Abstract: A cover system for covering an entrance of an underground structure. The cover system comprises a frame structure attached to a foundation of the entrance; and a seal gasket configured to provide a seal between the frame structure and the foundation and between the frame structure and a panel of the cover system. The panel further includes a plurality of engagement members that engage the panel with the frame structure.

Abstract: A cover system for covering an opening, e.g., to an underground facility, watertight, includes one or more waterproof panels and a seal gasket for each panel, or a seal gasket common to a plurality of panels, configured to extend peripherally relative to the panel(s) and the opening, and adapted to be positioned between the panel(s) and the periphery of the opening, and one or more clamping devices for each panel which engage the respective panel and the periphery of the opening and/or structure extending over and attached to the opening to clamp the respective panel over the opening and compress the respective seal gasket.