The Curve of History
By Kip Tabb –
The Rodanthe S Curves will be a page in history.
The waves that create some of the cleanest breaks and best barrels on the Outer Banks, and arguably on the East Coast, are the very forces that are rolling the shoreline back 10’ and 15’ per year.
In discussions with NCDOT officials, US Fish and Wildlife (USFW) personnel, and shoreline geologists who have studied it, there is near universal agreement this is a stretch of beach that cannot be saved. NCDOT is moving quickly to find a permanent solution that will keep NC 12 a viable connection to Hatteras Island.
The road, however, is only part of the story. In our coverage, we will explain why this particular stretch of beach is so dynamic, and we will also examine alternatives suggested by Dr. Stanley Riggs of ECU—considered one of the pre-eminent shoreline geologists of our times. Dr. Riggs has stated on a number of occasions that given the transient nature of our shoreline, a ferry system in conjunction with other modes of transportation may be the only practical solution for Hatteras Island.
A Day at the Breach
Our story starts with NCDOT plans for a permanent remedy for the S curves,
It is a stretch of road that consistently floods, sealing off Hatteras Island from the rest of the world. Generally after flooding, the road is impassable for two to three days, the roadbed intact but covered by sand and water.
The breach caused by Irene, though, was the worst that has been recorded, and shoreline geologists and highway engineers agree it is a harbinger of things to come. Caused by soundside flooding, it was unique in the severity of the damage and the direction of the destructive force, but the assault on the S curves can only have one outcome.
“It is a stretch of road that cannot be saved, not without a tremendous amount of engineering and monetary resources,” Pablo Hernandez, NCDOT Assistant Resident Engineer for Eastern North Carolina, says.
Even before Irene washed the road out, NCDOT highway engineers knew they would have to replace sections of the highway on Pea Island. The Final Environmental Impact Statement (FEIS) issued for the Bonner Bridge project, noted the hotspots–areas of extraordinarily high shoreline retreat–along NC12. The original timeline in the FEIS assumed planners would have a chance to assess the best way to maintain the road at the S curves. Irene clarified the urgency of the situation. The four or five year window highway engineers thought they had has evaporated. “Irene accelerated the process for replacing the road,” Beth Smyre, Project Planning Engineer for NCDOT, says.
Pushed by Governor Perdue and already having preliminary plans on the books, NCDOT moved quickly to a public presentation of plans for preserving a highway link with Hatteras Island. In December of last year, highway engineers introduced a series of options for a permanent solution.
The possible remedies clarify that there is no perfect answer.
If the shoreline could be stabilized, there would be no need to move the road, and beach nourishment has been successful in preserving and stabilizing beaches in a number of locations.
Pea Island is administered by USFW and at the December public hearing, concerns were raised about whether a beach nourishment project could be permitted. Dennis Stewart, Wildlife Biologist for Alligator River and Pea Island National Wildlife Refuge, notes that under certain circumstances, USFW will consider beach nourishment to preserve a transportation link. “We’ve been nourishing the beach at the old Oregon Inlet Lifesaving Station with the dredge spoils from the inlet,” he says. “If the circumstances are right, we will consider a nourishment project.”
However, according to a number people of familiar with the studies that have been done on the area, the S curves are not a candidate for beach nourishment. There is no ready source of suitable sand and the dynamic forces at work would make the process prohibitively expensive with uncertain results.
It is possible to move the roadbed further to the west, but that simply puts off finding a permanent answer to an ongoing problem. Originally a straight north/south road, SR12 as it traverses Pea Island has accumulated a number of bends over the years, invariably to the west, as engineers respond to the ocean’s encroachment.
There are other problems with moving the road to the west. NCDOT is granted a 100’ wide right-of-way through Pea Island by USFW for the purposes of a transportation corridor. If the road was moved further to the west, away from the ocean, a new right of way would have to be granted, and no one is certain if that right of way could be permitted.
Another possibility, creating a seven mile bridge in Pamlico Sound, was examined. The bridge would begin at the newly formed inlet at what was the Pea Island maintenance sheds and make landfall on the south end in Rodanthe. NCDOT quickly concluded that there was no way to fund that option.
A scenario that was presented and appears to have the least number of obstacles to moving forward, is to bridge the corridor from the new inlet, at the Pea Island maintenance sheds, to Rodanthe.
Highway engineers indicated the project is possible and may be the only solution in the long run. As currently envisioned, the bridge would be 23’ above sea level–although one of the engineers at the hearing indicated that is a preliminary figure and more tests on wave heights would have to be done to determine a final figure.
Because it would be constructed in the existing right of way, no new right of way permits would have to be issued by USFW. Additionally, although this is a preliminary assessment, it is possible that if constructed in an existing roadbed that had been damaged in a natural disaster, FEMA funds may be available.
It seems a remarkable concept and highway engineers are aware that extraordinary forces will be at work. “A bridge can be engineered to be in the surf zone,” Hernandez says. “It’s in a very high energy zone. And we have to plan for storm events.”
Surf zone construction is already a part of Outer Banks life–the piers that line the beach from Duck to Avon are very much examples of surf zone construction. But a fishing pier is not engineered to handle a 40 ton truck. “Bridges are designed for truck traffic and loads,” Hernandez says.
Still in their initial phase, the concepts being developed visualize a long-term solution to an ongoing problem. “If we’re going to build a bridge,” Hernandez says. “We’re going to build it to have a 75 to 100 year lifespan. It’s not ideal, but it could be done.”