Columbia River Outfall and Effluent Pipeline Project

This project is the culmination of decades of planning to ensure we can meet the region’s long-term wastewater treatment needs and continue safeguarding public health, environmental quality and our community’s economic future. The project will provide an expanded transmission pipeline from the existing Salmon Creek Wastewater Treatment Plant to the Columbia River and improve water quality in the Columbia River.

Project Benefits

The project will:

  • Ensure continued reliable service at a stable, affordable rate by planning for the long-term and avoiding the increased cost of isolated improvements.
  • Provide long-term capacity to support planned growth within the community.
  • Ensure adequate mixing and dilution of treated wastewater discharged into the Columbia River.
  • Manage shoreline stability at the discharge point.
  • Enable future decommissioning of Ridgefield’s aging wastewater treatment plant and outfall into Lake River (after additional projects are in place).

Mailing List

Contact Us

Adrienne DeDona, Public Outreach Manager, can be contacted at (360) 903-4792.

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

Project Overview

Columbia River Outfall and Effluent Pipeline Project Map

The project will build a larger pipeline between the Salmon Creek Wastewater Treatment Plant and the Columbia River, as well as an improved discharge assembly at the river.

The Salmon Creek Wastewater Treatment Plant treats wastewater from approximately 100,000 Clark County residents. All flow received at the plant is treated to a high standard and clean water, or effluent, is conveyed and discharged into the Columbia River via a 30-inch outfall pipeline and submerged diffuser. The Columbia River Outfall and Effluent Pipeline project will plan and build a larger transmission pipeline and improved discharge system. This will ensure continued reliable service at a stable, affordable rate by planning for the long-term and avoiding the increased cost of isolated improvements. The new pipeline and diffuser are needed to provide long-term capacity to support planned growth in the community, as well as to ensure adequate mixing and dilution of treated water discharged into the Columbia River. The project will also improve shoreline stability at the discharge location and eventually lead to decommissioning of Ridgefield’s aging wastewater treatment plant.

The information in this web page is also available as a fact sheet (PDF, 2.4 MB).

Funding

In 2014, the Alliance adopted a comprehensive Capital Plan that brings the partners’ facility assets, including the Salmon Creek Treatment Plant and discharge facilities, under Alliance ownership. Costs for the current phase (planning and preliminary design) are covered in the Capital Plan.

In total, the project is anticipated to cost $20–25 million. As initial phases of the project progress, the full scope and budget will be better known.

What's Happening Now

Special care is being taken to make sure that construction, installation and operation of the new facilities will be environmentally sound, cost-effective, fiscally responsible, and addresses treatment plant neighbor and ratepayer concerns.

We are currently in the initial information-gathering stages of the project, including consulting with key stakeholders through a series of interviews. Input from these interviews will help guide both project design and public outreach.

Diffuser Diagram

An improved diffuser under the Columbia River will ensure that increased discharge of treated water is mixed efficiently and will not harm the environment.

The first planning activities involve establishing information and data to support decisions about pipeline location and design. This includes surveying, geotechnical exploration, environmental analysis, and determining permit and easement needs. The technical work will help determine the design and precise location for the new transmission pipeline and discharge mechanism.

Planning and preliminary design are expected to be complete in early 2017. At that point, there will still be a great deal that needs to be completed before construction can start, including acquisition of the necessary permits and easements, detailed design and engineering, and choosing construction contractors. Cost estimates and financing will also be refined as the process progresses.

Schedule

Outfall Project Schedule

You can also download this schedule (PDF, 103 KB).

Upcoming Events

There are currently no public outreach events planned. The project team is in the process of conducting stakeholder interviews. If you have input on this process, please contact us.

Why This Project is Important

Diffuser Diagram

Reliable, expandable sewer service is essential to our economy and the health of our communities and environment.

Our community has come to expect dependable, affordable sewer services and many people tend to forget how essential wastewater handling is to our quality of life. Our personal health, the community’s economic health, and the health of our rivers and environment depend in large part on treating the wastewater we all generate so that it can be returned safely to the environment.

The Discovery Clean Water Alliance was formed to improve sewer service delivery and stabilize rates for the partners’ customer bases by bringing operation and expansion of treatment/transmission services under joint ownership and allowing for shared decision-making and better long-term planning.

The Clark County General Sewer Plan and Facilities Plans estimate capacity and infrastructure needs over coming years based on future population growth and land use development. These projections indicate that increased wastewater transmission capacity and an improved river discharge facility will be needed by 2022.

Planning and constructing important projects like this takes many years and staying ahead of the expected demand is vitally important. By beginning now, the Alliance ensures that ample wastewater treatment capacity will be in place to continue to provide reliable service at an affordable cost well into our future.