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Section 2 <br />User Characteristics <br />I • r r r• r i/ • r • <br />Listed in the table below are flows and BOD/SS concentrations for each customer class that are used to <br />develop wastewater rates. Residential customer class wastewater flow is based on metered winter water <br />use. Commercial customer classes wastewater flow is based on metered potable water use. Industrial <br />User wastewater flow is based on effluent meter measurements. Flow from Inflow/Infiltration (1/1) is <br />based on a comparison of summer and winter flows to the City's Water Pollution Control Plant (WPCP).2 <br />All flow data is for FY18. <br />Residential wastewater BOD/SS concentration estimates for the Residential customer class are based <br />on a mass loading analysis.3 Wastewater BOD/SS concentration estimates for Commercial customer <br />classes are based on data gathered by other wastewater agencies. Industrial User wastewater BOD/SS <br />concentration are based on sampling and analysis of wastewater discharge from each user. Wastewater <br />BOD/SS concentration estimates for 1/1 are based on data gathered by other wastewater agencies. All <br />BOD/SS concentration data is for FY18. <br />Residential <br />Single family <br />Multiple family <br />Nonres <br />Auto, Steam cleaning <br />Bakeries <br />Laundries <br />Markets & foods <br />Mixed Use <br />Restaurants <br />Other Commercial <br />Institutional <br />Schools <br />Industrial <br />Inflow/Infiltration <br />Numberof Flow Strength <br />Billing Average Data BOD SS Data <br />Units gpd/Unit Source mg/L mg/L Source <br />14,142 145 wotermeter 300 320 moss looding <br />4,243 121 wotermeter 300 320 analysis <br />63 <br />680 <br />wotermeter <br />1,000 <br />1,100 <br />3 <br />74 <br />wotermeter <br />1,000 <br />600 <br />23 <br />3,024 <br />wotermeter <br />450 <br />240 <br />34 <br />1,026 <br />wotermeter <br />800 <br />900 <br />265 <br />333 <br />wotermeter <br />800 <br />800 <br />97 <br />968 <br />wotermeter <br />1,000 <br />600 <br />1,182 <br />611 <br />wotermeter <br />300 <br />320 <br />31 1,180 wotermeter 300 320 <br />20 26,649 effluent meter 1,574 605 <br />1 210,046 estimated 20 60 <br />data <br />generated by <br />other <br />wastewater <br />agencies <br />lob analysis <br />estimated <br />2 Inflow is stormwater that enters into sanitary sewer systems at points of direct connection to the systems. Various sources <br />contribute to the inflow, including footing/foundation drains, roof drains or leaders, downspouts, drains from window wells, <br />outdoor basement stairwells, drains from driveways, groundwater/basement sump pumps, and even streams. Infiltration is <br />groundwater that enters sanitary sewer systems through cracks and/or leaks in the sanitary sewer pipes. Cracks or leaks in <br />sanitary sewer pipes or manholes may be caused by age related deterioration, loose joints, poor design, installation or <br />maintenance errors, damage or root infiltration. <br />3 A mass loading analysis compares the amount of BOD and SS treated at the City's Water Pollution Control Plant with the <br />amount of BOD and SS discharged by Residential customers, Commercial customers, Industrial User customers and added by <br />Inflow/Infiltration. <br />