CERL finds lead levels negligible.

Results of a study of crushed concrete that included slabs of material coated with lead-based paint indicate the traces of lead are well below dangerous levels.

Attendees of the C&D World Exposition & Conference in New Orleans in late January were the first to hear the encouraging results, presented by Steve Cosper of the U.S. Army Construction Engineering Research Lab (CERL).

Cosper and CERL conducted the study on concrete debris generated at the demolition site of the Fort Ord complex in California. The Construction Materials Recycling Association (CMRA) and the National Association of Demolition Contractors (NADC) funded the study.

Although Cosper is still finalizing the full draft of his report, he offered show attendees a preview.

Noting that 400 parts per million (ppm) is the EPA limit for material to not be considered a hazardous waste, Cosper said that only paint chips tested alone surpassed this limit at 3,500 ppm following TCLP (toxicity characteristic leaching procedure) testing methods.

Otherwise, concrete fines generated by crushers on the site tested at 110 ppm; crushed concrete tested at 17 ppm; and soil located near the crushing plants tested at 30 to 60 ppm.

Air quality tests revealed that equipment operators working in the area were unlikely to encounter hazards.

Cosper noted that the crushing contractor did a good job controlling dust, but that at 110 ppm, enough lead is in the fines stream to "merit careful handling."

He said aggregates from a mixed stream of bare and painted concrete should be suitable for road base and other desired end markets.