SITE INFORMATION AND CORRESPONDENCE

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-w'.BLE 1 -CHECKLIST OF REQUIRED DATA — FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: California Stop, 2220(formerly 2224)Manthey Road, Stockton, San Joaquin County Y 1. Distance to production wells for municipal, domestic. Seven private water supply wells were identified within 2,000 feet agriculture, industry and other uses within 2000 feet of the site: of this Site. The closest well,about 370 feet northeast of the site, and five additional private wells are up-gradient of the Site. The Y seventh well is cross-gradient. These wells should not be threatened by the release from this Site. 2. Site maps, to scale, of area impacted showing locations of former Site maps were provided in reports showing location of tanks, monitoring wells and structures on-site. and existing tank systems, excavation contours and sample locations, Y borings and monitoring wells elevation contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities; 3. Figures depicting lithology(cross Cross-sections depicting lithology were provided in the 2010 Corrective Action Plan. Y section), treatment system diagrams, 4. Stockpiled sot!remaining on-site or San Joaquin County will require all investigative derived waste be removed from the Y site before closure of this case. off-site disposal(quantity): 5. Mite dip wells remainingon-Site, fate; San Joaquin County will require all wells be destroyed before closure of this case. Y 5. Tabulated results of all groundwater Tabulated results of groundwater elevation data is provided in groundwater monitoring reports. elevations and depths to water Y 7. Tabulated results of all sampling and analyses: Tabulated results cf groundwater data were provided in reports. One soil sample collected from a depth of 27 ft.bgs was analyzed for lead content and MDetection limits for confirmation sampling the result was 32 mg/kg. This values is believed to represent naturally Eloccurring lead in soils in this area. Lead analyses Y 8. Concentration contours of contaminants found and those remaining in soil Soil and groundwater concentration contours Feqgroundwater, and both on-site and off-site: depicting lateral and vertical delineation are Lateral and Y Vertical extent of soil contamination included in the 2010 CAP. Lateral and BVertical extent of groundwater contamination N 9. Zone of influence calculated and assumptions used for subsurface March an eight hour SVE pilot rest was conducted and the calculated radius of influence in remediation system and the zone of capture attained for the soil and shallow soil was 75 feet. groundwater remediation system; Y 10.Reports/information ❑Y Unauthorized Release Form M QMRs ❑Y Well and boring logs ❑N PAR ❑N FRP ❑Y Other Corrective Action Plan Y 11.Best Available Technology(BAT) used or an In June 2013,a six-month ozone pilot test was initiated. San Joaquin Co.received explanation for not using BAT; notification from the St. Bd. CUF that the case should be closed and the pilot test was terminated in October 2013. Y 12.Reasons whybackground walls unattainable San Joaquin Co.received notification from the St. Bd. CUF that the case should g be closed and the pilot test was terminated in October 2013. usin BAT: Y 13.Mass balance calculation of substance Calculated residual petroleum in soil about 6,147 lbs. (-1,000 gallons)and about 524 lbs. (-84 gallons)in groundwater. About 1.2 lbs. of petroleum was removed treated versus that remaining, during an eight hour SVE test. The exient of petroieum impacts are adequarely defined by 71 14.Assumptions. parameters, calculations and model used grab groundwater samples collected across Manthey Road to in risk assessments, and fate and transport modeling, the west of the site. .Rationale why conditions remaining at site will not Groundwater impacts are stable to decreasing in concentration in 15 Y monitoring wells on-site. No sensitive receptors appear to be adversely impact water quality, health, or other beneficial threatened and under current land use residual pollution will not uses,-and adversely impact human health or the environment. N No WET or TCLP analyses were requested. 16.WET or TCLP results By: Comments: The site is an active service station bounded to the east by Interstate Hwy. 5 and a large open field to the west. Residential homes are south of the site and a commercial property currently exists to the north. Although multiple water supply wells were identified within 2,000 feet of this site,the majority of the wells are up-gradient of the cic site and one well is located cross-gradient. This site does not meet the Low Threat Closure Policy criteria because MtBE concentrations in one on-site well are greater than 1,000 ug/L and a private well is located 370 feet away. In Date: June 2013, a six-month ozone pilot test was initiated. San Joaquin Co. received notification from the St. Bd. CUF that 10/28/2014 the case should be closed and the pilot test was terminated in October 2013. In general, pollutant concentrations are stable to decreasing and appear to be limited to the station property.