LID Control

LID controls are low-impact development practices designed to capture surface runoff and provide some combination of detention, infiltration, and evapotranspiration. They are considered to be properties of a given sub-catchment, similar to how aquifers and snow packs are treated.

SWMM can explicitly model the following generic types of LID controls:

• Bio-Retention Cell - These are depressions containing vegetation grown in an engineered soil mix placed above a gravel drainage bed
• Garden - are a type of bio-retention cell consisting only of the engineered soil layer, with no gravel bed below it
• Green Roof - are another variation of a bio-retention cell that has a layer of soil over a special drainage mat that transports excess rain percolated from the roof
• Infiltration Trench - These are narrow ditches filled with gravel that intercept runoff from impermeable areas of the slope
• Pervious Pavement - These are excavated areas filled with gravel and paved with a mixture of concrete or porous asphalt
• Rain Barrel - These are containers that collect runoff from the roof during storm events and can release or reuse rainwater during periods of drought
• Rooftop Disconnection - Discharges to front landscaped areas and lawns rather than directly into culverts
• Vegetative Swale - These are channels or depressed areas with sloping sides covered with grass and other vegetation