Contract No. NL/2017/03
Tung Chung New Town Extension – Reclamation and Advance Works
Eco-shoreline Implementation Plan
September 2020
TABLE OF CONTENTS
Page
5. detailed management Arrangments
5.2. Mangrove and Rocky Eco-shoreline
6. Monitoring Programme with Indicators for success
APPENDICES
Appendix A – Implementation Programme for Eco-shoreline
Appendix B – Implementation Schedule for Eco-shoreline
1.1.1 AECOM Asia Co Ltd has been commissioned by the Civil Engineering and Development Department (CEDD) to undertake Agreement No. CE 69/2015 (CE) – Tung Chung New Town Extension (East) – Design and Construction. The Agreement commenced on 16 June 2016 and is scheduled to be completed in June 2027.
1.1.2 The reclamation, site formation, engineering infrastructure and associated works to support developments of both Tung Chung East (TCE) and Tung Chung West (TCW) are funded by PWP Item "7786CL - Tung Chung New Town Extension". The Technical Feasibility Statement for 7786CL was approved in September 2014. 7786CL is to be delivered by two consultancy agreements namely, Tung Chung New Town Extension (East) - Design and Construction (this Assignment) and Tung Chung New Town Extension (West) - Design and Construction (Agreement No. CE 70/2015(CE)).
1.1.3 The Project of this Assignment (the Project) includes reclamation, site formation and engineering infrastructure works (including construction of Road P1) for the developments of TCE, provision of salt water supply to TCNT and SHW topside and infrastructure works in Tung Chung Area 58 in the existing TCNT. The scope of the Project comprises the following principal works components:
a) Works in TCE
(i) Reclamation of about 120 hectares of seabed abutting the coastal area between Tung Chung Phase 3A and Tai Ho Bay Inlet and associated site formation works for the proposed developments;
(ii) Engineering infrastructure works including roads, drainage, sewerage including sewage pumping stations, and waterworks to support the proposed developments;
(iii) Provision of a marina;
(iv) Construction of a salt water pumping station for flushing use in TCNT, TCE, TCW and SHW topside;
(v) Landscaping, streetscaping and ancillary works; and
(vi) Provision of environmental mitigation measures for the works mentioned in (i) to (vi) above;
b) Works in the existing TCNT or SHW
(i) Construction of a Fresh Water Service Reservoir (FWSR) near Chek Lap Kok New Village or at Siu Ho Wan for TCE and TCW;
(ii) Construction of a Salt Water Service Reservoir (SWSR) near Chek Lap Kok New Village for flushing use in TCNT, TCE, TCW and SHW topside;
(iii) Site formation works including natural terrain hazards mitigation measures for the works mentioned in (i) and (ii) above;
(iv) Waterworks for salt water supply for toilet flushing in SHW topside; and
(v) Engineering infrastructure works including roads, drainage, sewerage and waterworks to support the land allocation at Area 58 of the existing TCNT.
c) Works related to Road P1
(i) Reclamation of about 9 hectares of seabed for Road P1 (section between TCE and Tai Ho);
(ii) Construction of Road P1 with cycle track (section between TCE and Tai Ho) and associated engineering infrastructure works including drainage, sewerage and waterworks;
(iii) Site formation works for a cycle park of about 2 hectares near Tai Ho Interchange;
(iv) Improvement works to existing Tung Chung Waterfront Road and Ying Hei Road, including construction of noise barriers and footbridges, resurfacing of road pavement, etc., for upgrading them to a primary distributor as part of Road P1;
(v) Construction of an elevated interchange near Tai Ho connecting Road P1 to NLH and Cheung Tung Road (Tai Ho Interchange);
(vi) Landscaping, streetscaping works and ancillary works; and
(vii) Provision of environmental mitigation measures for the works mentioned in (i) to (vi) above.
1.1.4 Recognising the limited ecological value of standard artificial seawall design, the Project Environmental Impact Assessment (EIA) Report (CEDD, 2015) recommended that ecological enhancement measures are considered in the seawall design for the TCE Potential Development Area (PDA) and Road P1 (Tung Chung - Tai Ho Section) Extension reclamation. This would provide mitigation for marine ecological impacts resulting from the Project, which include the permanent loss of 145 ha of marine waters/seabed (considered a minor to moderate scale impact, Diagram 1.1). Ecologically enhanced seawalls could partially compensate this impact by providing habitat for intertidal and subtidal marine communities.
Diagram 1.1 – Extent of Permanent Seabed Habitat Loss (CEDD, 2015)
(i) the form of eco-shoreline to be adopted for the artificial seawall along the reclamation boundary at Tung Chung East;
(ii) a robust and innovative eco-shoreline design with clear objectives of enhancing its ecological, landscape, visual and other functions;
(iii) an implementation programme;
(iv) detailed management arrangements; and
(v) a monitoring programme with indicators for success.
· Vertical Eco-shoreline: June 2020
· Rocky Eco-shoreline: August 2021
· Mangrove Eco-shoreline: end May 2021
2.1.2 Eco-shoreline is to provide ecological functions to mitigate the loss of general marine habitat, while the function of coastal and shoreline protection should be provided by seawall structure. Elements of eco-shoreline such as mangroves, mudflat, oyster basket and bio-blocks will be installed/planted on top of seawall structure. The seawall structure was designed in accordance with Port Works Design Manual.
Diagram 2.1 – Layout Plan for Eco-shoreline
Note: Location of box culverts, District Cooling System outfall and intake are indicative.
Diagram 2.2 – Typical Section of Mangrove Eco-shoreline
Diagram 2.3 – Typical Section of Rocky Eco-shoreline
Diagram 2.4 – Typical Section of Vertical Eco-shoreline
Design Concept
Diagram 3.1 – Design of Mangrove Eco-shoreline
Planting
· Native species to be used in the planting include Acanthus ilicifolius, Aegiceras corniculatum, Avicennia marina, Bruguiera gymnorhiza, Lumnitzera racemosa, and Kandelia obovata.
· Where possible, seeds/droppers of these species should be collected from nearby established mangrove stands (e.g., Tung Chung Bay and/or Tai O), as using locally sourced seeds (as opposed to using nursery-grown plants from abroad) will maintain the integrity of local genetic stock diversity. Local seed stocks are also potentially better adapted to local conditions which may also be of importance for succession of locally-adapted secondary species.
· Collected seeds/droppers should be moved to a nursery area for establishment. Developing a small nursery close to mangrove planting sites is an established method for germinating and cultivating collected seeds/droppers. Typically, nurseries require the following:
- Size: Experience from overseas (Hoang, V.T., and Pham, T.T. (2010), Management of Natural Resources in the Coastal Zone of Soc Trang Province: Mangrove Nursery Manual. GTZ: 44p ) suggests around 325m2 flat area is needed to grow 10,000 seedlings per year (allowing for 20% mortality), together with 100-200m2 general working area.
- Water Supply: mangrove seeds and seedlings need require daily watering, so an adequate water supply is needed. Although brackish or salt water can be used, germination success and growth rates for most species are much higher if freshwater is used
- Drainage: adequate drainage is required to prevent flooding and washing out of seeds/seedlings.
· Established mangrove seedlings will be planted out in the mangrove/mudflat eco-shoreline at approximately 1 m intervals.
Viewing of Eco-shoreline
Design Concept
· Natural stone is more difficult and expensive to source and dress to the dimensions needed.
· Using concrete provides an opportunity to cast holes, ledges and other surface structures that will increase the habitat value of the blocks.
· Some concrete solutions with lower pH and other characteristics have been designed to minimise toxicity and maximise ecologically usable surface.
Diagram 3.2 – Design of Rocky Eco-shoreline
Diagram 3.3 – Detail of Bio-Block with Configuration and Micro-pools to Create Rockpools
Viewing of Eco-shoreline
Design Concept
· Small (e.g. 5 – 10 cm in diameter and 15 cm deep) holes will be drilled in the seawall at a 45 degree angle (so they retain water at low tide) to provide refuge for crabs, fish and other larger fauna. The holes will cover inter-tidal and sub-tidal areas of the seawall, and be provided at 50 cm – 100 cm intervals.
· Larger cavities (e.g. 80 cm high, 40 cm wide and deep) pre-cast into the concrete should be included above the high tide level every 10 m – 30 m. These will provide platforms for wetland birds (e.g. White Wagtail, Motacilla Alba) to hunt and rest.
· Eco-pots made of clay with internal dimension of 300mm (length) x 150mm (width) x 300mm (depth) and pot thickness of 40mm shall be attached to the vertical eco-shoreline at 10m intervals with the top of the eco-pot at +1.3mPD. This will provide a refuge for marine organism by retaining water during low tide.
Public Information
Introduction
Diagram 3.4 – Oyster Basket filled with Oyster Shells
· Mesh size of the oyster basket is about 5 cm.
· Dimension of oyster basket: 300 mm x 300 mm x 700 mm
· Oyster baskets will be made of stainless steel wire.
· Baskets can be filled to approximately 60% capacity with oyster shells.
Item |
Description |
Maintenance Agent |
1 |
Eco-features, including bird resting area, eco-surface pattern, eco-drillhole and eco-pot |
Port Works Division/ CEDD |
Table 5.1 – Maintenance Agents of Vertical Eco-shoreline
Item |
Description |
Maintenance Agent |
1 |
Planter for Mangrove |
Port Works Division/ CEDD |
2 |
Planter for Bio-blocks |
Port Works Division/ CEDD |
3 |
Oyster Basket |
Port Works Division/ CEDD |
Table 5.2 – Maintenance Agents of Mangrove and Rocky Eco-shoreline
Diagram 6.2 – Location of Proposed Reference Monitoring Locations
Diagram 6.3 – Photos of Proposed Reference Monitoring Locations
Table 6.1 – Mangrove Eco-shoreline Monitoring Methodology
Parameter |
Methodology |
No. of Sample |
Details |
Avifauna |
Point count |
1 |
Single point count undertaken at each sampling point. Surveys undertaken for a period of 15min covering all visible areas (i.e., 360º) at a radius of 100m from the survey point. Record made of avifauna species richness and abundance in different habitats (i.e., mangrove, mudflat, open water, seawall, landscape promenade) as well as any notable behaviour (hunting, roosting, nesting). |
Epifauna |
Transect |
3 |
1m2 quadrat surveyed at three points (high, medium and low shore) along each transect. Species richness and abundance/frequency recorded. Diversity index and evenness index should be calculated. |
Infauna |
Transect |
3 |
0.25m2 quadrat surveyed at three points (high, medium and low shore) along each transect. The top 0.1m mudlfat layer within the quadrat will be collected and screened through 0.5mm mesh size sieve. Fauna sorted will be identified and counted. |
Vegetation |
Transect |
3 |
2m2 quadrat surveyed at three points (high, medium and low shore) along each transect. The following information about each plant within the quadrat will be recorded: species, height, number of leaves and health (signs of chlorosis/necrosis). |
Fixed Point Sample |
3 |
General mangrove health (% mortality) at each location will be recorded, with fixed point photographs taken for easy comparison of mangrove health/ |
|
Mudflat Properties |
Core Sample |
3 |
2-3cm diameter core sample taken at high, middle and low shore. Particle size, organic content, C, N, pH and salinity, should be measured. |
Mudflat Level |
Fixed gauge at seaward and landward side of the mangrove area |
3 |
Measure top level of mudflat. |
Spot sample |
3 |
Dissolved oxygen (DO), dissolved oxygen saturation (DO%), temperature, turbidity, salinity, pH and suspended solids (SS), should be measured. |
Rocky Eco-shoreline
Table 6.2 – Rocky Eco-shoreline Monitoring Methodology
Parameter |
Methodology |
No. of Sample |
Details |
Avifauna |
Point count |
1 |
Single point count undertaken at each sampling point. Surveys undertaken for a period of 15min covering all visible areas (i.e., 360º) at a radius of 100m from the survey point. Record made of avifauna species richness and abundance in different habitats (i.e., mangrove, mudflat, open water, seawall, landscape promenade) as well as any notable behaviour (hunting, roosting, nesting). |
Epifauna |
Transect |
3 |
1m2 quadrat surveyed at three points (high, medium and low shore) along each transect. Species richness and abundance/frequency recorded. Diversity index and evenness index should be calculated. |
Water Quality |
Spot sample |
3 |
Dissolved oxygen (DO), dissolved oxygen saturation (DO%), temperature, turbidity, salinity, pH and suspended solids (SS), should be measured. |
Table 6.3 – Vertical Eco-shoreline Monitoring Methodology
Parameter |
Methodology |
No. of Sample |
Details |
Avifauna |
Point count |
1 |
Single point count undertaken at each sampling point. Surveys undertaken for a period of 15min covering all visible areas (i.e., 360º) at a radius of 100m from the survey point. Record made of avifauna species richness and abundance in different habitats (i.e., mangrove, mudflat, open water, seawall, landscape promenade) as well as any notable behaviour (hunting, roosting, nesting). |
Epifauna |
Transect |
3 |
1m2 quadrat surveyed at three points (high, medium and low shore) along each transect. Species richness and abundance/frequency recorded. Diversity index and evenness index should be calculated. |
Water Quality |
Spot sample |
3 |
Dissolved oxygen (DO), dissolved oxygen saturation (DO%), temperature, turbidity, salinity, pH and suspended solids (SS), should be measured. |
Ichthyoplankton and Juvenile Fish Monitoring
Table 6.4 – Ichthyoplankton and Juvenile Fish Monitoring Methodology
Parameter |
Methodology |
No. of Sample |
Details |
Ichthyoplankton |
Plankton net |
1 |
Sampling undertaken with one pair of bongo net with 0.5mm mesh size, towed at a speed of around 1 - 2 knots against the flow. Samples to be sorted in the laboratory, with all fish larvae to be identified and counted, and diversity/ eveness should be calculated. |
Juvenile Fish |
Purse Seine |
3 |
Sampling undertaken with purse seine nets and cage traps with 2cm mesh size: - Purse seine survey to be completed in around 20 minutes. - Five baited cage traps to be deployed overnight at each sampling location The catches were identified to species level as far as practicable and the species composition, abundance, size and biomass in weight were measured, and diversity/ evenness should be calculated. |
Reference Site Monitoring
Mangrove, Rocky and Vertical Eco-shoreline
Ichthyoplankton and Juvenile Fish Monitoring
· Description of monitoring works undertaken in the Reporting period
· Presentation of the results of monitoring works
· Comparison of monitoring results with reference sites
· Comparison of monitoring results with previous monitoring periods
· Analysis of monitoring data. For large data sets where samples are not independent (due to proximity of the monitoring sites), it is recommended multivariate analysis is adopted for data analysis. Non-metric Multidimensional Scaling can be used to identify trends in biological data across different sampling locations, and correlate these with environmental data.
· Identification of management and maintenance issues
· Identification of opportunities for further enhancement works
|
Appendix A |
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Appendix B |