Report No FR0205

June 1991

I OBJECTIVES

1. To review current knowledge on the sources and characteristics of sediments in sewers and the behaviour of sediments in ancillary structures.
   
2. To identify necessary future research in these areas to support the ongoing development of sewer flow quality models.

II REASON

The current programme of sewer sediments research will come to an end in 1991/92. The results of this and other ongoing research are being used to develop MOSQITO 2, an enhanced version of the current sewer flow quality simulation model. It is anticipated that experience will dictate the need for further development of this model. This will only be possible if appropriate research and data collection programmes are identified and initiated with an appropriate lead-in time.

III CONCLUSIONS

The development of MOSQITO will require further research into the sources and characteristics of sediments in sewers and the behaviour of such polluted sediments in ancillary structures, such as storage tanks. This research will also be of considerable significance to developments in the cost-effective design of sewerage structures and the operational management and maintenance of sewerage systems.

In these areas of research, there are still significant uncertainties in the present level of understanding and a lack of good quality data. A considerable amount of research is underway outside of the UK into the behaviour of sediments in sewers and a ncillary structures.

IV RECOMMENDATIONS

The most fruitful avenues for further research will comprise joint field and laboratory studies to incorporate an integrated programme of research which looks at hydraulic, biochemical and rheological aspects of sediment characteristics and behaviour. The proposed programmes of research should be linked to other proposals for research to investigate the deposition and erosion of sediments in sewers. This research should be initiated within the next 12 to 18 months to permit a further stage of sewer flow quality model development and enhancement in the mid 1990s. If judged appropriate, a requirement specification for such modelling developments is required within a similar timescale.

V RESUME OF CONTENTS

This report consists of five sections.

The first describes the quality model within the UK Urban Pollution Management Programme. Sections 2 and 3 are reviews and recommendations for further research into the sources and characteristics of sewer sediments; and the behaviour of sediments in ancillary structures. Section 4 summarises the recommended research requirements. The final section is a comprehensive bibliography of the two review areas.

ACKNOWLEDGEMENTS

The main sections of this report are based on reviews undertaken by R M Ashley, D J Wotherspoon, I McGregor and B Coghlan (Nature and provenance of sewer sediments and associated pollutants) and A J Saul (Sediments in ancillary structures) under contract to Wrc.

The full report can be obtained on application to the Foundation

Copies of the report are available from FWR, price £35.00, less 20% to FWR Members.