4.1.1
This
section provides an evaluation of the potential noise impacts arising from the
construction and operation of the proposed Project. The Study Area is generally
defined by a distance of 300 m away from the boundary of the Project Site.
Appropriate mitigation measures will be recommended, where necessary, to
mitigate any unacceptable impacts.
4.2.1
The
principal legislation relating to the control of construction noise is the
Environmental Impact Assessment Ordinance (Cap. 499). The Technical Memorandum on Environmental
Impact Assessment Process (EIAO-TM), issued under the EIAO, provides guidelines
and noise criteria for evaluating noise impacts. The assessment criteria are defined in Annex 5 of the EIAO-TM.
4.2.2
The
Noise Control Ordinance (NCO) (Cap. 400) also provides means to assess
construction noise impacts. A number of
Technical Memoranda (TMs) have been issued under the NCO to stipulate control approaches and criteria. The Technical Memorandum on Noise from
Construction Work Other than Percussive Piling (GW-TM), which provides the
guidelines for controlling the construction noise from powered mechanical
equipment (PME) in general construction works, is applicable to the control of
noise impacts from the construction of this Project.
4.2.3
Under
the EIAO, potential noise impact arising
from general construction works during normal working hours (i.e. 0700 to 1900
hrs on any day not being a Sunday or public holiday) at 1 m 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 construction noise standards are
presented in Table 4.1.
Table 4.1 - EIAO-TM Day-time
Construction Noise Standards
Use |
Noise Standard |
Domestic premises |
75 |
Educational institutions |
70 |
Educational institutions (during examination periods) |
65 |
Notes:
1.
The above standards apply to
building uses which rely on opened windows for ventilation.
2.
The above standards shall be
viewed as the maximum permissible noise levels assessed at 1m from the external
façade.
4.2.4
The NCO
provides statutory controls on general construction works during restricted
hours (i.e. 1900 - 0700 hrs Monday to Saturday and at any time on Sundays and
public holidays). The use of PME for
carrying out construction works during these restricted hours would require a
Construction Noise Permit (CNP). The
Noise Control Authority will assess
all CNP applications on a case-by-case basis guided by the GW-TM.
4.2.5
When
assessing an application for CNP for the use of PME during restricted hours,
the Noise Control Authority will compare the Acceptable Noise Levels (ANLs)
specified in the GW-TM with the Corrected Noise Levels (CNLs) (i.e. after
accounting for factors such as barrier effects and reflections) associated with
the proposed PME operations. The NCO
requires that noise levels from construction at affected Noise Sensitive
Receiver (NSR) be less than the specified ANL.
The ANLs are related to the inherent noise sensitivity of the noise
receiver areas in question, and different area sensitivity ratings (i.e. A, B
or C, see Table 4.2) have been
established to reflect the background characteristics of different areas. Each noise receiver area is assigned an area
sensitivity rating based on its predominant land use and the presence, if any,
of Influencing Factors (IFs) such as nearby industrial areas, major roads or
airports. The appropriate area
sensitivity rating for the NSR is determined with reference to Table
4.2.
Table 4.2 –
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.
4.2.6
The
relevant ANLs for each area sensitivity rating are shown in Table 4.3.
Table 4.3 -
Acceptable Noise Levels (ANLs) for General Construction Works to be carried out
during Restricted Hours (GW-TM)
Time
Period |
Area
Sensitivity Rating |
||
A |
B |
C |
|
All days
during the evening (i.e. 1900-2300 hrs) and general holidays (including
Sundays) during the day and evening (i.e. 0700-2300 hrs) |
60 |
65 |
70 |
All days
during the night-time (i.e. 2300-0700 hrs) |
45 |
50 |
55 |
Notes:
The
above standard applies to uses which rely on opened windows for ventilation.
4.2.7
The
Noise Control Authority will consider a well-justified CNP application for
construction works within restricted hours as guided by the relevant Technical
Memorandum 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. Factors influencing the outcome of a CNP
application, such as the assigning of ANLs, would be determined by the Noise
Control Authority at the time of the application review based on the prevailing
site conditions which may change from time to time.
4.2.8
The
Technical Memorandum on Noise from Construction Works in Designated Areas
(DA-TM) issued under the NCO indicates a list of Specified Powered Mechanical Equipment
(SPME) and the types of Prescribed Construction Work (PCW) to be regulated
within restricted hours in Designated Areas (DAs). Under the DA-TM, the use of five types of
SPME and the carrying out of three types of PCW within a designated area during
restricted hours would require a valid CNP.
The SPME includes hand-held breaker, bulldozer, concrete lorry mixer,
dump truck and hand-held vibratory poker.
The PCW are:
·
Erecting or dismantling of formwork or scaffolding;
·
Loading, unloading or handling of rubble, wooden
boards, steel bars, wood or scaffolding material; and
·
Hammering.
4.2.9
The
Project site falls within the designated area under the NCO (ref. EPD/AN/NT-02). The Noise Control Authority will assess
the CNP applications based on procedures and requirements as described in the
DA-TM. In general, it should not be
presumed that a CNP would be granted for the carrying out of PCW within a
designated area during the restricted hours.
The CNP may be granted for the execution of construction works within a
designated area during restricted hours involving the use of SPME if the
relevant ANL and criteria stipulated in the DA-TM can be satisfied.
4.2.10
Fixed
plant noise associated with the operation of a project is controlled under
Section 13 of the NCO. The Technical
Memorandum on Noise from Places Other than Domestic Premises, Public Places or
Construction Sites (IND-TM)
specifies the applicable ANLs for assessing potential operational noise
impacts. The noise standards 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 4.4) as specified in the IND-TM; or
·
Where
the prevailing background noise level in the area is 5 dB(A) or more below the
appropriate ANL, the total fixed source noise level must not exceed this noise
level.
4.2.11
The
noise criteria stipulated in the IND-TM apply for all days and general
holidays. The ANLs are dependent on the
area sensitivity rating of the NSRs and the time of the day and are presented
in Table 4.4.
Table 4.4 –
Acceptable Noise Levels for used as Operational Noise Criteria
Time Period |
Leq 30min
(dB(A)) |
||
Area sensitivity rating “A” |
Area sensitivity rating “B” |
Area sensitivity rating “C” |
|
Day-time (0700 - 1900
hrs) |
60
(55) |
65
(60) |
70
(65) |
Evening (1900 - 2300
hrs) |
60
(55) |
65
(60) |
70
(65) |
Night-time (2300 -
0700 hrs) |
50
(45) |
55
(50) |
60
(55) |
Note:
The number in brackets
indicates the noise limit (ANL -5 dB(A)) for operational noise impact
assessment.
4.2.12
The main
Sha Tau Kok area is located within Closed Area and is only partly covered by
the Sha Tau Kok Outline Zoning Plan (No. S/NE-STK/2). Given its rural
environment, the identified NSR has been assigned an area sensitivity rating of
“A”.
4.2.13
Baseline
noise measurements were conducted in January 2014 to determine the prevailing
background noise levels near the Project area. Results are summarized in in Section 4.3 and Annex
4A. Noise criteria has been assigned to the NSRs that will be affected
by the operational noise from the expanded STKSTW based on the ANL (Table 4.4) and the prevailing noise
levels (Table 4.5), as tabulated in Table 4.6.
4.2.14
In any event, the noise criteria employed in this
Report is for an indicative
operational noise 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. Nothing in this Report shall bind
the Noise Control Authority in the context of law enforcement against any fixed
noise source being assessed.
4.3.1
Sha Tau
Kok is situated within a quiet rural area. The existing ambient noise levels
are mainly generated by cross boundary traffic along Sha Tau Kok Road, Sha Ho
Road and nearby local roads. Other noise sources include community activities,
marine traffic and tour activities at Chun Ying Street.
4.3.2
Baseline
noise measurements to investigate the prevailing background noise levels near
the Project area have been undertaken in January 2014. Measurement results and locations are
presented in Annex
4A and summarised in Table 4.5.
Table 4.5 – Measured Baseline
Noise Levels
Measurement Station |
Measurement Location |
Time Periods |
Measured Noise Levels, Leq, 30min
dB(A) |
N1 |
Junction of Sha
Tau Kok Road – Shek Chung Au and Shan Tsui Village Road |
Day-time/evening: 0700 to
2300 hrs |
61 – 77 |
Night-time:2300 to 0700 hrs |
56 – 77 |
||
N2 |
Sha Tau Kok
Police Operation Base |
Day-time/evening: 0700 to
2300 hrs |
49 – 60 |
Night-time:2300 to 0700 hrs |
50 |
||
N3 |
Sha Tau Kok Chuen
Block 1 |
Day-time/evening: 0700 to
2300 hrs |
62 – 75 |
Night-time:2300 to 0700 hrs |
56 – 73 |
||
N4 |
Sha Tau Kok Chuen
Block 44 |
Day-time/evening: 0700 to
2300 hrs |
60 – 72 |
Night-time:2300 to 0700 hrs |
42 – 71 |
||
N5 |
Sha Tau Kok Chuen
Block 13 |
Day-time/evening: 0700 to
2300 hrs |
58 – 71 |
Night-time:2300 to 0700 hrs |
58 – 74 |
||
N6 |
Sha Tau Kok
Central Primary School |
Day-time/evening: 0700 to
2300 hrs |
45 – 68 |
Night-time:2300 to 0700 hrs |
35 – 70 |
||
N7 |
Proposed Sha Tau
Kok Chuen development site |
Day-time/evening: 0700 to
2300 hrs |
57 – 75 |
Night-time:2300 to 0700 hrs |
56 – 67 |
||
N8 |
Shun Lung Street |
Day-time/evening: 0700 to
2300 hrs |
53 – 67 |
Night-time:2300 to 0700 hrs |
41 – 66 |
4.3.3
Based on
the measured baseline noise levels, the noise criteria for operational noise
assessment at NSRs that will be affected by the operational noise from the
expanded STKSTW has been determined and tabulated in Table 4.6 below.
Table 4.6 – Noise Criteria for
Operational Noise Impact Assessment
Measurement Station |
Representative NSRs |
Time Periods |
Measured Noise Levels, Leq, 30min
dB(A) |
ANL-5, dB(A) |
Operational Noise Criteria, dB(A)* |
N1 |
NSR 1, NSR 2 |
Day-time/evening: 0700 to
2300 hrs |
61 – 77 |
55 |
55 |
Night-time:2300 to 0700 hrs |
56 – 77 |
45 |
45 |
||
N6 |
NSR 3 |
Day-time/evening: 0700 to
2300 hrs |
45 – 68 |
55 |
45 |
Night-time:2300 to 0700 hrs |
35 – 70 |
45 |
35 |
||
N3 |
NSR 4, NSR 5 |
Day-time/evening: 0700 to
2300 hrs |
62 – 75 |
55 |
55 |
Night-time:2300 to 0700 hrs |
56 – 73 |
45 |
45 |
||
N4 |
NSR 6 |
Day-time/evening: 0700 to
2300 hrs |
60 – 72 |
55 |
55 |
Night-time:2300 to 0700 hrs |
42 – 71 |
45 |
42 |
||
N7 |
NSR 7 |
Day-time/evening: 0700 to
2300 hrs |
57 – 75 |
55 |
55 |
Night-time:2300 to 0700 hrs |
56 – 67 |
45 |
45 |
||
N8 |
NSR 8 |
Day-time/evening: 0700 to
2300 hrs |
53 – 67 |
55 |
53 |
Night-time:2300 to 0700 hrs |
41 – 66 |
45 |
41 |
||
N2 |
NSR 9 |
Day-time/evening: 0700 to
2300 hrs |
49 – 60 |
55 |
49** |
Night-time:2300 to 0700 hrs |
50 |
45 |
** |
Note:
*
ANL -5 dB(A) or the prevailing background noise levels (for quiet areas with
level 5 dB(A) below the ANL).
**
For NSR 9 (Tin Hau Temple), night-time (2300 to 0700 hrs) use is not expected.
The noise criteria for day-time / evening (0700 to 2300 hrs) is adopted.
4.4.1
In
accordance with the requirements stated in
Clause 3.4.3.2 of the EIA Study Brief, the Study Area for the noise impact
assessment shall covered an area of 300 m from the boundary of the Project
Site. The assessment area will be
reduced accordingly if the first layer of NSRs, closer than 300 m from the
outer Project limit, provides acoustic shielding to those receivers at
distances further away from the Project. The representative NSRs closest to the
Project Site was identified. If these worst affected representative NSRs comply
with the relevant noise standards, the NSRs further away will also comply with
the relevant noise standards according to acoustic principles. Representative
NSRs identified according to the criteria set out in the EIAO-TM are shown in Figure 4.1 and are indicated in Table
4.7. Photos of the NSRs are shown in
Annex 4B. Reference has
been made to the approved Sha Tau Kok Outline Zoning Plan (No. S/NE-STK/2) in
identifying appropriate NSRs. In addition, site visits have been conducted to
verify the NSRs and its assessment point.
4.4.2
Apart
from the future residences of NSR 7, there are no planned NSRs in the Study
Area.
4.4.3
According
to information from the HKPF, the Police Operation Base adjacent to STKSTW is
used mainly as staff changing rooms, canteen, kitchen, laundry and fitness
centre, while the Operation Base – Sha Tau Kok Division Border District is used
for working only. There is no staff quarter in the nearby Sha Tau Kok Fire
Station. As such, they are not considered as NSR.
Table 4.7 – Representative
Noise Sensitive Receivers (NSRs)
NSR ID |
Description |
Type of Usage |
No. of Floors |
Approximate Distance from Notional Source
Positon of Work to NSR, m |
Approximate Distance from the boundary of the
Operational Noise Source to NSR, m |
||||
STKSTW |
HDD |
Gravity Sewers |
STKSPS |
STKSTW |
TSTP |
||||
NSR
1 |
Village house at Ha Tam Shui
Hang |
Residential |
3 |
143 |
141 |
165 |
498 |
124 |
175 |
NSR
2 |
Village house at Ha Tam Shui
Hang |
Residential |
3 |
150 |
164 |
85 |
414 |
140 |
185 |
NSR
3 |
Sha Tau Kok Central Primary
School |
Educational |
6 |
405 |
456 |
163 |
152 |
392 |
409 |
NSR
4 |
Block 1, Sha Tau Kok Chuen |
Residential |
4 |
170 |
214 |
73 |
268 |
154 |
186 |
NSR
5 |
Sun Ying Lau, No. 10 Sha Tau
Kok Road |
Residential |
5 |
199 |
252 |
87 |
198 |
184 |
200 |
NSR
6 |
Block 45, Sha Tau Kok Chuen |
Residential |
5 |
195 |
252 |
16 |
180 |
172 |
175 |
NSR
7* |
Future Sha Tau Kok Chuen (under construction) |
Residential |
5 |
320 |
375 |
18 |
61 |
304 |
304 |
NSR
8 |
Building along Shun Lung Street |
Residential |
4 |
395 |
452 |
16 |
23 |
382 |
384 |
NSR
9 |
Tin Hau Temple |
Place
of Public Worship |
1 |
90 |
140 |
70 |
290 |
74 |
70 |
4.5.1
The
Project includes the following main construction works:
·
expansion
of the Sha Tau Kok Sewage Treatment Works (STKSTW);
·
construction
of a temporary sewage treatment plant (TSTP);
·
demolition
of the existing Sha Tau Kok Sewage Pumping Station (STKSPS) and decommissioning
of the rising main between STKSPS and STKSTW;
·
construction
of new gravity sewers; and
·
decommissioning of the existing submarine outfall and
construction of a new one.
4.5.2
The
details of Project are given in Section 2. The major
construction activities during the construction phase will include site
clearance, demolition of existing structures, excavation, construction of
substructure/superstructure, backfilling works and E&M installation.
Potential sources of noise impacts during the construction phase of the Project
will mainly arise from Powered Mechanical
Equipment (PME) operating at the construction sites. Based on the
current engineering design, percussive piling and blasting are not required.
Ground-borne construction noise is not envisaged from the above construction
activities.
4.5.3
The
submarine outfall will be constructed by Horizontal Directional Drilling (HDD)
method. A launching pit will be constructed within the STKSTW for drilling
works. A cofferdam will be constructed at the proposed outfall area to form a
receiving pit to retrieve the drill head, excavation of marine sediment and
construction of the outfall diffuser. The receiving pit works site will be on
marine waters well over 1 km from Sha Tau Kok town. The associated noise impact
at the receiving pit is expected to be negligible and is not assess further. In
addition, HDD will start construction from the STKSTW towards the sea (Starling
Inlet) and will not drill underneath any NSRs. Ground-borne construction noise
is therefore not envisaged. The indicative location of the launching and
receiving pits is shown in Figure 4.1.
4.5.4
The
laying of gravity sewers involved mainly open trench method (cut and cover) and
trenchless method. Trenchless method is adopted at the section outside Sha Tau
Kok Playground to minimize impact to the nearby Tin Hau Temple. The location of
the trenchless works is shown in Figures 2.1a&b. For the
trenchless method, majority of the PME will be underground. Noise generated for
trenchless method is therefore assumed to be largely similar to the noise level
during open trench. For the open trench method, construction works will
generally take place in sections to minimize inconvenience to public from road
closure. The construction works will take place in sequences, such as
excavation, welding of trench support, pipe laying, backfilling, compaction and
resurfacing. Each work front will be around 20m to 30m in length and will last
for about one to two months.
4.5.5
For the
decommissioning of the existing outfall and rising main, grout or foam concrete
will be used to fill the pipe to avoid the need for excavation. Works will be
conducted at both ends of the rising main (i.e. within the STKSTW and STKSPS)
and within the STKSTW for the outfall, only upon operation of the expanded
STKSTW and new outfall.
4.5.6
Upon
completion of all construction works, the existing STKSPS will be demolished.
4.5.7
Based on
the current programme, no construction works will be required during the
restricted hours under the NCO. The
normal working hours of the construction of the Project will be between 0700
and 1900 hours from Monday to Saturday (except general holidays). Should evening and night works between 1900
and 0700 hours or on public holidays (including Sundays) be required, the
Contractor will submit a CNP application which will be assessed by the Noise
Control Authority.
4.5.8
During
operation, noise will be generated from fixed plant sources at the expanded
STKSTW. These include screens, blowers,
pumps and fans. Most of the equipment will be located inside the plant rooms
and hence fully enclosed.
4.5.9
The main
areas of the expanded STKSTW that will generate operational noise (see Annex D for
location) are:
·
preliminary
treatment area;
·
sludge
dewatering and thickening area;
·
air
blower area;
·
MBR
area; and
·
outfall
pumping area.
4.5.10
A TSTP (see Figure
4.1 and Annex E
for location) is proposed as the interim measure to cope with the sewage flow
in order to isolate the existing STKSTW to facilitate its expansion. The TSTP
will employ secondary treatment process at a
treatment capacity of 2,500 m3/day.
4.6.1
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 sound power levels (SWLs) to the PME
proposed based on the GW-TM and
list of SWLs of other commonly used PME[1];
·
Calculate the correction factors based on the
distance between the NSRs and the notional noise source positions of different
works 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.
4.6.2
The
construction noise assessment was undertaken based on the proposed construction
works programme and plant inventory, and appropriate
utilisation rates of the PME items (Annex 4C). The design engineer has reviewed the
programme and plant inventory, and has confirmed that they are reasonable and
practicable for completing the Project within the scheduled timeframe.
4.6.3
For the
purpose of assessing the worst case scenario in the construction noise
assessment, the proposed Project was divided into five separate works
activities, namely (A) expansion of STKSTW / construction of TSTP, (B)
construction of submarine outfall using HDD, (C) laying of gravity sewers, (D)
decommissioning of the existing outfall and rising main, and (E) demolition of
STKSPS.
4.6.4
For
worst case assessment, the works (A) expansion of STKSTW / construction of
TSTP, (B) construction of submarine outfall using HDD and (C) laying of gravity
sewers is assumed to overlap. Expansion
of STKSTW will commence upon completion of the TSTP hence the works will not
overlap. Decommissioning of the existing outfall and rising main (D) will be
conducted only upon operation of the STKSTW. Finally, demolition of STKSPS (E)
will be conducted upon completion of all main construction and operation of the
STKSTW, hence both works (D) and (E) will not overlap and are assessed
separately.
4.6.5
The
total SWL associated with each construction activity for the corresponding
works areas was established. The
potential noise impacts at NSRs were subsequently evaluated by comparing the
predicted noise levels with the EIAO-TM day-time construction noise limits.
4.6.6
The
methodology for the operational 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;
·
Assign sound power levels (SWLs) to the proposed
equipment, with
reference to other approved EIA studies
in similar nature,
Good Practices on Pumping System Noise Control (GP-PS) and Good Practices on
Ventilation System Noise Control (GP-VS);
·
Identify representative NSRs that may be
affected by the fixed plant;
·
Calculate the correction factors, using a
conservative approach, based on the horizontal distance between the NSRs and
the fixed plant sources;
·
Calculate the corrected noise levels after
taking into account other corrections such as potential screening effects by
adopting standard acoustics principles; and
·
Present the results in terms of Leq, 30min
dB(A), as specified in the IND-TM.
4.6.7
The
equipment inventory and operation modes have been provided by design engineer
and validated by DSD.
4.6.8
The main
operating areas of the expanded STKSTW that will generate operational noise
are:
·
Area
A: preliminary treatment area;
·
Area
B: sludge dewatering and thickening area;
·
Area
C: air blower area;
·
Area
D: MBR area; and
·
Area
E: outfall pumping area.
4.6.9
For the
expanded STKSTW, distance attenuation was taken into account in the noise
calculations where the direct distance between the nearest boundary of each
operating area and each of the representative NSRs in the vicinity was
estimated. All the equipment will be
totally enclosed inside building structure.
The exhaust fans will be fitted with acoustic louvre/silencer. Barrier correction was considered in which a
noise reduction of 20 dB(A) was applied for equipment that are fully enclosed
within the concrete building structure and 10 dB(A) reduction was applied to
the exhaust fan with acoustic louver/silencer.
A positive 3 dB(A) correction was included in the calculations to
predict the noise levels at the NSRs due to façade effect.
4.6.10
For the
TSTP, the noise source is assumed to be located at the boundary of the TSTP
closest to the respective NSR. The pumps and air blowers will be enclosed
within a tank and acoustic enclosure respectively, in which a noise reduction
of 20 dB(A) was applied. The screens may be located outdoor but will be
protected by weatherproof steel casing. The deodourizing unit may also be
located outdoor but the fan will be enclosed inside the deodourization unit
with the exhaust facing away from the NSRs (i.e. towards the sea). A noise
reduction of 10 dB(A) has been applied to the screens and deodourization unit.
A positive 3 dB(A) correction was included in the calculations to predict the
noise levels at the NSRs due to façade effect.
4.6.11
The TSTP
will cease to operate once the expanded STKSTW is in operation and will only
act as a standby during the testing and commissioning stage. It will ultimately
be removed from site. Concurrent operation of both the expanded STKSTW and TSTP
is not expected.
4.7.1
The
predicted construction noise levels during the construction phase are
calculated in accordance with the methodology described in GW-TM. The results
are summarised in Table 4.8 with details of the noise calculations given
in Annex 4C.
Table 4.8 –
Predicted Construction Noise Levels (Without Mitigation Measures)
NSR ID |
Description |
Predicted Noise Level, dB(A) |
NSR
1 |
Village house at Ha Tam Shui Hang |
62 –
77 |
NSR
2 |
Village house at Ha Tam Shui Hang |
64 – 77 |
NSR
3 |
Sha Tau Kok Central Primary School |
64 –
72 |
NSR
4 |
Block 1, Sha Tau Kok Chuen |
66 –
77 |
NSR
5 |
Sun Ying Lau, No. 10 Sha Tau Kok Road |
66 –
76 |
NSR
6 |
Block 45, Sha Tau Kok Chuen |
66 –
88 |
NSR
7 |
Future Sha Tau Kok Chuen (under construction) |
72 –
87 |
NSR
8 |
Building along Shun Lung Street |
80 –
89 |
NSR
9 |
Tin Hau Temple |
67 –
80 |
Noise
criteria for residential premises: 75 dB(A), educational institutions: 70 dB(A)
(65 dB(A) during examination). Noise criteria for NSR 9 (Tin Hau Temple)
assumed similar to residential premises.
4.7.2
Results
indicate that the construction noise levels at the majority of the
representative NSRs exceeded the EIAO-TM noise criteria in day-time during the
course of the construction period.
Therefore, mitigation measures will be required.
4.7.3
The
predicted fixed plant noise levels at the representative NSRs due to the
operation of the expanded STKSTW and TSTP are summarised in Table 4.9. The predicted noise levels at all the
representative NSRs comply with the day-time / evening and night-time noise
criteria. Details of the calculation are
given in Annex 4D and Annex 4E.
Table 4.9 – Predicted Fixed Plant Noise Levels due to the Expanded STKSTW and TSTP
NSR ID |
Description |
Predicted Fixed Plant Noise Level,
dB(A) |
Operational Noise Criteria, dB(A) |
Comply with Operational Noise Criteria |
||
STKSTW |
TSTP |
Daytime /
Evening |
Night-time |
|||
NSR
1 |
Village house at Ha Tam Shui
Hang |
38 |
35 |
55 |
45 |
Y |
NSR
2 |
Village house at Ha Tam Shui
Hang |
38 |
35 |
55 |
45 |
Y |
NSR
3 |
Sha Tau Kok Central Primary
School |
29 |
28 |
45 |
35 |
Y |
NSR
4 |
Block 1, Sha Tau Kok Chuen |
36 |
35 |
55 |
45 |
Y |
NSR
5 |
Sun Ying Lau, No. 10 Sha Tau
Kok Road |
35 |
34 |
55 |
45 |
Y |
NSR
6 |
Block 45, Sha Tau Kok Chuen |
35 |
35 |
55 |
42 |
Y |
NSR
7 |
Future Sha Tau Kok Chuen (under construction) |
31 |
30 |
55 |
45 |
Y |
NSR
8 |
Building along Shun Lung Street |
29 |
28 |
53 |
41 |
Y |
NSR
9 |
Tin Hau Temple |
41 |
43 |
49 |
* |
Y |
**
For NSR 9 (Tin Hau Temple), night-time (2300 to 0700 hrs) use is not expected.
The noise criteria for day-time / evening (0700 to 2300 hrs) is adopted.
4.8.1
In view
of the predicted noise exceedances during the construction of the Project, the
following mitigation measures have been considered:
·
Use
of quiet PME / quiet construction method;
·
Adoption
of temporary noise barriers;
·
Good
construction site practice; and
·
Scheduling
of PME / construction activities.
4.8.2
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. The total SWL of all
plant items to be used on-site at each works area will be specified so that
flexibility is allowed for the Contractor to select plant items to suit the
construction needs. Quiet PME that have
been adopted in the assessment are presented in Annex 4C.
4.8.3
During
demolition of existing structures in STKSTW and STKSPS, concrete crusher should
be used in place of the excavator mounted breaker. Alternatively, hand held
breaker or excavator mounted breaker of noise level similar to concrete crusher
can be considered.
4.8.4
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. The
use of noise barrier for certain PME could generally provide a 5 dB(A)
reduction for movable PME and 10 dB(A) for stationary PME. Movable noise barriers of 3 m 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.
4.8.5
Temporary
noise barriers in the form of purposely-built site hoarding should be erected
at the works boundary of the STKSTW. In addition, movable noise barriers should
be used for construction of gravity sewers.
4.8.6
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/m2 and have no openings or
gaps. The movable noise barrier will be
about 3 m tall and with a short cantilevered section on the top, if necessary,
such that the line of sight to the NSR is blocked by the barriers.
4.8.7
Good
construction site practice 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.
4.8.8
The
construction activities should be planned and carried out in sequence rather
than simultaneously at each location.
Therefore, only one unit of each type of equipment should be operated at
any one time. For open trench construction of the gravity sewers, each work
front should be around 20m to 30m in length.
4.8.9
With the
implementation of quiet PME / quiet construction method and temporary noise
barriers for various construction activities, the mitigated noise levels at the
representative NSRs were calculated and the results are summarised in Table 4.10 with details of the calculations given in Annex 4C. The results indicated that the predicted
construction noise levels comply with the EIAO-TM daytime construction noise
standards.
Table 4.10 –
Predicted Construction Noise Levels (With Mitigation Measures)
NSR ID |
Description |
Predicted Noise Level, dB(A) |
NSR
1 |
Village house at Ha Tam Shui Hang |
47 –
63 |
NSR
2 |
Village house at Ha Tam Shui Hang |
49 – 64 |
NSR
3 |
Sha Tau Kok Central Primary School |
57 –
59 |
NSR
4 |
Block 1, Sha Tau Kok Chuen |
52 –
64 |
NSR
5 |
Sun Ying Lau, No. 10 Sha Tau Kok Road |
55 –
62 |
NSR
6 |
Block 45, Sha Tau Kok Chuen |
56 –
75 |
NSR
7 |
Future Sha Tau Kok Chuen (under construction) |
65 –
74 |
NSR
8 |
Building along Shun Lung Street |
74 –
75 |
NSR
9 |
Tin Hau Temple |
52 –
68 |
Noise
criteria for residential premises: 75 dB(A), educational institutions: 70 dB(A)
(65 dB(A) during examination). Noise criteria for NSR 9 (Tin Hau Temple)
assumed similar to residential premises.
4.8.10
While no
noise impact is expected due to the operation of fixed plant items, it is still
recommended that the following measures be implemented to minimise the
potential impact:
·
All the equipment will be totally enclosed
inside building structure;
·
Quieter equipment should be chosen;
·
Include noise levels specification when ordering
new equipment items;
·
All openings, including louvres for ventilation
and machine room doors should be oriented away from the NSRs;
·
Silencers, acoustic louvres or acoustic doors
should be used where necessary; and
·
Develop and implement a regularly scheduled
equipment maintenance programme so that equipment items are properly operated
and serviced. The programme should be implemented by properly trained
personnel.
4.8.11
No secondary
impact is expected from the mitigation measures proposed in the EIA report.
4.9.1
With the
implementation of practical noise mitigation measures, including the use of
quiet PME / quiet construction method, temporary noise barriers, and good site
practices, it is predicted that there is no exceedance of the daytime
construction noise criteria at all NSRs.
Therefore, no residual impact is anticipated.
4.9.2
By enclosing
the fixed-noise sources and use of acoustic louvres, the predicted operational
noise is within the relevant noise criteria. Therefore, no residual
impact is anticipated.
4.9.3
No
residual impact is identified in the EIA report. Hence, no additional study is
required.
4.10.1
According to Table 2.11, two projects will likely be
conducted concurrently with the proposed Project.
·
Sediment
Removal at Sha Tau Kok Fish Culture Zone, Boat Shelter and Approach Channel
(CEDD)
·
CE
78/2014 (DS) Drainage Improvement Works at North District – Package B (DSD)
4.10.2
The CEDD
sediment removal project will mainly be marine dredging works conducted in
Starling Inlet. The project is a designated project and an EIA study is being
conducted. Details of the construction works and programme are not yet available at the time of assessment. Nonetheless, it
is envisaged that such dredging works would require limited construction
equipment (mainly grab dredger). Adverse cumulative impact is not expected.
Close liaison with responsible department will be carried out to formulate a
best programming to minimise project interfaces.
4.10.3
For the
DSD drainage improvement works, some of the drainage works will have interface
with the proposed gravity sewers. Details of the construction works and programme are not yet available at the time of
assessment. Close liaison with responsible department will be carried out to
formulate a best programming to minimise project interfaces. Appropriate
phasing of the proposed gravity sewers works will be carefully considered to
avoid multiple or repeated road openings to minimize nuisance to the public.
Possibility of entrustment of works will be considered. By avoiding concurrent
works, adverse cumulative impact is not expected.
4.10.4
No cumulative operational noise impact is expected.
4.11.1
The recommended mitigation measures, monitoring procedures
and locations are summarised in detail in the Environmental Monitoring and
Audit (EM&A) Manual. This will
facilitate the Contractor to have early warning and undertake the necessary
actions to reduce noise emissions at specific areas. The effectiveness of on-site control measures
could also be evaluated through the regular site audits. All the recommended mitigation measures
should be incorporated into the EM&A programme for implementation during
construction.
4.11.2
Since
the predicted operational noise levels at all NSRs are well within the relevant
noise criteria, commissioning test and noise monitoring for the expanded STKSTW
and TSTP is considered unnecessary during the operation phase.
4.12.1
A
construction noise assessment has been undertaken to predict the noise levels
at the representative NSRs due to the construction of the Project. Practicable mitigation measures, including
use of quiet construction plant / quiet construction method, temporary noise
barriers and good site practices, have been recommended. With the implementation of the recommended
mitigation measures, the predicted construction noise levels at all NSRs comply
with the noise criteria during the
daytime period. Therefore, no noise
impact is expected to arise from the construction activities. Also, no cumulative impact or residual impact
is anticipated. Regular noise monitoring
at NSRs as part of the EM&A programme during the construction stage is
recommended.
4.12.2
Potential
noise impact from the operation of the expanded STKSTW and TSTP has been
assessed. The predicted fixed plant
noise levels at the representative NSRs due to the operation of the expanded STKSTW
and TSTP are well within the relevant
noise criteria.
[1] “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
)