Hawaii’s PVT Land Co. is recovering C&D debris from its landfill and from contractors using a forward-thinking approach that includes sophisticated equipment, techniques and technology.
Every landfill has a lifespan. And in localities with limited land, strategizing that space makes sense—from economics to geography. This couldn’t be more true for the state of Hawaii, an isolated area of islands with only so much space, says Steve Joseph, vice president of operations and permitting at PVT Land Co., Nanakuli, Hawaii, on the island of Oahu.
“Our problem is we have limited land. If you think it’s hard on the mainland, it’s twice as hard over here,” Joseph says of maintaining the company’s landfill.
PVT Integrated Solid Waste Management Facility is Oahu’s only construction and demolition (C&D) landfill. In summer 2014, the company incorporated a new reclamation and recycling system for C&D debris.
Each day, trucks offload about 1,775 tons of C&D debris—mostly wood, metals, concrete and asphalt—at the 135-acre facility. Joseph says about half of the debris entering the facility is processed into feedstock, which will be used as fuel by a gasification facility being planned by Honua Power LLC, as well as H-Power and other power generators.
PVT’s recycling system can process 800 tons of feedstock per day from C&D debris. Honua will burn the feedstock to create synthetic gas while other yet-to-be-determined gasification and waste-to-energy facilities will use it in other applications, such as for jet fuel, Joseph notes.
Joseph says because Hawaii is so isolated, acquiring oil can be a “real drain on the economy, so anyway for us to produce power has additional benefits of producing jobs and keeping a circular economy.”
He continues, “For us as an island, if you don’t have oil and you’re having to buy it from somewhere else, every dollar you spend on oil leaves the economy.” Joseph adds that even if oil prices are low, having feedstock material created from C&D debris and other secondary materials supports the economy better than oil. “The price of oil will [always] go back up,” he notes.
Joseph says his job entails much planning for the future and that the idea to convert C&D debris into a renewable energy resource has been a goal of his and the company’s for more than a decade.
He explains how leaders at PVT have historically taken the “long view” in business decisions by looking ahead. “Everyone who sits on the board is in their 60s; we’re making plans that are beyond just us.”
Joseph says he gives a lot of credit to the PVT board for making such a large investment in recycling equipment “where the return is after you retire when things start to pay off.”
Lucky for PVT Land, the return on its investment can potentially come more quickly since it already has a large inventory of material sitting in its landfill. The company plans to dig up much of what it has buried in its landfill over the last two decades.
Joseph estimates about 4 million cubic yards of C&D debris buried in PVT’s landfill is recoverable.
Beginning this year, PVT plans to use excavators to reclaim, process and reuse or recycle up to 80 percent of that C&D material. “We’ll have a portable screener up there to screen it as soon as we dig it up, and we will retain the dirt because we will use that for cover in the future,” Joseph describes. These efforts are expected to stretch the life of the landfill out by 30 years.
Prior to PVT Land introducing its recycling system, Oahu contractors didn’t have many options for recycling, Joseph says. While some construction and demolition firms would recycle metals and wires from different projects, admittedly, “a lot of stuff got buried,” Joseph recalls.
Some of the material PVT has buried in its landfill that it plans to reclaim includes: a 40-foot ship, whole spools of wire and 18 floors of concrete from a shopping center destruction.
Much of what is recovered will be processed as feedstock for fuel applications. PVT currently has 1.5 million tons of feedstock buried on-site for reserve that is covered with dirt and sprayed with carbon dioxide to preserve it, Joseph says. The company has had to stockpile its feedstock as the planned gasification facility is still in its permitting phase.
However, this hasn’t prevented PVT Land from recycling internally. Joseph says the company has used crushed concrete to construct interior roads and serve as structural fill under its recycling center to build it up to standards. As fill is considered a “premium” or “hard to get” in Hawaii, Joseph says, using reclaimed crushed concrete to create a firm surface on the facility’s interior roads and as structural fill has proved to be advantageous for PVT.
“We don’t sell any crushed concrete out as we haven’t gotten to the point to do that. Sometime in the future we might have more than we need, but for now crushing runs all day, every day,” Joseph says.
“We’re forward thinking in that we do all of our own construction,” he adds.
Processing the pieces
When construction and demolition (C&D) debris enters the PVT Reclamation and Recycling System, it is processed through a series of steps as described below:
- Excavators load C&D debris into the feed conveyor, pulling out pieces of metal, concrete and wood that are too large to pass through the system.
- A vibrating screen (taper slot) allows debris less than 6 inches in size to fall through onto an “unders” conveyor while the rest continues to the “overs” conveyor.
- At the top of the unders conveyor, a magnetic separator pulls anything magnetic—hinges, nails, bolts and other metal pieces—from the conveyor and drops it into a metals bin.
- A secondary taper slot separates dirt, rocks, broken glass and other pieces of debris that are less than 1 inch in size, which are stockpiled and taken to the landfill.
- Strong blasts of air lift lighter pieces of C&D debris and allow heavy pieces to fall through to a conveyor that carries them to a waiting bin.
- On this sorting line, workers clean and separate materials, pulling pieces of rock, metal and other materials from the feedstock debris stream.
- Ferrous metal, aluminum, copper and wire are all pulled and dropped into assigned bins. The goal is to allow only C&D debris suitable as feedstock to continue on to the grinder.
- Feedstock debris drops onto the grinder feed conveyor. Before it reaches the grinder, it will pass beneath yet another magnetic separator that will pull any magnetic items that slipped through.
- On the overs sorting line, a team of 10 sorts debris 6 inches in size and over, pulling metals and other materials from the debris. These materials are dropped into bins below for further recycling.
- C&D debris suitable for feedstock is ground and shredded into pieces of uniform size and stockpiled for pickup
Forward thinking also comes into play with regard to how PVT plans to recover the buried C&D debris. The company has placed GPS equipment on its Caterpillar 836 compactor and other machines to identify where the C&D debris is buried in the landfill as opposed to the cell containing pure waste, such as asbestos and truck tire beads that contain rubber and metal.
“Everything we never wanted to dig up again all ended up in one location, and we can recycle everything else,” Joseph explains. “As we got into this further and further we made the conscious decision to keep anything we don’t want to dig up in one location.”
He continues, “For anything we might want to go back and get, we GPS those in so we can go back and dig them up.”
While things at PVT seem fairly large today, the company did indeed start out small. “We had a much smaller system,” Joseph observes. Over time, PVT slowly incorporated pieces to increase what the company was capable of accomplishing.
About 15 years ago, PVT workers started recycling metals, which led to recycling concrete, “and then we stepped it up from there,” Joseph states. The company added at first a short pick line with a trommel screen to pull principally metals out, he says. “That was a good learning experience on how to put the system together,” he says of the company’s trial-and-error tactics.
Joseph says PVT also worked closely with engineers from San Diego-based CP Group, which designed and installed the company’s recycling system. “Because we negatively pick, we just have to take out the things that are not feedstock; we only have to handle 20 to 30 percent of the material to have a finished product, and that was our advantage of working with our engineers in California at CP Group: how best to design the system for our purposes,” Joseph says.
While he says PVT has had much support with the addition of its recycling and reclamation system, from a state senator to the island’s construction industry as a whole, convincing the regulatory community of the modification has proved challenging.
“The challenge is a combination of changing the way people think about it and view it,” Joseph says. Getting regulators who are so used to disposal to rethink the benefits of recycling and what comes out of it involves “changing the mindset of everybody,” he says.
Joseph explains, “By recycling, even though it might be more expensive than disposal, in some areas in reality it’s not because you increase the economy by moving the material around. You have to look at the overall benefits you get out of it.” That situation could not be more true when you are on an island, he emphasizes.
Many people embrace recycling, but others have a hard time accepting the change from a strictly disposal mentality, Joseph suggests. To help educate the community, PVT puts on numerous tours for schools and any other interested groups to let them see the daily operations for themselves.
While the process of education the community has taken a while, Joseph says, “I think people really recognize the benefits we bring to the community and the entire island with what we do.”
Leading the way
As all of its customers are in the construction industry, Joseph says PVT looks for ways to benefit them most. For starters, costs to dispose at PVT’s site are half that of the city and county landfill, according to Joseph.
For companies that request it, PVT tracks the percentage of debris that is brought to the facility and recycled. By supporting the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) certification program, PVT supports the construction industry, i.e., its customers, Joseph says.
While PVT’s landfill space is limited, so, too, are the job sites where contractors work on the islands. Most construction and demolition projects in Hawaii don’t have enough room on-site to include collection bins for separating materials, Joseph says. PVT charges an extra $2 to $3 per ton to track what materials the company recycled, which Joseph says is cheaper than having a company employee watch to ensure the correct materials are placed in the proper bin.
“If they go in and fill up a bin, they can throw everything in it, we will sort it for them and tell them how much stuff got recycled on a monthly or project basis. We offer them LEED tracking and tell them where all the stuff went to,” Joseph says.
Some contractors have decided that it is easier and cheaper to send materials to PVT for LEED tracking even if it isn’t a LEED-certified project, just to see what they are recycling, Joseph notes.
PVT works with a LEED consultant with to ensure the company is up to date on changing LEED rules. “We want to make sure we’re giving accurate reports out to our customers for LEED. If something didn’t qualify and now it does, we want to make sure we let our customers know,” Joseph explains.
He adds, “We work closely with our customers who are in the construction industry and this is one of the ways we figured we could support them. There’s just not enough room at sites here.”
The author is associate editor of Construction & Demolition Recycling and can be reached at firstname.lastname@example.org.