## 3 Results  
### Pollution Level in Groundwater Due to Localization of Piezometers  
Based on the monitoring studies, the most vulnerable to contamination were the areas closest to the landfill (0.5 km zone), mainly to the northwest and southwest. Monitoring results from piezometer P-2A, located at the outflow on the eastern slope of the landfill, indicate significant changes in the levels of pollution indicators, in particular caused by organic waste storage. Slight increase of the TOC level observed in this piezometer may be a result of its localization in a forest area. A similar trend in the TOC level, caused by forest surroundings, was also noted in piezometer P-4. Monitoring results from piezometer P-6A, localized in a local depression with periodically stagnant water on the surface, show pollution concentrations exceeding the acceptable values for the third water quality class. Exceeded values primarily refer to the TOC level, which can be regarded as typical of a forest area. For piezometer P-7A, the most visible changes concern the COD level. Exceeded values of this parameter result from its localization in an overgrown area. A similar trend in the COD level changes is observed for the monitoring results from piezometer P-9, which is very much dependent on the putrefaction of vegetal remnants along the railway siding situated near to this piezometer. In the case of piezometer P-9, the fluctuations of some pollutant concentrations (for example the TOC level) also result from its localization. Particular influence on the concentration of selected pollution indicators has the nearest area where the production and service facilities are situated. Higher concentration levels of contaminants in piezometer P-11A result from a local depression where the piezometer is located. Because of this, water from the railway siding and the composting area can flow down easily to that point and directly cause groundwater pollution in this piezometer. Fluctuations in the concentrations of pollution indicators (especially TOC) and exceeded standards for the third class of groundwater quality were also observed in piezometer P-12. The main reason for this is runoff of contaminants from the composting plant area. Groundwater in piezometer P-14A meets the standards for the third class of water quality. Only periodic fluctuations in TOC and COD concentrations may result from seasonal changes of groundwater level, which means that increased values of these parameters correspond to lower groundwater levels. Apart from the sporadic excesses above reference values, the TOC and COD concentrations in groundwater from piezometer P-15 located in the area of the MBT installation comply with Polish standards. Seasonal fluctuations of these indicators can be attributed to runoff from the compostory plant and seasonal changes of groundwater level. Seasonal changes in pollution indicator levels observed in groundwater from piezometer P-17 are determined mainly by runoff of contaminants from Estrady St. and the industrial facilities located nearby. Based on the obtained results, it can be concluded that the concentrations of the analyzed parameters have decreased with the distance from the landfill, which can be linked to biodegradation and dilution. A similar trend proving that concentrations of contaminants in groundwater decrease with increased distance from the pollution source was presented by [PERSON] and [PERSON] [23], [PERSON] et al. [36] and [PERSON] et al. [37]. Regarding the influence of precipitation on contaminant concentration we can also claim that the concentrations are linked to the groundwater level which is mainly supplied by rainfall. According to groundwater level monitoring data (not presented in this article) it is noted that groundwater level in all piezometers show seasonal pattern. It should be noted that in accordance to high precipitation and resulting from this high groundwater level, lower concentration of indicators are observed.