For decades, the United States has imported far more oil and gas than it has produced, but the natural gas reserves found in shale deposits throughout the country have the ability to change that. In fact, the nation is expected to become a net exporter in less than two years.
One of the country’s largest energy companies is supporting that transition by completing a $3 billion conversion of its East Coast import facility to a liquefaction and export plant capable of producing more than five million metric tons of liquid natural gas (LNG) each year. KCI worked with the construction manager to design the utility and roadway changes necessary to move oversized pieces of equipment integral to future plant operations from barges to the construction site.
The process of liquefying natural gas, which involves cooling it to -260 degrees Fahrenheit, requires a complex industrial operation. The construction manager had many of the necessary components built overseas and shipped to East Coast ports, where it was transferred to barges for the next leg of the journey—an over-land route from a temporary pier to the construction site. KCI helped the construction manager prepare the six-mile stretch of two- and four-lane roadway for the oversized equipment moves, a first for KCI.
Because the plant equipment ranged anywhere from 60,000 to 800,000 pounds in weight, and between 20 and 156 feet in length, the moves were considered superloads—freight that is too long, too heavy, too wide and/or too tall to be moved via regular tractor trailer delivery. Instead, the construction manager worked with specialty subcontractors to utilize multi-axle transport vehicles capable of dispersing the weight of the oversized shipments.
Engineers had to analyze and define a specific heavy haul route as well as design roadway improvements and utilities relocations along the designated path in order to move each component safely and without incident from the pier to the construction site. “By coming to KCI, they got it all,” said project manager Richard A. MacInnes, PE. “Our relationships with the utilities and with the state, as well as our expertise in surveying and geotechnical, roadway, environmental, water resources, structural and utilities engineering, played important roles in identifying and permitting the heavy haul route.”
Utility relocations were an early action item because poles lining the proposed route carry telecommunications, power and cable wires both alongside and crossing above the driving lanes. The height of many of the pieces of freight, one nearly 30 feet tall, threatened to damage overhead infrastructure. The KCI team worked with Comcast, Verizon and the Southern Maryland Electric Cooperative to develop three separate sets of construction documents for each of the 24 utility crossings that had to be moved underground.
As construction progressed on the utility relocations, the KCI team began detailed studies of the proposed haul route. A comprehensive subsurface exploration determined that no major pavement reconstruction efforts were required to support the heavy loads, saving millions in both cost and schedule extensions. Roadway surfaces and what lies beneath are designed to accommodate a specific amount of weight from vehicles above—anything more can lead to pavement failure. A combination of drilled cores, standard penetration tests and radar surveys confirmed that the asphalt and soils along both routes could accommodate the expected weight from the heaviest plant components as they slowly travel along the roadways.
The team also began to analyze different aspects of the route to confirm the feasibility of moving the oversized equipment. “We did a number of analyses with the longest combinations of length, width and height to prevent unknowns from popping up,” said construction manager Dave Andrews. Roadway engineers contacted the heavy haul carrier to gain better insight into the specialized movers to be used.
Project engineer Dion K. Ho, PE, used AutoTURN, a program that simulates turning movements for different sized vehicles, to help ensure that each delivery could follow a designated path, whether the equipment was more than 150 feet long or 20 feet wide. “These big vehicles can’t make sharp turns,” he explained. “AutoTURN didn’t account for a virtual 19-axle transport vehicle, so we used a more conservative model in our analyses.”
The final route took the movers back and forth across the highway to avoid signalized intersections and existing utility poles, and even required the trailer to be directed onto a side road, unhitched, and then pulled from the opposite end to navigate through a turn lane and on toward the construction site. Two median crossovers and several areas of pavement widening had to be built as well as two signals relocated to accommodate the superloads.
The goal was to create a path for the large equipment that would avoid as many signal and utility crossings as possible by moving to the opposite side of the road.
Dion K. Ho, PEProject Manager
The heavy hauls and associated overnight road closures began earlier this year. “We went into the field with a lot of certainty,” said Andrews. “We knew there would be areas that would be tight, but they could make the pass without taking out a pole, a sign or a signal.” In one area, just inches separate the widest loads from the poles adjacent to the roadway.
Even with such tight constraints, the equipment moves are proceeding as scheduled, and construction is moving forward on the East Coast’s first LNG export facility. By the fall of 2016, all 70 heavy hauls will be complete, and the contractor will begin reverting roadway changes associated with the project, including the median cross-overs, back to their original state.