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Corrective Action Plan Page 9 <br /> Former Manna Pro Site <br /> Project No 207 3 <br /> February 16,2001 <br />' The proposed screened interval of 20 to 50 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 <br /> become trapped in the sub-surface As air is introduced into expelled from the pilot <br />' sparge well, it will tend to rise toward the surface If rising air encounters a relatively <br /> impermeable clay layer, however, it may tend to become trapped against the clay By <br /> I having the nearby vapor extraction well screened deeper, any such trapped air should tend <br /> to migrate toward the extraction well, where it may be removed along with any entrained <br /> hydrocarbons <br />' 3.2.2 Air Sparge Well Construction <br /> I For the first phase, one existing well (ASW-1) and one new well, designated ASW-2 will <br /> be used Possible second phase well locations are also shown in the figure The <br /> following table describes the construction of the air sparge wells <br /> Casing 2" Schedule 40 PVC <br /> Screen 0 010 Slotted Schedule 40 PVC <br /> Screened Interval 50-55 feet below ground surface (bgs) <br /> Filter Pack 48-55 feet bgs <br /> • Filter Pack Material #3 Monterey sand <br /> Bentonite Transition Seal 45-48 feet bgs <br /> Annular Seal 0-45 feet bgs <br /> The sparge wells will be screened to expel air near the bottom or slightly below the main <br /> mass of the contaminant This placement will allow several feet of vertical space in <br />' which the air may penetrate deeper into the native formation before beginning to rise and <br /> spread through the main contaminant mass <br /> 3.3 Well Development <br /> The new wells will not be used for routine groundwater sampling Nevertheless, each <br /> new Vapor Extraction Well and Air Sparge Well will be developed after the well sealing <br /> materials have set for at least 48 hours using mechanical surging and pumping, or bailing <br /> methods until a clear stream of water is generated This will be done to facilitate better <br /> air flow through the well filter pack material All development water will be <br /> containerized in 55 gallon DOT approved containers and stored on site until its disposal <br /> can be arranged <br /> 3.4 Waste Disposal <br /> All waste generated during the well installation and development will be containerized in <br /> DOT approved containers to await proper disposal <br /> 2937 Veneman Ave,#13240 Geo-Phase Environmental Inc Phone(209)569-0293 <br /> Modesto,CA 95356 Fax(209)569-0295 <br /> I <br />