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� r`'-4BLE 1 -CHEGKLiST C1F REQUIRED DATAQ �
<br /> FOR NO FURa..,,R ACTION REQUESTS AT UNDERGROUND UNK SITES
<br /> Site Name and Location: City of LathroplDalwinder Dhoot,15688 Harlan Rd.,Lathrop,San Joaquin County(Case 391176)
<br /> Y IDistance to production wells for municipal, domestic; According to Geotracker,there are no active public wells
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<br /> culture; industry and other uses within 2000 feet of the site: within%mile of site. Oakwood Lake WaterDistrict
<br /> Subdivision provides public water to the area.
<br /> 2. Site maps,to scale,of area impacted showing locations Two 500-gallon unknown contents USTs and associated
<br />! of any former and existing tank systems, excavation piping were removed from the site,located on the property
<br /> contours and sample locations,boring and monito"ring well border of the City street and the new Best Western motel, j
<br /> elevation contours,gradients, and nearby surfacer waters during construction in 4107. The tanks-were abandonedin
<br /> buiJdin s streets and subsurface utilities; ince at a former WJ ins Market in me 1960's:
<br /> Y 3. Figures depicting lithology(crass section) treatment Site lithology consists of clay,silt,and sand to
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<br /> system diagrams; 15 feet,the total depth investigated. '
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<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Approximately 45 cu.yds. of contaminated soil was
<br /> removed and transported to Forward Landfill in
<br /> Manteca.
<br /> Three monitoring wells(M W-1 through;MW-,3)remaining on-site will be f
<br /> Y 5. Monitoring wells remaining on-site; fate; propertyabandoned.
<br /> 6. Tabulated results of all groundwater Depth to,groundwater varied from 11 to 12 feet below ground surface(bgs).
<br /> elevations and depths to water, Thetgroundwater gradient varied from 0.004 to 0.005. The downgradlent
<br /> groundwater flow direction was towards the northwest. .-
<br /> y=T,-•-Tabulated•results-oaf-all-sampling -Maximum-confirma#ion:soil concentration-{4ItfT)-was-T.PHd,21-mg&g.-4 n-41{18,-soil--•
<br /> and analysos: boring after results were all ND. Maximum grab groundwater concentrations
<br /> during over-excavation(5/07)were TPHg, 7,900 ug1L;TPHd, 16,000 ugIL benzene;
<br /> Detection.limits forconfimtation 140 ug1L;1toluene,33 ug/L;ethylbenzene,33 ug1L ;andxylenes,200 ugIL. In 12/08,
<br /> I the maximum groundwater monitoring result was TPHd,74 uglL.
<br /> sampling
<br /> QY Lead analyses
<br /> 8. Concentration contours of contaminants found and those remaining in soil and The extent of the idetred ,
<br /> j groundwater, and both on-site and gaff-site: contamination is shown in -,
<br /> applicable reports.
<br /> Lateral and L1/'vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwatercontamina tion
<br /> 9.• Zone of influence calculated and assumptions used forsubsurface remediation An engineered remediation was
<br /> system and the.zone:of capture attainted for'the sail and groundwater remediation: not required by:the.regulatory
<br /> system; agency,
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<br /> 10.Deports 1information U Unauthorized Release Form G?.! QMRs`(3 from 44/08 to 12108) i
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<br /> Well-and bonng::logs PAR FRP Other;
<br /> Y 11.Best Available Technology(BAT)used or an eXplanatian for not using BAT; Removal of USTs,over-excavation,And
<br /> !I natural attenuation.
<br /> 12. Reasons why background wasfs unattainable;)usin BAT Limited soft contamination remains on-site.
<br /> r The consultant did not estimate contaminatronrenraining
<br /> 13.Mass balance calculation of substance treated'Versus that
<br /> remaining; In soil or groundwater.
<br /> - 14:=Assumpptionsy aiatneters>-ealsulations-and-m6det-used-inm«_No.Region.2.ESLs_wereexceeded for�sorl_samptes-Site 4 ...
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<br /> nsk-assessments,and,fate and transport modeling; is a City s#reetlsidewalkl►andscape;and larrtd use
<br /> {commercial)is not expected to change:h tha:
<br /> foreseeable future.
<br /> Y:5 15; Rationale:why:conditions remaining at site wrlflnot adversely Sol/and groundwater contamination are limltent l0 extent
<br /> impact water+Tualtty,..hea1#h;..oro1her beneficial uses;and Results of 3 quarters of groundwater monftring:show a
<br /> decreasln trend in concentrations.
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<br /> JAR Comments Two 500-gallon USTs and associated piping were removed from subject site,,located on the
<br /> property border.of the city streets nal.the new Best Western motel,during construction in 4107.The tanks were
<br /> Date. abandoned in pieat
<br /> ce .a forrrter Wiggans Market in the 1960's. Maximum confirmation soli+concentration{4100
<br /> 312512009: wes 7'PHd,21;nrglkg. In4104;.soil boiling after results were all ND. Maximum grab grounrdwaterconcentratiorrs
<br /> during over excavation(&07)were T,P,Ng, 7,900 ug/L;TPHd 10,000 ug& benzene,f40.ug1L,foluene,..IuglL;
<br /> etllylbenzene,341 ug/L.;and xylenes, 200 ug1L. in 12(08, the maxftum groundwater monitoring resin#Was
<br /> TPHd,,74:0glL. Based upon 3;quartsh of declining groundwater concentrations,:no reported threat from vapor ;
<br /> lrrtruslon,no anticipated threat to sensitive receptors,no anticipated changes to.land use(commercial),and t
<br /> *9 limited+sx nt of contamination plesent In soil and groundwater,Re4�ional:l3oard stili°concur with ySan
<br /> Jrlecicrincounty's closure Recommendation.
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