SITE INFORMATION AND CORRESPONDENCE

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r • �' 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 Before Soil Water Water After Contaminant Soil Soil Water Water After (ppm) After Before Before After Before(ppm) (Ppm) (Ppm) TPH(Gas) 4,000 ND<1.0 32 ND<0.050 MTBE ND<0.05 ND<0.05 ND<0.0025 ND<0.002 Benzene ND ND<0.005N 0.009 ND<0.0005 Methanol 250 ND<0.001 NA ND<1.0 Toluene 57 D<0.005 0.990 ND<0.0005 Ethanol NA ND<0.001 NA ND<0.500 Ethylbenzene 70 ND<0.005 0.630 ND<0.0005 Oxygenates NA ND<0.001 NA ND<0.002 Xylenes 430 ND<0.005 3.300 ND<0.0005 Lead 6.4 ND<0.150 ND<0.100 NA Soil Before results were from soil sample T-1 taken in the southeast corner of the excavation at 15 feet below surface grade (bsg)during the tank removal in September 1996. Soil Before results for MTBE and Methanol were from soil samples collected during installation of Monitoring Well MW-1 thru MW-3 in April 1999. The Soil After results were from soil samples corrected during installation of the monitoring well MW-4 in January 2002. Soil After result for lead was from April 1999. Water Before results were from grab water samples from boring B7 in May 1997. Water After results for all 5 oxygenates reflect the last four quarterly results (2003 to 2004). The detection limit of all oxygenates was 2 micrograms per liter, except TBA,which detection limit was 100 micrograms per liter. No remediation was conducted other than the removal of the excavated soil during the tank removal in September 1996. Beneficial uses of groundwater are protected, now and in the future. 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: none Should corrective action be reviewed if land use changes?Yes Monitoring wells decommissioned: Yes Number Decommissioned:4 Number retained: 0 List enforcement actions taken: NOR List enforcement actions rescinded: None V. Local Agency Representative Data Name: Donna Heran Title: Director of Environmental Health Signature: vy��ti --- Date: VI. Central Valley Regional Water Quality Control Board RB Notification Date Submitted to RB: September 23, 2004 Response Date: October 7, 2004 RB Staff: James L. L. Barton Response: Concurred with LOP final site closure status Title: Assoc Eng Geologist VII. Additional Comments, Data, etc. All monitoring wells related to this site have been destroyed by overdrilling or pressure grout under permit by Secorand C- 57 licensed holder Cascade on December 28, 2004. This document and the related CASE CLOSURE LETTER, shall be retained by the lead agency as part of the official site file. (08/24/93) Exhibit N Page 2 of 2