R2019-89 Resolution Authorizing a Professional Services Agreement with Hanson Professional Services Inc. for Lake Decatur Dam Gates Evaluation

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PUBLIC WORKS MEMORANDUM NO. 2019-48 DATE: May 21,2019 TO: Honorable Mayor Julie Moore Wolfe and City Council Members � FROM: Scot Wrighton, City Manager Matthew Newell,P.E., Director of Public Works Keith Alexander,Water Production Manager � SUBJECT: Resolution Authorizing a Professional Services Agreement with Hanson Professional Services Inc. for Lake Decatur Dam Gates Evaluation � SUMMARY RECOMMENDATION: Council adopt the attached Resolution authorizing a Professional Services Agreement with Hanson Professional Services Inc. for Lake Decatur Dam Gates Evaluation for a fee not to exceed $153,900. PAST COUNCIL ACTION: None on this subject. BACKGROUND: On Monday, December 10, 2018, while operating the Lake Decatur dam bascule gates, the north bascule gate failed to raise from its full down position. The bascule gates are the long gates that � span the top of the dam. Large hydraulic pistons lower or raise the gates as needed to allow water to flow over the dam to maintain the necessary lake depth. This failure created a 24-hour , period during which a considerable amount of water flowed uncontrolled out of the lake. The lake lost nearly 2' of water overnight. On Tuesday, December 11,the gate finally responded to repeated activation attempts and was raised to its full up position. Since then, we have not lowered the north gate below its 60%up position. � It is believed that one of the four hydraulic pistons that power the north bascule gate seized for some reason. However, there could also be other explanations, including debris blocking the front of the gate which sits underwater out of sight for normal inspection. With the summer weather approaching and hopefully reduced Sangamon River water flow,the Public Works Department proposes to retain the services of Hansen Professional Services to review the bascule gates including the hydraulic cylinders to determine the cause of the December failure and recommend the necessary repairs.