The following excerpt features an interview with Jason Holden recently featured in an article from Underground Construction.
Guided auger boring is probably the most popular trenchless method of construction, said Jason Holden, vice president and chief revenue officer for Akkerman. Technology for exact line and grade trenchless installations is gaining more acceptance in the trenchless community. There are many new innovations with guided boring technology that allow longer distances, more geotechnical conditions, and broader range of installation techniques.
“There are several situations that are conducive to guided auger boring,” he said. “I know of several contractors that utilize guided auger boring on every auger bore situation, whether it requires it or not. Pilot tube guides provide pin-point accuracy, which allows a smaller casing to be used since it will be on-line and grade, and there are other useful benefits.”
For example, he said auger boring projects generally do not have extensive geotechnical investigations, as they are quite costly. The installation of a pilot tube will not only give a contractor an indication of the ground type on the project, but will also provide a definitive answer, if there is an obstruction along the alignment.
Since the pilot tubes can be removed and the ground will go back to the native state, the position of the obstruction can be identified and mitigated before it is too late.
“Our GBM guidance system,” continued Holden, “utilizes a theodolite and LED target type system. It requires a line-of-sight from the launch shaft all the way to the steering head, where an LED target is located. In common terms, the guidance system acts much like common surveying technology.
“A powerful camera with remote controls is used to communicate with proprietary software that allows the operator to view the position of the steering head.”
Alternative systems, such as sonde locators, he added, are also an option for some projects that do not require exact line and grade. These systems can be used in conjunction with the standard GBM guidance systems.
Holden said the installation of pilot tubes is intended for straight line installs.
“The maximum degree of directional change is dependent upon the allowable accuracy on the project,” he explained. “The overall accuracy of the installation will be dependent upon the accuracy of the equipment set-up, which is highly dependent on the initial site survey.”
Akkerman Model 240A GBM, Holden said, can be used with any manufacturer’s auger boring system. It is a universal base frame that offers adjustability for various rail widths and centerline heights.
“We have found that this base accommodates most ABM from 36 to 72 inches. Akkerman also offers a stand-alone power pack to operate the GBM system so the contractor can utilize one GBM system with multiple ABM systems in the fleet.”
Often referred to as “leap-frogging,” contractors will install pilot tubes on one project and then move the GBM system to another site to work ahead while their ABM installs casing on the initial site.