TRACK 1, DAY 1
Balancing Level of Service and Flood Risk: Are We Bound to Oversize Municipal Stormwater Infrastructure?
Wednesday, March 26, 2025 | 11:00 a.m. to 11:30 a.m. | Hall A
ABSTRACT
The City of London is located within the Thames River Watershed and the 250-year storm is defined as the regulatory event.
The current hydrologic modelling methodology does not incorporate the minor system (i.e. designed to convey up to 5-year storm event), storage features such as ponds, or depression storage in pervious (forests, open spaces, parks) and impervious areas (i.e.: road sags, parking lots).
The resulting peak flows are predicted to be much higher than the measured peak flows through flow monitoring of the minor system. While peak flow is a driving factor in delineating floodplain boundaries, it also impacts the sizing of municipal infrastructure and the implementation costs borne by municipalities.
In an effort to simulate and compare the relative peak flows, the City modeled the dual drainage network (major and minor systems) in an older, existing, and fully developed neighborhood using PCSWMM.
The model was calibrated using monitored flow data which are much less as compared to the conservative peak flows used for floodplain mapping and municipal infrastructure design in regulated waterways.
In the absence of updated hydrologic/ hydraulic modelling approaches from the province, the current modelling approach poses a challenge for municipalities and may result in oversized municipal infrastructure which can be costly to implement and maintain.
This presentation will highlight the key findings from the dual drainage modelling exercise, lessons learned, municipal infrastructure sizing and varying costs, key parameters of interest and recommendations.
ABOUT THE PRESENTERS
Amna Tariq, City of London
Amna Tariq is a Water Resources Engineer and graduated from the University of Guelph in 2009. Amna recently joined the City of London and is working on various initiatives including floodplain modelling and mapping, Site Plan development reviews and channel improvement and erosion control projects.
Prior to joining the City, Amna was with the Credit Valley Conservation for 10+ years where she held an evolving role including detailed engineering design reviews, hydraulic/hydrologic modelling and performance monitoring of various low impact development projects.
Shawna Chambers, City of London
Shawna Chambers, P.Eng., DPA is the Division Manager of Stormwater Engineering at the City of London. Ms. Chambers holds a bachelor’s degree in Civil Engineering from the University of Waterloo – Water Resources and Environmental Engineering. and a Diploma of Public Administration from Western University.
Her 17-year career at the City has focused on the planning and implementation of municipal stormwater and wastewater projects, including leading multiple Master Plans and construction projects.
As Division Manager, she focuses on delivering practical and effective stormwater infrastructure programs to benefit both the natural environment and the greater community. Ms. Chambers is committed to sustainability, innovation, and challenging the way “it’s always been done.”