Section R. 325.1632 - Construction of wells; casing diameter, depth, termination, and installation proceduresRule 132.
(1) Steel pipe that is used as permanent casing shall have an inside diameter of not less than 2 inches, except as provided in R 325.1632a.(2) PVC pipe that is used as permanent casing shall have an inside diameter of not less than 5 inches, except if the pipe is installed as liner pipe. PVC well casing shall be installed only in an oversized borehole without driving.(3) A casing shall extend not less than 25 feet below, and terminate not less than 12 inches above, the ground surface. A well that has less than 26 feet of casing shall not be used without obtaining written approval from the health officer pursuant to the provisions of R 325.1613.(4) The top 25 feet of a well casing shall not be used as a suction line unless the well casing is protected by a standard weight or heavier outer casing. The top of both casings shall be finished pursuant to the provisions of R 325.1641 and R 325.1643.(5) A driven steel permanent casing shall be protected by a drive shoe.(6) In a paved area, the health officer may approve, in writing, a casing termination of 2 inches or more above the ground surface if the area is not subject to flooding, if the connections and openings are threaded or welded and watertight, and if acceptable casing venting is provided.Mich. Admin. Code R. 325.1632