Secondary Containment
Secondary containment is the second line of defence against the release of liquids, oils or chemicals on industrial sites. Sitting beneath or around a primary vessel, it captures any spill, leak or overflow before it reaches the ground, drains or watercourses, protecting people, assets and the environment when primary containment fails.
What Is Secondary Containment?
Secondary containment is an engineered barrier installed around, beneath or beside primary storage vessels, pipelines or process equipment. It captures any product that escapes the primary vessel, through a slow leak, a sudden rupture, an overfill or an operational spill, and holds it safely in a defined bunded area until it can be recovered, treated or disposed of.
Primary containment is the vessel itself: the tank, IBC, drum or pipe. Secondary containment is everything wrapped around it to catch a release if it fails. Primary holds the product in normal operation; secondary only comes into play when primary fails. Good design treats both as a single engineered system, not isolated components.
When Is Secondary Containment Required?
Common Secondary Containment Structures
Concrete bund walls surrounding bulk storage tanks
Bund floors and plinths beneath tank bases
Spill containment bunds for drum and IBC storage
Oil secondary containment for diesel, heating oil and fuel storage installations
Chemical storage pits, sumps and catchpots
Tanker offloading and loading bays
Process and plant room floors
Trench, gully and channel linings
Secondary pipework containment trenches
Laboratory, cleanroom and pharmaceutical containment areas
Wastewater treatment bunds and effluent handling structures
Secondary Containment Performance Requirements
Recommended Secondary Containment Systems
The right resin for a secondary containment system depends on the worst credible spill the bund has to hold, not just the routine exposure. Because secondary containment has to perform as a single envelope across both walls and floors, the same chemistry usually runs across the whole bunded area:
Epoxy Resins
The best material for full-envelope hydrocarbon and dilute chemical containment, suitable across walls, floors and the coved fillet between them. Most oil secondary containment installations are based on a tuned epoxy build-up.
Polyurethane Resins
Used when the whole envelope has to absorb thermal and structural movement without breaking continuity, particularly on external compounds where wall and floor cycle together through the seasons.
Polyurea Resins
Rapid-cure systems that let a complete secondary containment envelope be installed in a single mobilisation, ideal where a planned shutdown cannot tolerate the time required for slower-curing chemistries.
Vinyl Ester Resins
Selected where the worst credible spill is a concentrated mineral acid, oxidiser or sour service stream, and the entire containment system has to be uprated above standard epoxy chemistry.
Novolac Epoxy Resin
Full-envelope uprating for sites with multi-chemistry exposure, elevated service temperatures and aggressive solvents, applied consistently across walls, floors and detail areas so that the bund performs as one engineered system.
Recommended Secondary Containment Build Up Methods
A secondary containment system only performs if the whole envelope works as one, from the top of the wall, down the vertical face, across the coved fillet, over the floor and through every penetration. Every method below is selected with that integrated envelope in mind:
Site Fabrication
For non-standard secondary containment geometries: compartmentalised bunds, multi-vessel compounds, irregular plinths and tank skirts where standard sections cannot wrap a primary vessel cleanly. We fabricate cover plates, edge profiles and tailored details on site so the envelope remains continuous around every obstacle.
Lining and Levelling
Restoring a single, coherent fall across the entire bunded area towards one valved drainage point, rather than the patchwork of low spots that older bunds often present. Lining and levelling is critical when a containment system has been altered, extended or repeatedly patched over the years.
Protective Coatings
Multi-coat envelopes engineered as a single specification across walls, floors, fillets and detail areas, so that one chemistry and one performance profile run continuously across the whole containment system rather than being switched mid-bund.
Bund Lining Repairs
Targeted remediation where one element of the envelope has failed, a wall section, a floor panel, a corner without taking the whole secondary containment out of service. Each repair is specified to bond into the existing envelope so the integrity test still passes across the bund as a whole.
Trowel Applied Mortar Systems
Used selectively within a containment system at hot spots that the rest of the envelope cannot match unaided, including tanker offloading zones, drum decks and any area where mechanical or thermal loading would otherwise compromise the bund as a whole.
Surface Preparation
Applied consistently across every surface inside the envelope, walls and floors alike, so the same primer-and-coating system bonds reliably from cove to crest. Mixed preparation standards are the most common cause of a containment system that fails one part of an integrity test while passing another.
Key Secondary Containment Design Considerations
Secondary Containment Regulatory Compliance
A correctly specified and installed secondary containment system supports compliance with the following regulations and guidance:
Not sure which system is right for you?
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Secondary Containment FAQs
Primary containment is the vessel itself (the tank, pipe, IBC or drum holding the substance), secondary containment is the bund engineered around it to catch any leak, and tertiary containment is the wider site infrastructure, including interceptors, oil-water separators, drainage trenches and surface bunding, that catches anything escaping primary and secondary together. Each layer is designed to fail safely into the next.
A correctly specified, properly applied and well-maintained secondary containment lining typically delivers 15–25 years of compliant service across most UK industrial duties. Detail and joint sealants normally need replacement inside that window, typically every 7–10 years, while the field of the lining usually outlasts them.
Yes, every secondary containment specification we issue is bespoke to the substance, substrate, geometry, regulatory framework and operational constraints of the specific asset. There is no standard package: chemistry, build-up method, capacity calculation, drainage detail and inspection regime are all matched to the site rather than picked from a catalogue.
Outdoor secondary containment is exposed to thermal cycling, UV degradation, freeze-thaw on buried elements and rainfall load on the bund’s freeboard, all of which influence material selection and capacity calculations. We specify UV-stable polyurethane or aliphatic topcoats on external bunds, and design freeboard to absorb a 24-hour design storm event alongside firefighting water.
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