WAC 246-272A-0250. Installation

(1) Only installers may construct OSS, except as noted under subsection (2) of this section. (2) The local health officer may allow the resident owner of a single-family residence to install the OSS for that single-family residence except when: (a) The primary and reserve areas are within 200 feet of marine water; (b) The primary and reserve areas are within 100 feet of surface water; or (c) The installation permit meets Table X standards in WAC 246-272A-0280 . (3) The installer described by either subsection (1) or (2) of this section shall: (a) Follow the approved design; (b) Have the approved design in possession during installation; (c) Make no changes to the approved design without the prior authorization of the designer and the local health officer; (d) Only install sewage tanks approved by the department consistent with chapter 246-272C WAC; (e) Be on the site at all times during the excavation and construction of the OSS; (f) Install the OSS to be watertight, except for the soil dispersal component; (g) Cover the installation only after the local health officer has given approval to cover; and (h) Back fill with six to 24 inches of cover material and grade the site to prevent surface water from accumulating over any component of the OSS.