Abstract: Large capacity truck tankers periodically replenish the petroleum and other products in the underground storage tanks. These underground storage tanks corrode, and develop leaks releasing their petroleum products into the ground. As a result potable water supplies are contaminated, and the petroleum products remain in the ground for long periods of time. Fiberglass plastic tanks were developed to replace the metal tanks which corroded. If a sharp object such as a stone contacted the fiberglass tank, the recurring filling of the tank caused a slight degree of movement or working of the tank which in time resulted in the tank leaking. To overcome this problem, it has been determined that a containment vessel or barrier should surround the primary tank and that the space between the tank and the barrier should be inspected periodically to determine if leakage has occurred. If leakage occurs the tank and the barrier must be removed and replaced.

Abstract: An assembly line method of construction is applied to the making of the thin fiber reinforced shell that forms the external surface of the Fibrestone wall. An elongated endless movable belt has the desired recurring pattern to be applied as the external surface of the fiber reinforced shell. Spray guns movable transversely of the elongated belt are provided to spray concrete and chopped up reinforcing fibers on the belt to form a continuous Fibrestone panel strip as the belt moves past the spray guns. A plurality of elongated flex-ties mounted on suitable supports and each having one of their ends adapted to be secured to the upper surface of the fiber reinforced shell are dropped onto the spray formed shell while it is in the plastic or uncured state. To insure that the flex-ties are securely bonded additional concrete and chopped up fibers are sprayed on the flex-tie supports, and the area between the rows of flex-ties are rolled to provide a relatively smooth surface between the rows of flex-ties.