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40, <br /> III Release and Site Characteriz-';on Information (continued) <br /> Maximum Documented Contaminant Concentrations--Before and After Cleanup <br /> = Contaminant F2,200' <br /> (ppm) Water (ppm) Contaminant Soil (ppm)After Water (ppm) <br /> ore After Before4 Afters Before Before° Afters <br /> TPH(Gas) 460 <0.05 <.05 Ethylbenzene <0.25 <2,500 <0.0003 <0.0003 <br /> TPH (Diesel) 12,0003 <0.05 <.05 Xylene 0.592 <2,5003 <0.00034 <0.0003 <br /> TPH(Motor Oil) 02 8,3003 <2.0 <2.0 <br /> Benzene <0.25' <2,5003 <0.0003 <0.0003 <br /> Toluene 1<0.25' <2,50031<0.0003 1<0.0003 1 MTBE I NA NA <br /> Comments: 'Sample from B2 at 25'collected on 5/10/95. 2Sample collected from B1 at 25'on 5/10/95. 3Sample collected <br /> from B4 at 15'on July 9, 1996. 4Groundwater sample collected from MW1 on 7/10/96. sGroundwater sample collected from <br /> MW1 on 3/12/97. <br /> The concentrations after are higher despite the excavation attempt in part because the sampling was more focussed in an <br /> effort to characterize the remaining contamination. The contamination appeared to have attenuated at depths of 23 feet. <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? No <br /> Monitoring/Vapor wells: 1 Number Decommissioned: 0 Number retained: <br /> List enforcement actions taken: Notice of Reimbursement sent 8/31/94 <br /> List enforcement actions rescinded: None <br /> V. Local Agency Representative Data <br /> Name: Donna Heran Title: Director of Environmental Health <br /> Signature: * ./ �C Date: r R <br /> 1 <br /> VI. Central Valley Regional Water Quality Control Board (RB) Notification <br /> Date Submitted to RB: Response Date: <br /> RB Staff: J. Brathovde Response: <br /> Title: Assoc Eng Geologist <br /> VII. Additional Comments, Data, etc. <br /> Registered Geologist William Millar#6175 with Cape Environmental stated that the clay barrier that is present between 30 <br /> and 35 feet with its low transmissivity may limit the vertical migration of petroleum hydrocarbons into existing groundwater. <br /> He estimated that there was two areas of remaining soil contamination, approximately 5.78 cubic yards under the building <br /> comprising 2.12 gallons of TEPH-diesel and 2.15 gallons of TEPH-motor oil and 2.67 cubic yards under the concrete <br /> electrical vault comprising 2.3 gallons of TEPH-diesel, 2.42 gallons of TEPH-motor oil and 0.08 gallons of total volatile <br /> hydrocarbons. <br /> This document and the related CASE CLOSURE LETTER,Shall be retained by the lead agency as part of the official <br /> site file. Case Closure Summary Page 2 of 2 <br />