No significant construction or operational vibration impacts are expected.

Transcription

1 8 NOISE AND VIBRATION 8.1 SUMMARY OF RESIDUAL IMPACTS impacts for the construction and operation of the proposed CCGT power plant development are expected as these will be mitigated through design and planning conditions as appropriate. A temporary residual noise impact as a result of road traffic noise from personnel vehicles associated with the construction of the scheme is expected on residents living alongside the A48. This will only occur in the hours when construction personnel will be travelling to and from site, during the peak month of the 30 month Stage 1 construction period. During commissioning there will be short periods between the hours of 09:00hrs and 17:30hrs when pipelines will be subjected to purging flows and safety valves tested. These operations are short-term in duration, but can cause high levels of noise and therefore result in temporary residual noise impacts. These activities will take place occasionally and will last only a few hours at a time. No significant construction or operational vibration impacts are expected. 8.2 INTRODUCTION This chapter considers the potential for noise and vibration impacts associated with the construction and operation of the proposed power station at the Baglan Bay Energy Park. The site is adjacent to the GE power station and the M4 motorway. The proposed scheme will introduce a new and permanent source of noise in the area. 8.3 LEGISLATION AND POLICY REVIEW The aim of noise policy within Wales is to protect individuals from excessive noise levels both in the workplace and when at home. It has been recognised that noise can cause annoyance and can lead to sleep disturbance and potentially other adverse health effects. Legislation has aimed to address this. Regulations, mainly at EU level, have set maximum sound levels for vehicles, aeroplanes and machines. More recently the European Commission has requested mapping of noise levels and the development of Action Plans to address noise problems where necessary, including preservation of quiet areas. At national level, the Department of Environment, Food and Rural Affairs (DEFRA) has been developing an Ambient Noise Strategy giving policy guidance on transportation and industrial noise. Planning Guidance (TAN 11) has also been important in promoting ways of reducing noise problems in the future. Some local 8-1

2 authorities also produce their own local planning guidance as part of their development plans. Relevant policies are discussed in greater detail in Section 8.4 below. 8.4 ASSESSMENT SCOPE AND METHODOLOGY Introduction The approach to this assessment has been discussed and agreed in consultation with Neath and Port Talbot County Borough Council. The scope of this assessment, and the assessment methodology and criteria are discussed below Scope of Assessment The assessment included the following tasks: defining noise sensitive receptors (NSRs) in consultation with NPTCBC; defining the baseline noise environment by measurement at representative NSRs; assessing construction noise and vibration impacts at representative NSRs; assessing road traffic noise impacts from construction and operation; and defining acceptable operational noise and vibration levels for the proposed development Construction Assessment Methodology and Criteria Advice and guidelines to local planning authorities and developers on construction noise in the UK can be found in British Standard BS 5228 (1) and Advisory Leaflet (AL) 72 (2). AL 72 is out of print, but remains as a paper giving guidance on acceptable levels of construction noise. BS 5228 Part 1 does not specify suitable daytime noise levels from construction sites, but lists a number of factors that might affect the acceptability of noise and vibration from construction sites. These factors are: (1) British Standard BS 5228: 1997 Noise control on construction and open sites. BSI (2) Advisory Leaflet 72. Noise control on building sites. Department of the Environment

3 site location; existing ambient noise levels; duration of site operations; hours of work; attitude to site operator; and noise and vibration characteristics of the work. Although BS 5228 does not propose noise standards for daytime periods, it suggests that acceptable noise levels in the evening ( hours) may need to be 10 db(a) lower than daytime levels. AL 72 gives advice on preferred maximum levels of construction site noise at residential locations during daytime hours ( hours). Since the criterion of speech interference forms the basis of the recommendations within AL 72, they can be taken as applicable to commercial buildings as well as residential properties. The leaflet states that the noise level outside the nearest occupied room should not exceed: 75 db(a) in urban areas near to main roads in heavy industrial areas; or 70 db(a) in rural, suburban and urban areas away from main road traffic and industrial noise. These levels are generally taken as being facade L Aeq, period (1) and will be used to assess potential construction noise impacts. Local authorities have powers under the Control of Pollution Act 1974 to control noise from construction sites. These powers do not refer to fixed noise limits but instead allow for the enforcement of best practicable means (2) to reduce or counteract the effects of the noise. It is assumed that the construction work will take place over a five day working week, with the maximum working hours of 0700 to 1900 hours. A Code of Construction Practice () will set working hours and noise control measures, and will be agreed with NPTCBC prior to construction work commencing Operational Noise Assessment Methodology and Criteria Overview Noise from developments is assessed in two ways: by comparing the predicted level of noise from the development against absolute noise standards, such as those that indicate likely (1) LAeq is defined as the notional steady sound level which, over a stated period of time, would contain the same amount of acoustical energy as the A-weighted fluctuating sound measured over that period. (2) Defined in Section 72 of the Control of Pollution Act

4 annoyance and/or disturbance of everyday activities; and/or by considering the change in ambient noise that will occur with the development in operation. Criteria which may be applicable for operational noise from the proposed development, including road traffic noise are discussed below. Technical Advice Note (TAN) 11 Technical Advice Note (TAN) 11 (1) provides guidance to local authorities on how the planning system can be used to minimise the adverse impact of noise without placing unreasonable restrictions on development or adding unduly to the costs and administrative burdens of business. It outlines some of the main considerations which local planning authorities should take into account when determining planning applications for development which will either generate noise or be exposed to existing noise sources. TAN 11 also makes reference to other guidance and criteria applicable for different sources of noise such as industrial and commercial developments, roads and railways. TAN 11 states that BS 4142 (2) is the most appropriate methodology to assess noise from industrial developments and from fixed plant associated with the proposed developments. British Standard BS 4142 The test that is generally applied to determining the level of noise of an industrial nature likely to give rise to complaints from persons living in the vicinity is given in British Standard BS BS 4142 describes a method for determining industrial and background noise levels outside residential buildings and for assessing whether the industrial noise is likely to give rise to complaints from the occupants. The BS 4142 assessment methodology involves the following procedure: the background (L A90) noise level (BNL) in the absence of the noise source is measured outside the noise-sensitive receptor; the noise level from the source is then quantified, by prediction or measurement, at a noise sensitive receptor as an L Aeq (using the procedures set out in the standard); (1) Planning Guidance (Wales). Technical Advice Note 11, (2) British Standard BS 4142: 1997 'Method for Rating industrial noise affecting mixed residential and industrial areas' 8-4

5 the noise level is corrected, if appropriate, for duration and character, with the corrected noise level being termed the rating level and expressed as an L Aeq; and the rating level is then compared with the BNL (L A90) for the area. The interpretation of the difference between the rating level and the BNL is shown in Table 8.1 below. Table 8.1 Interpretation of Noise Level Difference Difference in Noise Level (db) Around +10 Around +5 More than 10 Significance Complaints are likely Marginal Positive indication that complaints are unlikely BS 4142 requires that daytime assessments are based on the highest L Aeq from the noise source over a period of 1 hour, while at night an assessment period of 5 minutes is specified Road Traffic Noise The proposed development may alter the traffic flows on the local highways leading to changes in road traffic noise. The road traffic noise assessment takes into consideration the following guidance as appropriate: DMRB (1) to identify where changes in road traffic will require a more detailed assessment; and CRTN (2) to assess the actual change in road traffic noise as a result of the project. An increase in traffic flow of 25% (or reduction by 20%) is generally needed to increase noise levels by 1 db(a). A change of 1 db(a) is only perceptible in controlled conditions, and a change of 3 db(a) is generally accepted as the minimum perceptible under normal conditions. For heavy goods vehicles an increase of around 5% is generally needed to increase noise levels by 1 db(a). Flow changes of this size are not expected to give rise to perceptible noise changes under normal listening conditions and have been adopted as the scoping criterion for road traffic noise. These standards apply to permanent noise changes and higher changes are likely to be acceptable during construction. (1) Design Manual for Roads and Bridges (DMRB). Volume 11, Section 3, Part 7 'Traffic Noise and Vibration' (2) Department of Transport / Welsh Office Memorandum 'Calculation of Road Traffic Noise' (CRTN),

6 8.4.6 Vibration Assessment Criteria Human Exposure The assessment of vibration follows the guidance set out in British Standard BS 6472 (1). This standard provides a method to assess disturbance from vibration. The vibration dose value (VDV) levels, given in BS 6472 at or below which the probability of adverse comment is low are as follows: daytime ( hours): 0.4 m/s 1.75 ; and night-time ( hours): 0.13 m/s Building Damage Arising from Vibration British Standard BS 7385 (part 2) (2) provides vibration criteria relating to building damage and advice on acceptable levels of vibration in structures. Limits for primarily transient vibration (eg from piling works or train passby) above which cosmetic damage could occur are as follows: reinforced or framed buildings: 50 mm/s PPV; or un-reinforced or light framed buildings: 15 mm/s PPV. 8.5 BASELINE CONDITIONS Noise Sensitive Receptors The site of the proposed CCGT power plant development is located to the north west of the Baglan Bay Energy Park and adjacent to the existing GE power station. The village of Baglan is located on a hill to the north east of the M4 motorway, overlooking the site. The A48 and M4 separate the site and the village of Baglan. A full description of the development is given in Chapter 2. The site location, NSRs and noise measurement locations are illustrated in Figure 8.1. A description of the NSRs and noise measurement locations are given below. Location 1: Brahams Avenue. Representative of residential properties in Sandfields to the south of the site, approximately 465 m from the closest site boundary. (1) BS 6472: 1992 'Guide to Evaluation of human exposure to vibration in buildings (1 Hz to 80 Hz). (2) BS : 1993 Evaluation and measurement for vibration in buildings Part 2: Guide to damage levels from groundborne vibration. 8-6

7 Location 2: Affendale. Representative of a recent residential development situated between Sandfields and Baglan Moors to the south of the site, approximately 610 m from the closest site boundary. Location 3: Church Street. Representative of properties in Briton Ferry and Llansawel to the north east of the site, approximately 320 m from the closest site boundary (re-routed pipe), and 1495 m from the main works (CCGT plant). There is also a travellers site at this location which may experience potential noise impacts associated with the construction of the water works and re-routing of the water pipe. Location 4: Sunny Mount. Representative of properties to the east of the site, located on the far side of the M4 motorway, approximately 1120 m from the closest site boundary Baseline Noise Environment Measurements were taken in accordance with BS 4142 using a Type 1 sound level meter placed on a tripod at a height of 1.5m, and calibrated prior to use. No significant (± 0.5dB) calibration drift was noted. The surveys were undertaken during the weekends of May 25 th and June 2 nd, Full details of the survey and a glossary of acoustic terms are included in Annex B. Ambient noise levels at each location were found to vary, and in general the lowest ambient levels recorded in each time period are used in the assessment. A summary of the measured baseline noise levels are presented in Table 8.2 below. Table 8.2 Summary of Measured Baseline Noise Levels (free-field), db Measurement Location (See Figure 8.1) Daytime (1) L Aeq, 10 mins Sound Pressure Level (db) Night-time (2) L Amax, range of 10 min samples L Aeq, 10 mins 1 - Brahams Avenue Affendale Church Street Sunny Mount Ambient noise at Brahams Avenue and Affendale consisted of road traffic noise from local roads, the A48 and M4, and operational noise from the GE power station. Ambient noise at Church Street and Sunny Mount was dominated by road traffic noise from the A48 and the M4 along with operational noise from the GE power station, perceptible during gaps in the traffic. (1) Daytime is defined as hours (2) Night time is defined as hours 8-7

8 3! (! ( KEY:! ( CLIENT: Monitoring Locations Red Line Boundary 0. Metres APCL! ( SIZE: 2 A4 ERM Llandarcy House 11A The Courtyard Llandarcy Swansea Bay, SA10 6EJ Tel: Fax: SOURCE: Reproduced from Ordnance Survey digital map data. Crown copyright, All rights reserved License number PROJECTION: British National Grid 4 TITLE: Figure 8.1 Noise Monitoring Locations DATE: 29/05/2008 CHECKED: SD PROJECT: DRAWN: CO SCALE: As Scale Bar DRAWING: APPROVED: SD Noise.mxd REV: 1 File: BaglanBayGIS\mxds\NewB oundary_es\noise.mxd! (

9 8.6 POTENTIAL NOISE IMPACTS Predicted Construction Noise Levels Construction noise will arise from on-site construction and from plant and vehicles on the site and on local roads. The anticipated level of construction noise during each phase of the project will vary depending on the activity taking place, distance between the works and NSR and any local noise screening or ground attenuation effects. There will be a range of noise emissions during the works, from particularly noisy (but usually short-term) activities such as piling and foundation works to relatively quiet works, such as the final fit-out and completion of buildings where heavy machinery is not usually required and some works can be carried out within the building. Detailed construction plant information is unavailable at this stage. However, in the absence of this information, generic plant levels from comparable developments have been used to assess potential construction noise impacts. The noisiest construction phases are assessed as follows: 1. Site preparation including earthworks estimated duration 6 months, to commence in Summer/Autumn 2011, with a total equivalent sound pressure level of L Aeq 89 db at 10m. Noise from the site preparation phase of the works will be experienced at all NSRs. 2. Foundation works estimated duration 6 months, to commence in autumn 2011 with a total equivalent sound pressure level of L Aeq 88 db at 10m. Noise from foundation works phase of the works will be experienced at all NSRs. 3. Piling activities associated with the water works and pipeline estimated duration 3 months, with a total equivalent sound pressure level of L Aeq 88 db at 10m. Sheet piling phase will be necessary in the vicinity of all NSRs, and particularly those at Church Street for works associated with the water works / pipeline re-routing. 4. Building and structural works for Stage 1 of construction (estimated duration 30 months) will commence in spring 2011, with a total equivalent sound pressure level of L Aeq 85 db at 10m. An 18 month construction period will follow during 2015/2016 to complete Stage 2. Noise from the building and structural phase of the works will be experienced at all NSRs. 8-9

10 Noise level data for typical construction activities associated with each of the four work phases outlined above were obtained from a database (1) and from experience of similar projects. These levels form the basis of the construction noise impact assessment. Predicted construction noise levels are presented in Table 8.3. They are based on the distance between the nearest receptor and the closest site boundary without mitigation. The calculations have also assumed that sheet piling will take place at the water works and pipeline re-routing in proximity of Church Street. These are conservative assumptions, and the predicted construction noise levels will be over-estimated. This scenario therefore presents the worst-case construction noise levels. Table 8.3 Worst Case Construction Noise Levels (without Mitigation) Receptor (See Figure 8.1) Approx. distance to nearest site boundary (m) Indicative construction noise levels, façade L Aeq, T (db) Site Foundation Piling Building preparation works structural works Construction Noise Criterion Level, db Significance of Impact 1. Brahms None Avenue 2. Affendale None 3. Church None Street 4. Sunny Mount None These indicative noise levels at the receptors are based on construction works taking place at the closest work site boundary. These situations are likely to occur only for short periods of time in each instance, and in most cases, the works will be at a greater distance than those indicated. Although the calculated noise levels are for the worst-case construction activity, the predicted construction noise levels fall well below the daytime noise criterion. In two of the four locations the existing daytime noise levels (reported in Table 8.2) are greater than the predicted worst-case construction noise levels. The traveller s site situated adjacent to Church Street will not be subject to significant noise impacts from the construction operations associated with works to the water pipe. However piling, and other works may be audible Construction Traffic Chapter 5 (Traffic and Transport) identifies that movements of private vehicles associated with the construction workers will give rise to a (1) DEFRA (2005) 'Update of Noise Database for Prediction of Noise on Construction and Open Sites'. 8-10

11 substantial percentage increases in the peak month during the early morning ( ) and evening ( ) periods only. This will result in a temporary noise impact from personnel vehicles on residents living alongside the A48 in Baglan during these hours, and during the peak month of the 30 month Stage 1 construction period only (ie month 20). However, these increases appear when the road network will be substantially under capacity. During the peak month, there will be up to 90 HGV movements per day between 0700 and At all times outside of the peak construction month the generated HGV traffic is expected to be less than 90 per day. This is not considered significant, and no construction traffic noise impacts from HGVs are expected. Mitigation measures for road traffic noise are discussed in Chapter 5 (Traffic and Transport) Commissioning Noise During commissioning there will be short periods between the hours of 09:00hrs and 17:30hrs when pipelines will be subjected to purging flows and safety valves tested. These operations are short-term in duration, but can cause high levels of noise. Residents will be informed a number of days before the event. The timing of these events are difficult to forecast however it is anticipated that the steam blowing activities will take place occasionally and will last only a few hours at a time. Commissioning is due to take place for Stage 1, autumn 2013 and for Stage 2 in autumn Operational Noise Operational noise will occur as a result of the operation of plant and from road traffic associated with the project. At this stage, detailed plant specification is unavailable to predict operational noise levels at the nearest NSRs. However, in the absence of predicted noise levels, and following consultation with NPTCBC, a suitable noise design criterion for the proposed development has been established by utilising the methodology outlined in BS BS 4142 indicates that where the predicted noise level is 10 db greater than the background level, then this is a positive indication that complaints are likely. An increase of around 5 db is of marginal significance, and a predicted level of 10 db less than the background noise level is a positive indication that complaints are unlikely. 8-11

12 BS 4142 also suggests that a penalty of 5 db should be applied when rating the likelihood of complaints from a noise source that has discrete tonal, impulsive or irregular character. The operation of the plant will largely be a continuous process, with numerous sources of noise including fans and cooling equipment which may generate tonal noise. A character penalty of 5 db has therefore been included to the plant noise in determining the rating level specified in BS4142. In the absence of source data to calculate operational noise emissions, a noise design criterion is established for total noise emission of plant associated with the project. This is so that it does not exceed the BS 4142 target level set for each of the four NSRs identified in Figure 8.1. By ensuring that the plant noise level is no higher than the minimum background L A90 noise level at a given receptor, it would avoid the rating level exceeding the background noise by more than 5 db(a), which in turn avoids a noise level of more than marginal significance according to BS The BS 4142 target level at each receptor is given in Table 8.4 below and is applicable for night-time, which is the most sensitive time period. Table 8.4 Summary of Operational Noise Criteria (Night Time) Receptor (See Figure 8.1) Distance to closest site Night-time Minimum Baseline Noise Level Target Level at the receptor boundary (m) L Aeq,period (db) L A90,period (db) L Aeq,5-min (db) 1. Brahms Avenue Affendale Church Street 320 (1) Sunny Mount (1) Church Street is 320 m from the water works/pipeline route, but 1495 m from the main development. Compliance with the above criteria will ensure that significant operational impacts are avoided Operational Traffic Chapter 5 (Traffic and Transport) reports a maximum of 80 movements over a 24 hour period to and from the site. Throughout the operational period there will be negligible numbers of HGVs accessing the site. Such changes are not significant compared to the baseline traffic flow, and no operational traffic noise impacts are expected. 8-12

13 8.7 POTENTIAL VIBRATION IMPACTS Vibration during Construction Measurements of vibration from construction plant have shown that, even from percussive piling equipment, levels typically fall to imperceptibility beyond approximately 100 m from the vibration source. Imperceptible levels are reached at much smaller distances from other sources of vibration, such as construction plant. There are no NSRs within 100 m of potential sources of vibration associated with construction works. No significant construction vibration impacts are expected Vibration during Operation The design of the power station will ensure that vibration will be imperceptible beyond the site boundary. No significant vibration impacts are expected to occur during operation. 8.8 CUMULATIVE IMPACTS Potential cumulative impacts from this development may arise from the operation of the project. The baseline noise measurements have taken account of noise from the existing power station, and the operational noise levels of the proposed power station outlined in Table 8.4 will ensure that there will be a non significant increase in operational noise. Cumulative impacts from road traffic noise (personnel vehicles) may occur during the peak month of the construction only. 8.9 MITIGATION Construction Construction works are expected to be undertaken during daytime hours. However, there may be occasions, for example delivery of abnormal loads, which may require evening or night-time construction. Should this be necessary, the mitigation measures below will be included in a Code of Construction Practice () adopted by the project to control noise impacts. The will be implemented during the works and take account of the following: the proper use of such plant with respect to minimising noise emissions; the proper maintenance of plant, including plant housings and silencers; 8-13

14 the selection of inherently quiet plant, and use of enclosures and screens around noisy fixed plant. Site hoardings can also provide some benefit from acoustic screening provided they are of suitable construction and properly installed; placing noisy plant as far as possible from sensitive receptors; informing neighbouring building occupants and the local Environmental Health Department when particularly noisy operations are planned; and Operation identifying a Baglan Bay Energy Park Project site liaison officer to deal with noise and other environmental matters. Furthermore, the Contractor will adhere to the codes of practice for construction working and piling outlined in BS 5228 parts 1 and 4. This advice will be incorporated within the for minimising noise emissions from the site. During operation, mitigation measures will include the following noise control methods: Selection of quiet equipment and engineering solutions to reduce noise at source and improve the sound insulation of buildings and enclosures housing noisy equipment to ensure that operational noise achieves the levels outlined in Table 8.4. Ensuring the proposed power plant site layout is optimised to provide adequate distance between particular sources of noise and noise sensitive buildings or areas and from using screening by natural and engineered barriers and other buildings, as necessary. With regard to engineering solutions, significant attenuation can be achieved through established noise control packages, and given the separation of the plant from NSRs, screening and other factors, it is expected that the BS 4142 target levels outlined in Table 8.4 can be met CONCLUSIONS AND SUMMARY OF RESIDUAL IMPACTS impacts for the construction and operation of the development are expected as these can be mitigated through design and planning conditions as appropriate. A temporary residual noise impact as a result of road traffic noise from personnel vehicles associated with the construction of the scheme is expected on residents living alongside the A48. This will only occur in the 8-14

15 hours when construction personnel will be travelling to and from site, during the peak month of the 30 month Stage 1 construction period. During commissioning there will be short periods between the hours of 09:00hrs and 17:30hrs when pipelines will be subjected to purging flows and safety valves tested. These operations are short-term in duration, but can cause high levels of noise and therefore result in temporary residual noise impacts. These activities will take place occasionally and will last only a few hours at a time. No significant construction or operational vibration impacts are expected. A summary of all impacts and mitigation measures is detailed in Table 8.5 below. 8-15

16 Table 8.5 Summary of Impacts and Mitigation Impact Type Noise and Vibration Key Potential Impacts (without mitigation) Impacts on noise sensitive receptors resulting from construction. Mitigation Residual Impact Means by which mitigation will be delivered Construction works are expected to be undertaken during daytime hours. However, there may be occasions, for example delivery of abnormal loads, which may require evening or night-time construction Should this be necessary, the mitigation measures below will be included in a Construction HSSE Plan adopted by the project to control noise impacts. The HSSE Plan will be implemented during the works and take account of the following: impacts predicted. the proper use of such plant with respect to minimising noise emissions; impacts predicted. the proper maintenance of plant, including plant housings and silencers; impacts predicted. the selection of inherently quiet plant, and use of enclosures and screens around noisy fixed plant. Site hoardings can also provide some benefit from acoustic screening provided they are of suitable construction and properly installed; impacts predicted. placing noisy plant as far as possible from sensitive receptors; impacts predicted.

17 Impact Type Key Potential Impacts (without mitigation) Mitigation Residual Impact Means by which mitigation will be delivered informing neighbouring building occupants and the local Environmental Health Department when particularly noisy operations are planned; and impacts predicted. identifying a Baglan Bay Energy Park Project site liaison officer to deal with noise and other environmental matters. impacts predicted. The Contractor will adhere to the codes of practice for construction working and piling outlined in BS 5228 parts 1 and 4. This advice will be incorporated within the HSSE Plan for minimising noise emissions from the site. impacts predicted. Noise and Vibration Impacts on noise sensitive receptors resulting from Operation Selection of quiet equipment and engineering solutions to reduce noise at source and improve the sound insulation of buildings and enclosures housing noisy equipment and operations, including design measures to ensure that operational noise meets the levels outlined in Table 8.4. impacts predicted. Ensuring the proposed CCGT power station site layout is optimised to provide adequate distance between particular sources of noise and noise sensitive buildings or areas and from using screening by natural and engineered barriers and other buildings, as necessary. impacts predicted With regard to engineering solutions, significant attenuation can be achieved through established noise control packages, and given the separation of the plant from NSRs, screening and other factors, it is expected that the BS 4142 target levels outlined in Table 8.4 can be met. impacts predicted

18 Impact Type Noise and Vibration Key Potential Impacts (without mitigation) Impacts on noise sensitive receptors resulting from Construction Traffic Mitigation Residual Impact Means by which mitigation will be delivered Wherever practical, deliveries of abnormal loads will be made outside of peak hours and where appropriate during the night. Temporary residual noise impact expected for the peak month of construction. Construction vehicles will abide by the identified construction route. Temporary residual noise impact expected for the peak month of construction. Materials and equipment will be stored securely on site to minimise unnecessary traffic movements. Temporary residual noise impact expected for the peak month of construction.