R2009-96 AUTHORIZING SECOND AMENDMENT TO AGREEMENT WITH HANSON PROFESSIONAL SERVICES, INC.

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6. Review Contractor submittals for conformance with the project specifications. 7. Review requests for payment by the Contractor for agreement with observed progress of the work. 8. Evaluate the condition of the downstream apron slab surface. This information will be used to prepare construction documents for the for the anticipated 2010 construction contract. 9. Conduct an Apron Slab Void Detection Survey using Ground Penetrating Radar(GPR)to deternvne the presence of voids under the downstream apron. 10. Conduct south embankment seepage monitoring. Continued seepage around the south side of the dam may warrant additional work in a future repair contract. 11. Provide record drawings detailing changes to the plans and specifications and provide electronic and hard copies for the City's records. Future Work The Lake Decatur Dam rehabilitation work is a three year, three phase project that is expected to approach a total cost of$4 million. The work will include the following: Phase 1, 2009 The Phase 1 dam rehabilitation project is to begin construction in July, 2009, with Council approval planned for July 6. This work will include: 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. The estimated construction cost is $1.4 million. Phase 2, 2010 The Phase 2 dam rehabilitation project is to be constructed summer of 2010. This work will include: 1. Evaluation of the 2009 test patch and patching the full downstream spillway. 2. Replace 4 hydraulic cylinders on the north bascule gate. The cylinders will be pre- purchased in the fall of 2009 to assure a summer 2010 delivery. 3. Grout crack injection of the dam to reduce water infiltration through the dam. The estimated total project cost is 1.4 million. Phase 3, 2011 '� The Phase 3 dam rehabilitation project is to be constructed summer of 2011. This work will include: 1. Repair of downstream scour damage below the dam. 2. Replace 4 hydraulic cylinders on the south bascule gate. The cyluiders will be pre- purchased in the fall of 2010 to assure a summer 2011 delivery. The estimated total project cost is 1.1 million. Several amendments to the Hanson Design Services Agreement will be recommended over the course of the 3 year dam rehabilitation work. While it may be possible to authorize engineering services for the fu113 years initially, experience has shown that it is better to approve amendments to the Agreement as the project progresses and more information is obtained. Page � 3