A kind of pile-driving machine not commonly found in North America is helping Edward E. Gillen Company achieve high efficiency on a variety of its projects both in Wisconsin and Illinois.
Gillen purchased the unit, a telescopic-mast piling rig called an ABI Mobilram system, from ABI's dealer in the area, Hammer and Steel, Inc., St. Louis, MO.
According to Hammer and Steel salesman Mike Ormsby, there are fewer than 100 of the units in the country, though they are well accepted in Europe. Gillen owns the only one in Wisconsin.
General Superintendent Tom Miller says Gillen selected the telescopic-mast piling rig because a similar unit had proven valuable whenever Gillen had rented it for projects, mostly in Illinois.
Says Miller, "We still drive piling extensively using traditional lattice-boom crawler cranes and pile drivers. But there are many jobs in which the telescopic-mast piling rig and its attachments are the better way — and sometimes the only way — to do the work effectively."
Gillen Project Manager Paul Wiedmeyer explained, "For example, two of the vertical access shafts we built as part of a tunneling project in Milwaukee were located less than eight feet from two older buildings. To be sure we didn't disturb their foundations as we built temporary sheet-pile cofferdams for the shafts, we used the ABI unit with an hydraulic attachment to smoothly press the sheet piling into the ground. There was no vibration at all."
The ABI Mobilram telescopic-mast piling rig owned by Gillen combines a hydraulically controlled mast with a crawler-mounted carrier manufactured to ABI specifications in Germany by Sennebogen.
Some of the features that Miller mentions as being particularly suited to pile work are extra-heavy structural components; crawlers that can be pulled in tight to reduce transportation width, then extended sideward to provide a wide working base; a 650-horsepower diesel engine; an extra-heavy duty hydraulic system; and electronic controls designed to withstand vibration.
The self-erecting mast that carries the tools can be rotated backward to lay over the top of the machine for travel, then rotated upright for working. It telescopes down to 50 feet in order to minimize length during travel, and extends to 72 feet for working.
The tool carrier that runs up and down the mast permits the use of a variety of attachments, including dual-auger casing drives, drills, a CFA (augercast) drill head, diesel and hydraulic hammers, vibratory hammers and sheet-pile extractors, and the vibration-free press-in tool.
Because the traveling tool carrier makes a positive connection between the mast and the tool being used, says Miller, more energy is transmitted to the work being done. "With a typical suspended vibratory hammer, the most downward force you can get is the weight of the hammer. That's about 20,000 pounds."
"With ABI, the downward crowd force is more than twice that of a conventional suspended vibratory hammer."
Miller says the machine is also effective at extracting sheet piling. "We can pull a sheet in about 10 minutes, compared to as much as two hours with a lattice-boom crane," he says.
Says Wiedmeyer, "Ever since we've purchased the unit, it's always been busy at one or another of our projects. It almost never sits idle. The machine's ability to work with a variety of pile-handling equipment and to handle piles up to 72 feet tall make it useful on many projects."
Wiedmeyer says Gillen trucks the machine back and forth to jobs throughout Wisconsin and Illinois. For travel in Wisconsin, Gillen leaves the one-piece counterweight on.
For trips into Illinois, says Wiedmeyer, the one-piece 34,000-pound counterweight is removed to meet weight restrictions.
Either way, he says, the machine can be off the trailer, set up, and working within about 45 minutes of arriving at a job site. Setup takes two people and no assist equipment.
One of the current projects that has seen Gillen use its ABI Mobilram extensively is the Canal Street Wet Weather Relief Sewer project in Milwaukee.
The Canal Street project is part of a Milwaukee Metropolitan Sewerage District (MMSD) program to improve the system's ability to handle unusually high volumes of water that come from heavy rain or melting snow.
The Canal Street stretch of sewer connects the deep-tunnel system to the Harbor Siphons that carry wastewater to the Jones Island treatment plant.
Michels Corporation, Brownsville, WI, is the general contractor tunneling for and installing the new 84-inch-diameter sewer line.
Working under subcontract to Michels, Gillen has constructed seven vertical access shafts up to 30 feet in diameter and 36 feet deep. The vertical shafts enable Michels to lower its tunnel-boring machine to the mining level, and also permit construction of permanent manholes that will be used for inspection throughout the life of the sewer.
In constructing each of the access shafts, Gillen used its ABI Mobilram to install, and later remove, about 48 interlocking sheet piles measuring 60 to 72 feet tall and weighing about 5,600 pounds each.
Some of the piles were driven using a vibratory hammer attachment. Others in sensitive areas were pressed in smoothly using a vibration-free Z-pile pusher attachment.
Wiedmeyer commented, "Another advantage of installing the sheet piling with the Mobilram is that we didn't have to spend two weeks constructing and dismantling a 20-foot-high steel-framed template to guide these tall pilings — which we would have had to do if we'd used a suspended pile driver. That's a real time and cost saving."
After the cofferdams were completed, the insides were excavated to the required depth using hydraulic excavators and a lattice-boom crawler crane with a clamshell bucket.
Gillen then used a lattice-boom crawler crane and air-driven hammer to drive about a dozen 10-3/4-inch diameter hollow steel support pilings into the bottom of each shaft until they reached 40-ton bearing capacity. (Wiedmeyer chose the air hammer to eliminate diesel fumes from collecting in the shaft.)
Once in position, the piles were filled with concrete.
A subcontractor then poured a concrete floor atop the pilings before Michels lowered its tunneling machine into the hole and started boring.
As the tunneling is completed, a subcontractor constructs a permanent 14-foot-square access shaft at each site, and the rest of each excavation is filled with slurry backfill. When that work is complete, Gillen will use its Mobilram to remove the sheet-pile cofferdams.
Gillen expects to finish by its deadline this fall.