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<br /> TAWA - CHECKLIST OF REQUIRED G -TA
<br /> FOR NO FURTHER ►ACTION REQUESTS AT UNDERGF AND TANK SITES
<br /> Site Name and Location: Reich's•Grocery, 7505 Linne Road,Tracy, San Joaquin County
<br /> Y I. Distance to production wells for municipal, domestic, agriculture, Four water supply wells were identified within 700 feet
<br /> ETT
<br /> industry and other uses within 2000 feet of the site; of the site. Sampling results of the three downgradient
<br /> wells were non-detect
<br /> ETwo 1,500-gallon gasoline
<br /> Y i12. Site maps, to scale, of area impacted showing locations of former and existing tank systems,
<br /> (:excavation contours and sample locations, boring and monitoring well elevation contours, USTs were removed in 9/93.
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<br /> bl
<br /> il
<br /> !' ae ngradients, and nearby surface wafers, buildings, streets, and subsurface utilities; Site maps are available l
<br /> the various reports.
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<br /> 0 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clay with sand and
<br /> gravel to 25 feet,sand and gravel to 40 feet, and
<br /> interbedded sand,silt and clay to 100 feet.
<br /> 4. Stockpiled soil disposed off-site (quantify); The disposition of excavated soils was not presented. The soil was
<br /> likely returned to the tank pit excavation.
<br /> ..5. Monitoring wells remaining on-site, fate; Six monitoring wells were installed for this investigation. The wells will be j
<br /> properly destroyed pending site closure.
<br /> The depth to water varied from 42 to 50 feet and
<br /> ��,� .,Tfi. Tabulated result�of a!!groundwater elevations and depths to wafer,'�,.the"gro m-dwaYer flow-dire-ction-is-to-the-northwest"--" —1
<br /> M 7. Tabulated results of all sampling and analyses: The maximum soil concentrations show TPHg at 48,300 mg/kg, and i
<br /> MtBE at 180 mg/kg. MtBE has been identified in groundwater at a {
<br /> 0 Detection limits for confirmation sampling maximum of 1,800 pg/1. Current monitoring shows the MtBE site 1
<br /> f Lead analyses maximum is 41 lig/l. Lead was identified at a maximum of 270 mg/kg in Il
<br /> soll at six feet below the former dispenser.
<br /> Ej `8. Concentration contours of contaminants found and those remaining in soil The extent of contamination is defined by
<br /> [And groundwater, both on-site and off-site: on-site soil borings and monitoring wells.
<br /> Y❑ Lateral and ❑Y Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> Y� k9. Zone of influence calculated and assumptions used for subsurface A SVE pilot test completed in October 1995
<br /> remediation system and the zone of capture attained for the soil and identirred a soil vapor ROI at 15 feet The
<br /> groundwater remediation.system, SVE system operated for approximately six
<br /> - months and removed 433 gallons of TPHg.
<br /> 10.Reports/information Y� Unauthorized Release Form Y� QMRs(3194 to 5102),
<br /> Y❑ Boring logs El PAR F] FRA F1 (CAP, 12/95 & Closure Summary Report, 9102)
<br /> Y 11.Best Available Technology(BA T) used or an explanation for not using BAT Remove USTs, SVE to reduce soil
<br /> Ij contamination, and natural attenuation.
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<br /> 12.Reasons why background was/is Shallow soil contamination remains on-site at the former UST areas, and MtBE 1
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<br /> unattainable using BAT contamination remains in groundwater downgradient of the former UST areas.
<br /> 13.Mass balance calculation of substance The consultant estimates that 430 gallons of TPHg was removed in six months
<br /> treated versus that remaining; of SVE, and conflirmation borings show a 46 to 95 percent reduction in mass.
<br /> Consultant states that less than one pound of MtBE remains in groundwater.
<br /> 0 ,14.Assumptions,parameters, calculations and mode!used in risk Results of fate and transport modeling predicted that
<br /> assessments, and fate and transport modeling; BTEX constituents would not impact groundwater at this
<br /> site. MTBE and lead calculations were not required.
<br /> Y�-j5. Rationale why conditions remaining of site will not adversely Groundwater monitoring and sampling documents
<br /> impact water quality, health, or other beneficial uses;and decreasing trends of MTBE. Groundwater will reach
<br /> Water Quali Objectives within a reasonable time.' y
<br /> By: fl� Comments: Reich's Grocery Store is located in a rural part of San Joaquin County south of Tracy. Two 1,500-gallon gasoline
<br /> MH USTs were removed from the site in September 1993, and fuel service is no longer available. Soil contamination was identified
<br /> r following UST removal, and a SVE system was operated at the site for approximately six months. The SVE system reportedly
<br /> removed 430 gallons of TPHg from site soils. Confirmation soil borings were completed in February 1999, and MtBE was
<br /> Date: identified in groundwater in the former tank pit area. Six monitoring wells were installed from August 1999 to June 2001,and
<br /> these wells have been monitored from four to eleven quarters. Decreasing trends of MtBE are shown in monitoring wells MW-1
<br /> 11/12/02 and MW-3,and the current sampling results(June 2002)show MtBE at 0.73 and 41 pgR, respectively. All other constituents are
<br /> non-detect. Three domestic wells were identified at 135 to 415 feet downgradient of the former UST site,and one school well was
<br /> identified at approximately 700 feet upgradient. All three domestic wells were sampled and found to be non-detect. The nearest
<br /> downgradient well at 135 feet northwest was destroyed in late 2000. The site is covered with asphalt and concrete, which should
<br /> limit leaching of contaminants to groundwater. Based on the decreasing trends of MtBE in groundwater and the delineation of the
<br /> �j groundwater plume, Board staff concur with San Joaquin County's closure recommendation. " {
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