This paper presents continuous field experiments carried out during 4 years in a man-entry egg-shaped combined sewer in Lyon, France in order to contribute to the knowledge and the modelling of sediment accumulation and sediment removal by means of a Hydrass flushing gate. The 250 microm sediments are mainly mineral, and their physical and chemical characteristics appear as rather stable in time and space. Long-term sediment monitoring reveals: (i) a regular asymptotic increase of both the sediment mass and the slope of its longitudinal profile, (ii) a clear correlation between local sediment profile irregularities and sewer ancillaries but without significant influence on the global and long term accumulation. Simple sediment accumulation modelling shows: (i) a good suitability of a three parameters conceptual model to reproduce asymptotic sediment volume accumulation, and (ii) a good suitability of the Velikanov model to reproduce sediment profiles. Both models reproduce observations with an acceptable margin of uncertainty for operational management purposes but are very sensitive to input data and parameter values. The Hydrass flushing gate is efficient and it appeared that the mass of sediments moves downstream linearly with the number of flushes.
[1]
Olivier Artieres.
Les depots en reseau d'assainissement unitaire : origine, caracteristiques, pollution, transport
,
1987
.
[2]
J L Bertrand-Krajewski,et al.
Hydraulics of a sewer flushing gate.
,
2003,
Water science and technology : a journal of the International Association on Water Pollution Research.
[3]
J. Bertrand-Krajewski.
Modelisation conceptuelle du transport solide en reseau d'assainissement unitaire
,
1992
.
[4]
L. Phan,et al.
Sediment transport model in sewer networks — A new utilisation of the Velikanov model
,
1998
.
[5]
A Campisano,et al.
Experimental analysis of the hydrass flushing gate and field validation of flush propagation modelling.
,
2005,
Water science and technology : a journal of the International Association on Water Pollution Research.