Beach Master

IF SOMEONE WERE TO ASK YOU ABOUT THE TECHNOLOGICAL marvels of Coney Island, the roller coaster might first come to mind (it was born there in 1884) and then, perhaps, the blazing amusement parks that dazzled turn-of-the-century crowds with their prodigal use of electricity. As it turns out, though, the wide sandy shore itself is perhaps Coney’s greatest engineering innovation.

Eighty years ago the Coney Island shore became the first artificial beach in the world. This was, according to one reporter, “a startling scheme, like everything at Coney Island.” It transformed a narrow, in places nonexistent, beachfront into a great, welcoming expanse that could accommodate a million visitors over a hot summer afternoon. What’s more, this beach could be enjoyed for a five-cent ride on another of the city’s new technological wonders, the subway.

However, plenty of cities had subways; but no other municipality had ever thought of creating a beach. The closest projects had been attempts by engineers in England and America to stem beach erosion in the early 1820s. They had designed underwater seawalls (called groins ) perpendicular to the shore to capture the sand that was washing past with the current. In the United States these projects were done up and down the Eastern Seaboard: Martha’s Vineyard, Massachusetts; Sullivans Island, South Carolina; the St. Johns River mouth at Jacksonville, Florida.

But these systems barely worked. The captured sand was inevitably diverted from its natural destination to beaches downcurrent, which would then also start to erode. Until Coney Island, no one had any effective way to move sand ashore and keep it there. Then again, no one was facing the situation New York City was in the early 1900s.

New York City’s booming population at the turn of the twentieth century created a public health problem for it. During the steaming summer months, disease rates exploded in the crowded tenement districts. The wealthy could escape to the Long Island or New Jersey shores; the growing immigrant population could get to Coney Island, but to gain access to the rocky shore, they had to stand in lines that sometimes stretched for more than a mile, waiting to pay admission to one of the many private bathhouses lining the water’s edge.

City officials were desperate to create an extensive seaside park where the poor could enjoy what was considered cleansing salt air. Given its site at the end of the newly planned public transit system, Coney Island was the logical choice. Because there was no real beach there, plans were drawn up that called for a boardwalk at the water’s edge with a wide, green park and inland esplanade. But property owners were not willing to let go of their waterfront land.

Philip Farley, an engineer for the borough of Brooklyn, observed the property battle and proposed building a boardwalk at the current shoreline, and then suggested creating a beach in front of it, filling in Coney Island’s state-owned tidelands with white sand. Private landowners have no claim on the ocean, Parley reasoned, and he decided that by using sand dredged from the nearby ocean floor, he could conjure up a two-million-square-foot bathing beach in Coney Island’s public waters. Purchased, such land would cost several million dollars. Instead, Parley said, he could engineer and build the sandy shoreline for under one million dollars. He estimated that constructing the vast seaside park, with a boardwalk wider than Fifth Avenue, would cost the city about four million dollars.

On the one hand, New York City was the perfect setting for this project. The Brooklyn Bridge had been hung across a river, rapid-transit tracks were being laid underground, and the Woolworth Building was the tallest skyscraper in the world. But all this engineering innovation notwithstanding, very little was known about the physics of coastal processes.

Even though manipulating waterways goes back to 3500 B.C. , civil engineers in the early 1900s still had no mathematical models to help them understand coastal processes. Egyptians pioneered breakwaters to protect their harbors, and Romans introduced dredging for ship channels, but the closest thing to a textbook on coastal sand and wave action was a compilation of drawings by Leonardo da Vinci.

The poor state of the field was well known to people who frequented Coney Island. During the late nineteenth century, many bathhouse owners had attempted to widen the meager plots in front of their properties. All of them failed. Not only were their sand-catching groins unsuccessful, but because of Coney Island’s particular orientation to the currents, they actually hurt the existing shoreline. Parley wrote that even though there were at least 30 groins in place at Coney, “taken as a whole, the beach had been eroded, losing at some points substantial amounts.”

Property owners, suspicious of Parley because no engineer had yet been able to avert the continual storm damage that plagued Coney, went to public hearings about the proposed construction, and with no technical data on coastal processes, the borough of Brooklyn’s chief engineer, Louis Risse, could not respond to their vehement protests. It’s very possible that even the city’s chief engineers were skeptical about Parley’s plan. He had first talked of constructing the beach in 1903, but his scheme was announced to the public only in 1914, when his proposal had made it past the powers that be and into the news. It was fortunate timing too. That summer Coney Island saw record crowds that required policemen to keep order among the lines of waiting bathers. Parley’s plan was approved, and in October 1921 a construction contract was signed.

FARLEY AND CITY PLANNERS CALCULATED THE WIDTH OF boardwalk they’d need by using attendance figures from the Atlantic City boardwalk and taking into consideration Coney Island’s wildly popular late-summer Mardi Gras celebration. They settled on a generous width of 80 feet. The height of the boardwalk—some 13 feet above normal high tide—was set by technical requirements, chief among them the amount of space needed to accommodate the sand fill that would be pumped in. Finally, the design of the boardwalk was dictated in large part by a fashion of the time: rolling chairs. Rolling chairs, in which visitors were pushed along the boardwalks, were the vogue at Atlantic City, and Parley specified that the planks be laid at a diagonal just one-eighth inch apart to allow the occupants the smoothest possible ride. For the same reason, he designed ramps to the boardwalk at each street intersection, which had the happy effect of making the structure handicapped accessible years ahead of its time.

The boardwalk was finished on schedule, and while its construction was what captured the interest of the general public, it was the beach-fill part that excited the engineers of the day.

As the concrete piles that would carry the boardwalk were poured and began to be placed, Parley had workers start on building the groins: 16 of them, spaced 600 feet apart, running 360 feet into the ocean, and angled slightly to the southeast to guard against the Long Island coast’s most damaging waves. Each groin had two sections: the onshore, constructed of wooden piles treated with preservative, and the offshore, a solid stone jetty about 200 feet long. The near-shore portion was meant to serve as a basin wall that would hold in place the sand pumped ashore. The stone jetties would serve as a breakwater, to slow the sand being carried away.

The stone parts of the walls, Parley mandated, should be built with granite, known for its resistance to the chemical and physical action of seawater. Moreover, granite was available in the range of sizes his blueprints required, from 100-pound rocks up to 10-ton boulders. The smaller rocks would form the core of the jetties and help fill the voids between the larger stones on the outside. By thus preventing gaps in the jetties, Parley’s design made them both stronger and more durable.

Picking the material for the jetties was easy; placing the outsized stones in precise spots underwater was not. Because the rock was being brought directly to the site by ships from quarries in Massachusetts and Maine, Parley dictated that before they left the quarries, the stones should be drilled and fitted with hooks. Once at Coney Island this allowed specially equipped barges to place them carefully in the jetties, rather than use the more conventional but haphazard method of laying them in with chain harnesses.

As the contractor finished the protective groins during the winter of 1921-22, a number of severe storms hit the area. The offshore ships responsible for the construction were hastily outfitted with extra anchors. Despite the weather, by August 120,000 tons of stone had been loaded, shipped, unloaded, and placed without any injuries, completing the groins and allowing the start of the most novel part of the project.

Filling in the space between the 16 groins is what fundamentally separates the Coney Island Beach project from any earlier shore-building effort. It was a monumental inaugural attempt to pump sand inland from the ocean floor. The total quantity dredged and placed on Coney Island Beach was 1,700,000 cubic yards, enough to fill 100 football fields 10 feet deep. Parley accurately calculated the amount of sand necessary to advance the high- and low-water marks 330 feet seaward, adding that much room to the beach for bathers.

The contractor pumped the sand ashore with a single 1,000horsepower steam-powered dredge. Virtually all dredging work at the time was very different: scraping open navigation channels for ships in the area. Still, this dredge required only one modification. Because clearing ship channels often means routing out ocean floors, dredges have cutters. Once a cutter successfully dislodges dirt and rock, a suction pipe gathers the material and pumps it elsewhere. But since Parley only wanted more fine white sand, the cutter device was jettisoned. Suction alone propelled the sand up and onto the beach, through a steel pipe 20 inches in diameter.

Probably the biggest challenge lay in how to distribute the sand evenly over a strip of land almost two miles long. Parley’s contractor finally decided to pull sand from four offshore locations; this ensured that the maximum pumping distance to the beach never exceeded 3,500 feet.

THE FILL PROCESS DID NOT GO AS SMOOTHLY AS THE building of the groins. The problems started almost immediately when, at the first dredge location, the contractor ran out of fine white sand and began to deliver a reddish product heavily stained with clay. Critics were quick to jump on the unsightly result. Parley was rather demoralized, but the other three dredge locations all yielded up a plentiful supply of white sand.

Difficulties also attended getting sand to the right place. After the dredging was done, the sand was piled far higher and more steeply than Parley had planned. Nonetheless, he predicted the ceaseless tides would ultimately create a more gently sloping beach.

Not only was he right, but in the course of the readjustment the despised reddish sand turned out to be a scientific boon. As the beach shifted over the ensuing months, it offered valuable insight into the action of ocean currents and waves. A year later it was discovered both several thousand feet to the west of its original deposit site and a thousand feet to the east, proving for the first time that beachfront can travel in multiple directions in short order. From his observations Parley also concluded that Coney would have to be renourished with small amounts of sand every three to four years.

Farley’s tracking of Coney Island’s beach currents with the red sand was the first known use of a technique vital to modern coastal engineering: following tracers. Today these tracers have evolved from Parley’s unwelcome red sand to specially manufactured hues of ground glass and brick dust to irradiated particles and fluorescent materials.

DREDGING ENDED JUST BEFORE THE NEW BOARDWALK finally opened on May 15,1923. Bands, National Guardsmen, and a speech by the governor greeted those who came, and the largely working-class attendees may have felt like officials themselves on that day. Their new public park had been finished with galvanized railing and lights that matched those on Fifth Avenue in haughty Manhattan. The party made New York Times headlines the next day: MANY DANCE ON $4,000,000 STRUCTURE AS FESTIVITIES CONTINUE TO A LATE HOUR .

The boardwalk actually cost about a million dollars to build, with another million dollars spent on the groins and beach fill. The remaining two million had been used for other public costs of the project. It was a sound investment, though, for the city of New York. In a few months property valuations near the boardwalk rose close to five million dollars. The increase in taxable return to the city in one year was sufficient to pay the interest on the whole cost of the project. A side benefit turned out to be that during three unusually severe storm seasons in the following decade, Coney Island property owners escaped the serious damage that other resorts in the area suffered. It was the first evidence that a sandy beach could be an even better damage deterrent than a solid offshore wall. While Parley had predicted these protective powers, it wasn’t until the 1970s that building up sand reserves, as opposed to construction of offshore breakwaters, became the standard for protecting beaches from erosion.

The Coney Island amusement park had its highs and lows during the twentieth century, but it never fell from the public consciousness. Yet the groundbreaking engineering work that went into the beach there quickly retreated from memory. Though its construction inspired a group of Hawaiians to mimic the project in the late 1920s, widening their narrow Waikiki beach into a popular vacation destination, ocean engineers overlooked Coney Island’s example. From the 1930s on, Coney Island Beach appears to have been taken as a fait accompli , a natural wonder. In part this was because it predated the field that could have adopted it as a pioneer. “Coastal engineering” wasn’t formally born until World War II, when the U.S. Navy, looking toward amphibious landings, started training engineers to study waves and currents. In plans for the first postwar artificial beaches, no coastal engineers mentioned the Coney Island example. Instead they started from scratch in the 1950s while engineering some of the most frequented filled shores in the United States: Southern California’s Santa Monica, Newport, Hermosa, and Manhattan beaches.

The fate of Coney Island Beach was not as sunny. It was not refilled every three to four years as Parley had suggested. In fact, the beach got only three reinfusions of sand in its 80 years of existence, in 1941, 1965, and 1995. The last effort, though, has marked a monumental shift for the beach. During the project, spearheaded by the U.S. Army Corps of Engineers and the city of New York, Parley’s original engineering directives were found, and the history and upkeep requirements of the beach are now more fully understood. During the 1995 renourishment effort, Army engineers piled two more feet of sand on the shore than Farley originally called for, and Coney Island Beach today stands at the original 330-foot width that it was built to in 1923.

Ultimately, Coney Island’s sand will wash away again. Let us hope that the next time it is renewed, memories of the groundbreaking revolutionary work that went into it will be renewed too, not buried under loads of newly pumped sand.