Table 3.2d Action and Limit
Levels for Water Quality
Parameter
(unit) |
Water Depth |
Action Level |
Limit Level |
Dissolved Oxygen (mg/L)
(surface, middle, bottom) |
Surface and Middle |
5.0 |
4.2 except 5 for FCZ |
Bottom |
4.7 |
3.6 |
|
Turbidity (NTU) |
Depth average |
Before 25 Mar 13: 27.5 or 120% of upstream control station¡¯s
turbidity at the same tide of the same day On or After 25 March 13: 27.5 and 120% of upstream control station¡¯s
turbidity at the same tide of the same day |
Before 25 Mar 13: 47.0 or
130% of turbidity at the
upstream control station at the same tide of same day On or After 25 March 13: 47.0 and 130% of turbidity at the upstream control
station at the same tide of same day |
Suspended Solids (mg/L) |
Depth average
|
Before 25 Mar 13: 23.5
or 120% of upstream
control station¡¯s SS at the same tide of the same day On or After 25 March 13: 23.5
and 120% of upstream
control station¡¯s SS at the same tide of the same day |
Before 25 Mar 13: 34.4 or 130% of SS at the upstream control station at
the same tide of same day and
10mg/L for WSD Seawater Intakes On or After 25 March 13: 34.4 and 130% of SS at the upstream control station at
the same tide of same day and
10mg/L for WSD Seawater Intakes |
Note:
(1) Depth-averaged is
calculated by taking the arithmetic means of reading of all three depths
(2) For DO, non-compliance of the water quality limit occurs when
monitoring result is lower that the limit.
(3) For SS & turbidity non-compliance of the water quality limits
occur when monitoring result is higher than the limits.
(4) All the figures given in the table are used for reference only and
the EPD may amend the figures whenever it is considered as necessary.
(5) The 1%-ile of baseline data for dissolved
oxygen (surface and middle) and dissolved oxygen (bottom) are 4.2mg/L and
3.6mg/L respectively.
(6) The proposal for changing Action and Limit Levels for water quality
monitoring was submitted to EPD on 15 March 2013. No objection was received
from EPD according to the letter (ref. (10) in Ax(3) to EP2/G/A/129pt.4)
dated 25 March 2013. Therefore, the updated Action and Limit Levels for water
quality monitoring was used for comparison starting from 25 March 2013.