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Underpinning a Section of Steel Pipeline
Author(s) -
Gunther Harold L.,
Noll Dean C.
Publication year - 1961
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.1961.tb00663.x
Subject(s) - welding , levee , section (typography) , geotechnical engineering , engineering , swamp , pipeline transport , geology , mechanical engineering , ecology , advertising , business , biology
The Ramapo force main is a steel pipeline built to increase the yield of the Wanaque Reservoir, at Wanaque, New Jersey, by 25 mgd. This is accomplished by pumping water through the main from the Ramapo River at Pompton Lakes, New Jersey, to the reservoir. The main is approximately 5 mi long. Construction was started in 1951 and completed in 1953. The main can carry the full capacity (100 mgd) of the new Ramapo pumping station under a head of 115‐135 ft. It was made in sections 40 ft. long, except for curved and special sections, and was fabricated from two 176‐in. steel plates welded together longitudinally to form the 72‐in. ID pipe. All transverse joints were butt welded in the field, except that a coupling was substituted for the weld at approximately every 1,000 ft throughout the entire length of main to provide for contraction of the steel. In order for the contractor to bring in the pipe lengths, it was necessary for him to build a 3,700‐ft access road through a rugged swampy area. The road was built parallel and adjacent to the line of the pipe. The contractor dumped into the swamp approximately 4,000 cu yd of excavated rock and built the road on top of the rock. Four years after completion, it was noticed that the access road and the pipe embankment had both settled. When levels were run along the top of the embankment, it was found that the pipe had settled 4 ft below the installed grade and to have shifted laterally 9 in. out of line at approximately the midpoint of the swamp. The pipe had pulled apart a distance of approximately 3 in. at the coupling without leaking. It was decided not to jack the pipe back to its original position but to underpin and secure it in its settled location. During the designing of the pipe‐carrying supports, there arose the peculiar problem of attempting to bridge a swampy area 280 ft long with a 72‐in. ID main that had a 3‐ft. earth cover. When the nature and depth of the swamp were known, stress analyses was done. The article discusses this analyses in detail, along with unbalanced loads, and the materials used on the project.