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Q. -TABLE 1 -CHECKLIST'OF REQUIRED DA
<br /> FOR NO FURTHER ACTION"REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Union Ice,425-North Union Street, Stockton,San Joaquin County
<br /> ,1. Distance to production wells for municipal, domestic, agriculture, industry The site map shows 18 water wells within 2,000
<br /> 'and other uses within 2000 feet of the site, feet of the site. The closest well appears to be
<br /> approximately 400 feet north of the site.
<br /> InS!E Ej
<br /> Site maps, to scale, of area impacted showing locations of former and existing tank systems, (two
<br /> 10,000-gallon
<br /> four ne, o
<br /> =; (two 10,000-gallon gasoline,one
<br /> !excavation co.0ntours and sample locations, boring and monitoring well elevation contours, 500-gallon gasollne%il/diesel,
<br /> :gradients, and nearby surface wafers, buildings,streets, and subsurface ufi!!tles; and one 250-gallon waste oil)
<br /> j and theproducf pipelines were
<br /> removed from the site.
<br /> '3. Figures depicting!lthology(cross section), treatment system diagrams;
<br /> No treatment system was used. Site lithologyis
<br /> depicted in the geologic cross sections and well
<br /> ii boring logs.
<br /> Y4. Stockpiled soil remaining on-site or off site disposal(quantity); Approximately 1,800 cubic yards of impacted soil was disposed
<br /> of off-site. ``
<br /> a f
<br /> �' Five monitoring wells were installed. San Joaquin County has proposed
<br /> 5. Monitoring wells remaining on-site, fate decommissioning4hese:weNs pending the-f2egional:Board's:concurrence with,the-
<br /> s closure recommendation. r
<br /> 0 6. Tabulated results of all groundwater n.
<br /> elevations and depths to water, " Groundwater elevations varies between 37 and 62 feet yy
<br /> bgs,with a northeasterly flow directioI'
<br /> l
<br /> 1
<br /> .Tabulated results of alt sampling and analyses: TPH-oil of 12,000 mg/kg and TPHg at less than 400 mg/kg were detected in soil
<br /> FYI �7
<br /> {, beneath the 500-gallon and the 250-gallon tanks,respectively. TPHd at
<br /> Detection limits for confirmation sampling 78 mg/kg'also was detected in soil from the pipeline area. The areas under the
<br /> Lead analyses 500-gallon and the 250-gallon tanks were over-excavated. Five monitoring wells
<br /> were installed.Latest monitoring data(September 1998)shows MtBE at
<br /> 0.70 ug/1 in water samples from well MW-1 and 0.51 ug/l from MW-5. All other f
<br /> constituents were below detectable limits.
<br /> ❑y r, Concentration contours of contaminants found and those remaining in soil
<br /> 8.and groundwater, and both on-site and off-site:
<br /> Lateral and Vertical extent of soil contamination
<br /> Lateral and [vi Vertical extent of groundwater contamination
<br /> 9.Zone of influence calculated and assumptions used for subsurface No subsurface remediation system was used at
<br /> remediation system and the zone of capture attained for the soil and this site. The limits of the soil excavation are
<br /> I• depicted on the site map'.
<br /> E-groundwater remediation system;
<br /> ] 10.Reports/information Unauthorized Release Form i;�MRs(Dates)June 1992—September 1998 7
<br /> 0 Well and boring logs EIPAR 0.FRP Other(report name)June 25, 1999 Closure Request
<br /> ^ M•�11.`Besf Available Technology{BAT}used or an explanation for of using AT The leak sources(tanks)were removed from the
<br /> site. .
<br /> E: -
<br /> 12.Reasons why background wasris unattainable using BAT, Remaining hydrocarbons require time to naturally attenuate.
<br /> r
<br /> '" An estimated 4,808 pounds of contaminants were
<br /> 13.Mass balance calculation of substance treated versus that remaining; removed from the soil;378 pounds remain.
<br /> 14.Assumptions,parameters;calculations and model used in risk
<br /> assessments, and fate and transport modeling;
<br /> EKI15.Rationale why conditions remaining at site will not adversely The.remaining hydrocarbons should naturally degrade over
<br /> impact water quality, health, or other beneficial uses;and time.
<br /> N0 ,1
<br /> 16.WET or TCLP results
<br /> By: Comments: In 1989,elevated levels of TPH(mostly oil and grease)were detected beneath the 500-gallon and 250-gallon tanks. 7
<br /> -b The areas under these tanks were over-excavated, removim
<br /> ng approxiately 1,800 cubic yards of impacted soil.:Confirmation
<br /> Date: sampling shows residual contamination remaining in the.over-excavated sideways. From 1992 to 1993,.five groundwater monitoring
<br /> wells were installed. Low concentrations of contaminants were detected in water samples throughout the monitoring period, which
<br /> (e was terminated in September 1998. The latest monitoring data only show WE contamination in wells MW-1 at 0.70,ugl and MW-5 at 0.51 pg/1. A site map shows 18 water wells in the area;however,San Joaquin County indicates that no drinking wells are
<br /> affected by conditions at the site. Based on extensive over-excavation and the remaining minor contamination,staff concurs with
<br /> San Joaquin Countv closure recommendation.
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