R2009-04 AUTHORIZING AGREEMENT HANSON PROFESSIONAL SERVICES, INC.

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from elevation 610 to 614.5. The following table summarizes the history of major construction projects for the Lake Decatur Dam: Year Activi 1922 Ori inal Construction 1950's Fish ladder removed 1954-55 Flashboards removed and bascule gate installed Sluice gate r lacement and trashracks installed 1955-1996 Sluice ates reconditioned 1955-1996 Resurfaced downstream face of s illway access latform 1995 Overlay placed on downstream face of s illway 1996 Shotcrete a lied to left and ri ht abutment walls 1998 North bascule gate hydraulic cylinders refurbished (Cylinders 1 thru 4) 2000 South bascule ate h draulic c linders refurbished (Cylinders 5 thru 8) 2000 Ap roximately 30 concrete anels on u stream slo e of right embankment r laced 2000 Pile cap and all concrete panels along the downstream right riverbank training wall r laced. 2001 New 'oints sawcut into s illwa overla to match ori inal dam 'oints 2001 Spalling along upstream face of outlet works and downstream face of spillway atched 2001 New ri ra laced downstream of stillin basin and alon the left river bank 2004 New sluice ate lift mechanism at the lower tailwater dam 2005 S allin alon u stream face of outlet works structure atched The Lake Decatur Dam is a Class 1 structure, as classified by the Illinois Department of Natural Resources. This classification indicates that failure of the dam would have a high probability of � causing loss of life or substantial economic loss. As a condition of the Operating Permit, the City is required to undertake an annual inspection. In October 2008, staffrequested a proposal from Hanson Professional Services to develop detail design drawings and prepare construction documents for a project to address the recommendations contained in the annual inspection reports for the past five years. On December 29, 2008, Hanson provided a Professional Services Agreement outlining the scope of work for the Lake Decatur Dam Repairs. The scope of work identifies four general groups of improvements needed: a. Repairs to the training wall between gated outlet works and spillway b. Repairs to north and south sections of the spillway c. Repairs to south abutment and training walls d. Repairs to the gated outlet structure. For a more detailed description of other improvements, please see the attached scope of work. Of particular note,one of the major scope items of the project consists in the concrete repair of the downstream face of the concrete spillway, a structure 476 feet in length and 20 feet in depth. Hanson recommends performing this repair over a two year period. During the 2009 construction year, the first year of this two year project, a 50 foot test panel would be undertaken. Over the following several months, the test panel will be inspected periodically to ascertain its performance. Page � 2