Frontier Pipeline LLC, based in Somerset, WI, with engineering/administrative offices in Duluth, MN, recently completed a successful project consisting of two parallel crossings for the installation of 48-inch HDPE pipelines under New Haven Harbor in New Haven, CT.
The two utility replacement crossings were completed for the Connecticut Department of Transportation (CTDOT) as part of the replacement and relocation of the Pearl Harbor Memorial “Q” Bridge.
The Advanced Sanitary Sewer Relocation project was necessary to replace an existing sanitary sewer force main that infringed on the proposed location for the new bridge. Frontier teamed with The Middlesex Corporation (TMC) for the project, with TMC providing marine support, product line fabrication/handling, and shoreline tie-in work. The project was awarded in early 2008 and drilling began in April 2008. The first product line was installed in early July 2008 and the final pipe pull back occurred in October 2008.
One of the biggest challenges facing the HDD installation was the continuous, nearly 45 degree turn in the horizontal alignment for both crossings over a length of approximately 1,900 feet in solid rock. This constant horizontal curve, creating compound curves when combined with vertical bends in and out of the crossing, tested the limits of the pilot hole surveyor and created new limits on what can be done using maxi-rig HDD.
“To my knowledge, a crossing with nearly 45 degrees of turning over a 1,900 foot length creating a 60-inch borehole through rock has never been attempted,” said Frontier vice president – HDD operations Dimitrios (Jim) Lagios. “This should be considered a record drill and everyone involved should be proud of a truly remarkable HDD installation.”
The project specifications contained tight regulations for inadvertent drilling fluid returns to the harbor bottom. Any release was believed to pose an adverse impact on the shellfish population native to the harbor. A patient approach to the drilling and reaming processes was necessary due to the soft soils on the western shore of the harbor and the undulations in the rock stratum. Extensive engineering controls, close monitoring and containment/clean-up plans were required in order to complete the crossings.
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.
Survey coil problems
There was also difficulty in anchoring the survey coil. The crossing line of the New Haven harbor was located at a point where the Quinnipiac and Mill Rivers converge, creating fast currents that made it difficult to anchor the survey coil. Ultimately, an alternative anchoring technique was used to adequately secure the survey coil to the harbor bottom. In addition to the water current challenges, fishing activity in the area resulted in damage to the coil on several occasions. Eventually, signage and a patrol boat were employed to protect the coil from the fishing activity.
“Even with the delays experienced with the survey coil stabilization, the HDD portion of the project was completed within the budget and well in advance of the contractual completion date,” said Frontier Pipeline president Dan Baillargeon.
“This is certainly one of the largest HDD projects going on in the country.” said Dunham. “I truly believe the success of this project was due to the skill and experience of Frontier Pipeline. Frontier Pipeline exhibited considerable knowledge and expertise developing a strategy to drill and ream the 60-inch holes and developing a lay down area for the pipe which minimized the impact to the traveling public and a nearby concrete batch plant.”
The project was completed utilizing American Auger 440 and 880 drilling rigs, Century Products down hole tooling, and a mixture of Tulsa Rig Iron and Kem-Tron mud handling systems. “As a small, growing HDD company, we really need to recognize the support provided to us by the Connecticut DOT, American Augers and Century Products,” reasoned Baillargeon. “When a project like this is successful, it is attributable to the spirit of partnership from the project owner right down to the suppliers.”
Frontier Pipeline: (218) 625-8478, www.frontierpipeline.com
American Augers: Astec Underground, (800) 527-6020, www.astecunderground.com
KemTron: (281) 261.5778, www.kemtron.com
Tulsa Rig Iron: (918) 321-3330, www.tulsarigiron.com
Century Products: (262) 820-3600, www.centuryproducts.net