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<br /> ABLE 1 -CHECKLIST OF REQUIRED DATA
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<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES .
<br /> Site Name and Location: Stockton Terminal&Eastern RR, 1282 Shaw Road,Stockton, San Joaquin County(RB#391035)
<br /> Y 1. Distance to production wells for municipal, domestic, 14 private wells were reported within 2000'of the site.
<br /> agriculture, industry and other uses within 2000 feet of the site. The site supply well, 200' N of UST, tested•ND. The
<br /> nearest known down radient well is 1300'from the site.
<br /> Ir 12. Site maps, to scale, of area impacted showing locations of One 10,000-gallon diesel UST and associated piping were
<br /> any former and existing tank systems, excavation contours and removed 11/98. The UST was not leaking when removed;
<br /> sample locations, boring and monitoring well elevation however, .visual inspection revealed the piping was
<br /> contours, gradients, and nearby surface waters, buildings, leaking.
<br /> streets, and subsurface utilities;
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<br /> Y 3. Figures depicting lithology(cross section), treatment system Site lithology consists of silt and sand. The total depth
<br /> diagrams; investigated was approximately 72 feet.
<br /> Y 4. Stockpiled soil remaining on-site or off site disposal(quantity); approximately 28 cubic yards of over-excavated soil
<br /> was removed, tested and used as backfill in the UST I
<br /> excavation(Counly approved).
<br /> N 5. Monitoring wells remaining on-site, fate; No monitoring wells were required or installed for this investigation.
<br /> 8. Tabulated results of all groundwater Depth to groundwater was reported from approximately 38 feet(8/99,
<br /> elevations and depths'to wafer,• -possibly.perched)-to,60 feet_(1/08)_below_ground_surfece;(bgs).The
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<br /> reported regional groundwater flow direction is towards the south.
<br /> 7. Tabulated results of all sampling In 8/99, the before maximum soil boring results were TPHO, 9,100 mg/kg;and
<br /> and analyses: xylenes, 0.99 mg/kg. The after soil borings concentration in 1108 was TPHd,
<br /> 110 mg/kg. In 1/08, one grab groundwater sample result was TPHd, 150 ug/L.
<br /> Detection limits for confirmation
<br /> sampling
<br /> �Y Lead analyses
<br /> 8. Concentration contours of contaminants found and those remaining in soil and The extent of the identified
<br /> groundwater, and both on-site and off-site: contamination is described in applicable
<br /> reports.
<br /> Lateral and M Vertical extent of soil contamination
<br /> FNI Lateral and Vertical extent of groundwater contamination ,
<br /> 9. Zone of influence calculated and assumptions used for subsurface remediation An engineered remediation was not
<br /> system and the zone of capture attained for the soil and groundwater remediation required by the lead agency-
<br /> system,
<br /> gency.s stem;
<br /> 10.Reports/information ❑Y Unauthorized Release Foran FN QMRs
<br /> ❑Y Well and boring logs M PAR 0 FRP FY Other Sensitive Receptor Survey f
<br /> _Yj 11.Best Available Technology(BAT) used or an explanation for not using Removal of UST and piping, natural
<br /> BAT; attenuation.
<br /> _ Y;12. Reasons why background was<s unattainable Minor residual soil and.groundwater contamination remains on-site.
<br />,-_ BAT'--
<br /> Y 13.Mass balance calculation of substance Treated Initial mass was calculated as 16;000_Ibs:of TPHd_ sdil:Treated' -
<br /> mass was not calculated.
<br /> versus that remaining, li
<br /> 7Y 14. Assumptions, parameters, calculations and After soil sample results show TPHd Region 2 ESLs were slightly
<br /> model used in risk assessments, and fate and exceeded for gross contamination. WQGs were also slightly
<br /> transport modeling; exceeded for TPHd in groundwater. Neither presents a threat.
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<br /> 15. Rationale why conditions remaining at site will Soil contamination was limited in extent and estimated to decline to
<br /> not adversely impact water quality, health, or other ND within 18 years. Groundwater TPHd concentration will decline to
<br /> beneficial uses;and ND within a reasonable time frame. Rail yard land use is not expected
<br /> to change in the foreseeable future.
<br /> By: JLB Comments: One 10,000-gallon diesel UST and associated piping were removed 11/98. The UST was not
<br /> leaking when removed;however, visual inspection revealed the piping was leaking. Approximately 28 cubic
<br /> Date: yards of over-excavated soil was removed, tested and used as backfill in the UST excavation(County
<br /> 11/25/2008 approved). Minor residual soil and groundwater contamination remains on-site. Based upon the limited
<br /> extent of contamination present in soil, low level of TPHd detected in groundwater,and the lack of a threat to
<br /> from soil vapor intrusion in the rail yard, Regional Board staff concur with San Joaquin County's Closure
<br /> Recommendation.
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