Kitsap County Meets the Challenges of Optimizing a $150M Wastewater Facility Plan

Kitsap County, WA occupies the majority of the western shore of Puget Sound and is home to a fast-growing population of more than 250,000 residents. Given the ecological importance of Puget Sound, planning the 20 year wastewater infrastructure needs of this region presented some difficult challenges including handling increasing flows from a growing service area, meeting strict regulatory requirements, protecting aquatic resources, and minimizing the required capital investment.

One of the basic objectives of the Central Kitsap Facility Plan was to evaluate the collection system for existing deficiencies, and to identify improvements needed to serve population growth over the 20-year planning period that would provide the best return on investment.

The 2025 scenario resulted in identification of significant improvements throughout the existing collection systems. Numerous model runs with MIKE URBAN were performed to identify improvements which included siphon upgrades that would convey the increase in flows, while avoiding replacement of a key section of the siphon under an existing stream. The model verified this goal was attainable, and furthermore, helped to establish the feasibility of avoiding a very large pumping station that had previously been proposed.