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L `%WW 27 October 2005 AGE-NC Project No. 96-0235 Page 10 of 11 approximately 35 feet bsg. A 1-inch PVC riser will connect the sparge points to a surface ozone generator. A proposed ozone sparge well construction diagram is depicted in Figure 3. After installing the well casing in each boring,a filter pack material will be slowly emplaced through the augers over the screen interval to approximately two feet above the screened intervals for the monitoring well. The filter pack material in the ground water monitoring wells will consist of pre- washed#3 Lonestar sand.Additional filter pack material will be added if settling occurs.A nominal 2-foot bentonite seal(bentonite chips)will be placed above the filter pack to minimize the potential for grout penetration into the screened section of the well. The bentonite seal will be formed by pouring bentonite chips into the annulus and allowing the pellets to settle on the filter pack. The bentonite pellets will be allowed to hydrate with tap water for a minimum of one-half hour prior to grouting. The remaining annular space will be filled to the ground surface with a cement grout. The grout mixture will consist of Type I/II portland neat cement and not more than 6 gallons of water per 94-pound sack of cement. The grout will be placed by pumping through tremmie pipe. A grouting inspection will be scheduled with EHD personnel. 3.3. IN-SITU OZONE SPARGING PILOT STUDY The typical ozone system is an in-situ air stripping process utilizing fine bubbles of ozone-rich air, injected into saturated soil to extract and decompose dissolved petroleum hydrocarbon constituents. An ozone generator is utilized to produce gaseous ozone which is injected into the subsurface via microsparge points. The "microbubbles" (approximately 50 micrometers) are forced out into the surrounding saturated soil and react with the target analytes, producing carbon dioxide and water. The frequency and duration of ozone injection periods can be regulated at the ozone generator control box. Initially, operation of the ozone injection system will be based on the manufacturer's recommendations. Injection rates, frequency and duration may be adjusted to compensate for site conditions during the pilot test.The ozone sparge feasibility test will be performed for approximately 24 week;ground water samples will be collected monthly from the existing monitoring wells MW-9 and MW-10 and well EW-1 within the sparge well network. Samples will be analyzed at a DHS- certified laboratory to evaluate the effectiveness of the ozone sparge system.The grab water samples will be analyzed for the following constituents: • TPH-g in accordance with EPA Method 8015 Modified; • BTEX compounds MTBE and 1,2-DCA by EPA Method 8260 Modified and • General Mineral (metals and anions) CAM 17 Metals Sb, As, Ba, Be, Cd, Cr, Co, Cu, Pb, Advanced GeoEnvironmental,Inc.