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What is the difference between a Catch Basin, Drop Inlet, and Sediment Trap?

A Catch Basin is a term used specifically in Municipal Maintenance. It refers to all curb inlets of the storm drain, whether or not they provide any water quality benefit.

Drop Inlet is any inlet or drain that conveys stormwater from the surface to the storm drain. These structures possess less than 1 foot of a sump, and do not provide any water quality benefit. These are not modeled in our pollutant reduction model.

Sediment Trap is also an inlet that conveys stormwater from the surface to the storm drain, but possesses a sump of 1 foot or more and therefore provides a water quality benefit. The are modeled in our pollutant reduction model. 

Catch Basins is a term that refers to both Drop Inlets and Sediment Traps. Simply put, it is any structure that conveys stormwater from the surface to the storm drain, regardless of whether or not it provides any water quality benefit. Since the Municipal Maintenance Module's focus is on cleaning these structures, we've automatically filtered the BMP map to only display Drop Inlets and Sediment Traps.