1. (1) The local health officer shall require an OSS and a reserve area in full compliance with the new construction standards specified in this chapter for an OSS expansion.

2. (2) A local health officer may allow expansion of an existing OSS within 200 feet of a marine shoreline that does not meet the minimum horizontal separation between the soil dispersal component and the ordinary high-water mark required by WAC 246-272A-0210, Table IV, provided that:

   1. (a) The OSS meets all requirements of WAC 246-272A-0230, 246-272A-0232, 246-272A-0234, and 246-272A-0238;
   2. (b) The OSS complies with all other requirements of WAC 246-272A-0210 and this section;
   3. (c) Horizontal separation between the soil dispersal component and the ordinary high-water mark is 50 feet or greater; and
   4. (d) Vertical separation is two feet or greater.

[Statutory Authority: RCW 43.20.050(3), 43.20.065, chapters 70A.105 and 70A.110 RCW. WSR 24-06-046, § 246-272A-0290, filed 3/1/24, effective 4/1/25. Statutory Authority: RCW 43.20.050. WSR 05-15-119, § 246-272A-0290, filed 7/18/05, effective 7/1/07.]