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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: ARCO Station#5469, 130S. Wilson Way, Stockton, San Joaquin County(RB#391072)
<br /> Y f 1. Distance to production wells for municipal, domestic, Sensitive receptor surveys(2001 &2007)reported four
<br /> agriculture, industry and other uses within 2000 feet of the site: municipal supply wells(700'south to 1,400'south'east)
<br /> and one industrial supply,well(1,800'northeast)within
<br /> 2,000'of the site. The wells are not threatened by the
<br /> USTs release.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of Site dispensers and product lines were replaced 3199.
<br /> any former and existing tank systems, excavation contours and
<br /> sample locations, boring and monitoring well elevation
<br /> contours, gradients, a'nd nearby surface waters, buildings,
<br /> streets, and subsurface utilities;
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of beds of caliche(Ca CO3),:'clay,
<br /> diagrams; silt, and sand to 150', the total depth investigated.
<br /> Y 4. Stockpiled soil remaining on-site or off-site disposal (quantity);, Approximately 6 cubic yards of excavated soil was
<br /> y)'
<br /> transported to BFI Landfill in Livermore.
<br /> :YD 5. Monitoring wells remaining on-site, fate; Thirteen(13)monitoring wells(MW-1 through MW-13)and five(5)
<br /> remediation wells 1W:1 through IW-5 will be Broperly abandoned.
<br /> G. Tabulated results of ail groundwater Depth to groundwater varied from 36'bgs to 44,bgs. Groundwater flow
<br /> :ielevatons and de-ths towter, ~ =direction-varied#rom--ast-t"or.thwesa
<br /> - —,
<br /> LYJ 7. Tabulated results of al!sampling All data adequately tabularized in,various reports,including closure report.
<br /> and analyses:
<br /> Detection limits for confirmation
<br /> sampling
<br /> �Y Lead analyses
<br /> MY 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- i
<br /> available reports.
<br /> Y❑Lateral and y❑Vertical extent of soil contamination
<br /> Lateral and FlVertical 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 1 information ❑Y Unauthorized Release Form ❑Y QMRs(41) 6-00 to 11-10
<br /> s
<br /> Well and boring logs 0 PAR FRP Other Site Conceptual Model (3-07), Closure Report
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not using Dispensers and piping removal, over-
<br /> BAT, excavation, ozone sparging, and natural
<br /> attenuation.
<br /> x _Y 12. Reasons why background waslis unattainable Minor residual soil and groundwater contamination remains on-site.
<br /> BAT,-` -- — _ -
<br /> :YD 13.Mass balance calculation of substance treated Consultant estimates 2.7 lbs of TPHg remain in soil, and 0.8 ibs of .
<br /> TPHg remain in groundwater.
<br /> versus that remaining;
<br /> 7Y 14. Assumptions, parameters, calculations and Consultant states no significant risk exists, as residual soil
<br /> mode!used in risk assessments, and fate and concentrations:did not exceed Region 2 Environmental Screening
<br /> transport modeling; Levels forcommercial use. The store building is approximately 50'to
<br /> 80'from the former dispensers and is not threatened by soil vapor
<br /> intrusion.11
<br /> Y 15. Rationale why conditions remaining at site will Soil and groundwater contamination reportedly are limited in extent.
<br /> s 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 is estimated to reach WQGs in 2021.
<br /> By: JLB Comments Site dispensers and product lines were replaced 3199 at the subject site. Minor residual soil and
<br /> groundwater contamination remains on-site. Based upon the limited extent of contamination reported;'in soil
<br /> Date: and groundwater, a stable groundwater plume with and declining concentrations, no foreseeable changes in
<br /> 11/14/2011 future land use(commercial), and minimal risks from soil, soil vapor,and groundwater, Regional Boaid staff
<br /> concur with San Joaquin Coun 's,Closure Recommendation.
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