New Tool Helps Colorado Contractor Tackle Tough Ground Conditions

August 2010 Vol. 65 No. 8

The On-Target steering head uses a built-in vertical alignment sensor that provides continuous monitoring of grade using two projection halogen lights enclosed in the steering head. Because of this, a 20-inch auger was used to ensure the crew could see the lights and maintain line throughout the bore.

On the eastbound bore passing under the railway, the crew had to deflect the bore into the receiving pit located in the eastbound lane of 124th Avenue in order to bore out of the flow of traffic and not require the closure of this busy street. In addition, the receiving pit was bordered by existing utilities to the north and a private septic system to the south.

“The steering head worked great and we hit our marks with no issues,” says Zadel. “At one point in the bore under the highway we hit hard clay and our pushing pressures went up tremendously. However, the machine and head didn’t have any issues, but the clay did affect our daily production.”

Overall, the project took six weeks to complete. In the better materials, Zadel states they were getting about 40 feet a day, but in the clay soils they were lucky to get 20 feet a day.

“I think very seldom do contractors complete one bore in two separate sections like we did on this project,” says Zadel. “I don’t think the bore could have been completed in one shot with the accuracy needed considering the existing ground conditions and other unknown factors. Overall the On-Target steering head worked well and is a cost-effective option for tight bores.”

FOR MORE INFORMATION:
McLaughlin, (800) 435-9340, www.mightymole.com
Northern Colorado Constructors, (303) 857-1754

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