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ti (Owl'ABLE 1 -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: ARCO Station#2186,3212 N. California St., Stockton, San Joaquin County(RB#390805)
<br /> Y A 2005 sensitive receptor survey reported one municipal
<br /> 1. Distance to production wells for municipal, domestic,
<br /> supply well and 12 domestic wells within 2,000,of the
<br /> agriculture, industry and other uses within 2000 feet of the site. site. The nearest well is f,270'to the south. The wells are
<br /> not threatened by the USTs release.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of A site investigation in 8195 discovered a release to sot!
<br /> any former and existing tank systems, excavation contours and and groundwater. in 6/99, one 8,000-gallon gasoline and
<br /> sample locations, boring and monitoring well elevation two 10,000-gallon gasoline USTs and associated piping
<br /> contours, gradients, and nearby surface waters, buildings, were removed.
<br /> streets, and subsurface utilities;
<br /> Site lithology consists of clay,silt, and sand to 135, the
<br /> Y 3. Figures depicting lithology(cross section), treatment system total depth investigated.
<br /> diagrams,-
<br /> :YD
<br /> iagrams,}( 4. Stockpiled soil remaining on-site or off-site disposal (quantity); Approximately 990 tons of excavated soil was
<br /> transported to BFI Landfill in Livermore.
<br /> 7Nine(9)monitoring wells(MW-1D, MW-1R, MW-2, MW-3R,and MW-4 through
<br /> Y 5. Monitoring wells remaining on-site, fate; MW-8)and eight(8)remediation wells(VW-1A, VW-1B, VW-2A, VW-2B,
<br /> VW-3A, VW-3B, VW-4 and AW-1) will be property abandoned.
<br /> 6. Tabulated results of all groundwater Depth to groundwater varied from 33'bgs to 59'bgs. Groundwater
<br /> elevations and depths to water, gradient varied from 0.00'19 ft/ft to 0.04 ft/ft. Groundwater flow direction
<br /> varied clockwise from northeast to northwest.
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports, including closure report. .
<br /> and analyses:
<br /> Detection limits for confirmation -
<br /> sampling
<br /> QY Lead analyses
<br /> LyJ 8. Concentration contours of contaminants found and those remaining in soil and The extent of the identified
<br /> groundwater, and both ori-site and off-site: contamination is described in the
<br /> available reports.
<br /> Lateral and 0 Vertical extent of soil contamination
<br /> Lateral and El 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 Unauthorized Release Form FYI QMRs (60) 9195 to 12-10
<br /> F Well and boring logs PAR 10 FRP [5 Other Closure Report(5-11)
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not using USTs removal, over-excavation, SVE,and
<br /> BAT; I natural attenuation.
<br /> Y 12. Reasons why background waslis unattainable Minor residual soil and groundwater contamination remains on-site.
<br /> BA T,•
<br /> Y 13.Mass balance calculation of substance treated Consultant estimates 1,610 lbs of TPH removed by SVE.
<br /> versus that remaining, Approximately 712 lbs of TPHg remain in soil, and 0.06 lbs of TPHg
<br /> remain in groundwater.
<br /> Y 14. Assumptions,parameters, calculations and Consultant states no significant risk exists, as soil vapor and residual
<br /> model used in risk assessments, and fate and soil concentrations did not exceed Region 2 Environmental Screening
<br /> transport modeling; Levels for commercial use. The store building is approximately 80'
<br /> from the former USTs and is not threatened by soil vapor intrusion.
<br /> Y 15. 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 f future. TPN is estimated to reach WQGs in 2036.
<br /> By: JLComments:A site investigation in 8195 discovered a release to soil and groundwater. In 6/99, one 8,000-
<br /> —
<br /> gallon gasoline and two 10,000-gallon gasoline USTs and associated piping were removed at the subject
<br /> Date: site. Minor residual soil and groundwater contamination remains on-site. Based upon the limited extent of
<br /> 11/23/2011 contamination reported in soil and groundwater,a stable groundwater plume with declining concentrations,
<br /> no foreseeable changes in future land use(commercial), and minimal risks from soil, soil vapor,and
<br /> groundwater, Regional Board staff concur with San Joaquin County's Closure Recommendation.
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