The change analysis of filtration parameters and chemical composition in trakai wellfield

The wellfield in Trakai became operational in 2009. However, when supply of drinking water to Lentvaris city stared (in 2016, February), the physical properties of groundwater worsen and the concentration of organic materials started to increase. The aim of this bachelor thesis – evaluate the geofiltration parameters of reconnaissance groundwater layers and chemical composition in Trakai wellfield and indicate solutions of water quality improvement. Groundwater horizon is in the bottom part of quaternary layers, which is formed of upper Nemunas – Žemaitija (III –II nm3 – žm) sediments. Filtration coefficient of these sediments ranges between 8,4 and 23,0 m/d; transmissivity coefficient ranges from 159 m2/d to 437 m2/d, calculated using Theis equation. Transmissivity coefficient ranges between 217 m2/d and 473 m2/d (by Cooper and Jacob method). The yield in well no. 62328 is 549,60 m3/d; in well no. 63934 – 1192,80 m3/d. Groundwater that is found in upper silurian layer, has high water quality: the filtration coefficient is 0,4 m/d, meanwhile, transmissivity coefficient ranges from 4 m2/d to 8 m2/d. The yield in well no. 63867 is 300,00 m3/d. The calcium magnesium carbonate type groundwater is extracted in Trakai wellfield