Development of a Low Impact Development and Urban Water Balance Modeling Tool

The Toronto and Region Conservation Authority (TRCA), Lake Simcoe Region Conservation Authority (LSRCA), and Credit Valley Conservation Authority (CVC), “the GTA CAs,” have worked collaboratively to identify preferred low impact development (LID) stormwater management (SWM) models suitable for meeting typical design criteria. The GTA CAs research and experimentation efforts with various LID SWM case studies will inform the audience of model criteria and rationale that supports the selection of preferred open-source and/or commercial license LID modeling tool(s) which effectively demonstrate design targets have been met. The GTA CAs commissioned Golder Associates Ltd. to provide programming support and water resources expertise to support the development of the LID Treatment Train Tool (LID TTT) for Ontario, presently in a working beta version for review and experimentation before a planned hard launch in late March, 2017. The primary intention of the LID TTT is to support more consideration and realization of LID opportunities for a proposed site plan, throughout the design process undertaken by planners, SWM designers, and other decision makers for all types of site development or retrofit projects. The LID TTT will process computational results from EPA-SWMM to provide an assessment of stormwater runoff volume and associated target depths, along with total suspended solids (TSS) and total phosphorus (TP) reductions for both annual and event based scenarios, throughout the design process. A preliminary water budget assessment for pre and post conditions is also provided in the beta version of the LID TTT.