Ord 1987-020 - Laserfiche WebLink

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wastewater treatment plant will be upgraded to treat the additional flow to allow it to service the entire basin area for the year 2005. Phase I of the system is designed primarily to provide service to the Lowmans' Ranch and Cottonwood Creek Park developments. This is where most of the initial development in the basin is projected to be located. The force main line from the central lift station to the existing wastewater treatment plant was designed to be constructed in two phases in an attempt to minimize the cost of the initial phase. The proposed alternative was designed so that parts of the system would not be completed until there was sufficient population growth in that area to warrant service. This allows the cost of the system to be incurred over a longer period of time J enabling the billing. to be better distributed to the people it serves. C. Sizing of Alternatives Using rough contours from the study area a preliminary route was decided upon for each interceptor line. The begimùng and ending depth of each line was calculated to determine if each line could maintain minimum depths as well as assure that sufficient slope would be provided for gravity flow. The average slope was then calculated for each pipe by subtracting the "out elevation" from the "in elevation" and dividing the total by the length. The design flow for each pipe was determined by assigning points of inflow at various locations along the interceptor. The total flow of each sub-basin was distributed in proportion to the location of the anticipated developments or flow requirements. The flow in any pipe consisted of the flow carried by the previous connecting pipe plus the amount of flow entering at the inflow point from the basin wheI'€ it was located. The minimum pipe diameters required for the gravity flow pipes were then determined by using the Manning JONES ð: II/EUSE 2C