41.20.110 Installation.
(1) The Health Officer shall require approved installers to construct OSS, except as noted under subsection (2) of this section. Licensed installers shall meet all requirements of this chapter and install systems as per WAC 246-272A-210.
(2) The Health Officer may allow the resident owner of a single-family residence not adjacent to a marine shoreline to install a conventional gravity-type OSS for that single-family residence if they meet all the following:
(a) May install no more than one system in any one calendar year.
(b) The OSS installer owns or has a beneficial interest as a contract purchaser of the land on which the OSS is to be installed.
(c) The OSS is either located on the same lot as the residence or situated on adjoining property controlled by the owner and legally listed as an encumbrance.
(d) The OSS installer will reside in or use the building served by the OSS.
(e) The Health Officer may require written examination of resident owners when considering applications for self-installation.
(3) Persons engaged in the business of buying, selling, and constructing homes or land shall not qualify.
(4) All persons employed to construct, install, or alter a sewage disposal system shall be employees of a licensed installer.
(5) 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 licensed designer and the Health Officer;
(d) Only install septic tanks, pump chambers, and holding tanks approved by the WDOH;
(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 Health Officer has given approval to cover; and
(h) Backfill with six to 24 inches of cover material and grade the site to prevent surface water from accumulating over any component of the OSS.