Description of main environmental impacts and proposed mitigation

Air quality

Construction activities associated with the proposed works have the potential to temporarily cause local air quality impacts. The main sources are likely to be dust generated by the removal and replacement of timber, as well as exhaust emissions from ancillary plant and vehicles. As a result, there is potential for dust, particulate matter, and exhaust emissions to be emitted to the atmosphere. However, taking into account the nature and scale of the works and the following mitigation measures, the risk of significant impacts to air are considered to be low.

Ancillary plant, vehicles and non-road mobile machinery (NRMM) will have been regularly maintained, paying attention to the integrity of exhaust systems.
Ancillary plant, vehicles and NRMM will be switched off when stationary to prevent exhaust emissions (e.g., there will be no idling vehicles).
Cutting, grinding, drilling, coring and sawing equipment (if required) will be fitted or used in conjunction with suitable dust suppression techniques e.g., local exhaust ventilation system that fits directly onto tools.
Regular monitoring (e.g., by engineer or Clerk of Works) will take place when activities generating air pollution are occurring. In the unlikely event that unacceptable levels of air pollution are emanating from the site, the operation will, where practicable, be modified and re-checked to verify that the corrective action has been effective. Actions to be considered include: (a) minimizing cutting and grinding on-site, (b) reducing the operating hours, (c) changing the method of working, etc.
All delivery vehicles carrying material with dust potential will be covered when travelling to or leaving site, preventing the spread of dust beyond the work area.
Material stockpiles will be reduced as far as is reasonably practicable by using a ‘just in time’ delivery system. All material will also be stored on made ground.
Any stockpiled material on site will be monitored daily to ensure no risks of dust emissions exists.
Materials will be removed from site as soon as is practicable.
Good housekeeping will be employed throughout the work.

With the above mitigation measures in place, it is anticipated that any air quality effects associated with the proposed works are unlikely to be significant. This receptor is not considered further in this Record of Determination (RoD).

Cultural heritage

The works will be confined to The A9 Mound Sluices which is covered by a Category A Listed Building designation.

Listed Building Consent (LBC) for the refurbishment works was obtained from the Highland Council in May 2021 (LBC Reference Number: 21/01187/LBC). Refurbishment works commenced in 2021 and the LBC will remain valid until refurbishment works are completed. A variation to the LBC to include works on the apron at arches 4-6 was obtained in September 2023 (LBC Reference Number: 23/01269/LBC). The apron works were conducted in 2025 and no further works related to this variation are required in 2026.

A minor permanent visual change to the structure will occur following the refurbishment works with the replacement of timberworks on arches 3-6. However, works on the Mound Sluices will be in keeping with the character of the structure. The works will preserve and enhance the character and fabric of the structure by using materials and finishes which match the original and are historically accurate. Additionally, the works will aim to prevent any deterioration to the structure and enhance the structure lifecycle. Therefore, no significant residual visual impacts of the works are predicted. In addition, the following mitigation measures will be in implemented throughout the works:

All conditions of the LBC will be met and detailed in the Site Environmental Management Plant (SEMP).
All site personnel will be briefed of the importance of cultural heritage value within the area and advised of the conditions of the LBC and any additional conditions implemented by the Planning Authority or Historic Environment Scotland (HES).
Works will be carried out as detailed in the Design and Heritage Statement produced for the LBC application.
If there are any unexpected archaeological finds, works will stop temporarily in the vicinity, the area will be cordoned off, and a member of the BEAR Environment team will be contacted for advice. Historic Environment Scotland will be contacted as required.
Laydown areas will be sensitively located (e.g., on areas of made ground) to avoid areas of cultural heritage interest where possible.
There will be no storage of plant, materials or equipment against buildings, bridges, walls or fences.

With the above mitigation measures in place, in addition to the LBC already in situ, it is anticipated that any cultural heritage effects associated with the proposed scheme are unlikely to be significant. This receptor is not considered further in this RoD.

Landscape and visual effects

The works are not located in a National Park, National Scenic Area or any other site designated for landscape character and visual effects features.

There will 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 the site compound located in the Highland Council car park. People, ancillary plant, vehicles and materials will be restricted to areas of made/engineered ground off the network access route at the A9 Mound Sluices car park.

As noted above, a minor permanent change will occur following the refurbishment works; however, these will be in keeping with the character of the structure and will not result in a significant visual impact to the surrounding landscape. Similarly, the works will also ensure appropriate measures are taken to ensure the lifecycle of the structure is enhanced.

In addition, the following mitigation measures will be put in place during works:

Works will be carried out as detailed in the Design and Heritage Statement produced for the LBC application.
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.
Works will avoid encroaching on land and areas where work is not required or not permitted. This includes general works, storage of equipment/containers and parking.
The working area and site compound location will be appropriately reinstated following works.
The site will be left clean and tidy following construction

With the above mitigation measures in place, it is anticipated that any landscape and visual effects associated with the proposed works are unlikely to be significant. This receptor is not considered further in this RoD.

Biodiversity

Due to the scheme’s connectivity to numerous European sites, extensive consultation has been carried out with NatureScot over the past several years. Prior to works commencing in 2021, a Statement to Inform Appropriate Assessment (SIAA) was produced and approved by NatureScot which covered the full refurbishment works, including works programmed for 2026. Updates to the proposed works, including the apron works in 2025, and additional consultation with NatureScot were reflected in the updated version of the SIAA in 2022, which concluded that the works were directly connected to the site management of Mound Alderwoods SAC as the restoration of the function of the sluice gates aids in the management of the hydrological regime within this designated site. No Likely Significant Effects (LSE) as a result of the works on the Dornoch Firth and Loch Fleet SPA and Ramsar were identified for the following reasons:

Best practice methods will be used throughout works to prevent pollution and to reduce the impact of noise and lighting (if required) during works.
The works are localised to the Mound Sluices structure and immediate surrounding habitat; therefore, there will be no loss of qualifying habitats or impacts on associated invertebrate and plant species within the sites.
Qualifying bird species in the vicinity of works are likely habituated to existing noise and activity related to recreational activities which take place from the car park and the proposed works are not expected to significantly increase baseline noise levels. Additionally, qualifying bird species will have ample alternative foraging habitat available in the remainder of the SPA/Ramsar site.
There will be no 24-hour working, allowing quiet periods each day for birds to forage undisturbed near to the sluices.

A review of the SIAA carried out in 2026 did not identify any changes to the conclusions of the assessment, as the program of works has not changed from the original works scope (i.e. the full refurbishment of all 12 arches). NatureScot has been consulted regarding works in 2026 and have approved the proposal to condense the refurbishment works due to the poor condition of the arches and concerns that the gates could fail leading to the potential for significant flooding issues upstream.

NatureScot has advised that SSSI consent is not required for the works within Loch Fleet SSSI, as the proposed works are covered by the existing Marine Licence.

There is no requirement for abstraction or discharge into the water environment. As such, there will be no adverse impacts on the Loch Fleet and Dornoch and Cuthill Sands NCO 1995.

There will be no adverse impacts on the Loch Fleet National Nature Reserve as works are restricted to the A9 Mound Sluices bridge and immediate surrounding habitat.

Previous site visits did not identify any INNS, invasive native perennials or injurious weeds within the scheme extent. There is no requirement to import topsoil, and as such, there is limited potential to spread or introduce INNS, invasive native perennials, or injurious flowering plant species.

Pollution controls and good practice measures to reduce impacts of works on the local environment will be detailed in the SEMP and adhered to on site. Any protected species in the area are likely to be accustomed to road noise on the A9, and recreational activities associated with the Highland Council car park and local area. Works are restricted to daytime hours negating requirement for artificial lighting. The following mitigation measures, in addition to any further advised by NatureScot, will be put in place to minimise impacts on biodiversity features in the area:

An Ecological Clerk of Works (ECoW) will monitor and oversee the works on site.
All conditions of the SSSI consent will be adhered to on site.
Pre-construction checks will be conducted in advance of the works.
The main works will be undertaken between June and September inclusive (low flow periods), with the potential for some pre-works/site set-up ahead of this period to facilitate quick start-up of the main in-water works in June.
There will be no working in the water in the months of April-May (inclusive).
The works will avoid wintering bird season (October – March inclusive) as much as possible, with some flexibility for works to run into October if required to complete works as planned (as agreed with NatureScot)
24-hour working will be avoided, leaving a period of ‘quiet time’ each day.
Works will be strictly limited to areas required for access and to carry out the works. Unnecessary encroachment onto terrestrial or aquatic areas out with those previously agreed upon will not be tolerated.
All construction operatives will be briefed through toolbox talks prior to works commencing, which will be included in the SEMP. The toolbox talks will provide information on the legislation, general ecology, and best practice measures for relevant protected species.
Site personnel will remain vigilant for the presence of any protected species throughout the works period. Should a protected species be noted during construction, works will temporarily halt until the species has sufficiently moved on. Any sightings of protected species will be reported to the BEAR Scotland Environmental Team. If required, NatureScot will be contacted for advice.
A ‘soft start’ will be implemented on site each day. This will involve switching on vehicles and checking under/around vehicles and the immediate work area for mammals prior to works commencing to ensure none are present and that there is a gradual increase in noise.
Any excavations, exposed pipes/drains, or areas where an animal could become trapped (e.g. storage containers) will be covered over when not in use, at the end of each shift, and following completion of the works to avoid animals falling in and becoming trapped.
If fencing is utilised at any point during the works, a gap of 200mm from ground level will be provided, allowing free passage for mammals and preventing entrapment.
If an active bird nest is found in vicinity of the works, all works within 30m of the nest will stop until the BEAR Scotland Environment Team can provide advice.
If nesting birds are found during the pre-works check or during works, consultation with NatureScot will be carried out and a licence will be sought if advised by NatureScot. If required, all conditions of any licences will be adhered to.
If required, artificial lighting required for work during low light levels will be directed away from Loch Fleet, road verges, trees, or other suitable habitat as much as is safe and reasonably practicable.

With the above mitigation measures in place, it is anticipated that any biodiversity effects associated with the proposed works are unlikely to be significant. This receptor is not considered further in this RoD.

Geology and soils

The works are not located within a GCRS or geological SSSI and no excavation is required as part of the proposed works. All works are restricted to the A9 Mound Sluices structure and the area immediately surrounding it. However, the following measures will be in place to mitigate any potential adverse impacts on geology and soils:

The parking of machinery/vehicles and storage of equipment on grass will be minimised as far as is reasonably practicable.
Upon completion of the works, any damage to the local landscape will be reinstated as much as is practicable.
Mitigation measures to prevent contamination of soils through loss of containment will be strictly adhered to.
Additional pollution prevention measures as outlined in the ‘Road drainage and the water environment’ section will be adhered to on site.

With the above mitigation measures in place, it is anticipated that any geology and soil effects associated with the proposed works are unlikely to be significant. This receptor is not considered further in this RoD.

Material assets and waste

There is potential for impacts during works as a result of resource depletion through use and transportation of new materials. However, materials will be sourced locally where possible and the following mitigation measures will be put in place:

Materials will be sourced from recycled origins as far as reasonably practicable within design specifications.
Care will be taken to order the correct quantity of required materials to prevent disposal of unused materials.
Where possible, minimal packaging will be requested on required deliveries to reduce unnecessary waste and production of packaging materials.

There is potential for impacts during works are a result of the improper storage or disposal of waste. The following mitigation measures will be put in place:

A Site Waste Management Plan will be completed in line with BEAR procedures.
Any trade effluents will be contained for removal from the site to a licenced waste facility.
The waste hierarchy (Reduce, Reuse, Recycle and Dispose) will be employed throughout the construction works.
All waste stored on site will be adequately protected against the elements.
The subcontractor will adhere to waste management legislation and ensure they comply with their Duty of Care.
Containment measures will be in place to prevent debris or pollutants from entering the surrounding environment.
All wastes and unused materials will be removed from site in a safe and legal manner by a licensed waste carrier upon completion of the works. The appointed waste carrier will have a valid SEPA waste carrier registration, a copy of which will be provided to and retained by BEAR Scotland as early as possible.
All appropriate waste documentation will be present on site and be available for inspection. A copy of the Duty of Care paperwork will be provided and filed appropriately in accordance with the Code of Practice (as made under Section 34 of Environmental Protection Act 1990 as amended).
Re-use and recycling of waste will be encouraged, and the subcontractor will be required to fully outline their plans and provide documentary evidence for waste arising from the works (e.g., waste carrier’s licence, transfer notes, and waste exemption certificates).
Staff will be informed that littering will not be tolerated. Staff will be encouraged to collect any litter seen on site.
Where applicable, all temporary signage will be removed from site on completion of the works.

With the above mitigation measures in place, it is anticipated that any material assets and waste effects associated with the proposed works are unlikely to be significant. This receptor is not considered further in this RoD.

Noise and vibration

Construction activities associated with the proposed scheme have the potential to cause noise and vibration impacts through the use of equipment and construction vehicles for the proposed activities. However, the works are not located within a CNMA or CQA and works will also be conducted utilising a daytime working pattern.

Noise is not likely to be a defining feature of the works based on the proposed working activities and potential to induce worst-case scenario noise and vibration will also be intermittent, temporary and short-lived. The following mitigation measures will be put in place:

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. 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 possible, inherently quiet plant will be selected for construction works.
All site personnel will be fully briefed in advance of works regarding the need to minimise noise during works and of the site-specific sensitivities.
Drop heights from vehicles and NRMM will be kept to a minimum to minimise noise when unloading.
All plant, machinery and vehicles will be switched off when not in use.
All plant will be operated in such a way that minimises noise emissions and will have been maintained regularly to the appropriate standards.
Where fitted, and where permitted under Health and Safety requirements, white noise reversing alarms will be utilised during construction.
Where ancillary plant such as generators are required, they will be positioned so as to cause minimum noise disturbance. Where deemed necessary, acoustic screens will be utilised.

With the above mitigation measures in place, it is anticipated that any noise and vibration effects associated with the proposed works are unlikely to be significant. This receptor is not considered further in this RoD.

Population and human health

During construction, activities undertaken on site have the potential to have temporary adverse impacts on local residents, vehicle travellers and NMUs. TM on the A9 carriageway is not required and local access and NMU/pedestrian movements on the A9 Mound Sluices will be maintained. The Highland Council car park will be used as a site compound which may cause some temporary adverse impacts to visitors of the car park and vehicle travellers who may use it as a rest stop from the A9. It is anticipated that the car park will be closed for the duration of the works following consultation with Highland Council.

There are 3 residential properties in proximity to the scheme, the closest of which (Keeper’s Cottage) is located 20m northeast of the scheme with no visual or acoustic screening present. Therefore, there is potential for disturbance from noise and vibration, however, works will be conducted during daytime hours, and the majority of the works will utilise hand tools only, with no requirement for heavy plant or machinery.

With the following mitigation measures in place, the risk of significant impacts on population and human health is considered to be low:

Works are currently programmed for daytime hours. The works schedule and any changes to this will be communicated to local residents prior to and throughout the programme.
Given the proximity of residential and commercial dwellings to the scheme extent, the Toolbox Talk TTN-042 Being a Good Neighbour will be briefed prior to works commencing.
Appropriate provisions / measures will be implemented within the works area to allow the safe passage of NMUs of all abilities through the site (if required).
Local residents will be notified in advance of the works and in advance of car park restrictions.
Closure of the Highland Council car park will be appropriately signed as required and advance notice of the closure will be provided.

Taking into account the nature and scale of the works and the good site practice measures to be adopted during the works (outlined in the SEMP), it is anticipated that any population and human health effects associated with the works are unlikely to be significant. This receptor is not considered further in this RoD.

Road drainage and the water environment

During the works, there is potential for temporary impacts on the water environment. Potential changes in water quality from pollution events (either by accidental sediments, particulate matter, chemicals, fuels or by mobilisation of these in surface water caused by rain/flooding) during works have the potential to have a direct or indirect effect on the surrounding water bodies.

Due to the works on the coastal section of Loch Fleet (below MHWS) a Marine Licence to permit refurbishment works was obtained from Marine Directorate in 2021 (Licence Number: MS-00009126) and expired in 2025. However, a variation to the marine licence to permit the additional apron works for 2025 was obtained in 2023 (Licence Number: MS-00010220) and is valid until the 31st October 2028, superseding the original licence. The variation permits the planned refurbishment works for 2026. All conditions of the licence and variation will be adhered to on site.

The works will entail in water works on both upstream and downstream sides of the sluices and, as such, will adhere to relevant EASR General Binding Rules (GBRs) for working in or near water, which will be detailed in the SEMP.

The following mitigation measures will be put in place to reduce the risk of pollution incidents as a result of the works:

All conditions of the marine licence and variation will be complied with. A copy of the licence and variation will be present and kept on site for inspection.
Standard working practices to comply with EASR for works in or near water will be detailed in the SEMP and adhered to on site.
No discharges into any watercourses or drainage systems will be permitted.
Appropriate containment measures will be in place to prevent any loss of construction materials into the water environment.
Pollution prevention measures will be checked daily and more regularly during periods of heavy rainfall to ensure they remain effective.
A toolbox talk on silt and sediment containment will be delivered to all site staff as part of the site induction.
An incident response (contingency) plan will be put in place to reduce the risk from pollution incidents or accidental spillages. All necessary containment equipment, including suitable spill kits (for oil and chemicals) will be available on site, quickly accessible if needed, and staff trained in their use.
All spills will be logged and reported. In the event of any spills into the water environment, all works will stop and the incident will be reported to the project manager and the BEAR Scotland Environmental Team. SEPA will be informed of any such incident as soon as possible using the SEPA Pollution Hotline.
All plant and equipment will be regularly inspected for any signs of damage and leaks. A checklist will be present to make sure that the checks have been carried out.
Storage of hazardous material, oil and fuel containers will be distanced more than 10m away from any watercourses.
If required, a designated refuelling area will be identified. Fuel bowsers will be stored on an impermeable area and be fully bunded. This will be distanced more than 10m from any watercourses.
During refuelling of smaller mobile plant, a funnel will be used, and drip trays will be in place. Care will be taken to reduce the chance of spillages. Spill kits will be quickly accessible to capture any spills should they occur. The ground / stone around the site of a spill will be removed, double bagged and taken off site as special waste.
Generators and static plant may have the potential to leak fuel and / or other hydrocarbons and will have bunding with a capacity of 110%. If these are not bunded then drip trays will also be supplied beneath the equipment with a capacity of 110%.
All storage of hazardous materials utilised on site is required to undergo assessment under the Control of Substances Hazardous to Health (COSHH) Regulations 2002. These assessment(s) will contain a section on environment which highlights any precautions and mitigation requirements.

With the above mitigation measures in place, it is anticipated that any road drainage and the water environment effects associated with the proposed works are unlikely to be significant. This receptor is not considered further in this RoD.

Climate

Construction activities associated with the proposed scheme works have the potential to cause local air quality impacts as a result of the emission of greenhouse gases through the use of vehicles and machinery, material use and production, and transportation of materials to and from site. The following mitigation measures will be put in place:

BEAR Scotland will adhere to its Carbon Management Policy.
Local contractors and suppliers will be used as far as practicable to reduce fuel use and greenhouse gas emitted as part of the works.
Where possible, materials will be sourced locally to reduce greenhouse gas emissions associated with materials movement, and waste will be removed to local waste management facilities.

With the above mitigation measures in place, it is anticipated that any climate effects associated with the proposed works are unlikely to be significant. This receptor is not considered further in this RoD.

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