R2011-131 APPROVING CONTRACT AMENDMENT

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Public Works Memorandum NO. 2011-57 DATE: August 8, 2011 TO: Honorable Mayor McElroy and City Council Members FROM: Ryan P. McCrady, City Manager Richard G. Marley, P.E., Director of Public Works Keith D. Alexander, Director of Water Management SUBJECT: Resolution Approving Contract Amendment Change Order No. 15, Global Infrastructure, Lake Decatur Dam Repairs, City Project 2009-02 SUMMARY RECOMMENDATION: It is recommended that the City Council approve the attached resolution authorizing additional funding, in the amount of$263,885.57,be added to the contract for the Lake Decatur Dam Repairs, City Project 2009-02, for a total project cost of$3,392,023.34. PRIOR COUNCIL ACTION: Appendix A provides a summary of prior Council actions. BACKGROUND: Summary of the Major Construction History of Lake Decatur Dam Appendix B provides a brief summary of past improvements to the Lake Decatur Dam. Lake Decatur Dam Repairs The Lake Decatur Dam Repairs project began in June, 2010. The project includes the following work: 1. Repairs to the upstream face of the dam. 2. Rehabilitation of the mechanical systems that raise and lower the sluice gates on the north side of the dam. 3. Replacing the seal systems for the bascule gates and sluice gates. 4. Removal of gate heaters along the bascule gates. 5. Installation of a concrete patch on the downstream spillway of the dam. 6. Replace all eight cylinders on the bascule gates of the dam. Currently, temporary bulkheads are installed on the lake side of the south bascule gate of the dam. These allow water to be drained from the bascule gate and provide opportunity for a thorough inspection of this portion of the dam. The bulkhead will remain in place while seals are replaced on the gates, some concrete repairs are made, and the hydraulic cylinders used to raise and lower the bascule gates are replaced. Page I 1