Appendix K - Summary of Environmental Mitigation Implementation Schedule

Types of Impacts

Mitigation Measures

Status

Construction Dust
  • Any stockpile of dusty materials or stockpile of dusty material should be covered entirely by impervious sheeting or sprayed with water so as to maintain the entire surface wet.

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  • A stockpile of dusty materials should not extend beyond the pedestrian barriers, fencing or traffic cones.

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  • Vehicle washing facilities should be provided at every exit point.

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  • The area where vehicle washing takes place and the section of the road between the washing facilities and the exit point should be paved with concrete, bituminous materials or hardcores.

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  • Where a site boundary adjoins a road, street, service lane or other area accessible to the public, hoarding of not less than 2.4m high from ground level should be provided along the entire length of that portion of the site boundary except for a site entrance or exit.

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  • Every main haul road should be sprayed with water or a dust suppression chemical so as to maintain the entire road surface wet.

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

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  • Any stockpile of dusty materials should be either covered entirely be impervious sheeting, placed in an area sheltered on the top and the 3 sides or sprayed with water or a dust suppression chemical so as to maintain the entire surface wet.

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  • All dusty materials should be sprayed with water or a dust suppression chemical immediately prior to any loading, unloading or transfer operation so as to maintain the dusty materials wet.

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  • Every vehicle should be washed to remove any dusty materials from its body and wheels immediately before leaving a construction site.

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  • The working area of any excavation should be sprayed with water or a dust suppression chemical immediately before, during and immediately after the operation so as to maintain the entire surface wet.

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Construction Noise

·         Only well-maintained plant should be operated on –site and plant should be serviced regularly during the construction works.

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·         Machines and plant that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum.

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·         Plant know to emit noise strongly in one direction, should where possible, be orientated to direct noise away from the NSRS.

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  • Mobile plant should be sited as far away from NSRs as possible.

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  • Material stockpiles and other structures should be effectively utilised, where practicable, to screen noise from on-site construction activities.

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  • Use quite plant and Working Method

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  • Reduce the number of plant operating in critical areas close NSRs.

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  • Construct temporary and movable noise barriers

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Water Quality

 

Construction Runoff and Drainage

·         Use of sediment traps and the adequate maintenance of drainage systems to prevent flooding and overflow.

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·         Boundaries of critical areas of earthworks should be marked and surrounded by dykes or embankments for flood protection. Temporary ditches should be provided to facilities runoff discharge into the appropriate watercourses, via a silt retention pond. Permanent drainage channels should incorporate sediment basins or traps and baffles to enhance deposition rates.

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·         All temporary and permanent drainage pipes and culverts provided to facilitate runoff discharge should be adequately designed for the controlled release of storm flows. All sediment traps should be regularly cleaned and maintained. The temporarily diverted drainage should be reinstated to its original condition when the construction works has finished or the temporary diversion is no longer required

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  • Sand silt in the wash water from the wheel washing facilities, which ensure no earth, mud and debris is deposited on roads, should be settled out the removed before discharging into storm drains. A section of the road between the wheel washing bay and the public road should be paved with backfill to prevent wash water or other site runoff form entering public road drains.

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  • Oil interceptors should be provided in the drainage system and regularly emptied to prevent the release of oils and grease into the storm water drainage system after accidental spillage. The interceptor should have a bypass to prevent flushing during periods of heavy rain.

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  • Catchpits and perimeter channels shall be constructed in advance of site formation works and earthworks.

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  • Silt removal facilities, channels and manholes shall be suitably maintained with the deposited silt and grit being removed at least once a week, and at the onset of and after each rainstorm to ensure that these facilities are functioning properly at all times.

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  • Earthworks final surfaces shall be well compacted and the subsequent permanent work or surface protection shall be carried out immediately after the final surfaces are formed to prevent erosion caused by rainstorms. Appropriate intercepting channels shall be provided along the site boundary or at the locations agreed with the ET Leader. Rainwater pumped out from trenches or foundation excavations shall be discharged into silt removal facilities before discharge into storm drains.

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  • All generators, fuel and oil storage shall be within bunded areas. Drainage from the areas shall be connected to storm drains via a petrol interceptor.

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Tunnelling Work
  • Temporary open storage of excavated materials should be covered with tarpaulin or similar fabric during rainstorms. Any washout of construction or excavated materials form the drill and blast tunnelling work should be diverted to the drainage system via appropriate sediment traps.

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  • Ground water pumped out of tunnels should be discharged into the drainage channels which incorporated sediment traps to enhance deposition rates and to remove silt.

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  • Spend grouts used in diaphragm wall construction should be collected in a separate slurry collection system, reconditioned and reused wherever practicable. The disposal of used grouting materials will only be permitted if it is treated to the TM standards before discharge to the storm drains or disposal to landfill.

N/A

General Construction Activities

 
  • Debris and rubbish on site should be collected, handled and disposed of properly to avoid entering the water column and cause water quality impacts.

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  • All fuel tanks and storage areas will be provided with locks and be located on sealed areas (within bunds of a capacity equal to 110% of the storage capacity of the largest tank or 20% by volume of the fuel stored in that areas, whichever in the greatest).

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Sewage Effluent
  • Construction work force sewage discharges form fixed toilet facilities on-site should be connected to the nearby existing trunk sewer wherever feasible. However, for areas where existing trunk sewer is not available, it is recommended that appropriate and adequate on site portable chemical toilets should be provided by a licensed contractor who will be responsible for appropriate disposal and maintenance of these facilities.

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  • It is considered that sewage discharges could also be treated by on-site septic tanks and soakaway. Minimum clearance away form streams and catchments and other requirements for the proposed septic tank and soakaway should be referred to EPD’s Practice Note for Professional Persons, Drainage Plans.

N/A

Waste

 

General

 
  • Training and instruction shall be given at a site to construction staff to increase awareness and draw attention to waste management issues and the need to minimise waste generation. The training requirement shall be included in the site waste management plan.

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Storage, Collection and Transportation of Waste

 
  • Wastes shall be handled and stored in a manner to ensure that they are held securely without loss or leakage.

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  • Authorised or licensed waste hauliers shall be used and they shall only collect wastes prescribed by their permits.

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  • Waste shall be removed on a daily basis.

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  • Waste storage area shall be maintained and cleaned on a daily basis.

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  • Windblown litter and dust during transportation shall be minimised by either covering trucks or transporting wastes in enclosed containers.

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  • Obtain necessary waste disposal permits from the appropriate authorities if they are required.

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  • Wastes shall be disposed of at licensed waste disposal facilities.

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  • Develop procedure such as ticketing system to facilitate tracking of loads, particularly for chemical waste, and to ensure that illegal disposal of wastes does not occur.

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  • Maintain records of the quantities of wastes generated, recycled and disposed.

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Surplus Excavated Materials

 
  • Due to the high risk of loose material being washed into the existing nullah, stockpile materials should be properly compacted and covered from water erosion and located at least 10 away from the nullah wall.

N/A

Construction and Demolition (C&D) Waste

 
  • Careful design, planning and good site management shall be adopted to minimise over-ordering and generation of waste materials such as concrete grouts.

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  • The handling and disposal of bentonite slurries shall be undertaken in accordance with Practice Note for Professional Persons – Construction Site Drainage (ProPECC PN 1/94) on construction site drainage.

N/A
  • Construction and demolition (C&D) material shall be segregated to inert and non-inert parts. The inert portion shall re-used at areas of reclamation or land formation, or to public filling area shall such allocation is deemed necessary. The non-inert portion shall be disposed of to landfill.

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Chemical Waste

 
  • Chemical waste that is produce during construction shall be handled in accordance with the Cod of Practice on the Packaging, Handling and Storage of Chemical Wastes.

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  • Containers used for the storage of chemical wastes should:

a.       Be suitable for the substance they are holding, resistant to corrosion, maintained in a good condition, and securely closed;

b.       Have a capacity of less than 450 litres unless the specifications have been approved by the EPD;

c.       Display a label in English and Chinese in accordance with instructions prescribed in Schedule 2 of the Chemical Waste Regulations.

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  • The storage area for chemical wastes should:

a.       Be clearly labelled and used solely for the storage of chemical waste;

b.       Be enclosed on at least 3 sides;

c.       Have an impermeable floor and bunding of capacity to accommodate 110% of the volume of the largest container or 20% by volume of the chemical waste stored in the area, whichever is largest;

d.       Have adequate ventilation;

e.       Be covered to prevent rainfall entering (water collected within the bund must be tested and disposed as chemical waste if necessary);

f.        Be arranged so that incompatible materials are adequately separated.

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  • Disposal of chemical waste shall be via a licensed waste collector; and to a facility licensed to receive chemical waste; or a reuser of the waste (under approval from EPD).

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General Refuse

 
  • General refuse generated on-site shall be stored in enclosed bins or compaction unit separate from C&D and chemical wastes. A reputable waste collector shall be employed by the contractor to remove general refuse from the site, separately from C&D and chemical wastes, on a daily for every second day basis to minimise odour, pest and litter impacts. The burning of refuse on construction sites is prohibited by law.

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  • Reusable rather than disposable dishware shall be used if feasible.

N/A

Ecology
  • A sediment barrier shall be erected to minimize stream sedimentation at downstream of the project boundary of the Toll Plaza.

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  • Conduct a tree survey before commencement of the construction work.

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  • All measures recommended in the approved landscape proposals under Condition 2.4 in EP above shall be fully implemented in accordance with the details and time schedule set out in the submission.

N/A
  • Loss of the adjacent woodland due to temporary land take shall be returned to the original status immediately.

N/A
  • Wild and uncontrolled fire shall be strictly prohibited

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  • Fences shall be erected along the boundary of the construction sites at the Toll Plaza before commencement of works, to prevent tipping, vehicle movements, and encroachment of personnel onto adjacent wooded areas.

N/A

Landscape and Visual Impact
  • Landscape mitigation measure 1 (LMM1) – Construction programming and management. The periphery of the works areas at street level shall be managed so that they do not appear cluttered, untidy and unattractive and inconvenient to pedestrians. For example, all hoarding shall be colorfully designed with interesting motifs demonstrating the work of Highways Department. Hoardings with bland colours shall be avoided.

N/A
  • Landscape mitigation measure 2 (LMM2) – Advanced planting and erosion control works. Where possible, the transplantation of existing valuable trees, the stockpiling of topsoil, new planting and erosion control works shall be carried out as early as possible in the construction period instead of at the end. This will assist in maximizing the time for carrying out transplantation and new planting, resulting in a higher success rate for the survival of transplantation and new planting, resulting in a higher success rate for the survival of transplanted trees and the establishment of new screen trees. The stockpiling of topsoil will provide an abundant use of on-site material for growing media. During detailed design, the issue of stockpiling of topsoil in a manner that would avoid washing into the drainage scheme should be examined comprehensively.

N/A
  • Measurement of vibration would also be carried out on a need basis during the piling work

N/A

 

Remarks:

 

^              Compliance of mitigation measure;

 

X             Non-compliance of mitigation measure;

 

N/A         Not Applicable;

·              Non-compliance but rectified by the Contractor