The Head of the Federal Environmental, Industrial and Nuclear Supervision Service of Russia (Rostechnadzor) Alexey Aleshin and the President of ALROSA Sergey Ivanov met on November 10, 2017. The subject of the meeting was the completion of the investigation by Rostechnadzor of the accident at Mir mine on August 4, 2017.
After the accident that took the lives of eight people in the flooded mine, the head of Rostechnadzor ordered to establish a commission to carry out a technical investigation into the causes of the incident. To obtain an expert opinion, four expert groups were formed from leading Russian specialists and scientists.
The commission concluded that the accident was caused by a combination of hydrogeological, technical and organizational factors. One of the main reasons was the anomalous hydrogeological complexity of the deposit conditioned by a system of unfavorably underlying cracks in the structural fault.
Among the technical reasons, the commission listed a number of adopted design decisions. In particular, the project of ‘dry conservation’ of the open-pit mine implemented in the early 2000s did not take into account the possibility of washing out of ore and rocks. It did not provide for a long-term performance of the pumps installed at the bottom of the open pit for pumping out incoming water. The technological regulations and development projects contained no technology for backfilling of washouts in the mine workings. The storage of salt on the open pit edge contributed to the early failure of water-circulation galleries of the ‘dry conservation’ system.
The commission also reported that hydrogeological observations were conducted within the ore body only, and the project did not provide for the monitoring of brine inflows. This led to the unreliable assessment of the changed hydrogeological situation at the open-pit mine.
It should be noted that the conditions that resulted in the accident did not emerge abruptly, it took them several years to develop. ALROSA experts observed no signs of an emergency. The monitoring system did not predict the emergency either. Today, there are no reliable control systems in Russia and abroad that can make it possible to identify the development of cavity formations in rocks.
The commission developed organizational and technical measures to localize and eliminate the causes of the accident, and identified 16 officials responsible for the violations that led to the accident. According to the Company’s order, ALROSA’s management must determine the complete list of persons and their personal responsibility for the accident.
The operation of the mine is stopped. The commission estimated the economic damage at RUB 10.216 billion.