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Big Gulch Project
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Current
Situation - The South Fork of Big Gulch Creek crosses
under Harbour Pointe Blvd near the Mukilteo Library. It then flows
north and west until it reaches Puget Sound. An 8,600 foot long
sanitary sewer line to the District’s wastewater treatment
plant, constructed below ground in 1969, begins near the Mukilteo
Library and continues down the ravine adjacent to the creek in
the South Fork until it reaches the treatment plant at Puget Sound.
Due to erosion over the years it is currently exposed in many
areas (as seen in the photo to the left) and is subject to washout
and surface water entering the pipe. |
| Manholes are
sitting at significantly higher elevations than the adjacent creek
bed, exposing the infrastructure to damage caused by rocks and
debris. This creates unstable conditions for the pipe and manholes,
and exposes the environment to potential sewage spills. |
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Proposal Description - A Facilities Plan, completed in 2001, evaluated five alternatives for addressing the problem and recommended that the sewer line be replaced with a new pipe along the same or a similar route. The report and its finding were approved by the Washington State Department of Ecology on June 5, 2001. This project also includes constructing a stormwater bypass pipe, carrying only excess runoff, alongside the sewer line to convey high storm water runoff flows through Big Gulch to the Sound to minimize further erosion in the gulch. Drainage areas contributing storm water to the bypass pipeline include upper Big Gulch at Paine Field, Big Gulch within the City of Mukilteo, and a segment of Smuggler’s Gulch. The exact route of the high flow bypass pipe is not yet determined. Project Proponents – The lead proponent of this project is Olympus Terrace Sewer District. It owns the wastewater treatment plant and sewer pipeline. The District is proposed to fund 50% of the project. The sewer line is located within the City of Mukilteo, which is proposed to fund 25% of the project. Paine Field, which is under the auspices of Snohomish County, proposes to discharge excess runoff from a portion of its property, which presently flows down an adjacent ravine called Smuggler’s Gulch to the high flow stormwater bypass line. Snohomish County is proposed to fund 25% of the project. The Next Step – The next phase of the
project is slated to begin in early 2005. A pre-design report
will be prepared by project engineers from Hammond Collier Wade
Livingstone that reviews in detail the construction, environmental,
and permitting issues, and goes on to develop detailed design
concepts. |
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Additionally, an evaluation concerning the possible construction of a Pedestrian Trail is included within the project scope. Such a trail would enable public access to the ravine and beach. The District is proud to be working with its partners toward an enhanced solution to the challenging situation within the Gulch. Together we are not just working to replace a critical sewer line, but to improve the current condition of the Gulch to make it more resistant to damaging high surface water flows. |
| For questions or comments regarding the Big Gulch project, email , or call him at 425-353-6000. | |
