Cracks are appearing in many places in the concrete slab that forms the floor of the main lobby of the Robert Crown Center, 1801 Main St. Concrete contracts as it cures, and often shrinkage cracks appear afterward.
A memo from the city’s Capital Planning and Engineering Bureau Chief Lara Biggs said the project’s architect, Chicago-based Woodhouse Tinucci Architects, and its construction manager, Bulley & Andrews, have told city staff they believe the cracking is expected for this type of floor and within acceptable limits.
But a majority of City Council members apparently felt it was worth $12,800 of the taxpayers’ money to pursue an investigation into the cause of the cracking, since the building has been open only since 2020.
By a 7-2 vote at the Sept. 27 meeting, council members approved a $12,800 contract with Wiss, Janney, Elstner Associates of Northbrook to investigate the sources and causes of the cracks.
The original proposal from Wiss, Janney was for $46,000 and included two phases. At the Administration and Public Works Committee meeting, held earlier in the evening, committee members agreed to fund only the first phase of the contract and amended the amount to $12,800.
During discussion at the council meeting, Council member Bobby Burns (5th Ward) said at first he did not support the investigation, among other reasons because he felt the measure was another aspect of the ongoing opposition to and concern about the cost of the new community center.
After talking with a local businessman in the concrete business, though, he said he became convinced that this was a serious matter – not just because of the width of the cracks but how quickly they appeared.
The nays and the phases
Council members Melissa Wynne (3rd Ward) and Jonathan Nieuwsma (4th Ward) voted against the proposal. Wynne did not give a reason for her vote. Nieuwsma said he had “no reason to second-guess the experts that have been involved with the project, “but $12,800 to put this behind us may be the price we will have to pay.”
The city requested a proposal only from Wiss, Janney, according to Biggs’ memo, “as they are known to be expert in the field of concrete failure investigation.”
In a letter to Stefanie Levine, Senior Project Manager for the city, Flora Calabrese and Michael Fornek of Wiss, Janney outlined the two phases of the proposal, including the scope of work and costs entailed.
Referring to a meeting at Robert Crown on Aug. 16, the letter noted “concerns were raised regarding cracking that has occurred in the floor slab. The objectives of our investigation would be to identify the probable causes of the cracking, the potential for the cracking to worsen, and possible repairs that can be made to avoid raveling or other further distress at the cracks.”
The scope of the first phase is to look at documents pertaining to the construction of the slab, such a soil-boring logs, geotechnical reports, structural design drawing.
A field survey will entail mapping the cracks at the surface and surveying the top reinforcing bars. The final aspect of phase 1 will be a written report describing the firm’s observations and findings from their reviews and analyses, along with opinions regarding the likely causes of the cracking, options for repair and, if needed, further investigations.
Phase 2, which the council did not approve, would focus on construction materials and include an analysis of the cracks and their age, possible factors impacting the movement of the slab during construction, soil borings to determine the suitability of the fill, compaction and settlement.
Depending on Wiss, Janney’s findings during phase 1, City Council will decide the next steps.