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An aerial view of Coast Highway 101 near Dog Beach in Del Mar. The coastal community has a front-row seat to a growing bluff-erosion problem caused by rising seas, increased rainfall and groundwater. Photo by Marley St. John
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Bluff erosion issues remain ‘at the core’ of Del Mar

DEL MAR — For Del Mar natives, as well as the hundreds of surfers and visitors that traverse its paths, the bluff is a treasured and unique jewel.

But several recent bluff failures between August and December have put residents and officials alike on high alert.

When it comes to the bluffs, Del Martians face two trying, major questions: how to deal with the continuing threat of bluff erosion, and what to do with the 100-plus-year-old train tracks carving a nest into the cliff’s edge.

On Dec.10, a large chunk of the bluff eroded near 10th Street – the latest of several bluff failures since August. Photo by Lexy Brodt

‘At the core’ of Del Mar

As Councilman Dwight Worden has described it, bluff issues are “at the core” of the Del Mar community. To many, the 1.6-mile stretch of sandstone from Torrey Pines State Beach to 15th Street is an icon of the region’s smallest city.

But what remains of the bluff west of the tracks between 8th and 11th Street — where the major recent bluff failures have occurred — is a troubling sight.

Mayor Dave Druker, who has lived in the city for 32 years, said this particular, elevated section of bluff was once as wide as 30 feet, and now, “there’s a spot where it’s inches.”

Although the bluffs have been a looming concern for Del Mar and other North County cities for decades, recent incidents have prompted new problems, and new dialogues.

Adam Young, a researcher at the UC San Diego’s Scripps Institution of Oceanography, estimates the bluffs in Del Mar have been eroding at a long-term average rate of six inches per year, although the recent collapses see “20 years of retreat happening overnight,” Young said.

Young likened the sequence of large erosions to the “aftershock of an earthquake.”

“Multiple sections fell off next to each other,” he said. “When one section came off, the stress was redistributed in the cliff and that caused another area to fall off.”

Young, who studies bluff erosion using remote-sensing techniques, said the primary causes of bluff erosion are the rising waves, rainfall and groundwater.

Soldier piles – NCTD’s go-to for stabilizing the bluffs – jut out near the train tracks at a portion of bluff near 8th Street. The soldier piles are vertical cement columns, 3 feet in diameter and up to 65 feet long. Photo by Lexy Brodt

Under the surface

Residents and city officials primarily blame uphill irrigation for the “weeping” bluffs, which can be seen spilling excess water from their crags and cracks.

When neighbors as far east as Crest Road — Del Mar’s highest point — rinse off their patios or water their gardens, the excess irrigation often becomes groundwater, which makes its way downhill through the city and into the fragile sediment of the bluff.

The North County Transit District, which owns and supervises the train corridor through Del Mar, has attempted to capture this groundwater by installing a number of thin white pipes — called hydro-augers — into the bluff to collect water from the sandstone. The pipes are visible from the beach, jutting out at random intervals from the bluff.

Several of them are surrounded in mid-air with remaining chunks of bluff — evidence of the scale of erosion.

Some believe the pipes are not adequately addressing the issue — or that there are not enough of them to make an impact. They also tend to get clogged with sandstone.

“(The pipes) are definitely taking water out of the cliff, but I don’t think it’s enough,” Young said.

Meanwhile, the bluff is absorbing more water than it can reasonably endure. Councilwoman Terry Gaasterland compared the bluff to a crème brûlée — solid on the surface, and mush just below.

“I would argue that we probably exceeded nature’s ability to absorb the amount of water that Del Mar is putting into the underground drainage system,” she said. “And thus we have this soufflé down there on the bluffs.”

Young asserts that even a more active approach to stopping groundwater is hardly a magic bullet.

“Even if you get rid of the groundwater, the cliff is still going to erode,” he said. “It’s just helping to accelerate the process.”

Future plans for bluff safety

NCTD has been working to stabilize the bluffs since 1998, implementing drainage improvements and installing over 200 soldier piles over the years in order to brace the bluff for future erosion events and sea-level rise.

Soldier piles are concrete pillars up to 65 feet long and 3 feet in diameter, drilled vertically into the bluff.

“They’re just there to stabilize the bluff and minimize the impacts of wind, water, trespassers and sea-level rise,” Stephen Fordham, NCTD’s director of railroad engineering, said.

Their most current effort — Del Mar Bluffs 4 — will aim to increase the number of soldier piles on both sides of the tracks, and to either stabilize or replace several drainage structures. These efforts will help control surface water runoff.

They also plan to reinforce a few bluff-supporting seawalls along the beach.

Various hydro-augers, meant to collect subsurface water from the bluff and divert it to the beach, stick out from above the bluff’s more impermeable, bottom layer. Several of the pipes are damaged, and some have been broken off during recent bluff failures. Photo by Lexy Brodt

Fordham anticipates the project will begin in the late summer of 2019. It will be implemented in partnership with the San Diego Association of Governments, and cost about $3 million.

NCTD and SANDAG are planning more projects between 2019 and 2039, which are estimated to cost up to $90 million and are currently unfunded. They recently applied for a $17.9 million grant to fund further stabilization projects in Del Mar, but were unsuccessful in obtaining it.

Adapting to sea-level rise

Coastal cities are preparing for seven feet in sea-level rise by 2100, and Del Mar is no exception. What does that mean for the bluffs?

The California Coastal Commission — which approves the local coastal programs (LCP) of cities along the California coast — prefers managed retreat as the most formidable long-term option for responding to sea-level rise. Managed retreat involves the government buying private property adjacent to the shoreline and allowing the beach — or bluff — to gradually, and naturally migrate east.

However, in drafting an amendment to their LCP, Del Mar asserted that managed retreat is unfit for the city, largely due to the multi-million-dollar value of beachfront and bluff-adjacent homes.

The city’s Sea-Level Rise Stakeholder-Technical Advisory Committee — which was appointed to study issues of sea-level rise and draft potential “adaptation options” — point to beach nourishment and sand retention as the city’s most viable options for protecting the bluffs from inevitable sea-level rise.

More sand on the beach helps reduce wave “run-up” to the foot of the bluff, minimizing the water’s impact.

Gaasterland, who was formerly chair of the committee, wants to look at “what’s working and what’s failing” locally in order to move forward with best practices.

Gaasterland points to riprap as a prime example — although not a preferred method of local organizations like the Surfrider Foundation, she said the piles of rocks that armor the beach’s edge can help diffuse the force of waves hitting the existing seawalls and bluffs on Del Mar’s shores.

“It’s all local when it comes to beach and bluff reinforcement and protection,” she said.

Crossing legally and safely

When NCTD announced a plan to install fencing along the train track right of way in Del Mar, residents were vehemently opposed.

The fencing plan was the latest in efforts by NCTD to keep the bluff safe. In the past — much to the fury of residents — officers have patrolled the bluff, handing out tickets to those illegally trespassing over the train tracks.

Since January 2014, Del Mar has seen a total of 12 trespasser strikes.

Residents in Del Mar see access to the bluff as a right — many cite a 1909 deed, in which the South Coast Land Company leased bluff top land to what was then the Atchison, Topeka and Santa Fe Railway, with the condition that there be continued public access.

Frank Stonebanks, an active resident who started a Facebook page to share news and updates on bluff access-related issues in Del Mar, said residents were “overwhelmingly opposed” to the fencing plan.

“Nobody supported it,” Stonebanks said. “That was a no-brainer.”

NCTD is planning to hire a consultant to better gauge options for making the tracks safer. Though this quelled residents’ concerns for the time being, fencing has not been crossed out as an option.

It is ultimately the city’s — not NCTD’s — responsibility to establish a safe and legal crossing of the train tracks. There is currently only one — at 15th Street near Powerhouse Park.

The city is in the process of coordinating a feasibility study with SANDAG to study potential crossings. The city is recommending consideration of four locations — at the Torrey Pines State Beach bridge crossing, 8th Street, 11th Street, and at the San Dieguito River.

Residents and officials have different ideas of what will ultimately work for the city, with council members highlighting an at-grade crossing as the most feasible.

A drone photo of Del Mar coastline. Photo by Marley St. John

Looking at the long-term

Gaasterland sees the blufftop community — of which she is a resident — as split into two camps. One group of residents sees NCTD’s measures for reinforcing the bluff as a benefit to their homes, and the other sees the erosion rate as a far-off obstacle.

“They’d rather see the train gone,” she said.

The long-term “vision” of several council members and residents is to ultimately move the tracks inland, and designate the bluff as a public park.

For NCTD, moving the tracks is not at the top of its agenda.

“NCTD’s focus is stabilizing efforts on the bluff to keep the tracks there,” Fordham said. “In the long term, we’re working for stabilizing efforts, in order to maintain the bluffs and keep them stabilized up to 2050.”

NCTD estimates that a new track alignment would cost at least $3 billion — mostly due to the costs and complexity of purchasing right-of-way for the tracks.

Some residents believe delaying this action is detrimental, and that current stabilization efforts are actually doing more harm than good.

“The problem with all of these solutions is they’re short-term, it’s a quick fix, and it damages the long-term stability” said resident and former County Supervisor Pam Slater-Price. “(NCTD) know(s) the real fix … is to move that segment of railroad.”