rectangular door 34 substantially mating access opening 29 is swingably connected along its upper outer edge to the upper outer edge of opening 29 by a piano hinge 36 a horizontal wire handle 37 is medially affixed to the outer face of door 34 proximate its bottom edge mounted on the lower border of the inside face of door 34 is a pair of laterally spaced male roll type separable coupling or catch member 38 a bag closure defining pair of rectangular panels or rigid flaps 39 is connected to the lower borders of the inside faces of side walls 24 above the level of the lower edge of opening 29 each of the panels 39 is of somewhat less than half the width of front or rear walls 26 and 27 and is connected along its upper outer edge to the inside face of respective side wall 24 by a piano hinge 40 a tubular resilient sealing gasket 41 of rubber or the like is suitably received to the free outside end face of each panel 39 and when the panels 39 are in their closed horizontal coplanar position the gaskets 41 are in a mutual compressed condition along their lengths mounted on the top face of each of the panels 39 along the end edge thereof proximate the upper border of opening 29 is a female expandable jaw type female separable coupling member 42 which complements coupling member 38 when panels 39 are in their lowered coplanar closed condition and door 34 is in its closed position engaging opening 29 coupling member 38 separably engage coupling member 42 to releasably lock panels 39 in their closed coplanar position moreover at least one of the panels 39.