Experts Call for Long-term Fix for Beach Erosion
By Thomas K. Pendergast
Now that a southbound lane of the Great Highway has reopened near the SF Zoo, officials at the California Coastal Commission (CCC) are considering a plan to shore up the bluff under it before the next big storm surge hits and undermines the important highway once again.
Last December and January storm waves tore a huge chunk off the bluffs south of Sloat Boulevard, enough to cause the right lane in the southbound direction to fall down onto the beach, forcing closure of the Great Highway to southbound traffic.
Road crews moved the southbound lane further away from the bluff's edge by reducing the middle barrier between the northbound and southbound lanes to about five feet, using the extra space for one southbound lane while keeping two lanes going in the northbound direction.
A huge pile of rocks and chunks of concrete were placed on the beach at the "toe" of the bluff as a stop-gap measure to protect against further erosion but this is seen as only a temporary fix.
Frank Filice, manager of Capital Planning for the SF Department of Public Works, said his department provided a technical analysis which identified options and recommended there be additional repairs to the face of the bluff, then sent it to the California Coastal Commission for review on Sept. 16.
The situation is bureaucratically complicated because at least three different government entities, the CCC, National Park Service and the City, all have some jurisdiction over either the affected property or land adjacent to it.
Filice said his department will not recommend changing the roadway from its present form and position, wherein two lanes go north but the two lanes going south merge into one at the site of the bluff erosion, then fan back out to two lanes again. He said a traffic volume study conducted by that department determined that this road configuration was adequate to handle the southbound traffic flow, even during the rush hours.
"Two lanes turn into one, then go back to two," said Filice. "Based on that study, we didn't feel the need to maintain two lanes in order to maintain traffic flow. There's enough length on the narrowing lanes to handle the merge and then it fans out from one to two lanes."
Shoring up the bluff, however, is a different matter.
The report sent to the CCC recommends that at the southern tip of the affected area, the rocks already there should be relocated somewhat. North of that, however, at the two most severely eroded areas, stronger measures are needed, such as a low-height concrete-and-steel sea wall or perhaps a tangent pile wall.
A tangent pile wall is a combination of concrete pillars that are cast in place, with a concrete cap placed over it and often with a skeleton of rebar running through it.
Critics, however, say solutions like these are still just short-term solutions which will only delay the erosion of this area; so long-term planning is needed to really deal with the problem.
"In general the City has done a poor job in planning for coastal erosion," said Dean LaTourrette, director of the Save the Waves Coalition. "That area south of Sloat wants to erode, no matter what they do with band-aid solutions to stop it."
LaTourrette said over the past dozen years or so, there has been at least three emergencies involving erosion as a threat to the highway and dumping rocks has been the only solution they have come up with so far, which does not work in the long run.
"If you stop the natural erosion in one area then it exacerbates erosion in other areas," he explained. "It will redirect that (wave) energy to the nearest side of the rocks, which will increase erosion there.
"The current bluff collapse happened just south of areas where they'd previously dropped rocks. This is an archaic means to slow erosion," LaTourrette said.
Aside from the possible threat that further erosion to the north might pose to the Snowy Plover or the Bank Swallow, both of the birds being protected species with breeding grounds just north of the bluffs, there is a distinctly grotesque scenario waiting to happen should those bluffs continue to erode inland, one that moving a highway around won't solve.
"The biggest issue is there's a tunnel that runs near there, the Lake Merced sewer tunnel," said LaTourrette. "No one wants a sewer tunnel to be breached. That certainly is a big concern. You've got to be concerned about relocating critical infrastructure otherwise you're just throwing rocks at the ocean. They've been spending a lot of money for short-term solutions that are environmentally damaging and don't solve the problem. Why are they treating the south end of Ocean Beach like a poor second cousin?"
Benjamin Grant agrees that a short-term fix will only delay saying good-bye to the bluffs. As a project manager at San Francisco Planning and Urban Research (SPUR), his organization is working to "try and take the long view.
"The problem is episodic, in that nothing will happen for a period of time and then suddenly there's a storm and the DPW has to deal it immediately. There's no long-term framework for dealing with the issue," he said.
Grant said his group is acting as a facilitator to try and help coordinate the various stakeholders, agencies and government entities that are involved in dealing with the problem.
"The erosion issue is very immediate and very present, so a lot of the conversation keeps going back to that. We've got to create a long-term framework so that we're not stuck in that mode," Grant said.
SPUR is now involved in a 16-month project that's engaging stakeholders, experts, landscape architects and civil engineers to come up with a long-term plan for Ocean Beach.
"We want to be thoughtful to create a policy that ... leaves as much flexibility as possible for future decisions," he said.