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v TABLE 1 -CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Dopaco Inc. Case 1 Toluene UST, 800 W. Church St., Stockton, San Joaquin County(RB#391187) Y 1. Distance to production wells for municipal, A 2012 sensitive receptor survey reported five(5)industrial water domestic, agriculture, industry and other uses supply wells located within 2,000'of the Site. The water supply within 2000 feet of the site. wells were properly destroyed in 11/14. Y 2. Site maps, to scale, of area impacted showing In 9/86, one 4,000-gallon Toluene tank was removed. Site maps and locations of any former and existing tank figures showing tank location, excavations, former building and systems, excavation contours and sample residual pollutants were provided in investigation reports. locations, boring and monitoring well elevation contours,gradients, and nearby surface waters, buildings,streets,and subsurface utilities; Y 3. Figures depicting lithology(cross Site lithology consists of clay,silt,and sand to 78, the total depth investigated. section), treatment system diagrams; Remediation consisting of soil over-excavation to 30'bgs was completed in 2/14. Y 4. Stockpiled soil remaining on-site or Approximately 300 cubic yards of excavated soil was removed and transported off-site disposal(quantity); to Potero Hills Landfill in Suisun City.Mass estimate for excavated soil was 9.2 lbs. 1.5 al. toluene removed. Y 5.Monitoring wells remaining on-site, All monitoring wells(DMW-1,DMW-3, DMW-4, DMW-5A,DMW-6A, DMW-5B,and ate; DMW-6B) will be transferred to the investigation of seven(7)additional USTs under Case 3 for this Site address. YJ 6. Tabulated results of all groundwater Tabulated data was provided in reports indicating depth to groundwater varied elevations and depths to water; from 12'bgs to 17'bgs. Groundwater flow direction was towards the northwest. Groundwater gradient varied from 0.0018 ft/ft to 0.0048 ft/ft. LYJ 7. Tabulated results of all sampling All data was tabulated in various reports.Lead sampling was conducted as part of and analyses: the removal action, Title 22 metals analysis. 0 Detection limits for confirmation sampling QY 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: toluene pollution is confined to the property limits. Lateral and FY extent of soil contamination Lateral and Vertical extent of groundwater contamination 9.Zone of influence calculated and assumptions used for subsurface Zone of influence and capture were not remediation system and the zone of capture attained for the soil and applicable to the remedial action. groundwater remediation system; 10.Reports/information QY Unauthorized Release FormFY] QMRS(7) 12-12 to 12/14 Well and boring logsFY] PAR 0 FRP a Other Closure Report, 1/15 Y 111.Best Available Technology(BAT)used or Leak was stopped by removing tanks and piping. BAT was over- an explanation for not using BAT; excavation. ZY 12. Reasons why background was/is not Residual soil pollution presents a minimal threat to human health and finable using BAT; -groundwater pollution is predicted to be restored in 60 years. Y 13.Mass balance calculation of substance Initial mass and groundwater residual mass estimates were not provided treated versus that remaining; by consultant.An estimated 2.5 lbs. (0.4 gal.)of toluene remains in soil. Y 14. Assumptions, parameters, calculations Consultant states site does not represent a significant environmental or and model used in risk assessments, and health risk. fate and transport modeling; Y 15. Rationale why conditions remaining at Soil and groundwater pollution is reportedly limited to the property site will not adversely impact water quality, boundaries.Land use(commercial)is not expected to change in the health, or other beneficial uses;and foreseeable future. WQGs will be reached by 2075. Groundwater plume is stable and slowly decreasing in concentration. By: JLB Comments:One UST containing toluene was 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: 4/14/15 exposure to groundwater,soil vapor, and soil, Regional Board staff recommend closure.