North Beach Pump Station and CSO Control Project

King County to begin the alternatives selection process for CSO Control in the North Beach basin

To protect Puget Sound and public health, King County is identifying CSO control options for Barton, Murray, North Beach, 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.

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North Beach CSO basin area

King County has identified several approaches to CSO control for these projects. These include the following:

Conveyance/treatment --Sending flows from the basin to a regional treatment plant.
Storage --Retaining flows during storms to prevent CSOs. Following the storm event, flows are sent for secondary treatment following the event.
On-site treatment --Providing primary treatment for flows exceeding system capacity during large storms.
Demand management (stormwater flow reduction) --Implementing one or more methods of limiting stormwater flow into the sewer system.
Combination of approaches--These options can be used alone or in combination, depending on local conditions at North Beach.

Beginning fall 2009, King County’s CSO Beach Project team will begin work to evaluate alternatives, approaches combined with potential sites, for CSO Control projects in all four basins.

Why are CSOs a problem 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 protect sewer facilities and avoid sewer backups into homes and businesses and onto streets during storms. On a 7-year average, the North Beach CSO discharged on average 10 times each year, a total of 2.2 million gallons per year.

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. The county is in the process of identifying CSO control approaches for North Beach, as well as for three other locations on Puget Sound: Barton and Murray (in 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.

Schedule

Evaluate alternatives for CSO control: 2009-2010
Alternative selection and environmental review: December, 2010
Final design & permitting: 2011-2013
Construction: Begins late 2013

How you can participate in the alternatives selection process

Check the Web – People can watch this Web page for updated information and announcements of community meetings
Sign up for updates – You can join our listserv to get notices when community meetings and updates are posted for each basin
Give us your input – Learn about alternatives being developed for each basin and provide input during the selection process

Related information

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.
As part of the identification and evaluation of the CSO alternatives upgrades to the North Beach Pump Station and force main will be evaluated, as well.