Model studies of water requirements and salt-water intrusion, Intracoastal Waterway, New York Bay-Delaware River Section
U.S. Army Engineer Waterways Experiment Station.
Technical memorandumSynopsis: This memorandum is a comprehensive report on a series of hydraulic model investigations of the hydraulic design and the plan of operation of locks and appurtenant structures for the prevention of salt-water intrusion from New York Bay into the proposed New York Bay-Delaware River Section of the Intracoastal Waterway (hereinafter referred to as the New Jersey Ship Canal) and thence into the Delaware River. These model studies were authorized by the Chief of Engineers, U. S. Army, on 9 December 1943, and were conducted at the U.S. Waterways Experiment Station, Vicksburg, Mississippi, during the period January 1944 to May 1945. The proposed New Jersey Ship Canal would extend across the State of New Jersey, from Sayreville at the head of Raritan Bay to Bordentown on the Delaware River, a distance of approximately 33 miles. The proposed route for the canal is shown on plate 1. As planned at the time of undertaking these studies, the canal would have a depth of 22 ft below mean low water and a normal pool elevation of 10 ft above mean low water and would be equipped with two parallel ship locks and one yacht lock at the-Bordentown or Delaware River end, and one ship lock, one barge lock, and one yacht lock at the Sayreville or New York Bay end. For the purposes of this study, three models of the New York Bay end were used: (a) a 1-to-60-scale model of the Sayreville Locks to determine the volume of salt which navigation would cause to intrude into the upper pool through the locks, and to investigate methods of eliminating or reducing such salt intrusion; (b) a 1-to-150-scale comprehensive model of the locks and upper-pool canal to determine the extent to which the salt brought in through the locks, in amounts determined from operation of the 1-to-60-scale lock model, would intrude into the upper pool and canal toward or into the Delaware River; and (c) a 1-to-20-scale model of the ship lock to determine whether the hydraulic design and method of operation of the locks found satisfactory from the standpoint of salt-water elimination would also be satisfactory from the standpoint of navigation requirements, and to investigate the possibility of scale effects in the l-to-60-scale lock model. The principal conclusions drawn from an analysis of the results of all model tests follow: a. The prevention of salt-water intrusion through the Sayreville Locks into the upper pool and canal can be accomplished by flushing the lock chambers with fresh water each time the lock chambers a.re raised from lower-pool to upper-pool elevation. With a salinity of 13,000 ppm below the locks, one-half lockful of fresh water for each flushing will be sufficient to hold saltwater intrusion to tolerable limits. b. Essential features in the reduction of salt-water intrusion are: high filling ports and bottom emptying ports; impermeable 1500-ft guide walls in the upper pool; location of the lock-filling intakes in a deep sump between the upper-pool guide walls; and scavenging with a comparatively small volume of water from the bottom of a deep sump outside of but in the immediate vicinity of the guide walls. c. The total fresh water requirements during the maximum traffic schedule for operation and flushing of the locks with one-half lockful of fresh water and scavenging with 25 cfs will be approximately 354 cfs. d. The revised hydraulic design and method of operation of the locks and appurtenant structures found in these studies to hold salt-water intrusion through the locks to tolerable limits will also be satisfactory from the standpoint of navigation requirements, provided that filling and emptying times of not less than 6 and 5 minutes, respectively, be used during operation of the lock hydraulic system. Shorter filling or emptying times will result in hawser stresses which might be objectionable.
U.S. Army Engineer Waterways Experiment Station.Engineer Research and Development Center (U.S.)
Saline water barriers; Locks (Hydraulic engineering); Canals; Intracoastal waterways; Hydraulic models
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