Ground Water at Yucca Mountain How High Can It Rise? -- Copyright -- Contents -- Executive Summary -- INTRODUCTION -- HAS IT HAPPENED? -- Soils -- Springs -- Textural/Morphologic Evidence -- Breccias -- Isotopes -- CONCLUSION -- CAN IT HAPPEN? -- Increased Rainfall -- Volcanic Intrusion -- Earthquakes -- RECOMMENDATIONS -- Steep Hydraulic Gradient -- Paleozoic Carbonate Aquifer -- Scientific Integration/Coordination -- 1-Introduction -- REFERENCES -- 2-Water Levels in the Vicinity of the Proposed Repository in the Last 100,000 Years -- GEOLOGIC SETTING OF YUCCA MOUNTAIN AND ENVIRONS -- Paleozoic -- Mesozoic -- Cenozoic -- Extension -- Volcanic Activity -- Active Tectonics -- EPISODIC GROUND-WATER DISCHARGE THESIS -- SOIL DEVELOPMENT AND GEOMORPHOLOGICAL CHARACTER OF THE REGION -- HYDROLOGIC EVIDENCE FROM SPRINGS -- Devils Hole -- Wahmonie Spring -- The Age of the Wahmonie Site -- Cane Spring -- MORPHOLOGIC/TEXTURAL EVIDENCE EXHIBITED BY CHEMICAL PRECIPITATES -- EVIDENCE EXHIBITED BY BRECCIAS -- GEOCHEMICAL AND MINERALOGICAL CONSIDERATIONS -- ISOTOPIC EVIDENCE -- Stable Isotopes: 13C and 18O -- Tracer Isotopes: Sr, U, and Th -- CONCLUSIONS -- RECOMMENDATIONS -- Additional Characterization of Carbonate Veins in Core -- Fluid Inclusion Studies -- Isotopic Composition of Windblown Dust -- Additional Studies at Site 199 -- REFERENCES -- 3-Might Increased Rainfall Cause Flooding of the Proposed Repository? -- INTRODUCTION -- HYDROGEOLOGICAL SETTING -- A MODEL OF GROUND-WATER FLOW AT YUCCA MOUNTAIN -- EVIDENCE FOR PAST VARIABILITY IN RAINFALL -- Chronological Framework -- Geographic and Paleohydrologic Framework -- The Paleoecological Record -- PALEOCLIMATIC RECONSTRUCTIONS -- Full-Glacial Climates -- The Terminal Wisconsin-Early Holocene -- Climates of the Last 8,000 Years.

MODEL CALCULATIONS OF POTENTIAL RISE IN THE GROUND-WATER TABLE DUE TO INCREASED PRECIPITATION -- CONCLUSIONS -- RECOMMENDATIONS -- REFERENCES -- 4-Can an Igneous Intrusion Raise the Water Table to the Proposed Repository Level? -- SUMMARY OF TERTIARY VOLCANIC HISTORY OF THE REGION -- STYLE AND SIZE OF A LIKELY INTRUSION IN THE YUCCA MOUNTAIN REGION -- MODELS OF WATER TABLE RISE ACCOMPANYING DIKE INTRUSION -- POSSIBLE DEEP (LOWER CRUSTAL) MAGMA CHAMBERS IN THE YUCCA MOUNTAIN REGION -- PROBABILISTIC ASSESSMENT OF THE LIKELIHOOD OF A BASALTIC DIKE INTRUSION -- CONCLUSIONS -- RECOMMENDATIONS -- REFERENCES -- 5-Could a Nearby Earthquake Cause Flooding of the Proposed Repository? -- INTRODUCTION -- Contemporary Crustal Motions -- Recommendation -- HYDROLOGIC RESPONSES TO EARTHQUAKES -- HISTORICAL EVIDENCE -- Loma Prieta, California -- Anchorage, Alaska -- Borah Peak, Idaho -- RECOMMENDATION -- EARTHQUAKE MODELS -- Introduction -- Dislocation Models -- Regional Stress Change Models -- Sources of Information on In Situ Physical Properties -- CONCLUSIONS BASED ON RESULTS OF MODELING TO DATE -- A Possible Alternate Modeling Approach: Discontinuum Analysis of Ground-Water Motion -- RECOMMENDATION -- EARTHQUAKE PROBABILITY -- CONCLUSIONS -- RECOMMENDATIONS -- REFERENCES -- 6-Summary of Conclusions and Recommendations -- HAS IT HAPPENED? -- Field Evidence -- Soils -- Modern and Paleo-Springs -- Textural/Morphologic Evidence -- Breccias -- Isotopes -- Paleobiological Evidence -- Recommendations -- CAN IT HAPPEN? -- Water Table Response to an Increase in Rainfall -- Recommendation -- Water Table Response to a Volcanic Intrusion -- Recommendations -- Water Table Response to Earthquakes -- Evidence from Historic Earthquakes -- Earthquake Models -- Recommendation -- ADDITIONAL ISSUES OF CONCERN -- Steep Hydrologic Gradient.

Essential Data for Modeling the Ground-Water Flow System -- Recommendation -- Scientific Integration/Coordination -- Recommendation -- Flexibility in the Scientific Program -- Appendixes -- Appendix A A Review of the Isotope Geochemistry of the Yucca Mountain, Nevada, Proposed Nuclear Waste Repository Site. -- Summary -- Introduction -- Ancient Ground Waters vs. Modern Ground Waters -- C-O-H Isotopes -- O and H: -- C and O: -- U and TH Isotopes -- SR Isotopes -- New Data on Calcite from Drill Holes -- Conclusions -- Recommendations -- Acknowledgements -- References -- Useful References Not Cited in the Text -- Appendix B Yucca Mountain: Ground-Water Flow -- Introduction -- Hydrologic Data Set -- Permeability Structure -- Aquifer Pressures (Hydraulic Potential) -- Discharge and Recharge Areas -- Modeling Studies -- Recommendations -- Specific Recommendations -- References -- Appendix C The Effects of Pluvial Climates In The Vicinity of Yucca Mountain: A Summary -- Introduction -- Chronological Framework -- Geographic and Paleohydrologic Framework -- The Paleoecological Record -- Selected Fossil Records -- Evidence of Phreatic Environments -- Paleoclimatic Reconstructions -- Full-Glacial Climates -- The Terminal Wisconsin-Early Holocene -- Climates of the Last 8000 Years -- Conclusions and Information Needs -- References -- Appendix C Supplement -- Indicator Plant Species in Paleoclimate Studies -- I. Warm desert plant species: -- II. Cold desert or steppe plant species: -- III. Woodland plant species: -- IV. Forest plant species: -- V. Wet-ground plant species: -- Appendix D Response of the Ground-Water System at Yucca Mountain to an Earthquake -- Abstract -- Introduction -- Earth Tides and Atmospheric Loads -- Elastic and Hydrologic Parameters -- Fault Dislocation -- Conclusion -- Acknowledgment -- References.

Appendix E Probabilities of Earthquakes Near Yucca Mountain, Nevada -- Purpose -- Faults and Parameters -- Analysis -- Results -- Summary -- References.