Agreement No. CE 4/2009 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pit at Sha Chau
(2009-2013) - Investigation
8th MONTHLY
PROGRESS REPORT FOR CONTAMINATED MUD PITS AT SHA CHAU - February 2010
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 February 2010.
1.3
Details
of Sampling and Laboratory Testing Activities
Field sampling activities conducted in this monthly period for CMP IVc are listed below:
· Routine Water Quality Monitoring was conducted on 4
February 2010;
· Water Column Profiling was conducted on 5 February 2010;
and,
· Demersal Trawling was conducted on 25 and 26 February 2010.
For CMP V, sampling for Impact
Monitoring during Dredging Operations and Water Column Profiling were conducted on 3 and 4 February 2010,
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 |
February’s
sampling: 18 February 2010 |
|
|
b) Routine water quality monitoring |
February’s in situ sampling: 18 February 2010 |
|
Sediment
Sampling and Chemical Analysis |
a) Pit Specific Sediment Chemistry |
December’s
sampling: 3 February 2010 |
|
|
b) Cumulative Impact Sediment Chemistry |
December’s
sampling: 3 February 2010 |
|
Benthic Recolonisation Study |
|
December’s
sampling: 19 January 2010 |
|
Demersal Trawling and Tissue Analysis |
a) Tissue and Whole Body Analyses |
July and August’s sampling: 3 February 2010 |
|
CMP V |
|
|
|
Water Sampling
and Chemical Analysis |
a) Water Column
Profiling |
February’s
sampling: 8 February 2010 |
|
|
b) Impact Monitoring during Dredging
Operations |
February’s
sampling: 8 February 2010 |
1.4
Details
of Outstanding Sampling and / or Analysis
No outstanding sampling remained from February 2010. However, Water Quality Monitoring during Capping which was
scheduled on 5 February 2010 was not conducted as no capping at CMP IV was scheduled
to be carried out on this day.
1.5
Brief
Discussion of the Monitoring Results
Results of Water Column Profiling
and Routine Water Quality Monitoring
for February 2010; Pit Specific Sediment
Chemistry, Cumulative Impact Sediment Chemistry and Benthic Recolonisation for December 2009;
and, Tissue and Whole Body Analyses
for July and August 2009 are presented for CMP IV. Monitoring results presented for CMP V
include Water Column Profiling and Impact Monitoring during Dredging Operations
for February 2010. Detailed results will
be discussed in the relevant Quarterly
Reports.
1.5.1
CMP IV
Water Column Profiling for CMP IV in February
2010
Results of Water Column Profiling
for February 2010 show that levels of Salinity, pH and Dissolved Oxygen (DO)
compiled with WQOs at both Upstream and Downstream
stations (Figures 2 to 4 of Annex B). Levels of Total Suspended Solids (TSS) complied
with WQO at the Upstream station, however, exceedance
of WQO was recorded at the Downstream station (Figure 1 of Annex B). TSS data collected from the Routine Water Quality Monitoring should
be examined further when available from the Contractor
in order to assess any adverse impacts to the marine water quality caused
by the CMP IV operations.
Routine Water Quality Monitoring for CMP IV
during February 2010
In situ Measurements
Levels of pH, DO and Salinity
complied with WQOs at all stations during Routine Water Quality Monitoring in
February 2010 (Figures 5, 8 and 9 of Annex B). All in situ
water quality measurements showed relatively minor variations between
Impact, Intermediate and Reference stations (Figures 5 to 10 of Annex B).
Pit Specific Sediment Chemistry for CMP IV
during December 2009
Concentrations of metals were generally below the Lower Chemical Exceedance
Level (LCEL) at all stations, with the exceptions being Arsenic, Copper, Silver
and Zinc (Figures 11 and 12 of Annex B). Concentrations of Arsenic exceeded LCEL at all Near Pit and Pit Edge stations
(Figure 11 of Annex B). Concentrations of Copper, Silver and Zinc exceeded
LCEL at the Active Pit station NCA
and remained below the criterion at all other stations (Figures 11 and 12 of Annex B). No metal concentrations exceeded the Upper Chemical Exceedance Level (UCEL; Figures 11 and 12 of Annex B).
Concentrations of Total DDT were
higher at the Near Pit station CNA and Active Pit station NCA (Figure 13 of Annex B). Concentrations of 4,4”
DDE, Tributyltin
(TBT) in both interstitial water and sediment samples were higher at the Active
Pit station NCA (Figures 13-15 of Annex B). Concentrations of Low Molecular Weight
(LMW) Polyaromatic Hydrocarbons (PAHs),
High Molecular Weight (HMW) PAHs, Total PAHs and Polychlorinated Biphenyls (PCBs) were
below detection limits at all stations.
Sediment concentrations of Total
Organic Carbon (TOC) were slightly higher at the Active Pit station NCA
relative to other stations (Figure 17 of
Annex B) and all sediment samples were mainly composed
of silt and clay materials (68 – 98 %; Figure
18 of Annex B).
Cumulative Impact Sediment Chemistry for December
2009
Concentrations of all metals,
except Arsenic, were below the LCEL (Figures 19 and 20 of Annex B). Concentrations of Arsenic in sediment samples
from all stations were above the LCEL (Figure 19 of Annex B). Overall, there were only minor differences in
metal concentrations between stations (Figures
19 and 20 of Annex B). All metal
concentrations remained below UCEL (Figures 19 and 20 of Annex B).
The concentration of Total
DDT was higher at Mid Field stations and Near Field station RNA compared to all
other stations (Figure 21 of Annex B).
Concentrations of 4,4” DDE were generally
similar between stations with no obvious spatial trend (Figure 21 of Annex B). Concentrations of TBT in sediment samples were highest at the Far Field
station RFA (Figure 22 of Annex B), whereas TBT concentrations in all interstitial
water samples were below the detection limit. Similarly, concentrations were below detection
limit at all stations for LMW PAHs, HMW PAHs, Total PAHs and PCBs.
Concentrations of TOC in
sediments were relatively similar between stations (Figure 23 of Annex B) and sediments
were mainly composed of silt and clay materials (31.8 – 56.4 %; Figure 24 of Annex B).
Benthic Macro-Infauna
and Taxonomic Identification for CMP IV
A benthic survey was
conducted at the Capped Mud Pit stations and at the Reference stations to the
south of Sha Chau in
December 2009. A total of 179
individuals, belonging to six animal phyla were obtained from the monitoring
stations. Table 1.2 summarises the results of the benthic survey.
Table 1.2 Summary of
Benthic Survey Results during December 2009 Monitoring
|
Area |
Station |
No. of
individuals (Total) |
Biomass (g) (Total) |
Average No.
of Individuals (Per Station) |
Biomass (g)
(Per Station) |
Average
Biomass per individual (mg) |
Average
Number of Genera |
|
Capped Stations |
|
|
|
|
|
|
|
|
CPA |
3 |
9 |
0.08 |
3.00 |
0.03 |
0.01 |
1.67 |
|
CPB |
3 |
16 |
41.57 |
5.30 |
13.96 |
2.60 |
3.67 |
|
CPC |
3 |
14 |
0.22 |
4.67 |
0.07 |
0.02 |
1.67 |
|
(Total) |
|
39 |
41.87 |
- |
14.06 |
- |
- |
|
8.44 |
|
|
|
|
|
|
|
|
RBA |
3 |
42 |
2.37 |
14.00 |
0.79 |
0.06 |
5.67 |
|
RBB |
3 |
66 |
557.16 |
22.00 |
185.72 |
8.44 |
6.00 |
|
RBC |
3 |
41 |
2.14 |
13.67 |
0.71 |
0.05 |
7.00 |
|
(Total) |
|
149 |
561.67 |
- |
187.22 |
- |
- |
|
Total |
18 |
188 |
603.54 |
- |
201.28 |
- |
- |
Total number of individuals,
total biomass, average biomass per individual and
average number of genera were generally lower at the Capped Pit stations than
at the Reference stations.
Biota Tissues/Whole Body Contaminant Analysis
for July and August 2009
Tissue Analysis
Graphical presentation for
the tissue analysis of the demersal trawling samples which
were collected in July and August 2009 is presented in Figures 25 to 38 of Annex B.
Analyses were only conducted on target species in which sufficient tissue
samples were collected. Generally,
tissue concentrations of all metals remained below the relevant Maximum Permitted Concentrations (MPC) which are specified under the Food Adulteration (Metallic Contamination)
Regulations (Cap. 132) of Hong Kong Law, except for Chromium concentrations
in Gastropod tissues sampled at Impact station INA and Reference stations TNB
and TSB (Figure 31).
Overall, concentrations of Inorganic
Arsenic, Cadmium, Chromium, Copper, Lead, Mercury, Nickel, Silver and Zinc
measured in tissues samples of target species were relatively similar between
Impact and Reference stations (Figures 25,
27, 29, 31, 33, 35, 37, 39 and 41). In addition, concentrations of organic contaminants
measured in tissue samples of target species appeared similar between Impact
and Reference stations (Figures 26, 28,
30, 32, 34, 36 and 38). Statistical tests to detect any significant differences
in tissue contaminant concentrations between stations will be presented in the
relevant Quarterly Report.
Whole
Body Analysis
Graphical presentation for
the whole body analysis of demersal trawling samples
which were collected in July and August 2009 is presented in Figures 39 to 48 of Annex B. Analyses were only conducted on the target species
with sufficient whole body samples available.
Concentrations of all metals measured in whole body samples remained
below the relevant MPC standards.
Overall, concentrations of Inorganic
Arsenic, Cadmium, Chromium, Copper, Lead, Mercury, Nickel, Silver and Zinc
measured in whole body samples of target species were relatively similar
between the Impact and Reference stations (Figures
39 to 48). Concentrations of all organic contaminants
measured in whole body samples of all target species also appeared similar
between the Impact and Reference stations (Figure
22, 24, 26, 28 and 30).
1.5.2
CMP V
Water Column Profiling for CMP V during February
2010
Results of Water Column Profiling
for February 2010 show that levels of Salinity, pH and DO compiled with WQOs at both Upstream and Downstream stations (Figures 50 to 52 of Annex B). However, levels of TSS exceeded the WQO at
both Upstream and Downstream stations (Figure 49 of Annex B).
Impact Monitoring during Dredging Operations of
CMP V – February 2010
Impact
Monitoring during Dredging Operations of CMP V was conducted on 3
February 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 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 53 to 56 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
Impact Monitoring during Dredging Operations for CMP V is the only monitoring activity scheduled in the next monthly period of March 2010. The sampling schedule is presented in Annex A.
1.7
Study
Programme
A summary of the Study programme is presented in Annex C.