The Wrightsville Beach Board of Aldermen voted to allow coastal engineering firm Applied Technology and Management (ATM) to proceed with the initial phase of challenging FEMA’s preliminary floodplain designations for Harbor Island.
Since the maps were released showing illogically high-risk flood zones for much of Harbor Island, the board has been carefully and thoroughly exploring the possibility of an appeal.
In October, coastal research specialist Spencer Rogers presented the board with an explanation of the new flood zone designations. Then, in December, the aldermen met with representatives from the state floodplain mapping program to gain a further understanding of the models used to create the designations and therefore determine possible methods for appealing them.
Thursday, Jan. 8, the board met with representatives from ATM to hear its plan for a Phase 1 review, during which the firm would identify any areas of FEMA’s study that could be tested and challenged to affect the designation for Harbor Island. The first phase would cost $24,700 from the town’s reserve fund.
Senior coastal engineer Fran Way said the firm would determine the accuracy of FEMA’s LIDAR elevation data by comparing the points to elevation certificates on file. Using the new data it would then re-run FEMA’s Wave Height Analysis for Flood Insurance Studies (WHAFIS) model.
Way described how the WHAFIS model currently predicted wave action at Wrightsville Beach, with the swells diminishing while passing over the beach strand and then regenerating in Banks Channel.
“They’re saying [the waves are] coming across Wrightsville, breaking, and you get the AE, and then it just hits these lower areas where it’s able to regenerate just enough to get back to the VE,” he said. “But we’ll look at it pretty closely because it doesn’t seem to pass the walking around test.”
Way said FEMA runs the WHAFIS model on a strip of land, or transect, it feels is representative of the area. But the WHAFIS model is extremely sensitive to topography, he added, so ATM could run the model on a new strip of land, even just 50 feet to the north or south, to affect the flood zone designations.
FEMA didn’t have the luxury of being so selective and precise during the mapping process, Way pointed out, which sometimes affected the accuracy of the results.
“When these guys are mapping, they’re mapping entire areas,” he said, “whereas we’re really going to focus on this one little area, and a lot of times when we do that we can find areas where they didn’t spend as much time.”
Town manager Tim Owens said the only area re-examined would be Harbor Island, so designations for the rest of the town would not be affected. Furthermore, if at any point ATM’s findings began to indicate the town wouldn’t win an appeal, the process could be halted.
“From what we heard today, I don’t see how we can not do it,” Alderman Hank Miller said.
Following Phase 1, ATM will provide findings and recommendation to the town as to whether to proceed with Phase 2, a final analysis and appeal submittal.
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