A Portland engineering firm has merged with Stantec Inc., a large Edmonton, Alberta-based engineering and architectural design company.

Stantec acquired Industry and Energy Associates in a private sale on July 2, bringing the company’s holdings to five firms in Maine: two in Portland and one each in Scarborough, Topsham and Limestone. All of these acquisitions have been made since 2006.

The high cost of running a small business was becoming too great a challenge, said Ken Rogers, the IEA president who will now manage the office’s operations.

“To keep the company successful and to give our employees a good place to grow and get good benefits, merging with Stantec was the best decision,” he said.

IEA already has plans to work on a natural gas project in Venezuela and a solar project in New Mexico. Last year it brought in about $12 million in revenue.

In 2007, IEA completed a project on Galapagos Island in Ecuador involving the installation of three wind turbines and solar power that was partially funded by the United Nations Development Program.

None of IEA’s roughly 50 employees will be laid off as a result of the sale, said Rogers, however the three Stantec offices in the area will most likely move to one location in Scarborough in the future.

IEA’s experience in green engineering was a major deciding factor in the purchase, said Alison Smith, a Stantec spokesman.

The Topsham office has led the environmental permitting for nearly every wind farm in Maine, including the ones at Stetson, Record Hill, Rollins and Oakfield.

Stantec engineers in Portland also designed the “warm-mix” asphalt at Logan International Airport in Boston, which requires less energy to produce and emits fewer emissions.

Stantec employs roughly 9,300 people and operates more than 150 locations in the U.S. and Canada.