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27 March 2000 AGF-NC Project No, 98-0450 Page 14 of 19 auC7 The filter pack will be placed adjacent to the screen from the bottom of the boring to a point approximately one lbot above the top of the lower screen. A three-loot interval of bentonite pellets (internal seal) will be placed above the first litter pack. Potable water will be used to hydrate the bentonite in accordance with manufactUres specifications to ensure a seal has been achieved. A second filter pack will be placed adjacent to the second screen from the top of the internal seal to a point approximately I-foot above the top of the upper screen. A one-loot interval of bentonitc pellets (annular seal) will be placed above the upper filter pack. Potable water will be used to hydrate the bentonite: in accordance with manulaCtures specifications to ensure a seal has been achieved. The remaining annular spaces will he filled to the ground surface with a cement grout. The grout mixture will consist of Type I/I1 por€land neat cement and not more than 10 gallons of water per 94-pound sack of cement. A traffic-rated well box will be installed over the: wells. in accordance with County regulations. A dual-SVE well construction diagram is depicted in Figure 9. Four SVE wells will be completed with one 2-inch diameter, schedule 40 PVC well casing emplaced throu"ll the 8-inch hollow stem augers. Due to the presence of impacted ground water at the southern ed�ue of the site and the potential for southerly migration of the contaminants, three of the SVf; recovery- wells will be installed at a 30 degre-c angle ti•om vertical under the northern edge of Lodi Avenue. One of the wells will be vertically. The recovery SVF wells will utilize ten Leet of slotted well casing (0.020-inch screen size) from 40 to 50 tcct bsg. A 413 Lonestar Lapis Luster sand will be poured down the annulus between the well casing and the inner wall of the hollow stem auger. The filter pack will be placed adjacent to the screen from the bottom of the boring to a point approximately one foot above the top of the screen. A two-foot interval ofbentonite pellets (annular seal) will be placed above the filter pack. hive gallons of potable water will be used to hydrate the bentonite in accordance with manufactures specifications to ensure a seal has been achieved. The remaining annular spaces will be filled to the ground surface with a cement grout. The grout mixture will consist ofType 1/11 portland neat cement and not more than 10 gallons of water per 94-pound sack of cement. The grout will be placed by pumping through tremmie pipe. A traffic-rated well box will be installed over the wells, in accordance with County regulations. An SVEwell construction dia�oram is depicted in ]Figure 10. 5.2.2. Soil Vapor Fxtraetion Piping System A network of two-inch diameter. schedule 40 PVC piping will be installed six inches below the surface of the site. The PVC. piping will be routed from each SVL well head to a vapor dropout drum; the vapor dropout drum will be directly connected to the SVE. A PVC ball valve will be installed at each SVE well head so that vapor can be drawn from each well independently. A plan of the proposed piping system and enclosed SVE unit location are depicted in Figure 8, Idtrrnc•cd GcuErn irqumrutal.Irc.