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s <br /> Case Closure Summary Page 2 <br /> krtmg Underground Fuel Storage Tank Prom <br /> III Release and Site Characterization Information (continued) <br /> Maximum Documented Contaminant Concentrations -- Before and After Cleanup <br /> Contaminant Soil Before Soil Water Water Contaminant Soil Soil Water Water <br /> (ppm) After Before After Before After Before After <br /> (ppb) (ppm) (ppb) <br /> TPH (Gas) 1,200 1,300 96,800 N13<50 MTBE ---- ---- ND<5.0 ND<0.50 ` <br /> Motor Oil ---- ---- ---- ---- Lead 4 ---- ---- ---- <br /> Benzene 1.1 4.1 400 N13<0.50 EDB ---- ---- ---- ND<0.50 <br /> Toluene 5.0 1.2 550 ND<0.50 1,2-DCA ---- ---- ---- ND<0.50 <br /> Ethylbenzene 1.3 8.4 622 ND<0.50 Oxygenates ---- ---- ND<5.0 ND<0.50 ' <br /> Xylene 3.0 31 2,000 ND<0.50 a <br /> Soil Before results are from sample MW2-2. Soil After results are from sample MW5-3. Water Before results are from <br /> MW2 prior to March 1995. Water After results are from MW2 on 5129102. In December 1994, about 108 yards of the <br /> contaminated soil was overexcavated from the original tank pit. Oxygen Release Compound (ORC) in a sock was placed in <br /> MW-2 from March 1999 to September 1999. Contamination in the soil is limited to about 20' bsg in the area of MW-2/MW- <br /> 5 based on soil and groundwater investigation. Total mass remaining in the soil was calculated as 19 kilograms of TPH-gas, <br /> in a volume of 23 cubic yards. Groundwater samples from 5 monitoring wells steadily declined to non-detect level. <br /> Investigation showed minimal impact to soil and groundwater. No drinking water receptor wells within 2000 feet of the area, <br /> but multiple monitoring wells of 3 LOP sites within 2000 feet. Beneficial uses of groundwater are protected, now and in the <br /> 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: Yes 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 List enforcement actions rescinded: None 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: Don Heran Title: Director of Environmental Health <br /> Signature: d-M� - Date: j--7—o3 <br /> VI. Central Valley Regional Water Quality Control Board (RB) Notification <br /> Date Submitted to RB: September 30, 2002 Response Date: October 31, 2002 <br /> RB Staff: Marty Hartzell Response: No Further Action Required Occurrence <br /> Title: Assoc Eng Geologist <br /> VII, Additional Comments, Data, etc. <br /> t <br /> All five monitoring wells on and off sites were destroyed by overdrilling (MW2,'5) and pressure grouting (MW1,3,4)on <br /> January 6, 2003. <br /> This document and the related CAST` 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 />