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<br />Facility Audit Report 9 <br />San Leandro WWTF <br />In addition, the air delivery piping system will be modified to allow a new low pressure blower <br />capable of delivering 400 SCFM to supply air to the offline basin, to maintain its diffusers in <br />operation. <br />Table 3.2.1.1 shows the baseline and estimated post-installation energy and cost parameters <br />used in estimating project energy and cost savings from the blower replacement EEM. <br /> <br />Table 3.2.1.1 Measure Savings Summary <br /> <br /> <br />3.2.1.1 Description of Findings <br />The venting of air to the offline basin is a significant source of energy waste. At the lowest air <br />demands, more air is vented than is used in the treatment process. On average, 24% of the <br />blower discharge was vented to the offline basin in 2010. This vented air is not completely <br />wasted – it keeps the diffusers in the offline basin operational while they are kept covered with a <br />foot or two of water. Operations staff prefer to maintain at least 400 SCFM air flowing through <br />the offline basin. However, the pressure required to supply the air to the offline basin is 1-2 <br />psig, due to the low water level covering the offline diffusers. Using 5+ psig process air and <br />dropping the pressure through a control valve wastes substantial energy, even at the preferred <br />400 SCFM airflow. <br />In the analysis that follows, the main focus is on the energy performance of process air supply <br />to the online basin. This serves our intent to propose supplying air to the offline basin from a <br />separate low pressure blower system. To simplify the analysis, we first assume all the baseline <br />energy demand is for process air, and the vented air is simply waste. From an energy <br />standpoint, this is virtually true, since most of the energy imparted to get the air to 5+ psig is lost <br />through the control valve regulating flow to the offline basin. <br />In Figure 3.2.1.1.1 below, the 2010 baseline process airflow demand and energy performance <br />of the existing aeration system is summarized. The flow frequency peaks at 2000 SCFM, and <br />most airflow demand is below 3500 SCFM. The power demand of the existing blowers is nearly <br />ItemBaselineProposedSavings <br />Blower System <br />Description <br />Three 150 HP <br />Multistage Lamson <br />Blowers <br />One 100 HP Turbo <br />Blower, One 10 HP PD <br />Blower, Two Multistage <br />Lamson Blowers- <br />Power Demand <br />KW max16915910 <br />Annual Energy <br />KWh844,000568,000276,000 <br />Blended Demand <br />Charge $/KW$209 $209 <br />Blended Energy <br />Charge $/KWh$0.100 $0.100 <br />Annual Power <br />Costs$119,500 $89,900 $29,600