R647-2-108. Hole Plugging Requirements

Drill holes shall be properly plugged as soon as practical and not be left unplugged for more than 30 days without approval of the Division. The procedures outlined below are required for the surface and subsurface plugging of drill holes. The Division may approve an alternate plan, if the operator can prove to the satisfaction of the Division that another method will provide adequate protection to the groundwater resources and long term stability of the land. Dry holes and nonartesian holes which do not produce significant amounts of water may be temporarily plugged with a surface cap to permit the operator to re-enter the hole for the duration of operations.

1. Surface plugging of drill holes shall be accomplished by:

1.11. Setting a nonmetallic permaplug at a minimum of five (5) feet below the surface, or returning the cuttings to the hole and tamping the returned cuttings to within five (5) feet of ground level. The hole above the permaplug or tamped cuttings will be filled with a cement plug. If cemented casing is to be left in place, a concrete surface plug is not required provided that a permanent cap is secured on top of the casing.

1.12. If the area is tilled farmland, a five (5) foot cement plug must be placed above a permaplug or tamped cuttings so that the top of the cement plug is a minimum of three (3) feet below the ground surface. The hole above the cement plug is to be filled with soil. If cemented casing is to be left in place, a concrete surface plug is not required provided that a permanent cap is secured on top of the casing. The top of the casing and cap must be a minimum of three (3) feet below the ground surface.

2. Drill holes that encounter water, oil, gas or other potential migratory substances and are 2-1/2 inches or greater in surface diameter shall be plugged in the subsurface to prevent the migration of fluid from one strata to another. If water is encountered, plugging shall be accomplished as outlined below:

2.11. If artesian flow (i.e., water flowing to the surface from the hole) is encountered during or upon cessation of drilling, a cement plug shall be placed to prevent water from flowing between geologic formations and at the surface. The cement mix should consist of API Class A or H cement with additives as needed. It should weigh at least 13.5 lbs./gal., and be placed under the supervision of a person qualified in proper drill hole cementing of artesian flow. Artesian bore holes must be plugged in the described manner, prior to removal of the drilling equipment from the well site. If the surface owner of the land affected desires to convert an artesian drill hole to a water well, the owner must notify the Division in writing accepting responsibility for the ultimate plugging of the drill hole.

2.12. Holes that encounter significant amounts of nonartesian water shall be plugged by:

2.12.111 Placing a 50 foot cement plug immediately above and below the aquifer(s); or

2.12.112 Filling from the bottom up (through the drill stem) with a high grade bentonite/water slurry mixture. The slurry shall have a Marsh funnel viscosity of at least 50 seconds per quart prior to the adding of any cuttings.