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D.C. Municipal Regulations (Last Updated: September 13, 2017) |
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Title 21. WATER AND SANITATION |
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Chapter 21-18. WELL CONSTRUCTION, MAINTENANCE, AND ABANDONMENT STANDARDS |
Section 21-1823. WELL CONSTRUCTION REQUIREMENTS: CLOSED-LOOP GROUND SOURCE HEAT PUMP WELL
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1823.1A closed-loop ground source heat pump system shall contain pipes, loops, or loop configurations that meet the requirements of this chapter.
1823.2Unless otherwise specified in this chapter, closed-loop ground source heat pump well exchanger pipe and fitting materials shall meet the standards and specifications in the document Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, Revised Edition 2008, published by the International Ground Source Heat Pump Association, Oklahoma State University, which is adopted and incorporated by reference.
1823.3All closed-loop ground source heat pump well exchanger pipe and fitting materials shall be stenciled with the applicable American Society for Testing and Materials (ASTM) standard.
1823.4If a closed-loop ground source heat pump well exchanger pipe and fitting materials do not meet the requirements of § 1823.2, the proper documentation of manufacturer specifications shall be supplied to the Department in the well construction work plan for approval.
1823.5A closed-loop ground source heat pump system installer and licensed well driller shall be experienced, trained, certified, or accredited by a recognized professional organization specializing in the installation of ground source heat pump systems.
1823.6A closed-loop ground source heat pump well and system shall not be designed or operated in a manner to allow system heating or cooling of soil, rock, or water beyond the property line where the well is sited.
1823.7Permanent casing shall be used for a closed-loop ground source heat pump well sited on a property where a recognized environmental condition has been identified.
1823.8Permanent casing for closed-loop ground source heat pump wells shall be constructed of new steel where organic contaminants are present.
1823.9A closed-loop ground source heat pump well shall be constructed with a high density polyethylene (HDPE) factory manufactured pipe forming a loop, and shall be grouted in accordance with § 1818.15.
1823.10Pipe joints and fittings installed and buried shall be socket or butt thermally fused or electro-fused according to the pipe manufacturer’s specifications.
1823.11Glued or clamped pipe joints shall not be used below ground.
1823.12Dimensions for closed-loop ground source heat pump systems shall meet the following requirements:
(a)A pipe with a diameter of less than one and one quarter inch (1.25 in.) (3.175 cm) (nominal) shall be manufactured in accordance with ASTM D-3035 with a minimum (based on pressure rating) dimension ratio of 11;
(b)A pipe with a diameter from one and one quarter inch (1.25 in)(3.175 cm) (nominal) up to three inches (3 in.) (7.62 cm) in diameter shall be manufactured in accordance with ASTM D-3035 with a minimum (based on pressure rating) dimension ratio of 11; and
(c)A pipe with a diameter of three inches (3 in.) (7.62 cm) (nominal) and larger shall be manufactured in accordance with ASTM D-3035, with a minimum (based on pressure rating) dimension ratio of 17 or D-2447 (Schedule 40).
1823.13The closed-loop ground source heat pump boring diameter shall be a minimum of four inches (4 in.) to sufficiently allow the placement of grout using a tremie pipe and the heat exchanger loop piping.
1823.14Flushing, purging, pressure, and flow testing of closed-loop ground source well and system components shall meet the following requirements:
(a)The loops shall be pressure tested before installation;
(b)All horizontal components of the ground heat exchanger shall be flushed, pressure tested, and flow tested prior to backfilling;
(c)The heat exchangers shall be tested hydrostatically at one hundred and fifty percent (150%) of the pipe design rating or three hundred percent (300%) of the system operating pressure, if this value is the smaller of the two; and
(d)No visible leaks shall occur within a thirty (30) minute period.
1823.15All buried pipes and plumbing shall be marked with underground warning tape at a depth of twenty-four inches (24 in.).
1823.16All closed-loop ground source heat pump system piping shall be capped and protected until the manifold piping is ready to be connected.
1823.17All closed-loop ground source heat pump system piping shall be connected to the building in accordance with the manufacturer’s recommendations and all local building and plumbing codes.
1823.18The solution contained in a closed-loop ground source heat pump well piping system shall not contain any substances that pose a hazard to the public health and safety or the environment and shall be:
(a)Potable water; or
(b)A food-grade quality antifreeze solution that is non-toxic, non-corrosive, long-lasting, and that does not exceed twenty percent (20%) antifreeze in solution.
1823.19Pressure testing of the closed-loop ground source heat pump system network shall be conducted prior to putting the system into operation.
1823.20No person shall install any other type of ground source heat pump system not specified in this chapter unless approved by the Department in the well construction work plan.
1823.21A person requesting the use of materials or procedures that differ from those provided in this section shall provide documentation demonstrating that the substitute materials or procedures are in compliance with relevant District construction codes and International Ground Source Heat Pump Association standards, and that such use would provide an equivalent material strength and durability.
1823.22The construction of an open-loop ground source heat pump system shall be prohibited.