SITE INFORMATION AND CORRESPONDENCE

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i r !F E 1 — CHECKLIST OF REQUIREATA FOR NO FURT�ACTION REQUESTS AT UNDERGROUND TANK SiTES Site Name and Location: California WeldingSupply, 1000 East 11th Street,Tracy, Sart Joaquin County YY ]. Distance to production wells for municipal, domestic, agriculture, industry Ik 32 wells were identified within about 2000: and other uses within 2000 feet of the site; ! The nearest well is on-site and analysis i does ' ., not show any contamination in gw. Y02. Site maps, to scale of area impacted showing locations of former and existing tng tank systems, maps show the three excavation contours and sample locations,boring and monitoring well elevation contours, monitoring wells and the gradients, and nearby surface waters, buildings, streets, and subsurface utilities; areas of excavation activities. Y� 3. Figures depicting lithology(cross section);treatment system diagrams; it Soil boring logs and cross sections in assessment report(8/96) 4. Stockpiled soil remaining on-site or off--site disposal(quantity); 1 Q5. Monitoring wells remaining on-site, fate; 3 monitoring wells were installed on-site. SJCEHD will direct the destruction of the wells before granting final closure. NA 6. Tabulated results of all groundwater elevations and depths to water, Hlsforic groundwater elevation reported between 6 and 10'bgs. El 7.Tabulated results of all sampling and analyses: Initial soil sample reported 7192 mg/Kg(ppm) TPHd, 1972 ppm TPHg, and lower conc. BTEX.'Grab water samples contained elevated conc Eloflimits for confirmation sampling of contam,however, monitoring well samples were ND for all quarters. Lead analyses E 0 8. Concentration contours of contaminants found and those remaining in soil I,':' Soil contamination appears to have been Ygroundwater, and bot -site and off-site: it isolated to the UST and disp. areas. Lateral and L' I Vertical extent of soil contamination Groundwater contamination was initially Y❑ defected in grab gw samples,but never Lateral and Vertical extent of groundwater contamination E detected in monitoring well samples. NA 9.Zone of influence calculated and assumptions used for subsurface i N/A F remediation system and the zone of capture attained for the soil and groundwater remediation system; } FY-3. 10.Reports/information 0 Unauthorized Release Form Y]QMRs(Dates) GW data incorporated in other reports �i Y] Well and boring logs Y❑ PAR 8/96 ❑N FRP Y❑Other(report name)Closure Summary Report(12/98) i YD 11.Best Available Technology(BAT) used or an explanation for not using BA T; Overexcavation of about 200 cubic yards of contaminated soil was BAT. FNA] 12.Reasons why background waslis:unattainable-using BAT,•'-* N/A 0 13.Mass balance calculation of substance treated versus that remaining; '5.2 Ib. (0.86 gals)of TPHg, 8.8 lb. (1.20 gals)of jPHd,and 0.061b.(0.008 gals)of benzene HA 14.Assumptions,parameters, calculations and model used in risk N/A ; assessments, and fate and transport modeling; Y� 15.Rationale why conditions remaining at site will not adversely Remaining contamination is present in soil only. No impact water quality, health, or other beneficial uses,and groundwater contamination was identified in MWs or the on-site domestic well 0 16.WET or TCLP results li EI By.,MR Comments: Overexcavation removed a significant mass of soil contamination from the site. Three monitoring wells were installed and sampled on multiple occasions and did not contain elevated concentration of contamination. The Date: 6/2199 on-site monitoring well was sampled and did not contain detectable contamination. Less than 2 gallons of TPHg, TPHd, and benzene are estimated to remain in soil below the site.,Remaining contamination does not appear to e� a� :E j d