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10.3 Well Casing Well casing must consist of materials that will ensure adequate protection <br /> against failure for the intended use of the well <br /> 10.3.1 All casing must be new or unused pipe, except that casing recovered when a well is <br /> modified or replaced may be reused in the new well if it will ensure satisfactory well <br /> performance. PVC casing must not be exposed above the ground surface. All surface <br /> casing must be steel piped. All casing must be undamaged, free of pits and <br /> corrosion, and free of contamination. Used oilfield pipe must not be installed in any <br /> well. Corrugated metal casing must not be used in well construction. <br /> 10.3.2 <br /> 10.3.2 Temporary surface casing should be removed from the borehole prior to or during <br /> grouting if it is not treated as driven surface casing. Where ground conditions are <br /> such that removal of the temporary casing is not feasible, a variance request must be <br /> submitted to and written approval must be obtained from the Board prior to grouting <br /> of the annulus between the temporary casing and the surface or production casing. <br /> The variance request must be prepared by a water well construction contractor and <br /> must describe the conditions which prevent the temporary casing from being <br /> removed. <br /> 10.3.3 The well casing inside diameter(ID) or pitless adapter must be sufficient to accept <br /> a pump capable of producing the desired production rate. The following minimum <br /> ID (nominal) requirements apply to the specified type of well casing: <br /> a. Steel well casing: 4.5 inch ID <br /> b. PVC well casing: 4.0 inch ID <br /> 10.3.4 All casing wall thickness must be adequate to prevent collapse due to hydrostatic <br /> pressures. The following minimum wall thicknesses apply to the specified type of <br /> well casings: <br /> a. Steel well casing: 0.188 inches <br /> b. PVC well casing: 0.237 inches (Schedule 40) <br /> c. Precast concrete rings: 3.00 inches <br /> 10.3.5 Casing Perforation —Casing perforation methods or designs must not result in <br /> inclusions or debris inside of the well casing. Any inclusions or debris must be <br /> removed after perforation. Oxygen-acetylene torch-cut perforations on well casing are <br /> prohibited on well casings less than 5 inches ID. <br /> 10.4 Construction Procedures The excavation of the borehole, selection and installation of the <br /> casing, grouting, development,and disinfection of a new well, and repair or deepening of an <br /> existing well, must protect the health and safety of the public utilizing workmanship and <br /> materials that match the intended use of the well. <br /> 10.4.1 Centralizers—Centralizer materials attached to the casing and left in the borehole must be <br /> metal or plastic. <br /> a. Pre-manufactured centralizers must be properly sized for the intended use, be <br /> intended for use in water wells, and must be used in accordance with the <br /> manufacturer's guidelines and recommendations. <br /> b. Contractor-fabricated centralizers must be durable enough to survive the placement of <br /> the casing in the borehole and must be rigid enough that they will provide the intended <br /> centralization for the casing. <br /> c. Centralizer devices must be properly sized to maintain the minimum required annular <br /> space in grouted intervals between the casing and the borehole or between strings of <br />