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<br /> <br /> Bay Area Clean Water Agencies | City of San Leandro Final Report | 23 <br />Nutrient reduction is also calculated as the average of the 30 year life cycle analysis, based on <br />projected nutrient discharge loads under current operation versus the nutrient discharge when <br />meeting Levels 2 and 3. Unit costs (e.g., $/gpd) are also provided to present a normalized estimate <br />of the cost for comparison to other facilities. The unit costs include only the respective facilities and <br />costs needed to address ammonia, TN or TP reductions. <br />6.5 Ancillary Benefits and Impacts for the Plant Upgrades <br />Table 6-3 lists the ancillary benefits and impacts associated with the recommended plant upgrades <br />to meet the Level 2 and Level 3 nutrient targets. <br />Table 6-3. Ancillary Impacts for the Upgrades to Meet Levels 2 and 3 <br />Strategy Benefits Adverse Impacts <br />Level 2 · Additional primary clarifiers capacity <br />· Enhanced phosphorus and nitrogen load <br />reduction <br />· MBR produces higher quality product water <br />than current facilities <br />· Increased energy demand from MBR <br />· Additional process to operate <br />· Operate in a new mode that will require the <br />operators to get accustomed to <br />Level 3 Same as Level 2 plus the following additional <br />benefits: <br />· Further alkalinity recovery due to more <br />denitrification than the other Levels <br />· Further improved product water due to filtration <br />step <br />Same as Level 2 plus the following additional <br />adverse impacts: <br />· More chemicals required than Level 2 <br />· Additional solids <br />· Safety from external carbon source (if <br />methanol) <br />· Additional aeration basin volume to operate <br />· Operating an additional biological process (i.e., <br />sidestream treatment) <br />7 Nutrient Load Reduction by Other Means <br />The SLWPCP has an existing recycled water program that is employed year-round. This existing <br />program has the effect of reducing nutrients discharged to the Bay. The plant recycles approximately <br />570 acre-feet per year (185 million gallons per year). There are plans to further expand the recycled <br />water program up to approximately 710 acre-feet per year (230 million gallons per year). <br />8 Greenhouse Gas Emissions <br />The impact of any proposed unit processes on greenhouse gas (GHG) emissions is a requirement <br />under the Regional Watershed Permit. The permit GHG emissions requirements are not intended to <br />be a plantwide GHG emissions with indirect and direct emissions reporting. Rather, the intent is to <br />identify potential changes in potential energy and chemical demands if plants transitioned from <br />secondary treatment to nutrient removal. It is well documented that transitioning from secondary <br />treatment to advanced treatment with nutrient removal will most likely increase the plant wide GHG <br />emissions. The increase is attributed to a combination of additional energy required to oxidize and <br />reduce the various nitrogen species, filtration requirements, chemical demands for alkalinity and <br />phosphorus precipitation, and others. <br />The increase in energy, chemicals, and GHG emissions while transitioning from secondary <br />treatment to nutrient targets is plant specific due to varying water characteristics, technology