New report estimates lower cost to repair Naperville bell tower
If Naperville officials decide to fix structural issues with the iconic Moser Tower, a new draft report spells out four ways they could do so, costing between $1.3 million and $2.4 million.
The updated prices in a draft report released Tuesday by Engineering Resource Associates are lower than estimates provided in a preliminary report on the structure's condition in April 2017.
Two years ago, consultants estimated it would cost between $1.6 million and $3.75 million to repair the tower so it can remain in place along the downtown Riverwalk, safely holding the Millennium Carillon and its 72 bells.
Since then, additional testing determined the spire is in better shape than feared, leaving it in "a proactive repair state where work and repairs can be designed to slow down or prevent additional issues," according to Tuesday's report.
The city could choose to repair problems with cracking concrete, corroded steel and a leaking plaza in one phase for $1.3 million; repair the same issues in three phases for $1.5 million; enclose the base of the tower to match original designs while repairing the concrete, steel and plaza in one phase for $2.2 million; or enclose the base and repair the same issues in three phases for $2.4 million.
Tearing down the 19-year-old tower built in 2000 and completed in 2007 would cost $660,000 if the structure is razed immediately or $1.6 million if it's done after also incurring maintenance costs for 30 years. Teardown costs remain unchanged from 2017 estimates.
But the report issued to a subgroup of the Riverwalk Commission called the planning, design and construction committee offers a new prioritization of repairs to help officials decide what to tackle first, said consultants Brian Dusak and Jacob Wolf with Engineering Resource Associates.
The report says the city first should fix concrete scaling and cracking for $512,000, aiming to complete the work within three years.
That's because concrete troubles -- caused partially by a high water-to-cement ratio found in samples from the structure -- are causing the biggest safety concern.
"Pieces of concrete potentially could fall off the tower at any time, frankly," Wolf said. Preventing that is "essentially priority No. 1."
The second priority should be to fix corrosion of structural steel for $585,000 within three to five years, the report says. Rehabilitating the plaza at the base of the tower is "not the most critical" and is the third-priority recommendation to be undertaken within five to seven years, Wolf said. Plaza fixes are estimated to cost $363,000.
Consultants say completing all the repairs will help stabilize the tower for the next 30 years. During that time, the city also would incur maintenance costs of $13,333 or $18,333 a year, with the lower cost predicted if the city encloses the lower 72 feet of the tower, as original designs spelled out.
Geoff Roehll, Riverwalk Commission chairman, asked whether the tower would be in better shape if officials pay the additional $710,000 it's estimated to cost for enclosure work alone.
Consultants effectively said no, as long as the concrete, steel and plaza repairs are finished and kept in good shape.
"I don't know that we're going to realize much additional benefit to enclosing the structure if we're making the repairs the way it stands now," Dusak said.
Members of the planning, design and construction committee heard a brief overview of the draft report Tuesday but did not indicate opinions about how repairs should be handled. Bill Novack, the city's director of transportation, engineering and development, said the committee aims to make a recommendation at its April 2 meeting for consideration first by the full Riverwalk Commission and then by the city council.