On-site stormwater storage is commonly required when post-development runoff must be detained so discharge stays within an accepted rate or downstream capacity. The need and volume come from project-specific criteria and calculations, not a universal site-size rule.
Why storage is used
Roofs and pavement can make runoff reach the outlet faster. A control device limits the release, while temporary storage holds the difference between inflow and outflow. Storage can also support treatment-train or water-balance objectives, depending on the design.
Common locations include roofs, parking-lot ponding areas, landscaped depressions, oversized pipes, tanks and ponds. LID features may contribute to the strategy where soils, groundwater, municipal acceptance and maintenance support their use.
Space and operations matter
Storage is not only a calculation. The design must show high-water levels, depth, freeboard, overflow, structural or surface constraints and safe recovery after a storm. Surface ponding cannot obstruct required access or create unacceptable risk at entrances and property lines.
A park can sometimes incorporate a stormwater facility or controlled storage in open space, but public function remains important. Fields, dog off-leash areas and paths need suitable drainage and recovery, while accessible routes and play areas require careful protection. Maintenance responsibility should be understood before the facility is accepted.
Bous Engineering develops project-specific stormwater management reports and storage concepts. Related references cover LID practices and the necessary major storm flow route.
Key takeaway
Storage is required when the accepted outlet condition cannot receive uncontrolled runoff. Select the location and control method with grading, public use, maintenance and emergency overflow in mind.
Bous Engineering supports servicing, stormwater, grading and municipal approval assignments across Eastern Ontario.