Well Screens. All wells that obtain water from aquifers in Hydrogeologic Areas 1 and 2 shall be equipped with a screen that shall adequately prevent the entrance of formation material into the well during use. Well screens shall have sufficient structural strength to accomplish the purpose for which they are installed. Well screen openings shall provide, so far as is practical, the maximum amount of open area, consistent with strength of screen material and sediment grain size of the water-bearing formation to permit maximum transmission without clogging. Well screens, other than those made commercially, constructed by creating openings or slots in the casing, or liner, or both, by any mechanical contrivance are prohibited unless approved by the Approving Authority in a special permit condition. The well screen shall be provided with fittings necessary to seal the screen to the casing. If the screen diameter is smaller than the casing diameter, then extension of the screen blank section to at least 20 feet above the base of the main casing is required, or a packer or a reducer fitting shall be used. A fitting shall be provided to close the bottom of the screen. Gravel-Packed Wells. Gravel, which is packed in the annular space, shall be water-washed, disinfected, and free from clay, silt, and organic material. Gravel pack may not connect aquifers.