What a Written Scheme of Investigation Actually Is

What it is for

A WSI is a method statement for archaeological work, submitted for approval by the local planning authority before that work begins. It exists because an archaeological condition cannot sensibly specify method in its own wording: the authority approves the approach separately, once the site is understood.

Because it is approved, it becomes the benchmark. If fieldwork departs from it, the departure has to be agreed. If the report does not deliver what it promised, the condition is not discharged.

What it has to contain

A thin WSI gets rejected, and rejection costs weeks at the point in the programme least able to absorb them. A competent one covers the following as a minimum.

• Site location, the development proposal, and the extent and depth of ground disturbance
• Archaeological and historic background, including HER data and previous fieldwork on or near the site
• Aims and objectives, framed against regional research priorities where the authority expects it
• Method statement: fieldwork technique, sample size, recording standards, finds and environmental sampling strategies
• Programme, staffing structure, supervision arrangements, plant and monitoring points
• Reporting stages and timescales, archive standards, and the receiving repository for deposition
• Health and safety arrangements, and how unexpected discoveries will be handled and instructed

Why it is a commercial document

Everything that drives archaeological cost is decided in the WSI: how much of the site is excavated, how intensively features are sampled, how much specialist analysis is committed to, and how the work is phased against construction. Once approved, those parameters are difficult to reduce.

This is why we prepare the WSI only after the scope has been discussed with the authority's archaeological advisor. Submitting a scheme cold, in the hope that it will be accepted, tends to produce either rejection or an approval you did not want to live with.

Who should write it

The appointed archaeological contractor, normally — because the document commits that contractor to a method, a resource level and a reporting standard. A WSI written by one party and delivered by another is a common source of dispute when fieldwork turns out to be harder than the document assumed.

If you already have an approved WSI and are retendering the fieldwork, send it to us. It tells us more about your likely cost and duration than almost anything else you could provide.