ATG Troubleshooting: Tank Gauge Alarms Explained

Why ATG Alarms Demand Immediate Attention

Your automatic tank gauge (ATG) is the central nervous system of your underground storage tank (UST) compliance program. When it alarms, it’s not a suggestion — it’s a regulatory event. Under 40 CFR Part 280, EPA’s federal UST regulations, operators are required to respond to monitoring system alerts, document their actions, and in many cases, report to state agencies within strict timeframes.

Ignoring or silencing ATG alarms without investigation can expose your facility to penalties of up to $29,980 for each tank for each day of violation (42 U.S.C. 6991e(d)(2), as adjusted by 40 CFR 19.4), plus whatever your state program assesses on top. More critically, an uninvestigated alarm could mean product is leaking into soil and groundwater right now.

This guide walks through the most common Veeder-Root alarms and other ATG system alerts, what they mean in plain language, and exactly what you’re required to do about them.

Understanding Your ATG System’s Alarm Categories

Most ATG systems — including the widely installed Veeder-Root TLS-350 (end-of-sale in the U.S. since 2021), TLS-450PLUS, TLS4 and TLS4B — sort these messages into two categories, not a numbered priority scale. Veeder-Root defines them this way:

Your Class A/B/C operator training (required under 40 CFR 280.241 and 280.242; 280.245 covers only the documentation of that training) should have covered how to read and respond to these levels. If your Class C operators — the frontline staff working the register — don’t know how to identify an active alarm on your ATG console, that’s a compliance gap you need to close today.

The Most Common ATG Alarms and What They Mean

1. Leak Alarm (Tank Leak / Line Leak)

This is the alarm no operator ever wants to see. A tank leak alarm fires when the ATG’s statistical leak detection software detects a rate of product loss that exceeds the rate the method must be able to detect. Automatic tank gauging must be capable of detecting a 0.2 gallon per hour leak rate, tested at least every 30 days (40 CFR 280.43(d)). The 0.1 gallon per hour rate belongs to tank tightness testing (40 CFR 280.43(c)), which is a separate method — not what your ATG runs on its monthly schedule.

A line leak alarm indicates the pressurized piping system has triggered the electronic line leak detector (ELLD), usually because flow rate or pressure drop suggests product is escaping the line rather than reaching the dispenser.

What to do immediately:

1. Do not dispense product from the affected tank or line until the alarm is investigated.
2. Check for obvious physical signs: fuel odors, wet soil near tank field, dispenser sump flooding.
3. Contact your ATG service technician or certified leak detection specialist.
4. Check your state’s reporting deadline — 40 CFR 280.50 requires a suspected release to be reported to the implementing agency within 24 hours, or another reasonable period the agency specifies.
5. Document everything: time of alarm, who responded, actions taken.

Regulatory Note: Under 40 CFR 280.50, the conditions listed in that section — including monitoring results and alarm investigations that indicate a release may have occurred — must be reported to the implementing agency within 24 hours, or another reasonable period specified by the implementing agency. Failure to report is itself a separate violation from the leak itself. Confirm the window your own state program uses.

2. High Water Alarm

Water in your fuel tank is both a product quality problem and a compliance signal. ATG probes measure water at the bottom of the tank using a float that responds to liquid density. A high water alarm triggers when the water detected in the tank exceeds the alarm limit programmed into the console — Veeder-Root documents it as “water detected in tank exceeds programmed alarm limit,” with a separate High Water Warning at a lower programmed limit. There is no fixed federal or default threshold, so check what your own console is set to.

Common causes include a failed fill cap seal, condensation accumulation, a compromised tank bottom, or water intrusion through a manway. In UST compliance terms, an unexplained presence of water in the tank is one of the “unusual operating conditions” that 40 CFR 280.50(b) requires you to report to the implementing agency within 24 hours, unless the equipment is found not to be releasing regulated substances and any defective component is immediately repaired or replaced.

Resolution steps:

• Use water-finding paste or a bottom sample to confirm the ATG reading independently.
• Arrange for water removal via an authorized fuel hauler or water draw-off service.
• Inspect fill cap, spill bucket, and manway covers for entry points.
• Document the water level, date of removal, and method used.
• If water keeps returning after removal, or you cannot explain where it came from, consider halting delivery until the source is identified.

3. High Product / Overfill Alarm

A high product alarm is your ATG’s automated version of a spill prevention warning. Federal regulations at 40 CFR 280.20(c)(1)(ii) require new UST systems to have overfill prevention equipment that does one of three things — not all of them: automatically shut off flow into the tank when it is no more than 95 percent full; alert the transfer operator when the tank is no more than 90 percent full by restricting flow into the tank or triggering a high-level alarm; or restrict flow 30 minutes before overfilling, alert the transfer operator with a high-level alarm one minute before overfilling, or shut off flow so that none of the fittings on top of the tank are exposed to product.

If this alarm fires during a delivery, the driver must stop pumping immediately. If it fires when no delivery is in progress, you may have a calibration issue, a stuck float, or — in rare cases — a sign of product migration from a neighboring tank through a compromised interstitial space.

Overfill prevention equipment must be inspected at least once every three years to verify that it is set to activate at the correct level and will activate when product reaches that level (40 CFR 280.35(a)(2)); some state programs require it more often. If your high product alarm triggered and the audible/visual overfill device did not activate, log it as an equipment failure and schedule inspection.

4. Sensor Out / Probe Out Alarm

Veeder-Root alarms labeled SENSOR OUT and PROBE OUT indicate a problem with the monitoring hardware itself. Veeder-Root describes Sensor Out as “the sensor setup was performed incorrectly or a sensor is disconnected or is not functioning properly,” and Probe Out as a “hardware failure — probe or interconnecting wiring to console.”

This alarm is frequently underestimated by operators because it doesn’t directly say “leak.” But consider the regulatory implication: if your interstitial sensor is offline, your release detection system is not functioning. Under 40 CFR 280.40(a) your release detection method must be installed, calibrated, operated and maintained so that it actually works, so a sensor that is out leaves that tank without compliant release detection until it is fixed. And under 40 CFR 280.50(c) an alarm indicating a release may have occurred must be reported within 24 hours unless the monitoring device is found to be defective and is immediately repaired, recalibrated or replaced and additional monitoring does not confirm the initial result.

Common sensor fault causes and fixes:

5. Sump Sensor Alarm / Dispenser Pan Alarm

A sump alarm means liquid has been detected in one of your containment sumps — either a submersible turbine pump (STP) sump, a dispenser sump, or a transition sump. This is one of the most frequently triggered and most frequently mishandled ATG alarms in fuel retail.

Not all sump alarms mean product is present. Rainwater intrusion through worn conduit seals is extremely common. However, you cannot assume it’s rainwater without investigation. A hydrocarbon fuel smell or a sheen on the water surface means product is present — a reportable condition in most states.

ATG troubleshooting steps for sump alarms:

1. Access the sump and visually inspect the liquid.
2. Smell for fuel odor. Use a photoionization detector (PID) if available.
3. Check the liquid color — water is clear; fuel mixtures will appear discolored or show a sheen.
4. If water only: pump out, identify and seal the entry point, document.
5. If fuel present: do not pump to ground. Contact your environmental consultant and state agency.

6. Delivery Needed / Low Product Alarm

This is an operational alarm rather than a compliance alarm, but it carries an indirect regulatory implication. Running tanks too low — below the probe’s measurable range — can cause the ATG to lose accurate inventory data, disrupting the monthly inventory reconciliation that 40 CFR 280.43(a) requires if you use inventory control as a release detection method.

Additionally, extremely low product levels can expose the submersible pump to dry-run conditions, causing equipment damage that eventually creates leak points. Set your low-product threshold at a level that provides adequate delivery lead time for your volume.

7. Tank Test Failed / In-Tank Test Failed

When the ATG runs its periodic static leak detection test (typically during overnight low-traffic periods) and the result exceeds the 0.2 gph threshold, it logs a test failed alarm. This is distinct from a continuous leak alarm — it means the scheduled 0.2 gallon-per-hour in-tank test did not pass.

A single failed test may result from testing conditions rather than an actual leak: temperature variance during the test period, product delivery too close to test time, or high traffic volume interfering with tank stabilization. However, a second consecutive failed test should be treated as a suspected release.

Under 40 CFR 280.50(c), monitoring results that indicate a release may have occurred must be reported to the implementing agency within 24 hours unless one of the exceptions in that paragraph applies. In practice, a failed tank test requires you to:

• Investigate the cause before resuming normal operations.
• Retest under the conditions your ATG manufacturer specifies for a valid in-tank test.
• Report to your state agency if the failed test cannot be explained and a retest also fails.

Documentation: Your First Line of Legal Defense

Every alarm event — regardless of how minor — should be logged. Under 40 CFR 280.45(b), the results of any sampling, testing, or monitoring must be kept for at least one year — except that the results of the annual operation test of your release detection equipment must be kept for three years, and tank tightness test results must be kept until the next test is conducted. A well-documented alarm response log demonstrates that your facility is operating in good faith and responding to system alerts as required.

Your alarm response log should capture:

• Date and time the alarm occurred
• Alarm type and affected tank/sensor
• Name of person who responded
• Findings from physical inspection
• Actions taken and by whom
• Date and method of alarm resolution
• Whether a state agency notification was made (and to whom)

Many Veeder-Root systems allow you to print or export alarm history reports directly from the console. Run these monthly and store them with your compliance records. If your system is connected to a remote monitoring service, confirm that alarm notifications are being received and acknowledged in documented form.

When to Call a Professional vs. Handle In-House

Not every ATG alarm requires an outside technician, but knowing the boundary is critical for both compliance and liability reasons.

Action Items: ATG Alarm Compliance Checklist

Use this checklist to assess and strengthen your ATG alarm response program:

• ☐ Confirm all Class C operators know how to identify an active ATG alarm on the console display — Class C operators must be trained to take appropriate action, including notifying appropriate authorities, in response to emergencies or alarms caused by spills or releases from a UST system (40 CFR 280.242(c)).
• ☐ Create or update your written alarm response procedure, specifying who to call, in what order, for each alarm category.
• ☐ Verify your ATG is printing or logging alarm events and that records are being retained for the periods 40 CFR 280.45(b) requires — at least one year for monitoring results, three years for annual operation test results.
• ☐ Check sensor service schedules — since October 13, 2018, release detection equipment must be operated and maintained, and its electronic and mechanical components tested for proper operation at least annually, in accordance with the manufacturer’s instructions or a nationally recognized code of practice (40 CFR 280.40(a)(3)).
• ☐ Know your state’s 24-hour reporting number — post it at the ATG console and in your employee break room.
• ☐ Schedule your annual line leak detector test if you haven’t completed one in the past 12 months (required under 40 CFR 280.44).
• ☐ Review your last 90 days of ATG alarm history — recurring alarms on the same sensor often indicate equipment aging or a developing problem.
• ☐ Confirm your ATG technician is certified in your state — most states require UST contractor licensing for probe and sensor work.

ATG troubleshooting isn’t just about fixing equipment — it’s about protecting your license to operate. A single unaddressed leak alarm that results in a confirmed release can trigger remediation costs in the hundreds of thousands of dollars and years of regulatory oversight. The alarm is the system working. Your job is to make sure the human response works just as well.

Sources

Figures and citations in this article were checked against the following primary sources on 2026-09-07.

• 40 CFR 280.20 — performance standards for new UST systems (spill and overfill prevention)
• 40 CFR 280.35 — periodic testing of spill and overfill prevention equipment
• 40 CFR 280.40 — general requirements for release detection (annual operation testing)
• 40 CFR 280.43 — methods of release detection for tanks
• 40 CFR 280.44 — methods of release detection for piping
• 40 CFR 280.45 — release detection recordkeeping
• 40 CFR 280.50 — reporting of suspected releases
• 40 CFR 280.242 — operator training requirements
• 40 CFR 280.244 — operator retraining
• Veeder-Root, TLS System Warnings & Alarms, Manual No. 577014-243
• Veeder-Root, Monitoring Well Vapor Sensor Specifications (577013-750-21)
• Veeder-Root, Obsoleted Product Notifications (TLS-350 end of sale)
• 40 CFR 19.4 — inflation-adjusted civil penalty amounts
• Phase 3 reviewer brief (basis for removing unsourced figures)