In the Ukrainian city of Kalush (Ivano-Frankiv region) since 1967 until 2005 there was an open pit "Dąbrowski". It exploited potassium. Until 2008 the drainage system functioned. It consisted of the ditch to channel the water outflow from the Quaternary layers and collected brine in the exploited southern part of the mine. In January 2008 the drainage stopped due to bankruptcy of the enterprise. The pit was getting flooded. In July 2008, during a heavy rain, the inundation rapidly accelerated and became irreversible. In the place of the pit a lake was formed, which has already accumulated over 20 mln m 3 of brine. Over the inundation of the pit there is a fierce discussion on its environmental impact. The authors of article [1] stated that the deformations of scarps would be so great that the hole would reach the canal located in the distance of above 200 m from the northern scarp of the mine. Another probable threat is the salinization of rivers and the Quaternary water-bearing horizon, used as the source of water to be supplied to the residents. The opposite opinion is represented by A.M. Gaydin, which in article [2], based on physical modelling and theoretical calculations, proved that the damage to scarps would not exceed 30-40 m, and the upper part of the water horizon in the future lake would not be saline, thus there would be no threat to the environment. It has been almost five years since the beginning of the inundation of the mine and these predictions were confirmed by direct observations.

Providing a long durability of the historic salt mine of Bochnia demands proper observations, analyses and drawing conclusions based on them and leading to recognising and the assessment of a specific behaviour of the rock mass and the effectiveness of the protection from mining damage. The studies of the rock mass and surface deformation are carried out by the mine based on the results of the observations made with the methods of surveying. These observations include, among others, the measurements of the height of benchmarks stabilized on the surface and rock mass, the measurements of linear convergence (on the established vertical and horizontal bases in selected chambers of the mine); and since 2003 the attempts have been made to apply total stations and laser scanners to document the selected chambers. The article presents test studies on laser scanning carried out in the chapel of St. Kinga in the Bochnia Salt Mine in 2007 and 2013 (Fig. 1). They showed high accuracy of the scanning method both in the positioning of points of the salt excavation, in modelling, as well as calculation of the area of any cross-section (Fig. 2) and the volume of chambers of complicated shapes (Fig. 3). The carried out accuracy studies, analyses and comparisons were used in the calculation of the area convergence for the chapel of St. Kinga in the Bochnia Salt Mine. They make base for the calculation of volume do convergence in the near future.

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Geodetic methods of examining the ef ciency of security measures in the old workings of historic salt mines (focus on the "Wieliczka" Salt Mine