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

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.

The buildings, foundations and streets were all crushed together to make road base. CERL sampled from the finished recycled aggregate product.

PROMISING RESULTS

Samples from the intact buildings showed an average of 3,700 mg/kg (milligrams to kilograms) lead concentration in the paint. This is typical for LBP-coated concrete and lower than what is normally found for LBP on wood surfaces.

The crushed aggregate from the processed piles at the crusher site had lead concentrations averaging 17 mg/kg. This level is quite low, given the intended application as a road base. The U.S. EPA limit for total lead concentrations in soil in residential areas is 400 mg/kg. CERL further tested the two highest concentration samples using the Toxicity Characteristic Leachate Potential (TCLP). The results were less than 0.01 mg/ kg--far below RCRA's limit of five.

The area around the crusher were sampled after a day of processing the concrete. The average total lead concentration in fines under the conveyor belts was 111 mg/kg. This level is well below the limit for lead in soil; however, the fine nature of this residue makes it prudent for workers to wear protective masks when working around this equipment. CERL again performed TCLP for lead on the two samples with highest total concentrations (160 and 130 mg/kg). As with the crushed product, the result was less than 0.01 mg/kg.

Samples from clean concrete pavement showed a total lead concentration of less than 1.0 mg/kg. CERL also took samples from the demolished streets and driveways and found 1.5 and 17 mg/kg lead, respectively. The higher concentration in the driveway could be because of leaded gasoline exposure through the years.

WHAT'S NEXT?

This study provides an important first step in determining if concrete with LBP is safe to recycle. For the buildings tested and the recycling processes used, the findings show no hazard exists as defined in the regulations.

With concrete comprising such a high percentage of C&D mass and with a recycling rate that can be improved, there is huge potential to reduce the amount of C&D generated material that is landfilled. In the Army alone, concrete generated from planned demolitions in the next 15 years will exceed 16 million tons. CERL's continuing research will result in guidance for the industry to maximize opportunities in the recycling and reuse of these materials.

PERMISSION TO CRUSH

Concrete and asphalt recyclers can have hurdles beyond lead-based paint (LBP) to clear in order to run a successful crushing and recycling operation.

As NADC past president Leonard Cherry noted in his remarks at the C&D World Exhibition & Conference in January (see page 59), zoning and permitting issues in states such as Texas and California are making it difficult to locate crushing and pavement plants.

Some within the recycling industry have accused landfill owners of lobbying to convince legislators and regulators to target crushing plants for extra (negative) attention as a means of directing more concrete to landfills. In other cases, adjacent property owners fearing potential noise and dust from a crushing operation have opposed plant sitings.

In Elgin, Ill., a proposed C&D recycling plant that would handle asphalt pavement and shingles has been opposed by the neighboring city of Bartlett because of fears of noise, dust and increased truck traffic.

Nearby in Des Plaines, Ill., the owner of a mobile home park is opposed to a proposed asphalt plant and is alleging in a lawsuit that the city permitted the plant without holding an open meeting for public comments. The owner of the proposed asphalt plant is building the new facility to replace another that was lost to an O'Hare International Airport expansion project.

The San Jose, Calif., City Council had to overrule the city's planning commission to allow the Graniterock company to put asphalt recycling equipment next to its existing asphalt mixing plant.

In a battle of words and legal maneuverings that does not appear to be over (additional permits still need to be secured), Graniterock officials have noted that the opposition is coming from owners of homes that were built in the 1980s, long after the company was established.

On the Web: HOME BASE

Some findings of the U.S. Army Corps of Engineers' Research and Development Center can be reviewed at the ERDC Web site at www.erdc.usace.ermy.mil.

The author is an environmental engineer with CERL and can be contacted at [phone] or by e-mail at [e-mail].