Agenda - Public Works Committee - 11/20/2012

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Public Works Committee 5. 1. Meeting Date: 11/20/2012 Submitted For: John Nelson By: Grant Riemer, Engineering /Public Works Title: Well # 4 Motor and Pump Repair Background: Construction for municipal well #4 began October 15th 1997 and was completed April 29th 1998. Well #4 produces 850 gallons a minute and has pumped a total of 1.6 billion gallons of water since coming on line in 1998. Well #4 was drilled to a depth of 325 feet and draws water from the Ironton Galesville Aquifer. In construction of the well, approximately 817 pounds of explosives were detonated at a depth of 290 to 320 feet to create the underground void needed to supply the pumping capacity of the well. Project cost was $225,086.00 Pump and drive: A 460 volt, 150 horse power Hitachi submersible motor was installed with a pump designed to pump 1,400 gallons per minute. Shortly after well #4 was put into service, it was found to pump sand when anything over 850 gallons a minute was produced. With no way to decrease the pump speed, because the pump drive is a soft start, the decision was made to partially close a downstream valve to limit the well pumping capacity to 850 gallons. This presents a couple of issues, increased electrical demand and a high pressure condition of 120 psi, between the pump and the partially closed valve. These concerns will be addressed in a future case in 2013. Well maintenance program: The City of Ramsey has taken a proactive approach on maintaining our eight municipal wells, since this is currently our only source of fresh water. In 2010 we added well rehabilitation to the Capital Improvement Program. Well use is highly variable throughout the year. Regular maintenance is scheduled during low demand periods to reduce the possibility that a well will be out of service when peak demand is required. Notification: Observations: On October 9th E.H. Renner & Sons pulled the 10" 130' drop pipe and the submersible pump and motor for well #4. The pump bowls were inspected and excessive wear was found on bearing surfaces and impellers. The 130' drop pipe was also inspected and severe pitting was found on the entire length of pipe. The pump motor was shipped to Submersible Motor Engineering in Phoenix AZ., where testing could be performed. Tests came back showing that the electrical windings are weak and the insulation is leaking too much to risk putting it back into service. The good news is that both the pump and the motor can be rebuilt. The drop pipe though must be replaced, including the check valve, which was also found to be leaking. Funding Source: This repair would be funded through the #9601 Water Enterprise Fund Staff Recommendation: Contract with: • EH Renner has provided a written quote of $18,843.00. This quote includes all parts and labor necessary to repair the pump bowls, replacement of all drop pipe, check valve, installation and start up assistance. • Submersible Motor Engineering USA has provided a written quote of $10,983.00. Quote includes parts and labor to make all necessary repairs to the 150 Hp. Hitachi 12" pump motor. Their quote also includes testing and a 12 month warranty.