Earlier this week I had the opportunity to visit the TDS landfill and recycling center in Buda, TX. The trip was part of my Sustainable Materials class at the University of Texas at Austin. The class is taught by Professor Raissa Ferron of the Civil, Architectural and Environmental Engineering department and focuses on reducing the environmental impacts of construction materials while still meeting the needs of a growing society in an economically sustainable way.
Despite our arriving more than an hour late after an accidental detour through downtown Buda, our young tour guide, Jason, whose normal work day should have come to a close before we even arrived, greeted us with a smile and the type of enthusiasm for sustainability that leaves you feeling like you can go home and single handedly reduce global carbon emissions to zero. As Jason drove me and my classmates between the mountains of rubbish I couldn’t help but wonder how many people stopped to think, even for a second, where their garbage would end up. I didn’t know until our visit to the landfill that every piece of garbage I threw away was being trucked to Buda, Texas before it was compacted to one third its original size and covered with soil by nightfall.
Photo of TDS Landfill. Credit: Alliance Innovation
Texas Disposal Services (check them out at http://www.texasdisposal.com/) handles waste from Austin, San Antonio, San Marcos, Georgetown, and surrounding communities throughout 35 counties, and I’d come to learn throughout our tour that they do it with some of the most advanced, sustainable methods in the world. They pride themselves in their extremely small working face (the part of the landfill that isn’t covered by earth), their ability to efficiently recycle almost any kind of plastic, an incredible composting program (all food scraps from the University of Texas’s food services are composted here), and their clean grounds and happy neighbors (we saw very little trash other than what was in the working face, and the property was surrounded by nets to catch any stray trash). My personal favorite advancement was the resale store where the landfill makes a second round of profits (the first comes from the dumping fee) off of hidden treasures TDS employees handpick out of the rubble. They also have a game preserve with over 2,000 animals and 100 different species including rhinos, giraffes, and tigers.
Throughout our drive Jason continually stated his frustrations about the inefficiencies with which construction and demolition waste is disposed of. As a structural engineering student, and with most of my background in the construction industry, I paid extra attention to what he had to say about C&D. The problem is most materials in a building are attached to or embedded in other materials (think rebar in concrete, shingles nailed to the roof, or paint on a wooden deck) and they often show up at the junk yard that way. If it’s not profitable for the owners of a disposal company to separate the materials themselves for recycling or use as a fuel, the materials end up in the landfill. We can save huge amounts of energy by recycling everyday materials (according to a Popular Mechanics article, making aluminum cans from recycled aluminum reduces energy consumption by about 96% when compared to using virgin materials ), so I started to wonder, what are the energy implications of sending so many C&D materials to the landfill rather than back to the supply chain? And how can we do better?
Residential and commercial buildings are responsible for approximately 40% of the energy consumed in the United States . A study at the University of California, Berkley estimated that construction and demolition waste makes up nearly 40% of the total waste stream in a country. Concrete makes up roughly half of C&D waste, of which about 25% is recycled (in reality, it’s downcycled and used in concrete footings or as road base material). The Berkley study concludes that if we could up that number to 50% we could reduce the life-cycle greenhouse gas emissions of our buildings by 2-3%. That’s the GHG equivalent of removing about half a million cars from our roads- and that’s just concrete. There is even more energy saving potential from reusing building components rather than recycling the materials .
While Jason and his crew are doing a great job of figuring out new ways to deconstruct buildings at the end-of-life stage, what if we thought more about deconstruction during building design? If we put just a little bit of thought during the design phase into making a building easier to disassemble, TDS’s job would be a lot easier when it’s time to dispose of building materials. The trouble is the market gives little incentive for planning ahead to the deconstruction of a building. While energy reductions for building operation lead to direct financial savings, there’s no money to be saved for an owner who pushes for a design that plans for disassembly.
In some countries, regulations are implemented that make designing for efficient disposal of certain products profitable. For example, driven primarily by lack of space for landfilling, Germany enacted an Extended Producer Responsibility (EPR) law that requires manufacturers to take responsibility for their own packaging waste. They can choose to either pick up packaging directly from consumers, or pay a government run organization to pick up the packaging .
Buildings present unique challenges for EPR and other such market tools. As I mentioned earlier, buildings are complex systems made up of largely composite components. Not only that, but there are often hundreds of manufactures that make the various components of a building. Reverse logistics becomes a serious nightmare in EPR for buildings- getting the materials back to their producer can more than offset any environmental benefits. Additionally, buildings’ relatively long lifespan has several environmental implications. For example, if a designer does design for deconstruction, and recycling technologies change significantly over the building’s life, the designer’s intent might not be realized because of evolved recycling technologies . There’s also just a different mindset for buildings. People are starting to realize that packaging can be designed to be disposed of, but buildings are supposed to last, not be disassembled.
Despite all of these challenges, I’m on board with Jason and his crew at TDS that we can do a much better job of diverting C&D waste back into the supply chain. Maybe it will take some landfill engineers getting in the same room as design engineers, or maybe to be qualified to design a building you should first have to spend some time working at a landfill. Regardless, the possibility for energy savings is huge, not to mention the material resource and land use benefits of diverting from the landfill.
|||EIA, “Annual Energy Review,” EIA, Washington, D.C., 2010.|
|||P. Santos Vieira and A. Horvath, “Assessing the End-of-Life Impacts of Buildings,” Environmental Science and Technology, pp. 4663-4669, 2008.|
|||A. A. Guggemos and A. Horvath, “Strategies of Extended Producer Responsibility,” Journal of Infrastructure Systems, pp. 65-74, 2003.|