A yellow "excavator" machine the size of a mastodon picked out hunks of metal for recycling and separated them from the wood, concrete and other building debris that will end up in O'ahu's only landfill dedicated solely for construction waste.

The sight of workers sorting recyclable building material from acres of trash will be played out with increasing regularity in the coming years as Hawai'i's construction industry heads into a boom that hasn't been seen since the 1980s.

The handful of demolition and recycling companies such as Island Demo Inc. hope to see a jump in work and revenue, especially $10 billion worth of military home construction planned on O'ahu over the next 50 years.

But the amount of construction debris that will be generated, how much will end up at the private, PVT Land Co. landfill in Nanakuli, and what portion can be recycled have yet to be determined, raising questions about the future of tons of old building materials.

A 1995 study of construction rubbish conducted by the state Department of Health found that O'ahu generates 600,000 tons of construction and demolition material per year.

"We don't know if the amount has gone up," said John Valera, environmental planner with the health department. "We're still trying to put our arms around the whole thing. We don't have any forecasts with respect to the upcoming construction boom."

Room for next 20 years

The 600-acre PVT landfill still has plenty of capacity for the next 20 years to take in exclusively construction-related debris, said Albert Shigemura, president of the PVT Land Co.

The landfill's future is separate from the current debate raging across O'ahu over where to build the next landfill to handle regular household trash and other, non-construction-related rubbish.

But Valera of the health department is still sensitive to the issue of generating any unnecessary construction waste. "It is a concern," he said. "Finding landfills is a very hot potato that nobody wants to touch."

Most of the answers will come from the two primary contractors that have won three separate contracts to build and renovate portions of 15,000 Army, Navy, Marine Corps, Air Force and Coast Guard homes on O'ahu and manage them for 50 years.

Within the next few months, the companies hope to have a better idea how much debris the work will generate.

"I don't have an estimate of tonnage or cubic yardage," said Thad Bond, senior vice president of Hawaii Military Communities, LLC, which has been named to build the first phase of 7,300 Navy and Marine homes. "But we're going to try and recycle as much as we can on site. The less we can put in the landfill, the better it will be for everybody."

Within the next month, Hawaii Military Communities plans to hire a demolition company that most likely will be from Hawai'i, Bond said. The demolition company will help determine how much concrete, wood and other materials can be reused.

Much will depend on how many of the homes contain asbestos, lead-based paint and treated lumber. Environmental reports on the Navy homes show some evidence of asbestos, which can be removed, but also lead-based paint, which can't.

"With lead-based paint, you have limited opportunities to recycle," Bond said. "If you put it through a crusher, then the lead becomes airborne. So if you can't crush it, then you can't reuse it on site."

Philosophical change

Bond's comments represent the kind of philosophical change that Hawai'i's construction industry has gone through since the last building boom.

Construction companies now have a greater appreciation for the limits and costs — they're called "tipping fees" — associated with O'ahu's landfills, said Gail Suzuki-Jones, energy analyst for the state Department of Business Economic Development and Tourism.

"Experienced contractors have gotten on the bandwagon and now understand the environmental and economic benefits of recycling," Suzuki-Jones said.

She also likes much of the preliminary planning so far from the primary military contractors.

"It sounds like they have a lot in the works," Suzuki-Jones said. "They have a system for recycling their concrete aggregate material. They have a plan to inventory all of the trees on base and assess the condition and whether or not they'll reuse them, keep them in place or move some of the landscape material."

John Leary, owner and CEO of Island Demo, is certain his company can recycle 90 percent of the debris from the upcoming construction boom — as long as it doesn't involve asbestos, treated lumber or lead-based paint.

His company donates usable items — such as stainless steel kitchen counters and old appliances — it retrieves from old buildings. And it grinds up concrete from old buildings to be immediately reused on the new construction site.

"We absolutely look for every way we can to recycle," Leary said.

Piony Omoso, Island Demo's operations manager, watched the other day as workers picked through the remnants of the Cartier store.

The company runs 24 hours a day, seven days a week, tearing down buildings and sorting the reusable from the rubbish.

It's a dirty, sweaty job. And as Omoso watched the work in front of him, his thoughts briefly drifted to potentially busier days ahead.

"Yeah," Omoso said, "that could be good for all of us."