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TA66E 1 - CHECKLIST OF REQUIRED DATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Keith's Chevron,25651 Highway 99 North,Acampo, San Joaquin County
<br /> Y 1.Distance to production wells for municipal, domestic, agriculture, No municipal supply wells and over 200 domestic
<br /> industry and other uses within 2000 feet of the site; wells are located within 2000 feet of the site. The
<br /> onsite supply well is 60 feet southwest(downgradient)
<br /> of the former USTs.
<br /> Y�
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank One 550-gallon heating oil and
<br /> systems, excavation contours and sample locations, boring and monitoring well elevation one 550-gallon waste oil;and one
<br /> contours, gradients, and nearby surface waters, buildings, streets, and subsurface 10,000-gallon, two 6,000-gallon,
<br /> utilities; and one 3,000-gallon gasoline
<br /> USTs were removed 8/53 and
<br /> 12/93,respectively.
<br /> 0 3.Figures depicting lithology(cross section), treatment system diagrams; Site litho/ogy consists of sand and silt The
<br /> total depth investigated was 79 feet
<br /> 0 4. Stockpiled soil disposed off-site(quantity); Approximately 800 cu.yds. of excavated soil was disposed offsite at
<br /> Forward Landfill,Manteca.
<br /> insftd for this
<br /> 5. Monitoring wells remaining on-site, fate; T 1 �thru�� �
<br /> will be abandoned.
<br /> Y� 6. Tabulated results of all groundwater elevations and depths to water, The depth to water varied from 73 to 79 feet
<br /> Groundwater flow direction varied from south to
<br /> southwest
<br /> F'71 7.Tabulated results of all sampling and In 12/93,maximum soil confirmation results were: TPHg(410 mg/kg),
<br /> analyses: benzene(0.17 mg/kg),toluene(6.7 mg/kg),sthy/benzene(6.9 mg/kg),and
<br /> Y Detection limits for confirmation sampling xylenes(46 mg/kg). Soil boring results for the monitoring wells in 5102
<br /> were all non-detect Groundwater results/n 7/02 were:MtBE(7 pg/L).
<br /> Lead analyses In 7/04,groundwater results were all non-detect
<br /> 0 8. Concentration contours of contaminants found and those remaining in soil
<br /> and groundwater, both on-site and off-site: The extent of contamination is defined by
<br /> 8 Lateral and Vertical extent of soil contamination soil borings and monitoring wells.
<br /> Lateral and Vertical extent of groundwater contamination
<br /> FRI 9.Zone of influence calculated and assumptions used for subsurface Based on the limited extent of
<br /> remediation system and the zone of capture attained for the soil and contamination,an engineered remedladon
<br /> groundwater remediation tem; system was not required at this site.
<br /> 0 10.Reports/information LJ Unauthorized Release Form 19 9 QMRs(6/02 to 7/04)
<br /> E] Boring logs El PAR a FRP F1 Other. Receptor Survey, and Closure Report
<br /> 0 11.Best Available Technology(BAT)used or an explanation for not using BAT,• Remove USTs, overexcavation and natural
<br /> attenuation.
<br /> r Minor soil and groundwater contamination remains on-site.
<br /> . koro
<br /> _. 1 Reawns why,bacun-dwos4, s--- _ --
<br /> unattainable using BAT,
<br /> FTJ 13.11 balance calculation of substance The consultant estimates 45 gallons of TPHg contamination remain in soil and
<br /> treated'versus that remaining; 0.00173 gallons of TPHg remain In groundwater.
<br /> 0 14.Assumptions, parameters, calculations and model A risk assessment was not required by San Joaquin County. The
<br /> used in risk assessments, and fate and transport
<br /> modeling;and Region 2 ESLs were not exceeded by remaining soil
<br /> concentrations.
<br /> 0 15. Rationale why conditions remaining at site will not Sol/contamination Is limited in extern,and based on 9 quarters of
<br /> adversely impact water quality, health, or other groundwater monitoring with concentrations declining to non-
<br /> beneficial uses. detect,contamination is not continuing to leach into groundwater.
<br /> By: Comments: One 550-gallon heating oil and one 550-gallon waste oil;and one 10,000-gallon, two 6,000-gallon,and one
<br /> n,B 3,000-gallon gasoline USTs were removed from the subject site 8/93 and 12/93, respectively. In 12193, maximum soil
<br /> confirmation results were: TPHg(410 mg/kg), benzene(0.17 mg/kg), toluene(6.7 mg/kg), ethylbenzene(6.9 mg/kg), and
<br /> Date: xylenes(46 mg/kg). Soil boring results for MW s in 5102 were all non-detect. Groundwater results in 7/02 were:MTBE(7
<br /> pg/L). In 7/04, groundwater results were all non-detect. The onsite supply well, sampled 10/03;was non-detect for
<br /> 6/23/05 Petroleum hydrocarbons. Based on the limited extent of soil contamination and decreasing contaminant concentrations in
<br /> groundwater, Regional Board staff concur with San Joaquin County's Closure Recommendation.
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