Erosion of Sediment Beds in Sewers: Model Development
Publication: Journal of Environmental Engineering
Volume 125, Issue 6
Abstract
The problems created by sediment deposits in combined sewer systems (sanitary and storm) are internationally recognized. The loss in conveyance due to these deposits contributes to hydraulic overloading, leading to flooding and premature operation of combined sewer overflows. The washout of sediments through combined sewer overflows into urban water courses during times of storm and the associated pollution caused by this phenomenon may be a factor affecting many urban ecosystems. Based on field observations, coupled with sampling and analysis of combined sewer sediment deposits, it has been found that in the invert of pipes there is often coarse, loose, granular, predominantly mineral material overlain by a mobile, fine-grained deposit. The erosion of the latter type of deposit is considered to be the source of the “first foul flush” of pollution, which is observed in many sewerage systems in response to storm events. This paper describes an experimental laboratory investigation of the erosion and subsequent suspended sediment transport of an in-pipe, fine-grained, organic, cohesive-like sediment deposit analogous to those found in sewers. The development of the laboratory system, the test program, the results of the study, and the development of a new approach to model the erosion and transport of cohesive-like sediments in pipes are described. Conclusions regarding the importance of the structure of the bed and its erosional behavior under a wide range of time-varying hydraulic conditions are presented.
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References
1.
Ackers, J. C., Butler, D., and May, R. W. P. ( 1996). “Design of sewers to control sediment problems.” CIRIA Rep. 134, CIRIA, London.
2.
Ackers, P. ( 1991). “Sediment aspects of drainage and outfall design.” Proc., Int. Symp. on Envir. Hydr.
3.
Ashley, R. M. ( 1993). “Cohesive sediment transport and erosion in sewers.” Scottish Hydr. Study Group 1993 Symp. on Sediment Transport.
4.
Ashley, R. M., and Bertrand-Krajewski, J.-L. ( 1993). “Sewer sediment origins and transport in small catchments.” Proc., 6th Int. Conf. on Urban Storm Drain.
5.
Ashley, R. M., Wotherspoon, D. J. J., Coghlan, B. P., and McGregor, I. ( 1992). “The erosion and movement of sediments and associated pollutants in combined sewers.” Water Sci. and Technol., 25(8).
6.
Berlamont, J., and Torfs, H. ( 1996). “Modelling (partly) cohesive sediment transport in sewer systems.” Water Sci. and Technol., 33(9).
7.
Brownbill, V. R., Jackson, D. H., Douglas, I., and Crabtree, R. W. ( 1992). “Impact of storm sewage sediments on river quality.” Nat. Rivers Authority R&D Note 92.
8.
Crabtree, R. W. ( 1989). “Sediments in sewers.” JIWEM, 3, 569–578.
9.
May, R. W. P. ( 1993). “Sediment transport in pipes and sewers with deposited beds.” HR Wallingford Ltd. Rep. SR 320, Wallingford, Oxfordshire, U.K.
10.
Nalluri, C., and Ab Ghani, A. ( 1993). “Bed load transport without deposition in channels of circular cross section.” Proc., 6th Int. Conf. on Urban Storm Drain.
11.
Nalluri, C., and Alvarez, E. M. ( 1992). “The influence of cohesion on sediment behaviour.” Water Sci. and Technol., 25(8).
12.
Parchure, T. M., and Mehta, A. J. (1985). “Erosion of soft cohesive sediment deposits.”J. Hydr. Engrg., ASCE, 111(10).
13.
Ristenpart, E., and Uhl, M. ( 1993). “Behaviour and pollution of sewer sediments.” Proc., 6th Int. Conf. on Urban Storm Drain.
14.
Rouse, H. ( 1937). “Modern conceptions of mechanics of fluid turbulence.” Trans. ASCE, 102.
15.
Saul, A. J., and Ellis, D. R. ( 1990). “Storage tank design in sewerage systems.” Proc., 5th Int. Conf. on Urban Storm Drain.
16.
Skipworth, P. J. ( 1996). “The erosion and transport of cohesive-like sediment beds in sewers,” PhD thesis, University of Sheffield, England.
17.
Thornton, R. C., and Saul, A. J. ( 1986). “Some quality characteristics of combined sewer flows.” Public Health Engr., July 3.
18.
Verbanck, M. A., Ashley, R. M., and Bachoc, A. ( 1994). “International workshop on the origin, occurrence and behaviour of sediments in sewer systems: Summary of conclusions.” Water Res., 28(1).
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Received: Aug 25, 1997
Published online: Jun 1, 1999
Published in print: Jun 1999
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