R96-114 AUTHORIZING THE EXECUTION OF A CHANGE ORDER

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, ' r• , � � BLACK & VEATCH 8400 Ward Parkway,P.O.Box No.8405,Kansas C�ry,Misso�n 64114,(913)339-2000 Decatur, Illinois 6&V Project 11600.210 Waterworks Improvements B&V File B-1.1 Lake Decatur Dam . August 15, 1996 Bascule Gate Cylinder Inspection Mr. Bill Ratekin Assistant Engineer ' City of Decatur ' #1 Gary K. Anderson Plaza , Decatur, Illinois 62523 ; Dear Bill : The disassemble of bascule gate No. 8 cylinder again revealed a quanity of II, contaminated hydraulic oil and oily sludge trapped in the cylinder housing '� and no mechanical problems. From all observations,this material contains �, water and other grit�ty material and collects in the lower section of the � cylinder(below the piston) and in the upper section(on top of the piston) . '� Because this material is heaver that the normal hydraulic oil , it settles ' out in these dead zones and becomes trapped because the hydraulic piping connections are in the upper half of the cylinder. This contaminated I material should not be a problem until the quanity exceeds the volume of I the dead zone. When this occurs, this material is forced into the I hydraulic piping. Because this material contains a percentage of water, it � can freeze into an icy slush and may create a partial ice plug which would block or restrict flow from the cylinder. ; It is impossible to measure the volume of contaminated hydralic oil in the II cylinder. This situation make it difficult to speculate when the I contaminated hydraulic oil could become a problem in the hydraulic• piping. �I Considering the recent problems with operating the gates during the winter, I removing the contaminated hydraulic oil should eliminate this problem. Since the contaminated hydraulic oil cannot be removed without deactivating II the entire gate, now may be the time to consider this work since the south bascule gate is out of service. Although there is probably a way to extract I a portion of the contaminated oil without removing the cylinders, removal �, and disassembly of the cylinders allows the installation of drain plugs, ' complete removal of all comtaminated oil and sludge, cleaning of the cylinder walls to remove the oil build-up, and checking the piston rings. � Considering that Osage Constructor's Inc. has their equipment on-site and is experience with the removal , handling and disassembly of the cylinders. This would be an excellent opportunity to complete the work on the south bascule gate.