Wisconsin Administrative Code
Department of Agriculture, Trade and Consumer Protection
ATCP 90-139 - Trade and Consumer Protection
Chapter ATCP 93 - Flammable, Combustible, And Hazardous Liquids
Subchapter V - General UST Storage and Underground Piping
Section ATCP 93.510 - Leak detection requirements

Universal Citation: WI Admin Code § ATCP 93.510

Current through February 24, 2025

(1) GENERAL.

(a) All new and existing underground tank systems used to store regulated substances shall be provided with a method of leak detection that complies with this section and s. ATCP 93.515, except as exempted in par. (d).

(b) The method of leak detection shall be approved in accordance with s. ATCP 93.130.

(c) All monitoring equipment used to satisfy the requirements of this section shall be installed, calibrated, operated, and maintained to perform as originally intended in accordance with the manufacturer's instructions and the department's approval as issued under s. ATCP 93.130.

(d) Leak detection is not required for any of the following tanks:
1. Tanks which have a capacity of less than 1,100 gallons and which are located on farm premises or at private residences.

2. Tanks storing Class IIIB liquids that are neither petroleum nor CERCLA-listed products.

(e) If a tank system exhibits a continuing pattern of failing and then not failing leak detection testing, a precision tightness test shall be performed within 10 business days in accordance with s. ATCP 93.515(4), and if a tank system fails to pass that test, the site shall be assessed for the presence of a release in accordance with ss. ATCP 93.575 to 93.585.

Note: This section primarily addresses the leak detection that is required on a routine, ongoing basis during normal operation of an underground storage tank system. Several other sections of this chapter require additional UST leakage or tightness testing.

(2) ANNUAL EQUIPMENT VERIFICATION.

(a) The following equipment shall be verified by a qualified person every 12 months for the same degree of operability and capability as when the equipment was newly installed using either requirements developed by the manufacturer, or code of practice developed by a nationally recognized association in Table 93.200.
1. Equipment for measuring product levels that is used for manual tank gauging or statistical inventory reconciliation.

2. Automatic tank gauging equipment used for monthly monitoring, statistical inventory reconciliation or precision tightness testing.

3. Interstitial monitoring equipment.

4. Sensors used to detect leaks in tanks, lines or sumps.

5. Overfill prevention equipment automatic high-level alarm at 90 percent tank capacity and automatic overfill prevention shut off device at 95 percent capacity. The automatic overfill prevention device does not have to be removed from the tank if designed to be tested in place by the manufacturer and the manufacturer provides a test procedure that includes verification of operation and shut off level at 95 percent tank capacity.

(b) Under this subsection, a qualified person is a person certified by the equipment manufacturer as being trained in the operational characteristics of the equipment.

(c)
1. Annual monitoring equipment certification shall be made on the department's underground tank system functionality verification form, TR-WM-139, and on the department's electronic-mechanical line leak detector annual functionality form, TR-WM-123, and line test report form, TR-WM-125, if applicable and shall be maintained onsite in accordance with s. ATCP 93.500(9) (a).

2. If all deficiencies found during the equipment verification have not been corrected, the first page of the TR-WM-139 form shall be sent to the department email address on the form within 5 business days of the completion of the verification.

Note: Form TR-WM-123, Electronic/Mechanical Line Leak Detector Annual Functionality, Form TR-WM-125, Line Tightness Test Report, and Form TR-WM-139, Underground Tank System Functionality Verification, are available from the Bureau of Weights and Measures, PO Box 8911, Madison, WI 53708-8911, or at telephone (608) 224-4942, or from the Bureau's Web site at https://datcp.wi.gov/Pages/Programs_Services/PetroleumHazStorageTanks.aspx. See s. ATCP 93.165 for use of alternate forms approved by the department.

(3) LEAK DETECTION FOR TANKS.

(a) General.
1. Tanks shall be monitored at least every 30 days for leaks using one of the methods listed in s. ATCP 93.515, except as provided in subd. 2. and s. ATCP 93.500(1) (a).

2. Tanks installed prior to February 1, 2009, that have a capacity of 1,000 gallons or less may use manual tank gauging conducted in accordance with s. ATCP 93.515(3) as the sole means of leak detection provided it is performed weekly.

Note: Under s. ATCP 93.500(1) (a), continuous electronic interstitial monitoring is generally required for all secondary containment installed on or after February 1, 2009.

(b) Failed tests. If a passing test using monthly monitoring is not achieved, the site shall be assessed for the presence of a release in accordance with ss. ATCP 93.575 to 93.585.

(c) Inconsistent results. The authorized agent or the department may require a precision tightness test to be performed where any of the following events occur:
1. A tank system is accumulating water for no apparent reason.

2. A leak detection method is providing erratic results.

3. A tank system is tested with multiple leak detection methods that show different results.

(d) Inventory control as leak detection. Tank systems installed prior to February 1, 2009, may use monthly inventory control performed in accordance with s. ATCP 93.515(2) as leak detection provided all of the following conditions are met:
1. The tank is 10 years old or less.

2. The tank has precision tank tightness testing performed in accordance with s. ATCP 93.515(4) at least once every 5 years from the date of installation until the tank is 10 years old.

3. The tank system has corrosion protection in accordance with s. ATCP 93.520.

(4) LEAK DETECTION FOR PIPING.

(a) Pressurized piping. Underground piping that conveys regulated substances under pressure shall comply with all of the following requirements:
1. The system shall be equipped with an automatic line leak detector in accordance with s. ATCP 93.515(8) (b).

2. Single-wall piping systems shall have at least one of the following leak detection methods:
a. An annual precision tightness test in accordance with s. ATCP 93.515(4).

b. Monthly monitoring to the 0.2 gallon per hour rate.

3. Double-wall piping systems shall use one of the leak detection methods in subd. 2., or statistical inventory reconciliation, or continuous interstitial monitoring, except as provided in s. ATCP 93.500(1) (a).

Note: Under s. ATCP 93.500(1) (a), continuous electronic interstitial monitoring is generally required for all secondary containment installed on or after February 1, 2009.

4. If a passing test using monthly monitoring is not achieved, the site shall be assessed for the presence of a release in accordance with ss. ATCP 93.575 to 93.585.

(b) Suction piping.
1. Piping which conveys regulated substances under suction and which is not entirely visible shall use one of the following leak detection methods, except as provided in subd. 2.:
a. A precision tightness test performed in accordance with s. ATCP 93.515(4) at least every three years.

b. Interstitial monitoring.

2. Leak detection may be omitted for suction piping that meets all of the following requirements:
a. The below-grade piping operates at less than atmospheric pressure.

b. 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.

c. Only one check valve is included in each suction line.

d. The check valve is visibly located directly below and as close as practical to the suction pump.

e. A method is provided that allows compliance with subd. 2. b. to d. to be readily observed or otherwise determined.

(c) Inventory control as leak detection. Piping connected to a tank using inventory control in accordance with sub. (3) (d) shall comply with one of the following:
1. Pressurized piping shall have leak detection complying with par. (a).

2. Suction piping shall have leak detection complying with par. (b).

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