North Mercer interceptor emergency
Completed – Spring 2007
To ensure safe and reliable operations for decades to come and minimize impacts to the community, the King County Wastewater Treatment Division replaced 2,300 feet of sewer pipe underneath Southeast 24th Street, 84th Avenue Southeast and Luther Burbank Park on Mercer Island (view map).
The pipe ruptured in one section on 84th Avenue Southeast and in multiple places as a result of the December 14, 2006 windstorm. The damaged pipe is 40 years old and has reached 80 percent of its predicted service life. The pipe material, reinforced fiberglass, is difficult to repair.
Thanks to project neighbors
King County staff wishes to express thanks to the neighbors, city staff, and park and community center users for their patience during this emergency repair project. We know that any construction project can create noise, traffic impacts, dust, and service disruptions, and we appreciate the community's working with us to address these issues.
How the project was completed
Frank Coluccio Construction Company (FCCC) first set up a bypass line to divert flows from the damaged pipe. This bypass pipe was extended into Luther Burbank Park when county inspection staff found damage in the pipe section extending from North Mercer Way into the park.
Next, crews began replacing pipe sections below Southeast 24th Street, 84th Avenue Southeast, and Luther Burbank Park using a method called pipe bursting. Pipe bursting involves expanding the old pipe with a bursting head while pulling the new pipe in place. The bursting head is moved forward into a pull pit.
Pipe bursting minimizes surface disruptions since it requires excavation of pits rather than open trenching of the entire street.
FCCC constructed pits for pipe bursting, and Buno Construction performed the pipe bursting operations. Pipe bursting was completed by February 22, 2007.
On February 8, 2007, pipe bursting operations caused damage to a water line. Plans indicated up to two feet between the water and sewer lines, but the water line was installed with little or no clearance above the sewer line. When the pipe bursting head expanded the old pipe, it made contact with the water line. The contractor repaired the water line and created additional clearance between the two pipes. County staff worked with affected neighbors during the repair operation, when they were without water service.
Restoration in Luther Burbank Park
King County restored the parking and construction areas in Luther Burbank Park. The entrance was repaired, and the overflow parking lot has a new surface and paint.
The contractor removed construction materials from the wetland area in Luther Burbank Park and restore disturbed areas. The county coordinated a community planting event to restore vegetation in the construction area.
Why does King County have a sewer pipe on Mercer Island when the city has sewer service?
The City of Mercer Island's sewer system collects wastewater from homes and businesses. King County receives the city's wastewater for treatment at the county's South Treatment Plant in Renton. The North Mercer Interceptor is part of King County's wastewater conveyance system on Mercer Island. King County serves Mercer Island as part of the county's regional wastewater treatment system, which protects public health and the environment by providing wastewater treatment services for 17 cities and 17 local sewer utilities.
24-hour emergency and odor reporting:
Contact South Treatment Plant at 206-263-1760.
HDPE pipe attached to the bursting head
The bursting head is attached to rods that pull it through the old pipe.
Rods are pulled into a receiving pit, cleaned off, and unscrewed in segments