ANT11 Presentation, October, 10-13, 2011 David Vardiman Project Engineer Geotechnical Design and Excavation 1 Sanford Lab at Homestake, Lead, SD 4850L Geotechnical Investigations ANT11 Conference, Philadelphia, PA Oct. 10 – 13th, 2011

ANT11 Presentation, October, 10-13, 2011 Overview – Chapter 5.3 PDR Please reference the DUSEL Project Preliminary Design Report 2

ANT11 Presentation, October, 10-13, 2011 DUSEL Project Basis of Design 3 Design and Construct a Safe, Stable, Functional Underground Scientific Laboratory Mid-Level Campus

ANT11 Presentation, October, 10-13, 2011 DUSEL Project PDR L & 7400L 4

ANT11 Presentation, October, 10-13, 2011 DUSEL Project PDR 4850L & 7400L Dimensions 5

ANT11 Presentation, October, 10-13, 2011 LBNE CD – 1 33kT LAr 800 Level 6

ANT11 Presentation, October, 10-13, 2011 LBNE CD – 1 33kT LAr 4850 Level 7

ANT11 Presentation, October, 10-13, 2011 LBNE CD – 1 200kT WCD 8

ANT11 Presentation, October, 10-13, 2011 General Site Stratigraphy 9

ANT11 Presentation, October, 10-13, 2011 DUSEL 4850L Site Investigation Geotechnical Assessment Criteria Rock Quality Thresholds (for GOOD Rock) – RMR > 60 –Q > 10 –No unmitigatable adverse features –Predictable rock properties –Predictable state of stress in the rock mass Issues – Hydrology – Adequate database for preliminary design – Identify critical characteristics 10

ANT11 Presentation, October, 10-13, 2011 DUSEL 4850L Geotechnical Site Investigation Major Tasks 11 Drift Mapping ft (1311 meters) Drilling and Core Logging ft (1646 meters) Televiewer Logging ~5000 ft (1524 meters) In-Situ Stress Measurements - 8 tests Laboratory Tests - 72 samples Post PDR Design Developments Ground Water Monitoring Calibration To Recent Davis Campus Excavation Davis Campus Laser Scanning – Joint Persistence

ANT11 Presentation, October, 10-13, 2011 Drift Mapping 11 domains identified with drift mapping 1,500 geological and geotechnical data points Contacts & transition zones between major Poorman and Yates mapped along drifts Rhyolite units mapped 12

ANT11 Presentation, October, 10-13, 2011 Drilling & Core Logging 13 Oriented Core Boxed Core

ANT11 Presentation, October, 10-13, 2011 Borehole Televiewer 14

ANT11 Presentation, October, 10-13, 2011 In-Situ Stress Measurements 15 Golder 4850 Level Data Normal Stress (psi) Depth (ft) Historical Homestake Stress Measurement Data and Golder 4850 Level Averages (W. Pariseau) GAC Chairman

ANT11 Presentation, October, 10-13, 2011 Laboratory Testing 16

ANT11 Presentation, October, 10-13, 2011 Groundwater Monitoring 17 Initial inflow <1 L/min Declined over time Geochemical sampling 950 psi Ongoing Pressure Monitoring

ANT11 Presentation, October, 10-13, L Rock Mass Characterization 18 Lithology, Contacts & Folding Joints, Foliation, & Contacts Laboratory Testing Geological Zonation In Situ Stress Integrated Characterization

ANT11 Presentation, October, 10-13, 2011 Data Interpretation 19

ANT11 Presentation, October, 10-13, 2011 Lithology and Structure 20 Rhyolite Zone

ANT11 Presentation, October, 10-13, 2011 Geological Zonation 21 Geological zones based on: Lithology Structure Joints & Foliation

ANT11 Presentation, October, 10-13, 2011 In Situ Stress Tensor 22 Principal Stress Magnitude (MPa) Dip (°) Trend (°) s1s s2s s3s Principal Stress Sub-Vertical Horizontal Stresses Nearly Equal Magnitude Potential for Spalling in Brittle Rock Rock Bursts Will Not Develop 7400L ~ Stresses are estimated to be 45% Higher

ANT11 Presentation, October, 10-13, L Geotechnical Conclusions 23 The field and laboratory data, and the geotechnical analyses revealed that: Overall, the rock is of good quality (RMR>60 and Q>10) No adverse geological or structural features were found that could not be mitigated Rock mass properties vary but are predictable In situ state of stress is favorable Rock bursts will not develop Evaluation is consistent with the 40+ years of operating performance in the Davis Chamber and recent excavation experience in the enlargement of the new Davis Campus LCAB & IAB review recommendations

ANT11 Presentation, October, 10-13, 2011 LCAB Conclusions 24 The field and laboratory data, and the geotechnical analyses revealed that: A combination of favorable rock mass strength and structural conditions and an in situ stress field that is reasonably benign means that a stable 66 m diameter 102 m high vertical cylindrical cavern can be constructed at the selected location on the 4850 level of the Homestake mine. While the combination of cavern size and depth below surface of the 200 Kt WCD is beyond precedent, the factors that control the stability of the cavern are well within our experience and technical knowledge base. It has been demonstrated that structurally controlled gravity-driven wedge instability can be controlled by a carefully designed excavation sequence and the installation of grouted rockbolts and cables as was done in the Gjøvik, Norway Ice Hockey cavern. In fact, the Gjøvik cavern has approximately the same width as the 200Kt WCD, but its letterbox configuration is a more severe geometry that can produce larger wedges than the axisymmetric configuration of the WCD. It has also been demonstrated that adverse in-situ stress conditions giving rise to spalling and even rockbursting can also be controlled by carefully designed excavation and support installation methods such as those used for the Sudbury Neutrino Observatory cavern. Even though the WCD is located at significant depth, the rock strength is sufficient so that stress induced spalling will be limited and rock bursting will not develop, as demonstrated by both analyses and the extensive experience in mining and driving drifts at the 4850 level.

ANT11 Presentation, October, 10-13, L Key Future Tasks Further Geotechnical Site Investigation activities should be completed prior to start of next stage of design Laser scanning of required levels Geological/Geotechnical mapping of required levels Geotechnical core holes for proposed boreholes and shafts; surface to 4850L, 3650L to 4850L and 4850L to 7400L borehole Detailed investigation of planned excavations (core drilling) Detailed investigation of LC-1 (excavation and core drilling) 25

ANT11 Presentation, October, 10-13, 2011 Questions and Discussion 26