The segmented cover is made of juxtaposed cover segments mounted over a wastewater reservoir. Floating beams define each of these cover segments, and a floating membrane is removably mounted to the floating beams over each of the cover segments. The floating beams are enclosed in a common sealed tubular envelope, which is connected to gas-impermeable connections joining the floating beams to a wall-covering skirt and to the perimeter walls of the reservoir. Because of the sealed continuous tubular envelope enclosing the floating beams, the wall-covering skirt and the gas-impermeable connections, each segment of the cover is independently sealed from outside environment and from an adjoining segment. Biogas collection from the wastewater reservoir can be maintained even when one segment of the cover is open.