Consideration on hydraulic reabilitation of accessible wastewater collectors

Accessible sewer collectors in service present a high degree of aging. Rehabilitation of accessible collectors can be differentiated by size and type of wastewater transported. Accessible sewer collectors (large and circular, ovoid, bell or mixed cross section) present specific measures for rehabilitation. Rehabilitation Technology can be with or without digging ditches. Accessible collectors may be rehabilitating with inner and outer works. Hydraulic rehabilitation requires flow parameters analysis for modified geometric sections. Hydraulic rehabilitation requires the analysis of collector walls roughness and its influence on the flow velocity. Research has indicated important changes to the flow section due to silting and hydrodynamic erosion processes. The flow sections were geometric transformed from curved shapes to mixed shapes (curves and lines).The changes of geometrical cross section caused the decreasing of velocity and transported flow by about 15 ... 28%.