Detention Tanks in Individual Terrains: Applications in the City of Goiania

The urban drainwatering stills a major challenge for most of the Brazilian cities. Not so different of the most part, Goiania, a state capital located in Midwest of the country, has few legislations about the subject matter and only infiltration wells as a registered solution of compensatory techniques for drainwater. This paper clam to show methodologies for application of detention tanks in plot level, through local boundary conditions in the city of Goiania. Were created models with adopted data for dimensioning the size of detention tanks using the rainfall method, the method developed by Aron and Kibler, the Rational Method and the Decree n. 23.940 from Rio de Janeiro, another Brazilian city. Were considered synthetic series for intense precipitations considering building sits with an impermeabilization tax of 75% and runoff coefficients based in the soil occupation. The use of detention tank showed practicable, have seen that the occupation of the tank is minor than 3.4% of the building sit in the more conservative methods, whatever the size of the terrain in the study. Was granted the exit flow to pre-occupational taxes in extreme rainfall events in the rainfall method. In the Decree method the results were far above of the pre-occupational exit flow, and the Aron and Kibler and Rational methods were similarly far below of the pre-occupational exit flows. Also, was developed linear equation for each method, to measure the detention tank based in the size of the building sit to Goiania, making simpler the calculation and implementation for non-specialized people. The choice of a methodology for wide use in the city and region must be based in technical-economic fators, and can be considered as an alternative in the Urban Drainage Master Plan of Goiania, wich is under development.