Portable dredge readily removed the sludge from the lagoon which followed an effluent clarifier at the Dalton, Mass. site of the Crane fine and currency paper mills
Crane and Co. was faced with the problem of cleaning an effluent lagoon that was nearly filled with sludge. After some experiments with “home-made” equipment Crane decided to use a portable dredge produced by the Mud Cat Division of Mud Cat International to clean the lagoon used by Crane’s five paper mills. Discharges from the mills are piped to a central installation, where they are passed through a flocculator and then a clarifier. The water is then sent through a lagoon before entering the Housatonic River.
Over the past few years sediment has built up in the 300 ft. by 100 ft. lagoon, decreasing the water depth from 11 feet to 10 inches or less. “We had to clean the pond, there’s no question about it,” said Fred Crane, director of research and development for Crane and Co. “If there hadn’t been a Mud Cat, we would have had to sit down and build ourselves another machine.” The company had tried earlier to build its own small-scale dredging machine. “We had a raft, a submersible pump and a bunch of gadgets.” said Mr. Crane. “We fiddled around but we weren’t getting anywhere.” That’s when they decided to give Mud Cat a try.
The Mud Cat machine, a small dredge 8 feet wide and 39 feet long, can be operated by only two people, one to run the machine itself and the other to handle such shore duties as moving pipes and cables.
Powered by a 175-horsepower diesel engine, the Mud Cat is moved form side to side by means of cables anchored on shore, cutting up to 18 inches of sediment on each pass of its 8-foot-wide auger. The machine can reach a depth of 15 feet. An auger assembly at the end of a hydraulically-operated boom is lowered into the water during operation, turning and forcing waste material into an intake tube. The material is then pumped through a discharge pipe to a designated area.
The sludge can be pumped to a distance of half a mile, but in the case of Crane, the area was a drying bed only 1250 feet away.
Rather than purchase a machine for the relatively-small lagoon-cleaning project, Crane and Co. contracted for the Mud Cat services through a local contractor.
How dredge worked
When the machine arrived in Dalton, it was lowered into the water by a crane, a procedure that took less than one hour. Because of the usually shallow water level, the Mud Cat had to cut its way into the lagoon, winching ahead slowly into almost solid material.
The Mud Cat began pumping at 10:00 p.m. on March 5 and operated around the clock until March 7, when the cleaning job was completed.
The unit pumped an average of more than 150 cubic yards of material per hour, finishing the entire project in 49 hours. A total of 8000 cubic yards of material was removed, leaving the lagoon a uniform 11 feet deep. Though the use of its tiltable auger, the Mud Cat was able to clean even the sloping sides of the lagoon.
Mud Cat Division of Mud Cat International