13.
CONCLUSION
13.1.2
According to the Brief, the project programme is
shown as below:
|
|
Treatment Capacity
(m3/day)
|
Tentative Year of
Commissioning
|
|
|
Increased by
|
Total
|
|
Existing
|
-
|
1,660
|
-
|
|
Phase 1
|
3,340
|
5,000
|
2021
|
|
Phase 2
|
5,000
|
10,000
|
End 2030
|
13.2.2
The works for this Project in Sha Tau Kok mainly
comprises of the following items :
a)
Increase the
treatment capacity of Sha Tau Kok Sewage Treatment Works (STKSTW) to 5,000 m3/day
at Average Dry Weather Flow (ADWF) by 2021, with suitable
allowance to cater for a further increase of treatment capacity to 10,000 m3/day
at ADWF after 2030 in Phase 2;
b)
Construct a temporary sewage treatment plant (TSTP);
c)
Demolish the
existing Sha Tau Kok Sewage Pumping Station (STKSPS) and decommission the
rising main between STKSPS and STKSTW;
d)
Construct a new
gravity sewer; and
e)
Decommission the existing submarine outfall and
construct a new one.
a)
Schedule 2, Part
I, Item F.2 (a) and (b)(i) - Sewage Treatment Works with an installed capacity
of more than 5,000 m3 per day; and a boundary of which is less than
200m from the nearest boundary of the an existing residential area; and
b)
Schedule 2, Part
I, Item F.6 - a submarine outfall.
13.3
Purpose and Approach of the EIA Study
a)
The overall
acceptability of any adverse environmental consequences that are likely to
arise as a result of the proposed Project;
b)
The conditions
and requirements for the detailed design, construction and operation of the
proposed Project to mitigate against adverse environmental consequences, as
practicable; and
c)
The acceptability
of residual impacts after implementation of the proposed mitigation measures.
13.3.2
The specific objectives of the EIA Study are
described in Clause 2 of the EIA Study Brief, and the detailed requirements of
the EIA Study are set out in Clause 3 of the EIA Study Brief. As specified in the EIA Study Brief, the EIA
Study has addressed the key environmental issues associated with the
construction and operation of the Project.
Existing Conditions
13.4.3
The existing submarine outfall is discharging
near-shore of Starling Inlet. The discharge point is close to the nearby
fish culture zone. A new submarine outfall and hence a new discharge point
would be required to facilitate the increase in sewage flow and to improve the
dilution of effluent by water current.
Purpose of the Project
Environmental Benefits of the Project
a)
Improve treatment
to produce effluent with better quality;
b)
Provide more
treatment capacity within the existing plant site;
c)
Cover the
treatment facilities and provide odour treatment to improve air quality;
d)
Incorporate
environmental enhancements in the new treatment facilities, including renewable
energy, energy-efficient electrical and mechanical equipment, greening, water
saving measures, etc.;
e)
Locate the
discharge point of the new submarine outfall away from sensitive receivers,
including the fish culture zones and the identified species of conservation
importance; and
f)
Demolish STKSPS
to make the land available for other beneficial purposes.
13.5.1
Table 13.1 presents a summary of the project details. The footprint of the
proposed expansion of STKSTW will be approximately 4,950 m2, with a 524m of
gravity collection sewerage system along Shun Hing Street. A maximum total
marine dredging volume of 3,040m3 of marine sediments will be generated from
the construction of diffuser for the submarine outfall.
Table 13.1 Summary of Project Description
|
Details
|
Preliminary Design Information
|
|
Submarine Utilities
|
|
|
Excavated
Sediment volume (in situ volume)
|
|
|
·
Diffuser
|
3,040 m3
|
|
Length of
Submarine Utilities (m)
|
|
|
·
Outfall
|
~ 1.7 km
|
|
Expanded Sha Tau Kok Sewage Treatment Works
|
|
|
Footprint
|
4,950 m2
|
|
Dimension of
above-ground structure
|
73m (L) x 25m (W)
|
|
Building
height
|
Ranged 10m
–19m
|
|
Site Coverage
|
35%
|
|
Gross Floor
Area
|
5,700m2
|
|
Temporary Sewage Treatment Plant
|
|
|
Footprint
|
774 m2
|
|
Dimension of above-ground
structure
|
47m (L) x 19m (W)
|
|
Building
height
|
10m
|
|
Gravity Sewer
|
|
|
Excavation
volume
|
4,620 m3
|
|
Length of the
gravity sewer
|
524 m
|
|
|
|
Table 13.2 Key Dates of Implementation Programme
|
Item
|
Tentative Date
|
|
Approval
of Application for Permission under
Section 16 of the Town Planning Ordinance
|
Nov 2016
|
|
Tender Gazette
|
Jan 2017
|
|
Commencement of Construction
|
May 2017
|
|
Completion of Construction
|
Dec 2022
|
a)
Alternative
treatment level: Secondary treatment level has been considered for STKSTW,
which is capable of removing biodegradable organic matter, suspended solids and
total nitrogen for compliance with the Water Quality Objectives of Mirs Bay
Water Control Zone. The treatment method can fulfil the Project requirements
without causing adverse water quality and ecological impact.
b)
Alternative
treatment process: Three secondary treatment processes have been investigated,
which are Membrane Bioreactor (MBR), Moving Bed Bioreactor with Dissolved Air
Floatation (MBBR+DAF) and Sequencing Batch Reactor (SBR). Compared with MBBR
and SBR, MBR can provide the best effluent quality within the same footprint.
MBR is thus adopted as the preferred treatment process for the expansion of
STKSTW
c)
Alternative new
locations for new treatment facilities: Three expansion options have been
investigated, which is utilizing new site for construction of TSTP, expansion
within the existing site and utilizing the existing police operation base for
expansion. Compared to utilizing extra land, expansion within the existing
footprint create less environmental impacts since the footprint is far from
residential area.
d)
Alternative
submarine outfall alignment: Two discharge locations have been considered, one
is discharging in the vicinity of the existing outfall discharge location and
one is discharging further away in the water near Ah Kung Au. Preliminary
modelling results showed that compliance with Water Quality Objectives of Mirs
Bay Water Control Zone maybe difficult if discharging in the vicinity of the
existing outfall discharge location and hence discharging in the water near Ah
Kung Au is preferred.
e)
Phased
installation for different flow projections: Single phase and phased
installations for E&M works have been considered. Phased installation is
preferred so as to avoid the amount of idled equipment which will increase the
energy consumption for maintenance.
f)
Alternative
designs to avoid or minimize emergency discharge: Different precautionary
measures have been investigated, such as dual power supply, backup generator,
standby equipment, provision of onsite storage and tanker away. Tanker away is not preferred because large
number of tankers required will cause additional air quality and noise impact
to the nearby residential area. It is proposed to provide dual power supply,
standby equipment and provision of onsite storage for minimizing the risk of emergency
discharge.
g)
Other
considerations: Considerations have also been given to the demolition of Sha
Tau Kok Sewage Pumping Station and new sewer alignment. It is considered to
demolish the STKSPS and replace it with a gravity collection system along Shun
Hing Street.
a)
Limit
the footprint to 5,000m2 for the construction works to the existing
STKSTW site. This is far from residential area and comparatively less
environmental impacts will be created.
b)
Provide the best effluent quality within a small footprint.
c)
Odour,
noise and visual impacts to surrounding sensitive receivers can be minimized.
d)
Fewer
sensitive receivers are immediately affected (Sha Tau Kok Chuen, Sha Tau Kok
Recreation Ground and Police Operation Base) during construction and operation in
comparison to the other option.
e)
Safeguard
water quality at Starling Inlet.
f)
Can
achieve the Water Quality Objectives of Mirs Bay Water Control Zone
g)
Proposed
outfall located further away from Sha Tau Kok Fish Culture Zone
h)
Reduce
extent of land required for construction and hence reduce the environmental
impacts to nearby sensitive receivers
i)
Reduce
the amount of idle equipment which increase energy efficiency
j)
Reduce
use of chemicals required for the maintenance of the idle equipment
k)
No
significant impact to the marine ecology in comparison to the dredging method.
Approximately 3,040m3 sediment will be removed.
-
LR6.10
- Trees surrounding Sha Tau Kok Sewage Treatment Works
-
LCA4
- Boundary Crossing Facilities Landscape
-
LCA5
- Sha Tau Kok Rural Township Landscape
-
VSR
R1 - Residents in Block 42 – 45 of Sha Tau Kok Chuen
-
VSR
R2 - Residents in Ha Tam Shui Hang
-
VSR
R3 - Residents in Muk Min Tau
-
VSR
R4 - Residents in Block 13-15 of Sha Tau Kok Chuen
-
VSR
R5 - Residents at 3-17 Shun Lung Street
-
VSR
R6 - Residents of Public Housing Development at Shun Hing Street
-
VSR
O1 - Workers/Officers in Sha Tau Kok Fire Station
-
VSR
O2 - Police Operation Base
-
VSR
O3 - Workers of Sha Tau Kok Fish Culture Zone
-
VSR
T1 - Motorists on Sha Tau Kok Road
-
VSR
T2 - Marine users on Starling Inlet
-
VSR
RE1 - Recreational Users of Sha Tau Kok Chuen Area
-
VSR
RE2 - Recreational Users of Sha Tau Kok Promenade Sitting-out Area (1)
-
VSR
RE3 - Recreational Users of Land Use Zoning REC(1)
-
VSR
RE4 - Recreational Users at Yim Liu Ha
-
VSR
RE5 - Recreational Users of Sha Tau Kok Promenade Sitting-out Area (2)
13.15.6
During the course of developing the proposed
project and assessing the landscape and visual aspects, a series of mitigation
measures are carefully considered in the project design for impact avoidance,
impact minimisation and landscape and visual enhancement as far as practical. Recommended
mitigation measures include preservation of existing trees, proper control of
site construction activities, suitable design of the expanded STKSTW, amenity/compensatory
planting and amenity enhancement.
13.15.9
At Year 10 of operation, LR6.10 will receive
slight beneficial impact with full establishment of mitigation measures during
the operation period. The reason for the slight beneficial impact experienced
by the LR6.10 is that there will be a net gain of tree planting area (increased
to 0.42ha from original 0.31ha) and overall planting area (increased to 0.45ha
from original 0.31ha). VSR T2 would experience slight adverse mitigated impacts
during the operation phase, which is considered within acceptable range due to
the low sensitivity in nature of the travelling type VSR, the glimpse duration
of view and its panoramic quality of views over the Starling Inset seascape.
All others receivers (LCA4, LCA5, R1, R2, R3, R4, R5, R6, T1, O1, O2, O3, RE1,
RE2, RE3, RE4, RE5) will experience insubstantial impact with full
establishment of mitigation measures during the operation period.
13.15.11
LR6.10 - Trees surrounding Sha Tau Kok Sewage
Treatment Works
13.18
Overall Conclusion
13.18.2
Recommendations for an environmental monitoring
and audit programme have been prepared to ensure the effectiveness of the
recommended mitigation measures.