Seismic vulnerability study

In 1999, the King County Council directed and authorized a seismic vulnerability study to evaluate all the county's major underwater conveyance pipelines. A comprehensive approach was developed to assess the vulnerability of these pipelines to earthquake damage and to recommend short- and long-term protective action if warranted. The study, which began in May 2000, assessed pipes under Lake Washington, Lake Sammamish, the Ship Canal, sloughs, rivers, and creeks. Several reports were published:

• The first report, completed in April 2002, assessed the seismic vulnerability of the Kenmore Interceptor and identified a range of working alternatives to strengthen certain pipeline joints based on various costs and risks to public health.
• The second report, completed in August 2002, assessed the seismic vulnerability of six other submerged lake lines and three Ship Canal siphons.
• The third report, completed in late 2003, evaluated 30 additional pipes in submerged or liquefiable soils.
• The summary report was prepared to assist DNRP management in determining how to proceed with possible retrofits or actions in conjunction with planned asset management programs and projects.

For security reasons, these reports are not available online.
Please contact us if you wish to obtain a copy.