Section 812.13. Drilled wells terminating in unconsolidated formations, i.e., usually sand or gravel or both.

  Unconsolidated formation wells shall be constructed according to the requirements in s. NR 812.12 and as follows:

(1)   General requirements.

(a) The minimum diameter for all drilled wells in unconsolidated formations, based on nominal size of well casing pipe is:

1. For nonpotable high capacity wells and for low capacity wells, except school and wastewater treatment plant wells, a minimum diameter of: 2 inches when steel well casing pipe is used, 4 inches when thermoplastic well casing pipe is used.

2. For potable high capacity, school and for wastewater treatment plant wells a minimum diameter of 4 inches.

(b) The minimum well casing pipe depth for all drilled wells in unconsolidated formations, not including any screen, is:

1. For nonpotable high capacity wells and for low capacity wells, except school and wastewater treatment plant wells, a minimum depth of 25 feet or 10 feet below the static water level, whichever is greater.

2. For potable high capacity and school wells, and for wastewater treatment plant wells when there is no treatment pond or lagoon or sludge bed on the wastewater treatment plant property, a minimum depth of 60 feet below the ground surface or 20 below the static water level, whichever is greater.

3. For wastewater treatment plant wells when there is a treatment pond or lagoon or sludge bed on the wastewater treatment plant property, a minimum depth of 100 feet below the ground surface or 20 feet below the static water level, whichever is greater.

(c) The pump intake shall be set at least 5 feet above the bottom of the well casing pipe and shall be set such that the pump does not break suction under normal operating conditions.

(d) Steel and thermoplastic well casing pipe, as specified in s. NR 812.17 , may be used for low capacity wells and for nonpotable high capacity wells, but not including school and wastewater treatment plant wells. Only steel well casing pipe may be used for potable high capacity, school and wastewater treatment plant wells.

(e)

1. An adequate screen shall be provided where necessary to prevent sand pumping conditions. The required types and materials for screens are:

a. For potable low capacity wells, a continuous-slot screen composed of stainless steel, everdur, monel, brass or approved polyvinyl chloride (PVC). Noncontinuous-slot screens may be used if approved.

aj. Criteria on which noncontinuous-slot screen approvals are based includes, but is not limited to, type and composition of screen material, spacing and evenness of cuts of screen slots and cleanliness of the screen and screen slots.

ap. Screen selection for driven-point wells is optional, except that screens having any lead content may not be used.

b. For nonpotable high capacity wells, not including dewatering wells, a continuous-slot screen meeting the requirements of subd. 1. a. or a low carbon steel or galvanized-steel, continuous-slot screen.

c. For potable high capacity wells, a continuous-slot screen, v-shaped, wire-wrap on a rod base type; composed of stainless steel, everdur, monel or brass. The brass may not have a lead content of more than 8%.

d. For nonpotable low capacity wells and dewatering wells, screens are not required; if used, screen selection is optional, except that screens having any lead content may not be used.

2. Screen installation may be accomplished by permanently welding or threading the screen onto the bottom of the well casing pipe, by placement of the screen in the bottom of the well casing pipe and pulling back the casing (telescope method), by the wash-down method, the jetting method or the bail-down method. A small diameter drill stem, rod or bit or a small diameter pipe column may be used to hold the screen down with the telescope method.

3. A riser pipe may be installed to extend upward from the top of the screen. The riser pipe material may be thermoplastic or metal providing the metal does not have a lead content in excess of 8%.

4. A packer shall be used to provide a sand seal between the bottom of a well casing pipe and the top of a screen. Lead packers may not be used. Packers used to retain grout or reduce water flow shall be made of durable, nontoxic material. Burlap packers may not be used.

5. Materials having a lead content greater than 8% by weight, may not be installed in a well. Component parts of manufactured products containing lead shall not have a lead content of more than 5% of the total product weight. “Lead wool" or other products containing more than 8% lead may not be used as seals in the bottom of open-ended well casing pipes or as screens terminating in coarse formations.

(f) Gravel-pack well construction shall comply with the additional requirements of s. NR 812.16 .

(g) Wells constructed by auguring or jetting methods shall be constructed according to the requirements for percussion methods of sub. (2) .

(2)   Percussion method requirements for drilled wells in unconsolidated formations.

(a) When steel well casing pipe is installed in a drilled unconsolidated formation well using percussion methods, the well shall be drilled as follows:

1. An upper enlarged drillhole constructed by percussion methods shall be constructed to the minimum depth required in Tables I-IV. The well casing pipe may be driven from the surface without the use of an upper enlarged drillhole when there is a caving formation at the surface extending to 10 feet or deeper or when granular bentonite of the 8-mesh size is either mounded around the top of the well casing pipe or placed in a starter drillhole and allowed to follow the well casing pipe down during driving. If granular bentonite is not used, an upper enlarged drillhole shall be constructed when a noncaving material, usually clay, silt or hardpan, is encountered in the top 10 feet. Rotary-air methods as specified in s. NR 812.12 (19) may be used to construct the upper enlarged drillhole. It shall be at least 4-inches larger in diameter than the nominal diameter of the well casing pipe for nonpotable high capacity wells and for low capacity wells, except school and wastewater treatment plant wells. When steel well casing pipe assembled with welded joints is used and the annular space sealing material is placed with an approved pressure method, the diameter may be reduced to 2 inches larger than the nominal well casing pipe diameter. The upper enlarged drillhole shall be 3 inches larger in diameter than the outside diameter of the permanent well casing pipe or casing couplings for potable high capacity, school and wastewater treatment plant wells. When the near surface material is of a caving nature, the upper enlarged drillhole shall be constructed by driving, while drilling, a temporary outer casing. The upper enlarged drillhole shall be kept filled up to within 10 feet of the ground surface with clay slurry or sodium bentonite slurry having a mud weight of at least 11 pounds per gallon or with granular bentonite throughout the driving of the permanent steel well casing pipe. If the upper enlarged drillhole extends below the 40-foot depth, the slurry shall be placed with a conductor pipe. If any of the annular space seal settles during development of the well, it shall be replaced following development.

2. Following driving of the well casing pipe any upper enlarged drillhole shall be filled with clay or sodium bentonite slurry having a mud weight of a least 11 pounds per gallon or with neat cement grout, except only neat cement grout may be used for potable high capacity, school or wastewater treatment plant wells. Neat cement grout shall be placed according to s. NR 812.20 . If the upper enlarged drillhole extends below the 40-foot depth and the annular space sealing material is clay or sodium bentonite slurry, the sealing material shall be placed with a conductor pipe. When temporary outer casing pipe is used, it shall be removed during or following the sealing process. If the upper enlarged drillhole extends below the 100-foot depth, the annular space sealing material shall be placed with an approved pressure method as specified in s. NR 812.20 . If any of the annular space seal settles during or following development of the well, it shall be replaced.

3. When using a rotary machine with hammer or a casing hammer for percussion methods, the drill cuttings inside and just below the well casing pipe may be removed with a rotary bit with the use of air.

(b) Thermoplastic well casing pipe may be used when percussion methods are used to drill wells in unconsolidated formations under the following conditions:

1. Thermoplastic well casing pipe may only be used for nonpotable high capacity wells and for low capacity wells, developed in unconsolidated formations and constructed in accordance with line A or B of Table I but not including school or wastewater treatment plant wells.

2. Thermoplastic well casing pipe may only be used for wells where the annular space is sealed with sodium bentonite or clay slurry. Cement grout may not be used. The thermoplastic well casing pipe shall be set in an upper enlarged drillhole constructed within a temporary outer steel well casing at least 4 inches larger in diameter than the nominal diameter of the permanent well casing pipe. The temporary outer casing and upper enlarged drillhole shall extend to the full depth of the well casing pipe if constructed with percussion methods. The temporary outer casing pipe shall be removed after setting the well casing pipe. During removal, the annular space shall be filled with clay or sodium bentonite and cuttings slurry with a mud weight of at least 11 pounds per gallon. The bottom of the temporary outer casing shall remain submerged in the slurry throughout the removal. If the upper enlarged drillhole extends below the 40-foot depth, the slurry shall be placed with a conductor pipe. If any of the annular space seal settles during development of the well, it shall be replaced following development.

3. The well casing pipe may not be driven, pushed or forced into the formation or into the upper enlarged drillhole, but the well casing pipe may be pulled back to expose a screen.

4. Drilling tools such as drill bits or stabilizers may not be placed in the well casing pipe nor may any drilling or reconstruction occur after placement of the well casing pipe in the well. This restriction does not preclude the installation or replacement of telescoping screens.

5. Screens may be installed as specified in s. NR 812.13 (1) (e) 2. If a screen is not permanently attached, an approved packer shall be used to seal the space between the screen and the well casing pipe. A small diameter drill stem, bit or rod or a small diameter pipe column bearing on the screen bottom plate may be used to hold the screen down with the telescope method.

6. If the thermoplastic well casing pipe extends above the frost line, the upper terminus of the well shall be contained in a well house or in a capped oversized steel well casing pipe. The pipe shall extend from the top of the thermoplastic well casing pipe to a depth below the frost level.

(3)   Rotary method requirements for drilled wells in unconsolidated formations.

(a) When steel well casing pipe is installed in a drilled unconsolidated formation well using rotary methods, the well shall be drilled as follows:

1. An upper enlarged drillhole shall be constructed and maintained at full diameter by circulating drilling mud to the required depth of well casing pipe setting, as specified by Tables I to IV. The well casing pipe shall be set concentrically in the upper enlarged drillhole. The annular space between the upper enlarged drillhole and the permanent well casing pipe shall be permanently sealed with sodium bentonite and cuttings slurry having a mud weight of at least 11 pounds per gallon or with neat cement grout, except that only neat cement grout may be used for potable high capacity, school and wastewater treatment plant wells. If any of the annular space seal settles during or following development of the well, it shall be replaced so as to seal the entire annular space.

2. The upper enlarged drillhole may be constructed less than 4 inches larger in diameter than the nominal diameter of the well casing pipe, but shall be at least 2 inches larger in diameter than the nominal diameter of the well casing pipe only if the following conditions are met:

a. The well is to be a nonpotable high capacity well or is to be a low capacity well, except a school or wastewater treatment plant well,

b. The required sealing material, according to Tables I to IV, is placed in the annular space between the upper enlarged drillhole and the well casing pipe using an approved pressure method according to the requirements of s. NR 812.20 , and

c. The well casing pipe is assembled entirely with welded joints.

3. For potable high capacity, school and wastewater treatment plant wells, an upper enlarged drillhole at least 3 inches larger in diameter than the outside diameter of the permanent well casing pipe or the outside diameter of the well casing couplings, if used, shall be constructed and maintained at full diameter by circulated drilling mud to the depth as required by Tables III and IV. The annular space shall be sealed with neat cement grout according to the requirements of s. NR 812.20 .

4. Temporary outer casing may be used to hold the upper enlarged drillhole open only if it is removed during the final sealing of the annular space. An upper enlarged drillhole may be constructed to accommodate the setting and removal of the temporary outer casing if the drillhole is constructed and maintained at full diameter by circulating drilling mud and is at least 2 inches larger in diameter than the nominal diameter of the temporary outer casing assembled with welded joints.

5. If necessary the well casing pipe may be driven deeper so as to develop a deeper portion of the aquifer. The annular space of the well shall be completely filled with drilling mud and cuttings during such driving. This method may also be used for any reason when the upper enlarged drillhole is constructed to at least the 40-foot depth.

(b) Thermoplastic well casing pipe may be used when rotary methods are used to drill wells in unconsolidated formations under the following conditions:

1. Thermoplastic well casing pipe may only be used for nonpotable high capacity wells and for low capacity wells, except school and wastewater treatment plant wells.

2. Thermoplastic well casing pipe may only be used for wells developed in unconsolidated formations and constructed in accordance with line A or B of Table I.

3. Thermoplastic well casing pipe may not be driven, pushed or forced into the formation or into the upper enlarged drillhole except that the well casing pipe may be pulled back to expose a screen.

4. An upper enlarged drillhole at least 4 inches larger in diameter than the nominal diameter of the thermoplastic well casing pipe shall be constructed and maintained at full diameter by circulating drilling mud to the required depth of well casing pipe settings, as specified in Tables I to IV. The thermoplastic well casing pipe shall be set concentrically in the upper enlarged drillhole full of drilling mud. The drilling mud shall have a mud weight of at least 11 pounds per gallon. If any of the annular space seal settles during or following development of the well, it shall be replaced so as to seal the entire annular space.

5. 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 preclude the installation or replacement of screens.

6. Screens may be installed as specified in s. NR 812.13 (1) (e) 2. If a screen is not permanently attached, an approved packer shall be used to seal the space between the screen and the thermoplastic well casing pipe. A small diameter drill stem or rod or small diameter pipe column bearing on the screen bottom plate may be used to place the screen with the telescope method.

7. If the thermoplastic well casing pipe extends to above the ground surface, the upper terminus of the well may be contained in a well house or in a capped oversized steel casing pipe which extends from the top of the thermoplastic well casing pipe to a depth below the frost level.

History: Cr. Register, January, 1991, No. 421 , eff. 2-1-91; am. (2) (a) 2., (b) 1., (3) (a) 1. and (b) 4., Register, September, 1994, No. 465 , eff. 10-1-94; correction in (2) (e) 1., made under s. 13.93 (2m) (b) 1., Stats., Register, September, 1996, No. 489 CR 13-099 : am. (3) (b) 7., Register September 2014 No. 705 , eff. 10-1-1.

Note

The department may grant variances to the 5 foot requirement in low permeability, low yielding formations. Microsoft Windows NT 6.1.7601 Service Pack 1 Louvered, shutter-type screens may be used for gravel-pack well construction as specified in s. NR 812.16 (3) . Microsoft Windows NT 6.1.7601 Service Pack 1 The department will review applications for approval of new types of screens and new materials for screens as such products are developed. Microsoft Windows NT 6.1.7601 Service Pack 1