Planning commission approves amendment to allow engineered "fall‑zone" setbacks for towers

The Florence City Planning Commission voted at its March meeting to approve a text amendment to the city’s Unified Development Ordinance that would let developers measure required setbacks for tower and antenna structures from an engineer‑certified fall zone rather than from the full height of the tower.

The change was requested by Duke Energy so the utility can replace an existing, near‑end‑of‑life guyed tower on North Douglas Street with a newer, self‑supporting structure and still meet setback rules. Planning staff said the amendment would apply to the section of the code that currently requires a separation “equal to 1 foot for each 1 foot in height measured from the property line.”

Why it matters: the existing language effectively requires a 300‑foot setback for a 300‑foot tower; Duke Energy said modern engineered towers are designed to “fold in on themselves” and commonly have much smaller fall zones, so requiring a setback equal to full height can prevent replacing aging infrastructure at its existing footprint.

Planning staff described the requested change: the amended text would allow towers to be separated from a residential district or residential‑use property line by a distance equal to or greater than the tower’s certified fall zone, as measured and certified by a licensed professional engineer, rather than by a strict 1:1 height‑to‑setback ratio. Mr. Lawhon, presenting for staff, told commissioners that “towers have been designed now to fall in on themselves instead of just tipping over,” and that other jurisdictions have adopted similar wording.

Duke Energy representatives said the change is prompted by an aging 299‑foot guyed tower with a lightning rod that the company plans to demolish and replace. “The new tower will support ... Duke Energy’s future technology potential,” said Patrick Bernier, senior project manager for Duke Energy, adding that the company designs towers for long service lives and anticipates 50‑year lifespans. Engineer Caleb Jurgensen of Burns & McDonnell explained the structural approach: by designing lower members so failure points are higher on the structure, “under design conditions ... the tower would fold about itself as opposed to failing at ... the base of the tower,” decreasing the horizontal radius of collapse.

Commissioners asked about specific site impacts, the proximity of nearby houses (staff said a closest property line near the North Douglas site is about 75 feet away), and whether indemnity or other protections exist if a certified design did not perform as expected. Planning staff noted that the ordinance already requires indemnity as part of the special‑exception process and emphasized that a text amendment would not remove existing special‑exception review. Mr. Lawhon reminded the commission that, even if the amendment is approved, the plan for any specific replacement tower would still need to be reviewed and approved as a special exception by the Board of Zoning Appeals.

After questions and public comment from the Duke team, the commission voted to approve the text amendment. The commission’s approval will be forwarded according to the city’s review process; any specific tower plan will still require the special‑exception review and any other applicable permits.

The planning staff report and Duke Energy materials noted sample fall‑zone language used by nearby jurisdictions and argued that the change codifies industry practice for engineered, inward‑folding tower designs.