Spokane Valley Eastern Washington Effectiveness Study
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Let it Rain

Last spring, I had the honor of working with 18 cities and 6 counties in eastern Washington who are regulated by the Phase II National Pollutant Discharge Elimination System (NPDES) Municipal stormwater permit. The project focused on assisting the jurisdictions (permittees) in evaluating the effectiveness of their permit-required stormwater management program activities and best management practices (BMPs). This included leading a team of applied researchers in developing 13 experimental designs (proposals) which will investigate whether the permittees’ stormwater management BMPs are functioning as they are intended to.

The studies focused on all types of BMPs, including structural (such as permeable pavement and bioretention), operational and maintenance practices (such as street sweeping and catch basin cleaning), and education and outreach programs. Adhering to this permit shifts the permittees’ requirements from the presumptive approach (in which BMPs such as swales are presumed to provide stormwater management functions when designed according to stormwater manuals) to a demonstrative approach (in which permittees are required to demonstrate their BMPs provide this function).

Our biggest challenge was to develop experimental designs that would not only achieve permit requirements but also provide the permittees with results that could be used to enhance their stormwater programs. In addition to goals for evaluating effectiveness, many of the studies included goals for developing new BMPs and justifying modifications to their Phase II NPDES permit. One reason for the additional goals is that eastern Washington is located in a semi-arid region which is vastly different than the marine climate in western Washington where most of the research has been conducted to develop structural BMPs. As such, the effectiveness studies provide the permittees with an opportunity to expand their toolbox of BMPs to include options that are practical for their unique climatic conditions.

Like all projects that HDR’s Water Institute takes on, my research team’s approach involved working collaboratively — which was a key to our success. The team included researchers from HDR, Drummond Carpenter, D&H Technology Solutions and Cascade Water Resources who worked together with the permittees and regulators throughout the development of the studies. We first developed a conceptual experimental design with the permittees for each study then requested the regulators’ feedback on the conceptual design before developing the proposal. In addition, the team also created conference style posters for each study which were displayed at the 2017 Washington State Municipal Stormwater conference. This provided an additional opportunity to collect feedback from other stormwater researchers and practitioners before finalizing the experimental designs.

The next phase of the Eastern Washington Effectiveness Studies is to conduct the studies, and we’ve already started! I’m thrilled to continue leading the research team and working with some of the permittees on their studies.

One of these projects includes developing a new sand filter sidewalk vault BMP that is small enough to be installed in an oversized catch basin. This will be located within, or in the place of, a traditional storm drain network and provide runoff treatment of total suspended solids (TSS) to the level required in the permit.

Another project focuses on evaluating the effectiveness of street sweeping compared to catch basin cleaning. A goal of this study is to demonstrate that more frequent street sweeping can result in the need for less frequent catch basin cleaning, subsequently justifying modification to the respective Operations and Maintenance section of the permit.

When it comes to applied research, there is nothing better than working with a team to physically prove a concept. On behalf of my team, “Let it rain.”