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PUBLIC HEALTH ASSESSMENT

REVERE CHEMICAL COMPANY
NOCKAMIXON, BUCKS COUNTY, PENNSYLVANIA

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The tables in this section list the contaminants of concern. This public health assessmentevaluates these contaminants in subsequent sections and determines whether exposure to themhas public health significance. PADOH selected these contaminants based upon the followingfactors: on and off-site concentrations; field and laboratory data quality and sample design;comparison of site-related concentrations with background concentrations; and comparison ofsite-related concentrations with health assessment comparison values for carcinogenic andnoncarcinogenic endpoints. Comparison values for health assessments are contaminantconcentrations in specific media that are used to select contaminants for further evaluation. These values include Environmental Media Evaluation Guides (EMEGs), Cancer RiskEvaluation Guides (CREGs), and other relevant guidelines.

In the data tables which follow under the on-site contamination and off-site contaminationsubsections, the listed contaminant does not mean that it will cause adverse health effects fromexposure. Instead, the list indicates which contaminants will be evaluated further in the publichealth assessment. When selected as a contaminant of concern in one medium, that contaminantwill be reported in all media.

The data tables include the following acronyms:

CREG = ATSDR Cancer Risk Evaluation Guide
D = The sample was diluted in order to bring the compound into calibration range.
J = The Associated Numerical Value Is An Estimated Quantity
MCL = USEPA Maximum Contaminant Level
NA= Not Available
ND = Not Detected
NT = Not Tested
PMCL = USEPA Proposed Maximum Contaminant Level
ppm = Parts Per Million
RMEG = Reference Dose Media Evaluation Guide
µg/L = Microgram per Liter

The USEPA Toxic Chemical Release Inventory data base was accessed by the PADOH throughthe National Library of Medicine's Toxicology Data Network and searched for estimated annualrelease of toxic chemicals to the environment, from industries within a 2-mile radius of theRevere Chemical site, to identify possible facilities that could contribute to air or groundwatercontamination near the site. No significant releases which would affect the air or groundwaterquality near the site were reported in the 1987, 1988 and 1989 data bases.

A. On-Site Contamination

Groundwater - Monitoring Wells

The Phase I groundwater investigation included the installation and sampling of five groundwatermonitoring wells, designated MW-1 through MW-5. The Phase IA groundwater investigationconsisted of installing and sampling one monitoring well (MW-6). Monitoring well MW-6 wasan overburden well that was decommissioned after review of the analytical results indicated theabsence of any compounds of concern (1). Six monitoring wells (MW-7 through MW-12) wereinstalled in the process area for the Phase II monitoring wells by Eichelberger Drilling Companyof Mechanicsburg, Pennsylvania, from March 25, 1991 through April 5, 1991. These wells wereinitially drilled to a minimum depth of 100 feet in accordance with the Phase II Work Plan. Thewells were then advanced in 25-foot increments until the first water-bearing zone wasencountered, at which time drilling was terminated. Appendix B provides monitoring wellinstallation and modification data.

Dames & Moore collected one round of groundwater samples from the Phase I and Phase IImonitoring wells on June 12 and 13, 1991. The presence of bentonite in MW-1 prevented thecollection of groundwater samples from this well. The groundwater samples collected wereanalyzed by the Environmental Testing and Certification (ETC) Corporation of Edison, NewJersey. This analysis included: Target Compound List (TCL), volatile organic compounds(VOCs), polychlorinated biphenyls (PCBs), Target Analyte List (TAL) metals, and hexavalentchromium. Figure 4 indicates the well locations and Table 1 indicates the concentrations ofcontaminants of concern.

Table 1. Maximum Contaminant Concentrations in On-Site Monitoring Wells (1)

CONTAMINANTMAXIMUM CONC.
µg/L
COMPARISON VALUE
Phase 1Phase 2µg/LSOURCE
Trichloroethene (TCE)1101105MCL
1,2,4-Trichlorobenzene (TCB)110419MCL
BerylliumND5.97a0.0081CREG
Chromium* (Total)26.1a90.0a100MCL
Lead29.1a113.0Da0PMCL

a Unfiltered
b Child
* In addition to total chromium, tests were conducted for hexavalent chromium in somesamples. However, the data have been considered invalid. Future groundwater samples formetals will be analyzed for hexavalent chromium by both the atomic absorption method (USEPAMethod No. 218.4) and the colorimetric method (SW 846-7197) (1).

Soil - Phase I

The objectives of the Phase I soil sampling were to: 1) determine the composition, stratificationand thickness of on-site soils and 2) evaluate the presence or absence and vertical distribution ofpotential contaminants in on-site soils. Soil samples were collected from four areas of the site: background soil samples, east spray field, south spray field and the process area. All soilsamples and background soil samples were analyzed by ETC for the following parameters (2):

  • TCL, including VOCs, pesticides, and PCBs.
  • TAL, including metals and cyanide.

Dames & Moore collected all the samples. The background samples were collected onNovember 11, 1989. Other samples were collected between October 5-20, 1989. A discussionof the sampling from the other four areas of the site follows.

    Background Samples - A total of three background soil samples (SBG1 to SBG3) were collectedfrom a depth interval of 0-1 foot with a stainless steel hand auger. These samples were collectedfrom relatively undisturbed, peripheral locations at the site, which were least likely to have beenimpacted by site operations.

    East Spray Field - Eighteen soil samples were collected at eight locations (S34 to S41) from twointervals (A and B). The total includes two replicates from interval A. Interval A samples werecollected from 0 to 1 foot below ground surface (BGS), and interval B samples were collectedfrom the 1-foot interval above bedrock, or from the deepest 1-foot interval from which arepresentative soil could be taken. This is true in all areas of soil testing.

    South Spray Field - Seventeen soil samples were collected at 8 locations (S42 to S49) from twointervals (A and B). The total includes one replicate from interval A.

    The Process Area - A total of 81 soil samples and replicates were collected at 40 locations (S1 toS33 and S50 to S56). Forty samples and 3 replicates were collected from interval A at locationsS1 to S26 and S50 to S56. For samples S27 to S33, the interval A sample was collected from 1to 2 foot BGS (except S28, which was collected from the 2 to 3 foot BGS).

    Twenty-eight samples and 4 replicate samples were collected from interval B in the process area. For samples S1 through S22, when little or no signs of potential contamination were observed inthe trenches, interval B samples were collected from the 1-foot interval above bedrock.

No interval B sample was collected from location S18, because bedrock was encountered at 1.6feet. For samples S50 through S56, the interval B sample was collected from 1 to 2 foot BGS.

For samples S50 through S56, six soil samples were collected from interval C, which was the 1-foot interval above bedrock. Bedrock was encountered at 2.4 feet at location S50; thus, theinterval B sample was collected from 1.4 to 2.4 foot BGS, and no interval C sample wascollected.

The soil samples were collected from 56 trenches excavated with an extendahoe (a backhoe withextended reach). Soil samples collected from the trenches were intentionally biased towardlocations that exhibited the most, of any, visual and textural signs of potential contamination (2). The objective of this biased sampling approach was to evaluate the need for further study in eachlocalized area of potential concern. The results of this approach were not intended to berepresentative of conditions across the whole site; however, they did provide informationnecessary for Phase II soil sampling.

Contamination to soil was most intensive in the process area. VOC contamination in the soilwas nearly confined to the process area. Acid extractable compounds (AEs) and pesticides wereso limited in Phase I sampling that they were deleted in the Phase II sampling plan. Tables 2a and 2b indicate maximum concentrations of contaminants of concern in Phase I and Figure 5 indicates the sample locations.

Table 2a. Maximum Contamination Concentration in Selected Areas in Phase I
(Interval A) Soil Sampling (2)

CONTAMINANTSAMPLE LOCATIONCOMPARISON
VALUE
Background
Samples
ppm
Process
Area
ppm
East
Spray
Field
ppm
South
Spray
Field
ppm
ppmSource
Trichloroethene (TCE)NT9,100.0NDNDNA
1,2,4-Trichlorobenzene (TCB)NT780.0JND700NA
Beryllium1.3170.03.21.2250 RMEG
Chromium (Total)30.015000.0690.058.0NA
Lead38.01500.024.024.0NA

Table 2b. Maximum Contamination Concentration in Selected Areas in Phase I
(Interval B) Soil Sampling (2)

CONTAMINANTSAMPLE LOCATIONCOMPARISON
VALUE
Process Area

ppm

East Spray Field
ppm
South
Spray
Field
ppm
ppmSource
Trichloroethene (TCE)700.0NDNDNA
1,2,4-Trichlorobenzene (TCB)1,000,000.0NDNDNA
Beryllium91.01.61.8250RMEG
Chromium (Total) 20,000.0 77.0 47.0 NA
Lead 3,600.0 17.0 6.9 NA

Soil - Phase II

The Phase II soil investigation involved the collection and laboratory analysis of soil samples formetals in the entire process area. Selected areas of the east and south spray fields, whereconcentrations of metals were detected above two times background concentration in soilsamples during Phase I, were also sampled and submitted for laboratory analysis for metals. Based on historical documentation of site operations and the results of the Phase I investigation,soils outside of the process area have not been significantly impacted by VOCs.

Dames & Moore monitored the drilling of Phase II soil borings by Walton Corporation ofNewark, Delaware between April 16 and May 16, 1991. Dames & Moore collected samples inMay 1991. Each soil sample collected during the Phase II soil investigation was submitted toETC of Edison, New Jersey for laboratory analysis. Laboratory analytical procedures requiredfor specific samples that could not be performed by ETC were subcontracted to alternatelaboratories. The Quality Assurance Project Plan (QAPP) issued by ETC for the RevereChemical Site Phase II Remedial Investigation/Feasibility Study (RI/FS) Work Plan wasapproved by USEPA before initiating the collection and analysis of laboratory samples.

The Phase II soil investigation for metals involved the collection of soil samples using 3-inch(outside diameter) stainless steel split-spoon samplers. Samples were collected at theintersections of the north and east 200-foot by 200-foot grid coordinates established for the site. Sample collection locations based on the grid coordinate system provided a non-biased samplingapproach that was designed to provide representative data for the site. Additional samples werecollected from areas identified during the Phase I investigation that contained elevated metalsconcentrations, such as former site facilities, to define the level and extent of these metals in sitesoil (1).

The Phase II soil investigation for metals included the collection of soil samples from 73locations cited on the 200-foot by 200-foot grid coordinate system, and 32 locations within theboundaries of the former site facilities, including the former process lagoons, storage lagoons,collection basins, sump pit, Process Refuse Area and waste lagoon (Figure 5). A discussion ofbackground samples, east and south spray field samples and process area samples follows:

    Background Samples - Five background soil samples were collected during Phase II. The PhaseII background sample locations are cited at least 200 feet from an area of contaminated soilidentified during Phase I. Typically, the background soil samples were collected within stands of60 to 80-year old trees that predate manufacturing activities at the Revere Chemical site, and donot show signs of vegetative stress indicative of site contamination. These areas are consideredto be representative of background conditions (1). See Figure 5.

    East Spray Field - Forty-eight soil samples, including replicate samples and matrix spikes/matrixspike duplicates (MS/MSD) sample pairs collected as a quality assurance measure, werecollected from the east spray field at 21 sampling locations, identified as ESM001 throughESM021 (Figure 5). Dames & Moore collected the samples in May 1991 and ETC analyzed thesamples for TAL metals. The samples collected included 24 interval A and 24 interval B soilsamples as previously defined. Because no visible indications of metals contamination (metalsludges, granular materials) were observed in the field, discrete samples (interval C) were notcollected from the east spray field.

    South Spray Field - Eighteen soil samples, including an MS/MSD pair collected as a qualityassurance measure, were collected from the south spray field at eight locations in May 1991. Dames & Moore collected the samples and ETC analyzed the data for metals. The samplescollected included on sample from each sampling depth interval (A and B) at each metalssampling location. Interval C samples were not collected because visible indications of metalscontamination were not evident.

    The Process Area - In May 1991, Dames & Moore collected 179 soil samples, including 80interval A samples and 82 interval B samples from 76 locations in the process area. The intervalA samples included three pairs of MS/MSD samples and one quality assurance replicate sample. The interval B samples included six pairs of MS/MSD samples and seven replicate samples. Depth-discrete soil samples were collected at eight of the Phase II metals sampling locations. These samples (interval C samples) were collected from specific subintervals within intervals Aor B that exhibited visible indications of metals contamination. ETC analyzed the samples forTAL metals.

    The Phase II soil investigation defined the degree and extent of inorganic and organicconstituents detected in the soil during the Phase I RI. Metals concentrations were generallygreater in the interval A soil than the interval B soil. The greatest metals concentrations at thesite are usually associated with the former process and storage lagoons in the process area. Onlychromium and copper (not a contaminant of concern) were present in both the east spray fieldand south spray field at significantly distinguishable concentrations with respect to backgroundsoil samples (1). Organic concentrations were found at only very low concentrations outside theprocess area.

Tables 2c and 2d indicate maximum concentrations of contaminants of concern in Phase II and Figure 5 indicates the sample locations.

Table 2c. Maximum Contamination Concentration in Selected Areas in Phase II
(Interval A) Soil Sampling (1)

CONTAMINANTSAMPLE LOCATIONCOMPARISON
VALUE
Background
Samples
ppm
Process
Area

ppm

East
Spray
Field
ppm
South
Spray
Field
ppm
ppmSource
Trichloroethene (TCE)NT22.2NDNDNA
1,2,4-Trichlorobenzene (TCB)NT749.0NDNDNA
Beryllium2.11583.21.7250RMEG
Chromium (Total)45.01,080J60.0170.0NA
Lead49.0710J76.0J51.0JNA

Table 2d. Maximum Contamination Concentration in Selected Areas in Phase II
(Interval B) Soil Sampling (1)

CONTAMINANTSAMPLE LOCATIONCOMPARISON
VALUE
Process Area

ppm

East Spray Field
ppm
South
Spray
Field
ppm
ppmSource
Trichloroethene (TCE)16.5NDNDNA
1,2,4-Trichlorobenzene (TCB)200.0JNDNDNA
Beryllium463.0J1.81.7 250RMEG
Chromium (Total)3,130.0J62.0120.0JNA
Lead2,100.0J10.013.0JNA

Metals Partitioning Study

To determine the potential for mobilization of metals in the site soils due to rainfall infiltration topotentially impact groundwater, a metals partitioning study was conducted as part of the Phase IIsoil investigation. The technical aspects of this study are beyond the scope of this public healthassessment. However, the findings indicated that the metals mobilization related to rainfallinfiltration through the overburden soil column is minimal. The results, in summary, indicatedthat soils contaminated with metals did not greatly affect the groundwater (1). Five soil sampleswere taken in April 1991 and analyzed for designated geochemical parameters by CoreLaboratories of Aurora, Colorado.

Soil Gas Survey

Dames & Moore retained Tracer Research Corporation (Tracer) to conduct a soil gas survey todelineate the extent of VOC contamination in the process area. The soil gas survey wasconducted at the site from October 15 through November 2, 1990. Soil gas data were collected atapproximately 290 locations and analyzed for the following seven compounds: trichloroethene(TCE), tetrachloroethene (PCE), 1,1,1-trichloroethane (TCA), benzene, toluene, ethylbenzeneand xylenes. The soil gas samples were analyzed by Tracer immediately after collecting eachsoil gas sample. These compounds were selected for analysis because they were among the mostfrequently detected VOCs in Phase I soil samples and are amenable to the soil gas surveytechnique, due to their relatively high volatility and low solubility. The concentrations detectedwere below levels of concern (1).

B. Off-Site Contamination

Groundwater - Residential Wells

The Bucks County Health Department collected samples from three residential wells on April 2,1985. Analyses of the samples indicated that the following constituents were present: (1) nickelwas detected in all three residential wells sampled; (2) arsenic was detected above the minimumdetection limit (MDL) in one of the three residential well samples; (3) the VOCs TCE and TCAwere detected in one residential well sample (1). However, the validity of the data isquestionable because of the lack of supporting documentation such as field sampling andlaboratory analytical procedures and protocols, and analytical results for quality assurance/qualitycontrol samples analyzed concurrently with the referenced water sample (1).

ATSDR expressed concern regarding the contaminants in these three residential wells. Basedupon these concerns, the USEPA requested that these three wells be sampled during the Phase IIRI. There was conflicting information regarding the homeowners' names and mailing addressescaused by two of the residents names being almost identical. Consequently, four wells, insteadof three, were sampled. Figure 6 indicates persons involved in the residential well survey andresidence numbers 9, 10, 26 and 42 indicate the wells sampled. Dames & Moore collected thesamples in June 1991 and the samples were analyzed by the ETC Corporation for: TCL, VOCs,TAL metals and hexavalent chromium. Nickel was not detected in any well samples. Arsenicwas found above the contract-required detection limit (CRDL) in two wells. The maximumconcentration was 32.0 µg/L in a filtered sample in well number 9 (note: an unfiltered samplewould have been preferable because that is more representative of what people actuallyconsume). 1,1,1-Trichloroethane was found below the detection limit at an estimated value of 3µg/L in well number 10. The maximum concentration for the contaminants of concern areindicated in Table 3.

Table 3. Maximum Contaminant Concentration in Selected Residential Wells (1)

CONTAMINANT
COMPARISON VALUE
µg/Lµg/LSource
Trichloroethene (TCE)2J5MCL
1,2,4-Trichlorobenzene (TCB)ND9MCL
BerylliumND0.0081CREG
Chromium (Total)ND100MCL
Lead (Filtered)25.10PMCL

Groundwater - Cotner Trailer

Dames & Moore collected a groundwater sample from the well at Cotner Trailer which isadjacent to the site to the north. This sample was collected in June 1991 and analyzed by theETC Corporation for TCL VOCs, TAL metals and hexavalent chromium. Figure 2 shows thelocation of Cotner Trailer. None of the contaminants of concern were detected in the Cotner wellwith the exception of lead which was found at 7.9 µg/L in an unfiltered sample and 3.97 µg/L ina filtered sample.

Fresh-Water Pond Investigation

A man-made pond (referred to as the fresh-water pond), approximately 150 feet long and 100feet wide, is located in the northern portion of the process area.

On October 17, 1990, one sediment sample was collected from the northwest corner of the fresh-water pond. The sample was collected by advancing a stainless-steel hand auger into thesediment to a depth of 8 inches. The sediment sample was analyzed by Environmental Testingand Certification (ETC) Corporation of Edison, New Jersey for: (1) TCL parameters, includingVOCs, AEs, B/Ns, pesticides and PCBs and (2) TAL parameters, including metals and totalcyanide. TAL metals were not detected in the sediment sample at concentrations that weredistinguishable from background soil concentrations. No B/Ns, AEs, pesticides or PCBs weredetected in the samples. No VOCs were detected that were believed to be related to metalsreclamation at the site. Methylene chloride (8 micrograms per kilogram [µg/kg]) and acetone (75µg/kg) were detected in the pond sediment sample.

On October 17, 1990, two aqueous samples (one filtered and one unfiltered) were collected fromthe northwest corner of the fresh-water pond. The samples were collected by immersing thesample bottle into the pond water at a point as close to the mid-depth of the pond as possible. The samples were analyzed by ETC Corporation. The unfiltered sample was analyzed for TCLparameters, including VOCs, AEs, B/Ns, pesticides and PCBs, or TAL parameters, includingmetals and hexavalent chromium. The filtered sample was analyzed for TAL metals (dissolved),total cyanide and hexavalent chromium.

No VOCs, AEs, B/Ns, pesticides or PCBs were detected in the aqueous samples. The unfilteredand filtered aqueous samples collected contained TAL metals. However, the concentrations ofthe TAL were below Federal Primary Drinking Water Standards (1).

The fresh-water pond was established and approved by the USEPA as a suitable source fordecontamination water for field activities.

Ecological Investigation

The Phase II ecological investigation included: a wetlands delineation; a survey for threatenedand endangered species; a study of the aquatic community in the surface water bodies at the site;a study of the terrestrial plant communities in the spray fields; and toxicity tests performed onspray field soil, stream sediment, and surface water. A summary of this comprehensive studyfollows.

The aquatic community survey indicated that there was some adverse impact to the benthiccommunity on-site, but this decreased with distance from the process. No adverse impact to thebenthic community was evident in Rapp Creek (1).

The terrestrial plant community survey revealed that there was no detectable toxic effect from thesoil in the spray fields on the plant communities.

Sediment and surface water analysis was performed. No VOCs or PCBs were detected in streamsediment samples or in stream water samples. Maximum concentrations in ppm for streamsediments indicated beryllium at 10.2, chromium at 336 and lead at 51. Beryllium and chromium(trivalent and hexavalent) were not detected in surface water samples. Lead was found at amaximum of 8.3 µg/L in one filtered sample.

C. Quality Assurance and Quality Control

Four types of quality assurance/quality control (QA/QC) samples were collected during the PhaseI RI: (1) trip blanks, (2) field (equipment rinsate) blanks, (3) replicate samples and (4) matrixspike and matrix spike duplicate samples.

The purpose of the trip blanks was to investigate the potential influence of sample bottlepreparation and sample handling procedures upon the concentrations of VOCs detected in theactual samples. The purpose of the field blanks was to investigate whether or not the samplingdevices and procedures may have introduced additional analytes into the samples. The purposeof the replicate samples was to assess the degree of homogeneity of the samples and the precisionof the sampling procedures. The purpose of the matrix spike and matrix spike duplicate sampleswas to evaluate the analytical performance of the laboratory with respect to the sample matrices.

The samples collected at the Revere Chemical site during the Phase II RI were analyzed inaccordance with the protocols and procedures established in the USEPA Contract LaboratoryProgram (CLP) Statements of Work (SOW) for Organics Analysis (1990) and InorganicsAnalysis (1990), when applicable. In addition, the Phase II RI included the analysis of specificsamples for non-CLP parameters. For these analyses, USEPA analytical methodologies wereutilized.

Samples collected during the Phase II RI were submitted to the ETC in Edison, New Jersey. Laboratory analyses that utilize CLP methodologies, where applicable, were performed by ETC. Some samples collected during the Phase II RI required analysis for parameters that ETC doesnot have the capabilities to perform. These samples were subcontracted by ETC to alternativecertified analytical laboratories. The analytical parameters that required the services ofsubcontractor laboratories were asbestos, hexavalent chromium, grain-size analysis, and totalorganic carbon.

The laboratory Quality Assurance Project Plan (QAPP) prepared by ETC for the Phase II RI forthe Revere Chemical site was submitted to the USEPA prior to the initiation of field samplingand related laboratory analysis. A list identifying the subcontract laboratories to be used for thelaboratory analyses that could not be analyzed by ETC was also provided to USEPA for review. The laboratory QAPP and the subcontract laboratory lists were both approved by USEPA beforethe Phase II field investigation commenced.

Based on the quality assurance review, qualifier codes were placed next to specific sample resultsin the on-site and off-site contamination tables presented in the "Environmental Contaminationand Other Hazards" section. The PADOH believes that the qualifier codes provide an indicationof the qualitative and quantitative reliability of the data presented in this public healthassessment. The analyses and conclusions in this health assessment are valid only if thereferenced information is complete and reliable.

D. Physical and Other Hazards

Approximately 25 acres of the site, which contained the former process area, were observed to besecured with a chainlink fence. Several dilapidated buildings remain; however, they are notaccessible without gross trespassing violations.

PATHWAY ANALYSES

To determine whether residents are exposed to contaminants migrating from the site, PADOHand ATSDR evaluate the environmental and human components that lead to human exposure. Apathway consists of five elements: a source of contamination, transport through anenvironmental medium, a point of exposure, a route of human exposure, and a receptorpopulation.

PADOH and ATSDR identify exposure pathways as completed, potential or eliminated. Completed pathways include all five elements and indicate that exposure to a contaminant hasoccurred in the past, is currently occurring or will occur in the future. Potential pathways,however, have at least one of the five elements missing, but it could exist. Potential pathwaysindicate that exposure to a contaminant could have occurred in the past, could be occurring now,or could occur in the future. Eliminated pathways have at least one of the five elements missingand it will never be present. Completed and potential pathways, however, may be eliminatedwhen they are unlikely to be significant.

A. Completed Exposure Pathway

There are no known completed exposure pathways related to the site.

B. Potential Exposure Pathway

There is a remote potential for migration of on-site contaminants to migrate to off-site residentialwells. Site-related contamination is largely confined to the former process area. TCB was notdetected in any residential well tested and TCE was detected at an estimated 2 µg/L. Contamination to TCE and TCB was found in MW-4 in Phase II groundwater sampling at 110µg/L and 41 µg/L respectively. Neither TCE nor TCB were detected in the groundwater samplecollected from MW-11, which is located approximately 150 feet away from MW-4 in adowngradient direction. Nonetheless, there is a potential for these contaminants to migrate off-site and impact a small number of residential wells.

Lead was found in several off-site residential wells. The source of the lead contamination wasnot determined; however, it was not believed to be related to the site. The maximum leadconcentration was found in a well determined to be upgradient of the site. Household plumbingcould contribute to this contamination. This well was also found to have higher concentrationsof other organics not related to the site. The presence of lead is a public health concern and willbe discussed in the Public Health Implications section.

A detailed assessment of the hydrogeology at the site is necessary to determine if groundwatercontamination pathways can reach off-site residential wells.

The primary porosity and associated permeabilities of the Lockatong and Brunswick formationsare very low. However, the development of fractures in the bedrock can increase permeabilitythrough secondary porosity. Fractures in the Lockatong formation in the site vicinity provide apathway for groundwater migration through the local bedrock, resulting in the formation of aworkable aquifer (1).

The fracture trend analysis conducted during the Phase 1 RI identified two sets of preferredfracture orientations at the site. However, these fracture zones could not be traced across the site,and, in fact, were not identified in adjacent wells. Thus, the frequency of bedrock fracturesappears to be randomly distributed throughout the site, although preferred fracture orientationsexist at the site. In addition, the television surveys and geophysical analyses indicated thatgroundwater flow beneath the site is directed by both horizontal and vertical fractures (1).

The groundwater flow at the site has not been positively confirmed. This was reported in thePhase 1 RI when it was noted that the five monitoring wells in the process area did not providesufficient data for the construction of an accurate groundwater elevation contour map (2). Precise groundwater flow could not be ascertained through the Phase 2 study when additionalwells were installed. Consultation was received from the PADOH Hydrogeologist and he feltthat there was not sufficient wells at shallow, intermediate and deeper zones to properly assessgroundwater flow. His review of the hydrogeological maps provided and monitoring well dataindicated that information was insufficient to determine groundwater flow (11).

A Phase 2A Groundwater Investigation is underway. The Phase 2A scope of work focuses on: (1) confirming the source of recharge water that is producing the groundwater mound,(2) evaluating static groundwater flow conditions, and (3) confirming the limited extent anddegree of compounds detected in two of the groundwater monitoring wells. This will includeresidential well sampling near the site.

A recent discussion with the USEPA Remedial Program Manager indicated that site-relatedcontaminants have not been found in recently tested off-site residential wells. However, thisstudy has not yet been finalized and summarized so that groundwater flow and residential wellsampling results remain a data gap until the Phase 2A investigation is complete and the findingsreviewed (12).

Groundwater contamination in on-site monitoring wells is not extensive; however, if anymigration of site contaminants is occurring, it would most likely occur in the wells west andsouthwest closest to the site. The number of persons potentially affected would be small. (SeeFigure 6).

There is a potential for TCE and TCB to migrate off-site; therefore, these contaminants will bediscussed in the Public Health Implications section.

The "process area" of the site is fenced and not accessible to the public. Soil contamination wasmostly limited to this area, and generally, repeated sampling rounds indicated that contaminantlevels decreased with distance from the process area. The spray fields are revegetated and themajority of samples taken from these areas were non-detect for VOCs and B/Ns. The soilpathway can be eliminated as a public health concern to off-site residents.

PUBLIC HEALTH IMPLICATIONS

A. Toxicologic Evaluation

Introduction

In this section, we will discuss the health effects in persons exposed to specific contaminants. The USEPA developed Maximum Contaminant Levels (MCLs) for drinking water. PrimaryMCLs are federal drinking water standards declared under the Safe Drinking Water Act. Generally, an MCL for a toxic chemical represents the allowable lifetime exposure to thecontaminant for a 70-kg adult who is assumed to ingest 2 liters of water per day. In addition tohealth factors, an MCL is required by law to reflect the technological and economic feasibility ofremoving the contaminant from the water supply. The limit set must be feasible given the bestavailable technology and treatment techniques. USEPA's Reference Dose (RfD) is an estimate ofthe daily exposure to a contaminant that is unlikely to cause adverse health effects. ATSDR hasdeveloped Minimal Risk Levels (MRLs) for contaminants commonly found at hazardous wastesites. The MRL is an estimate of daily human exposure to aa contaminant below which non-cancer, adverse health effects are unlikely to occur.

As mentioned in the Pathways Analysis section, there are three contaminants retained fortoxicological evaluation. They are lead, TCE and TCB.

Lead

Lead was found in one filtered sample at a level of 25.1 µg/L in a residential well. The currentMaximum Contaminant Level Goal (MCLG) for lead is zero. As previously indicated, anunfiltered sample is preferable to obtain actual levels ingested. While ATSDR has no MRLs andUSEPA has no RfD for lead, this lead exposure of 25.1 µg/L should be reduced to the lowestlevel possible (at least below USEPA's proposed guideline of 15 µg/L at the tap). High bloodlead levels are associated with a decrease in intelligence quotient (IQ) scores, slow growth andhearing problems. Lead exposure is especially dangerous for unborn children because they canbe harmed during fetal development. Pregnant women exposed to lead can transfer lead tounborn children, causing premature birth, low birthweight and miscarriages (13). The level oflead found in this residential well (25.1 µg/L) would not likely cause any of the adverse healthoutcomes cited above.

Trichloroethylene (TCE)

TCE exposure has not occurred and is not occurring to off-site residents via any media. Currently, there is no chronic MRL or RfD available for this chemical.

TCE was found in an on-site monitoring well at 110 µg/L; however, there was no indication thatthis TCE was migrating. In the event that the TCE found on-site would migrate to a residentialwell and if exposure occurs at that level, adverse health effects may occur from chronic exposure(e.g., cancer).

Occupational studies of workers exposed to TCE (levels which are much higher than the levelsfound in the environment) have not detected TCE-induced cancer, while some animal studieshave shown that TCE can produce lung and liver cancer (14). Animal studies also have shownthat TCE can cause leukemia, a cancer of the tissues that form white blood cells. In reviewingthe animal studies, the Department of Health and Human Services (DHHS) National ToxicologyProgram could not find clear evidence that TCE causes cancer in animals. The InternationalAgency for Research on Cancer (IARC), an agency which classifies chemicals for theircarcinogenicity, has decided that TCE is not classifiable as to human carcinogenicity. USEPA,which also classifies the carcinogenicity of chemicals, classified TCE as a probable humancarcinogen. However, USEPA is currently reviewing the carcinogenicity of TCE. There isuncertainty prevailing among the scientific community with regard to the carcinogenicity of thischemical.

The nervous system is probably the most sensitive system that will show adverse health effectsfrom chronic exposure to TCE (12). However, it is unlikely that this health effect would occur at the level detected on-site.

1,2,4-Trichlorobenzene

There has been no known human exposure to 1,2,4-trichlorobenzene (TCB) related to the RevereChemical site. However, TCB was found in MW-4 on-site at a concentration of 41 µg/L. Theproposed MCL is 9 µg/L. If TCB migrates to off-site residential wells and if exposure occurs atthe level found on-site, then some health effects can occur (e.g. irritation of skin, nose and throat)(15).

There is no evidence that TCB is migrating and even if no further remediation is done on-site,regular testing of nearby residential wells should prevent any exposure that would cause adversehealth effects.

B. Health Outcome Data Evaluation

All residents in the vicinity of the site depend on private wells for their water supply. There wasno evidence of site-related contaminants in the closest well to the site (Cotner Trailer). Therewere no site-related contaminants of concern in several residential wells that were recommendedfor a retest in the RI/FS. There were no community concerns associated with morbidity ormortality so no health outcome data bases were evaluated.

C. Community Health Concerns Evaluation

We have addressed the community concerns about health as follows:

    What are our health risks from drinking from a private well in close proximity to the site?

    No residential well sampled during the Remedial Investigation or during the GroundwaterFeasibility Study has contained definite site-related contaminants at levels of public healthconcern. TCE has been noted in several wells at low concentrations of 2-3 µg/L. One filteredsample contained lead at 25.1 µg/L and was believed not related to the site. Another residentialwell reported 7 µg/L for lead during a recent test (10). These residents should be informed of the current guidelines for lead contamination. Public health education should be provided to arearesidents as to how to minimize lead exposure if the origin is household plumbing. Discernibleadverse health effects are unlikely at these exposure levels; however, the lead exposure should bereduced preferable to zero.


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