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City/of St. ;Anthony <br /> Page 2" <br /> December 24, 1986 <br /> 3. The pumps do not appear to deliver flow up to their rated <br /> capacities. The exact reason for this is not known at this time, <br /> however, it may be due to worn pumps, excessive forcernain <br /> headloss, inaccurate flow metering, greater static pressures or some <br /> combination of reasons. <br /> 4.' The 'pumps cycle on and off more often than is normally desired; <br /> approximately 10 times per hour. <br /> 5. The 'lif-t' station is periodically subject to high grit loadings which <br /> cause packing, shaft and impeller wear of the.pumps. <br /> Scope of Services <br /> Engineering services associated with the lift station feasibility study and <br /> cost evaluation would consist of the following items: <br /> 1. Investigate accuracy of existing flow. meter by comparing lift <br /> station fill and empty cycle to flow meter readings. If the existing <br /> meter is sufficiently accurate for design requirements, obtain flow <br /> records from the Metropolitan Waste Control Commission. Review <br /> flow data with the-Public Works Director. <br /> 2. If the existing flow meter is inaccurate, RCM will install temporary <br /> • flow meters near the lift station to determine actual flow <br /> quantities. The temporary metering data- will be correlated to the <br /> physical fill and draw calibrations and the MWCC flow meter data. <br /> A calibration of the pump capacity over its operating range would <br /> be made. Extended period flow estimates would be made by <br /> multiplying pump run times by the'calibration data, and compared to <br /> the temporary flow metering. <br /> The temporary flow monitoring would remain in operation for <br /> approximately two months. It is intended to measure the waste- <br /> water flow during both the "dry" winter periods, and "wet" spring <br /> snow melt/runoff times. <br /> w data is obtained at the lift station, projections of <br /> 3. Once reliable flow P 1 <br /> the anticipated future wastewater flow will be made, considering <br /> the P resent and anticipated future development of the area- being <br /> served. <br /> 4. Static and dynamic pump head conditions will _be checked, and <br /> compared to standard manufacturers pump curves for the existing <br /> pumps. If possible, original pump submittal data will be obtained <br /> and compared-to operating data. <br /> 5. If it appears that high- headlosses occur within the forcemain, the <br /> City will be requested to insert a pressure gauge in the pump <br /> • discharge line to enable monitoring of the pump discharge pressure. <br />