Trial trenching


This technique involves the excavation of exploratory trenches to ascertain the presence, condition and date of any archaeological remains which may be present. The technique is a rapid method of investigation, used to evaluate the archaeological potential of a site. 
Trench locations are often pre-defined by previous investigations such as aerial photography, geophysical survey or desk-based assessments or are targeted on known features in the landscape. The number of trenches that will be dug is based on a small percentage (usually 2-5%) of the total area of the site, designed to provide as much information about past human activity on the site as possible in a very cost-effective manner. The trenches are also often excavated in the footprint of proposed structures and infrastructure.
Large mechanical excavators are predominantly used to excavate the trenches, although they are sometimes dug by hand. All work is undertaken under the close supervision of experienced field archaeologists. Any archaeological features found will then be surveyed and hand excavated, sufficient to find out what types of remains are present, for example ditches or burials, and their date. 
The results of the trial trenching will determine whether any further work is required. For many sites a trial trench evaluation is sufficient to demonstrate no archaeological remains are present, and development can proceed. In other cases, further trenching may be required, or full excavation of certain areas of the site, or even an archaeological watching brief during construction.
Developers may be required to commission a trial trench evaluation of their site as a condition of the development Planning Consent.