| 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 pipeline system
should not be declared tight when tracer chemical greater than the
background level is detected outside of
the pipeline. |
| Applicability |
Gasoline, diesel,
aviation fuel, fuel oil #4, waste oil.
|
| Pipeline
Capacity |
Not limited by
capacity. |
| Waiting
Time |
Ranges from 7 to
30 days after tracer is added to tank without support of on-site simulation.
The waiting period may be adjusted below this range when supported by
on-site leak simulations performed as described below.
For very large pipeline systems, several days or weeks may be required to
circulate tracer-labeled product through all parts of the pipeline.
Waiting time begins after tracer has reached all portions of the pipeline
being tested. |
|
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.
Tracer-labeled product must be circulated through the pipeline before test
period begins.
Pressurized pipeline must be brought up to operating pressure or operated
on a daily basis. |
| 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.
Pipeline must be accurately located to ensure that all pipeline surfaces
are 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. |
| 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 surrounding pipeline may limit effectiveness of test method
(e.g. when applied to pipelines containing water-miscible products or
products whose specific gravity is greater than 1). |
