redacted clement intl corp - technical ...background concentrations from the ri for surface soil,...

TECHNICAL MEMORANDUM NO. 4

I

IBASELINE RISK ASSESSMENT VORKFLAN FOR THE

I CITY DISPOSAL LANDFILLDUNN, WISCONSIN

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I" ________________________________| ______________________dement International Corporation

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environmental and Health Science

TECHNICAL MEMORANDUM NO. 4

BASELINE RISK ASSESSMENT WORKPLAN FOR THECITY DISPOSAL LANDFILL

DUNN, WISCONSIN

Prepared for:

Waste Management of North America, Inc.Midwest RegionP.O. Box 7070

Westchester, Illinois 60154

Prepared by:

Clement International Corp.9300 Lee Highway

Fairfax, Virginia 22031

July 1, 1991

TABLE OF CONTENTS

1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.0 IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN . . . . . . . . . . 1

2.1 Surface Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.1.1 Data Summary . . . . . . . . . . . . . . . . . . . . . . . . 102.1.2 Selection of Chemicals of Potential Concern for Surface

Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.2 Subsurface Soils . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.2.1 Data Summary . . . . . . . . . . . . . . . . . . . . . . . . 172.2.2 Selection of Chemicals of Potential Concern for Subsurface

Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.3 Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.3.1 Data Summary . . . . . . . . . . . . . . . . . . . . . . . . 202.3.2 Selection of Chemicals of Potential Concern for Groundwater . 30

2.3.2.1 Shallow and Intermediate (S&I) Groundwater . . . . . 302.3.2.2 Groundwater in Bedrock . . . . . . . . . . . . . . . 312.3.2.3 Residential Wells . . . . . . . . . . . . . . . . . 32

2.4 Summary of Chemicals of Potential Concern . . . . . . . . . . . . . 34

3.0 TOXICITY ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . . 34

4.0 HUMAN EXPOSURE ASSESSMENT . . . . . . . . . . . . . . . . . . . . . 344.1 Site Characterization . . . . . . . . . . . . . . . . . . . . . . . 394.2 Identification of Exposure Pathways . . . . . . . . . . . . . . . . 394.3 Quantification of Exposure Point Concentrations . . . . . . . . . . 444.4 Estimation of Chemical Intakes . . . . . . . . . . . . . . . . . . . 45

5.0 RISK CHARACTERIZATION . . . . . . . . . . . . . . . . . . . . . . . 57

6.0 ECOLOGICAL RISK ASSESSMENT . . . . . . . . . . . . . . . . . . . . . 57

7.0 DISCUSSION OF UNCERTAINTIES . . . . . . . . . . . . . . . . . . . . 58

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

1.0 INTRODUCTION

This technical workplan outlines the general methodology that will beapplied Co estimate the potential health risks associated with exposures tochemicals originating from the City Disposal Landfill (Dunn, Wisconsin). Ingeneral, the risk assessment will be consistent with relevant guidance andstandards developed by the United States Environmental Protection Agency

(USEPA 1986a,b,c, 1989a,b,c, 1991a). To date, no separate guidance has beenprovided by the Wisconsin Department of Natural Resources (WDNR).

The purpose of the technical workplan is to allow USEPA Region V andWisconsin DNR the opportunity to provide comments on the approach proposed forthe City Disposal Landfill Baseline Risk Assessment (RA) before the work iscompleted. It should be noted, however, that portions of this workplanalready reflect comments received from USEPA Region V (USEPA 1991b,c) on aworkplan for another Waste Management of North America, Inc. (WMNA) site(Clement 1991). The comments required that only a reasonable maximum exposure(RME) scenario be evaluated in the main text of the Baseline RA. It wasagreed at a meeting with USEPA Region V1 that an average case scenario couldbe presented in the uncertainty section of the document. Additionally, anumber of specific parameter values to be used in estimating exposures wereprovided by USEPA Region V. Accordingly, the current technical workplan forCity Disposal has incorporated the comments provided in USEPA (1991b,c). The

inclusion of approaches and values required by USEPA Region V should not beconstrued, however, to imply any verification or concurrence on the part ofWaste Management of North America, Inc. or Clement International Corporation.

2.0 IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN

The purpose of selecting chemicals of potential concern for the riskassessment is to identify those chemicals present at the site that will be the

focus of the risk assessment. Prior to selecting chemicals of potential

Personal communication with P. Van Leeuwen, USEPA Region V. June 4,1991.

concern, the first step is to summarize all available Remedial Investigation(RI) data according to the following procedures which are in generalaccordance with USEPA (1989a):

• RI data collected and analyzed according to USEPA's ContractLaboratory Program (CLP) procedures are used in the selection ofchemicals of concern for this assessment.

• In order to select potential chemicals of concern, the RI datawere divided into groups which describe environmental conditionsrelevant to the baseline risk assessment (e.g., groundwater,soil). For example, a group of background data will be used todetermine if concentrations of chemicals detected on ordowngradient of the site are at naturally occurring levels.Grouping data also helps in determining exposure pointconcentrations for target populations and in assisting in theidentification of areas potentially requiring remediation. Thesegroups will be described in full detail by environmental medium inSections 2.1 through 2.5. Data summarized by environmental medium(e.g., groundwater, soil) are grouped within that medium todescribe conditions relevant to the risk assessment.

• Concentration data from multiple samples from the same samplelocation taken at different times are averaged. If a chemical wasdetected in one or more sampling rounds and not in others at aparticular sample location, the average concentration for thesample location is calculated by averaging the detectedconcentration(s) with one-half of the detection limit of the non-detected concentration^). Duplicate samples for a given samplingpoint are also treated in this manner.

• Due to the fact that there are varying chemical- and sample-specific detection limits, even within one medium, samples inwhich a chemical is not detected are compared to the maximumdetected concentration for that chemical to determine if the non-detects will be included in calculating the mean concentrations.If the detection limit for a sample in which a chemical was notdetected is two or more times higher than the maximum detectedconcentration in that medium, the sample is not included in thecalculation of the average for that chemical. This is done toprevent the average from being artificially biased upwards by highdetection limits. CLP detection limits were used for all non-detects which did not have a sample-specific detection limit.

For the purposes of this assessment, the "site" has been defined toconsist of all landfill cells (1 through 12). Also, the plot of land whichcan be defined by the extension of the northern and southern boundaries ofCell 12 to Badfish Creek is also considered to be a section of the site

because site-related chemicals have been measured in groundwater at piezometerPZ-11 in this area. Figure 1 shows the boundaries of the City DisposalLandfill site.

The summarized chemical data is presented by medium and consists ofparameters such as the frequency of detection, the arithmetic meanconcentration, and the range of detected concentrations. Tables which presentthe summarized data are referred to for the selection of chemicals ofpotential concern for surface soil, subsurface soil, shallow and intermediate

. (S&I) groundwater (in glacial materials), groundwater in bedrock, andresidential wells for the City Disposal Landfill.

The procedures used for the selection of chemicals of potential concernfor the site are described below. The purpose of selecting chemicals ofpotential concern is to eliminate from the risk assessment: (1) thosechemicals that are associated with sampling or laboratory artifacts; and (2)those chemicals existing at or below naturally occurring levels at the site.In this document, chemicals of potential concern have been selected based onan analysis of the summarized data and a certain protocol (described below).However, as described below, WMNA reserves the right to re-evaluate theselection of chemicals pending selection of a more appropriate statistical

"̂"̂ approach.

It is important to recognize that the selection of a chemical as achemical of potential concern does not necessarily indicate that it poses aproblem. The selection of a chemical only indicates that there is a need toevaluate that chemical in the Baseline RA to determine if the chemical willresult in potential health risks.

The following methodology is used in selecting chemicals of potentialconcern from the summarized data:

• According to USEPA (1989a) guidance, inorganic chemicals presentat the site at naturally occurring levels may be eliminated fromthe quantitative risk assessment. According to this guidance, astatistical method should be used to determine whether chemical

FIGURE 1

SITE BOUNDARY (a)CITY DISPOSAL LANDFILL

IM Ml*)

l (••>*-••">

(a) The site boundary is outlined The 'site' is defined by landfill ceHs 1 through 12. Also, the plot of land which can be defined by theextension of the northern and southern boundaries of ceH 1- Badfish Creek is also considered to be a spction of the site.sp

concentrations detected at the site are within, or elevated above,background levels. This approach was used to evaluate backgroundconcentrations for those sample groupings where a sufficientnumber of samples (at least three upgradient and threedowngradient) is available. The statistical method that is usedshould be appropriate for the data under evaluation and shouldaccount for data below the limit of detection (USEPA 1988a). Forthis assessment, the Cochran's approximation to the Behran's-Fisher Student's t-test (CABF) was used; however, statisticaltheory and the available guidance from USEPA on this topic (e.g.,USEPA 1989a,b, 1988a,b,c) will be re-examined to verify whetherthe CABF test is the most appropriate statistical test. As aresult, the list of selected chemicals may change somewhat if adifferent statistical test is determined to be more appropriatethan the CABF and a different set of statistically significantchemical constituents results from the comparison of backgroundversus potentially site-affected samples. Justification will beprovided in the Baseline RA to support the use of any alternativestatistical test.

If a sufficient number of samples is not available for a standardstatistical test, alternative statistical methods will beconsidered along with guidance received from USEPA Region V.Using an alternative statistical method, for example, if thecentral tendency (for a parametric test) or rank ordering (for anonparametrie test) of chemical concentrations in potentiallysite-affected samples significantly exceed those of backgroundsamples, then the chemical would be considered site-related andincluded in the Baseline RA. Using the approach suggested byUSEPA Region V2, if the maximum chemical concentration in apotentially site-affected medium is higher than the maximumconcentration in the background, the chemical would be consideredto be site-related. It should be noted that standard riskassessment practice uses a multiplier of two to five on thebackground data in conducting this comparison. For thisassessment, however, the approach required by USEPA Region V wasused. If an alternative test is determined to be more appropriatethan this approach, justification will be provided in the BaselineRA and the list of selected chemicals may change slightly. Whenrelevant background data are not available for a specificchemical, the chemical will be conservatively selected as achemical of potential concern. Background concentrations from theRI for surface soil, subsurface soil, shallow and intermediate(S&I) groundwater, and groundwater in bedrock are presented inTables 1, 2, 3, and 4. In addition, regional background data forgroundwater and soil were used to supplement the RI backgrounddata when less than three RI background samples were available.These data are summarized later in this section in Tables 2 and 3.

2Personal communication with E. Moran, USEPA Region V. May 22, 1991.

5

TABLE 1

SUMMARY OF CHEMICALS DETECTED IN BACKGROUND GROUNDUATER SAMPLESAT CITY DISPOSAL LANDFILL

SHALLOW AND INTERMEDIATE WELLS (a)(Concentrations reported in ug/L)

Frequency of Arithmetic Range of DetectedChemical Detection (b) Mean Background Concentrations

Organ!cs:

Acetone 6/7 7.7 5.7 - 13.4Methylene Chloride 4/7 3.1 1.7-5Trichloroethene 1/7 1.4 1.4

Inorganics:

AmmoniaArsenicBariumBoronCalciumChlorideCyanideFluorideIronMagnesiumManganeseNickelNitratePotassiumSodiumSulfateZinc

1 / 41 / 22 / 24/47/77/73 / 37 / 74/77/77/71 / 21 / 46/77/76/72 / 2

1004.39156

78,00018,000

1.52,200130

42,0001102.4100

2,0005,90023,000

19

2008.2

71 - 11028 - 89

68,000 - 93,0004,400 - 35,900

1.3 - 1.6100 - 50093 - 440

33,000 - 55,20017 - 4504.3300

1,500 • 4,1003,000 - 9,60012,000 - 50,000

19

NA = Not Applicable, since there was only one sample.(a) Background consists of shallow and intermediate grounduater samples PZ-10,

PZ-14, PZ-15, P-7A, P-9A, B-14RR, and B-17RR.(b) The number of samples in which the contaminant was detected divided by the

total number of samples analyzed.

TABLE 2

SUMMARY OF CHEMICALS DETECTED IN BACKGROUND GROUNDUATER SAMPLESAT CITY DISPOSAL LANDFILL

BEDROCK WELLS (a)(Concentrations reported in ug/L)

ChemicalFrequency ofDetection (b)

Range ofBackground Concentrations

Frequency ofDetection

Range ofBackg round Concent ra t ionsIn Dane County Wells (c)

Organics:Methylene Chloride 1 / 1

Inorganics:Barium 1 / 1Boron 1 / 1Calcium 1 / 1Chloride 1 /Cyanide 1 /Fluoride 1 /Iron NAMagnesium 1 /Manganese 1 /Nitrate 1 /Potassium 1 /Sodium 1 /Sulfate 1 /Zinc 1 /

8.2

11040

79,85045,500

0.6100NA

40,6001.5

8,7001,80019,50025,700

16

NANANANANANANANANANANANANANA

NANA

22,000 - 103,0000 - 78,000

NA0 - 5000 - 6,600

9,000 - 65,0000 - 320

NA1,300 - 2,6001,500 - 10,000

0 - 177,000NA

NA = Data not available.

(a) Background consists of bedrock groundwater sample P-2A.(b) The number of samples in which the contaminant was detected divided by the total number of samples

analyzed.(c) Information obtained from Cline (1965).

TABLE 3

SUMMARY OF CHEMICALS DETECTED IN BACKGROUND SURFACE SOIL SAMPLESAT CITY DISPOSAL LANDFILL (a)

(Concentrations reported in ug/kg)

ChemicalFrequency ofDetection (b)

Range ofBackground

ConcentrationsFrequency ofDetection

Range of U.S.G.SBackground

Concentrations (c)

Organics:Methylene Chloride

Inorganics:1 / 1 18.3

AluminumAntimonyArsenicBariumBerylliumCadmiumCalciumChromiumCobaltCopperCyanideIronLeadMagnesiumManganeseMercuryNickelPotassiumSeleniumVanadiumZinc

/ 1 7,360,000/ 1 3,900NA NA/ 130,000/ 380/ 790/ 1,800,000/ 10,000/ 1 2,400/ 1 14,000/ 1 70/ 1 3,900,000/ 1 11,000/ 1 950,000/ 1 147,000NA NA

1 / 1 8,7001 / 1 550,0001 / 1 3501 / 1 8,0001 / 1 34,000

NANA3/33/31/3NA3/33/33/33/3NA3/33/33/33/33/33/33/33/33/33/3

6.500.

5.500,50,7,

10,000,

2,000,500,

15,18,000,

30.

NANA

800 - 9.900000 - 1,000,0003,000

NA000 - 5,600,000000 - 100,000000 - 10,00010,000

NA000 - 30,000,00015.000000 - 7,000,000000 - 1,000,00070 - 220000 - 50,000000 - 23,000,000300 •- 600000 - 100,00050.000

NA = Data not available.(a) Background consists of surface soil sample SO-1.(b) The number of samples in which the contaminant was detected divided by the total number of

samples analyzed.(c) Taken from Boerngen and Shacklette (1981). Background concentrations based on those samples

taken in counties within 50 miles of the site (includes one sample in each of thefollowing counties: Dane, Green and Rock).

TABLE 4

SUMMARY OF CHEMICALS DETECTED IN BACKGROUND SUBSURFACE SOIL SAMPLESAT CITY DISPOSAL LANDFILL (a)


Frequency ofChemical Detection (b)

Organics:

Acetonebis(2-Ethylhexyl)phthalateIsophoroneMethylene ChlorideToluene

2/21 / 21 / 22 / 21 / 2

ArithmeticMean

151709308.81.7

Range ofBackground Concentrations

12.5 - 17.2168.59328 • 9.51.7

Inorganics:AluminumArsenicBariumBerylliumBoronCadmiumCalciumChromiumCobaltCopperCyanideIronLeadMagnesiumManganeseNickelPotassiumSodiumVanadiumZinc

2/22/22/22/21 / 11 / 22/ 22/22/ 22/ 21 / 22/22 / 22/22 / 22/22/22/22/22/2

940,0001,70012,000

88NA480

28,000,0005,0001,9009,000280

3,500,0002)300

14,000,000310,0005,500

430,00088,0006,10027,000

910,000 - 970,000915 • 2,400

4,300 - 19,00076.3 - 10010,750

7356,345,000 - 48,800,000

4,000 • 5,9001,227.5 - 2,6008,650 - 9,400

3002,500,000 • 4,450,000

1,120 - 3,4001,910,000 - 26,700,000189,000 - 426.5004,300 - 6.650

362,000 • 495,00067,000 • 110,0005,650 - 6,50021,000 • 33,500

NA * Not applicable, since there was only one sample.(a) Background consists of subsurface soil samples P-2A and SB-15.(b) The number of samples in which the contaminant was detected divided by the total number

of samples analyzed.

• Site data are compared to available blank (laboratory, field, andtrip) data as recommended in USEPA (1989a). The blank data (fieldand trip) for the groundwater in bedrock, I&S groundwater andresidential well groundwater groups is presented in Table 5.Laboratory blank data are presented in Table 6. According toUSEPA (1989a), if the detected concentration in a sample is lessthan 10 times the blank concentration for common laboratorycontaminants (acetone, 2-butanone, methylene chloride, toluene,and the phthalate esters) the chemical is not selected forevaluation in the risk assessment. For those organic or inorganicchemicals that are not considered by USEPA to be common laboratorycontaminants (all other compounds), if the detected concentrationis less than 5 times the maximum detected concentration in theblanks, the chemical is not selected for evaluation in the riskassessment.

• Additionally, carcinogenic and noncarcinogenic polycyclic aromatichydrocarbons (PAHs) will be compared to "background" levels insoils. PAHs are generally ubiquitous in the environment. Theyare emitted by all combustion sources including burning of coal,oil, refuse, and diesel fuel. Other sources of PAHs includeleaching from coal storage piles, creosote treated lumber andasphalt surfaces. Table 7 presents the results of an in-depthliterature review of PAH levels in soils which are considered tobe representative of "background" levels in soils in various landuse areas.

The following sections describe the data groupings for the City DisposalLandfill baseline risk assessment and the selection of the chemicals ofpotential concern within each of these sampling groups.

2.1 Surface Soils

2.1.1 Data Summary

Thirteen surface soil samples were collected on site and in surroundingareas, six of which are directly on top of the filled area of the landfill.These samples are grouped into three categories. The Background groupcontains a sample which is to the north of the site. This sampling locationis upgradient of the site (with respect to potential surface water runoff) andis considered not to have been affected by the site. The second group of data

represents sampling locations off site which could potentially be impacted by

chemical migration from the site. These were grouped into the Off Sice

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TABLE 5

SUMMARY OF CHEMICALS DETECTED IN BLANK GROUNDWATER SAMPLESAT CITY DISPOSAL LANDFILL

(Concentrations reported in ug/L)

Frequency ofChemical Detection (a)

BEDROCK WELLS

Field Blank:

Organics:AcetoneBenzeneChloroformMethylene ChlorideToluene

Trip Blank:

Organics:Acetone

INTERMEDIATE & SHALLOW WELLS

Field BlankOrganics:AcetoneMethylene ChlorideTetrahydrofuran

Inorganics:AluminumBoronCalciumChlorideCopperCyanideLeadMagnesiumManganeseSodiumSulfateZinc

Trip Blank

Organics:AcetoneMethylene ChlorideToluene

2/21 / 11 / 12 / 21 / 1

1 / 1

5/66/61 / 6

1 / 13 / 31 / 41 / 61 / 13/31 / 11 / 41 / 41 / 41 / 51 / 1

4 / 73 / 71 / 7

CLPRange of Detected DetectionBlank Concentrations Limits

2.9 - 7.30.72

5.3 - 6.50.9

24.7

5 - 8.72.5 - 16.414.4

3428 - 150720

1,0006.8

0.1 - 1.81.1364.6680

6,10032

3.0 - 9.13.6 • 10.0

5.5

105555

10

10 .5

NA

200NA

5,000NA25103

5,00015

5,000NA20

1055

RESIDENTIAL WELLS

Trip Blank

Organics:Acetone

Field Blank

Organics:Methylene Chloride

Inorganics:BoronChlorideCyanideFluoride

1 / 1

1 / 1

1 / 11 / 11 / 11 / 1

3.2

7.8

1501,0000.2100

10

5

NANA10NA

NA 3 Not available.(a) The number of samples in which the contaminant was detected divided by the total

number of samples analyzed.11

TABLE 6

SUMMARY OF CHEMICALS DETECTED IN LABORATORY BLANK SAMPLES(Concentrations reported in ug/L)

Chemical

AcetoneMethyl Ethyl KetoneMethylene ChlorideToluene

Frequency ofDetection (a)

21 / 4041 / 501

147 / 45324 / 452

Range of DetectedBlank Concentrations

3.4 - 19.918.8

0.3 - 14.90.2 - 3.6

(a) The number of samples in which the contaminant was detected divided bythe total number of samples analyzed.

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TABLE 7

BACKGROUND SOIL CONCENTRATIONS OF TARGET COMPOUND LISTPOLYCYCL1C AROMATIC HYDROCARBONS (PAHS)

Concentration (ug/kg)

Rural Soil Agricultural Soil Urban Soil

Carcinogenic PAHs

Benzo(a)anthracene CB2]Benzo(b)fluoranthene CB2]Benzo(j)fIuorantheneBenzo(b+ j)fIuorantheneBenzo(k)fluoranthene CB2]Benzo(a)pyrene CB2]Chrysene CB2]Dibenzo(a,h)anthracene CB2]Indeno(1,2,3-cd)pyrene CB2]

5 - 2020 - 30

25 - 11010 - 1102 - 1,30038.32.3

10 - 15

56 - 11058 - 220

58 - 2504.6 - 90078 - 120

63 - 100

169 - 59,00015,000 - 62,0006,000 - 97,000

300 - 26,000165 - 22,000251 - 64,000

3508,000 - 61,000

Non-Carcinogenic PAHs

AcenaphtheneAcenaphthylene CD]Anthracene CD]Benzo(g>h,i)perylene CD]Benzo(e)pyreneBiphenylFluorantheneFluorene CD]Naphthalene CD]PerylenePhenanthrenePyrene [D]

1.7

10 - 70

14.80.3 - 40

46.2

301 - 19.7

65

11 - 1366

53 - 130

120 - 2109.7

14 - 1848 - 14099 - 150

900 -60 -

200 -

100 -

145 -

47,00014,000

166,000

4,800

147,000

C] = Symbols in brackets refer to EPA's carcinogenic ueight-of-evidence classification.

SOURCES:IARC (1973, 1983)Blunter et al. (1977)White and Vanderslice (1980)Windsor and Kites (1979)Pucknat (1981)Eduards (1983)Butler et al. (1984)Vogt et al. (1987)Jones et al. (1989)

13

samples. The third group of samples are located within the boundaries of thesite. These are referred to as On Site samples. Those sampling locations

which comprise the different sampling groups are presented in Table 8. The

summarized chemical data for these surface soil groups is presented in Table

9. Chemicals marked with a star (*) indicate those chemicals selected as

chemicals of potential concern (see below).

2.1.2 Selection of Chemicals of Potential Concern for Surface Soils

The organic chemicals detected in On Site surface soils were compared tothose chemicals detected in blank samples. Methylene chloride and toluene

were eliminated as chemicals of potential concern because the maximum detectedconcentrations were less than ten times the maximum blank concentration as per

USEPA (1989a) guidance. A comparison of maximum detected inorganic chemicals

to detected inorganic chemicals in both the RI background sample and regional

U.S. Geological Survey (USGS) background samples (presented in Table 3) was

performed for inorganic chemicals. This approach was applied because only oneRI background surface soil sample was available. This limited amount of data

does not accurately reflect the natural variation of background concentrations

in soils. The regional data (Boerngen and Shacklette 1981) was used,

therefore, to supplement the existing RI background data. If a chemical was

determined to be greater than or equal to both the RI and regional background,

it was selected as a chemical of potential concern. Maximum concentrations of

arsenic, beryllium, barium, cadmium, calcium, chromium, iron, lead, magnesium,

manganese, mercury, nickel, potassium, selenium, vanadium and zinc were less

than at least one (and in some cases both) of the RI and regional background

concentrations and therefore were not selected as chemicals of potential

concern.

For those chemicals detected in Off Site Downgradient surface soils,methylene chloride was eliminated as a chemical of potential concern following

a comparison to blank data as described above. In the same manner as

described above, the maximum concentration detected in Off Site surface soils

was compared to the maximum background concentration in both RI and regional

USGS background samples. Arsenic, barium, beryllium, chromium, iron, lead,

14

TABLE 8

SELECTED SOIL SAMPLE GROUPINGS(SURFICtAL AND SUBSURFACE)

BackgroundOn-Site (a) Off-Site (Upgradient)

Surficial Soil

Subsurface Soil

SD-6 SD-2 SD-1SD-7 SD-3SD-8 SD-4SD-9 SD-5SD-10 SD-12SD-11SO- 13

LW-4 PZ-17B P-2APZ-111 132-34 ft] SB-15PZ-111 [36-39 ft]PZ-12 [12-15 ft]PZ-12 [30-32 ft]

(a) On-site property includes Cells 1-12 in addition to the parcel of landdefined by an extension of Cell 12 boundaries (approximately 50 N andand 450 N) to Badfish Creek.

15

TABLE 9

SUMMARY OF CHEMICALS DETECTED IN SURFACE SOILAT CITY DISPOSAL LANDFILL



On Site (b):Organics:* Acetone* bis<2-Ethylhexyl)phthalateMethylene ChlorideToluene

Inorganics:* Aluminum* AntimonyArsenicBariumBerylliumCadmiumCalciumChromium

* Cobalt* Copper* Cyanide

IronLeadMagnesiumManganeseMercuryNickelPotassiumSelenium

* SodiumVanadiumZinc

Off Site - Doungradient (c):

Organics:* Acetone* Di-n-octylphthalateMethylene Chloride

Inorganics:* Aluminum* AntimonyArsenicBariumBerylliumCadmiumCalciumChromiumCobaltCopperCyanideIronLeadMagnes i urn

* ManganeseMercuryNickelPotassiumSelenium

* Silver* SodiumVanadium

* Zinc

Z / 71 / 23 / 71 / 7

2/22 / 22 / 22 / 22 / 22/22/22 / 22 / 22 / 22 / 22 / 22 / 22 / 22 / 21 / 22 / 22/21 / 22/22 / 22/2

4 / 51 / 44 / 5

4/43/44/44/44/44/44/44/43/44/44/44/44/44/44/42/44/44/41 / 41 / 42/44/44/4

ArithmeticMean

1,40054171.2

12,000,0006,2004,700

120,000600500

4,000,00020,00012,00029,000

608,700,000

10,0004.300,000450,000

5224,000760,000

20058,00037,00047,000

t

4,10015013

8,300,0004,7001,500

130,000410460

3,400,00013,0006,10012,000

6011,000,000

12,0002,700,000930,000

4912,000630,000

140370

31,00020,00040,000

Range of Detected Range of BackgroundConcentrations Concentrations (d)

11.5 - 9,54054

11 - 81.51.2

11,600,000 • 13,400,0005,100 - 7,2002,700 - 6,700120,000

600440 - 550

3,400,000 • 4.600,00017,000 - 22,00011,000 • 13,00024,000 • 33,000

50 • 708,410,000 • 8,990,000

10,0004,100,000 - 4,490,000316,000 - 590,000

5323,000 - 25.000580.000 - 950,000

33057,000 • 58,00030,000 • 44,000

47,000

6.9 • 20,300149

10.6 • 19.5

6,040,000 - 13.400,0003,800 - 5,200960 - 2,300

81,000 - 200,000210 - 680250 • 950

620,000 • 9,300,0007,300 - 20,0005,900 - 10,0007,500 - 25,000

40 • 903,500,000 - 15,200,000

10,000 - 13,0001,100,000 - 6,330,000110,000 - 2,010,000

45 • 554,800 - 18,000

410,000 - 910,000320870

28,000 • 74,0006,900 - 28,00022,000 - 50,000

NOND

18.3ND

7,360,0003,900

NO130,000

380790

1,800,00010,0002,40014,000

703,900,000

11,000950,000147,000

ND8,700

550,000350ND

8,00034,000

NDND18

7,360,0003,900

ND130,000

380790

1,800,00010,0002,40014,000

703,900,000

11,000950,000147,000

ND8,700

550,000350NDND

8,00034,000

* = Chemical of Potent .31 ConcernNA = Not Applicable, since there was only one sample.ND = Not Detected(a) The number of samples in which the contaminant was detected divided by the total number of samples analyzed.(b) Includes surface soil samples SD-6, SD-7, SD-8, SD-9, SO-10, SO-11, and SO-13.(c) Includes surface soil samples SO-2, SD-3, SD-4, SD-5, and SD-12.(d) Background consists of surface soil sample SO-1.

magnesium, mercury, nickel, potassium, selenium, and vanadium were not

selected as chemicals of potential concern as the maximum detectedconcentration of these chemicals was less than at least one (and in some cases

both) of the maximum concentrations detected in the RI and regional backgrounddata.

As mentioned above, it is important to recognize that the USEPA Region V

approach used to select inorganic chemicals is very conservative, because thenatural variation in background concentrations is not taken into account in adirect comparison of maximum concentrations. Thus, it is likely that severalof the inorganics selected based on the criteria described earlier in thissection are, in fact, not site related. This conclusion is supported by thefact that the conservative selection criteria resulted in the selection ofsome inorganics in the downgradient off-site data set that were not evenselected in the on-site data set. As noted earlier, alternative statisticaltests will be considered in the Baseline RA for selecting chemicals ofpotential concern where less than three background samples are available.

2.2 Subsurface Soils

2.2.1 Data Summary^

Eight subsurface soil samples were collected. The same data groupings(On Site, Off Site and Background) as surface soils were used for subsurfacesoils. Those sampling locations which comprise each group are listed in Table

8. The summarized chemical data for the subsurface soil groups is presentedin Table 10.

2.2.2 Selection of Chemicals of Potential Concern for Subsurface Soil

Methylene chloride was not selected as a chemical of potential concern in

On Site subsurface soils based on a comparison to blank data. All other

organics detected in On Site subsurface soils were selected as chemicals ofpotential concern. As with surface soils, the maximum detected concentrations

in subsurface soils were compared to RI and regional USGS background data

17

TABLE 10

SUMMARY OF CHEMICALS DETECTED IN SUBSURFACE SOILAT CITY DISPOSAL LANDFILL


hemical

n Site (b):

rganics:AcetoneBenzoic acidBis(2-ethylhexyl )phthalate2-ButanoneButylbenzylphthalateDi -n-butylphthalateDi-n-octylphthalateDibenzofuranEthyl benzeneFluoreneMethylene Chloride2-MethylnaphthaleneNaphthalenePhenolTetrahydrofuranToluenem-Xyleneo&p-Xylene

norganics:* Aluminum* AntimonyArsenicBariumBeryl I tun

* Boron* Cadmium* CalciumChromiumCobaltCopperIron

* Lead* MagnesiumManganeseNickelPotassium

* SodiumVanadiumZinc


2/31 / 33/3/ 3/ 3/ 3/ 3/ 3/ 3/ 3/ 3/ 3

1 / 31 / 31 / 31 / 31 / 31 / 3

3 / 31 / 32/33/32 / 32/22/33/33/31 / 33/33 / 33 / 33 / 33/33 / 33/33/33/33/3

ArithmeticMean

2,50095

5,80013,0005,100

6623,000

31037,000

2704.4

1,700620580

3,20012,00079,00078,000

870,0006,600720

5,800110

97,000690

65,000,0003,400890

6,1004,100,000

28,00034,000,000

130,0002,500

200,000130,0009,5008,700

Range of DetectedConcentrations

13.2 - 4,99595.3

56.7 - 17,20025,60015,00066.2

70,100561

111,0004224.4

4,7301,4901,3706,44536,700236,000233,000

540,000 - 1,500,0006,700955 - 970

4,000 - 8,65036 - 195

69,500 - 125,000405 - 1.450

37,650,000 - 102,650,0001,200 - 4,900

2.2503,800 - 9,650

2,350,000 - 7,175,0001,400 - 80,000

19,150,000 - 53,450.000104,500 - 176,5001,200 - 4,200

125,000 - 310,00080,000 - 170,0004,100 - 16,0005,100 - 12,700

Range of BackgroundConcentrations (d)

12.5 - 17.2NO

168.5NONDNONDNDNDND

8 - 9.5NDNDNDND1.7NDND

910,000 - 970,000ND

915 - 2,4004,300 - 19,00076.3 - 10010,750

7356,345,000 - 48,800,000

4,000 - 5,9001,227.5 - 2,6008,650 - 9,400

2,500,000 - 4,550,0001,120 - 3,400

1,910,000 - 26,700.000189,000 - 426,5004,300 - 6,650

362,000 * 495,00067,000 - 110,0005,650 - 6,50021,000 - 33,500

18

TABLE 10 (Continued)

SUMMARY OF CHEMICALS DETECTED IN SUBSURFACE SOILAT CITY DISPOSAL LANDFILL


ChemicalFrequency ofDetection (a)

ArithmeticMean


Range of BackgroundConcentrations (d)

Off Site (c):

Organics:Methylene Chloride 1 / 1 NA 3.3 8 - 9.5

Inorganics:* AluminumArsenicBariumBeryllium

* BoronCalciumChromiumCobalt

* Copper* Cyanide

IronLeadMagnesiumManganeseNickelPotassiumSodiumVanadiumZinc

/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1

I / 1/ 1/ 1

NANANANANANANANANANANANANANANANANANANA

2,345,0001,34512,000

11517,000

31,150,0004,7503,30013,5006,275

5,190,0001,175

15,850,000151,0003,300

795,00053,00010,90011,000

910,000 - 970,000915 - 2,400

4,300 - 19.00076.3 - TOO10,750

6,345,000 - 48,800,0004,000 - 5,900

1,227.5 - 2,6008,650 - 9,400

3002,500,000 - 4,450,000

1,120 - 3,4001,910,000 - 26,700,000189,000 - 426,5004,300 - 6,650

362.000 - 495,00067,000 - 1-10,0005,650 - 6,50021,000 - 33,500

* * Chemical of Potential ConcernNA = Not Applicable, since there was only one sample.ND - Not Detected(a) The number of samples in which the contaminant was detected divided by the total number of samples analyzed.(b) Includes subsurface soil samples LW-4, PZ-11I (32-34 ft), PZ-11I (36-39 ft), PZ-12 (12-15 ft), and PZ-12

(30-32 ft.).(c) Includes subsurface soil sample PZ-17B.(d) Background consists of subsurface sofl samples P-2A and SB-15.

19

(Boerngen and Shacklette 1981) due to an insufficient number of RI background

samples available. Of the inorganic chemicals detected in the On Site group,

the maximum detected concentrations of arsenic, barium, beryllium, chrc. ,um,cobalt, copper, iron, manganese, nickel, potassium, vanadium, and zinc weredetermined to be less than at least one of the maximum detected concentrationsin the RI and regional background samples and therefore were not selected aschemicals of potential concern.

In the Off Site subsurface soil group, methylene chloride was the onlyorganic chemical detected and it was not selected based on a comparison toblank data. Of the inorganic chemicals, arsenic, barium, beryllium, calcium,chromium, cobalt, iron, lead, magnesium, manganese, nickel, potassium, sodium,vanadium, and zinc were not selected as chemicals of potential concern. The

maximum concentrations of these chemicals were determined to be less than atleast one of the maximum RI and regional background concentrations. Theuncertainties mentioned above in Section 2.1.2 regarding selection ofinorganics in surface soil also apply to subsurface soil.

2.3 Ground Water

2.3.1 Data Summary

Groundwater at the City Disposal site was first grouped according toaquifer. Two aquifer groupings were chosen. The shallow and intermediategroundwater (in glacial materials) wells which are both influenced by theglacial materials were grouped together to form the shallow and intermediate

(S&I) aquifer. The bedrock wells form the bedrock aquifer group.

For the S&I aquifer wells, those wells which are located within the

boundaries of the site were included in the On Site group. Additionally,those wells which are located in close vicinity to the site boundaries andtherefore could be potentially influenced by site activities were also

included in the On Site group. Site studies indicate that groundwater in thewater table in the vicinity of the site flows in essentially two dominantdirections: (1) toward the northeast under the eastern portion of the

20

landfill; and (2) toward the north under the western portion of the landfill.Due to this variability in groundwater flow, off-site downgradient wells weredivided into two groups. The wells located off site and northeast of thelandfill were included in the Northeast Downgradient group and those wellslocated off site and north of the landfill were included in the North.Downgradient group. The East of Badfish Creek group consists of only onewell. The Background group contains samples which are upgradient of the site.As with the soil grouping above, this group of data contains samplinglocations which are hydrologically located in such a way that contaminant

migration from the site to these locations is not considered to occur. Thegroupings for the S&I aquifer wells are summarized in Table 11. Thesummarized chemical data for the S&I groundwater group is presented in Table12.

The direction of groundwater movement in the bedrock aquifer is generallytoward the north. In the same manner as the S&I aquifer group above, thosewells which are located within the boundaries of the site were included in theOn Site group. The Off Site Downgradient group contains those wells whichcould potentially be impacted by migration from the site. The Backgroundgroup contains those samples which are not considered to be affected bychemical migration from the site. The groupings for the Bedrock aquifer wellsare listed in Table 13. The summarized chemical data for the Bedrockgroundwater groups is presented in Table 14.

Four residential wells in the vicinity of the City Disposal Landfill weresampled and analyzed for chemical constituents during the RI. Because these

wells are relatively distant from the site and from each other, each well isevaluated separately. The four residential wells are: well(located approximately 55 m ENE of the SE corner of the landfilled area),

well (located approximately 250 m S of the SW corner of thelandfilled area), well (located approximately 500 m WSW of the SW cornerof the landfilled area), and well (located approximately 452 m ESE

of the SE corner of the landfilled area. The private wells are the main watersource at these residences. The summarized chemical data for theseresidential wells is presented in Table 15.

21

TABLE 11

SELECTED GROUNDWATER WELL GROUPINGS(SHALLOW AND INTERMEDIATE WELLS)

Off Site (b)

NorthOn Site (a) Downgradient

PZ-5 PZ-16P2-6 P2-17PZ-9 PZ-Z1SPZ-11DPZ-11IPZ-11SPZ-13PZ-18-1B-1C-2B-2C-46-4C-5A-8A-10A

B-6RRB-7RRB-9ARB-9RRB-12RRB-16RRB-18RRB-19RR

Northeast Background East ofDowngradient (Upgradient) Badfish Creek

PZ-8 PZ-10 PZ-22SP-3B PZ-14 PZ-22DP-3C PZ-15P-6A P-7A

P-9AB-14RRB-17RR

(a) The site includes Cells 1-12 in addition to the parcel of land defined by an extension of Cell 12boundaries (approximately 50 N and 450 N) to Badfish Creek.

(b) Off-site doungradient samples defined by the general direction of the grounduater plume due to theexistence of two plumes in the water table.

22

TABLE 12

SUMMARY OF CHEMICALS DETECTED IN GROUNDUATERAT CITY DISPOSAL LANDFILL

SHALLOW AND INTERMEDIATE WELLS(Concentrations reported in ug/L)

Chemical

On Site (b)

Organ ics:AcetoneBenzeneBenzoic acid2-ButanoneCarbon TetrachlorideCh loroethane1,1-Dich loroethane1 , 2-0 i ch I oroethanetrans-1,2-Dichloroethene1 , 2-0 i chl oropropaneDiethylphthalateEthylbenzene2-HexanoneItophorone4-Methy I -2-pentanoneMethylene Chloride2-Methy I phenol4-MethylphenolPhenolPhenols (total)1 , 1 ,2, 2-Tetrach loroethaneTet rach I oroet heneTetrahydrofuranToluene1,1,1-TrichloroethaneTrichloroetheneVinyl AcetateVinyl Chloridem-Xyleneotp-Xylenes

Inorganics:AluminumAnmonia

* Arsenic* BariumBoron

* Cadmium* CalciumChloride

» CobaltCopperCyanideFluor ide

* Iron* Lead* Magnesium* Manganese* Nickel

NitratePotassium

* Selenium* Silver* SodiumSulfateZinc


22 / 2512 / 252/129/251 / 258/2510 / 251 / 2514 / 256/251 / 129/252/251 / 1210 / 2522 / 251 / 124/122/121 / 171 / 2510 / 2514 / 2512 / 255 / 2513 / 251 / 254 / 258/2511 / 25

1 / 65/175 / 66 / 617 / 171 / 6

25 / 2525 / 253 / 65 / 616 / 1625 / 2519 / 251 / 625 / 2523 / 255 / 66/1720 / 251 / 61 / 6

25 / 2525 / 256 / 6

ArithmeticMean

5.1003.240

27,000247.736651902.44.1915.11.9200841.6148.2301.220

14,0001,4004.5473.9120140150

1110015170710.2

130,00037,000

6.53.81.2200

7,6000.4

67,00043015200

2,5000.32.7

16,00017,000

24


3.1 - 102,6501.6 - 7.810.6 - 202125.6 - 622,500

109.33.2 - 29.11.8 - 179.5871.72.2 - 1,1101.7 - 2.6

4.12 - 766

6.2 - 6.81.9

3.2 - 3,4001.8 - 767

1.62.1 - 95.61.5 - 42.4

801.2

1.7 • 11062.2 - 199.5002.9 - 25,9002.2 - 16.91.7 - 277

3.93.3 - 1,2502.3 - 1,5002.1 - 1,560

37100 - 1,5002.8 - 6348 - 6705.7 - 280

0.544,000 - 280,0002.600 - 139,9007.3 - 172 - 10

0.3 - 3.1100 - 30029 - 52,900

15,600 - 126,0003.3 - 2,1803.4 - 34200 - 1,200800 - 12,000

0.66.3

2,700 - 50,2004,300 - 34,8007.8 - 45

Range of BackgroundConcentrations (f)

5.7 - 13.4NONONONONONDNDNONDNDNDNDNDND

1.7 - 5NDNDNDNDNDNDNDNDMD1.4NONONONO

ND2008.2

71 - 11028 - 89

ND68,000 - 93,0004,400 - 35,900

NDND

1.3 - 1.6100 - 5009.3 - 440

ND33,000 - 55.200

17 - 4564.3300

1,500 - 4,100NDND

3,000 - 9,60012,000 - 50,000

19

TABLE 12 (Continued)SUHHARY OF CHEMICALS DETECTED IN GROUNOUATER

AT CITY DISPOSAL LANDFILLSHALLOW AND INTERMEDIATE WELLS

(Concentrations reported in ug/L)


Offsite - North Downgradient (c)

Organics:Acetone

* 1,1-DichloroethaneMethylene Chloride

* TetrachloroetheneToluene

* 1,1,1-Trichloroethane* Trichloroethene

Inorganics:CalciumChlorideFluorideIronMagnesiumManganesePotassiumSodiumSulfate

Offsite - Northeast Downgradient

Organics:Acetone

* 4-Methyl -2-pentanoneMethylene Chloride

* 1,1,2,2-Tetrachloroethane

Inorganics:BariumBoronCalciumChlorideCyanideFluorideIronMagnesiumManganese

* NitratePotassiumSodiumSulfateZinc

2 /1 /1 /2 /1 /1 /2 /

3 /3 /3 /1 /3 /3 /3 /3 /3 /

(d)

4 /2 /4 /1 /

1 /3 /4 /4 /3 /3 /4 /4 /3 /3 /3 /4 /4 /1 /

3333333

333333333

4444

13443444434441

ArithmeticMean

261.8

13.60.90.94

70,0009,200200140

40,000200

5,30043,00049,000

6.32.72.71.3

NA28

82,0009,1000.8200150

41,00082

8,3002,3006,60021,000

NA


18.9 - 54.11.8

13.5 - 4.8

0.90.9

2.8 - 6.8

54,000 - 81,0003,200 - 15,100100 - 400

41034,000 - 49,000

8.9 - 3201,300 - 8,7003,000 - 120,00022,600 - 87,000

4.7 - 7.71.9 - 3.41.9 - 3.2

1.3

2026.5 - 30

60,850 - 94,0006,800 - 11,8000.7 - 0.9200 - 40022 - 440

34,050 - 51,0005.5 - 190400 - 17,700

1,500 - 5,8005,400 - 9,65013,100 - 28,000

17


5.7 - 13.4ND

1.7 - 5NONDND1.4

68,000 - 93,0004.400 - 35,900100 • 50093 - 440

33,000 - 55,20017 - 450

1,500 - 4,1003,000 - 9,60012,000 - 50,000

5.7 - 13.4ND

1.7 - 5ND

71 - 11028 - 89

68,000 - 93,0004,400 - 35,900

1.3 - 1.6100 - 50093 - 440

33.000 - 55,20017 - 450300

1,500 - 4,1003,000 - 9,60012,000 - 50,000

19

24



SHALLOW AND INTERMEDIATE WELLS(Concentrations reported in ug/L)


ArithmeticMean



East of Badfish Creek (e)

Organ ics:Acetone

* trans-1,2-Dichloroethene* TetrahydrofuranToluene

* TrichloroetheneInorganics:* Calcium* Chloride

FluorideIronMagnesium

* Manganese* Potassium* SodiumSulfate

1 /2 /1 /1 /1 /

2 /2 /2 /1 /2 /2 /2 /2 /2 /

22222

222222222

1937581.82.5

97,000190,000

400130

49,0008405200

10000038

32.421.5 - 51.6

1101.82.6

83.000 - 110,000178,800 - 208,700

400250

44,000 - 54,000710 - 970

4,900 - 5,50098,000 - 110,00032.2 - 44.5

5.7 - 13.4NONONO1.4

68,000 - 93,0004,400 - 35,900100 - 50093 - 440

33,000 - 55,20017 - 450

1,500 - 4,1003,000 - 9,600• 12-50

* = Chemical of Potential Concern

NA = Not Applicable, since there was only one sample.ND * Not Detected

(a) The number of samples in which the contaminant was detected divided by the total number of samplesanalyzed.

(b) Includes samples PZ-5, PZ-6, PZ-9, PZ-11D, PZ-111, PZ-11S, PZ-13, PZ-18, P-1B, P-1C, P-2B, P-2C, P-4B,P-4C, P-5A, P-8A, P-10A, B-6RR, B-7RR, B-9AR, B-9RR, B-12RR, B-16RR, B-18RR, B-19RR.

(c) Includes samples PZ-16, PZ-17, and PZ-21S.(d) Includes samples PZ-8, P-3B, P-3C, and P-6A.(e) Includes samples P2-22S and PZ-22D.(f) Background consists of samples PZ-10, PZ-14, PZ-15, P-7A, P-9A, B-14RR, and B-17RR.

25

TABLE 13

SELECTED GROUNDUATER WELL GROUPINGS(BEDROCK WELLS)

BackgroundOn Site (a) Off Site (Upgradient)

P-1A P-3A P-2AP-4A P2-21DB

(a) The site includes Cells 1-12 in addition to the parcel of landdefined by an extension of Cell 12 boundaries (approximately50 N and 450 N) to Badfish Creek.

26

TABLE 14


BEDROCK WELLS(Concentrations reported in ug/L)

Frequency of Arithmetic Range of Detected Range of BackgroundChemical Detection (a) Mean Concentrations Concentrations (e)

On Site <b>:Organics:

Acetone 1/2 4.1 4.1 7.3* 1,1-Dichloroethane 1/2 0.7 0.7 ND* trans-1,2-Dichloroethene 1/2 13 24.2 NDMethylene Chloride 2/2 2.8 2 - 3.6 8.2

* Trichloroethene 2/2 6.6 2.3 - 10.9 ND

Inorganics:Barium 1/1 NA 57 110Boron 2/2 23 8.3-37 40

* Cadmium 1/1 NA 0.9 NDCalcium 2/2 73,000 64,500-81,550 79,850Chloride 2/2 3,900 3,100 - 4,800 45,500Copper 1/1 NA 2 NDCyanide 2/2 0.3 0.1 - 0.5 0.6Fluoride 2/2 100 100 - 200 100Iron 2/2 30 24.8 - 34.5 NDMagnesium 2/2 37,000 31,000 - 43,800 40,600Manganese 2/2 5 2-8 1.5Nitrate 1/2 400 700 8,700Potassium 1/2 520 630 1,800Sodium 2/2 3,200 3000 - 3,350 19,500Sulfate 2/2 27,000 23,700 - 30,300 25,700Zinc 2/1 NA 13 16

Off Site - Downgradient (c):

Organics:Acetone

* Chlorobenzene* 1,1-Dichloroethane* trans-1,2-Dichloroethene* 2-Hexanone* 4-Methy I -2- pentanoneMethylene Chloride

* 1, 1,2, 2- Tetrach I oroethane* Tetrachloroethene* TetrahydrofuranToluene

* 1 ,1,1-Trichloroethane* Trichloroethene* o&p-XylenesInorganics:

BariumBoron

* CalciumChlorideCopperCyanideFluorideIronMagnesiumManganesePotassiumSodiumSulfateZinc

2/21 / 21 / 21 / 21 / 21 / 21 / 21 / 21 / 22 / 21 / 21 / 21 / 21 / 2

1 / 11 / 12/22 / 21 / 11 / 12 / 22/22 / 22 / 22/22 / 22 / 21 / 1

8.61

4.4434.65.13

2.65.2220.92.8381.1

NANA

94,0005,800

NANA100670

46,00077

1,9003,80027,000

NA

4 - 13.21

6.384.14.65.23.52.68

12.3 - 31.80.93.274.21.1

7325

68,125 - 120,0002,600 - 9,100

3.20.7100

43 - 1,30033,950 - 59,000

68 - 851,600 - 2,2003,300 - 4,20025,000 - 29,400

16

7.3NDNDNDNDND8.2NDNDND0.9NDNDND

11040

79,85045,500

ND0.6100ND

40,6001.5

1,80019,50025,700

16

* = Chemical of Potential ConcernNA = Not Applicable, since there was only one sample.ND = Not Detected

(a) The number of samples in which the contaminant was detected divided by the total number of samplesanalyzed.

(b) Includes bedrock well samples P-1A and P-4A.(c) Includes bedrock well samples P-3A and PZ-21DB.(d) Background consists of bedrock well sample P-2A.

TABLE 15


RESIDENTIAL WELLS(Concentrations reported in ug/L)

Frequency of ArithmeticChemical Detection (a) Mean

B latter-man Well (b)

Organics:Toluene 1/1 NA

Inorganics:Boron 1/1 NACalcium /Chloride /Cyanide /Fluoride /Iron /Magnesium /Nitrate /Potassium 1 /

* Sodium 1 /Sulfate 1 /

NANANANANANANANANANA


2.8

14.592,00029,200

1.510058

44,0006,4001900

12,00038,200

Well (c)

Organics:Methylene ChlorideToluene

Inorganics:BoronCalciumChlorideCyanideFluorideIronMagnesium

* ManganesePotassiumSodiumSulfate

/ 1/ 1/ 1

NANA

NANANANANANANANANANANA

4.73.1

9.748,0007,300

1.5100

3,40022,000

3201,7002,00025,600

Well (d)

Inorganics:CalciumChlorideCyanideFluorideIronMagnesiumManganeseNitratePotassiumSodiumSulfate

1 / !1 / 11 / 11 / 11 / 11 / 11 / 11 / 1


84,00026,400

1.2100

2,10040,000

110300

1,4006,700

36,800

28


SUMMARY OF CHEMICALS DETECTED IN GROUNOWATERAT CITY DISPOSAL LANDFILL

RESIDENTIAL WELLS(Concentrations reported in ug/L)


ArithmeticMean

Range of DetectedOn-Site Concentrations

Well (d)

Organ ics:AcetoneMethylene Chloride

Inorganics:BoronCalciumChlorideCyanideFluor ideIronMagnesiumNitratePotassiumSodiumSulfate

/ 1/ 1

/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1

NANA


8.88.9

2078,00013,700

0.810027

38,0002,0001,2004,10027,100

* = Chemical of Potential ConcernNA = Not Applicable, since there was only one sample.(a) The number of samples in which the contaminant was detected divided by the

total number of samples analyzed.(b) Located approximately 500 m ENE of the SE corner of the landfilled area.(c) Located approximately 250 m S of the SW corner of the landfilled area.(d) Located approximately 500 m WSU of the SW corner of the landfilled area.(e) Located approximately 425 m ESE of the SE corner of the landfilled area.

29

2.3.2 Selection of Chemicals of Potential Concern for Groundwater

2.3.2.1 Shallow and Intermediate (S&I) Groundwater

All organic chemicals detected in the On Site group for the S&Igroundwater were selected as chemicals of potential concern. A comparison of

the organic data to blank concentrations showed that those chemicalsconsidered to be common laboratory contaminants were detected in on sitegroundwater at levels greater than ten times the blank concentrations.

Ammonia, boron, chloride, cyanide, fluoride, nitrate, potassium, and sulfatewere determined to be less than background levels using the Behrens-Fisher

Students' t-test and were not selected as chemicals of potential concern. As

discussed previously in Section 2.0, the statistical theory and availableguidance from the USEPA concerning this topic (e.g., USEPA 1989a,b, 1988a,b,c)will be reviewed to verify whether the student's t-test is the mostappropriate statistical test. Therefore the selected chemicals may changeslightly in the Baseline RA if another test is determined to be moreappropriate and is applied. Justification will be provided in the Baseline RAto support the use of any alternative statistical test. In accordance withUSEPA (1989a) guidance, aluminum, copper, and zinc were also not selected aschemicals of potential concern as the detected maximum concentrations were

within five times the maximum blank concentrations.

Acetone, methylene chloride, and toluene were not selected as chemicals

of potential concern in the North Downgradient S&I group based on a comparison

to blank data. All other detected organics were selected. All inorganics

were determined using the Behrens-Fisher Students' t-test to be less than

background and therefore no inorganic chemicals were selected as chemicals of

potential concern.

Based on a comparison to blank data, acetone and methylene chloride were

not selected as chemicals of potential concern in the Northeast DowngradientS&I group. For inorganics, only nitrate was selected as a chemical ofpotential concern. Because an insufficient number of samples were available

30

to perform the student's t-test for barium and zinc, these chemicals werecompared to background using the method recommended by USEPA Region V (asdescribed in Section 2.0). Barium and zinc were determined to be less than atleast one of the RI and regional background concentrations based on acomparison of the maximum on-site concentration to these maximum backgroundconcentrations. All other inorganics were found to be within backgroundlevels using the Behrens-Fisher Students' t-test.

For the East of Badfish Creek S&I group, acetone and toluene were notselected as chemicals of potential concern based on a comparison to blankdata. Because only two samples were taken, the student's t-test could not beapplied to the inorganics. Therefore, these inorganic chemicals were alsocompared to background using the method recommended by USEPA Region V (seeSection 2.0). The maximum detected concentrations of fluoride, iron,magnesium, and sulfate were determined to be less than at least one of themaximum detected RI and regional background concentrations (and in some casesboth) and were not selected as chemicals of potential concern. All otherinorganic chemicals were selected.

2.3.2.2 Groundwater in Bedrock

For the On Site Bedrock groundwater group, acetone and methylene chloride\^ were determined to be within ten times the maximum blank concentration and

were therefore not selected as chemicals of potential concern. For

inorganics, the maximum detected concentration in the bedrock wells wascompared to the maximum detected concentrations in both the RI and regionalbackground data (see Table 2). This approach was applied because only two RIbackground samples were available for bedrock wells. This limited amount ofdata does not accurately characterize the natural variation of backgroundconcentrations in groundwater. Regional data from Dane County wells (Cline1965) was therefore used to supplement the existing RI data. If a chemical

detected in groundwater in bedrock was determined to be greater than or equalto both the RI and regional background data, it was selected as a chemical ofpotential concern. For the inorganics, the maximum detected concentrations ofbarium, boron, calcium, chloride, cyanide, fluoride, iron, magnesium,

31

manganese, nitrate, potassium, sodium, sulfate, and zinc were determined to be

less than at least one (and in many cases both) of the maximum detected RI and

regional background concentrations and were not selected as chemicals of

potential concern. Additionally, copper was eliminated as a chemical of

potential concern because its maximum detected concentration was within five

times the maximum blank concentration.

For the Off Site Downgradient Bedrock groundwater group, acetone,

methylene chloride, and toluene were eliminated as chemicals of potentialconcern based on a comparison to blank data. For the inorganics, the maximumdetected concentrations of barium, boron, chloride, fluoride, iron, magnesium,manganese, potassium, sodium, and sulfate were determined to be less than atleast one of the maximum RI and regional background concentrations and werenot selected as chemicals of potential concern. Copper, cyanide, and zincwere also eliminated as chemicals of potential concern because the maximum

detected concentrations of these chemicals were within five times the maximumdetected concentration in blank samples.

2.3.2.3 Residential Wells

In the same manner as the bedrock well data, the residential well datawas compared to both RI and regional (Cline 1965) background data due to thesmall number of RI background samples available. Again, a chemical wasselected as a chemical of potential concern if the maximum detectedconcentration in the residential well was equal to or exceeded both themaximum detected concentrations in the RI and regional background. The

well, well and well are reportedly tapping the

bedrock aquifer. Therefore RI background data for the bedrock aquifer wasused for these wells. The well is reportedly tapping the S&Iaquifer, therefore the S&I aquifer RI background data was used for this well.

For the residential well, toluene was the only organic

chemical detected and it was not selected as a chemical of potential concernbased on a comparison to blank data. For inorganics, boron, calcium,

32

chloride, fluoride, iron, magnesium, nitrate, potassium, and sulfate were notselected as chemicals of potential concern because the maximum detectedconcentrations of these chemicals were determined to be less than at least oneof the maximum RI and regional background concentrations. Cyanide was alsonot selected since the maximum detected concentration in the well was withinfive times the maximum concentration in blank data.

For the well, methylene chloride and toluene were the only twoorganic chemicals detected and they were not selected as chemicals ofpotential concern based on a comparison to blank data. For inorganics, boron,calcium, chloride, cyanide, fluoride, iron, magnesium, potassium, sodium, andsulfate were not selected as chemicals of potential concern. These chemicalswere determined to be less than background based on the comparison to Rlbackground and regional background as described above.

For the well, no organic chemicals were detected. Of the inorganicchemicals, calcium, chloride, fluoride, iron, magnesium, manganese, nitrate,potassium, sodium, and sulfate were determined to be less than RI and regionalbackground using the methodology described above and were not selected aschemicals of potential concern. In addition, cyanide was not selected as achemical of potential concern as it was within five times the concentration

***—/ detected in blank data.

Acetone and methylene chloride were the only organic chemicals detectedin the well. Neither of these were selected as chemicals ofpotential concern based on a comparison to blank data. For the inorganicchemicals, no chemicals were selected as chemicals of potential concern.Boron, calcium, chloride, fluoride, iron, magnesium, nitrate, potassium,sodium, and sulfate were determined to be less than either RI or regionalbackground (or both). The maximum concentration of cyanide detected in the

well was determined to be within five times the maximumconcentration detected in the blanks. Therefore, this chemical was notselected as a chemical of potential concern.

33

2.4 Summary of Chemicals of Potential Concern

Table 16 summarizes the chemicals of potential concern selected for

groundwater at the City Disposal Landfill. Table 17 summarizes the chemicalsof potential concern selected for soils at the City Disposal Landfill. Thesechemicals will be quantitatively evaluated in the Baseline RA.

3.0 TOXICITY ASSESSMENT

The general methodology for the classification of health effects will bedescribed in this section to provide the analytical framework for thecharacterization of human health impacts. Brief summaries of the toxicity ofthose chemicals that will be evaluated quantitatively in this assessment will

be included. In addition, the quantitative dose-response values that will beused in the Baseline RA will be provided (cancer slope factors and referencedoses). For carcinogens, cancer slope factors (or unit risks for theinhalation pathway) and the chemicals' weight-of-evidence classifications forhuman carcinogenicity (or reference concentrations for the inhalation pathway)will be provided and discussed. For noncarcinogens, reference doses (RfDs)and the uncertainty factors used in deriving them will be provided. Theprimary source of the dose-response values will be USEPA's Integrated RiskInformation System (IRIS) and Health Effects Assessment Summary Tables

(HEASTs).

4.0 HUMAN EXPOSURE ASSESSMENT

In the human exposure assessment portion of the Baseline RA, the most

important pathways through which individuals may be exposed to chemicals

originating from the City Disposal Landfill will be evaluated. In this

section, the potential magnitude, frequency, and duration of chemical

exposures via the identified exposure pathways will be estimated. Two overall

exposure conditions will be evaluated. The Current Site and Surrounding LandUse Condition will evaluate potential risks associated with the City DisposalLandfill as it exists today, and the Future Land Use Condition will evaluate

34

TABLE 16

SUMMARY OF CHEMICALS OF POTENTIALCONCERN IN GROUNDWATER FOR THE CITY DISPOSAL LANDFILL

DUNN, WISCONSIN

(ORGANICS)

BEDROCK AQUIFERS & I AQUIFER GftOUNDUATER GROUNDWATER RESIDENTIAL WELL GROUNDWATER

CHEMICAL OFF SITE OFF SITE E. BADFISH ON SITE OFF SITE SW (a) IH (b) BL <c> LA (d)ON SITE N-OUNGRD NE-DUNGRD CREEK

Acetone x b b bBenzene xBenzoic acid xBis(2-Ethylhexyl)phthalate2-Butanone x - - -Butylbenzylphthalate . . . .Carbon Tetrachloride xChlorobenzene . . . . . xChloroethane x • -1.1-DiChloroethane x x x x1.2-Dichloroethane x - -trans-1,2-Dichloroethene x - - x x x1,2-Dichloropropane x • -Diethylphthalate x - . - .Di-n-butylphthalate . . . . . .Di-n-octylphthalate . . . . . .Dibenzofuran . . . . . .Ethylbenzene x - -Flourene . . . . . .2-Hexanone x - xIsophorone x • -4-Methyl-2-pentanone x - x - xMethylene Chloride x b b b b2-Methylnapthalene . . . . . .2-Methylphenol x - -4-Methylphenol x -Napthalene . . . . . .Phenol x - - - - -Phenols (total) x • -1,1,2,2-Tetrachloroethane x - x xTetrachloroethene x x xTetrahydrofuran x - - x - xToluene x b - b - b1,1,1-Trichloroethane x x - - - xTriChloroethane . . . . . .Trichloroethene x x - x x xVinyl Acetate x - - - -Vinyl Chloride x - -ra-Xylene x - -o&p-Xylenes x - - - - x

35


SUMMARY OF CHEMICALS OF POTENTIALCONCERN IN GROUNDUATER FOR THE CITY DISPOSAL LANDFILL

DUNN, WISCONSIN

(INORGANICS)

CHEMICAL

S & I AQUIFER GROUNDWATERBEDROCK AQUIFER

GROUNDWATER

ON SITEOFF SITE OFF SITE E. BAOFISHN-DWNGRD NE-DWNGRD CREEK

ON SITE OFF SITE

RESIDENTIAL WELL GROUNDWATER

SW (a) IH (b) BL (c) LA (d)

AluminumAnt i monyAmmoniaArsenicBariumBerylliumBoronCadmiumCalciumChlorideChromiumCobaltCopperCyanideFlourideIronLeadMagnes i urnManganeseMercuryNickelNitratePotassiumSeleniumSi IverSodiumSulfateVanadiumZinc

b

oXX

0XX0-XbooXXXX-X0oXXX0-b

-

-o0----oo-0o---o--oo-~

o

0-o0---oo0•o0--Xo--0o-o

-

-XX-•--00-oX---X--Xo-

"

0

oXo0--b0bo-ob--o0--ob-0

0

0-X0--bbbo-o0 .---o--ob-b

o-oo---bbo-o•--oo--0b-"

o-oo---oo0-0X---o--o0•"

0-00---bb0-0---oo--X0-

"

'. \m00---bbo-oo--00--00-"

(a) Swinehact private well.(b) private well.(c) private well.(d) private well.

x = Selected as a chemical of potential concern,o = Not selected; within background levels,b = Not selected; blank contamination.- = Not detected.

36

TABLE 17

SUMMARY OF CHEMICALS OF POTENTIALCONCERN IN SOILS FOR THE CITY DISPOSAL LANDFILL

OUNN, WISCONSIN

(ORGAN ICS)

CHEMICAL

SURFACE SOIL

ON OFF

SUBSURFACE SOIL

ON OFF

AcetoneBenzeneBenzoic acidBis(2-Ethylhexyl)phthalate2-ButanoneButylbenzylphthalateCarbon TetrachlorideChlorobenzeneChloroethane1.1-Dichloroethane1.2-Oichloroethanet rans-1,2-D i chIoroethene1,2-DichloropropaneDiethylphthalateDi-n-butylphthalateDj-n-octylphthalateDibenzofuranEthylbenzeneFlourene2-HexanoneIsophorone4-Methyl-2-pentanoneMethylene Chloride2-Methylnapthalene2-Methylphenol4-MethylphenolNapthalenePhenolPhenols (total)1,1,2,2-TetrachloroethaneTet rachIoroetheneTetrahydrofuranToluene1,1,1-TrichloroethaneTrichloroethaneTrichloroetheneVinyl AcetateVinyl Chloridem-Xyleneo&p-Xylenes

37


SUMMARY OF CHEMICALS OF POTENTIALCONCERN IN SOILS FOR THE CITY DISPOSAL LANDFILL

DUNN, WISCONSIN

(INORGANICS)

CHEMICAL

AluminumAntimonyAmmoniaArsenicBariumBerylliumBoronCadmiumCalciumChlorideChromiumCobaltCopperCyanideFlourideIronLeadMagnesiumManganeseMercuryNickelNitratePotassiumSeleniumSilverSodiumSutfateVanadiumZinc

SURFACE

ON

XX-00o-oo-oXXX-oo00o0-00-X-00

SOIL

OFF

XX-000-XX-oXXX-o00X0o•00XX-0X

SUBSURFACE

ON

XX-oo0XXX-00o--0XXo-0-o--X-oo

SOIL

OFF

X

-o0oX-0-o0XX•o00o-0-o--o-o0

x = Selected as a chemical of potential concern,o = Not selected; within background levels,b = Not selected; blank contamination.- = Not detected.

38

potential risks under future use conditions assuming no remedial action istaken (i.e., the no-action alternative). As will be described later (Section4.4), for each pathway only a reasonable maximum exposure (RME) scenario willbe evaluated in response to USEPA Region V requirements.3

4.1 Site Characterization

This section will identify the potentially exposed populations and theirrelative locations with respect to the City Disposal Landfill. Factors suchas population activity patterns in the area, source characteristics, androutes of transport are considered when identifying potentially exposedpopulations. Based on our current understanding of the site, potential humanreceptors include trespassers on the site, site workers, residents near thefacility, and residents who depend on water from nearby wells.

4.2 Identification of Exposure Pathways

An exposure pathway describes the course a chemical takes from the sourceto the receptor. An exposure pathway generally consists of four components:1) a source and mechanism of release, 2) an environmental transport medium, 3)a point of potential exposure with the contaminated medium; and 4) a route ofexposure (e.g., inhalation) at the exposure point. When all these elementsare present, a pathway is considered "complete". Tables 18 and 19 (currentand future, respectively) summarize the exposure pathway analysis for the CityDisposal Landfill. The tables indicate the exposure medium, release

mechanism, exposure point, potential receptor and route of exposure. The

tables also indicate whether each pathway is potentially complete, and thosepathways that will be quantitatively evaluated in the Baseline RA.

A variety of exposure pathways will be evaluated in the baseline riskassessment. These pathways involve the inhalation of airborne chemicals,ingestion and dermal absorption of chemicals in soil, ingestion and inhalation

3Personal communication with P. Van Leeuwen. USEPA Region V. June 4,1991.

39

TABLE 18

POTENTIAL EXPOSURE PATHWAYS FOR THE CUT DISPOSAL LAWFULCURRENT SITE AMD SURROUNDING LAND USE

Exposure Mediua

Air

Air

Air

Air

0 Air

Soil

Soil

Creek sediaent

Mechanisas of Release

Volatilization froa thelandfill

Volatilization froa thelandfill

Volatilization froasurface water

Fugitive dust froa surface soils

Fugitive dust froa surface soils

Direct contact with surface soils

Direct contact with subsurfacesoils

Landfill surface runofffroa the site

Exposure Point

On site

Off site

Off site, Badfish Creek

On si te

Off site

On si te

On site

Off site, Badfish Creek

Potential Receptor

Workers, trespassers

Residents

Residents


Residents



Residents

Route of Exposure

Inhalation

Inhalation

Inhalation

Inhalation

Inhalation

Incidental ingestion.deraal absorptionIncidental ingestion.deraal absorption

Incidental ingestion.deraal absorption

PathwayCoaplete?

res

res

res

No

No

res

No

res

Quantitatively Evaluated? Basis.

res. On site soil data and volatilization and airdispersion Modeling.

res. On site soil data and volatilization and airdispersion modeling.

No. VOCs not expected to aigrate to Badfish Creekvia surface runoff or groundwater recharge.

No. Surface of landfill is well vegetated.

No. Surface of landfill is well vegetated.

res. On site surface soil data.

No. Subsurface soils not likely to be contactedby trespassers/workers on site.

No. VOCs not expected to aigrate to Badfish Creeksediaents via surface runoff or groundwater

Msh Landfill surface runoff/groundwater recharge toGrass Lake

Off site, Grass Lake Residents Ingestion

recharge.

No. Site investigations have documented thatgroundwater flowing froa. City Disposal site doesnot discharge into Grass Lake, nor does runofffroa the site affect the lake.

fish Landfill surface soil runoff/groundwater recharge toBadfish Creek

off site, Badfish Creek Residents Ingestion No. S i t e investigations have shown that groundwaterdoes not recharge into Badfish Creek, also there isa low potential for surface runoff to the creekas the landfill is well vegetated. Badfish Creekis also the aajor discharge for treated effluent froathe Madison sewage treataenr plant. Creek waters aresoaetiaes maloderous which likely deters activities inthe creek. There is no known fishing in the v i c i n i t yof the site.

r r


POTENTIAL EXPOSURE PATHWAYS FOR IKE CITY DISPOSAL LANDFILLOJM£NT SITE AND SURROUNDING LAND USE

Exposure Nediua

Surface Water

Surface Water

r illinium

Crops

Livestock

Venison

Mechanises of Release

landfill surface runoff/groundwater recharge toBadfisji Creek

Landfill surface runoff/groundwater recharge toGrass Lake

Leaching to groundwater/groundwater transportwithin aquiferGroundwater/surface water usedfor irrigationGroundwater/surface water usedfor irrigation

Ingestion of surface water

Exposure Point Potential Receptor

Off site, Badfiah Creek Residents

Off site. Grass Lake Residents

Off site, private Residentswells

Off site, agricultural Residentsareas

Off site, agricultural ResidentsareasOff site, Badflsh Creek Residents

Route of Exposure

Incidental ingestion,deneal absorption

Incidental ingestion,denasl absorption

Ingestion, denaslabsorption (a)

Ingest ion

Ingestion

Ingestion

PathwayComplete? Quantitatively Evaluated? Basis.

Yes No. Site investigations have shown that groundwaterdoes not recharge into Badf ish Creek, also there isa low potential for surface runoff to the creekas the landfill is well vegetated. Badfish creek isalso the Major discharge for treated effluent frai theMadison sewage treatsttnt plant. Creek waters aresonatiws Bel Oder ous which likely deters activities inthe creek. There is no known fishing in the vicinityof the site.

No No. Site investigations have documented that ground-water flowing frosi City Disposal site does notdischarge into Grass Lake, nor does runoff frosi thesite affect the lake.

Tea res. Residential well data.

Yes No. Groundwater is not used to irrigate crops.Crops are not currently irrigated.

Tes res. On- site monitoring well data.

res No. Deer are not likely to remain in one locationfor a long period of tie*. Therefore their exposureis anst likely such lower than domestic livestockwhich graze in the sane locations daily.

(a) Pathways evaluated for two age groups (children and teens (6-16 years of egel, and adults) unless otherwise noted.

ro

TABLE 19

POTENTIAL EXPOSURE PATHWAYS FOR THE CUT DISPOSAL LANDFILLFUTURE LAND USE CONDITIONS (a)

ExposureMedium

Air

Air

Soil

Soil

Croundwater

Livestock

Mechanisms of Release

Volatilization from thelandfillFugitive dust fromsurface soils

Direct contact withsurface soilsDirect contact uithsubsurface soils

Leaching transport togrounduater/groundwatertransport through theaquifer.

Contaminated grounduater/surface water used to waterlivestock

Exposure Point

On site

On site

On site

On site

On site -private wells

On site/Off site

Potential Receptor

Residents

Residents

Residents

Residents

Residents

Residents

Route of Exposure

Inhalation

Inhalation

Incidental ingestion,denaal absorption

Incidental ingestion,denaal absorption

Ingestion, inhalation ofvolatiles, absorption (b)

Ingestion

PathwayComplete?

Yes

No

Yes

Yes

Yes

Yes

Quantitatively Evaluated? Basis.

Yes. On site soil data and volatilizationand air dispersion modeling.No. It is assumed that the site remainswell vegetated, even if a house is builton site.Yes. Amman hypothetical bouse built onsite. On site surface soil data.

Yes. Potential for redistribution of soilspossible during hypothetical site development.On site grounduater data.Yes. Assumes hypothetical house built onsite. On site grounduater data.

Yes. To be evaluated under current land useconditions. Assumes hypothetical farm builton site.

(a) These are in addition to the present site use pathways.(b) Bermal exposure through indoor water use is expected to be much lower than the lore direct exposures of ingestion and inhalation because of the chemicals' preference for the water

or air phase and the short duration of denaal contact uith tap water.

c

of chemicals in ground water, and ingestion of milk from dairy cattleconsuming groundwater! The receiving media, transport of chemicals within themedia, potential exposure points and exposure routes will be discussed in theBaseline RA for each pathway evaluated. The rationale for selection ofpathways for quantitative evaluation will also be discussed in the BaselineRA.

4.3 Quantification of Exposure Point Concentrations

This section of the baseline risk assessment will quantify exposure pointconcentrations for the selected pathways. Exposure point concentrations foreach pathway will be determined using the RI data. In instances where nosampling data is available, fate and transport models will be applied. Abrief general description of each of the models which we anticipate to be usedin the Baseline RA is provided below.

Ambient air concentrations associated with emissions of volatilechemicals from the landfill will be determined through the use of emissionsand air dispersion models. Emissions from the landfill will be estimatedusing a volatilization model relevant for the site (e.g., Hwang 1986, Karimiet. al. 1987). The model to be used will be determined at a later date. TheIndustrial Source Complex (ISO) air dispersion model will be used to determineair concentrations for off-site receptors. The ISC model is a USEPA approvedand recommended air dispersion model (USEPA 1986d). For on-site receptors(e.g., receptors located on the source of emissions) the ISC model isconsidered inappropriate, therefore a box model will be used to determine theambient air concentrations. Clement International has successfully used the

box model approach for similar applications at a number of USEPA Superfundinvestigations. We will consult with USEPA Region V and WDNR to ensure thatour proposed modeling approach will be acceptable.

Indoor air volatile organic concentrations associated with showering willbe estimated using a model developed by Clement International (Foster and

Chrostowski 1987). We have successfully applied this model at several

43

Superfund sites, including the Fultz Landfill in USEPA Region V. The model isalso recommended by USEPA Region III for use at Superfund sites.

4.4 Estimation of Chemical Intakes

In this section, the intakes of chemicals by potentially exposedpopulations will be calculated. To determine these intakes, assumptionsconcerning chemical concentrations, exposed populations, and exposureconditions such as frequency and duration of exposure, will be used togetherwith intake parameters developed within the section. Tables containingexposure parameters for each pathway will be presented and discussed in detailin the Baseline RA. Tables 20 through 30 present exposure parameters compiledfor each pathway. As discussed earlier and shown in these tables, one

exposure scenario will be evaluated for each pathway. This scenario is thereasonable maximum exposure (RME) case identified by USEPA (1991a, 1989a) foruse in Baseline RAs. Guidance documents prepared by USEPA (1991c, 1989a)present many specific parameter values for the RME scenario. In addition,USEPA Region V has required use of certain values for a similar project(Clement 1991). Where specific values have been provided by these regulatoryagencies, they have been noted and included. In the absence of such guidance,the most relevant and recent scientific literature has been used to developparameter values. An average case exposure scenario will be addressed in theuncertainty section of the Baseline RA (see Section 7.0). The average caseexposure parameter values will be based on data provided in the scientificliterature.

Note that the tables included in this document do not include chemical-specific parameters such as dermal absorption fractions and relative oralbioavailability factors. This information will be provided and discussed in

the Baseline RA.

44

TABLE 20

EXPOSURE PARAMETERS FOR INCIDENTAL INGESTION AND DIRECT CONTACTWITHON-SITE SURFACE SOIL BY SITE TRESPASSERS

CURRENT SITE USE CONDITIONS[Children and Teenagers]

ReasonableMaximum Exposure

Parameters____________________________________(RME)Case_____

Age Period 6-16 Years of Age

Exposure Frequency (days/year) (a) 52

Exposure Duration (years) (b) 10

Soil Ingestion Rate (mg/day) (c) 110Fraction Ingested (dimensionless) (d) 0.25

Skin Surface Area Available for Contact (cm2/day) (e) 3,750

Soil to Skin Adherence Factor (mg/cm2) (f) 1.0Dermal Absorption Fraction (chemical-specific) To be discussed in

Baseline RARelative Oral Absorption Fraction (chemical-specific) To be discussed in

Baseline RA

Body Weight (kg) (g) 40

Lifetime (years) (h)__________________________________70________

(a) Assumes the frequency with which an individual will trespass on the site is influencedby climatic conditions. Listed value provided by P. Van Leeuwen, USEPA Region V.According to USEPA Region V, value assumes individual will trespass on the site 3days/week during June, July, and August and 1 day/week during April, May,September and October.

(b) Assumes children and teenagers from ages 6 to 16 play on the landfill.(c) RMEcase is a weighted average based on USEPA (1991a, 1989a), assuming 1 year

at 200 mg/day and 9 years at 100 mg/day.(d) A time fraction assuming children play on the landfill 4 hours per day. This is divided

by 16 hours/day, the number of waking hours during which exposure could occur(e.g., Calabrese et al. 1989).

(e) Listed value provided by P. Van Leeuwen, USEPA Region V. The value assumes 25%of the body surface area is exposed, and is the median of the USEPA (1991d) valuesfor children (2,500 cm2) and adults (5,000 cm2).

(f) Listed value provided by P. Van Leeuwen, USEPA Region V. It is the default valueprovided by USEPA (1991b).

(g) Calculated from USEPA (1989b).(h) Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is used

in calculating exposures for potential carcinogens.

45

TABLE 21

EXPOSURE PARAMETERS FOR INCIDENTAL INGESTION AND DIRECT CONTACTWITH ON-SITE SURFACE SOIL BY SITE TRESPASSERS

CURRENT SITE USE CONDITIONSVdults]


Parameters____________________________________(RME)Case_____



Soil Ingestion Rate (mg/day) (c) 100

Fraction Ingested (dimensionless) (d) 0.13

Skin Surface Area Available for Contact (cm2/day) (e) 5,000

Soil to Skin Adherence Factor (mg/cm2) (f) 1.0

Dermal Absorption Fraction (chemical-specific) To be discussed in theBaseline RA

Relative Oral Absorption Fraction (chemical-specific) To be discussed in theBaseline RA

Body Weight (kg) (g) 70Lifetime (years) (h)________________________________70_______

(a) Assumes the frequency with which an individual will trespass on the site is influencedby climatic conditions. Listed value provided by P. Van Leeuwen, USEPA Region V.According to USEPA Region V, value assumes individual will trespass on the site 3days/week during June, July, and August and 1 day/week during April, May,September and October.

(b) Based on the upper-bound time at one residence (USEPA 1991, 1989a).(c) Standard default value provided by USEPA (1991a, 1989a).(d) A time fraction assuming adults visit the landfill 2 hours per day. This is divided by 16

hours/day, the number of waking hours during which exposure could occur (e.g.,Calabrese et al. 1989).

(e) Listed value provided by P. Van Leeuwen, USEPA Region V. It is the upper defaultvalue for adults based on USEPA (1991d) assuming 25 percent of skin area isuncovered and exposed.

(0 Listed value provided by P. Van Leeuwen, USEPA Region V. It is the default valueprovided by USEPA (1991b).

(g) Standard default value provided by USEPA (1991a, 1989a).(h) Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is used


TABLE 22

EXPOSURE PARAMETERS FOR INHALATION OFVOLATILE ORGANIC CHEMICALS BY SITE TRESPASSERS

CURRENT SITE USE CONDITIONS[Children and Teenagers]


Parameter__________________________________(RME)Case___

Age Period 6 - 16 Years of Age



Inhalation Rate (m3/hour)(c) 2.2

Exposure Time (hours/day) (d) 4

Body Weight (kg) (e) 40

Lifetime (years) (f)________________________________70______

(a) Assumes the frequency with which an individual will trespass on the site isinfluenced by climatic conditions. Listed value provided by P. Van Leeuwen,USEPA Region V. According to USEPA Region V, value assumes individual willtrespass on the site 3 days/week during June, July, and August and 1 day/weekduring April, May, September and October.

(b) Assumes children and teenagers from ages 6 to 16 play on the landfill.(c) Assumes moderate activity (playing) based on USEPA (1985) age-specific

ventilation rates.(d) Assumes children play on the landfill 4 hours per day.(e) Calculated from USEPA (1989b).(0 Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is

used in calculating exposures for potential carcinogens.

47

TABLE 23

EXPOSURE PARAMETERS FOR INHALATION OFVOLATILE ORGANIC CHEMICALS BY SITE TRESPASSERS

CURRENT SITE USE CONDITIONS[Adults]


Parameter__________________________________(RME)Casc



Inhalation Rate (m3/hour)(c) 0.7

Exposure Time (hours/day) (d) 2

Body Weight (kg) (e) 70

Lifetime (years) (f)________________________________70______

(a) Assumes the frequency with which an individual will trespass on the site isinfluenced by climatic conditions. Listed value provided by P. Van Leeuwen,USEPA Region V. According to USEPA Region V, value assumes individual willtrespass on the site 3 days/week during June, July, and August and 1 day/weekduring April, May, September and October.

(b) Based on the upper-bound tune at one residence (USEPA 1991a, 1989a).(c) Assumes light activity (walking) based on USEPA (1985) adult ventilation rates.(d) Assumes adults visit the landfill 2 hours per day.(e) Standard default value provided by USEPA (1991a, 1989a).(f) Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is


48

TABLE 24

EXPOSURE PARAMETERS FOR INHALATION OFVOLATILE ORGANIC CHEMICALS BY NEARBY RESIDENTS



Parameter

Exposure Frequency (days/year) (a)

Exposure Duration (years) (b)

Inhalation Rate (m /day) (c)

Body Weight (kg) (d)

Lifetime (years) (e)

(RME)Case

350

30

20

70

70

(a) Standard default value provided by USEPA (1991a).(b) Based on the upper-bound time at one residence (USEPA 1991a, 1989a).(c) Standard default value provided by USEPA (1991a).(d) Standard default value provided by USEPA (1991a, 1989a).(e) Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is


49

TABLE 25

EXPOSURE PARAMETERS FOR INGESTION OF GROUNDVVATERBY NEARBY RESIDENTS



Parameter__________________________________(RME)Case___

Exposure Frequency (days/year) (a) 350Exposure Duration (years) (b) 30Ingestion Rate (liters/day) (d) 2Body Weight (kg) (0 70Lifetime (years) (g)________________________________70______

(a) Standard default value provided by USEPA (1991) for ingestion of drinking water.(b) Based on the upper-bound time at one residence (USEPA 1991a, 1989a).(c) Value based on 90th percentile shower time (12 minutes) provided by USEPA

(1989a) with 5 minutes included to account for time spent in the shower room afterthe water is turned off.

(d) Standard ingestion rate provided by USEPA (1991a, 1989a)(e) Value provided by USEPA (1991a) for daily, indoor residential activities.(f) Standard default value provided by USEPA (1991a, 1989a).(g) Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is


Note: No volatile organic chemicals (VOCs) were selected as chemicals of potentialconcern in private wells and as a result, inhalation of VOCs while showering willnot be evaluated in this current site use scenario.

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TABLE 26

EXPOSURE PARAMETERS FOR INGESTION OF DAIRY MILKBY NEARBY RESIDENTS



Parameter________________________________Case (RME)

Exposure Frequency (days/year) (a) 350Exposure Duration (years) (b) 30Ingestion Rate (g/day) (c) 300

Fraction Locally Produced (d) 0.44Body Weight (kg) (e) 70

Lifetime (years) (f)________________________________70______

(a) Standard default value provided by USEPA (1991a).(b) Based on the upper-bound time at one residence (USEPA 1991a, 1989a).(c) Standard default value provided by (USEPA 1991a).(d) Value provided by USEPA (1989b). Assumes that 44% of the total milk consumed

by local farmers comes directly (i.e., no processing or mixing with milk from othersources occurs) from dairy cows raised in the site area.

(e) Standard default value provided by USEPA (1991a, 1989a).(f) Based on USEPA (1991a, 1989a) standard assumption for lifetime. Used for

calculating chronic daily intakes of potendal carcinogens.

51

TABLE 27

EXPOSURE PARAMETERS FOR INCIDENTAL INGESTION AND DIRECT CONTACTWITH ON-SITE SURFACE SOIL BY HYPOTHETICAL RESIDENTS

FUTURE SITE USE CONDITIONS

Parameters


(RME)Case

Exposure Frequency (days/year) (a)Exposure Duration (years) (b)Soil Ingestion Rate (mg/day) (c)Fraction Ingested (dimensionless) (d)

Skin Surface Area Available for Contact (cm2/day) (e)

Soil to Skin Adherence Factor (mg/cm2) (f)Dermal Absorption Fraction (chemical-specific)

Relative Oral Absorption Fraction (chemical-specific)

Body Weight (kg) (g)Lifetime (years) (h) __ __ ___

20230120

1.0

3,750

1.0

To be discussed inBaseline RA

To be discussed inBaseline RA

70

70

(a) Assumes the frequency with which an individual will be exposed to surface soils anddust at the site is influenced by climatic conditions. In this case, relevant climaticconditions refer to those days when the ground is not frozen and/or snow covered, or202 days/year (NOAA1985).

(b) Based on the upper-bound time at one residence (USEPA 1991a, 1989a).(c) Weighted average based on USEPA (1991a, 1989a), assuming 6 years at 200 mg/day

and 24 years at 100 mg/day.(d) Assumes an individual will incidentally ingest soil and dust during all waking hours

and only on site.(e) Listed value provided by P. Van Leeuwen, USEPA Region V. The value assumes 25%

of the body surface area is exposed, and is the median of the USEPA (1991d) valuesfor children (2^00 cm2) and adults (5,000 cm2).

(f) Listed value provided by P. Van Leeuwen, USEPA Region V. It is the default valueprovided by USEPA (1991b).

(g) Standard default value provided by USEPA (1991a, 1989a).(h) Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is used


TABLE 28

EXPOSURE PARAMETERS FOR INHALATION OFVOLATILE ORGANIC CHEMICALS BY HYPOTHETICAL ON-SITE RESIDENTS

FUTURE SITE USE CONDITIONS


Parameter__________________________________(RME)Case



Inhalation Rate (m3/day) (c) 20

Body Weight (kg) (d) 70

Lifetime (years) (e) 70

(a) Standard default value provided by USEPA (1991a).(b) Based on the upper-bound time at one residence (USEPA 1991a, 1989a).(c) Value is a standard default value provided by USEPA (1991a).(d) Standard default value provided by USEPA (1991a, 1989a).(e) Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is


53

TABLE 29

EXPOSURE PARAMETERS FOR INGESTION OF GROUNDWATER ANDINHALATION OF VOLATILES FROM SHOWERING

BY HYPOTHETICAL ON-SITE RESIDENTSFUTURE SITE USE CONDITIONS


Parameter__________________________________Case (RME)



Shower Exposure Time (hours/day) (c) 0.28

Ingestion Rate (liters/day) (d) 2

Inhalation Rate (m3/hour)(e) 0.6

Body Weight (kg) (f) 70

Lifetime (years) (g) 70

(a) Standard default value provided by USEPA (1991a) for ingestion of drinking water.Assumes that residents shower 350 days/year as well.

(b) Based on the upper-bound tunes at one residence (USEPA 1991a, 1989a).(c) Value based on 90th percentile shower time (12 minutes) provided by USEPA

(1989a) with 5 minutes included to account for time spent in the shower room afterwater is turned off.

(d) Standard ingestion rate provided by USEPA (1991a, 1989a)(e) Value provided by USEPA (1991a) for daily, indoor residential activities.(f) Standard default value provided by USEPA (1991a, 1989a).(g) Based on USEPA (1991a, 1989a) standard assumption for lifetime. This value is


54

TABLE 30

EXPOSURE PARAMETERS FOR INGESTION OF DAIRY MILKBY HYPOTHETICAL ON-SITE RESIDENTS

FUTURE SITE USE CONDITIONS[Adults]


Parameter________________________________Case (RME)



Ingestion Rate (g/day) (c) 300Fraction Locally Produced (d) 0.44

Body Weight (kg) (e) 70Lifetime (years) (f) 70

(a) Standard default value provided by USEPA (1991a).(b) Based on the upper-bound time at one residence (USEPA 1991a, 1989a).(c) Standard default value provided by (USEPA 1991a).(d) Value provided by USEPA (1989b). Assumes that 44% of the total milk consumed

by local fanners comes directly (i.e., no processing or mixing with milk from othersources occurs) from dairy cows raised in the site area.

(e) Standard default value provided by USEPA (1991a, 1989a).(f) Based on USEPA (1991a, 1989a) standard assumption for lifetime. Used for

calculating chronic daily intakes of potential carcinogens.

55

5.0 RISK CHARACTERIZATION

In the risk characterization section, the chemical intake estimatesderived in the exposure assessment will be integrated with the dose-responsehealth criteria values. The results of the risk characterization will includeestimates of the upperbound individual cancer risk estimates for potential

carcinogens and a hazard index for nonearcinogens. The individual lifetimeexcess cancer risk for a chemical exhibiting carcinogenic effects will becalculated by multiplying the upper-bound cancer slope factor by the estimatedchronic daily chemical intake averaged over a 70-year lifetime. Fornonearcinogens, potential risks will be calculated by means of a hazard indextechnique, as recommended by USEPA. A hazard index greater than a thresholdlevel of one will trigger a detailed evaluation in which hazard indices forchemicals affecting similar target organs will be calculated. If a targetorgan specific hazard index exceeds one, there may be concern for potentialhealth effects (USEPA 1989a). Risks will be estimated for each exposure

pathway, and where applicable, will also be summed across the exposurepathways in order to estimate the combined impact for individuals who may beexposed via several pathways.

6.0 ECOLOGICAL RISK ASSESSMENT

The ecological risk assessment will evaluate potential risks to aquaticlife and terrestrial animals and plants. The assessment will include fourmajor components: 1) identification of potential receptors, 2) exposureassessment, 3) toxicity assessment, and 4) risk characterization. Potential

receptors will be identified based on contacts with state and federalbiologists, information provided in the RI, and a site visit by Clement staff.

Endangered, threatened, and special status species will be identified.Wetland areas will also be identified. Potential exposure pathways forselected representative species, including livestock, will be evaluated. The

toxicity assessment will identify toxicity reference values for the chemicalsof concern. These values will be used along with estimated exposures tocharacterize potential risks associated with the site. A discussion of theassumptions and ..ncertainties associated with the analysis will be provided.

56

7.0 DISCUSSION OF UNCERTAINTIES

A discussion of the uncertainties in the health risk assessment will alsobe provided. This discussion will focus on the major sources of uncertaintyaffecting the health risk assessment: environmental parameter measurement,fate and transport modeling, estimation of exposure parameters andquantification of exposures, and toxicological data. The impacts of theseuncertainties on the risk estimates presented in the health risk assessmentwill be evaluated. In general, approaches and assumptions will be used thattend to overestimate, rather than underestimate, potential risks.

57

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BOERNGEN, J.G. and SHACKLETTE, H.T. 1981. Chemical Analyses of Soils andOther Surficial Materials of the Contiguous United States. United StatesDepartment of the Interior, Geological Survey. Open File Report 81-197

BUTLER, J.D., BUTTERWORTH, V., KELLOW, S.C., and ROBINSON, H.G. 1984. Someobservations on the polycyclic aromatic hydrocarbon (PAH) content ofsurface soils in urban areas. The Science of the Total Environment.33:75-85

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U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1985a. Development ofStatistical Distribution,or Ranges of Standard Factors Used in ExposureAssessments. Office of Health and Environmental Assessment, Washington,D.C. March 1985. OHEA-E-161

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1985. Water QualityAssessment: A Screening Procedure for Toxic and Conventional Pollutantsin Surface and Ground Water - Part 1. (Revised 1985). EnvironmentalResearch Laboratory, Athens, GA. September EPA/600/6-85/002a

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1986a. Guidelines forCarcinogenic Risk Assessment. Federal Register 51:33992-34003

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1986b. Guidelines forEstimating Exposures. Federal Register 51:34042-34054.

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1986c. Guidelines for theHealth Risk Assessment of Chemical Mixtures. Federal Register 51:34014-34023.

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1986d. Guidelines on AirQuality Models (Revised). Office of Air and Radiation, Research TrianglePark, North Carolina. EPA 450/2-78-027

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1989a. Risk AssessmentGuidance for Superfund. Volume I: Human Health Evaluation Manual.Interim Fir.il. OSWER Directive 9285.7-Ola. September 29, 1989

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U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1989b. Exposure FactorsHandbook. Office of Health and Environmental Assessment, Washington,D.C. July

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1989c. Risk AssessmentGuidance for Superfund -- Environmental Evaluation Manual. InterimFinal. EPA Document 540/1-89/001A. Office of Emergency and RemedialResponse, Washington, D.C.

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1991a. Risk AssessmentGuidance for Superfund. Volume I: Human Health Evaluation ManualSupplemental Guidance. Standard Default Exposure Factors. InterimFinal. Washington, D.C. OSWER Directive 9285.6-03. March 25, 1991.

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1991b. Review of Notes for theTechnical Workplan: Baseline Risk Assessment for the Powell RoadLandfill Site, Dayton, OH. Memo from P. Van Leeuwen, USEPA Region VToxicologist to K. Tindall, USEPA Region V Remedial Project Manager.June 3, 1991

U.S. ENVIRONMENTAL PROTECTION AGENCY (USEPA). 1991c. Letter from K. Tindall,USEPA Region V Remedial Project Manager to T. Kern, Waste Management ofNorth America. June 7, 1991. Regarding the Powell Road Landfill Site,Dayton, OH

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