The University of Hawai'i's two submersible craft will descend 900 to 2,000 feet to the ocean floor five miles south of Pearl Harbor starting next week to search for tons of chemical weapons that were dumped during and after World War II, the Army said.

The 15 days of daytime dives, augmented by the use of robotic vehicles at night, are part of the Army's ongoing assessment of the health and environmental effects from the old munitions, which were ditched by the military at three deep-water sites five to 10 miles south of Pearl Harbor and Wai'anae.

The submersibles Pisces IV and Pisces V will conduct 12 dives beginning Monday.

UH researchers will take water and sediment samples to see if there are metals from the munitions or any residue of chemical agents, as well as visually observe the effects of more than 60 years on the containers.

In nearshore waters off Wai'anae, meanwhile, conventional weapons ranging from 30-caliber rounds to grenades and large-caliber artillery projectiles were dumped in a spot nicknamed "Ordnance Reef."

Tad Davis, the Army's assistant secretary for the environment, yesterday said sampling of water, sediment, fish and limu will be coordinated by UH at Ordnance Reef in April and again in late August or early September.

In late fall, the Army also plans to test the use of robotic underwater vehicles and water-drill technology for the removal of some of the shallow-water munitions.

A 2006 National Oceanic and Atmospheric Administration study of military munitions dumped in the Poka'i Bay area off Wai'anae concluded the waters, fish and general area were safe.

But Davis yesterday said the 2006 study was done "to very quickly take a look at the conditions in the Ordnance Reef area," and it was decided that a more detailed study needed to be done.

"Everything we looked at to date indicates to us that there's probably negligible impact, but there's still enough of a concern ... that we want to be as thorough as we can," Davis said.

William Aila Jr., a Wai'anae Coast resident who has been active in seeking a cleanup, said the community seems satisfied with the timetable.

"Of course we'd always like it to be done yesterday, but it's a reasonable timetable given the permitting process and the pieces of the project that they have to get in place," Aila said.

A 2007 report to Congress said 2,558 tons of chemical agents were dumped at three deepwater sites off O'ahu, including lewisite, mustard, cyanogen chloride and cyanide.

Included in the ordnance dump were 15,000 M70 115-pound mustard bombs, 1,100 M79 1,000-pound cyanogen chloride bombs and 20 M79 1,000-pound cyanide rounds. The weapons are in waters up to 10,000 feet deep.

The Army said it is spending $4.75 million to investigate the removal of the near-shore munitions, and $2.3 million for the deep-water investigation.