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' GEOMATRIX <br /> performed) and will select the well materials and techniques for well completion to be <br /> ' compatible with the subsurface conditions and the intended use of the well. Construction of all <br /> wells will be in conformance with the following provisions. A TYPICAL MONITORING <br /> ' WELL CONSTRUCTION DIAGRAM is attached. <br /> ' 2.1 WELL SCREEN AND CASING <br /> The well casing will generally consist of threaded stainless steel or schedule 40 (minimum) <br /> ' polyvinyl chloride (PVC) casing. The inside diameter of the casing will be large enough to <br /> permit easy passage of an appropriate water-level probe and equipment for purging wells and <br /> ' water sample collection. <br /> ' The well screen will generally consist of machine-slotted PVC or wire-wrapped stainless steel <br /> screen. The slot sizes will be compatible with the selected filter material. The screened <br /> ' sections will provide flow between the target zone and the well, allowing efficiency in well <br /> ' development and collection of representative samples. <br /> ' 2.2 FILTER MATERIAL <br /> Filter material will be well-graded, clean sand (generally less than 2 percent by weight passing <br /> ' a No. 200 sieve and less than 5 percent by weight of calcareous material). The filter material <br /> will be either a standard sand gradation designed for a range of anticipated soil types or a sand <br /> ' gradation specifically designed to fit the soils collected from anticipated well completion zone. <br /> ' 2.3 SETTING SCREENS AND RISER CASING <br /> Upon completion of drilling and/or geophysical logging, the boring will be sounded to verify <br /> ' the total depth, and the well casing will be assembled and lowered into the boring. Well <br /> casing materials will be measured to the nearest 0.1 foot and steam-cleaned before being <br /> ' lowered into the borehole. The well assembly will be designed so that the well screen is <br /> opposite the target zone. The bottom of the well will be fitted with a secure bottom-end cap. <br /> No PVC cement or other solvents will be used to fasten the well casing joints, well screen <br /> ' joints, or end caps. When installing wells in an open borehole, stainless steel centralizers will <br /> INSTALLATION AND DESTRUCTION OF WELLS Page 2 of 8 <br /> MSOPROTO-IW.TXT REVISION DATE:MARCH 1996 IW-2 <br />