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TAW 1 - CHECKLIST OF REQUIREDRATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Gene Gabbard Inc.,640 N. E/Dorado St., Stockton San Joaquin County(Lustis#391005)
<br /> Y 1. Distance to production wells for municipal, domestic, A search of the State database GeoTracker shows
<br /> t agriculture, industry and other uses within 2000 feet of the no municipal supply and no private wells located
<br /> site; within 2000'of the site.
<br /> Y Site maps, to scale, of area impacted showing locations of any One 250-gallon waste oil UST was removed 3-97
<br /> former and existing tank systems, excavation contours and sample from the service bay inside of the former new car
<br /> locations,boring and monitoring well elevation contours, gradients, dealership.
<br /> and nearby surface waters, buildings, streets, and subsurface
<br /> utilities;
<br /> Y1 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clay,silt, and
<br /> sand to 40 feet, the total depth
<br /> investigated.
<br /> N 4. Stockpiled soil remaining on-site or off-site disposal(quantity); The fate of the excavated soil is not discussed in the
<br /> available reports.
<br /> :Y::] 5. Monitoring wells remaining on-site, fate; Seven monitoring wells(MW-1 through MW-7) were properly abandoned on
<br /> 26 June 2009.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 21 to 27 feet below ground surface
<br /> elevations and depths to water, (bgs). The groundwater gradient was 0.03 fUft, and the downgradtent
<br /> direction was towards the northeast.
<br /> 7. Tabulated results of all sampling and In 6198, maximum soil boring concentrations were TPHg, 1,800 mg/kg; TPHd,
<br /> analyses: 4,600 mg/kg; TRPH, 8,300 mg/kg;benzene, 4.6 mg/kg, toluene,35 mg/kg;
<br /> ElY ethylbenzene, 11 mg/kg;xylenes, 61 mg/kg, naphthalene, 39 mg/kg;and total
<br /> Detection limits for confirmation lead;3,500 mg/kg. No post-remediation soil samples were collected. Maximum
<br /> sampling grab groundwater monitoring concentrations in 6198 were TPHg, 4,500 pg/L;
<br /> TPHd, 510,000 ug/L; TRPH, 16,000,000 ug/L;benzene, 180 irg/L;toluene, 640 ug/L;
<br /> 0 Lead analyses ethylbenzene, 110 ug/L;xylenes, 570 pg/L, naphthalene, 680 ug/L; cis-1,2-DCE,
<br /> 32 ug/L;and total lead, 95 pg/L. In 9108, maximum groundwater monitoring
<br /> concentrations were TPHmo, 520 pg/L; TPHg,460 ug/L;benzene, 8.2 ug/L;
<br /> toluene, 2.4 ug/L;ethylbenzene, 5.8 ug/L;xylenes, 14 ug/L; MTBE, 0.6 ug/L;and
<br /> 1,2-DCA, 1.6 ug/L.
<br /> 8. concentration contours of contaminants found and those remaining in soil and The extent of contamination is
<br /> ndwater, and both on-s' and off-site: adequately defined by soil borings
<br /> Y Lateral and LJ Vertical extent of soil contamination and monitoring wells.
<br /> ©Lateral and ©Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation The regulatory agency required
<br /> system and the zone of capture attained for the soil and groundwater remediation mechanical bailing of free product
<br /> system; as the engineered remediation.
<br /> 10.Reports/information FY Unauthorized Release Form �Y QMRs(24 from 2000—2008)
<br /> BY Well and boring logs EY PAR ❑Y FRP Other;
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not using BAT,, Removal of UST, removal of free product,
<br /> and natural attenuation.
<br /> Y 12.Reasons why background wads unattainable using BAT; Limited soil contamination and groundwater pollution
<br /> remains on-site.
<br /> Y 13.Mass balance calculation of substance treated versus that Mass treated(groundwater) was estimated as TPH,
<br /> remaining; 10 gallons.
<br /> Y 14. Assumptions, parameters, calculations and model used in Where Region 2 soil ESLs were exceeded, the depth
<br /> risk assessments, and fate and transport modeling; (15 feet) of the residual soil contamination and building
<br /> construction (slab and high bays)show minimal risk to
<br /> human health. No changes are anticipated to City
<br /> zoning commercial or site use(repair shop).
<br /> y 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent. Results of 24
<br /> impact water quality, health, or other beneficial uses;and quarters of groundwater monitoring show decreasing
<br /> trend in concentrations.
<br /> By: JLB Comments: One 250-gallon waste oil UST was removed 3-97 from the service bay inside of the former new
<br /> car dealership at the subject site. Mechanical bailing proceeded until free product was no longer present in
<br /> Date: groundwater. Mass removed(groundwater) was estimated as TPH, 10 gallons.. Based upon a stable plume,
<br /> 7/9/2009 24 quarters of declining groundwater concentrations, acceptable risk from vapor intrusion or direct
<br /> exposure, and the limited extent of contamination present in soil and groundwater, Regional Board staff
<br /> recommends closure for the Site.
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