King County to replace Lincoln Park sewer line
King County will start this weekend on a four-month construction project to replace more than a mile of sewer line that runs through West Seattle's Lincoln Park. The 50-year-old line was damaged after heavy rains and high flows on Jan. 17 and Feb. 6, causing sewage leaks in Lincoln Park (links).
The county decided to replace the line after Wastewater Treatment Division inspectors discovered extensive wear and corrosion throughout much of the pipe, which pushes wastewater from the Barton Street Pump Station north of the Fauntleroy ferry dock through a 6,250-foot pipeline to the county's Murray Avenue Pump Station at Lowman Beach Park.
To keep the system operating normally during construction, crews installed a temporary 6,000-foot-long, 18-inch-diameter surface pipeline along the beach to carry wastewater from an interim pumping facility at Barton to a manhole south of Lowman Park where it will be discharged back into the system and go to the West Point Treatment Plant in Seattle.
When the temporary pipe and pumping station begin operating this weekend, the county will no longer need to bypass the damaged line using trucks to haul wastewater from Barton to the Alki Treatment Plant. The temporary pipe will also enable the county to stop bypassing about a million gallons of wastewater a day to an outfall in Puget Sound, which will protect water quality.
Contractors will begin permanent repairs next week, installing a new, 24-inch plastic pipe inside the existing line, which will take about a month. Lining the old pipe is more efficient and cost-effective because the old pipe will not need to be dug out and removed.
When the pipe lining work is finished, the system will once again begin normal operations and the temporary equipment will be removed.
But because the new pipe lining will restrict capacity, King County will need to spend three additional months installing a second 24-inch pipe that will run parallel to the newly repaired line. Two pipes will add enough capacity to increase system reliability.
Contractors will begin trenching along the beach in March, starting from the south end of Lincoln Park heading north.
King County and Seattle Parks Department are coordinating to get the work finished as quickly as possible. During construction of the pipeline trench, the beach will be closed to protect public safety. The rest of the park will remain open, and people will still be able to rent facilities.
The county will also be holding meetings with neighborhood groups and the public to answer questions and address concerns.
King County's Wastewater Treatment Division protects public health and water quality by serving 17 cities, 17 local sewer utilities and more than 1.4 million residents in King, Snohomish and Pierce counties. Formerly called Metro, the regional clean-water agency now operated by King County has been preventing water pollution for more than 40 years.
Water Quality Planner
Department of Natural Resources and Parks
Wastewater Treatment Division
201 S. Jackson St. KSC-NR-0505
Seattle, WA 98104-3855
Office: (206) 263-6543 FAX: (206) 684-1278 http://dnr.metrokc.gov/wtd/
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