NR 812.26(5)(k)(k) Dewatering wells or drillholes. Well casing pipe may be removed from a dewatering well or a drillhole. The removed well casing pipe may only be reused for dewatering wells. NR 812.26(5)(L)(L) Gravel packs. When a well has a gravel pack that extends up to or within 20 feet of the ground surface, at least the top 20 feet of the gravel pack shall be jetted out or removed in some other manner. Once the gravel pack has been removed, the open annular space shall be filled and sealed with neat cement grout or concrete applied with a pressure method injected through a tremie pipe. NR 812.26(5)(m)(m) Well pits. When a well terminating in a pit is filled and sealed, the pit shall also be filled and sealed, except when the pit is an alcove or if the pit will only be used for the purpose of housing valves and the pit complies with s. NR 812.36 (1). The filling of a well pit shall meet all of the following requirements: NR 812.26(5)(m)1.1. All water system features shall be removed from the pit prior to filling and sealing. NR 812.26(5)(m)3.3. One wall of the pit shall be knocked out or perforated with several holes. NR 812.26(5)(m)4.4. The pit shall be filled and sealed with clean native soil less permeable than the soil surrounding the pit. NR 812.26(5)(n)(n) Nonpressurized conduits. When wells having nonpressurized conduits are filled and sealed, the basement end of the conduit shall be permanently sealed with a watertight cap or seal. NR 812.26(6)(a)(a) General. Once obstructions have been removed from a well or a drillhole, the well or drillhole shall be filled and sealed, from the bottom up with the use of a tremie pipe, except where the use of a tremie pipe is specifically exempted. As allowed in this section, all materials used to fill and seal wells and drillholes shall meet the specifications of s. NR 812.11 (15). NR 812.26(6)(b)(b) Use of bentonite chips or pellets. Bentonite chips or pellets may be used to fill and seal wells and drillholes, subject to all of the following restrictions: NR 812.26(6)(b)1.1. Bentonite chips may not be used for wells and drillholes less than 3 inches in diameter. NR 812.26(6)(b)2.2. The total depth may not be deeper than 500 feet and the number of feet of standing water in the well or drillhole may not be more than 350 feet. NR 812.26(6)(b)3.3. Bentonite chips or pellets may not be used for any well or drillhole filled with drilling mud or bentonite slurry. NR 812.26(6)(b)4.4. Any bentonite chips or pellets placed below the water table shall be screened and poured in a manner that prevents bridging. NR 812.26(6)(b)5.5. The depth of bentonite chips or pellets shall be monitored during the filling process, at a minimum of once every calculated 10 bags, to ensure the bentonite chips or pellets are not bridging in the well or drillhole. Any bridge of the bentonite chips or pellets shall be removed. NR 812.26(6)(b)6.6. After installing bentonite chips or bentonite pellets, clear water obtained from an uncontaminated source shall be poured into the well to hydrate the bentonite chips. Water shall be introduced until the water level rises to the top of the well casing and the well will not accept any additional water at the time the individual who performs the filling and sealing operation leaves the site. NR 812.26(6)(c)1.1. Drilled wells and driven point wells larger than 3 inches in diameter shall be filled and sealed with neat cement grout, sand-cement grout, concrete, bentonite chips, or bentonite pellets. NR 812.26(6)(c)2.2. Drilled wells and driven point wells less than or equal to 3 inches in diameter shall be filled and sealed with neat cement grout poured or pumped down the drive pipe or drillhole or by poured bentonite pellets. The use of a tremie pipe is not required. NR 812.26(6)(d)1.1. Drillholes less than 3 inches in diameter that extend below the water table shall be filled and sealed with bentonite pellets, or neat cement grout. NR 812.26(6)(d)2.2. Drillholes less than 3 inches in diameter that do not extend below the water table may be filled and sealed with granular bentonite. NR 812.26(6)(d)3.3. Drillholes 3 inches in diameter or greater shall be filled with drilling mud, cuttings, bentonite pellets, or bentonite chips to fill and seal the drillhole up to 10 feet below ground surface. From the existing ground surface to 10 feet below grade, the drillhole shall be filled with bentonite chips or pellets and hydrated with clear water obtained from an uncontaminated source. NR 812.26(6)(d)4.4. The top 18 inches near the surface may consist of asphalt, concrete, sand and gravel base coarse, or native soil. Sealing material in drillholes completed in agricultural areas may be terminated 30 inches below the ground surface and clean native soil may be placed on top of the settled sealing material to avoid interference with agricultural activities. NR 812.26(6)(e)1.1. Wells completed in bedrock formations shall be filled completely and sealed from the bottom up with neat cement grout, sand-cement grout, concrete, bentonite chips, or pellets except bentonite chips are not allowed for wells and drillholes less than 3 inches in diameter. NR 812.26(6)(e)2.2. Chlorinated sand-free pea gravel may be used to fill and seal an uncontaminated bedrock well deeper than 250 feet. Pea gravel may be poured without the use of a tremie pipe provided the well is sounded at 50-foot intervals to prevent bridging. When using pea gravel, the well shall be filled from the bottom up to 20 feet below the bottom of the casing pipe, or up to the 250-foot depth, whichever is deeper. NR 812.26(6)(e)3.3. When a well extends through the Maquoketa Shale formation, a neat cement grout, concrete, or bentonite chip or pellet plug at least 40 feet thick shall be placed and centered at the contact surface between the Maquoketa Shale and adjacent geologic formations, both above and below. When a well extends through the top of the uppermost Cambrian Sandstone formation or the top of the Eau Claire Formation of the Cambrian Sandstone, a neat cement grout, concrete, or bentonite chip or pellet plug at least 40 feet thick shall be placed and centered at the upper formation boundary whenever these layers are present in the open bedrock drillhole.