Case Study 2: Review of Compressed Gas Waste Management

Compressed Gas Facility Going Out of Business

 A hazardous waste inspector received a notice from the U.S. Food and Drug Administration (USFDA) that a business that supplied medical oxygen was temporarily suspended from selling containerized oxygen because of various health violations. The inspector visited the site to see if there were any waste compressed gases on site that needed to be properly disposed.

The business owner was in poor health, and although he clearly wanted to comply with the corrections mandated by the FDA, he was unable to do so, and the oxygen supply business failed. The owner had stated that medical oxygen supply was the mainstay of his compressed gas business, so his inability to keep the oxygen business caused concern about the fate of the remaining compressed gas cylinders on site. In an on-site inventory, the inspector discovered over one thousand compressed gas cylinders, many of which were visibly corroded; some were stored in trailers and other buildings on and off site.

As discussed in Chapter 2, "Identification of Hazardous Waste", waste compressed gases with pressure over 1 atmosphere, that are flammable or that will support combustion, are D001 hazardous waste. There were hundreds of oxygen and acetylene cylinders scattered throughout the property, because the facility refilled these cylinders for welders throughout the area. There were cylinders of nonhazardous gases such as nitrogen, argon, and freon, together with some fairly uncommon gases. The most poisonous gas found on site was phosgene, a gas that was used as a nerve agent in World War I, but that is still used as a reagent in the pharmaceutical industry today.

Of even greater concern were other types of compressed gases that were unstable or even explosive. One example of these is hydrogen gas, highly explosive at room temperature and pressure. Another potentially unstable and explosive gas is contained in old acetylene containers. If acetylene gas is pressurized in its pure form over 15 PSI, it breaks down or separates into carbon black and hydrogen gas, a highly unstable and explosive mixture. If acetylene gas is placed in a container with a fabric "wick" containing a solvent such as benzene or acetone in the center of the tank, it is stable up to 1500 PSI. A serious problem can arise if the acetylene cylinder is stored for a long period, because the solvent that stabilizes the gas can diffuse out of the wick and container, leaving a very unstable, explosive container.

When the business shut down a few weeks later, the facility manager vented all of the dangerous containers on site (except for the poisonous gases). Those empty containers were hauled off site for scrap metal recovery. This incident had a satisfactory ending in that all of the gas cylinders were removed without incident, the building was demolished, and a new business has been built on the same site.

The hazardous wastes generated in this case were predominantly D001 (ignitable), but because they were released directly to the environment and they had no measurable weight, after the containers were vented, it was as though the wastes had never been generated.