Description of main environmental impacts and proposed mitigation

Air quality

Construction activities associated with the various works on the Bridge may temporarily impact local air quality surrounding the Bridge for the period of the works. Activities such as carriageway resurfacing, nosing joint repairs and concrete repairs may emit dust and particulate matter emissions. Increased HGV and construction plant presence may also contribute to short-term emissions. TM will likely cause 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.

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:

  • Materials that have a potential to produce dust will be removed from site as soon as possible, unless being re-used on site (cover or fence stockpiles to prevent wind whipping);
  • Cutting, grinding or sawing equipment will be fitted or used in conjunction with suitable dust suppression techniques such as water sprays or local extraction, e.g. suitable local exhaust ventilation systems;
  • 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;
  • Surfaces will be swept where loose material remains, for example following planing; and
  • Containment measures such as scaffolding and sheeting will be in place to contain debris and dust during the external painting works.

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

Cultural heritage

The Bridge is a Category A Listed Building, with the works therefore having potential impacts with regard to this designation. The works, however, are required to ensure the long-term viability and structural integrity of the Bridge and therefore protecting and maintaining a statutory heritage asset.

As works consist largely of maintenance and like-for-like replacements with no anticipated visual, or character changes to the Bridge, no significant adverse impacts are anticipated due to the works.

There is no anticipated impact to the Scheduled Monument, Conservation Area or World Heritage Site located within 300m as the works are contained to the existing footprint of the Bridge. Furthermore, the Bridge stands a prominent feature in the landscape, and thus the works are not anticipated to introduce significant visual impacts or impact views to or from the identified designated heritage features.

The potential for exposure of undiscovered cultural heritage features is not anticipated as construction of the Bridge is likely to have removed any archaeological finds that may have been present, and with works contained to the existing structure, there are no anticipated impacts upon the identified cultural heritage features within the surrounding study area.

The following mitigation measures will be in place:

  • As part of the marine licensing process, initial consultations with Historic Environment Scotland (HES), Renfrewshire Council and West Dunbartonshire Council were undertaken. HES had no comments to make, while the relevant local authorities were content that listed building consent would not be required due to the works operating on a generally like-for-like basis. Further consultations will be undertaken on a scheme-by-scheme basis prior to works activities if there is to be a change to the character or appearance of the Bridge, which may give further consideration to the requirement for appropriate consents.
  • All site operatives will be informed of the historical value of the Bridge, and its designated status.

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

Due to the setting of the Bridge, a number of residential, community, commercial and industrial and recreational receptors have a direct sight of the Bridge. Temporary adverse impacts on visual receptors are anticipated during the construction phase(s) of the works due to the presence of plant, machinery, TM and vehicles. This is particularly relevant where external painting works are being undertaken, and a visual operative presence is prolonged upon the Bridge. However, the Bridge itself is a prominent and distinctive landscape feature along the Clyde corridor, with works forming part of the existing character of the wider setting.

Upon completion of each works activity, no residual landscape or visual impacts are anticipated, as works are restricted to the already engineered structure, with only minor changes, such as an improved road surface being the only discernible change.

The following mitigation measure will be in place during works:

  • Throughout all works phases, 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.

With the above mitigation measures in place, no significant effects are anticipated upon 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

The works, although confined to the existing structure and not extending into the surrounding landscape, may have potential impacts on the sensitive biodiversity and designated sites within the surrounding area, namely the Inner Clyde SPA, Ramsar site and SSSI. Potential disturbances, such as noise, vibration, and lighting, could disrupt bird species' behaviour, particularly during sensitive wintering periods.

The Bridge spans an area of the Inner Clyde below MHWS and as such, under the Marine (Scotland) Act 2010, a Marine Licence is required for the works. A 10-year Marine Licence was granted on the 18th of December 2024 (MS-00010790).

Following the statutory consultation process, Marine Directorate has undertaken an Appropriate Assessment (AA) due to the potential for the works to have a likely significant effect on the qualifying interest of the sensitive areas located directly beneath the Bridge and works.

This AA concludes that providing the below condition is adhered to, there will be no adverse effect on the qualifying interest of the Inner Clyde SPA, either in isolation or in combination with other projects. This condition, as detailed within the granted Marine Licence is that the licensee must ensure that no lancing activities, which form part of the construction and maintenance works are carried out between mid-September and mid-March. To ensure this condition is being adhered to, regular scheduled programme meetings between Amey’s Environmental Team and the scheme managers are undertaken.

Pollution prevention controls will be implemented as standard to minimise the risk of pollution to watercourses, regardless of European designations. Please see Road Drainage and the Water Environment section below for details.

INNS have been identified within 500m, beneath the Bridge in the surrounding landscape, however as works are contained on the structure, there is no permanent (or temporary) land-take, and there is no requirement to import topsoil, there is limited potential to introduce or spread such species.

The following mitigation measures will be in place:

  • Site operatives will be made aware of the sensitivity of the Inner Clyde SPA, Ramsar site and SSSI prior to any construction activities.
  • Where night-time or winter working is required, directional lighting will be used for all construction activities and aimed away from sensitive ecological receptors including trees and wooded areas at the Bridge’s northern and southern extents.
  • In the unlikely event a protected species is encountered on site, works will be temporarily halted until the animal has moved on, or until Amey’s Environmental Team can provide advice.
  • A ‘soft start’ will be implemented on site during construction activities. This involves switching on plant/vehicles sequentially as opposed to simultaneously, to ensure a gradual increase in noise for minimal disturbance for surrounding biodiversity and protected species.

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

Material assets and waste

Minimising impacts arising from construction materials are focussed upon making the most efficient use of materials on site to reduce the need for imported primary materials and minimise the creation and disposal of waste through reduction, re-use, and recycling.

There is potential for impacts as a result of resource depletion through use and transportation of new materials, for example aggregates. However, recycled, secondary or re-used materials will be used and sourced locally as far as is practicable within design specifications. For example, the binder and base courses used for resurfacing will contain a percentage of recycled material.

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.
  • Any hazardous wastes will be treated as special wastes and be transported by a suitably licenced contractor and will be accompanied by a correctly completed special waste consignment note (SWCN) providing information about the waste source, hazardous properties and disposal/treatment facility. Special waste will be segregated from general waste and other recyclables.
  • 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.
  • All electrical waste, such as that produced during internal electric maintenance works will be disposed of in accordance with the Electrical and Electronic Equipment (WEEE) Regulations.

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 Material Assets and Waste. Therefore, in accordance with DMRB Guidance document LA 110: Material Assets and Waste, no further assessment is required.

Noise and vibration

Construction activities associated with the works have the potential to cause noise and vibration impacts through the use of equipment and construction vehicles for the proposed activities. This will likely impact NSRs beneath and surrounding the Bridge, in particular where noise-heavy works such as blasting are required. Noisy construction activities also have the potential to disturb bird populations of the SPA and Ramsar site located on the riverbanks beneath the Bridge. Please see Biodiversity section above for more details.

Noise surveys were conducted in November 2024 in accordance with British Standard (BS) 7445-1: 2009 +A1: 2014Description and measurement of environmental noise. Part 1: Guide to quantities and procedures to obtain baseline data and noise levels anticipated during the blasting activities. These were undertaken with watching briefs to support the marine licensing process and focused on the identification and level of disturbance of the proposed works affecting the integrity of the sites.

Work activities will be undertaken during both day and night-time working programmes; however contractual agreements are currently in place regarding noise heavy works such as that required for the external painting contract. This includes the following measures:

  • The Best Practicable Means, as defined in Section 72 of the Control of Pollution Act 1974, will be employed at all times to reduce noise to a minimum.
  • The Contractor is responsible for adhering to restrictions as documented by the specification of the contract - Appendix 1/9: Noise and Vibration.
  • All vehicles and mechanical plant used for the purpose of the works will be fitted with effective exhaust silencers which will be maintained in good and efficient working order.
  • Sources of significant noise will be enclosed with acoustic screening. If compressors are used, they will be sound reduced models fitted with properly lined and sealed acoustic covers which will be kept closed whenever the machines are in use and all ancillary pneumatic percussive tools will be fitted with mufflers or silencers of the type recommended by the manufacturers.
  • All machines in intermittent use will be shut down in the intervening periods between work or throttled down to a minimum.
  • Items of plant will be maintained in good and condition so that extraneous noises from mechanical vibration, creaking and squeaking will be reduced to a minimum.
  • Plant, equipment and processes developed for and/or used in the execution of the works will produce the minimum noise commensurate with their required functions.
  • Static machines will be sited as far away as practicable from inhabited buildings.
  • All materials and equipment will at all times be so handled as to minimise noise due to impact.
  • Operatives will receive training to effectively employ techniques to reduce noise.

The Bridge is not located within a CNMA or CQA. Although there are residential receptors in close proximity, and beneath the Bridge and works area, it is expected that the proximity of the Bridge, and railway line to the north suggests that residents within the local area will have a degree of tolerance to noise and disturbance. Following the completion of the works, replaced bridge joints and road surfacing will reduce the noise and vibration currently produced by passing vehicles over the A898 carriageway.

The following additional mitigation measures will be in place:

  • When there is a requirement for night-time working, NSRs within 300m, and the relevant local authorities will be notified ahead of works activities on the Bridge. Pre-notification will include details of proposed timings, works duration and a contact number.
  • Rubber linings will be used in, for example, chutes and dumpers to reduce impact noise.
  • A ‘soft start’ to works will be in place, whereby plant/machinery/vehicles are started sequentially as opposed to simultaneously.
  • A condition as part of the granted marine licence (MS-00010790) is that the licensee must ensure that no lancing activities, which form part of the construction and maintenance works are carried out between mid-September and mid-March.

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

Population and human health

During construction, activities undertaken on site may have temporary adverse impacts on local residents and vehicle travellers as a result of construction presence, and associated noise, and delays where TM will be required for individual work activities. There is potential for temporary adverse impacts on the shared use path (Core Path EI/2) that crosses the Bridge as it may be required to be temporarily closed for specific suites of works. Bus services utilising the Bridge may experience delays during construction periods. No impacts are anticipated on National Cycle Route 7.

The following mitigation measures will be in place:

  • Through access will be maintained at all times on one of the dedicated paths which run along the northbound and southbound sides of the Bridge and accommodate the Core Path EI/2. If access must be restricted, appropriate signage will be in place, at either end of the bridge, to direct travellers along the shared use path on the other side of the Bridge.
  • Appropriate signage and site safety features will be installed with advance notice given to the local communities affected.
  • TM arrangements will be advertised on approach and ahead of each works activity commencing.
  • Non-essential lighting will be switched off at night to minimise visual disturbance to receptors surrounding the Bridge.
  • Appropriate health and safety measures will be considered when working upon the bridge deck to avoid any debris falling on the residential properties, amenity grounds and ecological receptors located below the Bridge.

With best practice mitigation measures in place, no significant effects on 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

During the various work activities, there is potential for temporary impacts on the water environment. Potential changes in water quality from pollution events (either by accidental spillage of fuels or waste material or by mobilisation of these in drainage systems and surface water) during the works could have a direct or indirect effect on the surrounding water environment, in particular the Inner Clyde Estuary and The Forth and Clyde Canal.

This may include paint and dust particles produced from external painting works, however, full containment will be in place for the blasting works to control and capture all debris, dust, and particles generated.

The Bridge spans an area of the Inner Clyde below MHWS as such, under the Marine (Scotland) Act 2010, a Marine Licence is required for the works. A 10-year Marine Licence was granted on the 18th of December 2024 (MS-00010790). Conditions within the licence will be adhered to, with any deviations from the method statement communicated to Amey’s Environmental Team to determine the requirement for a licence variation.

The following mitigation measures will be implemented:

  • To prevent pollution to surface watercourses, there will be appropriate containment and disposal of painting works waste and dust. Please see Material Assets and Waste section for regulatory requirements regarding waste disposal.
  • All operatives will be aware of SEPA’s Guidance for Pollution Prevention (GPP) documents.
  • The Contractor will implement measures to minimise the risk of debris, dust, sediment, and accidental spillages entering the road drainage system. This can be via the use of drain covers or similar to ensure full segregation of the works from the road drainage system.
  • 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/stored:
  • Away (>10m) from watercourses and surface water drainage systems;
  • 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 the mixing of concrete on site is required, site operatives will apply suitable controls to prevent the mixture escaping to the surrounding environment:
  • All mixing will take place a minimum of 10m away from watercourses and drains.
  • All drains within proximity to any mixing will be securely covered or sealed off.
  • No washout from concrete mixing will be allowed to enter the water environment and will be taken off site for appropriate treatment.

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

Climate

Construction activities associated with the works have the potential to cause local air quality impacts as a result of the emission of greenhouse gases (GHGs) through the use of vehicles and machinery, material use and production, and transportation of materials to and from site. However, by undertaking the works the lifespan of the Bridge is increased. This promotes ‘Build Less’ principles outlined within the carbon reduction hierarchy. Furthermore, the execution of timely routine maintenance and repairs to the structure aims to reduce the number of future maintenance interventions and hence this leads to an overall reduction in traffic disruption, construction and material-related carbon emissions.

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, materials movement, and waste will be disposed at a local waste management facility.
  • Further actions, considerations and regulatory requirements for this scheme are detailed in the above Material Assets and Waste

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

Vulnerability of the project to risks

The Bridge is not identified at risk of surface water flooding and there will be no change to the likelihood of flooding on the Bridge as a result of the various works activities. Where cycleway/footway closure is required as part of the works, at least one cycleway/footway will remain open to pedestrians and cyclists throughout the duration of the works.

Works are contained to the existing structure and thus there will be no change in vulnerability of the road to risk, or in severity of major accidents/disasters that would impact on the environment.

Improvement of the road surface following carriageway resurfacing works will enhance skid resistance, and thus overall road safety on completion of the scheme.

TM will be designed in line with existing guidance for each suite of work.

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

Assessment cumulative effects

The works are not anticipated to result in significant environmental effects. Due to the nature of the works, no cumulative effects are anticipated with any other developments in the vicinity.

The West Dunbartonshire and Renfrewshire Council Planning Portals have not identified any extant planning applications within the Bridge surroundings that would result in significant cumulative effects.

The Scottish Road Works Commissioner’s Interactive Map has not highlighted any works programmed to occur on the surrounding carriageways in close proximity to the Bridge.