Do You Need Secondary Containment? Requirements and Applications

What Is Secondary Containment?

Secondary containment refers to structures or systems designed to capture and contain spilled liquids when primary storage containers fail. Unlike primary containment (the tank, pipe, or vessel holding the product), secondary containment provides a backup barrier between spilled materials and the environment. This includes berms, dikes, vaults, double-wall tanks, and lined containment areas that surround or enclose primary storage systems.

The concept operates on the principle that all containers will eventually fail, whether through corrosion, mechanical damage, human error, or natural disasters. Secondary containment ensures that when failure occurs, spilled materials remain controlled within a designated area rather than contaminating soil, groundwater, or surface waters. This protection proves critical for both environmental safety and regulatory compliance.

Secondary containment systems must be impermeable to the stored materials and capable of withstanding the physical and chemical properties of potential spills. They require proper design, construction, and maintenance to function effectively when needed. The system must also provide access for inspection, maintenance, and emergency response while maintaining containment integrity.

Effective secondary containment goes beyond simply building walls around tanks. It requires integrated design considering drainage, ventilation, access, and emergency response needs. The system should facilitate normal operations while providing reliable protection against spills, making it both a safety measure and an operational necessity for responsible facility management.

When Is Secondary Containment Required?

Federal SPCC regulations require secondary containment for most oil storage facilities that could discharge to navigable waters. Any facility storing more than 1,320 gallons of oil in aboveground containers (55+ gallon capacity) or 42,000+ gallons underground typically needs secondary containment if spills could reach waterways. This includes the vast majority of oil and gas operations, from small equipment yards to major refineries.

State regulations often exceed federal requirements, with some states requiring secondary containment for smaller storage volumes, additional product types, or facilities in sensitive environmental areas. California, for example, has stricter requirements for facilities near water supplies or in seismically active zones. Texas requires enhanced containment for certain upstream operations in environmentally sensitive areas.

New tank installations almost universally require secondary containment under current regulations, while existing facilities may need retrofitting based on age, location, and compliance history. The EPA has increased enforcement focus on secondary containment violations, making compliance assessment and upgrades a priority for many operators.

Industry-specific requirements add additional layers of obligation. Underground storage tanks at retail fuel stations must have secondary containment under federal UST regulations. Pipeline facilities require containment at pump stations, valve assemblies, and loading areas. Marine terminals face Coast Guard requirements for waterfront operations, while refineries must meet both SPCC and Clean Air Act containment standards.

Types of Secondary Containment Systems

Bermed earthen containment uses soil, clay, or synthetic liners to create containment areas around storage tanks. These systems work well for large aboveground tanks in rural settings where space allows for adequate berm construction. Proper design requires impermeable liners, adequate drainage systems, and access ramps for maintenance. Earthen berms need regular inspection for erosion, settlement, and liner integrity.

Concrete containment systems provide durable, long-lasting protection through reinforced concrete walls and floors. These systems excel in applications requiring frequent cleaning, chemical resistance, or heavy traffic. Concrete containment allows precise capacity control and integration with drainage systems, though higher initial costs may limit application to critical areas or high-value installations.

Vault containment completely encloses storage tanks within concrete or steel structures, providing maximum environmental protection. Vaults work particularly well for underground tanks, sensitive locations, or areas with limited space for surface containment. While expensive to construct, vaults offer superior protection and can integrate storage, containment, and monitoring functions in compact installations.

Double-wall tank systems provide integrated primary and secondary containment within a single manufactured unit. The outer wall serves as secondary containment while interstitial monitoring detects primary tank failures. These systems offer space efficiency and simplified installation but require specialized maintenance and may have limited capacity compared to separate containment areas.

Designing Effective Secondary Containment

Capacity calculations form the foundation of effective secondary containment design. The system must hold at least 110% of the largest container volume within the containment area, plus freeboard for precipitation. Multi-tank installations require either 110% of the largest tank or 100% of the largest plus 10% of others, whichever is greater. Account for tank foundations, piping, and equipment displacement when calculating available volume.

Drainage design prevents precipitation from compromising containment capacity while ensuring spilled materials stay contained. Install drainage systems with normally-closed valves that operators can control during emergencies. Size drainage to handle local precipitation patterns while maintaining required freeboard. Consider separate clean water and contaminated water drainage systems where regulations permit.

Material compatibility ensures containment system integrity when exposed to stored products. Concrete may require special coatings for certain chemicals, while steel systems need corrosion protection appropriate for the operating environment. Liner materials must resist degradation from both stored products and environmental conditions like UV exposure, temperature cycling, and soil chemicals.

Access and safety features enable effective operation and emergency response within containment areas. Provide adequate access for routine maintenance, inspection, and emergency response vehicles. Install proper lighting, ventilation, and communication systems for worker safety. Consider fall protection, confined space requirements, and emergency evacuation routes when designing containment layouts. Integrate fire protection systems where required by code or prudent practice.