DOUBLE WALL STORAGE TANK |plastic tanks|polyethylene tank|secondary containment|diverse plastic tank The ACO double wall storage tank addresses all environmental and safety concerns and feature self-supporting, space saving designs. The Open-Top Outer Containment configuration for the double wall storage tank is also available. ACO’s molding process provides uniform sidewalls and domes that eliminates the problem of domes collapsing. Our Double-Wall storage tank is designed with wall thicknesses equal to or greater than that required by ASTM D-1998 standards. By calculating the wall thickness at the bottom of each tank where hoop stress is greatest, we then produce uniform thickness throughout the entire wall. This allows for a more uniform cure with less stress, resulting in greater strength in the top portion of the tank, an area of vital importance when securing seismic or wind-load restraint systems. The double wall storage tank provides an optimal protection against hazardous chemical spills into the environment. Inner tank dome overlaps outer tank sidewall to prevent rainwater, snow and debris from entering into the co