Chapter NR 661

NR 661.1084 NR 661.1084 Standards: tanks.

NR 661.1084(1) (1) The provisions of this section apply to the control of air pollutant emissions from tanks for which s. NR 661.1082 (2) references the use of this section for such air emission control.

NR 661.1084(2) (2) The remanufacturer or other person that stores or treats the hazardous secondary material shall control air pollutant emissions from each tank subject to this section in accordance with one of the following requirements as applicable:

NR 661.1084(2)(a) (a) For a tank that manages hazardous secondary material that meets all of the conditions specified in subds. 1. to 2., the remanufacturer or other person that stores or treats the hazardous secondary material shall control air pollutant emissions from the tank in accordance with the Tank Level 1 controls specified in sub. (3) or the Tank Level 2 controls specified in sub. (4).

NR 661.1084(2)(a)1. 1. The hazardous secondary material in the tank has a maximum organic vapor pressure less than the maximum organic vapor pressure limit for the tank’s design capacity category as follows:

NR 661.1084(2)(a)1.a. a. For a tank design capacity equal to or greater than 151 m3, the maximum organic vapor pressure limit for the tank is 5.2 kPa.

NR 661.1084(2)(a)1.b. b. For a tank design capacity equal to or greater than 75 m3 but less than 151 m3, the maximum organic vapor pressure limit for the tank is 27.6 kPa.

NR 661.1084(2)(a)1.c. c. For a tank design capacity less than 75 m3, the maximum organic vapor pressure limit for the tank is 76.6 kPa.

NR 661.1084(2)(a)2. 2. The hazardous secondary material in the tank is not heated by the remanufacturer or other person that stores or treats the hazardous secondary material to a temperature that is greater than the temperature at which the maximum organic vapor pressure of the hazardous secondary material is determined for the purpose of complying with subd. 1.

NR 661.1084(2)(b) (b) For a tank that manages hazardous secondary material that does not meet all of the conditions specified in par. (a) 1. and 2., the remanufacturer or other person that stores or treats the hazardous secondary material shall control air pollutant emissions from the tank by using Tank Level 2 controls in accordance with the requirements under sub. (4). An example of a tank required to use Tank Level 2 controls is a tank for which the hazardous secondary material in the tank has a maximum organic vapor pressure that is equal to or greater than the maximum organic vapor pressure limit for the tank’s design capacity category as specified in par. (a) 1.

NR 661.1084(3) (3) A remanufacturer or other person that stores or treats the hazardous secondary material controlling air pollutant emissions from a tank using Tank Level 1 controls shall meet all of the following requirements:

NR 661.1084(3)(a) (a) The remanufacturer or other person that stores or treats that hazardous secondary material shall determine the maximum organic vapor pressure for a hazardous secondary material to be managed in the tank using Tank Level 1 controls before the first time the hazardous secondary material is placed in the tank. The maximum organic vapor pressure shall be determined using the procedures specified in s. NR 661.1083 (3). Thereafter, the remanufacturer or other person that stores or treats the hazardous secondary material shall perform a new determination whenever changes to the hazardous secondary material managed in the tank could potentially cause the maximum organic vapor pressure to increase to a level that is equal to or greater than the maximum organic vapor pressure limit for the tank design capacity category specified in sub. (2) (a) 1., as applicable to the tank.

NR 661.1084(3)(b) (b) The remanufacturer or other person that stores or treats that hazardous secondary material shall equip the tank with a fixed roof designed to meet all of the following specifications:

NR 661.1084(3)(b)1. 1. The fixed roof and its closure devices shall be designed to form a continuous barrier over the entire surface area of the hazardous secondary material in the tank. The fixed roof may be a separate cover installed on the tank, such as a removable cover mounted on an open-top tank, or may be an integral part of the tank structural design, such as a horizontal cylindrical tank equipped with a hatch.

NR 661.1084(3)(b)2. 2. The fixed roof shall be installed in a manner such that there are no visible cracks, holes, gaps, or other open spaces between roof section joints or between the interface of the roof edge and the tank wall.

NR 661.1084(3)(b)3. 3. Each opening in the fixed roof, and any manifold system associated with the fixed roof, shall be any of the following:

NR 661.1084(3)(b)3.a. a. Equipped with a closure device designed to operate such that when the closure device is secured in the closed position there are no visible cracks, holes, gaps, or other open spaces in the closure device or between the perimeter of the opening and the closure device.

NR 661.1084(3)(b)3.b. b. Connected by a closed-vent system that is vented to a control device. The control device shall remove or destroy organics in the vent stream, and shall be operating whenever hazardous secondary material is managed in the tank, except during any of the following periods:

1) During periods when it is necessary to provide access to the tank for performing the activities of subd. 3. b. 2), venting of the vapor headspace underneath the fixed roof to the control device is not required, opening of closure devices is allowed, and removal of the fixed roof is allowed. Following completion of the activity, the remanufacturer or other person that stores or treats the hazardous secondary material shall promptly secure the closure device in the closed position or reinstall the cover, as applicable, and resume operation of the control device.

2) During periods of routine inspection, maintenance, or other activities needed for normal operations, and for removal of accumulated sludge or other residues from the bottom of the tank.

NR 661.1084(3)(b)4. 4. The fixed roof and its closure devices shall be made of suitable materials that will minimize exposure of the hazardous secondary material to the atmosphere, to the extent practical, and will maintain the integrity of the fixed roof and closure devices throughout their intended service life. Factors to be considered when selecting the materials for and designing the fixed roof and closure devices shall include organic vapor permeability; the effects of any contact with the hazardous secondary material or its vapors managed in the tank; the effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the tank on which the fixed roof is installed.

NR 661.1084(3)(c) (c) Whenever a hazardous secondary material is in the tank, the fixed roof shall be installed with each closure device secured in the closed position except as follows:

NR 661.1084(3)(c)1. 1. Opening of closure devices or removal of the fixed roof is allowed at the following times:

NR 661.1084(3)(c)1.a. a. To provide access to the tank for performing routine inspection, maintenance, or other activities needed for normal operations. Examples of such activities include those times when a worker needs to open a port to sample the liquid in the tank, or when a worker needs to open a hatch to maintain or repair equipment. Following completion of the activity, the remanufacturer or other person that stores or treats the hazardous secondary material shall promptly secure the closure device in the closed position or reinstall the cover, as applicable, to the tank.

NR 661.1084(3)(c)1.b. b. To remove accumulated sludge or other residues from the bottom of the tank.

NR 661.1084(3)(c)2. 2. Opening of a spring-loaded pressure-vacuum relief valve, conservation vent, or similar type of pressure relief device that vents to the atmosphere is allowed during normal operations for the purpose of maintaining the tank internal pressure in accordance with the tank design specifications. The device shall be designed to operate with no detectable organic emissions when the device is secured in the closed position. The settings at which the device opens shall be established such that the device remains in the closed position whenever the tank internal pressure is within the internal pressure operating range determined by the remanufacturer or other person that stores or treats the hazardous secondary material based on the tank manufacturer recommendations, applicable regulations, fire protection and prevention codes, standard engineering codes and practices, or other requirements for the safe handling of flammable, ignitable, explosive, reactive, or hazardous materials. Examples of normal operating conditions that may require these devices to open are during those times when the tank internal pressure exceeds the internal pressure operating range for the tank as a result of loading operations or diurnal ambient temperature fluctuations.

NR 661.1084(3)(c)3. 3. Opening of a safety device, as defined in s. NR 661.1081, is allowed at any time conditions require doing so to avoid an unsafe condition.

NR 661.1084(3)(d) (d) The remanufacturer or other person that stores or treats the hazardous secondary material shall inspect the air emission control equipment according to all of the following requirements:

NR 661.1084(3)(d)1. 1. The fixed roof and its closure devices shall be visually inspected by the remanufacturer or other person that stores or treats the hazardous secondary material to check for defects that could result in air pollutant emissions. Defects include visible cracks, holes, or gaps in the roof sections or between the roof and the tank wall; broken, cracked, or otherwise damaged seals or gaskets on closure devices; and broken or missing hatches, access covers, caps, or other closure devices.

NR 661.1084(3)(d)2. 2. The remanufacturer or other person that stores or treats the hazardous secondary material shall perform an initial inspection of the fixed roof and its closure devices on or before the date that the tank becomes subject to this section. Thereafter, the remanufacturer or other person that stores or treats the hazardous secondary material shall perform the inspections at least once every year except under the special conditions provided for in sub. (12).

NR 661.1084(3)(d)3. 3. In the event that a defect is detected, the remanufacturer or other person that stores or treats the hazardous secondary material shall repair the defect in accordance with the requirements under sub. (11).

NR 661.1084(3)(d)4. 4. The remanufacturer or other person that stores or treats the hazardous secondary material shall maintain a record of the inspection in accordance with the requirements specified in s. NR 661.1089 (2).

NR 661.1084(4) (4) The remanufacturer or other person that stores or treats the hazardous secondary material controlling air pollutant emissions from a tank using Tank Level 2 controls shall use one of the following tanks:

NR 661.1084(4)(a) (a) A fixed-roof tank equipped with an internal floating roof in accordance with the requirements specified in sub. (5).

NR 661.1084(4)(b) (b) A tank equipped with an external floating roof in accordance with the requirements specified in sub. (6).

NR 661.1084(4)(c) (c) A tank vented through a closed-vent system to a control device in accordance with the requirements specified in sub. (7).

NR 661.1084(4)(d) (d) A pressure tank designed and operated in accordance with the requirements specified in sub. (8).

NR 661.1084(4)(e) (e) A tank located inside an enclosure that is vented through a closed-vent system to an enclosed combustion control device in accordance with the requirements specified in sub. (9).

NR 661.1084(5) (5) The remanufacturer or other person that stores or treats the hazardous secondary material who controls air pollutant emissions from a tank using a fixed roof with an internal floating roof shall meet the requirements specified in pars. (a) to (c).

NR 661.1084(5)(a) (a) The tank shall be equipped with a fixed roof and an internal floating roof in accordance with all of the following requirements:

NR 661.1084(5)(a)1. 1. The internal floating roof shall be designed to float on the liquid surface except when the floating roof shall be supported by the leg supports.

NR 661.1084(5)(a)2. 2. The internal floating roof shall be equipped with a continuous seal between the wall of the tank and the floating roof edge that meets any of the following requirements:

NR 661.1084(5)(a)2.a. a. A single continuous seal that is either a liquid-mounted seal or a metallic shoe seal, as defined in s. NR 661.1081.

NR 661.1084(5)(a)2.b. b. Two continuous seals mounted one above the other. The lower seal may be a vapor-mounted seal.

NR 661.1084(5)(a)3. 3. The internal floating roof shall meet all of the following specifications:

NR 661.1084(5)(a)3.a. a. Each opening in a noncontact internal floating roof except for automatic bleeder vents, vacuum breaker vents, and the rim space vents shall provide a projection below the liquid surface.

NR 661.1084(5)(a)3.b. b. Each opening in the internal floating roof shall be equipped with a gasketed cover or a gasketed lid except for leg sleeves, automatic bleeder vents, rim space vents, column wells, ladder wells, sample wells, and stub drains.

NR 661.1084(5)(a)3.c. c. Each penetration of the internal floating roof for the purpose of sampling shall have a slit fabric cover that covers at least 90 percent of the opening.

NR 661.1084(5)(a)3.d. d. Each automatic bleeder vent and rim space vent shall be gasketed.

NR 661.1084(5)(a)3.e. e. Each penetration of the internal floating roof that allows for passage of a ladder shall have a gasketed sliding cover.

NR 661.1084(5)(a)3.f. f. Each penetration of the internal floating roof that allows for passage of a column supporting the fixed roof shall have a flexible fabric sleeve seal or a gasketed sliding cover.

NR 661.1084(5)(b) (b) The remanufacturer or other person that stores or treats the hazardous secondary material shall operate the tank in accordance with all of the following requirements:

NR 661.1084(5)(b)1. 1. When the floating roof is resting on the leg supports, the process of filling, emptying, or refilling shall be continuous and shall be completed as soon as practical.

NR 661.1084(5)(b)2. 2. Automatic bleeder vents shall be set closed at all times when the roof is floating, except when the roof is being floated off or is being landed on the leg supports.

NR 661.1084(5)(b)3. 3. Prior to filling the tank, each cover, access hatch, gauge float well or lid on any opening in the internal floating roof shall be bolted or fastened closed, so that there are no visible gaps. Rim space vents shall be set to open only when the internal floating roof is not floating or when the pressure beneath the rim exceeds the manufacturer’s recommended setting.

NR 661.1084(5)(c) (c) The remanufacturer or other person that stores or treats the hazardous secondary material shall inspect the internal floating roof in accordance with all of the following:

NR 661.1084(5)(c)1. 1. The floating roof and its closure devices shall be visually inspected by the remanufacture or other person that stores or treats the hazardous secondary material to check for defects that could result in air pollutant emissions. Defects include conditions in which the internal floating roof is not floating on the surface of the liquid inside the tank; liquid has accumulated on top of the internal floating roof; any portion of the roof seals have detached from the roof rim; holes, tears, or other openings are visible in the seal fabric; the gaskets no longer close off the hazardous secondary material surface from the atmosphere; or the slotted membrane has more than 10 percent open area.

NR 661.1084(5)(c)2. 2. Except as provided in subd. 3., the remanufacturer or other person that stores or treats the hazardous secondary material shall inspect the internal floating roof components using all of the following procedures:

NR 661.1084(5)(c)2.a. a. Visually inspect the internal floating roof components through openings on the fixed-roof, such as manholes and roof hatches, at least once every 12 months after initial fill.

NR 661.1084(5)(c)2.b. b. Visually inspect the internal floating roof, primary seal, secondary seal, if one is in service, gaskets, slotted membranes, and sleeve seals, if any, each time the tank is emptied and degassed and at least every 10 years.

NR 661.1084(5)(c)3. 3. As an alternative to performing the inspections specified in subd. 2. for an internal floating roof equipped with 2 continuous seals mounted one above the other, the remanufacturer or other person that stores or treats the hazardous secondary material may visually inspect the internal floating roof, primary and secondary seals, gaskets, slotted membranes, and sleeve seals, if any, each time the tank is emptied and degassed and at least every 5 years.

NR 661.1084(5)(c)4. 4. Prior to each inspection required under subd. 2. or 3., the remanufacturer or other person that stores or treats the hazardous secondary material shall notify the department in advance to provide the department with the opportunity to have an observer present during the inspection. The remanufacturer or other person that stores or treats the hazardous secondary material shall notify the department of the date and location of the inspection as follows:

NR 661.1084(5)(c)4.a. a. Prior to each visual inspection of an internal floating roof in a tank that has been emptied and degassed, the remanufacturer or other person that stores or treats the hazardous secondary material shall prepare and send written notification so that it is received by the department at least 30 calendar days before refilling the tank except when an inspection is not planned as provided for in subd. 4. b.

NR 661.1084(5)(c)4.b. b. When a visual inspection is not planned and the remanufacturer or other person that stores or treats the hazardous secondary material could not have known about the inspection 30 calendar days before refilling the tank, the remanufacturer or other person that stores or treats the hazardous secondary material shall notify the department as soon as possible, but no later than 7 calendar days before refilling the tank. This notification may be made by telephone and immediately followed by a written explanation for why the inspection is unplanned. Alternatively, written notification, including the explanation for the unplanned inspection, may be sent so that it is received by the department at least 7 calendar days before refilling the tank.

NR 661.1084(5)(c)5. 5. In the event that a defect is detected, the remanufacturer or other person that stores or treats the hazardous secondary material shall repair the defect in accordance with the requirements under sub. (11).

NR 661.1084(5)(c)6. 6. The remanufacturer or other person that stores or treats the hazardous secondary material shall maintain a record of the inspection in accordance with the requirements specified in s. NR 661.1089 (2).

NR 661.1084(5)(d) (d) Safety devices, as defined in s. NR 661.1081, may be installed and operated as necessary on any tank complying with the requirements specified in this subsection.

NR 661.1084(6) (6) The remanufacturer or other person that stores or treats the hazardous secondary material who controls air pollutant emissions from a tank using an external floating roof shall meet the requirements specified in pars. (a) to (c).

NR 661.1084(6)(a) (a) The remanufacturer or other person that stores or treats the hazardous secondary material shall design the external floating roof in accordance with all of the following requirements:

NR 661.1084(6)(a)1. 1. The external floating roof shall be designed to float on the liquid surface except when the floating roof is supported by the leg supports.

NR 661.1084(6)(a)2. 2. The floating roof shall be equipped with 2 continuous seals, one above the other, between the wall of the tank and the roof edge. The lower seal is referred to as the primary seal, and the upper seal is referred to as the secondary seal. The primary seal and secondary seal shall meet the following requirements:

NR 661.1084(6)(a)2.a. a. The primary seal shall be a liquid-mounted seal or a metallic shoe seal, as defined in s. NR 661.1081. The total area of the gaps between the tank wall and the primary seal may not exceed 212 square centimeters per meter of tank diameter, and the width of any portion of these gaps may not exceed 3.8 centimeters. If a metallic shoe seal is used for the primary seal, the metallic shoe seal shall be designed so that one end extends into the liquid in the tank and the other end extends a vertical distance of at least 61 centimeters above the liquid surface.

NR 661.1084(6)(a)2.b. b. The secondary seal shall be mounted above the primary seal and cover the annular space between the floating roof and the wall of the tank. The total area of the gaps between the tank wall and the secondary seal may not exceed 21.2 square centimeters per meter of tank diameter, and the width of any portion of these gaps may not exceed 1.3 centimeters.

NR 661.1084(6)(a)3. 3. The external floating roof shall meet all of the following specifications:

NR 661.1084(6)(a)3.a. a. Except for automatic bleeder vents, vacuum breaker vents, and rim space vents, each opening in a noncontact external floating roof shall provide a projection below the liquid surface.

NR 661.1084(6)(a)3.b. b. Except for automatic bleeder vents, rim space vents, roof drains, and leg sleeves, each opening in the roof shall be equipped with a gasketed cover, seal, or lid.

NR 661.1084(6)(a)3.c. c. Each access hatch and each gauge float well shall be equipped with a cover designed to be bolted or fastened when the cover is secured in the closed position.

NR 661.1084(6)(a)3.d. d. Each automatic bleeder vent and each rim space vent shall be equipped with a gasket.

NR 661.1084(6)(a)3.e. e. Each roof drain that empties into the liquid managed in the tank shall be equipped with a slotted membrane fabric cover that covers at least 90 percent of the area of the opening.

NR 661.1084(6)(a)3.f. f. Each unslotted and slotted guide pole well shall be equipped with a gasketed sliding cover or a flexible fabric sleeve seal.

NR 661.1084(6)(a)3.g. g. Each unslotted guide pole shall be equipped with a gasketed cap on the end of the pole.

NR 661.1084(6)(a)3.h. h. Each slotted guide pole shall be equipped with a gasketed float or other device that closes off the liquid surface from the atmosphere.

NR 661.1084(6)(a)3.i. i. Each gauge hatch and each sample well shall be equipped with a gasketed cover.

NR 661.1084(6)(b) (b) The remanufacturer or other person that stores or treats the hazardous secondary material shall operate the tank in accordance with all of the following requirements:

NR 661.1084(6)(b)1. 1. When the floating roof is resting on the leg supports, the process of filling, emptying, or refilling shall be continuous and shall be completed as soon as practical.

NR 661.1084(6)(b)2. 2. Except for automatic bleeder vents, rim space vents, roof drains, and leg sleeves, each opening in the roof shall be secured and maintained in a closed position at all times except when the closure device must be open for access.

NR 661.1084(6)(b)3. 3. Covers on each access hatch and each gauge float well shall be bolted or fastened when secured in the closed position.

NR 661.1084(6)(b)4. 4. Automatic bleeder vents shall be set closed at all times when the roof is floating, except when the roof is being floated off or is being landed on the leg supports.

NR 661.1084(6)(b)5. 5. Rim space vents shall be set to open only at those times that the roof is being floated off the roof leg supports or when the pressure beneath the rim seal exceeds the manufacturer’s recommended setting.