PRELIMINARY PUBLIC HEALTH ASSESSMENT
SUSSEX COUNTY LANDFILL #5
LAUREL, SUSSEX COUNTY, DELAWARE
Sussex County Landfill No. 5 is an inactive 35.26-acre landfill
located in Laurel, Sussex County, Delaware, which was placed on
the National Priorities List (NPL) by the U.S. Environmental
Protection Agency (EPA) 
in October 1989. Sussex County operated
a landfill at this location from May 1970 through August 1979.
Mixed industrial and municipal wastes, reported to contain
various organic wastes, were disposed at the site. In 1976, the
site received 1,000 pounds of asbestos waste. Only limited
sampling has been done on-site. One monitoring well just north
of the site was found to be contaminated with several organic
chemicals. Three other monitoring wells had limited organic
contamination. Sixteen of 18 residential wells tested north of
the site had nitrate/nitrite levels above 10 mg/l. Ingestion of
nitrate/nitrite contaminated water with levels above 10 mg/l
would be a health hazard for infants under 1 year old and adults
with less acidic stomachs than normal. The Sussex County
Landfill No. 5 does not appear to be a source of the
nitrate/nitrite contamination. Based on information reviewed,
the Agency for Toxic Substances and Disease Registry (ATSDR) has
concluded that the Sussex County Landfill No. 5 NPL site is an
indeterminate public health hazard. This conclusion is based on
a lack of the data required to evaluate the potential for and/or
the amount of off-site contamination of air, soil, surface water,
sediment, and the food chain. All the private drinking water and
irrigation wells in the three groundwater management zones at the
Laurel Landfill should be sampled. Analysis should be done for
the priority pollutants and the standard water quality
parameters. A more complete evaluation should be made of the
amount of or potential for movement of contaminants off-site.
Samples should be collected as required to assess the potential
for migration of the asbestos on-site.
The Sussex County Landfill No. 5, Laurel, Sussex County, Delaware site has been evaluated for appropriate follow-up with respect to health effects studies by the ATSDR Health Activities Recommendation Panel (HARP). This site is not being considered for follow-up health activities at this time because no exposure to site-related contaminants was identified. ATSDR will reevaluate this site for any indicated follow-up, if data become available suggesting that exposure of humans to site-related contaminants at levels of health concern did or is occurring.
A. SITE DESCRIPTION AND HISTORY
The Sussex County Landfill No. 5 is an inactive 35.26-acre landfill located in Laurel, Sussex County, Delaware (Figure 1) which EPA placed on the NPL in October 1989. Sussex County purchased the property on January 5, 1970, and operated a landfill on it from May 1970 through August 1979. The site is currently used as a transfer station. Mixed industrial and municipal wastes, reported to contain various organic wastes, were disposed at the site. In 1976, the site received 1,000 pounds of asbestos waste from the DuPont Seaford Plant. On December 19, 1984, the NUS Corporation, which was the Region III Field Investigation Team Contractor for the EPA, conducted a site sampling inspection of the site.
The Remedial Investigation/Feasibility Study (RI/FS) Work Plan for the Sussex County Landfill was finalized in August 1991. The ATSDR provided comments on this work plan to the EPA. The Remedial Investigation of this site will begin in spring 1992 and is scheduled for completion in April 1993.
Two separate site visits have been made relating to this site. Ms. Lisa Hayes and Lynn Wilder of ATSDR made a site visit on March 9, 1989.1 Along with staff from the Delaware Division of Public Health (DDPH) and Department of Natural Resources and Environmental Control (DNREC), they toured the site and surrounding area and met with the Sussex County Engineering Department. Dr. John Crellin of ATSDR made a site visit on June 19-21, 1991.2 He collected community health concerns on June 19-20 through participation in a community survey with two EPA Region III staff. Along with Bucky Walters of ATSDR and the two EPA staff, he made a tour of the site on June 20, 1991. The information gathered during these site visits is included in the appropriate sections of this public health assessment.
C. DEMOGRAPHICS, LAND USE, AND NATURAL RESOURCE USE
Information in the recently approved RI/FS Work Plan for Sussex County Landfill No. 5 indicates that there are only 29 domestic wells potentially at risk for contamination from the landfill.3 These 29 wells lie within the groundwater management zones established in an agreement between Sussex County and the DNREC. The groundwater management zone was developed to control and restrict groundwater usage around the landfill. Assuming that there are 3.5 persons per household, there are about 100 people consuming water from the wells in these management zones. There are no public water wells in or near the groundwater management zones.
D. STATE AND LOCAL HEALTH OUTCOME DATA
The DDPH was consulted about available health outcome databases. The Delaware Tumor Registry is the 3rd oldest in the United States and has population-based coverage of the state. The tumor registry data can be analyzed for specific zip codes and cities. The Delaware Birth Defects Registry was started in 1989. Standard mortality and morbidity data are available for Sussex County by zip code and city since 1986.
These databases were not searched since the population with the potential for exposure (about 100) is much smaller than the population in a zip code. This disparity would make it very unlikely that any health effects due to the site could be detected.
Community health concerns were identified through participation in a community survey conducted by EPA and contact with Laurel City and Sussex County officials and the DDPH.2 The community survey included a explanation of the role and responsibilities of EPA and ATSDR at NPL sites, and solicitation of health concerns.
The following health concerns were expressed by those surveyed:
(1) What are the health effects of nitrates and other contaminants found in private wells, especially for children, elderly, and chronically ill? (All the residents interviewed were aware that the nitrate contamination was a county-wide problem and probably not site-related.)
(2) Do safe levels for chemicals (i.e., Maximum Contaminant Levels [MCLs] or other permissible exposure levels) identified in sampling results protect sensitive individuals?
(3) Could the migraine headaches being experienced by some area residents be site-related?
(4) Could there be contaminants in the spray from the nearby irrigation sprinklers and could the use of those sprinklers influence the groundwater flow so that residential wells become contaminated?
(5) Is the latex polymer that Dupont reportedly disposed in the landfill potentially hazardous?
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
The tables in this section list contaminants which have been found in sampling around the site. We evaluate these contaminants in the subsequent sections of the public health assessment and determine whether exposure to them has public health significance. ATSDR selects and discusses these contaminants based upon the following factors:
Environmental sampling around the Sussex County Landfill No. 5 were recently reviewed in the RI/FS work plan for the site.3
The data tables include the following acronyms:
Comparison values are the contaminant concentrations in specific media that are used to select contaminants for further evaluation. These values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevant guidelines. CREGs are estimated contaminant concentrations based on a maximum of one excess cancer in one million persons exposed for 70 years. CREGs are calculated from EPA's cancer slope factors. EPA's Maximum Contaminant Levels (MCLs) represent contaminant concentrations that EPA deems protective of public health (considering the availability and economics of water treatment technology) over a lifetime (70 years) at an exposure rate of 2 liters water per day.
The Toxic Chemical Release Inventory (TRI) database was developed under Section 313 of Title III of the Superfund Amendments and Reauthorization Act (SARA) of 1986. TRI contains self-reported information on chemical releases from manufacturing facilities. ATSDR reviewed available TRI data for 1988 to determine what types of contaminants have been released into the environment in Sussex County and whether any of those releases occur near the site. A total of twelve industries reported releases of 181,999 pounds to the air and 11,327 pounds to the water in 1988. The chemicals being released included biphenyl, chloride, formaldehyde, phosphoric acid, sodium hydroxide, sulfuric acid, propylene, ammonia, acetone, styrene, nitric acid, dibenzofuran, friable asbestos, zinc, and manganese. None of these releases occurred near Sussex County Landfill No. 5 site.
The location of sampling points and monitoring wells is indicated on Figures 2 and 3. Sampling of groundwater, especially for organic compounds has been concentrated on the wells north of the landfill. Two of these, LD-1 and LS-4 are located just north of the boundary of the site. Because the groundwater flow appears to be northward, ATSDR considers LD-1 and LS-4 to be adequate indicators of on-site contamination. The monitoring results for these wells are described in the Off-Site Contamination section and Table 1 (Appendix One).
Water and leachate were collected in two 10 foot wide, six inch deep depressions or ponds at two areas on-site (Figure 2).4 Water samples collected from these ponds contained chromium (8.2 ug/l), mercury (2.3 ug/l), nickel (18 ug/l), and silver (13 ug/l). Sediments from these on-site ponds contained 4-methylphenol (1,880 ug/kg) and toluene (940 ug/kg). A photoionization detector revealed levels of organic chemicals in the air at casings and sink holes just above a detection limit of 1 ppm, but nothing six feet above the casings and sink holes. Soil sampling data and information on the disposal of the asbestos waste were not identified in ATSDR's review.
There are 11 monitoring wells north of the site (Figure 3). Samples have been collected from some or all of these wells on a number of occasions.3 As indicated in Table 1 (Appendix One), the well labeled LD-1 was found to be contaminated with a number of organic chemicals in 6/6 samples. A single chemical was detected in wells LS-7, 10, and 12 on one occasion. Two chemicals have been found in LS-13 on separate samplings.
The locations of the domestic wells north of the landfill are depicted in Figure 3. These wells were sampled in August 1989, and April and October 1990 for volatile organic compounds, nitrate/nitrite, and several water quality indicators. The well labeled number 2 in Figure 3 has been found to have low levels of several organic compounds (Table 2, Appendix One).
Five of the 11 monitoring wells and 16 of 18 residential wells have nitrate/nitrite levels which exceed EPA's maximum contaminant level (MCL) of 10 mg/l. Nitrate/nitrite levels in all 11 of the monitoring and 17 of 18 residential wells were above the detection limit of 1 mg/l. The highest level found was 23 mg/l.
Sampling of residential wells in 1984 found four wells with levels of cadmium and mercury above the EPA MCL for these metals.4 However, these results were considered to be of questionable validity based upon the quality assurance review of the data.4 The results were not confirmed in later samplings. These four wells are located to the north, south, east, and west of the site. Three of the four are not in the path of the groundwater flowing north from the landfill (Figure 4).
Off-site surface water samples were not collected. Contaminant concentrations present in upstream and downstream sediment samples are presented in Table 3 (Appendix One).
Sampling of soil, air, and other media off-site have not been done.
C. QUALITY ASSURANCE AND QUALITY CONTROL
Data qualifiers were assigned to many of the reported contaminant concentration values.4 The reliability of these data will affect the validity of the conclusions and recommendations of this preliminary public health assessment.
The site is only partially fenced, thus access is not restricted. There has been some unauthorized dumping (empty drums and old appliances) of wastes that might pose physical injury hazards.1,2,5 During the site visit in 1991, evidence of unauthorized entry such as cutting of Christmas trees and target practice were identified.2
A. ENVIRONMENTAL PATHWAYS (FATE AND TRANSPORT)
The waste buried in the landfill is estimated to be 12 feet thick. Waste material is in contact with the ground water and sampling data for the monitoring wells generally indicate that leachate from the waste has penetrated into the aquifer to a depth of at least 50 feet (the depth of LD-1) with limited movement down to 90-95 feet. A leachate plume extends an estimated 400 to 500 feet down-gradient (north) of the landfill. Groundwater flow does appear to be northward from the site (Figure 4) at an estimated rate of 311 feet/year. Available monitoring data indicate that the flow is predominantly horizontal/lateral.
The site is underlain by the Columbia Formation, which is a coarse sand and gravel formation, with segregation of pebbles into bands. The Columbia Formation is underlain by the Manokin Aquifer, which is a medium coarse sand that frequently contains small gravel. These units are hydraulically connected and apparently are unconfined. Within a 3-mile radius of the site, there are 703 domestic wells and 3 municipal wells which utilize water from either the Columbia Formation or the Manokin Aquifer.
All wastes disposed during landfilling operations have received a final cover of 2 feet of soil. Some unauthorized dumping of nonhazardous solid waste has apparently occurred since the site was closed.
Two small, shallow on-site ponds or depressions receive precipitation runoff and contaminated leachate. Surface water runoff and sediments from the site enter Culver Ditch, which drains into Broad Creek, which in turn enters into the Nanticoke River (Figure 1).3 Broad Creek is used for fishing and swimming. The Nanticoke River is used for sport fishing. Although Culver Ditch is dry most of the time, surface water and sediment entrained contaminants may migrate off-site via this pathway. A sediment sample collected upstream of the point where runoff from the site enters Culver Ditch indicates that agricultural activities in the area may be responsible for some sediment contamination. However, samples collected downstream of the site (see Table 3) indicate that some sediment contamination may be attributable to the site. Additional sampling is necessary to address this issue.
Many of the contaminants found at the site are volatile organic compounds and they have been detected around well casings and in sink areas at the site, but not six feet above the ground.4 Thus, it is unlikely that appreciable concentrations of these contaminants will leave the site. However, off-site air monitoring is needed to confirm this.
Contaminants leaving the site via ground water, surface water, sediments, and air may be taken up by food chain entities present on and around the site. Ground water containing contaminants may be used for irrigating crops or watering livestock, contaminants dissolved or suspended in surface water may be translocated along with contaminants adsorbed to sediments to areas where fish or other consumable aquatic animals live, and contaminants may volatilize from soil or be resuspended in air and carried from the site where they are deposited on plants or inhaled by animals.
On-Site
There is no known on-site exposure to the contaminated ground water under the site. Remedial workers could receive inhalation and dermal contact exposures to contaminants in the water, if ground water is pumped from the ground and treated. However, the concentrations of the contamination are low and exposures would be infrequent and of short duration. Therefore, they are unlikely to be of public health concern.
Available data indicate that the material used for final cover of the wastes was not checked for contamination. Therefore, localized areas of contamination may exist. Soil sampling will be necessary to address this issue. The only uncovered waste remaining on-site is believed to be nonhazardous solid waste (empty drums and old appliances).
Access is not restricted, because the site is only partially fenced. Trespassers entering the site and wading in the depressions may receive inhalation, ingestion, and dermal contact exposures to contaminants present in them. Contaminant concentrations in water and sediment in the ponds or depressions are low and contact with the contaminants should be infrequent and of short duration. The two small, shallow ponds or depressions that accumulate leachate and precipitation do not pose a potential drowning hazard. Thus, the leachate collection ponds do not pose a physical or health hazard.
No evaluation of the food chain pathway could be made, because of the lack of data on contaminants in animals and plants on-site.
Off-Site
The individuals using residential well 2 (Figure 3) are being exposed to low levels of 1,1 dichloroethane, trans-1,2-dichloroethene, 1,2-dichloropropane, trichloroethene, and benzene. The users of 16 wells north of the site are being exposed to nitrate/nitrite levels above EPA's MCL of 10 mg/l.
Residential well 2 has low levels of organic contaminants. This well draws water from the same formation as off-site monitoring well LD-1 which has also consistently been shown to have low levels of organic contaminants. Residential well 2 lies directly down-gradient from LD-1. However, only two of the four monitoring (LS 4-7) and one residential well (9) that lie between LD-1 and residential well 2 have shown any contamination and this was one chemical one time. Therefore, it is not certain that the landfill is the source of organics contamination in residential well 2. Every home around the site has its own on-site sewage disposal system (septic system) so this would be another possible source for contamination of residential wells.
Seventeen of the 18 wells sampled north of the landfill are contaminated with nitrate/nitrites. Sussex County and DDPH indicated that nitrate/nitrite contamination is common in shallow residential wells in Sussex County.2 The mostly likely sources of the nitrate/nitrites are poultry production and other types of agriculture.
Sussex County samples the 18 residential wells every six months. Every household in the "no well" area of the groundwater management zones will be given the opportunity to hook up to a public water system the county will be installing.5
Off-site soil samples were not collected. Thus, it is not known if persons living, working, or playing in the area immediately surrounding the site are receiving ingestion, inhalation, or dermal contact exposures to off-site soil contaminants.
Surface water and sediments leaving the site may contain site contaminants, and thus represent a potential source of exposure. There has been no sampling of off-site surface water samples. Off-site sediment sampling data are inadequate to determine if contaminants present in off-site sediments are attributable to the site or to agricultural activities in the area.
Data describing the occurrence of game and non-game food chain entities on and around the site were not identified in ATSDR's review. Therefore, the potential for site-related contaminants to be taken up by off-site food chain entities and subsequently ingested by humans cannot be addressed.
As discussed in the preceding sections, the data available to ATSDR indicate exposure of humans to organic chemicals and nitrate/nitrites is occurring in wells immediately north of Sussex County Landfill No. 5. Low levels of a variety of organic compounds have been found in one residential well and a single chemical in another. As indicated in Table 2, only the levels of 1,1-dichloroethane and 1,2-dichloropropane exceed the appropriate comparison values. Seventeen of 18 residential wells had detectable levels of nitrate/nitrite and in 16 the levels were above the EPA MCL of 10 mg/l. The Toxicological Evaluation portion of this section will review the health effects possible from exposures to nitrate/nitrites, 1,1-dichloroethane, and 1,2-dichloropropane. In addition, the community concerns will be addressed. As discussed in the State and Local Data Section, health outcome data were not obtained.
As will be discussed, drinking the nitrate/nitrite contaminated water from the 16 wells with levels above 10 mg/l would be a health concern for infants less than a year old and adults with less acidic stomachs than normal.6 Exposure to 1,1-dichloroethane and 1,2-dichloropropane at the low levels found in residential well 2 does not represent a health hazard.
Only one health effect, methemoglobinemia, has been documented in humans or animals exposed to nitrate.6 Except for methemoglobinemia, extensive studies of rodents found no evidence of birth or reproductive effects nor any systemic effects, even at doses over 1100 parts per million (ppm). Several epidemiological studies of human exposures reveal similar results.
Methemoglobinemia due to nitrate exposure occurs almost exclusively in infants less than one year old.6 Methemoglobin is a type of hemoglobin and, unlike normal hemoglobin, is unable to carry oxygen. Too much methemoglobin causes the lips and skin to turn blue and can lead to weakness, rapid pulse, and, eventually, death.
Nitrate is converted to nitrite by certain bacteria in the stomach.6 When nitrite enters the blood it causes the formation of methemoglobin. Only small amounts of nitrate are converted to nitrite in the normal human because the number of those certain bacteria is low. Large numbers of those bacteria occur only when the stomach is less acidic than normal. This less acidic condition is usually found only in infants whose primary source of food is milk (usually children under one year old). Rarely, this less acidic condition is found in adults. For infants and adults with less acidic stomachs, the safe level of exposure to nitrates is 10 ppm.6
Significant environmental exposure to nitrates appears to occur only through drinking water or formula contaminated with nitrates.6
Exposure to the highest levels of 1,1-dichloroethane (2.6 ppb) and 1,2-dichloropropane (1.4 ppb) found in residential well 2 does not represent a health hazard to the users of this well. These two chemicals are considered carcinogens based on studies in animals. They were selected as contaminants of concern using comparison values based on an additional risk of cancer of 1 in one million after 70 years of exposure.6 Exposure for those using residential well 2 would be less than 70 years based on the extent of the contaminant plume, the groundwater flow rate, and the pending connection to a public water supply. This results in a maximum additional risk of cancer less than 1 in one million.
B. EVALUATION OF COMMUNITY HEALTH CONCERNS
The concerns listed in the Community Health Concerns section are evaluated below.
(1) What are the health effects of nitrates and other contaminants found in private wells, especially for children, elderly, and chronically ill?
The health effects of the nitrates found in residential wells north of the landfill are described in the Toxicological Evaluation section. This information was also explained to the participants in the community survey from which the community concerns were obtained.2 All the residents interviewed were aware that nitrate contamination is a county-wide problem and probably not site-related.
Other contaminants were found in two residential wells. (See the Environmental Contamination and Other Hazards section.) The concentrations of those contaminants, which are organic compounds, were below levels of health concern. The household using this well, along with the other households in the "no well" groundwater management zone, will be offered connections to a public water supply.5
(2) Do the safe levels identified in sampling results protect sensitive individuals?
Yes, they do. The safe levels used in the sampling results are numbers established by EPA. EPA uses a "margin of safety" method of setting non-carcinogenic safe levels. In this method, the identified safe dose is adjusted by a factor of 10 to 10,000 to account for sensitive individuals, for extrapolating from animal data to humans, where appropriate, and for quality of animal and/or human data.
The nitrate safe level of 10 ppm is not adjusted by any safety factors because it is based on actual exposures of small infants (the most sensitive individuals). An example of a substance where adjustments are made is chloroform, where the safety factor is 1,000. Adjustments are to account for sensitive individuals, extrapolation of animal data to humans, and lack of a observed no effects level.
(3) Could the migraine headaches being experienced by some area residents be site-related?
It is unlikely that these migraine headaches are site-related. As described in the Environmental Contamination and Other Hazards section, there is little indication from the limited sampling done that exposures to site contaminants are occurring. Samples have been taken of the wells serving the households of the residents raising this concern.
(4) Could there be contaminants in the spray from the nearby irrigation sprinklers and could the use of those sprinklers influence the groundwater flow so that residential wells become contaminated?
Available environmental data indicate that the contaminant plume does not extend out to the wells supplying the irrigation sprinklers. However, it is possible that the use of the irrigation wells could influence the flow and direction of groundwater and result in contamination of some residential wells. The work plan for the remedial investigation of the Sussex County Landfill No. 5 includes an evaluation of this problem.
(5) Is the latex polymer that Dupont reportedly put in the landfill potentially hazardous?
ATSDR was unable to identify specific information on what was placed in the landfill. Without knowing exactly what was disposed of at the site, it is not possible to determine whether it is a health hazard. However, off-site movement of any site materials are unlikely if the site is properly covered to prevent air-borne movement and if sampling of the off-site monitoring wells continues.
Based on information reviewed, the ATSDR has concluded that the Sussex County Landfill No. 5 NPL site is an indeterminate public health hazard. This conclusion is based on a lack of the data required to evaluate the potential for and/or the amount of off-site contamination of air, soil, surface water, sediment, and the food chain.
Additional data are needed to determine: the extent of migration of the ground water contaminant plume; the extent of off-site soil contamination; the extent of off-site surface water, sediment, and air contamination; and the potential for food chain contamination. Data are also needed to evaluate the potential health threats posed by the asbestos disposed of at the site.
Ingestion of nitrite/nitrate contaminated water from 16 residential wells north of the site with levels above 10 mg/l would be a health hazard for infants under 1 year old and adults with less acidic stomachs than normal. The Sussex County Landfill No. 5 does not appear to be a source of the nitrate/nitrite contamination.
The Sussex County Landfill No. 5, Laurel, Sussex County, Delaware site has been evaluated for appropriate follow-up with respect to health effects studies by the ATSDR Health Activities Recommendation Panel (HARP). This site is not being considered for follow-up health activities at this time because no exposure to site-related contaminants was identified. ATSDR will reevaluate this site for any indicated follow-up, if data become available suggesting that exposure of humans to site-related contaminants at levels of health concern did or is occurring.
The following public health actions have been committed to by Sussex County in the final work plan for the remedial investigation of Sussex County Landfill No. 5.4
1) An evaluation of the potential for movement of contaminants off-site will be done by placing new off-site monitoring wells to the east, west, and south of the site. These wells along with the existing monitoring wells will be used to better quantify groundwater direction and flow.
2) All the on- and off-site monitoring, two irrigation, and 6 residential wells (1, 2, 9, 10, 13, and 15 on Figure 3) will be sampled for target compounds list (TCL) and target analyte list (TAL) parameters and asbestos. Both filtered and unfiltered samples will be analyzed.
3) The impact of irrigation wells on groundwater flow and direction will be evaluated by monitoring the water levels in all the monitoring wells as the irrigation wells are used.
4) The potential for movement of asbestos off-site will be evaluated by conducting on-site air monitoring for asbestos and, if any is found in the air, testing will be conducted in off-site soil for asbestos.
5) An evaluation of the potential for migration of contaminants off-site through the surface water pathway will be done by sampling on-site soil and surface water for TCL/TAL parameters and asbestos. If the results of this testing indicate that migration may be occurring, then the sediment and surface water from off-site drainageways will be tested.
Environmental and Health Effects Assessors:
Mike Allred, Ph.D.
Environmental Health Scientist
Division of Health Assessment and Consultation
John R. Crellin, Ph.D
Environmental Health Scientist
Division of Health Assessment and Health Consultation
Oak Ridge Associated Universities Summer Intern:
Ahmed E. Gomaa, M.D.,
M.S.P.H.
Tulane University School
of Public Health and Tropical Medicine
ATSDR REGIONAL REPRESENTATIVE
Regional Representative:
Charles J. Walters
Senior Public Health Advisor
ATSDR Region III
APPENDIX ONE: TABLES AND FIGURES
TABLE 1 - ORGANIC CONTAMINANTS IN MONITORING WELLS NORTH OF SUSSEX COUNTY LANDFILL NO. 51
| CHEMICAL | Range in ug/l | Found in Wells # | Comparison Value-ug/l | Source2 |
| benzene | nd - 8.0 | 1 | 5.0 | MCL |
| chlorobenzene | nd - 3.0 | 1 | 100 | DWHA |
| chloroethane | nd - 20.0 | 1 | no data | |
| chloroform | nd - 3.2 | 12, 13 | 5.7 | CREG |
| 1,4-dichlorobenzene | nd - 19.0 | 1 | 1.5 | CREG |
| 1,1-dichloroethane | nd - 2.2 | 1, 7 | 0.4 | CREG |
| trans-1,2-DCE3 | nd - 2.0 | 1 | 200 | EMEG |
| 1,2-dichloropropane | nd - 5.0 | 1 | 0.5 | CREG |
| ethylbenzene | nd - 25.0 | 1 | 100 | EMEG |
| tetrachloroethene | nd - 1.2 | 12 | 5 | PMCL |
| toluene | nd - 5.0 | 1, 10 | 3,000 | EMEG |
| total xylenes | nd - 97.0 | 1 | 20,000 | EMEG |
TABLE 2 - ORGANIC CONTAMINANTS IN RESIDENTIAL WELL 2 NEAR
SUSSEX COUNTY LANDFILL NO. 51
| CHEMICAL | Range in ug/l | Times Found | Comparison Value-ug/l | Source2 |
| benzene | 1.1 - 1.5 | 3/3 | 5.0 | MCL |
| 1,1-dichloroethane | nd - 2.6 | 1/3 | 0.4 | CREG |
| trans-1,2-DCE3 | 2.2 - 3.6 | 3/3 | 200 | EMEG |
| 1,2-dichloropropane | 1.0 - 1.4 | 2/3 | 0.5 | CREG |
| trichloroethene | nd - 2.4 | 1/3 | 5.0 | MCL |
Explanation of Tables 1 and 2
1 The source of the data in these tables is RI/FS Work Plan Sussex County Landfill No. 5, Laurel, Delaware; Roy F. Weston, West Chester, PA. August 30, 1991.
2 See the introductory paragraphs of the Environmental Contamination and Other Hazards section for an explanation of these abbreviations.
3 DCE is the abbreviation for dichloroethene.
TABLE 3. Maximum Contaminant Concentrations Present In Off-Site
Sediments of Culver Ditch (ug/kg)
|
Location
|
||
|
|
||
| Organic Contaminants | Upstream | Downstream |
| 4-methyl-2-pentanone | ND | 2.9 |
| toluene | 10 | 800 |
| toxaphene | 545.7 | ND |
| Inorganic Contaminants | ||
| arsenic | 3 Q | 6.5 Q |
| chromium | 6.9 | 12 |
| cyanide | ND | 1.6 |
| lead | 59 | 105 |
| mercury | ND | 0.12 Q |
|
|
||
F - Quantitative approximation based on quality assurance review
J - Approximate value detected below quantification limit
N - Evidence for presence of material is presumptive
P - Results of questionable qualitative significance based on quality assurance
review of data
Q - Compound present; value is below required reporting limit
ND - Not detected
SOURCE - NUS Corporation. Site Inspection of the Sussex County Landfill No. 5. TDD No. F3-8410-13. 1986. Samples collected in 1984
Figure 3. Residential, Monitor and Irrigation Well Locations
Figure 4. Groundwater Elevation Contours
