Where does the North Shore flood debris go?

A pile of debris from a recent storm on Oahu’s North Shore — big enough to fill a soccer field with 9-foot-tall trash — is likely headed for the island’s near-capacity landfill.

Honolulu officials hope to divert as much of the estimated 6,000 tons of debris from the Waimanalo Gulch Landfill as possible. That facility is nearing capacity and is scheduled to close by 2028, and several city authorities are struggling to find a suitable replacement.

The main alternative to landfill is to burn debris with H-Power. The incinerator breaks down waste and produces less than 10% of Oahu’s electricity. The resulting ash will still be sent to a landfill, but it will take up less space and weigh less. However, if the trash is dirty or damp, it will be less flammable.

“This causes the components to turn to ash instead of burning, ruining the H-Power boiler when you try to burn it,” said Environmental Services Director Roger Babcock.

Today, Patsy T. Mink Central Oahu Regional Park in Waipahu serves as a giant outdoor drying platform to evaporate floodwaters.

Babcock said an estimated 80 percent of the flood debris, or 20,000 cubic yards (equivalent to one month’s worth of Honolulu’s municipal waste), will likely end up in landfills.

He said that while the stress from the disaster will definitely take a toll on the facility, it will not have a significant impact on the facility’s operations or expected lifespan. Approximately 225,000 tons of waste is sent to landfill each year.

“The amount is increasing every day, but it’s manageable. We’re trying to reduce the amount we send to the landfill, and we’re trying to get all the metal out. We don’t want to bury the metal,” Babcock said. “But we need to spread the word and get contractors to test it.”

One of the only safety valves is the landfill operated by PVT Land Company. The company has a county contract to pick up commercial building and demolition waste. Those materials will be sent there once people start rebuilding, Babcock said, a process that will take months.

The roar of heavy equipment enveloped the fenced-in area of ​​the regional park Monday as contractors sorted and consolidated piles of saturated bedding, window frames, twisted metal, stud material, vegetation and appliances.

Black construction cloth could be seen flapping against the temporary security fence as backhoe loaders picked up the remains of the farms and homes of people severely affected by flash flooding in Waialua on March 19 and 20.

“There was stuff crinkling up the house and the fence,” Waialua resident Brandon Rice said. He helped remove the debris using his own heavy equipment. “There were Tupperware containers, plastic tote bags, sheet metal from roofs and fences, washers and dryers that had washed down onto the road.”

Waipahu’s transfer area is effectively a super-large outdoor recycling center where city contractors separate debris. The city Department of Facilities Maintenance’s Otake Camp and Longbridge temporary collection sites were closed earlier this week, but residents were still able to bring debris to regular collection centers.

City crews will return to Waialua on Monday to conduct curbside trash collection, and residents are asked to separate damaged appliances from other debris and call (808) 768-3201 to schedule hazardous materials collection.

Residents had little time to organize

Local residents spent the weekend after the storm clearing away wet debris, and much of the work has already been done. They piled up debris at a temporary dump in Waialua before city workers arrived in droves.

It was difficult to distinguish the objects from each other, Rice said. The residents’ best option was to “grab everything and load it into a trailer.”

“Everything was muddy, crumbled and wrinkled,” he said.

This has allowed us to clear out the kitchen, garage, and driveway faster, but it complicates the handling of large amounts of debris in temporary storage areas.

Frequently, truck loads arriving at Patsy Mink Park are inspected for flammable and hazardous materials by contract workers at temporary dump sites.

“The contractors were pretty good at identifying propane tanks and electronics with their machines. I saw them take out batteries, propane and gas tanks,” Rice said.

Babcock said the amount of flood debris being trucked to transfer sites will soon level off.

“We actually expect the piles to start shrinking” as material is repurposed, he said.

Nearly 100 truckloads had been delivered as of Saturday, according to a county press release. Now, the county’s two contractors, DRC Emergency Services and Tetra Tech, must decide where everything goes.

“Some of it could be recycled, some of it could go to the landfill, some of it could go to H-Power,” Babcock said.

The county’s H-Power municipal incinerator turns an average of 2,000 tons of waste into ash a day, taking up 90 percent less physical volume in a landfill and 75 percent less weight, “and that space is at a premium,” Babcock said.

H-Power struggles with muddy, wet waste

The county’s ability to turn waterlogged debris into ash is limited by the H-Power incinerator’s high-volume combustion technology, which does not effectively burn wet or soil-contaminated materials.

Babcock said diesel fuel could be added to help burn the material, but efficiency would be significantly reduced.

That means more flood debris will have to be reclaimed than usual.

Some products recovered from trash, such as steel and home appliances, can be recycled.

Babcock said they will be processed by county contractors and eventually transported to the mainland in containers. For large appliances, “the contractor takes the chemicals, shreds it up, and compacts it just like a junk car,” he said.

This is no different from current recycling workflows.

Babcock said it was too early to estimate the final cost of removing the debris, but he was sure it would be “in the millions of dollars.” He said the county hopes to recover most of that money from insurance and the Federal Emergency Management Agency, but it’s difficult to predict the timing of federal compensation.

more: Governor asks Fed to fund flood relief

Babcock said Honolulu will retain one of the two companies, Louisiana-based DRC Emergency Services, to provide emergency services and debris removal on short notice.

Although the North Shore flooding was devastating and will take years to recover, Babcock said the cleanup effort is smaller than what the county is planning. In the event of a major disaster, such as a Category 4 hurricane, the company has the capacity to perform hundreds of millions of dollars worth of debris removal work.

Meanwhile, Rice said he expects another phase of debris removal will be needed as repairs to the home unearth large amounts of vinyl flooring, wood planks, sheetrock, insulation and fixtures.

“It’s all in the mud underneath, and as people move through the mud, there’s definitely going to be more trash and debris,” he said.

Civil Beat reporter Caitlin Thompson contributed to this article Climate change and environmental reporting is supported by the Healey Foundation, the Marisula Fund of the Hawaii Community Foundation, and the Frost Family Foundation.