SITE INFORMATION AND CORRESPONDENCE

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UBLE 1 -CHECKLIST OF REQUIRED DATA O FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES Site Name and Location: Copper Enterprises,12470 Locke Road, Lockford, San Joaquin County(Lustis Case 391082) Y 1. Distance to production wells for municipal, domestic, Geotracker shows six private wells within 2000 feet of the agriculture, industry and other uses within 2000 feet of the site. site. Distances and directions from site to private wells are not available on Geotracker. Y 2. Site maps, to scale, of area impacted showing locations of One 500-gallon gasoline UST was removed 8199. A any former and existing tank systems, excavation contours and concrete fuel oil bunker UST was closed in place 8199. sample locations, boring and monitoring well elevation Subsequently soil was overexcavated 11199 below the contours, gradients, and nearby surface waters, buildings, gasoline UST. streets, and subsurface utilities; Y 3. Figures depicting lithology(cross section), treatment system Site lithology was not described in reports. The total diagrams; depth investigated was approximately 15 feet. Y 4. Stockpiled soil remaining on-site or off-site disposal(quantity); approximately 30 cubic yards of over-excavated soil was removed, aerated, tested and remains(County approved)onsite(2100). Concrete bunker fuel product r and rinsate were transported offsite for dis osal. Y 5. Monitoringwells remaining on-site, fate; No monitoring wells were required or installed for this investigation. Y1 dwate -Depth°to-groundwater-wasreported•approximately-90-to-400- - feet-below- 6. Tabulated results of all grounr - ` elevations and depths to water,' ground surface(bgs). The reported regional groundwater flow direction is towards the south. 7. Tabulated results of all sampling In 8199, the maximum pre-remediation sail samples were TPHg, 690 mg/kg; and analyses: ethylbenzene, 0.15 mg/kg;and xylenes, 1.1 mg/kg. All confirmation soil borings f concentrations were ND in 8/99(under bunker UST)and in 11//99(under Detection limits for confirmation overexacavated gasoline UST). No groundwater samples were taken. -- sampling j QY 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 is described in applicable reports. _ Lateral and Y❑Vertical extent of soil contamination Lateral and FNIVertical extent of groundwater contamination ' 9. Zone of influence calculated and assumptions used for subsurface remediation Overexcavation to 15 feet bgs and onsite x system and the zone of capture attained for the soil and groundwater remediation aeration of soil were the required system; en ineered remediation. 10.Reports/information ❑Y Unauthorized Release Form ❑N QMRs WeIi and boring logs PAR IN Other f Y 11.Best Available Technology(BAT) used or an explanation for not using Removal of UST, overexcavation and soil BAT; aeration (gasoline), clean and inert fill __.(hunker). w Y 12. Reasons why background was<s unattainable No residual soil contamination detected on-site. Regional depth to BAT groundwater is approximately 90 to 100 feet. Y:1 13.Mass balance calculation of substance treated None calculated. versus that remaining; 714. Assumptions, parameters, calculations and No Region 2 ESLs were exceeded after remediation. model used in risk assessments, and fate and transport modeling; Y 15. Rationale why conditions remaining at site will Soil contamination was limited in extent and reported as remediated not adversely impact water quality, health, or other by aeration to ND levels. beneficial uses;and By: JL Comments: One 500-gallon gasoline UST was removed and one concrete fuel oil bunker was closed in place in l 8/99. In 8/99, the maximum gasoline UST pre-remediation soil samples were TPHg, 690 mg/kg;ethylbenzene, 0.15 Date: mg/kg;and xylenes, 1.1 mg/kg. No groundwater samples were taken. Subsequently soil was overexcavated below 4/21/2008 the gasoline UST. Approximately 30 cubic yards of over-excavated soil was removed, aerated, and spread onsite (2/00). All confirmation soil borings concentrations were ND in 8/99(under bunker UST) and in 11//99(after overexacavation of gasoline UST). Based upon the limited extent of contamination present in soil before remediation, no contamination detected after remediation, and the lack of a threat to groundwater and from soil vapor intrusion, Regional Board staff concur with San Joaquin County's Closure Recommendation.