Oil shale mines of the Leningrad region are characterized by a complex structural structure of the promplast of the working capacity of 1.5-1.6 m (including three layers of oil shale with a total thickness of 1.0-1.05 m and two interlayers of limestone), low thickness of individual layers of oil shale, significant karst in the host rock strata, high inflows of groundwater, etc. ...
