Concrete work presented one of the biggest challenges for Pepper Construction Co. of Chicago when building the world's largest indoor saltwater pool for the Shedd Aquarium. Referred to as the Oceanarium, the project included 170,000 square feet of new building, three levels of steel and reinforced concrete construction. Principal walls were large curves. Some 90% of the trades involved had to work with materials they had not previously handled on a construction project. Museum quality was met with a huge communication effort.