Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau (2009-2013) - Investigation
11th
MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU - May 2010
1.2
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 2010.
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 are now
taking place to construct CMP Va. The
environmental monitoring and audit (EM&A) programme for the CMPs at the
East of Sha Chau area presently covers disposal operations at CMP IVc and
dredging operations at CMP V.
1.3
Reporting Period
This Monthly
Progress Report covers the monitoring period of May 2010.
1.4
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 2010. 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 V |
|
|
|
Water Sampling
and Chemical Analysis |
Impact
Monitoring during Dredging Operations |
May’s
sampling: 24 May 2010 |
1.5
Details of Outstanding Sampling and / or Analysis
No outstanding sampling and laboratory analysis
remained from May 2010.
1.6
Brief Discussion of the Monitoring Results
Results of Pit
Specific Sediment Chemistry for April 2010 are presented for CMP IV. Results of Impact Water Quality Monitoring during Dredging Operations for May
2010 are presented for CMP V. Detailed
results will be discussed in the relevant Quarterly
Reports.
1.6.1
CMP IV
Pit Specific Sediment Chemistry for CMP IV during
April 2010
Concentrations of metals at all
stations were below the Lower Chemical
Exceedance Level (LCEL), with the exception of Arsenic (Figures 1 and 2 of Annex B).
Concentrations of Arsenic slightly exceeded the LCEL at all Near Pit and Pit Edge stations.
No metal concentrations exceeded the UCEL (Figures 1 and 2 of Annex B).
Concentrations
of Total DDT and 4,4” DDE were higher than the detection limits at the Pit-Edge
station CPA (Figure 3 of Annex B). Total
Organic Carbon (TOC) concentration in the sediment was the highest at the
Pit-Edge station CPB when compared to other stations (Figure 4). Sediments were
mainly composed of silt and clay (65.0 – 95.5 %) materials with the exception
of Pit-Edge station CPA, in which sediments were mainly composed of sand (63 %;
Figure 5).
Concentrations of
Low Molecular Weight (LMW) Polyaromatic Hydrocarbons (PAHs), High Molecular
Weight (HMW) PAHs, Total PAHs,
Polychlorinated Biphenyls (PCBs) and TBT were below detection limits in
sediment samples collected from all stations.
1.6.2
CMP V
Impact Water Quality Monitoring during Dredging
Operations of CMP V – May 2010
Impact Water Quality Monitoring during Dredging Operations of CMP V
was conducted on 24 May 2010. 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 Figures 6 to 9 of Annex B. Levels of DO, depth-average Turbidity and TSS
complied with the Action and Limit Levels set in the Baseline Monitoring Report ([1]) (Tables B1 and B2 of Annex B).
1.7
Activities Scheduled for the Next Month
The following monitoring
activities will be
conducted in the next monthly period of June 2010:
·
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.
1.8
Study Programme
A summary of the Study programme is presented in Annex C.