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Case Closure Summary Page 2 <br /> Leaking Underground fuel Storage Tank Program <br /> 3 <br /> III Release and Site Characterization Information (continued) <br /> f <br /> Maximum Documented Contaminant Concentrations -Before and After Cleanup (tank removal) <br /> Contaminant Soil Soil Water Water Contaminant Soil Soil Water Water <br /> 'iBefore After Before After, Before After Before After <br /> (in Ppm) (in ppm) (in ppm) (in ppm) <br /> TPH(Gas) 2,200 5.2 13 .960 MTBE _048 <br /> TPH (Diesel) 640 6.8 - .900 EDB 0.34 - -- <br /> Benzene 960 0.031 .290 .240 Lead <br /> Toluene 2,000 0.014 .087 .130 ---- <br /> Ethylbenzene 4,700 0.96 <.005 .090 <br /> Xylene ---- 1.1 .550 .140 <br /> "Soil Before" results are from soil samples taken at the tank removal in 1986 except TPH—d which is from P4 on <br /> 12112194. "Soil After" results are from MW3 at 15 feet on 7128197. "Water Before" results are from MW3 on 7129197 except <br /> TPH—d which is from MW4 on10/31/97. "Water After' results are from MW-3 on 10/21/99 except TPH-d which is from <br /> MW4 on 4130198. <br /> The concentration of MTBE in groundwater listed above was detected using EPA Method 8020, not 8260. The highest <br /> concentration of oxygenates in subsequent water samples from`geoprobe grab samples using 8260 were 0.058 µg11 of <br /> MTBE. <br /> The investigation indicated minimal contamination in the soil and groundwater. Beneficial uses of groundwater are <br /> protected, now and in the 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: no Number Decommissioned: 0 Number retained: 6 <br /> List enforcemenf'actions taken: NOR sent <br /> List enforcement actions rescinded: None <br /> V. Local Agency Re resentative Data <br /> Name: Margaret Lagorio Title: Supervising REHSISite MitigationlLOP Unit IV. <br /> . <br /> Date <br /> Signature: <br /> ',:, <br /> VI. Central Valley Regional Water Quality Control Board (RB) Notification <br /> Date Submitted to RB: Response Date: <br /> RB Staff: Marty Hartzell Response: <br /> Title: Assoc Eng�beologist <br /> VII. Additional Comments, Data, etc. <br /> Monitoring wells;�must be destroyed before final closure. <br /> This document and the related CASE CLOSURE LETTER, Shall be retained by the lead agency as part of the <br /> official site file. (08/24193) Exhibit N Page 2 of 2 <br />