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Unless altered, modified, or changed by the board for particular common sources of supply, the following rules apply to drilling wells with rotary tools.

(1) Suitable and safe surface casing must be used in all wells. Sufficient surface casing must be run to reach a depth below all fresh water located at levels reasonably accessible for agricultural and domestic use. Surface casing must be set in or through an impervious formation and must be cemented by the pump-and-plug or displacement method with sufficient cement to circulate to the top of the well. If it becomes necessary to run a production string, such string must be cemented by the pump-and-plug method or any other method approved by the board administrator and must be properly tested by the pressure method before cement plugs are drilled.

(2) All cemented casing strings shall stand under pressure until the cement has reached a compressive strength of 300 pounds per square inch; provided, however, that no tests shall be commenced until the cement has been in place for at least 8 hours. The requirement "under pressure" as used herein will be complied with if one float valve is used or if pressure is otherwise held.

(3) Blowout prevention equipment must be installed and maintained on all wells in accordance with the requirements of ARM 36.22.1014.

(4) Freshwater-based drilling fluid or air must be used when drilling the surface hole prior to setting surface casing and when drilling through freshwater aquifers anywhere within the state of Montana.

History: Sec. 82-11-111, MCA; IMP, 82-11-123 and Sec. 82-11-124, MCA; Eff. 12/31/72; AMD, Eff. 7/5/75; AMD, 1982 MAR p. 1205, Eff. 6/18/82; AMD, 1982 MAR p. 1398, Eff. 7/16/82; AMD, 1992 MAR p. 654, Eff. 4/1/92.

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