Trial Pitting

The excavation of trial pits is a simple, cheap and reliable method of investigating soils and weak rocks at relatively shallow depths or rockhead at shallow levels.

Trial pits are also used to investigate shallow foundations, services, made ground and areas containing voids. Soil infiltration rates can be calculated in trial pits to aid the design of soakaways.

Typically, trial pits are logged by one of our Engineers. This involves a visual inspection of the excavation in terms of its stratigraphy, geology, groundwater level, stability, excavability, etc. Samples are taken and the pit is photographed before it is backfilled with arisings and left slightly proud to accommodate future settlement. Depending on requirements, the excavation can be backfilled in compacted layers, using an engineered fill, and the surface reinstated.

Trial pits can be excavated by hand or machine. In either case the process is not without its dangers. We aim to eliminate the risks as far as possible. It is therefore our policy that no person should enter any trial pit unless it is properly supported with shoring or the sides are battered back sufficiently. Any potential risk posed by poisonous or asphyxiating gasses must also be eliminated.