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10. Noise


10.1 Introduction
10.1.1      Noise can have an effect on the environment and on the quality of life enjoyed
            by individuals and communities. The impact of noise can therefore be a
            material consideration in the determination of planning applications.
10.1.2      This assessment will consider the impact of operational noise from the
            proposed substation upon the nearest, worst affected noise sensitive receptor
            location(s). Predicted operational noise levels from the substation have been
            compared with the existing baseline conditions to determine the significance of
            the noise impacts generated by permanent plant installations on site. The
            operational noise levels of the transformers are based upon maximum
            emission data supplied by the scheme engineers.
10.1.3      Potential noise impacts arising during the construction phase of the cable link
            and substation were considered as part of the assessment. The noise
            contributions of all mobile and fixed plant working on the development of the
            substation itself, and upon the construction of the onshore cable link between
            the substation and the mean low water mark, have been predicted and
            assessed with respect to the relevant guidance. Details of the construction
            methodology have been taken from the construction methodology prepared by
            PB Power (PB. Power, 2006) and summarised in Section 5.
10.1.4      The construction methodology states that vehicle movements associated with
            the development are limited in number, thus no assessment of traffic noise is
            presented, as for a 1dB change in traffic noise, a change in traffic levels of
            25% would be necessary.


10.2 Methodology

Noise Terminology
10.2.1      The ratio between the quietest audible sound and the loudest tolerable sound
            is a million to one in terms of the change in sound pressure. Because of the
            wide range a scale based on a logarithmic basis is used in noise level
            measurement. The scale used is the decibel (dB) scale which extends from 0
            to 140 decibels (dB) corresponding to the intensity of the sound pressure
            level. The ear has the ability to recognise a particular sound depending on the
            pitch or frequencies found at the source. Microphones cannot differentiate
            noise in the same way as the ear; and to counter this weakness the
            noise-measuring instrument applies a correction to correspond more closely to
            the frequency response of the ear. The correction factor is called “A
            Weighting” and the resulting measurements are written as dB(A). “A


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            Weighting” refers to the noise level that represents the human ear’s response
            to sound. The dB(A) is internationally accepted and has been found to
            correspond well with people’s subjective reaction to noise. Typical dB(A)
            noise levels for familiar noises are given in Table 10.1.


Table 10.1       Typical Noise Levels


Approximate Noise Level dB(A)                       Example

0                                                   Limit of hearing

30                                                  Rural area at night, no wind or adverse weather conditions

40                                                  Library

50                                                  Quiet office without noisy machinery, such as typewriters

60                                                  Normal conversation

70                                                  In car noise without radio

80                                                  Household vacuum cleaner

100                                                 Pneumatic drill

140                                                 Threshold of pain

Source: Entec.



10.2.2      The noise levels given in Table 10.1 are sound pressure levels (SPL) and
            describe the noise level at a point in space. Sound power levels (SWL) are
            used to describe the noise output of a noise source. Noise levels vary over
            time depending on noise generating activities. The following indices are used
            to take account of these variations:
            • LAeq T is the equivalent continuous sound level and is the sound level of a
              steady sound having the same energy as a fluctuating sound over the
              same period (T). It is possible to consider this level as the ambient noise
              encompassing all noise at a given time. LAeq T is considered the best
              general purpose index for environmental noise;
            • LA90 T index represents the noise level exceeded for 90 percent of the
              measurement period and is used to indicate quieter times during the
              measurement period. It is usually referred to as the background noise
              level;
            • LA10 T refers to the level exceeded for 10% of the measurement period
              respectively. LA10 T is widely used as a descriptor of traffic noise; and
            • LAmax is maximum recorded noise level during the measurement period.




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Guidance Documents
10.2.3      British Standard 4142:1997 ‘Method for Rating Industrial Noise affecting mixed
            Residential and Industrial Areas’ contains guidance on the assessment of
            industrial noise, and the prediction of the likelihood of complaints from
            residents affected by such sources. The methodology compares industrial
            noise levels at the noise sensitive receptors with existing background noise
            levels.
10.2.4      British Standard 5228 - Part 1:1997 ‘Noise and Vibration Control on
            Construction and Open Sites’ contains guidance on the prediction of noise
            levels at sensitive receptors from the operation of fixed and mobile noise
            sources found on construction and other open sites.
10.2.5      The Department of the Environment (DoE) Advisory Leaflet (AL) 72 gives
            guidance on appropriate noise levels from construction sites.

Baseline Noise Monitoring
10.2.6      Background noise level monitoring was undertaken in the vicinity of the
            substation on 8th August 2007. The purpose of the monitoring was to
            determine the existing noise climate at the nearest noise sensitive receptor to
            the substation.     The nearest receptor is located at Warrenby House,
            southwest of the site boundary.
10.2.7      Due to access restrictions, it was not possible to monitor directly at the façade
            of Warrenby House. Therefore, noise levels were recorded at a position
            equidistant from Tod Point Road, close to the property.
10.2.8      Noise levels were recording continuously in consecutive 5-minute periods,
            from 0135hrs to 0305hrs for a total period of 1.5hrs.
10.2.9      The monitoring was undertaken in accordance with the methodology outlined
            in BS 7445-1:2003 ‘Description and Measurement of Environmental Noise’.
            The meter was positioned at 1.2 m above local ground level and positioned
            away from any reflective facades. The measurements were undertaken using
            a Rion NL-31 Class 1 integrating sound level meter. Calibration and battery
            levels were checked before and after the monitoring. No significant drift in
            calibration was recorded.
10.2.10 The weather conditions during the survey were dry and clear, with a light
        breeze. Average wind speeds were below 5 m/s during the survey. The
        temperature was in the range 15-18ºC

Assessment Methodology – Construction Noise
10.2.11 Construction noise generated during the development phase is assessed
        using the methodology of BS5228-Part 1:1997 ‘Noise and Vibration Control on
        Construction and Open Sites’ which contains guidance on the prediction of
        noise levels at sensitive receptors from the operation of fixed and mobile noise
        sources found on construction and other open sites.



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10.2.12 The noise modelling process is complex, but in simple terms it involves the
        input of the following source data.
            • Noise emission data taken from a recent Defra Report ‘Update of Noise
              Database for Prediction of Noise on Construction and Open Sites’ (2005),
              or from BS5228, is assigned to each item of plant.
            • Distance between noise source and receptor.
            • Ground attenuation - related to the ground cover between the source and
              the receptor.
            • Barrier attenuation - related to any barriers between the source and the
              receptor.
            • On-time of plant - construction operations commonly involve the intermittent
              use of various items of plant, determined by the construction programme,
              and the specific task being undertaken.
            • Mobile plant - an allowance is made for mobile plant which moves around
              the site, and will be at differing distances from the receptor.
10.2.13 The Department of the Environment (DoE) Advisory Leaflet (AL) 72 gives
        guidance on appropriate noise levels from construction sites. The leaflet
        states that the noise level outside the nearest occupied room should not
        exceed:
            • 75 dB(A) in urban areas near to main roads in heavy industrial areas; or
            • 70 dB(A) in rural, suburban and urban areas away from main road traffic
              and industrial noise.
10.2.14 Two receptors considered in the assessment of construction noise, namely
        Warrenby House, a short distance from the substation, and Marsh Farm
        House, the closest receptor to the cable route.

Assessment Methodology – Operational Noise
10.2.15 Operational noise from the site has been assessed in accordance with British
        Standard 4142:1997 ‘Method for Rating industrial noise affecting mixed
        residential and industrial areas’ which contains relevant guidance on the
        assessment of industrial noise and the likelihood of complaints from residents
        affected by such sources.
10.2.16 The methodology compares industrial noise levels at the noise sensitive
        receptors with existing background noise levels. A difference of +10dB or
        more between the existing background level and the industrial noise source
        indicates that complaints are likely, whereas +5dB is of marginal significance.
        For differences of less than +5dB, the likelihood of complaints reduces further.
10.2.17 Once commissioned, the substation will operate continuously over 24 hours
        per day. As ambient noise levels are likely to be at their lowest during the



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            night-time, it is at this time that there is the greatest potential for noise from the
            installation to give rise to disturbance. If it can be demonstrated that noise
            from the substation does not give rise to disturbance during the night-time, it
            can be concluded that noise in the daytime will also not cause disturbance,
            when ambient noise levels are higher
10.2.18 An operational noise level was predicted for the closest receptor using Lima,
        an industry standard computational noise model. The software takes account
        of the relative positions of the noise sources and receiver points and
        calculates the resulting noise level at the receiver points based on the
        source/receiver distance, ground and barrier attenuation and reflections from
        other surfaces. Given the open nature of the site and transformer pens, noise
        levels were predicted using the same BS5228 Part 1:1997 modelling
        methodology used for the construction noise calculations.
10.2.19 As the closest property to the proposed substation, only the Warrenby House
        receptor is considered for operational substation noise.
10.2.20 It is understood that there are no other schemes in the immediate vicinity of
        the works with the potential to influence noise levels to a degree that would
        alter the conclusions of this assessment; hence cumulative effects are not
        considered.


10.3 Baseline
10.3.1      Baseline noise levels at Warrenby House, the nearest noise sensitive receptor
            to the substation site were monitored in accordance with the methodology
            described above. The results of the monitoring are detailed in Table 10.2.

Table 10.2      Noise Monitoring Results


Time                                           LAeq (dB)            LAmax (dB)            LA10 (dB)    LA90 (dB)


08/08/2007 01:34                                  47.9                 59.7                     49.4      46.0

08/08/2007 01:39                                  48.6                 57.9                     50.1      46.8

08/08/2007 01:44                                  48.0                 55.2                     49.6      45.9

08/08/2007 01:49                                  47.0                 54.8                     47.9      45.8

08/08/2007 01:54                                  49.0                 62.6                     51.9      45.3

08/08/2007 01:59                                  46.3                 55.0                     47.3      44.6

08/08/2007 02:04                                  47.2                 50.7                     48.2      46.3

08/08/2007 02:09                                  48.5                 55.3                     50.4      46.2

08/08/2007 02:14                                  48.6                 63.9                     48.9      45.9

08/08/2007 02:19                                  47.9                 61.6                     48.2      45.4




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Time                                           LAeq (dB)            LAmax (dB)            LA10 (dB)    LA90 (dB)


08/08/2007 02:24                                  46.6                 54.9                     47.6      45.3

08/08/2007 02:29                                  46.5                 49.9                     47.6      44.9

08/08/2007 02:34                                  46.3                 53.5                     47.7      44.7

08/08/2007 02:39                                  47.9                 57.6                     49.7      45.8

08/08/2007 02:44                                  45.2                 52.4                     46.2      44.1

08/08/2007 02:49                                  45.9                 50.6                     47.2      44.5

08/08/2007 02:54                                  45.7                 50.4                     47.1      44.2

08/08/2007 02:59                                  46.0                 56.9                     46.2      44.3

                            AVERAGE               47.3                                          48.4      45.3


10.3.2      It was observed that the existing noise climate at the monitoring location was
            dominated by continuous industrial noise from the Corus Steelworks, located
            to the west of the site at a distance of approximately 1.2km. No other noise
            sources of significance were noted during the survey.
10.3.3      Traffic on Tod Point Road, to the south of the measurement location, was
            limited to a single car during the whole 1.5hr monitoring period, and hence did
            not have a significant effect on the noise levels recorded.


10.4 Information Gaps
10.4.1      The source noise levels from the operational transformers are not known.
            However, the scheme engineers, PB. Power Ltd., have stated that the
            guidance document to which the substation will be designed requires that
            noise levels from the two transformers are no greater than 79dB at 2m. This
            document specifies a maximum permissible noise emission from any
            transformer. The noise output of the transformers will vary according to the
            output of Teesside Offshore Wind Farm and the maximum may be lower than
            the specified level; however to present the realistic worst case noise modelling
            was carried out using the quoted maximum noise level of 79dB at 2m
            distance. The proposals also include for the installation of gas insulated
            switchgear, housed within a fully enclosed building. It is understood that this
            equipment will be designed to comply with the Control of Noise at Work
            Regulations (2005), thus a noise level of 85dB at 1m has been assumed.




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10.5 Mitigation, Offsetting and Enhancement Measures
     Incorporated into the Proposed Development
Industrial Noise
10.5.1      The design of the substation has considered the noise output from the
            substation to ensure that emissions do not result in unacceptable levels at the
            nearest receptor.

Construction Noise
10.5.2      Construction works, such as those which will be involved in the development
            of the substation and cable link, are often characterised by temporary
            increases in ambient noise levels which may result in short-term disturbances
            to nearby sensitive receptors.
10.5.3      Good practice measures will be used to manage construction noise.
            Examples of such measures are listed below.
            • Use of equipment fitted with effective silencers/insulation.
            • Use of SMART reversing alarms to reduce the effect of reversing bleepers
              on site vehicles.
            • All plant to be regularly serviced, maintained and operated in accordance
              with manufacturer’s instructions. Machines that are intermittently used
              would be shut down in the intervening periods between work or throttled
              down to a minimum.
            • All items of continuously operating semi-permanent equipment i.e.
              generators, compressors, cement mixers etc. to be kept towards the
              northern end of the site, to reduce noise levels to nearby residential
              receptors. All of these items should be kept at a minimum distance of 60m
              from Warrenby House.
            • Appointment of site contact to whom complaints/queries about construction
              activity can be directed. Any complaints to be investigated and action
              taken where appropriate.
            • All construction activity to be undertaken in accordance with good practice
              as described by BS 5228.

            • The site will register with the Considerate Constructors Scheme, which is a
              Government endorsed scheme which encourages good practice on
              construction sites. Registered sites provide a commitment to comply with a
              Code of Practice which details how the construction site should present
              itself to and interact with the general public. In addition to guidance on
              cleanliness, safety, responsibility and environmental issues, a specific
              commitment to keep noise from construction operations to a minimum at all
              times is included in the Code of Practice. Membership of this scheme (or a




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                similar scheme) will ensure that any noise effects during the construction
                phase will be effectively managed.
              • Noisy construction activities will normally be restricted to 0730 to 1900hrs in
                the summertime, and 0730 to 1700hrs in the winter, Monday to Friday,
                0730 to 1200hrs on a Saturday.
Table 10.3      Mitigation, Offsetting and Enhancement Measures Summary


Impact                            Incorporated                             Extent to which impact     Monitoring
                       mitigation/offsetting/enhancement                      mitigated/offset/      requirements
                                    measures                                     enhanced               (if any)

Construction    Use of equipment fitted with effective                     Substantially             None
noise           silencers/insulation.

                Use of SMART reversing alarms to reduce the effect
                of reversing bleepers on site vehicles.

                All plant to be regularly serviced, maintained and
                operated in accordance with manufacturer’s
                instructions. Machines that are intermittently used
                would be shut down in the intervening periods
                between work or throttled down to a minimum.

                All items of continuously operating semi-permanent
                equipment i.e. generators, compressors, cement
                mixers etc. to be kept towards the northern end of
                the site, to reduce noise levels to nearby receptors.
                All of these items should be kept at a minimum
                distance of 60m from Warrenby House.



                Appointment of site contact to whom
                complaints/queries about construction activity can
                be directed. Any complaints to be investigated and
                action taken where appropriate.

                All construction activity to be undertaken in
                accordance with good practice as described by
                BS 5228.

                The site will register with the Considerate
                Constructors Scheme, which is a Government
                endorsed scheme which encourages good practice
                on construction sites. Registered sites provide a
                commitment to comply with a Code of Practice
                which details how the construction site should
                present itself to and interact with the general public.
                In addition to guidance on cleanliness, safety,
                responsibility and environmental issues, a specific
                commitment to keep noise from construction
                operations to a minimum at all times is included in
                the Code of Practice. Membership of this scheme
                (or a similar scheme) will ensure that any noise
                effects during the construction phase will be
                effectively managed.

                Noisy construction activities will normally be
                restricted to 0730 to 1900hrs in the summertime,
                and 0730 to 1700hrs in the winter, Monday to
                Friday, 0730 to 1200hrs on a Saturday.

Operational     None                                                       None                      None
Noise




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10.6 Predicted Impacts and Effects

Construction Noise Levels
10.6.1        The Construction Method Statement (produced by PB Power) states that the
              following operations will be included in the construction phase of the
              development:
              • substation construction – creation of foundations for buildings, construction
                of buildings and enclosures, installation of infrastructure and services etc;
                and
              • onshore cabling – installation of onshore HV cable link between the
                Interface Joining Pit (IJP) and the substation.
10.6.2        Onshore cabling operations are further divided between installation of the link
              from the IJP to a point located adjacent to the Corus Steelworks (by means of
              directional drilling) and installation of the link between Corus Steelworks and
              the substation (by means of conventional trenching).
10.6.3        For substation construction, there will be a short phase of foundation
              construction (4 weeks), followed by the construction of the substation itself (11
              months). Both situations are considered separately in the assessment. It is
              further indicated in the construction method statement that construction of the
              foundations is likely to be based upon concrete pads only, but that short piles
              may also be used if considered necessary. Noise levels are therefore
              calculated for piling and pad construction, and for pad construction operations
              only during this phase.
10.6.4        Predicted noise levels due to the above operations have been calculated
              using typical plant equipment configurations for each phase of activity (based
              on Entec’s experience of similar operations on other projects). Full details of
              the plant equipment used in the noise level predictions for construction of the
              substation are shown in Table 10.4. For cabling operations, the plant
              equipment used is shown is Table 10.5.

Table 10.4       Noise Emission Data for Construction Plant (Substation)


Plant                                                                    % On Time              Sound Power Level (dB)

General Construction

Compressor                                                                     83                        103

Generator                                                                      83                        105

Concrete Mixer                                                                 83                        105

Scaffolding                                                                    83                        100

Block work erection                                                            83                         75

Road lorry delivering material                                                 83                        108




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Plant                                                                    % On Time              Sound Power Level (dB)

Excavator                                                                      83                        104

Site Dumper                                                                    83                        106

Site Forklift                                                                  83                        104



Piling Operations

Piling Rig – Precast Concrete Piles (Drophammer)                               60                        116

Excavator                                                                      83                        104



Construction of Concrete Pads

Lorry mounted mixer – discharging                                              83                        109

Vibrating poker                                                                83                        102

Concrete Scabbler                                                              83                        111

Knocking out shuttering                                                        83                        107

Table 10.5        Noise Emission Data for HV Cabling Operations


Plant                                                                    % On Time              Sound Power Level (dB)

Directional Drilling

Hansherr HL8 Drilling Rig                                                     100                        118

Compressor                                                                    100                        100



Conventional Trenching

CAT 322 excavating                                                             83                        104

Road Lorry importing fill                                                      83                        108

CAT 322 handling pipe/filling trench                                           83                        104

Wheeled tamper                                                                 83                        106

Site Dumper                                                                    83                        106

Samsung 350 Pecker                                                             83                        116



10.6.5          Noise levels are calculated at the location of the nearest, worst affected noise
                sensitive receptors as follows:
                • Warrenby House
                • Marsh Farm House




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10.6.6      Where uncertainties exist which could affect the outcome of the noise
            predictions, ‘worst-case’ assumptions have been used. Consequently the
            predicted noise levels will be over-estimates. Examples of ‘worst-case’
            assumptions include:
            •    Plant location - all plant is assumed to be at the closest approach to the
                receptor where appropriate.
            •     ‘On-time’ of plant - experience has shown that even when plant items are
                highly used, the maximum ‘on-time’ is less than around 83%, due to the
                ‘down time’ associated with plant breakdowns, maintenance and routine
                servicing. Furthermore a piece of mobile plant will only emit 100% noise
                power at specific parts of its work cycle e.g. excavators digging into the
                ground rather than tipping the excavated material. This assessment has
                therefore been prepared on the basis that all mobile plant will operate at
                maximum efficiency (i.e. 83%). Some items of fixed plant, such as
                generators, have been assumed to have a 100% on-time. Other items of
                plant which are used infrequently at maximum power have other
                appropriate on-times assigned to them.
            •    Ground attenuation - the nature of the ground intervening between source
                and receptor is variable. An assumption of 100% ‘acoustically hard’ ground
                between the receptors and the source has been made.
            •    Weather - The BS 5228 methodology assumes that the receptor is
                downwind of the noise source, which is when the highest noise levels will
                be experienced. During periods when the wind is blowing in a different
                direction, noise levels could be 2-3 dB(A) lower than those predicted.
10.6.7      The predicted noise levels due to construction activities are shown in Table
            10.6.

Table 10.6      Predicted Noise Levels for Construction Operations


Activity                                                 1. Warrenby House                      2. Marsh Farm House

General Construction (substation)                                  69.3                                48.2

Piling Operations (substation)                                     71.6                                49.1

Construction of Concrete Pads (substation)                         71.0                                48.5

Directional Drilling (HV cabling)                                  40.6                                44.5

Conventional Trenching (HV cabling)                                53.9                                54.8



Total Noise (Pilling and concrete pad                              74.3                                56.8
construction)

Total Noise (Concrete pad construction                             71.1                                55.7
only at substation)

Total Noise (General construction at                               69.5                                56.0
substation)




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10.6.8      The above noise levels are assessed with respect to the guidance of DoE
            Advisory Leaflet 72. Since the site is located in a predominantly urban area
            close to heavy industry and road traffic, lower noise limit of 75dB(A) is
            appropriate.
10.6.9      Table 10.6 shows that all construction activities comply with the 75dB(A) noise
            limit at both receptors.
10.6.10 No assessment of construction traffic noise has been carried out as the
        forecast number of HGV movements (up to 14 HGV movements per day for
        the most intensive period of construction) is not considered likely to result in a
        significant noise effect for the access road to the substation.

Operational Noise Levels
10.6.11 Operational noise levels have been predicted using the BS5228 methodology
        outlined above.      The gas insulated switchgear and both transformers
        operating at the maximum noise output results in a predicted noise level of
        41.8dB LAeq at the façade of the nearest receptor. It is not known at this time
        whether the transformer sources would attract a rating penalty for tonality or
        impulsivity as outlined in BS4142. However, some transformers do exhibit low
        frequency tonal components, thus in order to present the worst case scenario,
        a 5dB rating penalty has been added to the noise levels at the receptor, when
        performing the BS4142 assessment.
10.6.12 The BS4142 assessment and results are presented in Table 10.7.


Table 10.7      Night-Time BS4142 Assessment


                                                                            Noise Level

                                                                                  41.8
Predicted Plant Noise level dB LAeq,1h

Rating Penalty dB                                                                 +5

Rating Level dB(A)                                                                46.8

Average Night-time LA90, 5mins                                                    45.3

Difference dB(A)                                                                 +1.5

Likelihood of complaint                                                   Less than marginal



10.6.13 The assessment has shown that, in accordance with BS4142 methodology,
        the likelihood of complaints at the nearest receptor is less than marginal.
10.6.14 There is potential for additional noise emission from the air-blast circuit
        breakers associated with the gas insulated switchgear. These are very short
        term events of less than one second in duration, which would occur no more
        than twice annually. The noise levels from such an event would be in the
        region of 77dB at the Warrenby House receptor. Whilst this would result in


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            levels 30dB greater than the existing ambient noise level, the circuit breakers
            are necessary for the safe operation of the switchgear and as the events
            would occur infrequently are not considered to cause excessive disturbance at
            the receptor.


10.7 Evaluation of Effects

Criteria for Evaluation
10.7.1      The determination of significance has largely been based upon the relevant
            assessment criteria for the specific noise issue being assessed, e.g. BS4142
            criteria for industrial noise, AL72 criteria for construction noise. These
            assessment criteria are not directly related to the categories of ‘Significant’
            and ‘Not significant’ that underpin EIA. The determination of significance in
            EIA is based on the sensitivity of a particular receptor (which depends on local
            circumstances), as well as the magnitude of change in noise levels (which is
            related to existing background noise levels and predicted noise levels due to
            the development) and whether it exceeds or complies with relevant guideline
            noise limits, irrespective of the amount of change predicted.

Construction Noise
10.7.2 For each phase of the construction programme, the determination of impact
       significance is based upon compliance with the applicable noise limit; i.e.
       breach of the noise limits indicates a ‘significant’ effect, whereas compliance
       with noise limits indicates a ‘not significant’ effect.
10.7.3      As outlined in Section 10.2, the noise limits proposed herein are based upon
            AL(72) criteria for construction noise in an urban area. The predicted noise
            levels for each phase have been compared with the construction noise limit in
            Section 10.6, above.

Operational Noise
10.7.4 The determination of impact significance in relation to operational noise is
        based upon the magnitude of the substation noise levels over the measured
        background at the receptors.
10.7.5      It was agreed with the Environmental Protection Section of Redcar and
            Cleveland Borough Council that applying BS4142 to the scheme would be an
            acceptable method of assessment for noise from the substation development,
            with the requirement that the likelihood of complaint would be less than
            marginal significance (i.e. background +5dB is regarded as the limit of
            acceptability for industrial noise at the nearest receptor).
10.7.6      Consequently, the guidance presented in BS4142 has been applied to noise
            levels from the development in Section 10.6, with resulting significance criteria
            as follows:
            • Complaints likely (difference of +10dB) - significant



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            • Marginal significance (difference of +5dB) - significant
            • Less than marginal significance (difference of less than +5db) - not
              significant
            • Complaints unlikely (difference of -10dB) - not significant

Summary Evaluation Table
10.7.7      A summary of the predicted noise effects is presented in Table 10.8. It is
            predicted that noise levels from both the construction of the development will
            be audible at Marsh Farm House (relating to the cable route) and Warrenby
            House (substation). It is also predicted that at times the operation of the
            substation will generate noise audible at Warrenby House, the nearest
            residential receptor, but that noise levels will vary in relation to the operational
            capacity of the site. All predicted noise levels comply with the applicable noise
            limits for construction and operational noise.


Table 10.8      Summary of Noise Effects


Effect                           Type of        Probability of          Significance of residual effect
                                 Effect         Effect Occurring
                                                                        Level          Rationale

Construction noise effects       Negative       Likely                  Not            Noise levels comply with AL(72)
upon nearby residential                                                 significant    criteria
receptor

Industrial noise effects upon    Negative       Likely                  Not            BS4142 assessment indicates
nearest residential receptor                                            significant    complaints are of less than marginal
                                                                                       significance




10.8 Monitoring
10.8.1      No formal monitoring programme for the site is proposed.


10.9 Summary of Key Findings and Conclusions
Construction Noise
10.9.1      An assessment of construction noise was undertaken by predicting noise
            levels from the development using the methodology of BS5228-1:1997 Noise
            and Vibration Control on Construction and Open Sites. Noise predictions
            were undertaken for piling, concrete pad construction, cable trenching and
            drilling in addition to general construction operations, for both Warrenby
            House and Marsh Farm House. At both locations predicted construction noise
            levels are below the limits recommended in the Department of the



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            Environment leaflet AL(72) Noise Control on Building Sites. Consequently, no
            significant effects are anticipated in relation to construction noise.

Operation Noise
10.9.2      The operational noise survey comprised the following elements:
            • initial site visit to scope assessment and select receptors;
            • noise survey to measure existing background levels at the selected
              receptor (Warrenby House) during the night-time;
            • prediction of noise emissions from the proposed substation; and
            • assessment of noise levels at Warrenby House in accordance with BS4142
              to determine acceptability.
10.9.3      The noise emissions of the transformers will vary with the output of the
            windfarm. However, to present a worst-case scenario, noise predictions were
            based upon the maximum noise level permitted within the engineering design
            specification.
10.9.4      It is not known at this time whether the transformer noise would contain any
            tonal or other distinguishing characteristics. However, to continue the worst-
            case assessment, a rating penalty of 5dB was added to the predicted noise
            levels to account for any such characteristics.
10.9.5      The BS4142:1997 assessment found that the likelihood of complaints from the
            site was less than marginal. Thus, the assessment concludes no significant
            effects in relation to operational noise.

10.10 References
British Standard 4142:1997 Method for Rating Industrial Noise affecting mixed
Residential and Industrial Areas
British Standard 5228-1:1997 Noise and Vibration Control on Construction and Open
Sites
British Standard 7445-1:2003 Description and Measurement of Environmental Noise
DEFRA (2005) Update of Noise Database for Prediction of Noise on Construction and
Open Sites
Department of the Environment (DoE) Advisory Leaflet (AL) 72
PB Power (2006) Construction Method Statement




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