Hong Kong-Shenzhen Western Corridor

Note: All Action and Limit Levels listed below are subject to EPD's approval

During Construction Stage

Action and Limit Levels for 1-hour and 24-hour TSP

Parameter	Location	Action Level, mg/m³	Limit Level, mg/m³
24-hour TSP	SWC-AN1	173	260
	SWC-AN2	172
1-hour TSP	SWC-AN1	322	500
	SWC-AN2	306

Action and Limit Levels (L_eq) for Construction Noise

Time Period	Action Level	Limit Level, dB(A)
		SWC-AN1	SWC-AN2
0700 – 1900 hours on normal weekdays	When one documented complaint is received from any one of the sensitive receivers	75	75

Action and Limit Levels for Marine Water Quality Monitoring

Parameter	Action	Limit
DO, mg/L	4.2	2.0
Turbidity, NTU	50.8 and 120% of upstream control station's turbidity at the same tide of the same day	101.5 and 130% of upstream control station's turbidity at the same tide of the same day
SS, mg/L	50.6 and 120% of upstream control station's SS at the same tide of the same day	86.3 and 130% of upstream control station's SS at the same tide of the same day
Note: - During mid-ebb tide, monitoring stations W2, W4, W6, W8, W10 and W16 were the impact stations, and would be compared against Action and Limit Levels (No upstream control station for W16). - During mid-flood tide, monitoring stations W1, W3, W5, W7, W9 and W15 were the impact stations, and would be compared against Action and Limit Levels (No upstream control station for W15). - Stations W11 to W14 were intended for monitoring potential cross-border water quality pollution and would not have any AL Levels.

Limit Levels for TBT

Parameter

Limit Level

TBT

0.002 uL

Note: During mid-ebb tide, monitoring stations W2, W4 and W6 are the impact stations, and would be compared against Limit Levels,

During mid-flood tides, monitoring stations W1, W3 and W5 are the impact stations, and would be compared against Limit Levels.

Trigger and Action Levels for Bird Density

Parameters

Trigger level

Action level

Bird density

(No./ha)

30% net reduction of bird density in construction site in comparison with baseline data in construction site from EIA filed surveys (Table 3.10 & 3.11 in Appendix 9A of the EIA Report) and the change of bird density in control site.

50% net reduction of bird density in construction site in comparison with baseline data in construction site from EIA filed surveys (Table 3.10 & 3.11 in Appendix 9A of the EIA Report) and the change of bird density in control site.

During Operational Stage

Proposed Criteria to be Used for Determination of Cleaning Frequency, Action Level and Action

Parameter	Reference Criteria for Determination of Cleaning Frequency	Action Level	Action
Total suspended solids (mg/L)	81	3 consecutive monitoring with the same parameter (1 or more than 1 parameter) exceeded the criteria	Increase 1 cleaning event per week
Total organic carbon (mg/L)	25
Chemical oxygen demand (mg/L)	90
Nitrite and nitrate (mg/L)	0.72
Total Kjeldahl Nitrogen (mg/L)	6.4
Total phoshorus (mg/L)	0.95
Copper (mg/L)	0.174
Lead (mg/L)	0.31
Zinc (mg/L)	0.94

Trigger and Action levels for Bird density

Parameters

Trigger level

Action

Action Level

Action

Bird density

(No./ha)

30% net reduction of bird density in the bridge in comparison with baseline data of the bridge location from EIA field surveys and the change of bird density in control site.

Increase the monitoring frequency to weekly.

50% net reduction of bird density in the bridge in comparison with baseline data of the bridge location from EIA field surveys and the change of bird density in control site.

Explore locations and measures to enhance bird feeding resources.