RiskHydro is supporting Equinox Environmental on a feasibility study for the Swannanoa Greenway, a nearly seven-mile trail led by Friends and Neighbors of Swannanoa (FANS) and envisioned as part of the Fonta Flora State Trail. The corridor extends from Grovestone Road to Warren Wilson College in Buncombe County, NC. After Hurricane Helene, the team is reconsidering trail alignments and stream crossings in light of changed river conditions. RiskHydro is reviewing the effective flood models and mapping Non-Encroachment Areas. We are also using a post-Helene 2D HEC-RAS model to flag where conditions have shifted and to identify the permitting path for each crossing.
| Location Buncombe County, NC | Client Type Nonprofit |
| Client Friends and Neighbors of Swannanoa (FANS) | Service Area Floodplain Management |
| Project Type Floodplain Permitting & Crossing Feasibility | Partnership Year 2026 |
| Project Status In Progress |
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Hurricane Helene changed conditions along the Swannanoa River and its tributaries, while effective flood models and maps reflect earlier conditions. Several potential crossings are in mapped floodways or Non-Encroachment Areas. These areas are subject to floodplain rules that generally require a no-rise analysis or FEMA approval for a map revision for encroachments to proceed.
Post-Helene bridge replacements and future flood studies may also change effective mapping before the greenway reaches design. That could affect crossing locations, permitting requirements, and the analysis needed for approval.
RiskHydro reviewed potential trail alignments and effective flood models to identify stream crossings and applicable floodplain requirements. We mapped Non-Encroachment Areas, coordinated with Buncombe County staff and North Carolina Emergency Management, and conducted a site visit along the Swannanoa River, North Fork Swannanoa River, Beetree Creek, and other tributaries.
We also obtained and used a post-Helene 2D HEC-RAS model to evaluate where conditions had changed and where future mapping updates could affect permitting. For each crossing, we screened the likely permitting considerations, including whether a no-rise certification or CLOMR may be needed. We identified opportunities to evaluate floodplain benching and other mitigation measures if needed to offset crossing impacts.
Key tasks include:
The study gives FANS and the project team a clear view of each crossing’s floodplain constraints before design starts. The review also highlights where post-Helene changes or future mapping updates may affect crossing decisions, and where mitigation concepts could be worth evaluating.
The feasibility review is helping the team identify where crossing concepts may need refinement and where additional modeling or mitigation may be needed. As the greenway advances, the findings can inform alignment and design decisions and help focus future permitting work.
If your project includes trail crossings or other infrastructure in a regulated floodplain, contact RiskHydro to discuss flood modeling and permitting support.
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