8. ECOLOGY AND NATURE CONSERVATION 8.1. Introduction 8.2. Methods 8.3. Ecological value assessment 8.4. Baseline conditions 8.5. Impact assessment 8.6. Potential impacts 8.7. Mitigation 8.8. Significant residual ecological impacts

8. ECOLOGY AND NATURE CONSERVATION

8.1. Introduction

This section examines how the proposed replacement of the Ba Bridge on the A82 Trunk Road in Rannoch Moor will affect ecology and nature conservation within the vicinity of the scheme (Figure 1, Appendix A). 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 4 – Ecology and Nature Conservation’. The aims of this section are to:

• establish the baseline ecology and nature conservation designations within the vicinity of the scheme footprint;
• assess how the operation of the scheme might affect local ecology and nature conservation;
• detail any mitigation measures taken to counter any possible negative effects on the ecology and nature conservation interests within the vicinity of the scheme, and
• assess the significance of residual effects.

8.1.1. General site description

The A82 Ba Bridge is located in Rannoch Moor, which is an extensive formerly glaciated low-level plateau surrounded by uplands. It is of particular ecological importance due to its range of northern mire types and represents the most extensive complex of western ombrogenous blanket bog and soligenous/valley mire in Britain. The site also contains a range of open water habitats in the form of lochs and lochans.

Rannoch Moor is the only remaining locality for a nationally rare vascular plant species, Rannoch-rush (Scheuchzeria palustris), and contains several other nationally and locally rare species. The study area predominantly comprises wet heath habitat. The habitat is extremely variable, its composition dependant upon the topography of the local area.

The scheme area lies wholly within the Rannoch Moor Site of Special Scientific Interest (SSSI), the Rannoch Moor Special Area of Conservation (SAC) and is immediately adjacent to Loch Ba. Loch Ba is part of the Rannoch Lochs Special Protected Area (SPA) and the River Tay SAC which is designated for Atlantic salmon, three species of lamprey, otter, acid peat-stained lochs and ponds, wet heathland with cross-leaved heath, clear-water lakes or lochs with aquatic vegetation and poor to moderate nutrient levels, and very wet mires often identified by an unstable ‘quaking’ surface. Furthermore, Rannoch Moor has been designated a Ramsar site, a National Nature Reserve (NNR) and a National Scenic Area (NSA) (Figure 3, Appendix A).

The site qualifies as a SAC due to the presence of four habitats that are listed on Annex I of the EC Habitats Directive. In addition, three other Annex I habitats and two Annex II species are present as qualifying features, but not primary reasons for SAC selection (Table 8.1). Further details are provided in Appendix F which also includes the Rannoch Moor SSSI and Rannoch Lochs SPA citations. Rannoch Lochs SPA comprises a cluster of eight oligotrophic lochs. This site qualifies under Article 4.1 of the Directive (79/409/EEC) by supporting populations of European importance of black-throated diver (Gavia arctica), a species listed in Annex I of the EC Habitats Directive.

Table 8.1 Annex I habitats and Annex II species present in Rannoch Moor SAC

Annex I habitat/ Annex II species	Primary reason for SAC site selection
Oligotrophic to mesotrophic standing waters with vegetation of the Littorelletea uniflorae and/or of the Isoëto-Nanojuncetea	Yes
Natural dystrophic lakes and ponds	Yes
Blanket bogs	Yes
Transition mires and quaking bogs	Yes
Northern Atlantic wet heaths with Erica tetralix	No
European dry heaths	No
Depressions on peat substrates of the Rhynchosporion	No
Invertebrate species afforded protection under Annex II of the European Habitats Directive	No
Otter, Lutra lutra	No

The planning guidelines, international commitments, legislation and planning policies relevant to the protection, conservation and enhancement of nature conservation interests in relation to the scheme are given in Appendix G.

8.1.2. Consultation

Scoping was carried out in order to identify the key ecological issues to be addressed in the appraisal. A major part of the scoping included consultations with statutory and non-statutory bodies. Consultees were contacted initially by Jacobs Babtie in 2003, informing them of the details of the proposed development and requesting that they provide any specific baseline information that they may hold or any comments they may have concerning the proposed scheme. A further consultation was conducted by Scotland TranServ in November 2006 to determine if any new environmental issues had developed since the initial consultations by Jacobs Babtie. Details of these consultations in relation to ecology can be found in Sections 5.5.4 and 5.5.11, plus Appendix C, Section 1.2. RSPB were consulted in January 2007 on bird issues, and a final consultation with SNH was undertaken in March 2007 to confirm that the main environmental issues were unchanged.

The main consultees who responded on nature conservation issues were:

• Scottish Natural Heritage (SNH);
• Highland Council;
• National Trust for Scotland (NTS);
• Royal Society for the Protection of Birds (RSPB); and
• Scottish Environment Protection Agency (SEPA).

A search was also undertaken to identify any statutory and non-statutory sites designated for nature conservation value within or adjacent to the site. Evaluation of species and habitats was achieved with reference to European and National designations including local and national Biodiversity Action Plans.

Following the recommendations of these consultations an NVC Habitat Survey, water vole (Arvicola terrestris), otter (Lutra lutra) (see Appendices C and E) and Freshwater Protected Invertebrate) (Confidential Appendix D) surveys were performed.

8.2. Methods

Desk and field based methodologies and mitigation assessments were based on European and UK Nature Conservation legislation and associated best practice guidelines, produced by the Joint Nature Conservation Committee (JNCC), and the DMRB manual, specifically Volume 10 (Environmental Design and Management) and Volume 11, section 3, part 4 (Ecology and Nature conservation)

The National Biodiversity Network Gateway (NBN), http://data.nbn.org.uk/, was searched for records of flora and fauna occurring within the vicinity of Ba Bridge.

An ecological desk study, extended Phase 1 and NVC surveys, as well as species-specific surveys have been undertaken to address the baseline ecological conditions and value of the site, and to identify any opportunity for biodiversity enhancement as a result of the proposed scheme.

Baseline information on the ecology and natural environment within the study area, and in the context of the surrounding landscape, was ascertained through a desktop study and a suite of field surveys to support the Environmental Statement. The field surveys were conducted up to a 500 m radius of the bridge. A full Phase 1 habitat survey (following standard JNCC techniques) was undertaken alongside a more detailed NVC survey and protected species survey on 17th November 2005 by Jacobs Babtie. Follow-up surveys were conducted by Mouchel Parkman (now Mouchel) in August 2007 and Scotland TranServ during June, August and September 2008 (see Appendices D and E).

Although some of the survey work was undertaken over 12 months ago the findings are still considered to be valid and the ecological baseline is unlikely to have changed in this time period.

Baseline conditions of the river habitat have been identified through consultations with statutory consultees, a review of relevant published literature and site visits. Information was also gathered from ecology reports (Jacobs Babtie, 2003) and information on environmental designations in the area of the site. The Scottish Environment Protection Agency (SEPA) reports baseline conditions for watercourses following its current River Classification Scheme.

The methodology used for impact assessment and evaluation adheres to the Institute of Environmental and Ecological Management (IEEM) ‘guidelines for ecological assessment in the United Kingdom’ (2006). This approach involves identifying and evaluating the potential impacts of defined actions on ecosystems or their components recognised or suspected to be present at the site. The assessment of potential ecological impacts pre- and post-mitigation involves an evaluation of the value of each affected ecological receptor (Section 8.3) and an assessment on likelihood of changes/activities occurring and of the significance of potential impacts (Section 8.5).

8.2.1. Habitat Surveys

All areas of semi-natural habitat identified as being of nature conservation importance (local, county, national and international importance), were surveyed in more detail using the National Vegetation Classification (NVC) Phase 2 survey techniques (Rodwell, 1991 et seq). All habitats encountered within 100 m of the existing Ba Bridge were assessed and coded according to the NVC system. Botanical taxonomic nomenclature follows that of Stace (1997) and/or Rodwell (1991 et seq).

8.2.2. Protected Species Surveys

Otter

Otters have full legal protection under the Wildlife and Countryside Act 1981, as amended, and are also protected under the Conservation (Natural Habitats) Regulations 1994, making them a European protected species. As such, it is an offence to intentionally or recklessly kill, take or injure an otter; disturb an otter; destroy, damage or obstruct access to a place of shelter or the shelter itself.

A search of the NBN revealed numerous records of Otter within the same 10km square as Ba Bridge as well as one record within Loch Ba itself.

On the 17th of November 2005, watercourses were systematically searched for signs of otter based on the methodology by Chanin (2003). Signs of otters which were searched for included spraints, footprints, lying-up sites, potential holts or couches, and meal remains (Appendix C).

A follow-up survey on the 11th August 2007 searched the banks of the River Ba within 100m of the bridge, again based on the methodology described in Chanin (2003), paying particular attention to likely sprainting sites such as around the bridge (Appendix E).

Water Vole

In the uplands of Scotland, water voles are often found around watercourses which flow through areas of deep peat with marshy floodplains (Raynor 2005). Water voles are protected under the Wildlife and Countryside Act 1981, as amended, which makes it an offence to damage, destroy or obstruct access to any structure or place which water voles use for shelter or protection. It is also an offence to disturb water voles while they are using such a place.

A search of the NBN showed no records of water vole.

On the 17th of November 2005, watercourses were systematically searched for signs of water vole (Strachan 1998) (Appendix C). Signs of water voles were searched for and these included burrows, runs, footprints, feeding stations, latrines, and faeces.

A further survey for water vole was carried out in conjunction with otter surveys on 11th August 2007, covering all potentially suitable habitats within ~100m of the bridge. The survey was based on the methodology described in Strachan and Moorhouse (2006) and involved detailed searches for field signs such as droppings, latrines, feeding stations, burrows, footprints and runs (Appendix E).

Bats

All UK bat species are listed on Schedule II of the Conservation (Natural Habitats, &c) Regulations 1994 and as such are European protected species. It is illegal to deliberately or recklessly disturb bats (whether in roost or not) or damage, destroy or obstruct bat roosts. The obligation of the agreement on the Conservation of Populations of European Bats (EUROBATS 1994) is to identify and protect shelter and feeding sites that are important for the conservation status of bats.

A search of the NBN showed no bat records in the vicinity of Ba Bridge.

The existing bridge was assessed in terms of its suitability to support bat roosts and a bat survey was undertaken on 11th August 2007 to establish the presence or absence of bats in the survey area. Further details of the Bat survey are given in Appendix E.

Invertebrates

The river is known to support a population of a protected species of freshwater invertebrate. A survey was undertaken in November 2005 by Jacobs Babtie to establish the extent and assess potential impacts on the population with a further survey being conducted by Scotland TranServ environment team in August and September 2008. The results are to be found in Confidential Appendix D.

Other Species

A search of the NBN found records the following species in the same 10km square as Ba Bridge, namely, Black Grouse, Tetrao tetrix, Common Lizard, Zootoca vivipara, Badger, Meles meles, mountain hare, Lepus timidus and Wildcat, Felis sylvestris. However, consultation and subsequent field study did not indicate their presence in the vicinity of the proposed works and thus further consideration is not required.

The nests, eggs and young of all species of wild bird are protected from deliberate damage during the breeding season (March to August inclusive) under the terms of the Wildlife and Countryside Act 1981, as amended. It is best practice to minimise the potential for such damage by removing vegetation likely to be used by breeding birds outside of the breeding season.

The area was also surveyed for signs of reptiles in conjunction with the Phase 1 habitat survey in November 2005. Other key species known to be present but not individually surveyed are included in the evaluation and assessment of the appropriate habitat section. Mitigation for these species is also included.

8.2.3. Limitations

Habitat surveys

Although November is sub-optimal for conducting vegetation surveys with many species in a state of senescence, identification of the key habitat types and dominant species is still possible by experienced botanists. However, it is likely that early-flowering species and annual species may be under-represented in surveys undertaken at this time of year.

Protected Species

Otters are active throughout the year (Chanin 2003b), but the optimum period to carry out surveys is between May and September, when water levels are less variable (Chanin 2003a).

Similarly, the optimum period to carry out water vole surveys is between April and October, when the likelihood of locating breeding territories is highest (Strachan 1998).

8.3. Ecological value assessment

The ‘value’ of an ecological resource (for example a habitat or a species) requires definition within a geographical context. Each feature relevant to the study area is assessed as valuable, or potentially valuable, based on the following geographic frame of reference:

• International; e.g. SPAs, SACs or Ramsar Sites;
• UK;
• National; (i.e. Scotland), e.g. SSSIs;
• Regional; e.g. habitats or species valuable at a regional (i.e. Strathclyde or Tayside) level;
• County; e.g. sites valuable at a county (i.e. Argyll and Bute or Perth and Kinross) level;
• District; e.g. habitats or species populations of value at the district (i.e. Rannoch Moor) level;
• Local; e.g. habitats or species populations of value in a local context (i.e. within ~ 5 km of the scheme extent); and
• Within the immediate zone of influence of the scheme only (i.e. within the working area).

In accordance with IEEM (2006), the value of habitats and species is measured against published selection criteria where available. Reference is also made to UK and local Habitat Action Plans (HAPs) and Species Action Plans (SAPs) (http://www.ukbap.org.uk/) although, as the guidance notes indicate, the inclusion in an HAP or SAP reflects the fact that the habitat or species concerned is in a sub-optimal state and that conservation action is required. Therefore, it does not necessarily imply any specific level of value to the habitat type concerned. Two local Biodiversity Action Plans (LBAPs) cover the Rannoch Moor area. These are the Argyll and Bute LBAP and the Tayside LBAP.

For the purpose of this assessment, the criteria described in Table 8.2 have been used to assess the nature conservation/biodiversity value of the ecological receptors within the study area.

Table 8.2 Evaluation of the Nature Conservation/biodiversity value of ecological receptors.

Value	Criteria	Examples
International	High importance and rarity, international scale and limited potential for substitution	Internationally designated sites (e.g. SACs, SPAs, cSACs, pSPAs, World Heritage Sites). A discrete area which meets the published selection criteria for international designation. A viable area of habitat type listed in Annex 1 of the Habitats Directive, or smaller areas of such habitat which are essential to maintain the viability of a larger whole. Any regularly occurring population of any species that is globally vulnerable (or of more threatened status) as listed by the International Union for the Conservation of Nature. A regularly occurring population of a European Protected Species (as listed on Schedule 2 or 4 of the Habitats Regulations), which is also a UK Red Data Book Species (i.e. listed in one of the UK Red Data Books or in expert update lists). A regularly occurring, nationally significant population/number of any internationally important species.
National	High importance and rarity, national scale, or regional scale with limited potential for substitution	Nationally designated sites, e.g. SSSIs. Regionally important sites with limited potential for substitution. A discrete area which meets the published selection criteria for national designation. A viable area of priority habitat identified in the UK Biodiversity Action Plan (BAP) where the management states that all areas of the particular habitat should be protected, or smaller areas of such habitat which are essential to maintain the viability of a larger whole. Viable areas of key habitat where the need for protection is identified in the Regional BAP/Natural Areas profile of regional value and which have limited potential for substitution, or smaller areas of such habitat which are essential to maintain the viability of the whole. Semi-natural ancient woodland listed on the inventory held by the county statutory conservation agency (the minimum area listing is 2ha). Some smaller areas however, can also be of ‘High’ value. Historic hedgerows that qualify as biologically important under the Hedgerow Regulations (1997). Any regularly occurring population of a nationally or regionally important or scarce species large enough to be considered significant at a county or larger scale.
Regional	High or medium importance and rarity, local or regional scale, and limited potential for substitution	Regionally important sites with potential for substitution. Locally designated sites – Sites of Interest for Nature Conservation (SINCs) and Local Nature Reserves (LNR’s). A viable area of habitat identified in the local or Regional BAP, where it states that all areas of the habitat in question should be protected, (if it has potential for substitution), or is identified as important in this way in the Natural Area Profile. A regularly occurring population of a nationally important species which is not sufficiently large to be considered valuable at county or larger scale. A regularly occurring population of a regionally important species if large enough to be considered significant at the local scale (i.e. between Neighbourhood and District). Any regularly occurring population of a county-important species as identified through e.g. listing in a county "red data book" or BAP, if large enough to be considered significant at this scale.
Local	Low or medium importance and rarity, local scale	Undesignated sites of some local biodiversity interest, including social interest. Viable areas of habitat identified in a sub-County (District/Borough) BAP. Sites/features that are scarce at the sub-County scale or which contribute appreciably to the overall ecological resources at this scale. A diverse and/or ecologically valuable hedgerow network. A viable population of a species listed in the BAP or otherwise judged important at this scale.
Negligible	Very low importance and rarity, local scale	Other sites with little or no local biodiversity interest, including social interest. Plant communities in improved grassland, or well weeded arable land. Isolated species-poor hedgerow fragments. Small areas of non-native planting.

8.4. Baseline conditions

8.4.1. Terrestrial habitats

Semi-improved acid-grassland verges

Along the roadside verges and on either side of the lay-by, located to the north of the existing bridge, are areas of semi-improved acid grassland. The verges most closely resemble NVC community U2 Deschampsia flexuosa grassland. They are generally species poor and somewhat degraded due to grazing and localised pollution effects from road traffic and drainage (Figure 8.1). However, these verges were deemed to provide locally valuable habitat for invertebrates and small mammals and therefore have been attributed Local importance.

Wet-heath habitats

Wetland heath is the dominant habitat in the survey area. It is characteristic of NVC community M15 Scirpus cespitosa – Erica tetralix wet heath with a typical sub-community. This habitat was found to be of varying quality and has suffered from grazing pressure. Some areas are deemed to be of Regional importance (areas west of Ba Bridge) and other areas of National importance (areas east of Ba Bridge).

Figure 8.1 Semi-improved acid grassland verges with many species that would not be locally present without the embankment and road.

Bog habitats

Blanket bog is a protected habitat under Annex I of the European Habitats Directive and is a primary qualifying habitat for the Rannoch Moor SAC site selection. There is an area of bog that is considered to be a transition between NVC community M19 Calluna vulgaris- Eriophorum vaginatum blanket mire, Erica tetralix sub community and M20 Eriophorum vaginatum blanket and raised mire species poor sub community. However, this community has been degraded due to grazing and past burning. Although currently between M19 and M20 there is potential for recovery to the less degraded M19 community. It has therefore been assessed to be of Regional importance.

Other bog habitats present in the study area included NVC community M3 Eriophorum angustifolum bog pools and M25 Molinia caerulea – Potentilla erecta mire, with Erica tetralix sub-community. Within the study area both of these areas were deemed to have Regional importance.

Woodland habitats

There are two small areas of woodland within the study area. The NVC community W4 Betula pubescens – Molinia caerulea woodland with the Sphagnum sub-community is a small area to the south and east of the bridge and will provide suitable habitat for nesting birds. There was also a small area of willow carr which resembles NVC community W1 Salix cinerea – Galium palustre woodland. Both of these habitats were deemed to be important at the Local level.

Aquatic habitats

The open water-bodies in the area are oligotrophic to mesotrophic and contain high quality habitat with vegetation typical of nutrient poor conditions. Loch Ba and Lochan na Stainge are part of the Rannoch lochs SPA. Black Throated Divers (Gavia arctica) attempt to nest on Loch Ba most years but are often unsuccessful due to disturbance from people fishing on the loch (RSPB, consultation response). These water-bodies have been assessed as having value at the International level. The River Ba hosts populations of a protected invertebrate species and is, therefore, deemed to be internationally important. The impact assessment on this species is dealt with in a confidential report written by Jacobs Babtie entitled ‘River Ba Protected Freshwater Invertebrate Report’. A further report produced by Scotland TranServ is also included in appendix D.

8.4.2. Fauna

Invertebrates

The site has been assessed as having International value due to the presence of an internationally rare species of aquatic invertebrate afforded protection under Annex II of the European Habitats Directive and fully protected under schedule V of the Wildlife and Countryside Act (survey results can be found in Confidential Appendix D).

Fish

Atlantic salmon, sea lamprey, river lamprey and brook lamprey are all listed on Annex II of the Habitats Directive, although they are not qualifying features of Rannoch Moor SAC. Suitable salmonid habitat and food resources are likely to be available within the survey area. It was not deemed necessary to undertake detailed fish surveys because the protected invertebrate species is reliant on salmonids as part of its lifecycle and its presence will afford rigorous mitigation measures that will consequently ensure protection of any fish and associated habitats. The fish community of the River Ba, and nearby lochs, is assessed as being of ecological value at the International level.

Reptiles

The habitats within the scheme area provide small extents of largely sub-optimal habitat for common, but protected, reptiles such as viviparous lizard (Lacerta vivipara), adder (Vipera berus) and slow worm (Anguis fragilis), however, no evidence of their presence was recorded in the surveys. Reptiles, if present in study area, would have value at the Local level.

Birds

The presence of the Annex II species black-throated divers that nest on Loch Ba makes the area adjacent to Ba Bridge Internationally important with respect to breeding birds. Birds which may nest in the patches of woodland will be of value at the Local level only.

Mammals

Otters are fully protected under UK and European legislation. Some evidence of otter using this section of the River Ba was found during the survey in August 2007 (Appendix E). One fresh spraint was found immediately south-west of the existing bridge, and its location suggested that individuals may cross the carriageway at this point. There were no holts found during the survey. Otters are common in this part of Highland region and the population within the study area is assessed as forming an integral part of a population which is of value at the Regional level. It is likely that otters will cross the road when travelling along the river as there is no otter ledge in the existing bridge. No evidence of water vole was found within the survey area.

Bats

All bats in the UK are fully protected under UK and European legislation. The existing bridge is assessed as having low potential to support bat roosts due to the nature of its construction, namely, a concrete apron and well-pointed joints. No signs of bats were found during the November 2005 survey. During the survey carried out in August 2007 one bat was observed foraging at dusk, indicating that bats may be roosting nearby and using the watercourse for feeding. The River Ba and nearby lochans are likely to support high densities of airborne insects that will provide prey for foraging and commuting bats. The existing bridge is most likely to be of no value to bats as a roosting site, but the surrounding area is assessed to be of some importance to bats, which are, therefore, attributed value at the Local level.

Other fauna

No other protected, or otherwise notable, species were recorded, and, given the habitats present, none are considered likely to occur within the survey area.

8.5. Impact assessment

8.5.1. Methodology

The ecological features or resources that are of sufficient value to be included in the assessment were determined based on consultation with relevant statutory bodies and conservation groups, the criteria in Section 8.3, and through surveys to establish baseline conditions (Section 8.4).

The development proposals have been compared with the information gathered on the baseline ecology of the site and surroundings in order to predict the potential ecological impacts which are likely to result from the scheme. The evaluation criteria described below have been used to consider whether an impact is ‘significant’, and to assess the significance of residual effects after agreed mitigation measures have been considered.

An ecologically significant impact is defined by IEEM (2006) as ‘an impact (negative or positive) on the integrity of a site or ecosystem and/or the conservation status of habitats and species within a given geographical area’. The assessed value of any feature (Section 8.3) that will be significantly affected is then used to identify the geographical scale at which the impact is significant.

The likelihood that a change/activity will occur as predicted, and also the degree of confidence in the assessment of the significance of the impact must also be considered.

Likelihood is based on a four-point scale as follows:

• Certain/near certain: probability estimated at 95% chance or higher
• Probable: probability estimated above 50% but below 95%
• Unlikely: probability estimated above 5% but less than 50%
• Extremely Unlikely: probability estimated at less than 5%

Significant impacts on features of ecological importance should be mitigated. Any residual impacts remaining, together with the likelihood of success in mitigation, are the factors that would be considered against legislation, policy and development control in determining the application.

8.6. Potential impacts

This section characterises and predicts the potential impacts from construction and operational phases on ecological features in the absence of any mitigation measures.

Widely recognised potential impacts associated with road schemes on nature conservation have been identified in the Design Manual for Roads and Bridges (DMRB) Volume 11, Section 3, (Table 8.3).

Table 8.3 Potential impacts of road schemes.

Impact	Risks	Impacts in the Ba Bridge Study Area
Direct habitat loss	land take	The proposed works involve the replacement of the existing bridge with a bridge at the same location. The permanent loss of habitats associated with the proposed scheme is likely to be minimal in terms of scale and significance and be restricted to the areas adjacent to the existing carriageway. Construction of the temporary bridge and roadway will result in temporary loss of habitat along this route. In addition, a small area of habitat (approx 5 m2) would be lost on the west bank of the river where a support pillar would be required.
Severance or fragmentation of existing habitat areas	smaller areas of land may be more vulnerable to habitat loss, damage or change, and may be unable to support their original number or diversity of species	No additional severance or fragmentation of existing habitat areas is predicted as a result of the proposed scheme, due to the online design of the replacement bridge.
Mortality of animals crossing roads	may cut across their traditional territory or foraging routes	Due to the online design of the replacement bridge, there is not predicted to be a significant change in access level or routing of animals crossing the road.
Hydrological disruption	disruption to drainage pattern or changes in flow and volume of sub-surface water may cause damage to the existing ecology. Resultant impacts can be highly localised or affect habitats some distance away from the scheme	Wetland habitats, including mires, blanket bog and wet heaths are susceptible to impacts from developments that affect the hydrological regimes of those habitats. No permanent impacts will result from the redevelopment due to online design of the replacement bridge. Temporary impacts may result from the construction of a temporary roadway across existing semi-natural habitats to the south west of the existing A82.
Pollution of watercourses	via road drainage, runoff and spray from road traffic	There will be a slight increase in the levels of road run-off as a result of increased area of hard standing. However, because road drainage will now enter the river via a catch pit and swale to the east side of the bridge there will be associated water quality improvements. Traffic levels will not increase as a result of the scheme so the overall level of pollutants will be similar to that which exists currently. During construction, however, run-off of construction materials onto semi-natural habitats may result in adverse impacts to these habitats.
Physical obstructions	caused by road constructions and bridges, particularly to larger animals	No physical obstruction of existing habitat areas is predicted as a result of the proposed scheme, due to the online design of the replacement bridge.
Visual and light pollution caused by road lighting	can affect invertebrates and disorientate birds and mammals	No visual and light pollution impacts are predicted as a result of the proposed scheme, no lighting schemes are proposed in the design of the replacement bridge. During the construction phase use of artificial lighting for night time working has potential to disturb sensitive nocturnal species such as otter and bats.
Air pollution	causes changes in biota and particulates settling on plants can impede photosynthesis	Air pollution is not predicted to be increased during the operation of the replacement bridge. During the construction phase, however, particulate deposition of material arising from construction materials may result in limited impacts close to the construction site.
Disturbance during construction	although construction works are temporary, they can still lead to disturbance and pollution if sufficient care is not taken	Disturbance to habitats in the proposed road corridor and in adjacent habitat areas is likely during construction and due to the presence of temporary bridge construction and temporary site compounds. Visual or noise disturbance to species may take the form of increased human activity, machinery and structures during the construction phase. Disturbance may also occur through physical obstructions in the vicinity during construction, light pollution or air pollution. Watercourses may be temporarily affected by disruptions to drainage patterns or pollution.

8.6.1. Potential impacts on key habitats

Due to the online design of the scheme, the majority of habitat impacts will be associated with the construction phase. There will be no significant change to the local environment through the operation of the completed scheme.

Open and running waters

The nearby lochs and the River Ba are evaluated as being of International importance. There is a possibility of Loch Ba, Lochan na Stainge and River Ba being indirectly affected by construction due to siltation, spray and runoff. Silt causes permanent damage to fish, invertebrates, insects and plants and build up may cause flooding. Water containing silt should never be pumped or allowed to flow directly into a river, stream or surface water drain.

Concrete and cement are very alkaline and corrosive and runoff can have a highly polluting impact on watercourses. A lay-by off the A82, close to the western tip of the loch and north of the bridge, is under consideration for use as the site compound. Such usage as a site compound or for storage of construction material could potentially result in pollution impacts from run-off and road drainage if material were to be deposited close to the loch side.

There would therefore be a probable negative impact on this habitat. Effects may be reversible in time, once construction was complete. Unmitigated, it is rated probable that the habitat could be significantly affected at an international level during the phase of construction work.

It is very unlikely that there will be any significant operational impacts at a national level on standing and running waters as a result of this scheme after construction is complete. The new bridge will be located in the same position as the existing structure and because there will be no net change to the flow or volume of traffic, no increase in associated pollution or run-off is expected. Surface water drainage from the new bridge will be diverted to a catch pit and swale to the East side of the bridge before discharging into the river. Existing in-stream structures are remaining in situ and will support the new bridge so there will be no change in the hydrological regime of the watercourse.

Semi-improved acid grassland verges along the A82

Semi-improved acid grassland is a local value receptor. Part of the verges consisting of this habitat type will be lost due to construction of the temporary bridge. The lower end of the embankments may avoid major habitat loss but suffer disturbance due to construction, and increased pollution as a result of construction activity, drainage and run-off is probable. Unmitigated, a significant impact at this level is unlikely.

There would therefore be a negative impact on this habitat although the magnitude of this effect would be very small. Effects may be reversible in time, once construction was complete. It is considered unlikely that temporary construction impacts could negatively affect the conservation status of the habitat. As a local value receptor, unmitigated, a significant impact at this level is unlikely.

Wet heath habitats

Wet heath is a receptor of Regional to National value. Only a small amount of certain permanent habitat loss through a small increase in hard standing is anticipated as a result of the scheme. A significant impact at Regional to National level is considered unlikely.

However, construction of the temporary bridge would probably result in a more substantial temporary habitat loss in an environment where recovery is slow. Additionally, the habitat may suffer from physical disturbance due to construction and increased pollution as a result of spray and run-off. 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.

Effects may however, be reversible in time, once construction was complete. It is considered that temporary construction impacts could negatively affect the conservation status of the habitat. Unmitigated, a significant impact at Regional to National level is probable.

Mire and blanket bog habitats

Mire habitats are widely distributed through the study area, particularly along the river edge and in undulations among the wet heath. They are valued as receptors of Regional importance. There will be no significant permanent loss of habitat and no increased incidents of pollution resulting from the operational phase of the scheme. A significant impact at Regional level is considered unlikely.

Areas of habitat outwith the construction footprint are unlikely to be directly be affected by the proposed development although again could suffer from disturbance due to construction, and increased pollution as a result of construction activity, drainage, spray, particulate deposition and run-off. 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 probably be negatively affected by pollution events during construction. Unmitigated, a significant impact at Regional level is probable.

Woodland habitats

Woodland habitats are receptors of Local importance. If the construction of the temporary bridge was to take place on the eastern side of the present bridge, the small area of willow carr woodland is near certain to be lost. Unmitigated, a significant impact at local level is considered unlikely.

If the proposed temporary bridge is constructed on the west side of the bridge there would be a very small near certain negative impact upon the willow carr and upon the scattered willow and birch due to pollution during construction from particulate deposition and spray. Unmitigated, a significant impact at local level is considered unlikely.

8.6.2. Potential impacts on key species

As with key habitats, the impacts on fauna will be restricted mainly to construction-related effects. There will be no net change to the local environment, nor any increased adverse impacts to fauna through the operation of the completed scheme. Traffic flows and volume are to remain unchanged (Table 5.3) and so there should be no increased mortality resulting from vehicles. Neither will there be any increased pollution risk or deterioration in water quality as a result of the scheme (Sections 7.5 and 10.12). As such, no adverse impacts are predicted on any fauna.

Otter

Due to their protection by international legislation otters are a receptor of International importance. In general, otters could be disturbed indirectly during the construction phase, and directly through pollution incidents, at any time of the year.

Unmitigated construction work may force otters to exit the water on to the carriageway for the duration of the construction phase, due to the presence of the temporary bridge and associated structures and equipment. This may potentially increase the chances of a fatal collision during this period. Water quality is an important factor for otters, and any soil erosion or increased dust or silt loading during the construction phase may temporarily affect fish prey populations. Pollution incidents in watercourses during construction may adversely affect both fish and otter.

Disturbance may also result during the construction phase due to noise, visual and light pollution around the construction site and site compound.

There would therefore be probable negative impact on otter, although, as the density of the local population is not known, the magnitude of this affect is uncertain. Effects would however, will generally be reversible in time, once construction was complete. On a precautionary basis, it is considered possible that temporary construction impacts could negatively affect the conservation status of the local population. A significant impact at International level is probable. Such an impact would be in breach of law, due to the species’ protection measures.

During operation, there would not be any increase in mortality rates on the carriageway as both road access and traffic levels would not change from current conditions. No physical barriers would be put in place to alter movements. Light levels would also remain the same, and disturbance levels would be unchanged. Any significant impacts are very unlikely.

Bats

In the national surveys of 2005, a significant positive trend in population size was found for field counts in the majority of bat species, although there was a negative trend for colony counts of common pipistrelle¹, the species recorded at Ba Bridge. The UK population for the common pipistrelle is approximately 2.4 million, making it the most common and most widespread species. Scotland’s population has been estimated at between 0.55 and 0.75 million², although there are no regional counts available. There is no evidence however, that the species is particularly rare in the Rannoch Moor area, so bats are considered to be a Local value receptor.

Bats could be disturbed when foraging, or on foraging routes along the watercourse during the construction phase at any time of the year. The temporary bridge and associated structures may create a barrier to regular foraging routes along the watercourse, and adversely affect the ability to capture prey. Any pollution incident or disruption to drainage along watercourses may affect the numbers of insect prey associated with water.

Disturbance may also result during the construction phase due to noise, visual and light pollution around the construction site and site compound during periods of foraging.

There would therefore be a probable small negative impact on bats, although as the local population is not known, the magnitude of this affect is uncertain. Effects would however, generally be reversible in time, once construction was complete. On a precautionary basis, it is considered unlikely that temporary construction impacts could significantly affect the conservation status of the local population. Such an impact would be in breach of law, due to the species’ protection measures.

It is considered very unlikely that there will be any significant operational impacts on bats at Local level as a result of this scheme.

Protected Freshwater Invertebrate

Potential impacts on the Protected Freshwater Invertebrate species are dealt with in Confidential Appendix D, available from Transport Scotland. The invertebrate species is an International value receptor. Unmitigated, it can be assessed that effects from construction are certain/near certain to significantly affect the conservation status of the population at international level. The report by Scotland TranServ in Appendix D shows that the current drainage arrangement appears to be causing a significant impact on the species downstream of the bridge, therefore, unmitigated and with no changes to the drainage, operational impacts are certain/near certain to create a significant impact.

Breeding birds

A response from RSPB in January 2007 stated that they were unaware of any bird species of particular conservation concern in the Ba Bridge vicinity. Species that may breed in nearby habitat are therefore valuable only at local level. Loss of habitat due to tree removal means that there is potential for a negative effect from the operation of the new bridge, although due to small numbers involved and the ability to relocate, a significant affect at local level is unlikely. During construction, disturbance may occur to disrupt breeding. Again however, low numbers involved means that a significant affect at local level is unlikely.

8.6.3. Potential impact on designated areas

Rannoch Moor SAC

There will be no permanent loss of any habitats that are qualifying features of the SAC and so there will be no negative affect on any Annex I habitats. Unmitigated, construction will however have negative impacts on Annex II qualifying species. This means that it is certain/near certain that the proposed development would have an adverse affect on the integrity of the site.

During the operational phase, there will be no net change or increased risk to the SAC as the scheme does not generate and/or redistribute traffic on the A82(T) road. 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. An adverse affect on the integrity of the site from operations is considered very unlikely.

Rannoch Lochs SPA

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 a significant negative impact on both the conservation status at International level of the divers and the integrity of the SPA as a result of the bridge replacement during construction and very unlikely during operation.

Rannoch Moor SSSI

There will be no permanent loss of any habitats that are notified SSSI features during operation, and so it is very unlikely that there will be an adverse impact on the integrity of the Rannoch Moor SSSI from this scheme. The SSSI is cited for its mire habitat, which during construction activities it is rated as probable that this will be significantly affected at this level.

8.6.4. Cumulative impacts

Since there are no other proposed schemes affecting the watercourse at Ba Bridge, the designated sites or within a 30 km radius, no significant cumulative impacts are predicted (see Section 9.5).

8.7. Mitigation

This section details the proposed mitigation measures that will be adopted in order to reduce or prevent potentially significant ecological impacts, as detailed above. This includes measures that have been incorporated at the design stage of the process.

It is important to note that the proposed scheme is a result of an iterative design process and some mitigation measures have been incorporated into its development. For example, the online alignment of the proposed upgrading incorporates mitigation measures to avoid adverse impacts associated with large-scale loss of semi-natural habitats

8.7.1. Design

Alignment

In order to minimise land-take and impacts on surrounding habitats, an online scheme has been selected (i.e. new bridge to be sited in same position as existing bridge). The temporary single-lane bridge that will be used during the construction phase will also be aligned immediately adjacent to the existing bridge in order to minimise land-take and will consist of a single span to avoid the need for any work to be undertaken in the watercourse.

Existing structures

• The use of the existing in-stream piers in the new structure has been selected to minimise the need for any works to be undertaken in the watercourse. In-river working will be restricted to the immediate vicinity of the existing bridge for essential works with no machinery access at this point. No access will be permitted upstream of the bridge in order to safeguard the population of protected freshwater invertebrate species.

Currently otter will have to cross the A82 during high flow therefore, in order to provide environmental benefit, an otter ledge will be incorporated into the design of the new structure..

Drainage

Incorporation of a catch pit and swale, as detailed in the water and drainage section, will significantly improve water quality downstream of the bridge thus providing environmental benefit for the protected freshwater invertebrate, which is currently impacted below the bridge as well as to fish and otter.

8.7.2. Habitat-related mitigation

Permanent loss of habitat will be restricted to small areas immediately adjacent to the existing carriageway. However, additional damage to adjacent habitats will be minimised during construction by adopting best practice construction procedures that limit movements of heavy machinery and restrict access to adjacent areas. In order to avoid significant long-term adverse impacts on the surrounding semi-natural habitat, peatland turf removal, storage and replacement (translocation) strategies will be developed and will include the following steps:

• The turves should be mapped, logged (labelled) and then stored in such order to allow them to be replaced in as close to their original location as possible. To aid this process, photographs should be taken of the site prior to and during the removal of the turfs.
• Turves and blocks should be removed by hand or using a small excavator to maintain the homogeneity and physical structure of the peat and to prevent undue fragmentation.
• Immediately following removal, peat turves and blocks should be kept in storage bags with the vegetated layer on the top and the un-vegetated root matt beneath. Some of the turves can be stored on areas of the existing damaged peat near the lay-by. The blocks should be kept in storage bags until replaced.
• Watering will be required in order to avoid desiccation of the stored peatland material during periods of no rain or of high temperature.
• There is likely to be some shrinkage in the peat blocks, loss of structure and loss of material, so there may be a need to use locally sourced fill at the base of the excavations before peat blocks are placed back. When transplanting the peat blocks they should be packed as tightly as possible (but without compacting the peat) and layered in horizons according to their physical structure to minimise the impact on the sub-surface peat hydrology. The turves should be replaced according to their labelling to recreate the original mire surface.
• Photographs should be taken at this stage to monitor the regeneration of the area.
• Monitoring of the newly translocated peatland areas should be undertaken for a minimum of 3 years.
• No seed mix should be required using this approach – however if seed mix is to be used then no Perennial Ryegrass (Lolium perenne) should be in the mix as this is an alkali-loving plant which will die out over time on the acid-rich substrate leaving a ‘scar’ on the landscape. Any seed mix to be used will comprise species native to the area and of local provenance where possible.

8.7.3. Species-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.

Protected species

It is not anticipated that any protected species will need to be disturbed under licence. However, if the situation arises then appropriate licenses will be sought and monitoring over a prescribed period of time will be undertaken 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 main breeding season (March to August inclusive).

An otter ledge is to be provided in the new scheme which will enable otter to pass safely under the carriageway. The otter population in the area may expand and it is important that otter casualties are minimised. The ledge will be fixed to the existing abutments (which are remaining in situ) at a level above the high water mark. In-river working will be restricted to the immediate vicinity of the existing bridge with no access permitted upstream of this in order to safeguard the population of the protected freshwater invertebrate species.

The population of the protected freshwater invertebrate species will be monitored for at least three years post construction to ascertain if the drainage improvements have had any effect on the population as well as to ensure no damage to the population was caused by construction activities.

8.7.4. Best practice

Particular attention will be given to ensuring that risk of pollution entering the watercourse is kept to a minimum (Chapter 7). Appropriate SEPA pollution prevention guidelines will be adhered to at all times and all materials will be stored appropriately to prevent potential for runoff. 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 will be required to appoint an Experienced Ecologist who will first need to be approved by the Engineer for the Contract. The Contractor’s Experienced Ecologist will be responsible for ensuring that all mitigation and best practice measures are adhered to and should be present onsite at key times of construction.

8.7.5. Timing of works with respect to ecological considerations

Bat, otter and water vole surveys are to be conducted prior to construction.

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 breeding bird season in the UK starts at the end of February until the end of August therefore vegetation clearance and storage could be safely carried out prior to the end of February or at the beginning of September. 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.

8.8. Significant residual ecological impacts

From Sections 8.6.1 to 8.6.3, the likelihood of there being impacts on the conservation status or integrity of each ecological receptor was assessed, resulting in an evaluation of the likelihood that a significant effect would result from either construction or operation of the site.

Following the implementation of the mitigation measures proposed in section 8.7, it is predicted that all potential adverse impacts can be avoided or minimised. In areas where habitats may be subject to probable significant effects prior to mitigation, adoption of the proposed mitigation measures will result in the likely significance of these impacts being reduced from probable to either unlikely or very unlikely.

Table 8.4 Summary of Impacts, and post-mitigation Residual Impacts on Ecological Receptors

Ecological Receptor	Ecological Importance	Significant Impact (construction phase)	Likelihood of significant impact, unmitigated	Mitigation Measures	Residual Significance and confidence level
Loch Ba, Lochan na Stainge and River Ba	International	Pollution of watercourses hydrological disruption	Probable	Online bridge design with otter ledge Use of original in-stream piers Single-span temp. bridge avoids in-water work Crash deck to capture materials before reaching watercourse Turf storage and relocation SEPA Best Practice Guidelines adhered to Surface run-off via catch-pit and swale instead of straight to watercourse Method Statement agreed with SNH The contractor’s ecologist will be responsible for developing method statements and the like.	Unlikely to have a negative affect on conservation status; therefore not significant
Semi-improved acid grassland verges along A82	Local	Habitat Loss Pollution (direct and diffuse) hydrological disruption	Unlikely		Very Unlikely to have a negative affect on conservation status; therefore not significant
Wet Heath Habitats West of the bridge	Regional	Habitat Loss Pollution (direct and diffuse) hydrological disruption	Probable		Unlikely to have a negative affect on conservation status; therefore not significant
Wet Heath Habitats East of the bridge	National	Habitat Loss Pollution (direct and diffuse) hydrological disruption	Probable		Unlikely to have a negative affect on conservation status; therefore not significant
Mire and Blanket Bog Habitats	Regional	Habitat Loss Pollution (direct and diffuse) hydrological disruption	Probable		Unlikely to have a negative affect on conservation status; therefore not significant
Willow carr and scattered trees	Local	Habitat Loss Pollution (direct and diffuse) hydrological disruption	Unlikely		Unlikely to have a negative affect on conservation status; therefore not significant
Otter	International	Habitat Loss Mortality on road Hydrological Disruption Pollution of Watercourses Physical Obstructions Visual and Light Pollution Air Pollution	Probable	Online bridge design with otter ledge Use of original in-stream piers Single-span temp. bridge avoids in-water work Crash deck to capture materials before reaching watercourse Turf storage and relocation SEPA Best Practice Guidelines adhered to Surface run-off via catch pit and swale instead of straight to watercourse Method Statement agreed with SNH Night-time working kept to a minimum Pre-construction monitoring Ecological Clerk of Works	Unlikely to have a negative affect on conservation status; therefore not significant
Bats	Local		Unlikely		Very Unlikely to have a negative affect on conservation status; therefore not significant
Freshwater Invertebrate Species	International	Appendix D	Certain/near certain	Mostly as above but also monitoring pre, during and post construction	Unlikely to have a negative affect on conservation status; therefore not significant
Breeding birds	International	Habitat Loss Disruption during construction	Unlikely	Works to take place outside of breeding season SEPA Best Practice Guidelines adhered to	Very Unlikely to have a negative affect on conservation status; therefore not significant
Rannoch Moor SAC	International	All of above	Certain/near certain	All of above	Unlikely to have a negative affect on conservation status; therefore not significant
Rannoch Lochs SPA	International	Pollution (direct and diffuse) Disruption during construction	Unlikely	Works to take place outside of breeding season SEPA Best Practice Guidelines adhered to	Unlikely to have a negative affect on conservation status; therefore not significant
Rannoch Moor SSSI	National	All of above	Probable	All of above	Unlikely to have a negative affect on conservation status; therefore not significant