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TABLE 1 - CHECKLIST OF REQUIRED DATA
<br />FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br />cation:
<br />Chevron Station #5-5775, 301 W. Kettleman Ln. Lodi, San Joaquin County (Lustis # 391019)
<br />rl.Distanceproduction wells for municipal, domestic, agriculture.
<br />A well survey in 1999 showed one municipal supply
<br />d other uses within 2000 feet of the site;
<br />(Well 12) and no private wells within 2000' of the
<br />site. Well 12 (200' southwest) has not shown
<br />Y
<br />Site maps, to scale, of area impacted showing locations of any
<br />impacts from petroleum hydrocarbons.
<br />Three 10,000 -gallon gasoline USTs, one 1,000
<br />former and existing tank systems, excavation contours and sample
<br />gallon and one 550 -gallon waste oil USTs and
<br />locations, boring and monitoring well elevation contours, gradients,
<br />associated piping were removed in 8/98.
<br />and nearby surface waters, buildings, streets, and subsurface
<br />utilities;
<br />Y
<br />3. Figures depicting lithology (cross section), treatment system diagrams:
<br />Site lithology consists of clay, silt, sand
<br />and gravel to 220 feet, the total depth
<br />investigated.
<br />4. Stockpiled soil remaining on-site or off-site disposal (quantit
<br />Approximately 108 cubic yards of over -excavated soil
<br />y);
<br />was disposed offsite at BFI, Livermore.
<br />Y
<br />5. Monitoring wells remaining on-site, fate;
<br />Twenty six monitoring wells (MW -1 through MW -19C), four SVE (VE -1
<br />through VE -4) and three extraction wells (EX -1 through EX -3) remaining on-
<br />site were properly abandoned on 9 April 2009.
<br />6. Tabulated results of all groundwater
<br />Depth to groundwater varied from 52 to 65 feet below ground surface
<br />elevations and depths to water;
<br />(bgs). The groundwater gradient varied from 0.004 to 0.01 f 1ft, and the
<br />downgradient direction varied from northeast to southwest.
<br />7. Tabulated results of all sampling and
<br />In 8/98, maximum soil concentrations were: TPHg, 2,300 mg/kg; benzene, 4.1
<br />analyses:
<br />mg/kg, ethylbenzene, 79 mg/kg; xylenes, 400 mg/kg, and MtBE; 330 mg/kg. No
<br />Fyj
<br />post -remediation soil samples were collected. Maximum groundwater
<br />Detection limits for confirmation monitoring concentrations in 1/999 and 3100 were: TPHg, 11,000 Ng/L; benzene,
<br />sampling 6,800 pg/L; EtBE, 2,400 pg/L; TAME, 780 pg/L; xylenes, 810 pg/L, and MtBE,
<br />❑Y Lead analyses 720,000 pg/L. In 1108, maximum groundwater concentration was: MtBE, 5 pg/L
<br />(EX -3).
<br />8. Concentration contours of contaminants found and those remaining in soil and The extent of contamination is
<br />ndwater, and both on-stiko-ond off-site: adequately defined by soil borings
<br />LYJ Lateral and Y 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 SVE and GWE, and natural
<br />system; attenuation. _
<br />10. Reports /information n Unauthorized Release Form D QMRs (35 from 1999— 2008)
<br />0 Well and boring logs Fy-� PARRY FRP ❑Y Other, Risk Assessments; Closure Summary Report
<br />Y J 11. Best Available Technology (BAT) used or an explanation for not using BAT; Removal of USTs, over excavation, SVE,
<br />GWE and natural attenuation.
<br />] 12. Reasons why background wasps unattainable using BAT; Limited soil contamination and groundwater pollution
<br />remains on-site.
<br />13. Mass balance calculation of substance treated versus that Mass treated (soil) was estimated as TPHg, 4,132 lbs.
<br />remaining; (136%); benzene, 85 Ibs.(133%); and MtBE, 443 lbs
<br />(1705,.1). Residual groundwater pollution was estimated
<br />as MtBE, 0.0074 lbs (0.1%).
<br />14. Assumptions, parameters, calculations and model used in Where Region 2 soil ESLs were exceeded, comparison
<br />risk assessments, and fate and transport modeling; to a Johnson Ettinger Model Tier 2 values did not
<br />exceed risk values. A fate and transport model
<br />predicted no impacts to sensitive receptors.
<br />J 15. Rationale why conditions remaining at site will not adversely Soil contamination is limited in extent. Results of 35
<br />impact water quality, health, or other beneficial uses; and quarters of groundwater monitoring show a decreasing
<br />trend in concentrations. WQGs have been reached.
<br />By: JLB . ` Comments: Three 10,000 -gallon gasoline USTs, one 1,000 gallon and one 550 -gallon waste oil USTs were
<br />removed from the subject site in 8198. GWE removed 99.9 % of contamination. A soil vapor intrusion risk
<br />Date: assessment showed threats from vapor intrusion are minimal. Fate and transport modeling showed no
<br />5/12/2009 sensitive receptors would be impacted by the MtBE plume. Based upon a stable plume 2 years after
<br />SVE/GWE stopped, 35 quarters of declining groundwater concentrations, acceptable risk from vapor
<br />intrusion, and the limited extent of contamination present in soil, Regional Board staff recommends closure
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