10 IMPLEMENTATION SCHEDULE OF MITIGATION MEASURES

10.1 Introduction

10.1.1 This chapter presents the implementation schedule of mitigation measures for the project. Table 10.1 summarizes the details of the recommended mitigation measures for all works areas. For each recommended mitigation measures, both the location and timing for the measure have clearly been identified as well as the parties responsible for implementing the measure and for maintenance (where applicable).

Table 10.1 Implementation Schedule of Mitigation Measures

EIA Ref.	Environmental Protection Measures	Location of the Measures	Implementation Agent	Implementation Stage					Relevant Legislation and Guidelines
EIA Ref.	Environmental Protection Measures	Location of the Measures	Implementation Agent	Des	C	O	Dec		Relevant Legislation and Guidelines
Air Quality (Construction Phase)
4.6.1	Watering once per hour on active construction work areas, and the watering application intensity is estimated to be 0.152 L/m² (tentatively) so as to achieve a dust removal efficiency of 87.5%.	Active works area	CEDD/Contractor		ü				EIAO-TM, AQOs
4.7.1 – 4.7.2	To ensure compliance with the guideline level and AQO at the ASRs, the Air Pollution Control (Construction Dust) Regulation should be implemented and good site practices should be incorporated in the contract clauses to minimize construction dust impact. A number of below dust suppression measures are proposed to be implemented. Ÿ Any excavated or stockpile of dusty material should be covered entirely by impervious sheeting or sprayed with water to maintain the entire surface wet and then removed or backfilled or reinstated where practicable within 24 hours of the excavation or unloading; Ÿ Any dusty material remaining after a stockpile is removed should be wetted with water and cleared from the surface of roads; Ÿ A stockpile of dusty material should not extend beyond the pedestrian barriers, fencing or traffic cones; Ÿ The load of dusty materials on a vehicles leaving a construction site should be covered entirely by impervious sheeting to ensure that the dusty materials do not leak form the vehicle; Ÿ Where practicable, vehicles washing facilities including a high pressure water jet should be provided at every discernible or designated vehicle exit point. The area where vehicle washing takes place and the road section between the washing facilities and the exit point should be paved with concrete, bituminous materials or hardcores; Ÿ When there are open excavation and reinstatement works, hoarding of not less than 2.4m high should be provided as far as practicable along the site boundary with provision for public crossing. Good site practice shall also be adopted by the Contractor to ensure the conditions of the hoardings are properly maintained throughout the construction period; Ÿ The portion of any road leading only to construction site that is within 30m of a vehicle entrance or exit should be kept clear of dusty materials; Ÿ Surfaces where any pneumatic or power-driven drilling, cutting, polishing or other mechanical breaking operation takes place should be sprayed with water or a dust suppression chemical continuously; Ÿ Any area that involves demolition activities should be sprayed with water or a dust suppression chemical immediately prior to, during and immediately after the activities so as to maintain the entire surface wet; Ÿ Where a scaffolding is erected around the perimeter of a building under construction, effective dust screens, sheeting or netting should be provided to enclose the scaffolding from the ground floor level of the building, or a canopy should be provided from the first floor level up to the highest level of the scaffolding; Ÿ Any skip hoist for material transport should be totally enclosed by impervious sheeting; Ÿ Every stock of more than 20 bags of cement or dry pulverised fuel ash (PFA) should be covered entirely by impervious sheeting or placed in an area sheltered on the top and the three sides; Ÿ Cement or dry PFA delivered in bulk should be stored in a closed silo fitted with an audible high level alarm which is interlocked with the material filling line and no overfilling is allowed; and Ÿ Exposed earth should be properly treated by compaction, turfing, hydroseeding, vegetation planting or sealing with latex, vinyl, bitumen, shortcrete or other suitable surface stabiliser within six months after the last construction activity on the construction site or part of the construction site where the exposed earth lies.	All works area	CEDD/Contractor		ü				Air Pollution Control (Construction Dust) Regulation
Air Quality (Operational Phase)
N/A	N/A	N/A	N/A						N/A
Noise (Construction Phase)
5.10.2	The future contractors should follow the requirements set out in the “Recommended Environmental Pollution Control Clauses” published by EPD and adopt the following good site practices to minimise construction noise impacts on the surrounding environment during construction phase: Ÿ Only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction program. Ÿ Silencers or mufflers on construction equipment should be utilized and should be properly maintained during the construction program. Ÿ Mobile plant, if any, should be sited as far from noise sensitive receivers (NSRs) as possible. Ÿ 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. Ÿ Plant known to emit noise strongly in one direction should, wherever possible, be orientated so that the noise is directed away from the nearby NSRs. Ÿ Material stockpiles and other structures should be effectively utilized, wherever practicable, in screening noise from on-site construction activities.	All works area	CEDD/Contractor		ü				EIAO Guidance Note No. 9/2004 “Preparation of Construction Noise Impact Assessment under the Environmental Impact Assessment Ordinance” (GN 9/2004)
Noise (Operational Phase)
5.10.3	The following noise reduction measures are recommended to consider as far as practicable during the processes of detailed design and procurement for the ventilation shafts: Ÿ Choose quieter plant such as those which have been effectively silenced. Ÿ Include noise levels specification when ordering new plant (including chillier and E/M equipment). Ÿ Locate fixed plant/louver away from any NSRs as far as practicable. Ÿ Locate fixed plant in walled plant rooms or in specially designed enclosures. Ÿ Locate noisy machines in a basement or a completely separate building. Ÿ Install direct noise mitigation measures including silencers, acoustic louvers and acoustic enclosure where necessary. Ÿ Develop and implement a regularly scheduled plant maintenance programme so that equipment is properly operated and serviced in order to maintain controlled level of noise. The programme should be implemented by properly trained personnel.	Ventilation shafts of rock cavern	CEDD/Contractor	ü	ü				EIAO-TM
5.12.2	Prior to the operational phase of the rock cavern, a commissioning test for the ventilation shaft should be conducted to ensure compliance with the relevant noise criteria.	Ventilation shafts of rock cavern	CEDD/LCSD		ü				EIAO-TM
Water Quality (Construction Phase)
6.9.1 – 6.9.13	Construction Site Run-off and General Construction Activities Boring and Drilling Water Ÿ Water used in ground boring and drilling for site investigation or rock / soil anchoring should as far as practicable be re-circulated after sedimentation. When there is a need for final disposal, the wastewater should be discharged into storm drains via silt removal facilities. Wheel Washing Water Ÿ All vehicles and plant should be cleaned before they leave a construction site to minimize the deposition of earth, mud, debris on roads. A wheel washing bay should be provided at every site exit if practicable and wash-water should have sand and silt settled out or removed before discharging into storm drains. The section of construction road between the wheel washing bay and the public road should be paved with backfall to reduce vehicle tracking of soil and to prevent site run-off from entering public road drains. Rubbish and Litter Ÿ Good site practices should be adopted to remove rubbish and litter from construction sites so as to prevent the rubbish and litter from spreading from the site area. It is recommended to clean the construction sites on a regular basis. Construction Site Run-off Ÿ The site practices outlined in ProPECC PN 1/94 “Construction Site Drainage” should be followed as far as practicable to minimise surface run-off and the chance of erosion. The following measures are recommended to protect water quality and sensitive uses of the coastal area, and when properly implemented should be sufficient to adequately control site discharges so as to avoid water quality impact: Ÿ Surface run-off from construction sites should be discharged into storm drains via adequately designed sand/silt removal facilities such as sand traps, silt traps and sedimentation basins. Channels or earth bunds or sand bag barriers should be provided on site to properly direct stormwater to such silt removal facilities. Perimeter channels at site boundaries should be provided on site boundaries where necessary to intercept storm run-off from outside the site so that it will not wash across the site. Catchpits and perimeter channels should be constructed in advance of site formation works and earthworks. Ÿ Silt removal facilities, channels and manholes should be maintained and the deposited silt and grit should be removed regularly, at the onset of and after each rainstorm to prevent local flooding. Any practical options for the diversion and re-alignment of drainage should comply with both engineering and environmental requirements in order to provide adequate hydraulic capacity of all drains. Minimum distance of 100m should be maintained between the discharge points of construction site run-off and the existing saltwater intakes. No effluent will be discharged into typhoon shelter. Ÿ Construction works should be programmed to minimize soil excavation works in rainy seasons (April to September). If excavation in soil cannot be avoided in these months or at any time of year when rainstorms are likely, for the purpose of preventing soil erosion, temporary exposed slope surfaces should be covered e.g. by tarpaulin, and temporary access roads should be protected by crushed stone or gravel, as excavation proceeds. Intercepting channels should be provided (e.g. along the crest / edge of excavation) to prevent storm runoff from washing across exposed soil surfaces. Arrangements should always be in place in such a way that adequate surface protection measures can be safely carried out well before the arrival of a rainstorm. Ÿ Earthworks final surfaces should be well compacted and the subsequent permanent work or surface protection should be carried out immediately after the final surfaces are formed to prevent erosion caused by rainstorms. Appropriate drainage like intercepting channels should be provided where necessary. Ÿ Measures should be taken to minimize the ingress of rainwater into trenches. If excavation of trenches in wet seasons is necessary, they should be dug and backfilled in short sections. Rainwater pumped out from trenches or foundation excavations should be discharged into storm drains via silt removal facilities. Ÿ Construction materials (e.g. aggregates, sand and fill material) on sites should be covered with tarpaulin or similar fabric during rainstorms. Ÿ Manholes (including newly constructed ones) should always be adequately covered and temporarily sealed so as to prevent silt, construction materials or debris from getting into the drainage system, and to prevent storm run-off from getting into foul sewers. Discharge of surface run-off into foul sewers must always be prevented in order not to unduly overload the foul sewerage system. Ÿ Good site practices should be adopted to remove rubbish and litter from construction sites so as to prevent the rubbish and litter from spreading from the site area. It is recommended to clean the construction sites on a regular basis. Site Effluent Ÿ There is a need to apply to EPD for a discharge licence for discharge of effluent from the construction site under the WPCO. The discharge quality must meet the requirements specified in the discharge licence. All the runoff and wastewater generated from the works areas should be treated so that it satisfies all the standards listed in the TM-DSS. The beneficial uses of the treated effluent for other on-site activities such as dust suppression, wheel washing and general cleaning etc., can minimise water consumption and reduce the effluent discharge volume. If monitoring of the treated effluent quality from the works areas is required during the construction phase of the Project, the monitoring should be carried out in accordance with the relevant WPCO licence which is under the ambit of regional office (RO) of EPD.	All works area	CEDD/Contractor		ü				ProPECC PN 1/94 Construction Site Drainage TM-DSS Water Pollution Control Ordinance
6.9.14 – 6.9.16	Accidental Spillage and Potential Contamination of Surface Water and Groundwater Ÿ Contractor must register as a chemical waste producer if chemical wastes would be produced from the construction activities. The Waste Disposal Ordinance (Cap 354) and its subsidiary regulations in particular the Waste Disposal (Chemical Waste) (General) Regulation, should be observed and complied with for control of chemical wastes. Ÿ Any service shop and maintenance facilities should be located on hard standings within a bunded area, and sumps and oil interceptors should be provided. Maintenance of vehicles and equipment involving activities with potential for leakage and spillage should only be undertaken within the areas appropriately equipped to control these discharges. Ÿ Disposal of chemical wastes should be carried out in compliance with the Waste Disposal Ordinance. The Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes published under the Waste Disposal Ordinance details the requirements to deal with chemical wastes. General requirements are given as follows: - Suitable containers should be used to hold the chemical wastes to avoid leakage or spillage during storage, handling and transport; - Chemical waste containers should be suitably labelled, to notify and warn the personnel who are handling the wastes, to avoid accidents; and - Storage area should be selected at a safe location on site and adequate space should be allocated to the storage area.	All works area	CEDD/Contractor		ü				Waste Disposal Ordinance Waste Disposal (Chemical Waste) (General) Regulation The Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes
6.9.17 – 6.9.18	Sewage Effluent from Construction Workforce Ÿ The construction workforce on site will generate sewage. It is recommended to provide sufficient chemical toilets in the works areas. A licensed waste collector should be deployed to clean the chemical toilets on a regular basis. Ÿ Notices should be posted at conspicuous locations to remind the workers not to discharge any sewage or wastewater into the surrounding environment. Regular environmental audit of the construction site will provide an effective control of any malpractices and can encourage continual improvement of environmental performance on site. It is anticipated that sewage generation during the construction phase of the project would not cause water pollution problem after undertaking all required measures.	All works area	CEDD/Contractor		ü				Water Pollution Control Ordinance
6.9.19	Construction Works in Close Proximity of Inland Waters Ÿ The practices outlined in ETWB TC (Works) No. 5/2005 “Protection of natural streams/rivers from adverse impacts arising from construction works” should also be adopted where applicable to minimize the water quality impacts upon any natural streams or surface water systems. Relevant mitigation measures from the ETWB TC (Works) No. 5/2005 are listed below: - Construction works close to the inland waters should be carried out in dry season as far as practicable where the flow in the surface channel or stream is low. - The use of less or smaller construction plants may be specified in areas close to the water courses to reduce the disturbance to the surface water. - Temporary storage of materials (e.g. equipment, chemicals and fuel) and temporary stockpile of construction materials should be located well away from any water courses during carrying out of the construction works. - Stockpiling of construction materials and dusty materials should be covered and located away from any water courses. - Construction debris and spoil should be covered up and/or disposed of as soon as possible to avoid being washed into the nearby water receivers. - Proper shoring may need to be erected in order to prevent soil or mud from slipping into the watercourses.	All works area	CEDD/Contractor		ü				Water Pollution Control Ordinance
6.9.20 – 6.9.23	Infiltration of Groundwater Ÿ Appropriate measures during the cavern construction should be implemented to minimize the groundwater infiltration. The water control strategies include: - Probing Ahead: As normal practice, the Contractor will undertake rigorous probing of the ground ahead of excavation works to identify zones of significant water inflow. The probe drilling results will be evaluated to determine specific grouting requirements in line with the tunnel / cavern advance. In such zones of significant water inflow that could occur as a result of discrete, permeable features, the intent would be to reduce overall inflow by means of cut-off grouting executed ahead of the tunnel / cavern advance. - Pre-grouting: Where water inflow quantities are excessive, pre-grouting will be required to reduce the water inflow into the tunnel / cavern. The pre-grouting will be achieved via a systematic and carefully specified protocol of grouting. - In principle, the grout pre-treatment would be designed on the basis of probe hole drilling ahead of the tunnel / cavern face. - The installation of waterproof lining would also be adopted after the formation of the tunnels and caverns. Ÿ In the event of excessive infiltration being observed as a result of the tunnelling or excavation works even after incorporation of the water control strategies, post-grouting should be applied as far as practicable as described below: - Post-grouting: Groundwater drawdown will be most likely due to inflows of water into the tunnel / cavern that have not been sufficiently controlled by the pre-grouting measures. Where this occurs post grouting will be undertaken before the lining is cast. Whilst unlikely to be required in significant measure, such a contingency should be allowed for reduction in permeability of the tunnel / cavern surround (by grouting) to limit inflow to acceptable levels. Ÿ The practical groundwater control measures stated above are proven technologies and have been extensively applied in other past projects. These measures or other similar methods, as approved by the Engineer to suit the works condition shall be applied to minimize the groundwater infiltration. Ÿ In case seepage of groundwater occurs, groundwater should be pumped out from works areas and discharged to the storm system via silt trap. Uncontaminated groundwater from dewatering process should also be discharged to the storm system via silt removal facilities.	All works area	CEDD/Contractor		ü				Water Pollution Control Ordinance
Water Quality (Operational Phase)
6.9.24 – 6.9.25	Ÿ All the sewage and wastewater generated from the future development should be properly collected and diverted to public sewers for proper treatment and disposal. Discharge of any commercial effluent to the public sewers will be subject to control under the WPCO and the relevant dischargers shall apply to EPD for a discharge licence for discharge of commercial effluent and the discharge quality must satisfy all the standards listed in the TM-DSS and meet the requirements specified in the discharge licence. The practices outlined in ProPECC PN 5/93 for handling, treatment and disposal of Operational stage effluent should also be adopted where applicable.	All works area	CEDD/Contractor			ü			Water Pollution Control Ordinance ProPECC PN 5/93
Sewerage and Sewage Treatment (Construction)
N/A	N/A	N/A	N/A						N/A
Sewerage and Sewage Treatment (Operational Phase)
N/A	N/A	N/A	N/A						N/A
Waste Management (Construction Phase)
8.6.1 – 8.6.3	Good Site Practices Ÿ Appropriate waste handling, transportation and disposal methods for all waste arising generated during the construction works for the Project should be implemented to ensure that construction wastes do not enter the nearby streams or drainage channel. Ÿ It is anticipated that adverse impacts would not arise on the construction site, provided that good site practices are strictly followed. Recommendations for good site practices during the construction activities include: - Nomination of approved personnel, such as a site manager, to be responsible for good site practices, and making arrangements for collection of all wastes generated at the site and effective disposal to an appropriate facility. - Training of site personnel in proper waste management and chemical waste handling procedures. - Provision of sufficient waste reception/ disposal points, of a suitable vermin-proof design that minimises windblown litter. - Arrangement for regular collection of waste for transport off-site and final disposal. - Appropriate measures to minimise windblown litter and dust during transportation of waste by either covering trucks or by transporting wastes in enclosed containers. - Regular cleaning and maintenance programme for drainage systems, sumps and oil interceptors. - A recording system for the amount of wastes generated, recycled and disposed (including the disposal sites) should be proposed. - A Waste Management Plan should be prepared and should be submitted to the Engineer for approval. One may make reference to ETWB TCW No. 19/2005 for details. Ÿ In order to monitor the disposal of C&D materials at landfills and public filling areas, as appropriate, and to control fly tipping, a trip-ticket system should be included as one of the contractual requirements to be implemented by an Environmental Team undertaking the Environmental Monitoring and Audit work. One may take reference to DEVB TCW No.6/2010 for details.	All works area	CEDD/Contractor		ü				Waste Disposal Ordinance DEVB TCW No. 6/2010, ETWB TCW No. 19/2005
8.6.4 – 8.6.5	Waste Reduction Measures Ÿ Good management and control of construction site activities/ processes can minimise the generation of waste. Waste reduction is best achieved at the planning and design stage, as well as by ensuring the implementation of good site practices. Recommendations to achieve waste reduction include: - Segregate and store different types of construction related waste in different containers, skips or stockpiles to enhance reuse or recycling of materials and their proper disposal. - Provide separate labelled bins to segregate recyclable waste such as aluminium cans from other general refuse generated by the work force, and to encourage collection by individual collectors. - Any unused chemicals or those with remaining functional capacity shall be recycled. - Maximising the use of reusable steel formwork to reduce the amount of construction and demolition (C&D) materials. - Prior to disposal of C&D waste, it is recommended that wood, steel and other metals shall be separated for re-use and / or recycling to minimise the quantity of waste to be disposed of to landfill. - Adopt proper storage and site practices to minimise the potential for damage to, or contamination of, construction materials. - Plan the delivery and stock of construction materials carefully to minimise the amount of waste generated. - Minimize over ordering of concrete, mortars and cement grout by doing careful check before ordering. Ÿ In addition to the above measures, other specific mitigation measures are recommended below to minimise environmental impacts during handling, transportation and disposal of wastes.	All works areas	CEDD/Contractor	ü	ü				Waste Disposal Ordinance ETWB TCW No. 19/2005
8.6.6 – 8.6.8	Construction and Demolition Materials Ÿ The C&D materials generated from demolition works of slope and cavern should be sorted on-site into inert C&D materials (that is, public fill) and C&D waste. To minimise the impact resulting from collection and transportation of C&D materials as far as practicable. C&D waste, such as wood, plastic, steel and other metals should be reused or recycled and, as a last resort, disposed to landfill. A suitable area should be designated within the site for temporary stockpiling of C&D materials and to facilitate the sorting process. Within the stockpile areas, the following measures should be taken to control potential environmental impacts or nuisance: - Waste such as soil should be handled and stored well to ensure secure containment; - Covering materials during heavy rainfall; - Stockpiling area should be provided with covers and water spraying system to prevent materials from wind-blown or being washed away; - Locating stockpiles to minimise potential visual impacts; and - Minimising land intake of stockpile areas as far as possible. General Refuse Ÿ General refuse should be stored in enclosed bins or compaction units separate from C&D materials. A reputable waste collector should be employed by the contractor to remove general refuse from the site, separately from C&D materials. An enclosed and covered area is preferred to reduce the occurrence of 'wind blown' light material. Chemical Wastes Ÿ If chemical wastes were to be produced at the construction site, the Contractor would be required to register with the EPD as a Chemical Waste Producer, and to follow the guidelines stated in the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes. Good quality containers compatible with the chemical wastes should be used, and incompatible chemicals should be stored separately. Appropriate labels should be securely attached on each chemical waste container indicating the corresponding chemical characteristics of the waste such as explosive, flammable, oxidizing, irritant, toxic, harmful, corrosive, etc. The Contractor shall use a licensed collector to transport the chemical wastes. The licensed collector shall deliver the waste to the Chemical Waste Treatment Centre at Tsing Yi, or other licensed facility, in accordance with the Waste Disposal (Chemical Waste) (General) Regulation.	All works areas	CEDD/Contractor		ü				Waste Disposal Ordinance Waste Disposal (Chemical Waste) (General) Regulation Public Health and Municipal Services Ordinance (Cap. 132) - Public Cleansing and Prevention of Nuisances Regulation Land (Miscellaneous Provisions) Ordinance Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes Packaging, Labelling and Storage of Chemical Wastes
Waste Management (Operational Phase)
8.6.9	Ÿ Sufficient recycling containers are recommended to be provided at suitable locations to encourage recycling of such waste as aluminium cans, plastics and waste paper.	Within site boundary	LCSD			ü		EIAO-TM
Landscape and Visual (Construction Phase)
9.8.3	Ÿ Erection of decorative screen hoarding.	All works area	CEDD/Contractor		ü				EIAO-TM
Landscape and Visual (Operational Phase)
9.8.3	Ÿ Sensitive and aesthetically pleasing design as regard to the form, height, material and finishes which should be visually unobtrusive, non-reflective compatible with surrounding context shall be incorporated to design of cavern entrance and associated infrastructure facilities.	Within site boundary	CEDD/Original maintenance/management parties of the areas concerned	ü		ü			EIAO Guidance Note No. 8/2010
9.8.3	Ÿ Landscape treatments on slope to provide vertical greening with climber to enhance the landscape and visual amenity value of proposed man made slope.	Within site boundary	CEDD/LCSD/HyD/LandsD/HD	ü		ü			GEO publication No. 1/2011
9.8.3	Ÿ Compensatory trees planting in accordance with ETWB TCW No. 10/2013 and Shrubs Planting shall be incorporated to enhance the landscape and visual amenity value of entrance area of the proposed cavern.	Within site boundary	CEDD/LCSD	ü		ü			ETWB TCW No. 10/2013

10 IMPLEMENTATION SCHEDULE OF MITIGATION MEASURES

10.1 Introduction

Ÿ Any excavated or stockpile of dusty material should be covered entirely by impervious sheeting or sprayed with water to maintain the entire surface wet and then removed or backfilled or reinstated where practicable within 24 hours of the excavation or unloading;

Ÿ Any dusty material remaining after a stockpile is removed should be wetted with water and cleared from the surface of roads;

Ÿ A stockpile of dusty material should not extend beyond the pedestrian barriers, fencing or traffic cones;

Ÿ The load of dusty materials on a vehicles leaving a construction site should be covered entirely by impervious sheeting to ensure that the dusty materials do not leak form the vehicle;

Ÿ The portion of any road leading only to construction site that is within 30m of a vehicle entrance or exit should be kept clear of dusty materials;

Ÿ Surfaces where any pneumatic or power-driven drilling, cutting, polishing or other mechanical breaking operation takes place should be sprayed with water or a dust suppression chemical continuously;

Ÿ Any area that involves demolition activities should be sprayed with water or a dust suppression chemical immediately prior to, during and immediately after the activities so as to maintain the entire surface wet;

Ÿ Any skip hoist for material transport should be totally enclosed by impervious sheeting;

Ÿ Every stock of more than 20 bags of cement or dry pulverised fuel ash (PFA) should be covered entirely by impervious sheeting or placed in an area sheltered on the top and the three sides;

Ÿ Cement or dry PFA delivered in bulk should be stored in a closed silo fitted with an audible high level alarm which is interlocked with the material filling line and no overfilling is allowed; and

Ÿ Only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction program.

Ÿ Silencers or mufflers on construction equipment should be utilized and should be properly maintained during the construction program.

Ÿ Mobile plant, if any, should be sited as far from noise sensitive receivers (NSRs) as possible.

Ÿ 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.

Ÿ Plant known to emit noise strongly in one direction should, wherever possible, be orientated so that the noise is directed away from the nearby NSRs.

Ÿ Material stockpiles and other structures should be effectively utilized, wherever practicable, in screening noise from on-site construction activities.

Ÿ Choose quieter plant such as those which have been effectively silenced.

Ÿ Include noise levels specification when ordering new plant (including chillier and E/M equipment).

Ÿ Locate fixed plant/louver away from any NSRs as far as practicable.

Ÿ Locate fixed plant in walled plant rooms or in specially designed enclosures.

Ÿ Locate noisy machines in a basement or a completely separate building.

Ÿ Install direct noise mitigation measures including silencers, acoustic louvers and acoustic enclosure where necessary.

Ÿ Develop and implement a regularly scheduled plant maintenance programme so that equipment is properly operated and serviced in order to maintain controlled level of noise. The programme should be implemented by properly trained personnel.

Ÿ Water used in ground boring and drilling for site investigation or rock / soil anchoring should as far as practicable be re-circulated after sedimentation. When there is a need for final disposal, the wastewater should be discharged into storm drains via silt removal facilities.

Ÿ Good site practices should be adopted to remove rubbish and litter from construction sites so as to prevent the rubbish and litter from spreading from the site area. It is recommended to clean the construction sites on a regular basis.

Ÿ Construction materials (e.g. aggregates, sand and fill material) on sites should be covered with tarpaulin or similar fabric during rainstorms.

Ÿ Good site practices should be adopted to remove rubbish and litter from construction sites so as to prevent the rubbish and litter from spreading from the site area. It is recommended to clean the construction sites on a regular basis.

- Suitable containers should be used to hold the chemical wastes to avoid leakage or spillage during storage, handling and transport;

- Chemical waste containers should be suitably labelled, to notify and warn the personnel who are handling the wastes, to avoid accidents; and

- Storage area should be selected at a safe location on site and adequate space should be allocated to the storage area.

Ÿ The construction workforce on site will generate sewage. It is recommended to provide sufficient chemical toilets in the works areas. A licensed waste collector should be deployed to clean the chemical toilets on a regular basis.

- Construction works close to the inland waters should be carried out in dry season as far as practicable where the flow in the surface channel or stream is low.

- The use of less or smaller construction plants may be specified in areas close to the water courses to reduce the disturbance to the surface water.

- Temporary storage of materials (e.g. equipment, chemicals and fuel) and temporary stockpile of construction materials should be located well away from any water courses during carrying out of the construction works.

- Stockpiling of construction materials and dusty materials should be covered and located away from any water courses.

- Construction debris and spoil should be covered up and/or disposed of as soon as possible to avoid being washed into the nearby water receivers.

- Proper shoring may need to be erected in order to prevent soil or mud from slipping into the watercourses.

Ÿ Appropriate measures during the cavern construction should be implemented to minimize the groundwater infiltration. The water control strategies include:

- Pre-grouting: Where water inflow quantities are excessive, pre-grouting will be required to reduce the water inflow into the tunnel / cavern. The pre-grouting will be achieved via a systematic and carefully specified protocol of grouting.

- In principle, the grout pre-treatment would be designed on the basis of probe hole drilling ahead of the tunnel / cavern face.

- The installation of waterproof lining would also be adopted after the formation of the tunnels and caverns.

Ÿ In the event of excessive infiltration being observed as a result of the tunnelling or excavation works even after incorporation of the water control strategies, post-grouting should be applied as far as practicable as described below:

Ÿ The practical groundwater control measures stated above are proven technologies and have been extensively applied in other past projects. These measures or other similar methods, as approved by the Engineer to suit the works condition shall be applied to minimize the groundwater infiltration.

Ÿ In case seepage of groundwater occurs, groundwater should be pumped out from works areas and discharged to the storm system via silt trap. Uncontaminated groundwater from dewatering process should also be discharged to the storm system via silt removal facilities.

Ÿ Appropriate waste handling, transportation and disposal methods for all waste arising generated during the construction works for the Project should be implemented to ensure that construction wastes do not enter the nearby streams or drainage channel.

Ÿ It is anticipated that adverse impacts would not arise on the construction site, provided that good site practices are strictly followed. Recommendations for good site practices during the construction activities include:

- Nomination of approved personnel, such as a site manager, to be responsible for good site practices, and making arrangements for collection of all wastes generated at the site and effective disposal to an appropriate facility.

- Training of site personnel in proper waste management and chemical waste handling procedures.

- Provision of sufficient waste reception/ disposal points, of a suitable vermin-proof design that minimises windblown litter.

- Arrangement for regular collection of waste for transport off-site and final disposal.

- Appropriate measures to minimise windblown litter and dust during transportation of waste by either covering trucks or by transporting wastes in enclosed containers.

- Regular cleaning and maintenance programme for drainage systems, sumps and oil interceptors.

- A recording system for the amount of wastes generated, recycled and disposed (including the disposal sites) should be proposed.

- A Waste Management Plan should be prepared and should be submitted to the Engineer for approval. One may make reference to ETWB TCW No. 19/2005 for details.

Ÿ Good management and control of construction site activities/ processes can minimise the generation of waste. Waste reduction is best achieved at the planning and design stage, as well as by ensuring the implementation of good site practices. Recommendations to achieve waste reduction include:

- Segregate and store different types of construction related waste in different containers, skips or stockpiles to enhance reuse or recycling of materials and their proper disposal.

- Provide separate labelled bins to segregate recyclable waste such as aluminium cans from other general refuse generated by the work force, and to encourage collection by individual collectors.

- Any unused chemicals or those with remaining functional capacity shall be recycled.

- Maximising the use of reusable steel formwork to reduce the amount of construction and demolition (C&D) materials.

- Prior to disposal of C&D waste, it is recommended that wood, steel and other metals shall be separated for re-use and / or recycling to minimise the quantity of waste to be disposed of to landfill.

- Adopt proper storage and site practices to minimise the potential for damage to, or contamination of, construction materials.

- Plan the delivery and stock of construction materials carefully to minimise the amount of waste generated.

- Minimize over ordering of concrete, mortars and cement grout by doing careful check before ordering.

Ÿ In addition to the above measures, other specific mitigation measures are recommended below to minimise environmental impacts during handling, transportation and disposal of wastes.

- Waste such as soil should be handled and stored well to ensure secure containment;

- Covering materials during heavy rainfall;

- Stockpiling area should be provided with covers and water spraying system to prevent materials from wind-blown or being washed away;

- Locating stockpiles to minimise potential visual impacts; and

- Minimising land intake of stockpile areas as far as possible.

Ÿ Sufficient recycling containers are recommended to be provided at suitable locations to encourage recycling of such waste as aluminium cans, plastics and waste paper.

Ÿ Erection of decorative screen hoarding.

Ÿ Sensitive and aesthetically pleasing design as regard to the form, height, material and finishes which should be visually unobtrusive, non-reflective compatible with surrounding context shall be incorporated to design of cavern entrance and associated infrastructure facilities.

Ÿ Landscape treatments on slope to provide vertical greening with climber to enhance the landscape and visual amenity value of proposed man made slope.

Ÿ Compensatory trees planting in accordance with ETWB TCW No. 10/2013 and Shrubs Planting shall be incorporated to enhance the landscape and visual amenity value of entrance area of the proposed cavern.