O'Hare Recycles Old Roofing Shingles into New Runway Pavement

Author: 
Thomas J. Smith
Published in: 
November-December
2014

More than 6,000 old roofs are now part of the airfield at Chicago O'Hare International Airport (ORD).

As part of its on-going O'Hare Modernization Program, the airport is incorporating recycled asphalt roofing shingles into the sub-layers of its recently constructed Runway 10R-28L and taxiways K and L. The project makes ORD the first U.S. airport to be certified by the FAA to use recycled roof shingles in its asphalt.

The Chicago Department of Aviation now plans to use the recycled-content material for all future runway and taxiway projects at both O'Hare and Midway International Airport.

When preparations began in 2003 for the $8 billion ORD re-build, re-using old roofing shingles was not

factsfigures
Project: New Runway, with Recycled Content in Asphalt
Location: Chicago O'Hare Int'l Airport
Runway: 10R-28L
Engineer: O'Hare Runway Designers, LLC
Lead Firm: Epstein
General Contractors: Turner-Acura-Lindahl Tri-Venture
Paving Contractor: Plote Construction
Total Project Cost: $500 million
Paving, Lighting & Signage Portion: $82 million
Estimated Commissioning: Oct. 2015
Project: New Taxiways, with Recycled Content in Asphalt
Taxiways: K & L
Engineer: Epstein
General Contractors: Joint venture of Walsh & Terrell
Paving Contractor: K-Five
Total Project Cost: $47.5 million
Paving Portion: $18 million
Estimated Completion: Oct. 2015
Of Note: Pavement bid specifications required the use of recycled roof shingles in the warm-mix asphalt for sub-layers; first project certified by the FAA to use the environmentally conscious asphalt blend

part of the plan. But cost savings and the opportunity to reduce the use of virgin oil earned the practice a spot on the airport's airfield agenda.

"In Chicago, it is now expected that we will go the extra mile and pioneer these efforts in environmental sustainability," notes Rosemarie Andolino, commissioner of the Chicago Department of Aviation. "Our contractors and team members are constantly looking for new initiatives and evaluating them to see how we can bring them to the airport market."

Roads to Runways

Although the state of Illinois has been using recycled asphalt shingles in its road and highway pavement for several years, the concept is new to the airport industry. ORD eased into the new practice by using the environmentally conscious asphalt in roadway, shoulder and apron paving projects. The Chicago Department of Aviation then worked with its engineers, contractors and the University of Illinois to obtain the necessary modification of standards from the FAA to permit the use of the material into asphalt mixes for runways and taxiways.

"When you make a change to something that has always been that way for years, you want to ensure it meets all the safety requirements," Andolino explains, noting the heavy stress that fast-moving aircraft place on airfield pavement.

The product used at ORD is categorized as a "warm-mix" asphalt, because it is produced and applied at lower temperatures - and consequently requires less fuel and produces lower plant emissions - than traditional hot-mix products. Warm-mix asphalt is also considered to be safer for crews to handle, and stretches the paving season, because it can be applied in cooler weather. 

"In the field of environmental issues, the trust we have built over the last 10 years with the FAA is there," says Andolino. "They know we will not move forward with something that jeopardizes safety, and they know we want to be aggressive to ensure that we are creating the most environmentally sustainable airport."

Financial & Performance Implications

The use of asphalt with recycled material reduces the need for liquid asphalt by 2% to 3%. Project officials estimate that using it will save ORD $1.65 per ton on the Runway 10R-28L and taxiway projects, for a total of $665,000.

About 7,000 tons of recycled shingles will be part of the 287,888 tons of asphalt that will be applied in the sub-layers of the 7,500-foot runway. Another 2,500 tons of the material will be part of the 105,000 tons of asphalt going into the base layers of the two taxiways. According to project participants, it takes about 100 residential roofs to produce 150 tons of the finished recycled material.

ORD's new runway and taxiways are scheduled to be operational next October.

The primary contractor for Runway 10R-28L is Turner-Acura-Lindahl Tri-Venture; Plote Construction is the paving contractor.

While the overall runway project is estimated to cost $500 million, the tab for paving, lighting and signage is expected to be $82 million. Walsh and Terrell formed a joint venture for the $47.5 million taxiway project and K-Five is the paving contractor.

Applying the warm-mix asphalt with recycled roofing shingles is no different than applying a traditional mixture, reports Rocco Danna, K-Five's manager for the taxiway project.

Plote's research and development manager, Greg Rohlf Sr., notes that his firm has been using recycled asphalt in its mixes for seven years with very good results. In addition to containing asphalt, the shingles also contain cotton or fiberglass fibers. Pavement with recycled shingles is "better and more durable" than pavement made solely of "virgin" materials, because of the extra fibers, Rohlf explains. 

Prior to the runway project at ORD, Plote tested the material by repaving portions of I-90 with a mix containing recycled shingles and comparing it to a portion of I-55 repaved with a traditional mix. Test results showed that the shingle product was "as good or better than the virgin product," Rohlf reports. This allowed the state to set specifications that encourage more recycling and save taxpayers money, he adds.

The formula each paving contractor uses for its mix is tied to the certified recycled materials obtained from processor(s), Rohlf explains. Plote tests samples of its warm-mix asphalt every day, he adds.

Before its current project, the company had paved many other runways and taxiways at ORD. Rohlf estimates that Plote now uses asphalt with recycled shingles in about 70% of its projects.

K-Five had previously completed five runway and taxiway projects as part of ORD's modernization program. It now incorporates the recycled material in 99% of its current projects, Danna reports.

Flatwork Pioneer

When the O'Hare Modernization Program was in the planning stage, project leaders turned to U.S. Green Building Council standards; but the Leadership in Energy and Environmental Design guidelines only cover buildings and facilities, not flatwork like ORD's large airfield initiative. This prompted ORD to create its own industry-specific guide for sustainable design and construction, which it now makes available to other airports. 

Managing the movement of dirt has been a key factor during the construction of Runway 10R-28L and other airfield projects. (Throughout the long-term modernization program, ORD will build four new runways, extend two others and add several miles of associated taxiways.)

The goal is to move dirt once or create stockpiles for future use, notes Andolino. So far during the modernization program, airport contractors have moved 28 million cubic yards of soil - enough to fill Chicago's iconic Willis Tower (formerly known as the Sears Tower) 12 times. Following ORD's Balanced Earthwork Plan, crews have avoided 700,000 truck haul trips and helped save more than $150 million by handling dirt in a more strategic and environmentally responsible manner. The new practices have also decreased overall construction time and enabled a massive stormwater detention basin to open a year ahead of schedule, she adds.

"By keeping all that dirt work onsite, we have been able to reduce the number of trucks that traverse the neighborhoods around the airport," Andolino elaborates. "This helps the people with less aggravations (and) fewer roadway repairs; it helps the planet, because we are reducing carbon dioxide emissions and reducing landfill dumping; and it helps us profit, because going green can actually save money."

The airport has saved another $5 million via the on-site recycling of old pavement and building materials into re-useable aggregate for asphalt and concrete pavement.

ORD's bidding specifications require contractors to use ultra-low sulfur diesel fuel and construction equipment that meets Tier 2 emissions standards. Contrary to some predictions, the requirements did not increase project costs and were "the right thing to do," notes Andolino.

Other Green Projects

With a variety of environmental projects already up and running, ORD anticipates using geothermal technology to heat and cool its new south control tower. It also continues to explore the use of solar energy, especially as the technology improves. 

In November, Chicago again hosted Airports Going Green, an annual conference that presents the best practices in airport sustainability. Andolino describes the international event as a "think tank of ideas."

"We are always keeping our eyes and ears open, watching what is happening in road construction, rail construction or at other airports," she relates. "We are going to keep evaluating opportunities and the options with new technologies and procedures."

ORD's existing green projects run the gamut - from a mandatory recycling program for concessionaires and charging stations for electric vehicles to on-airport beehives and weed-munching goats. 

Turning Shingles into Blacktop

In the Chicago area, a network of companies is helping breathe new life into residential renovation debris by recycling asphalt roofing shingles into materials paving contractors can incorporate into their asphalt mixes. To further encourage the re-use of "tear-off" shingles, Illinois now bans the disposal of old shingles in a landfill if there is a certified recycler nearby.

In most cases, it is cheaper to take a dumpster of old shingles to a recycling center than to a landfill, says Brian Lansu, vice president of US RAS Association-Midwest, a trade group that promotes the use of the old shingles.

EPA-certified recycling centers sort and clean shingles removed by roofing contractors so the materials contain only 1.5% debris. Processors then clean the shingles further, so only 0.5% debris remains. Next, processors use a two-step process to grind the materials into a granular form, with pieces no larger than 3/8-inch to meet Illinois highway standards.

According to Lansu, the recycled material is sold to paving contractors for about $40 to $50 per ton; and using recycled roofing shingles reduces the amount of new asphalt cement - oil - needed for asphalt mix by about 5%. Depending upon the price of oil, contractors could pay $500 to $800 a ton for "virgin" oil product, he adds.

Lansu cautions paving contractors to adjust the grade of oil in their formulas to keep mixtures flexible. Recycled materials will make asphalt "stiffer" without such adjustment, he explains.

Contractors that recently paved Runway 10R-28L and associated taxiways at O'Hare International Airport used materials from Southwind RAS and Falcon Green Resources. (C&D of Wisconsin is another processor that serves the Chicago area.)

Currently, demand for recycled materials outstrips the supply produced by the three processors; but more recycling centers are opening in untapped areas of the state to fill the gap, reports Lansu.

Subcategory: 
Runway/Ramp

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