| Certification |
Leak rate of 0.1
gph with PD = 100% and PFA = 0%.
Leak rate of 0.005 gph with PD = 97% and PFA = 2.9%. |
| Leak
Threshold |
A tank system
should not be declared tight when tracer chemical greater than the
background level is detected outside of the tank system. |
| Applicability |
Gasoline, diesel,
aviation fuel, fuel oil #4, waste oil.
|
| Tank
Capacity |
Not limited by
capacity. |
| Waiting
Time |
Ranges from 7 to
30 days after tracer is added to tank without support of on-site leak
simulation.
The waiting period may be adjusted below this range when supported by
on-site leak simulations performed as described below. |
|
Leak Simulations |
The release of
surrogate tracer into the soil or backfill to evaluate the migration of a
tracer and the sensitivity of the test under on-site sub-surface conditions.
Sub-surface conditions throughout the test area must be at least as
favorable as those at the leak simulations location in order to use the
results. This requirement may be satisfied by sampling the backfill
material, and/or making flow/vacuum measurements from the sampling probes. |
| Tracer
Dosage |
Dosage of tracer
is based on tank size, product volume in tank, and frequency and volume of
tank refills according to manufacturer's recommendations. |
| Permeability |
Soil permeability
must readily allow tracer movement through the tank excavation backfill
(greater than 1 Darcy). |
| Probe |
Radius of
influence of each tracer sampling probe is maximum 10 feet.
All tank surfaces must be within the zone of influence of a sampling
probe.
Probes must be installed per manufacturer's guidelines.
Horizontal sampling probes may be installed in manufactured backfill during
the installation of a new UST system. These probes must be installed per
manufacturer’s guidelines. |
| Groundwater |
Depth to
groundwater in tank excavation backfill must be determined.
For test method to detect a release of tracer chemical below groundwater,
the hydrostatic pressure of product in the tank must exceed the
hydrostatic pressure of groundwater during test.
To accomplish this, product level must be maintained at least 6 inches
above groundwater for a minimum 17 hours during the first three days
following addition of tracer to the tank.
At the discretion of the regulatory agency, water ingress measuring
devices may be used to supplement test method in high groundwater
conditions. |
| Comments |
The tester may
determine that pre or post testing is needed to establish the background
level of tracer in the soil.
The presence of a
layer of water saturated soil, that is also frozen, above the location where
a leak may exist, may inhibit the effectiveness of the method by impeding
the transport of the tracer labeled product into the unsaturated zone.
Groundwater above bottom of tank may limit effectiveness of test method
(e.g. when applied to tanks containing water-miscible products or products
whose specific gravity is greater than 1). |
