Puget Sound Beach CSO Control Projects

North Beach CSO Control Project

March 2012 Update
Design on the North Beach CSO Control project began in 2011.
>> For current information on this project, view HERE.

Learn more about the decision process and recommended proposal completed in 2010.

Why are CSOs a problem at North Beach?

Like many cities around the country (external link), the older parts of King County's wastewater system carry both wastewater and stormwater to the treatment plant. When heavy rains fill the pipes, excess stormwater and sewage flow directly into Puget Sound near North Beach. These events, called combined sewer overflows, or CSOs, help to avoid sewer backups into homes and businesses and onto streets during storms, but they are a public health and environmental concern. When a CSO happens, about 90 percent of the overflow is stormwater and the rest is dilute sewage.

In 2008, King County reported that the North Beach CSO facility has 10 overflows per year on average that discharge a total of 2.2 million gallons into Puget Sound off North Beach.

King County's goal is to reduce the number of CSOs each year, with a long-term goal of no more than one untreated discharge per location per year on a long-term average to meet state regulations.

Proposed project

King County recommends a project for combined sewer overflow (CSO) control in North Beach

King County plans to design and build an underground storage pipeline in the right-of-way in N.W. Blue Ridge Drive and Triton Drive N.W. This facility will store approximately 230,000 gallons of peak flows when the North Beach Pump Station reaches maximum capacity. After storms have passed, an underground pump will transfer stored flows to the pump station for conveyance to King County’s Carkeek Wet Weather Treatment Facility for transfer to West Point Treatment Plant or onsite treatment.

Schedule

Learn more about the project schedule.