Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/547956
18 WET NEWS AUGUST 2015 Much of São Paulo's underground sewer infrastructure has either stopped working or been abandoned, thanks to damage caused by urban improvement. Can it be resurrected to meet demand? The challenge: Coping with demand INSIGHT IT & TeleMeTry THE CONCEPT • SewerGeMS is an Urban Sanitary and Combined Sewer Modeling and Management tool • It can run within AutoCAD, ArcGIS, and MicroStation, or as a standalone application • It helped create several scenarios based on known information, such as interconnections of storm sewers and rainfall • It helped identify the best way to connect the abandoned sewer conduits to the existing system taking into account their elevation differences THE VERDICT "The reliability demonstrated by the results acquired through SewerGeMS is evident. Using SewerGeMS, Sabesp prepared simulations for various what-if scenarios to prove that the sewer system could meet demands even under extreme conditions." André Miguel, engineer, Sabesp S abesp provides water to and collects sewage from over half of the cities in the state of São Paulo, Brazil. This includes São Paulo the state capital and the country's largest city. The utility is upgrading the Anhangabaú sewer system, which consists of around 123km of sewer conduit network, with 1,749 manholes and 14,832 household connections serving an estimated 400,000 inhabitants. The system is located in an important historic area of São Paulo that is being impacted by urban sprawl; and because much of the government operates here and it is home to many hospitals, the area is under constant surveillance. During the past few decades, this region of the city has been through numerous urban improvements that heavily damaged the underground sewer infrastructure, to the extent that parts of the system stopped operating and were abandoned. Plans for a system upgrade were initiated and by using Bentley's SewerGEMS, Sabesp was able to design and develop a new collection system at a fraction of the initial cost estimate. Weather conditions Given the area's rise in population in the 30 years since the system was abandoned, Sabesp could not determine how the complex sewer system would react to the increased demand for water and sewage without using simulations. By creating a hydraulic model using SewerGEMS, Sabesp could simulate the demand and enable engineers to simulate the effects of various network and weather conditions. Sabesp engineers faced additional challenges with the large diameter (800mm) trunk conduits that were broken as a Urban sprawl has impacted the sewer system in Brazilian state São Paulo result of redevelopment works performed in Vale do Anhangabaú in the late 1980s; the creation of effluent discharge points that were polluting a major urban stream; and significant rain volume (inflow) from storm sewers and household connections feeding directly into the collection system. The major impediments to solving these challenges included the large investment in site works it would take to implement new conduits and the difficulty of performing these services in a busy, high- traffic region of the city. Moreover, the area is affected by poor quality subsoil layers, as well as an immense amount of interference from other subsurface utilities such as fibre optic cables, water pipelines, streams channeled into large galleries, and power transmission lines, among others. NEED TO KNOW 1 With broken sewer pipes, effluent discharges in water bodies, and high infiltration, the sewer collection system needed to be improved 2 A hydraulic model developed in SewerGeMS helped Sabesp engineers make optimal design decisions 3 The estimated project costs were reduced by more than 80% 4 The hydraulic model saved months of network assessment