The U.S. Army Corps of Engineers is moving ahead with plans to clear munitions from the Maku'u Farm Lots.

The agricultural Puna subdivision, now leased by the state Department of Hawaiian Home Lands, was built over a 640-acre bombing range. During World War II, it was known as the Popoki Target Area.

"The site was reportedly used by the Navy as a target practice area during World War II," the corps said in response to an inquiry. "No records document this but ground reconnaissance revealed deteriorating air-to-ground practice bombs onsite."

The Navy acquired the land through a sublease. That lease was canceled Nov. 1, 1945, and the land was returned to the Territory of Hawai'i.

In 1990, the corps conducted a preliminary investigation and found 12 practice bombs within the subdivision, one of which contained a spotting charge.

A second site visit in 1991 found no evidence of ordnance because of the dense vegetation, but it was given a high priority for further action.

The corps in mid-2005 then conducted a much more thorough survey of the 640 acres, and identified two areas of concern: a 93-acre bombing target area and a 15-acre troop maneuver area.

In the bombing target area, the investigation collected 271 pounds of munitions debris. A search of the maneuver area found a hand grenade with its fuse missing and a trash pit containing shell casings of various sizes, up to .50-caliber.

Another follow-up search in July 2008 that focused on the two areas found no explosives or hazardous metal compounds.

"Archival records show no evidence for the potential of chemical warfare material or byproducts," the corps said.

The corps decided in August 2008 on what it called "the most ambitious" of the alternatives considered: the removal and disposal of all munitions-related items from the surface and down 2 feet. The 93-acre bombing target area and the 15-acre maneuver area will both be cleared of vegetation as necessary to allow the use of munitions detectors. Personnel will sweep the ground in lanes 5 feet wide.

Also, the corps will begin a public education campaign, which will include periodic public safety awareness meetings and the distribution of educational media to landowners and local businesses.

"In the public safety materials, the corps will stress that munitions encountered by the public should never be touched or handled by teaching the 'Three R Rule,' " an official said.

That is, recognize you may have seen ammunition, retreat and report it to authorities.

The corps issued a $1.56 million contract to Environet Inc. on Sept. 22 to remove the munitions and potential explosives.