PURPOSE: This rule provides for the protection of both surface water and groundwater. Drilling muds, oil, and water recovered from drilling or testing operations should be disposed of so that pollution of surface soil, ponds, and streams is avoided. Underground sources of drinking water strata are protected by casing set below the deepest strata penetrated that might contain underground sources of drinking water. Dry holes should be plugged in a manner that subsurface salt water or mineralized water will be confined to the stratum in which it occurs. Similarly, each oil or gas stratum penetrated by a well should be permanently sealed when abandoned to prevent contamination of underground sources of drinking water and also to prevent damage by water of any oil or gas stratum capable of producing in paying quantities. In certain logging procedures, a radioactive source (in a probe or sonde) is lowered into the borehole to provide certain subsurface data useful in exploration for oil and gas. Should this radioactive source contained in a logging tool be lost in the hole, certain procedures are prescribed to prevent the accidental or intentional mechanical disintegration of the radioactive source. Further, there are provisions for marking the well site permanently as a warning that a radioactive source has been abandoned in the well.

1. (1) Shut-in wells.

   1. (A) Shut-in status. A well is considered shut in whenever it has not been operated for ninety (90) calendar days or more. The shutin status shall not exceed ninety (90) calendar days. Prior to the expiration of the ninety (90) calendar days shut-in status, the operator of that well shall perform one (1) of the following:

      1. 1. Return the well to operation and noti-

fy the state geologist on the monthly well status report per 10 CSR 50-2.080(2); or

1. 2. Plug the well; or
2. 3. Petition the state geologist for an

extension and propose an end date for the shut-in status.

1. (B) Approval of shut-in status extensions.

   1. 1. The state geologist may approve an

extension of a well’s shut-in status not to exceed one (1) year. If the operation of any shut-in well is not resumed within one (1) year after the extension has been approved, the well will be deemed abandoned, and the operator shall plug the well per these rules. Upon application to the state geologist before the expiration of the one- (1-) year period, and for good cause shown, the period may be extended by the state geologist for one (1) year upon compliance with the provisions of paragraph (1)(B)2. of this section. Additional one- (1-) year extensions may be granted by the state geologist. The total time of such consecutive extensions shall not exceed ten (10) years.

1. 2. Any well in continuous shut-in status

must demonstrate mechanical integrity at least once every five (5) years pursuant to procedures in 10 CSR 50-2.055.

1. (C) Right of denial. Any shut-in well may be inspected by the state geologist to determine whether its shut-in status could cause contamination of underground sources of drinking water. If necessary, the state geologist may deny extensions of shut-in status for a well and require the well be plugged, repaired, or demonstrate mechanical integrity in accordance with these regulations.
2. (D) Plugging of shut-in wells. If the well is not returned to service or properly plugged pursuant to these rules before the end of the shut-in status, the well will be considered abandoned and shall be plugged within thirty

1. (30) calendar days. After the thirty- (30-) day period, if the well has not been plugged pursuant to these rules, the bond in place for the well shall be forfeited and deposited into the Oil and Gas Remedial Fund according to 10 CSR 50-2.020(6) and utilized according to 10 CSR 50-2.060(3)(F).
2. (2) Shut-off test. Whenever it appears to the state geologist that any water from any well is migrating or infiltrating into oil-bearing or gas-bearing strata or that any detrimental substances are infiltrating any underground sources of drinking water, the state geologist may require a shut-off test, to be conducted at the expense of the operator of that well. The time and procedure for the taking of the test will be fixed by the state geologist. Reasonable notice of the test will be given to the owner or operator. The owner or operator of any abandoned oil or gas well from which water is migrating or infiltrating into any oilbearing or gas-bearing strata, or from which any detrimental substances are infiltrating any underground sources of drinking water, shall immediately plug or repair the well in accordance with section (3) below and shall prevent the infiltration of oil, gas, produced water, or other detrimental substances into underground sources of drinking water strata.

3. (3) Plugging Requirements.

   1. (A) Abandoned Wells.

      1. 1. An abandoned well shall be plugged

or addressed as directed by the state geologist as provided in these rules. Plugging an abandoned well includes the removal of any rig, derrick, or other operating structure, and all 10 CSR 50-2

abutments and appurtenances used in the operation of such well, from the land upon which the well was operated, and includes grading the surface of the soil in such manner as to leave the land, as nearly as practicable, in the same condition after the removal of such structures, equipment, and appurtenances as it was before such structures and abutments were placed thereon, unless the owner of the land and the plugging party have entered into an agreement providing otherwise.

1. 2. When the state geologist investigates

and determines that a well has been abandoned, as provided in these rules, the state geologist may issue an order directing the operator, owner, or any person who without authorization tampers with or removes surface equipment or downhole equipment from the abandoned well to plug the well as directed by the state geologist. If the person to whom the order is issued fails to comply with any such order that has become final under 10 CSR 50-1.040, the person to whom the order is issued shall be deemed to have abandoned any and all property interests in the well and any rig, derrick, or other operating structure, and all abutments and appurtenances.

1. 3. In addition to any other remedy pro-

vided in Chapter 259, RSMo, or implementing regulations, if the state geologist determines that a well has been abandoned, the department or the council may request that the attorney general institute a civil proceeding to request appropriate injunctive relief, civil penalties, or other appropriate remedy, as provided in sections 259.200 and 259.210, RSMo.

1. 4. If the state geologist determines that

a well has been abandoned, the department in accordance with section 259.070.5(7), RSMo, may plug such well, or cause it to be plugged as to prevent contamination or danger of contamination of any waters of the state or loss of underground sources of drinking water, and may remediate contamination from the well. Plugging or remediation may include the collection, removal, salvage, and disposition of abandoned operating structures or other equipment. The cost of the plugging or remediation will be paid by the Oil and Gas Remedial Fund, as provided in section 259.190, RSMo.

1. (B) Notice.

   1. 1. Before plugging any well the operator

shall file with the state geologist a notice of intent to plug on a form provided by the department. The notice will include the details of the proposed plugging procedure and description of any logging tool containing a radioactive source being abandoned (see subsection (E) of this section for radioactive source abandonment procedure). The proposed plugging procedure shall be approved by the state geologist prior to commencement of plugging activities.

1. 2. The operator shall notify the state

geologist no later than five (5) business days before the plugging.

1. 3. Exceptions.

   1. A. If necessary to avoid rig down-

time, oral permission to plug dry holes may be obtained by informing the state geologist of proposed plugging procedures, in which case a notice of intent to plug form must be submitted within three (3) business days of plugging.

1. B. In lieu of prior notice and approval

by the state geologist as detailed in paragraph (3)(B)1. of this rule, the operator may elect to plug a well from total depth to the surface with cement slurry, being no less than fifteen (15) pounds per gallon density, emplaced via a tremie pipe.

1. C. If an emergency situation exists,

the operator shall orally notify and present the plugging proposal to the state geologist for approval.

1. (C) Plugging methods.

   1. 1. Before any well is considered

plugged, all oil, gas, and water shall be permanently confined in the separate strata originally containing them.

1. 2. Plug wells by emplacing cement via a

tremie pipe from twenty-five feet (25') below the bottom of the stratum to a point no less than twenty-five feet (25') above the top of the stratum that contains oil or gas, or from which oil or gas has been produced, or that has been used for injection.

1. 3. Cut off casing in plugged wells,

including horizontal wells, at least three feet (3') below ground surface at the wellhead.

1. 4. Horizontal wells. Fill each horizontal

well with a cement plug from total depth of the deepest producing horizon to the surface.

1. 5. Stratigraphic test wells. Fill each

stratigraphic test well with a cement plug from total depth to within three feet (3') of the surface. All stratigraphic test wells shall be plugged after being used as soon as is reasonably practicable but no later than thirty (30) calendar days after the drilling of the well.

1. 6. Seismic shot holes. Plug all seismic

shot holes upon completion of the shooting. Such holes shall not remain unplugged for a period of more than thirty (30) calendar days after the drilling of the hole.

1. 7. If circulation is lost in the drilling of

any hole and circulation cannot be regained, place a cement plug above the zone of lost circulation to the surface.

1. 8. Alternative plugging methods may be

authorized by the state geologist when geologic conditions or conditions in the casing or wellbore warrant.

1. (D) Reporting. The operator shall submit a plugging record completed in full on a form provided by the department along with the applicable fee pursuant to 10 CSR 50-1.050 to the state geologist within thirty (30) calendar days after completion of plugging activities.

2. (E) Radioactive source.

   1. 1. If a radioactive source cannot be

retrieved from a hole and is proposed to be abandoned in the well, the operator shall notify the state geologist. Wells in which radioactive sources are being abandoned shall be mechanically equipped so as to prevent the accidental or intentional mechanical disintegration of the radioactive source.

1. A. Sources being abandoned in a well

shall be covered with no less than a fifty foot (50') standard-red-dyed cement plug with a whipstock set on top of the plug. The dye is to alert the re-entry operator prior to encountering the source.

1. B. In wells where a radioactive log-

ging source has been cemented in place behind a casing string and above total depth, upon abandonment a standard-red-dyed cement plug should be placed opposite the abandoned source and extend fifty feet (50') above and fifty feet (50') below with a whipstock placed on top of the plug.

1. C. If the operator finds after expend-

ing a reasonable effort it is not possible to abandon the source as prescribed in subparagraph (3)(E)1.A. or B. of this rule, the operator shall seek the state geologist’s approval to cease efforts in this direction and obtain approval for an alternate abandonment procedure.

1. 2. Upon permanent plugging of any well

in which a radioactive source is abandoned, and after removal of the wellhead, a permanent plaque is to be attached to the top of the casing left in the hole in a manner that reentry cannot be accomplished without disturbing the plaque. This plaque would serve as a visual warning to any person re-entering the hole that a radioactive source has been abandoned in place in the well. The plaque should contain the trefoil radiation symbol with a radioactive warning and should be constructed of a long-lasting material such as monel, stainless steel, or brass.

1. (F) Monies deposited in the Oil and Gas Remedial Fund may be used by the department to plug those oil, gas, and injection wells that have been abandoned and have not been plugged according to these rules, subject to the following guidelines:

   1. 1. Wells covered by a forfeited bond will

receive first priority; and

1. 2. Other wells will receive secondary

priority on the basis of their potential for groundwater contamination or other damage in the order recommended by the state geologist.

1. (4) Conversion to domestic water supply well. Within thirty (30) calendar days after conversion of a well to a domestic water supply well, submit an application on a form provided by the department. The well must have been reconstructed, or, for a stratigraphic test well, have been constructed, as a water well by a Missouri permitted water well installation contractor and meet minimum water well construction standards as set forth in the Water Well Drillers’ Act, Chapter 256, RSMo, and the implementing Missouri Well Construction rules 10 CSR 23. A well registration or certification, as appropriate, per those rules shall be approved before the state geologist will approve the conversion agreement and release the applicable bond.

AUTHORITY: sections 259.070 and 259.190, RSMo 2016.* Original rule filed Oct. 11, 1966, effective Oct. 21, 1966. Amended: Filed Sept. 12, 1973, effective Sept. 22, 1973. Amended: Filed Dec. 12, 1975, effective Dec. 22, 1975. Amended: Filed Sept. 10, 1979, effective Feb. 11, 1980. Amended: Filed Oct. 14, 1981, effective Feb. 1, 1982. Amended: Filed Sept. 13, 1983, effective Dec. 11, 1983. Amended: Filed Sept. 15, 2015, effective March 30, 2016. Amended: Filed June 27, 2018, effective Feb. 28, 2019. *Original authority: 259.070, RSMo 1965, amended 1972, 1983, 1987, 1993, 1995, 2012, 2015 and 259.190, RSMo 1965, amended 1983, 2015.