Otter Rock Tower Replacement on the Oregon Coast

Location: Otter Rock, Oregon coast
Client: Silke Communications (owner of the tower)
Partners: Valmont (tower supplier and designer)
Year: 2015
Size/scale: New 150-foot tower built around the existing tower
JBE services: Foundation system design for the new tower and the existing tower, and the permit drawings. The tower itself was supplied and designed by Valmont.
Sector: Towers & Telecom

The original Otter Rock communications tower in coastal fog before its replacement

The challenge

The tower at Otter Rock needed replacing. The usual approach is to take the old tower down and put a new one up in its place. That wasn’t an option here. The antennas on the existing tower were in use, and they couldn’t go off the air for the time it would take to demolish the old tower and build a new one.

What we did

We worked with Silke Communications on a different approach: build the new tower around the existing one. Valmont supplied the new 150-foot tower, and we designed the foundation system for the new tower and the existing one. The new structure is an “exo-tower”, a skeleton that surrounds the old tower while the old tower keeps working inside it.

The new tower brought new loads down to the foundation, so we upgraded the foundation to resist them. We widened the existing 30-foot-square mat foundation to 42 feet and added a new 12-inch reinforced layer doweled into it. Once the new tower was up, the antennas were shut down briefly and moved from the old tower to the new one.