Appendix B – Action and Limit Levels for Water Quality Monitoring during Post-Trenching Works

 

Parameter (unit)

Water Depth

Action Level

Limit Level

Lamma Island – L-I1 and L-I2

DO

(mg/L)

Surface and Middle

4.7

4

Bottom

4.1

2

Turbidity (NTU)

Depth average

17.2

18.4

SS

(mg/L)

Depth average

10.2

10.7

Po Toi – PT-I1, PT-I2 and PT-I3

DO

(mg/L)

Surface and Middle

5.0

4

Bottom

3.3

2

Turbidity (NTU)

Depth average

14.0

21.9

SS

(mg/L)

Depth average

6.7

7.2

Ping Chau – PC-I1, PC-I2 and PC-I3

DO

(mg/L)

Surface and Middle

4.8

4

Bottom

2.9

2

Turbidity (NTU)

Depth average

11.2

13.0

SS

(mg/L)

Depth average

5.7

7.6

Notes:

-       For DO, non-compliance of the water quality limits occurs when monitoring result is lower than the limits.

-       For turbidity and SS, non-compliance of water quality limits occurs when monitoring result is higher than the limits.