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A"-fABLE 1 -CHECKLIST OF REQUIRED DATAmw
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Chevron Station#9-4275, 2905 W. Ben Holt Dr., Stockton, San Joaquin County(RB#390343)
<br /> Y 1. Distance to production wells for municipal, domestic, A 2012 sensitive receptor survey reported no water
<br /> a riculture, industry and other uses within 2000 feet of the site. I supply wells within 2,000'of the Site.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of any former In 1-89, one 5,000-gallon gasoline, two 10,000-
<br /> and existing tank systems, excavation contours and sample locations, gallon gasoline and one 1,000-gallon waste oil
<br /> boring and monitoring well elevation contours, gradients, and nearby USTs were removed.In 6-05,one 10,000-gallon
<br /> surface waters, buildings, streets, and subsurface utilities; gasoline,and four 12,000-gallon gasoline USTs
<br /> were removed,and one 1,000-gallon unknown
<br /> (concrete)UST was crushed and disposed as
<br /> debris.
<br /> Y 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clay,silt,and sand to
<br /> 57, the total depth investigated.
<br /> N 4. Stockpiled soil remaining on-site or off-site disposal The fate of the 1989 and 2005 excavated soil was not discussed
<br /> (quantity); in the available reports.
<br /> Y 5. Monitoring wells remaining on-site, fate; Nine(9)remaining monitoring wells(MW-1R through MW-3R, MW-5R, MW-6,
<br /> MW-7R, MW-8, MW-9R,and MW-10)will be properly destroyed.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 6'bgs to 20'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 /> aDetection limits for confirmation
<br /> sampling
<br /> �Y 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 /> ElLateral and i Vertical extent of soil contamination
<br /> Lateral and Mverticai extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface Soil vapor extraction(SVE)and air sparging
<br /> remediation system and the zone of capture attained for the soil and (AS)were the engineered remediation.
<br /> groundwater remediation system;
<br /> 10.Reports/information QY Unauthorized Release Form QY QMRs(70)3-89 to 1-12
<br /> RY Well and boring logs ❑Y PAR ❑Y FRP FY] Other Closure Report(4-12)
<br /> _YJ 11.Best Available Technology(BAT) used or an explanation USTs removal, SVE/AS,and natural attenuation.
<br /> for not using BAT;
<br /> Y 12. Reasons why background wasps unattainable Residual soil and groundwater contamination remains on-site.
<br /> BAT,
<br /> Consultant estimated TPH mass removed as 70 lbs in soil by SVE.
<br /> Y 13.Mass balance calculation of substance treated
<br /> versus that remaining; Approximately 203.38-gal. TPH remain in soil and<2 lbs TPH
<br /> remain in groLindwater.
<br /> Y 14. Assumptions, parameters, calculations and Soil vapor was not tested. Soil failed Region 2 ESL(2.5'bgss
<br /> model used in risk assessments, and fate and dispenser; 15'bgs USTs)prior to remediation. Confirmation
<br /> transport modeling; borings were not advanced. Consultant states site(active station)
<br /> does not represent a significant risk.
<br /> 7Y15. 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: JLC Comments:In 1-89, one 5,000-gallon gasoline, two 10,000-gallon gasoline and one 1,000-gallon waste oil
<br /> USTs were removed. In 6-05, one 10,000-gallon gasoline,and four 12,000-gallon gasoline USTs were
<br /> Date: removed,and one 1,000-gallon unknown(concrete) UST was crushed and disposed as debris at the subject
<br /> 9/11/2012 site. Residual soil and groundwater contamination remains on-site. Based upon the limited extent of
<br /> contamination reported in soil and groundwater,a stable groundwater plume with declining concentrations,
<br /> no foreseeable changes in future land use(commercial),and minimal risks from soil vapor,soil and
<br /> groundwater, Regional Board staff concur with San Joaquin County's Closure Recommendation.
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