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TABLE 1 - CHECKLIST OF REQUIRED DATA f
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SiTES
<br /> Site Name and Location: Charlie's Day and Night Lock Service, 706 N. Eldorado Street, Stockton, San Joaquin County
<br /> 1. Distance to production wells for municipal, domestic, agriculture, A well survey in 2001 showed three municipal wells
<br /> industry and other uses within 2000 feet of the site; located approximately 500 to 1800 feet crossgradlent
<br /> of the site. All municipal wells have been closed. Two
<br /> domestic wells located 2,000 feet crossgradient One
<br /> domestic well is located 1,700 feet upgradient.
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank Two 4,000 gallon gasoline USTs i
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation were removed in June 1997. }
<br /> contours,gradients, and nearby surface waters, buildings, streets, and subsurface utilities, Piping was removed in August
<br /> 1998.
<br /> 3. Figures depicting litholo Site lithology consists of silt and clay, with
<br /> g p g gy(cross section), treatment system diagrams; r
<br /> discontinuous lenses of sand to 60 feet the total
<br /> depth investigated.
<br /> 4. Stockpiled soil disposed off-site (quahtity); Consultant reported the excavated soil was redistributed onto adjacent
<br /> lot east of site.
<br /> 5. Monitoring wells remaining on-site, fate; Five monitoring wells have been installed for this investigation..,The wells k
<br /> (MW-1 through MW-5)will be properly destroyed pending site closure. }
<br />.,� water varied from 21 to 24 feet;and "" ` ` }
<br /> 6. Tabulated results of all groundwater elevations and depths to water, The depth to
<br /> - ,
<br /> the groundwater flow direction varied from north to '
<br /> northeast �
<br /> 0 7.Tabulated results of all sampling and analyses: Groundwater monitoring results in 5102 were 230 ug/L for3TPHg,'4 Ng/L
<br /> Y Detection limits for confirmation sampling for benzene,and 2.1 pg/L for MtBE. Groundwater monitoring results in
<br /> 8102 were 0.77 pg/L for 1,2-DCA. Lead in soil at 1.5 feet below fuel
<br /> Lead analyses dispenser was 330 mg/kg. No other lead samples were taken.
<br /> 0 8. Concentration contours of contaminants found and those remaining in soil The extent of contamination is def=ined by
<br /> and groundwater, both on-site and off-site: on-site soil borings and monitoring wells.
<br /> Lateral and Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 0 9.Zone of influence calculated and assumptions used for subsurface Based on the limited extent of soil
<br /> remediation system and the zone of capture attained for the soil and contamination,an engineered remediation
<br /> groundwater remediation system; system was not required at this site.; ,.
<br /> 10.Reports/information E] Unauthorized Release Form QMRs(10/97 to 10199) r
<br /> 0 Boring logs 0 PAR N❑ FRP Y❑ (Additional Site Assessment Report, 3102)
<br /> 11.Best Available Technology(BAT) used or an explanation for not using BAT, Remove USTs, natural attenuation.
<br /> "y� 12.Reasons why background waslis Decreasing concentrations have been attained at all monitoring wells. Minor
<br /> unattainable using BAT,• soil contamination remains on-site.
<br /> EyD13.Mass balance calculation of substance An estimate of contaminant mass was not required, due to declining
<br /> L' -treated versus thatremaining; ___. o'ancentration-trends-in-groundwater
<br /> f
<br /> 0 14.Assumptions,parameters, calculations and model used in risk
<br /> assessments, and fate and transport modeling;and A risk assessment was not required.
<br /> r
<br /> 0 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent, and based on
<br /> impact water quality, health, or other beneficial uses. twelve sampling events, contamination is not continuing
<br /> to leach to groundwater. Groundwater monitoring
<br /> shows a decreasing trend in concentrations.
<br /> By: Comments: Two 4,000-gallon gasoline USTs were removed from the subject site in June 1997. Piping and a dispenser
<br /> JLB island were removed in August 1,998. Soil contamination was identified at the UST area and dispenser island. Multiple
<br /> borings and five monitoring wells were completed to delineate and monitor contamination at this site. Additional borings
<br /> Date: and grab sampling was completed in 2002. Monitoring well maximum groundwater concentrations declined to 230 ug/L
<br /> for TPHg, 4 pg1L for benzene, and 2.1 ug1L for MtBE in 2002- 1,2-DCA was identified only once in 2002 at a
<br /> 1/21103 concentration slightly above water quality objectives. Based on the limited extent of soil contamination and�decreasing
<br /> contaminant concentrations in groundwater, Board staff concur with San Joaquin County's Closure Recommendation.
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