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9611 SE 36th Street
Mercer Island, WA 98040
Phone: 206.275.7600
Fax: 206.276.7663
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Frequently Asked Questions

What part of the lakeline will be affected?
The City will replace the lakeline on the north and northwest shoreline of the Island and includes two segments: Reach 3 (Proctor Landing - SE 32nd Street & 60th Avenue SE - to Roanoke Way) and Reach 4 (Lincoln Landing - SE 20th Place & 76th Ave SE - to the 8000 block of SE 20th Place).  The section of pipe is 9,000 linear feet.  Click here to view a map of the project area.

How does the Islandís sewer system work?
A sanitary sewer pipe, partially buried in Lake Washington five to ten feet offshore, surrounds Mercer Island. Sewage is transported by gravity from the upland elevations down to the lakeline. Once in the lakeline, sewage is conveyed around the Island by City-owned pump stations to two King County pump stations and from there, across Lake Washington to the regional sewage treatment plant in Renton.

Why does this section of the lakeline need replacement?
The pipe needs to be replaced because of four factors:

  • Deterioration: much of the pipe in the affected area was constructed of asbestos cement pipe, which, after 50 years, is crumbling.
  • Adverse environmental impacts: as the pipe continues to deteriorate, breaks and leaks will occur with increasing frequency, resulting in contamination to Lake Washington.
  • Inadequate capacity: the current 10- and 12-inch pipes cannot adequately handle sewage and stormwater inflows that occur during severe storms.
  • Costly maintenance: the current line has no clean-out access for inspections and cannot be adequately maintained.
How much will construction cost?
Cost is expected to be upwards of $15 million.

Who will pay for this? Will there be additional assessments to homeowners?
The City of Mercer Island has been setting aside funds from existing sewer rates for several years to help pay for this project.  The City was successful in securing a $1.0 million low-interest Public Works Trust Fund loan in 2003 for pre-construction activities and was successful in securing a $7.0 million low-interest loan in 2005 for construction from the Washington State Public Works Board.  The City continues to explore other funding opportunities such as grants or low-interest loans.

What is the timing for this project?
Pending permit approval, the City hopes to begin construction during the summer of 2007.  Because salmon migration limits the period of time when construction could occur in the lake, the project will likely extend over two summers, with in-water work occurring between mid-July through September.

How many homes will be affected?
About 100 homes will be directly impacted by the project.

How will homeowners be affected?
The City is committed to minimizing the impact to affected homeowners and to the community. Several replacement scenarios are being evaluated, and all have varying impacts. The City issued the Final Environmental Impact Statement (FEIS) in March 2005.  the FEIS evaluated four alternatives.  Alternative 3b: In-lake Alignment (dual pipeline) was identified as the City's preferred alternative.

What will happen next?
The City of Mercer Island is committed to keeping residents informed. Small neighborhood group meetings will be held and a larger community meeting will be hosted this fall. We will notify you by mail when important decisions have been made. In the meantime, additional information will be posted to the City's web site.


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