Developments such as the proposed wave farm may have the following impacts:

Transcription

1 18. ARCHAEOLOGY AND CULTURAL HERITAGE 18.1 Introduction This chapter considers the potential impacts of the Lewis Wave Array development upon cultural heritage assets. Cultural heritage assets are here taken to comprise all assets that may be of archaeological or historical interest and adverse impacts considered include both physical damage and impacts upon setting Baseline studies have been prepared for the onshore and offshore elements of the wave array and are presented as appendices (Appendices 18.1 and 18.2 respectively). Assets are referred to by numbers issued in the course of this study, prefixed by A Summary of assessment on cultural heritage resources The assessment has considered potential physical impacts upon assets within the application area and setting impacts upon designated or nationally important assets within 1km of the proposed development site. Baseline studies comprising desk-based assessment and site visits have been completed and the results of these inform the impact assessment The results of the baseline studies have fed into the design of the project and impacts have been avoided as far as reasonably practicable, with the result that just two recorded assets will be impacted upon by the development. These comprise an area of lazybeds (ridges formed to increase the cultivable depth of soil and improve drainage) that will be partially removed during construction and a scheduled monument, the setting of which will be slightly impacted by the development. Previously unrecorded archaeological features may be disturbed during construction, though the potential for this to occur is considered low. Impacts have been assessed as being of minor or lesser significance following the implementation of mitigation Potential impacts Developments such as the proposed wave farm may have the following impacts: Direct physical impacts. These may comprise disturbance or removal of cultural heritage assets during construction, either where assets lie within the construction footprint and are hence unavoidably impacted upon or as secondary impacts, eg. as a result of plant movement or anchoring of construction vessels Indirect physical impacts. Degradation of waterlogged deposits owing to changes in hydrology or changes in coastal processes, resulting in increased erosion leading to loss of deposits/features or increased deposition leading to protection of assets from physical damage, for example Setting impacts. These are most likely to occur directly as a result of visual intrusion resulting in a loss of cultural significance. Indirect setting impacts are highly unlikely to occur as a result of this type of development. Page 1 of 13

2 18.4 Methodology The assessment has proceeded as follows: Baseline data gathering (desk-based assessment, walkover survey and site visits); Identification of potential impacts; and Assessment of impacts. Legislation, Guidelines and Policy Framework The assessment has been undertaken with reference to the following legislation: Marine (Scotland) Act 2010; Protection of Wrecks Act 1973; The Protection of Military Remains Act 1986; Ancient Monuments and Archaeological Areas Act 1979; Merchant Shipping Act 1995; Valetta Convention; ICOMOS; and UNESCO The following guidance has been referred to: Institute for Archaeologists (IfA) guidelines: Standard & Guidance for Archaeological Desk Based Assessment (2011); Historic Scotland Managing Change: Setting (2010) Joint Nautical Archaeology Policy Committee (JNAPC) Code of Practice for Seabed Development (2008); COWRIE Historic Environment Guidance for the Offshore Renewable Energy Sector (2007); COWRIE Guidance for Assessment of Cumulative Impacts on the Historic Environment from Offshore renewable Energy (2008); COWRIE Guidance for Offshore Geotechnical Investigations and Historic Environment Analysis: guidance for the renewable energy sector (January 2011); The Crown Estate (2010). Offshore Renewables Protocol for Archaeological Discoveries; The Crown Estate (2010). Round 3 Offshore Renewables Projects Model Clauses for Archaeological Written Schemes of Investigation; and Page 2 of 13

3 Towards a Strategy for Scotland s Marine Historic Environment (Historic Scotland 2009) Consultation The Scoping Opinion is provided in Appendix 2.1. Table 18.1 outlines the responses relevant to this chapter. Table Issues raised in the scoping opinion (Marine Scotland 2011) Comments & information Historic Scotland identified potential for setting impacts upon scheduled monuments located along the west coast of the island. The Western Isles Council requested that a desk-based assessment and walk-over survey of the application area be undertaken The impact assessment should consider the following and provide appropriate mitigation proposals: Direct physical impacts resulting from construction; Indirect physical impacts resulting from construction and operation, including changes in coastal processes; and Response This comment was based on an indicative search area that took in a substantial part of the coastline and which has now been refined to a smaller proposed development site. The potential impacts of the proposed development upon the setting of scheduled monuments within the refined area have been assessed. A desk-based assessment and walk-over survey has been undertaken, the results of which are provided in Appendices18.1 & Early drafts of the reports were provided to the Western Isles Council archaeologist for comment and approved ( dated 13th January 2011). The potential impacts identified have been considered and assessed as appropriate (Section 18.3 & 18.6) and mitigation measures proposed (Section 18.6). The mitigation measures have been agreed with the WIC archaeologist. Setting impacts upon both designated and undesignated assets, including changes in historic landscape character. Data collection The principal data sources relevant to the archaeology and cultural heritage are shown below in Table Table 188.2: Existing data Data source Coverage Author(s) Year Historic Scotland GIS datasets ( Scotland Historic Scotland 2011 Western Isles Council Historic Environment Record Western Isles CnES 2011 National Monuments Record of Scotland (NMRS) Scotland RCAHMS 2011 Page 3 of 13

4 Table 188.2: Existing data Data source Coverage Author(s) Year Aerial photographs held by NMRS Scotland Various Maps held by National Library of Scotland Scotland Various Various Seazone UK waters UK Hydrographic Office 2011 Ministry of Defence records of losses at sea MoD 2011 Receiver of Wreck (RoW) RoW 2011 Coastal Erosion Assessment for Lewis: A report for Historic Scotland Lewis Burgess, C and Church M The above data sources were augmented by walkover survey and inspection of available geophysical and bathymetric data gathered in 2011 as part of the current project (Appendix 18.1). Study areas Two study areas have been used in the gathering of data (Figure 18.1): Study Area: the land within the development area, which is substantially larger than the final application area. Data for this area was gathered in order to inform the design of the development, identify assets within the construction footprint and to inform the assessment of archaeological potential Outer Study Area: This extends 1km from the study area. Data has been gathered in order to inform the assessment of the applications archaeological potential and identify assets that may be subject to setting impacts. Page 4 of 13

5 Figure 18.1Archaeologucal study areas and Archaeological Assets Page 5 of 13

6 Assessment of significance The significance of the effect imposed by the development is based on the intensity or degree of disturbance to baseline conditions and is categorised into four levels of magnitude, high, medium, low or negligible. The guideline definitions of each of these are given in Table Table 188.3: Criteria for assessing the magnitude of impacts on cultural heritage assets Magnitude effect High Medium Low Negligible of Definition Total loss or major alteration of the cultural heritage asset or The setting of the asset is altered in such a way that its cultural significance is substantially reduced Loss of, or alteration to, one or more key elements of the cultural heritage asset or The setting of the asset is altered noticeably reducing the surrounding s contribution to cultural significance Slight alteration of the cultural heritage asset or The setting of the asset is altered slightly reducing the surrounding s contribution to cultural significance Very slight or negligible alteration of the cultural heritage asset or The setting of the asset is altered very slightly reducing the surrounding s contribution to cultural significance The sensitivity/value/importance of the receptor for each effect is characterised as one of four levels, high, medium, low or negligible. The guideline definition of each level is given below in Table and Table Table 188.4: Sensitivity of cultural heritage assets to physical impacts Receptor sensitivity/ value Cultural heritage Importance Site designations High National Scheduled monuments, Category A listed buildings, and undesignated cultural heritage assets and historic buildings of national importance; also Designated Wrecks or known maritime losses and obstructions where the position is known and positively identified. In addition targets of high potential identified in the geophysical and geotechnical data are considered be of high sensitivity pending further investigation to establish their Page 6 of 13

7 level of significance. Medium Regional Category B listed buildings and undesignated cultural heritage assets and historic buildings of regional importance. Known maritime losses whose position is either unknown or where positive identification is tentative, and targets of medium potential identified in the geophysical and geotechnical data are considered be of medium sensitivity pending further investigation to establish their level of significance. Low Local Category C(S) listed buildings and undesignated cultural heritage assets and historic buildings of local importance; In addition targets of low potential identified in the geophysical and geotechnical data are considered be of low sensitivity pending further investigation to establish their level of significance. Negligible - A badly preserved or extremely common type of archaeological site or building of little value at local, regional or national levels; or targets identified through the assessment of geophysical and geotechnical data that may be of some archaeological interest but that is likely to represent a natural feature Table 188.5: Criteria for assessment of sensitivity of a cultural heritage asset to impacts on its setting Receptor sensitivity/value High Medium Low Negligible Guideline criteria The asset has a clearly defined setting that is readily appreciable on the ground and is vital to its character and value or the appreciation thereof. The asset will generally be readily appreciable on the ground The asset s character and value and the appreciation thereof relate to some extent to its setting. The asset will generally be appreciable on the ground. The asset s surroundings have little relevance to its character and value or the appreciation thereof. The asset is difficult to identify on the ground or its setting is difficult to appreciate on the ground. The asset is imperceptible in the landscape and its character and value or the appreciation thereof does not relate to its surroundings Table combines the definitions of magnitude with the level of sensitivity/value/importance of receptor to provide a prediction of overall significance of the effect. Page 7 of 13

8 Table 188.6: Significance prediction matrix. Magnitude impact of Receptor sensitivity/value Negligible Low Medium High High Negligible Moderate Major Major Medium Negligible Minor Moderate Major Low Negligible Negligible Minor Moderate Negligible Negligible Negligible Negligible Minor 18.5 Existing environment Onshore Full details of the baseline conditions are presented in Appendix A summary is provided here The study area is typical of this part of Lewis, taking in an extensive area of grazing with areas of bog, within which recorded cultural heritage assets predominantly relate to postmedieval agriculture, comprising lazybeds, enclosures, banks and the ruins of abandoned buildings. In this instance, two of the buildings are small mills and small pits associated with the processing of seaweed are also present. A cist (a stone-lined grave, generally of Bronze Age date) recorded in the 1990s but was not found to be evidenced on site (Appendix 18.1). In addition to these recorded assets, there is the reputed location of burials associated with a cattle raid A peat survey has been carried out (Chapter 8: Soils, hydrology and hydrogeology). This has demonstrated that in the area of the construction and hydro electric power plant compounds the peat is no more than 1m in depth and this is generally the case in the onshore pipeline area. In contrast, the peat in the vicinity of the Lambol Burn where crossed by the access track is 3m in depth. Given the proximity of Norse settlement (Siadar and Mealabost Bhuirgh, as demonstrated by place name evidence) the palaeoenvironmental evidence preserved in this deep peat has the potential to inform understanding of the development of the landscape and agriculture during the Norse period Given the archaeological background of this part of Lewis and the size of the study area, it is concluded that there is a moderate potential for previously unrecorded archaeological assets to be present within the study area as a whole. This potential relates primarily to prehistoric assets, which are most likely to be masked by lazybeds and peat In the outer study area, which extends 1km from the study area, there are four scheduled monuments, comprising Teampull Pheadair, chapel (SM 5341), Loch an Duin dun (SM 5364), Clach Stei Lin, stone circle and enclosure (SM 5901) and Steinacleit, homestead and field system (SM 90284). As scheduled monuments these are all considered to be of national importance. Neither Teampull Pheadair nor Loch an Duin dun will have intervisibility with the proposed development and are not considered further Clach Stei Lin (SM 5901) is thought to comprise the remains of a slighted stone circle (only one stone remains standing) and a later enclosure. It is located on a rise some 350m to the south east of the inner study area. The setting of the site can be defined as the rise upon which it is located (Àirigh an Tuim) as the monument may well have been sited here in order Page 8 of 13

9 to render it prominent in the wider landscape. This is no longer readily apparent because of its condition, but the rise contributes to the monument s rather limited sense of place and hence associative value, as it provides expansive views to the west over the sea. The modern bungalows of Airidhantuim are prominent in the foreground of these views. The inner study area is clearly visible from Clach Stei Lin. The onshore elements of the proposed development will lie at least 350m from the monument, beyond the Airidhantuim bungalows Steinacleit (SM 90284) comprises the remains of a massively built prehistoric settlement and enclosure. It has been partially excavated but remains ill-understood and it has been suggested that it represents the remains of a chambered cairn. However, the interpretation favoured by Historic Scotland has been applied here. It is located on a rise overlooking Loch an Duin to the north west and the dun and crannog are clearly visible on the loch. The standing stone Clach an Truiseil is visible to the west and Clach Stei Lin would once have been visible to the north. The location provides generally striking views across the loch to the sea, with the scattered houses of Siadar in the middle distance. The monument s setting may therefore be defined as the rise upon which it is located and the area around Loch an Duin as these are the areas that the occupants presumably farmed. Furthermore the intervisibility with the dun and Clach an Tuiseil contribute to the contextual and associative values of the monument as this helps the visitor appreciate the chronological depth of the landscape. The views to the sea are relevant to its associative value as the monument appears to be placed to overlook the sea and this contributes to its sense of place. Steinacleit lies some 600m to the south of the inner study area. The upper parts of the hydro electric power plant buildings will be visible beyond the modern housing of Siadar at a distance of 1.8km, whilst a small number of the Oyster devices will be visible at a distance of some 2.5km... Offshore No previously recorded cultural heritage assets are present within the offshore boundary of the study area and there is very limited potential for unrecorded assets to be present (Appendix 18.2). The seabed here is composed of exposed bedrock, reflecting the high energy environment. Superficial deposits, which will have included former land-surfaces, have been scoured away by currents. There is limited potential for residual artefacts or debris from wrecks to be trapped in the fissures in the bedrock Impact assessment Indirect physical impacts upon waterlogged deposits have been discounted. The onshore elements of the wave array will not affect the hydrology of the area (Chapter 8 Terrestrial hydrology) and there is therefore no scope for such impacts to occur. Likewise, indirect impacts as a result of changes in coastal processes have been discounted. Owing to the high energy regime, sedimentological changes or changes in the level of erosion occurring are highly unlikely to result from the installation of the Oyster devices, it s supporting infrastructure and its operation (Chapter 7: Physical Environment and Coastal Processes). Hence there is negligible potential for cultural heritage assets to be impacted upon as a result of such changes The potential for setting impacts to occur as a result of the tops of the Oyster devices being visible from the onshore assets has been considered. However, this has been discounted as no assets are present along the shoreline where this might result in a substantive change in cultural value Mitigation is embedded in the design of the development as follows: The development has been designed in order to avoid the removal/disturbance of cultural heritage assets as far as reasonably practicable. Page 9 of 13

10 The development s design minimises potential impacts upon deep peat. The onshore elements have been placed in order to reduce their visibility from designated assets in the surrounding area and to minimise visibility in the landscape generally. Known assets such as lazy bed areas not directly impacted, banks and ruins will be fenced off during construction in order to prevent secondary impacts due to the movement of plant. Do nothing scenario In the do nothing scenario, the onshore baseline would remain essentially unchanged. The assets present are essentially stable, undergoing very slow degradation as a result of natural processes. The only exception to this are features located on the shoreline itself. Such features are likely to be lost to erosion Any offshore assets, which are likely to be restricted to residual artefacts trapped in fissures in the bedrock, are likely to remain stable. Parameters for assessment The assessment has been undertaken based on the Rochdale envelope (Chapter 5 Project description), which provides a range of parameters for the development, with the assessment being based on a worst case scenario involving the maximum land take for the development using directional drilling to install the shore pipelines. It has been assumed that the directional drilling will be undertaken using onshore rigs located within the lazybeds. Figures for land take are presented in Table Table 188.7: calculations of the total area of land taken by the development. Parameter Minimum Area (m 2 ) Maximum area (m 2 ) Onshore pipeline area Hydro-electric power plant compound Temporary construction area Access road construction/widening Shore access track Directional drilling platforms Total with surface laid option Total with directional drilling option Page 10 of 13

11 Potential impacts during construction Impact 1: Removal of areas of lazybeds The construction of the onshore compound and temporary construction compound will remove approximately 0.6ha of lazybeds. Horizontal directional drilling may be used to install the shore pipelines. This may be undertaken from up to two locations within the onshore pipeline installation area, each of which would have a footprint of 30 x 30m. These would almost certainly lie within the lazybeds, resulting in the removal of up to 0.2ha. The construction of the pipelines (if surface laid and maximum eight at 20m width) and access road will remove further areas of the lazybeds Lazybeds are very common in coastal areas of Lewis, and in some areas they continued to be maintained well into the 20 th century. They are, however, an important part of the historic environment as they contribute to the time depth of the landscape and aid in an appreciation of the changing methods of agriculture and patterns of settlement on Lewis and sense of place. It is considered that they are of low sensitivity to impacts The greater part of the lazybeds will remain. However, given that the lines of lazybeds will be visibly broken by the pipelines, if they are to be surface laid it is considered that this will constitute an impact of medium magnitude. It is concluded that the removal of parts of the lazybeds will constitute an adverse impact of minor significance. MITIGATION IN RELATION TO IMPACT 1 The extents and form of the lazybeds will be recorded through rectification of aerial photographs. Residual effect Following mitigation there will remain an appreciable loss to the historic landscape, and it is concluded that the residual impact will remain of minor significance. The impact s effect will be permanent. This is not significant in the terms of the EIA regulations. Impact 2: Potential impact upon previously unrecorded archaeology The construction of onshore elements may result in the removal or disturbance of previously unrecorded archaeological sites. This potential relates to prehistoric and early historic assets. Although the potential for the development area is considered to be low, the area affected by the construction footprint is relatively small and it is considered that the potential for unrecorded assets to be affected by construction is low It is not possible to meaningfully assess impacts upon unknown assets, as both the sensitivity of the asset and the magnitude of the impact are unknown. MITIGATION IN RELATION TO IMPACT 2 Evaluation trenching in the construction area will be undertaken in order to establish the archaeological potential more fully than is possible from non-intrusive studies. Further work will be undertaken as appropriate. Page 11 of 13

12 Residual effect The implementation of the programme of works will allow for the preservation by record of archaeological assets. Although such features will be excavated and hence removed, there will be no palpable loss to the historic environment and a gain in terms of knowledge. It is therefore concluded that the programme of works will completely mitigate any impacts upon unrecorded archaeology. Potential impacts during operation (including maintenance) Impact 1: Impact upon the setting of Clach Stei Lin stone circle and enclosure The tops of the buildings within the onshore compound will be visible from Clach Stei Lin. They will be seen against the backdrop of the sea and in combination with numerous modern cottages. Clach Stei Lin s cultural significance resides in its potential as a data source; it is poorly understood and its intended relationship with its surroundings, beyond the surrounding cultivable land is not clear. Indeed, it is far from certain whether it had any such relationship. It is a relatively slight feature and as such is not widely visible in the landscape. It is concluded that it is of low sensitivity to setting impacts The cultural significance of the asset will be unaffected, by this slight change to its surroundings. It is concluded that the impact will be of negligible magnitude and negligible significance. This is not significant in the terms of the EIA Regulations. MITIGATION IN RELATION TO IMPACT 1 No mitigation is proposed in relation to this impact. Residual effect No mitigation is proposed. The impact is considered to be of negligible significance and will cease upon decommissioning. Impact 2: Impact upon the setting of Steinacleit prehistoric settlement and enclosure The tops of the buildings within the onshore compound will be visible from Steinacleit. They will be seen against the backdrop of the sea and in combination with numerous modern cottages. Steinacleit s cultural significance resides in its potential as a data source, but it also has value as a readily appreciable prehistoric feature. Its visual relationships with other cultural heritage assets in the area, in particular the standing stone at Clach an Tuiseil, also lend it contextual value, as these allow the visitor to appreciate it as a part of the broader prehistoric landscape, rather than experiencing it in isolation. The visual relationships with other assets contribute to its significance, regardless of the precise interpretation of its origins. Therefore it is considered to be of high sensitivity to impacts upon setting The development will be visible from Steinacleit (SLVIA Viewpoint 4), but will not interfere with the appreciation of visual relationships with other assets or landscape features and the closest elements will be seen beyond modern housing. The cultural significance of the asset will be unaffected by this slight change to its surroundings. It is concluded that the impact will Page 12 of 13

13 be of negligible magnitude and minor significance. This is not significant in the terms of the EIA Regulations. MITIGATION IN RELATION TO IMPACT 2 No mitigation is proposed in relation to this impact. Residual effect No mitigation is proposed. The impact is considered to be of minor significance and will cease upon decommissioning. Potential Effects during decommissioning It is considered that there is no potential for impacts during the decommissioning phase; such impacts might occur as a result of ground disturbance, but, following construction mitigation, any archaeology present in areas that will be disturbed during decommissioning will have been removed. Cumulative Effects No cumulative effects have been identified Conclusions The potential impacts upon both the physical fabric and setting of cultural heritage assets have been considered. Following embedded mitigation, which has resulted in the design of the development avoiding impacts as far as reasonably practicable, all predicted impacts are considered to be of minor or lesser significance. Such impacts are not significant in the terms of the EIA Regulations. These impacts comprise the loss of an area of lazybeds, the disturbance of currently unrecorded archaeological features/deposits and a slight change to the setting of two scheduled monuments. Mitigation in the form of a programme of archaeological works has been proposed in order to address the first two, while no mitigation is proposed in relation to the setting impacts. Page 13 of 13