Eyam Dale Shaft resin anchor replacement

[DCA]

Please note that there are currently no anchors at the top of the Eyam Dale Shaft entrance to Carlswark.
The anchors had previously been reported as worn, and on inspection today it was decided that they both needed to be replaced asap due to large wear grooves being present on the anchor eyes. Unfortunately I was clearly suffering from post-Xmas brain fog this morning and managed to leave the resin applicator gun at home, and was too far into the job to stop by the time I noticed that it was missing. Both original anchors have been removed and the new placements have been drilled and prepared ready for the replacement anchors to go in. I'll try to do that this week (and the return visit to test them) and will post updates here.
Apologies for any inconvenience. I hope to be able to sort it ready for use next weekend.
Pete K
DCA Equipment Officer

 

[ChrisB]

Do you know what caused the wear on the removed anchors? I expect CNCC would be interested if it's a result of pull-throughs.

 

[Pete K]

Do you know what caused the wear on the removed anchors? I expect CNCC would be interested if it's a result of pull-throughs.

Pull through descents. It's a classic spot for doing simple through trips for clubs and instructed groups.
The new anchors will have rings on them to give a very long working life (existing anchors are 15+ years I think).

 

[Pete K]

Just checked the records. The 2 bolts we pulled out yesterday were installed in 1992 and 1996. That's a pretty good lifespan!
The wear doesn't look as bad in the picture as it is in person. Not sharp but certainly a good % of metal lost. Wouldn't have been a risk to any one at this stage, but the best time to retire critical safety gear is before it becomes dangerous, not after!

 

[Babyhagrid]

Just checked the records. The 2 bolts we pulled out yesterday were installed in 1992 and 1996. That's a pretty good lifespan!
The wear doesn't look as bad in the picture as it is in person. Not sharp but certainly a good % of metal lost. Wouldn't have been a risk to any one at this stage, but the best time to retire critical safety gear is before it becomes dangerous, not after!

View attachment 21472

Any chance of a caliper reading of the minimum diameter compared to the unworn diameter

 

[Pete K]

Sold as 8mm rod anchors, measured with the digital callipers at 7.9mm.
One anchor measured 6.4mm in the groove, the other was 6.2mm.
That is an approx' drop of 21% from the nominal diameter if my maths is correct.

 

[Brains]

Got to be better than abbing of the rotting tree that used to be there...

 

[DCA]

As is usually the case with most bolt installations, more time was spent pondering where to place the anchors than it took to install them. It was only possible to reuse one of the Y-hang holes, so a new left-hand Y hang anchor was placed in the back wall of the shaft. This avoided the already hole-riddled section of wall around the previous DMM anchor, and also sits the centre point of the Y hang in free space away from the rock. This should reduce rub on your rigging and make a pull through smoother. A 90 degree Y hang will sit approximately the same height as it was with the previous anchors.
As you can see, the Y hang anchors each come with an 8mm stainless steel ring fitted (done by Bolt Products for us especially) for threading your rope for pull throughs. Hard rigging for SRT or ladder/lifeline to the bolt eye will give a higher Y hang, but re-rigging the rope through the rings if you intend to pull through once down will prevent wear to the anchor eyes. The DMM anchors lasted around 30 years, so hopefully these BP ones will see me out!
With a reduction in the number of available (sometimes questionable) trees to rig a backup to, we also took the opportunity to place a couple more anchors on the right wall to rig a short traverse to protect cavers as they lean out over the shaft to the Y hang. 2 bolts might seem like overkill, but it's a policy that any installations we do give you 2 solid anchor points before you are exposed to a drop. It's up to you if you use them but it'll only require a few extra meters of rope. We didn't have a long enough rope with us to check the full length now needed to rig, but the 20m length for SRT given on the new rigging topo will certainly be enough. We can always change the figure in future if that proves to be far too much rope. A 25m+ rope will be needed for a pull through.
The anchors have all passed their 6kN 60 second test and the tags have been removed. Hopefully you'll find the new rigging an improvement.
Pete K
DCA Equipment Officer

Stoney Middleton : Carlswark Cavern, Eyam Dale Shaft : Details

Locations: Peak District, Location: Derbyshire, Location: Staffordshire, Caves, Mines, Potholes, Caving, Potholing, Guides, Surveys, Speleology, Hydrology

www.peakdistrictcaving.info

 

[wellyjen]

As is usually the case with most bolt installations, more time was spent pondering where to place the anchors than it took to install them. It was only possible to reuse one of the Y-hang holes, so a new left-hand Y hang anchor was placed in the back wall of the shaft. This avoided the already hole-riddled section of wall around the previous DMM anchor, and also sits the centre point of the Y hang in free space away from the rock. This should reduce rub on your rigging and make a pull through smoother. A 90 degree Y hang will sit approximately the same height as it was with the previous anchors.
As you can see, the Y hang anchors each come with an 8mm stainless steel ring fitted (done by Bolt Products for us especially) for threading your rope for pull throughs. Hard rigging for SRT or ladder/lifeline to the bolt eye will give a higher Y hang, but re-rigging the rope through the rings if you intend to pull through once down will prevent wear to the anchor eyes. The DMM anchors lasted around 30 years, so hopefully these BP ones will see me out!
With a reduction in the number of available (sometimes questionable) trees to rig a backup to, we also took the opportunity to place a couple more anchors on the right wall to rig a short traverse to protect cavers as they lean out over the shaft to the Y hang. 2 bolts might seem like overkill, but it's a policy that any installations we do give you 2 solid anchor points before you are exposed to a drop. It's up to you if you use them but it'll only require a few extra meters of rope. We didn't have a long enough rope with us to check the full length now needed to rig, but the 20m length for SRT given on the new rigging topo will certainly be enough. We can always change the figure in future if that proves to be far too much rope. A 25m+ rope will be needed for a pull through.
The anchors have all passed their 6kN 60 second test and the tags have been removed. Hopefully you'll find the new rigging an improvement.
Pete K
DCA Equipment Officer

Stoney Middleton : Carlswark Cavern, Eyam Dale Shaft : Details

Locations: Peak District, Location: Derbyshire, Location: Staffordshire, Caves, Mines, Potholes, Caving, Potholing, Guides, Surveys, Speleology, Hydrology

www.peakdistrictcaving.info

View attachment 21497View attachment 21498

That looks excellent. The most recent Crewe rigging guide update needed a long traverse line to a half way decent tree and an iffy spit anchor, so some resin anchor protection before the Y hang is most welcome. Will be a few days before the Crewe guide can be updated, but it'll get done soon.

 

[AlanClark]

Excellent work there Pete.

Any plans to test the old worn anchors to failure?

 

[Pete K]

My own test kit won't be able to manage that, they'll probably still need way more than the 20kN my Hydrajaws is rated to. The stems are also fairly gouged up from drilling down the sides to remove them, so that might affect the test result. I'm hoping to get my hands on the BCA's big hydraulic puller soon for a DCA testbed, and could perhaps try and get these old anchors glued back in and pulled out again. I'll not chuck them away just in case I can do something with them.

 

[wellyjen]

A 25m+ rope will be needed for a pull through.

I did measure the pitch height from the old anchors as 12m a few years ago, so yes, 25m plus to pull through.