Salmon Creek Treatment Plant Odor Control and Existing Facilities Improvements

The treatment plant is a vital part of the wastewater system - helping to keep our community livable and protect the environment. This project will improve odor control and operational reliability for the facility.

Learn more about the construction taking place at the Salmon Creek Treatment Plant.

Project Overview

The Salmon Creek Wastewater Treatment Plant receives and treats approximately 8–10 million gallons of wastewater per day from homes and businesses. All wastewater received at the plant is treated to a high standard before clean water, or effluent, is conveyed and discharged into the Columbia River. As the plant ages, several areas of the in-plant mechanical systems will be renovated to keep the facility operating efficiently and in good working order. Improvements will also be made to the odor control systems to treat sources of odorous air before discharge to the atmosphere. Lastly, a new structure will be built to house stored materials and an older structure will need to be demolished to make space for future new facilities.

The information in this web page is also available as a fact sheet (PDF).

Odor Control

Although our operators take great care in minimizing odors by keeping the treatment processes balanced and operating in a healthy manner, some odors do occur as a result of regular operations. We are undertaking this improvement project to eliminate about 80-90% of the odors nearby neighbors may experience currently. The new equipment will capture and treat the odor that is generated as a result of regular treatment operations; however, some odor generating events will still occur that will result in minor odor releases from time to time, such as when basins are taken off-line for cleaning and repair.

This project includes installation of new odor control systems at the front and back ends of the plant. On the front end, new biotrickling filters will treat air from the preliminary treatment and primary treatment processes. In order to help collect the air for treatment, new aluminum covers will be added over the Primary Clarifiers. On the back end, new carbon adsorbers will treat air collected from the solids treatment process. These methods have proven very effective in reducing odors and the technologies were selected to specifically treat odors generated at each end of the facility.

Salmon Creek Treatment Plant Odor Control and Existing Facilities Improvements


Planning, design and construction costs for the project are covered in the Alliance’s Capital Plan, which includes funding for all long-range planning projects such as this one. In total, the project is anticipated to cost approximately $12 million. Those costs are allocated to the Alliance partners that share ownership of the facility – the City of Battle Ground and the Clark Regional Wastewater District.


Construction is slated to begin in 2020 and be completed sometime in 2021. There is a great deal that needs to be completed before construction can begin, including detailed design and engineering, acquisition of the necessary permits, and selecting a construction contractor through a competitive bid process. Permitting and Design are ongoing, and should last through the end of 2019.

Salmon Creek Phase 5 Program Delivery Timeline

Construction Impacts

The construction of new odor control systems and improvements to existing facilities at the treatment plant is scheduled to start in early 2020. Traffic bringing workers and materials into the plant will increase during this period, with levels varying based on the work planned for any particular day. Construction management staff will be on-site to ensure that the Contractor is in compliance with County standards for hours of operation and noise. More information will be made available as the project design is completed toward the end of 2019.

Frequently Asked Questions

We have received many questions related to this project. Please see Frequently Asked Questions and Responses. If you have a question that is not included in this document, please contact us below and we would be happy to provide an answer.

Contact Us

Dale Lough, Alliance Capital Program Manager, can be contacted at (360) 993-8856, or

Project information can be provided in other formats or languages upon request.