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TO: Mayor Robert J. O'Connor
FROM: Jason Bauer, P.E. Engineering Construction Coordinator
DATE: January 13, 2017
SUBJECT:
Resolution to authorize a Professional Services Agreement to assist with water main flushing for the City-Wide Water Main Distribution System Flushing Program.
PURPOSE:
To obtain City Council approval to execute a professional engineering services agreement with Crawford, Murphy & Tilly, Inc., Aurora, IL (CMT) to assist with water main flushing for Area 1, as shown on Exhibit B of the attached agreement.
BACKGROUND:
The City of Aurora's water main distribution system is a large, robust, web of interlinked piping ranging in size from 4-inch to 20-inch diameters with a total length of more than 740 miles. This system provides potable water in adequate quantities and pressures for commercial, industrial, residential, and fire-fighting uses. As with all complicated systems, regular maintenance and repairs are required to keep the system working acceptably and efficiently. One type of standard maintenance activity for sustaining the performance of the water distribution system is a system-wide water main flushing program.
Because water mains are sized to handle required firefighting flows, which may be several times larger than domestic and commercial water use needs, the velocity of flow through the pipes is normally fairly low. Due to this, solids may settle on the bottom of pipes. Over time, these deposits reduce the "carrying capacity" of the pipe, and they can also be a source of color, taste, and odor if the deposits are stirred up by short-term increases in flow (i.e. Aurora Fire Department hydrant flow testing, water main breaks, etc.).
DISCUSSION:
Historically, the City of Aurora only performed reactionary spot-flushing in areas where water quality complaints were received. A system-wide, planned, organized program, instead of reactionary spot-flushes, will selectively open and close hydrants and valves to a precise s...
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