Drain backfill (post-repair)

Drain backfill is the controlled refilling of a trench around a newly installed or repaired pipe, using bedding, surround and main fill materials specified in BS EN 1610 and Building Regulations Part H. Bedding is typically pea shingle or graded granular material, with selected backfill placed above the pipe in layers and compacted to avoid imposing point loads. Where the trench is in a highway, the upper layers will need to meet the relevant local authority specification, often referencing the Specification for the Reinstatement of Openings in Highways (SROH). Care must be taken to maintain pipe alignment during compaction, since poor backfill is a frequent cause of premature pipe failure. Air or water testing in accordance with BS EN 1610 should be carried out before final reinstatement.