Secondary containment systems are a regulatory requirement for facilities that store, handle, or process hazardous materials, fuels, chemicals, and other substances that pose environmental risks. Traditional containment systems built from concrete, HDPE liners, or epoxy coatings have well-documented weaknesses. Polyurea has emerged as a highly effective alternative, offering superior performance in the precise conditions that secondary containment systems must endure.
What Is Secondary Containment?
Secondary containment refers to a barrier system designed to capture and hold spilled or leaked materials from a primary container, such as a storage tank, drum, or process vessel. Regulatory frameworks including EPA 40 CFR Part 264 (Resource Conservation and Recovery Act), SPCC (Spill Prevention, Control, and Countermeasure) regulations, and various state environmental codes require secondary containment capable of holding 110 percent of the volume of the largest container in the containment area.
The containment system must remain liquid-tight for the duration of its service life without allowing the contained material to migrate into soil or groundwater. This is a demanding requirement that exposes the weaknesses of concrete-only systems, which crack over time, and thin HDPE liners, which can be punctured during operations.
Why Traditional Systems Fall Short
Concrete is the default material for secondary containment berms and pads, but concrete alone is not a liquid-tight barrier. Freshly placed concrete is porous and will absorb hydrocarbons and chemicals unless sealed. More critically, concrete cracks due to thermal expansion and contraction, settlement, and structural loading. Even hairline cracks allow liquids to migrate through the slab and into the subgrade.
Coating concrete with epoxy addresses porosity but does not resolve the cracking problem. Epoxy coatings are rigid and will crack when the underlying concrete moves. A cracked epoxy coating in a containment system is worse than no coating because it creates a false sense of compliance while providing no actual barrier to liquid migration. These same limitations apply to urethane coatings applied to concrete secondary containment structures.
How Polyurea Solves the Problem
Polyurea applied as a seamless liner over concrete secondary containment structures bridges cracks, accommodates substrate movement, and creates a true monolithic barrier. With elongation values of 200 to 500 percent, polyurea stretches with substrate movement rather than cracking with it. Tensile strengths of 2,000 to 4,000 psi ensure the membrane remains intact under operational loads including vehicle traffic, equipment vibration, and forklift impacts.
The seamless nature of sprayed polyurea eliminates the seams, overlaps, and mechanical fasteners that are common failure points in sheet membrane systems. A properly applied polyurea secondary containment lining becomes a continuous, jointless barrier from floor to berm to wall, with no paths for liquid to bypass the coating.
Chemical Resistance Considerations
Polyurea is not a universal chemical barrier. It offers excellent resistance to hydrocarbons, petroleum products, many solvents, and mild acids and bases. For highly concentrated acids, chlorinated solvents, or other aggressive chemicals, specialized formulations or alternative liner systems may be required.
Always obtain an immersion test or chemical resistance data for the specific chemicals that will be contained before selecting a polyurea system for secondary containment. Reputable polyurea manufacturers maintain chemical resistance guides for their products. When in doubt, contact the manufacturer’s technical team directly for guidance. See our industry resources page for relevant standards including ASTM testing methods used to evaluate chemical resistance.
Application Advantages in Containment Settings
One of the most practical advantages of polyurea in secondary containment applications is its ability to be applied to complex geometry. Berms, curbs, floor drains, sumps, and transitions from floor to wall are all potential weak points in containment systems. Polyurea spray application conforms to any geometry, coating inside corners, transitions, and penetrations without the gaps and bridging problems that plague sheet membrane systems.
Rapid cure also means that large containment areas can be coated and returned to service within a single work shift, minimizing operational downtime for the facility. Compare this to epoxy coatings requiring multiple coats with 8 to 24 hour cure windows between applications, which can result in a week or more of downtime for large containment areas.
Integration with Pipeline and Infrastructure Protection
Many facilities that require secondary containment also have pipeline connections entering and exiting the containment area. Polyurea can coat both the containment area and the pipeline penetrations in a single application, creating a continuous barrier system. Our article on how polyurea pipeline coatings changed pipeline protection and repair covers how polyurea performs on the pipeline infrastructure connected to these facilities.
Regulatory Compliance Documentation
For facilities operating under SPCC plans or RCRA regulations, documentation of the secondary containment system’s integrity is essential. Specify polyurea systems that can be tested for adhesion (ASTM D4541), measured for film thickness, and visually inspected for continuity. Third-party holiday testing (spark testing) can verify the absence of pinholes or thin spots in critical containment applications.
Getting the Application Right
Secondary containment is a liability-critical application. A failure that allows hazardous materials to escape into the environment can result in regulatory fines, remediation costs, and significant legal exposure for the facility owner. This means surface preparation, primer selection, and application quality are all non-negotiable.
Contractors working on secondary containment systems should have specific experience with these applications and a demonstrated understanding of the regulatory requirements their work must satisfy. Our guide on evaluating polyurea training programs can help facility owners identify qualified applicators. Ready to become a qualified applicator yourself? Visit our Become an Applicator page to get started.
For a broader view of where polyurea is being used in industrial and environmental protection settings, visit our polyurea applications page. You can also review key industry standards in our industry resources section.
