Ecological Enhancement
It is our policy to incorporate environmentally friendly features into new or upgrading projects wherever possible. The features provide greenery in the countryside, restore or compensate for disturbed habitats and preserve valuable freshwater ecosystems. As a result of our commitment and actions, works in the past decade have cumulated into large tracts of vegetated river banks, preserved meanders, wetland features and mangrove habitats.

Ecological and landscape improvement measures are usually derived from EIAs of new projects, while we also advocate good ecological practices amongst our engineers through circulation of guidance notes.


Our effort has included:
Wetland Creation
Habitat preservation and enrichment
Harmonising new works with the surrounding

1.Wetland Creation
2 major river training projects namely Yuen Long Bypass Floodway, and Construction of San Tin Eastern Main Drainage Channel are notable examples of habitat creation. Works were in progress in 2003. These projects will respectively create 7.9 and 3.7 hectares of wetland habitats.

Yuen Long Bypass Floodway
The Yuen Long Bypass floodway is a new channel constructed to divert storm water from south east of Yuen Long into Kam Tin River to reduce flood risk in Yuen Long town centre and other lower lying areas.


To promote biodiversity, this flood defence works will incorporate two major ecological features V a created wetland and in-channel shallow ponds.

Created Wetland
Several fallow fish ponds in the North of the confluence of the Bypass Floodway and Kam Tin River will be enriched to become 7.9 ha of wetland, comprising 6.4 ha of marshes of varying depths and 1.5 ha of reedbed.


Differential depths sustain a diversity of ecological niches. The deeper marsh provides habitat for large fishes and the associated bird community, while the shallower submerged marsh will be ideal to become foraging grounds for wading birds. Planting of marsh vegetation will jump start the plant establishment process which will lead to colonisation of the wetland by insects, aquatic invertebrates, fishes, amphibians, reptiles and birds. The biodiversity of the created wetland will thus be a quantum leap from that of the original fishponds.

The reed bed will take the flow of the channel over a mass of artificial boulders that acts as a biofilter to break down organic matter. The reed bed further serves as an effective purifier that assimilates nutrients. Passage of flow over the boulder area and reed bed gives a steady supply of clean water to the marshes.

   

Two bat roosts will also be constructed in the wetland to encourage habitation by this type of flying mammal.

Ecologically important animal life attracted to the YLBF wetland will include damselflies, spotted narrow-mouth frog (Kalophrynus pleurostigma), bats such as Japanese Pipistrelle, birds both resident and visitors such as egrets, pond heron, Stints, and the endangered Black-faced Spoonbill.

Shallow pond feature
To promote and sustain stream life, 350 m of channel bed or about 1.2 ha of the floodway will take the form of shallow ponds that are purposely engineered to provide habitat for freshwater fish, amphibians and water birds. It is the first of its kind in Hong Kong, of a man-made waterway that serves a flood defence purpose while specially built to become a vibrant freshwater ecosystem.


Landscaping
Landscape quality of YLBF is enhanced with establishment of grass on the channel base and the inner embankment on grassing concrete, giving a total of 6.8ha of greenery. Furthermore, about 3,000 trees will be planted along the channel to compensate for the loss of 400. Grass cover and trees have tremendous environmental benefits as they reduce heat retention, provide foliage, shades and landscape features to the water edge, trap dustfall and increase habitat diversity and amenity value.

Success of this project will go a long way in providing valuable reference for future channel engineering work to coexist with nature conservation.

Wetland in San Tin
The San Tin Eastern Main Drainage Channel project that aims to alleviate flooding problems in the low-lying areas at the east of San Tin and Ki Lun Tsuen of Yuen Long has incorporated environmental mitigation measures including compensatory planting, wetland creation and landscape works. It includes establishment of 3.7 ha of wetland habitat comprising ponds and reedbed alongside the channel. Additionally, to facilitate vegetation development and animal foraging and breeding, the embankment will not be lined at the lower reaches of the San Tin Eastern Main Channel.

Another project in the area, the flood control works to protect San Tin, has necessitated the construction of embankments, flood pumping station and floodwater storage ponds. As the landscape and ecological mitigation measure, the San Tin Created Wetland was developed from an abandoned fishpond at the junction of San Tin Tsuen Road and Castle Peak Road, Shek Wu Wai, San Tin, Yuen Long.



Wetland plants such as water lilies, sedges and Lugwigia were successful introduced in the submerged area and water margin. The open water and sides now support a diversity of plants, freshwater fishes, amphibians and dragonflies.

44 species of birds including Grey Heron, Kingfishers, sandpipers, waterhen, and Oriental Reed Warbler have been sighted since creation of the wetland. They included resident species, winter visitors and passage migrants.


2.Habitat preservation and enrichment

Much attention is given to leaving shelter and foraging grounds for wildlife in our works to reintegrate the channel into the natural environment. Our endeavours are shown below.





3.Harmonising new works with the surrounding
In one of our latest projects, the Ngong Ping Sewage Treatment Works which has now started construction, the landscape and social setting was studied in detail to pave way for a meticulously designed architecture that blends seamlessly into the local area.

This sewage treatment plant serves the Po Lin Monastery, Ngong Ping Village, and the future theme village associated with the Tung Chung Cable Car ride. In the design, most of the major structures of the sewage treatment works will be underground or covered. Generous planting of native woodland trees and shrubs is specified in the landscape plan to compensate for loss of any existing vegetation, to screen sensitive views and to act as an environmental benefit for local residents, workers, and visitors.

Furthermore, the choice of architectural design and finishing of the superstructures will adopt traditional Chinese elements and colours interpreted in a contemporary manner to make the sewage works inconspicuous and fit smoothly into the landscape character of the area.








The Ngong Ping STW will also be Hong Kong's first tertiary treatment plant that includes due media filter and effluent disinfection by ultraviolet light. Effluent will be reused for toilet flushing and thus help conserve freshwater resources. Giving due regard to the fragile ecology of the Ngong Ping highland area, the project includes a 5.7-km pipeline system to discharge surplus effluent to sea at Tung Wan, Lantau.