WATR7104: Sewer SystemsAssignment#2Sewer Management ProblemA sewer system collects wastewater from an area that has got, in addition to large blocks ofresidential buildings, two big industries, one brewery and another a juice factory. The wastewatercollected at a pump station therefore consists of a significant portion of untreated industrialwastewater. From the pump station, the wastewater is pumped into a 5 km long rising main sewer,which discharges onto a gravity sewer. Due to the topographical feature of the area, the rising maindischarge drops from a height of 7 m before the sewage enters the gravity sewer causing significantturbulence. The discharge manhole is located close to a residential area. The gravity sewer is 5 kmlong, receives sewage from a number of branch sewer in addition to the above rising main anddischarges the sewage into a wastewater treatment plant. The gravity sewer is laid at a steep slopethroughout its alignment due to the topography of the area.A gas treatment unit was installed at the rising main discharge location to collect and treat the airfrom the headspace. However, due to the overloading of the system, the performance of thetreatment unit has been very poor for past several years. Also, the air extraction rate has alsosignificantly reduced due to mechanical problem. There have been a number of odour complaintsfrom residents living around the sewer alignment, and as a response to these complains, the utilityhas sealed all the openings along the sewer manhole except the drop manhole. Several structuresalong the alignment have been severely corroded.You have been hired by the utility as a consultant to carry out a desktop study and recommendsolution to the existing problems. You are expected to analyse the situation and providesuggestions for maintenance/rehabilitation of the sewer system as follows:1. Analyse potential problems and possible causes2. Suggest measures to mitigate the identified problemsThe outcome of this study needs to be presented in a form of a report.
