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1 . 0 INTRODUCTION <br /> This submittal presents Aqua Science Engineers, Inc. (ASE)'s second six <br /> month's operation report of a ozone-sparging remediation system at the <br /> Unocal Service Station located at 574 West Grant Line Road in Tracy, <br /> California {Figures 1 and 2). This report has been prepared on behalf of <br /> Mr. Satnam Singh, owner of the property, as required by the San Joaquin <br /> County Public Health Services, Environmental Health Division (PHS-EHD). <br /> 2 . 0 REMEDIATION SYSTEM COMPONENTS <br /> 2- 1 Ozone-Sparging Wells <br /> The remediation system incorporates the use of ten (10) ozone-sparge <br /> wells. The locations of these wells are shown on Figure 3. A cross- <br /> sectional view of a typical ozone sparging well is included as Figure 4. ASE <br /> has assumed a conservative radius of influence of 15-feet based on data <br /> from the air-sparging test at the site. The wells have been located to <br /> destroy hydrocarbons within and downgradient of the former USTs. All <br /> ten ports on the ozone generation unit are utilized. <br /> On July 1 and 2, 2002, Gregg Drilling of Martinez, California drilled ten <br /> soil borings using a drill rig equipped with 5-inch diameter hollow-stem <br /> augers. The borings were subsequently turned into ozone-sparging wells <br /> OS-1 through OS-10. The wells were constructed with 314-inch diameter <br /> PVC well casing. Ozone is then sparged from the casing through a 2-inch <br /> diameter by 30-inch long sparge point with 10-50 micron perforations. <br /> These sparge points are placed in the location of the permeable water- <br /> bearing zone approximately 15-feet bgs. Lonestar #2116 sand was placed <br /> between the sparge point and the boring from the bottom of the boring to <br /> 1-foot above the top of the sparge point. A 0.5-foot thick bentonite layer <br /> was placed between the sandpack and the overlying cement sanitary seal. <br /> A Portland cement sanitary seal was placed above the bentonite layer to <br /> prevent surface water from infiltrating into the well. The wellheads are <br /> piped individually into the ozone-sparging manifold, which is piped <br /> directly to the ozone generator. <br /> 2"2 Ozone Delivery, Tubing Tnstallati�an <br /> Between July 29 and August 1, 2002, Crutchfield, Construction and ASE <br /> personnel laid-out the trench locations, sawcut the existing asphalt, <br /> excavated the trenches to 18-inches below grade, installed the tubing a n d <br /> Singh's Unocal System Second Six Month's Operation Report — September 2003 <br /> -1- <br />