Stage 2 works are assessed in accordance with the
following relevant environmental legislations, guidelines and references:
* Study Brief for EIA study for
Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 2;
* Hong Kong Planning Standards and Guidelines (HKPSG)[21];
* Air Pollution Control Ordinance (APCO)[2];
* Air Pollution Control (Construction Dust) Regulation[5].
6.1.1
Construction Dust Regulation
For construction dust impact, reference should be made to
the Air Pollution Control (Construction Dust) Regulation, TM-EIAO and EPD
Pollution Control Clauses for Construction Contract[3]. An hourly averaged Total Suspended
Particulate (TSP) concentration of 500µg/m3measured at 298K and 101.325kPa should
not be exceeded.
EPD has been
conducting TSP (dust) monitoring in Yuen Long area for several years using High
Volume Samplers. The recent monitoring results for Year 2000 show the annual
average TSP concentration at 95µg/m3 and the 24-hour average at 288
µg/m3. Both results exceeded
the annual AQOs of 80µg/m3 and 24-hour AQO of 260µg/m3,
respectively[2].
ASRs are identified in
accordance with TM-EIAO. The worst
affected ASRs during the construction phase of the proposed works have been
considered. The landuses in the
vicinity of the proposed works include schools and residential developments. The locations of ASRs are shown in Figures
6.1 to 6.3, and a comprehensive list of the key representative ASRs for
construction dust review in Appendix 6.1.
In general, construction
dust sources will be generated from the following activities:
·
Materials handling;
·
Wind erosion of stockpiles;
·
Truck movements on any unpaved road;
·
Excavation and backfilling of soil for site formation and trenching;
·
Stockpiling of excavated materials;
·
Foundation works for Sewage Pumping Station (SPS)
·
Civil construction and E&M installation of SPS
Based on the latest information from studies
of nearby projects, active areas of these sites will be small. In
addition, the separation from the large-scale active construction projects
are far away and proper mitigation measures had
been proposed in their EIA studies, as a
result, miminal cumulative impact from the nearby construction works is
therefore anticipated. Respective
project specific EM&A manual and monitoring requirements had been
stipulated for these major infrastructure projects. The respective Contractor will be responsible for the ultimate
construction method and construction plants, proper mitigation measures and
event/action plan for implementation of the effectiveness of dust control
measurement. With the continual
monitoring and review of dust impact in the area, cumulative impact would not
be anticipated.
Similar to the
previous EIA report (Designated Project) on CE31/99 “Yuen Long and Kam Tin Sewerage and
Sewage Disposal Stage 1”, the sewer and rising mains will be constructed in 50m
segments. With such small scale of construction works, the potential dust
impact would be limited and short term in nature. Regarding the sewage pumping stations, most part of the structures will
be constructed underground while the pumping station building will be about
1-storey above ground level. Similar to
other pumping stations in HK, the sizes of SPS are relatively small (except
YLEPS – but with a great setback distance to ASR). Scaffolding with effective
dust screens, sheeting or netting and automatic water spraying equipment shall
be erected around the perimeter of the building during construction. It is anticipated that the enclosed
scaffolding can effectively minimize dust impact from the pumping station. All the construction works are controlled under the Air Pollution Control
(Construction Dust) Regulation [5], and appropriate pollution
control clauses will be implemented in the contract documentation. With good
site practices and proper precautionary measures, dust impact would be maintained within the criteria.
With the
implementation of the following the procedures and requirements given in the
Air Pollution Control (Construction Dust) Regulation, the potential dust impact
can be reduced to acceptable level:
·
The work programme will be staggered and the active work area will be
limited to 50m segments in order to avoid cumulative impact from any nearby
concurrent construction site;
·
Where a scaffolding is erected around the perimeter of a building under
construction, effective dust screens, sheeting or netting should be provided to
enclose the scaffolding from the ground floor level of the pumping station;
·
Automatic waterspraying system should be provided on the top of the
building structure/scaffolding of SPS if there is nearby sensitive receivers
within 15m;
·
Use of side enclosure and covering of any aggregate or dusty material
storage to reduce emission. Where it is
impracticable owing to frequent access and usage, watering should be adopted to
reduce the fugitive emission. Open stockpiles should be avoided, covered or
placed far away from sensitive receivers;
·
Use of movable wind shield close to the site and air sensitive receiver;
·
Every vehicle should be washed to remove any dusty materials from its
body and wheels immediately before leaving a construction site;
·
Use of speed control for vehicles on dusty site area.
·
All dusty materials on the transport vehicle should be covered entirely
with tarpaulin to ensure that the dusty materials do not disperse from the
vehicle;
·
Water should be continuously sprayed on the surface at where mechanical
breaking operation that causes dust emission is being carried out, unless the
process is accompanied by the operation of an effective dust extraction and
filtering device;
·
The working area of excavation should be sprayed with water immediately
before, during and immediately after the operation so as to maintain the entire
surface wet; and
·
To exercise an effective EM&A monitoring works in order to ensure
the dust suppression measures are effective, and that the event action plan is
properly executed.
Sewage will be transferred within an enclosed system, and
there is no pollution source from the operation of sewers and rising mains.
Odour impact would be a potential concern for Sewage
Pumping Stations (SPS). For Designated
Elements, an odour level criterion of 5 OU applies to Air Sensitive Receiver (ASR)in
accordance with Annex 4 of TM-EIAO[4]. The odour level criterion at ASR is assessed on a 5-second
averaging time.
There is no EPD odour monitoring stations and background information is not available. In addition, it
is understood that there is currently no odour-monitoring programme on the
existing SPS and STWs within the study area; therefore, ambient data and
cumulative impact information are not available.
Representative ASRs
within 500m from the improvement works were identified. The assessment will focus on the nearest
ASRs that may be affected by the proposed works. With regard to the EIA, the focus will be on the odour impact
during operational phase.
Representative Air Sensitive Receivers (ASR) for the existing and future
planned use will be selected to assess the worst-case scenario (Figures 6.1 to 6.3). A summary of these ASRs is given Appendix 7.2.
Septicity in a
sewerage system will result from the activity of bacteria, growing in sewage
and on submerged surfaces which, under anaerobic conditions, reduce
sulphur-containing organic compounds and sulphates to form sulphides and other
malodorous sulphur compounds. This situation will occur where there is
inadequate ventilation and sewage re-aeration to prevent anaerobic conditions
developing, and is frequently found when completely-filled sewers out of
contact with the atmosphere are being pumped up. Prevention of septicity can be achieved by maintaining aerobic
conditions by aeration, oxygenation or addition of nitrates. Provision of oxygen (dissolved or as nitrate)
will satisfy BOD and result in partial treatment of sewage which may have a
significant economic benefit on the subsequent cost of sewage treatment at the
receiving works.
Lack of adequate
ventilation, low velocity of sewage in small diameter rising mains, and high
temperature and BOD of sewage, will inevitably result in septicity which in
turns cause odour nuisance where septic sewage is exposed to the atmosphere.
Septicity can be
contained or prevented by the following:
·
An adequate supply of oxygen (either dissolved or chemically available
as nitrate or peroxide);
·
The use of metal cations (such as iron salts) to precipitate sulphide;
·
Deodorizing vented air through suitable filters;
·
The use of protective coatings applied during construction of concrete
structures; or
·
Providing adequate ventilation to reduce humidity and to achieve
dilution; and
·
Using corrosion-resistant materials for construction of sewers, manholes
and fittings.
In the context of this
EIA study, the EIAO study brief stipulates control of odour impact to the
nearby environment. The enclosures and the provision of suitable odour removal
filters, as mitigation measures are carefully considered in the
assessment. The engineering design is
taken up by DSD.
The potential sources
of odour impact during operation of SPS are as follows:
·
Wet wells; and
·
Screening collection areas.
Screenings will be
removed from the pumping stations throughout operation and maintenance. A
removal frequency of 1-2 times per week is common but otherwise dependent upon
the quantity of screenings collected during the initial period of
operation. Also, under typical
operational procedure, these screenings will be stored and transported in a
covered container, and the transfer process will be confined within the pump
house. Similar to general
refuse, screenings will be transported and disposed of by licensed
collector. Since the SPS building
structure is enclosed, the generation rate of screening will be small with the
provisions of a mechanical ventilating system, odour impact from screening will not be significant.
Air relief valves will be installed along the
rising mains. These valves will be
placed inside manholes at underground confined spaces. Covers of manholes will be constructed of
heavy-duty metal and sealed with watertight sealent. Since the air relief valves is designed for safety purposes
during extreme pressure changes, odour release from the valve will be very
small in quantity and temporary in nature.
It is anticipated that the potential odour impact will be insignificant
and can be disregarded in the assessment.
Among the many
potential odour sources within any sewerage system, hydrogen sulphide (H2S)
is the most commonly known and prevalent odorous gas. In this regard the concentration of H2S will be
employed as a representative odour indicator for odour modelling.
The Pomeroy's equation as
stated in the "Design Manual: Odour and Corrosion Control in Sanitary
Sewerage Systems and Treatment Plants (1985), USEPA [80]” will be
adopted:
where
fluxH2S = H2S
emission flux from surface, g/m2-hr
s = slope of the energy
grade line of the stream or total energy head gradient, m/m
u = sewage velocity, m/s
j = proportion of dissolved
sulphide present as H2S. Values of 0.1 at pH 7.8 and 0.06 at pH 8.2
are applied based on the Pomeroy's equation with measured temperature at 35oC
Acidities were measured at pH 7.8 for the discharge treated effluent and pH 8.2 for the inlet raw sewage (worst case information from DSD ver Mar
04).
[DS] = dissolved sulphide
concentration in the wastewater, mg/L.
These parameters were
measured on 22 May 03 and analysed by an accredited laboratory appointed by
YLSTW of DSD. Based on the latest
released statistical data on sewage volume, temperature and sewage nature for
the last year (ver Mar 04), the results including concentration of dissolved
sulphide in the wastewater have been confirmed by DSD as the representative
worst case scenario and is used for the odour assessment. In view of the industrial reform in the last
decade, it is confirmed by DSD that the nature of effluent collected in YLSTW
is mainly domestic in nature for the entire catchment area. With a similar geological condition and
development nature in the New Territories North region, it is estimated that
the sewage strength and nature at the existing YLSTW will be similar to that in
other SPS under study. Based on the
Pomeroy's equation, the dissociated equilibria for hydrogen sulphide in aqueous
solution are also not sensistive to temperature change. Therefore, the measured
dissolved sulphide concentration in YLSTW is considered as the best available
information for the odour assessment of the SPS. These assumptions have been agreed with DSD based on the
long-term operational experience. These
data are listed in Table 7.1 for reference:
Table 7.1: Measured soluble sulphide
concentrations at YLSTW (worst-case of a.m. and p.m. data)
|
Measured locations
|
Dissolved sulphide concentration in wastewater,
mg/L (1)
|
pH (2)
|
|
Inlet works (before the screw pump)
|
0.112
|
8.2
|
|
Final sedimentation tank (connected to the
discharge point)
|
0.026
|
7.8
|
Remark: (1) Measured
temperature at 32 to 35oC
(2) Acidity
of pH 7.8 was measured at outlet treated effluent & 8.2 at inlet raw sewage
(reconfirmed by DSD as worst case during the last year measurement, ver Mar 04)
In order to take account of the dilution effect of the
ventilation system, the following equation is applied (same equation adopted in the CE62/2000,
EIA Study for Upgrading and Expansion of San Wai Sewage Treatment Works and
Expansion of Ha Tsuen Pumping Station):
Concentration of H2S vented from the SPS = (fluxH2S* surface areas of inlet channels and wet
well on plan)/ (total room volume x Air Change Rate)
As recommended in the Sewerage Manual [80] and
subsequently reviewed by DSD in the previous Working Paper, a typical air
change rate of 15ACH is adopted for SPS in the HKSAR.
The volumes and H2S emission fluxes of
wet/submerged well and inlet/screening room of SPS were estimated from
engineering drawings and are shown in Table 7.2.
Table 7.2: Air volumes of various
pumping stations
|
Works
Package
|
Works
Item
|
Location
|
Air
Volume, chamber and well (m3)
|
H2S Emission Rate, µg/s, from chamber
and well (without air ventilation and filters) (2)
|
|
Tin
Shui Wai and San Wai Areas
|
|
2A-1T
|
OP1
|
Pumping station in the
north of YLSTW (Yuen Long Effluent
Pumping Station)
|
5864.2 (1)
|
2.808E+2
|
|
Tin Shui Wai and San Wai Areas
|
|
Alternative
scheme of 2A-1T
|
AP1
|
Pumping station in the
north of YLSTW (Yuen Long Effluent
Pumping Station)
|
5864.2 (1)
|
2.808E+2
|
|
Ngau
Tam Mei and San Tin Areas
|
|
2A-2T
and
2B-1T
|
P1
|
Ngau Tam Mei sewage
pumping station
|
1471.17
|
1.918E+2
|
|
P2
|
Tam Mei Barracks sewage pumping station (Tam Mei
Camp Sewage Pumping Station)
|
696.21
|
3.535E+1
|
|
P3
|
San Tin sewage pumping station
|
1017.45
|
1.268E+2
|
|
P4
|
San Lung Tsuen sewage pumping station
|
753.98
|
3.806E+1
|
|
P5
|
San Tin Barracks sewage pumping station (Cassino
Line Sewage Pumping Station)
|
350.2
|
1.77E+1
|
|
Lau Fau Shan and Mong Tseng Areas
|
|
2A-3T
|
A1
|
Lau Fau Shan sewage pumping station
|
350.2
|
1.77E+1
|
|
A2
|
Mong Tseng sewage pumping station
|
721.68
|
3.652E+1
|
|
Shap Pat Heung Area
|
|
2B-2T
|
B1
|
Shan Ha Tsuen sewage pumping station
|
721.68
|
3.652E+1
|
|
B2
|
Muk Kiu Tau Tsuen sewage pumping station
|
721.68
|
3.652E+1
|
|
B3
|
Sham Chung Tsuen sewage pumping station
|
350.2
|
1.77E+1
|
|
B4
|
Shui Tsiu San Tsuen sewage pumping station
|
350.2
|
1.77E+1
|
|
B5
|
Shung Ching San Tsuen sewage pumping station
|
350.2
|
1.77E+1
|
|
B6
|
Nga Yiu Tau sewage pumping station
|
350.2
|
1.77E+1
|
|
B7
|
Pak Sha Tsuen sewage pumping station
|
350.2
|
1.77E+1
|
Remark: (1) The
functional area of the inlet chambers have been reduced in latest design (Feb
04 version)
(2) H2S
emission rates are estimated based on the latest released operating parameters
from YLSTW (version Feb 04)
As recommended in the “EPD’s Guidelines on Choice of
Models and Model Parameters [81]”, odour dispersion modelling was
undertaken using the ISCST3 model. An
averaging time of 1-hour was adopted as the worst-case scenario assessment. This
1-hr averaged value was then converted to 3-min averaged value in accordance
with a stability dependent power law relationship[12] as follows:
where Xl
= concentration for the longer time averaging time;
Xs
= concentration for the shorter time averaging time;
ts=
shorter averaging time;
tl
= longer averaging time;
P = power
law exponent (Stability Class A: 0.5, B: 0.5, C: 0.333, D: 0.2, E:0.167, F:
0.167)
The 3-min averaged value was then converted to a 5-second
averaged value, in response to the requirement of the odour level criterion.
Reference [13] suggests that typical maximum or peak 5 second averaged
concentrations within any 3-minute period appear to be of the order of 5 times
the 3-min average and during very unstable conditions, larger ratios of perhaps 10:1 are more appropriate. Table
7.3 shows the conversion factors applied to determine the 5-second value under
different stability classes.
Table 7.3: Multiplying factors
for odour assessment
|
Atmospheric
Stability Class
|
Conversion
Factor from 1 hour to 3 min
|
Conversion
Factor from 3 min to 5s
|
Overall
Conversion from 1 hr to 5s
|
|
A
|
4.47
|
10
|
44.7
|
|
B
|
4.47
|
10
|
44.7
|
|
C
|
2.71
|
5
|
13.6
|
|
D
|
1.82
|
5
|
9.1
|
|
E
|
1.65
|
5
|
8.25
|
|
F
|
1.65
|
5
|
8.25
|
The USEPA regulatory default settings were selected for
the model runs. The rural mode dispersion option was adopted to take account of
the topography of the study area. Each
SPS is assumed a point source location with the exhaust height taken at its
roof. Typical exhaust velocities are
estimated from similar existing SPS. The exhaust
lourve areas and velocities of various SPS are listed in Table 7.4. Wind data from the nearest weather
station, Lau Fau Shan Automatic Weather Station and mixing height data from
King’s Park weather station were considered the best available data set for the
analysis. A continuous 3-year
meteorological data sets from Yr 1999 to 2001 have been adopted for assessment
following examples of other DSD studies including EIA study for Wan Chai East
and North Point Sewerage and EIA study for Ngong Ping Sewage Treatment Works
and Sewerage.
Table 7.4: Exhaust grille areas and
exhaust velocities of various pumping stations (inlet and wet well)
|
Works
Package
|
Works
Item
|
Location
|
Exhaust Air Volume of inlet and wetwell with
15ACH (m3/s)
|
Total Exhaust Grille Area/ Stack diameter
(1) (m2)
|
Exhaust Vel
(m/s) (2) / Stack Height (3) (m)
|
|
Tin
Shui Wai and San Wai Areas
|
|
2A-1T
|
OP1
|
Pumping station in the
north of YLSTW (Yuen Long Effluent
Pumping Station)
|
24.434 (4)
|
3.054 / 1.972
|
8 / 8
|
|
Tin
Shui Wai and San Wai Areas
|
|
Alternative
scheme of 2A-1T
|
AP1
|
Pumping station in the
north of YLSTW (Yuen Long Effluent
Pumping Station)
|
24.434 (4)
|
3.054 / 1.972
|
8 / 8
|
|
Ngau
Tam Mei and San Tin Areas
|
|
2A-2T
and
2B-1T
|
P1
|
Ngau Tam Mei sewage
pumping station
|
6.130
|
0.766 / 0.988
|
8 / 8
|
|
P2
|
Tam Mei Barracks sewage pumping station (Tam Mei
Camp Sewage Pumping Station)
|
2.901
|
0.363 / 0.679
|
8 / 4.1
|
|
P3
|
San Tin sewage pumping station
|
4.239
|
0.530 / 0.821
|
8 / 7
|
|
P4
|
San Lung Tsuen sewage pumping station
|
3.142
|
0.393 / 0.707
|
8 / 4.1
|
|
P5
|
San Tin Barracks sewage pumping station (Cassino
Line Sewage Pumping Station)
|
1.459
|
0.182 / 0.482
|
8 / 4.1
|
|
Lau Fau Shan and Mong Tseng Areas
|
|
2A-3T
|
A1
|
Lau Fau Shan sewage pumping station
|
1.459
|
0.182 / 0.482
|
8 / 4.1
|
|
A2
|
Mong Tseng sewage pumping station
|
3.007
|
0.376 / 0.692
|
8 / 4.1
|
|
Shap Pat Heung Area
|
|
2B-2T
|
B1
|
Shan Ha Tsuen sewage pumping station
|
3.007
|
0.376 / 0.692
|
8 / 4.1
|
|
B2
|
Muk Kiu Tau Tsuen sewage pumping station
|
3.007
|
0.376 / 0.692
|
8 / 4.1
|
|
B3
|
Sham Chung Tsuen sewage pumping station
|
1.459
|
0.182 / 0.482
|
8 / 4.1
|
|
B4
|
Shui Tsiu San Tsuen sewage pumping station
|
1.459
|
0.182 / 0.482
|
8 / 4.1
|
|
B5
|
Shung Ching San Tsuen sewage pumping station
|
1.459
|
0.182 / 0.482
|
8 / 4.1
|
|
B6
|
Nga Yiu Tau sewage pumping station
|
1.459
|
0.182 / 0.482
|
8 / 4.1
|
|
B7
|
Pak Sha Tsuen sewage pumping station
|
1.459
|
0.182 / 0.482
|
8 / 4.1
|
Remark: (1) Assuming point
source in the ISCST model (Circular stack area)
(2)
Exhaust air vel of 8m/s as extracted from similar pumping station at Ha Tsuen
PS
(3)
The emission stack is assumed to be on the roof of the pumping station
(4) The
functional area of the inlet chambers have been reduced in latest design (Feb
04 version)
Assessments were conducted at 1.5m, 5m, 10m, 15m, 20m,25m and 30m
(40m for the 2A-1T package) above ground. Contours were produced at the level of maximum concentration
during the worst-case year.
In accordance with the “Environmental Guidance Note for
Sewage Pumping Station which is Not a Designated Project, EPD[14]”,
an established odour threshold correlation factor of 1 Odour Unit (OU) is
equivalent to 0.66µg/m3 H2S for conversion.
YLEPS will convey
treated effluent with minimal odourous substances, and the setback distance
from the nearest ASR is more than 400m.
Since a standard odour removal filter system with an efficiency of not
less than 99.5% will also be adopted, contribution from the pumping station is
minimal. Direct comparision has been
made with other SPS conveying odourous raw sewage with far less setback distance
(less than 100m) to the ASR, provision of such standard odour removel filter
has been proven to be an effective precaustionary measures. No odour impact was anticipated even for ASR
with much shorter setback distance. These examples included Designated Projects
of Yuen Long South SPS and Au Tau SPS.
Based on the
survey record, there is no major STW within 500m from P1 pumping station, and
therefore, the cumulative impact will be minimal.
It was understood
from DSD that except for Tam Mei Barrack STW and Yuen Long South SPS, there was
no other sewage treatment plant and pumping station within 500m of the pumping
stations of this project. Several site
inspections conducted between April 2002 and Jan 2003 also confirmed the same.
Table 7.5 provides a summary of potential cumulative background sources to the
sewage pumping station.
Table
7.5:
Cumulative background sources
|
Works Package
|
Works Item
|
Location
|
Remark
|
|
Tin Shui Wai and San Wai Areas
|
|
2A-1T
|
OP1
|
Yuen Long Effluent
Pumping Station (Designated
Element)
|
The YLEPS is not a potential odour source since treated sewer will be
conveyed and the nearest ASR is mor e than 400m away.
|
|
Tin Shui Wai and San Wai Areas
|
|
Alternative scheme of 2A-1T
|
AP1
|
Yuen Long Effluent
Pumping Station (Designated
Element)
|
The YLEPS is not a potential odour source since treated sewer will be
conveyed and the nearest ASR is mor e than 400m away.
|
|
Ngau Tam Mei and San Tin Areas
|
|
2A-2T
and
2B-1T
|
P1
|
Ngau Tam Mei
sewage pumping station(Designated
Element)
|
No cumulative
source, 0 OU cumulative background
|
|
P2
|
Tam Mei Barracks sewage pumping station (Tam Mei Camp
Sewage Pumping Station)
|
Cumulative source: Tam Mei Barracks STW serves only a small number of
PRC soldiers, and there is a future plan to phase out this STW. Cumulative impact, if any would be minor and
short term [1]
|
|
P3
|
San Tin sewage pumping station
|
No cumulative
source, 0 OU cumulative background
|
|
P4
|
San Lung Tsuen sewage pumping station
|
No cumulative
source, 0 OU cumulative background
|
|
P5
|
San Tin Barracks sewage pumping station (Cassino Line
Sewage Pumping Station)
|
No cumulative
source, 0 OU cumulative background
|
|
Lau Fau Shan and Mong Tseng Areas
|
|
2A-3T
|
A1
|
Lau Fau Shan sewage pumping station
|
No cumulative
source, 0 OU cumulative background
|
|
A2
|
Mong Tseng sewage pumping station
|
No cumulative
source, 0 OU cumulative background
|
|
Shap Pat Heung Area
|
|
2B-2T
|
B1
|
Shan Ha Tsuen sewage pumping station
|
Cumulative source: Yuen Long South SPS, cumulative background has been incorporated [2]
|
|
|
B2
|
Muk Kiu Tau Tsuen sewage pumping station
|
Cumulative source: Yuen Long South SPS, cumulative background has been incorporated [2]
|
|
|
B3
|
Sham Chung Tsuen sewage pumping station
|
Cumulative source: Yuen Long South SPS, cumulative background has been incorporated [2]
|
|
|
B4
|
Shui Tsiu San Tsuen sewage pumping station
|
Cumulative source: Yuen Long South SPS, cumulative background
has been incorporated[2]
|
|
|
B5
|
Shung Ching San Tsuen sewage pumping station
|
Cumulative source: Yuen Long South SPS, cumulative background
has been incorporated[2]
|
|
|
B6
|
Nga Yiu Tau sewage pumping station
|
Cumulative source: Yuen Long South SPS, cumulative background
has been incorporated[2]
|
|
2B-2T
|
B7
|
Pak Sha Tsuen sewage pumping station
|
Cumulative source: Yuen Long South SPS, cumulative background has been incorporated [2]
|
Remark: [1] DSD advised that there is a long term plan to divert the sewage from
Tam Mei Barrack to YLSTW. In future, Tam Mei Barracks STW will be
decommissioned and any cumulative odour impact would be minor and short term.
[2] A filtering system with a H2S
removal efficiency of not less than 99.5% has been incorporated in the DSD
specification for the Yuen Long South SPS. (Appendix 7.2)
Assessments have been conducted for Yr 1999 to Yr 2001 and
Yr 2001 is identified as the worst-case scenario. The emission rate
calculation sheet is attached in Appendix 7.3 for reference. Detailed
results are given in Appendix 7.4. Based on the assessment findings, the
required odour removal efficiency is recommended to minimize any potential impact
on the ASRs. Odour contours are presented for the general dispersion pattern.
7.9.1 Tin Shui Wai and San Wai Areas (Alternative 2A-1T)
The YLEPS
(OP1/AP1) is designed to convey the treated effluent (effluent with minimal
odourous substances) to the San Wai STW.
In addition, the distance from the nearest sensitive receiver to YLEPS
is more than 400m. With the provision
of the best available odour filter with a removal efficient of not less than
99.5%, the maximum odour concentration would be reduced to 0.016OU which
represents only 0.3% of the criterion.
This small level of odour is hard to detect by human nose. The odour contour for the YLEPS at the
nearest ASR under the worst-case scenario (25m above ground level) is presented
in Figure 7.1.
Comparison had
also been made with other Designated Projects on SPS conveying odourous raw
sewage, and the odour level at 400m was insignificant with the provision of the
same standard odour removal filter. Therefore, these findings have reconfirmed
that the odour discharge from YLEPS is insignificant, and therefore concluded
YLEPS is not a potential odour source.
7.9.2 Ngau Tam Mei and San Tin Areas (2A-2T and 2B-1T)
Results indicated
that the odour concentrations at some ASRs would exceed the odour criterion
under the “Without odour control measures” scenario. Therefore, odour removal filtering system with not less than
99.5% H2S removal efficient will be included as a control
measure. This type of filtering system
has been adopted in some planned SPS, such as Yuen Long South SPS. With this measure, the maximum odour
concentration at the ASRs would be reduced to 0.093OU which is 1.9% of the
criterion. The odour contour for
worst-case scenario (20m above ground level) is presented in Figures 7.2a to
7.2e.
7.9.3 Lau Fau Shan and Mong Tsuen Areas (2A-3T)
Results indicated
that the odour concentrations at some ASRs would exceed the odour criterion
under the “Without odour control measures” scenario. Therefore, odour removal filtering system with not less than 95%
H2S removal efficient will be included as a control measure. This type of filtering system has been
commonly adopted in existing SPS. With
this measure, the maximum odour concentration at the ASRs would be reduced to
0.32OU which is 6.4% of the criterion.
The odour contour for the worst-case scenario (20m above local ground)
is presents in Figures 7.3a & 7.3b.
7.9.4 Shap Pat Heung Area (2B-2T)
Results indicated
that there would be potential exceedance of odour impact at some representative
ASRs under the “Without odour control measures” scenario. Therefore, odour
removal filtering system with not less than 95% H2S removal
efficient will be included as a control measure. This type of filtering system has been commonly adopted in
existing SPS. With this measure, the
maximum odour concentration at the ASRs would be reduced to 0.504OU which is
10.1% of the criterion including cumulative background odour level from Yuen
Long South PS. The odour contour for
the worst-case scenario (15m above ground level) is presented in Figures 7.4a
to 7.4g.
During
operational phase, temporary odour nuisance as a result of pumping station
failure, repairing and maintenance of pressurized sewers may be
experienced. Under these circumstances,
raw sewer will be overflown from the emergency discharge and enters the nearby
water body where ASRs are identified.
The following precautionary measures are recommended to minimize the
potential odour impact:
·
Hand-cleaned screens should be provided at the overflow bypass to
prevent the discharge of floating solids into receiving water bodies;
·
In case the weather condition is very stagnant with very low dispersion
effect, deodorization with oxidants, such as sodium hydroxide, chlorine
solution and sodium hypochlorite can be considered to oxidize the odorous
chemicals;
·
Standby pump and sewers/rising mains should be provided to facilitate
maintenance and repairing of equipment; and
·
Sewage pumping vehicles/tankers could be deployed to divert some of the
effluent to the nearby STW/SPS.
The following odour
precautionary measures should be implemented as far as possible during
operation of SPS:
·
The entire SPS; especially wet wells and screening collection areas
should be enclosed in a building structure (Similar to that shown in Figure
14.62 of the EIA report);
·
Discharge point of the odour removal system should be directed away from
the adjacent sensitive uses, and the discharge height should not be less than
those assumed in Table 7.4;
·
Screened material from SPS should be stored in a covered container;
·
The transportation of screened material during maintenance should be
transported in an enclosed type vehicle and disposed off on the same working
day;
·
Checking and maintenance of the odour removal system should be
implemented at least once every half year to maintain the removal efficiency;
and
·
Odour removal systems, e.g activated carbon filters, should be provided
to reduce the odour emissions.
Filtering systems with an H2S removal efficiency:
·
of not less than 99.5% for the YLEPS (OP1/AP1) (where OP1/AP1 is a D.E.)
;
·
of not less than 99.5% for all SPS at 2A-2T and 2B-1T (P1 to P5) (where
P1 is a D.E);
·
of not less than 95% for all SPS at 2A-3T (A1 to A2); and
·
of not less than 95% for all SPS at 2B-2T (B1 to B7).
Control over the generation of construction noise in Hong
Kong is governed by the Noise Control Ordinance (NCO)[6] (Cap 400)
and its subsidiary requirements.
Various Technical Memoranda (TMs) have been issued under the NCO to
stipulate control approaches and criteria.
These TMs prescribe the maximum permitted noise levels for the use of
Powered Mechanical Equipment (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 applicable TMs to the
control of noise from construction activities in the current proposed works
are:
* Technical Memorandum on Environmental Impact Assessment Process
(TM-EIAO)[1]
* Technical Memorandum on Noise from Construction Work other than
Percussive Piling (TM-CW)[7];
* Technical Memorandum on Noise from Construction Work in Designated
Areas (TM-DA) [8]; and
* Technical Memorandum on Noise from Percussive Piling (TM-PP) [9].
8.1.1 Noise Standards for Normal Working Hours
Assessments of construction noise impacts shall make
reference to Annex 13 of TM-EIAO[4]. The daytime noise limits for construction works as stipulated in
Annex 5 of TM-EIAO are given in Table 8.1 below.
Table
8.1: Noise standards for daytime (0700 to 1900 hours) construction
activities
Uses
|
Acceptable Noise Standards
Leq (30mins), dB(A)
|
|
All domestic premises including temporary housing
accommodation
|
75
|
|
Hotels and hostels
|
75
|
|
Educational institutions including kindergartens,
nurseries and all others where unaided voice communication is required
|
70
65 (During examinations)
|
Note: The above standards apply to uses which rely on
open windows for ventilation.
The noise criteria as laid down in Table 8.1 for the
construction of the project shall be met as far as practicable. All practicable mitigation measures should
be exhausted and the residual impacts should be minimized.
For the control of percussive piling, noise criteria shall
make reference to TM-PP for determining the permitted hours of operation which
depend upon the predicted noise levels at the worst affected NSR.
8.1.2 Noise Standards for Restricted Hours
The NCO provides statutory controls on general
construction works during the restricted hours (ie 1900 to 0700 hours from
Monday to Saturday and at any time on Sundays or public holidays). The use of PME for construction works during
the restricted hours would require a CNP.
The TM-CW details the procedures adopted by EPD for assessing such
application. The granting of a CNP is
subject to conditions stated in the permit and it may be revoked at any time
for failure to comply with the stated conditions.
Areas in Tin Shui Wai, Wan Chau and Mai Po are classified
as Designated Area as defined in the Noise Control Designated Area Plan
no. EPD/NP/NT-04a. Maximum noise levels due to the Specific
Powered Mechanical Equipment (SPME) from construction activities during the restricted
hours at affected NSRs are controlled under the TM-DA and shall not exceed the
specified Acceptable Noise Levels (ANLs).
These ANLs are stipulated in accordance with the Area Sensitivity
Ratings (ASR) established for the NSRs.
The corresponding Basic Noise Levels (BNLs) are stated in Table 8.2
below.
Table 8.2:BNLs for
construction noise other than percussive piling in designated area under NCO
Time Period
|
Area Sensitivity Ratings
|
|
A
|
B
|
C
|
|
All weekdays during the evening (1900 to 2300 hours), and
general holidays (including Sundays) during the day and evening (0700 to 2300
hours)
|
45
|
50
|
55
|
|
All days during the night-time (2300 to 0700 hours)
|
30
|
35
|
40
|
For those areas, which are not classified as
non-designated area, the noise limits are listed in Table 8.3.
Table
8.3: BNLs for construction noise other than percussive piling in
non-designated area under NCO
Time Period
|
Area Sensitivity Ratings
|
|
A
|
B
|
C
|
|
All
weekdays during the evening (1900 to 2300 hours), and general holidays
(including Sundays) during the day and evening (0700 to 2300 hours)
|
60
|
65
|
70
|
|
All
days during the night-time (2300 to 0700 hours)
|
45
|
50
|
55
|
Despite any description or assessment made in this report
on construction noise aspects, there is no guarantee that a CNP will be issued
for the project construction. The
Noise Control Authority will consider a well-justified CNP application, once
filed, for construction works within restricted hours as guided by the relevant
Technical Memoranda issued under the Noise Control Ordinance. The Noise Control Authority will take into
account contemporary conditions/situations of adjoining land uses and any
previous complaints against construction activities at the site before making
the decision in granting a CNP. Nothing
in this Report shall bind the Noise Control Authority in making his
decision. If a CNP is to be issued, the
Noise Control Authority shall include in it any condition he thinks fit. Failure to comply with any such conditions
will lead to cancellation of the CNP and prosecution action under the NCO.
The Project involves the construction of a trunk sewerage
system with 4 sections of sewers/rising mains and 15 pumping stations. The Project will be located in the sub-urban
areas of Yuen Long and Kam Tin.
According to the proposed sewer alignments and locations of Sewage
Pumping Stations, most of the proposed sewers/rising mains will be laid along
existing paved roads with the proposed pumping stations located nearby.
The areas, except for Tin Shui Wai, are generally rural in
nature and with scattered residential developments, villages and open storage
sites. For Tin Shui Wai, the area
consists of several public and private estates. Most of the buildings are high-rise.
During the construction periods from mid 2005 to late 2007, different
interfacing projects are identified and they are summarized in Table 8.3a –
8.3d. For ease of reference, the setback distance and construction programme have been provided for genuine concurrent projects
only (ie. Both within the study limit and
constructed at the same time as the current project).
|
Item
|
Concurrent Project
|
Scheduled Construction Period
|
Overlapping Months
|
Distance
> 300m from first layer NSR
|
Potential to Cause Cumulative Noise Impact
|
|
Start
|
Complete
|
|
1
|
DD901 – West Rail Environmental Support
Services Essential Public Infrastructure Works: Yuen Long, Tin Shui Wai and
Tuen Mun Centre
|
May 99
|
Nov 03
|
0
|
Yes
|
û
|
|
2
|
Tin Shui Wai Phase 4 Extension
|
2001
|
2004
|
0
|
No
|
û
|
|
3
|
Light Rail Transit (LRT) Extension in Tin
Shui Wai Reserve Zone and Grade Separation of the LRT with Pui To Road and
Tsing Lung Road in Tuen Mun
|
2001
|
2004
|
0
|
No
|
û
|
|
4
|
Widening of Yuen Long Highway between Lam Tei
and Shap Pat Heung Interchange
|
Aug 2003
|
Dec 2005
|
6
|
Yes
|
û
|
|
5
|
Yuen Long Bypass Floodway - Feasibility
Study
|
Mar 2001
|
Dec 2003
|
0
|
Yes
|
û
|
|
6
|
Deep Bay Link (San Wai Section)
|
Jul 2003
|
Jun 2006
|
12
|
No
|
ü
|
|
7
|
San Wai Sewerage Treatment Works
|
2004
|
2007
|
30
|
No
|
ü
|
|
8
|
Shenzhen Western Corridor
|
Mar 2003
|
Dec 2005
|
6
|
Yes
|
û
|
|
9
|
Ping Ha Road Improvement Remaining Works
|
---
|
2006
|
6
|
No
|
ü
|
|
10
|
Alternative 4 Bypass Culvert
|
2003
|
2007
|
18
|
No
|
ü
|
|
11
|
Main Drainage Channels and Poldered Village
Protection Schemes for San Tin[1]
|
Jun 2001
|
Dec 2003
|
0
|
Yes
|
û
|
|
12
|
Yuen Long and Kam Tin Sewerage and Sewage
Disposal Stage 1 (1B-2T)
|
Aug 2004
|
Feb 2008
|
30
|
No
|
ü
|
|
13
|
Tin Shui Wai Further Development
|
July 1998
|
2003
|
0
|
Yes
|
û
|
|
14
|
157DS Phase 3B/3C San Wai and Tung Tau
Tsuen
|
June 2005
|
June 2007
|
24
|
No
|
ü
|
|
15
|
Lau Fau Shan Remaining Development
|
No construction schedule
|
---
|
Yes
|
û
|
Note [1] : MDC-Eastern Section is more than 300 m
from the present project
Table 8.3b: Interfacing Projects for Package 2A-3T (Lau Fau Shan Area)
|
Item
|
Concurrent Project
|
Scheduled Construction Period
|
Overlapping Months
|
Distance
> 300m from first layer NSR
|
Potential to Cause Cumulative Noise Impact
|
|
Start
|
Complete
|
|
1
|
DD901 – West Rail Environmental Support
Services Essential Public Infrastructure Works: Yuen Long, Tin Shui Wai and
Tuen Mun Centre
|
May 99
|
Nov 03
|
0
|
Yes
|
û
|
|
2
|
Tin Shui Wai Phase 4 Extension
|
2001
|
2004
|
0
|
Yes
|
û
|
|
3
|
Light Rail Transit (LRT) Extension in Tin
Shui Wai Reserve Zone and Grade Separation of the LRT with Pui To Road and
Tsing Lung Road in Tuen Mun
|
2001
|
2004
|
0
|
Yes
|
û
|
|
4
|
Widening of Yuen Long Highway between Lam
Tei and Shap Pat Heung Interchange
|
Aug 2003
|
Dec 2005
|
6
|
Yes
|
û
|
|
5
|
Yuen Long Bypass Floodway - Feasibility
Study
|
Mar 2001
|
Dec 2003
|
0
|
Yes
|
û
|
|
6
|
Deep Bay Link
|
Jul 2003
|
Jun 2006
|
12
|
Yes
|
û
|
|
7
|
San Wai Sewerage Treatment Works
|
2004
|
2007
|
30
|
Yes
|
û
|
|
8
|
Shenzhen Western Corridor
|
Mar 2003
|
Dec 2005
|
6
|
Yes
|
û
|
|
9
|
Ping Ha Road Improvement Remaining Works
|
---
|
2006
|
6
|
No
|
ü
|
|
10
|
Alternative 4 Bypass Culvert
|
2003
|
2007
|
18
|
Yes
|
û
|
|
11
|
Main Drainage Channels and Poldered Village
Protection Schemes for San Tin[1]
|
Jun 2001
|
Dec 2003
|
0
|
Yes
|
û
|
|
12
|
Yuen Long and Kam Tin Sewerage and Sewage
Disposal Stage 1 (1B-2T)
|
Aug 2004
|
Feb 2008
|
30
|
Yes
|
û
|
|
13
|
Tin Shui Wai Further Development
|
July 1998
|
2003
|
0
|
No
|
û
|
|
14
|
157DS Phase 3B/3C San Wai and Tung Tau
Tsuen
|
June 2005
|
June 2007
|
24
|
Yes
|
û
|
|
15
|
Lau Fau Shan Remaining Development
|
No construction schedule
|
---
|
No
|
û
|
|
|
|
|
|
|
|
|
|
Note [1] :
MDC-Eastern Section is more than 300 m from the present project
Table 8.3c: Interfacing Projects for Package 2B-2T (Shap Pat Heung Area)
|
Item
|
Concurrent Project
|
Scheduled Construction Period
|
Overlapping Months
|
Distance > 300m from first layer NSR
|
Potential to Cause Cumulative Noise Impact
|
|
Start
|
Complete
|
|
1
|
DD901 – West Rail Environmental Support
Services Essential Public Infrastructure Works: Yuen Long, Tin Shui Wai and
Tuen Mun Centre
|
May 99
|
Nov 03
|
0
|
Yes
|
û
|
|
2
|
Tin Shui Wai Phase 4 Extension
|
2001
|
2004
|
0
|
Yes
|
û
|
|
3
|
Light Rail Transit (LRT) Extension in Tin
Shui Wai Reserve Zone and Grade Separation of the LRT with Pui To Road and
Tsing Lung Road in Tuen Mun
|
2001
|
2004
|
0
|
Yes
|
û
|
|
4
|
Widening of Yuen Long Highway between Lam
Tei and Shap Pat Heung Interchange
|
Aug 2003
|
Dec 2005
|
6
|
No
|
ü
|
|
5
|
Yuen Long Bypass Floodway - Feasibility
Study
|
Mar 2001
|
Dec 2003
|
0
|
No
|
û
|
|
6
|
Deep Bay Link
|
Jul 2003
|
Jun 2006
|
12
|
Yes
|
û
|
|
7
|
San Wai Sewerage Treatment Works
|
2004
|
2007
|
30
|
Yes
|
û
|
|
8
|
Shenzhen Western Corridor
|
Mar 2003
|
Dec 2005
|
6
|
Yes
|
û
|
|
9
|
Ping Ha Road Improvement Remaining Works
|
---
|
2006
|
6
|
Yes
|
û
|
|
10
|
Main Drainage Channels and Poldered Village
Protection Schemes for San Tin[1]
|
Jun 2001
|
Dec 2003
|
0
|
Yes
|
û
|
|
11
|
Yuen Long and Kam Tin Sewerage and Sewage
Disposal Stage 1 (1A-1T)
|
Aug 2003
|
Feb 2006
|
8
|
Yes
|
û
|
|
12
|
Tin Shui Wai Further Development
|
July 1998
|
2003
|
0
|
Yes
|
û
|
|
13
|
157DS Phase 2 Yuen Long South Pumping
Station, Rising Main to Castle Peak Road and Sewers
|
Jan 2003
|
May 2006
|
12
|
No
|
ü
|
|
14
|
274DS Phase 1 Shap Pat Heung Rising Main
and Gravity Sewer; Au Tau Sewage Pumping Station and Ancillary Works
|
Jan 2003
|
May 2006
|
12
|
No
|
ü
|
|
15
|
274DS Phase 7A/ 7B San Sang Tsuen and Tin
Sum, Shan Ha and Tai Tong Tsuen
|
June 2007
|
July 2009
|
6
|
No
|
ü
|
|
16
|
Lau Fau Shan Remaining Development
|
No construction schedule
|
---
|
Yes
|
û
|
|
|
|
|
|
|
|
|
|
|
Note [1]: MDC-Eastern Section is
more than 300 m from the present project
Table 8.3d: Interfacing Projects for Package 2A-2T and 2B-1T (Ngau Tam Mei Area)
|
Item
|
Concurrent Project
|
Scheduled Construction Period
|
Overlapping Months
|
Distance
> 300m from first layer NSR
|
Potential to Cause Cumulative Noise Impact
|
|
Start
|
Complete
|
|
1
|
DD901 – West Rail Environmental Support
Services Essential Public Infrastructure Works: Yuen Long, Tin Shui Wai and
Tuen Mun Centre
|
May 99
|
Nov 03
|
0
|
Yes
|
û
|
|
2
|
Tin Shui Wai Phase 4 Extension
|
2001
|
2004
|
0
|
Yes
|
û
|
|
3
|
Light Rail Transit (LRT) Extension in Tin
Shui Wai Reserve Zone and Grade Separation of the LRT with Pui To Road and
Tsing Lung Road in Tuen Mun
|
2001
|
2004
|
0
|
Yes
|
û
|
|
4
|
Widening of Yuen Long Highway between Lam
Tei and Shap Pat Heung Interchange
|
Aug 2003
|
Dec 2005
|
6
|
Yes
|
û
|
|
5
|
Yuen Long Bypass Floodway - Feasibility
Study
|
Mar 2001
|
Dec 2003
|
0
|
Yes
|
û
|
|
6
|
Deep Bay Link
|
Jul 2003
|
Jun 2006
|
12
|
Yes
|
û
|
|
7
|
San Wai Sewerage Treatment Works
|
2004
|
2007
|
30
|
Yes
|
û
|
|
8
|
Shenzhen Western Corridor
|
Mar 2003
|
Dec 2005
|
6
|
Yes
|
û
|
|
9
|
Ping Ha Road Improvement Remaining Works
|
---
|
2006
|
6
|
Yes
|
û
|
|
10
|
Main Drainage Channels and Poldered Village
Protection Schemes for San Tin [1]
|
Jun 2001
|
Dec 2003
|
0
|
Yes
|
û
|
|
11
|
Yuen Long and Kam Tin Sewerage and Sewage
Disposal Stage 1 (1A-1T)
|
Aug 2003
|
Feb 2006
|
8
|
No
|
ü
|
|
12
|
Tin Shui Wai Further Development
|
July 1998
|
2003
|
0
|
Yes
|
û
|
|
13
|
92CD Package NTM1
|
Nov 2003
|
Jun 2006
|
12
|
Yes
|
û
|
|
14
|
Lau Fau Shan Remaining Development
|
No construction schedule
|
---
|
Yes
|
û
|
|
|
|
|
|
|
|
|
|
|
Note [1] : MDC-Eastern Section is more than 300 m from the present project
The land uses in the
vicinity of the proposed works include mainly G/IC and residential developments. The locations of the NSRs are shown in
Figures 8.1 to 8.3. A comprehensive
list of the key representative NSRs for construction noise assessment is listed
in Appendix 8.3.
During
the construction phase of the Project, Power Mechanical Equipment (PME) will be
the major noise sources. Basically, the construction works will involve four
types of activities: the construction of Sewers and Rising Mains using Open
Trench method, the construction of Sewers and Rising Mains across local streams
by Pipe Jacking method, Road Pavement & Finishes and the Construction of
the Pumping Stations.
Gravity sewers and rising mains will be
constructed by open trench method along the existing road. This necessible the
closure of one traffic lane, which will form the workfront for the sewers and
rising mains construction. Sewer construction will be in segments of up to 50m
in length at any one time and each workfront will be separated by a clearance
distance of ~ 600m. Hence, it is expected that the identified NSRs will only be
affected by the construction activities associated with one workfront at any
one time. Pipe jacking method will be adopted where the sewers cross existing
watercourses. For this method, the construction noise will be restricted to the
pit area only.
Cumulative noise impact during the
construction period with the interfacing projects listed in Section 8.3 is
assessed to obtain the maximum noise level at the identified NSRs.
The
construction plant inventory for each type of activities are shown in Table
8.6, which is adopted from the YLKTSSD Stage 1 EIA report. Their corresponding
PME sound power levels are summarized in Appendix 8.1.
Table 8.6: Construction plant inventory
|
Activities
|
Plant
|
TM
ref
|
Unit
|
|
1. Sewers and Rising Mains using Open
Trench Method
|
|
G1. Site Preparation
|
Pilling, oscillator
|
CNP 165
|
1
|
|
Excavator with Mini Attachment
|
CNP 081
|
1
|
|
Breaker, excavator mounted
|
CNP 028
|
1
|
|
G2. Trench excavation and earth work
|
Excavator
|
CNP 081
|
1
|
|
Dump Truck
|
CNP 067
|
2
|
|
Roller / Vibrating Roller
|
CNP 186
|
1
|
|
G3. Finishes
|
Concrete Mixer Truck
|
CNP 044
|
1
|
|
Concrete Poker Vibrator
|
CNP 170
|
1
|
|
Crawler Crane with Concrete Skip
|
CNP 048
|
1
|
|
Flat Bed Lorry
|
CNP 141
|
1
|
|
Generator
|
CNP 101
|
1
|
|
2. Sewer and Rising Mains using the Pipe
Jacking Methods at crossing streams
|
|
G1. Site Preparation
|
Air Compressor (Air Flow > 30m3/min)
|
CNP 003
|
1
|
|
Excavator with Mini Attachment
|
CNP 081
|
1
|
|
Breaker, excavator mounted
|
CNP 028
|
1
|
|
Generator
|
CNP 101
|
1
|
|
G2. Pipe Jacking
|
Concrete Mixer Truck
|
CNP 044
|
1
|
|
Crawler Crane with Concrete Skip
|
CNP 048
|
1
|
|
Dump Truck
|
CNP 067
|
2
|
|
Generator
|
CNP 101
|
1
|
|
Water Pump
|
CNP 281
|
2
|
|
3. Road Pavement and Finishes
|
|
G1. Road Pavement and Finishes
|
Ballast Temper
|
CNP 029
|
2
|
|
Compactor
|
CNP 050
|
1
|
|
Road Roller
|
CNP 185
|
1
|
|
Lorry
|
CNP 141
|
1
|
|
Asphalt Paver
|
CNP 004
|
1
|
|
Loader
|
CNP 081
|
1
|
|
Generator
|
CNP 101
|
1
|
|
4. Construction of Pumping Stations
|
|
P1. Foundation Work
|
Pilling, large diameter bored, reverse
circulation drill
|
CNP 166
|
2
|
|
Wheeled Excavator / Loader
|
CNP 081
|
1
|
|
Air Compressor (Air Flow > 30m3/min)
|
CNP 003
|
1
|
|
Dump Truck
|
CNP 067
|
1
|
|
Generator
|
CNP 101
|
1
|
|
Mobile Crane
|
CNP 048
|
1
|
|
P2. Superstructure
|
Air Compressor (Air Flow > 30m3/min)
|
CNP 003
|
1
|
|
Handheld Breaker (mass > 35kg)
|
CNP 026
|
1
|
|
Concrete Lorry Mixer
|
CNP 044
|
1
|
|
Poker Vibrator
|
CNP 170
|
1
|
|
Bar tender and cutter
|
CNP 021
|
1
|
|
Lorry
|
CNP 141
|
1
|
|
Mobile Crane
|
CNP 048
|
1
|
|
Saw, circular, wood
|
CNP 201
|
1
|
Detailed construction
schedule for the works is currently not available. The current study assumes that the construction activities will
occur during the normal working hours (ie 0700 to 1900 hours on any day other
than Sunday or public holiday). The
construction noise impacts will be assessed as follows:
·
locate representative NSRs that may be affected by the works;
·
determine the selected construction method and construction period.
·
determine plant items for corresponding construction activities based on
the agreed plant inventories with DSD;
·
determine the sound power levels of the plant items according to the
information stated in the TM-NCO or other recognised sources of reference,
where appropriate;
·
calculate the correction factors based on the distance between the NSRs
and the notional noise source positions of the work sites;
·
apply corrections including façade, distance, barrier attenuation,
acoustic reflection where applicable, in the calculations;
·
predict construction noise levels at the NSRs in the absence of any
mitigation measures;
·
conduct assessment of noise impacts at NSRs to quantify the level of
impact, in accordance with TM-CW, BS 5228; and
·
predict the cumulative noise impacts for any concurrent construction
works in the vicinity of the NSR.
An in-house program is
used for the analysis of the construction noise impact. The initial program runs are conducted
without any mitigation measures. Where
noise level exceedances are identified, further runs will have been made
assuming different combinations of mitigation measures to be incorporated to
control the impacts. Typical noise
mitigation measures often include selection of quiet plant and working methods,
erecting temporary barriers/enclosure, reducing number of plant items, and
controlling operating time, etc. If all best practicable noise mitigation
measures have been exhaustively reviewed but found to be ineffective, the
extent and duration of the noise exceedance, and the number of dwellings
affected are assessed in details.
There will be no construction work during
restricted hours. If any works during the restricted hours are required by the
Contractors, the Contractors shall apply for a CNP separately.
8.7.1 Unmitigated Scenario
Tin
Shui Wai Area (2A-1T)
The predicted unmitigated noise levels at the
representative NSRs for each construction activity in Tin Shui Wai Area are
shown in Table 8.7, taking into account the distance attenuation and façade
effect. Detailed calculation is shown in Appendix 8.3.
Table 8.7: Predicted noise level at the representative NSRs without mitigation
measures
|
NSR
|
Sewer Const[1]
|
Deep Bay Link
|
Ping Ha Road Widening
|
YLKTSS1
1B-2T
|
SWSTW Const
|
Alternative 4 Box Culvert Construction
|
157DS
|
Cumulative,
dBA
|
Criteria, dBA
|
|
NT01
|
78.5
|
53.0
|
|
54.1
|
66.3
|
74.1
|
|
80.1
|
75
|
|
NT02
|
73.2
|
53.0
|
|
56.7
|
66.3
|
62.4
|
|
74.5
|
75
|
|
NT03
|
73.9
|
54.0
|
|
57.9
|
67.3
|
63.4
|
|
75.2
|
75
|
|
NT04
|
66.5
|
49.0
|
|
53.1
|
62.3
|
66
|
58
|
70.5
|
75
|
|
NT05
|
86.1
|
48.0
|
|
51.3
|
|
68
|
62.7
|
86.2
|
75
|
|
NT06
|
91.3
|
|
|
|
|
63
|
58.2
|
91.3
|
75
|
|
NT07
|
78.9
|
|
47.5
|
|
|
|
|
78.9
|
75
|
|
NT08
|
90.6
|
|
88.0
|
|
|
|
59.4
|
92.5
|
75
|
|
NT09
|
80.5
|
|
46.6
|
|
|
|
|
80.5
|
65[4] (70)
|
|
NT10
|
90.6
|
|
46.2
|
|
|
|
|
90.6
|
75
|
|
NT11
|
90.2
|
|
|
|
|
|
|
90.2
|
75
|
|
NT12
|
0.0
|
|
|
|
|
|
|
87
|
75
|
|
NT13
|
80.8
|
|
|
|
|
|
|
80.8
|
75
|
|
NT14
|
88.6
|
|
|
|
|
|
|
88.6
|
75
|
|
NT15
|
90.6
|
|
|
|
|
|
|
90.6
|
75
|
|
NT16
|
100.1
|
|
|
|
|
|
|
100
|
75
|
|
NT17
|
98.2
|
|
|
|
|
|
|
98.2
|
75
|
|
NT18
|
96.6
|
|
|
|
|
|
|
96.6
|
75
|
|
NT20
|
98.2
|
|
31.1
|
|
|
|
|
98.2
|
75
|
|
NT21
|
98.2
|
|
|
|
|
|
|
98.2
|
75
|
|
NT22
|
96.6
|
|
|
|
|
|
|
96.6
|
75
|
|
NT23
|
83.8
|
|
|
|
|
|
|
83.8
|
75
|
|
NT24
|
96.6
|
|
|
|
|
|
|
96.6
|
75
|
|
NT25
|
90.6
|
|
|
|
|
|
|
90.6
|
75
|
|
NT28
|
85.3
|
|
|
|
|
|
|
85.3
|
65[4](70)
|
|
NT08a
|
89.2
|
|
68.0
|
|
|
|
|
89.2
|
75
|
|
NT22a
|
96.6
|
|
|
|
|
|
|
96.6
|
75
|
|
NT24a
|
98.2
|
|
|
|
|
|
|
98.2
|
75
|
|
NT29
|
86.1
|
|
|
43
|
|
|
|
86.1
|
65[4](70) / 75[6]
|
|
NT30
|
90.6
|
|
|
42.9
|
|
|
|
90.6
|
65[4](70) /75[6]
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3] Bolded values indicate the
exceedance of noise limit
[4]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
[5] For construction
activities of distance greater than 300m, the noise levels are not shown here
[6]
Axcillary Block consists of carparks, kindergarden and House for senior
centizen
As shown in Table 8.7, exceedance of cumulative noise
levels (2 – 25 dB(A) higher) are predicted at all sensitive receivers.
Different noise mitigation measures proposed in Section 8.8 should be adopted
to minimize the noise impacts.
Lau
Fau Shan Area (2A-3T)
The predicted unmitigated noise levels at the
representative NSRs for each construction activity in Lau Fau Shan Area are
shown in Table 8.8, taking into account the distance attenuation and façade
effect. Detailed calculation is given in Appendix 8.3.
Table 8.8: Predicted noise level at the representative NSRs without mitigation
measures
|
NSR
|
Sewer Construction[1]
|
SPS Construction
|
Ping Ha Road Widening
|
Cumulative
dB(A)
|
Criteria
dB(A)
|
|
NL02
|
89.2
|
74.1
|
41.3
|
89.3
|
75
|
|
NL03
|
92.1
|
71.3
|
40.6
|
92.2
|
75
|
|
NL04
|
89.9
|
77.3
|
41.1
|
90.1
|
75
|
|
NL05
|
87.5
|
70.3
|
42.4
|
87.6
|
75
|
|
NL06
|
90.6
|
66.7
|
44.5
|
90.6
|
75
|
|
NL07
|
90.6
|
|
46.3
|
90.6
|
75
|
|
NL08
|
92.1
|
|
48.4
|
92.1
|
75
|
|
NL09
|
88.6
|
|
48.4
|
88.6
|
75
|
|
NL10
|
92.1
|
|
52.0
|
92.1
|
75
|
|
NL11
|
83.8
|
|
59.7
|
83.9
|
75
|
|
NL12
|
83.8
|
|
60.4
|
83.9
|
75
|
|
NL13
|
96.6
|
|
69.9
|
96.6
|
75
|
|
NL14
|
77.2
|
|
45.7
|
77.2
|
75
|
|
NL15
|
77.3
|
|
42.8
|
77.3
|
75
|
|
NL16
|
77.3
|
|
|
77.3
|
75
|
|
NL18
|
77.7
|
|
|
77.8
|
75
|
|
NL19
|
77.3
|
|
|
77.4
|
75
|
|
NL20
|
76.6
|
|
|
76.7
|
75
|
|
NL21
|
77.3
|
|
|
77.5
|
75
|
|
NL22
|
94.1
|
73.1
|
|
94.1
|
75
|
|
NL23
|
90.6
|
82.7
|
|
91.2
|
75
|
|
NL24
|
92.1
|
80.1
|
|
92.4
|
75
|
|
NL25
|
84.2
|
84.6
|
|
87.4
|
75
|
|
NL26
|
86.1
|
85.8
|
|
89.0
|
75
|
|
NL27
|
83.3
|
81.1
|
|
85.4
|
75
|
|
NL28
|
85.3
|
84.6
|
|
88.0
|
75
|
|
NL15a
|
78.0
|
|
44.7
|
78.0
|
75
|
|
NL15b
|
77.3
|
|
|
77.3
|
65[3] (70)
|
|
NL29
|
93.1
|
74.4
|
|
93.1
|
75
|
|
NP01
|
98.2
|
|
54.9
|
98.2
|
75
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
As shown in Table 8.8, exceedance of cumulative noise
levels (2 – 24 dB(A) higher) are predicted at all NSR. Different noise
mitigation measures proposed in Section 8.8 should be adopted to minimize the
noise impacts.
Ngau
Tam Mei and San Tin Areas (2A-2T and 2B-1T)
The predicted unmitigated noise levels at the
representative NSRs for each construction activity in Ngau Tam Mei and San Tin
areas are shown in Table 8.9, taking into account the distance attenuation and
façade effect. Detailed calculation is given in Appendix 8.3.
Table 8.9: Predicted noise level at the representative NSRs without mitigation
measures
|
NSR
|
Sewer Construction[1]
|
SPS Construction
|
YLKTSS1
1A-1T S6
|
YLKTSS1
1A-1T P3
|
Cumulative
dB(A)
|
Criteria
dB(A)
|
|
NN02
|
102.6
|
|
|
|
102.6
|
75
|
|
NN03
|
77.5
|
|
|
|
77.5
|
65[3](70)
|
|
NN04
|
86.1
|
|
|
|
86.1
|
65[3](70)
|
|
NN05
|
92.1
|
|
|
|
92.1
|
75
|
|
NN06
|
90.6
|
|
|
|
90.6
|
75
|
|
NN07
|
87.3
|
74.4
|
|
|
87.5
|
75
|
|
NN08
|
82
|
78.1
|
|
|
83.5
|
65[3] (70)
|
|
NN09
|
96.6
|
71.8
|
|
|
96.6
|
75
|
|
NN10
|
87.0
|
77.6
|
|
|
87.5
|
65
|
|
NN11
|
88.1
|
78.9
|
|
|
88.5
|
75
|
|
NN12
|
82.0
|
70.0
|
|
|
82.3
|
75
|
|
NN13
|
81
|
64.6
|
|
|
81.1
|
75
|
|
NN14
|
75.5
|
67.1
|
|
|
76.1
|
75
|
|
NN15
|
88.6
|
87.1
|
|
|
90.9
|
75
|
|
NN17
|
95.9
|
|
|
|
95.9
|
75
|
|
NN18
|
81.8
|
|
|
|
81.8
|
75
|
|
NN19
|
91.3
|
|
|
|
91.3
|
75
|
|
NN20
|
81.0
|
|
|
|
81.0
|
75
|
|
NN21
|
93.1
|
|
|
|
93.1
|
75
|
|
NN22
|
95.2
|
|
|
|
95.2
|
75
|
|
NN23
|
96.6
|
|
|
|
96.6
|
65[3](70)
|
|
NN24
|
95.2
|
|
|
|
95.2
|
75
|
|
NN25
|
98.2
|
|
|
|
98.2
|
75
|
|
NN26
|
95.2
|
|
|
|
95.2
|
75
|
|
NN27
|
95.2
|
66.2
|
|
|
95.2
|
75
|
|
NN28
|
77.3
|
74.1
|
|
|
79.0
|
75
|
|
NN29
|
87.3
|
78.1
|
|
|
87.8
|
65[3](70)
|
|
NN30
|
87.0
|
73.0
|
|
|
87.2
|
75
|
|
NN31
|
88.6
|
66.0
|
|
|
88.6
|
75
|
|
NN31a
|
112.1
|
71.6
|
|
|
112.1[4]
|
75
|
|
NN33
|
108.6
|
72.3
|
|
|
108.6[4]
|
75
|
|
NN34
|
108.6
|
74.4
|
|
|
108.6[4]
|
75
|
|
NN35
|
108.6
|
74.1
|
|
|
108.6[4]
|
75
|
|
NN36
|
101.3
|
76.2
|
|
|
101.3[4]
|
75
|
|
NN37
|
90.2
|
70.7
|
|
|
90.2
|
75
|
|
NN38
|
101.3
|
75.6
|
|
|
101.3[4]
|
75
|
|
NN39
|
108.6
|
93.1
|
|
|
108.7[4]
|
75
|
|
NN40
|
108.6
|
88.7
|
|
|
108.7[4]
|
75
|
|
NN41
|
112.1
|
91.8
|
|
|
112.2[4]
|
75
|
|
NN42
|
94.1
|
64.7
|
|
|
94.1
|
65[3](70)
|
|
NN43
|
93.1
|
|
|
|
93.1
|
75
|
|
NN44
|
92.1
|
|
|
|
92.1
|
75
|
|
NN45
|
102.6
|
|
|
|
102.6
|
75
|
|
NN46
|
106.1
|
|
|
|
106.1
|
75
|
|
NN47
|
100.1
|
66.3
|
|
|
100.1
|
75
|
|
NN48
|
87.0
|
66.7
|
|
|
87.1
|
75
|
|
NN50
|
95.2
|
89.6
|
|
|
96.3
|
75
|
|
NN51
|
96.6
|
75.8
|
|
|
96.6
|
75
|
|
NN52
|
97.3
|
|
|
|
97.3
|
75
|
|
NN53
|
80.8
|
|
|
|
80.8
|
75
|
|
NN12a
|
82.3
|
66.3
|
|
|
82.4
|
75
|
|
NN12b
|
82.6
|
|
|
|
82.6
|
75
|
|
NN14a
|
80.3
|
73.1
|
|
|
81.1
|
75
|
|
NN16
|
78.0
|
75.1
|
|
|
79.8
|
75
|
|
NN19a
|
94.1
|
|
|
|
94.1
|
75
|
|
NN25a
|
87.0
|
|
|
|
87.0
|
75
|
|
NN26a
|
95.2
|
|
|
|
95.2
|
75
|
|
NN29a
|
91.3
|
76.2
|
|
|
91.4
|
75
|
|
NN32
|
106
|
71.6
|
|
|
106
|
75
|
|
NN42a
|
91.3
|
|
|
|
91.3
|
75
|
|
NN43a
|
90.6
|
|
|
|
90.6
|
75
|
|
D13
|
75.5
|
|
65.4
|
66.4
|
76.4
|
75
|
|
D42
|
69.3
|
|
75.0
|
61.5
|
76.2
|
75
|
|
NN01
|
88.1
|
|
|
|
88.1
|
75
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
[4]
The exceptional high noise level is due to the narrow width of the inner road
in the village. Hence, the NSR will be very close to the workfront. In the
mitigation measures proposed in next section, some of the equipment are
proposed to locate in the open space outside the village
As shown in Table 8.9, exceedance of cumulative noise
levels (1 – 37 dB(A) higher) are predicted at most NSR. Different noise
mitigation measures proposed in Section 8.8 should be adopted to minimize the
noise impact.
Shap
Pat Heung Area (2B-2T)
The predicted unmitigated noise levels at the
representative NSR for each construction activity in Shap Pat Heung Area are
shown in Table 8.10, taking into account the distance attenuation and façade
effect. Detailed calculation is given in Appendix 8.3.
Table 8.10: Predicted noise level at the representative NSRs without mitigation
measures
|
NSR
|
Sewer Construction[1]
|
SPS Construction
|
274DS
|
157DS
|
YL Highway
|
Cumulative
dB(A)
|
Criteria
dB(A)
|
|
NS01
|
91.8
|
77.9
|
88
|
47
|
42.5
|
93.4
|
75
|
|
NS02
|
84.2
|
79.5
|
88
|
45.5
|
41.9
|
89.9
|
75
|
|
NS03
|
86.1
|
77.8
|
88
|
46
|
41.5
|
90.4
|
75
|
|
NS04
|
85.3
|
85.8
|
88
|
45.1
|
41.5
|
91.3
|
75
|
|
NS05
|
79.8
|
|
52.4
|
61.1
|
42.8
|
80
|
75
|
|
NS06
|
87.2
|
84.3
|
88
|
45.2
|
41.7
|
91.5
|
75
|
|
NS07
|
88.9
|
75.7
|
88
|
46.8
|
43.1
|
91.6
|
75
|
|
NS08
|
87.5
|
|
55.3
|
54.5
|
49.9
|
88
|
75
|
|
NS09
|
83.8
|
|
53
|
64.5
|
59.1
|
84
|
75
|
|
NS10
|
82.6
|
|
55.7
|
63.4
|
58.4
|
82.8
|
75
|
|
NS11
|
104
|
|
72.4
|
|
49.5
|
104
|
75
|
|
NS12
|
89.9
|
|
58.7
|
|
54.4
|
89.9
|
75
|
|
NS13
|
93.1
|
69.0
|
54
|
|
50.7
|
93.1
|
75
|
|
NS14
|
89.2
|
72.7
|
51.6
|
|
48.8
|
89.3
|
75
|
|
NS15
|
82.8
|
73.2
|
49.4
|
|
45.7
|
83.3
|
75
|
|
NS16
|
98.2
|
73.4
|
49.2
|
|
46.4
|
98.2
|
75
|
|
NS17
|
96.6
|
83.7
|
|
|
43.7
|
96.8
|
75
|
|
NS18
|
88.1
|
84.7
|
|
|
43.9
|
89.7
|
75
|
|
NS19
|
88.1
|
69.3
|
|
|
40.5
|
88.1
|
75
|
|
NS20
|
90.6
|
76.1
|
|
|
|
90.7
|
75
|
|
NS21
|
80.5
|
76.9
|
|
|
|
82.1
|
75
|
|
NS22
|
86.1
|
78.0
|
|
|
|
86.7
|
75
|
|
NS23
|
89.2
|
77.7
|
|
|
|
89.5
|
75
|
|
NS24
|
94.1
|
69.7
|
48.6
|
|
|
94.1
|
75
|
|
NS25
|
96.6
|
|
56.2
|
|
|
96.6
|
75
|
|
NS26
|
104
|
|
51.7
|
|
|
104
|
75
|
|
NS27
|
96.6
|
|
66.8
|
|
|
96.6
|
75
|
|
NS28
|
94.1
|
|
88
|
|
|
95
|
75
|
|
NS30
|
90.6
|
|
68
|
|
|
90.6
|
75
|
|
NS31
|
101
|
73.9
|
|
|
|
101
|
75
|
|
NS32
|
90.6
|
|
60.9
|
|
54.6
|
90.6
|
75
|
|
NS34
|
103
|
67.6
|
55.9
|
|
51.8
|
103
|
75
|
|
NS35
|
100
|
82.1
|
|
|
41
|
100
|
75
|
|
NS36
|
94.1
|
94.7
|
|
|
41
|
97.4
|
75
|
|
NS37
|
85.3
|
82.2
|
|
|
40.6
|
87
|
75
|
|
NS38
|
81.5
|
76.6
|
|
|
40.2
|
82.7
|
75
|
|
NS39
|
89.2
|
78.6
|
|
|
|
89.6
|
75
|
|
NS40
|
87
|
87.9
|
|
|
|
90.5
|
75
|
|
NS41
|
88.1
|
80.2
|
|
|
|
88.7
|
75
|
|
NS42
|
100
|
|
58.4
|
|
|
100
|
75
|
|
NS43
|
83.8
|
|
69.9
|
|
|
84.1
|
75
|
|
NS44
|
83.2
|
|
88
|
|
|
89.2
|
75
|
|
NS45
|
96.6
|
74.5
|
|
|
42.2
|
96.6
|
75
|
|
NS46
|
100
|
77.5
|
|
|
41.5
|
100
|
75
|
|
NS47
|
96.6
|
|
82
|
|
64.4
|
96.7
|
75
|
|
NS48
|
92.1
|
|
54.2
|
|
50.6
|
92.2
|
75
|
|
NS50
|
82
|
80.1
|
|
|
43.8
|
84.2
|
75
|
|
NS51
|
100
|
71.0
|
|
|
43.2
|
100
|
75
|
|
NS52
|
92.1
|
84.8
|
|
|
42.7
|
92.9
|
75
|
|
NS53
|
92.1
|
83.8
|
|
|
42.5
|
92.7
|
75
|
|
NS54
|
98.2
|
70.9
|
|
|
|
98.2
|
75
|
|
NS55
|
94.1
|
|
|
|
|
94.1
|
75
|
|
NS56
|
100
|
|
|
|
|
100
|
75
|
|
NS57
|
100
|
|
|
|
|
100
|
75
|
|
NS58
|
91.3
|
|
|
|
|
91.3
|
75
|
|
NS59
|
93.1
|
|
|
|
|
93.1
|
75
|
|
NS60
|
96.6
|
|
|
|
|
96.6
|
75
|
|
NS61
|
94.1
|
|
|
|
|
94.1
|
75
|
|
NS64
|
103
|
|
69.9
|
|
61.9
|
103
|
75
|
|
NS65
|
90.6
|
|
61.2
|
|
55.6
|
90.6
|
75
|
|
NS66
|
106
|
|
53.7
|
|
50.4
|
106
|
75
|
|
NS67
|
87.5
|
68.9
|
48.1
|
|
45.3
|
87.6
|
75
|
|
NS68
|
103
|
69.9
|
|
|
44.7
|
103
|
75
|
|
NS69
|
89.2
|
86.5
|
|
|
41.8
|
91.1
|
75
|
|
NS70
|
90.6
|
87.1
|
|
|
41.1
|
92.2
|
75
|
|
NS71
|
87
|
81.2
|
|
|
41.2
|
88
|
75
|
|
NS72
|
104
|
69.3
|
|
|
|
104
|
75
|
|
NS73
|
90.6
|
68.1
|
|
|
|
90.6
|
75
|
|
NS19a
|
98.2
|
|
|
|
|
98.2
|
75
|
|
NS19b
|
98.2
|
68.7
|
|
|
|
98.2
|
75
|
|
NS19c
|
89.2
|
68.0
|
|
|
|
89.2
|
75
|
|
NS37a
|
95.2
|
77.2
|
|
|
|
95.3
|
75
|
|
NS37b
|
106
|
74.1
|
|
|
|
112
|
75
|
|
NS39a
|
96.6
|
71.7
|
|
|
|
96.6
|
75
|
|
NS39b
|
103
|
71.9
|
|
|
|
103
|
75
|
|
NS42a
|
96.6
|
|
|
|
|
96.6
|
75
|
|
NS48a
|
90.6
|
|
|
|
54.4
|
90.6
|
75
|
|
NS49a
|
100
|
|
50.8
|
|
52
|
100
|
75
|
|
NS52a
|
100
|
90.7
|
|
|
42.7
|
101
|
75
|
|
NS70a
|
104
|
84.7
|
|
|
40.9
|
104
|
75
|
|
NS74
|
90.6
|
|
|
|
46.8
|
90.6
|
75
|
|
NS49b
|
86.6
|
70.0
|
|
|
|
86.7
|
65[3](70)
|
|
NS76
|
103
|
74.1
|
|
|
|
103
|
75
|
|
NS76b
|
94.1
|
74.1
|
|
|
|
94.1
|
75
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
As shown in Table 8.10, exceedance of cumulative noise
levels (5 – 31 dB(A) higher) are predicted at most NSRs. Different noise
mitigation measures proposed in Section 8.8 should be adopted to minimize the
noise impacts.
Noise emission from construction activities can be
minimized through good site practice, selecting quiet plant, adopting quieter
working methods, erection of noise barriers to screen the noise source, where
appropriate, and imposing restrictions on the use of noisy equipment.
8.8.1 Good site Practice
In view of the different construction activities and items
of construction equipment used, adverse construction noise impacts on the
surrounding environment are likely unless mitigation measures are implemented.
Good site practice and proper on-site measurement are required by Contractors
at all times in order to minimize noise emissions from the works. The following
measures are recommended.
· Only well-maintained plant shall be
operated on site and plant shall be serviced regularly during the construction
work.
· Machines and plant that may be in
intermittent use (such as breakers) shall be shut down between work periods or
should be throttled down to a minimum.
· Silencers or mufflers on construction
equipment shall be utilised and be properly maintained during the construction
works.
· Mobile plant shall be sited as far away
from NSRs as possible.
· Material stockpiles and other structures
shall be effectively utilised, where practicable, to screen noise from on-site
construction activities.
· Plant known to emit noise
strongly in one direction, should, where possible, be orientated to direct
noise away from nearby NSRs.
Although it is difficult to quantify the level of noise
reduction achieved from implementation of these practices, the environmental
performance of the works would be improved with these control measures.
8.8.2 Quieter Plant
One feasible method to reduce the noise level is the
adoption of quieter plant. Quieter plant is defined as the PME with actual SWL
being less than the value specified in the TM-CW. In fact, the contractor shall
obtain particular models of plant that are quieter than the standard type as
stipulated in the TM-CW. Example of SWLs for specific silenced PME can be found
in BS 5228 Part I:1997 “Noise Control on Construction Open Sites,”.
The silenced PME that known to be used are given in Table
8.11. With the use of quieter plant, the noise level could be reduced by 1 - 15
dB(A).
Table 8.11: Quieter construction plant
inventory
|
PME
|
CNP Code
|
SWL dB(A)
|
BS 5228
|
SWL dB(A)
|
Reduction dB(A)
|
|
1. Sewers and Rising Main using Open Trench Method
|
|
Pilling, oscillator
|
CNP 165
|
115
|
EIA[1]
|
104
|
11
|
|
Excavator with Mini Attachment
|
CNP 081
|
112
|
C8-33
|
102
|
10
|
|
Breaker, excavator mounted
|
CNP 028
|
122
|
C8-13
|
110
|
12
|
|
Dump Truck
|
CNP 067
|
117
|
C9-19
|
102
|
15
|
|
Roller / Vibrating Roller
|
CNP 186
|
108
|
C3-115
|
102
|
6
|
|
Concrete Mixer Truck
|
CNP 044
|
109
|
C6-35
|
100
|
9
|
|
Concrete Poker Vibrator
|
CNP 170
|
113
|
C6-32
|
100
|
13
|
|
Crawler Crane with Concrete Skip
|
CNP 048
|
112
|
C7-106
|
99
|
13
|
|
Flat Bed Lorry
|
CNP 141
|
112
|
C9-19
|
102
|
10
|
|
Generator
|
CNP 101
|
108
|
CNP 103
|
95
|
13
|
|
2. Sewers and Rising Main Using Pipe Jacking Method
|
|
Air Compressor (Air Flow > 30m3/min)
|
CNP 003
|
104
|
C7-44
|
103
|
1
|
|
Excavator with Mini Attachment
|
CNP 081
|
112
|
C3-35
|
106
|
6
|
|
Breaker, excavator mounted
|
CNP 028
|
122
|
C8-13
|
110
|
12
|
|
Generator
|
CNP 101
|
108
|
CNP 103
|
95
|
13
|
|
Concrete Mixer Truck
|
CNP 044
|
109
|
C6-35
|
100
|
9
|
|
Crawler Crane with Concrete Skip
|
CNP 048
|
112
|
C7-106
|
99
|
13
|
|
Dump Truck
|
CNP 067
|
117
|
C9-19
|
102
|
15
|
|
Water Pump
|
CNP 281
|
88
|
N/A
|
N/A
|
N/A
|
|
3. Road Pavement and Finish
|
|
Ballast Temper
|
CNP 029
|
105
|
N/A
|
N/A
|
N/A
|
|
Compactor
|
CNP 050
|
105
|
N/A
|
N/A
|
N/A
|
|
Road Roller + Lorry
|
CNP 185 / CNP 141
|
108 / 112
|
C8-25
|
96
|
17
|
|
Asphalt Paver
|
CNP 004
|
109
|
C8-24
|
101
|
8
|
|
Loader
|
CNP 081
|
112
|
C8-15
|
103
|
9
|
|
Generator
|
CNP 101
|
108
|
CNP 103
|
95
|
13
|
|
4. Construction of the Sewage Pumping Station
|
|
Pilling, large diameter bored, reverse circulation drill
|
CNP 166
|
100
|
N/A
|
N/A
|
N/A
|
|
Wheeled Excavator / Loader
|
CNP 081
|
112
|
C3-80
|
106
|
6
|
|
Air Compressor (Air Flow > 30m3/min)
|
CNP 003
|
104
|
C7-44
|
103
|
1
|
|
Dump Truck
|
CNP 067
|
117
|
C9-27
|
105
|
12
|
|
Generator
|
CNP 101
|
108
|
CNP 103
|
95
|
13
|
|
Mobile Crane
|
CNP 048
|
112
|
C7-110
|
106
|
6
|
|
Handheld Breaker (mass > 35kg)
|
CNP 026
|
114
|
C2-10
|
110
|
4
|
|
Concrete Lorry Mixer
|
CNP 044
|
109
|
C6-35
|
100
|
9
|
|
Poker Vibrator
|
CNP 170
|
113
|
C6-32
|
100
|
13
|
|
Bar tender and cutter
|
CNP 021
|
90
|
N/A
|
N/A
|
N/A
|
|
Lorry
|
CNP 141
|
112
|
C9-27
|
105
|
7
|
|
Mobile Crane
|
CNP 048
|
112
|
C7-109
|
103
|
6
|
|
Saw, circular, wood
|
CNP 201
|
108
|
C7-75
|
105
|
3
|
Note
[1] : Adopted from EIA
report of Yuen Long and Kam Tin Sewerage and Sewage Disposal Stage 1
It should be noted that various type of silenced equipment
are available in Hong Kong. However, when processing a CNP application, the EPD
will apply the noise levels contained in the TM-CW, unless the noise emission
of a particular equipment can be validated.
8.8.3 Restrict the type of PME used Concurrently
During the
construction of gravity sewer and rising mains, PME such as excavator mounted
breakers and excavators will not be operated concurrently as the works are
usually carried out using same equipment in sequence. In addition, the use of
handheld breaker instead of excavator mounted breakers is recommended for the
road opening works. The refined plant groups are summarized in Table 8.12.
Table
8.12: Refinement of plant group
|
Activities
|
Plant
|
TM ref
|
Quiet Plant
ref
|
Unit
|
|
1. Sewers and Rising Main using Open Trench Method
|
|
G1. Site
Preparation
|
Pilling, oscillator
|
CNP 165
|
By contractor[1]
|
1
|
|
G2. Road
opening
|
Handheld Breaker (mass > 35kg)
|
CNP 048
|
C2-10
|
1
|
|
G3. Trench
excavation and earth work
|
Excavator for trenching
|
CNP 081
|
C8-33
|
1
|
|
G4. Sewer
Laying
|
Loader
|
CNP081
|
C8-15
|
1
|
|
Medium Size Truck
|
CNP 141
|
C9-19
|
1
|
|
G5. Earthworks
|
Roller / Vibrating Roller
|
CNP 186
|
C3-115
|
1
|
|
G6. Finishes
|
Concrete Lorry Mixer
|
CNP 044
|
C6-35
|
1
|
|
Concrete Poker Vibrator
|
CNP 170
|
C6-32
|
1
|
|
Crawler Crane with Concrete Skip
|
CNP 048
|
C7-106
|
1
|
|
Medium Size Truck
|
CNP 141
|
C9-19
|
1
|
|
2. Sewers and Rising Main using Pipe Jacking Method
crossing streams
|
|
G1. Site
Preparation
|
Breaker, excavator mounted
|
CNP 026
|
C8-13
|
1
|
|
G2. Earthwork
excavation
|
Excavator with Multi Attachment
|
CNP 081
|
C3-35
|
1
|
|
G3. Pipe Jacking
|
Concrete Mixer Truck
|
CNP 044
|
C6-35
|
1
|
|
Crawler Cane with Concrete Skip
|
CNP 048
|
C7 -106
|
1
|
|
Lorry
|
CNP 067
|
C9-19
|
1
|
|
Generator
|
CNP 101
|
CNP 103
|
1
|
|
Water Pump
|
CNP 281
|
N/A
|
1
|
|
3. Road Pavement and Finishes
|
|
R1. Ballast
Laying
|
Ballast Tamper
|
CNP 029
|
N/A
|
1
|
|
R2. Compacting
|
Compactor
|
CNP 050
|
N/A
|
1
|
|
R3. Road Paving
|
Road Roller + Lorry
|
CNP 185/ CNP141
|
C8-25
|
1
|
|
Asphalt Paver
|
CNP 004
|
C8-24
|
1
|
|
Loader
|
CNP 081
|
C8-15
|
1
|
|
Generator
|
CNP 101
|
C7-62
|
1
|
Note [1] : Adopted from EIA report of Yuen Long
and Kam Tin Sewerage and Sewage Disposal Stage 1
8.8.4 Use of Temporary or Movable Noise Barriers
In general,
purpose-built noise barriers or movable noise barrier constructed of
appropriate material (with a superficial density of at least 20kg/m2)
and located close to the PME could give a further noise reduction of 5dB(A),
according to TM-CW. Certain types of PME, such as generator, can be completely
screened giving a total reduction of 10dB(A) or more. However, as the present
works area for the sewer laying works and road Pavement and Finish Works will
be very small (~ 3 to 3.5m in width) and the excavated trench is expected to
occupy most of the area. The use of the moveable noise barrier is therefore not
feasible for these works.
During the road
opening work, acoustic shed of dimension 2m ´ 2m ´ 2.7m can be used to shield the noise
emitted from handheld breaker. A maximum of 10 dB(A) can be attained.
For the
construction of the sewerage pumping station, the works area will allow the
installation of moveable barrier and construction of hoarding. As most of the
NSRs are 2 to 3 storeys high and the pumping station construction site is of
area ~15m ´ 15m, hoarding of 3m high shall be erected around the pumping station
construction site. Table 8.13 summarizes the SWL of the PME with the barrier /
or enclosure included.
Table
8.13: SWL of the PME with
barrier/ enclosure included.
|
|
CNP Code
|
SWL
|
Barrier type
|
Barrier
effect
|
SWL
|
|
Construction of Sewer
|
|
Road Opening
|
|
Handheld Breaker
|
C2-10
|
110
|
Acoustic Shed
|
10
|
100
|
|
Construction of Pumping Station
|
|
Foundation Work
|
|
Pilling, large diameter bored, reverse circulation drill
|
CNP 166
|
100
|
Movable Barrier
|
5
|
95
|
|
Wheeled Excavator / Loader
|
C3-80
|
106
|
Movable Barrier
|
5
|
101
|
|
Air Compressor (Air Flow > 30m3/min)
|
C7-44
|
103
|
Movable Barrier
|
10
|
93
|
|
Dump Truck
|
C9-27
|
105
|
Movable Barrier
|
5
|
100
|
|
Generator
|
CNP103
|
95
|
Movable Barrier
|
10
|
85
|
|
Mobile Crane
|
C7-110
|
106
|
Movable Barrier
|
5
|
101
|
|
Superstructure Work
|
|
Air Compressor (Air Flow > 30m3/min)
|
C7-44
|
103
|
Movable Barrier
|
10
|
93
|
|
Handheld Breaker (mass > 35kg)
|
C2-10
|
110
|
Acoustic Shed
|
10
|
100
|
|
Concrete Lorry Mixer
|
C6-35
|
100
|
Movable Barrier
|
5
|
95
|
|
Poker Vibrator
|
C6-32
|
100
|
Movable Barrier
|
5
|
95
|
|
Bar tender and cutter
|
CNP 021
|
90
|
Movable Barrier
|
10
|
80
|
|
Lorry
|
C9-27
|
105
|
Movable Barrier
|
5
|
100
|
|
Mobile Crane
|
C7-110
|
106
|
Movable Barrier
|
5
|
101
|
|
Saw, circular, wood
|
C7-75
|
105
|
Movable Barrier
|
10
|
95
|
The potential
construction noise impact after mitigation measures is summarized in Table 8.14
– Table 8.17. The SWL of the construction plant inventory with mitigation
measures are given in Appendix 8.2.
Tin
Shui Wai Area (2A-1T)
The predicted mitigated noise levels at the representative
NSRs for each construction activity in Tin Shui Wai Area are shown in Table
8.14, taking into account the distance attenuation and façade effect. Detailed
calculation is given in Appendix 8.3.
Table 8.14: Predicted noise level at the representative NSRs with mitigation
measures
|
NSR
|
Sewer Const[1]
|
Deep Bay Link
|
Ping Ha Road Widening
|
YLKTSS1
1B-2T
|
SWSTW Const
|
Alternative 4 Box Culvert Construction
|
157DS
|
Cumulative
dB(A)
|
Criteria
dB(A)
|
|
NT01
|
61.8
|
53
|
|
54.1
|
66.3
|
74.1
|
|
75
|
75
|
|
NT02
|
56.5
|
53
|
|
56.7
|
66.3
|
62.4
|
|
68.6
|
75
|
|
NT03
|
57.1
|
54
|
|
57.9
|
67.3
|
63.4
|
|
69.5
|
75
|
|
NT04
|
49.7
|
49
|
|
53.1
|
62.3
|
66
|
58
|
68.3
|
75
|
|
NT05
|
69.4
|
48
|
|
51.3
|
|
68
|
62.7
|
72.3
|
75
|
|
NT06
|
74.6
|
|
|
|
|
63
|
58.2
|
75
|
75
|
|
NT07
|
62.2
|
|
47.5
|
|
|
|
|
62.4
|
75
|
|
NT08
|
73.8
|
|
88
|
|
|
|
59.4
|
88.1
|
75
|
|
NT09
|
67.4
|
|
46.6
|
|
|
|
|
67.5
|
65[4] (70)
|
|
NT10
|
73.8
|
|
46
|
|
|
|
|
73.8
|
75
|
|
NT11
|
73.5
|
|
|
|
|
|
|
73.5
|
75
|
|
NT12
|
70.3
|
|
|
|
|
|
|
70.3
|
75
|
|
NT13
|
64
|
|
|
|
|
|
|
64.1
|
75
|
|
NT14
|
71.9
|
|
|
|
|
|
|
71.9
|
75
|
|
NT15
|
73.8
|
|
|
|
|
|
|
73.8
|
75
|
|
NT16
|
83.4
|
|
|
|
|
|
|
83.4
|
75
|
|
NT17
|
81.4
|
|
|
|
|
|
|
81.4
|
75
|
|
NT18
|
79.8
|
|
|
|
|
|
|
79.8
|
75
|
|
NT20
|
81.4
|
|
|
|
|
|
|
81.4
|
75
|
|
NT21
|
81.4
|
|
|
|
|
|
|
81.4
|
75
|
|
NT22
|
79.8
|
|
|
|
|
|
|
79.8
|
75
|
|
NT23
|
67.1
|
|
|
|
|
|
|
67.1
|
75
|
|
NT24
|
79.8
|
|
|
|
|
|
|
79.8
|
75
|
|
NT25
|
73.8
|
|
|
|
|
|
|
73.8
|
75
|
|
NT28
|
68.6
|
|
|
|
|
|
|
68.6
|
65[4] (70)
|
|
NT08a
|
72.5
|
|
68
|
|
|
|
56.1
|
73.8
|
75
|
|
NT22a
|
79.8
|
|
|
|
|
|
|
79.8
|
75
|
|
NT24a
|
81.4
|
|
|
|
|
|
|
81.4
|
75
|
|
NT29
|
69.4
|
|
|
43
|
|
|
|
69.4
|
65[4] (70) /75[5]
|
|
NT30
|
73.8
|
|
|
42.9
|
|
|
|
73.8
|
65[4] (70) /75[5]
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3] Bolded values indicate the
exceedance of noise limit
[4]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
[5]
Axcillary Block consists of carparks, kindergarden and House for senior
centizen
As shown in Table 8.14, residual exceedance in noise
levels (1 – 13 dB(A) higher) are still predicted at most sensitive receivers.
As a general mitigation strategy for the affected schools, construction should
be given to scheduling the construction work at the school workfront outside the
examination period in order to reduce the noise impact. This applies to NT09
(Tung Hoi Lee Primary School), NT28 (Lee Shau Kee Primary School) and NT29
(Kindergarden in Tin Wah Estate Auxillary Facility Block). However, for NT30
(Kindergarden in Tin Yuet Estate Auxillary Facility Block), the mitigated noise
level still
exceeds the riteria for both the examination period and normal school days.
Hence, the construction work shall be scheduled outside the normal school days
and examination period. The construction of sewer and Ping Ha Road widening
should also not be taken place concurrently as they dominate the noise impact
at NT08 (scattered village house). Hence, it is suggested to schedule the sewer
construction in the workfront of NT08 before or after the Ping Ha Road
Widening.
Lau
Fau Shan Area (2A-3T)
The predicted mitigated noise levels at the representative
NSRs for each construction activity in Lau Fau Shan Area are shown in Table 8.15,
taking into account the distance attenuation and façade effect. Detailed
calculation is given in Appendix 8.3.
Table 8.15: Predicted noise level at the representative NSRs with mitigation
measures
|
NSR
|
Sewer Construction[1]
|
SPS Construction
|
Ping Ha Road Widening
|
Cumulative
dB(A)
|
Criteria
dB(A)
|
|
NL02
|
72.5
|
60.8
|
|
72.8
|
75
|
|
NL03
|
75.4
|
58.1
|
|
75.5
|
75
|
|
NL04
|
73.1
|
64.1
|
|
73.6
|
75
|
|
NL05
|
70.8
|
57.1
|
|
71.0
|
75
|
|
NL06
|
73.8
|
53.4
|
|
73.9
|
75
|
|
NL07
|
73.8
|
|
|
73.9
|
75
|
|
NL08
|
75.4
|
|
|
75.4
|
75
|
|
NL09
|
71.9
|
|
|
71.9
|
75
|
|
NL10
|
75.4
|
|
52.0
|
75.4
|
75
|
|
NL11
|
67.1
|
|
59.7
|
67.9
|
75
|
|
NL12
|
67.1
|
|
60.4
|
68.0
|
75
|
|
NL13
|
79.8
|
|
69.9
|
80.3
|
75
|
|
NL14
|
60.4
|
|
|
60.6
|
75
|
|
NL15
|
60.6
|
|
|
60.7
|
75
|
|
NL16
|
60.6
|
|
|
60.7
|
75
|
|
NL18
|
61.0
|
|
|
61.1
|
75
|
|
NL19
|
60.6
|
|
|
60.7
|
75
|
|
NL20
|
59.8
|
|
|
60.1
|
75
|
|
NL21
|
60.6
|
|
|
60.9
|
75
|
|
NL22
|
77.3
|
59.9
|
|
77.4
|
75
|
|
NL23
|
73.8
|
69.4
|
|
75.2
|
75
|
|
NL24
|
75.4
|
66.8
|
|
76.0
|
75
|
|
NL25
|
67.5
|
71.4
|
|
72.8
|
75
|
|
NL26
|
69.4
|
72.5
|
|
74.2
|
75
|
|
NL27
|
66.6
|
67.8
|
|
70.3
|
75
|
|
NL28
|
68.6
|
71.4
|
|
73.2
|
75
|
|
NL15a
|
61.3
|
|
|
61.4
|
75
|
|
NL15b
|
60.6
|
|
|
60.7
|
65[3] (70)
|
|
NL29
|
76.3
|
61.1
|
|
76.5
|
75
|
|
NP01
|
81.4
|
|
54.9
|
81.4
|
75
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
As shown in Table 8.15, residual exceedance in noise
levels (1 – 6 dB(A) higher) are still predicted at most sensitive receivers.
The construction of sewer and sewage pumping station should also not be taken
place concurrently as they dominate the noise impact at NL03 and NL24.
Ngau
Tam Mei and San Tin Areas (2A-2T and 2B-1T)
The predicted mitigated noise levels at the representative
NSRs for each construction activity in Ngau Tam Mei and San Tin areas are shown
in Table 8.16a, taking into account the distance attenuation and façade effect.
Detailed calculation is given in Appendix 8.3.
Table 8.16a: Predicted noise level at the representative NSRs with mitigation
measures
|
NSR
|
Sewer Construction
|
SPS Construction
|
YLKTSS1
1A-1T S6
|
YLKTSS1
1A-1T P3
|
Cumulative
dB(A)
|
Criteria
dB(A)
|
|
NN02
|
85.9
|
|
|
|
85.9
|
75
|
|
NN03
|
60.8
|
|
|
|
60.8
|
65[4] (70)
|
|
NN04
|
69.4
|
|
|
|
69.4
|
65[4] (70)
|
|
NN05
|
75.4
|
|
|
|
75.4
|
75
|
|
NN06
|
73.8
|
|
|
|
73.8
|
75
|
|
NN07
|
70.6
|
61.1
|
|
|
71.0
|
75
|
|
NN08
|
65.3
|
64.8
|
|
|
68.1
|
65[4](70)/75[6]
|
|
NN09
|
79.8
|
58.5
|
|
|
79.9
|
75
|
|
NN10
|
70.3
|
64.3
|
|
|
71.3
|
65
|
|
NN11
|
71.3
|
65.6
|
|
|
72.4
|
75
|
|
NN12
|
65.3
|
56.8
|
|
|
65.9
|
75
|
|
NN13
|
64.3
|
51.4
|
|
|
74.5
|
75
|
|
NN14
|
58.8
|
53.9
|
|
|
60
|
75
|
|
NN15
|
71.9
|
73.9
|
|
|
76.0
|
75
|
|
NN17
|
79.2
|
|
|
|
79.2
|
75
|
|
NN18
|
65.0
|
|
|
|
65.1
|
75
|
|
NN19
|
74.6
|
|
|
|
74.6
|
75
|
|
NN20
|
64.3
|
|
|
|
64.4
|
75
|
|
NN21
|
76.3
|
|
|
|
76.3
|
75
|
|
NN22
|
78.5
|
|
|
|
78.5
|
75
|
|
NN23
|
79.8
|
|
|
|
79.8
|
65[4] (70)
|
|
NN24
|
78.5
|
|
|
|
78.5
|
75
|
|
NN25
|
81.4
|
|
|
|
81.4
|
75
|
|
NN26
|
78.5
|
|
|
|
78.5
|
75
|
|
NN27
|
78.5
|
52.9
|
|
|
78.5
|
65
|
|
NN28
|
62.6
|
60.8
|
|
|
64.8
|
75
|
|
NN29
|
70.6
|
64.9
|
|
|
71.6
|
65[4] (70)
|
|
NN30
|
70.3
|
59.7
|
|
|
70.7
|
75
|
|
NN31
|
71.9
|
52.8
|
|
|
71.9
|
75
|
|
NN31a
|
95.4
|
58.3
|
|
|
95.4
|
75
|
|
NN33
|
91.9
|
59.1
|
|
|
91.9
|
75
|
|
NN34
|
91.9
|
61.1
|
|
|
91.9
|
75
|
|
NN35
|
91.9
|
60.8
|
|
|
91.9
|
75
|
|
NN36
|
85.5
|
63.0
|
|
|
84.6
|
75
|
|
NN37
|
73.5
|
57.4
|
|
|
73.6
|
75
|
|
NN38
|
84.5
|
62.3
|
|
|
84.6
|
75
|
|
NN39
|
91.9
|
79.9
|
|
|
92.2
|
75
|
|
NN40
|
91.9
|
75.4
|
|
|
92.0
|
75
|
|
NN41
|
95.4
|
78.5
|
|
|
95.5 (85.5)[5]
|
75
|
|
NN42
|
77.3
|
51.5
|
|
|
77.4
|
65[4] (70)
|
|
NN43
|
76.3
|
|
|
|
76.3
|
75
|
|
NN44
|
75.4
|
|
|
|
75.4
|
75
|
|
NN45
|
85.9
|
|
|
|
85.9
|
75
|
|
NN46
|
89.4
|
|
|
|
89.4
|
75
|
|
NN47
|
83.4
|
53.0
|
|
|
83.4
|
75
|
|
NN48
|
70.3
|
53.4
|
|
|
70.4
|
75
|
|
NN50
|
78.5
|
76.4
|
|
|
80.6
|
75
|
|
NN51
|
79.8
|
62.6
|
|
|
79.9
|
75
|
|
NN52
|
80.6
|
|
|
|
80.6
|
75
|
|
NN53
|
64.0
|
|
|
|
64.1
|
75
|
|
NN12a
|
65.6
|
53.0
|
|
|
65.8
|
75
|
|
NN12b
|
65.9
|
|
|
|
66.0
|
75
|
|
NN14a
|
63.6
|
59.9
|
|
|
65.1
|
75
|
|
NN16
|
61.3
|
61.8
|
|
|
64.6
|
75
|
|
NN19a
|
77.3
|
|
|
|
77.4
|
75
|
|
NN25a
|
70.3
|
|
|
|
70.3
|
75
|
|
NN26a
|
78.5
|
|
|
|
78.5
|
75
|
|
NN29a
|
74.6
|
63.0
|
|
|
74.9
|
75
|
|
NN32
|
89.4
|
58.3
|
|
|
89.4
|
75
|
|
NN42a
|
74.6
|
|
|
|
74.6
|
75
|
|
NN43a
|
73.8
|
|
|
|
73.8
|
75
|
|
D13
|
58.8
|
|
65.4
|
66.4
|
69.4
|
75
|
|
D42
|
52.6
|
|
75.0
|
61.5
|
75.2
|
75
|
|
NN01
|
71.3
|
|
54.4
|
55.4
|
71.5
|
75
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3]
From Table 8.16a
[4]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
[5]
Presence of high boundary wall outside the Tse Tong, which will provide an
attenuation of 10dB
As shown in Table 8.16a, residual exceedance in noise
levels (1 – 20 dB(A) higher) are still predicted at most sensitive receivers.
The construction of sewer and sewage pumping station should also not be taken
place concurrently as they dominate the noise impact at NN15 and NN37. In order
to reduce the noise impact on schools at NN04, NN23, NN29(planned)
and NN42, the mitigation measures proposed in Table 8.16b are suggested.
Table 8.16b: Mitigation measures for schools in San
Tin
|
NSR
|
Noise Level
|
Noise Criteria
|
Mitigation Measures
|
|
NN04 (School)
|
69.4
|
65 (70)[1]
|
No Construction work in
the workfront during Examination Periods
|
|
NN08 (School)
|
68.1
|
65 (70)
|
No simultaneous sewerage and sewage pumping
station construction works in the work front during examination period
|
|
NN23 (School)
|
79.8
|
65 (70)
|
No Construction work in the workfront at
Normal School days and Examination Periods
|
|
NN29 (planned School)
|
70.6
|
65 (70)
|
No mitigation measures required
if the school is not built
No Sewerage work in the work front at
Normal School days
No Construction work in the work front during
Examination Periods
|
|
NN42 (School)
|
77.3
|
65 (70)
|
No Construction work in the workfront during
Normal School days and Examination Periods
|
[1] For school, the noise limit is 70 dB(A).
However, during examination, the noise limit is 65 dB(A).
NN41 is the Man Tung Fung Tse Tong, which is surrounded by
high boundary walls. It is anticipated that the boundary walls
will greatly attenuate the noise due to the sewer construction. Nevertheless,
it is suggested that there should be no construction works during any
ceremony activities inside the Man Tung Fung Tse Tong.
The predicted noise levels at some NSRs in San Lung Tsuen
have reached 95 dB(A). Given that the inner roads of San Lung Tsuen are
extremely narrow (~4m), PME such as lorry, generator, crawler crane, truck, etc
will be relocated in the open space just outside the village and away from the
workfront. The narrow site constraints also mean material transportation and
sewage laying work will need to be performed manually. As the sewer
construction is on a small and narrow local road, smaller power mechanical
equipment (e.g. road breaker and concrete vibratory poker) can be used.
Besides, the percentage on time for some PME (e.g. road roller) can be further
reduced. All these will contribute to the reduction of the noise impact. The proposed PME locations
at the
open area of San Lung Tsuen (S6) are shown in Appendix 8.5. As agreed with DSD, either one of the sites
can be selected as the temporary works areas.
Hence, the present noise calculation was based on temporary work area
A. Application for the inclusion in the
works site boundary will be carried out at the detailed design stage by DSD. The
revised cumulative noise levels at the NSRs in San Lung Tsuen are shown in
Table 8.16c. Detailed noise calculations are given in Appendix 8.4.
Table 8.16c: Revised predicted noise level at
the representative NSRs in San Lung Tsuen taking site constraint into consideration
|
NSR
|
Sewer Construction[1]
|
SPS Construction
|
YLKTSS1
1B-2T
|
YLKTSS1
1A-1T
|
Previous noise level [3], dB(A)
|
Cumulative
dB(A)
|
Criteria
dB(A)
|
|
NN31a
|
90
|
58.3
|
|
|
95.4
|
90
|
75
|
|
NN32
|
84
|
58.3
|
|
|
89.4
|
84
|
75
|
|
NN33
|
86.5
|
59.1
|
|
|
91.9
|
86.5
|
75
|
|
NN34
|
86.5
|
61.1
|
|
|
91.9
|
86.5
|
75
|
|
NN35
|
86.5
|
60.8
|
|
|
91.9
|
86.5
|
75
|
|
NN36
|
79.1
|
63.0
|
|
|
85.5
|
79.3
|
75
|
|
NN38
|
79.1
|
65.9
|
|
|
84.5
|
79.3
|
75
|
|
NN39
|
86.5
|
73.9
|
|
|
91.9
|
86.7
|
75
|
|
NN40
|
85.5
|
75.4
|
|
|
87.7
|
86.8
|
75
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
With the relocation of the PME, the noise levels at the
NSRs in San Tung Tsuen have been reduced by ~ 5 dB(A). Higher noise level is
still predicted
at NN31a. Site inspection indicated that NN31 is one storey house. Hence, a
moveable barrier of 3m high can be erected in front of the house. This will
further reduce the noise level to 80 dB(A).
NN34 is another Tse Tong in San Lung Tsuen. However, the Tse
Tong is not surrounded by high boundary walls. Hence, it is suggested that
there should
be no construction works during any ceremony activities inside the Tse
Tong.
Shap
Pat Heung Area (2B-2T)
The predicted unmitigated noise levels at the
representative NSRs for each construction activity in Shap Pat Heung Area are
shown in Table 8.17, taking into account the distance attenuation and façade
effect. Detailed calculation is given in Appendix 8.3.
Table 8.17: Predicted noise level at the representative NSRs with mitigation
measures
|
NSR
|
Sewer Construction[1]
|
SPS Construction
|
274DS
|
157DS
|
YL Highway
|
Cumulative
|
Cumulative Programme
(Re-schedule to after 274DS)
dB(A)
|
Criteria
dB(A)
|
|
NS01
|
75.1
|
64.6
|
88
|
47
|
42.5
|
88.2
|
75.5
|
75
|
|
NS02
|
67.5
|
66.2
|
88
|
45.5
|
41.9
|
88
|
69.9
|
75
|
|
NS03
|
69.4
|
64.6
|
88
|
46
|
41.5
|
88.1
|
70.7
|
75
|
|
NS04
|
68.6
|
72.5
|
88
|
45.1
|
41.5
|
88.1
|
74
|
75
|
|
NS05
|
63.1
|
|
52.4
|
61.1
|
42.8
|
65.7
|
65.4
|
75
|
|
NS06
|
70.5
|
71
|
88
|
45.2
|
41.7
|
88.1
|
73.8
|
75
|
|
NS07
|
72.2
|
62.4
|
88
|
46.8
|
43.1
|
88.1
|
72.6
|
75
|
|
NS08
|
70.8
|
64.6
|
55.3
|
54.5
|
49.9
|
71.9
|
71.8
|
75
|
|
NS09
|
67.1
|
|
53
|
64.5
|
59.1
|
69.6
|
69.5
|
75
|
|
NS10
|
65.9
|
|
55.7
|
63.4
|
58.4
|
68.6
|
68.4
|
75
|
|
NS11
|
87.5
|
|
72.4
|
|
49.5
|
87.6
|
87.5
|
75
|
|
NS12
|
73.1
|
|
58.7
|
|
54.4
|
73.4
|
73.2
|
75
|
|
NS13
|
76.3
|
55.7
|
54
|
|
50.7
|
76.4
|
76.4
|
75
|
|
NS14
|
72.5
|
59.4
|
51.6
|
|
48.8
|
72.7
|
72.7
|
75
|
|
NS15
|
66.1
|
60
|
49.4
|
|
45.7
|
67.2
|
67.1
|
75
|
|
NS16
|
81.4
|
60.2
|
49.2
|
|
46.4
|
81.5
|
81.5
|
75
|
|
NS17
|
79.8
|
70.4
|
|
|
43.7
|
80.3
|
80.3
|
75
|
|
NS18
|
71.3
|
71.4
|
|
|
43.9
|
74.4
|
74.4
|
75
|
|
NS19
|
71.3
|
56
|
|
|
40.5
|
71.5
|
71.5
|
75
|
|
NS20
|
73.8
|
62.9
|
|
|
|
74.2
|
74.2
|
75
|
|
NS21
|
63.8
|
63.6
|
|
|
|
66.7
|
66.7
|
75
|
|
NS22
|
69.4
|
64.7
|
|
|
|
70.7
|
70.7
|
75
|
|
NS23
|
72.5
|
64.5
|
|
|
|
73.1
|
73.1
|
75
|
|
NS24
|
77.3
|
56.4
|
48.6
|
|
|
77.4
|
77.4
|
75
|
|
NS25
|
79.8
|
|
56.2
|
|
|
79.9
|
79.9
|
75
|
|
NS26
|
87.5
|
|
51.7
|
|
|
87.5
|
87.5
|
75
|
|
NS27
|
79.8
|
|
66.8
|
|
|
80.1
|
79.9
|
75
|
|
NS28
|
77.3
|
|
88
|
|
|
88.3
|
77.4
|
75
|
|
NS30
|
73.8
|
|
68
|
|
|
74.8
|
73.8
|
75
|
|
NS31
|
84.5
|
60.7
|
|
|
|
84.5
|
84.5
|
75
|
|
NS32
|
73.8
|
|
60.9
|
|
54.6
|
74.1
|
73.9
|
75
|
|
NS34
|
85.9
|
|
55.9
|
|
51.8
|
85.9
|
85.9
|
75
|
|
NS35
|
83.4
|
68.8
|
|
|
41
|
83.5
|
83.5
|
75
|
|
NS36
|
77.3
|
81.5
|
|
|
41
|
82.9
|
82.9
|
75
|
|
NS37
|
68.6
|
68.9
|
|
|
40.6
|
71.8
|
71.8
|
75
|
|
NS38
|
64.8
|
63.3
|
|
|
40.2
|
67.1
|
67.1
|
75
|
|
NS39
|
72.5
|
65.4
|
|
|
|
73.3
|
73.3
|
75
|
|
NS40
|
70.3
|
74.6
|
|
|
|
76
|
76
|
75
|
|
NS41
|
71.3
|
67
|
|
|
|
72.7
|
72.7
|
75
|
|
NS42
|
83.4
|
|
58.4
|
|
|
83.4
|
83.4
|
75
|
|
NS43
|
67.1
|
|
69.9
|
|
|
71.8
|
67.2
|
75
|
|
NS44
|
66.5
|
|
88
|
|
|
88
|
66.6
|
75
|
|
NS45
|
79.8
|
61.3
|
|
|
42.2
|
79.9
|
79.9
|
75
|
|
NS46
|
83.4
|
64.2
|
|
|
41.5
|
83.4
|
83.4
|
75
|
|
NS47
|
79.8
|
|
82
|
|
64.4
|
84.1
|
80
|
75
|
|
NS48
|
75.4
|
|
54.2
|
|
50.6
|
75.5
|
75.5
|
75
|
|
NS50
|
65.3
|
66.8
|
|
|
43.8
|
69.1
|
69.1
|
75
|
|
NS51
|
83.4
|
57.8
|
|
|
43.2
|
83.4
|
83.4
|
75
|
|
NS52
|
75.4
|
71.5
|
|
|
42.7
|
76.9
|
76.9
|
75
|
|
NS53
|
75.4
|
70.5
|
|
|
42.5
|
76.6
|
76.6
|
75
|
|
NS54
|
81.4
|
57.7
|
|
|
|
81.5
|
81.5
|
75
|
|
NS55
|
77.3
|
|
|
|
|
77.4
|
77.4
|
75
|
|
NS56
|
83.4
|
|
|
|
|
83.4
|
83.4
|
75
|
|
NS57
|
83.4
|
|
|
|
|
83.4
|
83.4
|
75
|
|
NS58
|
74.6
|
|
|
|
|
74.6
|
74.6
|
75
|
|
NS59
|
76.3
|
|
|
|
|
76.3
|
76.3
|
75
|
|
NS60
|
79.8
|
|
|
|
|
79.9
|
79.9
|
75
|
|
NS61
|
77.3
|
|
|
|
|
77.4
|
77.4
|
75
|
|
NS64
|
85.4
|
|
69.9
|
|
61.9
|
86
|
85.9
|
75
|
|
NS65
|
73.8
|
|
61.2
|
|
55.6
|
74.2
|
73.9
|
75
|
|
NS66
|
89.4
|
|
53.7
|
|
50.4
|
89.4
|
89.4
|
75
|
|
NS67
|
70.8
|
55.7
|
48.1
|
|
45.3
|
71
|
70.9
|
75
|
|
NS68
|
85.9
|
56.6
|
|
|
44.7
|
85.9
|
85.9
|
75
|
|
NS69
|
72.5
|
73.2
|
|
|
41.8
|
75.9
|
75.9
|
75
|
|
NS70
|
73.8
|
73.9
|
|
|
41.1
|
76.9
|
76.9
|
75
|
|
NS71
|
70.3
|
67.9
|
|
|
41.2
|
72.3
|
72.3
|
75
|
|
NS72
|
87.5
|
56
|
|
|
|
87.5
|
87.5
|
75
|
|
NS73
|
73.8
|
54.9
|
|
|
|
73.9
|
73.9
|
75
|
|
NS19a
|
81.4
|
55.4
|
|
|
|
81.4
|
81.4
|
75
|
|
NS19b
|
81.4
|
55.5
|
|
|
|
81.4
|
81.4
|
75
|
|
NS19c
|
72.5
|
54.7
|
|
|
|
72.6
|
72.6
|
75
|
|
NS37a
|
78.5
|
64
|
|
|
|
78.7
|
78.7
|
75
|
|
NS37b
|
89.4
|
60.8
|
|
|
|
89.4
|
89.4
|
75
|
|
NS39a
|
79.9
|
58.5
|
|
|
|
79.9
|
79.9
|
75
|
|
NS42a
|
79.8
|
|
|
|
|
79.9
|
79.9
|
75
|
|
NS48a
|
73.8
|
|
|
|
54.4
|
73.9
|
73.9
|
75
|
|
NS49a
|
83.4
|
|
50.8
|
|
52
|
83.4
|
83.4
|
75
|
|
NS52a
|
83.4
|
77.4
|
|
|
42.7
|
84.4
|
84.4
|
75
|
|
NS70a
|
87.5
|
71.4
|
|
|
40.9
|
87.6
|
87.6
|
75
|
|
NS74
|
73.8
|
|
|
|
46.8
|
73.9
|
73.9
|
75
|
|
NS49b
|
69.8
|
56.7
|
|
|
|
70
|
70
|
65[3] (70)
|
|
NS76
|
85.9
|
60.9
|
|
|
|
85.9
|
85.9
|
75
|
|
NS76b
|
77.3
|
60.8
|
|
|
|
77.4
|
77.4
|
75
|
Note:
[1] For sewer construction, the
noise level represents the highest of the group activities of the Open Trench
Method, Pipe Jacking Method and Road Pavement and Finish Works
[2]
The construction of Sewage Pumping Station is 300m away from the NSR. Hence,
the impact of SPS is not taken into account
[3]
For school, the noise limit is 70 dB(A). However, during examination, the noise
limit is 65 dB(A).
As shown
in Table 8.17, residual exceedance of noise levels (1 – 19 dB(A) higher than
the noise criteria) are still predicted at most NSRs. Since the dominated noise
impacts are originated from 274DS construction at some of the sensitive
receivers, it is suggested that the site construction works in the workfront of
NS01 – NS04, NS06, NS07, NS28 and NS44 should be scheduled before or after the
construction work of 274DS. With the rescheduling, the number of affected NSRs
will be reduced. In addition, sewer construction work and Sewage Pumping
Station construction should not be taken place concurrently. It will reduce the
noise levels at NS01, NS40, NS48, NS52 and NS70 to an acceptable level. In addition,
there should be no construction works
during the examination
periods of S49b.
Practical noise
abatement measures, such as the use of quieter plant, rescheduling of works to
avoid the concurrent undertaking of noise activities, the erection of temporary
noise barriers along site boundaries and the use of movable noise barriers /
enclosures, where practicable, have been considered in the project. However, as
shown in Table 8.14-8.17, exceedances of the daytime construction noise
criterion are still predicted at some of the NSRs located close to the
construction site.
The causes of the
noise exceedances are primarily from the construction of the sewers and rising
mains in which the noisiest activities are anticipated to be the Road Pavement
and Finishes Work, as mitigation measures such as moveable noise barriers could
not be deployed due to practical constraints.
Pipe Jacking
technique has been explored. However, due to the constraint of underground
pipeline and utilities, this method is not practical.
Due to the nature
of the construction work, it is envisaged that the exceedances are likely
limited only to time periods when the construction work is being carried out
adjacent to the NSRs (within a radius of about 50m). It is anticipated that the
sewers and the rising mains will be constructed in segments of up to a maximum
of 50m in length at any one time, and therefore the impacts would only last for
a relatively short period of time. Table 8.18 summarizes the construction
period of each type of construction activities.
Table
8.18: Construction period of
different construction activities
|
Construction
Activities for each 50m segment
|
Construction
Period
|
|
Site Preparation
|
0.5 month
|
|
Sewer laying Work
|
1 – 2 weeks
|
|
Road Surfacing Work
|
1 – 2 day
|
However, the
progress of works is subject to other variables, such as inclement weather,
conflicts with existing utilities and restrictions on road closure during peak
hours. Beyond a distance of 50m, the cumulative noise levels arising from the
sewer construction works and pumping station construction work will be reduced
to within the daytime construction noise limit.
The extent and
duration of the predicted residual impacts are summarized in Table 8.19 – 8.23.
In addition, the approximate number of dwellings being affected by the residual
impacts is also indicated.
Tin
Shui Wai Area (2A-1T)
Table
8.19: Predicted residual impact at the representative NSRs with
mitigation measures
|
NSR
|
Max
Residual Noise Level dB(A)
|
Activities
|
No. of dwelling affected
|
|
Sewer Construction
|
Road Surfacing
|
|
Site Preparation
(SWL:104)
|
Road Opening
(SWL:100)
|
Trench Excavat-ion / Earth Work
(SWL:102)
|
Sewage Laying
(SWL:105.5)
|
Finishes
(SWL:106.4)
|
Ballast Laying/ Concrete Compact-ion
(SWL:105)
|
Road Pave-ment
(SWL:106)
|
|
G1
|
G2
|
G3
|
G4
|
G5
|
G6a
|
G6b
|
|
Duration
|
|
2 weeks
|
1 weeks
|
2 weeks
|
2 days
|
2 days
|
1 - 2 days
|
1 - 2 days
|
|
Residual Noise Level of Individual Activity, dB(A)
|
|
NT16
|
83.4
|
81.0
|
77.0
|
79.0
|
82.5
|
83.4
|
82.0
|
83.0
|
9
|
|
NT17
|
81.4
|
79.0
|
75.0
|
77.0
|
80.5
|
81.4
|
80.0
|
81.0
|
3
|
|
NT18
|
79.8
|
77.4
|
73.4
|
75.4
|
78.9
|
79.8
|
78.4
|
79.4
|
9
|
|
NT20
|
81.4
|
79.0
|
75.0
|
77.0
|
80.5
|
81.4
|
80.0
|
81.0
|
15
|
|
NT21
|
81.4
|
79.0
|
75.0
|
77.0
|
80.5
|
81.4
|
80.0
|
81.0
|
52
|
|
NT22
|
79.8
|
77.4
|
73.4
|
75.4
|
78.9
|
79.8
|
78.4
|
79.4
|
15
|
|
NT24
|
79.8
|
77.4
|
73.4
|
75.4
|
78.9
|
79.8
|
78.4
|
79.4
|
6
|
|
NT22a
|
79.8
|
77.4
|
73.4
|
75.4
|
78.9
|
79.8
|
78.4
|
79.4
|
9
|
|
NT24a
|
81.4
|
79.0
|
75.0
|
77.0
|
80.5
|
81.4
|
80.0
|
81.0
|
25
|
Lau Fau Shan Area (Alternative 2A-3T)
Table
8.20: Predicted residual noise level at the representative NSRs
with mitigation measures
|
NSR
|
Max
Residual Noise Level dB(A)
|
Activities
|
No. of dwelling affected
|
|
Sewer Construction
|
Road Surfacing
|
|
Site Preparation
(SWL:
104)
|
Road Opening
(SWL:100)
|
Trench Excavat-ion / Earth Work
(SWL:102)
|
Sewage Laying
(SWL:105.5)
|
Finishes
(SWL:106.4)
|
Ballast Laying/ Concrete Compact-ion
(SWL:105)
|
Road Pave-ment
(SWL:106)
|
|
G1
|
G2
|
G3
|
G4
|
G5
|
G6a
|
G6b
|
|
Duration
|
|
2 weeks
|
1 weeks
|
2 weeks
|
2 days
|
2 days
|
1 - 2 days
|
1 - 2 days
|
|
Residual Noise Level of Individual Activity, dB(A)
|
|
NL13
|
80.3
|
77.9
|
73.9
|
75.9
|
79.4
|
80.3
|
78.9
|
79.9
|
3
|
|
NL22
|
77.4
|
75.0
|
71.0
|
73.0
|
76.5
|
77.4
|
76.0
|
77.0
|
9
|
|
NL29
|
76.5
|
74.1
|
70.1
|
72.1
|
75.6
|
76.5
|
75.1
|
76.1
|
3
|
|
NP01
|
81.4
|
79.0
|
75.0
|
77.0
|
80.5
|
81.4
|
80.0
|
81.0
|
3
|
Ngau Tam Mei and San Tin Areas (2A-2T and 2B-1T)
Table
8.21: Predicted residual noise level at the representative NSRs
with mitigation measures
|
NSR
|
Max
Residual Noise Level dB(A)
|
Activities
|
No. of dwelling affected
|
|
Sewer Construction
|
Road Surfacing
|
|
Site Preparation
(SWL:104)
|
Road Opening
(SWL:100)
|
Trench Excavat-ion / Earth Work
(SWL:102)
|
Sewage Laying
(SWL:105.5)
|
Finishes
(SWL:106.4)
|
Ballast Laying/ Concrete Compact-ion
(SWL:105)
|
Road Pave-ment
(SWL:106)
|
|
G1
|
G2
|
G3
|
G4
|
G5
|
G6a
|
G6b
|
|
Duration
|
|
2 weeks
|
1 weeks
|
2 weeks
|
2 days
|
2 days
|
1 - 2 days
|
1 - 2 days
|
|
Residual Noise Level of Individual Activity, dB(A)
|
|
NN02
|
85.9
|
83.5
|
79.5
|
81.5
|
85.0
|
85.9
|
84.5
|
85.5
|
51
|
|
NN09
|
79.9
|
77.5
|
73.5
|
75.5
|
79.0
|
79.9
|
78.5
|
79.5
|
28
|
|
NN13
|
78.5
|
76.1
|
72.1
|
74.1
|
77.6
|
78.5
|
77.1
|
78.1
|
5
|
|
NN14
|
81.4
|
79.0
|
75.0
|
77.0
|
80.5
|
81.4
|
80.0
|
81.0
|
3
|
|
NN17
|
79.2
|
76.8
|
72.8
|
74.8
|
78.3
|
79.2
|
77.8
|
78.8
|
9
|
|
NN21
|
76.3
|
73.9
|
69.9
|
71.9
|
75.4
|
76.3
|
74.9
|
75.9
|
15
|
|
NN22
|
78.5
|
76.1
|
72.1
|
74.1
|
77.6
|
78.5
|
77.1
|
78.1
|
33
|
|
NN24
|
78.5
|
76.1
|
72.1
|
74.1
|
77.6
|
78.5
|
77.1
|
78.1
|
7
|
|
NN25
|
81.4
|
79.0
|
75.0
|
77.0
|
80.5
|
81.4
|
80.0
|
81.0
|
72
|
|
NN26
|
78.5
|
76.1
|
72.1
|
74.1
|
77.6
|
78.5
|
77.1
|
78.1
|
3
|
|
NN27
|
78.5
|
76.1
|
72.1
|
74.1
|
77.6
|
78.5
|
77.1
|
78.1
|
6
|
|
NN43
|
76.3
|
73.9
|
69.9
|
71.9
|
75.4
|
76.3
|
74.9
|
75.9
|
2
|
|
NN45
|
85.9
|
83.5
|
79.5
|
81.5
|
85.0
|
85.9
|
84.5
|
85.5
|
27
|
|
NN46
|
89.4
|
87.0
|
83.0
|
85.0
|
88.5
|
89.4
|
88.0
|
89.0
|
21
|
|
NN47
|
89.4
|
87.0
|
83.0
|
85.0
|
88.5
|
89.4
|
88.0
|
89.0
|
18
|
|
NN50
|
78.5
|
76.1
|
72.1
|
74.1
|
77.6
|
78.5
|
77.1
|
78.1
|
6
|
|
NN51
|
79.8
|
77.4
|
73.4
|
75.4
|
78.9
|
79.8
|
78.4
|
79.4
|
9
|
|
NN52
|
80.6
|
78.2
|
74.2
|
76.2
|
79.7
|
80.6
|
79.2
|
80.2
|
6
|
|
NN19a
|
77.3
|
74.9
|
70.9
|
72.9
|
76.4
|
77.3
|
75.9
|
76.9
|
9
|
|
NN26a
|
78.5
|
76.1
|
72.1
|
74.1
|
77.6
|
78.5
|
77.1
|
78.1
|
5
|
Note [1]:
Erection of 3m barrier in front of house
San Lung Tsuen Area (2B-2T)
Table 8.22: Predicted residual noise level
at the representative NSRs with mitigation measures
|
NSR
|
Max
Residual Noise Level dB(A)
|
Activities
|
No. of dwelling affected
|
|
Sewer Construction
|
Road Surfacing
|
|
Site Preparation
|
Road Opening
(SWL:100)
|
Trench Excavation
|
Sewage Laying
|
Earth
Work
(SWL:
101 )
|
Finishes (SWL:100)
|
Ballast Laying/ Concrete Compact-ion
(SWL:100)
|
Road Pave-ment
(SWL:
105.3)
|
|
G1
|
G2
|
G3
|
G4
|
G5
|
G6
|
G6a
|
G6b
|
|
Duration
|
|
2 weeks
|
1 weeks
|
3 weeks
|
2 weeks
|
1 Week
|
2 days
|
1 - 2 days
|
1 - 2 days
|
|
Residual Noise Level of Individual Activity, dB(A)
|
|
NN31a
|
80
|
No
piling oscillator
|
74.7
|
No
excavator for trench
|
Manual
|
75.7
|
74.7
|
74.7
|
80.0
|
1
|
|
NN32
|
84
|
78.7
|
79.7
|
78.7
|
78.7
|
84.0
|
3
|
|
NN33
|
86.5
|
81.2
|
82.2
|
81.2
|
81.2
|
86.5
|
18
|
|
NN35
|
86.5
|
81.2
|
82.2
|
81.2
|
81.2
|
86.5
|
9
|
|
NN36
|
79.3
|
74.0
|
75
|
74.0
|
74.0
|
79.3
|
15
|
|
NN38
|
79.3
|
74.0
|
75
|
74.0
|
74.0
|
79.3
|
24
|
|
NN39
|
86.7
|
81.4
|
82.4
|
81.4
|
81.4
|
86.7
|
1
|
|
NN40
|
86.8
|
81.5
|
82.5
|
81.5
|
81.5
|
86.8
|
3
|
|
|
|
|
|
|
|
|
|
|
|
|
Shap Pat Heung Area (2B-2T)
Table 8.23: Predicted
residual noise level at the representative NSRs with mitigation measures
|
NSR
|
Max
Residual Noise Level dB(A)
|
Activities
|
No. of dwelling affected
|
|
Sewer Construction
|
Road Surfacing
|
|
Site Preparation
(SWL:104)
|
Road Opening
(SWL:100)
|
Trench Excavat-ion / Earth Work
(SWL:102)
|
Sewage Laying
(SWL:105.5)
|
Finishes
(SWL:106.4)
|
Ballast Laying/ Concrete Compact-ion
(SWL:105)
|
Road Pave-ment
(SWL:106)
|
|
G1
|
G2
|
G3/G5
|
G4
|
G6
|
R1/R2
|
R3
|
|
Duration
|
|
2
weeks
|
1
weeks
|
2
weeks
|
2
days
|
2
days
|
1
- 2 days
|
1
- 2 days
|
|
Residual
Noise Level of Individual Activity, dB(A)
|
|
NS01
|
75.5
|
73.1
|
69.1
|
71.1
|
74.6
|
75.5
|
74.1
|
75.1
|
3
|
|
NS11
|
87.5
|
85.1
|
81.1
|
83.1
|
86.6
|
87.5
|
86.1
|
87.1
|
2
|
|
NS13
|
76.4
|
74
|
70
|
72
|
75.5
|
76.4
|
75
|
76
|
18
|
|
NS16
|
81.5
|
79.1
|
75.1
|
77.1
|
80.6
|
81.5
|
80.1
|
81.1
|
24
|
|
NS17
|
80.3
|
77.9
|
73.9
|
75.9
|
79.4
|
80.3
|
78.9
|
79.9
|
12
|
|
NS24
|
77.4
|
75
|
71
|
73
|
76.5
|
77.4
|
76
|
77
|
45
|
|
NS25
|
79.9
|
77.5
|
73.5
|
75.5
|
79
|
79.9
|
78.5
|
79.5
|
21
|
|
NS26
|
87.5
|
85.1
|
81.1
|
83.1
|
86.6
|
87.5
|
86.1
|
87.1
|
6
|
|
NS27
|
79.9
|
77.5
|
73.5
|
75.5
|
79
|
79.9
|
78.5
|
79.5
|
15
|
|
NS28
|
77.4
|
75
|
71
|
73
|
76.5
|
77.4
|
76
|
77
|
3
|
|
NS31
|
84.5
|
82.1
|
78.1
|
80.1
|
83.6
|
84.5
|
83.1
|
84.1
|
3
|
|
NS34
|
85.9
|
83.5
|
79.5
|
81.5
|
85
|
85.9
|
84.5
|
85.5
|
15
|
|
NS35
|
83.5
|
81.1
|
77.1
|
79.1
|
82.6
|
83.5
|
82.1
|
83.1
|
15
|
|
NS36
|
82.9
|
80.5
|
76.5
|
78.5
|
82
|
82.9
|
81.5
|
82.5
|
9
|
|
NS40
|
76
|
73.6
|
69.6
|
71.6
|
75.1
|
76
|
74.6
|
75.6
|
24
|
|
NS42
|
83.4
|
81
|
77
|
79
|
82.5
|
83.4
|
82
|
83
|
24
|
|
NS45
|
79.9
|
77.5
|
73.5
|
75.5
|
79
|
79.9
|
78.5
|
79.5
|
18
|
|
NS46
|
83.4
|
81
|
77
|
79
|
82.5
|
83.4
|
82
|
83
|
9
|
|
NS47
|
80
|
77.6
|
73.6
|
75.6
|
79.1
|
80
|
78.6
|
79.6
|
33
|
|
NS48
|
75.5
|
73.1
|
69.1
|
71.1
|
74.6
|
75.5
|
74.1
|
75.1
|
21
|
|
NS51
|
83.4
|
81
|
77
|
79
|
82.5
|
83.4
|
82
|
83
|
18
|
|
NS52
|
76.9
|
74.5
|
70.5
|
72.5
|
76
|
76.9
|
75.5
|
76.5
|
33
|
|
NS53
|
76.6
|
74.2
|
70.2
|
72.2
|
75.7
|
76.6
|
75.2
|
76.2
|
9
|
|
NS54
|
81.5
|
79.1
|
75.1
|
77.1
|
80.6
|
81.5
|
80.1
|
81.1
|
27
|
|
NS55
|
77.4
|
75
|
71
|
73
|
76.5
|
77.4
|
76
|
77
|
63
|
|
NS56
|
83.4
|
81
|
77
|
79
|
82.5
|
83.4
|
82
|
83
|
18
|
|
NS57
|
83.4
|
81
|
77
|
79
|
82.5
|
83.4
|
82
|
83
|
24
|
|
NS59
|
76.3
|
73.9
|
69.9
|
71.9
|
75.4
|
76.3
|
74.9
|
75.9
|
33
|
|
NS60
|
79.9
|
77.5
|
73.5
|
75.5
|
79
|
79.9
|
78.5
|
79.5
|
15
|
|
NS61
|
77.4
|
75
|
71
|
73
|
76.5
|
77.4
|
76
|
77
|
12
|
|
NS64
|
85.9
|
83.5
|
79.5
|
81.5
|
85
|
85.9
|
84.5
|
85.5
|
39
|
|
NS66
|
89.4
|
87
|
83
|
85
|
88.5
|
89.4
|
88
|
89
|
27
|
|
NS68
|
85.9
|
83.5
|
79.5
|
81.5
|
85
|
85.9
|
84.5
|
85.5
|
52
|
|
NS69
|
75.9
|
73.5
|
69.5
|
71.5
|
75
|
75.9
|
74.5
|
75.5
|
3
|
|
NS70
|
76.9
|
74.5
|
70.5
|
72.5
|
76
|
76.9
|
75.5
|
76.5
|
3
|
|
NS72
|
87.5
|
85.1
|
81.1
|
83.1
|
86.6
|
87.5
|
86.1
|
87.1
|
39
|
|
NS19a
|
81.4
|
79
|
75
|
77
|
80.5
|
81.4
|
80
|
81
|
12
|
|
NS19b
|
81.4
|
79
|
75
|
77
|
80.5
|
81.4
|
80
|
81
|
27
|
|
NS37a
|
78.7
|
76.3
|
72.3
|
74.3
|
77.8
|
78.7
|
77.3
|
78.3
|
9
|
|
NS37b
|
89.4
|
87
|
83
|
85
|
88.5
|
89.4
|
88
|
89
|
12
|
|
NS39a
|
79.9
|
77.5
|
73.5
|
75.5
|
79
|
79.9
|
78.5
|
79.5
|
21
|
|
NS42a
|
79.9
|
77.5
|
73.5
|
75.5
|
79
|
79.9
|
78.5
|
79.5
|
18
|
|
NS49a
|
83.4
|
81
|
77
|
79
|
82.5
|
83.4
|
82
|
83
|
12
|
|
NS52a
|
84.4
|
82
|
78
|
80
|
83.5
|
84.4
|
83
|
84
|
9
|
|
NS70a
|
87.6
|
85.2
|
81.2
|
83.2
|
86.7
|
87.6
|
86.2
|
87.2
|
18
|
|
NS76
|
85.9
|
83.5
|
79.5
|
81.5
|
85
|
85.9
|
84.5
|
85.5
|
12
|
|
NS76b
|
77.4
|
75
|
71
|
73
|
76.5
|
77.4
|
76
|
77
|
24
|
Note [1]:
Erection of 3m barrier in front of house
The recommended mitigation measures, monitoring procedures
and locations are presented in detail in the Environmental Monitoring and Audit
(EM&A) Manual. The effectiveness of on-site control measures could also be
evaluated through the monitoring. All the recommended mitigation measures
should be incorporated into the EM&A programme for implementation during
construction.
Noise from pumping stations will be considered as fixed
noise source. In accordance with Annex
5 of TM-EIAO, fixed plant noise levels should be 5dB(A) below the appropriate
Acceptable Noise Levels (ANLs) or the prevailing noise level, whichever is the
lowest. These noise limits apply to
uses, which rely on open windows for ventilation.
The prevailing noise levels at the closest representative
sensitive receivers in the nearby areas have been measured during daytime and
nighttime to establish the appropriate noise criteria. A summary of the noise limits for the fixed
plant is given in Table 9.1.
Table 9.1: Noise criteria for fixed plant source
|
|
Noise Limit, Leq, 30 min dB(A)
|
|
Pumping Station Location
|
Prevailing Background[3]
|
Night Time
|
Adopted Noise Criteria
|
|
Ngau Tam Mei and San
Tin ( Package 2A-2T and 2B-1T)
|
|
Ngau Tam Mei Sewage
Pumping Station
|
68.5 (at NN08)
|
50 (ASR B)
|
50
|
|
Tam Mei Barrack Sewage
Pumping Station
|
54 (at NN15)
|
45
|
45
|
|
San Tin Sewage Pumping
Station
|
51 (at NN29)
|
50 (ASR B)
|
50
|
|
San Lung Tsuen Sewage
Pumping Station
|
68.1 (at NN41)
|
45
|
45
|
|
San Tin Barracks
Sewage Pumping Station
|
52 (at NN50)
|
45
|
45
|
|
Yuen Long South
(Package 2B-2T)
|
|
Shan Ha Tsuen Pumping Station
|
55.3 (at NS04)
|
45
|
45
|
|
Mui Kiu Tau Tsuen Pumping station
|
50.6 (at NS18)
|
45
|
45
|
|
Pak Sha Tsuen Pumping Station
|
52.7 (at NS21)
|
45
|
45
|
|
Sham Chung Tsuen
Sewage Pumping Station
|
55.9 (at NS36)
|
45
|
45
|
|
Shui Tsiu San Tsuen
Sewage Pumping Station
|
53.1 (at NS40)
|
45
|
45
|
|
Shung Ching San Tsuen
Sewage Pumping Station
|
61.7 (at NS52a)
|
45
|
45
|
|
Nga Yiu Tau Sewage
Pumping Station
|
55.3 (at NS70)
|
45
|
45
|
|
Lau Fau Shan and Mong
Tseng (Package 2A-3T)
|
|
Lau Fau Shan Sewage
Pumping Station
|
51.7 (at NL04)
|
45
|
45
|
|
Mong Tseng Sewage
Pumping Station
|
55.2 (at NL26)
|
45
|
45
|
|
Yuen Long (Package 2A-1T and the alternatives)
|
|
Sewage Pumping Station
near the Yuen Long STW
|
54.3 near Ng UK Tsuen (> 300m from STW)
|
50 (ASR B)
|
50
|
Note [1]:
Night time: 2300 to 0700 hours
[2]: ANL –5dB(A) or prevailing background noise levels,
whichever is lower
[3]: Measured at the closest representative receivers
As the prevailing background level is greater than the
nighttime noise criteria stipulated in TM-EIAO, these noise criteria are
adopted as the noise limit.
The background noise environment for most of the
surrounding areas is generally tranquil except for Yuen Long Industrial Area
and areas located along major roads, in particular the Yuen Long Highway, Route
3, San Tin Highway and Castle Peak Road, Lau Fau Shan Road and Ping Ha
Road. In Yuen Long Industrial Area, the
background noise environment generally consists of noise from industrial
operation. Prevailing noise levels in
terms of Leq have been measured at the NSRs close to the SPSs to
determine the appropriate noise criteria.
The characteristics of nearby noise sensitive receivers in the vicinity
of the pumping stations are summarized in Table 9.2.
Table
9.2: Characteristics of nearby
environment in the vicinity of the Sewage Pumping Stations
|
Pumping Station
|
Description
|
Characteristics
of nearby land use
|
ASR
|
Influencing
Factors
|
|
Ngau Tam Mei and San
Tin ( Package 2A-2T and 2B-1T)
|
|
P1
|
Ngau Tam Mei Sewage
Pumping Station
|
Village Type
Development
|
B
|
San Tin Highway
|
|
P2
|
Tam Mei Barrack Sewage
Pumping Station
|
Barrack,
Village Type
Development
|
A
|
|
|
P3
|
San Tin Sewage Pumping
Station
|
Village Type Development
and Residential (Group D) (S/YL-ST/5)
|
B
|
San Tin Highway
|
|
P4
|
San Lung Tsuen Sewage
Pumping Station
|
Village Type
Development
|
A
|
|
|
P5
|
San Tin Barracks
Sewage Pumping Station
|
Village Type
Development
|
A
|
|
|
Yuen Long (Package 2A-1T and the alternatives)
|
|
OP1
|
Sewage Pumping Station
near the Yuen Long STW
|
No sensitive receivers
within 300m
|
-----
|
Yuen Long Industrial
Estate
|
|
Lau Fau Shan and Mong
Tseng (Package 2A-3T)
|
|
A1
|
Lau Fau Shan Sewage
Pumping Station
|
Village Type
Development
|
A
|
|
|
A2
|
Mong Tseng Sewage
Pumping Station
|
Village Type
Development
|
A
|
|
|
Yuen Long South
(Package 2B-2T)
|
|
B1
|
Shan Ha Tsuen Sewage
Pumping Station
|
Village Type
Development
|
A
|
|
|
B2
|
Muk Kiu Tau Tsuen
Sewage Pumping Station
|
Village Type
Development
|
A
|
|
|
B3
|
Sham Chung Tsuen
Sewage Pumping Station
|
Residential (Group D)
|
A
|
|
|
B4
|
Shui Tsiu San Tsuen
Sewage Pumping Station
|
Village Type
Development
|
A
|
|
|
B5
|
Shung Ching San Tsuen
Sewage Pumping Station
|
Village Type
Development
|
A
|
|
|
B6
|
Nga Yiu Tau Sewage
Pumping Station
|
Residential (Group D) & Village Type (S/YL-TT/10)
|
A
|
|
|
B7
|
Pak Sha Tsuen Sewage
Pumping Station
|
Village Type
Development
|
A
|
|
Representative NSRs within 300m of the sewage pumping
stations are given in Appendix 8.3 and shown in Figures 8.1 to 8.3. The assessment will focus on the first layer
of NSRs that have direct line of sight to the proposed works. NSRs that are screened off by substantial
barriers such as buildings are not included.
The area sensitivity rating of the NSR is determined according to TM-NCO
and they are shown in Table 9.2.
The potential noise sources for a standard pumping station
include extraction fans, deodourisation system and operation of air valves in
the rising mains.
The major operational noise sources are from the pumping
facilities. The sound power level of
the pumping facilities can be determined by the CIBSE Guide, ASHARE Handbook or
measurement on similar pumping station.
However, as detailed information such as the number and location of
extraction fans, location of air valves and building layout is currently
unavailable, detailed noise calculations could not be undertaken.
In order to ensure the operation of the standard pumping
station will comply with the TM-EIAO noise criteria, the maximum permissible
SWL at the louvre of the pumping station is calculated based on the measured
distance to the closest NSRs. As a
conservative approach, a -6 dB tonal correction and a -3 dB façade correction
have been applied in accordance with the TM-NCO. A hemispherical radiation model is adopted to determine the
permissible SWL. In addition, on
applying the above backward assessment, the cumulative impact from active
concurrent projects in the vicinity of the pumping station is also taken into
account.
Based on the methodology as described in Section 9.5, the
maximum permissible SWLs at the louvres of the pumping station are calculated
based on the noise criteria and measured distance from the closest NSRs. The recommended maximum permissible SWLs for
the proposed SPS are presented in Tables 9.3 – 9.5.
9.6.1 Tin Shui Wai and Yuen Long
Areas (Alternative 2A-1T)
There is no pumping station proposed in
the Tin Shui Wai Area. For the Yuen Long Effluent Pumping Station, there are no noise
sensitive receivers identified within 300m in the vicinity of the site.
Therefore, no operational noise impact is anticipated for this area.
9.6.2 Ngau Tam Mei and San Tin Areas (2A-2T and 2B-1T)
The permissible SWL for the Pumping Stations in
Ngau Tam Mei and San Tin Areas are summarized in Table 9.3.
Table
9.3: Permissible sound power level (SWL) for the proposed sewage pumping
station in Ngau Tam Mei and San Tin Area
|
Pumping Stations
|
NSR No.
|
Distance from pumping station[1] (m)
|
Night-time Noise Criteria[2]
|
Permissible SWL at the Louvre dB(A)[4,5]
|
|
Ngau Tam Mei Pumping Station
|
NN08
|
52
|
50
|
83.3
|
|
Tam Mei Barrack Pumping Station
|
NN15
|
24
|
45
|
71.6
|
|
San Tin Pumping Station
|
NN29
|
67.5
|
50
|
85.6
|
|
San Lung Tsuen Pumping Station
|
NN41
|
14
|
45
|
66.9
|
|
Cassino Line Pumping Station[3]
|
NN50
|
32
|
45
|
74.1
|
Note: [1]
Distance is estimated from notional source to the façade of the NSR
[2] As the pumping station
will operate 24 hour, the night time noise level is selected.
[3]:Cassino Line Pumping
Station is inside San Tin Barrack. Due to security reason, the land use inside
the San Tin Barrack cannot be disclosed. The closest buildings inside the
Barrack are thus assumed as the NSR
[4] It is assumed that there is no intermittent effect. The detail designer should further review
the fan/pump specification and make suitable adjustment.
[5] SWL = Noise Criteria +10log(2p(distance)2)-
6 (tonal effect) –3 (façade effect)
9.6.3 Lau Fau Shan and Mong Tseng Areas (2A-3T)
The permissible SWL for the Pumping Stations in Lau
Fau Shan and Mong Teng Areas are summarized in Table 9.4.
Table
9.4: Permissible sound power level (SWL) for the proposed sewage pumping
station in Lau Fau Shan and Mong Tseng Areas
|
Pumping Stations
|
NSR No.
|
Distance from pumping station[1] (m)
|
Night-time Noise Criteria[2]
|
Permissible SWL at the Louvre dB(A) [3,4]
|
|
Lau Fau Shan Pumping Station
|
NL04
|
74
|
45
|
81.4
|
|
Mong Tseng Pumping Station
|
NL26
|
28
|
45
|
72.9
|
Note [1]
Distance is estimated from notional source to the façade of the NSR
[2]
As the pumping station will operate 24 hour, the night time noise level is
selected.
[3] It is assumed that there is no intermittent effect. The detail designer should further review
the fan/pump specification and make suitable adjustment.
[4] SWL = Noise Criteria +10log(2p(distance)2)-
6 (tonal effect) –3 (façade effect)
9.6.4 Shap Pat Heung Area (2B-2T)
The permissible SWL for the Pumping Stations in
Shap Pat Heung Area are summarized in Table 9.5.
Table
9.5: Permissible sound power level (SWL) for the proposed sewage pumping
station
|
NSR No.
|
NSR No.
|
Distance from pumping station[1] (m)
|
Night-time Noise Criteria[2]
|
Permissible SWL at the Louvre dB(A)[3,4]
|
|
Shan Ha Tsuen Pumping Station
|
NS04
|
28
|
45
|
72.9
|
|
Mui Kui Tau Tsuen Pumping Station
|
NS18
|
32
|
45
|
74.1
|
|
Pak Sha Tsuen Pumping Station
|
NS21
|
16
|
45
|
68.1
|
|
Sham Chung Tsuen Pumping Station
|
NS36
|
10
|
45
|
64.0
|
|
Shui Tsiu San Tsuen Pumping Station
|
NS40
|
22
|
45
|
70.8
|
|
Shung Ching San Tsuen Pumping Station
|
NS52a
|
16
|
45
|
68.1
|
|
Nga Yiu Tau Tsuen Pumping Station
|
NS70
|
24
|
45
|
71.6
|
Note [1]
Distance is estimated from notional source to the façade of the NSR
[2]
As the pumping station will operate 24 hour, the night time noise level is
selected.
[3] It is assumed that there
is no intermittent effect. The detail
designer should further review the fan/pump specification and make suitable
adjustment.
[4] SWL = Noise Criteria +10log(2p(distance)2)-
6 (tonal effect) –3 (façade effect)
Tables 9.3 – 9.5 give the permissible SWL at the louvre of
the pumping station. It will adopted as the pump room noise design criterion in
the contractor specification.
With reference to the measurement carried out in the
existing Ha Tsuen Sewage Pumping Station (see Table A5-1 in Annex A of the EIA
report of YLKTSSDS-1 ), a noise level of 81 dB(A) was measured at 1m from the
louvre opening (which is equivalent to Sound Power Level of 94dB(A) at Louvre
on assuming area source of louve size
of 1.65m ´
1.65m , SWL = Measured SPL + 10log(Conformal surface), where the conformal
surface at 1m is approximate 19.4m2 ). According to the EIA report of YLKTSSDS-1, the existing Ha Tsuen
SPS is currently without any acoustics treatment. In view of the above calculation, the recommended maximum
permissible SWLs are not particularly onerous and could be achieved by using
conventional plant with the adoption of proper acoustic treatments and building
design, where necessary. From
Table 9.3, Table 9.4 and 9.5, the lowest sound power level at louvre to be
achieved is 64dB(A), which is 30 dB(A) lower than that of the common Pumping
Station without mitigation measures. Table 9.6 proposes the mitigation measures
that are required in practice to reduce the noise levels.
Table
9.6: Proposed
Mitigation Measures for Pumping House
|
Sources
|
Proposed
Mitigation Measures
|
Reduction
dB(A)
|
|
Fan
|
Acoustic
Enclosure
Silencer
at inlet and outlet
|
20
– 30
|
|
Pump
|
Acoustic
Enclosure
Anti-vibration
Spring Mount
|
20
– 30
|
|
Louvre
|
Acoustic
Lounre
|
10
– 20
|
By incorporating the above recommendations, the
recommended maximum permissible SWLs could be achieved and therefore adverse
noise impacts are not expected.
It is recommended that further noise assessment should be
carried out during the detailed design stage of the proposed sewage pumping
station to determine the type of mitigation measures required for meeting the
recommended maximum permissible SWLs. Basic building design such as to avoid
any opening or louvres facing the nearest NSR should always be considered.
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