NR 812.14(3)(d)(d) Screens. Screens may be installed in loosely cemented sandstone wells. The requirements for screen materials and installation of the screen specified in s. NR 812.13 (4) and the requirements for gravel packs specified in s. NR 812.16 apply to drilled wells in bedrock formations. NR 812.14(3)(e)(e) Thermoplastic casing use restricted. Thermoplastic casing may only be placed in an upper enlarged drillhole and may not terminate in crystalline bedrock or be driven or jetted into place. NR 812.14(3)(f)(f) Damaged or deformed thermoplastic casing. A well using thermoplastic casing terminating in bedrock shall be free of cracks and free of deformation and the inside diameter shall remain within manufacturer’s specifications after construction or reconstruction. A failed well constructed with thermoplastic casing shall have the casing removed or drilled out prior to filling and sealing. NR 812.14(3)(g)(g) Drilling tool use restricted. Drilling tools such as drill bits or stabilizers may not be placed in the thermoplastic well casing pipe nor may any drilling or reconstruction occur after placement of the well casing pipe in the well. This restriction does not prohibit the insertion of equipment for the development and cleaning of wells. NR 812.14(4)(4) Driving or advancing casing. A well driller or well constructor may drive or mechanically advance steel casing from the ground surface to the top of bedrock when the depth to the top of bedrock is equal to the minimum casing depths under sub. (3) or deeper. When steel casing is driven or mechanically advanced to the top of bedrock, it shall be completed in accordance with all of the following: NR 812.14(4)(a)(a) Drive shoe. The casing shall be equipped with a drive shoe or casing shoe meeting the requirements specified in s. NR 812.11 (10). NR 812.14(4)(b)(b) Annular space sealing. Clay slurry, sodium bentonite slurry, or granular bentonite shall be maintained around steel casing during advancement using any of the following methods: NR 812.14(4)(b)1.1. When casing is driven or advanced from the ground surface, excavating a funnel-shaped depression around the casing to create a reservoir, which shall be kept filled with dry granular bentonite. The granular bentonite shall be kept dry at the surface during advancement. NR 812.14(4)(b)2.2. Filling a starter drillhole or temporary outer casing with clay slurry or sodium bentonite slurry and drill cuttings having a mud weight of at least 11 pounds per gallon, or with dry granular bentonite, which shall be maintained around the outside of the casing. NR 812.14(4)(b)3.3. Constructing an upper enlarged drillhole in accordance with sub. (5). The upper enlarged drillhole shall be kept filled to within 10 feet of the ground surface with clay slurry or sodium bentonite slurry and drill cuttings having a mud weight of at least 11 pounds per gallon, or with dry granular bentonite which shall be maintained around the outside of the casing. NR 812.14(4)(c)(c) Driving to a firm seat. Steel casing shall be driven or advanced to a firm seat into the top of bedrock. NR 812.14(4)(d)(d) Mechanically holding down thermoplastic casing. For a well constructed with thermoplastic casing, the casing may not be driven to a firm seat. However, the casing may be held down mechanically within an upper enlarged borehole during grouting to prevent the casing from floating. NR 812.14(5)(5) Upper enlarged drillhole. When a well is constructed with casing that extends 5 feet or more below the top of bedrock, an upper enlarged drillhole shall be constructed to the depth the casing is set. When a well driller or well constructor constructs an upper enlarged drillhole for any reason, it shall be constructed in accordance with all of the following: NR 812.14(5)(a)(a) Minimum diameter. The minimum diameter of an upper enlarged drillhole shall meet the following requirements: 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.