Emergency repair of a bluff in La Jolla’s Bird Rock neighborhood is expected to get underway soon and could be the first of many in the area.
An application filed with the city of San Diego proposes a reinforced shotcrete wall with tieback anchors in the face of a coastal bluff at 5322 Calumet Ave. Shotcrete is concrete sprayed at high velocity onto a surface.
Work is expected to begin in the next four to eight weeks.
The project would extend an erodible concrete seawall — which is designed to recede at the same pace as the bluffs around it — that was built after a bluff failure in 2010. The work would not touch the existing wall but would extend it further south.
In 2017, the La Jolla Development Permit Review Committee approved a project to reinforce the lower third of the bluff with erodible concrete. At the time, a geologist said the seawall was expected to last 10 to 20 years.
Applicant Bob Trettin, whose firm is carrying out the new project, said the work would improve safety for the houses above the bluff.
“This section of Calumet has reached a certain stage in time, so it’s not just one house that is of concern,” Trettin said. “For this project, because [bluff erosion] is progressing as rapidly as it is, it achieves that level of imminence that justifies getting something done sooner rather than later. It’s better to get in there and save what you can now.”
When a new structure is built, especially near a bluff, it must have a Factor of Safety of 1.5, meaning it is deemed safe for 75 years and that the structure won’t damage the site. As structures and bluffs age, the Factor of Safety decreases.
Anything less than 1.2 is considered an emergency. Once a property reaches 1.0, it might already have failed “or could fail overnight,” Trettin said.
The property in question is at 1.1 and the proposal is therefore being processed under an emergency permit.
Trettin said efforts would be made to keep the extended seawall consistent and aesthetically pleasing.
“It is going to be sculpted and color-treated to look nice and restore the 1.5 Factor of Safety to the property,” he said. “We want it to be as natural as possible.”
There is no sand on the beach below and the area is not often used for recreational purposes, so Trettin said there will be minimal impact to the public during and after construction.
Because other houses in the area may face a similar fate, Trettin is processing at least one other permit to conduct similar work on Calumet. However, because other properties have not reached an emergency level, those permits will be processed normally and with the recommendation that they go before local planning groups for review.
“We know there is going to be more work going forward,” Trettin said. “One of the problems is when some of these houses were built, they were approved to have a setback 15 feet from the bluff. That would never happen today. Plus, the bluffs have reached a point where if it fails in one area, it is likely to fail in others.” ♦
