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MLE 1 -CHECKLIST OF REQUIRED DA*
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: ARCO Service Station#760, 225 Cherokee Lane, Lodi,San Joaquin County, LUSTIS#390330
<br /> Case 2
<br /> Y 1. Distance to production wells for municipal, domestic, agriculture, One municipal supply well is located 812 feet east
<br /> industry and other uses within 2000 feet of the site; (cross-gradient) of the site.
<br /> y 2. Site maps, to scale, of area impacted showing locations of Four 10,000-gallon gasoline USTs were removed for
<br /> former and existing tank systems, excavation contours and Case#2 on 8/02. One 550-gallon waste oil tank was
<br /> sample locations, boring and monitoring well elevation contours, removed 9/88;two 6,000-gallon and one 8,000-gallon
<br /> gradients, and nearby surface waters, buildings, streets, and gasoline, one 550-gallon and one 400-gallon waste oil
<br /> subsurface utilities; tanks were removed between 6/91 and 7/91 for Case#1.
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of sand and silt. The total
<br /> diagrams; depth investigated was 105 feet.
<br /> Y 1 4. Stockpiled soil disposed off-site (quantity); Approximately 45 cu.yds. of excavated soil were disposed offsite at
<br /> Forward Landfill in Manteca.
<br /> Y 5. Monitoring wells remaining on-site, fate; Five monitoring wells(MW-1 through MW-5)installed for this investigation
<br /> will be abandoned.
<br /> Y 6. Tabulated results of all groundwater elevations and depths to The depth to water varied from 54 to 63 feet. Down-
<br /> water, gradient groundwater flow direction varied from
<br /> southeast to southwest.
<br /> y 7. Tabulated results of all sampling and In, maximum soil results were: TPHg(5,700 mg/kg)and TPHd
<br /> analyses: (4,380 mg/kg). In 8/02,maximum soil UST removal confirmation result
<br /> ❑y were: TPHg(400 mg/kg), ethylbenzene(1.2 mg/kg), and xylenes(3
<br /> Detection limits for confirmation sampling mg/kg). Maximum groundwater results in 10/02 were: TPHg(410 Pg/L),
<br /> ©Lead analyses benzene(3.2 pg/L), toluene(8.5 pg/L), ethylbenzene(6 Pg/L),xylenes(9.5
<br /> Pg/L), MtBE(3.7 pg/L),and 1,2-DCA (26 Pg/L). In 1/06, maximum
<br /> groundwater results were: TPHg(330 Pg/L), benzene, (0.82 Pg/L), toluene
<br /> (0.67 pg/L), ethylbenzene(0.63 pg/L),xylenes(18 pg/L), MtBE(4.5 Pg/L),
<br /> and 1,2-DCA 14 p
<br /> Y 8. concentration contours of contaminants found and those The extent of contamination was not defined by soil
<br /> remaining in soil and groundwater, both on-site and off-site: borings, grab groundwater samples, and
<br /> Y Lateral andY Vertical extent of soil contamination monitoring wells to the south and southeast
<br /> Lateral and Vertical extent of groundwater contamination (downgradient) of the Site.
<br /> _LJ 9. Zone of influence calculated and assumptions used for subsurface An engineered remediation system was not
<br /> remediation system and the zone of capture attained for the soil and required by SJCEHD for the current Case#2. SVE
<br /> groundwater remediation system; was required prior to Case#1 closure in 1997.
<br /> _Lj 10.Reports/information 1Y I Unauthorized Release Form y 15 QMRs (10/02 to 1/06)
<br /> Y❑ Boring logs El PAR Y❑ FRP Y❑ Other: Closure Report
<br /> 11.Best Available Technology(BAT)used or an explanation for not Remove USTs, over-excavation, SVE, and natural
<br /> usma BAT,' I attenuation.
<br /> y 12.Reasons why background wasps unattainable using BAT,' Soil and groundwater contamination remains on-site.
<br /> Y 13.Mass balance calculation of substance treated versus that In 1997, the consultant estimated 1,730 gallons of TPHg
<br /> remaining; and 1,390 gallons of TPHd contamination remain in soil at
<br /> the site. The estimate was not updated after 2002 removal.
<br /> yResidual soil concentrations in 2002 do not exceed Region 2
<br /> 14.Assumptions,parameters, calculations and model ESLs for commercial or industrial use. Groundwater exceeds
<br /> used in risk assessments, and fate and transport
<br /> modeling;and WQOs for TPHg,benzene,xylenes, and 1,2-DCA.
<br /> Y 15. Rationale why conditions remaining at site will not Soil contamination is limited in extent. Since 2002, 15 quarters of
<br /> adversely impact water quality, health, or other groundwater monitoring data do not show declining
<br /> beneficial uses. concentrations for TPHg in two of five wells(MW-2 and MW-3). .
<br /> By: Comments: Four 10,000-gallon gasoline USTs were removed for Case#2 on 8/02. One 550-gallon waste oil tank was
<br /> JLB removed 9/88;two 6,000-gallon and one 8,000-gallon gasoline, one 550-gallon and one 400-gallon waste oil tanks were
<br /> removed between 6/91 and 7/91 for Case#1. Active remediation included over-excavation and SVE. The Site is
<br /> a e: currently used as a paved used car lot in a commercial zone. Future land use will remain commercial. Based on the fact
<br /> that there are not decreasing concentrations in groundwater, Regional Board staff cannot concur with San Joaquin
<br /> 8/29/06 County's Closure Recommendation.
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