Section 811.14. Special requirements for wells developed in unconsolidated formations.

 

(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.

(a) Continuous disinfection shall be provided for wells with less than 60 feet of grouted well casing.

(b) Additional detention time and treatment shall be provided when the department determines that additional protection is necessary.

(c) Wells with less than 30 feet of grouted well casing shall be provided with treatment meeting the groundwater under the direct influence of surface water requirements found in ss. NR 810.30 , 810.31 , 810.33 , 810.34 , 810.35 , 810.36 , 810.37 , 810.38 , 810.39 and 810.40 .

(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to be developed, the protective casing and grout shall extend through the materials, but any outer casing shall be withdrawn at least 5 feet above the clay or hardpan during grouting.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 or bentonite seal to prevent leakage of grout into the gravel pack or screen shall be provided. The seal shall be no more than 2 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.

History: CR 09-073 : cr. Register November 2010 No. 659 , eff. 12-1-10.