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<br /> Ei BLE 1 -CHECKLIST OF REQUIRED DATA
<br /> `i FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
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<br /> Port W.of Stockton, 2201 Washington St., Stockton, San Joaquin County(RB#390997)
<br /> Site Name and Location7.
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<br /> y 1. Distance to production wells for municipal, domestic, A 2006 sensitive receptor survey reported no water
<br /> agriculture, industry and other uses within 2000 feet of the site. supply wells within 2,000'of the Site.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of any former - in 2-88, two 12,000-gallon gasoline USTs were
<br /> and existing tank systems, excavation contours and sample locations, removed.
<br /> tti boring and monitoring well elevation contours, gradients, and nearby
<br /> lt. surface waters, buildings, streets, and subsurface utilities;
<br /> Y 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clay,silt and sand to
<br /> i 49', the total depth investigated.
<br /> _Y1 4. Stockpiled soil remaining on-site or off-site Approximately 180 y of soil was removed down to 11'bgs. The fate it
<br /> disposal osal uanti ; of excavated soil was not discussed in the available reports.
<br /> y 5. Monitoring wells remaining on-site, fate; Ten(10)monitoring wells(MW3-1 through MW3-10)and three(3)remediation
<br /> wells OP-1 through OP-3 will be property destroyed.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 8'bgs to 13'bgs. Groundwater flow direction !
<br /> elevations and depths to water, varied from southwest to northeast at an average gradient of 0.004 ft/ft.
<br /> 7. Tabulated results of all sampling . _Al!daate
<br /> ta adequly tabularized in various reports,Including closure report.
<br /> and analyses: - - _ :_ -- y - . ..
<br /> 11 Y❑ Detection limits for confirmation
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<br /> sampling
<br /> l�❑Y Lead analyses
<br /> LyJ 8. Concentration contours of contaminants found and those remaining in The extent of the identified contamination is
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<br /> soil and groundwater, and both on-site and off-site: described in the available reports.
<br /> Y❑Lateral and Y❑Vertical extent of soil contamination
<br /> '�. Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface Over-excavation and ozone-hydrogen
<br /> !I remediation system and the zone of capture attained for the soil and peroxide(ISCO)injections were the
<br /> groundwater remediation system; I engineered remediation.
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<br /> 10.Reports I information 0 Unauthorized Release Form 0 QMRs(51) 7-99 to 10-11
<br /> EiRy Well and boring logs �y PAR �y FRP Other Ozone-Peroxide Injections Report(8-11), Closure
<br /> & ort 12-11
<br /> Y 11.Best Available Technology(BAT)used or an explanation USTs removal, over-excavation, ISCO injections, and -
<br /> for not usin BAT; natural attenuation.
<br /> Z12. Reasons why background wads unattainable Residual soil and groundwater contamination remains on-site.
<br /> g BAT,• ISCO injections released minimal TPH from clay,increasing
<br /> roundwater concentrations in one well(MW3-3). y 1
<br /> y. 13.Mass balance calculation of substance treated Consultant estimated TPH mass removed as 697 lbs in soil by over
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<br /> versus that remaining; excavation.Approximately 490 lbs TPH remain in soil and 0.73 lbs
<br /> I; TPH remain in groundwater.
<br /> Y 14. Assumptions,parameters, calculations and Soil vapor was not sampled since the nearest building is 75'from
<br /> model used in risk assessments, and fate and the known plume. Soil failed Region 2 ESL for TPHg gross
<br /> I� transport modeling; contamination and direct contact at 15'bgs, which is below typical
<br /> ii worker depth and below the water table. Consultant,states site does
<br /> not represent a significant risk.
<br /> Y 15. Rationale why conditions remaining at site will Soil and groundwater contamination reportedly are limited in ,
<br /> 11 not adversely impact water quality, health, or other extent Groundwater plume is stable and very slowly decreasing
<br /> beneficial uses;and due to TPH slowly desorbing in clay.Land use(commercial)is not
<br /> it expected to change in the foreseeable future. TPH in groundwater
<br /> ii is estimated to reach WQGs in 2112.
<br /> Byi JLBComments:in 2-88, two 12,000-gallon gasoline USTs were removed at the subject site. 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 very slowly declining concentrations, no foreseeable ,
<br /> 7/118/2012 changes in future!arid use(commercial),and minimal risks from soil vapor,soil and groundwater, Regional
<br /> ! Board staff concur with San Joaquin County's Closure Recommendation. .
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