Storm drain inlet protection prevents sediment from entering a storm drain system. Inlet protection can be achieved by the use of filters or impounding an area around or upstream of an inlet to allow sediment to settle. Storm drain inlet protection is a secondary BMP and is to be used in conjunction with erosion control BMPs.
One type of storm drain inlet protection is an inlet filter wherein a frame and filter basket is installed directly into a storm drain drop inlet structure. Another form is a bag designed for use with flat grates (including round) and mountable curbs to filter sediment-laden stormwater. The grate is removed from the frame, slipped into the bag, and then placed back into its frame. There is also an open-top bag that is designed to hang underneath a storm grate to filter sediment-laden stormwater.