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Issue Date: November 22, 1995
Revision Date: September 22, 2009
Tanknology
Computerized
VPLT Testing System
VOLUMETRIC TANK TIGHTNESS TEST
METHOD (UNDERFILL)
| Certification |
Leak rate of 0.1
gph with PD = 99.9% and PFA = 0.1%. |
| 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, waste oil. |
| Tank
Capacity |
Maximum of 18,000
gallons. Tank must contain minimum 24 inches of product. |
| Waiting
Time |
Must be long
enough between delivery and testing to ensure a temperature change of less
than 0.09 degrees F per hour, typically a minimum of 2 hours.
None between dispensing and testing. There must be no delivery during
waiting time. |
| Test
Period |
Minimum of 2
hours.
Test data are acquired and recorded by system's computer.
Leak rate is calculated from average over data window.
There must be no dispensing or delivery during test. |
| Temperature |
Average for
product is typically determined by 5 thermistors.
A minimum of 1 thermistor is required. |
| Groundwater |
Depth to
groundwater in tank excavation backfill must be determined.
If groundwater is above bottom of tank, product level must be adjusted to
provide a minimum net pressure of 1 psi at bottom of tank during test. |
| Calibration |
Thermistors must
be checked annually and, if necessary, calibrated in accordance with
manufacturer's instructions. |
| 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. |
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Tanknology
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Evaluator:
Ken Wilcox Associates
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11000 North MoPac Expressway, Suite 500
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Tel:
(816) 443-2494
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Austin, TX 78759
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Date of
Evaluation:
02/15/93
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Tel: (800) 800-4633
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