§ 245.444. Methods of release detection for tanks.
Each method of release detection for tanks used to meet the requirements in § § 245.441 and 245.442 (relating to general requirements for underground storage tank systems; and periodic monitoring requirements for petroleum underground storage tank systems) shall be conducted in accordance with all of the following:
(1) Manual tank gauging. Manual tank gauging shall meet the following requirements:
(i) Tank liquid level measurements are taken at the beginning and ending of a period of at least 36 hours during which no liquid is added to or removed from the tank.
(ii) Level measurements are based on an average of two consecutive stick readings at both the beginning and ending of the period.
(iii) 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.
(iv) A leak is suspected and subject to Subchapter D (relating to corrective action process for owners and operators of storage tanks and storage tank facilities and other responsible parties) if the variation between beginning and ending measurements exceeds the weekly or monthly standards in the following table:
Monthly Minimum Weekly Standard Periodic Nominal Tank Duration Standard (average of) Tightness Capacity of Test (one test) four tests Test Required 550 gallons or less 36 hours 10 gallons 5 gallons No 551—1,000 gallons: 64" diameter tank 44 hours 9 gallons 4 gallons No 551—1,000 gallons: 48" diameter tank 58 hours 12 gallons 6 gallons No 551—1,000 gallons 36 hours 13 gallons 7 gallons Yes (v) Owners and operators of underground storage tanks of greater than 1,000 gallons nominal capacity may not use this method to meet the requirements in this section.
(2) 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.
(3) Automatic tank gauging. Equipment for automatic tank gauging that tests for the loss of product and conducts inventory control must meet one 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) Tank gauges shall be certified by an independent third-party verifying the gauge’s ability to detect the leak rate in subparagraph (i) following EPA evaluation protocol.
(4) Vapor monitoring. Testing or monitoring for vapors within the soil gas of the excavation zone must meet the following requirements:
(i) The materials used as backfill are sufficiently porous—for example, gravel, sand or crushed rock—to readily allow diffusion of vapors from releases into the excavation area.
(ii) 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.
(iii) 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.
(iv) The level of background contamination in the excavation zone will not interfere with the method used to detect releases from the tank.
(v) 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 of that substance or a tracer compound placed in the tank system.
(vi) In the underground storage tank excavation zone, the site is evaluated by a licensed professional under the Engineer, Land Surveyor and Geologist Law (63 P. S. § § 148—158.2) to ensure compliance with subparagraphs (i)—(iv) 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. The written site evaluation report authenticated by the person completing the evaluation must be maintained at the facility for the duration of the leak detection method.
(5) Groundwater monitoring. Testing or monitoring for liquids on the groundwater must meet the following requirements:
(i) The regulated substance stored is immiscible in water and has a specific gravity of less than one.
(ii) Groundwater is never more than 20 feet from the ground surface and the hydraulic conductivity of the soils between the underground storage tank system and the monitoring wells or devices is not less than 0.01 cm/sec—for example, the soil should consist of gravels, coarse to medium sands, coarse silts or other permeable materials.
(iii) The slotted portion of the monitoring well casing shall be designed to prevent migration of natural soils or filter pack into the well and to allow entry of regulated substances on the water table into the well under both high and low groundwater conditions.
(iv) Monitoring wells shall be sealed from the ground surface to the top of the filter pack.
(v) Monitoring wells or devices intercept the excavation zone or are as close to it as is technically feasible.
(vi) The continuous monitoring devices or manual methods used can detect the presence of at least 1/8 of an inch of free product on top of the groundwater in the monitoring wells.
(vii) Within and immediately below the underground storage tank system excavation zone, the site is evaluated by a licensed professional under the Engineer, Land Surveyor and Geologist Law to ensure compliance with subparagraphs (i)—(v) 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. The written site evaluation report authenticated by the person completing the evaluation must be maintained at the facility for the duration of the leak detection method.
(viii) Monitoring wells are clearly marked and secured to avoid unauthorized access and tampering in accordance with § 245.432(b).
(6) Interstitial monitoring. Interstitial monitoring between the underground storage tank system and a secondary barrier immediately around or beneath it may 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 one of the following requirements:
(i) For double-walled underground storage tank systems, the sampling or testing method can detect a release through the inner wall in any portion of the tank that routinely contains product.
(ii) For underground storage tank systems with a secondary barrier within the excavation zone, the sampling or testing method used can detect a release between the underground storage tank system and the secondary barrier.
(A) The secondary barrier around or beneath the underground storage tank 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 release to the monitoring point and permit its detection.
(B) The barrier is compatible with the regulated substance stored so that a release from the underground storage tank system will not cause a deterioration of the barrier allowing a release to pass through undetected.
(C) 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.
(D) 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.
(E) The site is assessed to ensure that the secondary barrier is always above the groundwater and not in a 25-year floodplain, unless the barrier and monitoring designs are for use under these conditions.
(F) Monitoring wells are clearly marked and secured to avoid unauthorized access and tampering in accordance with § 245.432(b).
(iii) For tanks with an internally fitted liner, an automated device can detect a release between the inner wall of the tank and the liner, and the liner is compatible with the substance stored.
(7) Statistical Inventory Reconciliation (SIR). SIR shall meet the performance standards of paragraph (8)(i) for monthly monitoring.
(i) The owner or operator shall follow the instructions of the SIR manufacturer’s protocol.
(ii) A separate report for each tank monitored shall be maintained by the owner or operator in accordance with § 245.446(2) (relating to release detection recordkeeping). Each report shall meet the following requirements:
(A) A valid report shall include the calculated leak rate, positive for out of tank and negative for into tank, minimum detectable leak rate (MDL), leak detection threshold, probability of detection (Pd) and probability of false alarm (Pfa) which the supplied data supports.
(B) A valid report shall also include one of the following test results:
(I) If the calculated leak rate, absolute value, is less than the leak threshold and the MDL is less than or equal to the certified performance standard, the test result is ‘‘pass.’’
(II) If the calculated leak rate, absolute value, is greater than the leak threshold, the test result is ‘‘fail.’’
(III) If the MDL exceeds the certified performance standard and the calculated leak rate is less than the leak threshold, the test result is ‘‘inconclusive.’’ An inconclusive result is considered a suspected leak and shall be investigated in accordance with § 245.304 (relating to investigation and reporting of suspected releases).
(8) Other methods. Other types of release detection methods, or a combination of methods, may be used if the owner or operator can demonstrate to the Department that one of the following exists:
(i) 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.
(ii) It can detect a release as effectively as any of the methods allowed in paragraphs (2)—(7). In comparing methods, the Department will consider the size of release 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 shall comply with conditions imposed by the Department on its use to ensure the protection of human health and the environment.
Source The provisions of this § 245.444 amended November 30, 2001, effective January 1, 2001, 31 Pa.B. 6615; amended November 9, 2007, effective November 10, 2007, 37 Pa.B. 5979; amended December 21, 2018, effective December 22, 2018, 48 Pa.B. 7875. Immediately preceding text appears at serial pages (331083) to (331088).
Cross References This section cited in 25 Pa. Code § 245.31 (relating to underground storage tank system testing requirements); 25 Pa. Code § 245.403 (relating to applicability); 25 Pa. Code § 245.434 (relating to repairs allowed); 25 Pa. Code § 245.437 (relating to periodic testing); 25 Pa. Code § 245.441 (relating to general requirements for underground storage tank systems); 25 Pa. Code § 245.442 (relating to periodic monitoring requirements for petroleum underground storage tank systems); 25 Pa. Code § 245.443 (relating to requirements for hazardous substance underground storage tank systems); 25 Pa. Code § 245.445 (relating to methods of release detection for piping); 25 Pa. Code § 245.446 (relating to release detection recordkeeping); and 25 Pa. Code § 252.3 (relating to scope).
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