Author Topic: Aygill Caverns - !WARNING!  (Read 5446 times)

Offline darklord

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Aygill Caverns - !WARNING!
« on: November 20, 2020, 01:43:33 am »
!WARNING!

Erosion of the stream bank just downstream of the entrance to Aygill Caverns (near Bull Pot Farm) has drastically altered the local hydrology of Aygill, with serious consequences for access to the cave.

The gill has been steadily eating away at the bank for several years now, but without significant impact on access to the cave. This has all changed in the past two months.

On the 7th October during a resurvey trip the normal dry route to the Traverse Pitch was taken. At the bottom of the pitch a significant stream was found flowing from the upstream passage, which for many years has only contributed a trickle or small stream at best. The large stream was now flowing into the short low tube which leads to the second pitch and the main cave. The tube wasn't attempted, but would likely have been 'sporting' at the very least, and the pitch would have been a full-on cataract.

On the 18th November another trip was made to check on the water below the Traverse Pitch, as it was noticed that more of the surface stream appeared to be sinking than a month earlier. On this occasion the caver was stopped a mere 10 metres into the cave where a low crawl and short rift descend to a squeeze or wriggle through to an enlargement. This normally dry route was completely engulfed by a large stream issuing from the roof and falling down the rift to the squeeze. This would have been silly to attempt, and the squeeze would likely have offered a drowning experience.

On the 19th November, after 24+ hrs without rain, I returned to take another look at the situation.  The surface stream had subsided to a moderate-to-normal flow. Once again, 10m into the cave a large inlet was met and, although slightly less boisterous than the previous day, it effectively stopped any further investigation.  New cavities in the roof and wall suggest that the stream has loosened a lot of boulders which will have been washed down and most likely choked up against the squeeze at the bottom of the rift.

Effectively this situation closes the cave, either until a period of much drier weather, or until an efficient dam is built around the new sink.

* IT IS ADVISED NOT TO VISIT AYGILL CAVERNS UNTIL FURTHER NOTICE

(pic. shows inlet above rift/squeeze on 19/11/20 after 24+hrs without rain)

Offline CNCC

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Re: Aygill Caverns - !WARNING!
« Reply #1 on: November 20, 2020, 08:31:19 am »
Hi Darklord, thank you for posting this. We have added your warning to the CNCC website to see this circulated as widely as possible, as we know Aygill is a very popular trip that has seen increasing numbers of visitors in recent years. Please keep us updated if anything changes. If any support is needed for any restorative works please let us know.
Council of Northern Caving Clubs; Working together for northern caving since 1963

Offline alanw

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Re: Aygill Caverns - !WARNING!
« Reply #2 on: November 22, 2020, 05:31:58 pm »
We took a wander over to have a look this afternoon and took a few pictures.

Working upstream, there is a dig at SD 66291 81856, a possible sink at SD 66297 81849, Our Lady's Cave at SD 66333 81836, and directly opposite what looks to be the new sink: SD 66340 81838. Finally, the entrance to Aygill at SD66346 81843.

Any more heavy rainfall will further erode the steep bank behind the new sink, which is currently taking about half the flow.

Restricted to 6 attached images, only those of the sinks are here, at low resolution, all can be found at full resolution at https://www.rfvt.org.uk/aygill/. At least in Firefox, clicking on the image will scale it down to fit in the screen.


Offline darklord

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Re: Aygill Caverns - !WARNING!
« Reply #3 on: December 06, 2020, 12:28:57 pm »
*UPDATE*

A temporary diversion dam has been built (thx. Andy Walsh/Bill Sherrington, RRCPC) to channel water past the new sink. In low flow conditions this does mostly bypass the new sink and stop the leakage into the cave. (see pic)

On Friday 4th December I made a quick trip into the cave to find only a small inlet entering where previously it had been a cataract. It was possible to scramble down the rift to the former 'pincer' squeeze.  This is no longer visible and is buried beneath the best part of a metre of compacted cobbles and gravel. THERE IS NO ACCESS BEYOND THIS POINT.

The rift where the inlet enters has been considerably modified and de-stabilised with boulders and large cobbles liable to further collapse down onto the new choke.

A plan is being made for a more permanent dam around the sink area, and if successful this will allow access to dig out the pincer choke and do remedial stabilising work on the inlet area and rift slope.  Both surface and internal work are considerable undertakings. Given we are heading into winter weather it is unlikely this work will be possible before spring.

* Please consider Aygill CLOSED UNTIL FURTHER NOTICE.

Offline Fulk

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Re: Aygill Caverns - !WARNING!
« Reply #4 on: December 06, 2020, 02:27:31 pm »
What is the 'pincer squeeze'?

Offline Alex

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Re: Aygill Caverns - !WARNING!
« Reply #5 on: December 07, 2020, 10:30:04 am »
If I can get past the police, do you want a hand digging it out this weekend?
Anything I say is represents my own opinion and not that of a any club/organisation that I am a member of (unless its good of course)

Offline MJenkinson

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Re: Travel and other Covid Rants
« Reply #6 on: December 08, 2020, 09:40:05 am »
Alex - if you PM me your email I can pass it on to those who are likely to be getting on with this.

Offline PeteHall

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Re: Aygill Caverns - !WARNING!
« Reply #7 on: December 08, 2020, 02:56:44 pm »
Discussion on travel and other Covid rants have been moved here: https://ukcaving.com/board/index.php?topic=27292.msg333471

Offline darklord

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Re: Aygill Caverns - !WARNING!
« Reply #8 on: December 08, 2020, 05:20:16 pm »
What is the 'pincer squeeze'?

It's a slot at the bottom of a rift about 10m into the cave - perhaps not technically a squeeze, depending on your size, but you have to get down on the floor and wriggle through feet first for a body's length to an enlargement.  Without proper dam work you will have half of Aygill surface beck crashing on your head at this point, likely with an unhappy outcome!

Offline darklord

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Re: Aygill Caverns - !WARNING!
« Reply #9 on: December 08, 2020, 05:23:48 pm »
If I can get past the police, do you want a hand digging it out this weekend?

Thanks for the offer, Alex, but the whole project needs better weather and a comprehensive plan.  We're working on the latter but obviously winter is not the best time for working on it.

Digging the blockage out is one thing, but pretty pointless unless an effective surface dam/diversion has been built - else it will just wash in and fill again on the next flood.

Offline Fulk

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Re: Aygill Caverns - !WARNING!
« Reply #10 on: December 08, 2020, 09:54:06 pm »
Thank you, darklord.

Offline Alex

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Re: Aygill Caverns - !WARNING!
« Reply #11 on: March 28, 2021, 10:46:42 am »
Was a little naughty (considering we are technically are now allowed out until tomorrow) and had a trip up to the Dales, yesterday. I took at look at this cave after potting about looking at various digs. The good news is, your damn is holding, the cave was completely dry (despite all the rain on Friday night), the loose cobbled passage leading to the squeeze don't look much worse then when I remembered it, but I can see if water gets in there again, more could be dragged in. Things do not appear to deteriorated further since the report in December, going from the descriptions above. However the blockage described is still there, I have compared my photos to those in December, it don't look any deeper. I spent 20 minutes digging it to see if I could then fit through but realised I was running out of stacking space and the bit I was trying to squeeze through may also be blocked not far in.

I think what's needed is a few drag trays and small spade to open it up. Depending on the depth you are looking at a day's work if a place to dump spoil is located. Stopping more spoil getting in there would be the harder job as there is about 5m of loose wall just up the passage, I don't know what to do about that other than to stop the water getting in there or cement all the rocks together?

An alternative is to cap/blast the rift above I can see through to wider space after 5m but that's going to be a lot more work than just digging the floor out again.

Not certain if anyone can see the below images...

Blockage after a bit of digging with just my hands.



Blockage before digging, with glove for scale




« Last Edit: March 28, 2021, 11:07:02 am by Alex »
Anything I say is represents my own opinion and not that of a any club/organisation that I am a member of (unless its good of course)

Offline PeteHall

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Re: Aygill Caverns - !WARNING!
« Reply #12 on: March 28, 2021, 09:05:24 pm »
Not certain if anyone can see the below images...

No...

Offline RobinGriffiths

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Re: Aygill Caverns - !WARNING!
« Reply #13 on: March 28, 2021, 09:25:22 pm »
403- Forbidden.

Offline Alex

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Offline andywebman

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Re: Aygill Caverns - !WARNING!
« Reply #15 on: May 16, 2021, 12:22:43 pm »
Work has now started on reopening the cave. A large contingent of Red Rose members worked all day diverting the stream away from the sink, building a reinforced dam and work underground with scaffold and walling to make the slope above the block age safe. The walling will be completed in the next few weeks and then we can dig out the blockage and have somewhere to puttee spoil. THE CAVE IS STILL BLOCKED so please keep away for the moment.
RRCPC:-)

Offline andywebman

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Re: Aygill Caverns - !WARNING!
« Reply #16 on: May 16, 2021, 12:25:22 pm »
The finished dam
RRCPC:-)

Offline braveduck

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Re: Aygill Caverns - !WARNING!
« Reply #17 on: May 16, 2021, 02:26:59 pm »
If the stream is still leaking through the boulders you may have to consider sealing it somehow .
May I suggest feeding chopped straw in followed by Postcreat .That should seal it instantly.

Offline Alex

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Re: Aygill Caverns - !WARNING!
« Reply #18 on: May 16, 2021, 03:19:36 pm »
I was just thinking of cementing all those loose boulders together, but that would have to wait until the next dry spell I guess (and who knows when that is). The actual blockage itself seemed easy to clear out as I got down a couple of feet with my bare hands when I was there a few months back. Just had no where to put it without a drag tray.
Anything I say is represents my own opinion and not that of a any club/organisation that I am a member of (unless its good of course)

Offline andywebman

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Re: Aygill Caverns - !WARNING!
« Reply #19 on: June 06, 2021, 03:07:57 pm »
Work has continued in the cave and on the surface over the last couple of weekends. We finally finished walling up and cementing the hanging boulder choke yesterday. The crawl at the bottom has now been dug out as well and the cave is open but only as far as the bottom of the 1st (Traverse) Pitch. More work has also taken place on the surface channel to improve the stream channel diversion.
The main way on is a slot in the floor beneath the pitch but a considerable amount of water has come down here over the winter washing away material that was supporting two large boulders that have to be passed to get into the slot. These are now very unstable and continuing on beyond this point is not recommended! We have a plan to make this safe but it may take a few weeks to get the plan into action.
RRCPC:-)

Offline andywebman

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Re: Aygill Caverns - !WARNING!
« Reply #20 on: June 06, 2021, 03:12:58 pm »
I was just thinking of cementing all those loose boulders together, but that would have to wait until the next dry spell I guess (and who knows when that is). The actual blockage itself seemed easy to clear out as I got down a couple of feet with my bare hands when I was there a few months back. Just had no where to put it without a drag tray.
We have just completed cementing. see below
RRCPC:-)

Offline andywebman

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Re: Aygill Caverns - !WARNING!
« Reply #21 on: June 25, 2021, 10:32:57 am »
We have now drilled holes in the two dangerous boulders ready for breaking them up! Please keep away from the cave for the moment while we continue this work.
RRCPC:-)

Offline darklord

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Re: Aygill Caverns - !WARNING!
« Reply #22 on: July 01, 2021, 01:59:21 pm »
* UPDATE - 1 JULY *

THE CAVE REMAINS CLOSED BELOW THE 1st PITCH

The dangerous large boulders beneath the 1st pitch have been chemically reduced and there is no passable route to the main cave.  Formerly, a slot down between the wall and these boulders led to a route beneath the boulders and on into a more solid tube to the 2nd pitch.  This is now completely blocked with rubble and debris.

Visits are not advised as the site of the former large boulders may still be unstable and liable to further collapse or sudden 'settling'. There is no way further into the cave.

Work will now commence to dig out and make safe a route to the 2nd pitch.

A further announcement will be made when this work is completed.  Until then the cave remains CLOSED.


Offline flakey

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Re: Aygill Caverns - !WARNING!
« Reply #23 on: July 18, 2021, 10:40:34 pm »
Update: 17th July

An RRCPC work party (Ray, Sam, Hugh, Dave, Phil) has cleared up the remains of the blasted boulders at the bottom of the first pitch, and built a retaining wall to open up and stabilise a new route into the tube below the first pitch.

The climb down still needs some more work and clearing up before it can be declared safe, so please don’t visit yet.

The new route down is the obvious hole on the true right face of the rift, directly at the bottom of the first pitch. Previously, it was a small tube on the true right face, a few metres upstream from the bottom of the pitch. You no longer need to due a 180 turn in this tube, due to how the boulder pile has rearranged itself. Beyond this tube, the cave is as described in guide books, unmodified by the floods.

Offline flakey

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Re: Aygill Caverns - !WARNING!
« Reply #24 on: July 21, 2021, 10:34:55 pm »
Attached are some before (standing on detritus and pondering) and after (posing on the ladder) photos of the bottom of the first pitch. The ladder now hangs straight into the continuation on the true right wall of the rift.

As a reminder, the route is not yet deemed to be totally safe. There’ll be an update when it is!

 

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