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Stormwater management trade-offs for Portland, Seattle and Vancouver, BC

University of British Columbia

The separation of stormwater from the sewage waste stream has been implemented in many cities to minimize combined sewer overflows (CSOs) during periods of heavy rain. In the absence of treatment, discharges from separated sewer/stormwater outfalls are also very damaging to aquatic environments as they typically carry numerous nonpoint source pollutants and alter the delicate geomorphology of natural watercourses. A new strategy has emerged during the past few decades that focuses on absorbing, infiltrating and detaining stormwater to reduce peak flows and filter out nonpoint source pollution, thereby addressing CSOs, stormwater runoff pollution and flooding at the same time. An increasing number of cities in the United States and Canada have devised comprehensive plans to incorporate these methods into their overall wastewater management strategies. In an effort to eliminate CSOs and build resilience against flooding the City of Vancouver has committed over $1 billion to separate all of its remaining combined sewer/stormwater infrastructure by 2050. In contrast, Seattle and Portland (Oregon), two cities with similar rainfall patterns and levels of urbanization are following strategies that utilize a combination of targeted conventional stormwater infrastructure upgrades and GI to minimize CSOs, stormwater runoff pollution and flooding. As the City of Vancouver moves forward with its city-wide Integrated Stormwater Management Plan, this thesis contends that its sewer separation project should be revised to also include a comprehensive network of GI. The primary investigatory goal of this thesis is to identify and analyze the social, institutional, economic and technical barriers encountered by Portland and Seattle to the implementation of GI and the key factors that enabled its implementation. This is accomplished through interviews conducted with key staff members from Portland’s Bureau of Environmental Services (BES) and Seattle Public Utilities (SPU), supported by a review of recent literature. It was found that Portland and Seattle overcame a variety of social, institutional, economic and technical barriers through the use of cost effective pilot projects, extensive public consultation, slowly changing the internal culture towards GI within municipal departments, offering financial incentives and through increasing the profile of their projects through awards and competitions.

Text

2014-10-23

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/50855

Planning

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/