Also known as runoff or rainwater, collects pollutants such as oil, fertilizer, and pesticides as it flows over land
Proper management of storm water is crucial to prevent contamination of water sources and mitigate potential damage to buildings
Recurrence intervals
The statistical estimation of the probability of precipitation events
Recurrence intervals
1 in 50 chance of 5.0 in of rain in a 24-hr period
Rainfall total of 5.0 in during a consecutive 24-hr period has a 50-year recurrence interval
Storm water systems are typically designed to handle storm water from a specific precipitation event, typically based on a recurrence interval of 100 or 500 years
Importance of proper stormwater management
Environmental protection
Infrastructure resilience
Regulatory compliance
Storm sewers
Drains that carry surface water runoff from rain, melting snow, and overflow from lawn water
Storm sewers convey runoff to water bodies such as catch basins, rivers and lakes
Storm sewer components
Above-ground drain at street-level, just below the sidewalk line, and the reservoir piping/tunneling beneath it that carries the water elsewhere
Private storm sewers
A network of pipes, catch basins, and other components that collect and drain rainwater away from homes and businesses
Private storm sewers
Help to prevent flooding, erosion, and water damage
Typically the responsibility of the homeowner or property owner
Regular maintenance is important to ensure proper function
Combined community storm sewers
Single pipe system that combines sanitary sewage and stormwater runoff
Combined community storm sewers
Cost-effective to build
May overflow during heavy rain
Maintenance challenges
Separate community storm sewers
Two pipe network with separate sanitary sewers and storm drains
Separate community storm sewers
Reduced pollution
Higher upfront costs
Long-term benefits
Roof drain system
Consists of roof drains, vertical storm drain pipes (leaders or conductors), and horizontal storm drain
Roof drain systems are designed for draining storm water from low-sloped (essentially flat) roofs
Downspouts are vertical storm drain pipes secured to the building exterior, with a concrete or plastic pad (splashblock) to prevent soil erosion
In locations where the leaders/downspouts can be tied into the sewage system, the system is referred to as a combined sewer
Roof drain systems are commonly placed on low sloped (flat) roofs with at least a 1/4 in/ft slope to ensure water will not pond on the roof
Gutter and downspout system
Crucial part of a building's exterior infrastructure designed to manage rainwater runoff effectively
Functions of gutter and downspout system
Rainwater collection
Water diversion
Protect walls from water runoff
Helping to ensure a dry basement
Preventing soil erosion
Preserve landscaped areas
Components of gutter and downspout systems
Gutter
Downspout
End caps and corner pieces
Hangers and brackets
Gutter guards
Gutter elbow
Types of gutter systems
K-style gutters
Half-round gutters
Box gutters
Seamless gutters
Downspouts
Vertical pipes connected to gutters, directing water from the roof to the ground or a drainage system
Surface drainage systems
Canals with shallow ditches created for runoff water to prevent flooding or pooling on property
Catch basins
Structures designed to collect and hold rainwater and other precipitation runoff from paved surfaces
Catch basins
Capture sediment, debris, and pollutants from surface runoff while allowing water to flow into the drainage system
Typically include a sump or reservoir where sediment settles out before water continues into the piping network
Storm drains
Inlet structures that collect stormwater runoff from the surface and direct it into an underground piping network
Swales
Shallow channels with gently sloping sides used to move water away from buildings, driveways, and parking lots
Swales
Infiltration basins designed to manage water runoff, filter pollutants, and increase rainwater infiltration
Detention ponds
Help prevent flooding by slowing down the flow of stormwater and reducing the risk of downstream erosion and property damage
Retention ponds
Help to recharge groundwater, improve water quality by trapping pollutants, and provide habitat for wildlife
Challenges of surface drainage
Proper maintenance
Cost
Swales
Shallow channels with gently sloping sides
Infiltration basins designed to manage water runoff, filter pollutants, and increase rainwater infiltration
Detention ponds
Help prevent flooding by slowing down the flow of stormwater and reducing the risk of downstream erosion and property damage
Often implemented in urban areas to manage increased runoff from impervious surfaces
Retention ponds
Help recharge groundwater, improve water quality by trapping pollutants, and provide habitat for wildlife
Commonly used in developments where preserving natural hydrology and mitigating flood risk are priorities
Challenges of surface drainage
Proper Maintenance and Cost
Limited Space and Land Use Conflicts
Addressing these challenges requires a holistic approach to stormwater management, incorporating green infrastructure solutions, land use planning, public education, and community engagement