Air quality

Impacts

• During the construction phase, activities undertaken on site could potentially have some minor localised and short-term air quality impacts in proximity to the works:
• Construction activities, including excavation, carry a potential to produce airborne particulate matter, dust and generate emissions;
• Various plant, vehicles, and Non-Road Mobile Machinery (NRMM) will contribute to local dust, particulate matter and exhaust emissions.
• The impacts identified will be temporary for the duration of the works only and therefore no change is predicted on air quality.
• Post construction there will be no change to the traffic volume, speed or road alignment.

Mitigation

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

• Remove materials that have a potential to produce dust from site as soon as possible, unless being re-used on site (cover or fence stockpiles to prevent wind whipping);
• Only use cutting, grinding or sawing equipment fitted or in conjunction with suitable dust suppression techniques such as water sprays or local extraction, e.g. suitable local exhaust ventilation systems;
• Minimise drop heights from conveyors and other loading or handling equipment;
• Ensure vehicles entering and leaving the work area are covered to prevent escape of materials during transport;
• Ensure equipment is 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; and
• When not in use, plant, vehicles and NRMMs will be switched off and there will be no idling vehicles.

The following additional mitigation measures will be implemented:

• Green driving techniques will be adopted, and effective route preparation and planning undertaken prior to works.
• Plant, vehicles and Non-Road Mobile Machinery (NRMM) will be regularly maintained, paying attention to the integrity of exhaust systems to ensure such fuel operated equipment is not generating excessive fumes.

No significant effects are anticipated and therefore no further assessment in accordance with DMRB Guidance document LA 105: Air Quality is required.

Cultural heritage

Impacts

• The works located partially within the Antonine Wall Scheduled Monument and World Heritage Site, present a potential risk of archaeological interest or disturbance. While the works are not expected to cause direct damage to the integrity of the monument, their proximity necessitates careful planning and oversight.
• The setting of the assets in question is likely to be temporarily impacted by the proposed scheme given the presence of plant, machinery, vehicles and operatives.
• Due to the nature of the works and proposed construction activities, any effects associated within vibration are likely to be minimal and temporary.

Mitigation

The following mitigation measures will be in place throughout the period of works:

• All site staff will be made aware of the Antonine Wall Scheduled Monument during all phases of works.
• If any archaeological finds are discovered, the works will be suspended, and the relevant stakeholders will be contacted.
• No materials or wastes will be stored within any of the designated site’s boundaries.
• During construction, plant, vehicles, personnel, materials etc. will be contained to hard land at all times.
• Further actions and considerations for the scheme are detailed in the Noise and Vibration, Air Quality and Landscape sections of this report.
• Consultation was undertaken with Historic Environment Scotland (HES) to ensure compliance with heritage protection regulations and to safeguard the site's cultural significance.

Consultation with Historic Environment Scotland (HES) has confirmed that activities within the Antonine Wall Scheduled Monument will not require Scheduled Monument Consent for Phase 1 activities, provided the following conditions are met:

• Fencing within the Scheduled Monument must be cut by hand at ground level;
• Any temporary fencing within the Scheduled Monument must be free standing and not penetrate the ground, and;
• Vegetation removal can only be carried out if vegetation is cut at the base with roots left in the ground.

Consultation with the West of Scotland Archaeology Service (WoSAS) has been undertaken. This consultation has concluded the following:

• Any ground-disturbing works within the Antonine Wall Scheduled Monument must be agreed within HES;
• Vegetation must be cut only to ground level, and the ditch must be cleaned only to its original edges, and;
• The site compound should be built by laying geotextile on the existing ground or located in an area where it is known that the ground has already been substantially reduced.

Provided mitigation measures are followed 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

Impacts

• There will likely be a short-term impact on the landscape character and visual amenity of the site as a result of the presence of construction plant, vehicles, and TM.
• Users of the footpaths will experience diminished visual amenity as a result of construction activities. The presence of machinery and fencing will disrupt the visual quality of these recreational areas.
• TPO CDC7 will not be affected by the proposed works, as all activities will be contained within the defined scheme extents.
• Vegetation clearance (Phase 1) has the potential to alter the established natural setting and landscape character of the Antonine Wall Scheduled Monument.
• Ditch clearance and fence upgrades may result in a minor positive visual effect for users of the adjacent footpath, as the removal of overgrown vegetation may enhance the overall appearance of the surrounding landscape.

Mitigation

• Plant, vehicles, and materials will be confined to hardstanding areas (as far as reasonably practicable).
• Throughout all stages of the works, the site will be kept clean and tidy, with materials, equipment, plant and wastes appropriately stored, reducing the landscape and visual effects as much as possible. 
• Vegetation cutback (where required) will be minimal and only where necessary. Should any tree roots be removed, the Amey Landscape Team will be notified.
• Where any damage occurs to the soft estate/exposed soil (e.g. during the presence of plant, machinery, vehicles, operatives and compound/welfare facilities), areas will be reinstated upon completion of the works. Reinstatement will include removal of existing topsoil, with fresh topsoil and seeding with same mix/species as was there before works being installed thereafter.
• The fence line will be designed to remain in-keeping with the surrounding environment to maintain landscape character and integrity.

With mitigation measures and best practice in place, it is anticipated that any landscape and visual effects associated with the works will not be significant. Therefore, in accordance with DMRB Guidance document LA 107: Landscape and Visual Effects, no further assessment is required.

Biodiversity

Impacts

• There is potential for protected species to be active within the surrounding area and for the works to result in disturbance to these species via noise pollution and habitat destruction. 
• There is the potential for nesting birds to utilise the woodland/scrub within/parallel to the area of works in areas where vegetation cutback is required. Therefore, nesting birds have the potential to be impacted by the proposed scheme should works be undertaken within nesting season. 
• Vegetation clearance and excavations required could result in habitat loss. 
• Works have the potential to disturb and spread target species and INNS, such as Himalayan balsam, if located within the scheme extents.

Mitigation

• As it is possible that Himalayan balsam occurs within the scheme extents, site operatives will be briefed on the on the species and control measures through a toolbox talk. Biosecurity measures will be put in place including machinery washdowns to prevent soil movement to other sites after work completion, and caution will be taken when working in the drainage ditch or adjacent to the stream.
• Vegetation clearance will be programmed outwith breeding bird season (which is from March – August inclusive). Where this cannot be avoided, a suitably qualified/experienced ecologist will carry out a nesting bird check before works can proceed during breeding bird season. Nesting bird checks will be undertaken no more than 48 hours prior to any clearance works taking place.
• Where possible, felled trees and woody shrubs will be left behind in piles providing refugia.
• Standard construction safeguards for mammals will be adhered to at all times whilst construction is ongoing including that all compounds, storage areas and excavations will be fenced with mammal proof fencing and a ramp provided in any excavations left overnight.
• ‘Soft start’ techniques will be utilised with noise heavy equipment/plant/machinery in order to avoid disturbance to any potential noise sensitive species present in the area.
• Additional pollution prevention measures are detailed in the Road Drainage and the Water Environment section.

With the above mitigation measures and best practice being adhered to, no significant effects on biodiversity are anticipated. Therefore, in accordance with DMRB Guidance document LA 108: Biodiversity, no further assessment is required.

Geology and soils

Impacts

• The works may result in minor soil disturbance, which can create adverse conditions, including erosion and polluted soils.
• There is potential for spills, leaks or seepage of fuels and oils associated with machinery to escape if not controlled which may negatively affect the soil environment.
• Removing vegetation and topsoil can reduce organic matter in the area.

Mitigation

The following mitigation measures will be in place during the works:

• There will be no unnecessary storage of materials or parking of vehicles on soft ground or grassy areas, as this may destroy the soil structure and damage grass. Hardstanding will be provided. If damage occurs re-instalment will be carried out as specified in the relevant Landscape and Visual Effects section (above).
• Spill kits will be present on site, and all operatives will be fully trained in their use. Any fuels or chemicals required for use will be stored securely with drip trays used appropriately and stored under any chemical or fuel containers. 
• Weather reports will be monitored prior to the works, with all construction activities temporarily halting in the event of predicted high rainfall or wind.
• See additional pollution mitigation measures in the Drainage and Water Environment section below.

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

Impacts

• There will be an increase in waste to landfill if waste materials are not recycled or reused, and therefore by reusing any excavated material the volume of waste sent to landfill will be reduced.
• The use of virgin aggregates within the scheme will contribute to the depletion of natural and finite geological resources.
• Energy will be required for the scheme in the form of non-renewable fossil fuels for transport of materials and personnel, and for plant operation. The use of non-renewable fuels to power plant and machinery will be a contributing factor to greenhouse gas emissions.

Mitigation

• Where possible, materials will be obtained locally, and operatives deployed from the local depot to reduce haulage and scheme associated journeys, reducing impact of associated Greenhouse Gases (GHG) emissions on climate change.
• The contractor will adhere to waste management legislation and ensure they comply with waste management Duty of Care.
• Materials will be derived from recycled, secondary or re-used origin as far as practicable within the design specifications to reduce natural resource depletion and associated emissions.
• Battery operated plant, vehicles and machinery will be explored as a resource-friendly alternative to combustion fuel powered counterparts.
• Vegetation will be stacked and/or chipped and re-distributed on site where possible.
• Waste will be transferred to SEPA-authorised facilities by carriers with valid waste carrier registrations. 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.

Waste plant matter may be treated at the place where it is produced to make it easier to transport or to produce mulch for use at the place of production. However, treatment must occur at the place where the waste plant matter or brash was produced. Please see SEPA guidance for details. 

It has been determined that the proposed project will not have direct or indirect significant effects on the consumption of material assets or creation of waste. Therefore, in accordance with DMRB Guidance document LA 110: Material Assets and Waste, no further assessment is required.

Noise and vibration

Impacts

• There will be an increase in noise and vibration levels during construction due to the use of plant and machinery and an increase in HGVs, thus having an impact on nearby residential and non-residential receptors, particularly due to the low-background levels currently being experienced within the surrounding area.
• The works are not likely to change the existing baseline noise level post construction for any sensitive receptors.
• Noisy and vibration-heavy works will likely be required, which could cause disturbance for residential properties within 300m of the scheme extents, and for the nearby amenity users.

Mitigation

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:

• 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.
• The use of battery-operated plant, vehicles and machinery will be explored for the proposed scheme extents to reduce noise levels of equipment.
• The site supervisor will monitor the effects of noise and vibration levels during the works and make necessary working arrangements.

With best practice mitigation measures in place, and due to the works being of a minor, transient nature, no significant effects are predicted for noise and vibration. Therefore, in accordance with DMRB Guidance document LA 111: Noise and Vibration, no further assessment is required.

Population and human health

Impacts

• Footways and West Dunbartonshire Council Core Paths running parallel to, and through the proposed area of works have the potential to be impacted by the proposed scheme.
• Temporary land take is required for works to commence as the scheme extents are located on private property and land owned by Scottish Ministers.
• Loss of vegetation may increase visual exposure altering views for users of the footpath within the scheme extents.
• Specific impacts on air quality, visually and regarding noise and vibration can be found within the relevant sections of this document.

Mitigation

• Footpaths adjacent to the works will remail open, however, if closures are necessary, they will be discussed with the local authority and advertised upon approach. Where appropriate, accessible diversion routes will be provided and will be well sign-posted.
• Discussions with landowners are required to secure all necessary permissions prior to commencing works. Detailed information on planned construction activities and the programme of works will be communicated, with timely updates provided to landowners in the event of any changes.
• See additional Landscape and Visual Effects mitigation measures, Noise and Vibration mitigation measures and Air Quality mitigation measures in the appropriate sections above.

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

Road drainage and the water environment

Impacts

• Potential for spills, routine runoff, leaks or seepage of fuels and oils associated with plant to escape and/or leach into the watercourse if not controlled, which may negatively affect the surrounding water environment and surface/ground water quality.
• If not adequately controlled, debris and runoff from the works could be suspended in the surface water. In the event of a flooding incident, this debris may be mobilised and could enter the drainage system, thus having a detrimental effect on the surrounding local water environment.
• This scheme will have a positive impact to road drainage, as works are being undertaken to reduce flooding in the area.

Mitigation

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

• 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.
• Prior to works commencing, all operatives will be aware of SEPA’s Guidance for Pollution Prevention (GPP).
• Appropriate measures will be implemented onsite to prevent any potential pollution to the natural water environment (e.g., debris, dust, and hazardous substances). This will include spill kits being present onsite at all times, and the use of funnels and drip trays when transferring fuel etc.
• The control room will be contacted if any pollution incidences occur (available 24 hours, 7 days a week).
• Weather reports will be monitored prior and during all construction activities. In the event of adverse weather/flooding events, all activities will temporarily stop, and only reconvene when deemed safe to do so, and run-off/drainage can be adequately controlled to prevent pollution.
• Visual pollution inspections of the working area will be conducted in frequency, especially during heavy rainfall and wind.

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

Climate

Impacts

• Construction activities may result in GHG emissions from vehicles, machinery, material use and production, and transportation.

Mitigation

The following mitigation measures will be in place:

• Local suppliers will be used as far as reasonably practicable to reduce travel time and GHG emitted as part of the works.
• Vehicles/plant will not be left on when not in use to minimise and prevent unnecessary emissions.
• Further actions and considerations for this scheme are detailed in the above Material assets and waste section.

With best practice mitigation measures in place, the residual significance of effect on climate is considered to be not significant. Therefore, in accordance with DMRB Guidance document LA 114: Climate, no further assessment is required.

Vulnerability of the project to risks

Construction activities are confined to the works location, and maintenance will not significantly impact the surrounding environment. The drainage design is required to account for any anticipated future increases in precipitation and flood events and therefore construction and operational impacts on flooding have been assessed as negligible.

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

Assessment cumulative effects

Due to the final construction programme for the scheme not yet having been confirmed, it is not possible to identify any road works, planning applications or other nearby works contributing to cumulative effects at this time. However, according to the Scottish Road Works Commissioner and West Dunbartonshire Council, no concurrent or overlapping works are scheduled within the vicinity of the proposed construction activities.

Any future schemes will be programmed to take into account already programmed works, and as such any effect (such as from TM arrangements and potential construction noise) will be limited.

Overall, it is unlikely the proposed works will have a significant cumulative effect with any other proposed works in the local area. Considering the nature and scale of the maintenance works being undertaken, no cumulative or in combination effects are anticipated.