INTERUNIVERSITY PROGRAMME MASTER OF SCIENCE IN PHYSICAL LAND RESOURCES Universiteit Gent Vrije Universiteit Brussel Belgium Integration of detailed borehole core measurements and pump test data from the aquifers below the Boom Clay in the groundwater flow model June 2014 Promoter: Master dissertation in partial fulfilment Prof. Dr. ir. Marijke Huysmans of the requirements for the Degree of Master of Science in Mentors: Physical Land Resources Dr. Bart Rogiers by: George Bennett Dr. Katrijn Vandersteen i Acknowledgement First I would like to thank the Belgian Nuclear Research Centre, SCK•CEN for giving me the opportunity to perform this master thesis. Secondly, I wish to thank my promoter Prof. Dr. ir. Marijke Huysmans, my mentors Dr. Bart Rogiers and Dr. Katrijn Vandersteen for their continuing support and constructive contributions to this research. I also like to thank Ms. Lisa Potums, who helped me in the characterization of the borehole cores with a handheld air permeameter. Finally, I wish to thank my parents for their support and encouragement throughout my study. ii Abstract For more than three decades now, the Belgian Nuclear Research Centre (SCK•CEN) has been investigating the possibility of using the Boom Clay in north-eastern Belgium (Campine area) as the host rock for high-level and/or long-lived radioactive waste disposal. Since then several studies on characterization and modelling of groundwater flow for the aquifers above and below the Boom Clay have been carried out for better understanding of water and solutes transport in this area as this is important for demonstrating feasibility and safety of such a radioactive waste disposal. According to Vandersteen et al. (2012), the detailed hydrogeological characterization of the aquifers below the Boom Clay especially Oligocene and Ledo-Paniselian-Brusselian aquifers is of high importance for reducing the uncertainty of the current groundwater flow model for the aquifers below the Boom Clay. However the amount of available hydraulic conductivity data for these aquifers is limited and has not yet been used for the model parameterization. To continue with characterization and modelling of groundwater flow for the aquifers below the Boom Clay this study used data from a portable air permeameter to estimate saturated hydraulic conductivities for the Oligocene and Bartoon aquifer system (Potums, 2014). The up-scaled saturated hydraulic conductivity estimates together with pumping test data from the Oligocene and Ledo-Paniselian-Brusselian aquifers are integrated into the current groundwater flow model for the aquifers below the Boom Clay. Small-scale air permeameter-based measurements are important as they incorporate real-world aquifer heterogeneity into the model hence improve the conceptual model, and potentially model performance. Results show that on average the Ledo-Paniselian-Brusselian (LPB) aquifer is approximately 30 times more permeable than the Oligocene aquifer. The average horizontal hydraulic conductivity value for this aquifer is 13.10 m/d. Because of its higher conductivity, people will preferably pump from the LPB aquifer and not from the Oligocene aquifer. Also, because of the low transmissivity of the Oligocene aquifer, pumping effects in this aquifer are likely to remain local, while for the LPB aquifer (which has a higher transmissivity), there are regional effects of pumping. Moreover, mathematical equations describing the depth-dependency for hydraulic conductivities for the Zelzate formation in the Oligocene aquifer have been established. The integration of the air permeameter-based data and pumping test data from the Oligocene and LPB aquifers into the current groundwater flow model for the aquifers below the Boom Clay makes the model parameterization more data-based on realistic. iii Table of contents Acknowledgement ........................................................................................................................... i Abstract ........................................................................................................................................... ii Table of contents ............................................................................................................................ iii List of figures ................................................................................................................................. iv List of tables ................................................................................................................................... vi List of symbols and SI units.......................................................................................................... vii Abbreviations ............................................................................................................................... viii 1 Introduction ............................................................................................................................. 1 1.1 Background and general context ...................................................................................... 1 1.2 Problem Statement ........................................................................................................... 2 1.3 Objectives and Scope ....................................................................................................... 3 1.3.1 General objective ...................................................................................................... 3 1.3.2 Specific objectives .................................................................................................... 3 2 Literature review ..................................................................................................................... 3 2.1 Air permeametry .............................................................................................................. 3 2.2 Hydrostratigraphy of the study area ................................................................................. 5 2.3 Current groundwater model for the deep aquifers in North-East Belgium .................... 10 3 Methodology ......................................................................................................................... 19 3.1 Characterization of borehole cores from the aquifers below the Boom Clay using the air permeameter .............................................................................................................................. 19 3.2 Evaluation of available pumping test data from deep aquifers and comparison to the air permeameter measurements ...................................................................................................... 21 3.3 Up-scaling of the air permeameter-based hydraulic conductivity estimates .................. 21 3.4 Integration of air permeameter and pumping test data in the current DAP model ........ 23 3.5 Sensitivity analysis and calibration of the updated DAP model .................................... 32 4 Results and discussion .......................................................................................................... 33 iv 4.1 Air permeameter-based measurements .......................................................................... 33 4.2 Pumping test data ........................................................................................................... 36 4.3 Comparison of air permeameter measurements versus pumping test data .................... 36 4.4 Up-scaled air permeameter-based hydraulic conductivity ............................................. 37 4.5 Interpolated maps of hydraulic conductivity .................................................................. 40 4.6 Updated DAP model ...................................................................................................... 44 5 Conclusions and Recommendations ..................................................................................... 53 6 References ............................................................................................................................. 54 7 Appendices ............................................................................................................................ 58 7.1 Appendix 1 ..................................................................................................................... 58 7.2 Appendix 2 ..................................................................................................................... 68 List of figures Figure 1. A geological cross section showing the major geological formations in the Campine area (from Vandersteen et al., 2013). ............................................................................................. 1 Figure 2. A picture of the TinyPerm II Portable Permeameter (Source: www.azom.com). .......... 4 Figure 3. Extent of the DAP model (in black) in relation to the presence of Boom Clay, Asse/Ursel Clay and the fault system of the Roer Valley Graben (from Vandersteen et al., 2012). A map of Belgium with the location of the Boom Formation is shown in the upper right corner (from Vandersteen et al., 2014). ..................................................................................................... 6 Figure 4. Vertical cross-section of the conceptual DAP model (Gedeon & Wemaere, 2009; Vandersteen et al., 2012, 2013). ................................................................................................... 10 Figure 5. Horizontal schematization of the DAP model (example