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a Case Closure Summary Page 2 ' t <br /> t..;zaking Underground Fuel Storage Tank Fwwgram <br /> ill Release and Site Characterization Information (continued) <br /> EMXiamum 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 /> pb) <br /> (p (ppm) (ppb) <br /> ' <br /> TPH (Gas) 1,200 1,30D 96,800 ND<50 MTBE ---- --+ ND<5.0 ND<0.5D <br /> Motor Oil ---- ---- ---- ---- Lead 4 --- <br /> Benzene 1.1 4.1 400 ND<0.50 EDB ---- ---- ---- ND<0.50 <br /> Toluene 5.0 1.2 550 ND<0.50 1,2-DCA ---- - ---- ND<0.50 <br /> 622 ND<0.50 Oxygenates <br /> ---- ---- ND<5.0 ND<0.50 <br /> Ety! <br /> h benzene <br /> 1.3 8.4 yJ <br /> 000 ND<0.50 <br /> 31 2 <br /> Xylene 3.0 , <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 sack 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 /> F <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 /> If <br /> j Monitoring wells decommissioned: No Number Decommissioned: 0 Number retained: 5 <br /> E <br /> List enforcement actions taken: NOR sent <br /> i List enforcement actions rescinded: None <br /> V. Local Agency Representative Data <br /> i Name: Margaret LagorioTitle: Supervising REHS/Site Mitigation/LOP Unit IV <br /> Signature: Date: <br /> t . <br /> VI. Central Valley Regional Water Quality Control Board (RB) Notification <br /> Date Submitted to RB: September 30, 2002 Response Date: <br /> RB Staff: Marty Hartzell Response: <br /> r. Title: Assoc Eng Geologist <br /> VII. Additional Comments, Data, etc. <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 />