Chapter 24 is of the IRC® 2018 adopted with the following modification: Section G2415.12 Minimum burial depth. This section has been modified to require all underground piping systems to be installed a minimum of 18 inches below grade. This section has been revised to read: G2415.12 Minimum burial depth. Underground piping systems shall be installed a minimum depth of 18 inches (457.5 mm) below grade, except as provided for in Section G2415.12.1.
Okla. Admin. Code § 748:20-6-29