Wastewater Facilities Plan
South Suburban Sanitary District, Oregon

The District operates a plant with four large lagoons followed by disinfection prior to discharge to the Klamath River. It was anticipated that the nutrient Total Maximum Daily Loads (TMDLs) to the Klamath River would result in some of the most stringent treatment requirements in the state. West Yost prepared the facilities plan in response to preliminary TMDLs that were being developed for the Klamath River. The initial draft of the facilities plan was completed. An initial assessment of the treatment plant indicated that for the short term, supplemental aeration was needed in the lagoons, especially during cold weather when the lagoons could freeze. In addition, improvements to the preliminary treatment system were identified.The District retained West Yost to design a new 32 mgd headworks including a new influent pumping station and a screening facility. Also, aeration was added to the lagoons to prevent freezing and to increase the oxidation capacity. The new influent pumping station, headworks, blower building, and lagoon aeration are now in operation.

Long term alternatives developed and evaluated for the facilities plan included year-round effluent reuse, advanced wastewater treatment, a combination of dry-weather reuse and wet weather discharge and wetlands treatment. At this time, the Department of Environmental Quality has provided preliminary treatment requirements including phosphorous, ammonia and nitrogen removal, and more stringent BOD5 requirements. The District has retained West Yost to update the Facilities Plan in response to the TMDLs.