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TABrt 1 - CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: PG&E,4040 West Lane,Stockton,San Joaquin County
<br /> 1. Distance to production wells for municipal, domestic, agriculture, Due to the fact that this was a contaminated soils-only,
<br /> industry and other uses within 2000 feet of the site; a site sensitive receptor survey was not required.
<br /> y� 2. Site maps, to scale, of area impacted showing locations of former and existing tank In 10103,soil contamination was
<br /> systems, excavation contours and sample locations, boring and monitoring well reported under the waste oil tank
<br /> elevation contours, gradients, and nearby surface waters, buildings, streets, and (WOT)piping after removal,and
<br /> subsurface utilities; beneath one gasoline dispenser
<br /> and one diesel dispenser during
<br /> three dispenser pan upgrades.
<br /> Y� 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clayey sand to 9.5 feet,
<br /> the total depth investigated.
<br /> ED 4. Stockpiled soil disposed off-site(quantity); The amount of soil removed during the waste oil tank piping removal
<br /> and dispenser pans upgrade was not reported.
<br /> 0 5. Monitoring wells remaining on-site, fate; Monitoring wells were not required or installed. - -
<br /> FNI 6. Tabulated results of all groundwater elevations and depths to water; Groundwater was not encountered during the sod-
<br /> only investigation. The estimated depth to water
<br /> was 20 to 30 feet
<br /> FY 1 7.Tabulated results of all sampling and analyses: Maximum analytical results of confirmation soil samples collected
<br /> were:for one waste oil tank piping removal, tetrachloroethylene,
<br /> eDetection limits for confirmation sampling 0.0079 mg/kg;and for two of three dispenser pan upgrades soil
<br /> Y Lead analyses samples, TPHd, 140 mg/kg, TPHg, 2.4 mg/kg,and MtBE, 1.5 mg/kg.
<br /> in 3104,soil investigation sample analyses, taken at 5, 7, and 9 feet
<br /> below ground surface(bgs)at each location,reported ND.
<br /> ED 8. Concentration contours of contaminants found and those remaining in soil
<br /> and groundwater, both on-site and off-site: The confirmation soil samples and on-site
<br /> satl borings define the extent of soil
<br /> Y Lateral and Y Vertical extent of soil contamination Lateral and ® Vertical extent of groundwater contaminationPTI contamination.
<br /> R
<br /> 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.
<br /> 0 10.Reports/information Yl Unauthorized Release Form N❑ QMRs
<br /> 0 Boring logs El PAR El FRP 0 Other Soil Report
<br /> 0 11.Best Available Technology(BAT) used or an explanation for not using BAT,'
<br /> Soil excavation and natural attenuation.
<br /> 0 12.Reasons why background wasps
<br /> unattainable using BAT, Minor soil contamination remains on-site.
<br /> El13.Mass balance calculation of substance
<br /> treated versus that remaining; Mass balance was not calculated for soil.
<br /> ❑ 14.Assumptions,parameters, calculations and model used in risk
<br /> assessments, and fate and transport modeling;and A risk assessment was not required.
<br /> TJ 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent
<br /> impact water quality, health, or other beneficial uses.
<br /> By: Comments: In October 2003 after dispenser pan upgrades and WOT piping replacement,confirmation soil
<br /> JLB sample analyses reported contamination in soil at the site. Maximum analytical results of confirmation soil
<br /> samples collected for the WOT piping removal were:tetrachloroethylene, 0.0079 mg/kg,while soil samples
<br /> Date: collected for two of three dispenser pan upgrades were: TPHd, 140 mg/kg, TPHg, 2.4 mg/kg,and MtBE,
<br /> 7/27/04 1.5 mg/kg. Subsequently in 3104,a soil investigation determined that the depth of the soil contamination did
<br /> not exceed 5 feet. Soil sample analyses, taken at 5, 7,and 9 feet bgs at all three locations,reported ND.
<br /> Groundwater was estimated between 20 and 30 feet below ground surface. Based on the limited extent of the
<br /> remaining soil contamination, Regional Board staff concur with San Joaquin County's Closure
<br /> Recommendation.
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