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1 <br /> 3.1.2 Monitoring Well Construction <br /> Soil borings MWi, MW2, and MW3 were subsequently completed as groundwater <br /> monitoring wells The monitoring wells were installed to assess the extent of <br /> groundwater contamination beneath the site, and to provide measurement points for the <br /> determination of groundwater flow direction and hydraulic gradient Figure 2 shows the <br /> locations of the wells <br /> ' Each well was constructed with 2-inch F480 polyvinyl chloride (PVC) casing The <br /> screened interval of each well was positioned from approximately five feet above to <br /> ' fifteen feet below the encountered water table to allow for seasonal water level <br /> fluctuations The screen slot size is 0 01 inch <br /> The boring for each monitoring well was advanced with 8-inch outside diameter hollow <br /> stem augers When the augers were advanced to the desired depth of the well, the well <br /> casing was lowered down the center of the augers and set to the appropriate depth The <br /> annular space between the augers and the screened portion of the well was backfilled <br /> with Lonestar #2-12 sand As the filter pack was placed, the augers were withdrawn <br /> from the borehole so the sand flowed from the augers into the annular space of the <br /> borehole The filter pack was extended to approximately two feet above the top of the <br /> ' screened portion of the casing. A two foot seal of bentonite clay was placed in the <br /> annular space above the filter pack Since the bentonite seal was positioned above the <br /> ' water table, five gallons of potable water was added to allow the bentonite to swell The <br /> remaining annular space was backfilled to the surface with neat cement <br /> 1 <br /> Each monitor well was finished with a Universal water-tight well manhole set into <br /> ' concrete A watertight, locking cap sealed the well casing inside the manhole Boring <br /> ' logs/well details are contained in Appendix IV <br />' IPAR0492 TIL 5 <br />