Methodology
Introduction
This EAR includes the assessment of the improvement strategies (Improvement Strategies 1-6) which have been assessed as part of DMRB Stage 1. A full description of these improvement strategies can be found in Description of Improvement Strategies.
An outline of the methodologies for each environmental factor is reported within this EAR. These environmental factors are aligned with DMRB LA 101 - Introduction to environmental assessment (revision 0) (hereafter referred to as “DMRB LA 101”), DMRB LA 103 - Scoping projects for environmental assessment (revision 1) (hereafter referred to as “DMRB LA 103”) and DMRB LA 104.
The scope of this EAR covers the following environmental factors:
- Air Quality
- Cultural Heritage
- Landscape and Visual
- Biodiversity
- Geology, Soils and Groundwater
- Material Assets and Waste
- Noise and Vibration
- Population and Human Health
- Road drainage and the Water Environment
- Climate
- Cumulative Effects
Survey Methods
Although there are methods and requirements specific to the assessment of each environmental factor, the approach set out below is common to all environmental factors and is in accordance with relevant guidance and good practice.
This EAR follows the assessment approach set out in the DMRB LA 104. This document was released in July 2019 and further revised in August 2020. It sets out the requirements for the environmental assessment of projects, including reporting and monitoring of significant adverse environmental effects.
Existing baseline environmental conditions have been defined in order to identify the presence of environmental resources and receptors that may be affected by the improvement strategies. These resources and receptors have been identified within defined study areas in order to determine their relative importance or sensitivity towards change. Baseline environmental data, information and records were obtained using a combination of sources and techniques including the following:
- Desk study: a study of previously published information has been undertaken as part of the proposed scheme including; published literature, databases, records and schedules relating to environmental designations, national and local planning policy documents, historic and current mapping and aerial photography.
- Site-based surveys: landscape walkover surveys have been undertaken to verify and consolidate information gathered during the desk-based review, and to evaluate the relationships between specific landscape receptors and their wider environmental value.
General Assumptions and Limitations
Each environmental factor chapter outlines the relevant assumptions and limitations associated with the environmental factor being discussed. Environmental factor specific assumptions and limitations are outlined in each environmental factor chapter. Only landscape surveys have been undertaken during DMRB Stage 1.
Effects that arise during construction, but which may be permanent are identified in the construction phase assessment. Effects that arise during operation are identified in the operation phase assessment. For example, adverse effects from vegetation removal are reported under construction, whilst the beneficial effects of replacement habitat are reported under operation.
The high-level nature of the assessment is reflective of the early stage of design and current level of baseline and survey information. Environmental assessment will adapt and be refined as the proposed scheme progresses through the design stages. For example, additional aspects of environmental factors, or receptors may ultimately be scoped out.
Paragraph 2.6.1 of DMRB LA 104 stresses that the prediction of significant effects does not require absolute certainty. Rather, it is more about taking a reasonable view over likelihood. It is recognised a level of uncertainty is acceptable provided the prediction of likely environmental effects is supported by sufficient evidence. Furthermore, the determination of significance is only expected to be made using readily available information.
It is considered highly unlikely that the proposed scheme would be demolished after its design life as the road is likely to have become an integral part of the infrastructure in the area. In the unlikely event that the proposed scheme is demolished, this would be part of the relevant statutory process at that time, including EIA as appropriate. Demolition was therefore scoped out of the assessment.
This EAR has been prepared based on the environmental baseline information available at the time of writing. Further information will become available as the iterative design and assessment process proceeds and the scope of assessment will be kept under review.
Detailed construction methodologies are unknown at present. For example, the location of site compounds is not available at this stage. Where uncertainty exists, a precautionary approach has been adopted.
Mitigation and enhancement opportunities are identified as potential measures, but no specific mitigation design is included, this is reflective of the early stage of the scheme
The proposed scheme would not introduce any sources of radiation and would generate limited amounts of heat from minor elements such as lighting. The assessment of heat and radiation required under the EIA Regulations 2017 is therefore not relevant to the proposed scheme and has been scoped out. This concurs with DMRB LA 104 which reports ‘heat and radiation is unlikely to be relevant to the scope of most motorway and all-purpose trunk roads’.
Significance Criteria
This EAR addresses the requirements of The Roads (Scotland) Act 1984 as amended by The Roads (Scotland) Act 1984 (Environmental Impact Assessment) Regulations 2017, in presenting: “The description of the likely significant effects” of the proposed scheme on the environment, covering “the direct effects and any indirect, secondary, cumulative, transboundary, short-term, medium-term and long-term, permanent and temporary, positive and negative effects of the project” (refer to Schedule 1A paragraph 6 of The Roads (Scotland) Act (Environmental Impact Assessment) Regulations 2017.
DMRB LA 104 provides advice on typical descriptions of environmental value, magnitude of change (or impact) and significance of effects.
The following sub-sections provide the typical descriptions and explains how the significance of effect category is derived. Assessments against these criteria have been made in accordance with the approaches outlined in the DMRB and on the basis of professional judgement.
Environmental Value (Sensitivity) and Descriptions (Ref Table 3.2N of DMRB LA 104)
The categories and the typical descriptions for sensitivity of receptors as outlined in DMRB LA 104, Table 3.2N, are provided below.
Very High Sensitivity:
Very high importance and rarity, international scale and very limited potential for substation.
High Sensitivity:
High importance and rarity, national scale and limited potential for substitution.
Medium Sensitivity:
High or medium importance and rarity, regional scale, limited potential for substitution.
Low Sensitivity:
Medium or low importance and rarity, local scale.
Negligible Sensitivity:
Very low importance and rarity, local scale.
Environmental Value (Magnitude of Impact) and Descriptions (Ref Table 3.2N of DMRB LA 104)
The categories and the typical descriptions for magnitude of impact as outlined in DMRB LA 104 Table 3.4N are provided below:
Major Adverse Magnitude of Impact (change):
Loss of resource and/or quality and integrity of resource; severe damage to key characteristics, features or elements.
Major Beneficial Magnitude of Impact (change):
Large scale or major improvement of resource quality; extensive restoration; major improvement of attribute quality.
Moderate Adverse Magnitude of Impact (change):
Loss of resource, but not adversely affecting the integrity; partial loss of/damage to key characteristics, features or elements.
Moderate Beneficial Magnitude of Impact (change):
Benefit to, or addition of, key characteristics, features or elements; improvement of attribute quality.
Minor Adverse Magnitude of Impact (change):
Some measurable change in attributes, quality or vulnerability; minor loss of, or alteration to, one (maybe more) key characteristics, features or elements.
Minor Beneficial Magnitude of Impact (change):
Minor benefit to, or addition of, one (maybe more) key characteristics, features or elements; some beneficial impact on attribute or a reduced risk of negative impact occurring.
Negligible Adverse Magnitude of Impact (change):
Very minor loss or detrimental alteration to one or more characteristics, features or elements.
Negligible Beneficial Magnitude of Impact (change):
Very minor benefit to or positive addition of one or more characteristics, features or elements.
No Change Magnitude of Impact (change):
No loss or alteration of characteristics, features or elements; no observable impact in either direction.
Significance Matrix
The significance of an environmental effect is typically a function of the ‘value’ or ‘sensitivity’ of the receptor and the ‘magnitude’ or ‘scale’ of the impact or change. The output of this EAR is to report the likely significance of environmental effects using established criteria as presented in Table 3.8.1 within DMRB LA 104 and reproduced below in Table 4-1.
| Magnitude of Impact (Degree of Change) | No Change | Negligible | Minor | Moderate | Major |
|---|---|---|---|---|---|
|
Very High Environmental value (sensitivity) |
Neutral |
Slight |
Moderate or large |
Large or very large |
Very large |
|
High Environmental value (sensitivity) |
Neutral |
Slight |
Slight or moderate |
Moderate or large |
Large or very large |
|
Medium Environmental value (sensitivity) |
Neutral |
Neutral or slight |
Slight |
Moderate |
Moderate or large |
|
Low Environmental value (sensitivity) |
Neutral |
Neutral or slight |
Neutral or slight |
Slight |
Slight or moderate |
|
Negligible Environmental value (sensitivity) |
Neutral |
Neutral |
Neutral or slight |
Neutral or slight |
Slight |
Significance Categories and Typical Descriptions (Ref Table 3.7 of DMRB LA 104)
The following sub-sections present how the DMRB LA 104 describes the significance of effect categories. In arriving at the significance of effect, the assessor considers whether effects are direct, indirect, secondary, cumulative, short, medium or long-term, permanent or temporary, beneficial or adverse.
Very Large Significance Category
Effects at this level are material in the decision-making process.
Large Significance Category
Effects at this level are likely to be material in the decision-making process.
Moderate Significance Category
Effects at this level can be considered to be material decision-making factors.
Slight Significance Category
Effects at this level are not material in the decision-making process.
Neutral Significance Category
No effects or those that are beneath levels of perception, within normal bounds of variation or within the margin of forecasting error.
The DMRB LA 104, states that the approach to assigning significance of effect relies on reasoned argument and, professional judgement. and taking on board the advice and views of relevant organisations. At DMRB Stage 1 the scheme is at an early stage of design therefore views of relevant organisations have not been sought; this will be completed at the next stages of assessment. The environmental factor chapters provide an assessment of the potential for the proposed scheme to have significant adverse or beneficial environmental effects. The significance of an effect is the result of the importance or value of the resource affected, and the magnitude of the impact upon it.
Those effects categorised as moderate, large or very large are typically considered to be significant. Slight adverse and neutral effects are not considered to be significant. Slight and moderate effects can be borderline cases and whether these effects are considered to be significant is based on professional judgement.
Where appropriate, factor-specific criteria and approaches have been adopted from relevant institute guidelines or good practice. Not all the environmental factors use the above matrix-based approach; for some factors, predicted effects may be compared with quantitative thresholds and scales in determining effect significance. Where quantitative measures may not be applied, qualitative criteria derived from the DMRB have been used.
It is important to note, that significance categories are required for positive (beneficial) as well as negative (adverse) effects. The greater the environmental sensitivity or value of the receptor and greater the magnitude of the impact, the more significant the effect. For example, the consequences of a highly valued receptor suffering a major detrimental impact from the proposed scheme would be classified as a significant adverse effect.