May 2019 Vol. 74 No. 5
Features
Steering Through Sandy Soils to Upgrade City Sewer System
The economy in Garden City, Kan., is strong with the recent opening of a Dairy Farmers of America plant. Approximately 4 million pounds of milk from regional farmers makes its way to the plant each day, which has led to expansion for many other companies throughout the area. To keep up with the expected growth from the dairy industry and retail stores being constructed nearby, Garden City is upgrading existing utilities to ensure they are prepared to handle current and future needs.
Garden City’s most-recent project involves upgrading its sewer system to larger-diameter piping near the dairy plant. While most of the work is being done using open-trench methods, several road crossings require trenchless methods. To install the large casings deep underground, auger boring has been selected as the method of choice.
When specialty trenchless work needs to be done, Horizontal Boring & Tunneling Co. of Exeter, Neb., is a trusted partner that many general construction companies call in. Since 1983, Owner Brent Moore and his team have been performing underground construction work throughout the country. Horizontal Boring & Tunneling crews perform everything from auger and guided boring to microtunneling and pipe jacking across 14 states.
According to Kenton Moore, project manager, the company has been part of some huge projects.
“We don’t shy away from big pipe. We do a lot of 60-, 72-, 84- and 96-inch-diameter pipe installations,” Moore explained. “There
are not a lot of companies as highly specialized as we are, which is why we are usually called on to handle large-diameter bores.”
Project Supervisor Doug Godown and Crew Supervisor Roger Glenn spend a lot of time in Kansas performing auger boring work.
In fact, Glenn’s crew has spent most of the winter working in Garden City and the Kansas City area.
“We usually work year-round, no matter what the weather is like,” he explained. “Over the years, we’ve gotten good at staying warm and ensuring our machinery is ready to go no matter what the temperature is.”
Two-month-long project
For the Garden City sewer expansion project, Glenn’s crew was pulled in to perform four, 42-inch auger bores at depths of 12 to 13 feet in sandy soils. Bore distances were 75, 272, 280 and 383 feet long, and the bores exited into manholes at a 0.06-percent drop, so everything had to be on target.
“Over the years, we’ve done around 10 bores in the Garden City area, so we knew what to expect on this one,” Glenn explained. “Soil conditions are sandy, which makes it a major challenge to stay on-grade. Sandy soils can have air voids, water pockets and areas with sandstone. We also have to battle with the sand packing in around the casing because of the vibration in the hole.”
This project was slated to take a total of 10 weeks, but thanks to a new tool in the Horizontal Boring & Tunneling fleet, the crew wrapped everything up two weeks early.
The crew used the McLaughlin ON-TARGET auger boring steering system to keep the casings on-grade with minimal side deviation. The 42-inch steering head is welded onto the front of the first casing being installed. Crew members are then able to check and maintain the line throughout the bore, with twin-line projection LED lights enclosed in the steering head, and control the movement of the steering head—as well as hydraulic, water and electrical lines—from a self-contained control station.
Horizontal Boring & Tunneling used the system with its existing auger boring machine. “We’re familiar with McLaughlin auger boring equipment, but that’s not what we had on this job—we were using another manufacturer’s machine,” explained Glenn. “What’s nice about this system is that it will work with any auger boring machine—it doesn’t matter who made it, which makes it a pretty darn cost-effective option to add to a job.”
The ON-TARGET steering system is an upgrade to how crew members would typically handle these bores. Glenn said they would have normally used a conventional head with left and right pads and would have pulled the auger out every 40 feet to measure where they were. Then, they would adjust direction as needed, reset the auger and do another 40 to 60 feet. At 100 feet, they would also shoot the line grade.
“The conventional way is a much more time-consuming process,” he added. “The ON-TARGET system saves a ton of time—on this job a full two weeks.”
Attention to the details
The six-person crew, along with a pair of John Deere excavators, prepared for the bores by digging entrance pits. They set 32-foot trench boxes with a 15-foot spread at a depth of 12 to 13 feet for the 75- and 272-foot bores. They dug a 64-foot long pit between the 280- and 383-foot bores, since those backed up to each other. Compacted rock was used for a base in all the entrance pits.
The shorter bores were under a road that leads to the dairy plant and the driveway of a trucking company that hauls milk out of the facility. The 280-foot bore was under a state highway, and the longest shot was under a road to a sandpit.
“Interrupting everyday operations at the plant or the trucking company was not an option, which is why the project called us in,” said Glenn. “While I’m sure people knew there was an underground crew working in the area, no one had to change normal routines to accommodate us.”
After preparing each entrance pit, the auger boring machine was lowered into the ground where the first piece of casing with the steering head was added. The crews worked the shorter bores in 20-foot increments. On the longer bores, they would install 40-foot joints, which certainly sped up production rates.
“By the time we got to the longer bores, we had complete confidence in the steering system,” said Glenn. “So, we welded up two casings at a time. On the first day of the last bore, we did 100 feet, 120 feet on the second day and 160 feet on the third day. The bore went quickly.”
More important than production rates, was accuracy and quality. “This was our first time using the steering system, so I was a bit nervous on the first bore,” Glenn said. “We hit all of our marks right on target.” •
FOR MORE INFORMATION:
Horizontal Boring & Tunneling Co., (402) 266-5347, hbttrenchless.com
McLaughlin, (800) 435-9340, mclaughlinunderground.com
John Deere, (309) 748-0114, johndeere.com
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