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<br /> TABLE 1 - CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Elkhorn Country Club, 1050 Elkhorn Drive, Stockton, San Joaquin County
<br /> 1. Distance to production wells for municipal, domestic, agriculture, Three water supply wells are located within 2,000 feet I
<br /> industry and other uses within 2000 feet of the site; g of the site,and a small man-made pond is 50 feet !
<br /> upgradient of the former UST area. i
<br /> One 1,000-gallon gasoline I
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems,El UST was removed in 5/91. I
<br /> excavation contours and sample locations, boring and monitoring well elevation contours, Site maps are provided.
<br /> gradients, and nearby surface waters, buildings,streets, and subsurface utilities;
<br /> Boring logs and cross-sections show sand with
<br /> Y� 3. Figures depicting lithology(cross section), treatment system diagrams; sandy silt to silty clay to 35 feet.
<br /> F4. Stockpiled soil disposed off-site (quantity); Excavated soils were returned to the tank pit excavation. k
<br /> 5. Monitoring wells remaining on-site, fate; Six monitoring wells and eight combination SVE/AS wells currently exist
<br /> �Y on-site. The wells will be properly destroyed following site closure.
<br /> �Y 6. Tabulated results of all groundwater elevations and depths to water; Groundwater levels varied from 6 to 37 feet below
<br /> g ground surface, and flow is to the northeast. ;
<br /> �Y 7.Tabulated results of all sampling and analyses., Maximum groundwater monitoring results for April 2001 in.pg/1 show
<br /> TPHg at 570, toluene at 0.66,and xylenes at 15. Benzene, ethyl
<br /> Detection limits for confirmation sampling benzene, MtBE, and other oxygenates were non-detect at appropriate
<br /> Lead analyses detection limits. Lead was non-detect in soil at<5 mg/kg during UST
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<br /> removal activities in May 1991.
<br /> 8. Concentration contours of contaminants found and those remaining in soil The lateral and vertical extent of soil and
<br /> and groundwater, and both on-site and off-site: groundwater contamination has been
<br /> © Lateral and Y❑ Vertical extent of soil contamination
<br /> defined.
<br /> Lateral and Vertical extent of groundwater contamination
<br /> A combination SVE/AS remediation system
<br /> y� 9. Zone of influence calculated and assumptions used r the soil and operated from 8/99 to 9/00. Consultant
<br /> remediation system and the zone of capture attained for the soil and estimates that 134 gallons of gasoline was
<br /> groundwater remediation system; .removed from site soils.
<br /> 0 10.Reports/information Unauthorized Release Form Y❑ QMRs(3rd Qtr 1995 to 2o°Qtr 2001)
<br /> Y❑ Boring logs 171 PAR �. FRP Other(Closure Summary Report, 2/01)
<br /> 11.Best Available Technology(BAT) used or an explanation for not using BAT; Removed USTs. SVE/AS utilized to remove
<br /> 95% of contaminants.
<br /> Y 12.Reasons why background wasrs Minor contamination remains in shallow soil and groundwater near the former
<br /> unattainable using BAT; UST and dispenser. The groundwater contamination is limited in extent, and
<br /> remaining concentrations do not present a significant threat to water quality.
<br /> Further remediation is not cost effective.
<br /> Y� 13.Mass balance calculation of substance The consultant estimates the initial mass was approximately 238 pounds of
<br /> treated versus that remaining; TPHg, and the remaining mass determined from confirmation borings is
<br /> approximately 11 pounds, a 95 percent reduction.
<br /> Based on the limited extent of groundwater
<br /> 14.Assumptions, parameters, calculations and model used in risk contamination, a risk assessment was not required.
<br /> assessments,and fate and transport modeling,
<br /> YJ15. Rationale why conditions remaining at site wilt not adversely Remaining contamination is limited in extent.
<br /> impact water quality, health, or other beneficial uses;and Contamination will naturally degrade.
<br /> By: Comments: One 1,000-gallon gasoline UST was removed from the site in May 1991. Contamination was identified during
<br /> 7 assessment activities, and multiple soil borings and monitoring wells were installed. A SVE/AS system was operated on
<br /> the site from August 1999 to September 2000, and quarterly monitoring reports document the reduction in groundwater
<br /> contamination. MtBE was identified in a water sample from one monitoring well at a maximum of 98 pgAin February 1998,
<br /> Date: but has been non-detect at<5.0 pg/1 in all wells since April 1999. All other fuel oxygenates and fuel additives are non-
<br /> detect at appropriate detection limits. Two municipal wells are 1,000 and 1,250 feet northwest of the site, and an on-site
<br /> ��3,lC irrgation well is 1,000 feet east of the site. All three wells are cross gradient to the former UST site. Based on the
<br /> investigation and remediation completed to;date, Board staff concur with San Joaquin County's closure recommendation.
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