Contractors, municipalities, DOTs and others who specialize in the laying of pipe or cable have long been hindered when encountering a rock layer of any significance. Traditional tools such as hydraulic hammers are slow, cumbersome and, in many cases, grossly ineffective. Blasting is becoming ever increasingly regulated and, in even modestly populated areas, is no longer even an option. As a result, production rates plummet, equipment wear rises and, if the presence of rock has not been anticipated, schedules are literally thrown into chaos.
In a recent project involving the laying of more than 3,353 meters (11,000 ft.) of sewer and water pipe for a new development, the Buffalo, NY, Sewer Authority, was confronted with a massive presence of rock — in some cases, a layer as thick as 2.4 meters (8 ft.). Unlike past projects however, by job’s end the authority this time found itself looking at a schedule completed months ahead of schedule, a situation made possible by the use of a powerful hydraulic attachment from Genesis, the Cyclone processor.
Pipe at a Price
The project involved laying water and sewer lines, excavating manholes and installing a retention pond for a new 31-home development. Work started in mid-August and, according to Bob Logalvo, inspector for the city of Buffalo Sewer Authority, was anticipated to be a real challenge, given the material into which the pipe had to be laid.
“This area, like most of Western New York, is heavily laden with rock. The rock layer rises and falls, so we can be putting pipe into a two-foot thick layer of rock and then quickly see that thickness increase to as much as eight feet. In the past, that would have meant using a hammer to chip away at the layer to get down to the minimal six-foot depth we need. We know from experience how slow that process is and we were prepared to work well into the following spring to get the pipe in. We certainly weren’t anticipating getting through as quickly as we did,” he said.
Logalvo said in an eight week period, the Cyclone has been the key tool for laying 884 meters (2,900 ft.) of 20-centimeter (8 in.) pipe for sanitary sewer use; 914 meters (3,000 ft.) of 25-centimeter (10 in.) water pipe; 506 meters (1,660 ft.) of 30-centimeter (12 in.) pipe for catch basin lines that connect to the manholes; 66 meters (215 ft.) of 38-centimeter (15 in.) storm sewer; 183 meters (600 ft.) of 46-centimeter (18 in.) storm sewer; 110 meters (360 ft.) of 61-centimeter (24 in.) storm sewer; and 953 meters (3,125 ft.) of 122-centimeter (48 in.) HDPE for use in the on-site retention pond. “We were grinding manholes measuring 6-foot and 10-foot square in 6-feet of hard rock in as little as an hour. Using a hammer, each manhole would easily be a full day’s work,” he said.
Rotating to Profit
Mounted on a 40,823-kilogram (90,000 lb.) excavator, the Cyclone is a rotary attachment which uses pin-on carbide teeth to grind material with which it comes in contact. On the William B. Price project, sizes of the processed material have been generally in the 5- to 7.6-centimeter (2 to 3 in.) range. The size of the material, however, can be altered by changing the rotation speed of the attachment, the number of teeth, the size of the teeth, their configuration, or any combination of these factors.
This ability to provide a small after-process product has been invaluable at the Buffalo site, said Bill Sams, sales representative for STI Equipment, which provided the Cyclone.
“If this contractor were to use a hammer to get through the rock, it would, first of all, be a far slower process. In fact, one day when we were not able to be on site with the Cyclone, the contractor had to revert back to using the hammer. After five hours they had laid one 20-foot section of pipe. We have regularly been laying sections that size in about 30 minutes. In addition, material from the hammer is large in size, unusable as fill on site and needs to be hauled away, adding time, the cost of trucks and drivers, and a disposal fee to the picture. We generate material that is simply pushed back into the ditch once a one-inch base and some two-inch rock has been added. So there is an added savings in not having to bring in the volumes of fill normally needed. All these add up to a dramatic reduction in overall costs, Sams said.
Getting Into Hard Rock
The material into which the pipe was being laid at the Buffalo site is predominately limestone with a cap rock heavily laden with dolomite. Hardnesses of the material measure in the 42 to 43 range on the LA hardness scale — extremely stout and abrasive said STI’s Sams.
“’The carbide teeth have shown excellent wear characteristics despite the abrasive nature of the dolomite. That is due, in part, to a water misting system located just above the drum which serves both to keep the teeth lubricated and act as a dust suppressant. The Cyclone has also achieved tremendous production rates working in concrete and rebar, in quarry applications — almost anywhere it’s worked, it’s impressed.
Logalvo added, “Since word got out about this attachment and the production rates it was getting in rock, there has been a steady stream of contractors and others interested to see what it can do. I can’t see how anyone could have walked away disappointed; it has definitely impressed us.”
(This article appears courtesy of Genesis Equipment & Manufacturing Inc.)
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