Ballachulish Community Hydropower Scheme
River Laroch Feasibility Study
June 2014
Ballachulish & Glencoe Community Company
335086 001 A
PIMS/SNI/GLA/335086/REP/INT
4 June 2014
Ballachulish Community Hydropower Scheme
River Laroch Feasibility Study
Ballachulish Community Hydropower Scheme
River Laroch Feasibility Study
June 2014
Ballachulish & Glencoe Community Company
Mott MacDonald, 1 Atlantic Quay, Broomielaw, Glasgow G2 8JB, United Kingdom
T +44 (0)141 222 4500 F +44 (0)141 221 2048 W www.mottmac.com
Ballachulish Community Hydropower Scheme River Laroch Feasibility Study
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Revision Date Originator Checker Approver Description Standard
A 30/05/2014 A Davitti C Cload D MacDonald First Draft
Issue and revision record
This document is issued for the party which commissioned it and for specific purposes connected with the above-captioned project only. It should not be relied upon by any other party or used for any other purpose.
We accept no responsibility for the consequences of this document being relied upon by any other party, or being used for any other purpose, or containing any error or omission which is due to an error or omission in data supplied to us by other parties.
This document contains confidential information and proprietary intellectual property. It should not be shown to other parties without consent from us and from the party which commissioned it.
Ballachulish Community Hydropower Scheme River Laroch Feasibility Study
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Chapter Title Page
1 Introduction 1
1.1 Study Location _____________________________________________________________________ 1 1.2 Land Ownership ____________________________________________________________________ 2 1.3 Study Methodology __________________________________________________________________ 2
2 Potential Scheme Options 3
2.1 Discussion of scheme options _________________________________________________________ 3 2.2 Options identified ___________________________________________________________________ 4 2.2.1 Option 1 __________________________________________________________________________ 4 2.2.2 Option 2 __________________________________________________________________________ 6 2.2.3 Option 3 __________________________________________________________________________ 6
3 Engineering Assessment 8
3.1 Energy Potential Calculation __________________________________________________________ 8 3.2 Available Flow _____________________________________________________________________ 8 3.3 Critical Evaluation of LFE _____________________________________________________________ 9 3.4 Indicative Annual Revenue ____________________________________________________________ 9 3.5 Engineering Constraints _____________________________________________________________ 10 3.5.1 Access __________________________________________________________________________ 10 3.5.2 Scottish Water abstraction ___________________________________________________________ 11 3.5.3 Pipeline alignment _________________________________________________________________ 11 3.5.4 Grid connection ___________________________________________________________________ 12 3.6 Capital Costs _____________________________________________________________________ 13 3.7 Financial Analysis __________________________________________________________________ 14
4 Environmental Considerations 15
4.1 Approach to the Ecological Study ______________________________________________________ 15 4.2 Desk Study _______________________________________________________________________ 15 4.3 Desk Study Findings________________________________________________________________ 16 4.3.1 Statutory and Non-Statutory Designated Sites ____________________________________________ 16 4.3.2 Protected and Notable Species _______________________________________________________ 16 4.3.3 Invasive Species __________________________________________________________________ 17 4.4 Site Walk-Over Observations _________________________________________________________ 17 4.4.1 Terrestrial Ecology _________________________________________________________________ 17 4.4.2 Aquatic Ecology ___________________________________________________________________ 18 4.5 Potential Ecological Constraints _______________________________________________________ 18 4.5.1 Otters ___________________________________________________________________________ 18 4.5.2 Badgers _________________________________________________________________________ 18 4.5.3 Bats ____________________________________________________________________________ 18 4.5.4 Breeding Birds ____________________________________________________________________ 19 4.6 Recommendations for Further Survey Work _____________________________________________ 19
5 Conclusion and Recommendations 20
Contents
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5.1 Conclusions ______________________________________________________________________ 20 5.2 Recommendations for Further Work____________________________________________________ 20 Appendix A. Flow Estimate for the River Laroch ____________________________________________________ 22 A.1 Low Flows Enterprise FDC ___________________________________________________________ 22
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Ballachulish & Glencoe Community Company (B&GCC) expressed interest to
investigate the potential to develop hydro-power on the River Laroch, to the South
of the village of Ballachulish. The objectives are to provide a sustainable source
of electricity and revenue for the Community Company.
Mott MacDonald Ltd (MML) was commissioned to assess the
hydropower potential on the River Laroch watercourse, including initial
environmental, hydrological and economic analyses. The purpose of
this report is to further quantify the resource, scope options, identify
potential engineering and environmental constraints and provide outline
costs.
1.1 Study Location
The River Laroch catchment is located to the South of the village of
Ballachulish, approximately 17km south west of Fort William, draining
northwards into Loch Leven, which in turn connects to Loch Linnhe.
The River Laroch is approximately 7km long; it is a typical fast-flowing
Highland watercourse with a river bed mainly comprised of rocks and
boulders, and a step-pool morphology. The river network is essentially
a single channel, which drains the slopes of the surrounding peaks (i.e.
Sgorr Bhan, Sgorr Dhearg and Sgorr a’ Choise), and joined by several
minor tributaries.
The catchment is typical of upland catchments on the west coast of
Scotland, with a high Standard Average Annual Rainfall (SAAR) of
3007mm (Institute of Hydrology, 1999) and steep gradient. The
majority of the land cover of the catchment is mountain heath and bog,
with some areas of grassland and woodland (LCM 2000 dataset, CEH
website). There are no lochs present in the catchment to impact
runoff. The underlying geology of the catchment consists of low
permeability bedrock, which will result in a ‘flashy’ response to rainfall
events (BGS Hydrogeology Summary, CEH website). This means that
during rainfall events, runoff from the catchment will be fast, resulting in
a hydrograph which displays sharp peaks and short, steep recession
periods.
1 Introduction
Figure 1.1: River Laroch (upper
catchment)
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The land use in the catchment has a distinct contrast between the
upper and lower altitude areas. In the upper catchment (Figure 1.1) the
ground is blanket bog and wet heath which supports very low levels of
grazing.
In the lower catchment, to the east of the watercourse, the land use is
commercial forestry of mature age and planted very densely even along
the watercourses. This area, owned by the Forestry Commission of
Scotland (FCS), appears heavily modified, with the presence of a
disused Scottish Water Treatment Plant and intake structures, an
Archery Centre, slate quarries and a network of tracks and paths
popular amongst walkers.
1.2 Land Ownership
According to the OS maps available, the land located to the East side of
the lower catchment area belongs to FCS. The West side of the River
Laroch and the upper catchment are in private ownership. The River
Laroch and the existing fences are assumed to be ownership
boundaries, however they need to be confirmed.
As discussed with B&GCC, MML recommends that land ownership
should be investigated further. It is anticipated that any future
development is subject to agreement between the interested parties.
1.3 Study Methodology
A calculation of hydroelectric energy potential has been undertaken,
based on average rainfall and local topography from OS maps.
Indicative average annual revenue has been assessed, taking into
account the Government’s Feed-in Tariffs (FITs). High level capital
costs have been estimated, allowing a simple payback period to be
calculated in years.
The practicability of construction for each intake option, approximate
pipeline route, and powerhouse location has been assessed by desk
study and a site walkover carried out on 2nd
May 2014.
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2.1 Discussion of scheme options
The options considered are shown in Figure 2.1 below, with key
parameters given in Table 2-1. For all potential schemes, the
infrastructure would be located on the eastern bank of the River Laroch.
The grid references and elevations of the elements were obtained
during the site visit with a handheld GPS and will need to be confirmed
by topographic survey.
Figure 2.1: Map of Scheme Options Considered
Source: OS OpenData: contains Ordnance Survey data © Crown copyright and database right 2010
2 Potential Scheme Options
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Table 2-1: Key details of scheme options considered
Option Infrastructure National Grid Reference
Elevation Gross Head
Pipeline length
Max Power Output
Total Annual Energy Yield
Option 1 Intake NN 0810 5629 115m AOD 41m 950m 100 kW 399 MWh
Powerhouse NN 0820 5719 74m AOD
Option 2 Intake NN 0810 5629 115m AOD 66m 1350m 313 kW 964 MWh
Powerhouse NN 0815 5758 49m AOD
Option 3 Intake NN 0693 5478 243m AOD 128m 2100m - -
Powerhouse NN 0810 5629 115m AOD
2.2 Options identified
Three potential options were identified by MML personnel during the
site visit, as described below.
It should be noted that further survey and design work (as well as
costings) will be required to confirm the preferred options. The
information provided in this Feasibility Report should be considered as
preliminary to facilitate the discussion between B&GCC and MML in
order to determine the preferred option to develop further.
2.2.1 Option 1
The proposed intake for Option 1 would be located at NN 0810 5629,
approximately 350m upstream of the confluence between River Laroch
and its eastern tributary Allt Socaich, at an elevation of approximately
115m AOD. This section (Figure 2.2) is the highest point within the FCS
boundary suitable for an intake location, as the topography of the river
upstream of this section consists of steep banks difficult to access.
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Figure 2.2: Option 1 and 2 – Intake location.
The penstock would lie below ground on the east bank of the river, in
the strip of land between the access track and the watercourse. It is
anticipated that tree felling would be required to allow for the excavation
and laying of the pipeline.
Due to the presence of trees and difficult ground cover, the pipe route
was not surveyed in detail during the site visit, and it should be
considered preliminary until further studies are carried out.
The proposed powerhouse is located at NN 0820 5719, within the
ground adjacent to the watercourse and to the west of the disused
Scottish Water Treatment Plant.
Option 1 would benefit from having the infrastructure entirely on FCS
land and a relatively short pipeline, however the limited available Gross
Head (41m) would limit the available Power Output.
Flow and Head available make a Francis turbine appropriate for this
option, although alternative turbines might be suitable.
As an alternative powerhouse location, it may be possible to utilise the
existing Scottish Water Treatment Plant (Figure 2.3) to house the
Mechanical and Electrical equipment, however this would further
Figure 2.3: Ballachulish Water
Treatment Plant (disused).
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reduce the available head, as the Plant is located at a higher elevation
from the River Laroch.
2.2.2 Option 2
Option 2 has the same proposed intake location as Option 1.
However the proposed powerhouse would be located further
downstream on open ground (NN 0815 5758). This lower location
would require a longer pressure pipeline (and increased capital cost),
however this is compensated by a 50% increase of available Gross
Head and by the proximity to Grid Connection.
Similarly to Option 1, the penstock would be located on the east bank of
the river, in the strip between the access track and the watercourse. It is
anticipated that tree felling would be required to allow for the excavation
and laying of the pipeline.
Due to the presence of trees and difficult ground cover, the pipe route
was not surveyed in detail during the site visit, and it should be
considered preliminary until further studies are carried out.
Option 2 would benefit from having the infrastructure entirely on FCS
land.
Flow and Head available make a Turgo turbine appropriate for this
option, although alternative turbines might be suitable.
2.2.3 Option 3
Option 3 would have an intake located within the higher catchment of
the River Laroch, in order to maximise the elevation available. A
suitable intake location has been identified at NN 0693 5478 (Figure
2.5), upstream of a long river stretch with the watercourse lying in a
gorge.
The Powerhouse would be located at NN 0810 5629 (at approximately
the same location of the Intake for Options 1 and 2), with a buried
pipeline on the eastern bank and an available Gross Head of over
120m.
However, the benefits of the increased elevation would be outweighed
by a series of negative aspects, including:
Figure 2.4: Option 2 –
Powerhouse location.
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Reduction in catchment area and available flow;
The length of pipeline (approximately 2km) would make the
financial assessment of the development unviable;
Distance to Grid Connection;
The infrastructure would be located on a more environmentally
sensitive area;
The infrastructure would be almost entirely located within private
ownership;
It would be very difficult to access, construct and route a pipeline in
the sections below the intake, due to the steep topography of the
gorge.
Following the above considerations and in agreement with B&GCC,
Option 3 has been discarded and will not be considered further.
Figure 2.5: Option 3 – Intake location.
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3.1 Energy Potential Calculation
The energy potential of a hydropower scheme is a function of flow
(which depends on catchment area and rainfall) and the height through
which the water drops from the intake to the turbine or tailrace (known
as head).
As a first estimate for river flow, MML has used the data obtained
through Low Flows Enterprise (see Section 3.2). The head was
estimated using the elevations gathered during the site visit using a
handheld GPS. Both flow and head will be confirmed following
additional studies (i.e. topographic survey and, if required, flow
monitoring).
Standard values for efficiency and losses within the system have been
used to calculate annual energy generation. All schemes are assumed
to be ‘run-of-river’, that is no water storage.
3.2 Available Flow
SEPA has adopted the Low Flows Enterprise (LFE) software developed
by Wallingford Hydro Solutions as their initial point of reference for
evaluation of any abstraction licence application. This software utilises
data series from SEPA’s long term gauging stations selected for the
similarity of their hydrological characteristics.
The flow-duration curve (FDC) for the River Laroch used in this report
has been obtained through LFE software, and shown in Appendix A.
A more accurate FDC for the river could be developed through further
hydrological analysis. This may be required in due course by SEPA for
licensing under the Controlled Activities (Scotland) Regulations (CAR).
Improved confidence in the river flow patterns would improve certainty
in the predicted financial return of the scheme, and allow the turbine to
be sized more accurately to make best use of the available resource.
For small hydropower schemes, SEPA may also require a direct
measurement of low flow in the river to inform their determination of an
appropriate ‘hands off’ compensation flow that must be maintained in
the river.
This would require continuous flow monitoring equipment to be
installed for a period of 6 to 12 months. This would be calibrated by a
3 Engineering Assessment
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programme of spot flow measurements on the River Laroch, and linked
to an analogue catchment with a long gauged record. While flow
monitoring is not necessarily required for SEPA, it would further
improve confidence in river flows, which may be useful for potential
scheme funders.
3.3 Critical Evaluation of LFE
To improve confidence in the energy and financial calculations
undertaken using the LFE FDC estimate, a critical evaluation of the
data has been undertaken.
LFE is used to derive a FDC for the catchment in the absence of
gauged data. LFE uses a pooling group approach to derive the
catchment FDC estimate. This involves screening long term gauging
stations from the existing hydrometric network to identify which stations
have similar catchment characteristics to the catchment site, and using
data from each gauging station derives the FDC estimate. Comparing
the pooling group gauges to the target site allows an assessment of the
quality of the LFE FDC estimate and improves confidence that it is
providing a reasonable assessment of flows for the target catchment.
Table A.1 in Appendix A presents a comparison of pertinent catchment
characteristics between the River Laroch catchment and each of the
gauged catchments included in the pooling group. Each of the
characteristics is scored and colour coded as per the scoring matrix
presented in Table A.2 where green is a favourable comparison and red
is a poor comparison. The scoring is based on a SEPA scoring
mechanism which has been adopted as a standard for assessing LFE
FDC estimates.
A commentary on the compatibility of each of the characteristics of the
pooling group catchments is given in Appendix A.
The pooling group generally shows a good comparison with the
characteristics of the target catchment and therefore the LFE FDC is
thought to represent flows in the target catchment well. It is noted that
the low flow end of the LFE FDC may overestimate flows slightly.
3.4 Indicative Annual Revenue
The Feed-in Tariff (FIT) scheme is intended to encourage the uptake of
small-scale low carbon technologies up to 5MW, through tariff
payments made on both generation and export of renewable energy.
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The revenue can be broken down into two main components:
1. Generation Tariff
This is a fixed payment by the FIT Licencee (Registered Feed-in
Tariff Licenced Supplier) to the Generator for every kWh generated
by the installation. This rate varies based on the installed capacity
of any given scheme (Table 3-1), and is applicable for the 20-year
tariff lifetime. Note that these rates are subject to annual degression,
of which the future scale is unknown. Assuming that the hydro
scheme on the River Laroch will be pre-accredited by December
2015, in this report the revenue has been estimated assuming a
10% degression applying to the current tariff.
Table 3-1: Hydropower Feed-in Tariffs
Scheme Rating Present Generation
Tariff (p/kWh)
Future Generation Tariff (p/kWh) assuming 10%
degression
≤15 kW 21.12 19.01
15 - 100 kW 19.72 17.75
100 kW - 500 kW 15.59 14.03
500 kW – 2 MW 12.18 10.96
2 MW – 5 MW 3.32 2.99
Source: Ofgem, Feed-in Tariff Scheme: Tariff Table 1 April 2014 - 31 March
2015 Non-PV Only
2. Export Tariff
A payment to the Generator for every kWh exported to the
transmission or distribution network. The price for the export of
electricity is negotiated on the open market, however at present a
minimum of 4.77 p/kWh is guaranteed and this figure has been used
in this assessment, as this is not expected to decrease in future.
A combined rate of 22.52p/kWh (or £225.20/MWh) has therefore been
assumed for Option 1, and 18.8p/kWh (or £188/MWh) for Option 2.
3.5 Engineering Constraints
3.5.1 Access
The preferred intake site will require access for routine inspection and
screen clearing. This could comprise a defined access track or a quad
Figure 3.1: Forest Road.
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bike/Argocat route. Temporary access will also be required along the
pipeline route during construction.
For Options 1 and 2 the proposed powerhouse sites are located on the
eastern bank of the River Laroch within the FCS land. These locations
benefit from an existing Forest Road (Figure 3.1) which runs parallel to
the watercourse, minimising the need for additional access to the
powerhouse. Access agreements may be required with affected
landowners.
3.5.2 Scottish Water abstraction
Ballachulish Water Treatment Works (Scottish Water) historically
abstracted raw water from the Allt Socaich, with a maximum abstraction
of 110 m3/day. MML is aware that in 2006 Scottish Water requested an
increase in their abstraction from the Allt Socaich to 400m3/day,
following the loss of their additional intake on the River Laroch, and this
was acceptable to SEPA.
However, B&GCC have advised that the abstraction on the Allt Socaich
(Figure 3.2), and associated Water Treatment Plant, are currently
disused.
The evaluation contained in this report does not take into account a
possible additional intake for the hydro scheme on the Allt Socaich,
which could potentially increase the energy yield of the hydro
development.
It is recommended that Scottish Water, and Scottish Water’s
Redundant Assets Disposal Team, should be contacted with regard to
the use and sale of these assets.
3.5.3 Pipeline alignment
No detailed assessment of the pipeline alignment has been undertaken
to date. From the initial site walkover, no insurmountable pipeline
installation problems were identified, however dense ground cover
obscured large areas (Figure 3.3).
It has been noted that there are several side tributaries (Allt Socaich
and other minor drainage ditches) intersecting the potential pipeline
route. This would require further study with regard to suitable crossing
solutions (i.e. culverts or bridges).
Figure 3.2: Scottish Water
abstraction on the Allt Socaich
(disused).
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Further pipeline route investigation and a topographical survey are
strongly recommended.
Figure 3.3: Tree cover between Forest Road and River Laroch.
3.5.4 Grid connection
It has been assumed that the powerhouse can be connected to the
electrical grid at an existing pole in close proximity to the FCS fence
(Figure 3.4), which belongs to the local 11kV (three phase) line. This
will need to be confirmed with the Distribution Network Operator.
Given the close proximity to the potential grid connection point, it is
assumed that no high voltage transmission would be required for the
proposed powerhouse location. However, this will need to be verified by
Scottish & Southern Energy (SSE).
Figure 3.5 shows the location of the potential connection pole (also
shown in Figure 3.4) in relation to the sites selected for the
Powerhouse.
Figure 3.4 - Potential
Grid Connection pole.
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Figure 3.5 - Proposed connection to Ballachulish grid network.
3.6 Capital Costs
Indicative capital costs for the schemes have been assessed using
construction rates based on recent experience from other small
hydropower schemes in Scotland and observations made during our
site walkover.
An allowance of 25% has been included in the build-up of capital cost to
cover preliminaries and contingencies, based on our experience of the
construction of similar schemes.
Pipe Costs
Conservative pipe cost assumptions have been made based on
average rates obtained for recent similar schemes.
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M&E Costs
Costs for the turbine, generator, and other associated mechanical and
electrical plant are also based on recent similar schemes. Quotes
should be sought from suppliers once the preferred option is selected.
Table 3-2 shows indicative capital costs of Option 1 and Option 2.These
costs will be subject to change as the design develops and further
information becomes available.
Table 3-2: Indicative Capital costs of options considered
Item Option 1 Cost (£)
Option 2 Cost (£)
Development 35,000 45,000
Civil Cost 450,000 600,000
Mechanical and Electrical 250,000 350,000
Grid Connection 100,000 180,000
Design and Project Management
(10% of subtotal) 83,500 117,500
Preliminaries and Contingency
(25% of subtotal) 229,625 323,125
Total CAPEX 1,148,125 1,615,625
3.7 Financial Analysis
Predicted average annual revenue for each option has been calculated
as discussed in Section 3.4. Capital cost estimates (CAPEX) for each
option are as given in Table 3-2.
A simple payback period in years has also been calculated (Table 3-3),
based on capital cost divided by annual revenue. No consideration has
been given to running costs or discounting future expenditure at this
stage.
Table 3-3: Financial details of options considered
Scheme Number / Intake Location Option 1 Option 2
Max Power Output 100 kW 313 kW
Total Annual Energy Yield 399 MWh 964 MWh
Unit Rate 225.2 £/MWh 188 £/MWh
Annual Revenue £89,950 £181,364
CAPEX £1,148,125 £1,615,625
Indicative payback 12.76 years 8.91 years
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4.1 Approach to the Ecological Study
The ecological assessment comprises two components:
Desk-based study consisting of a review of available online literature and resources from relevant organisations and regulatory bodies.
Site Walkover which aimed to identify potential ecological features (including habitats and protected species) which could be impacted upon by the design of the hydro scheme.
4.2 Desk Study
A desk study was conducted to evaluate the nature conservation
importance of land within and surrounding the proposed hydro scheme
site. This comprised a search for statutory designated sites, protected
species records and local and national priority habitats and species.
Information was sought from a variety of sources including:
Scottish Natural Heritage (SNH)1 designated site database
Joint Nature Conservation Committee’s (JNCC)2;and,
The British Trust for Ornithology (BTO).
A search was conducted for the presence of any statutory designated
conservation sites within close proximity to the proposed hydro power
scheme including:
Internationally designated sites including Ramsar sites, Special
Protection Areas (SPAs), and Special Areas of Conservation
(SACs);
Nationally Designated Sites including Sites of Special Scientific
Interest (SSSIs) and National Nature Reserves (NNRs); and,
Local Nature Reserves (LNRs).
A 10 km radius was applied around the proposed scheme to assess where any development could possibly impact upon a designated area. Where appropriate this was extended to areas within the Zone of Impact (ZOI) for water catchments i.e. sites downstream.
1 http://www.snh.org.uk/
2 http://www.jncc.gov.uk/
4 Environmental Considerations
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4.3 Desk Study Findings
4.3.1 Statutory and Non-Statutory Designated Sites
Glen Etive and Glen Fyne Special Protection Area (SPA) qualifies
under Article 4.1 of EC Directive 2009/147 (The Birds Directive) by
regularly supporting a population of European importance of the Annex
1 listed species Golden eagle (Aquila chrysaetos), supporting 19 active
territories in 2003, more than 4.2% of the GB population.
The proposed scheme Options 1 and 2 are within 1km of the SPA
boundary, and therefore are close enough to require consideration for
this protected site.
The proximity of the SPA is however unlikely to form a constraint to the
hydro scheme. The proposed development will be discrete to its
location, any potential impacts will be localised and consequently will
have no impact upon the qualifying feature of this site. Consultation with
the relevant bodies will be undertaken to confirm that there are no
nesting golden eagle or other ‘Schedule 1;’ raptor species with the Zone
of Influence (ZoI) of the scheme.
4.3.2 Protected and Notable Species
An initial search of online data has identified records of protected,
relevant or important species occurring within the national grid squares
NN05, within which the proposed hydro scheme is located. These
include several protected mammal species:
European otter (Lutra lutra);
Eurasian badger (Meles meles);
Pine martin (Martes martes);
Eurasian red squirrel (Sciurus vulgaris);
Mountain hare (Lepus timidus).
It must be noted that SNH or SEPA may hold information regarding
populations of the mammal species noted above, not available to Mott
MacDonald without undertaking consultation. It is possible that such
statutory agencies would need assurance that these protected species
are not impacted upon, and require that detailed surveys to be carried
out.
Other protected or notable species identified during the desk study
included:
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Numerous breeding bird species including Schedule 1 listed
species and BoCC3 Red listed species;
Reptiles and amphibians including slowworm (Anguis fragilis) ) and
adder (Vipera berus );
Fish species including brown trout (Salmo trutta) and European eel
(Anguilla Anguilla).
4.3.3 Invasive Species
4.3.3.1 American Signal Crayfish (Pacifastacus leniusculus)
The highly invasive American Signal Crayfish was identified at a pond
in Ballachulish Quarry in July 20114. However, following a coordinated
effort from SEPA, SNH, The Highland Council and Lochaber Fisheries
Trust, the species was successfully eradicated. The River Laroch was
monitored, due to its close proximity to the infected pond (<400 metres)
and was confirmed to be free of this invasive species. This species is
therefore unlikely to form a constraint to the proposed scheme.
4.4 Site Walk-Over Observations
4.4.1 Terrestrial Ecology
The land use in the catchment has a distinct contrast between the
upper and lower altitude areas. Habitats surrounding the upper
catchments comprise of a mosaic of wet/dry heath and blanket bog, but
is dominated by large open expanses of dry heath, dominated by ling
(Calluna vulgaris), with scattered areas of silver birch trees (Betula
pendula).
Habitats in lower areas comprise of commercial forestry, with a more
semi-natural fringe containing silver and downy birch, rowan (Sorbus
aucuparia), and hazel (Corylus avellana),along the eastern banks of the
River Laroch.
3
4 Biocide Treatment of the Ballachulish Quarry Ponds to Eeradicate American Signal
Crayfish. Final Project Report. Lochaber Fisheries Trust . (2012)
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4.4.2 Aquatic Ecology
A detailed assessment of the aquatic ecology of the River Laroch has
yet to be conducted. During the walk-over, no areas of suitable
spawning grade substrates were observed which would be required to
support breeding migratory fish species such as Atlantic salmon (Salmo
salar) or sea trout (Salmo trutta trutta). A number of potentially
impassable obstacles were observed, which further support the
assessment that the river is unlikely to be an important salmonid river.
4.5 Potential Ecological Constraints
4.5.1 Otters
Terrestrial and riparian habitats of the River Laroch and tributaries are
suitable for otters, although no indicative field signs of otter were
observed during the ecological walkover of the site. Evidence is
available to suggest the presence of otters in the wider area, including
protected otter holts. An otter survey is therefore proposed as part of
the ecological survey strategy, to inform relevant mitigation
requirements.
4.5.2 Badgers
Although no indicative field signs of badgers were observed during the
ecological walkover, surrounding habitats are considered suitable and
evidence is available to suggest their presence in the wider area. A
badger survey along the route of the pipeline is proposed as part of the
ecological survey strategy to inform relevant mitigation measures.
4.5.3 Bats
A number of bat species, including Pipistrelle (Pipistrellus spp.) are
confirmed as being as being present within <10km, however further
scoping of the site will be required to fully establish the importance of
the area to local bat populations. The absence of mature woodland and
specific suitable habitat features within the zone of potential impact
would mean bats are unlikely to form a potential constraint to the
scheme.
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4.5.4 Breeding Birds
BTO records confirm the presence of Schedule 1 species such as
Golden eagle, Hen harrier (Circus cyaneus) and Merlin (Falco
columbarius) in the wider area. Given the presence of typical upland
habitats, there is potential for ground nesting bird species to nest at the
time when works are being conducted. These could form constraints
during the construction phase such as delays during the period in which
birds are nesting.
4.6 Recommendations for Further Survey Work
On instruction to progress with development of the scheme, Mott
MacDonald’s initial action will be to undertake consultation as part of a
screening stage. This would provide the relevant agencies such as
SEPA and SNH with an opportunity to highlight any potential concerns
they have. As mentioned these organisations, who have regional offices
and local knowledge of the site and wider area, may possess
information (through records and anecdotal evidence) regarding the
presence of protected and notable species, as well as the distribution of
sensitive habitats. Concerns that they may have, other than those
listed within this report, would be highlighted by such an exercise
The following ecological surveys are expected to be a requirement to
form a baseline for the Laroch hydro power scheme environmental
assessment.
Phase 1 habitat survey with habitat mapping,
Protected Mammal Survey (including otter, badger, pine martin, red
squirrel);
Aquatic ecology surveys.
Surveys which may be requested by statutory consultees may include
the following:
River Habitat/Fish habitat surveys;
Bird surveys;
Detailed NVC vegetation surveys;
Invertebrate surveys (aquatic and terrestrial);
Rare Bryophyte survey.
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5.1 Conclusions
From currently available information, our initial walkover and desktop
assessment of potential, two options of a small hydropower scheme on
the River Laroch appear technically and economically feasible.
Option 1 (100kW) is estimated to produce an Annual Average Energy
Production of approximately 400 MWh. Assuming a 10% degression in
the current Feed-in-Tariffs (for the sub 100kW tariff banding), the
scheme has the potential to generate an annual income of around
£90,000.
Option 2 (313kW) would benefit from a lower Powerhouse location: its
estimated Annual Average Energy Production is approximately 965
MWh. Assuming a 10% degression in the current Feed-in-Tariffs (for
the sub 500kW tariff banding), the scheme has the potential to generate
an annual income of around £180,000.
There is potential to increase output and revenue by utilising flow from
Allt Socaich, a side tributary of the River Laroch.
The initial environmental desk study has not identified any significant
environmental constraints to the project, however further consultation
with stakeholders, and environmental survey work will be required as
the project progresses.
There is the potential for protected species (including otters, badgers,
pine martens and bats) to be present in the development area. It could
be a constraint to the development if they are found to be present,
requiring appropriate mitigation.
It should be noted that scheme development is dependent upon
resolving all necessary licences and permissions, and the scheme
viability should be rechecked at key stages through the development
process, or as key events occur.
5.2 Recommendations for Further Work
To progress the project we recommend discussion within B&GCC in
order to choose the preferred option to develop further, and to proceed
with the activities included in the Stage 2 of our Proposal.
This includes:
Investigation of grid capacity availability with the Network Operator,
through an application for Grid Connection.
Liaison with SEPA and submit a CAR screening document.
5 Conclusion and Recommendations
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Review of environmental, ecological and archaeological constraints
and carry out initial consultation (Screening Report) with the local
Planning Authority (the Highland Council) to establish the likely
response to planning consultation.
Consultation with landowners that might be affected by the proposed
development.
As the summer months are usually the optimum time to undertake
the ecological surveys, mobilisation of these is also advisable.
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A.1 Low Flows Enterprise FDC
Figure A.1: LFE catchment FDC Estimate
Source: Wallingford Hydrosolutions Ltd.
Percentile Flow (m³/s)
Q5 1.725
Q10 1.187
Q20 0.715
Q30 0.459
Q40 0.302
Q50 0.202
Q60 0.136
Q70 0.093
Q80 0.062
Q90 0.037
Q95 0.027
Q98 0.018
Q99 0.014
Appendix A. Flow Estimate for the River Laroch
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Table A.1: LFE Critical Evaluation
Station Name River
Station No. Easting Northing
Catchment Area (km²) Proximity
SAAR (mm)
BFIHOST(SCOT) BFIHOST
Q95/Qmean (%) Land Cover
Underlying Geology
Target River
Laroch N/A 208104 756291 5.61 N/A 3007 0.258 0.359
5.86
Woodland: 5 %
Arable / horticultural: 0.0 %
Grassland: 20 %
Mountain / Heath / Bog: 75 %
Urban Extent: 0.0 %
Low perm. Bedrock: 100.0 %
Succoth Eas a Ghaill
89009 220649 726481 10.2 32.34 3094 0.285 0.384 4.60
Woodland: 39.1 %
Arable / horticultural: 0.0 %
Grassland: 34.7 %
Mountain / Heath / Bog: 31.8 %
Urban Extent: 0.0 %
Low perm. Bedrock: 100.0 %
Inverlochy Lochy 89005 219692 727471 47.1 31.06 2946 0.258 0.366 7.10
Woodland: 34.9 %
Arable / horticultural: 0.0 %
Grassland: 26.1 %
Mountain / Heath / Bog: 36.2 %
Urban Extent: 0.0 %
Low perm. Bedrock: 100.0 %
Glen Strae Strae 89004 215033 729930 36.6 27.26 2772 0.256 0.362 5.19
Woodland: 6.5 %
Arable / horticultural: 1.0 %
Grassland: 61.0 %
Mountain / Heath / Bog: 30.0 %
Urban Extent: 0.0 %
Low perm. Bedrock
100%
Victoria Bridge
Linne nam
Beathach 89002 227189 742153 49.9 23.75 2905 0.295 0.384 5.16
Woodland: 7.3 %
Arable / horticultural: 0.2 %
Grassland: 49.4 %
Mountain / Heath / Bog: 39.8 %
Urban Extent: 0.0 %
Low perm. Bedrock: 100.0 %
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Station Name River
Station No. Easting Northing
Catchment Area (km²) Proximity
SAAR (mm)
BFIHOST(SCOT) BFIHOST
Q95/Qmean (%) Land Cover
Underlying Geology
Glen Orchy
Orchy 89003 224259 731917 252.8 29.24 2724 0.264 0.359 7.07
Woodland: 11.0 %
Arable / horticultural: 0.4 %
Grassland: 39.7 %
Mountain / Heath / Bog: 45.8 %
Urban Extent: 0.0 %
Low perm. Bedrock: 100.0 %
Table A.2: LFE Critical Evaluation Scoring Criteria
Feature Scoring Criteria
Catchment Area Catchment Area score (a multiplicative factor of the target, generally*):
Area : < 5= green, 5-10 = yellow, 10-100 = orange, > 100 = red
(This is a multiplicative factor of the target)
e.g. target area is 5 and analogue is 30 then score is 6, yellow.
* In the unusual event that the analogue area is smaller than the target area then the score would be less than one and hence green. In this case take the factor of the analogue area and score that instead.
Proximity Distance/proximity score (arithmetic difference from target in km):
Distance: < 25km = green, 25 - 50km = yellow, 50 - 150km = orange, > 150km = red
SAAR SAAR 6190 score (difference from target):
SAAR : <200 = green, 200-400 = yellow, 400-800 = orange, >800 = red
BFIHOST SCOT BFI HOST (SCOT) score (arithmetic difference from target): *AUTOMATIC SCORING*
BFI HOST (SCOT): < 0.05 = green, 0.05 – 0.1 = yellow, 0.1 – 0.15 = orange, > 0.15 = red
BFIHOST AS BFIHOST(SCOT)
Q95/QMean Q95 / Qmean score (% difference from target):
Q95 / Qmean score: < 0.75%= green, 0.75 - 2% = yellow, 2 - 5% = orange, > 5% = red
Land Cover Assessed on a case by case basis due to multiple variables
Underlying Geology Assessed on a case by case basis due to multiple variables
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Review of Pooling Group Comparison
Catchment Area
The target catchment has a small catchment area, which is not
regularly replicated in the existing hydrometric network and hence all
the gauges in the pooling group have a larger catchment area than the
target catchment. Despite this the comparison is considered
reasonable.
Proximity
The hydrometric network is relatively dense in the area surrounding
Ballachulish and therefore all five of the pooled gauges are located
within 35km of the target catchment. All catchments will be subject to
similar climatic conditions as the target catchment which is important
given the west to east rainfall gradient for Scotland.
SAAR
The pooling group Standard Average Annual Rainfall (SAAR) values
show a favourable comparison to the target catchment, with three good
scores and two moderate/good scores. This is important as the target
catchment lies in a high rainfall area, with all pooled gauges also
receiving high rainfall.
BFIHOSTSCOT / BFIHOST
The pooled base flows show a good comparison score, and will
replicate the base flows of the target catchment well.
Q95/Qmean Ratio
The Q95/Qmean ratio comparison is favourable, though the gauges at
Inverlochy (7.10%) and Glen Orchy (7.07%) both show a slightly higher
ratio than may be expected given the location and characteristics of the
target catchment. The LFE FDC returns a ratio of 5.86% which is
reasonable, but shows the LFE FDC estimate may be overestimating
low flows slightly.
Land Cover
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The pooling group gauging stations have larger catchment areas than
the target site and therefore show an increased diversity in their land
cover types. The comparison is still regarded to be moderately good,
with all the pooling group catchments showing a reasonable percentage
of mountain, heath, bog and grassland cover. It is noted that the
gauged catchments at Succoth and Inverlochy have over 30%
woodland coverage which will have an impact on catchment runoff and
the gauged FDC at these locations. Despite the woodland coverage
there is no clear impact on the LFE FDC estimate that can be attributed
to it.
Underlying Geology
All pooling group catchments show low permeability bedrock covering
their entirety as per the target catchment. Permeability controls how
the catchment reacts to rainfall, and therefore as all catchments show
the same permeability as the target catchment, the LFE FDC will
replicate response to rainfall well. This is linked to base flow and
explains the close comparison in the base flow category.
Conclusions
The pooling group generally shows a good comparison with the
characteristics of the target catchment and therefore the LFE FDC is
thought to represent flows in the target catchment well. It is noted that
due to the higher Q95/Qmean ratios at Inverlochy and Glen Orchy the
low flow end of the LFE FDC may overestimate flows slightly.