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ABLE 1 - CHECKLIST OF REQUIRED DATn
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Chevron 9-3232, 8660 Lower Sacramento Rd., Stockton, San Joaquin County (RS #390830)
<br />{ Y 1. Distance to production wells for municipal, domestic, A 2001 sensitive receptor survey identified two water
<br /> agriculture, industry and other uses within 2000 feet of the site, supply wells within the search area, one 2,000' to the
<br /> northeast and one 2,000' to the southeast of the Site.
<br /> y 2. Site maps, to scale, of area impacted showing locations of In March 1999, three 10,000-gallon gasoline and one
<br /> any former and existing tank systems, excavation contours and 1,000-gallon waste oil USTs were removed.
<br /> sample locations, boring and monitoring well elevation
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets, and subsurface utilities;
<br /> Y1 3. Figures depicting lithology (cross section), treatment system Site litho/ogy consists of clay, silt, and sand to 70', the
<br /> diagrams; total depth investigated.
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal (quantity); A total of 120 y -of excavated soil was disposed at
<br /> Forward Landfill, Manteca (80 yd9) and BFI, Livermore
<br /> 40 d9 .
<br /> YD 5. Monitoring wells remaining on-site, fate; Ten monitoring wells (MW-1 through MW-7 and MW-4D through MW-6D) will
<br /> be properly abandoned.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 31 ' to 45' bgs. Groundwater flow
<br /> elevations and depths to water, direction was towards the southeast, and groundwater gradient varied
<br /> from 0.001 to 0.02 ft/ft.
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports, including closure report.
<br /> and analyses:
<br /> Y❑ Detection limits for confirmation
<br /> sampling
<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 />'i
<br /> ❑Y Lateral and l Vertical extent of soil contamination reports.
<br /> Lateral and RY Vertical extent of groundwatercontamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation The regulatory agency did not require
<br /> system and the zone of capture attained for the soil and groundwater remediation active remediation.
<br /> system;
<br /> 10. Reports / information Unauthorized Release Form 0 QMRs 45 from 10/98 to 12/10
<br /> [5] Well and boring logs PAR ❑N FRP ❑Y Other Closure Report (8/10)
<br /> YJ 11 . Best Available Technology (BAT) used or an explanation for not US
<br /> removal, over-excavation, and natural
<br /> using BAT, attenuation.
<br /> I 12. Reasons why background was/is Minimal residual soil and groundwater contamination remains on-site.
<br /> ttainable using BAT,
<br /> Y1 13. Mass balance calculation of substance treated The consultant estimated initial TPH as 1,239 lbs in soil, and 178 lbs. in
<br /> versus that remaining; groundwater. Approximately 1.2 lbs TPH remain in groundwater.
<br /> Y 14. Assumptions, parameters, calculations and The consultant did not conduct a soil gas survey; however, TPHg,
<br /> 7
<br /> model used in risk assessments, and fate and benzene, and xylenes at 151, 40', and 15' bgs, and at over 50' from
<br /> transport modeling; station building, exceeded Region 2 commercial ESLs for direct
<br /> exposure and gross contamination in soil at depths below normal
<br /> worker contact. Water quality goals will be reached in 30 years.
<br /> Y 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 not expected to change in the foreseeable
<br /> other beneficial uses; and future. Vapor intrusion risk has been addressed. Plume is stable.
<br /> By: J Comments: In March 1999, three 10,000-gallon gasoline and one 1,000-gallon waste oil USTs were removed
<br /> 16 from the subject Site. Based upon 45 quarters of groundwater monitoring showing a stable plume with a
<br /> Date: slowly declining concentration trend, the limited extent of contamination remaining in soil and groundwater,
<br /> 3/2312011 no foreseeable changes in land use, and limited threats from groundwater, soil, and soil vapor intrusion,
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