The construction of sewers is often carried out using the open construction method. Depending on the design, this results in pipe-soil systems with different external loads on the sewer. To understand these relationships, the soil mechanical and hydrogeological principles for characterizing the subsoil are explained.

After completing this module, you will have a sound knowledge of how:

• to differentiate between soil types;
• to identify the influences of grain shape and grain size distribution on the practical construction properties of the subsoil and
• to name the different appearances of water in the subsoil;
• to determine the water permeability of the soil for a constructional assessment of the soil.