Stevens CERL aids in beach replenishment project

By: Melissa Wiegand

Posted: 2/13/09

Stevens has teamed up with the New York District of the US Army Corps of Engineers and the State of New Jersey to work on a beach replenishment project in Long Branch, New Jersey. According to Dr. Thomas Herrington, associate professor of ocean engineering in the Institute's Department of Civil, Environmental and Ocean Engineering and assistant director of the Center for Maritime Systems, this project is just a small part of "the largest beach replenishment project in the world."
New Jersey began its beach replenishment program in the early 1990's. The program's main goal is to extend the width of all New Jersey beaches by a minimum of 100 feet. The state plans to spend a total of $2 billion in order to keep the beaches at this width for fifty years. This will provide buildings and infrastructure along the beaches with greater protection from the flooding that can occur during extreme weather conditions such as hurricanes. Another benefit of the project is that increasing the width of beaches will help to attract more beachgoers. Since the state makes between 15 and 20 billion dollars annually off of beach tourism, the cost of the project is worthwhile.
The stretch of beach in Long Branch that Stevens is currently focusing on was first replenished in 1995. Unfortunately, the replenished beach did not respond as well to erosion as a natural beach would have. Many local surfers have also complained that the man-made shorelines have an adverse affect on surfing conditions. The straight-line shape and steeper drop-off of the new shorelines prevent waves from breaking before hitting the shore. These complaints led the state Department of Environmental Protection to ask researchers at Stevens to develop an experimental sand placement design for the replenishment project.
The project staff at Stevens includes Dr. Thomas Herrington, Professor Jon Miller, three graduate students, and several undergraduate and work-study students. The research group at the Institute's Coastal Engineering Research Lab (CERL)decided to change the shape of the beach by creating a "feeder beach" which protrudes about 700 feet offshore. At this distance from shore, the US Army Corps will have to fill an area submerged in about 25 feet of seawater with sand. The researchers hope that the proposed shape of the beach will allow waves to begin breaking at the outermost point of the feeder beach and roll along the side of it until they reach the main beach, thus improving surfing conditions and preventing rapid erosion of the main beach from a direct assault of waves.
The US Army Corps' relocation of sand from a shoal in Sandy Hook to Long Branch began in early December, 2008. They completed the transfer in the first week of February. "About 700,000 cubic yards of sand - the equivalent of 70,000 dump truck loads - were moved to the Long Branch shoreline," stated Dr. Herrington. He said that it only cost about $5.6 million to transport the sand. When asked about the environmental impact of the dredging, Herrington insisted that "the shoal in Sandy Hook builds up quickly and is often dredged in order to allow ships to sail through the region" and that the impact on the ecosystem there is short-lived, because the species affected by the dredging are able to recover within a year or two.
In addition to designing the shape of the new shoreline, the CERL will be responsible for monitoring the erosion, creation of sandbars, and wave dynamics along the shore. The research group will use wave runners customized with GPS and echolocation systems to keep track of the changes along the beach. These "Dynamic Underwater Coastal Kinematic Surveying" (DUCKS) systems will be able to survey the coast much more efficiently than the swimmers who used to dive up to 15 feet beneath the surface with surveying equipment. Herrington says the DUCKS will take readings along 45 survey lines for about 18 months, or "until less than 20 percent of the initial volume of sand in the feeder beach remains." They will also set up cameras on the beach, which will be used to assess the number of surfers using the beach, and the quality of the waves. In the fall of 2009, Herrington hopes to expand the Long Branch project by building a submerged artificial reef offshore.
Since the development of the Coastal Protection Technical Assistance Service (CPTAS) at the Institute, Stevens has been involved with several beach replenishment projects. CPTAS was created to both inform and counsel New Jersey citizens and government officials about coastal protection technology. Through this program, faculty and students from Stevens often serve as technical engineering consultants for the state of New Jersey.