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ABLE 1 -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION.'REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Tracy Airport, 29633 Tracy Blvd., Tracy, San Joaquin County(RB#391041)
<br /> y 1. Distance to production wells for municipal, domestic, The report did not discuss production wells or other
<br /> agriculture, industry and other uses within 2000 feet of the site. potential sensitive receptors.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of Two 10,000-gallon aviation gasoline USTs,associated
<br /> any former and existing tank systems; excavation contours and piping,and a dispenser were removed 12/98. Soil
<br /> sample locations, boring and monitoring well elevation contamination was observed in 1998 from a leaking pipe
<br /> contours, gradients, and nearby surface waters, buildings, and dispenser, and confirmed in one piping sample.
<br /> streets, and subsurface utilities;
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of clay,silt,and sand. The total
<br /> diagrams; depth investigated was 30 feet due to drill rig refusal.
<br /> The consultant estimated the depth to wafer as of least
<br /> 70'
<br /> bc s.
<br /> R.
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal(quantity); The report stated 200 yards of excavated soil wasaerated in stockpiles and later returned to the USTs pit
<br /> per direction of CLty staff.
<br /> N: 5. Monitoring wells remaining on-site, fate; No monitoring wells were installed.
<br /> 6. Tabulated results of all groundwater ??epi to group wa erwas-nv a ermined.-Reg o�g dWater-flow—
<br /> direction was estimated as west and northwest.
<br /> elevations and depths to water, -
<br /> 7. Tabulated results of all sampling In 12/98, the confirmation soil sample maximum concentrations(20'from USTs at
<br /> i and analyses: 2'bgs) were TPHg, 370 mglkg;toluene, 5.9 mg/kg;ethylbenzene, 0.9 mg/kg;and
<br /> xylenes, 2.4 mg/kg. The after soil borings sample maximum concentrations in
<br /> FYI Detection limits for confirmation 10/08 were TPHd, 16 mg/kg(backfill in USTs pit at 10'bgs);and xylenes,
<br /> sampling 0.098 nig/kg(20'from USTs at 3'bgs). Groundwater was not sampled.
<br /> ❑N 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 described in the report.
<br /> I:. Y❑Lateral and l 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 An engineered remediation was not
<br /> system and the zone of capture attained for the soil and groundwater remediation required by the lead agency.
<br /> f
<br /> system;
<br /> Ik 10.Reports/information ❑Y Unauthorized Release Form 0 QMRs -
<br /> FY] Well and boring logs 0 PAR ❑N FRP FNJ Other
<br /> Y 1 11.Best Available Technology(BAT) usedor an explanation far not using Removal of USTs, aeration of excavated
<br /> BA T, soils before reuse as backfill in excavation,
<br /> and natural attenuation.
<br /> Y 12. Reasons why background wasfis unattaindWe rnor—residual soil co� nta`mina ion,remains onsite.
<br /> BAT;
<br /> N 13.Mass balance calculation of substance treated Initial mass and treated mass were not calculated by the consultant.
<br /> versus that remaining;
<br /> Y 14. Assumptions, parameters, calculations and After soil sample results show no Region 2 ESLs were exceeded.
<br /> i model used in risk assessments, and fate and
<br /> transport modeling;
<br /> Y 15. Rationale why conditions remaining at site will Soil contamination reportedly is limited in extent. Land use(City
<br /> not adversely impact waterquality, health, or other small aircraft airport) is not expected to change in the foreseeable
<br /> beneficial uses;and future.
<br /> By: JLB Comments Two 10,000-gallon aviation gasoline USTs, associated piping, and a dispenser were removed
<br /> t 12/98 from the subject site. Soil contamination was observed in 1998 from a leaking pipe arid dispenser, and
<br /> Date: confirmed in one piping sample. in.12/98, the confirmation soil sample maximum concentrations(20'from
<br /> 2/11/2009 USTs at 2'bgs) were TPHg, 370 mg/kg;toluene, 5.9 mg/kg;ethylbenzene, 0.9 mg/kg;and xylenes, .
<br /> 2.4 mg/kg. The after soil borings sample maximum concentrations in 10/08 were TPHd, 16 mg/kg(backfill in
<br /> F USTs pit at 90'bgs);and xylenes, 0,018 mg/kg(20'from USTs of 3'bgs). Groundwater was not sampled.
<br /> Minor residual soil contamination remains on-site. Based upon the limited extent.of contamination reported
<br /> in soil,no foreseeable changes in land use, and no ESLs exceeded, Regional Board staff concur with
<br /> San Joaquin County's Closure Recommendation.
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