Análise de projeto de sistema de esgotamento sanitário – estimativa de custo para diferentes valores de tensão trativa

Abstract

The increasing concentration of people in cities over time has brought to society problems hitherto unknown, such as the deficiency of urban infrastructure, the accumulation of waste and the inappropriate disposal of liquids, causing public and environmental health problems. Linked to this, cities began to observe the importance of basic sanitation as a way to mitigate pollution and the transmission of diseases. Over the years, it was realized that it was necessary to universalize basic infrastructure services and, in this respect, Brazil adopted a series of measures such as the enactment of laws and decrees, the creation of organs and, planning to effect the reality of basic sanitation in the country. However, this sector continues to present the largest deficit in terms expansion and attendance, due to the low quality of the services provided, connected too to the lack of more considerable investments. In this sense, this work is justified as an important aid in the search for the universalization of sanitation services, especially with regard to the collection and transportation of sanitary sewage from poor and rural regions, which often do not have the proper attention of the government and service providers. For this, it was performed out the conception, dimensioning and analysis of a sanitary sewer system project for the public allotment Miguel Arraes de Alencar, located in the city of São Vicente Férrer, in Pernambuco, with the objective of collaborating with the reduction of the discharge of these effluents into the environment without any type of treatment. The conception and dimensioning of the sewage collection network were performed with assistance of software CEsg, the analysis of the project was perfomed out based on the elaboration of 4 sizing alternatives with different values of minimum tractive tension 0,6 Pa; 1,0 Pa; 1,5 Pa e; 2,0 Pa. The analysis and selection of the most suitable alternative it was made out based on technical-economic criterion, as well as criterion related to the cost-benefit of the system, for that purpose, results and budget worksheet studies were carried out, made available by the CEsg in which it was observed that the alternative 3 (1,5 Pa) was suitable as the best project alternative, since it presented a greater balance in relation to the quantities and costs of the types of trench shoring, in comparison to the other alternatives. The results indicated that when comparing alternative 3 with alternatives 1 and 2, in which alternative 2 is the one indicated by the current regulation, the alternative 3 presented a considerable decrease of about 39,34% in your quantity of shoring of average cost and special type, as well as, only a small increase in the amount of shoring high cost and mixed type (67,81%). As for the analysis of the costs of the main services of this type of construction, the alternative 3 presented an increase of only 21,25% in relation to the first 2 alternatives, data that were not reached by alternative 4 what including considerably increased the cost its implantation when changing the tractive tension. Therefore, alternative 3, intermediate, was considered for the project, because, although a little more expensive than alternatives 1 and 2, an alternative 3, in addition to guaranteeing selfcleaning of the ducts, significantly decreases the chances of the appearance of sludge and, consequently, attack of sulfides in the pipe, what does not happen with alternative 2 indicated in the norm. Alternative 3 was chosen as the concept adopted, thus guiding the elaboration of its budget spreadsheet, as well as the elaboration of the necessary projects required for the allotment.