A sewer manhole cover includes a frame having an access aperture and a cover for covering the access aperture. A primary seal is generated when the cover is placed on the frame either by way of contact between the frame and cover or by way of a gasket received within a groove formed into one of the frame or cover, wherein the gasket is compressed between the frame and cover. A method is provided for generating a secondary seal between the frame and cover by applying an amount of a viscous compound to a circumferential surface of the frame or cover, wherein the secondary seal is formed when the cover compresses the compound when the cover is received within the frame.