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'%,,,fABLE 1 -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location TARCO Station#2123, 2908 W. Ben Holt Dr., Stockton, San Joaquin County(RB#390002)
<br /> Y 1. Distance to production wells for municipal, domestic, A 2012 sensitive receptor survey reported no water
<br /> agriculture, industry and other uses within 2000 feet of the site. supply wells within 2,000'of the Site.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of any In 5-84, one unknown size/contents UST was removed.
<br /> former and existing tank systems, excavation contours and In 8-87, one 550-gallon waste oil UST was removed.In
<br /> sample locations, boring and monitoring well elevation contours, 9-91, one 1,000-gallon free product recovery tank was
<br /> gradients, and nearby surface waters, buildings, streets, and removed. In 3-99, one 10,000-gallon gasoline was
<br /> subsurface utilities; removed. In 8-02, one 550-gallon waste oil UST was
<br /> removed.
<br /> 7Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of clay, silt, and sand to 57, the
<br /> diagrams; total depth investigated.
<br /> N 4. Stockpiled soil remaining on-site or off-site disposal In 1999, approximately 450 tons of excavated soil was
<br /> (quantity); transported to BFI Landfill in Livermore.
<br /> (q 5. Monitoring wells remaining on-site, fate; Seventeen(17)remaining monitoring wells(MW-1 through MW-5, BHD-2,E-2
<br /> through E-6,E-9 through E-12, PRI, and PR-2)and twenty three(23)
<br /> remaining remediation wells(AS-1 through AS-11, V-1 through V-12)will be
<br /> properly destroyed.
<br /> 6: Tabulated results of all groundwater Depth to groundwater varied from 4'bgs to 22'bgs. Groundwater flow direction
<br /> elevations and depths to water, varied from northeast to northwest at a gradient of 0.001 ft/ft to 0.0009 ft/ft.
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports, including closure report.
<br /> and analyses:
<br /> EVIDetection limits for confirmation
<br /> sampling
<br /> QY Lead analyses
<br /> 8. Concentration contours of contaminants found and those remaining in The extent of the identified contamination is
<br /> soil and groundwater, and both on-site and off-site: described in the available reports.
<br /> ELateral and FV_1 Vertical extent of soil contamination
<br /> MY
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface Free product removal, groundwater
<br /> remediation system and the zone of capture attained for the soil and extraction (GWE), soil vapor extraction(SVE)
<br /> groundwater remediation system; and air sparging(AS) were the engineered
<br /> remediation.
<br /> 10.Reports/information EY Unauthorized Release Form ❑Y QMRs(93)8-88 to 1-12
<br /> ❑Y Well and boring logs EY PAR El FRP 10 Other Closure Report(4-12)
<br /> YJ 11.Best Available Technology (BAT) used or an explanation USTs removal, over-excavation, free product removal,
<br /> for not using BAT; I GWE, SVE/AS, and natural attenuation.
<br /> Y 12. Reasons why background waslls unattainable Residual soil and groundwater contamination remains on-site.
<br /> BAT;
<br /> Y 13.Mass balance calculation of substance treated Consultant estimated TPH mass removed as 3,980 lbs in soil by
<br /> versus that remaining; GWE, and SVE removed 4,897 lbs. Approximately 250.4 gal. TPH
<br /> remain in soil and<2 lbs TPH remain in groundwater.
<br /> Y 14. Assumptions, parameters, calculations and Soil vapor was not tested. Soil failed Region 2 ESL (10'bgs USTs)
<br /> model used in risk assessments, and fate and prior to remediation. Confirmation borings were not advanced.
<br /> transport modeling; Consultant states site(active station) does not represent a
<br /> si nificant risk.
<br /> Y 15. Rationale why conditions remaining at site will Soil and groundwater contamination reportedly are limited in
<br /> not adversely impact water quality, health, or other extent. Groundwater plume is stable and decreasing. Land use
<br /> beneficial uses;and (commercial)is not expected to change in the foreseeable future.
<br /> TPH in groundwater is estimated to reach WQGs in 2024.
<br /> By: JLB Comments:In 5-84, one unknown size%ontents UST was removed. In 8-87, one 550-gallon waste oil UST was
<br /> "r removed. In 9-91, one 1,000-gallon free product recovery tank was removed. In 3-99, one 10,000-gallon
<br /> Date: gasoline was removed. In 8-02, one 550-gallon waste oil UST was removed at the subject site. Residual soil
<br /> 9/11/2012 and groundwater contamination remains on-site. Based upon the limited extent of contamination reported in
<br /> soil and groundwater, a stable groundwater plume with declining concentrations, no foreseeable changes in
<br /> future land use(commercial), and minimal risks from soil vapor,soil and groundwater, Regional Board staff
<br /> concur with San Joaquin County's Closure Recommendation.
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