UST Release Detection and Inventory Reconciliation
You are inspecting a gasoline station with two 10,000-gallon single-wall steel tanks installed in 1988. Tank 1 is equipped with automatic tank gauging (ATG) and a manual inventory system; Tank 2 has only manual inventory and a tightness-test record from four years ago. Over the past three months, Tank 1's inventory reconciliation shows a cumulative variance of 1.9 percent of throughput, and the ATG has logged three 'in-tank leak test fail' alarms in the same period, each cleared by the operator as a 'sensor glitch.' The station owner says the ATG was calibrated last year and that the alarms are nuisance trips. A delivery of 8,000 gallons was just made to Tank 1, and the operator wants to resume dispensing.
1. Evaluate whether Tank 1's release detection is compliant and what the alarms mean.
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Tank 1 is not in compliance. Three failed in-tank leak tests in three months, plus a 1.9 percent cumulative inventory variance, are not consistent with a properly functioning release detection system. The ATG alarm is a release detection result, not a nuisance to be cleared; repeatedly clearing alarms without investigation defeats the method. The operator must investigate the alarms, check the ATG calibration and probe function, and perform a confirmatory test. Until the cause is resolved, the tank should be treated as suspect. The judgment point is that inventory variance and repeated alarms together are a pattern that requires action, not a single data point to explain away.
2. What are the compliance problems with Tank 2 and the overall site?
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Tank 2 has no approved release detection method beyond a tightness test from four years ago; a periodic tightness test is not continuous release detection and does not meet the ongoing requirement for a tank of that age and configuration. The site also appears to lack corrosion protection documentation for single-wall steel tanks of that vintage. The correct response is to require an approved release detection method for Tank 2, obtain and review the tightness test and corrosion protection records, and document the deficiencies. The judgment point is that each tank must independently satisfy release detection, and a single old test record does not cover the ongoing obligation.
3. The operator wants to resume dispensing after the delivery. What should you require before product is dispensed?
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Require that the ATG alarms be investigated and resolved, that the inventory variance be reconciled, and that a confirmatory release detection test be performed on Tank 1. Do not allow dispensing to continue on the assumption that the alarms are glitches. If a release is suspected, follow the jurisdiction's reporting and investigation procedures before resuming operation. Document the delivery, the alarm history, and the corrective actions. The judgment point is that resuming dispensing is a decision that must be supported by resolved release detection results, not by the owner's assurance.