In 1995, total hazardous waste generation equaled 214 million tons according to EPA's National Biennial RCRA Hazardous Waste Report. If you generate and store hazardous waste at your workplace, you have undoubtedly heard of RCRA Containment Requirements.
Here's what the EPA says about containment: According to 40 CFR 264.175 (b) (3) , "...The containment system must have sufficient capacity to contain 10% of the volume of the containers or the volume of the largest container, whichever is greater...". That means that if you need containment for four 55-gallon drums, 10% of the total capacity of the containers would be 22 gallons. In this case, however, the volume of the largest container is 55 gallons. In order to be the correct size, the containment unit must have a sump capacity of 55 gallons, since that is the larger of the two amounts.
When storing hazardous waste, make sure that you are using a containment unit specifically designed for that purpose. RCRA has identified key design features that containment units must possess in order to comply. Once you have identified the containment unit that meets your needs, there is one more thing to keep in mind: containment units must be stored under a covered structure like a tarp or a hard cover to prevent rainwater run-on from entering the unit.