Be careful what you dig for

Beginning a project in an area of archaeological interest can be an historical minefield for both developers and contractors.

Any damage to a "Scheduled Monument" as determined by the Secretary of State is an offence under the Ancient Monuments and Archaeological Areas Act 1979. Consideration of the history of the site is crucial in urban areas where there has been known historic settlement, but even for projects in more rural areas consideration must be given as to whether a development site may contain prehistoric bones or be a site of historic importance, such as a battlefield. Discoveries of human remains or metallic objects on the site of nationally important monuments should be screened to determine if they are subject to the terms of the Burial Acts or the Treasure Act 1996. So what does this mean for large and far reaching projects such as Crossrail and the Thames Tideway Tunnel ("TTT") and what can be learnt from them for smaller developments, particularly in areas of historical interest such as London?

The National Planning Policy Framework (“NPPF”) provides guidance on the basis on which local planning authorities may grant planning permission for historic environments: "as a minimum, the relevant historic environment record should have been consulted and the heritage assets assessed using appropriate expertise where necessary. Where a site on which development is proposed includes or has the potential to include heritage assets with archaeological interest, local planning authorities should require developers to submit an appropriate desk-based assessment and, where necessary, a field evaluation." If a developer's initial assessment of a site finds that uncovering items of archaeological interest is likely then the developer must submit a scheme to deal with any discovery which will become a condition of the planning permission.

Although many standard forms contain mechanisms by which a contractor could claim an extension of time for delay caused by archaeological finds it is common for developers to look to omit these and pass responsibility for the ground conditions onto contractors, who are also responsible for the programme. It is therefore imperative that the responsible party has detailed information about the risks of encountering artifacts and a scheme in place for if that risk materialises.

Both Crossrail and the TTT have frontloaded archaeological investigation and have prepared detailed schemes to deal with known and unforeseen areas of historical interest. Crossrail currently operates over 40 worksites and archaeological investigations will be carried out at each site ahead of the main construction works to build the central stations. An archaeological strategy (known as the Generic Written Scheme of Investigation) was prepared in consultation with English Heritage and County and local authority archaeologists to ensure a consistent approach across the route and throughout the life of the project. Crossrail also employs a team of archaeological specialists.

The TTT project has already published its Code of Construction Practice and an Overarching Archaeological Written Scheme of Investigation ("OAWSI"). The obligations on the contractor as regards the historic environment are set out in some detail. Contractors undertaking the work will be obliged to prepare a site-specific heritage management plan which must also include procedures for unexpected archaeological discoveries during the works and an emergency preparedness plan. The OAWSI states: "Where possible the intention is to take archaeological mitigation off the construction critical path and carry out as much work as possible prior to main construction activities commencing". By frontloading archaeological investigation and planning both projects have sought to mitigate delay and actively conserve historic environments.

What we can learn from big projects which take a proactive and stance regarding archaeology is that, as ever, preparation is key. Whether a developer seeking planning permission or a contractor undertaking the works, parties should be aware of the risks. This means a thorough desktop survey at the planning stage and where necessary, the appointment of specialist contractors. Contractors assuming responsibility for ground conditions will need to give thorough consideration to any agreed scheme dealing with unexpected finds and factor contingencies into the programme.