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Is BLE 1 - CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: ARCO Service Station, 7906 N. EI Dorado St., Stockton, San Joaquin County (RB #390102)
<br /> Y1 1. Distance to production wells for municipal, domestic, A 2004 sensitive receptor survey reported two water
<br /> agriculture, industry and other uses within 2000 feet of supply wells located within 2,000' of the Site. The nearest
<br /> the site. well is 1,200' to the southeast. None of the wells are
<br /> threatened by the release.
<br /> Y 2. Site maps, to scale, of area impacted showing locations In 11/861, one 550-gallon waste oil UST was removed. In
<br /> of any former and existing tank systems, excavation 8/93, two 4,000-gallon, one 6,000-gallon and one 10,000-
<br /> contours and sample locations, boring and monitoring gallon gasoline USTs were removed. Site maps and
<br /> well elevation contours, gradients, and nearby surface figures showing tank locations, excavations, building and
<br /> waters, buildings, streets, and subsurface utilities; I residual pollutants were provided in investigation reports.
<br /> Y 3. Figures depicting lithology (cross Site lithology consists of clay, silt, and sand to 100', the total depth investigated.
<br /> section), treatment system diagrams; An air sparge/soil vapor extraction treatment system was constructed on the
<br /> western (dispensers) andsouthern (USTs) portions of the property.
<br /> Y1 4. Stockpiled soil remaining on-site Approximately 920 y of excavated soil was removed and transported to BFI
<br /> or off-site disposal (quantity); landfill in Livermore. Mass estimate for excavated soil was not reported by the
<br /> consultant.
<br /> Y 5. Monitoring wells remaining on-site, Twenty (20) monitoring wells (MW-1 through MW-7, MW-11 through MW-23) and
<br /> ate; eighteen (18) remediation wells (MS-1 through MS-3. AS-1 through AS-3, VW-1
<br /> through VW42) will be properly destroyed prior to closure.
<br /> 6. Tabulated results of all groundwater Tabulated data was provided in reports indicating depth to groundwater from
<br /> elevations and depths to water; 34' bgs to 66' bgs. Groundwater flow direction from southeast to northeast.
<br /> Groundwater gradient varied from 0.002 ft/ft to 0.005 Wit.
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports, including waste oil analyses.
<br /> and analyses:
<br /> Y❑ Detection limits for
<br /> confirmation sampling
<br /> �Y Lead analyses
<br /> 8. Concentration contours of contaminants found and those remaining in The horizontal and vertical extent of the
<br /> soil and groundwater, and both on-site and off-site: petroleum pollution is confined to the
<br /> property limits.
<br /> FYILateraland FYIVerticalextent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> Y 9. Zone of influence calculated and assumptions used for subsurface An air sparge/soil vapor extraction treatment
<br /> remediation system and the zone of capture attained for the soil and system was constructed with a designed 70'
<br /> groundwater remediation system; radius of influence.
<br /> 10. Reports / information FY Unauthorized Release Form FY QMRs (89) 1-92 to 9-12
<br /> ❑Y Welland boring logs PAR ❑Y FRP ❑Y Other No Further Action Report, 4-13
<br /> Y 11. Best Available Technology (BAT) used or Leak was stopped by removing tank and piping, over-excavation
<br /> an explanation for not using BAT,- removed additional soil pollution. SVE/AS was chosen as the BAT and
<br /> operated from 1995 to 2009.
<br /> Y 12. Reasons why background was/is not Soil pollution presents a minimal threat to human health and
<br /> finable using BAT; groundwater pollution is predicted to be restored in 71 years.
<br /> Y1 13. Mass balance calculation of substance Consultant stated initial mass was 10, 782 lbs. (1, 634 gal.). SIZE removed
<br /> treated versus that remaining; 9, 100 lbs. (1,379 gal.) of TPH from soil. Estimated residual TPH mass is
<br /> 1, 673 lbs. (253 al.) in soil and 321b. (5 al.) in groundwater.
<br /> Y 14. Assumptions, parameters, calculations Site meets the criteria in the LTCP for commercial use (active service
<br /> and model used in risk assessments, and fate station). Consultant states site does not represent a significant
<br /> and transport modeling; environmental or health risk.
<br /> Y1 15. Rationale why conditions remaining at Soil and groundwater pollution is reportedly confined to the property
<br /> site will not adversely impact water quality, limits. Land use (commercial) is not expected to change in the
<br /> health, or other beneficial uses; and foreseeable future. WQGs will be reached by 2084. Groundwater plume
<br /> is stable and slowly decreasing in concentration.
<br /> By: JLB Comments: Multiple USTs were removed at the subject site. Based on the stable and declining
<br /> concentrations in groundwater, no foreseeable changes in future land use (commercial), and no risks from
<br /> Date: soil vapor and soil, Regional Board staff concur with San Joaquin County's Closure Recommendation.
<br /> 118/29/2013
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