Certification

Leak rate of 0.005 gph as vapor with P_D = 100% and P_FA = 0%.

Leak Threshold

A tank system should not be declared tight when brine is observed in the primary containment.

Applicability

Method tests the primary containment of newly installed secondarily contained tanks. It does not test single-wall, portions of the tank that are not exposed to the brine solution such as tank bungs and manway penetrations. The primary component of the system under test must be dry, containing no liquid, except that it may contain up to 1 inch of residual ballast water if a dyed brine solution is used. The interstice must be liquid filled.

Tank Capacity

Not limited by capacity.

Test Period

Following the pre-test waiting time, normal test duration operationally in the field is 1 minute for each 5 feet of leak point target area (up to 4 feet wide), and is less than 60 minutes for most containers. The test duration can vary depending on the condition of the tank surface. If the tank surface is clean and free of any water, the test duration could be shorter. If the inside of the tank is dirty, contains some gravel and has up to 1 inch of ballast water, it is possible that the test duration would be longer. The assessment of the tank condition is determined by the trained technician that is operating the iotaVision™ method. Once the tank condition is determined, an appropriate test duration is implemented.

Waiting Time

After the brine level is raised to a minimum of 3 inches above the primary tank, a minimum 30 minutes of pre-test waiting time to allow brine solution to collect in the low point of the tank where it may be visually observed.

Dosage

The interstice must be completely filled with colored or clear brine.

Sampling Points

Tank top access must be sufficient to allow the entry of the remote observation vehicle. 

Groundwater

Groundwater level is not determined and does not impact the test.

Detector

Colored or colorless brine is observed visually via a remote inspection vehicle inserted into the tank.

Calibration

Not applicable.

Comments

This method allows for the detecting of the clear brine solution or a dyed brine solution ingress into the primary space of a double walled tank at any point that can be observed.
When a dyed brine that has a contrasting color, when compared to the tank surface, is used to fill the interstice, there can be up to 1 inch of water present at the bottom of the tank at the beginning of the pre-soak test period.
This method is mainly used to test newly installed double walled tanks that have an interstitial space that is filled with a colored brine solution. These newly installed tanks do not have product present inside the primary area of the tank.
CGRS prohibits the use of this test method in a tank that has contained petroleum product at any time without specific written approval from the CGRS director of health and safety.