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Overview of UGTA Federal Sub-Project and Community Environmental Monitoring Workshop 2011

This document encapsulates the presentation by Bill Wilborn, Director of the UGTA Federal Sub-Project, during the Community Environmental Monitoring Program (CEMP) workshop on July 26, 2011. Key topics discussed include the strategy overview for UGTA, updates on corrective action units and investigations, data collection methods, modeling of contaminants, peer review findings, closure strategies, and the implementation of long-term monitoring and institutional controls. Highlights include the identification of critical well sites and the assessment of radionuclide transport in relation to groundwater aquifers.

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Overview of UGTA Federal Sub-Project and Community Environmental Monitoring Workshop 2011

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  1. Underground Test Area (UGTA) Overview Bill Wilborn UGTA Federal Sub-Project Director 2011 Community Environmental Monitoring Program (CEMP) Workshop July 26, 2011

  2. Presentation Topics • UGTA Strategy Overview • Corrective Action Unit (CAU) Status/Changes

  3. UGTA Closure Strategy • Corrective Action Investigation (Phase I and II) • Corrective Action Investigation Plan (CAIP) • Data collection • Modeling • Contaminant boundary • Peer review

  4. UGTA Closure Strategy (continued) • Corrective Action Decision/Corrective Action Plan • Corrective Action Decision Document/ Corrective Action Plan (CADD/CAP) • Use restriction boundary • Regulatory boundary • Model evaluation

  5. UGTA Closure Strategy (continued) • Closure • Closure Report (CR) • Address boundary changes from model evaluation • Closure in place with long-term monitoring • Institutional controls

  6. Frenchman Flat • FY 2010 completed Peer Review/Model accepted by State of Nevada Division of Environmental Protection (NDEP) • Currently completing CADD/CAP – the first one for UGTA • Building first two roads and pads for model evaluation wells • American Recovery and Reinvestment Act funded • Sites identified as ER-5-5 and ER-11-2

  7. Frenchman Flat Well Sites • ER-5-5 • ER-11-2

  8. Yucca Flat • Initiating scoping of supplemental analysis for flow and transport modeling (outcome from Preemptive Review) • Models captured reasonable range of outcomes maximizing extent of contamination • Low probability any water with radionuclide concentrations exceeding maximum contaminant level will leave Yucca Flat • Most radionuclide inventory is retained within the vadose zone or saturated volcanics • Extent of lower carbonate aquifer (LCA) exceedence volume (EV) is controlled by non-sorbing radionuclides from a small fraction of the tests

  9. Yucca Flat(continued) • Tests with working points in the unsaturated zone contribute little to the LCA EV or to maximum southern extent of contamination in the LCA • Key sensitivities with faults creating fast path from the volcanics to the LCA – major faults control the extent of migration Conclusion: Extend Phase I to focus on major uncertainties and address during CADD/CAP model evaluation

  10. Rainier Mesa/Shoshone Mountain • Continuing flow and transport model analysis and evaluation • Concluded pre-emptive review held end of March for opening discussion with NDEP on path forward • Similar strategy considerations for Yucca Flat need to be made for Rainier Mesa/Shoshone Mountain in regard to where focus on uncertainties should be

  11. Rainier Mesa/Shoshone Mountain(continued) • Tests Clearwater and Wineskin seem to dominate radionuclide transport to saturated zone; these two tests make up 25% of the Rainier Mesa/Shoshone Mountain inventory • Path forward may be similar to Yucca Flat in that an extended Phase I may need to be implemented then move to CADD/CAP and model evaluation

  12. Pahute Mesa • Will complete well development, testing, and sampling for three wells: • ER-20-4 (one completion zone) • ER-20-8 (two completion zones) • ER-EC-12 (two completion zones) • Phase II drilling campaign and geology • ER-20-7 • ER-20-8 • ER-20-8 #2 • ER-EC-11 • ER-EC-12 • ER-20-4 • ER-EC-13 • ER-EC-15

  13. What Have We Learned to Date? • Newly acquired data supports the conceptual model • Contamination moves off Pahute Mesa in deeper units to stratigraphically higher units as caldera structure down drops the volcanics to the south • The Benham Aquifer is hypothesized to be the main aquifer of concern at the leading edge of the contaminant plume • Additional well installation and hydraulic testing are designed to increase confidence in our modeling strategy

  14. Radiation Facts

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