National Grid contracted Kleinfelder to provide inspection services for the Horizontal Directional Drilling (HDD) of three crossings and installation of 1,635 feet of 8-inch 24 psig High Density Polyethylene (HDPE) main gas line extension under a state road, interstate highway, and Class B stream.

Challenging Site Conditions

During the geotechnical investigation, poor geologic conditions were identified in the field that would not be conducive to a trenchless crossing. Due to unforeseen adverse ground conditions in all three crossings, one major challenge was large cobbles laterally compromising the breakaway link securing the product pipe during pullback.

Innovative Pullback Method Keeps Project on Track

Kleinfelder worked with the drilling contractor to execute a new pullback method in situ to ensure that the project remained on schedule. The method used a Tensitrak Pullback and Pressure Monitoring System in place of a breakaway link. The advantage was that the system could monitor annular pressure while also being set to breakaway at a pullback force of 10,000 lbs. Additionally, the system could transmit pullback force for the entire duration of the pull, including the highest pullback force, thus allowing the pipe to be pulled without loss and within tolerances.

Project Results

Kleinfelder oversaw the successful testing and implementation of the Tensitrak system at the two longest crossings in Schodack, totaling 1,635 feet. The system also verified that the pipes were pulled at half of the maximum allowable pull force – a solution that prevented a delay in the completion of the three crossings – saving an estimated five days.

Project Details

Location:
Syracuse, New York

Owner:
National Grid