Conniston Copper Mine Dive; a good old fashioned uk dive

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Technical Diving Article.

Conniston Copper Mine Dive; A good old fashioned UK dive

6ft square vertical shaft; 309 meters/1014ft deep

By Deep Wreck diver:- Mark Ellyatt

Holder of “Worlds Deepest Ever Wreck Dive”

Plan of Conniston Copper Mine.

Note 1 fathom=6feet. The flooded mine is 1,200 feet deep

Saturday 26 Oct 2002, the date for my latest sortie into Coniston Copper

Mine. This would be dive five in the mine, planned dive depth 237m. At this

depth the original copper ore work face would join the main shaft,

according to the mines original plans. The four previous dives were

carried out to obtain video footage and feel more comfortable with the 309m

deep, 2m square shaft with its 9'c water temp and pitch black darkness.

Finding buddies who would assist in diving the mine was almost as tricky as

the dives themselves. The deep shaft is 300m back in a hill side, you have

to cross a river to get to it, its totally without light and freezing cold

! (oh yeah and has frequent rock falls in places)

Christina Uwins (Medical student / Divemaster) and Brian Gilgeous

(commercial dive company owner who lifted Donald Campbells BlueBird) were

ideal for the job. Both had dived the mines before, both were experienced

with technical diving, and decompression medicine and even better, both

were free that weekend !

Jeff from the nearby Coppermine's museum, was a mine (free pun) of useful

information. As the museum's custodian he had access to articles and plans

going back to the mid 1800's, and was very helpful with his huge knowledge

of the mine systems. The deep level mine had ceased work in the 1892 and

had taken 5 years to fill up with water when the pumps ground to a halt.

The hair raising stories of the copper mine workers 150 years back would

send shivers down anyone's spines.

The weather that weekend was wet and windy, the mine entrance can only be

reached by crossing a rain swollen river.Christina, Brian and I carried

the equipment into the mine over 2 days in 6 hour shifts ! Carrying twin 20

litre tanks over rapids takes a lot of care. When all the kit was in

place, the deco tanks staged on lines, we exited the mine to relax and suit

up before the dive.

Entrance to Conniston Copper Mine, The Lake District, United Kingdom

Dive tanks were a 20 litre twinset of Trimix 5/76 bottom mix, stage tanks

of Trimix 14/50 and Trimix 20/30. Brian would descend to 60m supply backup

20/30 and remove the used 14/50. Christina would descend to 40m with Nitrox

32 and 36. At 21m a 20 litre stage tank of Nitrox 50 was pre staged

together with a 7 litre of Nitrox 50. The 20 litre tank was to be used

during in water recompression if the need arose. At 6m we staged a 12 litre

twinset of oxygen with long hoses to reach the 3m 2m and 1m stops.

Attached to the big twinset was the argon suit inflation, and battery packs

for Otter Electric Suit Heater system and Abyss HID lighting. While kitting

up a backup light fell into the void.never to be seen again.

With the kit checks done, I slipped into the black water, the rain pouring

like a water fall through the solid rock above, the visibility was nil near

the surface.

Descending through the darkness, I dropped to the first restriction at 30m.

At various levels, the shaft has tunnels that join it where the copper ore

vein was more closely followed. At 33m I placed my weights into one of

these "crosscut tunnels", as I didn't need additional weight below this

depth. I clipped my strobe at the cave entrance.

Dropping down to 54m on trimix 20/30, I passed the next restriction and

swapped directly to Trimix 5/76 bottom mix. It was very easy to breath so I

turned in the resistance screw on the second stages and checked all venturi

levers were set to the minus position to avoid free flows. I signalled back

to the surface with 2 pulls for OK on the descent line.

The topside cover could watch my progress on the 6 foot square black water

virtual "TV" screen in front of them. I would pull the line periodically to

indicate my progress. At 150m and 7 minutes into the dive the next big

restriction came into view, it was a solid staging platform covered in

debris. I carefully started to remove the timbers and pile them up on one

side so I could get past. At 160m and 9 minutes another pile of timbers

stopped my progress and I worked carefully to remove them, the visibility

was bad. I noticed a glow below me and was very surprised to see my lost

divelight sitting back from the main shaft, glowing brightly. My primary

light consisted a Suunto Navy 80 which was working fine and an Abyss HID

light, which proved less water tight at 130m !

At this point I did a kit and self check. I was down to 170 bar and 2 Q40

headlights had gone to sleep, my head mounted chem lights had also split

from the pressure and were all leaking green alien blood ! I checked my

twin UK SL6's and SL4 backup lights, they still worked fine. I felt no HPNS

symptoms, only a dull ache in the spine area.

I picked up the lost TEC 40 light and dropped further. The wooden floors

were coming far more often than in the shallower areas, the next one just

7m lower at 168m. This staging consisted of 2 solid diagonal timbers which

each bisected the shaft. Large timbers lay loosely on top. I removed these.

Dropping through the gap I'd made caused my twin set to get wedged on

something. I tried to pull back up but my side mounts were now below the

level and I was stuck. Visibility was almost nil, I shut my eyes to relax.

Alarm bells started ringing in the back of my mind. I was pretty much

trapped. It was time to leave at 12 mins descent time, but I could afford

another 7 min's at this depth before the deco plan using the RGBM algorithm

would be compromised.

I tried to free myself upwards, but could manage nothing. Concern flicked

across my mind, I looked at my back gas contents gauge, it showed 100 bars.

I slumped down and found my back tanks free but only going downwards. I

dropped below the restriction, down to 170m now 17 min's in and 70 bar

left. I checked my isolator valve.maybe it was off, but no luck there. I

looked up at the underneath of the floor , looking for a way through. I

moved across the shaft, and put my hand up and started to fin up, the

loose timbers lifted and with a big effort I was through. The plan called

for 147m by 20 mins. I got there early and started the deep 30 second

stops. My mind slowed down. The 15 metre END helped enormously.

The next stops trickled along, but , by 130m my back gas tanks equalised

with the surrounding pressure, and would not supply gas. I turned on my

left stage tank of Trimix 14/50. For some reason it just free flowed

violently, I put it in my mouth. Taking a breath I turned the tank off.

This tank was to be used at 90m and shallower, but needs must so I used it.

With all the excitement I forgot about the next restriction near 120m. It

wasn't much of a restriction, taken on the correct side. I ascended into

the wrong side and was wedged in to the cross timber.

On this mix, my equivalent narcosis value was 60m ish. I had a stop here

for a minute and used the time to signal to the surface I was trapped at

120m with twelve pulls of the rope. I got a response asking if I was OK. I

wasn't, and definitely needed support diver Brian to descend earlier than

planned, bringing the spare gas. There was no rope signal for this, so It

didn't happen. Id asked Brian and Christina not to attempt giving

assistance below 60m, because of the restriction dangers at this depth.

Dumping the gas from my wing and suit, I got free and headed up. With the

free flowing reg still going it didn't last as long as it should and by

100m the tank stopped breathing. I closed it and switched to my trimix

20/30. Every few breaths I would swap to my back gas to average out the

high p02. All the stops over 30 secs were reduced to 30 secs, to reduce gas

consumption, also, the planned max depth wasn't reached. By the time I

reached 60m I was ahead of schedule by almost 10 minutes, Brian wouldn't be

coming for a while. It left me

breathing whatever was left during the stops. At 60m I settled on top of

the restriction here. I dumped all my wing gas and replaced it with exhaled

trimix 20/30, this might be useful.soon !

Brian showed up by the time I got to 40m. I ascended up with him still

breathing my 20/30 and back gas till 21metres. The first tank on a rope

appeared at 21m it was nitrox 50. This stop at 21m I increased from 6

minutes to 40 minutes, an ounce of prevention here could save some trouble

later on. During this stop Brian went up and Christina came down with some

more nitrox 50. The rest of the stops went to schedule. The warm drinks she

brought down with her were very welcome.

At 6 metres I moved onto oxygen for 30 minutes, then 4 metres for 20

minutes and 3 metres for a further 30 minutes, every 15 minutes I would

have an airbreak for 5 minutes. I chose back gas switching here but this

was a mistake because of the really hypoxic trimix 5/76, after just 2

minutes of breathing this, I felt my brain and vision shutting down, so it

was quickly back to the oxygen. The further air breaks I used some trimix

20/30 (the theories behind this, attempt to prevent Pulmonary related

decompression problems and not simply buffering the CNS clock). A further

ten minutes at 2m and ten minutes at 1m served to relax my bodies gas

tissue tensions, a useful technique id used before when forced to deco on

back gas etc.

After all this extra deco, I felt confident that the bends were not coming.

With all the extra deco stops, it meant close on 200 minutes in the cold

water. I was still warm and dry, my drysuit worked perfectly. I had spoken

with Otter a couple of weeks before and they mentioned a new Artic 300

under suit. I got one of these and was very pleased I did. My support

divers had mere mortal under suits and felt the cold pretty much


Using the RGBM algorithm on this dive was totally in order, but in a low

gas situation would be easy to compromise. The RGBM deep stops necessary to

allow shorter shallower stops are mandatory. To have missed out any of the

deep stops would radically increase the decompression schedule. When

carrying out any Accelerated decompression profile such as this it is

necessary to have a back up "traditional" profile and make provisions for

the extra breathing gas that would be needed.

While I'm a proponent of helium being very much easier to off gas than

nitrogen, I feel that proving myself wrong means the bends, hence the

increased 21m stop time to offset the decompressing between 40m and 21m on

incorrect gases.

In the past I have willingly tested algorithms on myself, but see no

reasons to do this now or in the future, unless in the relative safety of a

research chamber.

Readers with a Central Nervous System Oxygen Toxicity calculator would see

that my "CNS" loadings from this profile were over 200%. Measures were in

place to deal with the possible side effects. Minimally, I believe, all

technical divers should abstain from any "diet" products for at least a

month, be they drinks or foods. Artificial sweeteners are known to be

massive CNS exciters.

Technical dives should be attempted by people on a "level playing field ".

Divers should be fit, regularly doing aerobic exercise. They should avoid

cigarettes/alcohol for months before a deeper dive and have no history of drug

abuse. If a technical diver benefits from diet fizzy drinks then they

should exercise until they don't!

I would still like to explore this mine shaft deeper, but any further deep

dives will need several clean up dives in the 170m range. The reasons for

doing these deep dives are mostly for the exploration and adventure.

Another reason is to improve my teaching ability as a Trimix instructor

trainer, how any instructor can teach without doing it themselves baffles

me. The experience and knowledge gained from these dives is invaluable.

I would like to thank Christina and Brian for their help and time. Also

thanks to the International Technical Diving Association at Fort William,

Scotland for the donation of all the diving gases. Thanks to Kent

Engineering for the supply of the sexy stainless exploration reels used,

finally Otter dry suit's for the loan of the electric suit heater system

and thermal advice.

Contact emails
Otter drysuits : (drysuits)


Kent Engineering : (cave/wreck reels) (software and tech wings)

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