Sometimes There’s No Other Choice to Siting a Tower in a Floodplain

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No one really wants to site a cell tower in a floodplain. It adds to the construction and maintenance costs, says Jimmy Miller, president of Gulfport, MS-based MillerCo. The ideal choice is to site a tower on “high ground, next to a highway, with dark fiber nearby,” says Miller, who’s also on the board of directors of the National Association of Tower Erectors. He spoke Friday during the FCC’s annual workshop on the environmental compliance and historic preservation review process required for the construction of wireless communications facilities.

He discussed what to consider when siting in a floodplain, when there is no other good choice, to obtain the best RF signal strength for the carrier’s network. Nearby airports, as well as local zoning codes and signal coverage factor into such siting. Soil conditions, wind loading, and ice loading are also factors to be considered when building a tower and associated facilities in an area near a river or coastal area.

As hurricanes have become more frequent and stronger, local zoning codes and FEMA requirements now call for cell tower sites in or near a floodplain to be higher than they used to be. Miller discussed a site his company built in Waveland, MS, that’s much lower to the ground than a newer one he built about 200 yards away in 1990. The new tower, built for a utility, is about 480 feet tall.  

Before Hurricane Katrina, the equipment for a multi-tenant site next to a river in Biloxi, MS, was about two feet off the ground. “Every carrier in the nation” was on the site, said Miller. The equipment was placed “much higher” when the site was re-built. A more modern site in a Louisiana Bayou was placed 15 to 20 feet off the ground.

Much of the time, the tower is built on a foundation at ground level, but everything else is elevated. That includes the electrical power service entrance, carrier equipment and backhaul, backup power source and backup power fuel. Lighting controls are often elevated as well. “Minimal elevation is determined by FEMA maps,” though most elevations “exceed” those recommendations, said Miller.

Carrier network topology is different now than during Katrina, when “South Mississippi became a communications island,” with little service, Miller said. Now, networks are designed with multiple redundancy to carry calls and data along various paths, so the loss of a tower site doesn’t devastate an entire area. Comments? Email us.

By Leslie Stimson, Inside Towers Washington Bureau Chief

October 15, 2018

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