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TABLE I -CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Former Mobile Of/Corporation 1110-NPA,2375 Tracy Boulevard, Tracy,San Joaquin County
<br /> (RB#1390017)
<br /> 1. Distance to production wells for municipal,domestic, The 1986,2001,2005, and 2007 sensitive receptor
<br /> agriculture,industry and other uses within 2000 feet of the site. surveys reported two domestic, two ofIrrth sit and one
<br /> municipal supply wells within 2,000'of the site.None of
<br /> the wells are threatened b 'the release.
<br /> Ly -gallon Silo maps,to scale,or area impacted showing locations of Two 10,000-gallon and one 5,000•gallon gasoline USTs,
<br /> any former and existing tank systems, excavation contours and and one 280-gallon waste oil UST were removed 8186. The
<br /> sample locations, boring and monitoring well elevation product lines and dispensers were removed 6195.
<br /> contours, gradients, and nearby surface waters, buildings,
<br /> streets and subsurface utilities
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site!depth in consists of clay, silt,and sand to 45, the
<br /> diagrams: Iotal depth investigated
<br /> Approximately 600 y of excavated sell was
<br /> Y 4.Stockpiled soil remaining on-site or off-site disposal (quantity); transported In 1986 to 11689 Clover Rd.In Trac .
<br /> Y 5. Monitoring wells remaining on-site, fate; Fifteen(15)monitoring wells(AMW-1 through AMW-6,and MW 1 through
<br /> MW-9)will be propoLly abandoned.
<br /> 8. Tabulated results of all groundwater Depth to groundwater varied from 4'bgs to 8'bgs. Groundwater flow
<br /> , direction varied from north to northwest at a gradient varying from
<br /> elevations and depths to waterj
<br /> 0.004 ft/ft to 0.033 HIM
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports,Including closure report.
<br /> and analyses:
<br /> ❑Y Detection!!mils lorconfirmation
<br /> sampling
<br /> nY 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 /> FY11-ateral and OVerftal extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Over-excavation of soil,groundwater
<br /> system and the zone of capture attained for the soil and groundwater remediation pump and treatment,and batch
<br /> system; groundwater extraction wore the
<br /> engineered remediation.
<br /> 10.Reports 1 information 121 Unauthorized Release Form ❑V QMRs 4-90 to 4-11
<br /> FY] Well and boring logs' P PAR FRPEY10ther Closure Report(6-11)
<br /> Y 11.Best Available Technology(BAT)used or an explanation for not using UST removal, over-excavation,groundwater
<br /> BAT; pump and treat,batch groundwater
<br /> extraction, and natural attenuation.
<br /> yr 12. Reasons why background wasrs unattainable Minor residual soil and groundwater contamination remains on-site.
<br /> BAT,•
<br /> 713.Mess balance calculation of substance treated Consultant estimates 163 ibs of TPHg removed from groundwater by
<br /> versus that remaining; batch extraction.
<br /> FYI14. Assumptions,parameters, calculations and Pre-excavation soil concentrations did exceed Region 2
<br /> model used in risk assessments, and fate and Environmental Screening Levels for direct contact and gross
<br /> transport modeling; contamination. Confirmation soil samples were not taken. Consultant
<br /> states no significant risk exists after remediation. The store Is
<br /> approximately 30'from the former USTs and dispensers,and Is not
<br /> threatened bK soil va or intrusion.
<br /> 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 future. TPHq estimated to reach WQGs In 2048.
<br /> By: JLB� } Comments Two 10,000-gallon and one 5,000-gallon gasoline USTs,and one 280-gallon waste oil UST were
<br /> removed 8186. The product lines and dispensers were removed 6195 at the subject site.Minor residual soil
<br /> Date: and groundwater contamination remains on-site. Based upon the limited extent of contamination reported In
<br /> 5/8/2011 soil and groundwater,no foreseeable changes In future land use(commercial), and minimal risks from soil,
<br /> soil vapor,and groundwater,Regional Board staff concur with San Joaquin County's Closure
<br /> Recommendation. .
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