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Issue Date: November 22, 1995
Revision Date: March 20, 2003
USTest, Inc.
UST 2000/LL
VOLUMETRIC TANK TIGHTNESS TEST
METHOD (UNDERFILL)
USTest, Inc., no longer
supports the use of this method *
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Certification |
Leak rate of 0.1
gph with PD = 98.12% and PFA = 1.88%. |
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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. |
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Applicability |
Gasoline, diesel,
aviation fuel, water, kerosene.
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Tank Capacity |
Maximum of 15,000
gallons.
Tank must be minimum 15% full.
There must be at least 20 inches and not more than 67 inches of product in
the tank. |
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Waiting Time |
Ranges from 3 to
12 hours between delivery and testing.
Testing may begin when the rate of product temperature change does not
exceed 0.1 degree F per hour.
There must be no dispensing or delivery during waiting time.
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Test Period |
Minimum of 2
hours.
Test data are acquired and recorded by system’s computer, which does a
regression analysis to determine the leak rate.
An ultrasonic device is used to measure changes in product level.
There must be no dispensing or delivery during test. |
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Temperature |
Average for
product is determined from the measurement of the change in the speed of
sound. |
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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.
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Calibration |
Temperature
sensors and probes must be checked annually and, if necessary, calibrated in
accordance with manufacturer’s instructions. |
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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.
* USTest Inc. has requested removal of the 2000/LL equipment from the NWGLDE
List and discourages the use of this method due to software security and
data integrity problems. |
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USTest, Inc.
c/o Dubois, Bryant, Campbell & Schwartz
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Evaluator:
Ken Wilcox Associates
Tel:
(816) 443-2494
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P.O Box 909
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Date
of Evaluation: 06/09/94
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Austin, TX 78767
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Tel: 512-457-8000 |
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