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Case Closure Summary Page 2 <br /> Leaking Underground Fuel Storage Tank Program <br /> III Release and Site Characterization information (continued) <br /> FMaximum Documented Contaminant Concentrations -- Before and After Cleanup <br /> Contaminant Soil Before Soil Water Water Contaminant Soil Soil Water Water <br /> After Before After Before After Before After <br /> TPH(Gas) 11,000 ---- 12 0.21 MTBE 3.6 ---- 0.053 <0.0005 <br /> Benzene 0.24 ----: 0.82 0.004 Lead 330_ ---- ---- __.. <br /> Toluene 350 ---- 0.073 <0.0005 EDB - ND <0.0005 <br /> Ethyibenzene 160 1.3 0.0043 1,2-;DCA ---- -_-- 0.077 <0.0005 <br /> Xyfene 750 ---- 0.91 0.018 Oxygenates ---- ND 3. <0.0005 <br /> All results listed above are in parts per million (ppm) <br /> "Soil After"column was left unfilled because no remediation cleanup was ever implemented at the site. One soil sample at <br /> 1.5 feet bsg collected at the dispenser in 1987 during the tank removal had a concentration of 330 ppm of lead, the STLC <br /> for the sample was 6.9 ppm of lead. Soil samples from 15 feet and from the stockpile were significantly less at between <5 <br /> and 14 ppm STLC. <br /> "Water Before" results were from a combination of grab water samples from initial investigation in 1998, and samples from <br /> monitoring well##3 (the only consistently contaminated monitoring well) in 1999 and early 2000. Concentrations of the <br /> contamination in the monitoring wells have fallen significantly since then. "Water After"column reflects the latest quarterly <br /> monitoring results in 2002. <br /> MTBE was previously detected using Method 8020,but subsequent analysis by Method 8260 were either non-detect or in <br /> very low concentration (<5.0 µg11). Investigation showed minimal impact to soil and groundwater. Beneficial uses of <br /> groundwater are protected, now and in the future.. <br /> IV. Closure <br /> Does completed corrective action protect existing beneficial uses per the Regional Board Basin Plan? Yes <br /> Does completed corrective action protect potential beneficial uses per the Regional Board Basin Plan? Yes <br /> Does corrective action protect public health for current land use? Yes <br /> Site management requirements: none <br /> Should corrective action be reviewed if land use changes?Yes <br /> Monitoring wells decommissioned: NIA Number Decommissioned: 5 Number retained: 0 <br /> List enforcement actions taken: NOR sent <br /> List enforcement actions rescinded: None <br /> V. Local Agency Representative Data <br /> Name: Donna Heran Title: Director of Environmental Health <br /> Signature: �CqI4 �• Date: <br /> VI. Central Valley Regional Water Quality Control Board RB Notification <br /> Date Submitted to RB: Response Date: 01/21/2003 <br /> RB Staff: Jim Barton Response: Concurrence for Closure <br /> Title:Assoc Eng Geologist <br /> VII. Additional Comments, Data, etc. <br /> All remaining wells have been destroyed under EHD inspection. No further action is required for the site. <br /> This document and the related CASE CLOSURE LETTER, Shall be retained by the lead'agency as part of the . <br /> official site file. (08124193) Exhibit N Page 2 of 2- <br />