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Title: Effects of temporary and permanent blankets on tides and currents in East River : hydraulic model investigation
Authors: United States. Army. Corps of Engineers. New York District.
Bobb, William H.
Hill, Thomas C.
Keywords: Blankets
Protective covering
Underground tunnel
Tunnel construction
East River
New York Harbor
Hydraulic models
River currents
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; H-69-7.
Description: Miscellaneous Paper
Abstract: The New York Transit Authority is considering constructing a new tunnel under East River between 63d Street, Manhattan, and 41st Avenue, Long Island City, New York, by either the open trench or the compressed air shield method. For the compressed air shield method, a temporary protection blanket would be required to prevent possible blowout during construction, and after construction is completed, a permanent blanket will be required to provide protection for the tunnel. The existing comprehensive fixed-bed model of New York Harbor was used to determine the effects of both permanent and temporary blankets in the west channel of the East River on existing hydraulic conditions. Model tests were conducted to determine the effects of (A.) a permanent blanket with a top elevation of -45 ft mlw, (B.) a temporary blanket with a top elevation of -35 ft mlw, and (C.) the temporary blanket at elevation -35 ft mlw plus a movable section 90 feet wide at the top, constructed to an elevation of -5 ft mlw, on tides and currents in adjacent reaches of East River. The following general conclusions appear valid on the basis of the model test results reported herein. The blanket tested would have no major effect on tide heights. The permanent blanket with a top elevation of - 45 ft mlw caused no noticeable change at any of the tide stations at which measurements were obtained. The temporary blankets caused slight increases in the plane of low water upstream of the proposed fills. Current strengths in general were slightly increased in the channel east of Welfare Island and decreased in the channel west of Welfare Island as a result of installing the permanent blanket. For all plans tested, current velocities in the immediate vicinity of the proposed fills would be increased appreciably but would still be of the same order of magnitude as existing currents in Hell Gate, the reach with maximum currents for existing conditions. Because of the magnitude of the local currents, placement and maintenance of the movable temporary blanket may be difficult. With both temporary blankets installed, navigation in the west channel could be adversely affected, because of both the magnitude of the currents and the restriction in width of the channel.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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