Encinitas eyeing soil cement to stabilize Beacon’s Beach

City staff has voiced support for shoring up the bluff at Beacon’s Beach with soil cement — an alternative to a seawall.

However, staffers from the California Coastal Commission have indicated they’re reluctant to back the approach.

Many worry another bluff collapse at Beacon’s could take out the cliff-top parking lot and trail leading to the beach. Yet for years, the city has struggled to find a stabilization solution that appeases different agencies.

City staff made the recommendation based on a study, completed by the engineering firm URS, that analyzed six alternatives for securing Beacon’s, ranging from a seawall to soil cement.

Glenn Pruim, Encinitas’ director of public works and engineering, said the plan calls for placing soil cement — a mixture of cement and sand — at the base of the bluff, also known as the toe. To strengthen the cliff even more, higher parts of the bluff would be rebuilt with natural soil.

“Wave action reaches the toe and weakens the rest of the cliff,” Pruim said, likening the importance of the bluff toe to the foundation of a house.

Unlike a seawall, soil cement can be engineered to erode at roughly the same speed as the cliff, contributing some sediment to the beach. For this reason, the city hopes to win over the coastal commission, which would have to approve a stabilization measure.

The coastal commission has discouraged seawalls. The agency has stated that because they’re fixed structures, they choke off a natural supply of sand over time that acts as a buffer in the face of rising sea levels.

Pruim said given the coastal commission’s stance on seawalls, the soil cement alternative aims to strike a balance between “the engineering and environmental needs.”

However, Pruim said during preliminary talks, coastal commission staffers also expressed concerns with the city’s alternative, namely due to the size of the project and the construction duration. They will expand upon their reasoning in a soon-to-come written statement.

“We don’t think there’s a small project that achieves the objectives, which is to stabilize that hillside,” Pruim said.

The estimated cost of this option: $3.2 million.

The city operates Beacon’s through a 20-year agreement with the state parks department.

Beacon’s took center stage in 2001, when a bluff collapse destroyed part of the trail. Later that year, the California State Parks department awarded a $2.75 million grant to stabilize the area.

In 2009, the city was nearly finished with plans to stabilize Beacon’s with a seawall. But the state parks department said a seawall isn’t consistent with its environmental policies. So, the city later transferred the grant to improvements at Moonlight Beach.

But the question of how to stabilize Beacon’s remains.

Beacon’s has been deemed an “active landslide area.” Signs there warn beachgoers to use the trail at their own risk. Along with erosion issues, a moderate to strong earthquake would trigger a landslide at the spot, according to the URS study.

Mayor Kristin Gaspar said the council identified Beacon’s as a top priority during a planning session last spring and thus directed city staff to look for new stabilization options.

“It’s just a matter of time before that bluff fails, so we have a sense of urgency,” she said.

Gaspar said she’s pleased the state parks department has voiced support for all the alternatives in the URS study.

“That alone is huge, because we haven’t gotten that far with state parks before,” she said.

However, Gaspar said it was unfortunate to hear that coastal commission staff wasn’t receptive to the soil cement option and other alternatives in the URS study. If the commission rules out all the alternatives, Gaspar said the city might want to consider getting out of the Beacon’s operation agreement.

“If someone were to get injured there, the liability is all on us,” Gaspar said.

She added: “If we know this is a safety hazard that we can’t do anything about, that’s a big challenge for the city.”

Deputy Mayor Catherine Blakespear said it’s extremely important the Beacon’s trail continues to offer beach access. She added any stabilization measure should look natural, and the city’s preferred alternative seems to accomplish this.

“I don’t like the idea of having a massive concrete wall,” Blakespear said. “Based on what I’ve seen, that’s not being proposed. So I was happy to see that.”