Scoop Up 150 yd/hr of Silt from Cyanamid's Coagulated Water Pond
Small barge outmaneuvers bigger unit in dredging operation
A filtration removal device for separating river silt from a coagulated water pond at American Cyanamid Company's Bound Brook, N. J. plant proved to be faster, cleaner, quieter and cheaper than a huge dredge 2-3 times its size previously used. Some 12,000 yds of material was removed in 10 days, operating 12 hours per day for an average production including downtime of 100 yd/hr. Several calculations show material removed at approximately 150 yd/hr.
Earlier dredging necessitated isolation of pond from plant operations. According to Project Engineer Jules Mujica, the smaller machine did not require such isolation, but went right into the heavy river silt and pumped it out without great agitation.
The larger dredge took approximately one week to mobilize, 2 weeks to dredge and 1 week to demobilize. The small machine took about an hour to launch, and about half an hour to lift into an adjacent pond.
The spoils area was 2700 ft from the ponds. It measured 250 ft x 650 ft and held 24,000 yd3, or twice the volume of material removed.
The pipeline traveled past the plant office building, through a railroad culvert, over a parking lot, making a turn of 180 (two opposite 90 turns forming a "Z"), increasing about 10 ft in elevation. No leakage occurred during pumping operations. Cyanamid's people commented on the clean transmission of material.
The pond was 200 ft x 350 ft with silt projecting through the water in some areas. Prior to cleaning, pond contained only 25% to 30% of its original storage capacity. After cleaning, the pond had 8 ft to 10 ft of free water. Cleaning took place with ponds on-line supplying process and boiler feed water on a continual basis. Low turbidity allowed this. Dredges had previously cleaned these ponds, but ponds had to be taken off-line because of excessive turbidity due to dredging operations.
Sedimentation was clayflocculated from river water. The 1" pipe probe pole work would settle down through the soft material by its own weight. When the barge took a cut, the material would stand. The machine made cuts of 2 ft depths.
Spoils contained 40% to 50% solids by volume. Settling took place in about 600 ft of flow down the 250 ft wide spoils basin. A decant chamber with removable weir boards was used to assure that the solids were contained in the basin.
Reprinted from Pollution Control
