MIMICO CREEK HYDROLOGY UPDATE - PROJECT DESCRIPTION

Civica was retained by the TRCA to update the hydrology model for Mimico Creek, completed in PCSWMM. The Mimico Creek conveys runoff from Sandalwood Parkway (north Bovaird Drive) in Brampton between Dixie and Torbram Road south through the City of Brampton, the City of Mississauga and the City of Toronto. The purpose of this model is twofold, peak flows generated by the larger storm (Hurricane Hazel, 100 years and 350 years) events will be used in the future for the delineation of floodlines. Peak flows generated for smaller (2 through 100 years) events will be used in the future to confirm the appropriateness of the current SWM criteria. As such, the model calibration and validation were analyzed to using a range of different storm events so that the model can be used for both large and small storm modelling. Conclusions from this project are as follows:

• The 100-year 12-hour AES storm was found to be the major type of storm that will cause flooding on an urban watershed such as the Mimico Creek Watershed.
• The PCSWMM model update associated with this report should be utilized to estimate peak flows for the 2 to 350-year and the Regional Storm event for the Mimico Creek Watershed.
• The hydrologic model should be further adjusted as required when rainfall and streamflow data becomes available for larger events than those events used for the calibration and validation process as part of this study.