How to Feed a Beach

Sick shorelines make ponderous patients. When one of them begins to waste away under the pounding of winds and waves, engineers usually rush in to order heroic prescriptions--great stone seawalls and jetties reaching offshore to trap the escaping sand before it gets away from the beach. But last week the Army Corps of Engineers was ordering a different treatment for the ailing littoral south of Los Angeles. What this beach needs, say the engineers, is a permanently circulating supply of sand.

Tamed Rivers. Unlike some beaches of the U.S. East Coast, Los Angeles are not nourished by sand washed in from the sea. The Army engineers had to study local history to discover what had gone wrong and decide what needed to be done. When Los Angeles was a Mexican village named The Town of Our Lady the Queen of the Angels, the broad, curving beaches below the San Pedro peninsula took care of themselves. The waves of the Pacific beating diagonally on the shore made the sand move southeastward in a low, powerful stream. But the beaches always recovered the loss, because three turbulent rivers plunging down from the mountains supplied fresh sand.

When the village grew into a great city, the three rivers, the Los Angeles, the San Gabriel and the Santa Ana, were gradually diverted, dammed, and made to run, when they ran at all, in floodproof concrete channels. By the 1940s, they were completely tamed; they brought hardly a grain of fresh sand to the shore. The beaches, now lined with parks and cottages, were already in serious trouble. In 1947, when waves had swept across the skinny beach at Surfside and battered the shoreward cottages, Army dredges pumped 1,000,000 cu. yds. of sand from the bottom of a Navy channel at nearby Anaheim Bay to form a protective barrier. But the cure did not last. In spite of another dose of sand provided by the Navy, the beaches continued to waste away. The damage reached twelve miles southeast to Newport Beach which boasts some of the most expensive shore front property in the U.S. Early this month storm waves smashed 75 houses at Surfside and every high tide threatened more damage.

Before this, the engineers realized that they were dealing with a one-way stream of sand which was no longer replenished by the three tamed rivers. They estimated that 200,000 cu. yds. of sand moved along the shore each year and plunged into a deep underwater canyon off Newport Beach, where wave action could not reach it. And they were certain that if nothing were done, the sand stream would eventually carry away all the finest beaches south of Los Angeles. Pumping sand from the bottom of Anaheim Bay was no answer; there simply was not enough sand there.

Sand Circuit. The engineers have worked out an ingenious solution. The first move, says Engineer William J. Herron Jr., will be to dredge from Anaheim Bay and any other available source 3,000,000 cu. yds. of sand to spread over the beaches where the sand stream is born.

Like so much other sand before it, this new supply will flow slowly toward the hungry Newport canyon, where ordinarily it would be lost forever. But before the fresh sand arrives at that place of no return, the engineers will have built a 2,600 ft. breakwater paralleling the shore, just short of the canyon. By intercepting the waves, the breakwater will create a stillwater trap where the sand will settle before it gets lost in the canyon. In about five years, Herron figures, Surfside Beach will be threatened again. But then sand will be available in the breakwater trap to be pumped or dredged to replenish its beach. The process will be repeated over the years, and sand flowing from beach to trap and back again should keep Greater Los Angeles in bathing grounds indefinitely.

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