Spotlight: Impact of archaelogical work

If your proposed construction project is in a historic town or city there is a possibility that you will be required to make provision in your programme for archaeological works. Major developers and contractors in the UK’s historic cities are used to making provisions for this, but for others the mere mention of archaeology strikes fear because of the potential impact on their construction programme. Generally it is the uncertainty of the unknown that creates this fear, perpetuated by rumour and conjecture. This article puts the spotlight on the principles of managing the impact of an archaeological dig on your project to minimise uncertainty and the impact on lead times.

A developer has an obligation to make allowance in the preparation of a planning application to assess the likelihood of there being archaeology on a site. Should the site have any hint of archaeological interest, the developer is required to make an assessment of the impacts and any possible mitigation measures.

As well as being a planning obligation, it makes good sense to understand and manage this element. This process may, and often does, influence the design in terms of foundation types and depth if the likelihood of finding archaeology is high. The biggest risk is to ignore this stage as it will mean that provision will not be made in the work. If archaeology is discovered later, the impact on the programme is likely to be greater, with potential for abortive work or delays.

An archaeological assessment is attached as part of the environmental impact assessment prepared for all major planning applications. This usually requires the employment of an archaeological organisation such as Museum of London Archaeology (MOLA) to prepare a desktop study describing the history of the site and looking at areas of particular interest. It will also assess where previous buildings on the site may have already reduced the risk of finds. The findings of this report are usually fed into the project risk schedule, but are a distinct chapter within the environmental impact assessment for any major project.

If time and existing site ownership and leasing arrangements allow, trial pits are excavated to confirm or otherwise the likelihood of there being any artefacts where the desktop study suggests they may exist. At this stage, the archaeologists would give an estimate of programme and cost, and assess where a “watching brief” may be required to mitigate the possibility of further finds during the project works.

The planning application is submitted, which includes the updated archaeology desktop study and outlines any mitigation strategies such as redesigned foundations. On receipt of planning approval, the development team (through the archaeologist) is obliged to agree a method statement and programme for archaeology on the site with the local authority’s archaeology officer. This strategy must be agreed before any works likely to disturb the archaeology commence. A planning condition is likely to be inserted into the planning consent.

Further trial pits may be carried out to mitigate risk at this stage. The demolition package will be let to include any necessary programme allowances and attendance required by the archaeologists. The substructure contract must also be let on the same basis.

The timescales for when the archaeologists will be required on site are set out in the pre-start method statement and the timings are given to those tendering for affected works. The developer usually pays their direct costs for archaeological assessments and buys attendances through the main contractor and its subcontractors.

However, the archaeologist is required to liaise with the local authority and to advise it should any further or more extensive finds be made. If this occurs, the developer and main contractors are obliged to incorporate whatever additional time is required at the cost of the employer.

Often developers will make archaeology found on their sites public and share news of finds with the community as part of their communications plans. They may in some cases also be asked to fund and participate in exhibitions. All finds made on the development become public property.

In summary, archaeological works should be seen the same as any other aspect of construction work. The work should be properly assessed and planned by qualified archaeological consultants at an early stage as they will be able to plan and coordinate the works to minimise the impact on programme.