Report number: 2776.01 STERN WIND LTD PROPOSED ADDITIONAL WIND TURBINE T682A SCOVESTON PARK, STEYNTON, MILFORD HAVEN ASSESSMENT OF ENVIRONMENTAL NOISE Prepared for: Stern Wind Ltd c/o Planning Consultations 1 Melmount Park Strabane Co Tyrone BT82 9SU ACIA Engineering Acoustics 39 Garners Lane Stockport SK3 8SD 0161 487 2225 www.acia-acoustics.co.uk 2776.01 page 1 1. INTRODUCTION 1.1 Brief ACIA was commissioned by Stern Wind on behalf of the applicant to undertake a study of the noise likely to arise from the installation of a second wind turbine at Scoveston Park, Steynton, Milford Haven, Pembrokeshire. Planning permission was given by Pembrokeshire County Council on 30 May 2013 for a turbine at Scoveston Park (reference 13/0222/PA). No background noise survey was undertaken in connection with that planning application, and therefore none was required for the present application. Preliminary calculations were made which indicated that the noise immission levels at neighbouring non-involved residential properties, as a results of the proposed additional turbine, were likely to remain below 35dB LA90,10min. This would allow the use of the ‘simplified’ noise assessment methodology in ETSU-R-97, provided that the cumulative effect of all wind turbines in the area did not cause a breach of Condition 6 of the existing consent: this sets a noise limit of 38dB LA90,10min. 1.2 Methodology In view of the preliminary results, the levels of noise likely to occur at local residential properties as a result of the operation of the proposed turbine were calculated according to the usual best practice applicable to wind energy developments in Wales. The environmental implications were then considered at each of the nearest potentially noise-sensitive properties. The results are assessed against the guidelines available for wind energy developments, which are contained in Technical Advice Note 8: Planning for Renewable Energy (TAN 8) dating from July 2005. This recommends the use of the ETSU-R-97 report The Assessment and Rating of Noise from Wind Farms and the latest Onshore wind energy planning conditions guidance note (Renewables Advisory Board and the Department for Business, Enterprise and Regulatory Reform, BERR). The March/April 2009 issue of Acoustics Bulletin contained an article describing an agreement among a number of acousticians with considerable experience in the wind energy field, and this article made a number of recommendations for the interpretation of ETSU-R-97 in the light of recent knowledge. The Institute of Acoustics’ working group published the Good Practice Guide to the Application of ETSU-R-97 for the Assessment and Rating of Wind Turbine Noise in May 2013, with six supplementary guidance notes following in 2014. These documents confirmed many of the recommendations from the Acoustics Bulletin article and provided some additional details. It is the view of the Welsh Assembly Government policy that this Good Practice Guide represents guidance on best practice, and that it should be followed in carrying out wind turbine noise assessments. The following assessment was therefore carried out in accordance with the Good Practice Guide. ACIA Engineering Acoustics 2776.01 page 2 2. RELEVANT GUIDANCE AND STANDARDS 2.1 Government policy 2.1.1 Planning Policy Wales The latest overarching planning policy document is Planning Policy Wales, Edition 5, November 2012. In Chapter 12 of this document, which covers infrastructure and services, it is the stated policy of the Welsh Government that the need for wind energy is a key part of meeting its vision for future renewable electricity production as set out in the Energy Policy Statement (2010) and this should be taken into account by decision makers when determining such applications. The impacts from renewable energy development will vary depending on their type, location and scale. For planning purposes a development of between 50kW and 5MW falls into the ‘sub local authority’ scale for planning purposes. Specific guidance on renewables is provided in TAN 8: this is discussed in detail below. 2.1.2 TAN 8 This Technical Advice note includes at Annex C, paragraphs 2.14 to 2.16, a description of the noise emitted by wind turbines and how it varies with wind speed. It states that the report The Assessment and Rating of Noise from Wind Farms (ETSU-R-97) describes a framework for the measurement of wind farm noise and gives indicative noise levels calculated to offer a reasonable degree of protection to wind farm neighbours, without placing unreasonable restrictions on wind farm development or adding unduly to the costs and administrative burdens on wind energy developers or planning authorities. The recommendations of the cross-interest Noise Working Group which prepared the report is regarded as relevant guidance on good practice. TAN 8 Annex C also says (paragraph 2.17) that there is no evidence that ground- transmitted low frequency noise from wind turbines is at a sufficient level to be harmful to human health. 2.2 Guidance now superseded 2.2.1 BS.4142:1997 The usual basis for assessing noise of industrial origin throughout the UK until very recently was BS.4142:1997, which called for a comparison of the ‘new’ noise with the pre-existing LA90. The standard was extensively revised and published in November 2014. The basic premise of the standard has not changed over the years, but there were always problems with its direct application to wind energy developments because the conditions stipulated by the 1997 standard were often difficult to satisfy. The latest version states at paragraph 1.3(h) that noise sources falling within the scopes of other standards or guidance should not be assessed using BS.4142:2014. ETSU-R-97 and the Institute of Acoustics Good Practice Guide constitute such guidance. ACIA Engineering Acoustics 2776.01 page 3 2.2.2 Renewables Advisory Board and BERR In October 2007 a report ‘Onshore wind energy planning conditions: Guidance note’ was produced for the Renewables Advisory Board and the Department for Business, Enterprise and Regulatory Reform by TNEI Services Ltd. The purpose of the document was to provide advice on the appropriate types of planning condition relevant to wind energy development. It incorporated information already present within existing planning guidance, provided additional advice regarding the use of planning conditions, and outlined generic conditions for use in wind energy developments. It was aimed at Local Planning Authorities, statutory consultees, objector groups, potential wind applicants and other stakeholders. As far as noise was concerned, the BERR guidance reproduced the relevant parts of ETSU- R-97, further strengthening the view that the latter was entirely appropriate for this type of development. 2.3 ETSU-R-97 2.3.1 Background noise Developments of this type in Wales are to be assessed using the DTI Energy Technology Support Unit’s report dating from 1996, ETSU-R-97. The report was published as a result of the deliberations of the Department of Trade and Industry’s wind turbine noise working group, set up to provide guidance to the industry and planning authorities. At the time (in the early 1990s), it was recognised that the application of existing guidance posed difficulties when applied to wind energy developments. A major concern about the application of BS.4142 as it then existed, and the treatment of industrial noise in the environment generally, was that it had always been assumed that the worst case for noise emission propagation from a 24-hour industrial operation would occur at night, in still conditions. This was emphatically not the case for wind turbine noise, because in still wind conditions the turbines would not operate. The working group consisted of wind farm developers, DTI staff, environmental health officers and independent noise consultants. The report remained within the spirit of BS.4142 whilst dealing with the practical difficulties of determining the underlying background noise level and the setting of noise limits in very quiet rural areas. It was originally intended that the guidance would be reviewed after ten years had elapsed: a recently-published review of planning conditions for renewable energy generally (which was prepared for RAB/BERR — see below) has confirmed the continuing validity of the recommendations. It remains Welsh Government policy that wind energy projects should be assessed using ETSU-R- 97 as best practice guidance. The report describes a framework for the measurement of wind turbine noise and indicates desirable noise levels, so that without placing unreasonable restrictions on wind power developments, neighbouring residential properties can gain protection from excessive noise. A primary objective of the report is to suggest noise limits in a form suitable for adoption as planning conditions. The Noise Working Group that produced the report considered that absolute noise limits regardless of wind speeds are not suited to wind farms in the UK, and that it is more appropriate in the majority of cases to set noise limits relative to background noise. The background noise levels are to be measured over a range of wind speeds so that the impact of turbine noise, which is also wind-speed dependant, can be evaluated. ACIA Engineering Acoustics 2776.01 page 4 One of the most important recommendations in the ETSU-R-97 report is that the statistical index LA90,10min should be used for both the background noise and the wind turbine noise. This allows reliable measurements to be made without them being corrupted by louder, transitory noise events from other sources. The report notes that for the typical wind energy scheme, the LA90,10min is between 1.5 and 2.5 dB lower than the LAeq over the same measurement period. This is worthy of note because for conventional noise measurements in the environment, the LAeq index is generally regarded as the most appropriate descriptor, and it is normal practice to use it when noise limits are being set.