Abstract: A composite above ground liquid storage vault. The vault includes an inner tank defining a containment cavity for the liquid. The inner tank is enclosed within an insulating layer and a monitor tube is positioned adjacent to the insulating layer so as to extend to a location exterior of the vault. A liquid impervious membrane encapsulates the monitor tube, the insulating layer and the inner tank. The encapsulated inner tank is positioned within an outer tank and spaced apart from the interior surfaces of the outer tank by spacers supporting the encapsulated inner tank. A structural and insulating material is located within this space so as to completely surround the inner tank and form a fire wall.