Defining RCRA-Hazardous Waste

Q. As part of our manufacturing operation for a new product line, we recently installed a small tumbling and deburring operation. At the beginning of this project, we decided we would not discharge this wastewater to the sewer since it would be the only process wastewater to sewer, and after meeting with the city, we did not want to go through the hassles of applying for and maintaining compliance with a new wastewater discharge permit for such a small flow. Also, we expected this wastewater would be non-hazardous. We currently generate less than 100 gpd and store the wastewater in totes. After we generated some wastewater, we agitated the tote with a portable mixer, took several samples, composited them together and had them analyzed for metals, pH, oil and grease.We then sent this analysis to two waste disposal companies for quotes. One company said since our waste stream had a lead concentration of 40 mg/liter and this is over the TCLP threshold of five mg/liter, it is a RCRA-hazardous waste and gave us a quote from transportation and disposal as such. The other company claimed they can handle it as a non-hazardous waste since the waste stream’s concentration is less than 19 times the TCLP threshold of five mg/liter. Obviously, disposal as a hazardous waste is much more expensive than non-hazardous waste. Can you help us decide which way to go? Both companies insist they are right. K.F.

A. Not only is there the cost issue but more importantly, the liability issue. It is your responsibility as the generator to properly characterize your wastes and assume the financial responsibility if they are disposed of improperly.

Our assumption is that you analyzed your tumbling/deburring wastewater for total metals. Furthermore, this type of wastewater typically contains a large amount of solids. Lastly, using your knowledge of the process as well as the metal parts being processed, narrowing your focus on the hazardous waste characteristic of Toxicity Characteristic Leaching Procedure (TCLP) for metals seems to be reasonable and defensible.

The TCLP is described by USEPA Method 1311 (www.epa.gov/epaoswer/hazwaste/test/1_series.htm). For those liquid wastes containing less than 0.5% (5,000 ppm or mg/kg) dry solids, the liquid sample is passed through a 0.6–0.8 micron glass fiber filter. and the liquid that passes through the filter is defined as the TCLP extract upon which the analysis is to be performed. Since you did not provide any solids analysis, I assume it was not performed. Therefore, I recommend the waste stream be analyzed for total solids.

If your analytical lab discovers total solids are less than 0.5%, then have them perform the above filtration step and analyze for lead. If they find lead to be less than five mg/liter in this extract, the waste stream is RCRA non-hazardous. If they find lead to be greater than five mg/liter, the waste stream is RCRA hazardous with a RCRA waste code of D008.

If the liquid waste has a total solids content greater than 0.5%, the waste is still filtered as described above, BUT the liquid extract is held and the solids are mixed with 20 times its weight in extraction fluid. After solids extraction and filtration, the two liquid extracts are combined to form the TCLP extract upon which analysis is to be performed.

The bottom line is that the high concentration of lead in this waste stream makes you run the TCLP in order to make a definitive decision as to its RCRA hazardous waste characteristic.

If you find this waste is indeed RCRA hazardous, you have three options:

Find the source metal of the lead and evaluate if a change of basis metal is feasible so as to reduce lead so that it passes TCLP and the waste stream could be disposed as a non-haz ardous waste.
Re-evaluate discharging this waste stream to the sewer, although some form of pretreatment will likely be needed unless your city has very generous lead limits given your very small volume.
Become a hazardous waste generator. If you generate more than 2,200 lbs (or about 260 gallons) per month, you become a large quantity hazardous waste generator with numerous requirements including obtaining EPA hazardous waste number (if you do not already have one), accumulating the waste no more than 90 days (although there are a few exceptions), a written contingency plan, periodic container inspections, a written training plan and annual or biennial report.

Hope this helps in making a right decision.