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Leak Detection

Monthly Release Detection for Tanks.

Tanks must have one form of monthly release detection listed below:

Automatic Tank Gauging (ATG)

Probes in the tank are connected to a console containing electronics that monitor product levels. Precise product level readings are made in frequent intervals and a computer processes information and determines if preset conditions have been exceeded.

Statistical Inventory Reconciliation (SIR)

This method requires the operator to stick tank every day that it is in operation and send a record to a SIR analyst who performs special statistical analysis with a computer.

Some SIR analysis can be performed in house if an approved method is used. 

Secondary Containment and Interstitial Monitoring 

Secondary containment consist of a double wall tank, double wall piping, under dispenser sump, or tank top sump.  

Interstitial Monitoring is a method of continuous leak detection which uses a monitoring device between the walls of a double-walled tank. 

Manual Tank Gauging

Manual Tank Gauging maybe used on tanks 2000 gallons or less.  However tanks between 1001-2000 gallons must also conduct tank tightness testing.

Tank Tightness Testing

Leak Detection For Piping

There are two types of piping pressurized and suction.

Pressurized Piping

Pressurized Piping uses a pump submerged in the product and maintains a positive pressure on the product lines even when product is not being dispensed.

Pressurized piping must have two forms of release detection:

  1. Monthly (small leaks) requirements can be met by conducting an annual leak detection test using one of the following:
    1. Tank Leak Detection Methods (Statistical Inventory Reconciliation, Secondary Containment and Interstitial Monitoring
    2. Annual Line Tightness Test 
    3. Electronic Line Leak Detection
  2. Catastrophic (large leaks) requirements can be met by making sure every line has the appropriate Electronic or Mechanical Leak detector.  The mechanical line leak detectors will need to be tested annually.  Electronic can be tested annually or once every month.  See Pressurized Piping 

Suction Piping

Suction Piping has a motor and pulleys inside the dispenser that pulls the fuel to the dispenser.

A three year Line Tightness test is required for suction piping if piping has a check valve at the tank.  

Motor Fuel Dispensers and Spill Buckets

  • Motor fuel dispensers installed after July 24, 2007 must be interstitially monitored and secondarily contained.  All dispensers must be inspected quarterly for seeps and drips and results recorded on the Quarterly Dispenser Inspection Log (CN-1287)
  • Spill buckets must be inspected monthly and dispensers must be inspected quarterly and a record made of those inspections. These records must be maintained showing the last 12 months of these inspections on the Monthly Spill Bucket Inspection Log (CN-1286)

For a more detailed descriptions of release detection please refer to the Tennessee UST Owner Compliance Manual chapter 10  for tanks and piping, Chapter 7 for Spill Protection, or one of the technical documents above.