Section 93.515. Leak detection methods.

 

(1)   General.

(a) Leak detection methods for tank systems shall meet the requirements of this section.

(b) The leak detection test information reports submitted to the department, or maintained on site as required in s. ATCP 93.500 (9) , shall include at least all of the following:

1. Site information including the name of the business, the street address, and the municipality in which the site is located.

2. Tank system information including the department-assigned tank identification number, the site identification number designated by the owner or operator, the tank capacity, the product in the tank, the type of pipe system, and whether there are pipe manifolds in the tank system.

3. Test method information including the name of the method or equipment used, the material approval number as issued under s. ATCP 93.130 , the date the test was performed, the threshold value used to declare a leak, the rate of volumetric change, whether the final result was a pass or fail, and the name and certification of the technician performing the test.

(2)   Inventory control.

(a) General methodology . Inventory control that is used as the leak detection method shall be conducted in accordance with API 1621 and with this subsection.

(b) Prescriptive requirements . Product inventory control shall be conducted monthly and reconciled to detect a leak rate of at least 0.5 percent of throughput on a monthly basis, in the following manner:

1. Inventory volume measurements for inputs, withdrawals, and the amount still remaining in the tank shall be recorded each operating day.

2. The equipment used shall be capable of measuring the level of product over the full range of the tank's height, to the nearest one-eighth of an inch.

3.

a. The inputs shall be reconciled with delivery receipts by measurement of the tank inventory volume before and after delivery.

b. Where tanks are interconnected by a manifold, reconciliation may address all of the interconnected tanks as a group rather than as individual tanks.

4. The measurement of any water level in the bottom of the tank shall be electronically or manually gauged to the nearest one-eighth of an inch at least once a month and recorded.

(c) Product losses . Tank systems that exceed the losses allowed under par. (b) for 2 consecutive months shall follow the requirements in ss. ATCP 93.575 to 93.585 for assessing and responding to a release.

(d) Precision tightness test. A precision tightness test shall be performed within 10 business days of notification from the authorized agent or the department for any of the following reasons:

1. Failure to provide monthly inventory control data for the past 12 months.

2. Incomplete or inconsistent data entry reflected during any 2 months of data entry out of the most recent 3 months of inventory control record keeping.

(3)   Manual tank gauging.

(a) Where allowed .

1. Manual tank gauging may be used as the sole method of leak detection for tanks that have a capacity of 1,000 gallons or less, for the life of the tank.

2. For tanks that have a capacity of more than 1000 gallons, to 2,000 gallons, manual tank gauging may be used if all of the following conditions are met:

a. The tank system has a precision tightness test performed in accordance with sub. (4) at least once every 5 years.

b. The tank is less than 10 years old.

c. The piping either receives an annual precision tightness test or has electronic line leak detection testing, and this tightness test or leak detection testing is performed in accordance with the capabilities specified in s. ATCP 93.130 (3) (b) .

3. Tanks which have a capacity of more than 1000 gallons, to 2,000 gallons and which are more than 10 years old shall be provided with monthly monitoring in accordance with sub. (5) , (6) or (7) .

4. Tanks that have a capacity of more than 2,000 gallons may not use manual tank gauging as the method of required leak detection.

(b) Manual tank gauging procedures . Manual tank gauging shall meet all of the following requirements:

1. Liquid level measurements shall be taken with a gauge stick that is marked to measure the liquid to the nearest one-eighth of an inch over the full range of the tank's height.

2. Tank liquid level measurements shall be taken at the beginning and ending of the test duration periods given in Table 93.515, during which no liquid may be added to or removed from the tank, and shall be based on the average of 2 stick readings taken at both the beginning and ending of the period.

3. A leak is suspected and subject to the requirements of ss. ATCP 93.575 to 93.585 if the variation between beginning and ending measurements exceeds the weekly or monthly standards in Table 93.515.

(4)   Precision tightness testing.

(a) Precision tightness testing shall be conducted in one of the following ways:

1. By a certified tank system tightness tester, using methods approved under s. ATCP 93.130 to perform precision tightness testing for tanks or piping.

2. With permanently installed leak detection equipment as approved under s. ATCP 93.130 to perform precision tightness testing for tanks or piping.

(b) Where a certified tank system tightness tester is used, the tester shall include the date and the beginning and end times in the test results report.

(5)   Automatic tank gauging. Automatic tank gauging shall meet all of the following requirements:

(a)

1. No more than 30 days may elapse between monthly monitoring tests using an automatic tank gauge.

2. Monthly monitoring tests shall have the capabilities specified in s. ATCP 93.130 (3) (b) .

3. An automatic tank gauge shall be placed in the center of the tank and no closer than 24 inches from the fill pipe and the submersible pump, unless approved otherwise by the department.

(b) Automatic tank gauges shall be provided with a printer that provides at least all of the following information:

1. The starting date and time and ending date and time of the test.

2. The volume of liquid in the tank during the test.

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

4. The specific identification of the tank and any associated piping that is being tested.

(6)   Statistical inventory reconciliation.

(a) Operators using statistical inventory reconciliation (SIR) as the primary method of leak detection shall have in effect a process to submit their data to the vendor within 4 business days of the end of the monthly reporting period.

(b) The daily tank product inventory records shall be maintained current and be maintained on site.

(c) The SIR vendor shall analyze the data and supply a summary report to the operator on a monthly basis.

(d) The SIR vendor shall return the summary report to the submitter within 10 business days after the postmark on the submittal.

(e) 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 release.

(f) Operators who receive summary reports that indicate either a failure or inconclusive results, or 1 of each, for 2 out of any 3 consecutive months shall have a precision tightness test performed on the tank system within 7 calendar days of receipt of the report.

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

(h) Before changing from another method of leak detection to statistical inventory reconciliation, the operator shall provide the department with proof of a precision tightness test completed within the previous 12 months showing the tank system to be 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 wall in any portion of the tank that routinely contains product.

(c) Systems with internally fitted liners .

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.

(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 . 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 1 hour.

(c) Line tightness testing .

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

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) 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, except as provided in subd. 4.

4. A leak shall be introduced to the line system to prove the functionality of the electronic line leak detector unless the manufacturer has an alternate approved or equivalent method for testing whether the detector is functioning as intended by the manufacturer. This testing shall be conducted annually by an individual who has no financial interest in the facility and who is certified by the manufacturer to perform the testing, and it shall include all of the following elements:

a. Review of the test diagnostics for a 3 and 0.2 gallon per hour leak test and the history reports for the leak detector showing monthly leak tests.

b. Verification that the programming parameters are correctly set.

c. Verification that the leak detector is producing normal pump-on pressures, by activating a 3 gallon per hour test from the tank monitor console.

d. Verification that electrical wiring and connections have not deteriorated.

e. Verification that associated sensors are functioning as intended.

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

CR 07-029 : cr. Register November 2008 No. 635 , eff. 2-1-09; CR 09-017 : am. (2) (b) 3. b., r. (5) (b) and (c), renum. (5) (d) and (6) (b) to (g) to be (5) (b) and (6) (c) to (h), cr. (6) (b) Register July 2009 No. 643 , eff. 8-1-09; correction in (1) (b) (intro.), 3., (2) (c), (3) (a) 2. c., (b) 2., 3., (4) (a) 1., 2., (5) (a) 2., (6) (e), (8) (a), (c) 3., (9) made under s. 13.92 (4) (b) 7. , Stats., Register December 2011 No. 672 ; corrections in (1) (b) (intro.), 3., (2) (c), (3) (a) 2. c., (b) 2., 3., (4) (a) 1., 2., (5) (a) 2., (6) (e), (8) (a), (c) 3., (9) made under s. 13.92 (4) (b) 7. , Stats., Register October 2013 No. 694 ; CR 16-012 : am. (2) (d) 2. Register August 2016 No. 728 , eff. 9-1-16.

Note

A leak rate of 0.5 percent is equal to 5 gallons out of every 1000 gallons of throughput. Microsoft Windows NT 6.1.7601 Service Pack 1 Table 93.515
Test Duration and Standards - See PDF for table Microsoft Windows NT 6.1.7601 Service Pack 1 1 Requires precision tightness testing every 5 years. This method is only allowed until the tank is 10 years old. Microsoft Windows NT 6.1.7601 Service Pack 1