ST. GEORGE — The Federal Aviation Administration issued Monday a final Record of Decision that paves the way for construction to begin on a long-awaited replacement airport for St. George.

"This will be the highest-cost, public improvement project that St. George has ever undertaken," St. George Mayor Dan McArthur said during a news conference held in the City Council chambers. "When we first started this, we figured it would cost about $100 million. The cost estimate now will probably be at least 50 percent higher."

An environmental impact statement, completed earlier this year, added $4.5 million to the project's overall cost, said Mike La Pier, St. George airport manager.

The EIS, which was court-ordered following a lawsuit filed by the Grand Canyon Trust, included a comprehensive noise analysis from all sources — data that was missing from the environmental assessment, he noted. Calls to the trust were not returned Monday.

"There has been more study done on this airport than the Chicago O'Hare modernization plan," LaPier said. "This report is exhaustive, and the reality is that it addresses all the questions and concerns that were raised."

City officials said they should have a new cost analysis and financial plan for the replacement airport completed by the end of the week. After that, a design team will be selected from a qualified bid process, and officials will need to acquire nearly 1,000 acres around the proposed airport site.

The replacement airport site is located about five miles southeast of St. George. Unlike the current airport, which is landlocked on top of a mesa in the middle of the city, the replacement airport site will provide precision landing on a runway long enough to accommodate regional jet service.

SkyWest Airlines is currently limited to flying 30-passenger turboprop aircraft out of the St. George airport. The new airport would accommodate larger, quieter jets that carry up to 100 passengers.

"This has been ongoing for almost 20 years," City Manager Gary Esplin said. "We've been thinking about this project and figuring out what to do with the existing airport for a long time. It's going to be a challenge, but we'll hopefully get it done within the next few years."

The replacement airport site includes an abandoned Civil Aeronautics airstrip once used by local remote-controlled aircraft clubs for weekend events. Unsanctioned uses on the paved runways included late night drag races, which police routinely shut down until the area was fenced off.

City officials pledged Monday to clean up the area and work with the FAA to secure more grants to purchase property and build the airport.