after backfilling is completed and after the groundwater level has stabilized, the pipe should be checked for infiltration. All live inlets should be sealed and the line inspected from the manholes. Any flow from the pipeline coming into the manholes or within the manholes themselves should be investigated to establish its source.In small pipes, the point of infiltration may be located visually with light and mirror or with an inflated rubber plug. When conditions justify it a television camera can be used