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Case Closure Summary Page 2 <br /> ' Ling Underground Fuel Storage Tank Prog,.p <br /> III Release and Site Characterization Information (continued) <br /> Maximum Documented Contaminant Concentrations--Before and After Cleanup <br /> Contaminant Soil Soil Water Water Contaminant Before After Before il Soil a After <br /> Before After Before After (ppm) (ppb) <br /> (ppm) (Ppb) 113 15 <1 <br /> TPH(gas) 4,400 272 210 <50 Xylene 350 <2 <br /> <.5 MTBE 0.00752 51.4 <br /> Benzene 0.630 <0.002 230 <5 Lead 13.7 —' "" <br /> Toluene 3.2 0.28412 <.5 EDB 0.17 --- '— <2 <br /> Ethylbenzene 42 1.7 2.8 <br /> 3 UST were installed in 3 widely separate locations. The above list included only the 500-gallon UST sample results;the 6,600- <br /> gallon UST and 10,000-gallon UST results were not included. <br /> "Soil Before"results were from tank pull samples from Dec 1989 and the subsequent soil boring investigation on September 27, <br /> 1991. "Soil After"results were from February 1999 MW-1 installation samples although no remediation was ever performed. <br /> "Water Before"results were from the May 2002 quarter except MTBE. The MTBE results were from 02/99 MW-1 installation <br /> sample. MTBE concentration has since fallen to 3 to 5 ppb and ND. With the exception of May 2002 quarter,sample results were all <br /> below detection limits for TPH-g,BTEX,and 5 oxygenates(except MTBE)over the last 7 quarters. "Water After"results reflect data <br /> from sampling conducted in December 2002. May 2002 contamination in the groundwater samples was not repeated and could not be <br /> confirmed. <br /> Investigation showed minimal impact to soil and groundwater. Beneficial uses of groundwater are protected,now and in the future. <br /> iv. Closure <br /> Foepleted corrective action protect existing beneficial uses per the Regional Board Basin Plan? Yes <br /> pleted corrective action protect potential beneficial uses per the Regional Board Basin Plan? Yes <br /> ective action protect public health for current land use? Yes <br /> gement requirements: nonerrective action be reviewed if land use changes?Yes <br /> Monitoring wells decommissioned: No Number Decommissioned: 0 Number retained: 1 <br /> LUEstenforcementtaken: NOR sent <br /> forcemerescinded: None <br /> V. Local Agency Representative Data <br /> Name: Margaret Lagorio Title: Supervising REHS/Site Mitigation/LOP Unit IV <br /> Signature: Date: `7 3 a 3 <br /> VI. Central Valley Regional Water Quality Control Board (RB)Notification <br /> Date Submitted to RB: Response Date: <br /> RB Staff:James L. L. Barton Response: <br /> Title:Assoc Eng Geologist <br /> VII. Additional Comments, Data,etc. <br /> This document and the related CASE CLOSURE LETTER,Shall be retained by the lead agency as part of the <br /> official site file. (08124/93) Exhibit N Page 2 of 2 <br />