG, 2013b 0.208 0.068 145 Sample et al., 1997 0 0 0 100 0 <0.2 Mule deer Beyer, 1994 Omnivorous mammals Black bear 86.2 ADFG, 2013b 0.103 0.063 6400 NPS, 2013 503 0 0 50 503 9.4 Raccoon Beyer, 1994 Insectivorous mammals Dusky shrew 0.007 Olori, 2005 2.434 0.163 0.96 EPA 1993 (short-tailed shrew surrogate) 0 100 0 0 0 2.4 Meadow vole Beyer, 1994 Carnivorous mammals Gray wolf 45.4 ADFG, 2013b 0.081 0.068 83,200 Montana Field Guide, 2013 80 0 0 0 20 2.8 Red fox Beyer, 1994 Piscivorous mammals Mink 0.852 USEPA, 1993 0.157 0.101 554 EPA 1993 0 0 0 0 100 9.4 Raccoon Beyer, 1994 Notes: 1 = Nagy (2001) regression equation for food ingestion rate (grams dry matter ingested/day/gram body weight = ( a x BW° )/BW; Note: values for a and b are presented below L = The allometric equations provided in Calder and Braun (1983) as cited in Sample et. al. (1997) were used to estimate daily water ingestion rates for each receptor species, as follows: • Water ingestion rate for all birds (L/day) = (0.059 * BWU 0/)/BW • Water ingestion rate for all mammals (L/day) = (0.099 * BWu yu)/BW BW = body weight DW = dry weight TBD = to be determined through additional literature research 3 = Assumes 50% birds and mammals and 50% terrestrial plants for upland exposure scenario; assumes 50% fish/shellfish and 50% aquatic plants for intertidal exposure scenarios 4 = Initially assumed to be present 100% of the year EPA = United States Environmental Protection Agency Group a b Birds Passerines 0.630 0.683 Chickadee All Birds 0.638 0.685 Mallard Galliformes 0.088 0.891 Grouse Charradriiformes 0.522 0.769 Sandpiper Carnivorous birds 0.849 0.663 Shrike, Kingfisher Mammals Herbivorous mammals 0.859 0.628 Deer Omnivorous mammals 0.432 0.678 Bear Insectivorous mammals 0.373 0.622 Shrew Carnivorous mammals 0.153 0.834 Wolf, Mink Table References: Sample, B.E., M.S. Aplin, R.A. Efroymson, G.W. Suter and C.J. Welsh. 1997. Methods and tools for estimation of the exposure of terrestrial wildlife to contaminants. ORNL/TM-13391 Beyer, W.N., E.E .Connor and S. Gerould. 1994. Estimates of Soil Ingestion by Wildlife. Allen Press, Lawrence, KS. Nagy, K.A. 2001. "Food Requirements of wild Animals: Predictive Equations for Free-Living Mammals, Reptiles, and Birds." Nutrition Abstracts and Reviews Series B: Livestock Feeds and Feeding. Vol. 71, No. 10. Pascoe, G.A., R.J. Blancher, and G. Linder. 1996. "Food Chain Analysis of Exposures and Risks to Wildlife at a Metals-contaminated Wetland." Archives of Environmental Contamination and Toxicology. Volume 30. Pages 306 through 318. EPA. 1993. "Wildlife Exposure Factors Handbook." USEPA/600/R-93/187a. December. - and sources cited within. ADFG, 2013a. Alaska Department of Fish and Game. http://www.adfg.alaska.gov/index.cfm?adfg=animals.listbirds ADFG, 2013b. Alaska Department of Fish and Game. http://www.adfg.alaska.gov/index.cfm?adfg=animals.listmammals Cornell, 2013. http://www.birds.Cornell.edu/Page.aspx?pid=1478 USFWS. 2010. Species Assessment and Listing Priority Assignment Form - Falcipennis canadensis isleibi. September 23, 2010 NPS. 2013. National Park Service Website for Black Bears. Available at: http://www.nps.gov/romo/naturescience/black_bears.htm Montana Field Guide. 2013. Montana Natural Heritage Program and Montana Fish, Wildlife and Parks. Retrieved on May 16, 2013, from http://FieldGuide.mt.gov/detail_AMAJA01030.aspx J. Olori, 2005, "Sorex monticolus" (On-line), Digital Morphology. Accessed May 16, 2013 at http://digimorph.org/specimens/Sorex_monticolus/whole/. Zeiner, D.W., Laudenslayer, Jr., Mayer, K.E., and White, M., 1990. California's Wildlife, Volume II, Birds. California Department of Fish and Game. November 1990. ------- ------- |