Tag Archives: NPPF

Managing Archaeological Risk

Cost of change against project stage (after ICE 1996)

With profit margins becoming increasingly tight in the construction industry, developers are keen to manage and control risk and uncertainty, whether this be related to the cost and availability of materials, ground contamination, or archaeology. As a site’s archaeological potential is usually unknown, it is a case of moving the site from the unknown, to the known. It will usually be a staged process that is necessary, with each stage of work reducing the level of uncertainty, and therefore the level of risk. The earlier it is considered in a development program the better, as it allows more time to work out projected costs and incorporate any necessary changes to reduce these costs, into a design programme.

Example of Historic Environment Record data

For many projects, most commonly the first step is a desk-based assessment, a non-intrusive survey of known evidence using a range of sources such as historic maps, aerial photos, and the Historic Environment Record, the local authority’s database of sites and findspots. This will determine the likely archaeological potential for a site and is a relatively rapid and cost effective technique. This may not be necessary for small projects however – such as extensions, or one or two dwellings, but developers can seek advice from the local authority archaeologist on this at an early stage.

Deposit model prepared to consider likely depths of archaeological deposits

More and more often however, as a result of NPPF, planners are asking for much more site specific information concerning the likely impact of a development. In these instances the document required is variously called a heritage statement or heritage impact assessment, where a consideration has to be made of the precise nature and extent of the likely impacts of the development upon the identified archaeological resource, as well as putting forward proposals as to how to mitigate the effects of the development upon this archaeology. This relates to both the physical impacts on the below ground archaeology as well as on the setting of monuments in the wider landscape. The issue of setting is a much wider topic, particularly with relevance to wind turbines, which are visible for many miles.

Gathering such information at an early stage in the design programme, through minimal and often non intrusive archaeological intervention can save the time and costs of either redesigning a development plan to avoid the need for further archaeological works, or archaeological excavations further down the line causing added costs and delays. Another thing to consider is engaging an archaeologist to monitor any geotechnical works that are being undertaken, as this will give a good indication of the likely depths of archaeology, made ground or truncation across a site.

More often than not, a DBA may identify an archaeological potential for a site but cannot within certainty determine the precise nature of the archaeological resource that may be present, in which case, intrusive works may be necessary to further characterise the archaeology present within the site – usually, where ground conditions are appropriate, geophysics is a common starting point, followed by trial trenching. As well as providing information on the below ground archaeology, geophysics can help inform and also limit the extent and therefore cost of subsequent targeted trenching.

Evaluation trenching strategy based on geophysical survey results

This level of work should provide a planning authority with sufficient information upon the archaeological resource to allow for the determination of a planning application, and to establish appropriate measures, known as final mitigation, undertaken as a condition of planning. It may be the case that the trial trenching finds little or nothing of interest and that no archaeological condition is imposed. However, where this is not the case, developers will need to consider measures to either preserve the archaeological remains in situ, or to preserve by record, ie. dig it all up.

The concept of preserving the remains in the ground wherever possible, ie preservation in situ, is one of the prime considerations for archaeology and is considered preferable to excavation, ie preservation by record, as this is in itself a physically destructive process. Obviously it also reduces the developer’s bill for archaeology, and in purely financial terms, there is a consideration on such sites as to whether it would be cheaper to use a potentially more costly foundation design (eg piling) that preserves the archaeology, or fund an excavation that records the archaeology to the satisfaction of the planning authority, but allows a more cost effective foundation design to be used. Redesign of the development layout should also be considered, for example, relocating areas of public open space to protect areas of archaeological interest.

So there are ways to manage the archaeological risk, and the thing that we always try to stress to developers is to build in time to consider the likely archaeological issues that may affect a site. Most county councils employ archaeological officers whose role it is to advise planning officers and developers upon the likely implications of a development, and most archaeological contracting companies will also be happy to advise a client. It is sometimes possible to come up with ways to avoid or greatly reduce the need for archaeological investigations, and it is usually possible to manage the risks associated with the possibility of unforeseen costs or delays caused by unexpected findings. Archaeology is inherently unpredictable however, and we never know for certain what we are going to find. I am afraid that we as archaeologists can’t be held responsible for what the Romans did 2,000 years ago!

Heritage Research: engaging with landscape architects

At the beginning of the week the heritage team (Chris, Catriona and myself) met with the landscape architects at Influence®. We were interested in discussing the similarities and differences between their landscape and visual impact assessments and our own approaches to studying the impact on the setting and significance of heritage assets (discussed in this blog).

Landscape and visual impact assessment is often required as part of a planning application and helps to assess the effects of future development on the landscape. A report will help to inform design, in order to reduce and offset some of the adverse effects of development on the surrounding area. It will consider the existing character of the place, and potential changes to the available views. A study of the landscape can be applied to all urban and peri-urban landscapes, towns, villages and rural areas, coast and islands area; and the views can encompass a wide range of features including National Parks, Areas of Outstanding Natural Beauty, Nature Reserves, Listed Buildings, Scheduled Monuments, etc. Of course there is large overlap in the subject matter, although the principle difference between the approaches in that landscape and visual impact assessments attempt to establish and protect the landscape and views as experienced by current individuals. Our research seeks principally to outline the impact of development on understanding the past context of heritage assets and negate factors that might detract from how we comprehend the past, in essence to assess the likelihood for encountering subsurface archaeology and how developments will affect standing heritage assets.

Getting a chance to discuss the similarities and differences between our approaches helped us to appreciate the complexities of each other’s disciplines. We ended up being able to reflect on our own practices and in the future will be incorporating features from their approach to landscape and visual impact assessment into our own study of the impact future development of the setting and significance of heritage assets. It was a great opportunity and are very grateful to the staff at Influence in Newark for hosting us.

Heritage Research: What is the Desk-based Assessment

The initial stages of archaeological work can often be complex and differs greatly between sites depending on the individual peculiarities of the project. Often the first stage of work falls to the Heritage Research Department at AAL, consisting of Josh, Catriona and Jesse, and the writing of Desk-Based Assessments (DBAs).

Aerial photograph showing cropmakrs comprising circular enclosures

A DBA attempts to assess whether there is likely to be any archaeological remains on or near a planned development, and whether the development will affect the setting or significance of known (and usually designated) heritage assets, such as listed buildings. The DBA is in essence a short research project exploring all the aspects of the history and archaeology of a particular piece of land. These can be buildings due for renovation or demolition, planned housing schemes, solar farms, cable lines and a whole variety of other reasons.

The starting point for a report is usually the local Historic Environment Record (HER); previously known as Sites and Monuments Records (SMRs). They are databases of information relating to the historic environment and contain information about archaeological works, buildings, landscapes, finds and a whole range of other things associated with the human past. You can access a lot of the information from Heritage Gateway if you are undertaking personal research.

The results of a HER search will tell us what known archaeological and heritage assets are located within defined area. However, this record is not everything. A report can also include sifting through the local archives for historical documents; indicating land use of the site over time, or investigating cropmarks shown on aerial photographs, and analysing maps of the past for evidence of shrunken villages. Some sites require a closer understanding of the underlying geology to predict whether prehistoric activity is likely, and others need to check whether 20th century buildings are likely to have truncated the archaeological resource.

Ridge and Furrow spotted on a site visit

Yet, part of the job also involves getting out the office and into the field (as we are still archaeologists!). Our site visits might include visiting ancient monuments, exploring parks and gardens, inspecting and recording old buildings, and visually assessing seemingly innocuous land, searching for potential clues of archaeological remains that might lie beneath. Without visiting the site it can be impossible to know how it relates to the landscape surrounding it.

A DBA is often undertaken at the pre-planning stage in order to highlight the potential for archaeological remains in advance of construction taking place. This allows the developer to prevent damage to the archaeological resource and the associated costs of excavation by changing the specifics of the development. For instance, the developer might choose to leave open spaces for recreation on houses estates over areas of known archaeological interest in order to avoid disturbing underlying remains. You never know, your local park might be on the ground of a Roman villa or a medieval castle! In addition, DBAs allow the local planning authorities to make decisions about whether or not excavation is required for planning permission, in cases where it is not practical to change the nature of the development. That’s when archaeologists get their hands dirty!

Preparing DBAs can be really rewarding projects for people who want to expand their knowledge of British Archaeology. You have to know a little bit about everything, and know where to start looking for more information and when to spend more time exploring something.

Archaeology in the commercial world

The discipline of archaeology is as old, or older than some of the finds we dig up every day, with the first documented archaeological dig dating to the 6th century BC when the Babylonian king Nabonidus led excavations to find the earliest phases of several palaces and temples in ancient Babylon.

Roman colonnade discovered in Lincoln in 1878

In recent history, the discipline of archaeology began as a gentlemanly pursuit, with the profession gradually developing an increasingly scientific approach thanks to a number of scholars in Europe and America during the 19th century, such as General Pitt Rivers; a British soldier and adventurer, who brought military precision and organisation to the process of archaeology. Nevertheless many archaeological discoveries were still chance finds during development. In the 20th century, another military man, Mortimer Wheeler, also employed military precision in his numerous excavations in Britain and India, and helped bring archaeology to a mass audience through numerous TV and radio appearances.

General Augustus Pitt-Rivers 1827-1900

As the pace of development increased in the post-war years, the relationship between archaeology and development changed. It became apparent that many important archaeological sites were being lost, with little or no record. This led to the evolution of a whole new discipline of ‘rescue archaeology’ or ‘salvage archaeology’, which introduced new techniques to maximise the recovery of archaeological data with the limited time and resources available. This led to the development of a number of archaeological organisations, often based within and partially funded by local authorities, as well as by developers, to undertake these rescue digs.

Legislation was slow to catch up however, and it was not until, in 1990, with the implementation of PPG 16, the ‘polluter pays’ principle was applied to archaeology and development. This piece of planning guidance placed a burden upon the developer to ensure that archaeological remains at threat from development were adequately recorded, with that funding coming directly from the developer, and the work more often than not being secured by planning conditions. In some local authorities there was a feeling that more work should be undertaken pre-determination, both to limit future delays to construction programmes, and due to the concern that should important remains be exposed, there was little chance to offer them legal protection or record them adequately once a grant of planning permission had been issued. This finally manifested itself with the release of PPS5 in 2010, which placed greater emphasis on providing more information on a sites archaeological potential prior to submission of a planning application. PPS5 was short lived, but much of the guidance in PPS5 was adopted into the new National Planning Policy Framework in 2012.

The provision of developer funding for archaeology resulted in the development of numerous independent archaeological companies, and in recent years, the local authority based units have largely died out. Most companies nowadays are small, with tens of employees rather than hundreds, as well as numerous sole traders, particularly in the fields of specialist finds analysis. The fact that archaeology is developer funded also means that it is subject to competitive tendering to win projects, with the best price to fulfil the councils brief for the works usually being the winner. As such the whole process is very different to the preconceived notion of a cohort of academics and university students spending season after season studying every aspect of a single site in painstaking and minute detail. Furthermore, we can no longer choose where to go and what to dig up, rather, we are driven by the needs of our clients, so one week we may be excavating an Anglo-Saxon cemetery in Norfolk, then the next week Victorian tenements in Sunderland. Unfortunately, this also means we cannot, like academic research digs, restrict our digging to a few months in the summer, but have to be outdoors all year round, so a decent set of waterproofs and some woolly socks are a must!!

Hoeing snow at Sleaford Power Station

Because of the restrictions imposed by the nature of the industry, commercial archaeology can often seem a brutal process, with a lot of the heavy work undertaken by mechanical excavators, or a ‘big yellow trowel’ as they are colloquially known. That’s not to say there is not a lot of manual work after that. As soon as the topsoil is stripped off a site, its down to the mattocks, spades and shovels, and yes the trowels do still make an appearance as well. An experienced archaeologist can move a remarkable amount of soil with a trowel, and they have also been known to come in handy for cutting birthday cake in an emergency!!

In the 21st century, development led archaeology represents by far the majority of archaeological work undertaken in the UK, and the fact that this archaeological work is driven by the location of new developments, rather than a research focussed programme intended to test or prove a certain theory, has resulted in a new understanding of the country’s history and heritage, often leading to reappraisal and revision of traditional theories. The vast majority of the output of commercial archaeology is in the form of reports required by the planning authority, ‘grey literature’ as it is known, with only a minority of key sites reaching formal publication. However, numerous attempts have been made by academic researchers and commercial archaeologists alike in recent years to collate and interpret this ever growing body of data to further the understanding of the finite archaeological resource that lies beneath our feet.