Geology and Hydrofacture, Moose River Power Tunnel, New Yorkby Arthur H. Stukey, Harza Engineering Co, United States,
Vincent J. Zipparro, Harza Engineering Co, United States,
Abstract: The Moose River Hydroelectric Project, Lyonsdale, New York, is constructed in Precambrian gneiss of the western Adirondack Mountains. A key element of the project was construction and operation of a 4550-ft long unlined, 15-ft diameter pressure tunnel. During the first tunnel filling, monitoring personnel at ground level noted three distinct thuds or bumping noises coming from the tunnel. Immediately following filling and during the next several days, tunnel leakage emerged at several locations. The power tunnel was dewatered for inspection and found to be structurally sound. Several previously tight, sub-horizontal fractures had opened 0.25 to 0.5 in. at the tunnel wall surface. Some newly developed fractures showed 0.25 in. of displacement toward the center of the tunnel. The tunnel was refilled under close observation which included acoustic monitoring in boreholes adjacent to the tunnel, and recording background microseismic levels several hundred ft away from the tunnel. The geophysical monitoring indicated no further strain or fracturing. After twelve months of operation, tunnel leakage diminished from 9 cfs to 4 cfs. Saturated leaves and pine needles were introduced into the tunnel flow during normal operations to reduce seepage.
Subject Headings: Tunnels | Hydro power | Rivers and streams | Geology | Cracking | Leakage | Seepage | Construction management | Mountains | North America | United States | New York
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