Compact HDD Installations Available From Keyhole

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.

“Once the bore is completed, the drill head is removed using a disconnect wrench and a backreamer/swivel is installed with the product pipe attached,” said Brahler. “In the automated pullback mode, the drill handles all functions needed to backream and removes the drill string. Drill rods are pulled back and fed to the handling chamber for the operator to remove.”

TT Technologies, Aurora, IL, was established more than 45 years ago and initially supplied pneumatic piercing tools. The company has evolved into a leading manufacturer of trenchless construction equipment with a product line covered by more than 200 worldwide patents and includes pipe pulling, pipe ramming, pipe bursting, sliplining and horizontal directional drilling equipment.

TT Technologies, (800) 533-2078,

Grundopit-K Specifications

Thrust, (push/pull) 8,924 pounds
Rotational torque 625 foot pounds
Max service size 2½ inches
Drilling speed 50 feet per hour, depending on conditions
Minimum Keyhole size 24 inches
Standard depths 2 to 5 feet
Hydraulic power 6½ gpm – 2,900 psi
Basic machine weight 1,510 pounds

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