Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau (2009-2013) - Investigation
47TH
MONTHLY PROGRESS REPORTFOR CONTAMINATED MUD PITS AT SHA CHAU MAY 2013
1.1
Background
1.1.1
Since 1992,
the East of Sha Chau (ESC) area has been the site of a series of dredged
contaminated mud pits (CMPs) designed to provide confined marine disposal
capacity for contaminated mud arising from the HKSAR’s dredging and reclamation
projects. In May 2013, the following
works were being undertaken at the CMPs:
·
Capping
was being undertaken at CMP IVc;
·
Disposal
of contaminated mud was taking place at CMP Va; and
·
Dredging
of CMP Vd was in progress and completed on 15 May 2013.
1.1.2
The
Environmental Monitoring and Audit (EM&A) programme for the CMPs at the ESC
area presently covers the above operations.
1.2
Reporting
Period
1.2.1
This Monthly Progress
Report covers the monitoring period of May 2013.
1.3
Details of
Sampling and Laboratory Testing Activities
1.3.1
The following
monitoring activities have been undertaken for CMP V in May 2013:
·
Impact Water Quality Monitoring during Dredging Operations for CMP Vd was conducted on 7 May
2013;
·
Pit Specific Sediment Chemistry was conducted for CMP Va on 14 May 2013;
·
Routine Water Quality Monitoring was conducted for CMP Va on 16 May 2013; and
·
Water Column Profiling was scheduled to be undertaken on 28 May 2013. However, there was no dumping activity at CMP
Va while the monitoring team was on-site.
As such, in-situ measurements
and water sampling were not undertaken for Water
Column Profiling in May 2013.
1.3.2
A summary of field activities are presented in Annex A.
1.4
Details of
Outstanding Sampling and / or Analysis
1.4.1
No outstanding
sampling remained and laboratory analyses of Pit
Specific Sediment Chemistry conducted in April
and May 2013 were yet to be
completed during preparation of this monthly report.
1.5
Brief
Discussion of the Monitoring Results for CMP V
1.5.1
Table 1.1 summarises the
monitoring results that are presented in the current monthly report. Brief
discussion of the monitoring results is presented in this section. Detailed discussion will be presented in the
corresponding Quarterly Report.
|
Monitoring
activities |
Date of
Monitoring |
Monitoring results presented in this report? |
|
Pit Specific
Sediment Chemistry Monitoring for CMP Va |
23 Apr 2013 |
No.
Laboratory analysis yet to be completed during preparation of this
monthly report. |
|
|
14 May 2013 |
No.
Laboratory analysis yet to be completed during preparation of this
monthly report. |
|
Impact Water
Quality Monitoring during Dredging Operations of CMP Vd |
7 May 2013 |
Yes |
|
|
|
|
|
Water Column Profiling for CMP Va |
28 May 2013 |
No. In-situ measurements
and water sampling were not undertaken as there was no dumping activity on
the monitoring day |
|
|
|
|
|
Routine Water
Quality Monitoring for CMP Va |
16 May 2013 |
Yes |
Table 1.1 Monitoring
activities in April / May 2013
1.5.2
Impact Water Quality Monitoring during Dredging Operations of CMP Vd – May
2013
1.5.3
Impact Water Quality Monitoring
during Dredging Operations of CMP Vd was
conducted on 7 May 2013. On the survey day,
sampling was conducted during both mid-ebb and mid-flood tides at two Reference
(Upstream) stations upstream and five Impact (Downstream) stations downstream
of the dredging operations at CMP Vd (Figure 1.1). Monitoring
was also conducted at Ma Wan station. At
each station, in-situ
measurements of water quality parameters as well as water samples were taken
from three depths in the water column (ie surface: 1 m below sea surface,
mid-depth and bottom: 1 m above the seabed).
Where water depth was less than 6 m, the
mid-depth station was omitted. If water
depth was less than 3 m, only the mid-depth station was monitored.
1.5.4
Monitoring
results are presented in Table B1 of Annex B. Levels of Dissolved Oxygen (DO), Turbidity
and Suspended Solids (SS) complied with the Action and Limit Levels set in the
Baseline Monitoring Report ([1]).
1.5.5
Overall, there
appears to be no unacceptable water quality impacts causing by the dredging
operations at CMP Vd and no additional measures are thus considered required
except for those stated in the Environmental Permit (EP-312/2008).
1.5.6
Routine Water Quality Monitoring for CMP Va – May2013
1.5.7
The results
for the Routine Water Quality Monitoring conducted during May 2013 in the wet
season have been assessed for compliance with the Water Quality Objectives (WQOs)
set by Environmental Protection Department (EPD). This consists of a review of the EPD routine water quality monitoring
data for the wet season period (April to October) of 1999-2010 from stations in
the Northwestern Water Control Zone, where the CMPs are located. For Salinity, the average value obtained from
the Upstream Station was used for the basis as the WQO. In-situ monitoring and laboratory results are shown in Tables 1.2 and 1.3, respectively, with graphical presentation provided
in Annex C. Monitoring
was undertaken at a total of 10 stations in the reporting month (see Figure 1.2).
In-situ
Measurements
1.5.8
Analysis of
results for May 2013 indicated that for all stations (Impact, Intermediate, Reference
and Ma Wan), levels of pH and DO complied with the WQOs (Figures 1 and 2 of Annex C). Levels of
Salinity complied with the WQO at all stations, except at Ma Wan Station (Figure 4 of Annex C). The higher
salinity recorded at Ma Wan station is likely to be caused by its greater
separation distance from the Pearl River mouth, which is a key source of
freshwater inputs in the area, when compared to the Reference stations. Levels of DO and Turbidity within the reporting
month complied with the Action and Limit Levels set in the EM&A Manual ([2]) (Figures 2 and 5 of Annex C). All in-situ water quality measurements showed
relatively minor variations amongst Impact, Intermediate and Reference stations
(Figures 1-5 of Annex C).
Laboratory
Measurements
1.5.9
Analyses of May
2013 results indicate that concentrations of Arsenic, Cadmium, Chromium, Lead,
Mercury and Silver were below their limit of reporting at all stations while
Copper, Nickel and Zinc were detected in samples from all stations. Concentrations of Copper and Zinc were slightly
higher at Impact stations while concentrations of Nickel were similar amongst
all stations (Figure 6 of Annex C). Levels of
5-day Biochemical Oxygen Demand (BOD5), Total Inorganic Nitrogen
(TIN) and Ammoniacal-Nitrogen (NH3-N) were similar amongst all
stations (Figures 7 and 8 of Annex C). Concentrations of SS complied with the WQO (12.74
mg/L for wet season) and Action and Limit Levels at all stations during the
reporting month (Figure 9 of Annex C).
1.5.10
Overall, the
results indicated that the disposal operation at CMP Va did not appear to cause
any unacceptable deterioration in water quality during this reporting period.
Table 1.2 In-situ
Monitoring Results for Routine Water Quality Monitoring of CMP Va in May 2013
|
Stations |
Temp |
Salinity |
Turbidity |
pH |
Dissolved Oxygen |
|
|
|
(°C) |
|
(NTU) |
|
(%) |
(mg L-1) |
|
RFF (Reference) |
25.24 |
22.24 |
3.19 |
7.70 |
87.45 |
6.34 |
|
IPF (Impact) |
25.13 |
23.14 |
2.41 |
7.76 |
85.67 |
6.19 |
|
INF (Intermediate) |
25.05 |
23.13 |
1.89 |
7.75 |
84.84 |
6.14 |
|
Ma Wan Station |
24.45 |
26.88 |
1.36 |
7.72 |
87.39 |
6.26 |
|
WQO |
N/A |
20.01-24.46# |
N/A |
6.5-8.5 |
N/A |
>4 |
|
Note: #Not exceeding 10% of natural
ambient level which is the result obtained from the Reference Station. |
||||||
Table 1.3 Laboratory
Results for Routine Water Quality Monitoring of CMP Va in May 2013
|
Stations |
As (µg/L) |
Ag (µg/L) |
Cd (µg/L) |
Cr (µg/L) |
Cu (µg/L) |
Hg (µg/L) |
Pb (µg/L) |
Ni (µg/L) |
Zn (µg/L) |
NH3-N (mg/L) |
TIN (mg/L) |
BOD5 (mg/L) |
SS (mg/L) |
|
|
|
RFF |
<LOR |
<LOR |
<LOR |
<LOR |
2.83 |
<LOR |
<LOR |
4.17 |
4.58 |
0.19 |
1.25 |
1.03 |
6.04 |
|
|
|
IPF |
<LOR |
<LOR |
<LOR |
<LOR |
6.54 |
<LOR |
<LOR
|
3.83 |
6.67 |
0.19 |
1.15 |
0.78 |
3.58 |
|
|
|
INF |
<LOR |
<LOR |
<LOR |
<LOR |
2.13 |
<LOR |
<LOR |
3.83 |
2.25 |
0.19 |
1.16 |
0.82 |
4.63 |
|
|
|
Ma Wan Station |
<LOR |
<LOR |
<LOR |
<LOR |
3.63 |
<LOR |
<LOR |
3.38 |
7.13 |
0.17 |
0.80 |
0.90 |
4.63 |
|
|
|
|
WQO
of SS: 12.74 mg/L |
|
|||||||||||||
|
Note: LOR = Limit Of Reporting |
|
||||||||||||||
1.6
Activities
Scheduled for the Next Month
1.6.1
The following
monitoring activities will be conducted in the next monthly period of June 2013
for CMP V:
·
Pit Specific Sediment Chemistry for CMP Va;
·
Cumulative Impact Sediment Chemistry for CMP Va; and
·
Water Column Profiling for CMP Va.