R96-114 AUTHORIZING THE EXECUTION OF A CHANGE ORDER

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.pF•�fC � 7 A a C I V 70 i � � %[LINO�Y August 27, 1996 PUBLIC WORKS MEMORANDUM NO. 96-58 II MEMORANDUM TO: Honora6le Ma or and Ci Council I� y h� �i FROM: William B. Sands, Interim City Manager � Bruce A. McNabb, Director of Public Works �r',�-2 Witliam A. Ratekin,Assistant City Engineer W SUBJECT: Lake Decatur Spiitway Rehabilitation Change Order City Project 891&E Enclosed for your approval at the September 3, 1996, City Council meeting is a resolution authorizing the Mayor to sign a change order for additional work on City Contract 8918-E, the Lake Decatur Spillway Rehabilitation Project. This work was discussed previously at the July 8, 1996, City Council Study Session. On December 15, 1995, while testing the operation of the south bascule gate, which had been repaired from previous damage, damage was once again inflicted on the gate. Since that time the City has removed two of the four hydraulic cylinders on the South bascule gate for thorough inspection. (The consulting Engineer's comments regarding this inspection are summarized in the attached letter.) The result of the inspection on the two cylinders showed the presence of a sludge buildup on the inside of the cylinder. There was sludge present in both the top and bottom half of the cylinder, though a larger volume was present in the bottom. The composition of the sludge consisted of inetal filings, new hydraulic oil, old hydraulic oil and water. It is now being speculated that with the presence of the water, when the gate was lowered in December 1995, some of the sludge and water was pushed out into the supply lines in the face of the spillway. The temperature on the day that the gate was moved was 45 degrees, though the previous six days had temperatures ranging from 30 degrees to near zero. This most likely caused the cylinder to stop functioning properly which caused the damage to the gate.