Current through Register Vol. XLI, No. 36, September 6, 2024
Section 64-46-6 - Construction; general6.1. The minimum protected depths of drilled wells shall provide watertight construction to the depth required by the Commissioner to: exclude contamination; seal off formations that are, or may be, contaminated or yield undesirable water; and provide a minimum casing length as follows: 6.1.a. Nineteen (19) feet of casing in unconsolidated water bearing formations below ground level plus at least one (1) foot above finished grade, resulting in a total of twenty (20) feet;6.1.b. Nineteen (19) feet of casing in bedrock wells with a minimum of five (5) feet of casing installed into unweathered bedrock below ground level, plus at least one (1) foot above finished grade resulting in a total of twenty (20) feet; or6.1.c. The Commissioner may require other minimum casing depths in special circumstances.6.2. The minimum borehole diameter, at the top of the water well, shall be four (4) inches.6.3. The full length of the well casing shall be fully grouted from the lower terminus up to the ground surface, except as noted in subdivisions 6.3.a through 6.3.c of this section. 6.3.a. When drilling through caves, mines, or other cavities, the lower portion of the casing shall be grouted in accordance with the method described in subdivision 6.4.d of this section and a packer or similar bridging device shall be used to permit grouting above the cavity.6.3.b. In unconsolidated aquifers (i.e., sand and gravel) above bedrock, the permanent casing shall be grouted.6.3.c. In cases where a pitless adaptor is to be installed, upward grouting may terminate at the pitless adaptor level to allow for the installation of a pitless adapter.6.4. All water wells shall have an annular space seal between the casing and borehole that forms a seal to prevent the entrance of water from sources other than the aquifers selected. The borehole diameter shall be sufficient to allow placement of the material to fully enclose and entirely seal the pipe. 6.4.a. When grouting below the water level, grout material shall be installed by a positive placement method, such as pumping or forced injection by air or hydraulic pressure, placed from the bottom up. The annular space shall be a minimum of 1.5 inches completely around the casing for grout. Grout shall be injected in the annular space between the inner casing and either the outer casing or the borehole. In wells where the outer casing shall be left in place, a dry bentonite is used while driving the casing.6.4.b. When grouting above the water level, grout material installed by a positive placement method, such as pumping or forced injection by air or hydraulic pressure, placed from the bottom up, is the preferred method for grouting. The annular space shall be a minimum of 1.5 inches completely around the casing. A gravity emplacement method may be used for grouting above the water level, not exceeding thirty (30) feet in depth.6.4.c. When under-reaming is used to set permanent casing in unconsolidated materials, either a dry or wet bentonite grout shall be used at the ground surface while the casing is being installed. Upon termination of casing in unweathered bedrock and removal of the under-reamer, bentonite or neat cement shall be placed in the bottom of the casing by a positive displacement or gravity placement method before casing is set in bedrock.6.4.d. If rapid loss of grout material occurs during emplacement, coarse fill material (e.g., sand, gravel, crushed stone or dry cement) may be used in the zones in which the loss is occurring. The remainder of the annular space shall be grouted as provided in this section.6.4.e. When driving casing with a cable tool rig through unconsolidated alluvial formations, a cone shaped depression or temporary outer casing filled with bentonite grout shall be maintained around the outside of the casing. The bottom of the driven casing shall be equipped with a drive shoe.6.4.f. If the annular space cannot be grouted in accordance with this section, alternative methods shall obtain the written approval of the Commissioner.6.4.g. The annular space shall be grouted as soon as possible, but not later than seven (7) calendar days after the well drilling has been completed and the drill rig is removed from the drill site location of a well.6.5. Every well shall be developed to remove the native silts and clays, drilling mud, or finer fraction of the gravel pack resulting from drilling operations.6.6. During the progress of work, water wells shall be provided protection to prevent tampering with the well or entrance of foreign materials. Once well drilling is complete and prior to departure of the drilling equipment from the well site, a WSC approved vector proof cap shall be securely installed. The well cap shall provide for ventilation. Vents shall be part of the well cap or may be attached to the well cap. They shall be turned down and screened to prevent entry of vermin. Toxic or flammable gasses shall be vented from a well to the outside above roof level or a point where they shall not produce a hazard. Wells installed in flood prone areas shall be watertight to prevent intrusion of floodwaters.6.7. Permanent casing for all groundwater sources shall project a minimum of twelve (12) inches above the ground surface upon completion.6.8. Pitless units designed to replace a section of well casing shall meet the standards of the WSC and shall be factory fabricated from point of connection with the well casing to the unit cap or cover. The materials used shall be durable and approved by the WSC. The pitless unit shall: 6.8.a. form an unbroken extension of the well casing from the point of discharge to a point above ground level as specified for upper well terminals; and6.8.b. be installed by a threaded connection or welded to the cutoff casing. A compression flange gasket is not allowed. The threaded or welded connection to the cutoff casing shall be watertight.6.9. Commercially manufactured pitless adapters shall be connected to the well casing with clamps, compression nuts, or by welding and shall form a watertight seal. To assure a watertight seal between the pitless adapter and the well casing, care shall be used in cutting the hole in the well casing with a hole-cutting saw or other Commissioner approved methods. All burs from the cutting process shall be removed. Both the outside and the inside surfaces of well casing surrounding the hole shall be smoothed. Pitless adapters shall be installed according to manufacturer's specifications and shall meet the standards of WSC. 6.9.a. Pitless adapters shall be constructed and installed to prevent the entrance of contaminants into the well or water supply through openings in the well casing.6.9.b. The pitless adapter shall provide adequate clearance within the well to allow insertion and withdrawal of the pump and system components through the upper terminal of the well casing.6.10. Pump installation contractors shall not cut off or penetrate well casing below ground level except to install a pitless adapter or a pitless unit. A certified pump installer may join casing in accordance with this rule after obtaining the proper permit.6.11. Well houses, if constructed, shall not be built directly over a water well.