Covers referenced in water and wastewater treatment projects usually refer to Launder Covers which function as odor control hoods that entrap noxious gases generated in the wastewater treatment process. Launder Covers also prevent the growth of algae by elimination of sunlight; this reduces weir maintenance and enhances flow consistency. Covers are also used to cover other openings where access is needed but for safety and other reasons the opening needs to be covered when not being utilized. Covers are custom designed and can be used in both round and rectangular clarifiers, sludge thickeners, channels and other openings.