| Certification |
Leak rate of 0.1
gph with PD = 99.99% and PFA = 0.005%. |
| Leak
Threshold |
0.05 gph.
A tank system should not be declared tight if the test result indicates a
loss or gain that equals or exceeds this threshold. |
| Applicability |
Gasoline, diesel,
aviation fuel, fuel oil #4. |
| Tank
Capacity |
Maximum of 18,000
gallons.
Tank must be between 11 and 95% full. |
| Waiting
Time |
Minimum of 6
hours between delivery and testing.
None between dispensing and testing.
There must be no delivery during waiting time. |
| Test
Period |
Minimum of 3
hours.
Test data are acquired and recorded by system's computer.
Leak rate is calculated from average of subsets of all collected
data.
There must be no dispensing or delivery during test. |
| Temperature |
Average for
product is determined by temperature sensor probes.
A minimum 12 inches of product must be present for the temperature probes
to operate properly. |
| Groundwater |
Depth to
groundwater in tank excavation backfill must be determined.
If groundwater is above bottom of tank, product level must be adjusted
during test to provide a minimum net pressure of 1 psi at bottom of tank
during test. |
| Calibration |
Temperature
probes and floats must be checked for proper operation prior to each test. |
| Comments |
Not evaluated
using manifolded tank systems.
Tests only portion of tank containing product.
As product level is lowered, leak rate in a leaking tank decreases (due to
lower head pressure).
Consistent testing at low levels could allow a leak to remain
undetected.
EPA leak detection regulations require testing of the portion of the tank
system which routinely contains product. |
