Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau
(2009-2013) - Investigation
23rd MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA
CHAU (for May 2011)
June 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 and are now
taking place to construct CMP Vb. 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 Vb.
1.2
Reporting
Period
This Monthly Progress Report
covers the monitoring period of May 2011.
1.3
Details
of Sampling and Laboratory Testing Activities
No sampling activity was conducted for CMP IVc
during the reporting period. For CMP V, sampling for Impact Water Quality Monitoring during Dredging Operations was conducted on 24 May 2011.
A summary of field activities are presented in Annex A.
A summary of laboratory analysis results submitted by the Contractor in
this reporting month is presented in Table
1.1.
Table 1.1 Summary
of laboratory analysis results submitted by the Contractor during the reporting
month
|
Key Task |
Monitoring Component |
Results Received from the Contractor |
|
CMP IV |
|
|
|
Pit-Specific
Sediment Chemistry |
Sediment Quality |
February 2011
sampling: 5 May 2011 |
|
CMP V |
|
|
|
Impact
Monitoring during Dredging Operations |
Water Quality |
March 2011
sampling: 31 May 2011 |
1.4
Details
of Outstanding Sampling and / or Analysis
No outstanding sampling and laboratory analysis remained from May 2011.
1.5
Brief
Discussion of the Monitoring Results
Results of Pit
Specific Sediment Chemistry for April 2011 are presented for CMP IV and results
of Impact Water Quality Monitoring during
Dredging Operations for May 2011 are presented for CMP V. Detailed results will be discussed in the 8th Quarterly Report.
1.5.1
CMP IV
Pit Specific Sediment
Chemistry for CMP IV during April 2011
Cadmium, Chromium, Lead, Mercury and Nickel, were all below their Lower Chemical Exceedance
Levels (LCELs; Figures B1 and
B2 of Annex B) at all stations.
Arsenic,
concentrations exceeded
the LCEL at both Near-Pit and both Pit-Edge stations but at none of the
Active-Pit stations.
Three exceedances occurred
at Active-Pit station NCA. These were an
LCEL exceedance for Copper (123 mg/kg) and UCEL exceedances for Zinc and Silver (323 mg/kg and 5 mg/kg
respectively).
Concentrations of Total DDT
and 4,4” DDE (DDE) were only
detectable at Pit-Edge station CPB (Figure
B3 of Annex B). Sediment concentrations of
Total Organic Carbon (TOC) were relatively consistent amongst all stations (Figure B4 of Annex B) with
the exception of Active-Pit station NCA where approximately twice the levels
measured at other Impact, as well as Reference and Intermediate stations. With the exception of stations CPA and NCB
which had higher sand contents, sediment samples were mainly composed of silt
and clay materials (72 – 92 %; Figure B5 of
Annex B).
1.5.2
CMP V
Impact Water Quality
Monitoring during Dredging Operations of CMP V – May 2011
Impact
Water Quality Monitoring during Dredging Operations of CMP V was conducted
on 24 May 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) complied
with the Action and Limit Levels set in the Baseline
Monitoring Report ([1]). Therefore,
there appears to be no evidence of any unacceptable adverse water quality
impacts arising from the dredging operations of CMP V at ESC.
1.6
Activities
Scheduled for the Next Month
The following monitoring activities will be conducted in the next monthly period of June 2011:
·
Water Column Profiling for CMP IV;
·
Water Quality Monitoring during Capping for CMP IV; and,
·
Impact Water Quality Monitoring during Dredging
Operations for CMP V.
The sampling schedule is presented in Annex A.
1.7
Study
Programme
A summary of the Study programme is presented in Annex C.