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United StatesEnvironmental Protection Agency
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New JerseyDepartment of Environmental Protection (DEP)
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DEP Site Remediation Program August 1996
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Manual Tank Gauging
For Small Underground Storage Tanks
Manual Tank Gauging
State of New Jersey
Christine Todd Whitman
Governor
New Jersey Department of Environmental Protection
Robert C. Shinn, Jr.
Commissioner
August 1996
MAIL REQUESTS FOR COPIES TO:
New Jersey Department of Environmental Protection
Site Remediation Program
UST Brochure Request-Manual Tank Gauging
CN 433
Trenton, New Jersey 08625
FOR MORE INFORMATION CALL: 609/292-8761
Why You Should Read This Booklet
Federal and New Jersey laws require underground storage
tanks (USTs) to have leak detection. A lot of attention has been focused
on large gasoline tanks, but it is also important to detect leaks from
tanks 2,000 gallons or smaller, which often contain used oil.
If your USTs do not have leak detection, you will not
be in compliance with federal and state laws and may be subject to penalties.
Leak detection violations can also keep you from getting legally required
insurance coverage and reimbursement for cleanup costs. Without leak
detection, you constantly risk discovering a leak only after it becomes
a major financial burden for yourself and an environmental problem for
everyone.
Manual tank gauging is a leak detection method that
can be used only on tanks 2,000 gallons or smaller. If this method
is appropriate for any of your USTs, this booklet can help you make
sure you do manual tank gauging correctly.
If you need information on New Jersey leak detection
requirements and the various methods of leak detection available to
you, see "Straight Talk On Tanks." Call the DEP at 609 292-8761, and
order this free publication by name.
How Does Manual Tank Gauging Work?
This booklet helps you use manual tank gauging
to meet federal regulatory leak detection requirements by
showing you how to do three important tasks:
• Good sticking
• Good math
• Good recordkeeping
Without these three, you may fail to meet
the leak detection requirements. Steps 1 through 5 on the
following pages show you how to perform manual tank gauging
correctly.
Basically, manual tank gauging involves taking
the tank out of service every week for 36 hours or more
while you measure the tank's contents to see if changes in
the tank's volume indicate a possible leak.
Manual tank gauging can be used only on
tanks 2,000 gallons or smaller. Be sure you read about
several important restrictions on the use of manual tank gauging
that are described on the next page.
To use manual tank gauging correctly,
follow Steps 1–5 starting on page 5.
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Please
note these important restrictions on the use of manual tank
gauging:
• Manual tank gauging can be used only
on tanks 2,000 gallons or smaller.
• Tanks 1,000 gallons or smaller can
use this method alone.
• Tanks from 1,001 to 2,000 gallons
can use manual tank gauging only when it is combined with
periodic tank tightness testing. The combined method
of manual tank gauging and tank tightness testing is a TEMPORARY
leak detection method. You can use manual tank gauging
as leak detection on tanks that have NOT yet been upgraded
with corrosion protection and spill/overfill devices (upgrade
or tank closure must occur by December, 1998). You can continue
to use manual tank gauging as leak detection only for 10 years
after upgrading an old tank with corrosion protection and
spill/overfill devices. You can also use manual tank gauging
as leak detection for 10 years after installing a new tank
that has corrosion protection and spill/overfill devices.
After the 10-year period, you must use a monthly monitoring
method, such as groundwater monitoring or interstitial monitoring.
Before December 1998, these tanks need
tightness testing every year.
• The use of manual tank gauging does
not meet your tank system's leak detection requirements for
piping. Pressurized and some suction piping must use other
methods of leak detection, such as interstitial monitoring.
(See "Straight Talk On Tanks.")
If you don't pay careful attention to
these restrictions, you will fail to meet the leak detection
requirements.
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Do You Have The Right Equipment?
Gauge Stick Or Other Gauges
The gauge stick used to measure the
depth of liquid in an underground tank must be marked
or notched to the _ inch, starting with zero at the bottom
end. Check your stick to be sure the end has not been
worn or cut off and that the stick is not warped. The
stick should be made of non-sparking material, such as
wood, and varnished to minimize the creeping of fuel above
the actual fuel level in the tank. Instead of using a
gauge stick, you may use a mechanical or electronic tank
level monitor. Whatever measuring device you use must
be capable of measuring the level of product over the
full range of the tank's height to the nearest _ inch.
Forms
The instructions in this booklet
are keyed to the "Manual Tank Gauging Record" form. You
will find a filled-in sample of this form on the last
page of this booklet. This sample is on a perforated page,
so tear it out and refer to it while you read through
the directions that are keyed alphabetically to it. Also,
near the back of the booklet, you will find blank "masters"
you can copy repeatedly to provide forms for use in your
recordkeeping. If the "Manual Tank Gauging Record"
is filled out according to the instructions in this booklet,
you will be in compliance with state and federal regulations
for manual tank gauging.
Tank Chart
A tank chart is a table that converts
the number of inches of liquid in the tank into the number
of gallons. You need a tank chart that exactly matches
your storage tank (tank manufacturers usually provide
charts for their tanks). If you have more than one tank,
you will need a chart for each tank unless the tanks are
identical. The tank chart must show conversion to gallons
for each _ inch stick reading. If your tank chart does
not convert each _ inch reading into gallons, contact
the tank manufacturer, or, if you have a steel tank, the
Steel Tank Association (708 438-8265), to get an appropriate
chart.
You always need to convert inches
into gallons in order to fill out the form correctly and
to do the necessary math. To convert inches into gallons,
find your stick's reading to the nearest _ inch on the
tank chart, then simply read across to the gallons column
to find the number of gallons. If you cannot get a tank
chart showing conversion to gallons for each _ inch reading,
you must do the additional math explained on page 8.
Step 1–Find The Right Testing Period
Once each week
you must take your tank out of service for a testing period. The length
of the testing period depends on the size of your tank and whether you
are using manual tank gauging alone or in combination with tank tightness
testing.
Circle
your tank size and test duration in the table so you will know
which you are using. To identify the appropriate testing period,
use the sample form found on the last page of this booklet and
locate your tank on the table in the upper left corner of the
sample form (see the section labeled "A"). You know which testing
period you need to use every week by looking at the number
in the "Minimum Duration Of Test" column next to the box that
matches a description of your tank. With tanks of 551 to 1,000
gallons, you can choose a shorter test time (36 hours) with
tightness testing or a longer test time (44 or 58 hours,
depending on tank diameter) without tightness testing.
During the test period
the tank must remain out of service so that nothing is put into the
tank and nothing is taken out of it.
Step 2–Measure The Tank's Contents
Every week,
you must take liquid level measurements twice before and twice after
each out-of-service testing period.
Fill
in the identifying information at the top of the "Manual Tank
Gauging Record" form. You need a separate form for each tank using
manual tank gauging.
Take
your first stick reading using "good sticking practices" noted
in the box on the right. Enter your reading in the column labeled
"First Initial Stick Reading."
Wipe
the stick dry with a rag and take a second stick reading as you
did before. Enter the second reading in the column labeled
"Second Initial Stick Reading."
After the readings are
taken, the tank opening should be closed so that no liquid can be added
or removed from the tank.
When
the out-of-service testing period is over, take two more stick
readings in the same way you took the first two readings. Enter
the ending readings in the columns labeled "First End Stick Reading"
and "Second End Stick Reading".
Step 3–Do Some Math
Every week at the end of the test
period, you must record some math calculations.
Average
the two initial stick readings to the nearest _ inch.
Enter the result in the "Average Initial Reading"
column.
The
average stick reading of the tank's contents will be
in inches. You always need to convert inches
into gallons in order to fill out the form completely
and to calculate the change in the tank volume. Find
your stick's reading on the tank chart to the nearest
_ inch, then read across to the gallons column to find
the number of gallons. Enter the result in the "Initial
Gallons" column.
Your
tank chart should have direct conversions from _ inch
stick readings to gallons. If you cannot get a tank
chart with _ inch conversions, do the additional math
explained on page 8.
Average
the two end stick readings to the nearest _ inch. Enter
the result in the "Average End Reading" column.
Convert
the average stick reading from inches into gallons (as
you did in item "G" above) and enter the result in
the "End Gallons" column.
Subtract the "End Gallons" column from the "Initial
Gallons" column. Enter the result in the column labeled
"Change In Tank Volume."
Step 4–Find The Right Test Standards
The
weekly and monthly test standards depend
on tank size and whether you are using manual tank gauging
alone or in combination with tank tightness testing.
To find your tank's weekly and monthly test standards,
locate your tank on the table in the upper left corner
of the sample manual tank gauging record (see the section
labeled "K"). You know which test standards apply to
your tank by looking at the gallon numbers in the "Weekly
Standard" and "Monthly Standard" columns next to your
tank.
Circle
the weekly and monthly test standards in the table that
apply to your tank so you will know which standards
your tank must meet.
Step 5–Compare Your Measurements With Test
Standards
You must compare your calculation of "Change In Tank
Volume" to the weekly and monthly test standards for your tank.
Every
week, compare your "Change In Tank Volume" number to the weekly
test standard. For the purpose of this comparison, consider all
numbers to be positive (for example, a -16 would become a +16).
If your "Change In Tank Volume" number is not larger than the
weekly test standard, circle YES in the "Tank Passes Test" column.
If your "Change In Tank Volume" number is larger than the weekly
test standard, circle NO. If you circle NO, you have a "suspected
release" (see section "N" below).
Once
a month, add up the 4 weekly "Change In Tank Volume" numbers:
this time pay careful attention to positive and negative numbers
to get an accurate total. For example, adding +4 and +3 and -2
and -1 should equal +4. After you have the sum of the 4 weekly
tests, divide by 4 to get the monthly test average. Enter the
result at the bottom of the "Change In Tank Volume" column.
Compare your monthly test average to
the monthly test standard for your tank. For the purpose of this
comparison, again consider all numbers to be positive (for example,
a -16 would become a +16). If your "Change In Tank Volume" number
is not larger than the monthly test standard, circle YES in the
"Tank Passes Test" column. If your monthly average "Change In
Tank Volume" is larger than the monthly test standard, circle
NO. If you circle NO, you have a "suspected release" (see section
"N" below).
If
you have a "suspected release", you have seven days to conduct
an investigation to confirm or disprove that your tank is leaking.
Once your investigation has been completed, if you have confirmed
that your tank is leaking, then you must notify DEP immediately
by calling the Environmental Action Hotline (609 292-7172). After
calling, you must arrange to clean up the contamination from your
leak. To perform a proper cleanup (also called "corrective action"),
you must follow the Technical Requirements for Site Remediation
(N.J.A.C. 7:26E). Copies of N.J.A.C. 7:26E can be ordered from
the Office of Administrative Law at 609 588-6606. Within 120 days
of reporting your leak, you must also submit a remedial investigation
report to the DEP, describing all cleanup activities conducted
and results found.
Using Tank Charts Without _ Inch Conversions
If your tank chart does not list direct conversions
from inches to gallons for every _ inch, then you must do the additional
math described below every time you stick your tank.
The easiest way to explain this procedure is with an
example. Let's say you have a stick reading of 23_ inches and you need
to figure how many gallons are in your tank.
1. Look on your tank chart and find the
inch measurements that are just above and below your stick reading
and write down the number of gallons for these inch readings. Subtract
the gallon readings to find the difference between the two readings:
Chart reading at
24 inches: 325 gallons
Chart reading at
23 inches: 293 gallons
----------------------------------------------------------------------------
Difference:
32 gallons
2. Dividing 32 by 8 will give you the number
of gallons for each _ inch, which is 4 gallons. (Round off the number
to the nearest whole number.) Because your fraction is _, multiply
4 gallons by 3, which gives you 12 gallons as the volume represented
by _ inch.
CAUTION: The gallons represented by each
_ inch will vary from top to bottom of the tank and must be calculated
for each conversion.
3. Take the number of gallons you have just
calculated and add it to the inch reading just below your actual
stick reading:
Chart reading at
23 inches: 293 gallons
Gallons at _ inch:
+ 12 gallons
-----------------------------------------------------------------------------
Sum: 305
gallons
Thus, your stick reading of 23_ inches converts to
305 gallons.
NOTE: If your tank chart is in half or quarter
inches, you must still use this procedure so that your gallon readings
are accurate to _ inch.
After all of this math, you can see why it pays to
have the correct tank chart that indicates gallons for each _ inch.
MANUAL TANK GAUGING
RECORD Month _______________
Year _________
Tank Identification _____________________________
Person Completing Form _______________________
Circle your tank size,
test duration, and weekly/monthly standards in the table below:
Facility Name_____________________________________
|
Tank Size
|
Minimum Duration
Of Test
|
Weekly
Standard
(1 test)
|
Monthly Standard
(4-test average)
|
Compare your weekly readings and the monthly average of the 4
weekly readings with the standards shown in the table on the left.
If the calculated change exceeds the weekly standard, the UST
may be leaking. Also, the monthly average of the 4 weekly test
results must be compared to the monthly standard in the same way.
If either the weekly or monthly standards have been exceeded,
the UST may be leaking. Within 7 days, investigate to confirm
or disprove that your tank is leaking. If you confirm that your
tank is leaking, you must notify the DEP immediately by
calling the Environmental Action Hotline (609 292-7172). After
calling, you must arrange to clean up the contamination from your
leak. To perform a proper cleanup, you must follow the Technical
Requirements for Site Remediation (N.J.A.C. 7:26E). Copies of
N.J.A.C. 7:26E can be ordered from the Office of Administrative
Law at 609 588-6606. Within 120 days of reporting the leak, you
must also submit a remedial investigation report to the DEP, describing
all cleanup activities conducted and results found.
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up to 550 gallons
|
36 hours
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10 gallons
|
5 gallons
|
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551-1,000 gallons
(when tank diameter is 64")
|
44 hours
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9 gallons
|
4 gallons
|
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551-1,000 gallons
(when tank diameter is 48")
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58 hours
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12 gallons
|
6 gallons
|
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551-1,000 gallons (also requires
periodic tank tightness testing)
|
36 hours
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13 gallons
|
7 gallons
|
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1,001-2,000 gallons (also requires periodic tank
tightness testing)
|
36 hours
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26 gallons
|
13 gallons
|
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Start Test
(month, day,
and time)
|
First
Initial
Stick
Reading
|
Second
Initial
Stick
Reading
|
Average
Initial
Reading
|
Initial
Gallons (convert inches to gallons)
[a]
|
End Test
(month, day, and time)
|
First
End
Stick
Reading
|
Second
End
Stick
Reading
|
Average
End
Reading
|
End
Gallons (convert inches to gallons)
[b]
|
Change
In Tank
Volume
In Gallons
+ or (—)
[a—b]
|
Tank
Passes Test
(circle
YES or NO)
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Date:
Time: AM/PM
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Date:
Time: AM/PM
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Y N
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Date:
Time: AM/PM
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Date:
Time: AM/PM
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Y N
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Date:
Time: AM/PM
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Date:
Time: AM/PM
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Y N
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Date:
Time: AM/PM
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Date:
Time: AM/PM
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Y N
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KEEP
THIS PIECE OF PAPER ON FILE
|
To see how close you are to the monthly standard,
divide the sum of the 4 weekly readings by 4 and enter result
here >
|
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Y N
|
MANUAL TANK GAUGING
RECORD Month _______________
Year _________
Tank Identification _____________________________
Person Completing Form _______________________
Circle your tank size,
test duration, and weekly/monthly standards in the table below:
Facility Name_____________________________________
|
Tank Size
|
Minimum Duration
Of Test
|
Weekly
Standard
(1 test)
|
Monthly Standard
(4-test average)
|
Compare your weekly readings and the monthly average of the 4
weekly readings with the standards shown in the table on the left.
If the calculated change exceeds the weekly standard, the UST
may be leaking. Also, the monthly average of the 4 weekly test
results must be compared to the monthly standard in the same way.
If either the weekly or monthly standards have been exceeded,
the UST may be leaking. Within 7 days, investigate to confirm
or disprove that your tank is leaking. If you confirm that your
tank is leaking, you must notify the DEP immediately by
calling the Environmental Action Hotline (609 292-7172). After
calling, you must arrange to clean up the contamination from your
leak. To perform a proper cleanup, you must follow the Technical
Requirements for Site Remediation (N.J.A.C. 7:26E). Copies of
N.J.A.C. 7:26E can be ordered from the Office of Administrative
Law at 609 588-6606. Within 120 days of reporting the leak, you
must also submit a remedial investigation report to the DEP, describing
all cleanup activities conducted and results found.
|
|
up to 550 gallons
|
36 hours
|
10 gallons
|
5 gallons
|
|
|
551-1,000 gallons
(when tank diameter is 64")
|
44 hours
|
9 gallons
|
4 gallons
|
|
|
551-1,000 gallons
(when tank diameter is 48")
|
58 hours
|
12 gallons
|
6 gallons
|
|
|
551-1,000 gallons (also requires
periodic tank tightness testing)
|
36 hours
|
13 gallons
|
7 gallons
|
|
|
1,001-2,000 gallons (also requires periodic tank
tightness testing)
|
36 hours
|
26 gallons
|
13 gallons
|
|
|
Start Test
(month, day,
and time)
|
First
Initial
Stick
Reading
|
Second
Initial
Stick
Reading
|
Average
Initial
Reading
|
Initial
Gallons (convert inches to gallons)
[a]
|
End Test
(month, day, and time)
|
First
End
Stick
Reading
|
Second
End
Stick
Reading
|
Average
End
Reading
|
End
Gallons (convert inches to gallons)
[b]
|
Change
In Tank
Volume
In Gallons
+ or (—)
[a—b]
|
Tank
Passes Test
(circle
YES or NO)
|
|
Date:
Time: AM/PM
|
|
|
|
|
Date:
Time: AM/PM
|
|
|
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Y N
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Date:
Time: AM/PM
|
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Date:
Time: AM/PM
|
|
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Y N
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Date:
Time: AM/PM
|
|
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|
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Date:
Time: AM/PM
|
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Y N
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Date:
Time: AM/PM
|
|
|
|
|
Date:
Time: AM/PM
|
|
|
|
|
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Y N
|
|
KEEP
THIS PIECE OF PAPER ON FILE
|
To see how close you are to the monthly standard,
divide the sum of the 4 weekly readings by 4 and enter result
here >
|
|
Y N
|
MANUAL TANK GAUGING
RECORD Month _______________
Year _________
Tank Identification _____________________________
Person Completing Form _______________________
Circle your tank size,
test duration, and weekly/monthly standards in the table below:
Facility Name_____________________________________
|
Tank Size
|
Minimum Duration
Of Test
|
Weekly
Standard
(1 test)
|
Monthly Standard
(4-test average)
|
Compare your weekly readings and the monthly average of the 4
weekly readings with the standards shown in the table on the left.
If the calculated change exceeds the weekly standard, the UST
may be leaking. Also, the monthly average of the 4 weekly test
results must be compared to the monthly standard in the same way.
If either the weekly or monthly standards have been exceeded,
the UST may be leaking. Within 7 days, investigate to confirm
or disprove that your tank is leaking. If you confirm that your
tank is leaking, you must notify the DEP immediately by
calling the Environmental Action Hotline (609 292-7172). After
calling, you must arrange to clean up the contamination from your
leak. To perform a proper cleanup, you must follow the Technical
Requirements for Site Remediation (N.J.A.C. 7:26E). Copies of
N.J.A.C. 7:26E can be ordered from the Office of Administrative
Law at (609) 588-6606. Within 120 days of reporting the leak,
you must also submit a remedial investigation report to the DEP,
describing all cleanup activities conducted and results found.
|
|
up to 550 gallons
|
36 hours
|
10 gallons
|
5 gallons
|
|
|
551-1,000 gallons
(when tank diameter is 64")
|
44 hours
|
9 gallons
|
4 gallons
|
|
|
551-1,000 gallons
(when tank diameter is 48")
|
58 hours
|
12 gallons
|
6 gallons
|
|
|
551-1,000 gallons (also requires
periodic tank tightness testing)
|
36 hours
|
13 gallons
|
7 gallons
|
|
|
1,001-2,000 gallons (also requires periodic tank
tightness testing)
|
36 hours
|
26 gallons
|
13 gallons
|
|
|
Start Test
(month, day,
and time)
|
First
Initial
Stick
Reading
|
Second
Initial
Stick
Reading
|
Average
Initial
Reading
|
Initial
Gallons (convert inches to gallons)
[a]
|
End Test
(month, day, and time)
|
First
End
Stick
Reading
|
Second
End
Stick
Reading
|
Average
End
Reading
|
End
Gallons (convert inches to gallons)
[b]
|
Change
In Tank
Volume
In Gallons
+ or (—)
[a—b]
|
Tank
Passes Test
(circle
YES or NO)
|
|
Date:
Time: AM/PM
|
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|
|
|
Date:
Time: AM/PM
|
|
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|
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|
Y N
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|
Date:
Time: AM/PM
|
|
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|
|
Date:
Time: AM/PM
|
|
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Y N
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|
Date:
Time: AM/PM
|
|
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Date:
Time: AM/PM
|
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Y N
|
|
Date:
Time: AM/PM
|
|
|
|
|
Date:
Time: AM/PM
|
|
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|
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Y N
|
|
KEEP
THIS PIECE OF PAPER ON FILE
|
To see how close you are to the monthly standard,
divide the sum of the 4 weekly readings by 4 and enter result
here >
|
|
Y N
|
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