What is the function of an underdrain in detention facilities?

The function of an underdrain in detention facilities is primarily to filter stormwater. Underdrains are designed to facilitate the movement of water away from the detention area, helping manage groundwater levels and reduce the potential for water saturation in the facility. As stormwater percolates through the soil layers, underdrains collect water that has passed through these layers, effectively allowing debris and pollutants to be filtered out. This filtration process is essential in ensuring that the water being discharged meets quality standards before entering adjacent water bodies.

While underdrains do play a role in the broader aspects of stormwater management, such as assisting in the regulation of water levels to prevent flooding, their primary role within a detention facility is focused on the filtration and collection of treated stormwater rather than simply releasing it or serving as the main drainage system.