OAR 690-240-0043: Construction Standards

(1) If permanent casing is needed in a ground source heat pump boring, it shall meet the standards set out in OAR 690-210-0190 through 690-210-0220 for steel and plastic. (2) Site specific conditions shall be assessed to determine the best method and materials to be used for sealing the boring annulus to protect the groundwater resource and that method shall meet the standards set out in OAR 690-210-0300 through 690-210-0360 for sealing wells. (3) The diameter of the borehole for cased and uncased ground source heat pump borings shall allow placement of the heat exchange loop and grout pipe to the bottom of the boring as follows: (a) For installation of a 3/4 inch loop, the diameter of the borehole shall be a minimum of 4 inches; (b) For installation of a 1 inch loop, the diameter of the borehole shall be a minimum of 4 1/2 inches; and (c) For installation of a 1 1/4 inch loop, the diameter of the borehole shall be a minimum of 5 inches. (4) The type of sealing material used shall be compatible with the heat exchange loop material and permanent casing material used in the construction of the boring.