Generic brief for an archaeological evaluation (trial trenching)

Accurate and precise surveying is essential. Trenches should be set out using GNSS or TST survey equipment. Trench locations should be tied in to the Ordnance Survey (OS) National Grid and Ordnance Datum (OD) (Newlyn).
Coordinates relative to both the OS and OD should be obtained for all sampling locations, small finds and any other relevant deposits or features.

Trial trenches are normally a minimum of c 1.8m wide, although wider trenches or "boxes" are sometimes more appropriate.

Machinery may be used to remove topsoil and overburden to reveal the archaeological deposits.

Such excavation should be undertaken in level spits using an appropriate machine using a toothless bucket and working under archaeological supervision.

Archaeological deposits should not be removed by machine except where such a procedure has been sanctioned by the Council Archaeology Service.

Particular care should be taken when controlling machining in situations where vertical stratigraphy is to be expected or where it is considered that significant archaeological deposits may be vulnerable to damage - in such circumstances machining should be controlled by experienced senior staff. Potentially significant deposits should not be removed by machine before their character is reasonably understood.

Each trench should be cleaned by hand sufficiently to allow the identification and planning of archaeological features and scanned with a metal-detector.

Spoil heaps should also be scanned. Experienced metal-detectorists should be used but only on the understanding that they work to the direction of the archaeological contractor and that the ownership of all finds remains with the landowner.

Where archaeological features appear to be absent sufficient work should be done to demonstrate this. Each trench should be planned at an appropriate scale (normally 1:20 where complex deposits are present or 1:50 or 1:100 in areas of lesser complexity). Spot levels should be taken as appropriate.

Sufficient features should be sampled by hand excavation to achieve the project objectives.

For discrete features such as pits and postholes this will normally involve half-sectioning a representative sample. Linear features should be sectioned. Individual complex features such as kilns or burials should be cleaned and recorded but, subject to the agreement of the Council Archaeology Service, it will normally be preferable to leave them in-situ (if necessary with specific protection against disturbance during backfilling).

If deeply stratified deposits are encountered it may be appropriate to excavate sample boxes and/or examine the stratigraphy revealed in the section of excavated cut features.

Each context should be recorded on pro-forma records which should include the following minimum details: character; contextual relationships; detailed description (dimensions and shape; soil components, colour, texture and consistency); associated finds; interpretation and phasing as well as cross-references to the drawn, photographic and finds registers. Normally each context should be recorded on an individual record. Sections should be drawn through all significant cut features and levelled to ordnance datum. Representative trench sides should also be drawn in section and where they contain significant information.

A digital photographic record should be maintained including photos of all significant features and overall photos of each area or trench. Selected black and white and/or colour transparencies should also be taken.

If contractor specific digital recording is proposed, this must be clearly described and a copy of the Digital Management Plan should be referred to.

All stratified finds should be collected by context or, where appropriate, surveyed to provide co-ordinates relative to both the OS and OD. Unstratified finds should only be collected where they contribute significantly to the project objectives or are of particular intrinsic interest. Provision should be made for on-site conservation advice for the lifting and treatment of fragile objects. If fragile items of particular significance are discovered, a conservation management plan will be produced by the contractor at the earliest opportunity in consultation with the curator, museum team and any external specialists. Regular updates on the preservation of the item will be given to the Council Archaeology Service. Finds of "treasure" must be reported to the Coroner in accordance with the Treasure Act procedures.

Collection policies for structural remains and industrial residues have been set out by the Society of Museum Archaeologists (SMA, 1993). The presence of such materials within a context should always be recorded and, where they are considered to be of importance, the evaluation strategy should aim to quantify their occurrence, even where comprehensive retention is not considered appropriate.

Contractors should, where relevant, follow the guidelines for handling Post-Roman Ceramics produced by the Medieval Pottery Research Group (Slowikowski, Nenk & Pearce, 2001). This specifies that all ceramic finds must be collected, washed, marked, bagged, boxed and assessed with regard to the project aims and objectives. Where a sampling procedure is employed this should be undertaken in consultation with a ceramic specialist.

Contractors should refer to Environmental Archaeology: A guide to the theory and practice of methods from sampling and recovery to post excavation (English Heritage, 2011) as a guide to best practice in this field.

Waterlogged wood should be treated accordance with English Heritage guidelines (English Heritage, 2010) and left in-situ where this is practical and its long-term preservation is achievable.

A contingency for scientific dates should be allowed if pre-Iron Age remains are potentially present.

In the event of discovery of any human remains the archaeological contractor should inform the client, the Council Archaeology Service, and the Ministry of Justice via the submission of an application form for the ‘Archaeological/Accidental/Site Investigation Licence regarding the disturbance of human remains’. The Human remains should be left in-situ, covered and protected. Where a licence for their excavation is issued by the Ministry of Justice, the requirements of that licence must be followed. The only exception is where excavations are being undertaken in a churchyard under a faculty issued by the Chancellor of Oxford Diocese (in such cases the faculty requirements should be followed). In certain situations special arrangements may be required for the recovery of samples for DNA analysis. Human remains should be treated in accordance with CIfA guidelines (CIfA, 2004) and the advice set out in Guidance for best practice for treatment of human remains excavated from Christian burial grounds in England (English Heritage, 2005).

An initial assessment of the site's palaeo-environmental potential should be made by the project manager in consultation with the Council Archaeology Service. Where a site may have significant potential it may be necessary to obtain specialist advice and undertake sampling in accordance with a programme agreed with Historic England's Adviser in Archaeological Science. A contingency should be allowed for this.

Whenever private individuals or subcontractors are engaged to undertake metal detecting as part of an archaeological fieldwork project they should be asked to sign a formal agreement in which the right to claim Treasure is waived. Please refer to the third revision of the Treasure Act Code of Practice (2023, Section D, paragraphs 13-16). A suggested clause is:

“In the process of working on the archaeological/ excavation at [location of site] between the dates of [insert dates], [name of person contributing to the project] has been working under the direction or permission of [name of archaeological organisation or responsible individual archaeologist] and hereby waives all rights to rewards for objects discovered that could be otherwise payable under the Treasure Act 1996.

Contracts should ensure that investigations are covered by a written agreement with the owner & occupier regarding rewards which may be payable.

BCAS expect all WSIs to include a commitment to outreach, and for all contractors and consultants to aim to share the findings of their work wherever possible

Some suggested approaches are outlined below:

• a site Open Day
• a targeted invite to a local archaeology society for a site tour or talk to a local group or museum. Society details can be found in the Contacts Section;
• a visit to a local primary school to share findings as part of the KS2 National Curriculum offerings on history National Curriculum - History key stages 1 to 2 (publishing.service.gov.uk).
• a blog post for our council archaeology blog post Heritage and Archaeology | Buckinghamshire Council
• social media updates
• a leaflet drop to nearby residents with a summary overview of what you are doing, why, and a brief description of what’s been found to date
• Participation in a wider event, such as the Festival of Archaeology or Bucks Open Weekend Festival of Archaeology Council for British Archaeology (archaeologyuk.org) Bucks Open Weekend - Visit Buckinghamshire
• Short term loan of appropriate items to the Discover Bucks Museum to tie in with any press releases