Study set for slippery grade

By Adam Spencer, The Triplicate May 01, 2013 03:57 pm

What could make Last Chance Grade even less stable? Climate change and the resulting rise in sea level.
What could make Last Chance Grade even less stable? Climate change and the resulting rise in sea level. Photo courtesy of F.L. Hiser Jr.
Sea level rise could make a bad situation even worse

The future of Del Norte’s notoriously slippery slope, Last Chance Grade, in the face of climate change’s rising sea levels and extreme weather events, will be the focus of a new Caltrans study.

Caltrans District 1 was awarded a $200,000 “climate adaptation grant” from the Federal Highway Administration to assess short- and long-term climate change adaptation strategies in four pilot project locations, including Last Chance Grade and its chronic landslides. Caltrans will match the grant with its own $200,000.

Ocean waves smashing into the base of the slide expedite the loss of material at Last Chance Grade, and with higher seas comes more erosion.

“Last Chance Grade is absolutely impacted in all of the potential climate change ways, including sea level rise and longer spells of dry conditions followed by a great amount of rain,” said Tamera Leighton, Executive Director of the Del Norte Local Transportation Commission.

One of the criteria for eligible projects from the federal program is that solutions identified through the study can be applicable elsewhere, and Last Chance fits the bill.

“We’re certainly not the only place with a road on a hillside over the ocean,” Leighton said.

The other project areas are subject to frequent flooding and/or expected to be impacted by sea level rise: a stretch of U.S. Highway 101 along Humboldt Bay; State Route 1 near Garcia River in Mendocino County; and flood-prone local streets on an area of the northwest shore of Clear Lake (Lake County).

Leighton said she recommended Last Chance for the project because “for me it’s important to continue to highlight our problems on Highway 101 at Last Chance Grade in whatever way that I can.”

A $9 million stabilization project completed three years ago at Last Chance Grade proved powerless at slowing the slide, after one storm made the stabilization structure drop 4 feet, Leighton said.

Current one-lane traffic control  on Last Chance Grade is not expected to end until August, Leighton said.

That Caltrans project, which involves drilling supports 120 feet into the ground, has ran into unexpected delays associated with relocating all of the groundwater encountered at those great depths, Leighton said.

“Nobody who I talk to believes that the management of the project is adequate — not the department, not me, not my transportation commissioners. We all know that what we’re doing is inadequate;  We just haven’t been able to find anything more reliable to do yet,”  Leighton said.

She is hopeful that this study might change that.

“The results of this project will go back to decision-makers across the nation and somebody else will hear about Last Chance Grade, and when it comes time to find a solution to this project, maybe it will help us secure funding in the long run,” Leighton said.

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