Conn. Agencies Regs. § 25-128-57 - Procedure of abandonment

In the event of abandonment of any water supply well or other type of well the proper procedure and materials shall be used as follows:

(a) The well shall be plugged to prevent the entrance of surface water, circulation of water between or among producing zones, or any other process resulting in the contamination or pollution of Groundwater resources.
(b) In the event of temporary abandonment or discontinuance of the use of any well, the well shall be sealed with a watertight cap or seal, as provided in subsection (e) of this section.
(c) The well shall be chlorinated prior to abandonment using a chlorine solution with a minimum concentration of one hundred fifty parts per million (150 ppm) of chlorine.
(d) The well shall be checked from land surface to the entire depth of the well before it is sealed, to insure against the presence of any obstruction that will interfere with sealing operations.
(e) The well bore shall be filled and sealed with any of the following materials: neat cement grout, sand cement grout, bentonite clay grout, or sand clay or bentonite cement grout. Dug wells may be abandoned with clean sand and gravel.
(f) The grout material shall be placed in such a way to prevent voids in the grout or dilution of the grout.
(g) Any well constructed in a consolidated rock formation, may be filled with fine sand in the zone or zones of consolidated rock. The top of the sand fill shall be at least ten (10) feet below the bottom of the casing, and the remaining portions of the well shall be filled with neat cement grout, sand cement grout, bentonite clay grout, or sand clay or bentonite cement grout.
(h) Any test well or bore shall be abandoned in such a manner that it does not become a channel for the vertical movement of water or other substance to the potable Groundwater resources.
(i) Deep waste disposal or oil wells with casings free of any breaks, and extending below the potable Groundwater zones, may be sealed with a watertight cap or welded plate.
(j) Upon completion of abandonment of the well, the top of the casing or grout material may be terminated at least four (4) feet below the ground surface.


Conn. Agencies Regs. § 25-128-57
Effective May 21, 1993; amended 7/8/2022

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