pilings to protect them from scour. The rock fill from the tidal channel to the north wing spit
was completed in August 1956.
On 4 September, the bottom of the channel was armored for the final closure operation. The
rock was dumped evenly along the entire 800-ft width of the tidal channel to ensure that a
constant elevation was maintained. Closure operations were shifted back and forth from the
seaward and bayward sides until closure was made on 13 September. After closure, the
superstructure and bracing of the trestle were removed, and the rock fill was completed to full
grade. Final dressing of the rock fill was completed on 16 November.
With the breach closed, sand that had previously been transported into the bay was trapped by
the breakwater, and sand accreted quickly on the seaward side of the fill. Accretion on the
bayward side stopped, and tidal flow through the Federal navigation channel increased.
Construction engineers concluded that the tidal current velocity encountered during the closure
operation was too great to close the breach with only a sand fill. They also believed that if the
breach would have been closed by end-dumping a rock fill, the concentration of tidal flow would
have scoured large volumes of sand that would have been expensive to fill. The key to a
successful final closure was maintaining the top of the closure fill at an approximate constant
elevation.
Buxton Inlet, North Carolina. On 7 March 1962, the "Ash Wednesday Storm" breached the
North Carolina Outer Banks 2 miles north of the town of Buxton. The breach, called Buxton
Inlet, destroyed the coastal road, isolating the residents of Avon from Buxton where children
attended school. The breach was surveyed in June 1962 and had a width of about 700 ft and
maximum depth of 8 ft at that time. The breach occurred on National Park Service property, and
the U.S. Army Engineer District, Wilmington, was requested to close the breach and restore the
barrier beach to its approximate pre-storm condition. A complete discussion of the breach
closure operation is given in Wilmington District (1963).
The breach closure plan called for pumping sand with a single 1,160-hp, 16-inch hydraulic
pipeline dredge pumping from both sides of the breach. Pumping from both sides was
accomplished with a submerged pipeline that extended from the dredge at the north breach bank
across the inner bar to the south bank. A total of 49,500 cu yd of sand was pumped into the
breach from 22 November to 26 November 1962, when a storm struck and grounded the dredge.
The submerged pipeline was lost in the storm. A survey after the storm showed that the breach
had widened to approximately 1,500 ft with a maximum depth of 11 ft. Given the increased size
in the breach, it was decided that it would be necessary to employ a second 1,600-hp, 16-inch
pipeline dredge to fill the breach. Each dredge was capable of pumping about 9,000 cu yd of
sand per day.
The original 1,160 hp dredge resumed operations on 27 December 1962. Sand pumped after the
storm was deposited on the north bank of the breach. The south bank appeared to erode at nearly
the same pace as the accretion on the north bank. To mitigate the south bank erosion, local
interests dumped broken culverts, automobiles, and other non-engineered materials in late
January and early February of 1963 (Figure 5). Approximately 486,000 cu yd of sand was
pumped by the single dredge over a 55-day period, but it could not close the breach. As the
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