Appendix 4.3 - Operation Noise Impact Assessment
Cumulative Noise Impacts from Pui O RWPS and Pui O No. 2 RWPS - Unmitigated
Option 1 (3 Main Pumps with 1 Main Pump standby in Pui O RWPS and 4 Mains Pumps in Pui O No.2 RWPS)
Option 2 (3 Main Pumps with 1 Main Pump standby in Pui O RWPS and 3 Mains Pumps with 2 trimmer pumps in Pui O No.2 RWPS)
3 Main Pumps with 1 Main Pump standby in Pui O RWPS and 4 Mains Pumps in Pui O No. 2 RWPS
NSR "LWT2"
    Potential Noise Sources Sound Power Level
for Each Equipment		 No. Total Sound
Power Level		 Distance
to Sources		 Distance Corrections Façade
Effect		 Screening Effect/
Slight Line Effect		 Acoustic Panel/
Enclosure		 Screening Effect/ Slight Line Effect/ Acoustic Louvers/ Enclosure Predicted
Noise Level		 SPL,dB(A)
Pui O RWPS 1 Four Main Pumps (3 duty + 1 standby)
@ 950kW at the "Inlet Work" (Basement)		 96 3 100.8 97 -47.7 3 -10   -10 46.1  
  2 Blower inside Blower Room 104 1 104.0 102 -48.2 3 -30   -30 28.8  
  3 Ventilation Fans - North Face 79 6 86.8 108 -48.6 3 -10   -10 31.2  
    Ventilation Fans - East Face 79 2 82.0 107 -48.5 3 -10   -10 26.5 46.3
Pui O No. 2 RWPS 1 Four Main Pumps (4 duty)
@ 950kW at the "Inlet Work" (Basement) *		 96 4 102.0 114 -49.1 3 -10 -10 -20 35.9  
  2 Blower inside Blower Room 104 1 104.0 118 -49.4 3 -30   -30 27.6  
  3 Transformers (Enclosed) 85 2 88.0 122 -49.7 3 -10 -10 31.3  
  4 Ventilation Fans - West 79 4 85.0 110 -48.8 3     39.2  
    Ventilation Fans - North (with Acoustic Louvers) 79 2 82.0 136 -50.7 3 -10 -10 -20 14.3  
  5 Roof Extractor 79 4 85.0 112 -48.9 3       39.1 43.5
Total SPL = 48.2
NSR "LWT3"
    Potential Noise Sources Sound Power Level
for Each Equipment		 No. Total Sound
Power Level		 Distance
to Sources		 Distance Corrections Façade
Effect		 Screening Effect/
Slight Line Effect		 Acoustic Panel/
Enclosure		 Screening Effect/ Slight Line Effect/ Acoustic Louvers/ Enclosure Predicted
Noise Level		 SPL,dB(A)
Pui O RWPS 1 Four Main Pumps (3 duty + 1 standby)
@ 950kW at the "Inlet Work" (Basement)		 96 3 100.8 59 -43.4 3 -10   -10 50.4  
  2 Blower inside Blower Room 104 1 104.0 47 -41.3 3 -30   -30 35.7  
  3 Ventilation Fans - North Face 79 6 86.8 59 -43.4 3 -10   -10 36.4  
    Ventilation Fans - East Face 79 2 82.0 75 -45.4 3 -10   -10 29.6 50.7
Pui O No. 2 RWPS 1 Four Main Pumps (4 duty)
@ 950kW at the "Inlet Work" (Basement) *		 96 4 102.0 133 -50.5 3 -10 -10 -20 34.5  
  2 Blower inside Blower Room 104 1 104.0 128 -50.1 3 -30   -30 26.9  
  3 Transformers (Enclosed) 85 2 88.0 130 -50.3 3 -10 -10 30.7  
  4 Ventilation Fans - West 79 4 85.0 123 -49.8 3     38.3  
    Ventilation Fans - North (with Acoustic Louvers) 79 2 82.0 140 -50.9 3 -10 -10 -20 14.1  
  5 Roof Extractor 79 4 85.0 131 -50.3 3       37.7 42.3
Total SPL = 51.3
NSR "ALWT1"
    Potential Noise Sources Sound Power Level
for Each Equipment		 No. Total Sound
Power Level		 Distance
to Sources		 Distance Corrections Façade
Effect		 Screening Effect/
Slight Line Effect		 Acoustic Panel/
Enclosure		 Screening Effect/ Slight Line Effect/ Acoustic Louvers/ Enclosure Predicted
Noise Level		 SPL,dB(A)
Pui O RWPS 1 Four Main Pumps (3 duty + 1 standby)
@ 950kW at the "Inlet Work" (Basement)		 96 3 100.8 108 -48.6 3 -10   -10 45.1  
  2 Blower inside Blower Room 104 1 104.0 109 -48.7 3 -30   -30 28.3  
  3 Ventilation Fans - North Face 79 6 86.8 99 -47.9 3     41.9  
    Ventilation Fans - East Face 79 2 82.0 95 -47.6 3       37.5 47.4
Pui O No. 2 RWPS 1 Four Main Pumps (4 duty)
@ 950kW at the "Inlet Work" (Basement) *		 96 4 102.0 125 -49.9 3 -10 -10 -20 35.1  
  2 Blower inside Blower Room 104 1 104.0 112 -49.0 3 -30   -30 28.0  
  3 Transformers (Enclosed) 85 2 88.0 109 -48.7 3 -10 -10 32.3  
  4 Ventilation Fans - West 79 4 85.0 117 -49.4 3     38.7  
    Ventilation Fans - North (with Acoustic Louvers) 79 2 82.0 101 -48.1 3 -10 -20 16.9  
  5 Roof Extractor 79 4 85.0 125 -49.9 3       38.1 42.9
Total SPL = 48.7
NSR "ALWT2"
    Potential Noise Sources Sound Power Level
for Each Equipment		 No. Total Sound
Power Level		 Distance
to Sources		 Distance Corrections Façade
Effect		 Screening Effect/
Slight Line Effect		 Acoustic Panel/
Enclosure		 Screening Effect/ Slight Line Effect/ Acoustic Louvers/ Enclosure Predicted
Noise Level		 SPL,dB(A)
Pui O RWPS 1 Four Main Pumps (3 duty + 1 standby)
@ 950kW at the "Inlet Work" (Basement)		 96 3 100.8 147 -51.3 3 -10   -10 42.4  
  2 Blower inside Blower Room 104 1 104.0 153 -51.7 3 -30   -30 25.3  
  3 Ventilation Fans - North Face 79 6 86.8 141 -51.0 3     38.8  
    Ventilation Fans - East Face 79 2 82.0 132 -50.4 3       34.6 44.5
Pui O No. 2 RWPS 1 Four Main Pumps (4 duty)
@ 950kW at the "Inlet Work" (Basement) *		 96 4 102.0 139 -50.8 3 -10 -10 -20 34.2  
  2 Blower inside Blower Room 104 1 104.0 128 -50.1 3 -30   -30 26.9  
  3 Transformers (Enclosed) 85 2 88.0 124 -49.8 3 -10 -10 31.2  
  4 Ventilation Fans - West 79 4 85.0 135 -50.6 3     37.4  
    Ventilation Fans - North (with Acoustic Louvers) 79 2 82.0 111 -48.9 3 -10 -20 16.1  
  5 Roof Extractor 79 4 85.0 139 -50.9 3       37.2 41.8
Total SPL = 46.4
Remark:
SPL for Main Pump at 1m = 88 dB(A), provided by WSD
SWL for Blowers inside blower room = 104 dB(A), refer to "Outlying Islands Sewerage Stage Phase 1 - Ngong Ping Sewage Treatment Works and Sewerage Investigation"
SWL for Transformer = 85 dB(A), refer to "San Wai STW and Ha Tsuen PS -EIA"
* Acoustic Louvres provided for ventilation openings of pump hall