Madison Valley NW Diversion & Washington Park Storm Water

Project Summary

The project included construction of a new storm water conveyance and storage system in the Madison Valley basin in Washington Park.  Designed to greatly reduce the potential for flooding, the new storage system in Washington Park holds approximately 1.3 million gallons of storm water and will be built partially underground.

The major components of this project included a 100-foot diameter concrete storm water storage tank and 2,500 lineal feet of 60-inch steel casing installed with open shield bore and jack tunneling methods. Additional storm water storage sits above ground in a bermed landscaped area and will only be utilized during extreme storms.

This was a high-profile project in a residential and commercial neighborhood that is notorious for flooding.



Seattle, WA


City of Seattle

Contract Amount

$17.5 Million


Seattle Public Utilities


July 2010 - December 2012

Project Highlights

The project was put on hold in early 2012 due to weather conditions and pending design changes by the client, who issued a $1.8 Million change order to the original contract and extending the project completion date to September 2012.