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Case Closure Summary <br /> Leaking Underground Fuel Storage Tank Program <br /> ARCO Service Station No. 4932 <br /> 16 East Harding Way, Stockton, California <br /> III. Release and Site Characterization Information continued <br /> Maximum Documented Contaminant Concentrations --Before and After Cleanup <br /> Contaminant Soil (ppm) Water (ppm) Contaminant Soil (ppm) Water (ppm) <br /> Before After Before After Before After Before After <br /> TPH(Gas) 5,430 NA 220 0.100 Xylenes 662 NA 41 <0.001 <br /> TPH (Diesel) <5.0 NA NA NA MTBE 684 NA 708 0.096 <br /> Benzene 23 NA 11 <0.0005 1,2-DCA <0.005 NA 4.4 0.0032 <br /> Toluene 131 NA 250 <0.0005 EDB <0.005 NA <0.0005 <0.0005 <br /> Eth (benzene 103 NA 10 <0.0005 Lead 240 NA <0.050 NA <br /> Comments: The 'Soil Before' concentrations for TPH (gas) and toluene are from sample D4 @ 11 feet on 6/2/1999, TPH- <br /> (diesel)from MW-10 @ 20 feet on 6/10/2002, benzene from D5 @ 4 feet on 05/26/1999, ethylbenzene from D4 @ 11 feet <br /> on 6/2/1999 and D5 @ 8.5 feet on 6/9/1999, xylenes from D5 @ 8.5 feet on 6/9/1999, MTBE from MW-4 @ 25 feet on <br /> 8/21/2000, 1,2-DCA and EDB from DMW-4 @ 40 feet on 01/16/2008, and lead from D3 @ 4 feet on 05/28/1999. 'Soil <br /> After' concentrations were not collected. The 'Groundwater Before' concentrations for TPH (gas) are from EW-1 on <br /> 07/29/2003, benzene from MW-4 on 09/5/2000 and 3/5/2001, toluene from MW4 on 11/20/2002, ethylbenzene and total <br /> xylenes from MW-4 on 07/12/2002, MTBE from MW4 on 9/5/2000, 1,2-DCA from MW-4 on 7/29/2003, EDB from MW-4 on <br /> 7/11/2005, and lead from MW-12 on 03/27/2012. 'Groundwater After' concentrations for TPH (gas)from MW-4 on <br /> 8/19/2013, benzene, toluene, ethylbenzene total xylenes, MTBE and EDB are from EW-4 on 11/26/2013, and 1,2-DCA from <br /> MW-6 on 11/26/2013. NA—not analyzed <br /> IV. Closure <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 /> Should corrective action be reviewed if land use changes? Yes <br /> Monitoring/Vapor wells decommissioned: No Number Decommissioned: 0 Number retained: 35 <br /> List enforcement actions taken: NOR on 06/03/1999, 08/21/2006, 01/29/2014 <br /> List enforcement actions rescinded: None <br /> V. Local Agency Representative Data <br /> Name: Adrienne Ellsaesser, REHS Title: Program Coordinator <br /> Si nature: <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: Engineering Geologist <br /> VII. Additional Comments, Data, etc. <br /> Remediation by dual-phase extraction (soil vapor and groundwater extraction)occurred between May 2003 and <br /> January/FebruaryJanuary/February 2008, and ozone injection occurred between July 2005 and September 2011. <br /> This document and the related CASE CLOSURE LETTER shall be retained by the lead agency as part of the official site file. <br /> Page 2 <br />