NOISE ASSESSMENT REPORT SECTION 36C VARIATION … · figure 2-1: site location of damhead creek ccgt 1 & 2 power stations The proposed development is the construction and operation

NOISE ASSESSMENT REPORT SECTION 36C VARIATION DAMHEAD CREEK 2 POWER STATION

Name Job Title Signature Date

Prepared Georgia Zepidou Senior Consultant

AECOM

4 February

2016

Checked Eddie Robinson Principal Consultant

AECOM 4 February

2016

Technical Review

Yuyou Liu Associate

AECOM

4 February

2016

AMENDMENT RECORD

Issue Date Issued Date Effective Purpose of Issue and Description of Amendment

0 20 January 2016 20 January 2016 Draft for Comment

1 27 January 2016 27 January 2016 Revised draft

2 4 February 2016 4 February 2016 Final for Submission

TABLE OF CONTENTS

1. Introduction ............................................................................................................. 5

2. Description of the Proposed Development ............................................................. 6

3. Noise Criteria/Guidance .......................................................................................... 7

3.1 Overarching National Policy Statement for Energy (EN-1) ................................................................ 7

3.2 National Policy Statement for Fossil Fuel Electricity Generating Infrastructure (EN-2) ..................... 8

3.3 National Planning Policy Framework (NPPF) ..................................................................................... 8

3.4 Noise Policy Statements for England (NPSE) .................................................................................... 9

3.5 Environment Agency – Horizontal Guidance Note H1 ....................................................................... 9

3.6 Environment Agency – Horizontal Guidance for Noise Part 2 – ‘Noise Assessment and Control’

IPPC H3 ............................................................................................................................................ 10

3.7 Environment Agency – Noise Impact Assessment – information requirements .............................. 10

3.8 Damhead Creek 2 Power Station – Revised Noise Limits and Noise Monitoring & Management

Plan (NMMP) .................................................................................................................................... 10

4. Damhead Creek 2 Noise Assessment .................................................................. 11

4.1 Damhead Creek 2 Proposed CCGT Plant Equipment ..................................................................... 11

4.2 Noise Sensitive Receptors ............................................................................................................... 11

4.3 Potential Noise Control Measures .................................................................................................... 15

4.4 Noise Modelling ................................................................................................................................ 15

4.5 Noise Impact Assessment on Receptor Monitoring Locations ......................................................... 17

4.6 Noise Impact Assessment on Designated Nature Conservation Sites ............................................ 17

5. Conclusions .......................................................................................................... 19

Figures: Figure 2-1: Site Location of Damhead Creek CCGT 1 & 2 Power Stations

Figure 4-1: NMMP Monitoring Locations (taken from the NMMP)

Tables: Table 4-1: NMMP Revised Damhead Creek Noise Limit Levels

Table 4-2: Damhead Creek 2 Noise Limit Levels

Table 4-3: Damhead Creek 2 Nature Conservation Sites

DHC2 Noise Assessment Report – Section 36C Variation 4-Feb-16

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Table 4-4: Damhead Creek 2 Plant Sound Power Levels

Table 4-5: Summary of Prediction Results at Noise Sensitive Receptors from the Operation of DHC2

only

Annexes: Annex A: Glossary of Terms

Annex B: Proposed Site Layout

Annex C: Environment Agency – Nature and Heritage Conservation Site Maps

Annex D: Noise Contours

Annex E: Noise Contours – Habitat Sites


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1. Introduction AECOM has undertaken a Noise Assessment for the proposed Variation under Section 36(c) of the Electricity Act 1989 to the Damhead Creek 2 (DHC2) power station (hereafter referred to as the Proposed Development).

On 25 January 2011, ScottishPower secured consent under Section 36 of the Electricity Act 1989, for the development, construction and operation of a new 1,000 MW Combined Cycle Gas Turbine (CCGT) adjacent to the existing Damhead Creek Power Station. Further to this, on 28 July 2014 ScottishPower secured consent under Section 36(c) of the Electricity Act 1989 to increase the output of Damhead Creek 2 CCGT to 1,200 MW (DECC Reference 12.04.09.04/265C) and subsequently in October 2015 this was further increased to 1,800 MW output CCGT. ScottishPower now seek to further vary the existing consent to allow flexibility in the make-up of the plant to include up to 300 MW of Open Cycle Gas Turbine (OCGT) peaking plant, whilst retaining the previous 1800MW CCGT plant option. The Proposed Development therefore now comprises of either a CCGT or a CCGT/OCGT power station with a total combined electrical capacity up to 1,800 MW (ISO), hereafter referred to as the 1,800 MW CCGT with peaking plant scheme option. It is noted that the application to vary the consent retains the option of constructing the already consented 1,800 MW (ISO) CCGT only scheme option but also includes a new variation of up to 300 MW OCGT as part of the overall 1,800 MW (ISO) electrical output – this assessment therefore focuses on the new variant, as the already consented CCGT only option was fully assessed as part of the 2015 variation.

To support the application for a variation to the existing Section 36 consent, ScottishPower has undertaken this noise impact assessment to assess whether the change in noise levels as a result of implementing the 1,800 MW CCGT with peaking plant scheme option are likely to give rise to a significant effect and therefore what, if any, mitigation measures are required. The assessment is supplemented by a noise modelling study predicting the impact of the proposed power station on identified nearby noise sensitive receptors. The techniques used to minimise or control noise emissions from the proposed power station are identified and reviewed to determine whether any residual effects are likely to occur.

The currently consented 1,800 MW CCGT only scheme option was fully appraised for environmental impacts in the Environmental Information Report submitted to support that variation application in 2015. Whilst the 1,800 MW CCGT only scheme option is to be retained within the Section 36 consent, this assessment focuses on the new variant that ScottishPower is applying to have included within the Section 36 consent, that of 1,800 MW CCGT with up to 300MW peaking plant.

A glossary of noise terms is provided in Annex A for reference.


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2. Description of the Proposed Development

The Damhead Creek site is situated on the southern edge of the tongue of land, known as the Hoo Peninsula, located between the Thames and Medway estuaries in Kent. The proposed new power station will be to the east of the existing Damhead Creek CCGT Power Station site (DHC1) (see Figure 2-1 for the site location).

FIGURE 2-1: SITE LOCATION OF DAMHEAD CREEK CCGT 1 & 2 POWER STATIONS

The proposed development is the construction and operation of a gas fired power station with a total electrical output capacity of up to 1,800 MW adjacent to the existing Damhead Creek CCGT Power Station site. The plant would be fired on natural gas from the UK National Transmission network; no back-up firing on distillate fuel is proposed. As with the existing Damhead Creek CCGT, the plant will be air cooled. The power station will comprise a CCGT plant and potentially an OCGT peaking plant located on the same Site; the peaking plant would have an electrical output capacity of up to 300 MW but the combined electrical output from the CCGT and OCGT will not exceed the 1,800 MW capacity.

The plant will occasionally be shut down for brief periods of essential maintenance and statutory inspections. DHC2 is expected to have an annual availability of the order of 93% with the remainder of the time dedicated to annual maintenance or as a result of unplanned plant failures. The operational life time of the development will be of the order of 35 years. It is envisaged that the peaking plant will operate for up to 1,500 hours per year, to respond to peak demand on the UK transmission system. The CCGT units are expected to run at higher load factors in the early years of operation – of around 80%, then dropping off as more renewable energy is connected to the network.

The previously consented 1,800 MW CCGT only scheme comprised either a single shaft or a multi-shaft combined cycle arrangement with up to three gas turbines, each with a HRSG, and connected to either a dedicated steam turbine or a single steam turbine respectively, depending on the plant configuration.

The revised General Arrangement Plan (2016) (Annex B) is based on the arrangement of the multi shaft CCGT configuration and up to two peaking plant units. The CCGT configuration options above will be retained.

Details of the plant make-up, as assumed in the noise modelling are provided in Section 4.1.


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3. Noise Criteria/Guidance This noise assessment has been undertaken with reference to appropriate regulatory guidance as outlined in this section. The assessment will be used to support both the Section 36 variation and any subsequent application for a variation to the Environmental Permit for DHC2; therefore the assessment follows guidance applicable to both regimes.

Whilst this scheme falls under the consenting scheme under the Electricity Act 1989, new applications for similar plant would fall under Section 15(2)(c) of the Planning Act 2008[1] and would therefore be a ‘nationally significant infrastructure project’ (NSIP). Under Section 104(3) of the Planning Act 2008, Development Consent Order (DCO) applications for NSIPs are required to be determined by the Secretary of State in accordance with policy set out in the relevant National Policy Statements (NPS), and it is considered that reference to the NPS is still relevant here even though this variation is applied for under the Electricity Act 1989.

3.1 Overarching National Policy Statement for Energy (EN-1) The Overarching National Policy Statement (NPS) for Energy (EN-1) sets out national policy for energy. The NPS states

“Where noise impacts are likely to arise from a proposed development, the applicant should include the following in the noise assessment:

• a description of the noise generating aspects of the development proposal leading to noise impacts, including the identification of any distinctive tonal, impulsive or low frequency characteristics of the noise;

• identification of noise sensitive premises and noise sensitive areas that may be affected;

• the characteristics of the existing noise environment;

• a prediction of how the noise environment will change with the proposed development;

o in the shorter term such as during the construction period; and

o in the longer term during the operating life of the infrastructure.”

The NPS also says the noise impact of activities associated with the development, such as increased road and rail traffic movements, or other forms of transportation, should be considered.

With regards to assessing noise, the NPS states: “Operational noise, with respect to human receptors, should be assessed using the principles of the relevant British Standards and other guidance….. For the prediction, assessment and management of construction noise, reference should be made to any relevant British Standards and other guidance which also give examples of mitigation strategies.”

The NPS states “The project should demonstrate good design through selection of the quietest cost-effective plant available; containment of noise within buildings wherever possible; optimisation of plant layout to minimise noise emissions; and, where possible, the use of landscaping, bunds or noise barriers to reduce noise transmission.”

Proposals must satisfy the following aims:

• avoid significant adverse impacts on health and quality of life from noise;

• mitigate and minimise other adverse impacts on health and quality of life from noise; and

• where possible, contribute to improvements to health and quality of life through the effective management and control of noise.

Mitigation measures may include one or more of the following:

[1] HMSO (2008) ‘The Planning Act’


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• engineering: reduction of noise at point of generation and containment of noise generated;

• lay-out: adequate distance between source and noise-sensitive receptors; incorporating good design to minimise noise transmission through screening by natural barriers, or other buildings; and

• administrative: restricting activities allowed on the site; specifying acceptable noise limits; and taking into account seasonality of wildlife in nearby designated sites.

3.2 National Policy Statement for Fossil Fuel Electricity Generating Infrastructure (EN-2)

In addition to EN-1, the National Policy Statement for Fossil Fuel Electricity Generating Infrastructure (EN-2) has a section relating to noise assessment and mitigation. This supports and strengthens the information held within EN-1. It specifies additional potential sources of noise, including:

• the gas and steam turbines that operate continuously during normal operation; and

• external noise sources such as externally-sited air-cooled condensers that operate continuously during normal operation.

The statement sets out the primary mitigation for noise from fossil fuel generating stations being through good design, including enclosure of plant and machinery in noise-reducing buildings wherever possible and to minimise the potential for operations to create noise. Noise from gas turbines should be mitigated by attenuation of exhausts to reduce any risk of low-frequency noise transmission.

3.3 National Planning Policy Framework (NPPF) The National Planning Policy Framework (NPPF) was introduced in March 2012. The document sets out the Government's planning policies for England and how these are expected to be applied. The NPPF supersedes the previous guidance document PPG 24 'Planning and Noise'.

The planning system is required to contribute to and enhance the natural and local environment. Consequently, the aim is to prevent both new and existing development from contributing to or being put at unacceptable risk from, or being adversely affected by unacceptable levels of noise pollution.

The NPPF states that planning policies and decisions should aim to:

• “avoid noise from giving rise to significant adverse impact on health and quality of life as a result of new development;

• mitigate and reduce to a minimum other adverse impacts on quality of life arising from noise from new development, including through the use of conditions;

• recognise that development will often create some noise and existing businesses wanting to develop in continuance of their business should not have unreasonable restrictions put on them because of changes in nearby land uses since they were established [subject to the provisions of the Environmental Protection Act 1990 and other relevant law]; and

• identify and protect areas of tranquillity which have remained relatively undisturbed by noise and are prized for their recreational and amenity value for this reason”.

With regards to ‘adverse effects’ and ‘significant adverse effects’ the NPPF refers to the Noise Policy Statement for England Explanatory Note (NPSE).


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3.4 Noise Policy Statement for England (NPSE) The Noise Policy Statement for England (NPSE) seeks to clarify the underlying principles and aims in existing policy documents, legislation and guidance that relate to noise. The statement applies to all forms of noise, including environmental noise, neighbour noise and neighbourhood noise, but does not extend to noise in the workplace.

The statement sets out the long term vision of the government’s noise policy, which is to “promote good health and a good quality of life through the effective management of noise within the context of policy on sustainable development”.

The long term vision is supported by three aims:

• “avoid significant adverse impacts on health and quality of life;

• mitigate and minimise adverse impacts on health and quality of life; and

• where possible, contribute to the improvements of health and quality of life”.

The long term policy and vision and aims are designed to enable decisions to be made regarding what is an acceptable noise burden to place on society.

The Explanatory Note within the NPSE provides further guidance on defining ‘significant adverse effects’ and ‘adverse effects’ using the concepts:

• No Observed Effect Level (NOEL) - the level below which no effect can be detected. Below this level no detectable effect on health and quality of life due to noise can be established;

• Lowest Observable Adverse Effect Level (LOAEL) - the level above which adverse effects on health and quality of life can be detected; and

• Significant Observed Adverse Effect Level (SOAEL) - the level above which significant adverse effects on health and quality of life occur.

The three aims can therefore be interpreted as follows:

• The first aim is to avoid noise levels above the SOAEL;

• The second aim considers situations where noise levels are between the LOAEL and SOAEL. In such circumstances, all reasonable steps should be taken to mitigate and minimise the effects. However this does not mean that such adverse effects cannot occur; and

• The third aim considers situations where noise levels are between the LOAEL and NOEL. In these circumstances, where possible, reductions in noise levels should be sought through the pro-active management of noise.

The NPSE recognises that it is not possible to have single objective noise-based measures that define the SOAEL, LOAEL and NOEL that are applicable to all sources of noise in all situations. The levels are likely to be different for different noise sources, receptors and at different times of the day.

3.5 Environment Agency – Horizontal Guidance Note H1 Horizontal Guidance Note H1 provides general guidance and tools to assess risks to the environment and human health when applying for a permit to operate an industrial installation under the Environmental Permitting Regulations (EPR).

The guidance helps explain and justify selected emission control measures by helping applicants to:

• identify potential risks that proposed activity may present to the environment;

• screen out those that are significant and don’t need detailed assessment;

• assess potentially significant risks in more detail, if needed;


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• choose the right control measures, if needed; and

• report the assessment.

3.6 Environment Agency – Horizontal Guidance for Noise Part 2 – ‘Noise Assessment and Control’ IPPC H3

The Environment Agency’s H3 Part 2 Noise Assessment and Control guidance outlines the main considerations relating to the setting of Permit conditions and subsequent regulation of noise from permitted installations. It also provides basic theory on noise, describes the principles of noise measurements and prediction and the control of noise by design, by operational and management techniques and abatement technologies.

3.7 Environment Agency – Noise Impact Assessment – information requirements

The Noise Impact Assessment guidance is a parallel document to the H3 Horizontal noise guidance and helps define the necessary supporting data for noise impact predictions using computer modelling and/or spreadsheet calculations.

3.8 Damhead Creek 2 Power Station – Revised Noise Limits and Noise Monitoring & Management Plan (NMMP)

The Revised Noise Limits and Noise Monitoring and Management Plan (NMMP) document (Issue 2 dated 06 January 2013) was approved under planning permission reference no MC/13/0162 and sets out revised operational noise limits and locations and requires operational noise to be controlled to ensure adequate protection of nearby noise sensitive receptors.

The document also contains the programme for the monitoring and control of noise produced from the proposed DHC2 power station to discharge the requirements of Planning Condition 20, as this also relates to the control of operational noise from the Development. This condition was subsequently discharged on 21st June 2012 (MC/12/1264).

3.9 Damhead Creek 2 Power Station – Construction Environmental Management Plan (CEMP)

The Construction Environmental Management Plan (CEMP) was approved under planning permission MC/15/4047 on 23 December 2015 and details the construction and environmental management for the project to ensure all requirements of the relevant CEMP conditions set within the deemed planning permission are understood, communicated and followed at all times during the construction phase of the project. The CEMP will be subject to continual review to address, for example:

all relevant conditions contained in the deemed planning permission

to ensure it reflects best practise at the time during construction of the CCGT

to ensure it incorporates the findings of pre-construction site investigations

to accommodate the working practises of the principal contractor.

The CEMP outlines measures to be implemented in compliance with the recommendations set out in BS52281, the 2009 ES and the EIRs of 2014 and 2015 in addition to the relevant conditions attached to the Section 90 Direction to minimise noise and vibration during construction.

1 British Standard 5228:2009+A1:2014


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4. Damhead Creek 2 Noise Assessment 4.1 Damhead Creek 2 Proposed CCGT Plant Equipment The proposed 1,800 MW CCGT with peaking plant option will introduce new sources of noise that could potentially affect the surrounding sensitive environment in a different way to the 1800 MW CCGT. A list of key noise generating sources associated with the Proposed Development is as follows:

• 2 x CCGT Gas Turbines;

• Steam Turbine(s);

• 2 x HRSG;

• Feed Water pumps;

• Up to 2 x open cycle gas turbines or Peaking Plant;

• 2 x HRSG Stacks;

• 2 x Peaking Plant Stacks;

• 60 x fans comprising the Air Cooled Condensers (ACC);

• 4 x Peaking Plant Fin Fan Coolers;

• CCGT Fin Fan Coolers;

• 2 x Gas Turbine Air Inlet;

• 3 x Transformers; and

• 1 x Natural Gas Treatment Plant.

It is estimated that the peaking plant will only operate up to 1,500 hours per year. For the purpose of this noise assessment, however, and as a worst case scenario, the simultaneous operation of the CCGT and OCGT has been assessed.

The use of buildings to enclose key items of plant has not yet been finalised and will be at the detailed design stage. Some plant may be placed in enclosures rather than buildings. For the purposes of this assessment therefore, a conservative (minimum) level of noise attenuation has been assumed from the structures around the above plant items.

4.2 Noise Sensitive Receptors The site is located within a predominantly undeveloped and industrial area. The site is bounded by agricultural land to the south, by Damhead Creek, a tidal estuary of the River Medway to the east and by the Kingsnorth Industrial Estate to the west.

The Environmental Statement produced to support the original Section 36 application2 assessed the potential for noise impacts on nearby receptors. The locations of those receptors were agreed during consultation with Medway District Council and are presented below in Table 4-1.

2 Damhead Creek 2 Environmental Statement, Volume 1, June 2009


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Table 4-1: Damhead Creek 2 Environmental Statement – Noise sensitive receptor descriptions

Location Description

1 Residential property Tudor Farm, approximately 1.8 km north north-east of the centre of DHC2.

2 Residential property Polly Adams Cottage, approximately 1.2 km north north-east of the centre of DHC2.

3 Residential property Riverview Cottage, approximately 1.4 km north of the centre of DHC2.

4 Whitehall Farm, approximately 1.1 km north of DHC2.

5 Residential properties on Stoke Road near to lane leading to Whitehall Farm, approximately 1.3 km north north-west of the centre of DHC2.

6 Beluncle Farm and surrounding residential properties, approximately 1.2 km from the centre of DHC2.

7 Sturdee Cottages, approximately 1.9 km from the centre of DHC2.

8 Eschol Lane/Jacobs Lane, approximately 1.3 km from the centre of DHC2.

9 Nature Study Area approximately 1 km from the centre of DHC2.

10 Market Garden/Dog Kennels, approximately 1 km from the centre of DHC2.

Based on the outcome of the assessment presented in the 2009 ES3, monitoring locations were selected to represent nearby noise sensitive receptors, and noise limits were set as part of the NMMP, as follows:

• Point A – 400 m north of DCH1 ACC4;

• Point B – 400 m east of DCH1 ACC;

• Point D1 – 400 m west of DCH1 ACC;

• Point G – Eschol Lane / Jacobs Lane.

Figure 4-1 presents the monitoring locations as identified in the NMMP. In order to assess whether the proposed section 36 variation could give rise to any greater impacts than the already consented DHC2 scheme, this assessment focusses on these agreed receptor monitoring locations.

3 Damhead Creek 2 Environmental Statement, Volume 1, June 2009 4 Description of locations is provided in Damhead Creek Power Station – Application for a Pollution Prevention and Control Permit

(PPC Permit), Final Report, March 2006


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FIGURE 4-1: NMMP MONITORING LOCATIONS (TAKEN FROM THE NMMP)

With regard to Point B, it has been agreed with Medway Council that no monitoring is required at this location if the 1,800 MW scheme (either CCGT only or with peaking plant option) is constructed, as this location will be within the Proposed Development footprint, and there are no residential receptors in the vicinity of this monitoring location. This is reflected in the wording of Condition 20 and 21 of the current Section 90 Direction. As a result of this agreement, Point B has been excluded from this noise assessment.

The revised NMMP presents maximum noise levels for DHC1 and also establishes maximum noise levels for DHC1 and DHC2 combined. Based on the information provided in the NMMP, the free-field equivalent continuous A-weighted sound pressure level at the noise monitoring locations caused by the operation of Damhead Creek (both plants) during its normal commercial operation measured over a period of 5 minutes shall not exceed the values in Table 4-2.

Table 4-2: NMMP Revised Damhead Creek Noise Limit Levels

Location X Y Description Noise level

during operation of DHC 1 LAeq, 5

min (dB)

Noise level during operation

of DHC1 & 2 LAeq, 5 min (dB)

Point A 581000 173267 North Point 46 50

Point B* 581416 172867 East Point 46 55

Point D1 580670 172885 West Point 46 50

Point G 172534 172534 Eschol Lane / Jacobs Lane 37 40

* Point B location and associated noise limits are excluded from the assessment

It should be noted that the noise limits presented in Table 4-1 assume that noise from the operation of DHC1 and DHC2 at any of the above receptors does not contain tonal or intermittent properties. If operational noise contains tonal or intermittent properties then the noise limits would need to be


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reduced by 5 dB to account for the potential additional disturbance that may result from these noise properties.

In the absence of the original noise model used to establish the NMMP noise limits, the equivalent noise limits for the operation of DHC2 have been calculated based on the NMMP noise limits provided for the combined operations of DHC1 and DHC2. Calculations were carried out by logarithmically subtracting NMMP noise limits for the operation of DHC1 only at each receptor (assuming DHC1 operates at its noise limits) from the combined noise limits when both DHC1 and DHC2 are operating. These calculated noise limits then formed the basis for the DHC2 noise impact assessment at the NMMP monitoring locations; see Table 4-3.

Table 4-3: Damhead Creek 2 Calculated Noise Limits

Location X Y Description Noise limit during operation of DHC2

LAeq, 5 min (dB)

Point A 581000 173267 North Point 48

Point B* 581416 172867 East Point 54

Point D1 580670 172885 West Point 48

Point G 172534 172534 Eschol Lane / Jacobs Lane 37

* Point B location and associated noise limits are excluded from the assessment

In addition to noise at nearby residential receptors, due to the close proximity of the proposed power station to existing nature conservation sites, the potential impact of the operation of DHC2 on designated habitats in the area has also been considered.

AECOM requested an Environment Agency screening report5 for the site, which identified several designated nature conservation sites within a screening distance of 10 km. The details of these sites are presented in Table 4-4.

Table 4-4: Damhead Creek 2 Nature Conservation Sites (EA Screening report)

Receptor Name Designation/Use Direction from Site

Distance to Receptor

Screening Distance

Medway Estuary & Marshes

Special Protection Areas (SPA), RAMSAR and Sites of Special Scientific Interest (SSSI)

East, South and West

Adjacent East, 950m and 1,600m

2 km

Thames Estuary & Marshes

Special Protection Areas (SPA)

North and East

5,000m and 9,000m 10 km

The Swale Special Protection Areas (SPA) and RAMSAR East 11,000m 10 km

Queendown Warren

Special Areas of Conservation (SAC) South 10,000m 10 km

The locations of the nature conservation sites have also been identified on maps provided by the Environment Agency and are presented in Annex C.

5 Environment Agency, Nature and Heritage Conservation, Screening Report: Bespoke installations, 26 September 2014 (ref:

EPR/VP3133LP/V003)


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4.3 Potential Noise Control Measures Operation of a well-designed gas fired power station is not an inherently noisy process. However, to meet the agreed noise limits as defined in the agreed NMMP, appropriate noise control measures must be considered.

The level of noise control that was proposed to be introduced on DHC2 is described in the Environmental Statement submitted in support of the original Section 36 application6. The DHC2 project has not yet reached the end of the detailed design process, and as such specific information on certain design aspects has not been finalised. For the purpose of the noise modelling undertaken for this assessment and based on provided information on proposed plant, it is assumed that appropriate noise control measures are to be incorporated in the design for DHC2 (for either the 1,800 MW CCGT only or with peaking plant options). Such noise control measures could include:

• use of individual acoustic enclosures (which may, or may not be buildings) for the gas turbines;

• use of silencers for gas turbine filter and ventilation where these face towards sensitive receptors;

• specifically for the peaking plant gas turbines, noise from the proposed inlets will be controlled through noise attenuation measures as required to achieve a maximum sound power level of Lw 100 dB(A);

• low noise air cooled condensers will be used;

• unit transformers and generator transformers will be housed in an appropriate enclosure or three sided pen, to provide screening to noise sensitive receptors;

• the use of acoustic panels/enclosures with absorbent inner linings and barriers will be incorporated in the design where necessary;

• the use of an acoustic barrier will be incorporated in the design of the gas treatment plant. The barrier must be designed to attenuate noise emissions to a sound pressure level of 70 dB(A) at a distance of 1m from the barrier; and

• all plant items shall be controlled to minimise noise of an impulsive or tonal nature, such that the rating level as defined is BS 4142 is equal to the specific noise level.

Routine maintenance of plant and equipment will be undertaken as part of a formal preventative maintenance procedure. As discussed in Section 4.4, the sound power data used in the noise modelling exercise (see Table 4-4) assume the above described level of noise control to be adopted.

4.4 Noise Modelling Noise modelling has been utilised to predict the resultant levels at the agreed monitoring locations, designated ecological sites and general surrounding area. Datakustik CadnaA predictive computer noise modelling software has been utilised which implements the ISO 96137 prediction methodology. The model takes into consideration all the identified potential noise sources listed in Section 4.1, distance propagation and screening effects due to the presence of existing buildings (e.g. DHC1).

The receptor grid for noise impacts has been set at 1.5 m above local grid to represent typical ear height for occupants of nearby sensitive receptors.

The following has been assumed in the noise modelling:

• The noise model was based on information on proposed plant and associated noise emission data provided by ScottishPower. Main noise sources and associated sound power/pressure data included in the model are presented in Table 4-5.

6 Damhead Creek 2 Environmental Statement, Volume 1, June 2009 7 ISO 9613, Acoustics - Attenuation of sound during propagation outdoors, Parts 1-2


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Table 4-5: Damhead Creek 2 Plant Sound Power/Pressure Levels

Noise Source Source Sound Power Lw (dB)

Source Sound Pressure SPL (dB) – internal

reverberant No of Source Height

(m)

Gas Turbine 85 2 30

Steam Turbine 85 1 25

HRSG Enclosure 82 1 45

Feed Water Pumps 100 1 9

Peaking Plant GT 85 2 20

HRSG Stack 84 2 95

Peaking Plant Stack 84 2 50

Air Cooled Condenser 88 60 46.5

Peaking Plant Fin Fan Coolers 103 4 set of fans 7

CCGT Fin-Fan Coolers 103 1 8

Gas Turbine Air Inlet (peaking plant) 100 2 11

Transformer 89-95 3 3

Gas Treatment plant (all sources) 110 1 1.5

• Predictions assume the level of noise control described in the Damhead Creek 2 Environmental Statement submitted in support of the original Section 36 consent application and those presented in Section 4.3 of this report. All noise attenuation data provided on the design of the plant have been incorporated in the noise model.

• A provisional layout for the proposed 1,800 MW CCGT with peaking scheme option has been prepared to inform the assessments and the Section 36 variation application. This layout and associated structure dimensions have been utilised for the noise modelling, see Annex B for the proposed site layout used in the modelling assessment.

• Information on DHC2 site ground topography used in the model was based on drawing (ref: SP002/EGL01 dated 26.02.14); wider area topography data were taken from the Ordnance Survey Open Database.

• Due to the limited operation of the peaking plant (up to 1,500 hours per year), a 5 dB penalty for intermittency has been conservatively applied to predicted noise levels of the peaking plant at the nearest sensitive receptors given the likely intermittent nature of the operation.

• DHC1 building heights were based on height information provided in the Environmental Statement submitted in support of the original Section 36 application for DHC28 and buildings were incorporated in the model to consider the potential screening provided.

8 Damhead Creek 2 Environmental Statement, Volume 2, June 2009


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4.5 Noise Impact Assessment on Receptor Monitoring Locations The output from the noise model has been interpreted and a contour plot developed which shows the noise contours across the DHC2 site and surrounding environment. This plot is provided in Annex D. Noise levels were calculated on a 5 m grid, at a height of 1.5 m above local grid.

Calculated free-field noise levels as a result of the operation of DHC2 only (assuming 1,500 MW CCGT plus 300 MW OCGT) at the defined monitoring locations presented in Table 4-2, are summarised in Table 4-6.

Table 4-6: Summary of Calculated Results at the Receptor Monitoring Locations from the Operation of DHC2 only (1,800 MW CCGT with peaking plant scheme option).

Location X Y Description

Calculated Noise level

during operation of only DHC2 LAeq,T dB

NMMP Noise limit

during operation

of only DHC2 LAeq,T

dB*

Calculated Noise level

during operation of DHC1

and DHC2***

LAeq,T dB

NMMP Noise limit

during operation of DHC1 & 2 LAeq, 5 min (dB)

Point A 581000 173267 North Point 45** 48 49 50

Point D1 580670 172885 West Point 43** 48 48 50

Point G 172534 172534 Eschol Lane / Jacobs Lane 37 37 40 40

* Noise limits during operation of DHC2 only are based on NMMP limits and were calculated by logarithmically subtracting noise limit levels at each receptor during only the operation of DHC1 from the combined noise limits when both DHC1 and DHC2 are operating. ** A 5dB penalty for intermittency has been added to levels from the peaking plant to calculate the rating noise level at Points A and D1.

*** This calculation assumes DHC1 operates at its limit as defined in NMMP and has not been specifically modelled as part of this assessment

Predicted results in Table 4-6 at monitoring locations A and D1 include a 5 dB penalty on noise levels from the peaking plant as a result of its intermittent use. Noise from the operation of the peaking plant will not be audible at receptor monitoring location G, therefore the penalty is not applied to this location.

Comparison between predicted noise levels solely from the operation of the proposed 1,800 MW CCGT with peaking scheme option, at the selected noise monitoring locations and the equivalent noise limits, as calculated from NMMP limit values, indicates that noise levels arising from DHC2 will be within the compliance limits for all locations and that when combined with DHC1 noise, the combined noise will be within the limits set for both plants.

These assessment results are considered to be conservative, as they are based on the assumption that the DHC1 is operating to its limit with regards to noise generation. Based on ScottishPower future plans for the power stations, the operation of DHC1 is envisaged to more realistically be reduced to approximately 50% load factor over time.

4.6 Noise Impact Assessment on Designated Nature Conservation Sites The potential noise impact of the proposed activities on designated nature conservation sites has been reviewed using the outputs from the noise model study. The highest exposure levels predicted at the nearest designated site (Medway Estuary & Marshes SSSI and SPA) from the operation of DHC2-only were predicted to be between 45-49 dB(A). These levels were predicted for a small area of the


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designated site to the east and south-east of the proposed DHC2 power station and only when the peaking plant is in operation. Worst case predicted noise levels at the nearest designated nature conservation site when the peaking plant is not in operation was calculated at 48 dB(A). The combined operation with DHC1 has not been modelled, however DHC2 would be the dominant noise source at this location and no contribution would be expected from DHC1 at the receptor.

Predictions indicate that the main area of the closest designated site (>95% of the site area) will be exposed to noise levels below 35 dB(A) as a result of DHC2 in full operation. A noise contour plot indicating the location of the nearest Habitats site to the Site is presented in Annex E.

A comparison of the noise modelling results and the NMMP noise limits set for the operation of DHC1 indicates that noise emissions from the operation of DHC2 would result in an increase in noise levels of potentially up to 10 dB(A) over a small area of the nearest designated nature conservation site, to the south-east of DHC2 (Medway Estuary & Marshes). Based on available information regarding noise tolerance of the species known to use the SPA and the area of habitat potentially affected, this is not considered to be a significant effect (see Appendix H to the EIR, Habitats Regulations Assessment Review) Further away from DHC2 (further to the south east), noise level impacts from the installation will decrease with distance until they reach background noise levels, resulting in no audible increase in noise levels from the operation of DHC2. No other designated nature conservation sites are predicted to be affected. This level of change is not considered to be significant, as outlined in the Habitats Regulations Assessment Review that forms Appendix H to the EIR.

DHC2 CHP Readiness Report 4-Feb-16

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5. Conclusions AECOM has been engaged by ScottishPower (DCL) Limited to provide a noise impact assessment to support the application for a variation to the existing Section 36 consent for the Damhead Creek 2 (DHC2) Power Station in Kent. The Section 36 variation is required to incorporate the proposed changes in the make-up of the plant to potentially include up to 300 MW of OCGT peaking plant, which, when combined with the proposed CCGT units, together will continue to provide up to 1,800 MW of electrical generating capacity at the Site. The existing consented 1800 MW CCGT option only will be retained. A noise modelling study has been carried out to assess the impact of the proposed 1,800 MW CCGT with peaking plant scheme option on nearby agreed noise monitoring locations and sensitive receptors. The results of the noise modelling indicate that predicted noise levels at all noise sensitive receptors around the site will be below the noise limits for DHC2 only as calculated from the agreed Noise Monitoring and Management Plan (NMMP) for the combined DHC1 and DHC2 power stations. This assumes that sufficient noise control measures will be adopted as part of the detailed plant design for DHC2 as defined in Section 4.3 of this report, and the equipment will be designed to achieve the noise power levels defined in Table 4-5. Predicted results also assume the use of suitable silencers are likely to be required for the peaking plant gas turbine inlets and the construction of a barrier around the gas treatment plant to meet noise outputs defined in Section 4.3, though the specific mitigation to be applied will be determined during the detailed design and presented to support the environmental permit application for the facility. Noise levels from the operation of DHC2 only, at Habitats sites around the installation (including Medway Estuary & Marshes SSSI and SPA) were predicted to be below 55 dB(A). The majority of the designated Habitat (>95% of the site area) will be exposed to levels below 35 dB(A) and noise emissions from the proposed power station will decrease until they reach background noise levels resulting in no audible increase in noise levels solely from the operation of DHC2. A Habitats Regulations Assessment review has been undertaken to support the Section 36 variation application (Appendix H to the Environmental Information Report) which concludes no likely significant effect on any Natura 2000 sites as a result of the predicted noise changes arising from the implementation of the proposed development. On this basis, the currently proposed techniques to minimise or control noise emissions from the installation are considered to represent BAT in relation to noise management and are not predicted to result in any significant offsite noise impacts.


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Limitations

AECOM Infrastructure & Environment UK Limited (hereafter referred to as AECOM, formerly known as URS) has prepared this Report for the sole use of ScottishPower DCL Limited (“Client”) in accordance with the Agreement under which our services were performed (Proposal No. P858641, dated 19th September 2014). No other warranty, expressed or implied, is made as to the professional advice included in this Report or any other services provided by AECOM. This Report is confidential and may not be disclosed by the Client nor relied upon by any other party without the prior and express written agreement of AECOM.

The conclusions and recommendations contained in this Report are based upon information provided by others and upon the assumption that all relevant information has been provided by those parties from whom it has been requested and that such information is accurate. Information obtained by AECOM has not been independently verified by AECOM, unless otherwise stated in the Report.

The methodology adopted and the sources of information used by AECOM in providing its services are outlined in this Report. The work described in this Report was undertaken between October 2014 and December 2015 and is based on the conditions encountered and the information available during the said period of time. The scope of this Report and the services are accordingly factually limited by these circumstances.

Where assessments of works or costs identified in this Report are made, such assessments are based upon the information available at the time and where appropriate are subject to further investigations or information which may become available.

AECOM disclaim any undertaking or obligation to advise any person of any change in any matter affecting the Report, which may come or be brought to AECOM’s attention after the date of the Report.

Certain statements made in the Report that are not historical facts may constitute estimates, projections or other forward-looking statements and even though they are based on reasonable assumptions as of the date of the Report, such forward-looking statements by their nature involve risks and uncertainties that could cause actual results to differ materially from the results predicted. AECOM specifically does not guarantee or warrant any estimate or projections contained in this Report.

Where field investigations are carried out, these have been restricted to a level of detail required to meet the stated objectives of the services. The results of any measurements taken may vary spatially or with time and further confirmatory measurements should be made after any significant delay in issuing this Report.

Copyright

© This Report is the copyright of AECOM Infrastructure & Environment UK Limited, a wholly owned subsidiary of AECOM. Any unauthorised reproduction or usage by any person other than the addressee is strictly prohibited


Annex A – Glossary of Terms


For the purposes of this report, the following terminology and abbreviations are used:

• dB(A) – The unit of noise measurement that expresses the loudness in terms of decibels (dB) based on a weighting factor for humans sensitivity to sound (A);

• Hz – Hertz (unit of frequency);

• LA1, LA5, LA10, LA50, LA90, LA99 – A-weighted sound pressure level exceeded for 1, 5, 10, 50, 90 or 99% of the measured time;

• LAeq – Equivalent continuous A-weighted sound pressure level over a given period of time;

• Lw – Sound power level - the rate at which sound energy is emitted, reflected, transmitted or received, per unit time; and

• SPL – Sound Pressure Level - a ratio of the absolute (RMS) sound pressure and a reference level (usually the Threshold of Hearing, or the lowest intensity sound that can be heard by most people).

Where decibel (dB (A)) levels are followed by a given noise indicator (e.g. LAeq), then the annotation will read as dB LAeq.


ANNEX B:

PROPOSED SITE LAYOUT



ANNEX C:

ENVIRONMENT AGENCY - NATURE AND

HERITAGE CONSERVATION SITE MAPS




Ramsar Sites



ANNEX D:

NOISE CONTOURS

DHC2 Environmental Information Report 4-Feb-16


ANNEX E:

NOISE CONTOURS – HABITATS SITES


Documents

NOISE ASSESSMENT REPORT SECTION 36C VARIATION … · figure 2-1: site location of damhead creek ccgt 1 & 2 power stations The proposed development is the construction and operation