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► - WbLE 1 -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Woolsey Oil Cardlock Station, 1501 W. Charter Way, Stockton San Joaquin County(RB#391036)
<br /> Y 1. Distance to production wells for municipal, domestic, A 2009 sensitive receptor survey stated ten wells are
<br /> agriculture, industry and other uses within 2000 feet of the site. located within 2,000'of the Site, with the closest active
<br /> wells 1000'NE, 1250'SW, and 1250'ENE
<br /> Y 12. Site maps, to scale, of area impacted showing locations of In January 1999, two 4,000-gallon gasoline and one
<br /> any former and existing tank systems, excavation contours and 4,000-gallon diesel USTs were removed from the site.
<br /> sample locations, boring and monitoring well elevation One 350-gallon waste oil UST was removed in July 1999.
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets, and subsurface utilities;
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site litho/ogy consists of clay,silt,and sand to 30', the
<br /> diagrams; total depth investigated.
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Approximately 414 cubic yards of soil was—over-
<br /> excavated and transported to Forward Landfill in
<br /> Manteca.
<br /> Y 5. Monitoring wells remaining on-site, fate; I Five monitoring wells(MW-1 through MW-5) will be properly abandoned.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 11'to 17'bgs. Groundwater flow
<br /> elevations and depths to water; direction varied from northeast to west. Groundwater gradient varied
<br /> from 0.001 ft/ft to 0.027 ft/ft.
<br /> 7. Tabulated results o a 1 same mgAll ata a equate y abuTar►ze m various reports;including closure report.
<br /> and analyses:
<br /> Y❑ Detection limits for confirmation
<br /> sampling
<br /> �Y Lead analyses
<br /> 8. Concentration contours of contaminants found and those remaining in soil and The extent of the identified
<br /> groundwater, and both on-site and off-site: contamination is shown in applicable
<br /> FLYfli
<br /> reports.
<br /> Lateral and Y❑Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Over-excavation of soil was the
<br /> system and the zone of capture attained for the soil and groundwater remediation engineered remediation.
<br /> system;
<br /> 10.Reports/information QY Unauthorized Release Form ❑Y QMRs 38 from 11/99 to 10/09
<br /> FY Welland boring logs ❑Y PAR [N-1FRPFYI Other Site Conceptual Model(1-09), Soil Vapor
<br /> Investigation 8-09 and Closure Report 11/09
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not USTs removal, over-excavation, and natural
<br /> using BAT,' I attenuation.
<br /> UY 12. Reasons why background was/is Minor residual soil and groundwater contamination remain on-site.
<br /> ttainable using BAT,'
<br /> Y713.Mass-balance calculation-of substance treated_ The consultant did not estimate mass removed by over-excavation of
<br /> 7
<br /> versus that remaining; soil,buf did estimate 1 J pounds of-TPHg and 400 pounds of TPHd"
<br /> remain in soil, and less than 2 pounds of TPH remain in groundwater.
<br /> Y 14. Assumptions,parameters, calculations and The consultant stated TPHg and benzene soil vapor samples did
<br /> model used in risk assessments, and fate and exceed ESLs. A Tier 2 J&E Model showed benzene as a 6.1E-7 cancer
<br /> transport modeling; risk and<0.2 hazard quotient, and TPHg as a 5.4E-2 hazard quotient;all
<br /> are values which do not pose an unacceptable human health risk from
<br /> vapor intrusion.
<br /> Y 15. Rationale why conditions remaining at site Soil and groundwater contamination reportedly are limited in extent.
<br /> will not adversely impact water quality, health, or Land use(commercial)is not expected to change in the foreseeable
<br /> other beneficial uses;and future. WQGs will be reached in 15 years.
<br /> By: JLB . Comments:In January 1999, two 4,000-gallon gasoline and one 4,000-gallon diesel USTs were removed from
<br /> the site. One 350-gallon waste oil UST was removed in July 1999. Based upon 38 quarters of groundwater
<br /> Date: monitoring showing a stable plume with declining concentrations, the limited extent of contamination
<br /> 4/8/2010 remaining in soil and groundwater, fate and transport modeling showing the residual groundwater plume will
<br /> not leave the property boundary, no foreseeable changes in land use,and minimal threats from soil vapor
<br /> intrusion, Regional Board staff concur with San Joaquin County's Closure Recommendation.
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