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Protecting California’s Coast With Armor And Habitat
Tuesday, March 26, 2019
Photo by Matthew Bowler
Highway 101 is busy. People driving between Solana Beach and Encinitas can take the scenic road instead of hopping onto the nearby, but frequently congested Interstate 5.
Encinitas City Council Member Kelly Shaw Hinze said the road draws more than just car traffic.
“So this is a stretch of highway where people like to run, ride bikes and take in this sort of amazing scenic view shed that we have on either side of the highway,” Shaw Hinze said.
The council member stood next to large rocks which line the eastern side of the road. The boulders, or rip-rap, offer protection from big waves that are pushed ashore by high tides and storm surges.
The boulders serve as a last defense against an ocean that is increasingly putting pressure on local shorelines. On some stormy days, it is best to drive on the freeway.
“The highway was built on a very vulnerable sand spit. And this is what has been there to protect it for the last couple of decades. But as the conditions change and we start seeing more frequent high tides. What we’ve seen is that the highway becomes more vulnerable than it has been before,” Shaw Hinze said.
And this is a roadway the coastal communities want to keep open. Photographs from 2010 show standing water on the highway and in the parking lots of several local businesses.
“It has a history of going completely over 101 and closing the road and eroding it. And we’ve had larger storms damage,” said Pete Milligan, city of Encinitas civil engineer.
Highway 101 also flooded earlier this winter during a high tide that was coupled with a storm. At one point storm fueled waves pushed cobblestones on the surface of the blacktop.
Milligan hopes to protect the road through a unique plan that also creates a sandy dune habitat, which is pretty rare along the California coast.
The just over $2 million Cardiff Living Shoreline Project is due to be complete in April.
As part of the project, crews have been digging a deep trench along the highway.
“They come in and put filter fabric, the black fabric in and that really helps with the water not being able to get under the rock. Erode the sand and basically keeps it in place,” Milligan said.
On top of that fabric, workers have strategically placed interlocking large boulders that are basically an underground wall.
The large rocks, or revetment, are covered-up with sand dredged from the nearby lagoon.
“We have a final line of defense, the rock, which is going to save the road. But everything in front of it we’re going to have to adjust and perfect as the project goes along over time. But if it was just sand it would just go and we’d be in the same condition that we were before,” Milligan said.
The sandy habitat area on top of the rocks is roped-off and protected. It will be allowed to settle and drain before native plants are added.
That is exactly what conservationists did on a test project at the southern end of this beach where there is a patch of dune habitat that used to be a parking lot.
“This is a pretty good representation of exactly what the dunes should be looking like,” said Bradley Nussbaum of the San Elijo Lagoon Conservancy.
He pointed to the rehabilitated patch of sand.
“Kind of a nice little hummock flowing on it with vegetation. And this will probably be about the same density of vegetation that we’ll be experiencing there,” Nussbaum said.
The dunes will offer space for flowers like the beach primrose, which sports bright yellow blooms, and the purple blossoms of Sand Rabina.
The habitat should also be an inviting space for the western snowy plover. This beach is already one of the most popular roosting spots for that federally endangered bird.
“With this 60-foot of protected dune area where people won’t be walking. That’ll give them space where they can actually where they can keep away from potential traffic,” Nussbaum said.
The project is a complicated partnership between conservation groups, local governments and state agencies. All are watching closely to seeing how the project stands up to the pounding the ocean can bring. It will be a work in progress.
“We’re not going to expect these dunes to be frozen in a moment of time. Sort of the beauty of it is they can change, they can be dynamic,” Shay Hinze said.
Project managers concede this is not a permanent protection for the road.
The ocean will eventually reclaim Highway 101 as sea levels rise, but there is hope this project will protect the road and create rare habitat for several more decades.
Engineers are manufacturing a solution to help protect a busy coastal road in San Diego’s North County. If nothing is done, rising sea levels will increasingly threaten to wash out Highway 101 between Encinitas and Solana Beach.
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