Category 1

Studies, Research and Consulting Engineering Services

OUTSTANDING PROJECT

South Bethany Tidal Pump System (DE)

The canals of South Bethany may soon be flushed clean thanks to an innovative tidal pump system that will circulate canal water to the Atlantic Ocean and return clean seawater via a network of underground pipes. Like many canal systems worldwide, water quality in South Bethany’s canals is severely degraded. Poor circulation, sediment accumulation, low oxygen levels, excessive nutrients, and pollution have led to declining shellfish communities, pungent and harmful algae blooms, and fish kills. Based on a concept developed by Lloyd Hughes, a former councilman and retired engineer, the town of South Bethany commissioned the team of Oceaneering International Inc. and KCI Technologies Inc. to evaluate the feasibility and develop preliminary designs for a tidal pump using only tidal differential to power the system. Engineers explored possible scenarios for alignment, configuration, materials and construction methods to further define the tidal pump concept and determine a potential cost and implementation schedule. Effective hydraulic analysis posed a crucial design challenge because of the low head differential and resulting low operating velocities. To deliver the required circulation through the system, each component had to be optimized for flow performance by reducing friction wherever possible. “The modeling scenarios took creativity to reflect the varying environmental and fouling conditions,” said KCI Vice President Tim Wolfe, PE. “Possible marine growth like barnacles had to be considered as impediments to the low velocity water.” The first of its kind, the tidal pump system will utilize almost two miles of underground piping, two ocean outfalls located 30 feet below sea level, and an innovative diffuser system configured to dissipate velocity during the exchange. Once constructed, residents could see improvement in water quality in as little
as a month, as the tidal pump fully flushes the canals every 30 days.