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Final Report <br />City of Paris, Texas <br />Wastewater Collection System Capacity Analysis <br />Components of Flow <br />Average Dry Weather Flow <br />Average Dry Weather Flow (ADWF) is the average flow volume and shape <br />that occurs on a day that is not influenced by rainfall. Selection of the dry <br />days to develop the ADWF is important since this synthetic day becomes the <br />basis of wet weather calculations. Wet weather responses are the deviations <br />from the Average Dry Weather Flow or ADWF. Average dry weather flow <br />is determined by selecting days on which several conditions are met. These <br />are: <br />• Less than 0.10 rainfall occurred on the day (minimar respo. rhreshora) <br />• Rainfall did not occur in the preceding 3 days with more than 0.40 inches <br />Of CU111L111t1Ve flOWS (minimal antecedent conditions) <br />• Rainfall did not occur in the preceding 5 days with more than 1 inches of <br />CU1T1111c1t1Ve flOWS (minimal antecedent conditions) <br />• Flow volumes were within a specified range (Not less than 85% of <br />average or mare than 115% of average) (mr,,;mar aeviar,o„from orher dry aays) <br />The day of the week is also considered, since significant changes may occur <br />in the flow patterns from day to day. Once the dry days are determined, the <br />average volume and composite diurnal shape for each of the metered basins <br />was calculated. <br />The Average Dry Weather Flow is composed of two components. These are <br />Wastewater Production and Base Inflow and Infiltration. These two <br />components are discussed in the following section. The relationship is <br />shown in the following formula: <br />Average Dry Weather Flow = Wastewater Production + Base Inflow and Infiltration <br />or ADWF = WWP + BUI <br />Wastewater Production <br />Wastewater production (WWP) is the actual wastewater flow that is <br />generated as a result of water use. The volume of the wastewater <br />production is a function of the population and land use of the area. It is <br />also strongly related to the actual water consumption in the area. <br />To generate Wastewater Production based on water records alone is <br />inherently difficult due the averaging of monthly flows and the seasonal <br />variations in "return-ratios". As a result, other methods for determining <br />Wastewater Production and its counterpart Base Inflow and Infiltration <br />have been developed. The relationship between the average flow volume <br />6 <br />