567—135.5 (455B) Release detection.
	 135.5(1) 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 release detection that:
	 (1) 	 Can detect a release from any portion of the tank and the connected underground piping that routinely contains product;
	 (2) 	 Is installed, calibrated, operated, and maintained in accordance with the manufacturer’s instructions, including routine maintenance and service checks for operability or running condition; and
	 (3) 	 Meets the performance requirements in 135.5(4) or 135.5(5), with any performance claims and their manner of determination described in writing by the equipment manufacturer or installer. In addition, methods conducted in accordance with 135.5(4)“b,” “c,” and “d” and 135.5(5)“b” after December 22, 1990, and 135.5(5)“a” after September 22, 1991, except for methods permanently installed prior to those dates, must be capable of detecting the leak rate or quantity specified for that method with a probability of detection of 0.95 and a probability of false alarm of 0.05.
	  b.   	 When a release detection method operated in accordance with the performance standards in 135.5(4) and 135.5(5) indicates a release may have occurred, owners and operators must notify the department in accordance with rule 135.6(455B).
	  c.   	 Owners and operators of all UST systems must comply with the release detection requirements of this rule by December 22 of the year listed in the following table:

Scheduled for Phase-in of Release Detection	
Year System Was Installed	Year When Release Detection is Required (by December 22 of the Year
Indicated)	
 	1989	1990	1991	1992	1993	
Before 1965 or
Date Unknown	RD	P	 	 	 	
1965-1969	 	P/RD	 	 	 	
1970-1974	 	P	RD	 	 	
1975-1979	 	P	 	RD	 	
1980-1988	 	P	 	 	RD	
New Tanks	Immediately upon installation	 	 	
P = Must begin release detection for all pressurized piping in accordance with 135.5(2)“b”(1).	
RD = Must begin release detection for tanks and suction piping in accordance with 135.5(2)“a,”
135.5(2)“b”(2), and 135.5(3).	
	  d.   	 Any existing UST system that cannot apply a method of release detection that complies with the requirements of this rule must complete the closure procedures in rule 135.15(455B) by the date on which release detection is required for that UST system under paragraph “c.”
	 135.5(2) Requirements for petroleum UST systems. Owners and operators of petroleum UST systems must provide release detection for tanks and piping as follows:
	  a.   	 Tanks. Tanks must be monitored at least every 30 days for releases using one of the methods listed in 135.5(4)“d” to “h” except that:
	 (1) 	 UST systems that meet the performance standards in 135.3(1) or 135.3(2), and the monthly inventory control requirements in 135.5(4)“a” or “b,” may use tank tightness testing (conducted in accordance with 135.5(4)“c”) at least every five years until December 22, 1998, or until ten years after the tank is installed or upgraded under 135.3(2)“b,” whichever is later;
	 (2) 	 UST systems that do not meet the performance standards in 135.3(1) or 135.3(2) may use monthly inventory controls (conducted in accordance with 135.5(4)“a” or “b”) and annual tank tightness testing (conducted in accordance with 135.5(4)“c”) until December 22, 1998, when the tank must be upgraded under 135.3(2) or permanently closed under 135.15(2); and
	 (3) 	 Tanks with capacity of 550 gallons or less may use weekly tank gauging (conducted in accordance with 135.5(4)“b”).
	  b.   	 Piping. Underground piping that routinely contains regulated substances must be monitored for releases in a manner that meets one of the following requirements:
	 (1) 	 Pressurized piping. Underground piping that conveys regulated substances under pressure must:
	  1. 	 Be equipped with an automatic line leak detector conducted in accordance with 135.5(5)“a”; and
	  2. 	 Have an annual line tightness test conducted in accordance with 135.5(5)“b” or have monthly monitoring conducted in accordance with 135.5(5)“c.”
	 (2) 	 Suction piping. Underground piping that conveys regulated substances under suction must either have a line tightness test conducted at least every three years and in accordance with 135.5(5)“b,” or use a monthly monitoring method conducted in accordance with 135.5(5)“c.”  No release detection is required for suction piping that is designed and constructed to meet the following standards:
	  1. 	 The below-grade piping operates at less than atmospheric pressure;
	  2. 	 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;
	  3. 	 Only one check valve is included in each suction line;
	  4. 	 The check valve is located directly below and as close as practical to the suction pump; and
	  5. 	 A method is provided that allows compliance with “2” through “4” to be readily determined.
	 135.5(3) Requirements for hazardous substance UST systems. Owners and operators of hazardous substance UST systems must provide release detection that meets the following requirements:
	  a.   	 Release detection at existing UST systems must meet the requirements for petroleum UST systems in 135.5(2). By December 22, 1998, all existing hazardous substance UST systems must meet the release detection requirements for new systems in paragraph “b” below.
	  b.   	 Release detection at new hazardous substance UST systems must meet the following requirements:
	 (1) 	 Secondary containment systems must be designed, constructed and installed to:
	  1. 	 Contain regulated substances released from the tank system until they are detected and removed;
	  2. 	 Prevent the release of regulated substances to the environment at any time during the operational life of the UST system; and
	  3. 	 Be checked for evidence of a release at least every 30 days.
Note:  The provisions of 40 CFR 265.193, Containment and Detection of Releases, as of September 13, 1988, may be used to comply with these requirements.
	 (2) 	 Double-walled tanks must be designed, constructed, and installed to:
	  1. 	 Contain a release from any portion of the inner tank within the outer wall; and
	  2. 	 Detect the failure of the inner wall.
	 (3) 	 External liners (including vaults) must be designed, constructed, and installed to:
	  1. 	 Contain 100 percent of the capacity of the largest tank within its boundary;
	  2. 	 Prevent the interference of precipitation or groundwater intrusion with the ability to contain or detect a release of regulated substances; and
	  3. 	 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 135.5(3)“b”(1) above (e.g., trench liners, jacketing of double-walled pipe). In addition, underground piping that conveys regulated substances under pressure must be equipped with an automatic line leak detector in accordance with 135.5(5)“a”;
	 (5) 	 Other methods of release detection may be used if owners and operators:
	  1. 	 Demonstrate to the department that an alternate method can detect a release of the stored substance as effectively as any of the methods allowed in 135.5(4)“b” to “h” can detect a release of petroleum;
	  2. 	 Provide information to the department on effective corrective action technologies, health risks, and chemical and physical properties of the stored substance, and the characteristics of the UST site; and
	  3. 	 Obtain approval from the department to use the alternate release detection method before the installation and operation of the new UST system.
	 135.5(4) Methods of release detection for tanks. Each method of release detection for tanks used to meet the requirements of 135.5(2) 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 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 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; and
	 (6) 	 The measurement of any water level in the bottom of the tank is made to the nearest 1/8 of an inch at least once a month.
Note:  Practices described in the American Petroleum Institute Publication 1621, “Recommended Practice for Bulk Liquid Stock Control at Retail Outlets,” may be used, where applicable, as guidance in meeting the requirements of subrule 135.5(4), paragraph “a,” subparagraphs (1) to (6).
	  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 of at least 36 hours 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 1/8 of an inch;
	 (4) 	 A leak is suspected and subject to the requirements of rule 135.6(455B) if the variation between beginning and ending measurements exceeds the weekly or monthly standards in the following table:

Nominal
Tank Capacity	Weekly Standard
(one test)	Monthly Standard
(average of four tests)	
550 gallons or less	10 gallons	5 gallons	
551-1,000 gallons	13 gallons	7 gallons	
1,001-2,000 gallons	26 gallons	13 gallons	
	 (5) 	 Only tanks of 550 gallons or less nominal capacity may use this as the sole method of release detection. Tanks of 551 to 2000 gallons may use the method in place of manual inventory control in 135.5(4)“a.” Tanks of greater than 2000 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 and conducts inventory control 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; and
	 (2) 	 Inventory control (or another test of equivalent performance) is conducted in accordance with the requirements of 135.5(4)“a.”
	  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 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 135.5(4)“e”(1) to (4) 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.   	 Groundwater monitoring. Testing or monitoring for liquids on the groundwater must meet the following requirements:
	 (1) 	 The regulated substance stored is immiscible in water and has a specific gravity of less than 1;
	 (2) 	 Groundwater 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 groundwater 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 1/8 of an inch of free product 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 135.5(4)“f”(1) to (5) 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. Interstitial monitoring between the UST 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:
	 (1) 	 For secondary containment systems, the sampling or testing method must be able to detect a release through the inner wall in any portion of the tank that routinely contains product:
	  1. 	 Continuously, by means of an automatic leak sensing device that signals to the operator the presence of any regulated substance in the interstitial space; or
	  2. 	 Monthly, by means of a procedure capable of detecting the presence of any regulated substance in the interstitial space.
	  3. 	 The interstitial space shall be maintained and kept free of liquid, debris or anything that could interfere with leak detection capabilities.
Note:  The provisions outlined in the Steel Tank Institute’s “Standard for Dual Wall Underground Storage Tanks” may be used as guidance for aspects of the design and construction of underground steel double-walled tanks.
	 (2) 	 For UST systems with a secondary barrier within the excavation zone, the sampling or testing method used can detect a release between the UST system and the secondary barrier:
	  1. 	 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 release to the monitoring point and permit its detection;
	  2. 	 The barrier is compatible with the regulated substance stored so that a release from the UST system will not cause a deterioration of the barrier allowing a release to pass through undetected;
	  3. 	 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;
	  4. 	 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;
	  5. 	 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 such conditions; and
	  6. 	 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 release between the inner wall of the tank and the liner, and the liner is compatible with the substance stored.
	  h.   	 Other methods. Any other type of release 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 department 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” to “h.” In comparing methods, the department shall 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 must comply with any conditions imposed by the department on its use to ensure the protection of human health and the environment.
	 135.5(5) Methods of release detection for piping. Each method of release detection for piping used to meet the requirements of 135.5(2) 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 one hour. An annual test of the operation of the leak detector must be conducted in accordance with the manufacturer’s requirements.
	  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.
	  c.   	 Applicable tank methods. Any of the methods in 135.5(4)“e” through “h” may be used if they are designed to detect a release from any portion of the underground piping that routinely contains regulated substances.
	  d.   	 Interstitial monitoring of secondary containment. Interstitial monitoring may be used for any piping with secondary containment designed for and capable of interstitial monitoring.
	 (1) 	 Leak detection shall be conducted:
	  1. 	 Continously, by means of an automatic leak sensing device that signals to the operator the presence of any regulated substance in the interstitial space or containment sump; or
	  2. 	 Monthly, by means of a procedure capable of detecting the presence of any regulated substance in the interstitial space or containment sump, such as visual inspection.
	 (2) 	 The interstitial space or sump shall be maintained and kept free of water, debris or anything that could interfere with leak detection capabilities.
	 (3) 	 At least every two years, any sump shall be visually inspected for integrity of sides and floor and tightness of piping penetration seals. Any automatic sensing device shall be tested for proper function.
	 135.5(6) Release detection record keeping. All UST system owners and operators must maintain records in accordance with 135.4(5) demonstrating compliance with all applicable requirements of this rule. These records must include the following:
	  a.   	 All written performance claims pertaining to any release 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 five years, or for another reasonable period of time determined by the department, from the date of installation;
	  b.   	 The results of any sampling, testing, or monitoring must be maintained for at least one year, or for another reasonable period of time determined by the department, except that the results of tank tightness testing conducted in accordance with 135.5(4)“c” must be retained until the next test is conducted; and
	  c.   	 Written documentation of all calibration, maintenance, and repair of release 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 department. Any schedules of required calibration and maintenance provided by the release detection equipment manufacturer must be retained for five years from the date of installation.