PB95-963902
EPA/ROD/R03-95/188
January 1995
EPA Superfund
Record of Decision:
Sussex County Landfill IS
Superfund Site, Laurel, DE
12/29/1994
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United states Environmental Protection Agency - Region III
Superfund Program
Record of Decision
Sussex County Landfill #5 Superfund Site
Laurel, Delaware
December 1994
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RECORD OF DECISION
SUSSEX COUNTY LANDFILL 15 SUPERFUND SITE
DECLARATION
SITE NAME AND LOCATION
Sussex County Landfill #5 Superfund site
Laurel, Delaware
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the
Sussex County Landf~ll .#5 Superfund site (Site) in Laurel, Delaware
which' was chosen in accordance with the requirements of 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 oil and Hazardous Substances Pollution Contingency Plan
(NCP). This decision document explains the factual and legal basis
for selecting the remedy for this Site. The information supporting
this remedial' action decision is contained in the Administrative
Record for this site.
The Delaware Department. of Natural Resources and E~vironmental Control
(DNREC):has concurred with the selected re~edy (see. attached' letter).
DESCRIPTION OF THE SELECTED REMEDY
The selected remedy for the Sussex County Landfill #5 Superfund site
is No Action. A review of conditions at the. site will be conducted at
least every five years in accordance with Section 121(c) of CERCLA and
40 C.F.R. section 300.430(f) (4) (ii) of the NCP, to verify that no
unacceptable hazards are posed by conditions which may then exist at
the site. .
DECLARATION STATEMENT
EPA has determined that no remedial action is necessary at the site to
ensure protection of human health and the environment. Therefore, the
Site now qualifies for inclusion on the Construction Completion List.
.~...
10/~~ 11'7
Date
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DECISION SUMMARY
1.0
site Name. Location and DescriDtion
The Sussex County Landfill #5 Superfund Site (Site), also known as the
Laurel Landfill, is a 38-acre municipal landfill located off Route 494
and approximately 1 mile west of the Laurel Airport in Laurel,
Delaware (see Figures 1 and 2). The landfill was in operation between
May 1970 and August 1979 and during that time accepted municipal and
industrial waste. Waste was disposed of at the landfill in trenches
which were excavated into the native soil. At the start of the
landfiil .operations, waste was disposed of in the extreme southern
portion of the property with disposal progressing toward the northern
property' boundary.. . Waste placed in. the trenches was covered by
. approximately two feet of soil obtained from soii stockpiles generated
during the excavation of the trenches. After the landfill closed in
1979, a transfer station for municipal waste was operated under permit
from Delaware Department of Natural Resources and Environmental
Control (DNREC) on the nOrthwest corner of the property. This
transf~r station closed. in 1993.
The Site is bordered by property used predominantly for agricultural
purposes. However, residential dwellings also exist along the
roadways surrounding the landfill. There are approximately 5,000
people within a three-mile radius of the landfill and this entire
population uses ground water as its .drinking water supply. The
principal stream draining the site is Broad Creek, which lies
approximately two miles north of the Site. A surface water drainage
ditch (the Collins and Culver Ditch) lies approximately 500 feet from
the northeast corner of the landfill and discharges into Broad Creek.
2.0
site Historv and Enforcement Activities
During the 1980s, .several investigations were conducted at the Site by
Sussex County and DNREC to evaluate the potential impacts posed by
contaminants of concern.on ground water and surface water quality in
the vicinity of the site. As a result of these investigations, DNREC
determined that ground water in the vicinity of the landfill had been.
impacted by contaminants coming from the landfill. Ground Water
Management Zones (GMZs) were subsequently developed for the landfill
and approved by DNREC. Three GMZs were established in the area
surrounding the landfill: one of these restricted the installation of
new ground water pumping wells and two of these restricted pumping
rates of any new and existing wells. On August 8, 1988, DNREC and
Sussex County signed a Memorandum of Understanding (MOU) to support
. the development and implementation of the GMZs. .
In 1986, EPA concluded a site inspection which indicated that ground
water in the area of the landfill had become contaminated with
volatile organic compounds (VOCs) and metals coming from the landfill.
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The site was proposed
1988 and was added to
EPA and Sussex County
which required Sussex
and. Feasibility Study
for the National Priorities List (NPL) in June
the list on October 4, 1989. On April 4, 1991,
entered into an Administrative Order on Consent
County to conduct a Remedial Investigation (RI)
(FS) for the site.
During the RI, one offsite residential well was found to be
contaminated with vinyl chloride just above the Maximum Contaminant
Level (MCL). As a result, Sussex County provided this residence with
bottled water. In February of 1993, Sussex County installed a water
treatment system on the well which uses a carbon filter to remove VOCs
as well as ultraviolet light to reduce bacteria levels.
In the Fall of 1993, Sussex County completed the RI which included the
EPA-prepared Human Health and Ecological Risk Assessments. Based on
the results of the RI and the Risk Assessments, EPA determined that a
FS was not necessary to .evaluate remedial alternatives.
3.0
Hiah1iahts of community Participation
EPA released the RI Report and the Proposed Plan for the site for
public comment on August 1, 1994. In accordance with Section 117(a)
of the Comprehensive Environmental Response, compensation and
Liability Act (CERCLA or Superfund).of 1980, as amended by the.
Superfund Amendments and Reauthorization Act of 1986 (SARA), EPA made
these two documents available to the public in the Administrative.
Record maintained at the.EPA Docket Room in Region III; and in the. .
Laurel Public Library, Laurel, Delaware. The notice of availability.
of these two documents was published in the Wilminaton News-Journal on
August 1, 1994. A public comment period on the documents was held
from August 1,1994 to August 31, 1994. In.addition, EPA held a
public meeting on August 10, 1994. At this meeting representatives
from EPA and DNREC answered questions about conditions at the Site and
the remedial alternative under consideration. A.response to the
comments received during this period is included in the Responsiveness
Summary, which is part of this ROD.
. In addition, EPA distributed fact sheets to the community in July 1992
and July 1993 which provided background information and highlighted
the progress of the RI field work. A public meeting was also held in
the community in July 1992 to discuss the scope of the RI field work.
4.0
Scope and Role of the Resoonse Action within site strateav
EPA has determined that no action is presently warranted at the Site
under the Superfund Program based on: 1) the low levels of
contamination detected in the ground water and 2). the risk levels
which were calculated for the Site.
In addition, in accordance with the MOU and a State Notice of
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Conciliation dated August 1994, Sussex County is required to install a
water line which will serve residents downgradient of the landfill and
within the GMZs with public water. The state Notic~ of Conciliation
also provides for the following: 1) a ground water monitoring program;
2) maintenance of the landfill cover to ensure the integrity and
effectiveness of the soil cover and to correct any effects of
settling, subsidence and erosion; and 3) institutional controls which
restrict well installation and/or operation in the GMZs. These
actions should ensure that the Site continues to pose no unacceptable
risks to human health in the future. .
5.0
Summary of site Characteristics
The Site is .situated within the Atlantic Coastal Plain physiographic
province. The Coastal Plain is underlain by a gently seaward-dipping
wedge of unconsolidated and semiconsolidated sediments. . The thickness
of the Coastal Plain deposits ranges from 4,200 feet in the. northern
portion of Sussex County to approximately 7,000 feet in the
southeastern part of the County. .
The S.ite is directly underlain by' unconsolidated deposits of the
Beaverdam Formation. The Beaverdam Formation is the surficial'
geologic unit over much of south-central Sussex County and is composed
predominantly of medium to coarse grained sand with occasional,
localized zones of interbedded clay and. sand. A near-surface
interbedded clay and sand unit is present north of the landfill.. In.
this area, the interbedded clay and sand unit is generally less than
10 feet thick. This near-surface clay and sand unit was also
encountered at well locations in the landfill area. A clay layer with
interbedded sands has been identified at one monitoring well location
(LS-17) at a depth of 58 to 69 feet below ground surface. A similar
stratum, though not nearly of the same thickness, was encountered at
monitoring well LS-13. A map showing the monitoring well locations is
attached (see Figure 3).
Ground water contained in the Beaverdam Formation is the uppermost .
ground water system at the site.' Depth to w~ter measurements from on-
site monitoring wells range from 6 to 18.5 feet below ground surface.
Ground water flow within the Beaverdam Formation is generally in a .
northerly direction with an average lateral flow rate of approximately
255 feet/year. Monitoring well LS-5 is screened in a perched ground
water zone that exists above the near-surface interbedded clay and
sand unit.
Gro~nd water levels and flow direction appear to be minimally affected
by pumping of the Collins irrigation well which is.located to the east
of the Site. In addition, shallow groundwater flow direction does
not appear to be significantly altered by pumping of the Hastings
irrigation well to the west of the site. However, in the deeper
hydraulic zone of the Beaverdam Formation, ground water flow direction
during the use of the Hastings irrigation well was shifted from a
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northerly direction to.a northwesterly direction.
The ground water level data collected during the RI indicate that the
Collins and Culver Ditch is not a discharge point for the ground water
system monitored by the site monitoring wells. However, perched water
that. may exist in the area of monitoring well LS-13 could be
discharging to this ditch.
Ground water samples obtained from onsite and offsite monitoring
wells, residential wells and two irrigation wells during the RI
indicate that ground water is mainly contaminated with low levels (in
the low parts per billion range) of VOCs (see Table 1 and Figure 3A).
Volatile organic ground water. contamination appears to extend
downgradient of the landfill approximately 1,000 feet northward from
the northwest corner of the landfill. Benzene and vinyl chloride were.
the only VOCs that have been detected at concentrations above the .
Maximum Contaminant Level (MCL). MCLs are standards which are
promulgated under the Safe Drinking Water Act and are defined as the
maximum permissible level of a contaminant in water which is delivered
to any user of a public water system. Benzene was detected above the
MCL of 5 parts per billion (ppb) at. two monitoring wells, LD-01 (9
ppb) and LS-03 (24 ppb). vinyl chloride was detected above the MCL of
2 ppb at one downgradient residential well, RW-02 (4 ppb). ..
Barium was detected in one onsite monitoring well (LD-01) at 4.8 parts
per million (ppm) which exceeds the MCL of 2 ppm. In addition, ground
water data indicated.the presence of bery.llium in low levels. .
However, because beryllium was .sporadically detected in a number of
upgradient wells and downgradient wells, beryllium is thought to be
naturally occurring and not likely to be site-related.
The RI soil gas screening results suggest that minimal subsurface
migration of landfill gases has occurred outside the boundaries of the
landfill. In addition, the ambient air samples collected indicate
minimal impact on ambient air quality resulting from the migration of
gases through the landfill cover.
Surface water and sediment samples were collected from four individual
ponded areas which existed on the landfill at the time of the RI (see
Figure 4). An additional three sediment samples were collected from
other areas on the landfill that appeared to be sediment depositional
environments. The sediment analytical data generated from the RI
showed no apparent impacts on sediment quality at the landfill. A few
organic compounds were detected at low concentrations (less than 0.5
milligram/kilogram (mgjkg). Metals analysis of the sediment samples
showed concentrations comparable to background levels or within the
typical range of concentrations found in natural soils. Surface water
quality monftoring data collected from the infrequently ponded areas
on the landfill surface did not indicate the presence of any site-
related organic compounds. Inorganics were detected in the surface
water. However, no comparative background data could be obtained in
the site vicinity to assess the significance of the inorganics in the
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surface water.
The landfill soil cover was found to be composed'predominantly of sand
with minor amounts of clay and silt. The cover ranges in thickness
from less than one foot to approximately three feet. A total of seven
surficial soil samples were collected in qlternating grids of the grid
system established on the landfill (see Figure 5). Three additional
background soil samples were collected from properties surrounding the
landfill. The RI soils data show no apparent impact on surficial
soils quality resulting from the landfill. No significant levels of
organic compounds were detected in soil samples. Metals
concentrations in these samples were comparable to background levels
or within the typical range of concentrations found in natural soils.
According to the soil borings collected during the RI, the thickness
of the solid waste ranges from 10 to 14 feet. The total volumetric
e,stimate of' solid waste at the landfill is estimated to be '
approximately 610,000 cubic yards. Although no significant settlement
of the solid waste was calculated at the landfill based on the RI
elevation data obtained from the landfill settlement points,
subsequent visual inspection of the landfill by DNREC indicates that
there are several areas which exhibit noticeable waste compaction and
settlement, primarily concentrated in the northern sections of the
landfill. Standing water was evident in some of these areas.
, Seventy plant taxa were identified on or around the landfill. They
<;ire arranged in seven distinct communities: deciduous/coniferous
, ,woods, ,doni ferous woods, ,canopied woo,ds, open. herbaceo\,ls uplands,.
panic grass wetlands, wool grass wetlands, and soft rush wetlands.
Two small deciduous/coniferous woods are immediately adjacent to the
east and south of the landfill. The southern corner of the landfill
is occupied by a dense stand of young coniferous trees. The remainder
of the landfill is occupied primarily by an open,' herbaceous, upland
community. A second distinct upland community with an open canopy of
small trees occupies the eastern and northern edges of the landfill.
Small isolated wetlands are present in the upland community. A single,
plant species listed on the Delaware Plants of Special Concern List,
sandrock cress, also known'as small flowered bitter cress (Cardamine
parviflora yare arenicola), was found on the landfill. .
Thirty species of birds, 10 species of mammals, 4 species of reptiles
and amphibians, 5 taxa of benthic macro invertebrates and earthworms
were seen or otherwise confirmed as being on or around the landfill.
Two bird species on the list of birds of special concern from the
Delaware Natural Heritage Inventory were identified on or around the
landfill: the common nighthawk (Chordeiles minor) and the Cooper's
hawk (Accipiter cooperrii). Potentially, 20 other species of birds,
3 other species of mammals and 3 other species of reptiles, all of
special'concern, may visit or inhabit the landfill. '.
Wetlands are scattered, isolated ponded areas of very small size were
identified on the landfill surface from aerial photographs and site
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inspection. These areas exhibit certain palustri~e emergent
classification characteristics.
6.0
Summary of site Risks
6.1
Human Health Risk Assessment
As part of the RIjFS process, EPA prepared a Baseline Risk Assessment
to characterize, in the absence of remedial action (Le. the "no
action" alternative), the current and potential threats to human
health that may be posed by contaminants migrating into the media of
concern. The risk assessment, conducted in accordance with EPA .
protocols, evaluated the constituents found in the various. media at
the site and determined which are site-related contaminants of concern
..to human health. The risk assessment also evaluated the likelihood of
contact with these contaminants by humans. The concentrations of the.
contaminants, at the points of exposure, were then used to estimate
the potential for adverse effects on human health.
The risk assessment proce~s is composed of four steps: Identification
of the Chemicals of Concern, the Expo~ure Assessment, the Toxicity
Assessment, and Risk Characterization. Each of these steps is fully
described in the Baseline Risk AsseSsment.
6.1.1.
Chemicals of Concern
. .
Chemical selection is based on toxicity, concentration, mobility,
persistence, frequency of detection, likelihood of association with
activities at the Site, laboratory contamination and background
concentrations. The following constituents were selected as chemicals
of concern in the media of concern (ground water) at the site (also
see Table 2):
Residential Wells
Benzene
Vinyl Chloride
1,2-Dichloropropane
1,4-Dichloroben~erie
Monitorinq Wells
Benzene
Vinyl Chloride
1,2-Dichloropropane
1,4-Dich~orobenzene
Trichloroethylene
Beryllium, which was also reported.at risk-based concentrations of
concern, was not considered to be a site-related contaminant. Risk
due to beryllium was assessed since it does contribute to the total
risks of receptors at the Site. Other inorganic constituents were not
determined to be of toxicological significance and wer~ therefore not
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determined to be contaminants of concern.
6.1.2.
Exposure Assessment
The objective of the exposure assessment is to estimate the amount of
each chemical of potential concern at the site that is actually taken
into the body (i.e. the intake level or dose). This is done by
1) evaluating potential pathways by which'populations may be exposed
under current or potential future land use conditions; 2) identifying
concentrations of chemicals in environmental media at potential
exposure points; and 3) deriving concentration estimates using
available analytical data.
.6.1.2.1.
Ground water
Through screening and evaluation of the Site-media data, EPA
determined that the only route of eXposure of toxicological
significance at the Site is through ground water. Contaminants from
the landfill are thought to have migrated to the ground water. The
residents are then potentially exposed to the contaminated ground
water through the consumption of drinking water and household
activities such as showering, bathing, etc. The means of this
exposure are expected to occur in both current and future residential
use scenarios.
Adult receptors may come into contact with contaminants .of concern in
the ground water through the ingestion of contaminated water and the.
inhalation of volatile compounds during showering. While adults may
also come into dermal contact with contaminants during showering,
screening indicates that the risk associated through this pathway is
insignificant for adults. Children may come into contact with
contaminants of concern in the ground water through the ingestion of
contaminated ground water, the inhalation of volatile compounds during
bathing and due to dermal contact with the contaminants during
bathing.
Residential Well:
Residential well RW-2 was used as the point of residential exposure
since it was the only residential well in which contaminants related
to the Site were detected. EPA determined this exposure to be
applicable to both current and future use scenarios for residents
using ground water at Residential Weli RW~2. In addition, exposure
point concentrations are applicable in a future residential scenario
if the contaminants detected in. this well were to migrate to other
residential wells in the vicinity of the Site. .
The Rea'sonable Maximum Exposure' (RHE) which' is defined as the 95t;h
percent upper confidence limit value of the arithmetic mean is used as
the exposure point concentration value for all appropriate risk
calculations. In cases where the RHE value exceeds the maximum
reported concentration for a given contaminant, or in cases where the
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data set is not sufficient for the calculation of an RME value, the
maximum reported value is used for exposure point calculations. If a
contaminant has been determined to be present in samples for a given
medium, but is reported as a non-detect for a given sample, one half
of the detection limit is used in RME calculations for that
contaminant.
As stated above, EPA determined through risk-based screening that
benzene, 1,4-dichlorobenzene, 1,2-dichloropropane, and vinyl chloride
represent contaminants of concern at RW-2. The maximum concentrations
of these selected contaminants of concern were used as exposure point
concentrations since the 95th percent upper confidence limit values
exceeded the maximum contaminant concentrations because of the limited
data set. The exposure point concentration as detailed in the
Baseline Risk Assessment for these contaminants are 4 ppb for benzene,
4 ppb for v~nyl chloride, 2 ppb for l,2-dichloropropane and 1 ppb for
l,~-dichlorobenzene. As previously.indicated, beryllium is not
considered to be Site-related, but is still evaluated in the risk
assessment. The highest concentration of beryllium reported in a
residential well at the site was 2.9 ppb in RW-33. This concentration
was used to represent the upper range of risk posed by beryllium to
site residents.. .
Monitorinq Wells:
Monitoring well exposure point concentrations were used to assess the
exposure of offsite receptors to ground water in.a future use. . .
. scenario. f1onitoring wells LP-l, LS-7R.and LS-16 represent the center
of the organic contaminant plume that was considered .to be the source
of exposure to receptors if the contaminant plume were to migrate to
some offsite point where this water may be used for residential
purposes. It should be noted that this water is not currently being
used by residents.
The exposure point concentrations for the monitoring well contaminants
of concern as detailed in the Baseline Risk Assessment are 9 ppb for
benzene, 1 ppb for 1,2-dichloropropane~ 4 ppb for 1,4-dichlorobenzene,
2 ppb for trichloroethylene, and.2 ppb for vinyl chloride. These
concentrations represent the maximum contaminant concentration since
the 95th upper confidence limit values for this monitoring well group
exceeded the maximum contaminant concentration values. The exposure
point concentration for beryllium is 5.8 ppb which is the maximum .
value detected in any monitoring well (LS-09).
6.1.2.2.
Soils
EPA determined through preliminary screening that soils are not a
significant contributor to site risk. The exposure of receptors tq
.onsite. soils is limited due to the vegetative cover on the landfill
and the prohibition on building on the landfill in the future.
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6.1.2.3.
Surface Water
Because surface water consists of small areas of
that evaporate or drain into the surface after a
surface .water is not considered to ~e of concern
Baseline Risk Assessment.
ponded rain water
short period of time,
for purposes of the
6.1.2.4.
Sediments
Sediments are not thought to be of toxicological significance at the
site.
6.1.3.
Toxicity Assessment
A toxicity evaluation
conducted in order to
and chronic reference
compared.
of the chemicals present at the Site was
identify relevant carcinogenic potency factors
doses against which daily intake levels could be
Slope factors (SFs) have been developed by EPA to estimate excess
lifetime cancer risks associated with exposure to potentially
carcinogenic contaminants of concern. SFs are multiplied by the
estimated intake of a potential carcinogen to provide an upper-bound
estimate of the excess lifetime cancer risk associated with exposure
at that intake level. The term "upper bound" reflects the
conservative estimate of ~he risk calculated from the SF. Use of this
.approach makes.underestimation of the actual .cancer risk highly
unlikely. Slope factors are derived from the results of human
epidemiological studies or chronic animal bioassays to which animal-
to-human extrapolation and uncertainty factors have been applied
(e.g., to account for the use of animal data to predict effects on
humans). SFs for contaminants of potential concern at the Site which
contribute to the carcinogenic risk are presented on Table 3.
Reference doses (RfDs) have been developed by EPA for indicating the
potential for adverse health effects from exposure to contaminants of
concern exhibiting noncarcinogenic effects. RfDs are estimates of
lifetime. daily exposure levels for humans, including sensitive
individuals. Estimated intakes of contaminants of concern from
environmental media (e.g. the amount of a contaminant of concern
ingested from contaminated drinking water) can be compared to the RfD.
RfDs are derived from human epidemiological studies or animal studies
to which uncertainty factors have been applied. RfDs are also
summarized for contaminants of potential concern at the Site on
Table 3. .
6.1.4.
Risk Characterization
For carcinogens, risks are estimated as the incremental probability of
an individual developing cancer over a lifetime as a result of
exposure to the carcinogen. Excess lifetime carcinogenic risk is
calculated by multiplying the dose by the cancer SF. These risks are
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probabilities that are generally expressed in scientific notation
(i.e., 1.0 X 10-4 or 1.0 E-04). An excess lifetime carcinogenic risk
of 1.0 E-06 indicates that an individual has a one in one million
chance of developing cancer as a result of exposure to Site-related
contaminants over a 70-year lifetime under the specific exposure
conditions 'at the site. .
The potential for adverse noncarcinogenic health effects as a result
of exposure to a singe contaminant in a single medium is expressed as
a hazard quotient (HQ) or the ratio of the estimated daily intake of a
contaminant in a given medium to the contaminant's RfD. The hazard
index (HI) is obtained by adding the HQs for all of the contaminants
in a medium or by adding the HQs for all media to which a given
population may reasonably be exposed. The HI provides a useful
reference point for gauging the potential significance of multiple
contaminant exposures within a single medium or acro~s media. HI
values that. are greater than 1.0 indicate that adverse health effects
!nay be expected' to occur. .' . .
Residential Well:
For adults, an increased carcinogenic risk of 9.24 E-05 was calculated
for the ingestion.of ground water containing the contaminants of
concern. An increased carcinogenic risk of 2.60 E-05 was calculated
for the inhalation of volatile chemicals during showering. The
combined risks for these two' residential pathways is therefore 1.18 E-
04 which is marginally above the generally acceptable risk level of
1.0 E-04. Risk estimates' for children were calculated to be less than
those estimates for adults. . .
The noncarcinogenic risk calculated for adult exposure to contaminants
in the residential wells was due to the inhalation of volatile
contaminants during showering. The Hazard Index value calculated was
. 1.23 E+OO. This Hazard Index value is marginally above EPA's
generally acceptable risk level of 1.0 E+OO and indicates a potential
for adverse health effects to occur under the residential use .
scenario. Benzene is the major contributor to the noncarcinogenic
risk in this situation.
Adults consuming ground water containing the maximum concentration of
naturally occurring beryllium reported in the residential wells near
the site may be exposed to an increased cancer risk of 1.46 E-04.
Noncarcinogenic risk due to beryllium is insignificant for all
receptors since beryllium is not a significant contributor to the
Hazard Index.
Although the calculations in the risk assessment assume that no
remediation will occur, it should be noted that in 1993 the County
'placed 'a carbon filter on the one impacted residential well, RW-2
thereby eliminating any current exposure of site-related contaminants'
to this resident.
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Monitoring Wells:
If the levels of contaminants identified in the monitoring well
organic contaminant plume were to migrate to some point where
receptors may come into contact with them and use ground water of this
quality for residential purposes at some point in the future, the
resultant increased cancer risk due to ingestion was calculated to be
4.98 E-05. The increased cancer risk associated with inhalation
exposures for this ground water would be 1.68 E-05 for adults. The
total combined increased cancer risk for adults would therefore be
6.66 E-05. The risk to children was calculated to be less because the
exposure route of inhalation during bathing is less than that of the
adult ,inhalation exposure route due to showering. If receptors were
to consume ground water containing the concentration of naturally-
occurring beryllium reported in Monitoring Well LS-09, an increased
cancer risk of 2.93 E-04 for adult exposure is derived.
. .
Noncarcinogenic impacts for adults as evaluated by the Hazard Index
would be 9.13 E-03 for ingestion of this ground water and 2.67 E+OO
for inhalation during showering. EPA calculated a combined Hazard
Index for adult exposure of 2.68 E+OO. Adverse noncarcinogenic
effects may be expected to occur for adults using this water if
exposure to this ground water were to occur in the future.
Noncarcinogenic risk due to beryllium is insignificant for all
receptors since beryllium is no~ a significant contributor to the
Hazard Index.
6.2
E~vironmental Evaluation
EPA conducted an Ecological Risk Assessment (ERA) to evaluate any
actual or potential ecological risk as a result of exposure to site-
related contaminants of concern. The ERA concluded that a negligible
potential exists for impact to habitats onsite and in the surrounding
area.
7.0
DescriDtion of the Selected Alternative- Bo Action
Under the Superfund Program, studi~s conducted at NPLsites
characterize the nature and extent of contamination and determine the
most feasible cleanup approaches. The studies at this site have
indicated that very low levels of contaminants of concern exist. in the
ground water which translate into correspondingly low risk levels.
Based on these levels and in light of the activities being taken by
the State of Delaware and Sussex County which are described below, EPA
is not requiring any action be taken under the Superfund Program.
Although EPA is not requiring any action at this time, there is the
possibility that future releases or migration of contaminants from the
site could warrant additional actions. EPA has determined that .it is
appropriate to monitor this situation by conducting a review of
conditions at the Site at least every five years to verify that the No
Action remedy remains protective of human health and the environment
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in accordance with section 121(c) of CERCLA and 40 C.F.R. section
300.430(f) (4) (ii) of the NCP.
As noted previously, Sussex County, under a Notice of Conciliation
dated August 1994 with the State of Delaware, will be 1) installing a
water line to residents downgradient of the landfill; 2) establishing
a ground water monitoring program; 3) maintaining the integrity and
effectiveness of the vegetated soil cover to correct any effects of
settling, subsidence, and erosion and to prevent precipitation from
eroding or otherwise damaging the cover which prevents direct contact
with the waste material; and 4) restricting well installation and/or
operation in the GMZs.The information generated as a result of the
ground water monitoring program will be reviewed by DNRECand EPA to
ensure that human health and the environment remain protected. This
information will provide" a basis for. determining if additional.
response actions are required in the future. .
8.0
Documentation of No sianificant Chanae
EPA released the Proposed Plan for the Sussex County Landfill #5 Site
for public comment on August 1, 1994. The public comment period
closed on August 31, 1994. EPA reviewed all written comments
submitted during the public comment period and all comments received
during the pub~ic meeting which was "held on August 10, 1994. A
sUmmary of the comments received during the public comment period. and
corresponding responses to these comments "is included in the. .
Responsiveness Summary section of this Record of Decision. Based on
these comments, EPA has determined that no significant change to the
proposed remedy, as originally identified in the Proposed Plan, was
necessary.
12
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TABLE 1
SUMMARY OF VOLATILE ORGANIC CONTAMINATION
DETECTED pURING THE RI IN THE GROUND WATER
SUSSEX COUNTY LANDFILL '5
CONTAMINANT RANGE OF CONTAMINANT RANGE OF
CONCEN- CON CENT-
TRATIONS RATIONS
(ppb) (ppb)
Oichlorodifluoromethane ND-8 1,1- Dichloroethane ND-2
Vinyl Chloride NO-4 cis-l,2- ND..,4
dichloroethene
Benzene NO-24 Trichloroethylene ND-l
1,2-Dichloropropane ND-2* Toluene ND-2 .
Tetrachloroethene ND-.6 Chlorobenzene ND-5
Ethylbenzene ND-17 1 , 3 - and 1,4-Xylene ND-130
1,2-Xyle~e ND-T1 Isopropylbenzene ND-2
Bromobenzene ND-l N-propylbenzene ND- . 8
1,3,5~Trimethylbenzene .. 1,2,4- ND-8
ND-3
Trimethylbenzene
Sec-butylbenzene ND-.4 1,4-Dichlorobenzene ND-4
1,2-0ichlorobenzene ND-I 4-Isopropyltoluene ND-I
Naphthalene NO-7* Chloroethane ND-4*
Trans-l,2- ND-. 07.* Trichloroflouro- ND-.2*
dichloroethene methane
l~l,l-Trichloroethane. . ND-. 1*
NO = Not Detected
* = Estimated value
13
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Table 2
contaminants of Concern
Sussex County Landfill '5
RES~DENTIAL WELL
Benzene
1,4-Dichlorobenzene
. "".. . ....,. .
'..' .' ....... ..
. ...... ".
. ........ ..' "...........
. . ,..... .... ... <0..
..........rA~~.......
#t:a.~i!<;:fi~)..
43
1,2-Dichloropropane
Vinyl Chloride
1
2
5 0
75 75
5 0
2 0
4
MONITORING WELLS
Benzene
n" .... ..".." ... .......
.... ....... ...... ......
'....... ....." ........
....... .' n.. ... ..,
M~¥~~##iU... .
...ConceriH)
~~itt.tp.l"
93 .
1,4-Dichlorobenzene
1,2-Dichloropropane
Vinyl Chloride
Trichloroethylene
4
15
25
25
5 0
75 75
5 0
2 0
5 0
1) Maximum concentration refers to the maximum concentration of the
contaminant detected in certain wells as defined by the Baseline Risk
Assessment.
.2). Maximum Contaminant Level (MCL) stands for the maximum permissible
level of a contaminant in water which is delivered to any user of a
public water system as defined by the Safe Drinking.Water Act.
3)
All concentrations are reported in parts per billion (ppb).
4) Maximum contaminant Level Goal (MCLG) stands for the non-
enforceable.concentration of a drinking water contaminant that is
protective of adverse human health effects and allows an adequate
margin of safety as defined by the Safe Drinking Water Act.
5) This value represents one-half of the detection limit at
monitoring well LD-Ol.
14
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TABLE 3
TOXICITY VALUES FOR CONTAMINANTS OF CONCERN
FROM THE BASELINE RISK ASSESSMENT (SEPTEMBER 1993)
SUSSEX COUNTY LANDFILL #5
Cancer Inhalation SF Oral SF Inhalation Rfd Oral Rfd
Compound Group' (mg/kg/dt (mg/kg/dt (mg/kg/d) (mg/kg/d)
Benzene A 2.91 E-02 2.9E-02 1.4286E-04
1 ,4-Dichlorobenzene C 2.3E-01 0.1
1,2-Dichloropropane B2 1.14E-03
Trichloroethylene B2 6.0E-03 1.1 E-2 6.0E-03
Vinyl Chloride A 3.0E-01 1.9E+OO
1) See Table 5 for Cancer Group definitions.
2) "__a indicates that no toxicological data exists
15
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TABLE 4
SUMMARY OF SITE RISKS
SUSSEX COUNTY LANDFILL '5
INCREASED LIFETIME CANCER RISK:
.. ..... U" . . .. .... ..
. .. .n" ...'. .
. . ...... .. . . .... ... .... .. ..".
. ............... . .""...."'" ..
....:trigest.fqf}\ Irihc:Lla.Eiqri<. . .... ...
.,<.,< TotaL'
RESIDENTIAL 9 . 25 E-05 2 . 60 E-05 1 . 18 E-04
WELL
MONITORING 4 . 98 E-05 1 . 68 E-05 6 . 66 E-05
WELL
NONCARCINOGENIC HAZARD INDEX:
RESIDENTIAL-
WELL
MONITORING
WELL
3.02 E-04
1. 23 E+OO
1. 23 E+OO
9.13 E-03
2.67 E+OO
2.68 E+OO
Risk values are calculated for adults coming in contact with ground
water which is contaminated with the contaminants of concern (Table
2) .
16
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Table 5
EPA Categories fer. Potential CaQ, ~
EPA Category Group Description Evidence
Group A Human Carcinogen Sufficient evidence from
epidemiologic studies to support a
causal association between
exposure and cancer in humans
Group B 1 Probable Human Umited eVidence in' humans from
Carcinogen epidemiologic studies
Group 82 Possible Human Sufficient evidence in animals.
Carcinogen inadequate evidence in humans
Group C Possible Human United evidence in animals and/or
Carcinogen carcinogenic properties in short-
term stucfaes
Group D Not Classified Inadeqc 1St evidence' animals
- e ",
Group E No evidence No evidence. in at least two
adequate animal tests' or in both
epideniioIogic and animal studies
.. . - -.
..
..
17
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SUSSEX COUN.TV LANDFILL #5
Site Location Map
Kent.
County
Sussex
County
Susse'x County
Landfill #5
2.5 miles southwest
01 Laurel
-.
FIGURE 1
-------
SUSSEX COUNTY LANDFILL #5
Site Layout Map
.
. . .
...
...
.
.
[!]
." /,.,
Guard House / . ""
I J
I I
. I Laurel l
I Landfill I
I I
I I
I I
I I
r .,..'
/ \
/ I
/ I
/ ,
/ I
/ ,
t I
..... -... I
" ,
',---,
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Cd
~
?Z.
~
~
~
~
LEGEND
£
N
- - - Landfill Boundary
.A Residential Supply Wells
[!J Irrigation Supply Wells
NOT TO SCALE
FIGURE 2
-------
SUSSEX COUNTY LANDFILL #5
Ground Water Sampling Locations
~
~
~
~
~
~.
~
A
36
~
./, 'LS-18
Guard House " ~"'t'8
/ ~'4
I Laurel I
1.5-'~ Landfill I
, /
1.5-17/ /
I LS-3/.
I ./
J.S.2./ I
/' I
I \
I I
/
/ . I
/ I
/ I
/ I
(,. I
..... .... I
.,
'.LS-1 I
'-~
.[!]
.
1.5-15
NOT TO SCALE
A
N
LEGEND
- - - Landfill Boundary
A Residential Supply Wells
@ Irrigation Supply Wells
. Monitoring Wells
FIGURE 3
-------
-- ::!""'" ..,.....,.,..,.--,.- ---.-.- -
....
.- .
(;
~
b.:: 0 9:.,
" .,830
..,0.". ,.,?;.:.....'" 40.47)
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"
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;~i)L~..'~ ~:' ) :
-':4:
~.
..
818-9628
~. :'
""'..
/
.....'''';::-:;
';"".'
f"! f-i
of i !;
f! j I:
il-.fl
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-. ;f I :. I f
!...i- i 1,: / t'
".,.~. L;.~
. .'
~
(NO) (11.47)
WeI Owners
1
2
9
10
13
15
30
31
32
33
LS-1I 0 Moniter Wel Location
~"J
J
4
.""
. ~ ,. : .
30. Irrigation wea Location
1.. Sanped F1esidenIiaI ~ WeI
( ) .Cot........bdtiuol of Total Volatie
Organic ~ (ppb)
(ND) No VdaIie Orgaric ~
Detected
-. App(Mi,i1ateLandfiD Boundary
1.0
600
Scale in Feet
CONCENTRATIONS OF TOTAL VOLATILE
ORGANIC COMPOUNDS IN GROUNDWATER
LAUREL LANDRLL
FIGURE 3A
1~1
"3/2J93
-------
653-9075
=
~ SD-3
SW-3
OSD-7
OSD-6
+
J
ft
SG-70 Sediment Sample Location
SD-t~ Surface Water and Sediment
sW.t Sample Location
- Approximate Landfill
Boundary
1,0
400
Scale In Feet
. SURFACE WATER AND SEDIMENT SAMPLE LOCATIONS
LAUREL LANDFILL
FIGURE 4
8001
11112192
-------
GRID NO.1
(~1).
GRID NO.3
(55-3)
55-16
...
GRID NO. 2
(55-2)
GRID NO. 4
(SS-4)
J
d
;)
/'7A
GRID NO. 7---:r a
(55-7) l'
# 7C 7E
C.O
SS-17
...
653-9076
- Sampling Grid.Outline
1C 0 Sampling Locations for
CompoSIte Soil Sample
tA@ VOC and Composite
Soil Sample Location
55-17 Background Soil
... Sample Location
- Approximate Landfill
Boundary
(S5-2) RI SamPle Designation
for the $ampling Grid
1,0
400
Scale in Feet
SAMPLING GRID AND SOIL SAMPLE lOCATIONS
LAUREL LANDFILL
FIGURE 5
8~1
11/18192
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RESPONSIVENESS SUMMARY
Sussex County Landfill #5 site
Laurel, Delaware
This Responsiveness Summary documents public comments received by
the u.s. Environmental Protection Agency (EPA) during the public
comment period on the Proposed Remedial Action Plan (Proposed
Plan) for the Sussex County Landfill #5 Site (Site). It also
. provides EPA's responses to those comments. The Responsiveness
Summa~ is organized as follows:
A.
B.
Overview
Summary of .Citizens' Comments Received During the Public
Meeting and corresponding Responses
Summary of Written Comments Received and corresponding
Responses . .
C.
A.
Overview
A public comment period was held from August 1, 1994 through
August 31, 1994. to receive comments from the public on the
Remedial Investigation (RI), the Proposed Remedial Action Plan,
and the remedial alternative for the Sussex County Landfill #5
site p~eferred by EPA and the De~aware Department of Natural
Resources and Environmental Control (DNREC). A public meeting
was held on August 10, 1994 at 7:00 pm in the Laurel Fire Company'
Hall in Laurel, Delaware. The public meeting was attended by
EPA, DNREC, Sussex County officials, and local residents. The
transcript of the public meeting is. contained in the
Administrative Record for the Site.
The purpose of the public meeting was to present and discuss the
findings of the RI and to apprise the meeting participants of
EPA's and DNREC's preferred remedial alternative. . A summary of
comments received during the meetipg and written comments ..
received throughout the public comment period are presented along
with a response to each. . .
B.Summarv of Citizens' Comments Received Durina the Public
Meetina and Correspondina Responses
Comments made during the public meeting and corresponding
responses are summarized below:
.One citizen made the following comments #1 through #15.
Public Comment #1: A citizen commented that hazardous substances
of. unknown origin and quantity were deposited in the landfill
(with the exception of the asbestos material reportedly disposed
1
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of by DuPont). This citizen was concerned
how much hazardous waste has migrated from
it has taken to migrate. The citizen made
landfill is like a time bomb waiting to go
that EPA does not know
the Site or how long
the analogy that the
off.
Response #1: EPA has reviewed the County's records regarding
types and quantities of waste disposed of in the landfill. EPA
agrees that is not possible to ascertain the exact type and
amount of wastes and their constituents. However, EPA has been
able to determine through ground water monitoring data gathered
during the RI and previous monitoring data gathered by the County
over the last 10 years what contaminants are migrating from the
landfill, at what levels and at approximately what rates. Low
levels of volatile organic compounds (VQCs) which are typically
associated with waste from municipal landfills were detected in
the ground water downgradient of the site. These contaminants
were detected at concentrations ,in the low parts per billion
(ppb) range and are likely migrating with ground water 'at an
estimated rate of approximately 255 feet per year. Since the
types and levels of contaminants have remained essentially.
constant over the last 10 years, EPA does not view the landfill
as a time bomb waiting to go off. However, the ground water in
the vicinity of the landfill will continue to be monitored. If
levels and/or types of contaminants change such that there is a
threat to human health or the environment, EPA will require
appropriate measures to remed~ate the site.
. . . .
Public Comment #2: The citizen commented'that the state and the
County have claimed that they do not have any money to clean up
the contamination and that the proposed water line does not cure
the problem but instead passes the cost of cleanup to future
generations. '
Response #2: EPA disagrees. The No Action alternative was
selected based on technical considerations including: 1) the low
levels of contaminants detected at the site and 2) the risk
l,evels calculated for the Site and 3) ,in light of the'provisions
set forth'in the, state Notice of Conciliation.' The preferred
alternative was not selected based on cost considerations. In
addition, EPA believes that the No Action remedy in light of the
above stated considerations is protective of human health now and
will be in the future and, therefore, does not pass the cost of
cleanup to future generations.
Public Comment #3: The citizen commented that neither DNREC
nor EPA has authority over existing wells which may be affected
by hazardous contaminants in the future. This citizen also, '
stated that it is the responsibility of the property owner to
have wells periodically monitored for future contamination.
Response #3: EPA disagrees that it has no authority to require
action be taken at residential wells which may become
2
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--
I
contaminated in the future. As stated above, EPA does have the
authority to require evaluation and implementation of future.
remedial actions which may be required in order to .be protective
of human health and the environment. With regard to the
responsibility being that of the property owners to monitor their
own wells for contamination, the groundwater monitoring program
which has been .established in the state Notice of Conciliation
requires the County to monitor any residential well within the
public water service area not hooked up to the water line as well
as certain monitoring wells for a period of no less than five
years. After the five year period, EPA will determine whether
future monitoring is required to ensure protectiveness of human
health and the environment as part of the Five Year Review
process. Therefore, EPA does not believe that it is necessary'
for residents to monitor their own wells for potential Site-
related contamination.
Public Comment #4: The citizen asked what the rate and the
direction of contaminant migration is.
Response #4: The contaminants likely migrate in a northerly
direction with the ground water'flow which has an estimated
average lateral rate of approximately 0.7 feet per day or 2p5
feet per year.
Public Comment #5: The citizen asked what the actual outer
limits of the ~ontaminants are to date and whether the migration
is being monitored at the outer limits and depths.
Response #5: As stated in the above response, contaminants
likely migrate in a northerly direction with ground water. The
northernmost well in which Site-related contamination was
detected is a residential well. which is approximately 1000 feet
north of the landfill and is screened at a depth of approximately
70 to 75 feet. No contamination was detected in wells sampled
north of this residential well and as such this well represents
the outer limit of the contamination. A monitoring program will
be used to track the movement of the ground water contamination
through sampling of a series of monitoring and residential wells
located downgradient of the landfill. These wells are drilled to
different depths. In addition~ some of the wells are located
within the ground water contamination plume and some are located
outside the plume. Therefore, the monitoring data will provide
information on the ground water quality both vertically and
laterally at the outer limits of the ground water contamination
and will also be used to evaluate the trend of contaminant
concentrations over time.
. .
Public Comment #6: The citizen asked if the well restriction
applied only to shallow wells, 50-feet-deep or less, or all wells
regardless of their depth. .
3
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Response #6: According to DNREC, restrictions on well
installation within the No Well Zone of the GMZs apply only to
wells screened in the unconfined aquifer. Wells drilled into the
deeper confined aquifer will be permitted as long as they are
double-cased" to ensure no contaminant migration into the deeper
aquifer. Restrictions in GMZ "A" and "B" (only permitting wells
pumped at less than 10 gpm and 100 gpm~ respectively) also apply
to wells in the unconfined aquifer only.
Public Comment #7: The citizen commented that no cost
information with regard to the water line installation or any
other potential clean-up action was made available for review.
Response #7.: EPA agrees that no cost information was generated
to compare, potential clean up actions. Based on the findings of
the Remedial Investigation (RI) and the Risk Assessment and in
light of the state Notice of Conciliation, EPA determined that
the No Action alternative was appropriate. In this situation, a
Feasibility study (FS) is not deemed necessary to compare
alternatives based on technical merit or cost analysis.
Public Comment #8: The citizen asked what additional
restrictions the state Notice of Conciliation imposes on the
properties within the GMZs, such as restrictions on residential,
agricultural or industrial development.
Response #8: The only property restrictions contained in the
state Notice of Conciliation refer to the construction and use of
the ground water wells. However, additional restrictions such as
zoning may be considered by the County in the future should such
be deemed necessary.
Public Comment #9: The citizen asked what the actual death
causes/rates in the population in the vicinity of the site are
and how the death rate from cancer correlates with that' for the
rest of the state of Delaware.
, ,
Response #9: EPA has' not performed a study of the causes/rates
of death in the vicinity of the Site or tried to correlate death
rates from cancer or any other cause with death rates for the
rest of Delaware. The Remedial Investigation and the
corresponding Risk Assessment are designed to assess what the
potential adverse impacts (carcinogenic and noncarcinogenic) are
to human health and the environment from Site-related
contaminants.
Public Comment #10: This citizen commented that BPA proposes to
remove this Site from the National Priorities List (NPL) thereby
making funds unavailable for future cleanup actions.
Response #10: EPA responded that it is not proposing to remove
the Site from the NPL at this time. EPA will be conducting at
4
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least one Five Year Review prior to assessing whether or not to
propose this site for deletion from the NPL. In addition, as
stated in 40 C.F.R. section 300.425(d) (6) of the NCP, EPA has
discretionary authority to take further action at a deleted Site
if a review indicates that ~he remedy is po ~onger protective.
40 C.F.R. section 300.425(e) (3) states that all releases deleted
from the NPL are eligible for Fund-financed remedial actions
should future conditions warrant such actions. . Therefore, even
- if EPA deleted the site from the NPL in the future, funds could
still be made available for remedial actions should it become
necessary. It should, however, be noted that EPA would first
likely require Sussex County and/or any other responsible party
to fund any necessary remedial action. '
Public Comment #11: The citizen questioned the frequency of the
ground water monitoring.
Response #11: DNREC responded that the ground water monitoring
will continue quarterly for the first year and then semi-annually
thereafter until the first Five Year Review at which time EPA
will review the requirement for further monitoring.
Public Comment #12: The citizen expressed concern that
contaminants may impact residential wells in between the periods
of monitoring.
Response #12: EPA disagrees. There are several monitoring
wells located downgradient and to the north of the landfill.
These wells will serve as sentinel wells as they are located
between the landfill and the downgradient residential wells.
Since the contaminants move slowly in the ground water, it is
anticipated that ground water pontamination will be detected in
the sentinel wells in advance of reaching any non-impacted
residential well. In addition, the downgradient residential
wells should not be utilized once the public water supply is
available (scheduled for June 1995). '
Public Comment #13: The, citizen asked how long the County has
'been monitoring'ground water in the vicinity of the landfill,
and what the data have indicated regarding the levels of the
contaminants in the ground water.
Response #13: The County responded that it has been monitoring
the groundwater in the area since approximately 1980. The levels
of contaminants have remained consistent since that time and are
in the low parts per billion range.
Public Comment #14: The citizen asked why EPA i~ not, '
investigating the source of the beryllium detected in the ground
water. The citizen asked if the beryllium could be one of the
underlying factors for the cancer rate in Delaware being the
highest rate in the nation. '
5
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Response #14: The beryllium is not suspected to be a site-
related contaminant as it was sporadically detected in ground
water samples from wells both upgradient and downgradient of the
landfill. Beryllium is a constituent of some minerals, such as
beryl, that can naturally occur in rocks and' sand. When ground
water comes into contact with the rocks and sand, naturally
occurring beryllium can leach into the ground water.
with respect to the link between beryllium and the cancer rate in
Delaware, EPA is not aware of any study investigating the role of
beryllium in cancer in Delaware.
Public Comment #15: The citizen asked if the public water supply'
will be monitored for the chemicals which are regulated by the
Safe Drinking Water Act; including the chemicals which were'. .
recently added in 1990. The citizen asked who will pay for this
monitoring.
Response #15: The public water system will be expected to
operate within the regulations of th~ Safe Drinking Water Act
which includes monitoring for all regulated chemicals. The.
County responded that the utility company will be required to pay
for the monitoring. Although monitoring may ultimately be passed
down to the users of the system, the utility company is regulated
by the Public Service' Commission and therefore, must get approval
on any in.crease in rates ~ .
Public Comment #16: A citizen asked what the cost of the water
line was to each resident. Several citizens expressed concern
over their monthly water bill (i.e., the water usage rate) and
the fact that maintenance fees may increase in the future. One
citizen stated that he felt it would be a financial hardship.
Response #16: The County responded that it will pay the $400.00
connection fee; however, the residents will be responsible for
their monthly water bill which was estimated to be $20.00.
Regarding an increase in the water usage rates, the County again
responded that the Public Service commission regulates the rates
which may be charged by the utility,. The County also responded
that there may be some cost savings to the residents who would no
longer have the costs associated with 1) power usage for the
pumps on the residential wells and 2) maintenance costs for the
pumps. In addition, the County stated that there may be some
cost savings associated with homeowner's insurance once the fire
protection is installed. However, a cost analysis has not been
performed to determine whether these factors would offset the
$20.00 month+y bill~
Public Comment #17: A resident thought that the local property
values may increase with the installation of the water line.
Response #17: EPA has no response to this comment because it is
6
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beyond EPA's expertise and regulatory authority.
Public Comment #18: Several citizens commented that the Site has
negatively affected property values in the area.
Response #18: EPA does not disagree that the Site may have
negatively impacted property values in the area.
Public Comment #19: A citizen asked about the source of benzene
and whether benzene and the other VOCs were migrating from the
site.
Response #19: EPA responded that benzene and other VOCs most
often com~ from petroleum-based wastes which can be attributable
to everyday household products disposed of in municipal .
landfills. The concentration of contaminants found at this Site
is in the low parts per billion.(ppb) range. Specifically, the
concentrations of contaminants of concern ranged from nondetect
to a maximum concentration of 24 ppb for benzene, 4 ppb for vinyl
chloride, 2 ppb for 1,2-dichloropropane,4 ppb for 1,4-
dichlorobenzene and 1 ppb. for trichloroethylene.
Public Comment #20: A citizen asked at what depths contamination
was detected. Another citizen asked if the monitoring wells are
deeper than the landfill waste.
Response #20: The depths of monitoring wells which showed.
contamination range between 30 to 90 feet below ground surface.
According to the County, the residential well in which
contamination was detected is approximately 75 feet deep. The
majority of the monitoring wells are deeper than the landfill
waste as the depth of the waste is estimated to be 10 to 14 feet
deep and the majority of monitoring wells range in depth from 30
to 90 feet below ground surface.
Public Comment #21: A citizen as~ed if levels of contaminants
would decrease as they moved further away from the landfill.
Response #21: EPA responded that the levels of contaminants
would be expected to decrease further away from the landfill due
to dilution, volatilization and microbial degradation of the
contaminants. .
Public Comment #22: One citIzen asked if the contaminants have
migrated downward into deeper wells.
Response #22: The predominant direction of ground water flow in
toe aquifer beneath the Sit~ is horizontal. However, in some of
the monitoring wells, 70 feet deep or greater, contaminants were
detected in low levels. Low level contamination in the deep
. monitoring wells may be the result of seasonal pumping of the
agricultural wells. However, overall the highest concentration
7
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of contaminants were detected in wells that are 50 feet deep or
shallower.
Public Comment #23: A citizen asked what other remedial options
could be considered at the Site.
Response #23: As indicated in response #7, EPA considers the No
Action alternative to be protective of human health and the
environment based on the conditions at the site. Therefore, a
Feasibility Study was not deemed necessary to evaluate other
remedial alternatives. However, EPA did discuss during the
public meeting that remedial alternatives which could be
considered for a landfill site warranting such action include: a
landfill cap, a slurry wall, or a pump and treat system for
cohtaminated groundw~ter. "
Public Comment #24: One citizen asked if the risk assessment
evaluated risk to healthy individuals only or to individuals of
.higher potential risk due to health problems.
Response #24: EPA responded that risk is calculated based on
sensitive members of the population (i.e. elderly, children,
persons with a sensitivity to a particular substance).
Public Comment #25:
be installed." .
A citizen inquired when the water line is to
Response #25: The water line construction is currently scheduled
to begin in December of 1994 and end in approximately June of
1995. The County responded that information regarding the
construction of the water line will be mailed to potentially
affected residents in the future. .
Public Comment #26: Several citizens asked whether or not the
existing residential wells would have to be abandoned. The
citizens were concerned about having to pay for water which is
used to water gardens or which is supplied to chicken houses.
Response #26: The County responded that it would require the
residents to abandon their wells to eliminate potential risk.
addition, the County did not believe there were any chicken
houses located in the water line service area.
In
Public Comment #27: One citizen disagreed and stated that there
were two chicken houses on Route 494 in the area.
Response #27: It has been determined that two sets of chicken
houses do exist in the area. However, both are "located within
GMZ "B", where wells with pumping rates of less than 100 gpmare
permitted. . .'
8
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Public Comment #28: Several 'citizens asked when EPA would make
a final decision and whether their comments would be considered
in this decision.
Response #28: EPA responded. that a final decisio~ would not be
made until after taking into consideration the comments received
during the public comment period. EPA would then issue the
Record of Decision (ROD) which would document the final decision
which addresses public concerns in the attached Responsiveness
Summary .
Public Comment #29: One citizen s~ated that it was unfair that
the responses to the comments would be provided with the final
decision. This process does not allow the citizens to rebut
EPA's responses prior to the issuance of the ROD.
. Response #29: Under the current Superfund remedy selection.
process, the Responsiveness S~ary is issued as part of the ROD.
The purpose of the public comment period and Responsiveness
Summary is not to provide immediate responses to each concern
that is raised but to take these concerns into consideration
prior to maki~g any final decision.
Public Comment #30: One citizen believed that the decision had
already been made because the.water .line was already in progress.
. Response #30: EPA responded that the proposal of the preferred
No Action alternative and the installation of the water line .are
independent actions. The County had made an agreement with the
State in 1988 to take certain steps at a number of landfills
which included the installation of a water line at the Sussex
County Landfill #5. The County is now moving forward to
implement these steps which were made enforceable under the State
Notice of Conciliation. The No Action remedy proposed by EPA was
based on an evaluation of site conditions in addition to the
steps being taken under the state Notice of Conciliation. EPA's
proposal. to the community as described in the Proposed Plan is
that no additional Fede~al action is necessary at the site ba.sed
on the~e factors.
Public Comment #31: One citizen inquired if other properties
could receive public water. .
Response #31: The County responded that their contract with the
utility company included only service to residents within the
GMZs. However, if the utility company wanted to exten~ the water
line to other areas, it could do so.
Public Comment #32: One citizen asked if the properties in the
G~Zs could be subdivided once the water line was in place.
Response #32:
The County responded that development would be
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permitted. However, the County would comment on any development
taking place adjacent to the landfill property to ensure
protection of human health and the environment. .
Public Comment #33: One citizen inquired about: deed
restrictions in the No Well Zone of the GMZs.
Response #33: The County responded that deed restrictions have
already been placed on properties within all three GMZs (i.e. No
Well Zone, Zones "A" and liB" which restrict pumping rates).
Public Comment #34: A citizen asked how the public water service
area was dete~ined. He asked why the GMZs were drawn as
concentric circles versus a "V" extending northward from the
landfill. . .
Response #34: The concentric circles which describe the GMZs
were established in 1988 in a Memorandum of Understanding between
the state and the County. If drawn today with the benefit of the
RI data, the GMZs may have been drawn as a "V" extending north of
the landfill versus the more conservatively drawn concentric
circles which include properties to the south of the landfill.
However, the public water service area logically extends to the.
residents downgradient or north of the landfill within the GMZs
and to the two properties on either side adjacent to the landfill
within the No Well Zone along property lines. EPA feels that the
. public water .service area has been drawn appropriately and is.
protective of human health.
Public Comment #35: A citizen stated that he felt that there
was a conflict of interest regarding a particular property which
is directly adjacent to the landfill to the east. The citizen
felt that this property was slated to receive public water
because it was owned by a County Councilman. Another citizen
agreed and felt that properties to the, north of the GMZs,
including his father's property, .should receive public water.
Response #35: The property' in question is located directly
adjacent to the site to the east. EPA and DNREC feel that it is
appropriate to supply this property with a public water supply
regardless of the ownership of the property because of its
proximity to the landfill. In addition, this property was
previously slated to receive an alternate water supply in 1988
under the state Memorandum of Understanding with the County
(during which time. the property owner was not a County.
Councilman). In resJ>onseto supplying public water to properties
nOrth .of the. GMZs, at this time ,. the data do not indicate that
'these properties are in any danger of being impacted by Site~
related contaminants. However, if the monitoring data show that
site-related contaminants are moving north outside the GMZs and
are impacting human health and the environment, EPA will evaluate
or require an evaluation of other remedial alternatives which may
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include extending the water line to other properties.
Public Comment #36: One resident stated that he and his neighbor
had obtained permits from the state to drill wells within the No -
Well Zone. -
Response #36: Following discussions with representatives from
the drilling company which reportedly installed the well in
question, DNREC has determined that contrary to what was -
suggested during the meeting, a well application was not approved
by DNREC for a new well within the No Well Zone. Apparently, a
permit was never applied for by the drilling company as they were
only performing a repair to an existing well. This action does
not require a permit. -
Publ-ic Comment #37: - -One citizen asked if a newly constructed-
home within the public water service area would need to be hooked
up to the water line and who would pay for the hook up.
Response #37: The County responded that the new homeowner would
be required to connect to the water line immediately and that the
new homeowner would be required to pay for the hookup. The
County stated that they would try, however, to work with
individuals on a case-by-case basis if there was an unusual
- circumstance. The County cited the following example. If there
was a lSD-acre parcel and one resident proposed construction in .
the far northwest corner where Site-related contaminants were not
- likely' to occur, the County might con'sider placement of an - .
individual well there.
Public Comment #38: A citizen asked where the well for the
system is to be located.
Response #38: The County responded that the location for the
supply well had not yet been determined. The County has
contacted several different homeowners in the area whose
properties may be used -_for - the supply well.. A well test first
needs, to be ,conducted tp determine the quantity and quality of
water in each location.
Public Comment #39: One citizen commented that h~ thought that
the community was lucky that the contamination was not worse. He
felt that if the contamination was worse, EPA would mandate
Sussex County to spend millions and millions of dollars to clean
up the Site.
Response #39: EPA agrees that if the contamination were worse,-
remediation would have been required which could have been quite
expensive.
Public Comment #40: One citizen commented that not very many
people were present at the public meeting. He wondered if EPA
11
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"-
had received a lot of interest in the Site from the community.
Another citizen stated that he thought one reason for the small
turnout was due to a "a campaign put on by somebody, telling the
television stations to announce that the residents of Sussex
County can breathe a sigh of relief, everything is okay."
Response #40: EPA responded that 60 copies of the Proposed
Remedial Action Plans were mailed to interested local citizens
and community leaders. In addition, EPA placed a full-page
advertisement in theWilminqton News Journal which announced the
public meeting date, time and location. EPA is not aware of any
publicity campaign to dissuade citizens from attending the, public
meeting. EPA did not participate in any television interviews.
12
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C. Summary of written Comments Received and corresponding
Responses
Copies of all written comments received ar~ contained in the
Administrative Record for the Site. The written comments and
corresponding responses are summarized below:
A citizen of Laurel, Delaware submitted two letters dated August
2, 1994 and August 11, 1994 which were received during the public
comment period. Many of the comments in these letters were
raised by this citizen at the public meeting and as such they are
detailed in Section B of this Responsiveness Summary. However,
they are also summarized below for completeness.
citizen Comment #1: "It is my understanding that the purpose ,of
CERCLA and SARA is to clean up hazardous waste sites. This plan
is only an immediate action plan which postpones the actual clean
up. The "cancer" is still there." The citizen commented that,
the proposed plan did not eliminate the source of the'
carcinogens.
Response #1: The preferred No Action alternative was not
proposed in an effort to postpone clean up at the Site. As
stated in Response # 2, Section, B, EPA feels that the No Action
remedy in light of the Site conditions and the State Notice of
Conciliation is protect~ve of human health now and in the future.
EPA agrees that the waste material and therefore the potential
source 'of carcinogens is not being eliminated. However, EPA
feels that it is not practical to remove the waste from the
landfill nor is it necessary to ensure protection from site-
related contaminants.
Citizen Comment #2: Should the site need to be cleaned up at a
future date (i.e. should the contaminants migrate beyond the
public water service area), will EPA Superfund monies be made
available and is this documented in writing?
Response #2:
Summary.
See Response #10, Se~tion B of the Responsiveness
citizen Comment #3: What is the rate of migration of
contaminants from the site?
Response #3:
Summary.
See Response #4, Section B of the Responsiveness
Citizen Comment #4: What are the actual outer limits of the
contaminants to date and is the migration of contaminants being
monitored at the outer limits and depths?
Response #4:
Summary .
See Response #5, Section B of the Responsiveness
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Citizen Comment #5: Does the well restriction apply to only
shallow wells, 50-feet-deep or less, or to all wells regardless
of how deep? Explain and correlate these restrictions to
monitored data..
Response #5: See Response #6, Section B of the Responsiveness
Summary for restrictions. These restrictions appropriately
apply to the unconfined aquifer and are based on the ground water
data obtained during the RI.
citizen Comment #6: Several comments related to the absence of
cost data which would be used .to evaluate remedial alternatives
including the water line. "What are' the life cycle costs for
this plan?" "Should the site need to be cleaned up in 5 years,
what is EPA's estimate of. cost? Compare to 1994/5."
. ,
Response #6:
Summary.
See Response #7, Section B of the Responsiveness
Citizen Comment #7: "By what amount has the value of the
affect~d properties been changed by the migration of
contaminants?"
Response #7: EPA has not performed an analysis of property.
values in the area nor has EPA determined if the property values
have .been affected by the Site.
citizen Comment #8: "Beyond water usage, what additional
restrictions on the properties within the GMZ does this plan
impose, e.g., residential, agricultural, industrial development?
Response #8:
Summary.
See Response #8, section B, of the Responsiveness
citizen Comment #9: "The incidence of health hazards have
empirically calculated. What is the actual death cause
correlation in the population of the vicinity of the 'Site,
" cancer?" . "How does the' death rate correlate with all of
Delaware, e.g. cancer?"
been
e.g.,
Response #9:
Summary .
See Response #9, Section B, of the Responsiveness
citizen Comment #10: The citizen indicated that he felt that the
decision waS previously made because the County was already in
the process of implementing the water line.
Response #10:
Summary.
See Response
#30, 'section B, of the'
Responsiveness
citizen Comment #11: "No references were made to any ecological
studies down stream nor wetland exposure caused by the weeks lonq
14
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flooding of hundreds of acres of land in the vicinity of the
landfill in Jan '94."
Response #11: EPA did perform an Ecological Risk Assessment
which indicated that little; if any,' risk exists for adverse
impacts to ecological habitats onsite or in the surrounding area
from Site-related contaminants. EPA agrees that it did not
perform an analysis of the impact of the January 1994 flooding
which was referenced by the comment.
citizen Comment #12: The citizen commented that future meetings
should be videotaped, so as to more accurately capture the tone
of the meeting. He suggested that a written transcript could be
made from the videotape.
Response #12: EPA agrees that videotaping public meetings is
one way to accurately capture the tone of the meeting. However,
EPA feels that the written transcript of the public meeting and
the Responsiveness Summary which are contained in the
Administrative Record for the Site also capture the tone of the
meeting and accurately represent the concerns of the citizens.
A letter was received on August 31, 1994 from a resident of
Millsboro, Delaware. This letter was sent at the request of
resident of Laurel, Delaware. The comments contained in the
~etter are summarized below: .
a
citizen Comment 13: "..[a citizen] is very concerned about the
plume of contaminated water which is leaching from the landfill
heading towards him and his farm."
Response #13: It is EPA's understanding that the property in
question lies outside the GMZs to the northwest. EPA does. not
believe that any site-related contaminants are approaching this
property. It is not anticipated that Site-related contaminants
at levels of concern would reach a property which is located at
that distance from the landfill. Howeve~,.EPA and DNRECwill
continue' to review the ground water monitoring data to ensure
that Site-relat~d contaminants at levels of concern are not
extending beyond the limits of the GMZs.
."
citizen Comment #14: This citizen commented that she has
trying for the last 19 years to get Sussex County and the
of Delaware.to bring the six County dumps into compliance
the State and Federal laws.
been
State
with
Response #14: -Regarding the Sussex County Landfill .#5, DNREC. .
will require Sussex County under the State Notice of Conciliation
to take certain measures to close the landfill in accordance with
the applicable 1974 Delaware Solid Waste Disposal Regulations to
the extent practicable. According to DNREC, there are some
circumstances which make compliance with these regulations
15
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---.""
impracticable. For example, there exist quite diverse
flora and fauna communities on portions the landfill.
not be reasonable to clear these areas to replace them
feet of soil and seed in an effort to comply with the
regulations. In these areas, the mature vegetation provides a
more effective cover than would the 2 feet of soil and seed.
and mature
It. would
with :2
citizen Comment #15: The letter states "...(a citizen] says that
he has independently tested water samples from nearby wells which
are more severely contaminated than the samples presented by the
County. The County has also refused to allow him access to their
most recent sampling results. This makes all of us very
suspicious and uneasy."
. Response #15: In response to the first issue, EPA has requested
the analytical results from the samples which were reportedly.
taken by this citizen. He has indicated that he does not wish to
release the results unless he can be reimbursed for the cost of
the analytical services.
In response to the County's refusal to allow. access to sampling
results, all sampling results which were relied on for the
selection of the proposed alternative are located in the
Administrative Record for th~ Site which is available for
inspection at the Laurel Public Library. EPA believes that the
"County's most recent sampling results" which are referenced'in
this comment refer to monitoring which was performed by the'
County in August 1994. It is EPA's understanding that the
analysis from this sampling event was not completed at the time
of the request which was apparently made sometime prior to the
date of this letter, August 31, 1994. EPA received the
analytical results from this sampling event on September 29,
1994. These results were then placed in the Administrative
Record for public inspection.
citizen Comment #16: The commentor requested that EP~ postpone
the decision until the "questions arising from.the County
Administration's refusal to' ailow access to their test results
(can] be answered."
Response #16: As indicated in the above comment, EPA has
reviewed the results of the'first round of quarterly monitoring
which were received by the Agency on September 29, 1994. EPA's
review of this monitoring data shows that the levels of
contaminants have remained essentially the same as they were
during the RI and during previous sampling conducted by the
,County. EPA, therefore" feels that ,the No Action alternative is,
still protective of human health and the environment.
A letter was received from a citizen of Laurel, Delaware dated
August 31, 1994. His comments are summarized below:
16
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citizen Comment #17: Several comments were related to various
cancer cases 'in residents within the GMZs.
Response #17: without supporting studies and extensive
epidemiologic data, it is difficult, if not impossible, to
establish a causal relationship between exposure to an agent and
an adverse health effect in a given population. However, because
the cancer cases to which this comment refers occurred in several
different organs in the body (brain, bladder, and kidney), it is
unlikely that a single chemical or limited class of chemicals is
responsible. In addition, Site-related conta~inants have only
been detected in one residential well, not in all the wells.
referenced in this comment.
citizen Comment #18.: The citizen commented that on Exhibit
AR304559 of the Administrative Record, EPA had handwritten the
comment "But Benzene incr." in the margin of this exhibit. This
exhibit is a letter written from the project manager at Roy F.
Weston, Inc. to the EPA project manager on behalf of Sussex
County. The purpose of the letter was to forward to EPA
monitoring results from monitoring well, LD-1.
Response #18: EPA agrees that the concentration of Benzene' as
indicated on Exhibit AR304559 shows an increase from ND
(nondetect) in 1984 to 9.0 ppb in 1992. However, these levels
are all in the low ppb. range and are of the same order of .
magnitude. In addition, EPA used the highest level of 9 ppb in
the risk calculations as documented in the Risk Assessment for
the site even though no one is currently being exposed to
benzene. As stated previously, the ground water monitoring
program, which is detailed in the State Notice of Conciliation,
will continue to monitor Site-related contaminants in LD-l as
well as in other Site monitoring wells. If levels are found to
have increased to a level which would warrant concern and/or it
is determined that there are receptors being exposed to levels of
concern, EPA will require an evaluation of alternate remedial
actions. .' .
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OFFICE OF THE
DIRECTOR
STATE OF DELAWARE
DEPARTMENT OF NATURAL RESOURCES
Be ENVIRONMENTAL CONTROL'
DIVISION OF AIR Be WASTE MANAGEMENT
89 KINGS HIGHWAY
P.O. Box 1401
DOVER. DELAWARE 19903
TELEPHONE: (302) 739 .4764
November 28, 1994
~r. Peter H. Kostmayer (3RAOO)
Regional Administrator
U.S. EPA, Region III
841 Chestnut Building
Philadelphia, P A 19107-4431
RE:
Sussex County Landfill #5 (Laurel) Record of Decision, December 1994
Dear Mr. Kostmayer:.
The Delaware Depanment of Natural Resources and Environmental Control (DNREC) has completed'
its review of the December, 1994 Record of Decision (ROD) document for the Sussex County Landfill
liS Superfund site. This correspondence represents DNREC's official concurrence with the ROD for
the Laurel landfill. As you are aware, DNREC has been actively involved throughout the Superfund
. process' as it pertains to this site. and has been an' integral part. in the development' of the response
actions which directly led to the selected remedy.
We believe that the actions already taken between the State and Sussex County will ensure protection of
public health, welfare and the environment, and are pleased with your agreemem in this matter. We
therefore concur with the "No Action~ remedy selection.
Sincerely, j .
~.u;bv~
Director, Division of Air 3.Ild Waste Management
NADP:KJR/mcb
KJR94164.SSX
DE-OI3 IIB9
cc:
Christophe A.G. Tulou
N.V. Raman
Jamie H. Rutherford'
Keith Robenson
Robert Kuehl
Michael Izzo
'Z'da"~'4. ~ ~ ~ tHe fP'«!
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