Choosing a technology for repairing sewers operated in difficult soil conditions with account of the geometric irregularity of the tunnel sections

Summary

Long-running sewer tunnels in large cities have a degree of deterioration of up to 55% or more. Difficult engineering-geological and hydrogeological conditions for tunnel laying, as well as intense anthropogenic impacts cause an increase in the defect rate of sewer tunnels. Based on calculations and hydraulic modeling, it is shown that with a high load of sewer tunnel networks and the impossibility to stop completely the transportation of effluents, the primary objective in choosing measures for repair and rehabilitation of tunnels is the search for technical solutions that provide for the maximum wastewater flow after the rehabilitation given the cross-section narrowing and geometrically irregular sections. The successful experience of SUE «Vodokanal of St. Petersburg» in the rehabilitation of sewers with narrowing sections without stopping the transportation of wastewater using technologies that meet these requirements is presented.

Key words

discharge capacity , operation reliability , sewer tunnel , complicated ground conditions , vibration strength , subsidence , cross-section narrowing , repair technology

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Mechanical Treatment of Wastewater at Sewage Pumping Stations

Summary

The most widespread methods of protection of pumping units against the ingress of large size garbage delivered to sewage pumping station with a wastewater flow are considered. An example of operation of the mechanized rake type screens RKE EKOTON® at the main sewage pumping station of the city of Seversk is made. The screens ensure the reliable removal of large size garbage from wastewater, owing to it the interrepair time of pumping unit operation increases. If before the reconstruction of the technological section 15–20 kg of garbage were removed from wastewater, after the adoption of new equipment this figure increased up to 50 kg/day. To compensate the costs of garbage evacuation the waste collected on screens is transported to the hydro-press for wringing that makes it possible to reduce it volume.

Key words

sewerage pumping station , mechanized rake type screen , filter fabric , discharge capacity