Methods and apparatus for cutting a trench (e.g., for a fiber optic cable or wire conductors) in an existing covering surface (e.g., a road surface). Debris from the cut trench is evacuated (e.g., vacuumed) from the trench as the trench is cut. The trench may be backfilled using a flowable composition. In one example, the flowable composition rigidifies after being flowed into the trench, and thereafter is substantially impermeable (e.g., having a hydraulic permeability of less than 0.0000001 cm/s upon drying), non-compressible and/or non-expanding.