When many engineering consultants develop bid specifications for soil remediation projects, there are often two categories for soil disposal pricing: "Hazardous" and "Non-Hazardous." However, the issue is more complicated than that, particularly when solvents are involved. Very often it is more appropriate to have four or five pricing categories, especially if waste characterization has not yet been performed.
One of the most common misconceptions becomes apparent when we are asked questions like "at what concentration of TCE is the soil hazardous?" There is the assumption that there will be a hazardous and non-hazardous segregated piles, based on he levels detected in the laboratory.
However, there are hundreds of hazardous waste codes under RCRA, and only the 40 or so compounds on the D-List, or characteristic wastes are determined to be hazardous based on concentration, and even then it is based on the level found in the leachate after a TCLP test is performed. However, most waste codes are considered "listed" rather than "characteristic" wastes. These include waste codes that begin with F, K, U or P. Generally speaking, these wastes are regulated based on the source of generation and mere presence of one or more compounds.
For example, F001 through F005 codes represent spent solvents that have been used in a process such as degreasing. It does not matter how many ppm are present. K-wastes are clearly regulated because of the process by which they were generated, regardless of whether any chemical or compound is present. A U-code denotes what is generally referred to as a virgin, or unused, chemical. Soil or other media contaminated by spills or leaks of virgin chemicals also carry the U-code. However, sometimes a compound on the U-list is present in a product, but which is not the only active ingredient, may not have a hazardous code at all. A genuinely unknown source of contamination, such as those cases where a surprise hit of PCE or chloroform appears in a soil boring during a Phase II, that waste may be classified as non-hazardous.
To further complicate issues, disposal options transcend the possible classifications. Most regulated solvents appear on the EPA’s list of chemicals restricted from land disposal, the Land Disposal Restrictions (LDR’s) or Land-Banned compounds. There are universal treatment standards (40 CFR 268.43) for each compound. If the concentration (totals) exceed this level, the soil must be treated to below that standard prior to land disposal, usually at a cost of three times that of soil that meets the standards for direct landfill disposal. Then, the soil must pass a treatability study at the disposal facility, or it may require incineration, of course at an even higher cost.
Back to the common question so often posed. If there is any TCE in the soil, and it is a spent solvent or a virgin spill, your (of your client’s) waste is hazardous. Whether or not it meets treatment standards does not affect its classification, but it does dictate what disposal methods and costs are available. Since it is the source and mere presence of the TCE that makes the soil hazarous, you must find non-detectable levels for your "non-hazardous" pile. But, then, if it is non-detectable, you do not need to remediate that soil anyway, so you probably will not have a non-hazardous pile.
The above is presented as guidance only. Of course, the responsibility to classify waste is the generator’s, and you should check with the EPA and your state agency’s waste classification division.