Excavator sits near a pile of drywall

August 19, 2013 | 6:00 a.m. CDT
An excavator sits near a pile of drywall and lumber Thursday at the City of Columbia Sanitary Landfill. The city uses the building materials to add carbon to the mix balancing out the nitrogen provided by the organic waste.

RELATED STORIES: New truck will let city expand its commercial composting