United States Office of
Environmental Protection Emergency and
Agency Remedial Response
PB93-9637O2
EPA/RQD/R01-92/064
June 1992
£/EPA Superfund
Record of Decision:
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'"
NOTICE
The appendices listed in the index that are not found in this doCument have been removed at the request of
the issuing agency. They contain material which supplement. but adds no further applicable information to
the content of the document. All supplemental material is, however. contained in the administrative record
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50272.1 01
REPORT DOCUMENTATION 1" REPORT NO. I 2. 3. Reclplenrs Accession No.
PAGE EPA/ROD/ROl-92/064
4. Title and Subtitle 5. Report Date
SUPERFUND RECORD OF DECISION 06/30/92
Darling Hill Dump, VT 6.
First Remedial Action - Final
7. Aulhor(s) . 8. Performing Organlza1lon Rapt No.
9. Performing Orgalnlzallon Name and ~ 10. ProjectITaalclWorit Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Organization Name and Addr- 13. Type 01 Report &. Period Covered
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. Supplementary Notes
PB93-963702
16. Abstract (Umlt: 200 word8)
The 3.5-acre Darling Hill Dump site is an inactive solid waste disposal facility in
the town of Lyndon, Caledonia County, Vermont. Land use in the area is characterized
by open woodland, agricultural, and residential land. Steep slopes and the presence
of wetlands makes it Unlikely that the land in the immediate vicinity of the Dump will
be further developed for residential uses. In addition, the site lies within the
floodplain of the passumpsic River. Approximately 3,200 residents within the area are
served by the Lyndonville Municipal Well Field, located within O. 5 mil e to the
southwest. From 1952 to 1972, the site was operated by the Village of Lyndonville as
a disposal area accepting municipal and industrial waste. During this time, the
Darling Hill Dump was never formally re~lated or permitted. From 1972 to 1989,
Ray O. Parker and Sons operated the Darling Hill Dump and accepted primarily
construction debris and white goods. Approximately 100,000 cubic yards of material
are contained within the dump. As a result of detecting low levels of VOCs in the
ground water at the Lyndonville Municipal Wellfield, a number of investigations were
performed by EPA and the state, which revealed VOCs and metals in the ground water and
soil at the site. Subsequent investigations have revealed that the pumping of the
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - Darling Hill Dump, VT
First Remedial Action - Final
Contaminated Media: None
Key Contaminants: None
b. IdentlflerslOpen-Encled Terms
c. COSATI FieIdIGroup
18. Availability Statement 19. Security CIa.. (ThIs Report) 21. No. 01 Pages
None 32
20. Security Cia.. (This Page) 22. PrIce
Non~
01' IIONAL FORM 272 (4.77)
(See ANSl-Z39.18)
See InarmctJon. on R..,,-
(Formerly NTI5-3S)
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EPA/ROD/ROl-92/064
Darling Hill Dump, VT
First Remedial Action - Final
Abstract (Continued)
municipal wells inhibits flow of contaminants past the wellfield and that the site is
neither contaminating area surface waters nor posing a significant physical hazard to
area residences. This ROD addresses continued monitoring of ground water, surface water,
and sediments at the Darling Hill Dump Site. The results of the RI show that the levels
of organic compounds and metals do not appear to pose an unacceptable risk to human
,health or the environment. Therefore, there are no contaminants of concern affecting
this site.
The selected remedial action for this site includes no further action because significant
levels of contaminants are not present at the site. EPA, however, will continue to
monitor the ground water, surface water, and sediments for a 5-year period to ensure the
protectiveness of the no action remedy. The estimated net present worth of the 5-year
monitoring program is $292,000, which includes an annual monitoring cost of approximately
$77,000.
PERFORMANCE STANDARDS OR GOALS:
Not applicable.
~
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DECLARATION FOR THE
RECORD OF DECISION
SITE NAME AND LOCATION
Darling Hill Dump
Lyndon, Vermont
STATEMENT OF PURPOSE
This decision document presents the selected No Action decision
for the Darling Hill Dump site (the "Site"), located in Lyndon,
Vermont. This document was developed in accordance with the
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), and to the extent
practicable, the National contingency Plan (NCP); 40 CFRPart 300
et sea. (1990). The Regional Administrator for Region I of the'
United States Environmental Protection Agency (EPA) has been
delegated the authority to approve this Record of Decision.
"
The State of Vermont has not concurred with the No Action
decision.
STATEMENT OF BASIS
This decision is based on the administrative record compiled for
the Site which was developed in accordance with section 11~(k) of
CERCLA. The administrative record is available for public review
at the Cobleigh Public Library in Lyndonville; Vermont and at the
EPA Region I Waste Management Division Record Center in Boston,
Massachusetts. The administrative record index (attached as
Appendix D to the ~D) identifies each of the items which
comprise the administrative record upon which the selection of
the remedial action is based.
DESCRIPTION OF THE SELECTED REMEDY
EPA has determined that No Action is necessary to
contamination at the site. EPA will perform five
additional monitoring of the groundwater, surface
sediments.
address the
years of
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DECLARATION
EPA has determined that no further remedial action is necessary
at this site. Therefore, the site now qualifies for inclusion in
the "sites awaiting deletion" subcatagory of the Construction
Completion category of the National Priorities List.
As this is a decision for No Action, the statutory requirements
of CERCLA Section 121 for remedial actions are not applicable and
no five year review will be undertaken.
3'
Il)~
e Belaga
ional Administrator
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REG:IOH
:I
RECORD OP DBC:I8:I01f 81JJ111ARY
DARL:ING H:ILL DUKP
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Contents
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
DARLING HILL DUMP
TABLE OF CONTENTS
SITE NAME, LOCATION AND DESCRIPTION. .
. . . .
. . .
SITE HISTORY' ENFORCEMENT ACTIVITIES
. . .
. . . . .
A.
B.
Land Use' Response History. . . . . . . . . . .
Enforcement History. . . . . . . . . . . . . . .
COMMUNITY PARTICIPATION
. . .
. . .
. . . . . .
. . .
SCOPE' ROLE OF OPERABLE UNIT OR RESPONSE ACTION
SUMMARY OF SITE CHARACTERISTICS.
... . .
. . .
. . .
SUMMARY OF SITE RISKS. . . . . . . .
. . . .
. . . .
DESCRIPTION OF NO ACTION ............................
DOCUMENTATION OF NO SIGNIFICANT CHANGES
. . . . .
STATE ROLE
. . . .
. . . . . .
. . . .
. . . . . . .
APPENDIX A - Fiqures
APPENDIX B - Letter of Non-Concurrence
APPENDIX C - Responsiveness summary
APPENDIX D - Administrative Record Index
. .
Paqe Number
1
1
1
2
3
3
4
6
17
17
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DARLING HILL DUMP SITE
ROD DECISION SUMMARY
I.
SITE NAME, LOCATION AND DESCRIPTION
The Darling Hill Dump is a solid waste disposal facility located near the
village of Lyndonville, Vermont, within the Town of Lyndon, in Caledonia
.County, in the northeast part of Vermont (see Figure 1 attached). The Town
of Lyndon. has a population of 5,100 people, of which 1,400 live in the
village of Lyndonville. The Lyndonville Municipal Well Field, located
approximately 0.5 miles southwest of the Dump, provides water for
approximately 3,200 people.
The Darling Hill Dump is comprised of approximately 3.5 acres of land
sitting on the top of the north-facing slope of Darling Hill, which is a
narrow ridge between the East and West Branches of the Passumpsic River.
The narrow ridge is comprised of glacial deposits and can be characterized
as a kame terrace. There is an area containing wetlands and a floodplain
about 300 feet below the Dump along the west Branch of the Passumpsic
River. The Darling Hill Dump is bounded to the east and south by Darling
Hill Road. Darling Hill Road intersects state route 114 one-half mile
south of the Darling Hill Dump. The land east of Darling Hill Road slopes
steeply downward to the east branch of the Passumpsic River. West of the
Darling Hill Dump is a woodland area which slopes steeply down to the west
branch of the Passumpsic River.
A more complete description of the site can be found in the Remedial
Investigation Report on pages 4 and' 5~
II.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
A.
Land Use and Response History
The Darling Hill Dump. was open woodland prior to the development of the
Dump. steep slopes and the presence of wetlands make it unlikely that the
land in the immediate vicinity of the Dump could be used for residential
development. In addition, the small surface area of the Darling Hill Dump
and the marginal stability of the slopes of the. Darling Hill Dump would
make the site a poor location for future development. The area surrounding
the Darling Hill Dump is predominantly open agricultural and residential
land.
The Darling Hill Dump began operation in 1952 as a disposal area for .
mupicipal and industrial wastes. The Darling Hill Dump was never formally
regulated or permitted. The material disposed of at the Darling Hill Dump
included white goods, lumber, stumps, furniture, cardboard, drums, cans and
other containers, tires, automobiles, household refuse, construction
debris, and industrial wastes including solvents. The majority of the
material disposed after 1972 was construction debris and white goods.
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Darling Hill Dump.
The Darling Hill Dump was operated by the village of Lyndonville from 1952
until 1972. In 1972, operation of the facility was transferred to Ray o.
Parker and Sons, Inc. The facility was operated by Ray o. Parker and Sons,
Inc. until 1989 when the Darling Hill Dump ceased operation. The Darling
Hill Dump was originally owned by Alfred E. smith until it was purchased by
Egypt Land Farm, Inc. in 1983. .
In 1982, routine testing by the State of Vermont revealed the presence of
low levels of volatile organic compounds (VOC) in the groundwater of the
village of Lyndonville Municipal Wellfield. Further testing by the State
of Vermont was performed to confirm the contamination. In 1985, the State
of Vermont completed a preliminary assessment and site inspection of the
Darling Hill Dump as a potential source of the contamination. Based upon
these studies, EPA performed an Expanded site Inspection of the Darling
Hill Dump from 1986 to 1989 to more accurately identify the source of the
Municipal Wellfield contamination. Based upon these investigations, EPA
proposed the Darling Hill Dump for inclusion on the National Priorities
List (NPL) on June 24, 1988. The Darling Hill Dump was finalized on the
NPL on October 4, 1989.
A more detailed description of the Site history can be found in the
Remedial Investigation Report on pages 5 and 6.
B.
Enforcement History
On May 2, 1989 EPA notified approximately eight parties who either owned or
operated the facility, generated wastes that were shipped to the facility,
arranged for the disposal of wastes at the facility, or transported wastes
to the facility of their potential liability with respect to the site. On
June 23, 1989, negotiations commenced with these potentially responsible
parties (PRPs) regarding the settlement of the PRP's liability at the site.
EPA added a ninth party to the list of PRPs during July 1989.
The PRPs formed a steering committee and negotiations took place which have
resulted in the development of three Administrative Orders. The first was
an Administrative Order by Consent, EPA Docket No. I-89-1088, under which
four PRPs agreed to perform the remedial investigation and feasibility
study (RIfFS) under EPA oversight. The second order was an Administrative
Consent Order, EPA Docket 1-89-1090, under which "three PRPs agreed to
install a carbon treatment system at the Lyndonville Municipal Wellfield.
The third order was an Administrative Agreement by Consent, EPA Docket No.
1-89-1089, under which EPA recovered its past costs.
The PRPs have been active in the remedy selection process for this site.
The PRPs performed the RIfFS and Risk Assessment for the site. The PRPs
also presented technical comments on the Proposed Plan that were summarized
in the Responsiveness summary and were included in the Administrative
Record.
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III. COMMUNITY PARTICIPATION
Throughout the Site's history, community concern and involvement has been
moderate to low. EPA has kept the community and other interested parties
apprised of the site activities through informational meetings, fact
sheets, press releases and public meetings.
EPA conducted interviews with local officials and residents during January
of 1990 to assess community concerns. A public availability session to
provide information regarding upcoming activities and to receive additional
community input was held on January 31, 1990. During June 1990, EPA
-released a community relations plan which outlined a program to address
community concerns and keep citizens informed about and involved in
remedial activities. In september 1991, EPA issued a fact sheet updating
the community regarding the on-going investigations at the site. In
January 1992, EPA issued a fact sheet summarizing the results of the
Remedial Investigation (RI) and the Baseline Risk Assessment (BRA). On
February 4, 1992, EPA held an informational meeting regarding the RI and
BRA in Lyndonville, Vermont.
On April 9, 1992, EPA made the Administrative Record available for public
review at EPA's offices in Boston and at the Cobleigh Public Library in
Lyndonville, Vermont. EPA has also established a repository for site
information at the Municipal Offices of the village of Lyndonville. EPA
published a notice and brief analysis of the Proposed Plan in the Caledonia
Record on March 26, 1992 and made the plan available to the public at the
cobleigh Public Library and the Municipal Offices of Lyndonville, Vermont.
On April 9, 1992 EPA held an informational meeting to discuss the results
of the Remedial Investigation and to present the Agency's Proposed Plan.
Also during this meeting, the Agency answered questions from the public.
From April 10, 1992 to May 9, 1992, the Agency held a 30 day public comment
period to accept public comment on the alternatives presented in the
Feasibility Study and the Proposed Plan and on any other documents
previously released to the public. On May 5, 1992, the Agency held a
public meeting to discuss the Proposed Plan and to accept any oral
comments. A transcript of this meeting and the comments and the Agency's
response to comments are included in the attached responsiveness summary.
IV.
SCOPE AND ROLE OF OPERABLE UNIT OR RESPONSE ACTION
EPA has determined that no further CERCLA action is required at the Darling
Hill Dump Site. The levels of organic compounds and metals that were
detected in the soil and groundwater at the site do not appear to pose an
unacceptable risk to human health or the environment.
No five year review will be undertaken, but EPA will continue to monitor
the groundwater, surface water, and sediments for a period of five years.
The decision by EPA not to pursue further action at the site is not a
determination that no action is warranted under other regulations and
statutes. EPA has decided that the CERCLA cleanup authority is not the
appropriate mechanism to handle the closure of the Dump. However, the
State of Vermont has hazardous waste and solid waste regulations that apply
to the Darling Hill Dump. The State's authority under their laws is in no
-------
way limited by EPA's No Action decision.
EPA has the authority to revisit the No Action decision even if the. Site is
removed from the NPL. This could occur if future conditions indicate that
an unacceptable risk to human health or the environment would result from
the exposure to contaminants at the site.
v.
SUMMARY OP SITE CHARACTERISTICS
Chapter 1 of the Feasibility study contains an overview of the Remedial'
Investigation. The significant findings of the Remedial Investigation are
summarized below.
A. Soils: The surface soils on the Dump, the soils within the
debris mass of the Dump, the subsurface soils below the debris mass of
the Dump, and the subsurface soils adjacent to the debris mass of the
Dump were tested for the presence of contamination. See Figure 2 for
a profile of the soil contamination.
No organic contamination was detected in the soil samples taken from
the areas adjacent to or below the debris mass of the Dump. Metal
concentrations above background levels were detected in the soil
samples taken adjacent to and below the debris mass of the Dump. This
indicates that the metals concentrations in these samples exceeded the
level of metals detected in samples that were taken from a location
which is considered uncontaminated. The elevated levels of metals in
the subsurface soils adjacent to and below the debris mass would only
represent a problem if the metals were to migrate into the ground
. water at levels that would exceed drinking water standards. Since
metals are naturally occurring, it is common to find some level of
various metals in both the soils and ground water. See sections 4.2,
6.1, and 7.3 of the RI Report for more information.
A wide range of organic and metal contamination was detected in the
surface soils of the Dump and the soils within the debris mass of the
Dump. A wide range of polycyclic aromatic hydrocarbons (PARs) at
concentrations up to 3 parts per million (ppm) were detected in
surficial samples. Volatile organic compounds, PAHs, PCBs and a few
. pesticides were also detected at low concentrations. Metals.
concentrations significantly above background were detected in the
surface soils. These metals could present a problem if significant.
quantities were to migrate into the Passumpsic River.
Higher concentrations of VOCs and metals were detected in the
subsurface soils within the debris mass of the Dump. The
concentrations of PCBs and PAHs in the debris mass were lower than
those detected in the surface soils. Metals were also detected above
background concentrations in subsurface soils.
The surface soil data is used to evaluate the potential threat from
contact with the surface soils of the Dump. The contamination in the
subsurface soil within the debris mass is used to assess the amount of
source material that is still contributing contamination to the ground
water. For more information see Sections 2.4.4, 4.1.3, 4.2, 6.1, and
7.3 of the RI Report.
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B. Groundwater: Groundwater in the vicinity of the Darling Hill
Dump site flows primarily within a single overburden aquifer (ranging
from 40 to 100 feet in thickness). Some groundwater from the
overburden aquifer can also be found in the fractures of the bedrock
found below the overburden. The RI data indicate that it is unlikely
that a consistent pattern of fractures exists which would result in
the bedrock aquifer being a major source of contaminated groundwater.
Several VOCs including trichloroethene (TCE), 1,2-dichloroethene (1,2-
DCE), and tetrachloroethene (PCE) were detected above drinking water
standards in the groundwater at the site. Low levels of TCE and 1,2-
DCE (1 part per billion (ppb) each) were found in the bedrock
groundwater monitoring well located approximately 750 feet southwest
of the Dump. Much higher concentrations of TCE, 1,2-DCE, and PCE (up
to 160, 240, and 10 ppb, respectively) were found in the shallow
groundwater adjacent to the southern boundary of the Darling Hill
Dump. The EPA drinking water standards for these compounds are 5 ppb
for TCE, 70 ppb for 1,2-DCE, and 5 ppb for PCE. Vermont has the same
standards for TCE and 1,2-DCE, but the Vermont standard for PCE is 0.7
ppb. Only TCE (up to 15 ppb) was detected in the groundwater between
the Dump and the Municipal Well Field at concentrations exceeding EPA
and Vermont drinking water standards.
Two metals (chromium and lead) were also detected at concentrations
above drinking water standards in the groundwater samples taken in the
immediate vicinity of the Darling Hill Dump. No metals above drinking
water standards were detected in the monitoring wells away from the
Darling Hill Dump.
See Figures 3 and 4, which are attached, for a map of the contaminant
plume (and the locations where drinking water standards were exceeded)
and Sections 2.3, 4.3, 6.2, and 7.1 of the RI Report for more
information regarding groundwater contamination.
c. Groundwater Flow: RI data indicate that groundwater flows from
the Darling Hill Dump towards the Lyndonville Municipal Well Field.
This can be seen by looking at the distribution of contamination as
shown in Figures 3 and 4, which are attached. The contamination
originates as leachate which forms from the contact of infiltrating
wat~r with waste within the Darling Hill Dump. The leachate then
percolates through the unsaturated soils down to the ground water
aquifer. The contamination first contacts the shallow portion of the
aquifer beneath and immediately adjacent to the Darling Hill Dump.
The contamination then follows the natural flow of the groundwater and
sinks to the lower one third of the aquifer within a very short
distance from "the Darling Hill Dump. The natural flow of the
groundwater causes the contamination to flow along the base of the
aquifer, forming a plume which extends to the Lyndonville Municipal
Well Field. The pumping of the municipal wells, which pulls ground
water toward the wells from all directions, inhibits the flow of
contaminants past the well field. The Lyndonville Municipal Well
Field therefore serves as a containment system for the contamination.
See Figure 4 for a cross-sectional view of the groundwater
contamination and groundwater flow directions and Sections 2.3.5, 3.3,
and 5.3 of the"RI for more information regarding groundwater flow.
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D. Surface Wa~er and Sedimen~: The surface water and sediments of
the east and west branches of the Passumpsic River were tested to
evaluate whether contaminants from the site are entering the river.
The tests showed that the site is not contaminating the surface water
in either branch of the river. The sediments of the river also do not
contain any site-related contamination. At this time, the Darling
Hill Dump site is not adversely affecting either branch of the
Passumpsic River. Further information regarding the surface water and
sediment studies can be found in sections 2.5, 3.4, 4.4, 6.4, and 7.2
of the RI Report. .
E. Air: To evaluate the potential threat from air emissions from
the Dump, several studies were performed. First, the air was tested
using field screening instruments to detect the presence of any gross
contamination. Then, the air was sampled using more sophisticated air
sampling devices to confirm that only low levels of contamination were
present. In addition, the surface soils and subsurface soils of the
Dump were tested to determine if they could represent a source of
unacceptable air emissions. The results of these studies at the Site
reveal that the air emissions from the Dump are not a threat to human
health or the environment. Further information regarding the air
studies can be found in sections 2.4, 4.1, 6.3, and 7.3 of the RI
Report.
F. s~abilitv of the Dump: To evaluate the stability of the Dump
several studies were performed. Monuments were installed on the Dump
surface to m~asure surface movements of the Dump. Inclinometers were
installed within the Dump and adjacent to the Dump to measure the
potential for large scale slope failure. The results indicate that
the Dump is only marginally stable. The data did not allow for a
prediction of when the slopes may fail. The Dump was fenced during
the RI/FS to restrict exposure to the debris mass. The Dump does
represent a significant physical hazard to anyone in the area
immediately below the Dump. See sections 3.2.3 and 7.4 of the RI and
section 2 of the _FS for more information on slope stability.
~~-, '
A complete discussion of site characteristics can be found in the Remedial
Investigation Report on Pages 57-181.
VI.
SUMMARY OF SITE RISKS
A Risk Assessment (RA) was performed to estimate the probability and
magnitude of potential adverse human health and environmental effects from
exposure to contaminants associated with the site. The public health risk
assessment followed a four step process: 1) contaminant identification,
which identified those hazardous substances which, given the specifics of
the site were of significant concern: 2) exposure assessment, which
identified actual or potential exposure pathways, characterized the
potentially exposed populations, and determined the extent of possible
exposure: 3) toxicity assessment, which considered the types and magnitude
of adverse health effects associated with exposure to hazardous substances,
and 4) risk characterization, which integrated the three earlier steps to
summarize the potential and actual risks posed by hazardous substances at
the Site, including carcinogenic and non-carcinogenic risks. The results
of the public health risk assessment for the Darling Hill Dump Site are
discussed below, followed by the conclusions of the environmental risk
assessment.
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Twenty-nine contaminants of concern, listed in Tables 1 and 2 of this
Record of Decision were selected for evaluation in the Risk Assessment.
These contaminants constitute a representative subset of the more than
fifty contaminants identified at the site during the Remedial
Investigation. Due to the low levels of contamination detected at the site
and the relatively low number of contaminants detected, almost all were
included as contaminants of concern. The twenty-nine contaminants of
concern were selected to represent potential site related hazards based on
toxicity, concentration, frequency of detection, and mobility and
persistence in the environment. A summary of the health effects of each of
the contaminants of concern can be found in section 3.1.1, pages 43-44, and
Appendix B of the Risk Assessment.
TABLE 1: SUMMARY OF CONTAMINANTS
OF CONCERN IN (GROUND WATER)
J
Average
Concentration
(uq/l)
Maximum
Concentration
(uq/l)
Frequency
of Detection
contaminants
of Concern
Benzene
Carbon Disulfide
chromium
1,2-Dichloroethene
Diethylpthalate
Tetrachloroethene
Toluene
Trichloroethene
1.9
1.8
8.5
3.7
5.5
2.0
2.5
2.5
2.0
150
95
240
49
10
36
160
5/91
6/82
5/24
27/82
1/24
8/91
33/91
26/91
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TABLE 2: SUMMARY OF CONTAMINANTS
OF CONCERN IN (SOILS)
contaminants
of Concern
Average
Concentration
(ua/l)
Anthracene 419
Arsenic 4,300
Benzo (a) anthracene 495
Benzo (a) pyrene 484
Benzo (b) flouranthene 505
Benzo (g,h,i) perylene 471
Benzo (k) flouranthene 440
bis(2-ethylhexyl)pthalate 889
cadmium 2,000
chromium 23,800
chrysene 495
DDD 22
DDE 22
DDT 31
Di-n-butylpthalate 559
Flouranthene 517
Indeno (1,2,3-cd) pyrene 463
Mercury 100
Nickel 14,200
PCB 280
Phenanthrene 515
pyrene 491
Maximum
Concentration
(uq/l)
290
49,700
1,100
920
1,300
740
430
19,000
10,600
69,500
1,100
31
28
130
2,200
3,000
640
240
40,800
1,900
1,500
1,900
Frequency
of Detection
1/8
7/8
1/8
1/8
1/8
1/8
1/8
2/8
) 6/8
8/8
1/8
1/8
1/8
2/8
1/8
2/8
1/8
1/8
6/8
3/8
1/8
2/8
'~-~-~ '
Potential human health effects associated with exposure to the contaminants
of concern were estimated quantitatively or qualitatively through the
development of several hypothetical exposure pathways. These pathw~ys were
developed to reflect the potential for exposure to hazardous substances
based on the present uses, potential future uses, and location of the site.
The Darling Hill Dump is not considered a location that is suitable for
residential development, therefore only a trespasser scenario was developed
for direct contact and incidental ingestion of soil. This is due to the
small surface area of the Dump and the fact that the material deposited
within the Dump results in a surface that is not stable. The area
surrounding the Dump is currently agricultural and rural residential. The
following is a brief summary of the exposure pathways evaluated. A more
thorough description can be found in section 4.3 of the Risk Assessment.
For contaminated groundwater, exposure to a child (1-6 years) and an adult
were estimated. As part of the child exposure scenario, consumption of 1 .
li~er of groundwater per day was presumed. As part of the adult scenario,
thirty years of consuming 2 liters of groundwater per day was presumed.
A present use scenario, using these exposure assumptions, was developed
based upon the data collected from residential wells. A future use
scenario, using the above assumptions, was developed using the data
collected from residential wells and on-Site monitoring wells. For
contaminated soil, exposure to an adolescent (6-12 years) was estimated.
For the present use scenario, dermal contact and incidental ingestion of
-------
soils was evaluated assumimg 26 days of trespass per year for 6 years. For
the future use scenario, dermal contact and incidental ingestion of soils
was assuming 72 days of tresspass per year for 6 years. For each pathway
evaluated, an average and a reasonable maximum exposure (RME) estimate was
generated corresponding to exposure to the average and the maximum
concentration detected in that particular medium.
Excess lifetime cancer risks were determined for each exposure pathway by
multiplying the exposure level with the chemical specific cancer potency
factor. Cancer potency factors have been developed by EPA from
epidemiological or animal studies to reflect a conservative "upper bound"
of the risk posed by potentially carcinogenic compounds. That is, the true
risk is very unlikely to be greater than the risk predicted. The resulting
.risk estimates are expressed in scientific notation as a probability (e.g.
1 x 10.6 for 1/1,000,000) and indicate (using this example), that an .
individual is not likely to have greater than a one in a million chance of
developing cancer over 70 years as a result of site-related exposure as
defined to the compound at the stated concentration. CUrrent EPA practice
considers carcinogenic risks to be additive when assessing exposure to a
mixture of hazardous substances.
The hazard index was also calculated for each pathway as EPA's measure of
the potential for non-carcinogenic health effects. The hazard quotient is
calculated by dividing the exposure level by the reference dose (RfD) or
other suitable benchmark for non-carcinogenic health effects for an
individual compound. Reference doses have been developed by EPA to protect
sensitive individuals over the course of a lifetime and they reflect a
daily exposure level that is likely to be without an appreciable risk of an
adverse health effect. RfDsare derived from epidemiological or animal
studies and incorporate uncertainty factors to help ensure that adverse
health effects will not occur. The hazard quotient is often expressed as a
single value (e.g. 0.3) indicating the ratio of the stated exposure as
defined to the reference dose value (in this example, the exposure as
characterized is approximately one third of an acceptable exposure level
for the given compound). The hazard quotient is only considered additive
for compounds that have the same or similar toxic endpoints and the sum is
referred to as the Hazard Index (HI) (for example: the hazard quotient for
a compound known to produce liver damage should not be added to a second
whose toxic endpoint is kidney damage).
Table 3 depicts the carcinogenic
concern in groundwater evaluated
groundwater corresponding to the
exposure scenarios.
risk summary for the contaminants of
to reflect present ingestion of
average and the reasonable maximum
TABLE 3
CARCINOGENIC RISKS FOR THE PRESENT INGESTION
OF GROUNDWATER
contamin- Concen-
ant of tration
concern(C1ass) (uq/1)
avo max
Tetra- 0.4 1.9
Chloroethene(B2)
Exposure
Factor
(1/kq/day)
1.2X10-z
Cancer of
potency
(mq/kq/day)
5.1X10-z
Risk Estimate
avq RME
3xlO-f 1X10-6
-------
Table 4 depicts the non-carcinogenic risk summary for
concern in groundwater ~valuated to reflect potential
groundwater by an adult. The table includes both the
reasonable maximum exposure scenarios.
the contaminants of
present ingestion of
average and the
contamin-
ant of .
concern
Tetra-
Chloroethene
Toluene
Diethyl-
pthalate
TABLE 4
NON-CARCINOGENIC RISKS FOR THE PRESENT INGESTION
OF GROUNDWATER (Adult)
Target
Endpoint
of
Toxicity
2. 7x10-z (mq/k~daV)
1x10- liver
Concen-
tration
(ug/l)
avq max
0.4 1.9
Exposure
Factor
(l/kg/ day)
Reference
Dose
Hazard
Index
avq RME
1X10-5 5x10-3
0.4 4 2. 7X10-2 2x10 -, liver, kidney 6X10-5 6X10-4
7.9 49 2. 7X10-2 8X10-' growth rate 3X10-4 2x10-3
sum HI liver effects 1X10-3 6x10-2
HI growth effects 3x10 -4 2X10-3
Table 5 depicts the non-carcinogenic risk summary for the contaminants of
concern in groundwater evaluated to reflect present ingestion of
groundwater by a child. The table includes both the average and the
reasonable maximum exposure scenarios.
contamin-
ant of
concern
Tetra-
Chloroethene
Toluene
Diethyl-
pthalate
TABLE 5
NON-CARCINOGENIC RISKS FOR THE PRESENT INGESTION
OF GROUNDWATER (Child) .
Target
Endpoint
of
Toxicity
9. 6X10-z (mq/k~daV)
1x10- liver
Concen-
tration
(ug/l)
avq max
0.4 1.9
Exposure
Factor
(l/kg/day)
Reference
Dose
Hazard
Index
avq RME
4x10 -:s 2X10-2
0.4 4 9. 6X10-2 2x10 -, liver, kidney 2x10.4 2X10-3
7.9 49 9. 6X10-2 8x10 -, growth rate 1x10-3 6x10-3
Sum HI liver effects 4X10-3 2X10-2
HI growth effects 1x10 -4 6X10-3
10
-------
~
Table 6 depicts the carcinogenic
concern in groundwater evaluated
groundwater corresponding to the
exposure scenarios.
risk summary for the contaminants of
to reflect potential future ingestion of
average and the reasonable maximum
TABLE 6
CARCINOGENIC RISKS FOR THE POSSIBLE FUTURE INGESTION
OF GROUNDWATER
contamin- Concen- Exposure Cancer of
ant of tration Factor potency
Concern (Class) (ug/l) (l/kg/day) (mg/kg/day) Risk Estimate
aver max aver RME
Benzene (1\) 1.9 2 1.2Xl0-z 2. 9Xl0-z 7xlO-f 7Xl0-7
Tetra- 2 10 1.2Xl0-2 5.1Xl0-2 lxl 0 -6 6xlO-6
Chloroethene(B2) 1.2Xl0-2 1.1Xl0-2 3Xl0-7 2Xl0-5
Trichloro- 2.5 160
ethene (B2)
SUM 2xlO-6 3xlO-5
Table 7 depicts the non-carcinogenic risk summary for the contaminants of
concern in groundwater evaluated to reflect potential future ingestion of
groundwater corresponding to the average and the reasonable maximum
exposure scenarios.
TABLE 7
NON-CARCINOGENIC RISKS FOR THE POSSIBLE FUTURE INGESTION
OF GROUNDWATER (Adult)
Target
contamin- Concen- Exposure Reference Endpoint
ant of tration Factor Dose of Hazard
concern (ug/l) (l/kg/day) Toxicity Index
aver max (mq/~¥/daV) aver RME
ChromiumVI 8.5 95 2. 7Xl0-z 5xl0 none 5xl0 -z 5Xl0-1
chromiumIII 8.5 95 2. 7Xl0-2 1 liver 2xl0-4 3Xl0-3
Carbon 2.9 150 2. 7Xl0-2 lXl0-1 Feto- 8xl0 -4 4Xl0-2
Disulfide Toxicity
c,1,,2-Di- 3.7 240 2. 7Xl0-2 lXl0-2 Hemoglobin, lXl0-2 7xl0-1
Chloroethene liver
t,1,2-Di- 3.7 240 2. 7Xl0-2 lXl0-2 liver 5Xl0.3 3Xl0.1
Chloroethene.
Tetra- 2.0 10 2. 7Xl0-2 lXl0-2 liver 6xl0 -3 3xl0-2
Chloroethene
Toluene 2.5 36 2. 7Xl0-2 .2Xl0.' liver, kidney 3Xl0-4 5xl0-3
Diethyl- 5.5 49 2. 7Xl0-2 8Xl0-' growth rate 2Xl0-4 2Xl0-3
pt~alate
SUM* liver lXl0-z 7Xl0.'
11
-------
Table 8 depicts the non-carcinogenic risk summary for the contaminants of
concern in groundwater evaluated to reflect potential future ingestion of.
groundwater corresponding to the average and the reasonable maximum
exposure scenarios for a child.
TABLE 8
NON-CARCINOGENIC RISKS FOR THE POSSIBLE FUTURE INGESTION
OF GROUNDWATER (Child)
Target
contamin- Concen- Exposure Reference Endpoint
ant ot tration Factor Dose of Hazard
concern (ug/l) (l/kg/day) Toxicity Index
ava max (ma/k~/daV) ava RME
chromium VI 8.5. 95 9. 6x10-z 5x10. none 2X10.1 1.8
Chromium III 8.5 95 9. 6X10.2 1 liver 8X10.4 9X10-3
Carbon 2.9 150 9. 6X10.2 1x10 -, Feto- 3X10-3 1X10.1
Disulfide Toxicity
c,1,2-Di- 3.7 240 9. 6X10-2 1X10.2 Hemoglobin 4X10-2 2.3
Chloroethene
t,1,2-Di- 3.7 240 9. 6X10-2 1x10 -2 liver 2x10 -2 1.2
Chloroethene
Tetra- 2.0 10 9. 6X10-2 1X10-2 liver 2X10-2 1X10.1
Chloroethene
Toluene 2.5 36 9.6X10-2 2X10-' liver, kidney 8X10-4 1X10-2
Diethyl- 5.5 49 9. 6X10-2 8x10 -, growth rate 7X10-4 6X10-3
pthalate
*Sum If t-l,2-Dichloroethene and Chromium +3
are present then the liver HI would equal 4x10-2 1.3
'~-...-...-<'
If c-l,2-Dichloroethene is present then
the hematocrit hemoglobin HI would equal 4X10-2 2.3
If Chromium +6 is present then the HI would be 2X10-' 1.8
* note: speciation of chromium and 1,2-dichloroethene was not performed
during the RI/FS analytical evaluations, therefore the risk assessment
evaluated the possibility any combination of chromium and 1,2-
dichloroethene.
-------
"
Table 9 depicts the carcinogenic risk summary for the contaminants of
concern in soil evaluated to reflect potential present incidental ingestion
and dermal .~ontact of soil corresponding to the average and the reasonable
maximum exposure scenarios for a trespasser.
TABLE 9
CARCiNOGENiC RiSKS FOR THE POSSiBLE PRESENT iNCiDENTAL iNGESTiON
AND DERMAL CONTACT WITH SOIL(TRESPASSER)
contamin- Concen- Exposure Cancer of
ant of tration Factor potency
Concern(Class) (mq/kq) (mq/kq/day) (mq/kq/day) Risk Estimate
ava max ava RME
.Arsenic (A) 4.3 49.7 2.1X10-a 1.75 2xlO-7 2X10-6
Benzo (a)- .5 1.1 2. 5X10-8 11.5 lxlO-7 3xlO-7
anthracene (B2) 2. 5X10-a lX10-7 3X10-7
Benzo (a)- .48 .92 11.5
pyrene(B2) 2. 5Xl0-a 2x10 -7 4Xl0-7
Benzo (b)- .52 1.3 11.5
flouranthene(B2) 2. 5X10-8 lx10 -7 1X10-7
Benzo (k)- .44 .43 11.5
flouranthene(B2) 2. 5X10-8 lx10 -7 3X10-7
chrysene(B2) .50 1.1 11.5
Indeno(1,2,3)- .46 .. .64 2. 5X10-8 11.5 1X10-7 2X10-7
pyrene(B2) 1.1X10-8 4x10 -8 2x10-7
PCB(B2) .47 1.99 7.7
bis(2-ethyl- .89 19.0 2. 5X10-8 1.4X10-2 3X10-10 7 X 1 0-9
hexyl)pthalate(B2) 1.2Xl0-8 2. 4Xl0-1 6xl0 -n aXl0-11
DDD (B2) .02 .03
DDE (B2) .02 .03 1.0X10-8 3. 4X10-1 aX10-11 1xlO.10
DDT (B2) .03 .13 1.1X10.8 3. 4Xl0.1 1xl0 -10 5xl0 -10
SUM lxlO -6 3. 6xlO-S
13
. - .-.-..--- ._P'
-------
Table 10 depicts the non-carcinogenic risk summary for the contaminants of
concern in soil evaluated to reflect potential present incidental ingestion
and dermal contact of soil corresponding to the average and the reasonable
maximum exposure scenarios for a trespasser.
TABLE 10
NON-CARCINOGENIC RISKS FOR THE POSSIBLE PRESENT INCIDENTAL
AND DERMAL CONTACT WITH SOIL (TRESPASSER)
Target
Exposure Reference Endpoint
Factor Dose of
(mg/kg/day) Toxicity
(ma/ka/dav)
1.4X10-5 keratosis
5X10.4 kidney
5X10.3 no effect
3X10~ CNS effects
2x10-2 reduced weight
4Xl0~ no effect
4x10-3
contamin-
ant of
concern
3.0
1.5
1.9
19.0
2.2
.03
INGESTION
Hazard
Index
RME
8X10-3
5X10-3
3X10-3
2X10-4
5X10-4
3X10-7
6X10-5
7.1X10.1
7.1X10.7
7.1X10.7
7.1X10.7
7.1X10.7
8.9x10-7
8.9xl0.7
ava
7X10-4
1x10 -4
1X10-3
8X10-5
2X10.4
4x10 -7
4X10-5
Concen-
tration
(mg/kg)
ava max
Arsenic 4.3 49.7
cadmium 2.0 10.6
Chromium 23.8 69.5
Mercury .1 .24
Nickel 14.2 40.8
Anthracene .42 .29
Benzo(g,h,i)-.47 .74
perylene
Flouranthene .52
Phenanthrene .52
pyrene .49
bis(2-ethyl- .89
hexyl)pthalate
Di-n-butyl .56
pthalate
DDT
8.9X10-7 4X10-2 nephropathy 4X10-6 2Xl0-5
8.9Xl0.7 4Xl0-3 4Xl0-5. 1Xl0-4
8.9X10.7 3X10-2 nephropathy 5X10-6 2 X 1 0 -5
8.9X10.7 2x10-2 increased 1X10-5 3 X 10-4
8.9X10-7 1x10.' liver weight 2X10-6 6X10-6
increased
3.9X10.7 5X10-4 mortality 8X10-6 3X10-5
---
SUM. 3X10-3 2X10-2
.13
-------
b
Table 11 depicts the carcinogenic risk summary for the contaminants of
concern in soil evaluated to reflect potential future incidental ingestion
and dermal contact of soil corresponding to the average and the reasonable
maximum exposure scenarios for a trespasser.
TABLE 11
CARCINOGENIC RISRS FOR THE POSSIBLE FUTURE INCIDENTAL INGESTION
AND DERMAL CONTACT WITH SOIL(TRESPASSER)
contamin- Concen- Exposure Cancer of
ant of tration Factor potency
Concern (Class) (mq/kq) (mq/kq/day) (mq/kq/day) Risk Estimate
aver max aver RME
Arsenic (A) 4.3 49.7 6.1x10-8 1.75 5xlO-' 5X10-6
Benzo (a)- .5 1.1 7. 6x10-8 11.5 4xlO-7 1xl 0-6
anthracene (B2) 7. 6X10-8 4X10-7
Benzo (a)- .48 .92 11.5 8X10-7
pyrene(B2) 7. 6x10-8 4x10 -7 1X10-6
Benzo (b)- .52 1.3 11.5
flouranthene(B2) 7. 6X10-8
Benzo (k)- .44 .43 11.5 4X10-7 4X10-7
flouranthene(B2) 7. 6X10-8
chrysene(B2) .50 1.1 11.5 4X10-7 1x 1 0-6
Indeno(1,2,3)- .46 .64 7.6X10-8 11.5 4x10 -7 6X10-7
pyrene(B2) 3. 3x10-8 1X10-7
PCB(B2) .47 1.99 7.7 5X10-7
bis(2-ethyl- .89 19.0 7. 6Xl0-8 1. 4Xl0-Z lxl0 -9 2X10-8
hexyl)ptha1ate(B2) 3. 6X10-8 2. 4X10-1 2X10-10 3X10-10
DDD(B2l .02 .03
DDE(B2) .02 .03 3.1X10-8 3. 4X10-1 2X10-10 3X10-10
DDT(B2) .03 .13 3. 3X10-8 3. 4X10-1 4X10-10 2X10-9
SUM 3xlO-6 1xl 0-5
-------
Table 12 depicts the nori-c~rcinogenic risk summary for the contaminants of
concern in soil evaluated to reflect potential future incidental ingestion
and dermal contact of soil corresponding to the average and the reasonable
maximum exposure scenarios for a trespasser.
TABLE 12
NON-CARCINOGENIC RISKS FOR THE POSSIBLE INCIDENTAL INGESTION
AND DERMAL CONTACT WITH SOIL (TRESPASSER)
Target
Exposure Reference Endpoint
Factor Dose of
(mg/kg/day) Toxicity
(ma/ka/dav)
1.4X10-3 keratosis
5X10-4 kidney
5X10-3 no effect
3X10-4 CNS effects
2X10-2 reduced weight
4X10~ no effect
4X10-3
contamin-
ant of
concern
Concen-
tration
(mg/kg)
ava max
Arsenic 4.3 49.7
cadmium 2.0 10.6
Chromium 23.8 69.5
Mercury .1 .24
Nickel 14.2 40.8
Anthracene .42 .29
Benzo(g,h,i)-.47 .74
perylene
Flouranthene .52
Phenanthrene .52
pyrene .49
bis(2ethyl .89
hexyl)pthalate
Di-n-butyl .56
pthalate
DDT
3.0
1.5
1.9
19.0
2.2
.03
7.1x10-1
7.1X10-7
7.1X10-7
7.1Xl0-7
7.1Xl0-7
8.9X10-7
8.9X10-7
8.9X10-7
8.9X10-7
8.9X10-7
8.9X10-7
8.9X10-7
.13
3.9X10-7
4x10-2
4X10-3
3X10-2
2X10-2
nephropathy
nephropathy
increased
liver weight
increased
mortality
Hazard
Index
RME
3X10-2
2x10 -2
1X10-2
6X10-4
2X10-3
7xlO -5
2X10-4
7X10-5
4xlO -4
5xlO -5
8X10-4
ava
2Xl0-.s
3xl0 -3
3xl0 -3
2xl0 -4
5Xl0-4
9X10-5
lx10 -4
lX10-5
lX10-4
2X10-5
4X10-5
5X10-6
2X10-5
lX10-4
2X10~5
lx 1 0 -4
5X10-2
The maximum future cancer risk- from exposure to groundwater is estimated as
3x10-5 and the maximum future hazard index is 2.3 for a child. The maximum
future cancer risk from exposure to contaminated site soils was estimated
as 1X10-s and the maximum hazard index is 5xlO-2. The maximum carcinogenic
risks resulting from exposure to Site related contamination are well with
the range of carcinogenic risk considered acceptable by EPA. The hazard
index is below the concern level of one for soil and slightly exceeds one
for the child exposure to groundwater.
SUM*
lX10.'
5X10-4
E~A has a CERCLA mandate to manage risk resulting from actual or potential
exposure to hazardous substances. Exposures resulting in a cancer risk
wi thin the range of 10-4 to 10'6 are considered acceptable cancer risks by
EPA. Non-carcinogenic risks with a hazard index below--one are also
considered acceptable. The slight exceedence of the hazard index for the
child exposure does not indicate a need for action at the Site. EPA's
decision as to whether action is warranted when the cancer risk range is
not exceeded is based upon site specific conditions.
The site specific conditions at the Darling Hill Dump site support the
decision to not take action. There are very low levels of contaminants in
the majority of the groundwater throughout the Site. One sample point in
an area, that is not very accessible, is responsible for the majority of
-------
the groundwater risk. The estimated cancer risk from exposure to
contamination outside that one point is 3x10-6. Figures 5 and 6 show the
distribution of carcinogenic risk for ingestion of groundwater. Figure 7
is a profile of the location where the maximum concentrations were
detected. As shown in figures 5-7, the cancer risks estimated from
exposure to the most contaminated groundwater can be considered very
conservative. The fact that the cancer risk that would result from
exposure to the most contaminated groundwater would be well within the
acceptable risk range strongly supports the decision to select No Action.
An environmental assessment was performed at the site. At this time the
Site is not impacting the West branch of the Passumpsic River or the
adjacent wetlands or floodplain. If there was a major failure of the
debris mass, then there is the potential for increased levels of
'contamination to reach the West branch of the Passumpsic.
VII.
Description of No Action Alternative
There are no construction activities associated with the No Action
decision. However, monitoring will be performed to provide more
information regarding the seasonal variability of ground water
contamination.
At a minimum, five years of monitoring will be performed to confirm that no
unacceptable exposures will occur in the future. The ground water.
monitoring will provide a better understanding of contaminant distribution
and rate of ground water flow. See Figure 8 for existing ground water
monitoring well locations. A subset of these monitoring wells will be
selected as ground water monitoring points. Surface water and sediment
samples will be taken from the west branch of the Passumpsic River and the
drainage swales of the Dump to confirm that future surface runoff does not
represent an unacceptable threat to the environment. Surface soil samples
will be taken from any new area of surface soil which may be exposed as a
result of movement of the debris mass of the Dump. Due to the low
concentration of contaminants at the Site, the analytical methods that will
be used for ground water and surface water must be capable of achieving
very low detection limits (approximately 1 ppb). The estimated net present
worth of the five-year monitoring program would be $292,000, assuming a ten
percent discount rate. Annual monitoring costs are expected to be
approximately $77,000.
.IX. DOCUMENTATION OF NO SIGNIFICANT CHANGES
EPA presented a Proposed Plan (preferred alternative) for
remediation of the Site on April 10, 1992. The Proposed Plan described
EPA's decision to pursue no further action at the Darling Hill Dump site.
No significant changes have been made to the No Action decision described
in the Proposed Plan. .
x. STATE ROLE
The Vermont Department of Environmental Conservation has reviewed the
various alternatives and has decided not to concur with the EPA No Action
decision.
-------
-------
z
Darling Hill Dump Site Map
Nole: Base map developed from the Draft Remedial Investigation Report.
Oc:Iober. 22. 1991: Environmental Science & Engineering, Inc.
9{
Vermont
Caledonia County
~
e
.~
tl
.~
~
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t::
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'Si
f6
o
I e PW-1 Public Well and Number I
O$~
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o~t\\'ro~
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a
~
~
S
'€
s
((
Lyndonville
Municipal
Well Field
o
I
400
800
. Scale in leel
-------
~
'.
Darling Hill Dump.
Schematic Cross-section Showing
Detection of Contaminants in Soil
>-zj
H
GJ
~
tr:1
N
VOCs Metals
PAHs PCBs
Pesticides
Surfical Soil
VOCs Metals
PAHs PCBs
20
40
Metals
60
80
100
120
140
Depth
(feet)
-------
Migration of
Organic Contaminants
Note: Base map developed Irom the Draft Remedial Investigation Report.
Odcber, 22. 1991; Environmental Science & Engineering, loe.
9{
-wI! Areas where drinking water
IIILfJ standards were exceeded
e PW-1 Public Well and Number
b
/J
~
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.#
u
~
c:
.~
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8
Darling Hill
. Dump
0&6
~\\\ ~
Q&t\\(\~
~
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-
~
::i
'f
s
Q:
Lyndonviile
Public Water
Supply Wells
o
.
400
eoo
Scale in leel
.
-------
..
t8
"1j
~
~
Cross-section Showing Relationship Between Contaminant Plume
and Drinking Water Wells and Approximate TCE Concentrations
A
I
fl~
~
lIt
Q.
NE
9"
,f
~
~
~
-------
Estimated Excess Cancer Risk Levels
Associated with Organic Contaminant Plume
Note: Base map developed from the Draft Remedial Investigation Report,
Oc:Iober, 22, 1991: Environmental Science & Engineemo, Inc.
9{
I!II!IIII1W Areas where drinki.ng water
IIIIIIIiliill standards were exceeded
~
e
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~
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-g
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e PW.1 Public Well and Number
Darling Hill
Dump
b
8
~
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Q:
Lyndonville
Public Water
Supply Wells
o
.
400
800
Scale in feel
-------
,.
"Xj
~
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Cross-section Showing Relationship Between Contaminant Plume,
Drinking Water Wells, and Associated Cancer Risk Estimates
A
I
/
.f
~~
0.
NE
.f
/
~
~~
cl
A'
sw
,j
X' ~..
~:..c, "
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Approximate
Debrl. Mas.
;::.
J
......
I::
.2
I
ii1
o 400
I I
Horizontal Sc:&Ile
.
-------
': -:. !.,~:..'.'-
" I"
Darling Hill Du
mp Contour Map
CROSS SECTJ
ON 8-8'
Note: Adapted I
Dece rom F" Igure E 2
. mber 20. 1991; ~~~n~t F~asibil~y Study A
ental Science & c_,:port
......"Ineering, Inc.
FIGURE 7
20
40
60
-------
Monitoring Well Locations
Note: Base map developed lrom the Draft Remedial Investigation Report,
October, 22, 1991; Environmental Science & Engineering, loe.
9{
e PW-1 Public Well
and Number
101 . Monitoring Well
and Number
107
.
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Scale In feel
-------
-------
.J ,;,.
~.
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State of Vermont
Dc",., \.lIt." of r .,h ftnc1 \'VihJhtt!
. D"P,,,,",en' 01 1=0"'.11. Pn,k. .,,,1 H~,c.tjon
[).D~"me"t g~ ~.,v.'onmft"t31 C:unl.:,,,,,tiO.'
tit..t. ~.nID"i.\ .
1\;,-"".. RVUH,,.C.' <';nnSftrvDtIQt1 ~u...m.I'
AGENCY OF NATURAL RESOURCES
Departmrnt or Environmental Con5C!rvation
Ha7.arclnua Material, Ma"'8omclli Di".
103 South Main SlrtWW", Sulldin,
Waterbury, vr OS671.0404
(110') 2"-11701
June 23, 1992
Mr. Merrill Hohman, Director
U.S. EPA
Waste Management Div. (HAA-CAN2)
. JFK Federal Bldg.
Boston, MA 02203
RE:
Record of Decision - Darling Hill Dump, Lyndon, Vermont
Dear Mr. Hohman:
We have worked very closely with EPA throughout the entire
superfund process on the Darling Hill Dump site, and we
appreciate EPA's considerable efforts to provide us with
opportunities for involvement in the process.
Based on our close involvement, we understand the basis for EPAls
No Action Record of Decision. Based on EPA's interpretation of
CERCLA and the National contingency Plan, as well as EPA policy
regarding use of the fle~ible ma~imum risk level as a basis for
remedial actions, EPA has concluded that there is no basis for
action under CERCLA. EPA has not concluded however, that there
are no remaining environmental, health, or safety concerns
associated with this site.
.
We have several concerns which will not be addressed by EPA's
Record of Decision. These concerns include site closure, long-
term monitoring, institutional controls, and periodic reviews.
Because these conoerns will not be addressed, and in order to
protect the state of Vermont's enforcement authority, we reqret
to inform you that we cannot concur with EPA's No Action Record
of Decision for the Darling Jiill Dump.
Again, we appreciate allot EPA's efforts at this site.
sincere y, .
. ~~
El zabeth McLain, commissioner
EM/TM/tm DARLHILL/dhd025
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