ABSTRACT
Most sewers are constructed underground. This is achieved by one of three general methods:
• open-trench construction • tunnelling • trenchless construction.
Open-trench construction consists of excavating vertically along the line of the sewer to form a trench, laying pipes in the trench, and backfilling – see Fig. 14.1. It is suitable for a wide range of pipe sizes and depths, and is the common method for small-to medium-scale sewer construction.
