SG3 and SDOT

Utility Optimization – Lessons from the Seattle Seawall

In April 2017, Scott Goss and Lorelei Williams, Director of Capital Projects and Roadway Structures for the City of Seattle Department of Transportation (SDOT), presented at APWA’s Spring Conference. “Utility Optimization: Lessons from the Seattle Seawall”, shared best practices from the ongoing Waterfront Seattle Seawall project, pulling from experience mitigating the unexpected and capitalizing upon opportunities to elevate results.

Attendees expressed a strong interest in learning how to generate more value from major infrastructure asset improvements, and asked detailed questions. Among the most popular were the following:

Q. What recommendations do SG3 and SDOT have for designing a project like this relative to utilities?

A. Utilize more subsurface utility exploration and mapping. Don't trust utility locate marks.

Q. How can contractors protect vaults from jet grout?

A. Start with low pressure half circles instead of full circle high pressure columns. Also use void filling at low pressure.

Q. On the Seawall project, how did cost of soil freezing compare to dewatering?

A. Although soil freezing was expensive, dewatering was not feasible due to quantities, expense, contamination and severe drawdown effect on viaduct columns. We spent over $250,000 in one week just dewatering for one vault before switching to soil freezing.

Want to check out our presentation? Visit https://youtu.be/XAB9FsczzuA