A “cave” in Sunset Cliffs in Ocean Beach being used by the homeless as a makeshift shelter could be a disaster waiting to happen for nearby condo owners, said a San Diego State University geologist who recently inspected the site.
A hole found in the cliff face being referred to by some as a cave is actually an eroded “void space” in the manmade concrete armoring used to support the cliff face, said SDSU geology professor emeritus Pat Abbott, the author of a standard textbook on natural disasters.
“What I can tell you is there’s been erosion of a pretty heavy concrete mix that was sprayed several inches thick with a hose to armor the cliffs, which has collapsed,” said Abbott. “When you spray this heavy concrete armor on a sea cliff base, that slows down the erosion: It doesn’t stop it.”
The geologist said the primary problem with the earth and other materials there is that they are geologically young and therefore not compacted. “It’s weak material that is not well-bound or cemented together,” he said. “When you rub it with your bare hands it just crumbles. It’s built on very weak, easily erodible sandstone.”
Abbott pointed out rainwater soaks into the ground and gradually works its way down behind the cliff face eventually undermining the soil, as well as the manmade concrete, that has been used to support the cliff.
Abbott added that an inspection of the site revealed “large chunks of broken concrete” that have collapsed, and in collapsing they have “broken water drainage pipes” in the cliff that are leaking water, which is accelerating the erosion.
“A lack of due diligence on the property is accelerating the problem with the collapse of these large chunks of concrete leaving void spaces big enough for people to go inside,” Abbott said.
James Gartland, a marine safety lieutenant for San Diego Lifeguards, said authorities were first alerted to the presence of the so-called cave by nearby condo owners who were concerned that the depression may have been created by someone deliberately digging out the cliff face. He said that’s unlikely.
“They (homeless) may have flattened it out, but there’s no way they dug it out,” Gartland said. “It looks pretty clearly eroded.”
Abbott concurred that homeless people probably didn’t dig out the site, but rather “scooped out the sand and stuff that was inside.”
Gartland noted habitation of that site is illegal under any circumstances.
“It is illegal to sleep on the beach overnight,” he said. “It’s illegal to litter there. And it’s illegal to deface a cliff by carving into it.”
Gartland noted no one to date has been cited in connection with the cave because no one has been actually witnessed using the site. He noted it’s obvious from litter left there that it has been used as a habitation. He added it would also be difficult to bar anyone from going to the site unless you actually posted someone there to keep people out.
He added if offenders are witnessed by authorities using the cave they will be cited.
Abbott said the erosion of that cliff face is probably not a big problem short-term. But he pointed out there is genuinely cause for concern about the future safety of that bluff.
“The homeowners association, or whomever, better get busy and get the permits necessary to come in and repair the erosion damage that has occurred,” Abbott said, adding, “If we get some heavy rains or big storms, that’s likely to accelerate the erosion.”
Nobody needs to be evacuated now or yellow tape put around the site or anything like that. But if the site is not properly maintained, within a generation, those cliffs could be totally destroyed.”
Dave Schwab is a reporter for the San Diego Community Newspaper Group. Contact him at [email protected].