S12_Summary of Outcomes

Table 12.1: Summary of Key Environmental Outcomes

Area/Issue	Environmental Outcomes
The Ngong Ping Drainage Improvement Project	Following serious flooding at the Po Lin Monastery, Ngong Ping Bus Terminus, Ngong Ping Village and areas in the vicinity of the Ngong Ping 360 Terminal in 2008, a study by the Drainage Services Department (DSD) identified that the flood protection level of the existing watercourses at the north of Po Lin Monastery, as well as the upstream and downstream of Ngong Ping 360 Terminal, is less than 1 in 10 years design return period and recommended a series of drainage improvement works. The project will include the following three main areas of improvement works: · Northern side of the Po Lin Monastery (Upstream Section): Interception Drain in the form of a new underground drainage pipe of 440m in length; · Northwest of the Po Lin Monastery near Lin Ping Drive (Midstream Section): Loop System comprising new underground box culvert of 223m in length; and · Northern side of the Ngong Ping 360 Terminal and Columbarium (Downstream Section): Flood Relief Drain comprising a new underground box drainage pipe of 198m in length.
Environmentally Friendly Design Recommended	While the selected alignment scheme offers several environmental advantages over other schemes considered during both the construction and operation phases. The adoption of the underground drainage design will reduce the permanent habitat loss to a few manholes only and these manholes have mostly been located within developed areas rather than natural habitats. Both the loop system and flood relief drain have been designed to avoid directly affecting the existing stream ecology and minimising the works in the natural stream section to only a small bank-side area for construction of Outfall B. Therefore, direct ecological impacts to the natural stream and associated riparian ecology would be almost completely eliminated during the construction stage. Given that streams in the area are hydro-dynamically linked to the Ngong Ping Stream in the Ngong Ping SSSI which is an important habitat for the endemic Romer’s Tree Frog as well as other fauna, this is considered a key environmentally friendly feature of the design. In respect of water quality, as the existing watercourse would remain untouched overall, with the exception of only five small areas for the inlets and outfalls, the potential construction phase water quality impacts would be minimised while still achieving the overall design objectives. From an ecological and landscape and visual impact, the design of the alignment has followed existing access roads and paths wherever possible to avoid impacts to natural habitats and also a trenchless construction method is proposed for two of the six works sections to minimise the open cut trench and the removal of habitats and vegetation. All works and stockpiling area locations have been carefully selected to avoid natural habitats and species of conservation interest as far as practical. This also minimises the amount of waste materials and the noise, dust and construction run-off that may result. Specifically, the location of Outfall B has been shifted southwards during the design development by about 13m such that it would not be located at a rocky cliff face and connect to the existing shallow pool area near the Columbarium. This has the advantage of making the Outfall B structure less visually prominent and allows a patch of protected orchids species in the cliff area to be avoided and retained. Stockpiling Area SA4 has also been relocated to the east of Works Section 6 to avoid some floral species of conservation interest. The proposed drainage scheme is overall further away from key sensitive receivers, thereby helping to reduce the magnitude of any air and noise impacts. There are no Declared Monuments or Graded Buildings within the Ngong Ping project area, and no areas with archaeological potential. While close to some heritage resources the drainage improvement works have been designed to avoid causing direct physical impacts on these heritage resources The pipeline alignment has been realigned to avoid the burial ground and graves near the Ngong Ping 360 Terminal, including a historical grave NP2.
Population and Environmentally Sensitive Areas Protected	With the adoption of the environmentally friendly design in the preferred option, the major environmental sensitive receivers will be protected. This preferred option is determined based on the comparison of the environmental benefits and dis-benefits of the various options and alternatives and has been selected on the basis that it minimises environmental impacts and presents overall environmental benefits over the other options and is considered the optimum scheme from an environmental perspective.
Air Quality	Potential dust impacts would be generated from excavation activities, material handling, wind erosion, spoil removal, material delivery, during the construction phase. Fugitive dust impacts would be controlled by the implementation of dust suppression measures as stipulated in the Air Pollution Control (Construction Dust) Regulation, good site practices and proposed mitigation measures. With the implementation of mitigation measures in the Air Pollution Control (Construction Dust) Regulation, proposed dust suppression measures including hourly watering of exposed area, together with good site practices, 1-hour, 24 hour and annual adverse residual impacts are predicted to be insignificant.
Noise	Without mitigation, given the close proximity of the sensitive receivers to the works, the noise levels would be anticipated to exceed the relevant criteria by up to about 18dB(A) at some NSRs. Mitigation measures are, therefore, recommended to reduce the noise levels to within the EIAO-TM noise criterion, including provision of quieter plants, silencers, noise barriers, enclosures and insulating fabric. After these mitigation measures are adopted, the noise levels at all but one representative NSR would meet the relevant criteria. Further mitigation has been proposed to install a temporary noise barrier of 2.5m in height or in a height which can provide sufficient screening of the vibrating hammer between the NSR and the open cut trench along the 44m segment in order to further mitigate noise impacts. However, one NSR, a village house very close the works, would subject to residual impacts of between 4-6dB(A). As such, all practicable noise mitigation measures will be exhausted to minimise the residual impacts, e.g. good site practices such as orientating the noisy plant away from the nearby NSRs, intermittent use of plant, proper fitting of silencers and mufflers on the construction equipment, avoidance of noisy construction works during the examination period etc. Residual impacts have been assessed and concluded to be temporary, reversible and unlikely to induce public health concern to the community and as such, are considered to be acceptable.
Water Quality	While direct impacts to the natural stream are minimised, the limited works required for the intake and outfalls will be undertaken in the dry season wherever possible. Other water quality impacts from construction activities would be in the form of construction run-off and this will be controlled by implementing the recommended mitigation measures, such as covering or reinstating exposed areas as soon as possible and confining stockpiling to designated areas, to minimise construction run-off and particularly on-site treatment of any contaminated wastewater prior to discharge. Adverse residual impacts would not be anticipated. No operational impacts are predicted and environmental resources are being protected by the mitigation measures.
Ecology	The potential ecological impacts have been substantially reduced by adoption of the terrestrial by-pass routing instead of direct widening and training of the natural Ngong Ping Stream. Permanent impacts have been further reduced by the adoption of and underground drainage system instead of open channel. Potential ecological impacts during the construction phase have been identified as temporary loss of mostly relatively low to moderate ecological value habitats although a small amount of woodland habitat will also be affected. A total of 0.47ha of vegetated area is predicted to be temporarily lost. Permanent losses have been minimised through the design of the drainage scheme and permanent losses of relatively low ecological value habitats are limited to 0.02ha. Landscape compensatory planting is recommended as mitigation for the loss of landscape and this will, also, serve the function as an enhancement to the tree and habitat loss as a result of drainage improvement works. Potential indirect impacts due to sedimentation and contamination will be controlled through a series of mitigation measures. Ecological mitigation measures have focused on the protection of species of conservation interest that may be affected. Two floral species of conservation interest in Works Area WA4 will be transplanted. Two floral species near WA4 will require suitable protection. Three aquatic faunal species that could be affected by the trench crossing section in Works Section 1 or as a result of works in WA4/Outfall B in Works Section 6 will be translocated prior to the works.
Landscape and Visual	The Project would be generally in accordance with the planning goals and objectives for the study areas but two areas are in potential conflict however, as follows: · Stockpile Area 1 (SA1); and · Works Section 6 The project has unavoidable Landscape and Visual Impacts resulting primarily from areas of excavation for trenches, construction pits for the trenchless excavation and the formation of intakes and outfalls, temporary works and stockpile sites. However, as the drainage design has minimized vegetation removal as much as possible by building along existing access roads, paths or development areas as much as possible, adopting trenchless construction where practicable and utilizing an underground pipeline scheme, no Significant Adverse Residual Impacts to Landscape Resources, Landscape Character or VSRs are generated by the Project at any stage. A total of 612 existing trees have been surveyed covering the Project Area. Some 155 trees will be affected by the proposed works and 155 are proposed to be felled of which 65 are dead trees. Those trees found to be directly conflict with the construction works which cannot be retained have not been considered suitable for transplantation. None of these are Registered Old and Valuable Trees. The compensatory planting regime would include planting of a minimum of 89 heavy standard trees at a compensation level of 1:1, in addition to 3711m²of hydroseeding.
Cultural Heritage	The archaeology assessment did not identify any areas of archaeological potential and no impacts are predicted. There are no Declared Monuments or graded Buildings that will be affected by the project. However, the Built Heritage Impact Assessment identified six built heritage resources in the form of village houses that will require mitigation. Mitigation in the form of a condition survey will be required for three of the resources (NP-10, NP-11 and NP-19) and the condition survey will recommended if vibration monitoring is required. A buffer zone of a minimum of 5 metres in size should be marked out for the following resources which are close to either a works area or excavation area, namely NP-19, NP-20, NP-21 and NP-26. The construction and operation of the drainage improvement works will not cause any insurmountable adverse impacts if the above mitigation measures are implemented properly.
Waste Management Implications	Construction waste arisings have been identified based on the proposed construction activities and would comprise C&D materials (including excavated materials, materials from demolition works and site formation), general refuse from workforce, chemical waste from maintenance of construction plant and equipment and sewage from on-site staff and workers. Provided that the identified waste arisings are to be handled, transported and disposed of using approved methods and the recommended good site practices are to be followed, adverse environmental impacts would not be expected during the construction phase. The types of waste generated during the operation of the project would be limited to inert materials (e.g. sand, boulder, etc) and non-inert materials (e.g. rubbish, tree debris, etc) removed from the maintenance of the drainage system will but as the quantities will be negligible, adverse impacts would not be expected during the operational phase of the project.

Area/Issue

Environmental Outcomes

The Ngong Ping Drainage Improvement Project

Following serious flooding at the Po Lin Monastery, Ngong Ping Bus Terminus, Ngong Ping Village and areas in the vicinity of the Ngong Ping 360 Terminal in 2008, a study by the Drainage Services Department (DSD) identified that the flood protection level of the existing watercourses at the north of Po Lin Monastery, as well as the upstream and downstream of Ngong Ping 360 Terminal, is less than 1 in 10 years design return period and recommended a series of drainage improvement works. The project will include the following three main areas of improvement works:

· Northern side of the Po Lin Monastery (Upstream Section): Interception Drain in the form of a new underground drainage pipe of 440m in length;

· Northwest of the Po Lin Monastery near Lin Ping Drive (Midstream Section): Loop System comprising new underground box culvert of 223m in length; and

· Northern side of the Ngong Ping 360 Terminal and Columbarium (Downstream Section): Flood Relief Drain comprising a new underground box drainage pipe of 198m in length.

Environmentally Friendly Design Recommended

While the selected alignment scheme offers several environmental advantages over other schemes considered during both the construction and operation phases. The adoption of the underground drainage design will reduce the permanent habitat loss to a few manholes only and these manholes have mostly been located within developed areas rather than natural habitats.

Both the loop system and flood relief drain have been designed to avoid directly affecting the existing stream ecology and minimising the works in the natural stream section to only a small bank-side area for construction of Outfall B. Therefore, direct ecological impacts to the natural stream and associated riparian ecology would be almost completely eliminated during the construction stage. Given that streams in the area are hydro-dynamically linked to the Ngong Ping Stream in the Ngong Ping SSSI which is an important habitat for the endemic Romer’s Tree Frog as well as other fauna, this is considered a key environmentally friendly feature of the design.

In respect of water quality, as the existing watercourse would remain untouched overall, with the exception of only five small areas for the inlets and outfalls, the potential construction phase water quality impacts would be minimised while still achieving the overall design objectives.

From an ecological and landscape and visual impact, the design of the alignment has followed existing access roads and paths wherever possible to avoid impacts to natural habitats and also a trenchless construction method is proposed for two of the six works sections to minimise the open cut trench and the removal of habitats and vegetation. All works and stockpiling area locations have been carefully selected to avoid natural habitats and species of conservation interest as far as practical. This also minimises the amount of waste materials and the noise, dust and construction run-off that may result. Specifically, the location of Outfall B has been shifted southwards during the design development by about 13m such that it would not be located at a rocky cliff face and connect to the existing shallow pool area near the Columbarium. This has the advantage of making the Outfall B structure less visually prominent and allows a patch of protected orchids species in the cliff area to be avoided and retained. Stockpiling Area SA4 has also been relocated to the east of Works Section 6 to avoid some floral species of conservation interest.

The proposed drainage scheme is overall further away from key sensitive receivers, thereby helping to reduce the magnitude of any air and noise impacts.

There are no Declared Monuments or Graded Buildings within the Ngong Ping project area, and no areas with archaeological potential. While close to some heritage resources the drainage improvement works have been designed to avoid causing direct physical impacts on these heritage resources The pipeline alignment has been realigned to avoid the burial ground and graves near the Ngong Ping 360 Terminal, including a historical grave NP2.

Population and Environmentally Sensitive Areas Protected

With the adoption of the environmentally friendly design in the preferred option, the major environmental sensitive receivers will be protected. This preferred option is determined based on the comparison of the environmental benefits and dis-benefits of the various options and alternatives and has been selected on the basis that it minimises environmental impacts and presents overall environmental benefits over the other options and is considered the optimum scheme from an environmental perspective.

Air Quality

Potential dust impacts would be generated from excavation activities, material handling, wind erosion, spoil removal, material delivery, during the construction phase. Fugitive dust impacts would be controlled by the implementation of dust suppression measures as stipulated in the Air Pollution Control (Construction Dust) Regulation, good site practices and proposed mitigation measures. With the implementation of mitigation measures in the Air Pollution Control (Construction Dust) Regulation, proposed dust suppression measures including hourly watering of exposed area, together with good site practices, 1-hour, 24 hour and annual adverse residual impacts are predicted to be insignificant.

Noise

Without mitigation, given the close proximity of the sensitive receivers to the works, the noise levels would be anticipated to exceed the relevant criteria by up to about 18dB(A) at some NSRs. Mitigation measures are, therefore, recommended to reduce the noise levels to within the EIAO-TM noise criterion, including provision of quieter plants, silencers, noise barriers, enclosures and insulating fabric. After these mitigation measures are adopted, the noise levels at all but one representative NSR would meet the relevant criteria. Further mitigation has been proposed to install a temporary noise barrier of 2.5m in height or in a height which can provide sufficient screening of the vibrating hammer between the NSR and the open cut trench along the 44m segment in order to further mitigate noise impacts. However, one NSR, a village house very close the works, would subject to residual impacts of between 4-6dB(A). As such, all practicable noise mitigation measures will be exhausted to minimise the residual impacts, e.g. good site practices such as orientating the noisy plant away from the nearby NSRs, intermittent use of plant, proper fitting of silencers and mufflers on the construction equipment, avoidance of noisy construction works during the examination period etc. Residual impacts have been assessed and concluded to be temporary, reversible and unlikely to induce public health concern to the community and as such, are considered to be acceptable.

Water Quality

While direct impacts to the natural stream are minimised, the limited works required for the intake and outfalls will be undertaken in the dry season wherever possible. Other water quality impacts from construction activities would be in the form of construction run-off and this will be controlled by implementing the recommended mitigation measures, such as covering or reinstating exposed areas as soon as possible and confining stockpiling to designated areas, to minimise construction run-off and particularly on-site treatment of any contaminated wastewater prior to discharge.

Adverse residual impacts would not be anticipated. No operational impacts are predicted and environmental resources are being protected by the mitigation measures.

Ecology

The potential ecological impacts have been substantially reduced by adoption of the terrestrial by-pass routing instead of direct widening and training of the natural Ngong Ping Stream. Permanent impacts have been further reduced by the adoption of and underground drainage system instead of open channel. Potential ecological impacts during the construction phase have been identified as temporary loss of mostly relatively low to moderate ecological value habitats although a small amount of woodland habitat will also be affected. A total of 0.47ha of vegetated area is predicted to be temporarily lost. Permanent losses have been minimised through the design of the drainage scheme and permanent losses of relatively low ecological value habitats are limited to 0.02ha. Landscape compensatory planting is recommended as mitigation for the loss of landscape and this will, also, serve the function as an enhancement to the tree and habitat loss as a result of drainage improvement works.

Potential indirect impacts due to sedimentation and contamination will be controlled through a series of mitigation measures.

Ecological mitigation measures have focused on the protection of species of conservation interest that may be affected. Two floral species of conservation interest in Works Area WA4 will be transplanted. Two floral species near WA4 will require suitable protection. Three aquatic faunal species that could be affected by the trench crossing section in Works Section 1 or as a result of works in WA4/Outfall B in Works Section 6 will be translocated prior to the works.

Landscape and Visual

The Project would be generally in accordance with the planning goals and objectives for the study areas but two areas are in potential conflict however, as follows:

· Stockpile Area 1 (SA1); and

· Works Section 6

The project has unavoidable Landscape and Visual Impacts resulting primarily from areas of excavation for trenches, construction pits for the trenchless excavation and the formation of intakes and outfalls, temporary works and stockpile sites. However, as the drainage design has minimized vegetation removal as much as possible by building along existing access roads, paths or development areas as much as possible, adopting trenchless construction where practicable and utilizing an underground pipeline scheme, no Significant Adverse Residual Impacts to Landscape Resources, Landscape Character or VSRs are generated by the Project at any stage.

A total of 612 existing trees have been surveyed covering the Project Area. Some 155 trees will be affected by the proposed works and 155 are proposed to be felled of which 65 are dead trees. Those trees found to be directly conflict with the construction works which cannot be retained have not been considered suitable for transplantation. None of these are Registered Old and Valuable Trees. The compensatory planting regime would include planting of a minimum of 89 heavy standard trees at a compensation level of 1:1, in addition to 3711m²of hydroseeding.

Cultural Heritage

The archaeology assessment did not identify any areas of archaeological potential and no impacts are predicted.

There are no Declared Monuments or graded Buildings that will be affected by the project. However, the Built Heritage Impact Assessment identified six built heritage resources in the form of village houses that will require mitigation. Mitigation in the form of a condition survey will be required for three of the resources (NP-10, NP-11 and NP-19) and the condition survey will recommended if vibration monitoring is required. A buffer zone of a minimum of 5 metres in size should be marked out for the following resources which are close to either a works area or excavation area, namely NP-19, NP-20, NP-21 and NP-26. The construction and operation of the drainage improvement works will not cause any insurmountable adverse impacts if the above mitigation measures are implemented properly.

Waste Management Implications

Construction waste arisings have been identified based on the proposed construction activities and would comprise C&D materials (including excavated materials, materials from demolition works and site formation), general refuse from workforce, chemical waste from maintenance of construction plant and equipment and sewage from on-site staff and workers. Provided that the identified waste arisings are to be handled, transported and disposed of using approved methods and the recommended good site practices are to be followed, adverse environmental impacts would not be expected during the construction phase.

The types of waste generated during the operation of the project would be limited to inert materials (e.g. sand, boulder, etc) and non-inert materials (e.g. rubbish, tree debris, etc) removed from the maintenance of the drainage system will but as the quantities will be negligible, adverse impacts would not be expected during the operational phase of the project.

12 summary of outcomes