Workreport 2018-29



Quality Assessment of Transmissivity Data Acquired Over Time in Surface Drillholes at the Olkiluoto Site


Aalto, P., Ahokas, H., Hurmerinta, E., Komulainen, J., Pentti, E., Tammisto, E., Vaittinen, T.



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This report presents fracture-specific transmissivity and position data from surface-based drillholes in Olkiluoto, gathered over more than a decade of site investigations and monitoring related to the construction of a geological repository for spent nuclear fuel. The information is necessary for understanding and predicting groundwater flow in the bedrock, which in turn is a key factor for the planning, performance and long-term safety of the repository. The presented dataset of almost 3,900 fractures intersecting drillholes OL-KR1–KR57 and adjacent OL-KRB holes is based on measurements carried out before 2013 by three main investigation methods: Posiva Flow Logging (PFL), Hydraulic Testing Unit (HTU) and long-term pumping tests. In most drillholes, several measurements using one or more of these methods have been made, sometimes with remarkably different results. Therefore, the compilation of a dataset of the most representative fracture transmissivities requires comparison of different results and the assessment of factors causing the differences. In this work, the largest transmissivity obtained by the PFL method for each water-conductive fracture has been the starting point and, in the majority of cases, that has been chosen as the final value.


Transmissivity, hydrology, hydrogeology, final deposition


WR 2018-29_web (pdf) (16.3 MB)


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