WYETH LABORATORIES SITE HUNTERCOMBE LANE SOUTH TAPLOW ENVIRONMENTAL NOISE SURVEY & ASSESSMENT REPORT 4390/ENS 25 March 2011 Revision Number: 0 Issued For: ESA Planning 75 Wells Street London W1T 3QH Prepared by: Approved by: Robert Barlow Torben Andersen RBA Acoustics 104 The Foundry Annexe 65 Glasshill Street London SE1 0QR Tel: 020 7953 7233 Facsimile: 020 7953 7236 Email: info@rba-acoustics.co.uk
WYETH LABORATORIES SITE HUNTERCOMBE LANE SOUTH TAPLOW ENVIRONMENTAL NOISE SURVEY & ASSESSMENT REPORT 4390/ENS Contents 1.0 Introduction...1 2.0 Survey Methodology...1 3.0 Assessment Criteria...2 4.0 Calculation of Assessment Levels...4 5.0 Results...4 7.0 PPG 24 Assessment...6 8.0 Noise Modelling...7 9.0 Conclusion...7
1.0 Introduction Redevelopment of the land currently occupied by Wyeth Laboratories in Taplow is under consideration. The redevelopment is to comprise new residential properties in addition to new office space. As the site is affected by road traffic noise from Huntercombe Lane South and Huntercombe Spur road, ESA Planning has requested noise surveying is undertaken at the site. RBA Acoustics has been commissioned to undertake a survey of the existing noise levels and to prepare an assessment in line with PPG24 outlining the impact of noise levels across the proposed residential aspect of the development site. 2.0 Survey Methodology The residential aspect of the proposed development involves the construction of residential properties on land currently occupied by car parking and green-belt, adjacent to the Huntercombe Spur road. Noise levels at the site are affected by road traffic along the spur road and to a lesser extent Huntercombe Lane South. Noise levels from the M4, which is less than 1km to the south of the site, also provide a constant contribution to background noise levels. The site s proximity to London Heathrow Airport means that there are also regular aircraft fly-overs. A noise survey was therefore undertaken as follows: 2.1 Instrumentation The following instrumentation was used for the survey: Table 4390/T1 - Instrumentation Manufacturer Model Type Serial No. 01dB A&V Type 1 Sound Level Meter Blue Solo 01 60611 01dB A&V Pre Amplifier PRE 21 S 13678 Gras ½ Microphone MCE 212 84967 Certificate No. Calibration Expiry Date U7411 23 August 2011 01dB-Stell Calibrator Cal 21 50441920 U7409 23 August 2011 Larson Davis Type 1 Sound Level Meter SLM824 3853 Larson Davis Pre Amplifier PRM902 4252 U7347 10 August 2011 PCB - Microphone 377B02 109166 The sound level meters were calibrated both prior to and on completion of the survey with no calibration drift observed. 2.2 Noise Survey Noise monitoring was undertaken at two locations to determine corresponding noise levels during the daytime on 24 February and over the night-time period of 24 to 25 February 2011. Page 1
Continuous unattended 24 hour noise monitoring was undertaken at one position at the site. In addition, an attended short-form daytime survey was undertaken at a secondary position over a continuous three hour period between 11:00 and 14:00. The results of these measurements can be used to undertake an assessment of daytime noise levels as described in Section 4.0. Continuous noise monitoring was also undertaken at this secondary position during the entire night-time period from 23:00 to 07:00. Weather conditions over the monitoring periods were generally fine and acceptable for the noise measurement exercise. 2.3 Measurement Positions The measurement positions were selected so as to be indicative of noise levels incident on the proposed residential development. Noise levels were therefore recorded at two positions to be representative of traffic noise from the Huntercombe Spur and Huntercombe Lane South. Position 1: Position 2: This position was selected to be representative of noise from the Huntercombe Spur road. A microphone was attached to a tripod at a height of 1.2m and positioned approximately 40m from the roadside. In order to account for noise from traffic along Huntercombe Lane South, an additional measurement position was chosen close to the existing site road on the edge of the greenbelt. The microphone was positioned at a height of 1.2m above ground and approximately 100m from the road. These measurement positions are detailed on the attached Site Plan 4390/SP1. 3.0 Assessment Criteria 3.1 Planning Policy Guidance 24 Planning and Noise The Department of the Environment s Planning Policy Guidance note PPG24: Planning and Noise, dated September 1994, sets out the Government s planning policies with respect to noise. Local Authorities must take the guidance notes into account. When assessing a proposal for residential development near a source of noise both daytime and night-time L Aeq noise levels should be used to determine into which of the four Noise Exposure Categories (NECs) the site falls. Consideration should then be given to the advice given for each NEC as shown below. Page 2
Table 4390/T2 Description of NEC s NEC A B C D Description Noise need not be considered as a determining factor in granting planning permission, although the noise level at the high end of the category should not be regarded as a desirable level. Noise should be taken into account when determining planning applications and, where appropriate, conditions imposed to ensure an adequate level of protection against noise. Planning permission should not normally be granted. Where it is considered that permission should be given, for example because there are no alternative quieter sites available, conditions should be imposed to ensure a commensurate level of protection against noise. Planning permission should normally be refused. It should be noted that PPG24 also states that Categories B and C deal with situations where noise mitigation measures may make development acceptable. The following table indicates the (L Aeq ) noise levels defined within PPG24 for each Noise Exposure Category. Table 4390/T3 NEC Values Noise Source Road Traffic 07:00 23:00 23:00 07:00 Rail Traffic 07:00 23:00 23:00 07:00 Air Traffic 07:00 23:00 23:00 07:00 Mixed Sources 07:00 23:00 23:00 07:00 Noise Exposure Category A B C D <55 <45 <55 <45 <57 <48 <55 <45 55 63 45 57 55 66 45 59 57 66 48 57 55 63 45 57 63 72 57 66 66 74 59 66 66 72 57 66 63 72 57 66 >72 >66 >74 >66 >72 >66 >72 >66 3.2 BS 8233 BS 8233:1999 Sound insulation and noise reduction for buildings Code of Practice, draws on the results of research and experience to provide information on achieving internal acoustic environments appropriate to their functions. As part of this document recommendations are given to the internal noise levels which are commensurate with achieving good/reasonable resting and sleeping conditions within residential properties. As with PPG24 the values given are generally in terms of an L Aeq level although guidance is also given on the maximum noise level considered reasonable within bedrooms at night. The values given are detailed below:- Table 4390/T4 BS8233 Criteria Location Good Reasonable Living Rooms 30 40 Bedrooms 30 35 Page 3
In addition to the above, individual noise events within bedrooms at night should not normally exceed 45dBA L max. Although the document does not specifically outline the time periods over which these criteria should be considered suitable, it does note the time period should be appropriate for the activity involved. It is therefore common for the following assessment time periods to be adopted: Living Rooms - 07:00 23:00 Bedrooms - 23:00 07:00 4.0 Calculation of Assessment Levels The Calculation of Road Traffic Noise describes the following method by which a shortened survey can be used to obtain an equivalent daytime L Aeq. Measurements of L 10 are made over any three consecutive hours between 10:00 hours and 17:00 hours. Using L 10 (3 hour) as the arithmetic mean of the three consecutive values of hourly L 10, the current value of L 10 (18 hour) can be calculated from the relation: L 10 (18 hour) = L 10 (3 hour) 1 dba PPG24 also describes the relationship between L 10 (18 hour) and L Aeq (16 hour) for road traffic noise as shown below: L Aeq (16 hour) = L A10 (18 hour) 2dB 5.0 Results 5.1 Position 1 The measured noise levels are shown as time-histories on the attached Graphs 4390/G1-2 with averaged L Aeq noise levels summarised in the following Table 4390/T5 below. Table 4390/T5 - L Aeq Noise Levels Position L Aeq, period Noise Levels (db) Daytime (07:00 23:00) Night-time (23:00 07:00) 1 61.7 56.3 Spectral noise levels are graphically represented on Graphs 4390/G3. Page 4
5.2 Position 2 The relevant attended daytime measurements at Measurement Position 2 are detailed below Table 4390/T6 Position 2 Daytime Noise Levels Time Period Sound Pressure Level (db) L Aeq L A10 11:00-12:00 58.3 59.1 12:00-13:00 54.9 56.7 13:00-14:00 60.8 61.8 The relevant attended night-time measurements at Measurement Position 2 are detailed below: Table 4390/T7 Position 2 Night-time Noise Levels Time Period Sound Pressure Level (db) L Aeq L A90 L Amax 23:00-00:00 54.0 49.0 65.1 00:00-01:00 53.6 48.1 64.3 01:00-02:00 49.1 44.1 57.9 02:00-03:00 47.4 41.9 59.2 03:00-04:00 49.1 44.2 62.1 04:00-05:00 51.4 45.9 61.8 05:00-06:00 - - - 06:00-07:00 58.2 56.3 69.0 With reference to Section 4.0 the following daytime and night-time period L Aeq levels are as follows: Table 4390/T8 - L Aeq Noise Levels Position L Aeq, period Noise Levels (db) Daytime (07:00 23:00) Night-time (23:00 07:00) 2 56.2 53.3 Spectral noise levels are graphically represented on Graphs 4390/G4. Page 5
7.0 PPG 24 Assessment 7.1 Daytime Period The daytime noise levels calculated at the proposed façade lines of the site fall within NEC B (55-63 dba) for road traffic as defined in PPG 24. 7.2 Night-time Period The night-time noise levels calculated at the proposed façade lines of the site are also within NEC B (45-57 dba) as defined in PPG 24. In addition there were no exceedances of the 82dB L Amax, slow criterion at either measurement position. 7.3 General The PPG24 assessment for the daytime and night-time periods indicates the site falls into NEC B. Reference to PPG 24 indicates: Noise should be taken into account when determining planning applications and, where appropriate, conditions imposed to ensure an adequate level of protection against noise. Such conditions are likely to include the provision of acoustically rated glazing and trickle ventilation systems, such that the criteria detailed within BS 8233 can be achieved. The assessment has been undertaken on the worst-affected façades. Facades not directly overlooking the nearby roads are likely to be less affected by road traffic noise due to the acoustic screening which will be provided by the development itself. Page 6
8.0 Noise Modelling To be completed following receipt of residential scheme plans. 9.0 Conclusion Environmental noise surveying has been undertaken at the Wyeth Laboratories site in Taplow. The results of our measurements have been analysed in terms of the Noise Exposure Catagories as defined in PPG24. Noise contours have also been provided across the site using the CadnaA software. The results of our measurements indicate that the site falls within NEC B. PPG24 states that: Categories B and C deal with situations where noise mitigation measures may make development acceptable. Measures likely to be required include the provision of acoustically upgraded glazing and ventilation systems. Page 7
Appendix A - Acoustic Terminology db : Decibel - Used as a measurement of sound pressure level. It is the logarithmic ratio of the noise being assessed to a standard reference level. db(a) : The human ear is more susceptible to mid-frequency noise than the high and low frequencies. To take account of this when measuring noise, the 'A' weighting scale is used so that the measured noise corresponds roughly to the overall level of noise that is discerned by the average human. It is also possible to calculate the 'A' weighted noise level by applying certain corrections to an un-weighted spectrum. The measured or calculated 'A' weighted noise level is known as the db(a) level. Because of being a logarithmic scale noise levels in db(a) do not have a linear relationship to each other. For similar noises, a change in noise level of 10dB(A) represents a doubling or halving of subjective loudness. A change of 3dB(A) is just perceptible. L An (e.g L A10, L A90 ) If a non-steady noise is to be described it is necessary to know both its level and the degree of fluctuation. The L n indices are used for this purpose, and the term refers to the level exceeded for n% of the time, hence L 10 is the level exceeded for 10% of the time and as such can be regarded as the 'average maximum level'. Similarly, L 90 is the average minimum level and is often used to describe the background noise. L eq : L eq is defined as a notional steady sound level which, over a stated period of time, would contain the same amount of acoustical energy as the actual, fluctuating sound measured over that period (1 hour). L Aeq L max,t The level of notional steady sound which, over a stated period of time, would have the same A-weighted acoustic energy as the A- weighted fluctuating noise measured over that period. The instantaneous maximum sound pressure level which occurred during the measurement period, T. It is commonly used to measure the effect of very short duration bursts of noise, such as for example sudden bangs, shouts, car horns, emergency sirens etc. which audibly stand out from the general level of, say, traffic noise, but because of their very short duration, maybe only a very small fraction of a second, may not have any effect on the L eq value. Page 8
Position 1 Position 2 Wyeth Laboratories Site, Huntercombe Lane South, Taplow Site plan detailing Measurement Positions Site Plan 4309/SP1 25 March 2011 Not to Scale 104 The Foundry Annexe, 65 Glasshill St, London SE1 0QR Telephone: 020 7953 7233 Facsimile: 020 7953 7236
Wyeth Laboratories, Taplow L Aeq Time History Thursday 24 February to Friday 25 February 2011 100 90 Sound Pressure Level (db re 2x10-5 Pa) 80 70 60 50 40 30 20 10 0 11:15 12:45 14:15 15:45 17:15 18:45 20:15 21:45 23:15 00:45 02:15 03:45 05:15 06:45 08:15 09:45 Time (hh:mm) LAeq Graph 4390/G1
Wyeth Laboratories, Taplow L A90 & L Amax Time History Thursday 24 February to Friday 25 February 2011 110 100 Sound Pressure Level (db re 2x10-5 Pa) 90 80 70 60 50 40 30 20 10 0 11:15 12:45 14:15 15:45 17:15 18:45 20:15 21:45 23:15 00:45 02:15 03:45 05:15 06:45 08:15 09:45 Time (hh:mm) LAmax LA90 Graph 4390/G2
Wyeth Laboratories, Taplow Daytime and Night-time L eq values Position 1 80 70 Sound Pressure Level (db re 2x10-5 Pa) 60 50 40 30 20 10 0 63 125 250 500 1k 2k 4k 8k Frequency (Hz) Daytime (07:00-23:00) Night-time (23:00-07:00) Graph 4390/G3
Wyeth Laboratories, Taplow Daytime and Night-time L eq values Position 2 80 70 Sound Pressure Level (db re 2x10-5 Pa) 60 50. 40 30 20 10 0 63 125 250 500 1k 2k 4k 8k Frequency (Hz) Daytime (07:00-23:00) Night-time (23:00-07:00) Graph 4390/G4