SITE INFORMATION AND CORRESPONDENCE

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TABLE 1 -CHECKLIST OF REQUIRE[' -,TA FOR ,,, FURTHER ACTION REQUESTS AT UNDER4,_,,,)UND TANK SITES Site Name and Location: Three Palms Grocery, 6732 E. Highway 88, Stockton, San Joaquin County 1. Distance to production wells for municipal, domestic, In 1999 a well survey was performed and found 33 water supply Y agriculture. industry and other uses within 2000 feet of the site; wells within 2,000 feet of the site including an on-site domestic water supply well. No surface water bodies were found within 2,000 feet of the site. On-site domestic well was sampled 28 times from 1999 to 2011 and no petroleum hydrocarbons were detected. 2. Site maps, to scale, of area impacted showing locations of former Site maps include location of former tanks,monitoring and existing tank systems, excavation contours and sample locations, wells and soil and vapor sample locations. borings and monitoring wells elevation contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities; 3. Figures depicting lithology(cross Silts and sands to a depth of 24 feet bgs, course gravel present from about 24 to 29 feet section), treatment System diagrams; bgs. Silty sand and clay were found below the gravel to the total depth investigated of 90 feet bgs. Cross-sections were developed showing extent of contamination in soil Y and groundwater. 4. Stockpiled soil remaining on-Site or No information was provided regarding soil stockpiles at this site. San Joaquin County Y off-site disposal(quantity): will assure all soil is removed before closure of this case. 5. Monitoring wells remaining on-site, fate; Destruction of monitoring and vapor extraction wells will be requested once closure is determined appropriate. Y 6. Tabulated results of all groundwater Depth to groundwater from about 75 to 91 feet bgs. Groundwater flow in shallow g.w. elevations and depths to water; NE to SE at a gradient between 0.0005 and 0.0121 ft/ft. Y 7. Tabulated results of all sampling and analyses: MY Tabulated results were presented in reports. Lead levels were evaluated from Detection limits for confirmation sampling four soil samples, sample results were all below 5.5 mg/kg which probably FYI Lead analyses represent naturally occurring background levels of lead. Y 8. Concentration contours of contaminants found and those remaining in soil M groundwater. and both on-site and off--site: Horizontal extent of contaminant impacts were Lateral and ❑Y Vertical extent of soil contamination provided on site maps and in cross-section view. Lateral and FN Vertical extent of groundwater contamination Vertical delineation was not required. Depth to water is about 90 feet bgs and petroleum impacts to first water were below 210 ug/L. N 9. Zone of influence calculated and assumptions used for subsurface No zone of influence calculations were presented. remediation system and the zone of capture attained for the soil and groundwater remediation system. Y-1 10.Reports/information Y Unauthorized Release Form ❑Y QMRs Well logs were provided in Closure Request ❑Y Well and boring logs F]PAR FY FRP �Y Other Y 11.Best Available Technology(BAT) used or an Soil vapor extraction was implemented for a short period of time during Nov.and explanation for not using BAT. Dec. 2011 removed almost 3000 lbs. (480 gallons)of petroleum hydrocarbons. Y 12.Reasons why background was/is unattainable State Board requiring County to close case. using BAT. Y 13.Mass balance calculation of substance Cardno ATC consultants did not present calculations of remaining mass. treated versus that remaining; 14.Assumptions, parameters, calculations and model used Y in risk assessments, and fate and transport modeling: 15.Rationale why conditions remaining at site will not A soil gas intrusion study was performed in August 2012, determine that soil gas present in the subsurface does not represent a risk to on- adversely impact water quality, health, or other beneficial site occupants. Operation of SVE reduced risk to water quality. uses; and N 1 16.WET or TCLP results NA By. Comments: One 550-gallon waste oil tank was abandoned in-place by filling with sand and capped with concrete clC prior to 1984. In November 1986 a 1,000-gallon leaded gasoline tank was removed, in May 1989 a 1,000-gallon unleaded gasoline tank was filled with concrete and in February 2005 two remaining tanks, of unknown size and contents,were removed. Site Conceptual Model indicates the release likely occurred from the leaded gasoline tank. Waste oil analytes were not analyzedDate: JA Petroleum hydrocarbons constituents were not detected in samples collected from the domestic well on-site since first sampled in December 1999. Groundwater samples collected from two monitoring wells constructed as sentry wells ot V, for the on-site domestic well did not detect petroleum hydrocarbons since third quarter 2006. SVE was installed and operated and was successful in reducing the size of the subsurface petroleum hydrocarbon plume.