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Frontier Pipeline Completes Record Setting Rock Drills
The first crossing began in April 2008 and was completed in July 2008 with only two minor inadvertent returns to the surface. The second crossing was completed on October 22, 2008, with no returns. “Both inadvertent returns were responded to immediately by Frontier Pipeline in a professional and expeditious manner which truly contributed to the success,” said John Dunham, supervising engineer for Connecticut DOT District 3A. “The skill and experience they exhibited during these events proved they were the right contractor for this extremely challenging project.”
Limited work space
Limited work space on rig and exit sides of the project proved to be particularly challenging. The drill rig had to be located on an adjacent property at the busy Suzio concrete plant. The back of the drill rig was up against a temporary access road constructed to allow concrete truck access to the plant. “Rig side was always a very busy place to be considering the coordination with the concrete plant and other contractors in the area,” explained Frontier’s Drilling Superintendent Jordan Resop.
The exit side of the crossing was also limited in that, while adequate work space was provided for drilling, operations there was not enough real estate for the drilling operations and HDPE fusion operations to co-exist. For this reason, pipe fusion was carried out on the rig side under a bridge and the HDPE product line was floated across the harbor the day before the pipe pull was scheduled to commence. Once the HDPE product line was on the exit side, it was pulled into the borehole in three separate sections.
Tight drilling tolerances
The two proposed product lines were designed to come within 16 feet of each other as they approached the exit side of the crossing. This condition, coupled with coming within 10 feet of a sheeted foundation for a high tension tower, made for a very tight fit in completing the pilot hole.
“Both crossings were, frankly, like threading a needle as we approached the exit side of the crossings,” explained Lagios.
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