Abstract: A transportable elongated tank for contaning fluids which includes a pair of opposed side walls, a front wall, a back wall and a floor assembly. The floor assembly includes a plurality of longitudinal spaced beams which are interconnected by a plurality of longitudinally spaced, substantially parallel, transversely extending, trapezoidally shaped channel plates. Multiple arrays of the channel plates are provided, with each array including a pair of end-lapped, reversely turned channel plates disposed centrally with respect to the longitudinal centerline of the tank, and such pair of channel plates having relatively smaller end portions overlapped and secured to each other. The several channel plates each have a first edge flange located in a common plane containing all such first edge flanges, and a second edge flange. The second edge flanges of the several channel plates are located in, and define, two planes extending at an angle to each other and converging at the centerline of the tank.