4. Understanding Impacts and Opportunities (HIA)

When the proposed peatland restoration plans have been determined and agreed by all parties, the impact of the proposal on the significance of the historic environment (as identified in the desk- and field-based surveys), including its setting (see Historic England 2017b), will need to be set out in a HIA – just as with an EIA.

Like the previous stages, this work should be done by an appropriately qualified archaeological specialist, and in accordance with recognised standards, for example CIfA/Institute of Building Conservation (IHBC)/Institute of Environmental Management and Assessment (IEMA)’s Principles of Cultural Heritage Impact Assessment in the UK (IEMA 2021) or Historic England’s Statements of Heritage Significance: Analysing Significance in Heritage Assets Historic England Advice Note 12 (Historic England 2019).

For projects in World Heritage Sites, production of the HIA will also need to follow United Nations Educational, Scientific and Cultural Organisation (UNESCO) guidance (see UNESCO et al 2022).

The impact assessment should review the evidence collected during the resource assessment stages (desk-based study, field-based investigation and archaeological evaluation, hydrogeological assessment, and peat preservation).

The HIA should demonstrate the appropriateness and utility of the proposed work(s) for the site, and, where appropriate, identify opportunities to improve the management of historic environment features within the site area, maximising both nature conservation and heritage priorities. The impact assessment should cover:

  • the restoration site(s)
  • locations where the restoration materials are being stored
  • access routes
  • any areas in the vicinity from which restoration material (e.g. heather brash) is being sourced
  • the duration of any works

Effort should be made to present the results of an HIA in a way that is accessible to non-archaeologists, such as peatland contractors, and that will integrate into a peatland funding proposal. Tables or colour-coded maps (see Thom et al 2019, 60), for example, can be used to identify and distinguish areas of differing archaeological importance as well as no-go areas during restoration works (Figure 11).

Key questions to address in the HIA could include:

  • How will the proposed scheme and methods impact the site’s groundwater function and status (e.g. water levels and chemistry)?
  • What will the impact be of proposed site changes on the preservation, integrity, significance and setting of: i) above-ground historic environment features, and ii) below-ground archaeological and palaeoenvironmental remains?
  • What short and long term changes will there be to the historic landscape character?
  • What commonalities are there with the restoration conservation objectives? How will the work reach a compromise between potential conflicts?

If a HIA indicates that current proposals are harmful to peatland heritage, those producing the HIA will need to discuss any adjustments to the restoration work with the project team, and with input and advice from the local authority archaeologist (curator).

They might want to consider the balance between the harm to the significance of the heritage assets and the benefits provided by the peatland restoration and ensure that any modifications to the proposed restoration plans will still result in improved peatland condition. This stage may be iterative.

The final scheme should result in positive outcomes for the historic environment elements of the peatland, wherever feasible, this may include:

  • enhancing the long-term survival of peatland heritage features, for example, through improving the groundwater conditions and minimising erosion
  • avoiding physical and chemical impacts to known historic environment features and their setting or areas of high archaeological potential
  • minimising intrusive work in areas of significance, and using peatland restoration methods that respect and enhance the existing historic landscape character
  • mitigating when works to known peatland heritage are inevitable. In situations where certain aspects of peatland restoration result in unavoidable impacts to the historic environment, this harm to significance needs to be mitigated by work to investigate, record, and analyse those features and deposits which are lost

KEY POINTS:

Heritage impact assessment (HIA) will draw together all information about the proposed restoration scheme and available heritage data to the impact of the proposal on the setting and significance of the historic environment. Where historic environment features are present in a peatland restoration site, the approach to these needs to be considered in this order:

ENHANCE > AVOID > MINIMISE > MITIGATE

It is not automatically the case that peat proposal areas that include heritage assets must be excluded from restoration works; it will depend on factors including: the restoration techniques to be used, if positive outcomes for certain heritage assets will result, and/or whether any of the heritage features themselves are detrimental to the site’s peat function and condition (in which case excavation and recording might be a valid approach).