When Chicago’s beloved former First Lady, Maggie Daley, lost her battle to breast cancer back in 2011, Mayor Rahm Emanuel was already in the process of talking to Daley’s family about a way to permanently honor her. In August 2012, he announced that a nearly 20-acre parcel in the northeast corner of Grant Park would be redesigned by Michael Van Valkenburgh Associates and renamed Maggie Daley Park, creating a $60 million project that would breathe new life into downtown.

Ten years prior, American Hydrotech, a Chicago-based company that develops and distributes premium waterproofing and roofing products, had been hired to waterproof the parking garage beneath Millennium Park, the park adjacent to Maggie Daley Park, just across Columbus Drive. When the company was asked to handle the new park, Bill Schaefer, the north-central district manager at American Hydrotech, says the company was thrilled. “It’s an honor to have been a part of two iconic projects that define downtown Chicago,” Schaefer says.

MDP Climbing Wall

The park, designed by Michael Van Valkenburgh Associates and filled with active amenities such as rock-climbing walls and ice-skating “ribbons,” is actually built on top of a downtown parking garage. Rendering: Michael Van Valkenburgh Associates

Re-waterproofing the parking garage beneath Maggie Daley Park seemed simple enough—American Hydrotech has been doing this for almost 40 years—except for one small thing: this project would be one of the biggest projects in the history of the company. At 750,000 square feet, the site in question is equivalent to 12 football fields.

The parking structure had been waterproofed in the 1970s, but over the years, the concrete had been compromised.Typically, American Hydrotech looks to use a site’s natural slope to assist with drainage, and while the Maggie Daley Park parking garage slopes from north to south, an existing bridge built 10 years ago made drainage difficult. “Basically, there was a small lake forming,” Schaefer says. “We resolved it by diverting water away from, and then off of the site.”

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The 20-acre park is using Hydrotech’s waterproofing membrane to ensure a watertight roof for the parking garage below.

To ensure the project’s integrity, American Hydrotech joined forces with Western Waterproofing Company, which served as general contractor on this phase of the project and which Schaefer says did an excellent job. “Not only did they do a terrific job installing the Hydrotech waterproofing, but they also self-performed all of the surface prep, concrete repair, and some new concrete work,” he says. International Leak Detection, another trusted partner, used what’s known as Electric Field Vector Mapping (EFVM) to find and document any possible leaks in the roofing membrance.

“We’ve never taken on a job of this size in Chicago,” Schaefer says. “It was maybe a little challenging at first, but this is quality that will last. There’s a lot of talk about sustainability these days, and the best way for us to be sustainable was to ensure that the City of Chicago wouldn’t have to pull everything up and waterproof the structure all over again. In 40 years, this structure will still be waterproof. That makes us proud.”