|
Tuen Mun
Chek Lap Kok Link ¡V
Southern Connection Viaduct Section Acoustic Decoupling Measures Plan |
Rev.
No. :
A |
Effective
Date : 27 Sep 2013 |
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J3518 |
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CONTENTS
2......... PURPOSE OF THE PLAN
3......... MARINE CONSTRUCTION NOISE SOURCES
3.2 Working Vessels and Platforms
4......... ACOUSTIC DECOUPLING MEASURES
4.1 Working Vessels and Platforms ¡V Isolation Pad
4.2 General Notes to Install the Measures
APPENDICES
Appendix A Site
Layout Plan
Appendix B Samples of Stationary PMEs on Working Vessels
Appendix C Proposed Isolation Pad Details ¡V
Appendix D Proposed Isolation Pad Details ¡V K-
Appendix E Proposed
Isolation Pad Details ¡V Kinetics ISOlayment QT-B
Gammon Construction Limited (GCL) has been commissioned
to design and construct the Contract No. HY/2012/07 ¡V Tuen
Mun Chek Lap Kok Link ¡V Southern Connection Viaduct Section for the
Highways Department (HyD) of the Government of the
Hong Kong Special Administrative Region (HKSARG). The Works to be executed comprise the
construction of a dual 2-lane elevated carriageway between the HZMB HKBCF and
North Lantau Highway (NLH) with associated slip
roads, as well as modifications and realignment of sections of the NLH and
The Acoustic Decoupling Measures
Plan (ADMP) has been developed in accordance with Condition 2.5 of the
Environmental Permit (EP-354/2009/A) for the Highways Department Contract
namely Contract No. HY/2012/07 ¡V Tuen
Mun Chek Lap Kok Link ¡V Southern Connection Viaduct Section.
The ADMP shall describe the measures to be taken to minimize impacts to
marine ecological environment when carrying out bored piling, dredging and
reclamation works.
The location of the Contract is illustrates in Appendix A.
Bored piling, instead of percussive piling, will be undertaken with
permanent steel casing for construction of the substructures of piers.
Low-vibration hammers will be used to install the casings into the seabed
following the alignment control guides set on the platform.
In order to minimize impacts to Chinese White Dolphin (CWD) by bored
piling, dolphin exclusion zone of 250m around the work area will be implemented
and monitored by independent dolphin observers. Dolphin observers shall scan
the exclusion zone at least 30 minutes before start of bored piling works, to
ensure CWD not being disturbed.
According to Section 8.11.9.29 of the approved EIA Report, the expected
acoustic disturbance from large vessels is well below the primary acoustic
range for CWD which in general show the increased use of high-frequency sound.
As such, main engines of the proposed working vessels are not considered
to be a significant source of acoustic disturbance to CWD. However, there is
still a small possibility that noise would be transmitted from the onboard
equipment (e.g. air compressor) into the sea (Section 8.14.4.13 of the approved
EIA Report). Therefore, acoustic decoupling measures for noisy equipment which
are not embedded on vessels are required to minimise the possible noise impact
on marine ecology.
Stationary powered mechanical equipments mounted on boards of working
vessels or platforms, when operating, may generate vibration or noise through
the hull if they are directly placed on the deck without proper isolation.
These common equipments on board are summarized in Table 1:
Table 1 Summary
of Noisy Equipment Identified on Working Vessels
Working
Vessel |
Noisy
Equipment identified on Working Vessel |
Derrick Lighter |
Generator (Diesel, 35.81kW, 1.5 Tons approx.) |
Jack-Up
Platform |
Generator (Diesel, 44.76kW, 3 Tons approx.) Generator (Diesel, 4.48kW, 1 Ton approx.) |
Flat
Top Barge |
Generator (Diesel, 4.47kW, 1 Ton approx.) Generator (Diesel, 80.57kW, 5 Tons approx.) Air compressor (Diesel, 7bar, 1 Ton approx.) |
Hopper
Barge |
No noisy equipment will be provided onboard. |
Crane
Barge |
No noisy equipment will be provided onboard. |
In order to minimize the noise transmission to the sea, acoustic
decoupling measures for the stationary equipment mounted on boards will be
adopted. Sample
of stationary powered mechanical equipments on working vessels is
illustrated in Appendix
B.
Noise isolation pad is proposed to separate the stationary equipments
from the decks or hulls in order to reduce noise transmission to the sea via
the working vessels or platforms.
Instead of directly mount on decks, noisy equipments will be fixed on
noise isolation pad. Prior to installation, GCL will ensure the foundation of
equipments is flat and level. Adequate clearance all around the noisy equipment
will be kept to avoid direct vibration transmission to other materials and
machineries. The dimensions of the proposed isolation
pad for the identified noisy equipments are listed in Table 2.
Table 2 Summary
of Noisy Equipment Identified on Working Vessel
Proposed
Working Vessel |
Noisy
Equipment identified on Working Vessel |
Dimensions
of the Proposed Isolation Pad (L x W x H) |
Derrick
Lighter |
Generator (Diesel, 35.81kW, 1.5 Tons approx.) |
2m x 1m x 30mm approx. |
Jack-Up
Platform |
Generator (Diesel, 44.76kW, 3 Tons approx.) Generator (Diesel, 4.48kW, 1 Ton approx.) |
2m x 1.3m x 30mm approx. 1.5m x 1m x 30mm approx. |
Flat
Top Barge |
Generator (Diesel, 4.47kW, 1 Ton approx.) Generator (Diesel, 80.57kW, 5 Tons approx.) Air compressor (Diesel, 7bar, 1 Ton approx.) |
1.5m x 1m x 30mm approx. 3m x 1.5m x30mm approx. 1.5m x 3m x 30mm approx. |
Three type materials of isolation pad are proposed to be used for noisy
equipments identified on working vessel, the details
are given in Appendix
C, Appendix D and Appendix E.
¡P To
forbid direct vibration transmission, adequate plinth clearance shall be kept
all around.
¡P Close
all panels or doors of generators when in use.
¡P To
avoid noise breakout and the undesirable sound paths through gaps, the
foundation where the equipment to be placed shall be flat and level.
¡P
To further eliminated the sound generation from
noisy parts, flexible bellows silencers, mufflers shall be applied when
necessary.
APPENDIX A Site Location Plan |
APPENDIX B Samples of Stationary PMEs on Working Vessels |
|
Type A ¡V
Generator on vessel board |
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Type B ¡V Air
compressors on vessel board |
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|
APPENDIX C Proposed Isolation Pad Details ¡V |
APPENDIX D Proposed
Isolation Pad Details ¡V |
APPENDIX E Proposed
Isolation Pad Details ¡V Kinetics
ISOlayment QT-B |