NR 664.1085(3)(a)4.4. Except as provided for in subd. 5., equip each opening in the floating membrane cover 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 cover opening and the closure device. NR 664.1085(3)(a)5.5. The floating membrane cover may be equipped with one or more emergency cover drains for removal of stormwater. Equip each emergency cover drain with a slotted membrane fabric cover that covers at least 90% of the area of the opening or a flexible fabric sleeve seal. NR 664.1085(3)(a)6.6. Make the 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 closure devices throughout their intended service life. Factors to consider when selecting the materials of construction and designing the cover and closure devices shall include organic vapor permeability, the effects of any contact with the liquid and its vapor managed in the surface impoundment, the effects of outdoor exposure to wind, moisture and sunlight and the operating practices used for the surface impoundment on which the floating membrane cover is installed. NR 664.1085(3)(b)(b) Whenever hazardous waste is in the surface impoundment, float the floating membrane cover on the liquid and secure each closure device in the closed position except as follows: NR 664.1085(3)(b)1.1. Opening of closure devices or removal of the cover is allowed at the following times: NR 664.1085(3)(b)1.a.a. To provide access to the surface impoundment 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 surface impoundment, or when a worker needs to open a hatch to maintain or repair equipment. After completing the activity, promptly replace the cover and secure the closure device in the closed position, as applicable. NR 664.1085(3)(b)1.b.b. To remove accumulated sludge or other residues from the bottom of the surface impoundment. NR 664.1085(3)(b)2.2. 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. NR 664.1085(3)(c)(c) Inspect the floating membrane cover according to all of the following procedures: NR 664.1085(3)(c)1.1. Visually inspect the floating membrane cover 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 cover section seams or between the interface of the cover edge and its foundation mountings; broken, cracked or otherwise damaged seals or gaskets on closure devices and broken or missing hatches, access covers, caps or other closure devices. NR 664.1085(3)(c)2.2. Perform an initial inspection of the floating membrane cover and its closure devices on or before the date that the surface impoundment becomes subject to this section. Thereafter, perform the inspections at least once every year except for the special conditions provided for in sub. (7). NR 664.1085(4)(4) The owner or operator who controls air pollutant emissions from a surface impoundment using a cover vented to a control device shall meet all of the following requirements: NR 664.1085(4)(a)(a) Cover the surface impoundment and directly vent it through a closed-vent system to a control device according to all of the following requirements: NR 664.1085(4)(a)1.1. Design the cover and its closure devices to form a continuous barrier over the entire surface area of the liquid in the surface impoundment. NR 664.1085(4)(a)2.2. Equip each opening in the cover not vented to the control device with a closure device. If the pressure in the vapor headspace underneath the cover 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 cover 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 using the procedure in s. NR 664.1083 (4). NR 664.1085(4)(a)3.3. Make the cover 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 cover and closure devices throughout their intended service life. Factors to consider when selecting the materials of construction and designing the cover and closure devices shall include organic vapor permeability, the effects of any contact with the liquid or its vapors managed in the surface impoundment, the effects of outdoor exposure to wind, moisture and sunlight and the operating practices used for the surface impoundment on which the cover is installed. NR 664.1085(4)(b)(b) Whenever hazardous waste is in the surface impoundment, install the cover with each closure device secured in the closed position and the vapor headspace underneath the cover vented to the control device except as follows: NR 664.1085(4)(b)1.1. Venting to the control device is not required, and opening of closure devices or removal of the cover is allowed at the following times: NR 664.1085(4)(b)1.a.a. To provide access to the surface impoundment 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 surface impoundment, 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 surface impoundment. NR 664.1085(4)(b)1.b.b. To remove accumulated sludge or other residues from the bottom of the surface impoundment. NR 664.1085(4)(b)2.2. 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. NR 664.1085(4)(c)(c) Inspect and monitor the air emission control equipment according to all of the following procedures: NR 664.1085(4)(c)1.1. Visually inspect the surface impoundment cover 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 cover section seams or between the interface of the cover edge and its foundation mountings, broken, cracked or otherwise damaged seals or gaskets on closure devices and broken or missing hatches, access covers, caps or other closure devices. NR 664.1085(4)(c)3.3. Perform an initial inspection of the air emission control equipment on or before the date that the surface impoundment becomes subject to this section. Thereafter, perform the inspections at least once every year except for the special conditions provided for in sub. (7).