L>tP,\RTMLNT OF HEALTH 1 til V1-AN SERVICES".. ., "." \ '. . /: ' .... . .._ . ..Public Health Service

Agency foi Tox-c.Subsia.ncesand Disease Registry

Atlanta.GA.30333 '. . .;=.

APR 20 1989

Mr. Abraham Ferdas LAssistant Chief - - - . ;""-Superfund BranchHazardous Waste Management DivisionRegion III ' ~~i " . " ~" - "-"-"-841 Chestnut Building ;Philadelphia, Pennsylvania 19107 ;

Dear Mr.. Ferdas:

Enclosed are three copies of the completed Health Assessments on thefollowing sites prepared by the Office of Health Assessment, ATSDR:

Army Creek Landfill National Priorities List (NPL) SiteDelaware Sand & Gravel Landfill National Priorities List (NPL) Site

We have received and taken into account your comments on the draftdocument previously sent to your Regional Office. We very much appreciateyour comments and look forward to working with you and your staff in thefuture.

Sincerely yours,

Stephen D. Von AllmenAssistant Director for HealthAssessment Coordination

Office of Health Assessment

Enclosures

RR3000'06

assessment•&"&si*tt.->*xrjv#<l'r ••*--. r-J, . ^ v. . - Wa ^ . ^ -.T*

NEW CASTLE COUNTY, DELAWARE

CERCLIS No. DED000605972

Agency for Toxic Substances and Disease. RegistryU.S. Public Health Service. ~ r"

SUMMARY ;

The Delaware Sand & Gravel Landfill NPL site is in New Castle <3ounty.Delaware, approximately two miles southwest of the City of New Castle.The property is adjacent to the Army Creek landfill NPL site, and remedial.planning for both sites is being coordinated so that corrective measuresare compatible and effective. Contaminants of principal concern arevolatile organic compounds and heavy metals. The .site is located in asparsely populated area. However, there are a number of residences andbusinesses located next to the site, and there is a housing developmentapproximately one-telf mile away. The principal potential public healthconcern is for contaminated groundwater and its effect on a public watersupply well field downgradient from the landfill sites. A groundwaterrecovery system, to date, has prevented potentially extensiveccintamination of the public water supply (well field); and proposedremedial measures are expected to improve groundwater quality. This site,without remediation, is of potential health concern because of the risk tohuman health resulting from possible exposure to hazardous substances atconcentrations that may result in adverse health effects. .

BACKGROUND

A. SHE DESCRIPTION ;

The Delaware Sand & Gravel Landfill (DSGL) site is in New pastle County,Delaware, approximately two miles southwest of the City of' New Castle.The site is included on the National Priorities List (NPL). A Record ofDecision (ROD) was prepared jointly by the State of Delaware and the tr. S.Environmental Protection Agency (EPA) in April 1988. The DSGL site isadjacent to the Army Creek Landfill (ACL) NPL site, and remedial planningfor both sites is being coordinated so that corrective measures arecornpatible and effective.

The site was initially operated as a sand and gravel quarry. Wastedisposal began, on a permitted basis, in 1968 and continued until 1976when the state juiitiated enforcement action. Wastes are located in fourareas, comprising about 12 acres, on a site of approximately 27 acres.The waste areas are referred to as the Drum Disposal, Inert Disposal,Ridge, and Grantham South areas. Wastes include household andconstruction materials and approximately 7,000 drums containing industrialli<guids and sludges from plastic, paint, and petroleum refiningprocesses. There is no site security fence to prevent unauthorized entry.

The ACL site is to the west of DSGL, immediately across Army Creek. Thisfacility received municipal wastes from 1960 until closure in 1968. TheAmoco Asbestos Landfill is nearby, to the east of the DSGL site; and the

flR300008Page 1

Harry Wood landfill is approximately one-half mile to the north. At thistime, there is no evidence that contaminant migration, which might beassociated with either the Amoco or Wood landfills, have jbnnpacted the ACLand DSGL sites.

Investigations in the area began as early as 1971 when contamination ofwell water from a residential well southwest of the ACL site wasdetected* Soon after, New Castle County installed a groundwater recoverysystem designed to capture contaminated groundwater from both the DSGL andACL sites and prevent its encroachment on area wells, including theArtesian Water Company's public water supply well field to the south ofthe property. In 1984, approximately 600 drums were removed from thesurface of the Drum Disposal Area. Hie area was then covered with soiland revegetated.

One RX> issued for DSGL proposes to implement the following actions:

* Drum Disposal and Ridge Areas—Excavate wastes and contaminated soiland treat them by on-site incineration.

* Grantham South Area—Construct a multi-layered cap.

* Inert Disposal Area—Remove debris and construct a soil cover.

* Qroundwater—Continue recovery of contaminated groundwater and developa system for treating the water prior to its discharge into ArmyCreek.

For purposes of this Health Assessment, the Agency for Toxic Substancesand Disease Registry (ATSDR) assumes that vents will be provided toprotect landfill caps from possible rupture by gas accumulation.

Ine HDD for the ACL site (issued September 1986) proposes construction ofa cap at that landfill and continued operation of groundwater recoverysystem* Groundwater diversion may be initiated at a segment of thelandfill if that becomes necessary to prevent groundwater from flowinglaterally through a portion of the landfill wastes. The ROD alsoindicates that treatment for recovered groundwater and remedial measuresfor sediments in Army Creek are to be addressed in a future ROD. Sheremedial activities described in the ESGL and ACL RDD's have not yet beeninitiated for either site, except for ongoing groundwater withdrawal.

B. SITE VISIT

ATSER has not conducted a site visit to date.

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EN\m*ONMENTAL CQNTAMINAiriCN AND PHYSICAL HAZARDS

A. CN-SHE

Monitoring data that illustrate contaminant levels in on-site g]:oundwaterand surface soils are presented in Table 1, in the Appendices.

B. OFF-SITE OOMEAMINftnClN

Several organizations have conducted monitoring programs off-site,beginning in 1972. Table 2, in the Appendices, summarizes important datacollected from 1983 through 1986 for the ACL and DSGL sites forcontaminants in groundwater nonitoring and recovery wells, in public watersupply and industrial wells, and in Army Creek water and sediments.

C. HBTSICAL HAZARDS

1 11s with wastes that have an appreciable organic content mygenerate methane which, in the presence of an ignition source, can beexplosive when it accumulates in an enclosure, such as within a landfillcap and vents or in buildings*

. DEMDGRAffflCS •-

e DSGL site is located in a sparsely populated and lightlyindustrialized area south of the City of New Castle. 3he landf jj.1 is atthe end of Grantham lane and adjacent to Army Creek. Along Grantham lanethere are about 10 residences, a private health club and recreation field,soue small businesses, and offices for the State of Delaware Division ofAir and Waste Management. Properties adjoining the site include tworesidences, the health club and ball field, and a maintenance garage. Ohenearest residence is approximately 30 feet from the edge of the landfill.There are other residences and small businesses south and southeast of thesite, along Route 9; and the Ilangollen Estates housing development isabout one-half mile southwest of the property- All of the residences andbusinesses in the site area are supplied with public water by the ArtesianWater Company, which serves approximately 5,000 customers.

EWOUATION

A. SITE CHARAdEEaZATION (DATA NEEDS AND EVALUATION)

1. Environmental Media .

Investigation data gathered for site characterization have been fairlyextensive. However additional information is necessary to clarify whethersurface runoff and wind have deposited contaminants on surface spoils atnearby residences and businesses and the athletic field at levelspose a threat to health. Data or other information also are

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evaluate whether cx&isuming potentially contaminated fish from Array Creekor garden produce from potentially contaminated soil may be a healthconcern. After the landfill caps are in place periodic monitoring shouldbe considered to determine where and whether or not levels of methane orother gases released throue#i vents or subsurface strata pose a safety orhealth threat.

2. Demographics and land Use

Informaticn available in reference materials concerning demographics andland use is satisfactory for purposes of this Health Assessment.

3. Quality Assurance and Quality Control

AOSER presumes that analytical data have been reviewed by EEA and have mettheir acceptability criteria. Tne validity of the conclusions drawn inthis Health Assessment is determined by the reliability of the referenceinformation.

B. ENVIRONMENTAL PATHWAYS

Contaminants associated with the wastes that have been disposed at thesite have migrated into the soils, to the groundwater, and into Army Creekwaters and sediments.

Botii the DSGL and the adjacent ACL have released cont miinants that havemigrated to groundwater. Tfoe proposed waste and soil removal and capconstruction at DSGL, cap construction at ACL should significantly reducethe quantities of contaminants entering groundwater. The geologic —features of principal importance to groundwater contaminant movement inthe vicinity of these sites include:

* The Columbia Formation, a sandy water-table aquifer on which thelandfills have been developed.

* Zones of low permeability silt/clay in the Upper PotomacFormation, immediately beneath the Columbia aquifer, that serveas an aquitard which hydraulically separates the ColumbiaFormation from deeper aquifer zones. Tnese silts and clays arediscontinuous and non-uniform; and in some places the sands ofthe Columbia and Potomac are in contact. For example, these lowpermeability materials appear to be absent in the area betweenthe DSGL and ACL sites.

* Aquifers within the Potomac Formation. Ihe uppermost PotomacAquifer, called the Upper Potomac Hydrologic Zone (UHE), is theaquifer of principal concern.

Locally, the grcurdwater within the Columbia is derived from infiltrationof rain water, and infiltration from Army Creek and a drainage ditch.Some of the water and entrained containinants that enter the ColumbiaFormation discharge directly into the underlying UfflZ within the area

Page 4

R30

where there are no intervening silt/day members. Major factors affectinggncundwater flow and contaminant migration near the DSGL and ACL includeAnny Creek, non-aguitard areas (e.g. , between the landfills) , andgroundwater withdrawals associated with the Artesian Water Goirgpany (AWC)well field, and the groundwater remediation recovery well system. Iheflow regime in the TOHZ near the landfill has changed over time* Prior to1952, groundwater movement was predominantly to the west. However, sincethen, groundwater has flowed to the southeast, east, south, west, andscuthwest at various times. After waste disposal began (1960 for ACL;1968 for DSGL) , contaminants were transported by groundwater in thosedifferent directions. A westerly flow pattern has predominated since1982, following installation of five additional recovery wells. Becauseof the close proximity of the ACL and DSGL sites and the historicalvariations in groundwater movement, it has not been practical tx> confirm

site is the origin of specific contaminants.

Continuing groundwater monitoring in the area indicates that the recoverysystem has been effective in controlling groundwater contaminant migrationoriginating frcta both landfills. EPA Region HI, maintains that the 3WCwesll field is hydraulically isolated fraa the contamination as a result ofthe grcundwater divide created by the operation of the recovery wellnetwork, and AfKT's adherence to its permit conditions [withdrawal of up to2 million gallons per day (M3D) ] . Although, grcundwater monitoring fromindividual wells making up the water cctnpany well field has shewn1,2-dicfaloroethane in raw water at a concentration that exceeds the EE&'smaximum contaminant level (MCL) . However, the contaminant has not beendetected in finished water above the MCL.

Monitoring data indicate that landfill contaminants are present, in surfaceand subsurface soils on-site. Some of these constituents are likely tovolatilize to ambient air or to leach into groundwater. Contaminants atthe landfill surface also may become entrained by air currents andtransported to areas off-site. Remedial excavation activities planned fortwo of the landfill units are likely to release volatile and othercontaminants to the air. After the other Grantham South area has beencapped tiiis transport mechanism should be greatly reduced if noteliminated. However, there is an increased potential that elevatedconcentrations of methane and gaseous contaminants might be transportedoff-site through vents in the caps or through sand members below ground.

Without a properly constructed and maintained cover or cap, rainfallrunoff also is likely to transport some (e.g., non-volatile) surficialsoil contaminants off -site to adjacent properties and to Army Creek, whichdischarges into the Delaware River a few thousand feet downstream.Presently, water withdrawn by the groundwater recovery system also isreleased, without treatment, into Army Creek. Some of the contaminantshave been retained in creek sediments, and the remainder may be carried bytony Creek water to the river.

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Reference documents do not identify any specific food-chain species whichmight be relevant to the DSGL site* However it is possible that fish inArray Creek have bioconcentrated contaminants discharged with surfacerunoff and recovery-system water. Garden produce grown in contaminatedsoil at nearby residences also may be impacted as a result of off-sitecontaminant migration from site releases.

C. BUH&H EXPOSURE PATHWAYS

The most important potential human exposure pathway is through ingestionof groundwater which has become contaminated by site releases and is usedas the potable water supply for 5,000 customers in the vicinity of the twolandfills. A sunraary of human exposure pathways is provided in Table 3,in the Appendices.

FUBttC HEAIHH IMPUCKTIONS

Contaminants have been detected in groundwater from monitoring wellson-site and off-site, in off-site groundwater from recovery wells, and inraw water from pablic water supply wells at levels that are of healthconcern. Shere are no on-site water supply wells, so there is no exposurepossible on-site. Therefore, contaminated groundwater on-site does notpose a public health threat.

It is expected that multiple changes in groundwater flow directions aroundthe ACE, and DSGL sites have resulted in considerable intermixing of thecontaminants released at each location. In off-site groundwatermonitoring and recovery wells; benzene, trichloroethene,!,2-dic3ilQroethane, lead, and mercury have been found at concentrationsthat exceed regulatory maximum contaminant levels (MCDs) or recommendedmaximum contaminant levels (EMds). Benzene has been recorded at levelsup to 150 parts per billion (P3±>) and trichloroethene as high as 140 ppb.Concentrations of 1,2-Dichloroethane have been as great as 51.0 ppb, andlead has been found to 770 ppfo. Mercury concentrations have been as muchas 7.2 ppb. Water from these wells is not withdrawn for humanconsumption; therefore, there is no current public healtii threatassociated with groundwater at these locations. However, recovered wateris discharged to Army Creek where there may be exposure throughconsumption of cxaitaminated fish or recreational use of contaminatedsurface water.

EPA Region HI, maintains that the AWC well field is hydraulicallyisolated from the cxaitamination as a result of the groundwater dividecreated by the operation of the recovery well network, and MflC's adherenceto its permit conditions (withdrawal of up to 2 M3D). However, it is alsopossible that sane of the groundwater and entrained contaminants maybypass the recovery system and further threaten the quality of waterwithdrawn by the public water supply well system to the south. Monitoringconducted in grtxmdwater form AWC wells has detected l,2-d chlorQBE|ih«aa n n i o

Page 6

(maximum 11.0 ppb) in raw water at levels greater than its MCL* Ixang-terracxsnsumption of the raw water could pose a health threat; however,monitoring of the finished water that was being distributed through thepublic water system did not show any contaminant levels above MCL or EM£Lvalues.

Migration of groundwater contantination will continue to pose a potentialthreat to human health at least in the near future; but that threat shouldbe reduced over time, after remedial programs at both NPL sites; have beencompleted and which should result in further groundwater improvement.These remedial programs include measures designed to substantially, reducecontaminant releases to groundwater, to control and recover migratingcontaminants, and to monitor water quality and recovery effectiveness.

Surface water ingestion and dermal contact associated with possiblerecreational users of Army Creek do not appear to pose a public healthproblem at the contaminant (concentrations identified by monitoring.However, ingestion of sediment, during recreational use of the creek,might be a problem because of arsenic was detected at concentrationsranging up to 13,540 ppfo. Also, lead concentrations as hicjh as175,000 ppfo were recorded. 3he potential threat to human health should bediminished considerably after the landfill cap is in place, the treatmentsystem for recovered water being discharged to the creek is in operation,and contaminated sediments have been remediated.

Monitoring data for on-site soils at the DSGL site indicate contaminationlevels which may pose a potential threat to the health of intruders andunprotected remedial workers via ingestion. Polychlorinated bijohenyls(KB's) were detected in surficial soils as hi$i as 49,000 ppb, and —dibenzofurans were found at 14,000 ppb. lead concentrations ranged to5,400,000 ppb and arsenic to 92,000 ppb. Chromium was found up to222!,000 ppb and mercury to 2,700 ppb. Intruders may be potentiallyexposed, to these levels of contaminants until cap construction iscompleted. Remedial workers also may be at risk of physical injury ifappropriate safety procedures are not followed. With waste and soilremoval completed at the two landfill units and with caps in pleice at theother two units, the threat to human health from on-site soils eind wastesshould be minimal* However, any intruders might be exposed to gaseouscontaminants emitted through vents at concentrations that could pose apwblic health concern—or, for methane, a physical hazard because of itsexplosive characteristics.

Ihere are a number of health issues for which the level of concern cannotbe evaluated because related contaminant information is not available orcannot be developed at this time. Surface soils off-site at the adjacentresidences, businesses, and athletic field could pose a threat to humanhealth if runoff and air transport from the landfill have depositedsignificant amount of contaminants at those locations. Construction ofcaps over two landfill areas may result in exposure for intruders ornearby residents and unprotected workers to releases of methane or gaseous

AR3000U

cxaitaminants either through vents or throu i subsurface strata. Fi i andgarden produce possibly may bioconcentrate released site contaminants fromtheir environment to levels that might pose'a threat to those who consumethem.

OONOIJSIONS AND KECXMffiNDKTCCNS *

A.Ihis site may be of potential health concern because of the risk to bumanhealth resulting from possible exposure to hazardous substances atconcentrations that may result in adverse health effects* As noted in theHuman Exposure Pathways section above, human exposure to contaminants maybe occurring. Hhe public water supply which originates from groundwaterwithdrawn dcwngrs ient of the DSGL and ACL facilities could pose a publichealth threat if cxantaminants occur in finished water at concentrationsabove applicable standards. In addition, intruders on-site and adjacentoff-site residents and workers may be exposed to contaminants in soil andair at levels of health concern. Contaminants released during remediationcould be at concentrations that may adversely affect human health.Persons using the creek for recreational purposes may be exposed tocontaminants in sediment and surface water, and persons consuming fish andgarden produce also may be exposed. After the landfill caps are in place,there may be exposure to methane and gaseous contaminants at levels thatmay pose a threat to safety and health..

B. KEOTfcENDZOTCtJS

1. In accordance with CERCLA as amended, the Delaware Sand and Gravellandfill NPL site, New Castle County, Delaware has been evaluated forappropriate follow-up with respect to health effects studies.Inasmuch as there is no extant documentation or indication, in theinformation and data reviewed for this Health Assessment, that huoanexposure to on-site or off-site cxsntaminants is currently occurringand there are no tests to evaluate past exposures, this site is notbeing considered for follow-up health studies at this time. However,if data become available suggesting that human exposure to significantlevels of hazardous substances is currently occurring or has occurredin the past, ATSER will reevaluate this site for any indicatedfollow- up.

2. 325CR concurs with the RQD's proposal to continue monitoring todetermine the effectiveness of the remedial action on groundwaterquality. Monitoring for finished water delivered to Artesian WaterCompany customers must include pertinent (site related) contaminantsand must be capable of detecting changes in water quality that mightresult from variations in individual well output (e.g. , well outages,resource management) . It also would be appropriate to consider tfceuse of institutional controls to prevent installation of water supplywells into contaminated portions of the aquifers until theis inproved to drinking-water quality.

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3* Hie proposed system for treating groundwater before it is dischargedinto Army Creek should be designed and operated so that contaminantsdischarged to the environment are below 'levels of health concern.Monitoring should be conducted in any environmental media throughwhich public health could be adversely affected by the discharges inorder to develop an appropriate data base to evaluate any healthconcern.

4. Consider surface soil monitoring on adjacent properties to evaluateany potential health concerns.

5. After the landfill caps are in place, periodic monitoring is needed todetermine whether there are public health or hazard concerns relatedto releases at vents and also in enclosed (e.g., basement) portions ofadjacent buildings. _

6. Consider preventing unauthorized entry onto the landfill areas tominimize the potential for on-site exposure.

7. Consider conducting real-time air quality monitoring during remedialactivities to ensure that persons on-site and off-site are not exposedto unacceptable levels of contaminants released to the air duringexcavation and treatment of contaminated materials. ;

8. Monitoring data or other information (e.g., a wildlife consumptionsurvey) should be considered to evaluate whether consuming fish fromArmy Creek or garden produce grown in potentially contaminaized nearbysoils poses a threat to health. ;

9. Remedial workers should adhere to applicable regulations andrecxramendations outlined by the Occupational Safety and HealthAdministration and National Institute for Occupational Safety andHealth. ;

I10. A2SCR concurs with the intended further evaluation of Army Creek

sediments. !

PKEPARERS OF REPORT | -

iReviewer: Don Gibeaut

Environmental Health EngineerEnvironmental Engineering Branch

Typist: Charlotta V. GavinClerk Typist ;Environmental Engineering Branch

Regional Representative: Nicholas J. DiNardo , a p O fj fl flPublic Health Advisor H R O U U URegion III rField Operations Branch

Page 9 !

REFERENCES

1. Durm Geoscience Corporatdoi, 1987, Remedial Investigation, DelawareSand and Gravel Tanti-Fill

2. Durm Geoscience Corporation, 1988, Feasibility Study, Delaware Sandand Gravel landfill

3. USEPA, 1988, Record of Decision, Delaware Sand and Gravel Site

4* Weston, 1986, Feasibility study, Amy Creek Landfill

5. U3EPA, 1986, Record of Decision, Array Creek landfill

6. AOSCR Files

APPENDICES

Table 1 On-Site Contaminants of Potential Concern

Table 2 Off-Site Contaminants of Potential Concern

Table 3 Human Exposure Pathways

flR3000!7Page 10

TABLE 1

ON-SHE CONTSMINANIS OF POTENTIAL CONCERN

OTCX3NDWA3ERWEI1S

Ethyl Benzene ND - 1,100Benzene ND - 3,100Toluene ND - 8,700O ricfcloroethene ND - 3201,2-Dichloroethane ND - 93.0Arsenic NDCadmium NDCtocmium NDlaad ND - 1,370Mercury ND

SURFACE sortsEthyl Benzene NDBenzene ,*" NRToluene ND - 120Trichloroethene ND - 250 (a)1,2-Dichloroethane NRDlbenzofuran ND - 14,000 (a)PCB-1254 ND - 49,000PCB-1260 ND - 210 (a)Arsenic ND - 92,000Cadmium ND - 29,000OHrunium ND - 222,000Lead ND - 5,400,000Mercury ND - 2,700

No surface water bodies on-siteSampling conducted 1985, 1986ND - Not detectedNR - No data reporteda - Detected in one sample

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TABLE 2

OFF-SZCE CXimmENaNTS OF POlibWJilAL CONCERN

taftrt ___________ __KJBUC WATER INDDSTRIAL

SUPPLY WETTS (c) WBT.TSEthyl Benzene ND - 690 ND NDBenzene ND - 1500 ND NDToluene ND - 8700 ND " NDTricMcsroethene ND - 140 ND ND1,2-Didilaroethane ND - 51,0 ND - 11.0 NDArsenic ND - 24.6 ND NDCadmium ND - 1.5 ND NDQiroaiuni ND - 37.3 ND - 9.5 NDlead ND - 770 ND - 11.0 NDMercury ND - 7.2 ND ND

fiEMST. CREEK..

Ethyl Benzene ND NDBenzene ' ND NDToluene ND NDTricMoroethem ND NDl,2-Dichlc(roethane ND , NDArsenic ._ . ND ND - 13,540Cadmium ND - 1.5 NDChromium ND - 17.6 ND - 25,540lead ND - 7.7 ND - 175,000Mercury ND - 2.0 ND - 630

Sampling conducted 1983, 1984, 1985, 1986No data for off-site soilsND - Not detectedNR - No data reporteda - Detected in one sampleb - Monitoring data from wells installed for the Sand & Gravel NFL

site "and from sore of the wells installed for the adjacentArmy Creek NPL site.

c - Artesian Water Company wells that provide public water supplyto 5,000 customers, including all users in the site vicinity.

SR3000I9

MEDIA POTENTIAL EXPOSURE POINTS EXPOSURE BOOTES OF OQNCEBH [Y/N]E

SOIL OW-SITE * Intruders onto Y * Ingestion, dermal contact.property possibly exposed.Proposed waste and soil removaland capping measures should • ' -reduce potential for futureexposure. ;* Unprotected remedial workers Y * Ingestion, dermal contact.possibly exposed.

OFF-SITE * Persons at adjacent Y * Ingestion, derma] contact.and nearby residences,businesses, and athletic facilitypossibly exposed to contaminantsthat may have migrated from thesite by air or runoff. Proposedwaste and soil removal and 'capping should reduce potential !for releases to off-site areas;and, with time, the potential forexposures should be reduced.

GROUND ON-SITE * No water-supply wells N * Not a current environmentalWATER on-site, no current exposure. pathway, no likely exposure

routes (future water-supply wellinstallation unlifcBly}.

OFE -sriB * Persons in the site Y * Ingestion, dermal contact, andvicinity use public water from also inhalation (volatilizedArtesian Water Conpany wells and groundwater contaminants duringmay have been exposed to low household use).concentrations of contaminants inthe groundwater. With time,waste cleanup and capping, alongwith continued groundwaterwithdrawal and treatment, shouldreduce the potential for . . . _ . . _ . .exposure.

Table Continued

1R300020

MEDIA.

SURFACEWATER,SEDIMENT

AIR

TABLE 3(Continued)

POTENTIAL EXPOSURE POINTS

ONH5ITE * No surface water bodiesor sediment on-site, no currentexposure.

OFTHSJLTK * Persons using ArmyCreek for fishing or recreationpossibly would be exposed.Proposed waste and soil removaland capping measures shouldreduce contaminant releases tosurface water and sediment? and,over time, the potential forexposure should diminish. If 'remediation is completed forcreek sediments and recovered

1 t • ii • • i i J « A - » - * . • A^ —groundwaLer is treated prior todischarge, the subsequentpotential for exposure should be

CN-Sl'lt! * Intruders possibly areexposed to airborne contaminantsvolatilized or entrained from theground surface. Proposed wasteand soil removal and cappingmeasures should reduce thepotential for exposure, .unlesselevated concentrations ofgaseous contaminants or methaneare emitted through vents.* Unprotected remedial workerspossibly may be exposed topwticulHt** und volatilecontaminants during cleanup.

EXPOSURE ROUTES OF CONCERN [Y/N]E«*<• ^ tT« In A * •• * - - J . 1 • • •• J ii • N * Not a current environmentalpathway, therefore, no exposureroutes.

Y * Ingestion, dermal contact,inhalation.

Y * Inhalation, ingestion(contaminants). Explosion,physical injury (methane)

Y * Inhalation, ingestion.

Table Continued —

AR30002I

TABLE 3(Continued)

MEDIA POTENTIAL EXPOSURE POINTS EXPOSURE BODIES OF CONCERN [Y/N]]

OFF-KLIU * Persons at residences, Y *• Inhalation, ingestionbusinesses, and athletic facility (contaminants). Explosion,off-site possibly are exposed to physical injury (methane).

Additional exposure possibly mayyygrp Airrtnrj remedial waste andsoil removal. Proposed waste andcoil removal and capping measuresshould reduce the potential forexposure, except for thepossibility that significant

itrations of gaseouscontaminants and methane might bereleased through landfill ventsor might be transported throughthe subsurface into nearby'buildings*

POOD ON-fel'AK * No likely exposure. N * Not a current environmentalCHAIN pathway, no exposure routes.

OFF-SITE * Any fish consumed from Y * Ingestion.the Army Creek, and garden

Y , produce grown at adjacentresidences might be contaminatedby site releases. Over time,proposed waste and soil removaland capping measures shouldreduce the potential forcontaminant migration. Whenremediation of creek sediments iscompleted and the recoveredgroundwater is treated beforedischarge, the subsequentpotential for these exposuresshould become even less.

Note*1: Y •= Rcute(s) potentially aN = Route (s) not of concern

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