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Published: 1997

Total Pages: 0

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Lock and Dam 25 is located on the Mississippi River, 241.5 miles upstream of its confluence with the Ohio River, The principal existing structures are the main 110- by 600-ft lock located along the right descending bank, an incomplete auxiliary lock located riverward of the main lock, and a 1,296-ft dam with fourteen 60-ft tainter gates and three 100-ft roller gates. An overflow dike with top elevation of 434.0 (elevations (el) are in feet referred to the National Geodetic Vertical Datum) extends from the dam to high ground on the left bank. The dam provides a navigation pool that extends upstream about 32 miles to Lock and Dam 24. The dam is operated to maintain a navigation pool that varies from el 434.0 to 429.7 at the dam and from el 434.0 to 437.0 at Mosier Landing (river mile 260.3). As the riverflow increases, the gates are raised to prevent exceeding the limits at Mosier Landing. A fixed-bed model reproduced about 3.7 miles of the Mississippi River and adjacent overbank from about 9,800 ft upstream to about 9,600 ft downstream of the existing dam to an undistorted scale of 1:120. Four locations are being considered for a new lock at Dam 25. The model investigation was concerned with evaluating navigation conditions for each lock location and identifying any needed modifications to the navigation channel alignment, guard wall lengths, or remedial structures. This information will also be used in the preliminary design of locks at other dam sites along the upper Mississippi River. Results of the investigation revealed that with all locations, realigning the navigation channel upstream of the lock and adding a ported upstream guard wall would reduce the outdraft, eliminate the need for a helper towboat, and improve navigation conditions for tows entering and leaving the upper lock approach.

Download or read book Navigation Conditions at Lock and Dam 25, Mississippi River written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lock and Dam 25 is located on the Mississippi River, 241.5 miles upstream of its confluence with the Ohio River, The principal existing structures are the main 110- by 600-ft lock located along the right descending bank, an incomplete auxiliary lock located riverward of the main lock, and a 1,296-ft dam with fourteen 60-ft tainter gates and three 100-ft roller gates. An overflow dike with top elevation of 434.0 (elevations (el) are in feet referred to the National Geodetic Vertical Datum) extends from the dam to high ground on the left bank. The dam provides a navigation pool that extends upstream about 32 miles to Lock and Dam 24. The dam is operated to maintain a navigation pool that varies from el 434.0 to 429.7 at the dam and from el 434.0 to 437.0 at Mosier Landing (river mile 260.3). As the riverflow increases, the gates are raised to prevent exceeding the limits at Mosier Landing. A fixed-bed model reproduced about 3.7 miles of the Mississippi River and adjacent overbank from about 9,800 ft upstream to about 9,600 ft downstream of the existing dam to an undistorted scale of 1:120. Four locations are being considered for a new lock at Dam 25. The model investigation was concerned with evaluating navigation conditions for each lock location and identifying any needed modifications to the navigation channel alignment, guard wall lengths, or remedial structures. This information will also be used in the preliminary design of locks at other dam sites along the upper Mississippi River. Results of the investigation revealed that with all locations, realigning the navigation channel upstream of the lock and adding a ported upstream guard wall would reduce the outdraft, eliminate the need for a helper towboat, and improve navigation conditions for tows entering and leaving the upper lock approach.