Hazard Mitigation Case Study: The Bellingham Waterfront

 

History of the waterfront: 

    The Bellingham waterfront is located along Bellingham Bay in close proximity to downtown Bellingham. The location is the site of the old San Juan Pulp company, which was constructed in 1926 on five acres of tide flats that had been filled in with sediments from the Nooksack River and Squalicum Creek. In 1963, the San Juan Pulp Company merged with GP, and constructed a chlorine production plant that was used to bleach the wood pulp. Between 1963 until 1978 the chlorine production plant was discharging large quantities of mercury into Bellingham Bay. Finally in 1978, in accordance with the Clean Water Act, GP constructed an Aerated Stabilization Basin in which to deposit mercury. In 2000 GP closed, and the waterfront was purchased by the Port of Bellingham. All of the original GP facilities remain, and the Port of Bellingham now faces the task of cleaning up the site, and the possibility of redevelopment.

Bellingham Waterfront & Natural Hazards: 

    The Bellingham waterfront is an area of heightened risk for Earthquake hazards and associated impacts. Potential sources of Earthquakes in the area include the Cascade Subduction Zone, numerous faults located throughout the Puget Sound area, the MacCaulay Creek Thrust Fault located near Deming, WA, and two recently discovered faults located in Whatcom County, the Kendall Fault, and Boulder Creek Fault.

Potential Earthquake Impacts: 

Two potential impacts of Earthquakes on the Bellingham Waterfront include liquefaction and tsunami inundation.

·       Liquefaction: 

       Liquefaction occurs when ground shaking resulting from an earthquake causes unconsolidated, saturated sediment to lose its shear strength, thus causing it to behave like a liquid or quicksand. Because the Bellingham Waterfront is comprised entirely of fill, this is an area of high susceptibility to liquefaction in the event of an earthquake. Liquefaction has the potential to be very damaging to the built environment and human life due to the possibility of catastrophic failure of the built environment. See the subpage Liquefaction Mitigation Techniques.


·       Tsunami Inundation: 

    The second impact on the Bellingham Waterfront from an associated Earthquake is the potential for Tsunami inundation. An earthquake along the Cascade Subduction Zone would displace large amounts of water, in turn causing a Tsunami to propagate outward in all directions. In the case of a CSZ earthquake, Bellingham Bay would be inundated by the first crest of the Tsunami approximately two and a half hours after the occurrence of the earthquake. Localized tsunamis may also result from earthquake induced landslides sliding into Bellingham Bay or surrounding areas, or from subaqueous landslides resulting from an earthquake. In the event of a landslide induced tsunami, the time before inundation occurs is much shorter. Tsunami inundation maps from the Washington State Department of Natural Resources indicate that the Bellingham waterfront would likely be inundated with 0 to 0.5 meters of water (up to 1.64 ft), around knee height. However, the height of inundation also depends on the tides, so the precise inundation levels are still somewhat ambiguous.  The velocity of the Tsunami in the Bellingham waterfront area would be between 0 to 1.5 meters/sec. (about 3 mph) and in some localized areas of the waterfront the velocity could be between 1.5 to 5 meters/sec (a moderate running pace). Additionally, tsunami inundation could result in erosion of the waterfront, thus making any facilities near the edge of the waterfront susceptible to having their foundations undercut, potentially causing a failure of the building. Although tsunami inundation of the Bellingham waterfront does not pose a very serious threat to human lives, due to the fact that inundation is restricted to the direct shoreline, the threat to the built environment is substantial and should not be taken lightly. The return period for CSZ earthquakes is around 550 years and the most recent CSZ earthquake resulting in a tsunami was in 1700 as evidenced by historical records and tsunami deposits. See the subpage Tsunami Inundation Mitigation Techniques.


Links to Hazard maps/resources:

·       http://geology.wwu.edu/rjmitch/whatcom_liq.pdf  (Liquefaction susceptibility map of Bellingham)

·       http://www.dnr.wa.gov/Publications/ger_ofr2004-15_tsunami_hazard_bellingham.pdf  (Tsunami Inundation map of Bellingham)


Scott Seren