Bluff stabilization project in Bird Rock gets La Jolla DPR’s approval

Plans to help stabilize a Bird Rock bluff whose decay can be traced to World War II got the La Jolla Development Permit Review Committee’s approval July 19.

The plan is to clear debris out of a crumbling cave and fill it back in to match the surface that surrounds it, using “erodible concrete” that does not have as much cement as its stronger counterpart.

The bluff in question is on the ocean side of the 5300 block of Calumet Avenue, two houses down from Calumet Park.

Applicant representative Walt Crampton, principal engineer at TerraCosta Consulting Group, said the site was used as a military coastal defense base during World War II.

“A small coastal canyon existed in the area and that’s where the gun placements were,” he said.

In the 1950s, some of the debris was discarded into notches in the coastal bluff and the area was covered with gunite, a type of concrete.

More than 60 years later, the surface started to crumble and the debris underneath began to show.

In 2017, Crampton said, the homeowner at 5386 Calumet Ave. asked the city of San Diego to “allow us to stabilize this bluff … with a 35-foot wall to reconstruct the surface, make it more attractive,” Crampton said, but the city denied that application.

By 2020, the erosion had “started to undermine the foundations for the overhead support,” he said.

The following year, additional supports had to be installed for the house because “the vertical support was hanging in space,” Crampton said. The erosion is now visible from the beach and rubble has spilled out.

Working with the city and the California Coastal Commission, a new plan was drafted to fill the deteriorated space with a material that is expected to erode at the same rate as the surrounding bluff.

A photo simulation depicts the repaired bluff, as presented to the La Jolla Development Permit Review Committee.

(Courtesy of Walt Crampton)

Crampton said excavation and debris removal would be done by hand. “We proposed the soil remain as beach fill [in front of the property], but everything else be removed,” he said.

The proposed repair consists of placing “erodible concrete cover over the bluff infill that was placed after the war … and resupporting the foundation” with natural-looking materials intended to blend in with the bluff, he said.

The material has been used on other projects, he added.

“The intent is to have the erodible concrete match the strength of the formation adjacent to it … and the Coastal Commission requires it to be monitored in perpetuity, and if the adjacent natural landform erodes more quickly than the erodible concrete, the erodible concrete has to be eroded back with the natural landform,” Crampton said.

The homeowner would not gain any space from the work on the bluff, he said.

During deliberation by the DPR, trustee Diane Kane said she was “flabbergasted” that houses were permitted to be built above the infill.

Crampton said much of the ground in the area is not in a similar situation, but there is the “occasional gulley” on other area parcels.

Tom Cook of Surfrider Foundation San Diego County raised an issue with fine sediment being placed on the beach and asked that a sediment analysis plan be part of the work.

Trustee Mike Costello said “we don’t like to approve projects that are right on the coast at a first hearing,” but in this case, “if there is a catastrophic failure and if anything goes any further … I don’t want to be responsible for that.”

After a motion passed to make the preliminary review final, a second motion that findings can be made to recommend approval passed 6-0, with a request that the Coastal Commission provide guidance or stipulations on future development on the property.

The DPR’s findings will proceed to the La Jolla Community Planning Association for ratification or further review. LJCPA next meets at 6 p.m. Thursday, Aug. 4, online. Learn more at lajollacpa.org. ◆