Central Europe experienced catastrophic rainfalls and flooding in 2010. This paper discusses a decommissioned shaft that was flooded by surface water, which led to displacement of shaft backfill and an inrush of large amounts of water into an underground pumping station. The weather conditions for the period preceding the inrush, the hydrogeological conditions, the quantity of water that entered the mine dewatering systems, and the underground hydraulic connections are all described. Uncontrolled inflow of water as a cause of backfill saturation and the hazard for active underground infrastructure were analysed. A need to rebuild damaged infrastructure was identified. The case study highlights the need to improve underground mine closure requirements to ensure safe conditions above ground, particularly in densely populated areas.

Water wells play an increasingly important role in providing water for the civilian population all over the world. Like other engineering structures, wells are subject to ageing processes resulting in degradation, which is observed as a reduction in hydraulic efficiency throughout their lifespan. To date, it has been found that the ageing process of a well is determined by a number of factors. The mathematical description of this process can be simplified. Drawing on Jacob’s equation, this paper presents the course of the degradation process as a variable depending on operation time, well loss and flow rate. To apply the determined relationships in practice, simplifying assumptions were adopted, which make it possible to determine the moment of ageing compensations of the degradation processes. It was also demonstrated that the degradation process may be slowed down by the appropriate selection of initial operating parameters. The presented discussion highlights the significance of parameters α, δ and exponent β. The relation between hydraulic resistances in an aquifer and in the engineering structure is closely connected with these values. The presented arguments indicate that step drawdown tests provide the necessary information which allows tracking changes in the ageing processes occurring in the engineering structure. The analysis of the drawdown test results makes it possible to determine the moment when the necessary adjustments in the operating parameters of a water well should be performed. Eventually, it allows maintaining the high hydraulic efficiency of the intake and extending the lifespan of the well in accordance with the principle of sustainability.

Drainage wells used in lignite mining have to be operated at high efficiency in order to achieve a targeted drawdown in the shortest time period possible. However, oversizing of pump units and excessive pumping can cause accelerated aging of wells and over time, decrease a well's drainage efficiency. This article analyzes the case of a well that was operated for 10 years and then abandoned at a lignite mine. A common practice in installing dewatering wells in Poland is to protect the well screen with a prefabricated granular layer (called a ''gravel coat'') that is attached to the screen when it is lowered into the hole. The combination of the gravel coat and well screen is surrounded by a protective gravel pack. Samples of the gravel coat were obtained from the abandoned well. The percentage by weight of precipitates in, and the porosity of the gravel coat from the abandoned well were determined and compared with the properties of new gravel coat material. Tests were conducted in the laboratory to compare hydraulic losses, apparent seepage velocity, effective velocity, and the hydraulic efficiency of the well's gravel coat. The results of the tests explain the low hydraulic efficiency of the abandoned well and the origin of the damage to the gravel coat. The actual yield was also compared with the calculated theoretical safe yield, which was estimated based on the results of geological records from the construction of the well.

W artykule podjęto próbę rozwiązania problemu dotyczącego interpretacji wyników opierających się na porównaniu wartości zmierzonych do wartości dopuszczalnych. W przypadku zaobserwowania przekroczeń, u osób będących odbiorcą analiz akustycznych (głównie osoby niespecjalistyczne), bardzo często pojawia się niepewność związana z interpretacją wyników. Obecnie brak jest jednoznacznego sposobu określania w przypadku hałasu, przedziałów wartości akceptowalnych, niepokojących, czy niedopuszczalnych. Zaproponowano autorską metodykę wskaźnikową, umożliwiającą w jasny i łatwy sposób, interpretację uzyskanych wyników. Zaproponowany wskaźnik obciążenia hałasem (NLF – ang. Noise Load Factor), oparty na mierzonych wielkościach fizycznych, umożliwia przeprowadzenie szerszej oceny uciążliwości akustycznej pochodzącej od pojazdów kolejowych. Słowa kluczowe: hałas, ocena oddziaływań na środowisko, oddziaływania akustyczne