Groundwater sampling from borehole KR6 during long-term pumping test at olkiluoto, Eurajoki in 2002

A long-term pumping test from borehole KR6 at Olkiluoto was initiated in 2001. Both flow and in situ EC measurements as well as groundwater samplings from specific sections are being performed. The aim is to get information on the potential connections via fractures both to the sea and to the deep saline groundwater during long term pumping of the borehole. In 2002 and at the beginning of 2003 six groundwater samples were collected from borehole KR6 at three different sampling depths (98,5-100,5 m, 125-130 m and 135-137 m). Groundwater samples were taken from the packed-off sections by a membrane pump. Salinities of two groundwater samples from depths 98,5-100,5 m and 135-137 m were increasing due to the long term pumping of the borehole KR6. Whereas the salinity of the groundwater samples taken from section 125-130 m was decreasing between two groundwater samplings done in 2002. All taken groundwater samples represent water type Na-Ca-Cl and they are brackish (1 000 mg/l <TDS< 10 000 mg/l). Electrical conductivity, which was measured during the groundwater sampling, was compared to the in situ electrical conductivity measurements. The results achieved with different methods agreed well except for one sample. Based on EC results it can be concluded that groundwater samples taken from borehole KR6 represent good groundwater from a single fracture or narrow fracture zone. This study presents sampling methods and the results of analyses of groundwater samples from the deep borehole KR6. Beside these the report presents operating principles of the in situ EC measurements and also comparison of the results to the EC results measured during groundwater sampling. This report also contains a short comparison of the groundwater sampling results achieved in 2002 and 2003. (orig.)