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<br /> 0 TABLE 7 -CHECKLIST OF REQUIRED DA�
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and LocatiEarth9rains/Sa`ra Le0WIpatrick, 17175. Center St.Stockton,San Joaquin County(RB 11390804)
<br /> on:
<br /> �. Distance to production wells for municipal,domestic; A.2002 sensitive receptor survey reported six water supply
<br /> Y no heast within
<br /> 2,0001 of the Site.
<br /> dust and other uses within 2000 feet of the
<br /> wells nearest 1,T50 rt )
<br /> agriculture, industry The wells.are not threatened by this release:
<br /> I' site.
<br />'i _YJ2. Site maps, to scale, of area impacted showing locations of any former In 12-90,one 1,000-gallon gasoline UST was
<br /> and existing tank systems, excavation contours and sample locations, removed.
<br /> boring and monitoring well elevation contours, gradients, and nearby
<br /> surface waters, buildings,streets, and subsurface utilities;
<br /> site lithology consists of clay,silt,and sand to
<br /> Y 3. Figures depicting lithology(cross section), treatment system diagrams; 67',the total depth investigated.
<br /> T'ForwardLoendfill'in
<br /> pproximtely.,1yds. of excavated soil was transported to
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal Manteca,
<br /> (quantity):
<br /> Y 5. Monitoring wells remaining on-site, Eight(8)monitoring wells(MW-1 through MW-5 and MW-2A,MW-3A,and MW-5A)
<br /> and two(2)remediation wells(SP-1 and VW-1) were properly destroyed on
<br /> a e; 9/24112.
<br /> 6. Tabulated results of all groundwater Depth'to groundwater varied from 22'bgs to 30'bgs.Groundwater flow direction
<br /> varied from east to southeast. Groundwater gradient varied from 0.001 f0t to
<br /> elevations and depths to water,
<br /> 0.005 ft/ft
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports,including closure report.
<br /> and analyses:
<br /> QDetection limits for confirmation
<br /> sampling
<br /> 10- Lead analyses
<br /> 6. 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 /> IJ lateral and Vertical extent of soil contamination
<br /> MY Lateral and nY Vertical 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 I information 17Y Unauthorized Release Form 0 QMRs,(38) 7-99 to 10-10
<br /> FY] Well and boring logs 5 PAR FRP Other Closure Report(9-09),.Response To Comments
<br /> 3=i 4
<br /> Y 11.Best Available Technology(BAT)used or an exptanation USTs removal,SVE,AS,and natural attenuation.
<br /> for not using BAT;
<br /> Y 12. Reasons why background walls unattainable Residual soil and groundwater contamination remains.
<br /> BAT;
<br /> y 13.Mass balance calculation of substance treated Consultant estimated TPhf as 4,413 lbs. of TPN remain in soil and
<br /> 26 tbs remain in groundwater. SVE removed 190 tbs of TPN.
<br /> versus that balance
<br /> ;
<br /> 14. Assumptions,parameters, calculationsand A soil vapor survey was not required by the regulatory
<br /> agency. Soil'
<br /> Y
<br /> model used in risk assessments, and fate and failed Region 2 ESLs for direct exposure(DE)and gross
<br /> transportmodeling; contamination for TPlfg and DE for Benzene at 35'bgs, which is
<br /> below typical worker.depths.Consultant states site does not
<br /> represent a significant risk.Fate and transport(F&T)-modeling
<br /> showed in 20 years plume would not exceed 80'at 1 ppb benzene
<br /> concentration and benzene mass was reduced to 0.1 k
<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.Land use(commercial)is not expected to change in the
<br /> benelrcial uses;and foreseeable future. rime to reach WQGs estimated as 40 yrs.
<br /> By: JLB Comments:In 12-90,one 1,000-gallon gasoline UST was removed at the subject site.Residual soil and
<br /> groundwater contamination remains.Based upon the limited extent of contamination reported in soil and
<br /> Date: groundwater,groundwater reaching WQGs in a reasonable time frame, no foreseeable changes in future
<br /> 11129/2012 land use(commercial),and minimal risks from groundwater,soil vapor and soil,Regional Board staff concur
<br /> with San Joaquin County's Closure Recommendation.
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