Help or harm in sand dredging?

Beach replenishment supports the local economy by protecting coastal communities from damage caused by severe storms.  Beach towns depend largely on tourism to support their economy, but protecting property – not improving tourism – is the primary goal of beach replenishment.

Less talked about are the negative effects dredging can have on wildlife and the surfing community.  In Rehoboth and Dewey Beaches, surfers and swimmers say replenishment projects have damaged local beaches.

According to Stephen Rochette, of U.S. Army Corps of Engineers, beach replenishment in Dewey Beach and Rehoboth Beach is expected to begin in October. Rochette said in an email the federal Flood Control and Coastal Emergency Program awarded Great Lakes Dredge and Dock Company a contract for $22.7 million to repair erosion caused by the November 2009 nor’Ida storm, to beaches in Rehoboth, Dewey, Bethany, South Bethany and Fenwick Island.  He said the corps received an additional $7.5 million to fund work in Rehoboth and Dewey Beach.

Rochette said sand will be pumped from 16 miles offshore, in an area referred to as the Fenwick Island borrow area, which was approved by Delaware Department of Natural Resources and Environmental Control and has been used for other beach replenishment projects in Delaware.

The corps has to return every three to six years to renourish the beaches, but projects depend on available funds, Rochette said.  Beach replenishment is essential to protecting the infrastructure of coastal communities. “Beach nourishment represents the most cost-effective and least environmentally intrusive way to construct a level of protection for a community,” Rochette said.

Some experts say the disadvantages of pumping sand on the beach outweigh the advantages.

“In the long run, beach renourishment probably does more harm than good,” said geologist and Western Carolina University professor Rob Young, in a 2005 testimony for the House of Representatives Natural Resources committee.  Young said the high cost of beach replenishment and its limited effectiveness in major storms makes it not worth taxpayer money.

Young said erosion is natural, and it does not cause the beach to disappear. “What does cause the beach to disappear is the placement of a seawall or a row of buildings in the way of this retreating shoreline. So if a beach is disappearing due to erosion, it is because most developed beaches can no longer respond naturally to shoreline retreat,” Young said.

According to a report from geology professor Don Barber, of Bryn Mawr College in Pa., nourished beaches erode two to three times faster than natural beaches.  “The factor for the lifetime of a nourished beach is the number of storms that affect the beach,” Barber said.

Replenishment projects can also affect the survival of certain species. Barber said water that is too muddy could effect the survival of filter feeders like clams.  Muddy sediments can also contain toxic material, he said.  “In recent decades, a variety of plants, insects, turtles, shorebirds and other animals have become threatened or endangered as a result of human alteration of beach environments,” Barber said.

Barber said differences in the size of the grains of sand being pumped from offshore can affect the way waves interact with the beach.  “This will affect surf conditions,” he said.  According to University of Delaware, 429 people were injured in the surf zone – the area between where the ocean meets the shore and where waves break – of Delaware beaches last year.  Wendy Carey of Delaware Sea Grant College Program and Paul Cowan, chief of the department of emergency medicine at Beebe Medical Center, are conducting a study to discover the main causes of surf zone injuries.

“I don't think that beach replenishment in itself is the largest causative factor in these injuries.  If it were, I would expect to see a more uniform distribution of injuries day to day.  It may very well be a factor but there is something else, or multiple factors, that is causing the episodic nature of these injuries,” Cowan said in an email.

Carey said in an email that location, weather conditions and medical records are all factors related to surf-zone injuries.

Dewey Beach Lifeguard Capt. Todd Fritchman said in an email he has not studied the frequency of injuries related to replenishment.  “However, generally speaking past replenishment projects have resulted in various types of hazards that we were not accustomed to,” he said.

Cape Henlopen High School teacher and longtime surfer Ben Evick said he thinks sand dredging has its drawbacks.  "Whenever there is beach replenishment, we have seen breaks disappear.  Rehoboth used to break all over town, when the beach replenishment happened the sand bars were gone," Evick said.

Evick also said beach replenishment on the Delaware coast seems to cause more injuries because waves break where they naturally would not, and cause large drop-offs.

Sand dredging in Rehoboth Beach and Dewey Beach in 2005 resulted in stones and gravel being pumped onto local beaches.  DNREC officials have said sand will be pumped from a borrow point near Fenwick Island, which has in the past produced sand that was relatively free of gravel.