Abstract: A method of forming a septic tank from a blow molded body having an interior and an exterior. The septic tank body is formed from one or more layers of plastic material that are chosen for their chemical, mechanical or other properties. The septic tank body includes a plurality of integral ribs to provide circumferential structurally rigidity and also includes compression molded flange portions to provide axial structural rigidity.

Abstract: A septic tank formed of a blow molded body having an interior and an exterior. The septic tank body is formed from one or more layers of plastic material that are chosen for their chemical, mechanical or other properties. The septic tank body includes a plurality of integral ribs to provide circumferential structurally rigidity and also includes compression molded flange portions to provide axial structural rigidity. Additionally, septic tank covers and riser systems are provided.

Abstract: A removable deck for an interstitial space between stories of a building has joist saddles adapted to be permanently secured to building truss members in the interstitial space, each saddle having a socket into which the end of a joist may be dropped. The joists are channel type members of a length equal to the space between trusses. Each joist has an upturned flange at its top and the deck members, of a chosen length to extend across selected number of joists, have slots across their bottoms for close engagement with the upturned flange of the joist. The joists have a strip of rubber-like material along their upper surfaces and the upturned flange has dimple-like projections spaced therealong for holding sidewise movement of the deck members to a minimum. Each deck member is of inverted channel shape, the upper surface of which is longitudinally slitted to provide good air circulation.