During periods of heavy rainfall, the wastewater volume in a sewer system can exceed the capacity of the sewer system or treatment plant.
These overflows, called combined sewer overflows (CSOs), contain not only stormwater but also untreated human and industrial waste, toxic materials, and debris. They are a major water pollution concern for the Chesapeake Bay.
Current research is revealing that stormwater can carry pathogens and that this stormwater is entering wastewater treatment facilities. During periods of intense rainfall, not only can stormwater carry higher amounts of pathogens, but it also increases the flow rate of the wastewater treatment facility. When the flow rate exceeds the facilities’ treatment capacity it can impact treatment performance. Even relatively moderate rainfall events could create instant surface run-off and the overtopping of sewers already close to maximum capacity.
While the Cape Charles plant is generally equipped to handle high flow water, consistent rain events may still pose a problem. Below are the figures reported by the town for the last month, which indicates that water is exceeding wastewater flow to the plant.
The numerous beach closures and testing that has confirmed that a consistent human signature is present in the bacteria content, a closer watch on wastewater performance should be considered.
The town has purchased upgrades to the current mixers currently employed at the plant, so this may considerably during high water events.