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TABLE 1 - CHECKLIST OF REQUIRED TA
<br /> ; FOR NO FURTHER ACTION:REQUESTS AT UNDERGROUND TANK SITES:
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<br /> Site Name and Location: Lagorio Ace Tomato, 5458 Section Road, Stockton, San Joaquin County
<br /> ETI 1. Distance to production wells for municipal, domestic, agriculture, Multiple agricultural and domestic wells exist within
<br /> industry and other uses within 2000 feet of the site; 200 feet of the site. The nearest well is approximately
<br /> ,! 90 feet southwest of the former UST area.
<br /> II Three 1,000 to 8,000-gallon
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems, gasoline and diesel USTs
<br /> excavation contours and sample locations, boring and monitoring well elevation contours, were removed in 12198.
<br /> gradients, and nearby surface waters, buildings, streets, and subsurface utilities;
<br /> 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of silt and silty sand to
<br /> ' 70 feet, the total depth investigated.
<br /> i Ninety cubic yards of impacted soil were excavated from the UST tank
<br /> 4. Stockpiled soil disposed off-site (quantity); pit and disposed at Forward Landfill in February 1999.
<br /> 5. Remedial wells remaining on-site, fate; One soil vapor extraction well remains on-site. The well will be properly
<br /> g destroyed pending site closure.
<br /> 6. Tabulated results of all groundwater elevations and depths to water, Groundwater was encountered at 70 feet and one
<br /> groundwater grab sample was collected.
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<br /> 7. Tabull ated results of all sampling and analyses: Following overexcavafion activities in February 1999, the maximum
<br /> FY i soil concentrations show MtBE at 14 mg/kg,and diesel at'62 mg/kg.
<br /> DetEction limits for confirmation sampling TPHg and BTEX constituents were non-detect. TPHmo was the only
<br /> Lead analyses constituent identified in groundwater at 70 feet, and MtBE was non-
<br /> detect at<1.0 ug/l. No indication of lead analysis.
<br />{ Soil contamination is defined b the five
<br /> FD8. Concentration contours of contaminants found and those remaining in soil y
<br /> and groundwater, both on-site and off-site: on-site soil borings. Only TPHmo was
<br /> Latera!and 9 Vertical extent of soil contamination identified in the one groundwater grab
<br /> ❑ Latera!andElVortical extent of groundwater contamination sample. Further delineation was not
<br /> required.
<br /> 9.Zone'of influence calculated and assumptions"used for subsurface An 8-hour SVE pilot test was completed in
<br /> Y remediation system and the zone of capture attained for the soil and March 2002. Low concentrations of TPHg,
<br /> ,a groundwater remediation system; xylenes, and MWE were identified in soil
<br /> vapor samples. A ROi was not determined.
<br /> 0 10.Repots/information 171 Unauthorized Release Form QMRs
<br /> Boring logs 0 PAR FRP Y❑ (Closure Summary Report, 9102)
<br /> 11.Best Available Technology(BAT)used or an explanation for not using BAT. Remove USTs and impacted sail, natural
<br /> attenuation.
<br /> - - contamination remains-on-site at;the.former USTarea.,-.The.romaining
<br /> 12.Reasons why background was/is
<br /> unattainable using BAT; contamination doss notpresent a significant threat to groundwatel-r—,.
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<br /> 13.Mass balance calculation of substance The consultant estimates that 1.25 pounds(0.2 gallons)of MtBE remains in
<br /> treated versus that remaining, site soils.
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<br /> 14.Assumptions,parameters, calculations and model used in risk A risk assessment was not required.
<br /> assessments, and fate and transport modeling;
<br /> E]Y 15. Rationale why conditions remaining at site will not adversely Impacted soil was identified to 40 feet; and groundwater
<br /> impact water quality, health, or other beneficial uses,and was not encountered until 70 feet. Soil contamination
<br /> ii will continue to degrade.
<br /> By: Comments: Three USTs(one 8,000-gallon gasoline; one 8,000-gallon diesel, and one 1,000-gallon unknown contents)
<br /> MH were removed from the site in December..1998. Tank pit soil samples confirmed contamination, and four soil borings were
<br /> completed. MtBE was identified in soil to,40 feet. One groundwater grab sample was collected at 70 feet, and only
<br /> Date: TPHmo was identified in groundwater. A SVE feasibility study was completed in March 2002, and low concentrations of
<br /> TPHg,xylenes, and MtBE were identified in soil vapor samples. Due to the low concentration of contaminants in soil
<br /> 1 I/19/02 vapor samples and the low estimate of MtBE in soil, the consultant concluded that SVE was pot a viable remedial option.
<br /> During installation of the SVE well, two soil samples were collected at 18 and 32 feet, and analyzed for MtBE using STLC
<br /> methods. MtBE was defected in these samples at 2.0 to 2.3 ugli, respectively. These leachate concentrations are below
<br /> water quality objectives. Based on the limited extent of soil contamination and the lack of groundwater impact, Board staff
<br /> concur with San Joaquin County's Closure Recommendation.
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