Drainage Improvement in Big Wave Bay
Project Profile
Prepared by : Drainage Services Department
July 2010
Drainage Improvement in Big Wave Bay Project Profile Drainage Services Department ______
TABLE OF CONTENTS
1. PROJECT INFORMATION ...... 1 1.1 Project Title ...... 1 1.2 Purpose and Nature of Project ...... 1 1.3 Name of Project Proponent ...... 1 1.4 Location and Scale of Project ...... 1 1.5 Number and Types of Designated Project to be Covered by this Project Profile ...... 1 1.6 Name and Telephone Number of Contact Person ...... 1 2. OUTLINE OF PLANNING AND IMPLEMENTATION PROGRAMME ...... 2 2.1 Planning and Implementation of the Proposed Project ...... 2 2.2 Project Timetable ...... 2 2.3 Site Activities Involved ...... 2 3. MAJOR ELEMENTS OF THE SURROUNDING ENVIRONMENT...... 2 3.1 Noise ...... 2 3.2 Air ...... 2 3.3 Ecology ...... 2 3.4 Cultural Heritage ...... 3 4. POSSIBLE IMPACTS ON THE ENVIRONMENT ...... 3 4.1 Noise ...... 3 4.2 Air and Dust ...... 3 4.3 Water ...... 4 4.4 Solid Waste ...... 4 4.5 Ecology ...... 4 4.6 Cultural Heritage ...... 5 4.7 Landscape and Visual ...... 5 4.8 Others ...... 5 5. ENVIRONMENTAL PROTECTION MEASURES TO BE INCORPORATED IN THE DESIGN AND ANY FURTHER ENVIRONMENTAL IMPLICATIONS ...... 5 5.1 Noise ...... 5 5.2 Air and Dust ...... 5 5.3 Water ...... 5 5.4 Solid Waste ...... 6 5.5 Ecology ...... 6 5.6 Landscape and Visual ...... 6 6. PREVIOIUSLY APPROVED SIMILAR ENVIRONMENTAL ASSESSMENTS ...... 6 7. CONCLUSIONS ...... 6
Drainage Improvement in Big Wave Bay Project Profile Drainage Services Department ______
LIST OF TABLES Table 1.1 Scale of Proposed Drainage Works…………………………………………..... 1
LIST OF APPENDICES Appendix 1 Location Plan and Extent of the Coastal Protection Area of Big Wave Bay Appendix 2 Species of Fauna (e.g. Fish) and Flora (e.g. Plant) in and near Big Wave Bay Stream
Drainage Improvement in Big Wave Bay Project Profile Drainage Services Department ______
1. PROJECT INFORMATION
1.1 Project Title
The project title is “Drainage Improvement in Big Wave Bay”.
1.2 Purpose and Nature of Project
The purpose of the project is to alleviate the current flooding problem at the public carpark of Big Wave Bay by upgrading the existing stormwater drainage system in accordance with the recommendation of the “Stormwater Drainage Master Plan Study in Southern Hong Kong Island”.
1.3 Name of Project Proponent
The project proponent is Drainage Services Department (DSD).
1.4 Location and Scale of Project
The project comprises the implementation of drainage improvement works for the existing drainage channels at the public carpark of Big Wave Bay. The location of the project is shown on Drawing No. SK-T2-09-019 attached in Appendix 1. The site photos regarding the site overview and the connection points of the proposed drainage channel and the existing Big Wave Bay stream are also attached. The scale of the project is detailed in Table 1.1 below.
Table 1.1 Scale of Proposed Drainage Works
Details of Proposed Channel/pipe Location Works Approx. Average Approx. Depth Length Base of Excavation Width Along the northern Construction of new 145m 1m Maximum and western side of drainage channels and 1.5m below the public carpark at associated catchpits, existing ground Big Wave Bay reconstruction of existing channel
Along the eastern Reconstruction of 45m 1m Maximum side of the public existing dilapidated 1.5m below carpark at Big Wave drainage channel existing ground Bay
Along middle of the Construction of new 35m 0.4m Maximum 1m public carpark at Big drainage channel below existing Wave Bay ground
1.5 Number and Types of Designated Project to be Covered by this Project Profile
The project is defined as designated projects under Item I.1(b)(ii) and (vi), Part I, Schedule 2 of the Environmental Impact Assessment Ordinance.
1.6 Name and Telephone Number of Contact Person
Enquiries regarding the project can be addressed to:
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Ms. LI Lai-kuen Telephone : 2594 7352 Fax : 2827 8700 Drainage Services Department
2. OUTLINE OF PLANNING AND IMPLEMENTATION PROGRAMME
2.1 Planning and Implementation of the Proposed Project
In-house staff of Drainage Services Department will be deployed for the contract management and works supervision of the proposed project. An approved Roads and Drainage civil works contractor will be employed to implement the proposed drainage improvement works.
2.2 Project Timetable
The detailed design of the project is completed. The target start date of construction is November 2010 due for completion in February 2011.
2.3 Site Activities Involved
Construction works will be carried out during daytime from 07:00 to 19:00 from Monday to Saturday except Public Holidays. Works will only start when the forecast weather of the coming week is good.
A small size excavator will be used to carry out excavation for the proposed new drainage channels. The trench of excavation will be about 1m wide x 1.5m deep, and the maximum length of each trench will be about 20m. The new channels will be built in traditional cast in-situ concrete.
The existing dilapidated channels will be demolished and reconstructed after the new drainage channels are completed and opened for stormwater flow. A hand-held pneumatic breaker will be used to break down the concrete of the existing channel into small pieces. Vehicles will be used for delivery of construction labour, materials and equipment.
During the operation phase, maintenance works will be regular clearance of debris inside the drainage channels and repair of damages to the drainage channels. These works will be minor in nature and will only be undertaken within the immediate vicinity of the drainage channels by manual means.
3. MAJOR ELEMENTS OF THE SURROUNDING ENVIRONMENT
3.1 Noise
Noise sensitive receivers (NSRs) identified within 300m from the project boundary are village houses located at about 6m to the north-western side of the nearest project boundary.
3.2 Air
Air sensitive receivers (ASRs) identified within 500m from the project boundary include village houses at about 6m to the north-western side of the nearest boundary, the Big Wave Bay Beach Office at about 40m to the south.
3.3 Ecology
The project site itself is adjoining a paved car parking area. However, its vicinity comprises a mix
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of rural catchment area, village, relatively undisturbed natural terrestrial habitats and natural/man-made intertidal habitats.
Ecological sensitive receivers include the relatively natural intertidal habitats, Coastal Protection Area (CPA) of Big Wave Bay and the Big Wave Bay Stream.
The CPA of Big Wave Bay is situated about 220m to the south-eastern side of the nearest project boundary.
Species of fauna (e.g. fish) and flora (e.g. trees, shrubs) of common interest recorded in and near Big Wave Bay Stream are listed in Appendix 2.
3.4 Cultural Heritage
The project is located in an area which is about 260m from the nearest boundary of an existing cultural heritage, the declared monument of Rock Carving at Big Wave Bay.
4. POSSIBLE IMPACTS ON THE ENVIRONMENT
4.1 Noise
During the construction phase, noise will be generated from site activities such as erection and removal of formwork for the drainage channels, concreting process, demolition works, loading and unloading of construction materials, plants and debris, as well as vehicular movements. However, the noise impact is considered to be transient and the project is of small scale with short duration of construction. With appropriate measures such as use of silenced-type equipment and limitation to the number of powered mechanical plant in operation at any one time, noise impact can be mitigated during construction.
During operation phase, only water will be flowing during rainy days and no noise will be generated. During maintenance phase, noise will be generated from clearance of debris and repair of damages to the drainage channels. Such maintenance works are of minor nature with short duration and are generally carried out by manual means. The maintenance works are also confined to the immediate vicinity of the drainage channels. As such, noise impact during operation and maintenance phases are considered negligible.
4.2 Air and Dust
During construction phase, dust will be generated from the demolition of the dilapidated drainage channels, excavation and vehicular movement. However, the impact is expected to be low due to the small scale of works, short duration, limited project area and the small quantity of earthwork and vehicles involved. Exhaust emissions from the electric generator will also be small due to the small number of electric generator deployed on site and the short duration of the demolition work. Water spray will also be adopted to suppress dust. The debris of the demolished drainage channel and the excavated soil will be loaded by manual means onto dump trucks equipped with mechanical cover for disposal.
Through the application of dust control measures and the use of properly maintained equipment, air and dust impacts are considered low.
No dust will be generated during operation phase. A small amount of dust may be generated during the implementation of maintenance works such as clearance of sediment and debris inside the drainage channels, and during repair of the damaged part of the concrete drainage channels. Such site activities are of minor nature with short duration. The impact on air quality is considered negligible.
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4.3 Water
During construction phase, the proposed drainage channel/pipe will be constructed in the dry. The connections to the existing Big Wave Bay Stream will be constructed at the last stage. Disturbance to the existing bank will be minimized by using sand bags as temporary cofferdam to enable construction. The sand bags will be removed upon completion of works. The existing dilapidated drainage channels will be demolished after the new drainage channels are completed and opened for stormwater flow. All construction works will be carried out in dry condition in the dry season. The exposed soil surface will be temporarily covered by canvas sheeting to avoid dust and drain away of soil. Hence, the project will not generate additional water and contaminated mud to the environment.
A public toilet with hand washing facilities an 5 shower room is located at the Big Wave Bay Beach, which about 40m from the project site. The scale of the construction is small with short duration. The number of workers is very limited. No temporary toilet, shower, hand washing facilities, kitchen and canteen will be provided during construction. As such, no effluent will be discharged into the existing Big Wave Bay Stream.
Vehicles will make use of the existing hard paved public carpark for temporary parking, loading and unloading. No significant amount of mud or soil material is expected to be brought onto the public road. No wheel washing facilities will be provided for the project. Hence, no contaminated water will be generated from the project.
During operation, the drainage channels will collect and convey the existing stormwater and surface runoff from the public carpark to Big Wave Bay Stream. No additional water will be generated from the project and no contamination to the Big Wave Bay Stream is anticipated.
4.4 Solid Waste
During construction phase, only a small amount of construction and demolition (C&D) materials such as broken pieces of dilapidated drainage channels, excavation materials, formwork for construction of channels and general refuse will be generated. Most of the C&D materials are inert and will be either re-used or disposed at landfill sites.
No dangerous chemical materials will be involved in the construction works duration.
During operation phase, the drainage channels will generate no solid waste. Catchpits will be provided to collect the sediment and debris in order to avoid blockage of the drainage system and minimize the amount of sediment and debris flowing to Big Wave Bay Stream. As most of the proposed channels are covered channels, municipal solid waste generated is minimal. Furthermore, maintenance works will be carried out to remove the sediment and debris inside the drainage channels and the broken pieces of the damaged part of the drainage channels. Such waste will be removed by manual means and disposed of immediately after the clearance works. No adverse environmental impacts are anticipated.
4.5 Ecology
The project will upgrade the existing drainage system to convey the existing stormwater from the public carpark to Big Wave Bay Stream. It will not alter the quantity and nature of the existing stormwater during operation. The flooding problem at the public carpark will be alleviated after completion of the project.
The new drainage channels will be connected to the Big Wave Bay Stream at its downstream end. The connection works is confined to the immediate vicinity of the drainage channel/pipe outlets and
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will not alter the overall stream bank. The works will be carried out in the dry season and in dry condition. In view of the small scale works with short duration, no impact on the freshwater fauna species and riparian vegetation during construction is anticipated.
During maintenance phase, minor repair works may be carried out at the connection points between the new channel/pipe and the bank of the Big Wave Bay Stream. Such minor repair works will be implemented in dry condition. No impact on the freshwater species and riparian vegatation is anticipated.
4.6 Cultural Heritage
The works will be confined to the immediate vicinity of the public carpark at Big Wave Bay. The project will cause no adverse impact to the existing cultural heritage, the declared monument of Rock Carving at Big Wave Bay at 260m away.
4.7 Landscape and Visual
During construction phase, the storage of excavated soil, construction plant and materials within construction site will create short term landscape and visual impact. However, the impact is expected to be low due to the small scale of works, short duration, limited project area and the small quantity of earthwork and plant involved.
During the operation phase, the drainage will be adjoining a paved Big Wave Bay car parking area at ground surface. There will be no landscape and visual impact.
4.8 Others
4.8.1 Odour
No odour impacts will be generated by the project.
4.8.2 Night-time Operations
All construction and maintenance works will be carried out during daytime from Monday to Saturday. No works will be implemented at night time and on Sunday and Public Holidays.
4.8.3 Dangerous Goods/ Hazardous Materials
No dangerous goods and hazardous materials will be involved in this project.
5. ENVIRONMENTAL PROTECTION MEASURES TO BE INCORPORATED IN THE DESIGN AND ANY FURTHER ENVIRONMENTAL IMPLICATIONS
5.1 Noise
The Contractor shall comply with and observe the Noise Control Ordinance and its subsidiary regulations in force in Hong Kong.
5.2 Air and Dust
The Contractor shall comply with Air Pollution Control Ordinance and its subsidiary regulations in force in Hong Kong.
5.3 Water
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The Contractor shall be obliged to fully comply with the Water Pollution Control Ordinance during construction and shall implement good site practice to control site drainage. All excavated soil materials, exposed trenches, materials and debris will be properly covered and protected to avoid being washed away into water.
5.4 Solid Waste
As for this small scale project, all construction and demolition waste will be segregated and re-used on site as far as practicable. The very small quantity of the remaining waste will be removed off site immediately after construction.
5.5 Ecology
The construction works will be confined to the immediate vicinity of the project. The size of excavation will be limited to the size of drainage channels so as to minimise disturbance to the ground, the bank and the fish species of the Big Wave Bay Stream. The works will be carried out in dry season and in dry condition to minimize soil that may be washed away by stormwater.
The drainage channels will be aligned with the shortest length as far as practicable without adverse impact to the existing trees and plants.
Good site practice under the close supervision of competent person will be adopted to minimize disturbance to the natural environment during the work.
5.6 Landscape and Visual
Implement good site practice such as site cleanliness, tidiness, proper storage of construction materials, minimize site area and, removal of debris immediately after construction and reinstatement of site area.
6. PREVIOIUSLY APPROVED SIMILAR ENVIRONMENTAL ASSESSMENTS
No previous EIA report has been approved or submitted for the project.
7. CONCLUSIONS
The environmental impacts of the project are unlikely to be adverse and the mitigation measures proposed above meet the requirements of the Technical Memorandum on Environmental Impact Assessment Process. As such, DSD is applying directly for an Environmental Permit under Section 5(11) of the EIAO.
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Col_pdf_cswp_v8.plt PLOTPEN.TBL $$colortable$$ $$rend_attr$$ C:\TEMP\dsd_pw\dms06051\sk_t2_09_019-0-col.dgn A4 297x210 Appendix 1 DRAINAGE IMPROVEMENT IN BIG WAV E BAY
Point 3
Point 2
Point 1
Layout Plan
Overview 1
Appendix 1
Overview 2
Big Wave Bay Stream
Proposed connection point
Existing U-channel to be replaced by 600mm U-channel
Connection Point 1
Appendix 1
Big Wave Bay Stream
Proposed 225mm U-channel
Proposed connection point
Connection Point 2
Big Wave Bay Stream
Proposed connection point
Existing U-channel to be Proposedreplaced by 600mm 600 mm U-ChanU-channel nel
Connection Point 3 Appendix 2
Species of Fauna (e.g. Fish) and Flora (e.g. Plant) in and near Big Wave Bay Stream
Part A. Fish Species recorded at Big Wave Bay Stream Oreochromis niloticus Poecilia reticulata Gambusia affinis Oreochromis mossambicus Rhinogobius duospilus Schistura fasciolata Eleotris oxycephala Xiphophorus variatus
Part B. Plant species recorded in the vicinity of the car park next to Big Wave Bay Stream Annona squamosa Archontophoenix alexandrae Araucaria heterophylla Averrhoa carambola Boehmeria nivea Carica papaya Caryota ochlandra Celtis sinensis Delonix regia Dimocarpus longan Ficus benjamina Ficus hispida Ficus microcarpa Hibiscus rosa-sinensis Hibiscus tiliaceus Leucaena leuocephala Litchi chinensis Macaranga tanarius Michelia alba Morus alba Musa sp. Osmanthus fragrans Phoenix roebelenii Psidium guajava Ravenala madagascariensis Salix babylonica Schefflera octophylla Sterculia lanceolata