Iron ore had been exploited from the mine near Beroun from 1861. The last miners went up in 1965. The mine has 84 underground floors and reaches a depth of 426 m.
David M. and Jirka K. have been diving in Chrustenice since 2001. However, the work at a depth of more than 100 m in the cave environment requires an experienced team of divers. Consequently originated Project BAT1.
A mining exhibition gives access to some dry sections on the seventh and eighth floors. Visitors can take a mine train along almost half a kilometer during sight-seeing. They take a look round the mine and can see usable logging technology.
The lower floors are flooded and available only to divers. There are two underwater entry parts. The first one is an old shaft with a 45 degree at slope named Alfa. It should end at 140 m under the surface but the access is blocked at this depth by impenetrable caving of roundwood, planks, mud and ruined pieces of rocks at 112 m. Alfa intersects the 16th floor (at 41 m) and the exploratory team of the BAT1 project first established and documented an even connection of the 24th floor at 88 m.
The second shaft, trailing, with only a 14 degree slope, is named Beta. The entry is complicated by zero visibility at the surface. Her total length is 967 m. There is a roof fall which needs a 620m swim.
Diving in flooded works to 100 m is far beyond the limits of regular diving. Trimix is used and a range of decompression mixtures during the ascent. The serious work – accessing, security, documentation, mapping, filming – this all demands a long bottom time.
The exploratory team – David and Jiri use a Halcyon RB 80 semiclosed rebreathers.
The procedures are based on DIR methodology which has proven itself as safe during the biggest underground explorations projects in the world, for example WKPP or EKPP.
Dry support is also very important.
At present there are more than ten divers working on the BAT1 Project. Dives to 100 m depth with long bottom times are doing Jirka and David.
The others work as a support team and dive in relatively less depth but most of the dives require Trimix and stage for decompression.
Securing the underwater areas began during the summer. The logistic background was built in the dry part. The cabelway for transporting materials was installed in Alfa shaft. A habitat was planned and will be installed shorten. Using the habitat allows divers to spend several hours on oxygen decompression after difficult deep dives in relative comfort, warmth and safety. Rather chaotic existing system main lines will be compeletely reinstalled. New lines have been installed to the new exploration areas.
The documentation of connection 24th floor at 88 m depth, the state of caving at 112 m in Alfa and the part caving at 90 m in Beta has started. This will theoreticaly opens the way for penetration to deeper floors. Flooded tunnels leads to depth more than 300 m.
The great cooperation with CMA, The Association For Exploration Historical Underground, is good condition to success. The Project BAT 1 will bring the information about the state of flooded area of the mine with the visual documentation for the exhibition. CMA permits an exclusive access and the installation required engineering. Even mining railway, which is needed for transport diving equipment, is available for the Project.
Apart from the main shaft, the exploration of the hall system, where noone has not been yet, has been still waiting for the members of the Project after building up the hinterland. This includes even the exploration of the hydrologic conditions, collecting samples of the water to analyse, the analasys of the risk. The documentary film has been filming about this all.
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