This section presents the assessment of potential noise impacts associated with the construction and operation phases of the Project, which has been conducted in accordance with the criteria and guidelines as stated in Annex 5 and Annex 13 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) as well as the requirements given in Clause 3.4.4 and Appendix C of the EIA Study Brief (ESB-289/2015).
Control over the generation of construction noise from Designated Projects (DPs) under Environmental Impact Assessment Ordinance (EIAO) in Hong Kong is governed by the EIAO and the Noise Control Ordinance (NCO). The NCO is to provide statutory controls for carrying out construction work using Powered Mechanical Equipment (PME) and prescribed construction works during the restricted hours. The noise standards for daytime construction activities of DPs are in accordance with Table 1B, Annex 5 of Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM). The Technical Memoranda (TMs) applicable to the control of noise from construction activities of the proposed construction works of the Project are:
● TM on Environmental Impact Assessment Process (EIAO-TM)
● TM on Noise from Construction Work other than Percussive Piling (GW-TM)
These TMs prescribe the maximum permitted noise levels for the use of PME and certain construction activities and processes, according to the type of equipment or activity, the perceived noise climate of the area, and the working hours of equipment operation and usage.
The works area of this project will fall outside the Designated Areas. Therefore, the TM on Noise from Construction Work in Designated Areas is not applicable to the Project.
According to the proposed construction methodology, percussive piling is not required for the Project. Therefore, the TM on Noise from Percussive Piling is not applicable to the Project.
Noise impacts arising from general construction activities other than percussive piling during the daytime period (0700 – 1900 hours of any day not being a Sunday or general holiday) would be assessed against the noise standards tabulated in Table 4.1 below.
Table 4.1: Noise Standards for Daytime Construction Activities
|
Noise Sensitive Use |
0700 to 1900 hours on any day not being a Sunday or general holiday, Leq(30 mins), dB(A) |
|
All domestic premises including temporary housing accommodation |
75 |
|
Hotels and hostel |
|
|
Education institutions including kindergarten, nurseries and all others where unaided voice communication is required |
70 65 during examination |
Source: EIAO-TM, Annex 5 Table 1B – Noise Standard for Daytime Construction Activities
Notes:
(i) The above noise standards apply to uses which rely on openable windows for ventilation.
(ii) The above standards shall be viewed as the maximum permissible noise levels assessed at 1m from the external facade.
Noise impacts arising from general construction activities (excluding percussive pilling) conducted during the restricted hours (1900 to 0700 hours on any day and anytime on Sunday or general holiday) and percussive pilling during anytime are governed by the NCO.
For carrying out of any general construction activities involving the use of any PME within restricted hours, a Construction Noise Permit (CNP) is required from the Noise Control Authority under the NCO. The noise criteria and the assessment procedures for the issuing a CNP are specified in the GW-TM under the NCO.
Regardless of any description or assessment made in this section, in assessing a filed application for a CNP, the Noise Control Authority will be guided by the relevant TMs. The Noise Control Authority will consider all the factors affecting their decision taking contemporary situations/ conditions into account. Nothing in this Report shall pre-empt the Noise Control Authority in making their decisions, and there is no guarantee that a CNP will be issued. If a CNP is to be issued, the Noise Control Authority may include any conditions they consider appropriate and such conditions are to be followed while the works covered by the CNP are being carried out. Failing to do so may lead to cancellation of the permit and prosecution action under the NCO.
According to the construction programme, the proposed construction works would be carried out during non-restricted hours, i.e., 0700-1900 hours on any day not being a Sunday or general holiday. In case of any construction activities during restricted hours, it is the Contractor’s responsibility to ensure compliance with the NCO and the relevant TMs. The Contractor will be required to submit CNP application to the Noise Control Authority and abide by any conditions stated in the CNP, should any be issued.
For fixed noise sources impact assessment, the Acceptable Noise Levels (ANLs) for the Noise Sensitive Receivers (NSRs) are determined with consideration of the Area Sensitivity Rating (ASR) which is defined in the Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites (IND-TM) issued under the NCO.
The ASR depends on the type of area and the degree of impact that Influencing Factors (IFs) have on the NSRs as illustrated in Table 4.2 below. Industrial area, major road or the area within the boundary of Hong Kong International Airport shall be considered to be an IF. Regardless of the ASR adopted in the fixed noise sources impact assessment, the Noise Control Authority will assess the fixed noise sources and/ or take enforcement action, if necessary, based on the NCO, the relevant TMs and the contemporary conditions/ situations.
Table 4.2: Area Sensitivity Rating
|
Type of Area Containing NSR |
Degree to which NSR is affected by IF |
||
|
Not
Affected(c) |
Indirectly
Affected(d) |
Directly
Affected(e) |
|
|
(i) Rural area, including country parks(a) or village type developments |
A |
B |
B |
|
(ii) Low density residential area consisting of low-rise or isolated high-rise developments |
A |
B |
C |
|
(iii) Urban area(b) |
B |
C |
C |
|
(iv) Area other than those above |
B |
B |
C |
Source:
IND-TM, Table 1 – Area Sensitivity Rating
Definitions:
(a) “Country park” means an area that is designated as a country park pursuant
to section 14 of the Country Parks Ordinance.
(b) “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.
(c) “Not Affected” means that the NSR is at such a location that noise
generated by the IF is not noticeable at the NSR.
(d) “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.
(e) “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.
Fixed noise is controlled under the NCO and shall comply with the ANLs laid down in the Table 2 of the IND-TM. For a given ASR, the ANL, in dB(A), is given in Table 4.3 below.
Table 4.3: Acceptable Noise Level for Fixed Noise Sources
|
Time Period |
Area Sensitivity Rating |
||
|
A |
B |
C |
|
|
Day-time (0700 to 1900 hours) |
60 |
65 |
70 |
|
Evening (1900 to 2300 hours) |
|||
|
Night-time (2300 to 0700 hours) |
50 |
55 |
60 |
Source:
IND-TM, Table 2 - Acceptable Noise Levels
Note: (i) The above standards apply to uses
which rely on opened windows for ventilation.
(ii) The above standards should be viewed as the maximum permissible noise levels assessed at 1m from the external facade.
As stipulated in Annex 5 of the EIAO-TM, the noise standards for the planning fixed noise source are (a) 5 dB(A) below the appropriate ANL as stipulated in the IND-TM, or (b) the prevailing background noise levels (for quiet area with level 5 dB(A) below the ANL).
Background noise measurements were carried out in Wo Shang Wai (WSW) for the Project “Hong Kong Section of Guangzhou-Shenzhen-Hong Kong Express Rail Link” (XRL) EIA (EIA Report Register No. AEIAR-143/2009). Given that the background noise levels measured in the approved XRL EIA Report were carried out before the commencement of the Project “Proposed Comprehensive Development at Wo Shang Wai, Yuen Long” (the WSW Development) and XRL construction works, the background noise levels measured for the XRL project, which is lower than the prevailing background noise level, have been adopted in this EIA study as a conservative approach.
The subject site is located in rural area with village type developments. According to Table 4.2, the ASR of the NSR shall be classified as “B” for the assessment point directly or indirectly affected by nearby major roads, namely San Tin Highway, Castle Peak Road and San Tam Road which are considered as IFs according to the IND-TM. The ASR of the NSR shall be classified as “A” for the assessment point not affected by the identified IFs.
According to the approved XRL EIA Report, background noise measurements were conducted at 2 locations in Wo Shang Wai (see Figure 4.2). Measurement location M2 located within the WSW development site which is less affected by the identified IFs, has a noise environment similar to that of the representative NSRs under this EIA study. Hence, the measurement results at M2 in the approved XRL EIA have been adopted for determining the operation noise assessment criteria for the planned fixed noise criteria in this EIA study, as illustrated in Table 4.4 below.
Table 4.4: Noise Criteria for the Planned Fixed Noise Sources
|
Measurement Location in XRL EIA |
Time Period |
Measured Noise Level, Leq(30mins), dB(A) |
Area Sensitivity Rating |
ANL-5, dB(A) |
Operation Noise Assessment Criteria Leq(30mins) dB(A) |
|
M1 (Wo Shang Wai) |
Day-time and Evening (1400-1800) |
68 |
B |
60 |
60 |
|
Night-time (2300-0200) |
62 |
50 |
50 |
||
|
M2 (Wo Shang Wai) |
Day-time and Evening (1400-1800) |
51 |
A |
55 |
51 |
|
Night-time (2300-0200) |
49 |
45 |
45 |
Source: EIA of Hong Kong Section of
Guangzhou-Shenzhen-Hong Kong Express Rail Link, Table 5.8 – Background Noise
Measurement Results
Bold figure denotes noise criteria adopted in this EIA Study.
The Project site is located within the WSW development site in Yuen Long District. The Assessment Area for the noise impact assessment should generally include areas within 300 m from the boundary of the Project and the works of the Project as shown in Figure 4.1.
The proposed interim Sewage Treatment Plant (STP) is located within the existing WSW development site surrounded by the area with residential uses. The background noise environment is dominated by the traffic on nearby San Tin Highway, Castle Peak Road and San Tam Road. Noise impact from nearby construction works at the WSW development site and the XRL site was observed during site visit on 3 and 17 May 2016.
NSRs have been identified in accordance with Annex 13 of the EIAO-TM within the 300m assessment area. The existing, planned and committed noise sensitive developments and relevant uses on the relevant Outline Zoning Plans, Development Permission Area Plans, Outline Development Plans, Layout Plans and other relevant published land use plans, including plans and drawings published by Lands Department and any land use and development applications approved by the Town Planning Board were also reviewed in the vicinity of the Project.
For the purpose of noise impact assessment, the first layer of NSRs located close to boundary of the Project have been selected as assessment points/ identified representative NSRs within the assessment area.
Locations of all representative NSRs during construction and operation phases are shown in Figure 4.1 and Figure 4.2, respectively, and summarised in Table 4.5. The photos of the existing NSRs are showed in Figure 4.3. All construction work for the Project will be completed before occupation of the WSW Development with residential uses. As such, no NSRs within the Wo Shang Wai development site are considered during the construction phase.
Table 4.5: Representative Noise Sensitive Receivers for Construction and Operation Phases
|
NSR ID |
Description |
Existing/Planned |
Use |
No. of Storeys |
Construction Phase |
Operation Phase |
|
NSR 1 |
House No. 7, Cherry Path, Palm Springs |
Existing |
Residential |
3 |
Yes |
Yes |
|
NSR 2 |
House No. 1, Narcissus Path, Palm Springs |
Existing |
Residential |
3 |
Yes |
Yes |
|
NSR 3 |
House No. 61, Narcissus Path, Palm Springs |
Existing |
Residential |
3 |
Yes |
Yes |
|
NSR 4 |
St Lorraine English Kindergarten |
Existing |
Educational Institute |
1 |
Yes |
Yes |
|
NSR 5 |
House No. 1, Ventura Avenue, Royal Palms |
Existing |
Residential |
3 |
Yes |
Yes |
|
NSR 6 |
House No. 1, Marin Avenue, Royal Palms |
Existing |
Residential |
3 |
Yes |
Yes |
|
NSR 7 |
House No. 202, Mai Po San Tsuen |
Existing |
Residential |
3 |
Yes |
Yes |
|
NSR 8 |
House in Wo Shang Wai Development Site |
Planned |
Residential |
2 |
No |
Yes |
|
NSR 9 |
House in Wo Shang Wai Development Site |
Planned |
Residential |
2 |
No |
Yes |
|
NSR 10 |
House in Wo Shang Wai Development Site |
Planned |
Residential |
2 |
No |
Yes |
Potential noise impact during construction phase will be mainly from the uses of PME. As mentioned in Section 2.7, major construction activities will broadly include basement excavation, foundation works, superstructure construction and laying of associated piping network. The piping network for connecting to the effluent reuse facilities will be laid in conjunction with other utilities of the WSW Development. PME likely to be used in this Project include excavators, cranes, lorries, and concrete pumps etc. The major construction works are localized in the small footprint of the proposed interim STP building (i.e. 225 m2).
Underground construction work is required for the basement level of proposed interim STP, which is expected to involve small-scale construction activities only. Use of drill and blast method for these works is not expected. Therefore, no potential ground-borne noise impact to the existing NSRs is anticipated.
Potential noise sources during construction phase include construction noise from the WSW development site. Given that the construction of XRL is expected to be completed in Q3 2018 (as mentioned in Section 2.9), no cumulative construction noise impact associated with XRL is anticipated.
Potential noise sources during operation phase include the operation of the proposed interim STP, the planned Electrical and Mechanical (E&M) building under the WSW development site, the existing Mai Po Ventilation Building (MPVB) and the existing STP at the nearby residential development Royal Palms, as shown in Figure 4.2.
The proposed interim STP will be situated closed to the planned residential buildings in WSW development site, and is expected to operate 24 hours a day. There will be one louver opening on the western façade of the proposed interim STP. During the operation phase, noise will be generated from fixed plants including screens, blowers, pumps and fans, etc. which are enclosed in the proposed interim STP building structure. Potential noise impact to the nearby NSRs (i.e. residential uses of the WSW Development) from the operation of the STP is anticipated.
Also associated with the operation of the proposed interim STP is the transportation of sludge by designated sewage tankers for off-site disposal. The collection and transportation of sludge is expected to involve two vehicles per day only during non-peak traffic hours of day-time and evening periods. The sludge collection and loading activities will be carried out underground at basement level and well shielded from the nearby NSRs. Thus, no significant potential noise impact from the delivery of sludge is expected.
The E&M buildings at the eastern part of the WSW development site will be in small scale. Plants of the E&M building will be entirely enclosed and confined. Therefore, noise impact from the E&M building is considered insignificant and will not be considered in this assessment.
The MPVB is located within the XRL site near the east boundary of the WSW development site, and is expected to operate 24 hours a day. The ventilation openings at four sides of the MPVB are expected to cause noise impacts.
An existing STP at Royal Palms is located at the south-east of the Project site, and is expected to operate 24 hours a day. The distance between the proposed interim STP to the existing STP is about 200m nd there is line-of-sight from the residential uses of the WSW development to the noise sources. Potential cumulative noise impact from the operation of the existing STP is also expected.
The proposed interim STP will be decommissioned when the WSW development is connected to the committed public sewer. The STP will only cease operation and the structure of the STP and its associated infrastructure will not be demolished. No PME would be used for the decommissioning work. As such, no noise impact is anticipated during decommissioning phase.
According to the requirement of Clause 2.1 of the Appendix C of the Study Brief (ESB-289/2015), the construction noise impact assessment should be conducted in accordance with methodology in paragraph 5.3 and 5.4 of Annex 13 of the EIAO-TM. The construction noise impact assessment is carried out based on standard acoustic principles and practices, following the methodology given in the Section 2 of the GW-TM.
Potential construction noise sources include the uses of plants and equipment for the construction of the proposed interim STP and associated piping network. Construction activities are expected to be carried out during non-restricted hours. The potential construction noise impacts shall be assessed against the noise standards stipulated in Table 1B, Annex 5 of the EIAO-TM.
As mentioned in Section 4.6.1, potential ground-borne noise impact is not anticipated, hence no ground-borne noise impact assessment is carried out in this EIA Study.
The major fixed noise sources identified during the operation phase include the proposed interim STP itself, the existing STP at Royal Palms and Mai Po Ventilation Building (MPVB).
According to Clause 3.3.1 in the Appendix C of the EIA Study Brief (ESB-289/2015), various operation modes including worst operation mode and other operation modes of the fixed noise source should be quantitatively assessed. However, in absence of detailed information and noise specification for the proposed interim STP, the maximum allowable noise emission levels at the opening for future detailed design of the plant have been predicted based on backward calculation of separation distance between the noise source and the nearest NSRs. The worst operation mode with 100% utilisation rate of equipment is assumed in the prediction. As such, the operation of the STP is expected to comply with all relevant noise criteria regardless of the operation mode.
The maximum allowable sound power levels (Max SWLs) of the identified fixed noise sources were determined by adopting standard acoustics principles:
SPL = Max SWL – DC + FC – BC
where
SPL:
Sound Pressure Level in dB(A)
Max SWL: Maximum Allowable Sound
Power Level in dB(A)
DC:
Distance Attenuation in dB(A) = 20 log D + 8 (where D is the distance in m)
FC:
Façade Correction in dB(A) = +3 dB(A)
BC:
Barrier Correction in dB(A)
For the existing STP at the entrance of Royal Palms, reference has been made to the noise level measured in the approved WSW Development EIA (EIA Report Register No. AEIAR- 120/2008). The plant operates 24 hours a day and the operational noise is assumed to be steady throughout the day based on the assumption in the approved WSW EIA Report and on-site verification on 3 and 17 May 2016. The sound power level from the approved WSW EIA Report (i.e. 73dB(A)) is adopted for the assessment.
For the MPVB, the maximum SWLs of the ventilation openings in accordance with the MPVB design provided by MTRC have been adopted for assessment. Correspondence from MTRC is shown in Appendix 4.1.
Corrections of tonality, intermittency or impulsiveness have not been considered in proposed fixed noise source as there are no detailed information and noise specification for these planned noise sources. However, if the noise exhibits any of these characteristics during the operation of the plant, the maximum allowable SWLs should be reduced in accordance with the recommendation given in Section 3.3 of the IND-TM.
In approved WSW VEP (VEP-538/2017), there is an E&M building at the same location of the proposed interim STP in this project as shown in Figure 6 of the approved EP-311/2008/E. The scope of the approved WSW VEP does not include the proposed interim STP as the WSW Development relies on the public sewerage network. In contrast, the scope of this project as indicated in Section 1.1, a 1-storey high building structure with basement is proposed to house an interim STP on-site as a temporary measure to handle the sewage generated from the development before the availability of public sewerage connection. The E&M building (as mentioned of the preferred option in Section 2.6) is found to be suitable to house the proposed interim STP and the associated effluent reuse facilities in the basement of the building. The Project Engineer has confirmed that the works in the construction of the 1-storey high building structure for the proposed interim STP will be the same as the E&M building as indicated in approved master layout plan of the approved WSW VEP.
The footprint of the STP building is about 225 m2. Only few number of PME will be operated simultaneously during the construction period. The extent of the STP building construction works for the Project will be minimum and shallow foundations will be adopted. No noisy operations are expected for the STP building construction works due to the small footprint of STP building.
Based on observation made during site visits on 3 and 17 May 2016, 9m and 10m high continuous noise barriers were erected around the perimeter of the WSW development site in accordance with requirement of the approved WSW Development EIA (AEIAR-120/2008). The construction site of STP is located within these barriers and will also benefit from the existing measure where noise sources of construction equipment will be blocked at all identified representative NSRs. The photos of the existing noise barriers are shown in Figure 4.4.
Given that the locations of the identified representative NSRs are of same conditions to that in the approved WSW EIA Report, the continuous vertical noise barriers which would be in place during the whole construction period of the proposed interim STP are considered to be sufficient to alleviate the potential construction noise impact from the proposed Project.
The construction programme for the Project is expected to overlap with the construction of the WSW Development from Q3 2018 to 2021. Quantitative construction noise impact assessment of the WSW Development for worst-case scenario with all construction activities including the construction of building structure for the proposed STP has already been conducted in the Environmental Review Report (ERR) for the WSW VEP and excerpted in Appendix 4.2. The plant inventory including the type and quantity of equipment and utilisation rate in the assessment was confirmed with the Project Engineer and remain valid subsequent to the design development for constructing the proposed interim STP.
The predicted cumulative construction noise levels at the representative NSRs with the implemented temporary noise barriers as shown in Figure 4.4 has been assessed and summarised in Table 4.6 below.
Table 4.6: Maximum Predicted Cumulative Construction Noise Levels at Representative NSRs
|
NSR ID |
Description |
Maximum Predicted Construction Noise Level, Leq(30mins), dB(A) |
Daytime Construction Noise Criteria*, Leq(30mins), dB(A) |
|
NSR 1 |
House No. 7, Cherry Path, Palm Springs |
70 |
75 |
|
NSR 2 |
House No. 1, Narcissus Path, Palm Springs |
71 |
75 |
|
NSR 3 |
House No. 61, Narcissus Path, Palm Springs |
70 |
75 |
|
NSR 4 |
St Lorraine English Kindergarten |
65 |
70 (65 for examination period) |
|
NSR 5 |
House No. 1, Ventura Avenue, Royal Palms |
74 |
75 |
|
NSR 6 |
House No. 1, Marin Avenue, Royal Palms |
70 |
75 |
|
NSR 7 |
House No. 202, Mai Po San Tsuen |
68 |
75 |
Source (*): EIAO-TM, Annex 5, Table 1B - Noise Standards for Daytime Construction Activities.
The noise assessment in the ERR for the WSW VEP (VEP-538/2017) has assessed the worst-case scenario with all construction activities at the WSW development site including the construction of building structure for the STP and demonstrated all the predicted noise levels at representative NSRs are complied with the relevant EIAO-TM construction noise criteria with implementation of the temporary continuous noise barriers. The construction works that were not covered in the noise assessment of ERR for the WSW VEP include installation works of the equalization tank, compartment and equipment of the STP only which will all be conducted inside the enclosed building structure. Therefore, the construction noise for the installation works is expected to be insignificant and the construction noise impact assessment in the ERR for the WSW VEP and no adverse cumulative noise impacts are anticipated.
As all construction activities are anticipated to be within the existing WSW Development construction site. To further reduce the construction noise impact, the sequence of works of the Project would be scheduled to prevent overlapping with other construction activities of the WSW Development by breaking the construction works into different phases / groups as far as practicable.
Considering the above, and with the implementation of measures detailed in Section 4.9.1 as well as the existing continuous noise barriers implemented for the construction phase of the WSW Development, adverse construction noise impact is not anticipated.
Based on the preliminary design information, the proposed interim STP will have one ventilation opening of on the western façade of the building structure as shown in Figure 4.2. Adopting the methodology stated in Section 4.7.2, the maximum allowable SWLs of the only ventilation opening identified at the western façade during different time periods have been predicted and are summarised in Table 4.7 below. Detailed calculation is shown in Appendix 4.3.
Table 4.7: Maximum Allowable SWL and Predicted Fixed Plant Noise Levels
|
NSR ID |
Day-time and evening (0700-2300 hours) |
Night-time (2300-0700 hours) |
||||
|
Maximum Allowable SWL |
Predicted Noise Level, |
Noise Criterion Leq(30mins), dB(A) |
Maximum Allowable SWL |
Predicted Noise Level, |
Noise |
|
|
NSR 8 |
92 |
47 |
51 |
86 |
41 |
45 |
|
NSR 9 |
92 |
43 |
51 |
86 |
37 |
45 |
|
NSR 10 |
92 |
51 |
51 |
86 |
45 |
45 |
With the consideration of both day-time and evening criterion (i.e. 51 dB(A)) and night-time criterion (i.e. 45 dB(A)), the maximum allowable SWLs for the proposed interim STP calculated is 92 dB(A) for day-time and evening and 86 dB(A) for night-time. Appropriate noise reduction design at source will be considered (such as acoustic louver blade or ventilation silencers, etc.) during the detailed design stage to ensure the required maximum allowable SWLs is achieved. As stated in Section 4.11.2 and the Environmental and Monitoring Manual, noise commissioning test prior to the operation of the Project is required to ensure the noise associated with the fixed plant operation would comply with the noise standards stipulated in the EIAO-TM and the NCO.
With the adoption of the maximum allowable SWLs for the proposed interim STP, the predicted noise level at all identified representative NSRs is expected to comply with the relevant noise criteria. Therefore, no adverse fixed noise sources impacts on nearby NSRs are anticipated.
As discussed in Section 4.8.1, all construction activities are anticipated to be within the existing WSW Development construction site. With the continuous noise barriers implemented under the approved WSW Development EIA Report (AEIAR-120/2008) and VEP (VEP-538/2017) as shown in Figure 4.4, no adverse construction noise impact is anticipated.
Nevertheless, the following noise control measures are recommended to reduce potential noise impact from construction activities:
● Good Site Practice;
● Selection of quieter plant;
● Use of enclosure / acoustic shed;
● Use of Insulating Fabric; and
● Schedule of the use of PME
Good site practice and noise management can significantly reduce the impact of site activities on nearby NSRs. The measures should be followed as far as practicable during construction:
● Only well-maintained plant should be operated on-site and plant should be serviced regularly;
● Machines and plants that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum;
● Mobile plant, if any, should be sited as far from NSRs as possible;
● Plant known to emit noise strongly in one direction should, wherever possible, be orientated to direct noise away from NSRs;
● Material stockpiles and other structures should be effectively utilized, wherever practicable, in screening noise from on-site construction activities;
● Silencers or mufflers on construction equipment should be utilized and should be properly maintained during construction works; and
● Routine maintenance of plant and equipment should be carried out.
Quiet plant is defined as Quality Powered Mechanical Equipment (QPME) whose actual SWL is less than the value specified in GW-TM for the same piece of equipment. This is one of the most effective measures and is increasingly practicable because of the availability of quiet equipment.
The Contractor may be able to obtain particular models of plant that are quieter than the standards given in the GW-TM. The SWLs for specific quiet plant can be taken from EPD’s QPME Inventory.
The use of noise enclosure or acoustic shed is to cover stationary PME such as air compressor and generator. With the adoption of the noise enclosure or acoustic shed, the PME could be completely screened and the noise emission at source can be effectively reduced.
Noise insulating fabric should be adopted for certain PME where applicable. With the adoption of the fabric, noise emission from the opening or gaps of the joints of the PME can be effectively reduced.
The construction activities should be scheduled, where practicable, to prevent the use of multiple PMEs simultaneously.
With the proposed interim STP designed to meet the maximum allowable sound power levels as stated in Section 4.8.2, no exceedance of relevant noise criteria is anticipated, and hence no mitigation measure is required. Noise commissioning test should be carried out prior to the operation of the proposed STP to ensure the compliance of the noise levels from the operation of the STP with the stipulated noise criteria.
With the continuous vertical noise barriers along the perimeter of the WSW development site and the noise barriers would be in place when works for the proposed interim STP is carried out, the predicted construction noise levels at the representative NSRs will comply with the relevant noise criteria. No residual noise impact during construction phase is expected.
With the adoption of maximum allowable sound power levels as described in Section 4.8.2, all predicted noise levels at identified NSRs will comply with the relevant noise criteria. No residual noise impact during operation phase is anticipated.
The extent of the STP construction works represent only a small part of the proposed WSW Development. As regular noise monitoring of the on-going EM&A programme for the proposed WSW Development would be carried out during the whole construction period of the Project, no noise monitoring is proposed under this project during the construction phase of the proposed STP.
Construction works are expected to be of small scale and localized. Potential cumulative construction noise impacts from the construction of the proposed Project and the WSW Development have been identified and assessed. Under the consideration of the prevailing site condition with vertical noise barriers during the whole construction period of the proposed interim STP, no adverse construction noise impact is anticipated.
Potential cumulative fixed noise impacts from the operation of the proposed Project and the existing noise sources have been identified and assessed. The maximum allowable sound power levels for the operation of the proposed interim STP have been determined as 92 dB(A) for day-time and evening periods and 86 dB(A) for night-time period.
With the adoption of the maximum allowable sound power levels for the proposed STP, no exceedances in relevant noise criteria is expected. No adverse fixed noise impact during operation phase is anticipated.
A noise commissioning test should be conducted prior to the operation of the proposed STP and implemented as specified in the standalone Environmental Monitoring and Audit Manual.
The interim STP will be decommissioned when the WSW Development is connected to the committed public sewer. The STP will only cease operation and the structure of the STP and its associated infrastructure will not be demolished. Therefore, no noise impact is anticipated during decommissioning phase.