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.

NR 812.26(6)(f)(f) Drillholes completed in bedrock formations. Drillholes completed into bedrock formations shall be filled and sealed from the bottom up with neat cement grout, sand cement grout, bentonite chips, or bentonite pellets except bentonite chips are not allowed for wells and drillholes less than 3 inches in diameter.

NR 812.26(6)(g)1.1. Dug or bored wells shall have the cover removed and the top five feet of curbing or concrete wall removed. Rock curbing may be caved into the drillhole as the well is being sealed only if done in a manner to prevent bridging. The well shall be filled and sealed using clean clay or silt, clean native soil, bentonite chips or pellets, concrete, sand-cement grout, or neat cement grout if constructed in unconsolidated formations.

NR 812.26(6)(g)2.2. Dug or bored wells constructed partially or completely into bedrock shall be filled and sealed with neat cement grout, sand-cement grout, concrete, or bentonite chips or pellets to a point at least two feet above the top of the bedrock. The remainder of the well or drillhole may be filled and sealed using any of the materials listed in par. (c) 1.

NR 812.26(6)(g)3.3. Dug or bored wells 18 inches in diameter and smaller shall be filled and sealed by means of a tremie pipe, except when bentonite chips or pellets are used or when clean clay or silt or clean native soil is used and the dug or bored well is 25 feet deep or less.

NR 812.26(6)(h)(h) Heat exchange drillholes. The filling and sealing of heat exchange drillholes shall be completed according to all of the following requirements:

NR 812.26(6)(h)1.1. If the loops for a heat exchange drillhole have not been grouted in place and can be removed from the drillhole, the loops shall be removed before filling and sealing.

NR 812.26(6)(h)2.2. If the loop for a heat exchange drillhole has been grouted into the drillhole and cannot be removed, the loop shall be evacuated of all fluids and cement or bentonite grout shall be pumped into the loop. The loops may be left in place after grouting or may be cut off below ground surface.

NR 812.26(6)(i)(i) Flowing wells. Materials for filling and sealing a flowing well shall be neat cement or neat cement with approved additives to increase the grout density and shall meet the requirements of s. NR 812.11 (15). The flow of water at the ground surface from a flowing well shall be reduced or stopped prior to filling and sealing using one of the following methods:

NR 812.26(6)(i)1.1. Centering a tremie pipe in the drillhole or casing within an inflatable packer.

NR 812.26(6)(i)2.2. Extending the well casing to a height above the piezometric surface.

NR 812.26(6)(i)3.3. Placing chlorinated sand-free pea gravel in a bedrock well from the bottom of the well to no higher than 40 feet from the bottom of the casing pipe.