3.1
Introduction
Yau Tong Bay Development Reclamation
3.1.1
Westwood Hong & Associates Ltd
(WHA) was commissioned to conduct an environmental noise impact assessment on
the proposed Yau Tong Bay Development Reclamation.
3.1.2
This report presents the
assessment criteria, methodology and results for the noise impact as per the
requirements stipulated in the relevant Technical Memorandums (TMs) issued
under the Noise Control Ordinance (NCO)[1] : the TM on EIA Process
(EIA-TM)[2], the TM on Noise from Construction Work other than
Percussive Piling (GW-TM)[3] , the TM on Noise from Construction
Work in Designated Areas (DA-TM)[4] and the TM on Noise from
Percussive Piling (PP-TM)[5].
Scope and Objectives of the EIA (noise)
3.1.3
The scope of the EIA will cover
all works proposed within the Study Area and any other works associated with
these developments outside the Study Area. The EIA study will cover the
combined impacts of all these works on the Noise Sensitive Receivers (NSRs) in
the vicinity in accordance with the requirements laid down in the TM. The scope
includes the following key work elements of the project:-
i) Reclamation of Yau Tong Bay
ii) Construction of seawall
iii) Diversion of existing
drainage outfall and provision of new stormwater drainage system
iv) Provision of new sewerage
system
v) Decommissioning of all
the marine lots which have the potential history of land contamination due to
ship building and repairing facilities
vi) Demolition of existing
building structures; and
vii) Provision of
infrastructure (e.g. access roads, waterworks, services and utilities, etc.)
3.1.4
The potential noise sources
from the site are identified as the following:-
·
Construction noise (including
reclamation works and demolition of existing buildings)
·
Vehicular movement on haul
roads.
3.2
Reclamation Site Location
3.2.1
The reclamation site for the
CDA (Comprehensive Development Area) adjoins Cha Kwo Ling Road to the north and east and,
Ko Fai Road to the south. The future Western Coast Road (WCR) will be
located to the west of the site and MTR Yau Tong Station to the east (Figures 3.1 and 3.2). The reclamation works cover about 18 hectares
comprising 14.2 hectares of Yau Tong Bay and 3.8 hectares seabed
areas of the existing Marine Lots.
Should the coastal alignment of the WCR eventually be revised, the EIA
reports need to be revised.
3.3
Assessment Criteria
3.3.1
Construction work should comply
with the requirements of the “Noise Control Ordinance” (NCO), the “Technical
Memorandum on Environmental Impact Assessment Process” (EIA-TM), “Technical
Memorandum on Noise from Construction Work other than Percussive Piling”
(GW-TM) and the “Technical Memorandum on Noise from Construction Work in
Designated Areas” (DA-TM). However, the entire reclamation site lies outside
the Designated Area and construction activities during restricted hours will
need to comply with EIA-TM only.
3.3.2
Noise standards for daytime
construction activities are given in Table 1B of the “Technical Memorandum on
Environmental Impact Assessment Process” (EIA-TM). The noise standards are dependent on the uses
of the NSRs. The day-time construction noise (on any day not being a Sunday or
general holiday) should be limited to 75dB(A) (Leq, 30-mins) at the sensitive
residential buildings with opened windows and, 70dB(A) and 65dB(A) (during examinations)
at the school and educational buildings in the neighbourhood, as given in Table 3.1. EIA-TM states that the
noise criteria for construction or decommissioning of designated projects,
shall be met as far as practicable. All practicable mitigation measures shall
be exhausted and the residual impacts are minimized.
Table 3.1 Acceptable Noise Levels For Day,
Evening and Night Periods
|
Noise Standards, dB(A), Leq (30 mins)
|
|
Uses
|
0700 to 1900 hours on any day not being a Sunday or general
holiday
|
1900 to 0700 hours or any time on Sundays or general holiday
|
|
All domestic premises
including temporary housing accommodation
|
75
|
(see Note 3)
|
|
Hotels and hostels
|
75
|
(see Note 3)
|
|
Educational institutions
including kindergartens, nurseries and all others where unaided voice
communication is required
|
70
65
(during exam.)
|
(see Note 3)
|
Note
3: The criteria laid down in the relevant
technical memoranda under the Noise Control Ordinance for designated areas and
construction works other than percussive piling may be used for planning
purpose. A Construction Noise Permit (CNP) shall be required for the carrying
out of the construction work during the period.
3.3.3
GW-TM will cover the use of
specified powered mechanical equipment (PME) including barge mounted cranes,
barges, grab dredgers, dumpers, excavators, hydraulic rock drills, tug boats,
etc.
3.3.4
DA-TM governs construction
works to be carried out within a Designated Area during restricted hours. It
covers Prescribed Construction works including erection or dismantling of
formwork or scaffolding; loading, unloading or handling of rubble, wooden
boards, steel bars, wood or scaffolding material; and hammering. As the entire
reclamation site lies outside the Designated Areas, DA-TM does not apply.
Construction activities during restricted hours will need to comply with GW-TM
only.
3.3.5
A Construction Noise Permit (CNP)
is required for any construction work carried out during the night-time (2300
to 0700 hours), evening (1900 to 2300 hours) and any time on general holidays,
including Sunday.
3.3.6
The control of percussive
piling is governed at all times by “Technical Memorandum on Noise From
Percussive Piling” (PP-TM).
3.3.7
The NCO requires that the
construction noise level to comply with the specified Acceptable Noise Level
(ANL) as given in GW-TM and DA-TM. The ANL is dependent on the Area Sensitivity
Rating for the NSR, as listed in Tables 3.2 and 3.3. For this assessment, it
is anticipated that construction works may be carried for the MTRC Yau Tong
Station such that ANLs are equal to the BNLs - 3.
3.3.8
The ANLs from GW-TM for
Construction other than Percussive Piling are given in Table 3.2 with no correction applied
to allow for noise contribution from construction work associated with more
than one CNP. The Authority should be
approached for clarification of an appropriate correction for multiple permit
situations.
Table 3.2 Acceptable Noise Levels for
Construction other than Percussive Piling, dB(A)
|
Time Period
|
ASR “A”
|
ASR “B”
|
ASR “C”
|
|
All days during the
evening (1900 to 2300 hours), and general holidays (including Sundays) during
the day-time and evening (0700 to 2300 hours)
|
60
|
65
|
70
|
|
All days during the
night-time (2300 to 0700 hours)
|
45
|
50
|
55
|
3.3.9
In addition, other noise
regulations, Noise Control (Hand held percussive breakers) Regulations and
Noise Control (Air Compressors) Regulations govern the noise from hand held
breakers and air compressors on compliance with the relevant noise emission standards
and the fixing of noise emission labels.
3.4
Methodology
Construction Noise Assessment Methodology
3.4.1
The methodology for assessing
the construction noise other than percussive piling is based on GW-TM, as
summarised in the following:-
i) To identify the affected NSRs within the
Study Area;
ii) To determine the Area Sensitivity Rating
(ASR) of NSRs for construction work;
iii) To identify the phasing of construction work
and, locations and required number of the construction plant items;
iv) To obtain the sound power levels in dB(A) of
the construction equipment from the TM;
v) To determine the distance and distance
attenuations (from geometric spreading and other absorption effects where
appropriate), barrier corrections from a notional noise point source and
reflection corrections at the NSR;
vi) To calculate the Corrected Noise Level (CNL)
which will be generated by the construction work at the NSRs;
vii) To correct for multiple site situations; and
viii) To propose direct mitigation measures, if
necessary, to minimise the impact by the construction work in order to comply
with the stipulated noise limits.
3.4.2
Appropriate mitigation measures
have been evaluated and recommended in cases where the stipulated noise
criteria are exceeded at the NSRs. A
systematic approach to the evaluation of the mitigation measures has been
adopted with the following three levels of mitigation :-
·
Level One – use of quiet plant
and construction methods
·
Level Two – erection of
temporary noise screens and barriers
·
Level Three – reduction in
plant items
3.4.3
The use of quiet plant for the
reclamation is encouraged as some models of plant are commercially available
with sound power levels lower than that of the standard types specified in the
GW-TM.
3.4.4
Noise barriers of 3 to 5 m high
site hoarding can be erected at the site boundary with a 5dB(A) reduction
achievable from screening noisy construction activities from the NSRs. Location
of site access should be carefully chosen without significantly compromising
the effectiveness of the site barriers.
Stationary PME including generators and compressors can be fitted with
acoustic enclosures to achieve a noise reduction of 10dB(A) or more. Movable
barriers erected close to a noisy plant are also found to be effective in
reducing noise emission.
3.4.5
The Contractor has to make the
choice of the number and types of construction equipment taking into account
the use of quiet plant while devising a feasible work programme.
3.4.6
The tentative programme for the
whole development has been prepared by MCAL.
3.4.7
The reclamation scheme phasing
and Construction Programme have been prepared by MGS, the specialist consultant
on reclamation construction, to cover construction work tasks to be carried out
within different work areas. The
construction programme is divided into phases as described in the following and
shown in Figure 3.2.
·
Seawall Construction - this
phase of the reclamation will require temporary edge structures or seawalls to
be formed.
·
Phase 1 works will form the
main body of the reclamation. The extent will cover sites 1a to 1d with the
reclamation work progressing from the landside towards the sea.
·
Phase 2 works will take place
above the pipe reserve and will be formed by a piled deck.
3.4.8
Details of the Construction
Programme are given in Appendix 3A. Construction of Seawall
will commence in January 2004 and end in February 2004. Phase 1 works for Main
Reclamation will commence in May 2004 and end in February 2007. Phase 2 works for bored pile will commence in
April 2004 and end in October 2007.
3.4.9
The Schedule of Plant for
reclamation has been provided by the MGS, the specialist consultant on
reclamation construction (Appendix 3B). The types of construction plant that may be
required for the reclamation works, together with the sound power levels
extracted from GW-TM, are given in Table 3.3. These sound power levels are likely to result
in the worst case noise prediction as quiet models of plant are now
commercially available.
Table 3.3 Listing of PME items for
Reclamation Works
|
DA-TM CNP Reference
|
Powered Mechanical Equipment (PME)
|
Maximum SWL
dB(A)
|
|
CNP048
|
Crane, mobile / barge mounted
|
112
|
|
CNP061
|
Derrick barge
|
104
|
|
CNP063
|
Dredger, grab
|
112
|
|
CNP066
|
Dumper
|
106
|
|
CNP067
|
Dump truck
|
117
|
|
CNP081
|
Excavator
|
112
|
|
CNP164
|
Piling, bored, grab & chisel
|
115
|
|
CNP165
|
Piling, bored, oscillator
|
115
|
|
CNP166
|
Piling, bored, reverse circulation drill
|
100
|
|
CNP021
|
Bar bender & cutter
|
90
|
|
CNP044
|
Concrete lorry mixer
|
109
|
|
CNP047
|
Concrete pump
|
109
|
|
CNP170
|
Poker
|
113
|
|
CNP101
|
Generator
|
108
|
|
CNP003
|
Air compressor
|
104
|
|
CNP282
|
Water pump
|
103
|
|
CNP221
|
Tug boat
|
110
|
3.4.10
The notional source position at
each site has been taken in accordance with GW-TM to calculate the noise
contribution from the site. The total noise level due to reclamation works is
obtained by summing up contributions from all sites.
3.4.11
Computer analysis models will
be employed to assess the noise impact, taking into consideration the NSR and
source location, noise barriers, NSR orientation, contribution from various
phases and construction sites.
Noise Assessment of Demolition Works
3.4.12
Demolition works are scheduled
to be carried out for a duration of 2 months starting from July 2005 to August
2005 (Appendix 3A).
3.4.13
The types of PME plant that may
be required for the demolition works, together with the sound power levels, are
given in Table 3.4.
Table 3.4 Listing of PME items for Demolition
Works
|
DA-TM CNP Reference
|
Powered Mechanical Equipment (PME)
|
Maximum SWL dB(A)
|
|
CNP081
|
Excavator
|
112
|
|
CNP023
|
Breaker
|
108
|
|
CNP101
|
Generator
|
108
|
|
CNP003
|
Air compressor
|
104
|
|
CNP067
|
Dump truck
|
117
|
|
CNP021
|
Bar bender & cutter
|
90
|
3.4.14
Demolition works will be
carried out to three main areas with shipyard buildings or structures lying to the
north, east and south of Yau Tong Bay. The notional source position at each site has
been taken in accordance with GW-TM to calculate the contribution from the site
due to the demolition works. The total
noise level is obtained by summing up contributions from all three areas.
Noise Assessment of Vehicular Movement on
Haul Roads
3.4.15
The assessment of noise from
the movement of vehicles on-site shall be based on the methodology recommended
in the British Standard BS 5228 Part I, Noise Control on Construction and Open
Site, 1984 (BS).
3.5
Baseline Conditions and
Noise Sensitive Receivers
Yau Tong Area
3.5.1
The existing NSRs have been
located through site visits. For planned developments, representative NSRs have
been identified by reference to Outline Zoning Plan and, information from MTRC,
Housing Department and Planning Department.
3.5.2
The major residential
developments in the Yau Tong area are Yau Tong Centre, Yau Tong Estate and East
Harbour Crossing (EHC) site. The Yau
Tong Estate is being redeveloped to have residential blocks and two new schools
to replace the two existing schools, namely, Po Chiu College and St. Antonius
Primary School. These new schools have
started operation in September 1999 and they are located close to the Yau Tong
MTR Station. Noise mitigation measures with upgraded glazing and
air-conditioners have been provided to these schools for reducing noise impacts
from the Station Construction (Appendix 3C).
3.5.3
Located to the northwest of the
site are a few 1- to 2-storey village houses of Cha Kwo Ling.
3.5.4
The other buildings in the Yau
Tong area are industrial buildings, located south of Ko Fai Road and along Cha Kwo Ling Road. As industrial buildings are not considered as
NSRs, the noise impacts from the reclamation construction works do not need to
cover these industrial buildings.
3.5.5
In addition, the other major
housing development and three new schools at EHC Site located to the north and
north-west of Yau Tong Estate are scheduled to complete construction in
September 2004 for EHC Phases 1, February 2005 for EHC Phase 2 and in September
2004 for the schools, (Appendix 3D). Noise mitigation measures are expected to be
provided by the Government to protect the schools from the significant traffic
noise impact from heavily trafficked Cha Kwo Ling Road and that the development
will make provision to provide the required noise mitigation measures if
necessary.
Ambient Noise Condition
3.5.6
The existing ambient noise climate
of the representative NSRs is dominated by traffic noise from Cha Kwo Ling
Road, Ko Fai Road and Lei Yue Mun Road, the distant Eastern Harbour Crossing
and local roads. The industrial noise
also contributes to the overall ambient noise levels in the Yau Tong area.
Representative NSRs
3.5.7
The NSRs (planned and existing)
closest to the reclamation have been identified as representative NSRs and are
shown in Table 3.5 and Figure 3.3. The information on the completion year of each NSRs is extracted
from the letter prepared by Hong Kong Housing Authority (Appendix 3D).
3.5.8
For the Yau Tong Estate and Yau
Tong Centre, the NSRs are assumed to have open windows and a direct line of
sight to the appropriate construction site. Inspection conducted in Dec 98 has
confirmed that the Cha Kwo Ling school was no longer in use. For the Cha Kwo
Ling village houses closest to site, the topography and existing screening
available from the ventilation shaft structure and industrial buildings along
Cha Kwo Ling Road provide noise screening to the majority of the construction
sites. Hence, the NSRs are assumed to have a direct line of sight to the
construction site (Site 1a) but to have a 10dB(A) barrier effect for the other
construction sites screened from sight.
3.5.9
Yau Tong Estate Phases 3 and 5,
which have completion year later than Phases 1 and 2, will be screened by
Phases 1 and 2 so that the occupants will not be adversely affected by the
construction noise.
3.5.10
The phasing of reclamation work
makes it practical to divide the reclamation area into smaller construction
sites, as advised by MGS, the specialist consultant on reclamation
construction. For each site, the
Notional Source Position (NSP) has been determined in accordance with the
guidelines given in DA-TM.
Table 3.5 Noise Sensitive Receivers closest
to reclamation site
|
|
|
|
Distance to
Worksite (m)
|
|
NSRs
|
Representative
NSRs
|
Completion Year
|
Seawall
Construction
|
1a
|
1b
|
1c
|
1d
|
2
|
|
RYTE1
|
Yau Tong Estate (Phase 1)
|
08/2000
|
830
|
714
|
245
|
420
|
570
|
690
|
|
RYTE2
|
Yau Tong Estate (Phase 2)
|
10/2001
|
850
|
740
|
245
|
415
|
580
|
610
|
|
RYCT
|
Yau Tong Centre
|
existing
|
759
|
759
|
371
|
470
|
576
|
746
|
|
RCKL
|
Cha Kwo Ling
|
existing
|
405
|
405
|
539
|
397
|
422
|
321
|
|
REHC1
|
East Harbour Crossing Housing Estates (Phase 1)
|
09/2004
|
825
|
700
|
255
|
400
|
560
|
525
|
|
REHC2
|
East Harbour Crossing Housing Estates (Phase 2)
|
02/2005
|
660
|
540
|
195
|
365
|
405
|
345
|
|
RSCH1
|
New School 1 at YTE (North)
|
09/1999
|
870
|
745
|
270
|
435
|
600
|
600
|
|
RSCH2
|
New School 2 at YTE (South)
|
09/1999
|
840
|
745
|
245
|
415
|
585
|
615
|
|
RSCH3
|
New Schools at EHC
|
09/2004
|
615
|
495
|
105
|
190
|
350
|
320
|
3.6
Prediction of Construction
Noise Impacts
Prediction of noise due to Reclamation
3.6.1
The construction noise levels are
predicted at the representative NSRs using the methodology described in Section 3.4, the sound power levels of plant items listed in Table 3.3 and the reclamation programme
and anticipated plant schedule given in Appendices 3A and 3B.
Construction Noise affecting Domestic
Premises
3.6.2
The results of the noise
prediction for domestic premises are presented in Figures 3.4a – 3.4f and Appendix 3E. The predicted facade
noise levels are within the 75dB(A) criterion for domestic premises over the
whole period of reclamation.
Construction Noise affecting Schools
3.6.3
The noise prediction results
for schools are presented in Figures 3.4g – 3.4i and Appendix 3E. The predicted noise levels exceed the 70dB(A) criterion for
schools and the 65dB(A) criterion during school examinations during Jan 2005
and Jul 2005 to Sep 2005.
3.6.4
Noise mitigation measures as
described in Section 3.7 should be adopted to mitigate the noise impact due to the
reclamation works.
Prediction of noise due to Demolition
Works
3.6.5
The plant noise levels due to
the demolition works on the existing boatyard/ industrial buildings are in the
range of 58 - 76dB(A) at the NSRs (Table 3.6). Details of calculations are given in Appendix 3F. The noise prediction
results at the NSRs are also presented in Figures 3.4a to 3.4i.
Table 3.6 Predicted Noise Levels in dB(A) Leq due to demolition
works at NSR locations
NSR locations
|
Predicted Noise Levels, dB(A) Leq *
|
Noise Criteria dB(A)
|
Compliance
|
|
RYTE1
|
71
|
75
|
Yes
|
|
RYTE2
|
71
|
75
|
Yes
|
|
RYCT
|
58
|
75
|
Yes
|
|
RCKL
|
58
|
75
|
Yes
|
|
REHC1
|
68
|
75
|
Yes
|
|
REHC2
|
72
|
75
|
Yes
|
|
RSCH1
|
69
|
65/70
|
No/Yes
|
|
RSCH2
|
72
|
65/70
|
No/No
|
|
RSCH3
|
76
|
65/70
|
No/No
|
* Note : Predicted noise levels include facade
effect but exclude contributions from background.
3.6.6
The predicted noise levels at
the residential NSRs are well within the stipulated limit as stated in Section 3.3. However, the predicted
noise levels at the schools exceed the noise criteria. Noise mitigation
measures as described in Section 3.7 should be adopted to mitigate
the noise impact due to the demolition works.
Prediction of noise due to vehicular
movement on haul roads
3.6.7
According to MGS, the
anticipated heavy vehicle/ PME movement on haul roads will be about a vehicle
every 2 to 5 minutes in and out of the site, i.e. an additional traffic flow of
30 vehicles per hour. This flow is insignificant as compared to the 2,450 -
3,700 vehicles per hour on Cha Kwo Ling Road and 850 - 1650 vehicles on
Ko Fai Road.
3.6.8
As the exact routes for access
roads in and around the sites are not available, the access roads are assumed
to cover all the boundaries of each reclamation areas so as to be conservative
in the noise prediction.
3.6.9
The predicted noise levels at
the NSRs due to movement of heavy vehicles / PME items within the reclamation
sites are shown in Table 3.7. Calculations of the noise prediction are
given in Appendix 3G.
Table
3.7 Predicted
Noise Levels in dB(A) Leq due to vehicular movement on haul roads at
NSR locations
NSR locations
|
Predicted Noise Levels, dB(A) Leq *
|
|
RYTE1 (Yau Tong Estate,
Phase 1)
|
49
|
|
RYTE2 (Yau Tong Estate,
Phase 2)
|
49
|
|
RYCT (Yau Tong Centre)
|
38
|
|
RCKL (Village at Cha Kwo
Ling)
|
43
|
|
REHC1 (EHC Phase 1)
|
49
|
|
REHC2 (EHC Phase 2)
|
51
|
|
RSCH1 (School at north of
YTE)
|
49
|
|
RSCH2 (School at south of
YTE)
|
49
|
|
RSCH3 (3 Schools at EHC
site)
|
53
|
* Note : Predicted noise levels include facade
effect but exclude contributions from background.
3.6.10
The predicted noise levels at
all of the NSRs are well within the stipulated limit as stated in Section 3.3. As compared with the PME noise levels, the
predicted levels due to vehicular movement on haul roads are insignificant as
these are lower than the predicted PME noise by about 20 dB(A).
3.6.11
The background noise levels
measured at the NSRs due to road traffic and industrial activities were in the
range of 68 - 75dB(A). The predicted
levels due to vehicular movement on haul roads are insignificant and,
therefore, the haul road movement is unlikely to cause any noise nuisance to
the NSRs.
3.7
Mitigation Measures for Construction
Noise
3.7.1
The predicted daytime
construction noise levels exceed the criteria stipulated in the EIA-TM for
schools during January 2005 and July 2005 to September 2005. The following
mitigation measures are recommended to reduce further the construction noise
impact:-
·
Scheduling of work
·
Siting of facilities
·
Reduction of operating time
·
Use of Quiet Powered Mechanical
Equipment (PME)
·
Use of temporary noise barriers
·
Use of movable noise barriers
·
Adopt good site practice
Scheduling of Work
3.7.2
The Contractor has to make the
choice of the number and types of construction equipment taking into account
the use of quiet plant while devising a feasible work programme.
3.7.3
This includes minimizing noisy
operations during examination periods; avoiding simultaneous operation of noisy
equipment; retaining existing features that can act as a noise barrier until
the last phase; and erecting, as early as possible, any new structures which
will have the effect of screening noise sources. Such screens can reduce noise levels by
15dB(A) or more.
Siting of Facilities
3.7.4
Noisy equipment, such as
emergency generators and water pumps, should always be sited as far as possible
from noise sensitive receivers.
Consideration should also be given to the use of structures such as site
offices and stores as noise barriers.
Reduction of Plant Operating Time
3.7.5
The activity sound power levels
could be reduced by limiting the plant operating time. For a 30-minute noise exposure time specified
for the noise criteria, reducing the total operating time to 70% (i.e. 21
minutes) would result in a 1.5dB(A) reduction of the noise exposure. The operating time of breakers is recommended
to be reduced to 70% during the demolition works.
Use of Quiet Powered Mechanical Equipment
(PME)
3.7.6
The contractor should be
requested to use quiet PME during reclamation and demolition works, whose
actual SWL is less than the value specified in GW-TM. This is one of the most effective measures
and is increasingly practicable because of the availability of quiet
equipment. Examples of SWLs for specific
silenced PME are given in the following Table 3.8.
Table 3.8 Listing of Quiet PME items
Powered Mechanical Equipment (PME)
|
Reference
(GW-TM and BS)
|
Maximum SWL, dB(A)
|
|
Crane, mobile
|
BS Table C.7, 110
|
106
|
|
Dumper
|
BS Table C.7, 81
|
96
|
|
Dump truck
|
BS Table C.9, 19
|
102
|
|
Excavator
|
BS Table C.6, 28
|
102
|
|
Truck mixer
|
BS Table C.6, 23
|
100
|
|
Concrete pump
|
BS Table C.6, 36
|
106
|
|
Generator
|
TM CNP103
|
95
|
|
Air compressor
|
TM CNP001
|
100
|
Use of Temporary Noise
Barriers
3.7.7
It is recommended to erect a
noise barrier of 3m to 5m high along the site boundary adjoining Cha Kwo Ling Road and Ko Fai Road during the construction
phase. The noise barrier should be
constructed of impervious material with minimum 15kg/m2 surface
density. The noise barrier would provide
screening losses of 3 to 5 dB(A) and reduce the construction
noise impact on the NSRs. Location of
site access should be carefully chosen without significantly compromising the
effectiveness of the site barriers.
Use of Movable Noise Barriers
3.7.8
Movable noise barriers can be
very effective at screening NSRs from noisy plant. A 8m high movable barrier with skid footing
and a small cantilevered upper portion can be located within a few metres of
static plant and within about 5m of mobile plant. It is estimated that movable noise barriers
of this type can produce 10dB(A) of screening for static plant and 5dB(A) for
mobile plant. Movable noise barriers are
recommended in this study for grab & chisel bored piling and oscillator
bored piling since Jan 2005 which can provide 10dB(A) of screening benefits to
the NSRs.
Adopt Good site practice
3.7.9
Good site practice and noise
management can considerably reduce the impact of the construction sites’
activities on nearby NSRs. The following
measures should be followed during each phase of construction:
·
only well-maintained plant
should be operated on-site and plant should be serviced regularly during the
construction programme;
·
machines and plant (such as
trucks) that may be in intermittent use should be shut down between work periods
or should be throttled down to a minimum;
·
plant known to emit noise
strongly in one direction, should, where possible, be orientated so that the
noise is directed away from nearby NSRs;
·
silencers or mufflers on
construction equipment should be utilised and should be properly maintained
during the construction period;
·
mobile plant should be sited as
far away from NSRs as possible; and
·
material stackpiles and other
structures should be effectively utilised, where practicable, to screen noise
from on-site construction activities.
3.8
Evaluation of Residual
Impacts
Reclamation
3.8.1
With the implementation of
quiet plants and movable noise barriers for grab and chisel bored piling and
oscillator bored piling, the noise levels at the NSRs were predicted. Details
of predicted noise levels are given in Appendix 3H.
Demolition Works
3.8.2
With the implementation of
quiet plants and reduction of operating time for breakers, the noise levels at
the NSRs were predicted. The results are summarised in the following Table 3.9. Details of calculation are given in Appendix 3I.
Table 3.9 Predicted Noise Levels in dB(A) Leq
due to demolition works at NSR locations
NSR Locations
|
Predicted Noise Levels, dB(A) Leq *
|
Noise Criteria dB(A)
|
Compliance
|
|
RYTE1
|
63
|
75
|
Yes
|
|
RYTE2
|
63
|
75
|
Yes
|
|
RYCT
|
49
|
75
|
Yes
|
|
RCKL
|
50
|
75
|
Yes
|
|
REHC1
|
60
|
75
|
Yes
|
|
REHC2
|
64
|
75
|
Yes
|
|
RSCH1
|
61
|
65/70
|
Yes/Yes
|
|
RSCH2
|
64
|
65/70
|
Yes/Yes
|
|
RSCH3
|
68
|
65/70
|
No/Yes
|
3.8.3
The predicted noise levels due
to the reclamation and demolition works are presented in Figures 3.5a to 3.5i. Results indicate that the mitigated noise
levels at RSCH1 and RSCH2 comply with the 65dB(A) noise criterion over the
whole period of reclamation.
3.8.4
RSCH3 will have cumulative
noise levels up to 70dB(A) for a short period due to the demolition works
during the summer vocation period from July 2005 to August 2005. The cumulative noise level during September
2005 is 66dB(A), which is well within the 70dB(A) criterion for normal school
days. As no examination will be held
during September, there is no residual noise impact at RSCH3.
3.9
Cumulative Impacts
3.9.1
During the construction period
of the reclamation works, other concurrent construction activities will be
carried out in the vicinity, such as, for the Yau Tong Bay Development (Package
2), Yau Tong Estate Development and the East Harbour Crossing Housing
Estates. The cumulative construction
noise impacts at the NSRs from the overall construction works in Yau Tong area
are presented in the following.
3.9.2
The possibility of a tunnel
alignment option for the proposed Western Coast Road (WCR) project was made
known to the public in March 2000, given the strong public objections on the
coastal alignment. Since the alignment
has not been finalised at the time of preparing this report, the construction
of WCR is likely not to be started and overlapped with the programme of the
reclamation.
Yau Tong Bay Development (Package 2)
3.9.3
The construction programme for
the foundation/superstructure works at the Yau Tong Bay Development is
scheduled from October 2005 to September 2015, which will overlap with the
construction period of reclamation works for approximately two years.
3.9.4
With reference to the EIA Report
titled “Yau Tong Bay Development – Engineering Feasibility Study for the
Comprehensive Development at Yau Tong Bay”, the mitigated
construction noise levels at all NSRs due to the foundation/superstructure
works are in the range of 58 - 69 dB(A), which comply with the stipulated noise
criteria. The predicted noise levels are summarised in the following Table 3.10.
Table 3.10 Predicted Construction Noise levels
at NSRs due to the foundation/ superstructure works of Yau Tong Bay Development (Package 2)
|
|
Distance to
Notional Source
|
Predicted
Mitigated CNLs (dB(A))
|
Criteria
|
|
Representative NSRs
|
Position (m)
|
Foundation
|
Superstructure
|
(dB(A))
|
|
RYTE1
|
180
|
67
|
67
|
75
|
|
RYTE2
|
216
|
65
|
65
|
75
|
|
RYCT
|
300
|
52
|
52
|
75
|
|
RCKL
|
236
|
60
|
60
|
75
|
|
REHC1
|
228
|
65
|
65
|
75
|
|
REHC2
|
156
|
68
|
68
|
75
|
|
RSCH1
|
276
|
58
|
58
|
65/70
|
|
RSCH2
|
190
|
61
|
61
|
65/70
|
|
RSCH3
|
76
|
69
|
69
|
65/70
|
3.9.1
The cumulative impacts at the
NSRs due to the overlap period of the Yau Tong Bay reclamation works and
construction works for the Yau Tong Bay Development are presented in Figures 3.6a to 3.6i. Results indicate that the cumulative noise
levels at all of the residential NSRs and RSCH 1 and 2 comply with the
construction noise criteria for domestic premises and school during examination
over the whole period of reclamation.
3.9.2
RSCH3 will have cumulative
noise levels greater than 65dB(A) after July 2005 and the start of construction
of Package 2. Since the predicted noise
levels are within the 70dB(A) criterion for normal school days and noise
mitigation measures in the form of upgraded glazing and air-conditioner units
are expected to be provided to RSCH3 (Section 3.5.5), the roomside noise levels of the school are considered as
acceptable.
Other Developments in Yau Tong Area
3.9.3
There are a number of planned
and committed housing developments in Yau Tong Area, including Yau Tong Estate
Development and East Harbour Crossing Housing Estates. The completion years for the developments are
given in Appendix 3D.
3.9.4
Noise levels have been
predicted at the NSRs based on a sound power level of 121dB(A) for the
construction activities at each development. The cumulative construction noise
impacts caused by the reclamation of Yau Tong Bay, the construction of Yau
Tong Bay Development and the construction of nearby developments are shown in Figures 3.7a – 3.7i and summarised in Appendix 3J. Results indicate that the predominant noise
impact will be caused by the construction activities at the other developments
rather than due to the reclamation of Yau Tong Bay.
3.10
Environmental Monitoring
and Audit Requirements
3.10.1
The Environmental Monitoring
and Audit (EM&A) programme should include the following:
i)
the collection of noise data;
ii)
the organization and
interpretation of the environmental monitoring data to establish a record of
change associated with the implementation of the project;
iii)
the verification that the noise
levels measured by an environmental monitoring programme in compliance with the
regulatory requirements, standards and established environmental quality
performance limits;
iv)
the comparison of project
impact predictions with actual impacts for the purpose of assessing the
accuracy of predictions at the NSRs;
v)
the assessment of the
effectiveness of the environmental management systems, practices and
procedures;
vi)
event and action plans shall be
included and linked to the environmental quality performance. The determination of the degree and scope of
any necessary remedial measures in case of exceedance of compliance, for which
environmental monitoring forms the basis, or the recommendation of
environmental controls and operations in the event that the organisation’s
environmental objectives are not achieved.
3.10.2
The EM&A Manual will
provide a description of the organisational arrangements for the EM&A
programme and will stipulate the details of the construction monitoring
required and actions to be taken in the event of exceedances.
3.11
Conclusion
3.11.1
An environmental noise impact
assessment on the proposed Yau Tong Bay Development Reclamation has been
conducted to predict the future construction noise impacts at the noise
sensitive receivers in the Yau Tong neighbourhood.
3.11.2
With the proposed use of quiet
plants, reduction of plant operating time and use of movable noise barriers for
the reclamation and demolition works, the nearby NSRs will not be adversely
affected.
3.11.3
The cumulative assessment
indicate that the predominant noise impact will be caused by the construction
activities at the other developments rather than due to the reclamation of Yau Tong Bay.
3.12
References
[1]
Noise Control Ordinance (NCO).
[2]
Environmental Protection
Department "Technical memorandum on EIA Process", Sep 1997 (EIA-TM).
[3]
Environmental Protection
Department "Technical memorandum on noise from construction work other
percussive piling", July 1991 (GW-TM).
[4]
Environmental Protection
Department "Technical memorandum on noise from construction work in
designated areas", March 1996 (DA-TM).
[5]
Environmental Protection
Department "Technical memorandum on noise from percussive piling",
June 1997 (PP-TM).
