The largest sewage system of Latin America

The new sewage system in Buenos Aires, the capital of Argentina, with 14 million people in its metropolitan area, will discharge the city's effluents 10 kilometers from the coast.
The Riachuelo stream basin, which is a continuation of the Matanza river, is one of the most polluted urban basins in Latin America. The plans to solve this problem have happened without any of the proposed projects being carried out. At the present time, a large project called the Riachuelo System is being carried out, which will involve the construction of a Mega Collector consisting of more than 30 km of tunnels that will collect sewage along the left bank of the Riachuelo and transport them to a wastewater treatment plant. pre-treatment whose effluents will be dumped into the river 10 kilometers from the coast. This emission will be carried out through a 4-meter diameter tunnel dug below the water's bottom. This discharge will be made through diffusers inserted in the last kilometer and a half of the tunnel. The discharge point will be located 10 kilometers from the coast at the height of Avellaneda and 37 kilometers from the city of Colonia and it is not considered that there may be any transverse flow in the estuary that endangers the coastal waters in this Uruguayan city. 
Geographical data 
The Matanza-Riachuelo basin is located northeast of the province of Buenos Aires. The Northwest limits with the Reconquista river basin, the Southwest with the Salado river basin, the Southeast with the Samborombón river basins and the upper Río de la Plata slope, and the Northeast with the Río de la Plata. approximate length of 60 km and a general direction Southwest-Northeast, and an average width of 35 m, covering an area of 2200 km² up to the mouth of the Río de la Plata. In the basin, of 2,240 km², around 3,500,000 people live. It comprises part of the city of Buenos Aires and the municipalities of Almirante Brown, Avellaneda, Cañuelas, Esteban Echeverría, Ezeiza, General Las Heras, La Matanza, Lanús, Lomas de Zamora, Marcos Paz, Merlo and San Vicente. Its dominant topographic features clearly present three defined areas: high plain, intermediate plain, and low plain. Its name since its birth is Matanza River. From the Noria bridge where Gral Paz avenue begins, where it begins to delimit the city of the province of Buenos Aires, until its mouth its name is Riachuelo. The southeast, a storm periodically caused by strong southeastern winds, prevents the flow of its flow to the Río de la Plata, causing repeated flooding in the Buenos Aires neighborhoods of La Boca and Barracas (the two lowest neighborhoods in the city) . Since 1995 works have been carried out to prevent these problems. Your course receives numerous industrial wastes, especially heavy metals; and sewage from the saturated waters of the entire basin. Recently, several studies warned about the serious consequences of pollution in the population, especially children. Its main tributaries are the Cañuelas, Chacón and Morales streams in the province of Buenos Aires and the Cildáñez (tubed) in the Autonomous City of Buenos Aires. All these water courses are highly contaminated. 
The Riachuelo System 
 In recent years, a project called El Sistema Riachuelo has begun to develop, it is the first major expansion of the trunk sewer system that has been carried out in the Buenos Aires metropolitan area in more than 70 years. It is a mega infrastructure project that seeks to solve the sewage transport capacity in the metropolitan area, and whose main objective is to avoid contamination of the Riachuelo by sewage effluents. It is said that it will improve the provision of the service to more than 4.3 million people and, in the future, incorporate 1.5 million residents into the sewer network. 

The Riachuelo System is made up of three major works: The Mega Collector: more than 30 km of tunnels that will collect the sewage along the left bank of the Riachuelo and will transport them to the Pre-treatment Plant. The Pre-treatment Plant: which is being built in Dock Sud, Avellaneda, and will treat the liquids received from the Mega Collector. El Emisario: a tunnel that will be 4 meters in diameter is being built below the river bottom and will dump the liquids already treated into the Río de la Plata, 12 km from the coast. In 2020, the stage of driving the 34 diffusers into the last kilometer and a half of the tunnel which is beginning now, will discharge the effluents into the Río de la Plata, 10 kilometers from the coast. The effluent discharge point is located about 37 kilometers from the city of Colonia and everything seems to indicate, according to what we know about the dynamics of the Río de la Plata in that place, it has observed until now of any possible cross currents that could put at risk neither the water intakes nor the beaches of the city of Colonia and other points of this uruguayan department.