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REQUEST FOR COUNCIL CONSIDERATION Agenda Section: 19.__ o it Illi�II� STAFF Report Number: 95-1331WS III. %'?' May 1, 1995 Report Date: __-4__--2 =— - ------ AGENDA SESSION DATE DISPOSITION Item Description: Consideration of Booster Station Electrical Upgrade Administrator's Review/Recommendation: - No comments to supplement this rep -t - Comments attached. Explanation/Summary (attach supplement sheets as necessary.) UMIV luu A few weeks ago, staff met with Barb Biren, a representative from NSP, to discuss the City' s rate structure for the pump houses . By changing to a new rate structure and minor operational adjustments the City is forecasted to save an additional $3, 600 . Staff has approved the change in rates and is adjusting the operation schedule of the wells accordingly. In further discussion, staff also requested information about energy efficient motors, variable frequency drives (VFD) , and any other related data that could help the City save money related to the pumping of water. One of the topics which stood out as a very good energy saving device, and operational enhancement is changing to a VFD on one motor at the booster station. A VFD will provide for a constant level of water in the tower, during peak usage times in the summer. It will also ensure adequate pressure and volume for fire protection, while saving energy costs. Wear of the pump, motor, and starter will also be greatly reduced, saving repair, and maintenance costs. After further research, staff discovered that VFD' s are not available for motors exceeding 100 hp. at 240-volts . The City would have to change either the current motor (125 hp. ) to 100 hp. or upgrade the service to 460 volts . NSP offers both rebates for converting to high energy efficient motors ($12/hp) , and the installation of VFD' s ($70/hp) . The payback in electrical expenses for a VFD installed on a 100 hp. motor, would be less than two years according to computer models of our current operation. Staff and SEH are currently searching files to locate the pump curves for the booster pumps . This information will indicate whether changing motors and drives is possible and feasible . Additional upgrades will be required if it is determined that 100 hp. motors can not be utilized. Converting the standby generator and switching panel to 460 volts would also be necessary. Although this would be an additional expense to the City, the payback would be realized in future energy costs . These costs are unavailable at this time. NSP will pay for 750 of the engineering costs to determine if this type of upgrade is possible . If through the study, it is determined that converting to a VFD is not applicable for the City, NSP will still pay for their 75% . j ' ' 1YI + ..