NCD003200383_19920717_Koppers Co. Inc._FRBCERCLA RISK_Baseline Risk Assessment-OCR

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July 17, 1992
Ms. Barbara Benoy
U.S. EPA Region IV
345 Courtland Street, NW
Atlanta, GA 30308
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Re: Baseline Risk Assessment for the Former Koppers Company, Inc. Site, Morrisville,
NC
Dear Barbara:
On behalf of Beazer East, Inc., we are submitting to you five copies of the final pages of the
Baseline Risk Assessment for the Former Koppers Company, Inc. Site in Morrisville, NC.
These pages reflect the changes agreed to by Beazer and EPA in response to EPA's
comments dated July 14, 1992. The enclosed pages should replace the corresponding
pages in the July 1992 version of the document (submitted to EPA on July 2, 1992). We
understand that the replacement of these pages now makes the document a final draft. We
are also submitting two copies of these changed pages to the State of North Carolina
DEHNR.
We hereby request these pages, with the rest of the report, be docketed and made part of
the Administrative Record for the Morrisville, NC Site. If you have any questions about the
responses to comments, please do not hesitate to call me or Shannon Craig at Beazer
East, Inc.
Sincerely,
A _/ 'i,7//
1) {( vc µ{11 te, ~
/ -V / Susan L. Allen,
Project Manager
cc: S. Craig, Beazer
W. Giarla, Beazer
J. Mitsak, Keystone
1p:·DeRosa;-NC-DEHNR---q
0542742.SLA, 0845-008-800
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CONTENTS
(Cont'd)
6.5.3.1 Muskrat Characterization ......................... 6-21
6.5.3.2 Belted Kingfisher Characterization ................... 6-21
6.6 Ecological Evaluation Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21
7.0 SOURCES OF UNCERTAINTY ....................................... 7-1
7.1 Uncertainties Associated with Human Health Evaluation ................. 7-1
7.1.1 Hazard Identification ..................................... 7-1
7.1.2 Dose-Response Assessment ............................... 7-1
7.1.2.1 Animal-to-Human Extrapolation in Noncarcinogenic Dose-
Response Evaluation ............................. 7-2
7.1.2.2 Evaluation of Carcinogenic Dose-Response ............. 7-2
7.1.2.3 Compound-to-Compound Extrapolation .. , . . . . . . . 7-5
7.1.3 Exposure Assessment .................................... 7-5
7.1.3.1 Estimation of Exposure Point Concentrations ............ 7-5
7.1.3.2 Estimation of Exposure Dose ....................... 7-6
7.1.4 Risk Characterization .................................... 7-7
7.1.4.1 Risk from Multiple Compounds ...................... 7-7
7.1.4.2 Combination of Several Upper-bound Assumptions ....... 7-8
7.1.5 Summary of Sources of Uncertainty in the Human Health Evaluation .. 7-9
7.2 Uncertainties Associated with the Ecological Evaluation 7-9
8.0 SUMMARY AND CONCLUSIONS ..................................... 8-1
8.1 Human Health Evaluation Summary ................................ 8-1
8.2 Ecological Evaluation Summary ................................... 8-2
8.3 Baseline Risk Assessment Summary ............................... 8-2
9.0 CLEAN-UP LEVELS EVALUATION ................................... 9-1
9.1 Derivation of Risk Based Target Clean-up Levels (RBTCLs) .............. 9-1
9.1.1 Human Health Evaluation ................................. 9-2
9.1.2 Ecological Evaluation .................................... 9-3
9.2 Comparison of RBTCLs and ARARs ............................... 9-3
9.3 Summary and Recommendations 9-6
REFERENCES
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CONTENTS
(Cont'd}
APPENDICES
A HAZARD IDENTIFICATION AND SUPPLEMENTAL DATA ANALYSIS
A-1 HAZARD IDENTIFICATION
B
A-2 SUPPLEMENTAL DATA ANALYSIS
DOSE-RESPONSE SUMMARIES
C ABSORPTION ADJUSTMENT FACTORS
C-1 ABSORPTION ADJUSTMENT FACTORS
C-2 DERIVATION OF INHALATION FACTORS
C-3 SKIN PERMEABILITY CONSTANTS
D REVIEW OF THE SCIENTIFIC LITERATURE
E ADDITIONAL EXPOSURE ASSESSMENT INFORMATION
E-1 CONSTITUENT FATE AND TRANSPORT
E-2 HYPOTHETICAL VEGETABLE INGESTION SCENARIO
EN3t
E-3 HYPOTHETICAL ON-SITE RESIDENTIAL USE OF GROUND WATER DURING
SHOWERING
E-4 EXPOSURE SPREADSHEETS (SEPARATE DOCUMENT}
F ECOLOGICAL EVALUATION -ADDITIONAL INFORMATION
F-1 HABITAT AND WILDLIFE SURVEY
G
F-2 CALCULATION OF POTENTIAL EFFECTS TO MUSKRAT
F-3 CALCULATION OF POTENTIAL EFFECTS TO BELTED KINGFISHER
F-4 EVALUATION OF POTENTIAL EFFECT ON THREATENED, RARE, OR
ENDANGERED SPECIES
ADDITIONAL CLEAN-UP LEVELS EVALUATION INFORMATION
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potential exp·osure to constituents by muskrats inhabiting Fire Pond was 0.11 which falls at the
extreme lower end of the range of "possible concern" defined by EPA. The toxicity quotient
calculated for the belted kingfisher was 0.60, which is also at the extreme lower end of the range
of "possible concern" defined by EPA.
Clean-up Levels Evaluation
The results of the aquatic ecological evaluation in Fire Pond and Medlin Pond indicate that certain
constituents pose "possible concern", as defined by EPA, to aquatic receptors. Our constituent,
dioxin, was of "high concern", as defined by EPA, for aquatic receptors assumed to be exposed
to surface water in Fire Pond. The toxicity screening values used to estimate the potential risk
to aquatic receptors in the surface water of these ponds were provided by EPA Region IV, and
are intended for screening purposes only. Because the screening showed several constituents
resulted in toxicity quotients of "possible concern" in Fire Pond and Medlin Pond, and one of "high
concern" in Fire Pond, the surface water in Fire Pond and Medlin Pond were identified as media
possibly requiring remediation at this Site.
A :\P UBS\PAOJE GTS\084 5008\51 O. ES ES-11 July, 1992
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Area, the Fire Pond, and the Former Lagoon and Cellon Treatment Process Areas). Beazer
Materials and Services, Inc. entered into discussions concerning a Consent Order with EPA
Region IV in December 1988, and signed the Consent Order on March 14, 1989.
As previously stated, the Morrisville Site is the location of a current laminating facility and a former
wood treating process, referred to as the Cellon process. The plant has produced glued-
laminated wood products since 1962. The Cellon process was operated from 1968 to 1975, at
which time it was dismantled. Waste water from the Cellon process settled in on-Site effluent
lagoons. Environmental investigations undertaken in the late 1970s and early 1980s revealed
pentachlorophenol present in on-Site ground water wells. On-Site soil removal was undertaken
in 1980 and 1986.
Sampling of on-Site soils, surface water and ground water was conducted at various times
throughout the late 1970s and 1980s. In August 1987, Keystone prepared a report entitled
"Summary of Existing Data for Previously Operated Property, Koppers Company, Inc., Raleigh,
North Carolina Site." This report, which was submitted to the North Carolina Department of
Environment Health and Natural Resources (NCDEHNR), summarizes previous environmental
investigations of ground water, surface water, sediments, and soils at the Site.
In addition to on-Site ground water monitoring, Beazer East, Inc. initiated a domestic well
sampling program of potentially affected wells in 1986. Results of this sampling indicate the
presence of very low levels of pentachlorophenol and isopropyl ether in domestic wells located
generally to the north and northwest of the Site.
Pursuant to an agreement with the Wake County Department of Health and the State of North
Carolina, Beazer has provided an alternative potable water supply to any resident who owns/or
uses a well in which any level of pentachlorophenol or isopropylether was detected. Beazer has
carried out its agreement by installing approximately three miles of water line to provide a public
water supply for affected residents. In 1989 Beazer entered into an Administrative Consent Order
with EPA for the installation of the water line.
The RI report presents the results of the investigation of potential ground water source areas on
the Site. Phenolics, principally pentachlorophenol, and dioxins/furans have been detected in on-
Site surface and subsurface soils, with the highest pentachlorophenol concentrations occurring
in the Former Lagoon and Eastern Areas. Surface water and sediment sampling conducted in
the Fire Pond, Medlin Pond (off-Site), and associated drainage ditches showed pentachlorophenol
and dioxins/furans concentrations above detectable levels in both media. The RI fully
characterizes the potential areas of interest at the Site. This baseline risk assessment is based
on the results of the RI.
R:\P UBS\ PAOJ E CT S\0845008\51 O.S 1 1-3 July, 1992
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0-.5 2-4
238 U 123 U
887 ND
540 1. 1
Source: Keystone, 1992
0-.5 1.5-3.5
286 U 122 U
1590 178
1000 5.9
LEGEND
* -SEDIMENT SAMPLE LOCATION
o-.5
232
411
26
ND
NA
-DEPTH (FEET)
-PENTACHLOAOPHENOL {~g/Kg)
-TOTAL ACID EXTRACTABLE PHENOLICS (~g/Kg)
-2,3, 7, 8-TCD□ EQUIVALENT CONCENTRATION (ng/Kg)
-NOT DETECTED (ALL INDIVIDUAL PHENOLIC CONSTITUENTS
WERE BELOW THEIR RESPECTIVE DETECTION LIMITS)
-NOT ANALYZED
U -ANALYTE NOT DETECTED AT THE CONCENTRATION LEVEL SHOWN
6/4/90
0-.5
350 U
NO
890
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10/18/90
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1-1.5
168 U I
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974
590
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SCALE (FEET)
0 30 60
S36
APPROX.
BOO'SOUTHEAST ~------,,.,,. ~~
~ 0-.5
232 U
411
26
Q
FIGURE 2-10
Sediment Water Quality in Medlin Pond and Medlin Pond Discharge Streams
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The estimated potential upper-bound excess lifetime cancer risk for use of on-Site ground water
as potable water supply by hypothetical future on-Site residents in Area D (1.48E-07, Table 5-16)
is less than the EPA's point of departure risk of 1 E-06, indicating that, based on risk, remediation
of the on-Site ground water in the Western Area of the Site is not needed. Only the estimated
potential upper-bound excess lifetime cancer risks associated with hypothetical future potable use
of ground water in Areas A and B (Eastern Area), and C (Former Lagoon and Cellon Process
Area), exceed the EPA's target risk range of 1 E-06 to 1 E-04 (Tables 5-13, 5-14, 5-15). Because
estimated upper-bound assumed risks are assumed to be additive, the estimated total upper-
bound cancer risks for hypothetical on-Site residents in these areas also exceed the target risk
range. In Areas A and B, the Eastern Area, the majority of the estimated potential assumed risks
are associated with exposure to dioxins and furans (Tables 5-13 and 5-14).
As discussed above, because surrounding off-Site residents are currently using city water as a
potable water supply and the Site is also currently supplied by city water lines, it is likely that the
hypothetical on-Site future residents would also use city water, and not ground water as a potable
water supply.
Potential residential exposures to constituents in ground water via inhalation of volatiles while
showering results assumed risks well below EPA's point of departure. Thus, assumed risks from
exposure to on-Site ground water while showering are not of concern at this site.
5.3 Summary of Estimated Potential Assumed Risks
This baseline risk assessment has shown that no potential adverse assumed noncarcinogenic
health risks are expected to occur following potential exposure to constituents in any of the
environmental media evaluated (surface soils, subsurface soils, sediments, surface water, fish and
ground water). The baseline risk assessment has also shown that, with the exception of potential
exposure to surface soil in Area C, hypothetical future use of on-Site ground water as a potable
water supply, and hypothetical future use of Fire Pond as a swimming hole and source of fish for
consumption by hypothetical on-Site residents (which is an unlikely occurrence), the estimated
potential assumed risks associated with all PEPs fall within or below the U.S.EPA's target risk
range.
Section 8.0 presents recommendations for remediation of certain media at the Site based on
ssumed risk. Section 9.0 compares risk-based target clean-up levels with standards and other
applicable and relevant or appropriate requirements (ARARs). In some cases, although
remediation may not be required based on assumed risk, recommendations for remediation may
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6.0 ECOLOGICAL EVALUATION
This Section reports the results of the ecological evaluation for the Former Koppers Company,
Inc. Site in Morrisville, North Carolina. The ecological evaluation is part of the baseline risk
assessment for the Site. This evaluation was prepared using the following EPA guidance
documents: Risk Assessment Guidance for Superfund: Volume II, Environmental Evaluation
Manual (U.S. EPA 1989e), Recommendations for and Documentation of Biological Values for Use
in Risk Assessment (U.S. EPA, 1988a); Quality Criteria for Water, 1986 (U.S. EPA, 1986b);
Review of Ecological Risk Assessment Methods (U.S. EPA 1988b); and Ecological Assessment
at Hazardous Waste Sites (U.S. EPA, 1989a). Although formal guidance for evaluating potential
ecological effects from a site is not presented in the available guidance documents, the
documents do provide an overall framework for evaluating environmental effects. Despite the
absence of formal guidance, a scientifically defensible and appropriate approach for the
evaluation of potential ecological effects is presented here.
The first step of this ecological evaluation is the characterization of the Site and surrounding area,
and is presented in Section 6.1. This is followed by the selection of the indicator species in
Section 6.2 and the selection of constituents of potential interest in Section 6.3. Section 6.4
describes the aquatic assessment in which potential effects in aquatic species are characterized.
Section 6.5 describes the riparian assessment in which potential effects in mammals and birds
are characterized. Conclusions of the ecological evaluation are summarized in Section 6.6 and
Section 8.2 of the baseline risk assessment.
In addition to the analysis presented in this section, Appendix F contains additional information
for the ecological evaluation. Appendix F-1 discusses the Wildlife and Habitat Survey; Appendix
F-2 presents the Calculation of Potential Effects to Muskrat; Appendix F-3 presents the
Calculation of Potential Effects to Belted Kingfisher; and Appendix F-4 discusses the Evaluation
of Potential Threatened, Rare or Endangered Species.
A :\P UBS\P ROJ E CTS\0845008\51 0. S6 6-1 Ju~. 1992
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For 2,3,7,8-TCDD (dioxin), the LOEL guidance values for the protection of freshwater aquatic life
were derived on the basis of fish consumption rates for humans (U.S. EPA, 1984). EPA derived
these guidance values for dioxin by comparing calculated freshwater fish concentrations with U.S.
Food and Drug Administration (FDA) health advisories. The FDA health advisories determined
concentrations of dioxin in fish that are considered acceptable for human consumption. The
LOELs for dioxin that EPA lists as guidance values were back-calculated from the fish dioxin
concentrations determined by FDA and an assumed dioxin BCF of 5000. Thus, the LOEL
guidance values are not a direct measure of the potential toxicity of dioxin to fish. The AWQC
document on dioxin, however, does list some data on the toxicity of dioxin to aquatic species.
The dioxin AWQC document presents the following information: "the available information
indicates that acute values for some freshwater animal species are> 1.0 ug/I; some chronic values
are <0.1 ug/I, and the chronic value for rainbow trout is <0.001 ug/I" (U.S. EPA, 1984). Therefore,
Table 6-2 lists the acute value for dioxin as 1.0 ug/I and the chronic value as 0.001 ug/1. These
data are scientifically appropriate and defensible as they are based on toxicity studies on aquatic
organisms rather than back-calculated from FDA health advisories for potential human exposure.
The Water Management Division of EPA Region IV has developed screening values which were
initially provided to permit writers in order to assist them in the evaluation of wastewater
discharges (U.S. EPA, 1991c). These screening values have been adopted by the Region IV
Superfund Program for use in the initial screening of ambient surface water data (U.S. EPA,
1992). The values were derived from published EPA ambient water quality criteria documents
with safety factors applied. A safety factor of ten is used when the data concerning the acute
toxicity of a compound to aquatic organisms are limited. A safety factor of ten is also applied to
acute aquatic toxicity data to derive chronic toxicity values when these are not available. These
acute and chronic toxicity values are designed to be used for screening purposes and they are
included in Table 6-2.
Pentachlorophenol values are pH dependent. The values recommended by EPA for
pentachlorophenol are based on a pH of 6.0 for both the acute and chronic criteria. As reported
by U.S. EPA Region IV (U.S. EPA, 1992), the screening criteria recommended by Region IV need
to be adjusted using the relationship presented in the AWQC for pentachlorophenol to reflect the
pH of the surface water bodies on and near the Site. In order to address this issue, pH data from
surface water at and near the Site were obtained. The pH values for Fire Pond and Medlin Pond
are reported in Table 6-3. (These pH data come from Table 4-35 of the RI report.)
Using the relationship from the AWQC for pentachlorophenol, acute and chronic criteria values
were calculated for each of the pH values presented in Table 6-3. To develop appropriate acute
criteria values, the lowest calculated concentration for Fire Pond (4.27 ug/L) and Medlin Pond (8.2
ug/L) are selected as acute criteria for pentachlorophenol for the revised risk assessment.
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To develop appropriate chronic criteria values, the lower average of the Round 1 or Round 2 data
for Fire Pond and Medlin Pond were selected. Round 1 and Round 2 data were collected at
different times during the year. To be conservative the lower average values were used in the
evaluation of potential chronic effects. This results in a calculated chronic criteria value for
pentachlorophenol for Fire Pond of 4.91 ug/L and for Medlin Pond of 10.14 ug/L.
From the data in Table 6-2, benchmark concentrations were selected for the evaluation of bluegill
as an indicator species. In order to be conservative, the lowest value among the acute AWQC
or LOEL guidance value, the bluegill acute LOEL or the EPA Region IV screening acute value
was selected as the acute benchmark concentration. Because there were no chronic LOELs
specific to bluegill, the lower value between the chronic AWQC or LOEL guidance value or the
EPA Region IV screening chronic value was selected as the chronic benchmark concentration.
No chronic values were available for 2,3,5,6-tetrachlorophenol. Therefore, following EPA Region
IV guidance, a safety factor of 1 O was applied to the acute value of 140 ug/L to derive a chronic
value of 14 ug/L.
6.4.2 Exposure Evaluation
Bluegills are assumed to inhabit the suriace water bodies of Fire Pond and Medlin Pond. As
aquatic species, bluegill are potentially exposed to constituents dissolved in water and to
constituents bound to sediments or suspended solids.
Aquatic species may be exposed to constituents in the water through water ingestion, uptake
through the gills, dermal absorption, and ingestion of food or suspended solids. The extent of
their exposure to various constituents will, in part, depend on the movement of the constituents
through the water column. An important characteristic that influences the concentration of
constituents in the water column and bottom sediments is the hydrophobic nature of the
constituent. Hydrophilic constituents will tend to stay dissolved in the water column while
hydrophobic constituents may adsorb to suspended solids in the water column or accumulate in
the bottom sediments.
Benthic organisms and other aquatic species that live in close association with sediments may
potentially be exposed to constituents in the sediments through ingestion and dermal absorption.
Constituents in the sediments may be bound to individual sediment particles or dissolved in
interstitial water. Because of the lack of appropriate ecotoxicological data in this area, this
exposure route is not estimated for aquatic species in this evaluation.
In evaluating the potential for acute toxicity effects, it was conservatively assumed that the
receptor contacts the maximum constituent concentration in the surface water for four days of
A :\PU BS\P ROJ E CTS\0845008\51 0.S6 6-10 July, 1992
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continued exposure. This is a conservative assumption because the medium is fluid, the
measured constituent concentrations will mix and not remain steady, and it is unlikely that a
receptor would be exposed to the maximum measured concentration of each constituent detected
in the surface water for a prolonged period of exposure. In evaluating the potential for chronic
toxicity effects, it was assumed that the receptor is continuously exposed to the mean
concentration of the constituent in surface water.
6.4.3 Characterization of Potential Aquatic Impacts
In this assessment, the potential for assumed adverse effects in aquatic biota is estimated by the
toxicity quotient method prescribed by EPA (U.S. EPA, 1988b, ORNL, 1986). This method
involves the derivation of a toxicity quotient which is the ratio of an expected environmental
concentration (EEC) to a measured toxicological benchmark concentration (BC).
Toxicity Quotient (unit/ass) = EEC(,µg/L)
BC(,µg/L)
The resulting ratio is arbitrarily classified as being of "no concern" if less than 0.1, of "possible
concern" if between 0.1 and 10, and of "high concern" if the ratio is greater than 1 O (U.S. EPA,
1988b}. No documentation has been provided for the rationale behind these classifications.
Acute and chronic toxicity quotients were calculated for the constituents in Fire Pond and Medlin
Pond. The acute benchmark concentrations were compared to the maximum observed
environmental concentrations measured for each of the constituents in Fire Pond and Medlin
Pond to generate the acute toxicity quotients presented in Table 6-4. The chronic benchmark
concentrations were compared to the mean observed environmental concentrations measured
for each of the constituents in Fire Pond and Medlin Pond to generate the chronic toxicity
quotients presented in Table 6-5.
The acute toxicity quotients for each of the constituents in Fire Pond and Medlin Pond were all
less than 0.1, which fall in the range of "no concern" as defined by EPA (U.S. EPA, 1988b). For
Fire Pond, the chronic toxicity quotients for each of the constituents, except TCDD-TE, were all
less than 0.1, which fall in the "no concern" range defined by EPA (U.S. EPA, 1988b).
The chronic toxicity quotient for TCDD-TE in Fire Pond is 16.5 which falls in the range of "high
concern" as defined by EPA (1988b). This value was obtained using the EPA Region IV chronic
screening value which contains a safety factor of 10. This value was derived from the ambient
water quality document for dioxin. The value is based on the value 0.0001 ug/L which comes
R :\P UBS\PROJE CTSl()84 5008\51 O.S6 6-11 July, 1992
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from a 96 hour test on northern pike embryos and the resulting effect was "slight reduction in
growth up to 21 days". A safety factor of ten was applied to the northern pike value of 0.001 ug/L
to yield the value 0.00001 ug/L.
The National Criteria section of the Ambient Water Quality Criteria {AWQC) for dioxin states that
the chronic value for rainbow trout is 0.001 ug/L. This value was considered appropriate for this
assessment and results in a toxicity quotient of 0.165. The EPA has chosen to use a safety
factor of ten "when limited information concerning aquatic toxicity of a compound is available."
Applying a safety factor of ten as suggested in the comments from EPA yields a chronic value
of 0.0001 ug/L, and a chronic toxicity quotient of 1.65 which is at the low end of the range of
"possible concern".
EPA's AWQC for dioxin are based upon 2,3,7,8-TCDD. This congener was not detected in
surface water in Medlin and Fire Ponds, however, other, higher chlorinated congeners were
detected. In order to compare measured concentrations of the higher chlorinated congeners to
the AWQC, their concentrations were converted to 2,3,7,8-TCDD equivalents using Toxic
Equivalency Factors (TEFs) derived for humans. These factors may not be appropriate for
aquatic species, because specific toxicity testing to derive TEFs has not been done for aquatic
species .
Chronic toxicity quotients for Medlin Pond were less than 0.1 for phenol; 2-nitrophenol; 2,4-
dimethylphenol; 2,4-dichlorophenol; and pentachlorophenol indicating "no concern". As shown
in Table 6-5, chronic toxicity quotients for 2,4,6-trichlorophenol; 2,4-dinitrophenol; 2,3,5,6-
tetrachlorophenol; 2-methyl-4,6-dinitrophenol and 2,3,7,8-TCDD were in the low end of the range
of "possible concern" as defined by EPA.
6.5 Riparian Assessment
The riparian assessment quantifies the potential impact of the Site on mammalian and avian
receptors (muskrat and belted kingfisher) through exposure through the food chain. The
estimated average daily dose for the receptor is compared to an acceptable dose in a manner
similar to the hazard index approach used for humans and the toxicity quotient method used for
aquatic species. The toxicity or dose-response information is discussed in Section 6.5.1, and the
exposure evaluation is presented in Section 6.5.2. The characterization of potential effects is
found in Section 6.5.3.
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6.5.1 · Dose-Response Evaluation
Ideally, the units of concern in ecological risk assessments are populations or higher categories
such as communities or ecosystems. However, neither the theoretical underpinnings nor the
technical methodologies have been developed to carry out such analyses. EPA Region IV is
currently attempting to develop ecological risk assessment guidance, but until such time as these
methods are developed, individual assessments of exposed indicator species will be utilized.
Field data on the toxicological effects of constituent exposure to indicator species are difficult to
interpret. Only under laboratory conditions can doses and exposures be controlled and quantified.
Most of the data on natural populations are collected without any information on the
environmental dose or the conditions under which the exposures occurred. Usually the exposure
dose which resulted in an observed toxicological effect in the field is not quantifiable and therefore
is of limited utility in determining a species-specific dose-response value. The majority of data
used by the EPA to derive human reference doses and cancer slope factors are based on
mammalian studies from which the data are extrapolated to humans. In this evaluation, dose-
response values were derived for muskrat and belted kingfisher using the supporting literature
for EPA-derived human reference doses and other relevant literature sources. The derivation of
these values is explained in the following subsections.
6.5.1.1 Mammalian Dose-Response Values
Oral noncarcinogenic dose-response values for mammalian species are developed on the basis
of the toxicity studies used to determine the EPA-derived human oral reference doses. The
laboratory animal species and the type of study used to derive the human oral reference dose
are identified. Safety factors are then applied as necessary to extrapolate from a subchronic •
study to a chronic study, or from a Lowest Observed Adverse Effect Level (LOAEL) to a No
Observed Adverse Effect Level (NOAEL) in order to obtain an oral dose-response value that is
applicable to mammals.
If the EPA-derived human oral reference dose was not based on a laboratory animal study, then
other literature sources are examined for mammalian toxicity studies. The most applicable
experimental data would be a chronic NOAEL for the indicator species or an equivalent laboratory
animal. However, if no NOAEL is available, a subchronic study or LOAEL is located. In either
case, appropriate uncertainty factors are applied in order to derive an oral dose-response value
that is applicable to mammals. The constituent-specific oral noncarcinogenic dose-response
values derived for the muskrat are summarized in Table 6-6.
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· 6.5.1.2 Avian Dose-Response Values
Dose-response information for the effects of dioxin on the kingfisher was not located in the
available scientific literature. Therefore, available toxicological literature on other avian species
was used. ENSR (1989) studied the effects of dioxin in the eastern bluebird and found a No
Observed Adverse Effect Level (NOAEL) for bluebird embryonic toxicity of 1,000 pg dioxin/g egg.
The NOAEL was back-calculated through the following equations to obtain the estimated dioxin
body burden for the bluebird. The bird-to-egg translocation factor is estimated as 4.8 percent
(0.048), the average weight of the eastern bluebird egg is 3 grams, and the average female
bluebird body weight is 34 g (0.034 kg) (ENSR, 1989). Using this information, the following
relationships are applied to calculate the steady state dioxin body burden for the female bluebird
which would result in a NOAEL level of 1000 pg dioxin/g egg.
The research that was cited as ENSR (1989) has also been reported in the 1988 proceedings of
the TAPPI conference (Thiel et al., 1988).
Additional values have been reported for potential effects of dioxin to avian species. Kubiak et
al. (1989) reported on effects to tern eggs from a test site at Green Bay in Michigan in
comparison to tern eggs from the control site at Lake Poygan in Michigan. Verrett (1970; as cited
in Kubiak et al., 1989) reported that 10 to 20 pg/g of 2,3, 7,8-tetrachlorodibenzo-p-dioxin in chicken
eggs produced embryotoxicity, edema, and deformities. Dose-related increases in cardiovascular
malformations of chick embryos were reported by Cheung et al. (1981; as cited in Kubiak et al.,
1989), observing a 20 percent increase in malformations at a dosing level of 6 pg/g and a
doubling of malformations at 65 pg/g.
The Kubiak study reported a level of 201 pg TCDD-TE/g egg in tern eggs from the control site
at Lake Poygan in Michigan and a level of 2175 pg TCDD-TE/g egg in tern eggs from the test site
at Green Bay in Michigan. Both levels are considerably higher than the results, also reported in
Kubiak et al.(1989), of Cheung et al. (1981) who reported cardiovascular malformations "at a
dosing level of 6 pg/g" for domestic chick embryos. Other effects reported included
subcutaneous edema, crossed beaks, and stunted, malformed legs. Kubiak et al. also report on
unpublished data from Verret that "as little as 10 to 20 pg/g of 2,3,7,8-TCDD in chicken eggs
produced embryotoxicity, edema, and deformities." Additional unpublished data from Verret was
used to develop an LD50 for chicken embryo of 140 pg/g. Kubiak et al. then report that these and
other symptoms are similar to the results reported for the Green Bay site (2175 pg TCDD-TE/g
egg) in their research but not observed at the control site at Lake Poygan. No discussion was
presented by Kubiak et al. as to why domestic fowl appear to be more sensitive than wild tern
populations sampled in this report. Eisler (1986) noted that domestic chickens were relatively
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sensitive to dioxin, and this observation supports the hypotheseis that domestic fowl may not
represent conditions that are found in wild populations.
The results reported by Thiel et al. (1988) involved both laboratory and field studies. The
laboratory studies also looked for effects similar to those reported by Verret and Cheung et al.,
as cited in Kubiak et al.(1989). That is, the researchers specifically looked for evidence of
subcutaneous edema and ascites formation. These are two of the effects identified by Kubiak
et al.(1989). No subcutaneous edema or ascites formation was detected in the controls or any
of the treatment groups less than, or equal to, 1,000 pg TCDD/g egg. If responses are seen at
the levels reported in the articles cited in Kubiak et al.(1989), then severe reductions in hatching
and fledging success should have been observed both in the Thiel et al. ( 1988) report and at the
control site of the Kubiak et al. (1989) study. However, no reductions in survival or other effects
were observed when compared to controls.
Both Thiel et al. (1988) and Kubiak et al. (1989) can be used to estimate no effect levels that are
considerably higher (1,000 and 200 pg TCDD-TE/g egg, respectively) than the no effect levels
of Verret and Cheung et al. cited in the Kubiak et al. (1989) study. Kubiak et al. (1989) note that
the effects observed by Verret and by Cheung et al. were observed at the Green Bay site, but
not at the control site at Lake Poygan. Using the no effect level of Thiel et al. (1988) of 1,000 pg
TCDD-TE/g egg would be protective, but use of the more conservative field results of Kubiak et
al. (1989) indicating a no effect level of 200 pg TCDD-TE/g egg would be more conservative and
would result in additional protection. Therefore, the value 200 pg TCDD-TE/g egg was used in
this evaluation.
Dioxin concentration in egg = dioxin per gram of egg (pg dioxin/g egg) x egg weight (g/egg)
= 200 pg dioxin/g egg x 3g/egg = 600 pg dioxin/egg
Dioxin concentration in bird (pg dioxin/bird) = dioxin in egg (pg dioxin/egg)/bird-to-egg
translocation factor [(pg/egg)/(pg/bird)]
= 600 (pg dioxin/egg)/0.048[(pg/egg)/(pg/bird)]
= 12,500 pg dioxin/bird
Dioxin concentration in bird (pg dioxin/kg bird) = dioxin in bird (pg dioxin/bird)/bird body
weight (kg bird)
= 12,500 (pg dioxin/bird)/0.034 (kg bird)
= 367,647 pg dioxin/kg bird = 3.68E-04 mg dioxin/kg bird
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Thus, it is estimated that the female bluebird body burden of 3.68E-04 mg dioxin/kg bird will result
in a NOAEL for bluebird embryonic toxicity of 200 pg dioxin/g egg. This dose response value is
assumed to be protective of other avian species and is applied to the belted kingfisher in this
ecological evaluation.
6.5.2 Exposure Evaluation
Indicator species may be potentially exposed to constituents through air, soil, surface water,
sediments, ground water, and the food chain. The selection of pathways for analysis depends
upon the Site conditions, the biology of the species, and the ecological evaluation methodology.
The potential exposure pathways for the muskrat and the belted kingfisher are described in the
following subsections.
6.5.2.1 Muskrat Exposure Evaluation
Muskrats are semiaquatic rodents that may potentially inhabit the Site. They are a very territorial
species and usually live alone or with their mates (Chapman and Feldhamer, 1982). The area
occupied by a muskrat is dependent upon the size, configuration, and diversity of aquatic habitat;
social pressures; and environmental conditions. Under normal conditions, a muskrat will typically
move to a new area each spring (Chapman and Feldhamer, 1982). In this evaluation, muskrats
are assumed to spend three years of their 4-year lifespan in Fire Pond. This assumes that a one-
year old muskrat migrates to Fire Pond, establishes a lodge, and remains at this location for the
remainder of its lifetime. Once at Fire Pond, the muskrat is assumed not to migrate away from
the Site. This is a conservative exposure scenario for the muskrat, as it is unlikely that a muskrat
will inhabit the same lodge for more than a year (Godin, 1977). The muskrat is assumed to be ·
potentially exposed to constituents in Fire Pond through water ingestion, inadvertent sediment
ingestion, and ingestion of aquatic plants. Calculation of the potential exposure dose through
these potential exposure pathways is described in detail below.
Water Ingestion
Potential exposure through the ingestion of water is estimated using the following equation:
Lifetime Average Daily Dose (mg/kg-day) = Constituent concentration in water (mg/L) x
Water ingestion rate (Uday) x Oral Absorption Adjustment Factor
(unitless) x Exposure frequency (days exposed/365 days) x Exposure
duration (years/years exposed) / Body weight (kg)
The constituent concentrations in Fire Pond surface water, presented in Table 2-5 of the baseline
risk assessment, are used in this evaluation. In the absence of a published water ingestion rate
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for the muskrat, this parameter was estimated from available mammalian literature. Data from
Robbins (1983) indicate that water turnover rates of wild mammals is a function of body weight.
The water turnover rate for wild mammals weighing approximately 1 kg is approximately 100 mis,
estimated from a figure presented in Robbins (1983). Turnover rates for animals fed water ad
libitum may reflect a level of water intake that is above their minimum needs (Robbins, 1983).
Thus, the ingestion rate for the muskrat is conservatively assumed to be 0.1 liters. Muskrats are
assumed to obtain their entire drinking water requirement from Fire Pond every day for three
years. The average body weight of the muskrat is 1.4 kg (Burt and Grossenheider, 1976).
Absorption Adjustment Factors (AAFs) used in this assessment are the same AAFs as used in
the human health assessment (See Table 4-2).
Plant Ingestion
Muskrats typically consume a diet of aquatic plants such as pondweed, cattails, duckweed, and
water lilies. They may also eat insects, frogs, snails, minnows, and young birds. This
assessment assumes that the muskrat only consumes aquatic plants growing in Fire Pond.
Potential exposure through plant ingestion is calculated using the following equation:
Lifetime Average Daily Dose (mg/kg-day) = Constituent concentration in sediment (mg/kg)
x Root uptake factor x Plant ingestion rate (kg/day) x Oral AAF x Exposure
Frequency (day/ 365 day) x Exposure duration (year/years exposed)/
Body weight (kg)
Constituent concentrations in Fire Pond sediment, presented in Table 2-7, are used in this
assessment. Root uptake factors used in this evaluation are presented in Table 6-7. Muskrats
may consume up to one-third their body weight in food on a daily basis. This evaluation assumes
a body weight of 1.4 kg and a food consumption rate of 0.47 kg per day (1.4 kg + 3). It is
conservatively assumed that the muskrat's diet consists solely of aquatic plants from Fire Pond
and that the muskrat eats these plants at its maximum consumption rate on a daily basis for three
years. Thus, it is likely that the potential effects estimated in the muskrat evaluation will be an
overestimate.
Sediment Ingestion
Muskrats may inadvertently ingest sediment while ingesting aquatic plants and roots and when
building or repairing their lodge in the pond. The following equation is used to estimate potential
exposure to constituents via inadvertent sediment ingestion:
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Lifetime ·Average Daily Dose (mg/kg-day) = Constituent concentration in sediment (mg/kg
sediment) x Sediment ingestion rate (kg sediment/day) x Oral AAF x
Exposure frequency (day/365 days) x Exposure duration (years/years
exposed) / Body weight (kg)
Constituent concentrations in Fire Pond sediment, presented in Table 2-7, are used in this
assessment. No information on sediment ingestion was located for the muskrat. An ingestion
rate was calculated from the assumption that a certain percentage of the total intake of food (on
a dry matter basis) is composed of sediment. This is a practice commonly used for estimating
the soil ingestion rate of large foraging mammals such as sheep, cattle and deer. In this
evaluation, it is assumed that aquatic plants contain a similar amount of moisture as grasses.
On the average, grasses contain approximately 90 percent moisture (Emsinger, 1978). An
inadvertent sediment ingestion rate of three percent of the daily dry weight plant intake is used
in this evaluation. This corresponds to a sediment ingestion rate of approximately 1.41 grams
of sediment per day. Sediment ingestion from Fire Pond is assumed to occur every day for three
years.
6.5.2.2 Belted Kingfisher Exposure Evaluation
The belted kingfisher is assumed to reside in the vicinity of the Morrisville Site throughout its
entire three-year lifespan. The belted kingfisher primarily nests in nearly vertical earth exposures,
such as road cuts, cliffs, gravel pits and sand banks (Cramp et al., 1985). Because the banks
of Fire Pond and Medlin Pond are not appropriate for nesting, the kingfisher is assumed to nest
elsewhere. The foraging range of the belted kingfisher is approximately 8 kilometers (Cramp et
al., 1985). Because the foraging range of the belted kingfisher is relatively large (Cramp et al.,
1985), and because several bodies of water are present in the Morrisville Site area, the belted
kingfisher is conservatively assumed to obtain half of its daily food requirement from Fire Pond
throughout it's 3-year lifespan. Exposure is evaluated at Fire Pond rather than Medlin Pond
because the measured constituent concentrations are greater in Fire Pond than in Medlin Pond.
Thus, the belted kingfisher is assumed to be potentially exposed to constituents in Fire Pond
through fish ingestion. Calculation of the potential exposure through the fish ingestion exposure
pathway is described in detail below.
Pumpkinseed data from Fire Pond were used in the evaluation of potential exposure of kingfisher
to fish in the study area. Largemouth bass data were available for Medlin Pond, but were not
used here. The use of the body burdens found in largemouth bass might be expected to result
in higher exposures for the belted kingfisher than consumption of fish at lower trophic levels.
Examination of Table 2-1 indicates that three largemouth bass fillet composite samples were
collected from Medlin Pond. These were not used in the belted kingfisher analysis because the
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concentrations in fish fillets from Fire Pond were higher, and it was conservatively assumed that
the belted kingfisher was obtaining its food from Fire Pond. The mean concentration of TC DD-TE
from Medlin Pond was 1.19E-03 ug/L while the mean concentration from Fire Pond was 1.81 E-02
ug/L. The use of actual fish concentration data from Fire Pond from pumpkinseed provides a
more conservative estimat_e of exposure than the use of largemouth bass data from Medlin Pond.
Fish Ingestion
The diet of the kingfisher primarily consists of freshwater and marine fish, aquatic insects, and
occasionally, terrestrial insects and amphibians (Cramp et al., 1985). The following equation is
used to estimate potential constituent exposure from fish ingestion:
Average Daily Dose (mg/day) = Constituent concentration in fish (mg/kg fish) x
Fish ingestion rate (kg fish/day) x Exposure frequency (days/365 days)
x Exposure Duration (years/years exposed)
Fish were sampled from Fire Pond and actual constituent concentrations in fish fillets were
determined. These site-specific data are presented in Table 2-10 and are the constituent
concentrations used in this evaluation. The ingestion rate for the belted kingfisher was not
located in the literature. An ingestion rate for this species was calculated from a regression
equation developed by Nilsson and Nilsson (1976). These authors reported a correlation between
body weight and food consumption in fish-eating birds. A fish consumption rate of 36 grams/day
was calculated from the following equation:
Log F = -0.293 + 0.850 x Log W
Where,
F = Daily food consumption in grams, and
W = Body weight in grams.
The average body weight of the belted kingfisher is 150 grams (Cramp et al., 1985). The
kingfisher is assumed to ingest its entire daily fish requirement of 36 grams per day from Fire
Pond for 182 days of each year of its 3-year lifespan.
As in other animal species, dioxin is potentially expected to bioconcentrate in the tissue of the
kingfisher. Van den Berg et al. (1987) reported a 2,3,7,8-TCDD bioconcentration factor of 12 in
the bird. ENSR (1989) calculated a biological half-life of 7.22 days for 2,3,7,8-TCDD in the
bluebird. These parameters are used to obtain estimates of TCDD-TE body burden in the
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kingfisher at"the end of its 3-year lifespan (1095 days). The following equations are used to
calculate the TCDD-TE body burden in the bird:
TCDD-TE In Kingfisher On Day 1095 (mg/kg)= TCDD-TE average daily dose (mg/day) x
TCDD-TE BCF (kg food/kg tissue) x TCDD-TE
build-up (unitless) / Total daily food consumption (kg food/day)
Where,
TCDD-TE build-up= 1 -e·'"211 "'""
1
"'"'''
This equation utilizes first order kinetics to account for TCDD-TE build-up and elimination in the
bird over the 1095-day lifespan.
In this evaluation, the kingfisher is conservatively assumed to obtain half of its diet from Fire Pond
fish throughout its lifetime and will thus, theoretically, have no time to eliminate TCDD-TE from
the body. Therefore, depuration of TC DD-TE body burdens is not expected to occur and is thus
not considered in this evaluation.
6.5.3 Characterization of Potential Riparian Impacts
The potential chronic assumed adverse noncarcinogenic effects are estimated for terrestrial
species in a manner similar to that of the human health hazard indices. A "species-specific dose-
response value" is derived to represent the level of constituent exposure which will have no
adverse effects on a terrestrial receptor. The "estimated potential exposure" for the receptor is
then divided by the species-specific dose-response value to derive a "noncarcinogenic quotient".
Noncarcinogsnic Quotient-Estimated Potential Exposura
Species-Specific Doss-Response Vs/us
· The potential noncarcinogenic quotients can be summed for different constituents and different
pathways to calculate total potential noncarcinogenic quotient for the total estimated exposure of
an indicator species to constituent concentrations at the Site. The total noncarcinogenic quotient
is interpreted using the same criteria as those established by the EPA (1988b) for the toxicity
quotient method. Conclusions are expressed as "no concern" if the total noncarcinogenic quotient
is less than 0.1; "possible concern" if the quotient falls within the range of 0.1 and 1 O; and "high
concern" if the quotient is greater than 10. The total potential noncarcinogenic quotients
estimated for the muskrat and the belted kingfisher are discussed in the following subsections.
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6.5.3.1 Muskrat Characterization
Exposure to constituents by muskrats inhabiting Fire Pond results in an estimated total potential
noncarcinogenic quotient of 0.11. This quotient, which falls at the extreme lower end of the 0.1
and 10 range, and indicates "possible concern". Approximately 87 percent of the total
noncarcinogenic quotient is attributed to the muskrat's potential exposure to PCDD/PCDF in Fire
Pond sediment through ingestion of aquatic plants and sediments.
6.5.3.2 Belted Kingfisher Characterization
The potential noncarcinogenic quotient calculated for the kingfisher eating fish from Fire Pond and
assumed to be bioconcentrating PCDD/PCDF for 1095 consecutive days (daily throughout its
entire 3-year lifespan) is 0.30.
The data gathered for this evaluation were fish fillet concentrations from Fire Pond and Medlin
Pond. It may be more appropriate to evaluate the potential effects on the kingfisher of "whole
body" rather the fillet concentrations. The Integrated Risk Assessment for Dioxins and Furans
from Chlorine Bleaching in Pulp and Paper Mills (U.S. EPA, 1990c) indicates that a factor of two
can be used to adjust from fillet to whole body concentrations of 2,3,7,8-TCDD. This would result
in a potential noncarcinogenic quotient for Fire Pond, based on whole body fish concentrations,
of 0.60 which falls at the lower end of the 0.1 to 10 range and indicates "possible concern".
A corresponding potential noncarcinogenic quotient can be calculated for Medlin Pond based on
the comparison of fish tissue levels from Fire Pond (1.81 E-02 µg/L) and Medlin Pond
(1.19E-03 µg/L). The whole body fish concentration based noncarcinogenic quotient is directly
proportional to the fish concentration, so the resulting quotient for Medlin Pond would be 0.04.
This quotient falls below 0.1 and indicates "no concern".
6.6 Ecological Evaluation Summary
The results of this evaluation show that for the aquatic assessment, the acute toxicity quotients
for Fire Pond indicate "no concern" as defined by EPA. The chronic toxicity quotients for all
constituents except dioxin indicate "no concern", and the chronic quotient for dioxin in Fire Pond
indicates "high concern" as defined by EPA. This indicates that there is a potential for effects on
aquatic organisms from exposures to surface water in Fire Pond. For the aquatic assessment
in Medlin Pond, the calculated acute toxicity quotients were of "no concern" as defined by EPA,
and the calculated chronic toxicity quotients for several constituents were at the low end of the
range of "possible concern" and all others were of "no concern".
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The results cit the riparian evaluation show that for muskrats inhabiting Fire Pond, the calculated
quotient was at the lower end of the range indicating "possible concern". For belted kingfisher
inhabiting the Site area, the calculated quotient was also at the lower end of the range indicating
"possible concern".
The majority of potential assumed risk to ecological receptors estimated in this assessment is
attributable to dioxin in surface water. Dioxin was detected in three surface water bodies at this
Site, Fire Pond, Medlin Pond, and Western Ditch. Because both Fire Pond and Medlin Pond can
sustain aquatic and/or riparian life, the exposure of ecological receptors to these water bodies
was evaluated in this assessment. As shown, the potential exposure of aquatic receptors to Fire
Pond surface water may pose a risk of "high concern", and the potential exposure of aquatic
receptors to Medlin Pond surface water may pose a risk of "possible concern". The results of the
assessment also show that the assumed exposure of riparian receptors to the Ponds studied is
unlikely to result in adverse effects.
The majority of potential risk to ecological receptors from assumed exposure to the surface water
in Fire Pond and Medlin Pond is attributable to dioxin. Although dioxin was also detected in the
Western Ditch, dioxin in this Ditch is assumed not to pose an unexceptable potential ecological
risk for at least the following three reasons. First, the Western Ditch is not a viable aquatic
habitat because it only contains water on an intermittent basis and does not support an aquatic
community that could provide food, and thus potential exposure to constituents for the aquatic
receptors evaluated in this assessment, on a regular basis. Similarly, if any potential riparian
exposures were to occur to the ecological receptors evaluated in this assessment, they would be
lower than those estimated for Fire Pond because the concentrations of dioxin in the Western
Ditch are lower than those in Fire Pond. Because the risks associated with assumed riparian
exposures to Fire Pond estimated in this assessment were of no concern, any assumed exposure
to the Western Ditch would also be of no concern. Finally, the receptors selected for evaluation
in this assessment were chosen specifically because they were assumed to represent the most
sensitive ecological receptors potentially exposed to Site-related constituents. Specifically, these
receptors are potentially exposed to biomagnified levels of constituents while other receptors
would be potentially exposed to constituents primarily through direct contact with constituents in
environmental media. Thus, even if different receptors were exposed to the Western Ditch, the
potential ecological risks to these potential receptors are assumed to be less than assumed for
the receptors used in this ecological evaluation.
In addition to the surface water, the pond sediments pose a potential concern for ecological
impacts based on their potential to serve as a source of constituents to the surface water.
Actions, such as burial, which would render the constituents in the sediment biologically
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unavailable a:nd prohibit contact with surface water would greatly reduce any potential ecological
risks associated with constituents in the sediment.
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conservative ·approach that substantially overestimates the "average" level of potential risk posed
by a site.
The risk assessment approach used here employed upper 95% bounds or maximums for most
exposure and toxicity assumptions. Thus it produces estimates of potential risk two to three
orders of magnitude greater than the risk experienced by the average member of the potentially
exposed populations.
7.1.5 Summary of Sources of Uncertainty in the Human Health Evaluation
The large number of assumptions made in the risk characterization could potentially introduce a
great deal of uncertainty. While this could potentially lead to underestimates of potential risk, th.e
use of numerous upper-bound assumptions guarantees that overestimates of potential risks will
result. As discussed elsewhere in the report, any one person's potential exposure and
subsequent assumed risk are influenced by all the parameters mentioned in the text and will vary
on a case-by-case basis. Despite inevitable uncertainties associated with the steps used to
derive potential risks, the use of numerous health-protective assumptions will most likely lead to
an overestimate of potential risks from the Site.
7.2 Uncertainties Associated with the Ecological Evaluation
A large number of assumptions that can lead to uncertainty are made in the evaluation of the
potential for assumed adverse ecological effects at the Morrisville Site. Given the conservative
assumptions set forth in the guidance documents, the results of this evaluation may overestimate
the potential for adverse ecological effects at this Site. A qualitative discussion of the major
sources of uncertainty associated with the ecological evaluation is presented below.
Extrapolation of the potential for community, population, or ecosystem effects from the
examination of one or more indicator species is a major source of uncertainty for both the aquatic
and terrestrial analyses. The underlying assumption is that potential effects on one species are
representative of effects on the particular ecosystem being investigated. For this assessment,
bluegills were chosen to represent potential effects on aquatic ecosystems, muskrats were chosen
to represent potential effects on mammalian organisms in terrestrial ecosystems, and belted
kingfishers were chosen to represent potential effects on avian species in terrestrial ecosystems.
Each of these choices represents a potential source of uncertainty. It is difficult to predict how
an adverse effect on an individual organism would affect the ecosystem as a whole. U.S. EPA
( 1989a) states that "concentrations that are acutely toxic to single species are usually not much
greater than concentrations that are toxic at the ecosystem level. Whereas, concentrations that
are toxic in chronic single species are, in most cases, overprotective of ecosystems." This
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8.2 Ecological Evaluation Summary
The ecological evaluation assessed aquatic and terrestrial (mammalian and avian) receptors,
focusing on three indicator species: bluegills, muskrat, and belted kingfisher. The potential for
adverse effects to these species was quantitatively evaluated by the quotient method (U.S. EPA,
1988b; ORNL, 1986). The calculated quotient is classified by EPA as being of "no concern" if
less than 0.1, of "possible concern" if between 0.1 and 10, and of "high concern" if greater than
1 O (U.S. EPA, 1988b). For bluegills in both Fire Pond and Medlin Pond, the calculated acute
toxicity quotients indicate "no concern". For Fire Pond, the calculated chronic toxicity quotient for
all constituents except dioxin, indicates "no concern". The chronic toxicity quotient for dioxin in
Fire Pond indicates "high concern" as defined by EPA. This indicates that there is a potential for
effects on aquatic organisms from exposures to surface water in Fire Pond, which indicates that
remediation of surface water in Fire Pond may be appropriate. For bluegills in Medlin Pond,
calculated chronic toxicity quotients for several constituents were at the very low end of the range
of "possible concern" and all others were "no concern". These quotients were also calculated
using EPA-prescribed screening values. Due to the uncertainty associated with the screening
values used to evaluate the potential for adverse effects from exposure to surface water, it may
also be appropriate to remediate surface water in Medlin Pond.
For muskrats inhabiting Fire Pond, the calculated quotient was at the extreme lower end of the
range indicating "possible concern". For belted kingfisher inhabiting the Site area, the calculated
quotient was also at the lower end of the range indicating "possible concern". The majority of risk
for ecological receptors in associated with potential exposure to surface water in Fire Pond. As
discussed in Section 6, if the belted Kingfisher was assumed to eat fish from Medlin Pond instead
of Fire Pond, the noncarcinogenic quotient would be 0.04, which indicates "no concern".
8.3 Baseline Risk Assessment Summary
Thus, the results of the baseline risk assessment indicate that remediation is likely required for
only surface soil in Area C, surface water in Fire Pond, surface water in Medlin Pond and on-Site
ground water under the Eastern and Former Lagoon Areas, and that remediation is likely not
necessary for other areas and environmental media. Section 9.0 presents a comparison of risk-
based target clean-up levels with Federal and State ARARs and other relevant guidelines. As
described in Section 9.0, additional areas may require remediation based on factors other than
estimated assumed risks to human or ecological receptors.
r:\pubs\proiacts\084 5008\51 O. ss 8-2 July. 1992
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Hypothetical ·receptors were evaluated for each of the two potential future Site use conditions
evaluated in the baseline risk assessment. On-Site Workers and Local Off-Site Residents were
evaluated for the commercial/industrial Site use scenario. The Local Off-Site Resident evaluation
includes the potential exposures of teenagers trespassing on the Site. At the request of EPA,
hypothetical On-Site Resident receptors were evaluated for potential future residential use of the
Site. Appendix G presents the RBTCLs derived for pentachlorophenol and PCDD/PCDF for each
of these receptors.
9.1.2 Ecological Evaluation
The ecological evaluation presented in Section 6.0 and Appendix G of the baseline risk
assessment showed that potential assumed risks to ecological receptors for all constituents,
except PCDD/PCDF in Fire Pond surface water, were at the level of "no concern" as defined by
EPA. This indicates no need for remediation of surface water in Fire Pond or Medlin Pond for
these constituents. The assumed potential exposure of aquatic species to PCDD/PCDF in Fire
Pond surface water was evaluated in the baseline risk assessment using a screening toxicity
value required by EPA. The results of this evaluation indicate that potential aquatic exposures
to PCDD/PCDF in Fire Pond are of "high concern" as defined by EPA. This indicates that there
is a potential for effects on aquatic organisms from exposures to surface water in Fire Pond,
which indicates that remediation of surface water in Fire Pond may be appropriate. Due to the
uncertainty associated with the screening values used to evaluate the potential for adverse effects
from exposure to surface water, it may also be appropriate to remediate surface water in Medlin
Pond to protect aquatic organisms.
Specific methodologies exist for determining RBTCLs for potential human exposures based on
allowable risk levels. Similar specific guidance is not available for aquatic receptors.
9.2 Comparison of RBTCLs and ARARs
When remediation goals for media or areas of the Site are considered, the RBTCLs and all
applicable standards can be compared in order to determine the most reasonable and appropriate
remediation measures to pursue. The relevant ARARs identified for the constituents of interest
in this evaluation are North Carolina standards and federal MCLs for pentachlorophenol and
2,3,7,8-TCDD, and the North Carolina MCL for 2-chlorophenol. Soil target clean-up levels for the
protection of ground water have also been derived for these two constituents (Keystone, 1992).
This section presents a summary of the comparison of maximum measured constituent
concentrations, as directed by U.S. EPA Region IV in consideration of potential hot spot exposure
under future residential scenarios, in various media with RBTCLs derived for the hypothetical
R:\P UBS\PAOJE CTS\064 5008\51 0 .S9 9-3 Juty, 1992
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receptors, State of North Carolina and federal ARARs, and soil clean-up levels for the protection
of ground water. A detailed discussion of this comparison is presented in Appendix G.
Comparison to average constituent concentrations is also scientifically and statistically appropriate
for some exposure scenarios, but is not presented in this document at the request of U.S. EPA
Region IV.
Existing maximum concentrations of constituents, as directed by EPA, were compared with
RBTCLs, soil target clean-up levels for the protection of ground water, and State and federal
ARARs. The results of the ecological evaluation and the results of the human exposure analysis
indicate that existing maximum constituent concentrations exceeded RBTCLs (at the 1 E-05 risk
level), ARARs, or soil target clean-up levels for the protection of ground water, only in the
following media:
• Surface Soil in Area C
• Subsurface Soil in Area C
• Surface Water in Fire Pond
• Surface Water in Medlin Pond
• Fish in Fire Pond
• Ground Water in the Former Lagoon Area
• Ground Water in the Eastern Area
In Area C surface soil, existing maximum concentrations of pentachlorophenol exceeded RBTCLs
at the 1 E-06 risk level for local off-Site residents, and RBTCLs at the 1 E-05 risk level for on-Site
workers in the commercial/industrial Site use scenarios. In Area C surface soil, existing maximum
concentrations of PCDD/PCDF exceeded the RBTCLs at the 1 E-04 risk level for the local off-Site
resident and the on-Site worker in the commercial/industrial Site use scenarios. In Area B surface
soil, the maximum measured concentration of PCDD/PCDF exceeded the RBTCL at the 1 E-06
risk level for the on-Site worker in the commercial/industrial Site use scenarios.
In the residential Site use scenarios, the maximum concentration of pentachlorophenol in Area
C surface soil exceeded the RBTCL at the 1 E-04 risk level for the hypothetical on-Site resident.
The maximum concentrations of PCDD/PCDF in Area B and Area C surface soil were exceeded
by the RBTCLs at the 1 E-05 and 1 E-04 risk levels, respectively, for the hypothetical on-Site
resident.
In addition, existing maximum concentrations of pentachlorophenol and PCDD/PCDF exceeded
the soil target clean-up levels for the protection of ground water.
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In Area C subsurface soil, existing maximum pentachlorophenol concentrations exceeded the soil
target clean-up level for the protection of ground water. Maximum concentrations of PCDD/PCDF
in Area C subsurface soil exceeded the RBTCLs at the 1 E-06 risk level for the local off-Site
resident and the on-Site worker in the commercial/industrial Site use scenarios. Maximum
concentrations of pentachlorophenol and PCDD/PCDF in subsurface soil in Area C exceeded the
RBTCLs at the 1 E-06 risk level for the hypothetical on-Site resident in the future residential Site
use scenarios.
In the commercial/industrial Site use scenarios, the maximum concentration of PCDD/PCDF in
Fire Pond surface water exceeded the RBTCL for the local off-Site resideni at the 1 E-06 risk
level. In the future residential Site use scenarios, the maximum concentration of PCDD/PCDF
in Fire Pond exceeded the RBTCL for the hypothetical on-Site resident at the 1 E-04 risk level.
In the ecological evaluation, surface water in Fire Pond and surface water in Medlin Pond may
require remediation for the protection of aquatic species.
In sediment in the discharge stream from Fire Pond, maximum PCDD/PCDF concentrations
exceeded the RBTCL for the local off-Site resident at the 1 E-06 risk level. In Fire Pond, the
maximum sediment concentration exceeded the RBTCL for the hypothetical on-Site resident at
the 1 E-06 risk level.
In ground water in the Eastern Area, maximum pentachlorophenol concentrations exceeded
RBTCLs at the 1 E-05 risk level. In Former Lagoon Area ground water, maximum
pentachlorophenol concentrations exceeded RBTCLs at the 1 E-04 risk level. Maximum
pentachlorophenol concentrations in both areas exceeded the MCL for pentachlorophenol. In
ground water in the Fonmer Lagoon Area and Eastern Area, maximum concentrations of
PCDD/PCDF exceeded RBTCLs at the 1 E-04 risk level and also exceeded the proposed MCL
for PCDD/PCDF.
In Eastern Area ground water, the maximum concentration of 2-chlorophenol exceeded the State
of North Carolina MCL for this constituent. In Off-Site Area ground water, one estimated sample
(designated by the "J" qualifier in the laboratory results) exceeded the State MCL for 2-
chlorophenol. RBTCLs for 2-chlorophenol in ground water were not calculated here because the
focus of this report is on the two constituents contributing nearly 100 percent of the assumed risk,
pentachlorophenol and dioxin. Because the maximum detected concentrations of 2-chlorophenol
in Eastern Area ground water exceeded the State ARAR for this constituent, remediation may be
required in this area. Because the only detected value for 2-chlorophenol in Off-Site Area
groundwater is an "estimated" value, and because the sampling location in which this value was
estimated is located within the bounds of the area that will be impacted by pumping of Site
A :\P UBS\PROJE CTS\0845008\51 0. S9 9-5 July, 1992
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ground water: Off-Site Area groundwater is not identified as an area that may require remediation.
Any remediation of the on-site plume of constituents will also address any constituents in off-Site
Area ground water. Additional sampling of off-site wells will be conducted during the remedial
phase to confirm the recommendation that off-site Area ground water does not require a separate
remediation effort.
Maximum concentrations of PCDD/PCDF in fish tissue from Fire Pond exceeded RBTCLs at the
1 E-06 risk level for both the local off-Site resident and the hypothetical on-Site resident. In Medlin
Pond, maximum concentrations of PCDD/PCDF in fish tissue exceeded RBTCLs only at the 1 E-
06 risk level for the local off-Site resident.
9.3 Summary and Recommendations
This Section has reviewed the clean-up levels evaluation presented in Appendix G of the baseline
risk assessment. The human health RBTCLs were determined using the potential assumed
carcinogenic risks estimated in the baseline risk assessment, which was conducted following EPA
guidance and in accordance with standard risk assessment methodology. Parallel analyses for
ecological receptors suggest that remedial action may be necessary for surface water in Fire
Pond and in Medlin Pond.
Human health RBTCLs were derived for potential future receptors assuming two different potential
future Site use conditions. At this time, no decision has been made regarding the future use of
the Site. However, it is unlikely that the Site will become residential in the future because recent
development in the area has been commercial/industrial, and the Site is currently occupied with
industrial enterprises. In addition, institutional controls, such as placing a land-use restriction on
the deed for the property preventing residential use, can and will be introduced by Beazer to
assure that its portion of the Site remains commercial/industrial.
As described in Section 9.2 and in Appendix G, on-Site surface and subsurface soil in Area C,
surface water in Fire Pond, surface water in Medlin Pond, fish in Fire Pond, and on-Site ground
water in the Former Lagoon, and Eastern Areas may require remediation. Table 9-1 presents a
summary of the areas with the corresponding existing maximum constituent concentrations,
RBTCLs, ARARs and soil target clean-up levels for protection of ground water evaluated in detail
in Appendix G.
Table 9-1 also shows the clean-up goals recommended by Beazer East, Inc. for the various
media identified here. For surface and subsurface soil in Area C, the recommended clean-up
goals are the soil target clean-up levels for the protection of ground water. For Fire Pond surface
water and fish, the recommended clean-up goals are the human health RBTCLs at the 1 E-05 risk
A:\P U BS\PROJE CTS\0845008\51 O.S9 9-6 July, 1992
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level derived in Appendix G. For ground water, the recommended clean-up goals are the federal
or state ARARs, or MCLs.
The recommended soil clean-up goals at this Site are the soil target clean-up levels for the
protection of ground water: 95 ppm for pentachlorophenol, and 0.007 ppm for PCDD/PCDF.
Upon review of the available surface soil data in Area C, it is apparent that remediation of
pentachlorophenol to it's clean-up goal for the protection of ground water will also achieve the
clean-up goal for PCDD/PCDF. This is illustrated in Table 9-2. The measured pentachlorophenol
concentrations in Area C surface soil are ranked in descending order and are compared with the
pentachlorophenol soil target clean-up level for the protection of ground water. Four samples in
this area exceed the soil target clean-up level for the protection of ground water. Based upon the
historical operations of the Koppers facility on the Site, it is likely that the occurrence and
concentration of pentachlorophenol and PCDD/PCDF in surface soils are co-located. This co-
location of constituents is shown on Table 9-2. Therefore, when these four areas are remediated,
the samples with concentrations in excess of the PCDD/PCDF soil target clean-up level for the
protection of ground water are also remediated. This remediation strategy will be investigated
further in the pre-design activities for the Remedial Design Scope of Work.
As a result of this analysis, it is apparent that treating the remediation of pentachlorophenol and
PCDD/PCDF separately is unnecessary. Focussing the remediation strategy on remediating soils
in Area C such that 95 ppm is not exceeded for pentachlorophenol, will also result in achievement
of the soil target clean-up level for the protection of ground water for PCDD/PCDF. This proposed
remediation strategy will be confirmed during the remedial design study at this Site.
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REFERENCES (Continued)
U.S. EPA. 1990b. Drinking Water Regulations and Health Advisories. Office of Drinking Water.
U.S. EPA, November 1990.
U.S. EPA. 1990c. Integrated Risk Assessment for Dioxins and Furans from Chlorine Bleaching
in Pulp and Paper Mills. Office of Pesticides and Toxic Substances, Washington, D.C.
EPA/560/5-90-011.
U.S. EPA. 1991 a. Integrated Risk Information System (IRIS). Environmental Criteria and
Assessment Office, Cincinnati, OH.
U.S. EPA. 1991 b. Supplemental Region IV Risk Assessment Guidance. U.S. EPA, Region IV,
Atlanta, GA.
U.S. EPA. 1991 c. 304(a) Screening Values and Related Information for Toxic Pollutants.
Screening List. Water Management Division, Office of Water Quality Standards. U.S. EPA
Region IV. Atlanta, GA.
U.S. EPA. 1992. Region IV Waste Management Division Screening Values for Hazardous
Waste Sites. Version Dated 1/27/92.
Van den Berg, M., F. Blank, C. Heeremans, H. Wagenaar and K. Olie. 1987. Presence of
Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fish-catching birds
and fish from the Netherlands. Arch. Environ. Contam. Toxicol. 16:149-158.
Versar, Inc., 1979. Water-Related Environmental Fate of 129 Priority Pollutants. Vol. 1 and 2,
U.S. Environmental Protection Agency, Washington, D.C., EPA 440/4-79-029.
Verschueren, K. 1977. Handbook of environmental data on organic chemicals. Van
Nostrand/Reinhold Co., New York. p. 659.
Wipf, H., E. Hornberger, N. Neuner, U. Ranalder, W. Vetter, and J. Vuilleumier. 1982. TCDD
Levels in Soil and Plant Samples from the Seveso Area. (As cited in Hutzinger et al. 1982).
A:\P U 8S\P ROJ E CTS\0845008\51 0. A E F July, 1992
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mg/kg. The-RBTCLs for pentachlorophenol are less than this concentration. If chronic RBTCLs
had been higher, it would need to have been limited at the concentration protective of assumed
potential sub-chronic effects.
As discussed in Appendix E, at the reques\ of U.S. EPA Region IV, the calculations used to
estimate potential assumed risks that included degradation factors were edited to remove these
factors from the main text of the final report because no site-specific data confirming the
degradation of constituents in various media is available. The main text of this report shows only
the results from the evaluation that assumes no degradation will occur. These results are also
discussed in this Appendix. Because there is evidence in the literature that supports the
degradation of pentachlorophenol and dioxin, soil and sediment calculations including the
assumption of degradation are also included in this Appendix. As described above, two sets of
degradation rates were used in the derivation of RBTCLs for pentachlorophenol, 60 days (as was
used in the first drafts of the report and is summarized in Appendix E), and 1 year (based on a
more detailed literature search on the degradation of pentachlorophenol). U.S. EPA Region IV
has not approved of the application of any degradation rates found in the literature, yet if
literature-derived degradation rates are to be used, Region IV has reported a preference for the
1 year half-life for pentachlorophenol in surface soils, and not 60 days as was first used in this
baseline risk assessment. If the half-life for pentachlorophenol is assumed to be 1 year, the
potential assumed risks estimated in Appendix E would have been slightly higher than those
presented (which are based on a half-life of 60 days). Therefore, three sets of RBTCLs were
derived for pentachlorophenol for each relevant receptor, RBTCLs derived assuming no
degradation occurs, RBTCLs using degradation rates used in the first drafts of the baseline risk
assessment, and RBTCLs using alternate degradation rates taken from the literature and
summarized here. Two sets of RBTCLs were derived for dioxin for each relevant receptor,
RBTCLs derived assuming no degradation occurs, and RBTCLs using degradation rates used in
the first drafts of the baseline risk assessment. The recommendations for potential remediation
at the Site (see Section G.5) were based on RBTCLs assuming degradation does not occur, as
requested by EPA.
Constituent concentrations in surface water, ground water and fish were not adjusted for
degradation in the baseline risk assessment, nor in this clean-up levels evaluation, because
constituent concentrations need to meet existing standards in surface water and ground water,
and no information was available in the scientific literature to thoroughly evaluate degradation of
the constituents of interest in fish.
A :\PU 85\PAOJ E CTSID84 5008\51 0.A PG G-7 July, 1992
G.1.2: Application of RBTCLs
The potential assumed risks estimated by the baseline risk assessment report are based upon
long-term or chronic exposures. Two different kinds of long term exposure could occur: those
that involve a random pattern of contact with the exposure medium, and those that involve a non-
random pattern of contact with the exposure medium. Because constituent concentrations vary
across environmental media, the type of potential contact (i.e. random or non-random) will affect
the average constituent concentration to which a receptor would be exposed over the long term .
. For example, in surface soil, measured concentrations of some of the constituents of interest ai
this Site range from samples in which the constituent was not detected, to samples in which the
constituent was detected at various concentrations. Certain exposure scenarios assume that the
receptor is equally likely to contact each of these concentrations over the exposure period, this
kind of potential exposure is assumed to be "random". Examples of this type of potential
exposure are the trespasser receptor and the on-Site worker receptor. Each of these receptors
is assumed to contact constituents in surface soil across the Site over a long period of time.
The repeated random potential contact with constituent concentrations over the exposure period
assumed by certain scenarios in the risk assessment effectively averages the constituent
concentration a hypothetical person is exposed to over that period. Thus, over the duration of
hypothetical exposure, a person will be exposed to the average constituent concentration, rather
than the maximum or some upper or lower bound concentration. Indeed, as the variance in
constituent concentrations increases, the probability of a person being exposed to an upper bound
constituent concentration becomes vanishing small. This situation is illustrated by Figure G-2
which was developed to illustrate the central limit theorem. The basic principle of this theorem
is that regardless of how skewed the original distribution is (the top of Figure G-2), the distribution
of the means of several sets of samples will be closer to a normal distribution with a most
frequent result approaching the arithmetic average of the original distribution (center of Figure G-
2). When the number of samples in a set is very large, the distribution of means becomes
normally distributed, or centered around the arithmetic average (bottom of Figure G-2). This
phenomenon should be accounted for when applying RBTCLs to determine site remediation
requirements. In particular, because of this phenomenon, it is the average concentration of a
constituent in an area of the site that needs to be equal to the RBTCL or other clean-up goals
based on potential assumed long term random exposures.
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risk, recommendations for remediation may be made based on ARARs or other factors such as
soil clean-up levels for the protection of ground water. In addition, the NCP seeks to require
protection of ground water to allow for its maximum beneficial use. Thus, although constituent
concentrations may not exceed RBTCLs, remediation of ground water to MCLs (i.e. to levels
suitable for residential drinking water purposes) may be required.
No constituent concentrations in Western Area ground water exceed RBTCLs, indicating that
remediation of ground water in this area would not be necessary based on RBTCLs.
G.2.3.6 Fish Sample Results
Pentachlorophenol was not detected in fish tissue samples in any pond of interest. For fish fillet
samples from Fire Pond, the maximum concentrations of PCDD/PCDFs are below the RBTCL at
the 1 E-4 risk level. For fish fillet samples from Fire Pond, the maximum concentrations of
PCDD/PCDF exceed the RBTCLs at the 1 E-5 and 1 E-6 risk levels, indicating that, if the Site were
to become residential, which is considered unlikely, a remedial measure restricting use of fish
from Fire Pond may be needed.
G.3 Ecological RBTCLs
The previous sections have described the derivation of human health based RBTCLs. This
section presents the procedure to derive ecologically based RBTCLs. Section G.3.1 summarizes
the methodology and results of the ecological risk assessment for the Site. Justification for not
deriving ecological RBTCLs is presented in Section G.3.2.
G.3.1 Review of the Ecological Risk Assessment
The ecological risk assessment was conducted following EPA guidance documents: Risk
Assessment Guidance for Superfund: Volume II. Environmental Evaluation Manual (U.S. EPA,
1989d), Recommendations for and Documentation of Biological Values for Use in Risk
Assessment (U.S. EPA, 1988a); Quality Criteria for Water, 1986 (U.S. EPA, 1986); Review of
Ecological Risk Assessment Methods (U.S. _EPA, 1988b); and Ecological Assessment at
Hazardous Waste Sites (U.S. EPA, 1989a).
The ecological evaluation includes a habitat characterization, a review of indicator species, a
qualitative evaluation of terrestrial species, and a quantitative evaluation of both aquatic and
riparian species. The methods used to derive potential assumed hazard quotients for aquatic and
riparian species are described below.
R:\P UBS\PAOJ E CTS\08-4 5008\51 O.A PG G-17 July, 1992
. G.3.1.1 Aquatic Evaluation
The evaluation of potential assumed exposure of aquatic species to constituents was performed using the toxicity quotient method prescribed by EPA (U.S. EPA, 1988b, ORNL, 1986). This method involves the derivation of a toxicity quotient which is the result of a comparison of surface water constituent concentrations with "benchmark concentrations" for potential assumed toxicological effects. Therefore, all constituents of interest evaluated in the risk assessment are reported here. Acute and chronic noncarcinogenic benchmark concentrations were used to evaluate both potential assumed acute and potential assumed chronic exposures. The benchmark concentrations used in the risk assessment are "screening" values provided by EPA Region IV. Toxicity quotients are classified by EPA as being of "no concern" if less than 0.1, of "possible concern" if between 0.1 and 10, and of "high concern" if greater than 10 (U.S. EPA, 1988b).
The acute toxicity quotients for each of the constituents in Fire Pond and Medlin Pond were all less than 0.01 (Table G-6), and fall in the range of "no concern" (U.S. EPA, 1988b). The results of the chronic hazard screening evaluation for Fire Pond (Table G-7) indicate that TCDD may pose "high concern" (toxicity quotient= 17) for aquatic species according to the EPA classification criteria (U.S. EPA, 1988b). The results of the chronic hazard screening evaluation for Medlin Pond (Table G-7) indicate that TCDD, 2,4,6-trichlorophenol, 2,4-dinitrophenol, 2,3,5,6-tetrachlorophenol, and 2-methyl-4,6-dinitrophenol may pose "possible concern" for aquatic species. Note that each of the constituents in Medlin Pond that fall within EPA's range of "possible concern" are at the extreme low end of this range except for TCDD-TE. This indicates that surface water in Fire Pond and surface water in Medlin Pond may require remediation to protect aquatic organisms.
G.3.1.2 Riparian Evaluation
The evaluation of riparian species at the Site follows a method similar to that used to estimate potential assumed risks to human health. This method involves the application of dose-response criteria and a series of exposure assumptions to a constituent concentration to derive a hazard quotient for a given receptor. The ecological receptors evaluated in the risk assessment are muskrat and belted kingfisher. The muskrat and belted kingfisher were assumed to potentially be exposed to constituents detected in Fire Pond.
The hazard quotient is calculated using the following equation:
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Hazard Quotient= Estimated Assumed PotBntial Exposu"' DoSB-ResponSBValUB
where: the "estimated potential assumed exposure" is derived from a series of assumptions about
the potential assumed exposure of the receptor to constituents in Fire Pond; and the "dose-
response value" is a species-specific value.
The evaluation indicates that the muskrat's total potential assumed hazard quotient is 0.1. This
is at the very bottom of the EPA's range of "possible concern" (0.1 to 10.0), and represents the
sum of all constituent-specific, potential assumed hazard quotients for the muskrat. The results
of the kingfisher evaluation show that the potential assumed exposure of the kingfisher to TCDD-
TEs leads to an potential assumed hazard quotient of 0.6. This is also at the low end of the
"possible concern" range (0.1 -10.0).
G.3.2 Ecological RBTCLs
The method described in Section G.1 of this evaluation for deriving human health RBTCLs could
also be used to derive ecological RBTCLs; however, because no specific methodologies exist for
determining clean-up levels for ecological receptors, no ecological RBTCLs were derived.
In addition, although surface water in Fire Pond and Medlin Pond were identified as areas that
may require remediation based on the results of the aquatic evaluation of TCDD-TE in surface
water, the aquatic screening values are not intended for use in the derivation of clean-up levels
(U.S. EPA, 1992). Thus, no ecological RBTCLs are derived from the results of the aquatic
evaluation presented in the risk assessment. However, a further comparison with other,
scientifically defensible, benchmark concentrations was made based .on the results of the
comparison with Region IV screening values. Chronic benchmark values were derived for 2,4,6-
trichlorophenol, 2,4-dinitrophenol, 2,3,5,6-tetrachlorophenol, 2-methyl-4,6-dinitrophenol, and
2,3,7,8-TCDD for constituents in Medlin Pond and for 2,3,7,8-TCDD in Fire Pond. The derivation
of these benchmarks, and the resulting chronic toxicity quotients, is described below.
2,4,6-Trichlorophenol
The Ambient Water Quality Criteria for Chlorinated Phenols (U.S.EPA, 1980a) indicates that the
only freshwater chronic data found were for 2,4,6-trichlorophenol. The species mean acute value
for an early life cycle stage test with fathead minnow was 720 µg/1. EPA Region IV recommends
the application of a safety factor of ten when the data concerning the acute toxicity of a
A :\PU BS\P ROJ E CT SIDS4 5008\5 1 0. A PG G-19 Juty, 1992
compound are limited. Applying this safety factor to limited chronic toxicity data would result in a chronic effects benchmark concentration of 72 µg/1 for Medlin Pond and a chronic toxicity quotient of 0.008. This quotient falls in the range of "no concern" as defined by EPA (U.S. EPA, 1988b), and thus, no clean-up levels will be calculated for 2,4,6-trichlorophenol.
2.4-Dinitrophenol
The Ambient Water Quality Criteria for Nitrophenols (U.S.EPA, 1980e) indicates that no freshwater chronic data were found for nitrophenols. The document indicates that toxicity to one species of algae may occur at concentrations as low as 150 µg/1. EPA Region IV recommends the application of a safety factor of ten when the data concerning the acute toxicity of a compound are limited. Applying this safety factor to limited chronic toxicity data would result in a chronic effects benchmark concentration of 15 µg/ for Medlin Pond and a chronic toxicity quotient of 0.05. This quotient falls in the range of "no concern" as defined by EPA (ref), and thus, no clean-up_ levels will be calculated for 2,4-dinitrophenol.
2 ,3 ,5 ,6-Tetrachlorophenol
The Ambient Water Quality Criteria for Chlorinated Phenols (U.S.EPA, 1980a) indicates that no freshwater chronic data found were for tetrachlorophenols. Three species mean acute values were presented. The species mean acute values for 2,3,5,6-tetrachlorophenol with Daphnia magna and bluegill (Lepomis macrochirus) were 570 µg/I and 170 µg/I, respectively. An additional acute value of 140 µg/I for the effects of 2,3,4,6-tetrachlorophenol with bluegill was reported. EPA Region IV recommends the application of a safety factor of ten when the data concerning the acute toxicity of a compound are limited and the application of an additional safety factor of ten when extrapolating from acute to chronic effects. This would result in a chronic effects benchmark concentration of 14 µg/1 for Medlin Pond based on 2,3,4,6-tetrachlorophenol
and a chronic toxicity quotient of 0.14. This quotient falls at the extreme low end of the range of "possible concern" as defined by EPA (1988b) and thus, no clean-up levels will be calculated for 2,3,5,6-tetrachlorophenol.
2-Methyl-416-dinitrophenol
The Ambient Water Quality Criteria for Nitrophenols (U.S.EPA, 1980e) indicates that no freshwater chronic data were found for nitrophenols. The document indicates that toxicity to one species of algae may occur at concentrations of 2-methyl-4,6-dinitrophenol as low as 150 µg/1. EPA Region IV recommends the application of a safety factor of ten when the data concerning the acute toxicity of a compound are limited. Applying this safety factor to limited chronic toxicity data would result in a chronic effects benchmark concentration of 15 µg/1 for Medlin Pond and a chronic toxicity quotient of 0.04. This quotient falls in the range of "no concern" as defined by EPA (1988b), and thus, no clean-up levels will be calculated for 2-methyl-4,6-dinitrophenol.
R:\P U8S1 PROJE CTS\OIM 5008\.S 1 O.A PG G-20 Jury. 1992
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2,3,7,8-TCDD
Two major sources examined for toxicity information on 2,3,7,8-TCDD. The Fish and Wildlife
service "conservatively estimated that water levels of 2,3,7,8-TCDD should not exceed 0.01 ng/I"
(Eisler, 1986). Some of the data upon which this "conservative estimate" is based comes from
24 hour exposures of guppies. A chronic value was also reported from a 96 hour test on
Northern pike embryos. The Ambient Water Quality Criteria for 2,3,7,8-TCDD (U.S. EPA, 1984)
indicates that insufficient freshwater chronic data were available to calculate a chronic criterion.
The EPA also reviewed the information used as the basis of the Fish and Wildlife Service report
including the 96 hour test on Northern pike embryos that indicated a "slight reduction in growth
up to 21 days." The criteria document concluded that "the available information indicates that
acute values for some freshwater animal species are greater than 1.0 µg/I; some chronic valu~s
are less than 0.1 µg/I, and the chronic value for rainbow trout is less than 0.001 µg/I" (U.S.EPA.
1984). EPA Region IV recommends the application of a safety factor of ten when the data
concerning the acute toxicity of a compound are limited. Applying this safety factor to the limited
chronic toxicity data reported for rainbow trout would result in a chronic effects benchmark
concentration of 0.0001 µg/I for Fire Pond and Medlin Pond and chronic toxicity quotients of 1.65
and 0.12, respectively. These quotients fall at the low end of the range of "possible concern" as
defined by EPA (U.S. EPA, 1988b). Specific methodologies exist for determining clean-up levels
for human health based on allowable risk levels. Similar specific guidance is not available for
aquatic receptors, thus, no RBTCLs are derived for aquatic receptors.
The muskrat evaluation indicated a total potential assumed hazard quotient equal to 0.1. Each
constituent-specific hazard quotient is less than 0.1, or of "no concern". Because the estimated
exposure to each constituent results in an potential assumed hazard quotient considered to be
of "no concern", no RBTCLs were calculated for the muskrat. Similarly, the potential assumed
hazard quotient for the kingfisher for TCDD-TE is 0.6 which is at the low end of the range of
"possible concern". Thus, no ecological RBTCLs were derived for the kingfisher. The results of
both of these evaluations indicate that remediation is not necessary to protect riparian ecological
receptors.
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G.4 Comparison of ARARs and RBTCLs
This section presents a comparison of existing constituent concentrations in various media with RBTCLs derived in Section G.2, State of North Carolina and federal ARARs, and soil target clean-up levels derived for the protection of ground water. When remediation goals for media or areas of the Site are considered, the RBTCLs and all applicable standards can be compared in order to detennine the most reasonable and appropriate remediation measures to pursue.
The relevant ARARs identified for the constituents of interest in this document are North Carolina standards and federal MCLs for pentachlorophenol and 2,3,7,8-TCDD, and the North Carolina MCL for 2-chlorophenol. Soil target clean-up levels for the protection of ground water have also been derived for pentachlorophenol and 2,3,7,8-TCDD (KER, 1992a).
Tables G-2, G-2a, G-3 and G-3a present a comparison of ARARs and RBTCLs derived for the commercial/industrial Site use scenarios for pentachlorophenol and PCDD/PCDF, respectively. Tables G-4, G-4a, G-5 and G-Sa present a comparison of ARARs and RBTCLs derived for the hypothetical future residential Site use scenarios for pentachlorophenol and PCDD/PCDF, respectively. The existing average, RME, and maximum constituent concentrations are presented here for comparison with RBTCLs and ARARs. As discussed in Section G-1, Beazer East, Inc. feels the comparison of RBTCLs and ARARs with average values is appropriate for setting remedial goals because of the many conservative assumptions used to derive the RBTCLs. However, at the request of EPA, comparison of RBTCLs and ARARs with maximum values is the focus of this evaluation. In addition, the model used to derive soil target clean-up levels for the protection of ground water requires comparison of resulting target levels with maximum constituent concentrations in soil.
Section G .4.1 describes the comparison of the derived RBTCLs for soil with the appropriate standards. Section G.4.2 describes the comparison of RBTCLs derived in this document for surface water with the appropriate standards. Section G.4.3 describes the comparison of RBTCLs derived in this document for sediment with the appropriate values. Section G.4.4 describes the comparison of RBTCLs derived in this document for ground water with the appropriate standards. Section G.4.5 reviews the findings of the fish analysis presented in Section G.2.
R:\PUBS\PROJECTS\0&45008\51 0.APG G-22 Jury, 1992
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G.4.1 . Comparison of Soil RBTCLs and ARARs
Soil target clean-up levels for the protection of ground water were derived for pentachlorophenol
and 2,3,7,8-TCDD in a separate report (KER, 1992a). Section G.4.1.1 reviews the results of the
comparison of concentrations of constituents with soil target clean-up levels for the protection of
ground water and RBTCL.s derived for soil in the commercial/industrial Site use scenario. Section
G.4.1.2 reviews the results of the comparison of constituent concentrations with soil target clean-
up levels for the protection of ground water and RBTCL.s derived for soil in the residential Site use
scenario.
G.4.1.1 Commercial/Industrial Site Use Results
In surface and subsurface soils in Areas A, B, and D, the existing maximum concentrations of
constituents are lower than the RBTCL.s (except the 1 E-06 RBTCL for Area B PCDD/PCDF
assuming no degradation occurs), and the maximum concentrations of constituents are lower than
the ground water protection soil target levels. Thus, based on RBTCL.s and protection of ground
water, no remediation of soils is likely to be required in any of these areas.
The Area C maximum concentrations of pentachlorophenol in surface and subsurface soil are
below the RBTCLs at the 1 E-5 risk level derived assuming that degradation occurs. The Area
C maximum concentration of pentachlorophenol in surface soil exceeds the RBTCL.s at the 1 E-5
risk level for the on-site worker derived assuming degradation does not occur. The Area C
maximum concentration of pentachlorophenol in subsurface soil is below the RBTCL.s at the 1 E-6
risk level derived assuming degradation does not occur, but exceeds the RBTCL for the on-site
worker at the 1 E-5 risk level assuming degradation does not occur. In addition, the maximum
concentrations of pentachlorophenol in Area C surface soil (3200 ppm) and subsurface soil (560
ppm) exceed the soil target level for the protection of ground water (95 ppm). Thus, remediation
may be required in Area C surface soil and subsurface soil.
The maximum concentrations of PCDD/PCDFs found in Area C surface soil exceed the human
health RBTCL.s and the ground water protection soil target clean-up level, indicating that
remediation may be required for Area C surface soils. Concentrations of PCDD/PCDF in Area
C subsurface soil are below RBTCL.s at the 1 E-5 risk level, and ground water protection values,
indicating no need for remediation of subsurface soils based on PCDD/PCDF.
G.4.1.2 Residential Site Use Results
The maximum concentrations of pentachlorophenol in Areas A, B and D soils are below the
RBTCLs for residential Site use. Areas A and D were not analyzed for PCDD/PCDF in surface
A :\PU BS\P ROJ E CTS\064 5008\5 1 O.A PG G-23 Juty, 1992
or subsurface soil. The maximum concentrations of PCDD/PCDF in Area B surface soil exceed
the RBTCL at the 1 E-6 risk level derived assuming degradation, and the RBTCL at the 1 E-5 risk
level derived assuming no degradation occurs. The maximum constituent concentrations in Areas
A, B and D soils do not exceed the soil target clean-up levels for the protection of ground water.
indicating that remediation of soils in these areas is likely not to be required based on risk.
The maximum concentration of pentachlorophenol in Area C surface soil exceeds the RBTCLs
at the 1 E-5 risk level derived assuming degradation occurs, and the RBTCL at the 1 E-4 risk level
derived assuming degradation does not occur. The maximum concentration of pentachlorophenol
in Area C subsurface soil exceeds only the RBTCL at the 1 E-6 risk level derived assuming no
degradation occurs.
The maximum concentration of pentachlorophenol in Area C surface soil (3200 ppm) and
subsurface soil (560 ppm}, however, exceeds the soil target level for the protection of ground
water (95 ppm). This indicates that both surface and subsurface soil may be required for the
protection of ground water.
The maximum concentration of PCDD/PCDF in Area C surface soils exceeds the RBTCL, and
the maximum concentration in Area C surface soil exceeds the ground water protection soil target
clean-up level. Thus, remediation may be required for Area C surface soils. However, the lowest
RBTCL (5E-06 ppm) for PCDD/PCDFs in surface soil is greater than two orders of magnitude
smaller than the frequently used surface soil clean-up level of 0.001 ppm. Because of the
precedent of using this target clean-up level, it is likely that it, or the value for the protection of
ground water, would be given preference here over the RBTCL (at the 1 E-06 risk level, assuming
degradation does not occur and assuming future residential Site use) for residential Site use.
G.4.2 ·comparison of Surface Water RBTCLs and ARARs
The surface water bodies evaluated here include Fire Pond, Medlin Pond, and the Western Ditch.
The North Carolina surface water standard for 2,3,7,8-TCDD is 1.3E-11 ppm (or 0.013 ppq). The
isomer 2,3,7,8 TCDD was not detected in any surface water samples on the Site. Most of the
PCDD/PCDFs in surface water at the Site were "octa" congeners. The State standard is for
2,3, 7,8-TCDD in surface water. Because the State standard is driven almost exclusively by
consumption of 2,3,7,8-TCDD that has bioaccumulated in fish, this standard is not applicable to
congeners other than 2,3,7,8-TCDD unless an adjustment for bioaccumulation is also made. If
the State standard were adjusted to reflect the differences in bioaccumulation of the congeners
detected in surface water on the Site, it would likely increase by several orders of magnitude.
Because the State standard is not considered appropriate for comparison with concentrations of
PCDD/PCDF found at this Site, it is not addressed further in this evaluation. It is also important
R:\P UBS\PROJECTS\0845008\51 O.A PG G-24 Juty, 1992
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to note, however, that not only is the State standard considered inappropriate, but it is also not
achievable because it is well below the laboratory detection limit for 2,3,7,8-TCDD.
Section G.4.2.1 reviews the results of the comparison of constituent concentrations with RBTCLs
derived for the commercial/industrial Site use scenario. Section G .4.2.2 reviews the results of the
comparison of constituent concentrations with RBTCLs derived for the residential Site use
scenario.
The results of the ecological evaluation show that remediation of surface water in Fire Pond and
Medlin Pond may be required to protect aquatic organisms.
G.4.2.1 Commercial/Industrial Site Use Results
All constituent concentrations in surface water bodies evaluated here are less than the RBTCLs
at the 1 E-5 risk level derived for commercial/industrial Site use. Maximum measured
concentrations exceed RBTCLs at the 1 E-06 risk level for PCDD/PCDF in Fire Pond surface
water. Thus, no remediation of surface water is likely to be required based on potential human
exposure to surface water if the Site remains commercial/industrial in the future.
G.4.2.2 Residential Site Use Results
In the residential Site use evaluation, maximum concentrations of pentachlorophenol and
PCDD/PCDF in surface water, except PCDD/PCDF in Fire Pond, are lower than RBTCLs at the
1 E-6 risk level. This suggests that remediation of surface water is not likely to be required for the
Western Ditch.
The maximum PCDD/PCDF concentrations in Fire Pond exceed the RBTCLs at the 1 E-4 risk
level for residential Site use. In the unlikely event that the Site is developed for residential use
in the future, Fire Pond surface water may require remediation.
G.4.3 Comparison of Sediment RBTCLs
There are no ARARs for the constituents of interest in sediment. Comparison of maximum
measured sediment concentrations of pentachlorophenol with RBTCLs indicates no remediation
is required based on assumed risk. Comparison of maximum measured sediment concentrations
of dioxin with RBTCLs indicates remediation of sediment in the Fire Pond Discharge Stream may
be required if 1 E-06 is selected as the remedial risk goal for commercial/industrial Site use.
Remediation of Fire Pond sediment may also be required if 1 E-06 is selected as the remedial
goal for residential Site use. It is unlikely that the Site will be developed for residential use in the
R :\P U BS\PROJ E CTS\084 5008\51 o .A PG G-25 Juty, 1992
future based· on current development in the area near the Site and the fact that an active
commercial/industrial facility currently operates on the Site.
G.4.4 Comparison of Ground Water RBTCLs and ARARs
Ground water was sampled off-Site and in three on-Site areas: the Former Lagoon Area, the
Eastern Area and the Western Area. The off-Site analysis was prepared for the
commercial/industrial Site use scenario which assumes that future off-site residents consume off-
site ground water as drinking water. The results of the comparison of RBTCLs and ARARs for
off-Site ground water assuming future commercial/industrial Site use is presented in Section
G.4.3.1. The on-Site analysis was prepared for the future residential Site use scenario because
this leads to the most health-protective result. Section G.4.4.2 presents the results of the
comparison of RBTCLs and ARARs for on-Site ground water assuming the Site is developed for
residential use.
G.4.4.1 Commercial/Industrial Site Use Results
The maximum concentrations of pentachlorophenol in off-Site ground water are well below the
RBTCL and the MCL. Thus, no remediation of pentachlorophenol in off-Site ground water is
required on the basis of either potential human health effects or to meet appropriate ground water
ARARs for pentachlorophenol.
Both a North Carolina Ground Water Standard and a proposed MCL exist for 2,3,7,8-TCDD.
These standards can be compared with the Local Off-Site Resident RBTCL for ground water.
The maximum concentrations of PCDD/PCDFs in off-Site ground water are below the RBTCL,
the proposed MCL and the North Carolina Ground water Standard. Thus, no remediation of
PCDD/PCDFs in off-Site ground water is required on the basis of RBTCLs or ARARs.
The North Carolina MCL for 2-chlorophenol was compared with maximum off-Site ground water
concentrations of this constituent. Only one sample had a detected concentration of
2-chlorophenol and this was an "estimated" value {designated by the "J" qualifier in the laboratory
results). Because the only detected value for 2-chlorophenol in Off-Site Area groundwater is an
"estimated" value, and because the sampling location in which this value was estimated is located
within the bounds of the area that will be impacted by pumping of Site ground water, Off-Site Area
ground water is not identified as an area that may require remediation.
A :\PU BS\PROJE CTSID84 5008\51 0.APG G-26 July, 1992
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G.4.4.2 Residential Site Use Results
On-Site ground water was evaluated for the hypothetical residential future use scenario. The
results of the comparison of Former Lagoon and Eastern Area constituent concentrations with
RBTCLs and ARARs are presented below. No constituent concentrations exceeded RBTCLs or
ARARs in the Western Area. Therefore, the Western Area is not discussed further in this
evaluation.
Former Lagoon Area Results
The maximum concentrations of pentachlorophenol in the Former Lagoon Area exceed the
RBTCLs and the MCL. These results suggest that remediation of pentachlorophenol may be
required in the Former Lagoon Area.
The maximum concentrations of PCDD/PCDF in the Former Lagoon Area exceed the RBTCLs,
State standard, and the proposed MCL, indicating that remediation of PCDD/PCDF may be
required in the Former Lagoon Area.
The maximum measured concentration of 2-chlorophenol in Former Lagoon Area ground water
is below the State MCL for this constituent, indicating that remediation is not required based on
this ARAR.
Eastern Area Results
The maximum concentration of pentachlorophenol in the Eastern Area exceeds the MCL and the
RBTCL. These results suggest that remediation of pentachlorophenol may be required in the
Eastern Area.
The maximum concentration of PCDD/PCDF in Eastern Area ground water is higher than the
RBTCL, the State standard and the proposed MCL. Thus, remediation of Eastern Area ground
water may be required at this Site.
The maximum measured concentration of 2-chlorophenol in Eastern Area ground water exceeds
the State MCL for this constituent. Thus, remediation of Eastern Area ground water may be
required.
A :\PU BS\P AOJ E CTS\064 5008\51 0.A PG G-27 Ju~. 1992
G.4.s: Comparison of Fish RBTCLs and Existing Concentrations
There are no ARARs for the constituents of interest available for the evaluation of fish tissue.
Pentachlorophenol was not detected in fish tissue in either Fire Pond or Medlin Pond. The
maximum concentration of PCDD/PCDF in fish tissue in Fire Pond in the commercial/industrial
scenario exceeds the RBTCL at the 1 E-5 risk level for PCDD/PCDF in fish tissue. The maximum
concentration of PCDD/PCDF in fish tissue in Medlin Pond in the commercial/industrial scenario
exceeds the RBTCL at the 1 E-6 risk level. The maximum concentration of PCDD/PCDF exceeds
the RBTCL in Fire Pond at the 1 E-5 risk level in the future residential site use scenario. If the
Site is developed for residential use in the future, some action restricting consumption of fish from
Fire Pond may be required.
G.5 Summary and Conclusions
This Appendix has derived RBTCLs for the former Koppers Company, Inc. Site in Morrisville,
North Carolina. These RBTCLs are based upon potential assumed carcinogenic risks to human
receptors assuming two different future potential Site use conditions. The human health RBTCLs
were determined using the potential assumed carcinogenic risks estimated in the risk assessment
for this Site, which was conducted following EPA guidance and in accordance with standard risk
assessment methodology. Parallel analyses for ecological receptors suggest that remedial action
may be necessary for surface water in Fire Pond and Medlin Pond. However, because of the
uncertainty associated with the screening values used to estimate ecological risk, RBTCLs are
not calculated for ecological receptors.
As discussed in Section G.1, remediation decisions should be based on the comparison of
average constituent concentrations, not upper-bound concentrations, because of the inherent
conservatism built into the process. However, at the request of EPA, comparisons were made
with maximum constituent concentrations. It is important to note, however, that, in most cases,
use of the average constituent concentration instead of the maximum concentration does not
change the recommendations made here.
This Section is divided into four sub-sections. Section G.5.1 presents a summary of the RBTCLs
derived in this evaluation. Section G.5.2 summarizes the comparison of constituent
concentrations in various media with RBTCLs and ARARs available for those constituents.
Section G.5.3 presents a summary of the findings in this evaluation.
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G.5.1 · Summary of Human Health RBTCLs
The human health RBTCLs derived in Section G.2 indicate that, based on potential assumed
risks, few environmental media and few areas of the Site may require remediation. The following
areas have maximum constituent concentrations that exceed RBTCLs at the 1 E-04, 1 E-05 or 1 E-
06 risk levels in either or both potential future site use scenarios:
• surface soil Area B (dioxin at 1 E-06 for commercial/industrial use;
dioxin at 1 E-05 for residential use);
• surface soil Area C (pentachlorophenol at 1 E-05 for commercial/industrial use;
pentachlorophenol at 1 E-04 for residential use; dioxin at 1 E-04 for commercial/industrial
use and residential use);
• subsurface soil Area C (pentachlorophenol at 1 E-05 for commercial/industrial use and
1 E-06 for residential use; dioxin at 1 E-06 for commercial/industrial use and residential
use);
• surface water in Fire Pond (dioxin at 1 E-06 for commercial/industrial use; dioxin at 1 E-04
for residential use);
• sediment in Fire Pond Discharge Stream (dioxin at 1 E-06 for commercial/industrial use);
• sediment in Fire Pond (dioxin at 1 E-06 for residential use);
• on-Site ground water in the Eastern Area (pentachlorophenol at 1 E-05 and dioxin at 1 E-
04 for residential use);
• on-Site ground water in the Former Lagoon Area (pentachlorophenol at 1 E-04 and dioxin
at 1 E-04 for residential use);
• fish in Fire Pond (dioxin at 1 E-05 for commercial/industrial and residential use); and
• fish in Medlin Pond (dioxin cl.I 1 E-06 for commercial/industrial use).
Because the Site is likely to remain commercial/industrial in the future, remediation at this Site
(based on risk) may be required in the following areas:
• surface soil in Area C;
• on-Site ground water in the Former Lagoon and the Eastern Area (based on MCLs); and
• fish from Fire Pond.
These areas were those in which the potential assumed carcinogenic risk estimated in the risk
assessment was greater than 1 E-5 for one or more of the hypothetical potential receptors, or the
RBTCLs derived were substantially lower than the existing constituent concentrations.
R:\P UBS\PAOJE CT S\0845008\5 1 O.A PG G-29 July, 1992
In addition to the areas identified above based on the results of the human health evaluation,
surface water in Fire Pond and in Medlin Pond may require remediation based on the results of
the aquatic ecological evaluation.
G.5.2 Summary of Comparison of ARARs and RBTCLs
The following sections summarize the results of the comparison of RBTCLs, ARARs and
. guidelines with existing maximum constituent concentrations in the various media investigated in
the baseline risk assessment. Table G-8 identifies the media and areas that may require
remediation, and summarizes the remedial goals recommended by Beazer East, Inc. for this Site.
G.5.2.1 Soil Summary
The results of the comparison of constituent concentrations with RBTCLs and relevant guidelines
indicates that only soil in Area C may require remediation. The potential need for remediation
in Area C surface and subsurface soils is supported by the results of the analysis of
pentachlorophenol in assumed future use scenarios; the maximum surface and subsurface soil
concentrations (3200 ppm and 560 ppm, respectively) exceed the soil level derived for the
protection of ground water (95 pm) and some of the relevant RBTCLs.
The potential need for remediation in Area C surface soils is also supported by the results of both
the commercial/industrial Site use and residential Site use analyses of PCDD/PCDF. In both
assumed future Site use scenarios, the maximum concentration of PCDD/PCDF in surface soil
(0.27 ppm) exceeds the RBTCLs derived for the receptors at various risk levels and the soil target
clean-up level for protection of ground water (0.007 ppm). Subsurface soil in Area C does not
require remediation based on PCDD/PCDF because, in all scenarios, maximum concentrations
of PCDD/PCDF are below RBTCLs and soil levels for the protection of ground water.
G.5.2.2 Surface Water Summary
As discussed in Section G.4.2, the State standard for 2,3,7,8-TCDD is not considered applicable
at this Site. lri this analysis, constituents in surface water in Fire Pond, Medlin Pond, and in the
Western Ditch were compared with RBTCLs. The results of these analyses show that the Fire
Pond may require remediation if the Site becomes residential in the future. If the Site remains
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commercial/tndustrial, as is more likely, no surface water remediation is required based on the
human health RBTCLs derived here.
The results of the aquatic ecological evaluation, however, identify surface water in Fire Pond and
Medlin Pond as areas that may require remediation.
G.5.2.3 Ground Water Summary
Ground water was evaluated off-Site and on-Site. Pentachlorophenol and PCDD/PCDF
concentrations in several ground water areas of interest exceeded RBTCLs and other ARARs.
Maximum concentrations of 2-chlorophenol in ground water in the Eastern and Off-Site Areas
exceed the North Carolina MCL for this constituent. The results of the off-Site ground water and
on-Site ground water analyses are presented below.
Off-Site Summary
The maximum concentrations of both pentachlorophenol and PCDD/PCDF are less than the most
conservative of either the RBTCL or ARAR for that constituent in ground water. Because no one
currently has access to off-Site ground water for drinking water, and no one is expected to in the
foreseeable future, and because no existing concentrations exceed RBTCLs or ARARs, no
remediation of off-Site ground water is required.
The maximum concentration of 2-chlorophenol in off-Site ground water exceeds the State MCL,
however, as described previously, Off-Site Area ground water is not specifically identified as an
area of potential remediation because the zone of influence of on-Site ground water remediation
will address the potential assumed risk attributable to 2-chlorophenol.
On-Site Summary
Two on-Site ground water areas may require remediation based on potential assumed risk only
if the Site becomes residential in the future: the Former Lagoon Area and Eastern Area. For this
hypothetical future use scenario, the maximum concentration of pentachlorophenol in the Former
Lagoon Area ( 1.49 ppm) exceeds both the MCL (0.001 ppm) and the RBTCLs. This indicates
that remediation of Former Lagoon Area ground water may be required.
The maximum concentration of PCDD/PCDF (BE-B ppm) in the Former Lagoon Area exceeds the
RBTCLs, the proposed MCL (5E-B ppm), and the State standard (2E-10 ppm) for dioxin. These
data indicate that remediation of Former Lagoon Area ground water may be required. Although
the State standard for dioxin is lower than the MCL, it may be appropriate to set the remediation
R:\P UBS\ PROJ E CTS\084 5008\51 O.A PG G-31 July. 1992
goal for dioxin at the MCL because exposure to on-Site ground water as a drinking water source
is extremely unlikely, and the MCL is considered protective by the EPA. Even if the state
standard were selected, however, the practical quantitation limit for dioxin in water is 50 ppq (5E-8
ppm), which would be used as a default remedial goal in place of the state standard (2E-1 0 ppm).
In Eastern Area ground water, the maximum concentration of pentachlorophenol (0.05 ppm)
exceeds the RBTCL (0.004 ppm) and the MCL (0.001 ppm). The maximum concentration of
PCDD/PCDF in Eastern Area ground water (2E-7 ppm) also exceeds the RBTCLs, the proposed
MCL (5E-8 ppm) and the State standard (2E-10 ppm}, indicating that remediation may be
required. As stated above, the MCL is the clean-up goal recommended by Beazer East, Inc. for
ground water at this Site.
The maximum concentration of 2-chlorophenol in Eastern Area ground water exceeds the State
MCL for this constituent indicating that remediation of Eastern Area ground water may be
required.
G.5.2.4 Fish Summary
The maximum concentration of PCDD/PCDF in fish from Fire Pond (4E-5 ppm) exceeds the
RBTCLs at the 1 E-05 and 1 E-06 risk levels (5E-6 ppm and 5E-7 ppm). This indicates that a
remedial measure restricting use of fish from Fire Pond may be needed.
G.5.3 Clean-Up Levels Evaluation Summary
Based on a comparison of existing maximum concentrations of pentachlorophenol and
PCDD/PCDF with human health RBTCLs, ARARs and other clean-up guidelines, and the results
of the ecological evaluation, the following media may require remediation at the Former Koppers
Company, Inc. Site in Morrisville, NC:
• surface and subsurface soil in Area C;
• surface water in Fire Pond;
• surface water in Medlin Pond;
• on-Site ground water in the Former Lagoon and Eastern Areas; and
• fish from Fire Pond.
Table G-8 presents a summary of the remedial goals presented in this evaluation.
The recommendations made in this appendix were derived from many conservative assumptions
and, thus, are health protective. Many of the RBTCLs derived here are based on the
A :\PU BS\PROJE CTS\0845008\51 O.A PG G-32 July. 1992
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assumptions-that the Site is developed for residential use in the future. Because it is unlikely that
the Site will become residential, RBTCLs derived for residential use are not appropriate for this
Site.
R:\P UBS\PAOJE CTS\0645008\5 1 O.A PG G-33 July, 1992
REFERENCES FOR APPENDIX G
Anderson, E., N. Browne, S. Duletsky, J. Tamig and T. Warn. 1985. Development of Statistical
Distributions for Ranges of Standard Factors Used in Exposure Assessments. Office of
Health and Environmental Assessment. EPA/600/8-85/010, Washington, D.C.
Eisler, R. 1986. Dioxin Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review.
Biological Report 85 (1.8) U.S. Fish and Wildlife Service. Laurel, MD.
Keystone Environmental Resources, Inc. (KER) 1992a. "Development of Soil Clean-up Goals
Protective of Groundwater Quality." Former Koppers Company, Inc. Superfund Site,
Morrisville, NC. December 1991.
Keystone Environmental Resources, Inc. (KER) 1992b. Remedial Investigation Draft Report,
Former Koppers Company, Inc. Superfund Site, Morrisville, North Carolina. June 1991.
Koporec, K. 1991. U.S. EPA Region IV. Personal Communication, April 23, 1991.
Oak Ridge National Laboratory (ORNL}. 1986. User's Manual for Ecological Risk Assessment.
Rupp, E.M., F.L. Miller and C.F. Baes Ill. 1980. Some Results of Recent Surveys of Fish and
Shellfish Consumption by Age and Region of U.S. Residents. Health Physics 39:165-175.
State of North Carolina (NC DNRCD). 1989. 1987 Ambient Air Quality. Department of Natural
Resources and Community Development, Division of Environmental Management. May
1989.
U.S. EPA. 1980. Dietary Consumption Distribution of Selected Food Groups for the U.S.
Population. Office of Pesticides and Toxic Substances. EPA 560/11-80/012.
U.S. EPA. 1986. Quality Criteria for Water. 1986. Office of Water Regulations and Standards.
EPA 440/5-86/001.
U.S. EPA. 1988a. Recommendations for and Documentation of Biological Values for Use in Risk
Assessment. Office of Research and Development, Cincinnati, OH. PB88-179874.
U.S. EPA. 1988b. Review of Ecological Risk Assessment Methods. EPA/230/10-88/041.
U.S. EPA. 1988c. Superfund Exposure Assessment Manual. Office of Emergency and
Remedial Response, Washington, D.C. EPA/540/1-88/001.
U.S. EPA. 1989a. Ecological Assessment at Hazardous Waste Sites: A Field and Laboratory
Reference. EPA/600-3-89/013.
U.S. EPA. 1989b. Exposure Factors Handbook. Office of Health and Environmental
Assessment, Washington, D.C. EPA/600/8-89/043.
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U.S. EPA. -1989c. Risk Assessment Guidance for Superfund. Volume I: Human Health
Evaluation Manual (Part A). Interim Final. Office of Emergency and Remedial Response,
Washington, D.C. EPA 540/1-89/002.
U.S. EPA. 1989d. Risk Assessment Guidance for Superfund. Volume II: Environmental
Evaluation Manual (Part B). Interim Final. Office of Emergency and Remedial Response,
Washington D.C. EPA 540/1-89/001.
U.S. EPA. 1990. Health Effects Assessment Summary Tables (HEAST}. Third and Fourth
Quarters, F.Y. 1990. Office of Solid Waste and Emergency Response, Washington, D.C.
U.S. EPA. 1991 a. Integrated Risk Information System (IRIS}. Environmental Criteria and
Assessment Office, Cincinnati, OH.
U.S. EPA. 1991 b. Supplemental Region IV Risk Assessment Guidance. U.S. EPA, Region IV,
Atlanta, GA.
U.S. EPA. 1992. Region IV Waste Management Division Screening Values for Hazardous
Waste Sites. Version Dated 1/27/92.
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CONTENTS
(Cont'd)
~ECf~~~(lJ)
JUL 2 0 1992 &,!.am
6.5.3.1 Muskrat Characterization ......................... 6-21
6.5.3.2 Belted Kingfisher Characterization ................... 6-21
6.6 Ecological Evaluation Summary .................................. 6-21
7.0 SOURCES OF UNCERTAINTY ....................................... 7-1
7.1 Uncertainties Associated with Human Health Evaluation ................. 7-1
7.1.1 Hazard Identification ..................................... 7-1
7.1.2 Dose-Response Assessment ............................... 7-1
7.1.2.1 Animal-to-Human Extrapolation in Noncarcinogenic Dose-
Response Evaluation ............................. 7-2
7 .1.2.2 Evaluation of Carcinogenic Dose-Response ............. 7-2
7.1.2.3 Compound-to-Compound Extrapolation ................ 7-5
7.1.3 Exposure Assessment .................................... 7-5
7.1.3.1 Estimation of Exposure Point Concentrations ............ 7-5
7.1.3.2 Estimation of Exposure Dose ....................... 7-6
7.1.4 Risk Characterization .................................... 7-7
7.1.4.1 Risk from Multiple Compounds ...................... 7-7
7.1.4.2 Combination of Several Upper-bound Assumptions ....... 7-8
7.1.5 Summary of Sources of Uncertainty in the Human Health Evaluation .. 7-9
7.2 Uncertainties Associated with the Ecological Evaluation ................. 7-9
8.0 SUMMARY AND CONCLUSIONS ..................................... 8-1
8.1 Human Health Evaluation Summary ................................ 8-1
8.2 Ecological Evaluation Summary ................................... 8-2
8.3 Baseline Risk Assessment Summary ............................... 8-2
9.0 CLEAN-UP LEVELS EVALUATION ................................... 9-1
9.1
9.2
9.3
Derivation of Risk Based Target Clean-up Levels (RBTCLs) .............. 9-1
9.1.1 Human Health Evaluation ................................. 9-2
9.1.2 Ecological Evaluation .................................... 9-3
Comparison of RBTCLs and ARARs ............................... 9-3
Summary and Recommendations 9-6
REFERENCES
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CONTENTS
(Cont'd}
APPENDICES
A HAZARD IDENTIFICATION AND SUPPLEMENTAL DATA ANALYSIS
A-1 HAZARD IDENTIFICATION
A-2 SUPPLEMENTAL DATA ANALYSIS
B DOSE-RESPONSE SUMMARIES
C ABSORPTION ADJUSTMENT FACTORS
D
C-1 ABSORPTION ADJUSTMENT FACTORS
C-2 DERIVATION OF INHALATION FACTORS
C-3 SKIN PERMEABILITY CONSTANTS
REVIEW OF THE SCIENTIFIC LITERATURE
E ADDITIONAL EXPOSURE ASSESSMENT INFORMATION
E-1 CONSTITUENT FATE AND TRANSPORT
E-2 HYPOTHETICAL VEGETABLE INGESTION SCENARIO
EN3l
E-3 HYPOTHETICAL ON-SITE RESIDENTIAL USE OF GROUND WATER DURING
SHOWERING
E-4 EXPOSURE SPREADSHEETS (SEPARATE DOCUMENT)
F ECOLOGICAL EVALUATION -ADDITIONAL INFORMATION
F-1 HABITAT AND WILDLIFE SURVEY
F-2 CALCULATION OF POTENTIAL EFFECTS TO MUSKRAT
F-3 CALCULATION OF POTENTIAL EFFECTS TO BELTED KINGFISHER
F-4 EVALUATION OF POTENTIAL EFFECT ON THREATENED, RARE, OR
ENDANGERED SPECIES
G ADDITIONAL CLEAN-UP LEVELS EVALUATION INFORMATION
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potential exposure to constituents by muskrats inhabiting Fire Pond was 0.11 which falls at the
extreme lower end of the range of "possible concern" defined by EPA. The toxicity quotient
calculated for the belted kingfisher was 0.60, which is also at the extreme lower end of the range
of "possible concern" defined by EPA.
Clean-up Levels Evaluation
The results of the aquatic ecological evaluation in Fire Pond and Medlin Pond indicate that certain
constituents pose "possible concern", as defined by EPA, to aquatic receptors. Our constituent,
dioxin, was of "high concern", as defined by EPA, for aquatic receptors assumed to be exposed
to surface water in Fire Pond. The toxicity screening values used to estimate the potential risk
to aquatic receptors in the surface water of these ponds were provided by EPA Region IV, and
are intended for screening purposes only. Because the screening showed several constituents
resulted in toxicity quotients of "possible concern" in Fire Pond and Medlin Pond, and one of "high
concern" in Fire Pond, the surface water in Fire Pond and Medlin Pond were identified as media
possibly requiring remediation at this Site.
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Area, the Fire Pond, and the Former Lagoon and Cellon Treatment Process Areas). Beazer
Materials and Services, Inc. entered into discussions concerning a Consent Order with EPA
Region IV in December 1988, and signed the Consent Order on March 14, 1989.
As previously stated, the Morrisville Site is the location of a current laminating facility and a former
wood treating process, referred to as the Cellon process. The plant has produced glued-
laminated wood products since 1962. The Cellon process was operated from 1968 to 1975, at
which time it was dismantled. Waste water from the Cellon process settled in on-Site effluent
lagoons. Environmental investigations undertaken in the late 1970s and early 1980s revealed
pentachlorophenol present in on-Site ground water wells. On-Site soil removal was undertaken
in 1980 and 1986.
Sampling of on-Site soils, suriace water and ground water was conducted at various times
throughout the late 1970s and 1980s. In August 1987, Keystone prepared a report entitled
"Summary of Existing Data for Previously Operated Property, Koppers Company, Inc., Raleigh,
North Carolina Site." This report, which was submitted to the North Carolina Department of
Environment Health and Natural Resources (NCDEHNR), summarizes previous environmental
investigations of ground water, surface water, sediments, and soils at the Site.
In additjon to on-Site ground water monitoring, Beazer East, Inc. initiated a domestic well
sampling program of potentially affected wells in 1986. Results of this sampling indicate the
presence of very low levels of pentachlorophenol and isopropyl ether in domestic wells located
generally to the north and northwest of the Site.
Pursuant to an agreement with the Wake County Department of Health and the State of North
Carolina, Beazer has provided an alternative potable water supply to any resident who owns/or
uses a well in which any level of pentachlorophenol or isopropylether was detected. Beazer has
carried out its agreement by installing approximately three miles of water line to provide a public
water supply for affected residents. In 1989 Beazer entered into an Administrative Consent Order
with EPA for the installation of the water line.
The RI report presents the results of the investigation of potential ground water source areas on
the Site. Phenolics, principally pentachlorophenol, and dioxins/furans have been detected in on-
Site surface and subsurface soils, with the highest pentachlorophenol concentrations occurring
in the Former Lagoon and Eastern Areas. Surface water and sediment sampling conducted in
the Fire Pond, Medlin Pond (off-Site), and associated drainage ditches showed pentachlorophenol
and dioxins/furans concentrations above detectable levels in both media. The RI fully
characterizes the potential areas of interest at the Site. This baseline risk assessment is based
on the results of the RI.
A :\P UBS\PROJE CTS\084 5008\51 O.S 1 1-3 July, 1992
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z--L.C-Z-J.
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0-.5 2-4
238 U 123 U
887 ND
540 1. 1
Source: Keystone, 1992
-0-.5 1.5-3.5
286 U 122 U
1590 178
1000 5.9
LEGEND
* -SEDIMENT SAMPLE LOCATION
0-. 5 -DEPTH (FEET)
232 -PENTACHL0A0PHEN0L ('4Q/Kg)
411 -TOTAL ACID EXTRACTABLE PHENOLICS ('4Q/Kg)
26 -2,3, 7,8-TCDD EQUIVALENT CONCENTRATION (ng/Kg)
ND -NOT DETECTED (ALL INDIVIDUAL PHENOLIC CONSTITUENTS
WERE BELOW THEIR RESPECTIVE DETECTION LIMITS)
NA -NOT ANALYZED
U -ANALYTE NOT DETECTED AT THE CONCENTRATION LEVEL SHOWN
6/4/90 10/18/90
0-.5 1-1.5
350 U 168 U
ND 974
890 590
I
SCALE (FEET)
0 30 60
0-.5
242 U
ND
180
S36
APPROX.
BOO'SOUTHEAST ~ _,-¥" ,,,,. ~~
~ 0-.5
232 U
411
26
Q
FIGURE 2-10
Sediment Water Quality in Medlin Pond and Medlin Pond Discharge Streams
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The estimate·d potential upper-bound excess lifetime cancer risk for use of on-Site ground water
as potable water supply by hypothetical future on-Site residents in Area D (1.48E-07, Table 5-16)
is less than the EPA's point of departure risk ol 1 E-06, indicating that, based on risk, remediation
of the on-Site ground water in the Western Area of the Site is not needed. Only the estimated
potential upper-bound excess lifetime cancer risks associated with hypothetical future potable use
of ground water in Areas A and B (Eastern Area), and C (Former Lagoon and Ce/Ion Process
Area), exceed the EPA's target risk range ol 1 E-06 to 1 E-04 (Tables 5-13, 5-14, 5-15). Because
estimated upper-bound assumed risks are assumed to be additive, the estimated total upper-
bound cancer risks for hypothetical on-Site residents in these areas also exceed the target risk
range. In Areas A and B, the Eastern Area, the majority of the estimated potential assumed risks
are associated with exposure to dioxins and lurans (Tables 5-13 and 5-14).
As discussed above, because surrounding off-Site residents are currently using city water as a
potable water supply and the Site is also currently supplied by city water lines, it is likely that the
hypothetical on-Site future residents would also use city water, and not ground water as a potable
water supply.
Potential residential exposures to constituents in ground water via inhalation of volatiles while
showering results assumed risks well below EPA's point of departure. Thus, assumed risks from
exposure to on-Site ground water while showering are not of concern at this site.
5.3 Summary of Estimated Potential Assumed Risks
This baseline risk assessment has shown that no potential adverse assumed noncarcinogenic
health risks are expected to occur following potential exposure to constituents in any of the
environmental media evaluated (surface soils, subsurface soils, sediments, surface water, fish and
ground water). The baseline risk assessment has also shown that, with the exception of potential
exposure to surface soil in Area C, hypothetical future use of on-Site ground water as a potable
water supply, and hypothetical future use of Fire Pond as a swimming hole and source of fish for
consumption by hypothetical on-Site residents (which is an unlikely occurrence), the estimated
potential assumed risks associated with all PEPs fall within or below the U.S.EPA's target risk
range.
Section 8.0 presents recommendations for remediation of certain media at the Site based on
ssumed risk. Section 9.0 compares risk-based target clean-up levels with standards and other
applicable and relevant or appropriate requirements (ARARs). In some cases, although
remediation may not be required based on assumed risk, recommendations for remediation may
R:\PUBS\PROJECTS\0845008\51 O.S5 5-8 July, 1992
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{'
6.0 ECOLOGICAL EVALUATION
This Section reports the results of the ecological evaluation for the Former Koppers Company,
Inc. Site in Morrisville, North Carolina. The ecological evaluation is part of the baseline risk
assessment for the Site. This evaluation was prepared using the following EPA guidance
documents: Risk Assessment Guidance for Superfund: Volume II, Environmental Evaluation
Manual (U.S. EPA 1989e), Recommendations for and Documentation of Biological Values for Use
in Risk Assessment (U.S. EPA, 1988a); Quality Criteria for Water, 1986 (U.S. EPA, 1986b);
Review of Ecological Risk Assessment Methods (U.S. EPA 1988b); and Ecological Assessment
at Hazardous Waste Sites (U.S. EPA, 1989a). Although formal guidance for evaluating potential
ecological effects from a site is not presented in the available guidance documents, the
documents do provide an overall framework for evaluating environmental effects. Despite the
absence of formal guidance, a scientifically defensible and appropriate approach for the
evaluation of potential ecological effects is presented here.
The first step of this ecological evaluation is the characterization of the Site and surrounding area,
and is presented in Section 6.1. This is followed by the selection of the indicator species in
Section 6.2 and the selection of constituents of potential interest in Section 6.3. Section 6.4
describes the aquatic assessment in which potential effects in aquatic species are characterized.
Section 6.5 describes the riparian assessment in which potential effects in mammals and birds
are characterized. Conclusions of the ecological evaluation are summarized in Section 6.6 and
Section 8.2 of the baseline risk assessment.
In addition to the analysis presented in this section, Appendix F contains additional information
for the ecological evaluation. Appendix F-1 discusses the Wildlife and Habitat Survey; Appendix
F-2 presents the Calculation of Potential Effects to Muskrat; Appendix F-3 presents the
Calculation of Potential Effects to Belted Kingfisher; and Appendix F-4 discusses the Evaluation
of Potential Threatened, Rare or Endangered Species.
R:\PUBS\PROJECTS\0845008\51 O.S6 6-1 Juty, 1992
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For 2,3,7,8-TCDD (dioxin), the LOEL guidance values for the protection of freshwater aquatic life
were derived on the basis of fish consumption rates for humans (U.S. EPA, 1984). EPA derived
these guidance values for dioxin by comparing calculated freshwater fish concentrations with U.S.
Food and Drug Administration (FDA) health advisories. The FDA health advisories determined
concentrations of dioxin in fish that are considered acceptable for human consumption. The
LOELs for dioxin that EPA lists as guidance values were back-calculated from the fish dioxin
concentrations determined by FDA and an assumed dioxin BCF of 5000. Thus, the LOEL
guidance values are not a direct measure of the potential toxicity of dioxin to fish. The AWQC
document on dioxin, however, does list some data on the toxicity of dioxin to aquatic species.
The dioxin AWQC document presents the following information: "the available information
indicates that acute values for some freshwater animal species are> 1.0 ug/I; some chronic values
are <0.1 ug/I, and the chronic value for rainbow trout is <0.001 ug/I" (U.S. EPA, 1984). Therefor~.
Table 6-2 lists the acute value for dioxin as 1.0 ug/I and the chronic value as 0.001 ug/1. These
data are scientifically appropriate and defensible as they are based on toxicity studies on aquatic
organisms rather than back-calculated from FDA health advisories for potential human exposure.
The Water Management Division of EPA Region IV has developed screening values which were
initially provided to permit writers in order to assist them in the evaluation of wastewater
discharges (U.S. EPA, 1991c). These screening values have been adopted by the Region IV
Superfund Program for use in the initial screening of ambient surface water data (U.S. EPA,
1992). The values were derived from published EPA ambient water quality criteria documents
with safety factors applied. A safety factor of ten is used when the data concerning the acute
toxicity of a compound to aquatic organisms are limited. A safety factor of ten is also applied to
acute aquatic toxicity data to derive chronic toxicity values when these are not available. These
acute and chronic toxicity values are designed to be used for screening purposes and they are
included in Table 6-2.
Pentachlorophenol values are pH dependent. The values recommended by EPA for
pentachlorophenol are based on a pH of 6.0 for both the acute and chronic criteria. As reported
by U.S. EPA Region IV (U.S. EPA, 1992), the screening criteria recommended by Region IV need
to be adjusted using the relationship presented in the AWQC for pentachlorophenol to reflect the
pH of the surface water bodies on and near the Site. In order to address this issue, pH data from
surface water at and near the Site were obtained. The pH values for Fire Pond and Medlin Pond
are reported in Table 6-3. (These pH data come from Table 4-35 of the RI report.)
Using the relationship from the AWQC for pentachlorophenol, acute and chronic criteria values
were calculated for each of the pH values presented in Table 6-3. To develop appropriate acute
criteria values, the lowest calculated concentration for Fire Pond (4.27 ug/L) and Medlin Pond (8.2
ug/L) are selected as acute criteria for pentachlorophenol for the revised risk assessment.
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To develop a·ppropriate chronic criteria values, the lower average of the Round 1 or Round 2 data
for Fire Pond and Medlin Pond were selected. Round 1 and Round 2 data were collected at
different times during the year. To be conservative the lower average values were used in the
evaluation of potential chronic effects. This results in a calculated chronic criteria value for
pentachlorophenol for Fire Pond of 4.91 ug/L and for Medlin Pond of 10.14 ug/L.
From the data in Table 6-2, benchmark concentrations were selected for the evaluation of bluegill
as an indicator species. In order to be conservative, the lowest value among the acute AWQC
or LOEL guidance value, the bluegill acute LOEL or the EPA Region IV screening acute value
was selected as the acute benchmark concentration. Because there were no chronic LOELs
specific to bluegill, the lower value between the chronic AWQC or LOEL guidance value or the
EPA Region IV screening chronic value was selected as the chronic benchmark concentration.
No chronic values were available for 2,3,5,6-tetrachlorophenol. Therefore, following EPA Region
IV guidance, a safety factor of 10 was applied to the acute value of 140 ug/L to derive a chronic
value of 14 ug/L.
6.4.2 Exposure Evaluation
Bluegills are assumed to inhabit the surface water bodies of Fire Pond and Medlin Pond. As
aquatic species, bluegill are potentially exposed to constituents dissolved in water and to
constituents bound to sediments or suspended solids.
Aquatic species may be exposed to constituents in the water through water ingestion, uptake
through the gills, dermal absorption, and ingestion of food or suspended solids. The extent of
their exposure to various constituents will, in part, depend on the movement of the constituents
through the water column. An important characteristic that influences the concentration of
constituents in the water column and bottom sediments is the hydrophobic nature of the
constituent. Hydrophilic constituents will tend to stay dissolved in the water column while
hydrophobic constituents may adsorb to suspended solids in the water column or accumulate in
the bottom sediments.
Benthic organisms and other aquatic species that live in close association with sediments may
potentially be exposed to constituents in the sediments through ingestion and dermal absorption.
Constituents in the sediments may be bound to individual sediment particles or dissolved in
interstitial water. Because of the lack of appropriate ecotoxicological data in this area, this
exposure route is not estimated for aquatic species in this evaluation.
In evaluating the potential for acute toxicity effects, it was conservatively assumed that the
receptor contacts the maximum constituent concentration in the surface water for four days of
A:\P U BS\PROJE CTS\0845008\5 1 0.S6 6-10 July, 1992
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continued exposure. This is a conservative assumption because the medium is fluid, the
measured constituent concentrations will mix and not remain steady, and it is unlikely that a
receptor would be exposed to the maximum measured concentration of each constituent detected
in the surface water for a prolonged period of exposure. In evaluating the potential for chronic
toxicity effects, it was assumed that the receptor is continuously exposed to the mean
concentration of the constituent in surface water.
6.4.3 Characterization of Potential Aquatic Impacts
In this assessment, the potential for assumed adverse effects in aquatic biota is estimated by the
toxicity quotient method prescribed by EPA (U.S. EPA, 1988b, ORNL, 1986). This method
involves the derivation of a toxicity quotient which is the ratio of an expected environmental
concentration (EEC) to a measured toxicological benchmark concentration (BC).
Toxicity Quotient (unitless) ~ EECf,µg/ L)
BC(µg/L)
The resulting ratio is arbitrarily classified as being of "no concern" if less than 0.1, of "possible
concern" if between 0.1 and 10, and of "high concern" if the ratio is greater than 10 (U.S. EPA,
1988b). No documentation has been provided for the rationale behind these classifications.
Acute and chronic toxicity quotients were calculated for the constituents in Fire Pond and Medlin
Pond. The acute benchmark concentrations were compared to the maximum observed
environmental concentrations measured for each of the constituents in Fire Pond and Medlin
Pond to generate the acute toxicity quotients presented in Table 6-4. The chronic benchmark
concentrations were compared to the mean observed environmental concentrations measured
for each of the constituents in Fire Pond and Medlin Pond to generate the chronic toxicity
quotients presented in Table 6-5.
The acute toxicity quotients for each of the constituents in Fire Pond and Medlin Pond were all
less than 0.1, which fall in the range of "no concern" as defined by EPA (U.S. EPA, 1988b). For
Fire Pond, the chronic toxicity quotients for each of the constituents, except TCDD-TE, were all
less than 0.1, which fall in the "no concern" range defined by EPA (U.S. EPA, 1988b).
The chronic toxicity quotient for TCDD-TE in Fire Pond is 16.5 which falls in the range of "high
concern" as defined by EPA (1988b). This value was obtained using the EPA Region IV chronic
screening value which contains a safety factor of 10. This value was derived from the ambient
water quality document for dioxin. The value is based on the value 0.0001 ug/L which comes
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from a 96 hour test on northern pike embryos and the resulting effect was "slight reduction in
growth up to 21 days". A safety factor of ten was applied to the northern pike value of 0.001 ug/L
to yield the value 0.00001 ug/L.
The National Criteria section of the Ambient Water Quality Criteria (AWQC) for dioxin states that
the chronic value for rainbow trout is 0.001 ug/L. This value was considered appropriate for this
assessment and results in a toxicity quotient of 0.165. The EPA has chosen to use a safety
factor of ten "when limited infonnation concerning aquatic toxicity of a compound is available."
Applying a safety factor of ten as suggested in the comments from EPA yields a chronic value
of 0.0001 ug/L, and a chronic toxicity quotient of 1.65 which is at the low end of the range of
"possible concern".
EPA's AWQC for dioxin are based upon 2,3,7,8-TCDD. This congener was not detected in
surface water in Medlin and Fire Ponds, however, other, higher chlorinated congeners were
detected. In order to compare measured concentrations of the higher chlorinated congeners to
the AWQC, their concentrations were converted to 2,3,7,8-TCDD equivalents using Toxic
Equivalency Factors (TEFs) derived for humans. These factors may not be appropriate for
aquatic species, because specific toxicity testing to derive TEFs has not been done for aquatic
species.
Chronic toxicity quotients for Medlin Pond were less than 0.1 for phenol; 2-nitrophenol; 2,4-
dimethylphenol; 2,4-dichlorophenol; and pentachlorophenol indicating "no concern". As shown
in Table 6-5, chronic toxicity quotients for 2,4,6-trichlorophenol; 2,4-dinitrophenol; 2,3,5,6-
tetrachlorophenol; 2-methyl-4,6-dinitrophenol and 2,3,7,8-TCDD were in the low end of the range
of "possible concern" as defined by EPA.
6.5 Riparian Assessment
The riparian assessment quantifies the potential impact of the Site on mammalian and avian
receptors (muskrat and belted kingfisher) through exposure through the food chain. The
estimated average daily dose for the receptor is compared to an acceptable dose in a manner
similar to the hazard index approach used for humans and the toxicity quotient method used for
aquatic species. The toxicity or dose-response infonnation is discussed in Section 6.5.1, and the
exposure evaluation is presented in Section 6.5.2. The characterization of potential effects is
found in Section 6.5.3.
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6.5.1 · Dose-Response Evaluation
Ideally, the units of concern in ecological risk assessments are populations or higher categories
such as communities or ecosystems. However, neither the theoretical underpinnings nor the
technical methodologies have been developed to carry out such analyses. EPA Region IV is
currently attempting to develop ecological risk assessment guidance, but until such time as these
methods are developed, individual assessments of exposed indicator species will be utilized.
Field data on the toxicological effects of constituent exposure to indicator species are difficult to
interpret. Only under laboratory conditions can doses and exposures be controlled and quantified.
Most of the data on natural populations are collected without any information on the
environmental dose or the conditions under which the exposures occurred. Usually the exposure
dose which resulted in an observed toxicological effect in the field is not quantifiable and therefore
is of limited utility in determining a species-specific dose-response value. The majority of data
used by the EPA to derive human reference doses and cancer slope factors are based on
mammalian studies from which the data are extrapolated to humans. In this evaluation, dose-
response values were derived for muskrat and belted kingfisher using the supporting literature
for EPA-derived human reference doses and other relevant literature sources. The derivation of
these values is explained in the following subsections.
6.5.1.1 Mammalian Dose-Response Values
Oral noncarcinogenic dose-response values for mammalian species are developed on the basis
of the toxicity studies used to determine the EPA-derived human oral reference doses. The
laboratory animal species and the type of study used to derive the human oral reference dose
are identified. Safety factors are then applied as necessary to extrapolate from a subchronic
study to a chronic study, or from a Lowest Observed Adverse Effect Level (LOAEL) to a No
Observed Adverse Effect Level (NOAEL) in order to obtain an oral dose-response value that is
applicable to mammals.
If the EPA-derived human oral reference dose was not based on a laboratory animal study, then
other literature sources are examined for mammalian toxicity studies. The most applicable
experimental data would be a chronic NOA EL for the indicator species or an equivalent laboratory
animal. However, if no NOAEL is available, a subchronic study or LOAEL is located. In either
case, appropriate uncertainty factors are applied in order to derive an oral dose-response value
that is applicable to mammals. The constituent-specific oral noncarcinogenic dose-response
values derived for the muskrat are summarized in Table 6-6.
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· 6.5.1.2 Avian Dose-Response Values
Dose-response information for the effects of dioxin on the kingfisher was not located in the
available scientific literature. Therefore, available toxicological literature on other avian species
was used. ENSR (1989) studied the effects of dioxin in the eastern bluebird and found a No
Observed Adverse Effect Level (NOAEL} for bluebird embryonic toxicity of 1,000 pg dioxin/g egg.
The NOAEL was back-calculated through the following equations to obtain the estimated dioxin
body burden for the bluebird. The bird-to-egg translocation factor is estimated as 4.8 percent
(0.048), the average weight of the eastern bluebird egg is 3 grams, and the average female
bluebird body weight is 34 g (0.034 kg) (ENSR, 1989). Using this information, the following
relationships are applied to calculate the steady state dioxin body burden for the female bluebird
which would result in a NOAEL level of 1000 pg dioxin/g egg.
The research that was cited as ENSR (1989) has also been reported in the 1988 proceedings of
the TAPPI conference (Thiel et al., 1988).
Additional values have been reported for potential effects of dioxin to avian species. Kubiak et
al. (1989) reported on effects to tern eggs from a test site at Green Bay in Michigan in
comparison to tern eggs from the control site at Lake Poygan in Michigan. Verrett (1970; as cited
in Kubiak et al., 1989) reported that 10 to20 pg/g of 2,3,7,8-tetrachlorodibenzo-p-dioxin in chicken
eggs produced embryotoxicity, edema, and deformities. Dose-related increases in cardiovascular
malformations of chick embryos were reported by Cheung et al. (1981; as cited in Kubiak et al.,
1989), observing a 20 percent increase in malformations at a dosing level of 6 pg/g and a
doubling of malformations at 65 pg/g.
The Kubiak study reported a level of 201 pg TCDD-TE/g egg in tern eggs from the control site
at Lake Poygan in Michigan and a level of 2175 pg TCDD-TE/g egg in tern eggs from the test site
at Green Bay in Michigan. Both levels are considerably higher than the results, also reported in
Kubiak et al.(1989), of Cheung et al. (1981) who reported cardiovascular malformations "at a
dosing level of 6 pg/g" for domestic chick embryos. Other effects reported included
subcutaneous edema, crossed beaks, and stunted, malformed legs. Kubiak et al. also report on
unpublished data from Verret that "as little as 10 to 20 pg/g of 2,3,7,8-TCDD in chicken eggs
produced embryotoxicity, edema, and deformities." Additional unpublished data from Verret was
used to develop an LD50 for chicken embryo of 140 pg/g. Kubiak et al. then report that these and
other symptoms are similar to the results reported for the Green Bay site (2175 pg TCDD-TE/g
egg) in their research but not observed at the control site at Lake Poygan. No discussion was
presented by Kubiak et al. as to why domestic fowl appear to be more. sensitive than wild tern
populations sampled in this report. Eisler (1986) noted that domestic chickens were relatively
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sensitive to dioxin, and this observation supports the hypotheseis that domestic fowl may not
represent conditions that are found in wild populations.
The results reported by Thiel et al. (1988) involved both laboratory and field studies. The
laboratory studies also looked for effects similar to those reported by Verret and Cheung et al.,
as cited in Kubiak et al.(1989). That is, the researchers specifically looked for evidence of
subcutaneous edema and ascites formation. These are two of the effects identified by Kubiak
et al.(1989). No subcutaneous edema or ascites formation was detected in the controls or any
of the treatment groups less than, or equal to, 1,000 pg TCDD/g egg. If responses are seen at
the levels reported in the articles cited in Kubiak et al.(1989), then severe reductions in hatching
and fledging success should have been observed both in the Thiel et al. (1988) report and at the
control site of the Kubiak et al. (1989) study. However, no reductions in survival or other effects
were observed when compared to controls.
Both Thiel et al. (1988) and Kubiak et al. (1989) can be used to estimate no effect levels that are
considerably higher (1,000 and 200 pg TCDD-TE/g egg, respectively) than the no effect levels
of Verret and Cheung et al. cited in the Kubiak et al. (1989) study. Kubiak et al. (1989) note that
the effects observed by Verret and by Cheung et al. were observed at the Green Bay site, but
not at the control site at Lake Poygan. Using the no effect level of Thiel et al. (1988) of 1,000 pg
TCDD-TE/g egg would be protective, but use of the more conservative field results of Kubiak et
al. (1989) indicating a no effect level of 200 pg TCDD-TE/g egg would be more conservative and
would result in additional protection. Therefore, the value 200 pg TCDD-TE/g egg was used in
this evaluation.
Dioxin concentration in egg = dioxin per gram of egg (pg dioxin/g egg) x egg weight (g/egg)
= 200 pg dioxin/g egg x 3g/egg = 600 pg dioxin/egg
Dioxin concentration in bird (pg dioxin/bird) = dioxin in egg (pg dioxin/egg)/bird-to-egg
translocation factor [(pg/egg)/(pg/bird)]
= 600 (pg dioxin/egg)/0.048[(pg/egg)/(pg/bird)]
= 12,500 pg dioxin/bird
Dioxin concentration in bird (pg dioxin/kg bird) = dioxin in bird (pg dioxin/bird)/bird body
weight (kg bird)
= 12,500 (pg dioxin/bird)/0.034 (kg bird)
= 367,647 pg dioxin/kg bird = 3.68E-04 mg dioxin/kg bird
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Thus, it is estimated that the female bluebird body burden of 3.68E-04 mg dioxin/kg bird will result
in a NOAEL for bluebird embryonic toxicity of 200 pg dioxin/g egg. This dose response value is
assumed to be protective of other avian species and is applied to the belted kingfisher in this
ecological evaluation.
6.5.2 Exposure Evaluation
Indicator species may be potentially exposed to constituents through air, soil, surface water,
sediments, ground water, and the food chain. The selection of pathways for analysis depends
upon the Site conditions, the biology of the species, and the ecological evaluation methodology.
The potential exposure pathways for the muskrat and the belted kingfisher are described in the
following subsections.
6.5.2.1 Muskrat Exposure Evaluation
Muskrats are semiaquatic rodents that may potentially inhabit the Site. They are a very territorial
species and usually live alone or with their mates (Chapman and Feldhamer, 1982). The area
occupied by a muskrat is dependent upon the size, configuration, and diversity of aquatic habitat;
social pressures; and environmental conditions. Under normal conditions, a muskrat will typically
move to a new area each spring (Chapman and Feldhamer, 1982). In this evaluation, muskrats
are assumed to spend three years of their 4-year lifespan in Fire Pond. This assumes that a one-
year old muskrat migrates to Fire Pond, establishes a lodge, and remains at this location for the
remainder of its lifetime. Once at Fire Pond, the muskrat is assumed not to migrate away from
the Site. This is a conservative exposure scenario for the muskrat, as it is unlikely that a muskrat
will inhabit the same lodge for more than a year (Godin, 1977). The muskrat is assumed to be
potentially exposed to constituents in Fire Pond through water ingestion, inadvertent sediment
ingestion, and ingestion of aquatic plants. Calculation of the potential exposure dose through
these potential exposure pathways is described in detail below.
Water Ingestion
Potential exposure through the ingestion of water is estimated using the following equation:
Lifetime Average Daily Dose (mg/kg-day) = Constituent concentration in water (mg/L) x
Water ingestion rate (Uday) x Oral Absorption Adjustment Factor
(unitless) x Exposure frequency (days exposed/365 days) x Exposure
duration (years/years exposed) / Body weight (kg)
The constituent concentrations in Fire Pond surface water, presented in Table 2-5 of the baseline
risk assessment, are used in this evaluation. In the absence of a published water ingestion rate
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for the muskrat, this parameter was estimated from available mammalian literature. Data from
Robbins (1983) indicate that water turnover rates of wild mammals is a function of body weight.
The water turnover rate for wild mammals weighing approximately 1 kg is approximately 100 mis,
estimated from a figure presented in Robbins (1983). Turnover rates for animals fed water ad
libitum may reflect a level of water intake that is above their minimum needs (Robbins, 1983).
Thus, the ingestion rate for the muskrat is conservatively assumed to be 0.1 liters. Muskrats are
assumed to obtain their entire drinking water requirement from Fire Pond every day for three
years. The average body weight of the muskrat is 1.4 kg (Burt and Grossenheider, 1976).
Absorption Adjustment Factors (AAFs) used in this assessment are the same AAFs as used in
the human health assessment (See Table 4-2).
Plant Ingestion
Muskrats typically consume a diet of aquatic plants such as pondweed, cattails, duckweed, and
water lilies. They may also eat insects, frogs, snails, minnows, and young birds. This
assessment assumes that the muskrat only consumes aquatic plants growing in Fire Pond.
Potential exposure through plant ingestion is calculated using the following equation:
Lifetime Average Daily Dose (mg/kg-day) = Constituent concentration in sediment (mg/kg)
x Root uptake factor x Plant ingestion rate (kg/day) x Oral AAF x Exposure
Frequency (day/ 365 day) x Exposure duration (year/years exposed) /
Body weight (kg)
Constituent concentrations in Fire Pond sediment, presented in Table 2-7, are used in this
assessment. Root uptake factors used in this evaluation are presented in Table 6-7. Muskrats
may consume up to one-third their body weight in food on a daily basis. This evaluation assumes
a body weight of 1.4 kg and a food consumption rate of 0.47 kg per day (1.4 kg + 3). It is
conservatively assumed that the muskrat's diet consists solely of aquatic plants from Fire Pond
and that the muskrat eats these plants at its maximum consumption rate on a daily basis for three
years. Thus, it is likely that the potential effects estimated in the muskrat evaluation will be an
overestimate.
Sediment Ingestion
Muskrats may inadvertently ingest sediment while ingesting aquatic plants and roots and when
building or repairing their lodge in the pond. The following equation is used to estimate potential
exposure to constituents via inadvertent sediment ingestion:
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Lifetime ·Average Daily Dose (mg/kg-day) = Constituent concentration in sediment (mg/kg
sediment) x Sediment ingestion rate (kg sediment/day) x Oral AAF x
Exposure frequency (day/365 days) x Exposure duration (years/years
exposed) / Body weight (kg)
Constituent concentrations in Fire Pond sediment, presented in Table 2-7, are used in this
assessment. No information on sediment ingestion was located for the muskrat. An ingestion
rate was calculated from the assumption that a certain percentage of the total intake of food (on
a dry matter basis) is composed of sediment. This is a practice commonly used for estimating
the soil ingestion rate of large foraging mammals such as sheep, cattle and deer. In this
evaluation, it is assumed that aquatic plants contain a similar amount of moisture as grasses.
On the average, grasses contain approximately 90 percent moisture (Emsinger, 1978). An
inadvertent sediment ingestion rate of three percent of the daily dry weight plant intake is used
in this evaluation. This corresponds to a sediment ingestion rate of approximately 1.41 grams
of sediment per day. Sediment ingestion from Fire Pond is assumed to occur every day for three
years.
6.5.2-2 Belted Kingfisher Exposure Evaluation
The belted kingfisher is assumed to reside in the vicinity of the Morrisville Site throughout its
entire three-year lifespan. The belted kingfisher primarily nests in nearly vertical earth exposures,
such as road cuts, cliffs, gravel pits and sand banks (Cramp et al., 1985). Because the banks
of Fire Pond and Medlin Pond are not appropriate for nesting, the kingfisher is assumed to nest
elsewhere. The foraging range of the belted kingfisher is approximately 8 kilometers (Cramp et
al., 1985). Because the foraging range of the belted kingfisher is relatively large (Cramp et al.,
1985), and because several bodies of water are present in the Morrisville Site area, the belted
kingfisher is conservatively assumed to obtain half of its daily food requirement from Fire Pond
throughout it's 3-year lifespan. Exposure is evaluated at Fire Pond rather than Medlin Pond
because the measured constituent concentrations are greater in Fire Pond than in Medlin Pond.
Thus, the belted kingfisher is assumed to be potentially exposed to constituents in Fire Pond
through fish ingestion. Calculation of the potential exposure through the fish ingestion exposure
pathway is described in detail below.
Pumpkinseed data from Fire Pond were used in the evaluation of potential exposure of kingfisher
to fish in the study area. Largemouth bass data were available for Medlin Pond, but were not
used here. The use of the body burdens found in largemouth bass might be expected to result
in higher exposures for the belted kingfisher than consumption of fish at lower trophic levels.
Examination of Table 2-1 indicates that three largemouth bass fillet composite samples were
collected from Medlin Pond. These were not used in the belted kingfisher analysis because the
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concentrations in fish fillets from Fire Pond were higher, and it was conservatively assumed that
the belted kingfisher was obtaining its food from Fire Pond. The mean concentration of TC DD-TE
from Medlin Pond was 1.19E·03 ug/L while the mean concentration from Fire Pond was 1.81 E-02
ug/L. The use of actual fish concentration data from Fire Pond from pumpkinseed provides a
more conservative estimate of exposure than the use of largemouth bass data from Medlin Pond.
Fish Ingestion
The diet of the kingfisher primarily consists of freshwater and marine fish, aquatic insects, and
occasionally, terrestrial insects and amphibians (Cramp et al., 1985). The following equation is
used to estimate potential constituent exposure from fish ingestion:
Average Daily Dose (mg/day) = Constituent concentration in fish (mg/kg fish) x
Fish ingestion rate (kg fish/day) x Exposure frequency (days/365 days)
x Exposure Duration (years/years exposed)
Fish were sampled from Fire Pond and actual constituent concentrations in fish fillets were
determined. These site-specific data are presented in Table 2·10 and are the constituent
concentrations used in this evaluation. The ingestion rate for the belted kingfisher was not
located in the literature. An ingestion rate for this species was calculated from a regression
equation developed by Nilsson and Nilsson (1976). These authors reported a correlation between
body weight and food consumption in fish-eating birds. A fish consumption rate of 36 grams/day
was calculated from the following equation:
Log F = ·0.293 + 0.850 x Log W
Where,
F = Daily food consumption in grams, and
W = Body weight in grams.
The average body weight of the belted kingfisher is 150 grams (Cramp et al., 1985). The
kingfisher is assumed to ingest its entire daily fish requirement of 36 grams per day from Fire
Pond for 182 days of each year of its 3-year lifespan.
As in other animal species, dioxin is potentially expected to bioconcentrate in the tissue of the
kingfisher. Van den Berg et al. (1987) reported a 2,3,7,8-TCDD bioconcentration factor of 12 in
the bird. ENSR (1989) calculated a biological half-life of 7.22 days for 2,3, 7,8-TCDD in the
bluebird. These parameters are used to obtain estimates of TCDD-TE body burden in the
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kingfisher anhe end of its 3-year lifespan (1095 days). The following equations are used to
calculate the TCDD-TE body burden in the bird:
TCDD-TE In Kingfisher On Day 1095 (mg/kg)= TCDD·TE average daily dose (mg/day) x
TCDD-TE BCF (kg food/kg tissue) x TCDD-TE
build-up (unitless) / Total daily food consumption (kg food/day)
Where,
TCDD-TE build-up= 1 · e·1"'11 22 ''"1"'""''
This equation utilizes first order kinetics to account for TCDD-TE build-up and elimination in the
bird over the 1095-day lifespan.
In this evaluation, the kingfisher is conservatively assumed to obtain half of its diet from Fire Pond
fish throughout its lifetime and will thus, theoretically, have no time to eliminate TCDD-TE from
the body. Therefore, depuration of TC DD-TE body burdens is not expected to occur and is thus
not considered in this evaluation.
6.5.3 Characterization of Potential Riparian Impacts
The potential chronic assumed adverse noncarcinogenic effects are estimated for terrestrial
species in a manner similar to that of the human health hazard indices. A "species-specific dose-
response value" is derived to represent the level of constituent exposure which will have no
adverse effects on a terrestrial receptor. The "estimated potential exposure" for the receptor is
then divided by the species-specific dose-response value to derive a "noncarcinogenic quotient".
Noncarcinogenic Quotient Estimated PotentiBI Exposu/'9
Species-Specific Dose-Response Value
The potential noncarcinogenic quotients can be summed for different constituents and different
pathways to calculate total potential noncarcinogenic quotient for the total estimated exposure of
an indicator species to constituent concentrations at the Site. The total noncarcinogenic quotient
is interpreted using the same criteria as those established by the EPA (1988b) for the toxicity
quotient method. Conclusions are expressed as "no concern" if the total non carcinogenic quotient
is less than 0.1; "possible concern" if the quotient falls within the range of 0.1 and 1 O; and "high
concern" if the quotient is greater than 1 0. The total potential noncarcinogenic quotients
estimated for the muskrat and the belted kingfisher are discussed in the following subsections.
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6.5.3.1 Muskrat Characterization
Exposure to constituents by muskrats inhabiting Fire Pond results in an estimated total potential
noncarcinogenic quotient of 0.11. This quotient, which falls at the extreme lower end of the 0.1
and 1 0 range, and indicates "possible concern". Approximately 87 percent of the total
noncarcinogenic quotient is attributed to the muskrat's potential exposure to PCDD/PCDF in Fire
Pond sediment through ingestion of aquatic plants and sediments.
6.5.3.2 Belted Kingfisher Characterization
The potential noncarcinogenic quotient calculated for the kingfisher eating fish from Fire Pond and
assumed to be bioconcentrating PCDD/PCDF for 1095 consecutive days (daily throughout its
entire 3-year lifespan) is 0.30.
The data gathered for this evaluation were fish fillet concentrations from Fire Pond and Medlin
Pond. It may be more appropriate to evaluate the potential effects on the kingfisher of "whole
body" rather the fillet concentrations. The Integrated Risk Assessment for Dioxins and Furans
from Chlorine Bleaching in Pulp and Paper Mills (U.S. EPA, 1990c) indicates that a factor of two
can be used to adjust from fillet to whole body concentrations of 2,3,7,8-TCDD. This would result
in a potential noncarcinogenic quotient for Fire Pond, based on whole body fish concentrations,
of 0.60 which falls at the lower end of the 0.1 to 10 range and indicates "possible concern".
A corresponding potential noncarcinogenic quotient can be calculated for Medlin Pond based on
the comparison of fish tissue levels from Fire Pond (1.81 E-02 µg/L) and Medlin Pond
(1.19E-03 µg/L). The whole body fish concentration based noncarcinogenic quotient is directly
proportional to the fish concentration, so the resulting quotient for Medlin Pond would be 0.04.
This quotient falls below 0.1 and indicates "no concern".
6.6 Ecological Evaluation Summary
The results of this evaluation show that for the aquatic assessment, the acute toxicity quotients
for Fire Pond indicate "no concern" as defined by EPA. The chronic toxicity quotients for all
constituents except dioxin indicate "no concern", and the chronic quotient for dioxin in Fire Pond
indicates "high concern" as defined by EPA. This indicates that there is a potential for effects on
aquatic organisms from exposures to surface water in Fire Pond. For the aquatic assessment
in Medlin Pond, the calculated acute toxicity quotients were of "no concern" as defined by EPA,
and the calculated chronic toxicity quotients for several constituents were at the low end of the
range of "possible concern" and all others were of "no concern".
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The results of the riparian evaluation show that for muskrats inhabiting Fire Pond, the calculated
quotient was at the lower end of the range indicating "possible concern". For belted kingfisher
inhabiting the Site area, the calculated quotient was also at the lower end of the range indicating
"possible concern".
The majority of potential assumed risk to ecological receptors estimated in this assessment is
attributable to dioxin in surface water. Dioxin was detected in three surface water bodies at this
Site, Fire Pond, Medlin Pond, and Western Ditch. Because both Fire Pond and Medlin Pond can
sustain aquatic and/or riparian life, the exposure of ecological receptors to these water bodies
was evaluated in this assessment. As shown, the potential exposure of aquatic receptors to Fire
Pond surface water may pose a risk of "high concern", and the potential exposure of aquatic
receptors to Medlin Pond surface water may pose a risk of "possible concern". The results of the
assessment also show that the assumed exposure of riparian receptors to the Ponds studied is
unlikely to result in adverse effects.
The majority of potential risk to ecological receptors from assumed exposure to the surface water
in Fire Pond and Medlin Pond is attributable to dioxin. Although dioxin was also detected in the
Western Ditch, dioxin in this Ditch is assumed not to pose an unexceptable potential ecological
risk for at least the following three reasons. First, the Western Ditch is not a viable aquatic
habitat because it only contains water on an intermittent basis and does not support an aquatic
community that could provide food, and thus potential exposure to constituents for the aquatic
receptors evaluated in this assessment, on a regular basis. Similarly, if any potential riparian
exposures were to occur to the ecological receptors evaluated in this assessment, they would be
lower than those estimated for Fire Pond because the concentrations of dioxin in the Western
Ditch are lower than those in Fire Pond. Because the risks associated with assumed riparian
exposures to Fire Pond estimated in this assessment were of no concern, any assumed exposure
to the Western Ditch would also be of no concern. Finally, the receptors selected for evaluation
in this assessment were chosen specifically because they were assumed to represent the most
sensitive ecological receptors potentially exposed to Site-related constituents. Specifically, these
receptors are potentially exposed to biomagnified levels of constituents while other receptors
would be potentially exposed to constituents primarily through direct contact with constituents in
environmental media. Thus, even if different receptors were exposed to the Western Ditch, the
potential ecological risks to these potential receptors are assumed to be less than assumed for
the receptors used in this ecological evaluation_.
In addition to the surface water, the pond sediments pose a potential concern for ecological
impacts based on their potential to serve as a source of constituents to the surface water.
Actions, such as burial, which would render the constituents in the sediment biologically
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unavailable a:nd prohibit contact with surface water would greatly reduce any potential ecological
risks associated with constituents in the sediment.
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conservative approach that substantially overestimates the "average" level of potential risk posed
by a site.
The risk assessment approach used here employed upper 95% bounds or maximums for most
exposure and toxicity assumptions. Thus it produces estimates of potential risk two to three
orders of magnitude greater than the risk experienced by the average member of the potentially
exposed populations.
7.1.5 Summary of Sources of Uncertainty in the Human Health Evaluation
The large number of assumptions made in the risk characterization could potentially introduce a
great deal of uncertainty. While this could potentially lead to underestimates of potential risk, the
use of numerous upper-bound assumptions guarantees that overestimates of potential risks will
result. As discussed elsewhere in the report, any one person's potential exposure and
subsequent assumed risk are influenced by all the parameters mentioned in the text and will vary
on a case-by-case basis. Despite inevitable uncertainties associated with the steps used to
derive potential risks, the use of numerous health-protective assumptions will most likely lead to
an overestimate of potential risks from the Site.
7.2 Uncertainties Associated with the Ecological Evaluation
A large number of assumptions that can lead to uncertainty are made in the evaluation of the
potential for assumed adverse ecological effects at the Morrisville Site. Given the conservative
assumptions set forth in the guidance documents, the results of this evaluation may overestimate
the potential for adverse ecological effects at this Site. A qualitative discussion of the major
sources of uncertainty associated with the ecological evaluation is presented below.
Extrapolation of the potential for community, population, or ecosystem effects from the
examination of one or more indicator species is a major source of uncertainty for both the aquatic
and terrestrial analyses. The underlying assumption is that potential effects on one species are
representative of effects on the particular ecosystem being investigated. For this assessment,
bluegills were chosen to represent potential effects on aquatic ecosystems, muskrats were chosen
to represent potential effects on mammalian organisms in terrestrial ecosystems, and belted
kingfishers were chosen to represent potential effects on avian species in terrestrial ecosystems.
Each of these choices represents a potential source of. uncertainty. It is difficult to predict how
an adverse effect on an individual organism would affect the ecosystem as a whole. U.S. EPA
( 1989a) states that "concentrations that are acutely toxic to single species are usually not much
greater than concentrations that are toxic at the ecosystem level. Whereas, concentrations that
are toxic in chronic single species are, in most cases, overprotective of ecosystems." This
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8.2 Ecolo·gical Evaluation Summary
The ecological evaluation assessed aquatic and terrestrial (mammalian and avian) receptors,
focusing on three indicator species: bluegills, muskrat, and belted kingfisher. The potential for
adverse effects to these species was quantitatively evaluated by the quotient method (U.S. EPA,
1988b; ORNL, 1986). The calculated quotient is classified by EPA as being of "no concern" if
less than 0.1, of "possible concern" if between 0.1 and 10, and of "high concern" if greater than
10 (U.S. EPA, 1988b). For bluegills in both Fire Pond and Medlin Pond, the calculated acute
toxicity quotients indicate "no concern". For Fire Pond, the calculated chronic toxicity quotient for
all constituents except dioxin, indicates "no concern". The chronic toxicity quotient for dioxin in
Fire Pond indicates "high concern" as defined by EPA. This indicates that there is a potential for
effects on aquatic organisms from exposures to surface water in Fire Pond, which indicates that
remediation of surface water in Fire Pond may be appropriate. For bluegills in Medlin Pond,
calculated chronic toxicity quotients for several constituents were at the very low end of the range
of "possible concern" and all others were "no concern". These quotients were also calculated
using EPA-prescribed screening values. Due to the uncertainty associated with the screening
values used to evaluate the potential for adverse effects from exposure to surface water, it may
also be appropriate to remediate surface water in Medlin Pond.
For muskrats inhabiting Fire Pond, the calculated quotient was at the extreme lower end of the
range indicating "possible concern". For belted kingfisher inhabiting the Site area, the calculated
quotient was also at the lower end of the range indicating "possible concern". The majority of risk
for ecological receptors in associated with potential exposure to surface water in Fire Pond. As
discussed in Section 6, if the belted Kingfisher was assumed to eat fish from Medlin Pond instead
of Fire Pond, the noncarcinogenic quotient would be 0.04, which indicates "no concern".
8.3 Baseline Risk Assessment Summary
Thus, the results of the baseline risk assessment indicate that remediation is likely required for
only surface soil in Area C, surface water in Fire Pond, surface water in Medlin Pond and on-Site
ground water under the Eastern and Former Lagoon Areas, and that remediation is likely not
necessary for other areas and environmental media. Section 9.0 presents a comparison of risk-
based target clean-up levels with Federal and State ARARs and other relevant guidelines. As
described in Section 9.0, additional areas may require remediation based on factors other than
estimated assumed risks to human or ecological receptors.
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Hypothetical ·receptors were evaluated for each of the two potential future Site use conditions
evaluated in the baseline risk assessment. On-Site Workers and Local Off-Site Residents were
evaluated for the commercial/industrial Site use scenario. The Local Off-Site Resident evaluation
includes the potential exposures of teenagers trespassing on the Site. At the request of EPA,
hypothetical On-Site Resident receptors were evaluated for potential future residential use of the
Site. Appendix G presents the RBTCLs derived for pentachlorophenol and PCDD/PCDF for each
of these receptors.
9.1.2 Ecological Evaluation
The ecological evaluation presented in Section 6.0 and Appendix G of the baseline risk
assessment showed that potential assumed risks to ecological receptors for all constituents,
except PCDD/PCDF in Fire Pond surface water, were at the level of "no concern" as defined by
EPA. This indicates no need for remediation of surface water in Fire Pond or Medlin Pond for
these constituents. The assumed potential exposure of aquatic species to PCDD/PCDF in Fire
Pond surface water was evaluated in the baseline risk assessment using a screening toxicity
value required by EPA. The results of this evaluation indicate that potential aquatic exposures
to PCDD/PCDF in Fire Pond are of "high concern" as defined by EPA. This indicates that there
is a potential for effects on aquatic organisms from exposures to surface water in Fire Pond,
which indicates that remediation of surface water in Fire Pond may be appropriate. Due to the
uncertainty associated with the screening values used to evaluate the potential for adverse effects
from exposure to surface water, it may also be appropriate to remediate surface water in Medlin
Pond to protect aquatic organisms.
Specific methodologies exist for determining RBTCLs for potential human exposures based on
allowable risk levels. Similar specific guidance is not available for aquatic receptors.
9.2 Comparison of RBTCLs and ARARs
When remediation goals for media or areas of the Site are considered, the RBTCLs and all
applicable standards can be compared in order to determine the most reasonable and appropriate
remediation measures to pursue. The relevant ARARs identified for the constituents of interest
in this evaluation are North Carolina standards and federal MCLs for pentachlorophenol and
2,3, 7,8-TCDD, and the North Carolina MCL for 2-chlorophenol. Soil target clean-up levels for the
protection of ground water have also been derived for these two constituents (Keystone, 1992).
This section presents a summary of the comparison of maximum measured constituent
concentrations, as directed by U.S. EPA Region IV in consideration of potential hot spot exposure
under future residential scenarios, in various media with RBTCLs derived for the hypothetical
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receptors, State of North Carolina and federal ARARs, and soil clean-up levels for the protection
of ground water. A detailed discussion of this comparison is presented in Appendix G.
Comparison to average constituent concentrations is also scientifically and statistically appropriate
for some exposure scenarios, but is not presented in this document at the request of U.S. EPA
Region IV.
Existing maximum concentrations of constituents, as directed by EPA, were compared with
RBTCLs, soil target clean-up levels for the protection of ground water, and State and federal
ARARs. The results of the ecological evaluation and the results of the human exposure analysis
indicate that existing maximum constituent concentrations exceeded RBTCLs (at the 1 E-05 risk
level), ARARs, or soil target clean-up levels for the protection of ground water, only in the
following media:
• Surface Soil in Area C
• Subsurface Soil in Area C
• Surface Water in Fire Pond
• Surface Water in Medlin Pond
• Fish in Fire Pond
• Ground Water in the Former Lagoon Area
• Ground Water in the Eastern Area
In Area C surface soil, existing maximum concentrations of pentachlorophenol exceeded RBTCLs
at the 1 E-06 risk level for local off-Site residents, and RBTCLs at the 1 E-05 risk level for on-Site
workers in the commercial/industrial Site use scenarios. In Area C surface soil, existing maximum
concentrations of PCDD/PCDF exceeded the RBTCLs at the 1 E-04 risk level for the local off-Site
resident and the on-Site worker in the commercial/industrial Site use scenarios. In Area B surface
soil, the maximum measured concentration of PCDD/PCDF exceeded the RBTCL at the 1 E-06
risk level for the on-Site worker in the commercial/industrial Site use scenarios.
In the residential Site use scenarios, the maximum concentration of pentachlorophenol in Area
C surface soil exceeded the RBTCL at the 1 E-04 risk level for the hypothetical on-Site resident.
The maximum concentrations of PCDD/PCDF in Area Band Area C surface soil were exceeded
by the RBTCLs at the 1 E-05 and 1 E-04 risk levels, respectively, for the hypothetical on-Site
resident.
In addition, existing maximum concentrations of pentachlorophenol and PCDD/PCDF exceeded
the soil target clean-up levels for the protection of ground water.
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In Area C subsurface soil, existing maximum pentachlorophenol concentrations exceeded the soil
target clean-up level for the protection of ground water. Maximum concentrations of PCDD/PCDF
in Area C subsurface soil exceeded the RBTCLs at the 1 E-06 risk level for the local off-Site
resident and the on-Site worker in the commercial/industrial Site use scenarios. Maximum
concentrations of pentachlorophenol and PCDD/PCDF in subsurface soil in Area C exceeded the
RBTCLs at the 1 E-06 risk level for the hypothetical on-Site resident in the future residential Site
use scenarios.
In the commercial/industrial Site use scenarios, the maximum concentration of PCDD/PCDF in
Fire Pond surface water exceeded the RBTCL for the local off-Site resident at the 1 E-06 risk
level. In the future residential Site use scenarios, the maximum concentration of PCDD/PCDF
in Fire Pond exceeded the RBTCL for the hypothetical on-Site resident at the 1 E-04 risk level.
In the ecological evaluation, surface water in Fire Pond and surface water in Medlin Pond may
require remediation for the protection of aquatic species.
In sediment in the discharge stream from Fire Pond, maximum PCDD/PCDF concentrations
exceeded the RBTCL for the local off-Site resident at the 1 E-06 risk level. In Fire Pond, the
maximum sediment concentration exceeded the RBTCL for the hypothetical on-Site resident at
the 1 E-06 risk level.
In ground water in the Eastern Area, maximum pentachlorophenol concentrations exceeded
RBTCLs at the 1 E-05 risk level. In Former Lagoon Area ground water, maximum
pentachlorophenol concentrations exceeded RBTCLs at the 1 E-04 risk level. Maximum
pentachlorophenol concentrations in both areas exceeded the MCL for pentachlorophenol. In
ground water in the Former Lagoon Area and Eastern Area, maximum concentrations of
PCDD/PCDF exceeded RBTCLs at the 1 E-04 risk level and also exceeded the proposed MCL
for PCDD/PCDF.
In Eastern Area ground water, the maximum concentration of 2-chlorophenol exceeded the State
of North Carolina MCL for this constituent. In Off-Site Area ground water, one estimated sample
( designated by the "J" qualifier in the laboratory results) exceeded the State MCL for 2-
chlorophenol. RBTCLs for 2-chlorophenol in ground water were not calculated here because the
focus of this report is on the two constituents contributing nearly 100 percent of the assumed risk,
pentachlorophenol and dioxin. Because the maximum detected concentrations of 2-chlorophenol
in Eastern Area ground water exceeded the State ARAR for this constituent, remediation may be
required in this area. Because the only detected value for 2-chlorophenol in Off-Site Area
groundwater is an "estimated" value, and because the sampling location in which this value was
estimated is located within the bounds of the area that will be impacted by pumping of Site
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ground water; Off-Site Area groundwater is not identified as an area that may require remediation.
Any remediation of the on-site plume of constituents will also address any constituents in off-Site
Area ground water. Additional sampling of off-site wells will be conducted during the remedial
phase to confirm the recommendation that off-site Area ground water does not require a separate
remediation effort.
Maximum concentrations of PCDD/PCDF in fish tissue from Fire Pond exceeded RBTCLs at the
1 E-06 risk level for both the local off-Site resident and the hypothetical on-Site resident. In Medlin
Pond, maximum concentrations of PCDD/PCDF in fish tissue exceeded RBTCLs only at the 1 E-
06 risk level for the local off-Site resident.
9.3 Summary and Recommendations
This Section has reviewed the clean-up levels evaluation presented in Appendix G of the baseline
risk assessment. The human health RBTCLs were determined using the potential assumed
carcinogenic risks estimated in the baseline risk assessment, which was conducted following EPA
guidance and in accordance with standard risk assessment methodology. Parallel analyses for
ecological receptors suggest that remedial action may be necessary for surface water in Fire
Pond and in Medlin Pond.
Human health RBTCLs were derived for potential future receptors assuming two different potential
future Site use conditions. At this time, no decision has been made regarding the future use of
the Site. However, it is unlikely that the Site will become residential in the future because recent
development in the area has been commercial/industrial, and the Site is currently occupied with
industrial enterprises. In addition, institutional controls, such as placing a land-use restriction on
the deed for the property preventing residential use, can and will be introduced by Beazer to
assure that its portion of the Site remains commercial/industrial.
As described in Section 9.2 and in Appendix G, on-Site surface and subsurface soil in Area C,
surface water in Fire Pond, surface water in Medlin Pond, fish in Fire Pond, and on-Site ground
water in the Former Lagoon, and Eastern Areas may require remediation. Table 9-1 presents a
summary of the areas with the corresponding existing maximum constituent concentrations,
RBTCLs, ARARs and soil target clean-up levels for protection of ground water evaluated in detail
in Appendix G.
Table 9-1 also shows the clean-up goals recommended by Beazer East, Inc. for the various
media identified here. For surface and subsurface soil in Area C, the recommended clean-up
goals are the soil target clean-up levels for the protection of ground water. For Fire Pond surface
water and fish, the recommended clean-up goals are the human health RBTCLs at the 1 E-05 risk
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level derived.in Appendix G. For ground water, the recommended clean-up goals are the federal
or state ARARs, or MCLs.
The recommended soil clean-up goals at this Site are the soil target clean-up levels for the
protection of ground water: 95 ppm for pentachlorophenol, and 0.007 ppm for PCDD/PCDF.
Upon review of the available surface soil data in Area C, it is apparent that remediation of
pentachlorophenol to it's clean-up goal for the protection of ground water will also achieve the
clean-up goal for PCDD/PCDF. This is illustrated in Table 9-2. The measured pentachlorophenol
concentrations in Area C surface soil are ranked in descending order and are compared with the
pentachlorophenol soil target clean-up level for the protection of ground water. Four samples in
this area exceed the soil target clean-up level for the protection of ground water. Based upon the
historical operations of the Koppers facility on the Site, it is likely that the occurrence and
concentration of pentachlorophenol and PCDD/PCDF in surface soils are co-located. This co-
location of constituents is shown on Table 9-2. Therefore, when these four areas are remediated,
the samples with concentrations in excess of the PCDD/PCDF soil target clean-up level for the
protection of ground water are also remediated. This remediation strategy will be investigated
further in the pre-design activities for the Remedial Design Scope of Work.
As a result of this analysis, it is apparent that treating the remediation of pentachlorophenol and
PCDD/PCDF separately is unnecessary. Focussing the remediation strategy on remediating soils
in Area C such that 95 ppm is not exceeded for pentachlorophenol, will also result in achievement
of the soil target clean-up level for the protection of ground water for PCDD/PCDF. This proposed
remediation strategy will be confirmed during the remedial design study at this Site.
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REFERENCES (Continued)
U.S. EPA. 1990b. Drinking Water Regulations and Health Advisories. Office of Drinking Water.
U.S. EPA, November 1990.
U.S. EPA. 1990c. Integrated Risk Assessment for Dioxins and Furans from Chlorine Bleaching
in Pulp and Paper Mills. Office of Pesticides and Toxic Substances, Washington, D.C.
EPA/560/5-90-011.
U.S. EPA. 1991 a. Integrated Risk Information System (IRIS). Environmental Criteria and
Assessment Office, Cincinnati, OH.
U.S. EPA. 1991 b. Supplemental Region IV Risk Assessment Guidance. U.S. EPA, Region IV,
Atlanta, GA.
U.S. EPA. 1991 c. 304(a) Screening Values and Related Information for Toxic Pollutants.
Screening List. Water Management Division, Office of Water Quality Standards. U.S. EPA
Region IV. Atlanta, GA.
U.S. EPA. 1992. Region IV Waste Management Division Screening Values for Hazardous
Waste Sites. Version Dated 1/27/92.
Van den Berg, M., F. Blank, C. Heeremans, H. Wagenaar and K. Olie. 1987. Presence of
Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fish-catching birds
and fish from the Netherlands. Arch. Environ. Contam. Texico/. 16:149-158.
Versar, Inc., 1979. Water-Related Environmental Fate of 129 Priority Pollutants. Vol. 1 and 2,
U.S. Environmental Protection Agency, Washington, D.C., EPA 440/4-79-029.
Verschueren, K. 1977. Handbook of environmental data on organic chemicals. Van
Nostrand/Reinhold Co., New York. p. 659.
Wipf, H., E. Hornberger, N. Neuner, U. Ranalder, W. Vetter, and J. Vuilleumier. 1982. TCDD
Levels in Soil and Plant Samples from the Seveso Area. (As cited in Hutzinger et al. 1982).
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mg/kg. The·RBTCL.s tor pentachlorophenol are less than this concentration. If chronic RBTCL.s
had been higher, it would need to have been limited at the concentration protective of assumed
potential sub-chronic effects.
As discussed in Appendix E, at the reques\ of U.S. EPA Region IV, the calculations used to
estimate potential assumed risks that included degradation factors were edited to remove these
factors from the main text of the final report because no site-specific data confirming the
degradation of constituents in various media is available. The main text of this report shows only
the results from the evaluation that assumes no degradation will occur. These results are also
discussed in this Appendix. Because there is evidence in the literature that supports the
degradation of pentachlorophenol and dioxin, soil and sediment calculations including the
assumption of degradation are also included in this Appendix. As described above, two sets of
degradation rates were used in the derivation of RBTCLs for pentachlorophenol, 60 days (as was
used in the first drafts of the report and is summarized in Appendix E), and 1 year (based on a
more detailed literature search on the degradation of pentachlorophenol). • U.S. EPA Region IV
has not approved of the application of any degradation rates found in the literature, yet if
literature-derived degradation rates are to be used, Region IV has reported a preference for the
1 year half-life for pentachlorophenol in surface soils, and not 60 days as was first used in this
baseline risk assessment. If the half-life for pentachlorophenol is assumed to be 1 year, the
potential assumed risks estimated in Appendix E would have been slightly higher than those
presented (which are based on a hall-life of 60 days). Therefore, three sets of RBTCL.s were
derived for pentachlorophenol for each relevant receptor, RBTCL.s derived assuming no
degradation occurs, RBTCL.s using degradation rates used in the first drafts of the baseline risk
assessment, and RBTCL.s using alternate degradation rates taken from the literature and
summarized here. Two sets of RBTCL.s were derived for dioxin for each relevant receptor,
RBTCL.s derived assuming no degradation occurs, and RBTCL.s using degradation rates used in
the first drafts of the baseline risk assessment. The recommendations for potential remediation
at the Site (see Section G.5) were based on RBTCLs assuming degradation does not occur, as
requested by EPA.
Constituent concentrations in surface water, ground water and fish were not adjusted for
degradation in the baseline risk assessment, nor in this clean-up levels evaluation, because
constituent concentrations need to meet existing standards in surface water and ground water,
and no information was available in the scientific literature to thoroughly evaluate degradation of
the constituents of interest in fish.
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G.1.2: Application of RBTCLs
The potential assumed risks estimated by the baseline risk assessment report are based upon
long-term or chronic exposures. Two different kinds of long term exposure could occur: those
that involve a random pattern of contact with the exposure medium, and those that involve a non-
random pattern of contact with the exposure medium. Because constituent concentrations vary
across environmental media, the type of potential contact (i.e. random or non-random) will affect
the average constituent concentration to which a receptor would be exposed over the long term.
For example, in surface soil, measured concentrations of some of the constituents of interest ai
this Site range from samples in which the constituent was not detected, to samples in which the
constituent was detected at various concentrations. Certain exposure scenarios assume that the
receptor is equally likely to contact each of these concentrations over the exposure period, this
kind of potential exposure is assumed to be "random". Examples of this type of potential
exposure are the trespasser receptor and the on-Site worker receptor. Each of these receptors
is assumed to contact constituents in surface soil across the Site over a long period of time.
The repeated random potential contact with constituent concentrations over the exposure period
assumed by certain scenarios in the risk assessment effectively averages the constituent
concentration a hypothetical person is exposed to over that period. Thus, over the duration of
hypothetical exposure, a person will be exposed to the average constituent concentration, rather
than the maximum or some upper or lower bound concentration. Indeed, as the variance in
constituent concentrations increases, the probability of a person being exposed to an upper bound
constituent concentration becomes vanishing small. This situation is illustrated by Figure G-2
which was developed to illustrate the central limit theorem. The basic principle of this theorem
is that regardless of how skewed the original distribution is (the top of Figure G-2), the distribution
of the means of several sets of samples will be closer to a normal distribution with a most
frequent result approaching the arithmetic average of the original distribution (center of Figure G-
2). When the number of samples in a set is very large, the distribution of means becomes
normally distributed, or centered around the arithmetic average (bottom of Figure G-2). This
phenomenon should be accounted for when applying RBTCLs to determine site remediation
requirements. In particular, because of this phenomenon, it is the average concentration of a
constituent in an area of the site that needs to be equal to the RBTCL or other clean-up goals
based on potential assumed long term random exposures.
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risk, recommendations for remediation may be made based on ARARs or other factors such as
soil clean-up levels for the protection of ground water. In addition, the NCP seeks to require
protection of ground water to allow for its maximum beneficial use. Thus, although constituent
concentrations may not exceed RBTCLs, remediation of ground water to MCLs (i.e. to levels
suitable for residential drinking water purposes) may be required.
No constituent concentrations in Western Area ground water exceed RBTCLs, indicating that
remediation of ground water in this area would not be necessary based on RBTCLs.
G.2.3.6 Fish Sample Results
Pentachlorophenol was not detected in fish tissue samples in any pond of interest. For fish fillet
samples from Fire Pond, the maximum concentrations of PCDD/PCDFs are below the RBTCL at
the 1 E-4 risk level. For fish fillet samples from Fire Pond, the maximum concentrations of
PCDD/PCDF exceed the RBTCLs at the 1 E-5 and 1 E-6 risk levels, indicating that, if the Site were
to become residential, which is considered unlikely, a remedial measure restricting use of fish
from Fire Pond may be needed.
G.3 Ecological RBTCLs
The previous sections have described the derivation of human health based RBTCLs. This
section presents the procedure to derive ecologically based RBTCLs. Section G.3.1 summarizes
the methodology and results of the ecological risk assessment for the Site. Justification for not
deriving ecological RBTCLs is presented in Section G.3.2.
G.3.1 Review of the Ecological Risk Assessment
The ecological risk assessment was conducted following EPA guidance documents: Risk
Assessment Guidance for Superfund: Volume II, Environmental Evaluation Manual (U.S. EPA,
1989d), Recommendations for and Documentation of Biological Values for Use in Risk
Assessment (U.S. EPA, 1988a); Quality Criteria for Water, 1986 (U.S. EPA, 1986); Review of
Ecological Risk Assessment Methods (U.S. _EPA, 1988b); and Ecological Assessment at
Hazardous Waste Sites (U.S. EPA, 1989a).
The ecological evaluation includes a habitat characterization, a review of indicator species, a
qualitative evaluation of terrestrial species, and a quantitative evaluation of both aquatic and
riparian species. The methods used to derive potential assumed hazard quotients for aquatic and
riparian species are described below.
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. G.3.1.1 Aquatic Evaluation
The evaluation of potential assumed exposure of aquatic species to constituents was performed using the toxicity quotient method prescribed by EPA (U.S. EPA, 1988b, ORNL, 1986). This method involves the derivation of a toxicity quotient which is the result of a comparison of surface water constituent concentrations with "benchmark concentrations" for potential assumed toxicological effects. Therefore, all constituents of interest evaluated in the risk assessment are reported here. Acute and chronic noncarcinogenic benchmark concentrations were used to evaluate both potential assumed acute and potential assumed chronic exposures. The benchmark concentrations used in the risk assessment are "screening" values provided by EPA Region IV. Toxicity quotients are classified by EPA as being of "no concern" if less than 0.1, of "possible concern" if between 0.1 and 10, and of "high concern" if greater than 10 (U.S. EPA, 1988b).
The acute toxicity quotients for each of the constituents in Fire Pond and Medlin Pond were all less than 0.01 (Table G-6), and fall in the range of "no concern" (U.S. EPA, 1988b). The results of the chronic hazard screening evaluation for Fire Pond (Table G-7) indicate that TCDD may pose "high concern" (toxicity quotient= 17) for aquatic species according to the EPA classification criteria (U.S. EPA, 1988b). The results of the chronic hazard screening evaluation for Medlin Pond (Table G-7) indicate that TCDD, 2,4,6-trichlorophenol, 2,4-dinitrophenol, 2,3,5,6-tetrachlorophenol, and 2-methyl-4,6-dinitrophenol may pose "possible concern" for aquatic species. Note that each of the constituents in Medlin Pond that fall within EPA's range of "possible concern" are at the extreme low end of this range except for TCDD-TE. This indicates that surface water in Fire Pond and surface water in Medlin Pond may require remediation to protect aquatic organisms.
G.3.1.2 Riparian Evaluation
The evaluation of riparian species at the Site follows a method similar to that used to estimate potential assumed risks to human health. This method involves the application of dose-response criteria and a series of exposure assumptions to a constituent concentration to derive a hazard quotient for a given receptor. The ecological receptors evaluated in the risk assessment are muskrat and belted kingfisher. The muskrat and belted kingfisher were assumed to potentially be exposed to constituents detected in Fire Pond.
The hazard quotient is calculated using the following equation:
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Hazard Quotient=Estimated Assumed Potential Exposure(Dose-ResponseValue
where: the "estimated potential assumed exposure" is derived from a series of assumptions about
the potential assumed exposure of the receptor to constituents in Fire Pond; and the "dose-
response value" is a species-specific value.
The evaluation indicates that the muskrat's total potential assumed hazard quotient is 0.1. This
is at the very bottom of the EPA's range of "possible concern" (0.1 to 10.0), and represents the
sum of all constituent-specific, potential assumed hazard quotients for the muskrat. The results
of the kingfisher evaluation show that the potential assumed exposure of the kingfisher to TCDD-
TEs leads to an potential assumed hazard quotient of 0.6. This is also at the low end of the
"possible concern" range (0.1 -10.0).
G.3.2 Ecological RBTCLs
The method described in Section G.1 of this evaluation for deriving human health RBTCLs could
also be used to derive ecological RBTCLs; however, because no specific methodologies exist for
determining clean-up levels for ecological receptors, no ecological RBTCLs were derived.
In addition, although surface water in Fire Pond and Medlin Pond were identified as areas that
may require remediation based on the results of the aquatic evaluation of TCDD-TE in surface
water, the aquatic screening values are not intended for use in the derivation of clean-up levels
(U.S. EPA, 1992). Thus, no ecological RBTCLs are derived from the results of the aquatic
evaluation presented in the risk assessment. However, a further comparison with other,
scientifically defensible, benchmark concentrations was made based on the results of the
comparison with Region IV screening values. Chronic benchmark values were derived for 2,4,6-
trichlorophenol, 2,4-dinitrophenol, 2,3,5,6-tetrachlorophenol, 2-methyl-4,6-dinitrophenol, and
2,3,7,8-TCDD for constituents in Medlin Pond and for 2,3,7,8-TCDD in Fire Pond. The derivation
of these benchmarks, and the resulting chronic toxicity quotients, is described below.
2.4,6-Trichlorophenol
The Ambient Water Quality Criteria for Chlorinated Phenols (U.S.EPA, 1980a) indicates that the
only freshwater chronic data found were for 2,4,6-trichlorophenol. The species mean acute value
for an early life cycle stage test with fathead minnow was 720 µg/1. EPA Region IV recommends
the application of a safety factor of ten when the data concerning the acute toxicity of a
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compound are limited. Applying th_is safety factor to limited chronic toxicity data would result in •• a chronic effects benchmark concentration of 72 µgn for Medlin Pond and a chronic toxicity quotient of 0.008. This quotient falls in the range of "no concern" as defined by EPA (U.S. EPA, I 1988b), and thus, no clean-up levels will be calculated for 2,4,6-trichlorophenol.
2,4-Dinitrophenol
The Ambient Water Quality Criteria for Nitrophenols (U.S.EPA, 1980e) indicates that no freshwater chronic data were found for nitrophenols. The document indicates that toxicity to one species of algae may occur at concentrations as low as 150 µgn. EPA Region IV recommends the application of a safety factor of ten when the data concerning the acute toxicity of a compound are limited. Applying this safety factor to limited chronic toxicity data would result in a chronic ettects benchmark concentration of 15 µg/ for Medlin Pond and a chronic toxicity quotient of 0.05. This quotient falls in the range of "no concern" as defined by EPA (ref), and thus, no clean-up levels will be calculated for 2,4-dinitrophenol.
2,3,5,6-Tetrachlorophenol
The Ambient Water Quality Criteria for Chlorinated Phenols (U.S.EPA, 1980a) indicates that no freshwater chronic data found were for tetrachlorophenols. Three species mean acute values were presented. The species mean acute values for 2,3,5,6-tetrachlorophenol with Daphnia magna and bluegill (lepomis macrochirus) were 570 µg/I and 170 µg/I, respectively. An additional acute value of 140 µgn for the effects of 2,3,4,6-tetrachlorophenol with bluegill was reported. EPA Region IV recommends the application of a safety factor of ten when the data concerning the acute toxicity of a compound are limited and the application of an additional safety factor of ten when extrapolating from acute to chronic effects. This would result in a chronic effects benchmark concentration of 14 µgn for Medlin Pond based on 2,3,4,6-tetrachlorophenol and a chronic toxicity quotient of 0.14. This quotient falls at the extreme low end of the range of "possible concern" as defined by EPA (1988b) and thus, no clean-up levels will be calculated for 2,3,5,6-tetrachlorophenol.
2-Methyl-416-dinitrophenol
The Ambient Water Quality Criteria for Nitrophenols (U.S.EPA, 1980e) indicates that no freshwater chronic data were found for nitrophenols. The document indicates that toxicity to one species of algae may occur at concentrations of 2-methyl-4,6-dinitrophenol as low as 150 µgn. EPA Region IV recommends the application of a safety factor of ten when the data concerning the acute toxicity of a compound are limited. Applying this safety factor to limited chronic toxicity data would result in a chronic effects benchmark concentration of 15 µgn for Medlin Pond and a chronic toxicity quotient of 0.04. This quotient falls in the range of "no concern" as defined by EPA (1988b). and thus, no clean-up levels will be calculated for 2-methyl-4,6-dinitrophenol.
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2,3,7,8-TCDD
Two major sources examined for toxicity information on 2,3,7,8-TCDD. The Fish and Wildlife
service "conservatively estimated that water levels of 2,3,7,8-TCDD should not exceed 0.01 ng/I"
(Eisler, 1986). Some of the data upon which this "conservative estimate" is based comes from
24 hour exposures of guppies. A chronic value was also reported from a 96 hour test on
Northern pike embryos. The Ambient Water Quality Criteria for 2,3,7,8-TCDD (U.S. EPA, 1984)
indicates that insufficient freshwater chronic data were available to calculate a chronic criterion.
The EPA also reviewed the information used as the basis of the Fish and Wildlife Service report
including the 96 hour test on Northern pike embryos that indicated a "slight reduction in growth
up to 21 days." The criteria document concluded that "the available information indicates that
acute values for some freshwater animal species are greater than 1.0 µg/I; some chronic values
are less than 0.1 µg/I, and the chronic value for rainbow trout is less than 0.001 µg/I" (U.S.EPA.
1984). EPA Region IV recommends the application of a safety factor of ten when the data
concerning the acute toxicity of a compound are limited. Applying this safety factor to the limited
chronic toxicity data reported for rainbow trout would result in a chronic effects benchmark
concentration of 0.0001 µg/I for Fire Pond and Medlin Pond and chronic toxicity quotients of 1.65
and 0.12, respectively. These quotients fall at the low end of the range of "possible concern" as
defined by EPA (U.S. EPA, 1988b). Specific methodologies exist for determining clean-up levels
for human health based on allowable risk levels. Similar specific guidance is not available for
aquatic receptors, thus, no RBTCL.s are derived for aquatic receptors.
The muskrat evaluation indicated a total potential assumed hazard quotient equal to 0.1. Each
constituent-specific hazard quotient is less than 0.1, or of "no concern". Because the estimated
exposure to each constituent results in an potential assumed hazard quotient considered to be
of "no concern", no RBTCL.s were calculated for the muskrat. Similarty, the potential assumed
hazard quotient for the kingfisher for TCDD-TE is 0.6 which is at the low end of the range of
"possible concern". Thus, no ecological RBTCL.s were derived for the kingfisher. The results of
both of these evaluations indicate that remediation is not necessary to protect riparian ecological
receptors.
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G.4 Comparison of ARARs and RBTCLs
This section presents a comparison of existing constituent concentrations in various media with RBTCLs derived in Section G.2, State of North Carolina and federal ARA Rs, and soil target clean-up levels derived for the protection of ground water. When remediation goals for media or areas of the Site are considered, the RBTCLs and all applicable standards can be compared in order to detennine the most reasonable and appropriate remediation measures to pursue.
The relevant ARARs identified for the constituents of interest in this document are North Carolina standards and federal MCLs for pentachlorophenol and 2,3,7,8-TCDD, and the North Carolina MCL for 2-chlorophenol. Soil target clean-up levels for the protection of ground water have also been derived for pentachlorophenol and 2,3,7,8-TCDD (KER, 1992a).
Tables G-2, G-2a, G-3 and G-3a present a comparison of ARARs and RBTCLs derived for the commercial/industrial Site use scenarios for pentachlorophenol and PCDD/PCDF, respectively. Tables G-4, G-4a, G-5 and G-5a present a comparison of ARARs and RBTCLs derived for the hypothetical future residential Site use scenarios for pentachlorophenol and PCDD/PCDF, respectively. The existing average, RME, and maximum constituent concentrations are presented here for comparison with RBTCLs and ARARs. As discussed in Section G-1, Beazer East, Inc. feels the comparison of RBTCLs and ARARs with average values is appropriate for setting remedial goals because of the many conservative assumptions used to derive the RBTCLs. However, at the request of EPA, comparison of RBTCLs and ARARs with maximum values is the focus of this evaluation. In addition, the model used to derive soil target clean-up levels for the protection of ground water requires comparison of resulting target levels with maximum constituent concentrations in soil.
Section G.4.1 describes the comparison of the derived RBTCLs for soil with the appropriate standards. Section G.4.2 describes the comparison of RBTCLs derived in this document for surface water with the appropriate standards. Section G.4.3 describes the comparison of RBTCLs derived in this document for sediment with the appropriate values. Section G .4.4 describes the comparison of RBTCLs derived in this document for ground water with the appropriate standards. Section G.4.5 reviews the findings of the fish analysis presented in Section G.2.
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G.4.1-. Comparison of Soil RBTCLs and ARARs
Soil target clean-up levels for the protection of ground water were derived for pentachlorophenol
and 2,3,7,8-TCDD in a separate report (KER, 1992a). Section G.4.1.1 reviews the results of the
comparison of concentrations of constituents with soil target clean-up levels for the protection of
ground water and RBTCLs derived for soil in the commercial/industrial Site use scenario. Section
G.4.1.2 reviews the results of the comparison of constituent concentrations with soil target clean-
up levels for the protection of ground water and RBTCLs derived for soil in the residential Site use
scenario.
G.4.1.1 Commercial/Industrial Site Use Results
In surface and subsurface soils in Areas A, B, and D, the existing maximum concentrations of
constituents are lower than the RBTCLs (except the 1 E-06 RBTCL for Area B PCDD/PCDF
assuming no degradation occurs}, and the maximum concentrations of constituents are lower than
the ground water protection soil target levels. Thus, based on RBTCLs and protection of ground
water, no remediation of soils is likely to be required in any of these areas.
The Area C maximum concentrations of pentachlorophenol in surface and subsurface soil are
below the RBTCLs at the 1 E-5 risk level derived assuming that degradaUon occurs. The Area
C maximum concentration of pentachlorophenol in surface soil exceeds the RBTCLs at the 1 E-5
risk level for the on-site worker derived assuming degradation does not occur. The Area C
maximum concentration of pentachlorophenol in subsurface soil is below the RBTCLs at the 1 E-6
risk level derived assuming degradation does not occur, but exceeds the RBTCL for the on-site
worker at the 1 E-5 risk level assuming degradation does not occur. In addition, the maximum
concentrations of pentachlorophenol in Area C surface soil (3200 ppm) and subsurface soil (560
ppm) exceed the soil target level for the protection of ground water (95 ppm). Thus, remediation
may be required in Area C surface soil and subsurface soil.
The maximum concentrations of PCDD/PCDFs found in Area C surface soil exceed the human
health RBTCLs and the ground water protection soil target clean-up level, indicating that
remediation may be required for Area C surface soils. Concentrations of PCDD/PCDF in Area
C subsurface soil are below RBTCLs at the 1 E-5 risk level, and ground water protection values,
indicating no need for remediation of subsurface soils based on PCDD/PCDF.
G.4.1.2 Residential Site Use Results
The maximum concentrations of pentachlorophenol in Areas A, B and D soils are below the
RBTCLs for residential Site use. Areas A and D were not analyzed for PCDD/PCDF in surface
R:\P UBS\ PAOJE CTS\0845008\5 1 O.A PG G-23 July, 1992
or subsurface soil. The maximum concentrations of PCDD/PCDF in Area B surface soil exceed
the RBTCL at the 1 E-6 risk level derived assuming degradation, and the RBTCL at the 1 E-5 risk
level derived assuming no degradation occurs. The maximum constituent concentrations in Areas
A, B and D soils do not exceed the soil target clean-up levels for the protection of ground water
indicating that remediation of soils in these areas is likely not to be required based on risk.
The maximum concentration of pentachlorophenol in Area C surface soil exceeds the RBTCLs
at the 1 E-5 risk level derived assuming degradation occurs, and the RBTCL at the 1 E-4 risk level
derived assuming degradation does not occur. The maximum concentration of pentachlorophenol
in Area C subsurface soil exceeds only the RBTCL at the 1 E-6 risk level derived assuming no
degradation occurs.
The maximum concentration of pentachlorophenol in Area C surface soil (3200 ppm) and
subsurface soil (560 ppm), however, exceeds the soil target level for the protection of ground
water (95 ppm). This indicates that both surface and subsurface soil may be required for the
protection of ground water.
The maximum concentration of PCDD/PCDF in Area C surface soils exceeds the RBTCL, and
the maximum concentration in Area C surface soil exceeds the ground water protection soil target
clean-up level. Thus, remediation may be required for Area C surface soils. However, the lowest
RBTCL (5E-06 ppm) for PCDD/PCDFs in surface soil is greater than two orders of magnitude
smaller than the frequently used surface soil clean-up level of 0.001 ppm. Because of the
precedent of using this target clean-up level, ii is likely that it, or the value for the protection of
ground water, would be given preference here over the RBTCL (at the 1 E-06 risk level, assuming
degradation does not occur and assuming future residential Site use) for residential Site use.
G.4.2 Comparison of Surface Water RBTCLs and ARARs
The surface water bodies evaluated here include Fire Pond, Medlin Pond, and the Western Ditch.
The North Carolina surface water standard for 2,3,7,8-TCDD is 1.3E-11 ppm (or 0.013 ppq). The
isomer 2,3,7,8 TCDD was not detected in any surface water samples on the Site. Most of the
PCDD/PCDFs in surface water at the Site were "octa" congeners. The State standard is for
2,3, 7,8-TCDD in surface water. Because the State standard is driven almost exclusively by
consumption of 2,3,7,8-TCDD that has bioaccumulated in fish, this standard is not applicable to
congeners other than 2,3,7,8-TCDD unless an adjustment for bioaccumulation is also made. If
the State standard were adjusted to reflect the differences in bioaccumulation of the congeners
detected in surface water on the Site, it would likely increase by several orders of magnitude.
Because the State standard is not considered appropriate for comparison with concentrations of
PCDD/PCDF found at this Site, it is not addressed further in this evaluation. It is also important
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to note, however, that not only is the State standard considered inappropriate, but it is also not
achievable because it is well below the laboratory detection limit for 2,3, 7,8-TCDD.
Section G.4.2.1 reviews the results of the comparison of constituent concentrations with RBTCLs
derived for the commercial/industrial Site use scenario. Section G.4.2.2 reviews the results of the
comparison of constituent concentrations with RBTCLs derived for the residential. Site use
scenario.
The results of the ecological evaluation show that remediation of surface water in Fire Pond and
Medlin Pond may be required to protect aquatic organisms.
G.4.2.1 Commercial/Industrial Site Use Results
All constituent concentrations in surface water bodies evaluated here are less than the RBTCLs
at the 1 E-5 risk level derived for commercial/industrial Site use. Maximum measured
concentrations exceed RBTCLs at the 1 E-06 risk level for PCDD/PCDF in Fire Pond surface
water. Thus, no remediation of surface water is likely to be required based on potential human
exposure to surface water if the Site remains commercial/industrial in the future.
G.4.2.2 Residential Site Use Results
In the residential Site use evaluation, maximum concentrations of pentachlorophenol and
PCDD/PCDF in surface water, except PCDD/PCDF in Fire Pond, are lower than RBTCLs at the
1 E-6 risk level. This suggests that remediation of surface water is not likely to be required for the
Western Ditch.
The maximum PCDD/PCDF concentrations in Fire Pond exceed the RBTCLs at the 1 E-4 risk
level for residential Site use. In the unlikely event that the Site is developed for residential use
in the future, Fire Pond surface water may require remediation.
G.4.3 Comparison of Sediment RBTCLs
There are no ARARs for the constituents of interest in sediment. Comparison of maximum
measured sediment concentrations of pentachlorophenol with RBTCLs indicates no remediation
is required based on assumed risk. Comparison of maximum measured sediment concentrations
of dioxin with RBTCLs indicates remediation of sediment in the Fire Pond Discharge Stream may
be required if 1 E-06 is selected as the remedial risk goal for commercial/industrial Site use.
Remediation of Fire Pond sediment may also be required if 1 E-06 is selected as the remedial
goal for residential Site use. It is unlikely that the Site will be developed for residential use in the
R:\PUBS\PROJECTS\0845008\51 O.APG G-25 Jufy, 1992
future based· on current development in the area near the Site and the fact that an active
commercial/industrial facility currently operates on the Site.
G.4.4 Comparison of Ground Water RBTCLs and ARARs
Ground water was sampled off-Site and in three on-Site areas: the Former Lagoon Area, the
Eastern Area and the Western Area. The off-Site analysis was prepared for the
commercial/industrial Site use scenario which assumes that future off-site residents consume off-
site ground water as drinking water. The results of the comparison of RBTCLs and ARARs for
off-Site ground water assuming future commercial/industrial Site use is presented in Section
G.4.3.1. The on-Site analysis was prepared for the future residential Site use scenario because
this leads to the most health-protective result. Section G.4.4.2 presents the results of the
comparison of RBTCLs and ARARs for on-Site ground water assuming the Site is developed for.
residential use.
G.4.4.1 Commercial/Industrial Site Use Results
The maximum concentrations of pentachlorophenol in off-Site ground water are well below the
RBTCL and the MCL. Thus, no remediation of pentachlorophenol in off-Site ground water is
required on the basis of either potential human health effects or to meet appropriate ground water
ARARs for pentachlorophenol.
Both a North Carolina Ground Water Standard and a proposed MCL exist for 2,3,7,8-TCDD.
These standards can be compared with the Local Off-Site Resident RBTCL for ground water.
The maximum concentrations of PCDD/PCDFs in off-Site ground water are below the RBTCL,
the proposed MCL and the North Carolina Ground water Standard. Thus, no remediation of
PCDD/PCDFs in off-Site ground water is required on the basis of RBTCLs or ARARs.
The North Carolina MCL for 2-chlorophenol was compared with maximum off-Site ground water
concentrations of this constituent. Only one sample had a detected concentration of
2-chlorophenol and this was an "estimated" value (designated by the "J" qualifier in the laboratory
results). Because the only detected value for 2-chlorophenol in Off-Site Area groundwater is an
"estimated" value, and because the sampling location in which this value was estimated is located
within the bounds of the area that will be impacted by pumping of Site ground water, Off-Site Area
ground water is not identified as an area that may require remediation.
R:\P U BS\P ROJ E CTSl[)845008\S 1 0.A PG G-26 July. 1992
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G.4.4.2 Residential Site Use Results
On-Site ground water was evaluated for the hypothetical residential future use scenario. The
results of the comparison of Former Lagoon and Eastern Area constituent concentrations with
RBTCLs and ARARs are presented below. No constituent concentrations exceeded RBTCLs or
ARARs in the Western Area. Therefore, the Western Area is not discussed further in this
evaluation.
Former Lagoon Area Results
The maximum concentrations of pentachlorophenol in the Former Lagoon Area exceed the
RBTCLs and the MCL. These results suggest that remediation of pentachlorophenol may be
required in the Former Lagoon Area.
The maximum concentrations of PCDD/PCDF in the Former Lagoon Area exceed the RBTCLs,
State standard, and the proposed MCL, indicating that remediation of PCDD/PCDF may be
required in the Former Lagoon Area.
The maximum measured concentration of 2-chlorophenol in Former Lagoon Area ground water
is below the State MCL for this constituent, indicating that remediation is not required based on
this ARAR.
Eastern Area Results
The maximum concentration of pentachlorophenol in the Eastern Area exceeds the MCL and the
RBTCL. These results suggest that remediation of pentachlorophenol may be required in the
Eastern Area.
The maximum concentration of PCDD/PCDF in Eastern Area ground water is higher than the
RBTCL, the State standard and the proposed MCL. Thus, remediation of Eastern Area ground
water may be required at this Site.
The maximum measured concentration of 2-chlorophenol in Eastern Area ground water exceeds
the State MCL for this constituent. Thus, remediation of Eastern Area ground water may be
required.
A:\P U 85\PROJ E CTS\0845008\51 0 .A PG G-27 Ju~. 1992
G.4.5: Comparison of Fish RBTCLs and Existing Concentrations
There are no ARARs for the constituents of interest available for the evaluation of fish tissue.
Pentachlorophenol was not detected in fish tissue in either Fire Pond or Medlin Pond. The
maximum concentration of PCDD/PCDF in fish tissue in Fire Pond in the commercial/industrial
scenario exceeds the RBTCL at the 1 E-5 risk level for PCDD/PCDF in fish tissue. The maximum
concentration of PCDD/PCDF in fish tissue in Medlin Pond in the commercial/industrial scenario
exceeds the RBTCL at the 1 E-6 risk level. The maximum concentration of PCDD/PCDF exceeds
the RBTCL in Fire Pond at the 1 E-5 risk level in the future residential site use scenario. If the
Site is developed for residential use in the future, some action restricting consumption of fish from
Fire Pond may be required.
G.5 Summary and Conclusions
This Appendix has derived RBTCLs for the former Koppers Company, Inc. Site in Morrisville,
North Carolina. These RBTCLs are based upon potential assumed carcinogenic risks to human
receptors assuming two different future potential Site use conditions. The human health RBTCLs
were determined using the potential assumed carcinogenic risks estimated in the risk assessment
for this Site, which was conducted following EPA guidance and in accordance with standard risk
assessment methodology. Parallel analyses for ecological receptors suggest that remedial action
may be necessary for surface water in Fire Pond and Medlin Pond. However, because of the
uncertainty associated with the screening values used to estimate ecological risk, RBTCLs are
not calculated for ecological receptors.
As discussed in Section G.1, remediation decisions should be based on the comparison of
average constituent concentrations, not upper-bound concentrations, because of the inherent
conservatism built into the process. However, at the request of EPA, comparisons were made
with maximum constituent concentrations. It is important to note, however, that, in most cases,
use of the average constituent concentration instead of the maximum concentration does not
change the recommendations made here.
This Section is divided into four sub-sections. Section G.5.1 presents a summary of the RBTCLs
derived in this evaluation. Section G.5.2 summarizes the comparison of constituent
concentrations in various media with RBTCLs and ARARs available for those constituents.
Section G.5.3 presents a summary of the findings in this evaluation.
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G.5.1 · Summary of Human Health RBTCLs
The human health RBTCL.s derived in Section G.2 indicate that, based on potential assumed
risks, few environmental media and few areas of the Site may require remediation. The following
areas have maximum constituent concentrations that exceed RBTCL.s at the 1 E-04, 1 E-05 or 1 E-
06 risk levels in either or both potential future site use scenarios:
• surface soil Area B (dioxin at 1 E-06 for commercial/industrial use;
dioxin at 1 E-05 for residential use);
• surface soil Area C (pentachlorophenol at 1 E-05 for commercial/industrial use;
pentachlorophenol at 1 E-04 for residential use; dioxin at 1 E-04 for commercial/industrial
use and residential use);
• subsurface soil Area C (pentachlorophenol at 1 E-05 for commercial/industrial use and
1 E-06 for residential use; dioxin at 1 E-06 for commercial/industrial use and residential
use);
• surface water in Fire Pond (dioxin at 1 E-06 for commercial/industrial use; dioxin at 1 E-04
for residential use);
• sediment in Fire Pond Discharge Stream (dioxin at 1 E-06 for commercial/industrial use);
• sediment in Fire Pond (dioxin at 1 E-06 for residential use);
• on-Site ground water in the Eastern Area (pentachlorophenol at 1 E-05 and dioxin at 1 E-
04 for residential use);
• on-Site ground water in the Former Lagoon Area (pentachlorophenol at 1 E-04 and dioxin
at 1 E-04 for residential use);
• fish in Fire Pond (dioxin at 1 E-05 for commercial/industrial and residential use); and
• fish in Medlin Pond (dioxin at 1 E-06 for commercial/industrial use).
Because the Site is likely to remain commercial/industrial in the future, remediation at this Site
(based on risk) may be required in the following areas:
• surface soil in Area C;
• on-Site ground water in the Former Lagoon and the Eastern Area (based on MCL.s); and
• fish from Fire Pond.
These areas were those in which the potential assumed carcinogenic risk estimated in the risk
assessment was greater than 1 E-5 for one or more of the hypothetical potential receptors, or the
RBTCL.s derived were substantially lower than the existing constituent concentrations.
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In addition to the areas identified above based on the results of the human health evaluation,
surface water in Fire Pond and in Medlin Pond may require remediation based on the results of
the aquatic ecological evaluation.
G.5.2 Summary of Comparison of ARARs and RBTCLs
The following sections summarize the results of the comparison of RBTCLs, ARARs and
guidelines with existing maximum constituent concentrations in the various media investigated in
the baseline risk assessment. Table G-8 identifies the media and areas that may require
remediation, and summarizes the remedial goals recommended by Beazer East, Inc. for this Site.
G.5.2.1 Soil Summary
The results of the comparison of constituent concentrations with RBTCLs and relevant guidelines
indicates that only soil in Area C may require remediation. The potential need for remediation
in Area C surface and subsurface soils is supported by the results of the analysis of
pentachlorophenol in assumed future use scenarios; the maximum surface and subsurface soil
concentrations (3200 ppm and 560 ppm, respectively) exceed the soil level derived for the
protection of ground water (95 pm) and some of the relevant RBTCLs.
The potential need for remediation in Area C surface soils is also supported by the results of both
the commercial/industrial Site use and residential Site use analyses of PCDD/PCDF. In both
assumed future Site use scenarios, the maximum concentration of PCDD/PCDF in surface soil
(0.27 ppm) exceeds the RBTCLs derived for the receptors at various risk levels and the soil target
clean-up level for protection of ground water (0.007 ppm). Subsurface soil in Area C does not
require remediation based on PCDD/PCDF because, in all scenarios, maximum concentrations
of PCDD/PCDF are below RBTCLs and soil levels for the protection of ground water.
G.5.2.2 Surface Water Summary
As discussed in Section G.4.2, the State standard for 2,3,7,8-TCDD is not considered applicable
at this Site. lri this analysis, constituents in surface water in Fire Pond, Medlin Pond, and in the
Western Ditch were compared with RBTCLs. The results of these analyses show that the Fire
Pond may require remediation if the Site becomes residential in the future. If the Site remains
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commercial/industrial, as is more likely, no surface water remediation is required based on the
human health RBTCLs derived here.
The results of the aquatic ecological evaluation, however, identify surface water in Fire Pond and
Medlin Pond as areas that may require remediation.
G.5.2.3 Ground Water Summary
Ground water was evaluated off-Site and on-Site. Pentachlorophenol and PCDD/PCDF
concentrations in several ground water areas of interest exceeded RBTCLs and other ARARs.
Maximum concentrations of 2-chlorophenol in ground water in the Eastern and Off-Site Areas
exceed the North Carolina MCL for this constituent. The results of the off-Site ground water and
on-Site ground water analyses are presented below.
Off-Site Summary
The maximum concentrations of both pentachlorophenol and PCDD/PCDF are less than the most
conservative of either the RBTCL or ARAR for that constituent in ground water. Because no one
currently has access to off-Site ground water for drinking water, and no one is expected to in the
foreseeable future, and because no existing concentrations exceed RBTCLs or ARARs, no
remediation of off-Site ground water is required.
The maximum concentration of 2-chlorophenol in off-Site ground water exceeds the State MCL,
however, as described previously, Off-Site Area ground water is not specifically identified as an
area of potential remediation because the zone of influence of on-Site ground water remediation
will address the potential assumed risk attributable to 2-chlorophenol.
On-Site Summary
Two on-Site ground water areas may require remediation based on potential assumed risk only
if the Site becomes residential in the future: the Former Lagoon Area and Eastern Area. For this
hypothetical future use scenario, the maximum concentration of pentachlorophenol in the Former
Lagoon Area (1.49 ppm) exceeds both the MCL (0.001 ppm) and the RBTCLs. This indicates
that remediation of Former Lagoon Area ground water may be required.
The maximum concentration of PCDD/PCDF (SE-8 ppm) in the Former Lagoon Area exceeds the
RBTCLs, the proposed MCL (SE-8 ppm), and the State standard (2E-10 ppm) for dioxin. These
data indicate that remediation of Former Lagoon Area ground water may be required. Although
the State standard for dioxin is lower than the MCL, it may be appropriate to set the remediation
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goal for dioxin at the MCL because exposure to on-Site ground water as a drinking water source
is extremely unlikely, and the MCL is considered protective by the EPA. Even if the state
standard were selected, however, the practical quantitation limit for dioxin in water is 50 ppq (5E-8
ppm), which would be used as a default remedial goal in place of the state standard (2E-10 ppm).
In Eastern Area ground water, the maximum concentration of pentachlorophenol (0.05 ppm)
exceeds the RBTCL (0.004 ppm) and the MCL (0.001 ppm). The maximum concentration of
PCDD/PCDF in Eastern Area ground water (2E-7 ppm) also exceeds the RBTCLs, the proposed
MCL (5E-8 ppm) and the State standard (2E-10 ppm), indicating that remediation may be
required. As stated above, the MCL is the clean-up goal recommended by Beazer East, Inc. for
ground water at this Site.
The maximum concentration of 2-chlorophenol in Eastern Area ground water exceeds the State
MCL for this constituent indicating that remediation of Eastern Area ground water may be
required.
G.5.2.4 Fish Summary
The maximum concentration of PCDD/PCDF in fish from Fire Pond (4E-5 ppm) exceeds the
RBTCLs at the 1 E-05 and 1 E-06 risk levels (5E-6 ppm and 5E-7 ppm). This indicates that a
remedial measure restricting use of fish from Fire Pond may be needed.
G.5.3 Clean-Up Levels Evaluation Summary
Based on a comparison of existing maximum concentrations of pentachlorophenol and
PCDD/PCDF with human health RBTCLs, ARARs and other clean-up guidelines, and the results
of the ecological evaluation, the following media may require remediation at the Former Koppers
Company, Inc. Site in Morrisville, NC:
• surface and subsurface soil in Area C;
• surface water in Fire Pond;
• surface water in Medlin Pond;
• on-Site ground water in the Former Lagoon and Eastern Areas; and
• fish from Fire Pond.
Table G-8 presents a summary of the remedial goals presented in this evaluation.
The recommendations made in this appendix were derived from many conservative assumptions
and, thus, are health protective. Many of the RBTCLs derived here are based on the
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assumptions-that the Site is developed for residential use in the future. Because it is unlikely that
the Site will become residential, RBTCLs derived for residential use are not appropriate for this
Site.
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REFERENCES FOR APPENDIX G
Anderson, E., N. Browne, S. Duletsky, J. Tamig and T. Warn. 1985. Development of Statistical Distributions for Ranges of Standard Factors Used in Exposure Assessments. Office of Health and Environmental Assessment. EPA/600/8-85/010, Washington, D.C.
Eisler, R. 1986. Dioxin Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review. Biological Report 85 (1.8) U.S. Fish and Wildlife Service. Laurel, MD.
Keystone Environmental Resources, Inc. (KER) 1992a. "Development of Soil Clean-up Goals Protective of Groundwater Quality." Former Koppers Company, Inc. Superfund Site, Morrisville, NC. December 1991.
Keystone Environmental Resources, Inc. (KER) 1992b. Remedial Investigation Draft Report, Former Koppers Company, Inc. Superfund Site, Morrisville, North Carolina. June 1991.
Koporec, K. 1991. U.S. EPA Region IV. Personal Communication, April 23, 1991.
Oak Ridge National Laboratory (ORNL). 1986. User's Manual for Ecological Risk Assessment.
Rupp, E.M., F.L. Miller and C.F. Baes Ill. 1980. Some Results of Recent Surveys of Fish and Shellfish Consumption by Age and Region of U.S. Residents. Health Physics 39:165-175.
State of North Carolina (NC DNRCD). 1989. 1987 Ambient Air Quality. Department of Natural Resources and Community Development, Division of Environmental Management. May 1989.
U.S. EPA. 1980. Dietary Consumption Distribution of Selected Food Groups for the U.S. Population. Office of Pesticides and Toxic Substances. EPA 560/11-80/012.
U.S. EPA. 1986. Quality Criteria for Water. 1986. Office of Water Regulations and Standards. EPA 440/5-86/001.
U.S. EPA. 1988a. Recommendations for and Documentation of Biological Values for Use in Risk Assessment. Office of Research and Development, Cincinnati, OH. PB88-179874.
U.S. EPA. 1988b. Review of Ecological Risk Assessment Methods. EPA/230/10-88/041.
U.S. EPA. 1988c. Superfund Exposure Assessment Manual. Office of Emergency and Remedial Response, Washington, D.C. EPA/540/1-88/001.
U.S. EPA. 1989a. Ecological Assessment at Hazardous Waste Sites: A Field and Laboratory Reference. EPA/600-3-89/013.
U.S. EPA. 1989b. Exposure Factors Handbook. Office of Health and Environmental Assessment, Washington, D.C. EPA/600/8-89/043.
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U.S. EPA. -rn89c. Risk Assessment Guidance for Superfund. Volume I: Human Health
Evaluation Manual (Part A). Interim Final. Office of Emergency and Remedial Response,
Washington, D.C. EPA 540/1-89/002.
U.S. EPA. 1989d. Risk Assessment Guidance for Superfund. Volume II: Environmental
Evaluation Manual (Part B). Interim Final. Office of Emergency and Remedial Response,
Washington D.C. EPA 540/1-89/001.
U.S. EPA. 1990. Health Effects Assessment Summary Tables (HEAST). Third and Fourth
Quarters, F.Y. 1990. Office of Solid Waste and Emergency Response, Washington, D.C.
U.S. EPA. 1991 a. Integrated Risk Information System (IRIS). Environmental Criteria and
Assessment Office, Cincinnati, OH.
U.S. EPA. 1991b. Supplemental Region IV Risk Assessment Guidance. U.S. EPA, Region IV,
Atlanta, GA.
U.S. EPA. 1992. Region IV Waste Management Division Screening Values for Hazardous
Waste Sites. Version Dated 1/27/92.
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