SITE INFORMATION AND CORRESPONDENCE CASE 1

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+ - 'FABLE 1 -CHECKLIST OF REQUIRED DATA �..f FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Former Western Lift,,Case#1,3430 S. EI Dorado St.,Stockton, San Joaquin County(RB#390639) :YD 1. Distance to production wells for municipal, domestic, A 2003 sensitive receptor survey reported no water agriculture,industry and other uses within 2000 feet of the site. supply wells within 2,000'of the site. Y 2. Site maps,to scale,of area impacted showing locations of any In 6/91, two 1,000-gallon gasoline and one 2,000- former and existing tank systems, excavation contours and gallon diesel USTs were removed. Site maps and sample locations,boring and monitoring well elevation figures showing tank locations, excavations, contours,gradients,and nearby surface waters,buildings, building and residual pollutants were provided in streets,and subsurface utilities; investigation reports. Y1 3.Figures depicting lithology(cross Site lithology consists of clay,silt,and sand to 54', the total depth investigated. section), treatment system diagrams; Y 4.Stockpiled soil remaining on-site Approximately 2,250 ycr of over-excavated soil was reportedly disposed at an or off-site disposal(quantity); unnamed Class 11 landfill. TJ 5.Monitoring wells remaining on-site, Two(2)remaining Case 1 monitoring wells(MW-1 and MW-4)will be properly destroyed prior to closure. 6. Tabulated results of all groundwater Depth to groundwater varied from 22'bgs to 42'bgs. Groundwater now elevations and depths to water; direction was towards the northeast. Groundwater gradient varied from 0.001 ft/ft to 0.002 ft/ft. 7. Tabulated results of all sampling All data adequately tabularized in various reports. and analyses: FYIDetection limits for confirmation sampling �Y Lead analyses 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 contamination are confined to the property limits. El Lateral and _ Vertical extent of soil contamination Lateral and ry Vertical extent of groundwater contamination 9.Zone of influence calculated and assumptions used for subsurface An engineered remediation was not remediation system and the zone of capture attained for the soil and required by the regulatory agency. groundwater remediation system; 10.Reports/information[0 Unauthorized Release Form ❑Y QMRs(45)6-92 to 1-09 Well and boring logs PAR ❑N FRP FY] Other Site Conceptual Model&Closure Summary Re ort,4-09 Y 111.Best Available Technology(BAT)used or an USTs removal, over-excavation,and natural attenuation. explanation for not using BAT; Y 12. Reasons why background was/is not Soil contamination does not present a threat to human health and finable using BAT; groundwater pollution is predicted to be restored in two years. Y 13.Mass balance calculation of substance Consultant estimated 3,664 lbs. of TPH was removed by over- treated versus that remaining; excavation,and estimated residual TPH mass as 0.015 lbs. in soil and 0.003 lbs. of TPH in groundwater. 7Y 14. Assumptions,parameters, calculations Site passed LTCP and Region 2 ESLs. Consultant states site does not and model used in risk assessments,and fate represent a significant environmental or health risk. USTCUF has and transport modeling; recommended site for closure. 7Y 15. Rationale why conditions remaining at Soil and groundwater contamination reportedly are confined to the site will not adversely impact water quality, property boundaries.Land use(commercial)is not expected to change health, or other beneficial uses;and in the foreseeable future. WQGs will be reached by 2015. Groundwater plume is stable and decreasing in concentration. By. JLB Comments:In 6/91, two 1,000-gallon gasoline and one 2,000-gallon diesel UST were removed at the subject site.Based on the stable and declining concentration s in groundwater,no foreseeable changes in future Date: land use(commercial),and no risks from-soil vapor and soil,Regional Board staff concur with San Joaquin 7/16/2013 County's Closure Recommendation.