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YEOMAN CREEK/EDWARDS FIELD LANDFILLS

STOCHASTIC RISK ASSESSMENT

VOLUME I OF IITEXT, TABLES, & FIGURES

ICF KAISER

ICF KAISERENVIRONMENT & ENERGY GROUP

ICF Kaiser tneineers. inc.K.S. Crump Division1201 C-aines StreetRuston. L\ 71270-3107U8/2jj-4BOO Fax 318/255-4960

March- 16, 1994

Mr. Richard Boice, P.E.U.S. Environmental Protection Agency77 West Jackson BoulevardMail Code HSRL-6JChicago, Illinois 60604

Mr. Stephen NussbaumIllinois Environmental Protection Agency2200 Churchill RoadSpringfield, Illinois 62794-9276

Re: BASELINE RISK ASSESSMENTYEOMAN CREEK/EDWARDS FIELD LANDFILLS RI/FS

Dear Messrs. Boice and Nussbaum:

It has come to my attention that the Final Baseline Risk Assessment for YeomanCreek/Edwards Field Landfills sent to you on March 7, 1994, inadvertentlycontained the designation "draft" in the footer. This was an oversight on mypart since the documents sent you, both the Baseline Risk Assessment and theStochastic Risk Assessment, are indeed final. I am enclosing two copies ofeach document with the correct designation for your records. These documentsdiffer only in the footer for each page, which has been corrected from "Draft- March, 1994" to "Final - March, 1994." No other changes to these documentshave been made.

I certainly apologize for the oversight. If you need additional copies foryour records, please call me at 318-255-4800.

Sincerely,

ICF KAISER ENGINEERS, INC.

Annette M. Shipp, Ph.D.

AMS/lmw

FINAL

YEOMAN CREEK/EDWARDS FIELD LANDFILLS

STOCHASTIC RISK ASSESSMENT

VOLUME I OF IITEXT, TABLES & FIGURES

Submitted to:

Yeoman Creek PRP Committee

DISTRIBUTION:

1 copy - William Beck, Esq., Lathrop & Norquist1 copy - Shell J. Bleiweiss, Esq., McDermott, Will & Emery1 copy - Thea Dunmire, Dickenson, Wright, Moon, Van Dusen, Freeman1 copy - Larry Keller, Outboard Marine Corporation1 copy - Jeff Diver, The Jeff Diver Group1 copy - Richard Parson, P.E., City of Waukegan1 copy - Pierre Talbert, Esq., Foley & Lardner1 copy - Derrick Vallance, Browning-Ferns Industries of Illinois, Inc.1 copy - Dale Vitae, Outboard Marine Corporation1 copy - Colder Associates, Inc.

Yeoman Creek/Edwards Field Landfills - Stochastic

TABLE OF CONTENTS

1.0 PUBLIC HEALTH EVALUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1.1 Purpose and Scone of Stochastic Baseline Risk Assessment . . . . 21.1.2 Site Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.1.3 Site Investigations and Data Sources . . . . . . . . . . . . . . . . . . . 41.1.4 Stochastic Risk Assessment Methodology . . . . . . . ' . . . . . . . . 51.1.5 Report Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.2 Problem Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.2.1 Identification of COPCs . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.2.1.1 Background Screening . . . . . . . . . . . . . . . . . 81.2.1.2 Comparison to ARARs . . . . . . . . . . . . . . . . . 111.2.1.3 Preliminary Risk Based Screening . . . . . . . . . . 131.2.1.4 CQPCs . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.2.2 Identification of Receptors and Exposure Pathways of PotentialConcern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.2.2.1 Surface Soil Pathway . . . . . . . . . . . . . . . . . . 211.2.2.2 Surface Water Pathway . . . . . . . . . . . . . . . . . 221.2.2.3 Surface Water Sediment Pathway . . . . . . . . . . 231.2.2.4 Soil Gas Pathway . . . . . . . . . . . . . . . . . . . . 231.2.2.5 Groundwater Pathway . . . . . . . . . . . . . . . . . 241.2.2.6 Leachate Seep Soil Pathway . . . . . . . . . . . . . . 241.2.2.7 Miscellaneous Pathways . . . . . . . . . . . . . . . . 25

1.2.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271.3 Human Health Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

1.3.1 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281.3.1.1 Exposure Assessment . . . . . . . . . . . . . . . . . . 291.3.1.2 Toxicitv Assessment . . . . . . . . . . . . . . . . . . 35

1.3.1.2.1 Toxicitv Information for CarcinogenicEffects . . . . . . . . . . . . . . . . . . . . . . 35

1.3.1.2.2 T o x i c i t v I n f o r m a t i o n f o rNoncarcinogenic Effects . . . . . . . . . . . 36

1.3.1.2.3 Adjustment of Toxicitv Factors . . . . . . . 371.3.2 Stochastic Risk Characterization . . . . . . . . . . . . . . . . . . . . . 38

1.3.2.1 Stochastic Risk Estimation . . . . . . . . . . . . . . . 391.3.2.2 Stochastic Risk Description . . . . . . . . . . . . . . 43

1.3.2.2.1 Exposure Pathway Contribution Analysis . . . . 431.3.2.3 Uncertainty Analysis . . . . . . . . . . . . . . . . . . 50

1.3.2.3.2 Uncertainties Related to Estimates ofExposure Point Concentrations . . . . . . . 53

1.4 Ecological Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551.4.1 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

1.4.1.1 Exposure Assessment . . . . . . . . . . . . . . . . . . 561.4.1.2 Ecotoxicitv Assessment . . . . . . . . . . . . . . . . . 58

1.4.2 Stochastic Ecological Risk Characterization . . . . . . . . . . . . . . 591.4.2.1 Stochastic Risk Estimation . . . . . . . . . . . . . . . 591.4.2.2 Stochastic Risk Description . . . . . . . . . . . . . . 61

1.5 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641.5.1 Human Health Evaluation Summary . . . . . . . . . . . . . . . . . . . 65

1.5.1.1 Human Health Problem Formulation . . . . . . . . 65

ICF Kaiser InternationalFinal - March, 1994


1.5.1.2 Human Health Analysis . . . . . . . . . . . . . . . . 661.5.1.3 Human Health Risk Characterization . . . . . . . . 66

1.5.1.3.1 Stochastic Risk Estimation . . . . . . . . . . 661.5.1.3.2 Risk Description . . . . . . . . . . . . . . . . 681.5.1.3.3 Uncertainty Analysis

1.5.2 Ecological Evaluation Summary . . . . . . . . . . . . . . . . . . . . . 731.5.2.1 Ecological Problem Formulation . . . . . . . . . . . 731.5.2.2 Ecological Analysis . . . . . . . . . . . . . . . . . . . 741.5.2.3 Ecological Risk Characterization . . . ' . . . . . . . . 74

1.5.2.3.1 Ecological Risk Estimation . . . . . . . . . 751.5.2.3.2 Ecological Risk Description . . . . . . . . . 75

1.5.3 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 751.6 Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78


Yeoman Creek/Edwards Field Landfills - Stochastic iii

LIST OF TABLES

1 Exposure Pathway Contribution to Incremental LifetimeCancer Risks - Adjacent Residential Scenario . . . . . . . . . . . . . . . . . . . . . . 82

2 Exposure Pathway Contribution to IncrementalLifetime Cancer Risks - Future Adjacent Residential Scenario . . . . . . . . . . 83

3 Exposure Pathway Contribution to Incremental LifetimeCancer Risks - Occupational Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

4 Exposure Pathway Contribution - Adjacent ResidentialNoncarcinogenic Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

5 Exposure Pathway Contribution - Future AdjacentResidential Noncarcinogenic Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

6 Exposure Pathway Contribution - OccupationalNoncarcinogenic Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

7 Contaminant Contribution to Incremental LifetimeCancer Risk - Adjacent Residential Carcinogenic Scenario . . . . . . . . ... 90

8 Contaminant Contribution to Incremental LifetimeCancer Risk - Future Adjacent Residential Scenario . . . . . . . . . . . . . . . . . . 91

9 Contaminant Contribution to Incremental LifetimeCancer Risk - Occupational Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

10 Contaminant Contribution - Adjacent ResidentialNoncarcinogenic Scenario by Chemical . . . . . . . . . . . . . . . . . . . . . . . . . 94

11 Contaminant Contribution - Future AdjacentResidential Noncarcinogenic Scenario by Chemical . . . . . . . . . . . . . . . . . . . 95

12 Contaminant Contaminant - Occupational NoncarcinogenicScenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

13 Stochastic EHIs for Red-Winged Blackbird . . . . . . . . . . . . . . . . . . . . . . . . 9814 Stochastic EHIs for Mink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99


Yeoman Creek/Edwards Field Landfills - Stochastic iv

LIST OF FIGURES

2-1 Conceptual Pathway Model for Human Exposure . . . . . . . . . . . . . . . . . . . 100

2-2 Conceptual Pathway Model for Aquatic Ecological Exposure . . . . . . . . . . . . 101

2-3a Conceptual Pathway Model for Terrestrial Ecological Exposure . . . . . . . . . . 102

2-3b Conceptual Food Chain for the Red-Winged Blackbird . . . . . . . . . . . . . . . . 103

ICF Kaiser InternationalFinal - March. 1994


LIST OF ENCLOSURES

A Validated Remedial Investigation Data

B Human and Ecological Assessments - Screening

C 'Stochastic Human Health Exposure Assessment

D Human Health Toxicity Assessment

E Stochastic Average and Upper Bound Estimates of Risk forthe Human Health Assessment - By Media and Pathway

F Stochastic Terrestrial Ecological Exposure Assessment

G Ecotoxicological Assessment

H Ecological Stochastic Assessment



1.0 PUBLIC HEALTH EVALUATION

1.1 Introduction

This stochastic human health and ecological baseline risk assessment report for the Yeoman

Creek/Edwards Field Landfills Site (the Site) is intended to accompany the deterministic baselinerisk assessment conducted for this Site (ICF Kaiser, 1994). The deterministic baseline risk

assessment was produced in conjunction with the remedial investigation/feasibility study (RI/FS)report (Colder, 1994a) developed for the Site. The deterministic risk assessment built on thedraft risk assessment performed by Colder Associates (Colder, 1993a), which incorporated andmodified the conceptual site model for the potential contaminant exposure pathways at the Site,including exposure routes and potential receptors that were described in the PreliminaryMigration Pathway Screening Technical Memorandum (Colder. 1993b). The deterministic reportalso incorporated applicable comments contained in the United States Environmental ProtectionAgency (USEPA) memorandum of December, 1993 (Boice, I993a), and the results of additionalanalyses required by USEPA as indicated in the December, 1993 memorandum.

One of the comments made by the USEPA (Boice, 1993a) in response to the review of the draftdeterministic baseline risk assessment was that a stochastic analysis, if done for the Site, wouldhave to be submitted as a separate document rather than as a part of the deterministic sub mitral.Therefore, this stochastic investigation was produced not only to be viewed in parallel with thedeterministic baseline risk assessment (ICF Kaiser, 1994) but to be a stand alone risk assessmentand reference for stochastic risk assessment analyses performed for the Site. As a companion

report to the deterministic baseline risk assessment, this stochastic report relied on the samevalidated sampling data and assessed the risk to human health and ecological receptors assumingthe same exposure pathways and algorithms and the same toxicity data. As an independentinvestigation, all of the data and information upon which the stochastic risk assessment was basedis also included in this report. Hence, sections of this stochastic analysis that are in common withthe deterministic assessment are found in their entirety in both documents.

The critical difference in the stochastic and deterministic approaches, which is described in detailin the text, is the way in which the range of data available for each of the assumptions that aremade in conducting a risk assessment is used. While the deterministic analysis selects a singlevalue for a parameter or an assumption (i.e., soil concentration), the stochastic analysis



investigates the full range of values that could adequately and more accurately describe that valueor parameter. The major advantage of the stochastic approach is that more data is used toicharacterize risk. Uncertainty in a stochastic risk assessment can be identified and quantified.Because of the range of probable answers and quantified uncertainty, the Site manager is providedwith more information upon which to base decisions. These decisions will then be made on amore accurate reflection of the risks that may be associated with exposure to chemicals presentat the Site under the exposure conditions specified. Such decisions can be made based onanalyses in which the uncertainty has been more fully characterized, thereby allowing for riskmanagement decisions to focus on the critical remedial issues.

1.1.1 Purpose 1 Scope of Stochastic Baseline Risk Assessment

The purposes of a stochastic baseline risk assessment are the same as those for the deterministicbaseline risk assessment, which are (1) to evaluate the potential human health and ecological risksthat may be posed by chemical contamination at the Site in order to determine the need forremedial action; (2) to provide information to assist in the selection of the most appropriateremedial alternative if remediation is deemed necessary; and (3) to provide a basis fordetermining levels of chemicals that can remain at a site and still be adequately protective ofhuman health and the environment (USEPA, 1989). Another important aspect of this stochasticbaseline risk assessment is that it may also be used quantitatively to identify Site conditions(chemicals, exposure pathways, receptors) of greatest potential concern. Then, any remedialmeasures can be focused in these areas.

According to USEPA guidelines (USEPA, 1989), the baseline risk assessment generally consistsof four basic steps that can be summarized as follows:

• Data Collection and Evaluation. Determination of the nature andamount of chemicals that could be potentially encountered at theSite, and selection of those chemicals that are of potentialconcern for the assessment of the impact on human health orecological receptors.

• Exposure Assessment. Quantification of the extent, frequency,and duration of actual or potential exposure to chemicals bypathways relevant to the Site and activities of the potentialreceptors.'

• Toxicitv Assessment. Identification of the types of health effectsthat could be associated with exposure to these chemicals,

IGF Kaiser InternationalFinal - March, 1994


determination of the relationship between exposure (dose) andthe probability of occurrence of the health impact (response), anddiscussion of the related uncertainties.

• Risk Characterization. Estimation of the probability that anadverse health impact may occur as a result of exposure tochemicals in the amount and by the pathways identified and theuncertainty in those estimates.

Both the human health and ecological components of the baseline risk assessment for the Site areconducted for the above purposes using methodologies, required by USEPA guidelines (USEPA1989; 1991a; 1992a; 1992b; 1992c), A baseline risk assessment is intended to be site-specific;therefore, site-specific information is incorporated into the evaluation whenever available. In theabsence of site-specific information, default assumptions, as specified by USEPA guidance areused.

The intent of the stochastic baseline human health risk assessment is to provide a probabilisticapproach to evaluating potential risks at the Site (USEPA, 1992d, 1992e). These estimates ofrisk are developed under both current use and hypothetical future use scenarios, for theReasonably Maximum Exposed receptor, i.e., a potential receptor assumed to be exposed tomultiple chemicals by multiple pathways. Potential contaminant migration pathways are selectedthat represent reasonable contaminant migration routes. Exposure assessments are conducted thatmodel human exposure according to algorithms in relevant guidelines. Unlike the deterministicassessment in which two points - an average and an upper bound - were assessed, the stochasticanalysis utilizes distributions of values for each of the parameter values or assumptions. Adiscussion of the relevance of such estimates and the uncertainties associated with the estimatedrisks is an integral part of the baseline assessment. Variables (i.e., a chemical, pathway, or

parameter value) contributing most to estimates of risk or to the uncertainty in the risk assessmentare identified. Each of these steps is discussed in more detail in the following sections.

A stochastic analysis was also conducted for the ecological assessment. The terrestrial ecologicalassessment presented in this report estimates the risks to adult red-winged blackbirds, Agelaiusphoeniceus, nestling red-winged blackbirds, and mink, Mustela vison. Red-winged blackbird wasselected for evaluation based on information submitted in a June 7, 1993, memorandum fromEileen Helmer regarding the USEPA Region 5 Biological Technical Assistance Group (BTAG)meeting (Helmer, 1993). BTAG believed that a breeding red-winged blackbird was anappropriate species to enable evaluation of risks from contaminant exposures through the food-



chain and would provide a reasonable worst case estimate of the risk. Subsequently, USEPA(Boice, 1993a) has also required the inclusion of nestling red-winged blackbird and mink. Abrief qualitative evaluation concerning the aquatic community in Yeoman Creek also is presented.

1.1.2 Site Background

A discussion of Site background is presented in Section 1.3 of the Remedial Investigation (RI)report (Colder, 1994a).

1.1.3 Site Investigations and Data Sources

Several investigations at the Yeoman Creek/Edwards Field Landfills have been conducted sincearound 1960 and have included investigations performed by the Illinois Environmental ProtectionAgency (TEPA), the Lake County Health Department (LCHD), the USEPA Technical AssistanceTeam (TAT), and Colder Associates (Colder, 1994a). In 1960, environmental monitoring wasinitiated at the Yeoman Creek Landfill by LCHD, which began analyzing water samples fromYeoman Creek. Subsequently, sampling and analysis of surface soil, surface water, streamsediment, groundwater, and leachate seeps in the vicinity of the landfills have been conducted.In 1980 and 1987, the IEPA performed geologic and hydrogeologic studies at the Yeoman CreekLandfill that included borings and the installation of monitoring and leachate wells.Environmental monitoring has also occurred at the Edwards Field Landfill. The LCHD hasregularly inspected the landfill to determine if malodorous conditions or leachate seeps areoccurring. In addition, Warzyn Engineering obtained surface soil samples from the baseballdiamonds for chemical analyses and monitored ambient air. Field investigations for the RI beganin August, 1991. These investigations included installation and sampling of leachate andgroundwater wells, and sampling of surface water, leachate seeps and associated sediments,landfill gas, stream and pond sediments, and surface soil sampling.

Available background information and environmental data from the historical pre-RI studies andinvestigations and those from the RI are described in Section 1.3 of the RI and contained inAppendices B through H of the RI (Colder, I994a). The pre-RI data were used in thedevelopment of the RI work plan to assist in the selection of sampling locations (Colder, 1994a).Based on USEPA risk assessment guidance (USEPA, 1989), and the RI/FS work plan for theSite, only validated data were used in the quantitative risk assessment. Consequently, pre-RI datawere not used further in the risk assessment due to the following reasons (Colder, 1993a):



• In general, there is a lack of adequate documentation on the sampling proceduresused to obtain the historical data;

• Most of the historical data are not validated and are not accompanied by adequatequality assurance information to allow for validation in accordance with USEPAprotocols; and,

• The security of the Site prior to the RI was not adequate for the purposes of theRI data collection.

The validated data collected for the RI are of known, consistent quality as prescribed by CLPmethodology (Golder, 1993a), and have undergone additional data validation (Boice, 1993a). Thedata used in this risk assessment are presented in Enclosure A. The maximum concentrationsobserved in the historical (pre-RI) data are presented in Enclosure B, Table B-la for surface soils,sediments, and soil gas and Table B-lb for surface water, groundwater and leachate wells. Themaximum concentrations observed in the RI data are presented in Table B-lc for surface soils,sediments, and soil gas and Table B-ld for surface water, groundwater and leachate wells.

1.1.4 Stochastic Risk Assessment Methodology

The methodology for calculating the Incremental Lifetime Cancer Risk (ILCR) has traditionallybeen deterministic (i.e., it produces a single output for a set of single input parameter values).Use of these USEPA default parameters will result, in virtually all cases, in a risk estimate thatis above the 95% upper bound values and which incorporates large amounts of uncertainty(USEPA, 1989; 1992e). While this deterministic value is useful in providing a bounding estimateof risk, it does not provide adequate information with which to make risk management decisions.since it is unlikely that risks to any member of the receptor population will actually approach this

value.

Mathematically, incorporation of the high percentile parameter values used in deterministic RMEapproaches will often result in a value expected at the 99.9th percentile (Donohoe et al. 1990)of exposure or higher. A value at this percentile may be considerably higher (one to three orders

of magnitude [Donohoe et al. 1990]) than the 95th percentile value, around which the RME isintended to fall. Use of this value to make risk management decisions is therefore likely to resultin unnecessary and overly costly remediation.

An alternative approach to risk assessment can be achieved by taking into account the probabilitydistributions of possible values for each of the exposure parameters rather than relying on discrete


Yeoman Creek/Ed wards Field Landfills - Stochastic

parameter values. Simply stated, a stochastic analysis (e.g., Monte Carlo simulation) calculatesrisks repeatedly using randomly selected sets of values tor each trial. The sets of values arebased on combinations of input parameter distributions, rather than on single point valueestimates. The results of a stochastic simulation approximate the full range of possible risksassociated with a given chemical and pathway, and also provide estimates of the likelihood ofeach risk within the range.

Stochastic analysis involves calculating incremental lifetime cancer risks numerous times (e.g.,10,000 times) using parameter values selected randomly from each of the input parameters'distributions. The result is a frequency distribution of risk estimates from which the assessor canidentify the value corresponding to any specified percemile of the population (USEPA 1989).The final distribution can be divided into percentiles that define risks associated with theirprobabilities of occurrence.

Recent USEPA (1992d, 1992e) guidance has stated that it is preferable to develop this type ofdistribution of doses and risks across the population of interest. Any selected percemile of therisk distribution can easily be obtained, enabling the risk manger to comply with therecommendations of the USEPA guidance (USEPA 1992d, 1992e). According to USEPA'sexposure assessment guidance (USEPA 1992e), the use of stochastic analysis provides estimatesof central tendency and the upper end of the distribution of risk that should be used in qualitativerisk management decisions. Stochastic analysis has been applied to characterize distributions ofpossible exposures and risk for various pathways in risk assessments (Burmaster and vonStackelberg 1988, Eschenroeder and Faeder 1988, Iman and Helton 1988, and McKone and Ryan1989). The role of quantitative uncertainty analysis (i.e., output from a stochastic analysis) inrisk assessment has been presented by Finkel (1990).

The Latin Hypercube sampling method is similar to the pure Monte Carlo approach, whosemethod, theory, and programming algorithms have been described in several publicationsincluding Kalos and Whitlock (1986), Rubinstein (1981), and Fedra (1983). Latin Hypercubediffers only in the way by which values are sampled from the underlying probability distribution.Whereas pure stochastic modeling uses a random number approach, Latin Hypercube uses astratified random number approach. Latin Hypercube techniques are more efficient than pureMonte Carlo (i.e., it takes less iterations to achieve a stable distribution), however, there is nosubstantive effect on the outcome of an analysis associated with the choice of one of thesetechniques.

ICF Kaiser InternationalFinal -March, 1994


The quality of the stochastic analysis of risk is dependent on the quality of the distribution data

used for each of the variables (the exposure parameters). In many cases, assumptions regardingthe form of the distributions of the input parameters must be made because of data gaps. Thisresults in some degree of uncertainty associated with the stochastic analysis. In all cases whereuncertainty existed, conservative assumptions were used to fill data gaps. Unlike a deterministic

risk assessment, the uncertainties in a stochastic risk assessment are reflected in the variance ofthe output probability distributions.

The results of such modeling, when presented jointly with the results of traditional deterministicRME estimates, can provide useful information to risk managers. With this additionalinformation, more informed, technically sound risk management decisions can be made, inaccordance with recommendations of USEPA guidance on exposure and risk characterization(USEPA 1989, 1992e). These recommendations include (1) providing a ftill characterization ofrisk, (2) providing an expanded characterization of uncertainties in risk assessment, and(3) improving comparability and consistency among USEPA Offices and Regions.

1.1.5 Report Organization

This baseline risk assessment consists of five sections, including this introduction, and eightenclosures. Section 1.2, Problem Formulation, describes the selection of contaminants ofpotential concern (COPCs) from among the chemicals identified, and describes the selection of

receptors and exposure pathways to be evaluated. This section followed the same methodologyas that used in the deterministic baseline risk assessment for the Site (ICF Kaiser. 1994). Theexposure assessment was conducted using stochastic methodology as described in Section 1.1.5and Enclosure C. Section 1.3, Human Health Evaluation, provides the analysis (exposure andtoxicity assessments) and risk characterization (including an uncertainty analysis) comprising thehuman health baseline risk assessment. Section 1.4, Ecological Evaluation, provides the analysisand risk characterization comprising the ecological baseline risk assessment, which also employedstochastic methodology. Section 1.5, Summary and Conclusions, summarizes the assessment and

provides the conclusions drawn.

1.2 Problem Formulation


Yeoman C reeky Ed wards Field Landfills - Stochastic

The problem formulation process documented in this chapter consists of identification of Site

COPCs (Section 1.2.1), and identification of Site receptors and exposure pathways of potentialconcern (Section 1.2.2). This approach is the same as that used for the deterministic analysis.

1.2.1 Identification of COPCs

The baseline risk assessment scope includes identification of a list of COPCs (COPCs) for thehuman health and ecological investigations based on the chemical substances found at the Site.This list was developed using a step-wise approach. First, the concentration of a chemical in anenvironmental media was compared to background values in the respective media usingappropriate statistical methods. If the concentration of chemicals in sampling data wasstatistically significantly increased above background levels, the anaJyte was considered acontaminant. It was then compared to applicable or relevant and appropriate requirements(ARARs) and was subjected to the preliminary risk-based screening. Those substances found toexceed background concentrations were deemed to be contaminants; those contaminants found

to exceed ARARS or conservative preliminary risk-based screening benchmark concentrationswere deemed to be COPCs.

1.2.1.1 Background Screening

To determine if a chemical is a Site contaminant (as opposed to a naturally occurring substanceor a contaminant attributable to widespread anthropogenic activity), chemicals were screenedagainst background. A statistical analysis of Site sampling and background data was performed.Concentrations obtained in samples collected at the Site were compared to concentrations inbackground samples using a statistical test know as the Gehan test (Gehan, 1965), which is anextension of the well-known nonparametric Wilcoxon rank sum test (Gilbert, 1987, 1993). TheGehan test is valid when some of the samples are nondetects and, in fact, was designedspecifically to handle censored data. The Gehan test is a nonparametric test and, as such, canbe used regardless of the distribution of the data. Whenever there are no nondetects in the data,the Gehan test is equivalent to the Wilcoxon rank sum test. Chemicals present at concentrationsstatistically significantly different from background (p>0.05) were retained in the analysis(Tables B-2a and B-2b).



No background comparisons were performed for organic analytes; all organic compoundsdetected in a given environmental medium during the RI are conservatively regarded as being Sitecontaminants within that particular medium.

For soil samples, background samples were collected from stations 301 and 302, at off-Sitelocations as described in Colder (1993c). The concentration of a chemical in leach ate seep soilwas compared to the measured soil background value. Since surface soil and leachate seep soilwere evaluated together in the exposure pathway for soil, as directed by the USEPA (Boice.1993a), if the observed concentration for a chemical in either soil or leachate seep soil wassignificantly different from measured background levels, the chemical was retained for further

analysis. Magnesium was significantly increased above background in surface soil and leachateseep soil. Calcium was significantly increased in leachate seep soil only. All other inorganicchemicals were determined to be at levels comparable to background, i.e.. were not significantlydifferent from background (Table B2-a).

For surface water and sediments, background samples were collected from stations 8 and 9 (inthe golf course). Four rounds of analytical data from each station were collected; the values insurface water were compared to respective background values for the corresponding samplingevent as directed by USEPA (Boice, 1993a). For surface water, an inorganic chemical wasretained for subsequent analyses if it was determined to be significantly different frombackground in any sampling round. In the fourth round taken in August, 1993, no additionalbackground samples were taken; therefore, any metal detected in that round was retained onlyif it was not looked for or detected in previous sampling rounds or found to be statisticallydifferent from background in a previous round. Inorganic chemicals determined to be elevatedabove background in surface water included, arsenic, cobalt, cyanide, nickel, and zinc; inorganicchemicals either looked for or detected only in the fourth sampling round included antimony,beryllium, and cadmium (Table B-2b). Only lead was determined to be above background insediment samples (Table B-2a).

During the RI, groundwater target analyte list (TAL) parameters were analyzed in both filteredand unfiltered groundwater samples from both the shallow and lower outwash aquifers.Background samples were collected from three rounds of analytical data from monitoring wellMW-302 for the shallow groundwater flow system, and MW-301 for the outwash sand and gravelflow system. Filtered groundwater samples were compared to filtered background samples. Inaddition, as requested by USEPA (Boice, 1993a), the chemical concentrations in unfiltered


Yeoman Creek/Edwards Field Landfills - Stochastic LO

groundwater in either the shallow groundwater or the lower outwash groundwater were comparedto the unfiltered background samples for the respective aquifer. However, the comparisons ofvalues for unfiltered samples are questionable for reasons deserved in the RI (Colder, 1994a).That is,

"Conclusions drawn on the basis of comparisons between results for .unfilteredsamples would be inappropriate because the reported concentrations for manyparameters in unfiltered samples reflect the type and amount of particulates; boththe amount and type of paniculate depend upon the hydrostratographic unit thatis screened" (Colder, 1994a).

The statistical analyses of the filtered data are therefore considered more reliable. While the useof unfiltered water samples is a common practice in site assessments, as per USEPA guidance(1989), comparisons to filtered water, which is the relevant data when residential drinking wateris the pathway, are included in this investigation. Results from shallow groundwater monitoringwells MW-202, MW-204, MW-206, MW-215, and MW-402 were not included in the riskassessment, as per USEPA instructions (Boice, 1993a) because they were not screened in theaquifer. Similarly, the results from MW-203 and MW-405 for the lower outwash aquifer werealso excluded from the assessment (Boice, 1993a). In filtered lower outwash groundwater, onlycalcium, magnesium, potassium, and sodium were elevated above background (Table B-2a). Inunfiltered lower outwash groundwater, only levels of sodium were significantly increased. Inshallow groundwater, iron was significantly increased in filtered samples, and copper, iron, lead,and potassium were elevated in unfiltered samples (Table B-2a).

Some of the Site contaminants — calcium, magnesium, potassium, sodium — are essentialnutrients for human and ecological receptors and are unlikely to be toxic under the environmentalconditions at the Site. As such, these four contaminants are not subjected to the preliminary risk-based screening procedure and were not considered further in the risk assessment.

Comparison to background was more complex for selection of chemicals of concern forecological receptors. With the statistical approach, it may be possible to eiiminate a chemicalfrom one media (e.g., surface soil), but not from another (e.g., sediment). This would affect theweighted exposure point concentration used in the soil pathway. Furthermore, I each ate soil doesnot have background data. In situations where a chemical was below background for onemedium but above for the other medium the chemical was remained in the screening processevaluation because the receptor species may still be exposed to plants, insects, or terrestrial



animals influenced by these concentrations. In cases where concentrations of chemicals in bothsurface soil and sediment were below background, then the leachate sample was examined todetermine if the chemical may be removed from the terrestrial evaluation. If leachate soilconcentrations were below background soil concentrations then it was unlikely that the leachatesoil contributed extra amounts of the respective chemical. All of the inorganic chemicals wereeliminated for the soil pathway with this approach except for lead.

Those inorganic chemicals identified as Site contaminants were compared to ARARs and weresubjected to preliminary risk-based screening, along with all organic chemicals, as documentedbelow in Sections 1.2.1.2 and 1.2.1.3.

1.2.1.2 Comparison to ARARs

Comparison to ARARs was conducted for all Site contaminants defined in Section 1.2.1.1 andfor all organic constituents detected. The maximum observed concentration of each contaminantwithin each medium was compared to relevant ARARs (Enclosure B, Tables B-3 and B-4).Chemicals were screened separately against human health or ecological ARARS. Contaminantswith maximum concentrations exceeding relevant criteria were deemed of potential concern andwere retained for further risk evaluation.

For the human health assessment, the maximum groundwater and surface water concentrationswere compared to human health water quality criteria as follows:

• Primary maximum contaminant levels, MCLs (40 CFR 141);

• Maximum contaminant level goals, MCLGs (40 CFR 141);

• Secondary MCLs (40 CFR 143);

• Human water quality welfare criteria, HWQWC (USEPA, 1986a); and,

• Illinois Groundwater Quality Standards, IGQS

While there is no MCL for lead, an action level of 0.015 mg/L has been established (USEPA,1991b). Maximum concentrations of lead in groundwater or surface water were compared to thislevel. Since hexavalent chromium was detected in a leachate well during the RI, it is assumed


Yeoman Creek/Edwards Field Landfills - Stochastic 12

that all chromium found in other media are in the hexavalent form as requested by USEPA(Boice, 1993a)1.

The maximum concentration for most chemicals was below relevant ARARs tor the human health

assessment; however, no chemicals were eliminated from further consideration if theconcentration was lower. Those chemicals elevated above an ARAR are listed in Table B-3. Inthe lower outwash ground water samples, pentachloro phenol was present at a maximum detectedconcentration of 0.003 mg/L in the only sample in which it was detected, which is in excess ofthe MCL and the IGQS value of 0.001 mg/L. In shallow groundwater, the maximumconcentrations detected for pentachlorophenol, benzene, and vinyl chloride were above theirrespective MCL or IGQS values. Vinyl chloride was only detected in shallow groundwater andonly in two samples - one at 0.002 mg/L and the other at 0.003 mg/L. The MCL for vinylchloride is 0.002 mg/L. The maximum detected value for benzene was 0.02 mg/L compared tothe MCL and IGWs of 0.005 mg/L. As with the lower outwash aquifer, pentachlorophenol wasdetected in only one sample, at a concentration of 0.002 mg/L compared to an MCL of0.001 mg/L. While elevated compared to the maximum detected value, the 95% upper boundon the arithmetic average concentration for benzene and pentachlorophenol were lower than eitherthe MCL or IGQS. The maximum detected concentration for lead in the shallow groundwaterwas 0.085 mg/L, which is above the action level of 0.015 mg/L; however, the 95% upper boundon the arithmetic mean was well below this value. The action level for lead is applicable tosource waters, and hence to groundwater; however, the intent of the action level is to controllevels between the source and the residential user (USEPA, I991b). The final action level forlead is only exceeded if the level of lead in more than 10% of targeted tap samples is greater than0.015 mg/L (USEPA 1991b). In surface water, no chemicals that were determined to be elevated —•'above background values exceeded their respective MCL or IGQS. The relevance of these isdiscussed in Section 1.5.

Chloride and sulfate were designated as COPCs in surface water, and groundwater because theirmaximum concentrations exceeded secondary MCLs. These secondary MCLs are not based on

1 This assumption is conservative since hexavalent chromium is rarely found in the environment dueto thermodynamic instability. It is readily reduced in the presence of oxidizable organic matter, of whichthere is no shortage at the Site due to the proximity of marshlands, and hexavalent chromium, whenadded to soil, can be expected to rapidly reduce to the trivalent state (Adriano 1986). No hexavalentchromium has been detected in groundwater or surface water despite extensive sampling and analysis;in fact, USEPA-5 allowed hexavalent chromium to be deleted from the analyte list for the third roundof RI groundwater sampling and analysis.



lexicological concern, but on human welfare considerations {i.e.. taste, smell, and other aestheticconsiderations). Therefore, since these two contaminants lack USEPA-approved toxicity criteria.they were not carried through the remaining phases of the risk assessment. Note that theammonia values presented in the RI are expressed as total ammonia (NH3 and NH4 as N), at anestimated temperature of 15°C and pH of 7.0 consistent with Site conditions, most of the

ammonia exists in water in the ionized form not available for transport by way of the inhalationpathway. Therefore, ammonia was not evaluated further.

For the ecological assessment, chemicals were screened against:

• Ambient Water Quality Criteria, AWQCS; and• NOAA Sediment Quality Criteria (1990).

The comparisons to these ARARs are listed in Table B-4. The maximum concentration of eachanalyte in surface water was compared to their respective AWQCS. The maximum detectedconcentrations of Aroclor-1248, antimony, cadmium, cyanide, and zinc were elevated above theirrespective AWQCs. Concentrations of chloroform, pentachlorophenol, phenanthrene, arsenic,and nickel were below their criterion and thus not evaluated further in the ecological analysis forsurface water. See section 1.2.1.2 for further details concerning the significance of theexceedances.

Maximum detected concentrations of both inorganic and organic chemicals in sediments then werecompared to sediment quality screening guidelines. Chemicals detected in only sediment couldbe eliminated at this stage. Acenaphthylene, di-n-octylphthalate, chloroform and toluene werenot evaluated further. See section 1.2.1.3 for further details concerning the significance of theexceedances. All remaining potential Site contaminants were evaluated in the preliminary riskscreen described in the next section.

1.2.1.3 Preliminary Risk Based Screening

Chemicals remaining after screening against background were evaluated in a preliminary,deterministic risk-based screen using the same approach as the deterministic base line riskassessment (ICF Kaiser, 1994). For all media and pathways in the human health assessment,risk-based screening levels were defined using contaminant-specific slope factors (SFs), referencedoses/concentrations (RfDs/RfCs), conservative residential exposure parameters, a lifetime



incremental cancer risk (ILCR) of 1 x 10"*, and a hazard quotient (HQ) of 0.3. as appropriate.Media- and pathway-specific exposure algorithms used in this screening process are tbund in

Enclosure C.

While a lO"6 cancer risk is generally considered to be USEPA's benchmark, a risk range of 10'6

to 10"4 is used by USEPA at Superfund sites in the evaluation of the need for remedial activities,and is considered to be an acceptable risk range (USEPA. 1991b). The USEPA has issuedfurther guidance clarifying the role of risk assessment in the Superfund process (D. Clay, USEPA[Memorandum to USEPA Regional Waste Management, Emergency and Remedial Response,Hazardous Waste Management, and Hazardous Waste Division Directors] April 22, 1991). Thisdirective states that where the cumulative current or future carcinogenic risk to an individual isless than 10"4, and where the noncarcinogenic HQ is less than one, action generally is nntwarranted unless there are adverse environmental impacts.

Although an HQ of 1.0 is considered a point of departure; an HQ less than one is generallyconsidered to be without risk of adverse impacts. An HQ of greater than one does notautomatically indicate an adverse outcome. An HQ of 0.3 was used to account for the fact thatmultiple contaminants or multiple pathways could result in additive effects not accounted for inthe screening procedure. It must be noted that using the maximum detected concentration alongwith conservative residential exposure assumptions in the screening procedure imparts additionaloverall conservatism to the results to ensure that the actual contaminants of concern, as definedat the conclusion of the baseline risk assessment, are retained. In addition, all the HQ were basedon exposure to a child, age 6. A child would receive a higher estimated exposure than the adult.

Operationally, all organic chemicals and inorganic chemicals, which were above background,were evaluated in this risk-based screen. Separate, risk-based levels, termed ScreeningConcentration Noncancer (SCNs) or Screening Concentration Cancer (SCCs) were developed foreach exposure pathway for each media (see Section 1.2.2 and Enclosure C). A chemical wasretained if the maximum detected concentration exceeded either the SCN or SCC for any pathwayevaluated. Chemicals whose risk-based screening levels were below 1 x 10* or 0.3 were notautomatically eliminated. Rather, the contribution of the estimated risk for that contaminant tothe total risk for the pathway was considered. Those chemicals with estimated risks abovescreening levels, or for those chemicals that contributed significantly to a pathway-specific riskestimate, even if the total pathway risk was below 1 x 10"6 or an HI of 0.3, were retained so thattheir contribution across all pathways for the RME could be evaluated.



Table B-3 provide the initial risk-based screening results for each environmental medium of

interest. No toxicological or regulatory information was encountered for several organiccontaminants, including: in sediment — dibenzofuran; in surface water — 4-nitrophenol. Theconcentrations of these substances are quite low. The concentrations in question are below SQLsreported in corresponding background samples. As such, these substances are not given furtherconsideration in this report.The final step of the ecological screening process was also a toxicity screening calculation tofocus the ecological risk assessment on the "most significant" COPCs (i.e.. those contributinggreater than 90% or more of the total potential risk) for the soil/sediment/leachate seep soilexposure route. In this approach, two of the most important factors in determining the potentialrisk to an ecological receptor - toxicity and Site concentrations - were used to calculate therelative contribution to overall risk for each chemical (Table B-4a). Chemical-specific screeningrisk factors were calculated for each chemical using the following equation:

R, = (CJCTSV,)

where:R» = Risk Factor for chemical i in the specified mediaCm = Weighted mean concentration of chemical i in the specified mediaTSVj. = Toxicity screening value for chemical i, i.e., 1/LD50)

Oral lethal doses (LD^) were located in the literature for mice. When chemical-specific mouseoral LDjo values could not be located, rat oral LDW values, if available, were converted toequivalent mouse LDW values using this equation:

1/3Estimated Mouse LD^ = Rat LDw/(Wmouse/Wrat)

where:Wmouse = Weight of mouse (20 g)Wrat = Weight of rat (100 g)

Each chemical-specific screening risk factor (R-J was then summed to obtain a total screening riskvalue. The relative contribution to overall risk was then calculated by dividing each chemical-specific screening risk factor (RJ by the total screening risk value. A chemical was selected forfurther evaluation if it contributed greater than 1% of the total overall risk (i.e., the chemical-



specific calculated relative risk value > 1.0 E-2). The calculated screening risk factors provide

information on the relative contribution to risk posed by chemicals on-Site or purposes ofscreening.

Organic chemicals were screened separately for the surface water pathway and for the soil-relatedpathways. From this screen the following organic chemicals were selected for-further evaluationin the soil-related pathways: acenaphthene, anthracene, benzo(a)anthracene,benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene,dibenzo(a,h)anthracene, dieldrin, fluorene, and indeno(I,2,3-cd)pyrene for the ecologicalassessment. Lead was selected as the only inorganic chemical of potential concern to be furtherevaluated because it was elevated above background in sediment. Professional judgement wasused as a basis for adding chemicals to the final evaluation list that had been dropped at earlierstages. The aroclors (Aroclor-1242, Aroclor-1248, Aroclor-1254) were added back into the soiland sediment pathway evaluations because they are known to bioaccumulate. For the surfacewater pathway (ingestion) only cyanide, zinc, and acetone were retained. Although some of the

chemicals eliminated from surface water are known to bioaccumulate (e.g., Aroclor-1248 andmercury), these chemicals were detected at low concentrations and very low frequencies insurface water so any contribution they might have to an overall chemical risk through thisingestion pathway would be negligible.

1.2.1.4 CQPCs

The COPCs for each of the environmental media of interest, as defined in Section 1.2.2, arepresented below. For the human health assessment, a chemical was retained if the maximumdetected concentration exceeded either the SCN or SCC for any pathway evaluated. Chemicalswhose risk-based screening levels were below 1 x 10"6 or 0.3 were not automatically eliminated.Rather, the contribution of the estimated risk for that contaminant to the total risk for the pathwaywas considered. Those chemicals with estimated risks above screening levels were retained.Those chemicals that contributed significantly to a pathway-specific risk estimate, even if the totalpathway risk was below 1 x 10"* or an HI of 0.3, were also retained so that their contributionacross all pathways for the RME could be evaluated. These chemicals are indicated by anasterisk.

Surface Soil/Leachate Seep Soil COPCs

ICF Kaiser InternationalFinal- March, 1994


Arocior-1242Aroclor-12484,4'-DDT*bis(2-ethylhexyl)phthalate*dieldrinbenzo(a)pyrenebenzo(b)fluoranthenefluoranthene*p.p'-methoxychlor*phenanthrene*pyrene*

Surface Water COPCs

Aroclor-1248arsenic*beryllium*antimony*acetone*cadmium*bromodichloromethane*pentachlorophenol *methylene chloride*

Sediment COPCs

Aroclor-1242*Aroclor-1248*Aroclor-1254*benzo(a)pyr'ene*benzo(b)fluoranthene*dibenzo(a,h)anthracene*4,4'-DDT*bis(2-ethylhexyl)phthalate*fluoranthene*phenanthrene*pyrene*pentachlorophenol*

SoU Gas COPCs

benzeneethylbenzenetetrachloroethenetoluene*trichloroethenevinyl chloride*

Shallow Groundwater Flow System COPCs

• benzene• bis(2-hexylethyl)phthalate



vinyl chloridemethyiene chloride*di-n-butylphthalate*copper*1,2-dichloroethane (total)*acetone*chlorobenzene*butylbenzylphthalate*

Outwash Sand and Gravel Flow System COPCs

bis(2-hexylethyl)phthalate*benzene*chloroform*methyiene chloride*di-n-butylphthalate*acetone*butylbenzylphthalate*

For the ecological assessment, a blend of surface soil, sediment, and leachate seep soilconcentrations was used. The COPCs for this btend and for surface water are listed below. Thechemicals retained were based on screening procedures discussed previously.

Surface Soil, Sediment, and Leachate Seep Soil COPCs

leadacenaphthaleneanthraceneAroclor-1242Aroclor-1248Aroclor-1254benzo(a)anthracenebenzo(a)pyrenebenzo(b)fluoranthenebenzo(k)fluoranthenebenzo(g,h,i)perylenechrysenedibenzo(a,h)anthracenedieldrinfluoreneindeno(l,2,3-cd)pyrene

Surface Water COPCs

cyanidezincacetone



1.2.2 Identification of Receptors and Exposure Pathways of Potential Concern

The deterministic baseline risk assessment also included determination of the principal exposurepathways and the potential receptor populations for both the human health and ecologicalassessments (ICF Kaiser, 1994). These were also used in this stochastic analysis. Risks wereestimated and characterized for those pathways and receptors of potential concern, so that theneed for remediation could be determined and, if necessary, Site-specific remedial actionobjectives could be established.

An exposure pathway is a specific contaminant transport process, often involving multipleenvironmental media, that terminates in a contaminant exposure to a human or ecologicalreceptor, or at least the potential for such an exposure. An exposure pathway can consist of thefollowing five elements (USEPA, 1989):

A contaminant source;A contaminant release mechanism;An environmental transport medium;An exposure route; andA receptor.

An exposure pathway analysis is conducted, as illustrated in Figure 2-1, based on the Site-wideconceptual model to identify the potential release mechanisms, transport media, and exposurepathways that could be operative at a Site (USEPA, 1989). As shown in Figure 2-1, currentlythere could be three operative contaminant release mechanisms at the Site: leaching, soil gasdiffusion, and wind erosion. Further, leachate could enter the groundwater or be transported byoverland flow to surface water. Affected groundwater and surface water in contact with the soilcolumn could allow for soil (or sediment) contamination, and shallow groundwater discharges toYeoman Creek could contribute further to surface water impacts. Volatile compounds in soilcould be transported, as soil gas and could be released to the ambient air or diffuse intobuildings. From among the potential release mechanisms and exposure pathways, those mostlikely to occur and contribute to exposure are evaluated quantitatively.

Exposure pathways can then be postulated under current conditions and for potential futureconditions (USEPA, 1989). Currently, receptors could come in contact with soil at the Site (seepand/or surface soil) or with sediment and surface water in Yeoman Creek adjacent to the Site.The potential routes of human exposure under current conditions then could be through ingestionor dermal contact with soil. Potential surface water and sediment routes are ingestion and dermal



contact while wading in Yeoman Creek. Exposure could occur under current conditions tovolatile organics in soil gas by the inhalation route. Currently, groundwater at the Site is notbeing used for a residential water supply; therefore, exposure to chemicals in groundwater is notan operative exposure assessment pathway under current conditions. As pan of this baseline,however, a future use scenario assumes that groundwater could be used by adjacent residents.Therefore, under a hypothesized future use, exposure pathways could include exposure tochemicals in groundwater by way of residential water use and include ingestion and dermalcontact with chemicals in groundwater, and inhalation of volatile chemicals released fromgroundwater during use. In addition, while not likely, ingestion, inhalation, and dermal contactdirectly with the contaminant source could occur.

Figure 2-1 illustrates the exposure pathways for human exposure, and depicts the three potentialreceptors to be evaluated:

• Adjacent Residential (current conditions);• Adjacent Residential (future conditions including future groundwater use); and• Site Occupational (applies to both current and future conditions)

For the residential receptors (both current and potential future), estimates of exposure, and hencerisk, were evaluated and the 50th, 90th, and 95th percentile results reported. For estimates ofcancer risk, the receptor was assumed to be a person who lived adjacent to the Site for up to 30years. However, for estimates of exposure and to assess the potential for noncancer affects, a6-year-old child was selected, which results in higher estimates of intake than for the adult.Estimates of exposure and risk are determined for the Reasonable Maximum Exposure situation.This receptor is assumed to be exposed to multiple chemicals by multiple pathways concurrently.As directed by USEPA (Boice, 1993a), this can be conceptualized as follows: The RME isassumed to live 30 years (upper bound case) adjacent to the Site and as a child lives and goes toschool adjacent to the Site. With the adult receptor, however, it is reasonable to assume that aportion of day is spent away from the Site. The exposure pathways and exposure parametersused in the human health evaluation are discussed Section 1.3 and Enclosure C.

Figure 2-2 and 2-3 illustrate a conceptual pathway model for potential ecological receptors.Figure 2-2 depicts a conceptual pathway model for aquatic receptors. However, the aquaticcommunity within Yeoman Creek is not quantitatively evaluated because the intermittent natureof its flow regime precludes the establishment of an aquatic community; in fact, the creek does



not support fish. Furthermore, benthic macroinvertebrate surveys indicated low benthicmacro in vertebrate abundance and low taxa richness. Therefore, potential aquatic receptors werenot assessed quantitatively. Further, due to the large flow rate of the Waukegan River, relativeto the creek and groundwater discharge rates, and the lack of sediment transport (Klewin, 1994),it is unlikely that the river's aquatic community is impacted in any way by the Site. Therefore,a quantitative evaluation of the aquatic ecological effects in the Waukegan River is also notconsidered.

Figure 2-3a illustrates the conceptual pathway model for terrestrial ecological exposure, andFigure 2-3b illustrates the conceptual food chain for the red-winged blackbird, the indicatorspecies for the terrestrial ecological assessment. Leaching is seen, in Figure 2-3a, to be therelease mechanism of potential concern. The exposure routes identified would be ingestion, ofpotentially affected plant and animal matter, as well as surface water. At the request of USEPA(Boice, 1993a), soil/seep soil and sediment ingestion was also considered. Also at the requestof the USEPA (Boice, 1993a), the nestling red-wind black bird and mink were also evaluated asterrestrial receptors. The relevance of the mink as a representative ecological receptor isdiscussed in Section 1.4. While other exposure routes, such as dermal contact, may be possible,it is assumed that the ingestion route, given the blackbird's high metabolic rate and consequenthigh food consumption rate, is by far the most dominant. The exposure pathways and exposureparameters used for the ecological assessment are discussed in Section 1.4 and Enclosure F.

Further discussion of each pathway to be evaluated quantitatively is provided in the followingsubsections that are organized by environmental medium. Section 1.2.2.7 identifies andqualitatively evaluates other pathways considered.

1.2.2.1 Surface Soil Pathway

Current and future exposure to residential and occupational receptors were assessed for thesurface soil pathway by way of ingestion and dermal contact. As required by the USEPA (Boice,I993a), exposure to chemicals has been assessed using a soil/leachate seep soil blend. Under thisexposure scenario it was assumed that 30% of the soil either ingested or contacted dermally wasleachate seep soil, while the remaining soil contributor, 70%, was from surface soil. Thesampling data in Enclosure A for each chemical in each media (leachate seep soil and surfacesoil) was used. Chemical concentrations were assumed to be at steady-state without attenuationover the course of exposure (up to 30 years). The exposure assessment assumed unrestricted



access to the contaminated soil/leachate seep soil. Residents were assumed to contact the

contamination as frequently as if it were in their backyard. Children, as the receptor fornoncarcinogenic effects, were assumed to play in the contaminated soil and ingest it regularly.

Exposures of red-winged blackbird adults and nestlings, and mink to soil COPCs were assessedthrough the ingestion of terrestrial plants (red-winged blackbird adults), insect (Crustacea, red-winged blackbird adults and nestlings, and mink) and mice (mink). Furthermore, incidentalingestion of surface soil, surface water sediment, and I each ate soil, which could occur duringforaging and preening or grooming, was evaluated for adult red-winged blackbird and mink.

1.2.2.2 Surface Water Pathway

Current and future adjacent residential exposures to the surface waters of Yeoman Creek wereevaluated with respect to dermal contact (wading) and ingestion (incidental while wading).Residents, including children, were assumed to wade in Yeoman Creek as if the residents of theadjacent area had unrestricted access to the Creek. The parameter values used and exposureequations are found in Enclosure C.

The terrestrial ecological evaluation included the assessment of ingestion of Yeoman Creek watersby red-winged blackbird adults and mink. The parameters for these exposure assessments arefound in Enclosure F.

Ammonia, chloride, and total dissolved solids (TDS) levels increased from upstream todownstream samples in Yeoman Creek. Furthermore, iron, chloride, sulfate, and sulfideexceeded their water quality criteria for freshwater aquatic life. However, as indicated inTchobanoglous and Schroeder (1985) these chemicals are often present in surface water as theresult of natural processes. For instance, significant quantities of chloride and sulfate arecommonly found in surface water as a result of water contact with minerals, soils, and rocks orthe addition of rain water. Ions like chloride produce minimal ecological effects overconcentration ranges of several orders of magnitude. Ammonia, chloride, and sulfide can resultfrom the decomposition of organic matter by bacteria the environ -nt. Sultate is taken up byplants and microorganisms for the production of cell tissue. Sulfate can be reduced to sulfide bya small group of anaerobic bacteria known as sulfate-reducing bacteria. Thus, the appearance



of these chemicals is not unexpected and most aquatic organisms can probably regulateconcentrations of these chemicals in their bodies.

1.2.2.3 Surface Water Sediment Pathway

Dermal contact with and incidental ingestion of the surface water sediments df Yeoman Creekwere evaluated in the human health baseline risk assessment. Under both current and future useconditions, residents of the adjacent area were assumed to contact the sediments of Yeoman Creekwhile wading. Concentrations of chemicals in surface water sediments were assumed to be atsteady-state and remained at these levels without attenuation for the entire assumed exposureduration.

Terrestrial receptors (red-winged blackbird adults and nestlings, and mink) were assessed in theecological evaluation, through the ingestion of aquatic plants and insects inhabiting the sediments.Although dietary fractions derived from terrestrial and aquatic sources were encountered in theliterature, these values were not directly used because the Site is very different from thosereported in the literature (i.e., data on marsh areas surrounded by urban areas were notavailable). Thus, the sediment, surface soil, and leachate soil contaminant of potential concernconcentrations have been combined for the terrestrial scenarios such that an evaluation isconducted on weighted average concentrations proportioned by the approximate areal extent ofcreek and land surface in the study area and on feeding information from the scientific literature.

1.2.2.4 Soil Gas Pathway

Current and future residential exposures through the soil gas pathway were assessed in the humanhealth evaluation. In this assessment, soil gas was assumed to migrate to adjacent buildingswithout attenuation. Diffusion through foundations is assumed to result in a steady-stateconcentration of volatile substances in indoor air. Vinyl chloride, which was detected ingroundwater, but not in soil gas, was included in this analysis. Vinyl chloride was assumed tobe present at one-half the detection limit. This was included at the request of USEPA (Boice,1993a). Potential receptors include adjacent residents in buildings with basements (Colder.1993a).



1.2.2.5 Groundwater Pathway

There are no active drinking water wells installed in the shallow groundwater flow system(Colder, I993b). There are no current uses of the shallow groundwater flow system, and theentire surrounding area in the City of Waukegan is served by municipal water. As noted in theRI report (Colder, 1994), the nature of this formation makes it highly unlikely to exploit it as afuture source of groundwater supply. Nevertheless, a future exposure scenario for the shallowgroundwater aquifer was evaluated in the baseline risk assessment. Likewise, there are currentlyno active drinking water wells in the outwash sand and gravel flow system. Nevertheless, thefuture residential exposure scenario is evaluated to determine risks associated with the possibility,although remote, that wells would be installed in this flow system. If that were to be the case,the future groundwater use scenario was evaluated through the assessment of ingestion and dermalcontact and inhalation of volatile substance exposure pathways in the human health evaluation.Future groundwater use by residents is assumed to include drinking, food preparation, bathing,and other household uses. With this scenario, it was assumed that concentrations were at steady-state and that no attenuation over the exposure duration occurred. Estimates of exposure and riskwere based on both unftltered and filtered groundwater samples. Although it is likely that anyfuture groundwater would reach the residents only after being filtered, exposure was assumed tobe to either filtered or unfiltered groundwater in these scenarios.

1.2.2.6 Leachate Seep Soil Pathway

Although the extent of such affected areas is minimal and the frequency associated with exposuresis regarded as small, the leachate pathway was quantitatively evaluated for both human health andecological assessments. For human health, the leachate seep soil is considered as pan of thesurface soil pathway, and is assumed to contribute 30% to the total soil ingestion and dermalcontact pathways. Because the leachate seep sediments are in close proximity to the wetlandhabitat of the red-winged blackbird, chemicals in leachate are also assessed for the ecologicalassessments. The weighted exposure point concentrations, discussed in brief in Section 1.4,attempt to take into account the limited area! extent of leachate c ntaminant. For more specificdetails see Enclosure F.



1.2.2.7 Miscellaneous Pathways

Identification of the preceding exposure pathways of potential concern was the result of aniterative process involving interaction with USEPA-5. Several potential exposure pathways forthe Site were first proposed in a preliminary migration pathway screening technical memorandumin April,' 1993 (Colder, 1993b). The USEPA-5 responded with comments'on the screeningmemorandum in May, 1993 (Boice, 1993b). This letter indicated the agency's desire to see aqualitative evaluation for the following exposure pathways. Those pathways that wererecommended for qualitative evaluation by USEPA-5, and that are evaluated below in such amanner are:

Future Residential Development on the landfills—• Dermal contact with and ingestion of landfill waste;• Inhalation of landfill gas; and,• Dermal contact, ingestion, and inhalation of ground water contaminants.

Direct contact of any kind with landfill waste would likely be considered to be unacceptable. Theconstruction of a dwelling on the landfills is considered to be a highly unlikely event, especiallysince deed restrictions banning all development and public access are in place for nearly all ofthe Yeoman Creek Landfill. Consequently, the probability of risk arising from inhalation oflandfill gas or use of groundwater in a future residential development scenario on the landfills isjudged to be remote. The quantitative evaluation of the groundwater use under the FutureAdjacent Residential Scenario provides a numeric benchmark from which qualitative riskestimates related to use of groundwater for on-Site dwelling on the landfills could be derived.

Future Park Development on the landfills—

• Dermal contact with landfill waste;' Inhalation of landfill gas; and,• Ingestion of groundwater.

Deed restrictions on the use of Yeoman Creek make it highly unlikely that future parkdevelopment will occur. (Similar deed restrictions are anticipated for Edwards Field Landfill inMarch of 1994.) In addition, ambient air monitoring on the landfills has shownthat the riskarising from inhalation of landfill gas under the park development scenario is expected to benegligible. As stated above, groundwater use for a hypothetical Future Adjacent ResidentialReceptor was assessed; use under hypothetical recreational conditions would be significantly less.



No Development —

• Ingestion of Lake Michigan water:• Inhalation of landfill gas during on-Site excavation;• Fire and explosion during on-Site excavation; and,• Dermal contact with surface soil on the landfills.

Given the enormous volume of Lake Michigan, even just the near-shore volume in the vicinity

of the Waukegan River, it is fairly obvious that ingestion of drinking water derived from the lakewould have virtually no risk that could be attributed to Yeoman Creek surface water. In addition,no sediment transport to down stream locations has occurred (Klewin, 1994).

Municipal landfills are a historical source of methane production. Methane is produced by theanaerobic biodegradation of waste products. Methane has been found to migrate laterally throughpermeable soils from the source landfill. Explosions have occurred in homes and businesses nearlandfills due to methane migrating into confined, unventilated places in basements and crawlspaces and accumulating at high concentrations. However, several methods are available toeliminate these explosion risks that can be implemented. There are gas inhalation and explosionrisks associated with any excavation undertaken on any landfill. Finally, as recognized inUSEPA-5's letter (Boice, 1993b), there are no data for landfill cover material soil quality toallow for a quantitative evaluation of exposures to on-Site soils. It is likely that final remediationwill eliminate any exposure pathways associated with landfill cover soils; however, if such doesnot turn out to be the case, additional data collection may be necessary, and the followingpathways would need to be evaluated at that time:

• Direct contact with landfill cover soils;• Inhalation of fugitive dust from cover soils; and,• Exposure to cover soils eroded and transported off the landfill surfaces.

Other pathways were considered, but are not regarded as being of concern (Colder, 1993a).Such pathways do not require either qualitative or quantitative evaluation at this time (Boice,1993b). These pathways, and a brief rationale for their exclusion, are:

• Inhalation of landfill gas in ambient air — Preliminary air monitoring testsindicated that volatile organic compounds were not being released from thelandfill, or if released, concentrations, were not large enough to be detected. Inaddition, release to the above ground air and the transport to a nearby receptorrepresent immediate and significant dilution processes. Calculations are foundin Enclosure B.



• Ingestion of fish from Yeoman Creek — Yeoman Creek is an intermittent creekthat is not tree flowing and does not support fish considered to be edible. Thiscreek does not serve as a recreational fishing source for the surrounding area.

• Current residential exposures to groundwater — All residents in the area and inthe town of Waukegan are on municipal water supply, which is not drawn fromeither on-Site aquifer. No current residents use the shallow or outwash aquifersfor residential water supplies.

• Exposures to bedrock groundwater — No contamination was observed in thebedrock aquifer due to the overlying aquitard and there are no residents withaccess to this source for potential residential use.

USEPA-5's letter of June 9, 1993 (Boice, 1993b), also provided pathway recommendations, ofthe region's BTAG, pertaining to the ecological component of the baseline risk assessment.These recommendations formed the basis for the adult red-winged blackbird scenario. However,one specific BTAG recommendation will not be addressed quantitatively. This recommendationconcerns the evaluation of polychlorinated biphenyls (PCBs) in groundwater. The sampling datafor either aquifer did not detect any PCBs in groundwater (see Enclosure A).

Other comments regarding the inclusion of leachate seep soil in the analysis because of theassumed potential for redistribution into wetlands has been addressed in this assessment, asrequested by USEPA (Boice, 1993a). As discussed in Section 1.4, concentrations for surfacesoil, leachate seep soil, and sediment were used in a weighted combination in the soil pathwaysfor ecological receptors. Synergistic interactions are not expected to occur at environmentaldoses; therefore, that potential is addressed by assuming additive effects. Lastly, as also requiredby USEPA (Boice, 1993a), either Ontario sediment quality guidelines or sediment qualityguidelines from NOAA (1990) as well as those from Barrick and Seller (1989) were used for

ecological screening.

1.2.3 Summary

In summary, this report contains quantitative evaluations tor exposures associated with thefollowing environmental media:

• Site surface soil and leachate seep soil:

• Surface water;

• Surface water sediments;



• Soil gas;

• Groundwater — shallow flow system; and

• Groundwater — outwash sand and gravel flow system.

It is understood that, in the process of refining the baseline risk assessment model during thecourse of regulatory agency review, deletion or addition of certain pathways or COPCs mayoccur. The results of the risk modeling, for example, could be used as a further screeningcriterion to select exposure pathways of likely concern that could be subjected to stochasticmodeling.

1.3 Human Health Evaluation

1.3.1 Analysis

The analysis phase of the stochastic human health evaluation consisted of two subphases:

• An exposure assessment; and

• A toxicity assessment.

The stochastic risk assessment was conducted using the same exposure algorithms as used in thedeterministic. These equations are outlined below and the parameter values and assumption madefor these parameter values and for the distributions for each of these parameter values is detailedin Enclosure C. The toxicity assessment used in the deterministic risk assessment was also usedfor the stochastic analyses. However, as described in Enclosure D, for some chemicals for whichthe data were available, a distribution of values for SFs and RfDs were developed and used inthe stochastic analysis as one more input variable. The purpose of the analysis phase is toidentify toxicity factors and exposure equations to be used in the assessment and to documentassumptions for each of the independent variables (input parameters) in these equations. Thetoxicity factors and exposure equations used in the assessment are presented in the followingsubsections. Supporting documentation for all assumptions made can be found Enclosures C andD.



1.3.1.1 Exposure Assessment

Three scenarios are identified in Section 1.2.2 for which 12 exposure pathways are identified anddocumented in Enclosure C to allow for quantitative evaluation:

• Adjacent Residential Scenario — assuming access restrictions- and institutionalcontrols are not effective and no groundwater usage occurs.

Ingestion pathwayssoil and leachate seep soilsurface watersediment

Dermal contact pathwayssoil and leachate seep soilsurface watersediment

Inhalation pathwaysoil gas

• Site Occupational Scenario — Current and Future

Ingestion pathwaysoil and leachate seep soil

Dermal contact pathwaysoil and leachate seep soil

• Future Adjacent Residential Groundwater Use Scenario —

Ingestion pathway

Dermal contact pathway

Inhalation pathway

Applicable equations for the calculation of carcinogenic and noncarcinogenic doses of themedium-specific COPCs for the 12 exposure pathways are:

Soil Ingestion Doses —

DC«, Dn...«. = IngR.xC.xEF0xFa.xCFxEDxBF0xUCF raxBW'xAT1 (3-1)



Surface Water Ingestion Doses —

DC..*.*, Da-.w.in, = IngR,xFw wxEvDwxC s wxEFwxEDxBW- |xAT' (3-2)

Sediment Ingestion Doses —

DC.*.,, Dn>i4Unf = IngR I ( ixC ldxFwa.wxEFwxEDxBF<>xUCFmxBW-1AT1 (3-3)

Soil Dermal Contact Doses —

Dc,.idc, DBJiin, = AdF.xC ixEF<(xCFxEDxET..dcxFaixSAxBFd

x UCFm x BW-' x AT1 x ADJ. v'(3-*)

Surface Water Dermal Contact Doses —

DC^JC, D,,.,̂ = DAnxEvDwxEFwxEDxSAxBW lxAT ! (3-5)

Sediment Dermal Contact Doses —

DC.*,*, D^.^ = AdFM,xC r ixEvDwxEFwxEDxET..dcxFMxSAxBFdxUCFm

xBW-'xAT'xADJ.^1

(3-6)Soil Gas Inhalation Doses —

DejMh, Dnj|iiBil = C. |xkxP.xAxEF ixEDx^1xL-1xQb- |xAT l (3-7)

Groundwater Ingestion Doses —

Shallow Groundwater Flow System:

D..,.̂ D .̂̂ = IngR^xC^F^xEF^EDxBW-'xAT' (3-8)

tDA for organics derived using Equations C-16 to C-25.



Outwash Sand and Gravel Groundwater Flow System:

De.rrt.ta,, D^.^ = InglCxC^F^xEF.xEDxBW'xAT' (3-9)

Groundwater Dermal Contact Doses —


Dc.gwi.dc, Dn<|wMc = DA txEvDbxEF ixEDxSAbxBW'xAT-'xBF1 ;1 (3-10)

Qutwash Sand and Gravel Groundwater Flow System:

= DA txEvDbxEF ixEDxSAbxBW lxAT'xBF0-1 (3-11)

Groundwater Inhalation Doses —


DC.̂ , D^,^ = C^xVFxEFiXEDxUCF.xET^xAT'xET^,™1 (3-12)

Qutwash Sand and Gravel Groundwater Flow System:

^xVFxEFiXEDxUCF.xET^xAT'xET^;1 (3-13)

Occupational Soil Ingestion Doses —

D,,.*, D^ = IngRMxC.xFM .wxEFwxEDwxBF0xUCFmxCFxBWw1xAT-' (3-14)

Occupational Soil Dermal Contact Doses —

DC...*, Dn..iiBI = AdF.,wxC.xEFwxEDwxSAwxBF (1xUCFmxETwxCFxBWw1

xAT'xET^;1 (3-15)

The dependent variables (output parameters) in Equations 3-1 - 3-15 are represented as D x y i ,where: x indicates either a carcinogenic (c) or noncarcinogenic (n) dose; y indicates the



environmental medium (s represents surface soils, sw surface water, sd sediments, sg soil gas,gw groundwater); and, z indicates the exposure route (ing represents ingestion, dc dermalcontact, and inn inhalation).

The variables (input parameters) in the exposure equations, in the order that they first appear,are:

• IngR, — soil ingestion rate;

• C. — chemical concentration in surface soil (for each of eight COPCs insurface soils);

• EFa — outdoor exposure frequency;

• FM — fraction of exposure on affected soils;

• CF — weighted climate factor;

• ED — exposure duration;

• BF0 — contaminant-specific oral bioavailability factor (for each of the 24COPCs);

• UCFB — mass unit conversion factor;

• BW — body weight;

• AT — averaging time;

• IngR, — incidental ingestion rate of water while wading;

• F»««, — fraction of wading exposure in affected surface waters;

• EvDw — duration of a wading event;

• C.W — chemical concentration in surface water (for each of ten COPCs insurface water);

• EFW — wading exposure frequency;

— sediment ingestion rate;

Cu — chemical concentration in sediment (for each of nine COPCs insediments);

ETi>dc — duration of exposure to sediment;

ADJ, fc — adjustment for the duration of the study upon which bioavailabilityfrom soil is based;



• AdF, — soil skin adherence factor;

• SA — skin surface area;

• BFd — contaminant-specific bioavailability factor for dermal contact (for eachoflOCOPCs);

• Kp — contaminant-specific permeability constant (aqueous bioavailabilityfactor) for dermal contact (for each of the 17 COPCs);

• MW — molecular weight;

• AdF,,, — sediment skin adherence factor;

• C,, — chemical concentration in landfill soil gas (for each of five COPCs insoil gas);

• k — permeability of soil to soil gas;

• P, — dynamic landfill gas pressure;

• Pb - dynamic pressure at landfill boundary

• A — effective contaminant flux area;

• EFj — indoor exposure frequency;

• /i — dynamic viscosity of soil gas;

• L — distance from landfill to building;

• Qb — building ventilation rate;

— tap-water ingestion rate;

Cgwi — chemical concentration in the shallow groundwater flow system (foreach of eight COPCs in shallow groundwater);

Cf»2 — chemical concentration in the outwash sand and gravel groundwaterflow system (for each of five COPCs in outwash sand and gravelgroundwater);

fc — duration of a bathing event;

SAb — surface area of skin exposed while bathing;

VF — volatilization factor;

UCFV — volume unit conversion factor;

EFW — Site work exposure frequency;



• ET|w.i* — exposure time for inhalation of groundwater;

• ETfWiCWlv — conversion factor

• IngRo, — soil ingestion rate for Site workers;

• BW0 - body weight for Site workers;

• EDW — occupational exposure duration;

• SAW — skin surface area for Site workers;

• FM>W — fraction of worker exposure on affected soil;

• AdF1?w — soil skin adherence factor for workers;

• ETW — exposure time for workers; and

• ETwlc0ilv — conversion factor.

The stochastic distributions and the assumptions for each of these exposure variables anddistributions for those variables are defined with supporting rationale in Enclosure C. As part

of the stochastic analyses, variables that are naturally correlated are not treated asindependent. For example, ingestion rates (i.e., food, water, and soil) typically are related toage or body weight. Dependent variables were directly correlated together within thestochastic analysis to prevent improbable scenarios from being chosen during randomsampling. In this assessment, the results of the 50th, 90th, 95th, and 99th percentile estimatesof incremental lifetime cancer risk or hazard index are given in Enclosure E.

The Site-sampling data used in this evaluation are presented in Enclosure A. A modificationof the log normal distribution (the p-log normal) derived using the Maximum LikelihoodMethod (Crump 1993), as described in Enclosure C. The concentrations for the COPCs in

surface soils, surface water, sediments, soil gas, shallow groundwater, and outwash sand andgravel groundwater are presented in tables in Enclosure C. In cases where a contaminant wasnot detected in all samples, a statistical test, termed the Maximum Likelihood Approach, wasused to estimate Site concentrations (Crump 1993). This method is described in Enclosure C.Duplicate or split samples were averaged first. Then the one value was used to determine theaverage and upper bound concentrations. Vinyl chloride was not detected in soil gas;however, USEPA (Boice, 1993a) has required that vinyl chloride be included at one-half thedetection limit, even though not detected.



1.3.1.2 Toxicitv Assessment

The purpose of the toxicity assessment is to identify the potential adverse effects that could beassociated with exposure to Site-related substances and to evaluate, using numerical toxicityvalues, the likelihood that these adverse effects may occur. The toxicity assessment for thisrisk assessment is conducted in accordance with USEPA (1989).

In general, toxicity assessment is conducted in two stages: hazard identification and dose-response evaluation. Hazard identification is the determination of whether the exposure to anagent could result in an increase in the incidence of adverse health effects, while dose-response evaluation is the process of quantitatively characterizing the relationship between thedose of a toxic substance and the corresponding incidence of deleterious effects in an exposedpopulation (USEPA, 1989). Toxicity information on chemicals is available in the Agency forToxic Substances Disease Registry lexicological profiles, the scientific literature, HealthEffects Assessment Summary Tables (USEPA, 1992b), and USEPA's on-line database,Integrated Risk Information System (USEPA, 1993). The relevant toxicity for eachcontaminant is presented in Enclosure D along with appropriate toxicity criteria values, asdiscussed in the following sections.

1.3.1.2.1 Toxicitv Information for Carcinogenic Effects

The potential for human carcinogenic effects is evaluated based on the contaminant-specificSF and the weight-of-evidence classification of the USEPA. The SF is the toxicity value thatquantitatively defines the dose-response relationship of a known or suspected carcinogen. TheSF is an estimate of an upper bound lifetime probability of an individual developing cancerfollowing exposure to a potential cancer causing agent for the lifetime of the individual, SFsfor chemicals are generally expressed as the 95% upper confidence limit of the slope of thedose-response curve and are derived by assuming low-dose linearity and applying a computermodel to extrapolate from the relatively high doses administered to animals (or the exposuresobserved in epidemiological studies) to the lower environmental exposure levels that generallyoccur in humans. The USEPA has developed SFs for chemical classified as carcinogens,based on the premise that there is no threshold, i.e., level of exposure below which there isno risk of a carcinogenic effect.



Because the SF is generally the 95% upper confidence limit of the probability of a responseper unit intake of a chemical over a lifetime exposure, the use of such SFs, thus, results in aconservative (i.e., upper bound) estimate of potential cancer risk. That is, the true risk tohumans is not likely to exceed the upper bound estimate, but could be lower and may even bezero. Further, because the dose-response curve is assumed to be linear in the low-doseregion, the accuracy of the SF may be limited if this region should, in reality^ exhibitnonlinearity.

The multistage model was used to develop SFs that give the Maximum Likelihood Estimate(MLE) of the SF and the 95% upper confidence limit on that MLE. Simply stated, thisrepresents, with 95% certainty, the largest value for the linear term, i.e, slope, in themultistage model that is consistent with the data. However, other confidence bounds on theMLE can be generated, i.e., the 90% or the 99%. Similarly, the 95% lower bound on theMLE can be generated by the multistage model, that estimates, with 95% certainty or anyother confidence bound, the smallest value for the linear term that is consistent with the data.

Essentially, based on the same bioassay data, for those chemicals with animal bioassay datasuitable for analysis, a distribution of SF was generated that is used as an input variable in thestochastic analysis. The method for generating these distributions is discussed briefly inEnclosure D.

Table D-l summarizes the carcinogenic toxicity values (i.e., SFs), the corresponding weight-of-evidence classifications, and the types of cancer for the Group A COPCs at the Site.Additional discussion on each COPCs that have been classified as carcinogens is provided inEnclosure D.

1.3.1.2.2 Toxicitv Information for Noncarcinogenic Effects

Systemic toxic effects other than cancer can be associated with exposures to chemicals. TheRfDs or RfCs are the toxicity values that are used to evaluate the potential of developingno near ci no genie effects as a result of exposure to potentially toxic chemicals. The RfD/RfChave been developed on the premise that protective mechanisms exist that must be overcomebefore an appreciable risk of adverse health effects is manifested during a defined exposure



period. That is. it is assumed that there is a threshold dose which must be exceeded beforeadverse effects can occur.

Chemicals classified as carcinogens may also produce other systemic effects. These chemicalswere also evaluated for potential noncarcinogenic toxic effects and were included in thedetermination of chronic toxicity hazard indices which characterize noncancer' hazards.Carcinogenic effects, however, are usually manifested at levels that are significantly lowerthan those associated with systemic toxic effects; thus, cancer is usually the predominantadverse effect for contaminants that may elicit carcinogenic as well as noncarcinogenicresponses.

In a method similar to that used for chemicals classified as carcinogens, distributions of RfDswere generated for those chemicals with appropriate data for use as input variables into the

stochastic analysis. This method is also discussed in Enclosure D.

Table D-l in Enclosure D summarizes the noncarcinogenic toxicity values (i.e., RfDs/RfCs)and the corresponding critical effects for the COPCs at the Site. Additional information onthe noncarcinogenic effects for each contaminant of potential concern is presented in thetoxicity profiles in Enclosure D.

1.3.1.2.3 Adjustment of Toxicitv Factors

As stated in USEPA (1989), for purposes of conducting risk assessment for potential exposureto contaminants at hazardous waste sites, it is necessary to adjust an oral toxicity factor (i.e.,RfD or SF) from an administered to an absorbed dose. Because most of the toxicity valuesfor the COPCs at the Site are expressed as orally administered doses (i.e., intake-based), it isnecessary to adjust both the RfDs and SFs for these substances in estimating exposure on anabsorbed-dose basis.

As noted in the Toxicity Assessment (Enclosure D), the oral RfDs and oral SFs for eachcontaminant of potential concern are modified according to the following equations:



ERfD0 = RfD0xBF,,, (3-16)

ESF0 = SF0/BFu.d (3-17)

where:

• ERfD, is the effective absorbed-dose oral RfD for each chemical;• RfD0 is the oral RfD for each chemical;• BF0-, is the absolute oral bioa vail ability factor for each chemical;• ESF0 is the effective absorbed-dose oral SF for chemical; and,• SF0 is the oral SF for each chemical.

The inhalation RfDs and inhalation SFs are modified as follows:

ERfD; = RfDiXBF; (3-18)

ESF; = SF/BFi (3-19)

where each variable is as defined above except that i denotes a factor specific to the inhalationexposure route. The BF; values for each of the gaseous COPCs identified in soil gas areconservatively assumed to be 1 .00.

In this stochastic analysis, distributions of values for the parameter, BFOJ, for each COPC wascreated and used as another input distribution. Table C-2 presents the BFM values for thechemicals for which toxicity factors are based on oral ingestion studies.

1.3.2 Stochastic Risk Characterization

Risk characterization combines estimates of exposure with toxicity data to develop estimatesof the probability of the occurrence of an adverse effect under the specified conditions ofexposure. The risk characterization was divided into three subphases:

• Risk estimation;

• Risk description; and,

• Uncertainty analysis.



Risk estimation is accomplished by combining the toxicity factors and exposure assessmentequations to calculate estimates of risks. Estimates of carcinogenic risks are reported asincremental (above background) lifetime cancer incidence risks, or ILCRs, andnoncarcinogenic risks are reported as path way -specific hazard quotients, or HQs or HI. whichis the sum of pathway-specific HQs. Risk description entails several discussions, includingthe relative contributions of individual exposure pathways to the total risk. the. significance ofthe risk estimates relative to action levels set forth in USEPA policy (i.e., an ILCR above 10*to 10"4 and an HI or HQ above 1.0). The uncertainty analysis describes and quantifies, wherepossible, the impact of data, assumptions, and parameter values on estimates of risk.

1.3.2.1 Stochastic Risk Estimation

In the deterministic baseline risk assessment, estimates of incremental lifetime cancer risk arecalculated by multiplying the dose by the SF.

For estimates of noncarcinogenicity hazard indices, the dose is divided by the RfD or RfC.Operationally in the stochastic analysis, a distribution tor each parameter value including,when available, distributions for SFs or RfD/RfCs, is randomly sampled and a distribution ofrisk estimates is created. However, the applicable equations for the risk estimation are:

Soil Ingestion Risks —ILCR,.* = ESF0xDc,.mg (3-20)

(3-21)

Surface Water Ingestion Risks —

= ESF.xD,.^ (3-22)

= Dnw>in,/ERfD0 (3-23)

Sediment Ingestion Risks —

^ = ESF.xD^ (3-24)



,^ = D.^/ERfD. (3-25)

Soil Dermal Contact Risks —

ILCR..* = ESF0xDe.,dc (3-26)

HQ..4, = D^/ERfD, (3-27)

Surface Water Dermal Contact Risks —

= ESF.xD,^ (3-28)

= D^/ERfD. (3-29)

Sediment Dermal Contact Risks —

* = ESF.xD^.* (3-30)

(3-31)

Soil Gas Inhalation Risks —

(3-32)

(3-33)

Groundwater Ingestion Risks —

Shallow Groundwater Flow Svstem

- ESF.xDe^lJH (3-34)

Dwhillg/ERfD0 (3-35)

Outwash Sand and Gravel Groundwater Flow Svstem

=ESF0xDc.8W3.ing (3-36)

= D..iB2.ili/ERfDa (3-37)

Groundwater Dermal Contact Risks —



Shallow Groundwater Flow System

rt^ = ESF0xD rgwl.dc (3-38)

,.*, = D.^/ERrD. (3-39)

Outwash Sand and Gravel Groundwater Flow System

= ESF.xD,.,^ (3-40)

= 0,,^/ERfD. (3-41)

Groundwater Inhalation Risks —


ILCR^,*, = ESFiXD^,^ (3-42)

Qutwash Sand and Gravel Groundwater Flow System

(3-43)

Occupational Soil Ingestion Risks —

= ESF.xD,...,.. (3-44)

= D^/ERfD. (3-45)

Occupational Soil Dermal Contact Risks —

= ESF^D,.^ (3-46)

..^ = D^/ERfD, (3-47)

The effective toxicity factors are as defined in equations 3-16 - 3-19; and the absorbed dosesare as defined for Equations 3-1 - 3-15; the subscripts identifying each of the abovedependent risk variables have the same meaning as those used to identify doses.

The pathway totals for estimated lifetime extra cancer risks for each scenario are calculatedthe same as in the deterministic baseline risk assessment tor the Site (1CF Kaiser, 1994) by



summing the ILCRs for each pathway within each scenario, and by summing the HQs forCOPCs having similar systemic effects for noncancer risks {as a first approximation, allCOPCs are assumed to have additive effects).

The estimated total extra lifetime cancer risk is shown in the following equations:

Adjacent Current Residential Scenario —

Future Groundwater Use Scenario —


ILCRp,, = ILCR^+ILCR^+ILCR^ (3-49)


(3-50)

Adjacent Future Residential Scenario —

=ILCRm + (ILCR^, or ILCF^ (3-51)

Site Occupational Scenario —

ILCR^ = ILCR^+ILCR.^ (3-52)

The calculations for noncancer risks are shown in the following equations, which conservativelyassume (as a first approximation) that all COPCs for a given scenario have additive toxic effects:

Adjacent Residential Scenario —

_jc (3-53)

Future Groundwater Use Scenario —


HQp*i = Hiding + HIgwlde+Hlgwl inh (3-54)




jj + HI^id, (3-56)

Future Residential Scenario —

HI^ =HIm + (HQ^ or HQ^J - (3-57)

Site Occupational Scenario —

HIW = HI^ + HU (3-58)

The total carcinogenic and noncarcinogenic risks associated with the Adjacent Residential, SiteOccupational, and Future Residential Scenarios are presented in Tables 1 to 12.

1.3.2.2 Stochastic Risfr Pescriptton

As with the deterministic risk assessment, the risk description for the Site is provided below intwo parts. First, the relative contributions of the various exposure pathways are analyzed foreach exposure scenario. Second, the relative contributions of each contaminant are analyzed foreach exposure scenario. The estimated risks by individual pathway are given in Enclosure E.

1.3.2.2.1 Exposure Pathway Contribution Analysis

The estimated risks are summed for each chemical in a pathway across each pathway evaluated.As such, they are conservative for two reasons. First, the estimated risks for each chemical ina pathway are based on upper bound assumptions regarding exposure (i.e., the RME individual).Second, the risks compound this conservatism by assuming that an individual is exposed to allpathways. The summation of risks does not take into account the likelihood of use tor apathway. For example, as discussed in the RI (Colder, 1994), the nature of the formations forthe two groundwater flow systems makes it technically unlikely that this ground water would beused as a water supply. Consequently, if the likelihood of use of the groundwater is virtuallyzero, any risks associated with the use of this groundwater would also be virtually zero.



1.3.2.2.1.1 Description of Incremental Lifetime Cancer Risk Estimates

Adjacent Residential Receptor. The same pathways evaluated deterministically were alsoevaluated stochastically. The stochastic estimates of incremental lifetime cancer risk for exposurepathways assessed for the Adjacent Residential Receptor, who represents the RME receptor undercurrent potential use conditions, are listed in Table 1. As defined by USEPA (Boice, 1993), theRME for the Adjacent Residential Receptor assumes there are no access restrictions orinstitutional controls and no groundwater usage occurs. The RME is assumed to live adjacentto the Site from early childhood, continuing for up to 30 years, and is also assumed to go toschool adjacent to the Site. As such, the RME is conservatively assumed to be exposed to Sitecontaminants through all exposure pathways evaluated with the exception of groundwater (whichis a component of the hypothetical future use scenario). The uncertainty associated with theseassumptions is discussed in Section 1.3.2.3. Estimates of exposure were based on thedistributions of parameter values described in Enclosure C and D for COPCs in eachenvironmental media. The contribution of individual COPCs to the estimated risk for any

pathway are given in Enclosure E.

Incremental lifetime cancer risk for each of the pathways in the residential scenario is below the10* risk level. Estimates of incremental lifetime cancer risk for exposure by way of all pathwaysare also less than the 10* risk level. The estimated risk to the Adjacent Residential Receptor is9.1 x 10"* in the 50th percentile and 5.8 x 10"7 for the 95th percentile. The majority of that riskwas due to estimates based on direct contact with or ingestion of surface soil/leachate seep soil,which accounted for approximately 53% of the estimated risks, while the soil gas inhalation

pathway represented 30% of the total. All other pathways contributed less than 20% to the total.

These stochastic estimates can be compared to the deterministic estimate of lifetime cancer riskderived for the same chemicals and pathways. The average deterministic estimate was 5.9 x 10*compared to the stochastic estimate at the 50th percentile which was 9.1 x 109. The upper bounddeterministic estimate was 6.0 xlO"3, while the estimated risk at the 95th percentile was twoorders of magnitude lower at 5.8x 10"7. The deterministic estimate was closer to the 99.9thpercentile than the presumed "95% upper bound".



It is interesting to note that of the estimated risk for the inhalation of soil gas pathway, v inyl

chloride contributed 63% of the total estimate (at the 95th percentile distribution) for thatpathway. Vinyl chloride was not detected in the media; however, as instructed by the USEPA(Boice. 1993a), vinyl chloride was added and assumed to have been detected at one-half the

detection limit.

Future Residential Scenario. As defined in the deterministic assessment, the Future ResidentialScenario assumes access restrictions and institutional controls are not effective and groundwaterusage occurs. This receptor is defined as an adjacent resident who is assumed to have thepotential to be exposed to surface soil/leachate seep soil, surface water, sediment, and soil gas,as described above. In addition, future groundwater usage for household and drinking waterpurposes was assumed for this assessment, even though all residents of the area are served bymunicipal water sources, which derives their water from Lake Michigan. If the future residentscontinue to receive their water supply from a municipal source, then the major contributors torisk by these pathways are the same as those discussed in the previous Section for the currentAdjacent Residential Receptor who is assumed to be exposed to Site contaminants to the extentand manner described (i.e., no risks were greater than IxlO"*}.

However, as with the deterministic analysis, if the RME for Future Residential Receptor couldalso be assumed to derive all of their water source for drinking, bathing, etc.. from either theshallow or outwash groundwater, which is considered to be highly unlikely, both groundwaterpathways and Adjacent Residential Scenarios pathways could be considered together for the RME.as required by USEPA (Boice, 1993a). Both filtered and unfiltered groundwater samples weretaken for each aquifer; estimated exposure and risks were derived for exposure by way of

ingestion and dermal contact with groundwater, and inhalation of volatiles released fromgroundwater during household use. Therefore, the future RME consists of five differentscenarios depending on the source of groundwater and filtration of groundwater. The stochasticestimate of incremental lifetime cancer risks by pathway and by source/type (filtered orunfiltered) of groundwater for the 50th, 90th, 95th, and 99th percentiles are listed in Table 2afor shallow groundwater and Table 2b for the lower outwash groundwater.



Tables 2a and 2b present the estimated lifetime risks to a hypothetical future receptor designatedthe RME and detail the contribution of residential use of groundwater to the total incrementallifetime cancer risk. As a result of the statistical comparisons to background, only organicchemicals remained in the analysis of estimated lifetime cancer risks. The concentrations of theseorganic constituents were the same in both filtered and unfiltered samples. Hence, the estimatedincremental lifetime cancer risk to the RME from a hypothetical future groundwater use scenariois the same for filtered or unfiltered groundwater.

When the RME is assumed to include the pathways under the current Adjacent Residential

Scenario and a Future Use Groundwater Scenario, the major contributors to the total incrementallifetime risk estimated are the groundwater use pathways, with ingestion of groundwater as theprimary contributor (61%) to total estimated risks. Inhalation and dermal contact with shallowgroundwater during residential use contributed 9% and 16% to the total RME estimated risks at

'N r̂the 95th percentile. Of total estimated risk, groundwater pathways contributed 6.5xl07 and3.5x10"* for the 50th and 95th percentiles. With the ingestion pathway for the shallow aquifer,vinyl chloride contributed 80% of the total incremental estimated risk at the 95th percentile. Forthat combined scenario (all nongroundwater pathways and all groundwater pathways) with shallowgroundwater as the source, the total estimated incremental lifetime cancer risk was 5.7 x 107 and4.1 x 10"* for the 50th and 95th percentiles, respectively (Table 2a). In the deterministic analysis,the estimated risks for all groundwater and nongroundwater for the shallow aquifer were 7.6x 10"6

in the average and 7.1xlO"3 in the upper bound case. The deterministic upper bound estimatedrisk corresponds to an estimated risk greater than that estimated tor the 99th percentile in thestochastic analysis.

If the lower outwash aquifer were part of the future RME scenario, the total incremental lifetimerisk would be 2.6xlO"7 and 2.1 x lO^at the 50th and 95th percentile for all nongroundwater andgroundwater pathways combined (Table 2b). The contribution of the groundwater pathways alonerepresents approximately 72% of the total estimated risks for the RME tor the 95th percentile and95% of the total at the 50th percentile (Table 2b). However, the estimated incremental cancerrisk for each lower outwash groundwater pathway individually was less than 1 x 10* at the 95thpercentile. The contribution to risk from lower outwash groundwater ingestion (at the 95thpercentile) was 1.6xlO"7 compared to 1.8x10* for the deterministic assessment. Similarly,



stochastic estimates for all lower outwash groundwater pathways were 1.5x10"* at the 95thpercentile compared to the deterministic estimate of 7.5 x 10"", which is larger than the stochasticestimate at the 99th percentile.

Site Occupational Scenario. The Occupational Worker Receptor was defined the same in thestochastic analysis as the deterministic (Table 3). The worker was assumed to perform work-

related activities on the Site for up to 8 hours per day up to 25 years. Exposure was assumedto occur through incidental ingestion of soil or dermal contact with soil. The distribution ofvalues tor the exposure parameters used in assessing risk for this receptor are described inEnclosure C.

Stochastic estimates of the incremental lifetime cancer risk for the occupational scenario pathwayswere all less than the 10"* risk level and were 2.6x10"" and 9.7x 107 for the 50th and 95thpercentile, respectively (Table 3). These stochastic estimates can be compared to the estimatedrisks using deterministic methods. With the deterministic analysis, estimated risks were 2.4 x 10"*and 5.6x 10"5 in the average and upper bound cases, both of which are higher than the stochasticestimates for the 95th percentile. The upper bound deterministic estimate corresponds moreclosely to the 99.9th percentile of the stochastic analysis.

1.3.2.2.1.2 Description of Noncancer Hazard Indices

The noncarcinogenie exposure pathways were assessed stochastically for the three exposurescenarios listed below. Hazard Indices were estimated based on chronic exposure to a child, asinstructed by USEPA (Boice, 1993a). This results in considerably higher estimates of intake thanthat estimated for an adult and consequently results in higher estimates of the Hazard Indices.

Adjacent Residential Scenario. The HI^ for each pathway and chemical evaluated are listed in

Table 4. The HI^, is less than 1.0 for any scenario, and the sum across pathways is also lessthan 1.0.



Future Residential Scenario. The HI^ for each pathway and chemical evaluated are listed inTable 5. The Hl^f is less than 1.0 for any scenario, and the sum across pathways is also less

than 1.0.

Site Occupational Scenario. The HI^ for each pathway and chemical evaluated are listed inTable 6. The HI,^ is less than 1.0 for any scenario, and the sum across pathways is also lessthan 1.0.

1.3.2.2.2 Contaminant Contribution Analysis

The carcinogenic contaminants (including both known and suspected human carcinogens) assessedunder the three exposure scenarios are listed in Tables 7-12.

1.3.2.2.2.1 Description of Incremental Lifetime Cancer Risk Estimates

Adjacent Residential Scenario . None of the COPCs had estimated risks greater than 1 x 1C* ateither the 50th or 95th percentile of the distribution and the total estimated risks across allpathways was also less than 1 x 10* (Table 7). The sum total contribution for all COPCs in thescenario was 5.8xlO*7 (95th percentile). The estimated risk of 6.0xlO"3 in the deterministicevaluation is higher than that estimated at the 95th or 99th percentile of the stochastic analysis.In the deterministic assessment, Aroclor 1242 contributed an estimated risk of 4.7 x 10"5, whichis 77% of the total path* /y risk. In the stochastic analysis, Aroclor-1242 was still the majorcontributor (3.7x 10"7); however, this risk is not considered to be significant.

Future Residential Scenario. The contaminant contribution under the Future Adjacent Residential

Scenario is listed in Tables 8a and 8b for the shallow groundwater and the lower outwashgroundwater, respectively. The addition of the groundwater pathways to the nongroundwaterpathways (as discussed under the Current Adjacent Residential Receptor) for the stochasticanalysis did alter the risk estimates. With the shallow groundwater, vinyl chloride was the majorcontributor to the RME under the assumption that adjacent residents receive their water torresidential use from the shallow groundwater. Vinyl chloride contributed an animated risk of2.5x 10"* to the estimated risk of 4.1x10* for the total pathway contribution (both groundwater



and nongroundwater scenarios). Bis(2-ethylhexyl )phthalate contributed approximately 16% to the

total risk. Benzene contributed approximately 14% to the total pathway estimated risks.

For the lower outwash groundwater, all of the estimated risks tor each COPCs individually wereless than 1 x 10"6; however, the sum total of the individual COCPs tor all pathways was 2.1 x 10~6.Benzene was the major contributor to the total estimated lifetime risk contribating an estimatedrisk of 9.4xlO'7 (44%).

Site Occupational Scenario. In the stochastic analysis of the risks to workers exposed to Site

contaminants by way of incidental ingestion and dermal contact with soil/leachate soil seep, allof the individual chemicals contribution was less than 1 x 10"e, as was the total of all chemicals

for this scenario (Table 9).



1.3.2.2.2.2 Description of Hazard Indices

The noncarcinogenic exposure pathways assessed stochastically under the three exposure scenariosare listed below in the same manner (conservatively assuming toxic-etfects additivity as a firstapproximation):

Adjacent Residential Scenario. The Hl^ for each chemical evaluated across pathways is listedin Table 10. The HI^ is less than 1.0 for any chemical, and the sum across chemicals is also

less than 1.0.

Future Groundwater Use Scenario. The HI^ for each chemical evaluated across pathways islisted in Table 11. The Hl^.r is less than 1.0 for any chemical, and the sum across chemicalsis also less than 1.0.

Site Occupational Scenario. The HI^ for each chemical evaluated across pathways is listed inTable 12. The HI^ is less than 1.0 for any chemical, and the sum across chemicals is also lessthan 1.0

1.3.2.3 Uncertainty Analysis

Quantitative analysis of uncertainty is not possible in a purely deterministic risk assessment. Astochastic assessment can allow for quantification of the uncertainty and can be used to determinethose parameter values that are contributing significantly to the estimated risk. However,uncertainties still remain, some of which are similar to as those encountered in the deterministicanalyses as discussed briefly in the r Mowing sections.

1.3.2.3.1 Uncertainties Related to the Toxicity Assessment

Uncertainty is associated with the toxicity values and toxicity information available to assesspotential adverse effects. For this Site, there is a possibility of overestimating health risks orhazards for a number of reasons which are discussed in the following sections. Theseuncertainties are less problematic when a stochastic analysis is conducted.



One of the major contributors to uncertainty is the correctness of the toxicity values used. Theassumptions utilized by the USEPA in the dose-response extrapolation model for carcinogens areconservative. That is, the determination of carcinogenic potency for COPCs is based on a 95%upper bound limit, and assumes the following: (1) the extrapolation of data from high-dose

exposure region in human and animal studies to low-dose exposure region of the generalpopulation is assumed to be linear and not to have a threshold; (2) an interspecies (i.e., animalto man) correlation, based on body surface area; and (3) the conditional probability thatdemonstrated cancer incidence in animal studies will also have similar occurrences in potentiallyexposed humans.

Two of the main areas of uncertainty in toxicity assessment involve the selection of theappropriate animal data upon which the estimate of human risk is based (animal to humanextrapolation) and the characterization of the shape of the dose-response curve in the low doseregion (high-to-low dose extrapolation). USEPA guidelines state that in the selection of data touse quantitatively, that selection should maximize the biological correlations between animals andhumans (USEPA 1986). The selection of the data upon which to base the cancer SF for PCBsillustrates this uncertainty, PCBs are a family of 209 compounds that differ in the position andnumber of chlorines on biphenyl rings and toxicity varies widely depending on the number and

position of chlorines. Aroclor-1260, comprised of approximately 60% chlorine does not containthe identical congeners in the identical proportions as those found in Aroclor-1242 or -1248 (Safe1993). The potency of Aroclor-1260 is based on experimental data that are not suitable for usein quantitative risk assessment for a number of reasons, the most important of which was that theanimals had part of their livers surgerically removed to facilitate the development of tumors withapplication of PCBs (Crump and Shipp 1990). The SF derived from this study was

approximately twice that based on another bioassay. Therefore, the potency factor for Aroclor-1260 is in itself conservative. Further, all other PCBs are conservatively assumed to be as toxic

as Aroclor-1260, as required by USEPA (IRIS 1993), even when scientific, peer-reviewed dataindicate otherwise. It is likely that Aroclor-1242 and -1248 are less potent than Aroclor-1260by an order of magnitude (Safe, 1993; Crump and Shipp, 1990).

Another major contributor to uncertainty is the assumption regarding extrapolation from high tolow doses. Use of a linear, nonthreshold approach is consistent with a presumed mechanism of



action for cancer development. However, considerable experimental evidence suggests that themechanism of action of certain chemicals, such as trichloroethylene or PCBs, may be due topromotional mechanisms that are not linear at low doses. For example, the SFs and weight-of-evidence classifications for tetrachloroethene, trichioroethene, and vinyl chloride are under review

by USEPA because the pharmacokinetics of these chemicals in animal models and in humans isunder consideration.

In a stochastic analysis in which a distribution of SFs has been generated based on the animaldata, there is less uncertainty than relying only on the 95% upper confidence limit on the MLE.However, uncertainties still remain in the selection of the appropriate data to use and method forextrapolating across species. Another example of uncertainty is the use of the most appropriatedata is demonstrated in the derivation of the SF for beryllium.

The bioavailability of the COPCs from the dermal exposure route through water use or contactwith soil is uncertain for many chemicals. SFs and RfDs are adjusted, as discussed in Enclosure

C, to evaluate the dermal exposure routes usually resulting in more conservative SFs and RfDs.The supporting data on the absorption efficiency of the COPCs is generally derived from animaldata that may not necessarily be representative of absorption efficiency in humans. Absorptionof contaminants in soil is generally diminished due to the matrix effect of the soil. This isparticularly true for those inorganics which may be a component of the mineral structure of thesoil and, thus, may not be available for uptake. With the stochastic analysis, the uncertaintymay be reduced because a distribution of bioavailabil ity factors would be used rather than a singlepoint estimate.

According to USEPA guidelines for risk assessment of chemical mixtures (USEPA, 1986c), inthe absence of specific toxicity data concerning the synergism. antagonism, or potentiation ofeffects, the potential health hazards and risks associated with exposure to chemical mixtures areassumed to be additive. The assumption of additivity tor the COPCs in the environmental mediamay overstate the actual total chronic toxicity because the major contributors may have entirelydifferent disease mechanisms, and may also act on unassociated physiological systems.



1.3.2.3.2 Uncertainties Related to Estimates of Exposure Point Concentrations

When evaluating the potential risks due to chemical exposure at a Site, there are two mainconsiderations both of which contribute to the uncertainty in estimates of risk. One factor is theselection of the COPCs, thai is, those constituents that may be clearly identified to have elevated

concentrations as a result of Site-related activities. The second factor is the estimate of

concentrations of each constituent in the environmental media.

In this investigation, organic COPCs were evaluated even if present in a background sample. Allof the organic constituents that were detected at the Site were assumed to be COPCs. and wereretained in the investigation. No consideration was given to the contribution of other potential

sources of organic constituents (e.g., anthropogenic contributions from gasoline exhaust relativeto the levels of PAHs found at the Site) to estimates of risk.

The estimate of concentrations of each contaminant of potential concern is also uncertain. Manyof the constituents retained as COPCs, especially the organic constituents, are detected in onlya few of the samples collected, and in some cases in only one sample (see Enclosure A). In the

calculation of exposure point concentrations, constituents that are not detected in a sample areassumed to be present at one-half the SQL, when indeed the constituent may not be present at allin that sample. According to the USEPA, when the number of nondetects exceeds 10% to 15%of the total number of samples collected, the use of one-half of the SQL is not appropriatebecause it results in overestimates of the mean and UCL for a constituent (USEPA I992e).However, in the stochastic analysis, a statistical method, the Maximum Likelihood Approach(Crump 1993) was applied to the data. With this statistical technique, nondetects are not all

assigned to a certain value, such as one-half the detection l imi t . Rather all the data are used toestimate the most likely value for a nondetect assuming a log normal or weibull distribution.

Mean and 95% upper bound estimates as well as a distribution of values for use in stochasticmodeling is provided.

Exposure scenario parameter values selected add to the uncertainty. For example, thesoil/Ieachate seep soil scenario assumed a 30% contribution from seep soil, which is consideredan overestimate of the seep area. In addition, it is assumed for the RME that this receptor could



be exposed by way of all pathways. The more likely estimate of area occupied by seeps is 0.3%of the total area; approximately 10% of the Site by area is assumed to be seep if a 20-foot seepborder surrounded the Site (Colder. 1994b). Aroclor-1242 was detected in leachate seep but wasnot found in surface soil. If the percentage seep contribution was assumed to be 0.3% rather than30%. the estimated risks for exposure to Aroclor-1242 through the ingestion would decrease bya factor of approximately 100 from approximately 1x10"' to IxlO"7 .

Estimation of risks to the Adjacent Residential Receptor under current and future conditions wasbased on ingestion and contact with surface soil and leachate seep soil. It was assumed in thatno access restrictions or institutional controls were operative and that children and adults had freeaccess to the seep soil that is within the fenced area. To access the impact on risk estimates ofthe assumption of unrestricted access, an analysis was done that excluded seeps (numbers 1through 4) that are contained within the fenced area. Again assuming a leachate seep soil tosurface soil ratio of 30% to 70% and using seep samples 5 through 8, which are outside of thefenced area, estimated incremental lifetime cancer risks for ingestion of soil would beapproximately 3x10"*. The estimated risk for dermal contact with the soil was alsoapproximately 3 x 10*. The major contributors to this risk estimate are Aroclor-1248, which wasfound in a few soil samples, but not in any seep samples, and benzo(a)pyrene, which was foundin both seeps and surface soil. Benzo(a)pyrene and other PAHs are widely distributed in surfacesoils in urban environments due anthropogenic activities and could be present at the Site becauseof activities unrelated to the Site. This value is in contrast to the estimated risk of 1.5 x 1C5 forthe ingestion pathway and 4x 10* for the dermal contact pathway obtained when unrestrictedaccess is assumed.



1.4 Ecological Evaluation

The stochastic analysis and risk characterization phases of the ecological evaluation are presented

in this chapter. In Section 1.2.1, COPCs in surface water, surface water sediment, surface soil,and leachate soil were selected. In Section 1.2.2 the exposure pathways of concern were selectedfor terrestrial receptors (i.e., red-winged blackbird and mink) . The analysis phase, consisting

of terrestrial exposure assessments for red-winged blackbird, red-winged blackbird nestlings, and

mink, and an ecotoxicological assessment, is presented in Section 1.4.1. The riskcharacterization phase, consisting of risk estimation, an uncertainty analysis, and a description

of risks, is presented in Section 1.4.2.

This section presents a discussion of the stochastic (i.e., Monte Carlo) modeling analysis usedto calculate the probability distributions of potential ecological risks that may be associated withexposure to chemicals at the Site. The plant, insect (bird), Crustacea (mink), terrestrial animal(representing ingestion of small animals and rodents in the mink), incidental soil, and surfacewater ingestion pathways were analyzed using this stochastic approach to take advantage ofexposure data, demonstrate the variability in risks that may occur, and to show how thedeterministic cases (average and upper bound) relate to the full range of potential risks.

1.4.1 Analysis

The stochastic ecological analysis phase is presented in two pans: exposure assessment andecotoxicological assessment, in Sections 1.4.1.1 and 1.4.1.2. respectively. As with thedeterministic assessment, the purpose of the analysis phase was to identify exposure andecotoxicological equations to be used in the ecological assessment, and to document assumptionsfor each of the independent variables (input parameters) in these equations. Distributions ofvalues for most of the exposure parameters were determined and are reported in Enclosure F.This stochastic analysis only accounts for uncertainty associated with exposure because the

lexicological doses were applied as discrete input values.

As part of the use of stochastic analysis, variables that are naturally correlated are not treated asindependent. For example, ingestion rates (i.e.. food, water, and soil) typically are related to



body weights. Body weight-dependent variables were directly correlated together within thisstochastic analysis to prevent improbable scenarios from being chosen during random sampling.In this assessment, the results of the 50th, 90th, and 95lh percentile EHIs (ecological hazardindices) were compared to the deterministic EHIs.

The exposure and ecotoxicity equations used in the assessment are presented in the followingsections. Supporting documentation for all assumptions made can be found in the Enclosure F(stochastic ecological exposure assessment) or G (ecotoxicity assessment).

1.4.1.1 Exposure Assessment

Twenty exposure factors (see Enclosure F) were identified for the five exposure pathwaysindicated in Section 1.2.2. Applicable equations for the calculation of absorbed contaminant-of-potential-concern doses are:

Plant Ingestion Doses —

DpiB| = IngR fxC t /w^axUFpx(l-WC)xF f (x(l-F i)xEFxBF fxUCFmxBW-1xUCF t-1

(4-1)

Insect/Crustacea Ingestion Doses —

Dun. = IngR f xC,^ M xUF i x( l -WC)xF f .xF 1 xEFxBF f xUCF T n xBW-'xUCF t ' (4-2)

Terrestrial Animal Ingestion Doses —

DBin, = IngR fxC^ -xUF t tx(l-WC)xF f ix(l-F j )xEFxBF fxUCFmxBW-'xUCF l '(4-3)

Incidental Soil Ingestion Doses —

D..̂ = IngR^MxC,,.^MxF t txEFxBF.xUCFmxBW lxUCF t ' (4-4)

Surface Water Ingestion Doses —

D.W.™ = IngRwxC.wxF%wxEFxBFwxBW-1xUCF [1 (4-5)



The dependent dose variables (output parameters) in Equations 4-1 - 4-5 are represented as D, v,where: x indicates the environmental medium (p represents plants, i insects/crustacea, taterrestrial animals, s soil, and sw surface water); and, y indicates the exposure route (ingrepresents ingestion).

The 20 independent variables (input parameters) in the exposure equations, in the order that theyfirst appear, are:

• IngRf — food ingestion rate (mg/d);

' C./M*. — weighted concentration of chemical x in soil, surface water sediments,and leachate soil (mg/kg) for 23 COPCs;

• UFp — chemical-specific plant/soil-sediment-leachate soil uptake factor (unitless)for 23 COPCs;

• WC — water content of biological tissue (unitless);

• Ff, — fraction of food derived from site (unitless};

• F; — fraction of insect tissue in diet for the blackbird or fraction of Crustaceatissue in diet (unitless);

• EF — exposure frequency (d/yr);

• BFf — chemical-specific bioavailability factor for food (unitless) for 23 soil,surface water sediment, and leachate soil COPCs;

• UCFm — mass unit conversion factor (kg/mg);

• BW — body weight (kg);

• UCF,"1 — time unit conversion factor (d/yr);

• UF; — chemical-specific insect/soil-sediment-leachate soil uptake factor (unitless)for 23 COPCs;

• UFa — chemical-specific terrestrial animal/soil-sediment-!eachate soil uptakefactor (unitless) for 23 soil, surface water sediment, and leachate soil COPCs;

• IngR, — incidental soil ingestion rate (mg/d);

• FM — fraction of incidental soil derived from site (unitless);

• BF, — chemical-specific bioavailability factor (unitless) for 23 soil, surface watersediment, and leachate soil COPCs;



— water ingestion rate (L/d):

• Cn,, — concentration of chemical x in Yeoman Creek surface water (mg/L) for3 COPCs;

• F*, — fraction of water derived from Yeoman Creek (unitless);

• BFW — chemical-specific bioavailability factor for water (unitlass) for 10 surfacewater COPCs;

Each of the ecological exposure parameters and the distribution for those parameters are definedand accompanied by supporting rationale in Enclosure F.

1.4.1.2 Ecotoxicitv Assessment

The following is a summary of the assessment of the ecotoxicity of the COPCs found in Sitesurface soils, surface water sediments, leachate soil and surface waters to which the indicator

species, red-winged blackbird and mink, may be exposed. Surrogate RfDs were derived for theecological COPCs — found in surface water, surface water sediments, and soil — relevant to theterrestrial ecological scenario (see Enclosure G).

As noted in Enclosure G, the ecological RfDs were derived on the basis of oral dose studies.The toxicity variables are modified according to the following equation to yield absorbed-dose-basis effective RfDs:

ERfD = RfDxBFm (4-6)

where:

• RfD is the RfD for the contaminant of potential concern of interest, as notedabove; and,

• BFm is the bioavailability factor for the environmental medium of interest.

As the BF values for food, soil, and water are assumed to be L.OO, ERfD is thus equivalent toRfD for this modeling effort. It should be noted that this may he a conservative assumption for



some of the chemicals in soil (i.e., surface soil, surface water sediment, and leachate soil) thatmay be bound to the soil matrix.

1.4.2 Stochastic Ecological Risk Characterization

The stochastic risk characterization in this section consists of the following three subphases:

• Risk estimation;

• Risk description; and,

• Uncertainty analysis.

The risk estimation is undertaken by combining the toxicity tactors and exposure assessment

equations to calculate estimates of risks. These risks are reported as environmental hazardquotients and indices (EHQs and EHIs). Risk description and uncertainty analysis are presentedin the same manner used in the human health evaluation (see Section 1 .3.2). The risk estimation.risk description, and uncertainty analysis subphases are documented below in Sections 1.4.2.1,1.4.2.2, and 1.4.2.3, respectively.

1.4.2.1 Stochastic Risk Estimation

In the deterministic baseline ecological risk assessment, estimates of EHIs are calculated by

dividing the estimated dose for a particular pathway by the Ecological reference dose (ERfD).Operationally in the stochastic analysis, a distribution for each parameter value is randomlysampled and a distribution of risk estimates is created. The applicable equations for ecological

risk estimation are:

Plant Ingestion Risks —EHQP^ = Dp.bg/ERfD (4-7)

Insect/Crustacea Ingestion Risks —EHQ,^, = D^/ERtt) (4-8)

Terrestrial Animal Ingestion Risks —= D^/ERfD (4-9)



Incidental Soil Ingestion Risks —EHQ..^ = 0,^/ERtD (4-10)

Surface Water Ingestion Risks —EHQ.Wiint = 0.^/ERfD (4-11)

The effective RfDs are as defined in Equation 4-6, and the absorbed doses 'are as defined inEquations 4-1 - 4-5; the subscripts identifying each of the above dependent risk variables havethe same meaning as those used to identify doses.

A conservative approximation of the EHI for each ingestion pathway at the Site is estimated,assuming unrealistically that all COPCs affect the same target organ system of the red-wingedblackbird adult and mink. Evaluations of pathway and contaminant contributions to these riskestimates are discussed below.

Estimates of distributions for each exposure variable are documented in Enclosure F and were

used as inputs to the stochastic solution. Ecotoxicity values in Enclosure G remained discretepoint estimates. The exposure pathways of likely concern (i.e., with EHIs > 1), as identifiedin the deterministic characterization (ICF Kaiser, 1994) are carried through the stochasticcharacterization. Plant ingestion, although having EHIs below one in the deterministicevaluation, was also carried through the stochastic analysis because it could contribute to overallrisk for the red-winged blackbird.

The deterministic risk characterization tor the adult red-winged blackbird scenario identified the

ingestion of insects, incidental soil, and surface water as the exposure pathways of likely concern,assuming conservatively that exposure to all surface soil, surface water sediment, leachate soil,and surface water COPCs results in additive toxic effects. The plant ingestion pathway was alsoevaluated because it could also have an additive effect on overall risk. On the basis of stochasticmodeling of these ingestion pathways, Table H-l through H-5 indicate the results by ingestionpathway for each species.



1.4.2.2 Stochastic Risk Description

The stochastic risk estimates tor each exposure pathway are presented in Tables 13 and 14. In

the deterministic analysis, it was presumed that the average is typically more representative for

ecological impacts because the exposure concentrations are estimated tor the area over which a

population of organisms could be exposed, rather than for a particular upper bound exposure

point. The 50th percentile EHIs should receive greater attention than the upper hound EHIs

because the ecological assessment estimates should reflect the impact in the ecological population

or community rather than to the individual organism (as in human health risk assessment).

None of the EHIs at the 50th percentile are greater than one. Therefore, the average parameters

used were sufficiently conservative when combined with other input parameters from the high end1 of distributions. The assumption of additivity of the toxic effects of all the COPCs is very

conservative. It is unlikely that all of the COPCs have similar toxicological endpoints.

The upper bound deterministic EHIs are all above the 90th percentile of the distribution derived

from the stochastic analysis. This further suggests that the use of the upper bound deterministic

estimates are highly conservative.

The likelihood of adverse effects to a sensitive member of the local blackbird or mink population

may exist based on the stochastic results. However, as ecological effects of interest are for the

population rather than organism level, the stochastic results suggest that the population is not at

risk.



Table 13 indicates the results of the exposure pathway analysis for the adult red-winged

blackbird. It is apparent that insect and incidental soil ingestion. with EHIs between 0.6 and 2.32

contribute approximately the same relative amount of risk. Surface water and plant ingesiion,

with EHIs for the average and upper bound scenarios both below one even at the 95th percentile.

are not considered significant contributors to overall risk in comparison with these other ingestion

pathways.

Analysis of the data in Table 13 suggests that the COPCs that are major contributors to risk for

the red-winged blackbird are lead, Aroclor 1242. Aroclor 1248, benzo(a)pyrene,

benzo(b)fluoranthene, benzo(k)fluoranthene, and chrysene in surface soil, surface water sediment,

and leachate soil. However, these chemicals do not have an EHQ above one individually in

either the soil or insect ingestion scenarios.

The deterministic EH! estimates are greater than one for two of the four adult red-winged

blackbird exposure pathways (insect and incidental soil ingestion). However, these risk estimates

are derived assuming that the effects of exposure to all COPCs are additive. This is unlikely for

many of the COPCs. Thus, the EHIs are likely to be lower if the target organs are taken into

account. With this in mind, lead appears to be the primary chemical of concern tor adult red-

winged blackbird as it is the greatest contributor to risk for both the insect and soil ingestion

pathways.

Table 14 indicates the three exposure pathways evaluated under the mink scenario. It is apparent

that ingestion of terrestrial animals, with EHIs of 0.33 to 1.68. is the most significant contributor

to overall risk. However, EHIs for the soil ingestion pathway at the 95th percentile is greater



than one, suggesting the possibility of adverse impacts for this pathway. The major contributor

to risk for mink is lead; however, at the 95th percentile: no individual chemical has an EHI of

greater than one. Two sources of uncertainties should be considered at this point. First, it is

important to note again that these risk estimates are derived assuming that the effects of exposure

to all COPCs are additive. This is unlikely for many of the COPCs. Second, the Site, as noted

in Section 1.4.2.3, does not provide suitable habitat for mink. If mink were to habitat the Site,

the Site could support very few. Thus, local population impacts are unlikely for mink at the Site.

As discussed in Section 1.4.2.3 below, there is substantial uncertainty associated with these

estimates.

1.4.2.3 Uncertainty Analysis

As noted above, quantitative uncertainty analyses cannot be conducted for deterministic

assessments. However, a stochastic ecological assessment is presented in previous sections that

produces output that can be used for comparison with the deterministic EHIs. Most of the

uncertainty in this stochastic analysis was also an uncertainty in the deterministic assessment.

One uncertainty is the assumption of additivity of chemical effects when the target organ, type

of toxicity, and mechanism of action among chemicals may be very different. Another

uncertainty held in common with the deterministic assessment is the assumption that mink could

be present at the Site. It is unlikely that mink will inhabit the Site because of its location as an

isolated block of open space surrounded by commercial and residential development and because

of the intermittent nature of Yeoman Creek would limit populations of aquatic prey. Quality

terrestrial aquatic environments are not contiguous with the Site, so transient visitors are also not

expected. Furthermore, fish, one of the primary dietary items of mink, are not present in



Yeoman Creek. Thus, although EHIs tor mink were higher than tor adult red-winged blackbird.

they are unlikely to occur at the Site and the results should be interpreted with this in mind.

The results presented in Section 1.4.2.2 indicate that the average deterministic estimates of EHIs

tor both red-winged blackbird and mink all fall between the 50th and 90th per cent iles of the

estimated EHI distributions, with the exception of surface water. The average deterministic

estimate for surface water is greater than the 95th percentile. The average deterministic EHIs,

being above the 50th percentile, are thus also above the mode (most frequently occurring EHI

value in the distribution). The upper bound deterministic estimates of EHIs alt are at or exceed

the 90th percentile. In many cases the upper bound deterministic EHIs are above the 99th

percentile. The results suggest that the deterministic estimates for adult red-winged blackbird and

mink are overly conservative.

1.5 Summary and Conclusions

The purpose of this chapter is to summarize the results of the baseline risk assessment for the

Yeoman Creek/Edwards Field Landfills Site. The human health evaluation summary is provided

below in Section 1.5.1, and the ecological evaluation summary is provided in Sections 1.5.2.

Both evaluations are conducted in three phases: problem formulation; analysis; and, risk

characterization. Problem formulation consists of identifying contaminants, receptor populations,

and exposure pathways of potential concern. Analysis consists of toxicity and exposure

assessments. Risk characterization consists of risk estimation, risk description, and uncertainty

analysis. The results of each phase are summarized in sections within each subchapter.



Two types of modeling are used to estimate risks: deterministic and stochastic. The exposure

algorithms and toxicity values used are identical for both types of modeling. The primary

difference between the two approaches is in how the variables in the equations are treated. In

the deterministic model, each input variable is treated as a point estimate: as a result, the output

of the deterministic model is also a point estimate. In the stochastic model, the input variables

(except for unit conversion factors and a few other factors) are treated as random factors

represented by probability distributions; as a result, the output of the stochastic model is a

distribution or range of values.

Stochastic modeling enhances realism by allowing one to incorporate estimates of both random

variability within the environment and uncertainties due to lack of knowledge. Another advantage

of stochastic modeling is the procedure allows for quantification of overall uncertainty (i.e.,

variability and lack of knowledge combined) in the output.

1.5.1 Human Health Evaluation Summary

1.5.1.1 Human Health Problem Formulation

Conceptual modeling and discussions with USEPA-5 have resulted in the identification of three

human exposure scenarios requiring quantitative evaluation:

• A current Adjacent Residential Scenario;

• A Site Occupational Scenario; and,

• A Future Adjacent Residential Scenario with exposure to hypothetical users ofthe shallow and outwash sand and gravel groundwater flow systems.



The Adjacent Residential Scenario consists of seven exposure pathways, the Site occupationalscenario consists of two exposure pathways, and the Future Adjacent Residential Scenarios consistof ten exposure pathways. The relevant pathways for each scenario (subscenario for future

groundwater use) are listed below along with the associated COPCs identified by a preliminaryrisk-based screening procedure:

1-5.1.2 Human Health Analysis

In the toxicity assessment, cancer potency for chemicals classified as carcinogens are evaluatedby means of SFs that assume cancer risk is directly proportional to dose. Noncarcinogenictoxicities are evaluated by means of RfDs.

Equations for estimating doses associated with each of the exposure pathways of potential concern

are developed in the exposure assessment. Two equations are given for each pathway: one forcalculating a dose relevant to cancer risk; the other for calculating a dose relevant to noncancerrisk. Bioavailability is taken into account when the data are available (specifically in the dermalcontact pathway).

1.5.1.3 Human Health Risk Characterization

The stochastic risk characterization phase of the human health evaluation was conducted in three

subphases: risk estimation, risk description, and uncertainty analysis. The result of each

subphase is summarized below in Sections 1.5.1.3.1, 1.5.1.3.2. and 1.5.1.3.3. respectively.

1.5.1.3.1 Stochastic Risk Estimation

Cancer risk is estimated by means of an incremental lifetime cancer incidence rate. (For

comparison purposes, the lifetime cancer incidence rate in North America is about 0.25



[2.5x lO'1).) While a 1 x 10'6 cancer risk is generally considered to be USEPA's benchmark, a

risk range of 1 x 10"* to 1 x 10"6 is used by USEPA at Superrund sites in the evaluation of remedial

alternatives, and is considered to be an acceptable risk range (USEPA, 1990). USEPA's Office

of Solid Waste and Emergency Response (OSWER) has issued further guidance clarifying the role

of risk assessment in the Superrund process (USEPA. 1991b). This directive states that where

the cumulative current or future carcinogenic risk to an individual is less than 10~4, and where

the noncarcinogenic hazard quotient is less than one, action generally is not warranted unless

there are adverse environmental impacts.

The USEPA generally regards an incremental lifetime cancer incidence risk (ILCR), attributable

to human-caused releases of chemicals classified as carcinogenic substances into the environment,

in excess of ICT* as unacceptable; however, the agency retains the right to lower the acceptable

incremental risk on a site-specific basis down to 106. In order to calculate carcinogenic risks,

the chemical-and pathway-specific doses, calculated as described in Enclosure C, are multiplied

by oral or inhalation SFs. The resulting values represent the upper-bound probability that an

individual could develop cancer over his or her lifetime due to exposure to potential carcinogens

under the conditions specified in the exposure scenario. For example, a carcinogenic risk level

of 1 x 10"6 represents a one in one million chance that an individual could contract cancer over

a lifetime.

Noncancer risk is estimated by means of an HI. USEPA interprets an HI greater than one to be

an indicator of potential toxic effects; however, an HI greater than one should not automatically

be interpreted as posing a hazard to the exposed population. In order to calculate

noncarcinogenic hazard quotients, the doses, calculated as described in Enclosure C, are divided

ICE Kaiser InternationalFinal - March, 1994


by the oral or inhalation RfDs. The sum of this ratio tor all chemicals within a pathway, which

have the same target organ or type of toxicity, is termed the HI. The HI is useful as a reference

point for gauging potential effects of environmental exposures to complex mixtures. In general,

hazard indices which are less than one are not likely to be associated with any health risks, and

are therefore less likely to be of regulatory concern than hazard indices greater than one;

however, a hazard index (HI) of greater than one does not automatically indicate that an adverse

impact will occur.

1.5.1.3.2 Risk Description

In this section, the human health risks potentially associated with exposures to environmental

media (soil, sediment, surface water, groundwater, air) are summarized. Individual chemical-

specific carcinogenic risks are expressed as probabilities of contracting cancer, while

noncarcinogenic risks are expressed as thresholds known as hazard quotients.

All carcinogenic and noncarcinogenic risks were calculated using the traditional Reasonable

Maximum Exposure (RME) method. These RME estimates are considered to be conservative

bounding estimates of risk, as described in Section 1.5.5. Therefore, if the RME cancer risk

estimate for a pathway was less than 1 x 10**, and the noncarcinogenic HI was less than one. the

pathway was determined to not be of concern with respect to human health. For this assessment,

none of the pathways by which noncarcinogenic hazards were assessed resulted in a hazard

quotient greater than one.



1.5.1.3.2.1 Risks Associated u lii Residential Scenario

The Adjacent Residential Receptor was defined assuming that access restrictions and institutional

controls were not effective. It was assumed that this Receptor had free access to Site

contaminants in I each ate seep soil, surface soil, and sediments. This Receptor was also assumed

to be exposed to soil gas that migrated from the Site to an adjacent resident. The incremental

lifetime cancer risk for each of the pathways in the residential scenario are below i x l O " 6 .

Estimates of the incremental lifetime cancer risk for exposure by way of all pathways for the

Adjacent Residential Receptor is 9.1xlO"9 in the 50th percentile and SxlO"7 for the 95th

percentile.

1.5.1.3.2.2 Risks Associated with the Hypothetical Future Residential Receptor

The Future Residential Scenario Receptor is defined the same as in the deterministic analysis in

that it assumes access restrictions and institutional controls are not effective and ground water

usage occurs. Future groundwater use is assurm"! for this Receptor even though all area residents

are currently served by munic :i water sources derived from Lake Michigan. If the future

residents continue to receive their water supply from a municipal source, then the major

contributors to risk by these pathways are the same as those discussed in the previous section for

the current Adjacent Residential Receptor. The stochastic estimates of incremental lifetime cancer

risks when the shallow groundwater was used as the source was 2.6x 10"7 and l .2x 10"° at the

50th and 95th percentile for all nongroundwater and groundwater pathways. The contribution

of the groundwater pathways alone represents approximately 72% of the total estimated risks for

the RME for - i*5th percentile.



The stochastic, estimated incremental lifetime cancer risk that may he associated with both

ingestion of shallow groundwater and inhalation of volatiles released from shallow groundwater

during normal household usage was approximately 2.9xlO"6 . This risk was based on the

estimated risks associated with exposure primarily to vinyl chloride in the shallow groundwater.

Vinyl chloride was retained for this pathway following preliminary screening. Estimated cancer

risks that may be associated with ingestion and inhalation pathways were 2x 10"6 and 3x I0"?,

respectively, at the 95th percentile. At the 50th percentile, these incremental risks were 4x 10"7

and 7x 10"1 for ingestion and inhalation. The deterministic risks for these pathways were an

order of magnitude higher and were at greater than the 99th percentile. The inclusion of vinyl

chloride is considered to be conservative. Vinyl chloride was detected in only 2 samples tested

at estimated concentrations of 0.002 mg/L and 0.003 mg/L. All other samples were below the

detection limit of 0.001 mg/L. The MCL for vinyl chloride is 0.002 mg/L and is currently under

review as is the cancer SF.

With the lower outwash as the source of groundwater, the stochastic estimates of incremental

lifetime cancer risk were less than 1 x 10'6 (95th percentile) for any chemical in any groundwater

pathway, and the sum of all groundwater pathways was also less than 1 x 10"6 at the 95th

percentile. These results clearly indicate that the risk to an Adjacent Residential Receptor with

future access to groundwater, either shallow or lower outwash. would be insignificant.

As discussed previously, lead was maintained in the assessment qualitatively for human health

risk assessment because no toxicology values have been established. No MCL exists for lead;

however, there is an action level of 0.015 mg/L (USEPA I99lb). The maximum detected

concentration for lead in the shallow groundwater was 0.085 mg/L, which is above the action



level of 0.015 mg/L; however, the 95% upper bound on the arithmetic mean was well below this

value. The action level for lead is applicable to source waters, and hence to groundwater;

however, the intent of the action level is to control levels between the source and the residential

user (USEPA 1991b). The final action level for lead is exceeded only if the level of lead in more

than 10% of targeted tap samples is greater than 0.015 mg/L (USEPA 1991b).

The main consideration, however, in the evaluation of these risks is the likelihood that either the

shallow or lower outwash aquifers will be used for residential drinking water. It is highly

unlikely that it will be feasible to use these wells as a drinking water source because of the nature

of these aquifers (Colder 1994). In addition, the City of W auk eg an and other municipalities in

the area are already served by water derived from Lake Michigan.

1.5.1.3.2.3 Risks Associated with Occupational Scenario Exposure Pathways

Only soil ingestion and direct contact with soil were considered quantitatively for the occupational

scenarios in this stochastic analysis. The stochastic incremental lifetime cancer risk estimate was

9.7xlO"7 for both pathways for the 95th percentile. The contribution from the soil ingestion

pathway was 1.8x 10'7. while the soil dermal contact pathway estimates totaled 7.9x IO"7. Even

with the stochastic analysis, there are several factors associated with these chemicals that strongly

suggest that these estimated risks are overestimates for these chemicals. It is conservatively

assumed that the worker will be at the Site for 25 years, and therefore, the distribution for these

parameter values exceeded 25 years at the high end of the distribution. Since deed restrictions

preclude development or public access at the Site, the only workers likely would be those

involved in Site-related activities, such as potential remediation, for which the duration of



exposure would be for a much shorter length of time than 25 years. In addition, the assumption

that surface area could come in contact with soil is larger than would be expected since a worker

involved in remedial activities would be expected to wear protective clothing and follow a rigid

health and safety plan. Therefore, these estimates of risk to Site workers are not considered

significant.



1.5.1.3.3 Uncertainty Analysis

Estimation of risks to human health that may result from exposure to chemicals in the

environment is a complex process that often requires the combined efforts of multiple disciplines.

In each' step of the risk assessment process from the data collection and 'analysis, toxicity

assessment, exposure assessment, and risk characterization, conservative assumptions are made

that are intended to be protective of human health and to ensure that estimates of risk are not

underestimated. However, each assumption, whether regarding the toxicity value to use tor a

particular chemical or the value of a parameter in an exposure equation, has a degree of

variability and uncertainty inherent to it. In exposure paradigms where parameter values are

multiplicative, the degree of conservatism increases. The final values, if placed on an appropriate

distribution, would be likely higher than the 99% rather than the 95% as intended.

Unfortunately, deterministic estimates, i.e., a point value, are difficult to quantify so that the

major contributor to uncertainty is not easily ascertained or quantified. The various types of

uncertainty are discussed in previous sections.

1.5.2 Ecological Evaluation Summary

1.5.2.1 Ecological Problem Formulation

Conceptual modeling and discussions with USEPA-5 resulted in the identification of three

terrestrial ecological exposure scenarios requiring quantitative evaluation: a local red-winged

blackbird scenario, a red-winged blackbird nestling scenario, and a mink scenario. These

scenarios consist of from one to four of the following five exposure pathways: plant ingestion,



insect/Crustacea ingestion, terrestrial animal ingestion, incidental soil ingestion, and surface water

ingestion. However, the results of the deterministic assessment indicated no potential risk to the

red-winged blackbird nestling (upper bound EHI for insect ingestion was 0.21); therefore, it was

not included in this analysis.

The COPCS for the surface water ingestion pathway are acetone, cyanide, and zinc. The COPCs

for the insect, Crustacea, plant, terrestrial animal, and incidental soil ingestion pathways are lead,

acenaphthene, anthracene, Aroclor-1242, Aroclor-1248, Aroclor-1254, benzo(a)anthracene,

benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(g,h,i)perylene, chrysene,

dibenzo(a,h)anthracene, dieldrin, fluorene, and indeno(l,2,3-c,d)pyrene.

1.5.2.2 Ecological Analysis

In the ecotoxicity assessment, the toxicities of the COPCs are evaluated by means of ecological

RfDs derived from a variety of ecotoxicological values. Equations for estimating doses associated

with each of the five exposure pathways of potential concern are developed in the exposure

assessment (Enclosure C). For the purposes of the ecological risk assessment, alt COPCs,

whether ingested from plants, insects, Crustacea, soil, or water are conservatively assumed to be

totally bioavailable.

1.5.2.3 Ecological Risk Characterization

The stochastic risk characterization phase of the ecological evaluation is conducted in three

subphases: risk estimation, risk description, and uncertainty analysis. The results of each of



these subphases is summarized below in Sections 1.5.2.3.1, 1.5.2.3.2. and 1.5.2.3.3,

respectively.

1.5.2.3.1 Ecological Risk Estimation

Ecological risk is estimated by means of an ecological hazard index (EHI). USEPA generally

interprets an EHI greater than one to be an indicator of potential toxic effects. The deterministic

and stochastic EHIs for some (incidental soil, insect, Crustacea, and terrestrial animal) of the adult

red-winged blackbird and mink ingestion scenarios are greater than one under the conservative

assumption that all COPCs have identical toxicological effects. Surface water ingestion does not

appear to have an adverse impact on adult red-winged blackbird.

1.5.2.3.2 Ecological Risk Description

Of the five exposure pathways considered in this ecological risk characterization, terrestrial

animal ingestion by mink had the greatest EHI at the 95th percentile (1.68). Lead was the

contaminant of most concern in this specific pathway at the Site. The insect, Crustacea, terrestrial

animal, and incidental soil ingestion pathways were analyzed to determine the specific

contaminants of concern. No individual COPCs had an EHQ greater than one, even at the 95th

percentile.

1.5.3 Summary and Conclusions



Two complete analyses have been conducted that form a baseline risk assessment for the Site -

a deterministic and a stochastic assessment. Both assessments used the same exposure algorithms

and toxicity values; however, parameter values were treated either as point estimates (95% upper

bound for human and average for ecological) or as probability distributions (95th percentile).

Based on the use of conservative exposure assumptions, i.e., a leachate seep/soil pathway and

a hypothetical highly unlikely groundwater use in the human health assessment, it is highly

unlikely that contact with contaminants at the Site by any of the pathways evaluated would pose

an unacceptable risk to human health.

Based on the conservative assumptions used in the ecological stochastic assessment, some of the

95th percentiles are greater than one for some pathways for both the mink and the red-winged

blackbird. However, it is questionable as to whether the Site could actually support mink. The

Site is an isolated block of open space surrounded by commercial and residential development.

In addition, the intermittent nature if Yeoman Creek would limit populations of aquatic prey.

The Site is surrounded by urban areas which would discourage the presence of terrestrial anaimals

requireing a large home range, which include the mink, and Yeoman Creek cannot support fish,

which is a major component of the mink's diet. For the red-winged blackbird, no individual

chemical has an HI greater than one; however, the total for the soil ingestion pathway exceeded

one. This indicates that should exposure occur to Site concentrations occur as specified, there

is the potential for an adverse impact on the red-winged blackbird. The major contributors to

the soil ingestion pathway (soil, seep, and sediment) were lead, found only in sediments, Aroclor

1242, found only in seep soil, and certain PAHs, generally found in background samples.

However, given the conservative assumptions, it is highly unlikely, that contact by ecological



receptors with any of the contaminants at the Site by way of any of the pathways evaluated could

pose an unacceptable risk to ecological receptors.



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Table 1Exposure Pathway Contribution to Incremental Lifetime Cancer Risk -

Adjacent Residential Scenario

Pathway

ILCR.^

ILCR*^

ILCR.,.^

ILCR.A

ILCR..*

ILCR^

ILCR^

50 %ile

3.8E-13(<0.1%)

i.3E-12(<0.1%)

7.3E-09 (80.0%)

4.3E-12(<0.1%)

2.2E-11 (0.2%)

1.8E-09 (19.5%)1.6E-11 (0.2%)

90 %Ue

1.8E-09(0.7%)

8.9E-10(0.3%)

9. IE-08 (34.5%)

7.4E-08 (27.8%)

4.8E-08(18.1%)

4.9E-08(18.4%)

4.6E-10(0.2%)

95 %ile

5. IE-09 (0.9%)

3.0E-09(0.5%)

1.7E-07(29.6%)

1.7E-07(29.6%)

1.4E-07(23.5%)

9.0E-08(15.6%)

1.3E-09(0.2%)

Total 9. IE-09 2.6E-07 5.8E-07

(a) Number in parentheses is percent contribution to total risk.


83

Table 2aExposure Pathway Contribution to Incremental Lifetime Cancer Risk

Future Adjacent Residential Scenario (a)

Pathway

ILCR^

ILCR^

ILCR.^

ILCR^

ILCR.,^

ILCRIwllc

ILCRiwins

ILCR^tni,

ILCRp^jc

ILCRp^g

Resident using municipal ground water

50 %ile3.8E-13<<0.1%)

l .3E-12(<0.1%)

7.3E-09 (80.0%)

4 .3E-I2(<O.I%)

2.2E-U (0.2%)

I.8E-09(19.5%)

I .6E-1I (0.2%)

90%ileI.8E-09(0.7%)

8.9E-10(03%)

9.IE-08(34.5%)

7.4E-08 (27.8%)

4.8E-08 ( 1 8 . 1 % )

4.9E-08(I8.4%)

4 6 E - I O ( 0 2 % )

95 %ile

5. IE-09 (0.9%)

3'.OE-09 (0.5%)

I.7E-07(29.6%)

I.7EX)7(29.6%)

1 4E-07 (23.5%)

9.0E-08 (15.6%)

1 3E-09(0.2%)

Resident with unfiltered/filtered shallow groundwater

50%ile3.8E-13(<0.1*)

1 . 3 E - I 2 ( < O . I * )

7.3E-09(i.3%)

4.3E-12(<0.1%)

2.2E-11 (<0.\%)

I.^E-09 (0.3%)

1.6E-II (<0.1%)

7.7E-08(I3.4%)

7.7E-08(I3.4%)

4.1E-07(7I .6%)

90%ileL8E-09 (<0.1%)

8.9E-10(<O.I%)

9. IE-08 (3.4%)

7.4E-08 (2.8%)

4.8E-08 (1.8%)

4.9E-08(I.8%)

4.6E-10(<O.I%)

2.7E-07(I02%)

4.4E-07 (16.6%)

1.7E-06 (63.3%)

95 %ile

5. IE-09 (0.1%)

3.0E-09(<O.I%)

I.7E-07 (4 .1%)

I .7E-07(4 .1%)

1.4E-07(3.3%)

9.0E-08 (2.2%)

1.3E-09 ( < 0 . l % )

3.7E-07 (9.0%)

6.6E-07 ( 1 5 . 9 % )

2.5E-06 ( 6 1 . 1 % )

Total 9. IE-09 2.6E-07 5.8E-07 5.7E-07 2.7E06 4 IE 06


84

Table 2bExposure Pathway Contribution to Incremental Lifetime Cancer Risk -

Future Adjacent Residential Scenario (a)

Pathway

ILCR^

ILCR^

ILCR^

ILCRi>(lc

ILCR,^

ILCR,wA.

ILCR^jng

ILCRgw.inh

ILCRp^

ILCR^

Resident using municipal groundwater

SO %ile3.8E I3{<0 1%)

1.3E-12(<0.1%)

7.3E-09 (80.0%)

4.3E-I2(<OI%)

2.2E-II (0.2%)

I.8E-09(19.5%)

1.6E-11 (0.2%)

90%ile

I.8E-09<0.7%)

8.9E-10(0.3%)

9. IE-08 (34.5%)

7.4E-08 (27.8%)

48E-08 (18.1%)

4.9E-08 (18.4%)

4.6E-10(0.2%)

95 %ile5. IE-09 (0.9%)

3.0E-09 (0.5%)

I.7E-07(29.6%)

I.7E-07(29.6%)

I.4E-07(23.5%)

9 OE -08 (15 6%)

I.3E-09(0.2%)

Resident with un filtered /filtered outwash groundwater

SO %ile3.8E-I3(<O.I%)

1.3E-12(<O.I%)

7.3E-09 (2.8%)

4.3E-12(<0.1%)

2.2E-I1 (<0. l%)

1.8E-09(0.7%)

I.6E-II (<0.1%)

3.9E08(149%)

9.4E-08 (36.0%)

1.2E-07(45.6%)

90 %ile1 8E-09(0.1%)

8.9E-10(<0.1%)

9 IE-OS (6 9%)

7.4E-08 (5.6%)

4.8E-08 (3.6%)

4.9E-08 (3.7%)

4.6E-IO(<0.1%)

1.2E-07(95%)

4.5E-07 (34.1%)

4.8E-07 (36.4%)

95 %ile5. IE-09 (0.2%)

3.0E-09(O.I%)

I.7E-07(8.0%)

I.7E-07(8.0%)

I.4E-07(6.3%)

9.0E-08 (4.2%)

I.3E-09{<0 1%)

1.6E-07(77%)

6.5E-07 (30 6%)

7.4E-07 (34.8%) _ .

Total 9. IE-09 2.6E^>7 5.8E-07 2.6E-07 1.3E-06 2 IE 06



Table 3Exposure Pathway Contribution to Incremental Lifetime Cancer Risk -

Occupational Scenario (a)

Pathway

ILCRH],4;

ILCR^

50 %iie

3.6E-12 (9.1%)

3.6E-11 (90.9%)

90 %ile

4.0E-07(72.6%)

1.5E-07 (27.4%)

95 %ile

8.0E-07(69.9%)

3.4E-07(30.1%)

Total 3.9E-11 5.4E-07 1. IE-06




Table 4Exposure Pathway Contribution -

Adjacent Residential Noncarcinogenic Scenario (a)

Pathway

Hld.dc

Hld.in,

Hl.g.inh

HUHUHI,w.4e

HT»W,1B(

50 %ile

1.9E-09(<0.1%)3.4E-07 (0.4%)

1.3E-06(1.7%)

3.0E-08(<0.1%)

3.6E-07 (0.5%)

7.4E-05 (97.0%)

2.7E-07 (0.4%)

90 %ile

3.5E-08(<0.1%)

7.4E-06 (0.9%)

1.6E-04(19.8%)

1.4E-06(0.2%)

3.7E-05(4.6%)

5.9E-04(73.5%)

7.9E-06(1.0%)

95 %iie

7.9E-08 (<0 .1%)

1.7E-05(l . l%)

4. IE-04 (26.8%)

3.7E-06(0.2%)

1.5E-04(9.9%)

9.2E-04 (60.8%)

1.8E-05(1.2%)

Total 7.6E-05 8.0E-04 1.5E-03



Table 5aExposure Pathway Contribution -

Future Adjacent Residential Noncarcinogenic Scenario (a)

Pathway

HU^c

HIrf.bg

HI,8.«h

HUHl..ing

Hl^.de

HI***•*. ing

HIgw.dc

H'gw.^


50 %ile

I.9E-09(<O.I%)

3.4E-07 (0.4%)

I.3E-06<1.7%)

30E-08 (<0.1%)

3.6E-07 (0.5%)

7.4E-05 (97.0%)

2.7E-07 (0.4%)

90 %ile3.5E-08(<O.I%)

7.4E-06 (0.9%)

l.6E-04(19.8%)

1.4E-06(0.2%)

3 7E-05 (4.6%)

5.9E-04 (73.5%)

7.9E-06(I.O%)

95 %He

7.9E-08(<0.1%)

1.7E-05(I.I%)

4. IE-04 (26.8%)

3.7E-06 (0.2%)

I.5E-04(9.9%)

9.2E-04 (60.8%)

I.8E-05(1.2%)

Resident with un filtered /filtered shallow groundwater

50 %ile

1.9E-09(<0.1%)

3.4E-07(<0 1%)

1.3E-06(<O.I%)

3.QE-Q& (<0.1%)

3.6E-07(<0.t%)

7.4E-05 (1.1%)

2.7E-07(<0.]%)

5.7E-03 (85.5%)

8.9E-04(13.3%)

90 %ile3.5E-08(<O.I%)

7.4E-06(<0.1%)

1.6E-04(0.6%)

I.4E-06(<0.1%)

3.7E-05(0.1%)

5.9E-04 (2.3%)

7.9E-06 (<0.1%)

1.9E-02 (75.4%)

5.4E-03 (21 4%)

95 %ile

7.9E-08(<0.1%)

I.7E-05(<0.1%)

4.1E-04(1.2%)

3.7E-06(<0 1%)

1.5E-04(0.4%)

9.2E-04 (2.7%)

I.8E-05 (<0 .1%)

2.4E-02 (69.9%)

8.6E-03 (25.6%)

Total 76E-05 80E-04 1.5E03 6.6E03 2.5E-02 3.4E02


Table 5bExposure Pathway Contribution -

Future Adjacent Residential Noncarcinogenic Scenario (a)

Pathway

HI«ijc

Hiding

Hl.j.iah

HI..JC

HI..̂

Hl^.dc

HI** tw.ing

HIgw.ac

H'gwng


50 %ile1 9E09(<0 1%)

3 4E-07 (0.4%)

1.3E-06(I.7%)

30E-08 (<0 1%)

3.6E-07 (0.5%)

7.4E-05 (97 0%)

2.7E-07 (0.4%)

90 %ile3.5E-08(<0.1%)

7.4E-06(0.9%)

1.6E-04(I98%)

I.4E-06(0.2%)

3.7E-05 (46%)

5.9E-O4 (73 5%)

7.9E-06(I.O%)

95 %ile

7.9E-08(<O.I%)

1.7E-05(1.1%)

4 IE-04 (26 8%)

3.7E-06 (0.2%)

1.5E-04(9.9%)

9.2E-04 (60 8%)

1 8E05 (1.2%)

Resident with un filtered /filtered out wash groundwater

50 %ile1.9E-09(<0.1%)

34E-07 (<0.l%)

1.3E-06(<0.1%)

3.0E-08(<0.1%)

3.6E-07 (<0.l%)

7.4E 05 (0.7%)

27E-07 (<0 1%)

3.8E-03 (36.7%)

6.5E-03 (62.5%)

90%ile3.5E-08(<0.1%)

7.4E-06(<O.I%)

1.6E-04 (0.3%)

I.4E-06(<O.I%)

3.7E-05(<0.1%)

5.9E-04(1.1%)

7.9E-06(<O.I%)

I.4E-02 (26.6%)

3.8E-02 (71.9%)

95 %ile7.9E-08(<O.I%)

I.7E-05(<O.I%)

4.1E-04(06%)

37E-06(<O.I%)

1.5E-04(0.2%)

9.2E-04(1.3%)

1.8E-05(<0.1%)

1.8E02 (253%)

5. IE-02 t725^|

Total 76E-05 8.0E-04 1 5E-03 1 OE-02 5.2E-02 7. IE 02



Table 6Exposure Pathway Contribution -

Occupational Noncarcinogenic Scenario (a)

Pathway

HIo.!.̂

*"*!.««

50 %ile

4.9E-08 (54.0%)

4. IE-08 (46.0%)

90 %ile

2.0E-06(38.3%)

3.2E-06(61.7%)

95 %ile

5.0E-06(34.4%)

9.5E-06 (65.6%)

Total 9.0E-08 5. IE-06 1.4E-05




Table 7Contaminant Contribution to Incremental Lifetime Cancer Risk -

Adjacent Residential Scenario (a)

Chemical

ArocIor-1242

ArocIor-1248

Aroclor-1254

Arsenic

Benzo(a)pyrene

Benzo (b)fl uoranth ene

Benzene

Beryllium

Bromodichloromethane

Dibenzo(a,h)anthracene

Dieldrin

Methylene chloride

Pentachlorophenol

Tetrachloroethylene

Trichloroethylene

Vinyl chloride

50 %ile

O.OE+00(0.0%)

1.9E-11 (0.2%)

O.OE+00(0.0%)

4.3E-11 (0.5%)

1.3E-11 (0.1%)

2.8E-12(<0.1%)

1.7E-09 (18.3%)

O.OE+00(0.0%)

1.5E-11 (0.2%)

2.5E-13(<0.1%)

O.OE+00(0.0%)

O.OE+00(0.0%)

1.7E-09 (19.0%)

O.OE+00(0.0%)

O.OE+00(0.0%)

5.6E-09 (61.7%)

90 %ile

1. IE-07 (41.1%)

1.2E-08(4.6%)

O.OE+00(0.0%)

5.0E-10(0.2%)

2.3E-09 (0.9%)

5.7E-10(0.2%)

3.0E-08(11.4%)

O.OE+00(0.0%)

1.1E-10(<0.1%)

4.9E-11 (<0.1%)

4.5E-10(0.2%)

1.2E-14(<0.1%)

4.8E-08(18.3%)

4.1E-11 (<0.1%)

2.9E-10(0.1%)

6.1E-08 (23.0%)

95 %ile

2.8E-07 (48.2%)

2.7E-08 (4.7%)

6.3E-11 (<0.1%)

1. IE-09 (0.2%)

6.2E-09 (1.1%)

1.5E-09(0.3%)

6.2E-08 (10.8%)

O.OE+00(0.0%)

1.9E-10(<0.1%)

1.4E-10(<0.1%)

1.6E-09(0.3%)

2.5E-12(<0.1%)

8.9E-08(15.5%)

l .2E-10(<0.1%)

1.2E-09(0.2%)

1. IE-07 (18.6%)

Total 9. IE-09 2.6E-07 5.8E-07



Table 8a iContaminant Contribution to Incremental Lifetime Cancer Risk - Future Adjacent Residential Scenario (a)

'

1Chemical

Aroclor-1242

Aroclor-1248

Aroclor 1254

ArsenicBenzo(a)pyrene

Benizo(b)fluoranthene

Benzene

Beryllium

Bis(2-ethylhexyl)phthalate

Bromodichloro methane

D ibenzo(a , h )anthr acene

Dieldrin

Methylene chloride

Pentachlorophenol

Tetrachloroethylene

Trichloroethylene

Vinyl chloride


50%ileO.OE+OO (0.0%)

I.9E-II (02%)

O.OE+OO (0.0%)

4.3E-I1 (0.5%)

1.3E-I1 (0.1%)

2.8E-I2 (<0.1%)

1.7E-09<18.3%)

O.OE+OO (0.0%)

1.5E-II (0.2%)

2.5E-13 (<0 . l%)

O.OE+OO (0.0%)

O.OE+OO (0.0%)

l.7E-09(]9.0%)

O.CiE+00(0.0%)i

O.OE+00 (0.0%)

5.6E-09(61.7%)

90 %ile

I. HE-07 (41.1%)

K2E-08(4.6%)

0 uL » 00 (0.0%)

5.0E-IO(0.2%)

2.3E-09 (0.9%)

5.7E-10(0.2%)

3.0E-08 (11.4%)

O.OE+OO (0.0%)

1.1E-IO(<0.1%)

4.9E-1I (<0.1%)

4.5E-IO(02%)

l .2E-14(<0 . l%)

4 81:08(18 3%)

4.1'E-M (<0.1%)

2.9E-IO(0.1%)

6. IE-08 (23.0%)

Total 9. IE-09 2.6E-07

95 %ile

2.8E-07 (48.2%)

2.7E-08 (4.7%)

6.3E-I1 (<0.l%)

1.1 £-09(0.2%)

62E-09(1.I%)

1.5E-09(0.3%)

6.2E-08 (10.8%)

O.OE+OO (0.0%)

I.9E-10(<O.I%)

I.4E 10(<0 1%)

1.6E-09(b.3%)

2 . 5 E - I 2 I ( < O . I % )

8.9E-08 (15.5%)

1.2E-IO(<0.1%)

1.2E-09(0.2%)

1. IE-07 (18.6%)

Resident with unfiltered /filtered shallow ground water50%ile

O.OE+OO (0.0%)

1.9E-II (<0.1%)

O.OE+OO (0.0%)

! 4.3E-1I (<0.1%)

1.3E-I1 (<0.l%)

2.8E-12(<0.1%)

3.8E-08 (6.7%)

O.OE + OO (0.0%)

8.0E-08(I3.9%)

I.5E-11 (<0.1%)

2.5E-13 (<0.1%)

O.OE + OO (0.0%)

8.8E-IO l(0-2%)

I.7E-0?(0.3%)

O.OE + OO (0.0%)

O.OE + OO (0.0%)

4.5E-07 (78.9%)

5.8E-07 5.7E-07

90 %ile

1.1 £07(4.1%)

1.2E-08 (0.5%)

OOE+00(0.0%)

5.0E-IO(<0 1%)

2.3E-09(<0.1%)

5.7E-10(<O.I%)

3.3E-07(12.5%)

O.OE+OO (0.0%)

4.4E-07 (16.5%)

I .1E- IO(<0 .1%)

4.9E-II (<0.1%)

4.5E-IO(<0 1%)

5.6E-04 (0.2%)

4.8E-<p8 (1.8%)

4.1E-I1 (<0.1%)

2.9E-10(<0.1%)

1.7E-06(64.3%)

95 %ile

2. 8E 07 (6.7%)

2.7E-08 (0.7%)

• 6.3E-1I ( < 0 - l % )

1. IE-09 ( < 0 . l % )

6.2EX»(0.1%)

1.5E-09«0.1%)

5.6E-07(I3.5-J(,)

O.OE+OO (0.0%)

6.5E-07(I5.8%)

I . 9 E - I O ( < O . I % )

I . 4 E - I O ( < 0 . 1 % )

I.6E-09 ( < 0 . 1 % )

8.7E-09(0.2%)

8.9E-08 (2.2%)

\ 2 E - I O ( < 0 \%)

I . .2E-09(<0.1%)

2-5E-06 (60.6%)

2.7E^)6 | 4. IE-06


Table 8bContaminant Contribution to Incremental Lifetime Cancer Risk - Future Adjacent Residential Scenario (a)

Chemical

Aroclor-1242

Aroclor-1248

Aroclor-1254

Arsenic

Benzo(a)pyrene

Benzo(b)fluoranthene

Benzene

Beryllium


Bromodichloromethane

Chloroform

Dibenzo(a,h)anthracene

Dieldrin

Methylene chloride

Pentachlorophenol

Tetrachloroethylene

Trichloroethylene

Vinyl chloride


50 %ileO.OE+00 (0.0%)

I.9E-I1 (0.2%)

O.OE+00 (0.0%)

4.3E-I1 (0.5%)

1.3E-1I (0.1%)

2.8E-12(<0.1%)

1.7E-09(18.3%)

O.OE+00 (00%)

1.5E-I1 (0.2%)

2 .5E- I3(<0 . ]%)

O.OE+00 (0.0%)

O.OE+00 (0.0%)

I.7E-09(I9.0%)

O.OE+00 (0.0%)

O.OE+00 (00%)

56E-09(6I 7%)

90 %ile

1. IE-07 (41.1%)

l.2E-08(46%)

O.OE+00 (0.0%)

5.0E-IO (02%)

2.3E-09 (0.9%)

5.7E-10(0.2%)

3.0E-08 (11.4%)

O.OE+00 (0.0%)

1 I E - I O < < 0 1%)

4.9E-1I (<0.l%)

4 5E 10(0.2%)

I.2E-14 ( < O I % )

4.8E-08 (18 3%)

4 . I E - I I (<0 .1%)

2.9E 10(0 1%)

6 IE-08 (230%)

95 %ile2.8E-07 (48.2%)

2.7E-08 (4.7%)

6.3E-11 (<0.1%)

I.I £-09(0.2%)

6.2E-09(1.1%)

1.5E-09<0.3%)

6.2E-08 (10.8%)

O.OE + 00 (0.0%)

1 9E-10(<O.I%)

1 4 E - I O ( < O . I % )

1 6E-09(0.3%)

2 5 E - I 2 ( < O . I % )

8.9E-08(L5.5%)

I .2E-10(<0 1%)

I.2E-09(0.2%)

1. IE-07 (18.6%)

Resident with un filtered /filtered outwash groundwater

50 %ile

O.OE+00 (0.0%)

1.9E-II (<0 1%)

O.OE+00 (00%)

4.3E-1I (<0.1%)

I .3E-II (<0.l%)

2.8E-I2(<0.1%)

1.7E-07(64.8%)

O.OE+00 (0.0%)

6.0E-08 (23.2%)

I.5E II (<0.1%)

2.2E-08 (86%)

2.5E-13(<0.1%)

O.OE+00 (0.0%)

I.3E09(0.5%)

1 7E-09(0.7%)

O.OE+00 (0.0%)

O.OE+00 (0.0%)

5.6E-09 (2.2%)

90%ileI.IE^)7(8.2%)

1.2E-08(0.9%)

O.OE+00 (0.0%)

5.0E-10(<0.1%)

2.3E-09 (0.2%)

5.7E-10(<0 1%)

6.3E^)7 (47.7%)

O.OE+00 (0.0%)

3.7E-07 (27.8%)

I .1E-10(<0 1%)

7.9E 08 (6.0%)

4.9E I I (<0 1%)

4.5E 10 (<0 1%)

9.5E 09 (0.7%)

4.8E-08 (3.7%)

4.1E-M (<0.1%)

2 9 E - I O ( < 0 1%)

6. IE-08 (4.6%)

95 %ile

2.8E-07(13.0%)

2.7E-08(I.3%)

6.3E-11 (<0 . l%)

1 IE-09 (<0. l%)

6.2E-09 (0.3%)

I.5E-09(<O.I%)

9.4E-07 (43.9%)

O.OE+00 (00%)

5.6E-07(263%)

1 . 9 E - I O ( < O . I % )

!. IE-07 (5.1%)

1 . 4 E - I O ( < 0 - i % )

1.6E-09 (<0 1%)

1.5E08(0.7%)

8.9E-08 (4.2%)

1 2 E - I O ( < 0 . 1 % )

I .2E-09<<0.1%)

1. IE-07 (5.0%)

Total 9. IE-09 26E-07 58E-07 2.6E-07 1.3E-06 2 I E 0 6



Table 9Contaminant Contribution to Incremental Lifetime Cancer Risk -

Occupational Scenario (a)

Chemical

Aroclor-1242

Aroclor-1248

Benzo(a)pyrene

Benzo(b)fluorantheneDieidrin

50 %ile

O.OE+00(0.0%)

O.OE+00(0.0%)

3.5E-11 (88.8%)

4.4E-12 (11.2%)

O.OE+00(0.0%)

90 %ile

4.9E-07 (90.6%)

4.0E-08(7.3%)

7.2E-09(1.3%)

9.4E-10(0.2%)

3.2E-09(0.6%)

95 %ile

1.0E-06(90.9%)

7.7E-08(6.8%)

1.6E-08(1.4%)

2.4E-09(0.2%)

9.2E-09(0.8%)

Total 3.9E-11 5.4E-07 1. IE-06




Table 10Contaminant Contribution -

Adjacent Residential Noncarcinogenic Scenario (a)

Chemical

4,4'-DDT

Acetone

Antimony

Arsenic

Bis(2-ethylhexyl)phthaiateBromodichloromethane

Cadmium

Chloroform

Dieldrin

Ethylbenzene

Fluor an thene

Pentachlorophenol

Phenanthrene

p,p'-Methoxychlor

PyreneTetrachloroethylene

Toluene

50 %ile

4.2E-09(<0.1%)

7.8E-11 (<0.1%)

O.OE+00 (0.0%)

2.7E-07 (0.4%)

2.6E-06 (3.4%)

3.8E-09(<0.1%)

O.OE+00 (0.0%)

9.4E-06(12.3%)

O.OE+00 (0.0%)

1.3E-06(1.7%)

2.3E-07 (0.3%)

4.8E-05 (63.2%)

1.9E-07 (0.2%)

O.OE+00 (0.0%)

1.4E-05(18.5%)

O.OE+00 (0.0%)

O.OE+00 (0.0%)

90 %ile

5.4E-06 (0.7%)

5.3E-07 (<0.1%)

O.OE+00 (0.0%)

7.3E-06(0.9%)

4.9E-05 (6.1%)

9.3E-08 (<0 .1%)

O.OE+00 (0.0%)

7.3E-05(9.1%)

2.5E-05(3.1%)

6.2E-05 (7.8%)

5.0E-06 (0.6%)

3.6E-04(44.9%)

4.2E-06 (0.5%)

1.8E-08(<0.1%)

1. IE-04 (14.2%)

6.7E-05(8.3%)

2.9E-05 (3.7%)

95 %ile

1.6E-05(1.I%)

2.6E-06(0.2%)

O.OE+00 (0.0%)

1.5E-05 (1.0%)

9.6E-05 (6.3%)

1.9E-07 «0.1%)

O.OE+00 (0.0%)

1. IE-04 (7. 2%)

1.2E-04 (7.9%)

1.4E-04(9.2%)

1. IE-05 (0.8%)

5.5E-04 (36.0%)

9.7E-06(0.6%)

I.5E-07(<0.1%)

1.8E-04(12.1%)

2.0E-04(13.1%)

6.9E-05(4.5%)

Total 7.6E-05 8.0E-04 1.5E-03



Table 11*Contaminant Contribution - Future Adjacent Residential Noocarcinogenic Scenario (•)

Chemical

1 ,2-Dichlorobcnzene

4,4' DOT

Acetone

Antimony

Arsenic

Bis(2-ethylhexyl)phlhaiate

Bromodichloromelhane

But y Ibe nzy Iphtha late

Cadmium

Chloroform

Chlo robe nzene

Copper

Di-n-buiylphthalaic

Dieldrm

Eihylbenzene

Fluoranthene

Pentac hlorophenoj

Phenanthrene

p .p '-Methoxychlor

Pyrene

Tetrachloroelhylene

Toluene

Resident using municipal groundwaler

SO %ile

4.2E-09(<O.I%)

7.8E-II<<0.1%)

O.OE+00(0.0%)

2.7E-07(0.4%)

2.6E-06(3.4%)

3.8E-09«0.1%)

O.OE+00(0.0%)

9.4E-06(I2.3%)

O.OE+00<0.0%)

l.3E-06(1.7%)

2.3E-07(0.3%)

4.8E-05 (63.2%)

1.9E-07(0.2%)

O.OE-t-00 (0.0%)

1.4E-05(I8.5%)

O.OE+00(0.0%)

O.OE+00(0.0%)

90 %ile

5.4E-06<0.7%)

5.3E-07«0.1%)

O.OE+00(0.0%)

7-3E-06(0.9%)

4.9E-05(6.l%)

9.3E-08(<0.1%)

O.OE+00(0.0%)

7.3E-05(9-I%)

2.5E-05(3.I3)

6.2E-05(7.8»)

5-OE-06(0.6%)

3-6E-04{44.9%)

4-2E-06(0.5%)

|.8E-08(<O.I%)

1. IE-04 (14. 2%)

6-7E-05(8.3%)

2-9E-05(3.7%)

Total 7.6E-05 8 OEM

95 %ik

I.6E-05(I.1%)

2.6E-06(0.2%)

O.OE+00(0.0%)

I.5E-05(1-0%)

9.6E-05(6.3%)

I.9E-07«0.1%)

O.OE+00(0.0%)

1. IE-04 (7.2%)

l.2E-04(7.9%)

1.4E-04(9.2%)

I. IE-05 (0.8%)

5.5E-04(36.0%)

9.7E-06 (0.6%)

I.5E-07«0.1%)

I.8E-04(I2.1%)

2.0E-04(I3.I%)

6.9E-05(4.5%)

Resident with unfiltered/filtcrcd shallow groundwater

50 %ile

2.4E-04(3.6%)

4.2E-09«O.I%)

3.8E-05(0.6%)

O.OE + 00(0.0%)

2.7E-07(<O.I%)

4.7E-03(70.9%)

3.8E-09(<O.I%)

73E-05(I.1%)

O.OE+00(0.0%)

94E^)6(0.1%)

7.4E-04(1I.2%)

4.0E-04(6.0%)

3.7E-04(5.5%)

O.OE + 00(0.0%)

1 3E-06«0.1%)

23E-07(<0.1%)

4.8E^)5 (0.7%)

1.9E-07(<O.I%)

O.OE+00(0.0%)

1 4E-05(0.2%)

O.OE + 00(0.0%)

O.OE+00(0.0%)

1 5E-03 6.6E-03

90 Kile

8.6E-04(3.4%)

5.4E-06(<O.I%)

4.3E-04(1.7%)

0,OE+00(0.0%)

7.3E-06(<O.I%)

1.6E-02(63.0%)

9.3E-08(<O.I%)

2.4E-04(I.O%)

O.OE+00 (0.0%)

7.3E-05(0.3%)

2.5E-03(I0.1%)

3.3E-03 (13.0%)

I.2E-03(4.8%)

2.5E-05(<0 \%)

6.2E-05(0.2%)

5.0E-06(<0.1%)

3.6E-04(I.4%)

4.2E-06(<O.I%)

I.8E-08«O.I%)

1. IE-04 (0.5%)

6.7E-05(OJ%)

2.9E-05(0.l%)

2-5E-02

95 %ile

I.2E-03(3.5'*)

I .6E-05(<O.I%)

7.6E-04(2.3%)

O.OE + 00(0.0%)

1.5E-05(<O.I%)

2.0E-02(59.2%)

I.9E-07(<0.1%)

3.0E-04(0.9%)

O.OE + 00(0.0*)

I.I £-04(0.3%)

3.2E-03(9.4%)

5.4E-03(16.0%)

I.5E-03(4.5'A)

1 2E-04(0.4«)

1 4E-04(0.4^)

1. IE-OS «0.l%)

5.5E-04(1.6%)

9.7E-06«0.l%)

I.5E-07«O.I%)

I.8E-04(0.5%)

2 OE 04 (0.6%)

6.9E-05(0.2%)

3.4E-02


Table I IbConuminant Contribution - Future Adjacent Residential Noncan:inogenic Scenario (a)

Chemical

4.4' DOT

Acetone

Antimony

Arsenic

Bis(2'elhylhexyl)phlh»Uie

Bromod ic hlorometha ne

Buly Ibe nzy Iphlhalale

Cadmium

Chloroform

Di -n-buly Iphlhalate

Dieldrin

Eihyl benzene

Fluoranlhenc

Mclhyleno chloride

Pe nlai'hlorophenol

Phenanthrene

p.p'-Methoxychlor

Pyrcne

Tetrachloroelhylene

Toluene


50 %il*

4.2E-09(<O.I%)

7.8E-M ( < O . L % >

O.OE + 00(0.0%)

2.7E-07(0.4%)

2.6E-06<3.4%)

3.8E-09(<0.1%)

O.OE + 00(0,0%)

9.4E-06(12.3%>

O.OE + 00(0.0%)

1.3E-06(I.7%)

2.3E-07(OJK)

4.8E-05 (63.2%)

1.9E-07(0.2%)

O.OE + 00(0,0%)

I.4E-OMIS.5*)

O.OE + 00(0.0%)

O.OE + 00{O.OS.)

90 Kile

5-4E-06(0.7»)

.S.3E07(<O.I»)

O.OE + 00(0.0%)

7.3E-06(0.9*>

4.9E-05(6.1%)

9.3E-08(<0.1%)

O.OE + 00(0.0%)

7.3E-05(9.I*>

2.5E-05(J.[ft)

6 .2EOS(7.8 '^)

5.0E-06((I.6!()

3.6E-04(44.9%)

4.2E-06(0.59t)

I.8E-08«O.I%)

I . I E - 0 4 ( I 4 . 2 % )

6.7E-O.S(8.35E)

2 9E-OS(3.7«)

95 %ile

I.6E-05(1.I%)

2.6E-06(0.2%)

O.OE+00(0.0%)

|.5E-OS(I.O%)

9.6E-05(6.3%)

1.9E-07(<0.1%>

O.OE+00(0.0%)

L1E-04(7.2%)

1 2E-04(7.9%)

I-4E-04(9.2%)

l-lE-05(0.8-«.)

5.5E-04(36.0%)

9.7E-06(0.6%)

1.5E-07(<O.I%)

|.8E-04(I2.1%)

2.0E-04(13.l*)

6.9E-05(4.5%)

Resident with unfiltered/filiered outwash ^roundwater

50 %i\e

4.2E-09(<O.I»)

7.8E-II ( < O . I K )

O.OE+00(0.0%)

2.7E-07(<0.1%)

3.5E-03(33.6%)

3.8E-09(<O.I*)

7.6E-05(0.7%)

O.OE+00{0.0%)

2.6E-03<25.0%)

4.0E-03 (38.3%)

O.OE+00<0.0%)

I.3E-06«0.1%)

2.3E-07{<0.1%)

l.9E04(1.8%)

4.8E-05(0-5%)

1.9E-07(<0.1%)

O.OE+00{0.0%)

I.4E-05(0.1%)

O.OE + 00(0.0%)

O.OE + 00<0.0%)

90 'i.lc

S.4E-06(<0.)%)

2. IE-02 (40.9*)

O.OE + 00(0.0%)

7.3E-06«O.I%)

9.6E-03(|g.4%)

9.3E-08(<O.I%)

2.8E-04(O.S%)

O.OE+00(0.0%)

6.2E-03(I1.8%)

I.4E-02(25.9»)

2.5E-05(<O.I%)

6.2E-OMO.)',O

5.1>E-06(<0 1%)

6 1E-04(I 29f)

3.6E-04(0.7«)

4.2E-06«O.I%)

1.8E-08(<0 1'*)

1. IE-04 (0.2%)

6 .7E-05(O. I%)

2 .9E-05(<O.I 'A)

95 %ile

1.6E-05«0 I S J )

3 .IE-02 (44JW)

O.OE-t-OO(O.O^)

I.SE-05«O.I%)

1.2E-02(I7.1%)

l.9E-07(<0 1%)

3.6E-04(O.S%)

O.OE + 00(0.0%)

7.5E-03(l0.6'i)

l.7E-02(24.5'^)

1.2E-04(0.2!I)

1 4 E - 0 4 ( ( ) 2 y > "

1.1 EOS ( < , ( ) \'4)

r*8.{)E-04(l.l%)

^.5E-04(0.85)

9.7E-06(<O.I*)

I .5E-07«O.I%>

I.8E-04(0.3%)

2.0E-04(OJ«)

6.9E-05«O.I%)

Total 7.6E-05 8.0E-O4 1 .5E-03 1 .OE-02 5.2E-02 7. IE-02

(a) Number in parentheses is percent contribution to total risk


Table 12Contaminant Contribution -

Occupational Noncarcinogenic Scenario

Chemical

4,4'-DDT


Dieldrin

Fluoramhene

Phenanthrenep,p'-Methoxychlor

Pyrene

50 %ile

4.0E-09 (4.4%)

3.7E-08(41.4%)

O.OE+00 (0.0%)

1.4E-08 (15.595)

2. IE-08 (23.2%)

O.OE+00 (0.0%)

1.4E-08(15.5%)

90 %ile

9.9E-07(19.3%)

2.7E-07(5.2%)

3.4E-06(65.1%)

1.5E-07(3.0%)

2. IE-07 (4.1%)

2.6E-08(0.5%)

1.4E-07 (2.7%)

95 %ile

2.3E-06(15.9%)

4.4E-07(3.1%)

1. IE-05 (73.1%)

2.8E-07(1.9%)

3.9E-07(2.7%)

2.4E-07 ( t .6%)

2.4E-07 (1.7%)

Total 9.0E-08 5. IE-06 1.4E-05



Chemical

Table 13

Stochastic EH Is for Red Wing Blackbird

IngeMion of Plains

50% 90%

Ingeslion of Insects

50 % 90 % 95

Incidental Ingest ion of Soil

50 % 90 % 95 %

Injio l̂ion of Surface Water

50 % 90 % 95

Aroclor-1242

Aroclor-1248

Aroc lor- 1254

Acenaphtfiene

Anthracene

Benzo{a)anlhrace IK

Benzo(a)pyrene

Be nzo(b ) flu ora nlhe ne

Benzo(g.h,i)perykne

Be nzn( k ) fl uora nlh re nc

Chrysene

Dibenzo(a.h)anlhrat:ene

Dielilrin

Fluorene

lndeno(1.2.3-cd)-pyrene

Lead

Acetone

Cyanide

Zinc

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.0 1

< 0.01

< 0.01

< 0.01

0.03

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

0.05

< 0.01

< 0.01

«; ooi< 001

< 001

< 001

< 0.01

< 0.01

<: 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

0.06

0.05

0.02

< 0.01

< 0.01

0.01

0.03

0.03

0.07

0.02

0.07

0.03

< 0.01

< ooi< 0.01

0.01

0.24

0.22

0.18

< 0.01

0.01

0.02

0.06

0.07

0.17

0.04

0.17

0.08

0.01

< 0.01

0.0 1

0.04

0.48

0.28

0.21

< 0.01

0.01

0.03

0.08

0.09

0.21

0.05

0.21

0.10

0.02

< 0.01

0.01

0.05

0.57

0.06

0.03

< 0.01

< 0.01

0.02

0.04

0.04

0.10

0.03

0.09

0.05

0.01

< OOI

0.01

0.02

0.34

0.27

0.22

< 0.01

0.01

0.03

0.08

0.09

0.22

0.05

0.21

0.10

0.02

< 0.01

0.01

0.05

0.61

0.35

0.26

0.01

0.01

0.03

0.09

O.M

0.25

0.05

0.25

0.12

0.02

< OOI

0.02

0.06

0.68

< OOI 0.02 008

0.09 ' 0 13 n 14

< OOI 002 002

PATHWAY TOTAL 0.03 0.07 n 118 060 1.57 I 91 0.84 1.97 232 0.09 0 .17 H 2 4

Chemical

Table 14

Stochattu; EHls for Mink

I age M ion of Insect

50% 90%

Incidental Ingeslion of Soil

50 % 90 % 95 %

Ingevlion of Terrestrial Animal*

50% 90 % 95 %

Aroclor-1242

Aroc lor- 1248

Aroclor-1254

Acenaphthene

Anthracene

Benzo(a)anihraceiK

Benzo<a)pyrenc

Be nzo(b)fluoranthene

Benzo(g,h , i)pery Icnc

Benzo(k)fluonmthrene

Chryscne

D ibe nzo<a . h )a nth rac e ne

Dieldrin

Fluorene

lndeno( 1 ,2,3-cd)-py«ne

Lead

0.02

< 0 01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 001

< 0.01

< 0.01

0.23

0.09

0.07

< 0.01

< 0.01

< 0.01

< 0.01

< 001

0.02

< 0.01

002

0.01

< 0.01

< 0.01

< 0.01

< 0.01

0.51

0.12

0.09

0.02

< 0.01

< 0.01

0.01

0.01

0.03

< 0.01

0.03

0.01

< 0.01

< 0.01

< 0.0 1

< 0.01

061

0.03

0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

0.01

< 0.01

0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

0.32

0.11

0.08

< 0.01

< 0.01

< 0.01

< 0.01

0.01

0.03

< 0.01

0.03

0.01

< 0.01

< 0.01

< 0.01

< 0.0 1

0.58

0.15

0.10

0.03

< 0.01

< 0.01

0.01

0.01

0.03

< 0 01

0.03

002

< 0.01

< 0.01

< 0.01

< 0.01

0.66

0.02

0.05

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

0.23

0.11

0.37

< 0.01

< 0.01

< 0.01

< 0.01

< 0.01

0.02

< 0.01

0.02

0.01

< 0.01

< 0.01

< 0.01

< 0.01

0.52

0.15

0.47

0.32

< 0.01

< 0.01

0.01

0.01

0.03

< 0.01

0.03

0.01

< 0.01

< 0.01

< 0 01

< 0.01

0.62

PATHWAY TOTAL 0.29 0.77 0.96 0.40 0.88 1.06 0.33 1.68

c

ContaminantSources

ReleaseMechanisms

TransportMedia

ExposureRoutes

Receptors

Yeoman/EdwardsLandfills

Leaching

Wind Erosion

Diffusion /(Soil Gas)

Surface Water

Air

Residents

Ingestion ——————/• Groundwater (residents). Soil (residents and workers)\. Surface Water (residents). Sediments (residents)

^Inhalation - - - - - - - - —• Groundwater (residents). Soil Gas (residents)

Dermal Contact —— - i-»> Site Workers• Groundwater (residents)• Surface Water (residents)• Soil (residents and workers)« Sediments (residents)

Explanation——> Current & Future Adjacent Residential or Site Worker Scenarios

- •*> Minor Contributor to Exposure• - - > Future Groundwater Use Scenario Only

FIGURE 2-1CONCEPTUAL PATHWAY MODEL FOR HUMAN EXPOSURE

YEOMAN/EDWARDS LANDFILL ASSESSMENT/IL

Contaminant Release Transport Exposure ReceptorsSources Mechanisms Media Routes

Yeoman/Edwards . ^ .——— ——»> Leaching ^ ——»> Groundwater — > Immersion —--- ---> Aquatic CommunityLandfills A *i /

* (Waukegan River)

* Surface Water(Yeoman Creek)

FIGURE 2-2CONCEPTUAL PATHWAY MODEL FOR

AQUATIC ECOLOGICAL EXPOSUREf YEOMAN/EDWARDS LANDFILL ASSESSMENT/IL

r

ContaminantSources

ReleaseMechanisms

TransportMedia

ExposureRoutes

Receptors

Yeoman/EdwardsLandfills

Leaching

Wind Erosion

Groundwater

Surface Water

Ingestion

Red-Winged* Blackbird*

Mink*

Explanation______ _>, Current & Future

Indicator Species

FIGURE 2-3aCONCEPTUAL PATHWAY MODEL FOR

TERRESTRIAL ECOLOGICAL EXPOSUREYEOMAN/EDWARDS LANDFILL ASSESSMEN1/IL

Soil & Surface —Water Sediments

Plants Insects Red-WingedBlackbird

2-3bFIGURE

CONCEPTUAL FOOD CHAIN FOR THERED-WINGED BLACKBIRD

YEOMAN/EDWARDS LANDFILL ASSESSMENT/tL

ifc kaiser stochastic risk assessment: vol 1 of 2 (text ... · this stochastic human health and...

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