After considering a few options, NCDOT has settled on building a massive concrete retaining wall to protect Interstate 40 from the raging waters of the Pigeon River near the border with Tennessee. And by massive, think Hoover Dam in scale. This concrete wall will be 5 miles long, 30-70 feet tall, and 30 feet thick. No one wants to be the person who gets in the way of reopening an important highway, but before we sink a billion dollars into the project, I feel like the public needs to know there are some serious issues with the current wall plan.
The biggest flaw is that NCDOT isn’t replacing the creek culverts that pass under I-40 (and thus will need to pass through the wall). These creek culverts survived Helene, so why fix them? Well, it turns out the local rainfall in the Pigeon River Gorge area was actually pretty modest (only 6-10 inches) compared to what Helene dumped upstream (24 inches-plus). So while the river itself was a monster, the side creeks were relatively tame. Which means that we’re about to build a billion-dollar wall on top of rusty old pipes that date back to the 1960s or before. Replacing and significantly upsizing those creek culverts would require time and money, and even some additional closures of the highway. On the other hand, rebuilding the wall in just a decade or two when the increasingly warm Gulf of Mexico sends another hurricane our way would be unthinkably expensive and wasteful.
Plus, upsizing the culverts would address the second big issue, which is that the massive retaining wall will cut off habitat connectivity for wildlife across one of the more important wildlife corridors on the east coast. I-40 in the Pigeon River Gorge snakes its way right between Great Smoky Mountains National Park and Pisgah National Forest (and all of the Appalachian forests to the north)…