The year 2005 presented considerable challenges for mixed C&D recyclers in many parts of the country, as regulatory and environmental issues provoked questions within a couple of different end markets.
Speaking to attendees of the C&D World Conference, which took place in Miami in mid-January, University of Florida researcher Tim Townsend reviewed controversies that have surrounded the handling of both treated scrap wood and gypsum drywall.
In the case of drywall, the creation of malodorous (and potentially toxic) hydrogen sulfide (H2S) gas in ground-up drywall has caused complaints from some users of alternative daily landfill cover (ADC) made from mixed C&D debris and of remediated soil (RSM) used to make berms and embankments.
The problem can be genuine and hard to deny when the rotten-egg odor begins to make its presence known, says Townsend.
He indicated, though, that the addition of certain materials might serve to stave off the creation of H2S within ADC. Such materials can include concrete fines and lime, according to Townsend.
Additionally, the Construction Materials Recycling Association (CMRA) is working with the University of Florida to develop best management practices in the handling and sorting of mixed C&D materials to reduce the potential for H2S problems.
Mixed C&D recyclers have also been striving to keep wood treated with chromated copper arsenate (CCA) out of their end products for several years, as the arsenic contained in CCA is undesirable both in boiler fuel shipments and in mulch.
But the widespread damage caused by Gulf Coast region hurricanes is only serving to bring more treated wood into the stream in the South at a time when processors do not have the time or labor power to sort carefully.
Again, Townsend and the CMRA are devising best management practices with the intention of giving recyclers guidelines to continue to produce fuel and mulch products well below acceptable limits for arsenic.
The C&D World Exhibition & Conference took place Jan. 15-17 in Miami. It is the official show of the Construction Materials Recycling Association and is managed by GIE Media Inc., publisher of Construction & Demolition Recycling magazine.