Combe Park Lodge Hydroelectric Scheme
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34 High Street The Exmoor Society Dulverton Conserving Exmoor for All Somerset TA22 9DJ Registered Charity No. 1160912 Tel: 01398 323335 62/11/18/013 13/12/2018 Brendon and Countisbury @ Combe Park Lodge, Lynton, Devon Proposed 250kW hydroelectric scheme, to include intake weir, buried pipeline, powerhouse building with ancillary equipment and grid connection. The Exmoor Society is a charity whose objective is to protect Exmoor National Park for the benefit of all. In principle, small-scale hydro-electric schemes are welcomed and supported as long as they are sensitive to the location, conserve the scenic quality including natural features, and do not adversely impact on the rich ecology and people’s enjoyment of the special qualities. The Exmoor Society has undertaken a site visit, walking from Combe Park House to Watersmeet and considered the various reports provided by the developers, other bodies and individuals in order to understand and carefully assess the impact of the proposed scheme. The Hoar Oak Water hydro-electric scheme is located in a river valley landscape that has many natural scenic features. It is a popular, well-used area, all the year round, and provides many people with a unique experience of a relatively untamed river with easy access. It is of the highest scenic quality and unique amongst Exmoor’s rivers and streams in providing such a naturalistic and picturesque landscape, much-loved and appreciated as being one of the most important examples of the National Park’s natural and cultural assets. The National Trust’s principles are to conserve places of natural beauty, protect landscapes and buildings of beauty or historic interest and to permanently preserve their natural aspect, features and animal and plant life. More recently it has included a commitment to provide alternative energy on its properties to help mitigate climate change. It states that this hydro- electric scheme will provide electricity equivalent to the consumption of 225 average homes per year saving 800 tonnes per year of CO2 emissions. Hydrology/Stream Abstraction 1. Water Flow. At times the hydro power project would take about 3/4 of the flow in the Hoar Oak, and would reduce the flow in Farley Water by up to about 38%. It is relevant that C F Brown for the National Trust states “Reduction of the flow is slight”. This is at odds with any normal view and casts doubt on the importance of flow in these reaches as it would significantly reduce the visual enjoyment and ecology of the area (see later comments). 2. Abstraction. The control of abstraction is a most important aspect. For instance, should the control system fail then at lower flows the whole of the Hoar Oak flows could be abstracted. The control appears to be based solely on the flow in the Hoar Oak catchment. There appears to be no control based on the Farley Water flows. It is unclear what control data will be used, where the control location would be, the Instrumentation system to be used, and how the system would actually be controlled. If planning permission is given, there needs to be a robust system such that when failure of the input data ceases, which is likely to occur occasionally on such a catchment, then abstraction should cease. 3. Bridleway Pipeline Route. The pipeline route along the bridleway from Hillsford Bridge to the East Lyn crossing is along a ledge generally about 3m wide but in places down 1 to 2.6m and in one place 2.3m. This will be tight on the width of the excavator and dumper. There are no passing places along about 900m of the route and rock outcrops in the uphill face and sometimes even in the base of the existing path. Much of the downstream face of the path is sub-vertical. The rock here is Hangman sandstone and is hard and angular, thus excavating this rock anywhere on the site is likely to require substantial effort by noisy jackhammers. There is no commitment that explosives will not be used or any reference to setting noise levels or the monitoring of such. The developers state “Bridleway. Apply robust silt-protection measures along proposed excavation route (in sections) to prevent silt run-off into the watercourse.” For much of the route the downhill slopes are sub-vertical with rock outcrops and vegetation. It would be easy for the digger to inadvertently drop excavated spoil over the downstream edge or for the downhill edge of the pipe trench, which is anyway loose fill, to collapse downhill. The risk of silt and rocks leaving the site is high and thus protection measures here are important to protect the vegetation and view of the downhill slope and the clarity of Farley Water. There are no silt/rock protection measures detailed throughout the construction period, what constitutes breach, and what action would be taken in the event of such a breach. Contrary to the sketches in fig. 9 of the Environmental Report, the Construction Management Plan gives the pipe cover as the standard 0.6m. With a pipe external diameter of 630mm, and about 70mm of pipe bedding material at the bottom of the trench, gives a trench depth of 1.3m. The pipeline would be made of plastic and there would need to be pipe bedding material around the pipe to ensure it is not punctured by the intact rock or the backfill. Thus much of the excavated material, and particularly the rock which is likely to be most of the excavated material, will not be suitable as backfill near the pipe. “Store excavated material in designated areas.” The bridleway ledge does not have widened areas suitable for spoil storage. The only appropriate area found is the working area near Hillsford Bridge and, because of the narrow track, that would require the spoil dumper and the vehicle or trailer carrying the 12m long pipes to back a long way along the narrow ledge. Whilst safety measures are the responsibility of the construction contractor, this is such a high risk, and no safety plan for this high risk situation has been set out. “Remove excessive material off-site.” Because of the space occupied by the pipe and the pipe bedding material, by our calculations at least 700m3 of excavated rock and spoil will need to be disposed of. This is a significant amount, comparable in volume to a new house. There are few such disposal sites within the ENP, especially in the Watersmeet area. The applicant has not identified in its submission the final disposal site for the spoil. Mr Robert King in his submission states: “At the public consultation exhibition I was informed by an engineer representing the National Trust that in places it might be found to be difficult to bury the pipeline beneath the bridleway because of the depth and size of the rocks, then the pipe could be laid supported on pads and covered with earth.” There is no such section shown in Fig 9 of the Environmental Report. The nearest is the cross section of the pipe laid in the uphill face. This would result in increased scar which would be visible from the A39 on the opposite side of Farley Water. The pipe would need granular bedding material around it to ensure no puncturing. There is hardly any earthfill available locally. In this area of high rainfall and steep gradients, the earthfill would be in danger of washing away and there is no detail that the soil-filled bags are secured, potentially leaving the pipe exposed and vulnerable to sunlight degradation. Considering the winding nature of the ledge and the 12m lengths of pipe, it would be difficult to follow the path unless the pipe was cut into short lengths. This risks leaving too small a ledge width for a safe bridleway. The 2 applicant has not suggested carrying out trial digging to ensure that burying the pipe is a practical solution. 4. Steps Pipeline. The section down the steps is steep, narrow, rocky, treed and twisting. Excavation here is almost certain to result in loss of trees and an appreciable scar in the hillside which is just opposite the main foot access to Watersmeet House. In our view the current method statement is inadequate in setting out or controlling the damage in this sensitive area. The developer has not prepared a detailed construction methodology showing the full extent of the scar and the impact. 5. Pipeline Programme. The project programme, Environmental Report section 14, shows the pipeline route taking four months to construct during September to December inclusive. The construction works are difficult to carry out and could lead to an overrun or work stoppage, should the cost of the scheme overrun its budget. We consider that, because of the nature of the work and the challenges involved, the risk of this occurring is high. 6. Noise during Operation. There will be noise from the turbine house and the generator. The planning application is vague in what the noise level will actually be at critical points for visitors. Ecology 1. If planning permission is given, it should be made conditional on obtaining all relevant permissions and licences from ENPA, NE and the EA, etc. All the relevant surveys, such as the dusk emergence and dawn re-entry surveys for bats as identified in Acer Ecology’s report, should be conducted so that that the application is viable in its entirety before planning permission is granted. Plans and documentation should be provided that include detailed descriptions of which trees and niche habitats and species are likely to be impacted so that more informed decisions can be made.