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Appendix 1

APPENDIX 19 Outline Noise Impact Assessment - Proposed residential development at land between St Christopher’s Drive and A605 Oundle Bypass, Oundle, November 2017, Spectrum Acoustics Consultants

www.spect rumacoust i c .com

Report ref. MM588/17180/Rev. 1 Issued to Persimmon - Charles Church Prepared by

Consultant

Version Remarks Date

Rev. 0 Issued for comment 27.11.17

Rev. 1 Updated to include additional information request by the EHO 07.06.19

Proposed residential development at land between St Christopher’s Drive and A605 Oundle Bypass, Oundle

Outline Noise Impact Assessment

SPECTRUM ACOUSTIC CONSULTANTS TELEPHONE +44 (0)1767 318871 (HEAD OFFICE) +44 (0)1257 473242 (WIGAN)

SECTION TITLE PAGE

1. INTRODUCTION ........................................................................................... 1

2. SITE DESCRIPTION AND PROPOSALS ............................................................. 1

3. GUIDELINES FOR ACCEPTABILITY ................................................................. 1

3.1 NOISE POLICY GUIDELINES - NATIONAL PLANNING POLICY FRAMEWORK (NPPF) ............................. 1 3.2 BS 8233:2014 AND WHO ....................................................................................................... 3

4. AMBIENT NOISE SURVEY .............................................................................. 5

4.1 SURVEY DATE, LOCATION AND EQUIPMENT .................................................................................. 5 4.2 RESULTS ................................................................................................................................ 5

5. ASSESSMENT OF NOISE AT PROPOSED RESIDENCES ...................................... 7

5.1 NOISE PREDICTION MODEL ........................................................................................................ 7 5.2 NOTES ON ACOUSTIC DESIGN .................................................................................................... 7

6. PROPOSED MITIGATION MEASURES ............................................................ 12

6.1 ACOUSTIC FENCE ................................................................................................................... 12 6.2 FAÇADE ACOUSTIC SPECIFICATION ........................................................................................... 13

7. CONCLUSION ............................................................................................ 13

APPENDIX A: Site location plan showing measurement positions

APPENDIX B: Chart showing measured noise levels

APPENDIX C: Site location plan showing recommended noise barrier location

APPENDIX D: Contour plots showing noise across the site

APPENDIX E: Calculations of intrusive noise

SPECTRUM ACOUSTIC CONSULTANTS

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1. INTRODUCTION Persimmon – Charles Church (Persimmon) are seeking outline planning permission for a new residential development on land between St Christopher’s Drive and A605 Oundle Bypass, Oundle Northamptonshire. The site is currently a green field site and the proposal is for up to 100 new properties. Persimmon are seeking outline planning permission for the proposal from East Northamptonshire Council following the refusal of an earlier outline application and the dismissal of a subsequent appeal. Spectrum Acoustic Consultants have been engaged by Persimmon to carry out an investigation of the noise environment at the site and to provide an outline Noise Impact Assessment report for submission with the outline planning application. The primary intention of this report is to assess the potential for adverse effects as a result of noise on a proposed residential development at the site and to determine whether the outline proposals are conducive to a development with an acceptable level of acoustic amenity. Following the initial submission of this report and a pre-application consultation with the Local Authority, the Environmental Protection Officer has provide comments and requested additional information on how acoustic considerations have been factored in to the design progress. Accordingly, this report has been amended to include updated modelling results as well as additional commentary and discussion to address the points raised by the Local Authority.

2. SITE DESCRIPTION AND PROPOSALS The development site is located between St Christopher’s Drive and A605 Oundle Bypass, Oundle Northamptonshire. The site is a green field site which lies on the west side of the A605, to the east of Oundle. Just beyond the east boundary of site runs the A605, with an area of vegetation separating the majority of the site from the road. The A605 is a busy single lane bypass with a speed limit of 60 mph. An existing residential area is located to the north west of the site and Prince William Secondary School is located to the south west. Playing fields for the school adjoin the southern site boundary. To the east, beyond the A605 are open fields. To the north, adjoining the northern corner of the site is a commercial/industrial area. The nearest unit to the site is currently occupied by “Hutchinson’s”, a crop production specialist. A site location plan is included in Appendix A. Detailed layout plans have not yet been developed for the site as the proposal is in outline, however since Rev. 0 of this report was issued, initial proposals have now been developed. Persimmon are seeking permission for up to 100 dwellings on site and initial layouts show 100 dwellings. 92 of the 100 dwellings included in the indicative layout are 2 storey houses. There are also two 2-storey blocks containing 4 apartments each.

3. GUIDELINES FOR ACCEPTABILITY 3.1 NOISE POLICY GUIDELINES - NATIONAL PLANNING POLICY FRAMEWORK (NPPF)

The National Planning Policy Framework (NPPF) sets out the government’s guidance for local planning authorities and planning application decision-takers.


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It says that the planning system should contribute to and enhance the environment by (among other things) preventing development from contributing to, being put at risk from, or being adversely affected by unacceptable levels of noise pollution. (Para. 109) Paragraph 123 states that planning policies and decisions should aim to: • Avoid noise from giving rise to significant adverse impacts on health and quality of life as a result of

new development;

• Mitigate and reduce to a minimum other adverse impacts on health and quality of life arising from noise from new development, including through the use of conditions;

• Recognise that development will often create some noise and existing businesses wanting to develop in continuance of their business should not have unreasonable restrictions put on them because of changes in nearby land uses since they were established; and

• Identify and protect areas of tranquillity which have remained relatively undisturbed by noise and are prized for their recreational and amenity value for this reason.”

The NPPF refers to the Noise Policy Statement for England (NPSE) which sets out the long term vision of Government noise policy as follows: Promote good health and a good quality of life through the effective management of noise within the context of Government policy on sustainable development. The NPSE aims to clarify the principles and aims in existing policy documents, legislation and guidance that relate to noise. Its noise policy aims are to: • avoid significant adverse impacts on health and quality of life; • mitigate and minimise adverse impacts on health and quality of life; and • where possible, contribute to the improvement of health and quality of life. through the effective management and control of environmental, neighbour and neighbourhood noise. These aims are developed by reference to the concepts NOEL (No Observed Effect Level) and LOAEL (Lowest Observed Adverse Effect Level). NPSE also refers to SOAEL (Significant Observed Adverse Effect Level). It recognises that there is no universally applicable threshold for these concepts. Consequently, the SOAEL is likely to be different for different noise sources and receptors and at different times. Even so, significant effects should be avoided, taking account of sustainability aims. Where noise impact is between LOAEL and SOAEL, the NPSE requires that all reasonable steps should be taken to mitigate adverse effects while taking account sustainable development aims. It notes (para. 2.7) that the NPSE should consider noise alongside other relevant issues and noise should not to be considered in isolation. The Planning Practice Guide (PPG) refers to the NPPF and provides further guidance on the interpretation of no, lowest and significant observed adverse effect level described in the NPSE. The PPG provides a commentary on the noise exposure hierarchy, based on the ‘likely average response’.


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Perception Examples of Outcomes Increasing Effect Level Action

Not noticeable No Effect No Observed Effect

No specific measures required

Noticeable and not intrusive

Noise can be heard, but does not cause any change in behaviour or attitude. Can slightly affect the acoustic character of the area but not such that there is a perceived change in the quality of life.

No Observed Adverse Effect

No specific measures required

Lowest Observed Adverse Effect Level

Noticeable and intrusive

Noise can be heard and causes small changes in behaviour and/or attitude, e.g. turning up volume of television; speaking more loudly; where there is no alternative ventilation, having to close windows for some of the time because of the noise. Potential for some reported sleep disturbance. Affects the acoustic character of the area such that there is a perceived change in the quality of life.

Observed Adverse Effect

Mitigate and reduce to a minimum

Significant Observed Adverse Effect Level

Noticeable and disruptive

The noise causes a material change in behaviour and/or attitude, e.g. avoiding certain activities during periods of intrusion; where there is no alternative ventilation, having to keep windows closed most of the time because of the noise. Potential for sleep disturbance resulting in difficulty in getting to sleep, premature awakening and difficulty in getting back to sleep. Quality of life diminished due to change in acoustic character of the area.

Significant Observed Adverse Effect

Avoid

Noticeable and very disruptive

Extensive and regular changes in behaviour and/or an inability to mitigate effect of noise leading to psychological stress or physiological effects, e.g. regular sleep deprivation/awakening; loss of appetite, significant, medically definable harm, e.g. auditory and non-auditory

Unacceptable Adverse Effect

Prevent

The PPG recognises a broad range of factors which can influence the relationship between noise level and the impact on those affected. Accordingly, the examples in the above table may not be relevant to a specific development and which should be considered on its merits within the specific context under consideration.

3.2 BS 8233:2014 AND WHO BS 8233:2014 Guidance on sound insulation and noise reduction for buildings gives absolute noise limits for steady state noise without a specific character (such as that from road traffic) inside residential properties as follows:


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Table 1: Indoor ambient noise levels for dwellings BS 8233 also provides guidelines for noise levels in residential gardens. It says:

For traditional external areas that are used for amenity space, such as gardens and patios, it is desirable that the external noise level does not exceed 50 dB LAeq,T, with an upper guideline value of 55 dB LAeq,T which would be acceptable in noisier environments. However, it is also recognized that these guideline values are not achievable in all circumstances where development might be desirable. In higher noise areas, such as city centres or urban areas adjoining the strategic transport network, a compromise between elevated noise levels and other factors, such as the convenience of living in these locations or making efficient use of land resources to ensure development needs can be met, might be warranted. In such a situation, development should be designed to achieve the lowest practicable levels in these external amenity spaces, but should not be prohibited.

These guidelines are in keeping with “Guidelines for Community Noise” published by the World Health Organization, 1999.

Area Critical health effect Noise level

Outdoor living area Serious annoyance, daytime and evening LAeq,16hr 55 dB Moderate annoyance, daytime and evening LAeq,16hr 50 dB

Dwelling, indoors Speech intelligibility and moderate annoyance, daytime and evening LAeq,16hr 35 dB Sleep disturbance, night-time LAeq,8hr 30 dB

LAmax 45 dB

Table 2: WHO guideline values for community noise The values in Table 2 need further elaboration. There is a variability in individual response to environmental noise, with some people being more noise-sensitive than others. The levels given for outdoor living areas are the noise level below which few people will be moderately/seriously annoyed; they do not represent an onset of moderate/serious annoyance for the general population. In effect, the levels protect the more sensitive section of the population. Likewise, the LAmax value is not the highest single noisy event that occurs during the night, but rather the WHO guidelines note For a good sleep, it is believed that indoor sound pressure levels should not exceed approximately 45 dB LAmax more than 10 to 15 times per night. Also, the scope of the WHO document is wider than that of BS8233. Whereas BS8233 advises the guidelines are primarily intended for consideration of “anonymous noise” (which is not defined), WHO state that the guidelines relate to community noise, which is defined as all noise, including neighbourhood noise, and that …typical neighbourhood noise comes from a range of noise sources including from premises and installations related to the catering trade (restaurant, cafeterias, discotheques, etc.); from live or recorded music, etc.


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LAeq,T is the average noise level, measured over the time period T. BS8233 and WHO advise that the time period for the daytime should be a 16-hour average (07:00-23:00). The night period is defined as 23:00-07:00.

4. AMBIENT NOISE SURVEY In order to support the assessment of the effect of noise on the proposed development, existing ambient noise levels at the site have been measured. Details of the measurement and analysis of noise across the site is described in following sections.

4.1 SURVEY DATE, LOCATION AND EQUIPMENT Ambient noise measurements were carried out during a site survey between 14 and 17 November 2017. This survey consisted of unattended, fixed-position noise loggers at two locations on the subject site measuring noise in contiguous 5-minute periods. Noise logger 1 was located close to the eastern site boundary approximately 15m from the edge of the A605 carriageway. The microphone was raised to a height of 4.5m above ground level. The location was not screened from noise on A605 (except by the strip of vegetation along the roadside which provides an insignificant amount of attention at higher frequencies). Noise logger 2 was located on the south-western site boundary where the site borders the grounds of Prince William School. The microphone was raised to a height of 3m above ground level. At this location, the microphone was more distant from the A605 but again was partially screened from the A605 by the topography of the site and by vegetation around the boundary of the site. Both these measurement locations are shown on the site location plan in Appendix A. The following equipment was used during the survey: • Bruel & Kjaer Type 2250 Sound Level Meter s/n 2726905 • Bruel & Kjaer Type 4189 Microphone s/n 2710995 • Bruel & Kjaer Type 4231 Acoustic Calibrator s/n 2730220 • Bruel & Kjaer Type 2260 Sound Level Meter s/n 2311704 • Bruel & Kjaer Type 4189 Microphone s/n 2733049 • Bruel & Kjaer Type 4231 Acoustic Calibrator s/n 2688672 • Bruel & Kjaer Type ZC 0026 Preamplifier s/n Before and after the survey, the sound level meters were field-calibrated in accordance with the manufacturer’s guidelines, and no significant drift was observed. The meters, microphones and field calibrators are laboratory calibrated biennially in accordance with UKAS procedures or to traceable National Standards.

4.2 RESULTS The measurements from the fixed noise loggers have been summarised into contiguous 5-minute periods to present the noise profile throughout the monitoring period. Noise parameters consisted of equivalent continuous (LAeq) noise levels and statistical noise levels (termed Ln, where n is the percentage of time the level is exceeded during the measurement period).


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Overall band measurements were stored for later analysis. In addition, maximum (LAmax) noise levels were recorded in contiguous 5 minute periods. The results of the noise logger measurements are shown graphically in Appendix B. The charts in Appendix B show noise levels that gradually increase during the morning, peaking during early morning rush hour; remaining consistent during the daytime, peaking again during evening rush hour; gradually decreasing throughout the evening and then dropping during the night-time. This is entirely consistent with a noise environment dominated by road traffic noise. This aligns with observations on site. No audible activity from Hutchinson’s was observed at all during the two site visits carried out. Neither was any activity from Hutchinson’s identifiable from the measurements and recordings made throughout the 4 days of measurement. During site visits, it was observed that there were various activities generating noise at different premises within the adjacent commercial/industrial area, however none of this activity was audible on the development site. The measured noise data was validated using weather data taken from Weather Underground1 which provides historic measured weather data from thousands of personal and airport-based weather stations throughout the UK. Measurements of wind speed and direction at a number of locations within the local area were analysed and broadly consistent results were observed. These measurements were used to identifying prevailing wind direction and typical wind speeds on site to improve the accuracy of the prediction model. The results of the noise logger measurements were then summarised into relevant daytime (07:00-23:00 hours) and night-time (23:00-07:00 hours) periods, coinciding with the widely agreed definitions. Daytime and night-time noise levels are determined by taking the typical LA10,18hr measured in accordance with Calculation of Road Traffic Noise, Department of Transport and Welsh Office, 1988. These LA10,18hr values are then converted to LAeq,16hr and LAeq,8hr levels using the conversion procedure (Method 3) in 'Method for converting the UK road traffic noise index LA10,18h to the EU noise indices for road noise mapping (Defra 2006)'. The resultant levels are commensurate with the mean measured LAeq,day and LAeq,night across the measurement period. Typical LAFmax,night levels for each night were determined based on the 10-15th highest measured 5 minute LAFmax between 23:00 and 07:00 each night, in accordance with guidance in the WHO2. The highest of these typical LAFmax,night values was then used to represent the typical night-time LAFmax. Table 3 below summarises the measured daytime and night-time LAeq levels and design LAmax levels.

Noise metric Noise Logger 1 –

measured level (dB) Noise logger 2 –

measured level (dB)

Daytime LAeq 73 53 Night-time LAeq 64 45 Night-time LAmax 83 60

Table 3: Summary of results of noise monitoring

1 Weather Underground is a subsidiary of The Weather Company and IBM. Weather data collected using Weather Underground API https://www.wunderground.com/weather/api/. 2 The WHO “Guidelines for community noise” document states that, for a good nights’ sleep, the LAmax level should not exceed 45 dB more than 10 to 15 times.


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5. ASSESSMENT OF NOISE AT PROPOSED RESIDENCES 5.1 NOISE PREDICTION MODEL

In order to assess noise at site it is necessary to predict how noise propagates across the site.

5.1.1 Noise prediction methodology

Noise levels across the site are predicted using proprietary numerical noise modelling software (Predictor3). This software package meets the requirements of ISO 9613 Part 2:19964. The noise model takes account of the following in its calculations procedures: • Source sound power level (for point, line and area sources) • Reflection from nearby structures and source directivity • Distance from noise source (geometric spreading) • Atmospheric absorption • Acoustic screening of intervening structures and topography • Ground absorption • Ground effects (which includes the height of ground relative to the noise source) The accuracy of the predictions is maximised by validating predicted levels using the long-term measured at the two noise logger locations. Predicted levels were shown to be equal to measured levels (within measurement/modelling tolerances). This gives a high level of confidence in the accuracy of the predicted levels.

5.1.2 Results

The results of the noise prediction model show that noise levels across the site, particularly closer to the A605, are relatively high as a result of road traffic on the A605. The Institute of Acoustics (IoA) have issued a document ProPG: Planning & Noise - Professional Practice Guidance on Planning & Noise (May 2017) which includes guidance on carrying out an initial site risk assessment. At the location of the most noise-exposed properties on site, noise levels are around LAeq,T 65 dB during the daytime and LAeq,T 55 dB during the night-time. This would lead to the site being categorised as Medium Risk under the ProPG risk assessment procedure. Consequently, it is necessary to look at reducing noise levels in internal and external areas across the site by design to clearly demonstrate that a significant adverse impact will be avoided and to ensure any adverse impacts will be mitigated and minimised.

5.2 NOTES ON ACOUSTIC DESIGN The IoA document ProPG gives information on the principles of ‘good acoustic design’. It notes that acoustics should and cannot be considered in isolation of other factors, but highlights the need for the potential effects of noise to, at least in part, guide the design.

3 Bruel and Kjaer – Predictor (Predictor-LimA) v11.00 Environmental Noise Calculation Software Package, Type 7810 4 ISO 9613-2:1996 “Acoustics – Attenuation of sound during propagation outdoors – Part 2: General method of calculation to

determine Noise Levels


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At this stage, the project is in outline and all matters aside from access will be reserved. Accordingly, it is not possible to complete a full and thorough Acoustic Design Statement at this stage since most aspects of the design are not fixed. However, as noted by the EHO, it is prudent to report on how acoustic considerations have fed into the initial design so far and to set out how the principles of good acoustic design will feed in to the design going forward. ProPG highlights a number of key areas of design which should be considered in any assessment, so each of these are discussed with reference to the proposed development.

5.2.1 Reducing noise level at source

In general, mitigating noise at its source rather than at the sensitive receptor is an effective and favourable means of noise control. However, in many circumstances, changes at source are not feasible. This site is one such case, since the noise environment is dominated by noise from the A605, and relocating or reducing noise from this source is outside the scope of this development. Without relocating the road, or affecting the amount or speed of traffic on the road, installation of a noise barrier as close to the road as possible is the next best option for reducing noise levels across the whole site, and this is addressed below.

5.2.2 Noise barriers

As noted above in Section 5.2.1, a noise barrier can be an effective mitigation measure where it is located close to the source. Barriers close to a source can very effectively reduce noise levels across the entire site. Furthermore, a well-situated barrier will reduce noise levels in external areas as well as reducing noise exposure to the facades of residential properties, reducing the need for upgraded façade performance and minimising adverse impacts when residents choose to open windows. At this site, the planning boundary at the eastern side runs close to the A605. The proposals will retain the existing planting region as it is beneficial for various reasons (including providing a natural set-back zone and to minimise visual impacts on the surrounding environment). The possibility of siting a noise barrier to the east of this planting region has been considered, however it is a design principle of the development to minimise character and landscape impacts to the wider area. Furthermore, indicative noise modelling shows that the current proposals (to site a noise barrier immediately inside the planting region) will limit noise propagation across the site almost as effectively as a barrier located to the east of the planting region. Current proposals incorporate a 3m acoustic barrier. Since the original issue of this report, and the incorporation of indicative layouts into the proposals the proposed barrier has been extended slightly as show in Appendix C of this report. The detailed requirements for the acoustic barrier are outlined in Section 6.1 and Appendix C. Contour plots showing the predicted noise propagation across the site both in the daytime and night-time (with the acoustic fence in place) are included in Appendix D.


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5.2.3 Site layout

When developing the design of a site such as this, which incorporates multiple dwellings, there are a number of ways in which the layout can be optimised to improve acoustic amenity. ProPG discusses a number of these, which are addressed here: Maximising separation The site layout is favourable in that there is a natural set-back zone provided by the vegetation running down the eastern site boundary, which will be retained as part of the proposals. In addition, the current layouts propose setting the properties back even further, with a minimum separation distance from the edge of the road of around 30m. A sizeable attenuation pond is included in the proposals. At the pre-application discussions, this was proposed to be situated towards the centre of the site. Following the advice received and taking into account comments from the EHO, this has been moved, as shown in Figures 1 and 2 below.

Figure 1: Original indicative layout

Figure 2: Updated indicative layout

The new proposals provide some additional separation from the surrounding rounds for a number of the properties. The potential to locate the attenuation pond along the east boundary has also been considered, however due to the topography of the site, it is understood that this is not possible. Barrier blocks or non-sensitive elements as screens ProPG states that:

“On larger developments, a “barrier block” can be used to protect the residential development from noisy roads or railways… A continuous frontage is one way to lower noise levels in the rest of the property.” “The block should run along the edge of the site closest to and parallel to the noise source and wrap around the sides of the property to protect the sides”. “The block should preferably be used for non noise-sensitive purposes such as parking cars or refuse storage.”


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In order for a barrier block to be effective, it must provide functional screening to the remainder of the site. This means that a barrier block at this site would have to be broadly continuous along the eastern boundary, over a distance of around 250m (or longer if it was to wrap around the sides).

It is not considered that there is any scope at this site to include such a block. Primarily, this due to the proposal intending to remain respectful to the density and character of the surrounding area. To do this, the development is proposed to consist primarily of individual houses, each with a separate garden, parking provision and refuse storage. Given this guiding principle, there would be no requirement for a non-sensitive block since parking will take the form of external spaces outside properties and individual garages and refuse storage would be localised to the houses. Similarly, whilst in theory a continuous row of terraces along might provide an effective barrier; this would involve a high density of properties on the eastern boundary, which would be very inconsistent with the surrounding environment. It would also likely be counter-productive in terms of creating favourable acoustic amenity since it would likely mean that at least half of the habitable rooms in each terraced property would have to face the noise source directly and would require high performance glazing and mechanical ventilation. Instead, the current indicative proposals show individual properties, arranged with consideration to the existing topography and internal layouts to provide a balance between screening and density. Site topography ProPG points out the good acoustic design can involve either taking advantage of existing topography or by changing the site levels. In this case, there are no proposals to adjust the site levels in a significant way (other than in a localised fashion to incorporate roads within the site. However, at this site retaining the existing topography will have a neutral effect in terms of the potential for noise impact. Firstly, this is due to the fact that the gradient from West to East across the site is minimal. Secondly, some initial indicative noise modelling has been carried out to assess what theoretical effect would be achievable through levelling of the site. This showed that on a flatter site (assuming the proposed barrier is in place) while noise levels would be reduced slightly (~1 dB) for properties nearer to the road, they would increase slightly for at more distant properties. This is because an effect of the existing topography is to provide some additional natural screening for properties set back further from the road. Therefore, overall there is no significant advantage or disadvantage to adjusting the topography of this site. Building layout/orientation Another means of minimising the impact of noise on amenity is to put windows or doors of habitable rooms on less noise-exposed facades away from the key noise source. This principle minimises intrusive noise into habitable rooms in properties close to the noise sources, whilst allowing these properties to provide screening for more distant sources across the site. Accordingly, the current indicative layout shows all properties closest to the eastern boundary oriented such that their blank, side facades face towards the A605. In these proposed houses, the facades with windows and doors to habitable rooms are then either partially or wholly screened from the A605.


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5.2.4 Intrusive noise and façade sound insulation

In accordance with BS8233 and WHO, a significant factor in determining whether a development is acceptable is the predicted level of internal noise in the proposed dwellings. Based on the measured and predicted external noise levels, indicative calculations of intrusive noise into typical dwellings have been carried out. These calculations show expected internal noise levels in typical living rooms and bedrooms. These calculations make assumptions about the size and construction of the building façade elements, as well as acoustic properties of the receiving room, such as the volume and reverberation time based on common dwellings. It is then possible to provide an indication of the level of mitigation (in terms of glazing and ventilation to habitable rooms) that will be required at this site to ensure that acceptable internal ambient levels are achieved. Sound insulation data for façade elements has been taken from sources such as standard data provided by BRE and DETR, Spectrum’s library of measurement data, calculations using Marshall Day’s Insul software as well as manufacturer’s data and the BRE/CIRIA publication ‘Sound Control for Homes’. Information regarding typical internal finishes for the type of rooms considered is based on acoustic properties Spectrum have measured in a range of occupied dwellings. In the most noise-exposed areas of the site, for internal ambient noise levels inside habitable rooms to meet the BS8233 and WHO criteria with open windows, the external noise level has to exceed the internal noise limit by no more than 10-15 dB. This is equivalent to an upper guideline level of LAeq,T 50 dB during the daytime and LAeq,T 45 dB during the night-time. As Table 3 shows, with no mitigation in place external noise levels exceed these levels across the majority of the site. Therefore, an initial acoustic design process has taken place and a number of measures have been recommended. The most significant of these is that a barrier should be incorporated into the initial proposals (detailed below in Section 6.1 and Appendix C). Additionally, initial site layouts have been optimised for acoustic amenity (taking into account the limitations of the site and non-acoustic requirements). Given these initial indicative designs for the barrier and site layouts, calculations of intrusive noise into key habitable rooms in the most noise exposed properties are included in Appendix D. These calculations show that internal ambient noise levels are predicted to be below internal ambient noise level limits (taken from the BS8233 and WHO criteria) in the most noise-exposed properties, assuming the mitigation measures including glazing and ventilation performance requirements, recommended below in Section 6 are incorporated. This is a good indication that any potential for adverse effect can be effectively mitigated and reduced.

5.2.5 Noise in outdoor amenity areas

The proposed scheme will provide external amenity space for each property. As noise levels are predicted to be relatively high across the site, a noise barrier on (or close to) the eastern site boundary has been recommended as a mitigation measure and incorporated into the noise prediction model.


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As shown on the contour plots in Appendix D, external noise levels across the site with the proposed noise barrier in place are predicted to range from around LAeq 47 dB to around LAeq 61 dB. This means that external noise levels in external amenity areas for most properties will be either below the lower WHO guideline level (which is also cited by BS8233 as a desirable level) or between the lower and upper WHO guideline levels (cited by BS8233 as acceptable). Indeed, based on the indicative layouts, 69 of the 100 properties have gardens in which noise levels are predicted to be below the lower WHO guideline of LAeq 50 dB. A further 9 are predicted to be between the lower and upper guideline levels (LAeq,T 50 and 55 dB). Only 14 houses will have gardens above the upper guideline level. In addition to the houses, the current proposals include 8 flats in two small blocks, which it is understood will not have private amenity space.

However, for gardens at 14 most noise-exposed properties, namely those closest to the eastern site boundary, noise levels in gardens are predicted to be up to LAeq 61 dB. Although this exceeds the upper WHO threshold and BS8233 upper guideline, BS8233 advises that it is also recognized that these guideline values are not achievable in all circumstances where development might be desirable. In higher noise areas, such as city centres or urban areas adjoining the strategic transport network. It goes on to recommend that in such circumstances: development should be designed to achieve the lowest practicable levels in these external amenity spaces, but should not be prohibited. In this case, as discussed, a large acoustic barrier is recommended in order to mitigate noise level as far as practicable. In context of the whole site the import factors are that while a small percentage of garden areas may be exposed noise levels in excess of the guidelines, these have been reduced as far as possible. Furthermore, across the majority of the site, noise levels in gardens will meet the guidelines and in areas which benefit from significant screening and are more distant from the A605, noise levels will meet the lower, desirable guideline criteria. In addition, with the recommended noise barrier in place it will be straightforward to achieve acceptable internal ambient noise levels in all properties across the site. In summary then, guideline levels will be met across the majority of the site and although there may be exceedances in some areas, measures have been incorporated to mitigate and minimise adverse noise effects in external amenity areas as far as reasonably practicable.

6. PROPOSED MITIGATION MEASURES 6.1 ACOUSTIC FENCE

In order to ensure that noise levels are reduced as far as possible in external amenity areas and to minimise noise exposure at the facades of dwellings, Spectrum recommend that acoustic fencing is installed along the inside of the planting region close to the eastern site boundary. This acoustic fence should have the following properties: • 3m (or greater) in height • No holes or penetrations • A surface density of at least 10 kg/m2 These requirements can readily bet met with common approaches to fencing, for example a close-boarded timber fence. The fencing should be installed in the location, and to the extents, shown on the marked up drawing included in Appendix C. In lieu of a fence, it will also be possible to incorporate a bund of equivalent height, or a combination of both these elements to the same total height.


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6.2 FAÇADE ACOUSTIC SPECIFICATION As the calculations in Appendix E demonstrate, double glazing with a minimum performance of Rw(Ctr) 35(-3) dB coupled with standard hit-and-miss trickle vents with a minimum performance of Dn,e,w(Ctr) 32(0) dB will provide sufficient sound insulation to ensure the guideline levels for internal ambient noise in habitable rooms (in line with BS8233 and WHO) are achieved in almost all properties across the development. Furthermore, in a significant number of properties, external levels will be low enough that these can be reduced or even allowing for opening windows for ventilation. The only exception to this is in properties very close to the A605, where it will be necessary to use acoustically rated trickle vents in bedrooms only to ensure acceptable internal ambient noise levels are achieved. These acoustic trickle vents must achieve and acoustic performance of at least Dn,e,w(Ctr) 44(-2) dB. Glazing and trickle ventilation systems must be selected to meet these performance requirements. It is also important to note that the standard for glazing applies to the whole window or, if applicable, sliding or hinging door, including frames and seals. Typically, to meet an acoustic performance standard of Rw(Ctr) 35(-3) dB, glazing with a build-up of 10/12/6 will suffice. Similarly, there are a number of common window-frame mounted trickle vent products which will achieve Dn,e,w(Ctr) 32(0) dB and acoustic trickle vents which achieve Dn,e,w(Ctr) 44(-2) dB. These performance standards can be issued to suppliers who will be able to provide systems which meet the requirements. The acoustic requirements for each window or glazed door are specified in terms of both the Rw and the Rw+Ctr performance standards. Rw is the standard weighted sound reduction of a façade element. Rw+Ctr (which is sometimes written as Rtra) is the weighted sound reduction of a façade element with respect to road traffic noise. Both performance requirements listed here are required to be met or exceeded by the selected glazing system. Similarly with the ventilation requirement the value in parentheses is the Dn,e,w+Ctr performance standard. The selected ventilation system must meet both performance values.

7. CONCLUSION Persimmon Homes have commissioned Spectrum Acoustic Consultants to complete a noise impact assessment to accompany an application for outline planning permission for a proposed residential development at land between St Christopher’s Drive and A605 Oundle Bypass, Oundle. Following the development of an indicative layout and comments from the Local Authority EHO at pre-application stage, the report has been updated to include predictions with the indicative layouts and discussion of how the design so far has considered acoustic amenity in line with the principles outlined in ProPG. Road traffic is the dominant noise source at the proposed development site. Given this environment, the way in which acoustic conditions are affected by the site layout, building layout and site topography are discussed. Possible different approaches to mitigation are also considered, including mitigation at source and barrier blocks. Using measured noise levels on site noise levels as a basis, noise levels across the site have been predicted using computer noise modelling software. Internal ambient noise levels inside the most noise-exposed dwellings have been calculated based on the predicted external noise levels.


MM588/17180/Rev. 1 14

The assessment demonstrates that it will be possible for internal ambient noise levels to meet the guideline levels in BS8233 and WHO Guidelines for Community Noise through a series of noise mitigation measures in the form of uprated glazing systems and passive vents as well as an extensive noise barrier. Overall, this report demonstrates that, with appropriate noise mitigation measures in place, a significant adverse noise impact on the proposed development is unlikely and any adverse impacts will be able to be mitigated and minimised.


A P P E N D I X A

Site location plan showing measurement positions

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Site location plan showing measurement positions

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Position 2

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A P P E N D I X B

Chart showing measured noise levels

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Noise levels at location 1: Logger on eastern site boundary, near A605 (14 to 17 November 2017)

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Noise levels at location 2: Logger on southern site boundary, bordering Prince William School grounds (14 to 17 November 2017)

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Site location plan showing recommended noise barrier location

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Site block plan showing recommended noise barrier location

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Location of noise barrier


A P P E N D I X D

Contour plots showing noise across the site


A P P E N D I X E

Calculations of intrusive noise

Calculated Indoor Ambient Noise Levels (as per BS 8233:2014 Annex G)Project:Project number:Date:

Plot:Room:

Daytime (L Aeq,16hr )Unit Value Description Term 63 125 250 500 1k 2k 4k 8k

EXTERNAL NOISE LEVELExternal noise level L eq,1 59 56 57 61 58 44 28 14 L Aeq,1 61 dBFaçade correction factor C 0 0 0 0 0 0 0 0

INCIDENT FAÇADE NOISE LEVELIncident noise level Façade 1 L eq,ff 59 56 57 61 58 44 28 14 L Aeq,ff 61 dB

ROOM DATARoom description and reverberation time Volume 80 Living Room RT60 0.6 0.6 0.5 0.5 0.4 0.4 0.4 0.3 s

FAÇADE ELEMENTS (Façade 1)Glazing Area 2 Pilkington 10/6-16/6 Rw 23 24 24 32 37 37 44 47 Rw / Rw+Ctr 35 / 32 dBWall Area 20.6 Brick and block external wall Rw 34 40 44 45 51 56 60 63 Rw / Rw+Ctr 50 / 47 dBVent No. off. 2 Greenwood 4000 SBW (Hit and miss) Dn,e 38 38 37 34 30 34 37 46 Dn,e,w / Dn,e,w+Ctr 33 / 32 dBNone --

RESULTSTotal calculated indoor noise level L eq,2 32 27 27 29 29 11 - - L Aeq,2 31 dB

Octave band centre frequency

Façade 1

Ashton Road, Oundle1718007/06/2019

Typical property (P81 NSS) close to the eastern site boundaryLiving Room

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Plot:Room:

Daytime (L Aeq,16hr )Unit Value Description Term 63 125 250 500 1k 2k 4k 8k



ROOM DATARoom description and reverberation time Volume 21 Bedroom RT60 0.4 0.5 0.4 0.4 0.3 0.3 0.3 0.2 s

FAÇADE ELEMENTS (Façade 1)Glazing Area 1.3 Pilkington 10/6-16/6 Rw 23 24 24 32 37 37 44 47 Rw / Rw+Ctr 35 / 32 dBWall Area 15.5 Brick and block external wall Rw 34 40 44 45 51 56 60 63 Rw / Rw+Ctr 50 / 47 dBVent No. off. 1 Greenwood EHA574 (Acoustic trickle) Dn,e 34 34 40 39 42 49 43 43 Dn,e,w / Dn,e,w+Ctr 44 / 42 dBNone --

RESULTSTotal calculated indoor noise level L eq,2 38 34 35 35 31 17 6 - L Aeq,2 35 dB

Bedroom


Typical property (P81 NSS) close to the eastern site boundary

Octave band centre frequencyBroadband term

Façade 1


Plot:Room:

Night time (L Aeq,8hr )Unit Value Description Term 63 125 250 500 1k 2k 4k 8k





RESULTSTotal calculated indoor noise level L eq,2 30 26 26 27 22 8 - - L Aeq,2 27 dB

Bedroom




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Plot:Room:

Night time (L AMax)Unit Value Description Term 63 125 250 500 1k 2k 4k 8k

EXTERNAL NOISE LEVELExternal noise level L Max,1 75 70 74 77 78 67 54 48 L AMax,1 80 dBFaçade correction factor C 0 0 0 0 0 0 0 0

INCIDENT FAÇADE NOISE LEVELIncident noise level Façade 1 L Max,ff 75 70 74 77 78 67 54 48 L AMax,ff 80 dB



RESULTSTotal calculated indoor noise level L Max,2 51 45 46 45 40 25 14 6 L AMax,2 45 dB

Bedroom




Façade 1

Head Office Spectrum Acoustic Consultants Ltd 27-29 High Street Biggleswade Bedfordshire SG18 0JE UNITED KINGDOM

[email protected]

www.spectrumacoustic.com

appendix 19 - east-northamptonshire.gov.uk · appendix 1 page 1 appendix 19 outline noise impact...

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