Analysis of City Sewerage Networks Operation

Summary

Results of the analysis of the data base on operation failures of sewerage networks of the city of Samara during the last 9 years of their operation are presented. From the point of view of reliability the gravity sewerage networks are the weakest element of the city wastewater disposal system. According to the statistical data the clogging is the cause of 99% of failures of functioning of the sewerage network. Most of the clogging (over 97%) happens at pipelines of up to 250 mm diameter. In the course of drawing up the schedules of planning-preventive works the operation departments should take into account the seasonality and pay particular attention to the sections of sewerage network with pipes of small diameter. During the reconstruction of gravity sewerage pipelines of less than 250 mm diameter it is recommended to use plastic pipes and pipes of larger diameter.

Key words

reliability , leak-proofness , sewerage network , clogging , damages

The reliability of municipal sewers

Summary

The aspects of the reliability of municipal sewers are considered. The reliable transportation of raw wastewater to the treatment facilities is extremely important for the normal town-living. At present there is no authorized quantitative index of sewer reliability. Municipal sewer is a comprehensive technical system and the reliability indices shall be designated as appropriate. The use of the mathematical model of such facilities provides for determining the complex of the sewer reliability indices. The factors that affect the sewer reliability are analyzed; specific measures of its improvement are suggested.

Key words

Failure , collector , mathematical model , clogging , reliability indices , sewer

Problems in sewer network operation and ways of their elimination

Summary

The main problems arising during the operation of sewer networks – blockages, network deterioration and odors are highlighted. The causes of their occurrence are considered and methods of their elimination are proposed. Under the conditions of Russia blockages are most likely to occur as a result of errors in design and erection. These are violation of the pipe turnout grade, pipe diameter mismatch, turnout grade fault because of soil movement, unsatisfactory state of sewer and pipeline failure. Design and erection errors and low cultural level of the users of the sewer system can lead to the emission of high concentrations of hydrogen sulfide. Any blockage in the sewerage system is accompanied by foul odor above ground that is explained by the emission of hydrogen sulfide. By using advanced computer aids it is possible to keep account of all the factors that affect the useful life of sewers. Systematization of the obtained data and its further use provide for extending the pipe life and reduce the expenditures for renovation and maintenance of sewers. The paper is written on the basis of designing and operating the sewer networks in Saint-Petersburg.

Key words

pipeline , odor , sewer , sewerage system , clogging , microbiologic corrosion , sewer network deterioration , soil failure