Okla. Admin. Code § 785:35-7-1

Current through Vol. 42, No. 4, November 1, 2024

Section 785:35-7-1 - Minimum standards for construction of groundwater wells, fresh water observation wells, and water well test holes

(a)General requirements.

(1)Minimum standards. The minimum standards set forth in this subchapter apply to all groundwater wells, fresh water observation wells and water well test holes whether constructed by a person having a valid license or by any other person. More stringent construction standards may be required for areas of known contamination as identified in Chapter 45, Appendix H.

(2)Construction of wells. Flowing and non-flowing groundwater wells, observation wells and water well test holes are to be constructed in a manner as to prevent waste and to prevent contamination of groundwater by pollution material either entering the ground around the casings or tubing, or entering the fresh groundwater from pollution sources below the ground, or by entering the fresh well water by leaking wells, casing pipe fittings, pumps, or well seals.

(3)Proper maintenance, plugging and capping. The well driller and/or the well owner are charged with the responsibility of taking whatever steps are reasonable in a particular situation to guard against waste and contamination of the groundwater resources, and to see that unused wells are properly capped or plugged.

(4)Minor and small public water supply wells. Prior to drilling a well that will be used in a minor or small public water supply system, a permit from the Oklahoma Department of Environmental Quality (ODEQ) must be obtained. Minor and small public water supply systems are defined in OAC 252:624-1-2 of the ODEQ regulations.

(b)Minimum location standards.

(1) Every new groundwater well, fresh water observation well and water well test hole shall be located a minimum distance from possible pollution sources as prescribed in this subsection or as otherwise authorized by a variance granted by the Executive Director. Possible pollution sources include but are not limited to existing or proposed septic tanks, sewer lines, absorption fields or beds, seepage pits, building foundations, waste pits, lagoons, oil or gas wells, and landfills. The minimum distance between the possible pollution source and the well or test hole shall be as follows, provided that other governmental agencies may require wells to be located at distances greater than the minimum distances set forth in this paragraph:

(A) 10 feet from a closed or tight sanitary sewer line, 25 feet from aerobic (above ground) sprinkler spray, and 50 feet from an aerobic sprinkler head,

(B) 300 feet from the outside perimeter of an existing or proposed waste lagoon for a feedlot or confined animal feeding operation, and

(C) 50 feet from all other pollution sources, provided however, if the well is 50 feet to 75 feet and located down-gradient or level from a possible source of pollution, a twenty foot (20') surface seal shall be installed, and

(D) 75 feet from all other pollution sources if the well is level with the pollution source and 100 feet from all other pollution sources if the well is located down-gradient from the pollution source.

(2) If not prohibited by the owner of the well or other governmental agency requirements, groundwater wells which will not be used for drinking water may be located closer to a possible pollution source than the minimum distances specified in paragraph (1) of this subsection if all of the following conditions are met:

(A) the possible pollution source is not a wastewater lagoon, and not a subsurface septic system,

(B) before the well is drilled, the well driller advises the person wanting the well drilled that the well is subject to contamination,

(C) the owner of the proposed well notifies the Board that the owner will authorize the driller to drill the well closer to the possible pollution source than the minimum location standard,

(D) the outside water-tight casing is properly cement grouted or completed with ten (10) feet bentonite in the lower one-half (1/2) portion and ten (10) feet cement grout in the upper one-half (1/2) portion at least twenty (20) feet down from the land surface or pitless adaptor connection.

(3) If a well driller or other person proposing to drill a well encounters a structure, object or other situation and is unsure whether it may be a possible source of pollution, he shall contact Board staff and obtain approval for location of the well.

(c)Casing of groundwater and fresh water observation wells. Except for sand point wells, requirements for casing of groundwater wells and fresh water observation wells shall be as follows:

(1) The casing shall be installed to seal off any groundwater zones containing water which does not meet the groundwater quality standards as set forth in Oklahoma's Water Quality Standards. In no case shall a well be completed in a salt or marginal water zone.

(2) New groundwater and fresh water observation wells shall have:

(A) Outside water-tight production casing cement grouted from land surface to a minimum depth of ten (10) feet below the land surface, and to such further depth as may be necessary, depending upon the character of the underground formations, to extend into an impervious stratum, where such stratum is found above the source aquifer.

(B) Casing seated at top of the first impervious stratum suitable for casing point. Where an impervious formation or tight confined bed does not occur at the well site, the casing shall be extended as far as practicable below the water table and wherever possible, at least ten (10) feet below the minimum seasonal stage of the water table.

(C) Casing joints threaded, welded, or glued with water well construction glue so as to be water-tight.

(D) Casing that extends at least twelve (12) inches above the natural ground level or at least eight (8) inches above the floor surface (for a total of 12 inches above natural ground level) for surface pad completions. In areas where known flooding occurs, the casing shall extend twenty-four (24) inches above the maximum level of such flooding.

(E) Casing meeting or exceeding the following:

(i) new or clean and sanitary used carbon or stainless steel, or

(ii) new PVC fresh water well casing which has a S.D.R. rating of twenty-six or stronger and which may be plain end with threaded connector, and with all joints made water-tight by cleaning and cementing, using manufacturer's recommended thinner and cement for use in fresh water wells, or

(iii) fiberglass or other material which meets or exceeds N.S.F. approval for casing which is specially designed for use in a water well.

(d)Cement grouting and concreting. Except for sand point wells, cement grouting and concreting requirements for groundwater wells and fresh water observation wells shall be as follows. These requirements must be met before the drilling rig is taken from the site.

(1) All new groundwater wells and fresh water observation wells shall be made water-tight around the outside of the production casing by cement grouting to such depths as may be necessary to exclude pollution, but in no case shall the cement grout seals be less than ten (10) continuous feet in depth, provided that five (5) feet of bentonite may be installed immediately below five (5) feet of cement grout for the total 10 feet continuous seal. If surface pipe and production casing are used, the cement grouting and/or bentonite seal shall be installed outside the surface pipe casing in all instances beginning July 1, 2005, provided the following provisions apply:

(A) a variance may be issued by the Director for an alternative completion design due to site specific conditions, and

(B) if a sleeve is used at the surface for the sole purpose of attaching a pitless adapter, the sleeve shall be installed or embedded within the surface seal, extend a minimum of eight feet (8') below ground level in the borehole, and the surface seal shall be a minimum of one and one-half inch (11/2") thick.

(C) If the surface casing does not extend twelve inches (12") above natural ground level and a pitless cap or sanitary seal is not installed, then a ten foot (10') cement grout/bentonite surface seal shall be installed in the area between the surface and production casings terminating within four feet (4') of land surface.

(D) When deemed necessary to utilize conductor or surface casing to control flowing material near surface, an additional cement/bentonite seal shall originate ten feet (10') below the base of the conductor/surface casing and shall terminate ten feet (10') above the base of the conductor/surface casing between the conductor/surface casing and production casing.

(2) The cement or cement/bentonite seal shall originate at a minimum ten (10) foot depth and terminate no deeper than four feet (4') from the natural land surface for a minimum total length of ten feet (10') after all settling of the cement or bentonite/cement has occured, unless a written waiver is first obtained from the Board.

(3) The cement grout shall consist of a mix ratio of one (1) 94 pound sack of cement to a maximum of six (6) U.S. gallons of water. The cement and water must be mixed to the proper consistency as recommended by the cement manufacturer before the mixture is installed around the casing. A maximum of fifty percent (50%) aggregate by dry weight may be added to the port land cement to form the cement grout, provided the aggregate is a size that will not create a potential to cause bridging in the annular space.

(4) A maximum of twenty percent (20%) percent bentonite may be added to the slurry, which bentonite shall be prehydrated to the manufacturer's recommended consistency. Prehydration requires that the bentonite be properly mixed with the recommended amount of water before the mixture is installed.

(5) The well borehole shall be a minimum diameter of at least three (3) inches greater than the outside diameter of the well casing or production tubing adjacent to the borehole utilized in the surface seal.

(6) This annular space shall be filled with cement grout or cement/bentonite to the minimum ten (10) foot depth, or such further depth as may be necessary to exclude pollution.

(7) Where a pitless well adapter or unit is being installed, the grouting shall start below the junction of the pitless well adapter or unit where it attaches to the well casing and shall continue to at least ten (10) feet below this junction.

(8) If a high solids bentonite grout is used for the bentonite seal portion below the cement grout portion of the surface seal, the grout shall contain a minimum, twenty percent (20%) solids by dry weight.

(9) It is not an acceptable installation method to install dry cement around the casing and then add water.

(e)Well development requirements for groundwater wells except sand point wells or fresh water observation wells. Upon completion of the groundwater well or fresh water observation wells and before conducting the yield of drawdown tests, the well driller shall clean and develop the well to remove drill cuttings and drilling mud.

(f)Disinfection of groundwater or fresh water observation wells. Requirements for disinfection of groundwater or fresh water observation wells shall be as follows:

(1) All water used in the drilling of the well shall be potable water or uncontaminated chlorinated water having not less than0.5 milligrams per liter (mg/L) chlorine.

(2) A new, repaired, or modified well shall first be thoroughly cleaned and prepared for receiving pumping equipment.

(3) Thereafter, the well and pumping equipment shall be disinfected with chlorine so applied that a concentration of at least one hundred (100) parts per million of chlorine shall be obtained in all parts of the water in the well.

(4) A minimum contact period of two (2) hours shall be provided before pumping the well to flush chlorine solution from the fresh water distribution system.

(g)Access port or water level measuring device. Upon completion of a new groundwater or fresh water observation well and before the well is put into service, the well driller will equip the well with either an access port that will allow for the measurement of the depth to static water surface or a static water level measuring device.

(h)Sand point well construction requirements. Unless otherwise approved by variance, applicable minimum standards set forth in this section and the following minimum construction requirements apply to sand point wells:

(1) The sand point well shall be drilled to a total depth of no more than thirty feet (30'); and,

(2) A pilot hole shall be constructed first, with cement installed to a depth of three feet (3') around surface casing, then the remaining bore hole can be installed then production casing installed.

Okla. Admin. Code § 785:35-7-1

Amended at 10 Ok Reg 3299, eff 6-25-93 ; Amended at 11 Ok Reg 2947, eff 6-13-94 ; Amended at 12 Ok Reg 2703, eff 7-1-95 ; Amended at 13 Ok Reg 2885, eff 7-1-96 ; Amended at 15 Ok Reg 2440, eff 6-11-98 ; Amended at 19 Ok Reg 2498, eff 6-27-02 ; Amended at 20 Ok Reg 2608, eff 7-11-03 ; Amended at 21 Ok Reg 2632, eff 7-1-04 ; Amended at 22 Ok Reg 1598, eff 7-1-05 ; Amended at 23 Ok Reg 3078, eff 7-27-06 ; Amended at 25 Ok Reg 1444, eff 5-27-08 ; Amended at 27 Ok Reg 1313, eff 5-27-10 ; Amended at 28 Ok Reg 987, eff 7-1-11 ; Amended at 30 Ok Reg 891, eff 6-13-13

Amended by Oklahoma Register, Volume 36, Issue 22, August 1, 2019, eff. 8/11/2019