Morgan Sindall NW PSBP Dee Point Primary School Environmental Noise Report Job No: 1010273 Doc No: 1010273-RPT-00001 Latest Revision: - Date: 1/10/2014 Cundall Johnston and Partners LLP 4th Floor Cathedral Court 15 Colmore Row Birmingham B3 2BH Tel +44 (0)121 262 2720 www.cundall.com
Project name Dee Point Primary School Job Number Report Name Environmental Noise Report 1010273 Document Revision History Revision Ref Issue Date Purpose of issue / description of revision Document Validation (latest issue) Revision - Issue Date 1/10/2014 Purpose of issue / description of revision / version Planning Report Prepared by Checked by Verified by Initials TN AJP AJP Signature Dee Point Primary School Environmental Noise Report Page 2 of 14
Contents Introduction... 4 Assessment criteria... 5 2.1 Acoustic Performance Standards for PSBP... 5 2.2 BS 4142: 1997... 5 Noise survey details... 6 3.1 Jacobs noise assessment... 6 3.2 Cundall noise assessment... 7 Noise impact on the school... 10 4.1 Glazing... 10 4.2 Ventilation... 10 4.3 External walls / Roof construction... 11 Limiting noise levels for services plant... 12 5.1 Nearest noise sensitive receptors... 12 5.2 Limiting noise levels... 12 Cundall measurement data... 14 6.1 Daytime Survey 11 th September 2014... 14 6.2 Night time Survey 18 th September 2014... 14 This report is the copyright of Cundall Johnston & Partners LLP. It has been prepared for the sole and confidential use of Morgan Sindall and cannot be reproduced in whole or in part or relied upon or used by any third party without the express written authorisation of Cundall Johnston & Partners LLP. If any third party whatsoever comes into possession of this report, they rely on it at their own risk and Cundall accepts no duty or responsibility (including in negligence) to any such third party. Dee Point Primary School Environmental Noise Report Page 3 of 14
Introduction Cundall has been commissioned by Morgan Sindall to carry out an acoustic assessment in relation to the proposed Dee Point Primary School in Chester, part of the North West PSBP batch. Proposals are to build a new, two storey primary school to replace the existing school which will be demolished as part of the works. The new school will be located within the same site boundary as the existing school, only it will be located on the playing fields, to the south of the existing school. The location of the site is off Blacon Point Road in Chester at the following address: Blacon Point Road, Blacon, Chester, CH1 5NF This site is generally bounded by residential areas, to the west, north and east. Blacon Point Road forms the northern site boundary. To the south is the A548, however the view is partially obscured by car sales garages. Noise surveys have been carried out on the site to determine the existing noise impact on the site and the background noise levels at night. The purpose of this report is to: document measured noise levels around the site; assess the predicted noise impact on the school and comment on glazing and ventilation; set limiting noise levels for services plant. Dee Point Primary School Environmental Noise Report Page 4 of 14
Assessment criteria The acoustic assessment in this report is based on the following documents: Acoustic Performance Standards for the Priority Schools Building Programme, v1.7; BS 4142: 1997 Method for Rating industrial noise affecting mixed residential and industrial areas. 2.1 Acoustic Performance Standards for PSBP Table 1 of the Acoustic Performance Standards for the PSBP sets out internal noise level criteria for each type of school space. Typically, Internal Ambient Noise Levels [IANL] for general classbases have a noise level criteria of 35 db LAeq,30mins, with practical classbases a higher IANL of 40 db LAeq,30mins. Where rooms are mechanically ventilated, the combined noise break-in and mechanical services noise must achieve the IANL criteria set out in Table 1. A natural ventilation system or mixed mode/hybrid system should not exceed the IANLs defined in Table 1 of the standard by more than 5 db. For example, the IANL criteria for a naturally ventilated standard classbase would be 40 dba, as opposed to 35 dba LAeq,30mins. Noise from mechanical parts of a mixed mode system, such as the NVHR units should meet the limits identified in Table 1 [i.e. no additional 5 db] of the PSBP. It is acceptable, and recommended that during unusually hot weather, a means is provided for the teacher to increase the air velocity in the room to improve comfort [Ref. Acoustic Performance Standards for PSBP, Section 2.1.4]. 2.2 BS 4142: 1997 This Report sets limiting noise levels for any new items of services plant. Best practice, based on the methodology set out in BS 4142, is for any new items of plant to be designed such that the rating 1 level on the nearest noise sensitive premises [typically adjacent residential dwellings] does not exceed 10 db below the existing background noise levels. In accordance with BS 4142, this approach gives a positive indication that complaints are unlikely [ref. BS 4142, Section 9]. 1 The Rating Level, as defined in BS 4142: 1997, is the specific noise level plus any adjustment for the characteristic features of the noise Dee Point Primary School Environmental Noise Report Page 5 of 14
Noise survey details Noise surveys have been carried out at the school to determine both the noise impact on the school, and to establish the existing background noise levels around the site. During attended noise surveys, the dominant noise source was considered to be road traffic on Sealand Road, to the south and west of the site. In addition, a number of aircraft were witnessed. 3.1 Jacobs noise assessment Initial noise surveys were carried out [by Jacobs] at the site on 23 rd April 2013. Noise levels were measured at two positions, as shown on the following Figure, between 09:00 and 15:00 hours. B A Figure 1 - Jacobs' measurement locations At the time of the Jacobs surveys and assessment, the precise location of the new school was unknown. It is also noted in the Jacobs notes that measurements were adversely affected by extraneous events, such as children playing in the play grounds. Activities within the school premises, including students within the building or in the playground are specifically to be excluded from calculations for the IANL [ref. Acoustic Performance Standards for the PSBP, Section 2.1.1]. Dee Point Primary School Environmental Noise Report Page 6 of 14
The following Table summarises the noise levels measured by Jacobs: Position Highest L Aeq,30mins A 58.1 B 51.2 Table 1 - Summary of Jacobs' measurement data It is noted that although the highest LAeq,30mins recorded was 58 dba, the average noise levels was only 52 dba. Based on the following graph, it can be seen that the highest measured noise levels coincide with lunchtime and afternoon outdoor activity periods. The following graph shows the change in noise level over a typical school day. 60 58 Jacobs' measured noise levels 56 Position A 54 Position B Sound Pressure Level, db L Aeq,30mins 52 50 48 46 44 42 40 09:00 09:30 10:00 10:30 11:00 11:30 12:00 12:30 13:00 13:30 14:00 14:30 15:00 Time Figure 2 - Typical daytime noise impact on the school 3.2 Cundall noise assessment Cundall have carried out short term monitoring in order to verify noise data. In addition, a night-time noise assessment has been carried out at the nearest noise sensitive premises, in order to establish the background noise level so that limiting noise levels for services plant can be set. Cundall carried out spot check noise measurements at the school on 9 th September 2014 [daytime] and 18 th September 2014 [night-time]. Measurements were carried out at three positions, as follows: Dee Point Primary School Environmental Noise Report Page 7 of 14
Position 1 was measured at a Position indicative of the noise impact on the southern façade of the new school; Position 2 was measured at a Position indicative of the northern façade of the new school; Position 3 was indicative of the nearest noise sensitive receptors, located off Tregele Close. The monitoring Positions are shown on the following image: 3 2 1 Figure 3 - Cundall measurement positions Measurements were carried out using a calibrated Norsonic 140 Class 1 sound level meter. The meter was calibrated prior to and immediately following measurements, with no significant drift noted. Copies of relevant calibration certification can be supplied upon request. The following Table summarises measurement data: Location / Period Highest L Aeq,30mins Lowest L A90,T Highest L Amax Position 1 [Daytime] 50.6 40.3 74.5 Position 2 [Daytime] 42.4 37.9 60.8 Position 3 [Night-time] N/A 29.1 N/A Table 2 - Summary of Cundall measurement data Based on the highest recorded 30 minute periods, it is noted that the Cundall and Jacobs data does not correlate well. However, as noted above, it is understood that the Jacobs data was adversely affected by outdoor student activities within the grounds. Taking Jacobs average LAeq,T of 52 dba over the daytime period [as opposed to the maximum] correlates very well with Cundall data. Dee Point Primary School Environmental Noise Report Page 8 of 14
Taking the noise data from both Jacobs and Cundall into consideration, it is considered that the highest noise impact on the school from external sources outside the school premises would be 55-56 dba. Dee Point Primary School Environmental Noise Report Page 9 of 14
Noise impact on the school As can be seen from Section 3 above, the site is subject to a relatively low noise impact. Calculations below for the attenuation requirements for glazing and ventilation have been based on a noise impact from external sources outside the school premises of 55-56 dba. 4.1 Glazing It is considered that for standard classbases that have an internal ambient noise level [IANL] requirement of 35 dba LAeq,T or greater, standard thermal double glazing will provide adequate sound insulation against external noise sources. A typical standard thermal double glazing configuration would be 4 mm pane / 16 mm air gap / 4 mm pane, which provides up to 25 db 2 Rw + Ctr sound reduction. It is recommended that any glazing to rooms with the more onerous IANL of no greater than 30 dba LAeq,T use a configuration such as 4 mm pane / 16 mm air gap / 4 mm, capable of 26 db 2 Rw + Ctr sound reduction. 4.2 Ventilation The ventilation strategy of Dee Point Primary School is to maximise the use of natural ventilation throughout the facility. Where a natural ventilation strategy is used, the upper limit for IANLs can be increased by up to 5 db, i.e. a standard classbase IANL would be 40 dba, instead of 35 dba LAeq,30mins. It is therefore considered that a naturally ventilated solution, utilising openable windows [providing up to 15 db attenuation] and standard Breathing Building units [that provide up to 26 db Dn,e,w] are acceptable where the external noise exposure is up to 56 dba LAeq,30mins. Any mechanical part of the ventilation strategy must comply with the IANL criteria, as set out in Table 1 of the Acoustic Performance Specification. 2 Ref. BS EN 12354-3:2000, Section B.2.1 Glazing Dee Point Primary School Environmental Noise Report Page 10 of 14
4.3 External walls / Roof construction 4.3.1 Noise break-in In order to ensure that external noise break-in is controlled, it is considered that the external wall and roof construction should provide a minimum sound reduction of at least 25 db Rw. This level of attenuation is achievable by means of most lightweight, masonry or concrete wall/roof constructions. 4.3.2 Rain impact noise Lightweight roofs and roof glazing will require suitable design so that they provide adequate control of rain noise such that the resultant reverberant sound pressure level in a space does not exceed 25 db above the appropriate IANL for the space. Dee Point Primary School Environmental Noise Report Page 11 of 14
Limiting noise levels for services plant In order to see that noise from new items of services plant does not increase the existing background noise levels, careful selection and positioning of plant should be considered. All new items of services plant should be designed and selected such that the rating level on the nearest noise sensitive premises [typically adjacent residential dwellings] does not exceed 10 db below the existing background noise levels. This is based on the methodology set out in BS 4142 and would be a positive indication that complaints are unlikely. 5.1 Nearest noise sensitive receptors The following Figure shows the nearest noise sensitive receptors to the school: Table 3 - Nearest noise sensitive receptors 5.2 Limiting noise levels The following Table summarises the existing background noise levels measured at the site, in addition to limiting noise levels for all new items of services plant, when measured at 1 m from the nearest noise sensitive receptor. Dee Point Primary School Environmental Noise Report Page 12 of 14
Period Existing background noise level, dba L A90,T Maximum sound pressure level [db L Aeq,T] when measured at 1 m from the nearest noise sensitive premises Daytime [07:00 to 23:00 hrs] 37.9 28 Night-time [23:00 to 07:00 hrs] 29.1 19 Table 4 - Limiting noise levels for services plant broad band data The following Tables show the octave band centre frequency [OBCF] data for measured existing noise levels and limiting noise levels. All values are in dba. DAYTIME - OBCF, Hz 63 125 250 500 1000 2000 4000 Existing background noise level, dba LA90,T 46.3 39.1 32.2 30.9 34.0 28.7 19.8 Maximum sound pressure level when measured at 1 m from the nearest noise sensitive premises 36 29 22 21 24 19 10 Table 5 Daytime limiting noise levels for services plant - octave band data NIGHT TIME - OBCF, Hz 63 125 250 500 1000 2000 4000 Existing background noise level, dba LA90,T 38.7 30.3 27.2 27.7 24.3 14.7 14.6 Maximum sound pressure level when measured at 1 m from the nearest noise sensitive premises 29 20 17 18 14 5 5 Table 6 Night-time limiting noise levels for services plant - octave band data The above limits apply to all services plant running simultaneously. Dee Point Primary School Environmental Noise Report Page 13 of 14
Cundall measurement data 6.1 Daytime Survey 11 th September 2014 Time L Aeq,30mins L AFmax L 90,30mins Position 1 13:17 48.2 67.7 40.3 13:47 50.6 74.5 40.6 Position 2 14:35 42.4 60.8 37.9 6.2 Night time Survey 18 th September 2014 Time L Aeq,5mins L AFmax L 90,5min Position 3 01:30 35.8 65.0 29.1 01:35 33.4 43.4 30.7 01:40 32.8 39.5 30.5 01:45 33.1 38.0 30.6 01:50 32.1 40.4 30.5 01:55 31.8 38.1 29.9 Dee Point Primary School Environmental Noise Report Page 14 of 14