Abstract
Retention and settling basins represent important elements in management of urban stormwater rejections. These devices, used for settling of stormwater, were already the subject of two kinds of investigations concerning on one hand, more or less complex in situ experimentations and on the other hand laboratory experimentations as well as hydrodynamic modellings under controlled conditions and simple geome- tries. The results obtained in laboratory conditions remain hardly transposable to real systems because of many reasons: complexity of geometries, inlet and hydro- dynamic features variabilities, heterogeneity of sediment characteristics, etc. This PhD work was thus focused on both metrology and modelling of stormwater total suspended solids TSS settling problem in full-scale sedimentation systems. It was supported by the retention and settling basin experimental site Django Reinhardt at Chassieu (volume : 32000 m 3 , surface : 11000 m 2 ). Three main aspects have been treated in terms of metrology: the applica- bility of VICAS protocol for the assessment of settling velocities of sediments set- tled on the bottom of the device, the physico-chemical characterisation of settled sediments and the processing of the on-line data in order to estimate the pollutant loads at basin inlet and outlet. The Rubar 20 CFD software has been applied to modelling the 2D hydro- dynamic behaviour of the retention and settling basin. The work has been under- taken in two phases: the first one strictly hydraulic, the second one including solid transport. The results obtained by modelling of observed storm events suggest: (i) a good capacity of the model to predict the settling efficiency and (ii) similarities be- tween settling preferential areas predicted and observed in situ. However, the mod- elling of outlet TSS concentrations remains less satisfactory. The results obtained confirm the relevance of coupling metrology and modelling in order to improve the design, sizing, modelling and management of ur- ban stormwater retention and settling basins.
| Translated title of the contribution | Stormwater settling process within a full-scale sedimentation system: elements of reflection for monitoring and modelling |
|---|---|
| Original language | French |
| Date of Award | 25 Mar 2008 |
| State | Published - 2008 |
Keywords
- settling
- stormwater
- stream water
- full-scale device
- big size device
- metrology
- modelling