Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau
(2009-2013) - Investigation
41st
MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU November 2012
1.1
Background
1.1.1
Since 1992,
the East of Sha Chau 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 November 2012, 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
· The dredging of CMP Vd was in progress.
1.1.2
The
Environmental Monitoring and Audit (EM&A) programme for the CMPs at the
East of Sha Chau area (ESC) presently covers the above operations.
1.2
Reporting Period
This Monthly
Progress Report covers the monitoring period of November 2012.
1.3
Details of Sampling and Laboratory Testing
Activities
1.3.1
The following
monitoring activities have been undertaken for CMP V in November 2012:
· Routine
Water Quality Monitoring was
conducted on 5 November 2012;
· Water
Column Profiling was conducted
on 6 November 2012;
· Impact
Water Quality Monitoring during Dredging Operations was conducted on 7 November
2012; and
· Pit
Specific Sediment Chemistry was
conducted on 8 November 2012.
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 analysis of Pit
Specific Sediment Chemistry was 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.
1.5.2
Brief
discussion of the monitoring results is presented in this section. Detailed discussion will be presented in
the corresponding Quarterly Report.
Table 1.1 Monitoring
activities in November 2012
|
Monitoring
activities |
Date of
Monitoring |
Monitoring results presented in this report? |
|
Routine Water Quality
Monitoring for CMP Va |
5 November 2012 |
Yes |
|
Water Column Profiling for
CMP Va |
6 November 2012 |
Yes |
|
Impact Water Quality
Monitoring during Dredging Operations of CMP Vd |
7 November 2012 |
Yes |
|
Pit Specific Sediment
Chemistry Monitoring for CMP Va |
8 November 2012 |
No.
Laboratory analysis yet to be completed during preparation of this
monthly report. |
1.5.3
Impact Water Quality Monitoring during Dredging Operations of CMP Vd – November 2012
1.5.4
Impact Water Quality Monitoring
during Dredging Operations of CMP Vd was
conducted on 7 November 2012. 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 the 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).
1.5.5
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]).
1.5.6
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).
1.5.7
Water Column Profiling for CMP Va
– November 2012
In-situ Measurements
1.5.8
Water Column Profiling was
undertaken at a total of two sampling stations in November 2012. The water quality monitoring results for November 2012 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 dry season period (November to March) of 1999-2010 from stations
in the Northwestern Water Control Zone, where CMPs are located. For Salinity, the average value obtained
from the Upstream station was used for the basis as
the WQO. Graphical presentation of
the monitoring results is provided in Annex C.
1.5.9
Analyses of results for November
2012 indicated that levels of Salinity, pH and DO all complied with the WQOs at
both Upstream and Downstream stations (Figures 1
– 3 of Annex C). DO and Turbidity
complied with the Action and Limit Levels set in the EM&A
Manual ([2]).
Laboratory Measurements for Suspended Solids (SS)
1.5.10
Analyses of data obtained in
November 2012 indicated that the SS levels at both Upstream and Downstream
stations complied with the WQO (Figure 4 of Annex C). Also, SS levels at all
stations measured in November 2012 complied with the Action and Limit Levels
set in the EM&A Manual.
1.5.11
Overall, the results indicated that
the mud disposal operation at CMP Va did not appear to cause any deterioration
in water quality during this reporting period.
1.5.12
Routine Water Quality Monitoring for CMP Va – November 2012
1.5.13
The results
for the Routine Water Quality Monitoring conducted during November 2012 in the dry season
have been assessed for compliance with the WQOs set by
EPD as presented in Section 1.5.8 above (please
see Figure 1.2 for the monitoring locations).
In-situ
monitoring and laboratory results are shown in Table
1.2 and 1.3, respectively, with graphical presentation provided
in Annex C.
Monitoring was undertaken at a total of ten stations in the reporting
month.
In-situ Measurements
1.5.14
Analyses of results
for November 2012 indicated that for all stations (Impact, Intermediate and
Reference), levels of pH, DO and salinity complied with the WQOs (Figures 5-8 of Annex C). Levels
of DO and Turbidity within the reporting month complied with the Action and
Limit Levels set in the EM&A Manual ([3])
(Figure
1.5.15
s 6 and 9 of Annex C). All in-situ water quality measurements showed
relatively minor variations amongst Impact, Intermediate and Reference stations
(Figures 5 to 9 of Annex C).
Laboratory Measurements
1.5.16
Analyses of
November 2012 results indicate that concentrations of Cadmium, Mercury and
Silver were below their limit of reporting at all stations. Arsenic, Copper, Lead, Nickel and Zinc
were detected in samples from all stations (Figures
10 and 11 of Annex C).
Concentrations of Arsenic, Chromium, Lead and Nickel appeared to be
similar amongst all stations while concentration of Zinc was the highest at
Reference stations. Levels of 5-day
Biochemical Oxygen Demand (BOD5), Total Inorganic Nitrogen (TIN) and
NH3-N were similar amongst all stations (Figures
12 and 13 of Annex C).
Concentrations of SS exceed WQO (15.34 mg/L for dry season) at Impact
and Intermediate Stations while all of them complied with the Action and Limit
Levels at all stations within the reporting month (Figure
14 of Annex C).
Table 1.2 In-situ Monitoring
Results for Routine Water Quality Monitoring during November 2012
|
Stations |
Temp |
Salinity |
Turbidity |
pH |
Dissolved Oxygen |
|
|
|
(°C) |
|
(NTU) |
|
(%) |
(mg L-1) |
|
RFE (Reference) |
24.86 |
29.05 |
6.89 |
7.53 |
90.06 |
6.33 |
|
IPE (Impact) |
24.96 |
29.84 |
9.57 |
7.67 |
88.10 |
6.15 |
|
INE (Intermediate) |
25.04 |
29.78 |
9.02 |
7.48 |
86.54 |
6.03 |
|
Ma Wan Station |
25.09 |
30.74 |
6.04 |
7.54 |
84.74 |
5.88 |
|
WQO |
N/A |
26.15-31.96 |
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 during November 2012
|
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) |
|
RFE |
1.96 |
<LOR |
<LOR |
0.67 |
10.58 |
<LOR |
1.29 |
3.08 |
19.50 |
0.04 |
0.55 |
1.24 |
13.75 |
|
IPE |
2.00 |
<LOR |
<LOR |
1.15 |
5.67 |
<LOR |
0.88 |
2.25 |
7.38 |
0.04 |
0.46 |
0.91 |
16.38 |
|
INE |
2.08 |
<LOR |
<LOR |
0.63 |
6.96 |
<LOR |
0.90 |
2.04 |
11.50 |
0.05 |
0.49 |
1.00 |
15.46 |
|
Ma Wan Station |
1.88 |
<LOR |
<LOR |
1.00 |
5.50 |
<LOR |
1.19 |
2.25 |
15.50 |
0.06 |
0.39 |
1.51 |
13.50 |
|
WQO of SS |
15.34 |
||||||||||||
1.5.17
Overall, the
results indicated that the disposal operation at CMP Va did not appear to cause
any deterioration in water quality during this reporting period.
1.6
Activities Scheduled for the Next Month
1.6.1
The following
monitoring programmes will be conducted in the next monthly period of December
2012:
CMP V
·
Pit Specific Sediment Chemistry for CMP Va;
·
Cumulative Impact Sediment Chemistry for CMP Va;
·
Water Column Profiling for CMP Va; and
·
Impact Water Quality Monitoring during Dredging
Operations for CMP Vd.
1.6.2
The sampling
schedule is presented in Annex A.
1.7
Study Programme
A summary of the Study Programme is presented in Annex D.