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i <br /> L� `, " 1 <br /> I!! R� R_elease and Site Charactet°on Information (continued) <br /> Maximum Documented Contaminant Concentrations --Before and After Cleanup <br /> Contaminant Soil (ppm) Water (ppm) Contaminant Soil (ppm) Water (ppm) <br /> Beforel After2 Before3 After4 II Beforel After Before After <br /> TPH (Gas[TFHC) 3,800 3,300 <9.0 0.0 Ethylbenzene = NA 64 <0.0005 <0.0005 <br /> TPH (Diesel) NA NA NA Xylene j ° 220 220 <0.0005 <0.0005 <br /> l Benzene 22 8.7 <0.0005 <0.0005 <br /> Toluene 110 79 <0.0005 <0.0005 MTBE i NA I NA I NA NA �yy <br /> Comments: NA: Not analyzed. I <br /> j 1. Soil sample, SJMB2/A collected on 8128186 at 25 feet below ground sU ace(bgs) from beneath the former gasoline <br /> tank. <br /> 2. Soil sample, BH31, was collected on 10/28/86 at 31 feet which was thI bottom of the excavation. Subsequent soil <br /> borings were drilled and sampled to determine the extent of the remaining soil contamination. The last soil samples <br /> which were collected indicated remaining contamination (ppm) at 30 feet bgs of <5.0 benzene, 5.0 toluene, 36 <br /> ethylbenzene, 290 xylene, and 2,100 TPH-gas. <br /> 3. Groundwater sample collected on 1130187 from MW1. <br /> 4. Groundwater sample collected on 1219/96 from MW5. <br /> �i <br /> IV. Closure <br /> Yes. <br /> Does completed corrective action protect existing beneficial uses per the Regional Board Basin Pian? <br /> it M <br /> Does completed corrective action protect potential beneficial uses per the Regional Board Basin Plan? Yes. <br /> i <br /> Does corrective action protect public health for current land use? Yes. <br /> Il i <br /> Site management requirements: None. a C <br /> Should corrective action be reviewed if land use changes?Yes. <br /> MonitoringNapor wells decommissioned: Number Decommissioned: Number retained: <br /> i¢ <br /> i List enforcement actions taken: NOR dated 2110/92 j <br /> List enforcement actions rescinded: None i <br /> i <br /> I , <br /> V. Local Agency Representative Data i <br /> Name: Donna Heran Title: Director of Environmental Health, i <br /> I <br /> Signature: -- Date: <br /> 2 f <br /> VI. Central Valley Regional Water Quality Control Board (RB) Notification. <br /> Date Submitted to RB: Response Date: <br /> Ij <br /> RB Staff: J. Brathovde Response: <br /> Title: Assoc Eng Geologist <br /> j <br /> VII. Additional Comments, Data, etc. <br /> Karla Brasaemle, R.G. #6077 stated that the site should be closed with no,further investigative or monitoring actions <br /> required. Karla Brasaemle stated that it was highly unlikely that contaminants will impact groundwater at the site for several <br /> reasons: 1) The predominantly asphalt surface prevents surface water infiltrating1the vadose zone and transporting <br /> contamination down to the water table; 2)The contaminant source, i.e. the gasoline UST and a large portion of the <br /> contaminant mass have been removed; 3)The residual soil contarninatioiril will degrade over time; and 4) Contamination in <br /> samples collected below 31 feet bgs were detected at very low concentrations compared to concentrations in samples <br /> collected above 31 feet bgs. <br /> i <br /> This document and the related CASE CLOSURE LETTER and shall be retained by the lead agency as part of the official site file. <br /> Page 2 of 2 <br /> b <br /> Ij <br /> S Y <br />