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MLE 7 -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Unocal Service Station(Former Scotty's), 574 Grant Line Road, Tracy, San Joaquin County
<br /> (RB#390592)
<br /> y 1 1. Distance to production wells for municipal, domestic, A 2002 sensitive receptor survey reported two domestic,
<br /> agriculture, industry and other uses within 2000 feet of the site. two irrigation,and one municipal supply wells within
<br /> 2,000'of the site. The wells are either upgradient or
<br /> crossgradient of the USTs and are not threatened by the
<br /> USTs release.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of Three 8,000-gallon gasoline USTs were removed 12198.
<br /> any former and existing tank systems, excavation contours and
<br /> sample locations, boring and monitoring well elevation
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets, and subsurface utilities;
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of clay, silt, and sand to 70', the
<br /> diagrams; total depth investigated.
<br /> :YD 4. Stockpiled soil remaining on-site or off-site disposal (quantity); Approximately 300 tons of excavated soil was
<br /> transported to Forward Landfill in Manteca.
<br /> 7Y 5. Monitoring wells remaining on-site, fate; Six(6)monitoring wells(MW-1 through MW-6)and fourteen(14)remediation
<br /> wells(AS-1, EW-1, VE-1, VE-2, and OS-1 through OS-10) will be properly
<br /> abandoned.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 4'bgs to 8'bgs. Groundwater flow
<br /> elevations and de the to water direction varied from north to northwest
<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 /> EY 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
<br /> available reports.
<br /> Y❑Lateral and ElVertical extent of soil contamination
<br /> Lateral and ED Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Soil over-excavation and ozone sparging
<br /> system and the zone of capture attained for the soil and groundwater remediation of groundwater were the engineered
<br /> system; remediation.
<br /> 10.Reports/information 0 Unauthorized Release Form FYI QMRs 10-00 to 10-10
<br /> FY] Well and boring logs El PAR FY] FRP � Other Closure Report(3-11)and Addendum(8-11)
<br /> Y 11.Best Available Technology (BAT) used or an explanation for not using USTs removal, over-excavation, ozone
<br /> BAT; sparging, and natural attenuation.
<br /> Y 12. Reasons why background wasps unattainable Minor residual soil and groundwater contamination remains on-site.
<br /> BAT;
<br /> Y 13.Mass balance calculation of substance treated Consultant estimates 7,383.5 lbs of TPHg removed from soil, 2.4 lbs of
<br /> 7
<br /> versus that remaining,, TPHg remain in soil, and 7 lbs of TPHg remain in groundwater.
<br /> Y 14. Assumptions, parameters, calculations and Consultant states no significant risk exists, as soil concentrations did
<br /> 7
<br /> model used in risk assessments, and fate and not exceed Region 2 Environmental Screening Levels for commercial
<br /> transport modeling; use. The store building is approximately 30'from the former USTs
<br /> and is not threatened by soil vapor intrusion.
<br /> Y115. Rationale why conditions remaining at site will Soil and groundwater contamination reportedly are limited in extent.
<br /> not adversely impact water quality, health, or other Land use(commercial) is not expected to change in the foreseeable
<br /> beneficial uses; and future. MTBE estimated to reach WQGs in 2013.
<br /> By: JLB, Comments Three 8,000-gallon gasoline USTs were removed 12198 at the subject site. Minor residual UST soil
<br /> and groundwater contamination remains on-site. Based upon the limited extent of contamination reported in
<br /> Date: soil and groundwater, no foreseeable changes in future land use(commercial), and minimal risks from soil,
<br /> 9/8/2011 soil vapor, and groundwater, Regional Board staff concur with San Joaquin County's Closure
<br /> Recommendation.
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