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Contract No. HY/2011/03

Hong Kong-Zhuhai-Macao Bridge Hong Kong Link Road

Section between Scenic Hill and Hong Kong Boundary Crossing Facilities

 

 

 

 

 

 

Acoustic Decoupling Measures Plan

 

12 September 2012

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Main Contractor                                                                                                                     Designer

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Contents

1                             Introduction. 1

1.2                          Purpose of the Plan. 1

2                             Acoustic Decoupling Measures Plan. 1

2.1                          Marine Construction Noise Sources. 1

2.2                          Proposed Acoustic Decoupling Measures. 2

 

Appendices

 

Appendix A:     Photos of Proposed Working Vessel

Appendix B:      Proposed Isolation Pad Details

 

Drawings

 

Drawing 4809-RC-2001                    Reclamation Plan (Sheet 1 of 2)

Drawing 4809-RC-2002                    Reclamation Plan (Sheet 2 of 2)



1.1.1       The HZMB Hong Kong Link Road (HKLR) serves to connect the Hong Kong-Zhuhai-Macao Bridge (HZMB) Main Bridge at the Hong Kong Special Administrative Region (HKSAR) Boundary and the HZMB Hong Kong Boundary Crossing Facilities (HKBCF) located at the north eastern waters of the Hong Kong International Airport (HKIA).

1.1.2       China State Construction Engineering (Hong Kong) Ltd. was awarded by Highways Department as the Contractor to undertake the construction works of Contract No. HY/2011/03 Hong Kong-Zhuhai-Macao Bridge Hong Kong Link Road – Section between Scenic Hill and Hong Kong Boundary Facilities (“the Contract”) for the Highways Department of HKSAR.

1.1.3       This Acoustic Decoupling Measures Plan is prepared for Contract No. HY/2011/03 detailing the acoustic decoupling measures plan for the works as part of the plan on marine ecological mitigation measures. 

1.2.1       This Acoustic Decoupling Measures Plan was prepared to fulfill Clause 2.6 of EP-352/2009/A, which states:

The Permit Holder shall deposit with the Director, at least one month before the commencement of construction of the Project, three hard copies and one electronic copy of the design and implementation of acoustic decoupling measures applied during bored piling, dredging and reclamation works.

2.1.1      According to the reclamation design, dredging and bored piling will not be undertaken for this contract.  Non-dredged method for reclamation shall be adopted to avoid dredging and disposal of marine sediments, which will in turn avoid adverse environmental impact to the surrounding.  Ground improvement measures including installation of prefabricated vertical band drains and stone columns are proposed to improve the compressibility and shear strength of the underlying soft soils, in order to meet the contract requirements.  The reclamation plans are attached as Drawings 4809-RC-2001 and 4809-RC-2002.

2.1.2       The marine construction works of the Contract will mainly comprise of the following activities:

·       Marine ground investigation;

·       Installation of silt curtain;

·       Laying geotextile;

·       Filling for stone platform; and

·       Sand filling for reclamation.

2.1.3       According to Section 10.6.4.61 of the approved EIA Report, dolphins mainly use high-frequency sounds that are well above the frequencies produced by most large vessels used in shipping and marine construction activities. Based on available experience in Hong Kong SAR, these types of vessels are not considered to be a significant source of acoustic disturbance.  Main engines of the proposed working vessels are therefore not considered to be a significant source of acoustic disturbance and will not be considered as source of noise and vibration.  However, there is still a small possibility that noise would be transmitted from the onboard equipment (e.g. air compressor) into the sea (Section 10.6.4.62 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.

2.1.4       There will be eight working vessels for the Contract.  They will be used for the construction activities listed in Section 2.1.2.  No air compressors will be provided on broad.  Noisy equipment to be provided on the working vessels have been identified and listed in Table 1.  The photos of the working vessels are shown in Appendix A.

Table 1               Summary of Noisy Equipment Identified on Working Vessels

Working Vessel

Noisy Equipment identified on Working Vessel

Grab Dredger

·            Generator (Diesel, 35.81kW, 1.5 Tons approx.)

Pelican Barge

·            Generator (Diesel, 35.81kW, 1.5 Tons approx.)

Derrick Lighter

·            Winch Generator (Diesel, 80.57kW, 12 Tons approx.)

·            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.)

Crane Barge
(Ocean Channel)

No noisy equipment will be provided onboard. 

Crane Barge
(Chung Kong)

No noisy equipment will be provided onboard. 

Flat Top Work Barge

No noisy equipment will be provided onboard. 

 

2.1.5       Noise from these identified generators may be transmitted to the sea through the hull if they are directly placed on the deck without proper isolation.  In order to minimize the noise transmission to the sea, acoustic decoupling measures for generators are proposed. 

2.2           Proposed Acoustic Decoupling Measures

2.2.1       Noise isolation pad is proposed to separate the generators from the deck or hull in order to reduce noise transmission to the sea via the vessel.  The proposed isolation pad details are given in Appendix B.

2.3           Implementation of Acoustic Decoupling Measures

2.3.1       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)

Grab Dredger

·  Generator (Diesel, 35.81kW, 1.5 Tons approx.)

·  2m x 1m x 30mm approx.

Pelican Barge

·  Generator (Diesel, 35.81kW, 1.5 Tons approx.)

·  2m x 1m x 30mm approx.

Derrick Lighter

 

·  Winch Generator (Diesel, 80.57kW, 12 Tons approx.)

·  Generator (Diesel, 35.81kW, 1.5 Tons approx.)

·  6m x 3m x 30mm 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.)

·  1.5m x 1m x 30mm approx.

·  3m x 1.5m x30mm approx.

 

2.3.2       Instead of directly mount on the deck, the generator will be fixed on noise isolation pad. Prior to installation, the Contractor will ensure the foundation of equipment is flat and level.  Adequate clearance all around the noisy equipment will be kept to avoid direct vibration transmission to other materials and machineries. 

 


Appendix a

Photos of the Proposed Working Vessels
Appendix A – Photo of Proposed Working Vessels

 

Proposed Working Vessel

Photo

Grab Dredger

Pelican Barge

Derrick Lighter

Jack-Up Platform

Flat Top Barge

Crane Barge

(Ocean Channel)

Crane Barge

(Chung Kong)

Flat Top Work Barge

 

Appendix B

Proposed Isolation Pad Details