The Right-sizing of Green Stormwater Infrastructure project aims to develop standards for GSI modeling and sizing. A prior collaborative grant project led by San Francisco in 2018 developed similar standards for sizing bioretention practices. This “follow-up” project seeks to extend that to other types of GSI, including green roofs, permeable pavement, infiltration trenches and chambers.
The project will compare a wide variety of GI modeling methodologies and sizing approaches evaluated, including static, dynamic, event and continuous modeling. An organized inventory of strategies, equations, and tools to improve GSI designer capacity and accuracy will be developed and best practices will be highlighted for each sizing approach, in order to provide benefit to all agencies, as each works within different policy frameworks and at different levels of technical capacity.
The key milestones and deliverables of the project include:
- Producing an Existing Modeling Methods and Tools (state of the practice) Report – a summary of benchmarking and overview of current modeling and sizing practices and tools, along with comparisons of their accuracy, required input data and outputs, and barriers to use;
- Identifying knowledge gaps in model design and opportunities for model improvement;
- Identify best practice approaches for modeling complex GI systems and phenomena, including but not limited to partial infiltration systems, accounting for ET rates in static versus continuous models;
- Providing recommendations on how existing GI modeling tools and methods could be improved;
- Producing a GSI sizing tool – prospective modeling methods and tools to fill the gaps in GI modeling;
- Establishing best practices for modeling GI treatment trains, approximating GI performance and sizing on a subwatershed scale, and other gaps in existing modeling tools and methods;
- Delivering a workshop, a webinar and three technical memos summarizing all the findings and recommendations.
Over the first few months, the project team achieved several key accomplishments. It contracted with Jacobs Engineering Group and Lotus Water, established a work plan of key milestones and deliverables, and completed the first phase of the projects with the development of the state-of-practice report – a comprehensive inventory benchmarking and comparing various modeling strategies and tools at participating agencies.
Collected for the report were the sizing tools and guidance currently being used by most collaborating agencies, as well as Seattle, a not-collaborating agency, due to the value of the tool they use. Rainfall data sets were also collected so that a relevant tool can be developed for each geographical location. Jacobs Engineering presented an overview of the report at February’s Design Innovations workgroup meeting.
In future months, an additional report, a webinar for Exchange members and the development of a sizing tool will take place.
With questions about the project, please reach out to Matt Wilson at Matt.Wilson@kitchener.ca.
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