Environmental Assessment

Introduction

The DMRB sets out UK wide guidance on the development of trunk road schemes. The DMRB specifically provides guidance on environmental assessment and describes the level of assessment required at each of the key stages of development of a trunk road scheme.

The primary aim of DMRB Stage 2 assessment is to comparatively assess route options (which may vary, for example by vertical or horizontal alignment or junction layout) and identify a Preferred Route Option. Once the Preferred Route Option is selected, the design is then further developed and assessed at DMRB Stage 3, and the Preferred Route Option is the subject of an Environmental Impact Assessment (EIA) under the relevant legislation.

Taking into account DMRB guidance, the following environmental factors have been subject to environmental assessment as part of the DMRB Stage 2 assessment.

  • Chapter 8: Population - Land Use;
  • Chapter 9: Geology, Soils and Groundwater;
  • Chapter 10: Road Drainage and the Water Environment;
  • Chapter 11: Biodiversity;
  • Chapter 12: Landscape;
  • Chapter 13: Visual;
  • Chapter 14: Cultural Heritage;
  • Chapter 15: Air Quality;
  • Chapter 16: Noise and Vibration;
  • Chapter 17: Population - Accessibility;
  • Chapter 18: Material Assets and Waste;
  • Chapter 19: Climate;
  • Chapter 20: Human Health; and
  • Chapter 21: Policies and Plans.

The assessment of potential impacts and effects on each environmental factor listed above is undertaken in comparison to baseline conditions, which were determined through field survey, desk-based review and consultation. Baseline conditions describe the existing environmental conditions in the defined study area and in the wider area as pertinent to the particular environmental factor.

The general approach to assessment is based on determining the potential for significant effects assessed from a combination of the sensitivity or importance of the environmental receptors and the magnitude of potential impacts. It should be noted that the magnitude and significance reported has been considered assuming embedded mitigation (design measures which are integrated into a project for the purpose of minimising environmental effects) but in the absence of essential mitigation (mitigation critical for the delivery of a project that can be acquired through statutory powers).

For the purposes of the DMRB Stage 2 assessment, construction impacts are considered to be temporary.

Environmental Assessment Summary

Throughout the DMRB Stage 2 Assessment, two aspects are considered:

  • Whether any potential effects would be considered significant; and
  • Whether any of the potential effects identified differ sufficiently between proposed route options that they need to be considered as part of the overall identification of a Preferred Route Option (which considers environmental, engineering and traffic and economic considerations).

The DMRB Stage 2 environmental assessment is summarised in the following paragraphs. Unless otherwise stated, it is assumed that all potential impacts and effects are adverse, therefore the option with the lowest overall effect for each environmental factor would be considered the most favourable and the option with the highest overall effect would be considered the least favourable.

Chapter 8: Population - Land Use

The assessment considers the impacts and effects on land use receptors, including private property and housing, community assets, community land, development land, businesses and agricultural land holdings. The assessment also includes consideration of the potential impacts and effects of land-take, including the need for demolitions, and change in accessibility, including introduction or removal of severance. Commentary is also provided on likely direct/indirect socio-economic impacts.

During construction, it is considered that Option ST2A would have the highest overall effect on Population - Land Use. This is largely as a result of the duration and complexity of construction, and the number and groupings of housing and business properties affected, with potential for direct and indirect impacts on businesses and community assets. Option ST2B is expected to have an intermediate overall effect due to the second longest construction period, with similar consequential effects on Population - Land Use as Option ST2A. Options ST2C and ST2D are anticipated to have the lowest overall effect during construction.

During operation, the differences in impacts and effects on community assets (including their accessibility) and agricultural holdings are not considered sufficient to be a differentiator between proposed route options. Differences in impacts and effects arising from land-take and demolitions on private property & housing and businesses and on development land are considered sufficient to be differentiators. Differences in impacts and effects on community land relating to loss/creation of open space and greenspace is also considered sufficient to be a differentiator. Options ST2C and ST2D are considered to have the highest overall effect on land use and Options ST2A and ST2B are assessed as having the lowest overall effect. 

Chapter 9: Geology, Soils and Groundwater

The assessment considers the impacts and effects to superficial and bedrock geology, soils, land contamination and groundwater (including groundwater reliant receptors, such as private water supplies, ecological habitats and surface water features).

Although there are no differentiators identified in terms of significance of potential effects, with respect to land contamination, there is a significant difference in the procedure required for developing land within the curtilage of Ladywell Landfill site, due to the governance of the site Waste Management License. Options ST2A and ST2B both include infrastructure within the curtilage of Ladywell Landfill site and are considered to have the highest overall effect. Options ST2C and ST2D, which remain outside the curtilage of Ladywell Landfill site, are considered to have the lowest overall effect in relation to land contamination.

Chapter 10: Road Drainage and the Water Environment

The potential effects of each of the proposed route options on road drainage and the water environmental has been considered. The more extensive works on Inchewan Burn associated with Options ST2A and ST2B would result in the potential for significant effects on hydromorphology and surface water quality for this watercourse. Options ST2C and ST2D have the potential for no significant effects and therefore are considered to have the lowest overall effect on road drainage and the water environment. Options ST2A and ST2B are assessed as having the highest overall effect.

Chapter 11: Biodiversity

The assessment has considered the potential impacts and effects on biodiversity resources. These resources comprise a range of species and habitats relating to terrestrial and freshwater ecosystems. Key habitats considered include, the internationally important River Tay Special Area of Conservation (SAC) and sites listed on the Ancient Woodland Inventory (AWI).

The differences in effects on fish species of conservation interest as a result of habitat fragmentation at Inchewan Burn and the loss of areas listed on the AWI are considered sufficient to differentiate between proposed route options. During construction and operation, Options ST2A and ST2B impact Inchewan Burn, with significant effects on fish species of conservation interest arising from permanent, irreversible habitat fragmentation. Option ST2D has the lowest loss of AWI (approximately 17 hectares) with Option ST2A resulting in the highest loss (approximately 21 hectares). Due to the permanent effects on Inchewan Burn, Options ST2A and ST2B are assessed to have the highest overall potential significant effect on biodiversity resources and Options ST2C and ST2D the lowest overall effect.

Chapter 12: Landscape

The assessment has taken account the potential effect of each of the proposed route options on the landscape resource, including the key aspects of the landscape designations through which the proposed route options would pass, including the River Tay (Dunkeld) National Scenic Area (NSA) and its Special Qualities and Murthly Castle, Dunkeld House and The Hermitage Gardens and Designed Landscapes (GDL).

Options ST2A and ST2D have the lowest overall effect on landscape resources, while Options ST2B and ST2C have the highest overall effect. However, it is noted that if the cut and cover tunnel could be developed to allow woodland planting on top of the structure, this would improve the fit with the character of the landscape for Option ST2A, potentially reducing effects on the Special Qualities of the River Tay (Dunkeld) NSA. If this were to be achieved, Option ST2A would be assessed as having the lowest overall effects.

Chapter 13: Visual

The visual assessment considers both the visual amenity and views experienced by people from publicly accessible viewpoints and nearby buildings, including nearby residential properties, and View from the Road, which addresses the predicted effects associated with each option on vehicle travellers.

In terms of views experienced by people from publicly accessible viewpoints, Options ST2A and ST2D are assessed as having the lowest overall effects. For Option ST2A this is largely due to the cut and cover tunnel and the potential landscaping on top of the tunnel section. For Option ST2D, this is largely due to the route being generally on-line and at-grade and therefore closest to the existing baseline condition. Option ST2C is assessed as having the highest overall effect, which is largely due to the inclusion of the raised grade separated Dunkeld Junction.

Option ST2D has the lowest overall effect for Views from the Road, largely as the proposed alignment is on-line and views from the road are not significantly different from the baseline. Option ST2A is assessed to have the highest overall effect as a result of the tunnelled section curtailing views of the surrounding environment.

Chapter 14: Cultural Heritage

The cultural heritage assessment considers the potential for impacts and effects on cultural heritage resources, including archaeological remains, historic buildings and the historic landscape, taking cognisance of relevant legislation and planning policy. The differences in potential for significant effects on historic buildings are considered sufficient to differentiate between proposed route options, whereas the differences in potential effects on archaeological remains and historic landscape are not considered to be differentiators.

As a result of the potential for significant effects on the Category A Listed Dunkeld and Birnam Station including Footbridge, and the complexity and nature of maintaining access to the station during construction, temporary access options for pedestrians and cyclists were also assessed. A short summary of the temporary access options is given below.

  • Access Option 1
    • Extend station platforms to the north to form a temporary station, with vehicular access provided to Platform 2 (northbound), via a new access road from the A822 (Old Military Road) and the replacement of the Highland Main Line railway bridge over Inchewan Burn.
  • Access Option 2
    • Temporary pedestrian footbridge across the A9 construction site, from Birnam Industrial Estate to Dunkeld & Birnam Station, Platform 1 (southbound).
  • Access Option 3
    • Extend station platforms to the north to form a temporary station, with vehicular access provided to Platform 2 (northbound), via a new access road from the A822 (Old Military Road), the replacement of the Highland Main Line railway bridge over Inchewan Burn and a temporary pedestrian footbridge across the A9 construction site, from Birnam Industrial Estate to Dunkeld & Birnam Station, Platform 1 (southbound).
  • Access Option 4
    • Temporary pedestrian footbridge across Inchewan Burn, linking the existing Platform 2 (northbound) and the new access road from the A822 (Old Military Road).
  • Access Option 5
    • Temporary pedestrian footbridge across the A9 construction site, from Birnam Industrial Estate to Dunkeld & Birnam Station, Platform 1 (southbound) and a temporary pedestrian footbridge across Inchewan Burn, linking the existing Platform 2 (northbound) and the new access road from the A822 (Old Military Road).

It is noted that for Options ST2A and ST2B, any of the temporary access options noted above could be utilised to maintain access to the station. However, for Options ST2C and ST2D, Option 2, which can be erected quickly and cheaply, is considered the most appropriate solution. This is the access solution that has been assessed within the environmental assessment for these proposed route options.

Options ST2A and ST2B, incorporating temporary access Option 4, are assessed to have the lowest overall effect. Access Option 4 would necessitate a temporary pedestrian footbridge across the Inchewan Burn, linking the existing Platform 2 (northbound) and the new access road from the A822 (Old Military Road). Options ST2A and ST2B, incorporating temporary access Option 3, are assessed to have the highest overall effect. Access Option 3 would necessitate extending the station platforms to the north to form a temporary station with vehicular access provided to Platform 2 (northbound) via a new access road from the A822 (Old Military Road), the replacement of the Highland Main Line railway bridge over the Inchewan Burn, and a temporary pedestrian footbridge across the A9 construction site linking Birnam Industrial Estate to Platform 1 (southbound) of Dunkeld & Birnam Station.

Options ST2A and ST2B would have a significant beneficial effect on The Category A Listed Dunkeld and Birnam Station including Footbridge, as they re-establish the physical connection between the station and Birnam, via Station Road, potentially facilitating re-use of the station building. There is a lesser beneficial effect for Options ST2C and ST2D due to the improved physical connection to Birnam and the potential future use of the building due to the replacement car park, pedestrian underpass and vehicular access from the A9 for maintenance and emergency access only. However, there would be an adverse effect on the setting of the Category A Listed station building from the permanent loss of the forecourt (now car park) and the close interaction of the proposed route options during operation.

Taking into consideration the beneficial and adverse effects for all proposed route options (including temporary access options) Options ST2A and ST2B with temporary access Option 4 are assessed to have the lowest overall effect. Options ST2C and ST2D with temporary access Option 2 are assessed to have an intermediate overall effect. Options ST2A and ST2B with temporary access Option 3 are assessed to have the highest overall effect.

Chapter 15: Air Quality

The DMRB Stage 2 assessment of air quality on human health and receptors and designated habitats considers air pollutants associated with combustion emissions typically arising from vehicle traffic, comprising oxides of nitrogen (NOx), nitrogen dioxide (NO2) and particulate matter (PM) (PM10 and PM2.5). In relation to sensitive designated habitats, nitrogen (N) deposition is also considered. Dust deposition associated with deposition of PM generated from construction activities and traffic associated with construction works is also considered in the assessment.

The DMRB Stage 2 assessment has determined that the potential human health effects of the proposed route options are not significant as the pollutant concentrations at all assessed receptors are below the objective values set to protect human health. For designated habitats there would be potential for significant effects for all proposed route options. Although there are some differences between proposed route options in terms of number and extent of effects, these are not considered sufficient to be a differentiator between proposed route options.

Chapter 16: Noise and Vibration

The noise and vibration assessment has considered the potential effects on noise sensitive receptors (e.g., residential properties) of road traffic noise generated by the interaction of tyres on the road surface, from engines and exhausts, and from the aerodynamic noise caused by vehicles moving through the air. Vehicle acceleration and speed, road gradients, traffic composition (i.e., percentage of Heavy Good Vehicles in the total number of vehicles) and road surface type influences the noise generated. Additionally, potential effects on noise sensitive receptors arising from construction noise and vibration have also been assessed.

In terms of construction, Option ST2A would have the highest overall effect arising from noise and vibration, due to the requirement for bored piles to construct the 1.5 kilometre cut and cover tunnel and the longest construction duration. Option ST2B is expected to have an intermediate overall effect since it has the second longest construction period and will also require bored piles to construct the 150 metre long underpass. Options ST2C and ST2D are considered to have the lowest overall effect as they have a shorter construction period and require less piling.

During operation of the dual carriageway, Option ST2A is assessed to have the lowest overall noise effect due to the 1.5 kilometre cut and cover tunnel reducing noise effects at noise sensitive receptors as the road passes Birnam. Option ST2B is expected to have an intermediate overall effect due to the lowered carriageway and 150 metre long underpass reducing noise effects at noise sensitive receptors as it passes Dunkeld & Birnam Station. Options ST2C and ST2D are considered to have the highest overall effects, as the proposed carriageway passes noise sensitive receptors at Birnam either at, or above, existing road levels.

Chapter 17: Population - Accessibility

The assessment considers the potential impacts and effects on the journeys made by WCH. This includes consideration of journeys using footpaths, cycle routes and informal access routes to land. While all the proposed route options will affect WCH routes during construction and operation, the differences in effects are not considered sufficient to be a differentiator between proposed route options.

Chapter 18: Material Assets and Waste

The potential environmental impacts and effects related to the use and consumption of material assets and the production and management of waste that can reasonably be anticipated with the construction of the proposed route options have been assessed. It should be noted that operational impacts and effects have been scoped out of the DMRB Stage 2 assessment as they were considered to be not significant (by quantity) in the context of the proposed route options.

The differences in potential impacts and effects between proposed route options during construction on material assets and waste are considered sufficient to be a differentiator. Option ST2A is assessed to have the highest overall effect during construction on material assets and waste, largely due to the significant construction activity involved with the 1.5 kilometre cut and cover tunnel. Options ST2B and ST2C are assessed to have an intermediate overall effect largely due to the 150 metre long underpass and raised at-grade Dunkeld Junction respectively. Option ST2D is anticipated to have the lowest overall effect.

Chapter 19: Climate

The climate assessment considers:

  • The potential effects of the proposed route options on climate, in particular the magnitude of and opportunities to reduce greenhouse gas (GHG) emissions during construction and operation; and
  • The vulnerability of the proposed route options to climate change, in particular, whether anticipated changes to climatic conditions and/or the frequency of extreme events are likely to have significant adverse effects on the project (or elements of the project) during construction and/or operation.

At DMRB Stage 2, due to limited data being available to inform the climate assessment (e.g., material quantities, which are not typically available at this stage), a full assessment of the GHG emissions likely to arise as a result of the construction and operation of each of the proposed route options has not been undertaken. The assessment has therefore focussed on those elements of the construction phase for which data is currently available, namely earthworks, aggregates and soils, whilst also comparing estimated changes in road use GHG emissions associated with each proposed route option.

An assessment of the vulnerability of each of the proposed route options to climate change has not been completed at this stage, as potential climate related impacts are likely to be similar for each of the proposed route options. An element of climate change vulnerability is, however, considered in Chapter 10: Road Drainage and the Water Environment, which considers flood risk.

The differences between potential impacts and effects on climate change during construction are considered to be a differentiator. Option ST2A is assessed to have the highest overall effect during construction, predominantly due to emissions associated with the construction of the 1.5 kilometre cut and cover tunnel. Options ST2B and ST2C would have an intermediate effect largely due to the 150 metre long underpass and raised at-grade Dunkeld Junction respectively. Option ST2D is assessed to have the lowest overall effect on climate.

Chapter 20: Human Health

The World Health Organisation (WHO) defines human health as ‘a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity’. For the purposes of the assessment, human health is considered to encompass both physical and mental health. Although there is no requirement in the DMRB guidance for wellbeing to be assessed, this element has been included in the assessment in response to concerns raised by the local community during the A9 Co-Creative Process.

All proposed route options have the potential for an overall likely negative health and wellbeing outcome during construction. Option ST2A would likely have the highest overall negative outcome on health and wellbeing due to the nature and duration of the required construction activities, which would include extensive piling and excavation. Potential for adverse amenity effects in relation to noise and vibration, landscape amenity and accessibility for a longer duration when compared to the other options were considered to be differentiators. Additionally, Option ST2C was also considered to have a similarly high overall likely negative outcome on health and wellbeing due to severance/separation from healthcare (Craigvinean Surgery) and recreation facilities (Dunkeld and Birnam Recreation Club and Riverside Land) during construction, which may have a disproportionate effect on the young and the elderly who are more likely to use these facilities.

As Option ST2D has the least intrusive construction activities and the shortest construction duration, it is anticipated to have the lowest overall likely negative effect on community health and wellbeing. Option ST2B is anticipated to have an intermediate overall likely negative health and wellbeing outcome owing to it having the second longest anticipated construction duration and the associated noise effects, as well as having adverse visual effects.

During operation Option ST2A is assessed to have an overall likely positive outcome on health and wellbeing due to the potential opportunities for additional green space and landscape amenity, as well as improved amenity for NCN Route 77, which are considered to be differentiators. Options ST2B, ST2C and ST2D are assessed to have an overall likely neutral outcome on health and wellbeing during operation when considering a combination of positive and negative effects across the health and wellbeing determinants.

Option ST2A is therefore considered to have the lowest overall effect for health and wellbeing and Options ST2B, ST2C and ST2D would have intermediate effects.

Chapter 21: Policies and Plans

Whilst the majority of policy compliance assessments are consistent across the proposed route options, it is assessed in policy compliance terms that the main differences between the proposed route options are in relation to road drainage and the water environment and biodiversity assessments. These differences are considered sufficient to be differentiators. Options ST2C and ST2D are considered to adhere greater with policy objectives than Options ST2A and ST2B due to differential hydromorphology and surface water quality impacts upon Inchewan Burn and impacts upon fish species of conservation interest.

Policy non-compliance in relation to Population – Land Use and Cultural Heritage are consistent across the proposed route options and the differences are not considered sufficient to be a differentiator.