This section provides a description of the proposed interim sewage treatment plant (STP) and effluent reuse facility, which includes details relating to the need for and environmental benefits of the Project, design and the layout of the Project, background information on the alternatives considered, as well as indicative construction methods and tentative programme details.
The Project lies within an area designated for “Other Specified Uses (Comprehensive Development to include Wetland Restoration Area)” under the approved Mai Po & Fairview Park Outline Zoning Plan (S/YL-MP/6). The proposed STP is located within the Comprehensive Development at Wo Shang Wai, Yuen Long (hereafter referred as WSW development). The STP, the effluent reuse system and associated works will be located on the basement level within the WSW development. The WSW development is bounded by Castle Peak Road – Mai Po and San Tin Highway to the east, with fish ponds to the north, Wo Shang Wai Village to the south-west, and residential developments (i.e., Royal Palms and Palms Spring) to the south. The location of the Project is shown in Figure 2.1b.
In the 1940s and 1950s, the surrounding of the Project site comprised of brackish rice paddies and were converted to fishponds in the 1960s. The ponds were progressively filled from around 1987 due to increased demand in open storage facilities in the North West New Territories. From the aerial photo taken on 18 August, 1990, it is evident that about 90% of the ponds in the site were filled. Around Year 2000, the Project site is filled and become grassland. The site became the WSW development construction site since Year 2010. Historical aerial photos of the site prior to becoming the WSW development is shown in Figure 2.2.
The STP is a 1-storey high building structure with effluent reuse facility located in the basement of the building, the footprint of the STP building is about 225 m2. The height of the building structure is anticipated to be approximately 11.40mPD with formation level to be approximately -4.9mPD. The basement level of the proposed interim STP is expected to connect with the basement level of the WSW Development. The effluent reuse facility will comprise of the following:
● Equalization tank;
● Reclaimed water storage tank;
● Anoxic tank;
● Aerobic / membrane tank;
● An ultraviolet (UV) steriliser;
● Sludge tank;
● Treated effluent collection tank;
● Emergency storage tank; and
● Associated pumping facilities and piping network.
The locations of the above components are shown in Figure 2.3, where the piping network is shown in Figure 5.2. The STP will be designed generally in accordance with EPD’s Guidelines for the Design of Small Sewage Treatment Plant.
All pipes and fittings used for reclaimed water supply and associated distribution system will be in a specific colour (to be determined during detailed design stage) for distinguishing from the ones used for fresh water supply.
Membrane Bioreactor (MBR) technology has been proposed for sewage treatment, with a capacity of 1,446m3/d. MBR is a combined system of biological treatment and microfiltration process, which is capable of generating high quality effluent. Effluent that has gone through the MBR process will undergo ultraviolet (UV) disinfection, which will serve as second disinfection barrier to ensure E.coli level in the effluent be reduced to non-detectable level. Subsequently, sodium hypochlorite solution will be added to the UV-disinfected effluent so as to maintain the total residual chlorine level of above 1mg/L in accordance with the Water Supplies Department’s (WSD) recommended water quality standard, prior to reuse the effluent on-site for toilet flushing and landscape irrigation [1] Samples of reclaimed water will be taken regularly and tested to ensure compliance with reuse criteria. Furthermore, regular checking/inspections of the reclaimed water supply and associated distribution systems with the use of non-toxic dye will be carried out, to identify any possible cross connection to the fresh water supply and distribution system.
All reclaimed water will be fully reused for toilet flushing and irrigation of landscape areas. To enable the reclaimed water to be safely reused, the onsite STP will be designed to meet stringent treatment standards. The treatment standards adopted are based on the reuse water quality standards recommended in the “Water Supplies Department Inter-departmental Working Group on the Implementation of Reclaimed Water Supply in Sheung Shui and Fanling” for non-portable uses. Details of the criteria are summarised in Table 2.1 below and presented in Section 5.5.2.3.
Table 2.1: WSD Reuse Water Quality Standard for Non-Potable Uses
|
Water Quality Parameter |
Unit |
WSD Criteria (Irrigation & Non-Potable Uses) |
|
pH |
- |
6-9 |
|
Turbidity |
NTU |
≤ 5 |
|
Total Suspended Solids |
mg/l |
≤ 5 |
|
BOD5 |
mg/l |
≤ 10 |
|
E. coli |
cfu/100ml |
Non-detectable |
|
Total Residual Chlorine |
mg/l |
≥ 1 (out of treatment system) ≥ 0.2 (at point of use) |
|
Dissolved Oxygen (DO) |
mg/l |
≥ 2 |
|
Colour |
Hazen Unit |
≤ 20 |
|
Threshold Odour Number (TON) |
TON |
≤ 100 |
|
Ammonia nitrogen |
mg/l |
≤ 1 |
|
Synthetic detergents |
mg/l |
≤ 5 |
Note: The water quality standards for all parameters shall be applied at the point of use, unless otherwise specified.
A reclaimed water storage tank with a minimum capacity of 1,180m3 (3 times of the net daily production rate of reclaimed water) will also be constructed, in case of adverse weather condition (i.e., successive heavy rainy days) to store any excessive treated effluent, which will be progressively consumed in following period. Any further excessive reclaimed water will be tanked away to public sewage treatment works. According to the approved Sewerage Impact Assessment (SIA) for the Project (see Appendix 2.1), the buffer tank will be sized with adequate volume, including 1-day effluent storage capacity reserved as contingency, to cater for most of the extreme weather condition. Level sensors connected with alarm signalizing system will also be installed, to monitor the storage volume to avoid overflow of treated effluent. A warning signal will be generated automatically to alert the manager when the flow in the tank reached a pre-set level, allowing sufficient time for arranging tanker service to tank away excessive treated effluent.
Sludge produced in the process will be screened and dewatered, the dewatered sludge will be collected by a licensed collector at regular intervals for disposal of at landfill. The transfer of dewatered sludge to tankers will be carried out in the basement where forced ventilation will be provided.
The flow diagram of the operation of the facilities is shown in Figure 2.4.
A team of competent technicians will be assigned to operate the interim STP. Training workshops will be provided to all management and operation staff on the proper use of reclaimed water. An Operation and Maintenance (O&M) Manual will be drawn up detailing operating procedures and precaution measures, of which the technicians should be fully conversant with. In addition, the following will also be implemented:
● Maintaining the STP in a tidy state through regular hosing down, scraping of walkways, whitewashing walls, cleaning and painting metalwork and maintaining adequate lighting and ventilation;
● Hire qualified personnel to inspect and maintain the plant on a regular basis;
● Adequate spare parts will be stored and made readily available; and
● Requirements of Fire Services Department for bulk storage of sodium hypochlorite solution will be properly observed under the Dangerous Goods Ordinance (Cap. 295).
The use of reclaimed water during operation phase may potentially cause health impacts. However, as described above, reclaimed water will only be used for toilet flushing and landscape irrigation. Therefore, the greatest chance for potential health impacts to occur will be due to incorrect connection of the potable water and reclaimed water pipes at the toilets.
Pipes for reclaimed water will be easily differentiable from potable water pipes (i.e., watering signs, colour-coded, different pipe sizes) to avoid incorrect connections and contamination of potable water pipes. A range of other engineering and management measures will be adopted to prevent of cross contamination and misuse of reclaimed water, as described below.
Engineering Measures
● Water to be supplied for potable use, toilet flushing and irrigation should be stored in three different tanks in different colours and clearly labelled;
● All pipes and fittings used for reclaimed water supply and associated distribution system should be purple in colour (exact colour to be confirmed during detailed design stage) for distinguishing them from the pipes and fittings used for fresh water supply and its distribution system;
● Regular checking/inspections of the reclaimed water supply and associated distribution systems should be carried out to identify any possible cross connection to the fresh water supply and distribution system. Non-toxic dye may be used in the checking/inspections;
● Samples of treated effluent will be taken regularly through an easily accessible sampling point and tested to ensure compliance with reuse criteria;
● Non-return valves will be installed on both the inlet pipes feed from reclaimed water storage tank and fresh water supply mains, to the toilet flushing and irrigation water storage tanks; and
● All precaution measures will be clearly stated in the O&M Manual of the STP, toilet flushing and irrigation systems.
Management Measures
● Warning plate with sign and letter “NOT FOR POTABLE USE” would be shown on the toilet flushing and landscape irrigation storage tanks, and tagged on all accessible water taps supplying reclaimed water if any within the WSW developments;
● All water taps of reclaimed water at communal areas if any should be locked to avoid misuse of reclaimed water;
● Proper signage, promotion and training workshops will be provided periodically to all management and operation staff of the WSW Development, as well as future land owners on the proper use of reclaimed water and potable water;
● All precaution measures will be clearly stated in the management manual of the WSW Development; and
● Operators of landscape irrigation will be required to wear protective gears to minimise direct contact with reclaimed water whilst carrying out irrigation works.
With the implementation of the aforementioned measures, potential health impacts are not anticipated.
Other Projects with Reuse of Reclaimed Water for Non-Potable Use
Table 2.2 below is a list of projects that have adopted the reuse of reclaimed water in Hong Kong.
Table 2.2: Summary of Hong Kong Project Utilizing Reclaimed Water for Non-Potable Use
|
Project |
Non-Potable Use |
Reference |
|
Reuse of Treated Sewage Effluent from Redeveloped Lo Wu Correctional Institution |
● Toilet flushing |
DIR – 174/2008 |
|
Liantang / Heung Yuen Wai Boundary Control Point and Associated Works |
● Irrigation |
AEIAR – 161/2011 |
|
Water Reclamation Facilities for Stonecutters Island, Sham Tseng and Siu Ho Wan Sewage Treatment Works |
● Toilet flushing ● Make-up water ● Ground and facility washing |
DIR – 183/2009 |
|
Reuse of Treated Effluent from Ngong Ping Sewage Treatment Plant for Toilet Flushing |
● Toilet flushing |
DIR – 080/2003 |
|
Outlying Islands Sewerage Stage 2 – Upgrading of Tai O Sewage Collection, Treatment and Disposal Facilities |
● Toilet flushing ● Process cleansing |
AEIAR – 209/2017 |
|
North East New Territories New Development Areas |
● Toilet flushing ● Irrigation ● District cooling system |
AEIAR – 175/2013 |
|
Water Reclamation Facilities in Shatin Sewage Treatment Works |
● Polymer preparation ● Irrigation |
DIR – 177/2009 |
|
Phase III Redevelopment of the Hong Kong Federation of Youth Groups Jockey Club Sai Kung Outdoor Training Camp |
● Irrigation ● Flushing |
AEIAR – 157/2010 |
|
Demonstration Scheme on Reclaimed Water Uses in the North District |
● Household toilet flushing ● Unrestricted irrigation and water features (e.g., decorative streams and fountains) |
DIR – 125/2005 |
|
Water Reclamation Facilities in Pumping Station and Preliminary Treatment works of Drainage Services Department |
● Ground and facility washing ● Toilet flushing ● Landscape irrigation |
DIR – 181 /2009 |
|
Water Reclamation Facilities for Yuen Long, Sai Kung and Stanley Sewage Treatment Works |
● Make-up water for deodorizer ● Ground and facility washing ● Toilet flushing ● Landscape irrigation |
DIR 182/2009 |
|
Tseung Kwan O Area 86 Property Development – Rainwater and Greywater Recycling |
● Landscape irrigation ● Street cleaning ● Water features |
DIR – 137/2006 |
|
Water Reclamation Facility at Tai Po Sewage Treatment Works |
● Ground and facility washing ● Toilet flushing |
DIR 214 / 2011 |
|
Reuse of Treated Wastewater for Cooling Tower make up in Planned Food Factory at No. 3 Dai Shun Street Tai Po Industrial Estate |
● Cooling tower make-up water |
DIR – 232/2013 |
As stated in Section 1.1, it is understood that a number of sewage projects have been proposed to upgrade the existing system in North West New Territories. As such, it was anticipated that domestic effluent from the WSW development can be discharged via the public sewer during the preparation of the EIA study for the WSW Development. However, according to latest available information, the implementation programme of the government sewerage system is currently uncertain.
Therefore, a temporary measure to handle the sewage generated from the WSW Development before the availability of public sewerage connection is necessary.
In accordance with the prevailing water quality control policy, there should be no net increase in pollution load to Deep Bay. The use of existing discharge from Wo Shang Wai Village for co-treatment in order to offset the additional pollutant load had been considered but was found insufficient to meet the “no net increase” requirement. As such, it is proposed to reuse all reclaimed water for flushing and landscape irrigation within the WSW Development, in order to meet the “no net increase” requirement.
The major environmental benefit of the Project will be the reduction of wastewater discharge to receiving waterbodies thereby reducing pollution load to the environment. Particularly, the WSW Development is located where direction of water flow would eventually discharge to the Shenzhen River in the Deep Bay Water Control Zone. The Deep Bay is an important habitat recognised as wetland of international importance. Reducing wastewater discharge to the Deep Bay area will protect the important habitat and wildlife of the Deep Bay region, which is also the underlying principle of the “no net increase in pollution load to Deep Bay” under the prevailing water quality control policy.
Currently, 70-80% of Hong Kong’s freshwater needs are met by importation from Mainland China (i.e., Dongjiang, Guangdong). The reuse of reclaimed water for landscape irrigation and toilet flushing will reduce the overall freshwater demand during operation of the WSW Development.
Furthermore, it is the Hong Kong Government’s long term objective to increase water sources (including grey water reuse) and promote water conservation, with the aim to become more water sufficient locally and strengthen local water security. The Project, although relatively small scale, is in line with the Total Water Management initiatives and contributing positively to the Government’s long term aim towards sustainable development.
In the absence of the proposed STP, discharge of sewage generated from the WSW Development will be impossible. As mentioned in Section 2.4, the requirement of no net increase in pollution load to Deep Bay could not be met even if discharge from the Wo Shang Wai Village is collected for co-treatment. As such, without the proposed interim on-site STP and effluent reuse, occupation of the WSW Development will have to be put on hold indefinitely until public sewerage system is available for connection.
The interim STP and effluent reuse facility are proposed to specifically handle sewage generated from the WSW Development. In order to minimise construction footprint and potential environmental impacts on nearby sensitive uses, the interim STP is proposed to be located within the WSW Development.
Potential Locations within WSW Development
Potential locations for the Project within the WSW Development were primarily identified with the aim of minimising disruption to the development’s master layout plan (MLP). A few potential locations were identified as below and illustrated in Figure 2.1a:
Option 1 – Open space south-west of the WSW Development
Option 2 – Next to WSW site entrance
Option 3 – Near or integrate with the WSW clubhouses
Option 4 – E&M building of WSW Development across the clubhouses next to the development’s boundary fencing
Option 1 is considered to cause the least disruption to the development as no houses or supporting facilities were planned in this area. However, this location is situated in between WSW housing blocks and is anticipated to cause disturbances to nearby residents. Furthermore, area of the site is not sufficient to house the entire STP and effluent reuse facility. In addition, should a structure is constructed to accommodate the STP and associated ventilation facilities, the structure will obstruct the visual and ventilation corridor of the WSW Development, which was an operational phase mitigation measure for landscape and visual impact and was committed by the WSW Development. Therefore, Option 1 is considered not feasible.
An alternative option (Option 2) that would not affect the MLP is to locate the Project near WSW site entrance. However, the ventilation building of the Express Rail Link (XRL) is located adjacent to the WSW site boundary, which already causes fixed noise impact to nearby sensitive receivers. Considering the Project will also generate fixed noise impact, albeit minimal, locating the Project near the entrance is expected to further increase the potential fixed noise impact to nearby sensitive receivers. Furthermore, this location is situated relatively further away from all the residential units of WSW and open space. As reclaimed water has to be fully reused for toilet flushing and irrigation throughout the entire WSW development, locating the STP at the site entrance will require additional effort in conveyance to collect sewage and distribute reclaimed water. Besides, conveyance by gravity may not be feasible and would require mechanical means (e.g., pumps), which would be more energy intensive. To avoid additional noise impacts and energy inefficiency in STP operation, and collection and distribution process, Option 2 was not selected.
The potential of locating the Project near or integration with the WSW clubhouses was also examined (Option 3). This option does not only cause minimal disruption to the MLP, but is also located relatively farther away from sensitive receivers, compared to the above options. Based on latest information available, the E&M facilities supporting the operation of the clubhouses will be accommodated within the clubhouse. Limited space is available for the incorporation of the Project near or within the clubhouses without the need for expanding the premise. According to the approved WSW EIA (AEIAR – 120/2008), the maximum height of buildings within the WSW Development area will be four storeys, to minimise impacts to flight paths of birds. Hence, it is considered to be more appropriate to maintain the form and height of the clubhouse as designed, which will also be compatible with the general character of the area.
The corner near the roundabout of the WSW Development in the east was proposed as an E&M building under the WSW development. This site is considered to be located relatively further from sensitive receivers in comparison to above options (Option 4). This area is also sufficient to house the entire STP and effluent reuse facility. Although this option may be closer to existing residents at Royal Palms when compared to Option 3, the perimeter walls of the WSW development is expected to block the STP structure, and minimise potential noise and visual impact. After careful examination of the affected facilities originally to be housed in the E&M building, it was concluded that relocation of the concerned facilities to the large E&M building near the WSW site entrance was feasible. As such, this is selected as the preferred location considering it will cause the least disruption to the MLP and minimal potential environmental impacts.
Minimal Disturbance to Nearby Existing and Planned Residents
The operation of the Project is expected to cause potential odour, noise and visual impact. As such, minimisation and avoidance of these potential impacts has been considered in deriving the preferred siting and layout of the Project.
Upon confirmation of the site location, due consideration has been given on the layout / setting of the STP and effluent reuse facility. The initial design was to construct an one storey structure at the selected site, with direct connection to the internal driveway leading to the WSW site entrance. However, there are several disadvantages in this:
● The one storey structure will be of medium size, leading to potential greater visual impacts
● Although the transfer, treatment and storage of sewage, sludge and reclaimed water is expected to be confined within the structure, there is yet higher potential for odour impact to nearby sensitive receivers
● Potential noise impact from the operation of STP and tankers transporting sludge offsite
In view of the above, it was decided to place major effluent reuse facilities underground to avoid the aforementioned potential impacts as far as possible. Locating the facilities underground will allow direct connection with the basement carpark of the WSW development. The greatest benefit of this option is the confinement of potential odour impacts from the process of sewage and handling / transportation of sludge. The tankers will be able to transfer all sludge in the basement to minimise the nuisance to the residents.
The STP will be equipped with high-efficiency deodorizer with forced ventilation. Sludge will be directly pumped to the tanker parked at basement / ground floor from the sludge tank or the dewatered sludge will be packed in sealed package / container for off-site disposal. Hence, potential odour nuisance to the carpark is expected to be negligible. Besides, carpark users are not expected to stay within the area for long, potential odour nuisance will be minimal and short-term if any. With the recommended measures to contain potential odour impacts from the STP as detailed in Section 3.6.2, no adverse odour impact to the basement carpark is expected. Furthermore, the aboveground structure will also be of smaller size and thereby minimising potential visual impact.
After due consideration of the above factors, the STP is proposed to be located near the roundabout beside the future clubhouse, as shown in Option 4 of Figure 2.1b. The aforementioned options and their respective environmental benefits and dis-benefits are summarised in Table 2.3 below.
Table 2.3: Summary of Alternative Siting and Layout of the Project
|
Options |
Environmental Benefits |
Environmental Dis-benefits |
|
Option 1 |
● Minimal disturbance to the MLP. |
● Close proximity to sensitive receivers situated in between WSW housing blocks and is anticipated to cause disturbances to nearby residents. ● Obstruction of committed visual and ventilation corridor under the WSW Development. |
|
Option 2 |
● Integration with original E&M buildings and minimise visual impacts. ● Located further away from majority of the sensitive receivers, minimising air and noise impacts. |
● Located far away from sewage collection and reclaimed water distribution, which will require additional pumping facilities and associated infrastructure. Thus, not energy efficient. ● Cumulative noise impacts with XRL’s ventilation building. |
|
Option 3 Near or integrate with WSW clubhouses |
● Avoid potential additional visual impact from a new superstructure. ● Relatively farther away from sensitive receivers. |
● Potential need for expansion of clubhouse footprint to accommodate the STP, potentially affecting the form and height of the clubhouse, which has been designed to be compatible with the character of the area. |
|
E&M building of WSW Development across the clubhouses next to the boundary fencing |
● Some distance from sensitive receivers, but located centrally enough for effective sewage collection and reclaimed water distribution. |
● Additional superstructure with potential visual impacts. |
|
Preferred Option: Option 4 |
||
As the Project falls within the WSW Development, which has already completed site clearance and is in the process of site formation as part of the development’s construction, these works will not be required in this Project.
Other major construction elements will broadly include basement excavation, foundation works, superstructure construction and laying of associated piping network.
The main excavation works required for the Project is the formation of the basement level, at approximately -4.9mPD. There are 2 general approach for excavation, namely bottom up (i.e., open-cut) or top-down. The former approach is the conventional method for excavation and provides easy access for PME and the handling/delivery of materials. However, the bottom up approach requires large construction footprint and the surface can only be restored after completion. Top-down excavation is another common method requiring less construction space and allows other activities to be carried out on the surface simultaneously. Considering the scale of works involved under this Project is relatively small, and both approach utilises similar powered mechanical equipment (PME), the potential environmental impacts associated with either approach would be similar. Furthermore, construction of the Project will be located within the existing construction site of the WSW Development, as such, the potential environmental impact associated with the works footprint for these two approaches is not anticipated to differ greatly.
Regardless of the method to be adopted, all excavated inert materials will be reused on-site as far as practicable or within the WSW Development site.
Foundation and Superstructure
The extent of building structures construction will be minimum. Considering the structure will only consists of basement level and 1-storey above ground, shallow foundations such as strip or pad footings may be adopted. Other common methods for foundations (e.g., large diameter bored piles, pre-bored socket h-piles and driven steel h-piles) are generally for multi-storey buildings requiring large loading capacity and is not considered to be suitable for the Project. Besides, these construction methods generally require larger working areas.
The construction methods for shallow foundation are well established and there are limited alternative options. Minimisation of potential environmental impacts will largely be achieved via application of specific mitigation measures as identified in Section 3 to 8 where applicable.
The superstructure may be constructed by (a) conventional in-situ reinforced concrete; (b) precast concrete; or (c) steelwork construction, largely in the form of prefabricated steelwork elements. The above construction options will not present significant differences in terms of environmental impacts to nearby sensitive receivers. Specific construction methods will be subject to future detailed design. Nevertheless, the superstructure is expected to be of small scale, and the conventional reinforced concrete is likely to be adopted. Should a different form be adopted, it will not present a significant change with regards to environmental impacts.
Percussive piling is not anticipated. However, should percussive piling is eventually required, a Construction Noise Permit will be applied for in accordance with statutory requirements. Non-percussive piling method (e.g. earth auger, mini-pile) is relatively quiet than the percussive piling method as no shocks or vibrations are induced. Given the construction disturbance, non-percussive piling would be adopted.
The piping network for connecting to the effluent reuse facilities will be laid in conjunction with other utilities of WSW Development.
Construction of the Project is targeted to commence in Q3 2018 and complete by 2021 in time for occupation of the WSW Development. The sequence of works will generally follow the order described above, which is common for general building projects, that is excavation, foundation and superstructure works. As the Project is constructed in parallel with the WSW development site to serve the residents in the future, works will be carried out to match the latest WSW development construction programme. The piping network will be constructed together with the network of the WSW development.
The Project will be decommissioned once the planned public sewer on Castle Peak Road is available. However, it is to be noted that the structure of the STP and its associated infrastructure will only cease operation and will not be demolished.
The following major projects under planning and/or construction are likely to interface with the Project:
● Proposed Comprehensive Development at Wo Shang Wai, Yuen Long
● Hong Kong Section of Guangzhou – Shenzhen – Hong Kong Express Rail Link
● The planned Ngau Tam Mei public trunk sewer
● Construction of Cycle Tracks and the associated Supporting Facilities from Sha Po Tsuen to Shek Sheung River
Proposed Comprehensive Development at Wo Shang Wai, Yuen Long
The Proposed Comprehensive Development at Wo Shang Wai is to develop approximately 20.7ha of land in Wo Shang Wai into a residential community in harmony with a wetland restoration area. The proposed STP and effluent reuse facility is to serve this residential community prior to the availability of public sewerage system. The EIA study for this project (AEIAR-120/2008) was approved on 31 July 2008 and construction commenced in 2009. The wetland restoration area has completed construction in 2010 and the residential units are expected to complete for occupation by 2021.
Hong Kong Section of Guangzhou – Shenzhen – Hong Kong Express Rail Link
The Guangzhou-Shenzhen-Hong Kong Express Rail Link (XRL) is a railway service to connect Hong Kong, Shenzhen and Guangzhou via a high speed network from the boundary at Huanggang to West Kowloon Terminus (WKT). It is comprised of an approximately 26km long dedicated underground railway with 8 ventilation buildings, a stabling sidings plus emergency rescue station at Shek Kong. The EIA study for this project (AEIAR-143/2009) was approved on 28 September 2009 and construction commenced in January 2010. One of the eight ventilation buildings is located near the WSW site. According to the latest XRL Newsletter (September 2015), construction is targeted for completion by Q3 2018. Based on the environmental monitoring and audit (EM&A) report for this project and observation from site visits, construction of the Mai Po Ventilation Building has been completed. Therefore, cumulative impacts will be assessed where appropriate.
Ngau Tam Mei Public Trunk Sewer
The planned Ngau Tam Mei public trunk sewer is to provide the trunk sewerage consisting of gravity sewers, rising mains and pumping stations to Ngau Tam Mei / San Tin for the collection and conveyance of sewage generated from Fairview Park and nearby low rise development. The alignment of the proposed trunk sewer falls within the assessment area of the Project, and may have potential cumulative impact. However, based on latest available information, the proposed trunk sewer is currently under planning and design stage and the implementation programme is uncertain. Given the construction programme is unconfirmed and insufficient information is available at this stage, this project cannot be considered as a concurrent project and cumulative impacts will not be assessed.
According to the approved EIA for the project (AEIAR-133/2009), this project is for construction of a new cycle track (with footpath) linking up local cycle track networks in Yuen Long and Sheung Shui. The proposed cycle track will accommodate two-way traffic with minimum width of 3.5m. The associated supporting facilities include five resting stations, one information kiosk and one small seating area which all the facilities will not fall into the assessment area of the Project (i.e. within 500m of the Project boundary). Based on the latest information in EM&A report for the cycle tracks EP (EP-501/2015), the construction work within the assessment area of the Project (i.e. Portion D – Construction of pedestrian ramp) is anticipated to commence in mid-2016 and commission is tentatively in mid-2019. Given the construction works are expected to be small scale, no significant environmental impacts are anticipated during operation phase and the proposed alignment is far away (i.e. more than 300m) from the STP, with the implementation of recommended mitigation measures in the approved EIA report, cumulative impacts will be insignificant and detailed assessment is not required.