Shoring up shaky bluffs at beach 

City officials have put together a strategy to immediately tackle the erosion that threatens the bluffs lining Great Highway, including nailing down a buried seawall at the most critical spots.

The plan, which needs to be approved by the California Coastal Commission, spells out the increasing risks of erosion during the next decade and outlines possible solutions, which include constructing a buried seawall or concrete pilings and rock walls that would cost as much as $1 million.

The analysis identified three critical spots that are most at risk in the face of this season’s El Niño storms, which could cause more erosion within the next two years, threatening beaches, trails and a 14-foot, 10-million-gallon waste-water pipe.

The most urgent area is the stretch located north of the San Francisco Zoo entrance, south of the intersection of Sloat Boulevard and Great Highway, where the bluffs have eroded 70 feet in the past decade, said Frank Filice, manager of capital planning for the Department of Public Works.

In one spot, a guardrail has fallen into the ocean.

There’s a 100 percent chance the bluffs in that area will erode in the next two years, reaching the roadway, unless The City builds a buried seawall or concrete piling this winter, Filice said.

“It’s a critical area,” he said. “There is a need to have action immediately.”

However, not everyone agrees with that analysis. Dean LaTourrette, executive director of the Save the Waves Coalition, said there’s no real evidence that these hard structures — seawalls and concrete piles — are necessary at this point.

“It’s just throwing rocks at the ocean,” LaTourrette said. “Other than addressing a real, true emergency, it’s a waste of taxpayer money.”

Earlier this year, the Department of Public Works built a controversial 425-foot wall to keep the powerful waves at bay after officials declared an emergency in January when the cliffs retreated all the way to the roadway.

Since then, city officials have scrambled to deal with the erosion in the short term, looking to buy some time while they devise a more permanent solution.

Bill McLaughlin, a committee member with the nonprofit environmental organization Surfrider, said the new report was too vague. It left his organization in the dark about concrete plans for managing eroding bluffs.

“We can’t figure out what they are committed to building,” McLaughlin said.

 

Closure of coastline route presents safety concern


The continued closure of the Great Highway could have a devastating effect in the event of an emergency, according to a traffic report released last week.

The Department of Public Works is using that argument as leverage to immediately start work to reopen the shuttered roadway nine months after it was closed due to winter storms and eroding bluffs.

On Aug. 30, crews will begin installing new drainage while reconfiguring the roadway to move it east 30 feet away from where it runs now, with plans to reopen it by Oct. 15, said Frank Filice, manager of capital planning for Public Works.

Southbound traffic along Great Highway between Sloat and Skyline boulevards has been closed since Jan. 18, when city officials declared a state of emergency after inches of rain ate away at the sand at its base, threatening its stability.

Since then, drivers have been detoured, causing major traffic backups and congestion at various intersections along Sloat and Skyline boulevards, Filice said.

But the traffic report shows that the detour route is not accommodating the area’s traffic demands. In fact, congestion has increased threefold along the intersection of Great Highway and Skyline Boulevard, with average daily traffic counts rising from 4,000 to 12,969, according to the report.

In addition, The City has lost one of its main emergency routes, forcing public safety vehicles to use the congested detours.
“We have had a number of phone calls about traffic concerns from the detours, so we need to re-establish it as well as maintain our emergency road system,” Filice said.


Mending the cliffs


The most critical spot of the eroding Ocean Beach bluffs is located north of the San Francisco Zoo entrance, south of Sloat Boulevard and Great Highway. Some ways it could be fixed include:

$600,000: A buried seawall
$520,000: Using rocks for erosion control (rock revetment)
$1 million: Concrete piles (tangent pile wall)

Source: Department of Public Works

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Erin Sherbert

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Thursday, Dec 18, 2014

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