Is this important?
It's very important if your program is near the 100 kg or 1,000 kg per calendar month for generation of non-acute hazardous waste by conditionally exempt or small quantity generators, respectively. Careful counting may bring the program under the limit and save unnecessary regulatory aggravation.
Only the net weight of RCRA-regulated waste counts toward monthly accumulation limits. [1], [2]
Avoid unnecessary labor! Use this section only if it is likely to bring your monthly total below one of the generator status cutoff points or if you need the data for other purposes.
Manifest data and vendor reports for labpacked waste usually include gross weight of waste and individual containers and may also include overpacking material. But how to measure net weight? Emptying containers to weigh the waste separately would present significant hazards (!) and is a poor use of time.
- Create a list of tare weights of common containers to give a defensible basis for estimating net weights. (Subtract the tare weight from the total weight of container with waste)
- Don't count non-regulated chemical waste as RCRA hazardous waste just because you ship it with hazardous waste.
- Keep good records and documentation for inspectors. For example, if you subtract tare weights of containers, be prepared to show how you determined the tare weights
