Ÿ Technical Memorandum on Noise from Places other than Domestic Premises, Public Places or Construction Sites (IND-TM):
Ÿ Technical Memorandum on Noise from Construction Work in Designated Areas (DA-TM);
Ÿ Technical Memorandum on Noise from Construction Work other than Percussive Piling (GW-TM); and
Ÿ Technical Memorandum on Noise from Percussive Piling (PP-TM).
Construction Noise
Table 4.1 : Noise Standards for Daytime Construction Activities
|
Noise Sensitive Uses |
0700 to 1900 hours on any day not being a |
|
Domestic premises, hotels and hostel |
75 |
|
Educational institutions (normal teaching periods) |
70 |
|
Educational institutions (examination periods) |
65 |
Notes:
1) The above noise standards apply to uses, which rely on opened windows for ventilation.
2) The above standards shall be viewed as the maximum permissible noise levels assessed at 1m from the external facade.
3) The above standards shall be met as far as possible. All practicable mitigation measures shall be exhausted and the residual impacts are minimized.
Operational Noise
Table 4.2 : Acceptable Noise Levels
|
Time Period |
ASR A |
ASR B |
ASR C |
|
All days during the evening (1900 to 2300 hours), and general holidays (including Sundays) during the day-time and evening (0700 to 2300 hours) |
60 |
65 |
70 |
|
All days during the night-time (2300 to 0700 hours) |
50 |
55 |
65 |
Ÿ 5 dB(A) below the appropriate ANL set out in the IND-TM (the ANL–5 dB(A) criterion), or
Ÿ The prevailing background noise level where the prevailing background noise level is 5 dB(A) below the appropriate ANL (although during the operation the NCO will be the controlling legislation).
Background Noise Measurements
Table 4.3 : Background Noise Measurement Results
|
Measurement Location |
Measured Noise Level(1), Leq(30 min) (daytime / nighttime), dB(A) |
Area Sensitivity Rating |
ANL-5 dB(A) (daytime / nighttime), dB(A) |
Recommended Operational Noise Assessment Criteria (daytime / nighttime), dB(A) |
|
Near Cheung Chau STW - |
53 / 54 |
A |
55 / 45 |
53 / 45 |
|
Near Pak She SPS - |
56 / 53 |
A |
55 / 45 |
55 / 45 |
(1) A façade correction of +3 dB(A) has been included.
Noise Sources Identification
Table 4.4 : Summary of related Works Type
|
Works Type |
Description of |
|
Works Type 1 |
Construction of Sewer (Open Cut Method) |
|
Works Type 2 |
Construction of Sewer (Trenchless Method) |
|
Works Type 3 |
Upgrading of Existing Sewer |
|
Works Type 4 |
Upgrading of Pak She Sewage Pumping Station |
|
Works Type 5 |
Upgrading of Cheung Chau Sewage Treatment Works |
|
Works Type 6 |
Rehabilitation of Existing Sewer |
|
Works Type 7 |
Temporary Concrete Mixing (within Cheung Chau STW) |
Table 4.5 : Construction Activities Schedule
|
Works Stage |
Construction Activities |
Calculated Worst-case SWL, dB(A) |
|
Works Type 1 - Construction of Sewer (Open Cut Method) |
||
|
Stage 1 |
Breaking up of road surface |
103 |
|
Stage 2 |
Excavation of soil material |
95 |
|
Stage 3 |
Steel fixing & concreting of manholes |
110 |
|
Stage 4 |
Laying of bedding material |
113 |
|
Stage 5 |
Backfilling and soil compaction |
102 |
|
Stage 6 |
Reinstatement of road surface |
113 |
|
Works Type 2 - Construction of Sewer (Trenchless Method) (Intervals between 2 manholes) |
||
|
Stage 1 |
Excavation of Pits |
122 |
|
Stage 2 |
Jacking of pipes |
118 |
|
Stage 3 |
Steel fixing and concreting of manholes |
110 |
|
Stage 4 |
Reinstatement of road surface with bricks |
No PME involved |
|
Works Type 3 - Upgrading of Existing Sewer |
||
|
Stage 1 |
Breaking up of road surface |
103 |
|
Stage 2 |
Excavation of soil material |
95 |
|
Stage 3 |
Removal of existing sewers and laying of new sewers |
94 |
|
Stage 4 |
Steel fixing & concreting of manholes |
110 |
|
Stage 5 |
Laying of bedding materials |
113 |
|
Stage 6 |
Backfilling and soil compaction |
102 |
|
Stage 7 |
Reinstatement of road surface |
110 |
|
Works Type 4 - Upgrading of Pak She Sewage Pumping Station |
||
|
Stage 1 |
Partial removal of existing structure |
122 |
|
Stage 2 |
Partial reconstruction of structures |
119 |
|
Stage 3 |
Replacement of E&M equipments |
112 |
|
Works Type 5 - Upgrading of Cheung Chau Sewage Treatment Works |
||
|
Stage 1 |
Demolish the abandoned filter beds |
123 |
|
Stage 2 |
Modification and diversion of pipework |
123 |
|
Stage 3 |
Construction and upgrading of treatment facilities |
123 |
|
Stage 4 |
Construction of the new pump house |
123 |
|
Stage 5 |
Demolish of primary sedimentation tanks & sludge digestor |
122 |
|
Stage 6 |
Construction of the new storm tanks and workshop |
123 |
|
Works Type 6 - Rehabilitation of Existing Sewers (for 20 meters) |
||
|
Stage 1 |
Rehabilitation of existing sewer |
104 |
|
Works Type 7 - Temporary Concrete Mixing |
||
|
Stage 1 |
Operation of concrete mixer |
96 |
Notes:
1) The various stages involved for each work type will not be undertaken concurrently.
2) Note that works programme is subject to variables such as weather, conflicts with utilities, etc. and is variable upon these conditions.
3) “SWL” is the calculated worst-case total sound power level due to the operation of the plant inventory for that works stage based on the unmitigated scenario.
Noise Sensitive Receivers
Table 4.6 : Representative Noise Sensitive Receivers (Construction Phase)
|
NSR |
Description of NSR |
Nature of Use |
No. of Floor |
Figure No. |
Construction Phase Works Type that will Affect the NSR |
||||||
|
1 |
2 |
3 |
4 |
5 |
6 |
7 |
|||||
|
TKST2 |
No.4 Tai Kwai San Tsuen |
Residential |
2 |
4.2 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
CSH1* |
Chung Shak Hei Home for the Aged |
Homes for the Aged |
2 |
4.3 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
CKH* |
Cheung King House |
Residential |
4 |
4.4 |
-- |
-- |
-- |
-- |
√ |
-- |
√ |
|
CSH2* |
Cheung Shun House |
Residential |
4 |
4.4 |
-- |
-- |
-- |
-- |
√ |
-- |
√ |
|
PSSL* |
No. 1A Pak She Second Lane |
Residential |
3 |
4.5 |
-- |
-- |
-- |
√ |
-- |
-- |
-- |
|
CCEP |
No.7 Cheung Chau Electric Path |
Residential |
3 |
4.6 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
ST |
Block D Seaview Terrence |
Residential |
3 |
4.8 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
SW1 |
3A Golden Lake Garden |
Residential |
3 |
4.7 |
√ |
-- |
√ |
-- |
-- |
-- |
-- |
|
THT |
No.24 Tai Hing Tai Road |
Residential |
3 |
4.7 |
√ |
-- |
√ |
-- |
-- |
-- |
-- |
|
SYT1 |
No.2A Sin Yan Tseng |
Residential |
2 |
4.8 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
SYT2 |
No.37 Sin Yan Tseng |
Residential |
2 |
4.8 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
P1 |
No. 34 Praya Street |
Residential |
3 |
4.9 |
-- |
√ |
-- |
-- |
-- |
√ |
-- |
|
TW1 |
Cheung Chau Fisheries Joint Association Public School |
Educational |
2 |
4.9 |
√ |
√ |
√ |
-- |
-- |
-- |
-- |
|
TSB1 |
No. 123 Tai San Back Street |
Residential |
3 |
4.10 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
LTT1 |
Cheung Chau Alliance Church |
Church |
2 |
4.11 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
LTT2 |
No.35 Lung Tsai Tsuen Road |
Residential |
3 |
4.11 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
P2 |
No.41A Peak Road |
Residential |
3 |
4.11 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
KYW1 |
No.31 Kwun Yam Wan Road |
Residential |
2 |
4.12 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
CCS2 |
Block G-H Fu Yuen |
Residential |
3 |
4.12 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
PR1 |
No.25 Peak Road |
Residential |
2 |
4.13 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
PR2 |
No.72 Peak Road |
Residential |
2 |
4.13 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
KYW2 |
No.46 Kwun Yam Wan Road |
Residential |
3 |
4.14 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
MF1 |
Caritas Ka Fai House |
Residential |
2 |
4.14 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
FP1 |
No.18 Fa Peng Road |
Residential |
3 |
4.15 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
|
FP2 |
Bethany Cottage and House |
Residential |
3 |
4.15 |
√ |
-- |
-- |
-- |
-- |
-- |
-- |
Notes:
NSR ID marked with * is located within the 300 m radius of the boundary of Cheung Chau STW and Pak She SPS
All representative NSRs identified are existing NSRs.
Works Type 1 - Construction of sewer (Open Cut Method).
Works Type 2 - Construction of sewer (Trenchless Method).
Works Type 3 - Upgrading of existing sewers.
Works Type 4 - Upgrading of Pak She Sewage Pumping Station.
Works Type 5 - Upgrading of Cheung Chau Sewage Treatment Works.
Works Type 6 - Rehabilitation of existing sewers.
Works Type 7 - Temporary Concrete Mixing.
Local ground mPD levels at the NSRs are shown on the respective Figure 4.2 to Figure 4.15.
Construction Noise Impact Evaluation
Ÿ Locate the NSRs which would most likely be affected by noise from construction work;
Ÿ Determine the items of Powered Mechanical Equipment (PME) for each discrete construction activity, based on available information or agreed plant inventories;
Ÿ Assumptions for on-time percentage of certain PME have been made. The Project Proponent’s design engineer confirmed that the assumption of on-time percentage and number of PME are considered to be practical in completing the works within the schedule;
Ÿ Calculate the distance attenuation and screening effects to NSRs from notional noise source. Under the Technical Memorandum on Noise from Construction work other than Percussive Piling (GW-TM), the distance attenuation will be determined by the following formula;
Ÿ Distance Attenuation in dB(A) = 20 Log D + 8 [where D is distance in metres];
Ÿ A +3 dB (A) façade correction is added to the predicted noise levels to account for the façade effect at each NSR;
Ÿ Calculate the unmitigated Predicted Noise Level (“PNL”) and correct it for façade reflection to obtain the Corrected Noise Level (“CNL”) at any NSRs;
Ÿ If necessary, re-select typical project-specific silenced equipment and other types of mitigation measure to address noise exceedance, e.g. noise barrier and calculate the mitigated noise impact; and
Ÿ Compare the mitigated CNL with the noise standards to determine acceptability and the need for further mitigation/ EM&A.
Table 4.7 : Predicted Worst-case Cumulative Construction
Noise Levels at
Representative NSRs Affected by Upgrading of Cheung Chau STW and Pak She SPS -
Unmitigated Scenario
|
NSR |
Description of NSR |
Predicted Worst-case Construction Noise Level |
|||
|
Works Type 4 |
Works Type 5 |
Works Type 7 |
Total |
||
|
CKH |
Cheung King House |
-- |
77 |
48 |
77 |
|
CSH2 |
Cheung Shun House |
-- |
76 |
47 |
76 |
|
PSSL |
No. 1A Pak She Second Lane |
86 |
-- |
-- |
86 |
Notes:
Underlined bold figure (e.g. 77) indicates an exceedance of the 75 dB(A) noise criteria.
Works Type 4 - Upgrading of Pak She Sewage Pumping Station.
Works Type 5 - Upgrading of Cheung Chau Sewage Treatment Works.
Works Type 7 - Temporary Concrete Mixing.
Table 4.8 : Predicted Worst-case Cumulative
Construction Noise Levels at
Representative NSRs Affected by sewers works- Unmitigated Scenario
|
NSR |
Description of NSR |
Predicted Worst-case Construction Noise Level |
||||
|
Works Type 1 |
Works Type 2 |
Works Type 3 |
Works Type 6 |
Total |
||
|
TKST2 |
No. 4 Tai Kwai San Tsuen |
108 |
-- |
-- |
-- |
108 |
|
CSH1* |
Chung Shak Hei Home for the Aged |
108 |
-- |
-- |
-- |
108 |
|
CCEP |
No.7 Cheung Chau Electric Path |
108 |
-- |
-- |
-- |
108 |
|
ST |
Block D Seaview Terrence |
94 |
-- |
-- |
-- |
94 |
|
SW1 |
3A Golden Lake Garden |
94 |
-- |
86 |
-- |
95 |
|
THT |
No.24 Tai Hing Tai Road |
94 |
-- |
82 |
-- |
94 |
|
SYT1 |
No.2A Sin Yan Tseng |
102 |
-- |
-- |
-- |
102 |
|
SYT2 |
No.37 Sin Yan Tseng |
108 |
-- |
-- |
-- |
108 |
|
P1 |
No. 34 Praya Street |
-- |
98 |
-- |
73 |
98 |
|
TW1 |
Cheung Chau Fisheries Joint Association Public School |
102 |
102 |
99 |
-- |
106 |
|
TSB1 |
No. 123 Tai San Back Street |
108 |
-- |
-- |
-- |
108 |
|
LTT1 |
Cheung Chau Alliance Church |
108 |
-- |
-- |
-- |
108 |
|
LTT2 |
No.35 Lung Tsai Tsuen Road |
108 |
-- |
-- |
-- |
108 |
|
P2 |
No.41A Peak Road |
108 |
-- |
-- |
-- |
108 |
|
KYW1 |
No.31 Kwun Yam Wan Road |
91 |
-- |
-- |
-- |
91 |
|
CCS2 |
Block G-H Fu Yuen |
108 |
-- |
-- |
-- |
108 |
|
PR1 |
No.25 Peak Road |
102 |
-- |
-- |
-- |
102 |
|
PR2 |
No.72 Peak Road |
96 |
-- |
-- |
-- |
96 |
|
KYW2 |
No.46 Kwun Yam Wan Road |
102 |
-- |
-- |
-- |
102 |
|
MF1 |
Caritas Ka Fai House |
102 |
-- |
-- |
-- |
102 |
|
FP1 |
No.18 Fa Peng Road |
102 |
-- |
-- |
-- |
102 |
|
FP2 |
Bethany Cottage and House |
102 |
-- |
-- |
-- |
102 |
Notes:
NSR ID marked with * is located within the 300 m radius of the boundary of the Cheung Chau STW and Pak She SPS but no line of sight to the site.
Underlined bold figure (e.g. 77) indicates an exceedance of the 75 dB(A) noise criteria.
Noise criteria for TW1 (school) is 70 dB(A) during normal hours (65 dB(A) during examination periods).
Noise criteria for LTT1 is 70 dB(A) is a place of worship where unaided voice communication is required.
Works Type 1 - Construction of sewer (Open Cut Method).
Works Type 2 - Construction of sewer (Trenchless Method).
Works Type 3 - Upgrading of existing sewers
Works Type 6 - Rehabilitation of existing sewers
Noise Mitigation Measures for Upgrading of Cheung Chau STW and Pak She SPS
Good Site Practice
Ÿ only well-maintained plant should be operated on-site and plant should be serviced regularly during the construction works;
Ÿ machines and plant that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum;
Ÿ plant known to emit noise strongly in one direction should, where possible, be orientated to direct noise away from the NSRs;
Ÿ mobile plant should be sited as far away from NSRs as possible; and
Ÿ material stockpiles and other structures should be effectively utilized, where practicable, to screen noise from on-site construction activities.
Adoption of Quiet PMEs and Site Hoardings Screening
Table 4.9 : Quiet PME and Associated Sound Power Level
|
Description of PME |
Equivalent Quiet PME |
SWL, dB(A) |
|
Generator |
BS 5228 Table C4/77 |
88 |
|
Poker, vibratory, hand-held |
BS 5228 Table C4/34 |
97 |
|
Breaker, excavator mounted (hydraulic) |
BS 5228 Table C9/12 |
113 |
|
Excavator |
BS 5228 Table C4/65 |
99 |
|
Tracked Mobile Crane |
BS 5228 Table C4/50 |
99 |
|
Vibratory Compactor |
QPME EPD-00055 |
102 |
|
Dumper |
BS 5228 Table C4/3 |
104 |
|
Air Compressor |
BS 5228 Table D7/24 |
95 |
|
Concrete Pump |
BS 5228 Table C3/25 |
106 |
|
Piling Rig |
BS 5228 Table C3/14 |
111 |
Table 4.10 : Predicted Maximum Construction
Noise Levels at
Representative NSRs Affected by upgrading of Cheung Chau STW and Pak She SPS-
Mitigated Scenario (Quiet Plant and Site Hoardings)
|
NSR |
Description of NSR |
Predicted
Maximum Construction Noise Level |
|||
|
Works Type 4 |
Works Type 5 |
Works Type 7 |
Total |
||
|
CKH |
Cheung King House |
-- |
72 |
48 |
72 |
|
CSH2 |
Cheung Shun House |
-- |
71 |
47 |
71 |
|
PSSL |
No. 1A Pak She Second Lane |
72 |
-- |
-- |
72 |
Notes:
Noise criteria = 75 dB(A).
Works Type 4 - Upgrading of Pak She Sewage Pumping Station.
Works Type 5 - Upgrading of Cheung Chau Sewage Treatment Works.
Works Type 7 - Temporary Concrete Mixing.
Noise Mitigation Measures for Sewers Works
Level 1 Noise Mitigation Measures - Quiet PMEs and Temporary Noise Barrier
Ÿ Temporary noise barrier for stationary plant - assuming 10 dB(A) reduction on stationary plants;
Ÿ Temporary noise barrier for mobile plant - assuming 5 dB(A) reduction on mobile plants.
Table 4.11 : Noise Mitigation Measures for Certain PME
|
Description of PME |
Proposed Mitigation Measures |
Assumed Noise Reduction, dB(A) |
|
Backhoe (mini) |
Noise Barrier (Mobile) |
5 |
|
Breaker, hand-held, mass>10kg and <20kg |
Noise Barrier (Stationary) |
10 |
|
Generator |
Noise Barrier (Stationary) |
10 |
|
Poker, vibratory hand-held |
Noise Barrier (Stationary) |
10 |
|
Bar bender and cutter (electric) |
Noise Barrier (Stationary) |
10 |
|
Vibratory compactor |
Noise Barrier (Stationary) |
10 |
|
Breaker, excavator mounted (hydraulic) |
Noise Barrier (Mobile) |
5 |
|
Piling, earth auger, auger |
Noise Barrier (Stationary) |
10 |
|
Hoist (electric) |
Noise Barrier (Stationary) |
10 |
|
Excavator |
Noise Barrier (Mobile) |
5 |
|
Dumper |
Noise Barrier (Mobile) |
5 |
|
Submersible Pump |
Noise Barrier (Stationary) |
10 |
|
Rock Drill, hand-held (pneumatic) |
Noise Barrier (Stationary) |
10 |
|
Air Compressor |
Noise Barrier (Stationary) |
10 |
|
Ventilation Fan |
Noise Barrier (Stationary) |
10 |
|
Grout Mixer |
Noise Barrier (Stationary) |
10 |
|
Grout Pump |
Noise Barrier (Stationary) |
10 |
|
Winch (electric) |
Noise Barrier (Stationary) |
10 |
|
Grinder, hand held (electric) |
Noise Barrier (Stationary) |
10 |
Table 4.12 : Predicted Maximum Construction Noise
Levels at
Representative NSRs Affected by sewers works - with Level 1 Mitigation Measures
|
NSR |
Description of NSR |
Predicted Worst-case Construction Noise Level |
||||
|
Works Type 1 |
Works Type 2 |
Works Type 3 |
Works Type 6 |
Total |
||
|
TKST2 |
No. 4 Tai Kwai San Tsuen |
88 |
-- |
-- |
-- |
88 |
|
CSH1* |
Chung Shak Hei Home for the Aged |
88 |
-- |
-- |
-- |
88 |
|
CCEP |
No.7 Cheung Chau Electric Path |
88 |
-- |
-- |
-- |
88 |
|
ST |
Block D Seaview Terrence |
74 |
-- |
-- |
-- |
74 |
|
SW1 |
3A Golden Lake Garden |
74 |
-- |
66 |
-- |
75 |
|
THT |
No.24 Tai Hing Tai Road |
74 |
-- |
62 |
-- |
74 |
|
SYT1 |
No.2A Sin Yan Tseng |
82 |
-- |
-- |
-- |
82 |
|
SYT2 |
No.37 Sin Yan Tseng |
88 |
-- |
-- |
-- |
88 |
|
P1 |
No. 34 Praya Street |
-- |
84 |
-- |
60 |
84 |
|
TW1 |
Cheung Chau Fisheries Joint Association Public School |
82 |
88 |
79 |
-- |
89 |
|
TSB1 |
No. 123 Tai San Back Street |
88 |
-- |
-- |
-- |
88 |
|
LTT1 |
Cheung Chau Alliance Church |
88 |
-- |
-- |
-- |
88 |
|
LTT2 |
No.35 Lung Tsai Tsuen Road |
88 |
-- |
-- |
-- |
88 |
|
P2 |
No.41A Peak Road |
88 |
-- |
-- |
-- |
88 |
|
KYW1 |
No.31 Kwun Yam Wan Road |
71 |
-- |
-- |
-- |
71 |
|
CCS2 |
Block G-H Fu Yuen |
88 |
-- |
-- |
-- |
88 |
|
PR1 |
No.25 Peak Road |
82 |
-- |
-- |
-- |
82 |
|
PR2 |
No.72 Peak Road |
76 |
-- |
-- |
-- |
76 |
|
KYW2 |
No.46 Kwun Yam Wan Road |
82 |
-- |
-- |
-- |
82 |
|
MF1 |
Caritas Ka Fai House |
82 |
-- |
-- |
-- |
82 |
|
FP1 |
No.18 Fa Peng Road |
82 |
-- |
-- |
-- |
82 |
|
FP2 |
Bethany Cottage and House |
82 |
-- |
-- |
-- |
82 |
Notes:
NSR ID marked with * is located within the 300 m radius of the boundary of the Cheung Chau STW and Pak She SPS but no line of sight to the site.
Underlined bold figure (e.g. 77) indicates an exceedance of the 75 dB(A) noise criteria.
Noise criteria for TW1 (school) is 70 dB(A) during normal hours (65 dB(A) during examination periods).
Noise criteria for LTT1 is 70 dB(A) is a place of worship where unaided voice communication is required.
Works Type 1 - Construction of sewer (Open Cut Method).
Works Type 2 - Construction of sewer (Trenchless Method).
Works Type 3 - Upgrading of existing sewers.
Works Type 6 - Rehabilitation of existing sewers.
Level 2 Noise Mitigation Measures - Good Scheduling of Works
Level 3 Noise Mitigation Measures - Hand Digging for Excavation
Cumulative Impact
Improvement of Fresh Water Supply to Cheung Chau - Design and Construction
Replacement and Rehabilitation of Water Mains Stage 3 and Stage 4, Mains on Hong Kong and Islands – Investigation, Design and Construction
Improvement to Existing Roads and Drains in Cheung Chau Old Town, Remaining Engineering Works, Stage 3, Cheung Chau
Residual Noise Impact
Upgrading of Cheung Chau STW and Pak She SPS
Sewers Works
Table
4.13 :
Predicted Residual Impact of Works Type 1 Construction of Sewer (Open Cut
Method)
at the Representative NSRs
|
NSR |
Description of NSR |
Predicted Residual Noise
Impacts due to |
|||||
|
Stage 1 |
Stage 2 |
Stage 3 |
Stage 4 |
Stage 5 |
Stage 6 |
||
|
Duration |
|||||||
|
1.5
days |
9
days |
6
days |
2.5
days |
8
days |
3
days |
||
|
TKST2 |
No. 4 Tai Kwai San Tsuen |
88 |
84 |
80 |
83 |
84 |
80 |
|
CSH1 |
Chung Shak Hei Home for the Aged |
88 |
84 |
80 |
83 |
84 |
80 |
|
CCEP |
No.7 Cheung Chau Electric Path |
88 |
84 |
80 |
83 |
84 |
80 |
|
SYT1 |
No.2A Sin Yan Tseng |
82 |
78 |
74 |
77 |
78 |
74 |
|
SYT2 |
No.37 Sin Yan Tseng |
88 |
84 |
80 |
83 |
84 |
80 |
|
TW1 |
Cheung Chau Fisheries Joint Association Public School |
82 |
78 |
74 |
77 |
78 |
74 |
|
TSB1 |
No. 123 Tai San Back Street |
88 |
84 |
80 |
83 |
84 |
80 |
|
LTT1 |
Cheung Chau Alliance Church |
88 |
84 |
80 |
83 |
84 |
80 |
|
LTT2 |
No.35 Lung Tsai Tsuen Road |
88 |
84 |
80 |
83 |
84 |
80 |
|
P2 |
No.41A Peak Road |
88 |
84 |
80 |
83 |
84 |
80 |
|
CCS2 |
Block G-H Fu Yuen |
88 |
84 |
80 |
83 |
84 |
80 |
|
PR1 |
No.25 Peak Road |
82 |
78 |
74 |
77 |
78 |
74 |
|
PR2 |
No.72 Peak Road |
76 |
72 |
68 |
71 |
72 |
68 |
|
KYW2 |
No.46 Kwun Yam Wan Road |
82 |
78 |
74 |
77 |
78 |
74 |
|
MF1 |
Caritas Ka Fai House |
82 |
78 |
74 |
77 |
78 |
74 |
|
FP1 |
No.18 Fa Peng Road |
82 |
78 |
74 |
77 |
78 |
74 |
|
FP2 |
Bethany Cottage and House |
82 |
78 |
74 |
77 |
78 |
74 |
Notes:
Underlined bold figure (e.g. 77) indicates an exceedance of the 75 dB(A) noise criteria.
Noise criteria for TW1 (school) is 70 dB(A) during normal hours (65 dB(A) during examination periods).
Noise criteria for LTT1 is 70 dB(A) is a place of worship where unaided voice communication is required.
Works Stage 1 - Breaking up of road surface (SWL: 93 dB(A)).
Works Stage 2 - Excavation of soil material (SWL: 89 dB(A)).
Works Stage 3 - Steel fixing and concreting of manholes (SWL: 85 dB(A)).
Works Stage 4 - Laying of bedding material (SWL: 88 dB(A)).
Works Stage 5 - Backfilling and soil compaction (SWL: 89 dB(A)).
Works Stage 6 - Reinstatement of road surface (SWL: 85 dB(A)).
Table 4.14 : Predicted Residual Impact of Works Type 2 Construction of Sewer (Trenchless Method) at NSRs TW1 and P1
|
NSR |
Description of NSR |
Predicted Residual Noise Impacts due to different Construction Stages, dB(A) |
||
|
Stage 1 |
Stage 2 |
Stage 3 |
||
|
Duration |
||||
|
5 days |
7 days |
30 days |
||
|
TW1 |
Cheung Chau Fisheries Joint Association Public School |
88 |
88 |
65 |
|
P1 |
No. 34 Praya Street |
84 |
84 |
61 |
Notes:
Underlined bold figure (e.g. 77) indicates an exceedance of the 75 dB(A) noise criteria.
Noise criteria for TW1 (school) is 70 dB(A) during normal hours (65 dB(A) during examination periods).
Works Stage 1 - Excavation of pits by breaker (SWL: 108 dB(A)). This relates to the breaking up of concrete surface at grade at the pit by hydraulic breaker. Excavation below grade will require hydraulic breaker only if rock is encountered which is on occasional case only.
Works Stage 2 - Jacking of pipes (SWL: 108 dB(A)). The pits close to the two NSRs are receiving pits where the PME will be deployed after the break-through at that point. This is the worst case if rock drill is used. Predicted noise level would be less if no rock is encountered.
Works Stage 3 - Steel fixing and concreting of manholes (SWL: 85 dB(A)).
Reinstatement of road surface is by using bricks. No PME will be involved.
Table 4.15 : Predicted Residual Impact of Works Type 3
Upgrading of Existing Sewer
at NSR TW1
|
NSR |
Description of NSR |
Predicted Residual Noise Impacts due to different Construction Stages, dB(A) |
||||||
|
Stage 1 |
Stage 2 |
Stage 3 |
Stage 4 |
Stage 5 |
Stage 6 |
Stage 7 |
||
|
Duration |
||||||||
|
1.5 days |
9 days |
5 days |
6 days |
2.5 days |
8 days |
3 days |
||
|
TW1 |
Cheung Chau Fisheries Joint Association Public School |
79 |
75 |
75 |
71 |
74 |
75 |
71 |
Notes:
Underlined bold figure (e.g. 77) indicates an exceedance of the 70 dB(A) noise criteria during normal teaching hours.
Noise criteria for TW1 (school) is 65 dB(A) during examination periods.
Works Stage 1 - Breaking up of road surface (SWL: 93 dB(A)).
Works Stage 2 - Excavation of soil material (SWL: 89 dB(A)).
Works Stage 3 - Removal of existing sewers and laying of new sewers (SWL: 89 dB(A)).
Works Stage 4 - Steel fixing and concreting of manholes (SWL: 85 dB(A)).
Works Stage 5 - Laying of bedding material (SWL: 88 dB(A)).
Works Stage 6 - Backfilling and soil compaction (SWL: 89 dB(A)).
Works Stage 7 - Reinstatement of road surface (SWL: 85 dB(A)).
Noise Sources Identification
Table 4.16 : Major Noise Generating Equipment (Operational Phase)
|
Location |
Equipment |
No. of Units |
Typical Sound Power Level, dB(A) |
Sub-total Sound Power Level, dB(A) |
|
Pak She Sewage Pumping Station |
||||
|
Plant Room |
Submersible pump (Ref. 1) |
2 |
85 |
88 |
|
Exhaust fan (Ref. 2) |
2 |
79 |
82 |
|
|
Mechanically raked fine screen (Ref. 3) |
2 |
89 |
92 |
|
|
Deodourizing Units |
Deodourizing fan (Ref. 4) |
1 |
85 |
89 |
|
Cheung Chau Sewage Treatment Works |
||||
|
Preliminary Treatment Units |
Submersible pump (Ref. 1) |
10 |
85 |
95 |
|
Mechanically raked fine screen (Ref. 3) |
3 |
89 |
96 |
|
|
Deodourizing fan (Ref. 4) |
4 |
85 |
95 |
|
|
Exhaust fan (Ref. 2) |
14 |
79 |
90 |
|
|
MBR Equipment Unit (Part 1) |
Mechanically pump (Ref. 5) |
9 |
92 |
108 |
|
Deodourizing fan (Ref. 4) |
2 |
85 |
92 |
|
|
Exhaust fan (Ref. 2) |
8 |
79 |
88 |
|
|
MBR Equipment Unit (Part 2) |
Mechanically pump (Ref. 5) |
9 |
92 |
108 |
|
Deodourizing fan (Ref. 4) |
2 |
85 |
92 |
|
|
Exhaust fan (Ref. 2) |
4 |
79 |
85 |
|
|
Sludge Treatment Unit |
Submersible pump (Ref. 1) |
2 |
85 |
88 |
|
Deodourizing fan (Ref. 4) |
2 |
85 |
92 |
|
|
Exhaust fan (Ref. 2) |
6 |
79 |
87 |
|
|
Air Blower Room |
Blower (Ref. 6) |
7 |
85 |
93 |
|
Exhaust fan (Ref. 2) |
4 |
79 |
85 |
|
|
Existing Outfall Pumping Station and Header Tank |
Mechanical pump (Ref. 5) |
12 |
92 |
109 |
|
Deodourizing fan (Ref. 4) |
4 |
85 |
91 |
|
|
Exhaust fan (Ref. 2) |
14 |
79 |
90 |
|
Notes:
Only noisy equipments are included in the table. Other equipments which do not have significant noise emissions are not included.
(Ref. 1) SWL referenced to CNP283.
(Ref. 2) SWL referenced to approved EIA of Harbour Area Treatment Scheme (HATS) Stage 2A (EIA-148/2008) and Good Practices on Ventilation System Noise Control based on the flow rate of 1,300m3/hr.
(Ref. 3) SWL referenced to the approved EIA Report on Tai Po Sewage Treatment Works Stage V (EIA-097/2004).
(Ref 4) SWL of plant refers to Good Practices on Ventilation System Noise Control based on the flow rate of 17,000 m3/hr and 125 Pa.
(Ref 5) SWL of plant refer to Good Practices on Pumping System Noise Control based on the horsepower of pumpset 20 hp at 1800 rpm.
(Ref 6) SWL of plant refers to the tender specification for Shatin STW Stage 3 Upgrading and approved EIA of Harbour Area Treatment Scheme (HATS) Stage 2A (EIA-148/2008).
Noise Sensitive Receivers
Table 4.17 : Representative Noise Sensitive Receivers (Operational Phase)
|
NSR |
Description of NSR |
Nature of Use |
No. of Floor |
Figure No. |
Approximate Nearest Horizontal Separation (m) |
|
|
Cheung Chau STW |
Pak She SPS |
|||||
|
PSSL |
No. 1A Pak She Second Lane |
Residential |
3 |
4.5 |
No direct line of sight |
58 |
|
CKH |
Cheung King House |
Residential |
4 |
4.4 |
65 |
No direct line of sight |
|
CSH2 |
Cheung Shun House |
Residential |
4 |
4.4 |
81 |
No direct line of sight |
Operational Noise Impact Evaluation
Table 4.18 :
Predicted Worst-case Maximum Operational Noise Levels at
Representative NSRs - Without Mitigation Measures
|
NSR |
NSR Description |
Predicted Unmitigated Noise Level, dB(A) |
Night-time Noise Criterion, dB(A) |
Day-time Noise Criterion, dB(A) |
|
CKH |
Cheung King House |
69 |
45 |
53 |
|
CSH2 |
Cheung Shun House |
68 |
45 |
53 |
|
PSSL |
No. 1A Pak She Second Lane |
55 |
45 |
55 |
Possible Noise Mitigation Measures and Mitigated Impacts
Table 4.19 : Proposed Noise Mitigation Measures for Equipments during Operation
|
Location |
Equipment |
Mitigation Measures |
Noise Reduction |
|
Pak She Sewage Pumping Station |
Submersible pump |
enclosed inside SPS building structure |
-20 dB(A) |
|
Mechanically raked fine screen |
enclosed inside SPS building structure |
-20 dB(A) |
|
|
Deodourizing fan |
enclosed inside SPS building structure |
-20 dB(A) |
|
|
Exhaust fan |
Provide acoustic louver at discharge point |
-10 dB(A) |
|
|
Cheung Chau Sewage Treatment Works |
Submersible pump |
enclosed inside treatment unit building structure |
-20 dB(A) |
|
Mechanically raked fine screen |
enclosed inside STW building structure |
-20 dB(A) |
|
|
Deodourizing fan |
enclosed inside STW building structure |
-20 dB(A) |
|
|
Exhaust fan |
Provide acoustic louver at discharge point |
-10 dB(A) |
|
|
Blower |
enclosed inside STW building structure |
-20 dB(A) |
|
|
Mechanical pump |
enclosed inside STW building structure |
-20 dB(A) |
Table 4.20 : Predicted Maximum Operational Noise
Levels at
Representative NSRs - With Mitigation Measures
|
NSR |
NSR Description |
Predicted Mitigated Noise Level, dB(A) |
Night-time Noise Criterion, dB(A) |
Day-time Noise Criterion, dB(A) |
|
CKH |
Cheung King House |
45 |
45 |
53 |
|
CSH2 |
Cheung Shun House |
44 |
45 |
53 |
|
PSSL |
No. 1A Pak She Second Lane |
42 |
45 |
55 |
Residual Impact
Construction Phase
Operational Phase