If your California facility stores hazardous waste, you have secondary containment requirements you need to know about. Under Title 22 of the California Code of Regulations, specifically 22 CCR 66265.193, every hazardous waste tank system must have secondary containment that prevents releases from reaching soil and groundwater. That’s not optional. It’s not a guideline, it’s a mandate. When we inspect facilities, inadequate secondary containment is the single most common deficiency we find. The good news: it’s fixable, and understanding the requirements now means you can get it right before an inspection happens.
What Secondary Containment Is
Secondary containment is a physical barrier designed to capture a release from a storage container before that release reaches the ground or water. It’s a second line of defense. If your primary tank leaks, the containment structure catches it. That’s the concept. In practice, secondary containment takes several forms: double-walled tanks where the outer wall serves as the containment structure, bermed areas lined with epoxy or chemical-resistant coatings, concrete vaults, or lined sumps. The specific type depends on your facility layout, tank configuration, and the nature of the waste being stored.
Think of it this way: your tank is your primary barrier. Your containment is your backup plan. If that backup plan isn’t in place or isn’t adequate, you’re exposing your facility to regulatory citations, environmental liability, and potential cleanup costs that far exceed the cost of building proper containment in the first place.
The Capacity Rule
Here’s where most facilities slip up. Containment capacity isn’t arbitrary. The regulation is specific: your containment must hold at least 100% of the largest tank in that area. So if your biggest tank holds 10,000 gallons, your containment structure must hold 10,000 gallons. This is the minimum, not the target. Not 95%. Not 90%. 100% or it fails inspection.
For outdoor installations, add another layer: you also need to account for the 25-year, 24-hour precipitation event for your location. This is a meteorological standard based on historical rainfall data for your specific region in California. If you’re in the Central Valley, that number is different from coastal areas. You have to make room for that rain. And you subtract tank displacement from your available containment capacity, if your tank takes up 3,000 gallons of space inside the berm, you only have 7,000 gallons of net capacity to work with.
Note: if your storage area also includes smaller containers (drums, totes) alongside tanks, separate container accumulation area rules may apply. Container storage areas have their own containment requirements under different regulatory sections. The 100%-of-largest-tank rule described above applies specifically to tank system containment under 22 CCR 66265.193.
Common Capacity Shortfalls We Find
The most frequent violation is a berm that’s too small. A facility has a 5,000-gallon tank but only measured containment for 4,500 gallons. Another facility has a bermed area but forgot to account for tank displacement, they measured the berm alone and assumed they had plenty of space. A third facility has outdoor containment but wasn’t told about the precipitation requirement and didn’t add that volume. Each of these sounds small until the fire department inspects it and marks it as deficient.
Material Compatibility Matters
Containment material must be compatible with the waste it will catch. This isn’t guesswork. Asphalt dissolves under petroleum products. Unlined carbon steel corrodes from corrosive waste streams. Polyethylene degrades from solvents. If you’re storing a strong acid, your containment can’t be steel. If you’re storing flammable solvents, you need a lining that won’t degrade over time.
Check the material specifications for your waste. Review any safety data sheets (SDS) for the specific chemicals you store. Inspect your material regularly for signs of incompatibility, surface softening, discoloration, chalking, or structural weakness. If you find degradation, it’s time to replace or reinforce the lining.
Containment Must Be Maintained Dry
Your containment area shouldn’t accumulate rainwater or residual material. We regularly find berms holding six inches of standing water, or sumps with sediment and spill residue that haven’t been cleaned. Water sitting in your containment for months degrades linings, masks cracks in concrete, and prevents you from actually detecting a new release when it happens. It also creates a secondary environmental hazard if that water becomes contaminated and then spills over.
Establish a documented removal protocol. Check after heavy rain. Remove accumulated water before it becomes a problem. Document what you found and when you removed it. If you find a spill or leak, clean it up and document the removal, including the date and what was spilled. Keep these records, inspectors look for them as evidence of ongoing maintenance.
How This Connects to Tank Certification
Tank certification under 22 CCR 66265.192 includes an evaluation of your secondary containment. We don’t just assess the tank itself, we assess the entire system. Is the containment in good condition? Is the capacity adequate? Is it maintained dry? Is the material compatible with your waste? These are part of the certification report. If deficiencies exist, we document them and recommend remediation. You can fix issues before your fire department issues a citation.
What Your Fire Department (CUPA) Looks For
In California, the local fire department often serves as the CUPA (Certified Unified Program Agency) the agency that oversees hazardous waste storage compliance at your facility. During their inspections, containment is front and center. They look at the same things we do: capacity, material condition, compatibility, and maintenance. If they issue a citation for inadequate containment, the clock starts ticking. You’ll have a deadline to correct it. That’s when most facilities call us to understand what needs to change and how to fix it.
Certification is one step in compliance. Maintaining your containment is ongoing. The difference between a facility that stays compliant and one that gets cited repeatedly is often just documentation and regular inspection.
Get Your Containment Right
Secondary containment isn’t complicated once you know the rules. Inadequate capacity, material degradation, and accumulated water are all preventable. Start by reviewing your existing containment, measure it, document the material, verify it’s compatible with your waste stream, and establish a maintenance schedule. If you’re not sure about any of these elements, bring in someone who can assess it objectively.
The cost of fixing containment now is always lower than the cost of remediating a release, defending a citation, or paying for environmental cleanup. And it keeps your facility compliant.
If you’re unsure whether your containment meets California requirements, we can assess it. Call (925) 551-7300 or book a meeting. Tell us about your storage area, tank count, containment type, any recent citations or concerns. We’ll visit your facility, evaluate what you have, and tell you exactly what’s needed to stay in compliance. We handle it from there.
Frequently Asked Questions
How much secondary containment capacity do I need?
Under California regulations, your secondary containment must hold at least 100% of the volume of the largest tank in that storage area. This is the minimum requirement. For outdoor installations, you may also need to account for rainfall accumulation.
Can I use a bermed area instead of a double-walled tank?
Yes, as long as the berm system meets the containment capacity requirements and is constructed with materials compatible with the waste being stored. Bermed areas with chemical-resistant coatings, concrete vaults, and lined sumps are all acceptable containment methods.
What happens if my containment fails during a CUPA inspection?
The CUPA will issue a finding, and you will typically have a set period to correct the deficiency. In most cases, this means repairing or upgrading your containment to meet the 100% capacity requirement. If the deficiency poses an immediate risk, the timeline may be shorter.
Do I need separate containment for incompatible wastes?
Yes. Incompatible wastes must be stored in separate containment systems. If two waste streams could react with each other, they cannot share a secondary containment structure.
