The California monthly DUO inspection, run from your phone.
California requires a monthly Designated UST Operator visual inspection (Appendix 4, 23 CCR 2631). The full California walkthrough is built into TankBinder, so the inspection you do is the one your local agency expects.
23 CCR 2631 · monthly cadence · keep records 1 year.
What the California monthly inspection captures.
The full Appendix 4 section set, built into TankBinder and run from your phone.
California is one of the most demanding states for underground storage tanks. Every month, the site's Designated UST Operator (DUO), who must hold an ICC California UST System Operator certification, performs a documented visual inspection of every tank system. The form California operators use is the Appendix 4 Designated UST Operator Visual Inspection Report, an official state form. It is not a quick checklist: it walks the operator through numbered compliance issues, prior inspection history, release-detection alarms, and a containment-by-containment check of every sump, spill bucket, and under-dispenser area, then captures testing and maintenance due dates, operator training, and sign-offs from both the operator and the owner.
TankBinder is at full fidelity for California today. The complete Appendix 4 walkthrough is built into the app, so the inspection you do on your phone is the one your local agency expects, and the file you produce is the one they ask to see.
Federal penalties for tank violations run into the thousands of dollars per day, per violation, and missing records are among the most common citations.
Per site. The Appendix 4 walkthrough, the reminders, and a one-tap inspector-ready file, for less than a single late-record penalty.
The DUO already does the work. Stop letting the binder lose it.
The back-room binder
- × Appendix 4 reports you have to remember to file, and can misplace.
- × No warning before the monthly DUO inspection slips past.
- × A scramble through paper when the local agency is standing there.
- × A generic checklist that may not match the California form.
- × English only, even when your crew is not.
TankBinder for California
- ✓ Every Appendix 4 inspection timestamped and impossible to misfile.
- ✓ A reminder by email before every monthly DUO inspection.
- ✓ The complete inspector file in one tap, any time.
- ✓ The actual Appendix 4 form, built in, with both sign-offs.
- ✓ The whole app in English and Spanish.
Simple pricing, per site.
Less than the cost of one late-record violation. Save 20% paid yearly.
- The California Appendix 4 walkthrough
- Deadline reminders
- One-tap inspector-ready file
- Everything in Solo, up to 5 sites
- One dashboard across all your sites
- English and Spanish
- Everything in Multi, unlimited sites
- Generator and non-retail sites
- One flat price, no per-site fees
Every plan includes the California Appendix 4 form, deadline reminders, and the inspector-ready file. Cancel anytime; your records export with you.
Run your next California inspection with us.
Get set up in about 15 minutes. Create your account, add your sites and tanks, and the California Appendix 4 walkthrough is ready for your first DUO inspection, so you are inspection-ready from day one.
- ✓Up and running the same day.
- ✓Your state's form and calendar, loaded for you.
- ✓You walk away with a real inspector-ready file.
Create your account
Sign up, add your sites, and the California Appendix 4 walkthrough is ready in the app. Walk your first DUO inspection today.
Create your accountSolo $39, Multi $69, Fleet $99 per month. Save 20% paid yearly. Cancel anytime; your records export with you.
Already have an account? Log in. Want a hand getting set up? Contact us.