Mich. Admin. Code R. 29.2125 - Methods of release detection for tanks

Rule 25. Section 280.43 is amended to read as follows:

Section 280.43. Each method of release detection for tanks used to meet the requirements of section 280.41 must be conducted in accordance with the following:

(a) Inventory control. Product inventory control, or another test of equivalent performance, must be conducted monthly to detect a release of not less than 1.0% of flow-through plus 130 gallons on a monthly basis in the following manner:

(1) Inventory volume measurements for regulated substance inputs, withdrawals, and the amount still remaining in the tank are recorded and computed each operating day.

(2) The equipment and tank charts used are capable of measuring the level of product over the full range of the tank's height to the nearest 1/8 of an inch.

(3) The regulated substance inputs are reconciled with delivery receipts by measurement of the tank inventory volume before and after delivery.

(4) Deliveries are made through a drop tube that extends to within 1 foot of the tank bottom.

(5) Product dispensing is metered and recorded within the local standards for meter calibration or an accuracy of 6 cubic inches for every 5 gallons of product withdrawn.

(6) The measurement of any water level in the tank is made to the nearest 1/8 of an inch not less than once a month.

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

(1) Tank liquid level measurements are taken at the beginning and ending of a period using the appropriate minimum duration of test value in the following table during which liquid is not added to or removed from the tank.

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

(3) The equipment used is capable of measuring the level of product over the full range of the tank's height to the nearest 1/8 of an inch.

(4) A leak is suspected and subject to the requirements of subpart E of these rules if the variation between the beginning and ending measurements exceeds the weekly or monthly standards in the following table:

Nominal Tank Capacity	Minimum Duration of Test	Weekly Standard (1 test)	Monthly Standard (average of 4 tests)
550 gallons or less	36 hours	10 gallons	5 gallons
551 to 1,000 gallons (when tank diameter is 64 inches)	44 hours	9 gallons	4 gallons
551 to 1,000 gallons (when tank diameter is 48 inches)	58 hours	12 gallons	6 gallons
551 to 1,000 gallons (also requires periodic tank tightness testing)	36 hours	13 gallons	7 gallons
1,001 to 2,000 gallons (also requires periodic tank tightness testing)	36 hours	26 gallons	13 gallons

(5) Only a tank that has a nominal capacity of 550 gallons or less and tanks with a nominal capacity of 551 to 1,000 gallons that meet the tank diameter criteria in the table in subdivision (b)(4) of this section may use manual tank gauging as the sole method of release detection. A tank that has a nominal capacity of 551 to 2,000 gallons may use manual tank gauging in place of inventory control under subsection (a) of this section. A tank that has a nominal capacity of more than 2,000 gallons nominal capacity shall not use manual tank gauging to meet the requirements of this subpart.

(6) A tank of any capacity that is used for motor vehicle fueling shall not use the manual tank gauging method to meet the requirements of this subpart.

(c) Tank tightness testing. Tank tightness testing, or another test of equivalent performance, shall be capable of detecting a 0.1 gallon-per-hour leak rate from any portion of the tank that routinely contains product while accounting for the effects of thermal expansion or the contraction of the product, vapor pockets, tank deformation, evaporation or condensation, and the location of the water table. Unless a method is evaluated by a third party and certified as capable of testing manifolded tank systems, each tank in a manifolded tank system can be tested only if it can be isolated from all other tanks in the manifolded tank system and the siphons or other liquid transfer devices to the tank being tested are shut off. Testers shall be trained and certified by the manufacturer or vendor of the testing method and the testers names must appear on the qualified testers list provided by the manufacturer or vendor to the department. The department has the authority to disapprove any existing or future testing device or procedure if the requirements of this subsection cannot be met. The department has the authority to prohibit a person from performing tank tightness testing if the requirements of this subsection cannot be met.

(d) Automatic tank gauging.

(1) Equipment for automatic tank gauging that tests for the loss of product and conducts inventory control must meet both of the following requirement:

(i) The automatic product level monitor test can detect a 0.2 gallon-per-hour leak rate from any portion of the tank that routinely contains product.

(ii) Inventory control, or another test of equivalent performance, is conducted in accordance with the requirements of subsection (a) of this section.

(2) The test shall be performed with the system operating in 1 of the following modes:

(i) In-tank static testing conducted at least once every 30 days.

(ii) Continuous in-tank leak detection operating on an uninterrupted basis or operating within a process that allows the system to gather incremental measurements to determine the leak status of the tank at least once every 30 days.

(3) For waste oil UST(s) and a non-motor fueling system of any size that do not meet the criteria of hazardous wastes listed or identified under the provisions of subtitle C of the solid waste disposal act of 1965, title II of Public Law 89-272, as amended, 42 U.S.C. MCL 6921 to 6931 and 6933 to 6939b, automatic tank gauging equipment that tests for the loss of product by mass measurement probes and conducts inventory control is adequate as required by this section if it meets both of the following requirements:

(i) The automatic product level monitor test can detect a 0.2 gallon-per-hour leak rate from any portion of the tank that routinely contains product.

(ii) Manual tank gauging is conducted in accordance with the requirements of subsection (b)(1) and (2) of this section.

(4) Each tank in a manifolded tank system must be provided with its own automatic tank gauging probe that meets the requirements of subdivisions (1) and (2) of this subsection and must be isolated from all other tanks during the testing process.

(e) Vapor monitoring. Prior approval by the department is required for the utilization of vapor monitoring as the primary method of release detection for an UST or the underground piping system, or both, to verify that testing or monitoring for vapors within the soil gas of the excavation zone meet all of the following conditions:

(1) The materials used as backfill are sufficiently porous, for example, gravel, sand, or crushed rock to readily allow diffusion of vapors from releases in the excavation area.

(2) The stored regulated substance, or a tracer compound placed in the tank system, is sufficiently volatile, for example, gasoline, to result in a vapor level that is detectable by the monitoring devices located in the excavation zone in the event of a release from the tank.

(3) The measurement of vapors by the monitoring device is not rendered inoperative by the groundwater, rainfall, or soil moisture or other known interferences so that a release could go undetected for more than 30 days.

(4) The level of background contamination in the excavation zone will not interfere with the method used to detect releases from the tank.

(5) The vapor monitors are designed and operated to detect any significant increase in concentration above background of the regulated substance stored in the tank system, a component or components of that substance, or a tracer compound placed in the tank system.

(6) In the UST excavation zone, the site is assessed to ensure compliance with the requirements in subdivisions (1) to (4) of this subsection and to establish the number and positioning of monitoring wells that will detect releases within the excavation zone from any portion of the tank that routinely contains project.

(7) Monitoring wells are clearly marked and secured to avoid unauthorized access and tampering. A monitoring well shall have a liquid tight cover and not less than 3-foot deep annular seal to prevent surface water runoff and subsurface water infiltration into the monitoring well.

(f) Groundwater monitoring. Prior approval by the department is required for the utilization of groundwater monitoring as the primary method of release detection for an UST or the underground piping system, or both, to verify that testing or monitoring for liquids on the groundwater meets all of the following conditions:

(1) The regulated substance stored is immersible in water and has a specific gravity of less than 1.

(2) Groundwater is not more than 20 feet from the ground surface and the hydraulic conductivity of the soil or soils between the UST system and the monitoring wells or devices is not less than 0.01 cm/sec. The soil shall consist of gravel, coarse to medium sands, coarse silts, or other permeable materials.

(3) The slotted portion of the monitoring well casing must be designed to prevent migration of natural soils or filter pack into the well and to allow entry of regulated substance on the water table into the well under both high and low groundwater conditions.

(4) Monitoring wells are clearly marked and secured to avoid unauthorized access and tampering. A monitoring well shall also have a liquid tight cover to prevent surface water runoff from entering the monitoring well and an annular seal extending from the ground surface to the top of the filter pack. All well construction and abandonment must comply with part 127 of 1978 PA 368, MCL 333.12701 to 333.12771, and rules promulgated under 1978 PA 368.

(5) Monitoring wells or devices intercept the excavation zone or are as close to it as is technically feasible.

(6) The continuous monitoring devices in accordance with subsection (e) of this section or manual methods used through visual or olfactory observation can detect the presence of the regulated substance stored in the tank system, a component or components of the substance, or a tracer compound placed in the tank system. The monitoring device can detect at least 1/8 of an inch of NAPL on top of the groundwater in the monitoring wells.

(7) Within and immediately below the UST system excavation zone, the site is assessed to ensure compliance with the requirements in subdivision (1) to (5) of this subsection and to establish the number and positioning of monitoring wells or devices that will detect releases from any portion of the tank that routinely contains product.

(g) Interstitial monitoring. Interstitial monitoring between the UST system and a secondary barrier immediately around or beneath it must 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 product and also meets 1 of the following requirements:

(1) For double walled UST systems, the sampling or testing method can detect a leak through the inner wall in any portion of the tank that routinely contains product.

(2) For UST systems with a secondary barrier within the excavation zone, the sampling or testing method used can detect a leak between the UST system and the secondary barrier. The secondary barrier shall meet all of the following:

(i) The secondary barrier around or beneath the UST system consists of artificially constructed material that is sufficiently thick and impermeable (at least 10^-6 cm/sec for the regulated substance stored) to direct a leak to the monitoring point and permit its detection.

(ii) The barrier is compatible with the regulated substance stored so that a leak from the UST system will not cause a deterioration of the barrier allowing a release to pass through undetected.

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

(iv) The groundwater, soil moisture, or rainfall will not render the testing or sampling method used inoperative so that a release could go undetected for more than 30 days.

(v) The site is assessed to ensure that the secondary barrier is always above the groundwater and not in a 25-year flood plain, unless the barrier and monitoring designs are for use under these conditions.

(vi) Monitoring wells are clearly marked and secured to avoid unauthorized access and tampering.

(3) 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.

(h) Statistical inventory reconciliation. Release detection methods based on the application of statistical principles to inventory data similar to those described in subsection 280.43(a) shall meet all of the following requirements:

(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.

(3) Use a threshold that does not exceed 1/2 the minimum detectible leak rate.

(i) Other methods. The department may approve another method or combination of methods of monthly monitoring if a person can demonstrate, by clear and convincing evidence, that the method can detect a release as effectively as any of the methods allowed in subsections (c) to (h) of this section. In comparing methods , the department shall consider the size of the release that the method can detect and the frequency and reliability with which it can be detected. A detection capability of 0.2 gallons per hour release rate with a probability of detection of 0.95 and a probability of false alarm of 0.05 will be deemed sufficient to approve a monthly monitoring method. If the method is approved, the owner and operator shall comply with any conditions imposed by the department on the use of the method to ensure the protection of human health and the environment.

Notes

Mich. Admin. Code R. 29.2125

1998-2000 AACS; 2018 MR 21, Eff. 11/14/2018