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} <br /> Case Closure Summary Page 2 f <br /> _ <br /> Qaking Underground Fuel Storage Tank Pam , <br /> Ir <br /> III Release and Site Characterization Information (continued) ' <br /> {. Maximum Documented Contaminant Concentrations - - Before and Atter Cleanup <br /> Contaminant Soil (ppm) Water (ppm) Contaminant' 4soil (ppm) Water (ppm) <br /> Before After Before After �I hBefore After Before After <br /> li TPH (Gas) 145' 24.03 0.95 <.050a Ethylbenzene ;�<1.0' 0.293 0.00425 <.0005$ <br /> TPH (Diesel) 3002 NA NA NA Xylene 19.0' 1.44 0.0215 <.00058 <br /> Benzene 1.1' 0.070 0.0036 <000511 Oil & Grease, f<100' NA <br /> Toluene 5.7' <.0054 0.11' <.00051 Heavy Metals <br /> Lead-organic <.5' NA <br /> a Comments:. Groundwater contamination was detected on 12/22/88 at the time of removal and confirmed with monitoring <br /> 1 well results.. Soil sample notations made for identification: 1. 2A-east@14'j on 1 22/88. 2. 1A-west@14.5' on 12122188. <br /> 3. X18 on 3119193. 4. X10 @15' on 3116/93. 5. MW6S on 6190. 6. MW4S on 51,90. 7. MW40 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" cancentrdtions. <br /> The soil after results represent residual soil contamination following two excavation' <br /> x ca vation attempts which excavated approximately <br /> 2,800 cubic yards of soil. <br /> IV. Closure <br /> Does completed corrective action protect existing beneficial uses per the Regionall�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. l <br /> Monitoring wells decommissioned: (Yes) Number Decommissioned: (14) Nrumberi retained: (0) <br /> List enforcement actions taken: NOR sent 10113189, 3!7190, 1114191, and 3/16193.'Ih <br /> List enforcement actions rescinded: None <br /> V. Local Agency Representative Data i <br />' Name: Donna Heran Title: Director of Environmental Health <br /> '3 :h <br /> Signature: Date: l� <br /> . I <br /> VI. Central Valley Regional Water Quality Control Board (RB) Notification <br /> Date Submitted to R8: 8/19/96 Response Date: 9/17/96 <br /> ,F <br />' RB Staff: J. Brathovde Response: No Further Action Required. <br />' Title: Assoc Eng Geologist <br /> V11. Additional Comments, Data, etc. i <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 remediated and tl'at 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 areas of higher concentrations of petroleum <br /> hydrocarbons have been excavated." Current groundwater results suggest that the shallow groundwater is no longer <br /> impacted by petroleum hydrocarbons. I I� <br /> This document and the related CASE CLOSURE LETTER, Shall be retained by;the lead agency as part of the official <br /> site file. (08124193) Exhibit N Page 2 of 2 <br /> li.. <br /> `'� <br />