White Hill slide fix fast-tracked to beat rains

09/21/2017

With winter around the corner, the county Board of Supervisors authorized the Department of Public Works last week to fast-track improvements to a once-wooded section of White Hill that slid twice last winter, cutting off a crucial artery for West Marin residents. The department will award the contract, rather than routing the award through supervisors, in hopes of completing the repair within the next few months.

Currently, concrete barriers are lined against the hillside at the edge of the roadway to support plywood panels to block spills. 

Ernest Klock, the county’s principal civil engineer, said the department hired a geotechnical engineer from the Novato firm Miller Pacific Engineering Group to investigate the site—a steep slope at the intersection of Sir Francis Drake Boulevard and Baywood Canyon Road that sprung two large slides last winter.

Mauricio Loaiza, an employee at the Woodacre Market, said the White Hill closures last winter added “about an hour” to his commute from his home in San Rafael.

The engineer determined the necessary height and depth of the “soldier piles”—or vertical concrete beams—that will form the planned catchment wall. The beams will be drilled 30 feet down and rise roughly 10 feet above ground, supporting wood laggings. 

The department developed the plan for the repair during the spring, but it was only just finalized.

Mr. Klock said construction will occur during daytime hours, with a single lane open for traffic. Work will take place on Saturdays, as well as during the week, to accelerate the completion of the project, and the department will actively notify residents of any delays.

For Woodacre resident Brian Boone, the unavailability of real-time updates during last winter’s road closures was a concern. 

“It was hard to get alerts before leaving the house,” he said. “More than anything, I didn’t know the best information and it seemed like no one did.” 

According to both Mr. Klock and Tom Jordan, the county’s emergency services coordinator, the best method for receiving real-time updates for county-maintained roads is to follow D.P.W. and the local California Highway Patrol on Twitter, at @dpwmarin and @chpmarin.

The White Hill repair—along with three others, including to a section of the Marshall-Petaluma Road—is expected to be complete in the next few months, though Mr. Klock mentioned that contractors are stretched thin by a bevy of slide repair projects in the region.

On the Marshall-Petaluma Road, about two miles east of Highway 1, a retaining wall is planned for where an embankment failed last winter. “It’s out in the boonies, but we did get a complaint from a rancher,” Mr. Klock said. 

The engineer’s estimate for all four improvement projects—the other two are in San Rafael—is $1,650,000. The projects will be funded by the county’s Road and Bridge Rehabilitation Program, though Mr. Klock said the actual costs are unknown until they receive bids. 

The Department of Public Works has other repair projects in their queue, too, including the restoration of part of Sir Francis Drake Boulevard in Samuel P. Taylor State Park where a piece of the road collapsed. Julian Kaelon, a spokesman for the department, said the section is not a high priority but that it will be “supported for the winter months.” 

“We have begun the design process to do a full repair project but, due to the environmental requirements of that area of [state park], the permits we need will not allow us to begin work until next July,” Mr. Kaelon said.