U.S. Secondary Containment Options That Pass SPCC, RCRA, and PE Review

Facilities storing oil or hazardous materials generally choose among six containment categories: dikes and berms, curbing and drip pans, sumps and collection systems, double-walled tanks or vaults, containment pallets, and sorbent materials. Which one fits depends on whether SPCC rules or RCRA rules govern the site, since each program sets its own sizing and documentation requirements. Sizing typically must cover the largest single container plus enough freeboard to handle precipitation, and every system needs a documented inspection and recordkeeping routine to back it up.

TL;DR:

• Facilities must choose containment options based on governing regulations, with SPCC requiring sizing for the largest container plus freeboard, and RCRA demanding at least 10% capacity or the largest container volume.
• Passive solutions like dikes and berms suit aboveground tanks, while active systems such as sumps need regular testing and maintenance to remain compliant.
• Sizing to a 24-hour storm event is recommended for stormwater capacity, with additional run-on control measures like catchment basins often needed.
• For impractical or remote sites, a formal engineer-certified demonstration of impossibility or an alternative monitoring plan can replace conventional containment.
• Proper recordkeeping, regular inspections, and timely repairs are essential for maintaining compliance and preparedness.

Table of Contents

• Quick checklist: containment option types and when they fit
• Regulatory requirements that determine acceptable secondary containment
• Sizing, layout, and design decisions: capacity, freeboard, and storm control
• Options by container type and site situation
• Impracticability, alternative measures, and the §112.7(k) route
• Inspection, maintenance and recordkeeping: practical schedules
• How to pick and implement the right option for your site
• A container-based perspective on containment builds
• Turnkey container solutions for your containment plan
• Sources
• FAQ

Quick checklist: containment option types and when they fit

Some options work passively with no moving parts, while others need active management. Matching the option to the container type, footprint, and maintenance capacity of a site keeps compliance manageable rather than becoming a recurring headache.

• Dikes and berms: passive, low-maintenance, and well suited to aboveground storage tanks with a fixed footprint.
• Curbing and drip pans: practical for indoor storage or small equipment where a full berm would eat too much floor space.
• Sumps and collection systems: active systems, often paired with pumps, that suit loading docks and areas with regular liquid transfer.
• Double-walled tanks or vaults: space-efficient alternatives to diking, particularly where land is tight.
• Containment pallets: modular and portable, ideal for drums and totes that move between sites or get reconfigured often.
• Sorbent materials: a supplemental measure, not a standalone containment system, best used alongside one of the above.

Cost and maintenance burden rise roughly in that same order. A concrete berm demands little upkeep beyond periodic inspection, while a sump with a pump needs testing, power, and a maintenance schedule.

Regulatory requirements that determine acceptable secondary containment

Two federal programs drive most containment decisions. Under the Spill Prevention, Control, and Countermeasure rule, 40 CFR §112.7© requires secondary containment sized to hold the entire capacity of the largest single container plus enough freeboard to handle precipitation, and it names dikes, berms, curbing, drip pans, sumps, gutters, booms, spill diversion ponds, retention ponds, and sorbent materials as acceptable measures. The rule is performance-based: any of these can satisfy it as long as the design actually prevents a discharge to navigable waters.

RCRA takes a more prescriptive approach for permitted treatment, storage, and disposal facilities. 40 CFR 264.175 requires an impervious base, drainage or elevation that keeps containers out of accumulated liquids, and capacity equal to 10% of the aggregate container volume or 100% of the largest container, whichever is greater, along with controls to prevent run-on unless extra capacity is added.

OSHA and NFPA guidance layer on additional considerations for aboveground tanks, and OSHA has historically accepted double-walled tanks as a diking alternative when overfill protection, vehicle protection, and alarms are in place. SPCC also carries its own inspection and recordkeeping expectations that run independently of which containment type a facility installs.

Sizing, layout, and design decisions: capacity, freeboard, and storm control

Freeboard gets added on top of that base number to account for rain accumulating inside the containment structure before it can be inspected and removed.

Run-on control matters as much as the containment volume itself. A facility either has to prevent surface water from entering the containment area or build in enough extra capacity to absorb it, commonly through catchment basins, trenches, or culverts that route water away from the storage footprint.

EPA’s inspector guidance on example calculations notes that sizing to a conservative 24-hour storm event is a defensible engineering practice, even though SPCC does not mandate a specific storm standard. Facilities that design to this benchmark tend to face fewer disputes during inspections.

Materials and structural choices round out the design. Concrete or lined earthen berms need imperviousness and properly sealed joints, and any containment area accessible to vehicle traffic should include physical protection against impact damage.

Options by container type and site situation

Drums and small containers typically use spill pallets or indoor curbing, and elevated storage on pallets can qualify for a RCRA exemption when containers hold no free liquids, though waste codes like F020 through F027 remove that exemption regardless of elevation.

IBCs and totes fit well with modular berms or curbed concrete pads that drain to a sump, giving facilities flexibility as inventory volumes shift.

Aboveground storage tanks generally rely on sized dikes or berms, though double-walled tanks offer a space-efficient alternative where OSHA and NFPA conditions on overfill protection and alarms are met.

Mobile containers and transfer areas call for temporary berms, portable catchment basins, and immediate spill response materials kept on hand for quick deployment.

Loading and unloading zones benefit from lined pads with drains routed to a holding basin, backed by administrative controls such as attended transfers and posted procedures during active loading.

Impracticability, alternative measures, and the §112.7(k) route

Sized secondary containment is not always feasible, particularly for long flowline runs or remote production equipment. EPA’s regional inspector guidance explains that a facility can only claim impracticability with a formal determination certified by a licensed Professional Engineer, backed by documentation showing why sized containment cannot be built.

Section 112.7(k) offers an alternative path for qualified oil-filled operational equipment: instead of a sized containment structure, the facility commits to an inspection and monitoring program, a written contingency plan, and documented commitments of manpower and equipment to respond to a release. Inspectors expect this documentation to be specific and current, not boilerplate. Facilities with a Facility Response Plan should confirm that alternative measures under §112.7(k) align with the response commitments already made in that plan.

Inspection, maintenance and recordkeeping: practical schedules

A workable inspection routine covers daily visual checks for standing liquid or damage, weekly checks of pumps and valves in active sumps, and monthly structural reviews of berms and curbing for cracks or settling. Corrective action needs to happen promptly, not at the next scheduled maintenance window.

Accumulated rainwater inside containment areas has to be inspected before release, checked for signs of oil contamination, and either released clean or removed and characterized as hazardous waste if contamination is confirmed. Bulk storage tanks generally need periodic integrity testing, with frequency increasing after any sign of corrosion or a near-miss release.

Records worth keeping for an audit include inspection logs, rainwater release checks, repair histories, and any PE-certified impracticability statements tied to §112.7(k) alternatives.

How to pick and implement the right option for your site

Start by identifying which program governs the site, SPCC or RCRA, then quantify container inventories and assess run-on exposure from nearby drainage. From there, shortlist containment options that fit the footprint and budget, and bring in a Professional Engineer early if impracticability or an alternative measure is even a possibility.

Ask any vendor for load capacity data, drainage compatibility, and material specifications a PE would need to sign off on. Implementation then moves through design, contractor and material specification, permitting, integrity testing, staff training, and folding the new containment into the facility’s SPCC Plan and emergency response procedures.

A container-based perspective on containment builds

Modified containers are commonly used at sites across the country, and hazmat storage units often come up in containment planning conversations. A container built with integrated curbing, a sump routed to a collection point, or lockable hazmat storage can simplify a containment layout that would otherwise require separate structural work. That said, any unit still needs to be sized and documented against the same SPCC or RCRA rules covered above, regardless of who supplies it.

— Conexwest

Turnkey container solutions for your containment plan

If your facility needs a hazmat storage unit that arrives ready to integrate curbing, sump routing, or lockable access into your containment layout, Hazmat containers and container customizations give you a specification-ready starting point rather than a ground-up build.

For temporary or project-based needs, storage containers for rent offer a way to add containment-ready storage without committing to a permanent structure, and delivery is available nationwide. Facilities weighing a permanent purchase against modification work can review shipping containers for sale and fabrication services to get a quote or request engineering layouts suited to PE review before you finalize a containment plan.

Sources

Consult EPA’s SPCC secondary containment guidance, the RCRA containers training module, and the eCFR text of §112.7 for authoritative rule language, and check with your state implementing agency for state-specific add-ons. Facilities evaluating drainage and capture hardware can also review LiquiDrainer’s containment resources for practical design references.

• Secondary containment for each container under SPCC | US EPA
• eCFR — 40 CFR §112.7: Discharge prevention measures and procedures | ECFR

FAQ

What are some examples of secondary containment?

Common examples include dikes, berms, curbing, drip pans, sumps, containment pallets, and double-walled tanks. EPA’s SPCC guidance lists these along with gutters, booms, and retention ponds as acceptable measures under §112.7©.

Do 5-gallon buckets require secondary containment?

Small containers like buckets can fall under SPCC or RCRA depending on what they hold and the total facility inventory, so there is no blanket exemption based on size alone. Facilities typically use spill pallets or curbed storage areas for buckets and drums to stay within the same rules that apply to larger containers.

What is the 110% secondary containment rule?

SPCC under 40 CFR §112.7© requires containment for the entire capacity of the largest single container plus freeboard, while RCRA’s 264.175 sets capacity at 10% of aggregate volume or 100% of the largest container, whichever is greater.

Is secondary containment a legal requirement?

Yes, for facilities covered by SPCC or by RCRA permit conditions for hazardous waste containers. The specific design and sizing obligations come from 40 CFR §112.7 for oil storage and from RCRA’s container storage rules for permitted hazardous waste facilities.