CN 3.9 states: “Where the man-made impermeable area draining to the watercourse (natural or municipal) has decreased or remains unchanged post-development, the peak and volume rate of run-off requirements for the surface water run-off credits will be met by default… In this instance a flood risk assessment must be carried out and any opportunities identified to reduce surface water run-off are implemented.”
Where the flood resilience credits are not being targeted, a flood risk assessment is not required. Instead, a separate study identifying opportunities to reduce surface water run-off may be carried out, and the measures implemented.
Where there is no change in impermeable area, opportunities should be identified to reduce run-off. It is not necessary to carry out a flood risk assessment to fulfill the intent of this criteria.
