Scottish Government: Business, Enterprise & Energy Directorate
Appraisal of the Implications of the proposed Beauly to Denny transmission line development on the River Tay Special Area of
Conservation (SAC)
2009
The following appraisal has been prepared by the Scottish Ministers as the Competent Authority for the above proposal.
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Project and site description
Brief description of the project
Scottish and Southern Energy (SSE) and Scottish Power (SP) submitted applications to
Scottish Ministers (under section 37 of the Electricity Act 1989) proposing an upgrade of
the main electricity transmission line from the Highlands to the Central Belt. The proposal
is to replace the existing 132kV line from the Beauly substation near Inverness to
Bonnybridge in Stirlingshire with a 400kV line from Beauly to Denny, near Falkirk.
The proposal includes the following:
220km of new double circuit 400kV overhead transmission line on steel lattice
towers from Beauly substation to a new substation near Denny via Fasnakyle.
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Development of new or existing substations at Beauly, Fasnakyle, Fort Augustus,
Tummel and Braco substations.
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Removal of all the existing 132kV overhead transmission line.
The purpose of the project is to provide the transmission infrastructure to enable new
generators in the north and west of Scotland, to link to centres of demand further south
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Brief description of the designated Natura
site
The River Tay supports a high-quality Atlantic salmon population; the Tay drains a very
large catchment and has the greatest flow of all UK rivers. There is considerable
ecological variety in the Tay catchment, resulting in the Tay supporting the full range of
salmon life-history types found in Scotland, with adult salmon entering the Tay throughout
the year to spawn in different parts of the catchment.
The River Tay is a SAC due to the presence of the following qualifying species and
habitats:
 Atlantic salmon;
 river lamprey;
 sea lamprey;
 brook lamprey;
 otter; and
 oligotrophic to mesotrophic standing waters with vegetation of Littorelletea uniflorae
and/or isoeto-Nanojuncetea, commonly referred to as clearwater lakes or lochs with
aquatic vegetation and poor to moderate nutrient levels.
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Conservation objectives for the designated Conservation objectives of the River Tay SAC species interests are:
Natura site
To avoid deterioration of the habitats of the qualifying species and habitats (listed above)
or significant disturbance to the qualifying species, thus ensuring that the integrity of the
site is maintained and the site makes an appropriate contribution to achieving favourable
conservation status for each of the qualifying features.
To ensure for the qualifying species that the following are maintained in the long term:
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population of the species, including range of genetic types for salmon, as a viable
component of the site
distribution of the species within site
distribution and extent of habitats supporting the species
structure, function and supporting processes of habitats supporting the species
no significant disturbance of the species
To ensure for the qualifying habitat that the following are maintained in the long term:
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Extent of the habitat on site
Distribution of the habitat within site
Structure and function of the habitat
Processes supporting the habitat
Distribution of typical species of the habitat
Viability of typical species as components of the habitat
No significant disturbance of typical species of the habitat
Screening
Is the proposal directly connected with, or The proposal is not directly connected with, or necessary to, the conservation management
necessary to, conservation management of the of the River Tay SAC and therefore further consideration is needed.
designated Natura site?
Consider whether there are any likely direct, The proposed 400kV transmission line would cross the Errochty Water at one point
indirect or secondary impacts of the project (however the existing 132kV line also crosses the Errochty Water at one point). Upgrades
on the designated Natura site
of existing tracks would be undertaken on both sides of the Errochty Water; no access
tracks would cross the water.
The 400kV line would also cross the River Tummel at one point whereas the existing
132kV line crosses the Tummel at three points. Upgrades of existing access tracks would
be undertaken on both sides of the Tummel, these would be used for access for the
construction of the 400kV transmission line and the dismantling of the existing 132kV line.
No access tracks would cross the Tummel.
The proposed 400kV line would cross the Tay at one point and run parallel to the SAC
from the B846 near Tirinie to the A827. Upgrades of existing tracks and the provision of
new access tracks would be undertaken on both sides of the river Tay. These would be used
for access for the construction of the 400kV line and the dismantling of the 132kV line. No
access tracks would cross the Tay.
The proposed 400kV line would cross the River Almond at one point and a short section of
new access track would be required to the North of the Almond.
The potential impacts of the proposal are:
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Potential for increased watercourse sedimentation within SAC during construction
phase. This could have a significant impact upon salmon and lamprey spawning
beds and/or the gills of salmon juvenile being smothered and/or also their
movements impeded.
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There is also a possible risk of contamination of the watercourse from the fuel and
chemical spillages/leaks. Any loss of water quality could adversely affect the
salmon and lamprey interests, which would in turn affect the otter population which
feeds on them.
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Potential risk of desertion of the territory by all qualifying species during
construction through displacement or disturbance, such as noise and vibration from
heavy machinery, earth movement, the preparation of foundations and
loading/unloading of machinery. This would constitute a significant disturbance.
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There is also a possible risk of sedimentation and/or contamination of the
Clearwater lochs from fuel and chemical spillages/leaks, however given the lack of
proximity of the development to Clearwater lochs within the SAC, this impact is
unlikely.
Consider the key phases of development and During all phases of the development, but particularly during the construction and
the risk of effects associated with each.
dismantling phases, a key consideration is pollution which may have a direct toxic effect
on the aquatic protected species and their food source, as well as a degradation of their
habitats. Pollution can also take the form of silt laden run-off. This may also have direct
effects on species, such as inhibiting of respiration through affecting gill function. Silt also
affects the habitats of aquatic protected species, such as the infill of salmon redds and
lamprey spawning grounds. Siltation may also result in increases nutrient status, leading to
the eutrophication of the aquatic protected species’ habitat.
During the operation phase, risks are less because there will be less activity on site, but
accidental spillages from vehicles or storage areas are still possible and could affect the
SAC as described above.
Construction
Construction activities give rise to the risk of direct loss or and/or disturbance of habitats,
disruption to otter travelling routes, pollution and sedimentation of watercourses and
impacts upon channel management.
Operation
The operation phase of the development carries less risk of effects on the specified interests
than the construction phase, due largely to routine maintenance activities.
Dismantling
Dismantling of the existing 132 kV line gives rise to the risk of effects similar to those
associated with the construction of the proposed line, including direct loss and/or
disturbance to habitats, pollution, increased sedimentation etc.
Dismantling of the proposed 400 kV line gives rise to the risk of impacts which are
currently hard to assess given the expected ‘lifespan’ of the line being c. 80 years. Any
risks associated with this dismantling process are likely to be similar to those associated
with the construction phase of the development, and mitigation measures would be
required to ensure any impact on the SAC is minimised.
The potential impacts on Clearwater lochs would only likely arise from construction and
dismantling phases, and as described above would include loss of habitat and pollution and
sedimentation of the water body.
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Appraise which individual elements of the The elements of the proposal which will give rise to the greatest risk of effects are the
overall project would give rise to the greatest construction phase, the operational phase and the dismantling and removal of the 132kV
risk of effects. State any element of the line.
project where the scale or magnitude of effect
is not known
Construction phase
Construction of transmission line tower bases and towers – The proposed 400kV
transmission line route would be within the catchment area of the River Tay system from
the Drumochter Pass to south of Muthill in Perthshire. Construction sites for tower bases
and towers of varying distances from the River Tay and associated tributaries would,
therefore, be required through this area.
Construction of borrow pits – Construction of borrow pits would be required throughout
the River Tay catchment area.
Access track construction – Track upgrades and construction would be undertaken
throughout the length of the transmission line route.
Crossing of waterbodies/watercourses – Fording of waterbodies/watercourses by vehicles
and plant will not be permitted through the entire working corridor of the proposed 400kV
line. Where the crossing of a waterbody/watercourse associated with the River Tay
catchment is unavoidable, bridges will be used in preference to culverts.
Tree felling – Tree felling would be required to be undertaken for the overhead corridor
and access tracks for the proposed 400kV transmission line within the catchment area of
the River Tay SAC. Tree felling would be required within areas of commercial plantation
forestry at Glen Errochty, to the north and south of the proposed crossing point at Tummel
and to the south of Appin of Dull.
Operational phase
Routine maintenance would involve inspection of each tower and conductors
approximately every 5-6 years to assess the requirement for remedial works. Maintenance
could result in general pollution and siltation.
Dismantling 132kV line
Removal of transmission line tower bases and towers – The existing line runs from the
Drumochter pass to south of Muthill within the Tay catchment. Sites for the dismantling of
tower bases and towers of varying distances from the river Tay and associated tributaries
would, therefore, be required throughout this area, including six water crossings.
De-stringing of transmission lines – the technique of de-stringing lines uses a method
called catenary Support System (CSS) which would ensure that conductors are not pulled
through waterbodies/watercourses.
Borrow pits – potential impacts associated with the construction of borrow pits in the
dismantling phase would be consistent with those associated with the construction phase.
Access track construction – Similarly, the construction of access tracks required for the
dismantling phase would have potential impacts like those associated with the construction
phase.
Crossing of waterbodies/watercourses – Same as in construction phase.
Tree felling – the potential impacts associated with tree felling on aquatic protected
species, namely increased flows, siltation and acidification.
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Is the plan/project likely to have a significant
effect on the River Tay Special Area of
Conservation, either alone or in combination,
with other plans or projects?
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Lamprey species: likely significant effect. The proposed overhead line passes over
the River Tay SAC and the wider River Tay catchment giving rise to potential
impacts upon lamprey species from pollution, sedimentation, disturbance and
habitat loss.
Clearwater lochs: no likely significant effect. Within the SAC, the development
will only cross the main stem of the River Tay and three of its tributaries, not any
Clearwater lochs. Given this lack of proximity to such lochs, the development is
assumed not to have a likely significant effect.
Otter: Likely significant effect. The four watercourses (Errochty Water, River
Tummel, River Tay and River Almond) all show good levels of otter activity
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including a number of holt sites. The Errochty and Almond provide the most
optimal habitat in terms of undisturbed wooded riverine habitat with boulder fields
providing excellent actual, and potential for, resting up sites
Atlantic salmon: likely significant effect. The proposed overhead line passes over
the River Tay SAC and the wider River Tay catchment giving rise to potential
impacts upon salmon from pollution, sedimentation, disturbance and habitat loss.
Appraisal of Impacts on Site Integrity
Identify the relevant conservation objectives The conservation objectives to consider are those that relate to the qualifying species and
to consider for the designated Natura site.
which may be affected by the proposal. These are:
To avoid deterioration of the habitats of the qualifying species (listed above) or significant
disturbance to the qualifying species, thus ensuring that the integrity of the site is
maintained and the site makes an appropriate contribution to achieving favourable
conservation status for each of the qualifying features; and
To ensure for the qualifying species that the following are maintained in the long term:
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population of the species, including range of genetic types for salmon and lamprey,
as a viable component of the site
distribution of the species within site
distribution and extent of habitats supporting the species
structure, function and supporting processes of habitats supporting the species
no significant disturbance of the species, and
10 Can it be ascertained that the proposal/plan Atlantic Salmon:
will not adversely affect the integrity of the
River Tay SAC?
For the conservation objectives for Atlantic Salmon the following assessment can be made:
To avoid deterioration of the habitats of the qualifying species (listed above) or significant
disturbance to the qualifying species, thus ensuring that the integrity of the site is
maintained and the site makes an appropriate contribution to achieving favourable
conservation status for each of the qualifying features – as described below, the habitats of
the salmon interest could potentially be affected by pollution and/or sedimentation and this
in turn would have an impact on salmon
To ensure for the qualifying species that the following are maintained in the short term:
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population of the species, including range of genetic types for salmon, as a viable
component of the site - The population and its genetic component could be affected
by impacts on spawning beds or juvenile salmon gills being smothered and/or
movements being impeded as a result of construction traffic, increased
sedimentation or pollution during construction activities or routine maintenance
works.
distribution of the species within site – The loss of Atlantic salmon in the SAC by
contamination of watercourses by pollution during refuelling activities or chemical
works, or increased sedimentation from traffic during construction or dismantling
may reduce the occupation of the SAC, and hence the distribution within the SAC.
distribution and extent of habitats supporting the species - The proposal crosses the
SAC and pollution may affect the quality of the water and consequently the habitats
of the SAC.
structure, function and supporting processes of habitats supporting the species –
As above, the proposal crosses the SAC and so any pollution incidents may affect
the structure, function and supporting processes of the habitats of Atlantic salmon
in the SAC.
no significant disturbance of the species – . A significant pollution event or noise
and vibration from construction and dismantling activities could constitute
significant disturbance to Atlantic salmon within the SAC. If the disturbance
resulted in salmon becoming absent from sections of the SAC, this would constitute
significant disturbance.
Lamprey species
For the conservation objectives for River, Brook and Sea Lamprey the following
assessment can be made.
To avoid deterioration of the habitats of the qualifying species (listed above) or significant
disturbance to the qualifying species, thus ensuring that the integrity of the site is
maintained and the site makes an appropriate contribution to achieving favourable
conservation status for each of the qualifying features – as with salmon, the habitats of the
lamprey interest could potentially be affected by pollution and/or sedimentation.
To ensure for the qualifying species that the following are maintained in the short term:
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population of the species, including range of genetic types for salmon, as a viable
component of the site - All lamprey species have a similar population lifecycle with
juvenile lampreys living in silt beds in slower-flowing reaches of the river.
However the river and sea lamprey (like salmon) migrate to the sea to feed before
returning to spawn in the River Tay. Brook lamprey remain in freshwater all their
lives. The populations of lampreys in the Tay could be affected by impacts on
spawning habitat and/or the migration of lampreys being impeded,
distribution of the species within site – Areas of poor water quality can sometimes
create a barrier to migration preventing River and Sea lampreys in particular from
reaching their spawning grounds. The Brook lamprey remains within the river and
can be far more widely distributed across a catchment, and populations can be
found upstream from obstacles that prevent access for the other two species.
Adverse water quality, which could result from such activities as described above,
has the potential to affect all three species.
distribution and extent of habitats supporting the species - Lampreys require two
very different types of habitat during their life cycle. The adults breed in pits
excavated in gravel beds, often near the tail of a pool, during the spring or summer.
The gravel should be clean and in faster-flowing reaches where the eggs can be
supplied with oxygen. The juveniles have very different habitat requirements and
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live buried in silt beds, usually at the rivers edge or in other slower flowing reaches.
Increased suspended solids can smother spawning gravels and may affect silt beds
containing juveniles.
structure, function and supporting processes of habitats supporting the species –
possible effect. Lampreys require well oxygenated water that is low in nutrients
and suspended solids. As above, increased suspended solids can smother spawning
gravels and silt beds containing juveniles.
no significant disturbance of the species – Lampreys are susceptible to disturbance at
any stage of their life cycle. After spawning, the eggs can be disturbed during
incubation and the juveniles are also vulnerable to disturbance. A significant pollution
event or noise and vibration from construction and dismantling activities could
constitute significant disturbance to lampreys within the SAC. If the disturbance
resulted in lamprey becoming absent from sections of the SAC, this would constitute
significant disturbance.
Otter
For the conservation objectives for otter the following assessment can be made:
To avoid deterioration of the habitats of the qualifying species or significant disturbance to
the qualifying species, thus ensuring that the integrity of the site is maintained and the site
makes an appropriate contribution to achieving favourable conservation status for each of
the qualifying features –– as described below, the habitats of the otter interest, including
the River Tay and resting-up sites, could potentially be affected by pollution and/or
sedimentation and this in turn would have an impact on otter
To ensure for the qualifying species that the following are maintained in the long term:
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population of the species as a viable component of the site – Loss of Atlantic
salmon connected to the SAC by contamination of watercourses may reduce the
occupation of the SAC and therefore the population of otters.
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distribution of the species within site – The loss of Atlantic salmon connected to the
SAC by contamination of watercourses may reduce the occupation of the SAC, and
hence the distribution within the SAC. This could in turn affect the Otter population
which feeds on them, and their distribution within the SAC. However, if the
mitigation as outlined in relation to contamination is applied, then it is possible to
conclude that distribution within the SAC will be maintained.
distribution and extent of habitats supporting the species - The proposal crosses the
SAC and pollution may affect the quality of the water and consequently the habitats
of the SAC.
structure, function and supporting processes of habitats supporting the species - As
above, any pollution incidents may affect habitats, the structure, function and
supporting processes of the SAC.
no significant disturbance of the species - The noise and vibration disturbance from
construction activities could result in significant disturbance to the qualifying
species within the SAC. If the displacement disturbance resulted in desertion of
this territory, this would constitute significant disturbance.
11 Consider whether mitigation measures can be The Environmental Statement proposes mitigation to address the impacts of the proposed
adopted to avoid impacts on site integrity
development. The proposed mitigation addresses the requirements as detailed in the
previous section for maintaining the habitats/qualifying species. Additionally, the
contractor would follow best construction site practices at all times and during all stages of
construction, including SEPA’s Best Management Practices, Pollution Prevention
Guidelines, and statutory conditions applied through General Binding Rules or higher CAR
authorisations. In addition, the following mitigation measures are proposed to address the
impacts of the proposed development:
(a) In respect of the River Tay SAC and the River Tay Catchment Area as defined by SNH:
• the outside edge of each tower base shall be a minimum of 50m from all watercourses and
water bodies within the SAC and a minimum of 50m from all watercourses and water
bodies within the River Tay Catchment Area unless the mitigation measures proposed in
Appendix 2 of Chapter 11 of Volume 2 of the Beauly-Denny PLI Report are implemented
to permit reductions in the distance specified;
• the outside edge of all borrow pits, quarries, etc. shall be a minimum of 50m from all
watercourses and water bodies within the SAC;
• the outside edge of all permanent non mobile storage facilities for oil, fuel etc. shall be a
minimum of 100m from all watercourses and water bodies within the River Tay Catchment
Area;
• no re-fuelling shall take place within 30m of watercourses and water bodies within the
River Tay Catchment Area;
• no generators and similar plant and machinery shall be used within 30m of watercourses
and water bodies within the SAC and within 10m of watercourses and 30m of water bodies
within the River Tay Catchment Area;
• no spoil heaps shall be constructed within 30m of watercourses and water bodies within
the River Tay Catchment Area unless mitigation measures similar to those proposed in
Appendix 2 of Chapter 11 of Volume 2 of the PLI report are implemented to permit
reductions in this distance specified;
• no operations involving concrete transfer between vehicles or into vehicles shall take
place within 30m of watercourses and water bodies within the River Tay Catchment Area.
The foregoing conditions apply to all works associated with the development.
(b) Resurveys for otter holts and resting sites in suitable habitats along the route and access
corridors within the SAC shall be carried out as part of the micro-siting process both prior
to the construction of the 400kV transmission line and the dismantling of the existing
132kV Beauly to Denny overhead transmission line. These surveys are required because of
the time periods between the original survey and potential construction of the 400kV line
and the dismantling of the 132kV line. It is possible that otters will have moved locations
and the surveys will form the basis for detailed mitigation plans for each tower location
and/or licence applications if necessary.
(c) No works in connection with the Development shall be commenced until an otter
management plan detailing all mitigation measures, including for situations of disturbance
and/or actual damage to places of shelter, has been submitted to and approved in writing by
the Scottish Ministers. The management plan as approved shall be implemented in its
entirety unless otherwise agreed in writing with the Scottish Ministers.
(d) The transmission line shall not be commissioned, i.e. transmit electricity between
Beauly and Denny until a plan for emergency repair/maintenance works within the SAC
has been submitted to and approved by the Scottish Ministers. Any emergency
repair/maintenance works shall be carried out in accordance with the approved plan.
Conclusion of Appraisal
12 Can it be ascertained that the proposal will Provided that the mitigation measures outlined in the relevant sections of the Beaulynot adversely affect the integrity of the Denny PLI Report and in section 11 of this assessment are adopted and implemented onthe-ground by means of enforceable conditions attached to any consent (through either the
River Tay SAC?
Electricity Act/Town and Country Planning Act or through CAR regulatory procedures)
then the Beauly Denny proposal will not adversely affect the integrity of the River Tay
SAC.