Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau
(2009-2013) - Investigation
28th MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA
CHAU October 2011
1.1
Background
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. CMP IVc is
presently in operation for backfilling by contaminated mud and is anticipated
to reach its capacity in 2011. A series
of four newly constructed seabed pits at the East of Sha
Chau area, CMP Va-d, will
be provided for the disposal of contaminated mud after CMP IVc
is full. Dredging operations were
completed for the construction of CMP Va-b and are
now taking place to construct CMP Vc. The environmental monitoring and audit
(EM&A) programme for the CMPs at the East of Sha Chau area presently covers
disposal and capping operations at CMP IV and dredging operations at CMP Vc.
1.2
Reporting
Period
This Monthly Progress Report
covers the monitoring period of October 2011.
1.3
Details
of Sampling and Laboratory Testing Activities
After the Typhoon Nesat visited
For CMP V, sampling for Impact Water Quality Monitoring during
Dredging Operations was conducted on 18
October 2011. A summary of field activities are presented in Annex A.
A summary of monitoring data
submitted by the Contractor in this reporting month is presented in Table 1.1.
Table 1.1 Summary
of monitoring data submitted by the Contractor during the reporting month
|
Key
Task |
Monitoring
Component |
Results Received from the Contractor |
|
CMP
IV |
|
|
|
Demersal Trawling |
Marine Biota |
11, 12 August
2011 sampling: 20 October 2011 |
|
CMP V |
|
|
|
Impact
Monitoring during Dredging Operations |
Water Quality |
September 2011 sampling: 20 October 2011 |
|
|
|
|
1.4
Details
of Outstanding Sampling and / or Analysis
No outstanding sampling and laboratory analysis remained from October 2011.
1.5
Brief
Discussion of the Monitoring Results
Results of Impact
Water Quality Monitoring during Dredging Operations of CMP V for October
2011 are presented for CMP V. Detailed
results will be discussed in the 10th
Quarterly Report.
1.5.1
CMP V
Impact Water Quality
Monitoring during Dredging Operations of CMP V – October 2011
Impact
Water Quality Monitoring during Dredging Operations of CMP V was conducted
on 18 October 2011. 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 V. 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).
Monitoring results are
presented in Table B1 of Annex B. Levels
of Dissolved Oxygen (DO), Turbidity and Total Suspended Solids (TSS) generally complied
with the Action and Limit Levels set in the Baseline
Monitoring Report ([1]). Levels of TSS
and Turbidity exceeded the Action and Limit Levels, respectively, in the
downstream station DS1 during the mid-flood tide. Station DS1 is located on the edge of the
works area of CMP Vc and the compliance of Action and
Limit Levels at other downstream stations outside the works area (ie DS2-4) would indicate that there is no evidence of any
unacceptable adverse water quality impacts outside the dredging works area of CMP
Vc. In
addition, level of TSS at upstream station US2, which is approximately 500 m
from the works area and unlikely to be affected by the dredging works, was
slightly higher than station DS1 during the mid-flood tide. Similar TSS levels between the two stations would
indicate that the high TSS levels are more likely to be caused by natural
background fluctuations in water quality which affected both upstream and
downstream area rather than indicating any adverse water quality impacts from
the dredging operations.
Overall, there appears to
be no unacceptable water quality impacts causing by the dredging operations at
CMP Vc and no additional measures are thus considered
required.
1.6
Activities
Scheduled for the Next Month
Impact
Water Quality Monitoring during Dredging Operations will be undertaken for CMP V in November 2011. No monitoring activities are scheduled for
CMP IV in the next reporting month.
The sampling schedule is presented in Annex A.
1.7
Study
Programme
A summary of the Study Programme is presented in Annex C.