Seattle Public Utilities

Seismic Planning

  • 30-inch water maiNew earthquake-resistant 30-inch watermain on S Spokane St.
  • Cylinder on the base of Myrtle Tank Cylinder on the base of Myrtle Tank was installed to reduce earthquake vibrations.

Timeline

1990

Cygna Energy Services completed a comprehensive seismic vulnerability assessment of the Seattle Water Department’s facilities.

1990 – Today

We have been addressing the issues identified in the Cygna assessment, as well as planning for and incorporating modern seismic standards into new projects mandated by federal and state regulations.

Balancing priorities between seismic upgrades, regulatory-driven projects, and other capital needs while maintaining affordable rates has been an important element of the utility’s thinking—especially as we kept abreast of the evolving understanding of seismic risk in the Puget Sound region.

1997

The Seattle Water Department merged with other city departments to form SPU.

2014

SPU hired a recognized seismic expert to oversee our seismic planning.

2015 – 2018

SPU embarked on a new water system vulnerability study.

The study evaluated how our water system might respond to two earthquake scenarios:

  • A magnitude 9.0 Cascadia subduction earthquake off the Washington coast
  • A magnitude 7.0 Seattle Fault earthquake centered in Seattle