Hi Mates,I am looking to determine a percentage of properties resilient to a 100 year storm and percentage of the stormwater system resilient to a 5 year storm. What would be the best approach/method to determine these resiliencies. And what would be needed as inputs to get these values. The aim is to comply with O.Reg. 588/17 in terms of levels of service for Stormwater assets.Regards,Mohammed
Hi, Mohammed. Hopefully this information will assist you in determining your stormwater system resilience. We determined the properties resilient to a 100 year storm by obtaining the 100 year Flood Line shapefile from our local conservation authority which we pulled into our GIS. Using our property and structure GIS layers, we were able to apply buffers of 1.5m around both layers. Any property that fell within those buffers, were flagged as properties that aren't resilient to a 100 year storm, and the rest are resilient to the 100 year storm. Percentage of resilient properties were calculated with this formula:
# of resilient properties = % of resilient propertiesTotal # of properties
We have a Stormwater working group for all the municipalities within our Region, and the following recommendations were documented:
Properties resilient to a 100 year storm: 1. Urban and rural properties where flooding from the Conservation Authority modelled 100 year storm does not encroach within 1.5m of any building on the property, i.e. flooding does not infiltrate into the backfill of a building or 2. Urban properties fronting a municipal Right-of-Way (ROW) with storm infrastructure where the storm infrastructure allows for conveyance of the 100 year storm without directing any runoff beyond the ROW to private property.
Stormwater Management System resilient to a 5 year storm: Any aspect of the Stormwater Management System which has been designed to convey/detain/treat runoff from the 5 year storm event from the year 2019.
I've attached the map I created to include in our AMP for your reference. I hope this helps. Please feel free to contact me if you need more clarification.
Claudia Puchalski, A.Sc.T.Asset Management SupervisorTown of Tillsonburg200 Broadway, Suite 204Tillsonburg, ON N4G 5A7Phone: 519-688-3009 Ext. 4413