A new aluminum, clear-span roof was installed over the Columbian Park water reservoir in Lafayette, Ind., to protect the water from vandalism and park animals, and to prevent the sunlight from breaking down the chlorine needed to keep the water algae-free.
Until recently, the reservoir had been protected by a floating cover made of a polyethylene fabric that had to be replaced approximately every 15 years. The cover also had to be cleaned on a regular basis.
When it was time to replace the last cover, management considered other options. The bid process began with a list of requirements: the new cover had to be clear-span, low maintenance, and resistant to corrosion.
One of the most important requirements was that the new cover be made from either aluminum or stainless steel, said Charles Barker of Hawkins Environmental, the engineering firm for the project. The chlorine used to treat the water is corrosive to almost every other building material.
Temcor proposed an all-aluminum truss-vault roof system to cover the 42,423-square-foot reservoir, which is 179 feet by 237 feet. The clear-span roof would be resistant to moisture and corrosion, and require minimal maintenance for many years. Also, Temcor engineered a unique erection system that allowed the roof to be installed without taking the reservoir out of service.
The installation system consisted of a u-channel track constructed along the sides of the reservoir, bolted to the sides of the grade beam foundation and extending past the end of the reservoir, ending at a construction staging area.
The first of 11 trusses was built in place over the track in the staging area. The truss, built with wheels fitted into the u-channel, was then pushed back 20 feet away from the staging area and over the reservoir. Once the first truss was supported into its upright position with a slide assembly, the second truss was completed, rolled along the tracks, attached to the first truss and the two trusses were pushed back another 20 feet. This process was repeated until all 11 trusses were in place over the reservoir.
The system was designed and engineered so that the seven-ton trusses could be pulled into place by just two men with a cable come-along, said Bill Baxendell, Temcors director of construction.
Once all of the truss sections were completed, the entire roof frame was jacked up so that the wheels could be removed. The roof frame was then lowered back down and bolted to the walls of the reservoir and the aluminum panels were installed.
The entire roof system was completed in 10 weeks, with an average daily crew size of seven people.
The roof looks great and has been very well received by the locals, Barker said. The reservoir is in a very public area of the city and aesthetics were important.
