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<br /> TABU 1 - CHECKLIST OF REQUIRED UTA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: M& M Builders, 8111 Eleventh St, Tracy, San Joaquin County
<br /> 1. Distance to production wells for municipal, domestic, agriculture, Two domestic wells, located within 90 feet of the site,
<br /> industry and other uses within 2000 feet of the site; have been ND for petroleum hydrocarbons. {
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank One1,000-gallon diesel UST was
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation removed 8/88 and one 1,000-
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface gallon gasoline UST was removed
<br /> utilities; 6/94.
<br /> FT1 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of sand, silt and clay.
<br /> The total depth investigated was 46 feet.
<br /> FTI4. Stockpiled soil disposed off-site(quantity); The amount and fate of excavated soil is unknown.
<br /> Y� Three mom.torin 5. Monitoring wells remaining on-site, fate; 9 wells(MW-1 11.through MW-3)installed for this investigation,
<br /> will be abandoned. `
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<br /> Y 6. Tabulated results of all groundwater elevations and depths to water, The depth to water varied from 6 to 8 feet.
<br /> Groundwater flow direction was towards the north.
<br /> M 7.Tabulated results of all sampling and In 8/88 and 6/94, maximumisoil results were: TPHd(8,700 mg/kg),
<br /> analyses: benzene(0.08 mg/kg), toluene(1.4 mg/kg), and xylenes(1.1 mg/kg).
<br /> Y Detection limits for confirmation sampling Boring B-1 soil results in 3/;00 were TPHg(6.8 mg/kg), TPHd(310 mg/kg),
<br /> N andxylenes(1.1 mg/kg). Groundwater results in 9/2001 were TPHg
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<br /> Lead analyses (58 pg/L), TPHd(440 pg/L),'and xylenes(6 pg/L). In 12/04,groundwater
<br /> results were TPHd(130P1-17-1
<br /> 8. Concentration contours of contaminants found and those remaining in soil j
<br /> and groundwater, both on-site and off-site: The extent of contamination is defined by
<br /> Y Lateral and Y Vertical extent of soil contamination soil borings and monitoring wells. `
<br /> Latera/and ® Vertical extent of groundwater contamination .;
<br /> N� 9. Zone of influence calculated and assumptions used for subsurface Based on the limited extent of F
<br /> remediation system and the zone of capture attained for the soil and contamination, an engineered remediation
<br /> groundwater remediation s�stem; system was not required at this site. s
<br /> 0 10.Reports/information I__I Unauthorized Release Form El 10 QMRs(9/01 to 12/04)
<br /> Boring logs Y❑ PAR 0 FRP Y❑ Other: 0 Additional Site Investigation
<br /> 11.Best Available Technology(BAT) used or an explanation for not using BAT,' Remove USTs and natural attenuation.
<br /> Y❑ 12.Reasons why background walls Minor soil and groundwater contamination remains on-site.
<br /> unattainable using BAT,, it
<br /> Y The consultant estimates 0.0005 t8
<br /> 13.Mass balance calculation of substance F gallons of TPHg and 0.004 gal/ons of TPHd
<br /> treated versus that remaining; contamination remain in groundwater. y..
<br /> ❑ 14.Assumptions, parameters, calculations and model it
<br /> used in risk assessments, and fate and transport A risk assessment was not required by the San Joaquin County
<br /> modeling;and Environmental Health Department. In 2000, with the exception of
<br /> TPHd(310 mg/kg),soil contaminant concentrations were below
<br /> QY Region 2 Soil Screening Levels.
<br /> 15. Rationale why conditions remaining at site will not Soil contamination is limited in extent, and based on 10 quarters
<br /> adversely impact water quality, health, or other of groundwater monitoring, the TPHd plume is stable in the f
<br /> beneficial uses. source area, while minor TPHd contamination is continuing to
<br /> leach into groundwdter.
<br /> By: Comments: One 1,000-gallon diesel UST was removed 8/88 and one 1,000-gallon gasoline UST was removed 6/94 from
<br /> JLS the subject site. In 8/88 and 6/94, maximum soil results were: TPHd(8,700 mg/kg), benzene(0.08 mg/kg), toluene
<br /> (1.4 mg/kg), and xylenes(1.1 mg/kg). Boring 8-1 soil results in 3/00 were TPHg(6.8 mg/kg), TPHd(3 10 mg/kg), and
<br /> Date: xylenes(1.1 mg/kg). Groundwater results in 9/2001 were TPHg(58 pg/L), TPHd(440 pg/L), and xylenes(6 Pg/L).
<br /> In 12/04, groundwater results were TPHd(130 pg/L). Based on the limited extent of soil contamination, a stable TPHd
<br /> plume located in the source area, lack of impacts to two nearby domestic wells after neady 20 years, and sporadic TPHd
<br /> 5/6/OS groundwater contaminant concentrations less than one order of magnitude in excess of water quality objectives, Regional
<br /> Board staff concur with San Joaquin County's Closure Recommendation.`
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