Do Portable Containers Need Secondary Containment?
Quite possibly, yes! Below is a summary of some commonly applicable containment requirements.
SPCC - If your facility has the capacity to store more than 1,320-gallons of oil, it is regulated under EPA's Spill Prevention, Control and Countermeasures (SPCC) regulations and all oil containers greater than 55-gallons need to be within sized secondary containment. The volume of this secondary containment should be the capacity of largest container, plus a 25-year, 24-hour storm event. This secondary containment must also be sufficiently impervious. (see 40 CFR 112.8(c)(11))
Hazardous Waste Regulations - If your site generates more than 2,200-pounds of hazardous waste per month, it is considered a large quantity generator. As a large quantity generator, all hazardous waste containers need to be covered and within impermeable containment that is at least 10% of the total volume of the containers or 100% of the volume of the largest container, whichever is greater. (see 40 CFR 264.175(b))
Storm Water Regulations - If activities at your site fall under a regulated Standard Industrial Classification (SIC) code, you must either apply for a No Exposure Certification or coverage under a Storm Water Permit. If you need to pursue a No Exposure Certification, providing secondary containment and a cover for portable containers will be important.
For example, in its No Exposure Certification Application, the State of Colorado states that "In general, secondary containment that is adequately engineered to prevent any failure, leakage or overflow such that there would simply be no discharge from that area of the facility would qualify for the no exposure exclusion."
If you need to apply for a permit, secondary containment for portable containers becomes an important best management practice.
Fire Code - Both the International Fire Code and Uniform Fire Code require that secondary containment be provided for certain liquids (including corrosive, flammable, toxic and combustible liquids) if an individual container exceeds 55 gallons or the aggregate capacity of multiple containers exceeds 1000-gallons. Generally, these containments shall be designed to contain the largest container plus 20-minutes of fire-extinguishing water if indoors or rainfall from a 24-hour, 25-year storm event if outdoors.
How Much Precipitation is in a 25-year, 24-hour storm event?
It depends on your location. The simplest way to determine the inches of precipitation associated with your location is to consult NOAA's website. Once you determine the inches of precipitation associated with a 25-year, 24-hour storm event, all you need to do is convert it to feet (divide inches by 12 to get feet) and multiply by the square footage of your containment. This will give you the volume of precipitation in cubic feet, which can be converted to gallons by multiplying it by 7.4805.
What Does EPA Mean By "Sufficiently Impervious"?
EPA does not provide specific parameters such as permeability or hydraulic conductivity for determining whether containment is "sufficiently impervious." Rather, in Chapter 4 of its SPCC Guidance for Regional Inspectors, EPA states that "secondary containment structures such as dikes, berms and retaining walls can be considered sufficiently impervious as long as they allow for cleanup to occur in time to prevent a discharge to navigable waters or adjoining shorelines."
How Can SPCC Software Help?
Software, such as the Ecesis SPCC Software automatically calculate tank volumes and containment capacities. They also enable quick updating and generation of SPCC Plan components (such as tank inventories), track integrity testing requirements, and enable SPCC inspections on mobile devices such as phones and tablet.