TECHNOLOGY FOCUS - POLYMERS - Preferred Method: The designing step (a) is designed to fit within a secondary containment system for an above ground storage tank, or designed to fit underneath a tank battery. The step (b) is performed until the substrate coating is at least 50 mils thick. The method further involves (c) aligning the coated substrate with a tank battery; and (d) positioning an above-ground storage tank over the at least one coated substrate where at least one coated substrate forms the tank base. The method further involves (c) aligning the at least one coated substrate adjacent to a second coated substrate, where the second coated substrate is made by the same method as at least one coated substrate such that at least one seam is formed in between the two coated substrates and an outer periphery is formed around the edges of the aligned two coated substrates. The method further involves (d) securing each of the two coated substrates together around the outer periphery to form the tank base. The method further involves (e) positioning an above-ground storage tank over the tank base. The securing step (d) further involves using a strap around the outer periphery of the two coated substrates. The coating step (b) is performed using a spray device that operates at 165 degrees F and a pressure of 1800 pounds per square inch. The method further involves (d) aligning a third coated substrate, the third coated substrate made by the same method as at least one coated substrate, with the at least one coated substrate and the second coated substrate such that at least two seams are formed in between the three coated substrates and an outer periphery is formed around the edges of the aligned three coated substrates. The method further involves step of (e) securing each of the three coated substrates together to form the tank base. The method further coated substrates, made by the same method as at least one coated substrate, are aligned adjacent to and secured to one another to form the tank base. Preferred Components: The designing step (a) utilizes a substrate made of expanded polystyrene. The step (b) is performed with a polyurea elastomer. The elastomer is comprised of polyurea. The substrate is comprised of polystyrene. The substrate has a foam density of 2 pounds per cubic foot of foam weight. The tank base has a height of 3-12 inches. The elastomer coating is at least 50 mils thick. EXAMPLE - No suitable example is given.