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Fi BLE 1 -CHECKLIST OF REQUIRED DATA J1
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES ;
<br /> Stockton, San Joaquin County(RB#8390428)
<br /> Site Name and Location: Former BP Oil Co. S5#?1191, 1469 Hammer Ln., ;
<br /> 1. Distance to production wells for municipal,domestic, agriculture, A 1993 sensitive receptor survey reported one water
<br /> y supply well(1,550 southeast))within 2,000 of the
<br /> industry and other uses within 2000 feet of the site: Site. The well!s not threatened b this release.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of any In 2-98, one 6,000-gallon gasoline, one 10,000-gallon
<br /> former and existing tank systems, excavation contours and sample gasoline,one 12,000-gallon gasoline,and one
<br /> locations, boring and monitoring well elevation contours, gradients, 6,000-gallon diesel USTs were removed.
<br /> and nearby surface waters, buildings, streets, and subsurface
<br /> utilities;
<br />. .� sists of clay;silt,and.sand to 114',
<br /> Site iithology con
<br /> Y 3. Figures depicting lithalogy{cross section), treatment system Site
<br /> total depth investigated.
<br /> dia rams;
<br /> Approximately 825 y of excavated soil was transported to
<br /> y 4. Stockpiled soil remaining on-site or off-site disposal Forward Landfill in Manteca.
<br /> (quantity);
<br /> y 5. Monitoring wells remaining on-site, fate; Seven(7)monitoring wells(MW-1 through MW-7).will be properly destroyed.
<br /> 4j. 6. Tabulated results of all groundwater Depth to groundwater varied from 46'bgs to 59'bgs. Groundwater flow direction
<br /> elevations and depthssu to water, varied from northwest to southeast at a gradient of 0.0005 ft/ft to 0.0008 ft/ft.,
<br /> 7. Tabulated results of all sampling All data adequately tabularized in various reports,including closure report. -
<br /> r`= —and`analyses:
<br /> 0 Detection limits for confirmation
<br /> sampling
<br /> Lead analyses
<br /> 8. Concentration contours of contaminants found and those remaining in soil and 7 The extent of the identified
<br /> groundwater,and both on-site and off-site: contamination is described in the
<br /> available reports:
<br /> OLateral and Vertical extent of soil contamination
<br /> Lateral and ElVertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Over-excavation was the engineered
<br /> system and the zone of capture attained for the soil and groundwater remediation remediation.
<br /> system; '
<br /> 10.Reports 1 information ❑Y Unauthorized Release Form FYIQMRs(34) 1102 to 6111
<br /> ❑y Well and baring logs Qy PAR FN� FRP Other Closure Report(12/11).
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not using USTs removal, over-excavation, and natural
<br /> BAT; attenuation.
<br /> Y 12. Reasons why background warms unattainable Residual soil and groundwater contamination remains on-site.
<br /> BA T,•
<br /> YD 13,Mass balance calculation of substance treated Consultant estimated approximately 9 lbs of TPHg remain in soil,
<br /> versus that remaining; k
<br /> 14.Assr�mpfi'ons,_parameters,_calculations_and� _Soil_vapor_was_not measured,_due to_the_active_servicetafion_a_n_d
<br /> w-- _Y__, ._ .-
<br /> model used in risk assessments, and fate and impacted soil distance to building(60). Soil results(TPHg)failed
<br /> transport modeling; ESLs for gross contamination and direct contact at 12'bgs.
<br /> Consultant states site does not represent a significant risk.
<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. Groundwater plume is stable and decreasing.Land use(commercial)
<br /> beneficial uses;and is not expected to change in the foreseeable future. TPN in
<br /> groundwater is estimated to reach WQGs in 18 years.
<br /> By: J Comments:In 2-98, one 6,000-gallon gasoline, one 10,000-gallon gasoline, one 12,000-gallon gasoline, and
<br /> one 6,000-gallon diesel USTs were removed at the subject site.Residual soil and groundwater contamination
<br /> Date: remains on-site. Based upon the limited extent of contamination reported in soil and groundwater,a stable
<br /> 6/11/2012 groundwater plume with declining concentrations, no foreseeable changes in future land use(commercial),
<br /> !. and minimal risks from soil vapor,soil and groundwater, Regional Board staff concur with San Joaquin
<br /> County's Closure Recommendation. -
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