NR 812.12(17)(a)1. 1. A chlorine solution with a minimum of 100 mg/L of chlorine shall be used to disinfect wells and well drilling equipment and the disinfectant shall be prepared according to Table D.

NR 812.12(17)(a)2. 2. The disinfectant shall be dispersed throughout the entire water column in the well. The disinfectant shall also be brought into contact with the inside of the well casing pipe above the static water level.

NR 812.12(17)(a)3. 3. The disinfectant shall remain in the well for at least 2 hours except for emergency situations, when water is needed without delay. A contact time of at least 30 minutes shall be provided for emergency situations.

NR 812.12(17)(b) (b) Flushing. A well driller or well constructor shall thoroughly flush wells to remove the chlorine solution after disinfection.

- See PDF for table

Note: mg/L = milligrams per liter (parts per million)

NR 812.12 History History: CR 18-095: r. and recr. Register June 2020 No. 774, eff. 7-1-20; CR 21-070: am. (5) (b), cr. (5) (c) Register July 2022 No. 799, eff. 8-1-22.

NR 812.13 NR 812.13 Drilled wells terminating in unconsolidated formations. A well driller or well constructor shall construct wells terminating in unconsolidated material according to the requirements specified in s. NR 812.12 and all of the following:

NR 812.13(1) (1) Minimum diameter. The minimum diameter for all drilled wells in unconsolidated formations, based on nominal size of well casing pipe, is 2 inches.

NR 812.13(2) (2) Casing depth. Minimum casing depths shall be measured from the ground surface. The minimum well casing pipe depth for all drilled wells in unconsolidated formations, not including any screen, is 25 feet or 10 feet below the static water level when the static water level is greater than 15 feet below ground surface.

NR 812.13(3) (3) Casing material and installation.

NR 812.13(3)(a) (a) Steel or thermoplastic well casing pipe, as specified in s. NR 812.11 (6) or (7), shall be used for low capacity wells and nonpotable high capacity wells.

NR 812.13(3)(b) (b) Thermoplastic casing may only be placed in an upper enlarged drillhole and may not be driven or jetted into place.

NR 812.13(3)(c) (c) 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 installation or replacement of screens, or the insertion of equipment for the development and cleaning of wells with screens.

NR 812.13(4) (4) Screens. A well driller or well constructor shall install an adequate screen when necessary to prevent sand pumping conditions. Screens installed in a well shall meet the requirements of s. NR 812.11 (11). A well driller or well constructor shall install screens according to the following requirements:

NR 812.13(4)(a) (a) Screen installation shall be accomplished in a manner that prevents damage to the screen or casing and prevents material from bypassing the well screen.

NR 812.13(4)(b) (b) A packer or shale trap may be used to provide a sand seal between the bottom of a well casing pipe and the top of a screen. Packers and shale traps shall meet the requirements of s. NR 812.11 (13).

NR 812.13(4)(c) (c) A riser pipe may be installed to extend upward from the top of the screen. The riser pipe material shall be thermoplastic or metal provided the metal does not have a lead content in excess of 0.25%.

NR 812.13(5) (5) Gravel Packs. The construction of a gravel pack well shall comply with the additional requirements specified in s. NR 812.16.

NR 812.13(6) (6) Driving or advancing steel well casing. A well driller or well constructor shall drive or advance casing according to the following requirements:

NR 812.13(6)(a) (a) The casing shall be equipped with a drive shoe or casing shoe meeting the requirements specified in s. NR 812.11 (10).

NR 812.13(6)(b) (b) Clay slurry, sodium bentonite slurry, or granular bentonite shall be maintained around the casing during advancement using any of the following methods:

NR 812.13(6)(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 812.13(6)(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 812.13(6)(b)3. 3. Constructing an upper enlarged drillhole in accordance with sub. (7). 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.

NR 812.13(7) (7) Upper enlarged drillhole. When an upper enlarged drillhole is constructed for any reason, it shall be completed in accordance with all of the following requirements:

NR 812.13(7)(a) (a) Minimum depth. The minimum depth of an upper enlarged drillhole shall be one of the following:

NR 812.13(7)(a)1. 1. To the final depth that the well casing is set.

NR 812.13(7)(a)2. 2. To the bottom of any clay formation, or 20 feet, whichever is less when the casing is driven or mechanically advanced as specified in sub. (6) (b) 3.