Scottish Government: Transport Directorate, November 2009
This document should be regarded as an Appropriate Assessment on the Implications of the proposed Aberdeen Western Peripheral
Route (AWPR) upon the River Dee Special Area of Conservation (SAC). It has been prepared by the Scottish Ministers as the
Competent Authority for the above proposal and is based on the framework provided in the European Commission’s guidance
document “Managing Natura 2000 Sites: The provisions of Article 6 of the Habitats Directive”, (European Commission guidance,
2000).
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Project and site description
Brief description of the project
The AWPR proposal comprises the construction of a new by-pass road for Aberdeen. It
comprises three sections – the northern leg, southern leg and a fastlink. It is 46km in length
and has been identified as a key element of an integrated transport system for the North
East of Scotland and is being promoted and funded primarily by Transport Scotland, an
agency of Scottish Government Ministers. Funding contributions are also being made by
the local authorities of Aberdeen City, and Aberdeenshire Councils.
The section of the AWPR which requires assessment under The Conservation (Natural
Habitats, &c.) Regulations 1994 (as amended), is that section of the route that is a proposed
bridge crossing over the River Dee Special Area of Conservation (SAC).
Further details on the actual design and build requirements for the AWPR of the River Dee
crossing are described in section 5 below.
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Brief description of the designated Natura The River Dee SAC is designated under the Directive 92/43/EEC.
site
The River Dee is a major east coast Scottish river, which flows uninterrupted for some
130km from its upland reaches in the high Cairngorms to the north sea. There is a weak
nutrient gradient along its length, but it is essentially a nutrient –poor river
The qualifying species are freshwater pearl mussel, Atlantic salmon and otter.
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Freshwater Pearl Mussel (Margartifera margaritifera)
The River Dee supports a functional population of freshwater pearl mussel, recorded from
a location approximately 30 km from the river source to approximately 6-7 km upstream
from its mouth. Juveniles make up approximately 30% of the recorded population, among
the highest proportions recorded in Scotland. This indicates that the population is recruiting
strongly and is one of the most important in the UK.
Atlantic Salmon (Salmo salar)
The River Dee supports a high-quality population in a river draining a large catchment on
the east coast of Scotland. There is a weak nutrient gradient along its length, but it is
essentially a nutrient-poor river. The high proportion of the river accessible to salmon has
resulted in it supporting the full range of life-history types found in Scotland, with subpopulations of spring, summer salmon and grilse all being present. The headwaters which
drain the southern Cairngorm and northern Grampian mountains are particularly important
for multi sea-winter spring salmon, but there has been a significant decline in their
abundance in recent years. The extensive areas accessible to salmon mean the River Dee
supports a significant proportion of the Scottish salmon resource. In recent years it has
contributed about 4 or 5% of all salmon caught in Scotland.
Otter (Lutra lutra)
Surveys have indicated that the otter is found throughout Dee catchment, from its mouth at
Aberdeen to many of the high-altitude lochs. The river system contains extensive areas of
suitable habitat for otter feeding, resting and breeding, including watercourses with a high
fish biomass and islands and marshy areas for resting. This is a strong, high quality
population, representative of north-east Scotland.
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Conservation objectives for the designated SNH provides details of all Natura site conservation objectives on its Website, SNHi can
Natura site
be found at http://www.snh.org.uk/snhi/
To avoid deterioration of the habitats of the qualifying species (listed below) 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
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conservation status for each of the qualifying features: and
To ensure for the qualifying species that the following are maintained in the long term:
● Population of the species, including range of genetic types for salmon, as a viable
component of the site
● Distribution of the species within the site
● Distribution and extent of habitats supporting the species
● Structure, function and supporting processes of habitats supporting the species
● No significant disturbance of the qualifying species
● Distribution and viability of freshwater pearl mussel host species
● Structure, function and supporting processes of habitats supporting freshwater pearl
mussel host species
The qualifying species are freshwater pearl mussel, Atlantic salmon and otter.
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5
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 Dee SAC.
designated Natura site?
Consider whether there are any likely direct, The southern leg of the AWPR requires a bridge over the River Dee. A viaduct bridge is
indirect or secondary significant effects of the to be constructed which will lie approximately 100m east of the existing Maryculter
project on the designated Natura site
Bridge. At the point of crossing the river is approximately 60m wide and the SAC is about
90m wide. The current design for the bridge comprises a main span of 120m with 2 further
side spans of 75m. There will be no bridge piers in the river channel or SAC. A minimum
buffer of 4m from the SAC boundary will be maintained during construction of the bridge.
On completion the minimum distance form the bridge pier to the SAC boundary will be
12.5m on the north side and 19.6m on the south side.
A drainage outfall from SUDS ponds will be routed to the River Dee. As the outfall would
be located within the SAC, small scale construction activity will be required within the
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SAC. This work will be carried out in low flow conditions.
Other activities in proximity to the River Dee include: clearance of vegetation and above
ground obstacles within the work corridors for the approach road to the crossing, stripping
of topsoil and construction of road embankments.
In addition to the River Dee crossing, the AWPR will cross or otherwise impact a number
of watercourses outwith the SAC, but within the River Dee catchment, north and south of
the main crossing. The Crynoch Burn and Culter Burn which are part of the River Dee
SAC, will be indirectly affected as they receive water from tributaries which are impacted
by the proposal.
Taken from Jacobs, April 2008, AWPR Report to Inform Appropriate Assessment (IIAA)
for the River Dee SAC. (Section 3)
On the basis of the information provided the AWPR, but in particular the construction of a
bridge crossing over the River Dee SAC, is likely to have significant effects due to
potential impacts on water quality, impacts relating to noise and vibration from piling and
also from illumination during the construction period. In addition there is the potential for
road traffic accidents involving otter during the operational phase of the bridge.
Atlantic salmon
Likely significant effects during construction phase - Yes
Potential impacts from changes to water quality, noise and vibration from piling and
illumination could affect the passage of fish, spawning and feeding habitats.
The
construction is due to last for 16 months with any night-time working to be agreed in
advance of works commencing.
Likely significant effects during operation phase – No
Once the bridge is built, it is not considered likely that there will be any significant effects
from its operation on the conservation objectives for salmon. The reasoning behind this is
based on evidence from other bridge construction projects where salmon have quickly
habituated to the presence of the structure and no change has been noted in distribution or
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numbers. There are currently a number of bridge structures which have recently been
constructed across other SACs designated for salmon. None of these structures have been
linked to any adverse impact on the Atlantic Salmon populations.
Fresh Water Pearl mussels
Likely significant effects during construction phase – yes
The effects outlined above on Atlantic salmon could potentially impact on the FWPM due
to the symbiotic relationship between the two species. There is also the potential for the
release of sediments directly impacting on FWPM through smothering and alterations to
river topography.
Likely significant effects during operation phase - No
It is not considered that during operation that there will be any significant effects on
freshwater pearl mussel directly or indirectly to their host species - salmon.
Otter
Likely significant effects during construction phase – yes
Vegetation clearance and earth moving are the most likely significant impacts likely to
occur and construction activities may fragment or sever foraging routes. An otter couch
will require to be destroyed in close vicinity to the bridge crossing. Holts will be protected
within 100m of the bridge.
Likely significant effects during operation phase - no
The operation of the bridge is unlikely to have a significant effect on otters as there is
evidence to suggest that they will habituate to traffic noise etc. No direct access onto the
bridge will be available with appropriate mammal fencing along the route, therefore road
traffic accidents (RTAs) are not likely to be a significant issue. A riparian vegetation strip
will be re-established and the maintenance of the 4m buffer strip during construction will
avoid severance of habitats along the River.
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Is the plan/project likely to have a significant Consideration was given by the Consultants as to any other projects within the River Dee
effect on any other SAC/SPA, either alone or that should be considered in combination with the AWPR. Advice was sought from a
in combination, with other plans or projects?
number of Regulating Bodies as to their knowledge of other projects planned. A detailed
list was provided and consideration against these projects is provided in the Report to
Inform the Appropriate Assessment. Refer to Section 9 and Appendix 10 of the Jacobs
IIAA Report.
Appraisal of Impacts on Site Integrity
Can it be ascertained that the proposal/plan
will not adversely affect the integrity of the
River Dee SAC?
Regulation 48 indicates that projects can be assessed which include mitigation to reduce or
avoid impacts to avoid adverse effect on integrity. The Consultants’ report to Inform the
Appropriate Assessment details a range of key mitigation measures that will be implemented.
The mitigation proposed ensures that the conservation objectives for each of the qualifying
species can be maintained in the longer term, therefore an adverse effect on the integrity of
the River Dee SAC can be avoided.
Advice provided by Scottish Natural Heritage (SNH) on 8th August 2008, in a letter to
Transport Scotland and also in a Written Submission to the Public Local Inquiry (PLI), dated
12th August 2008, indicates that they have concluded no adverse effect on integrity, subject to
inclusion of conditions / legal agreements to any consent.
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Conclusion of Appraisal
I am satisfied that the construction and operational phases of the AWPR can be undertaken
without any adverse impact upon the integrity of the River Dee SAC . This conclusion is
supported by Scottish Natural Heritage, in their capacity as Scottish Ministers statutory
nature conservation advisers.
Martin Milarky
An official of the Scottish Government
EDINBURGH
November 2009
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