TCLP (Toxicity Characteristic Leaching Procedure) testing helps determine the mobility of both organic and inorganic analytes present in liquid, solid, and multi-matrix wastes. If you have a hazardous waste producing facility, the state of Florida requires you to conduct testing for all waste materials. Similarly, discharge testing is also a requirement for companies that discharge waste water. These requirements are further enforced by governing bodies such as Environmental Protection Agency (EPA) or the Department of Environmental Protection (DEP).
How Does TCLP Testing Work?
The TCLP testing procedure is an analytical method to stimulate leaching through landfill. If a load or pike of waste is subjected to ambient environment (biological and weather decay), what would be the leach out of that waste? What would be the concentration? And what would be the potential effect of the environment? TCLP testing answers all of these questions.
The procedure involves using a mildly acidic pH, acetic acid solution as the extraction fluid. As it is the predominant acid generated from biological decay processes, acetic acid is preferred for use. The waste sample is leached for up to 18 hours. The consequent slurry is then filtered, and the aqueous filtrate is considered the TCLP extract. Due to the mildness of the extraction fluid, TCLP have final pHs ranging from 5.0 to 6.0. Later, the extract is analyzed for different analyte groups. Individual contaminant concentrations are also compared to the maximum allowable TCLP concentrations.
Types of Solid Wastes
A solid waste is considered toxic if it contains significant levels of toxic contaminants. The contaminants are include but are not limited to:
- Dioxins—Vinyl Chloride and Trichlorophenol
- Heavy Metals—Cadmium, Lead,Arsenic, Mercury, Barium, Selenium, and Chromium, Silver
- Pesticides—Methoxychlor,Endrin, Toxaphene, Silvex,Lindane and more.
- Volatile Organic Compounds (VOCs)—Carbon Tetrachloride,Benzene, MEK, etc.
Waste generating facilities must determine whether or not their waste exhibits any characteristics of toxic waste. The facility may either be test the waste using the approved TCLP methods or apply the knowledge of the waste in reference to the raw materials and production processes used.
If you are positive that your waste doesn’t contain any toxic contaminants, you are not required to test it. However, waste producers must use TCLP testing if they are unsure or if the raw materials produce by products are toxic in nature.
A typical TCLP testing procedure usually has 6 steps:
- Separate the liquid and solid portions of the waste
- Crush the solid waste portion
- Next, place the crushed solid waste that simulates the conditions of a landfill by filtering the solid waste through it
- Collect any leachate you can from the system
- Blend the separated liquid portion of the waste (if any) with the leachate
- Analyze the leachate for constituents that raise concerns over toxicity
When Is It Not Needed?
As TCLP testing an analysis is time consuming, it is important to know that there are three conditions where the presence of toxic contaminants does not automatically require testing:
- If a total analysis of waste, not the extract shows that the individual contaminants are not present in the waste or not present in the levels that could exceed the regulatory threshold then you don’t need to conduct TCLP testing.
- If the waste is 99.5% liquid then the waste itself can be used an extract for analysis, extensive TCLP testing is not required.
- If the waste is 100% solid, the maximum theoretical leachate concentration is 1/20 of the total concentration. If the value is below the regulatory threshold, TCLP testing may not be conducted.
When Is It Needed?
Assuming that the regulatory levels of toxicity for lead is 5 ppm, here are the three examples when TCLP testing would be necessary:
- If a semisolid sludge contains 5 ppm ore more total lead, then it would be considered a D008 waste. If there was a lower concentration, it would not be D008.
- If dry ash or solid bricks contain less than 100 ppm dissolved lead, the extract could not possibly have more than 5 ppm, and the solid could not be a D008.
- If wastewater solutions contain 5ppm of dissolved lead then it would be a D008 waste. A lower concentration would not require testing.
If a solid brick or dry ash contains 100 ppm or higher concentration of elemental lead then it is possible that the extract produced by the TCLP could have 5 ppm lead. Therefore, a TCLP testing must be performed.