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BLE 1 -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Dame and Location: Universal Forest Products, 26200 Nowell Road, Thornton, San Joaquin County(RB#390063)
<br /> Y 1. Distance to production wells for municipal, domestic, A sensitive receptor survey In 2008 identified no water
<br /> agriculture, industry and other uses within 2000 feet of the site. supply wells within 2,000'of the site.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of One 10,000-gallon diesel UST was removed 6104. Soil
<br /> any former and existing tank systems, excavation contours and from the UST pit was over-excavated
<br /> sample locations, boring and monitoring well elevation
<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 42, the
<br /> diagrams; total depth investigated.
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal(quantity); approximately 687 tons of soil excavated during the
<br /> UST removal was transported to Forward Landfill,in
<br /> Manteca.
<br /> :YD 5. Monitoring wells remaining on-site, fate; Three monitoring wells(MW-1 through MW-3) will be properly abandoned.
<br /> S. Tabulated results of all groundwater Depth to groundwater varied from 7'to 12'bgs. Groundwater flow
<br /> , direction was towards the southwest. The consultant did not calculate
<br /> elevations and depths to water____
<br /> -----_w— w- . roundwater gradient the roundwaterisocontourmaps.
<br /> 7. Tabulated results of all sampling Maximum confirmation soil concentration on 6/04 was TPHd, 3,200 mg/kg.
<br /> and analyses: Maximum soil boring concentration on 3/05 was TPHg,94 mg/kg. In 1/09, soil
<br /> boring result was TPHd,42 mg/kg. In 3105,grab groundwater concentrations were
<br /> FYI Detection limits for confirmation TPHd, 57,000 ug/L;and TPHg,84 ug/L. In 1109,maximum groundwater monitoring
<br /> sampling result was TPHd, 130 ug/L.
<br /> Lead 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 /> reports.
<br /> ElLateral and Y❑Vertical extent of soil contamination
<br /> Lateral and M Vertical extent of groundwa ter 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 lead agency.
<br /> system;
<br /> 10.Reports/information EY Unauthorized Release Form QY QMRs 7 from 5106 to 1109
<br /> FE Well and boring logs 151PAR N❑ FRP � Other Supplemental Site Investigation(1/09);Case
<br /> Closure Summa 5/09
<br /> Y T11.Best Available Technology(BAT)used or an explanation for not using UST removal, over-excavation,and natural
<br /> BAT,' I attenuation.
<br /> Y 12, Reasons why background warms unattainable Minor residual soil contamination remains on-site.
<br /> .BA•T;-- — - -- — - -
<br /> y 13.Mass balance calculation of substance treated In 5109, the calculated mass removed from soil was TPHd,360 gallons
<br /> versus that remaining; and mass removed from groundwater, 0.8 gallons. Estimated
<br /> remaining soil mass was TPHd, 5 gallons and remaining mass in
<br /> groundwater, 0.28 gallons.
<br /> Y 14. Assumptions, parameters, calculations and The soil and soil vapor sample results(1109)show Region 2 ESLs
<br /> model used in risk assessments, and fate and (commercial,deep soil)were not exceeded. The site is located in a
<br /> transport modeling; commercially zoned area to the south of Thornton.
<br /> -y] 15. Rationale why conditions remaining at site will Soil contamination reportedly is limited in extent. Land use is not
<br /> not adversely impact water quality, health, or other expected to change in the foreseeable future.
<br /> beneficial uses;and
<br /> By: JLj Comments: One 10,000-gallon diesel UST was removed 6/04,and approximately 680 tons of soil were over-
<br /> excavated and transported offsite for disposal from the subject site. Based upon 5 quarters of groundwater
<br /> Date: monitoring showing a stable plume with declining concentrations, the limited extent of contamination
<br /> 7/7/2009 remaining in soil, no foreseeable changes in land use(commercial), and no soil and soil vapor ESLs
<br /> exceeded, Regional Board staff concur with San Joaquin County's Closure Recommendation.
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