A Written Scheme of Investigation, usually shortened to WSI, is the document that sets out how archaeological work will be carried out on a site. It is commonly prepared once planning permission has been granted with archaeology conditions, or when a defined programme of archaeological work needs to be agreed in advance. In simple terms, it is the method statement that explains what will happen, why it is needed and how the work will meet the planning requirement.
Why a WSI is so important in planning
The WSI turns a broad condition or requirement into a practical and agreed programme of archaeological work.
- It explains the scope, aims and methodology of the investigation in a way that the local authority can review and approve.
- It gives the developer and contractor a clear framework for what archaeology work is required on site.
- It helps ensure that fieldwork is proportionate to the planning condition and carried out to an appropriate professional standard.
- Without an approved WSI, later archaeological work can become uncertain, delayed or open to dispute.
What a typical WSI includes
Although the exact content depends on the site and the type of fieldwork, the document usually covers a defined set of practical topics.
- A description of the site, the development proposal and the archaeological background relevant to the required work.
- The objectives, field methods and reporting procedures for the investigation, whether that is a watching brief, evaluation or excavation.
- Arrangements for finds, samples, recording, health and safety, staffing and archive deposition where relevant.
- A clear explanation of deliverables so the authority understands how the condition will ultimately be discharged.
Why the right WSI helps the whole project
A well-prepared WSI is not just for archaeologists. It helps everyone involved understand the sequence and expectations before site activity begins.
- It allows archaeology work to be coordinated more effectively with enabling works, access arrangements and contractor programmes.
- It reduces the risk of confusion about the scale of investigation required or the circumstances under which work may need to pause.
- It supports cleaner communication between the client, consultant, contractor and planning authority.
- It gives the project a realistic archaeology roadmap instead of leaving important questions unresolved until the last minute.
Frequently asked questions
Is a WSI only needed after planning permission?
Most commonly it is linked to planning conditions, but it can also be required in other contexts where archaeological methodology needs formal agreement.
Who approves the WSI?
Usually the local planning authority or its archaeological adviser reviews and approves it as part of the condition discharge process.
Does the WSI include the final results?
No. It sets out how the work will be done. The results are usually reported afterwards in a separate fieldwork report.
Need advice on this type of project?
AS Archaeology & Heritage Services prepares Written Schemes of Investigation that turn archaeology conditions into clear, workable site programmes aligned with the development timetable.
Related links: Written Scheme of Investigation | Archaeological Fieldwork | Contact AS Archaeology