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<br /> "ve TABLE 1 -CHECKLIST OF REQUIRED DA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROt)WD TANK SITES
<br /> Site Name and Location: Former Curtiss PontiaclCadiflac,2450 Toste Rd., Tracy,San Joaquin CountyRB#3g
<br /> ( 0658)
<br /> Y 1. Distance to production wells for municipal,domestic,agriculture, A 2011 sensitive receptor survey reported one water
<br /> industry and other uses within 2000 feet of the site. supply(1,400'northwest)andfour domestic wells
<br /> (nearest are onsite and 3001 south)within 2,000'of the
<br /> 2. Site maps, to scale, of area impacted showing locations of any lnr T-9?h#hrree 1,00U gal on gasoline USTs wes are not�treatened bv this re
<br /> former and existing tank systems, excavation contours and sample removed.
<br /> locations,boring and monitoring well elevation contours, gradients;
<br /> and nearby surface waters, buildings,streets, and subsurface
<br /> utifi les;
<br /> Y 3. Figures depicting lithology(cross section), treatment system site
<br /> diagrams: T0, lithotogy consists of clay,sift,sand,and grave!to
<br /> the total depth investigated.
<br /> Y 4. Stockpiled soil remaining on-site or off:site disposal Approximately 1,310 y excavated soli was transported to
<br /> uanti Forward Landfill in Manteca.
<br /> Y 5. Monitoring wells remaining on-site;fate; Nine(9)monitoring welts(MW 1 A,MW 1 B,MW-2A,MW-2B,and MW-3
<br /> through MW-T)and ten(10)treatment wells(oW-1 through OW-10)will be
<br /> ro erl destro ed
<br /> 6. Tabulated results of all groundwater. Depth to groundwater varied from 4'bgs to 8'bgs- Groundwater flow
<br /> eleVatlons and de 'ths to wafer, direction varied from northwest to north-eastat a gradient of 0.0 Rift.
<br /> T. Tabulated results of all sampling All data adequately tabularized in various reports,including closure report
<br /> and analyses:
<br /> MV
<br /> Detection limits for confirmation
<br /> sampling
<br /> QLead analyses
<br /> 8. 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
<br /> FV1available reports.
<br /> LLJ Lateral and FY]Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Over-excavation and ozone injection
<br /> system and the zone of capture attained for the soil and groundwater reme#iation were the engineered remedia#ion.
<br /> system;
<br /> 10.Reports/information 0 Unauthorized Release Form QMRs(4fi)2-98 to 12-t 0
<br /> E Welland boring logs U PAR � FRP o Other Closure Report(1-92)
<br /> Y 11.Best Available Technology-(BAT)used or an explanation for not using USTs removal, over-excavation,ozone
<br /> 11.B injec#ion,and natural attenuation.
<br /> y 12. Reasons why background wastis unattainable Residual soil and groundwater contamination remains on-site.
<br /> BAT,'
<br /> 13.Mass balance calculation of substance treated Consultant estimated 1,goodbs TPH removed by over-excavation.
<br /> versus#hof remaining; Approximately 0:234 Ibs of TPH"remain in groundwater and-397 lbs
<br /> TPN remain in soil
<br /> Y--14. Assumptions,parameters, calculations and soil vapor was not measured,due to high water table,distance to
<br /> model used in risk assessments, and fate and showroom(30')and paved surface.Soil results(TPH9)failed ESLs for
<br /> transport modeling; gross contamination and direct contact at 8'bgs,below the water
<br /> table and typical worker depth. Consultant states site does not
<br /> represent a significant risk.
<br /> 15. Rationale why conditions remaining at site will soil and groundwater contamination reportedly are limited in extent
<br /> not adversely impact water qualily, health, or other Land use(commercial)is not expected to change in the foreseeable
<br /> beneficial uses;and future. TPN in groundwater is estimated to reach WQCs in 4 years.
<br /> By, JLB Comments:in 7-91, three 1,000-gallon gasoline USTs were removed at the subject site.Residual soil and
<br /> groundwater contamination remains on-site.Based upon the limited extent of contamination reported in soil
<br /> Date: and groundwater,a stable groundwater plume with declining concentrations,no foreseeable changes in
<br /> 311912012 future land use(industrial), 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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