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ABLE 1 -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FUh I,.,,ER ACTION REQUESTS AT UNDERGROUF ANK SITES
<br /> Site Name and Location: City of Manteca Corporation Yard,210 E.Wetmore St.,Manteca,San Joaquin County(Lustis Case 390436)
<br /> Y Distance to production wells for municipal, domestic, A 2003 well survey reported 1 industrial well and 1 public well
<br /> culture, industry and other uses within 2000 feet of the site. exist 1,000 feet and 2,000 feet south of the site,respectively.
<br /> Y 2. Site maps, to scale, of area impacted showing locations Three 10,000-gallon gasoline USTs and associated
<br /> of any former and existing tank systems; excavation piping/dispensers were removed 8/99. TPH and MtBE were
<br /> contours and sample locations, boring and monitoring well detected in soil beneath the USTs. No new USTs were
<br /> elevation contours; gradients, and nearby surface wafers, installed.
<br /> buildings, streets, and subsurface utilities;
<br /> Y 3. Figures depicting lithology(cross section), treatment Site lithology consists of clay,silt, sand, and gravel to
<br /> system diagrams; 115 feet, the total depth investigated
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal(quantity); The fate of the excavated soil is'not.discussed in the
<br /> reports.
<br /> Y 5. Monitoring wells remaining on-life, fate; Ten monitoring wells(MW-1 through MW-10)and nine ozone injection wells
<br /> OW-1 through OW,-9 remaining on-site will be proper!y proper! abandoned.
<br /> YJ 6. Tabulated results of all groundwater
<br /> Depth to groundwater varied from 13 to 24 feet below ground surface
<br /> i
<br /> elevations and depths to water, (bgs). The groundwater gradient varied from 0.0007 to 0.005 ft/ft, and the
<br /> downgradient direction varied in all directions.
<br /> LYJ 7. Tabulated results.of a!1 sampling Maximum boring(4/00)sample soil concentrations were toluene, 0.025 mglkg and
<br /> and analyses:. MtBE, 1.6 mg/kg,_No soil after results exist. Maximum grab.groundwater
<br /> T conceent ons(4/00) were TPHg, 1,200 ug/L;benzene, 310 ug/L;and MtBE;
<br /> QDefection limits for confirmation 10,000 pg/L. In 3/08, all groundwater monitoring sample results were non-defect,
<br /> sampling and have remained non-detect since 5/07.
<br /> ❑Y 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 shown in applicable
<br /> reports.
<br /> 0 Lateral and Y❑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 The required engineered remediation for
<br /> system and the zone of capture attained for the soil and groundwater remediation groundwater was ozone injection.
<br /> s stem;
<br /> 10.Reports l information nY Unauthorized Release Form ITQMRS(25 from 1101 to 3108)
<br /> ❑Y Well and boring logs ❑Y PAR [_y] FRP [—Y] Other, Site Closure Request,6108;Ozone Injection Pilot Study,
<br /> 8105
<br /> Y 11.Best Available Technology(BAT)used or an explanation for not using Removal of USTs, ozone injection,and
<br /> BAT natural attenuation.
<br /> Z12. Reasons why background wads unattainable Limited soil contamination remains on-site.
<br /> ng BAT,-
<br /> Y 13.Mass balance calculation of substance treated The consultant did not estimate the amount of residual contamination
<br /> versus that remainin in soil or groundwater.
<br /> y 14. Assumptions, parameters, calculations and No so
<br /> ill ESLs were exceeded during ttFe osure Report ana yses. oi7��
<br /> model used in risk assessments, and fate and vapor intrusion was evaluated;and no threat was indicated due to the
<br /> transport modeling; distance(90 feet) from former US Ts to nearest building and low soil
<br /> concentrations.
<br /> Y 15. Rationale why conditions remaining at site will Soil contamination is limited in extent. Results of 25.quarters of
<br /> not adversely impact water quality, health, or other groundwater monitoring show a decreasing trend in concentrations to
<br /> beneficial uses;and non-defect.I WQOs have been reached.
<br /> By: JLB Comments: Three 10,000-gallon gasoline USTs and associated piping/dispensers were removed 8/99 at the
<br /> subject site. TPH and MtBE were detected in soil beneath the USTs. No new USTs were installed. Maximum
<br /> Date: boring(4/00)sample soil concentrations were toluene, 0.025 mglkg and MtBE, 1.6 mg/kg. No soil after results
<br /> 8/15/2008 exist. Maximum grab groundwater concentrations(4/00) were TPHg, 1,200 ug/L;benzene,310 ug/L;and MtBE;
<br /> 10,000 pg/L. In 3/08,all groundwater monitoring sample results were non-detect,and have remained non-
<br /> detect since 5/07. Based upon 25 quarters of declining groundwater concentrations to ND, no exceedence of
<br /> ESLs in soil for residual contamination, the lack of threat from vapor intrusion as a result of the distance from
<br /> the former USTs to the store, no anticipated changes in land use(City Yard), and the limited extent of
<br /> contamination present in sail, Regional Board staff concur with San Joaquin County's Closure
<br /> Recommendation.
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