Tiburon shoreline project gets closer to launch

A multiyear effort to restore the shoreline at Blackie’s Pasture in Tiburon is advancing.

The Parks, Open Space and Trails Commission received an update on Dec. 16 about the restoration project at Greenwood Beach and Brunini Beach. If all goes well, project leaders hope to break ground in September.

Roger Leventhal, an engineer with the county public works department, said a few final touches are needed before construction can begin. Staff are working to address comments from agencies such as the San Francisco Bay Conservation and Development Commission.

“BCDC comments were the most extensive and really nothing in there that’s going to be a dealbreaker or problematic,” Leventhal said.

Tiburon was awarded $1.4 million from the California Coastal Conservancy last month after getting rejections from other groups. The grant paid for the construction phase of the restoration project.

The project goal is to create a “living” shoreline, instead of a rock wall, to protect against erosion. Living shorelines use sand, rocks, plants and other natural materials to build and stabilize the waterfront. They also create habitat for wildlife, protect against flooding and reduce erosion.

“Living shorelines, things like beaches, are sort of nature’s way of inhibiting shoreline wind and wave erosion, and they move in conjunction with the local wind, wave climate,” Leventhal said. “They rise and fall somewhat with the wave energy at the site.”

A Marin Community Foundation grant funded the concept phase, which started in 2017, and a second grant in 2019 paid for the design phase. In 2021, the final design began and was funded by a San Francisco Bay Restoration Authority grant.

The project will include bringing in sand, gravel, cobble, and boulder material to create the shoreline. Leventhal said the beach had degraded significantly from what it looked like in 2018, mainly because of erosion and a lack of vegetation.

“Essentially all of the sand has been moved off the beach,” Leventhal said. “What was a sandy useful beach for many, many years is now really devoid and eroded.”

The finishing touches on plans should be done by April, with project bidding in May or June. The four- to six-week construction period is projected to end in October.

Chuck Hornbrook, chair of the parks commission, pointed out that a Bay Area coastal cleanup day might fall in the construction period.

“If there’s a moment of serendipity, if you’re moving ahead of schedule, you may want to do some coordination with that, because I was out there walking through the riprap just picking up boat parts,” Hornbrook said.

Leventhal said the grant is valid until 2028, in case the project is held up by permitting or if significant cultural resources are found. He said it should be easy to extend the grant if needed.

Michael Moon, vice chair of the parks commission, asked how far into the water the sand would go. Leventhal said the sand will not go all the way out to the end of the mudflats, but that it could be easier to wade out with a kayak at high tide.

Commissioner Timothy Burr asked what would happen to the riprap — a concrete and rock barrier technique to protect against erosion — at the site. Leventhal said it will be broken up and reused, but a lot will be removed and hauled away.