PREPARED FOR

U.S. ENVIRONMENTAL PROTECTION AGENCY

REGION I, BOSTON, MASSACHUSETTS

EPA Contract No. 68-W9-0036EPA Work Assignment No. 21-1PB8

EPA Project Officer: Diana KingEPA Work Assignment Manager: Jane Dolan

BARKHAMSTED-NEW HARTFORD LANDFILL SUPERFUND SITE

BASELINE RISK ASSESSMENT

PART II

ECOLOGICAL RISK ASSESSMENT

JANUARY 1996

PREPARED BY:

METCALF & EDDY, INC.WAKEFIELD, MASSACHUSETTS

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TABLE OF CONTENTS

PARTH ECOLOGICAL RISK ASSESSMENT

Page

1.0 INTRODUCTION AND SITE DESCRIPTION 1-1 1.1 Introduction 1-1 1.2 Site Description 1-2

2.0 METHODS 2-1

3.0 HAZARD IDENTIFICATION 3-1 3.1 Media of Concern 3-1 3.2 Contaminant Screening 3-3

3.2.1 Sediment 3-5 3.2.2 Surface Soil 3-8 3.2.3 Surface Water 3-10 3.2.4 Summary of Contaminants of Ecological Concern 3-12

3.3 Potential Ecological Receptors 3-12 3.3.1 Benthic Invertebrates 3-13 3.3.2 Fish 3-13 3.3.3 Amphibians 3-13 3.3.4 Reptiles 3-14 3.3.5 Mammals 3-15 3.3.6 Birds 3-16 3.3.7 Soil Invertebrates 3-17 3.3.8 Plants 3-17

3.4 Assessment and Measurement Techniques 3-18

4.0 EXPOSURE ASSESSMENT 4-1 4.1 Source Characterization and Selection of

Exposure Pathways 4-1 4.1.1 Plants 4-2 4.1.2 Animals 4-2

4.2 Fate and Transport Analysis 4-5 4.2.1 Poly cyclic Aromatic Hydrocarbons (PAHs) 4-5 4.2.2 Metals 4-7 4.2.3 Pesticides 4-11 4.2.4 Phenolics 4-12

4.3 Exposure Scenarios and Integrated Exposure Analysis 4-13 4.3.1 Benthic Invertebrates 4-13 4.3.2 Earthworm 4-13 4.3.3 Green Frog 4-14

4.3.4 Spotted Salamander 4-14 4.3.5 American Robin 4-15 4.3.6 Deer Mouse 4-15 4.3.7 Woodchuck 4-15 4.3.8 Mink 4-16 4.3.9 Beaver 4-16 4.3.10 Muskrat 4-16

4.4 Uncertainty Analysis 4-17

5.0 TOXICITY ASSESSMENT 5-1 5.1 Qualitative Dose-Response Assessment 5-1

5.1.1 Benthic/Aquatic Invertebrates 5-4 5.1.2 Earthworms 5-4 5.1.3 Amphibians 5-5 5.1.4 American Robin 5-7 5.1.5 Mammals 5-9

5.2 Hazard Indices 5-12 5.3 Uncertainty Analysis 5-12

6.0 RISK CHARACTERIZATION 6-1 6.1 Selection of Risk Characterization Methodology 6-1 6.2 Risk Assessment Characterization 6-1

6.2.1 Benthic/Aquatic Invertebrates 6-1 6.2.2 Earthworms 6-3 6.2.3 Amphibians 6-3 6.2.4 American Robin 6-4 6.2.5 Mammals 6-4

6.3 Hazard Indices 6-7 6.4 Uncertainty Analysis 6-8 6.5 Conclusions 6-9

7.0 REFERENCES 7-1

APPENDIX A Wildlife Data APPENDIX B Protected Species Correspondence

LIST OF FIGURES

ECOLOGICAL RISK ASSESSMENT

1-1 Site Location Map 1-2 Site Layout, 1993 1-3 Limits of Refuse 1-4 Wetland Delineation Map 3-1 Surface Water/Leachate Seep and Sediment Sample Locations 3-2 Soil Sample Locations and Potential Disposal Areas 3-3 Proposed Extent of Landfill Cap

LIST OF TABLES

ECOLOGICAL RISK ASSESSMENT

3-1 Soil, Surface Water and Sediment Samples - Evaluation for Exposure Potential 3-2 Contaminant Screening - Sediment 3-3 Contaminant Screening - Surface Soil 3-4 Contaminant Screening - Surface Water 3-5 Contaminants of Ecological Concern 4-1 Potential Exposure Pathways of Concern for Indicators Species 5-1 Hazard Quotients for Aquatic Invertebrates from Exposure to

Sediment 5-2 Hazard Quotients for Deer Mouse from Ingestion of Soil 5-3 Hazard Quotients for Woodchuck from Ingestion of Soil 5-4 Hazard Quotients for Beaver from Ingestion of Soil 5-5 Hazard Quotients for Mink from Ingestion of Soil 5-6 Hazard Quotients for Beaver from Ingestion of Sediment 5-7 Hazard Quotients for Mink from Ingestion of Sediment 5-8 Hazard Quotients for Deer Mouse from Dermal Absorption of Soil 5-9 Hazard Quotients for Woodchuck from Dermal Absorption of Soil 5-10 Hazard Quotients for Mink from Dermal Absorption of Soil 5-11 Hazard Quotients for Beaver from Dermal Absorption of Sediment 5-12 Hazard Quotients for Mink from Dermal Absorption of Sediment 5-13 Hazard Quotients for Woodchuck from Ingestion of Plant Tissue 5-14 Hazard Quotients for Muskrat from Ingestion of Plant Tissue 5-15 Hazard Indices for Indicator Species

Surface Water and

6-1 Number of Macroinvertebrates Detected during the Phase IA Site Characterization

SECTION 1.0

INTRODUCTION AND SITE DESCRIPTION

1.1 INTRODUCTION

The Barkhamsted-New Hartford Landfill Superfund Site is located approximately 20 miles

northwest of Hartford within the Farmington River Valley in the towns of Barkhamsted and New

Hartford, Connecticut (Figure 1-1). The landfill occupies much of a 98-acre parcel of land

owned by the Regional Refuse Disposal District #1 (RRDD #1) and has been used for solid

waste disposal since 1974 (O'Brien & Gere Engineers, Inc., [OBG], 1993). In 1993, landfill

operations were restricted to approximately 17 acres of the northern area of the RRDD #1

property (Figure 1-2) and refuse was being disposed on approximately 13 acres (OBG, 1993 see

Figure 1-3). Since 1988, the landfill has been utilized only for the disposal of bulky and non

processible wastes, such as construction and demolition debris, (OBG, 1993), as well as serving

as a community collection facility for recyclable materials. Leaf composting is also conducted

on the site. The site is surrounded mostly by undeveloped land, although some residential

properties are located adjacent to the RRDD #1 property. The Barkhamsted Town Garage

facility borders the RRDD #1 property to the northeast, as does U.S. Route 44, and the

Farmington River is located approximately 0.5 miles east of the site. A history of waste

handling at the site is presented in Section 1.0 of the Human Health Risk Assessment.

Media that were investigated as part of Remedial Investigation Phase 1A included surface water,

groundwater, leachate, surface sediment, surface soil, subsurface soil, ambient air, and

landfill/soil gas (OBG, 1993; OBG, 1994a). The risk assessment assumes that a presumptive

remedy consisting of a landfill cap, a leachate collection system, and a landfill gas collection

system will be installed as described hi the Engineering Evaluation/Cost Analysis (EE/CA)

(OBG, 1994b) and discussed hi Section 2.0 of the Human Health Risk Assessment. The

ecological risk assessment consists of six major sections:

1-1

1) Introduction and Site Description: provides information on history, physical features and natural resources

2) Objectives and Methods: defines the goal of the assessment and the guidelines under which the assessment is conducted

3) Hazard Identification: contaminants are screened to determine which are of ecological concern; indicator species and endpoints are selected

4) Exposure Assessment: includes characterization of contaminant source(s), selection of exposure pathways, fate and transport analysis, exposure scenarios and integrated exposure analysis, and uncertainty analysis

5) Toricity Assessment: includes identification of toxic endpoints for indicator species, quantitative dose-response assessment, and uncertainty analysis

6) Risk Characterization: includes selection and presentation of risk assessment characterization, uncertainty analysis, and conclusions.

1.2 SITE DESCRIPTION

Based on a survey of the site conducted by Metcalf & Eddy (M&E) and U.S. Environmental

Protection Agency (USEPA) biologists on 11 June 1993 and the qualitative ecological assessment

conducted by OBG (1993), the various features of the site are described. Except for the landfill

itself and the support areas, the site was covered by relatively mature forest, which provides

excellent habitat for a variety of wildlife. On the southern portion of the site, the overstory was

dominated by eastern hemlock (Tsuga canadensis). To the north, the forest was mixed and then

primarily deciduous. The borrow area (located off the southeast comer of the main landfill

area), where tree stumps and other vegetative debris were disposed, was unvegetated as was the

active part of the landfill (Figure 1-2). The inactive portion of the landfill was covered by

grasses, with small pockets of low shrubs in some locations. Areas around buildings were

unvegetated or consisted of mowed lawn. Wetlands at the site were small and consisted of two

sedimentation basins, a small emergent wetland area adjacent to one of the sedimentation basins,

and areas bordering an unnamed brook (Figure 1-4).

1-2

There were two sedimentation basins present on the site and one unnamed pond bordered the site

to the north (Figure 1-2). Sedimentation Basin #1 was approximately 50 by 100 feet in size.

No emergent or submergent growth was observed hi the basin during the 11 June 1993 site visit.

A drainage swale channeled water from the storage/borrow area and entered the southern portion

of the landfill from the east. The northern shore area of the basin had been recently disturbed

by a bulldozer and was unvegetated at the tune of the June 1993 site visit. To the east, west,

and south, woody scrub was located on the immediate border of the basin, with relatively

mature, mixed forest cover types beyond the scrubby growth.

Sedimentation Basin #2 was approximately 50 by 40 feet in size. Based on the June 1993 site

visit, no emergent or submergent growth was observed in the basin. A small emergent wetland

area dominated by cattail (Typha spp.) was located just northeast of the basin and was connected

to the basin by a short (3 to 4 foot) swale. A drainage swale channeled water from the

storage/borrow area entering the basin from the south. A combination of shrub and herbaceous

growth occurred on the upland border of the basin. Forested cover types were located to the

north and east of the basin; to the west and south were the landfill and borrow area,

respectively.

The unnamed pond was surrounded by forested habitats. Water depth was approximately 1 foot

at the fringes, but 2 to 3 feet deep toward the center. The rocky substrate was covered by a

layer of detritus. Two channels connected the pond to the unnamed brook but appeared to

channel water from the brook to the pond only during high flow periods.

The unnamed brook was generally 2 to 4 feet wide and 1 to 8 inches deep. Wider (up to 6 feet)

and deeper (up to 12 inches) pools were observed hi some locations during the June 1993 site

visit. Flow rates were variable (1 to 12 inches per second), ranging from minimal (in pooled

areas) to relatively swift (in steeper, rocky areas). The generally sandy/gravelly substrate of the

brook had little organic matter hi the sediments. Numerous rocks, covered with moss and algae

hi some locations, were present throughout the length of the stream channel. The brook passed

through relatively mature forested habitats, dominated by conifers on the southern portion of the

1-3

site and by deciduous trees on the northern portion of the site, and the dense canopy (canopy

cover from 75 to 90 percent) effectively shaded the brook. Downgradient of the landfill, two

outfalls (OF-1 and OF-2) entered the brook (Figure 1-2). These outfalls were connected to

approximately 25 catch basins located along the main access roads to the landfill and recycling

areas, in the area containing the offices and recycling facilities, and on the Barkhamsted Town

Garage property (OBG, 1993).

1-4

SECTION 2.0

METHODS

The ecological risk assessment was conducted based on guidance provided in USEPA (1989a),

USEPA (1989c) and USEPA (1992). The hazard identification process allowed the various

contaminants and media to be preliminarily screened, thereby identify ing potential chemicals and

media of concern. Hazard identification and the selection of sensitive receptors were conducted

under the assumption that the presumptive remedy consisting of a cap and a leachate and landfill

gas collection system will be implemented. The presumptive remedy will limit the area under

consideration to sites outside of the proposed cap and eliminate exposures to some media outside

of the boundary of the cap as detailed in Section 3.1. Hazard identification involved the

following:

• A review of Remedial Investigation Phase 1A - Round 1 and Round 2 analytical data (OBG, 1993; OBG, 1994a) from on-site sampling of environmental media to determine the nature and extent of contamination.

• A review of the soil and surface water analytical data collected on-site during the Site Investigation (Fuss & O'Neill, 1991). These data were used for reporting site maximums only. The more recent and comprehensive set of samples collected by OBG (1993; 1994a) were used to generate average concentrations, detection frequencies, and number of exceedances of screening levels.

• An assessment of the toxicity, bioavailability, and bioconcentration, bioaccumulation, and biomagnification potential of the detected contaminants to determine if existing levels in particular media are known to cause adverse effects to ecological receptors.

• A brief assessment of the types of organisms and habitats present on-site and in areas potentially affected by migration of site contaminants in order to identify sensitive ecological receptors. This was accomplished by reviewing existing data collected by O'Brien and Gere during Phase 1A studies (OBG, 1993; OBG, 1994a) and conducting a brief site reconnaissance survey on 11 June 1993.

Exposure assessment included identification of exposure pathways based on the fate and transport

characteristics of chemicals of concern and the life histories of observed or likely inhabitants of

2-1

the site. Indicator species or species groups were selected to represent a range of trophic levels

and life history patterns. Exposure scenarios were outlined in detail for indicator species and

then quantified. Estimates of exposure were compared against toxicity reference values to obtain

pathway- and species-specific hazard quotients. Hazard quotients and hazard indices were used

to characterize and evaluate the potential risks to ecological resources at die site. Uncertainties

associated with the ecological risk assessment were discussed.

2-2

SECTION 3.0

HAZARD IDENTIFICATION

Section 3.0 includes a discussion of the site media of concern, and the presentation of the

contaminant screening process. Potential ecological receptors are discussed and indicator species

and species groups are selected. At the end of the section, assessment and measurement

endpoints are defined.

3.1 MEDIA OF CONCERN

Media that were investigated as part of Phase 1A investigations included surface water,

groundwater, leachate, surface sediment, surface soil, subsurface soil, ambient air, and

landfill/soil gas. Groundwater and subsurface soils (soils at depths greater than two feet) were

eliminated as media of ecological concern because potential indicator species have little direct

contact with these media. The hazard identification and exposure assessment were written under

the assumption that a presumptive remedy consisting of a cap, leachate collection system, and

gas collection system will be employed (OBG, 1994b). Based on the assumption of a

presumptive remedy, the following media and analytical data were excluded from consideration:

• Surface soil samples and shallow boring samples (less than two feet) from within proposed cap perimeter - regraded waste will be inaccessible under the cap

• All leachate samples - leachate is to be diverted to the collection system so seeps are expected to dry up

• Surface water samples from storm drams and catch basins - surface water is expected to improve after installation of the cap and leachate collection system

• Seep sediment samples from within the proposed cap perimeter - regraded waste will be inaccessible under the cap

• Surface water and sediment samples from the sedimentation basins - sedimentation basins will be regraded

3-1

• All landfill soil gas and vapor samples - impacts of the landfill on ambient air, following capping, are not evaluated in this assessment; it is expected that the need for remediation of landfill gases will be determined by sampling vented gas

Based on the presumptive remedy and likely exposure pathways for faunal and floral species

observed or expected to occur on-site, the following media are of potential concern to ecological

resources:

• Surface sediment in the unnamed brook and unnamed pond

• Surface water in the unnamed brook and unnamed pond

• Surface soil (0-2 feet) outside the boundary of the proposed cap

• Soil in leachate seeps outside the boundary of the proposed cap - will be dry due to the leachate collection system and cap

Surface water, sediment, and soil samples were collected hi 1992 and 1993 (OBG, 1993; OBG,

1994a). The locations of surface water and sediment samples are depicted in Figure 3-1. Soil

sampling locations are shown in Figure 3-2. Sample locations were chosen to characterize media

quality and to enable the identification of current and potentially adverse impacts of the landfill

on ecological resources inhabiting the site and surrounding area. Sample locations are described

in the Remedial Investigation reports (OBG, 1993; OBG, 1994a). Selection of sample locations

to be included in the risk assessment (Table 3-1) was based on the proposed extent of the landfill

cap (Figure 3-3) and the potential effects of the proposed cap on the quality and accessibility of

media (see above bullets regarding data and media included and excluded from the risk

assessment). Sediment, surface water, and soil sample locations included hi the ecological risk

assessment are identical to those used in the human health risk assessment. Analytical data from

sample locations in which an exposure potential could not be ruled out were included hi the

contaminant screening process. These included sample locations at the edge of the proposed

landfill cap. Sample locations included hi the risk assessment are identified hi Table 3-1.

3-2

3.2 CONTAMINANT SCREENING

Screening of contaminants and selection of chemicals of ecological concern included a number

of variables: observed maximum contaminant concentrations in the media of concern; frequency

of detection; mobility and persistence; toxicity (based on published effect levels); potential for

bioconcentration or bioaccumulation; background levels; and existing regulatory guidelines,

standards, or criteria. Hereafter, guidelines, standards, criteria, and effect levels are collectively

referred to as screening levels. Maximum sample concentrations were compared against

screening levels to determine whether on-site contaminant concentrations could potentially pose

a threat to the health of ecological resources.

Site background samples, collected by OBG (1993) in an adjacent but uncontaminated area, were

not used to screen analytical data for contaminants of concern. Site background data were not

utilized for three reasons. First, the background concentrations of many inorganics were the

highest detected, on-site or off-site. Second, background data were limited, particularly for

surface water. For soil, sediment, and surface water there were 2, 2, and 1 background

sample(s), respectively. Based on these factors, background data were not considered to be

representative of the non-site related concentrations in the areas surrounding the site. In

addition, ecological criteria, standards, guidelines, or effect levels were available to evaluate the

majority of the potential contaminants of concern without depending on such limited background

data.

Maximum contaminant levels hi surface sediments were compared to USEPA Region V

guidelines for the pollution classification of Great Lakes harbor sediments (USEPA, 1977),

sediment criteria issued by the New York State Department of Environmental Conservation

(NYSDEC, 1994), USEPA interim sediment quality criteria (USEPA, 1988), Guidelines for the

Protection and Management of Aquatic Sediment Quality Criteria in Ontario (Ontario Ministry

of Environment and Energy [OMEE], 1993), and low effect range levels (ER-Ls) and median

effect range levels (ER-Ms) from the National Oceanic and Atmospheric Administration (NOAA)

National Status and Trends Program (Long and Morgan, 1990).

3-3

The USEPA Region V sediment values are guidelines for the pollution classification of Great

Lakes harbor sediments (USEPA, 1977). The NYSDEC sediment criteria are considered

guideline values, as opposed to enforceable standards or department policy (NYSDEC, 1994).

NYSDEC sediment criteria for non-polar organic chemicals were developed using the

equilibrium partitioning approach while sediment criteria for metals are based on empirical data

from field and laboratory studies on the effects of metals hi sediments on benthic organisms.

The USEPA interim sediment quality criteria for non-polar organic chemicals were also

developed using the equilibrium partitioning approach. Where appropriate, screening levels for

organic compounds were adjusted for total organic carbon content as specified hi the USEPA

and NYSDEC criteria guidance documents.

Ontario Ministry of Environment and Energy sediment quality guidelines were developed for the

protection of aquatic environments (OMEE, 1993). OMEE sediment guidelines provide the

lowest effect level (LEL) and the severe effect level (SEL). The lowest effect level is defined

as "a level of contamination which has no effect on the majority of sediment-dwelling

organisms." Concentrations at the LEL indicate that a sediment is clean to marginally polluted.

A concentration at the SEL indicates "the sediment is considered heavily polluted and likely to

affect the health of sediment-dwelling organisms." During the contaminant screening process,

sample concentrations were compared against OMEE LEL values.

ER-Ls and ER-Ms provided by NOAA are based primarily on marine and estuarine sediment

concentrations although some freshwater sediments were included hi their derivation. Long and

Morgan (1990) identified the lower 10th percentile of concentrations hi the data as Effects

Range-Low (ER-L) and the median as Effects Range-Median (ER-M). ER-Ls and ER-Ms may

be used as general guidelines hi evaluating potential ecological effects from sediment

contaminants. Because a substantial proportion of the data used to derive ER-Ls and ER-Ms was

obtained from marine systems rather freshwater systems, only ER-Ms (the higher standards)

were used hi the screening process thus reducing the weight of these guidelines.

3-4

Contaminant concentrations in surface soils were compared to guidelines, standards, and criteria,

as well as U.S. national background levels for soil and other surficial materials [Shacklette et

al. (1971) as cited in Beyer (1990)]. Other literature sources used to evaluate soil contamination

included U.S. Fish and Wildlife chemical hazard reports and effect level studies.

Maximum contaminant concentrations hi surface water were compared to chronic and acute

water quality criteria. For the protection of aquatic life, USEPA and the Connecticut

Department of Environmental Protection (CDEP) have established freshwater Ambient Water

Quality Criteria (AWQC) for a number of chemicals hi surface water (USEPA, 1986; CDEP,

1992). However, federal and Connecticut AWQC have not yet been established for a large

number of contaminants, particularly for volatile and semi volatile compounds. Rhode Island has

established AWQC for a number of volatile and semivolatile compounds (RIDEM, 1988), and

these criteria are used, when available, for chemicals without existing USEPA or Connecticut

AWQC. Where appropriate, criteria for metals were adjusted for water hardness as specified

hi AWQC guidance.

The results of the contaminant screening process are presented by media hi the following

subsections (surface sediment, surface soil, and surface water). Chemicals that were selected

for further consideration (chemicals of concern or COCs) are summarized at the end of each

media discussion.

3.2.1 Sediment

Sediments constitute the organic and inorganic material that settle hi a water body over time.

For the purposes of the ecological risk assessment, substrate is considered sediment if it is

inundated by water on a fairly permanent basis. Sediment samples were collected from the

unnamed pond and brook by OBG (1993; 1994a). Under the condition of a presumptive remedy

(landfill cap, leachate collection system, and landfill gas collection system), leachate will no

longer flow and leachate seep sediments will dry. Therefore, the substrate within leachate seeps

was considered to be soil rather than sediment and consequently screened hi Section 3.2.2 - Soil.

3-5

Sediments were analyzed for volatile organic compounds, semi volatile organic compounds,

pesticides, polychlorinated biphenyls (PCBs), and inorganics. The analytical sediment data

collected from Phase 1A - Rounds 1 and 2 sediment are summarized in Table 3-2. Analytical

detection limits were higher than the lowest criteria value in one or more samples for PCBs,

pesticides, poly cyclic aromatic hydrocarbons (PAHs), antimony, mercury, silver, and cyanide.

Therefore, there may be more exceedances of criteria than can be delineated based on existing

data.

Four volatile organic compounds (acetone, ethylbenzene, tetrachloroethane, and xylene) were

detected in sediments (Table 3-2). Ethylbenzene, tetrachloroethane, and xylene were eliminated

from further consideration because they were each detected in only 1 of 24 samples. Acetone

was also determined not to be of concern due to a low maximum detected concentration (190

ppb) and because its toxicity to aquatic organisms is considered to be low (USEPA, 1985).

Eighteen semivolatile organic compounds were detected in sediment, including 14 PAHs, three

phthalates, and carbazole (Table 3-2). Twelve of the 14 PAHs had existing criteria values.

Benzo(a)pyrene, phenanthrene, and pyrene were selected as chemicals of concern because

concentrations exceeded screening levels at more than one sampling location. Screening levels

were not available for acenaphthylene and benzo(b)fluoranthene. Acenaphthylene was detected

at low concentrations (maximum = 170 ppb) and was therefore determined to not be of concern.

By contrast, the maximum concentration of benzo(b)fluoranthene was high (2100 ppb). Based

on high concentrations and frequency of detection (7 of 17 samples), benzo(b)fluoranthene was

selected as a chemical of concern.

No screening criteria were available for phthalates. However, phthalates were detected relatively

infrequently (2 of 17 samples, 3 of 17 samples, and 4 of 18 samples) and concentrations were

low (maximums of 79 to 300 ppb). Carbazole was detected in over one-third of sediment

samples (6 of 17 samples). Although screening levels were not available, carbazole was

eliminated from further consideration based on a low maximum concentration (78 ppb).

3-6

Of the twelve pesticides detected in sediment, screening levels were available for ten (Table 3

2). Concentrations of gamma-chlordane, DDE, DDT, endosulfan I, endosulfan n, and endrin

exceeded screening levels. Endosulfan I was determined not to be of concern because it

exceeded the screening level in only one sample. Although they did not have screening levels,

alpha-BHC and endrin ketone were screened out of the risk assessment based on a low frequency

of detection (2 of 23 and 1 of 23 samples, respectively). The PCB Aroclor-1254 was detected

in only 3 of 23 sediment samples. Although concentrations exceeded the OMEE LEL in two

samples, the maximum concentration of Aroclor 1254 was substantially lower than the screening

levels from four other sources. Based on this, Aroclor-1254 was eliminated from further

consideration.

Twenty-three inorganics were detected in sediments (Table 3-2). Concentrations of barium,

chromium, copper, iron, lead, manganese, nickel, and zinc exceeded screening levels in more

than one sample. Although a high percentage of barium is likely to be present in insoluble, non

toxic forms (USEPA, 1985), barium was retained as a chemical of ecological concern. Mercury

was detected in 5 of 24 samples, but concentrations exceeded screening limits in only one

sample. Therefore, mercury was not considered to pose a significant risk of harm at the site.

No screening levels were available for aluminum, beryllium, calcium, cobalt, magnesium,

potassium, sodium, thallium, and vanadium. Calcium, potassium, magnesium, and sodium were

screened out of the assessment because they are essential nutrients and naturally occur in high

concentrations. Thallium was screened out because it was detected in only 2 of 24 samples.

Average U.S. background concentrations in soil and other surficial materials [Shacklette et al.

(1971) as cited hi Beyer (1990)] were used as a reference to judge the significance of aluminum,

beryllium, cobalt, and vanadium hi sediment. These background data were used because no

ecological criteria were available and they provided the average and range of concentrations that

can be expected to occur naturally hi the United States. Although the background concentrations

were based primarily on soil samples, their application to sediment data was considered

appropriate for a conservative screening process.

3-7

The average concentrations of aluminum, beryllium, and vanadium were all less than the average

U.S. background concentrations. In contrast, the average sediment concentration of cobalt (11.7

mg/kg) slightly exceeded the U.S. background average concentration (10 mg/kg). Therefore,

cobalt was selected as a COC. Comparison of the concentrations of aluminum, beryllium,

vanadium, and cobalt to Massachusetts Department of Environmental Protection background soil

numbers yielded the same results and selection of cobalt as a COC (MADEP,1995).

In summary, chemicals of concern in sediment include benzo(a)pyrene, phenanthrene, pyrene,

benzo(b)fluoranthene, gamma-chlordane, DDE, DDT, endosulfanfl, endrin, barium, chromium,

cobalt, copper, iron, lead, manganese, nickel, and zinc.

3.2.2 Surface SoU

For the purposes of the ecological risk assessment, soil is defined as substrate that is directly

accessible by terrestrial or semi-aquatic receptors (i.e., not covered by water for any significant

length of time). Soil samples, grouped under the heading of "surface soil," included surface soil

samples, soil borings from 0 to 2 feet, and leachate seep sediments. Leachate seep sediments

were treated as soils because leachate will no longer flow and seep sediments will dry after the

installation of the landfill cap and leachate collection system.

Soils samples were collected by OBG (1993; 1994a) during Phase 1A -Rounds 1 and 2. Soils

were analyzed for volatile organic compounds, semivolatile organic compounds, pesticides,

PCBs, and inorganics (Table 3-3). Average U.S. background concentrations for soil and other

surficial materials [Shacklette et al. (1971) as cited hi Beyer (1990)] were used to screen

inorganics for which no ecological criteria existed.

Detected analytes hi surface soils were compared to guidelines and standards hi Beyer (1990)

and Fitchko (1989), as well as to effect levels found hi the literature. In the following text,

guidelines, criteria, standards and ecological effect levels are collectively referred to as screening

3-8

levels. In general, detection limits were lower than screening levels. However, detection limits

for a few PAHs (particularly benzo(a)pyrene), phthalates, and antimony exceeded criteria.

Six volatile organics were detected in surface soils (Table 3-3). Concentration of all volatiles

were below existing screening levels. Of the 23 semivolatile compounds detected in surface soil,

ecological screening levels were available for 16. Concentrations of four PAHs,

benzo(a)anthracene, benzo(a)pyrene, benzo(g,h,i)perylene and indeno(l,2,3-cd)pyrene exceeded

screening levels in one to six samples. These compounds were selected as chemicals of concern.

The concentrations of anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, bis(2

ethylhexyl)phthalate, chrysene, 1,4-dichlorobenzene, fluoranthene, naphthalene, phenanthrene

and pyrene were below screening levels. As a group, phthalates were infrequently detected and

only diethylphthalate exceeded screening levels (in one sample). Consequently, phthalates were

not considered to be of ecological concern.

Screening levels were not available for seven semivolatile compounds: acenaphthene,

acenaphthylene, bis(2-chloroethyl)ether, carbazole, dibenzofuran, fluorine, and

2-methylnaphthalene. Bis(2-chloroethyl)ether was screened out because it was detected in only

1 of 22 samples. With the exception of 2-methylnaphthalene, the remaining five compounds

were screened out of the risk assessment based on a relatively low frequency of occurrence (4

of 22 or 5 of 22 samples) and low concentrations (maximum concentrations ranged from 92 to

290 ppb, see Table 3-3). Detected at a maximum concentration of 2300 ppb,

2-methylnaphthalene was retained as a chemical of concern.

Ten pesticides (including two metabolites of DDT) were detected in surface soil samples (Table

3-3). All were eliminated as ecological chemicals of concern. Eight of ten compounds had

screening levels that were higher than the maximum observed soil concentration. Screening

levels were not available for aldrin and methoxychlor. However, because they were each

detected in only 2 of 21 samples, they were eliminated from further consideration. The PCB

Aroclor-1254 was detected hi only one sample and the concentration was an order of magnitude

below the screening level.

3-9

Twenty inorganics were detected in surface soil samples (Table 3-3). Screening levels or

background concentrations were available for all metals. Concentrations of arsenic, chromium,

cobalt, copper, lead, nickel, and silver exceeded ecological criteria. With the exceptions of

arsenic and cobalt, these metals were retained as chemicals of concern. Arsenic and cobalt were

determined not to be of concern because they exceeded respective screening levels in only one

sample each and average concentrations of each were less than one-fifth of the screening levels.

No screening levels were available for aluminum, calcium, iron, magnesium, potassium, and

sodium. Calcium, magnesium, potassium and sodium were screened out of the assessment

because they are essential nutrients and naturally occur in high concentrations. Aluminum was

screened out because the average concentration found on-site was lower than the average U.S.

background concentration [Shacklette et al. (1971) as cited in Beyer (1990)]. Iron concentrations

exceeded the average U.S. background concentration (25,000 mg/kg) in 6 of 22 soil samples.

Since iron may cause ecological toxicity in terrestrial habitats at very high levels (USEPA,

1985), iron was selected as a chemical of ecological concern in surface soil.

In summary, chemicals of ecological concern hi soil include benzo(a)anthracene, benzo(a)pyrene,

benzo(g,h,i)perylene, indeno(l,2,3-cd)pyrene, 2-methylnaphthalene, chromium, cobalt, copper,

lead, iron, nickel, and silver.

3.2.3 Surface Water

Relatively few organic compounds were present in surface waters at concentrations above

detection limits and most occurred at relatively low frequencies (Table 3-4). The detection

frequencies of inorganics were greater. There were numerous compounds for which detection

limits were higher than chronic AWQC in one or more samples. This is particularly a problem

for PCBs, pesticides, aluminum, mercury, and silver. Due to low hardness values at some

sampling locations, calculated AWQC were also below detection limits for cadmium, copper,

lead, and zinc. Thus, some potential exceedances of criteria values may be missed based on

existing data.

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Four volatile organic compounds were detected in surface water (Table 3-4). Methylene

chloride and toluene did not exceed screening levels. Although no screening levels were

available for acetone and 2-butanone, 2-butanone was eliminated from further consideration

based on frequency of detection (two of twenty-one samples). Acetone was eliminated because

its toxicity to aquatic organism is considered to be low (USEPA, 1985).

Five semivolatile organic compounds were detected (Table 3-4). Of those with screening levels,

only 2,4-dimethylphenol exceeded chronic AWQC. Based on frequency of detection (1 of 24

samples), 2-methylphenol was determined to be of no further concern. By contrast, 4

methylphenol was detected more frequently (5 of 24 samples) and its maximum concentration

was the highest of any semivolatile. Two semivolatile organics were selected as chemicals of

concern, 2,4-dimethylphenol and 4-methylphenol.

Methoxychlor, DDT and gamma-chlordane were detected in surface water. Each compound was

detected hi 1 of 24 samples. Consequently, pesticides were considered to not be of concern hi

surface water.

Of the 12 inorganics with screening levels, six exceeded chronic AWQC while three exceeded

acute criteria (Table 3-4). The metals that were detected hi excess of acute criteria (aluminum,

copper and zinc) were selected as contaminants of concern. Iron and lead exceeded chronic

criteria and were also contaminants of concern. Mercury exceeded chronic criteria as well, but

was determined not to be of concern since it was detected in only 2 of 25 samples.

No screening levels were available for barium, calcium, cobalt, magnesium, manganese,

potassium, sodium, and vanadium. Calcium, magnesium, potassium and sodium were not

considered of concern because they are nutrients and naturally occur at high concentrations.

Likewise, cobalt and vanadium were not considered to be important contaminants due to low

frequency of detection (3 of 25 and 1 of 25 samples). Barium and manganese, however, were

selected as chemicals of concern because they were detected hi 20 or more samples at significant

concentrations.

3-11

In summary, the chemicals of ecological concern for surface water at the site were

2,4-dimethylphenol, 4-methylphenol, aluminum, copper, iron, lead, manganese, barium, and

zinc.

3.2.4 Summary of the Contaminants of Ecological Concern

Soil, sediment, and surface water were determined to be media of concern via which ecological

resources may be exposed to contaminants. Ecological contaminants of concern are summarized

by media in Table 3-5. All of the volatile organic compounds detected at the site were

determined not to pose a risk of harm because individual compounds had low toxicity potential,

were detected infrequently, and/or were present hi concentrations that were lower than screening

levels.

3.3 POTENTIAL ECOLOGICAL RECEPTORS

Species groups most likely to receive potential exposure are those whose activities frequently

bring them into direct contact with surface sediments, wetland or upland surface soils, or surface

water; that directly consume plants growing on or hi these media; or that feed upon species

possessing one or both of these characteristics. These species groups are evaluated hi this

section to determine those potentially at risk of significant exposure. For those species or

species groups determined to be at risk of significant exposure, assessment and measurement

endpoints are outlined hi Section 3.4.

Selection of potential ecological receptors was based on wildlife observations made by M&E

biologists during a site walkover on 11 June 1993 and by OBG staff during the Remedial

Investigation (OBG, 1994a). M&E and OBG prepared tables listing wildlife observed directly

or by sign at the site (Appendix A). Based on 1994 correspondence with the US Fish and

Wildlife Service (USFWS), no federally protected species are known to inhabit the site (OBG,

1994a). Consequently, protected plants and animals were not considered hi selecting potential

indicator species for this assessment. Correspondence with the Connecticut Department of

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Environmental Protection dated January 22, 1996 confirms that there are no known extant

populations of federal or state protected species that occur at the site (Appendix B).

3.3.1 Benthic Invertebrates

Benthic organisms living hi the sediments of the unnamed brook are potentially at risk because

of their direct contact with contaminants hi this medium. Exposure could result from direct

contact with exposed outer membranes and respiratory surfaces, the direct ingestion of sediments

during feeding activities, and the consumption of contaminated prey or detritus, depending upon

the species' feeding habits. These organisms could also be directly exposed to contaminants in

surface water by the same pathways. The presence of pollution tolerant taxa in qualitative kick-

net surveys conducted in the unnamed brook (OBG, 1993) suggest that benthic invertebrate

community structure has been affected by site contaminants. Thus, benthic invertebrates are

considered a primary indicator species group to evaluate ecological risk hi aquatic areas.

3.3.2 Fish

No resident fish species are known to use the unnamed brook in the vicinity of the site and no

fish were observed hi this water body (OBG, 1993). Various fish species are known to use the

Farmington River. However, contaminant transport from the site is unlikely to reach the river,

due to a series of intervening wetland areas. Thus, exposure of fish to site contaminants is

unlikely and they are not considered to be potential ecological receptors.

3.3.3 Amphibians

As immature forms, adults, or both, salamanders, newts, toads, and frogs are potentially at risk

of exposure because of their close association with sediments, soils, and water. Most newts,

toads, and salamanders are terrestrial hibernators, whereas most species of frogs hibernate under

water hi mud (DeGraaf and Rudis, 1983). Thus, exposure to contaminants in sediments or soils

continues even during hibernation (although metabolism is greatly slowed), because of direct

3-13

absorption through their relatively unprotected membranous skin. These organisms conduct

considerable metabolite exchange directly through their skin (Schmidt-Nielsen, 1983).

Salamanders, newts, toads, and frogs consume earthworms, aquatic insects, and small fish or

tadpoles (DeGraaf and Rudis, 1983). These prey are among the most likely to contain elevated

levels of contaminants in their tissues. Amphibians may also ingest contaminated soil, sediment,

and detritus during feeding activities.

Frogs (including egg masses and tadpoles) were observed in the unnamed pond, and salamander

larvae were observed in the unnamed brook. Thus, frogs and salamanders will be used as

indicator species groups for the risk assessment.

3.3.4 Reptiles

Turtles and, to a lesser degree, snakes are potentially at risk of exposure based upon their life

history characteristics. Turtles are mostly aquatic and spend considerable time on the bottom

sediments of water bodies. Many snakes are sensitive to pollutants and have frequent contact

with water, soil, or sediment (Hall, 1980; DeGraaf and Rudis, 1983).

Turtles consume tadpoles, small fish, crustaceans, and some carrion (DeGraaf and Rudis, 1983).

Semiaquatic snakes also consume fish, frogs, aquatic insects, and salamanders, while more

terrestrial species may consume large numbers of soil invertebrates, especially earthworms

(DeGraaf and Rudis, 1983). These food items are likely to contain the highest levels of

contaminants of available food items present on the site. Reptiles may also ingest contaminated

soil, sediment or detritus during feeding activities.

No turtles were observed on the site and habitat appears to be marginal for most species.

Although snakes were observed on-site, lack of sufficient information on contaminant effects for

this taxa makes it difficult to use in a risk assessment. Thus, reptiles are not considered as

potential indicator species for use in the risk assessment.

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3.3.5 Mammals

Several mammalian primary consumers are potentially at risk of exposure to site contaminants.

These include, for wetland and aquatic areas, species such as beaver (Castor canadensis) and

muskrat (Ondatra zibethicus), and for upland areas, species such as woodchuck (Marmota

monax) and white-tailed deer (Odocoileus virginianus) and other small rodents (e.g., mice,

moles, and voles).

Beaver spend considerable time in potentially contaminated water and hi contact with potentially

contaminated sediments and wetland soils. Beavers carry sediments (mud) in their forefeet for

the purpose of lodge and dam building (Novak, 1987). The floors of the lodge are at least partly

composed of bare soils and/or sediments. Young animals would have considerable dermal

exposure to these soils/sediments before emerging from the lodge. Both adults and young would

be exposed to contaminants volatilizing from the soils or sediments into the confined airspace

of the lodge. This species may directly ingest contaminated soils or sediments hi the course of

dam or lodge construction, during grooming activities, and as they forage. Contaminants could

be absorbed directly through the skin (dermal exposure) and from the digestive tract after

ingestion. Exposure to contaminated water could also occur from these routes.

Beaver exposure via contaminated plant tissues is not likely to be significant because beavers

feed mainly on the bark of woody plants. Bark is not likely to concentrate contaminants to

levels that actively growing tissues may concentrate (e.g., roots and shoots). Muskrat are more

likely to be exposed to metals through the consumption of plant tissue than beaver since the

majority of the muskrat diet is roots and basal portions of aquatic plants (USEPA, 1993).

Likewise, exposure via plant ingestion is likely to be greater for woodchuck compared to beaver

because woodchuck primarily consume herbaceous vegetation (DeGraaf and Rudis, 1983).

Upland burrowing mammals, such as woodchuck and moles, could be at risk of exposure

through dermal contact with the soil or through the inhalation of semivolatile compounds. Soil

3-15

could also be directly ingested by these species during feeding and grooming activities. Species

such as white-tailed deer could be exposed to surface water contaminants in dietary water.

Mammalian secondary consumers with a possible risk of exposure include mink (Mustela visori)

and raccoon (Procyon lotor). Mink and, to a lesser degree, raccoon, preferentially feed upon

aquatic animals (e.g., fish, frogs, and tadpoles) and small mammals, depending upon relative

prey abundances (Linscombe et al., 1982; Kaufmann, 1982). These prey species are among the

organisms most likely to contain significant levels of contaminants in their tissues.

Since mink and raccoon have relatively large home ranges, the percentage of time spent on-site

and the percentage of food obtained on-site would influence the potential exposure. Raccoon

home ranges vary between 0.6 and 1.8 miles in diameter (400 to 1,200 acres), while mink home

ranges vary between 0.6 and 3.0 miles of river or up to 2,000 acres if the length of river is

considered the diameter of a circular home range (Linscombe et al., 1982; Kaufmann, 1982;

DeGraaf and Rudis, 1983; Eagle and Whitman, 1987).

All of the above species are known or likely to occur on-site or in downgradient areas. Based

on the above discussion, beaver and muskrat (primary consumers in aquatic areas downgradient

of the site), mink (predator; aquatic/wetland areas), woodchuck (primary consumer in upland

areas/burrows), and small rodents (primary consumer in upland areas/burrows) are proposed as

mammalian indicator species for use in the risk assessment.

3.3.6 Birds

Avian primary consumers are not likely to have significant exposure to site contaminants. Avian

secondary consumers at potential risk of exposure include species such as American robins

(Turdus migratorius). American robins consume earthworms and other upland soil biota

(DeGraaf and Rudis, 1983; Ehrlich et al., 1988). These prey species are among the most likely

upland fauna to contain contaminants in their tissues. Upland avian secondary consumers are

unlikely to be receive significant exposure along any other route. Since the unnamed pond and

3-16

brook adjacent to the landfill lack fish, wading birds (such as herons) are unlikely to forage in

these areas. Thus, American robins are selected as the avian indicator species hi upland areas

while no avian species are selected for aquatic/wetland areas.

3.3.7 Soil Invertebrates

Due to then: close association with surface soils and then- importance hi terrestrial food chains,

soil invertebrates are evaluated as part of the risk assessment. Since most of the available

information for this group of organisms consists of studies on earthworms, earthworms are used

as an indicator species hi the risk assessment.

3.3.8 Plants

Terrestrial, wetland, and aquatic plants rooted hi contaminated soils or sediments may uptake,

through their root surfaces, some of the contaminants present hi the pore water of these media

during water and nutrient uptake. A secondary exposure route, absorption through leaf surfaces

of gaseous contaminants or contaminants deposited on these surfaces by ah- or water, is not

likely to be important at the site due to the lack of exposed contaminated soils and low

deposition rates. Unrooted, floating aquatic plants, such as duckweed (Lemna spp.), and other

emergent and submergent aquatic plants may uptake contaminants directly from surface water.

Plants are discussed in this risk assessment as a potential contaminant source. Plants may take

up some contaminants from soil, sediment, and/or water, and transfer them to herbivores. This

pathway also includes the consumption of detritus, particularly by benthic and terrestrial

invertebrates. Many invertebrate species feed on detritus and could therefore become a source

of contaminant exposure for secondary consumers.

3-17

3.4 ASSESSMENT AND MEASUREMENT ENDPOINTS

To evaluate whether risks to ecological resources exist at a site, an assessment endpoint must

be selected. The assessment endpoint defines the nature of site risk. USEPA (1992) defined

assessment endpoint as an explicit expression of the environmental value that is to be protected.

The presence of a reproductively viable community of species was selected as the assessment

endpoint at the Barkhamsted site. If site contaminants are negatively affecting ecological

resources, it would be expected that the natural community would be less diverse, of a different

composition, or less abundant than at an uncontaminated site of similar character.

Many taxa are expected to inhabit the site. A representative subset of organisms was selected

to represent this community of species. The subset includes benthic invertebrates, earthworms,

green frog, spotted salamander, American robin, deer mouse, woodchuck, muskrat, mink, and

beaver. These organisms represent a significant fraction of the guilds, trophic levels, and

general life histories that are expected to occur at the site. The term "reproductively viable"

was added to the assessment endpoint to indicate that, for each species, a minimum number of

individuals must be present and reproductively viable for the species to be continually

represented at the site.

Measurement endpoints illustrate the performance of the assessment endpoint. USEPA (1992)

defined measurement endpoint as a measurable ecological characteristic that is related to the

valued characteristic chosen as the assessment endpoint. Each assessment endpoint must have

at least one measurement endpoint. The measurement endpoint at the Barkhamsted site is the

comparison of a site-specific Hazard Quotient (HQ - calculated by dividing the estimated

exposure by the reference dose that is known to cause an adverse effect on a receptor) to a

reference HQ (i.e., HQ = 1 and HQ=10). Contaminant specific HQs were calculated for each

of the species representing the Barkhamsted community. When calculated HQs are high, site

contaminants may be harmful enough to preclude, through death or reproductive impairment,

the presence of a reproductively viable community (the assessment endpoint).

3-18

In addition to calculating HQs for each contaminant, cumulative impacts for classes of chemicals

(e.g., metals) were evaluated for each exposure pathway attributable to an indicator species.

HQs for each chemical class were summed to obtain Hazard Indices (HI). If the HI for a

specific pathway was high, it was presumed uiat the particular species, and others within the

same guild, were being negatively affected (i.e., the assessment endpoint is degraded).

3-19

SECTION 4.0

EXPOSURE ASSESSMENT

The objective of the exposure assessment is to evaluate the status of soil, sediment, and surface

water as potential exposure sources for ecological receptors. Meeting this objective requires

integration of information on the fate and transport of chemicals of concern and the life histories

of potential ecological receptors inhabiting the site.

4.1 SOURCE CHARACTERIZATION AND SELECTION OF EXPOSURE PATHWAYS

Potential exposure to contaminant sources will be reduced with the installation of the landfill

cap. All seeps, sediments, and soil located on the landfill will be covered. Potential threats

from contaminants in the sedimentation basins will also be removed because these areas will be

regraded. The installation of an infiltration barrier such as a bentonite clay/polyethylene

composite liner will lower the level of groundwater under the landfill, and will eliminate seepage

outside of the cap. Therefore, those seeps located outside the cap, and not covered, will cease

to receive water and will dry up. Since contaminated groundwater will no longer be emanating

from the landfill, surface water in discharge areas such as the wetlands or streams may receive

less contamination. However, potential exposure to contaminants via surface water and

sediments were evaluated to determine the current status of this media as a potential exposure

source.

Soil, sediments and surface water remain as media of ecological concern. In addition to all

uncovered soils, the sediments hi the seeps outside of the cap are treated as terrestrial soils,

since they will be dry. The sediments and surface waters of concern are located hi the unnamed

brook, hi the beaver ponds along the unnamed brook east of U.S. Route 44, and hi the unnamed

pond located north of the unnamed brook (Figure 1-2). Since the capping of the landfill will

presumably not affect the hydrology of these areas, substrate that is currently considered

sediment will be evaluated as such. The text that follows is a discussion of potential exposure

pathways of indicator plant and animals species to the media of concern (Table 4-1).

4-1

4.1.1 Plants

Terrestrial, wetland, and aquatic plants rooted in contaminated soils or sediments may uptake,

through their roots surfaces, some of the contaminants present in the pore water of these media

during water and nutrient uptake. Free floating plants such as duckweed may uptake

contaminants directly from the surface water. A secondary exposure route, absorption through

leaf surfaces of gaseous contaminants or contaminants deposited on these surfaces by air, water

or dust, is not likely to be important at the site due to the lack of exposed contaminated soils and

low deposition rates. Plants are discussed in this assessment only as a potential medium,

uptaking contaminants from soil, sediment, leachate, and/or water, and transferring them to

herbivorous animals who consume their tissues or to invertebrates that consume detritus and

become a potential exposure source for secondary consumers.

4.1.2 Animals

There are four major ways fauna might be exposed to contaminants: (1) direct ingestion of

contaminated abiotic media, (2) the consumption of contaminated animal or plant tissues

(includes detritus), (3) direct inhalation, and (4) absorption through skin or gill surfaces.

Direct Ingestion of Contaminated Abiotic Media. Media of potential concern are surface soil,

surface water and sediment. Direct ingestion of contaminated soil or sediment could occur while

animals grub for food, feed on plant matter covered with contaminated soil, filter feed in areas

where sediments have been resuspended in the water column, or preen or groom themselves.

In addition, aquatic deposit feeders and earthworms directly ingest large quantities of bulk

sediment or soil in order to obtain the energy-rich fraction; these organisms would likely have

a significant exposure from this pathway. Surface water may also be directly ingested by

organisms while obtaining dietary water or feeding.

Ingestion of Contaminated Tissues. It is possible that terrestrial, wetland, and aquatic plants

rooted in contaminated soils or sediments could uptake contaminants from these media and

4-2

incorporate these compounds into their tissues, thereby presenting a possible risk to animals

(primary consumers) feeding upon those plants (e.g., woodchuck and muskrat). Many

invertebrates may be exposed to contaminants through the consumption of detritus. Predatory

organisms (secondary consumers) may be at risk when feeding upon prey containing elevated

levels of contaminants in their tissues. The risk of exposure to predators would depend upon

the concentration of contaminants in the particular tissues consumed and the rate of food

consumption. The dose received would also depend upon the rate of assimilation of the

contaminants (or toxic metabolites resulting from chemical changes in the compounds) from the

digestive tract during digestion and the rate of metabolism.

Various common food species (e.g., earthworms) for upper-level consumers in terrestrial

environments are known to bioaccumulate some inorganic and organic compounds to levels

above those found in the environment. Although no site-specific data on tissue concentrations

of contaminants exist for earthworms, these organisms have been shown to bioaccumulate certain

metals, such as copper and lead, from surface soils (Roberts and Dorough 1985; Bysshe 1988)

and pesticides such as DDT. Thus, prey organisms may pose a potential exposure risk to

predators that consume them.

Inhalation Exposure. To some extent, semivolatile compounds tend to volatilize from surface

soils or surface water. In vapor form, these compounds may become bioavailable to organisms

during respiration, which becomes an important exposure route. The lungs, with their large

surface area for gas exchange, readily absorb many chemicals and pass them directly into the

bloodstream. Most hazards from volatile organic compounds are associated with inhalation

exposure (USEPA, 1985); for metals and semivolatile compounds with higher molecular weights

(e.g., benzo(a)pyrene), there is a reduced exposure risk from inhalation because these

compounds tend to remain adhered to surface particles. However, these particles may be inhaled

as dust, depending upon conditions at the site. Since the landfill will be capped and on-site

vegetation keeps soil intact and reduces erosion, exposure via the inhalation of dust is not likely

to be an important exposure pathway.

4-3

Exposure via inhalation exposure could be important for animals such as muskrats, beavers, and

woodchucks that spend a considerable amount of time in a confined space. For example,

semivolatile contaminants present in the soil could volatilize into the confined airspace of the

woodchuck burrow, where they could reach relatively high concentrations. This exposure risk

would be most severe for postnatal animals as they would have continuous exposure during the

early period of their life, prior to their exit from the burrows. The risk would also be severe

since the animals would be most susceptible to the effects of the contaminants because of the

high rate of growth experienced at this life stage. Exposure of the pregnant female to

contaminants in the burrow air may also have effects at the fetal stage, resulting hi fetal death,

birth defects, or reduced birth weight.

Since volatile organic compounds are not present hi on-site surface soils at levels considered to

be of concern to ecological systems, and the concentrations of the few semivolatile compounds

in the areas with suitable soils (based upon soil type and soil depth) for most burrowing animals

(e.g., woodchuck) were relatively low, inhalation is not likely to be an important exposure

pathway. The ultimate fate of PAHs hi sediment is chemical oxidation, biotransformation, or

biodegradation by bacteria and other benthic organisms (Eisler, 1987).

Dermal Exposure. Direct exposure to contaminated surface soils or surface sediments is

another exposure pathway important to some species. Exposure could result from direct dermal

contact with the soils or sediments on unprotected surfaces [e.g., gill membranes (from

suspended sediments) or exposed skin].

Dermal exposure may be an exposure pathway for semi-aquatic animals such as muskrat, mink,

and beaver that spend a considerable amount of time hi water. Dermal exposure is also likely

important to burrowing mammals (such as woodchucks), amphibians and reptiles that hibernate

hi the sediments (such as frogs and turtles), and benthic invertebrates. These taxa all have

extensive contact with surface water, sediments and/or surface soils during all or part of their

lives.

4-4

4.2 FATE AND TRANSPORT ANALYSIS

This section summarizes the pertinent information concerning the fate and transport of the

ecological chemicals of concern (Table 3-5) applied to ecological receptors. The chemicals of

concern for the ecological risk assessment are pesticides, PAHs and inorganic analytes in

sediment, PAHs and inorganic analytes in soil, and phenols and inorganic analytes in surface

water.

Fate and transport in the environment depends on the properties of both the contaminant and the

environmental medium in which it occurs. For each chemical type, the physical and biological

pathways are identified, as are the storage and degradation mechanisms present in the

environment.

4.2.1 PAHs

PAHs are virtually ubiquitous in the environment, originating from anthropogenic sources as

well as forest fires, microbial synthesis, and volcanic activity. They have been detected in

animal and plant tissues, sediments, air, surface water, drinking water and groundwater (Eisler,

1987). Anthropogenic sources of PAHs in the environment include combustion processes used

in the steel industry, heating and power generation, and petroleum refining.

The primary fate of PAHs in die environment is adsorption onto particulates, especially in media

high in organic content, which tends to reduce their bioavailability. Higher molecular weight

PAHs are relatively immobile because of the large molecular volumes and their low volatility

and solubility. Most PAHs can be metabolized by higher organisms and therefore tend not to

be bioaccumulated over long time periods.

PAHs in water may volatilize, disperse into the water column, become incorporated into bottom

sediments, concentrate in aquatic biota, or experience chemical oxidation and biodegradation

(Eisler, 1987). The chemical properties of PAHs suggest that the most likely fate is adsorption

4-5

onto suspended paniculate matter, especially particulates high in organic content. PAHs in

aquatic sediments generally degrade slowly and may persist indefinitely due to the absence of

penetrating radiation and oxygen. The ultimate fate of PAHs in sediments is chemical oxidation,

biotransformation or biodegradation by bacteria and other benthic organisms (Eisler, 1987).

PAHs hi surface soils will likely be volatilized into the atmosphere. PAHs in subsurface soils

may be assimilated by plants, degraded by soil microorganisms, or accumulated to relatively

high levels hi the soil. High PAH concentrations in the soil can lead to high microorganism

populations capable of degrading the compounds (Eisler, 1987)

Biodegradation and biotransformation by benthic organisms, including microbes and

invertebrates, are the most important biological fate processes for PAHs in sediments. Most

animals and microorganisms (shellfish and algae are notable exceptions) can metabolize and

transform PAHs to breakdown products that may ultimately experience complete degradation

(Eisler, 1987). PAHs of high molecular weights degrade slowly (half-lives of up to a few years)

by microbes and readily by multicellular organisms (USEPA, 1979). Biodegradation probably

occurs more slowly hi aquatic systems (especially anaerobic systems) than hi soil (USEPA,

1985).

Some PAHs rapidly bioaccumulate in animals because of the their high lipid solubility (Eisler,

1987). The rate of bioaccumulation is inversely related to the rate of PAH metabolism and is

also influenced by the concentration of PAH to which the organism is exposed. Both rates are

dependent on the size of the specific PAH molecule; PAHs with less than four rings are readily

metabolized and not bioaccumulated, while PAHs with more than four rings are more slowly

metabolized and tend to bioaccumulate on a short-term basis (USEPA, 1979; USEPA 1985;

Eisler, 1987).

4-6

4.2.2 Metals

Assessing the mobility and persistence of metals in environmental media is complicated and often

difficult because of the many inorganic and organic complexes and salts they form. In addition,

metals undergo a variety of processes in soils and water, which include hydrolysis, reduction,

oxidation, and ion exchange. These reactions are highly dependent on factors such as pH,

salinity, ionic strength, particle-surface reactions, and the presence of anions and natural organic

acids (humics and fulvics). Many of the metals of concern at this site are relatively insoluble

either in metallic form or as inorganic complexes and salts yet become soluble in the presence

of organic acids and oxidizing conditions. Cation exchange of metals by soils and sediments is

the dominant fate mechanism in natural systems.

Aluminum is one of the most abundant elements in the earth crust and occurs in nature primarily

as aluminum silicates and aluminum oxide. The direct toxic potential of aluminum is low

compared to that of many other metals. Mammals and birds can effectively limit the absorption

of aluminum and excrete any excess (Scheuhammer, 1987). Scheuhammer (1987) as well as

USEPA (1985) have shown that the direct toxicity of aluminum to some animal species is

relatively low.

Aluminum is not known to biomagnify hi terrestrial or aquatic food chains (Wren et al., 1983)

in large part because it is toxic to plants. Soil-to-plant bioconcentration factors (BCFs) are low,

ranging from 0.00065 to 0.004 (Bysshe, 1988) indicating a low probability of significant plant

uptake from soil.

Barium readily forms insoluble carbonate and sulfate salts which have low toxicity (USEPA,

1985). In contrast, soluble barium salts are toxic. Bioaccumulation is not an important fate

process for barium, but it is an important trace element for plants. Estimated soil-to-plant BCFs

are 0.015 to 0.15 (Bysshe, 1988).

4-7

Chromium is a heavy metal that is most frequently found in a trivalent or hexavalent oxidation

state. Chromium (VI) is readily converted to chromium (HI) in the presence of reducing agents

(USEPA, 1985). Chromium (HI) adsorbs to soil/sediment and organic paniculate matter and

therefore is generally less mobile than chromium (VI).

Chromium is an essential nutrient that often accumulates in aquatic organisms at concentrations

higher than ambient water concentrations, but lower than sediment concentrations. Chromium

accumulates in semi-aquatic and terrestrial organisms as well (Eisler, 1986). Chromium may

also be transferred through trophic levels (USEPA, 1985). Although the genus does not occur

at the Barkhamsted site, Giblin et al. (1980) showed that chromium accumulates in marsh grass

(Spartina spp.). Estimated soil-to-plant BCFs range from 0.0045 to 0.0075 (Bysshe, 1988).

In biological materials, chromium is usually present in the trivalent form (Eisler, 1986).

According to Eisler (1986), chromium (VI) is generally more toxic to freshwater species than

chromium (III). Chronic exposure to chromium (VI) has been demonstrated to reduce growth

rates hi freshwater algae and duckweed and to affect the survival and growth of cladocerans

(USEPA, 1985). Some salts of chromium are carcinogenic and chromium (VI) is a teratogen

in hamsters. The toxicity of chromium (III) to mammals is lower than the toxicity of chromium

(VI) (Eisler, 1986).

Cobalt is an essential element that can be accumulated by plants and animals although it is not

thought to accumulate to excessive concentrations (USEPA, 1985). Estimated soil-to-plant BCFs

range from 0.007 to 0.02 (Bysshe, 1988). Soluble cobalt is found in low concentrations in

aquatic ecosystems. Mobility is limited because cobalt adsorbs to clay minerals and hydrous

oxides of iron, manganese, and aluminum in the clay fractions of sediments and soils (USEPA,

1985). Chelation of cobalt with organic compounds also occurs. Information regarding the

toxicity of cobalt to wildlife is limited.

Copper, an essential element, is accumulated by plants and animals, although it is not generally

biomagnified (USEPA, 1985). Plants may take up copper from soils and translocate it from

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roots to edible portions of the plant. Estimated soil-to-plant BCFs range from 0.25 to 0.40

(Bysshe, 1988). Bysshe (1988) determined that concentrations of copper hi soils will generally

kill plants before they can accumulate tissue concentrations that are toxic to grazing animals.

Earthworms bioconcentrate copper and can be negatively affected via a decrease hi survival,

growth and reproduction rates (Beyer, 1990; M&E, 1992). Bioconcentration factors vary with

soil concentration (Beyer, 1990). The bioavailability of copper hi earthworm tissues to predators

is unknown.

Iron is an essential element required by both plants and animals. Ferrous, or bivalent (Fe++),

and ferric, or trivalent (Fe+++) iron are the primary forms of concern hi aquatic environments.

The ferrous form can persist hi anaerobic waters. Iron can persist hi natural organometallic,

humic compounds, or hi colloidal forms. Black or brown swamp waters may contain iron

concentrations of several mg/1 hi the presence or absence of dissolved oxygen, but this form of

iron has little effect on aquatic life (USEPA, 1985). The ingestion of excessive amounts of iron

can produce toxic effects hi mammals (USEPA, 1985). Therefore, iron is not likely to cause

toxicity hi animals unless it is present at high levels. Iron is not known to biomagnify within

food chains (Wren et al., 1983), and estimated soil to plant BCFs are low (0.001 to 0.004)

(Bysshe, 1988).

Lead is a non-essential element that is largely immobile hi soils (Bysshe, 1988). There is little

translocation from plant roots to edible parts and soil-to-plant BCFs are estimated at 0.009 to

0.045 (Bysshe, 1988). Adverse effects to terrestrial plants have been reported (Bysshe, 1988;

Eisler, 1988). Earthworms may bioconcentrate lead (Beyer, 1990; Roberts and Dorough, 1985)

and lead may be toxic at high concentrations, affecting both survival and reproductive rate.

Ducks and raptors have been poisoned by ingestion of lead shot. For example, the American

black duck (Anas rubripes) showed weight loss, emaciation, or were killed by a single oral lead

dose of 254 mg (Eisler, 1988). However, Eisler (1988) indicated that adverse effects due to

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other exposure or dietary routes, such as the consumption of plant and animal tissues, are less

likely to occur. Food chain magnification of lead is negligible (Eisler, 1988).

In most natural aquatic systems, manganese is expected to be present predominantly in the

suspended particulates and sediments as MnO2 or Mn304 or both. The soluble chelated

manganese in aquatic systems is likely to be less soluble than free manganese ions. Thus,

although manganese may undergo speciation through chemical and microbial reactions hi

systems, it may persist for a long period.

Evidence suggests that significant bioaccumulation of manganese may not occur in organisms

at higher trophic levels (USEPA, 1985). Manganese may, however, be bioaccumulated at lower

trophic levels, but biomagnification hi food chains is not likely to be significant (Wren et al.,

1983). Plants may uptake manganese from soils and translocate it to edible portions of the plant.

Soil-to-plant conversion factors range from 0.05 to 0.25 (Bysshe, 1988). Levels of manganese

in soils will generally kill plants before plants can accumulate levels that are toxic to most

grazing animals.

Nickel is a non-essential element that is usually present in nature within mobile and highly

soluble compounds. In organic-rich and polluted waters, sorption of nickel to other chemicals

is less likely and incorporation into sediment becomes an important fate process (USEPA, 1985).

Nickel is not significantly accumulated by aquatic organisms (USEPA, 1985). Bysshe (1988)

estimated a soil-to-plant BCF of 0.06 for nickel.

Silver is a non-essential metal that exists in variety of chemical forms in aqueous systems.

Reducing conditions of sediment, formation of insoluble silver sulfides and metallic silver may

reduce the concentration of soluble silver in the water column (USEPA, 1985). Although silver

is readily bioaccumulated by aquatic plants, invertebrates, and vertebrates, there is little

magnification of silver through the food chain (USEPA, 1985). Estimated soil-to-plant BCFs

range from 0.1 to 0.4 (Bysshe, 1988).

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Zinc is an essential element. In nature, the most common form of zinc is the +2 valence state.

Sorption of the divalent cation by hydrous iron and manganese oxides, clay minerals, and

organic material removes zinc from the water column. In reducing environments, precipitation

of zinc sulfide also limits zinc mobility. Zinc is bioaccumulated because it is an essential

nutrient (USEPA, 1985). Soil-to-plant BCFs estimated by Bysshe (1988) range from 0.9 to

15.0.

4.2.3 Pesticides

Five pesticides (DDE, DDT, endosulfan II, endrin, and gamma-chlordane) were identified to be

of concern hi the sediments hi the beaver ponds. Although several pesticides were present hi

soils surrounding the landfill (Table 3-3), concentrations were below the screening criteria and

thus were not considered to be of concern.

DDE is a breakdown product of DDT. These chlorinated hydrocarbons were used extensively

as pesticides hi the United States. Bioaccumulation of DDT and its breakdown products has

been documented hi a variety of species. Bioaccumulation occurs via direct absorption by

aquatic organisms through contaminated water. The concentrations of DDT, DDE, and ODD

biomagnify hi the food chain via transfer of residues through sequential feeding by predators

(USEPA, 1990).

The DDT series of pesticides is acutely toxic to aquatic invertebrates and birds, but information

on damage to aquatic plants is limited. However, DDT and DDE have been found to reduce

the level of photosynthesis hi freshwater algae.

While there is variation, sublethal effects to mammals attributable to DDT include teratogenic,

mutagenic, and carcinogenic damage. Birds may also be affected by the DDT series of

pesticides through a decrease hi reproductive rate, hatchling survivability, shell thickness, and

fecundity, as well as through an increase hi embryo death rate (USEPA, 1993).

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The chlorinated hydrocarbon endrin is also a very persistent insecticide. Like DDT and its

metabolites, endrin is very toxic to aquatic organisms and is known to bioaccumulate in the food

chain, particularly in benthic organisms as a result of the direct ingestion of contaminated

sediments (Nimmo, 1985). Endrin is acutely toxic to terrestrial wildlife as well, and has been

utilized as both a rodenticide and avicide. The compound is not a carcinogen, but has been

shown to be a potent teratogen and reproductive toxin (USEPA, 1985).

Chlordane was also formerly used as a pesticide in the United States. It is very persistent in the

environment and strongly bioaccumulates in aquatic and terrestrial organisms. Chlordane

persists in aquatic environments to a greater degree when organic material is present hi surface

water (USEPA, 1985). Chlordane may sorb to sediment or bind to soil particles for years after

surface application.

Chlordane is very toxic, particularly for aquatic organisms. Although biotransformation may

be an important fate of chlordane, it is likely a slow process. Chlordane appears not to

concentrate extensively in the higher members of the food chain (USEPA, 1985).

Endosulfan is a pesticide that exists hi alpha (endosulfan I) and beta (endosulfan II) forms.

Along with the other pesticides described above, it is toxic to animals other than insects.

Endosulfan has been found to affect the nervous system of mammals as well as organs and

immune system at low level chronic doses (M&E, 1992). Reproduction hi animals may also be

affected by endosulfan.

4.2.4 Phenolics

Two phenolic compounds were determined to be contaminants of concern hi surface water, 2,4

dimethylphenol and 4-methylphenol. Due to high water solubilities, phenolics will leach from

soils into groundwater or surface water (M&E, 1994). Volatilization from soils and water is

minimal because of low vapor pressure and low Henry's Law Constant. Phenolics biodegrade

quickly in soil and water systems under both aerobic and anaerobic conditions to form simple

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aliphatic alcohol and carboxylic compounds. Degradation of 2,4-dimethylphenol may occur

throughphotooxidation, metal-catalyzed oxidation, sorption, andbiodegradation(USEPA, 1985).

In unaerated water, absorption onto organic materials may also be a fate of 2,4-dimethylphenol.

4.3 EXPOSURE SCENARIOS AND INTEGRATED EXPOSURE ANALYSIS

Eight species and one taxa (benthic invertebrates) were selected as indicators (Table 4-1) to

evaluate the effect of contamination at the site. In this section, information on existing site

conditions, coupled with additional information on the life histories of biota utilizing the study

area are integrated to determine the most probable scenarios for contaminant exposure.

Exposure scenarios are outlined for each indicator species/taxa group.

4.3.1 Benthic Invertebrates

Benthic invertebrates may be exposed to site contaminants via sediment or surface water.

Chemicals of concern hi sediments included PAHs, pesticides and metals. Metals and phenolics

were identified as of concern in surface water. The most likely exposure scenario involves three

pathways that apply to both sediment and surface water: dermal contact, absorption through

respiratory surfaces (e.g., gills), and ingestion of contaminated abiotic media, detritus, or plant

and animal tissue.

4.3.2 Earthworm

The exposure scenario for earthworms (potentially several species) entails the consumption of

metals and PAHs as they burrow through soil. Neuhauser et al. (1985) and Thompson (1971),

among others, have documented the toxicity of organic compounds on the survival of

earthworms. Likewise, there is a wealth of literature on the bioaccumulation of heavy metals

in earthworms (Diercxsens et al., 1985; Gish and Christensen, 1973; Helmke et al., 1979;

Morgan and Morgan, 1988a; Morgan and Morgan, 1988b). Toxicity and bioaccumulation data

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from the literature in combination with on-site soil concentrations will enable a determination

of the level of risk to earthworms.

4.3.3 Green Frog

Frogs (including egg masses and tadpoles) were observed in the unnamed pond during the June

1993 M&E site visit. The green frog (Rana clamitans melanota) likely inhabits the site. This

species may be exposed to contaminants hi surface water and sediment through dermal contact,

absorption through respiratory surfaces, and ingestion of contaminated abiotic media or detritus.

The green frog may also be exposed to contaminants in soil through dermal contact or direct

ingestion. Another exposure scenario involves the consumption of plants (larval stage) and

invertebrates (adult stage) that contain contaminants hi their tissues. Contaminants of concern

for the green frog include metals, pesticides, PAHs and phenolics, since frogs are potentially

exposed through pathways that include water, soil, and sediment.

4.3.4 Spotted Salamander

Salamander larvae were observed in the unnamed brook during the June 1993 M&E site visit.

According to habitat preference and distribution information hi DeGraaf and Rudis (1983), the

spotted salamander (Ambystoma maculatum) likely inhabits the site. As for the green frog, there

are two scenarios for exposure of the spotted salamander to site contaminants. First, the spotted

salamander may be exposed to contaminants hi soil, surface water, and sediment through dermal

contact, absorption through respiratory surfaces, and ingestion of contaminated abiotic media or

detritus. Hibernation within soil may be an important exposure point for the spotted salamander.

The second exposure scenario involves the consumption of primarily invertebrate prey that

contain contaminants hi their tissues. Contaminants of concern for the spotted salamander

include metals, pesticides, PAHs and phenolics.

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4.3.5 American Robin

The exposure scenario for the American robin (Turdus migratorius) involves the consumption

of earthworms that have accumulated contaminants hi body tissue and also the incidental

consumption of soil. Contaminants of concern for American robins include PAHs and metals,

since these were identified as contaminants of concern.

4.3.6 Deer Mouse

The deer mouse (Peromyscus maniculatus) is a common inhabitant of open areas and is therefore

likely to inhabit the site. The deer mouse may be exposed to contaminants through dermal

contact with soil or direct ingestion of soil. Nests are constructed just below ground in a

burrow, under rocks, or in debris.

The deer mouse rarely drinks free water in nature (Jones and Birney, 1988) and would not likely

contact sediments. Consumption of food items (primarily seeds and invertebrates) that contain

tissue contaminants is a second exposure pathway. Deer mice are unlikely to consume

significant quantities of contaminants hi vegetative forage. Chemicals of concern for deer mice

include metals and PAHs, since these were identified as COCs in soil.

4.3.7 Woodchuck

Woodchucks (Marmota monax) are typical inhabitants of forest edges and open habitat. OBG

biologists observed a woodchuck burrow on-site during the Phase 1A site characterization (OBG,

1993). Woodchucks burrow hi the ground and are herbivorous. They may be exposed to si