Modeling LIDs using SWMM5 and MIDS Credit Calculator: Credit Valley Conservation’s Elm Drive case study

Saini Sakshi and Amanjot Singh


Low impact development (LID) is an innovative stormwater management (SWM) practice that consists of green infrastructure, source controls, and conveyance controls. LIDs mimic the natural hydrology of a site by increasing pervious area that allows filtration and infiltration of runoff before draining to a pond, river, or creek. MOECC’s Interpretation Bulletin on Expectations re: Stormwater Management February 2015, clarified the ministry’s policy, emphasizing the need to control precipitation where it falls by implementing LID practices for all forms of development. The Credit Valley conservation (CVC) and Toronto and Region conservation (TRCA) authorities also endorse the implementation of LID through their SWM Criteria documents and LID Stormwater Planning and Design guide. Pertinent to this is the performance evaluation of these practices. LID practices need to be monitored and modeled to evaluate their performance for flow and water quality targets. Taking a step towards this direction, we used three models: (i) the MIDS Credit Calculator developed by EOR for the Minnesota Pollution Control Agency, (ii) the EPA National Stormwater Calculator, and (iii) EPA-SWMM from the US EPA, to model an LID site, Elm Drive, currently being monitored by CVC in Mississauga, Ontario. Results from the models were compared to monitored results from the site to evaluate the accuracy of the models in simulating LID performance. The paper presents the site design details, model setup, including barriers met during model setup, and a review of the volume reduction and water quality results, and how these compared with monitored data.

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