Okla. Admin. Code § 785:35-7-1.1

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

Section 785:35-7-1.1 - Minimum standards for construction of heat exchange wells

(a)General requirements.

(1)Applicability of minimum standards. The minimum standards set forth herein apply to all heat exchange wells as defined in 785:35-1-2, whether constructed by a person having a valid license or by any other person. Minimum standards shall include regulation of the drilling of the borehole, installation of casing, installation of heat loop pipe, grouting of the well, and installation of the heat loop pipe up to the connection of the heat loop pipe to the facility circulation equipment .

(2)Prohibition against other uses. Heat exchange wells shall not be used for any purpose other than heat exchange. After completion, heat exchange wells shall not be converted to any other type of well unless written approval is obtained from the Board. The licensee shall ensure that the heat exchange well is constructed according to the rules.

(3)Maximum protection of groundwater required. Construction of heat exchange wells shall provide maximum protection to the groundwater from surface contaminants and movement and migration of water from one zone or aquifer to another.

(b)Location of heat exchange wells.

(1) A vertical heat exchange well shall be located on a site so that surface water will not pool or pond around or within ten (10) feet of the heat exchange well location.

(2) Placement of a heat exchange well must meet or exceed standards as set forth by section 785:35-7-1(b) relating to location requirements for groundwater wells except as set forth in paragraph 3 of this subsection.

(3) If not prohibited by the owner of the well or other federal or state agency requirements, heat exchange wells may be located closer to a possible source of pollution than the minimum distances specified in Section 785:35-7-1(b) if all of the following conditions are met:

(A) The possible pollution source is not a wastewater lagoon, septic tank, absorption field, or aerobic sprinkler system .

(B) The well annulus is completely sealed as described in paragraph 7 of subsection (c) of this section.

(c)Construction standards for vertical closed-loop exchange wells. Vertical closed-loop heat exchange wells shall be constructed in accordance with this subsection. Site specific conditions shall be assessed to determine the best method and materials to be used for grouting the well annulus to provide protection of the groundwater per paragraph 3 of subsection (a) . In addition, but not as an alternative, to the requirements stated in (1) through (8) of this subsection, methods and materials for construction of heat exchange wells that meet or exceed recommendations specified in "Grouting for Vertical Geothermal Heat Pump Systems Engineering Design and Field Procedures Manual", International Ground Source Heat Pump Association, Oklahoma State University, 2015, and in "ANSI/CSA/IGSHPA C448 Series-16, Design and installation of ground source heat pump systems for commercial and residential buildings", American National Standards Institute, 2016, may be used for construction of vertical closed-loop heat exchange wells.

(1)Casing material. If permanent casing is needed in a vertical closed-loop heat exchange well, it must meet standards set out in Section 785:35-7-1 for steel and for plastic.

(2)Heat exchange loop material. The material used to construct the heat exchange loop must meet or exceed standards set forth by Clause 5.4 of ANSI/CSA/IGSHPA C448.0.

(3)Connecting closed-loop pipe. All pipe joints and fittings installed and buried shall meet or exceed standards set forth by Clause 5.4 of ANSI/CSA/IGSHPA C448.0 . Glued or clamped joints shall not be used below ground unless the joint or connection serves as a service outlet and the joint or connection is not covered with earth material. Joints must not leak after assembly. All indoor piping and fittings should meet or exceed standards set forth by Clause 5.5 of ANSI/CSA/IGSHPA C448.0.

(4)Heat transfer fluid. Approved fluids for use inside the heat exchange loop include potable water, food-grade or USP-grade propylene glycol, and solutions in which remediation of leaks would occur through dissipation. A release of the fluid to the groundwater must not violate Oklahoma Water Quality Standards set forth in Chapter 45, OAC 785.

(5)Borehole specifications.

(A)Borehole diameter. The borehole for vertical closed-loop heat exchange wells must have a sufficient diameter to accommodate the heat exchange loop u-bend assembly, tremie pipe, and placement of grout to surround all heat exchange loop pipe.

(B)Exploratory borehole. The first borehole drilled for the vertical closed-loop heat exchange system shall be considered an exploratory borehole. A subsequent borehole may also be considered an exploratory borehole if the well driller encounters subsurface conditions that include, but are not limited to, lost circulation conditions, hydrocarbons or hazardous gases, and changes in groundwater chemistry.

(C)Lost circulation conditions. If caves or large fractures are encountered in drilling the exploratory borehole or any subsequent borehole, grouting may not be possible and the Board must pre-approve completion of the vertical closed-loop heat exchange system in such conditions based on plans to bridge and seal zones of lost circulation.

(D)Hydrocarbons and hazardous gases. If hazardous gases or hydrocarbons are observed in drilling the exploratory borehole or any subsequent borehole, the Board must be notified immediately. Completion of the vertical closed-loop heat exchange system shall be prohibited without Board approval.

(E)Groundwater chemistry. Chemistry of groundwater encountered in drilling the exploratory borehole, or any subsequent borehole shall be used to inform grout selection. Instructions provided by the grout manufacturer must be followed to provide protection of the groundwater per paragraph 3 of subsection (c) of this section. The grout manufacturer shall be consulted as required.

(6)Grouting of vertical heat exchange wells. Grouting and filling the annulus of a heat exchange well must be completed immediately after the well is drilled to avoid cave-in of the uncased hole.

(7)Grouting methods and materials for vertical closed-loop heat exchange wells. Grouting methods for vertical closed-loop heat exchange wells shall meet or exceed standards provided by Clause 5.8 of ANSI/CSA/IGSHPA C448.0 and Clause 6.3 of ANSI/CSA/IGSHPA C448.3 except where standards set forth by this Section provide exceptions. The following methods and materials are approved for grouting the annulus of vertical closed-loop heat exchange wells, provided that standards set forth by 785:35-7-1.1(c)(5)(E) shall also apply:

(A) A grout seal shall be installed from the total depth of the borehole up to the connecting trench and must be composed of one of the following materials:

(i) Portland cement;

(ii) Sand-cement mixed at a ratio of not more than 188 pounds of sand to one 94-pound sack of Portland cement and seven (7) gallons of water;

(iii) High solids bentonite grout with a minimum solids content of 20 percent by weight. Clean silica sand may be added to the slurry;

(iv) Bentonite pellets or chips; or

(v) Approved thermally enhanced grouts and non-cement grouts which meet standards set forth by Clause 5.8 of ANSI/CSA/IGSHPA C448.0 and Clause 6.3 of ANSI/CSA/IGSHPA C448.3

(B) Bentonite chip or pellet fill material installed shall be hydrated immediately after installation if installed in the unsaturated zone.

(C) When non-slurry sealing materials are used, only chipped or pelletized sodium bentonite varieties that are designed to fall through standing water are acceptable when sealing the annulus of a well that is below the water level in the saturated zone. The borehole shall be flushed clean of all drilling mud and debris left over from the drilling operation so that the bentonite products designed for this type of installation will gravity feed without obstruction. Material shall be introduced in a manner to prevent bridging of the materials in the borehole annulus. A measuring device such as a tagline shall be used to measure and document placement of the materials installed.

(D) Slurry mixes of bentonite grout or Portland cement shall be installed by pumping through a tremie pipe in a continuous operation using a positive displacement method. Polymer additives designed to retard swelling are acceptable for use with the bentonite grout or Portland cement. The tremie pipe will extend the full depth of the borehole before pumping begins. The borehole diameter shall be of adequate size to allow proper placement of materials using this method. Slurry volume used must equal the annulus volume of the borehole.

(8)Concentric tube heat exchangers. Concentric tube heat exchangers that meet or exceed the requirements of this Section are approved.

(d)Construction standards for open-loop and return heat exchange wells.

(1) Groundwater wells and water return wells used in open-loop heat exchange must meet the minimum construction standards set forth in Section 785:35-7-1 relating to groundwater.

(2) Groundwater used in the open loop heat exchange system must remain untreated and be returned to the same aquifer from which the groundwater was withdrawn.

(e)Construction standards for horizontal closed-loop heat exchange systems. Horizontal closed-loop heat exchange systems constructed by trenching or digging are exempt from grouting requirements, provided that no part of the horizontal loop is constructed at or below the highest anticipated groundwater level. Horizontal closed-loop heat exchange systems constructed by boring or drilling must be grouted according to standards set forth by paragraph 7 of subsection (c) of this Section. All other construction for horizontal closed-loop heat exchange systems shall meet or exceed standards set forth by subsection (c) of this Section.

Okla. Admin. Code § 785:35-7-1.1

Added at 20 Ok Reg 2608, eff 7-11-03; Amended at 21 Ok Reg 3169, eff 7-25-03 through 7-14-04 (emergency)¹; Amended at 21 Ok Reg 3180, eff 9-13-04; Amended at 23 Ok Reg 3078, eff 7-27-06; Amended at 25 Ok Reg 1444, eff 5-27-08

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

¹This emergency action expired without being superseded by a permanent action. Upon expiration of an emergency amendatory action, the last prior permanent text is reinstated. Therefore, on 7-15-04 (after the expiration of the emergency action), the text of section 785:35-7-1.1 reverted back to the permanent text that became eff 7-11-03, as was last published in the 2003 OAC Supplement, and remained as such until amended again by permanent action on 9-13-04.