V

APR 20|

Mr. Abraham FerdasAssiscanc ChiefSuperfund BranchHazardous Waste Management DivisionRegion III841 Chestnut BuildingPhiladelphia, 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) SiceDelaware Sand 6 Gravel Landfill National Priorities List (NPL) Sice

We have received and taken into account your comments on the drnftdocument previously senc Co 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 AllmenAssiscanc Direccor for Health

Assessment CoordinationOffice of Health Assessment

Enclosures

AR300lt90

ARMY CREEK LANDFILL NATIONAL PRIORITIES LIST (NPL) SITE

HEW CASTLE COUNTY, DELAWARE

CERCLIS No. DED980494496

Agency for To.v,' S.-1'.siaim1- ;.:. ' '.'•-U.S. Public He.; . N.-rvic.

SUMMARY

The Army Creek landfill NPL site is located in New Castle County,Delaware, approximately two miles southwest of the City of New Castle.The landfill is adjacent to the Delaware Sand & Gravel NPL site, andremedial measures for both sites are being coordinated- so that correctivemeasures are compatible and effective. Tne site is located in a sparselypopulated, lightly industrialized area. There are no residences adjacentto the site; however, a residential development is located several hundredfeet to the south. Volatile organic compounds and heavy metals ingroundwater are the principle contaminants of public health concern. Allresidences and businesses in the area are provided with public water froma well field (AWC) that is downgradient from the landfill sites. Agrounclwater recovery system, to date, appears to have averted potentiallyextensive contamination of the public water supply (i.e., well field); andproposed remedial measures are expected to improve groundwater quality.Ihis site, without remediation, may be of potential health concern becauseof the risk to human health resulting from possible exposure to hazardoussubstances at concentrations that may result in adverse health effects. .<

BACKGROUND

A, SITE DESCRIPTION

The Army Creek landfill (ACL) site is in New Castle County, Delaware,approximately two miles southwest of the City of New Castle. The site isincluded on the National Priorities List (NPL). A Record of Decision(ROD) was prepared by the U. S. Environmental Protection Agency (EPA) inSeptember 1986, and the State of Delaware concurred with the approvedremedy. The ACL site is adjacent to the Delaware Sand and Gravel Landfill(DSGL) NPL site, and remedial planning at both sites is being coordinatedso the corrective measures are conpatible and effective.

The ACL occupies about 64 acres that were formerly used as a sand andgravel pit. The site is not fenced, but there is a gate at the accessroad. Municipal refuse was disposed during the landfill's entire activelife (1960 to 1968). Investigations indicate wastes include paper, metal,glass, fabric, plastic, and wood.

To the east of the property, immediately across Array Creek, is the DSGLNPL site which operated from 1968 until 1976. Disposal there occurred infour areas, comprising about 12 acres, on a site of approximately 27acres. Wastes include household and construction materials andapproximately 7,000 drums containing industrial liquids, and sludges fromplastic, paint, and petroleum refining processes. The Amoco Asbestoslandfill is nearby, to the east of the DSLG site; and the Harry Wood

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AR300492

landfill is approximately one-half mile to the north. At this time, thereis no evidence that contaminants which might be associated with either theAnoco or Wood landfills have migrated to the ACL and DSGl sites.

Investigations in the area began as early as 1971 when contamination ofwellwater from'a residential well southwest of the ACL site was detected.Soon after, New Castle County installed a groundwater recovery systemdesigned to capture contaminated groundwater from both the DSGL and ACLsites and prevent its encroachment on area wells, including the ArtesianWater Company's public water supply well field to the south of theproperty.

The ROD outlines a two-phased remedy:

Fiase 1* Install a multi-layer cap over the landfill.* Continue operating the downgradient recovery well network.* Evaluate the effectiveness of the cap system and groundwater

recovery network for five years by monitoring well water levels,punping rates, and water quality,

ffiase 2* After the five-year evaluation period, determine whether it is

necessary to install upgradient controls to prevent lateralgroundwater flow into landfill wastes along the northwesternboundary.

* Continue monitoring well water levels, pumping rates, and waterquality as in Phase 1.

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

Ihe FDD indicates that a future FDD will address a specific treatmentmethod for recovered groundwater and appropriate remedial measures forsediments in Army Creek. Remedial measures outlined in the ACL and DSGLROD'S have not yet been initiated, except for continued groundwatermonitoring.

B. SITE VISIT

ATSDR has not conducted a site visit to date.

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AR3001»93

ENVIRONMENTAL CONTAMINATION AND PHYSICAL HAZARDS

A. ON-SITE OOTlMINATION

Monitoring conducted in the 1970' s indicates landfill leachate containsnumerous alcohol and acid compounds. Information regarding contaminantsin on-site soil and groundwater is not available in reference documents.However, ATSDR expects that the landfill would have released to theon-site soils, and groundwater the same types of organic compounds andinorganic constituents that are found in off-site groundwater monitoringand recovery wells, as recorded in Table 1.B. OFF-SITE CONTAMINATION

Several organizations have conducted monitoring programs off-site,beginning in 1972. Table 1, in the Appendices, summarizes important datacollected from 1983 through 1986 for the ACL and CSGL sites, forcontaminants in groundwater monitoring and recovery wells, in public watersupply and industrial wells, and in Amy Creek water and sediments.

C. PHYSICAL HAZARDS

landfills with municipal wastes that have an appreciable organic contentnay generate methane which, in the presence of an ignition source, can beexplosive when it accumulates in an enclosure, such as within a landfillcap system and vents or in buildings.

DEtCGRAHHCS

The ACL site is located in a sparsely populated and lightly industrializedarea south of the City of New Castle. The landfill is bordered on thenorth by the Perm Central Railroad and, beyond the railroad, by a sand andgravel company. Army creek, a tributary of the Delaware River, lies alongthe south edge of the landfill. The DSGL NPL site is a few hundred feeteast, beyond Army Creek. Llangollen Estates, a residential development,is several hundred feet beyond the southern edge of the ACL site, Thereare no residences close to the facility, although a few houses andbusinesses are some distance to the west, east, south, and southeast. Allof the residences and businesses in the site vicinity are supplied withpublic water by the Artesian Water Company, which serves 5,000 customersin the area.

EVALUATION

A. SITE CHARACTERIZATION (DATA NEEDS AND EVALUATION)

1. Environmental Media

Investigation data gathered for site characterization have been fairlyextensive. However, data or other information are needed to evaluatewhether consuming fish from Array Creek nuy fcc a health concern. Also,

Page 3

after the landfill cap ia in pl.vx, \nr\rj\V. ,"r,r.iv>rl/f/ 11 /iu.r'jj,rl.V/ideteroine where and wtxrthor or TO* m'/w or '/i/yirreleased thra i verits, powi .1 wiJi'ty f;r //Mi'./i %/,r»',r

2. Demographics nrrl I/NT! 1,'rxi

Information nvallablo in rcfornrrxi rWJirUU ar/rifwnlr// 'tmr/ffifM'<«land use Is satisfactory for fnrf«w,-i 'if 'Ma

3. Quality Aasvirnnoo .v»J

A15CR pn»ns3 that invwitl'pu™ /)•.*. ivi'.ln'i /inl /iwl/' U/ii -Ui'd Mv« i««r,reviewed b/ EPA arrt h.ivn not t//t>r /vj.Dj Mll'.y rrl'xtli, 'Iti" yillrll'/of the ooncliwiCTO drawn in Uiln IMMh Aflwwrr,' It 'l«'nrmlf^»l 17 ff,«reliability of tho rofcrcrcfl ir..'nrr,r.l',ri.

B. aivrra EfrA trawiv:;COnt/yninint t aso;<:inUvt witr. U/i V.I 'AI.T ',1,1'. i,r/n I' fi 'lln|fi'«! .1' 'f,nsite (MVO nitjrat/.iJ i;;Ui Uw notln, 'A- '/i ' ''ui .i'pf, ir<i 1-,'u ^1,7 nt*?w.Uurs and

Both the Ad. nrrl ndjoconr. '!''"'„ (vivo rfi!"/ir ! (.T.rfA'lf/ifi'.i 'Ki' i»rvnnigratod to Troat tcr. 'Hit pr.;/.«vri /-/iji '.nr«i'r.».r* l-n /\" A/'!, .url wn'orwrwvnl «nd cvip ajnntr.jcxicn nt. I/-;;. nr.viM ni'/ril fl-'.ir,' ly l»^l n finqviantitica of oontA'ironta pr.':orif»| -jrviff|..'.i'oc. 'It" 'ir"l"|l" f"dtiunn 'ifprincipal irpsrtflmn tr> f/nrMiiUi1,"! i.r.r.' .-1/.in* rrvTrr,* In n,o '/i.-mi'yof those Ritor. incloloi

HIQ Colurhin I'oir.it l',n, nlarrlfilln Ivivn l.wn <)(r/p !';;»•< I,Zoncn of lew poiTuMUltty niH.p''j.iy l/i ir;n i^nc |'.M",\ .•FoiTiition, IrrrrllnlPly l*'!/vr/) M/i 'MTltU fl'filf"! , 'l.if wr/n«a MI ncjMiUinl vMdi liyUn'ill'.vill,' M'jrtinUn f;,i» 'y.l nM-iFormtlon fnn dwfinr n-fiid-r ."-.I/M. 'I1;*rn n i l ' n /ir»| r i^yi IMPdincontirniam wrl iMi-M/ilf';!r; >vil In turn pli '•*< 'fi« •unl'i 'iftho CtilitTtoln (\nl IWT.lt; nin Id (.i,f,',v.t, f'il c/'iirjiln, fh««« I'NpamoAbllity imtorlnln nu^ir i(, t«> nlr^rit In if," ii^.i l»''nwntho DCGI, nrrl AG. nltrn.Afjuifcrn within tlm l«jU.mf.' fi)i7',i' i';ii, Hi" u|vi"T"1" I'l rivAquifer, called Uw llyrr 1'iUnv: ir,'liTiUf|l': i1 .•,!/•• C'!M/|, It t(i«ntjuifor of prirr:i[ol aurrm,

y, th« grwirri.i'ntflr wiUiln itii Cr,li.r/.l/i In ilnlvnl fi'ti I n t l l t i V l"nof rain wntor, arri Inf lltcntloti ii-.n Air/ i.'i'w): ir»l n 'Inili.vi" 'llfdi,Somo of tho Victor nrrl ontrnlix'l (.wi'flrlMnf.'i U' it rn'rc H^ 'niimliUFoniwtion diccJv\rt;o dlrrct.ly In'o tl," uirl"i-lyiri| I'!H,'. wlfMn tfi« HIMwhoro thorn nrn no int.nwniirj nllt/i'Uy rrri«'iTi, l'.\)"t f.v.-tnm /iffn* lingrawttwntor flew nrrl roriUr.ir.v/ r.l'fi'iti' n Cif.ir A''l. ntil frv;;, Irrlnl" AirvCrocX, non-nqviiUt'.! (IITMS (n,i|. , l«t'.iT'i if," Inntf ill-ii , '"il 'if"in^if''i

withdrawals associated with the Artesian Water Company (AWC) well field,and the groundwater remediation recovery well system. ihe flew regime inthe UPHZ near the landfill has changed over time. Prior to 1952,groundwater movement was predominantly to the west. However, since t'.iengroundwater has flowed to the southeast, east, south, west, and southwestat various times. After waste disposal began (1960 for ACL; 1968 forDSGL), contaminants were transported by grcundwater in those differentdirections. A westerly flow pattern has predominated since 1982,following installation of five additional recovery wells. Because of theclose proximity of the ACL and DSGL sites and the historical variations ingroundwater movement, it has not been practical to confirm which site isthe origin of specific contaminants.

Continuing groundwater monitoring in the area indicates that the recoverysystem has been effective in controlling groundwater contaminant migrationoriginating from both landfills. Although well water monitoring fromindividual wells making up the water ccmpany well field has shown1,2-dichloroethane at a concentration that exceeds the EPA's maximumcontaminant level (MCL), the contaminant has not been detected in finishedwater above the MCL. Further, EPA Region III, maintains that the AWC well'field is hydraulically isolated from the aquifer contamination as a resultof the groundwater divide created by the recovery well network, and AWC'sadherence to its permit conditions [withdrawal of up to 2 million gallonsper day, (MGD) ].landfill contaminants are present in surface and subsurface soilson-site. As a result, some constituents are liXely to volatilize toambient air or to leach into groundwater. Contaminated soil particles andvolatiles at the landfill surface also may become entrained by aircurrents and transported to areas off-site. After the cap is in placethis transport mechanism should greatly reduced. However, there is anincreased potential that elevated concentrations of methane and gaseouscontaminants might be transported off-site either through vents in the capor through sand members below ground.

Without a properly constructed and maintained cap, rainfall runoff also islikely to transport some (e.g., non-volatile compounds) surficial soilcontaminants 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 byArmy creek water to the river.

Reference documents do not identify any specific food-chain species whichmight be relevant to the ACL site. However, it is possible that fish inArmy Creek have bioconcentrated contaminants discharged with surfacerunoff and recovery well waters. Residences are not likely to havereceived contaminants via surface runoff and probably are not near enoughto have received airborne contaminants, either.

Pnge 5

flR300l«96

C. HUMAN EXPOSURE PAOHWAYS

Ihe 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 summary of human exposure pathways is provided in Table 2,in the Appendices.

PUBUC HEAiaH mPIICAHONS

Contaminants have been detected in groundwater monitoring wells off-site,in off-site ground water recovery wells, and in raw waters from publicwater supply wells at levels that are of health concern. There are noon-site water supply wells, so there is no exposure possible on-site.Therefore, contaminated groundwater on-site does not pose a public healththreat.It is expected that multiple changes in groundwater flow directions aroundthe ACL and DSGL sites has resulted in considerable intermixing of thecontaminants released at each location. In off-site groundwatermonitoring and recovery wells; benzene, trichloroethene,1,2-dichloroethane, lead, and mercury have been found at concentrationsthat exceed regulatory MCL's or recommended maximim contaminantlevels (FMCL). Benzene has been recorded at levels up to 150 parts perbillion (ppb) and trichloroethene as high as 180 ppb. Concentrations of1,2-Dichloroethane have been as great as 51.0 ppb, and lead has been foundto 770 ppb. Mercury concentrations have been as much as 7.2 ppb. Waterfrom these wells is not withdrawn for human consumption; therefore, thereis no current public health threat associated with groundwater at thsselocations. However, recovered water is discharged to Army Creek wherethere may be exposure through contaminated fish consumption or recreationin contaminated surface water.EPA Region III, maintains that the AWC well field is hydraulicallyisolated from the aquifer contamination as a result of the groundwaterdivide created by the recovery well network, and AWC's adherence to itspermit conditions (withdrawal of up to 2 M3D). However, it is alsopossible that some 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 the Artesian Water Ccmfany wells has detected1,2-dichloroethane (maximim 11.0 ppm) in raw water at levels greater thanits MCL. long term consumption of this contaminated raw water could posea health threat; however, monitoring of the finished water distributedthrough the public water system did not show any contaminant levels aboveMCL or FMCL values.

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flR300l*97

Groundwater contamination migration 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 which should result in further groundwater improvement. Theseremedial 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 Army Creek Bightbe a problem because of arsenic which was detected at concentrationsranging to 13,540 ppb. Also, lead concentrations as high as 175,000 ppbwere recorded. The potential threat to human health should be diminishedconsiderably after the landfill cap is in place, the treatment systen forrecovered water being discharged to the creek is in operation, andcontaminated sediments have been remediated.

Although reference documents do not include data that specifically define ••contaminant concentrations in on-site soils and wastes; availableinformation regarding waste types, disposal practices, and constituentsthat have been released to groundwater indicate that contaminants arelikely to be in surface media at levels that pose a potential threat tothe health of intruders and unprotected remedial workers via dermalcontact and ingestion. Remedial workers also may be at risk of physicalinjury if appropriate safety procedures are not followed. later, with aproperly constructed and maintained cap in place, the threat to humanhealth from on-site soils should be minimal, if any. However, anyintruders might be exposed to gaseous contaminants emitted through capvents at concentrations that could pose a public health concern- or, formethane, a physical hazard because of its explosive characteristics.

Ihere are exposure issues for which the level of health concern cannot beevaluated because related contaminant information is not available orcannot be developed at this time. These include (1) construction of thecap may result in exposure to intruders to releases of methane or gaseouscontaminants through vents, and (2) fish possibly may bioconcentratecontaminants from their environment to levels that might pose a threat tothose who consume them.

OONCirniOlE AND RECOMMENDATIONS

A. (DNCUJSIONS

This site is may be 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. As noted in theHuman Exposure Pathways section above, human exposure to contaminants may

Page 7

be occurring, the public water supply which originates from groundwaterwithdrawn downgradient of the DSGL and ACL facilities could pose a publichealth threat if contaminants occur in finished water at unfavorableconcentrations. In addition, on-site trespassers may be exposed tocontaminants in soil and air which could potentially affect human health.Persons using the creek for recreational purposes may be exposed tocontaminants in sediment at concentrations that potentially affect health,and persons consuming contaminated fish from the creek also may beexposed. After the landfill is capped, intruders may be exposed tomethane and gaseous contaminants released through vents at levels that maypose a threat to safety and health.

B. RECCMMENDATIONS

1. In accordance with CERCLA as amended, the Army Creek Landfill NHLsite, New Castle County, Delaware has been evaluated for appropriatefollow-up with respect to health effects studies. Inasmuch as thereis no extant documentation or indication, in the information and datareviewed for this Health Assessment, that human exposure to on-site or.off-site contaminants is currently occurring and there are no tests toevaluate past exposures, this site is not being considered forfollow-up health studies at this time. However, if data becameavailable suggesting that human exposure to significant levels ofhazardous substances is currently occurring or has occurred in thepast, ATSDR will re-evaluate this site for any indicated follow-up.

2. ATSDR concurs with the FDD proposal to continue monitoring todetermine the effectiveness of the remedial action on groundwaterquality. Monitoring for finished water delivered to Artesian HaterCompany 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 theuse of institutional controls to prevent installation of water supplywells into contaminated portions of the aquifers until the groundwateris improved to drinking-water quality.

3. ihe proposed system for treating groundwater should be designed andoperated so that contaminants in the discharge to Army Creek are atlevels below those of public health concern. Itie system discharge,and surface water and sediments should be monitored for the durationof the treatment program in order to develop appropriate data on whichto evaluate any related health concern.

4. After the landfill cap is in place, periodic air monitoring should beconsidered to determine whether methane gas or gaseous contaminantreleased at vents pose hazard or public health concern.

5. Prevention of unauthorized entry onto the landfill should beconsidered to minimize the potential for exposure.

Page 8

6, 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.

7. Monitoring data or other information (e.g., wildlife consumptionsurvey) are needed in order to evaluate whether or not consuming fishfrom Army Creek poses a potential threat to health.

8. Remedial workers should adhere to applicable regulations andrecommendations outlined by the Occupational Safety and HealthAdministration and National Institute for Occupational Safety andHealth.

9. AOSDR concurs with the intended further evaluation of Army Creeksedirents. This evaluation can provide the necessary data in order toaddress the exposure issues mentioned in the Public HealthImplications Section.

PREPARERS OF REPORT

Reviewer: , Don GibeautEnvironmental Health EngineerEnvironmental Engineering Branch

Oiarlotta V. GavinClerk TypistEnvironmental Engineering Branch

Regional Representative: Nicholas J. DiNardoPublic Haalth AdvisorRegion IIIField Operations Branch

REFERENCES

1. Weston, 1986, Feasibility Study, Army Creek landfill

2. USEPA, 1986, Record of Decision, Army Creek landfill

3. Dunn Geoscience Corporation, 1987, Remedial Investigation, DelawareSand and Gravel Landfill

4. Dunn Geoscience Corporation, 1988, Feasibility Study, Delaware Sandand Gravel Landfill

5. USEPA, 198B, Record of Decision, Delaware Sand and Gravel Site

6. AOSDR Files

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AR300500

APPENDICES

Table l Off-Sice Contaminants of Potential ConcernTable 2 Human Exposure Pathways

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AR300501

TABLE 1

OFF-SITE CCNrAMDJANTS OF POTENTIAL CONCERN

GROUNPWATER (ppbl___________AND PUBLIC WATER INDUSTRIAL

RECOVERY WELLS fa) SUPPLV HEIIS (b)Ethyl Benzene ND - 690fylenes ND - 49.0 ND NDBenzene ND - 1500 ND • NDToluene ND - 8700 ND NDCj*./n_ -1.1 —— -i.»~-*i ••,——"~ «u - o/uu mBis (2-chloroethyl) ether ND ND ND

ND

*-*>-—— s-s? -^ S——-I- ————..-v.—IJ*yc_l!=J. HU

McJilotoethene ND - 140 ND ND1,2-Dichloroethane ND - 51.0 ND - 11.0

ND-37.3 ND-9.5 ND

JSiS »iu-° jg_ _ _ _ _ _ _ _ _ _ CREEK________

ODOTAMPPOTS SURFACE HATER (ppb) SEDIMENT fppb)Ethyl Benzene ND NDTotal Xylenes ND NDBenzene ND NDToluene ND NDBis(2-chloroethyl)ether ND NDTrichloroethene , ND ND1,2-Dichloroethane ND NDArsenic ND ND - 13,540Cadmium ND - 1.5 NDChroniuni ND - 17.6 ND - 25,540Lead ND - 7.7 ND - 175,000Mercury ND - 2.0 ND - 630

Sanpling conducted 1983, 1984, 1985, 1986No data for off-site soilsND - Not detecteda - Monitoring data from wells installed for the adjacent

Sand & Gravel NPL site and from some of the wells installedfor the Army Creek NPL site.

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

AR300502

TABLE 2

mm EXPOSURE PATHWAYS

MEDIA POTENTIAL EXPOSURE POINTS EXPOSURE ROUTES OP CONCERN [Y/N]E

ON-siTE * Intruders onto Y * Ingestion, denial contact.SOIL property possibly exposed.

Proposed capping measure shouldreduce potential for futureexposure.* Unprotected remedial workers Y * Ingestion, dermal contact.possibly exposed.

OFF-SITE * Persons at residences N * Not lively a significantand businesses probably are not environmental pathway/ no likelylocated near enough to be exposed exposure routes.to contaminants that may havemigrated front the site by air orrunoff. Proposed capping shouldreduce potential for releases tooff-site areas; and, with time,the potential for off-siteexposure should diminish.

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

routes (future water-supply wellinstallation unlikely).

OFF-SITE * Persons in the site Y * Ingestion, dermal contact, andvicinity use public water from also inhalation (volatilizedArtesian Water Company wells and groundwater contaminants duringpossibly may have been exposed to household use of groundwater).low concentrations ofcontaminants in the groundwater.With time, landfill capping,along with continued groundwaterwithdrawal and treatment, shouldreduce the potential forexposure,

Table Continued —

flf!300503

TABI£ 2(Continued)

MEDIA POTENTIAIi EXPOSURE POINIS EXPOSURE ROUTES OF CONCERN [Y/N]E

SURFACE ct>-srrg * No surface water bodies N * Not a current environmentalWATER, or sediment on-site, no current pathway, therefore, no exposureSEDIMENT exposure. routes.

OFF-SITE, * Persons using Army V * Ingestion, dermal contact,Creek for fishing or recreation inhalation.possibly would be exposed.Proposed capping measure shouldreduce contaminant releases tosurface water and sediment; and,over time, the potential forexposure should diminish. Ifremediation is accomplished forcreek sediments and recoveredgroundwater is treated prior todischarge, the subsequentpotential for exposure shouldminimized.

AIR pjj-srr * Intruders possibly are V * Inhalation, ingestionexposed to airborne contaminants (contaminants), Explosion,volatilized or entrained from the physical injury (methane).ground surface. Proposed cappingshould reduce the potential forexposure, unless elevatedconcentrations of gaseouscontaminants or methane areemitted through vents.* Unprotected remedial workers Y * Inhalation, ingestion.possibly may be exposed toparticipate and volatilecontaminants.OFF-SITE * Persons at residences N * Not a likely environmentaland businesses probably are not pathway, no likely exposurelocated near enough to the routes.facility to be exposed toairborne contaminants transportedfrom the landfill surface, norare they .likely (not near enough)to be exposed to gases releasedthrough cap vents or through thesubsurface. Proposed cappingshould reduce the potential forexposure.

Table Continued —

AR30G5Q1*

TABI£ 2(Continued)

MEDIA POTENTIAL EXPOSURE POINTS EXPOSURE ROUTES OF CONCERN [Y/N]E

FOOD ON-SITE * No litely exposure. N * Not a current environnentalCHAIN pathway, no exposure routes.

OFF-SITE * Fish fran the Army Y * Ingestlon of contaminated fishCreek might be contaminated by tissue. •site releases. Over time,proposed capping should reducethe potential for contaminantmigration. When remediation ofcreek sediirents is completed andthe recovered gromxJwater istreated before discharge, thesubsequent potential for exposureform ingestion of contaminatedfish, should become even less.

== ' •• ._'_'.__.'..._ "_..'..:_• — ••-—-.____. .j.j F^— — --__.-}—" — •"._.• •—••-•-"- —•-•• —a r;

NoteE: Y = Route(s) potentially a concernN = Route(s) not of concern

AR300505