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<br /> BLE 1 -CHECKLIST OF REQUIRED DATAU-,
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name,and Location: Sinclair Trucking,3780 Linne Road,Tracy,San Joaquin County(Lustis Case 0390133)
<br /> Y 1. Distance to production wells for municipal, domestic, agriculture, industry and other uses There are 15 drinking water
<br /> within 2000 feet of the site; wells within 2,000 feet of the
<br /> site. The onsite domestic
<br /> well(210'NNE of site)has
<br /> consistent) been ND.
<br /> 1—Y-1 Site maps, to scale, of area impacted showing locations of any former and existing tank One 350-gallon gasoline UST
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation was removed"T"
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities
<br /> Y1 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of silt;sand, and
<br /> clay to 35 feet, the total depth
<br /> investigated.
<br /> _Y1 4. Stockpiled soil remaining on-site or off-site disposal(quantity);_ Approximately 400 cubic yards of soil removed was
<br /> transported to Forward Landfill in Manteca.
<br /> Y 5. Monitoring wells remaining on-site,'fate; Six monitoring wells(MIM-1 through.MW-5 and MW-101), remaining on-site,
<br /> will be property abandoned.' -
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 8 to 12.feet below ground surface(bgs). The
<br /> elevations and depths to wafer, groundwater dongradient direction was reported to vary from North to East.
<br /> 7. Tabulated results of all sampling and In 4/87, maximum soil'concenfrations were: TPHg, 13,500 mg/kg; TPHd,
<br /> analyses: 20 mg/kg;benzene, 1171,000:mg/kg;toluene, 630,000 mg/kg;ethylbenzene,
<br /> Y 330,000 mg/kg;and xylenes, 1,080,000 mg/kg. In 3/05 maximum soil confirmation
<br /> Detection limits for confirmation sample results.were: TPHg, 2,300-mg/kg;benzene, 11 mg/kg;toluene, 84 mg/kg;
<br /> sampling ethylbenzene,45 Ing/kg;and xylenes, 220 mg/kg. Maximum groundwater
<br /> monitoring concentrations in 1/97 were: TPHg, 6,160 ug/L;benzene, 730 ug/L';
<br /> ❑Y Lead analyses toluene,410 ug1L;ethylbenzene, 210 ug/L;and xylenes,530 ug/L. In 1/07;
<br /> maximum groundwater monitoring concentrations were: TPHg, 400 ug/L,
<br /> benzene,4.5 ug/L, toluene,..1.0 u /L, ethylbenzene, 18 u 7L;and xylenes, 5.7 ug/L.
<br /> 8. Concentration contours of contaminants found and those remaining in soil and The extent of contamination is
<br /> roundwater, and both on-site and off-site: adequately defined by soil borings
<br /> e Y Lateral_and Y Vertical extent of soil contarriination and monitoring wells. _
<br /> 'Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Soil overexcavation and natural ,
<br /> system and the zone of capture attained for the soil and groundwater remediation attenuation were the required
<br /> system;', ' remedial actions.
<br /> 10.Reports/information �Y .Unauthorized Release Form QMRs(24 from 1997-2007)
<br /> QY Well and boring logs 0 PAR FYI FRP Other, Site Conceptual Model and 2 Soil Gas Rpts.
<br /> Y11.8esf Available Technology(BAT)used or an explanation for.not using BAT; BAT was soil removal and natural
<br /> attenuation.
<br /> Y 12.Reasons why background waslis unattainable using BAT, Localised soil contamination and groundwater pollution
<br /> remain on-site..
<br /> y 13.Mass balance calculation of substance treated,versus that . Approximately 2,645 lbs, of the estimated 4,506 lbs. of
<br /> remainiri ; TPHg soil contamination remain on-site.
<br /> Y 14. Assumptions, parameters, calculations.and model used in The latest data show that soil gas ESLs are not
<br /> risk assessments;and fate and transport modeling; exceeded. Water Quality'Goals are exceeded for TPHg
<br /> and benzene. The consultant estimates that-WQGs will
<br /> be reached in one year
<br /> Y 15. Rationale why conditions remaining at site will not adversely Soil contamination was limited in extent and residual
<br /> .impact water quality, health, or other beneficial uses;and contamination will continue to decline. Results of 24
<br /> quarters of groundwater monitoring show a decreasing
<br /> trend in concentrations.
<br /> By: JLB . ., , Comments: One 350-gallon gasoline.UST'was removed 3187 from the subject site. Remediation consisted of
<br /> overexcavation of 400 cubic yards of contaminated soil. Although approximately 2,645 lbs. of the estimated 4,506
<br /> Date lbs. of TPHg soil contamination remain on-site, declining groundwater concentrations show TPHg is not continuing to
<br /> 6/2812007 leach into groundwater at the pre-excavation rate. Additional soil gas sampling, conducted at the Regional Board
<br /> staffs request, show Region 2 soil.gas ESLs are not exceeded. Based upon 24 quarters of declining groundwater
<br /> concentrations, no threats from vapor intrusion, and the localized extent of contamination, Regional Board staff
<br /> concur with San Joaquin County's Closure Recommendation.
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