External stormwater diversion structures, specifically diversion wells, are designed to manage and control the flow of stormwater during heavy rainfall or storm events. These structures are typically located outside buildings or infrastructure and are used to redirect excess stormwater away from vulnerable areas.

A diversion well is a specific type of external stormwater diversion structure. It consists of a large underground pit or chamber that collects and temporarily stores stormwater runoff. The well is usually connected to a system of pipes and drains that capture stormwater from rooftops, parking lots, or other surfaces.

When heavy rainfall occurs, the diversion well collects the excess stormwater, preventing it from overwhelming the local drainage system or causing flooding. The well is designed to have a certain capacity, and once it reaches that capacity, a controlled outlet or pump system is used to redirect the collected stormwater away from sensitive areas.

By using diversion wells, the stormwater runoff can be effectively managed, reducing the risk of flooding and minimizing potential damage to buildings and infrastructure. These structures help control the flow of water, prevent erosion, and protect the surrounding environment by allowing sediment and pollutants to settle before the water is released.