Site Investigation

Unexploded ordnance

Unexploded ordnance (commonly known as UXO, sometimes referred to as UXB) is incendiary weapons (bombs, bullets, grenades, etc.) that did not explode when employed and still pose a risk of detonation. In the UK, the risk is mainly limited to London, Plymouth, Bristol, Manchester, Coventry and Birmingham, that suffered wartime bombing; and to sites used for training or to store ammunition.

When planning a new construction or civil engineering project, it is relevant to consider UXO risk assessments as part of the site investigation to determine the potential risks. The Construction Industry Research and Information Association (CIRIA) have published “Unexploded ordnance (UXO) – a guide for the construction industry” to provide advice on assessing the risk presented by UXO.

Two types of desk-based assessments could be undertaken. The first is a ‘preliminary UXO risk assessment’, which provides an initial screening report that includes a probability assessment of UXO risk. The second assessment is a ‘detailed UXO risk assessment’, which provides a more quantifiable risk assessment. It takes into consideration both the probability of the unexploded ordnance threat in addition to the potential consequences.