Shipping channels would narrow on Petaluma River to protect bridge

Proposed replacement of buffers around Petaluma River bridge support piers would narrow safe passage zones for shipping.

photo credit: Courtesy of Caltrans

A bridge over the Petaluma River at the Marin/Sonoma County line is getting some reinforcement. And the US Coast Guard is looking for public comment on the plan.

The project would replace an aging collection of structures protecting the footings of the bridge carrying Highway 37 over the Petaluma River, near Black Point.

It would slightly narrow channels for safe passage for boats underneath the bridge.

Carl Hausner, head of the bridge section at the Coast Guard's Eleventh District explained why the work is needed.

"Earlier this year a tug hit the protection system, caused some damage and that's why it needs to be replaced."

Hausner said the wooden objects protecting the bridge approved in 1955 need renewal.

The Coast Guard is involved because of the General Bridge Act of 1946. It requires the agency's approval of the location and plans for bridges over U.S. navigable waters.

Hausner said repairs to the structure have been made, but like most anything exposed to salt water for more than six decades, time has taken its toll.

Bridge protection systems have garnered more attention since the catastrophic failure in March of a major bridge in Baltimore. That's after a container ship collided with a bridge support pier, causing the entire structure to collapse. Hausner said that incident has no bearing on the local initiative.

Preliminary plans for the new protection system would enlarge the safety zone around bridge supports, slightly impinging on space available to sailors.

"When that's complete, that will reduce the horizontal navigational clearance of the bridge by 12 feet, from 140 feet to 128 feet," Hausner said.

In any case, that's not likely to impact anyone, thanks to something just downstream.

"The Black Point railroad bridge restricts the horizontal clearance, I believe the bridge is a hundred feet horizontal clearance, so any vessel that needs to go through the Petaluma River Bridge has to get through the Black Point Bridge, first."

The Coast Guard is accepting comments through August 19th.