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Plan of Study for City of North Olmsted Phase I by Floyd Browne Group January 4, 2006 Performance Evaluation Floyd Browne Group recalculated system curve pump curve theoretical performance of the LeBern pump station. The system curve calculations may be found in Appendix F. As can be observed from the pump curve on Figure 3, the performance of one (1) pump and two (2) pumps operating simultaneously are within the observed metered pumping rates found during the drawdown test Performed on November 16, 2005. The addition of the third pump adds very little to the overall pumping performance of the station as shown on the pump curve drawing. However, this small increment is critical to prevent flooding of homes in the LeBern neighborhood even though the third pump uses more power and the pump sustains additional wear for very little return in pumping rate. As can be seen in the Appendix the wet well increase to 8-feet above the wet well invert did not show any abnormality on the system pump curve relationship. The increase in the wet well height showed an expected lessening of the total dynamic head in the system and plotted out as slightly more pumping capacity. Draw Down Test On November 16, 2005 a draw down test was performed to determine actual pump rates of the three flooded suction pumps at the LeBern pump station. The draw down test is performed by allowing the pump to lower the wet well level to a certain height. The volume of the wet well is then calculated using the square foot area of the wet well surface multiplied by the draw down height. If wastewater is flowing into the wet well during this period, the additional water into the wet well is taken into account and added to the total pumping rate. On November 16, 2005 there was a continuous flow of wastewater entering the wet well. This amounted to approximately 726 gpm. The north pump was tested first then the middle and tr7e south pumps. Finally the south and middle pumps were tested running simultaneously. The pumping calculations were then compared with the station meter. The results are listed below. 1. North Pump a.Draw down rate = 3.87 MGD b.Meter Observation = 3.09MGD 2. Middle Pump a.Draw down rate = 2.82 MGD b.Meter Observation = 2.77 MGD 3. South Pump a.Draw down rate = 3.31 MGD b.Meter Observation = 2.77 MGD 4. South and Middle Pumps a.Draw down rate = 4.44 MGD b.Meter Observation = 3.5 MGD There is a large discrepancy between the drawdown rate and the observed rate most likely due to the fact that the pumps were tested by ramping up the variable speed drives which made a single pumping rate during the ramp up period difficult to determine. By the time the pumps ramped up to 100% of the operating capacity the test volume had already been pumped. In 24