Moanalua Valley resident Lisa Hall smiled after she watched a helicopter lift tons of boulder fragments — more than 30 bags — from a hillside behind her home yesterday.

"It was a relief," Hall said. "Now we can sleep in our bedroom tonight."

Yesterday morning's airlift concluded a $309,000 U.S. Army Corps of Engineers project to remove five boulders above a handful of homes on Ala Mahina Street. One of the boulders was perched precariously on a slope behind the home Hall rents, and since she moved there this year, she has worried that it would tumble down.

"It was a big concern because the geologist had mentioned that that one big boulder could have come down and landed in my home any day," she said.

The contractor, Prometheus Construction, began the project Aug. 14 and finished the job ahead of the contract's October deadline. Removing the boulders involved putting fencing over the rock faces and breaking the boulders into pieces. The boulder fragments were put in 35 to 40 heavy-duty bags, which Pacific Helicopters lifted from the hillside to Tripler Army Medical Center grounds, where they will be trucked away.

Residents in a few area homes were evacuated during the airlift, which took about 40 minutes, Tillotson said.

Prometheus Construction vice president Cliff Tillotson estimated the largest boulder — about the size of a small truck — weighed more than 15 tons, with the others about 3 tons. The Army Corps of Engineers has said the boulders were just inside Tripler Army Medical Center's property, on a hillside about 260 feet above street level.

The project was initiated by concerns from Moanalua Valley residents and an inquiry from U.S. Sen. Daniel K. Inouye's office in February, the Army Corps of Engineers has said.

"The whole hillside has been swept really thoroughly now," Tillotson said.

Prometheus also completed a $1.4 million Army Corps of Engineers rockfall-mitigation project in Moanalua Valley two years ago. That project followed heavy rains and landslides that damaged properties near Tripler in late 2003.

State Rep. Glenn Wakai, D-31st (Moanalua Valley, Moanalua, Salt Lake), said he and Inouye have been working to secure $6.5 million to remove boulders on the Red Hill side of Moanalua Valley. He said the Navy has identified 49 sites there as having dangerous boulders.

Reach Lynda Arakawa at larakawa@honoluluadvertiser.com.