Painting an LBP picture: crushing and recycling concrete that contains lead-based paint may pose few real hazards

Construction & Demolition Recycling, March-April, 2004 by Stephen Cosper

A recent study by the U.S. Army Corps of Engineers suggests that the lead content in construction and demolition (C&D) concrete to be crushed and recycled is well below safe limits set by the U.S. Environmental Protection Agency (EPA). These promising results could make the C&D industry more comfortable with recycling concrete that contains lead-based paint (LBP), preventing such paint-coated concrete from going to a landfill.

The past few years have seen a growing national trend to reduce C&D waste by reusing or recycling wood, concrete and other materials. The U.S. EPA estimates that about 20 percent of the debris and scrap from C&D sites in the U.S. is being reclaimed.

Besides lingering perceptions that recycling is not cost-effective, one of the main deterrents to widespread recycling efforts has been the presence of LBP on many of the materials. And with good reason: Depending on the end use of recycled LBP--containing products and the associated potential for leaching lead, contractors could be held liable under the Resource Conservation and Recovery Act (RCRA).

U.S. ARMY EFFORTS

The Corps's Engineer Research and Development Center, Construction Engineering Research Laboratory (CERL), is conducting multiple studies that seek to expand deconstruction and reuse of Army buildings. The Army owns some 1 billion square feet of real property, much of which has been deemed obsolete. More than 39 million square feet of World-War-II-era buildings have yet to be removed.

Under the Residential Communities Initiative, 70,000 old units are being demolished. Contemporary barracks complexes will replace hundreds of Korean-War-era barracks and associated buildings. In total, the projects will generate 26 million tons of demolition debris in the next 15 years. Some Army installations report that C&D debris constitutes 80 percent of their solid waste stream, of which about 63 percent is estimated to be concrete.

On-post landfills art typically available to contractors for "free" disposal. However, installations report their costs in expanding, operating, maintaining, monitoring and eventually closing the landfills to be roughly $50 per ton. The cost of hauling and tipping debris to an off-post landfill can be much higher. This cost is likely to increase as C&D landfills across the U.S. close.

A typical WWII-era barracks building generates more than 110 tons of debris (about 150 cubic yards) when demolished. The economic and environmental burdens associated with landfilling debris are significant. Installations will not be able to meet Department of Defense directives to divert 40 percent of their overall solid waste streams without reducing C&D landfilled waste.

While not common practice, some installations have succeeded by using deconstruction. Since 1992, 140 WWII-era buildings have been deconstructed at Fort McCoy, Wis., saving roughly $3.5 million. Fort Knox, Ky., has removed 285 buildings in the past three years, generating more than $250,000 in income (through recycling) and saving roughly $640,000 in demolition costs. Two production buildings at Twin Cities Army Ammunition Plant in Minnesota totaling 925,000 square feet were deconstructed in 1995. Roughly 2.3 million board feet of timbers were salvaged, saving more than $400,000 in demolition costs.

CERL's research helps installations to make the best decisions about building disposal options. The effort began with field demonstrations of deconstruction at Fort Campbell, Ky., and Fort Ord, Calif., and has expanded to include removal of LBP from salvaged materials; applications of mechanized equipment to deconstruction; recycling concrete from buildings; identifying environmental performance of recycled concrete materials containing LBP; and modeling the cost, material values and schedule impacts of salvaging materials for reuse and recycling.

CONCRETE TEST AT FORT ORD

Military installations have recurring needs for aggregate to use as fill, roads, revetments and other projects. Obtaining this material for local use from buildings demolished on site has several advantages, including waste diversion and transportation cost savings. In the past, most contractors who recycled concrete largely ignored the possibility of lead contamination. However, more recently some have sampled for LBP presence, raising concerns about RCRA and discouraging concrete recycling in some minds.

CERL conducted a study at Fort Ord to learn if LBP in crushed concrete actually poses a hazard. The Corps, the Construction Materials Recycling Association and the National Association of Demolition Contractors jointly funded the study. The project involved demolition of 300 old family housing units. These buildings were pre-cast concrete on concrete foundations. Driveways and streets were also demolished.

Prior to demolition, CERL sampled at the site for laboratory tests, including: air-ambient, air-personnel (OSHA), soil, dust, building structure and pavements. Concrete was separated from the C&D materials stream and transported to another site for processing with an Eagle two-stage impact crusher. Researchers took several test samples from the aggregate pile and from under the conveyors.