Rules & Regulations of the State of Tennessee
Title 0400 - Environment and Conservation
Subtitle 0400-18 - Division of Petroleum Underground Storage Tanks
Chapter 0400-18-01 - Underground Storage Tanks Program
Section 0400-18-01-.04 - RELEASE DETECTION

Universal Citation: TN Comp Rules and Regs 0400-18-01-.04

Current through September 24, 2024

(1) General requirements for release detection.

(a) Owners and/or operators of UST systems shall provide a method, or combination of methods, of release detection that:

1. Can detect a release from any portion of the tank and the connected underground piping that routinely contains petroleum;

2. Is installed and calibrated in accordance with the manufacturer's instructions and is operated and maintained in accordance with one of the following:

(i) The manufacturer's instructions;

(ii) A code of practice developed by a nationally recognized association or independent testing laboratory; or

(iii) Requirements determined by the Division to be no less protective of human health and the environment than the two options listed in subparts (i) and (ii) of this part.

3. Ensures that electronic and mechanical components are tested for proper operation in accordance with subparts 2.(i) through (iii) of this subparagraph. The test must be performed at least annually, and at a minimum, as applicable to the facility, cover the following components and criteria:

(i) Automatic tank gauge and other controllers: test alarm; verify system configuration; test battery backup;

(ii) Probes and sensors: inspect for residual buildup; ensure floats move freely; ensure shaft is not damaged; ensure cables are free of kinks and breaks; test alarm operability and communication with controller;

(iii) Automatic line leak detector: test operation to meet criteria in subparagraph (4)(a) of this rule by simulating a leak; and

(iv) Vacuum pumps and pressure gauges: ensure proper communication with sensors and controller.

4. Meets the performance requirements of paragraph (3) or (4) of this rule or subparagraph (2)(d) of Rule 0400-18-01-.17, as applicable, with any performance claims and their manner of determination described in writing by the equipment manufacturer or installer. In addition, the methods listed in paragraphs (3) and (4) of this rule and subparagraph (2)(d) of Rule 0400-18-01-.17, as applicable shall be capable of detecting the leak rate or quantity specified for that method in subparagraphs (3)(a), (b), and (c) or (4)(a) and (b) of this rule with a probability of detection of 0.95 and a probability of false alarm of 0.05.

5. Has had a third party evaluation reviewed by the National Work Group on Leak Detection Evaluations (NWGLDE) and a listing of the leak detection equipment or method appears on the list maintained by the NWGLDE. However, any NWGLDE listed leak detection equipment or method for which there is no longer any technical support available may not be used to meet the requirements of this paragraph.

(b) When a release detection method operated in accordance with paragraph (3) or (4) of this rule or subparagraph (2)(d) of Rule 0400-18-01-.17, as applicable, indicates a release may have occurred, owners and/or operators shall notify the Division in accordance with Rule 0400-18-01-.05. If more than one method of release detection is operated on a UST system, a suspected release shall be reported to the Division in accordance with Rule 0400-18-01-.05 if any one of the release detection methods indicates a release may have occurred.

(c) If a method of release detection that complies with the requirements of this rule cannot be applied to and/or operated for any UST system, the owner and/or operator of that UST system shall complete the closure procedures in Rule 0400-18-01-.07.

(d) If a release detection method selected by the owner and/or operator cannot meet the requirements in paragraphs (3) and (4) of this rule and subparagraph (2)(d) of Rule 0400-18-01-.17, as applicable, to the satisfaction of the Division, then the owner and/or operator shall select another method of release detection.

(e) The dispenser cover shall be opened and a visual inspection for petroleum releases, including seeps and drips, shall be performed at least quarterly, that is, at least once every three months. A log of these inspections showing at a minimum the last 12 months shall be maintained by the owner and/or operator.

(f) Under-dispenser containment sumps for motor fuel dispensers required by subparagraph (1)(c) or paragraph (6) of Rule 0400-18-01-.02 to be secondarily contained in accordance with subparagraph (2)(c) of Rule 0400-18-01-.02 shall be visually inspected at least quarterly, that is, at least once every three months. A log of these inspections, showing at a minimum the last 12 months, shall be maintained by the owner and/or operator. The visual inspection shall check for the presence of petroleum and/or water in the sumps. If liquid is observed in the dispenser sump, the liquid shall be removed from the sump in such a manner as to prevent the release of petroleum into the environment.

(2) Requirements for petroleum UST systems.

Owners and/or operators of petroleum UST systems shall provide release detection for tanks and piping as follows:

(a) Tanks.

Tanks shall be monitored at least monthly for releases using one of the methods listed in subparagraphs (3)(c) through (f) of this rule, except that tanks which meet the volume, diameter, and test duration requirements as set forth in subpart (3)(a)1.(i) of this rule may use manual tank gauging (conducted in accordance with subparagraph (3)(a) of this rule).

(b) Piping.

Underground piping that routinely contains petroleum shall be monitored for releases in a manner that meets one of the following requirements:

1. Pressurized piping.

Underground piping that conveys petroleum under pressure shall:

(i) Be equipped with an automatic line leak detector conducted in accordance with subparagraph (4)(a) of this rule; and

(ii) Have an annual line tightness test conducted in accordance with subparagraph (4)(b) of this rule or have monthly monitoring conducted in accordance with subparagraph (4)(c) of this rule.

2. Suction piping.

Underground piping that conveys petroleum under suction shall either have a line tightness test conducted at least every three years and in accordance with subparagraph (4)(b) of this rule, or use a monthly monitoring method conducted in accordance with subparagraph (4)(c) of this rule. No release detection is required for suction piping that is designed and constructed to meet the following standards:

(i) The below-grade piping operates at less than atmospheric pressure;

(ii) The below-grade piping is sloped so that the contents of the pipe will drain back into the storage tank if the suction is released;

(iii) Only one check valve is included in each suction line;

(iv) The check valve is located directly below and as close as practical to the suction pump; and

(v) A method is provided that allows compliance with subparts (ii) through (iv) of this part to be readily determined.

(3) Methods of release detection for tanks.

Each method of release detection for tanks used to meet the requirements of paragraph (2) of this rule shall be conducted in accordance with the following:

(a) Manual tank gauging.

1. Manual tank gauging shall only be applicable to tanks as set forth below:

(i) Tanks which meet the volume, diameter and test duration requirements as set forth below may use manual tank gauging as the sole method of release detection:

Nominal Capacity	Tank Diameter	Minimum Duration Of Test
up to 550 gallons	*	36 hours
551 - 1000 gallons	64 inches	44 hours
551 - 1000 gallons	48 inches	58 hours

*Any diameter of tank up to 550 gallons may use manual tank gauging as the sole method of release detection if the duration of the test is at least 36 hours.

(ii) Manual tank gauging shall not be used as the sole method of release detection for tanks of 551 to 1000 gallons nominal capacity which cannot meet the diameter or test duration requirements as set forth in subpart (i) of this part or for tanks of 1001 to 2000 gallon nominal capacity. These tanks shall use manual tank gauging in combination with tank tightness testing in accordance with subparagraph (2)(a) of this rule.

(iii) Tanks of greater than 2000 gallons nominal capacity using this method shall not meet the requirements of this rule.

2. Manual tank gauging shall meet the following requirements:

(i) Tank liquid level measurements are taken at the beginning and ending of a period of using the appropriate minimum duration of the test value in the table in subpart 1.(i) of this subparagraph during which no liquid is added to or removed from the tank;

(ii) Level measurements are based on an average of two (2) consecutive stick readings at both the beginning and ending of the required period;

(iii) The equipment used is capable of measuring the level of petroleum over the full range of the tank's height to the nearest one-eighth of an inch;

(iv) Petroleum levels are measured and recorded to an accuracy of at least the nearest one-eighth of an inch;

(v) A release is suspected and subject to the requirements of Rule 0400-18-01-.05 if the variation between beginning and ending measurements exceeds the weekly or monthly standards in the following table:

Nominal Capacity	Tank Diameter	Minimum Duration Of Test	Weekly Standard (One Test)	Monthly Standard (Average Of 4 Tests)
Up to 550 gallons		36 hours	10 gallons	5 gallons
551 - 1000 gallons		36 hours	13 gallons	7 gallons
551 - 1000 gallons	64 inches	44 hours	9 gallons	4 gallons
551 - 1000 gallons	48 inches	58 hours	12 gallons	6 gallons
1001 - 2000 gallons		36 hours	26 gallons	13 gallons

(b) Tank tightness testing.

1. Tank tightness testing shall be capable of detecting a 0.1 gallon per hour leak rate from any portion of the tank that routinely contains petroleum while accounting for the effects of thermal expansion or contraction of the petroleum, vapor pockets, tank deformation, evaporation or condensation, and the location of the water table.

2. Tank tightness testing devices, automatic tank gauging devices or other equipment may be used provided that the testing meets the performance criteria set forth in part 1. of this subparagraph.

3. The information relating to the tank tightness test shall be reported in a format established by the Division. The tank tightness test report shall include, but is not necessarily limited to the following information:

(i) Information which identifies the tank and the facility;

(ii) Information which identifies the test method and test conditions established by the manufacturer's specifications and/or required by the third party certification of the method;

(iii) Information which identifies the person and/or company performing the test;

(iv) Data gathered during the performance of the test; and

(v) Results expressed as follows:

(I) Leak rate in gallons per hour and as "Pass" or "Fail" for volumetric test methods; or

(II) "Pass" or "Fail" for non-volumetric test methods.

4. A release is suspected and subject to the requirements of Rule 0400-18-01-.05 if the method detects a release rate greater than that established by the manufacturer's specifications and/or third party certification.

Equipment for automatic tank gauging shall be permanently installed in the tank and shall meet one of the following requirements:

1. For automatic tank gauging devices capable of detecting at least a 0.2 gallon per hour leak rate from any portion of the tank that routinely contains petroleum:

(i) The monitor shall be placed in the leak test mode at least once per month; and

2. For automatic tank gauging systems which are capable of detecting at least a 0.2 gallon per hour leak rate from any portion of the tank that routinely contains petroleum using continuous statistical release detection:

(i) The automatic tank gauging system shall be placed in the leak test mode at least once per month if a test cannot be obtained during any one month period, except for those systems which also use statistical inventory reconciliation in accordance with subparagraph (e) of this paragraph; and

(ii) A release is suspected and subject to the requirements of Rule 0400-18-01-.05 if the monitoring results indicate that the underground storage tank has had a release above the established threshold of the automatic tank gauging device as determined through third party certification, except that those systems also using statistical inventory reconciliation shall report suspected releases in accordance with subparagraph (e) of this paragraph.

(d) Interstitial monitoring.

Interstitial monitoring between the UST system and a secondary barrier immediately around it may be used, but only if the system is designed, constructed and installed to detect a leak from any portion of the tank that routinely contains petroleum and also meets one of the following requirements:

1. For double-walled UST systems, the monitoring method shall:

(i) Be able to detect a leak through the inner wall in any portion of the UST system that routinely contains petroleum;

(ii) Provide continuous monitoring; and

(iii) Be installed, maintained and operated in accordance with guidance provided by the division.

2. For tanks with an internally fitted liner, an automated device can detect a leak between the inner wall of the tank and the liner, and the liner is compatible with the substance stored.

(e) Statistical inventory reconciliation.

Statistical analysis of inventory, delivery and dispensing data collected over a period of time shall meet the following requirements:

1. Inventory control shall be conducted in accordance with the following requirements:

(i) Inventory volume measurements for petroleum inputs, withdrawals, and the amount still remaining in the tank are recorded each operating day;

(ii) Petroleum levels are measured and recorded to an accuracy of at least the nearest one-eighth of an inch over the full range of the tank's height;

(iii) The petroleum inputs are reconciled with delivery receipts by measurement of the tank inventory volume before and after delivery;

(iv) Deliveries are made through a drop tube that extends to within one foot of the tank bottom;

(v) Petroleum dispensing is metered and recorded within the local standards for meter calibration or an accuracy of six (6) cubic inches for every five gallons of petroleum withdrawn, and the meters are calibrated at least annually; and

(vi) The measurement of any water level in the bottom of the tank is made and recorded to the nearest one-eighth of an inch at least once a month.

2. A report shall be generated monthly, after the end of the data collection for that time period. The report shall include, but is not limited to the following:

(i) The inventory records used, that is, the raw data (data consisting of daily product levels, deliveries and sales as determined by direct measurement or automatic tank gauges, and daily reconciliation of measured amounts in the tank compared with calculated amounts in the tank); and

(ii) The statistical inventory reconciliation determination;

3. For quantitative statistical inventory reconciliation methods, the numerical leak rate shall be reported unless the statistical inventory reconciliation determination results in an "Inconclusive" under the provisions of subpart 4.(iii) of this subparagraph;

4. The statistical inventory reconciliation determination shall be reported using the term "Pass", "Fail" or "Inconclusive". For quantitative statistical inventory reconciliation methods the applicable term shall be used in accordance with subparts (i) through (iii) of this part:

(i) If the calculated leak rate does not exceed 0.10 gallons per hour, the results shall be reported as a "Pass";

(ii) If the calculated leak rate exceeds 0.10 gallons per hour, the results shall be reported as a "Fail";

(iii) If the leak rate cannot be calculated using the available data, the results shall be reported as an "Inconclusive";

5. If there are too few operational days for statistical inventory reconciliation to successfully analyze during any month, then another method of release detection shall be utilized during that month; and

6. The owner and/or operator shall report a suspected release in accordance with Rule 0400-18-01-.05:

(i) When the statistical inventory reconciliation determination is reported as a "Fail"; or

(ii) When two consecutive "Inconclusive" statistical inventory reconciliation determinations are reported.

(f) Other methods of release detection.

1. Prior to use by the tank owner and/or operator, division approval shall be obtained in writing for any other type of release detection method, or combination of methods.

(i) The written approval shall be kept on file at the facility or at the place of business of the tank owner and/or operator while the method is being utilized for release detection and for at least 12 months thereafter. If the owner and/or operator is unable to maintain the approval document due to closure of the facility, the approval document shall be submitted to the division with the closure records submitted in accordance with subparagraph (7)(c) of Rule 0400-18-01-.07.

(ii) The written approval shall be valid for two years. The written approval must be renewed every two years thereafter.

2. The Division may approve another method if that method has been third party certified to effectively and consistently detect releases. In reviewing methods for division approval, the Division shall consider the size of release that the method can detect and the frequency and reliability with which it can be detected as set forth in the third party certification.

3. If the method has been approved in writing by the Division, the owner and/or operator shall comply with any conditions imposed by the Division on its use to ensure the protection of human health and the environment.

(4) Methods of release detection for piping.

Each method of release detection for piping used to meet the requirements of paragraph (2) of this rule shall be conducted in accordance with the following:

(a) Automatic line leak detectors.

Methods which alert the operator to the presence of a leak by restricting or shutting off the flow of petroleum through piping or triggering an audible or visual alarm may be used only if they detect leaks of three gallons per hour at ten pounds per square inch line pressure within one hour. An annual test of the operation of the leak detector shall be conducted in accordance with guidance provided by the Division.

(b) Line tightness testing.

A periodic test of piping may be conducted only if it can detect a 0.1 gallon per hour leak rate at one and one-half times the operating pressure.

Interstitial monitoring between the primary piping and the secondary barrier immediately around it may be used, but only if the system is designed, constructed and installed to detect a leak from any portion of the piping that routinely contains petroleum and also meets one of the following requirements:

1. For double-walled UST systems, the monitoring method shall:

(i) Be able to detect a leak through the inner wall in any portion of the UST system that routinely contains petroleum;

(ii) Operate continuously as designed, and provide 30 day periodic testing;

(iii) Be installed, maintained and operated in accordance with guidance provided by the Division; and

(iv) If owners and/or operators of UST systems have containment sumps used for interstitial monitoring of piping, the containment sumps must meet the following requirements to ensure the equipment is operating properly and will prevent releases to the environment:

(I) Containment sumps used for interstitial monitoring of piping must prevent releases to the environment by meeting one of the following:

I. The equipment is double walled and is periodically monitored at a frequency not less than the frequency of the walkthrough inspections described in paragraph (8) of Rule 0400-18-01-.02. Owners and/or operators must begin meeting subitem II of this item and conduct a test within 30 days of discontinuing periodic monitoring of this equipment; or

II. The containment sumps used for interstitial monitoring of piping which are single walled or double walled with a dry interstice and periodically monitored are tested at least once every three years to ensure the equipment is liquid tight by using vacuum, pressure, or liquid testing in accordance with one of the following criteria:

A. Requirements developed by the manufacturer (Note: Owners and/or operators may use this option only if the manufacturer has developed requirements);

B. Code of practice developed by a nationally recognized association or independent testing laboratory;

C. Guidance provided by the Division; or

D. Requirements determined by the Division to be no less protective of human health and the environment than the options listed in sections A. and B. of this subitem.

III. Containment sumps which are double walled and constructed so that the inner and outer walls are continuously monitored by interstitial sensors using brine solution or vacuum do not require testing,

(v) When electronic sensors are used to comply with this subparagraph in secondarily contained piping systems, sensors must be installed in every sump and must be placed at the lowest point in the sump and tested for proper operation at least once per year.

2. Reserved.