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Sloy Hydro Power Station Project’s Environmental Impact

Project Description

With the current global concerns on climate change, Scotland is on a mission to facilitate the efficient use of renewable energy. One of the major forms of renewable sources of energy that Scotland has focused on is hydroelectric power (HEP). Sloy HEP station is a major conventional hydroelectric project and was commissioned in 1950. The power station produces approximately 130 million units a year with average rainfall, a capacity of 152.5 megawatts. This translates to a load factor of ten per cent (10%). Thus the power station is only used during periods of high demand. To increase the load factor of the Sloy power station, Scottish and Southern Energy (SSE) has proposed the extension of the existing Sloy HEP plant. The proposed scheme will increase flexibility on the national grid towards meeting the demand. The scheme will also help the UK to achieve its commitment to increasing the levels of electricity produced from renewable sources. This extension will reduce any constraint that could be likely on other schemes of renewable energy (Wharmby 2009, p. 23).

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The proposed scheme consists of the conversion of the existing Sloy HEP plant into a pumped storage scheme and the construction of a new pumping station. The proposed new station will allow water to be pumped to Loch Sloy from Loch Lomond when the demand is low, mostly at night or when there is an oversupply. The new station will be situated on the grounds of the existing scheme next to Inveruglas centre. Existing pipelines and tunnels will be used to pump the water to Loch Sloy from Loch Lomond. The new pumping station will have two vertical pumps with a water pumping capacity rate of 10m3/s, a deep shaft 17m below the level of Loch Lomond will be excavated on the northern side of the existing station for the installation of the pumps. Much of the new pumping station construction will be underground with a few surface buildings for operation and maintenance. The station will include two surface buildings for deliveries and electrical buildings, a forebay, a pumping hall and shaft situated under the surface building, a service yard and enclosure, two new buried pipelines, and a site establishment area (Wharmby 2009, p. 25).

The new station is expected to pump water from Loch Lomond to Loch Sloy at an approximate rate of 20m3/s for six hours. The water will then be discharged back to Loch Lomond. Within these six hours, it is estimated that 432000m3 water will be withdrawn from Loch Lomond, lowering its level by approximately 6mm and increasing the level of Loch Sloy by 0.4m. In case of heavy rainfall, which could lead to the overflow of Loch Sloy, the Pumping will be suspended. Owing to the fact that the proposed scheme is an extension of an existing scheme, the scheme with proper maintenance is expected to run indefinitely. In an event where the scheme ceases its operation, decommissioning will be undertaken and the site restored with the guideline from the relevant authority.

Project Location

The Sloy HEP scheme is located within Loch Lomond and Trossachs National Park. The proposed extension is next to the existing scheme, thus, within the same location. The Trossachs is one of the two national parks in Scotland, and about 24 km2 of the national park will be affected by the scheme. Loch Lomond is the biggest source of fresh water in Great Britain, with an approximate volume of 2628 million m3. The water is used for recreation, water supply and power generation purposes. Its water catchment includes; Endrick water, River Falloch, Fruin water, Luss water, and Douglas water. The direct catchment area for Loch Lomond is approximately 764km2 and has an average annual rainfall of approximately 2060mm from the catchments. On the other hand, Loch Sloy has a direct catchment of 205km2 with an average annual rainfall of over 3000mm. The northern junction of the existing Bell mouth junction, which has been used as secondary site access to the existing scheme, will be used as the main access to the new site (Wharmby 2009, p.25).

Project Location

Brief Scoping on Main Impacts

The proposed project will be sited within Loch Lomond, Trossachs National Park, and Loch Lomond National scenery. On the site, we have Inveruglas centre and Inversnaid hotel, which are popular sites for tourists. At Loch Lomond, water sporting activities such as sailing, canoeing and kayaking are common. Loch Sloy is also used for the conservation and preservation of Powan, a rare native aquatic species. On the NE of the power station, we have a site of special scientific interest (Ben Vorlich), and to the SW, we have ancient woodland, which is listed. The woodland consists of mature conifers, and red squirrels are found within this woodland. On the native woodland in the North, we have bird species totalling 39, and they include species such Sparrow hawk, swallow, Reed Bunting, Willow Warbler, and Oystercatcher. The species are classified as species of important conservation under European Law. The existing power station is a listed building, and there also exists an old military road and a castle which are considered of cultural importance. After scoping, the following areas were identified as areas that needed further investigation and assessment. They included; land use and recreation, animals and birds and their habitat, aquatic ecosystem, landscape, visual impacts and cultural heritage (Hanson 2000, p. 17, Weston 2000, p. 197 & Wharmby 2009, p. 36). Table I provides the interaction of project components and the elements of the environment, predicting the expected impacts on different elements of the environment.

Table I. Matrix table of the predicted impact.

Rock storage Pumping
Land use&
1 1 2 1
Mammals &
3 3 1 1
Bird Ecology 2 2 1 1
Aquatic ecology 3 1 3 2
Landscape 2 2 3 2
Cultural heritage 2 2 3 2
Visual Amenity 3 3 3 2
Noise 1 1 2 1

Interaction ratings (1- low, 2- moderate, 3- high)

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Aquatic Ecology (Fish)

Legislation & Policies Covering Fish

Though the Sloy HEP proposed plant was an extension of an existing scheme, it was required to carry out an EIA because the extension during the scoping stage was believed to have an impact on the environment. This was in accordance with the legal requirements and policies of the Scottish government. According to the European Union water framework directive (WFD) (Council Directive 97/11/EC), the water environment should be protected from human action impacts. To achieve this objective, Scotland enacted the water environment regulations 2005 (CAR) and appointed SEPA as the regulatory institution. SEPA regulates four activities that could have an impact on the water environment i.e. point source discharge, water impoundment and abstraction, and engineering work in or near water bodies.

Freshwater Fisheries Act (Scotland) 2003 (Davies et al. 2004, p. 43 The Scottish Government 2003, p. 9) that protect non-migratory fish was considered and schedule 5 of Wildlife and Countryside Act (WCA) 1981 section 9 that protect Powan. The proposed project considered the legal provision that prohibits releasing Ruffle into the wild section 14(1) of WCA. Catchment Management Plan (CMP) 2003 (Loch Lomond) (The Scottish Government 1999, p.16 & The Scottish Government 2003, p. 14), which covers water quality, conservation of water resources, and protection and enhancement of aquatic habitats and species was also considered during EIA. Apart from the above legal provision, the proposed scheme sought further guidance from Scottish Natural Heritage, which covers impacts of hydroelectric schemes on the environment, Natural Heritage 1999 on national planning policy guidelines, and Planning Advice Note (PAN) 60 of Planning for Natural Heritage (Scotland) 2000 (Council Directive 97/11/EC, SEPA 2006, p. 23 & Wharmby et al. 2000, p. 67).

Baseline Data

Physical Condition

Loch Lomond

Loch Lomond is divided into three basins, including the Northern basin, southern basin, and a transitional zone. The North basin is narrow and deep, while the south is wide and shallow. The basins shores of Loch Lomond consist of soft material (88%) and rocky shore (12%). The soft material includes glacial till, beaches, wetland, and vegetation. The Eastern side of the North Basin is steep and rocky but shows no sediment movement. The Western side is where the Sloy Power station discharges, and though it is steep, it has been modified by human activities. The south basin eastern side has individual sediment cells, which are rocky, and the western side shows no sediment (Hanson 2000, p. 8).

Loch Sloy

Loch Sloy shores are wide with a height of 2m. The shores are exposed and formed with cobbles, boulders and bedrock. There is no evidence of erosion nor sedimentation on the natural substrate (Hanson 2000, p.12).

Water Quality and Temperature

Loch Lomond

The northern basin, according to WFD, was classified as experiencing moderate pressure, and the chemistry was a standard and overall physicochemical quality high. The southern basin was under pressure through moderate. It is considered as water body at significant risk, chemistry standard high and overall physicochemistrically high (Adams et al. 2002, p.36).

Loch Sloy

Loch Sloy is classified as a water body at significant risk due to morphological changes, water flow regulation and abstraction. Overall, chemistry and physicochemical standards are high. Specific pollutants level standards are also good. Temperature data gives a belief of colder temperature in Loch Sloy than Loch Lomond (Adams et al. 2002, p. 37).

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Loch Lomond

Loch Lomond contains both native and exotic fish species and amounts to about twenty-two species. Fifteen of these are native, and seven are exotic. The most significant species due to their commercial value is Atlantic salmon, brown trout and sea trout. Powan is also a remarkable species found here (Adams 1994, p. 93). This species (Powan) lives in large clear water with deep water refuge. They spawn in Dec/Jan over a littoral environment. Data shows that the Powan population is declining in this region. River Lamprey is another species found in Loch Lomond and found nowhere else in Britain. Though many fish species have been found here for hundreds of years, new species were introduced but were never established. In the last 25 years, new species have been introduced, and they include gudgeon, dace, chub, and Ruffe, and these species are well established. The introduction of Ruffe in Loch Lomond has led to the decline of the Powan population. The Ruffe competes with other fish for food, and it feeds on Powan eggs (Adams et al. 2002, p.39 $ Adams 1994, p. 97).

Loch Sloy

The original fish species of Loch Sloy was brown trout and a few eels. Atlantic salmon are believed to have been introduced to Loch Sloy from Loch Lomond. This was as a result of the increased length, surface area, and depth caused by the Sloy HEP scheme. The scheme also eliminated the migration of eels into the reservoir. Powan was introduced to Loch Sloy as a way of conserving them from the invasive Ruffe in Loch Lomond. A survey conducted in 1991 showed that the Powan had established well in Loch Sloy and had increased in number. Recent data show that Powan is adapting well in Loch Sloy (Whitton 2000, p. 31 Maitland 1990, p. 256 & Davies 2004, p.43). However, Powan in Loch Sloy exhibits different features from those in other Loch. Powan from Loch Sloy have a shallow head, posterior eyes, and a large mouth compared with the other Powan.

The available baseline information for the Sloy scheme is inadequate in that the information is not in full detail. For example, the information on water quality (chemistry) is not detailed, and we are not able to determine the exact components present in the water. Also missing is the nutrition level in the water bodies, which is significant to determine fish population (Krokowski 2006, p. 11).

Prediction Method

In the determination of the impacts that the proposed Sloy HEP scheme will have on the fish species, especially those under legal protection, the project will use the matrix method of impact prediction. The matrix will show on one side the scheme activities that will be carried out from the start to the end of the project (Morris et al. 1995, p. 13). Bearing in mind that this scheme with proper maintenance will run indefinitely, the scheme activities will include site construction, scheme operation and maintenance. The other part of the matrix table will reflect the environmental components i.e. water and aquatic life (fish) that will interact with project activities. The interaction of each component of environment and scheme activities will intersect at a specific cell within the table, and criteria will be used to determine the significance of that interaction. Baseline information will be used to determine the significance of such interaction as it may be. The magnitude will be one of the criteria and will be assessed in terms of high, moderate, low or no change. It will also be assessed in terms of duration, extent, frequency, reversibility, and timing (Morris 1995, p. 17 & Maitland 2007, p. 22).

The other assessment criteria will be significance. This criterion will be measuring the positive or negative effect of scheme activities on an ecosystem. The EIA will focus on negative impacts only and will assess on the basis of site integrity and conservation status. The terms that shall be used to measure significance will be the significance of international, regional, national or local status. It will also be measured in terms of economic, social and cultural importance.

Mitigation Measures

One of the major negative impacts will be on the Powan species decline. The introduction of Ruffe from Loch Lomond will lead to a decline of Powan in Loch Sloy. Alternative safeguard sites will be established, and Powan will be introduced there as a conservation measure (Maitland et al. 1990, p.255). Regular monitoring of the Powan and Ruffe population will be carried out once the scheme start operation (Davies et al. 2004, p.73). To prevent fish entrainment into the pumps, the clear bar will be placed vertical dimension (SEPA 2006, p. 26). During construction, pollution prevention measures will be put in place. Noise from construction at inveruglas will be put under check through construction behind the tailrace cofferdam (Yelverton et al. 2009, p. 14 & SEL 2009).

Agencies Consulted

Several agencies will be consulted by the proponent of the proposed project, and these consultations will run from the screening stage up to during scheme operation and maintenance. The landscape institute will be consulted during the identification of the best site for the project. The agent will help in analyzing the character, quality and sensitivity to changes in the existing landscape. CFA Archaeology Ltd and Scottish Natural Heritage will also be consulted. This will be consulted during scoping stage to develop terms of reference in regard to cultural heritage and also in defining alternatives to the proposed scheme and mitigation measures for maximum conservation and preservation of cultural heritage. SEPA, which is the authority in charge of environmental issues, will be consulted throughout the project cycle. Other agencies that will be consulted during scoping include Loch Lomond &Trossachs National Park Authority and Historic Scotland. Besides the mentioned agencies, the project will also include wide consultation with the public. The public here includes the tourist, sports men and other persons that could be benefiting directly or indirectly from resources that will be affected by the scheme. Public participation will be at the assessment stage and formulation of project alternatives and mitigation measures.

Use of EIS

Once all the stages of the Environmental Impact Assessment processes are completed, a draft of the Environmental Impact Statement (EIS) will be prepared. This statement contains the impacts that the proposed action will have on the environment, both avoidable and unavoidable impacts and all alternative actions of the project. EIS will be presented to the relevant authority (SEPA). The authority will issue the document to the public so that they can have a second opportunity to comment. Once the public provides their comment, the draft will be returned to the proponent to incorporate the comments from the public. Then a final EIS and proposed action will be prepared. Once the final EIS is prepared, the public is not allowed to make any comment. But if they feel that some issues which they consider to be major were left out, they can protest the EIS to the Director of the agency. The director can ask for a revision of the EIS or ask the agency to offer an explanation to the protestor as to why their concerns were not considered. A supplementary EIS can be prepared to cover areas that were not considered. The final and the supplementary EIS will be presented to the relevant authority (project licensing authority) to study. It is through the information contained in the EIS on project impact on the environment that will guide the authority on whether to approve or decline approval for the implementation of the proposed action. Depending on the magnitude and significance of the environmental impacts, the project may be approved or one of its alternatives taken instead of the proposed action (Weston 2000, p, 202).

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List of References

Adams E. & Maitland, S., 2002. Introduction and Establishment of Fish Population in Scotland. Glasgow Nature, 23, 35-43.

Adams, E., 1994. Fish communities of Loch Lomond, Scotland. Hydrobiologia, 290, 91-102.

Council Directive 97/11/EC. Web.

Davies, C., Sheley, J., McLean, R., Gardiner, I., Harding, P. & Peirson, G., 2004. Freshwater Fish in Britain: Species &their Distribution. Harley Books, Colchester.

Hanson, J. & McGlashan, and J., 2000. Impact of Protecting Loch Lomond Bank: Research Report 154, SNH: Perth.

Krokowski, J. & Doughty, R., 2006. SEPA Technical Report on Changes in Trophic State & Phytoplankton Composition in Loch Lomond.

Maitland, P. & Lyle, A., 1990. Conservation of Great Britain Fish: Acting on 6 Declining Species. Journal of fish Biology, 37A, 255-256.

Maitland, P., 2007. Proposed Sloy Pumped Storage Scheme: Issue Impacting on Fish & Fisheries.

Morris, P. & Therivel, R., 1995. Methods of Environmental Impact Assessment. The Natural and Built Environment. UCL Press. Ordnance Survey. Web.

SEL, 2009. Subsea Noise Impact on Marine Mammals and Fish. Subacoustech Environmental Ltd Technical Report.

SEPA, 2006. Scottish Environmental Protection Agency technical Report.

The Scottish Government, 2003. The EIA-Water Management Scotland. Scottish Statutory Instrument 2003 No.341.

The Scottish Government, 1999. The Environmental Impact Assessment (Scotland) Regulations 1999. The Scottish Government Development Department.

Weston, J., 2000. EIA, Decision-making Theory &Screening &Scoping in UK. Journal of Environmental planning & Management, 43, 185-204.

Wharmby, C. & Oglethorpe, D., 2009. Environmental Impact Assessment. Enviros Consulting Ltd.

Whitton, A. & Potts, M., 2000. The Ecology of the Cynobacteria. Kluwer Academic Publishers.

Yelverton, T., Hicks, W. & Fletcher, R., 2009. Subsea Noise Impact on Marine Mammals & Fish. SEL Technical Report.

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