Alternative solutions to Isle of Palms’ beach erosion issues were presented at a Beach Management Ad Hoc Committee meeting on Oct. 10. Chris Creed, P.E., a coastal engineer with Foth | Olsen, shared the firm’s findings with the committee.
Foth | Olsen is a coastal and marine engineering firm with more than four decades of experience delivering shoreline and resilience projects across the southeastern United States and other coastal regions worldwide. The City of Isle of Palms, which has been working with another engineering firm, asked Foth | Olsen for a second opinion. Creed has worked on Hilton Head Island’s beach management plans for three decades.
Creed said there are two major areas of Isle of Palms beach erosion that need focus — the north end near Dewees Inlet and the south end at Breach Inlet. Adding sand to the beaches through nourishment cycles has not been enough. To create a long-term plan that successfully reduces the amount of sand needed for future renourishment, the city should take a more proactive approach instead of simply reacting to erosion events.
North End Issues and Solutions
The north end of the island near Dewees has shoal-shifting events that negatively affect the coastline. Among Creed’s recommendations, his primary focus for this area is a proposed “sand trap” shoal management plan. In this plan, the sand shoal that moves in naturally would be dredged — not deeply, but enough to level out the seabed. The dredged sand would then be used for local beach nourishment, and the offshore “sand trap” would allow another shoal to move in. When it does, the process would be repeated, providing a sustainable and local source of sand.
“Let’s address the problem before it gets to you,” Creed said. “Is there a way we can manage these events away from your shoreline so that you eliminate the localized problem as the shoal approaches, but also provide a sand source?”
Creed believes the shoal events can be mitigated before they become a problem. This “sand trap” mitigation plan — a shallow-water-based dredge — would require further studies before moving forward. However, the dredging could take place during the city’s next beach renourishment project in the next year or so. Although Creed admitted the plan is conceptual, he said “the approach is sound.”
While the “sand trap” plan would be more proactive, Creed also offered an alternative that would “establish a line of defense.” He suggested solid structures about 100 feet in length, called breakwaters, that would run parallel to the shoreline. Creed said this technique has been successful on many shorelines and shared images of Port Royal Sound on Hilton Head Island, where the breakwater solution has led to beach growth over time.
South End Issues and Solutions
Creed said the south end of Isle of Palms experienced long-term accretion of sand until 2010–11. At that point, the area began to erode, and the rate of erosion has accelerated recently. He added that the city’s previous strategy — hoping the beach would naturally return to its original condition — was unlikely and overly optimistic.
To restore the beach to historical conditions and manage the current sand loss rate, Creed recommended a tandem approach using a terminal groin and detached breakwater. He shared an example of a similar successful project on the south side of Amelia Island, Florida.
According to Creed, aerial images indicate a change in the tidal prism — the amount of water that flows in and out of an inlet during a tidal cycle — near the Intracoastal Waterway and Breach Inlet. Creed believes an increased inlet prism may be contributing to the sand loss and changes at Breach Inlet. More studies are needed to confirm these findings.
Conclusion and Challenges
Creed said sand placement alone is not an effective long-term strategy. The city could reduce the cost of sand over time by managing sand sources and identifying closer, better-matched sand to the existing beach grain size. He described the practice of sand scraping as “death by a thousand cuts” — too slow and inefficient.
For long-term mitigation, a proactive approach should replace the city’s current reactive strategy toward shoal events and beach erosion. In South Carolina, the regulatory process can be challenging, but Creed believes Isle of Palms should begin earlier conversations with the state about demonstrated need, using research data and forecasting. Ultimately, he said, the city should be planning several years ahead.
Next Steps
Creed recommended that the city pursue proactive shoal management on the north end instead of a structure-based solution and continue its sand renourishment plan on the south end while preparing for a long-term structural approach.
Until the city has a plan in place to control erosion, Creed said residents should be allowed to protect their property. The city currently permits the use of large sandbags, but Creed suggested other temporary measures such as Geotubes, which last about five years. When asked whether he had seen other municipalities with an ordinance similar to Isle of Palms’ rule prohibiting homeowners from building erosion control structures within 250 feet of the ocean, Creed said he had not.
Members of the ad hoc committee agreed that the city’s current approach is “drifting.” They voted to engage Foth | Olsen to identify alternatives for long-term solutions, develop proposed plans and timelines, and provide regulatory assistance.