10.1. Introduction

This section examines how the construction of the Ba Bridge replacement on the A82 in Rannoch Moor will affect land use, geology and soils, road drainage and the water environment, landscape, cultural heritage, ecology and nature conservation, and pedestrians, others and community effects within the vicinity of the scheme. The study area for consideration of construction effects is 100 m around the footprint of the scheme.

10.2. Methods

This section has been prepared in general accordance with the principles and techniques outlined in ‘The Design Manual for Roads and Bridges (DMRB), Volume 11 (Environmental Assessment), Section 3 Environmental Assessment Techniques, Part 3 – Disruption Due to Construction’. The aims of this section are to: (1) identify possible disruption to the surrounding environment caused by construction associated with the range of activities carried out between the start of pre-construction works and the end of the contract maintenance period; (2) specifically identify the number of properties, and any sensitive ecological and archaeological features within a fluid 100 m perimeter of the scheme; (3) identify construction operations that could have a particularly significant impact and the extent of potential impacts; estimate the likely quantities of surplus material and borrow associated with the scheme; and (5) detail any mitigation measures proposed to counter any possible negative effects associated with construction activities.

Impact significance is determined using the standard four-point assessment system adopted throughout the ES. Baseline conditions for all aspects considered below are discussed in the appropriate Chapters of the report. The assessments were based on a field visit, desk study of relevant plans, maps and documents supported by appropriate consultation.

10.3. Construction processes and methods

The likely range, magnitude and significance of potential effects can be determined through an understanding of the construction process, period and timescales (See Chapter 3). In addition to specific mitigation measures, the potential impacts of the proposed scheme will be managed through the development and implementation of a construction environmental management plan (CEMP). The contractor will be required to produce and implement a CEMP prior to the commencement of work on site and implement all the mitigation measures identified in the Environmental Statement.

10.4. Air quality

The construction phase of the proposed road scheme will contribute to local emissions of dust and air pollutants. The main sources of anticipated impacts on air quality are likely to be dust generated by placement and excavation of materials and other ground disturbance activities, as well as exhaust emissions from equipment and vehicles.

All construction-related emissions will be temporary, vary temporally depending on the type of work being undertaken, and be confined to the site with the exception of vehicles transporting material to and from the site.

Dust is likely to be generated as a result of the following:

  • Site preparation;
  • construction of the temporary bridge;
  • demolition of the existing Ba Bridge;
  • construction of the new Ba Bridge; and
  • landscape restoration works.

At this site, dust will only be a potential impact on the ecology of the area and the local watercourses and water bodies because there are no residents within 5 km of the site.

The contractor will be required to employ proactive working methods to minimise dust creation by ensuring all workers are aware of the possibility for dust nuisance, the conditions likely to result in dust nuisance and the measures required to avoid or minimise dust nuisance.

Mitigation to avoid, minimise and control the generation of airborne dust will be adopted by the Contractor in a Method Statement. This will include:

  • avoiding unnecessary stockpiling of bulk materials that are likely to be subject to wind-blow. Where stockpiling is necessary materials should be covered;
  • placing stockpiled materials away from potentially sensitive receptors, which include areas of peat, vegetation and the River Ba;
  • maintaining site and public roads by providing wheel washes to minimise the accumulation of mud on road surfaces;
  • minimising drop heights during the handling of bulk materials;
  • undertaking regular vehicle maintenance to ensure that emissions of soot and other pollutants in vehicle exhausts are minimised;
  • switching off machinery and vehicles not in use;
  • watering exposed soil surfaces (during drying conditions);
  • covering trucks transporting dust-producing material leaving or entering the construction site; and
  • conforming to all relevant local authority requirements or restrictions for dust generation during construction.

Provided that all of the above mitigation measures are implemented, it is unlikely that there will be any significant dust issues as a result of the construction process.

10.5. Cultural Heritage

Both Highland Council and Historic Scotland have said that there are no known cultural heritage or archaeological interests within the vicinity of the bridge. Furthermore, unrecorded archaeological features are unlikely to be found on site because the area would have been heavily disturbed during the original construction of the A82 and Ba Bridge. A search of the RCAHMS database revealed no cultural heritage interests within the area.

Should unanticipated archaeological artefacts/remains be encountered during construction, they should be dealt with in accordance with procedures set out in ‘Special Requirements in Relation to Historic Scotland’ and agreed with Historic Scotland, Scottish Natural Heritage and the Scottish Executive. A trained archaeologist will be called in if artefacts are believed to have been uncovered.

The assessment of the residual impacts upon cultural heritage during the construction phase of the scheme can be assessed as negligible and insignificant.

10.6. Ecology and Nature Conservation

This section summarises the general ecological impacts on sensitive receptors that may potentially result from the construction of the scheme if mitigation were not to be implemented, and the mitigation required to minimise these impacts.

10.6.1. Potential impacts on key habitats

Open and running waters

There is potential for the watercourse and nearby standing waters to be impacted as a result of siltation and runoff associated with construction and storage of materials. A lay-by off the A82 and to the north of the bridge passes close to the western tip of the loch and is likely to be used as a site compound or for storage of construction material. This could potentially result in pollution impacts from runoff.

The demolition of the existing bridge may result in debris entering the watercourse. This would have a Medium Negative impact upon a habitat with International importance in terms of it supporting a protected species of freshwater invertebrate and as such is assessed as being a potentially Major Adverse impact.

Semi-improved acid grassland verges along the A82

Part of the verges will be lost due to construction of the temporary bridge. This is a Medium Negative impact upon a Local value receptor. Significance of the impact is therefore Minor. The lower end of the embankments should avoid major habitat loss but may suffer disturbance and increased pollution due to construction. This is assessed as a Low Negative impact upon a receptor of Local value. The significance of the impact is therefore assessed as being Minor.

Wet heath habitats

There may be some physical disturbance due to construction and increased pollution as a result of spray and runoff. Furthermore, the riverside areas of wet heath may be subject to pollution events that affect the river, including hydrological disruption and water-borne particulate pollution. This is a Medium Negative impact upon a Regional to Nationally valuable habitat and is considered to be Moderate to Major adverse. Therefore, the overall significance of the potential construction impacts of the proposed scheme on wet heath habitats are assessed as being Moderate to Major.

Mire and blanket bog habitats

Mire habitats are widely distributed through the study area, along the river edge and in undulations among the wet heath. Additionally, as before, the riverside areas of mire may be subject to pollution events that affect the river, including hydrological disruption and water-borne particulate pollution. Although these mire and bog habitats are ombrotrophic, generally relying on atmospheric precipitation rather than surface drainage, they would be potentially affected by pollution events during construction. Therefore, the overall impacts of the proposed scheme are assessed as being of Medium Negative magnitude upon receptors of Regional importance. The significance of the impact on mire and blanket bog habitats is therefore deemed to be of Moderate significance.

Woodland habitats

If the construction of the temporary bridge was to take place on the eastern side of the present bridge, the area of woodland may be lost. This is a Medium Negative impact upon a receptor of Local value resulting in a Minor adverse impact. If the proposed temporary bridge is constructed on the west side of the bridge some willow may be lost and a Low Negative impact upon the scattered willow and birch due to pollution during construction from particulate deposition and spray. This would result in an impact of Minor significance.

10.6.2. Potential impacts on key species


Otters may be disturbed indirectly during construction through noise and obstruction to their free passage, and directly through pollution incidences. These impacts would be High Negative on an Internationally important receptor and, therefore, assessed to be of Major significance. However, no otter holts or resting sites were identified within the footprint of the scheme so it is unlikely that otters will be disturbed or that a licence will be required. Further pre-construction surveys will be undertaken to ensure this is still the case.


There is potential for runoff and pollution associated with construction and storage of materials to enter the watercourse. This could have a High Negative impact on the internationally important protected invertebrate species and is, therefore, assessed to be of Major significance.


It has been confirmed with both SNH and the RSPB that the Black Throated Divers do not nest in the vicinity of the bridge. It is also worthwhile noting that disturbance resulting from fishing has prevented successful breeding in the past. Therefore, it is unlikely that there will be any negative impact on the population as a result of the bridge replacement.

10.6.3. Potential impact on designated areas

Rannoch Moor SAC

There will be no permanent loss of any habitats that are qualifying features of the SAC. With regard to noise, there will be no net change during the operational phase of the scheme due to there being no change in traffic volume; it was for this reason that this element was scoped-out of the assessment.

It is concluded that there will not be a significant effect on the integrity of the SAC from this scheme either during construction or subsequent operation. Therefore, an appropriate assessment is not required under Regulation 48(1) of the Habitats Regulations. This conclusion has been confirmed through consultation with SNH.

Rannoch Moor SSSI

There will be no negative impact on the integrity of the Rannoch Moor SSSI resulting from this scheme either during construction or subsequent operation.

Rannoch Lochs SPA

As mentioned in the section on birds, above, there will be no impact on the Black Throated Diver population and, therefore, the integrity of the SPA will not be affected.

10.6.4. Fauna-related mitigation

Artificial lighting

Night time working will be kept to a minimum in order to prevent disturbance to sensitive nocturnal species such as otter and bat. Any artificial lighting will be very localised, temporary and direct illumination of the River Ba will not occur. Otter fencing will be put in place along the river banks to encourage otters to continue to use the river corridor as a commuting route.

The contractor will be permitted to work within normal construction hours from 0700 hours to 1900 hours during summer months and may be less in winter, seven days a week. If a road closure is required, the work associated with it will take place over night in order to minimise the time required for the closure.

Protected species

It is not anticipated that any protected species will need to be disturbed under licence. However, if the situation arises following pre-construction surveys, then appropriate licenses will be sought by the contractor and monitoring over a prescribed period of time will be undertaken by the ecological specialist and clerk of works to ensure that mitigation works carried out have been successful and that there is no negative impact on the species.

No birds will be disturbed during the breeding season.

Best practice

Particular attention will be given to ensuring that risk of pollution entering the watercourse is kept to a minimum. Appropriate SEPA pollution prevention guidelines will be adhered to at all times and all materials will be stored appropriately to prevent potential for run off. Ground works will be carried out in favourable weather conditions to minimise potential for siltation of the watercourse. It will be a priority to ensure that any works that pose a risk to the watercourse and the protected invertebrate species within are carried out with extreme caution. Any demolition work will be closely monitored to ensure no debris enters the watercourse.

The Contractor’s Experienced Ecologist will be appointed to ensure these best practice measures are adhered to and will be present onsite at key times of construction.

10.6.5. Timing of works with respect to ecological considerations

Bat, otter and water vole surveys are to be conducted prior to construction and the results will be used to determine whether protected species licences will be required.

Vegetation clearance timing is primarily dependent on the breeding bird season. Vegetation clearance here will include removal of some scattered trees to the west of Ba Bridge and also peatland turf translocation. The bird breeding season in the UK begins in March and continues until the end of August. Therefore vegetation clearance will be carried out prior to the end of February or at the beginning of September. No vegetation clearance is to be undertaken during the bird breeding season without first consulting a qualified ecologist.

If site clearance can’t be undertaken outwith the bird breeding season, then all vegetation will first have to be checked for breeding birds before removal. If evidence of breeding birds is found then ground clearance must cease until nests have been vacated.

10.7. Landscape & Visual Effects

The construction impacts that may impact on the landscape and the visual appearance of the area include:

  • erection, operation and removal of site compound with loss of car parking at lay-by due to the contractor’s offices and traffic management;
  • excavation to accommodate reinforced abutments;
  • ground preparation, including crane hard standings, foundation blocks for temporary bridge, construction, operation and removal of temporary bridge, with associated traffic management and signage;
  • storage area;
  • alteration of existing bridge supports and removal of existing Ba Bridge deck;
  • re-construction of replacement bridge; and
  • reinstatement of ground disturbed by temporary works.

Consequently there will be:

  • disturbance to the tranquil character of the area by the presence and activities of major construction plant and workforce;
  • detraction from the scenic beauty of the area;
  • loss of a small area of roadside mire, heath, peat and drift deposits; and
  • potential pollution of the River Ba and Loch Ba, which could result in discolouration of the water and death of aquatic vegetation, both of which will change the visual appearance of the area.

During construction, for travellers on the A82 and from the lay-by approximately 150 metres north of the bridge, where tourists and walkers stop briefly to enjoy the views across Rannoch Moor before continuing north to Glen Coe and beyond, views towards Ba Bridge will be dominated by a construction site, with cabins, cranes, construction materials and a labour force. Further adverse impacts will result from the traffic management required to divert traffic across the temporary bridge, with traffic lights, signage and traffic delays. The magnitude of change is predicted to be high and the temporary adverse visual impact during this phase is anticipated to be severe.

For the infrequent users of the moorland around the bridge, the views to Ba Bridge will be dominated by demolition and construction activities, machinery, materials and personnel. The traffic management associated with use of the temporary bridge and associated traffic lights and traffic delays will also be highly visible and there will also be close views of disturbed ground at the temporary bridge piers and tie-in. The magnitude of change is predicted to be high and the temporary adverse visual impact during this phase is anticipated to be severe.

Distant views of the construction site, temporary bridge, demolition and construction works and traffic management at Ba Bridge will be seen from the West Highland Way. The magnitude of change is predicted to be medium and the temporary adverse visual impact during this phase is anticipated to be substantial/moderate.

In order to minimise potential pollution and unsightliness of the construction process, the following mitigation measures will be adopted:

  • arrest drainage from the site during site clearance, construction and post construction (in accordance with SEPA regulations) in order to ensure that there is no pollution to watercourses, including River Ba/Loch Ba and containment of sediment within surface-water runoff to prevent sediment entering the above water bodies, which may affect the visual appearance of these environmental elements;
  • provision of a crash deck or similar structure to protect the River Ba from construction materials and debris which would cause a visual impact;
  • site compound and works area are to kept in a tidy condition to minimise visual impact;
  • all construction material arising from site clearance works is to be removed from the site and disposed of at an official landfill site or recycled in order to minimise visual impact; and
  • imported materials are to be approved with regard to potential damage at the source of extraction or potential damage to the integrity of the existing site, both visually and ecologically.

10.8. Land Use

There will be a very small amount of peatland/moorland required to site the temporary bridge and works during construction; the exact quantities are as yet unknown. There will be no disturbance to land used by the community or land designated for development.

In order to reduce the construction phase land-use impacts, the Contractor will be required to provide the following mitigation measures:

  • minimise the area of temporary land-take and the duration of its use;
  • re-instate area of temporary land-take to their former land use as soon as possible upon completion of the scheme; and
  • during re-instatement of land, particular care should be taken to minimise disturbance to adjacent habitats to avoid further disturbance to the surrounding land.

Residual construction phase land-use impacts are assessed as neutral.

10.9. Traffic Noise and Vibration

There are no known noise sensitive receptors within the vicinity of the scheme, so no mitigation measures are required. A pre-construction otter survey will be undertaken to ensure that otter Holts or resting sites are not present in the vicinity of the scheme.

10.10. Pedestrians, Cyclists, Equestrians and Community Effects

Disruption to pedestrians and cyclists will be temporary with access restrictions and noise being the main impacts. It is considered extremely unlikely that there will be any impact to equestrians due to the remote nature of the scheme and resulting low use of the area by equestrians. In the unlikely event that equestrians do wish to pass then they should be able to use the temporary bridge. During the construction period it is conceivable that some pedestrian and cyclist’s journeys, within the vicinity of the proposed scheme, will be longer, delayed, obstructed, noisier and subjected to a loss of amenity. The construction process will lower the amenity value of the area from a pedestrian’s perspective and increase the noise from the site over a wider area. Pedestrians and others, if crossing the bridge on the A82, will be proximal to plant, construction activities and motor vehicles whilst passing through the Traffic Management, potentially resulting in increased levels of stress. If these impacts are not adequately managed, potential impacts may cause inconvenience to pedestrians and cyclists. The construction of the bridge and associated scheme will not directly impact on any of the footpaths near the site. However, parking and therefore access may be affected due to site compound location. There is no existing provision for walkers along the A82 road itself, so impacts will not increase during construction and will actually improve because there is increased provision for foot passengers on the temporary bridge. Construction impacts are only expected to be slightly negative given the limited facilities for pedestrians and others at this locality.

Mitigation to reduce any negative effects will include:

  • fencing of works with clear signage to avoid any negative health and safety issues;
  • provision of designated temporary access routes (footways on the temporary bridge); and
  • Sufficient room within the traffic management area to allow cars to pass cyclists safely.

The Mountaineering Council of Scotland expressed concern regarding the impact on visiting walkers and climbers during construction. Any delays will be notified through the Transport Scotland website.

The temporary nature of the impacts and implementation of the mitigation measures mean that the impacts to pedestrians and others during the construction period are considered to only be slightly negative as there will inevitably be some form of delay during construction due to traffic management.

10.11. Vehicle Travellers

Driver views will be affected by the presence of excavation and construction works, temporary accommodation works, earthworks, loss of vegetation, traffic management systems, an increase in signage prior to and within the works area, and the presence of onsite heavy machinery during the construction period. The construction process will unavoidably change traffic conditions and consequently the stress experienced by drivers. An increase in driver stress is likely to be brought about by construction plant accessing and exiting the main carriageway, possible alterations and extensions to journey routes and times, and queuing stationary traffic. The impact, whilst temporary, is likely to adversely affect vehicle drivers to some degree throughout the construction period.

Accommodation of the site compound and materials in the existing lay-bys will result in the loss of parking provision within Rannoch Moor. Furthermore, motorists will experience delays in both directions along this length of the A82. It is not possible to predict the length of delays at this time, but they are likely to be of a short duration. However, there may be periods when longer delays are experienced during peak travel periods. In addition, short closures of between three to ten minutes may be required in order to carry out some safety-critical works.

Mitigation of the impacts will include:

  • not allowing storage areas to exceed the minimum area required;
  • traffic management to maintain continuous traffic flow on the A82;
  • installation of clear, advanced warning signs of the road works;
  • Good maintenance of the construction site and storage areas.

Scotland TranServ will develop a strategy to anticipate and manage emergency vehicles needing access. The contractor will be required to advise police, fire and other emergency response agencies of construction activities, diversions and road closures throughout the construction process. Consideration will also be given to green-period biasing traffic lights based on the north-southbound traffic flow during peak periods, such as bank holidays and the summer season weekends, as well as one-off events attracting large numbers of people.

Even with the adoption of the mitigation measures, the temporary impacts will at worst cause a slightly negative impact to drivers’ views from the road and stress, and the impacts are, therefore, insignificant.

10.12. Road Drainage and the Water Environment

Construction operations have the potential to have direct effects (Table 10.1 and Table 10.2) on site drainage and hydrology with indirect contamination of the nearby watercourses and groundwater due to the:

  • release of site surface water runoff; and
  • Accidental spillage of chemicals, fuels, oils, concrete and other building materials into these watercourses.

Construction activities may result in the release of contaminated sediments, which if not adequately contained might become mobilised, draining into ground or surface waters. Surface-water runoff from the construction site may be high in suspended solids, fuel oils, lubricants and other chemicals used or stored on site. Construction site runoff, with high sediment load that reaches the local watercourses has the potential to adversely affect water quality and may disrupt or damage local aquatic ecosystems.

The stockpiling of soft materials, either excavated during construction or imported, can also be a key issue as they may liquefy during precipitation events, possibly entering ground or surface waters, thus increasing sediment loads.

There is potential for runoff derived from plant/vehicles utilised during the construction period to enter nearby ground or surface waters if not collected. Furthermore, there is a risk of accidental spillage or leakage of fuel/oil from storage tanks or construction plant. Without suitable mitigation measures, these pollutants (suspended solids, hydrocarbons from diesel, petroleum, oil and exhaust emissions, and vehicle-tyre wear deposits) have the potential to enter ground or surface waters.

Measures to reduce the potential effects of the construction activities on water quality will be necessary. The contractor will comply with SEPA Pollution Prevention Guidelines PPG1, PPG2, PPG4, PPG5, PPG6, PPG10, PPG13, PPG22, PPG23 and PPG26. This will be specified within the contract. The Contractor will be required to produce Method Statements for the construction activities to meet the SEPA requirements. The Method Statements will be approved by the Engineer. The Method Statements will detail the construction methodology to mitigate against pollution of surface and ground waters. The requirements will also be included in the Contractors Environmental Management System (EMS) or best practice procedures if the Contractor does not have an EMS, and all employees will strictly adhere to it. When working in close proximity to controlled surface waters, Contractors will be required to comply with the requirements of the Water Environment (Controlled Activities) (Scotland) regulations 2005 (also known as CAR) at all times.

Table 10.1 Generic impacts on the water environment due to construction activities.

Source of Impact

Potential Effects


Accidental release of sewerage from the site compound.

Organic pollution to watercourses, potentially leading to increased biological oxygen demand and low dissolved oxygen, which can cause fish kills.

Oils, Fuels and Chemicals

Spillage from storage tanks or leakage from mobile or stationary plant.

Oils form a film on the water surface resulting in an adverse effect on water quality and ecology. These oils can clog fish gills, cause loss of buoyancy to water birds as well as being toxic to aquatic organisms.

Sediment Loading/Suspended Solids

Suspended solids and coarser sediment in the watercourse can result from excavations, runoff from stockpiles, plant and wheel washing, runoff from site roads, runoff during construction, earthworks and landscaping.

Sedimentation can cause damage to fish, aquatic invertebrates and plants through deposition resulting in a smothering effect or by interference with feeding and respiratory apparatus. Suspended solids may also bind to other contaminants, which can cause pollution of the receiving watercourse.

Concrete, Cement and Admixtures

Accidental release into watercourses of the materials or from the washings of plant and machinery.

Concrete / cement are highly alkaline and must not be allowed to enter any drain or watercourse. Potential for adverse effects on aquatic organisms if pH elevated to/maintained above 8.5.

Table 10.2 Specific impacts to water environment due to construction activities.


Type of Water Resource Impacted

Description of Impact

Batching of Concrete

(If site batching of concrete is required this means that large volumes of aggregate, sand and cement will be imported on the site with the concrete made in situ).

Water Quality

Concrete / cement are highly alkaline and must not be allowed to enter any drain or watercourse. Potential for adverse effects on aquatic organisms if pH elevated to / maintained above 8.5.

Sediment Transport & Fluvial Geomorphology

There is the possibility of fine sediment (silt) getting into the watercourse which can cause discoloration of the water and have a detrimental effect on water quality.

Pouring of Concrete into False work and Curing

Water Quality

The pouring of concrete into false work (temporary structure used to support bridge) can lead to concrete release into the watercourse below. Accidental release of concrete can occur during curing (the process of setting and hardening of concrete).

Sediment Transport & Fluvial Geomorphology

No impact is predicted.

Bridge Demolition

(Demolition of the bridge can introduce large quantities of coarse sediment into river channel.)

Water Quality

Sediments may cause damage to fish, aquatic invertebrates and plants through deposition and consequent smothering or by interference with feeding and respiratory apparatus.

Sediment Transport & Fluvial Geomorphology

Coarse sediment delivery to the river channel may cause bed disturbance and some temporary water discolouration.

Construction of Temporary Bridge

Water Quality

Suspended solids entering channel may also contain contaminants, which can cause pollution of the receiving watercourse.

Sediment Transport & Fluvial Geomorphology

Temporary bridge construction may disturb surrounding slopes and cause slope material to enter the River Ba. This may cause some localised deposition.

Construction of New Bridge

Water Quality

There is the possibility of sediment reaching the river channel during construction of the new bridge, with the same impacts as discussed above.

Sediment Transport & Fluvial Geomorphology

Slope material may enter the watercourse.

More specifically, the Contractor will minimise potential pollution at source by adopting all of the following measures:

  • scheduling construction activities so that the area and duration of soil exposure are minimised to that required for practical completion of the works;
  • where possible, undertaking construction in phases so that sections are restored before progressing to the next section/phase;
  • minimising the movement of construction plant and equipment on site;
  • locating stockpiled material away from existing watercourses;
  • containment of runoff prior to treatment and disposal;
  • provision of wheel washes where appropriate to reduce transfer of sediment;
  • adopting pollution prevention procedures at all times;
  • no abstraction of water from or disposal of water into any watercourses; and
  • Work at the edge of a watercourse will be minimised and, if necessary, a CAR licence will be sought otherwise CAR General Binding Rules to be followed.
  • Silt traps to be used and maintained at all times throughout the duration of the works to prevent sediment entering the watercourse.

The construction site surface-water runoff will require removal and/or sediment/pollutant removal by the incorporation of appropriate containment and drainage mechanisms. These will be covered by PPGs 5 and 6 and within the required Method Statement.

Additional measures to be taken by the Contractor to minimise spillages from stored materials such as oils, fuels and chemicals include:

  • storing these materials in bunded areas at the standard requirement of 110% containment capacity of the volume stored;
  • spillage trays will be fitted to any stationary construction plant;
  • any water resulting from washing out/cleaning plant and equipment will be contained and the sediments will be allowed to settle before being suitably disposed; and
  • Any waste materials will be stored in designated areas and removed from the site in accordance with the Duty of Care principles. Again, these measures will be covered within relevant Method Statements.
  • Excavated or imported soil will be stockpiled in a location away from watercourses. The stockpile area will be bunded to provide an impermeable barrier to the potential migration of pollutants into nearby water bodies. It may be necessary to cover stockpiles in times of particularly poor weather to minimise migration of particles.
  • Any concrete will be mixed away from areas close to watercourses or locations where infiltration of water into the ground is possible. Ideally, the concrete will be mixed off site and delivered to the site. When conducting concrete works in or close to watercourses, an impermeable barrier will be necessary to prevent transport of cement particles to the watercourse. Mitigation measures for the specific impacts of the scheme are detailed in table 10.3

Table 10.3 Water environment mitigation measures for the construction phase for specific impacts.


Mitigation Measure

Batching of concrete

Measures must be taken to ensure that in situ concrete is placed accurately within a sealed off area and that concrete pumps including their wash-down do not discharge into the river. Measures must also be taken to prevent fine sediment entering watercourses through, for example, the use of temporary sheeting over exposed piles of sand and aggregate.

Pouring of concrete into false work and curing

To prevent concrete entering watercourse during the pouring of concrete into false work, a secondary layer of false work below the primary layer will be employed. This will act as a false bottom to intercept any concrete falling from above. This will remain in place until the concrete has set and hardened (curing process). The additional measure of a plastic sleeve around the area of works will be employed.

Bridge demolition

In order to minimise the impact of demolition on the river channel, all debris from the bridge must be removed from the site and care must be taken to ensure this material does not enter the river channel. Prior to any demolition work, an approved crash deck or similar structure must be provided in the adjacent area to protect the watercourse from falling debris and other waste arising. In order to prevent excessive dust and debris, the deck shall be removed by the formation of a number of fragments formed by stitch drilling/coring from above with dust removal by vacuum.

Construction of the temporary and new bridge

Slope disturbance will be kept to a minimum. Unconsolidated material that could be disturbed will be removed or stabilised by fine netting prior to vehicle access and construction. Sediment fencing must be placed at the bottom of the slope to trap any bank material that is washed out.

Finally, SEPA provide guidance and advice on pollution incident response planning in document PPG21. This guidance will be adhered to by the Contractor and included in the preparation of the Method Statement detailing the emergency procedures that will be undertaken should a pollution event occur. This will be specified within the EMS or best practice procedures written by the Contractor, and will be specified within the contract.

Assuming that the mitigation measures are implemented, the residual impact in terms of magnitude will be low and significance will be slight to negligible. Furthermore, with effective mitigation the risk of sediment release during construction will be reduced, therefore, the significance of the impact will be neutral. Notwithstanding the implementation of mitigation measures described above, some delivery of fine sediment to the river channel is likely to be unavoidable. Some temporary water discolouration during demolition and construction is also likely to occur, however, small volumes of fine sediment released are unlikely to have a significant impact on the fluvial geomorphology of the river channel. If the mitigation measures are implemented this should prevent large volumes of sediment being supplied to the river channel. As such, the residual impact for sediment transport and fluvial geomorphology is predicted to be neutral.

10.13. Geology and Soils

Geology will remain unaffected by the construction processes. Geomorphological processes and soils will be affected by construction activities in a number of ways. Peat and drift deposits will be excavated with some being permanently removed or used for landscaping works. In disturbed areas, exposed soil is liable to erosion by fluvial and Aeolian action. The movement of construction staff around the site may lead to local compaction of soil affecting its surface and subsurface hydrology, making it more liable to water logging, poaching, and erosion, because water will accumulate on the surface, and potentially lead to localised but intensive erosion where there is sufficient slope for the water to run off. There could potentially be some contamination of soils and minerogenic substrates from construction activities.

The potential loss of a small area of peat and minor disruption to two hummocky moraines means that the construction impact on geomorphology and soils can be assessed as slightly negative.

Disturbance to the geomorphological and soil attributes of the study area will be minimised through the adoption of the following mitigation measures:

  • limitation of the extent and location of working and storage areas to non-sensitive areas;
  • implementation of erosion and sediment controls;
  • use of geotextiles to armour bare ground susceptible to erosion;
  • minimise the risk of Aeolian erosion by regularly wetting bare areas of ground and erecting wind breaks;
  • try to minimise steep, exposed and bare slopes that are susceptible to erosion;
  • temporarily cut and remove peat (Chapter 8) and underlying glacial till where temporary features are to be erected;
  • minimise compaction of soil by constructing suitable pathways for construction staff to travel along;
  • appropriate handling and storage of wastes, chemicals and other materials;
  • any exposed cuttings within the moraines will be graded so that the minerogenic material lies at an angle several degrees below the angle of repose for sandy substrate;
  • reuse of excavated materials in the construction of embankments and landscaping where possible; and
  • Reinstatement of substrate and soils on completion of the works. These materials will be stored in a suitably cool, well lit (though not direct sunlight) and moist environment.

Residual impacts are assessed as negligible because much of the soil and substrate will be reinstated, and that which is not reinstated will be used for the construction of the wider embankments.

10.14. Health and Safety

The Health and Safety Executive states that the Health and Safety at Work Act 1974 should not be compromised during construction. Best construction management practices will be in place to ensure the safety of construction workers during construction of the scheme. Fencing and lighting of construction works, recognised safety practices for the utilisation of heavy equipment and the movement of construction materials will be implemented to avoid accidents. During construction, the project contractor will be responsible for job-site safety and security. Diversions, lane closures and vehicle entrance locations will be well signed and managed appropriately to minimise disruption.

10.15. Storage of materials and waste, and site location

The following measures will be followed to ensure minimal disturbance and pollution from the site works as well as those already described throughout this report:

  • Re-use and recovery of the material arising from the bridge demolition in preference to disposal;
  • The site operators will adhere to all waste management licensing requirements; and
  • If the compounds require lighting and provision of utilities, including water, foul drainage/septic tanks and electricity, the site operators will make the necessary arrangements with local landowners and comply with the relevant regulatory authority requirements for this purpose. It will be important to ensure that no areas are used that could significantly adversely impact on sites or features identified within this ES as requiring protection.

10.16. Summary of construction impacts

Impacts caused during the construction phase of the proposed scheme are typically short-term or temporary in nature. When coupled with the implementation of mitigation measures specified in the contract and the development of a construction environmental management plan (CEMP) by the Contractor prior to commencement of works on site, many of these impacts are predicted to be avoided or reduced. As such, residual construction phase impacts are assessed as being slight to moderately negative, at worst.

To further reduce any potentially significant adverse impacts, management of the construction phase by the Contractor will be undertaken in accordance with the requirements of the Scottish Government, Scottish Natural Heritage and the Scottish Environment Protection Agency.