Tuen Mun Chek Lap Kok Link – Southern Connection Viaduct Section

 

Acoustic Decoupling Measures Plan

Rev. No.          : A

Effective Date : 27 Sep 2013

J3518

 

 

REVISION STATUS SHEET

 

Rev. No.

Effective Date

Summary of Revision

Prepared

Approved

-

23 Sep 2013

First Submission

Roy Leung

Andrew Veness

A

27 Sep 2013

Table 1, Table 2 & App B

Roy Leung

Andrew Veness

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

CONTENTS

1......... INTRODUCTION.. 1

1.1         Project Descriptions. 1

2......... PURPOSE OF THE PLAN.. 1

3......... MARINE CONSTRUCTION NOISE SOURCES.. 1

3.1         Bored Piling Work. 1

3.2         Working Vessels and Platforms. 1

4......... ACOUSTIC DECOUPLING MEASURES.. 2

4.1         Working Vessels and Platforms – Isolation Pad. 2

4.2         General Notes to Install the Measures. 3

 

 

 

APPENDICES

 

Appendix A          Site Layout Plan

Appendix B          Samples of Stationary PMEs on Working Vessels

Appendix C          Proposed Isolation Pad Details – PO MAT

Appendix D          Proposed Isolation Pad Details – K-FLEX ST

Appendix E          Proposed Isolation Pad Details – Kinetics ISOlayment QT-B

 

 

 

     


1             INTRODUCTION

 

1.1         Project Descriptions

 

Gammon Construction Limited (GCL) has been commissioned to design and construct the Contract No. HY/2012/07 – Tuen Mun Chek Lap Kok Link – 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 Cheung Tung Road at North Lantau, and associated works.

 

2             PURPOSE OF THE PLAN

 

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 – Tuen Mun Chek Lap Kok Link – 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.

 

3             MARINE CONSTRUCTION NOISE SOURCES

 

3.1         Bored Piling Work

 

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.

 

3.2         Working Vessels and Platforms

 

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.

 

4             ACOUSTIC DECOUPLING MEASURES

 

4.1         Working Vessels and Platforms – Isolation Pad

 

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.

 

 

 

 

 

4.2         General Notes to Install the Measures

 

·       To forbid direct vibration transmission, adequate plinth clearance shall be kept all around.

·       Close all panels or doors of generators when in use.

·       To avoid noise breakout and the undesirable sound paths through gaps, the foundation where the equipment to be placed shall be flat and level.

·       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

 

 


 

Description: Generator

Type A – Generator on vessel board

 

Description: Air compressor 3

Type B – Air compressors on vessel board

 


 

 

 

 

APPENDIX C

 

Proposed Isolation Pad Details –

PO MAT

 

 


Description: Appendix B_Page_01

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Description: Appendix B_Page_13


 

 

APPENDIX D

 

Proposed Isolation Pad Details –

K-FLEX ST

 


 


 

 

APPENDIX E

 

Proposed Isolation Pad Details –

Kinetics ISOlayment QT-B