Hydraulic capacity analysis of an existing combined sewer system using storm water management model

Abstract

Most of the sewerage systems in N. Macedonia is said to be separation, but in reality, they are most often combined systems where in the fecal sewerage system there are large number of connections from the storm sewer system, which practically in case of heavy rain with low intensity occurs overflow of the fecal sewage system. Also, with the increasing investment in the construction of wastewater treatment plants, the problems with mixing the sewage water are problems for the functioning of the treatment plants themselves. The subject of this paper is to make a hydraulic model using the software package SWMM to determine the hydraulic characteristics of a combined sewer system at the appropriate intensity of rain from where will be defined: the maximum amount of water that will come to the wastewater treatment plant, bottlenecks of the existing network, amount of water that will flow through the overflows, points of overflow of the sewerage, etc. The case study that was used to create the hydraulic model is for the city of Bitola. There are various methods for determining the amount of atmospheric water - the authoritative rain that will be used for analyzing the existing sewerage or will dimension the future sewerage, and in our country the most commonly used method is method of prof. Gorbachev because it is quite useful when the analysis does not use a sophisticated mathematical model. However, in this paper a comparative analysis will be made where besides the method of prof. Gorbachev will use the Rational Method.