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`fa1 Case Closure Summary Page 2 <br /> Li,,.�g Underground Fuel Storage Tank Progr <br /> (III Release and Site Characterization Information, continued) j <br /> i <br /> Maximum Documented Contaminant Concentrations -Before and After Cleanup (in this case, the over-excavation) <br /> Contaminant Soil Soil Water Water Contaminant Soil Soil Water Water <br /> ,j (ppm) (ppm) (ppb) (ppb) (ppm) (ppm) (ppb) (ppb) <br /> Before After Before After Before After Before After <br /> s TPH (Gas) 4,400 340 17,000 59 MTBE 15 0.13 6.4 4.4 <br /> TPH (Diesel) 330 --- 200 <50 Mineral Spirits -- — — --- <br /> Benzene 39 2.4 3,100 8.2 Oil &Grease — — 10 <1.0 <br /> Toluene 170 4.9 2.000 <5.0 Heavy Metals 37 -- -- -- - <br /> Ethy'benzene 110 8.0 670 1.3 Lead 19 — — --- <br /> Xylenes 600 41 2,400 6.2 <br /> Comments (Depth of Remediation, etc.): Tanks were removed in 1993. Investigation showed soil impact to be limited to <br /> 15 feet with most of the hydrocarbon mass concentrated at 10 feet and above. 450 cubic yards of contaminated soil from a <br /> 30 feet wide by 40 feet long by 12 feet deep excavation had since been removed from site in 1998. <br /> i <br /> EI <br /> IV. Closure <br /> 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 Board Basin Plan? Yes <br /> Does corrective action protect public health for current land use? Yes <br /> Site management requirements: none <br /> Shou'Id corrective action be reviewed if land use changes?Yes <br /> Monitoring wells decommissioned: yes Number Decommissioned: 5 Number retained: 0 <br /> List enforcement actions taken: NOR sent <br /> List enforcement actions rescinded: None <br /> V. Local Agency Representative Data <br /> Name: Donn Heran Title: Director of Environmental Health <br /> Signature: Date: <br /> I <br /> I i <br /> VI. Central Valley Regional Water Quality Control Board (RB) Notification <br /> Date'.Submitted to RB: Response Date: 01/28/99 <br /> RB Staff: Mark List Response: Concurrence <br /> Title: Engineering Geologist <br /> i I <br /> VII. Additional Comments, Data, etc. <br /> One Monitor well was destroyed when site was over-excavated in 1998. Remaining monitor wells were destroyed by <br /> over6rilling and subsequently grouted on 02/12/99. <br /> I <br /> I <br /> This document and the related CASE CLOSURE LETTER, Shall be retained by the lead agency as part of the <br /> official site file. (08/24/93) Exhibit N Page 2 of 2 <br /> i <br /> s _ <br /> ,j <br />