Description of main environmental impacts and proposed mitigation

Air quality

Construction activities may temporarily affect local air quality due to dust and particulate emissions, particularly during milling/planing of the carriageway and excavations associated with the crossover improvement works. Increased HGV movement and construction plant presence may also contribute to short-term exhaust emissions. TM (contraflow, convoy and lane closures) may result in congestion and elevated traffic-related emissions during the works.

However, there are no changes to traffic flow characteristics post-construction (composition, speed or flows) and any air quality impacts will be short-term and localised.

Mitigation measures will follow best practice guidance from the Institute of Air Quality Management (IAQM), from the ‘assessment of dust from demolition and construction (January 2024)’ including:

Site layout will be planned (including plant and vehicles) so that machinery and dust causing activities are located away from receptors, as far as reasonably practicable;
Materials that have a potential to produce dust, such as planings, will be removed from site as soon as possible, unless being re-used on site (cover or fence stockpiles to prevent wind whipping);
Drop heights from conveyors and other loading or handling equipment will be minimised;
Vehicles entering and leaving the work area will be covered/sheeted to prevent escape of materials during transport;
Equipment will be readily available on site to clean any dry spillages and clean up spillages as soon as reasonably practicable after the event using wet cleaning methods.

The following additional mitigation measures will be implemented:

When not in use, plant and vehicles will be switched off and there will be no idling vehicles.
All plant and fuel-requiring equipment used during construction will be well maintained to minimise emissions.

No significant air quality effects are anticipated. Therefore, in line with DMRB Guidance document LA 105: Air Quality no further assessment is required.

Cultural heritage

No designated cultural heritage features are located within the scheme extents, and no land acquisition is required. All works are confined to the existing carriageway boundary, with no significant vibration effects anticipated due to the nature and scale of the works. As such, no impacts are anticipated to the closest listed building located 35m from the scheme.

No impacts are identified to the non-extant HERs as they are documentary records only. The extant HERs located within the scheme extents are unlikely to be affected, as the original construction of the A90 likely removed any historic remains, and the potential for unknown archaeology is considered low.

The following mitigation measures will be in place:

Plant and machinery will be stored within the carriageway boundary where practicable.
Any access beyond the carriageway will be minimised and ideally limited to foot access.

No significant effects are anticipated to cultural heritage. Therefore, in line with DMRB Guidance document LA 106: Cultural Heritage, no further assessment is required.

Landscape and visual effects

Short-term impacts on landscape character and visual amenity for nearby visual receptors may occur during construction due to the presence of TM, plant, vehicles and artificial lighting. While many visual receptors are partially screened, approximately three have a direct view of the works and therefore may experience a higher level of temporary visual intrusion during the construction period. Such effects will remain limited and short-term, as all works are confined to the A90 carriageway boundary. No residual landscape or visual impacts are anticipated post-construction, with the improved road surface and crossovers being the only visible change, both of which are consistent with the existing trunk road setting.

The following mitigation measures will be in place:

The site will be kept clean and tidy throughout all stages of the works, with appropriate storage of materials, equipment, plant and waste.
Works will avoid encroaching on land and areas where work is not required or not permitted, including for storage and parking.

No significant effects are anticipated upon the landscape and visual effects. Therefore, in line with DMRB Guidance document LA 107: Landscape and Visual Effects no further assessment is required.

Biodiversity

Construction activities have the potential to cause temporary adverse impacts on biodiversity due to vehicle presence, noise, excavation and additional artificial site lighting that will be required during the night-time works. This may disturb protected species within the scheme surroundings.

No INNS have been recorded within the scheme extents, and with no land-take, site clearance, or imported topsoil required, there is limited risk of introduction or spread of INNS. There is no anticipated impact to the adjacent areas of AWI woodland as works are contained to the existing carriageway boundary, with no vegetation clearance required.

There is a potential risk of indirect pollution to aquatic habitats, particularly during milling operations and excavations within the central reserve at crossover locations, and periods of heavy rainfall (see Road Drainage and the Water Environment section for further details).

Due to the proximity of the scheme to the River South Esk SAC, a HRA has been undertaken. No direct impacts are anticipated to the designated site as the works are confined to the existing carriageway, and no hydrological connectivity is identified. Pollution prevention measures will be in place as standard best practice. Additionally, no significant effects are anticipated as:

The habitat area of the European Site will not be reduced as a result of the scheme.
There will be no long-term disturbance to key species as a result of the scheme.
No habitat or species fragmentation will occur as a result of the scheme.
There will be no reduction in species density as a result of the scheme.
There will be no change in the key indicators of conservation value.
The scheme works will not reduce the ability of the designated site to cope with climate change.

The following mitigation measures will be in place:

A ‘soft start’ procedure with regard to plant, machinery and vehicles will be implemented daily to gradually increase noise levels and minimise disturbance.
Directional site lighting will be used, aimed away from sensitive ecological features such as adjacent woodland and watercourses.
Plant, vehicles and materials will be contained to areas of engineered ground and not stored on grass verges as far as reasonably practicable. Any damaged areas will be reinstated post-works.
If a protected species is encountered, works will be paused and advice sought from Amey’s Environmental Team.
Additional pollution prevention measures are detailed in the Road Drainage and the Water Environment section.

With these mitigation measures in place, no significant effects are predicted for biodiversity. Therefore, in line with DMRB Guidance document LA 108: Biodiversity no further assessment is required.

Geology and soils

Construction activities, including overlay resurfacing and crossover improvement works will be contained to the existing A90 carriageway boundary, resulting in limited potential for soil disturbance. In the absence of mitigation, there is a risk of pollution to soils from accidental spills or leaks of fuels and oils from construction plant and machinery, as well as from excavation activities. However, any impact is expected to be minor and temporary, with no significant effect on the function or quality of local geology and soils.

The following mitigation measures will be in place:

Vehicles and materials will not be stored or parked on grass verges where possible. Where damage occurs, reinstatement will be undertaken.
Excavated material from crossover works will be used as backfill where possible.
Pollution prevention measures outlined in the Road Drainage and the Water Environment section will be followed during construction.

With mitigation measures in place, no significant effects are anticipated on geology and soils. Therefore, in line with DMRB Guidance document LA 109: Geology and Soils no further assessment is required.

Material assets and waste

There is potential for resource depletion through the use and transportation of primary materials such as aggregates, asphalt, concrete, steel barriers and posts. However, the use of recycled content within asphalt and reuse of excavated materials will help mitigate long-term resource use.

Potential impacts related to pollution from materials and waste may result if these are not appropriately managed during construction. Therefore, the following regulatory requirements will be adhered to:

A SWMP will be prepared prior to the works which will detail how resource use and waste will be managed. This will help control and reduce the amount of waste produced, resulting in less landfilled waste.
The Contractor is responsible for the management and disposal of road planings arising from the works. All waste will be managed in accordance with the Environmental Authorisations (Scotland) Regulations 2025, under the relevant SEPA waste authorisation for recovery, reuse or disposal. For example, road planings will be prioritised for recovery or reuse, through recycling into new asphalt, in line with the waste hierarchy. Landfill disposal will only be considered where recovery or reuse options are not practicable.
All waste will be disposed of at SEPA-licenced facilities by carriers with valid waste licences. A waste transfer note (WTN) will be completed every time waste is removed from the site and retained for two years.

The following mitigation measures will be implemented:

Operators will follow duty of care protocols for the safe handling, storage, and transfer of waste. This includes maintaining proper documentation and the use of licensed carriers.
Waste will be stored in suitable, covered containers, and segregated at the source where possible.
The waste hierarchy (Reduce, Reuse, Recycle and Dispose) will be employed throughout the construction works.
Good materials management methods (e.g., ‘just-in-time’ delivery) will be used to minimise and prevent the disposal of unused materials.
Containment measures will be in place to prevent debris or pollutants from entering the surrounding environment.
Excavated material from excavations associated with the crossover and VRS works will be used as backfill as far as possible to minimise off-site disposal.

With best practice mitigation measures in place, no significant effects are predicted for materials and wastes. Therefore, in line with DMRB Guidance document LA 110: Material Assets and Waste no further assessment is required.

Noise and vibration

Construction activities, particularly milling and the use of machinery such as planers and construction vehicles may cause temporary noise and vibration impacts. These are not expected to significantly exceed ambient levels or result in notable disturbance to surrounding NSRs, in particular due to the high baseline noise levels. TM may also contribute to short-term increases in noise due to congestion.

Post-construction, no adverse noise or vibration impacts are anticipated. The improved road surface and crossover installation and upgrades will not change the traffic speed or flows. Ambient noise levels are expected to return or become lower than pre-construction conditions due to the improved surfacing, from concrete to asphalt and resulting smoother road surface.

Mitigation measures follow Best Practicable Means as outlined in British Standard (BS) 5228:2009+A1:2014. The standard provides specific detail on suitable measures for noise control in respect to construction operations; for example:

Quiet working methods will be employed, including use of the most suitable plant, reasonable hours of working for noisy operations, and economy and speed of operations.
Effects from noise will be kept to a minimum through the use of appropriate mufflers and silencers fitted to machinery. All exhaust silencers will be checked at regular intervals to ensure efficiency.
Operations will be sequenced to minimise simultaneous use of high-noise equipment, and a ‘soft start’ to works will be in place, whereby plant, machinery and vehicles are started sequentially as opposed to simultaneously.
Plant and machinery will be regularly maintained to prevent excessive noise from worn parts or inefficient operation.
On-site construction tasks will be programmed to be as efficient as possible, with a view to limiting noise disruption to local sensitive receptors. Where night-works are to be undertaken, the noisiest works will be undertaken before 23:00 where possible.

The following further mitigation measures related to noise and vibration will be in place:

Amey’s Noise and Vibration environmental briefing will be delivered to all site operatives before works start.
Angus Council Environmental Health Team has been notified of the works due to night-time programming.
A letter drop will be delivered to NSRs as a pre-construction notification of the works and programming schedule.
Engagement and pre-notification of the works through social media will be undertaken prior to commencement of the works, to make road users and local residents aware of the upcoming works.

With best practice mitigation measures in place, no significant effects on noise and vibration are predicted. Therefore, in line with DMRB Guidance document LA 111: Noise and Vibration no further assessment is required.

Population and human health

Construction activities may cause temporary disruption to road users due to TM, noise, and delays.

There is no anticipated impact to the core paths located within the scheme surroundings, as they are located outwith the scheme extents with no alternative WCH arrangements are required during the works.

Road access points within the scheme extents may be temporarily affected during construction, however, access will be maintained and granted where required. Local residents and road users will be informed of the working schedule, in particular the times and durations of the works through a letter drop and pre-construction notice of the works which include journey planning via social media; and signage on approach to scheme extents. Directional lighting will be used to avoid nuisance to nearby properties during the night-time works.

Angus Council’s Environmental Health Team has been notified of the works.

Please see the Landscape and Visual Effects section above for an assessment of the visual impacts to visual receptors.

With best practice mitigation measures in place, no significant effects on population and human health are anticipated. Therefore, in accordance with DMRB Guidance document LA 112: Population and Human Health, no further assessment is required.

Road drainage and the water environment

Construction activities may pose a risk of indirect pollution to the water environment from spills of fuels, oils, chemicals, and road planings and excavated materials entering surface runoff and drainage systems. Keithock Burn flows beneath the carriageway, which could act as a pathway for pollutants. However, as it is a contained culvert beneath the carriageway, with no in-water works, abstraction or transfers of water from, or discharges to a waterbody, the potential for a direct pollution incident within a waterbody is unlikely.

The works will not increase flood risk as they are limited to the existing impermeable carriageway surface and central reservation, with no alteration to drainage infrastructure or surface water runoff patterns. No other post construction impacts are anticipated.

The following best practice and pollution prevention and control measures will be in place:

All operatives will be aware of SEPA’s Guidance for Pollution Prevention (GPP) documents.
All debris which has the potential to be suspended in surface water and wash into the local water environment will be cleaned from the site both during and following the works.
All site operatives will be made aware of site spillage response procedures and in the event of a spill all works associated with the spill will stop, and the incident reported. Spill kits will also be available within all site vehicles and spill kits will be replenished onsite when required.
The Amey control room will be contacted if any pollution incidences occur (available 24 hours, 7 days a week).
In the event of a pollution incident, SEPA will be notified without delay.
Weather reports will be monitored prior to and during the works with all construction activities temporarily halting in the event of adverse weather or a flooding event. The works will only continue when it is deemed safe to do so and runoff/ drainage can be adequately controlled to prevent pollution.
Where refuelling on site is required, there will be designated refuelling areas, located more than 10m from surface water drainage systems, and within hard standing and bunds to prevent leaks or spills escaping.
Concrete curing for VRS foundations will be protected/covered from precipitation to prevent runoff contamination.
Mixing of concrete on site will be undertaken >10m from watercourses and surface water drainage systems.
No washout from concrete mixing will enter the water environment and will be taken off site for appropriate treatment.
Amey’s Water Pollution Prevention environmental briefing will be delivered to all site operatives before works start.

With mitigation measures in place, no significant effects are anticipated on the water environment. Therefore, in line with DMRB Guidance document LA 113: Road Drainage and the Water Environment no further assessment is required.

Climate

Construction activities may result in GHG emissions from vehicles, machinery, material use and production, and transportation. However, given the nature of the scheme, the volume of materials required to be imported on site is low, reducing the overall impact.

The following mitigation measures will be in place:

Where possible, materials and suppliers will be sourced locally to reduce GHG emissions associated with travel distance.
Waste disposal will be directed to local licensed facilities.
Plant, machinery and vehicles will not be left idling when not in use.
Further actions and considerations for this scheme are detailed in the above Material Assets and Waste section.

With best practice mitigation measures in place, no significant effects are anticipated on Climate. Therefore, in line with DMRB Guidance document LA 114: Climate, no further assessment is required.

Vulnerability of the project to risks

Construction activities are confined to the carriageway boundary, reducing the risk of major accidents or environmental disasters. Furthermore, TM will be designed in line with existing guidance. TM will comprise of a convoy system, with no full road closure or diversion routes required.

Considering the above, the vulnerability of the project to of major accidents and disasters is considered to be low.

Assessment cumulative effects

Angus Council’s Planning Portal have not identified any extant planning applications surrounding the scheme extents that would result in any in-combination effects.

The Scottish Road Works Commissioner’s Interactive Map has not highlighted any works during the proposed timescale at the location of the works.

Amey’s current programme of works has not identified any other works on the A90 that will be undertaken in conjunction with the scheme. Any future schemes will be programmed to consider already programmed works, and as such any effect (such as from TM arrangements and potential construction noise) will be limited.

During construction, activities associated with the works may have minor temporary disturbances such as changes to noise and vibration and air quality, and potential disturbance to local wildlife.

The scheme is not anticipated to have significant environmental effects having regard to its nature, scale and location. The residual impacts arising from the works can be appropriately mitigated and thus no cumulative or in-combination effects are anticipated.

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