26.04.04.36

.36 Well Sealing Procedures.

A. Preliminary Work Before Sealing a Well.

(1) The well shall be investigated to determine:

(a) Its present condition;

(b) The details of its construction; and

(c) Whether there are any obstructions that will interfere with the process of filling and sealing.

(2) If there are any obstructions, they shall be removed, if possible, by cleaning the hole or redrilling.

(3) Liners shall be removed prior to sealing or an alternate sealing plan must be approved by the Approving Authority.

B. Filling and Sealing Wells.

(1) In all hydrogeologic areas of the State, the annular space of cased wells shall be sealed.

(2) Wells in an unconfined aquifer in Hydrogeologic Areas 1 and 2 shall be sealed by either of the following procedures:

(a) If the well casing is not removed, fill the well with sealing material; or

(b) If the well casing is removed, fill the entire length of the borehole with sealing material.

(3) Wells in a confined aquifer in Hydrogeologic Area 2 shall be filled and sealed by either of the following procedures:

(a) If the casing has been removed, the well shall be filled the entire depth with sealing material; or

(b) If the casing has not been removed:

(i) Consideration shall be given to perforating or ripping the casing opposite the confining layers; and

(ii) The well shall be filled with sealing material.

(4) Unconfined wells less than 2-inch diameter shall be sealed only with neat Portland cement.

(5) Wells in Hydrogeologic Areas 3, 4, and 5 Filling and Sealing Procedures.

(a) Fill material shall extend from the bottom of the well to within 20 feet of the casing bottom, except for filling materials used in unsuccessful wells under Regulation .35C(2) of this chapter.

(b) If rapid loss of sealing material into the rock occurs during emplacement, coarse fill material may be used to fill voids.

C. Placement of Material. The following standards shall be met in placing filling or sealing materials:

(1) The well shall be sealed with the appropriate material emplaced from the top of the fill material;

(2) When neat Portland cement, concrete, or bentonite slurry is used, it shall be placed in one continuous operation utilizing a pipe extended to the bottom of the interval to be sealed except as noted in §D of this regulation;

(3) Bentonite chips or pellets:

(a) Shall be used in such a way as to prevent bridging, but if bridging occurs, the well shall be drilled out;

(b) May not be used for casing diameters smaller than 2 inches; and

(c) Shall follow the specific product manufacturer’s instructions for their use.

D. Special Procedures for Filling and Sealing Certain Wells.

(1) A dug well shall be filled and sealed by the following procedure:

(a) Placing fill material in the well to a level approximately 5 feet below the land surface;

(b) Placing a 2-feet thick layer of concrete above the fill; and

(c) Filling the remainder of the well to the ground surface.

(2) A monitoring well shall be sealed by the following procedure:

(a) For monitoring wells less than 50 feet in depth:

(i) Ripping or removing the casing; and

(ii) Filling the well with sealing material; or

(b) For monitoring wells greater than 50 feet in depth follow the procedures specified in §B of this regulation.

(3) A geothermal well shall be sealed by;

(a) Removing all fluids from the tubing; and

(b) Filling the tubing and any open portion of the borehole with grout.