Construction Noise and Vibration Assessment Report The ......WSP Environment & Energy Air Quality Assessment Report . QUALITY MANAGEMENT I WSP Environmental Limited WSP House 70 Chancery

Construction Noise and Vibration Assessment Report The Hasting Academy Client: Kier South East

Date: May 2011

WSP Environment & Energy

Air Quality Assessment Report

www.wspenvironmental.com

QUALITY MANAGEMENT

WSP Environmental Limited WSP House 70 Chancery Lane Holborn London WC2A 1AF Tel: +44 (0)20 7314 5000 Fax: +44 (0)20 7314 5111 www.wspenvironmental.com 1152332

Issue/revision Issue 1 Revision 1 Revision 2 Revision 3

Remarks FINAL

Date 23rd May 2011

Prepared by Chris Wood

Signature

Checked by Steve Fisher

Signature

Authorised by Martin

Raisborough

Signature

Project number 12104193

File reference Hasting Academy

Construction N&V

Report v1.2

(230511)

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WSP Environmental Ltd. Construction Noise & Vibration Assessment Report 3

1 INTRODUCTION

1.1 WSP Acoustics (a trading name of WSP Environmental Limited) has been appointed by Kier South East to undertake a noise and vibration impact assessment of the demolition of the Hillcrest School (excluding the Sports Centre) and the construction of the new Hastings Academy complex, for which planning permission was granted by East Sussex County Council in March 2011.

1.2 Accordingly, this report presents the details and finding of an assessment in accordance with British Standard (BS) 5228:2009 Code of practice for noise and vibration control on construction and open sites, and is thus compliant with Condition 8 of the Approval Notice and considered suitable for submission to the Director of Transport and Environment.

1.2.1 The details of Condition 8, together with Condition 7, which is also relevant to the assessment, are given in the following Section. The details of the assessment methodology and criteria are given in Section 3, whilst the baseline noise levels are described in Section 4 and the adopted noise criteria are given in Section 5. The adopted mitigation measures are then presented in Section 6 and the predicted noise and vibration levels are given in Sections 7 and 8 respectively. A Summary of the report and its findings is presented as the final section, Section 9.

1.2.2 This report is necessarily technical in nature and a glossary of terms can be found in Appendix A.

2 RELEVANT PLANNING CONDITIONS

2.1 CONDITION 7

2.1.1 Condition 7 states that, No demolition or construction shall take place in connection with the approved redevelopment at any time other than between 0730 and 1800 on Mondays to Fridays, between 0800 and 1800 on Saturdays and between 1000 and 1800 on Sundays, Bank and Public Holidays unless the prior written agreement of the Director of Transport and Environment has been given.

2.1.2 The ‘reason’ is given as: To help safeguard the amenities of the occupiers of properties in the vicinity of the site and to comply with Policy DG4 of the Hastings Local Plan 2004.

2.2 CONDITION 8

2.2.1 Condition 8 states that, Prior to commencement of development, an assessment of potential noise and vibration arising during construction shall be prepared in accordance with BS 5228-1:2009. The assessment shall be be [sic] submitted to and approved in writing by the Director of Transport and Environment and construction carried out in accordance with the agreed recommendations.

2.2.2 The ‘reason’ is given as: To help minimise the impact of construction on the local environment in accordance with Policy DG4 of the Hastings Local Plan 2004.

2.2.3 The relevant details of the Council’s Policy DG4 and BS 5228 are given in the following Section.


3 METHODOLOGY AND CRITERIA

3.1 HASTINGS LOCAL PLAN 2004

3.1.1 Policy DG4 Noisy Activities, which is one of the Local Plan 2004 policies to have been saved, is as follows:

Planning permission will not be granted for the proposals likely to result in unacceptable levels of noise. Where practicable, the Council will seek measures to attenuate noise levels, including:-

(a) Use of appropriate construction and insulating materials;

(b) Careful orientation of buildings and structures;

(c) Measures to control noise at source.

Where development is permitted, conditions restricting operating house and level of noise emission may be imposed.

3.2 BS 5228-1:2009 CODE OF PRACTICE FOR NOISE AND VIBRATION CONTROL ON CONSTRUCTION AND OPEN SITES – PART 1: NOISE

3.2.1 It is stated in Annex E of the Standard that, “Noise levels generated by construction activities are deemed to be significant if the total noise (pre-construction ambient plus construction noise) exceeds the pre-construction ambient noise by 5 dB or more, subject to lower cut-off values of 65 dB, 55 dB and 45 dB LAeq, Period, from construction noise alone, for the daytime, evening and night-time periods, respectively; and a duration of one month or more, unless works of a shorter duration are likely to result in significant impact.”

3.2.2 In addition to the above criterion, which is based on the change in ambient noise level, the Standard also presents fixed noise limits, which were typically used prior to the revision of the Standard (in 2009). The fixed noise limits, below, are applicable outside the windows of occupied rooms closest to the site boundary and should not exceed:

� 70 dB(A) in rural, suburban and urban areas away from main road traffic and industrial noise; or

� 75 dB(A) in urban areas near main roads in heavy industrial areas.

3.2.3 In WSP’s experience, a limit of 75 dB(A) has proved to represent the best compromise in the majority of instances; and a good indicator of the onset of complaints, assuming the residents are kept well informed of the works and are confident that all appropriate measures are being taken to keep levels to a minimum (such as those described later in this report). However, the new guidance in the current version of the Standard cannot be ignored, which is based on the reasonable expectation that the impact of construction noise will be greater in quieter environments, it is proposed to consider the predicted construction noise levels against both the sets of (change based and fixed) criteria.

3.2.4 Furthermore, the Standard also suggests that where, in spite of the mitigation measures applied, the combined construction and baseline noise levels exceed 75 dB(A) (for a period of ten or more days of working in any fifteen consecutive days or for a total of days exceeding 40 in any 6 month period), a scheme for the installation of noise insulation or the reasonable costs thereof will be implemented by the developer or promoter.

3.3 BS 5228-2:2009 CODE OF PRACTICE FOR NOISE AND VIBRATION CONTROL ON CONSTRUCTION AND OPEN SITES – PART 2: VIBRATION

3.3.1 With respect to human exposure to building vibration, Table B1 of Annex B to BS 5228-2:2009 (Part 2: Vibration) provides guidance on the effects of vibration levels on human beings and it is these that are reproduced in Table 1 and that the construction vibration effects has been based upon.


Table 1: Guidance on effects of vibration levels

Vibration level Effect

0.14 mm·s−1 Vibration might be just perceptible in the most sensitive situations for most vibration frequencies associated with construction. At lower frequencies, people are less sensitive to vibration.

0.3 mm·s−1 Vibration might be just perceptible in residential environments.

1.0 mm·s−1 It is likely that vibration of this level in residential environments will cause complaint, but can be tolerated if prior warning and explanation has been given to residents.

10 mm·s−1 Vibration is likely to be intolerable for any more than a very brief exposure to this level.

3.3.2 Guide values for cosmetic damage to buildings are given in Table B.2 of the Standard and this is reproduced below as Table 2, together with Figure B.1 (Figure 1 below) to which it refers:

Table 2: Transient vibration guide values for cosmetic damage

Line (see Figure 1) Type of building

Peak component particle velocity in frequency range of predominant pulse

4 Hz to 15 Hz 15 Hz and above

1

Reinforced or framed structures

Industrial and heavy commercial buildings

50 mm·s−1 at 4 Hz and above 50 mm·s−1 at 4 Hz and above

2

Unreinforced or light framed structures

Residential or light commercial buildings

15 mm·s−1 at 4 Hz increasing to 20 mm·s−1 at 15 Hz

20 mm·s−1 at 15 Hz increasing to 50 mm·s−1 at 40 Hz and above

NOTE 1 Values referred to are at the base of the building.

NOTE 2 For line 2, at frequencies below 4 Hz, a maximum displacement of 0.6 mm (zero to peak) is not to be exceeded.

Figure 1: Transient vibration guide values for cosmetic damage


4 BASELINE NOISE LEVELS

4.1 MEASURED NOISE LEVELS

4.1.1 In accordance with the latest version of BS 5228-1:2009, as described above, it is appropriate to determine the existing, pre-construction noise levels at the nearest receptors for the purpose of defining suitable criteria for the assessment of the significance of the predicted construction noise levels.

4.1.2 Accordingly, the data obtained during an environmental noise survey conducted by WSP at the site from Wednesday 2nd to Monday 7th of June 2010 has been used for this purpose.

4.1.3 The measurements were made at 1 m from the first floor façade of the existing school, closest to Rye Lane. In accordance with the time periods specified in Condition 7, as reproduced in Section 2 of this report, and the criteria presented in BS 5228-1:2009, the results have been post-processed to determine the LAeq,T noise levels at the measurement location. The results are as follows, which include the logarithmic average of the weekday noise levels:

Wednesday 2nd June 2010: 60.7 dB LAeq,10hr (08:00 to 18:00 hours)

Thursday 3rd June 2010: 60.5 dB LAeq,10hr (08:00 to 18:00 hours)

Friday 4th June 2010: 59.8 dB LAeq,10hr (08:00 to 18:00 hours)

Saturday 5th June 2010: 59.7 dB LAeq,10hr (08:00 to 18:00 hours)

Sunday 6th June 2010: 60.9 dB LAeq,8hr (10:00 to 18:00 hours)

Weekday Logarithmic Average: 60.4 dB LAeq,10hr (08:00 to 18:00 hours)

4.1.4 It can be seen that there is barely more than a dB between the above noise levels, indicating that the noise environment, in terms of the 10 hour period between 08:00 and 18:00 hours at least, are very consistent. This is considered to be due to consistent road traffic flow levels and suggests a robust and indicative dataset.

4.2 NEAREST NOISE-SENSTIVE RECEPTORS

4.2.1 The nearest noise-sensitive receptors are the dwellings on Rye Road, Churchill Avenue and Winchelsea Lane, which can be seen on the following aerial image.

Figure 2: Aerial photograph showing the existing school buildings and the nearest noise-sensitive receptors (i.e. dwellings)

Existing School Buildings

Dwellings on Winchelsea Lane

Dwellings on Rye Road

(opposite site)

Dwellings on Rye Road

(adjacent site) © 2010 Intermap © AND © 2010 NAVTEQ © 2011 Microsoft Corporation C) 2010 Blom


4.3 BASELINE NOISE LEVELS AT THE NEAREST NOISE-SENSITIVE RECEPTORS

4.3.1 To determine the equivalent noise levels outside the dwellings identified in Figure 1, 3D noise mapping software (CadnaA) has been used. The model has been ‘calibrated’ such that the noise level predicted at the measurement location is the same as the noise logarithmic average of the weekday LAeq,10hr noise levels measured during the survey, which, as shown above, has been found to be 60 dB (façade). This level is also the same as the recorded for the Saturday and essential the same as that recorded for the Sunday. In fact, the Sunday noise level is slightly higher than the average, 0.4 dB, or 1 dB in round terms, such that using the lower, average level represents worst case.

4.3.2 For the dwellings identified above, the following baseline noise levels have been determined:

Dwellings on Rye Road (adjacent site) – rear façade: 45 dB LAeq,,T

Dwellings on Rye Road (opposite site) – front façade: 63 dB LAeq,T

Dwellings on Winchelsea Lane – front facade: 62 dB LAeq,T

Where ‘T’ is either the 10 hour period between 08:00 and 18:00 hours, which is applicable to weekdays and Saturdays, or the 8 hour period between 10:00 and 18:00 hours, which is applicable to Sundays and Bank Holidays, as per Condition 7.

4.4 BASELINE VIBRATION LEVELS

4.4.1 Baseline vibration levels are not required for this assessment.

5 ADOPTED NOISE CRITERIA

5.1 Based on the baseline noise levels described above and the guidance in BS 5228-1:2009, the following criteria have been adopted for this assessment:

Dwellings on Rye Road (adjacent site) – rear façade: 65 dB LAeq,,T (combined noise level)

Dwellings on Rye Road (opposite site) – front façade: 68 dB LAeq,T (combined noise level)

Dwellings on Winchelsea Lane – front facade: 67 dB LAeq,T (combined noise level)

5.2 In addition to which, and as discussed in Section 3, it is considered appropriate to also considered the predicted construction noise levels against the fixed noise levels of 70 and 75 dB(A).

6 MITIGATION MEASURES

6.1 In the first instance, the core working hours will be limited to those specified in Condition 7:

• 07:30 - 18:00 hours weekdays;

• 08:00 – 18:00 hours Saturdays; and

• 10:00 - 18:00 hours Saturday and Bank Holidays.


6.2 These hours will be strictly adhered to, unless:

• an emergency demands continuation of works on the grounds of safety;

• fitting out works are being carried out within the containment of the building envelope; or

• completion of an operation that would otherwise cause greater interference with the environment/general public if left unfinished.

6.3 Best Practicable Means (BPM) of preventing, reducing and minimising noise will be adopted.

6.4 Good practice procedures will be followed in order to mitigate noise, vibration and air pollution (e.g. through dust and fume-generation) effects. Measures currently planned include:

• the contractor will comply with the requirements of the Control of Pollution Act 1974, with particular reference to Part III, the Environmental Protection Act 1990, The Control of Noise at Work Regulations 2005 and the Health and Safety at Work etc. Act 1974;

• leaflets giving an overview of works and providing dates and durations of the key activities will be distributed to dwellings within at least 100 m of the site boundary;

• noticeboards will be erected displaying clearly the name of the Principle Contactor and 24 hour contact details;

• all plant and equipment to be used for the works will be properly maintained, silenced where appropriate, and operated to prevent excessive noise and switched off when not in use and where practicable;

• hydraulic demolition and construction will be used in preference to percussive techniques where practical;

• the contractor will erect and maintain throughout construction works a temporary barrier along the southern and western boundaries of the southern section of the site, along the haul route to the fill area. The barrier will be at least 2 m high and possess a surface density of at least 7 kg/m2 and no holes or gaps;

• plant will be certified to meet relevant current legislation and selected to be no noisier than similar examples cited in BS 5228:2009 Code of practice for noise and vibration control on construction and open sites, Parts 1 Noise and 2 Vibration;

• all trade contractors will be made familiar with current noise legislation and the guidance in BS 5228:2009 (Parts 1 and 2) which will form a prerequisite of their appointment;

• Ad-hoc noise monitoring will be undertaken as required;

• loading and unloading of vehicles, dismantling of equipment such as scaffolding or moving equipment or materials around the site will be conducted in such a manner as to minimise noise generation;

• deviation from approved method statements will be permitted only with prior approval from the Principal Contractor and other relevant parties. This will be facilitated by formal review before any deviation is undertaken; and

• any complaints received by the Contractor will be immediately investigated.


7 PREDICTED NOISE LEVELS

7.1 PROGRAMME

7.1.1 Based on the Contract Programme (No. 7076/CP/01m Revision B, dated 04/04/2011) issued to WSP by Kier, the following key events have been identified:

� Decant and Initial Enabling Works (April to June 2011): including the establishment of temporary teaching accommodation, refurbishment of existing cabins, decant into these spaces, and establishment of site accommodation, storage areas, Heras fencing and hoarding, and pedestrian and traffic routes

� Construction Phase 1 – Construct New Academy (20th June 2011 to 18th February 2013)

� Site Possession (20th June 2011)

� Enabling Works (20th June to 2nd September 2011): including establishment of additional fencing and site accommodation

� Demolition and Form Access Road (20th June to 2nd September 2011): including soft and hard strip of existing school and sports hall and removal of foundations, excavation and formation of access roads and haul routes

� Substructure Construction (29th August to 9th December 2011): including excavation and formation of structurally reinforced concrete foundations for shear walls, pad foundations and ground floor slabs, for the following buildings/buildings elements:

� North Wing (29th August to 25th November 2011)

� Central Area (5th September to 4th November 2011)

� South Wing (5th September to 4th November 2011)

� External Plant Rooms (17th October to 11th November 2011)

� Superstructure Construction (31st October 2011 to 24th February 2012): including formation of structurally reinforced concrete internal and external walls, floors, columns and roofs, for the following buildings/building elements:

� North Wing (21st November 2011 to 10th February 2012)

� Central Area (31st October 2011 to 24th February 2012)

� South Wing (5th December 2011 to 24th February 2012)

� External Plant Rooms (19th December 2011 to 17th February 2012)

� Erection of Tower Cranes 1 and 2 (24th and 31st October 2011)

� Dismantling of Tower Cranes 1 and 2 (27th February 2012)

� External Works and Additional Demolition Works (16th July 2012 to 18th January 2013): including hard and soft landscaping, installation of new temporary site accommodation and demolition of Language Building (1st to 26th October 2012)

� The Hasting Academy Opens (18th February 2013)

� Construction Phase 2 – Demolition / External Works (23rd July 2012 to 30th August 2013).

� Possession of Existing School (4th February 2013)

� Site Establishment (4th to 22nd February 2013): including establishment of fencing and site accommodation

� Demolition (18th February to 12th April 2013): including soft and hard strip of existing school and removal of foundations


� External Works (18th February to 30th August 2013): including soft landscaping, removal of temporary classrooms, formation of access roads and car parking

7.1.2 Further to the above, the key activities with respect to noise and vibration have been taken to be:

� Demolition

� Excavation and groundworks

� Movement of excavated material to fill area (along sports field)

� Activity within the fill area

� Foundation and substructure works

� Superstructure works

� Infrastructure and landscaping works

7.2 PLANT DETAILS

7.2.1 For the key activities identified above, the plant and associated sound power levels assumed for the predictions are given in the table below along with a reference to the origin of this source information from Annexes C and D of BS 5228-1:2009.

Table 4: Construction plant sound power levels and percentage on-time

Plant Data source LWA (dB) (each item) % on-time per day

Demolition

1 no. 50T long reach excavator BS 5228 - C.2/14 107 50

3 no. 20T dump trucks BS 5228 - C.2/30 107 50

1 no. 20T excavator BS 5228 - C.2/21 99 50

1 no. 20T excavator with breaker BS 5228 - C.1/9 118 20

1 no. crusher BS 5228 - C.1/14 110 50

Excavation and groundworks



2 no. 20T excavators BS 5228 - C.2/21 99 60


Movement of excavated material to fill area (along sports field)

2 no. 30T dump trucks BS 5228 - C.2/30 107 60

Activity within the fill area

2 no. D6 Dozers (grading and towing sheepsfoot compactor) BS 5228 - D.3/74 105 60


2 no. 30T dump trucks BS 5228 - C.2/30 107 60 Note: “% On-Time” is the percentage of the working day over which the plant is assumed to be operating.

Table continued/…


Table 4: Construction plant sound power levels and percentage on-time continued/…

Plant Data source LWA (dB) (each item) % on-time per day

Foundation and substructure works


1 no. dumper lorry tipping BS 5228 - C.2/30 107 30

Several concrete mixer truck discharging BS 5228 - C.4/18 103 20

1 no. concrete pump BS 5228 - D.6/17 109 20

5 no. poker vibrators BS 5228 - D.6/20 102 10

Shuttering erection BS 5228 - D.7/80 107 20

Superstructure works

2 no. tower cranes BS 5228 - C.4/48 104 20


1 no. concrete pump BS 5228 - C.4/32 106 30

2 no. forklift trucks BS 5228 - D.7/93 104 30

hammering BS 5228 - D.7/80 107 2

scaffolding erection/dismantling BS 5288 - D.7/1 108 20

Several lorries delivering materials BS 5228 - C.2/34 108 5

Infrastructure and Landscaping

2 no. 20T excavators BS 5228 - C.2/21 99 50


1 no. concrete pump BS 5228 - C.4/32 106 30

hammering BS 5228 - D.7/80 107 2

1 no. petrol hand-held circular saw BS 5228 - C.4/73 112 2

1 no. asphalt paver and tipper lorry BS 5228 - C.5/31 105 50

1 no. vibratory roller BS 5228 - C.5/26 & 28 105 50

1 no. pneumatic breaker BS 5228 - D.8/1 114 2 Note: “% On-Time” is the percentage of the working day over which the plant is assumed to be operating.

Predictions

7.2.2 For the purpose of the predictions, it is assumed that the intervening ground between the construction noise sources and the noise-sensitive properties, for both the ‘worst case’ and ‘average case’ scenarios, will be acoustically hard such that there will be no significant attenuation of sound due to ground absorption. It also has been assumed that there will be a continuous site hoarding on the southern and western boundaries of the southern section of the site, along the haul route to the fill area, 2.4 m high.

7.2.3 The predictions have been undertaken for the closest noise-sensitive receptors (dwellings) identified earlier, and as listed in Table 5, together with the distances to the key activities associated with Construction Phases 1 and 2.


Table 5: Distances to nearest receptors from construction works

Activity

Distances to nearest receptors from construction works (m)

Dwellings on Rye Road (adjacent site),

rear façade

Phase 1 / 2

Dwellings on Rye Road (opposite site),

front façade

Phase 1 / 2

Dwellings on Winchelsea Lane,

front façade

Phase 1 / 2

Demolition 30 / 50 60 / 55 200 / 65

Excavation and ground works 30 / 80 60 / 55 200 / 80

Movement of excavated material 40 / N/A 90 / N/A 270 / N/A

Activity in fill area 50 / N/A 110 / N/A 300 / N/A

Foundation and substructure works 80 / N/A 100 / N/A 200 / N/A

Superstructure works 80 / N/A 100 / N/A 200 / N/A

Infrastructure and landscaping 80 / 80 100 / 55 200 / 80

7.2.4 Based on the distances in Table 5 and the programme, activities and plant described, the predicted façade construction noise levels are set out in the following table.

Table 6: Predicted construction noise levels – LAeq,T dB

Activity

Predicted Construction Noise Levels, LAeq,T (dB)


rear façade Phase 1 / 2


front façade Phase 1 / 2


front façade Phase 1 / 2

Demolition 70 / 66 64 / 75 54 / 73







7.3 COMPARISON WITH THE ADOPTED CRITERIA

7.3.1 The adopted criteria given in paragraph 5.1 are applicable to the combination of the construction noise levels with the baseline noise levels. The resultant combined noise levels are presented in the table below.


Table 7: Combined baseline and predicted construction noise levels – LAeq,T dB

Activity

Combined Baseline and Construction Noise Levels, LAeq,T (dB)


rear façade

Phase 1 / 2


front façade

Phase 1 / 2


front façade

Phase 1 / 2

Demolition 75 / 66 68 / 75 63 / 73







Adopted Criteria 65-70-75 68-70-75 67-70-75

7.3.2 It can be seen from the above that:

7.4 DWELLINGS ON RYE ROAD (ADJACENT SITE)

� The “change” criterion of 65 dB is likely to be exceeded during the Phase 1 & 2 demolition works and the Phase 1 activity in the fill area only

� The lower “fixed” criterion is likely to be exceeded during the Phase 1 demolition works only

� The upper “fixed” criterion is likely to be met during all key phases of work

� None of the dwellings described above are eligible for noise insulation

7.5 DWELLINGS ON RYE ROAD (OPPOSITE SITE)

� The “change” criterion of 68 dB is likely to be exceeded during the Phase 2 demolition and infrastructure and landscaping works only.




7.6 DWELLINGS ON WINCHELSEA LANE

� The “change” criterion of 67 dB is likely to be exceeded during the Phase 2 demolition works only




7.7 SUMMARY

7.7.1 It is inevitable with any development that there will be some disturbance caused to those nearby during the site clearance, demolition and construction works; and the works associated with the proposed development are on a reasonable scale, whilst some of the nearest receptors are particularly close. It is not surprising, therefore, that despite the mitigation measures to be adopted, which are considered to represent BPM, the criteria that have derived based on a 5 dB uplift in the pre-construction baseline noise levels, with a lower limit of 65 dB, are likely to be exceeded during some phases of works, potentially all key phases at the very nearest dwelling(s). Which, according to BS 5228, could represent significant impacts.


7.7.2 However, in WSP’s experience, and where the residents are provided with sufficient information, and thus given confidence that mitigation measures are in place, complaints are not typically received until construction noise levels exceed 75 dB (LAeq,10hr). This is also the threshold adopted by BS 5228 above which it may be necessary to provide the receptor with noise insulation (e.g. secondary glazing), but which is unlikely to be exceeded, not for any prolonged period in any case, such that no dwellings have been found to be eligible for sound insulation.

7.8 ADDITIONAL MITIGATION MEASURES

7.9 It is considered that no additional mitigation measures are necessary. Notwithstanding this, the construction site management must be vigilant at all times in this regard to ensure that BPM are being adopted at all times, and that adjustments to plant, techniques and screening etc. are made where necessary.

8 PREDICTED VIBRATION LEVELS

8.1 For the purposes of calculating the vibration effect from the key demolition and construction works, measurement data have been taken from measurements undertaken by WSP at other sites. The most significant source of vibration will be the hydraulic breakers deployed for the removal of areas of hardstanding and the foundations of the existing structures. The next most significant source will be the excavators used during the excavation, ground works, where the vibration doesn’t so much come from the use of the bucket, but from the weight of the excavator itself as it is manoeuvred.

8.2 The predictions have been undertaken for the same receptors as considered in the noise predictions. The relevant distances are as follows:

Table 8: Distances to nearest receptors from construction works

Activity

Distances to nearest receptors from construction works (m)

Dwellings on Rye Road (adjacent site)

Phase 1 / 2

Dwellings on Rye Road (opposite site)

Phase 1 / 2


Phase 1 / 2

Demolition 30 / 50 60 / 55 200 / 65


8.3 The predicted maximum PPV levels of vibration at each of the vibration-sensitive receptors are detailed in Table 9. The predicted vibration levels are those that would occur when the works are being undertaken at the closest point to each of the sensitive receptors (as assumed for the noise predictions) and, therefore, represent a worst case scenario.

Table 9: Predicted PPV vibration levels on internal floors (within the nearest receptors)

Activity

Predicted PPV (mm/s)

Dwellings on Rye Road (adjacent site)

Phase 1 / 2

Dwellings on Rye Road (opposite site)

Phase 1 / 2


Phase 1 / 2

Hydraulic breaker 0.83 / 0.50 0.42 / 0.45 0.12 / 0.38

Excavation 0.67 / 0.25 0.33 / 0.36 0.10 / 0.25


8.4 It can be seen from Table 9 above that the predicted vibration levels are below 1 mm/s, at which level BS 5228-2:2009 states that, “It is likely that vibration of this level in residential environments will cause complaint, but can be tolerated if prior warning and explanation has been given to residents.” Accordingly, it is considered that complaints about vibration are unlikely, especially where sufficient information is provided to the residents, which it will be as part of the mitigation measures.

9 SUMMARY

9.1 In accordance with the procedures contained in BS 5228:2009 parts 1 and 2, and in keeping with the requirements of Condition 8 attached to the permission to construct the new Hastings Academy complex, an assessment has been undertaken to determine the likely noise (and vibration) levels during the key demolition and construction activities associated with the proposed development.

9.2 In accordance with BS 5228-1:2009, two sets of noise criteria have been adopted that take into account the significance of a change in the pre-construction baseline noise levels as well as absolute noise limits that have worked well in WSP’s experience, and, according to the Standard, represent the threshold above which there may be a need to provide the affected receptors with noise insulation.

9.3 Inevitably, given the scale of the works and the proximity of some of the neighbouring dwellings, it has been found that the combined baseline and construction noise levels are likely to exceed the pre-construction noise levels by 5 dB or more at times, such that, according to the Standard, significant impacts could be experienced by the affected occupants. However, it has also been found that the upper, fixed limit, which has worked well in WSP’s experienced, is unlikely to be exceeded, which also means that no dwellings would be eligible for noise insulation.

9.4 Accordingly, whilst significant noise impacts may be experienced by some receptors at times during the works, any such effects are expected to be no more than can reasonably be expected from such works under the circumstances, and that no further mitigation measures are required.

9.5 The assessment of vibration levels during the demolition and excavation activities has found that complaints are unlikely, especially where the residents are given sufficient information, which will be provided as part of the mitigation strategy.

9.6 It must be borne in mind that the assessment is based on the adoption of the mitigation measures described in Section 6 of this report, and that, regardless of noise levels, BPM must be adopted at all times, which will require a proactive approach by the site management.

WSP Acoustics


Appendix A Glossary of Terms


Noise

Noise is defined as unwanted sound. Human hearing is able to respond to sound in the frequency range 20Hz (deep bass) to 20,000Hz (high treble) and over the audible range of 0dB (the threshold of perception) to 140dB (the threshold of pain). The ear does not respond equally to different frequencies of the same magnitude, but is more responsive to mid-frequencies than to lower or higher frequencies. To quantify noise in a manner that approximates the response of the human ear, a weighting mechanism is used, which reduces the importance of lower and higher frequencies in a similar manner to human hearing.

The weighting mechanism that best corresponds to the response of the human ear is the ‘A’-weighting scale. This is widely used for environmental noise measurement, and the levels are denoted as dB(A) or LAeq, LA90 etc, according to the parameter being measured. The Glossary explains the acoustic terminology that is used in this Report.

The decibel scale is logarithmic rather than linear, and hence a 3 dB increase in sound level represents a doubling of the sound energy present. Judgement of sound is subjective, but as a general guide a 10 dB(A) increase can be taken to represent a doubling of loudness, whilst an increase in the order of 3 dB(A) is generally regarded as the minimum difference needed to perceive a change under normal listening conditions.

An indication of the range of sound levels found commonly in the environment is given in the table below.

Typical sound levels found in the environment

Sound Pressure Level, dB(A) Location

0 Threshold of hearing

20 to 30 Quiet bedroom at night

30 to 40 Living room during the day

40 to 50 Typical office

50 to 60 Inside a car

60 to 70 Typical high street

70 to 90 Inside factory

100 to 110 Burglar alarm at 1 m away

110 to 130 Jet aircraft on take off

140 Threshold of pain

The subjective response to a noise is dependent not only upon the sound pressure level and its frequency, but also its intermittency. Various indices have been developed to try and correlate annoyances with the noise level and its fluctuations. The indices and parameters used in this report are defined below:

Sound Pressure: Sound, or sound pressure, is a fluctuation in air pressure over the static ambient pressure.

Sound Pressure Level (Sound Level): The sound level is the sound pressure relative to a standard reference pressure of 20Pa (20x10-6 Pascals) on a decibel scale.

Decibel (dB): A scale for comparing the ratios of two quantities, including sound pressure and sound power. The difference in level between two sounds s1 and s2 is given by 20 log10 (s1/s2). The decibel can also be used to measure absolute quantities by specifying a reference value that fixes one point on the scale. For sound pressure, the reference value is 20Pa.

A-weighting, dB(A): The unit of sound level, weighted according to the A-scale, which takes into account the increased sensitivity of the human ear at some frequencies.


Noise Level Indices: Noise levels usually fluctuate over time, so it is often necessary to consider an average or statistical noise level. This can be done in several ways, so a number of different noise indices have been defined, according to how the averaging or statistics are carried out.

Equivalent Continuous Sound Pressure Level (LAeq): The A-weighted sound pressure level of a steady sound that has, over a given period, the same energy as the fluctuating sound under investigation.

Façade: At a distance of 1m in front of a large sound reflecting object such as a building façade.

Vibration

Vibration is defined as a repetitive oscillatory motion. Groundborne vibration can be transmitted to the human body through the supporting surfaces; the feet of a standing person, the buttocks, back and feet of a seated person or the supporting area of a recumbent person. In most situations, entry into the human body will be through the supporting ground or through the supporting floors of a building. Vibration from road traffic can also be airborne. Such airborne vibration is transmitted as a low-frequency sound wave and is often perceived when the sound wave causes windows or other objects to rattle.

Vibration is often complex, containing many frequencies, occurring in many directions and changing over time. There are many factors that influence human response to vibration. Physical factors include vibration magnitude, vibration frequency, vibration axis, duration, point of entry into the human body and posture of the human body. Other factors include the exposed persons experience, expectation, arousal and activity.

Experience shows that disturbance or annoyance from vibration in residential situations is likely to arise when the magnitude of vibration is only slightly in excess of the threshold of perception.

The threshold of perception depends on the frequency of vibration. The human body is most sensitive to vibration in the frequency range 1 to 80 Hz and especially sensitive to vibration in the range 4 to 8 Hz. As with noise, a frequency weighting mechanism is used to quantify vibration in a way that best corresponds to the frequency response of the human body. In general, vibration is only perceptible in residential situations when the building is close to a railway, construction site or very close to a road that carries large and heavy vehicles.

Displacement, Acceleration and Velocity; Root Mean Square (r.m.s.) and Peak Values; and Peak Particle Velocity (PPV): Vibration is an oscillatory motion. The magnitude of vibration can be defined in terms of displacement (how far from the equilibrium position that something moves), velocity (how fast something moves), or acceleration (the rate of change of velocity). When describing vibration, one must specify whether peak values are used (i.e. the maximum displacement or maximum velocity) or r.m.s. / r.m.q. values (effectively an average value) are used. Standards for the assessment of building damage are usually given in terms of peak velocity (usually referred to as Peak Particle Velocity, or PPV), whilst human response to vibration is often described in terms of r.m.s. or r.m.q. acceleration.

Root Mean Square (r.m.s.): The r.m.s. value of a set of numbers is the square root of the average of the squares of the numbers. For a sound or vibration waveform, the r.m.s. value over a given time period is the square root of the average value of the square of the waveform over that time period.

Root Mean Quad (r.m.q.): The r.m.q. value of a set of numbers is the fourth root of the average of the fourth powers of the numbers. For a vibration waveform, the r.m.q. value over a given time period is the fourth root of the average value of the fourth power of the waveform over that time period.

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Construction Noise and Vibration Assessment Report The ......WSP Environment & Energy Air Quality Assessment Report . QUALITY MANAGEMENT I WSP Environmental Limited WSP House 70 Chancery