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T/' E 1 - CHECKLIST OF REQUIRED DATF�
<br /> FOR NO FURTHEweACTION REQUESTS AT UNDERGROUhldfANK SITES
<br /> Site Name and Location Chevron#9-6171, 6633 Pacific Avenue, Stockton, San Joaquin County LUSTIS #390054
<br /> Y 1. Distance to production wells for municipal, domestic, Seventeen domestic wells and 15 municipal wells
<br /> agriculture, industry and other uses within 2000 feet of the site; (including 4 on the Lincoln Center) are located within
<br /> 2000 feet; no wells are clowngradient of the site.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of One 550-gallon waste oil UST and three unspecified
<br /> former and existing tank systems, excavation contours and volume gasoline USTs were removed 12-86. Two
<br /> sample locations, boring and monitoring well elevation contours, additional waste oil USTs were removed 12-97.
<br /> gradients, and nearby surface waters, buildings, streets, and
<br /> subsurface utilities;
<br /> Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of sand, silt, and clay. The
<br /> diagrams; total depth investigated was 90 feet.
<br /> 4. Stockpiled soil disposed off-site The consultant did not address the fate and amount of 1986 and 1997 soil
<br /> Nuantit excavated.
<br /> Y 5. Monitoring wells remaining on-site, Three monitoring wells were transferred to the dry cleaners investigation. Ten of
<br /> fate; thirteen monitoring wells installed for this investigation were abandoned
<br /> 28 August 2009.
<br /> Y 6. Tabulated results of all groundwater elevations The depth to water varied from 32 to 57 feet. The direction of
<br /> and depths to water. groundwater flow was towards the south.
<br /> Y 7.Tabulated results of all sampling and In 12/86, maximum soil confirmation results were TPHg, 84 mg/kg; and
<br /> analyses: benzene, 1.7 mg/kg; and in 1/98, maximum soil confirmation results were
<br /> HI
<br /> TPHd, 4,900 mg/kg; TPHmo, 7,400 mg/kg, and total BTEX, 8.4 mg/kg. In
<br /> Detection limits for confirmation sampling 6/01; maximum soil boring concentrations were xylenes, 0.018 mg/kg and
<br /> Lead analyses MTBE, 0.065 mg/kg. Maximum groundwater monitoring result in 12/93
<br /> were TPHg, 1,200 ug/L; and benzene, 850 ug/L. In 11/08, the maximum
<br /> groundwater result was MtBE, 14 /L.
<br /> Y 8. Concentration contours of contaminants found and those The extent of contamination was defined by soil
<br /> 9Yaining in sot d groundwater, both on-site and off-site: borings, and monitoring wells.
<br /> Lateral and Y Vertical extent of soil contamination
<br /> Lateral and Vertical extent of groundwater contamination
<br /> N 9. Zone of influence calculated and assumptions used for An engineered remediation system was not required
<br /> subsurface remediation system and the zone of capture attained by SJCEHD.
<br /> for the soil and groundwater remediation system;
<br /> Y 10.Reports/information F71 Unauthorized Release Form 74 QMRs (9/90 to 8/08)
<br /> El Boring logs Y❑ PAR El FRP N❑ Other: Closure Report,
<br /> Y 11.Best Available Technology(BAT) used or an explanation for Remove USTs and natural attenuation.
<br /> not using BAT;
<br /> Soil contamination remains on-site and leaching to
<br /> Y 12.Reasons why background was/is unattainable using
<br /> BAT; groundwater is still occurring, though at a much-reduced rate.
<br /> Y 13.Mass balance calculation of substance treated versus The consultant estimated remaining mass in soil as TPHg.
<br /> that remaining; 5.96 lbs. TPHd, 266 lbs. TPHmo, 401 lbs.; and remaining mass
<br /> in groundwater as MtBE, 4.5 x 10 lbs.
<br /> Y 14. Assumptions,parameters, calculations and The consultant compared the soil confirmation and groundwater
<br /> model used in risk assessments, and fate and results to Region 2 ESLs for vapor intrusion for residential use and
<br /> transport modeling;and passed.
<br /> Y 15. Rationale why conditions remaining at site will Soil contamination is limited in extent. Since 1990, 74 quarters of
<br /> not adversely impact water quality, health, or other groundwater monitoring data show a decline in concentrations for
<br /> beneficial uses. petroleum hydrocarbons, including MtBE.
<br /> By: Comments One 550-gallon waste oil UST and three unspecified volume gasoline USTs were removed 12-86. Two
<br /> JLB additional waste oil USTs were removed 12-97-No remediation was conducted at the site. The consultant compared the
<br /> soil confirmation and groundwater results to Region 2 ESLs for vapor intrusion for residential use and passed Since the
<br /> Lincoln Center is actively pumping groundwater and controlling the commingled plume, no wells are threatened by
<br /> Date: residual petroleum hydrocarbons. Land use as an active Chevron-branded service station is unlikely to change before
<br /> VVQGs are reached Therefore, Regional Board staff requests a No Further Action Required determination
<br /> 6/6/2009
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