Scottish Government: Energy & Climate Change Directorate
Habitats Regulations Appraisal of the Implications of the proposed Forth Energy Grangemouth Biomass development
River Teith Special Area of Conservation
11 December 2012
The following appraisal has been prepared by the Scottish Ministers as the Competent Authority for the above proposal.
Description
1
Brief description of the project
The development is for a biomass fuelled electricity and heat generating station at the Port
of Grangemouth, Falkirk with an electricity generating capacity of up to 120MW. The
biomass will be delivered to the plant mainly by ship (directly to Grangemouth port), with
some additional fuel arriving by road or rail.
The principal components of the development comprise of:
 Power plant area
 Fuel storage area
 An electrical switchyard
 A covered conveyor system for transferring fuel
The design of the plant will include:
 A 110m tall stack
 A boiler hall
 A turbine hall
 Main fuel and mixed fuel stores both 20m tall
 Ash silos (12m tall)
 Two auxiliary boilers with a single 55m stack containing two flues.
 A cooling water extraction pipe from within the docks.
 A cooling water discharge pipe into the River Carron.
The main generating station will be located within the existing docks, about 300m away
from the nearest intertidal area. Cooling water will be extracted from within the docks,
and the resulting warm water will be discharged into the River Avon, approx. 300m away
from the main plant.
The River Teith SAC lies approximately 20km upriver of the proposed Port of
Grangemouth development.
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Brief description of the designated Natura The River Teith is designated as a Special Area of Conservation for the following qualifying
site
features:
 Atlantic Salmon (salmo salar)
 Sea Lamprey (petromyzon marinus)
 River Lamprey (lampetra fluviatilis)
 Brook Lamprey (lampetra planeri) – not found in the Firth of Forth (freshwater
only) and therefore requiring no further consideration.
Atlantic salmon, sea lamprey and river lamprey all migrate through the Firth of Forth
estuary as they travel between the sea and their spawning grounds in the River Teith SAC.
Adult fish migrate upriver towards the River Teith to spawn, whereas juvenile and subadult fish migrate downriver to the sea. The different life stages of each of the three
species migrate at diffent times of the year. As such, there are very few periods of of the
year when we could confidently predict that there are no migrating fish of any of these
species present in the Forth estuary. For the purposes of the HRA it should be assumed
that one or more of these species is likely to be migrating through the Firth of Forth year
round.
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Conservation objectives for River Teith SAC
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
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 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
Screening
4
Is the proposal directly connected with, or The proposal is not directly connected with, or necessary to, conservation management of
necessary to, conservation management of the River Teith SAC and therefore further consideration is needed.
the Natura site?
5
Is the operation likely to have a significant
effect on the qualifying interest? Consider
each qualifying interest in relation to
conservation objectives.
The operation of the Port of Grangemouth biomass development could potentially affect
the migration of fish species in the Firth of Forth through underwater noise and vibration,
chemical pollution or thermal pollution creating a barrier to fish movement within the
Forth estuary. These effects could only arise from operations associated with the
construction and operation of the discharge pipe within the River Carron (the
construction and operation of the main plant within the docks having no connectivity, in
this context, with the Forth Estuary and therefore in turn no connectivity with the
qualifying interests of the River Teith SAC).
The proposal could therefore cause significant disturbance to the following qualifying
interests: Atlantic salmon, sea lamprey and river lamprey and could therefore have a
likely significant effect on the SAC.
Appraisal
6
Identify the relevant conservation objectives
to consider for the River Teith SAC
The conservation objectives to consider for this site are:

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No significant disturbance of the species.
Can it be ascertained that the proposal/plan The ES and Information to Inform HRA has demonstrated that chemical pollution (e.g.
will not adversely affect the integrity of the spillages) will be avoided and thermal pollution will be confined within a short stretch of
River Teith SAC
the River Carron. Neither of these effects will therefore affect fish migration in the Forth
Estuary and therefore will not cause significant disturbance to the qualifying interests.
The ES and Information to Inform HRA did not adequately address the issue of noise and
vibration from piling operations which are potentially required for the construction of a
cooling water discharge outfall in the River Carron. However, the following objective
information can be used to assess this likely significant effect for any potential adverse
effect on site integrity:

The Firth of Forth is approximately 3km wide at this point.

The piling for the outfall would be within the River Carron, to the north of the
Biomass Plant site. The River Carron is separated from the adjacent Firth of Forth
intertidal mudflats by a breakwater (a stone faced earth bund). The outfall site is
located about 1.5km from the point at which the River Carron discharges into the
Forth estuary. The river channel between the outfall site and the river mouth
describes a shallow S-shaped curve.

The ES suggests that either non-percussive or percussive piling could potentially be
used (to be determined by ground conditions).

Proposed mitigation (from the ES):
o piling would limited to daylight hours, i.e. approx. 12-18 hours a day (if
undertaken in summer) - this could easily be limited by a conditon to 12
hours.
o Any percussive piling (if used) would be limited to a max of 6 hours a day
(this is a much noisier form of piling).
o The entire piling operation would take no more than 6 months.
Information that isn't provided is an estimate of noise levels produced by piling (nonpercussive or percussive). As a worst case scenario, if the noise was loud enough to carry
over the entire width of the estuary, fish migration could be disrupted for 12 hours a day
for 6 months.
95 dBht has been concluded in the ES of the Forth Replacement Crossing to be the noise
level (from a source such as piling) that would cause disruption to salmon (ES conclusion
based on a review of the scientific literature). Lampreys are far less sensitive to noise, so
for the purposes of this assessment salmon will be assessesed and it will be assumed that
if on adverse effect can be demonstrated for salmon this will also apply to lamprey
species.
Noise monitoring of non-percussive piling from the nearby Forth Replacement Crossing
has recorded source levels of 93 dBht falling to 63 dBht at 50m, 50dBht at 250m, 40 dBht
at 1,000m and 35 dBht at 2,500m. Background levels in that part of the estuary (from
shipping, bridge traffic noise, etc.) are around 30-40 dBht. These figures can be taken as a
reasonable representation of non-percussive piling.
Non-percussive piling is unlikely to produce noise that would significantly exceed 95dBht
at source, and any such noise is likely to attenuate fairly quickly – over 10s of meters to
much lower levels. Adding to this the further attenuation provided by the breakwater,
and 1.5km of curving river channel, we can be confident that non-percussive piling would
not produce noise levels in the Forth estuary that would be far below that which would
disturb salmon. We can therefore conclude that non-percussive piling would not have an
adverse effect on the integrity of the qualifying interests of the River Teith SAC.
Percussive piling produces much greater noise at source, and the nature of the noise
means that it tends to carry much further. Whilst the location of the outfall 1.5km
upstream from the mouth of the river would provide some attenuation, given the lack of
information about the type of percussive piling that might be used it cannot be ruled out
with sufficient certainty that noise from such operations could reach the Firth of Forth.
If percussive piling was to be used, mitigation (enforced through conditions) would be
required to ensure that noise levels of 95 dBht would not be exceeded in the Firth of
Forth estuary. Some mitigation is proposed in the ES, i.e. that there would be no night
time piling, that any percussive piling would be restricted to no more than 6 hours a day,
and that the entire operation would last no more than 6 months. This would restrict the
duration of any noise exceedance, but would not limit the noise levels themselves, with
similar results upon the levels of disturbance to the qualifying interests.
Therefore, the key mitigation is to limit the noise levels produced in order to remove any
adverse effects on site integrity. Any proposed piling operations could only be undertaken
if it can be demonstrated, through modelling prior to any such piling commencing, that
they would not produce noise exceeding 95 dBht at the mouth of the River Carron. This
can be achieved by various methods, e.g. creating a dry bunded area in which the piling
might take place, or other noise baffling techniques. The exact methodology need not be
specified at this stage.
If such mitigation is employed it is possible to conclude that piling operations in the
River Carron could be undertaken without causing significant disturbance to migratory
salmon and lamprey species from the River Teith SAC in the Firth of Forth.
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Consider whether mitigation measures or Mitigation, enforced through conditions, required to avoid impacts from percussive piling:
conditions to be adopted to avoid impacts on
site integrity
 Any percussive piling proposed must be demonstrated (prior to the start of cooling
water outfall construction operations) to produce no more than 95dBht at the
mouth of the River Carron. This must also be monitored during piling operations,
not as mitigation itself, but to ensure that the mitigation is operating correctly.
Additional mitigation should include;

Soft start methods must be employed

No night time piling (piling limited to no more than 12 hours a day)

Percussive piling limited to 6 hours a day

Piling operations to last no more than 6 months in total.
Conclusion
9
Can adverse impacts on site integrity be The Port of Grangemouth biomass application, will not adversely affect the integrity of
avoided ?
the River Teith SAC subject to implementation of the mitigation (enforced through
conditions) as detailed above.