Marine scientists with side-scan sonar, a robot submersible and divers will head out to Poka'i Bay today to survey World War II-era munitions dumped in relatively shallow waters off the Wai'anae Coast.

William Aila Jr., who works, fishes and scuba-dives in that area, has a pretty good idea of what they'll find.

"I can tell you what I've seen for myself. I've seen 4- or 5-inch shells. I've seen ammunition pallets ... I've seen grenades," said Aila, who works as the Wai'anae harbormaster and is a Democratic candidate for governor. "I've seen circular objects that resemble munitions that are partially sticking out of the sand. I'm not an EOD (explosive ordnance disposal) expert, but if it looks like a bomb, it probably is a bomb."

Hundreds of grenades are scattered in a 300-by-300 foot area, Aila said, noting he has been told torpedoes and drums also lie on the ocean floor in that area.

Separating fact from fiction is partly what the 30-member team will be doing over the next two weeks.

At the request of the Defense Department, the National Oceanic and Atmospheric Administration — assisted by the Hawai'i Department of Land and Natural Resources and University of Hawai'i — also will collect water, fish and sediment samples at the site, known as Ordnance Reef, and compare the results to sites without munitions.

UNBIASED ANALYSIS

An area of 5 square nautical miles in waters ranging in depth from about 18 feet to 300 feet will be surveyed.

Michael Overfield, a NOAA marine archaeologist and principal investigator for the project, said an unbiased analysis is planned.

"We're saying, 'We don't know anything,' so let's get the best technology to tell us everything that's out there," Overfield said. "There's a lot of speculation of, 'Well, we hear there's this size bomb ... and this kind of weapon.' Let's find out."

A final report is expected in the fall, and could lead to recovery efforts.

There are no suspected chemical weapons in the area targeted for the survey, officials said.

Publicity about the U.S. military's practice of dumping chemical and conventional weapons at sea decades ago led to data last year that 4,220 tons of hydrogen cyanide were dumped somewhere off Pearl Harbor in 1944. During that year, the military also dumped 16,000 100-pound mustard bombs "about five miles off of O'ahu."

In 1945, off Wai'anae, the Army dumped thousands of hydrogen cyanide bombs, cyanogen chloride bombs, mustard bombs and lewisite containers. NOAA charts identified some as being in 1,600 feet of water.

An Army Corps of Engineers survey in 2002 at Ordnance Reef identified more than 2,000 military munitions at depths ranging from 15 feet to 240 feet, with the majority observed deeper than 60 feet.

U.S. Rep. Ed Case, D-Hawai'i, yesterday said the first step is to quantify munitions in the deep-water and shallow-water sites.

"In terms of any shallow-water munitions, we clearly have to dispose of it," Case said. "We have to take it out or render it nondangerous."

REPORT PLANNED

A report on deep-water munitions sites in U.S. waters is due out in late June or early July. Case said there needs to be some "practical judgments" about whether deep-water nonchemical weapons pose a threat, but "chemical (weapons), I think that's a different story, and I'm not sure what the scientists will say the answer is in on chemical (weapons in) deep water."

The ecology examined during the two-week survey will be compared to a separate control area. NOAA said there have been no reports of tainted seafood.

Gov. Linda Lingle, who yesterday received a pierside briefing from NOAA at Aloha Tower Marketplace, along with Case and U.S. Rep. Neil Abercrombie, D-Hawai'i, said residents on the Wai'anae Coast are understandably concerned about what's in the ocean, and the mapping will help provide answers and determine what action to take, according to a spokesman.

For the two-week shallow-water investigation, the 40-foot vessel Manacat will crisscross waters near Poka'i Bay using Global Positioning System navigation and side-scan sonar that also provides depth information for an almost 3-D image, Overfield said.

CAMERAS AND DIVERS

A 3-foot remotely operated vehicle with a video camera will be used to examine suspected ordnance, and divers also will be available down to a maximum of 120 feet. Explosive ordnance disposal personnel will be on board to help identify munitions.

A 50-foot UH research vessel will operate in deeper water, where sensing equipment will be winched down on heavy duty cable.

Scientists also will be collecting munitions samples to see what effect salinity has on the corrosion of steel.

A Wai'anae sewage outflow pipe affects nutrient levels in the vicinity, and a comparison will be made to marine samples taken elsewhere.

Aila, the harbormaster, said he was disappointed a magnetometer is not being used in the survey, but Overfield said "remnant magnetism" locked into rapidly cooled volcanic rock can skew results. Most of the area is hard-bottomed, which should make identification easier, Overfield said.

Divers routinely come across unexploded munitions in Poka'i Bay, and Aila said the grenades he spotted were in an area favored by spearfishermen seeking octopus and squid.

Reach William Cole at wcole@honoluluadvertiser.com.