December 1, 2008Frontier Pipeline LLC, based out of Somerset, Wis., recently completed a successful project consisting of two parallel crossings for the installation of a 48-in. HDPE pipelines under New Haven Harbor in New Haven, Conn. 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 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 Corp. (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. The first product line was installed in early July and the final pipe pull occurred in October.
Frontier faced several challenges during the project. 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 ft. 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 by using maxi-rig.
“To my knowledge, a crossing with nearly 45 degrees of turning over at 1,900-ft length, creating a 60-in. borehole through rock has never been attempted,” said Frontier Pipeline 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.”
Project specifications contained tight regulations for inadvertent drilling fluid returns to the harbor bottom. Any release of drilling fluid was believed to impact shellfish populations native to the harbor bottom. 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 HDD crossing began in April and was completed in July, with only two minor inadvertent returns to the surface. The second crossing was completed with no inadvertent returns.
The drill rig and exit side work areas were limited in work space. The drill rig was located on the property of the busy Suzio concrete plant. The back of the drill rig was up against a temporary access road constructed for 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 drilling superintendent Jordan Resop. “Overall, it was pretty impressive to see success in coordinating all of the different activities.”
The exit side of the crossing was also limited in that, while adequate work space was provided for exit side drilling operations, there was not enough real estate for the drilling operations and HDPE fusion operations to co-exist. For this reason, the fusing operation took place on the rig side under the bridge and HDPE product line was floated across the harbor the day before the pipe pull. Once the HDPE product line was on the exit side, it was pulled in the borehole in three separate sections due to the lack of working space to lay out the entire pipeline segment.
The two proposed product lines were designed to come within 16 ft of each other as they approached the exit side of the crossing. This condition, coupled with coming within 10 ft of a sheeted foundation for a high tension tower, made for a 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.
The crossing line of the New Haven harbor was right at the point where the Quinnipiac and Mill Rivers converge, creating some very fast currents that proved difficult to anchor the survey coil. An alternate anchoring technique was required to adequately secure the survey coil to the harbor bottom. In addition to the water current challenges, fishing activity in the area damaged the coil on a few occasions. Eventually, signage and a patrol boat were employed to protect the coil from damage due to 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 John Dunham, supervising engineer Connecticut DOT District 3A. “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-in. 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 using American Augers 440 and 880 drilling rigs, Century Products down hole tooling and a mixture of Tulsa Rig and KemTron mud handling systems.
Melvern E. Olson is vice president of engineering and construction management at Frontier Pipelines LLC, based in Somerset, Wis.