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Drainage Planning for Winden

The engineering office F&L GmbH planned the entire drainage facilities for the municipality of Winden in the Elztal region of Baden-Württemberg. The municipality contracted F&L to provide an overall approvable design of the future waste water and surface drainage facilities, taking state-of-the-art hydrologic and hydraulic computer-based calculation methods into account, as new building land was to be created and the bypass B 294 was to be extended.

Longitudinal profile with capacity utilization check ...... and variation comparison.
Longitudinal profile with capacity utilization check ...
... and variation comparison.

Logging the Existing Conditions

The sewer network of the municipality of Winden consisted of various partial networks; the wastewater and the rainwater were mainly drained into a separated sewerage system or otherwise into a combined wastewater system. The surface water is drained into the river Elz, the wastewater and the combined wastewater are fed into the sewage treatment plant in Niederwinden.

The approved land development plan and the old designs were the basis for the new design. In addition, BGRUND data and the plans of the existing sewers were available. These plans (manholes, missing topography) were digitized and supplemented by surveying whenever required. The total catchment area of the built-up areas was 55 hectares. A further 22 hectares were to be created.

Hydraulic Calculation

The hydraulic calculation (performance and overload calculation) was run using variable runoff coefficients according to Prandtl-Colebrook and the precipitation values of the DWD (German Weather Service). This data was used to create alignment related sewer profiles to display the capacity utilization of the individual reaches of the sewer. The graphics immediately showed where there were overloads and why. It was recommended to replace the reach in the near future to avoid such overloads.

It was also checked whether a future specific land-use area could be developed when taking the hydraulic calculation results into account. The value for the paved areas was increased, the hydraulic calculation was re-run and the results were visualized in the profile. The results list also contained suggestions on how to correctly dimension the sewer pipes.

Separated Sewerage Systems for Rainwater and Combined Wastewater

The municipality of Winden has 2,855 inhabitants. Based on the total area of 55 hectares, the population density was determined. These values were used to calculate the wastewater sewerage system. There were also 765m of sewer exclusively used as a combined wastewater system in the district of Niederwinden. As it was not necessary to drain the rainwater portion in this combined wastewater system into the sewage treatment plant in Niederwinden, the municipality decided to introduce a separated sewerage system here. Thanks to the hydraulic calculations and the sewer profiles with two colour-coded capacity utilizations, or water level lines, it was possible to calculate the rainwater balance in the combined wastewater system. As the portion of the rainwater is now known, a rainwater sewer could be planned without any further calculations to reduce the amount of water drained into the wastewater sewer and the sewage treatment plant.

One-stop Job

The results list with all input parameters, the sewer profile and the base map were part of the hydraulic calculation results. All plans were easily created based on reusable drawing specifications to create sewer base maps. When asked by the municipality, F&L not only visualized the overloads in the sewer profiles but also in the base map for a better overview.

The one-stop job accomplished with card_1 enabled the engineering office F&L to hand over a comprehensive and state-of-the-art drainage planning to the municipality of Winden. It confirmed the drainage situation and served as a guideline for necessary extensions and upgrades from a hydraulic perspective.

Project facts:

  • Overall drainage planning in Winden, Baden-Württemberg
  • 2,855 inhabitants, catchment area with built-up areas 55 hectares, 22 hectares of future specific land-use area