Browsing by Author "Jalava, Linda"

University of Helsinki, precisely the Department of Geology and Geography installed a groundwater station on Lammi Biological Station, to be used for academic research and education purposes. The main principle of this study was to collect basic properties of the soil and groundwater circumstances on the site and to test the main functions of the groundwater station. The groundwater station includes six groundwater monitoring wells, installed in January 2015. To describe the groundwater circumstances as widely as possible, the wells were installed on places where groundwater both recharges and discharges. Soil samples were collected and a field estimation of the layer order was made during the installation of the wells. Grain size distribution and hydraulic conductivity were defined in the laboratory and multiple other hydraulic conductivity measurements of the soil were made in the field. Also groundwater samples were collected and the chemical composition of the water examined. Besides elevated concentration of iron, manganese and uranium the quality of the groundwater was good. pH-values were close to neutral, alkalinity normal and electrical conductivity low. There was a regional variation in the quality. Continuous measurement devices were installed to the monitoring wells in June 2015, to follow the temperature, groundwater level and in one of the wells electrical conductivity. This data was followed from the early summer to the next spring, to receive versatile data due to climate factors. Groundwater level seems to react to the amount of precipitation. Similar variation pattern were noticed in the groundwater levels in all of the wells. An estimation of groundwater table, bedrock surface and soil thickness were made using data from this and the earlier studies. The soil on the site consists for the most of stony sand till overlaid by 1 – 4 meter thick layer of fine sediment. The hydraulic conductivity and grain size distribution of till variated largely even in the same spot. The hydraulic conductivity variated between 4,8 * 10-6 – 1,0 * 10-1 ms-1, normal values from silt to gravel. The groundwater table is situated without exception in the till layer, thus its thickness and depth variates regionally. The site was divided in two zones based on the contours, field observations and old and new drilling data.