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k <br /> Case Closure Summary Page 2 <br />' Leaking Underground Fuel Storage Tank Program <br /> III Release and Site Characterization Information (continued) <br /> Maximum Documented Contaminant Concentrations - - Before and After Cleanup <br /> a <br /> Contaminant Soil (ppm) Water (ppm) Contaminant Soil (ppm) Water (ppm) <br /> Before After Before After Before After Before After <br /> TPH (Gas) 145' 24.03 0.95 <.0508 Ethylbenzene� <1.0' 0.293 0.00425 <.00058 <br /> TPH (Diesel) 3002 NA NA NA Xyfene 19.0' 1.4` 0.0215 <.00056 f <br /> Benzene 1.1' 0.0744 0.0036 <A005° Oil & Grease <100' NA <br /> Toluene 5.7' <.0054 0.11' <.00056 Heavy Metals <br /> Lead-organic NA <br /> Comments.. Groundwater contamination was detected on 12/22/88 at the time of removal and confirmed with monitoring <br /> well results.. Soil sample notations made for identification: 1. 2A-east@14' on 12122!88. 2. 1A-west@14.5' on 12122188. <br /> 3. X18 on 3119193. 4. X10 @15' on 3116/93. 5. MW6S on 6190. 6. MW4S* 5190. 7. MW4D on 3190. 8. Groundwater <br /> results from all monitoring wells since 10192 with the exception of MW9, MW10, MW11 and MW12 on 515195. Subsequent <br /> samples from these wells on 9112195 reflect the above referenced "after" concentrations. <br /> 1� <br /> The soil after results represent residual soil contamination following two excavation {attempts which excavated approximately <br /> 2,800 cubic yards of soil. <br /> + IV. Closure I <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,lBoard Basin Plan? Yes. <br /> Does corrective action protect public health for current land use? Yes. <br /> l <br /> Site management requirements: None. <br /> Should corrective action be reviewed if land use changes? Yes. �l k <br /> Monitoring wells decommissioned: (Yes) Number Decommissioned: (14) Number stained: (0) <br /> E <br /> List enforcement actions taken: NOR sent 10113189, 317190, 1114191, and 3/16/93. <br /> List enforcement actions rescinded: None R <br /> V. Local Agency Representative Data �} <br /> i Name: Donna Heran Title: Director of Environmental Health <br /> Signature: '� Date: <br /> -�1 <br /> VI. Central Valley Regional Water Quality Control Board (RB) Notification <br /> Date Submitted to RB: 8119196 Response Date: 9/12196 <br /> RB Staff. J. Brathovde Response: No Further Action Required. <br /> Title: Assoc Eng Geologist <br /> f V11. Additional Comments, Data, etc. } <br /> Diane Lesko Sarmiento, California Registered PE#047804 indicated in the "Revised]Closure Report" dated July 3, 1996 that <br /> a the sources of petroleum hydrocarbons have been removed and remediated and that the residual soil contamination would <br /> not likely adversely impact water quality or human health. D. Sarmiento further indicated that "The mass of petroleum <br /> hydrocarbons remaining in soil at the site cannot be reasonably estimated. However the concentrations of residual <br /> petroleum hydrocarbons are low (less than 25 mg/kg TPH-g and less than .33 mglkg benzene) and the data suggests that <br /> the extent of the remaining petroleum hydrocarbons is limited and that areaslof higher concentrations of petroleum I <br /> hydrocarbons have been excavated." Current groundwater results suggest that the shallow groundwater is no longer <br /> impacted by petroleum 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. (08/24/93) Exhibit N Page 2 of 2 s <br /> l 1; IyL <br /> ,�a <br />