10 CSR 23-3.030 Standards for Construction of Wells PURPOSE: This rule describes the minimum standards for a properly constructed well but does not apply to community or noncommunity public water supply wells. It is the obligation and responsibility of the driller to construct community and noncommunity wells following procedures set forth by the Missouri Public Drinking Water rules.

PUBLISHER'S NOTE: The secretary of state has determined that the publication of the entire text of the material which is incorporated by reference as a portion of this rule would be unduly cumbersome or expensive. Therefore, the material which is so incorporated is on file with the agency who filed this rule, and with the Office of the Secretary of State. Any interested person may view this material at either agency's headquarters or the same will be made available at the Office of the Secretary of State at a cost not to exceed actual cost of copy reproduction. The entire text of the rule is printed here. This note refers only to the incorporated by reference material.

(1) Casing for Permanent Wells. Steel well casing used for the outside casing must be new and shall be of at least six-inch (6") nominal size (6.625 outside diameter in inches, actual dimensions), thirteen pounds (13 lbs.) per foot, 0.188 wall thickness. Coated casings are permitted as long as they are not a source of contamination to the groundwater. Larger diameter casing shall have minimum weights and thicknesses as specified in subsection (1)(G) of this rule. Concrete casing is permitted for use. Casing for permanent wells shall be of ferrous material, or where permitted by rule, plastic or concrete material. For ferrous pipe, the specifications and installation procedures are prescribed as follows. For plastic pipe, the specifications and installations procedures are prescribed in 10 CSR 23-3.070.

(A) Casing Joints. A protective well casing shall have watertight joints throughout its length. The joints shall be made by being continuously welded, threaded or other types of joints given written approval by the division. Tongue and groove type of joints are acceptable for concrete casings. Recessed or reamed and drifted couplings shall be used on threaded casing, or as an alternate, other couplings can be used but the design, taper and type of thread of the coupling shall match that of the pipe. Other casing design or materials shall be approved only by official written order of the division.

(B) Standard for Pipe. Pipe used as the casing in the permanent construction of a well shall be new pipe produced to recognized standards of the American Society for Testing and Materials, A53 grade A or B, A500 grade A or B, or A589 or other grade weldable new pipe having a quality equal to or greater than those specified. New pipe, when salvaged within thirty (30) days of the drilling of a well for water supply may be used as new pipe if still in new condition and must be decontaminated.

(C) Inside Casing Diameter. Under no condition shall the casing inside diameter be less than six inches (6") unless specifically exempted in 10 CSR 23-3 except for a driven well point or jetted well which shall be equipped with a casing pipe of at least one and one-fourth inches (1 1/4") inside diameter. The well shall also be of sufficient diameter to receive a pump or pumping apparatus of sufficient size to discharge the design capacity including anticipated decline in water levels.

(D) Vertical Extension. A well casing or its extension shall extend vertically at least one foot (1') above the finished surface grade. If the well is located in a floodplain see 10 CSR 23-3.010(1)(A)6. for requirements.

(E) A table of minimum specifications for steel casing for domestic, multifamily, high yield and unconsolidated material irrigation wells and bedrock irrigation wells follows: (A variance must be obtained in advance from the division to install casing not on this table.)

STEEL CASING TABLE

(2) Minimum Protective Depths of Well Casing. All wells shall be watertight to such depth as may be necessary to exclude contaminants. A well shall be constructed so as to seal off formations that are likely to pose a threat to the aquifer or human health. Requirements will be fulfilled to the minimum extent when the protective casing has been installed in conformity with the applicable construction set forth in 10 CSR 23-3.030 - 10 CSR 23-3.110. Sections (17)-(20) state the amount of grout needed to fill the minimum required amount of annular space in the different areas across Missouri. Where it is not feasible to follow the standards contained in this part, the permittee shall obtain approval of the division as to the design of the well before proceeding. The acceptability of the formation for well development shall be based on the satisfactory results of analysis of the water. Any water-bearing formation yielding water which is contaminated, as evidenced by the presence of chemicals or bacteria which may be harmful, shall be regarded as unsatisfactory for use as a potable supply unless adequate treatment is provided. The division will decide acceptable water treatment measures only after all well construction remedies have been exhausted.

(3) Grouting.

(A) Grouting Required for Wells. It is the obligation and responsibility of the well installation contractor to ensure that the annular space is sealed and that the casing does not leak. This obligation and responsibility ends three (3) years after the date of certification unless it can be shown that the well seal has been damaged by other persons. The following is a list of approved grouting methods:

1. Gravity installation method. The grout is poured into the annular space without the use of a tremie or grout pipe. Cement or bentonite slurry may never be poured through standing water without the use of a tremie pipe. The Gravity Grouting Table is a table which states the minimum requirements concerning the depth that grout can be gravity fed in wells that have an annulus from one inch to two inches (1"-2"). This table reflects the use of actual drill bit sizes and a six and five-eighths-inch (6 5/8") outside diameter casing. Nominal sizes may not be used when determining the annular space. Contact the division for instructions concerning grouting wells with larger than a two-inch (2") annulus. Note: When using plastic casing, a larger hole is recommended due to the belled casing ends reducing the annular space.

Gravity Grouting Table

Size Hole (inches)	Outside Diameter of Casing (inches)	Annular Space (inches)	Gravity Feed Depth (feet)
8 5/8 8 3/4 8 7/8 9 9 1/8 9 1/4 9 3/8 9 1/2 9 5/8 9 3/4 9 7/8 10 10 1/8 10 1/4 10 3/8 10 1/2 10 5/8	6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8 6 5/8	1 1 1/16 1 1/8 1 3/16 1 1/4 1 5/16 1 3/8 1 7/16 1 1/2 1 9/16 1 5/8 1 11/16 1 3/4 1 13/16 1 7/8 1 15/16 2	100 106 112 119 125 131 137 144 150 156 162 169 175 181 187 193 200

2. Tremie method. In this method the grout is placed in the annular space by gravity through a tremie or grout pipe suspended in the annular space. The tremie pipe is
placed into the annulus and extends to within five feet (5') from the bottom of the interval to be grouted. The grout is added into the tremie pipe which should remain submerged in the grouting material during the entire time the grout is being placed. The tremie pipe is gradually withdrawn as the grouting material is placed or may be removed after the annular space is full and before the grout sets;

3. Pressure grouting through tremie method. For this method the same procedure is followed as described in the tremie method, except the grout is pumped into the tremie pipe instead of placed by gravity flow;

4. Pressure grouting through the casing method. Instead of using a tremie pipe placed in the annular space a grout pump is attached to the top of the casing and grout pumped through the casing and allowed to fill the annular space from the bottom. Pumping continues until grout reaches the surface of the annular space. Grout must be allowed to set up before drilling continues;

5. Open-hole method. Grout is poured into the drill hole from the surface and allowed to fill the drill hole to the required level. Note: Much more grout is required to fill the bottom thirty feet (30') of drill hole when using the open-hole method. See 10 CSR 23-3.030(17)-(20) for specific amounts. Then the casing is placed into the drill hole through the grouting material. This method may not be used if water is standing in the drill hole unless grout is placed by one (1) of the tremie grouting methods or if bentonite chips are used, they must be allowed to completely hydrate before the casing is pushed into the grout;

6. Positive displacement method. Casing is set into the borehole to a point about five feet (5') above the casing point. Grout is poured into the well casing followed by a drillable plug. This is designed to push all grout to the bottom of the well. If there is water in the borehole and bentonite or cement slurry is used it must be emplaced via a tremie to the bottom of the borehole. The plug is pushed to the bottom of the casing forcing the grout down the inside of the casing and up the annular space. The casing is then set into the bottom of the drill hole; and

7. Other grouting methods must be approved by the division in advance.

(4) Approved Grouting Methods.

(A) Neat Cement Grout. Neat cement grout is a mixture of one (1) bag, ninety-four pounds (94 lbs.) of Portland cement (ASTM C150) to not more than six (6) gallons of clean water. Bentonite, up to six percent (6%) by weight of cement to reduce shrinkage or other additives (ASTM C688) to reduce permeability or control time of set or both, may be used. If bentonite is used, additional water should be added to the mix.

(B) Bentonite Grout. Sodium bentonite (swelling clay) is available in many forms from granules to pellets to chips. When grouting annular spaces with nonslurry bentonite, great care must be exercised to ensure the bentonite is placed properly. Flash swelling may occur and bridge off the annular space preventing an adequate seal when using powdered, granular, tablets or palletized bentonite. Therefore, only bentonite specifically designed to prevent flash hydration and to fall through standing water may be used. Chipped or pelletized bentonite may not be used in annular spaces less than one inch (1"). Bentonite must be applied slower than manufacturer's specifications. If there is no water in the annular space, the bentonite must be hydrated after each bag or water poured into the hole before application of the bentonite.

(C) Bentonite Slurry Grout. Sodium bentonite slurry grout is a bentonite/water mixture. There are many additives available that effect viscosity and set-up time. These additives are acceptable unless they are a potential contaminant. Bentonite slurry must have a solids content of at least twenty percent (20%).

(D) Other Grout Types. Other types of grout may be used when necessary if prior approval by the division is granted.

(5) Drill cuttings used by themselves or in conjunction with a drive shoe, packer or boot are not approved materials for grouting the annulus of any well.

(6) Grouting required for Community and Noncommunity Public Water Supply Wells. It is the obligation and responsibility of the driller to follow procedures set forth by the Missouri public drinking water rules.

(7) Driven Casing Wells. The bottom of the steel well casing shall be equipped with a drive shoe or otherwise protected from damage during construction of the well as dictated by drilling procedures and conditions of each particular well (see 10 CSR 23-3.100(4)(D)3. for grouting techniques).

(8) Capping. Temporary capping of a well until the pumping equipment is installed shall allow no pollution or foreign objects to enter the well.

(9) Alignment. A well shall not vary from the vertical or alignment so as to interfere with installation and operation of the pump.

(10) Well Development. The well shall be developed to remove any material deposited on the aquifer face during the drilling, drilling fluid and the predetermined finer fraction of a gravel pack, all of which shall bedone to ensure that the maximum practical specific capacity will be obtained from the completed well.

(11) For further construction requirements for domestic wells see 10 CSR 23-3.090 Regionalization and 10 CSR 23-3.100 Sensitive Areas.

(12) Multifamily wells are water supply wells constructed for the purpose of serving more than three (3) dwellings but having less than fifteen (15) service connections and regularly serves less than twenty-five (25) individuals daily at least sixty (60) days out of the year. A multifamily well must be constructed as follows:

(A) Minimum casing lengths for multifamily wells are the same as domestic wells. Liner may not substitute for casing;

(B) The drill hole shall be constructed a minimum of ten inches (10") in diameter. An increase in hole size to ten and five-eighths inches (10 5/8") in diameter will be effective May 1, 1999. The drill hole must be at leastfour inches (4") in diameter larger than the outside diameter of the steel casing to be installed;

(C) The casing used must be of ferrous material and conform to size, wall thickness and weight/foot parameters set out in subsection (1)(E), for multifamily wells. Plastic casing may be used if approved in advance on a case-by-case basis;

(D) The casing must be grouted full-length with grout utilizing the tremie method or one (1) of the pressure grouting methods set out in section (3) of this rule;

(E) The neat cement grout must be allowed to set up based on the parameter of the following:

1. Hi-early cement-minimum of twelve (12) hours;
2. Portland Type I cement-minimum of seventy-two (72) hours; and
3. High solids bentonite slurry-varies based on additives and manufacturer's specifications; and

(F) When drilling starts, after cement has set, care should be taken when drilling out the bottom of the casing so that curing cement is not damaged.

(13) Unconsolidated Material Irrigation Well. A well drilled into alluvial, glacial drift or glacial outwash aquifers that is not deeper than two hundred feet (200') and produces water not for human consumption shall conform to the following construction requirements:

(A) The selection of casing shall take into consideration the stress to which the pipe will be subjected during construction and the corrosiveness of the groundwater. Used pipe is prohibited. If steel casing is selected, see subsection (1)(E) Steel Casing Table, for size, wall thickness and weight per foot specifications. If plastic casing is selected (see 10 CSR 23-3.070 for specifications);

(B) Unconsolidated material irrigation wells greater than two hundred feet (200') in depth must be constructed using bedrock irrigation specifications contained in section (14);

(C) The drill hole shall be constructed a minimum of four inches (4") in diameter larger than the outside diameter of the casing to be installed;

(D) Set Screen and Casing. Screen openings shall provide the maximum amount of open area consistent with strength of screen and the grading of the water-bearing formation and gravel pack. The openings shall permit maximum transmitting ability without clogging or jamming;

(E) Gravel Pack. All gravel placed into well shall be clean, washed and disinfected prior to placement or provisions made for disinfection in place. When an oversized drill hole is constructed to permit the placement of a gravel wall around the well screen and casing, grouting and sealing may be suspended for sixty (60) days to allow for gravel to settle and for well development; and

(F) Grouting. After the well has been developed and pumped, but in no case later than sixty (60) days, dig around the well to a depth of four feet to five feet (4'-5') and fill with sodium bentonite granules, pellets, tablets or chips. Bentonite slurry or organic polymers shall not be used.

(14) Bedrock Irrigation Well. These wells are drilled into bedrock aquifers that are constructed to meet required standards and are equipped with a pump that has the capacity to produce more than seventy (70) gallons of water per minute. The produced water is for irrigating crops but may be used for human consumption. This type of well shall conform to the following construction requirements:

(A) The minimum amount of casing set must be determined by the division in advance on a casing point request form. A casing point request form is available from the division;

(B) The drill hole shall be constructed a minimum of ten inches (10") in diameter. The drill hole must be at least four inches (4") in diameter larger than the outside diameter of the steel casing to be installed;

(C) The casing used must be of ferrous material and conform to size, wall thickness and weight/foot parameters set out in subsection (1)(E), for high yield and bedrock irrigation wells; and

(D) The casing must be grouted full-length with neat cement grout utilizing the tremie method or one (1) of the pressure grouting methods set out in section (3).

(15) High Yield Well. Those wells that are constructed to meet required standards and are equipped with a pump that has the capacity to produce more than seventy (70) gallons of water per minute.

(A) The minimum amount of casing set must be determined by the division in advance on a casing point request form. A casing point request form is available from the division.

(B) The drill hole a minimum of ten inches (10") in diameter shall be constructed. The drill hole must be at least four inches (4") in diameter larger than the outside diameter of the steel casing to be installed.

(C) The casing must be of ferrous material and conform to size, wall thickness and weight/foot parameters set out in subsection (1)(E), for high yield and bedrock irrigation wells.

(D) The casing must be grouted full-length with neat cement grout utilizing the tremie method or one (1) of the pressure grouting methods set out in section (3).

(16) Lubricants Used During the Drilling Process. During the drilling of a well, some lubricants may be necessary to ensure protection of the drilling machine. The lubricants used must not adversely affect the groundwater quality and must be biodegradable. Special care must be taken to ensure leaking hoses on the drilling machine do not allow harmful lubricants or fluids to enter the borehole.

(17) Most domestic bedrock wells drilled in the state have an eight and five-eighths-inch (8 5/8") hole drilled to casing point and a six and five-eighths-inch (6 5/8") outside diameter casing installed into bedrock. The rules state that the bottom thirty feet (30') of the annulus must be grouted. Table 1 states the minimum amount of grout required to fill the bottom thirty feet (30') of annulus taking into account the use of a six and five-eighths-inch (6 5/8") outside diameter casing, borehole size differences, type of grout utilized, and method of emplacement of the grout.

Click to view TABLE 1: Number of Bags for Minimum Amount of Required Grout for a Domestic Bedrock Water Well

Click to view TABLE 2: Number of Bags for Minimum Amount of Required Grout for Domestic Unconsolidated Water Wells

(18) Most alluvial domestic wells drilled in the state have a ten and five-eighths-inch (10 5/8") hole drilled and a six and five-eighths inch (6 5/8") outside diameter casing installed. The rules state that the top twenty feet (20') of annulus must be grouted. The following amounts of grout are necessary, at a minimum, to fill this space: Table 2 states the minimum amount of grout required to fill the top twenty feet (20') of annulus taking into account the use of a six and five-eighths- inch (6 5/8") outside diameter casing and screen, borehole size differences, type of grout utilized, and method of emplacement of the grout.

(19) When drilling in Area 2 or 3, under certain circumstances, domestic wells may be constructed where the upper forty feet (40') of annulus is grouted. This annulus is created by a ten and five-eighths-inch (10 5/8") hole and a five and one-half-inch (5 1/2") outside diameter casing. The following amounts of grout are necessary, at a minimum, to fill this space:

(20) Domestic wells drilled in Area 5 can have casing as small as four and one-half-inch (4 1/2") outside diameter placed in a hole that is eight and five-eighths-inch (8 5/8") in diameter. To grout the upper twenty feet (20') of this type of well the following amounts of grout are necessary, at a minimum, to fill this space:

AUTHORITY: sections 256.606, 256.614, 256.615 and 256.626, RSMo 1994.* Original rule filed April 2, 1987, effective July 27, 1987. Emergency amendment filed Nov. 16, 1993, effective Dec. 11, 1993, expired April 9, 1994. Amended: Filed Aug. 17, 1993, effective March 10, 1994. Amended: Filed July 13, 1994, effective Jan. 29, 1995. Amended: Filed Nov. 1, 1995, effective June 30, 1996.
*Original authority: 256.606, RSMo 1991; 256.614, RSMo 1985, amended 1991; 256.615, RSMo 1991; and 256.626, RSMo 1985, amended 1991.

MO Dept. of Natural Resources: CODE OF STATE REGULATIONS - Matt Blunt (11/30/01) Secretary of State

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