In Lordsburg, New Mexico, a sewer line relocation project is underway to help accommodate Union Pacific’s plans for future railroad expansion. The job entails installing four new sewer pipes under existing railroad tracks and a highway. While this project isn’t a typical major sewer rehabilitation, its location and the need for accuracy makes it a challenging assignment. To get the job done, crews are relying on one of the oldest and most reliable trenchless methods — auger boring.
To complete the project, Morrow Enterprises, of Las Cruces, New Mexico, was selected. In turn, Morrow relied on the expertise of McLaughlin Underground, a Vermeer Company and a NUCA Bronze National Partner. Located in Greenville, South Carolina, McLaughlin is a tooling company specializing in underground construction with nearly 100 years of experience.
The contractor is performing four challenging underground crossings, including a 24-in. diameter, 440-ft bore, a 24-in. diameter, 130-ft bore, a 42-in. diameter, 220-ft bore and a 24-in. diameter, 350-ft bore.
“Making sure everything is set up correctly is the most important part of an auger boring job,” Morrow’s Utilities Superintendent Justin Sparks explained. “Everything needed to be on-grade for this, and there was a very low tolerance for any deviation, which meant our pit floor had to be dug to the right depth, and we needed to stay on target with the bore path.”
Setting up an auger bore starts with potholing existing utilities, digging entrance and exit pits, pouring a concrete slab for the auger boring machine, setting up the tracks and then dropping in the machine. The utility crew is using two different size units on this job, a new McLaughlin MCL 54/60 auger boring machine for the 42-in. diameter bores and its older but reliable McLaughlin MCL 24 auger boring machine.
Trying something new
For this job, crews are trying something they have never used before, the McLaughlin On-Target steering system. According to Morrow Enterprises President Leonard Morrow, one of the aspects he’s never liked about auger boring is not knowing precisely where the casing is in the ground. “Even with other steering systems we’ve used, or we made ourselves, there was always a chance of being off, sometimes it could be by as much as 7 ft,” he explained. “For us, that’s not close enough. So, when we heard about the McLaughlin On-Target system, we decided to give it a try.”
The McLaughlin On-Target steering system’s first test on the Lordsburg job was the 440-ft bore under railroad tracks using a 24-in. head and an MCL 54/60 auger boring machine. The crew executed the job perfectly. At 300 ft, the length of the tunnel, there was absolutely no grade deviation, and the line was perfect. The team continued to push to a distance of another 140 ft to eliminate the open-cut and was off grade by only 0.25-in. and within 1 in. of the line.
“We are thrilled with the On-Target steering system,” said Sparks. “It was easy to check where we were at and make adjustments. Every time we pulled the auger back, we could check the position of the twin line projection lights. It’s pretty exact. With other systems, we just didn’t know, we were guessing.”
After that bore was completed, the crew flipped the auger boring equipment around in the same pit to complete another 140-ft bore under the highway and then connected the casings in the pit.
Representatives from McLaughlin Underground were on site for the first job, which Sparks says he greatly appreciated. “With this being the first time using the On-Target system, having them there was helpful,” he explained. “They made sure we had everything connected correctly and provided direction when we needed it.”
For the next bore, crews are using a larger 42-in. On-Target steering head to go 220 ft. Once the casings are installed, the crew will run a 24-in. diameter sewer pipe through it.
“The pit on the bore is between 9 and 10 ft,” Sparks explained. “It took about half a day to dig it out, pour our pad and let the concrete set for a couple of days. After that, we set the tracks and got to work. So far, everything has been going smoothly. We’re expecting the results to be similar to what we did on the last bore.”
The final 350-ft bore also needs to be on-grade and will house a 10-in. sewer line.
Renting and buying
With the success they had using the McLaughlin On-Target steering system, Morrow and Sparks decided to purchase the 24-in. On-Target steering system. “That’s a pretty common size casing on auger boring projects, so we know it will be used often,” Morrow explained. “Last year, we had a project where we did 42 bores that were 24-in. in diameter.”
Since there isn’t as big of a demand for 42-in. bores, Morrow Enterprises chose to rent that head. “Having the option to buy or rent directly from McLaughlin is beneficial,” Morrow added. “They get it to us when we need, and if we need on-site support, they will send someone out. It’s a great partnership.”
Reed Munro is Marketing Coordinator for McLaughlin Underground, a Vermeer Company.