Skill, attention to detail, solid preparation and confidence are a few characteristics of any successful contractor. Powers Lake Construction Co. Inc., Twin Lakes, WI., embodies these important qualities and more. According to Aaron Karow, Powers Lake Construction Project Manager, everything all relates back to the goals of the company. He said, “We are always trying to improve. Our goal is to become a full service company. We really want to get to the point where, not only can we do a little bit of everything, we excel at everything we do.” It is that dedication that proved invaluable on a recent ramming project.
The project was completed for Meyer Materials, an aggregate company located in McHenry, Ill. The company was looking to expand its gravel operation. To facilitate the expansion a conveyor system needed to be installed between the new gravel pit and the crushing equipment. The company faced one major obstacle to the expansion, the crushing equipment was located on one side of State Highway 120 and the new pit was on the other.
The solution to the problem was to install a casing underneath the highway that would allow for the conveyor system to travel from one side of the road to the other without inhibiting traffic. The project was specified as pipe ramming and Meyer Materials contracted Powers Lake Construction for the project.
Karow said, “In order to install a casing under the highway we needed to use the pipe ramming method as specified by the state. The soil conditions in the area are rather sandy. An augering application was not considered because of the possibility of undermining the road. We have done numerous ramming projects in the past. This, however, was the largest diameter ram we’ve attempted.”
In order to install the required 82-inch O.D. casing 150 feet under the highway, Powers Lake needed powerful ramming equipment. They turned to Pipe Ramming Specialist Mike Schwager from TT Technologies for a solution.
Large Diameter Ramming
According to Schwager, pipe ramming capabilities continue to grow. He said, “Large diameter ramming has become increasingly common over the last five years or so. We’ve seen the diameter of rammed casings increase from 50 inches to over 120 inches and more. We’re now ramming in the 140-inch range and I expect soon that we’ll see even larger diameters. I believe our technical knowledge has contributed greatly to that, along with equipment development. But it’s contractors like Powers Lake that really help make it all happen.”
Schwager said that much of the impetus for the large diameter ramming has been parks and recreation related. Bike paths, and walking and cycling trails under rail lines and roadways have all been catalysts for large diameter ramming projects. Schwager has also been on several projects similar in nature to the one in McHenry, Ill.
All of the projects, include the Powers Lake Construction job, have required considerable planning, preparation and the right equipment. Schwager moved to secure the ramming equipment, a 24-inch diameter Grundoram Taurus, while the Powers Lake crew began readying the jobsite.
On The Job
Powers Lake crews set to work preparing the jobsite for the large diameter casing by fabricating a rail system to facilitate the ramming. The rail system consisted of a 24-inch wide I-beam set in concrete with cross beams every 20 feet. The configuration was positioned at a 1.5% downhill grade. Grade was critical to avoiding a high-pressure gas main 30 feet into the ram.
The pipe arrived on the jobsite in three sections. Each piece of the 82-inch diameter O.D. steel casing weighed in excess of 43,000 lbs. Using a 70-ton mobile crane crews moved the pipe sections into position on the rail system. Welding the sections took approximately one day per joint. After the sections were welded together, a cutting shoe was welded on the lead casing. Two 1/2-inch bentonite lines were added along the top of the casing.
According to Schwager, using bentonite on a ramming project can be very effective, but difficult as well. He said, “In this particular case, and in the case of most large diameter ramming, using bentonite is almost essential. For this ram we used two bentonite lines, one at ten o’clock and one at two o’clock. The bentonite lubricates the outside of the casing, helping reduce the soil friction. Using the right amount and delivering it properly is based on years of experience. Keeping the bentonite line in place during ramming represents one of the biggest challenges.”
The Powers Lake crew was meticulous during set up, a quality trait Karow considers essential. He said, “Set up is always key to the successful completion of a project. When you have time to prepare and get ready; and you’re not rushed or forced to hurry and make mistakes, those are the ingredients to success.”
Next, crews used the crane to place the Taurus ramming tool in position and made the connection between the tool and the casing. A series of ram cones were used to accomplish this. An 80-inch diameter ram cone reduced the overall diameter from 80 inches to 31 inches. A second ram further reduced the overall diameter from 31 inches to 24 inches to make the connection with the tool. Two Ingersol Rand 1300 CFM compressors were connected to the tool and ramming was ready to begin.
The Tale Of The Tape
At a total weight of 129,000 lbs., ramming the 150 feet of 82-inch casing was no easy task, even for the former world’s largest pipe ramming. At the 92-ft mark the Taurus was removed and sent on to another jobsite. Schwager then brought in the reigning world’s largest pipe rammer, the Grundoram Apollo.
Schwager explained, “The Taurus was scheduled for work elsewhere and being in such close proximity to the TT Technologies facility, we were able to bring in the Apollo to finish up the project without missing a beat.”
According to Schwager, the Apollo is expected to push the limits of pipe ramming diameters into the 160-inch range. The 32-inch diameter tool has a 36-inch rear flair and measures 173 inches in length. It weighs 25,500 lbs., and delivers over 29,000 ft-lbs. of impact energy at 180 strokes per minute. Introduced earlier this year, the Apollo takes the title of the world’s largest pipe rammer from the Grundoram Taurus.
The Final Push
The Powers Lake crew removed the 24-inch diameter ramming tool and removed some of the spoil from the installed casing before moving the Apollo into position. Once all the connections were made with the new tool, ramming was underway. Within two and a half hours the remaining 58 feet of the casing was installed on grade.
Karow said, “I believe everyone was really impressed with the project. It was a big ram. Meyer Materials was very happy to have the casing installed on line and grade and we were pleased to be able to successfully complete the project.”
by Jim Schill
Trenchless Technology, November 2003