The ACC economist notes that about 60% of the new petchem capital expenditures in the U.S. are being made by offshore petchem owners. For example, Moore cites Chinese investment in new methanol production facilities on the Gulf and West coasts to supply China's growing fleet of methanol-to-olefins plants.

Just last month, Russian fertilizer giant EuroChem announced its intent to build a $1.5-billion ammonia and urea production and distribution complex on a 900-acre site in Louisiana's St. John the Baptist Parish—another center of energy and petchem activity.

"While a final investment decision remains subject to the EuroChem board's approval, finalizing the purchase agreement on the St. John the Baptist Parish property allows EuroChem to move forward with the planning and preconstruction phase of the project," says Jim Harris, a company spokesman.

"The timing on the start of construction and the start of operation of the plant is contingent upon final board approval and other preliminary work, including environmental permitting," Harris says.

Johannesburg-based Sasol is proceeding with an even bigger petchem investment: a nearly $9-billion ethane cracker and derivatives complex near Lake Charles that is expected to create more than 5,000 construction jobs and triple Sasol's chemical production capacity in the U.S. The facility will produce about 1.5 million tons of ethylene per year, and six new downstream plants will produce a range of high-value derivatives used for synthetic fibers, detergents, paints, film and packaging.

Sasol broke ground on the Lake Charles-area project in March; mechanical, electrical and instrumentation work at the site is expected to occur mostly in 2016 and 2017; and the complex itself is expected to be finished in 2018. Fluor Technip Integrated, a joint venture of Fluor Corp. and Technip, is serving as the project's primary engineering- procurement-construction management contractor, and Sasol in February selected five Louisiana-based contractors to undertake key elements of the project.

U.S.-based petchem firms are also very much in the mix. For example, Chevron Phillips Chemical, a joint venture of Chevron and Phillips 66, within the next few weeks will complete a 220-million-pound-per-year normal alpha olefins expansion project at its Cedar Bayou facility in Bay City, Texas. The firm also is nearing the halfway mark on $6 billion in ethane-cracker and polyethylene projects at Cedar Bayou and Old Ocean, Texas, that will be finished in mid-2017.

Sarah Blodgett, spokeswoman for Dow Chemical, says her company "remains on track" on several related construction projects at its Freeport, Texas, petchem complex. A propane dehydration plant that will make propane-based polyethylene "is now more than 90% complete, with startup in mid-2015," she says.

A much bigger Dow project—a 1.5-million-ton-per-year ethane cracker, also at Freeport—"has 90% of engineering and 15% of construction completed at this stage," says Blodgett. That job, which will employ up to 2,000 construction workers, is on time, on budget and expected to come on line in 2017.

PCL Industrial's Free says he "wouldn't be surprised" if a heightened level of petchem construction activity in the U.S. "continued for eight to 10 years." Even when the building boom eventually slows down, he says, the facilities being built now will require maintenance, occasional upgrades and further expansions.

Petchem owners often prefer that the contractors who build their projects continue on in maintenance roles, given their familiarity with the facilities and their expertise, which should profile additional work opportunities well into the 2020s, Free says.