Technical Engineering and Design Guides, as adapted from the U.S. Army Corps of Engineers, No. 21 This guide provides a framework for the structural design of closure structures for openings in levees and floodwalls of inland local flood protection projects. Topics include: design requirements for aluminum and steel stoplog closure structures; design requirements for steel swing, miter, trolley, and rolle gate closure structures; design and selection of closure types, focusing on structural analyses, appurtenant components, and corrosion protection; design provisions for operational, functional, maintenance, aesthetics, safety, security, construction, and economic considerations; design process and coordination; facilities requiring closures; closure structure types; stress, loading, and design analysis criteria; gate operating equipment; seal assemblies; embedded metals; and corrosion protection criteria.