Author Topic: Warning - Devonshire Mine entrance subsidance  (Read 3115 times)

Offline DCA

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Warning - Devonshire Mine entrance subsidance
« on: October 04, 2019, 07:18:56 pm »
Over the last day or 2 a small gap has opened up beneath the door at Devonshire Mine. Overnight this has grown to a much larger gap and there is evidence that the area has become unstable and is at risk of collapse. The deads that sit under the door have become dislodged and the whole area is settling. Please use the Upper Entrance (old show mine) to access the mine until further notice.
Safety warnings have been posted inside the mine and out and the landowner down the lane is aware.
DCA will try to establish a course of action as soon as possible once the movement has ceased. Please remember that this entrance is on a filled in shaft, so it would be wise to stay clear for now in case the shaft is attempting to un-fill itself!
Thanks to PICA member Tom Monck for the initial notification.
Pete Knight
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Offline Gritstone

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #1 on: October 04, 2019, 10:41:49 pm »
Just to clarify, is permission required to use the top entrance? I thought it was out of bounds in someone's garden. The last time I was in there was a new metal gate fitted. It was possible to get around the side of this but looked like a infill was due to be added.

Offline paul

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Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #3 on: October 05, 2019, 10:22:15 am »
Just to clarify, is permission required to use the top entrance? I thought it was out of bounds in someone's garden. The last time I was in there was a new metal gate fitted. It was possible to get around the side of this but looked like a infill was due to be added.
Things have moved on a lot since those days. See DCA website for current access info. Although a combination lock was initially fitted to the Upper Entrance, this has been removed and will stay off for the time being.

Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #4 on: October 05, 2019, 11:27:47 am »
Sorry, just seen that the Devonshire listing on the DCA site does not seems to have been up updated when we added the other entrances to the access agreement. I've just submitted the following text to correct that:
"Devonshire Upper Entrance is not mentioned on the listing. This does not require permission to use. A combination lock may be present, if so the code will be ****. There are plans to convert this Upper gate to a Derbyshire Key in future. The shaft from surface above the main chamber and just inside from the Upper Entrance is also approved for access."

Offline LarryFatcat

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #5 on: October 05, 2019, 12:15:32 pm »
Sorry, just seen that the Devonshire listing on the DCA site does not seems to have been up updated when we added the other entrances to the access agreement. I've just submitted the following text to correct that:
"Devonshire Upper Entrance is not mentioned on the listing. This does not require permission to use. A combination lock may be present, if so the code will be ****. There are plans to convert this Upper gate to a Derbyshire Key in future. The shaft from surface above the main chamber and just inside from the Upper Entrance is also approved for access."

Maybe the entry could also include a description of where the "Upper Entrance" is, inc a grid reference?

Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #6 on: October 05, 2019, 01:07:37 pm »
slightly further up the hill, next to the path.....
Dirty old mines need love too....

Offline royfellows

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #7 on: October 05, 2019, 03:14:10 pm »
Thanks for all this. I often use the place for testing new lamps.
Please keep the thread updated on latest on the new 'sinking', I am enthralled!
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Online Roger W

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #8 on: October 05, 2019, 05:13:44 pm »
You've not been melting the rock somewhere with your latest bit of kit, have you?
"That, of course, is the dangerous part about caves:  you don't know how far they go back, sometimes... or what is waiting for you inside."   JRR Tolkein: "The Hobbit"

Offline Graigwen

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #9 on: October 05, 2019, 06:38:24 pm »
You've not been melting the rock somewhere with your latest bit of kit, have you?

I used to call Roy's lamps "mobile suns".

.

Offline aardgoose

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #10 on: October 05, 2019, 07:15:45 pm »
Thanks AR, your description now included in the registry.

Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #11 on: October 05, 2019, 09:14:52 pm »
If you want to be completely accurate, it's about 100m further up the hill, where the path divides in two, take the right-hand branch then head into the deep cutting.
Dirty old mines need love too....

Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #12 on: October 07, 2019, 12:44:12 pm »
Would anyone be able to go into Devonshire in the near future and visit the chamber with the fill cone from the shaft and get some pics? It's most likely that it's on the move, hence the subsidence above at the door, but I'm out of action with a knackered ankle and Pete K is busy with work right now so someone giving us a better idea what's going on at the bottom of the fill would be a great help in coming up with a stabilisation plan.
Dirty old mines need love too....

Offline phizz4

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #13 on: October 07, 2019, 05:40:48 pm »
As we use the cave a lot with our scout groups i owe we owe it to the community to try to help. i can get there on Thursday or Friday evening if that is soon enough?

Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #14 on: October 07, 2019, 08:55:53 pm »
Any time soon is good, help is much appreciated while I'm laid up.
Dirty old mines need love too....

Offline phizz4

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #15 on: October 11, 2019, 11:38:10 pm »
I went down Devonshire this evening (Friday) to have a look at the damage and take some pictures. What's the best way of communicating the pictures and my findings to those that need to know?

Offline ttxela2

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #16 on: October 12, 2019, 09:58:27 am »
I have a vague recollection of accessing a small chamber directly underneath the entrance through a smallish tube like crawl, I'm guessing it's the roof of this that is collapsing?

Offline phizz4

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #17 on: October 12, 2019, 10:50:49 am »
A quick report. I can send a more detailed report and pictures but I tried to do that earlier on this topic and it hasn't posted, don't know why. The pack below the door at the lower entrance seems to have moved forward and down. I'm guessing surface run-off from the slope leading to the entrance. There seems to my non-engineering eye, to be no downward slumping. Some material is going down the muddy slope to the left of the entrance (looking out) that leads to the lower series but that seemed unchanged (although it looks like some hanging death in the ceiling but I think that has always been there). Went to the base of the infilled entrance shaft, I believe (behind the large rectangular block) where there are two upward chokes. The left one is jammed blocks which don't look to have moved. No sign of new debris on the floor. Slightly right is a much looser looking infill. Again, no sign of collapse but quite muddy and water has obviously been trickling down. Recent shoulder surgery (rotator cuff tear) prevented me from investigating small holes. There is still a padlock on the upper entrance gate but a hole to the left of the gate was easily big enough to allow me in.

Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #18 on: October 12, 2019, 10:51:26 am »
Drop me an email with some pics if you can please!
projects@thedca.org.uk
Cheers!

Additionally, I need to go take a look at Devonshire gate myself really, to start planning a fix. Anyone free later today or on the 15th or 16th to keep me company?

Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #19 on: October 12, 2019, 10:54:13 am »
A quick report. I can send a more detailed report and pictures but I tried to do that earlier on this topic and it hasn't posted, don't know why. The pack below the door at the lower entrance seems to have moved forward and down. I'm guessing surface run-off from the slope leading to the entrance. There seems to my non-engineering eye, to be no downward slumping. Some material is going down the muddy slope to the left of the entrance (looking out) that leads to the lower series but that seemed unchanged (although it looks like some hanging death in the ceiling but I think that has always been there). Went to the base of the infilled entrance shaft, I believe (behind the large rectangular block) where there are two upward chokes. The left one is jammed blocks which don't look to have moved. No sign of new debris on the floor. Slightly right is a much looser looking infill. Again, no sign of collapse but quite muddy and water has obviously been trickling down. Recent shoulder surgery (rotator cuff tear) prevented me from investigating small holes. There is still a padlock on the upper entrance gate but a hole to the left of the gate was easily big enough to allow me in.
Ah, well someone unknown has put a new lock on then!
Sound's like the shaft is not running in then, good news. Probably just needs a team with some rebar and load of mortar to build a new wall up where the orange ladder currently sits. Anyone local fancy heading this job up?

Online owd git

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #20 on: October 13, 2019, 08:48:58 am »
hi Pete, been too busy to commit till now; it will be done soon will report back!  Ric'.
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Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #21 on: October 13, 2019, 10:10:41 am »
From the photos that Pete and I have seen, it does look like there's just minor instability in the area under the door so if that's the case then a bit of excavation and rebuilding with reinforcement should fettle it. However, I'd value a second opinion from you Ric (twisted ankle is preventing me from going and seeing for myself!), so if you could head up there in the near future and let us know what you think, that'd be great.
Dirty old mines need love too....

Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #22 on: October 13, 2019, 06:32:02 pm »
hi Pete, been too busy to commit till now; it will be done soon will report back!  Ric'.
Thanks Ric. As Adam says, your opinion would be very valuable as I'm struggling to find the time for a look at the moment with other jobs that keep popping up!

Offline LarryFatcat

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #23 on: October 26, 2019, 12:07:13 am »
hi Pete, been too busy to commit till now; it will be done soon will report back!  Ric'.
There is a combination lock on the gate, the code works, and you can probably squeeze around it.

Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #24 on: October 26, 2019, 09:01:31 am »
One of the locals will have replaced it then. Code available via the DCA website.
https://peakdistrictcaving.info/home/the-caves/derwent-south/devonshire-cavern

Offline LarryFatcat

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #25 on: November 01, 2019, 11:28:38 pm »
One of the locals will have replaced it then. Code available via the DCA website.
https://peakdistrictcaving.info/home/the-caves/derwent-south/devonshire-cavern
yep the combo worked, I had forgotten to get it but phone reception near the entrance gave me internet access to the DCA registry and the 4 digit code

Offline SqueezyPete

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #26 on: December 08, 2019, 06:36:53 pm »
 What's the state of the lower entrance at the moment?

Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #27 on: December 08, 2019, 06:49:16 pm »
Unrepaired, so same as reported. Upper entrance fine.

Anyone fancy taking this job on? Some concreting and a bit of pointing up is all that is required.

Offline SqueezyPete

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #28 on: December 08, 2019, 10:56:22 pm »
 I'd like to help but I don't have much to offer, I like the cave because we can get to it easily without a car. I'd offer a helping hand after christmas if anything happens!

 Aside from the entrance subsidence the lower series should be grand to look around right? Assuming we take care with the bits near the infill.

Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #29 on: December 08, 2019, 11:13:24 pm »
From reports it seems there has been no movement in the mine itself, what we are looking at here seems only to be the collapse of the packwall built under the lower door frame, nothing more serious.

Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #30 on: December 09, 2019, 08:49:06 pm »
Pete, I'm going to try and take a proper look over the Christmas break.
Dirty old mines need love too....

Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #31 on: December 09, 2019, 08:54:29 pm »
Ace, meet too once I get quieter with work. Guess the ankle is better now then?
It's probably a bit cold for concreting now, but I don't think it is a big job once the people and weather are in place to do it.

Online owd git

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #32 on: December 10, 2019, 08:20:23 am »
Sorry! got reet busy Pete, has slacked off a little, phone or message if you set a time. Ric, 07790 694292  :thumbsup:
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Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #33 on: December 10, 2019, 08:51:39 am »
The ankle's about 90% of the way back to being fully operational, just need to keep doing my physio exercises to stretch and flex it.

I'll let people know when I'm thinking of heading up there, I'm thinking it might be possible to dig out underneath and rebuild with drystone packwall for the time being, and then go back and mortar it up later in the spring?
Dirty old mines need love too....

Online owd git

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #34 on: December 10, 2019, 11:13:06 am »
From my building experience, the temp' will be fine for mortar or concrete. it's sheltered enough to not be a problem ,short of a really cold snap.  :thumbsup: If it does drop I will fetch mortar anti-freeze.
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Offline Pete K

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #35 on: December 10, 2019, 07:45:12 pm »
Ah great, that's handy to know.
I'm probably not going to personally get a chance to deal with this until at least mid Jan. I might be able to get over for a look before, but certainly not to organise the job. I'll let AR go take a look and once we are certain of the fix that needs doing, we can see about trying to find someone to coordinate the work. If you up for that OG, and want to pick a date that works for you, DCA will naturally cover all costs and I can find as many local helpers as you need. No probs if you're too busy, it can keep for a while as there is another way in after all.
Pete

Online owd git

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #36 on: December 10, 2019, 08:03:39 pm »
Two man job  easy. have a willing idiot in mind. :lol :Cheers Pete & Adam.
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Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #37 on: December 28, 2019, 09:33:37 pm »
Update - December 28

Having a couple of hours free this afternoon, I've been to take a look and start the repair work. On arriving at the door, I found there was a very large gap underneath it that could easily be squeezed through (see pic 1), the hazard tape was broken, and the door wasn't bolted  - to whoever has been going in this way, all I'll say is which bit of "do not use this entrance" don't you understand, and would you like it explaining in words of one syllable whilst being hit round the head with a shovel?

First job needed was to clear all the old soil and leaf mold from around the door; this is a job that really needs doing every couple of years to keep a free swing. Ten minutes with the folding shovel had this sorted, though I upset a lot of worms in the process.  Next, I had a good look at the inside; the large boulder and its surrounding rocks didn't look to have moved, it was the choss on top of it that had gone downslope and caused the hole.

There was plenty of rock in the entrance chamber so I set to work creating a packwall to fill up the gap and spent the next hour walling. As can be seen from photo 2, I've got  the gap mostly filled up but not completely, so more work is needed and mortaring up to really secure everything. In the meantime, please continue to only use the upper entrance. I also think there's some work needed on the big stones below to make certain they don't move. Photo 3 shows just how big the hole under the door had got!
Dirty old mines need love too....

Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #38 on: January 14, 2020, 10:57:13 pm »
Update 14/1/20 - Another session tonight, this time with help from Richard Finnigan, Mart Long, Shirley Burtonshaw and Arthur Wilson. Richard and Mart dealt with the bit under the frame, I rebuilt the bits behind the ladder, while Shirley and Arthur fetched stone for us.

The packwall is now much more solid, Richard rebuilt some of the bits I'd done in a hurry on the last session with more care and attention. Mortaring still to do though....
Dirty old mines need love too....

Offline royfellows

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #39 on: January 15, 2020, 08:56:01 am »
I cant help wondering whether concrete would form a better solution?
Relatively easy to get materials close to the mine, plenty water inside not far in.

Mortaring the packwall built would possibly make something more permanent?
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Offline AR

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Re: Warning - Devonshire Mine entrance subsidance
« Reply #40 on: January 15, 2020, 10:06:58 am »
The packwall needs to be semi-permeable to cope with drainage from outside coming into the old shaft, so I think what's needed is just mortaring gaps up enough to stop the packwall moving but not so much to stop water getting through. I do need to go back when the weather's drier and repaint the door....
Dirty old mines need love too....