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'ABLE 1 -CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Arroyo's Smog Shop,3012 E. Waterloo Rd., Stockton,San Joaquin County(RB#391158) Y 1. Distance to production wells for municipal, domestic, A 2013 sensitive receptor survey reported three(3) agriculture,industry and other uses within 2000 feet of the site. water supply wells located 2,000'to the south, west, and north,respectively. None of the wells are threatened by the release. Y 2. Site maps, to scale,of area impacted showing locations of any In 9/98, three 4,000-gallon gasoline and one former and existing tank systems, excavation contours and 550-gallon waste oil USTs were removed. Site maps sample locations,boring and monitoring well elevation and 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 70', the total depth investigated. section), treatment system diagrams; No treatment system was constructed. Y 4.Stockpiled soil remaining on-site Approximately 18 tons of over-excavated soil was reportedly disposed at or off-site disposal uanti or Waste Management, Kettleman Hills Facility near Kettleman City. l5.Monitoring wells remaining on-site, Three(3)monitoring wells(MW-1 through MW-3)will be properly destroyed prior I to closure. 6. Tabulated results of all groundwater Depth to groundwater varied from 42'bgs to 59'bgs. Groundwater flow elevations and depths to water; direction was predominantly southwest(also southeast and northwest). Groundwater gradient varied from 0.001 ft/ft to 0.014 ft/ft. 7. Tabulated results of all sampling All data adequately tabularized in various reports-including analysis for waste oil and analyses: analytes. Y❑ 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: petroleum contamination are confined to the property limits. _ 0 Lateral and 0 Vertical extent of soil contamination FYI Lateral and FYI 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 E Unauthorized Release Form [0 QMRs(9)8-05 to 12-12 R Well and boring logs PAR FRP FV-1 Other No Further Action Report,5-13 YJ 11.Best Available Technology(BAT)used or an Leak was stopped by removing tanks, use of additional explanation for not using BAT; cleanup technology was not needed to be protective of human health and the environment. Unable Reasons why background was/is not Soil contamination does not present a threat to human health and UUnable usin BAT; groundwater pollution is predicted to be restored in 22 years. Y 13.Mass balance calculation of substance Consultant estimated residual TPH mass as 26.9 lbs.in soil and treated versus that remaining; 0.35 lbs.in groundwater. 7I, 14. Assumptions,parameters, calculations Site passed LTCP and Region 2 ESLs above 25'bgs(TPHg,500 mg/kg and model used in risk assessments,and fate failed ESL direct contact,450 mg/kg at 25'bgs), which is below typical and transport modeling; worker depths. Consultant states site does not represent a significant environmental or health risk. Y 1 15. Rationale why conditions remaining at Soil and groundwater contamination reportedly are onsite.Land use site will not adversely impact water quality, (commercial)is not expected to change in the foreseeable future. WQGs health,or other beneficial uses;and will be reached by 2035. Groundwater plume is stable and decreasing in concentration. By: JL8 Comments:In 9/98, three 4,000-gallon gasoline and one 550-gallon waste oil USTs were removed at the subject site.Based on the stable and declining concentrations in groundwater,no foreseeable changes in Date: future land use(commercial),and no risks from-soil vapor and soil,Regional Board staff concur with San 7/22/2013 Joaquin County's Closure Recommendation.