Sunday River Lift Falls Over

[rogman]

WTF?

On Sunday evening, July 10, 2016, Sunday River Resort's lift maintenance manager discovered that the foundation of the top terminal of the Spruce Peak Triple chairlift had become detached from the underlying ground...

http://sundayriver.com/news

[Mister Moose]

2 part casting that failed?

Sure wish their photo was bigger.....

[freeski]

Lucky it didn't give way from the weight of skiers. A lot more force when it's loaded. The footing failed or the anchor bolts that goes into the bedrock? This is amazing. WTF is right.

[steamboat1]

One word:

Boyne

[spanky]

WTF?

On Sunday evening, July 10, 2016, Sunday River Resort's lift maintenance manager discovered that the foundation of the top terminal of the Spruce Peak Triple chairlift had become detached from the underlying ground...

http://sundayriver.com/news

Gives new meaning to "detachable" chairlift.

[Big Bob]

One word:

Boyne

No, Bovering

[E O Eleven]

[DrJeff]

One word:

Boyne

No, Bovering

Yup,

Both of the lifts at Sugarloaf that had issues were Borvigs. This lift at Sunday River is a Borvig. The double at Suicide Six that had tower issues and is being replaced is a Borvig. The Lift at Timberline in West Virginia that had a tower issue in the last season or 2 is a Borvig.

Borvig fixed grips are quickly getting the reputation that Yan detachable quads got 20 odd years ago these days

[Highway Star]

That'll buff right out.

[da Pimp]

I would investigate the ground around it, water flow can really eat away earth in a hurry. If the typical water runoff flow changed, it might have undermined key areas and allowed the concrete to shift, then once it is loosened it is a mater of time.

[freeski]

Lucky it didn't give way from the weight of skiers. A lot more force when it's loaded. The footing failed or the anchor bolts that goes into the bedrock? This is amazing. WTF is right.

Nice work Detective Freeski.

Lucky that you weren't skiing this weekend at SR.

What do you think is the difference in downhill force on the lift between when it's full of skiers or not in use It's amazing it failed in the summer. This could have been a disaster. Thanks for not posting much lately. Keep up the good work.

[f.a.s.t.]

Looks like Sunday River will be getting a new lift before Killington. I wonder if the next inspection would have caught the problem?

[freeski]

This was posted on AZ by Machski who sometimes posts here. He often has great insight on lifts:

"Wow, everyone is jumping on Borvig fast. This is a bit different, it is the concrete footing/anchor that gave way. Could it be a design flaw from Borvig engineering? Possibly. Could it be poor concrete from the supplier when poured? Possibly. Could it be bad site selection for the footing? Possibly. We'll have to wait for the investigation results to know for sure. I can tell you as I ski a ton there, where the Spruce top anchor is, that terrain it sits in is like a bowl. r*in water does not drain well away from that footing (or several of the tower footings towards the top as well). I have a feeling drainage will be sited as a major factor here. If the ground started giving first, allowing a touch of movement of the anchor, that could have been enough force to then rip apart the concrete/rebar structure like you see if a picture. That anchor has to exert a massive amount of force 24/7 just to counter the empty lift.

My guess is if they repair, the top terminal gets moved above the current unload (like more in line almost with the patrol shack at the top) to give that footing better drainage. As for the carpet, it could not be used with a Quad. It is not wide enough for four abreast loading."

[Mister Moose]

What do you think is the difference in downhill force on the lift between when it's full of skiers or not in use It's amazing it failed in the summer. This could have been a disaster.

The force acting on the return terminal, and the footing, is double the line tension. Depending on how the tensioner is designed, the tension in the summer might well be the same as when operating. (There is no more sag in the summer than winter, correct?, ie they don't relax the tension in the summer) And sag between towers when loaded does not imply the tension has changed either. Load affects braking, load affects weight on the towers, load affects sag, load affects current required to turn the motor, but I don't think load affects the tension. I can see if the seals are worn, a hydraulic tensioner might relax a little over time in the summer.

Even in that tiny photo I'm looking at the shape of the failed concrete on the lower footing that failed. We know that the rebar didn't fail, it held and pulled out of the footing. This is more than just simple erosion. The footing would have rotated in its entirety if the concrete was intact and the footing lost its support. Why are there no chunks of concrete clinging to the rebar? That's another relevant question I'd think. Perhaps the moisture path traveled along the rebar?

The shape and texture (what little you can see) of the failed concrete reminds me of old spauled concrete, weakened by many freeze thaw cycles and flawed by microscopic cracks or air that was in the mix. Any salt used in the area may have contributed, some salts are highly incompatible with concrete.

The last inspection was last fall, less that a year ago. No doubt signs were there if anyone had looked, but that might require digging or core samples, something I'm guessing isn't ordinarily done. With all the reinforced pre-stressed concrete bridges out there today, there must be a way to evaluate the concrete that is non destructive.

[machski]

What do you think is the difference in downhill force on the lift between when it's full of skiers or not in use It's amazing it failed in the summer. This could have been a disaster.

The force acting on the return terminal, and the footing, is double the line tension. Depending on how the tensioner is designed, the tension in the summer might well be the same as when operating. (There is no more sag in the summer than winter, correct?, ie they don't relax the tension in the summer) And sag between towers when loaded does not imply the tension has changed either. Load affects braking, load affects weight on the towers, load affects sag, load affects current required to turn the motor, but I don't think load affects the tension. I can see if the seals are worn, a hydraulic tensioner might relax a little over time in the summer.

Even in that tiny photo I'm looking at the shape of the failed concrete on the lower footing that failed. We know that the rebar didn't fail, it held and pulled out of the footing. This is more than just simple erosion. The footing would have rotated in its entirety if the concrete was intact and the footing lost its support. Why are there no chunks of concrete clinging to the rebar? That's another relevant question I'd think. Perhaps the moisture path traveled along the rebar?

The shape and texture (what little you can see) of the failed concrete reminds me of old spauled concrete, weakened by many freeze thaw cycles and flawed by microscopic cracks or air that was in the mix. Any salt used in the area may have contributed, some salts are highly incompatible with concrete.

The last inspection was last fall, less that a year ago. No doubt signs were there if anyone had looked, but that might require digging or core samples, something I'm guessing isn't ordinarily done. With all the reinforced pre-stressed concrete bridges out there today, there must be a way to evaluate the concrete that is non destructive.

Yeah, I'd lean towards saturated ground shifting and then possibly the quality/condition of the concrete at this point as where I'd look first. Spruce is in fact counter weight tensioned (the only non hydraulic tensioner left on the mountain) which I doubt played a roll, but ironic. In any event, that top anchor point has to counter a ton of force all the time. Even unloaded, a lift has a ton of weight to it, and all that acts as a downhill force on that anchor point.

I suspect if they repair/replace just the top return, they move it slightly uphill into the clearing at the top. Hard to pin this on Borvig at the moment. If it turns out to be bad and below grade concrete, that could be tied to the concrete supplier. This event is definitely different than all previous Borvig ones and any link to previous is speculative at best.