Sewerage Network Design Project 2023-2024 PDF

Urban Drainage MSc Dr. Mansour Haidera 2023-2024 Sewerage Network Design Project The main objective of this exercise is to analyse the hydraulic performance o f looped water distribution networks with the help of a computer-modelling tool; SewerrGEMS softwar...

Urban Drainage MSc Dr. Mansour Haidera 2023-2024 Sewerage Network Design Project The main objective of this exercise is to analyse the hydraulic performance o f looped water distribution networks with the help of a computer-modelling tool; SewerrGEMS software. A2.1 INTRODUCTION – THE TOWN OF SAFI Safi is a town of approximately 16,170 inhabitants. Over the coming years, a rapid expansion of the area around the town is expected because of good regional development activities. A factory for production of agricultural machinery is going to be built near the town itself. The existing sanitation system just onsite with soak pits and in a very poor condition, and the construction of a completely new sewerage system has been proposed. An international loan was requested and has been approved. A separate sewerage network is planned for the construction. The planned design period of the new distribution network is 30 years. Based on the evaluation of the present situation and the estimates for future growth, a technically and economically acceptable solution for construction of the network has to be proposed. A2.1.1 Topography Safi is a secondary town located in a hilly area with ground elevations ranging between 8 and 28 msl. Figure A2.2 shows the configuration of the terrain together with the layout of the main streets in the urban area (dotted lines). A2.1.2 Population distribution and future growth The town is divided into six districts (A–F, in Figure A2.1), each of a homogenous population density. The total surface areas of the districts and sub-districts are given in Table A2.1. The present population density for each area, expressed as the number of inhabitants per hectare, is shown in Table A2.2. In the absence of more reliable data, the indicated population growth is assumed to be constant throughout the entire design period. 1 Urban Drainage MSc Dr. Mansour Haidera 2023-2024 Table A2.1. The town of Safi: surface area of the districts and sub-districts. District Area (ha) District Area (ha) District Area (ha) A 0.83 C3 0.5 D3 0.8 B 0.31 C4 0.84 E1 0.97 C1 0.74 D1 0.37 E2 1.2 C2 0.81 D2 0.56 E3 0.83 F 0.3 Table A2.2. The town of Safi: population density and growth. District Present (inhab./ha) Annual growth (%) A 2250 3.3 B 2480 3.3 C1,2,3,4 1860 3.3 D1,2,3 2020 3.3 E1,2,3 1440 3.3 F 1150 3.3 2 Urban Drainage MSc Dr. Mansour Haidera 2023-2024 A2.1.3 System layout The distribution pipes will be laid alongside the main streets of Safi. The network layout is shown in Figure A2.3, with the lengths of the sewer routes as indicated in the figure. The intersections (junctions) are numbered which can serve as manholes, and when needed additional intermediate manholes can be put with space as specified in the design criteria. Connection of the factory to the system is planned to be in Junction 01. Regarding 3 Urban Drainage MSc Dr. Mansour Haidera 2023-2024 the local situation (soil conditions, local manufacturing), PVC has been chosen as a sewer material for the network. A2.1.4 Water demand and leakage The water consumption in the area is mainly domestic, except for the new factory that will also be supplied from the distribution system. In the new system, the domestic consumption per capita, including leakage, is planned to be 200 l/d. In addition, the projected water demand of the new factory is 1500m3/d. The typical diurnal domestic consumption pattern is shown in Figure A2.4. Variation of the consumption during the week is within the range of 0.95 and 1.10 of the average daily figures. In addition, the monthly (seasonal) variations are in the annual range of between 90% and 115% of the average consumption. The factory will be working at a constant (average) capacity a day. A2.2 QUESTIONS A2.2.1 Hydraulic design a) Using Excell Program  Calculate the local population at each manhole at beginning and the end of the design period.  Calculate the local average flow rate at each manhole at beginning and the end of the design period.  Calculate the local maximum flow rate at each manhole at beginning and the end of the design period using the given consumption pattern factors.  Calculate the local maximum flow rate at each manhole at beginning and the end of the design period using Babbit Equation.  Calculate the local average infiltration at each manhole at beginning and the end of the design period. 4  Urban Drainage MSc Dr. Mansour Haidera 2023-2024 Network layout and design b) Using SewerGems software schematize the sewer network as discussed in section A2.1.3 taking into consideration the location of the wastewater treatment plant (WWTP). c) Using SewerGems software design the sewer network taking into consideration all the required design criteria discussed in the course. Presentation of the result d) Present the result of manholes and sewers in terms of tables and figures. e) Draw the sewers profiles and export them to AutoCad or Civil 3D. Summary f) Draw conclusions based on the hydraulic design of the system throughout the entire design period. Explain the phased development of the system, if applied. g) Mention any difficulties faced during the design and explain how did you tackled that. 5