January 22, 2013

ACEC Best in State: Gold award
Originality/innovation

Landau Associates

Project: North Boeing Field short-term and long-term treatment systems

Client: The Boeing Co.

Photo courtesy of Landau Associates [enlarge]

Landau Associates used chitosan-enhanced sand filtration to remove PCBs from stormwater runoff at North Boeing Field.

Boeing has been working for some time with local communities, businesses and government agencies to clean up the Lower Duwamish Waterway adjacent to their North Boeing Field. Named a Superfund cleanup site by the U.S. Environmental Protection Agency, this area was awash in stormwater runoff polluted with polychlorinated biphenyls, or PCBs, that needed to be eliminated prior to sediment cleanup.

Landau Associates worked as Boeing’s environmental consultant to help characterize PCB sources, implement source control measures and design both short- and long-term stormwater treatment systems that use chitosan-enhanced sand filtration.

This project represents the first and largest known use of chitosan-enhanced sand filtration at an industrial facility to remove PCBs from stormwater. Landau Associates chose the technology over the traditionally used granulated activated carbon as it was less costly and more effective at this site.

In 2010, Landau designed and installed a 500-gallon-per-minute interim stormwater treatment system at North Boeing Field that treated approximately 35 million gallons of stormwater in two months. In 2011 the long-term stormwater-treatment system was installed to treat stormwater in the 300-acre drainage basin that includes North Boeing Field and King County International Airport. This permanent system can treat 1,500 gallons per minute, and in its first 11 months of operation it treated 176 million gallons of stormwater.

In addition, Landau designed and implemented a sophisticated monitoring system that includes a Doppler velocity sensor in the existing King County lift station stormwater discharge structure that will quantify total stormwater discharges, determine the percent of stormwater treated on an ongoing basis and allow collection of stormwater samples from the site.

The Lower Duwamish Waterway in Seattle is a gateway to salmon runs, industrial manufacturing, transportation and local recreation. Landau’s environmental engineering solutions to Boeing’s stormwater treatment show that this critical cleanup process can be done effectively and efficiently in industrial zones so that costly sediment cleanup can proceed without fear of sediment recontamination in the future.

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