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Issue Date: November 22, 1995
Revision Date: March 20, 2003
USTest, Inc.
UST 2000/P
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 = 99.9% and PFA = 0.1% for tanks up to 15,000 gallons.
Leak rate of 0.1 gph with PD = 99.7% and PFA = 0.3% for tanks from 15,000
gallons up to 45,000 gallons. |
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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
Between 20,000 gallons and 45,000 gallons.
Tank must be minimum 78.6% full. |
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Waiting Time |
Minimum for tanks
up to 45,000 gallons must be determined from the manufacturer's chart of
“Wait Time versus Tank Volume." This chart must be included in the
tank test report.
There must be no dispensing or delivery during waiting time.
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Test Period |
Minimum for tanks
less than 10,000 gallons is one hour.
Minimum for tanks from 10,000 to 45,000 gallons is determined from the
manufacturer's chart of “Differential Volume versus Test Duration."
Line labeled PD = 99.9% must be used. This chart must be included in the
tank test report. Test data are acquired and recorded by system’s computer,
which does a regression analysis to determine the leak rate. 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 the tank during test.
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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/P 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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Evaluators: Midwest Research Institute
Tel: (816) 753-7600
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P.O Box 909
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Ken
Wilcox Associates
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Austin, TX 78767
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Tel: (816) 443-2494
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Tel: 512-457-8000 |
Dates of Evaluation: 12/05/90 (1000-10,000 gallons), 08/04/92 (10,000-45000 gallons)
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