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TAkt 1 - CHECKLIST OF REQUIRED IUATA
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Granite Construction, 10500 Harlan Drive,French Camp,San Joaquin County(Lustis#390733)
<br /> Y 1. Distance to production wells for municipal, domestic, agriculture, A well survey in 1999 showed no municipal
<br /> industry and other uses within 2000 feet of the site; supply and 33 private wells within 2000'of the
<br /> site.
<br /> Y 2. Site maps, to scale, of area impacted showing locations of any former One 12,000-gallon and one 20,000-gallon diesel
<br /> and existing tank systems, excavation contours and sample locations, USTs, two 10,000-gallon gasoline USTs,and
<br /> boring and monitoring well elevation contours, one 500-gallon waste oil UST were removed in
<br /> gradients, and nearby surface waters, buildings, streets, and 4192.
<br /> subsurface utilities;
<br /> Y1 3. Figures depicting lithology(cross section), treatment system diagrams; Site lithology consists of clay,silt and
<br /> sand to 40 feet, the total depth
<br /> investigated.
<br /> Y1 4. Stockpiled soil remaining on-site or off-site disposal(quantity); Approximately 700 cu.yds. of over-excavated soil,
<br /> removed from the dispenser area, was reused onsite.
<br /> Y 5. Monitoring wells remaining on-site, fate; Eight monitoring wells(MW-1 through MW-8) remaining on-site will be
<br /> ro Earlyabandoned.
<br /> Yj6. Tabulated results of all groundwater Depth to groundwater varied from 15 to 30 feet below ground surface
<br /> elevations and depths to water, (bgs). The groundwater gradient varied from 0.001 to 0.004 ft/ft,and the
<br /> downgradient direction varied from northeast to southwest.
<br /> 7. Tabulated results of all sampling and In 4192,maximum soil concentrations were: TPHg, 5,900 mg/kg; TPHd,
<br /> analyses: 15,000 mg/kg;benzene, 70 mg/kg, toluene; 630 mg/kg,ethylbenzene; 190 mg/kg,
<br /> ❑Y and xylenes;1,000 mg/kg. In 3193, maximum soil boring concentrations were:
<br /> Detection limits for confirmation TPHg, 0.67 mg/kg;benzene,0.042 mg/kg, toluene;0.017 mg/kg,and xylenes;
<br /> sampling 0.068 mg/kg. Maximum groundwater concentrations in 5195 were: TPHg,
<br /> 2,600 pg/L;benzene, 790 pg/L toluene, 150,Ug/L;ethylbenzene, 361rg/L;and
<br /> ❑Y Lead analyses xylenes,330 pg/L. In 10104,maximum groundwater concentrations were: TPHd,
<br /> 120 pg/L;and benzene, 1.2 pg/L(MW-2).
<br /> Lyj 8. Concentration contours of contaminants found and those remaining in soil and The extent of contamination is
<br /> ndwater, and both on-sitend off-site: adequately defined by soil borings
<br /> Lyj Lateral and 1Y I Vertical extent of soil contamination and monitoring wells.
<br /> ©Lateral and ©Vertical extent of groundwater contamination
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation Remove USTs, overexcavation,
<br /> system and the zone of capture attained for the soil and groundwater remediation and natural attenuation.
<br /> s stem;
<br /> 10.Reports/information ❑Y Unauthorized Release Form FY QMRs(17 from 1993—2004)
<br /> QY Well and boring logs 10 PAR ❑N FRP FY] Other;Closure Summary Reports
<br /> Y 11.Best Available Technology(BAT) used or an explanation for not using BAT,' Removal of USTs and natural attenuation.
<br /> Y 12.Reasons why background wasrs unattainable using BAT; Limited soil contamination and groundwater pollution
<br /> remains on-site.
<br /> -- 13.Mass balance calculation of substance treated versus that An engineered remediation was not required. Residual
<br /> remaining; soil contamination was estimated in gallons as: TPHg,
<br /> 4; TPHd, 23;benzene,0.09;toluene,0.05;ethylbenzene,
<br /> 0.03;and xylenes, 0.08. Residual groundwater pollution
<br /> was estimated in gallons as: TPHg, 13; TPHd, 4;
<br /> benzene,0.18;toluene, 0.09;ethylbenzene, 0.08;and
<br /> x lenes, 0.1.
<br /> Y 14. Assumptions,parameters, calculations and model used in Region 2 soil ESLs were not exceeded. TPHd and
<br /> risk assessments, and fate and transport modeling; benzene exceeded Water Quality Goals.
<br /> Y 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent. Results of 17
<br /> impact water quality, health, or other beneficial uses;and quarters of groundwater monitoring show a decreasing
<br /> trend in concentrations. WQGs may be reached in 1
<br /> year.
<br /> By: JLB Comments:One 12,000-gallon and one 20,000-gallon diesel USTs, two 10,000-gallon gasoline USTs, and one 500-
<br /> gallon waste oil UST were removed in 4/92. Site is a large fenced gravel quarry so threats from vapor intrusion are
<br /> Date: 4/13/06 minimal. An onsite well was abandoned in 2004. Based upon 17 quarters of declining groundwater concentrations,
<br /> and the limited extent of contamination present in soil, Regional Board staff concur with San Joaquin County's
<br /> Closure Recommendation.
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