Marsh Magic

LNG contractor raises tank roofs on cushion of air

By Angelle Bergeron

Everything about the Cameron LNG facility is big.

The $750 million capital investment by Sempra LNG is no small change. The 1.5 billion cu ft per day of natural gas the facility will deliver by late 2008 will be even bigger if Sempra receives approval to expand, adding another 1.15 bcf per day. The 35 mi of pipeline reaching from the Hackberry, La., facility to a major junction will provide access to a hefty 65% of U.S. gas markets.

Even construction of the LNG facility is huge, from the equipment required to build the facility to the 140,000 tons of limestone placed on the marshy site to elevate it to plus 5 ft.. 

“It’s just big - big tanks, big docks and big ships,” says Jerry Cochran, construction director for Aker Kvaerner of Houston, lead partner in the joint venture with IHI Inc. IHI is responsible for the design of the full-containment storage tanks and Aker Kvaerner is handling the balance of the plant, including construction of two ship berths/unloading docks, process units, pipe racks, control buildings and the mechanics and instrumentation of the cooling process.

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“The pipeline is the responsibility of Sempra Pipelines & Storage and will be constructed by their contractor,” says Art Larson of Sempra Energy media relations.

Cameron LNG is situated on the Calcasieu Channel, 18 mi from the Gulf of Mexico and surrounded by marsh and wetlands. Aker Kvaerner received the notice to proceed Aug. 5, 2005, and the contractor began by setting up a temporary facility on 14- or 15-ft-elevation of dredge spoil that had been created by the Corps of Engineer’s dredging of the channel.

“We laid geo-grid right on top of the marsh and started placing rock on it,” Cochran says. “We brought barges in, started unloading it, dumping and pushing the rock.”

This build-as-you-go process was interrupted when hurricanes Katrina and Rita hit in August and September. The contractor didn’t really suffer any physical damage to equipment or materials because the only thing onsite was rock.

“The fallout of the hurricane did more damage than anything,” Cochran says. “We lost about two weeks because they had set up a road block and we couldn’t get back in. And the labor situation meant we had to set up temporary camps for subs to get people out here.”

The contractor currently has about 500 employees onsite, and employees live in nearby trailer parks or commute from Orange, Sulphur or Lake Charles, Cochran says. “We’ve got close to a hundred living in the Hackberry area,” he adds.

Obtaining skilled labor hasn’t been difficult thus far, but the contractor is hoping it doesn’t become a problem at the end of the year, when the project will be at its peak. “There are so many projects coming around, including LNGs at Sabine Pass and Chenier, and Motiva will kick off soon with an expansion,” Cochran says. “When you get a bunch of competing wage rates, it’s so competitive.”

Everything onsite is built on prestressed concrete piles, ranging from 40 to 110 ft. Bomac Inc. of Beaumont, Texas, the contractor responsible for procurement and driving of the piles, had some difficulty obtaining the pilings in the aftermath of the hurricanes“.

They were getting precast from a local provider, and a lot of the workers’ homes were destroyed,” Cochran says.

By mid-August, the contractor had completed pouring the concrete roof on the second of the three tanks, which Cochran describes as “almost a football field in diameter.” Each of the three tanks is actually 160,000 cu meters and is made up of concrete exteriors with an interior nickel tank. “The thickness varies from bottom to top like a typical tank, but the interior tank sheets are rolled offsite and shipped to site,” Cochran says.

At the same time Aker Kvaerner is building the concrete wall exterior of the tanks, the contractor is constructing a metal roof on the inside floor of the tank, Cochran says.

“On the last pour of the wall, you have an overlapping embed,” he adds. “When it’s all finished, you seal around the roof, use fans to blow air in and create pressure to float the roof up to the top of the tank and weld off the embed. Then you go on top of the metal roof and cap it off with concrete.”

This month, the contractor will be pouring the concrete pedestal/piers for the concrete roof of the first tank and performing steel and pipe work.

“The most unique part of this job, for me, is the marine, building the dock and doing the dredging,” says Cochran, who has built all sorts of refineries and tank systems worldwide but never worked on water. “Weeks Marine Inc. (of Cranford, N.J.) had a hydraulic dredger to cut the turning basin out of the dock for the carriers to come in. That dredger we had here was one of the biggest in the U.S.”

The dredge material was pumped offsite and used for beneficial use to restore wetlands. By mid-July, Weeks was driving pilings for the breasting and mooring docking, and preparing to set the unloading arms on the dock.

In December 2005 Cameron LNG submitted an application with the Federal Energy Regulatory Commission to expand the project. If the project is approved, another contract will be awarded, and the total processing capacity will be 2.65 bcf per day.

“We have received Federal Energy Regulatory Commission approval for the facility,” Larson says. “Some other approvals, however, are required.”