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TABL64 - CHECKLIST OF REQUIRED D"
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
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<br /> Site Name and Location: Smith Canal Pump Station, 2144 Fontana Avenue, Stockton,San Joaquin County
<br /> A sensitive receptor survey in 1999 reported three
<br /> Y 1. Distance to production wells for municipal, domestic, agriculture, private wells 1000 feet north,northwest and west of
<br /> industry and other uses within 2000 feet of the site; the site. An onsite irrigation well was abandoned 1/92.
<br /> Upgradient Smith Canal is 100 feet south.
<br /> ❑ One 5,000-gallon diesel UST
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank was punctured during upgrade
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation in 10/87, resulting in a 1,100
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface utilities; gallon spill. The UST was
<br /> patched 11/87 and removed
<br /> 2/92. Free product was
<br /> observed in the tank pit.
<br /> ETI
<br /> Site lithology consists of pea gravel fill,sand,
<br /> 3. Figures depicting lithology(cross section), treatment system diagrams; silt and clay. The total depth investigated was
<br /> 36 feet.
<br /> FE 4. Stockpiled soil disposed off-site (quantity); An unspecified amount of soil was excavated and removed offsite.
<br /> 0- 5 Seven monitoring wells(MW-1 to MW-7), installed for this investigation,will
<br /> Y_ _. Monitoringavel/s.[emaining.on-site„fate;,.
<br /> be propefly adandoned:""”"
<br /> 6. Tabulated results of all groundwater elevations and depths to water; The depth to water varied form 7 to 14 feet. The
<br /> groundwater flow direction varied from north to
<br /> northwest.
<br /> 7. Tabulated results of all sampling and analyses: Maximum soil boring results in 1989 reported TPHd(1,680 mg/kg),
<br /> ethylbenzene(0.23 mg/kg), and xylenes(0.65 mg/kg). In 9/99,
<br /> 8 Detection limits for confirmation sampling additional soil analyses reported TPHd(61 mg/kg). Groundwater
<br /> Y Lead analyses maximum sample from 10/89 reported TPHd(4,000 pg/L), toluene(15
<br /> pg/L), ethylbenzene(13 pg/L),and xylenes(80 pg/L).;In 12/03,'.
<br /> groundwater samples reported TPHd(85 pg/L). .:
<br /> 8. Concentration contours of contaminants found and those remaining in soil The extent of contamination is defined by
<br /> and groundwater, both on-site and off-site: soil borings and groundwater monitoring
<br /> Lateral and Vertical extent of soil contamination wells.
<br /> Lateral and Vertical extent of groundwater contamination
<br /> 0 9.Zone of influence calculated and assumptions used for subsurface Based on the limited extent of soil and
<br /> remediation system and the zone of capture attained for the soil and groundwater contamination,an engineered
<br /> groundwater remediation system; remediation system was'not required at
<br /> this site.
<br /> 0 10.Reports/information y❑ Unauthorized Release Form QMRs, 11/89 to 10/03
<br /> I Y� Boring logs Y❑ PAR 0 FRP Other CAP(3/94), Pump Test(9/00), Closure Report(4/01)
<br /> 111.Best Available Technology(BAT) used or an explanation for not using BAT, Remove UST and natural attenuation.
<br /> v 12.Reasons why background waslis^="` — `
<br /> unattainable using BAT, Minor soil and groundwater contamination remains on-site."
<br /> �. N� 13.Mass balance calculation of substance Mass balance was not estimated.
<br /> treated versus that remaining;
<br /> 0 14.Assumptions,parameters, calculations and model used in risk A risk assessment was not required.
<br /> assessments, and fate and transport modeling;and
<br /> i FE 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent, and based on 38
<br /> impact water quality, health, or other beneficial uses. quarterly sampling events, contamination is not
<br /> continuing to leach to groundwater. Groundwater
<br /> monitoring shows a decreasing trend in concentrations.
<br /> By: Comments: One 5,000-gallon diesel]UST was damaged in 10/87,patched in 11/87, and removed from the subject site in
<br /> ng 2/92. Multiple borings and monitoring wells were completed from 1989 to 2002, to delineate contamination at this site.
<br /> Maximum soil boring results in 1989 reported TPHd(1,680 mg/kg), ethylbenzene (0.23 mg/kg), and xylenes(0.65 mg/kg).
<br /> 3 Date: /n 9/99, additional soil analyses reported TPHd(61 mg/kg). Groundwater maximum sample from 10/89 reported TPHd
<br /> (4,000 pg/L), toluene(15 pg/L), ethylbenzene (13 pg/L), and xylenes(80 pg/L). In 12/03, groundwater samples reported
<br /> 3/2/04 TPHd(85 pg/L). Free product was bailed from MW-4 from 1989(1.5 feet)to 1999(sheen). Based on the limited extent of
<br /> soil and groundwater contamination and twelve quarters of groundwater analysis, which show a decreasing trend in
<br /> concentrations, Board staff concur with San Joaquin County's Closure Recommendation.
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