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- -TABLE I -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Chevron#9-8264, 3775 N. Tracy Blvd., Tracy, San Joaquin County(RB#390795)
<br /> Y1 1. Distance to production wells for municipal, domestic, A 1998 sensitive receptor survey map shows fourteen
<br /> agriculture, industry and other uses within 2000 feet of the site. supply wells are located within 2,000'of the Site. The
<br /> nearest well was onsite;however, a 2002 site
<br /> investigation could not find the well.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of In November 1995, two 10,000-gallon and one 6,000-
<br /> any former and existing tank systems, excavation contours and gallon gasoline,and one 1,500-gallon waste oil USTs
<br /> sample locations, boring and monitoring well elevation were removed.
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets, and subsurface utilities;
<br /> Y1 3. Figures depicting lithology(cross section), treatment system Site lithoiogy consists of clay, silt,and sand to 35', the
<br /> diagrams; total'depth investigated.
<br /> Y1 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Approximately 590 cubic yards of excavated soil was
<br /> transported to Redwood Landfill in Novato and to
<br /> Browing-Ferris OX Landfill in Mountain.
<br /> YJ 5. Monitoring wells remainingon-site, fate; Four monitoring wells(MW-1 through MW-4)will be properly abandoned.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 8'to 12'bgs. Groundwater flow
<br /> tr elevafions armed de�ttts"to gvarte, -direction-was-primarily-_towaEfheast.-Gr-ou ldw-ater gradient
<br /> varied from 0A02 to 0.006 ft/ft.
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports,including closure repoit
<br /> and analyses:
<br /> Detection limits for confirmation
<br /> sampling
<br /> 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 is shown in applicable
<br /> reports:
<br /> X Lateral and El 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 Over-excavation of soil and oxygen
<br /> system and the zone of capture attained for the soil and groundwater remediation injection into groundwater were the
<br /> system; approved remedlation.
<br /> 10.Reports/information Unauthorized Release Form 0 QMRs' 57 from 5/96 to 10/09
<br /> 0 Well and boring logs 0 PAR 0 FRP FY1 Other Closure Report,,.2110 Revised Closure Report,5110
<br /> YJ 11.Best Available Technology(BAT) used or an explanation for notUST removal, over-excavation, oxygen injection into
<br /> usin BAT,' monitoring wells,and natural attenuation.
<br /> Y 12. Reasons why background wasn's Minor•residual soil and groundwater contamination remain on-site.
<br /> ttainable using BAT,
<br /> LL
<br /> 7 ]Q_VaisbaI57c6 calculation of substance treated--The-consultant-estimates-109;6-lbs-of 1 PH were present in°siiprtart�
<br /> versus that remaining; remediation. Approximately 20 lbs. of TPH was removed from
<br /> groundwater, while 98.6 lbs. of TPH remain in soil and 5.4 lbs. of TPH
<br /> remain in groundwater.
<br /> Y 14. Assumptions, parameters, calculations and The soil exceeded the San Francisco Bay Regional Board PSLs for
<br /> model used in risk assessments, and fate and TPHg(830 mg/kg)for direct exposure and gross contamination. Due to
<br /> transport modeling; the depth (12.5), distance from building(>50'),and low residual soil
<br /> concentrations(no benzene in TPHg sample),a vapor intrusion
<br /> investigation was not required by the regulatory agency.
<br /> y15. 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(service station)is not expected to change in the foreseeable
<br /> other beneficial uses;and future. WQGs will be reached in 5 years.
<br /> By: JLB ' Comments:In November 1995, two 10,000-gallon and one 6,000-gallon gasoline, and one 1,500-gallon waste
<br /> oil USTs were removed from the subject site. Based upon 57 quarters of groundwater monitoring showing a
<br /> Date: stable plume with declining concentrations, the limited extent of contamination remaining in soil and
<br /> 711312010 groundwater, no foreseeable changes in land use, and minimal threats from soil vapor intrusion, direct
<br /> contact and gross contamination Regional Board staff concur with San Joacluin CountVs Closure
<br />
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