R2004-71 APPROVING CONTRACT AMENDMENT

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_ , _ COUNCIL COMMUNICATION FORM Engineering & Infrastructure Memorandum NO. 2004-37 Apri126, 2004 TO: Honorable Mayor Osborne and City Council FROM: Steve Garm , ity Manager � Stephen Sw s n, P.E., Director of Engineering& Infrastructur�P� Matthew C. Ne ell, P.E., City Engineer� SUBJECT: Renovation of Parking Garage B, City Project 2003-12 SUMMARY RECOMMENDATION: Staff recommends that the City Council approve the attached resolution approving a funding increase for the Renovation of Parking Garage B, City Project 2003-12. The resolution authorizes the City Manager and the Director of Engineering & Infrastructure to increase the existing $465,668 contract amount by$134,332 to a maximum expenditure of up to $600,000 to fully complete the structural repairs to City Parking Garage B located on the northwest corner of Water/North Streets. BACKGROUND: On March 1, 2004, the City Council awarded a contract for $465,668 with Golf Construction, Inc., to perform reconstruction work on City Parking Garage B. Work on the parking garage has commenced. Concrete removal around the deteriorated portions of the parking deck and the locations of new removal areas are rapidly exceeding the quantities estimated in the original design of the restoration work. During the design process, the full scope of deck removal is very difficult to accurately estimate. These quantities are typically estimated by dragging a chain or otherwise sounding the concrete surface to determine if the concrete has weakened or separated from the main structure. This occurs when water gets into the deck and corrodes the reinforcing steel. The rusting steel expands, forcing the concrete around it to break free of the deck. It is hard to determme accurate quanhties of full depth repairs vs. partial depth repairs smce rt is hard to determine how deep the weakened concrete extends. The parking garage deck is only 4 inches thick which leaves little room for error in deciding between a partial and a full deck repair. The in depth structure review being conducted as part of the reconstruction project has determined that full depth repairs will approach 2,200 square feet in comparison with the original estimate of 400 square feet.