CREDIT: Smith-Midland Corporation
Ocean Gate, a little town of 2,200 people on Toms River in New Jersey was hit hard by Superstorm Sandy. Almost half of the homes in Ocean Gate suffered serious damage from floodwater and 65 percent of the boardwalk was washed away.
Given that level of destruction, perhaps it’s not surprising that this picturesque Jersey shore town is investing in beach defenses reminiscent of barricades set up along the English Channel during World War Ii. This time, however, the barriers aren’t intended to keep out enemy boats — the enemy here is the ocean.
The defenses are called “beach prisms” — triangular concrete wedges that look a lot like highway barriers with giant slits cut through them. When placed just off the beach, they create a porous underwater wall that disperses wave energy before it can scrape sand from the beach. Because of the large slits, the prisms also help to naturally replenish beaches — wave and wind action push water and sand through and the sand accumulates at the shoreward base of the structure.
The Ocean Gate project is the first time this sort of erosion prevention method has been used in New Jersey. The structures resemble beach defenses of WWII because they were inspired by the observation that similar-looking barricades designed to keep tanks off of beaches in Britain, seemed to attract mounds of sand around them.
Thirty-five beach prisms arrived at Ocean Gate at the end of November and on Monday, the first five were placed in Toms River about 50 feet from the sand. Each prism is about four feet high and ten feet long and will just be visible from the beach.
Beach prisms are a relatively economical solution to tackling beach erosion. The three sections of beach prisms planned for Ocean Gate are expected to cost around $150,000, or $1,275 per prism, far less than sand berms or rock riprap which could cost upwards of $1 million for the same length of waterfront.
Smith-Midland, the Virginia-based manufacturer of beach prisms, has been testing the structures at 20 sites in the Chesapeake Bay area for years. Beach prisms are also being used off of Wallops Island, Virginia, to help protect the end of a runway at the NASA launch facility and on the north shore of Oahu in Hawaii to protect homes from winter surf.
Since Superstorm Sandy, most communities along the Jersey shore have been focusing almost exclusively on building artificial dune systems to protect homes from future storms. While well-constructed and-intelligently oriented dunes saved towns like Harvey Cedars, Surf City, and Brant Beach from the catastrophic devastation endured by communities with no dunes, the cost of maintaining huge piles of sand which are routinely eroded by frequent coastal storms may not be sustainable. Climate change is expected to lead to more intense and frequent storms, which will make keeping sand on beaches even harder in the future.
Beach replenishment projects, which began in earnest along the Jersey shore in the 1980s, have dumped 73.2 million cubic yards of sand on the coast to keep the Atlantic Ocean at bay. The vast majority of the $556.8 million that these projects have cost is picked up by the federal government. Municipalities pay just $87,000 for every $1 million in federal funds.
Because they are porous and relatively low, beach prisms alone won’t protect a town from high water, but they would help protect the precious sand dunes that stand in between the angry ocean and billions of dollars of property.
Rodney Smith, CEO of Smith-Midland said in a phone interview that his company has been inundated with inquires about beach prisms in recent weeks.
“We’ve had so many people, so curious about what we’re making,” he said. “We been testing and perfecting for nearly two decades, and now, all of a sudden, everyone wants to know about beach prisms.”