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Stormwater Treatment & Infiltration Where You Can’t

Presenters – Duane Studer, City of SpokanePresenters – Duane Studer, City of Spokane

The City of Spokane designed and constructed an innovative stormwater treatment facility to reduce discharges of runoff pollution to the impaired Spokane River from a basin where PCBs and heavy metals are ubiquitous. The presence of legacy contaminants in stormwater and subsurface soils required a solution beyond typical bioswale designs. Runoff impacted by 303d listed contaminants is detained in an 80,000-gallon subsurface concrete storage tank before being metered into a lined bioinfiltration swale constructed with an underdrain to convey the effluent offsite for infiltration. The project was achieved with Ecology funding and private partnerships, and it offered several challenges and learning opportunities. By being open to innovative treatment system designs and cooperative partnerships, a creative solution was implemented on a challenging footprint to reduce discharges of untreated runoff to a 303d listed waterway.

City of Spokane: Cochran Basin Stormwater Mitigation

Presenters – Mark Papich, City of Spokane

Stormwater runoff from the Cochran Basin in north Spokane is currently conveyed to a single outfall on the Spokane River, which can see discharges of up to 200 million gallons annually. This basin is the City of Spokane’s largest MS4 basin, covering approximately 5,200 acres. Multiple BMPs have been implemented and will use green stormwater infrastructure to manage all stormwater runoff generated in the basin from rain events up to the 6-month design storm. The project consists of an innovative control vault and pump station that separates and conveys a dedicated flow rate of run-off calculated to each of several downstream multi-use stormwater treatment facilities that act as recreation areas when not actively managing stormwater.

A Modeling Approach to Cost-effective Stormwater Planning

Presenters – Stephanie Truitt & Carly Greyell, King County

Stormwater utilities often face difficult decisions in siting new projects and choosing when and where to update aging infrastructure. King County’s Water Quality Benefits Evaluation (WQBE) Toolkit provides a suite of modeling tools that allow us to make data-driven decisions on how we invest in stormwater infrastructure. The WQBE Toolkit uses the SUSTAIN model to evaluate cost-effective stormwater solutions for three programs: GSI Incentives, Roadway Treatment, and Regional Facilities. A user can select a cost-based goal or a pollutant reduction goal. After a goal is chosen, the user can then view the cost-effectiveness curve to see which stormwater BMPs are needed to meet that target. Information from SUSTAIN can support goal-setting and regional collaboration as a part of a larger decision-making structure. This presentation will demonstrate how the WQBE Toolkit can contribute to cleaner, healthier waters in King County, and provide a framework for modeling in other locations.

Lincoln Street Stormwater Projects: Creative Solutionism

Presenters – Trey George, City of Spokane

The presentation will provide details for each project individually with a focus on the unique aspects of the project to include aesthetic considerations and design solutions unique to the location (e.g. right of way vegetation for homeowners to maintain, an unlikely discovery of a beneficial infiltration location, and use of some unutilized space at the base of an interstate on-ramp). The project discussions will culminate into an overview of the arterial stormwater system as a whole that identifies the larger scale benefits such as aquifer recharge, minimizing pollutant transport, freeing up wastewater treatment capacity, cost savings, and beautification, among others. Challenges that required outreach will be presented with lessons learned, specifically incorporating homeowner buy-in into vegetation design for a project that replaced turf grass with bioretention cells the homeowners were to maintain per city ordinance.

Wenatchee 9th Street Stormwater Retrofit: Meeting Community Needs Through Stormwater Planning

Presenters – Josh Van Wie, Osborn, and Darci Mattioda, City of Wenatchee

The 9th Street Basin Stormwater Retrofit Project provides an example for public agencies needing to efficiently address multiple needs. The City is utilizing an Ecology SFAP Grant to add stormwater retrofits in an area lacking water quality treatment and conveyance for storm events. The retrofits will improve water quality in the Columbia River and Chelan County’s No. 2 Canyon Drain, an open channel, by removing untreated runoff that currently discharges to the Canyon Drain from the surrounding streets and Wenatchee Valley Community College campus. Constructing new water quality treatment facilities and conveying treated runoff through the City’s storm drain system to the river will meet the goals of the SWMMEW, the municipal stormwater permit, and the city’s comprehensive plans for stormwater management.

Building Toward Collective Regional Action on Stormwater

Presenters – John Brosnan, King County

King County and its partners have been supporting a regional summit series, calling for greater watershed-scale coordination on stormwater management across Puget Sound. Beginning with an event in April 2021, hundreds of regional stormwater practitioners gathered at the first Aligning Across Watersheds: A Stormwater Summit. Local jurisdictions can each meet their NPDES regulatory requirements, but that does not change the fact polluted stormwater remains the largest source of untreated pollution that reaches Puget Sound every year. What is the full range of benefits the region could realize with enhanced watershed-scale co-planning and implementation strategies? Join us to learn more.

Addressing Escalating Project Costs Panel Discussion

Presenters – Kaela Mansfield, EvergreenH2O, Jon Morrow, City of Ellensburg, Mark Papich, City of Spokane, Tony Bush & Keith Dusler, WSDOT, Adam Benton, City of Marysville, Shilo Sprouse & Jessica Schwing, Dept. of Ecology

Over the last few years, inflation has significantly impacted budgets and delivery of both stormwater design and construction projects. This panel presentation is intended to focus on managing recent inflation issues and hard-to-predict future cost conditions. The panel will include representatives from municipalities on both sides of Washington State, as well as Ecology, for a discussion about their experiences and lessons learned addressing rising costs related to engineering projects. Topics will include planning, designing, and constructing projects; labor and material costs; and proactive approaches to mitigate cost escalation including on grant-funded projects. The open format session will be guided, with the opportunity for the audience to ask questions and learn about best practices for managing escalating costs on their projects from planning through construction.

Piloting Innovative Stormwater Treatment on Waterfront Properties

Presenters – Jane Dewell, Port of Seattle

This presentation features low-tech stormwater treatment examples with monitoring data that demonstrates the effectiveness of oyster shells, bioretention in a box, and commercial products that fit small footprints (e.g., Hula Bug? and Retain Drain). We make use of systems with straightforward operation and maintenance (O&M) protocols that improve stormwater quality for properties that discharge directly into urban rivers and bays. The SWU will share monitoring information, O&M wisdom, and educational materials intended to encourage other commercial and industrial operations to add low-tech stormwater treatment to supplement BMPs or as pre-treatment to more sophisticated treatment technologies.

The Park Place and Post Media Story

Presenters – Chris Webb & Dylan Ahearn, Herrera

This presentation describes the story of the development of the POST media and the Park Place Stormwater Facility in Bellingham. The project began with an R&D phase (2018) which entailed testing media components to create a new high-rate non-proprietary stormwater treatment media targeting phosphorus removal. Then a pilot scale filter (2019-2021) was built and monitored and achieved a GULD for phosphorus in 2021. Then a full-scale facility was designed and built around an active dosing system with construction beginning in June 2021 and the project being completed in 2022. This project resulted in a high-performance regional stormwater facility to meet TMDL goals that also 1) created a new open-source stormwater treatment tool for the region, 2) implemented the tool for the first time, 3) used a PLC-based active dosing system for the first time on a stormwater project in the region, and 4) met the City’s cost-effectiveness threshold.

Stormwater Parks

Presenters – Jenny Gaus, City of Kirkland, Michelle Perdue, Kitsap County

Stormwater parks are facilities that provide both stormwater treatment and recreation and can help with many challenges that cities and counties face, such as equity, health, and degraded water quality. They can provide cost-effective regional stormwater retrofits in impaired watersheds. Stormwater parks that have been built to date vary greatly in form, function, and size, indicating they can work well on a variety of sites. The objectives of the session are to show different types of stormwater parks and share guidance on planning stormwater parks, as well as lessons learned from planning, constructing, and maintaining them.