bill wilborn ugta federal sub-project director 2011 community environmental monitoring program...
TRANSCRIPT
Bill WilbornUGTA Federal Sub-Project Director
2011 Community Environmental Monitoring Program (CEMP) Workshop
July 26, 2011
Underground Test Area (UGTA) Overview
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Presentation Topics
• UGTA Strategy Overview
• Corrective Action Unit (CAU) Status/Changes
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UGTA Closure Strategy
• Corrective Action Investigation (Phase I and II)
– Corrective Action Investigation Plan (CAIP)
– Data collection
– Modeling
– Contaminant boundary
– Peer review
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• Corrective Action Decision/Corrective Action Plan
– Corrective Action Decision Document/ Corrective Action Plan (CADD/CAP)
– Use restriction boundary
– Regulatory boundary
– Model evaluation
UGTA Closure Strategy (continued)
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• Closure
– Closure Report (CR)
– Address boundary changes from model evaluation
– Closure in place with long-term monitoring
– Institutional controls
UGTA Closure Strategy (continued)
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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
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Frenchman Flat Well Sites
•ER-5-5
•ER-11-2
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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
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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
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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
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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
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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
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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
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Radiation Facts