7
Sewerage and sewage treatment implications
7.1.1
This
section presents an assessment of the potential sewerage and sewage treatment
implications associated with the operation of the Project. For the construction phase, as the
sewage generated by the workforce can be treated by temporary sewage treatment
facilities (i.e. chemical toilets) provided at construction sites of the
railway line, stations, depot, Emergency Access Point (EAP) / Emergency Egress
Point (EEP) / Ventilation Building (VB), and the temporary magazine site, no
sewerage and sewage treatment implications are identified, and are therefore
not discussed in this section (refer to Section 6 for details). As for the operational phase, the
potential sewerage and sewage implications were identified, and recommendations
for mitigation measures are provided to minimise the
identified sewerage and sewage treatment implications.
7.2.1
The
relevant legislations, standards, and guidelines applicable to this Study for
the assessment of sewerage and sewage implications include:
Ą¤
Environmental Impact Assessment Ordinance (EIAO)
(Cap. 499);
Ą¤
Water Pollution Control Ordinance (Cap. 358);
Ą¤
Sewerage
Manual Part 1 and Part 2, published by Drainage Services Department (DSD); and
Ą¤
Guidelines
for Estimating Sewage Flows for Sewage Infrastructure Planning (Version 1.0)
(Report No.: EPD/TP 1/05), published by Environmental
Protection Department (EPD).
7.2.2
The
EIAO (Cap. 499) provides the major statutory framework for the environmental
impact assessment in Hong Kong. Under Section 16 of the EIAO,
Environmental Protection Department (EPD) issued the Technical Memorandum on
Environmental Impact Assessment Process (EIAO-TM) which specifies the
assessment methods and criteria for the EIA. The sewerage and sewage
treatment implications are assessed according to Annexes 6 and 14 of the
EIAO-TM, which stipulates the Ą°Criteria for Evaluating Water PollutionĄą and Ą°Guidelines
for Assessment of Water PollutionĄą respectively.
7.2.3
WPCO
(Cap. 358) provides the major statutory framework for the protection and
control of water quality in Hong Kong.
According to the Ordinance and its subsidiary legislation, the entire
Hong Kong waters are divided into ten Water Control Zones (WCZs) and four
supplementary WCZs. Each WCZ has a
designated set of statutory Water Quality Objectives (WQOs). The WQOs set
limits for different parameters that should be achieved to protect specific
beneficial uses and conservation goals of each of the zones. The ProjectĄ¯s assessment area falls
under the Deep Bay WCZ.
7.2.4
DSDĄ¯s
Sewerage Manual provides guidelines on the planning, design, construction,
operation, and maintenance of the public sewerage systems in Hong Kong. The manual is divided into two parts. Part 1 of the manual provides guidelines
regarding public gravity sewerage systems in Hong Kong, whereas Part 2 of the
manual provides guidelines regarding sewage pumping stations and rising mains.
7.2.5
EPDĄ¯s
Guidelines for Estimating Sewage Flows (GESF) provides guidance on good
practices for estimating sewage flows for planning catchment level and
sub-catchment level sewage infrastructure.
The application of the GESF to planning sub-catchment local sewage
infrastructure would involve deliberation of the worst-case scenarios of usages
and populations of the existing and proposed developments.
7.3
Existing and Planned
Conditions
General
7.3.1
The
vicinity of the works sites is mostly unsewered rural land, except for areas in
Kam Tin. Existing sewerage systems are
only identified near Kam Sheung Road and Au Tau. These existing sewerage systems are
conveying sewage via Kam Tin Sewage Pumping Station (SPS) and Sha Po SPS to the
existing Yuen Long Sewage Treatment Works (YL STW). The Existing YL STW is currently being
upgraded to the Yuen Long Effluent Polishing Plant (YL EPP).
7.3.2
Planned
sewerage systems in Kam Tin South, Sha Po, Ngau Tam Mei, San Tin and Kwu Tung North are also identified.
7.3.3
Existing
sewerage key plans and layout plans for Northern Link (NOL) are shown in Figure Nos. C1603/C/NOL/ACM/M54/301 to 311.
KSR(NOL)
Station
7.3.4
An
existing sewerage system was identified along the southern and western sides of
KSR(TML) Station, with pipelines ranging from 225mm to 450mm in diameter. An existing Sewage Holding Tank No. 2
located underground was also identified, which is planned to be demolished.
Sewage will be diverted to the planned public sewerage systems.
7.3.5
Planned sewerage system was identified for Kam Tin South Housing Development.
Kam
Sheung Road (KSR) to Au Tau (AUT) Stations
7.3.6
A
section of existing private 600mm diameter sewerage pipe along Shui Mei Road,
at the south of Park Yoho Phase 1 near Shui Mei Road Ancillary Building was
identified above the bored tunnels.
Au Tau
(AUT) Station
7.3.7
The
existing Sha Po SPS and associated sewerage system were identified at the
south-west corner of AUT Station.
7.3.8
Planned
sewerage system was identified for Sha Po Public Housing Development.
Au Tau
(AUT) to Ngau Tam Mei (NTM) Stations
7.3.9
No
existing nor planned public sewerage systems in the vicinity were identified in
this area.
Ngau Tam
Mei (NTM) Station and Ngau Tam Mei Depot (NTD)
7.3.10
The
existing Ngau Tam Mei area is an unsewered land. No existing public sewerage system in
the vicinity was identified in this area.
7.3.11
CEDD
commissioned a land use review feasibility study of Ngau Tam Mei Area Land Use
Review (NTM LUR) in November 2021, both NTM Station and NTD are within the
study area of NTM LUR. The planned
sewerage system will be developed under the NTM LUR project and further liaison
with CEDD regarding the sewerage connection will be conducted.
Ngau
Tam Mei (NTM) to San Tin (SAT) Stations
7.3.12
There
were 2 nos. of private sewage treatment plants near the Vineyards and the Tam
Mei Barrack identified in this area.
San
Tin (SAT) Station
7.3.13
The
existing San Tin area is an unsewered land. No existing public sewerage system in
the vicinity was identified in this area.
7.3.14
CEDD
commissioned an investigation study on the Development of the San Tin / Lok Ma
Chau Development Node (STLMC DN) in October 2021, a planned sewerage system
would be proposed for STLMC DN.
Further liaison is required for the planned drainage and sewerage
network in the vicinity of SAT Station.
San
Tin (SAT) to Kwu Tung (KTU) Stations
7.3.15 Existing SAT to KTU areas are unsewered land.
No existing public sewerage system in the vicinity was identified in
this area.
Kwu Tung
(KTU) Station
7.3.17
KTU Station is located within the KTN NDA boundary
under Agreement No. 13/2014 (CE) Development of Kwu
Tung North and Fanling North New Development Areas,
Phase 1 ¨C Design and Construction (KTN NDA Advanced Phase) and Agreement No. CE
19/2019 (CE) Development of Kwu Tung North New
Development Area, Remaining Phase ¨C Design and Construction (KTN NDA Remaining
Phase), of which the construction would be completed by 2025/2026 and 2031
tentatively.
7.3.18
By
the time of KTU(EAL) StationĄ¯s opening, infrastructure works under KTN NDA
Advanced Phase would be completed.
However, these sewerage provisions do not cover the whole site for KTU
Station and terminate at the west of the station. In addition, the invert level of the
nearest sewage manhole is above the site formation level of KTU Station, hence
interim sewage networks are proposed at KTU Station.
Existing and Planned Sewage Treatment
Works and Sewage Pumping Stations
7.3.19
According
to the information provided by DSD, the existing and planned STW and SPS
closest to the Project include:
Ą¤
Shek Wu Hui STW (SWH STW);
Ą¤
Yuen Long STW (YL STW);
Ą¤
Kam Tin SPS;
Ą¤
Sha Po SPS;
Ą¤
Nam Sang Wai SPS; and
Ą¤
Proposed Kwu Tung North
SPS.
7.3.20
The
existing SWH STW is a secondary treatment works which collects and treats the
sewage generated from Fanling/Sheung Shui and other
areas before discharging into Deep Bay through Ng Tung River and Shenzhen
River, and the average daily flow in 2022 at SWH STW is approximately
93,840m³/day. The capacity of the
existing SWH STW is 105,000m³/day and the designed capacity will be 190,000
m³/day being upgraded to the Shek Wu Hui Effluent Polishing Plant (SWH EPP),
with the completion date planned to be Year 2034.
7.3.21
The
existing YL STW is a secondary treatment works with a designed capacity of
35,000m³/day, collecting sewage from Yuen Long. The averaged daily flow in 2022
is approximately 26,750m3/day.
According to EIA for Yuen Long Effluent Polishing Plant (Register No.:
AEIAR-220/2019), YL STW will be upgraded to the Yuen Long Effluent Polishing
Plant (YL EPP), and it will be constructed in two phases. Phase 1 works will upgrade the existing
YL STW into YL EPP with a treatment capacity of 100,000 m³/day in Average Dry
Weather Flow (ADWF). As advised by
EPD, Phase 2 works will be implemented subject to further review of sewage flow
projections and will further upgrade the treatment capacity to 150,000 m3/day.
7.3.22
The
existing Kam Tin SPS is a sewage pumping station with a designed capacity of
17,133m³/day, collecting sewage from Kam Tin area and directing it to the YL
STW for treatment. The averaged
daily flow in 2022 is approximately 2,480m³/day, and the planned Kam Tin South
Development will generate an approximated ADWF of 13,000m³/day, which is within
the designed capacity.
7.3.23
The
existing Sha Po SPS is a sewage pumping station with a designed capacity of
8,795m³/day, it directs sewage to the YL STW for treatment, the averaged daily flow in 2022 is approximately
1,370m³/day. The planned Sha Po
Public Housing Development will generate an approximated ADWF of
13,200m³/day. The SPS is planned to
be upgraded to a capacity of 16,750m³/day for the Sha Po Public Housing
Development.
7.3.25
The
Proposed Kwu Tung North SPS will be constructed under
KTN NDA, which has a planned ADWF of 56,215m³/day.
7.4
Assessment Methodology
General
7.4.1
The
major wastewater sources generated by the Project include the sewerage from the staff, commercial activities and passengers, and
Ancillary Building Wastewater as listed below:
Ą¤
Rainfall blown into railway louvre openings;
Ą¤
Groundwater seepage;
Ą¤
Discharge from tests on the fire system;
Ą¤
Leakage from services; and
Ą¤
Condensation from E&M equipment.
Sewage from Commercial
Activities, Staff, and Passengers
7.4.2
The
assessment was out in accordance with the guidelines set out in Report No.:
EPD/TP 1/05 Guidelines for Estimating Sewage Flows for Sewage Infrastructure
Planning Version 1.0 and the Sewerage Manual published by DSD.
7.4.3
The
methodology for flow estimation is based on the following steps:
Ą¤
Identify
the scope of the Project;
Ą¤
Determine
the sewage generation from the Project;
Ą¤
Identify
the existing and planned sewerage systems within and in the vicinity of the
proposed Project boundary;
Ą¤
Examine
the impact arising from new sewage generation from the Project on the existing
sewage conveyance, pumping stations and treatment systems; and
Ą¤
Identify
new and upgrading sewerage works.
Unit Flow Factors - Commercial Flows
7.4.4
Commercial
flows comprise flows from the employee and commercial activities which contains
11 job categories as classified in GESF.
The unit flow factors of commercial flows are shown in Table 7.1.
Table
7.1 Population
Factor and Unit Flow Factor for Non-Station Lobby Areas
|
Floor Uses
|
Population Factor
|
Category
|
Unit Flow Factor(1)
(m3/head/day)
|
|
Non-public
E&M Rooms
|
35(2)
|
m2/worker
|
J2
Electricity, Gas & Water
|
0.33
|
|
Concession (Retail Area)
|
25(2)
|
m2/worker
|
J4 Wholesale & Retail
|
0.28
|
|
Concession (Food & Beverage)
|
5.1(3)
|
Worker/100m2
|
J10 Restaurants & Hotels
|
1.58
|
|
Non-public Operation Room
|
25(2)
|
m2/worker
|
Territorial Average
|
0.28
|
Notes:
(1)
Table T2 of Guidelines for Estimating Sewage Flows for Sewage
Infrastructure Planning Version 1.0 (Report No. EPD/TP 1/05) refers.
(2)
Table 2 of Chapter 5 of the Hong Kong Planning Standards and
Guidelines published by the Planning Department.
(3)
Figure 9 of Commercial and Industrial Floor Space Utilization
Survey published by the Planning Department.
Peaking Factors
7.4.5
The
Peaking Factor (P) was used to determine peak flows which are flows resulting
from a combination of factors including diurnal and seasonal flow variations of
flow components and characteristic response of inflow and base flows to storm
events. Peak flows could be
determined from peaking factors and adequate safety margins could be provided
during the planning of sewerage facilities. The Peaking Factors adopted for this
assessment are listed under Table 7.2 below.
Table 7.2 Peaking Factors
|
Population Range
|
Peaking Factor (including stormwater allowance) for facility
with existing upstream sewerage
|
Peaking Factor (excluding stormwater allowance) for facility
with new upstream sewerage
|
|
a) For sewers
|
|
<1,000
|
8
|
6
|
|
1,000 - 5,000
|
6
|
5
|
|
5,000 - 10,000
|
5
|
4
|
|
10,000 - 50,000
|
4
|
3
|
|
> 50,000
|
Max
(7.3/N0.15, 2.4) (1)
|
Max
(6/N0.175, 1.6) (1)
|
|
b) Sewage Treatment Works, Preliminary Treatment Works and Pumping
Station
|
|
<10,000
|
4
|
3
|
|
10,000 - 25,000
|
3.5
|
2.5
|
|
25,000 - 50,000
|
3
|
2
|
|
> 50,000
|
Max
(3.9/N0.065, 2.4) (1)
|
Max
(2.6/N0.065, 1.6) (1)
|
Note:
(1) N is the contributing population in
thousands, where contributing population is the calculated total average flow /
0.27 m3/person/day.
Catchment Inflow Factors
7.4.6
Catchment
Inflow Factors (PCIF) such as infiltration of water or sewage are
not considered relevant in the estimation of planned sewerage flows. PCIF was therefore not
considered to be applicable to new sewerage systems, and a factor of 1 was
applied. According to Table T-4 in GESF, a PCIF of 1 was adopted.
Discharge Unit Method
7.4.7
Sewage
from public toilets within the stations are estimated based on the Ą°Discharge
Unit (DU) MethodĄą with reference to the Chartered Institute of Plumbing and
Heating Engineering (CIPHE)Ą¯s Plumbing Engineering Services Design Guide. The
adopted DU are in Table 7.3 while K refers to Frequency of Use Ą°K
FactorĄą as listed in Table 7.4.
Table 7.3
Discharge Units for Sanitary Fitments
|
Appliances
|
Discharge Units (L/s)
|
|
Wash Basin
|
0.3
|
|
Urinals with Basin
|
0.4
|
|
Washing Closet with 6L Cistern
|
1.5
|
|
Shower
|
0.5
|
|
Cleaner's Sink
|
0.3
|
|
Cleansing Point
|
0.5
|
Table 7.4
Frequency of Use ĄŽK FactorĄ¯
|
Usage of Appliance
|
Frequency of Use ĄŽK
FactorĄ¯
|
|
Intermittent Use (e.g.
dwelling, guesthouse, office etc.)
|
0.5
|
|
Frequent Use (e.g.
hotel, restaurant, school, hospital etc.)
|
0.7
|
|
Congested Use (e.g.
toilets and/or showers open to the public etc.)
|
1.0
|
|
Special use (e.g. laboratories etc.)
|
1.2
|
7.4.8
The
Ą°K factorĄą of 1.0 is deemed most appropriate for the proposed rail stations and
was therefore adopted for sewage flow estimations.
7.5
Sewage Flow Estimation
7.5.2
Method
(i) estimates the peak flow rate discharged into
terminal manholes/sewerage holding tanks, which is the sum of the full load of
sump pump flow rate, plus discharge flow from internal gravity sewerage system,
if applicable. Therefore, Method (i) is considering
the peak flows under an extreme case.
7.5.3
Method
(ii) estimates the sewage flow rate through a summation of the population based
daily sewage discharge calculated by EPDĄ¯s GESF method and daily sanitary
fitment discharge calculated by CIPHEĄ¯s ĄŽDischarge Unit MethodĄ¯. Therefore,
Method (ii) is considering the case under normal operation.
Sewage Flow Estimation for Depot, Stations, Ancillary
Buildings
7.5.4
For
Method (i), the detailed breakdown of peak sewage
peak flows by adopting pump flow rate and maximum sanitary fitment discharge
are shown in Appendix 7.1. For Method (ii), the daily
sewage flow and peak flow calculations adopting sewage discharge rate according
to EPDĄ¯s GESF and CIPHEĄ¯s ĄŽDischarge Unit MethodĄ¯ are shown in Appendix 7.2.
7.5.5
The
adopted sewage peak flow estimated for depot, stations and ancillary buildings
using Method (i) are summarised
in Table 7.5 below.
Table
7.5
Method (i) - Summary of Adopted Sewage Peak
Flow
|
Location
|
Adopted Peak Flow (L/s)
|
|
KSR(NOL) Station(1)
|
187.0
|
|
AUT Station(1)
|
176.5
|
|
NTM Station(1)
|
88.0
|
|
NTD(1)
|
261.6
|
|
SAT Station(1)
|
186.0
|
|
KTU(NOL) Station(1)
|
24.0
|
|
Shui Mei Road Ancillary Building (SMA)
|
24.0
|
|
Pok Wai Ancillary Building (PWA)
|
24.0
|
|
Long Ha Tsuen Ancillary Building (LHA)
|
24.0
|
|
San Tin Ancillary Building (SNA)
|
60.0
|
|
Ka Lung Road Ancillary Building (KLA)
|
24.0
|
|
Kwu Tung Road Ancillary Building (KTA)
|
24.0
|
|
Pak Shek Au Ancillary Building (PAA)
|
24.0
|
Note:
(1)
Tunnel sewage has been included in the station flow.
7.5.6
For
Method (ii), the daily sewage flow was estimated through the summation of EPDĄ¯s
GESF method and CIPHEĄ¯s ĄŽDischarge Unit MethodĄ¯. A peaking factor for sewers of
6 was adopted to estimate the sewage peak flow of Method (ii) for EPDĄ¯s GESF
method. The summary of the extracted and adopted sewage peak flows and ADWF of
the mentioned locations are presented in Table 7.6. The values are presented for comparison only, and will not be adopted in the sewerage network
design.
Table
7.6
Method (ii) ¨C Summary of Adopted Sewage Peak Flow
|
Location
|
Adopted Peak Flow (L/s)
|
ADWF
(m3/day)
|
|
KSR(NOL) Station
|
57.4
|
256.9
|
|
AUT Station
|
47.2
|
204.0
|
|
NTM Station
|
50.2
|
210.9
|
|
NTD
|
75.8
|
247.7
|
|
SAT Station
|
59.3
|
236.3
|
|
KTU(NOL) Station
|
7.3
|
86.2
|
|
Shui Mei Road Ancillary Building (SMA)
|
9.7
|
15.1
|
|
Pok Wai Ancillary Building (PWA)
|
10.7
|
15.4
|
|
Long Ha Tsuen Ancillary Building (LHA)
|
7.4
|
8.7
|
|
San Tin Ancillary Building (SNA)
|
14.8
|
47.0
|
|
Ka Lung Road Ancillary Building (KLA)
|
13.3
|
25.4
|
|
Kwu Tung Road Ancillary Building (KTA)
|
15.2
|
44.8
|
|
Pak Shek Au Ancillary Building (PAA)
|
11.8
|
24.9
|
7.5.7
To
summarise, the peak flow rate estimated under
Method (i) represents the maximum sewage flow received
by terminal manholes/sewage holding tanks under extreme/emergency scenarios.
Whereas the daily flow rate estimated through Method (ii) estimates the sewage
flow rate generated under normal daily operations of NOL.
7.5.8
The
total peak flow generated from this Project estimated from Method (i) is 1,127.1 L/s (including 923.1 L/s from stations and
depot, and 204.0 L/s from ancillary buildings). Whereas the averaged dry
weather flow generated under normal daily operations of NOL estimated from
Method (ii) is 1,466.5 m3/day.
Sewage
Flow Estimation for Track Washdown Water
7.5.9
Track
washdown water is allowed in the proposed sewerage network, which is a maximum
of 25,000L spread evenly over 1km of tracks per 1 hour. When assuming a 2km section of single
track is washed within 1 hour, the contribution of track washdown water would
be 14L/s.
7.5.10
The
proposed rail alignment would be tunneled. The track washdown water will then
be conveyed by tunnel sewerage system, and ultimately discharge to stations via
internal sewage pumping system.
Cumulative Impacts and Proposed
Sewerage Network
7.5.11
To
determine the connection arrangement to the public sewerage system, the
cumulative sewage flow with the interfacing projects were estimated to check
whether the capacity is sufficient.
As part of the Project areas (i.e., NTM, SAT, and KTU Stations) fall
into the planned development areas of the Northern Metropolis, new public
sewerage networks are anticipated for the new town developments including the
stations. A list of interfacing
projects is shown in Table 7.7.
Table 7.7 Planned Project and Development
Time Frame
|
Planned Project /
Development
|
Time Frame
|
|
Kam Tin South Public Housing Development
|
Completion years for Site 1
Phase 1: 2027/2028
Phase 2: 2027
Completion years for Site 4A
Phase 1: 2028
Phase 2: 2028
Phase 3: 2030
Completion years for Site 6
Phase 1: 2027
Phase 2: 2028
|
|
Kam Sheung Road Package 2 Property Development
|
Under planning
|
|
Park Yoho Phase 2 & 3 Development
|
Under planning
|
|
Sha Po Public Housing Development
|
Completion year: 2031
|
|
Land Use Review Study for Ngau Tam Mei Area
|
Under planning
|
|
San Tin Lok Ma Chau Development Node
|
Completion year: 2034
|
|
Kwu Tung North New Development Area
|
Advance works completion year: 2026
Remaining phase completion year: 2031
|
7.6
Proposed Sewerage Connections
Table
7.8
Proposed Sewerage Connection and Treatment Locations
|
Locations
|
Proposed Sewerage Connection Location
|
Proposed Sewage Treatment Location
|
|
KSR(NOL) Station
|
Planned KTS Sewerage System
|
Planned YL EPP via existing Kam Tin SPS
|
|
AUT Station
|
Planned Sha Po Sewerage System
|
Planned YL EPP via existing / planned Sha Po SPS
|
|
NTM Station
|
Proposed Temporary Sewage Holding Tank / Planned NTM LUR Sewerage System
|
Tanker away by MTRCLĄ¯s competent contractor(2)
/ TBC by NTM LUR(1)
|
|
NTD
|
Proposed Temporary Sewage Holding Tank / Planned NTM LUR Sewerage System
|
Tanker away by MTRCLĄ¯s competent contractor(2)
/ TBC by NTM LUR (1)
|
|
SAT Station
|
Planned STLMC DN Sewerage System
|
Planned STLMC EPP
|
|
KTU(NOL) Station
|
Planned KTN NDA Sewerage System
|
Planned SWH EPP via Planned KTN SPS
|
|
Shui Mei Road Ancillary Building (SMA)
|
Proposed Sewerage Holding Tank
|
Tanker away by MTRCLĄ¯s competent contractor(2)
|
|
Pok Wai Ancillary Building (PWA)
|
Proposed Sewerage Holding Tank
|
Tanker away by MTRCLĄ¯s competent contractor(2)
|
|
Long Ha Tsuen Ancillary Building (LHA)
|
Proposed Sewerage Holding Tank
|
Tanker away by MTRCLĄ¯s competent contractor(2)
|
|
San Tin Ancillary Building (SNA)
|
Planned STLMC DN Sewerage System
|
Planned STLMC EPP
|
|
Ka Lung Road Ancillary Building (KLA)
|
Proposed Temporary Sewage Holding Tank / Planned STLMC DN Sewerage System
|
Tanker away by MTRCLĄ¯s competent contractor(2)
/ Planned STLMC EPP
|
|
Kwu Tung Road Ancillary Building (KTA)
|
Proposed Temporary Sewage Holding Tank / Planned STLMC DN Sewerage System
|
Tanker away by MTRCLĄ¯s competent contractor(2)
/ Planned STLMC EPP
|
|
Pak Shek Au Ancillary Building (PAA)
|
Proposed Temporary Sewage Holding Tank / Planned STLMC DN Sewerage System or Planned
KTN NDA Sewerage System
|
Tanker away by MTRCLĄ¯s competent contractor(2)
/ Planned SWH EPP via
Planned KTN SPS
|
Notes:
(1)
TBC = to be confirmed.
(2) The tanker away method should be similar to that adopted by the
existing Pat Heung Depot.
7.7
Proposed
Sewerage Arrangement at Specific Locations
7.7.1
The
proposed sewerage key plan and layout plans are shown in Figure Nos. C1603/C/NOL/ACM/M54/301 to 311.
KSR(NOL) Station
7.7.2
The
sewage generated at KSR(NOL) Station is proposed to be conveyed by gravity
sewers towards the middle and northern ends of the station. Sewage terminal manholes and public
sewerages are proposed for the connection to Kam Tin South planned sewerage
network, which will then convey sewage to Kam Tin SPS before ultimately
discharged to the planned YL EPP.
AUT Station
7.7.3
The
sewage generated at AUT Station is proposed to be conveyed by gravity sewers
towards the southern end of the station.
Sewage terminal manholes with public sewerages are proposed for
connection to the planned sewerage network of Sha Po Public Housing
Development, which will then be connected to the Sha Po SPS before being
ultimately discharged to the planned YL EPP.
NTM Station and NTD
7.7.4
The sewage generated at NTM Station is proposed to be
conveyed by the proposed internal gravity
sewers towards the northern end of station and discharge to the proposed sewage
terminal manholes. Proposed sewage
generated at NTD will also be conveyed by the proposed internal sewerage network and discharged to the
proposed sewage terminal manhole.
Sewage generated at both NTM Station and NTD will be conveyed to the public sewers at the
northeastern end, and a sewer plug end is proposed for connection to the NTM
LUR planned sewerage network. The
sewage would be ultimately discharged to the Planned STLMC EPP via NTM SPS. Temporary sewage arrangements at both NTM Station and NTD would be
required.
SAT Station
7.7.5
The
sewage generated at SAT Station is proposed to be conveyed by gravity
sewers. It is proposed that a
sewage terminal manhole with sewer plug ends should be connected the sewerage
system of the planned STLMC DN, with the sewage ultimately discharged to the
planned STLMC EPP.
KTU Station
7.7.6
The
sewage generated at KTU Station is proposed to be conveyed by gravity
sewers. It is proposed that a sewage
terminal manhole with sewer plug ends should be connected the sewerage system
of the planned KTN NDA, with the sewage connected ultimately to the planned SWH
EPP.
7.7.7
Provisions
for connection from KTU(NOL) Station are reserved at the sewerage system
constructed with KTU(EAL) Station and it is designed to cater for KTU (NOL)
Station development. The interim
sewerage arrangements would be decommissioned by the time of KTU(NOL) Station
opening.
Tunnel Sewage
7.7.8
The
foul water accumulated at the foul water line sumps in railway tunnels will be
pumped to nearby stations for collection and eventual discharge into the public
sewerage system.
Ancillary
Buildings
7.7.9
For
ancillary buildings including SMA, PWA, and LHA, due to the unavailability of
existing public and planned sewer nearby, discharge generated from toilets and
washdown sanitary fitments will be collected in sewage holding tanks located at
ground level. The sewage will then
be tankered away by competent contractors
regularly. Sewage plug ends were
proposed in the design of these ancillary buildings in case of future
connections.
Ventilation Buildings
7.7.11
For
ancillary buildings containing ventilation buildings (i.e.
SMA, PWA, SNA and KTA), discharge from toilets and washdown sanitary fitments
will be discharged by gravity sewers to a sump pit located at the track
level. The sewage will then be
collected and transferred via sump pumps to a foul water terminal manhole at
ground level, before being connected to sewage holding tanks for further
connection to the public sewer system or tankered
away by competent contractors. Vent
pipes will be connected to all traps of water closets and urinals, which will
then be connected to a common vent stack and will be discharged to the open
space located above ground level.
7.7.12
For
surface wastewater sewerage system, discharges from floor drains will be
connected to the sump pit at track level via gravity sewers. The discharges will be then collected
and lifted by sump pumps to an oil interceptor at ground level before being
discharged to a foul water terminal manhole.
Temporary
Sewerage Arrangements
7.7.13
All
sewages generated at different locations of the Project will be collected by
public sewerage treatments and directed to EPPs for treatment (unless
specifically stated otherwise).
However, in case that the municipal sewerage systems for the new town
developments and along the NOL alignment by DSD were not in commission before
the Project (i.e. Year 2034), the effluent generated
from the Project would be collected in temporary sewage holding tanks at ground
level, which will be tankered away for off-site
disposals. Provision of plug end
would be allowed in the temporary sewerage system for future connections to the
public sewerage system. Only the NTM
Station, NTD, KLA, KTA, and PAA would require temporary sewerage arrangements.
7.7.14
Considering
that some planned stations, depot and ancillary buildings (i.e., NTM Station, NTD, and ancillary buildings
listed under Section 7.7.10) are located at more than 2km away from existing public sewers, and that
the commissioning time between the stations and their respective interfacing
developments are less than 2 years, as listed in Table 7.7 above, the
timeframe requiring temporary sewerage arrangements would be relatively short,
and hence it would not be practical to construct a sewerage network just to
cater for the Project.
7.7.15
The
tanker away frequencies under normal operation (proposed that 15m3
tank trucks will be deployed) for NTM Station and NTD will be approximately 14
and 17 times daily respectively, before public sewerage system is available for
connection. Sewage generation at
SMA, PWA, and LHA would be very minimal as these ancillary buildings are mainly
used by MTR staff. Tanker away
frequency is expected to be once to twice per a month.
7.7.16
It
is unlikely that temporary sewage arrangements will be provided for SAT Station
and SNA, as the planned sewerage networks of STLMC DN will be available near
the commissioning time of these facilities. However, in case of programme mismatch, it is recommended that tanker away by a
competent registered contractor at the designated disposal location should be
arranged as a temporary mitigation measure to dispose of sewage generated at
these locations.
7.7.17
Tanker
away arrangement will be carried out by competent registered contractor and
disposed the connected sewage at designated disposal locations to be further
advised by DSD after further liaison on tanker away arrangement.
Interim Discharge of Effluent
7.7.18
All
sewage generated would either be discharged to the planned SWH EPP, planned YL EPP, and planned STLMC EPP
for treatment, or tankered away regularly by
competent contractors for off-site disposal. Hence, no interim discharge of
effluent is anticipated.
7.8 Demarcation of Maintenance
Responsibilities
7.8.1
Table 7.9 lists out the demarcation of the maintenance responsibilities for the
various proposed sewerage facilities.
Table 7.9 Proposed Demarcation of Maintenance
Responsibilities
|
Description
|
Proposed Works Agent
|
Proposed Maintenance Agent
|
|
Proposed Sewers and Manholes up to Terminal
Manholes
|
MTR Corporation
|
MTR Corporation
|
|
Proposed Sewers and Manholes beyond Terminal
Manholes
|
MTR Corporation
|
DSD
|
7.9
Potential Sewerage Impacts and
Proposed Mitigation Measures
Sewerage Impact
7.9.1
In this Project, sewage
generated will be discharged to the planned SWH EPP, planned YL EPP, and
planned STLMC EPP, except for satellite locations and temporary arrangements.
The planned EPPs will have a sufficient capacity to handle the sewage load generated
by this Project. For locations where there are unavailable existing or planned
public sewerage systems nearby, sewage will be tankered
away regularly by competent contractors.
7.9.2
Planned sewerage systems
located in Kam Tin South, Sha Po, Ngau Tam Mei, San Tin, and Kwu Tung North were also identified, which have considered
and incorporated the proposed sewage load generated by this Project in their
designs.
7.9.3
For
existing public sewerage systems, there is sufficient capability to handle the
additional sewage load generated by the Project. As for the planned public sewerage systems,
the additional sewage load generated by the Project has been accounted for by
the interfacing projects (i.e. Kam Tin South, Sha Po,
NTM LUR, STLMC DN, and KTN NDA), any planned upgrades have been incorporated in
their respective assessments, and thus the planned public sewerage systems will
have sufficient capacity to handle the additional sewage load generated by this
Project.
Proposed Mitigation
Measures
7.9.4
Considering that the
existing and planned sewage load can be sufficiently handled by both existing
and planned public sewerage systems, it is anticipated that there would be no
unacceptable adverse impact on the sewerage systems arising from the operation
of the Project. Hence, no
mitigation measures are required.
7.10.1 The implications of potential impacts on the existing public sewerage
system from the potential sewage generated by the Project was assessed.
7.10.2 The Project is located within the existing Yuen Long sewerage catchment
and the planned STLMC DN sewerage catchment. Existing sewerage systems were only
identified in the vicinity of KSR(NOL) and AUT Stations. Planned sewerage systems in Kam Tin
South, Sha Po, Ngau Tam Mei, San Tin and Kwu Tung
North were also identified. All the
sewage generated by this Project will be discharged to MTRCLĄ¯s Sewage Holding
Tanks, planned SWH EPP, planned YL EPP, and planned STLMC EPP for treatment,
except for satellite locations and temporary arrangements.
7.10.3 The proposed sewers will be generally connected to nearby existing or
planned sewerage systems via the proposed terminal manholes to minimise the construction implications.
7.10.4 It is anticipated that there would be no adverse impacts to the existing
and planned sewerage system due to the Project.
7.10.5 Analysis of planned sewer usage for connection will be updated when
further information is available.
Upgrade of planned sewers may be required subject to further assessment. Further liaison with Kwu
Tung North New Development Area, Kam Tin South Public Housing Development, Sha
Po Public Housing Development, Ngau Tam Mei Area Land Use Review and San Tin /
Lok Ma Chau Development Node is required for the proper arrangement of sewerage
interfaces.