Upgrades to City Well #4

Construction for Municipal Well #4 began October of 1997 and construction was completed in April of 1998. The well has produced 1.6 billion gallons of water over its life span and has operated without problem. In the fall of 2012 the pump and motor were removed as part of our city well maintenance program. All needed repairs were made to the pump and the submersible motor in March of 2013. All Minnesota Department of Health mandated water tests have been completed and the well is back in service.

This particular well has a 460 volt, 150hp Hitachi submersible that runs a pump designed to produce 1,400 gallons per minute, however in April of 1998 the well was found to pump an unacceptable amount of sand at the 1,400 GPM rate. With no ability to decrease the pump speed, a decision was made to partially close a 10” butterfly valve in the well vault; allowing the pump to only produce 850 GPM. This rate allows the well to pump sand free. Pumping at this rate, however, presents a couple of issues, including unneeded electrical demand, a high pressure condition and unnecessary wear on the pump and motor.

Since the original installation in 1997, pump drives have improved greatly and most now are driven with a Variable Frequency Drive (VFD). The purpose of a VFD is to convert A/C power to D/C power and allow the operator to control the speed of the pump, thus eliminating the need to partially close a valve to control the flow. Another advantage of upgrading Well#4 with a VFD would be the ability to slowly ramp up the well and possibly allow the well to produce sand free water at a higher pumping rate than the current 850 GPM.

At the 11/20/2012 Public Works Committee meeting, committee member Elvig asked for a future case, with quotes on making the needed upgrades to this well when the well was returned to service. We have received two quotes for this upgrade and have also learned of a rebate that Connexus Energy has made available for VFD installations. The rebate would pay $30.00 per horsepower. Well #4 is rated at 150HP, so our rebate on the project, if we go forward with the installation, would be approximately $4500.00.

This upgrade would be funded through the #9601 Water Enterprise Fund

Staff recommends awarding the quote from Total Control Systems Inc. to make all the needed upgrades to this site to include all parts, labor, start up, and assistance with rebate application.

Motion to award the quote from Total Control Systems Inc. to make all the needed upgrades to this site to include all part, labor, start up, and assistance with rebate application.