Hafner

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GALLOWAY— A stable shoreline and wide beaches support tourism and recreation and prevent storm damage of properties, loss of infrastructure and wildlife habitat.

Steven Hafner, assistant director for Coastal Research Center, said barrier islands were formed about 18,000 years ago when sea level began to rise as glaciers melted.
He said in our state, there are only about 31 miles of undeveloped shoreline remaining. A total of 76 percent of our state’s shoreline is heavily developed, “Which forces us to think about how do we draw that line in the sand and protect that development and that expense that we put into developing these commercial properties, houses and infrastructure,” he said.

Shoreline development is the result of a lack of understanding of coastal processes and unwise land use policies where building on the beach was done for profit, said Hafner.

“Whether we believe in global warming or not, there certainly is enough evidence that states that sea level has risen and is going to continue to rise in the future,” he said. “What kind of rate, we’re not sure.”

He said barrier islands have moved landward as sea level has risen.

“Barrier islands are nothing more than long, narrow offshore shifting sand deposits that separated are by tidal inlets…” said Hafner.

He said the forces of Mother Nature: sea level rise, waves, currents, tides and storm events affect barrier islands. Storms surge and waves push sand back to marsh areas, which raises that elevation, and over time the beach retreats.

Wood and rock groins have been built to protect the beach as well as seawalls, jetties, submerged sills and breakwaters. Groins trap sand that is traveling in the onshore drift with sand building up on the up drift side with loss of sand on the down drift side, said Hafner.

He said often a number of groins are built down the beach in order to avoid “scalloped” beaches. He said Cape May has a terminal groin (at Third Avenue) which causes a major offset of the beach along the Lower Cape May Meadows due to sand starvation.

If you take a trip on the Cape May-Lewes Ferry, you will see a large breakwater that protects the ferry terminal in Lewes from wave assault and creates a sheltered harbor. A scalloping effect may occur where sand is stripped from adjacent beaches and accumulates directly behind the structure, said Hafner.

Soft structures include building dunes, planting vegetation and installing geotubes.
Seawalls are great for protecting properties and infrastructure but can have a devastating effect on a beach located seaward of the wall, said Hafner.

He said some innovative ideas have been tried to protect the coastline with mixed results. A beach saver reef, a concrete structure offshore from the beach, designed to allow sand to move over the structure on the seaward side but retain it on the landward side, was installed off Cape May Point. A double “T” concrete structure was also installed but a rock foundation was not installed under the structure and it has been buried in the sand.

The beach saver reef stayed intact on its ends and is still functioning but settled a bit in the middle allowing some sand to escape, said Hafner. At two beaches in Cape May Point, the reefs performed so well that some sand had to be removed to make it safe for swimmers.

Beach renourishment can be accomplished with an offshore dredge. A recent bid for the Sea Isle-Strathmere project came in at $2.9 million just to get equipment such as barges, tugs, bulldozers, pipeline and a dredge on site, said Hafner. Equipment may come from as far away as the Gulf of Mexico or New England, he said.
The price for sand was $7 per yard.

Sand can be hauled in by truck. While the mobilization charge may be only $40,000, handling costs of delivery and spreading sand on the beach is $17.50 per cubic yard. In the process, a seemingly endless caravan of sand-hauling trucks may damage local roads and bridges, said Hafner. He said hauling sand was efficient for emergency repairs after storms and restoring dunes but not good for large projects.

Back passing moves sand by trucks from a down drift beach where sand has been collecting to an area of beach that has been eroding. Cape May and Avalon have used back passing this year.

“The idea of this method is to try and prolong the need for the next large-scale renourishment project,” he said.

Hafner said a back passing project has mobilization costs similar to sand delivery by truck, about $70,000 but the cost per cubic yard of sand is much lower, comparable to hydraulic dredging.

Avalon is scheduled to receive beach renourishment every three years at a cost of $16.7 million for three dredge projects. By using back passing, enough sand can be moved to maintain an eroding beach for 11.5 years reducing the need for frequent maintenance cycles.
Savings for back passing as opposed to a dredging project over three nourishment cycles could amount to as much as $9 million, said Hafner.

“The nice thing also is we’re only recycling 900,000 cubic yards of sand that is already in the system whereas traditional renourishment requires us to place another 1.2 million cubic yards on the beach,” he said.