Retention-detention modelling of polluted stormwater runoff on sewage systems

The present theme handles retention-detention modelling of stormwater runoff on sewage system with help of computer program SWMM. The theme consist of two theoretical and a partical part. First part of theme presents the SWMM software (Storm Water Management Model) and its simulations of runoff quality in drainage system. Second part presents first flush effects, which occurs at the initial stage in stormwater runoff and carries with it concentrations of pollutants that have accumulated during the period of dry weather between storms, which could be one day or several months. First flush of stormwater is need to be retained and fully conveyed to the treatment plant. Third part of theme is a practical example. On sewage system was modelled first flushof stormwater and critical runoff, which occurs with 5-minutes storm. With foresaw of stormwater tank Šalek II in the sewage system of Šalek Valley we then did the simulation of retention polluted stormwater runoff. The comparison of the models confirm, that such a retention-detention device is one of the option for threating stormwater runoff and reducing first flush effects that can lessen adverse impacts on receiving waters.