1707.18 Trenches, Excavation, and Backfill

Excavation for horizontal piping shall comply with Section 1707.18.1 through Section 1707.18.8, Section 1707.8 through Section 1707.11, and in accordance with the requirements of the Authority Having Jurisdiction. Prior to any excavation, trenching, or drilling, all buried utilities including drainage, and irrigation systems shall be located and flagged by the appropriate utility and ground source heat pump system contractor representative.

1707.18.1 Trenches. Trenches for underground piping or tubing shall be excavated in accordance with the setback requirements in Section 1712.4. 1707.18.2 Buried Systems. Buried open-loop system piping, shall be installed not less than 3.3 feet (1006 mm) below the finished grade.

1707.18.3 Pipe Installation. Piping in horizontal trenches shall be embedded with not less than 6 inches (152 mm) of inert granular material above and below, or in accordance with the Authority Having Jurisdiction and project specifications.

Horizontal piping trenching shall be backfilled with approved material and shall be compacted. 1707.18.4 Separation. The horizontal piping shall be separated from fluid-based onsite service systems to prevent excessive short-circuiting heat transfer between such systems.

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1707.18.5 Insulation. Insulation shall be provided on the piping where there is close proximity of all site services to prevent thermal interference between fluid-based onsite service systems. 1707.18.6 Pipe Bends. Sharp bending of pipe shall be prevented or approved elbow fitting shall be used with a bend-radius in accordance with the manufacturer’s

installation instructions.

1707.18.7 Closed Cell Insulation. Buried horizontal open-loop system pipes passing parallel within 5 feet (1524 mm) of a wall, structure, or water pipe shall be insulated with R-2 minimum closed cell insulation.

1707.18.8 Tracer Markings. Means shall be provided for underground detection or utility location of the buried pipe system. This shall include, but is not limited to, metallic detectable tape, with a thickness of not less than 11/64 of an inch (4.4 mm) and a width of 6 inches (152 mm).

This warning marking shall be permanent, conspicuous and resistant to the environmental conditions and shall be placed within 1 foot to 2 feet (305 mm to 610 mm) on top of the horizontal piping of the heat exchanger installation.