Catch basins are surface water inlets that have a sump to collect solids. The device allows for water to flow through into a network of pipes. Catch basins are used to capture debris, and pollutants. However, fine particles - like silt or sediment - are small enough to pass through the basin. The performance of catch basins are dependent on the design of the basin itself, including size, and routine maintenance of storage space in the sump.
Catch basins can be used for different types of land use applications. They are typically used in places in places where large solids need to be removed, and a routine maintenance schedule can be followed. Catch basins are often built at the curb of a street, or below ground; however, basins should not be use in places discharges can pass directly into surface waters.
When designing a catch basin, storage depth and maintenance are the primary considerations. The deeper the basin, the more efficient water retention and hydraulic turbulence become. Solids removal becomes affected when the storage depth is 40-50% full. When the catch basin reaches this level, solids can be washed out of the basin – which is why maintenance is so important.
Maintenance should be performed before the catch basin is half full. This task typically consists of trash and debris removal. Maintenance workers often keep a log of the amount and types of objects collected in the basins. It is recommended that catch basins be cleared out twice a year at minimum. Frequent maintenance can result in increased performance, especially in industrial or commercial areas. Safety must be considered for catch basin maintenance as high pollutants – such as oils, metals, etc. – could potentially contaminate surface and groundwater.
Additional considerations for catch basins include basin inserts and catch basin covers / screens. Catch basin inserts are used to filter runoff from entering the basin. These typically come in two styles, a series of trays or a filter fabric. Catch basin covers or screens can be used to initially stop trash or large debris from entering the network of pipes. Other options for catch basins may also be available.