Drilling high quality granites and other igneous rocks with strengths in the range of 20,000 to 60,000 psi cannot be done with conventional tools. For this Tri-State uses a pneumatic Cluster Drill from Ingersol Rand. The picture opposite shows the water cascading out of the casing. The cluster Drill is driven by air powered by 3-1300 cfm compressors linked to the hammer.

This Cluster Drill which cuts a 48” diameter hole has 4 perimeter hammers and 3 interior hammers strategically placed in the shell. They work together spalling off chunks of rock as the drilling machine rotates the tool slowly in the hole. Production rates of 1’ to 2’ per hour were recorded for this bridge job in Wausau for the Wisconsin DOT.

Bridge piers must be drilled exactly where they are designed to go. Sometimes the river bottom doesn't cooperate. This was the case with two of the piers on the Wisconsin River in Wausau. The rock surface sloped sharply downward across the 4’ area where the hole was intended to go. This prevented the hammers from hitting it directly and caused the tool to slide.

When the going gets tough … that requires a contractor with experience like Tri-State. Constructing foundations on a waterlogged right-of-way may seem virtually impossible, but with the right equipment and planning it can be done. During the 1990 rainy seasons, these were the conditions for Santee Cooper near Myrtle Beach, South Carolina.

Tri-State's LoDrill is the perfect tool for low clearance whether it's inside a building or under existing lines that cannot be moved. Since it needs only 22’ of headroom Northeast Utilities was able to avoid outages while drilling foundations for new transmission towers along the Metro North Railroad in Connecticut.

Tight working conditions were the ruled the project on the Metro North right-of-way. Here the train is speeding past rushing passengers to New York City just a few feet from the LoDrill.

The LoDrill is also the tool of choice for reaching up and down embankments where gaining access might otherwise be very costly.