Section R. 325.1743 - CasingsRule 243.
(1) The wall thickness of the casing of a dewatering well shall be selected to withstand the forces expected to be exerted on the well casing during installation and removal.(2) The casing shall extend not less than 12 inches above the working grade. The top of a casing shall be capped or covered in a manner to prevent entry of extraneous objects and to serve as a safety measure as long as the casing remains in place. When flooding is imminent, precautions shall be taken to prevent the entry of flood water into the casing. However, the casing on a well point system may extend less than 12 inches above grade when a closed piping collection network is used under vacuum and the closed piping is maintained to prevent surface waters from entering the well points.Mich. Admin. Code R. 325.1743