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TABLE 1 -CHECKLIST OF REQUIRED*bATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Waterloo Shell,4315 Waterloo Rd., Stockton, San Joaquin County(RB#390512)
<br /> :71 1. Distance to production wells for municipal,domestic, A 2001 sensitive receptor survey reported 6 domestic,2
<br /> agriculture,industry and other uses within 2000 feet of irrigation, 1 industrial,2 unknown use and 1 municipal
<br /> the site. water supply wells located within 2,000'of the Site. The
<br /> nearest well is 1,150'northeast.None of the wells are
<br /> threatened by the release.
<br /> Y1 2. Site maps, to scale, of area impacted showing locations In 12/86, one 550 gallon waste oil UST was removed.In
<br /> of any former and existing tank systems, excavation 12/94, two 5,000-gallon, one 7,000-gallon,and one 8,000-
<br /> contours and sample locations,boring and monitoring gallon gasoline USTs were removed.In 3/05, two 15,000-
<br /> well elevation contours,gradients,and nearby surface gallon gasoline USTs were removed. Site maps and figures
<br /> waters,buildings,streets,and subsurface utilities; showing tank locations, excavations, building and residual
<br /> pollutants were provided in investigation reports.
<br /> Y1 3.Figures depicting litholo Site lithology consists of clay,silt,and sand to 96, the total depth
<br /> g p g gy(cross investigated, p
<br /> section), treatments stem diagrams;
<br /> Y 4. Stockpiled soil remaining on-site or off- Approximately 700 y of excavated soil was removed and transported to
<br /> site disposal(quantity); BFI Landfill in Pittsburg.Approximately 500 yd'of excavated soil was
<br /> removed and transported to Forward Landfill in Manteca.Mass estimates
<br /> for excavated soil were not reported by the consultant.
<br /> Y 5.Monitoring wells remaining on-site,fate, Ten(10}monitoring-wells(MW-1 through MW-10)will be properly _
<br /> destroyed prior to closure.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 49'bgs to 75'bgs. Groundwater flow
<br /> elevations and depths to water; direction varied from north to northeast. Groundwater gradient varied from
<br /> 0.001 ft/ft to 0.02 ft/ft.
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports. Waste oil analytes were
<br /> and analyses: evaluated using groundwater samples since soil samples were not collected at the
<br /> ❑Y time of tank removal. Results indicate no detectable impacts from waste oil to
<br /> Detection limits for groundwater.
<br /> confirmation sampling
<br /> 0 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 extends less than 100'
<br /> offsite;however,groundwater
<br /> X Lateral and Vertical extent of soil contamination concentrations are declining in the only
<br /> Lateral and Vertical extent of roundwater contamination impacted offsite well,MW-10.
<br /> 9.Zone of influence calculated and assumptions used for subsurface The regulatory agency did not require active
<br /> remediation system and the zone of capture attained for the soil and remediation.
<br /> groundwater remediation system;
<br /> 10.Reports/informationFY] Unauthorized Release FormFY] QMRs(51) 10-99 to 5-13
<br /> ❑y Well and boring logs❑y PAR ❑N FRP FY] Other Site Conceptual Model, 9-12
<br /> Y I 11.Best Available Technology(BAT)used or Leak was stopped by removing tanks and piping, over-excavation
<br /> an explanation for not using-BA T,' removed additional soil pollution_.Use-of additional cleanuptechnology
<br /> was not attempted.Natural processes are predicted to restore water
<br /> quality,
<br /> Y 12. Reasons why background was/is not Soil pollution presents a minimal threat to human health and
<br /> finable using BAT; roundwater pollution is predicted to be restored in 85 years.
<br /> Y 13.Mass balance calculation of substance Consultant estimated residual TPH mass as 1.67lbs. (0.25 gallons)in
<br /> treated versus that remaining; soil and 702.74 lbs. (106.47 gallons)in groundwater. No estimate
<br /> reported for mass removed by over-excavation.
<br /> 7Y 14. Assumptions,parameters, calculations Site meets the LTCP criteria for commercial use(active service station).
<br /> and model used in risk assessments,and fate Consultant states site does not represent a significant environmental or
<br /> and transport modeling; health risk under current use.
<br /> I, 15. Rationale why conditions remaining at Soil and groundwater pollution is reportedly limited in extent.Land use
<br /> site will not adversely impact water quality, (commercial)is not expected to change in the foreseeable future. WQGs
<br /> health, or other beneficial uses;and will be reached by 2098. Groundwater plume is stable and slowly
<br /> 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 /> 3/26/2014
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