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Delaware Department of Transportation

Stormwater Management

What is the Stormwater System?

Drain description The stormwater drainage system is a route of drainage for precipitation (rain or snow). Once the precipitation hits the ground and starts to flow over land it is called runoff. Runoff can carry with it materials from highways, streets, and gutters into the stormwater drainage system. This runoff can carry harmful materials (such as gas, oil, pet waste, fertilizers and pesticides) to streams, ponds, and rivers making them unsafe for drinking, fishing, swimming, and other activities. Prevention of contaminated runoff is a growing concern across the nation.

Stone Creek Dam
Swale with Check Dam

Stormwater drainage systems are designed to control the quantity, quality, timing, and distribution of runoff. Other objectives in the design of stormwater management systems include erosion control and groundwater recharge.

Drop Inlet
Drop Inlet

A stormwater drainage system collects surface runoff via inlets in road pavements and routes it to a treatment unit and/or receiving body of water, usually through underground pipes called storm sewers. In some cases, the surface runoff is discharged directly into a receiving body of water such as a stream, river, lake, or ocean.

Inlet with Markers.

An inlet is where the water enters the storm sewer/drainage system. DelDOT is in the process of marking each inlet in its storm drain system with a medallion that reminds people that anything that is put into a storm drain eventually ends up in our water - "Only RAIN down the storm drain!"

Curb Inlet

An outfall is where the stormwater exits the storm sewer/drainage system. Pipe outlets are constructed in numerous shapes, sizes, and materials. Round and oval pipes made from reinforced concrete, corrugated metal, or plastic, are most commonly used. Ditches and low-lying or depressed stretches of land (swales) are also used as outlets to convey stormwater into and out of the storm sewer system. They usually carry stormwater from pipes, lack a defined geometry and are often lined with concrete, rocks, or grass.

Storm Drain Marker

DelDOT is one of a large number of local and national agencies that help maintain the water quality of our local waterways. We routinely maintain stormwater drains and storm sewers to make sure that they are free of silt and debris so that the rainwater can flow freely.

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