Petroleum Bulk Storage Underground Tank Tightness Testing FAQ's

Note: This information is intended to provide tank owners and operators answers to commonly asked questions. Tank owners should obtain a copy of the state Petroleum Bulk Storage (PBS) regulations, determine which Subparts apply to their tank system(s), and read them carefully and in their entirety. Tank owners and operators are responsible for complying with all technical requirements in the PBS regulations.

1. What is a tightness test?

A tightness test is a means of determining whether a storage tank and/or its piping system are leaking. DEC requires using a test that can detect a tank or piping leak of 0.1 gallons per hour (gph) (with a probability of at least 95% and no more than 5% probability of false alarm. For line (piping) tightness tests, the test must detect 0.1-gph leaks at one and one-half (1.5) times the operating pressure. The test(s) used must detect leaks from the entire tank system component - tank tests must include the liquid-filled portion of the tank AND the vapor space above the petroleum, while piping tests must include all portions of underground piping (that routinely contain petroleum). To accomplish this, one of the four following tests can be used:

• A volumetric overfill test¹ (a separate piping test may also be needed depending on the tank system configuration);
• A volumetric underfill test in conjunction with a non-volumetric ullage (vapor space) test and a separate piping test;
• A non-volumetric vacuum test (a separate piping test may also be needed depending on the tank system configuration); or
• A non-volumetric tracer test.

There are many variables which can affect the ability of each of these tests to detect a leak. One variable commonly involved in all test methods (except for the separate piping test) is the depth of groundwater in relation to the tank. In order to compensate for the presence of groundwater around the tank, its depth must be determined as close to the tank as possible by using either a well or well point. (Without this information on the test report, the test is invalid.)

Because some tests compensate for variables better than others, DEC has determined that the test methods listed by the National Work Group on Leak Detection Evaluations (NWGLDE) meet the requirements set forth in the regulations and give results that are acceptable to DEC. A list of all leak detection methods, including tightness tests and a specification page for each leak detection method that indicates how that method must be used, is available at the NWGLDE website (See "Links Leaving DEC's Website" on the right-hand side of this page). Tests must be conducted in accordance with this specification in order to be acceptable. (When looking at the NWGLDE website, click "Testing Methods" on the left-hand side and then look under one of the following categories: line tightness test method, non-volumetric tank tightness test method (tracer), non-volumetric tank tightness test method (ullage), non-volumetric tank tightness test method (vacuum), volumetric tank tightness test method (underfill), or volumetric tank tightness test method (overfill)¹.)

¹Note that an overfill method is generally not recommended to be used since using this method on a tank that is not tight may result in a release of petroleum to the environment, or exacerbate an ongoing release.

2. What NYS law requires tightness testing?

In an effort to prevent leaks and spills, the New York State Legislature passed the Petroleum Bulk Storage (PBS) Law - Article 17, Title 10, of the Environmental Conservation Law - requiring DEC to develop and enforce a State code for storage and handling of petroleum. The regulations are found in Part 613 of Title 6 of the New York Codes, Rules and Regulations 6 NYCRR Part 613 (215 pages, 1.2 MB).

Part 613 is divided into six subparts; Subparts 2 and 3 require, among other things, tightness testing of specific underground storage tank (UST) and piping systems.

3. Which tank and piping systems must be tested for tightness and how often must they be tested?

Only certain underground ² storage tanks and associated piping systems must be tested for tightness (they must be tested either every year or every three (3) years depending on the type of tank system/piping system).

UST systems fall under either Subpart 2 (6 NYCRR Part 613-2) or Subpart 3 (6 NYCRR Part 613-3).
Subpart 3 UST systems are defined in section 613-3.1(a) as those that:

• contain heating oil used for on-premises consumption (i.e., the most common SP3 UST system);
• have a design capacity of 1,100 gallons or less and are used to store motor fuel for non-commercial purposes (i.e., not for resale) at a farm or residence;
• are part of an emergency generator system at nuclear power generation facilities regulated by the Nuclear Regulatory Commission (under 10 CFR Part 50); or
• consist of a field-constructed tank.

Any UST system that is not a Subpart 3 UST system is a Subpart 2 UST system.

The following is a summary of the tightness testing frequencies for different types of tank systems, subject to the exemptions/qualifiers specified in the following two sections:

²Tanks in subterranean vaults or basements which cannot be visually inspected are considered underground tanks. However, if the tank in the vault or basement is accessible for visual inspection, the tank is considered an aboveground storage tank (AST).

4. How often must Subpart 3 tanks/piping be tested?

TANKS - Subpart 3: USTs that are part of a Subpart 3 tank system must be tested for tightness at least every year. However, no annual tightness testing is required for a Subpart 3 UST that is:

• storing #5 or #6 fuel oil;
• equipped with an acceptable leak detection method which is being monitored for leaks weekly;³
• installed on or after December 27, 1986; or
• (part of a tank system that has been) permanently closed.

³Acceptable weekly tank leak detection methods include: automatic tank gauging; vapor monitoring; groundwater monitoring; interstitial monitoring; and weep holes (i.e., holes in the base of a concrete form encasing a tank installed before 12/27/1986, used to detect a leak from any portion of the tank and are directly visible to an observer).

PIPING - Subpart 3: Underground⁴ pressurized and suction piping, for UST systems subject to Subpart 3, must be tested for tightness at least every year. However, no annual tightness testing is required for:

• piping for UST systems storing #5 or #6 fuel oil;
• pressurized piping equipped with an automatic line leak detector (ALLD);
• piping monitored for leaks weekly with interstitial monitoring;
• piping installed on or after December 27, 1986;
• piping (installed before December 27, 1986) that meets design/construction standards for piping installed on or after December 27, 1986;
• exempt suction piping^5_; and
• piping for UST systems that have been permanently closed.

⁴If the piping is part of an aboveground/underground combination, only the underground portion must be tested for tightness.

⁵Exempt suction piping is defined as having (all of) the following characteristics:

• the underground piping operates at less than atmospheric pressure;
• the underground piping is sloped so that the contents of the pipe will drain back into the UST if the suction is released;
• only one check valve is included in each suction line; and
• the check valve is located directly below and as close as practicable to the suction pump.

5. How often must Subpart 2 tanks/piping be tested?

TANKS - Subpart 2: USTs that are part of a Subpart 2 tank system do not require tightness testing as these tanks are required to be equipped with an acceptable leak detection method.

PIPING - Subpart 2: Underground⁶ pressurized piping must be tested for tightness at least every year, while underground⁶ suction piping must be tested at least every three (3) years. However, no tightness testing is required for:

• pressurized piping that is equipped with an automatic line leak detector (ALLD) AND an acceptable leak detection method which is being monitored for leaks weekly⁶;
• suction piping that is equipped with an acceptable leak detection method which is monitored for leaks weekly⁷;
• exempt suction piping⁸;
• piping installed after October 11, 2015; and
• piping for UST systems that have been permanently closed.

⁶If the piping is part of an aboveground/underground combination, only the underground portion must be tested for tightness.
⁷Acceptable weekly piping leak detection methods include: vapor monitoring; groundwater monitoring; interstitial monitoring; and statistical inventory reconciliation (SIR).
⁸Exempt suction piping is defined (in section 613-2.3(b)(2)(i)(b)) as having (all of) the following characteristics:

• the underground piping operates at less than atmospheric pressure;
• the underground piping is sloped so that the contents of the pipe will drain back into the UST if the suction is released;
• only one check valve is included in each suction line; and
• the check valve is located directly below and as close as practicable to the suction pump.

6. Who is responsible for ensuring that tank systems are tested for tightness?

Under the regulations, both the tank owner and the tank operator are responsible for having tanks and piping tested periodically by a qualified technician. Note: Tank owners/operators in New York City (NYC) are responsible for contacting the Fire Department (FDNY) prior to testing tank systems storing motor fuel.

7. Who is a qualified tester and where do I find one? 

Each test manufacturer trains and certifies technicians who perform that test. Each authorized technician will have a certification that indicates that they have been properly trained as well as an expiration date for that certification. The certification number for the technician performing the test must be included on the test report. Companies that provide tank testing services can be found online, or you might get a referral from your petroleum supplier. If you have any questions about a technician, call the test manufacturer. The manufacturer's phone number is on the list found at the website for the National Work Group on Leak Detection Evaluations (NWGLDE) (See "Links Leaving DEC's Website" on the right menu of this page).

8. What if my tank system fails a tightness test? 

A failed tightness test indicates a suspected leak, which must be reported to the State Spill Hotline within two (2) hours by the tank owner or the tank operator. The toll-free State Spill Hotline is 1-800-457-7362 from within New York State, and 518-457-7362 when calling from outside the state. The next step is to quickly determine the source of the leak, whether tank or piping. Once the source is isolated, the tank system must be promptly emptied, and the leaking tank system component taken out-of-service and repaired or replaced in accordance with the PBS regulations (6 NYCRR 613-2.4(d)(2) for Subpart 2 UST systems and 613-3.4(d)(2) for Subpart 3 UST systems).

9. How are test results reported? 

The test report must include the test results, calculations, how depth to groundwater was determined, and all information required in section 613-3.3(c)(1)(ii)(b). A copy of this test report must be sent to the DEC Regional Office by the tank owner or the test technician, within thirty (30) days after the test is performed. The report must also be kept on file by the tank owner for at least three (3) years. Note that the means of determining the depth to groundwater is not required to be on the report for the separate piping test.

10. What should I do if I think the tightness test notice has been sent to me in error? 

If you believe that your tank system is not required to be tested, you must call the DEC Regional Office and speak with a member of the PBS staff. They will guide you on the requirements for your tank system. If you ignore this tightness testing notice, follow-up enforcement may occur.