1

Task Order 3003 – General Technical and Programmatic Support for Regulatory 

Development

Technical Directive Number 9 

Task 2, Subtask b – Release Detection Research

Summary of Release Detection Research

May 27, 2009

Background

This report includes summaries of the following five research tasks related to release 

detection:

 The degree to which currently available release detection equipment can exceed 

federal UST performance requirements;

 Costs for equipment that meets or exceeds federal standards;

 State release detection requirements that are more stringent than federal 

requirements;

 Costs of interstitial monitoring; and,

 Costs for periodic integrity testing of the interstitial space for secondarilycontained UST systems.

Eight appendices are included as Excel worksheets:

 Appendix A: Release Detection System Capabilities

 Appendix B: Release Detection Performance and Costs

 Appendix C: Summary of State Federal Language Incorporation

 Appendix D: Summarized State Regulation Compliance with Federal Regulations

 Appendix E: Additional State Regulations

 Appendix F: State Regulation Sources

 Appendix G: State Requirements

 Appendix H: Interstitial Monitoring Costs

 Appendix I: Integrity Testing Costs

Release Detection Equipment Capabilities Analysis

Methodology

E

2

Inc. analyzed the leak rate, probability of detection (Pd), and probability of false alarm 

(Pfa) capabilities for UST leak detection equipment included in the National Work Group 

on Leak Detection Evaluation’s (NWGLDE) publication “List of Leak Detection 

Evaluations for UST Systems” (List)1,2. Equipment capabilities, determined by thirdparty evaluation, were compared to federal performance requirements to identify

equipment that is capable of exceeding federal standards. This analysis only includes 

 

1

15th edition, January 2008. 

2 Use of the List is not an endorsement of included equipment.
2

those release detection methods that have applicable data in the List. In order for 

equipment or procedures to be listed by NWGLDE, they must, at a minimum, meet 

federal performance standards.

E

2 Inc. analyzed the performance capabilities of the 237 release detection devices and 

procedures for which the List includes leak rate, Pd, and Pfa. Analysis included the 

following leak detection methods:

 Automatic Line Leak Detectors (ALLD): 

o Electronic Line Leak Detection (ELLD) 

o Mechanical Line Leak Detection (MLLD)

 Automatic Tank Gauging (ATG)

 UST System Testing

o Line Testing

 Line Tightness Test Method

o Tank Testing

 Non-Volumetric Tank Tightness

 Tracer

 Ullage

 Vacuum

 Volumetric Tank Tightness

 Overfill

 Underfill

 Other

o Continuous Automatic Tank Gauging (Continuous ATG)

o Continual Reconciliation

o Qualitative Statistical Inventory Reconciliation (Qualitative SIR)

o Quantitative Statistical Inventory Reconciliation (Quantitative SIR)

The List does not include leak rates, Pd, or Pfa for 241 release detection devices and 

procedures within the following release detection methods, which were therefore not 

included in the capabilities analysis:

 Interstitial Monitoring

o Interstitial Detector (Liquid Phase)

o Continuous Interstitial Line Monitoring (Pressure/Vacuum)

 Groundwater Monitoring

o Out-of-Tank Product Detector (Liquid-Phase)

 Vapor Monitoring

o Out-of-Tank Product Detector (Vapor-Phase)

Federal Standards

The federal standards define the minimum performance requirements for release 

detection methods. Though all of the 237 release detection equipment and procedures are 

subject to federal regulation, federal performance standards are specified for each 

detection method (Table 1). The 241 release detection devices or procedures not 
3

included in the capabilities analysis were not included because the federal regulations do 

not identify performance standards in terms of leak rate, Pd and Pfa for interstitial 

monitoring, ground water monitoring, or vapor monitoring.

Federal Performance Standards3

Leak Detection 

Method

Leak Rate 

(gph) Pd (%) Pfa (%)

ALLD 3.0 95 5

ATG 0.2 95 5

Tank Tightness 0.1 95 5

Line Tightness 0.1 95 5

SIR 0.2 95 5

Table 1. Federal performance standards for release detection.

Results

Distribution of Release Detection Methods

The NWGLDE List includes leak rate, Pd, and Pfa for 13 release detection methods. 

These methods fall into four primary categories: Automatic Line Leak Detection 

(ALLD), Automatic Tank Gauging (ATG), Tightness Testing (TT), and Other. These 

four categories include 237 devices and test procedures. 

Release Detection Methods

Number of 

Release Detection 

Devices/Procedures Subtotal Total Percent

Automatic 

Line Leak 

Detection

Electronic 34 -

52 22 Mechanical 18 -

Automatic Tank Gauging 82 - 82 35

Tightness 

Testing

Line Tightness Tank Method 10 -

59 25 Tank 

Tightness 

Method

NonVolumetric

Tracer 1

Ullage 5 32

Vacuum 26

Volumetric Overfill 15 17 Underfill 2

Other

Continuous ATG 13

- 44 19 Continual Reconciliation 6

Qualitative SIR 13

Quantitative SIR 12

Total 237 - 237 101.00

Table 2. Distribution of release detection methods with leak rate, Pd, and Pfa included in the List.

Note: The final total for the “Percent” column is greater than 100 percent due to rounding. 

There are 52 devices for the ALLD method, representing 22 percent of all analyzed 

methods. Automatic tank gauging includes 82 listed devices, comprising 35 percent of 

all analyzed methods. Line and tank tightness methods include 59 procedures, 

 

3

From 40 CFR 280.43 and 280.44.
4

comprising 25 percent of all analyzed methods. The Other category includes 44 devices 

and procedures representing 19 percent of the analyzed leak detection methods. 

Release Detection Methods Exceeding Federal Regulatory Performance Standards

Review of the 13 release detection methods that are included in the List did not reveal 

any equipment or procedure that failed to meet federal regulatory performance 

requirements. Table 3 summarizes release detection equipment and procedures capable 

of exceeding federal performance requirements.

a. Electronic Line Leak Detection

Analysis determined that 94 percent of the reviewed ELLD devices are capable of 

exceeding the federal performance requirements for leak rate. One hundred percent of 

the reviewed ELLD devices are capable of exceeding the federal performance 

requirements for Pd and Pfa. 

b. Mechanical Line Leak Detection

Analysis determined that none of the reviewed MLLD options are capable of exceeding 

the federal performance requirements for leak rate. One hundred percent of the reviewed 

MLLD options are capable of exceeding the federal performance requirements for Pd and 

Pfa. 

c. Automatic Tank Gauging

Analysis determined that 44 percent of the reviewed ATG systems are capable of 

exceeding the federal performance requirements for leak rate. Ninety-four percent are 

capable of exceeding Pd requirements and 96 percent are capable of exceeding Pfa 

requirements. Of the ATGs capable of exceeding the federal leak rate requirement, 93 

percent can exceed Pd and Pfa requirements. Forty-five percent of ATGs capable of 

exceeding federal Pd standards and 44 percent of ATGs capable of exceeding federal Pfa 

standards are also capable of exceeding federal leak rate standards. Ninety-seven percent 

of ATGs capable of exceeding federal Pd standards are also capable of exceeding federal 

Pfa standards. 

d. Line Tightness

Analysis determined that none of the reviewed Line Tightness procedures are capable of 

exceeding the federal performance requirements for leak rate. Ninety percent of the 

reviewed Line Tightness procedures are capable of exceeding the federal performance 

requirements for Pd and Pfa.

e. Tracer Method

Analysis determined that none of the reviewed Tracer test procedures are listed by

NWGLDE as exceeding the federal performance requirements for leak rate. One 

hundred percent of the reviewed Tracer test procedures are capable of exceeding the 

federal performance requirements for Pd and Pfa.

f. Ullage Test Method
5

Analysis determined that 40 percent of the reviewed Ullage test procedures are capable of 

exceeding the federal performance requirements for leak rate. One hundred percent of 

the reviewed Ullage tests are capable of exceeding the federal performance requirements 

for Pd and Pfa.

g. Vacuum Test Method

Analysis determined that 73 percent of the reviewed Vacuum test procedures are capable 

of exceeding the federal performance requirements for leak rate. One hundred percent of 

the reviewed Vacuum tests are capable of exceeding the federal performance 

requirements for Pd and Pfa.

h. Overfill Test Method

Analysis determined that seven percent of the reviewed Overfill test procedures are 

capable of exceeding the federal performance requirements for leak rate. One hundred 

percent of the reviewed Overfill tests are capable of exceeding the federal performance 

requirements for Pd and Pfa.

i. Underfill Test Method

Analysis determined that 100 percent of the reviewed Underfill test procedures are 

capable of exceeding the federal performance requirements for leak rate, Pd, and Pfa.

j. Continuous ATG

Analysis determined that none of the reviewed Continuous ATGs are capable of 

exceeding the federal performance requirements for leak rate. One hundred percent of 

the reviewed Continuous ATGs are capable of exceeding the federal performance 

requirements for Pd and Pfa.

k. Continual Reconciliation

Analysis determined that none of the reviewed Continual Reconciliation procedures are 

capable of exceeding the federal performance requirements for leak rate. One hundred 

percent of the reviewed Continual Reconciliation procedures are capable of exceeding the 

federal performance requirements for Pd and Pfa.

l. Qualitative SIR

Analysis determined that eight percent of the reviewed Qualitative SIR methods are 

capable of exceeding the federal performance requirements for leak rate. Ninety-two

percent of the reviewed Qualitative SIR methods are capable of exceeding the federal 

performance requirements for Pd and Pfa.

m. Quantitative SIR

Analysis determined that none of the reviewed Quantitative SIR methods are capable of 

exceeding the federal performance requirements for leak rate. One hundred percent of 

the reviewed Quantitative SIR methods are capable of exceeding the federal performance 

requirements for Pd and Pfa.
6

Detection Method

Number 

of 

Options

Exceed Federal 

Leak Rate 

Regulations

Exceed Federal 

Pd Regulations

Exceed Federal 

Pfa Regulations

Count Percent Count Percent Count Percent

ALLD

ELLD 34 32 94.12 34 100.00 34 100.00

MLLD 18 0 0.00 18 100.00 18 100.00

ATG ATG 82 36 43.90 77 93.90 79 96.34

Tightness 

Testing

Line 

Testing

Line Tightness Test 

Method 10 0 0.00 9 90.00 9 90.00

Tank 

Testing

NonVolumetric 

Tank 

Tightness

Tracer 1 0 0.00 1 100.00 1 100.00

Ullage 5 2 40.00 5 100.00 5 100.00

Vacuum 26 19 73.08 26 100.00 26 100.00

Volumetric 

Tank 

Tightness

Overfill 15 1 6.67 15 100.00 15 100.00

Underfill 2 2 100.00 2 100.00 2 100.00

Other

Continuous ATG 13 0 0.00 13 100.00 13 100.00

Continual 

Reconciliation 6 0 0.00 6 100.00 6 100.00

Qualitative SIR 13 1 7.69 12 92.31 12 92.31

Quantitative SIR 12 0 0.00 12 100.00 12 100.00

Totals 237 93 39.24 230 97.05 232 97.89

Table 3. Release detection methods capable of exceeding federal performance standards.

Costs of Equipment Meeting or Exceeding Federal Requirements

Methodology

Costs of equipment in the NWGLDE List were researched using Internet sources and by 

contacting not more than nine distributors of UST leak detection equipment4. Equipment 

distributors were located by searching online industry directories and through general 

Internet searches. Company Web sites were reviewed to confirm that the company sold 

leak detection equipment listed by the NWGLDE and to determine if associated prices 

were available online. None of the nine companies that were interviewed provide 

equipment prices online. 

Interviewed distributors were first contacted with a phone call to discuss the availability

of equipment prices. During phone conversations all nine contacts agreed to review a 

spreadsheet of leak detection equipment e-mailed by E2Inc. and to provide cost estimates 

if possible. Due to the size of the information request, distributors were asked to provide 

any relevant information and it was suggested that they provide at least one price quote 

for each leak detection method. Vendors were contacted on multiple occasions to inquire 

about the status of the cost estimates. Table 4 lists the contacted distributors. 

 

4

In order to comply with the Paperwork Reduction Act, no more than nine contractors were contacted.
7

Company State EPA 

Region Status

Franklin Equipment Services, Inc. NY 2 Declined to participate

Glasgow Equipment FL 4 Declined to participate

Jones & Frank Corporation NC 4 Received

Southern Pump Company NC 4 Not received

Source North America Corporation IL 5 Not received

OES Corporation IN 5 Declined to participate

PSI Equipment Sales CA 9 Not received

Shields Harper CA 9 Declined to participate

Northwest Pump & Equipment OR 10 Not received

Table 4. The nine vendors interviewed for leak detection equipment costs. State column denotes the 

location of branch contacted. 

Results

Of the nine equipment distributors contacted, four officially declined to participate, 

primarily citing time constraints. Four distributors neither declined to participate nor 

provided data. One distributor provided cost information in the form of manufacturers’ 

price lists. Received manufacturer catalogs included:

 Franklin Fueling Systems/Incon (August 2008)

 OMNTEC Mfg., Inc. (October 2008)

 OPW Fuel Management Systems (January 2009)

 Pneumercator Inc. (January 2007)

 Robertshaw Industrial Products (November 2008)

 Veeder-Root Company (September 2008)

Prices for NWGLDE-listed equipment were identified from these catalogs and combined 

to determine total equipment costs. For example, costs of the console, interface module, 

probe, and float kit were totaled to reflect the total equipment cost associated with listed 

ATGs. Required parts were identified through manufacturer catalogs and Web sites. 

In addition to manufacturer catalogs, Internet research yielded equipment costs from 

online distributors. For equipment listed in multiple sources, average prices were 

calculated. For example, prices for the Veeder-Root TLS-350 console were found in the 

manufacturer catalog and two distributor Web sites. Average costs were also used for 

NWGLDE-listed systems that include interchangeable devices (e.g., listings including 

multiple consoles). Costs and performance capabilities are listed in Appendix B. Unless 

otherwise noted, prices are for a single line or tank. 

Costs of 93 NWGLDE-listed equipment and procedures were obtained through 

interviews and online research (Appendix B). Of these 93 devices and procedures, 40

included federal leak rate, Pd, and Pfa standards (Table 5). The remaining 53 devices and 

procedures do not have leak rate, Pd, or Pfa listed by the NWGLDE. Of the equipment 

and procedure options for which costs, leak rate, Pd, and Pfa were obtained, all 40 exceed 

their respective federal Pd and Pfa. 
8

Detection Method

Number of 

NWGDLElisted 

Options

Number of 

Cost 

Estimates 

Obtained

Percent 

of 

Listed 

Options Average Cost

ALLD ELLD 34 6 17.65 $815

MLLD 18 7 38.89 $248

ATG ATG 82 12 14.63 $3,451

Tightness 

Testing

Line 

Testing

Line Tightness Test 

Method 10 4 40 $130 per line

Tank 

Testing

NonVolumetric 

Tank 

Tightness

Tracer 1 0 0

Data not 

available (DNA)

Ullage 5 1 20 $500

Vacuum 26 2 7.69 $5385

Volumetric 

Tank 

Tightness

Overfill 15 1 6.67 $9005

Underfill 2 1 50 $1,0855

Other

Continuous ATG 13 5 38.46 $4,254

Continual 

Reconciliation 6 0 0 DNA

Qualitative SIR 13 0 0 DNA

Quantitative SIR 12 1 8.33 $50 per month

Totals 237 40 16.88

Table 5. Costs for release detection methods that are evaluated to meet federal performance standards.

Within the ten leak detection methods for which cost information was obtained, no 

notable price differences were found between equipment or procedures that meet federal 

leak detection standards and those that exceed federal standards. All ELLD and MLLD 

equipment options for which cost information was obtained are capable of exceeding 

federal leak rate performance standards. Prices were obtained for 12 ATG systems; eight 

of these ATGs exceed the federal leak rate standard and four meet the federal leak rate 

standard. The average cost of these four ATGs was determined to be $124 less than the 

eight that exceed the federal leak rate standard. All equipment for the other eight leak 

detection methods for which cost information was obtained are capable of meeting, but 

not exceeding, federal leak rate performance standards. 

The data provided may not be representative of average costs due to the small sample 

size. Costs of only 16.88 percent of release detection equipment and procedures with 

performance standards were obtained, the majority of which are within four release 

detection methods: ELLD, MLLD, ATG, and Continuous ATG. 

 

5 Costs are per tank at a single-tank site.
9

State Release Detection Requirements

Methodology

E

2

Inc. researched UST release detection regulations for 56 states and territories. State 

and territory release detection requirements were compared with federal leak rate, Pd, and 

Pfa standards as stated in the following sections of 40 C.F.R. 280: 

 § 280.40 General requirements for UST systems

 § 280.43 Methods of release detection for tanks

a. Inventory control

b. Manual tank gauging

c. Tank tightness testing

d. Automatic tank gauging

e. Vapor monitoring

f. Ground-water monitoring

g. Interstitial monitoring

h. Other methods

 § 280.44 Methods of release detection for piping

a. Automatic line leak detectors

b. Line tightness testing

c. Applicable tank methods

Each applicable state and territory rule was classified as having incorporated federal 

regulations, either through adoption by reference or by using language to the same effect 

as the federal regulation text, or as having more stringent requirements than the federal 

rules (Appendix C). 

State compliance with the release detection leak rates set forth in 40 C.F.R. 280 is found 

in Appendix D. Additional state and territory regulations are presented in Appendix E 

and sources of state regulatory information are listed in Appendix F. Appendix G lists 

state rules for each release detection method.

Results

States That Enforce Federal Regulations

Twelve of the 56 states and territories have incorporated the federal UST regulations by 

reference (Arkansas, Commonwealth of Northern Mariana Islands, Georgia, Idaho, 

Kansas, Kentucky, Michigan, Nevada, North Carolina, U.S. Virgin Islands, Utah, and 

West Virginia). An additional eight states and one territory have adopted language 

identical or significantly similar to federal UST regulations, including the same leak rates 

for each leak detection method (Indiana, Iowa, Mississippi, New Jersey, New Mexico, 

North Dakota, Puerto Rico, South Carolina, and Virginia). Regulations for two 

territories, Guam and American Samoa, mention release detection methods but do not 

specify leak rates and do not indicate adoption of federal requirements. The remaining 
10

34 states and territories modified the federal requirements, in most cases to more 

stringent terms and/or by the addition of tests not specified in the federal requirements.

States with More Stringent Regulations

§ 280.43 Methods of release detection for tanks

a. Product inventory control

Five states specify more stringent leak rates for product inventory control than the 

federally required monthly check to detect a release of at least 1.0 percent of flowthrough plus 130 gallons (Table 6). 

State Leak Rate

Maine 0.1 gph

Maryland 0.2 gph, or 150 gallons per month

Massachusetts 0.5% of volume of product dispensed over a period of a 

calendar month

New York 0.75% of tank volume, or losses or gains exceeding 7.5 

gallons per 1,000 gallons delivered

Wisconsin 0.5%, or 5 gallons out of every 1,000 gallons of throughput

Table 6: State product inventory control leak rates that are more stringent than the federal requirements. 

Gallons-per-hour is indicated as “gph.”

Rule §280.43(a)(4) states that deliveries to USTs must be made through a drop tube that 

extends to within one foot of the tank bottom. Several states (Illinois, Michigan, 

Oklahoma, and Wyoming) have changed this rule to have the drop tube extend to within 

six inches of the tank bottom, and Delaware has changed the distance to 5.9 inches.

Several states indicate that product inventory control may not be used as a sole leak 

detection method (e.g., Arizona, Oregon, and Wyoming). Some states have allowed a 

ten-year grace period after USTs achieve compliance with corrosion protection 

requirements before product inventory control is no longer acceptable as a primary

release detection method. Illinois disallowed new sites to utilize inventory control as a 

primary release detection method after May 1, 2003, and Oregon disallowed it at all sites 

after December 22, 2008. 

b. Manual tank gauging

Sixteen states altered Rule §280.43(b)(5) to allow manual tank gauging as the sole 

method of leak detection for tanks larger than the 550 gallon nominal maximum defined 

in the federal regulations (Alaska, California, Colorado, Hawaii, Illinois, Minnesota, 

Missouri, Nebraska, Oklahoma, Oregon, South Dakota, Tennessee, Texas, Washington, 

Wisconsin, and Wyoming). Sixteen states added more stringent leak rates for tanks of 

551-1,000 gallon capacity based on the tank diameter (Table 7; Alaska, California, 

Colorado, Delaware, Florida, Hawaii, Minnesota, Missouri, Nebraska, Oklahoma, 

Pennsylvania, South Dakota, Tennessee, Texas, Wisconsin, and Wyoming). 
11

Tank Capacity Diameter Weekly Standard Monthly Standard

551-1,000 gallons 48 inches 12 gallons 6 gallons

551-1,000 gallons 64 inches 9 gallons 4 gallons

551-1,000 gallons Not specified 13 gallons 7 gallons

Table 7: More stringent manual tank gauging release detection leak rates based on tank diameter for USTs 

with a capacity of 551-1,000 gallons. The last row with unspecified diameter is the federal standard.

Massachusetts changed the weekly standard release detection leak rate for tanks 1,001-

2,000 gallons from 26 gallons to 25 gallons when using manual tank gauging (MTG). 

Illinois changed the rule to apply for tanks of 600 gallon capacity or less. Washington 

state regulations allow for MTG as the sole method of release detection for emergency

power generator tanks of 2,000 gallon capacity or greater. The release detection leak rate 

for such tanks is 0.75 percent weekly standard and 0.5 percent monthly standard.

Illinois specifies that tanks that have been upgraded using the cathodic protection method 

cannot use MTG as a method of release detection and that after May 1, 2003, only tanks 

of 600 gallon capacity or less, unless within the 10-year post cathodic protection 

installation allowance, could utilize MTG for release detection. In California, no tanks 

with secondary containment or capacity greater than 1,000 gallons could use this method 

after December 22, 1998. California also increased the minimum time out of service 

from 36 to 48 hours when utilizing MTG. Oregon has disallowed use of MTG as a 

primary release detection method after December 22, 2008. 

c. Tank tightness testing

New York has a more stringent rate of 0.05 gph, and Maryland has leak rates set in 

accordance with tank capacity, varying from 0.05 gph (0-12,500 gallon capacity tank) to 

0.150 gph (47,501 gallon capacity or greater). Tank tightness testing was disallowed as a 

primary method of release detection in Delaware after December 31, 2008. 

d. Automatic tank gauging

The majority of states and territories require the same ATG leak rate of 0.2 gph stated in 

Rule §280.43(d)(1). Both Oklahoma and California require a 0.1 gph leak rate to be 

detected using ATG in conjunction with monthly inventory reconciliation. Delaware also 

requires a 0.1 gph monthly release detection leak rate for ATG. 

e. Vapor monitoring

Vapor monitoring is currently not, or is scheduled to no longer be, an approved method 

of release prevention in Vermont and Delaware and is not allowed as the sole release 

detection method in Ohio and Wyoming. California includes site-specific restrictions on 

use of vapor monitoring and New Hampshire does not allow vapor monitoring in tanks 

without secondary containment and leak monitoring.

Alaska, Massachusetts, Michigan, and Oregon only allow use of vapor monitoring as 

release detection with prior approval by fire departments and require more stringent 

measures as deemed necessary on a site-by-site basis. New York only allows vapor 

monitoring wells at uncontaminated sites.
12

Florida and Oklahoma require vapor monitoring release detection to be capable of 

detecting a 500 parts per million (ppm) increase over background or historical levels. 

Florida has a 500 ppm leak rate for tanks containing gasoline or equivalent petroleum 

substances and a 50 ppm leak rate for tanks containing kerosene or diesel. Oklahoma has 

less stringent leak rates of 4,000 ppm for gasoline and 1,500 ppm for diesel.

Rule §280.43(e)(3) states that site-specific conditions will not allow for a leak to go 

undetected for more than 30 days. The District of Columbia has reduced this time to a 

maximum of 15 days, North Carolina further reduced it to 14 days, and Delaware omitted 

a time when a leak could go detected altogether, thereby suggesting that a leak should be 

detected immediately regardless of site conditions. 

f. Ground water monitoring

The release detection leak rate indicated in Rule §280.43(f)(6) is 1/8 of an inch free 

product on top of ground water. New York has changed this to be more stringent at 1/64 

of an inch of free product on the ground water surface. 

Eight states do not allow, or are phasing out, the use of ground water monitoring as a 

form or release prevention (Alaska, Florida, Massachusetts, Michigan, New Hampshire, 

Ohio, Rhode Island, and Texas). New Hampshire does not allow ground water 

monitoring as the primary release detection method for tanks without secondary

containment and leak monitoring. In Florida, when product is detected in a ground water 

monitoring well the well to be clear of contamination for 30 consecutive months prior to 

allowing ground water monitoring to be reinstated as a site’s release detection method. 

Alaska, Minnesota, and Oregon require prior approval of the ground water monitoring 

method by the fire department. 

g. Interstitial monitoring

Florida has set the release detection leak rate as 0.2 gph and Maine has set the leak rate at 

150 gallons or more within 30 days. For USTs using vacuum monitoring, The District of 

Columbia considers a leak to be indicated if the vacuum falls below five inches of 

mercury, whereas Vermont and Florida consider any gain or loss in vacuum or pressure 

to be indicative of a leak. Continuous monitoring to detect water, regulated substance, 

and/or regulated substance vapors is required in New Hampshire and Rhode Island. 

Georgia and Maine require secondary containment and interstitial monitoring for all new 

or replaced USTs and associated piping.

h. Other methods

The majority of states and territories incorporated rule §280.43(h)(1), with the exceptions 

of New Hampshire, New York, Rhode Island, and Vermont, which do not permit 

methods other than those specifically listed in their Administrative Codes. California, 

Florida, Massachusetts, Oklahoma, and Wisconsin also do not permit release detection 

methods not listed in their Codes, but these five states do specifically include statistical 

inventory reconciliation as an acceptable "other" release detection method. 
13

§ 280.44 Methods of release detection for piping

a. Automatic line leak detectors

All states and territories included the federal rule §280.44(a) for an automatic line leak 

detection rate of 3.0 gph at 10 pounds per square inch (psi) within one hour. Maine 

requires continuous line leak detection monitoring for all piping sumps including 

dispenser pumps and pans.

b. Line tightness testing

All states and territories except New York included the federal rule §280.44(b) leak rate 

of 0.1 gph at one and one-half times the operating pressure. New York had a more 

stringent leak rate of 0.05 gph. Michigan requires that secondary containment piping 

shall be tested at 5 psi for the minimum time of one hour. 

c. Applicable tank methods

Thirty-nine states and territories included language from rule §280.44(c) stating that 

applicable tank methods could be used as a release detection method for piping. This 

language was omitted from the remaining 14 states for which information was found 

(California, Delaware, Florida, Maine, Massachusetts, New Hampshire, New York, Ohio, 

Oklahoma, Oregon, Rhode Island, South Dakota, Vermont, and Wisconsin). 

Additional tests beyond federal requirements

Seventeen states include statistical inventory reconciliation (SIR) in their regulations as 

an acceptable release detection method (Alaska, California, Connecticut, Florida, Illinois, 

Louisiana, Maine, Maryland, Massachusetts, Oklahoma, Oregon, Pennsylvania, 

Tennessee, Texas, Washington, Wisconsin, and Wyoming). Eleven of these states use

the federal release detection leak rate from §280.43(h)(1) “Other methods” of 0.2 gph or 

a release of 150 gallons within a month. The exceptions are listed in Table 8:

State Release detection leak rate

Connecticut "abnormal loss or gain which is not explainable by spillage, 

temperature variations or other known causes"

Maine 0.1 gph

Massachusetts "statistically significant loss"

Oklahoma None specified

Pennsylvania absolute value of calculated leak rate exceeds leak threshold

Table 8: State release detection leak rates for USTs being monitored with statistical inventory 

reconciliation. These values differ from the federal leak rate for “Other methods” of release detection, 

which are 0.2 gph or 150 gallons within a month.

Illinois currently allows SIR as a release detection method but is discontinuing its use. 

No new requests to use the method will be accepted after the May 1, 2003 cut-off date, 

and sites where the method has been interrupted may not resume its use. Statistical 

inventory reconciliation has been banned from use on systems with blending pumps or 

siphon tanks, effective in Illinois after January 1, 2006. 

Wyoming also lists the use of tracer surveys and passive acoustical sensing as acceptable 

“Other methods” of release detection in the state, provided that they can detect a leak rate 
14

to comply at minimum with the 0.2 gph or 150 gallons per month rate in the federal 

regulation. 

California state regulations require visual inspection of all visible exterior surfaces of an 

UST to be conducted at least daily. Additionally, single-walled tanks that are located 

within 1,000 feet of a public drinking water well must implement enhanced leak detection 

testing, capable of detecting a leak rate of at least 0.005 gph. California additionally

mandates soil sampling in association with boring observation wells for vapors and/or 

ground water. Soil samples must be collected at five foot intervals, including ground 

surface and termination depth, and then analyzed in a state-certified laboratory for one or 

more of the most persistent constituents that have been stored in the UST. 

In Connecticut, UST facilities that did not have release detection equipment when the 

state regulations became effective in 1994 must use failure determination testing until one 

of the federally listed release detection methods is in place.

Costs of Interstitial Monitoring

Methodology

E

2

Inc. used EPA and industry Web sites and the NWGLDE List to identify applicable 

methods of interstitial monitoring. Identified methods include:

 Pressure

 Vacuum

 Liquid-filled

 Automatic Tank Gauge (with liquid point sensor in interstice)

Costs of these interstitial monitoring methods were researched using Internet sources and 

by contacting not more than nine contractors (Table 9). Contractors were identified 

through online industry directories, state UST Web sites, and general Internet searches. 

Company Web sites were reviewed to determine if they installed and monitored 

interstitial monitoring systems and if associated costs were available online. Additional 

cost estimates were obtained from a November 2007 Affidavit by Charles Frey, Vice 

President of Highland Tank and Manufacturing Company, Inc and board member of the 

Steel Tank Institute.

Selected contractors were first contacted with a phone call to discuss the availability of 

cost estimates. During phone conversations all nine contacts agreed to review a 

spreadsheet of interstitial monitoring methods e-mailed by E2Inc. and provide cost 

estimates for interstitial monitoring equipment, installation, operation and maintenance, 

and monitoring and testing, if possible. 
15

Contractor State EPA 

Region Status

Valley Equipment Company NY 2 Declined to participate

CrompCo, LLC PA 3 Received

Mid Valley Supply KY 4 Not received

Minnesota Petroleum MN 5 Received

US Tank Alliance OH 5 Declined to participate

PetroServ Inc TX 6 Not received

Tanknology MD 6 Received

Petro West Inc. UT 8 Not received

Service Station Systems, Inc. CA 9 Received

Table 9. Contractors contacted for interstitial monitoring and integrity test cost estimates. The state 

column denotes the location of branch contacted. 

Results

Of the nine contractors contacted, four provided estimates for costs associated with 

interstitial monitoring systems (Table 10). Two of the remaining five contractors 

officially declined to participate. All estimates are for a three tank site with the conduit 

already in place.

The purchase cost for vacuum systems were an estimated $549 less than liquid-filled 

systems. The combined purchase and installation costs of liquid-filled systems were on 

average $944 dollars more than ATG systems with liquid point sensors. Costs for 

purchase and installation of pressure-based systems were not obtained. These data may

not be representative of average costs due to the small sample size. 

Type of Interstitial 

Monitoring

Average Estimated Costs6

Purchase Installation

Annual 

Operation and 

Maintenance

Annual 

Monitoring 

and Testing

Pressure DNA DNA DNA $488

Vacuum $10,191 DNA DNA $488

Liquid-filled

$10,740 DNA

$5007

$12,0008

ATG (with liquid 

point sensor) $11,0568

$5007

DNA $300

Table 10. Average estimated costs for interstitial monitoring. DNA denotes data not available. 

One contractor estimated annual monitoring and testing costs for pressure and vacuum 

interstitial monitoring systems as $488 for a three tank site. One contractor estimated 

 

6 All estimates are for a three tank site with the conduit already in place.

7 Contractor did not distinguish operation and maintenance and monitoring and testing costs. 

8 Contractor did not distinguish purchase and installation costs.
16

annual monitoring and testing costs of periodic ATGs as $300. Another contractor did 

not distinguish between annual operation and maintenance costs and annual monitoring 

and testing costs for ATG systems and estimated the combined annual cost as $500. 

These data may not be representative of average costs due to the small sample size. 

Periodic Integrity Testing of Interstitial Space

Methodology

E

2

Inc. first determined appropriate integrity test methods under the scope of work. 

Identified integrity test methods include hydrostatic, vacuum, and pressure. These tests 

are applied to secondarily-contained UST systems, including:

 Tanks,

 Piping,

 Tank top sumps,

 Dispenser pans, and

 Spill buckets

Costs of methods for testing integrity of secondarily-contained UST components were 

researched using Internet sources and by contacting not more than nine contractors. 

Contractor Web sites were reviewed to confirm whether they installed and monitored 

interstitial monitoring systems and if cost estimates were available online. The same nine 

contractors were interviewed as for the interstitial monitoring costs (see Table 9). 

Contractors were first contacted with a phone call to discuss the availability of cost 

estimates. During phone conversations all nine contacts agreed to review a spreadsheet 

of integrity test methods e-mailed by E2Inc. and provide associated cost estimates, if 

possible. 

Results

Of the nine contractors contacted, two provided estimates for the cost of integrity testing 

of secondarily-contained systems (Table 11). The data provided may not be 

representative of average costs due to the small sample size. 

UST Component Test Method

CrompCo, LLC

Costs Tanknology Costs

Tank

Hydrostatic DNA DNA

Pressure/Vacuum $150 per tank $125 per tank

Piping

Hydrostatic DNA DNA

Pressure/Vacuum $100 per line $125 per line

Tank top sumps

Hydrostatic $700 per site DNA

Pressure/Vacuum $700 per site DNA

Dispenser Pans

Hydrostatic $300 per site $150 per dispenser 

pan or sump

Pressure/Vacuum $300 per site DNA
17

UST Component Test Method

CrompCo, LLC

Costs Tanknology Costs

Spill Buckets

Hydrostatic $600 per site

$50 per spill bucket; 

$100 per site for 

waste fluid disposal

Pressure/Vacuum $600 per site $50 per spill bucket

Table 11. Cost estimates for integrity testing of secondarily contained components. 

Average costs of interstitial integrity tests are $137.50 per tank and $112.50 per line for 

piping. Costs of testing tank top sumps were estimated by one contractor as $700 per 

site. Costs for testing dispenser pans were reported as $300 per site or $150 per dispenser 

pan or sump. Testing costs for spill buckets were estimated as $600 per site or $50 per 

spill bucket. One contractor reported that the hydrostatic test for spill buckets includes an 

additional $100 for disposal of waste water. 

Cost saving opportunities

Interviewed contractors reported that cost-saving opportunities are possible, but that they

occur on a site-by-site basis. Although no discount was reported for testing multiple 

systems at a site, a discount of $150 was reported for combining environmental testing 

with air testing. Additional online research found one UST contractor’s Web site that 

advertised a 10 percent discount if the tank owner booked testing services for the 

following year.