Read original article at 112.ua
In early May, the hot topics for the media were statements of numerous officials about the dangers that threaten Donbas due to the flooding of mines located in the uncontrolled territory.
The Minister for Temporary Occupied Territories of Ukraine, Vadym Chernysh, noted that the water level in the flooded mines on the territory controlled by self-proclaimed DNR and LNR republics is critical and almost reached the maximum permissible level.
Vice Speaker of the Verkhovna Rada of Ukraine Iryna Herashchenko complained that it is impossible to conduct a normal monitoring of the situation at enterprises, as this is hampered by the "authorities" of the self-proclaimed "republics", although Ukraine's international partners in Normandy format are ready to assist in preventing the disaster.
In turn, the representatives of the self-proclaimed LNR and DNR declared the deterioration of the environmental situation as the fault of Ukraine and demanded to let their "inspectors" to visit Ukrainian enterprises of Donbas to check them.
As a result, the theme of ecology was discussed on May 15 in Minsk at a meeting of the contact group of Donbas conflict settlement. After that, the conversations ceased, but the danger did not disappear.
In blink of an eye the earth opened up
First a bit of history.
In 2014, in the Perm region of Russian Federation, literally an enormous landslide absorbed a part of the village. The trees and houses fell into the abyss. And only by some miracle there were no people in the place of landslide.
The reason for the accident was the flooding of Uralkaliy enterprise mine. Despite the hydro-cladding system and the powerful clay beds that protected the salt from the penetration of water, the extraction of salt on an industrial scale created cracks through which water began to penetrate underground cavities, voids and accumulate between layers of rocks. As a result of erosion of weak rocks underground lakes were formed in the layers of clay. At some point, they washed their way out in the operating mine. There was a flood. Already two days after the flooding of the mine, a dip of the soil occurred at a distance of almost 4 km from it, that is, the water per day washed its way 4 km to old abandoned workings place of mine and united them into a large cavity, which led to collapse. In just three months, the landslide area increased fourfold.
Also at the time of primary flooding, incidents of landslide were reported in other regions 5-10 km from the mine.
This is not the first accident in places of salt extraction. In 1995 in Solikamsk a pit with a depth of more than 4 meters and area of 950 by 750 square meters was formed in a few seconds.
Similar accidents happened in other countries. For example, in the United States in 1980, a crack in the salt layer led to the fact that the water from the nearby Pener Lake found its way to the mine in Louisiana. Finding the way, the water instantly made a pit, and even a few fishing schooners were sucked into the hole.
Why does this happen? It's all about the physical characteristics of salt, which is a very strong mineral, capable of withstanding enormous loads, but only under the condition of a completely dry state. Water, even in a small volume, is able to wash out huge cavities in the salt layers, which naturally destroys their integrity.
In the Donetsk region there is Ukrainian Solikamsk - the city of Soledar, in the vicinity of which salt was also mined from time immemorial times and on a completely different scale. Over the centuries of salt mining cavities-voids of 30-35 m in height were formed under the city.
They are not unfastened in any way, that is, salt keeps itself. In the salt layer, the thickness of which is 40-50 m, the equipment took out the middle in 30 m high. And that's all. The width of the notch is usually 14-15 m, and then workers leave it and started working near it in another place. Salt pillars and 10-meters thick roof of salt on them are keeping 300 m of soil over them, not to mention the city above, which crowns this layered cake like a cherry. The total length of the excavations is already over 200 km.
As a result, the area of emptiness beneath the city is much larger than the city itself, and Soledar now resembles a sort of "flying island": it hovers on a salt cushion above the mines that are formed as a result of years of salt production. And according to experts, already over 280 million tons of salt were extracted.
The volume of cavity below the city is more than 110 million cubic meters. If you imagine an average two-room apartment and its expanses, then in the space from Soledar to Bakhmut one million of such apartments can easily fit. Or how they like to repeat at the Artyomsol enterprise, the amount of salt extracted from the ground is already more than forty pyramids of Cheops. And this volume is much larger than the size of the city itself and the surrounding villages. Moreover, these cavities, like in the real pyramids, are also connected by the holes between themselves.
It's terrible to imagine what the water penetrated into such a "pyramid" can do, but meanwhile it is quite real, and for a long time already.
Donetsk ridge and flooded mines - a deadly combination
There is a so-called Donetsk ridge in Donbas - a strip of elevations up to 370 m high, stretching from north to south in the middle of Donetsk and Luhansk regions. And it happened so that the line of demarcation literally repeats the geological bend of the Donetsk ridge. And the territories under Ukraine's control are 100-150 meters below the ATO zone, and the cities of Bakhmut and Soledar are literally on the line of delineation of the ATO zone, 30-35 km from the line of active combat clashes.
For example, Soledar lies at an altitude of only 100 m higher from sea level, while neighboring cities are located 120-200 m higher, that is, if there is a clump of groundwater beneath these cities, all this liquid may flow downward according to the slope - to Soledar.
Next to Soledar and Bakhmut there is Horlivka, located on the main anticline of Donbas - on its summit at an altitude of 295-310 m above sea level. All rocks lie at a steep angle from Gorlovka, like wings in different directions.
All Horlivka mines are flooded today, but as neighboring cities lie lower, the water here will never come to the surface, and together with groundwater and water from natural precipitation it will flow from Gorlovka in the direction of falling beds, forming underground rivers.
The decline of one wing begins from the Gagarin mine in Toretsk direction, and exactly from this city the so-called Toretsk hollow begins, the decline of the second wing stretches from Yenakiyevo to Kirovsk and both wings drain water into the so-called Bakhmut hollow, over which the cities of Bakhmut and Soledar are located, with the salt cavities of tens meters in height under them.
It turns out that underground waters from the flooded mines of Horlivka and Toretsk are now seeping into Bakhmut, where the chalky rocks and gypsum, which also become softer because of the water, are washed out and flow further to Soledar. Bakhmut has many cavities: left after salt extraction, the production of gypsum and chalk. In the cretaceous beds that there are karst voids, capable of forming underground lakes, accumulating water for a long time.
On the other side of this hollow the cities of Yenakiyevo and Kirovsk are located, which mines, due to fighting in the ATO zone, were also flooded. And again, the water from them will seep to Soledar, as the fall of rocks leads precisely in this direction, and they are both 100 m higher than Ukrainian Solikamsk.
All the mines in Horlivka and Yenakiyevo, and there are more than a dozen of them, are stopped today, there is practically no pumping out of the water, and as a result, hundreds of kilometers of excavations and voids left after coal mining are gradually filling with water, so now we don’t know what level is already flooded. But Horlivka stands on the top of the anticline, even accumulated water constantly flows down: the underground waters "go" to the Toretsk and Bakhmut basins along the layers, and the near-surface and subsoil waters – directly to Bakhmut.
In Horlivka, the mines on average have a depth of 1000-1100 m, while Soledar's salt mines have a depth of 300 m. After flooding in Horlivka at the level of 250 m, the mine waters will flow to Soledar.
Salt is a very strong mineral, salt pillars hold dozens of square kilometers of Bakhmut and Soledar on themselves, but in front of water they are powerless. The accumulation of water leads to the formation of underground rivers, and the latter naturally flow along the slope, which is directed towards the Bakhmut basin. Salt pillars in the underground river will stand for several hours. It is not known how much water is already accumulated and how many excavations are already washed away.
In the Perm region near Solikamsk no one imagined the possibility of a landslide, and it became a complete surprise, but there the volumes of mining and excavations were hundreds of times smaller. And on the surface there was an empty and abandoned village. Over the Bakhmut basin there are many settlements and two fairly large cities - Bakhmut and Soledar, and in total more than 100 thousand people now live above the hollows of salt mines. The scale of a possible tragedy could be incredible.