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• Ozone Microsparge System First Semi-Annual Status Report—76 Branded(Former BP)Facility No 11192,Stockton,California` <br /> September 2,2003 <br /> The sparge wells are constructed with 2-inch diameter ozone sparge points attached to '/-inch blank <br /> Schedule 80 PVC casing The ozone sparge points are composed of 30-inch long macroporous <br /> plastic Lonestar #2116 sand is placed in the annular space from the bottom of the boring (30 feet <br /> below ground surface) to 15 feet above the top of each sparge point The two feet of annular space <br /> above the sand is filled with bentorute, hydrated by the groundwater in the boring, and the <br /> remainder of the annular space in each boring is sealed with neat cement_ Sparge points are located <br /> approximately 16 feet below the surface of the groundwater table - <br /> The ozone microsparge control panel is mounted on a unistrut frame in the northeast comer of the <br /> site The panel includes an ozone generator, air compressor, the added oxygen generator and a <br /> programmable tinier/controller Sparge points are connected to the panel by 318" HDPE tubing <br /> Each sparge point has a dedicated line The tubing was pulled through Schedule 80 PVC <br /> conveyance piping for added protection <br /> Groundwater Sampling <br /> In order to evaluate system effectiveness, periodic sampling of selected groundwater monitoring <br /> wells has been performed at the site Wells MW-3 and MW-4 were selected for sampling and have <br /> been sampled on a monthly basis starting in January of 2003 Well MW-3 is adjacent to the <br /> underground storage tanks (USTs) and MW-4 is crossgradient of the site Each well is within the <br /> treatment area and the zone of influence of one or more sparge points These `wells are <br /> approximately 100 feet apart Both wells MW-3 and MW-4 have extensive histoncal sampling <br /> data prior to the system activation These wells were installed in 1990, and are currently sampled <br /> quarterly A historical sampling data table for the monitoring well network is attached as Appendix <br /> A <br /> Groundwater samples from MW-3 and MW-4 were analyzed for TPHg, benzene, toluene, <br /> ethylbenzene, and total xylenes (BTEX), MtBE, and tertiary butyl alcohol (TBA) by EPA Method <br /> 8260 ' Groundwater analytical results for the two wells are presented in Table 1 The complete <br /> laboratory analytical reports and chain of custody records for the monthly groundwater sampling <br /> are attached in Appendix B <br /> f f , <br /> l <br /> k v <br /> J S t <br /> f <br /> s <br /> 140245 10 12 <br />