(A) For all wells plugged with prepared clay, a clay slurry shall be placed in the following intervals in the well bore:
(1) From total depth to a minimum of five hundred feet above the top of the lowest reservoir rock penetrated or perforated.
(2) From a minimum of fifty feet below the base of each succeeding reservoir rock formation to a minimum of two hundred feet above the top of such formation, until the plugging operation has been completed to within a minimum of one hundred feet of the bottom of the surface casing.
(3) From approximately fifty feet below the base of the fresh water strata to a minimum of thirty inches below the grade level.
(4) A bridge shall be placed in the well bore a minimum of two hundred feet below the coal seam, and the well bore shall be filled with an approved material from the top of such bridge to within a minimum of thirty inches below the grade level.
(B) During the plugging operation a good faith effort must be made to recover all, casing which is not cemented, excluding conductor pipe. When a string of casing has been withdrawn by either removing the casing above the casing seat, or by parting the casing string, an approved precast concrete plug may be lowered in place either on the casing seat or on the parted casing point to serve as a base for a prepared clay plug. If the surface casing is parted during the pulling operation, and cannot be recovered or removed, the well will be filled from the previous set plug to thirty inches below grade level with prepared clay.
(C) The chief or his authorized representative may also require or approve the placing of brush and stone bridges, and/or mechanical bridges in the well bore or casings, when in his judgment such bridges will be necessary to ensure that the prepared clay placed in the well remains at the point in the well where such prepared clay had been placed.
(D) A precast concrete plug shall be placed on the top of the conductor pipe or surface casing.
(E) In the event that it is determined by the inspector that borehole conditions render compliance with the above plugging procedures impossible or impractical or if it is determined by the inspector that the above procedures will not fulfill the requirements as set forth under paragraph (A) of rule 1501:9-11-03 of the Administrative Code, then the inspector may designate an alternate thickness and method of emplacement of the plugs to ensure compliance with paragraph (A) of rule 1501:9-11-03 of the Administrative Code.
(F) In order to promote enhanced recovery, including but not limited to secondary and tertiary operations, the chief or his authorized representative may require special plugging conditions.
Cite as Ohio Admin. Code 1501:9-11-09