What is the most common reason for large amounts of sand, gravel, and grit entering a wastewater treatment plant?

The most common reason for large amounts of sand, gravel, and grit entering a wastewater treatment plant is related to storm events. During heavy rainfall, surface runoff increases significantly, which can wash debris and sediment from streets, parking lots, and other surfaces directly into the sewer system or stormwater drains. This influx often includes large quantities of sand, gravel, and grit, which can overwhelm treatment facilities that are not designed to handle such high sediment loads.

In contrast, while plant malfunctions, construction activities, and seasonal flooding can also contribute to increased debris in a wastewater treatment facility, these situations are typically less frequent or less significant compared to the impact of storm events. Plant malfunctions tend to involve internal issues rather than external debris, construction activities are usually localized, and while seasonal flooding can introduce sediment, it is often the more intense and widespread nature of rainstorms that causes the most significant uptick in grit and sediment entering treatment systems.