When the city of Chattanooga, Tennessee decided to capture and reuse its stormwater to irrigate municipal gardens, urban planners envisioned a water tower that would serve as a monument to this contribution to sustainability.
Aesthetics were a key factor in the design because the water tower was to be located in the middle of a recently revitalized downtown. Under these circumstances, 304 stainless steel won out over more conventional materials - such as lined carbon steel or reinforced concrete - as the building material of choice.
Aerial View of Downtown Chattanooga, Tennessee
“This tank is in a growing section of town and it had the potential to be an eyesore and an unwanted fixture in that area,” says Tom Schull, marketing manager for Chattanooga Boiler and Tank Co., the company that built the tank. “The designers were able to overcome that. It doesn’t look like a water tank; it looks like a work of art.”
But eye appeal was not the only reason Consolidated Technologies Inc., the engineering contactor on the water tower project, proposed stainless steel. Carbon steel tanks are much more susceptible to the corrosion caused by fluctuating water levels and, as a result, incur higher maintenance costs.
“When (the city) compared the painting, lining and maintenance issues over the lifetime of the product, that became a factor in the choice of bid,” says Schull.
The stainless steel option was doubly cost-effective because the builders were able to assemble the tank at their nearby factory and avoid the expense and hassle of painting a carbon steel tower in the middle of a busy downtown core. In fact, Chattanooga Boiler came in as the lowest bid on the project, at US$159,947, with their stainless steel tank proposal, according to city records.
In recognition of all these factors, the Steel Plate Fabricators Association awarded the Chattanooga public works department the “Steel Tank of the Year” award in 2002 for devising a practical alternative to stormwater retention.
The 75-ft.-tall 16-ft-diameter tank is part of a larger under-and-above ground water storage system that can store up to 865,000 gallons of water within concrete pipes, box culverts and within the tank itself, which has a capacity of 105,000 gallons.
Two submersible pumps force water from the underground storage through sand filters to remove solids before the water enters the aboveground tank. The filtered gray water is then used to irrigate the streetscape, flush and drain stormwater catch basins and water trees and shrubs in the downtown area.
The unique water tower sits in the middle of a 70-acre landscaped plaza that is bounded on all sides by city streets. In another nod to curb appeal, the tower flares out at the top to a diameter of 26 ft.
“We’re not architects, but we’re pretty proud of (the tank),” says Allen Stephens, senior vice-president of Consolidated Technologies Inc., who managed the project on behalf of the city of Chattanooga. “We were able to take something utilitarian and turn it into something that is aesthetically pleasing.”