7.1.1 The Contractor shall be responsible for the detailed design, implementation and monitoring of recommended mitigation measures in order to minimise ecological impacts during construction of the DBL.
7.2.1 Monitoring of effects of the construction works on wildlife will be necessary in order to detect and take action to reduce any unacceptable impacts. The implementation of mitigation measures should be monitored to ensure that objectives and specifications are met.
7.2.2 The proposed programme of ecological monitoring is described in Table 7.1. Monitoring for the proposed wetland compensation area is described in detail in Table 7.2. For reference, the mitigation measures are summarised in the paragraphs that follow.
Table 7.1 Summary of Ecological Mitigation
|
Impact |
Mitigation |
|
Pond Loss |
0.73 ha. Wetland Compensation Area (WCA) at Ngau Hom Shek. |
|
Tree loss |
8.7 ha. roadside plantings (see landscape chapter for further details) |
|
Loss of Ngau Hom Shek egretry |
Clearance of egretry before breeding season commences; Transplanting bamboo to WCA |
|
Habitat fragmentation |
Wildlife underpasses on dry shoulders associated with stream culverts |
|
Disturbance |
Noise barriers (see noise chapter for further details) |
|
Water quality degradation |
See water chapter for further details |
Table 7.2 Ecological Monitoring
|
Location |
Objective |
Frequency/timing |
|
Egretry at Ngau Hom Shek |
To check that egretry has been cleared in advance of the breeding season. This will ensure that nesting egrets are not disturbed during nesting but will seek alternative sites. |
Once before breeding season commences (before March) |
|
Proposed wetland compensation area (WCA) above Ngau Hom Shek |
To check on the construction and planting of the created wetland |
Weekly or as required during construction. |
|
Proposed wetland compensation area (WCA) above Ngau Hom Shek |
To check on the transplantation of bamboo from existing egretry to WCA |
As required during transplantation. Quarterly during first year of establishment. |
|
Proposed WCA above Ngau Hom Shek |
To monitor the general habitat conditions and colonisation and use of the area by wildlife, with particular reference to birds of conservation concern (herons and egrets) and their prey items |
Throughout year as directed for each group immediately following construction for two years. |
|
Various |
To check correct installation of wildlife underpasses |
As required during installation.
|
7.2.3 The objectives of the proposed 0.73ha. wetland compensation area (WCA) above Ngau Hom Shek is to compensate for the loss of abandoned ponds and to provide feeding opportunities for wildlife (e.g. ardeids) which have been recorded in small numbers in the area.
7.2.4 In order to ensure that the wetland compensation area meets these objectives, ecological monitoring will be required during construction and planting and during the first two years of after establishment.
7.2.5 Monitoring during construction and early establishment should be undertaken to ensure that the contractor:
This will involve weekly visits during active construction and other visits as required.
7.2.6 Monitoring of habitat conditions and colonisation by flora and fauna during the first two years after completion of construction is given in Table 7.3 below:
Table 7.3 Monitoring of Wetland Compensation Area
|
Group or Parameter |
Method |
Frequency/timing |
|
Water level |
Fixed yardstick |
Quarterly |
|
Water quality: BOD and dissolved oxygen |
Collect sample for BOD measurement in laboratory, DO probe in field. |
Quarterly |
|
Flora |
Recording of % cover for each species within a fixed 1m wide belt transect starting on dry bank and ending in open water. The transect is to be permanently marked. Vegetation height to be measured and photographs taken. |
Wet season (June) and dry season (December). |
|
Birds |
Fixed point counts at dawn on 2 successive days each quarter |
Wet season (breeding birds); autumn migration period; dry season (wintering birds) and spring migration. |
|
Benthos |
No.5 of 50mm cores at 100mm depth. Washed through 5mm sieve. Specimen preserved in formalin and sorted and identified. Numerical abundance and dry biomass to be determined. |
Wet season and dry season |
|
Pelagic fauna – fish and invertebrates |
Netting for standard period with standard net. Samples to be identified and numerical abundance and biomass to be determined |
Wet season and dry season |
|
Amphibians |
Survey of breeding amphibians using nocturnal torch-light searches and listening for calls. |
May following rain |
7.3.1 The main objective of the proposed wetland compensation area is to provide feeding opportunities for wildlife (notably ardeids) which have been recorded in small numbers in the area. Monitoring will reveal the level of ardeid use. This proposed wetland is expected to support a small number of Little Egret and Chinese Heron associated with the affected wetland areas. No specific trigger levels for ardeid use are recommended because of the low level of use expected and because immediate action is not appropriate for the long term process of wetland creation and management. If no ardeids are recorded or other unexpected findings made, possible causes should be considered and appropriate changes to the management made. This issue will be considered in the Habitat Creation and Management Plan which is to be prepared at the detailed design stage.