Use of SWMM program and ATV 128 directives for dimension of sewer systems and stormwater tanks

The present theme handles the dimensioning of stormwater tanks with help of computer program SWMM and German ATV guidelines. This theme consists of two theoretical and a practical part. First part of theme presents the SWMM software (Storm Water Manegement model) which is designed for single event and long-term simulations of runoff quantity and quality in drainage system. Second part presents stormwater tanks and ATV-A 128 directives use for the dimensioning of stormwater tanks with overflow. Directives dictate procedure for determination of stormwater tanks with overflow's necessary storage volume. They require a lot of initial data which are need to be preliminary analysed. Necessary storage volume is determined by annual loading in overflow discharges into lakes or rivers. Concentracions of pollutants have to be within certain allowable limits. Third part of theme is a practical example. The sewage system of Šalek Valley has 30 stormwater overflows which discharge combined wastewater into lake and rivers. First flush of stormwater which is the most polluted, is need to be retained and fully conveyed to the treatment plant. The aformentioned drainage system does not include any of stormwater tanks which could perform these task. Therefore have I foresaw stormwater tanks in region Velenje – Šoštanj and determined theirs necessary storage volumes with the use of ATV guidelines and SWMM. I have made an outline scheme of stormwater tank with overflow Šalek II which could retain first flush of stormwater from the most part of the Gorica settlement between and after the percipitation event.