Technical Report 88-01

487 Pages·1991·20.02 MB·English

by  A. Gautschi, W. Balderer, B.E. Lehmann, A. Matter, Tj. Peters, H. Schmassmann and F.J. Pearson (Eds.)

APPLIED ISOTOPE HYDROGEOLOGY
A CASE STUDY IN NORTHERN SWITZERLAND
Nagra Cedra Cisra
Nationale Societe cooperative Societd cooperativa
Genossenschafi nationale. nazmnale
fur die Lagerung pour I'entreposage per I'imrnagazzinarnento
radioaktiver Abfalle de dechets radioactifs di scorie radioattive
TECH NI C AL
REPORT 88-01
APPLIED ISOTOPE HYDROGEOLOGY-
A CASE STUDY IN
NORTHERN SWITZERLAND
F.J. Pearson Jr., W. Balderer, H.H. Loosli, 5.E. Lehmann,
A. Matter, Tj. Peters, H. Schmassmann, A. Gautschi
With contributions by J.N. Andrews, P. Baertschi, G. Dappen, J.-Ch. Fontes,
M. Ivanovich, M. Kullin, J.-L. Michelot, K. Ramseyer, D. Rauber, W. Rauert,
S. Soreau, W. Stichler
MAY 1991
Parkstrasse 23 5401 Baden/Switzerland Tel. [phone]
Studies in Environmental Science 43
APPLIED ISOTOPE HYDROGEOLOGY
A CASE STUDY IN NORTHERN SWITZERLAND
F.J. Pearson Jr.7, W. Balderer2, H.H. Loosli3,
B.E. Lehmann3, A. MatteP, Tj. Peters5,
H. Schmassmann" and A. Gautschi'
With contributions by
J.N.
ELSEVIER SCIENCE PUBLISHERS B.V.
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Studies in Environmental Science
Other volumes in this series
1 Atmospheric Pollution 1978 edited by M.M. Benarie
2 Air Pollution Reference Measurem.ent Methods and Systems
edited by T. Schneider, H.W. de Koning and L.J. Brasser
3 Biogeochemical Cycling of Mineral-Forming Elements
edited by P.A. Trudinger and D.J. Swaine
4 Potential Industrial Carcinogens and Mutagens by L. Fishbein
5 Industrial Waste Management by S.E.J plrgensen
6 Trade and Environment: A Theoretical Enquiry by H. Siebert, J. Eichberger, R. Gronych
and R. Pethig
7 Field Worker Exposure during Pesticide Application edited by W.F. Tordoir and
E.A.H. van Heemstra-Lequin
8 Atmospheric Pollution 1980 edited by M.M. Benarie
9 Energetics and Technology of Biological Elimination of Wastes
edited by G. Milazzo
10 Bioengineering, Thermal Physiology and Comfort edited by K. Cena
and J.A. Clark
11 Atmospheric Chemistry. Fundamental Aspects by E. MBszhros
12 Water Supply and Health edited by H. van Lelyveld and B.C.J. Zoeternan
13 Man under Vibration. Suffering and Protection edited by G. Bianchi, K.V. Frolov and
A. Oledzki
14 Principles of Environmental Science and Technology by S.E. Jplrgensen
and I. Johnsen
15 Disposal of Radioactive Wastes by Z. Olouhrj
16 Mankind and Energy edited by A. Blanc-Lapierre
17 Quality of Groundwater edited by W. van Duijvenbooden, P. Glasbergen
and H. van Lelyveld
18 Education and Safe Handling in Pesticide Application edited by E. A.H. van Heemstra-
Lequin and W.F. Tordoir
19 Physicochemical Methods for Water and Wastewater Treatment edited by
L. Pawlowski
20 Atmospheric Pollution 1982 edited by M.M. Benarie
21 Air Pollution by Nitrogen Oxides edited by T. Schneider and L. Grant
22 Environmental Radioanalysis by H.A. Das, A. Faanhof and H.A. van der Sloot
23 Chemistry for Protection of the Environment edited by L. Pawlowski, A.J. Verdier and
W.J. Lacy
24 Determination and Assessment of Pesticide Exposure edited by M. Siewierski
25 The Biosphere: Problems and Solutions edited by T.N. VeziroQlu
26 Chemical Events in the Atmosphere and their Impact on the Environment edited by
G.B. Marini-Bettolo
27 Fluoride Research 1985 edited by H. Tsunoda and Ming-Ho Yu
28 Algal Biofouling edited by L.V. Evans and K.D. Hoagland
29 Chemistry for Protection of the Environment 1985 edited by L. Pawlowski, G. Alaens
and W.J. Lacy
30 Acidification and its Policy Implications edited by T. Schneider
31 Teratogens: Chemicals which Cause Birth Defects edited by V. Kolb Meyers
32 Pesticide Chemistry by G. Matolcsy, M. NBdasy and V. Andriska
33 Principles of Environmental Science and Technology (second revised edition)
by S.E.J plrgensen and I. Johnson
34 Chemistry for Protection of the Environment 1987 edited by L. Pawlowski, E. Mentasti,
C. Sarzanini and W.J. Lacy
35 Atmospheric Ozone Research and its Policy Implications edited by T. Schneider,
S.D. Lee, G.J.R. Wolters and L.D. Grant
36 Valuation Methods and Policy Making in Environmental Economics edited by H. Folmer
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37 Asbestos in the Natural Environment by H. Schreier
38 How to Conquer Air Pollution. A Japanese Experience edited by H. Nishimura
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41 Evaluation of Environmental Data for Regulatory and Impact Assessment by S.
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VII
PREFACE
In 1980, Nagra, the Swiss National Cooperative for the Storage of Radioactive Waste,
began a comprehensive field investigation programme to assess the feasibility and safety
of a repository for the final disposal of high-level radioactive waste in northern Switzer-
land. The host rock of first priority was crystalline basement covered by a few hundred
metres of sedimentary rocks. The various investigations cover an area of about 1200 km2
and include a regional geophysical programme, a regional hydrogeological programme
comprising hydrodynamic modelling and hydrogeochemical investigations, a neotectonic
programme and a deep drilling programme. Seven deep boreholes with depths between
1306 and 2482 m have been drilled to date. As the study programme for the seventh
borehole was still in progress during the final preparation of this report, only incomplete
results were available for inclusion in this report. The scientific programmes were
designed by Nagra and its geology consultants and carried out under the project
management of Nagra by more than 200 scientists from over 50 companies and univer-
sities from 8 countries.
An understanding of the deep groundwater flow regime is needed to predict flow paths,
travel times and dilution effects of groundwater moving from a repository location to the
biosphere. To assess the flow field, regional and local hydrodynamic models have been
prepared. Currently, extensive improvements to the input data are being made and aniso-
tropic flow properties are being included for several formations. Subsequently, validation
of the hydrodynamic models with the results of the hydrogeochemical investigations will
be attempted. The isotopic investigations presented in this report will probably be the
most important contribution to this validation.
The hydrogeochemical programme started in 1981 with the collection of waters from
about 140 springs and wells of different aquifers in northern Switzerland and adjacent
areas; this was called the "regional programme" (SCHMASSMA" AND OTHERS,
1984). Detailed hydrochemical and isotopic analyses have been carried out on these
samples. About 60 waters from the Nagra deep boreholes were also sampled and
analysed, of which some 40 gave useful results. Additional geochemical and isotopic data
on rock material are also available from these boreholes. A literature study yielded com-
plementary hydrochemical data, the so-called "Fremde Analysen", both from points
sampled during the regional programme and from additional points.
The purpose of this report is to present all the isotope data collected within the Nagra
programme in northern Switzerland. The report also includes the first comprehensive
synthesis and interpretation of these data. It is anticipated that special aspects of the data
interpretation will be discussed elsewhere in the reviewed scientific literature.
Marc T h y
Depanment Head, Geology
Nagra, Badeq Switzerland
This Page Intentionally Left Blank
IX
CONTENTS
PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv
ILLUSTRATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Xviii
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Overview of This Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Scope of Data Presented . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Reporting of Isotopic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5 Regional Geology and Stratigraphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5.2 Crystalline Basement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5.3 Sedimentary Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.6 Hydrogeology and Hydrochemistry .............................. 15
1.6.1 General Situation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.6.2 Data Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.6.3 Groundwaters in Tertiary and Upper Malm Aquifers . . . . . . . . . . . . . 17
1.6.4 Groundwaters in the Dogger. Lias and Keuper Aquifers . . . . . . . . . . 20
1.6.5 Groundwaters in the Upper Muschelkalk Aquifer . . . . . . . . . . . . . . . 22
1.6.6 Groundwaters of Lower Triassic and Permian Aquifers . . . . . . . . . . . 24
1.6.7 Groundwaters in the Crystalline Basement .................... 26
2. LIMITATIONS OF SAMPLING AND ANALYTICAL PROCEDURES . 31
2.1 contamination of Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.1.1 Large-Volume Gas Samples for 39Ara nd "Kr . . . . . . . . . . . . . . . . . . 33
2.1.2 Samples for Carbon Isotopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.1.2.1 Samples from Test Borehole Programme ..................... 37
2.1.2.2 Other Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.2 Comparison of Carbon Isotope Results From Conventional and Ah4S
Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.3 Evaluation of Replicate Analytical Data .......................... 44
2.3.1 Dissolved Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.3.1.1 Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.3.1.2 Noble Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.3.2 Uranium, Thorium and Daughter Elements .................... 48
3 . INFILTRATION CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3.1 Isotopic Composition of Modern Recharge ........................ 65
3.1.1 Stable Isotope-Altitude Relationships ........................ 68
3.1.2 6 "0-6 *H Relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.1.3 Local Altitude-Temperature Equations ....................... 80
3.1.4 Stable Isotope-Temperature Relationships ..................... 82
3.2 Isotopic Composition of Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
3.2.1 Samples from Quaternary. Tertiary and Malm Aquifers . . . . . . . . . . . 90