New beach passes winter test with no sand loss
Coastal Science and Engineering reported that its semi-annual survey showed about 4.7 million cubic yards of sand remained in the system out to a depth of 12 feet.
Tim Kana, CS&I president, said that the contour is measured at intervals of about 500 feet along the beach using real-time GPS and sound pulses from a fathometer, with the volume of sand determined by computer calculations.
The first survey in November — after the 10-mile project was finished and after Hurricane Irene — showed that about half of the visible sand had slid into the near-shore system, as intended.
But all of the sand, plus about 100,000 cubic yards remained out to a depth of 12 feet. FEMA guidelines for reimbursement for lost sand after a named storm consider the system to extend to a 19-foot depth.
To save money, engineering of the project called for putting the bulk of the 4.6 million cubic yards on the visible beach and allowing wave action and storms to create a natural slope. That was expected to take a little longer than it did.
The latest survey indicated that 4.9 million cubic yards was in the system out to 19 feet.
“Measurements to -12 show the full nourishment volume remains in the project area and is essentially unchanged since November of 2011,” a summary of the survey said.
The survey also showed that wind and wash-over had pushed about 330,000 cubic yards of sand to the bottom of the dune line since the project was completed.
“This volume will help rebuild the foredune and bury exposed sand bags,” the summary said.
Sand added to the system out to a depth of 24 feet probably came from deeper water and large, long-period waves from offshore storms, it added.
The results were better than expected. Based on historical averages, erosion was expected to take away about 275,000 cubic yards of sand a year.
Property taxes were increased 2 cents per $100 of valuation town-wide and an additional 16 cents on the oceanfront to pay back a loan for $18 million. The other half of the funding for the $36 million project came from the Dare County Shoreline Management Fund.
The county had received authorization to add 1 percent to the occupancy tax to put money back into the fund. County leaders say that now might not be necessary.
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