Engineers: More tests needed to determine fixes for Naperville bell tower
Before Naperville officials can decide what to do about structural issues with the city's 17-year-old bell tower, they must do more research.
That was the message from several engineering experts who attended or phoned in to a meeting Wednesday to share potential fixes for Moser Tower, the 160-foot-tall spire that holds the Millennium Carillon.
"You have some more work to do before you could even come to someone like us to ask how much would this cost," said Tom Chakos with Golf Construction, a Chicago-based restoration company.
Leaders of the Riverwalk commission, which oversees the tower, took the engineers on a tour so they could understand the deficiencies discovered in a consultant's report -- mainly cracked concrete, corrosion of structural steel, deteriorating mortar and sealant, and water leakage into the lower-level electrical room.
"Those are the primary issues that need to be addressed if a long life is going to be breathed into this structure," said John Frauenhoffer of Engineering Resource Associates in Warrenville, which conducted the $50,000 study for the Riverwalk commission.
How to address these structural problems -- and whether to bother fixing them at all -- already has become a challenging question since the city released the report in May.
Riverwalk commission Chairman Geoff Roehll told the engineers some residents want to keep the tower and fix its flaws, calling it iconic, while others never supported its construction cost that grew to $7.1 million and don't want to see it eat up any more tax dollars.
With opposition and support for preserving the tower both building, Roehll said the commission invited in outside engineers to forecast the cost and method of repairs, how long the repaired tower could last and how much it would cost to maintain.
The report by Engineering Resource Associates estimated full fixes and maintenance -- including enclosing the lower 72 feet of the tower to match initial designs -- could cost as much as $3.75 million. But the city wants to consider other options.
Engineers including Tim Verdin, of Verdin Bells & Clocks in Cincinnati, said they observed "evidence of inferior precast (concrete) and inferior craftsmanship," so they warned more cracks will continue to occur over time.
Many other issues involve a lack of waterproofing in the areas intended to be protected by glass, and they could be fixed in a "surgical" manner that will put the tower on a course toward stability, said Barnaby Wauters, with Brush Architects in Chicago and Echem Consultants in New York state.
But the structure might need "heavy maintenance" to begin with to catch up from years of "not doing much," said Andrew Coffey, with Advanced Structural Engineering in Phoenix.
The tower was built in 2000 by the now-defunct Millennium Carillon Foundation and completed in 2007 with the city of Naperville as its owner, said Jan Erickson, Riverwalk administrator. With two owners and two phases of work, its development also included two architects, two engineers and two primary construction firms.
The disconnect between development phases has made it difficult for the city to locate all the records related to construction techniques and materials, such as "shop drawings" the touring engineers asked for repeatedly during their visit.
Having the drawings as well as more information about the strength or deterioration of the tower's four tall pillars and seven tubular support rings could help engineers determine work plans and cost estimates.
Frauenhoffer said his consulting firm knows exactly what tests need to be done, but the testing itself can be costly. It likely will require much advanced planning and the use of scaffolding to access the upper reaches of the pillars.
The city plans to study options to fix the tower for the next several months under the guidance of a task force Mayor Steve Chirico is appointing.