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

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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
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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
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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
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V

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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
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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

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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
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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*

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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
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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
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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).
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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

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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

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See SJubunit HcJnset Maps
es
on Following Pa
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Chuck Mine
Salt Chi^ck
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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.

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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.

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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.

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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
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Ingestion of
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a. Includes aboveground fuel storage tanks, battery banks, and other upland sources associated with historic mining operations.

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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
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Surface Runoff
Direct Discharge
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Lake Ellen Creek
Unnamed Creek
Lake Ellen Creek
Unnamed Creek
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Inhalation
Ingestion of
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a. Includes aboveground fuel storage tanks, battery banks, and other upland sources associated with historic mining operations.

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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

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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

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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
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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.
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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
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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
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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
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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.
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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
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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„
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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
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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
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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
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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
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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
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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
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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
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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).
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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
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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
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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)
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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,
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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
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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.
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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.
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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).
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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.
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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
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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.
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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).
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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.
ADEC (Alaska Department of Environmental Conservation). 2011. Risk Assessment Procedures Manual-Draft. ADEC,
Division of Spill Prevention and Response, Contaminated Sites Program, Anchorage, Alaska.
ADFG (Alaska Department of Fish and Game). 2013a. Community Subsistence Information System - Online
Database. http://www.subsistence.adfg.state.ak.us/CSIS/.
ADFG (Alaska Department of Fish and Game). 2013b. Alaska Department of Fish and Game - Mammals.
http://www.adfg. alaska.gov/index.cfm?adfg=animals. list mam ma Is.
ADFG (Alaska Department of Fish and Game). 2013c. Alaska Department of Fish and Game - Birds.
http://www.adfg. alaska.gov/index.cfm?adfg=animals. list birds.
ADNR (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.
ANHB (Alaska Native Health Board). 2004. 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. September 24, 1986.
EPA. 1989. Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual (Part A), Interim
Final (RAGS). U.S. Environmental Protection Agency. EPA/540-1-89/002.
ES011013043021SEA
7-1

-------
7 REFERENCES
EPA. 1991a, Human Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure Factors. U.S.
Environmental Protection Agency. OSWER Directive No. 9285.6-03, March 25, 1991.
EPA. 1991b. Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions, U.S. Environmental
Protection Agency. OSWER Directive 9355.0-30, April 22, 1991.
EPA. 1991c. Ecological Assessment of Superfund Sites: an Overview. U.S. Environmental Protection Agency. Office
of Solid Waste and Emergency Response, Eco Update. Vol. 1, No. 2, Publication 9345.0-051. December.
EPA. 1991d. The Role of the BTAGs in Ecological Assessment. U.S. Environmental Protection Agency. Office of Solid
Waste and Emergency Response, Eco Update. Vol. 1, No. 1, Publication 9345.0-051, September.
EPA. 1992a .Supplemental Guidance to RAGS: Calculating the Concentration Term. Publication 9285.7-081. U.S.
Environmental Protection Agency. Office of Solid Waste and Emergency Response. May.
EPA. 1992b. Framework for Ecological Risk Assessment. U.S. Environmental Protection Agency. EPA/630/R-92/001.
EPA. 1992c. Briefing the BTAG: Initial Description of Setting, History, and Ecology of a Site. U.S. Environmental
Protection Agency. Office of Solid Waste and Emergency Response, Eco Update. Vol. 1, No. 5, Publication
9345.0-051. August.
EPA. 1992d. Developing a Work Scope for Ecological Assessments. U.S. Environmental Protection Agency. Office of
Solid Waste and Emergency Response, Eco Update. Vol. 1, No. 4, Publication 9345.0-051, May.
EPA. 1992e. The Role of the Natural Resource Trustees in the Superfund Process. U.S. Environmental Protection
Agency. Office of Solid Waste and Emergency Response, Eco Update. 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.
September 1994.
EPA. 1994c. Selecting and Using Reference Information in Superfund Ecological Risk Assessments. U.S.
Environmental Protection Agency. Office of Solid Waste and Emergency Response, Eco Update. Vol. 2, No.
4, Publication 9345.0-051, EPA 540-F-94-050. September.
EPA. 1994d. Using Toxicity Tests in Ecological Risk Assessment. U.S. Environmental Protection Agency. Office of
Solid Waste and Emergency Response, Eco-Update. Vol. 2, No. 1, Publication 9345.0-051, EPA 540-F-94-
012. September.
EPA. 1996a. Soil Screening Guidance: User's Guide. Second Edition. U.S. Environmental Protection Agency.
Publication 9355.4-23.
EPA. 1996b. Ecological Significance and Selection of Candidate Assessment Endpoints. U.S. Environmental
Protection Agency. Office of Solid Waste and Emergency Response, Eco Update. Vol. 3, No. 1, Publication
9345.0-051, EPA 540/F-95/037. January.
7-2
ES011013043021SEA

-------
7 REFERENCES
EPA. 1996c. Ecotox Thresholds. U.S. Environmental Protection Agency. Office of Solid Waste and Emergency
Response, Eco Update. Vol. 3, No. 2, Publication 9345.0-051, EPA 540/F-95/038. January.
EPA. 1997a. Interim Final Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting
Ecological Risk Assessments, Interim Final. U.S. Environmental Protection Agency. EPA/540/R-97/006.
EPA. 1997b. EPA Region 10 Supplemental Ecological Risk Assessment Guidance for Superfund. U.S. Environmental
Protection Agency Region 10. EPA 910-R-97-005. June.
EPA. 1998a. Methodology for Assessing Health Risks Associated with Multiple Pathways of Exposure to Combustor
Emissions. EPA/600/R-98/137. December.
EPA. 1998b. Guidelines for Ecological Risk Assessment. U.S. Environmental Protection Agency. Washington, D.C.
EPA/630/R-95/002F.
EPA. 1999. Ecological Risk Assessment and Risk Management Principles for Superfund Sites. U.S. Environmental
Protection Agency. OSWER Directive 92857.7-28P. October.
EPA. 2001. The Role of Screening-Level Risk Assessments and Refining Contaminants of Concern in Baseline
Ecological Risk Assessments. Office of Solid Waste and Emergency Response - EcoUpdate. U.S.
Environmental Protection Agency. EPA 540/ F-01/014. June.
EPA. 2002a, Guidance for Comparing Background and Chemical Concentrations in Soil for CERCLA Sites. U.S.
Environmental Protection Agency. EPA 540-R-01-003 OSWER 9285.7-41 September.
EPA. 2002b. Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites. U.S.
Environmental Protection Agency.
EPA. 2002c. National Recommended Water Quality Criteria: 2002 Human Health Criteria Calculation Matrix. U.S.
Environmental Protection Agency, Office of Water. EPA/822/R-02/012.
EPA. 2003a. Memorandum—Human Health Toxicity Values in Superfund Risk Assessments. U.S. Environmental
Protection Agency. OSWER Directive 9285.7-53. December 5, 2003.
EPA. 2003b. Calculation of PRGs, Appendix B of Adult Lead Methodology Guidance. U.S. Environmental Protection
Agency. EPA-540-R-03-001, OSWER Dir #9285.7-54.
EPA. 2004. Risk Assessment Guidance for Superfund Volume I: Human Health Evaluation Manual (Part E,
Supplemental Guidance for Dermal Risk Assessment) Interim. U.S. Environmental Protection Agency.
EPA/540/R/99/005.
EPA. 2005. Guidelines for Carcinogen Risk Assessment. U.S. Environmental Protection Agency. EPA/630/P-03/001B.
EPA. 2008. Integrated Risk Information System, Glossary of Terms. U.S. Environmental Protection Agency. Office of
Research and Development. http://www.epa.gov/irislRIS/
EPA. 2009a. Risk Assessment Guidance for Superfund-Volume I: Human Health Evaluation Manual (Part F,
Supplemental Guidance for Inhalation Risk Assessment). U.S. Environmental Protection Agency.
EPA. 2009b. National Recommended Water Quality Criteria. U.S. Environmental Protection Agency, Office of
Water, http://water.epa.gov/scitech/swguidance/standards/criteria/current/upload/nrwqc-2009.pdf
EPA. 2010a. ProUCL Version 4.1.00 Technical Guide: Statistical Software for Environmental Applications for Data
Sets with and without Nondetect Observations. U.S. Environmental Protection Agency. EPA/600/R-07-041.
May. http://www.epa.gov/osp/hstl/tsc/ProUCL_v4.l_tech.pdf
EPA. 2010b. Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK). Windows® version
(lEUBKwin vl.l build 11). U.S. Environmental Protection Agency. February.
EPA. 2011a. Exposure Factors Handbook, 2011 Edition. U.S. Environmental Protection Agency. Office of Research
and Development. EPA/600/R-09/052F. September.
ES011013043021SEA
7-3

-------
7 REFERENCES
EPA. 2011b. Software for Calculating Upper Confidence Limits (UCLs) ProUCL Version 4.1.01 [Online]
http://www.epa.gov/osp/hstl/tsc/software.htm U.S. Environmental Protection Agency. Updated July 12.
EPA. 2012a. Regional Screening Levels (RSLs) for Chemical Contaminants at Superfund Sites. U.S. Environmental
Protection Agency. November, http://www.epa.gov/region09/superfund/prg/index.html.
EPA. 2012b. Integrated Risk Information System, Integrated Risk Information System (IRIS) Database. U.S.
Environmental Protection Agency. Online database, http://www.epa.gov/iriswebp/iris/index.html.
EPA. 2013. IRIS. Integrated Risk Information System (IRIS) Database. EPA online database.
http://www.epa.gov/iriswebp/iris/index.html.
EPA. Various Dates 2003-2008. Ecological Soil Screening Level(EcoSSL) Guidance. U.S. Environmental Protection
Agency, Office of Research and Development. Online at: http://www.epa.gov/ecotox/ecossl/
Long, E.R. and L.G. Morgan. 1990. The Potential for Biological Effects of Sediment-Sorbed Contaminants Tested in
the National Status and Trends Program. NOAA Technical Memorandum NOS OMA 52.
Los Alamos National Laboratory. 2012.EcoRisk Database. Release 3.1. October.
Maas, K.E., P.E. Bittenbender, and J.C. Still. 1995. Mineral Investigations in the Ketchikan Mining District,
Southeastern Alaska. U.S. Dept. of Interior, Bureau of Mines, Open File Report 11-95. 606 pp.
MacDonald, D.D., C.G. Ingersoll, and T.A. Berger. 2000. "Development and Evaluation of Consensus-Based
Sediment Quality Guidelines for Freshwater Ecosystems." Archives of Environmental Contamination and
Toxicology 39: 20-31.
Michigan Department of Environmental Quality. 2009. Freshwater Chronic Values (FCV) from Rule 57 Water
Quality Values based on Rule 323.1057 (Toxic Substances) of the Part 4. December 2009.
http://www. michigan.gov/deq/0,1607,7-135-3313_3686_3728-11383—,00. html.
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.
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. 71:1R-12R.
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.
National Academy of Sciences. 2006. The Dietary Reference Intakes: The Essential Guide to Nutrient Requirements.
National Academy Press Online. J.J. Otten, J.P. Hellwig, and L.D. Meyers, Editors.
NOAA (National Oceanic and Atmospheric Administration). 2002. Tides Online. NOAA National Ocean Service,
Center for Operational Oceanographic Products and Services, www.co-ops.nos.noaa.gov
NOAA (National Oceanic and Atmospheric Administration). 2012. National Climate Data Center. Accessed October
1, 2012. http://www.ncdc.noaa.gov/cdo-web/.
North Wind. 2012. Near Final Completion Report Non-Time Critical Removal Action Salt Chuck Mine Mill Prince of
Wales IslandAlaska. Prepared for U.S. Forest Service. April.
NPS. 2013. National Park Service Website for Black Bears. Available at:
http://www.nps.gov/romo/naturescience/black_bears.htm .
Olori, J. 2005. "Sorex monticolus" (On-line), Digital Morphology. Accessed May 16, 2013 at
http://digimorph.org/specimens/Sorex_monticolus/whole/.
ORNL(Oak Ridge National Laboratory). 2011. Risk Assessment Information System (RAIS) online. Sponsored by the
U.S. Department of Energy (DOE), Office of Environmental Management, Oak Ridge National Laboratory.
http://rais.ornl.gov/
7-4
ES011013043021SEA

-------
7 REFERENCES
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, pp.
306-318.
Sample, B.E., D.M. Opresko, and G.W. Suter II, 1996. Toxicological Benchmarks for Wildlife: 1996 Revision.
ES/ER/TM-86/R3. Oak Ridge, Tennessee: Oak Ridge National Laboratory.
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.
Suter ll,G.W., R.A. Efroymson, B.E. Sample, and D.S.Jones. 2000. Ecological Risk Assessment for Contaminated
Sites. Lewis Publishers, Boca Raton, FL.
U.S. Army Center for Health Promotion and Preventive Medicine. 2009. Directorate of Toxicology Downloads,
USACHPPM TRV database. Available at: http://chppm-www.apgea.army.mil/tox/download.aspx. Accessed
October 2009.
United States Environmental Protection Agency. See EPA.
URS. 2007. Draft Report Engineering Evaluation/Cost Analysis (EE/CA) Salt Chuck Mine Tongass National Forest,
Alaska. Prepared by URS Group, Inc. Prepared for U.S. Department of Agriculture Forest Service, Alaska
Region. March.
URS. 2010. Final Report, Focused Upland Engineering Evaluation/Cost Analysis (EE/CA), Salt Chuck Mine, Tongass
National Forest, Alaska. April 2010.
USFWS (United States Fish and Wildlife Service). 2012. National Wetlands Inventory. Online Wetlands mapper. U.S.
Department of the Interior. http://www.fws.gov/wetlands/Data/Mapper.html.
USFWS. 2010. Species Assessment and Listing Priority Assignment Form - Falcipennis canadensis isleibi.
September 23, 2010.
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.
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Tables

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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

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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

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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

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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

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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

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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)

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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

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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).

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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

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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*

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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)

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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.

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