Sometimes iron and steel sections have been used where small repairs were necessary. Sewers are not however indestructible. Over time heavy earth and traffic loads, corrosion from chemicals and sewer gasses, and loss of supporting soil weaken the pipe. The traditional method for repairing a failed sewer is excavation and replacement. Excavation is often expensive and can be extremely disruptive to traffic and pedestrians.
Excavation can also be dangerous, and worker safety is always an issue.
Some communities are rehabilitating their sewers because of continued maintenance problems. An ongoing rehabilitation program helps minimize catastrophic failures by identifying and systematically rehabilitating at risk sewers. This controlled rehabilitation reduces disruption of the citizens through planning, preparation, scheduling, advanced funding, and design. Thin wall Odor during curing. May have greater material cost than other systems.