North Beach Pump Station and CSO Control Project

As part of its mission to protect public health and the environment, King County is responsible for conveying and treating wastewater collected by 34 local city and sewer agencies, including the City of Seattle.

Upgrades needed to North Beach Facilities

King County has operated a pump station and sewer line in the North Beach area for more than 40 years. These aging facilities need to be upgraded to provide safe and reliable operations and capacity for the future. The North Beach Pump Station does not meet current county design standards or building and seismic codes. The station also has no odor control unit.

The North Beach force main sewer conveys wastewater from North Beach Pump Station to the Carkeek Pump Station. From there, wastewater goes on to the West Point Treatment Plant. The pipe needs to be evaluated to determine its condition. Because of its location in the tidal area of Puget Sound, access to the pipe and maintenance are difficult. The existing single pipe may not provide adequate capacity for the future.

Reducing Combined Sewer Overflows (CSOs) at North Beach

During heavy rains when flows exceed the capacity of the sewer system, the system can overflow into Puget Sound at North Beach. When this happens, about 90 percent of the combined volume of the overflow is storm water and the rest is diluted sewage. These events are called combined sewer overflows, or CSOs. CSOs help to avoid sewer backups into homes and businesses and onto streets during storms. Between June 2000 and May 2007, the North Beach CSO discharged on average 9 times each year, a total of 2.2 million gallons per year.

CSOs are a public health and environmental concern because untreated wastewater and storm water may be discharged to Puget Sound during large storms. King County’s goal is to reduce the number of CSOs each year, with a long-term goal of less than one untreated discharge per location per year to meet state regulations.

To protect Puget Sound and meet our goal, the county is identifying CSO control options for North Beach, West Seattle, and South Magnolia. These locations are top priority because people are most likely to come in contact with water during recreational activities such as swimming.

The map shows the area draining to North Beach and nearby facilities. At North Beach, CSO control options may include:

• Storage of peak flows during large storms. Once the storm passes, flows would be sent to West Point Treatment Plant. This option would involve constructing a storage tank or pipe in the North Beach drainage basin.
• Pumping more of the flows out of the basin by increasing the capacity of the North Beach Pump Station, force main, and downstream facilities. This option may also involve managing these CSO flows at the Carkeek CSO treatment plant.
• Reducing flows of storm water and ground water into the wastewater collection system. The county will work with the City of Seattle to find ways to reduce flows into the city or county system.
• Treatment of peak flows during large storms. This option would involve constructing a local CSO treatment facility in North Beach that would operate only a few times a year.

These options can be used alone or in combination, depending on local conditions at North Beach.

Schedule

Your comments and ideas are welcome

The county is committed to working with the local communities to evaluate alternatives and address suggestions and concerns. We will work with the public to identify potential community and environmental impacts early in the environmental and design review processes. Our public information and involvement program will continue throughout design, construction and operation of the facilities.

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For more information

• For more information or to be added to the project mailing list, please call Jennifer Kauffman at 206-263-6029 or 711 TTY Relay or e-mail jennifer.kauffman@kingcounty.gov
• Visit the CSO Control Program Web site

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Department of Natural Resources and Parks
Wastewater Treatment Division
201 S. Jackson St.
Seattle, WA 98104-3855
Fax: 206-684-1278

Updated: April 15, 2008

WTD Construction Projects

CSO Control Program