Conference Agenda

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Session Overview
Session
Session 02C: Stormwater - Livestream
Time:
Monday, 13/Sept/2021:
3:00pm - 5:15pm

Location: 120AB

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Presentations
3:00pm - 3:45pm

A Scalable Decision-Making Framework For Stormwater Retrofit Investments

Blair Scott1, Robin Kirschbaum2

1King County; 2Robin Kirschbaum Inc.; ,

King County (County), WA, Stormwater Services Section (SWS) has identified the lack of stormwater controls in older developed areas as one of the most significant problems preventing recovery of the County’s streams, lakes, and Puget Sound. With approximately 150 square miles of untreated developed areas and population growth among the largest over the last decade of any county across the United States, the need to strategically plan and begin implementing stormwater management to control stormwater runoff and restore or prevent further degradation of aquatic health is considered urgent by King County and its regional planning partners.

SWS is working collaboratively with Robin Kirschbaum, Inc. (RKI) to develop clear goals and a strategic decision-making framework for identifying, prioritizing, and implementing stormwater management and engineering projects led or influenced by SWS that restore aquatic resources through improved stormwater controls. Building on existing County programs, policies, and initiatives, the project will not only focus on water quality and aquatic health, but on broader principles of critical importance, such as equity and social justice (ESJ) and climate change preparedness.

The decision-making framework will address subbasin prioritization and individual project identification, evaluation, and prioritization organized around the following multi-benefit outcomes:

  • Improve water quality outcomes
  • Increase resilience to climate change impacts
  • Preserve and restore wildlife habitat
  • Implement Environmental and Social Justice
  • Increase community stewardship
  • Accelerate or exceed regulatory requirements using stormwater retrofits

The decision-making framework will serve as a foundational pillar of the County’s 30-year plan for stormwater investments, currently being co-designed and co-implemented by a group of partners from across the region. The stormwater investment plan will rethink the region’s approach to addressing polluted runoff and prioritizing the needs of the residents impacted the most.



3:45pm - 4:30pm

A Greenhouse Evaluation of Stormwater Remediation Of Heavy Metals And PFAS By 10 Native Oregon Plants

Richard Hilliard, Bethany Parker, Jennifer Field, Tyler Radniecki

Oregon State University, United States of America;

Stormwater collects dissolved and particulate phase pollutants from improved surfaces and carries these to receiving water bodies, degrading their quality. Contaminants of particular concern include per- and polyfluoroalkyl substances (PFAS) and heavy metals such as copper and zinc. Infiltration systems of various designs are being implemented widely to provide passive treatment of these waters. Inclusion of plants in these systems provides potential for phytoremediation, prevention of erosion, increased soil porosity, and an aesthetic quality in the built environment.
Plants, along with associate microbes often vary greatly in their provision of degradation and removal of stormwater pollutants. In this study, 10 different native Oregon plants (n=6) including various monocots and dicots were investigated for potential treatment of copper, zinc, and PFASs (spiked-in) in surface runoff collected from a public works utility site in a 10-week greenhouse experiment. Aqueous, soil, and plant samples were analyzed using a combination HPLC-MS/MS and HPLC-QToF for PFAS and ICP-MS for heavy metals. Throughout the experiment, evapotransipration rates were monitored by weighing of the planted units. After the experiment, plant physiological qualities (masses and lengths of roots and shoots) were recorded. Enrichment of plant microbiomes in the rhizosphere and the bulk soil was evaluated by 16s rRNA amplicon sequencing to examine whether microbes are involved in stormwater phytoremediation.

Preliminary data suggest that some plants were much more effective at removing PFAS, particularly the shorter chain compounds. Additionally, some plants showed a net production compared to the control of PFPeS, PFBS, and PFHxS, suggesting the transformation of parent compounds FHxSA and FOSA.



4:30pm - 5:15pm

Emerging Technologies for Stormwater: A CMAC Pilot Project

Josh Van Wie1, Peter Holte2

1Osborn Consulting, Inc.; 2City of Redmond; ,

Emerging technologies for stormwater are playing a crucial role in the Pacific Northwest to help municipalities meet their NPDES permit requirements and watershed management goals. Public agencies and their consultant teams must rely on innovation and collaboration to harness the latest technologies as permit requirements become more stringent and watershed management becomes more critical in urbanized areas.

During 2020-2021, the City of Redmond completed a pilot project to install Continuous Monitoring and Adaptive Control (CMAC) retrofits at two stormwater ponds. The CMAC system uses cloud software to optimize and control pond discharge flow rates through a remotely operated control valve. This technology was selected because of its potential to improve flow durations and protect downstream creek habitat in areas that were developed prior to current regulatory requirements for flow control.

To initiate the pilot project, Redmond identified four stormwater ponds as possible retrofit locations in the Monticello Creek watershed, which was previously selected as a priority watershed for the City’s 2013 Watershed Management Plan. A feasibility study was completed by Redmond’s consultant team, led by Osborn Consulting, to analyze the four ponds using the Western Washington Hydrology Model (WWHM) to assess potential improvements in flow durations at each pond after installing a CMAC retrofit. The modeling proved to be a valuable step in the process as some ponds showed significant potential improvements while the others showed little to no improvement due to site-specific hydraulic configurations or changes in basin hydrology that had occurred since the original design and construction.

Two ponds were selected to move forward with final design in late 2020 and construction of the CMAC retrofit installations in early 2021. The performance of the CMAC system will be monitored to determine its effectiveness and whether this technology has potential for more widespread use in helping the City meet its stormwater management goals.



 
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