Detail design of sewer networks for Bahirdar and Hawassa towns in Ethiopia

Detaiied design of the sewer network. The network was dimensioned based on the flow rates calculated for the 2038 horizon population and wastewater production. The dimensioning of the network was also checked and provided for the flow rates for 2028 (10 years horizon) in order to be assured that the minimum velocity criterion (Hellenic Regulations Vmin=0.6m/s for minimum slope 0.3%) is satisfied. The network included gravity and pressure mains. The pressure mains from the Pumping Stations to the connection manhole of the gravity network for the 10 and 20 years horizon wss dimensioned and the flow characteristics calculated. In roads with wide or deep open, stormwater channels, a service sewer of 160mm minimum diameter was used to collect wastewater from private properties and was discharged to the main sewer as frequently as possible to the main sewer. Private connections were not a part of the detailed design since a typical drawing was used. However, provisions were achieved in the detailed design to ensure that all parts of the Network would be discharged to the Network