5                    NOISE IMPACT ASSESSMENT

 

5.1.1          This section presents the key findings of the assessment of potential noise impacts arising from the construction and operational phases of the proposed crematorium and demolition of the existing crematorium. The primary objectives are:

 

Ÿ             to determine the assessment area;

Ÿ             to describe the existing noise environment in the vicinity of the proposed crematorium;

Ÿ             to identify existing and planned noise sensitive receivers (NSRs) that will be potentially affected by the noise emission of the proposed crematorium;

Ÿ             to present an emission inventory of noise sources;

Ÿ             to describe the assessment methodology employed to predict construction and operational noise impacts, and the predicted noise impacts;

Ÿ             to evaluate the predicted noise impacts against recognized criteria; and

Ÿ             to recommend noise mitigation measures where necessary to satisfy the acceptable noise levels.

 

5.2              Study Area

 

Description of the Noise Environment

 

5.2.1          Major land uses close to the proposed development are mainly residential, recreational and educational. The existing noise climate in the Study Area is dominated mostly by the community activities and traffic of Po Kong Village Road. To the northwest of the project site are school complex developments (i.e. Po Kong Village Road School Village and others). To the south are high-rise residential developments (i.e. Grand View Garden and Fu Shan Estate). To the east is the hillside of Nam Shan Mei whilst the northern side is the Diamond Hill Urn Crematory.

 

Determination of Assessment Area

 

5.2.2          As defined in Clause 3.6.5.2(i) of the Study Brief, the Assessment Area for the noise impact assessment included all areas within 300m from the boundary of the proposed crematorium. Generally, noise at distances beyond 300m from a fixed noise source would not be significant. The area of concern has covered a majority of residential uses and educational institutions in the vicinity of the proposed crematorium, and noise impact on this area can reflect the worst case scenario arising from the noise of construction and operational phases of the proposed crematorium.

 

Identification of Representative Noise Sensitive Receivers

 

5.2.3          Site surveys and desktop study of government survey maps, the latest Outline Zoning Plan (as shown in Figure 8.1) and Outline Development Plans were conducted to check the existing and planned/ committed land uses within 300 m from the boundary of the Study Area. Representative Noise Sensitive Receivers (RNSRs) defined by the EIAO-TM and NCO were selected to represent both the existing and future land uses which are potentially affected by the implementation of the Project.

 

5.2.4          The RNSRs identified for the construction/ demolition and operational noise assessment for different stages of the Project are tabulated in Table 5.1. Geographical locations of these RNSRs are shown in Figure 5.1.

 

Table 5.1       Details of the Representative Noise Sensitive Receivers

 

Representative NSRs		Status (1), (2)	No. of Storey	Ground Level, mPD	Horizontal Distance to Notional Source, m		Uses
					Phase I Site	Phase II Site
SR1	The Salvation Army William Booth Secondary School	E	6	84.1	210	170	School
SR2	Po Leung Kuk No1. W. H. Cheung College	E	6	87.4	180	170	School
SR3	(New school under construction)	F	8	85.6	170	160	School
SR4	Po Leung Kuk Grandmont Primary School	E	8	85.6	210	220	School
SR5	St. Patrick Catholic Primary School	E	8	85.6	280	290	School
SR6	Staff Quarter for Diamond Hill Crematorium	E	2	60.4	75	110	Residential
SR7	Fu Yan Hse	E	20	61	180	260	Residential
SR8	Fu Shun Hse	E	22	61	220	300	Residential
SR9	Grand View Garden (Blk 1)	E	39	39.7	280	--(3),	Residential

Note:       (1) Status “E” denotes as the existing sensitive receivers

                (2) Status “F” denotes as the future sensitive receivers

(3) “--“  denotes as RNSRs with horizontal distance to the notional source more than 300 metres.

 

5.3              Construction and Demolition Noise Assessment

 

Methodology of Assessment and Assumptions

 

5.3.1          The construction noise assessment was conducted based on standard acoustic principles and the methodology stated in the GW-TM and Sections 5 of Annex 13 of the EIAO-TM. The assessment also made reference to the BS5228:Part 1:1997 Noise Control on Construction and Open Sites (hereafter stated as BS5228). In general, the assessment methodology was conducted as follows:

 

(i)          Identification of the nearest RNSRs to the work site;

 

(ii)        Identification of the items and number of PMEs likely to be used during the course of project implementation;

 

(iii)       Determination of the total Sound Power Level (SWL) of the PMEs;

 

(iv)      Determination of distance attenuation, barrier corrections and reflection corrections to the RNSRs from notional source position of each construction phase;

 

(v)        Calculation of the Predicted Noise Level (PNL) at the respective RNSRs; and

 

(vi)      Comparison of the PNL with the corresponding noise criteria.

 

Potential Sources of Impact and Emission Inventory

 

5.3.2          To indicate the potential noise impact at different stages of the project, the emission inventories of the construction noise sources and their corresponding construction/ demolition noise levels are suggested according to the programme of works shown in Figure 2.7. The on-site project activities which would cause potential construction/ demolition noise impacts include:

 

Phase I works (southern part of the construction site)

 

Ÿ             Site formation (including demolition of the minor facilities, eg. demolition of the existing CLP secondary station, toilets, etc., as addressed in Section 2.6.1) and

Ÿ             Construction of building and cremators

 

Phase II works (northern part of the construction site)

 

Ÿ             Demolition of the existing buildings and cremators;

Ÿ             Site formation and

Ÿ             Construction of building

 

Works under different Phases will be carried out in different period of time, i.e. demolition work of Phase II will be carried out after completion of the Phase I construction works.  Besides, construction activities for each type of work under a particular Work Phase are scheduled to be carried out in series, e.g. demolition works and site formation works under Phase I will not be conducted concurrently , as confirmed by the project proponent.

 

5.3.3          No piling works is expected during the construction and demolition stages of the crematorium. The inventories of the PMEs expected to be used during each stage of construction/ demolition works are summarised in Appendix B1. The project proponent has advised that these equipment represent a realistic and practicable approach to meet the construction / demolition programme. It should be noted that they are the assumed inventories of the most likely used PMEs.

 

5.3.4          The assessment was undertaken on the basis of the assumption that all construction equipment will be located on a notional noise source point for each phase of works and to be operating simultaneously to simulate the worst scenario.

 

Assessment Results

 

5.3.5          The unmitigated PNLs at the identified RNSRs at each stage are summarised in Table 5.2. Detailed calculations are shown in Appendix B2.

 

Table 5.2       Predicted (Unmitigated) Noise Levels of Phase I and II Construction Works

 

RNSR	Predicted (Unmitigated) Construction Noise Level, dB(A)					Daytime Noise Standard (EIAO-TM), dB(A)
	Phase I		Phase II
	Site Formation	Construction of Building and/ or Cremators	Demolition	Site Formation	Construction of Building and/ or Cremators
SR1	69	64	72	70	66	70
SR2	70	65	72	70	66	70
SR3	75	71	78	76	71	70
SR4	74	69	75	73	68	70
SR5	71	66	73	71	66	70
SR6	82	78	81	79	74	75
SR7	75	70	74	72	67	75
SR8	73	68	72	70	66	75
SR9	71	66	--	--	--	75

Notes:     (1) Bolded figures in the shaded cells denote exceedance of the daytime noise standards in EIAO-TM.

 

Phase I Works

 

5.3.6          RNSRs, except SR1, SR2, SR7, SR8 and SR9, are expected to be subject to construction noise levels above the daytime noise standards contributed from the Phase I site. Mitigation measures are thus required to alleviate the noise impacts for these stages of works.

 

Phase II Works

 

5.3.7            Due to the close proximity, it is expected that SR1 to SR6 would be subject to noise levels above the daytime noise standards during the demolition of the existing crematorium of the Phase II site. In addition, similar to the noise impacts in Phase I works, SR3, SR4, SR5 and SR6 are expected to be affected by the Construction works of Building and/ or Cremators and site formation works. Mitigation measures are thus also required to alleviate the noise impacts for these stages of Phase II works.

 

Proposed Construction/Demolition Noise Mitigation Measures

 

5.3.8          As the PNLs showed that both Phases I and II works would give rise to adverse daytime noise impacts to some of the RNSRs, practicable mitigation measures to alleviate noise impact are required and detailed below.

 

Selection of Quiet Plant

 

5.3.9          Quiet plant is defined as PME with a sound power level lower than that specified in GW-TM. For the sake of flexible construction/ demolition arrangement to suit the actual site situation, it is not recommended to restrict specific types of quiet equipment to confine the Contractor’s selections at this preliminary stage. For easy reference, however, examples of quiet plant can be referred to those listed in British Standard BS5228 which are also listed in Table 5.3 below. Various items of these quiet plants are available in Hong Kong. However, the Noise Control Authority, when processing a Construction Noise Permit (CNP) application, would refer to the noise levels stipulated in the relevant TM unless the noise emission of the claimed quiet plant can be validated by certificate or demonstration.

 

Table 5.3       Examples of Quiet PME

 

PME	BS 5228 Reference no.	SWL/unit, dB(A)
Air compressor	C.7-43	102
Breaker, excavator mounted	C.2-4	119
Breaker, hand-held	C.2-10	110
Bulldozer	C.3-65	111
Concrete pump	C.6-36	106
Crane, mobile	C.7-110	106
Excavator	C.3-97	105
Poker, vibratory, hand-held	C.6-32	100

 

5.3.10      Since the use of quiet plant is generally considered to be one of the most effective ways of alleviating construction/ demolition noise, this control measure is recommended as the first level mitigation (Mitigation 1) for the construction/ demolition works.  Calculations of the construction noise levels for the quiet plant are shown in Appendix B2.

 

Use of Movable (Mobile) Barriers

 

5.3.11      Where practicable, movable (mobile) barriers can be used to screen NSRs from particular items of plant or noisy operations. Movable barriers of 3 to 5 m in height with a small cantilevered upper portion and skid footing can be located within a few metres from the stationary plant (e.g. generator, compressor, etc.) and within about 5 m for a mobile equipment (e.g. breaker, excavator, etc.), such that the line of sight to the NSRs is blocked by the barriers. It would be possible for the Contractor to provide purpose-built noise barriers or screens constructed of appropriate material with a minimum superficial density of 15 kg/m² located close to the operating equipment.

 

 

 

5.3.12      For those activities which still potentially affect the NSRs after applying the quiet plant, the use of movable (mobile) noise barriers for the construction equipment is recommended as the second level mitigation (Mitigation 2).  Calculations of the construction noise levels for the quiet plants with movable (mobile) noise barriers are shown in Appendix B2. Such mitigation should be applied to the site activities that are in close proximity to NSRs, specifically to SR3 (the new school), SR4 (Po Leung Kuk Grandmont Primary School) and SR6 (Staff Quarter for Diamond Hill Crematorium) during the site formation works of Phase I and II and demolition works in Phase II. For assessment purpose, the noise reduction of such barrier is assumed to be 5 dB(A) and an example of movable (mobile) noise barrier arrangement is illustrated in Figure B1 in Appendix B1.

 

Good Site Practice

 

5.3.13      Good site practice and noise management can be readily applied to achieve additional reductions in the construction noise emissions, which include:

 

Ÿ             only well-maintained plant should be operated on site and the plant should be regularly serviced during the construction works;

Ÿ             plant that is used intermittently, should be turned off or throttled down when not in active use;

Ÿ             plant that is known to emit noise strongly in one direction should be oriented to face away from NSRs;

Ÿ             silencers, mufflers and enclosures for plant should be used where possible and maintained adequately throughout the works;

Ÿ             where possible mobile plant should be sited away from NSRs; and

Ÿ             stockpiles of excavated materials and other structures such as site buildings should be used effectively to screen noise from the works.

 

5.3.14      Such noise reduction was not included in the noise assessment as it cannot be quantified.  Nevertheless, these measures would help to achieve further noise reduction.

 

Residual Impacts

 

5.3.15      The PNLs with the implementation of the proposed mitigation measures for different stages of the Project are summarized in Tables 5.4 and 5.5. The results show that :

 

(i)          the noise impacts due to the activities of the construction of building and/ or cremators in both Phase I and II sites can be mitigated to the noise standards by using quiet equipment and;

 

(ii)        the noise impact due to the demolition and site formation works of the Phase I and Phase II can be mitigated to the noise standards by using quiet equipment as well as applying movable noise barriers, specifically towards SR3, SR4 and SR6.

 

(iii)       It should be noted that the noise standard for educational institutions is lower during examination periods (i.e. 65 dB(A)). The contractor should therefore minimize construction noise exposure to SR1 to SR5 (i.e. the northwest side of the construction site), especially during examination periods as far as possible. In addition, the contractor should liaise with the schools and the Hong Kong Examinations and Assessment Authority to ascertain the dates and times of examination periods during the course of the construction/ demolition works.  It is suggested that the Contractor should hold regular liaision meeting with the schools regarding the impact of construction noise during the construction periods.  Programme of the on-site works should hence be well programmed such that the noisier construction activities would not be coincided with the examination periods of the schools. With implementation of the above suggested measures, no residual impact would be expected. 

 

Table 5.4       Predicted (Mitigated) Noise Levels of Phase I Works

 

RNSR/ Mitigation Measures	Predicted (Mitigated) Construction Noise Level, dB(A)			Daytime Noise Standard (EIAO-TM), dB(A)
	Site Formation		Construction of Building and/ or Cremators
	Mitigation 1	Mitigation 1 & 2	Mitigation 1
SR1	65	--	58	70
SR2	66	--	60	70
SR3	72	67	65	70
SR4	70	--	63	70
SR5	67	--	61	70
SR6	79	75	72	75
SR7	71	--	65	75
SR8	69	--	63	75
SR9	67	--	61	75

Notes:     (1) Bolded figures in the shaded cells denote exceedance of EIAO-TM daytime noise standards.

                (2) “Mitigation 1” = use of quiet equipment only

(3) “Mitigation 1 & 2” = use of quiet equipment and movable noise barrier.

 

Table 5.5       Predicted (Mitigated) Noise Levels of Phase II Works

 

RNSR/ Mitigation Measures	Predicted (Mitigated) Construction Noise Level, dB(A)					Daytime Noise Standard (EIAO-TM), dB(A)
	Demolition		Site Formation		Construction of Building and/ or Cremators
	Mitigation 1	Mitigation 1 & 2	Mitigation 1	Mitigation 1 & 2	Mitigation 1
SR1	69	--	67	--	60	70
SR2	69	--	67	--	60	70
SR3	74	70	72	68	66	70
SR4	71	67	69	--	63	70
SR5	69	--	67	--	61	70
SR6	77	73	75	--	69	75
SR7	70	--	68	--	62	75
SR8	69	--	67	--	60	75

Notes:     (1) Bolded figures in the shaded cells denote exceedance of EIAO-TM daytime noise standards.

                (2) “Mitigation 1” = use of quiet equipment only

(3) “Mitigation 1 & 2” = use of quiet equipment and movable noise barrier.

 

 

5.4              Operation Noise Assessment

 

Methodology of Assessment and Assumptions

 

5.4.1          Noise from future fixed plants associated with the proposed crematorium were assessed and presented in this section. Noise prediction was based on the assumed plant inventories and utilization schedule for the worst-case scenario. The noise impact assessment was undertaken according to the standard acoustic principle with reference to IND-TM.

 

Potential Fixed-noise Sources

 

5.4.2          According to the information given by the project proponent on the electrical and mechanical provisions of the Crematorium (including Phase I and Phase II development), fixed-noise sources potentially affecting the nearby NSRs during the operation stage include condensers of split air-conditioning units, radiators for cremators, general exhaust air fans and exhaust fans for the air pollution control system of the cremators as summarised in Appendix B3. The sound power levels adopted in the assessment were given and confirmed by the engineer of the project proponent. Requirements of the  sound power levels of these equipment will be incorporated into the tender specification.

 

5.4.3          All these systems are expected to be operated during the daytime period, i.e. within 0700 to 2300 hour daily. As such, the potential operation noise impact for the daytime is assessed.

5.4.4          The prevailing daytime noise levels as measured on 1- 2August 2003 in the proximity of the representative NSRs and the area sensitivity ratings (ASR) are tabulated in Table 5.6.

 

Table 5.6       Prevailing Daytime Noise Levels and ASR of the Representative NSRs

 

 

Note:

 

(1)  The suggested classifications are determined based on the the following factors as stipulated in IND-TM:

(i)           Type of area within which the NSR is located - All the above representative NSRs are located in a residential area at which majority of the uses are institutional and high-rise residential developments.

(ii)         Influencing factor - All the above representative NSRs are located in close proximity to Po Kong Village Road, which is classified as a district distributor. According to the Annual Traffic Census 2002 issued by the Transport Department on June 2003, the annual average daily traffic (AADT) of Po Kong Village Road (from Tsz Wan Sha Road to Lung Cheung Road) in year 2001 is 32,270. This road is thus considered as an influencing factor which directly or indirectly affects the representative NSRs as recommended under the IND-TM.

Under such circumstances, the Area Sensitivity Ratings (ASR) for these representative NSRs are hence classified as “B” hereby for the conservative assessment. In any event, the ASR assumed here is for indicative assessment only.

 

(2)  Summary of the measured prevailing noise levels at each representative NSR conducted by the Consultant are tabulated in Table B3-ab of Appendix B3.

 

5.4.5          Since the prevailing noise levels of the representative NSRs are higher than or equal to the “ANL -5dB(A)” (i.e. 60dB(A) for area sensitivity rating “B”), the daytime noise limit of 60dB(A) as discussed in Subsection 3.3.3  is adopted as the noise criteria for compliance check.

 

5.4.6          To simulate the worst scenario, the following conservative assumptions were made for the operation noise impact assessment:

 

Ÿ             the fixed-noise sources to be located at the outdoor area of the concerned premises

Ÿ             the fixed-noise sources to be located at the respective notional source positions[a] of the Phase I and Phase II sites

Ÿ             all the fixed-noise sources to be operated simultaneously during the operation period

Ÿ             tonality correction of 6dB(A) was applied to the noise levels of all the fixed-noise sources[b].

 

Assessment Results

 

5.4.7          The predicted operation noise levels at the representative NSRs are summarised in Table 5.7 below. Detailed noise calculation is provided in Appendix B3 and the quantitative assessment of the façade noise levels  at various representative floor levels of the RNSRs are conducted. All the predicted noise levels at these RNSRs are found to be within the noise limit of EIAO-TM. As such, it is expected that there would be no significant noise impacts on the nearby NSRs when the specified noise levels and the quantities of the fixed plants are strictly followed in the detailed design.  In general, noise from the operation of the concerned fixed-noise sources can be further reduced by locating them as far as practical from the NSRs, and/ or by orientating the noise emission points  (e.g. discharge points of ventilation, etc.) away from the NSRs, and/ or by application of silencers, acoustic barriers or enclosures to the concerned equipment.

 

Table 5.7       Predicted Noise Impacts Contributed from the Operation of the Crematorium

 

RNSR	Location	Predicted Operation Noise Level LAeq(30min), dB(A)			Daytime Noise Standard - ASR “B” (EIAO-TM) LAeq(30min), dB(A)
		Representative Floor Levels(1)
		High Level	Mid Level	Low Level
SR1	The Salvation Army William Booth Secondary School	52	52	52	60
SR2	Po Leung Kuk No1. W. H. Cheung College	52	52	52
SR3	(New school under construction)	53	53	53
SR4	Po Leung Kuk Grandmont Primary School	50	50	51
SR5	St. Patrick Catholic Primary School	48	48	48
SR6	Staff Quarter for Diamond Hill Crematorium	58	58	58
SR7	Fu Yan Hse	51	51	51
SR8	Fu Shun Hse	49	49	49
SR9	Grand View Garden (Blk 1)	45	45	45

Note:

(1)     The representative floor levels of each RNSR for the assessment are detailed in Appendix B3.

 

 

 

5.4.8          As the recorded prevailing daytime noise levels of each RNSR are much higher than the respective predicted operation noise levels (i.e. with differences ranging from 2 to 20 dB), the future noise levels at these RNSRs are not expected to have much deviation from the existing noise levels for the daytime operation of the new crematorium.

 

Transitional Impacts (Testing and Commissioning of New Cremators)

 

5.4.9          During testing and commissioning of the new cremators in Phase I site, the existing crematorium in Phase II site would be still operative for the public use. To minimize the potential environmental impacts at this transitional stage, special operation arrangement would be implemented by FEHD such that no more than six cremators, including both the existing and new cremators, and the associated air pollution control system are operated simultaneously. Under such arrangement, the potential transitional noise level caused by the trail run of the new cremators and operation of the existing units would be similar to, if not less than, the full operation of the new crematorium of the Phase I and Phase II. As such, no adverse noise impact is expected during the transitional stage.

 

5.5              Summary

 

Construction and Demolition Noise

 

5.5.1          The use of powered mechanical equipment during the construction/ demolition activities of Phase I and II works of the Project is expected to create potential construction noise nuisance to the nearby residential premises and schools. Practical mitigation measures are available to reduce the construction noise levels to acceptable levels. The recommended mitigation measures include the use of quiet plant, the use of movable noise barriers and good site practices. The contractor should also cease the noisy works as far as possible especially during examination periods of the nearby schools to further reduce the noise impact to them. When the contractor implements the recommended mitigation measures with good care on their working conditions, the construction noise will be much reduced during the construction/ demolition stage of works. In addition, regular noise monitoring is recommended at the selected NSRs in the EM&A manual during the construction period to check the compliance of the statutory noise requirements. Details of the monitoring requirements are addressed in the EM&A manual.

 

Operation Noise

 

5.5.2          No adverse noise impact on the nearby NSRs by the given potential fixed noise sources, including mainly the condensers of split air-conditioning units, radiators for cremators, general exhaust air fans and exhaust fan for the air pollution control system of the cremators in the crematorium, would likely exist.  Noise levels of the concerned equipment can be further reduced by locating them as far as practical from the NSRs, and/ or by orientating the noise emission points away from the NSRs, and/ or by application of silencers, acoustic barriers or enclosures to the concerned equipment.