In 2002 the study of the impact of coal mine methane leakage (in November 2000) due to the damage of underground gaspipe (63 PE) was undertaken. The properties of soils, plant cover conditions and the composition of groundwater on the area of allotment garden in Włocławek was studied. For the investigation soils were sampled from the following depths: 0-20, 20-40, 60-80 and 100-120 cm of 8 bore-holes; groundwater and plant material (thuja needles) from these sites were sampled, too. The present state of the soil environment was estimated on the base of indirect indices, which reflect two year impact of the excess of methane: the pH of soils, total sulphur contents, redox properties of soils and the activity of dehydrogenase. It was observed that methane leaking unsettled the dynamic equilibrium in gaseous phase of soil. The increase of methane content caused the reductive condition in soil and disturbed its microbial and enzymatic activities. The deficit of oxygen caused negative effect on thuja plants and their complete damage in extreme sites. The study showed also still high content of methane and tetrahydrothiophene in groundwater.