Section NR 130.110 - Management of drilling mud and cuttings(1) MUD PITS. Explorers who choose to construct excavated pits for the storage and disposal of drilling mud and cuttings from drillholes shall construct the pits in accordance with all of the following:(a) The base of the pit shall not be at or below the groundwater table at the time of the drilling activity and shall be constructed such that the base will remain above the normal local groundwater elevation. The pit shall be constructed of sufficient volume to contain all anticipated fluid, drilling mud, cuttings, drilling additives and other materials expected to be placed in the pit and shall not be located in areas that receive excessive amounts of runoff or are susceptible to erosion.(b) If the drillhole is expected to encounter metallic-sulfide bearing rock, the walls and base of the pit shall be lined with a minimum of one inch of bentonite or bentonite grout, a 20-mil or greater polyvinyl chloride or polyethylene geomembrane, or an equivalent liner material approved by the department in writing.(2) DISPOSAL OF DRILLING MUD AND CUTTINGS.(a) Drilling mud and cuttings from drillholes that penetrate 50 feet or more of metallic sulfide-bearing rock shall be disposed of in accordance with one of the following: 1. Disposed at a lined, engineered solid waste facility licensed under ch. 289, Stats. Prior to disposal of the drilling mud and cuttings, any free water from the mud pit or other containment feature shall be removed and reused or properly disposed of in accordance with state and federal law. The mud and cuttings shall be mixed with either concrete, cement or lime in sufficient quantities to neutralize any acidity generated by the oxidation of the metallic sulfide minerals either at the drilling site or at the solid waste facility prior to disposal. If the cuttings were contained in a mud pit lined with plastic liner material, the liner shall be removed and disposed of at a lined, engineered solid waste facility licensed under ch. 289, Stats., and the pit shall be backfilled with native soils.2. Disposed on site within the mud pit. Prior to in-place disposal of the drilling mud and cuttings, any free water from the mud pit shall be removed and reused or properly disposed of in accordance with state and federal law. The drilling mud and cuttings shall be mixed with a sufficient amount of cement to solidify the mud and cuttings and the pit shall be backfilled with native soils. If the mud pit is lined with plastic liner material, the liner shall either be removed prior to addition of cement to the drilling mud and cuttings, or the sides of the liner shall be folded over the top of the drilling mud and cuttings prior to backfilling the pit.(b) Drilling mud and cuttings from drillholes that penetrate 50 feet or less of metallic sulfide-bearing rock may be disposed on site within the mud pit. Prior to in-place disposal of the drilling mud and cuttings, any free water from the mud pit shall be removed and reused or properly disposed of in accordance with state and federal law. The drilling mud and cuttings shall be mixed with bentonite, cement, or other clean fill and the pit shall be backfilled with native soils. If the mud pit is lined with plastic liner material, the liner shall either be removed prior to addition of cement, bentonite or other material to the drilling mud and cuttings, or the sides of the liner shall be folded over the top of the drilling mud and cuttings prior to backfilling the pit.Wis. Admin. Code Department of Natural Resources NR 130.110
Adopted by, CR 20-043: cr. Register December 2021 No. 792, eff. 1-1-22; correction in (2) (a) 1. made under s. 35.17, Stats., Register December 2021 No. 792, eff. 1/1/2022