Earth science collaborations for Deep Underground Science and Engineering Laboratory

Work on the Deep Underground Science and Engineering Laboratory (DUSEL) has made great progress in 2006, with the release of a Deep Science report by a site-independent study (Solicitation-1, or S-1) and the submittals of two S-2 conceptual design reports - one from the active Henderson mine in Colorado and the other from the abandoned (now State-owned) Homestake mine in South Dakota - towards the final DUSEL site selection scheduled for 2007. The earth-science collaborations in hydrology, geochemistry, geophysics, rock mechanics, ecology/geomicrobiology, and coupled processes have evolved since 2000 to include recent community-wide deliberations in six S-1 working groups, and extensive interest expressed through over 60 Letters of Interest to the Homestake Authority and Collaboration. The proposed initial suite of experiments at Homestake can start with establishing a seismic network by using boreholes and along multiple levels, sampling fluid for in situ hydrogeochemical/biological states, and improving site models using information about localized distributions of low-rate and slightly basic inflows into underground workings. The siting of niches and blocks for long-term coupled process testing and the design of large caverns can proceed with DUSEL entries. There is also interest in designing energy-related studies, for example, using a ventilation shaft or dead-end drift for carbon dioxide injection experiments. As another example, earth-science investigators are collaborating with physicists on geoneutrino and other radiation studies to quantify the distributions of geothermal sources in the earth's crust and at its core. Given the expected high stress at great depths, large excavations for physics detectors, and elevated temperatures anticipated in deep boreholes, the Homestake offers ample opportunities for DUSEL collaborations to design field-testing programs for solving critical earth-science problems.