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5 , 0 REMEDIATION SYSTEM DESIGN -5. 1 _D2D=-_SpDar_ging Wells The remediation system incorporates the use of ten (10) ozone-sparge wells. The locations of these wells are shown on Figure 3. A cross- sectional view of a typical ozone sparging well is included as Figure 4. ASE has assumed a conservative radius of influence of 15-feet based on data from the air-sparging test at the site. The wells have been located to destroy hydrocarbons within and downgradient of the former USTs. All ten ports on the ozone generation unit are utilized. On July 1 and 2, 2002, Gregg Drilling of Martinez, California drilled t e n soil borings using a drill rig equipped with 5-inch diameter hollow-stem augers. The borings were subsequently turned into ozone-sparging wells OS-1 through OS-10. See Appendix A for the boring/well completion logs. The wells were constructed with 314-inch diameter PVC well casing. Ozone is then sparged from the casing through a 2-inch diameter by 30- inch long sparge point with 10-50 micron perforations. These sparge points are placed in the location of the permeable water-bearing zone approximately 15-feet bgs. Lonestar #2116 sand was placed between the sparge point and the boring from the bottom of the boring to 1 -foot above the top of the sparge point. A 0.5-foot thick bentonite layer was placed between the sandpack and the overlying cement sanitary seal. A Portland cement sanitary seal was placed above the bentonite layer to prevent surface water from infiltrating into the well. The wellheads are piped individually into the ozone-sparging manifold, which is piped directly to the ozone generator. -5 -2 Ozoine, Delivery Tubing Installation Between July 29 and August 1, 2002, Crutchfield Construction and ASE personnel laid-out the trench locations, sawcut the existing asphalt, excavated the trenches to 18-inches below grade, installed the tubing and well head plumbing, offhauled the spoils, backfilled the trenches with imported material, installed well boxes, and resurfaced, Figure 5. The air/ozone mixture is pumped through double contained ozone- resistant poly tubing from the C-Sparing System to the sparging wells. This tubing consists of a 114-inch diameter inner transport tubing with a 718-inch outside diameter secondary containment tube. This tubing h a s been buried through narrow trenches cut through the asphalt/concrete surface. The tubing was placed into the trenches, buried with sand and Singh's Unocal System Installation and Operation Report — October 2002 -2-