One way to open the door to new marketing opportunities is to find a new use for an existing product. Con/Span Bridge Systems, Dayton, Ohio, has done just that. Con/Span has found a new market for its modular bridge units--as underground storage vaults. The company combined 12 modular precast arch-box units with 2 modular end walls to create a concrete vault with inside dimensions of 96 feet long by 24 feet wide by 11 feet high. The vault contains eight storage tanks with a combined capacity of 54,000 gallons, and rests on a monolithic cast-in-place base slab 12 inches thick. The total cost of the project was $625,000. Because the vault uses precast segments originally designed for highway bridges, it is capable of carrying heavy traffic loads. In this case, a fill station where tank trucks empty their contents into the tanks is located directly above the vault.