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Corrective Action Plan Page 5 <br /> Cutter/Western Lift Site <br /> (� GPE Project No. 102.3 <br /> t December 12,2003 <br /> �•+ 3.0 SERVICE WELL INSTALLATION$; <br /> As suggested above, installation of the remedial system will require the construction of three <br /> gg , <br /> new sparge wells, and five vapor extraction wells. (Seethe attached site map (Figure 2) for <br /> L well locations). <br /> 3.1 Soil Boring Installation <br /> The new soil borings to be converted to service wells will be drilled with a 12-inch o.d. or <br /> larger hollow stemmed auger drilling equipment operated by a C-57 licensed drilling <br /> contractor. During drilling, the borings will be logged and sampled by a professional <br /> geologist supervised by a registered geologist.: The approximate depths of the borings will be <br /> as follows: <br /> Well Boring Diameter Boring Depth <br /> Sparge Wells 12 inch '55 feet <br /> Vapor Extraction Wells 12 inch 45 feet <br /> . i <br /> Soil sample collection procedures are"described in Section 5.1. <br /> 3.2 Service Well Construction <br /> Illrrrrrr The following section describes the construction of the new wells. Locking water tight well <br /> caps will be installed on top of each well as well as traffic rated well boxes. <br /> 3.2.1 Vapor Extraction Well Construction <br /> Locations of the existing vapor extraction well (VEW 1) as well as the planned five new <br /> vapor extractors are shown in Figure 2. The following table describes the construction of the <br /> vapor extraction wells: <br /> Casing 4 inch Schedule 40 PVC <br /> Screen 0.040 inch slotted 4 inch Schedule 40 PVC <br /> Screened Interval 15-45 feet ibelow ground surface (bgs)- <br /> Filter Pack . 13-45 feet,bgs <br /> Filter Pack Material 4 2 Sand E <br /> Bentonite Transition Seal .10-13 feetbgs <br /> I <br /> Annular Seal 0-10feet bgs <br /> k I <br /> The proposed screened interval of 1'S to 45 feet is greater than usual for a vapor extraction <br /> well. The reason for this is to enhance:the ability to remove sparge air, which may become <br /> trapped in the sub-surface. As air is introduced into expelled from the pilot sparge well, it <br /> will tend to`rise toward the surface. If rising air encounters a relatively impermeable clay <br /> layer, however, it may tend to become trapped against the clay. By having the nearby vapor <br /> _ i <br /> 2937 Veneman Ave.,#13240 Geo-Phase Environmental Inc. Phone 209 569-0293 <br /> Modesto,CA 95356 Fax(209)569-0295 ` <br />