10 CSR 23-3.040 Well Casing Seals and Connections PURPOSE: This rule describes the types of well casing seals and connections that are to be used.

(1) Above-Grade Connections. An abovegrade connection into the top or side of a well casing shall be at least one foot (1') above the finished grade surface and constructed to exclude dirt or other foreign matter by one (1) or more of the following methods, as may be applicable:

(A) Threaded connection;
(B) Welded connection;
(C) Rubber expansion sealer;
(D) Bolted flanges with rubber gaskets;
(E) Overlapping well cap; and
(F) Extension of the casing at least one inch (1") into the base of a power pump.

(2) In wells that utilize an above grade connection, special attention must be paid to the sealing capabilities of the selected well casing seal. In many cases the electric wire hole, the drop pipe hole and the vent pipe hole may not be sealed adequately. The casing seal must stop all bacteria from entering the well through the seal. It is recommended that these holes be caulked, with silicone caulk or equivalent, to ensure that bacteria or other contaminants are not pulled into the well when the pump is operating.

(3) The practice of cutting the rubber well seal to make removal and reinstallation easier is strictly prohibited.

(4) Below-Grade Connection. A connection to a well casing made below ground, or less than one foot (1') above the finished surface grade, shall be protected by a pitless adapter or pitless unit. The pitless adapter or pitless unit shall be composed of material of sufficient strength to withstand normal operating stress. A below-ground connection shall not be submerged in water at the time of installation. Holes cut in the casing through which the pitless adaptors are installed must be sized and constructed so as to guarantee a watertight seal with the pitless adaptor in place. Native materials shall be packed tightly around the casing and pitless adapter or pitless unit after installation.

(5) Well Caps for Wells Using Pitless Adapters. Well caps used on wells that have a pitless adapter or pitless unit must have a screened vent hole pointing downward at least one-half inch (1/2") in diameter and must seal tightly against the casing to exclude dirt, insects or any foreign matter from entering the well. Hub cap type well caps that are secured to the casing by set screws that leave an opening allowing contaminants to enter are not approved for use.

(6) Other methods. Any other method of connection to a well casing shall be specifically approved by the division before installation.

(7) Wells drilled in floodplains must have casing that terminates at least two feet (2') above the maximum known floodwater elevation or when flooding is eminent, the well vent must be sealed and the well discontinued from operation until the floodwater subsides.

AUTHORITY: sections 256.606 and 256.626, RSMo Supp. 1991.* 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.
*Original authority: 256.606, 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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