SITE INFORMATION AND CORRESPONDENCE

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Case Closure Summary Page 2 Leaking Underground Fuel Storage Tank Program III Release and Site Characterization Information (continued) Maximum Documented Contaminant Concentrations - - Before and After Cleanup Contaminant Soil (ppm) Water (ppm) Contaminant Soil (ppm) Water (ppm) Before After Before After Before After Before After TPH (Gas) 140 140 2.7 <0.050 Xylene 0.04 0.04 0.034 <0.0005 TPH (Diesel) NA 3000 0.081 0.051 Ethylbenzene 0.02 0.02 0.0218 <0.0005 Benzene 0.01 0.01 0.0045 <0.0005 Oil 8 Grease NA NA NA NA Toluene 0.04 0.04 0.0021 <0.0005 Heavy Metals NA NA NA NA MTBE 11.7 1.7 77.0 1.0061 Comments: The before soil concentrations are from boring SB 10-2 at 11 feet on 817189, except MTBE which is from CPT1 at 20 feet in 12101. The after soil concentrations are the same as the before since the areas did not have soil remediation, except the TPN-diesel result which is from D2 collected 3 feet below a dispenser in 3104. The laboratory noted the diesel result does not meet the laboratory standard for diesel. Previous TPH concentrations not matching the laboratory standard were identified as Stoddard solvent or paint thinner. The before and after groundwater concentrations are from MW-1A the most contaminated, down-gradient data point. Neither 1,2 DCA nor EDB have been detected In scil or groundwater samples analyzed. 400 cubic yards of soil were excavated and 206,500 gallons of water were extracted during interim remediation at this site. Groundwater contaminant concentrations have declined over time. Compliance with the Public Participation requirements in Section 2728 of the California Code of Regulations has been met. IV. Closure Does completed corrective action protect existing beneficial uses per the Regional Board Basin Plan? Yes Does completed corrective action protect potential beneficial uses per the Regional Board Basin Plan? Yes Does corrective action protect public health for current land use? Yes Site management requirements: NA Should corrective action be reviewed if land use changes? Yes Monitoring/Vapor wells decommissioned: Yes Number Decommissioned: 3 Number retained: 3 List enforcement actions taken: NOR sent to RP List enforcement actions rescinded: NA It V. Local Agency Representative Data Name: Margaret Lagorio Title: Program Coordinator Unit IV, REHS Signature: Date: VI. Central Valley Regional Water Quality Control Board RB Notification Date Submitted to RB: Response Date: RB Staff: J. Barton Response: Title: Eng. Geologist VII. Additional Comments, Data, etc. This document and the related CASE CLOSURE LETTER, Shall be retained by the lead agency as part of the official site file.