19.8. Key Parameters for Assessment

The maximum design scenarios (MDS) identified in Table 19.10 Open ▸ are those expected to have the potential to result in the greatest effect on marine archaeology receptors. These scenarios have been selected from the details provided in volume 1, chapter 3 of the Array EIA Report. Effects of greater adverse significance are not predicted to arise should any other development scenario, based on details within the Project Description (volume 1, chapter 3) (e.g. different infrastructure layout), to that assessed here, be taken forward in the final design scheme.

On the basis of the baseline environment and the Project Description outlined in volume 1, chapter 3 of the Array EIA Report, no impacts are proposed to be scoped out of the assessment for marine archaeology.
For direct damage to deeply buried marine archaeology receptors – submerged prehistoric receptors (e.g. palaeolandscapes and associated archaeological receptors), the impact-receptor pathway is through construction activities penetrating the marine sediments to those which represent potentially submerged palaeolandscapes. For this reason, this impact is assessed for the construction phase, but scoped out for the operation and maintenance phase. The direct damage to deeply buried submerged prehistoric receptors is an unavoidable impact that occurs in the construction phase (but is mitigated through the preservation by record of the archaeological resource (see section 19.10.2)). Therefore, direct damage to deeply buried receptors is scoped out for the operation and maintenance and decommissioning phases.
For the alteration of sediment transportation regimes, the presence of infrastructure (e.g. wind turbines and mooring lines) provides the largest obstruction to flow in the water column. For this reason, construction and decommissioning activities are not assessed for this impact.

19.9. Methodology for Assessment of Effects

The criteria for defining magnitude in this chapter are outlined in Table 19.11 Open ▸ . Each assessment considered the spatial extent, duration, frequency and reversibility of impact when determining magnitude which are outlined within the magnitude section of each impact assessment (e.g. a duration of hours or days would be considered for most receptors to be of short term duration, which is likely to result in a low magnitude of impact).

The capability of a receptor to accommodate change and its ability to recover, if affected, is a function of its sensitivity. Receptor sensitivity is typically assessed by its:

adaptability: the degree to which a receptor can avoid or adapt to an effect;
tolerance: the ability of a receptor to accommodate temporary or permanent change without significant adverse impact;
recoverability: the temporal scale over and extent to which a receptor will recover following an effect; and
value: a measure of the receptor’s importance, rarity and worth (Highways England et al., 2019).

Marine archaeology receptors cannot adapt, tolerate, or recover from impacts resulting in damage or loss caused by development. As a result, the sensitivity of a receptor can only be determined through its value.
Based on current guidance, the significance of a historic asset embraces all the diverse cultural heritage values that people associate with it, or which prompt them to respond to it (English Heritage, 2008). Significance is determined by the following value criteria:

evidential value: deriving from the potential of a place to yield evidence about past human activity;
historical value: deriving from the ways in which past people, events, and aspects of life can be connected through a place to the present;
aesthetic value: deriving from the ways in which people draw sensory and intellectual stimulation from a place; and
communal value: deriving from the meanings of a place for the people who relate to it, or for whom it figures in their collective experience or memory. Communal values are closely bound up with historical and aesthetic values but tend to have additional and specific aspects.

Criteria of value for assessing if marine historic assets are of national importance derive from Designation Policy and Selection Guidance (Historic Environment Scotland, 2019) are:

Intrinsic characteristics: how the physical remains of a marine historic asset contribute to our understanding of the past.
Contextual characteristics: how a marine historic asset relates to its surroundings and/or to our existing knowledge of the past.
Associative characteristics: how a marine historic asset relates to people, events and/or historic and social movements.

Criteria of value to shipwrecks specifically are given by Historic England (2012) guidance. These are:

The criteria for defining sensitivity in this chapter are outlined in Table 19.12 Open ▸ .

The magnitude of the impact and the sensitivity of the receptor are combined when determining the significance of the effect upon marine archaeology. The particular method employed for this assessment is presented in Table 19.13 Open ▸ .
Where a range is suggested for the significance of effect, for example, minor to moderate, it is possible that this may span the significance threshold. The technical specialist’s professional judgement will be applied to determine which outcome defines the most likely effect, which takes in to account the sensitivity of the receptor and the magnitude of impact. Where professional judgement is applied to quantify final significance from a range, the assessment will set out the factors that result in the final assessment of significance. These factors may include the likelihood that an effect will occur, data certainty and relevant information about the wider environmental context.
For the purposes of this assessment:

a level of residual effect of moderate or more will be considered a ‘significant’ effect in terms of the EIA Regulations; and
a level of residual effect of minor or less will be considered ‘not significant’ in terms of the EIA Regulations.

Effects of moderate significance or above are therefore considered important in the decision-making process, whilst effects of minor significance or less warrant little, if any, weight in the decision-making process.