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%.WABLE 1 -CHECKLIST OF REQUIRED DATA-_,i
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Loc Place, 15600 Harlan Rd., Lathrop, San Joaquin County(RB#390763)
<br /> =y sensitiveA 2008 receptor survey stated no water supply I- Distance to production wells for municipal, domestic, wells are located within 2,000'of the Site.
<br /> agriculture, industry and other uses within 2000 feet of the site. ry 1998,one 12,000 diesel UST was removed;
<br /> V7 2. Site maps, to scale, of area impacted showing locations of In Februa
<br /> any former and existing tank systems, excavation contours and and in October 1998, one 6,000-gallon, one 8,000-gallon
<br /> sample locations, boring and monitoring well elevation and one 10,000-gallon gasolin.e USTs were removed.
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets, and subsurface utilities;
<br /> V� 3. Figures depicting lithology(cross section), treatment system Site lithology consists of clay,silt,and sand to 75', the
<br /> _.!_J diagrams; total depth investigated.
<br /> Y remaining] 4. Stockpiled soil on-site or off-site disposal(quantity); The fate of the excavated soil is not discussed in the
<br /> I available reports.
<br /> :Y] 5. Monitoring wells remaining on-site, fate; Twenty two monitoring wells(MW-1 through MW 95B)will be properly
<br /> abandoned.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 71 to 14'bgs. Groundwater flow
<br /> _YJ direction varied from northeast to northwest. Groundwater gradient
<br /> elevations and depths to water, -_ I varied from 0.0003 100.013-".
<br /> 7, Tabulated results of all sampling All data adequately tabularized in various reports,including closure report.
<br /> and analyses:
<br /> IMY1 Detection limits for confirmation
<br /> sampling
<br /> ElF Lead analyses
<br /> VJ
<br /> The extent of the identified
<br /> 8. Concentration contours of contaminants found and those remaining in soil and
<br /> groundwater, and both on-site and off-site: contamination shown in applicable
<br /> Fy_1 MV reports.
<br /> I Lateral and I I I Vertical extent of soil contamination
<br /> Lateral and Fy-lVertical extent of groundwater contamination
<br /> N� 9. Zone of influence calculated and assumptions used for subsurface remediation Pump and treat and DPE were pilot
<br /> system and the zone of capture attained for the soil and groundwater remediation tested and found not cost effective.
<br /> system" I -
<br /> 10.Reports linformation E Unauthorized Release Form RY QMRs 34 from 2100 to 6109
<br /> RY Well and boring logs RY PAR a FRP FY10ther NFAR(11109)
<br /> usirm BAT natural attenuation.
<br /> Y F-
<br /> 11,Best Available Technology(BAT)used or an explanation for not USTs removal,limited pump and treat(DPE,and
<br /> U12. Reasons why background wassfis Minor residual soil and groundwater contamination remains on-site,
<br /> tainable using BAT' and in groundwater offsite under residences and a business.
<br /> Y 13.Mass balance calculation-of-substance treated -The consultant did not estimate removed or-residual TPN in soil or
<br /> versus that remaining; groundwater,but did estimate 15 years to reach WQGs.
<br /> :7 14, Assumptions,parameters, calculations and The soil gas results did not exceeded Region 2 ESILs.
<br /> 1 model used in risk assessments, and fate and
<br /> transport modeling;
<br /> :Y:1 15, Rationale why conditions remaining at site Soil and groundwater contamination reportedly is limited in extent.
<br /> will not adversely impact water quality, health, or Land use(commercial)is not expected to change in the foreseeable
<br /> other beneficial uses, and future.
<br /> By: JLW B ' Comments:In February 1998,one 12,000 diesel UST was removed;and in October 1998, one 6,000-gallon,
<br /> one 8,000-gallon and one 10,000-gallon gasoline USTs were removed at the subject site.Based upon 34
<br /> Date: quarters of groundwater monitoring showing a stable plume with declining concentrations, the limited extent
<br /> 12/2/2009 of contamination remaining in soil and groundwater,no foreseeable changes in land use,and no threats
<br /> from soil and soil vapor intrusion,Regional Board staff concur with San Joaquin County's Closure
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