Description of main environmental impacts and proposed mitigation

Air quality

Construction activities have the potential to generate short-term, localised air quality impacts. Dust and fine particulate emissions will be generated during the works, from milling of the carriageway surface. The presence of increased HGVs and construction plant presence may contribute to short-term exhaust emissions. TM measures will likely cause congestion and elevated traffic-related emissions during the works.

No likely significant effects are anticipated due to the nature and scale of the works. All air quality effects will be temporary, limited to the construction phase and localised. Following completion of the works, there will be no changes to traffic flow characteristics (composition, speed or flows).

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 road planings will be removed from site as soon as possible (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 method.

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

There are no statutory cultural heritage assets located within the scheme extents, with the single identified feature located over 200m from the scheme. As the scheme involves resurfacing within the carriageway boundary and no ground disturbance beyond previously engineered layers there is no potential for direct physical impacts on any designated cultural heritage features. Additionally, the general topography and presence of vegetation provides visual screening between the works area the designated feature, with no anticipated indirect impacts on setting.

A HER is recorded within the scheme extents; however, it relates to a former heritage desk-based assessment and walkover survey along the A90, with no new heritage sites recorded within 100m and therefore the resurfacing impacts will not result in any adverse impacts on this record.

Original construction of the A90 and associated infrastructure likely removed any archaeological remains. As such, 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 assessment, no further assessment is required.

Landscape and visual effects

The resurfacing works are confined to the existing A90 carriageway and will not alter the existing landscape pattern, quality or distinctiveness within the surrounding area. No designated landscape areas are located adjacent to the scheme extents, and as such no direct landscape impacts are identified. The works will not introduce new permanent landscape changes, with the character of the LCT remaining unchanged post-construction. Operationally, the only visual change will be an improved road surface, with no residual effects on landscape or visual character.

Visual impacts will be limited and temporary, with the closest visual receptor, located 20m from the scheme likely to experience direct, yet short-term views of the works, including artificial lighting and construction presence. However, effects will be limited as all activities will be limited to the carriageway and are to take place overnight for approximately three weeks.

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.
  • Directional site lighting will be used to minimise visual impacts to the identified visual receptors.

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 and artificial site lighting during the night-time works. These may disturb protected species within the scheme surroundings. Japanese knotweed, an INNS has been recorded within 500m, however, as the scheme is confined entirely to the existing A90 carriageway, with no land-take, site clearance, or topsoil import required, there is a limited risk of the spread or introduction of such species.

Drainage infrastructure and surrounding watercourses pose a potential pathway to pollute aquatic habitats, particularly during milling operations and periods of heavy rainfall (see Road Drainage and the Water Environment section for further details).

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 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 precited for biodiversity. Therefore, in line with DMRB Guidance document LA 108: Biodiversity 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. However, the use of WMA which reduces energy demand during production and supports lower carbon emissions. Surfacing also provided enhanced durability and therefore reducing the frequency of future interventions and therefore 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 2018, 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.
  • Waste will be transferred to SEPA-authorised facilities by carriers with valid waste carrier registration. A waste transfer note (WTN) will be completed for removal of waste from site and retained for two years, in line with statutory Duty of Care requirements.

The following mitigation measures will be implemented:

  • 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.

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 operation of planers and construction vehicles may generate temporary increases in noise and vibration. 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 associated with congestion, however, such effects will be brief and limited to the construction period.

No adverse operational noise or vibration impacts are anticipated. The improved road surface will not change the traffic speed, flows or composition and ambient noise levels are expected to return to pre-construction conditions.

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:

  • The delivery of Amey’s Noise and Vibration environmental briefing to all site operatives prior to the works.
  • Notification to Aberdeenshire Council Environmental Health Team due to night-time programming.
  • Letter drops to NSRs to provide advance notification of the works and the programming schedule.
  • Pre-notification of the works through appropriate signage, and/or social media to inform local residents and road users 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 short-term disruption to road users through temporary TM, noise, and delays. The layby serving a bus stop within the scheme extents is likely to be temporarily closed during the works, however, alternative provisions will be implemented, with no permanent change to access or provision post-construction. Similarly, use of the short footway along the scheme extents at Drumlithie Junction will be likely be restricted during the construction period, however an alternative route will be signposted where required.

Local residents and road users will be informed of the schedule and duration of the works via a letter drop and pre-construction notifications, social media updates and signage on approach to scheme extents. Aberdeenshire Council’s Environmental Health Team have been notified of the works.

Human health determinants such as noise, and air quality will likely experience temporary increases, however, due to the nature and scale of the works no discernible health impact is expected.

Please refer to 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 short-term pollution risks to the water environment through accidental spills of fuels, oils, chemicals, or road planings which could enter surface runoff, drainage systems and nearby surface watercourses.

As the works involve resurfacing only, with no in-water works, no abstraction or transfers of water from, or discharges to a waterbody, the potential for a pollution incident within a waterbody is unlikely.

The scheme lies within a NVZ, however, there is no potential for an increase or mobilisation of nitrates as a result of the scheme as the works are limited to resurfacing of the existing carriageway. The scheme lies within a groundwater DWPA, however, as the works are limited to existing engineered layers of the carriageway and do not require deep excavations, the potential for impacts on groundwater quality or mobilisation of contaminants is limited.

The works will not increase flood risk as they are limited to the existing impermeable carriageway surface, 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 follow of SEPA’s Guidance for Pollution Prevention (GPP) documents.
  • The delivery of Amey’s Water Pollution Prevention environmental briefing to all site operatives prior to the works.
  • 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 (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.
  • All storage areas (fuels, machinery, plant, materials) where required will be located and stored:
  • Away (>10m) from surface water drainage systems; and
  • Away from areas that see high vehicular movement (as far as reasonably practicable) to prevent damage by collision or extremes of weather.
  • Fuels stored within a drip tray, bund or other form of secondary containment with at least 110% of the maximum volume of a single container.
  • 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.

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

The use of WMA supports reduced whole-life carbon impacts through a reduced energy demand during production and enabling efficient construction at lower temperatures, compared to hot-mix asphalt (HMA).

Construction activities may result in GHG emissions from vehicles, machinery, material 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.