13. CONCLUSIONS AND RECOMMENDATIONS
|
Approximate Dimension (m) |
Site Area |
||
|
Length |
Width |
Height* |
|
P1A |
|
202.5m2 |
||
Pumping Station |
11.85 |
4.0 |
300mm |
14.22m2 |
Deodourizer |
3 |
1 |
3 |
9m2 |
Standby Generator |
5 |
4.5 |
3.5 |
70m2 |
Control Kiosk |
2.6 |
1.5 |
1.5 |
5.85m2 |
P1B |
|
241 m2 |
||
Pumping Station |
11.85 |
4.0 |
300mm |
14.22m2 |
Deodourizer |
3 |
1 |
3 |
9m2 |
Standby Generator |
5 |
4.5 |
3.5 |
78.75m2 |
Control Kiosk |
2.6 |
1.5 |
1.5 |
5.85m2 |
P2 |
|
310 m2 |
||
Pumping Station |
11.85 |
4.0 |
300mm |
14.22m2 |
Deodourizer |
3.5 |
1.5 |
3.2 |
9m2 |
Standby Generator |
5 |
6 |
3.5 |
105m2 |
Control Kiosk |
2.6 |
1.5 |
1.5 |
5.85m2 |
STW |
Refer to Figure 10.13 for layout |
Refer to Figure 10.13 for layout |
7.0m max. |
1529 m2 |
Note: * Height above ground level
Table 13.1 Summary of Key Environmental Outcomes/benefits
Issue |
Mitigation Measures and Environmental Outcomes/Benefits |
The Project
|
Provision of a new sewage collection, treatment and disposal facilities for Sok Kwu Wan area in order to:
· Eliminate the direct discharges of untreated or partially treated sewagegenerated from approximately 1300 residents, 6000 day visitors and restaurants in Sok Kwu Wan area into coastal area of Picnic Bay in 2016 (which are equivalent to the ultimate population figures) as well as from Lo So Shing and Mo Tat Wan which would have total residents of approximately 532 in 2016. · Improve the water quality of Picnic Bay. · Improve the local environment in the residential areas by eliminating unhealthy, malodorous and potentially visually unpleasant surface discharges.
|
Option Selection & Design |
The locations and design of the proposed sewer alignment, pumping stations, STW and submarine outfall are considered environmental friendly due to the following reasons:
· Avoid or reduce impacts on sites of archaeological interest and cultural heritage importance (Lo So Shing Archaeological Site). · Avoid reclaiming land for STW construction. · Reduce the risk of untreated sewage leakage by selecting the route with shorter pipeline on land. · Minimizethe encroachment into private lot and the LCSD playground. · Minimize the loss/disturbance of vegetated areas. · Avoid direct impact on coral habitats with the use of HDD. · Minimize potential water quality impacts on nearby sensitive receivers by extending the outfall length, eliminating the need of reclamation, and using of no-dig method for inshore section of the outfall pipeline. · Improve water quality of Picnic Bay by eliminating the discharge of untreated or partially treated sewage and providing a full secondary treatment with nitrogen removal and UV disinfection unit. · Minimize the extent of construction dust and noise impacts (i.e. the selected route would avoid affecting the receivers in Lo So Shing)
|
Air Quality –Construction Phase |
2m high solid fence around construction site of Pumping Station P2 and dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation are proposed to protect the nearby ASRs.
All ASRs would be protected to comply with AQQ and EIAO-TM standards.
|
Air Quality –Operation Phase |
All pumping stations, sequence batching reactor (SBR) feed pump station and sludge dewatering room would be enclosed and installed with deodorisation facilities.
All ASRs would comply with of EIAO-TM odour standard.
|
Noise – Construction phase
|
Use of quieter plants, limiting number of some powered mechanical equipment, use of noise screening structures and manual working method are proposed to protect the NSRs located near the pumping stations and along the sewer alignment.
All NSRs comply with EIAO-TM noise standards, except short-term residual impact during sewer construction.
|
Noise – Operation phase |
Installation of a silencer with at least 8 dB(A) noise reduction at Pumping Station P1a is recommended.
All NSRs would be protected to meet both daytime and nighttime noise criteria.
|
Water Quality – Construction Phase |
Use of HDD for the inshore section outfall pipeline installation, reduction of dredging rate and use of 2-layer silt curtains are recommended to protect the FCZ at Picnic Bay and secondary contact recreation subzone at Mo Tat Wan.
The FCZ and secondary contact recreation subzone would be protected to be within the relevant WQO.
|
Water Quality – Operation Phase (Normal Operation)
|
Provision of full secondary treatment with nitrogen removal and UV disinfection and disposal of treated sewage at a long submarine outfall near the mouth of Picnic Bay.
The FCZ and secondary contact recreation subzone would comply with WQO, except WQO limit for TIN due to the high background level which has already exceed the limit. The predicted TIN levels would fall within the background variations of TIN levels at Picnic Bay.
|
Water Quality – Operation Phase (Emergency Discharge) |
Mitigation measures such as provision of standby pump and standby generator, 24-hour temporary storage and contingency measures are recommended to minimize the occurrence of emergency discharge and potential water quality impact if an overflow does occur, in order to protect the FCZ at Picnic Bay.
With the implementation of the recommended mitigation measures and contingencies, the occurrence of emergency discharge and the residual impacts in the unlikely event that an overflow does occur would be minimised.
|
Ecology |
Use of HDD for the inshore section of outfall pipeline would avoid the loss of coral habitats and reduce the temporary seabed loss due to dredging.
Fencing and labelling of uncommon tree species is proposed to avoid direct or indirect disturbance during construction.
No significant and unacceptable residual impact would be expected.
|
Fisheries |
With the implementation of the mitigation measures recommended for the water quality impact, no unacceptable residual impact on fisheries would be expected.
|
Landscape and Visual Impact |
Appropriate construction practice, design and surface treatment of the built elements and appropriate soft landscape treatment within available areas of the Project are recommended to mitigate the potential landscape and visual impacts.
Landscape and visual impacts would be acceptable with the recommended mitigation measures.
|