Technically Speaking: Diving the Mountain

Australian cave divers have a number of old coal and gold mines scattered through out the country, including in NSW, where we have a few examples which have been abandoned long a go and forgotten. A handful of Sydney Project cave divers ventured out to the Blue Mountains to explore one of NSWs abandoned mines.

Some of these mines may not be accessible for various reasons such as being located on private properties and owners sometimes reluctant to allow access - especially when it involves diving.

On the flip side to that are property owners who have become to curious to know what’s down there; welcoming the idea of some crazy people going down that dark dirty hole in the ground!

One such place is an old coal mine west of Sydney which is part of the Illawarra coal seam. The mine opened during 1920’s and with 24 miners working, produced shale coal between 1923 and 1926.

The biggest challenge the miners had was supplying electric power to the mine and the second was pumping out water that was always seeping through the rock. It was an expensive exercise to keep the mine open, and it eventually closed after just 3 years of operation. The reason for the closure is not totally clear, but most likely financial, because the coal quality was poor.

Prior to venturing first time to dive a mine, it is prudent to complete as much historical research as possible on the site. Mines can be very dangerous places after they flood, especially older sites. Structures are known to become very unstable and cave-ins become a major concern.

The mine we decided to venture into is located in bushland with little access so the first task was locating the entry to the mine – not an easy task when it’s covered in thick bush.  We soon reaslised though, as we lugged our gear through the scrub, that a 4WD was probably a better option upon our next visit back to this site.

But since we where there already, we decided to make a quick check out dive. The entry to the mine required a walk down a 15-degree slope for 800 metres from our vehicles. After three trips up and down the mountain with rebreathers, video camera and the rest of the gear, we felt like we did a marathon!

The water level in this mine is 200 metres below the surface with 200 metres of dry tunnel to walk through before reaching the water. The ceiling in the dry section is just high enough for a short person, so for a person of average hight really needs to hunch down when walking through. The process of carrying gear with little ceiling height is tough on your legs.

Though initially the water at first appeared to be very clear as soon as we entered the water, our movements in the water disturbed 90 years of algae growth, this turned our clear visibility very quickly into zero visibility.

Even the most careful fin stroke could not avoid dislodging algae from the ceiling and on every other structure in the tunnel. But the good news was as we found out later, that once this algae fallen to the floor of the mine, they were not an issue anymore. The bad part is that all new sections we explore, means we have to put up with bad visibility. Though coming back is now much better, with clear water until the last few metres, which is always zero visibility, and makes for interesting deco trying to read gauges!

The main tunnel runs down at a constant 15-degree angle providing a constant depth increase. The main tunnel runs for the first 30 metres to a depth of around 10 metres, which then splits in two by a partition wall. There is also a ventilation shaft on the right that is filled with organic matter from trees. Tree roots can be seen penetrating the ceiling providing a perfect environment for yabbies.

The main tunnel continues to widen, and the partition wall made of wood, isolates the coal carts from miners for safety. Rail tracks are still visible under thick layers of silt.

The silt covers everything in the mine, and most of the wooden structures, even big support columns for the ceiling are very unstable.  On the first dive after reaching about 30 metres of depth and a distance of around 150 metres into the mine, I was following Paul Garske with my camera in hand, and it was so dirty that I only knew where Paul was by him kicking me in my face with his fins. Then when doing some short deco, I felt big chunks of shale rock fall on my head, with pieces getting stuck behind my head and the rebreather! Lesson one learned “Don’t rest your fins on the ceiling” and always wear a helmet.

The first dive was exciting because it showed that the mine is big and with, potentially, plenty of tunnels to explore.

Following this initial dive, four more visits had uncovered more of the mine to a depth of 55 metres, and at a distance to 400 metres. The most exciting dive was when Dave Apperley found the coal cart but with the news that it blocked the way further.

The next dive I followed Dave’s line to the cart to what I initially though was a small little box on rails, but how wrong was I? When I approached this huge cart that was nearly as high as the ceiling! I attempted to squeeze past it next to the partition wall, but it was too tight, visibility was zero and my deco obligation was now building up. The worst part was I saw not just one cart but also at least another 4 in line! I decided to re-think the approach on a later dive.

Visibility on the way back remained good until the last 7 metres, where it always zero. To read you computer, you need to put it right on your mask, and play with light angle from a small light source just to see the numbers. The water is just 12c.

On the next trip to the mine I decided to try and remove one stage cylinder, to make my profile narrower. Though as per Murphy’s Law, Dave developed a problem with his gear, and wasn’t going to be able to assist in this push, so I decided to look around the cart area for other access points beyond them. For whatever reason, none of us looked on the left side of the tunnel, and to my surprise I found that the tunnel looks to have been excavated wider, with big black void in the distance. With a smile on my face I reeled out a short distance only to see what appeared to be another tunnel on the left wall! With this I decided that going past the carts had to wait in order to explore this tunnel, which turned up to be just a small room at 4 metres into the wall. With algae killing all visibility again in this new area, I decided to turn the dive, but knowing happily that there is a way further on past those carts.

On the way back I found a teacup and old style beer bottle, just to remind you of those miners that worked in this harsh environment. But now we have the privilege to re-trace their steps in this rather unique place.

As I mentioned earlier diving in mines is dangerous, and only the most competent, experienced cave trained divers should attempt to enter them. This is not a natural made environment, and was never meant to be stable underwater.

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