Sunday, April 22, 2012

Published in the Sun March 25, 2012

Mining Oil from the Dump

Like many who thought they had their careers planned, the recession put Josh Broussard onto a different path.  He had started his professional life as a chemical engineer smocked up in a semiconductor clean room, but now his office is a trailer on the edge of a landfill.  In spite of the humble (and odiferous) surroundings, Josh loves his new job.  He gets to work on two environmental questions at once:  What do we do with all the trash?  And how can we use petroleum products more effectively?

Here is Josh’s challenge.  Every year, ten million tons of composition shingles are ripped off American roofs and thrown into landfills.  Shingles contain about 20% asphalt, which is the sticky residue left over after the gasoline, diesel, and other oils are taken out of the crude oil.  Each ton of shingles contains the equivalent of one barrel of oil; twice as much oil as can be extracted from a ton of Alberta tar sands.  Not only is discarding used shingles a waste of oil, but it is also exceptionally wasteful of expensive landfill space because shingles do not compact well, leaving a lot of airspace in the pile.

Josh works for WM Asphalt Products, a special division of Waste Management, the company that runs the Williamson County landfill.  His job is to divert composition shingles out of the waste stream, and recycle them into a product that can be used to pave and repair asphalt roads.  It’s like he is drilling for oil, but he’s doing it in the dump.

When a roofing contractor replaces a damaged composition roof, he has to get rid of the old shingles.  He can take them to Josh, even if they are mixed with nails, flashing, and other roof debris.  Josh will charge him $32 a ton, up to a maximum of $64, to recycle the shingles.  This is less than the contractor would be charged to dump them in the landfill, so the contractor comes out ahead.  Josh and his helper Tim Cunningham then “clean” the shingles, which means they pick out all the wood, plastic soda bottles, and other extraneous trash.  The shingles are then run through a giant grinder and chopped into pieces no bigger than one half inch.

The chopped shingles can be sold for $25 to $35 a ton as an additive for hot mix asphalt which is used for paving roads.  Hot mix asphalt can be up to 5% recycled shingles by weight.  The asphalt in shingles is actually harder than the rest of the mix, so it helps prevent heavy wheels causing deep ruts in the road.  Even better, the recycled shingles reduce the need for virgin asphalt, which costs $500 a ton.  The Texas Department of Transportation states that using 5% recycled shingles in hot mix to pave one mile of a two lane highway uses 80 tons of shingles and saves 40 cubic yards of landfill space.  So the hot mix company saves money, the roofing contractor saves money, and both of them give money to Josh.  It’s a win/win/win situation.  Even the county comes out ahead by saving landfill space, which costs millions of dollars to build and operate.

Asphalt recycling is just part of a larger trend called Resource Recovery:  the economical harvesting of “trash” for valuable materials.



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