A Risk Assessment of the Impacts of Coastal Flooding and Sea Level Rise on the Existing and New Pump Stations 113, Norfolk, VA

The author assessed the risk to a wastewater pump station and a planned replacement located nearby due to coastal flooding and rising sea levels. The locations for the pump stations are in the Larchmont neighborhood by the Lafayette River tidal estuaries in Norfolk, Virginia. The Lafayette River is a tributary to the Elizabeth River, which flows to the Chesapeake Bay. The low-lying areas along the river are subject to coastal surges caused by tropical and extra-tropical storms that flood the bay. The region is considered one of the urban areas most exposed to the accelerating rate of rising sea levels. Six of the highest storm surges on record have occurred since 2003 and even more moderate events have inundated the existing pump station. The flooding impacts the service and reduces the life cycle performance of the pump system. The study compares the vulnerability of the existing pump station to an alternative to replace the station in a new location. It uses systems engineering to define the challenge caused by coastal flooding and future sea levels, and risk-informed decision methodologies to define the exposure. The findings show that the investment in a new pump station reduces relative risk due to coastal flooding nearly fivefold; but over the 50-year life cycle of the pump station the risk increases again because of higher sea levels