RH2 was retained to expand the capacity of the Kitsap Peninsula’s Joint Wastewater Treatment Facility in response to population growth pressure. The Washington State Department of Ecology would only allow expansion providing that the mass loading being discharged did not increase above the original limits and that extreme wet weather flows up to 16.0 MGD received treatment equivalent to secondary treatment quality. In addition, Ecology required that provisions be made for nutrient removal.
The processes used to expand the capacity of the facility needed to produce a high-quality effluent on an extremely small site.
The membrane bioreactor process is capable of treating municipal wastewater to a very high quality, reducing BOD to less than 5.0 mg/l, TSS to less than 1.0 mg/l and the E. coliform to less than normal application of chlorine. This work also revealed that a ballasted clarifier could reduce the BOD by 60 percent and the TSS by 90 percent.
Design and construction were completed in phases. Since start-up, the facility has proven capable of meeting the requirements of the discharge permit. The final design and construction has provided for further expansion of the plant in stages to maximize month flows of 4.8 MGD and beyond.