Start To Finish

In Chicago, Allied Waste Services recently opened an $8-million construction and demolition (C&D) debris recycling facility, which aims to provide needed recycling services to area contractors as well as produce marketable end products.

"This facility exemplifies Allied’s commitment and leadership as the region’s largest recycler by offering communities and businesses economically sustainable recycling options," says Bob Kalebich, general manager of MRFs and transfer stations for Allied, which provides collection, recycling and disposal services to customers in the residential, commercial and industrial sectors throughout the United States.

When designing the system, provided by Machinex Industries Inc. of Quebec, Allied carefully considered incoming material and available end markets, Kalebich says. "We took a combined approach," he adds.

In 2005, the city approved amendments to its Construction or Demolition Site Waste Recycling Ordinance, which increased recycling targets to 25 percent initially. Targets were later increased to 50 percent in 2007. "We needed to help our customers manage the new Chicago ordinance on C&D," Kalebich says. In downtown Chicago, he explains, contractors must deal with tight footprints on many of their job sites, which makes source separating a challenge. "A lot of the big builders were having issues because they have a hard enough time keeping one roll-off container on the site. Now everyone is telling them you need separate boxes for wood, OCC, metal and garbage."

The Chicago facility started as a transfer station and relied heavily on manual labor to sort the comingled loads. "It wasn’t always cost-efficient," says Kalebich.

The new sort system is designed specifically to accept comingled loads, employing both mechanical and manual sorting in the process.

The system, which has the capacity to process up to 1,500 tons of material per day, starts with a Vecoplan LLC shredder that shreds material to a 22-inch minus size. From there, the material proceeds to a pre-sort station, where OCC, large metal and any bigger items are removed.

The primary screen that follows reduces that material to 2-3/8-inches or less. "Fine pieces of wood, a lot of the gypsum and drywall dust goes through there," says Kalebich. The material then goes across a light fraction separation system that uses air jets to further sort material. "This helps us get a better sort of the material downstream," according to Kalebich. "It takes the dust particles out and the smaller wood."

The remaining wood and heavy materials, such as brick, concrete and metals, go onto the water bath separation system. "At that point, the heavies sink to the bottom to a stainless steel conveyor. It goes across a magnet to take out metals, and we’re left with the brick, concrete and block," explains Kalebich.

Wood from the float tank is pushed to a conveyor where contaminated wood is sorted out. The remaining clean wood is ground to make a wood fuel product.

While focusing on meeting its contracting customers’ needs, Allied also had end markets in mind with the design of its Chicago sort system. The recycling center is a key source of chipped wood that will be used to fire boilers at Robbins Community Power Plant. The plant needs 350,000 tons of wood chips per year.

"Robbins was looking to redevelop the plant in the south suburbs. They used to be a waste-to-energy facility and were going to burn straight wood," according to Kalebich. "They came to us as one of the largest haulers in the market place here and asked us how much wood we have available in Chicago, and in the suburban market as well. We didn’t know the answer, and that’s what led us down the path of the C&D facility."

Allied conducted a waste audit to see how much wood and other marketable C&D material was in the loads being collected from construction sites to determine what kind of system would best suit its needs.

In addition to providing wood chips to Robbins Community Power Plant, Allied is targeting markets for other materials as well. The company is in talks with U.S. Gypsum to take recycled gypsum and has also had companies express interest in recycled shingles for use as road base. Allied has also located a compost facility as a potential end market for the fines material that the system generates. "We’re looking to develop more markets," Kalebich says. "Our ultimate goal is to minimize what goes into the landfill."

Kalebich credits the green building movement as a key factor driving the increase in C&D recycling. "I believe the value of green building and interest in it is growing. Everybody’s trying to develop and build green buildings, and they are still looking at the financial impact of construction and demolition recycling."

More than half of the waste generated in the Chicago area is C&D debris—the largest component of the city’s waste stream, according to information provided by Allied. In addition to the new recycling targets provided by Chicago’s C&D recycling ordinance, the city’s contractors are seeing growing demand from their customers to use green building techniques.

"As LEED certification from the U.S. Green Building Council becomes more and more a standard in new construction, builders and developers can rely on a successful C&D recycling program to gain two out of 13 points awarded by the USGBC in the Materials and Resources category," adds Kalebich. "The growing demand for building green requires a convenient, easy and cost-competitive service for C&D recycling. By accepting mixed, unsorted debris in one centralized container, Allied Waste provides by far the most desirable solution for recycling C&D."

Kalebich says Allied makes education a priority and offers assurance that the material that comes into the C&D facility is in fact recycled. "That was one of the biggest things—we needed to open it up as an educational facility and encourage people to come through," he says. "The main focus is to show people—this is what we’re doing, your material is being recycled. The C&D industry just happens to be one of the stages for the LEED program. It’s worth points to demonstrate that you’re doing recycling."

The author is managing editor of C&DR and can be reached at jgubeno@gie.net.