Caltrans will blast loose debris from the cliffs early next week


Posted by on Fri, April 7, 2006

Cheri Parr
The cracks on the road on the Slide are much bigger than they appear in some photos.

UPDATED APRIL 8, 3PM: Caltrans has delayed blasting from Sunday until "possibly Tuesday".

Caltrans is scheduled to begin blasting loose debris on the cliff above Devil’s Slide

on Sunday

  as early as Tuesday, "weather permitting".  Drilling equipment is already on Highway 1, just above the slide, waiting for the process to be completed.  Then crews will drill three 150-foot holes in the Slide so its movements can be measured.

Coastsider went out to the Slide again Friday afternoon at 4pm and it was clear that the roadway is continuing to slip toward the Pacific.

Caltrans is also preparing to put a gate on Highway 1 north of Graywhale Cove and south of the tunnel construction site. This, combined with the concrete barriers near the entrance to McNee Ranch State Park in Montara, will allow pedestrian access to Gray Whale Cove.  "We had a call from a person who was planning to get married there on April 29 and wanted to know if they needed to make other plans," said John Cunliffe, CalTrans spokesperson.

I hope you guys have arranged with CalTrans to get video coverage of the blasting.  From a safe distance, of course.

Coastsider - I have been coming here several times a day for news.  Many thanks.  Wish we had had this in ‘95.  It’s at least a reality check.  I remember last time - I kept thinking somehow it was going to get better.  At least this time we’re grounded in what’s really happening right away and can make instant plans.

I agree.  I can’t tell you how gratefull I am that we have you to document “beyond the barrier” of what is happening on the slide.  I’m not sure that CalTrans understands how difficult it is out here, and it’s made so much worse by the lack of information.  I’m also dissapointed the coverage by the Half Moon Bay Review.  After three days, I’ve quit going to their web site since everything I need and more is at Coastsider.  Barry, Darin and Cheri - Great job!

as early as Tuesday, “weather permitting”

Permission denied. NWS is confidently predicting “rain, heavy at times” on Tuesday.

First they said drilling friday, then blasting sunday, now nothing, nothing, and more nothing done after two days of nice weather. The delays have started and we are not a week into it.  Caltrans hard(ly) at work again.  Now the weather is coming and we’ll get nowhere for another week. They are probably going to punish us for pushing the tunnel down their thoats or, more likely, they are just plain incompetant.

Cheri and Barry,

Thanks for the great images.

Anyone can tell the main fracture at the spray painted white line running in a NW direction across the whole roadway is getting worse(images 3545 through 3565).  Wednesday’s images indicated the area of slipage was larger than the ten or fifteen feet just south of the fractures at the white line.  Images 3561 and 3562 looking south appear to indicate slumpage much further to the south of the white vehicle(not a good place to park).  This may indicate the width of the slipage.

Images 3590 through 3593 show sinking and a pavement fracture.  I’m assuming the images 3619 through 3628 of a new fracture are just south of the slumping in Images 3590 through 3593 because of the chainlink background and the distance from the steel Armco section attached to the K rails.  This may indicate the extent of the horizontal length(width) of the slipage.  I’d guestimate 75 to 100 feet.

Looking at the 1995 images of the slide by Mike Wong in a later article and these, the two road wide fractures appear to line up.

On the west side of the road bed, the outer K rail was undermined and slipped out. It is interesting that the appearance is the roadway bed and supporting earth dropped away intact from the asphalt.  The west side of the sunken K rails appear to be situated right next to the earth and vegetation like before the slip.  There aren’t indications that water undermined the roadbed at a depth of a few feet, because there isn’t any roadbed debris on the vegetation. So, I’d speculate a shallow water undermining of the roadway can be eliminated.

On the westside of the road bed there does not appear to be signs of fracture or slipage further west of the roadway. But, with guessing three feet of westward movement and three feet of downward movement spread out unifomly over 75 to 100 feet it may be hard to see slipage on the west hill side below the roadway.  In image 3613 it may be hard to see the fracture area.  There may be some bulging in image 3580 downslope of the sunken K rail. The images south of these points looks pretty stable.

I’m no expert.  The road surface is clearly deteriorating.  The width of the slip has manifested itself. It mathces up to the 1995 images. There doesn’t appear to be an undermining of the road but, rather a bulk roadbed sinking and sliding. The drilling information is important to know how deep the slide is and how much material is moving.

Vince Williams

Why did CalTrans delay the blasting?  Anyone know?

Marva Seaton

Does anyone one know if there is any truth to the *rumour* that Devil’s Slide may never reopen?  I find this hard to believe since it does not even seem as though CalTrans has a good idea of the rate slide, amount repairs necessary, etc. I would not think they could even make such comments until the drilling is complete.

Also, I did read on the Review site that CalTrans is not only delayed by the weather but by obtaining the necessary environmental permits to continue with blasting.



I also heard *rumors* the slide would never reopen.  When I asked for sources, I didn’t get any. So,
to me it’s just a rumor.

I doubt CalTrans would make a statement like that.
Why eliminate the option of just delaying?  They could study the geotechnical aspects, wait for it to dry out and stop sliding…  They could get lucky, it stops sliding, they fill it in, repave, clean out the drains and reinstrument it and they are the big heros for not a lot of cost.  This delaying is consistant with CalTrans prediction it could be months to reopen.

On the CalTrans site “Updates” there is a statement about obtaining “Right of Way permit from the land
owner that will allow crews to perform work above the roadway.”  I would guess this is a simpler process than obtaining “environmental permits”.

Vince Williams

Same here, I heard that report on the radio, but then it didn’t recur and I have seen nothing since.