PUBLIC HEALTH ASSESSMENT
WOODLAWN COMPANY LANDFILL
WOODLAWN, CECIL COUNTY, MARYLAND
The Woodlawn Landfill site is situated at the intersection of Firetower and Waibel Roads innorthwestern Cecil County, about 2.5 miles northeast of the town of Port Deposit. The site currentlyoperates as a transfer station. During the late 1950's and early 1960's, the site was quarried for sandand gravel. It was purchased in 1965 by Cecil county and operated as a landfill (receiving bothmunicipal and industrial waste) until 1979, when it was closed under State order. Polyvinylchloride (PVC) sludge was disposed in two areas in the northeast corner of the site from 1978 to1981. Before 1978, PVC sludge was disposed wherever active landfilling operations were takingplace. Groundwater from monitoring wells that are located off site or just within the site boundarieshave elevated levels of some volatile organic chemical contaminants, including benzene, methylenechloride and vinyl chloride. Metals that were found at elevated concentrations in some of themonitoring well samples include cadmium, magnesium, manganese, mercury and sodium. A totalof 18 residential wells are within a 1/2 mile radius of the site. It is estimated that those wells supplydrinking water to about 50 to 60 people. Local residents have expressed concern regarding potentialhealth effects that could result from drinking contaminated water and about potential exposure tocontaminants in the air. Area residents have also expressed concerns that domestic animals may be harmed by exposure to site-related contaminants.
The exposure pathway of primary concern is ingestion and inhalation of contaminants ingroundwater. Vinyl chloride has been discovered at a low concentration in one residential well. Inthe spring of 1991, a treatment system was installed to decrease levels of vinyl chloride in waterused by the people. Groundwater modeling based on current conditions predicts that contaminantswill migrate to other residential wells in the future, if remedial action is not taken. Adverse healtheffects would not be expected to result from exposure to the low level of vinyl chloride that has beenfound in one residential well. Other exposure pathways of potential concern include incidentalingestion of, dermal contact with, and inhalation of contaminants by site trespassers. Based on theenvironmental sampling that has been conducted on the site, it appears unlikely that trespasserswould currently be exposed to hazardous levels of contaminants. It appears that the environmentalsampling that has been conducted both on and off of the site is sufficient to adequately characterizethe extent of contamination. It is concluded that the site poses a public health hazard because of thepotential for future exposure of local residents to groundwater contaminants.
Recommendations to protect public health include the following:
1) Establish a regular groundwater monitoring program for residential wells near the landfill;
2) Further restrict access to the site, especially during future remediation activities; and,
3) Conduct monitoring for airborne contaminants and employ dust suppression techniques during future remediation activities that may release volatile contaminants or generate dust.
To determine if public health actions are needed, ATSDR's Health Activities RecommendationPanel (HARP) has evaluated the data and information developed in the Woodlawn Landfill PublicHealth Assessment. Because there are no indications that people have been exposed to contaminantsat levels that may cause illness or disease, HARP determined that no follow-up health activities areindicated at this time. If new information becomes available indicating exposure at levels ofconcern, ATSDR will evaluate that information to determine what actions, if any, are necessary.
To further ensure that public health issues are addressed, a plan of actions has been developed. Theplan includes the following commitments by the Maryland Department of the Environment (MDE):
- MDE will make additional recommendations as needed to reduce and/or prevent exposures associated with any future remediation activities that might affect public health.
- When appropriate, MDE will communicate with local residents to provide information and assistance in understanding their potential for exposure to hazardous substances.
- MDE will contact EPA to ensure that all environmental recommendations are considered for implementation.
The former Woodlawn Landfill (WL) occupies a site of approximately 37 acres at the intersection ofFiretower and Waibel Roads in northwestern Cecil County, about 2.5 miles northeast of the town ofPort Deposit, Maryland. The site is owned and was operated by Cecil County. Figure 1 shows thesite and its immediate vicinity. An unnamed creek flows to the northwest through the southernportion of site property.
The property was operated as a sand and gravel quarry from the late 1950's to the early 1960's. In1965 the property was purchased by Cecil County and used as a county landfill. The landfillreceived both municipal and industrial wastes until 1979, when it was closed under state order. Disposal of PVC sludge in designated disposal cells continued until 1981. Waste disposal recordsdo not exist for the landfill, except for the on-site disposal of 1,272 tons of polyvinyl chloride sludgeby the Firestone Tire and Rubber Company during 1979 and 1980. The sludge was disposed in twoseparate areas in the northeast corner of the site (see Cells A, B, and C in Figure 1). Cecil Countycontinues to operate a transfer station adjacent to the site. The transfer station is used to unloadrefuse from residents and commercial vehicles, compact this refuse and reload it onto countyvehicles. Cecil County also operates a recycling center at the transfer station.
A Preliminary Assessment (PA) of the landfill was conducted by the Maryland Solid WasteManagement Administration in June 1982. Groundwater monitoring has been conducted at thelandfill by the State since 1983, and both the State and Cecil County have periodically monitoredthe water from nearby residential wells. Vinyl chloride was detected in a private well, and atreatment system was installed in Spring 1991 to decrease levels to which well users may beexposed. A development restriction area was established near the landfill by the State of Marylandin 1987. The restriction area was revised in 1989 and again in 1991. A zone surrounding thelandfill was established in which any new water supplies are prohibited. Another zone exists to thenorth of the site in which new water supplies are allowed on existing lots and an outer circle hasbeen established around the site, within which the development of new subdivisions is prohibited.
Woodlawn Landfill was placed on the National Priorities List (NPL) in July 1987. A preliminaryhealth assessment of the site was completed by the Agency for Toxic Substances and DiseaseRegistry (ATSDR) in May 1988 (1). In June 1989 a Remedial Investigation / Feasibility Study(RI/FS) was initiated by International Technology (IT) Corporation, a contractor hired byBridgestone/Firestone, Inc. (formerly the Firestone Tire and Rubber Company) and Cecil County. The RI/FS is in part designed to determine the movement of groundwater within the landfill and tocharacterize the major site contaminants and the extent to which those contaminants have migratedoff the site. The RI/FS is required by a Consent Order that was entered into on December 28, 1988,among Bridgestone / Firestone, Inc., Cecil County, MD and the U.S. Environmental ProtectionAgency (EPA).
In cooperation with ATSDR, Maryland Department of the Environment (MDE) will evaluate thepublic health significance of this site. MDE will evaluate the possibility of adverse health effectsassociated with site exposures and will recommend actions to reduce or prevent such exposures.
The site was visited on August 6, 1991, by Peter Ashley, a health assessor employed by MDE. Mr.Ashley was accompanied by an employee of the Cecil County Health Department. The following observations were made:
- The site is generally heavily vegetated with the exception of a cleared area to thewest of the transfer station; most of the cleared area is grass-covered.
- The site is not fenced and is easily accessed from a dirt road that parallels thenorthern boundary of the landfill (note: during an October 1992 site visit, MDErepresentatives observed that the entrance to this road has been blocked with a metalchain).
- The unnamed creek that flows through the southern portion of the site is too small to be used for recreational purposes such as fishing or wading. The banks of the creekare also heavily vegetated where it passes through the site, making access difficult.
The cleared area to the west of the transfer station was being used to store drums of monitoring wellwater. IT Corporation employees were encountered on the site at the time of the visit. One of the ITworkers noted that in the past he had seen dirt bike and all-terrain vehicle (ATV) tracks on the site. Another IT employee had seen signs of deer hunting (wooden hunting platforms) in the wooded areawest of the site. The landfill boundary is not obvious in this area and it may be the case that somehunting has occurred on the site property.
An area was observed between the dirt road and the northern boundary of the site (near monitoringwells ITB-1 and ITS-1; see Figure 1) that contained remnants of 2 previous campfires as well asdiscarded cans and bottles. The site is easily accessed from this point and the boundary is notposted. Large signs warning against site entry were observed along Waibel Road, just south of thejunction with Firetower Road.
Small residential developments and farms were observed in the area surrounding the landfill. Thefarm land appeared to be primarily used for grazing cattle and growing corn and hay. No significantchanges were seen during the October 1992 visit.
Based on the 1990 census, Cecil county has a total population of 71,347. About 95% of thispopulation is white; 4% of the remaining population is black, and the rest (1%) are of other racialorigins. The average population density of Cecil County is 205 persons per square mile. Thepopulation density of the census tract in which the landfill is located is 235 persons per square mile. Based on this population density, the estimated population within a one mile radius of the site isabout 700 people. The 1990 population of Cecil County was 18% greater than the population in1980.
The population living within a 1/2 mile radius of the landfill is estimated at 56 people. This is basedon the number of residential wells found within this distance from the site and the observation duringthe site visit that single family residences generally had their own wells. In making this estimate it isalso assumed that there is an average of 2.8 people per residence (1990 census data).
The land adjacent to the Woodlawn landfill is zoned primarily for agricultural and low densityresidential development. Agricultural zoning allows for single family dwellings to be built with adensity of one unit per three acres. Low density residential development allows for one housing unitper acre (personal communication, Cecil County Planning Office). There is also some land to thesouth of the landfill that is zoned for mobile home housing. There are 2 houses located immediatelyadjacent to the site; one is separated from the southern site boundary by Waibel road, and the otheris on Firetower road, directly across from the transfer station.
The former Bainbridge Naval Training center is about 1.5 miles south of the site. The center wasoperated by the Navy until the mid-1970's. After that time it was operated by the U.S. Dept. ofLabor, and was called the Chesapeake Job Corps Center. The center is currently inactive.
Natural Resource Use
Residents living near Woodlawn Landfill (in all directions from the landfill) use groundwater fromprivate wells as their household water supply. Residential wells are generally drilled into a fracturedbedrock aquifer (an aquifer is a permeable body of rock or soil and the groundwater that it contains). There are at least 20 residential wells located within a 1/2 mile radius of the landfill. Vinyl chloridewas detected at low levels in one well, and a treatment system was installed to remove the vinylchloride.
The nearest municipal water supply to the site is found in the town of Port Deposit, about 2.5 milessouthwest of the site. This town uses surface water from the adjacent Susquehanna river. Thiswater supply also serves the nearby Chesapeake Job Corps Center. There are also 2 mobile homeparks southeast of the site that use wells to supply potable water to residents. The Oaklane mobilehome park is located off of Doctor Jack Road, about 3/4 mile southeast of the site, and the MapleHill park is about 1.5 miles southeast of the site, off of Tome Memorial Highway.
The most commonly grown crops in the area are corn and soybeans. There is also some dairyfarming in the site vicinity.
As noted previously, the wooded area west of the landfill is used for hunting deer.
Available health data bases can sometimes be used to determine whether or not certain health effectsoccur more frequently in Cecil County than in the State of Maryland as a whole. This sectiondescribes these data bases; their evaluation occurs in the Public Health Implications section.
The Maryland Department of Health and Mental Hygiene (DHMH) keeps a registry of birth defectsfor the state of Maryland. The registry includes incidence data (the number of new cases that areidentified over a given time period) for 12 sentinel birth defects that hospitals are required to reportto the state. The birth defects data are available at the county level. Cancer mortality data are alsoavailable at the county level for the time period 1983 to 1987. These data were reviewed for CecilCounty, and are further evaluated in the Public Health Implications section.
Vital statistics (births and deaths) reports are available for Maryland counties from the early 1960's through 1987.
Environmental health officials with Cecil County, the State of Maryland, and EPA were questionedregarding their knowledge of community health concerns related to the Woodlawn Landfill. It wasnoted that some residents have expressed concern over potential health effects from exposure tocontaminants in groundwater (2). Those concerns have been expressed at public meetings that havebeen held to keep the public informed on the site. The most recent public meeting was held onDecember 12, 1991, in Perryville, Maryland, and was attended by a member of the MDE healthassessment team. Some local residents also submitted concerns in writing to MDE during thecomment period on the draft Woodlawn Landfill Public Health Assessment (December 14, 1992, toJanuary 17, 1993).
Two residents who live directly east of the site expressed concern (March 1992) over the source andpossible health effects of strong ammonia-like odors that they have detected in the air. One residentnoted that he has detected this odor in the air on several occasions during early evening hours. In arecent incident (March 11, 1992) a woman became faint after exposure to strong odors andemergency personnel were called to the scene. In a subsequent conversation the woman noted thatshe had been working indoors with strong cleaning solutions and she believed that her symptomswere likely due to that exposure (personal communication with local residents).
Concern has also been expressed by the community regarding possible effects of landfillcontaminants on domestic animals. That concern was raised by area residents who attended a publicmeeting on the landfill that was held in August 1990. Other concerns that were raised at the August1990 and December 1991 meetings concerned the development restriction area that has beenestablished near the site landfill.
ATSDR public health assessments focus on possible public health impacts of hazardous waste sites. Possible health risks to wild or domestic animals will not be addressed in detail. However, chemicalcontaminants may have similar effects on humans and some types of domestic or wild animals. Thispublic health assessment will not discuss the development restriction area or other concerns that do not relate to public health.
The tables in this section list the contaminants of concern in various media at the WoodlawnLandfill. The listing of these contaminants does not necessarily indicate that a health threat exists. This public health assessment will evaluate these contaminants in subsequent sections and willindicate whether exposure to them has public health significance. Selection of these contaminantswere based on the following factors:
- Concentrations of contaminants on and off the site.
- The quality of the data.
- Comparison of site-related concentrations with background concentrations, ifavailable.
- Comparison of site-related concentrations with health comparison values.
Comparison values are derived from health-based data. For example, the groundwater comparisonvalues are concentrations of substances that, when present in drinking water, would not be expectedto result in adverse health effects following chronic (i.e., lifetime) exposure or short-term (acute)exposure. Some of the comparison values (i.e., Maximum Contaminant Levels (MCL) andProposed Maximum Contaminant Levels (PMCLs) also take into account the cost and technologicalfeasibility associated with achieving those levels in drinking water. Comparison values have beencalculated by ATSDR for chemicals for which ATSDR has developed Minimal Risk Levels(MRLs). Where ATSDR values are not available, drinking water standards or guidelines calculatedfrom health data developed by EPA have been used.
To identify facilities that could possibly contribute to the chemical contamination near WoodlawnLandfill, MDE searched the 1987, 1988 and 1989 Toxic Chemicals Release Inventory (TRI). TheTRI data base was developed by EPA from the chemical release (air, water, soil) informationprovided by certain industries. The database was searched by zip code area and did not list anyfacilities in the site area that are releasing toxic chemicals.
The data presented in this subsection are the result of on-site sampling that was conducted by ITCorporation in February and March of 1991. IT Corporation is under contract to perform the RI/FSfor Woodlawn Landfill.
1. Seeps and Leachate Soils
Table 1 lists the range of the concentrations of contaminants that were measured in on-site seepageand seepage soils (3). Seeps are areas where water (and dissolved or suspended contaminants) aredraining from the landfill through the overlying soil. Seepage water and stained seepage soils weresampled from four areas of the site (south central, southeastern, and the northwestern part of the site,and in a settling basin in the south-central area of the landfill). Seepage soils were sampled from thetop six inches of stained soil from each seepage area.
Four soil and water samples may not adequately characterize the existing contamination in seepsand leachate soils on the 37-acre site; however, it does provide an indication of the types ofcontaminants that are present in those media. The substances that were identified are solvents(volatile), other organic compounds (semivolatiles) and metals. Those contaminants are commonlyfound at sites such as Woodlawn Landfill that have received mixed industrial and municipal wastes. Most of the volatile compounds that were detected in the samples (e.g., toluene, xylenes) arecommon industrial solvents. The organic chemical (volatiles or semivolatiles) that was found in thehighest concentration was bis-(2-ethylhexyl) phthalate (BEHP).
2. Borings in Waste
A total of 14 borings were made in various parts of the landfill using hollow-stem augers with anapproximate 4 inch inside diameter (3). The borings were located on the basis of the greatestlikelihood of contacting representative waste materials. Borings were collected and analyzed to helpbetter characterize the buried waste and subsurface contamination at the landfill. The borings wereextended to various depths and were terminated when the augers reached natural soils beneath thewaste. Samples from three different zones were analyzed for each boring: the upper 6 inches of soil,from within the waste, and in natural soils beneath the waste. In addition, if present, one sampleeach of sludges, oils, and powders were analyzed.
Table 2 lists the contaminants that were found in the top 6 inches of soils. Only those substances arelisted because of the potential for human exposure through direct contact to the surface soils. (Note: Surface soils are considered to be the top 3 inches of soil; however, no samples were taken of onlythe top 3 inches. The top 6 inches of soil may over or under estimate the concentrations ofcontaminants available for human contact, but the concentrations do provide estimates.) Thesamples were mixed, so it is not possible to distinguish substances found in surface soil ( 3 inchesdeep) from those in subsurface soil (> 3 inches deep). The concentrations of contaminants that werefound in the top layer of soil are generally low. The highest contaminant concentration that wasfound in the top 6 inches of soil was 15,000 parts per billion (ppb) for the plasticizing agent BEHP.
Only one of the deeper borings located polyvinyl chloride (PVC) sludge. This sludge hadconcentrations of vinyl chloride of up to 8,300 ppb (the significance of vinyl chloride will bediscussed in subsequent sections). The polyvinyl chloride sludge was disposed in two areas in thenortheast corner of the site (see areas marked as cells A, B, and C in Figure 1). Other volatileorganic compounds that were found in the borings included chloroethanes, chlorobenzene, toluene,acetone, 2-butanone, and xylenes. BEHP was found in all borings in concentrations of up to240,000 ppb.
The metals that were found in the highest concentrations in the borings were aluminum and iron. The heavy metals lead and mercury were found in many of the samples from waste borings.
Table 3 shows the range of contaminant concentrations that were measured in groundwater samplesfrom 29 on-site monitoring wells (4). Perched water (shallow groundwater underlaid by a layer ofclay that obstructs its downward movement) is found in two areas of the site. Groundwater on andnear the site is also found in a saturated soil aquifer that consists of permeable soils above bedrock. The deepest aquifer on the site is the bedrock aquifer and consists of groundwater in fracturedbedrock. Most of the residential wells near the site extend into the bedrock aquifer. The generaldirection of groundwater movement in the site area is southwest, in the direction of the Susquehannariver; however, because the landfill is situated on a hill, groundwater also flows in several directionstowards small streams north, west and south of the site.
Three rounds of groundwater sampling were conducted during the remedial investigation. Samplingoccurred in March 1990 (Round 1), November 1990 (Round 2) and February to April 1991 (Round3). Round 1 and 2 samples were analyzed for volatile and semivolatile organic compounds andinorganic substances (except selenium and antimony). Round 3 samples were analyzed for vinylchloride and semivolatile organic compounds. Table 3 includes comparison values for the listed substances in drinking water.
Common volatile organic compounds (VOC's) that were detected in the groundwater includeacetone, 2-butanone, benzene, ethylbenzene, toluene and xylenes. Vinyl chloride (also a volatileorganic compound) was present in several on-site monitoring wells, with the highest concentration(520 ppb) measured in a monitoring well (F-6) that was installed in saturated soil, south of thelargest sludge disposal area. Vinyl chloride was found at a concentration of 31 ppb in a bedrockmonitoring well (ITB-1) placed along the northern boundary of the site and at a concentration of 13ppb in an on-site saturated soil monitoring well (B-6) near the southern site boundary. Lowconcentrations of the pesticide alpha-BHC (lindane) were found in two monitoring wells. Metalsthat were most commonly found in groundwater at what appeared to be elevated concentrationsinclude iron, magnesium, manganese, and sodium. Contaminants that were detected inconcentrations that exceed the available comparison values include benzene, cadmium, manganeseand vinyl chloride. Vinyl chloride exceeded the comparison value by the largest margin.
EPA requested that Cecil County conduct an investigation of the septic system that serves the on-sitetransfer station. This study was conducted by Environmental Resources Management (ERM), Inc.(5). Site investigators observed that the station had an underground septic tank and leach field thatreceived both sewage and fluids that resulted from the compaction of solid waste. The investigationwas designed to ascertain the extent to which the compaction fluids (which would be expected tocontain common solvents, pesticides, etc.) were contaminating soils and groundwater. A monitoringwell was placed near the leach field as part of the investigation; it was sampled in February 1991. The contaminants that were detected in this monitoring well were similar to those detected in theseptic tank. The VOCs 1,2-dichloroethane and trichloroethylene were found in the monitoring wellsample at a concentration of 410 ppb and 60 ppb, respectively (compared to MCLs for both of 5ppb). Some of the contaminants that were found in this well were not found in any of the other on-site monitoring wells. Low levels of contaminants were discovered in soil samples collected atvarious depths (surface and subsurface) from the original drain field.
In the transfer station study report it is concluded that the station was not a significant source ofgroundwater contamination, based primarily on the fact that soils were not found to becontaminated. State officials would not accept this conclusion because they believed it to be basedon inadequate sampling data (personal communication with John Fairbank, MDE site manager). Additional soil sampling and analysis was more recently performed, and the results suggested thatthe soils were not a significant source of contamination. The county installed a new septic systemdrain field at the transfer station in May 1990, prior to the initiation of the drainfield study. Compaction fluids are now collected in a separate tank that is periodically pumped out.
Off-site sampling was conducted on surface water, groundwater and sediment (3). Groundwaterwas sampled from the private wells of residents living in the site vicinity and sediment and surfacewaters were sampled from the unnamed creek that flows through the southern portion of the site.
1. Surface Water and Sediment
Surface water and sediments were sampled on two separate occasions from the unnamed creek thatflows through the southern portion of the site. Samples were first collected from two different sitesduring February - March 1990 and additional sampling of six different areas was conducted inFebruary 1991. The February 1991 sampling included a drainage (referred to as a swale) that flowsinto the stream from the southern portion of the site.
During the 1990 sampling, samples were collected from areas that are immediately downstream andupstream from where the southern boundary of the site intersects the stream. A number ofcompounds were identified in the downstream but not the upstream sediment. These compoundsinclude benzoic acid, pentachlorophenol, and five chemicals within the class known as polyaromatichydrocarbons (PAHs). The PAHs are commonly occurring environmental contaminants that can beformed when organic substances are burned. Open burning was conducted on-site during the1970's. A number of metals were also found at higher concentrations in the downstream sediments;these include cobalt, iron, magnesium, manganese, nickel and vanadium. It is not possible to drawany conclusions based on only two samples; however, these results do suggest that the downstreamsediment may contain low concentrations of contaminants that have migrated from the site. Norationale was provided for the selection of the two areas that were sampled in February 1990.
The 1991 sampling showed the presence of one organic compound (pyrene) at low concentrations inone downstream water sample but not in any of the upstream samples. Metals that appeared to beslightly elevated in downstream as opposed to upstream water samples included calcium,magnesium and manganese.
The organic chemical (plasticizing agent) BEHP was identified in both upstream and downstreamsediment samples that were collected in 1991. A number of metals were found at higherconcentrations in the sediments from the swale in the southern region of the landfill as compared tosediments that were sampled from both upstream and downstream areas of the stream. These metalsinclude aluminum, barium, calcium, copper, iron, magnesium, potassium and zinc.
A biological survey of the unnamed creek was conducted in August 1991 by field biologists from ITCorporation (letter from G.B. Markert, Bridgestone-Firestone, Inc. to D. Rossi, U.S.EPA; February,6, 1992). This type of survey can be used to identify negative effects of pollution on a surface waterbody such as the creek. Certain types of aquatic insects are sensitive to pollutants, whereas othertypes are more tolerant. In this study, dip net samples of aquatic insects were taken at 2 samplingstations; one upstream and one downstream from the site. The insects from each station were thenexamined to see if there was any evidence of a negative impact from site contaminants on thedownstream segment of the stream. Although there were fewer insects collected from thedownstream site, the type and diversity (the total number of different species) of insects recovereddid not indicate that there was a negative impact from the site.
Wells of 13 private residences located near the site were sampled and analyzed during November1990 (see Figure 2) (4). Vinyl chloride (VC) was identified at a low concentration (0.18 parts perbillion) in the well of one residence (P309) located approximately 1,000 feet northeast of the siteboundary. An on-site treatment system has been installed at this residence, and the well water isbeing tested at regular intervals to ensure that the system is operating correctly. One residential well(P207), which is located near the entrance to the transfer station, was not sampled in November1990. The well at this residence was sampled in February 1992 and the water was tested for a widerange of potential chemical contaminants. Only chloroform was detected at a low concentration (6ppb) in this sample; however, it is unlikely that this is due to site contamination. Chloroform wasnot found in groundwater from on-site monitoring wells and is a common laboratory contaminant. This well will be resampled to see if chloroform is again identified (personal communication withCharles Smyser, Cecil County Health Department).
VC was not identified in the water from two residential wells (P487 and P501) located immediatelyto the south of the residential well in which the contaminant was found (i.e., between the well andthe landfill). The lack of detectable VC in these wells might be due to the fact that they areconsiderably deeper than the well in which it was found. It has been postulated that followingpumping, as the deeper wells are refilled with water following its depletion from use, water flowsdown the well wall, allowing any VC to volatilize from the water (personal communication with J.Fairbank of the MDE). VC was identified, however, in a new bedrock monitoring well (ITB-6) thatwas installed a short distance southwest of the residential well in which it was identified. This wellis about 600 feet north of the site boundary. There were no other indications that any site-relatedcontaminants had migrated through the groundwater from the landfill and into any of the residentialwells that were sampled.
A number of monitoring wells (approximately 9) were placed along the northern and westernboundaries of the site, with some of these wells placed a short distance outside of the site boundaries. It is likely that contaminants detected in groundwater from wells placed on or near the site boundarywould have migrated off of the site.
Some contaminants were detected at low concentrations (parts per billion) in groundwater from themonitoring wells placed near the site boundaries. Table 4 lists the contaminants that were detectedin those wells and the range of concentrations that were found. Comparison values for thesechemicals are also listed. Contaminants that were detected in concentrations that exceed availablecomparison values include benzene, methylene chloride, manganese and vinyl chloride. Theconcentrations of toluene and lindane that were detected in the off-site wells are considerably lowerthan their respective comparison values. The chemical bis-2-ethylhexyl phthalate (BEHP) wasfound at a concentration of 21 ppb in a saturated soil monitoring well (B-5) located near thelandfill's southern boundary.
Table 4 also lists the range of concentrations of some inorganic substances (metals) that weredetected in those monitoring wells, possibly at elevated concentrations. It is difficult to determinewhether or not the metal concentrations indicate contamination by the landfill because metals occurnaturally in groundwater at varying "background" concentrations. The metals in Table 4 are listedbecause they were found at concentrations that are considerably higher than those reported for any ofthe residential wells that were tested.
EPA sampled the water from 7 residential wells located 1/3 to 1/2 mile north of the site alongFiretower and Colora Roads and Behm Lane in August 1991 (personal communication with DebraRossi, EPA site manager). The water was analyzed for volatile organic compounds using a methodthat could accurately detect contaminants down to a concentration of 5 ppb. No contaminants werefound in the sampled water. Although concentrations of vinyl chloride below the 5 ppb cutoff wouldbe of concern for long-term exposure, it is unlikely that those wells are contaminated. This is basedon their distance from the site and the fact that most of the water from wells that are closer to the sitewas not contaminated.
Small wells called peizometers were also placed outside of the site boundaries in order to study thedirection of groundwater flow. The information gained from these and other wells were used by ITCorporation to construct a computer-generated model of the extent of current groundwatercontamination by vinyl chloride. The lowest concentration of vinyl chloride that was modelled was0.15 ppb. This is the lowest concentration that can be reliably detected using current analyticalmethods. The model predicted that the vinyl chloride plume (the edge of the contaminatedgroundwater) had reached one domestic well (P506 south of the site). If no cleanup actions wereinitiated at the site, the model predicts that the vinyl chloride plume would reach more residentialwells during the next 20 year period.
The model provides a "best estimate" of the extent of groundwater contamination. It should benoted that the groundwater near the site that is used for drinking water is found in fractured(cracked) bedrock. There are no available computer programs to model this type of material. Thecomputer program that was used assumes that the groundwater is found in a different type ofmaterial. This is a source of uncertainty in the groundwater modelling. The extent to which themodel reflects actual conditions can only be determined through additional groundwater sampling.
A summary of the Quality Assurance/Quality Control (QA/QC) data analysis was included in theRI/FS (3,4). Data validation procedures followed the Quality Assurance Project Plan (QAPP) aswell as EPA guidelines for data analysis. The data for soil borings were within QC limits forvolatile organic compounds, semi-volatile compounds, and pesticides/polychlorinated biphenyls(PCBs). The results of metal analyses for some soil boring samples did not meet QC criteria andcould not be accepted into the data base. QA/QC data for surface water and sediments wereconsidered adequate for all target chemicals except metals.
The analysis of groundwater data showed that these data were within QA/QC guidelines for alltarget chemicals (all chemicals for which samples were analyzed) except metals. The metals datawere reevaluated and it was found that the metals that were outside of the QC limits were notpresent at the landfill. Based on that finding, the metals detected at the landfill were accepted intothe data base.
Some pieces of scrap metal were observed on the site during the site visit. Some of the scrap is largeenough for a child trespasser to climb on. This activity could potentially cause injury to the childbecause of sharp edges, etc.
The build-up of explosive gases is a potential problem at former landfills, such as Woodlawn, thathave received mixed solid wastes. The major problem is with the build-up of methane, a gas that isformed from the decomposition of organic materials (i.e., garbage). Although there has been no on-site monitoring specifically for explosive gases, it is unlikely that the build-up of such gases poses aproblem to nearby residences. The distance between the area of the landfill where the mixed wastesare buried and the closest residences is sufficient to allow the gases to gradually escape through theoverlying soils (which are porous) and not reach nearby homes (personal communication with J.Fairbank, MDE project manager). The potential problem of site-generated gases will be addressed during design of the final site remediation plan.
Exposure pathways are analyzed in order to determine the means by which individuals (primarilylocal residents) may be exposed to site contaminants. An exposure pathway consists of fiveelements: a source of contamination; transport through an environmental medium; a point ofexposure; a route of human exposure; and an exposed population.
Exposure pathways can be described as completed, potential, or eliminated. In a completedexposure pathway, the 5 elements exist and indicate that exposure to a contaminant has occurred inthe past or is occurring. A "potential" exposure pathway indicates that at least one of the fiveelements is missing. It is possible that the missing element exists (e.g., an exposed population) buthas not been identified. Potential pathways indicate that exposure to a contaminant could haveoccurred in the past, could be occurring, or could occur in the future.
A completed exposure pathway exists for Woodlawn Landfill-related contaminants through use ofcontaminated groundwater in a private well. As discussed in the previous section, vinyl chloridewas identified in one residential well at a concentration of 0.18 parts per billion. A treatment systemhas reduced the exposure levels. The estimated exposed population in this case is 3 people. It maybe true that vinyl chloride has reached more private wells in the vicinity of the landfill but is presentat a concentration that is below the level that can be reliably detected (0.15 parts per billion). Because the plume of vinyl chloride and other contaminants will spread out over time, it is highlylikely that this would become a completed pathway in the future for a greater number of localresidents.
Table 5 lists a number of potential exposure pathways with respect to site-related contaminants. These pathways include on-site surface soils and seeps, off-site sediment and groundwater, andambient air both on and off of the site. Any one of these pathways may have been completed in thepast or may become complete in the future. The pathways are listed as potential pathways because itis not known whether or not individuals have actually been exposed to site contaminants throughany of them.
Keeping in mind current site conditions and available environmental sampling data (Tables 1 and 2)that indicate a low level of contamination in surface media, it is unlikely that the exposure pathwayslisted in Table 5 represent significant current sources of exposure to site-related contaminants. Also,only a small number of individuals would have the opportunity to be exposed to on-sitecontaminants, this population consisting primarily of people who occasionally trespass onto the site.
Potential exposure to surface contaminants could become greater in the future. For example, thepotential for exposure to surface contaminants could increase in significance during site remediation,when more highly contaminated soils and sludges are exposed. Site workers, visitors, and nearbyon-lookers would have an increased likelihood of coming into contact with the contaminants both inthe soils and in airborne particles and gases released from the volatile compounds.
Exposure to contaminated stream sediments (in the unnamed creek) is listed as a potential exposurepathway; however, it is unlikely that this is currently a significant exposure pathway. There waslittle evidence of site-related contamination in stream sediments and the stream is not easilyaccessed, nor is it large enough to serve as a major source of recreation.
Exposure to contaminated groundwater in residential wells is listed as a potential exposure pathwaywith respect to residents whose wells are currently uncontaminated but may become contaminated inthe future. As previously discussed, other wells may become contaminated as the plume continuesto migrate.
Although there are no available sampling data for ambient air, it is unlikely that there would be anymeasurable quantities of airborne contaminants either on or off of the site. There are no areas, suchas surface lagoons, where significant quantities of volatile contaminants are directly exposed to theair and the site is heavily vegetated, which helps to minimize the creation of contaminated airbornedust. The one exception may be during remediation if subsurface soils are excavated.
|PATHWAY||MEDIA AND TRANSPORT||POINT OF EXPOSURE||ROUTE OF EXPOSURE||EXPOSED POPULATION|
|On-site surface soil||surface soil||contaminated areas on site||ingestion, skin contact||site trespassers; |
|On-site seeps||surface water||on-site seeps||ingestion, |
|site trespassers; |
|Ambient air||air||on site, |
|inhalation||site trespassers; |
|Off-site groundwater||groundwater||residences||ingestion, |
|residents in vicinity of landfill|
|Off-site sediment||contaminated surface water and sediment||off-site sediment (stream)||skin contact||recreational users of the unnamed creek|
This section discusses the health effects that can be caused by exposure to site contaminants,evaluates state and local health data bases, and addresses specific community health concerns. Toassist in the evaluation of the potential health effects of chemicals commonly found at hazardouswaste sites, ATSDR has developed a series of Toxicological Profiles. These chemical-specificprofiles provide information on health effects, environmental transport, human exposure, andregulatory status. When sufficient information is available for a chemical, ATSDR has developedMinimal Risk Levels (MRL). A MRL is an estimate of daily human exposure to a contaminantbelow which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for eachroute of exposure, such as ingestion, inhalation, and dermal absorption and for the length ofexposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic (greater than365 days).
People are often concerned about the potential for environmental contaminants to cause cancer inexposed individuals. To help put this concern into perspective, it is important to realize thatAmericans now have about a 1-in-3 chance of developing cancer during their lifetimes (6). Although the causes of all cancers are not understood, scientists agree that lifestyle factors, such asone's diet and smoking status, are important risk factors for some of the most common cancers (suchas lung and colon cancer). Exposure to low levels of environmental contaminants are likely to causeonly a very small increase in a person's risk of developing cancer.
Two of the contaminants that have been identified in on-site groundwater (benzene and vinylchloride) are considered human carcinogens because of studies that have shown an increased rate ofcertain types of cancer in workers who were exposed to these chemicals for extended periods of timein the workplace. It may be true that exposure to very low concentrations of these chemicals, suchas the levels identified in on- and off-site groundwater, would pose no cancer risk at all. However,government agencies that are concerned with protecting public health generally make theconservative (the most health protective) assumption that the risk of cancer is increased with anyexposure to such chemicals. The same conservative assumption is made for another chemical(BEHP) that has only been shown to cause cancer in animals that are exposed to relatively highconcentrations of the chemical in their diets over their lifespans.
Not all of the substances included in Tables 1 through 4 are discussed below. An emphasis has beenplaced on contaminants that are included in Table 4 (off-site monitoring wells) because of evidencethat these contaminants are being transported off of the site. Also, some contaminants that are notdiscussed have a relatively low degree of toxicity in humans (e.g., iron and sodium in Table 3). Aswas mentioned in previous sections, the only known completed exposure pathway is for vinylchloride in groundwater.
Benzene-- Benzene is a major industrial chemical that is made from coal and oil. Benzene alsooccurs naturally in many plants and animals. Benzene is known to be a human carcinogen (7). Leukemia (cancer of the tissues that form the white blood cells) has occurred in some workersexposed to benzene for periods of less than 5 and up to 30 years. Long-term exposures of humans tobenzene may also affect normal blood production. Human and animal studies also indicate thatbenzene is harmful to the immune system. Exposure of pregnant animals to benzene has resulted inadverse effects on fetuses; however, there is no clear evidence of adverse reproductive effects inhumans (7). Benzene has been identified in the water of monitoring wells on and off of the landfill,but it has not been identified in any residential wells near the site.
The highest concentrations of benzene that have been identified in both on- and off-site groundwatermonitoring wells are 75 and approximately 2 ppb, respectively. The on-site concentration isconsiderably higher than the Maximum Contaminant Level for benzene of 5 ppb. Lifetime exposureof people to this concentration in drinking water would pose an unacceptably high cancer risk (7). Benzene was not identified in any of the residential wells that were tested; therefore, no risk ofadverse cancer or non-cancer effects are expected to people in the community as a result of benzeneat the site. Should private well water become contaminated with benzene in the future, any humanexposure to the water should evaluated for possible adverse health effects at that time.
Bis(2-ethylhexyl)phthalate (BEHP)-- BEHP is a chemical that is commonly used to make plasticsmore flexible. Plastics may contain from 1 to 40% BEHP by weight. Humans are primarilyexposed to BEHP through foods that come into contact with packaging material that contains it. There are no studies on the health effects of BEHP in humans, although there have been no reportsof adverse health effects in workers who are exposed to BEHP (8). Studies in which laboratoryanimals (rats and mice) were given BEHP in food have shown that adverse effects on the liver anddeveloping fetuses occur at the lowest levels of exposure. BEHP has also produced liver cancer inrats exposed to high concentrations of the chemical in food over a two year period (8).
Low concentrations of BEHP (up to 140 ppb) were found in on- and off-site groundwater. Thisconcentration would not be expected to cause any adverse health effects in exposed individuals;however, lifetime exposure to this concentration (140 ppb) in drinking water might result in a slightincrease in an individual's cancer risk (8). The highest level of BEHP found in on-site leachate soilsis 5,800 ppb. This level of BEHP in soil does not represent a significant health hazard. Thischemical does not evaporate easily and is not easily absorbed through the skin (8).
Methylene Chloride-- Methylene chloride is a widely used industrial solvent and paint stripper. Inhumans, exposure to sufficiently high concentrations of methylene chloride in air (about 500 ppm)can cause irritation to the eyes, nose and throat (9). Exposure to these levels can also cause centralnervous system symptoms similar to those caused by alcohol intoxication. Methylene chloride hascaused cancer of the liver and lung in laboratory animals exposed by inhalation to high levels of thechemical over a lifetime. The chemical has also caused liver cancer in laboratory animals followinglong-term oral exposure. There is no evidence for an increase in cancer deaths in humansoccupationally exposed to methylene chloride (9). Methylene chloride was identified in off-sitemonitoring wells, but it was not found in residential wells near the site.
Methylene chloride was found in both on- and off-site monitoring wells at a highest concentration of38 ppb. Lifetime exposure of people to this level of methylene chloride in drinking water mightresult in a slight increase in an individual's risk of developing cancer should private wells everbecome contaminated (9). At present, no one is exposed to the contaminant; therefore, no adversehealth effects as a result of methylene chloride are expected to occur.
Vinyl chloride-- Humans occupationally exposed to high levels of vinyl chloride vapors have showndamage to the liver, central nervous system and peripheral blood circulation (10). Long-termoccupational exposures have also been associated with cancer of the liver and possibly the brain. Exposure of laboratory animals to vinyl chloride vapor has also caused liver cancer (10).
There is no information on the effects of vinyl chloride in humans following oral exposure. Oralexposure of laboratory animals to vinyl chloride has caused liver toxicity and cancer of the liver. ATSDR has developed a Minimal Risk Level (MRL) for long-term oral exposure to vinyl chlorideof 0.0013 mg/kg/day (10). This is equivalent to a concentration in drinking water of about 30 partsper billion (ppb). No non-cancer adverse health effects would be expected from long-term exposureto the low concentration of vinyl chloride that was found in one residential well (the highestconcentration observed was about 0.2 ppb). Long-term exposure to this level of vinyl chloride indrinking water might result in little to a slight increase in the individual's risk of developing cancerduring his or her lifetime (10).
Manganese-- Manganese is a naturally occurring substance found in many types of rock. People areregularly exposed to low levels of manganese in water, air, soil and food (11). A certain amount ofmanganese in the diet is believed to be necessary for good health. Manganese has caused disease inworkers exposed to high levels of manganese-containing dust in the air for a year or longer. Symptoms of the disease include mental and emotional disturbances and incoordination. It is notknown whether or not oral exposure of humans to manganese can cause the disease associated withdust exposure (11). Manganese has not been found at increased concentrations in residential wellsnear the landfill; therefore, no risk of adverse health effects are expected to people in the communityas a result of manganese at the site. However, it has been found in on-site and off-site monitoringwells at levels that are higher than the health comparison value. Should private well water becomecontaminated with manganese in the future, any human exposure to the water should evaluated forpossible adverse health effects at that time.
As noted previously, the Maryland Department of Health and Mental Hygiene has vital statistics(births and deaths) and birth defects data available for given time periods at the county level. In thediscussion that follows, the rates for Cecil County are compared to rates for the State as a whole.
MDE believes that it is very unlikely that people have been exposed to sufficient quantities ofcontaminants from the Woodlawn Landfill to result in any detectable increases in exposure-relatedillness. This notwithstanding, an evaluation of the available health outcome data is included in thissection. A number of points should be considered when these data are evaluated with respect to thepotential impact of exposure to site-related contaminants. These points include the following:
- A plausible link between exposure to a chemical and an adverse health effect requires that the chemical be capable of causing the effect of concern, and that there was sufficient exposure (resulting in enough of the chemical being absorbed into the body) to cause the effect.
- If exposure to site contaminants did cause serious adverse health effects in some exposedindividuals, it might not be possible to detect this using the available health outcome data. For example, if exposure to contaminants from the landfill resulted in 2 deaths from lungcancer (as noted, we do not consider this plausible), these "extra" cases might not cause anoticeable increase in the lung cancer death rate when they are combined with all of theother lung cancer deaths for Cecil County. This is especially true if the disease of concern (such as lung cancer) is not rare.
- A certain disease or condition (e.g., a certain type of cancer or birth defect) may occur at agreater than expected rate in Cecil county as compared to the state of Maryland as a wholedue to chance alone. Also, observed differences between State and county rates may be dueto differences in the two populations. For example, if the risk of a certain birth defectincreases with the age of the mother, and the defect is observed to be increased in the countyas compared to the State, the reason for the increase may be due to a greater proportion of older women giving birth in the county during the observed period.
It should be noted that if the public health assessment team at MDE suspected that exposure to site-related contaminants was causing disease or illness in an exposed population, MDE wouldrecommend that a more detailed study of this population be initiated. This recommendation willalso be made if a review of health outcome data that become available in the future indicates theneed for a more detailed investigation.
With the above points in mind, the following health outcome data have been reviewed for CecilCounty:
Data for the occurrence of thirteen separate birth defects (referred to as sentinel defects) areavailable for Maryland at the county level for the years 1984 to 1988. During this time period, theincidence rate for infants born with one or more of the 13 defects was 95.9 per 10,000 for Cecilcounty (34 infants out of 3,547 total births) as compared to 63.8 per 10,000 (1,920 infants out of300,882 total births) for the State of Maryland as a whole. The two types of birth defects thatoccurred at a significantly higher rate (based on statistical analysis) among Cecil County births ascompared to the state as a whole were spina bifida with or without hydrocephaly (14.1 per 10,000live births for the county as opposed to 5.3 per 10,000 live births for the state) and Down Syndrome(19.7 per 10,000 live births for the county as opposed to 7.2 per 10,000 live births for the state).
The birth defect rates for spina bifida and Down Syndrome in Cecil county are based on totals of 5and 7 cases, respectively, out of the 3,547 births that occurred in the county during the 4 yearperiod. These rates are thus based on a relatively small number of cases.
The increased rate of the 2 birth defects that was observed in Cecil County during the four yearperiod is not likely due to exposure to contaminants from the Woodlawn Landfill. The only knowncompleted exposure pathway for this site is for a very low concentration of vinyl chloride in thedrinking water supply of one residence. Local residents may also have been exposed to airbornecontaminants; however, this would likely have been an infrequent exposure to low concentrations ofvolatile chemicals, and would not be expected to cause adverse health effects. Spina bifida has beenassociated with dietary deficiencies in the mother and Down Syndrome is more prevalent when themother is older. Other possible causes of those birth defects are not clearly understood.
Age-adjusted (to 1970 U.S. population) death rates are available at the county level for the period of 1983 to 1987. Average annual cancer death rates per 100,000 population were not significantly different (based on statistical analysis) for Cecil County as compared to the State of Maryland as a whole for the most common forms of cancer (see below).
|(cancer death rates per 100,000)|
As noted previously, no conclusions can be made regarding the impact of site-related contaminants on the health of exposed individuals based on our evaluation of the available health outcome data. It can be concluded that during the period from 1983 to 1987, residents of Cecil County did not die from the cancers listed above at rates that differed significantly from the residents of the State of Maryland as a whole. It can further be concluded that 2 of 13 birth defects occurred at a significantly higher rate in the county as compared to the state as a whole during the period from 1984 to 1988.
The increased rate of those birth defects are not likely a result of environmental exposures tocontaminants from the site because people are known to have only been exposed to low levels ofvinyl chloride, which has not been associated with those birth defects. Spina bifida has beenassociated with dietary deficiencies (folic acid) of the mother and Down Syndrome is more prevalentwhen the mother is older. Other factors that may be associated with the birth defects are not clearlyunderstood.
1) The potential hazard posed by exposure to contaminated groundwater.
A low concentration of vinyl chloride (approximately 0.2 ppb) has been discovered in one residentialwell. Vinyl chloride is considered a human carcinogen as a result of observations of increased ratesof cancer (primarily of the liver) in workers who were exposed to high levels of the chemical. Thelevel of vinyl chloride that was observed in the well is one tenth of the Maximum ContaminantLevel (MCL) of 2 ppb that has been established by the U.S. EPA for public drinking water supplies. Based on conservative exposure assumptions, residents that drink and bathe for a lifetime in watercontaminated with the low concentration (i.e., about 0.2 ppb) that was discovered in the residentialwell, may result in a very slight increase of risk of developing cancer. In the residence where vinylchloride was discovered, continued exposure has been prevented by the installation of a watertreatment system.
No contaminants have been detected in other residential wells that have been tested in the sitevicinity (i.e., along Firetower, Colora and Waibel roads). Residents living near the site who areconcerned about possible contamination of their groundwater can have the water tested by makingarrangements with the Cecil County Health Department.
2) The source and possible health effects of odors detected by residents living near the site.
Two residents living on Firetower road, east of the site, have complained of encountering strong,ammonia-like odors. One resident stated that he encountered these odors during the early eveninghours on several occasions. Because the identity of the gases causing these odors is not known, it isnot possible to discuss the potential health effects associated with exposure. The odors weredescribed as strong and irritating. In one reported incident a woman became light-headed followingexposure to chemicals in air. This woman had been using cleaning products prior to this incidentand this may have caused or contributed to her symptoms.
The source of these odors is not known. Gases that are generated by landfills such as Woodlawn inthe greatest amounts include carbon dioxide, methane, nitrogen, and occasionally hydrogen sulfide(12). These gases are all odorless with the exception of hydrogen sulfide, which has a strong rotten-egg odor. Volatile organic compounds such as vinyl chloride, toluene, and benzene can also bepresent in lower concentrations.
A possible source of ammonia-like odors in the area around the site is from the spreading of manureon fields as well as its storage in manure ponds. A dairy farm that stores manure in ponds is locatedabout 1 mile north of the site. Also, ammonia-containing fertilizers are sometimes applied directlyto fields.
3) Potential effects of site-related contaminants on domestic animals.
The main surface pathway for the off-site transport of contaminants appears to be the unnamed creekthat flows through the site. The stream water and sediment samples that were analyzed showed onlyvery low levels of contamination at the time of sampling. Also, the results of biological sampling ofthe stream did not indicate that the site was adversely affecting water quality in the downstreamsection.
Based on these results, it does not appear that the stream would currently pose a health hazard to domestic animals that drink from it downstream of the landfill.