5.                  ECOLOGY


5.1              According to the assessment presented in Section 6 of the EIA Report for the Project, much of the works would be confined within existing site boundaries or to developed/disturbed areas of low ecological value such as along the South Lantau Road. It was anticipated that provided that good site practices and mitigation measures to minimise impacts are strictly observed, ecological impacts would be minimal.

5.2              The main concern arising from the Project was vegetation clearance and disturbance within woodland habitat at Pui O associated with the non-designated project of raw water mains installation. The works area within woodland habitat would amount to approximately 0.4ha.  Within this woodland habitat, recent surveys found several individuals of two shrub/tree species of conservation interest namely Pavetta hongkongensis and Aquilaria sinensis.

5.3              Regular site audit of mitigation measures for good site practice will serve to minimise ecological impacts. Reinstatement of disturbed areas through replanting of trees and vegetation as specified in Section 6 of this Manual, will also minimise ecological impacts.

5.4              General EM&A requirements concerning protection of the two species of shrub/trees of conservation importance are also recommended in this section for the raw water mains installation at Pui O. However, the details on arrangements for transplantation will require inclusion at the detailed design phase.

Mitigation Measures

5.5              The following mitigation measures were recommended to minimise ecological impacts.  These mitigation measures are common to both the designated project and non-designated project elements, apart from the measure to avoid disturbance to the two identified species of conservation interest within the woodland habitat at Pui O, which is specific to the raw water mains installation at Pui O:.

Mitigation to minimise impacts on vegetation in woodland

·        All trees should be preserved as far as possible, especially species of high conservation or amenity value. Recommendations to be provided in the Tree Survey Report to mitigate impacts on trees should be followed.  Where trees are to be preserved in-situ, but are likely to be disturbed from works activities, protective fencing/hoarding should be carefully set up around the affected trees.

·        Disturbance of individuals of the protected shrub species Pavetta hongkongensis and tree Aquilaria sinensis of high conservation value should be avoided. A buffer to the dripline of each plant and no less than of at least 1m radius should be demarcated to prohibit disturbance.  Where loss of this species would be unavoidable, it is recommended that these plants may be transplanted to safe locations within the same habitat. Exact receptor sites should be determined by the horticulturist/ecologist on site at the time of the transplantation so that generally plants are moved as shortsmall short small a distance as possible to clear the works areas.  Specifications for transplantation should be included at the design stage.

Mitigation to minimise impacts from construction site run-off

·        Trench excavation works for the raw water mains near the stream courses should be carried out in the dry season, as far as practicable. Site runoff should be directed towards regularly cleaned and maintained silt traps and oil/grease separators to minimise the risk of sedimentation and pollution of river water. The silt and oil/grease separators should be appropriately designed for the local drainage and ground conditions (refer to Section 4 – Water Quality).

Mitigation to minimise general disturbance to wildlife

·        Noise mitigation measures through the use of quiet construction plant should be implemented to minimise disturbance to habitats adjacent to the works areas.


General good site practice

·         Placement of equipment or stockpile in designated works areas and access routes selected on existing disturbed land to minimise disturbance to natural habitats.

·         Construction activities should be restricted to works areas that should be clearly demarcated. The works areas should be reinstated after completion of the works.

·         Waste skips should be provided to collect general refuse and construction wastes. The wastes should be disposed of timely and properly off-site.

·         General drainage arrangements should include sediment and oil traps to collect and control construction site run-off.

·         Open burning on works sites is illegal, and should be strictly prohibited. Stove fires on works sites should also not be allowed. Temporary fire fighting equipment should be provided particularly in woodland areas.


Re-vegetation to reinstate works areas


·         As far as possible compensatory planting should use native plants of the same species that occur in the adjacent woodland habitat and have flowers/fruits attractive to wildlife. On-site compensatory planting should be conducted on at least a one to one basis.

Environmental Monitoring and Audit

5.6              The proper implementation of mitigation measures recommended above should be routinely audited during the construction phase of the designated and non-designated project elements.

5.7              Specific to the raw water mains installation at Pui O, aA methodology detailing the treatment of Pavetta hongkongensis and Aquilaria sinensis within the works areas in woodland should be formulated during the detailed design stage.


5.8              At the detailed design stage, individuals requiring transplantation and individuals requiring protection should be identified. Details should also include transplantation methodology and measures for the individuals to be protected ‘in-situ’. Survey work and reporting should be carried out by a suitably qualified ecologist/ horticulturist appointed by the Project Proponent. Suitable receptor sites should also be identified and prepared by the ecologist/ horticulturist prior to transplantation.

5.9              Following identification of individuals to be transplanted, transplantation procedures should be completed in advance of commencement of construction works.  The transplantation should be carried out by a suitably qualified ecologist/ horticulturist appointed by the Project Proponent. Measures to protect plants ‘in-situ’ should also be implemented prior to commencement of works.

5.10          Following any transplantation of Pavetta hongkongensis and Aquilaria sinensis individuals, regular monitoring of the trees and seedlings should be conducted to check on the health and condition of the plants. It is recommended that monitoring should cover the 12-month period following transplantation.  Monitoring should be conducted at least twice a month for the first four months after transplantation, and once a month for the remaining eight months. Monitoring should be conducted by a suitably qualified ecologist/horticulturalist appointed by the Project Proponent. If audit records indicate that the transplanted plants are not establishing properly, the Landscape Architect should recommend and undertake measures to rescue the plants.