A significant portion of New York City’s 565 miles of shoreline is littered with deteriorating structures in desperate need of rehabilitation or replacement, especially in the wake of Hurricane Sandy, which revealed the serious vulnerability of the region’s waterfront. However, the rising cost of construction materials and labor, outdated construction methods and technologies, changing regulations, and a host of other factor have made waterfront construction projects prohibitively expensive in recent years.
Andrew Rella, a Stevens Ph.D. student in Coastal Engineering program, has developed an award-winning proposal for an innovative, ecological and cost-saving solution for completing New York City marine construction projects. His proposal – which calls for wave pump technology to attract oysters to marine piles – won $25,000 for taking second place in the Change the Course of the New York City Economic Development Corporation (NYCEDC), a non-profit organization that promotes economic growth across the five boroughs.
Rella’s proposal – a direct extension of his doctoral research – demonstrates how using wave pumps that utilize the ambient energy in the marine environment to transport water from one location to another will encourage oyster growth on marine piles that support the piers and docks of New York City’s waterfronts, which can both reduce maintenance costs and improve water quality.
Typically, the thousands upon thousands of piles around New York City are made of wood and encased in protective concrete, a material which degrades over time and needs to be continually replaced. Encasing just one pile in concrete can cost more than $12,000.
Since oyster growth has been shown to exponentially strengthen concrete in a period of only several years, Rella proposes constructing oyster reefs on the piles by placing a durable net around them filled with oyster shell and seed. The process would cost less than 3percent of the expense to encase piles in concrete.
“As the oyster reef develops around the piles, the oyster’s calcium carbonate shells cement to each other and the structure, strengthening it as well as protecting it from the erosional forces of the waves,” said Rella, who earned his B.E. in Environmental Engineering and M.E. in Coastal Engineering from Stevens. Adult oysters can filter up to 50 gallons of water a day, having significant environmental benefits on the surrounding area.
Rella’s research also shows how the careful placement of wave pumps around the piles encourages additional oyster growth, further strengthening the piles. The wave pumps – vertical pipes with one-way valves that are fueled naturally by the motion of waves or even the wakes produced by ferry activity – would transport nutrient- and oxygen-enriched water from the surface to deeper areas.
“Normally the water conditions and food supply that oysters need to survive is available on the surface,” said Rella. “By pumping it deeper in the water column it encourages the growth of oysters where it would normally not be possible.”
Rella – a native New Yorker who plans to dedicate his career to improving the condition of the Hudson River – has conducted research on the design of coastal structures, habitat development along shorelines, the sustainability of water resources, and alternative power supplies. His major focus has been the study of "living shorelines" – the incorporation of vegetation and other natural elements into the design of coastal structures, which are normally solely constructed from concrete or rock.
“These traditionally ‘hard’ concrete structures have resulted in the loss of habitat along our shores and our aquatic ecosystem has suffered greatly,” said Rella. “My proposal is an innovative approach for applying the idea of living shorelines to our urban shores. I believe oysters will prove to be the foundation of any healthy ecosystem development in the region.”
The NYCEDC, launched the Change the Course competition in November 2012. It sought innovative proposals to help the New York City build and maintain waterfront infrastructure in a more cost effective and sustainable manner.
Participants competed for a chance to win a cash prize of $50,000 and see their ideas incorporated into future NYCEDC waterfront projects. After submitting formal proposals of their ideas, selected finalists presented them to an exclusive field of New York City agency representatives and maritime construction professionals, at which point the winners were chosen.
Rella was officially recognized at the Change the Course Symposium on April 10, 2013 in New York City, where he presented his ideas along with other award-winners and took part in a Q&A and networking session.
“Andrew's innovative work synthesizes much of what he learned as an undergraduate in the Environmental Engineering program at Stevens with his current graduate work, and offers the promise of transforming the waterfront construction industry,” said Stevens Research Assistant Professor Jon Miller.