Unlabeled organic solvent waste was poured into a larger 4-liter container of aqua regia (concentrated hydrochloric acid and concentrated nitric acid). The aqua regia waste container was recapped, the hood sash was closed and left alone. Within minutes, lab occupants heard a whistling sound, followed by a loud explosion. When mixed, the incompatible wastes created a rapid reaction and over-pressurization of the container resulting in an explosion that destroyed the hood and cracked an exterior window. Luckily, no one was injured.
Lessons Learned
- Remember to immediately label all waste containers.
- If you encounter an unknown waste, ask other staff members or your supervisor to help identify the waste. If the waste cannot be identified, contact EHS for assistance. Keep all unknown waste separate. Never mix unknown wastes together.
- Conduct and document lab-specific waste collection training. Follow best practices for collection, labeling and procedures for handling unknown waste.
- Review and update standard operating procedures (SOP’s) as needed to reflect lab specific or additional departmental waste collection procedures and practices.