Bluff retreat near 13th Street

Propping up Del Mar's failing bluffs with piles, plants and seawalls is a temporary fix until the railway can be relocated. But many see the work causing lasting changes.

A skinnier beach. Industrial looking bluffs. A chain link fence. A 1.6-mile wall of armor.

"My heart felt sick," said City Councilmember Tracy Martinez, describing her first reaction to the "after" photos of the engineered bluffs, which appeared "anything but natural."

The San Diego Association of Governments (Sandag) gave an update to the city council last week that did little to change their minds.

A landslide in February came dangerously close to the tracks near 4th Street.

Eventually, in 15 or 20 years, the trains will be moved to safety. The seawalls and beams, removed. Only the vegetation used to slow erosion will remain, a visual remnant of the solution that seemed worse than the problem to many.

"I don't think this region should invest a lot of money trying to piecemeal this, and fight nature," said Hasan Ikhrata, executive director of Sandag. But some view the sweeping fortification as overkill. And securing land from property owners to build a tunnel may extend the timeframe.

"If we're going to get the train off the bluff, we should make sure we're not changing a whole lot of the bluff, and creating things that are removable as quickly as possible like seawalls," said Councilmember Dave Druker.

Some separate the top from the toe of the bluff, arguing it's mainly the top, where irrigation runoff has weakened the soil, that needs safety features.

What bluffs are supposed to look like from 15th to 11th streets in 2050 after tracks have been moved inland.

"Armoring the base of the bluffs from Powerhouse Park to within Torrey Pines State Reserve is sheer madness and an assault on the environment," commented Udo Wahn, an advisory board member at Surfrider Foundation.

A lengthy seawall stretching from 11th to 15th street "will mostly if not entirely erode the beach in that area."

A landslide in February came dangerously close to the tracks near 4th Street, heightening the work's urgency. Conditions are similar to 20 years ago, only now the bluff is eroding closer to the track, said Dave Olson, a representative from Sandag.

The project is meant to protect sections of the railroad until 2050 or whenever the track is relocated. Ikhrata said the agency has tapped 100 million dollars to stabilize bluffs 5 and 6.

Phase 5 has been scheduled, and plans will be submitted to the Coastal Commission later this year. A final design should be ready by next summer, with construction in 2023-2024.

Sandag said they have analyzed each area between 15th and 11th streets to prioritize the seawall location. High priority seawalls will be part of the current phase 5. Low priority seawalls will wait for phase 6, starting in 2025 and lasting about five years.

Laura DeMarco, who opposes North County Transit District's chain link fence along the tracks - part of the multi-agency project - said the $3 million it costs will undermine the $100 million on bluff repairs because the 1400 post holes needed will further erosion.

She pointed out that 4th Street - where February's collapse occurred, was considered low priority before the slide. An independent geotechnical study is needed, she said, to confirm the efficiency of Sandag's plan.

"If this is not addressed in the next five years, I think we're wasting taxpayers' money," Ikhrata replied. "I don't have $10 million dollars sitting around every time a bluff collapses."

People think it will take forever, he said. "I hear that a lot in San Diego. It doesn't have to take forever."

Emergency repairs began in April, installing piling, tiebacks and a grade beam. Rebuilding the fill slope will last through August, and construction of the bluff toewalls through October. Then the slope will be revegetated. A seawall will go at the bottom.

Based on measurements of retreat between 15th and 8th streets, they are planning for six inches of retreat in the northern area, and .4 feet in the southern area.

Olson said the six inches lost per year is at the top - where their focus on the railroad has required a lot of detailed measurements from the tracks to the edge of the bluff.

"If the toe is not retreating while the top is, the seawall at the bottom comes into question," said mayor Terry Gaasterland.

She also questioned the appearance of the dirt layer that will be placed on the bluff, creating a solid smooth slope. "Why is something engineered like that? Why is that deemed better than the natural face of this bluff?"

Olson said it was a problem area for the trackbed stabilization, an over-steepened section that needed to be brought further out.

Vibration from the tracks, which some locals blamed for worsening erosion, is not causing bluff retreat or instability, officials said. Surf, wind erosion, groundwater and natural degrading are all eating away at the bluff.

Design alternatives looked at both 30- and 50-year needs, comparing a baseline of using just piles, ties, and beams to adding a seawall to slow retreat, or a seawall along with stabilizing the bluff surface. The differences were stark.

With no seawall, up to 30 feet of piles would be needed to get to 2050. Add one, and the ground beam can be reduced to about five feet deep.

The weak point: aesthetics. Still, they said, a vegetated bluff is better than one that collapses onto the beach below.