Evaluations are often undertaken prior to a development being approved and may comprise the excavation of a series of long and narrow trenches or smaller test pits, usually with a mechanical excavator. This is a rapid method for investigating the potential of a site. Any archaeological deposits encountered will be recorded and hand excavated.
The aim of the evaluation is to excavate and assess enough of the deposits to characterize and date them – and allow the local authority planning archaeologist to make appropriate recommendations for archaeological planning conditions (if any) that should apply. It is always the intention to leave as much of the archaeology undisturbed as is possible.
In order to characterize and date deposits, a programme of post-excavation assessment is undertaken.
On some sites, a geophysical survey or aerial survey is undertaken prior to evaluation trenching. The results of any survey are often used to position the evaluation trenches.
A report on the findings is then prepared for the client to submit to the planning authority. The results of the trial trenching may lead to several outcomes including:
- further excavation;
- the implementation of other conditions, such as a mitigation strategy;
- a watching brief during construction, or
- ending the archaeological requirement.