NR 812.14(5)(a)1.1. The upper enlarged drillhole shall be 4 inches greater than the nominal diameter of the casing when coupled joints are used. NR 812.14(5)(a)2.2. A well driller or well constructor may reduce the diameter of an upper enlarged drillhole to 2 inches greater than the nominal diameter of the casing when welded steel casing is used and the required sealing material, according to the requirements of sub. (7), is placed in the annular space between the upper enlarged drillhole and the well casing pipe using a pressure grouting method according to the requirements of s. NR 812.20. NR 812.14(5)(b)(b) Method of keeping hole open. A well driller or well constructor shall maintain an upper enlarged drillhole at full diameter during drilling by any of the following methods: NR 812.14(5)(b)1.1. Keeping the drillhole filled up to within 10 feet of the ground surface with drilling mud. NR 812.14(5)(b)4.4. Circulating air, air and water, or drilling foam when the drillhole is constructed through non-caving clay, silt, or hardpan. NR 812.14(5)(c)(c) Minimum depth. The minimum depth of an upper enlarged drillhole shall be one of the following: NR 812.14(5)(c)2.2. To the bottom of any clay formation, or 20 feet, whichever is less, when the casing is driven or advanced to the top of bedrock in accordance with sub. (4) (b) 3. NR 812.14(5)(c)3.3. For a well constructed using thermoplastic casing, to a depth not more than 5 feet into the top of firm limestone, dolomite, or shale. NR 812.14(5)(d)(d) Grouting. A well driller or well constructor shall grout an upper enlarged drillhole according to the requirements specified in sub. (7). NR 812.14(6)(6) Lower drillhole. A well driller or well constructor shall complete the drilling of a lower drillhole in accordance with all of the following: NR 812.14(6)(a)(a) The lower drillhole may not be constructed prior to grouting an annular space unless the casing is first driven to a firm seat in bedrock. NR 812.14(6)(b)(b) Drill cuttings may not fill an open annular space during the drilling of a lower drillhole, except when casing is driven or advanced to the top of bedrock in accordance with sub. (4) (b) 3. NR 812.14(6)(c)(c) Cement grout shall set for a minimum of 12 hours prior to drilling a lower drillhole. NR 812.14(7)(7) Grouting and sealing. A well driller or well constructor shall seal annular spaces using one of the pressure grouting methods specified in s. NR 812.20. Grouting material shall meet the requirements specified in s. NR 812.11 (15). A flowing well shall be grouted using the materials specified in s. NR 812.15. Potable high capacity wells shall be grouted using the materials specified in s. NR 812.152. A well driller or well constructor shall seal annular spaces with any of the following materials: NR 812.14(7)(a)(a) Sodium bentonite, sodium bentonite-sand, or a mixture of clay slurry or bentonite drilling mud and cuttings when the upper enlarged drillhole is less than or equal to 20 feet in depth. NR 812.14(7)(b)(b) Sodium bentonite, sodium bentonite-sand, neat cement or bentonite-cement when the upper enlarged drillhole extends less than 5 feet into the top of bedrock. NR 812.14(7)(c)(c) Neat cement or bentonite-cement when the upper enlarged drillhole extends 5 feet or more into the top of bedrock. NR 812.14(8)(8) Bentonite chips in fractured formations. A well driller or well constructor may use bentonite chips in an annular space when fractures, voids, or caverns are encountered that prevent the flow of grout at the surface. When bentonite chips are used by a well driller or well constructor to seal fractures in an annular space, the chips shall be placed in accordance with all of the following: NR 812.14(8)(a)(a) The upper enlarged drillhole shall be a minimum of 4 inches larger than the nominal diameter of the permanent casing and shall extend to the depth of any fractures, voids or caverns encountered greater than 20 feet below the ground surface. NR 812.14(8)(b)(b) The upper enlarged drillhole shall be free of drilling mud or cuttings. NR 812.14(8)(c)(c) Any bentonite chips placed below the water table shall be screened and poured in a manner that prevents bridging. NR 812.14(8)(d)(d) Any bentonite chips placed above the water table shall be hydrated using water meeting the requirements specified in s. NR 812.11 (14). NR 812.14(8)(e)(e) The volume of bentonite chips used shall be limited to the minimum needed to resume grouting according to the requirements specified in s. NR 812.20. NR 812.14(8)(f)(f) The number of bags or volume of chips used, the depth they were placed, and the reason they were needed shall be noted on the well construction report. NR 812.14(9)(9) Dual aquifer prohibition. Wells may not be constructed open to both an unconsolidated formation and a bedrock formation. NR 812.14(10)(10) Wells constructed into the maquoketa shale. Wells constructed or reconstructed to withdraw water from any of the aquifers beneath the Maquoketa Shale and the Niagara formations in the eastern part of the state shall be cased and grouted into the Maquoketa Shale formation except in areas designated by the department as special well casing pipe depth areas. If a liner is used to case off the Niagara formation, the Maquoketa Shale formation or both, it shall be installed and grouted in place in accordance with s. NR 812.21.