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�d`ABLE 1 -CHECKLIST OF REQUIRED DATAJ
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: CalTrans Shop 10, 1603 B St, Stockton San Joaquin County(RB 11390135)
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<br /> Y1 1. Distance to production wells for municipal, domestic, A 2009 sensitive receptor survey stated 7 domestic water
<br /> agriculture, industry and other uses within 2000 feet of the site. wells are located within 2,000'of the Site,including one
<br /> 1,100'southwest and one 1,000'north, and likewise,
<br /> 4 municipal wells are within 2,000'of the Site, including
<br /> one 560'southeast ;
<br /> Y 2. Site maps, to scale, of area impacted showing locations of In February 1989, three 5,000-gallon gasoline and one
<br /> i any former and existing tank systems, excavation contours and 5,000-gallon diesel USTs were removed. in March 1989,
<br /> I sample locations, boring and monitoring well elevation one 1,000-gallon waste oil tank was removed. The Site
<br /> contours, gradients, and nearby surface waters, buildings, has been a Cal Trans repair and maintenance yard since
<br /> streets, and subsurface utilities; the 1940s.
<br /> Y1 3. Figures depicting lithology(cross section), treatment system Site litho'logy consists of clay,silt,sand, and gravel to
<br /> f diagrams; 901, the total depth investigated.
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<br /> Y 4. Stockpiied soil remaining on-site or off-site disposal(quantity); The fate of the excavated soil was not discussed in the
<br /> available repoifs.
<br /> Twelve monitoring wells(MW-9, MW--11 through MW-13,MW-14A, MW-16,
<br /> Y 5. Monitoring wells remaining on-site, fate; i
<br /> MW-19, MW-20, MW-24, MW-.25, VM,1, VM-2),and six remediation wells
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<br /> - S._W.-a,_and-VFW 1=and ViEWr2_will_be. ro erl. abandoned._�
<br /> 6. Tabulated results of all groundwater ` Depth to groundwater varied from 42'to 65'bgs. Groundwater flow
<br /> elevations and depths to water, direction varied from northwesi to southeast. Groundwater gradient
<br /> varied from 0.001 to 0.003 ft/ft.
<br /> 7. Tabulated results of all.sampling All data adequately tabularized in various reports, including closure report.
<br /> and analyses: l
<br /> Y❑ Detection limits for confirmation
<br /> sampling
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<br /> Lead analyses
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<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 shown in applicable
<br /> reports.
<br /> 0 Lateral and Y❑Vertical extent of soil contamination
<br /> Lateral and MY Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Soil vapor extraction and air sparging
<br /> system and the zone of capture attained for the soil and groundwater remediation were the engineered remediation.
<br /> system;
<br /> 10.Reports 1 information Unauthorized Release Form 0 QMRs 85 from 4187 to 5109
<br />. 0 Well and boring logs 0 PAR FYI FRP 0 Other Closure Report(12109)
<br /> Y I 11.Best Available Technology(BAT) used or an explanation for not USTs removal, SVE/AS, and natural attenuation.
<br /> usi2q BAT,'
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<br /> 71-1-2—Reasons-why background-was TMinorresidual=soil-rrrf groundwater contamination-remairrorr=ste:
<br /> ttainable using BAT,'
<br /> Y 13.Mass balance calculation of substance treated Approximately 28,150 pound of TPH were removed by SVE. The
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<br /> versus that remaining; consultant estimates 480 pounds of TPH remain in soil and 2.6 grams
<br /> f of TPH remain in groundwater.
<br /> Y 14. Assumptions,parameters, calculations and The consultant stated results"of soil vapor samples did not exceed
<br /> model used in risk assessments, and fate and ESLs or CHHSLs,and do not pose a risk from vapor intrusion. TPHd
<br /> transport modeling; exceeds gross contamination)and direct exposure ESLs for soil at 35'
<br /> b s, which is below de the normal!y associated with direct contact. '
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<br /> 15. Rationale why conditions remaining at site Soil and groundwater contamination reportedly are limited in extent. #
<br /> will not adversely impact water quality, health, or Land use(commercial)is notexpected to change in the foreseeable
<br /> other beneficial uses;and future. WQGs will be reached in 4.5 years.
<br /> By: JLB � Comments:In February 1989, three 5,000-gallon gasoline and one 5,000-gallon diesel USTs were removed.In
<br /> March 1908 one 1,000-gallon waste oil tank was removed. Based upon 85 quarters of groundwater
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<br /> monitoring showing a stable plume with declining concentrations,.ithe limited extent of contamination
<br /> 0 1 0 remaining in soil and groundwater, no foreseeable changesain land use,and minimal threats from soil vapor
<br />' intrusion direct contact and gross contamination Regional Board staff concur with San Joa uin County's
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