Tetra Tech Inc. on Wednesday said it reached a definitive agreement to purchase most of the assets of Proteus EPCM Engineers, an Australian engineering company that specializes in mining, for an undisclosed amount.

Proteus is based in Perth and focuses on projects involved in iron ore, precious and base metals, and aluminum extraction. It employs about 150 people mostly in Western Australia, and has annual revenue of about $30 million. Tetra Tech, based in Pasadena, said the transaction is expected to close early next month.

The deal is in line with recent acquisitions that Tetra Tech has made in Canada. “Like Canada, Australia’s high-growth economy is driven by strong demand for natural resources,” Chief Executive Dan Batrack said in a statement. “This acquisition will serve as a gateway to new markets across Asia and Africa.”

In a separate announcement, Tetra Tech said that Steve Burdick, who has been its

acting chief financial officer and treasurer since March, had been appointed to the job permanently. Brian Carter was appointed as vice president, corporate controller and chief accounting officer to fill Burdick’s previous position. Burdick replaced David King, who had taken a job in China.

In addition, Frank Gross, formerly president of the industrial/process business unit of URS Corp., was hired as executive vice president and president of the remediation and construction management segment. He succeeds Don Rogers, who has retired.

Shares were down 12 cents, or less than 1 percent, to $22.08 in midday trading on the Nasdaq.