Wisconsin Administrative Code, Subchapter CC, Section NR 665.1085 - Standards: tanks | Wisconsin Administrative Code

(1) This section applies to the control of air pollutant emissions from tanks for which s. NR 665.1083(2) references the use of this section for the air emission control.

(2) The owner or operator shall control air pollutant emissions from each tank subject to this section according to one of the following requirements, as applicable:

(a) For a tank that manages hazardous waste that meets all of the following conditions, control air pollutant emissions from the tank according to the Tank Level 1 controls specified in sub. (3) or the Tank Level 2 controls specified in sub. (4):

1. The hazardous waste in the tank has a maximum organic vapor pressure which is less than the maximum organic vapor pressure limit for the tank's design capacity category as follows:

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.

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.

c. For a tank design capacity less than 75 m3, the maximum organic vapor pressure limit for the tank is 76.6 kPa.

2. The hazardous waste in the tank is not heated to a temperature that is greater than the temperature at which the maximum organic vapor pressure of the hazardous waste is determined for the purpose of complying with subd. 1.

3. The hazardous waste in the tank is not treated using a waste stabilization process, as defined in s. NR 665.1081.

(b) For a tank that manages hazardous waste that does not meet all of the conditions in par. (a) 1. to 3., control air pollutant emissions from the tank using Tank Level 2 controls according to sub. (4). Examples of tanks required to use Tank Level 2 controls include a tank used for a waste stabilization process, and a tank for which the hazardous waste 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.

(3) Owners and operators controlling air pollutant emissions from a tank using Tank Level 1 controls shall meet all of the following requirements:

(a) Determine the maximum organic vapor pressure for a hazardous waste to be managed in the tank using Tank Level 1 controls before the first time the hazardous waste is placed in the tank. Determine the maximum organic vapor pressure using the procedures in s. NR 665.1084(3). Thereafter, perform a new determination whenever changes to the hazardous waste 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.

(b) Equip the tank with a fixed roof designed to meet all of the following specifications:

1. Design the fixed roof and its closure devices to form a continuous barrier over the entire surface area of the hazardous waste in the tank. The fixed roof may be a separate cover installed on the tank (e.g., a removable cover mounted on an open-top tank) or may be an integral part of the tank structural design (e.g., a horizontal cylindrical tank equipped with a hatch).

2. Install the fixed roof 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.

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

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.

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 waste is managed in the tank, except as follows:

1) During periods 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. After completing the activity, 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 the removal of accumulated sludge or other residues from the bottom of the tank.

4. Make the fixed roof and its closure devices of suitable materials that will minimize exposure of the hazardous waste 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 consider 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 waste 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.

(c) Whenever a hazardous waste is in the tank, install the fixed roof with each closure device secured in the closed position except as follows:

1. Opening of closure devices or removal of the fixed roof is allowed at the following times:

a. To provide access to the tank for performing routine inspection, maintenance or other activities needed for normal operations. Examples of those 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. After completing the activity, promptly secure the closure device in the closed position or reinstall the cover, as applicable, to the tank.

b. To remove accumulated sludge or other residues from the bottom of the tank.

2. Opening of a spring-loaded pressure-vacuum relief valve, conservation vent or similar type of pressure relief device which vents to the atmosphere is allowed during normal operations for the purpose of maintaining the tank internal pressure according to the tank design specifications. Design the device to operate with no detectable organic emissions when the device is secured in the closed position. Establish the settings at which the device opens such that the device remains in the closed position whenever the tank internal pressure is within the internal pressure operating range determined by the owner or operator based on the tank manufacturer recommendations, applicable rules, 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.

3. Opening of a safety device, as defined in s. NR 665.1081, is allowed at any time conditions require doing so to avoid an unsafe condition.

(d) Inspect the air emission control equipment according to all of the following requirements:

1. Visually inspect the fixed roof and its closure devices to check for defects that could result in air pollutant emissions. Defects include, but are not limited to, 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.

2. 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, perform the inspections at least once every year except under the special conditions provided for in sub. (12).

3. In the event that a defect is detected, repair the defect according to sub. (11).

4. Maintain a record of the inspection according to s. NR 665.1090(2).

(4) Owners and operators controlling air pollutant emissions from a tank using Tank Level 2 controls shall use one of the following tanks:

(a) A fixed-roof tank equipped with an internal floating roof according to sub. (5).

(b) A tank equipped with an external floating roof according to sub. (6).

(c) A tank vented through a closed-vent system to a control device according to sub. (7).

(d) A pressure tank designed and operated according to sub. (8).

(e) A tank located inside an enclosure that is vented through a closed-vent system to an enclosed combustion control device according to sub. (9).

(5) The owner or operator who controls air pollutant emissions from a tank using a fixed-roof with an internal floating roof shall meet pars. (a) to (c).

(a) Equip the tank with a fixed roof and an internal floating roof according to all of the following requirements:

1. Design the internal floating roof to float on the liquid surface except when the floating roof must be supported by the leg supports.

2. Equip the internal floating roof with a continuous seal between the wall of the tank and the floating roof edge that meets any of the following requirements:

a. A single continuous seal that is either a liquid-mounted seal or a metallic shoe seal, as defined in s. NR 665.1081.

b. Two continuous seals mounted one above the other. The lower seal may be a vapor-mounted seal.

3. The internal floating roof shall meet all of the following specifications:

a. Each opening in a non-contact internal floating roof, except for automatic bleeder vents (vacuum breaker vents) and the rim space vents, provides a projection below the liquid surface.

b. Each opening in the internal floating roof is 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.

c. Each penetration of the internal floating roof for the purpose of sampling has a slit fabric cover that covers at least 90 percent of the opening.

d. Each automatic bleeder vent and rim space vent is gasketed.

e. Each penetration of the internal floating roof that allows for passage of a ladder has a gasketed sliding cover.

f. Each penetration of the internal floating roof that allows for passage of a column supporting the fixed roof has a flexible fabric sleeve seal or a gasketed sliding cover.

(b) Operate the tank according to all of the following requirements:

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.

2. Set automatic bleeder vents to 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.

3. Prior to filling the tank, bolt or fasten closed (i.e., no visible gaps) each cover, access hatch, gauge float well or lid on any opening in the internal floating roof. Set rim space vents to open only when the internal floating roof is not floating or when the pressure beneath the rim exceeds the manufacturer's recommended setting.

(c) Inspect the internal floating roof according to all of the following requirements:

1. Visually inspect the floating roof and its closure devices to check for defects that could result in air pollutant emissions. Defects include, but are not limited to, 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 waste surface from the atmosphere or the slotted membrane has more than 10 percent open area.

2. Inspect the internal floating roof components as follows, except as provided in subd. 3.:

a. Visually inspect the internal floating roof components through openings on the fixed-roof (e.g., manholes and roof hatches) at least once every 12 months after initial fill.

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.

3. As an alternative to performing the inspections in subd. 2. for an internal floating roof equipped with 2 continuous seals mounted one above the other, 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.

4. Prior to each inspection required by subd. 2. or 3., notify the department in advance of each inspection to provide the department with the opportunity to have an observer present during the inspection. Notify the department of the date and location of the inspection as follows:

a. Prior to each visual inspection of an internal floating roof in a tank that has been emptied and degassed, prepare and send written notification so that the department receives it at least 30 calendar days before refilling the tank, except when an inspection is not planned as provided for in subd. 4. b.

b. When a visual inspection is not planned and the owner or operator could not have known about the inspection 30 calendar days before refilling the tank, notify the department as soon as possible, but no later than 7 calendar days before refilling the tank. Make this notification by telephone and immediately follow with a written explanation for why the inspection is unplanned. Alternatively, send written notification, including the explanation for the unplanned inspection, so that the department receives it at least 7 calendar days before refilling the tank.

5. In the event that a defect is detected, repair the defect according to sub. (11).

6. Maintain a record of the inspection according to the requirements in s. NR 665.1090(2).

(d) Safety devices, as defined in s. NR 665.1081, may be installed and operated as necessary on any tank complying with this subsection.

(6) The owner or operator who controls air pollutant emissions from a tank using an external floating roof shall meet pars. (a) to (c).

(a) Design the external floating roof according to all of the following requirements:

1. Design the external floating roof to float on the liquid surface except when the floating roof must be supported by the leg supports.

2. Equip the floating roof 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.

a. The primary seal shall be a liquid-mounted seal or a metallic shoe seal, as defined in s. NR 665.1081. The total area of the gaps between the tank wall and the primary seal may not exceed 212 square centimeters (cm2) per meter of tank diameter, and the width of any portion of these gaps may not exceed 3.8 centimeters (cm). If a metallic shoe seal is used for the primary seal, design the metallic shoe seal 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.

b. Mount the secondary seal 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 (cm2) per meter of tank diameter, and the width of any portion of these gaps may not exceed 1.3 centimeters (cm).

3. The external floating roof shall meet all of the following specifications:

a. Except for automatic bleeder vents (vacuum breaker vents) and rim space vents, each opening in a non-contact external floating roof shall project below the liquid surface.

b. Except for automatic bleeder vents, rim space vents, roof drains and leg sleeves, equip each opening in the roof with a gasketed cover, seal or lid.

c. Equip each access hatch and each gauge float well with a cover designed to be bolted or fastened when the cover is secured in the closed position.

d. Equip each automatic bleeder vent and each rim space vent with a gasket.

e. Equip each roof drain that empties into the liquid managed in the tank with a slotted membrane fabric cover that covers at least 90 percent of the area of the opening.

f. Equip each unslotted and slotted guide pole well with a gasketed sliding cover or a flexible fabric sleeve seal.

g. Equip each unslotted guide pole with a gasketed cap on the end of the pole.

h. Equip each slotted guide pole with a gasketed float or other device which closes off the liquid surface from the atmosphere.

i. Equip each gauge hatch and each sample well with a gasketed cover.

(b) Operate the tank according to all of the following requirements:

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.

2. Except for automatic bleeder vents, rim space vents, roof drains and leg sleeves, secure and maintain each opening in the roof in a closed position at all times except when the closure device must be open for access.

3. Bolt or fasten covers on each access hatch and each gauge float well when secured in the closed position.

4. Set closed automatic bleeder vents at all times when the roof is floating, except when the roof is being floated off or is being landed on the leg supports.

5. Set to open rim space vents 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.

6. Secure the cap on the end of each unslotted guide pole in the closed position at all times except when measuring the level of the liquid in the tank or collecting samples of the liquid.

7. Secure the cover on each gauge hatch or sample well in the closed position at all times except when the hatch or well must be opened for access.

8. Both the primary seal and the secondary seal shall completely cover the annular space between the external floating roof and the wall of the tank in a continuous fashion except during inspections.

(c) Inspect the external floating roof according to all of the following procedures:

1. Measure the external floating roof seal gaps according to all of the following requirements:

a. Perform measurements of gaps between the tank wall and the primary seal within 60 calendar days after initial operation of the tank following installation of the floating roof and, thereafter, at least once every 5 years.

b. Perform measurements of gaps between the tank wall and the secondary seal within 60 calendar days after initial operation of the tank following installation of the floating roof and, thereafter, at least once every year.

c. If a tank ceases to hold hazardous waste for a period of one year or more, subsequent introduction of hazardous waste into the tank is an initial operation for the purposes of subd. 1. a. and b.

d. Determine the total surface area of gaps in the primary seal and in the secondary seal individually using the following procedure:

1) Perform the seal gap measurements at one or more floating roof levels when the roof is floating off the roof supports.

2) Measure seal gaps, if any, around the entire perimeter of the floating roof in each place where a 0.32-centimeter (cm) diameter uniform probe passes freely (without forcing or binding against the seal) between the seal and the wall of the tank and measure the circumferential distance of each location.

3) For a seal gap measured under this paragraph, determine the gap surface area using probes of various widths to measure accurately the actual distance from the tank wall to the seal and multiplying each width by its respective circumferential distance.

4) Calculate the total gap area by adding the gap surface areas determined for each identified gap location for the primary seal and the secondary seal individually, and then dividing the sum for each seal type by the nominal diameter of the tank. Then compare these total gap areas per unit of tank diameter for the primary seal and secondary seal to the respective standards for the seal type in par. (a) 2.

e. In the event that the seal gap measurements do not conform to the specifications in par. (a) 2., repair the defect according to sub. (11).

f. Maintain a record of the inspection according to s. NR 665.1090(2).

2. Visually inspect the external floating roof according to all of the following requirements:

a. Visually inspect the floating roof and its closure devices to check for defects that could result in air pollutant emissions. Defects include, but are not limited to, holes, tears or other openings in the rim seal or seal fabric of the floating roof, a rim seal detached from the floating roof, all or a portion of the floating roof deck being submerged below the surface of the liquid in the tank, broken, cracked or otherwise damaged seals or gaskets on closure devices and broken or missing hatches, access covers, caps or other closure devices.

b. Perform an initial inspection of the external floating roof and its closure devices on or before the date that the tank becomes subject to this section. Thereafter, perform the inspections at least once every year except for the special conditions provided for in sub. (12).

c. In the event that a defect is detected, repair the defect according to sub. (11).

d. Maintain a record of the inspection according to s. NR 665.1090(2).

3. Prior to each inspection required by subd. 1. or 2., notify the department in advance of each inspection to provide the department with the opportunity to have an observer present during the inspection. Notify the department of the date and location of the inspection as follows:

a. Prior to each inspection to measure external floating roof seal gaps as required under subd. 1., prepare and send written notification so that the department receives it at least 30 calendar days before the date the measurements are scheduled to be performed.

b. Prior to each visual inspection of an external floating roof in a tank that has been emptied and degassed, prepare and send written notification so that the department receives it at least 30 calendar days before refilling the tank except when an inspection is not planned as provided for in subd. 3. c.

c. When a visual inspection is not planned and the owner or operator could not have known about the inspection 30 calendar days before refilling the tank, 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 the department receives it at least 7 calendar days before refilling the tank.

(d) Safety devices, as defined in s. NR 665.1081, may be installed and operated as necessary on any tank complying with this subsection.

(7) The owner or operator who controls air pollutant emissions from a tank by venting the tank to a control device shall meet all of the following requirements:

(a) Cover the tank with a fixed roof and vent the tank directly through a closed-vent system to a control device according to all of the following requirements:

1. Design the fixed roof and its closure devices to form a continuous barrier over the entire surface area of the liquid in the tank.

2. Equip each opening in the fixed roof not vented to the control device with a closure device. If the pressure in the vapor headspace underneath the fixed roof is less than atmospheric pressure when the control device is operating, design the closure devices 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 cover opening and the closure device. If the pressure in the vapor headspace underneath the fixed roof is equal to or greater than atmospheric pressure when the control device is operating, design the closure device to operate with no detectable organic emissions.

3. Make the fixed roof and its closure devices of suitable materials that will minimize exposure of the hazardous waste 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 consider 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 liquid and its vapor 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.

4. Design and operate the closed-vent system and control device according to s. NR 665.1088.

(b) Whenever a hazardous waste is in the tank, install the fixed roof with each closure device secured in the closed position and the vapor headspace underneath the fixed roof vented to the control device except as follows:

1. Venting to the control device is not required, and opening of closure devices or removal of the fixed roof is allowed at the following times:

a. To provide access to the tank for performing routine inspection, maintenance or other activities needed for normal operations. Examples of those activities include those times when a worker needs to open a port to sample liquid in the tank or when a worker needs to open a hatch to maintain or repair equipment. After completing the activity, promptly secure the closure device in the closed position or reinstall the cover, as applicable, to the tank.

b. To remove accumulated sludge or other residues from the bottom of the tank.

2. Opening of a safety device, as defined in s. NR 665.1081, is allowed at any time conditions require doing so to avoid an unsafe condition.

(c) Inspect and monitor the air emission control equipment according to all of the following procedures:

1. Visually inspect the fixed roof and its closure devices to check for defects that could result in air pollutant emissions. Defects include, but are not limited to, 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.

2. Inspect and monitor the closed-vent system and control device according to the procedures in s. NR 665.1088.

3. Perform an initial inspection of the air emission control equipment on or before the date that the tank becomes subject to this section. Thereafter, perform the inspections at least once every year except for the special conditions provided for in sub. (12).

4. In the event that a defect is detected, repair the defect according to sub. (11).

5. Maintain a record of the inspection according to s. NR 665.1090(2).

(8) The owner or operator who controls air pollutant emissions by using a pressure tank shall meet all of the following requirements.

(a) Design the tank to not vent to the atmosphere as a result of compression of the vapor headspace in the tank during filling of the tank to its design capacity.

(b) Equip all tank openings with closure devices designed to operate with no detectable organic emissions determined using the procedure in s. NR 665.1084(4).

(c) Whenever hazardous waste is in the tank, operate the tank as a closed system that does not vent to the atmosphere except under any of the following conditions:

1. At those times when opening of a safety device, as defined in s. NR 665.1081, is required to avoid an unsafe condition.

2. At those times when purging of inerts from the tank is required and the purge stream is routed to a closed-vent system and control device designed and operated according to s. NR 665.1088.

(9) The owner or operator who controls air pollutant emissions by using an enclosure vented through a closed-vent system to an enclosed combustion control device shall meet all of the following requirements:

(a) Locate the tank inside an enclosure. Design and operate the enclosure according to the criteria for a permanent total enclosure in Method 204-"Criteria for and Verification of a Permanent or Temporary Total Enclosure" of appendix M of 40 CFR part 51, incorporated by reference in s. NR 660.11. The enclosure may have permanent or temporary openings to allow worker access; passage of material into or out of the enclosure by conveyor, vehicles or other mechanical means; entry of permanent mechanical or electrical equipment or direct airflow into the enclosure. Perform the verification procedure for the enclosure in Section 8 of Method 204 initially when the enclosure is first installed and, thereafter, annually.

(b) Vent the enclosure through a closed-vent system to an enclosed combustion control device that is designed and operated according to the standards for a vapor incinerator, boiler or process heater in s. NR 665.1088.

(c) Safety devices, as defined in s. NR 665.1081, may be installed and operated as necessary on any enclosure, closed-vent system or control device used to comply with pars. (a) and (b).

(d) Inspect and monitor the closed-vent system and control device as specified in s. NR 665.1088.

(10) The owner or operator shall transfer hazardous waste to a tank subject to this section according to all of the following requirements:

(a) Except as provided in par. (b), transfer hazardous waste to the tank from another tank subject to this section or from a surface impoundment subject to s. NR 665.1086 using continuous hard-piping or another closed system that does not allow exposure of the hazardous waste to the atmosphere. For the purpose of complying with this paragraph, an individual drain system is a closed system when it meets 40 CFR part 63, subpart RR-National Emission Standards for Individual Drain Systems.

(b) Paragraph (a) does not apply when transferring a hazardous waste to the tank under any of the following conditions:

1. The hazardous waste meets the average VO concentration conditions in s. NR 665.1083(3) (a) at the point of waste origination.

2. The hazardous waste has been treated by an organic destruction or removal process to meet s. NR 665.1083(3) (b).

3. The hazardous waste meets s. NR 665.1083(3) (d).

(11) The owner or operator shall repair each defect detected during an inspection performed according to sub. (3) (d), (5) (c), (6) (c) or (7) (c) as follows:

(a) Make first efforts at repair of the defect no later than 5 calendar days after detection, and complete the repair as soon as possible but no later than 45 calendar days after detection except as provided in par. (b).

(b) Repair of a defect may be delayed beyond 45 calendar days if the owner or operator determines that repair of the defect requires emptying or temporary removal from service of the tank and no alternative tank capacity is available at the site to accept the hazardous waste normally managed in the tank. In this case, repair the defect the next time the process or unit that is generating the hazardous waste managed in the tank stops operation. Complete repair of the defect before the process or unit resumes operation.

(12) Following the initial inspection and monitoring of the cover as required by the applicable provisions of this subchapter, subsequent inspection and monitoring may be performed at intervals longer than one year under the following special conditions:

(a) In the case when inspecting or monitoring the cover would expose a worker to dangerous, hazardous or other unsafe conditions, the owner or operator may designate a cover as an "unsafe to inspect and monitor cover" and comply with all of the following requirements:

1. Prepare a written explanation for the cover stating the reasons why the cover is unsafe to visually inspect or to monitor, if required.

2. Develop and implement a written plan and schedule to inspect and monitor the cover, using the procedures specified in the applicable section of this subchapter, as frequently as practicable during those times when a worker can safely access the cover.

(b) In the case when a tank is buried partially or entirely underground, inspect and monitor, as required by the applicable provisions of this section, only those portions of the tank cover and those connections to the tank (e.g., fill ports, access hatches, gauge wells, etc.) that are located on or above the ground surface.