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ABLE 1 -CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND'TANK SITES Site Name and Location: Edison high School, 1425 South Center Street, Stockton, San Joaquin County Y I. Distance to production wells for municipal, domestic, agriculture, industry Soil case only. County staff states in theirClosure Summary that drinking water wells and and other uses within 2000 feet of the site; surface waters are not affected by the UST release. 0 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems, .In 1990,one 10,000-gallon diesel excavation co.Ontours and sample locations, boring and monitoring well elevation contours, and one 500-gallon gasoline tank were removed from the gradients, and nearby surface waters, buildings, streets, and subsurface utilities, site. Y� 3. Figures depicting litholo cross section treatment system diagrams; No treatment system was used. g p� g 9y( ), y d. Stockpiled soil remaining on-site or off-site disposal(quantity); E cavated soil was returned to the tank pits. 0 5. Monitoring wells remaining on-site, fate; No monitoring wells were installed at the site. 0 6. Tabulated results of all roundwater elevations and de the to water, Groundwater elevations were 20 feet bgs in 1993 and Y _ _ _w _ 9.r--�-�� f� _ _ _ 35•feet-bgs in`1986,with-an easted " o;w'dlre-ation. --- T 7. Tabulated results of all sampling and analyses: in 1990, TPHd as igh as 430 mg/kg were detected in soil borings from beneath Y the diesel tank. In 1999, two soil borings were installed in the proximal location ❑ Detection limits for confirmation sampling of the 1990 boring s. Unidentified hydrocarbons with concentrations up to Y 7,900 mg/kg were etected in the soil samples. Contaminants were not Lead analyses detected below 20 feet Groundwater was not encountered during both soil- PTI boring activities. Chromatograms did not show evidence of oxygenates. 8. Concentration contours bf contaminants found and those remaining in so!! N and groundwater, and both on-site and off-site: Lateral and Y❑ Vertical extent of soil contamination QLateral and 0 Vertical extent of groundwater contamination 9. Zone of influence calculated and assumptions used for subsurface The limit of the soil excavation is depicted in the remediation system and the zone of capture attained for the soil and Subsurface Investigation Summary Report groundwater remediation system; 0 10.Reports/information [9 Unauthorized Release Form ElQMRs(Dates) 2/96 -8/99 Y Well and boring logs EIPAR Y❑ FRP Other(report name) Investigation Summary Report 17-1 11.Best Available Technology(BAT) used or an explanation for not us! g BAT; The tanks were removed from the site. -r 0=f2�Reasons-why background-wasiis-unattainable using BAT; 0 13.Mass balance calculation of substance treated versus that remainin 7, None submitted. El14.Assumptions,parameters, calculations and model used in risk assessments, and fate and transport modeling, 0 15.Rationale why conditions remaining at site will not adversely Investigations show that contaminants did not migrate vertically impact water quality, health, or other beneficial uses;and mare than 20 feet bgs,strongly suggesting that groundwater wa s not impacted. N 16.WET or TCLP results By: 9 7- �, Comments. During the removal of the diesel tank, elevated levels of TPHd and low levels of ethylbenzene and xylene were detected in soil samples. in 1999, two angle borings were drilled lo 30 feet below the former diesel tank. Moderate levels of an Date. unidentifiable hydrocarbon were detected in three soil samples. The highest concentration was detected at 15 feet bgs and' attenuated with depth. No contaminant associated with the forme tank release was detected below 20 feet. BTEX constituents were non-detect and groundwater was not encountered during the investigations. At the request of County staff, Sequoia Analytical �� Laboratory reviewed the chromatograms from the 1999 soil-same'ng event and concluded that MTBE was not present in the samples above laboratory detection limits. Based on the minimal liesel impacts to shallow soil and the absence of MTBE and STEX contaminants, staff concurs with San Joaquin County closure recommendation.