Trenchless excavation

Trenchless excavation describes any method of repairing or replacing drainage that avoids opening a full-length trench along the pipe. Techniques include pipe bursting, directional drilling, slip lining and CIPP relining, often combined with small access pits at chambers. The approach is increasingly required by London local authorities in conservation areas and on adopted highways, where surface reinstatement and traffic disruption are tightly controlled. Trenchless methods cannot be used in every situation, since severe pipe deformation, near-surface obstacles or short, isolated defects may still be cheaper to address by short open-cut excavation. CDM 2015 duties still apply to all access pits, and any works affecting the highway require a Section 50 licence from the relevant London borough.