Jardine Water Purification Plant
PVC (Vinyl) Roof Caps Off Complex Reroofing of Engineering Marvel
ROOFING CHALLENGE: Built on rubble from the Great Chicago Fire of 1871 next to Navy Pier, the mammoth concrete vaulted James W. Jardine Water Purification Plant purifies one billion gallons of water funneled from Lake Michigan each day – more than any other purification system in the world – to be dispensed to five million customers. Fifty years of constant 80-degree relative humidity and chlorine processing inside the facility corroded the roof channels of the graveled coal tar pitch roof. A major demolition was in order along with the search for a roofing material that would take this engineering marvel into its next 50 years and beyond. The project would require complete containment areas, roof-load restrictions and unique stainless-steel expansion joints, among other complexities.
PVC (VINYL) SOLUTION
The installation was the largest, most complex reroofing project in Chicago in a decade. The project began with the erection of a 112,000-square-foot plywood scaffolding platform blanketed by a 60 mil membrane that established a leak-free zone over concrete filter beds below, allowing the facility to operate uninterrupted. Following the numerous intricacies of removing the coal tar roof and cellular glass insulation, 66 different types and sizes of precast concrete channels weighing between 225 and 500 pounds were hoisted by a specially modified crane, and all 30,000 had to be individually inspected and approved before installation. Seven miles of backer rod filled in seams between these slabs. Workers placed 712,000 board feet of two-inch cellular glass insulation over concrete roof channels, followed by 1,086 rolls of Flex FB Elvaloy® KEE/PVC 90 mil membrane installed in hot asphalt onto a built-up roofing assembly.
Spanning 448,000 square feet (the equivalent of 10.3 acres), the hot-air welded membrane today is “an integrated whole impervious to Chicago wind and weather extremes, chemicals, UV light and hundreds of birds congregating on the roof and leaving acidic deposits behind,” said John Doyle, president of Flex Membrane International Corp. in Leesport, Pennsylvania. “The new Jardine plant roofing system will perform reliably for many decades. We’ll come back in 50 years to see if it needs replacing.”