Section 812.24. Dug type well design and construction.

  Because dug wells often pose a safety hazard and a threat to groundwater quality, the department discourages their construction. Dug wells may not be constructed without written approval. When approved, they shall be constructed to meet the following requirements:

(1)   Curbing wall. The curbing wall of a dug well shall be concrete or steel and watertight to a depth of at least 2 feet below the vertical zone of contamination, but not less than 25 feet below the established ground surface. The curbing wall through the intake area shall be of adequate strength to withstand any external pressure to which it may be subjected and shall be seated firmly enough to prevent settling.

(a) Concrete curbing wall. The curbing wall shall be circular and at least 6 inches thick with concrete placed so as to be free from voids. The concrete mixture shall conform to provisions of s. NR 812.20 (1) . The curbing wall shall be reinforced vertically and horizontally with 3/8-inch rods on 12-inch centers. Rods shall lap 12 inches and be staggered, but the lap may not occur at construction joints. The curbing wall should be poured in one operation. There may not be a construction joint within 10 feet of the ground surface. Construction joints shall be left rough and shall be washed and brushed with neat cement grout before pouring of concrete is continued, if possible.

- See PDF for diagram Figure 18a. Hand pump installation protected from frost with outer casing and drainback mechanism.

(b) Steel curbing wall. A steel curbing wall shall have a thickness of at least 1/4 inch thick and assembled with welded joints.

(c) Curbing wall installation. The curbing wall shall be constructed at the surface and carried down by excavating from the interior. If wood forms are used on the exterior of a concrete curbing wall, they shall be removed before the curbing is lowered. Exterior wood forms may not be used below the ground surface. Metal forms may be left in place.

(d) Annular opening. The opening between the face of the excavation and the curbing wall through the vertical zone of contamination shall be filled with clean clay slurry.

(e) Upper terminal. The curbing wall shall extend at least 12 inches above the established ground surface. The ground shall be graded up around the curbing wall to a height of at least 6 inches above the ground surface so surface water will flow away from the well.

(2)   Dug well cover. The cover of the well curbing shall be made of reinforced watertight concrete at least 5 inches thick and of a diameter large enough to overlap the curbing wall by at least 2 inches. A drip groove shall be provided within one inch of the outer edge of the underside of the cover. The cover shall be free from joints. A pump installation access sleeve comprising a section of steel well casing pipe conforming to s. NR 812.17 (2) shall be installed in the cover at the time of pouring the concrete to fabricate the cover and shall terminate at least 12 inches above the top of the cover. The top of the cover shall be sloped to drain away from the access sleeve. A manhole, if installed, shall be provided with a 4-inch high metal curb which shall be equipped with an overlapping metal cover, the sides of which extend downward at least 1-1/2 inches. A tight joint shall be provided between the top of the curbing and the cover using a nontoxic plastic sealing compound. The manhole cover shall be locked or bolted in place to prevent entrance of water and to be safe from vandalism and accidents.

(3)   Equipment location. All pump piping, including the pump discharge or suction pipe, shall extend watertight through an access sleeve in the dug well cover.

History: Cr. Register, January, 1991, No. 421 , eff. 2-1-91.