Generally mini-trench and micro-trench methods of underground pipe or cable installation are categorised as trenching methods with a limited surface impact. The narrow trenches significantly minimise the amount of excavated material and surface reinstatement. In addition, the operation avoids the normal hazards associated with open trenches and avoids having people in excavations.
Mini-trench
Mini trenches are narrow trenches slightly wider than the cable/pipe, excavated into soils usually using chain saws or toothed wheel excavators. Typically, the narrow trench is 50 mm to 200 mm wide. Depths can vary with size of machine, up to 500 mm with handheld machines, 1200 mm for walk-behind machines and 1500 mm for machines fitted to types of tractors.
Micro-trench
Micro trenches are very narrow slots cut into roads with cutting disks usually for the installation of cables. Typically, the excavated slot is 20 mm to 60 mm wide and up to 600 mm deep. The specialised machines can use vacuum extraction of the excavated material and place the cable from a spool. The slots are usually backfilled with material with an added binder. Consideration must be made that the slot might introduce a weak joint in the road structure and shallow installations could be affected by future surface milling for road maintenance purposes.