Wisconsin Administrative Code
Department of Natural Resources
NR 800 - Environmental Protection - Water Supply
Chapter NR 811 - Requirements For The Operation And Design Of Community Water Systems
Subchapter II - Source Development - Groundwater
Section NR 811.14 - Special requirements for wells developed in unconsolidated formations
Current through August 26, 2024
(1) CASED AND GROUTED DEPTH. The cased and grouted depth for screened wells in unconsolidated formations shall be dependent on the controlling geologic conditions. Where practical, the grouted casing shall extend to at least 5 feet below the normal pumping water level and to within 5 feet of the top of the screen unless the grout depth is at least 60 feet.
(2) TREATMENT. Additional treatment shall be provided for wells with less than 60 feet of grouted well casing.
(3) CASING AND GROUTING THROUGH CLAY OR HARDPAN. If clay or hardpan is encountered above the formation to be developed, the protective casing and grout shall extend through the materials, but any outer casing shall be withdrawn at least 5 feet above the clay or hardpan during grouting.
(4) GRAVEL PACK. If the well is gravel packed, the gravel shall be acid resistant and free of foreign material, properly sized, washed and disinfected prior to or during placement.
(5) GROUT SEAL. A sand seal, bentonite seal, or seal constructed of both sand and bentonite shall be provided to prevent leakage into the gravel pack. The seal shall be 2 to 4 feet thick.
(6) GRAVEL REFILL AND OBSERVATION PIPES. Gravel refill pipes and observation pipes, when used, shall be surrounded by a minimum of 1.5 inches of grout if installed in the grouted annular opening. Observation pipes installed between the inner and the protective casing may be plastic. Pipes shall be incorporated into the concrete pump foundation to a point at least 4 inches above the floor, and shall terminate with a threaded cap at least 12 inches above the pumphouse floor.
