7
sewerage
and sewage treatment implications
7.1.1
The proposed development
scheme at SHR Site, SHR Site Extension and HPR Site will generate large amount
of sewage flows due to the population and employment intake. The expected
impact/ implication on the existing and planned sewage systems and the
proposals of sewerage infrastructure and mitigation measures to support the
proposed development are discussed in this chapter.
7.2.1
The following established
guidelines and standards are adopted for sewage flow estimation, assessment and
evaluation of sewerage and sewage treatment implications of the Project:
·
DSD Sewerage Manual Part 1 (2013 Version);
·
DSD Sewerage Manual Part 2 (2013 Version);
·
DSD Technical Circulars and Practice Notes;
·
EPD Guideline for Estimating Sewage Flows (GESF)
for Sewage Infrastructure Planning Version 1.0 (Report No. EPD/TP 1/05); and
·
Environmental Impact Assessment Ordinance
(EIAO), Technical Memorandum on Environmental Impact Assessment Process
(EIAO-TM), Annex 14 Section 6.5.
Record Plans and Drainage As-built Drawings
7.3.1
Record plans and as-built
drawings of the existing sewerage in the vicinity of the Sites were obtained
from Mainland North Division of Drainage Services Department (DSD). The information is adopted to assess the
potential sewerage impact arising from the Development under this assignment.
Review On Relevant Completed, Current
and Planned Sewerage Projects
7.3.2
Several completed, ongoing
and planned sewerage projects are being implemented in the Tuen
Mun sewage catchment, as listed below:
·
Contract No. DC/2009/11 – Tuen Mun Western Trunk Sewerage (Western
Interceptor Sewer)
·
Contract No. DC/2010/01 – Tuen Mun Village Sewerage and Trunk Sewers at
Pillar Point
·
PWP No. 4374DS – Tuen Mun Sewerage, Stage 1 – Village Sewerage
in Tsing Chuen Wai and Tuen
Tsz Wai (part)
7.3.3
Relevant projects are
discussed as follows:
PWP No. 4346DS – Upgrading of Tuen Mun Sewerage, Phase 1
PWP No. 4160DS - Tuen
Mun Sewerage, Stage 1
7.3.4
The project aims at
providing village sewerage in Tuen Mun and constructing
new trunk sewerage in Tuen Mun Siu Lam area and Tuen Mun North in order to improve the sanitary condition
to cater for the planned and forecast development.
7.3.5
Tsz Tin Tsuen, Po Tong Ha,
Siu Hang Tsuen and Kei Lung Wai are planned with sewerage provision for
discharge to TM54 SPS. The proposed
sewerage works are tentatively scheduled to commence in Q1 2021 for completion
in Q4 2024.
PWP No. 4329DS – Upgrading of Pillar Point
Sewage Treatment Works
7.3.6
The project aims to
upgrade the sewage treatment level of the Pillar Point Sewage Treatment Works
(STW) from preliminary treatment to chemically enhanced primary treatment with
disinfection along with an expansion of the treatment capacity from 215,000 m3/day
to 241,000 m3/day [Average dry weather flow (ADWF)]. This Project was completed in 2014.
PWP No. 4371DS – Sewerage in Western Tuen Mun
7.3.7
The project aims to provide new trunk
sewerage in Tuen Mun West and improve the sanitary
condition to cater for the planned and forecast development. The project comprises the design and
construction of the 1,800mm diameter Western Interceptor Sewer (WIS) along Ming
Kum Road for conveying the sewage flow to the WIS SPS and subsequently to the
Pillar Point STW. This Project was completed in 2016.
PWP No. 4374DS – Tuen
Mun Sewerage, Stage 1 – Village Sewerage in Tsing Chuen
Wai and Tuen Tsz Wai
7.3.8
The project aims at providing public
sewerage to Tsing Chuen Wai and Tuen
Tsz Wai in Tuen Mun so as to improve the water
quality in nearby watercourses and Tuen Mun River
Channel as well as the sanitary conditions of these unsewered
village/areas. The project comprises the
construction of about 1.5km of sewers to serve part of the areas of Tsing Chuen Wai and Tuen Tsz Wai in Tuen Mun.
7.4.1
After commissioning of the WIS, sewage in the Tuen Mun catchment would ultimately discharge to the Pillar
Point STW via two routes, as discussed below and presented in Figure 7.1:
·
Sewage generated from the northern Tuen Mun catchment would convey to the proposed TM54 SPS for discharge to the WIS at Ming Kum
Road and subsequently to the Pillar Point STW.
·
Sewage generated from the northeastern and eastern Tuen Mun
catchment would convey to Siu Hong Road SPS,
subsequently to Pak Kok SPS for discharge to the
Pillar Point STW.
7.4.2
Tuen Mun North SPS, with a design pumping
capacity of 0.342m3/s, was originally planned to collect sewage from
the local villages in the northern Tuen Mun for
conveyance to the downstream TM54
SPS under PWP No. 4374DS - Upgrading of Tuen Mun
Sewerage, Phase 1. The implementation
had been deleted from further development due to public objection on the
location of the Tuen Mun North SPS.
Details of Sewage Pumping Stations
7.4.3
Details of the SPSs in the Tuen Mun sewage catchment were obtained from
DSD, as tabulated in Table 7.1 below:
Table 7.1 Information of Sewage Pumping Stations in Tuen Mun Catchment
|
SPS
|
Tuen Mun Area 54 SPS
|
WIS SPS
|
Siu Hong SPS
|
Pak Kok SPS (Phase I)
|
Pak Kok SPS (Phase II)
|
|
No. of Duty Pump
|
3
|
2
|
3
|
2
|
1
|
|
No. of Standby Pump
|
1
|
1
|
1
|
1
|
1
|
|
Pump Capacity (L/s)
|
196
|
760
|
280
|
1,530
|
1,530
|
|
Design Capacity (m³/s)
|
0.589
|
1.52
|
0.84
|
3.06
|
1.53
|
|
Inlet Pipe Invert (mPD)
|
2.76
|
-5.1
|
0.65
|
-3.1
|
-3.1
|
|
Wet Well Invert (mPD)
|
-1.32
|
-10.4
|
-0.02
|
-3.1
|
-3.1
|
|
Approximate Wet Well Size
|
|
Area (m2)
|
2 x 55.2 = 110.4
|
144
|
49.5
|
19
|
8.6
|
|
Height (m)
|
8.7
|
16.4
|
1.6
|
3.6
|
3.6
|
|
Cut-In Level (mPD)
|
Pump 1
|
0.74
|
-8.03
|
0.5
|
-1.9
|
-1.5
|
|
Pump 2
|
0.89
|
-8.03
|
0.7
|
-1.1
|
N/A
|
|
Pump 3
|
1.04
|
N/A
|
0.9
|
N/A
|
N/A
|
|
Cut-Out Level (mPD)
|
Pump 1
|
0.48
|
-9.0
|
0.2
|
-2.3
|
-2.1
|
|
Pump 2
|
0.63
|
-9.0
|
0.4
|
-1.5
|
N/A
|
|
Pump 3
|
0.78
|
N/A
|
0.6
|
N/A
|
N/A
|
|
Note: The information was extracted from the Final
Technical Report No. 8 – Preliminary Sewerage Impact Assessment Report
prepared under Agreement No. CE 60/2013(CE) – Engineering Study for Site
Formation and Infrastructural Works at Hong Po Road.
|
|
|
Objectives and Procedures
7.5.1
The objectives and procedures of the sewerage and sewage treatment implications impact
assessment are summarised as follows:
·
Identify the scope of the
development;
·
Determine the sewage generation
of the development;
·
Identify the existing and
planned sewerage systems within and in the vicinity of the proposed development
boundary;
·
Examine the impact arising
from new sewage generation from the proposed development;
·
Propose sewerage works;
and
·
To identify, evaluate and recommend the
necessary mitigation measures and an appropriate sewage collection, treatment
and disposal proposal.
7.5.2
The assessment has been carried out in accordance with the guidelines set out in EPD’s
Technical Paper Guidelines for Estimating Sewage Flows (GESF) for Sewerage
Infrastructure Planning Version 1.0 and DSD’s Sewerage Manual.
7.5.3
The existing ground level of the SHR Site,
SHR Site Extension and HPR Site ranges from approximately +5.3 mPD to
+14.8 mPD, and
+9 mPD to
+16 mPD and
+14 mPD to
+40 mPD
respectively. The areas of the Sites
currently comprises of slopes, cottage, open storage, workshop, low-rise
village houses, factories, car parks, warehouses and temporary structures.
7.5.4
The proposed site formation level of SHR
Site, SHR Site Extension and HPR Site ranges from +6.0 mPD to +12.0 mPD, from +9.8 mPD to +12.2mPD and
from +8.0 mPD to
+21.0 mPD
respectively.
7.5.5
The location plan showing the proposed formation level of SHR Site,
SHR Site Extension and HPR Site is shown in Figure
7.2.
7.6.1
The preliminary development parameters for
SHR Site, SHR Site Extension and HPR Site are shown in Table 7.2 as
below:
Table 7.2 Proposed Development Parameters at SHR Site, SHR Site
Extension and HPR Site
|
Site
|
Zoning on the Current OZP
|
Proposed Land Use
|
No. of Flats/ Domestic Population
|
Non-Domestic GFA (m2)
|
Target Population
|
|
|
|
|
|
|
|
|
SHR Site
|
R(E) and GB on the approved Lam Tei
and Yick Yuen OZP No. S/TM-LTYY/10
&
R(E)1, GB, V and Road on
the approved Tuen Mun OZP No. S/TM/35
|
Public Housing (PH)
|
9,400/ 26,300
|
Retail
|
10,620
|
2031
|
|
Neighbourhood Elderly Centre
|
1,333.2
|
|
60-p Special Child Care Centre (SCCC)
|
902
|
|
100-p Child Care Centre (CCC)
|
1,166
|
|
OPRS Office Base
|
363
|
|
Two kindergartens
|
1,000
|
|
Two 36-classroom primary schools
|
14,000
|
|
Others*
|
21,942.8
|
|
SHR Site Extension
|
Public Housing (PH)
|
1,700/ 4,700
|
Retail
|
1,000
|
2030
|
|
One 30-classroom secondary school
|
21,000
|
|
Two 36 -classroom primary schools
|
|
Others*
|
6,298
|
|
HPR Site
|
Public Housing (PH)
|
10,500/ 30,000
|
Retail
|
8,000
|
2033
|
|
150-p Residential Care Home for the Elderly (RCHE) +
30-p Day Care Unit
|
4,406.6
|
|
Integrated Children and Youth Services Centre
(ICYSC)
|
1,388.2
|
|
Neighbourhood Elderly Centre (NEC)
|
1,333.2
|
|
Two kindergartens
|
1,520
|
|
Others*
|
21,160.5
|
|
*Allowed for provision of additional retail
facilities or welfare facilities (To be reviewed in the detailed design
stage)
|
|
|
Retail and Others
7.6.2
According to the results of the Commercial
and Industrial Floor Space Utilization Survey (CIFSUS) conducted by Planning Department,
the number of workers per 100m2 for “Retail Trade Group” is
3.5. In this connection, the total
number of employees at SHR Site is 1,140, SHR
Site Extension is 255 and HPR Site is 1,021.
Welfare Facilities
7.6.3
According to the results of the CIFSUS, the
number of workers per 100m2 for “Community, Social, and Personal
Services” is 3.3. The total number of
employees at SHR Site is 124, SHR
Site Extension is 0 and HPR Site is
235.
School
7.6.4
Kindergarten -
There are 2 nos. of 6-classrooms kindergartens and 2 nos. of 9-classrooms kindergartens at SHR Site and HPR Site
respectively. With a maximum of 30
students in each class, the total number of students at the kindergartens is
assumed to be 900. Based on Education
Bureau’s (EDB) 2017/2018 statistics, the ratio of students to teaching staff is
8.6 to 1. In this connection, the total
number of teaching staff is assumed to be 105.
7.6.5
Primary
School - There are 2 nos. of 36-classroom primary schools located at
each SHR Site and SHR Site Extension.
Taking reference to EDB’s 2017/18 statistics, 27 students are assumed in
each class and the ratio of students to teaching staff is assumed to 13.8 to 1. A total of 3,888 students and 282 teaching
staff is anticipated from the 144 classes.
7.6.6
Secondary
School - There is a 30-classroom secondary school located at SHR
Site Extension. Taking reference to
EDB’s 2017/18 statistics, 28 students are assumed in each class and the ratio
of students to teaching staff is assumed to 11.6 to 1. A total of 840 students and 73 teaching staff
is anticipated.
7.6.7
The population, employees and students
generated from SHR Site, SHR Site Extension and HPR Site are summarized in Table
7.3
below:
Table 7.3 Population,
Employees and Students Generated from SHR Site, SHR Site Extension and HPR Site
|
Site
|
Target Population Intake
|
Design population
|
No. of Employee
|
No. of Student
|
|
Retail & others
|
Welfare facilities
|
Teaching Staff
|
|
SHR Site
|
2031
|
26,300
|
1,140
|
124
|
183
(42+141)
|
2,304
(360+1944)
|
|
SHR Site Extension
|
2030
|
4,700
|
255
|
0
|
214
(141+73)
|
2,784
(1944+840)
|
|
HPR Site
|
2033
|
30,000
|
1,021
|
235
|
63
|
540
|
7.6.8
The referenced CIFSUS for “Retail
Trade Group” and “Community,
Social, and Personal Services” is enclosed in Appendix 7.1.
Tuen Mun Area 54 (TM54)
7.7.1
With reference to the Sewage Impact
Assessment prepared for Section 16 Application in April 2017, the latest
development parameters in TM54 sites are shown in Table 7.4.
Table 7.4 Development Parameters at TM54
|
Site Name
|
Design Population
|
No. of Employee
|
No. of Student
|
Tentative Year
for Completion
|
|
Site 1 &
1A
|
12,000
|
141
|
180
|
2021/22
|
|
Site 2
|
13,000
|
234
|
180
|
2018 (completed)
|
|
Site 3/4
(East)
|
15,000
|
217
|
210
|
2021/22
|
|
Site 4A
(South)
|
4,200
|
19
|
180
|
2027
|
|
Site 4A
(East)
|
-
|
176
|
2,400
|
2026/27
|
|
Site 4A
(West)
|
-
|
310
|
-
|
2022/23
|
|
Site 3/4
(West)
|
14,300
|
370
|
240
|
2024/25
|
|
Site 5
|
3,100
|
43
|
-
|
2027
|
Village Sewerage of Tsz Tin Tsuen, Po Tong
Ha, Kei Lun Wai and Siu Hang Tsuen
7.7.2
Tsz Tin Tsuen, Po Tong Ha, Siu Hang Tsuen
and Kei Lun Wai are planned with sewerage provision
for discharge to TM54 SPS. The proposed
sewerage works are tentatively scheduled to commence in Q1 2021 for completion
in Q4 2024.
7.8.1
The unit flow factors are adopted in
accordance with Environmental Protection Department’s “Guidelines for
Estimating Sewage Flows for Sewage Infrastructure Planning” (GESF). The adopted unit flow factors are summarized in Table 7.5 as follows:
Table 7.5 Recommended Unit Flow Factor
|
Development Type
|
Unit
|
Recommended Unit Flow Factor (l/d)
|
|
Existing
|
Planning for Future
|
|
Residential
|
|
Public Rental
|
Person
|
190
|
190
|
|
Employment
|
|
Job Types J4 (Wholesale
and Retail)
|
Employee
|
280
|
280
|
|
Job Types J11
(Community, Social & Personal Services)
|
Employee
|
280
|
280
|
|
School
Place
|
|
Primary, Secondary &
Tertiary
|
Student
|
40
|
40
|
7.9
Peaking Factors
7.9.1
Peaking factors cater for
seasonal/diurnal fluctuation and normal amount of infiltration and inflow. The peaking factors
shall be adopted in accordance with EPD’s GESF as shown in Table 7.6.
Table 7.6 Peaking Factors for Various Population Ranges
|
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(
|
Max(
|
|
(b) Sewage Treatment Works, Preliminary Treatment
Works and Pumping Stations
|
|
<10,000
|
4
|
3
|
|
10,000 – 25,000
|
3.5
|
2.5
|
|
25,000 – 50,000
|
3
|
2
|
|
>50,000
|
Max(
|
Max(
|
Note:
Referenced from EPD GESF Table T-5;
N = Contributing population in thousands.
|
7.10.1
The proposed development
area (PDA) is approximately 27 hectares, with a total population intake about
61,000. Welfare and educational uses are
also planned for the proposed development. This sewerage impact assessment is
based on the development parameters shown in Table 7.2.
7.10.2
The estimated sewage flows
generated by SHR Site, SHR Site Extension and HPR Site and the target
population intake are summarised in Table 7.7.
Table 7.7 Average Dry Weather Flow (ADWF)
|
Site Name
|
Population
|
Unit Flow Factor
(l/d)
|
Average DWF (m3/s)
|
Target Population Intake
|
|
SHR Site
|
26,300 residents
|
190
|
0.05784
|
2031
|
|
1,447 employees
|
280
|
0.00469
|
|
2,304 students
|
40
|
0.00107
|
|
SHR Site Extension
|
4,700 residents
|
190
|
0.01034
|
2030
|
|
469 employees
|
280
|
0.00152
|
|
2,784 students
|
40
|
0.00129
|
|
HPR Site
|
30,000 residents
|
190
|
0.06597
|
2033
|
|
1,319 employees
|
280
|
0.00427
|
|
540 students
|
40
|
0.00025
|
|
Total ADWF:
|
0.14724
|
|
7.10.3
As shown in the Table
7.7, the target population intake will be implemented in 3 phases which
is tentatively scheduled for 2030, 2031 and 2033 respectively, subject to
review at the detailed design stage. The
year-by-year sewage flow build-up on the estimated sewage flows generated by
each phase of the development is shown in Table 7.8. Detailed calculations are enclosed in Appendix
7.2.
Table 7.8 Year-by-year Sewage Flow Build-up for the Proposed
Development
|
Year
|
ADWF (m3/s)
|
|
2030
|
0.01315
|
|
2031
|
0.07677
|
|
2032
|
0.07677
|
|
2033
|
0.14724
|
7.11.1
The sewage generated from
the proposed developments will convey to the proposed TM 54 SPS for discharge
to the WIS at Ming Kum Road and subsequently to the Pillar Point STW. New
sewers are proposed to connect the proposed SHR SPS. A twin 500 diameter rising
mains are proposed to connect the SHR SPS to TM 54 SPS. The proposed local
sewerage network is shown in Figure 7.3. Upon checking of the hydraulic performance as
shown in Appendix 7.2, the proposed local sewerage network has adequate
handling capacity to convey the sewage flow from the SHR Site, SHR Site
Extension and HPR Site to the proposed SHR SPS. The sewage flow would then be conveyed via the
TM54 SPS to WIS.
7.11.2
The simulation results are
presented in Table 7.9 and Appendix 7.3.
Table 7.9 Flow Build-up of SHR SPS and TM54 SPS
|
Site Name
|
ADWF
(m3/s)
|
Contributing Population
|
Peaking Factor for SPS
|
Peak Flow for SPS
(m3/s)
|
|
SHR SPS
|
|
SHR Site
|
0.0636
|
20,349
|
|
|
|
SHR Site Extension
|
0.01314
|
4,206
|
|
|
|
HPR Site
|
0.07050
|
22,559
|
|
|
|
Subtotal
|
0.147
|
47,115
|
3.04
|
0.45
|
|
Subtotal (with 15% contingency)
|
0.169
|
54,182
|
3.01
|
0.51
|
|
Gravity to WIS
|
|
Site 1 & 1A
|
0.027
|
8,617
|
|
|
|
Site 3/4 (West)
|
0.046
|
14,719
|
|
|
|
Site 5
|
0.0069
|
2,226
|
|
|
|
TM54 SPS
|
|
Site 2
|
0.029
|
9,417
|
|
|
|
Site 3/4 (East)
|
0.034
|
10,812
|
|
|
|
Site 4A (South)
|
0.009
|
3,002
|
|
|
|
Site 4A (East)
|
0.002
|
538
|
|
|
|
Site 4A (West)
|
0.001
|
321
|
|
|
|
Village Sewerage
|
0.029
|
9,174
|
|
|
|
Subtotal
|
0.104
|
33,265
|
3.00
|
0.31
|
|
Total
|
0.273
|
87,446
|
2.92
|
0.80
|
7.11.3
The design capacity of the
proposed SHR SPS is proposed to be 0.52 m3/s with 2 duty and 1
standby pump system. The SHR SPS is
proposed to be constructed with the site formation works of SHR Site Extension and
would come into operation in 2030.
7.11.4
The design capacity of the
pumping station of the WIS, TM54 and SHR Site are shown in Table 7.10.
Table 7.10 Hydraulic Performance of SPSs
|
Sewage Pumping Station
|
Maximum Sewage Flow SPS (m3/s)
|
Design Capacity (m3/s)
|
Upgraded Design Capacity
(m3/s)/(m3/day)
|
|
SHR
SPS
|
0.51
|
0.52
|
0.52/44,928
|
|
TM
Area 54 SPS
|
0.80
|
0.59
|
0.82/70,848
|
|
WIS
SPS
|
1.24
|
1.52
|
-
|
7.11.5
As shown in Table
7.10, the design capacity of TM54 SPS would need to be further upgraded.
It is recommended to upgrade TM54 SPS
from a design capacity of 0.59m3/s to approximately 0.82m3/s.
7.11.6
As discussed in Section 7.3.5,
provision of village sewerage adjacent to TM54 SPS is planned for implementation
in Q1 2021. It is recommended to review the implementation programme
of the sewerage provision project in order to confirm the time frame/ required
capacity for upgrading the TM54 SPS.
7.11.7
With the proposed
upgrading of the TM54 SPS, the twin 500 diameter rising mains downstream of
TM54 SPS would operate with a peak velocity of 1.83m/s which is considered
adequate for sewage rising mains. Therefore,
only minor modification of internal pipework within the SPS is anticipated. The current Environmental Permit (EP) of TM54
SPS comprises the construction and operation of a SPS with a capacity of
90,000m3/day; hence, upgrading of the TM54 SPS would not require a
variation of EP.
7.11.8
The upgrading works is
proposed to be carried out by DSD. The
detailed construction works would be determined in the detailed design stage.
7.11.9
Sewage generated from SHR
Site, SHR Site Extension and HPR Site and the nearby interfacing Tuen Mun Area 54 development is ultimately discharged to
the Pillar Point STW for treatment and disposal. The treatment capacity of Pillar Point STW is
241,000 m3/day (ADWF).
7.11.10
Based on the results from
the hydraulic model, Pillar Point STW would have adequate capacity to cater for
the sewage flow generated from the PDA.
7.12.1
In order to avoid the
occurrence for emergency discharges, the design SPS shall comprise additional
provisions, including:
·
Twin
rising mains in case of one of the duty mains be taken out of operation, the
remaining one would still be able to deliver flow;
·
Standby pumps and screens in case of
unexpected breakdown of maintenance of the pumps and screens such that the
standby pumps and screens could take over and allow continuous operation of the
SPS;
·
Dual electricity supply from
different power sub-stations or backup power supply facilities such as diesel
generator in case of power failure to sustain the function of pumping
facilities;
·
A storage tank with 2-hour ADWF capacity (about 1,200m3) to hold temporary discharge for a duration
required to restore normal operation of the SPS to cater for breakdown and
maintenance of the SPS. The proposed SHR SPS is located in
urban area, maintenance team can arrive within short time to investigate the
problem and resume the SPS operation as soon as possible. Detail arrangement
will be formulated in later design stage;
·
Supervisory Control and Data Acquisition (SCADA) system and
closed-circuit television (CCTV) will be provided for active monitoring in
order to transmit signals showing irregularity or any operational problem of
the SPS to the nearby STW or other manned SPS such that immediate actions can
be taken in case of emergency; and
·
A hand-cleaned bar screen to cover the lower half of the opening of any
overflow bypass to prevent the discharge of floating solids to the receiving
water bodies. The clear spacing of the bar screen should normally be 25
mm.
7.12.2
In addition, regular
maintenance and plant inspection will be conducted throughout the operation of
the SPS to prevent equipment failure. Regular inspection, at least once per
week, should cover the essential equipment in the pumping station. With the
above measures implemented, abnormality of the equipment should be identified
for remedial action to be taken before failure.
7.12.3
In addition, a contingency
plan to deal with the unlikely event of emergency discharge during the
operation of the SPS should be developed in the detailed design stage. The contingency plan should be prepared by referring to (i) “A Guide on Reporting Sewage Bypass Incidents in Sewage
Pumping Stations and Sewers” by the EPD of March 2015 and (ii)
"Contingency Plan for Incidents Possibly Encountered in Sewage Treatment
Facilities having a Potential of Generating an Environmental Nuisance" by
the DSD. The contingency plan should include the following items:
·
Locations of waterbodies
or WSRs in the vicinity of the emergency discharge;
·
A list of relevant
government departments (including name, address, email address phone and fax
number of the key persons) to be informed and their respective follow up action
in the event of emergency discharge, including key contact person and telephone
numbers;
·
A framework of emergency
response and reporting procedures required in the event of emergency
discharges; and
·
Procedures listing the
most effective means in rectifying the breakdown of the SPS in order to
minimize the discharge duration.
7.13.1
The latest development
parameters of the proposed development at SHR Site, HPR Site and SHR Site
Extension, along with the latest information on the existing and planned
sewerage network in Tuen Mun were obtained and
reviewed.
7.13.2
The proposed SHR SPS would
collect sewage from SHR Site, SHR Site Extension and HPR Site for conveyance to
the downstream sewerage system.
7.13.3
Only minor impact to the
downstream sewerage network is anticipated. In particular, the sewers at the upstream
of the TM54 SPS (Section M15.1, M16.1, M17.1 & M18.1) are proposed to be
upgraded from DN750 to DN900 and the capacity of the TM54 SPS is proposed to be
upgraded from 0.59m3/s to 0.82m3/s in order to handle the
sewage generated from the northern Tuen Mun catchment
including the planned development in Tuen Mun Area 54
and the proposed development under this project.
7.13.4
The Pillar Point STW would
have adequate treatment capacity to cater for the sewage flow generated from the
planned development at TM Area 54 and the proposed development under this
project.
END OF TEXT