King County is currently reviewing several options to replace a sewer pipeline in North Mercer Island and Enatai, which conveys sewage from the North Mercer Pump Station across the Island to the Sweyolockyn Pump Station in Bellevue. Project design will begin in 2016, and construction is expected from 2019 to 2022.

Installed in the 1970s, the current sewer pipelines are aging and reaching capacity. During the planning phase, the project team identifies and evaluates locations for a new pipeline and wants to hear from residents.

The existing location is an option because this alignment has proven itself in operations, but in this case, where a pipeline is located in the water, the County is looking for additional options to move it upland.

The County hosted two open houses in September to hear from Islanders. The Council discussed the project on Nov. 16.

The County has five options under consideration. Two are variations of an on-land alignment between the North Mercer Pump Station and the East Channel Bridge, one of which is expected to impose significant impacts to the use of the trail during construction. The other will impact the use of North Mercer Way during construction.

One option is similar to the existing pipeline alignment, which is a combination of onland and in-lake construction. The last two are variations of on-land and in-lake construction, utilizing a trenchless construction technique from the intersection of 78th Ave S.E. and S.E. 24th to the lake. One will cross private property, and will require the County to secure easements for construction.

The Utility Board discussed the project on Oct. 6, noting that early comments received include concern that construction on North Mercer Way would have significant impact to the community, especially in light of the on-going construction activities on I-90, and that construction through Luther Burbank Park would have impact on the park activities and the wetlands.

Several groups weighed in during the public input process. The Friends of Luther Burbank expressed opposition to going through the park and reinstalling the pipe in the water if there are other upland options available. Bicycling groups are encouraging the installation along the Aubrey Davis Park (I-90) path and resurfacing of the path to improve trail conditions.

The Rotary Club is concerned about any impacts to their annual Half Marathon Event and other events in Luther Burbank Park with the North Mercer Way option. Boaters and kayakers have expressed concern about maintaining boating access, not impacting Seafair events and having access to the boat launch.

Generally there is opposition to the North Mercer Way option due to concern about traffic impacts, access to homes and emergency vehicle access, according to the Council’s agenda bill.

Increasing sewer capacity will allow King County to provide reliable wastewater service through the year 2060. In early 2016, the project team will present the recommended option and begin working with neighbors and community during the design phase.

Wastewater from Mercer Island and Bellevue is sent to South Treatment Plant in Renton.

Go to www.kingcounty.gov/environment/wtd/Construction/East/NMIEnatai.aspx for more.