Laney Find New Tech Solution For Challenging Crossing

Longest U.S. Direct Pipe Project To Date
By Jeff Griffin, Senior Editor | March 2014, Vol. 69 No. 3

“Set-up began with foundation work, welding of the product pipe and installation of an umbilical inside the product pipe,” Snider explained. “Then the pipe thruster and launch cradle were placed on the foundation. The DP machine components were assembled on the launch cradle. After the DP machine was completely assembled, the umbilical hoses and pipes were assembled inside the product pipe and welded to a transition piece attached to the TBM.”

Tunneling started after the welding was complete and all umbilicals were connected.

Due to limitations of the pipe stringing areas, the project required two pipe string sections of 702 feet and 741 feet for the construction of the crossing (additional length was required on the entry side between the DP machine and entry point). The second section was welded to the first section and X-rayed after the first section was tunneled and installed.

“To stay within the project tolerance, man-entry, in-pipe surveys were made at 700 and 950 feet,” Snider explained. “After breakthrough on the exit side, coatings on the two sections of product pipes were checked. The checked product pipe coatings were inspected and found in good condition.”

The cutting solids obtained from the tunnel were separated using a cleaning system. Solids were tested and then transported offsite to a manufacturing facility to be used to make modular blocks for retaining walls and pavers.

Laney started demobilization of the site after the product pipe passed the owner’s post installation testing.

The Aquashicola Creek project took about three and half months including mobilization and demobilization.

The overall expansion project involved the construction of 13 miles of additional 42-inch pipeline loops and additional compression and existing facility modifications.

Passing the test

Snider said Laney will use DP technology again on projects in situations where it is the best option.

“We would use DP for the crossings which are difficult to be installed by HDD,” he explained. “One of the main advantages of DP is its very low hydraulic fracture and inadvertent returns potential. Therefore, it can be used in weak soil formations where hydraulic fracture risks are high. With DP, higher factors of safety against hydraulic fracture can be achieved without increasing depth and length of the crossing.”

Williamson said Williams will consider DP technology when faced with the requirement to perform trenchless installations where the typical HDD installation process is not feasible.