The inner primary steel tank is assembled, welded and tested for tightness. The primary steel tank provides the underground structural performance for the Plasteel^® Double Wall Elutron^® Jacketed Tank. The aluminum foil stand-off material and outer fiberglass reinforced plastic (FRP) secondary containment jacket are applied 360° around the inner primary tank creating an interstitial space. The interstitial space between the primary tank and the secondary containment jacket is designed to provide access to detect a liquid in the interstitial space and containment of the liquid.