Beach Renourishment:
Are All The Dollars Making Cents?
by DAVE GRANT
"Man marks the earth with ruin. His control ... stops with the shore." (Lord Byron)

By choosing to ignore the dynamic nature of the shore and building along it, humans often find their homes and even whole towns in precarious positions when beaches, as is their nature, move. In the past it was not unusual to simply move structures back away from the shoreline when the ocean threatened. The original building lots along many beaches were purposely long and narrow, extending from ocean to bay. This allowed valuable structures to be moved landward when necessary; a logical solution, but impractical today considering the price of real estate on most shores and the crowding that has occurred on those sub-divided properties. Other obvious solutions like letting the buildings wash away when their time is up, or not allowing construction in the first place, have rarely been considered. Neither idea is a very popular or practical alternative to shore property owners or politicians.

In the last century a variety of schemes have been tried to "save" beaches. These are collectively labeled "hard-technology" - jetties and groins attempt shoreline stabilization; offshore wave-dampening structures to slow the rate of beach drift; and various "sand-grabbing" devices, some of dubious and even humorous design, to capture and hold beach sand in place. None appear to work and most may actually exacerbate the erosion problems on neighboring beaches that are starved of the sand they no longer receive.

Beach replacement or renourishment is a different approach to the problem, and from an environmental viewpoint would appear to be a preferred application of "soft-technology," but even it has problems. Replacement was first tried beneath the eroding bluffs of Long Branch, NJ, in the 1930's and since then on over 400 miles of U.S. coastline - with mixed results. In the last three decades alone the U.S. Army Corps of Engineers has spent around 8 billion dollars on such projects, but the life expectancy of most of these replenished beaches is only a few years, or until a major storm hits.

Some crucial considerations in deciding whether a beach will be renourished, besides the social and political ones, are: sand grain size, source of the fill, and environmental impacts. Particles smaller than the original sand will wash away too fast. Also, there is a limited supply of sand around, and not all of it is available or suitable for nourishment projects (a quirk of coastal geology that is often overlooked by anxious planners and the general public). Regardless, replaced beaches tend to wash away about 10 times faster than natural beaches, most lasting no longer than half a decade. Part of the loss occurs because the offshore slope of the new beach is not replaced and remains unnaturally steep compared to the original beach, encouraging wave attack and increased erosion rates.

The jury is still out on the biological impacts of nourishment. Because of the dynamic nature of burrowing organisms like coquinas and mole crabs that live along the ever-changing shoreline, recolonization of nourished beaches sometimes can be quick. However poor grain size match and the presence of naturally occurring but toxic hydrogen sulfide from silt in the dredged sediments, can inhibit the return of many creatures. Resuspension of pollutants that have accumulated over the years is also a concern.

There may also be some subtle effects on offshore environments when beaches are replaced, and these are still poorly studied. We should worry about the sources of sand and the damage to offshore environments that occur when they are dredged to gather that fill. Neighboring reefs can be choked by dispersed sediments and destroyed by the dredging. Some environmentalists have even expressed concerns that nesting sea turtles might have problems digging through the carbonate "pavement" formed by dredged shell fragments that create steeper, renourished beaches in tropical areas.

Is beach nourishment worth the expense? It is necessary to evaluate each site for environmental impacts, as well as long and short-term benefits to society. Oftentimes, critics of renourishment say the benefits of such projects are exaggerated by vested interests such as local residents and developers, and that most projects are designed to protect oceanfront structures that probably should not have been built in the first place. Also, it can be argued that in light of global warming and sea level rise, the costs will invariably outweigh the benefits in the long run. In short, beach nourishment simply postpones the inevitable destruction of coastal buildings.

At Sandy Hook, the second of two renourishment projects was completed in 1989 using sand from a dredge pit in the Navy's ship channel in Sandy Hook Bay. This fill replaced 750 feet of beach from the initial project that was completed in 1984. Littoral drift washed away that sand and carried much of it toward the tip of Sandy Hook in less than three years - about 100 times the "average" erosion rate along most of the coast. Jetties, groins, and sea walls south of Sandy Hook prevent new sand from reaching here and this exacerbates the erosion problems. Sandy Hook has had priority over other threatened areas because it is a crucial recreation beach for the New York City/North Jersey area and has unlimited access for the public, unlike many of the town beaches farther south.

A third project, recently begun for the beaches south of Sandy Hook, will become the largest renourishment project in history, a quarter-billion dollar effort (some say boondoggle) to buy more time for the North Jersey coast. The project is grand in design, calling for 90,000 tons of rocks for sea walls and groins, and 23 million cubic yards of sand, ten times more fill than was pumped onto Sandy Hook in 1984 (and enough to cover a coast-to-coast, two lane highway with six feet of sand). A big pile of sand and rocks, and a big pile of money.



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Dave Grant was the Monmouth County Coordinator for the New Jersey Shoreline Master Plan.

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