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<br /> `��ABLE 7 -CHECKLIST OF REQUIRED DATI
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: I Boyd Service Center, 560 Tracy Blvd., Tracy, San Joaquin County(RB 11390904)
<br /> Y 1. Distance to production wells for municipal,'domestic, , A 2003 sensitive receptor survey reported three
<br /> agriculture, industry and other uses within 2000 feet of the site. municipal supply wells within 2,000'of the site. The
<br /> nearest well is onsite and 200'to the northwest. The wells
<br /> are not threatened by the USTs release.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of In 12198, one 5,000-gallon diesel and two 8,000-gallon
<br /> any former and existing tank systems, excavation contours and gasoline USTs and associated dispenser and piping were
<br /> sample locations, boring and monitoring well elevation removed.
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets, and'subsurface utilities;
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of clay, silt and sand to 35; the
<br /> diagrams, total depth investigated.
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal (quantity); Approximately 40 yds3 of excavated soil was returned
<br /> to the tank pit. There is no discussion whether the soil
<br /> [wasremediated prior to reuse.
<br /> Y 5. Monitoring wells remaining on-site, fate;
<br /> Four(4)monitoring wells(MW-1 through MW-4) will be properly destroyed.
<br /> S. Tabulated results of all groundwater Depth to groundwater varied from 14'bgs to 15'bgs. Groundwater
<br /> elevations and depths to water,, gradient was 0.003 ft/ft. Groundwater flow direction was towards the
<br /> northwest.
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports, including closure report.
<br /> and analyses:
<br /> Y❑ Detection limits for confirmation
<br /> sampling
<br /> �Y Lead analyses
<br /> $. Concentration contours of contaminants found and those remaining in soil and The extent of the identified
<br /> groundwater,and both on-site and off-site: contamination is described in the IS
<br /> available reports.
<br /> Y❑Lateral and Y❑Vertical extent of soil contamination L
<br /> Lateral and FlVertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation An engineered remediation was not
<br /> system and the zone of capture attained for the soil and groundwater remediation required by the regulatory agency.
<br /> system;
<br /> 10.Reports I information IS] Unauthorized Release Form EY Q M R s (4)2109 to 2111
<br /> El Well and boring logs MY PAR H FRP rY Other Closure Report(6-09)
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not using USTs removal and natural attenuation.
<br /> BAT;
<br /> Y 12. Reasons why background wasris unattainable Minor residual soil and groundwater contamination remains on-site.
<br /> BAT;
<br /> N 13.Mass balance calculation of substance treated The consultant did not estimate mass in soil or groundwater.
<br /> versus that remainin ,-
<br /> I,
<br /> , 14. Assumptions, parameters, calculations and Soil ESLs were exceeded for TPHg gross contamination and direct
<br /> model used in risk assessments, and fate and contact at 14.5'bgs, which is below typical worker exposure depth.
<br /> transport modeling; The Site is a city maintenance yard and the USTs were 40'to 50'from
<br /> ara a and office building, res ectivel .
<br /> Y 15. Rationale why conditions remaining at site will Soil and groundwater contamination reportedly are limited in extent.
<br /> not adversely impact water quality, health, or other Land use(maintenance yard)is not expected to change in the
<br /> beneficial uses;and foreseeable future. TPH is estimated to reach WQGs in 2030.
<br /> By: JLB 1 Comments:In 12198, one 5,000-gallon diesel and two 8,000-gallon gasoline USTs and associated dispenser
<br /> � and piping were removed at the subject Site.Minor residual soil and groundwater contamination remains
<br /> Date: on-site. Based upon the limited extent of contamination reported in soil and groundwater,a stable
<br /> 11/23/2011 groundwater plume with slowly declining concentrations, no foreseeable changes in future land use
<br /> (commercial), and minimal risks from soil,soil vapor, and groundwater, Regional Board staff concur with
<br /> San Joaquin County's Closure Recommendation.
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