Section 812.20. Grouting and sealing.

 

(1)   Grouting and sealing materials.

(a) Neat cement grout. Neat cement grout shall consist of a mixture of cement and water in the proportion of one bag of Portland cement, 94 pounds, ASTM C 150, Type I or API-10A, Class A; and 5 to 6 gallons of clean water from a known safe and uncontaminated source. Powdered bentonite may be added up to a ratio of 5 pounds per 94-pound bag of cement. Ingredients, to increase fluidity, control shrinkage or time of set may be used only with approval. Neat cement grout shall be used to seal the annular space:

1. Of low capacity wells when the upper enlarged drillhole is constructed more than 5 feet into a bedrock formation,

2. Of low capacity bedrock wells when bedrock is encountered within 40 feet of the ground surface or within 30 feet of the ground surface if the bedrock is sandstone,

3. Of potable high capacity wells,

4. Of school wells,

5. Of wastewater treatment plant wells,

6. When a liner pipe is installed for the purpose of preventing water containing contaminants with levels exceeding the drinking water standards of s. NR 812.06 from entering the well.

7. Of heat exchange drillholes if potable water or an approved fluid is continuously circulated in the loop pipe until heat of hydration subsides to a safe level below the temperature of potential loop pipe deformation.

(b) Concrete (sand-cement) grout. Concrete (sand-cement) grout shall consist of a mixture of cement, sand and water in the proportion of one bag of Portland cement, 94 pounds, ASTM C 150, Type I or API-10A, Class A; a cubic foot of dry sand and 5 to 6 gallons of clean water from a known safe and uncontaminated source. The sand shall meet the specifications for use in Portland cement concrete. Concrete (sand-cement) grout shall be placed with a conductor (tremie) pipe. Approval is required for the use of concrete grout. Approval for the use of concrete grout may be granted when an excessive loss of circulation in grouting with neat cement grout occurs.

(c) Sodium bentonite water slurry (drilling mud and cuttings). Sodium bentonite water slurry (drilling mud and cuttings). A sodium bentonite water slurry (drilling mud and cuttings) may be used as sealing material in unconsolidated formation wells or bedrock wells, provided depth to a bedrock formation or other well construction requirements in Tables I to IV do not specify the use of neat cement grout and the well is not a potable high capacity, school or wastewater treatment plant well. A mud weight of at least 11 pounds per gallon is required. Normal drilling mud circulated during the construction of wells may not meet this requirement for sealing unless additional drill cuttings are added to the slurry. Sodium bentonite water slurry (drilling mud and cuttings) is not allowed for grouting of heat exchange drillholes.

(d) Clay slurry. Clay slurry is a fluid mixture of water, clean native or approved commercial clay; and drill cuttings. Clay slurry may be used as an annular space sealing material for low capacity wells constructed with percussion methods, except for bedrock wells where the upper enlarged drillhole extends more than 5 feet into the bedrock or when the bedrock is encountered at a depth of less than 40 feet, 30 feet for sandstones and except for school and wastewater treatment plant wells. The clay slurry shall have a mud weight of at least 11 pounds per gallon. Clay slurry is not allowed for grouting of heat exchange drillholes.

(e) Sodium bentonite. A sodium bentonite grout may be used as a sealing material for heat exchange drillholes, if a minimum of a 20 percent solids mixture is maintained as per manufacturer specifications.

(f) Sodium bentonite (bentonite-sand) grout. Sodium bentonite grout may be mixed with clean silica sand up to a ratio of a 5 to 1 mixture of silica sand to bentonite grout, for grouting heat exchange drillholes. Higher mix ratios must receive prior approval from the department before being used. Clean silica sand shall consist of silica sand with 80 percent or more of the sand smaller than 0.0117 inch (passing U.S. Sieve #50) in size.

(g) Cement (cement-bentonite) grout. A cement (cement-bentonite) premix product may be used as a sealing material for heat exchange drillholes if it is approved by the department before being used. Drillers shall not mix their own ratio.

(h) Carbon (carbon-bentonite) grout. A carbon-bentonite premix product may be used as a sealing material for heat exchange drillholes if it is approved by the department before being used. Drillers shall not mix their own ratio.

(2)   Cement grouting procedure requirements. The approved cement grouting procedure is as follows:

(a) Neat cement grout shall be placed from the bottom of the open annular space up to the ground surface using one of the methods described in sub. (3) .

(b) Conductor (tremie) pipe used for cement grouting shall be any of the following:

1. Metal pipe,

2. Rubber-covered hose reinforced with braided fiber or steel and rated for at least 300 psi, or

3. Thermoplastic pipe rated for at least 100 psi including:

a. Polyvinyl chloride (PVC),

b. Chlorinated polyvinyl chloride (CPVC),

c. Polyethylene (PE),

d. Polybutylene (PB), and

e. Acrylonitrile butadiene styrene (ABS).

(c) The grout shall be placed in one continuous operation, if possible. I t i s the well or heat exchange drille r ' s or well constructo r ' s responsibility to ensure that all necessary materials are on the job site. I f unfore seen circumstances prevent completing the cement grouting work in one continuous operation, the well or heat exchange driller or well constructor shall report the non-continuous grouting operation and the reason for it on the construction report for the well.

(d) When a conductor (tremie) pipe is used, the bottom end shall be kept submerged in the grout throughout the grouting process.

(e) The grout shall be brought up to the ground surface. The density of the grout flowing from the annular space at the ground surface shall be the same as the density of the grout being placed. Any settling of the grout more than 6 feet below the ground surface shall be made up. The well driller or well constructor shall add grout until it comes back up to the ground surface.

(f) When temporary outer casing is used to construct the upper enlarged drillhole an attempt shall be made to remove the temporary outer casing during or after the grouting process. If possible, it shall be removed. The grout level shall be retained above the bottom of the casing during removal of the casing.

(g) When an upper enlarged drillhole has been constructed to accommodate the setting and removal of temporary outer casing, the annular space between the temporary outer casing and the well casing pipe shall be grouted before the temporary outer casing is pulled. After the grout between the temporary outer casing and the well casing pipe flows at the ground surface the annular space outside the temporary outer casing shall be grouted by placing a tremie pipe to the bottom of the outer annular space. The grout shall flow at the ground surface before the temporary outer casing is pulled.

(h) The well driller or well constructor shall allow the grout to set for at least 12 hours before commencing further well construction.

(i) Prior approval is required for the use of the “Halliburton" grouting methods and the “grout displacement" grouting method when the upper enlarged drillhole is more than 200 feet deep or when drilling mud or bentonite slurry has not been circulated up to the ground surface in the annular space prior to grouting.

(j) The “conductor (tremie) pipe-gravity" method is not an approved pressure method of grouting. All other methods described in sub. (3) are approved pressure methods for cement grouting and sealing and shall be used when neat cement grout is required to seal the annular space when the upper enlarged drill- hole is less than 4 inches larger in diameter than the nominal diameter of the well casing pipe or when the upper enlarged or heat exchange drillhole extends greater than 25 feet deep or when the heat exchange drillhole is less than 25 feet deep.

(3)   Cement grout placement methods. This subsection describes approved cement grout placement methods.

(a) Conductor (tremie) pipe-gravity. As depicted in figure 11, grout material may flow by gravity through a funnel or hopper connected to a conductor pipe. The conductor (tremie) pipe shall be lowered to the bottom of the annular space to be grouted and the grout material placed from the bottom up. The end of the conductor pipe shall be kept submerged in the grout at all times. This method may be used only when the upper enlarged drillhole is at least 4 inches larger in diameter than the nominal diameter of the well casing pipe and is less than 100 feet deep or when the heat exchange drillhole is less than 25 feet deep. The grout shall flow at the surface with the same consistency as the grout entering the well.

(b) Conductor (tremie) pipe-pumped. As depicted in figure 12, the grout material shall be placed by a pump through a conductor pipe into the annular space between the well casing pipe and the upper enlarged drillhole wall or inside surface of the temporary outer casing or a heat exchange drillhole. The minimum diameter of the upper enlarged drillhole shall be as specified in Tables I to IV. The conductor pipe shall be lowered to the bottom of the annular space to be grouted and the grout material shall be pumped from the bottom up. The end of the conductor pipe shall be kept submerged in the grout at all times and the conductor pipe shall be maintained full of grout. The grout shall flow at the surface with the same consistency as the grout entering the well.

(c) Grout (float) shoe-continuous injection. As depicted in figure 13, the bottom of the well casing pipe shall be fitted with a grout (float) shoe equipped with a back pressure (check) valve. A conductor pipe or drill stem shall be connected to the grout shoe and shall extend up through the well casing pipe to a grout pump at the ground surface. The well casing pipe shall be suspended a short distance above the bottom of the upper enlarged drillhole. Grout material shall be pumped through the conductor pipe and the grout shoe until the entire annular space is filled with grout. The conductor pipe or drill stem shall then be removed. The well casing pipe shall be set to the bottom of the upper enlarged drillhole. The grout material shall be allowed to set for at least 12 hours. Once set, the grout shoe and back pressure valve may be drilled out and the well construction continued.

(d) Well seal/tremie pipe-pumped (Braden-head method). As depicted in figure 14, the well casing pipe shall be suspended a short distance above the bottom of the upper enlarged drillhole. The well casing pipe and annulus shall be filled with water, drilling mud or bentonite slurry. A conductor (tremie) pipe shall be set inside the well casing pipe to the bottom and shall extend watertight through a sanitary well seal installed securely in the top of the well casing pipe. A packer may be installed inside the well casing pipe, at depth, as an alternative to using a well seal at the top. The grout shall be pumped down the conductor pipe and up the annular space. The grout shall flow at the surface with the same consistency as the grout entering the top of the conductor pipe. Immediately following grout flow at the surface, the well casing pipe shall be set to the bottom of the upper enlarged drillhole of an unconsolidated formation well or driven to a firm seat in a bedrock well.

(e) Halliburton (double plug) method. This method may only be used when the upper enlarged drillhole is less than or equal to 200 feet deep or when drilling mud or bentonite slurry has been circulated in the upper enlarged drillhole from the bottom up to the ground surface prior to grouting. The grout shall be placed as follows: As depicted in figure 15, the well casing pipe casing shall be suspended a short distance above the bottom of the upper enlarged drillhole. A drillable spacer plug shall be inserted into the well casing pipe and the top of the well casing pipe sealed watertight. A measured volume of grout, calculated to be of adequate quantity to seal the annular space, and to fill the bottom 10 to 15 feet of well casing pipe shall be pumped into the well casing pipe through a small diameter pipe extending watertight through the well seal. The well casing pipe shall then be opened and a second plug inserted on top of the grout and the top of the well casing pipe resealed. A measured volume of water, calculated to fill the well casing pipe except for the bottom 10 to 15 feet, shall be pumped into the well casing pipe, pushing the second plug to within 10 to 15 feet above the bottom of the well casing pipe and pushing most of the grout from the bottom of the well casing pipe up into the annular space. As an alternative, a drill stem may be used to push the top plug down to near the bottom of the well casing pipe. For this alternative, the plug may not be attached to the drill stem. If the bottom plug used is longer than the gap between the bottom of the suspended well casing pipe and the bottom of the upper enlarged drillhole, it is not necessary to pump in a measured volume of water. A conductor (tremie) pipe shall be available at the drill site in case the grout does not flow at the ground surface. The water pressure in the well casing pipe shall be maintained for 12 hours until the grout has set and before well construction may continue.

(f) Halliburton (single plug) method. This method may only be used for wells when the upper enlarged drillhole is less than or equal to 200 feet deep or when drilling mud or bentonite slurry has been circulated in the upper enlarged drillhole from the bottom up to the ground surface prior to grouting. As depicted in figure 16, the grout shall be placed as follows: The well casing pipe shall be suspended a short distance above the bottom of the upper enlarged drillhole. A measured volume of grout, calculated to seal the annular space and to fill the bottom 10 to 15 feet of well casing pipe shall be pumped into the well casing pipe through a small diameter pipe extending watertight through the well seal. A drillable spacer plug shall be inserted into the well casing pipe and the top of the well casing pipe sealed watertight. A measured volume of water, calculated to fill the well casing pipe except for the bottom 10 to 15 feet shall be pumped into the well casing pipe, pushing the plug down to about 10 to 15 from the bottom of the well casing pipe and most of the grout from the bottom of the well casing pipe up into the annular space. A landing collar should be installed near the bottom of the well casing pipe to prevent the plug from being forced out the bottom. As an alternative a drill stem may be used to push the plug down. For this alternative the plug may not be attached to the drill stem. If the plug used is longer than the gap between the bottom of the suspended well casing pipe and the bottom of the upper enlarged drillhole, it is not necessary to pump in a measured volume of water. A conductor (tremie) pipe shall be available at the drill site in case the grout does not flow at the ground surface. The water pressure in the well casing pipe shall be maintained for 12 hours until the grout has set and before well construction may continue.

(g) Grout displacement method. This method may only be used for wells when the upper enlarged drillhole is less than or equal to 200 feet deep or when drilling mud or bentonite slurry has been circulated in the upper enlarged drillhole from the bottom up to the ground surface prior to the grouting. As depicted in figure 17, a measured volume of grout calculated to be of adequate quantity to seal the annular space plus at least 15% of that volume shall be placed into the upper enlarged drillhole through a conductor (tremie) pipe. The well casing pipe shall be fitted with centering guides and a drillable plug at the bottom and shall be lowered through the grout to the bottom of the upper enlarged drillhole allowing the grout to be forced up into the annular space. If necessary, pressure shall be applied and maintained on the top of the well casing pipe to hold it in place for at least 12 hours or until the grout sets. Water may be added to the well casing pipe to provide extra weight. If the grout does not flow at the ground surface the remainder of the annular space shall be filled with grout placed through a conductor pipe that shall be at the drill site.

- See PDF for diagram Figure 11. Conductor (tremie) pipe-gravity method for neat cement grouting.

- See PDF for diagram Figure 12. Conductor (tremie) pipe-pumped method for neat cement grouting.

- See PDF for diagram Figure 13. Grout (float) shoe-pumped method for neat cement grouting.

- See PDF for diagram Figure 14. Well seal/conductor (tremie) pipe-pumped (Braden-Head) method for neat cement grouting.

- See PDF for diagram Figure 15. Halliburton (double plug) method for neat cement grouting.

- See PDF for diagram Figure 16. Halliburton (single plug) method for neat cement grouting.

- See PDF for diagram Figure 17. Grout displacement method for neat cement grouting.

- See PDF for diagram Figure 18. Street elbow method for neat cement grouting.

(h) Street elbow method. As depicted in figure 18, a small diameter hole is cut through the wall of the well casing pipe near the bottom of the string of well casing pipe. A street elbow is welded watertight through this hole. The male end of the street elbow extends out into the annular space. A ball check valve is threaded into the female end of the street elbow inside the well casing pipe. The top threads on the check valve are “left-handed". A string of conductor (tremie) pipe is threaded into the top of the check valve. The entire string of well casing pipe and conductor pipe are set to the bottom of the upper enlarged drillhole. The grout is pumped down through the conductor pipe and up into the annular space. The grout must flow at the surface with the same consistency as the grout entering the conductor pipe. Immediately following grouting, the conductor pipe is screwed out of the left-hand thread of the check valve and removed. The check valve prevents the grout from moving back inside the well casing pipe. After the grout has set, the drill stem is lowered to the bottom of the inside of the well casing pipe to knock the street elbow off the well casing pipe before well construction continues.

(4)   Sodium bentonite water slurry placement methods. When neat cement grout is not required in Tables I to IV and is not to be used, the annular space between any upper enlarged drillhole and the well casing pipe shall be sealed as follows:

(a) When percussion methods are used, following completion of the driving of the well casing pipe, a clay or sodium bentonite and cuttings slurry with a mud weight of at least 11 pounds per gallon shall be placed to permanently fill and seal the annular space. Any subsidence shall be made up. If the upper enlarged drillhole extends below the 40-foot depth, the slurry shall be placed with a conductor pipe.

(b) When rotary methods are used, after the upper enlarged drillhole has been completed by circulating drilling mud, the slurry coming out the top of the annular space shall have a mud weight of at least 11 pounds per gallon before the well casing pipe is set in the drillhole. Any subsidence of the drilling mud and cuttings in the annular space shall be made up. The annular space shall remain filled and sealed up to the ground surface. The rotary method of circulating drilling mud during construction described in this paragraph is an approved pressure method for placing sodium bentonite slurry or drilling mud and cuttings and shall be used when required in Tables I to IV and ss. NR 812.13 to 812.15 .

History: Cr. Register, January, 1991, No. 421 , eff. 2-1-91; am. (3) (c), (4) (a) and (b), Register, September, 1994, No. 465 , eff. 10-1-94; CR 13-096 : cr. (1) (a) 7., am. (1) (c), (d), cr. (1) (e) to (h), am. (2) (c), (j), (3) (a), (b) Register September 2014 No. 705 , eff. 10-1-14.