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Case Closure Summary Page 2 <br /> Lecing Underground Fuel Storage Tank Pro ®RAFT <br /> P <br /> III Release and Site Characterization Information (continued) II <br /> Maximum Documented Contaminant Concentrations - - Before and After Cleanup <br /> Contaminant Soil (ppm) Water (ppm) Contaminant I�Soit (ppm) Water (ppm) <br /> I Before After Before After Before After Before After <br /> TPH (Gas) 145' 24.0' 0.95 <.0508 Ethylbenzene i'<1.0' 0.29' 0.00425 <.00058 <br /> TPH (Diesel) 3002 NA NA NA Xylene ;� 19.0' 1.44 0.0215 <.0005$ <br /> 4 , 4 B g <100' NA <br /> 3 Benzene 1.1 0.074 O.OD3 <.0005 Oil 8< Grease. <br /> Toluene 5.7' <.0054 0.117 <.00059 Hearty Metals <br /> I Lead-organic} j<.5' NA <br /> F <br /> ents:. Groundwater contamination was detected on 12/22/88 at the time of removal and confirmed with monitoring I <br /> ults.. Soil sample notations made for identification: 1. 2A-east@14'ion 12122188. 2. 1A-west@14.5' on 12122185. <br /> on 3119193. 4. X10 @15' on 3116193. 5. MW6S on 6190. 6. MW4S on 5190. 7. MW4D on 3/90. 8. Groundwater <br /> from all monitoring wells since 10192 with the exception of MW9, MW10, MW11 and MW12 on 5/5195. Subsequent <br /> samples from these wells on 9112195 reflect the above referenced "after" concentrations. <br /> The soil after results represent residual soil contamination following two excavation attempts which excavated approximately <br /> 2,800 cubic yards of soil. 1N I <br /> IV. Closure <br /> Does completed corrective action protect existing beneficial uses per the RegionalBoard 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 /> l Site management requirements: None. <br /> Should corrective action be reviewed if land use changes? (Yes) <br /> Monitoring wells decommissioned: (Yes) Number Decommissioned: ( ) Number,retained: (0) <br /> List enforcement actions taken: NOR sent 10113/89, 317190, 1114191, and 3116/93:1 <br /> t � <br /> List enforcement actions rescinded: None f� <br /> V. Local Agency Representative Data <br /> Name: Donna Heran Title: Director of Environmental Health <br /> i. <br /> Signature: Date: <br /> Vl. Central Valley Regional Water Quality Control Board (RB) Notification <br /> Date Submitted to RB: Response Date: ''i <br /> I RB Staff: J. Brathovde Response:;' <br /> Title: Assoc Eng Geologist <br /> j <br /> , <br /> VII. Additional Comments, Data, etc. <br /> Diane Lesko Sarmiento, California Registered PE#047804 indicated in the 'Revised Closure Report" dated July 3, 1996 that <br /> the sources of petroleum hydrocarbons have been removed and remediate d 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 mg/kg benzene) and the data suggests that <br /> the extent of the remaining petroleum hydrocarbons is limited and that areas of higher concentrations of petroleum <br /> hydrocarbons have been excavated." Current groundwater results suggest.1hat the shallow groundwater is no longer <br /> impacted by petroleum hydrocarbons. f� k <br /> This document and the related CASE CLOSUR5LETTER, Shall be retained by the lead agency as part o the official <br /> site file. (08124/93) Exhibit N Page 2 of 2 I <br />