Is there a specific depth where battering / benching must be used when a trench is being excavated? Also, to save me trawling through google etc, could anyone recommend a source of simple and straightforward guidance on excavations for me? Whilst I'm on the subject - I know the guidance states that inspections of excavations should be carried out by a competent person - is there an industry standard that defines what a competent person is with regard to this specific subject? Thanks FH

There is no specific depth where battering, benching or trench supports must be used. It is dictated by the risk of injury or death following a collapse and which is influenced by the ground conditions, depth, imposed loads, water levels, competence/capability of the contractor etc. If you are in stiff ground with no imposed loads at unbuttered/supported depth of about 0.5m can be achieved without unacceptable risks. Some go deeper. Even at a depth of 0.5m a collapse of free flowing ground, sands or gravels can result in a broken ankle. Years ago there was a HSE guidance of 1.2m, but this has been retracted. The competence of the inspector tends to be in proportion to the complexity of the battering, benching or trench supports. Some excavations for example those on Crossrail are substantial and complex but a substantial number a straight forward.

There has been a tacit agreement in construction/utilities that any excavation above 1.2 metres does not need support - clearly this is not always the case. The substrate, prevailing weather conditions, potential for vehicles, etc, will determine whether support is required. In my experience there should be a person who is designated a Temporary Works Designer/Supervisor. I do not believe it is a legal requirement but good practice. Many organisations insist these positions are inbedded in the project team. HSE guidance - http://www.hse.gov.uk/co...tytopics/excavations.htm