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<br /> -* %IriBLE 1 -CHECKLIST OF REQUIRED DATA Q
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: ZE Auto Repair/Former UltraMar Inc.SS 913792, 2255 S.Airport Wy.,Stockton,
<br /> San Joaquin County(R8#391129)
<br /> y 1. Distance to production wells for municipal, domestic, A 2013 sensitive receptor survey reported two water
<br /> agriculture, industry and other uses within 2000 feet of the supply wells(680'north & 1,750'south) within 2,000'of
<br /> the site.None of the wells are threatened by the release.
<br /> site. -
<br /> m s to scale of area impacted showing locations of .Prior to 1984,an unknown number, size,and contents
<br /> Y 2. Site maps, , p g
<br /> any former and existing tank systems,excavation contours USTs were removed. No records exist. Contaminated
<br /> and sample locations,boring and monitoring well elevation soil discovered during a site assessment in July 2002.
<br /> contours,gradients, and nearby surface waters, buildings,
<br /> streets,and subsurface utilities•
<br /> Y 13. Figures depicting lithology(cross Site lithology consists of clay,silt,and sand to 153', the total depth investigated.
<br /> section), treatment system diagrams;
<br /> Y 4.Stockpiled soil remaining on-site Approximately 1.65 tons of excavated soil was transported to Forward Landfill
<br /> or off-site dis oral uanti in Manteca.
<br /> Y 5. Monitoring wells remaining on-site, Twelve{12)monitoring and remediation wells(MW-2 through MW-i4)and seven
<br /> ate; (7)remedlation wells(VW-1 through VW-5,SW-1 and SW-2)will be properly
<br /> 7a te;
<br /> destroyed priorto closure.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 30'bgs to 47'bgs. Groundwater flow
<br /> elevations and depths to water; direction varied from northeast to southeast. Groundwater gradient was
<br /> 0.001 ft/ft.
<br /> sLyJ 7. Tabulated results of all sampling All data adequately tabularized in various reports.
<br /> and analyses:
<br /> RDetection limits for
<br /> confirmation sampling
<br /> Lead analyses
<br /> 8. Concentration contours of contaminants found and those remaining in The extent of the identified contamination
<br /> soil and groundwater,and both on-site and off-site: is described in the available reports.
<br /> Lateral and 0 Vertical extent of soil contamination
<br /> Lateral and MY Vertical extent of groundwater contamination
<br /> 9.Zone of influence calculated and assumptions used for subsurface The engineered remediation was over-
<br /> remediation system and the zone of capture attained for the soil and excavation and soil vapor extraction(SVE)
<br /> groundwater remediation system; I with airs ar in (AS).
<br /> 10.Reports/information[5] Unauthorized Release Form [Y QMRs(30)7-03 to 12-12
<br /> Well and boring logs PAR I
<br /> Y g g y y FRP y Other No Further Action Report, 5/13
<br /> YJ 11,Best Available Technology(BAT)used or an . Over-excavation,S VE/AS, and natural attenuation.
<br /> ex lanation.for not using BAT; ,
<br /> UY 12. Reasons why background was/is Residual soil and groundwater contamination remains.
<br /> ttainable using BAT I
<br /> Y 13.Mass balance calculation of substance' Consultant estimated initial TPH mass as 7,502.2 lbs in soil and 266.3
<br /> treated versus that remaining, lbs.in groundwater.However, SVE/AS removed 40,300 lbs TPH.
<br /> Approximately 10.2 lbs TPH remain in groundwater.
<br /> Y 14. Assumptions,parameters, calculations Site is an auto repair shop that passed LTCP and Region 2 ESLs for soil
<br /> and model used in risk assessments, and fate vapor. Consultant states site does not represent a significant risk.
<br /> and transport modelin ,
<br /> Y 1 15. Rationale why conditions remaining at Soil and groundwater contamination reportedly are limited in extent.
<br /> site will not adversely impact water quality, Land use(commercial)is not expected to change in the foreseeable
<br /> health,or other beneficial uses;and future. Consultant estimated time to reach WQGs as 2049. Groundwater
<br /> plume is stable and declining.
<br /> By: JLB Comments.Prior to 1984,an unknown number,size,and contents USTs were removed, and no records exist
<br /> at the subject site_ Contaminated soil discovered during a site assessment in July 2002.Residual soil and
<br /> Date: groundwater contamination remains.Based upon the limited extent of contamination reported in soil and
<br /> 5/29/2013 groundwater,a stable and declining concentration plume, no foreseeable changes in future land use
<br /> (commercial), and minimal risks from groundwater,soil vapor and soil,Regional Board staff concur with San
<br /> Joa uin Count
<br /> 's Closure Recommendation.
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