A “leachable toxic” waste, as defined in the B.C. Hazardous Waste Regulation (HWR), is a waste that produces an extract with a lead concentration greater than 5 mg/L, when subjected to the regulatory extraction procedure US EPA Method 1311, also known as the Toxicity Characteristic Leaching Procedure (TCLP). A lead-containing waste that analytically proves to be a “leachable toxic waste” is characterized as a regulated hazardous waste. Paints made before 1950 contained large amounts of lead, as well as other metals, primarily as pigments. In fact, some paint made in the 1940s contained up to 50% lead by dry weight. If a building or structure was constructed before 1960, it was likely painted with lead-based paint. Since the 1950s, the use of lead has been more common in exterior paint than interior paint. Lead has also been used in water lines and plumbing including pipes, pipe or plumbing fittings, fixtures, solder and flux. Lead is also a common additive in plumbing materials such as lead solder, brass, bronze and other alloys. According to the document titled “Hazardous Materials in Construction1 ” (Levelton, 2013), lead paint was phased out of architectural paints from mid 1970s.
Before beginning a demolition project, a work plan should be developed. The work plan should include an assessment of the presence of lead-based paint on building/structure surfaces and components. The presence of lead should be confirmed on the basis of analytical test results from representative samples or other reliable field-testing methods.
Sampling should be carried out by a qualified person to ensure the representativeness of the samples in terms of the number and size of the samples, as well as sampling locations. All representative samples must be collected and handled in a way that preserves the original physical form and chemical composition of the sample, and prevents contamination in the field, in transit and in the laboratory. Generally, a representative sample means a sample which can be expected to accurately exhibit the average properties of the whole waste. In a demolition project, it is expected that different components of the whole waste could contain varying amounts of lead-based paints. Representative sampling of each of these components is needed in order to determine the average properties of the whole waste.
Recommended sampling locations include:
- Fences and porches
- Sidings, walls, doors, ceilings and window sills
- Stairs and banisters
- Painted built-ins (e.g., bookcases, shelves etc.)
- Paint and solvent wastes abandoned in the building prior to and during occupancy
Such wastes could include wood, metal, plastic, concrete, asphalt and any other material, and if hazardous waste, would most likely exhibit the “leachable toxic” characteristic.