Bored Geothermal Heat Exchanger (BGHE) and Groundwater Thermal Exchange Device (GTED) Construction Permit Applications

Instructions for obtaining a BGHE construction permit

Minnesota Statutes, chapter 103I authorizes the commissioner of health to issue permits for the construction of bored geothermal heat exchangers. This includes any earth-coupled heating or cooling device consisting of a sealed pipe system installed into a boring to transfer heat to or from the surrounding earth. This does not include a closed-loop piping system installed in a boring 15 feet or less below the established ground surface. Minnesota Rules, chapter 4725 "Wells and Borings" establishes the permit application requirements and the standards for the construction, maintenance, and sealing of BGHEs.

Requirements

• A completed application form must be submitted to the Minnesota Department of Health (MDH), along with the appropriate fee and the required documentation for approval. In most cases, the licensed well contractor or licensed bored geothermal heat exchanger contractor fills out and submits the application. The fee is nonrefundable.
• The BGHE must be constructed by a licensed well contractor or licensed bored geothermal heat exchanger contractor.
• The construction, maintenance, and sealing must be in compliance with Minnesota Rules, chapter 4725.
• The owner agrees to allow inspection of the system by MDH during regular business hours.
• The owner of the BGHE must notify MDH of heat loop fluid leakage or loss of pressure within 24 hours after the owner becomes aware of the loss or leak.

Standards

In order to protect the quality of the groundwater resources of the state, MDH will review permit applications to determine compliance with the following standards:

1. BGHE piping must be a high density polyethylene or cross-linked polyethylene (PEXa) that meets the standards and requirements of Minnesota Rules, part 4725.7050, subpart 1, item A. The pipe must have a minimum pressure rating of 160 pounds per square inch (psi) at 73 degrees Fahrenheit.
2. BGHE pipe connections must meet the standards and requirements of Minnesota Rules, part 4725.7050, subpart 1, item A .
3. BGHE piping must have a successful pressure test after the piping is installed. Piping must be pressure tested with potable water at a pressure of 1.5 times the system operating pressure or 100 psi, whichever is greater. The pressure must remain constant for 30 minutes without adding water.
4. The annular space between the BGHE piping and the bore hole must be grouted according to the procedures in Minnesota Rules, part 4725.3050, subpart 2. Rock portions of the bore hole must be grouted with neat-cement or cement-sand grout. Portions of the bore hole in unconsolidated formations must be grouted with bentonite grout, thermally enhanced bentonite grout, neat-cement grout, or cement-sand grout.
5. Minnesota Rules, part 4725.7050, subpart 1, item D allows food-grade or United States Pharmacopeia (USP) grade propylene glycol, and ethanol products designed to be used in BGHE systems. A propylene glycol with additives, including corrosion inhibitors and dyes, may be used as a heat transfer fluid if it is certified as meeting the NSF Category Code HT1. Ethanol products must be designed by the manufacturer for use in BGHE systems and must not be used unless approved in writing by MDH. A permanent sign must be attached to the heat pump specifying that only approved heat transfer fluids must be used.
6. A water make-up line to the bored geothermal heat exchanger must be protected with a backflow prevention device as required by the Minnesota Plumbing Code, Minnesota Rules, chapter 4714.

Application

• BGHE Construction Permit Application Form (PDF)

Instructions for obtaining a GTED construction permit

Minnesota Statutes, chapter 103I authorizes the commissioner of health to issue permits for the construction of groundwater thermal exchange devices. A GTED is a heating or cooling device that depends on extraction and reinjection of groundwater from an independent aquifer to operate and includes a water-supply well used to withdraw or inject water.

Requirements

• A GTED must be installed by a MDH-licensed well contractor.
• A completed application must be submitted to MDH, along with the appropriate fee and the required documentation for approval. In most cases, the licensed well contractor fills out and submits the application. The fee is nonrefundable.
• The water-supply well(s) used to operate the GTED must be constructed in accordance with the construction requirements for non-potable water-supply wells in Minnesota Rules, chapter 4725.
• A GTED also requires a water appropriation permit from the Minnesota Department of Natural Resources (DNR) if more than 10,000 gallons per day or a million gallons per year is withdrawn. For more information from the DNR, visit: Water Use Permits.

Application

• Permit Application to Operate a GTED Form (PDF)
• GTED Sample Piping Diagram (PDF)

Questions

Well Management Section
651-201-4600 or 800-383-9808
health.wells@state.mn.us

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