SITE INFORMATION AND CORRESPONDENCE

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� I TABLE 1 - CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES E Site Name and Location: Quick N Save Arco,7200 South Ll Dorado Street San Joaquin County(Lustis#391084) N 1. Distance top wells for municipal, domestic, agriculture, industry and A sensitive receptor survey was not other uses within 2000 feet of the site; required. Y 2. Site maps, to scale, of area impacted showing locations of any former and existing tank systems, One 6,000-gallon UST; excavation contours and sample locations, boring and monitoring well elevation contours, one 8,000-gallon UST; gradients;.and nearby surface wafers, buildings, streets, and subsurface utilities, and one 12,000-gallon UST removed in 12/99. FY, 3. Figures depicting lithology(cross section), treatment system diagrams; Sail consists feet below grouu silty sands and clays to 43 nd surface(bgs), the maximum depth investigated. MN 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Excavated soil was reused as tank pit backfill. 5. Monitoring wells remaining on-site, fate; No monitoring wells were installed for investigation. _6_' a- re a is o 'N groundwater el a__M ns and depths f wdfe 'Groundwater was encountered-in-soil borings at approximately 33 feet bgs. LiLl 7. Tabulated results of all sampling and analyses: In 10/99,maximum soil concentrations in sample D6 were: TPHg; ii 825 mg/kg, Toluene; 6.95 mglkg, Ethelbenzene;373.55 mg/kg,and Detection limits for confirmation sampling Xylenes;6.5 mg/kg. Sample T2S:MTBE, 17.97 mg/kg. In 10199 all .1 %' ! groundwater samples were ND. On 6122104,all soil and groundwater Y Lead analyses samples were ND. 8. Concentration contours of contaminants found and those remaining in soil Soil impacts limited to vicinity of the and groundwater, and both on-site and off-site: former fuel dispensers, as defined by soil borings. Y❑ Lateral and Y❑ Vertical extent of soil contamination © Lateral and © Vertical extent of groundwater contamination 9. Zone of influence calculated and assumptions used for subsurface Based on the limited extent of soil remediation system and the zone of capture attained for the soil and contamination, an engineered remediation system was not required at this site. groundwater rernediation system; 10.Reports/information 0 Unauthorized Release Form ❑N QMRs(hates) �Y Well and boring logs PAR R FRP �Y Other,'Closure Summary Report Y 11,Best Available Technology(BAT) used or an explanation for not using BAT; Removal of gasoline US Ts and natural attenuation. Y 12.Reasons why background waars unattainable using BAT; Minor soil contamination remains on-site. - ....._ N 13.Mass balance calculation of substance treated versus that remaining; A mass balance for remaining pollution was a not calculated for soil :N::] 14. Assumptions, parameters, calculations and model used in A risk assessment was not required for this site. risk assessments, and fate and transport modeling; I, 15. Rationale why conditions remaining at site will not adversely Primary impact is to shallow soil(silt&clay)at 2 ft.bgs impact water quality, health, or other beneficial uses;and at dispenser sample location D6. Soil contamination is limited in extent and groundwater was encountered at 33 feet bgs. By: JLB/BK Comments:One 6 000-gallon UST, one 8,000-gallon UST;and one 12,000-gallon UST were removed in 12/99. Limited soil contamination was adequately characterized(laterally&vertically)by multiple sampling events. All Date: 2127106 impacts to soil are below current ESLs, with the exception of TPHg at 625 mg/kg(2 ft bgs). No structures are currently located on the property as the mini mart associated with the gas station was recently demolished. All gr7undwatersamples have been ND, as residual impacted soil is limited to approximately 10-15 feet bgs, 15 feet above historic high groundwater levels at the site."Additionally, vertical migration of constituents of concern is limited by the presence of a clayey silt layer approximately 15 feet bgs. Based on the limited extent of the remaining soil contamination. Reaional Board staff concur with San Joaauin Countv's Closure Recommendation. E ,