With 70,000 + estimated substations in the United States, many do not have secondary oil containment or SPCC contingency plans in case of a catastrophic oil release.
What is Secondary Containment?
Primary containment can consist of storage tanks, pipes, transportation vessels or other equipment used to store or transfer materials such as oil or other chemicals.
Primary containers can be designed with secondary containment that can include physical barriers, filtration and overflow systems.
The main function of backup or secondary fuel containment systems is to ensure that any discharge from the primary containment will not escape onto walls, floor or other part of the environment before a successful cleanup.
What Are the Requirements for Secondary Containment?
Under the authority of the Clean Water Act, the Oil Pollution Prevention Regulation set requirements for the prevention of, preparedness for and response to oil discharges at non-transportation-related facilities, with the goal of containing oil discharges and prevent oil from contaminating navigable waters.
In addition, the Spill Prevention, Control and Countermeasure (SPCC) requirements of the U.S. Environmental Protection Agency includes the “SPCC Rule,” which defines several classes of oil storage and requires either secondary containment or oil spill contingency plans (OSCPs) for bulk oil storage containers.
The EPA presents requirements for secondary containment in its hazardous waste storage regulation 40 CFR 264.175. This requires that a secondary containment system be impervious, free of gaps or cracks and compatible with the material being stored. It must have either a sloped design or a means for quick removal of leaking or spilled material.
The system must either prevent precipitation or run-on from entering or have capacity to contain it during heavy rainfall or equivalent conditions.
Material leaked or spilled into the secondary containment area must be removed as quickly as possible to avoid overflow and potential environmental contamination.
Tanks and their containment systems must be regularly inspected for signs of leakage, damage and deterioration.
The Institute of Electrical and Electronics Engineers (IEEE) Standard 980 reviews oil spillage regulations for electric supply substations and describes designs and materials for oil containment and control methods as well as dewatering systems. State and local requirements can also provide additional specifications for secondary containment.
Common Questions About Secondary Containment
How do you calculate secondary containment? The required volume of a secondary containment system is often calculated based on the primary containment capacity.
The EPA requires secondary containment to have capacity for at least 10 percent of the total volume of the primary container or 100 percent of the volume of the largest container, whichever is larger. The EPA provides resources for calculating the necessary containment volume in applications such as a square or rectangular berm for a single vertical cylindrical storage tank.
SPCC requirements apply to facilities that have either a total aboveground oil storage capacity of greater than 1,320 gallons or a total buried storage capacity of greater than 42,000 gallons. Calculate this amount based on the shell capacity, or maximum volume, of the containers, not the current amount of product, or operational volume.
Do double-walled tanks need secondary containment? Double-walled above-ground storage tanks (ASTs) qualify as secondary containment under certain EPA requirements, such as having overfill prevention measures and being constructed of approved materials.
Do 55-gallon drums need secondary containment? Secondary containment needs to be at least equal to the capacity of the original container, so a single 55-gallon drum, stored indoors, would need 66 gallons of containment capacity. With multiple drums, however, you may only need containment the size of the largest container. Four drums on a single containment pallet would still only require 66 gallons of containment capacity.
Solutions for Secondary Containment
There are multiple potential solutions for secondary containment requirements, depending on the storage needs.
Physical barriers such as raised berms provide one method of fuel containment. Booms are floating barriers, often made of metal or plastic, designed to contain oil and prevent its spread. They can often be placed between the primary storage and a nearby body of water.
Filtration can be used in tandem with containment systems. If wastewater passes through a filtration system, the filter can capture contaminants such as different levels of oil sheen.
Hybrid containment combines filtration with other forms of secondary containment.
If a containment system fails, repairing the existing containment can be more cost effective than replacing it outright. Spray coatings can be applied to second containment substrates to protect them from chemical damage and degradation. They can also be used to seal cracks, stop leaks and make other repairs.