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LE 1 -CHECKLIST OF REQUIRED DATA FOR NO FURTRM ACTION REQUESTS AT UNDERGROUND 4K SITES Site Name and Location: Pacific Mini Mart,4511 Pacific Avenue, Stockton,San Joaquin County(Case 390570) Y I Distance to production wells for municipal, domestic, A well survey, including a field reconnaissance,identified 15 culture, industry and other uses within 2000 feet of the site. wells within 2,000 feet The nearest is 250 west (crossgradient)of the site. Based upon sampling data,no wells are threatened due to this case. Y 2. Site maps, to scale, of area impacted showing locations Contained in several reports on file. of any former and existing tank systems, excavation contours and sample locations, boring and monitoring well elevation contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities; Y1 3. Figures depicting lithology(cross section), treatment Site lithology consists of sandy silt to 35 feet,gravels to 40 system diagrams; feet, and clay generally underlain with sandy gravel to 60 feet. Treatment system diagrams in reports. N 4. Stockpiled soil remaining on-site or off-site disposal(quantity); 638 tons of impacted soil excavated and transported to Forward Landfill. Y 5. Monitoring wells remaining on-site, fate; A reported 26 monitoring wells installed over time. All monitoring wells will be property abandoned prior to formal closure per County. 6. Tabulated results of all groundwater Depth to groundwater varied from—25 feet to--55 feet below ground elevations and depths to water, surface(bgs). The groundwater gradient varied from 0.004 to 0.02. The downgradient groundwater flow direction has been to the northeast. 7. Tabulated results of all sampling All data adequately tabularized in various reports, including closure report. and analyses: Detection limits for confinnation sampling Lead analyses 8. Concentration contours of contaminants found and those remaining in soil and The extent of the identified groundwater, and both on-site and off-site: contamination shown in applicable reports. 0 Lateral and Y❑Vertical extent of soil contamination Lateral and Vertical extent of groundwatercontamination 9. Zone of influence calculated and assumptions used for subsurface remediation Groundwater pump and treat and system and the zone of capture attained for the soil and groundwater remediation soil vapor extraction. system; 10.Reports/inforination FY] Unauthorized Release Form FYI QMRs(from 1993 to 2009) FY] Well and boring logs [Z PAR FRP n Other'Case Closure Report Yj 11.Best Available Technology(BAT) used or an explanation for not using BAT, Removal of USTs and natural attenuation. Y 12. Reasons why background wasris unattainable using BAT; Limited soil contamination remains on-site. Y1 13.Mass balance calculation of substance treated versus that The consultant estimates 0.15 lb's of TPHg remains in remaining; groundwater and 44.66 tbs. in soil. �, 14. Assumptions, parameters, calculations and model used in Due to depth of residual soil, and active SVE on-site, no risk assessments, and fate and transport modeling; additional vapor sampling conducted. Y 1 15. Rationale why conditions remaining at site will not adversely Groundwater concentrations continue to decline with impact water quality, health, or other beneficial uses;and many wells already at non-detect. Site no longer poses a threat. By: JIM —Comments:Due to groundwater and soil remedial efforts, confirmation sampling has shown that this site no longer poses a threat to human health and safety or to water quality. Regional Board staff concurs with San Date: Joaquin County's recommendation for issuance of a No Further Action letter. 7128109