TESCO CAR WASH, HAZELWICK AVENUE, CRAWLEY ACOUSTICS REPORT ... · rpsgroup.com 4th april 2013 tesco car wash, hazelwick avenue, crawley acoustics report on the potential noise impact

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4th April 2013

TESCO CAR WASH, HAZELWICK AVENUE, CRAWLEY

ACOUSTICS REPORT ON THE

POTENTIAL NOISE IMPACT OF A PROPOSED CAR WASH ON NEARBY

RESIDENTIAL RECEPTORS

Our Ref: B7133/ENV/P1 RPS Highfield House, 5 Ridgeway, Quinton Business Park, Birmingham, B32 1AF Tel: 0121 213 5500 Fax: 0121 213 5502 Email: [email protected]

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QUALITY MANAGEMENT

Prepared by: P A Kelly

Authorised by: R J Turner

Date: 4th

April 2013

Project Number/Document Reference:

B7133/ENV/P1

COPYRIGHT © RPS

The material presented in this report is confidential. This report has been prepared for the exclusive use of Gilmore Consultancy Ltd

and shall not be distributed or made available to any other company or person without the knowledge and written consent of RPS.

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CONTENTS

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

2 ASSESSMENT CRITERIA ...................................................................................................................... 2

3 ENVIRONMENTAL NOISE - CRAWLEY ............................................................................................... 4

4 SPECIFIC NOISE – DUDLEY, CHELTENHAM & BRISTOL ................................................................. 7

5 3D NOISE MODEL .................................................................................................................................. 9

6 BS 4142 CALCULATION ..................................................................................................................... 12

7 OUTDOOR AMENITY SPACES ........................................................................................................... 13

8 CONCLUSIONS .................................................................................................................................... 14

APPENDIX 1 – SITE PLAN SHOWING APPROXIMATE MEASUREMENT POSITION............................... 15

APPENDIX 2 – MEASUREMENT RESULTS ................................................................................................. 16

APPENDIX 3 – 3D NOISE MODEL ................................................................................................................ 17

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1 INTRODUCTION

1.1 RPS (Acoustics) has been commissioned by Gilmore Consultancy Ltd. to carry out an

assessment of the potential noise impact generated by a car washing facility proposed at the

Tesco Extra Crawley Hazelwick Superstore, Hazelwick Avenue, on nearby residential properties

and a temporary school building.

1.2 The proposed location for the car washing facility is to the east of the existing Tesco Extra

Superstore adjacent to the northern boundary of the associated car park.

1.3 The purpose of this report is to evaluate prevailing noise levels at the existing residential

properties and the temporary school building, compare these against known noise levels

generated by the car washing operation, and determine the likely noise impact and suggest

mitigation measures if required.

1.4 Measured noise levels of existing car wash operations at Tesco stores in Dudley, Cheltenham

and Bristol have been used in order to predict the noise impact at the nearest residential

properties and temporary school building.

1.5 It is understood that the car washing facility will operate during daytime hours only.

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2 ASSESSMENT CRITERIA

2.1 This Report uses guidance from the following standards and documents:

� BS 8233:1999, ‘Sound Insulation and Noise Reduction for Buildings – Code of Practice’

� W.H.O:1999 ‘Guidelines for Community Noise’

� BS 4142:1997, ‘Method for rating industrial noise affecting mixed residential and industrial

areas’

a) BS 8233:1999 / W.H.O Guidelines

2.2 BS 8233 states that it is desirable that the steady noise level in external amenity areas (such as

gardens or outdoor living areas) should “not exceed 50 dB LAeq,T and 55 dB LAeq,T should be

regarded as the upper limit.” This is in line with recommendations given in the WHO Guidelines

for Community Noise.

b) BS 4142: 1997

2.3 BS 4142:1997 provides a method to determine whether an industrial noise source introduced into

a residential area is likely to give rise to complaints.

2.4 The likelihood of complaints is assessed by subtracting the measured background noise level at

the proposed site (at a location representative of the nearest residential property) from the ‘Rating

level’ (the specific noise source to be introduced into the locality, in addition to corrections made

for tonality etc).

2.5 The greater this difference, the greater the likelihood of complaints. BS 4142 states that:

� if the Rating level is 10 dB or more above the measured background level then this is an

indication that complaints are likely

� if the Rating level is around 5 dB above the background level, this is of marginal significance

� if the Rating level is 10 dB or more below the background level, this is a positive indication

that complaints are unlikely.

2.6 Guidance given in BS 4142 states1 that the specific noise level (the noise source under

investigation for assessing the likelihood of complaints) should be evaluated over the appropriate

time reference interval, namely:

� 1 hour during the day, and

� 5 minutes at night.

1 BS 4142: 1997, Section 6.2.

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c) Crawley Borough Council

2.7 The requirements of Crawley Borough Council (CBC) Environmental Health Department were

agreed between Davie Walkes2 of CBC and RPS as part of the Planning Application process, and

are reproduced below for clarity:

� An environmental noise survey will be conducted during the quietest period of a week* in

which the car wash will be operational.

� The environmental noise survey will be carried out at the following two positions:

o As close as possible to the rear garden of the nearest residential dwelling (Hazelwick

Avenue).

o At the Tesco car park boundary as close as possible to temporary classrooms at

Hazelwick School to the north of the site.

� Existing noise data from the specific noise levels of each item of equipment will be used to

assess the potential noise impact on the nearest residential dwelling. Data for specific noise

measurements will be included within the report.

� RPS would build a detailed 3D computer noise model of the proposed site and surrounding

area (including nearest noise-sensitive receivers).

� The noise impact of the car wash would be assessed against the lowest measured

background noise levels (LA90,T).

� If the noise impact of the car wash was ≥ 5 dB lower than the existing LA90,T then it would be

assumed that the noise impact would be negligible and there would be no objection to the

application on the ground of noise impact.

*from previous surveys, it has been found that this is typically on a weekday between the

hours of 10:00 and 12:00

2 Ref: Telephone call between M Pimlott of RPS and Davie Walkes of CBC and subsequent e-mail from M

Pimlott to Davie Walkes – 27/03/2013

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3 ENVIRONMENTAL NOISE - CRAWLEY

a) Site

3.1 The Tesco site is located in a mixed use area to the north east of the centre of Crawley. To the

north of the site is Hazelwick Comprehensive School and associated playing fields. Temporary

buildings associated with the school are considered to be the nearest noise sensitive properties

to the proposed car wash. These are separated from the site by playing fields and an

approximately 3 m high brick wall along the northern boundary of the Tesco car park.

3.2 To the west, south-west and south of the site lies Hazelwick Avenue which borders a residential

area. Dwelling houses on The Birches are considered to be the nearest residential properties to

the proposed carwash.

3.3 Tesco Extra superstore is directly to the east of the proposed carwash.

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b) Measurements

3.4 Attended measurements were carried out over the following time period:

� Thursday 28th March 2013 – between approximately 10:02 - 12:04 hours

3.5 The daytime period monitored is considered to be representative of prevailing conditions during

the quietest hours of proposed car wash operations.

3.6 The measurement positions selected for the surveys were as close as possible to the noise

sensitive receptors identified by CBC, and are shown on the site plan given in Appendix 1.

3.7 Noise descriptors measured were as follows:

� LAeq,T, the average A-weighted noise level over each measurement period

� LA90,T, the A-weighted noise level exceeded for 90% of the measurement period

3.8 Noise measurements were made using a Class 1 Svan 949 sound level meter, generally in

accordance with BS EN 60651:1994 and BS 7445:1993.

3.9 The meters were calibrated before and after each use and no significant drift was witnessed.

3.10 Copies of the relevant calibration certificates associated with the meter are available upon

request.

3.11 Local weather conditions for the duration of the surveys were overcast with temperatures of 2o C.

The maximum measured wind speed during the survey did not exceed 5 m/s.

3.12 The time period, T, was set to 5 minutes for the duration of the survey.

c) Results

3.13 Table 1 shows the results of the survey. All measurements are in dB(A) and have been rounded

to the nearest integer value, as fractions of a decibel are imperceptible:

Measurement Position Location Averaged

LAeq,T

Highest

LAF,max

Lowest

LA90,T

Weekday Daytime Period (28th

March 2013 – between approximately 10:00 -12:00 hours)

Position 1 Representative of temporary school building

58.3 96.9 49.2

Position 2 Nearest residential properties (The Birches)

71.5 85.6 60.2

Table 1 – Attended Survey Noise Levels

3.14 Single figure results can be seen in Appendix 2.

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d) Discussion

3.15 As can be seen from the table above, the existing residential properties are currently exposed to

high levels of incident noise. The temporary school building is currently exposed to moderate

levels of incident noise.

3.16 The LAeq,T levels were noted by the engineer attending site to be driven by vehicle noise in the

existing Tesco car park and traffic noise on Hazelwick Avenue. The LAF,max levels were noted to

be caused by passing vehicles and car door slams. It was noted that the LA90,T levels were

attributable to traffic along Hazelwick Avenue.

3.17 The lowest measured background (i.e. LA90,T) levels of 60.2 dB(A) and 49.2 dB(A) will be used in

the following assessment for residential properties on The Birches and the temporary school

building respectively.

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4 SPECIFIC NOISE – DUDLEY, CHELTENHAM & BRISTOL

a) Measurements

4.1 Attended measurements were carried out over the following time periods:

� Daytime at Dudley - between approximately 10:00 and 11:00 hours on 21st February 2012

� Daytime at Cheltenham – between approximately 10:00 and 10:00 hours on 13th June 2012

� Daytime at Bristol – between approximately 11:30 and 11:40 hours on 13th June 2012

4.2 The engineer attending site liaised with the operator of the car washing facility to ensure that

worst-case noise data was captured for a variety of activities associated with the facility.

4.3 Measurements were made at a variety of locations, in order that the noise impact of such

activities could be accurately modelled.

4.4 The measurement positions selected for the survey were varied and were intended to capture the

noise impact of the car washing operation in various different stages.

4.5 Noise measurements were made using a Class 1 Svan 949 & Svan 945a, generally in

accordance with BS EN 60651:1994 and BS 7445:1993.

4.6 The meter was calibrated before and after each survey and no significant drift was witnessed.

4.7 Copies of the relevant calibration certificates associated with the meter are available upon

request.

4.8 Local weather conditions for the Dudley site were generally dry and calm. The temperature

measured during the attended survey period was 8 °C. Wind speeds were < 5 m/s.

4.9 Local weather conditions for both the Cheltenham and Bristol sites were generally dry and calm.

The temperature measured during the attended survey periods was steady at 14 °C. Wind

speeds were < 5 m/s.

4.10 The time period, T, varied with the type of activity under measurement, but was generally LAeq,1min.

4.11 Measurements were made for the vacuum cleaner in an undercroft car park and can therefore be

considered to include reverberant noise build-up due to the semi-enclosed location. This

therefore represents a worst-case scenario situation.

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b) Results

4.12 Table 2 shows the results of the daytime survey. All measurements are in dB(A):

Operation Location LAeq,T

Dudley (22nd

February, 10:00 to 11:00hours)

Ambient level 1 m from facility 56.3

Vacuum 1 m from operation 59.3

Noise level at source – vacuum: 56.3

Cheltenham (13th

June, 10:00 to 10:30hours)

Ambient level 1 m from facility 55.6

Submersible water pump 1 m from operation 53.7

Noise level at source – pump: 0

Bristol (13th June, 11:30 to 12:00hours)

Ambient level 1 m from facility 57.9

Jet wash & compressor 1 m from operation 77.1

Noise level at source – jet wash & compressor: 77.1

Table 2 – Measured Specific Noise Levels

c) Discussion

4.13 As can be seen from the Table above, a car washing facility of the type proposed generates a

moderate level of noise.

4.14 As can be seen from the Table, the jet wash and compressor are by far the noisiest activities

associated with the car wash. The noise generation of the vacuum is shown to be consistently

less than 10 dB below the levels generated by the jet wash and compressor. Therefore, running

both the jet wash and vacuum simultaneously would result in no overall increase in noise level

over running the jet wash in isolation.

4.15 It is understood that the application includes for 2 jet wash / compressors which could potentially

be used simultaneously. Therefore, the ‘worst-case’ momentary noise level in any one hour

period would be 80.1 dB(A). To account for this potential eventuality, two ‘jet wash’ noise

sources (each at 77 dB(A)) have been included in the model. In order to cover all situations, two

‘vacuum’ noise sources have also been included.

4.16 It should be noted that BS 4142 suggests that the specific noise should be assessed over a 1

hour period. The following assessment is therefore based on a ‘worst-case’ momentary noise

level being constant for a 1 hour period. In reality, it is expected that the operation of the jet

washes and compressors will be active for much shorter, intermittent periods. The actual noise

impact, when assessed over 1 hour, may therefore be lower than as modelled in calculation.

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5 3D NOISE MODEL

5.1 A 3D computer model of the site has been created3, in order to asses the likely impact of locating

a car washing facility identical to that at the Tesco Bristol, Cheltenham and Dudley sites, at Tesco

Extra Crawley Hazelwick.

5.2 A 3D noise model is capable of accurately predicting noise propagation, by taking into account

variations in topography, barrier attenuation provided by existing landscaping and buildings, and

distance attenuation.

5.3 The location of the proposed car wash is as shown on proposed plans received from Gilmore

Consultancy Ltd. The location of the cabin and screens surrounding the car wash are taken from

elevation drawings provided by Gilmore.

5.4 As discussed in the Sections above, a ‘worst-case’ Specific noise level of 77.1 dB(A) has been

entered into the model as a point source for each jet wash / compressor, and verified using

survey data to calibrate the model. Specific noise levels of 56.3 dB(A) have been used for each

vacuum noise source. The locations of the noise sources have been taken from drawings (ref:

02424935) issued by Gilmore.

a) Car Wash Facility

5.5 The screenshot below, taken from the 3D computer noise model (shown in Appendix 3), shows

the location of the proposed car washing facility and associated noise sources (i.e. jet washes

and vacuum units).

Figure 1 – 3D Noise Model Showing Proposed Car Wash Facility & Noise Source Locations

3 Noise model created using Sound Plan software version 7.1

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b) Assessment Locations

5.6 The screenshot below, taken from the 3D computer noise model (shown in Appendix 3), shows

the proposed car wash facility and assessment locations for noise impact. These are taken as

the ground floor windows (i.e. 1.5m height) of the nearest residential properties on The Birches

and the temporary school building.

Figure 2 – 3D Noise Model Showing Proposed Car Wash Facility & Assessment Locations

c) Results

5.7 Table 3 shows calculated sound pressure levels due to the car washing activity for the

assessment locations shown above.

5.8 As discussed above, an absolute worst-case-scenario assessment has been conducted based on

the ‘worst-case’ Specific noise (i.e. both jet washes and compressors) being present for the

entirety of the 1 hour assessment period (i.e. operating 100% of the time) required under BS

4142. In addition, the impact of this worst-case scenario has been modelled during the quietest 5

minute period of a typical week, therefore representing the most robust assessment conditions

possible.

5.9 In order to provide a fuller and more realistic picture of anticipated daily noise impact (where the

operation of the jet washes will be intermittent), the following “on-time” scenarios have also been

modelled:

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� Each jet wash 50% on-time in a 1 hour period

� Vacuums 75% on-time in a 1 hour period

5.10 Table 3 shows the modelled noise impact. All levels are in dB(A):

Assessment Location Predicted Noise Impact dB(A)

100% Usage

Predicted Noise Impact dB(A)

Typical Usage

The Birches 42.9 39.9

Temporary School Building 28.6 26.0

Table 3 – Modelling Results

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6 BS 4142 CALCULATION

a) Calculations

6.1 Table 4 shows the calculated worst-case scenario noise impact due to the proposed car washing

facility (taken from the 3D computer noise model) and the measured levels of background noise

at existing residential receptors. All figures are in dB(A):

Assessment

Location

Specific

Noise

Level

dB(A)

Rating Level

with 5 dB

Tonality

Penalty dB(A)

Existing

Background

Noise dB(A)

Difference

dB

100% Usage

The Birches 42.9 47.9 60.2 -12.3

Temporary School Building

28.6 33.6 49.2 -15.6

Typical Usage

The Birches 40.0 45.0 60.2 -15.2

Temporary School Building

26.1 31.1 49.2 -18.1

Table 4 – BS 4142 procedure

b) Discussion

6.2 BS 4142 states that:

� if the Rating level is 10 dB or more above the measured background level then this is an

indication that complaints are likely.

� if the Rating level is around 5 dB above the background level, this is of marginal significance

� if the Rating level is 10 dB or more below the background level, this is a positive indication

that complaints are unlikely.

6.3 As can be seen from the Table above, the BS 4142 assessments at all locations are greater than

10 dB(A) below the existing lowest level of background noise. This therefore is “a positive

indication that complaints are unlikely”. The BS 4142 assessments also satisfy the requirements

set by Crawley Borough Council (i.e. ≥5dB below the background noise level).

6.4 It should be noted that the time period used in assessment is considerably shorter than that

permitted under BS 4142 (5 minutes versus 1 hour). The assessment above assumes the ‘worst-

case’ Specific noise (i.e. jet washes and compressors) would be present for 100% of the

measurement period. In reality, this situation would not occur and the Specific noise would

actually be intermittent and divided by periods of silence as a result of inactivity.

6.5 The predicted noise impact under any assessment condition therefore suggests that the

proposed car wash should have no negative effect on ambient noise levels at nearby residential

properties and the temporary school building.

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7 OUTDOOR AMENITY SPACES

7.1 Guidance given in BS 8233 and the WHO Guidelines for Community Noise states that it is

desirable for the steady noise level in external amenity areas (such as gardens or outdoor living

areas) to be less than 50 dB LAeq,T with 55 dB LAeq,T regarded as an upper limit.

7.2 Predicted values from the 3D noise model indicate that the maximum noise impact in external

amenity spaces due to the operation of the proposed car washing facility would be at worst 44

dB(A) for nearby residential properties and 46 dB(A) for the school.

7.3 It can therefore be seen that external amenity should not be negatively affected by the operation

of the car washing facility.

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8 CONCLUSIONS

8.1 Prevailing noise levels at a proposed car wash site have been recorded, and the lowest prevailing

background noise level has been identified.

8.2 Measurements have also been made of the Specific noise which is to be introduced into the area

(a car washing facility).

8.3 Results show that an assessment of ‘worst-case’ conditions under BS 4142 returns a metric

stating that the figures give “a positive indication that complaints are unlikely”.

8.4 Results also show that an assessment of ‘worst-case’ conditions under BS 4142 returns a metric

that satisfies the requirements set by Crawley Borough Council.

8.5 An assessment of outdoor amenity spaces has shown that the noise impact of the proposed car

washing facility would not result in a breach of BS 8233 / WHO criteria.

8.6 It is therefore considered that the operation of the car wash should have no negative impact on

amenity at nearby residential properties and the temporary school building, and that this impact

would be categorised as ‘NOEL’ under the National Planning Policy Framework document.

RPS Highfield House 5 Ridgeway Quinton Business Park Birmingham B32 1AF B7133/ENV/P1 4

th April 2013

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Key:

Measurement Position

Proposed Car Wash Location

Nearest Residential Properties

Temporary School Building

APPENDIX 1 – SITE PLAN SHOWING APPROXIMATE

MEASUREMENT POSITION

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APPENDIX 2 – MEASUREMENT RESULTS

a) Daytime survey results – 28th

March 2013

All measurements are in dB(A). The measurement period, T, was set to 5 minutes.

Measurement Position

Time (hh:mm)

Duration (mins)

LAeq,T (dB)

LAF,max

(dB) LA10,T

(dB) LA90,T

(dB)

1 10:02 5 54.1 74.6 56.0 49.2

1 10:07 5 59.9 86.7 58.8 51.1

1 10:12 5 52.3 68.2 53.6 49.7

1 10:17 5 52.6 66.1 54.1 50.3

1 10:22 5 54.8 69.1 56.8 50.5

1 10:27 5 54.6 65.4 56.3 51.8

2 10:35 5 70.7 78.3 74.2 61.6

2 10:40 5 70.6 79.6 73.9 62.6

2 10:45 5 71.7 82.5 74.7 64.3

2 10:50 5 70.7 79.4 74.6 60.2

2 10:55 5 71.1 84.6 74.4 60.6

2 10:59 5 71.1 79.4 74.5 62.1

1 11:06 5 57.4 75.3 58.1 51.2

1 11:11 5 56.5 74.0 58.6 52.1

1 11:16 5 55.3 69.4 58.2 51.1

1 11:21 5 65.9 96.9 59.5 51.5

1 11:26 5 54.0 65.8 55.8 51.0

1 11:31 5 56.3 74.6 55.9 51.8

2 11:39 5 72.5 82.3 75.6 66.3

2 11:44 5 72.4 85.6 75.4 62.8

2 11:49 5 71.8 80.4 75.1 64.0

2 11:54 5 72.7 81.0 75.7 66.0

2 11:59 5 70.3 75.3 73.0 62.0

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APPENDIX 3 – 3D NOISE MODEL