Northbrook Contractors located in Peekskill, NY was awarded the Rumbrook-Knollwood Interconnection Water Transmission Main in Greengurgh, NY. The water main route required crossing the Sprain Brook Parkway. Arcadis Engineering specified for a 200 feet of 48" steel casing sleeve to house the 24" water main carrier. 

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The location of the bore was in an obvious fill zone from the topography of the parkway. In addition the boring logs and geotechnical report indicated the presence of boulders and cobbles. Only two borings were taken to support the anticipated ground condition along the bore path. One at the entry pit and the other at the exit pit. Therefore leaving the majority of the bore path unknown. This is not an uncommon in projects where there is limited area to set up machinery to perform vertical bore samples. To verify the ground conditions. 

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Northbrook understood the risk of employing traditional auger boring methods. Where boulders and cobbles would have brought the project to a stop. Contractually a change order would have to be submitted. And then hand tunneling would have to be employed to advance the casing past the cobble and boulder obstructions. Where 3 to 5 feet per shift of production are typical for hand tunneling. This would have placed the project over budget and past the scheduled completion date. Furthermore, change orders are not always granted from the engineers and project owners. 

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An interesting fact is that Bortech and Northbrook have some history together. In 1995 Northbrook sub-contactors were unable to complete a trenchless highway crossing using both directional drilling and auger bore method. Robert Titanic of Bortech offered a solution to the mixed ground formation. The solution was to build a down the hole hammer system. Also know as DTH. It took 3 months for Mr. Titanic to build it. And the project took one week to complete. The choice was obvious to contract Bortech for their current project under the Sprain Brook Parkway.

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