North Mercer Interceptor emergency project

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 is replacing 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.

We're almost done! Sewer repair project coming to a close

As winter winds down, King County is wrapping up the emergency project to replace sewer pipe on North Mercer Island. Since December 2006, Frank Coluccio Construction Company (FCCC) and Buno Construction have been working to replace sewer pipe running from 81st Avenue Southeast on Southeast 24th street to a connection with the lake line in Luther Burbank Park. 84th Avenue Southeast, closed since Dec., will reopen for general traffic once work is completed.

Project Update

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 24 th Street , 84 th Avenue Southeast , and Luther Burbank Park using a method called pipe bursting (link). 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.

On February 8, 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.

What's next?

Neighbors will see Puget Sound Energy crews working on Southeast 24 th Street and 84 th Avenue Southeast between April 15 and May 15. PSE will perform service upgrades that were put on hold when Southeast 24 th Street was repaved. Once PSE crews complete work, both 24 th Street and 84 th Avenue Southeast will be resurfaced between May 15 and June 1.

Restoration in Luther Burbank Park

King County will restore the parking and construction areas in Luther Burbank Park. The entrance will be repaired, and the overflow parking lot will have a new surface and paint.

The contractor will remove construction materials from the wetland area in Luther Burbank Park and restore disturbed areas. This fall, the county will coordinate a community planting event to restore vegetation in the construction area. Fall is the best time for this since it will give the new plants a chance to grow healthy roots over the rainy winter season.

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.

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.

Construction to cause traffic impacts

During construction, 84th Avenue Southeast between Southeast 24th and Southeast 26th streets will remain closed except for local access. The road closure will also affect Metro bus routes in that area, which will be rerouted around the closure. Check Metro Online at http://transit.metrokc.gov for details.

People should also expect traffic detours and delays on Southeast 24th and 26th Streets and North Mercer Way until end of March.

Luther Burbank Park is open

Trail closures along 84th Avenue Southeast limit public access to this area. The parking lot on 84th Avenue Southeast is closed to accommodate the contractor's equipment and materials, and to reduce impacts to nearby streets. People can still access the park and beach from the Luther Burbank Building parking lot area.

Bicyclists, pedestrians should remain watchful and exercise caution around work areas

Because this area is such a popular bicycle commuter route, bicyclists should watch for flaggers and equipment, reduce speeds through the area, and obey traffic signs. Though crews will work to control construction debris, bicyclists and pedestrians in the area are being asked to use caution and be watchful at all times.

For more information

Contact Monica Van Der Vieren by phone at 206- 263-7301 or e-mail at monica.vandervieren@kingcounty.gov for more information and answers to your questions and concerns.