Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau (2009-2013) - Investigation
5th
MONTHLY PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU - November 2009
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 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.
1.2
Reporting Period
This Monthly Progress Report
covers the monitoring period of November 2009.
1.3
Details of Sampling and
Laboratory Testing Activities
No sampling was scheduled for CMP IV during November 2009. For CMP V, samplings for Water Column Profiling and Impact Monitoring during Dredging Operations
were conducted on 25th and 26th November 2009,
respectively. 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 on 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 |
|
|
|
Water Sampling and Chemical Analysis |
a) Water column profiling |
August’s
sampling: 18 November 2009 |
|
|
b) Routine water quality monitoring |
August’s sampling:
18 November 2009 |
|
Demersal Trawling and Tissue Analysis |
a) Demersal trawling |
July’s sampling:
18 November 2009 |
|
|
|
August’s
sampling: 18 November 2009 |
|
Sediment Sampling and Chemical Analysis |
a) Pit Specific Sediment Chemistry |
August’s
sampling: 18 and 26 November 2009
|
|
|
b) Cumulative Impact Sediment Chemistry |
August’s
sampling: 18 and 26 November 2009
|
|
|
c) Sediment Chemistry after a Major Storm Event |
July’s sampling:
30 November 2009 (PSD data) |
|
|
|
August’s
sampling: 18 and 26 November 2009
|
|
Benthic
Recolonisation Study |
|
August’s
sampling: 16 November 2009 |
|
CMP V |
|
|
|
Water Sampling
and Chemical Analysis |
a) Baseline
Water Quality Monitoring |
August’s sampling:
30 November 2009 (Chromium data) |
|
|
|
|
1.4
Details of Outstanding
Sampling and / or Analysis
No outstanding sampling remained from November 2009. Laboratory analysis of chemical contents
in tissue and whole body samples of biota collected in July and August 2009 are
still in progress.
1.5
Brief Discussion of the
Monitoring Results
For CMP IV, monitoring results for Sediment
Chemistry after a Major Storm Event for September 2009 are presented
below. Further for CMP V,
monitoring results are presented for Water Column
Profiling for September and November 2009 and Impact Monitoring during Dredging Operations for November
2009. Detailed results will be
discussed in the relevant Quarterly
Reports.
1.5.1
Sediment Chemistry after a Major Storm Event for CMP
IV (Koppu)
Sampling for Sediment Chemistry
after a Major Storm Event was conducted on 19th September 2009
after the visit of Tropical Cyclone Koppu,
which led to the issue of No. 8 Gale or
Storm Signal on 15th September 2009. The track of Koppu is shown in Figure 1.1.
|
|
Figure 1.1 Track of
Tropical Cyclone Koppu from 12-16 September 2009 (Source:
Concentrations of all metals, except Arsenic, were below the Lower Chemical Exceedance Limit (LCEL) and Upper Chemical Exceedance Limit (UCEL) (Figures 1 and 2 of Annex B). Concentrations of Arsenic in sediments
from all stations exceeded LCEL (12
mg/kg), but remained below UCEL (42
mg/kg).
Moisture content in the sediments from all stations ranged between 39.97
– 57.98 % (Figure 3 of Annex B). Sediments were mostly composed of silt
and clay materials (73 - 97 %; Figure 4
of Annex B).
1.5.2
Water Column Profiling for CMP V during September 2009
Results of Water Column Profiling
for September 2009 show that salinity, pH and Dissolved Oxygen (DO) all
complied with the Water Quality Objectives (WQOs) at both Upstream and
Downstream stations (Figures 6 to 8 of Annex B). However, levels of Total Suspended
Solids (TSS) exceeded the WQO at both Upstream and Downstream stations (Figure 5 of Annex
B).
1.5.3
Water Column Profiling for CMP V during November 2009
Results of Water Column Profiling
for November 2009 show that salinity, pH and DO all compiled with the WQOs at
both Upstream and Downstream stations (Figures
10 to 12 of Annex
B). However,
levels of TSS exceeded the WQO at both Upstream and Downstream stations (Figure 9 of Annex
B).
1.5.4
Impact Monitoring during Dredging Operations of CMP V
– November 2009
Impact
Monitoring during Dredging Operations of CMP V was conducted on 26th November 2009. 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 and water samples were taken from three water depth
levels of the water column which were surface (1m below sea surface), mid-depth
and bottom (1m above the seabed).
Monitoring results are presented in Figures
13 to 16 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).
1.6
Activities Scheduled for the
Next Month
Pit Specific Sediment Chemistry, Sediment Toxicity
Monitoring, Benthic Macro In-fauna Sampling, Cumulative Impact Sediment
Chemistry Monitoring and Water Column Profiling will be
conducted for CMP IV in the next monthly period. Water
Column Profiling and Impact
Monitoring during Dredging Operations will be conducted for CMP V during
the next monthly period. The
sampling schedule is presented in Annex A.
1.7
Study Programme
A summary of Study programme is presented in Annex
C.