Abstract: Apparatus for draining a liquid which has been inadvertently freed from a primary storage container and captured in a containment space comprising a drain conduit extending from the containment space to a remote location, with said drain conduit having an opening in a lower part of the containment space into which captured liquid can flow by gravity when not closed; a valve, in the drain conduit, outside of the containment space; a pressurization line, containing a valve, communicating with the drain conduit between the drain conduit valve and the conduit opening; a closure in the drain conduit opening adapted to bar flow of captured liquid into the drain conduit; and a closure retainer releasably securing the closure in the drain conduit opening; whereby when it is desired to remove captured liquid from the containment space the pressurization line valve can be opened and fluid under pressure can be fed to the pressurization line to deliver it to the drain conduit with the drain conduit valve closed so that