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Tough Crossing To A New Record: Successful HDD River Crossing Of Nearly 2 Miles
The first option was for two directional drills to be completed, with a conventional open-cut trench to tie the drills together in the Cooper River tidal marsh area, which is a designated wetland. Although this open-cut and tie-in installation method would straighten and reduce the length of the drills, it would be time consuming and environmentally intrusive: the use of conventional construction techniques in the tidal marsh would have required the stabilization of the right-of-way with several layers of matting. The tidal marsh area would have required matting as much as 1,000 feet from the west side, and high ground water would also have been an issue while conducting open-cut operations.
Upon further consideration
There was, however, a second option: a single, lengthy 9,931-foot drill, the likes of which had never been done before.
This option wasn’t without its own unique challenges due to the presence of overhead electric transmission lines and power poles. And a nearly 10,000-foot drill with a slight bend in the middle wasn’t likely to be a walk in the park, either.
Because Michels had the technical expertise and past experience drilling beneath the Cooper River bed, CGT opted for the single drill option to avoid the myriad environmental and logistical issues involved with the two-drill approach.
“In addition to the operational challenges of the open-cut portion, there were safety concerns associated with sloughing in the trench,” said Gray Lewis, vice president for Patterson & Wilder, a sub-contractor to Michels. “Working with CGT and Michels to perform one drill was a great solution that kept us from putting our workers in harm’s way altogether.”
The last Cooper River drill in 2004 gave Michels a base point to start from as they began to work on this innovative, record-breaking drill using the latest pilot-hole intersect technology.
Since their first drill under the Cooper River, Michels has continued upgrading its equipment fleet, tooling, methodology and steer technology, all of which has made a much longer crossing possible. Still, drills of nearly two miles are far from commonplace because of the need for favorable conditions at every step along the way.
To plan and execute this particular project, Michels utilized the support staff of CGT and Patterson & Wilder throughout. This team worked together to push the envelope of HDD technology and conquer yet another nearly unthinkable distance.