Indian Health Services (IHS) Makah Sewer Outfall, Neah Bay, WA

The existing Sewer Outfall pipe (the portion of the pipe in the sea) was constructed in 1995. The 14’’ diameter high density polyethylene pipe (HDPE) extends about 3,500 ft from the shore into the Strait of Juan de Fuca, along the bottom of the bay, and ends at a depth of about 45 ft of water. Previous pipe anchor repairs were performed on the outfall pipe in 2016 where they repaired the anchors using revetment blankets to keep the pipe secured to the sea floor.

On 21 May 2021, an inspection of the sewer outfall identified that a short section (estimated to be 260 ft) of the foreshore sewer outfall had broken free from the anchorage and was floating. A subsequent site inspection performed by IHS on 22 July 2024 determined that the floating pipeline was no longer present and had completely broken free. USACE performed a survey to collect bathymetry data on 19 September 2024 to identify gaps in the pipe. It has been determined that the pipeline will be replaced. Period of Performance (POP) is expected to be 120 days.

The project will replace 2,800 LF of HDPE, from flange stationed at 8+60 to diffuser stationed at 35+80, with an anchor structure designed to withstand the tidal forces of the area.