SITE INFORMATION AND CORRESPONDENCE_FILE 2

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`ft� S"aw, TABLE 1 -CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Valley Motors, 800 E. Main St., Stockton, San Joaquin County(RB#390546) Y 1. Distance to production wells for municipal, domestic, A 2012 sensitive receptor survey reported 4 water supply agriculture, industry and other uses within 2000 feet of wells located within 2,000'of the Site. The nearest wells the site. are 900'to the west and 1,300'to the west. None of the wells are threatened by the release. Y 2.Site maps, to scale, of area impacted showing locations In 10/90, two 5,000-gallon gasoline USTs were removed. of any former and existing tank systems, excavation Site maps and figures showing tank locations, contours and sample locations, boring and monitoring excavations,building and residual pollutants were well elevation contours, gradients,and nearby surface provided in investigation reports. waters, buildings,streets, and subsurface utilities; Y 3. Figures depicting lithology(crossSite lithology consists of clay,silt,and sand to 73, the total depth investigated. section), treatment system diagrams; Due to low concentrations in groundwater,a treatment system was not required Dy the regulatory agency. Y 4. Stockpiled soil remaining on-site The fate of excavated soil were not reported. Mass estimates for excavated soil or off-site disposal uanti were not reported by the consultant. 45.Monitoring wells remaining on-site, Ten(10)monitoring wells(SW-1 and VM-1 through VM-9)and one remediation e; well(VT--1)will be properly destroyed prior to closure. YJ 6. Tabulated results of all groundwater Tabulated data was provided in reports indicating depth to groundwater from elevations and depths to water; 28'bgs to 44'bgs. Groundwater flow direction towards the east. Groundwater gradient varied from 0.0005 ft/ft to 0.001 ft/ft. 7. Tabulated results of all sampling All data adequately tabularized in various reports. and analyses: Y❑ Detection limits for confirmation sampling Lead analyses QY 8. Concentration contours of contaminants found and those remaining in The horizontal and vertical extent of the soil and groundwater, and both on-site and off-site: petroleum pollution is confined to the property limits. FALateral and �Vertical extent of soil contamination FYI Lateral and FY Vertical extent of groundwater contamination 9.Zone of influence calculated and assumptions used for subsurface A treatment system was not constructed due remediation system and the zone of capture attained for the soil and to declining concentrations. groundwater remediation system; 10.Reports/information QY Unauthorized Release Form ❑Y QMRs(45) 7-96 to 12-13 ❑Y Well and boring logs 151 PAR I Y1 FRP ❑N Other YJ 11.Best Available Technology(BAT)used or Leak was stopped by removing tank and piping. SVE pilot study an explanation for not using BAT; removed-70 gallons, followed by natural degradation due to low concentrations in groundwater. Unable Reasons why background was/is not Soil pollution presents a minimal threat to human health and UUnable usin BAT; -groundwater pollution is predicted to be restored in 10 years. Y__1 13.Mass balance calculation of substance Initial mass estimates were not provided. SVE pilot study removed 427 treated versus that remaining; lbs. (70 gal.).Estimated residual TPH mass is 0 Ib. (<O.17 gal.)in groundwater. Y 14. Assumptions, parameters, calculations Site meets the criteria in the LTCP for commercial and residential use. 7 and model used in risk assessments, and fate Consultant states site does not represent a significant environmental or and transport modeling; health risk. Y 15. Rationale why conditions remaining at Soil and groundwater pollution is reportedly confined to the property site will not adversely impact water quality, limits.Land use(commercial)is not expected to change in the health, or other beneficial uses;and foreseeable future. WQOs will be reached by 2023. Groundwater plume is stable and slowly decreasing in concentration. By: JLB Comments:Multiple USTs were removed at the subject site.Based on the stable and declining concentrations in groundwater, no foreseeable changes in future land use(commercial), and no risks from Date: groundwater, soil vapor, and soil, Regional Board staff recommend closure of petroleum pollution under the 1/27/2014 State Water Resources Control Board Low Threat Closure Policy. Remaining solvent impacts will be addressed by Site Cleanup Program.