Leak Detection

Leak Detection. §280.40 General requirements for all UST systems. (a) Owners and operators of new and existing UST systems must provide a method, or combination of methods, of leak detection that: (1) Can detect a leak from any portion of the tank and the connected underground piping and ancillary equipment that routinely contains product; (2) Is installed, calibrated, operated, and maintained in accordance with the manufacturer's instructions and any applicable code of practice listed in §280.13, including routine maintenance and service checks for operability or running condition; (3) Beginning on [three years after effective date of rule], is operated and maintained, and electronic and mechanical components are tested for proper operation. The leak detection equipment shall be tested for proper operation in accordance with one of the following: manufacturer’s instructions; a code of practice developed by a nationally recognized association or independent testing laboratory; or requirements determined by MDEQ to be no less protective of human health and the environment than the two options listed above. A test of the proper operation must be performed at least every 12 months 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 proper placement; remove any 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 § 280.44(a) by simulating a leak; (iv) Vacuum pumps and pressure gauges: ensure proper communication with sensors and controller; and (v) Hand-held electronic sampling equipment associated with groundwater and vapor monitoring: ensure proper operation: and (4) Meets the performance requirements in §280.43, §280.44, §280.45, or Rule 2.10 with any performance claims and their manner of determination described in writing by the equipment manufacturer or installer. In addition, methods used must be capable of detecting the leak rate or quantity specified for that method in the corresponding section of the rule with a probability of detection of 0.95 and a probability of false alarm of 0.05. (b) When a leak detection method operated in accordance with the performance standards in §280.43, §280.44, §280.45, or Rule 2.10 indicates a leak may have occurred, owners and operators must notify the MDEQ in accordance with Rule 2.5. (c) Any UST system that can not apply a method of leak detection that complies with the requirements of this rule must complete the closure procedures in rule 2.7. §280.41 Requirements for petroleum UST systems. Owners and operators of petroleum UST systems must provide leak detection for tanks, piping, and ancillary equipment within secondary containment sumps as follows: (a) Tanks. Tanks installed on or after October 1, 2008, must be monitored at least every 30 days for leaks in accordance with §280.43(g). Tanks installed before October 1, 2008, must be monitored at least every 30 days for leaks using one of the methods listed in §280.43 (d) through (h) except that: (1) UST systems that meet the performance standards in §280.20 or §280.21, and the monthly inventory control requirements in §280.43 (a) or (b), may use tank tightness testing (conducted in accordance with §280.43(c)) at least every 5 years until December 22, 1998, or until 10 years after the tank is installed or upgraded under §280.21(b), whichever is later; (2) Tanks with capacity of 550 gallons or less may use weekly tank gauging (conducted in accordance with §280.43(b)). (b) Piping. Underground piping that routinely contains regulated substances must be monitored for leaks in a manner that meets one of the following requirements: (1) Pressurized piping. Underground piping that conveys regulated substances under pressure must be equipped with an automatic line leak detector conducted in accordance with §280.44(a) except for life safety/critical function UST systems, in which case, an alternative method of leak detection must be approved by MDEQ; and (i) Pressurized piping installed before October 1, 2008, must have an annual line tightness test conducted in accordance with §280.44(b) or have monthly monitoring conducted in accordance with §280.44(c) or §280.44(d). (ii) Pressurized piping installed on or after October 1, 2008, must be monitored at least once every 30 days for leaks in accordance with §280.44(c). (2) Suction piping. Underground piping that conveys regulated substances under suction must: (i) Have a line tightness test conducted at least every 3 years and in accordance with §280.44(b), or use a monthly monitoring method conducted in accordance with §280.44(c) or §280.44(d) if it was installed before October 1, 2008. No release detection is required for suction piping that is designed and constructed to meet the following standards: (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 located directly below and as close as practical to the suction pump; and (E) A method is provided that allows compliance with paragraphs (b)(2)(iii) (B)-(D) of this rule to be readily determined. (ii) Must be monitored at least every 30 days for leaks in accordance with §280.44(c) if it was installed on or after October 1, 2008. (c) Ancillary equipment in secondary containment sumps. Ancillary equipment within secondary containment sumps where the containment sumps were installed on or after October 1, 2008, must be monitored at least every 30 day for leaks or ingress of water in accordance with §280.45. §280.42 Requirements for hazardous substance UST systems. Owners and operators of hazardous substance UST systems must provide leak detection that meets the following requirements: (a) Leak detection at existing UST systems must meet the requirements for petroleum UST systems in §280.41. By December 22, 1998, all existing hazardous substance UST systems must meet the leak detection requirements for new systems in paragraph (b) of this rule. (b) Leak detection at new hazardous substance UST systems must meet the following requirements: (1) Secondary containment systems must be designed, constructed and installed to: (i) Contain regulated substances leaked from the tank system until they are detected and removed; (ii) Prevent the release of regulated substances to the environment at any time during the operational life of the UST system; and (iii)Be checked for evidence of a leak at least every 30 days. Note: The provisions of 40 CFR 265.193, Containment and Detection of Releases, may be used to comply with these requirements. (2) Double-walled tanks must be designed, constructed, and installed to: (i) Contain a leak from any portion of the inner tank within the outer wall; (ii) Detect the failure of the inner wall. (3) External liners (including vaults) must be designed, constructed, and installed to: (i) Contain 100 percent of the capacity of the largest tank within its boundary; (ii) Prevent the interference of precipitation or ground-water intrusion with the ability to contain or detect a leak of regulated substances; and (iii)Surround the tank completely (i.e., it is capable of preventing lateral as well as vertical migration of regulated substances). (4) Underground piping must be equipped with secondary containment that satisfies the requirements of paragraph (b)(1) of this rule. In addition, underground piping that conveys regulated substances under pressure must be equipped with an automatic line leak detector in accordance with §280.44(a). (5) Other methods of leak detection may be used if owners and operators: (i) Demonstrate to the MDEQ that an alternate method can detect a release of the stored substance as effectively as any of the methods allowed in §280.43(b) through (h) can detect a release of petroleum; (ii) Provide information to the MDEQ on effective corrective action technologies, health risks, and chemical and physical properties of the stored substance, and the characteristics of the UST site; and, (iii) Obtain approval from the MDEQ to use the alternate release detection method before the installation and operation of the new UST system. §280.43 Methods of leak detection for tanks. Each method of leak detection for tanks used to meet the requirements of §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 leak of at least 1.0 percent 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 each operating day; (2) The equipment used is 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) 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 one 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; and (6) The measurement of any water level in the bottom of the tank is made to the nearest one- eighth of an inch at least once a month. (b) Manual tank gauging. Manual tank gauging must meet 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 table below during which no liquid is added to or removed from the tank; (2) Level measurements are based on an average of two 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 one-eighth of an inch; (4) A leak is suspected and subject to the requirements of Rule 2.5 if the variation between beginning and ending measurements exceeds the weekly or monthly standards in the following table: Nominal tank capacity Minimum Duration Weekly standard (one test) Monthly standard (average of four tests) 550 gallons or less 36 hours 10 gallons 5 gallons. 551-1,000 gallons (when tank diameter is 64 inches) 44 hours 9 gallons 551-1,000 gallons (when tank diameter is 48 inches) 58 hours 12 gallons 551-1,000 gallons 36 hours 13 gallons 7 gallons. 1,001-2,000 gallons 36 hours 26 gallons 13 gallons. (5) Only tanks of 550 gallons or less nominal capacity may use this as the sole method of leak detection. Tanks of 551 to 2,000 gallons may use this method in place of manual inventory control in §280.43(a). Tanks of greater than 2,000 gallons nominal capacity may not use this method to meet the requirements of this rule. (c) Tank tightness testing. Tank tightness testing (or another test of equivalent performance) must 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 contraction of the product, vapor pockets, tank deformation, evaporation or condensation, and the location of the water table. (d) Automatic tank gauging. Equipment for automatic tank gauging that tests for the loss of product must meet the following requirements: (1) 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. The equipment must be capable of visual or audible alarms and the equipment must be capable of printing the completed 0.2 gallon per hour leak rate test; and (2) The equipment is inspected for proper operation at least once every 12 months. The inspection must be conducted in accordance with the manufacturer's periodic maintenance specifications and any applicable code of practice listed in §280.13. (3) The test must be performed with the system operating in one of the following modes: (i) In-tank static testing conducted at least once every 30 days; or (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. (e) Vapor monitoring. Testing or monitoring for vapors within the soil gas of the excavation zone must meet the following requirements: (1) The materials used as backfill are sufficiently porous (e.g., gravel, sand, crushed rock) to readily allow diffusion of vapors from releases into the excavation area; (2) The stored regulated substance, or a tracer compound placed in the tank system, is sufficiently volatile (e.g., 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 ground water, 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 paragraphs (e) (1) through (4) of this rule 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 product and (7) Monitoring wells are clearly marked and secured to avoid unauthorized access and tampering. (f) Ground-water monitoring. Testing or monitoring for liquids on the ground water must meet the following requirements: (1) The regulated substance stored is immiscible in water and has a specific gravity of less than one; (2) Ground water is never more than 20 feet from the ground surface and the hydraulic conductivity of the soil(s) between the UST system and the monitoring wells or devices is not less than 0.01 cm/sec (e.g., the soil should consist of gravels, 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 ground-water conditions; (4) Monitoring wells shall be sealed from the ground surface to the top of the filter pack; (5) Monitoring wells or devices intercept the excavation zone or are as close to it as is technically feasible; (6) The continuous monitoring devices or manual methods used can detect the presence of at least one-eighth of an inch of free product on top of the ground water 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 paragraphs (f) (1) through (5) of this rule 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; and (8) Monitoring wells are clearly marked and secured to avoid unauthorized access and tampering. (g) Interstitial monitoring. Monitoring of the space between the inner (primary) and the outer (secondary) tank walls may be used, but only if the system is designed, constructed and installed to meet the following requirements: (1) The sampling or testing method can detect a release from any portion of the tank that routinely contains product; (2) The sampling or testing method can detect ingress of external fluids (groundwater or other fluids not intended as monitoring fluids) into the interstice; (3) Records must be maintained that show the interstice has been checked at least every 30 days for evidence of a leak or ingress of external fluids; (i) If the interstice is monitored continuously, records must document that the electronic device monitoring the interstice is in communication with the control console at least monthly; (ii) If the interstice is monitored continuously, records must document the alarm history and provide the response action taken, appropriate reporting (if applicable) and reconciliation of each alarm; (iii)Any electronic device that monitors the interstice must be tested at least once every 12 months for proper function. The functionality test must simulate a leak and be in accordance with the manufacturer's specifications and any applicable industry code or recommended practice listed in §280.13; and (4) Any regulated substance that enters the interstice must be removed within 24 hours of discovery or another time frame determined by the MDEQ to be reasonable. (h) Other methods. Any other type of leak detection method, or combination of methods, can be used if: (1) It can detect a 0.2 gallon per hour leak rate or a release of 150 gallons within a month with a probability of detection of 0.95 and a probability of false alarm of 0.05; or (2) The MDEQ may approve another method if the owner and operator can demonstrate that the method can detect a release as effectively as any of the methods allowed in paragraphs (c) through (h) of this rule. In comparing methods, the MDEQ shall consider the size of leak that the method can detect and the frequency and reliability with which it can be detected. If the method is approved, the owner and operator must comply with any conditions imposed by the MDEQ on its use to ensure the protection of human health and the environment. §280.44 Methods of leak detection for piping. Each method of leak detection for piping used to meet the requirements of §280.41 must 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 regulated substances through piping or triggering an audible or visual alarm may be used only if they detect leaks of 3 gallons per hour at 10 pounds per square inch line pressure within 1 hour. Testing must be performed in accordance with the following requirements: (1) Frequency. (i) Automatic line leak detectors installed on or after October 1, 2008, must be tested in accordance with the requirements of this rule at startup to verify proper operation and at least once every 12 months thereafter. (ii) Automatic line leak detectors installed before October I, 2008, must be tested in accordance with the requirements of this rule by no later than October 1, 2009, and at least once every 12 months thereafter. (2) Criteria. All testing of automatic line leak detectors must be conducted in accordance with the manufacturer's specifications and any applicable code of practice listed in §280.13 and (i) Involve the simulation of a leak in the piping at the dispenser that is at the highest elevation above the submersible pump. If there is no change in elevation, the test must be conducted at the dispenser that is the furthest away from the submersible pump; (ii) Be conducted with the leak detector installed in the system as it normally would be during operation; (iii)Verify that the leak detector is capable of detecting a leak equivalent to 3 gallons per hour at 10 pounds per square inch line pressure within 1 hour; and (iv) Be conducted finitely and the test results reported quantitatively. (3) Records. A written record documenting the testing of automatic line leak detectors must be maintained (in accordance with §280.35) to demonstrate compliance with this section. These records must provide the results of the last two (2) tests required in this section. (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 and the test is conducted in accordance with manufacturer specifications or other recommended code of practice. (c) Interstitial monitoring. Monitoring of the space between the inner (primary) and the outer (secondary) pipe walls may be used, but only if the system is designed, constructed and installed to meet the following requirements: (1) The sampling or testing method can detect a leak from any portion of the pipe that routinely contains product; (2) The sampling or testing method can detect ingress of water or other external fluids into the interstice; (3) Records must be maintained that show the interstice has been checked at least every 30 days for evidence of a leak or ingress of external fluids; (i) If the interstice is monitored continuously, records must document that the electronic device monitoring the interstice is in communication with the control console at least monthly; (ii) If the interstice is monitored continuously, records must document the alarm history and provide the appropriate reporting (if applicable) and reconciliation of each alarm; (iii)Any electronic device that monitors the interstice must be tested at least once every 12 months for proper function. The functionality test must be in accordance with the manufacturer's specifications and any applicable industry code or recommended practice listed in §280.13. The functionality test must simulate a leak; and (4) Any regulated substance that enters the interstice must be removed within 24 hours of discovery or another time frame determined by the MDEQ to be reasonable. (d) Applicable tank methods. Any of the methods in §280.43 (e), (0 or (h) may be used if they are designed to detect a leak from any portion of the underground piping that routinely contains regulated substances. § 280.45 Methods of leak detection for ancillary equipment within secondary containment sumps Each method of leak detection for ancillary equipment within secondary containment sumps used to meet the requirements of §280.31 and §280.41 must be conducted in accordance with the following: (a) Visual Monitoring. Testing or monitoring for liquids in the containment sump or in the interstice of a double walled containment sump must meet the following requirements: (1) Records must be maintained that show the containment sump or the interstice of a double walled containment sump has been checked at least every 30 days for evidence of a leak or ingress of external fluids (2) Once measurements have been recorded, any fluids in the containment sumps shall be removed and properly dispose (b) Electronic Monitoring. Testing or monitoring for liquids in the containment sump must meet the following requirements: (1) The electronic sensors must be securely mounted permanently within the sump to prevent tampering, removal, or adjustment of the sensor (2) The electronic sensors must be placed no more than 1 inch off the bottom of the containment sump § 280.46 Leak detection recordkeeping. All UST system owners and operators must maintain records in accordance with §280.35 demonstrating compliance with all applicable requirements of this rule. These records must include the following: (a) All written performance claims pertaining to any leak detection system used, and the manner in which these claims have been justified or tested by the equipment manufacturer or installer, must be maintained for 5 years, or for another reasonable period of time determined by the MDEQ, from the date of installation; (b) The results of any sampling, testing, or monitoring must be maintained for at least 1 year, or for another reasonable period of time determined by the MDEQ, except that the results of tank tightness testing conducted in accordance with §280.43(c) must be retained until the next test is conducted; and (c) The results of annual operation tests conducted in accordance with §280.40(a)(3) must be maintained for three years. At a minimum, the results must list each component tested, indicate whether each component tested meets criteria in § 280.40(a)(3) or needs to have action taken, and describe any action taken to correct an issue; (d) Written documentation of all calibration, maintenance, and repair of leak detection equipment permanently located on-site must be maintained for at least one year after the servicing work is completed, or for another reasonable time period determined by the MDEQ. Any schedules of required calibration and maintenance provided by the leak detection equipment manufacturer must be retained for 5 years from the date of installation.