Retention basin volume must be recovered within what time frame?

The correct answer is that the retention basin volume should typically be recovered within 72 hours. This time frame is crucial for effective stormwater management and helps ensure that the basin can adequately handle subsequent rainfall events. A 72-hour recovery period allows for the gradual release of accumulated water, which reduces the risk of downstream flooding and allows for sedimentation processes to occur naturally within the basin.

This period also aids in maintaining hydraulic function and ecological balance. For instance, if water remains in a basin for too long, it can lead to issues such as mosquito breeding or water quality degradation. The 72-hour timeframe strikes a balance between managing immediate runoff following a storm and ensuring that the retention basin operates efficiently and effectively for future storms.

While shorter recovery times might seem efficient, they may not provide sufficient capacity for groundwater recharge or sediment settling. Conversely, longer recovery periods can lead to the previously mentioned adverse impacts. Hence, 72 hours is established as a standard to optimize both stormwater management and environmental health.