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<br /> pp3� TAB'�'� 1 - CHECKLIST OF REQUIRED TA
<br /> FORINO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
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<br /> Site Name and Locatiolr: Colberg Boat Works Inc., 848 Fremont Street, Stockton, San Joaquin County
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<br /> 1. Distance to production wells for municipal, domestic, agriculture, A well survey in 2001 shows the nearest agricultural
<br /> industry and other'uses within 2000 feet of the site; well is approximately 1320 feet to the southeast and
<br /> crossgradient of the site. No other wells were located
<br /> within 2000 feet of the site.
<br /> El2. Site maps, to scale, of area impacted showing locations of former and existing tank Two 550-gallon diesel, one
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation 8,000-gallon diesel,and one
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities; 1.000-gallon gasoline USTs
<br /> were removed in May 1986.
<br /> 3. Figures depicting lithology(cross section), treatment system:diagrams; Site lithology consists of silt, clay and sand to
<br /> 25 feet, the total depth investigated,'-with a
<br /> higher permeability zone between 22 and 25 ;
<br /> feet
<br /> NE 4. Stockpiled sail disposed off-site(quantity); Consultant reported the excavated soil was redistributed'across the site.
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<br /> F5. Monitoring wells remaining on-site, fate; f,
<br /> -Six-monitoring wells_.have b_Aen Installed for.this investigation._Th_e_wetls
<br /> (MW-1 through MW-6)will be properly destroyed pending site closure. i
<br /> 6. Tabulated results of all groundwater elevations and depths to water,' The depth to wafer varied from 5 to 25 feet,and the
<br /> groundwater Row direction varied from north to !;
<br /> northeast.
<br /> �yGroundwater monitoring results in 10/99 were 960 ug/L for TPHg, 240
<br /> 7.Tabulated results of al!sampling and analyses:
<br /> r�= pg/L for benzene,and 48 ug/L for MtBE. Groundwater monitoring
<br /> e Defection lirriits for confirmation samplingilo results in 4198 were 900 pg/L for TPHd. Lead in soil was 11 mg/kg in
<br /> Lead analyses 12/94. No other lead samples were taken. `
<br /> El8. Concentration contours of contaminants found and those remaining in soil
<br /> d groundwater,':l both on- and off-site: The extent of contamination is defined by
<br /> Y Cateral acrd is Y Vertical extent of soil contamination on-site soil borings and monitoring wells.
<br /> Lateral and. ;R k Vertical extent of groundwater contamination
<br /> W� 9. Zone of influence calculated and assumptions used for subsurface Based on the limited extent of soil
<br /> remediation syste;`L- 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.
<br /> 0 10.Reports/information Unauthorized Release Form Y❑ QMRs(7197 to 10199)
<br /> 19 Boring logs PAR FRP l (No Further Action Request Report, 6/01)
<br /> gy( p 9 Remove USTs, natural attenuation.
<br /> 11.Best Available Technology(BAT) used or an explanation for not using BAT; �
<br /> 12.Reasons why background wasrs .Decreasing concentrations have been attained at all monitoring'welis. Minor
<br /> unattainable using BAT, soil contamination remains on-site.
<br /> The consultant estimates that 0.57 gallons of TPHg remain in shallow soils,
<br /> Y� 13.Mass balance calculation substance and 0.031 gallons of TPHg remain in groundwater.
<br /> treated versus thaf,r'emalning;
<br /> 0 14.Assumptions,parameters, calculations and model used in risk
<br /> assessments, and fate and transport modeling;and A risk assessment was not required.
<br /> 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent and based on
<br /> impact water qualify; health, or other beneficial uses. nine sampling events, contamination is not continuing to
<br /> leach to groundwater. Groundwater monitoring shows a
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<br /> decreasing trend in concentrations.
<br /> By: Comments:!Two 550-gallon diesel, one 8,000-gallon diesel, and one 1,000-gallon gasoline USTs were removed from the
<br /> JLB subject site in May 1986. Soil contamination was identified at the diesel UST area and the gasoline USTarea. Multiple
<br /> borings and,six monitoring wells were completed to delineate and monitor contamination at this site.,Gasoline UST
<br /> Date: monitoring�wells MW-1 through MW-3 were sampled from 7197 to 9199. Diesel monitoring wells MW-4 through MW-6
<br /> were sampled from 7197 to 7198. Maximum groundwater contaminant concentrations declined in 9199 to 960 ug/L for
<br /> 1127/03 TPHg, 240g1L for benzene, and 48 pg/L for MtBE, and in 7198 to 900 pg1L for TPHd. Additional grab sampling in 1/02
<br /> showed the groundwater plume limited in extent to the former tank areas. Based on the minor soil contamination and
<br /> decreasing contaminant concentrations in groundwater, Board staff concur with San Joaquin County's Closure
<br /> Recommendation.
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