5 Noise Impact Assessment

5.1 Introduction

This Section assesses the potential noise impacts to the identified Noise Sensitive Receivers (NSRs) associated with the construction and operation of the Project in accordance with the requirements stated in Sections 3.4.3 and 3.4.7 of the EIA Study Brief. Mitigation measures are recommended where potential noise impacts are identified.

5.2 Baseline Conditions

The Project Site is located in an urban area in Central. The Site is located in an urban area in Central and covered by the Sai Ying Pun & Sheung Wan Outline Zoning Plan No. S/H3/24. It has been zoned as “OU” annotated “Historical Site Preserved for Cultural, Recreational and Commercial Uses”. The surrounding area of the Site has been zoned as Residential (Group A) (R(A)), Commercial (C) and Open Space (O).

Background noise levels are typical of a general urban environment. The major existing noise sources were identified as traffic noise from local roads Hollywood Road, Wyndham Street and Old Bailey Street.

To investigate the prevailing noise levels of the Study Area (300m from the Project Site boundary, as shown in Figure 5.1) , noise measurements were taken on 7 to 8 October 2009. The noise measurements were conducted using a SVAN 949 Sound Level Meter (Type 1) and a Solo 01 Premium Sound Level Meter (Type 1), which had been calibrated using a SVAN Sound Level Calibrator Type 4231 and a SVAN SV 30A Sound Level Calibrator respectively, with a calibration signal of 94.0 dB(A) at 1kHz. Two microphones were set at 1m from the building façade of the Barrack Block of the CPS and Chancery House. The measurements were conducted in accordance with the calibration and measurement procedures stated in the Technical Memorandum on Noise From Places Other than Domestic Premises, Public Places or Construction Sites (IND-TM). The measurement locations are shown in Figure 5.2 and the measured prevailing background noise levels are summarised in Table 5.1.

Table 5.1 Measured Prevailing Background Noise Levels

Measurement Location	Time Periods	Measured Noise Levels, dB(A)
Barrack Block of the CPS	Day-time: 07:00 to 11:00 hrs	59 – 63
	19:00 to 23:00 hrs	59 – 61
	Night-time: 23:00 to 07:00 hrs	54 – 59
Chancery House	Day-time: 07:00 to 11:00 hrs	54 – 58
	19:00 to 23:00 hrs	55 – 57
	Night-time: 23:00 to 07:00 hrs	49 – 55

5.3 Legislative Framework

5.3.1 Construction Noise

The principal legislation relating to the control of construction noise is the Environmental Impact Assessment Ordinance (EIAO) (Cap. 499). The Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM), issued under the EIAO, provides guidelines and noise criteria for evaluating the potential noise impact.

The Noise Control Ordinance (Cap. 400) (NCO) also provides means to assess the construction noise impact. Various Technical Memoranda (TMs), which stipulate control approaches and criteria, have been issued under the NCO. The following TMs are applicable to the control of noise impact from construction activities:

· Technical Memorandum on Noise from Construction Work other than Percussive Piling (GW-TM); and

· Technical Memorandum on Noise from Construction Work in Designated Areas (DA-TM).

General Construction Works

Under the EIAO, potential noise impact arising from general construction works during normal working hours (ie 07:00 to 19:00 hrs on any day not being a Sunday or public holiday) at 1m from the external façade of the uses, which rely on opened windows for ventilation, is to be assessed in accordance with the noise criteria specified in the EIAO-TM. The EIAO-TM noise standards are presented in Table 5.2.

Table 5.2 EIAO-TM Day-time Construction Noise Standards (L_{eq, 30 min} dB(A))

Use	Noise Standard (dB(A))
Domestic Premises	75
Educational Institutions (normal periods) Educational Institutions (during examination periods)	70 65
Notes: (a) The above standards apply to uses which reply on opened windows for ventilation. (b) The above standards shall be viewed as the maximum permissible noise levels assessed at 1m from the external façade.

When assessing a Construction Noise Permit (CNP) application for the use of Powered Mechanical Equipment (PME) during the restricted hours, the Noise Control Authority will compare the Acceptable Noise Levels (ANLs), as promulgated in GW-TM, and the Corrected Noise Levels (CNLs) (ie after accounting for factors such as barrier effects and reflections) associated with the proposed PME operations. The ANLs are obtained with corrections for the duration of the CNP and multiple permit situations, if applicable, to the Basic Noise Levels (BNLs). The BNLs are related to the noise sensitivity of the area in question and different Area Sensitivity Ratings (ASR) have been established to reflect the background characteristics of different areas. The appropriate ASR for the NSR is determined with reference to Table 5.3.

Table 5.3 Area Sensitivity Ratings

Types of Area Containing NSR	Degree to which NSR is affected by Influencing Factor (IF)
	Not Affected	Indirectly Affected	Directly Affected
Rural area, including Country Parks or village type developments	A	B	B
Low density residential area consisting of low-rise or isolated high-rise developments	A	B	C
Urban area	B	C	C
Area other than those above	B	B	C
Notes: The following definitions apply: (a) "Country Park" means an area that is designated as a country park pursuant to section 14 of the Country Parks Ordinance; (b) "directly affected" means that the NSR is at such a location that noise generated by the IF is readily noticeable at the NSR and is a dominant feature of the noise climate of the NSR; (c) "indirectly affected" means that the NSR is at such a location that noise generated by the IF, whilst noticeable at the NSR, is not a dominant feature of the noise climate of the NSR; (d) "not affected" means that the NSR is at such a location that noise generated by the IF is not noticeable at the NSR; and (e) "urban area" means an area of high density, diverse development including a mixture of such elements as industrial activities, major trade or commercial activities and residential premises.

The relevant BNLs are shown in Table 5.4.

Table 5.4 Basic Noise Levels for General Construction Works (BNL, L_{eq, 5 min} dB(A))

Time period	Area Sensitivity Rating (dB(A))
	A	B	C
All days during the evening (ie 19:00-23:00 hrs) and general holidays (including Sundays) during the day and evening (ie 07:00-23:00 hrs)	60	65	70
All days during the night-time (ie 23:00-07:00 hrs)	45	50	55

The Noise Control Authority will consider a well-justified CNP application, for construction works within restricted hours as guided by the relevant TMs issued under the NCO. The Noise Control Authority will take into account adjoining land uses and any previous complaints against construction activities at the site before making a decision. Nothing in this EIA Report shall bind the Noise Control Authority in making its decision. The Noise Control Authority may include any conditions in a CNP that it considers appropriate. Failure to comply with any such conditions may lead to cancellation of the CNP and prosecution action under the NCO.

5.3.2 Operational Noise

Fixed Noise Sources

The EIAO-TM and IND-TM specifies the applicable ANLs for the fixed plant noise impacts from a development.

The ANLs are dependent on the ASR and the time of the day and are presented in Table 5.5.

Table 5.5 ANLs depending on the ASR

Time Period	Leq 30min (dB(A))
	ASR “A”	ASR “B”	ASR “C”
Daytime 07:00-19:00 hrs	60	65	70
Evening 19:00-23:00 hrs	60	65	70
Night-time 23:00-07:00 hrs	50	55	60

Fixed plant noise is controlled under Section 13 of the NCO and the predictions will be undertaken in accordance with the IND-TM. The criteria noise limits for planning purposes are set out in the EIAO-TM as follows:

· the total fixed source noise level at the facade of the nearest NSR is at least 5 dB(A) lower than the appropriate ANL (as shown in Table 5.5) as specified in the IND-TM; or

· the prevailing background noise level (for quiet areas with level 5 dB(A) below the ANL).

The noise criteria stipulated in the IND-TM are dependent on the ASR of the NSRs. As the NSRs in the vicinity of the Site are located in an urban area and are not affected by any Influencing Factor, the ASR “B” has been assumed for these NSRs. Background noise measurement was conducted to investigate the prevailing noise level in the Study Area (see Table 5.1). The operational noise criteria are determined and presented in Table 5.6.

Table 5.6 Operational Noise Criteria

Representative NSR	Measurement Point	Time Periods	Minimum Measured Background Noise Levels, dB(A), [1]	ANL-5, dB(A), [2]	Operational Noise Criteria in this EIA, Minimum of [1] or [2], dB(A)
N1-N3	Barrack Block of the CPS	Day-time/Evening time	59	60	59
		Night-time	54	50	50
N4-N6	Chancery House	Day-time/Evening time	54	60	54
		Night-time	49	50	49

In any event, the noise criteria employed in this EIA Report is for indicative assessment only. It should be noted that fixed noise sources are controlled under Section 13 of the NCO. At the time of investigation, the Noise Control Authority shall determine noise impact from concerned fixed noise sources on the basis of prevailing legislation and practices being in force, and taking account of contemporary conditions / situations of adjoining land uses.

5.4 Noise Sensitive Receivers

In accordance with the requirements stated in Section 3.4.3.1 of the EIA Study Brief, the Study Area for the noise impact assessment covered an area of 300m from the Site. Only the first layer of NSRs located along the Site boundary was included in the assessment as the NSRs behind were located further away from the road and were screened. The area considered in the assessment is shown in Figure 5.1.

The selected existing representative NSRs that may potentially be affected by the construction of the Project include Amber Lodge, Ho Fook Building, Old Bailey Street Police Married Quarters, Cambridge Villa, Chancery House and Chancery Mansion. No planned NSRs were identified within the Study Area.

As the existing structures within the CPS and the new buildings will be installed with centralised air-conditioning system, they are considered as noise non-sensitive uses.

The locations of the identified representative NSRs are presented in Figure 5.2.

Descriptions of the representative NSRs are provided in Table 5.7.

Table 5.7 Representative Noise Sensitive Receivers (NSRs)

NSR	Name	Type of Usage	No. of Storeys
N1	Amber Lodge	Residential	18
N2	Ho Fook Building	Residential	5
N3	Old Bailey Street Police Married Quarters	Residential	24
N4	Cambridge Villa	Residential	11
N5	Chancery House	Residential	6
N6	Chancery Mansion	Residential	15

5.5 Potential Sources of Impact

5.5.1 Construction Phase

Potential impacts to the NSRs during the construction phase of the Project will mainly arise from the use of PME. The major construction activities will include:

· Small-scale demolition of sub-standard ancillary structures and walls;

· Foundation works for the new buildings, construction of the basements at the lower courtyard, and construction of tunnels under A Hall and B Hall and M&E trenches;

· Construction of new buildings, including the Old Bailey Wing and the Arbuthnot Wing adjacent to the upper courtyard; and

· Modification/refurbishment works of the existing building.

The normal working hours of the construction works will be between 07:00 and 19:00 hrs from Monday to Saturday (except general holidays). Should evening and night works between 19:00 and 07:00 hrs or on public holidays (including Sundays) be required, the Contractor will submit a CNP application which will be assessed by the Noise Control Authority.

5.5.2 Operation Phase

Fixed Plant Noise

As described in Section 2.5.3, the E&M facilities will be centralised under the lower courtyard, at the Arbuthnot Wing and the Ablution Block.

Potential sources of noise impacts are identified as the mechanical equipment associated with the operation of the revitalised CPS. All mechanical equipments will be housed within plant rooms except the fan discharge of cooling towers at the rooftop of the Arbuthnot Wing. A total of 3 cooling towers will be provided and they will be operated during the day-time and evening time periods (ie, within 07:00 to 23:00 hrs); while only 2 cooling towers will be operated during the night-time period (ie, 23:00 to 07:00 hrs of the next day).

Since detailed design of the equipment to be installed within the plant rooms is not yet available, the maximum allowable sound power levels (SWLs) emitted from the plant rooms have been calculated using the fixed plant noise criteria to be compliant with the noise criteria set out in Section 5.3.2. The maximum allowable SWLs of the equipments employed in the fixed plant noise assessment, as presented in Annex B3, has been vetted and confirmed by the engineer as being practicable.

Noise Emissions from Public Address (PA) System

During the operation phase of the Project, outdoor events with the use of PA system may be held at the lower courtyard and upper courtyard during some special occasions during daytime and evening period (until 23:00 hrs).

The PA system at the Site will be temporary and demountable based on the nature of the outdoor events, and there is no confirmed design at this stage. However, the power and number of speakers at the lower courtyard are expected to be small. For the purpose of assessment, it is assumed that 6 speakers will be provided, the maximum allowable SWLs from the PA system has been calculated. In view of the fact that the design of the PA system will be different from case to case, each independent event organizers will be specified that at the time of each event shall not exceed the total sound power level. Also, the contract document will specify the requirement of noise monitoring in place during the event to ensure compliance with the noise criterion at the NSRs.

Noise Emissions from Indoor Musical Performance

Musical performance at some of the multipurpose spaces may be held occasionally. During the detailed design stage, an acoustic consultant will be appointed to provide recommendations on the acoustic design such that the corresponding design criteria of specific space type would be met. As the musical performance will be held within fully enclosed area and appropriate acoustic treatment, such as absorptive wall finishing, upgraded window insulation, etc. will be provided as necessary, adverse noise impact from the indoor musical performance is not anticipated. Annex B3 shows the locations of fixed plant items. The maximum allowable SWLs of the mechanical equipments and the PA system presented in Annex B3 should be included in the tender specification to ensure that the assumptions for the operational noise impact assessment will be implemented. The suppliers of equipment should guarantee the specified SWLs, with the characteristics of tonality, impulsiveness and intermittency accounted for, by providing certificate of measurement and verify the SWL during testing and commissioning in accordance with international standard procedures. If necessary, the suppliers should apply attenuation measures (eg use of silencers) to achieve the guaranteed noise levels during the detailed design stage.

5.6 Assessment Methodology

5.6.1 Construction Phase

The construction noise impact assessment was undertaken in accordance with the procedures outlined in the GW-TM, which is issued under the NCO and the EIAO-TM. The assessment methodology is summarised as follows:

· Identify the representative NSRs that may be affected by the construction of the Project;

· Determine the plant teams for corresponding construction activities, based on the agreed plant inventory;

· Assign SWLs to the PME proposed based on the GW-TM, British Standard BS 5228 ([1]) and list of SWLs of other commonly used PME ([2]);

· Calculate the correction factors based on the distance between the NSRs and the notional noise source position of the work areas;

· Apply corrections in the calculations, such as potential screening effects and acoustic reflection, if any; and

· Predict the construction noise levels at NSRs in the absence of any mitigation measures.

The construction noise assessment was undertaken based on the proposed construction works programme and plant inventory, and appropriate utilisation rates of the PME items (see Annexes B1 and B2). The CPS Ltd and its engineering consultants has reviewed the programme and plant inventory, and have confirmed that they are reasonable and practicable for completing the Project within the scheduled timeframe. The proposed methods for the construction of the Project are common in Hong Kong and the PMEs proposed are available in the Hong Kong market. 

The Project Site is shown in Figure 5.2. The total SWL associated with each construction activity was established. The potential noise impacts at NSRs were evaluated by comparing the predicted noise levels with the EIAO-TM day-time construction noise limits (L_{eq, 30min} dB(A)), as outlined in Section 5.3.1.

5.6.2 Operation Phase

Fixed Noise Sources

The methodology for the fixed plant noise impact assessment follows the procedures outlined in the IND-TM. The methodology is summarised as follows:

· Identify types of equipment and the number of equipment (if available);

· Calculate the maximum SWL for each type of equipment;

· Identify representative NSRs that may be affected by the fixed plant;

· Calculate the correction factor, using a conservative approach, based on the horizontal distance between the NSRs and the fixed plant sources;

· Calculate the maximum allowable SWLs of the plant room louvers by adopting standard acoustics principles; and

· Present the results in terms of L_{eq, 30min} dB(A), as specified in the IND-TM.

All equipment will be operated during the day-time and evening time periods (ie within 07:00 to 23:00 hrs), while some of the equipments, as presented in Annex B3, will be operated during the night-time period (ie within 23:00 to 07:00 hrs).

The assessment has also taken into account the facade correction of +3 dB(A). The predicted noise levels at the NSRs are compared with the criterion set out in Section 5.3.

5.7 Construction Phase Impact

The predicted construction noise levels during day-time period for the construction of the Project are presented in Table 5.8. Summaries of the predicted noise levels and details of the noise calculations are presented in Annex B2.

Table 5.8 Predicted Construction Noise Levels during Day-time Period (Without Mitigation)

NSR	Description	Predicted Construction Noise Levels^(a), Leq, 30 min dB(A)
N1	Amber Lodge	79 - 86
N2	Ho Fook Building	80 - 87
N3	Old Bailey Street Police Married Quarters	81 - 86
N4	Cambridge Villa	84 - 87
N5	Chancery House	86 - 89
N6	Chancery Mansion	86 - 89
Notes: (a) All predicted noise levels were corrected with 3dB(A) for façade reflection. (b) Bold value indicates exceedance of noise criteria of 75 dB(A) for residential premises.

5.8 Operation Phase Impact

Based on the calculated maximum allowable SWLs for the plant rooms and the exhaust fans, the predicted fixed plant noise levels at the representative NSRs are summarised in Tables 5.9 and 5.10 for day-time and evening time period, and night-time period, respectively. Details of calculation are presented in Annex B3. The predicted noise levels at the representative NSRs would comply with the noise criteria as discussed in Section 5.3.2.

Table 5.9 Predicted Operational Noise Levels during Day-time / Evening Time Period

NSR	Description	Predicted Operational Noise Levels, Leq, 30 min dB(A)	Operational Noise Criterion, dB(A)
N1	Amber Lodge	53	59
N2	Ho Fook Building	52	59
N3	Old Bailey Street Police Married Quarters	56	59
N4	Cambridge Villa	53	54
N5	Chancery House	54	54
N6	Chancery Mansion	54	54

Table 5.10 Predicted Operational Noise Levels during Night-time Period

NSR	Description	Predicted Operational Noise Levels, Leq, 30 min dB(A)	Operational Noise Criterion, dB(A)
N1	Amber Lodge	42	50
N2	Ho Fook Building	48	50
N3	Old Bailey Street Police Married Quarters	48	50
N4	Cambridge Villa	43	49
N5	Chancery House	48	49
N6	Chancery Mansion	49	49

It should be noted that the operational noise assessment presented above is based on a worst-case scenario in which the equipment are assumed to be operated simultaneously, which is unlikely to occur in real situation.

The fixed plant noise emission should be controlled to comply with the designated day-time and evening-time noise criteria measured at 1m from the openings of the nearby NSRs in accordance with the IND-TM (details are given in Section 5.3). A detailed noise impact assessment should be undertaken during the detailed design of the fixed plant items. The above requirements and the maximum specified SWLs for the plant rooms, exhaust fans and PA system presented in Annex B3 will be included in the contract specification to be issued to suppliers or contractors for the equipment. The Project Proponent has committed that the maximum allowable SWL emitted from the PA system and the requirements on noise monitoring for the events at the courtyards will be specified in the contract documents for each event. The event organizers will be required to design the events such that the noise emissions from the speakers will comply with the relevant statutory noise limits. With the requirements on maximum allowable SWL emitted from the PA system and noise monitoring specified in the contract documents, the future event organizers will be made aware of this operational constraint in organizing outdoor activities.

The calculated maximum allowable SWLs for the fixed plant noise sources that have been adopted in the assessment are summarised in Table 5.11.

Table 5.11 Maximum Allowable Sound Power Level of Fixed Plant Noise Sources

Item	Location	Maximum Allowable SWL per unit, dB(A)	Quantity ^(a)	Total SWL, dB(A) ^(a)
Chilled Water Pumps	West louvre of chilled water pump room on the roof of Arbuthnot Wing	72	3/2	77/75
Condenser Water Pumps	West louvre of condenser water pump room on the roof of Arbuthnot Wing	72	3/2	77/75
Cooling Tower	Cooling towers on the roof of Arbuthnot Wing	80	3/2	85/83
Chiller	East louvre of chiller room on the roof of Arbuthnot Wing	75	3/2	80/78
Genset ^(b)	G/F plant room of Old Bailey Wing	84	1/-	84/-
Transformer	West louvre of transformer room of Ablution Block	75	2/2	78/78
Transformer	South louvre of transformer room of Ablution Block	75	4/4	81/81
Fan	West louvre of Police Headquarters at lower courtyard	85	1/1	85/85
Fan	East louvre of Police Headquarters at lower courtyard	85	1/1	85/85
PA system ^(b)^(c)	Lower courtyard	91	4/-	97/-
PA system ^(b)^(c)	Upper courtyard	86	2/-	89/-
Notes: (a) 3/2 indicates the quantity of the plant items for day-time and evening time period, and night-time period, respectively. (b) Genset and PA system will only be operated during the day-time and evening time period. (c) The design of the PA system may be different for individual event and details are not available at this stage. The Project Proponent has committed that the design of the PA system for each event shall comply with all mandatory noise control requirements. With regard to this, assumptions were made on the nos. of speaker clusters for the purpose of the assessment. The maximum allowable SWL for each speaker at the lower courtyard would be 91dB(A); whereas that at the upper courtyard is 86dB(A).

5.9 Mitigation Measures

5.9.1 Construction Phase

In view of the predicted noise exceedances during the construction of the Project, the following mitigation measures have been considered:

· Good construction site practice;

· Use of quiet PME;

· Adoption of movable noise barriers;

· Use of noise insulation sheet; and

· Scheduling of PME/construction activities.

Good Construction Site Practices

Good construction site practices and noise management can considerably reduce the potential noise impact of the construction activities on nearby NSRs.  The noise benefits of these practices can vary according to specific site conditions and operations.  Since the effect of the good construction site practices could not be quantified, the mitigated noise levels calculated in the subsequent sections have not taken account of this effect.  The following site practices should be followed during the construction of the Project:

· Only well-maintained plant will be operated on-site and plant will be serviced regularly during the construction phase;

· Silencers or mufflers on construction equipment will be utilised and will be properly maintained during the construction phase;

· Mobile plant, if any, will be sited as far away from NSRs as possible;

· Machines and plant (such as trucks) that may be in intermittent use will be shut down between work periods or will be throttled down to a minimum;

· Plant known to emit noise strongly in one direction will, wherever possible, be orientated so that the noise is directed away from the nearby NSRs; and

· Material stockpiles and other structures will be effectively utilised, wherever practicable, in screening noise from on-site construction activities.

Use of Quiet PME

The use of quiet PME is considered to be a practicable means to mitigate the construction noise impact.  Quiet plant is defined as a PME having actual SWL lower than the value specified in the GW-TM.  Quiet PME that have been adopted in the assessment are summarised in Table 5.12.

Table 5.12 Sound Power Level of Quiet PME

PME Item	BS 5228^(a)/ EPD QPME Reference^(b)	Sound Power Level, dB(A)
Excavator	BS D3/97	105
Concrete pump	BS D6/36	106
Vibratory poker	BS D6/40	98
Mobile crane	BS D7/114	101
Breaker	BS D8/12	106
Dump truck	BS D9/39	103
Lorry	EPD QPME	105
Drill rig	EPD QPME	110
Grout mixer	EPD QPME	90
Grout pump	EPD QPME	105
Notes: (a) British Standard BS 5228:2009, Part 1 - Noise and Vibration Control on Construction and Open Sites (b) “Sound power levels of other commonly used PME” prepared by the Noise Control Authority (http://www.epd.gov.hk/epd/english/application_for_licences/guidance/files/OtherSWLe.pdf )

Adoption of Movable Noise Barriers

The use of noise barriers will be an effective means to mitigate the noise impact arising from the construction works, particularly for low-rise NSRs.  Movable noise barriers of 3m in height with skid footing should be used and located within a few metres of stationary plant and mobile plant such that the line of sight to the NSR is blocked by the barriers.  The length of the barrier should be at least five times greater than its height. It is anticipated that the major noise source of all PMEs, including movable and large PMEs, will be located at a level lower than the top of the proposed movable barriers, and therefore these barriers could produce at least a 5 dB(A) noise reduction for mobile plant such as excavator as well as large scale plant such as a crane.  With reference to A Practical Guide for the Reduction of Noise from Construction Works, the noise barrier material should have a superficial surface density of at least 7 kg m^-2 and have no openings or gaps.

Use of Noise Insulating Sheet

Noise insulating sheet would be adopted for PME such as drill rig. The noise insulating sheet should be deployed such that there would be no opening or gaps on the joints. With reference to the approved EIA Report for West Island Line (WIL) (Register No.: AEIAR-126/2008 approved on 23 Dec 2008) and MTRC Contract C4420 Tsim Sha Tsui Modification Noise Assessment Report for Variation of Environmental Permit (July 2003) and the technical data from the manufacturer of the noise insulating sheet, a reduction of over 10 dB(A) could be achieved with the use of the noise insulating sheet. For a conservative assessment, a noise reduction of 10 dB(A) for the PME with noise insulating sheet deployed was assumed in this assessment.

Scheduling of PME/Construction Activities

To further alleviate the construction noise impacts, some construction activities will be operated in sequence rather than simultaneously within the respective works areas, ie only Group A, Group B, Group C or Group D of PMEs should be operated at any time (see Annex B4).

The above mitigation measures have been vetted and confirmed by the CPS Ltd and its Engineering Consultants as being practicable in completing the works within the scheduled timeframe. It is considered practical to specify the quiet PME and noise mitigation measures described in Section 5.9.1 in the contract document to mitigate the construction noise impact.

With the implementation of the good construction site practices, use of quiet PME and movable noise barriers and scheduling of PME/construction activities (as shown in Annex B4), the mitigated noise levels due to the construction of the Project and concurrent projects were calculated at the representative NSRs with results summarised in Tables 5.13. Summaries of predicted mitigated noise levels and detailed calculations are presented in Annex B4.

Table 5.13 Predicted Construction Noise Levels during Day-time Period (With Mitigation)

NSR	Description	Predicted Construction Noise Levels^(a), Leq, 30 min dB(A)
N1	Amber Lodge	67 - 71
N2	Ho Fook Building	67 - 72
N3	Old Bailey Street Police Married Quarters	69 - 72
N4	Cambridge Villa	71 - 73
N5	Chancery House	73 – 75
N6	Chancery Mansion	73 - 75
Note: (a) All predicted noise levels were corrected with 3dB(A) for façade reflection.

The results indicate that with the adoption of the recommended mitigation measures, no exceedance of the EIAO-TM noise criteria during the construction phase is anticipated at NSRs.  No further mitigation will therefore be required.

5.9.2 Operation Phase

Although no adverse noise impact is expected due to the operation of fixed plant items, it is still recommended that the following measures be implemented as far as practicable to minimise the potential impact:

· Choose quieter equipment;

· Include noise levels specification when ordering new plant items;

· Locate fixed plant items or noise emission points away from the NSRs as far as practicable;

· Locate noisy machines in completely enclosed plant rooms or buildings with suitable and practicable noise remedies; and

· Develop and implement a regularly scheduled plant maintenance programme so that plant items are properly operated and serviced. The programme should be implemented by properly trained personnel.

Noise Emissions from Events at the Courtyards and the Use of Public Address (PA) System

· good management practices shall be in place, including noise monitoring, setting up a complaint hotline, and distributing advance notice to nearby NSRs. It is recommended that good management practices be implemented during both rehearsals and shows;

· in any event that an outdoor event is expected, the event organizer is required to undertake noise monitoring at least at one of the affected NSR. One set of L_eq(30min) noise measurements before and during the event should be taken;

· as a fallback option, should non-compliance of the relevant noise criteria at the NSRs be identified for the event, immediate mitigation measures (such as turning down/off of music volume) should be implemented; and

· The requirements of not exceeding the total sound power level (as given in Section 5.8) and noise monitoring for each independent event are specified in the contract document.

5.10 Cumulative Impact

One potential concurrent construction work is identified within the Study Area. The former Police Married Quarters on Hollywood Road at about 250m to the west of the Project Site will be revitalised and brought into operation in early 2014. Details of the revitalised work are not available yet but the works are anticipated to be relatively small scale. Given that the former Police Married Quarters site is located about 250m away from the Project Site and separated by dense buildings, no cumulative noise impact is expected during the construction and operation phases.

5.11 Residual Impact

With the implementation of the recommended noise mitigation measures, the predicted noise levels due to the construction of the Project would comply with the EIAO-TM day-time noise criterion.  No residual impact is anticipated.

The assessment results indicated that residual fixed plant noise impacts due to the operation of the Project would not be expected.

5.12 Environmental Monitoring and Audit

Noise monitoring is recommended during the construction phase to ensure compliance with the noise criterion at the NSRs. Weekly noise monitoring will be undertaken at the representative NSRs N2 Ho Fook Building and N5 Chancery House. Monthly site audits will be conducted to ensure that the recommended mitigation measures are properly implemented during the construction stage.

With the implementation of the recommended mitigation measures, no adverse impact is expected due to the operation of the fixed plant items. Monitoring will be required for outdoor events only and will be specified in the contract document for the event organisers for implementation..

5.13 Conclusions

Owing to the close proximity of some of the NSRs to the works area of the Project Site, mitigation measures are required to be implemented to mitigate the construction noise impacts. Practicable mitigation measures, including good construction site practices, use of quiet PME, movable noise barriers and scheduling of PME/construction activities, are recommended. With the implementation of the recommended mitigation measures, the mitigated construction noise levels at the representative NSRs will comply with the construction noise criterion of 75 dB(A) throughout the construction period. Noise monitoring during the construction stage is recommended to ensure compliance with the relevant noise criteria.

The predicted operational noise levels at the representative NSRs are expected to comply with the day-time and evening-time criteria based on the assessment using a set of specified maximum SWLs for the fixed plant to be installed for the Project. Attenuation measures, if required, will be provided to the fixed plant for achieving the guaranteed noise levels during the detailed design stage. Noise monitoring during the operational phase of the revitalised CPS should follow the contractual requirements as necessary.

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([1]) British Standard “Noise and Vibration Control on Construction and Open Sites – Part I”, BS 5228: Part I

([2]) “Sound power levels of other commonly used PME” prepared by the Noise Control Authority (http://www.epd.gov.hk/epd/english/application_for_licences/guidance/files/OtherSWLe.pdf )