Compact HDD Installations Available From Keyhole

February 2012, Vol. 67 No. 2

TT Technologies has developed an ultra-compact horizontal directional drilling unit designed to operate from a keyhole excavation to install natural gas and water service installations.

The Grundopit-K is positioned in a 24-inch diameter keyhole excavation to install services to 2½ inches in diameter to distances of 100 feet, said Chris Brahler, TT Technologies president.

The new machine was exhibited at the recent 2012 Underground Construction Technology International Conference & Exposition and is now available to the market.

Keyholing -- making a small, precisely-controlled excavation to access underground pipe or equipment for repairs and maintenance -- has been used for many years, but recent advances in technology and equipment have expanded the applications that can be accomplished by keyholing.

“Demand for the Grundopit-K was driven by our customers in the gas industry who wanted a trenchless way to install service lines,” said Brahler. “The whole process is automatic. The operator simply loads drill stem and activates the system; software guides the whole cycle. This system offers the ability to reduce the size of an excavation needed to install new or repair services and subsequently saves significant financial and environmental resources.”

Typical install
For a typical installation, Brahler said a 24-inch diameter core is removed at the surface and soil is vacuum excavated to the depth required to initiate drilling for the service installation. The drill head/sonde housing is installed into the drill unit which then is lowered into position inside the excavation and secured using four hydraulically-actuated stabilizers. The drill unit contains an automated rod handling system which transports nine-inch long-rods from ground level down to the drill head where they are positioned for horizontal drilling.

“With the Grundopit-K’s automated drilling feature, the operator simply loads rods into the handling chamber and at the press of a button the rod is lowered and loaded into the drill head,” said Brahler. “The drill process can be done in an automatic mode for straight bores and can be switched to a manual mode when steering corrections are needed. Standard tracking equipment is used to monitor the bore path.”

Hydraulic power is supplied by a dedicated power pack or on-site equipment such as an excavator.