The Planning Process - Principle Stages
The Principle Stages for handling archaeology in the planning process, in line with the Government's Planning Policy Guidance notes PPG15 and PPG16, are:
(requirements are set out in more detail in the GLAAS Guidance Papers)
Pre-Determination:
- Desk-based assessment
- Field Assessment
Post-Determination:
- Preservation in situ
- Preservation by record (excavation)
Archaeological remains are irreplaceable, a finite, and non-renewable resource. They are part of our sense of national identity and are valuable both for their own sake and for their role in education, leisure and tourism.
There should be a presumption in favour of the physical preservation of nationally important remains, whether scheduled or not, and their settings. For remains of lesser importance a planning decision must weigh their value against other factors. If archaeological remains cannot be preserved, a record of them should be secured before construction works that would destroy them commence.
The key to a successful planning application and good planning decisions is having adequate information from the start. Pre-application, or pre-land purchase, consultations are therefore encouraged. There are, typically, two stages to data gathering, firstly a desk-based assessment, and secondly field evaluation, that may be required prior to the determination of outline or detailed planning applications.
Archaeology and development. A good practice guide to managing risk and maximising benefit Barber B, Carver, J, Hinton, P, Nixon, T, CIRIA 2008 is a useful reference work.
Pre-Determination
- A desk-based assessment is an assessment of the known or potential archaeological resource within a specified area or site, consisting of a collation of existing written and graphic information in order to identify the likely character, extent, quality and worth of the known or potential archaeological resource in a local, regional or national context as appropriate.
A field assessment (evaluation) is a limited programme of non-intrusive and/or intrusive fieldwork aimed at gaining information about the archaeological resource within a given area or site. This includes the presence or absence, character and extent, date, integrity, state of preservation and relative quality of archaeological remains and may involve a variety of investigative techniques, including fieldwalking, trial trenching and geophysical survey. It enables an assessment of the worth of any archaeological remains in a local, regional, national or international context and provides the basis for recommendation of appropriate mitigation strategy. This may comprise full or partial preservation in situ, further investigation and recording, or the results may merit no further archaeological work.
Building recording is a programme of work intended to establish the character, history, dating, form and archaeological development of a specified building or structure, or complex and its setting, including its buried components. It aims to both seek a better understanding of the structures and enable formulation of a strategy for their conservation, alteration, demolition, repair or management. For more information please see Understanding Historic Buildings: A guide to good recording practice - Part 1.
Where a desk-based assessment raises the possibility that archaeological remains may survive on a site, but cannot in itself define them, further field evaluation will be needed. On the other hand a desk-based assessment may demonstrate that the land has been subject to previous ground disturbance that would already have removed any archaeological remains. Desk-based assessments can help target any subsequent evaluation, to maximise the results of selective work.
Field evaluation will usually involve some form of ground intrusion, although fieldwalking of ploughed fields, and remote sensing, may cause no ground disturbance, other techniques such as test-pitting, trial-trenching, or borehole survey will be intrusive. Some of these may be cost-effectively combined with soil engineers’ investigations. Different techniques will be appropriate to different site conditions and the anticipated archaeology. Access to some sites, particularly in the urban context, for such investigations may be difficult to achieve.
Building recording and analysis may be necessary, both pre-determination to understand a structure, and post-determination to record alterations to it. For larger or more complex sites a Conservation Plan should be prepared, that might combine the results of desk-based assessment, building recording and any previous archaeological investigation. This would define parameters for alterations and site improvements within which informed planning applications can be made.
Determination Considerations
Once the information from the desk-based assessment and field evaluation has been gathered the importance of any archaeology can be assessed. If it meets the criteria for national importance (set out in PPG 16), we would recommend that the Local Planning Authority (LPA) should seek proposals to redevelop the site that ensure preservation of the remains. This may involve a sympathetic foundation design, raising floor levels, possibly displaying the remains, and monitoring the site for changing ground conditions. If such preservation cannot be achieved we would recommend refusal of the planning application.
More typically, we would advise the excavation and recording of archaeological remains, in a programme of work that included analysis and publication of the results. We would seek the communication of these results to the public, and the ultimate deposition of the archive where it can be examined and studied in the future. We would secure such an investigation through planning conditions attached to planning consents issued by the LPA, modelled on that recommended in PPG16, para. 30.
Where pre-determination field evaluation cannot be achieved, conditions may be imposed to secure both field evaluation and subsequent excavation. The final foundation design may also be reserved so that if significant remains come to light, they may be preserved in situ, where possible.
Post-Determination
Preservation in situ:
foundation design to avoid or minimise impact on archaeology may be sought. This might include locating buildings to avoid archaeology; display of remains; sympathetic location of piled foundations and piling techniques; raising floor or ground beam levels; the routing of services; management of ground water. Landscaping and planting may also be constrained.monitoring over a number of years after completion may be needed to assess if the preservation techniques have been successful.
Preservation by record:
excavation is the excavation and recording of archaeological evidence which will be unavoidably destroyed by development. Its purpose is to examine the archaeological resource within a given area or site within the framework of defined research objectives, to seek a better understanding of and compile a record of that resource, and disseminate it.
a watching brief is a programme of observation and investigation conducted during any operation carried out for non-archaeological reasons where there is a possibility that archaeological deposits may be disturbed or destroyed, enabling recording of archaeological evidence which comes to light during the course of development.
When an archaeological investigation has been secured by planning condition, the applicant (or their agent) is expected to submit a Written Scheme of Investigation (WSI) to the Planning Department for their approval before the investigation can commence. This is typically prepared by the archaeological practice appointed by the applicant, to a brief from the GLAAS Advisor. A range of approaches may be employed. Full-scale excavation may be required, this is sometimes implemented in a phased manner, handing over parts of the site at set intervals so that construction can commence in tandem with the archaeological excavation. Some investigations are targeted on certain parts of a site, or may consist solely of geo-archaeological boreholes to characterise the sedimentary sequence.
The Written Scheme of Investigation should be in accordance with GLAAS guidance papers – in particular to ensure consistency of the archaeological record for comparative purposes across London. It should set out the research questions being asked of the site at the outset of the project, and should make commitment to a post-excavation assessment of the finds made, their analysis and publication/dissemination, as well as the long-term deposition of the site archive. Until all these stages have been achieved the planning condition that has secured the WSI will not have been fully complied with. We would also expect to see proposals for the popular communication of the investigation and/or its results, particularly to the local community.
If an evaluation is being undertaken post-determination, a two stage process is necessary, whereby the results of the evaluation are submitted to the LPA, and if further excavation is merited a second WSI submitted to them to cover this. Construction cannot, usually, start until this second phase has been completed.
In some cases a watching brief during groundworks is merited, to record archaeological remains if they are exposed, this may be on smaller sites, or where pre-construction access cannot be achieved. This carries the risk that building works may be delayed if significant archaeology comes to light.
The GLAAS advise the applicants and their agents to guide them through archaeological issues in the planning process. We would monitor works on behalf of the local authority to ensure the necessary requirements are being complied with, and track the post-excavation process.
Building recording may initially be undertaken pre-determination to fully understand a structure on which to base planning decisions. Further recording may be necessary as parts of the structure are exposed during alterations, and to record elements that are to be removed or demolished. Some buildings that are not protected through Listing or in a Conservation Area, may nervertheless merit record, for the contribution they have made to the past town or landscape and social history, prior to alteration or demolition. In particular in the case of industrial buildings, they may have had an important role in the local economy or in the history of technological innovation. It is important in these cases to record evidence for the industrial activities that took place within them, usually prior to internal stripping out.
These brief notes are intended as an introduction to archaeological procedures in the planning system and how they are applied in London. If you have more detailed questions please do not hesitate to contact one of our advisors. You may find further information through the weblinks to key archaeological websites, or the HELM website – which provides a broad suite of advice papers on all aspects of the management of the historic environment.
(Last Updated: 8th Dec. 2008 Robert Whytehead)
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