At quarries in the Leningrad region, granite breaking is conducted, placing explosive charges in vertical wells with a diameter of 105 mm. Usually after explosions the floor of a bench turns out extremely uneven, protrusions (sills) sometimes reach one third of the height of the bench. Due to the uneven floor of the bench, the productivity of excavators EKG-4 does not exceed 250 thousand m³/year, i.e. about half as much as at leading mining enterprises