What is a Written Scheme of Investigation (WSI)?

As mentioned in our earlier blog, archaeological fieldwork is sometimes required as part of the planning process – either before a decision is made (predetermination) or as a condition of planning approval. This work helps gather valuable information about the historic environment, which is then used to inform the local planning authority (LPA).

Before any fieldwork can begin, a document must be prepared that outlines what will be done (the scope) and how it will be carried out (the method). This document is known as a Written Scheme of Investigation (WSI), and it’s a key requirement before any archaeological work can take place on site.

What does a WSI include?

A WSI is typically prepared by the archaeologist supporting the planning process. It is something consultants in Savills Heritage and Townscape team produce on behalf of clients as part of our role in both helping them navigate the ways in which archaeology may affect their proposals, as well as coordinating relevant research and fieldwork.  

The WSI sets out the purpose and aims of the investigation, along with the scope of works. It explains why the investigation is needed and what type of fieldwork will take place – such as a geophysical survey, trial trenching, or other methods. It also defines the standards under which the fieldwork should be carried out, and includes health and safety considerations. 

In addition, the WSI outlines the next steps following the completion of the works. These usually include assessing the archaeological results, producing a report, and archiving both the records and any artefacts.

Typically a WSI is comprised of two parts. The first, the main body of the WSI, sets out the information described above which essentially details what archaeological fieldwork needs to take place. The second part, known as the Method Statement, is produced by the archaeological fieldwork subcontractor appointed to undertake the work. This is included as an appendix to the main body of the WSI and sets out how they will undertake the required scope of archaeological fieldwork. It will include information such as responsible staff, the specialists to be used (for each of the different types of artefacts), what equipment will be needed, the excavation and recording processes, and health and safety procedures.

Once the Method Statement is appended to the WSI, the complete document is submitted to the county archaeologist at the relevant LPA. Their approval must be given to the content of the combined document before the on-site archaeological fieldwork investigations can begin. 

Further information

Contact Konstantinos Bompotis or Dr Rachel Scrutton