CARLSBAD — The city is preparing for sea-level rise by partnering with a prominent local research organization to perform a realignment study on a portion of Carlsbad Boulevard to help mitigate any future structural damage due to climate change.
The Carlsbad City Council approved a $498,075 grant during its Sept. 14 meeting from the California State Coastal Conservancy for Scripps Institute of Oceanography to conduct studies on sea-level rise and how to move the road’s southbound lane eastward, away from the ocean, between Palomar Airport Road and Island Way.
The city will begin its public outreach to residents and businesses in January.
The South Carlsbad Boulevard Climate Adaptation Project marks the first major review of the city’s infrastructure in relation to sea-level rise, according to Mike Grim, the city’s senior program manager. (Grim retired on Oct. 14 after speaking with The Coast News.)
The study is expected to take about 16 months and return to the council in Feb. 2023, according to Grim.
“It’s doing a little more detailed analysis of bluff erosion and flooding impacts would be due to sea-level rise or extreme storms,” Grim said. “And then analyzing the realignment of the boulevard and then what to do with that intervening space. We are going to move that as far east as we can.”
From the study’s starting point at Palomar Airport Road, Carlsbad Boulevard drops down near sea level before ramping up to the north end of South Carlsbad State Beach campground. The northbound and southbound lanes are separated by a natural landscape buffer.
A stretch of the roadway has sustained damage on two previous occasions. In 2015, massive waves eroded 300 to 400 feet of the bluff near the Encinas Creek Bridge and Island Way, forcing months of construction and the installation of two- and four-ton boulders to mitigate erosion.
In 2010, a winter storm south of the bridge and the relocation of a sewer line and lift station, according to a Coast News story.
Grim said the northbound lanes would remain and southbound lanes could line up closer. In addition, the project must be consistent with the city’s General Plan mobility element and complete streets with multi-modal components.
Grime said the plan includes a multi-purpose trail, improved coastal access and parking, with open-space opportunities from Palomar Airport Road to Batiquitos Lagoon.
A preliminary analysis has been conducted with some engineering, Grim said, and now a more robust public outreach program will be started. The public will be asked about general preferences in the overall vision and more detailed aspects such as sidewalks and roundabouts or traffic signals.
Those components will return to the council in summer 2022, while the final report from Scripps is due to the Coastal Conservancy and the council in 2023, Grim said.
Jennifer Fields, the project manager, and Taylor Samuelson, public information officer, both with the Coastal Conservancy, said it is encouraging the city is acting now. While cities up and down the California coast have acknowledged the issue, not many have begun acting.
They said the study will look at models for the year 2100 and what steps the city can take now to address those findings. However, the study is complex and layered with numerous considerations such as storm patterns, king tides, Encinas Creek, traffic engineering, construction, public outreach and which spaces are most resilient within the project.
Fields said one deliverable is for a 30% engineering design for the roadway realignment with the southbound lane (closest to the coast) moving inland.
“It will be an inland migration of the southbound lane into a combination with the northbound lane and a footprint with the northbound lane,” Fields said. “It does have a lot of complex components within the project because it is this whole revisioning of this one-mile section of the coast.”
Adam Young, a project scientist with Scripps, said there are two goals for his portion of the project, analysis of historical data to assess coastal erosion and modeling of a future coastline.
Young said the erosion projections are currently underway and expected to be completed sometime next year. The project team will use a variety of models to form a consensus on predictions regarding how high sea-level rise may be and what impacts erosion may have west of Carlsbad Boulevard, also known as Coast Highway.
“We’re assessing the rates of erosion so they can design properly so the roadway is far enough back, so it won’t be threatened by erosion in the future,” he added. “I do think using a variety type of models help form the confidence in the outcome.”
The study will also other potential land uses, such as a 62-acre park with an open space the council discussed during its Oct. 12 meeting as part of the Local Coastal Program update.