Midway Sewer District Submarine Outfall

Project overview

Vanir’s constructability review, bid marketing campaign, on-site construction management and inspection services led to the successful delivery of this complicated project. The marine outfall project included:

  • 2,100 linear feet (LF) of owner-furnished, 48-inch concrete cylinder pipe and 250 LF of bored and jacked steel casing
  • Sheet pile shoring, cathodic protection of the outfall pipeline and protection and restoration of the beach and park

Overcoming Challenges

Marine projects present unusual challenges due to constraints from permitting agencies, local jurisdictions and natural conditions. To help manage this, Vanir created a comprehensive table that identified all constraints and requirements grouped into specific areas of work. This was distributed and discussed with the project team prior to starting construction.

In-water work was scheduled within the “fish window” timeframe issued by the Washington State Department of Fish and Wildlife. Beach work was scheduled around tides and the beach had to be protected from damage. Eelgrass had to be harvested prior to sheet pile installation in the eelgrass zone, maintained during construction and replanted after construction. The upland and intertidal work took place in the summer on a popular beach park near a marina.

The project team had to find the proper balance of safety and access to meet the needs of the public. Community relations was an important part of Vanir’s on-site inspector’s role.

Des Moines, Washington
Midway Sewer District



General Construction Company

Construction Cost
$4.3 Million
Start Date
Completion Date