Treatment Improvements

The Willow Lake Wastewater Treatment Plant Facilities Plan (Facilities Plan) identifies conveyance and treatment facilities needed to address sanitary sewer overflows (SSOs) and to treat existing and future wastewater flows through the year 2025. Under the Facilities Plan, conveyance and treatment alternatives identified in the 1996 Wastewater Management Master Plan (1996 Master Plan) were evaluated, as well as other alternatives developed by the facilities planning team.

Sanitary sewer overflows (SSO) are those flows released from the conveyance system when its capacity is exceeded. Sanitary sewer overflows occur in Salem during periods of high rainfall when dilute raw sewage is released from the system. Oregon water quality regulations disallow SSOs for rainfall events less than the 5-year, 24-hour winter storm and 10-year, 24-hour summer storm. The winter regulatory storm, which is defined as 2.7 inches of rain in a 24-hour period for Salem, governs facility requirements.

The timeline set forth in the Facilities Plan for conveyance and treatment facilities is governed primarily by deadlines set forth in the 1998 Mutual Agreement and Order (MAO) between the City of Salem and the State of Oregon, Department of Environmental Quality (DEQ). The MAO established the following deadlines to eliminate SSOs resulting from the design storm:

• Completion of collection system improvements to eliminate SSOs to tributary streams by January 1, 2000.
• Completion of collection system improvements to eliminate newly discovered SSOs to tributary streams by January 1, 2005.
• Elimination of SSOs to the Willamette River by December 31, 2009.

The City has met the 2000 MAO deadline and is working toward the 2005 and 2009 deadlines. The timeline for improvements outlined in the Facilities Plan allows the City to comply with the 2005 and 2009 deadlines. The Program provides for investing approximately $400 Million over the next 12 years in the conveyance and treatment facilities. This approach of spreading the costs over the 12-year period allows for compliance with the MAO, while minimizing the impact to rates. You may access the Facilities Plan by using the links below.

The initial projects in Phase 1 of the Program have begun and you may get additional detail regarding those projects by using the links below.

If you have questions regarding the Program, please contact Keith Whisenhunt, PE, Assistant City Engineer, at 503-588-6211 or kwhisenhunt@cityofsalem.net.

Current Projects

• Downtown Interceptor
• PEFTF (Peak Excess Flow Treatment Facility)
• Willow Lake Water Pollution Control Facility (Willow Lake WPCF) Schematic Design
• Process Support Facilities

Additional Information

• Willow Lake Treatment Plant Facilities Plan - Currently unavailable online.
• Willow Lake Wastewater Treatment Plant Facilities Plan Presentation
• Willow Lake WPCF Design Standards
• Willow Lake WPCF Master Guide Specifications
• Willow Lake WPCF Drawings Library