4. Fisheries Impact

Introduction

4.1 This section presents the fisheries impact assessment for the Project within the study area. The fisheries impact assessment includes the following tasks:

l Review of relevant legislation, standards and guidelines;

l Baseline fisheries conditions;

l Assessment of the existing aquaculture activities and fisheries resources;

l Identification, prediction and evaluation of fisheries impacts;

l Recommendation on required mitigation measures; and

l Environmental monitoring and audit programme.

Environmental Legislation, Standards and Guidelines

4.2 This fisheries impact assessment followed the criteria and guidelines set out in the EIAO-TM Annex 9 and Annex 17 in order to provide complete and objective identification and evaluation of potential fisheries impacts arising from the Project.

Assessment Methodology

4.3 The methodology for fisheries impact assessment followed the criteria and guidelines in Annexes 9 and 17 of the EIAO-TM. The study area for the purpose of fisheries impact assessment included areas within a distance of 500 m from the boundaries of the railway alignment and associated areas under the Project, such as terminus, stabling sidings, emergency rescue station, access roads, adits, ventilation buildings/emergency access points (EAP), works sites, barging points and above-ground conveyor system, if any, and the areas likely to be impacted by the Project. The findings of relevant studies and available information regarding the fisheries characters of the study area were reviewed. This was followed by ground truthing on the existing condition of fishpond operation within the study area, with key focus on pond culture resources and activities at Mai Po.

4.4 Excavation of the tunnels and associated structures will generate spoil from works areas. Six new barging points and one existing barging point have been proposed to transport the spoil generated from the Project to various disposal sites for reuse or disposing of (refer to Section 2 and Figure No. NOL/ERL/300/C/XRL/ENS/M51/063 for details). No marine works would be required in the proposed barging points apart from Lung Kwu Sheung Tan barging point (LKB). Marine fisheries impact assessment (refer to Appendix 4.2) has been undertaken to assess any potential impacts on nearby resources arising from the proposed minor marine dredging for the LKB. The assessment also covers Tsing Chau Tsai barging point (TCB) due to its close proximity to the Ma Wan Fish Culture Zone. Other proposed barging points with no marine works involved are distant from any important fisheries resources, adverse fisheries impact is not anticipated. These sites are therefore scoped out from the fisheries impact assessment.

4.5 Seawater cooling systems of the proposed West Kowloon Terminus (WKT) would be served by a pumping station which draws water from Victoria Harbour through intake unit and pump to the buildings through pipelines. Used water carrying waste heat from the heat exchanger of the seawater cooling system would be discharged through the outfall unit direct to Victoria Harbour. The construction of intake and outfall units would be conducted by replacing the existing concrete seawall (i.e. blockwork) with new precast seawall units. The potential marine fisheries impacts arising from the proposed seawater cooling system are further discussed in Appendix 4.2.

Description of the Environment and Baseline Conditions

4.6 The EIA Report of Proposed Comprehensive Development at Wo Shang Wai, Yuen Long (PPEL, 2008) recorded 22 fishponds (including active freshwater fishpond, inactive fishpond and fishpond in drying or maintenance stage) within the study area of the Mai Po VB (MPV). Polyculture of grass carp, tilapia, big head carp and grey mullet were commonly reared species in the freshwater fishponds. These active freshwater fishponds included fishpond under the Accredited Fish Farm Scheme to provide freshwater fish with quality assurance. Inactive fishponds were found abandoned from previous aquaculture activities and some are developing into marsh.

4.7 Pond fish culture industry is centred in the northwest New Territories. According to the latest information from the Agriculture, Fisheries and Conservation Department (AFCD, 2009), the local inland ponds, covering an area of approximately 1,160 ha, produced 2,266 tonnes of freshwater fish amounting to HK$41 million in 2008. Since the late 1970s, fishpond areas in the Deep Bay area have gradually declined and replaced by urban development. Table 4.1 presents the Agriculture, Fisheries and Conservation Department (AFCD)’s figures on fishpond area and annual fish production in Hong Kong from 1998 to 2008.

Table 4.1 Fishpond Area and Annual Fish Production in Hong Kong from 1998 to 2008

Year	Fishpond Area (ha)	Freshwater Fish Production (tonnes)
1998	1,110	4,900
1999	1,100	4,500
2000	1,060	2,820
2001	1,059	2,550
2002	1,030	1,989
2003	1,030	2,110
2004	1,030	1,980
2005	1,030	1,900
2006	1,030	1,940
2007	1,160	1,930
2008	1,160	2,266

Source: Data for year 1998 to 2000 was extracted from HyD (2004); data for year 2001 to 2008 was extracted from AFCD (2002, 2003, 2005, 2006, 2007, 2008a and 2009).

4.8 In 2008, about 92% of the fish farms were engaged in polyculture of big head carp, grass carp, common carp and silver carp in combination with tilapia or grey mullet, whilst the remaining 8% practiced monoculture of carnivorous species such as giant groupers, seabreams and spotted scat in brackish fishponds near to the coastline (AFCD, 2009). The majority of the fry and fingerlings were imported from the Mainland and Taiwan. Some of the grey mullet fry might also be caught in local coastal waters. Traditionally, fry were stocked in early spring and most fish species reach marketable size in 8 to 12 months.

4.9 In 2005, a voluntary Accredited Fish Farm Scheme was introduced by AFCD to enhance the competitiveness of the local aquaculture industry. Participating fish farms under the scheme are required to adopt a set of best aquaculture practices with a view to raising the environmental hygiene standards of the fish farms and the quality of cultured fish. Accordingly to the most updated information provided by AFCD in March 2009, a total of 151 ponds from 22 pond fish farms had joined the Scheme. The number of such accredited farms in Mai Po area is 6 comprising of 87 ponds and that for San Tin area is 5 with 23 operating ponds.

4.10 Ground truthing was conducted in July and October 2008 to review the existing condition of fishponds within the study area. Habitat maps showing location and condition of fishponds within the study area are provided in Figure Nos. NOL/ERL/300/C/XRL/ENS/M51/200 to 210.

4.11 There were approximately 80 fishponds (including both active and inactive fishponds) within the study area comprising about 30 ha area in total. Large-scale active fishponds were located within the study area of the MPV, which accounts for about 22 fishponds of 28.6 ha area (over 95% of total fishpond area in the study area). There were also about 35 (about 1.1 ha area) active fishponds within the study area of the Ngau Tam Mei VB (NTV) including small-scale ponds and ponds rearing aquarium fish. An active fishpond (about 0.2 ha) was also found within the study area of the temporary explosive magazine in Tai Shu Ha Road West (TSW) near Tai Tong. No active fishpond was found within the study area of the Tai Kong Po Emergency Access Point (TPP), the Shek Kong Stabling Sidings (SSS), the Pat Heung VB (PHV) and the Tse Uk Tsuen Works Area (TUW).

4.12 Twenty-two fishponds (about 6 ha in area) were found to be abandoned with vegetation growing within / along the edges of ponds. Appendix 4.1 provides representative photographs of active and inactive fishponds found within the study area.

4.13 All the active fishponds found in the study area were freshwater fishponds. In general, polyculture of grass carp, tilapia, big head carp and grey mullet were commonly reared in these fishponds. Small fishponds within the study area of the NTV were also used to rear aquarium fish such as goldfish and Koi (domesticated varieties of common carp Cyprinus carpio).

Table 4.2 Condition and Area of Fishponds recorded within the Study Area

Condition	Size (ha)	Activities
Active Fishpond	30	- Polyculture of grass carp, black carp, tilapia, big head carp and grey mullet - Rearing of aquarium fish such as goldfish and Koi - Accredited Fish Farm Scheme providing freshwater fish with quality assurance
Inactive Fishpond	6	- Abandoned from previous fishery activities - Vegetation growing such as Ipomoea cairica, Mikania micrantha and Phragmites spp.

Identification and Evaluation of Fisheries Impacts

Construction Phase

Habitat Loss

4.14 There would be no habitat loss or direct impact to active and inactive fishponds and their pond bunds within the study area. It is anticipated that no fisheries activities would be impacted. The locations of active and inactive ponds in relation to the proposed works areas are discussed in Table 4.3 and 4.4 below.

Permanent Resumption and Temporary Occupation of Fishponds

4.15 Permanent resumption or temporary occupation of fishponds and their pond bunds is not required, as no active and inactive fishponds would be occupied during the construction and operation phases.

Deterioration of Water Quality

4.16 The proposed construction works in Mai Po would have potential indirect off-site impacts on adjacent active fishpond, pond bund and drainage ditches due to construction dust deposition, site runoff and chemical waste spillage (e.g. oil and other pollutants from mechanical equipment). However, it is anticipated the impacts would be temporary and negligible with good site practices in place during the construction phase. The fishponds in the other study areas have a considerable distance from the proposed works area and it is not apparent that they have any physical linkage. Impacts to fisheries activities in these areas are considered very limited.

Hydrological Disruption

4.17 The whole Project alignment would be constructed underground in form of tunnel and there would be no direct impact on existing active and inactive fishponds. The tunnels adopt a twin cell tunnel configuration with interconnecting cross passages. The cross sectional size and alignment along the tunnel length would vary depending upon the geological conditions and method of construction. Tunnelling works for alignment section to the north of Kai Kung Leng would be constructed by bored tunnelling method using Tunnel Boring Machine (TBM) (refer to illustration on Figure No. NOL/ERL/300/C/XRL/ENS/M50/001). About 1.5 km of which would be running beneath Mai Po area where a large area of contiguous fish ponds is located.

4.18 To enable the launching of the TBM in the area, a small developed area in Mai Po would be occupied as a works area, namely Mai Po Ventilation / Construction Shaft (MPV). Cut and cover technique will be adopted to construct a shaft for TBM launching. Apart from the use of a TBM launching shaft towards Ngau Tam Mei and possibly towards Mainland during construction stage, the MPV will also be used as a ventilation point and emergency access point during operation phase.

4.19 Both TBM tunneling works and shaft construction works would not encroach on any fishponds in Mai Po area, but any potential hydrological impact to the operating fish farms due to groundwater drawdown is of concern. The following sections discuss the potential impact to groundwater and fishpond resulting from the proposed construction activities in Mai Po area.

Potential Hydrogeological Impact on Fishpond due to Cut and Cover Construction

4.20 During excavation of the launching shaft in Mai Po, water inflow could be a concern. The nowadays construction technique[1] would allow casting a continuous concrete wall underground, which could largely stop water from entering into the excavation area, before commencement of excavation works. However, before completion of the structure inside the excavation and backfilling the shafts, there would still be minor water inflow into the excavation area from the bottom formation. The inflow will be controlled by placing the continuous underground concrete wall deeper until acceptable water level would be achieved. Computer modelling is used for the estimation of groundwater drawdown outside the proposed shaft. During deep excavation works for construction of diaphragm wall (i.e. -30mPD), maximum groundwater drawdown of approximately 0.1 to 0.5 m is predicted at the nearest fish pond. It is anticipated that the groundwater drawdown would be lessened during shallow excavation. Such works would last for approximately six months, in the worst case scenario, the groundwater drawdown might have impact on the nearby fishpond water levels which in turn would affect the operation of fish ponds or lead to suspension of fish culture activities. The livelihoods of fish pond operators might also be affected. Therefore, proper implementation of precautionary and mitigation measures to groundwater drawdown (Appendix 11.8B Hydrogeological Impact Assessment) as well as emergency response plans are essential to minimise any potential impacts on fish farmers or fish culture activities. Although the chances of water drawdown in the fishpond (and / or its interconnected fishponds) located directly adjacent to the MPV cannot be ruled out, such localised and temporary drawdown is not expected to have extensive impact to other active fishponds or fish culture in Mai Po area located away from the MPV site. Since this method of construction has been used in many places all over the world including Hong Kong, it is a fail safe method for providing a safety construction underground with assurance against water flow and lateral ground pressure.

Tunnel Constructed by Bored Tunnelling Method under Mai Po Fishpond

4.21 Along the Project alignment, the underground tunnels pass through a very limited number of fish ponds except north of the MPV. The tunnels will pass under about 10 fish ponds north of MPV before crossing into Mainland. The tunnel would be about 20m deep under the fish ponds giving sufficient protection to the fish ponds.

4.22 Modern mechanised tunnel boring machines will be used to construct the tunnel under the fish ponds. These machines will use pressurised cutting face to balance the water pressure outside the excavation face as well the ground pressure. The gaps between the steel shell of the machine and boring head are sealed to prevent water inflow into the excavation. Water tight concrete tunnel lining in pre-cast segments will also be installed at a short distance of the cutting face.

4.23 During installation, the gaps between tunnel segments are joined with a water tight seal or gasket to prevent inflow of water into the completed tunnel. Therefore, the tunnel is water tight during construction and operation under the fish ponds. The current fishponds are therefore unlikely to be adversely influenced by bored tunnelling activities.

4.24 TBM tunnelling methods were deployed in some similar large scale projects in Hong Kong such as West Rail and Lok Ma Chau Spur Line. Comprehensive hydrological survey was carried out at Long Valley throughout the tunnel construction period of the Lok Ma Chau Spur Line project. A year-round groundwater baseline was established prior to the commencement of the TBM tunnelling to record groundwater level behaviour in respective wet and dry seasons. Groundwater level was closely monitored before, during and after each TBM drive. No significant deviations of groundwater level from the baseline resulted from the tunnelling works were identified.

4.25 The proposed construction activities in Mai Po area and the assessment on the risk of groundwater drawdown, precautionary measures and possible mitigation measures are summarized in Table 4.3 below.

Table 4.3 Key Works Elements and the Construction Methods to be Applied in the Mai Po Area

Construction Method	Works Elements	Risk of Groundwater Drawdown	Precautionary Measures	Possible Mitigation Measures
Cut and cover construction method	Mai Po construction Shaft (MPV)	· The construction shaft will be formed within retaining wall structures. It is anticipated that construction will be a diaphragm wall cofferdam with internal strutting (props and wailings) to provide the required lateral bracing. · The excavations for the shafts will only require temporary dewatering during their construction. Groundwater drawdown would be limited to 2m in order to avoid adverse settlement impacts. · It is anticipated that the groundwater level will be recovered upon the completion of works. · Potential impact on fishponds due to groundwater drawdown is low with the provision of effective precautionary measures such as toe grouting and recharge well system.	· Groundwater monitoring to collect baseline groundwater level and construction phase groundwater level. · The following precautionary measures shall put in place to minimize any groundwater drawdown outside the site boundary during temporary dewatering works: - Toe grouting shall be applied beneath the toe level of the temporary / permanent cofferdam walls as necessary to lengthen the effective flow path of groundwater from outside and thus control the amount of water inflow to the excavation. - Recharge wells should be installed as necessary outside the excavation to pump water obtained from the excavation back into the ground.	· No specific mitigation measure would be required providing appropriate construction control / practice is in place / carried out during the tunnel construction phase. · Monitoring of water level of fish pond. · Implementation of emergency response plan to avoid/minimize the potential impact during construction phase.
Bored tunnelling construction method (Undrained Lining)	· Huang Gang Park to Mai Po Tunnels · Mai Po to Ngau Tam Mei Tunnels	· The use of slurry / EPB TBM construction method and the selection of an impermeable “undrained” tunnel lining (installed prior to the advance of the TBM) should preclude groundwater inflow into the tunnels. · No potential water drawdown is anticipated. · Potential impact on fishponds due to groundwater drawdown is low.	· Groundwater monitoring to collect baseline groundwater level and groundwater level during construction phase.	· No specific mitigation measure would be required providing appropriate construction control / practice is in place / carried out during the tunnel construction phase. · Monitoring of water level of fish pond. · Implementation of emergency response plan to avoid/minimize the potential impact during construction phase.

Construction Noise and Vibration

4.26 Active fishponds in the study area of the NTV and the TSW were located far away (at least approximately 350 m from works area of the NTV and 175 m from the temporary access road of the TSW). Inactive fishponds within study area were also distant from the works areas (from approximately 200 m to 425 m). Noise and vibration impact to these fishponds is considered negligible and therefore will not be discussed further. Potential impacts to fishponds in Mai Po are discussed below.

Potential Vibration and Construction Noise Impact to Fishponds adjacent to MPV

4.27 The MPV ventilation / construction shaft in Mai Po would be constructed over an open storage area which is situated approximately 120 m from the nearest active fishpond (where the fishpond is approximately 15 m away from the MPV works site hoarding). The construction activities related to the MPV site would involve installation of diaphragm wall, bulk excavation, concrete works, TBM erection and driving, access road and ventilation building construction as well as filling out of tunnel. Percussive piling of relatively high vibration impact would be avoided during diaphragm wall formation, it is not likely the fishponds nearby would be affected by the proposed MPV shaft construction.

4.28 The predicted maximum mitigated construction noise levels will be 73 dB(A) with the adoption of mitigation measures such as quieter plants, enclosure / shed / hoarding, noise insulating fabric, movable barrier, silencer, etc., while the background noise levels in MPV ranged from 68 – 70 dB(A) (Refer to Section 5). Given that the mitigated construction noise level are of comparable magnitude to the background noise level, it is therefore anticipated that there would be no significant noise impact to fishponds near the MPV.

4.29 Site hoarding of approximately 2.4 m in height will be set up around the works boundary to shield the nearby fishponds from the disturbance due to construction noise and human activities, it is anticipated that noise impact on fish culture in the Mai Po area would be minimal. The impacts from construction noise would be temporary and negligible with noise mitigation measures and good site practices in place during the construction phase.

Potential Vibration Impact to Fishponds above Bored Tunnels in Mai Po Area

4.30 The underground works would be located at least 26 m below the local ground level in the area between boundary and Mai Po. Potential ground-borne noise impacts in Mai Po during the construction phase would arise mainly from tunnel boring machine (TBM) operation for tunnelling. No percussive piling would be conducted in Mai Po area (i.e. MPV). Currently there are no criteria to access the acceptability of ground-borne noise and vibration level to wildlife or animals in captivity, however, reference are made to the study in Section 6 Ground-borne Noise Impact Assessment. According to the predicted ground-borne noise levels, as shown in Table 6.10 and Table 6.15 in Section 6, no identified Noise Sensitive Receivers (NSRs) in Mai Po area would be subject to ground-borne noise levels exceeding the daytime noise limit of 65dB(A), due to TBM operation. Based on the daily progress of the TBM at Lok Ma Chau Spur Line of 8-11m per day, any potential impact generated from TBM operation is expected to be temporary in nature.

Blocking of Access to the Surrounding Fishponds

4.31 There would be no blockage of access to the fishponds within the study area during the construction phase, and therefore disturbance to fisheries activities is not anticipated.

Operational Phase

Hydrological Disruption

4.32 As discussed in above sections, the use of a closed face TBMs in conjunction with an “undrained” tunnel lining effectively precludes the ingress of water into the tunnel during and following construction. There would be no adverse impact due to hydrological disruption during the operation of the railway.

Blocking of Access to the Surrounding Fishponds

4.33 There would be no blocking of access to the fishponds within the study area during the operation of the railway, and therefore disturbance to fisheries activities is not anticipated.

Restriction on Pond Culture Related Activities

4.34 The tunnel alignment between the boundary and Ngau Tam Mei section would be operated approximately 25 to 60 m below local ground level. No existing fishponds are located within the railway protection zone[2] of the Project alignment and it is not anticipated to impose any restriction on normal pond culture activities such as excavation (e.g. pond formation and ploughing) due to the operation of the tunnel underneath.

Potential Vibration Impact to Fishponds above Tunnels in Mai Po Area

4.35 When trains operate in tunnels that are located in close proximity to aboveground structures, there is a possibility that vibrations associated with train passbys will be transmitted through the ground. Ground-borne noise levels have been predicted using a conservative approach based on the maximum operation capacity of railway system. All of the predicted ground-borne noise levels at existing residential receivers are well below the EIAO ground-borne noise criteria, generally as a result of deep underground alignment. It is therefore envisaged that the construction and operation of the Project would not have adverse effect to the fish culture.

Overall Summary of Fisheries Impact

4.36 The evaluation of fisheries impact on the Project followed the criteria set out in Annex 9 of the EIAO-TM and is shown in Tables 4.4 to 4.5.

Table 4.4 Evaluation of Fisheries Impact to Active and Inactive Fishponds within Study Area of the MPV

Criteria	Active Fishponds within Study Area of the MPV	Inactive Fishponds within Study Area of the MPV
Nature of impact	No direct loss, resumption nor occupation of active fishponds and their pond bunds during construction and operation phases. Construction Phase Potential short term and reversible indirect impact from noise, construction dust deposition, site runoff and chemical / oil spillage during construction period. But such impacts are localised and are not anticipated to have adverse impact on fisheries activities with noise mitigation measures and good site practices in place.	No direct / indirect impacts on inactive fishponds and their pond bunds during construction and operation phases.
Size of affected area	No fishpond or their pond bund would be directly affected by the proposed works. Construction Phase Affected area would be localised and restricted to pond adjacent to the works area. An active fishpond (approximately 1.9 ha) in MPV that might be indirectly affected is separated from the works area by a drainage ditch. (Figure No. NOL/ERL/300/C/XRL /ENS/M51/200 refers). Operation Phase Nil	No inactive fishpond affected as they are distant from the works area (from approximately 200 m to 425 m from works area. (Figure No. NOL/ERL/300/C/XRL/ENS /M51/200 refers)
Loss of fisheries resources / production	Since no fishpond would be directly affected, impact on culture fisheries resources due to construction and operation activities of the Project is insignificant.	No loss of fisheries resources / aquaculture production due to construction and operation activities of the Project.
Destruction and disturbance of nursery and spawning grounds	No nursery and spawning grounds of commercially important species are disturbed or destroyed during construction and operation phases.	No nursery and spawning grounds of commercially important species are disturbed or destroyed during construction and operation phases.
Impact on fishing activity	No fishing activity would be affected during construction and operation phases.	No fishing activity would be affected during construction and operation phases.
Impact on aquaculture activity	No impact on existing aquaculture activities as there would be no direct impact on fishponds. Indirect disturbance impact from construction activities is not expected to affect the aquaculture activity in the adjacent fishpond with good site practices in place.	No aquaculturist or aquaculture farm affected.
Impact on pond fish culture due to groundwater drawdown and vibration	Construction Phase The use of a closed face TBMs in conduction with an “undrained” tunnel lining effectively precludes the ingress of water into the tunnel during construction. There would be no adverse impact due to hydrological disruption during the construction of the railway. The continuous wall underground would largely stop water from entering into the excavation area for the MPV construction shaft, any minor inflow to the excavation from the bottom formation can be largely controlled through toe grouting and / or recharge well. Potential impact to fishponds adjacent to MPV site would be localised and temporary in nature. Potential impact on fishponds due to groundwater drawdown is low with the provision of precautionary measures. There are no criteria for the assessment of vibration impact to wildlife / pond fish, however, all of the predicted ground-borne noise levels at existing residential receivers are well below the EIAO ground-borne noise criteria. The construction of deep underground Project alignment would not have adverse impact to the fish culture. The construction noise impact generated during MPV ventilation shaft construction would low with implementation of effective noise mitigation measures such as site hoardings and movable barriers. Vibration impact to fishponds has been largely minimised through avoidance of percussion piling. Operation Phase The use of a closed face TBMs in conduction with an “undrained” tunnel lining effectively precludes the ingress of water into the tunnel after construction. There would be no adverse impact due to hydrological disruption during the operation of the railway. After the completion of bore tunnelling works, permanent structures (Mai Po Ventilation Building) will be constructed and backfilling will be carried out. Groundwater seepage into the permanent structures is not expected and hence there will be no impact to water level of fishponds in the area due to MPV operation. There are no criteria for the assessment of vibration impact to wildlife / pond fish, however, all of the predicted ground-borne noise levels at existing residential receivers are well below the EIAO ground-borne noise criteria. The operation of deep underground Project alignment would not have adverse impact to the fish culture. The operation of Mai Po Ventilation Building is not expected to cause significant noise / vibration impact to nearby fishponds.	Construction Phase The use of a closed face TBMs in conduction with an “undrained” tunnel lining effectively precludes the ingress of water into the tunnel during construction. There would be no adverse impact due to hydrological disruption during the tunnel construction. There are no criteria for the assessment of vibration impact to wildlife / pond fish, however, all of the predicted ground-borne noise levels at existing residential receivers are well below the EIAO ground-borne noise criteria. The construction of deep underground Project alignment would not have adverse impact to the fish culture. Operation Phase The use of a closed face TBMs in conduction with an “undrained” tunnel lining effectively precludes the ingress of water into the tunnel after construction. There would be no adverse impact due to hydrological disruption during the operation of the railway. There are no criteria for the assessment of vibration impact to wildlife / pond fish, however, all of the predicted ground-borne noise levels at existing residential receivers are well below the EIAO ground-borne noise criteria.

Table 4.5 Evaluation of Fisheries Impact to Other Active and Inactive Fishponds within the Study Area of other Works Sites

Criteria	Other Active Fishponds within the Study Area	Other Inactive Fishponds within the Study Area
Nature of impact	No direct / indirect impacts on active fishponds and their pond bunds during construction and operation phases.	No direct / indirect impacts on inactive fishponds and their pond bunds during construction and operation phases.
Size of affected area	No active fishpond affected during construction and operation phases as they are located far away from the works area (at least approximately 350 m from works area of the NTV (Figure No. NOL/ERL/300/C/XRL/ ENS/M51/202 refers) and 175 m from the temporary access road of the TSW near Tai Tong (Figure No. NOL/ERL/300/C/XRL/ENS /M51/210 refers).	No inactive fishpond affected during construction and operation phases as they are located far away from the works area (at least approximately 250 m from works area of the NTV (Figure No. NOL/ERL/300/C/XRL/ ENS/M51/202 refers), 100 m from emergency vehicular access of the TPP, 90 m from works area of the SSS (Figure Nos. NOL/ERL/300/ C/XRL/ENS/M51/203 to 209 refer) and 165 m from the temporary access road of the TSW near Tai Tong (Figure No. NOL/ERL/300 /C/XRL/ENS/M51/210 refers).
Loss of fisheries resources / production	No loss of fisheries resources / aquaculture production during construction and operation phases.	No loss of fisheries resources / aquaculture production during construction and operation phases.
Destruction and disturbance of nursery and spawning grounds	No nursery and spawning grounds of commercially important species are disturbed or destroyed during construction and operation phases.	No nursery and spawning grounds of commercially important species are disturbed or destroyed during construction and operation phases.
Impact on fishing activity	No fishing activity would be affected during construction and operation phases.	No fishing activity would be affected during construction and operation phases.
Impact on aquaculture activity	No aquaculturist or aquaculture farm affected during construction and operation phases.	No aquaculturist or aquaculture farm affected during construction and operation phases.

Mitigation Measures of Adverse Fisheries Impacts

4.37 According to EIAO-TM Annex 17 guidelines, mitigation measures are discussed in this section to avoid, minimise and compensate for identified ecological impacts.

Avoidance

4.38 Impacts on significant fisheries resources are largely avoided through the alignment selection process and construction methods for the Project, as discussed in Section 2. Direct loss of active fishponds, inactive fishponds and pond bunds, blockage of access to surrounding fishponds, and restriction on pond culture related activities have been avoided. The potential impact on hydrology would also be largely avoided through the implementation of precautionary measure during tunnelling works. Details of this mitigation and contingency plans to monitor groundwater levels are presented in the Hydrogeological Impact Assessment (Appendix 11.8B).

Mitigation

4.39 The construction and operational impacts of the Project are expected to be low and acceptable. The following mitigation measures are recommended to further reduce impacts to fisheries resources. The mitigation measures discussed below should be implemented throughout the construction phase.

Construction Phase

Deterioration of Water Quality

4.40 Good site practices and proper dust and water quality control measures should be implemented to minimize the indirect off-site impacts on the adjacent fishponds at the MPV. These include site confinement with fencing / hoarding erection at the perimeter of the works area, stockpile covering by impervious sheeting to avoid spread of construction dust, and proper handling, storage and disposal of chemical waste to avoid contamination of the existing water system, etc. As such, no specific mitigation measure would be required.

Hydrological Disruption

Tunnel Constructed by Bored Tunnelling Method under Mai Po Fishponds

4.41 As discussed in Section 4.21 to 4.24, the use of a closed face TBMs in conduction with an “undrained” tunnel lining effectively precludes the ingress of water into the tunnel during and post construction. As such TBM tunnelling method would have, in effect, no impact on the hydrogeological conditions of the fishponds above. With appropriate construction practices is in place, no specific mitigation measure is required during tunnelling construction. However, groundwater monitoring should be conducted during the tunnelling works as a precautionary measure (Table 4.6 refers).

Cut and Cover Construction in MPV Shaft

4.42 In order to reduce the potential groundwater drawdown, the Contractor should adopt suitable water control strategies while undertaking the shaft construction near Mai Po fishponds. In the event that the groundwater table is observed to be lowered unacceptably even after the application of these water control strategies then post grouting or other similar acceptable remedial measures should be undertaken from within the MPV construction shaft as a suitable mitigation measure. These strategies are described in Paragraph 7.4.1 to 7.4.6 of Appendix 11B and summarised as below.

Table 4.6 Precautionary Measures to Potential Hydrological Impacts from Bore Tunnelling and Shaft Construction in Mai Po

Risk Management Strategy	Applicable Construction Method	Description
Comprehensive Groundwater Monitoring	· Bore Tunnelling Construction Method · Cut and Cover Construction Method	This programme should include installation of monitoring wells at regular intervals along the alignment in Mai Po and on target areas of specific interest such as the cut and cover or TBM tunnel interfaces, etc. Pre-construction monitoring should also be undertaken such that baseline groundwater levels can be established and any seasonal (or other) variations in groundwater level identified. Such pre-existing groundwater variations, once identified, can then be excluded when determining the impact of construction on the local groundwater regime. A detailed instrumentation and monitoring programme will be developed in detailed design stage to monitor both the proposed works and the impact of those works on the adjacent area.
Toe Grouting	· Cut and Cover Construction Method	Toe grouting should be applied beneath the toe level of the temporary/permanent cofferdam walls as necessary to lengthen the effective flow path of groundwater from outside and thus control the amount of water inflow to the excavation.
Groundwater Recharge Well	· Cut and Cover Construction Method	Recharge wells should be installed as necessary outside the excavation to pump, water obtained from the excavation back into the ground.

Noise and Vibration

4.43 Details of mitigation measures to control noise and vibration due to the construction of the Project are briefly summarised as below. Details are presented in Section 5 and Section 6.

4.44 The impacts from construction air-borne and ground-borne noise would be temporary and negligible with good site practices in place during the construction phase; such as:

l Only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction program;

l Silencers or mufflers on construction equipment should be utilized and should be properly maintained during the construction program;

l Machines and plant (such as trucks) that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum;

l Plant known to emit noise strongly in one direction should, wherever possible, be orientated so that the noise is directed away from the nearby fishponds;

l Material stockpiles and other structures should be effectively utilized, wherever practicable, in screening noise from on-site construction activities;

l Use of movable barrier for certain powered mechanical equipment (PME); and

l Use of noise enclosure or acoustic shed to cover stationary PME.

4.45 Consultation will be conducted with fish operators in Mai Po before tunnelling starts. The method of construction, potential impact and mitigation measures will be fully explained to the operators at the meeting. A monitoring and emergency response plan (to be prepared up by the contractor) in relation to impacts due to noise/vibration, will form part of the EM&A requirement in the EM&A Manual subject to approval by EPD and AFCD before commencement of the relevant works.

4.46 Monitoring at the time of TBM operation is recommended to confirm and monitor the ground-borne noise levels. An EM&A programme, together with careful scheduling of the works and close liaison with affected parties which would have exceedance of the noise criterion, is recommended to minimise the impact from the operation of TBM.

Operational Phase

Hydrological Disruption

4.47 No specific mitigation measure would be required as there would be no adverse impact due to hydrological disruption provided that appropriate construction control / practices are in place.

Blocking of Access to the Surrounding Fishponds

4.48 There would be no blockage of access to the fishponds within the study area during the operation of the railway. As such, no specific mitigation measure would be required.

Restriction on Pond Culture Related Activities

4.49 No specific mitigation measure would be required as restriction on pond culture related activities is not anticipated as the tunnel alignment is not anticipated to impose any restriction to normal pond culture activities.

Noise and Vibration

4.50 With the predicted operation ground-borne noise levels complying with the stipulated noise criteria at existing NSRs, mitigation measures are not required during operation phase.

Environmental Monitoring and Audit

Monitoring of Impact from Groundwater Drawdown

4.51 Groundwater levels will be monitored along the whole Project alignment in pre-construction and construction stages as part of the comprehensive groundwater monitoring strategy (details refer to Appendix 11.8B Hydrogeological Impact Assessment). A monitoring and emergency response plan (to be prepared by the Contractor), in relation to potential impacts due to groundwater drawdown, will form part of the EM&A requirement in the EM&A Manual subject to approval by EPD and AFCD before commencement of the tunnelling and MPV construction in Mai Po area. The plan should include, but not be limited to, details of monitoring locations and programme, a mechanism to monitor the implication from the works to the groundwater system and fish ponds including their water levels, action levels and emergency responses such as immediate action, remedial action and investigation.

Monitoring of Impact from Noise and Vibration

4.52 A monitoring and emergency response plan (to be prepared by the Contractor), in relation to potential impacts on fishponds in Mai Po Area due to noise/vibration, will form part of the EM&A requirement in the EM&A Manual subject to approval by EPD and AFCD before commencement of the tunnelling and MPV construction in Mai Po area.

Conclusion

4.53 Potential impacts on significant fisheries resources have been avoided through alignment selection process for the Project. There would be no direct impact on fisheries activities due to habitat loss, resumption / occupation of fishponds or restriction on pond culture related activities associated with the Project. Indirect impacts on fisheries resources due to groundwater drawdown, deterioration of water quality by construction dust, construction noise, site runoff and chemical / oil spillage would be negligible with good site practices and proper mitigation measures in place. Monitoring programme on impacts from groundwater drawdown, noise, and vibration would be conducted.

Reference

Agriculture, Fisheries and Conservation Department 2002. Departmental Annual Report 2001 – 2002. Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

Agriculture, Fisheries and Conservation Department 2003. Departmental Annual Report 2002 – 2003. Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

Agriculture, Fisheries and Conservation Department 2005. Departmental Annual Report 2003 – 2005. Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

Agriculture, Fisheries and Conservation Department 2006. Departmental Annual Report 2005 – 2006. Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

Agriculture, Fisheries and Conservation Department 2007. Departmental Annual Report 2006 – 2007. Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

Agriculture, Fisheries and Conservation Department 2008a. Departmental Annual Report 2007 – 2008. Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

Agriculture, Fisheries and Conservation Department 2008b. Series of Good Aquaculture Practice: Series 3 - Pond Culture Management. Agriculture, Fisheries and Conservation Department, Hong Kong Special Administrative Region Government.

Agriculture, Fisheries and Conservation Department 2009. Fisheries: Aquaculture.

http://www.afcd.gov.hk/english/fisheries/fish_aqu/fish_aqu.html

Highways Department 2004. Improvements to San Tin Interchange EIA Report. Highways Department, Hong Kong Special Administrative Region Government.

Lau, S.K., Lee, J., & Young, L. 2003. History and importance of pond-fish farming in and around the Mai Po Inner Deep Bay Ramsar Site, Hong Kong SAR, P.R. China. Turning the Tides: 287-298.

Profit Point Enterprises Limited (Ltd.) 2008. Proposed Comprehensive Development at Wo Shang Wai, Yuen Long, Environmental Impact Assessment Report. Profit Point Enterprises Limited (Ltd).

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[1] Construction sequence (especially for cut and cover construction of shaft) in relation to groundwater drawdown: It is proposed to construct diaphragm wall, sand drains, and struts as the temporary excavation and lateral support system. Monitoring points will be installed and readings of groundwater drawdown will be taken prior to the commencement of works and throughout the construction period. Subsequent to the completion of diaphragm wall and sand drain installation, a series of observation wells, pump wells and recharge wells will be installed prior to the commencement of excavation work. To minimise groundwater drawdown of less than 1m within surrounding fish pond areas, recharge well system will be provided as a precautionary measure to avoid undesirable drawdown. The groundwater from the dewatering within the cofferdam may be used for the recharge. The proposed recharge water shall be sampled and tested before use to ensure the water is of the required quality and to avoid any adverse impact on groundwater or ecology of the existing ponds. Appendix 4.3 presents the contours of predicted groundwater drawdown with provision of recharge well system. A full scale pumping test will also be undertaken for assessing the groundwater drawdown due to dewatering. The pumping test also serves the purpose of verifying the water cut off effectiveness and the effectiveness of sand drains. Excavation within the cofferdam will be undertaken upon satisfactory results of the pumping test. Staged dewatering and excavation with installation temporary struts will be undertaken within the cofferdam. It is then followed by TBM insertion and removal at the ends of the cofferdam. The permanent structures will be constructed and backfilling will be carried out. Subsequently, the dewatering pump will be switched off.

[2] Appendix A of Practice Note (Reference No. PNAP 77) for Authorized Persons and Registered Structural Engineers of Building Department : Mass Transit Railway Protection Railways Ordinance Mass Transit Railway (Land Resumption and Related Provisions) Ordinance Buildings Ordinance Scheduled Area No. 3:

Section B 1(d): No pile, foundation, borehole, well, soil nail, horizontal drain, rock bolt / dowel or other geotechnical installation shall be driven or constructed within a distance of 3 m from any point of the underground railway structures.

Section B 1(e): Any part of an anchor, if allowed, shall be more than 3 m away from any part of a MTR structure / installation, and the centroid of the fixed length of the anchor shall be more than twice the fixed length away from any MTR structure / installation.