Civil Engineering · Engineering Glossary
A storm drain system is the network of inlets, pipes, and channels that collects surface runoff from streets, parking lots, and developed areas and conveys it to detention facilities, retention basins, or natural water bodies. Storm drain design ensures adequate capacity for design storm events while managing water quality.
Storm drain systems include curb inlets, area drains, catch basins, underground pipes (typically reinforced concrete pipe or HDPE), manholes, and the outlet structure at the point of discharge. The civil engineer calculates the peak runoff from each drainage area using the Rational Method or continuous simulation models, then sizes the pipes to convey the design flow within allowable depth and velocity limits. Minimum slopes prevent sediment deposition; maximum velocities prevent pipe erosion. Outfalls to natural waterways require evaluation for erosion protection and may require a floodplain permit. Storm drain construction typically falls under the civil permit, and systems discharging to public right-of-way require review and approval by the local public works department.
Apex Grid Engineering maintains this glossary as a resource for architects, contractors, developers, and property owners who encounter unfamiliar engineering terminology on their projects.
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