Resource Documents: Northern Ireland (3 items)
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Author: Northern Ireland Environment Agency
What impact can a wind farm have on groundwater?
The development of a wind farm has the potential to impact on groundwater quality, groundwater quantity and/or the established groundwater flow regime. Figure 1 shows the scale and extent of the foundation of a single wind turbine which could potentially impact on the aquatic environment. Changes to the local water environment can affect receptors such as wells/boreholes, springs, wetlands and waterways, and can also have implications for groundwater dependent ecology and/or land stability.
The key impacts to groundwater that can result from the construction, operational and decommissioning stages of wind farms are summarised in Table 1 below.
Table 1: Potential impacts on groundwater from wind farms
|Construction Phase||Operational Phase||Decommissioning Phase|
|Groundwater Flow Regime||Earthworks and site drainage:
• Reduction in water table if dewatering is required for turbine foundation construction or borrow pits;
• Changes to groundwater distribution and flow.
|Physical presence of turbines and tracks:
• Possible changes to groundwater distribution;
• Reduction in groundwater storage.
Reduction of forestry in site area:
• Changes to infiltration and surface runoff patterns, thereby influencing groundwater flow and distribution.
|Physical presence of former turbines and tracks:
• Possible changes to groundwater distribution;
• Reduction in groundwater storage.
• Disturbance of contaminated soil and subsequent groundwater pollution.
• Pollution from spills or leaks of fuel, oil and building materials.
• Pollution from spills or leaks of fuel or oil.
|Use of vehicles and machinery to remove infrastructure:
• Pollution from spills or leaks of fuel or oil.
Download original document: “Wind farms and groundwater impacts”
Author: Northern Ireland Assembly Committee for the Environment
This report sets out the key conclusions and recommendations of the Committee for the Environment on its inquiry into wind energy, and the evidence considered by the Committee which led to those conclusions.
The terms of reference for the inquiry were:
- To assess the adequacy of PPS18 and related supplementary guidance in regulating proposals for wind turbines on a consistent and strategic basis, with due regard for emerging technologies and independent environmental impact assessment;
- To compare the perceived impact of wind turbine noise and separation distances with other jurisdictions and other forms of renewable energy development; and
- To review the extent of engagement by wind energy providers with local communities and to ascertain how this engagement may best be promoted. …
Key conclusions and recommendations
The Committee came to the following conclusions and recommendations after due consideration of the evidence before it.
The first term of reference relates primarily to the adequacy, or otherwise, of Planning Policy Statement 18 (PPS 18). The current policy is set out in PPS 18, with a slightly different approach proposed in the draft Single Strategic Planning Policy (i) to remove the significant weighting of wider environmental, economic and social benefits considerations, and (ii) to urge a cautious approach to the siting of turbines in Areas of Outstanding Natural Beauty (AONBs) or other designated landscapes. …
The Committee found that many submissions to the inquiry focused on perceived inadequacies of current planning procedures. Members expressed concerns that there may not be adequate consideration of the cumulative impact of turbines, but they recognised that balancing individual applications against cumulative effect is a wider issue across planning. The Committee recommends that procedures should be put in place so that a saturation point is clearly defined, rather than being a judgement call of individual planning officials.
The Committee considered the present situation in Northern Ireland where local councils have to devote finite resources to the investigation of noise complaints made against wind turbines. This contrasts with other areas of the UK where the developer is required to undertake investigation of any complaints and to demonstrate compliance with noise limits. The Committee therefore recommends that the standard conditions which were developed by the Institute of Acoustics, and which have been endorsed in Scotland, England and Wales, should be routinely attached to planning consents in Northern Ireland. …
Wind turbine noise and separation distance
The second term of reference of the inquiry focuses on wind turbine noise and separation distances from dwellings. This has been the most emotive aspect of the inquiry as many submissions detail the adverse impact perceived noise from wind turbines is having on the respondents’ day to day lives. From the evidence put before the Committee, it seems apparent that current guidelines in respect of permissible levels of noise are no longer adequate and that the research evidence available has increased significantly since 1997. The Committee therefore recommends that the Department should review the use of the ETSU-97 guidelines on an urgent basis, with a view to adopting more modern and robust guidance for measurement of wind turbine noise, with particular reference to current guidelines from the World Health Organisation.
The Committee was also concerned that there does not appear to be continuous long-term monitoring of noise from wind farms, either by developers or by the relevant public sector organisations. If such information were available it would introduce an objective measure of the noise output of turbines, as opposed to the projected noise impact produced by a desk-top exercise as part of the application process. This would provide both developers and planners with factual evidence and a useful assessment measure for future applications. The Committee recommends that the Department should bear responsibility for ensuring that arrangements be put in place for on-going long-term monitoring of wind turbine noise.
Following on from this, the Committee has heard evidence from local residents who are concerned about potentially harmful low-frequency noise emitting from wind turbines. The Committee is not in a position to determine the scientific basis for such information, but members believe that it warrants further investigation. The Committee therefore recommends that the Department, working with local universities, should commission independent research to measure and determine the impact of low-frequency noise on those residents living in close proximity to individual turbines and wind farms in Northern Ireland.
The Committee is aware that PPS 18 advises that a separation (or setback) distance of 500m, or 10 times rotor diameter, will generally apply to the siting of wind developments, but there is no indication given in the policy whether this is in relation to noise or to visual amenity. The Committee’s specialist advisor has indicted that, due to local topography, linear distance is less important than the robust actual measurement of noise, but it is obviously very relevant to the aspect of visual amenity. There are no generally agreed separation distances in other jurisdictions and the lack of prescription has given rise to a great deal of criticism from respondents.
The Committee has considered whether the current degree of flexibility should continue to be available to planners in assessing applications, but agreed instead that a minimum setback distance should now be determined by the Department. The Committee recommends that the Department, taking into account constraints on the availability and suitability of land for the generation of wind energy, should specify a minimum separation distance between wind turbines and dwellings. …
The final term of reference for the inquiry relates to the extent of engagement by wind energy providers with local communities and the promotion of such engagement. The Committee found that, although the wind industry is aware of the vital importance of engagement and is moving towards a more robust standardised approach (as exemplified by the recent publication of the NIRIG Community Best Practice Guidance 2014), many residents still feel marginalised in the whole process of siting wind developments near their homes.
The Committee believes that the views of the community must be given consideration by both planners and developers. Community concerns regarding visual amenity, noise and health, and the impact on house prices, are often not given due regard; and community groups trying to investigate or object to applications find the process resource-intensive and not transparent. This should not be seen as a mere box-ticking exercise – the views of residents need to be listened to, considered and, if possible, changes made to take account of these views. It is not just about preparing reports: there is a need to act on the findings.
The Committee believes that there should be timely and early engagement with communities. It recommends that the use of a community engagement toolkit should be made mandatory, as a useful measure of independence, and the list of statutory consultees should be widened to reflect all users of the countryside. …
The possible devaluation of homes, where wind developments have been sited in close proximity to existing dwellings, has been a contentious issue. While the Committee has been presented with emerging and contradictory research evidence on this, it believes that a scattered rural population – both those who have lived in the area for generations and those who have chosen to live in quiet scenic locations – has some cause for grievance. The Committee therefore recommends that the developer gives consideration to providing compensation where there is clear and compelling evidence of a significant drop in house value directly relating to the siting of a wind development. …
Download “Report on the Committee of the Environment’s Inquiry into Wind Energy”:
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Author: Walsh, Ursula
The Chairperson: I welcome Mrs Ursula Walsh from the University of Ulster, who has been appointed as our special adviser on acoustics, and invite her to make a five- or 10-minute presentation to the Committee, after which members will have an opportunity to ask questions. Thank you very much for your hard work; you have done a very big piece of work.
Mrs Ursula Walsh (University of Ulster): Good afternoon. I want to give you a brief overview of my paper and, perhaps, explain a couple of terms, after which we can have a discussion.
Noise is quite complex. Sound becomes noise when it becomes unwanted. People’s perceptions of noise are related not just to the volume of the noise but to its pitch or frequency and character. Two noises might be at the same volume, but one might be much more annoying than the other because of its character and fluctuations, which I will talk about. It also depends on the time of day. Obviously, if people’s sleep is disturbed, it is much more annoying than it perhaps would be during the day.
There is a human reaction to the annoyance caused by wind turbine noise. Sometimes, people are more annoyed because they feel a lack of control or they have feelings of injustice that they are not being heard or believed. Therefore, there is a subjective element to it. However, some people’s being more sensitive to noise than others has not been found so much with wind turbine noise.
Some of the general terms that you come across in all the noise guidance are not everyday terms, so the inquiry asked me to explain some of them. Leq is, more or less, the average sound. If you get all the sounds together, it is an average. L90, which is referred to extensively in the wind turbine guidance ETSU, is more or less the background noise remaining when you remove the noisiest elements. It would not be your average noise; it would be the remaining noise. It would be low-level noise, about two decibels lower than Leq.
When you see those terms and there is a small subscript “A”, as in LAeq, that “A” means that it has been adjusted, weighted. The “A” gives more weighting to high-frequency noise and removes decibels in low-frequency noise. In other words, it will give you a reading that makes higher-frequency noise more important. It diminishes low-frequency noise. That “A” weighting means that some pitches are enhanced and lower ones are diminished, if that is clear.
Noise comprises pressure waves and they spread out in the environment. They are affected by weather, so on still nights noise will travel better than on windy days. It also depends on the landscape. With distance, high frequencies and high pitches are absorbed in the atmosphere much more than low frequencies and low pitches.
If an airplane is going past you, for example, you will hear the low-frequency element; you will hear the drone. You will hear not high-pitched noises but low-pitches noises even though the noise, if you were beside the airplane, would have high and low frequencies. At a distance, you tend to hear the lower frequencies.
Wind turbine noise is mainly dominated by aerodynamic noise – the swish of the blades going round in the air – and most of the noise from wind turbines is that swishing. To some extent, it is unavoidable. It is the nature of the machine. You can get mechanical noise if there are faults, but we are mainly talking about aerodynamic noise, the swish. The recent designs of turbines have a better blade angle going into the air. It is like any newer, more modern machine; it would tend to be quieter than older machines. They have a better design. However, larger turbines are louder and have more low-frequency noise. So, the more modern ones are quieter, but the larger ones, of course, are going to be louder.
It is not a steady noise, like your fridge at home, and you may not notice it until it suddenly kicks off. A fridge makes is a steady noise and is not that noticeable. Wind turbine noise has a fluctuation. It goes up and down a little bit. The ETSU guidance, published in 1997, acknowledged there was some fluctuation, but bigger wind turbines have been found to have more fluctuations and more in the lower-frequency range.
The ETSU guidance relies very much on the British Standards Institution’s BS 4142, which says that more emphasis should be put on the fluctuations. If a noise is not steady, you have to account for that. It is likely to be more annoying if it fluctuates. I am talking about amplitude modulation, which is up and down – non-steady because it is not steady. The standard says to take account of that and add in another five decibels for the annoyance as it is not a steady noise. When the ETSU guidance was published in 1997, it did not recognise the degree of fluctuations that we now know the larger machines are capable of. ETSU is the assessment and rating of noise from wind turbines. Our planning and policy statement refers to ETSU.
The evidence base has expanded a lot since the ETSU guidelines were published in 1997. A lot more is known about wind turbine noise and annoyance. Also since 1997, the World Health Organization has reduced its recommended indoor night-time noise from 35 decibels to 30 decibels. They reckon that for people not to have their sleep disturbed, it should be 30 decibels.
The ETSU guidance talks a lot about the L90 measure. As I mentioned, that is not the average sound level, it is the lower sound level. ETSU uses L90, the lower level, for both turbine noise and background noise. That is very unusual. All the other guidance that I have read and all the other standards use LAeq. They all use the average; so this is quite unusual for ETSU. When the ETSU guidance was written, it was recommended that it should be reviewed within two years; however, it has not been reviewed. Some of the people who actually wrote the ETSU guidance have subsequently published a paper saying that it might underestimate the noise. So, the people who wrote the ETSU guidance have reservations and reckon that it needs to be updated in the light of current knowledge.
Basically, the reason I think that the ETSU guidance should be revised – apart from the fact that its authors think so – is that the quieter the environment, the more disturbing the noise is. So, it is not necessarily about the actual noise level; it is about the difference between the background noise – what you are used to – and the source noise. It is the difference between the background noise level and the source, not necessarily the absolute, noise level. So, something in the centre of Belfast may not be very annoying, but if it were in the countryside the exact same noise would be annoying. That is what the British standard says as well: it is the difference between the background noise and the source noise. ETSU refers to that; however, it then says that in low-noise environments you may not use that approach. So, I think that ETSU needs to be clarified: why it is usually the difference between the background noise and the actual wind noise, and why sometimes the background noise is not considered. That needs further explanation. ETSU needs to be updated with regard to the World Health Organization’s changes, and more consideration needs to be given to those fluctuations.
Let me turn to some particular issues which you asked me about. Anecdotally, I have heard from several sources, although I do not have evidence, that Northern Ireland is in receipt of older wind turbines, refurbished from other countries. Three academic and professional sources have told me that Northern Ireland is getting refurbished wind turbines. Obviously, those turbines do not benefit from the more recent designs and they may show signs of wear and tear. For example, the blade may have indentations, holes or wear which make it noisier. Apparently, some websites that market reconditioned turbines highlight Northern Ireland as a potential market. I query why such turbines, which are perhaps no longer acceptable in other countries, are acceptable here. Other industries have to show use of best available technology with regard to noise. With refurbished turbines in use, I would query whether we are getting the best technology as defined in the report. Also, with regard to noise, it is a defence to prove use of best practicable means. Again, I think it would be worth looking into the refurbished, reconditioned turbines.
You were asking me in my brief whether the developer should carry out ongoing noise monitoring. My report states that that would identify any increases in noise and any increases beyond what was anticipated. Such noise could be identified and remedied, so I recommend ongoing monitoring by the developer.
You also ask me about setting planning conditions. It is very common for environmental health to advise the Planning Service on planning conditions with regard to noise. There are model planning conditions for noise in guidance provided by the Institute of Acoustics. Use of that would be common.
You also asked me about the environmental health profession’s knowledge of acoustics and noise. My report says that there is a great deal of expertise in acoustics in Northern Ireland’s environmental health profession. Many of them have the postgraduate diploma in acoustics, are members of the Institute of Acoustics and sit on the institute’s advisory committees. However, even though there will be fewer and larger councils shortly in Northern Ireland, there is a considerable and time-consuming administrative and human resources burden due to commenting on planning applications on wind turbines. So, there is a burden on councils.
My report suggests that there should be a more strategic approach to wind turbine planning permission, rather than planning permission being granted on an ad hoc, case-by-case basis. There should be an overview and strategic approach to where we want turbines to be rather than those that pop up intermittently.
I think that we should refer to the Danish policy. In Denmark, there is the subsidy scheme for replacement of wind turbines as they become less efficient and, as I mentioned, noisier. Newer ones are less noisy. They replace wind turbines and have a replacement scheme. They are really going towards offshore, rather than onshore, wind turbines. They do acknowledge that there have been complaints in Denmark. Maybe we might not think that other countries complain about noise. They have a loss-of-value scheme for dwellings, so that, if your dwelling is badly affected by wind-turbine noise, there is a compensation scheme. There is an option to purchase at least 20%. So, if a wind turbine is being erected near your house, you have the option to purchase a portion of that turbine so that you will then have an economic interest in it. One of the reasons why people feel particularly aggrieved is when they feel that they have no control and that there is an injustice. We might benefit from the experiences of the Danish.
I was also asked to compare wind turbine noise to road traffic noise and other industrial noise. Wind turbine noise has been found to be more annoying than industrial and road traffic noise. At significant roads and industrial areas, the noise has to be mapped and action plans put in place. With road traffic noise, if a road is being significantly upgraded and your house is nearby, you can get money towards insulation and there is a compensation scheme in place. However, I would say that comparing wind turbine noise with industrial or road traffic noise is like apples and oranges because they are different characters. Road traffic noise tends to go down at night. Roads would not be as noisy at night. So, it is different.
In summary, the ETSU guidance actually permits louder noise at night than it does during the day. Again, anecdotally, I have been told that some operators actually increase their production of electricity at night when they are allowed to emit louder noise levels than during the day. That seems like another reason why the guidance could do with being reviewed and revised.