Wisconsin Legislature: ATCP 93.515(8)

(a) Leak detection methods based on the application of statistical principles to inventory data shall meet the requirements of 40 CFR § 280.43 (h) including:

1. Report a quantitative result with a calculated leak rate;

2. Be capable of detecting a leak rate of 0.2 gallon per hour or a release of 150 gallons within 30 days; and

3. Use a threshold that does not exceed one-half the minimum detectable leak rate.

(b) Tank systems or portions of tank systems using statistical inventory reconciliation as the primary method of leak detection shall be monitored and evaluated for leaks at least every 30 days with a conclusive result of pass or fail within the 30-day monitoring period.

(d) Tank product level measurements shall be recorded using an electronic inventory probe or an automatic tank gauge.

(e) The operator shall have an effective process to submit their data to the vendor according to the vendor requirements for producing an evaluation report within the 30-day monitoring period.

(f) The statistical inventory reconciliation vendor shall analyze the data and supply an evaluation report to the operator within the 30-day monitoring period.

(g) If the result of the 30-day monitoring period is inconclusive or missing, another method of leak detection shall be used to determine a conclusive pass or fail for that monitoring period.

(h) If during the initial 30-day monitoring period, a conclusive result has not been obtained, another method of leak detection shall be used to determine a conclusive pass or fail for that monitoring period.

(i) Operators using statistical inventory reconciliation shall review the vendor summary report within 24 hours of receipt. If the summary report indicates a failure, the operator shall take immediate action in accordance with the requirements in ss. ATCP 93.575 to 93.585 for assessing and responding to a leak or release.

(j) Statistical inventory reconciliation may not be used as a method of precision tightness testing.

(L) Before changing from another method of leak detection to statistical inventory reconciliation, the operator shall provide the department with proof that precision testing was performed in accordance with sub. (4) within the previous 12 months, showing the tank system to be liquid-tight.

(7) Interstitial monitoring. Interstitial monitoring between an underground tank system and a secondary barrier immediately around it may be used only if the system is installed and maintained to detect a leak from any portion of the tank that could contain product, and the system meets one of the following requirements:

(a) System testing. Post-installation testing shall be performed on the interstitial monitoring system to verify that the system operates in accordance with the manufacturer’s specifications.

(b) Double-walled systems. For double-walled systems, the sampling or testing method shall be capable of detecting a leak through the inner or outer wall in any portion of the tank or piping that routinely contains product.

1. For tank systems with an internally fitted liner, a monitoring system shall be installed that is capable of detecting a leak between the inner wall of the tank and the liner.

2. The liner shall be chemically compatible with the substance stored.

(d) Systems with a barrier in the excavation zone. Systems with a secondary barrier within the excavation zone shall meet all of the following requirements:

1. The testing method shall be capable of detecting a leak between the system and the secondary barrier.

2. The secondary barrier around the system shall consist of manufactured material which is impermeable to at least 10-6 cm/sec for the regulated substance stored, and which will direct a leak to the monitoring point, to be detected.

3. The liner shall be chemically compatible with the substance stored.

4. For cathodically protected tanks, the secondary barrier shall be installed so that it does not interfere with the proper operation of the cathodic protection system.

5. The test method shall be designed, installed, and maintained so groundwater, soil moisture, and rainfall do not render the method inoperative, so that a leak could go undetected.

6. The site shall be investigated to ensure that the secondary barrier is always above groundwater and not in a 25-year flood plain, unless the barrier and monitoring designs are for use under such conditions.

7. Monitoring wells shall be clearly marked and secured to avoid unauthorized access and tampering.

(e) Interstitial monitoring sensors. Interstitial monitoring sensors shall be capable of providing an audible or visual alarm in the event of a tank or line interstitial sensor actuation. Manual operator action shall be needed to silence the alarm.

(8) Methods of leak detection for piping.

(a) General. Leak detection for piping shall follow the requirements of s. ATCP 93.510 (4) and this section.

(b) Automatic line leak detectors.

1. Underground piping systems serving a storage tank with a submersible pump or pressurized booster pump shall be provided with an automatic line leak detector that alerts the operator to the presence of a leak by restricting or shutting off flow from the pump, when it detects leaks of 3 gallons per hour at 10 pounds per square inch line pressure within one hour.

2. New or replacement automatic electronic line leak detection shall be provided with a printer that provides at least all of the following information:

a. The date and time of the test.

b. The measured leak rate in gallons per hour and whether this leak rate indicates a pass or a fail.

c. The specific identification of the associated piping or sumps used for interstitial monitoring that are being tested.

3. Automatic electronic line leak detection shall be programmed to provide an audible and visual alarm in the event of a line test failure or if a periodic monthly line test is not performed within a 30-day interval. Manual operator action shall be needed to silence the alarm.

4. Any of the methods in sub. (7) may be used in lieu of complying with subd. 1. if they are designed and approved under s. ATCP 93.130 to detect a leak from any portion of the underground piping that routinely contains product.

1. In addition to the automatic line leak detection required by par. (b), a periodic precision tightness test of piping shall be performed in accordance with sub. (4), except as provided in subds. 2. and 3.

2. Where piping leak detection is installed that has the capability to perform monthly monitoring, a separate precision tightness test is not required.

3. Any of the methods in subs. (6) and (7) may be used in lieu of complying with subd. 1. if they are designed and approved under s. ATCP 93.130 to detect a leak from any portion of the underground piping that routinely contains product.

(d) Interstitial sensors. Sensors used for interstitial line monitoring shall be programmed to provide an audible or visual alarm. Manual operator action shall be needed to silence the alarm. The operator shall respond to the alarm within 30 minutes.

(e) Periodic line leak detection equipment testing.

1. A start-up functionality test of the operation of the leak detector shall be conducted in accordance with the manufacturer’s procedures for testing to the leak thresholds in par. (b) by inducing a physical line leak.

2. A functionality test of the operation of a mechanical line leak detector shall be conducted annually in accordance with the manufacturer’s procedures for testing to the leak thresholds in par. (b) by inducing a physical line leak.

3. A functionality test of the operation of an electronic line leak detector shall be conducted at least annually in accordance with the manufacturer’s procedures for periodic testing to the leak thresholds in par. (b) by inducing a physical line leak.

5. Annual functionality verification shall be recorded on the department’s electronic-mechanical line leak detector annual functionality form, TR-WM-123, and shall be maintained onsite in accordance with s. ATCP 93.500 (9) (a).

(9) Other methods. The department may approve other methods of leak detection in accordance with s. ATCP 93.130.

(10) Ullage testing. Tightness testing of the ullage portion shall be performed in one of the following ways:

(a) As specified in NFPA 30 section 21.5, by or under the direct supervision of a certified installer or tank system tightness tester.

(b) By or under the direct supervision of a certified tank system tightness tester, with leak detection equipment and methods as approved under s. ATCP 93.130 that measure the tightness of the ullage portion.

(11) Ordered conversion of leak detection methodology.

(a) The authorized agent or the department may order an operator, in writing, to terminate the use of a leak detection method and convert to an approved electronic methodology with history-generation capabilities for any of the following reasons:

1. The operator has a history of failing to perform monthly leak detection for a total of 6 months or more during a 24 month period, or for 3 consecutive months.

2. Statistical inventory reconciliation reports reflect pass for a total of 6 months or more during the preceding 24 months, or for 3 consecutive months, and the data points are not consistent with the material approval criteria in s. ATCP 93.130.

3. The operator fails to review monthly leak-detection reports as required by the applicable leak detection method under this section.

4. The operator enters data into an inventory record that is not supported by actual probe-generated data.

(b) The operator shall complete a conversion under par. (a) within 30 days of the date of the order or as determined by the department. Daily inventory verification as specified in s. ATCP 93.503 (2) is acceptable as a temporary monthly leak detection method during the conversion period.

Note: Failure to provide monthly leak detection in accordance with this subsection beyond the 30-day period or compliance date as determined by the department may result in immediate shutdown under s. ATCP 93.115 (3) (a) 2.

History: CR 17-092: cr. Register October 2019 No. 766, eff. 11-1-19; correction in (6) (L), (11) (a) 1., 2. made under s. 35.17, Stats., Register October 2019 No. 766.

ATCP 93.517 Airport hydrant system requirements.

(1) General.

(a) Airport hydrant system installations shall comply with release reporting, response and investigation, closure, financial responsibility and notification requirements in accordance with this section.

(b) New installations shall meet the plan review requirements in accordance with s. ATCP 93.100.

(2) Airport hydrant system plans and requirements.

(a) For new airport hydrant systems, leak detection plans shall be submitted to the department before the system becomes operational in accordance with s. ATCP 93.100.

(b) Fuel hydrant leak detection plans shall include all of the following:

1. A description of the airport hydrant system.

2. A description of the leak detection method used.

Note: A designer of an airport hydrant leak detection system who does not have a financial interest in the airport may be considered to be the independent third party that is required in s. ATCP 93.130 (3) (b) 1. for leak detection methods.

3. A schedule for testing the system.

4. Any limitations of the leak detection method.

5. An action plan in the event a leak is detected.

(c) Owners and operators of underground piping systems associated with airport hydrant systems shall meet leak detection requirements in accordance with s. ATCP 93.510, or use one or a combination of the following alternative methods of release detection:

1. Perform a semiannual or annual tightness test at or above the piping operating pressure in accordance with the following system volume:

a. Fuel systems with less than 50,000 gallons are not to exceed one gallon per hour for semiannual testing or 0.5 gallons for annual testing.

b. Fuel systems with 50,000 to 75,000 gallons are not to exceed 1.5 gallons per hour for semiannual testing or 0.75 gallons for annual testing.

c. Fuel systems with 75,000 to 100,000 gallons are not to exceed 2.0 gallons per hour for semiannual testing or one gallon for annual testing.

d. Fuel systems greater than 100,000 gallons are not to exceed 3.0 gallons per hour for semiannual testing or 1.5 for annual testing.

2. Piping segments not capable of meeting the maximum 3.0 gallon per hour leak rate for the semiannual test may be tested at a leak rate up to 6.0 gallons per hour according to the following schedule:

a. First test, not later than October 13, 2018, airport hydrant systems may use up to a 6.0 gallon per hour leak rate.

b. Second test, between October 13, 2018, and October 13, 2021, airport hydrant systems may use up to a 6.0 gallon per hour leak rate.

c. Third test, between October 13, 2021, and October 13, 2022, airport hydrant systems must use a 3.0 gallon per hour leak rate.

d. Subsequent tests, after October 13, 2022, begin using semiannual or annual line testing according to the maximum leak detection rate in par. (b).

3. Perform inventory control in accordance with s. ATCP 93.515 (2) at least every 30 days that can detect a leak equal to or less than 0.5 percent of flow through; and

4. Perform a line tightness test, conducted in accordance with s. ATCP 93.515 (4), at least every 2 years; or