1.1 Background
1.2 Reporting Period
1.3 Details of Sampling and Laboratory
Testing Activities
1.4 Details of Outstanding Sampling
and/or Analysis
1.5 Brief Discussion of the Monitoring
Results for ESC CMP V
1.6 Activities Scheduled for the Next Month
1.7 Study Programme
Annexes
Annex
A Sampling Schedule
Annex
B Water Quality Monitoring Results
Annex
C Graphical Presentations
Annex
D Study Programme
1.1
Background
1.1.1
The Civil Engineering and Development
Department (CEDD) is managing a number of marine disposal facilities in Hong
Kong waters, including the Contaminated Mud Pits (CMPs) to the South of The
Brothers (SB) and to the East of Sha Chau (ESC) for the disposal of
contaminated sediment, and open-sea disposal grounds located to the South of
Cheung Chau (SCC), East of Tung Lung Chau (ETLC) and East of Ninepins (ENP) for
the disposal of uncontaminated sediment. Two Environmental Permits (EPs),
EP-312/2008/A and EP-427/2011/A, were issued by the Environmental Protection
Department (EPD) to the CEDD, the Permit Holder, on 28 November 2008 and 23
December 2011 for the Dredging, Management and Capping of Contaminated Sediment
Disposal Facilities at ESC CMP V and SB CMPs, respectively.
1.1.2 Under the requirements of the two EPs for ESC CMP V and SB CMPs, EM&A
programmes which encompass water and sediment chemistry, fisheries assessment,
tissue and whole body analysis, sediment toxicity and benthic recolonisation
studies as set out in the EM&A Manuals are required to be implemented.
EM&A programmes have been continuously carried
out during the operation of the CMPs at ESC and SB. A review of the
collection and analysis of such environmental data from the monitoring
programme demonstrated that there had not been any adverse environmental
impacts resulting from disposal activities ([1])([2]) . The current programme will assess the impacts resulting
from dredging, disposal and capping operations of CMP V as well as capping
operations of SB CMPs.
1.1.3
The present EM&A programme under Agreement No. CE 63/2016 (EP)
covers the dredging, disposal and capping operations of the ESC CMP V as well as the capping operations of the SB
CMPs (see Annex A for the EM&A programme). The scheduled EM&A programme for SB CMPs was
completed in December 2018. Detailed works schedule for ESC CMP V is shown in Figure 1.1. In January 2020, the
following works were undertaken:
· Disposal of
contaminated mud at ESC CMP Vd up to 15 January 2020;
· Disposal of
contaminated mud at ESC CMP Vb since 16 January 2020; and
· Capping operations
at ESC CMP Vd since 16 January 2020.
Figure
1.1 Works Schedule for ESC CMP V
1.2
Reporting Period
1.2.1
This Monthly
EM&A Report for January 2020 covers the EM&A activities for the reporting
month of January 2020.
1.3
Details of Sampling
and Laboratory Testing Activities
1.3.1
The following monitoring activities were
undertaken for ESC CMP V in January 2020:
· Water Column
Profiling of ESC CMP Vd;
· Routine
Water Quality Monitoring of ESC CMPs;
· Pit Specific
Sediment Chemistry of ESC CMP Vd; and
· Demersal
Trawling for ESC CMPs.
1.4
Details of Outstanding
Sampling and/or Analysis
1.4.1
No outstanding sampling remained
for January 2020.
1.4.2
The following analyses are in progress
and will be presented in the corresponding quarterly report:
· Species
identification of the biota samples collected from Demersal Trawling for ESC
CMPs
in January 2020.
1.5
Brief Discussion of the
Monitoring Results for ESC CMP V
1.5.1
Brief discussion of the monitoring results of the following
activities for ESC CMP V is presented in this Monthly
EM&A Report for January 2020:
· Water Column
Profiling of ESC CMP Vd in January 2020;
· Routine
Water Quality Monitoring of ESC CMPs in January
2020; and
· Pit Specific
Sediment Chemistry of ESC CMP Vd in January
2020.
1.5.2
Water
Column Profiling of ESC CMP Vd – January 2020
1.5.3
Water Column Profiling was undertaken at a total of two sampling stations
(Upstream and Downstream stations) on 7 January 2020. The monitoring
results have been assessed for compliance
with the Water Quality Objectives (WQOs) set by Environmental
Protection Department (EPD). This consists of a review of the EPD routine water
quality monitoring data for the dry season period (November to March) of 2009 - 2018 from
stations in the Northwestern Water Control Zone (WCZ), where the ESC CMPs are
located ([3]). . For Salinity,
the averaged value obtained from the Reference (Upstream) station
was used for the basis as the WQO. Levels of
Dissolved Oxygen (DO) and Turbidity were also assessed for compliance with the
Action and Limit Levels (see Table B1 of Annex B for details).
In-situ Measurements
1.5.4
Analyses of results for January 2020
indicated that levels of Salinity,
pH and DO complied with the WQOs at both
Downstream and Upstream stations (Table B2 of Annex B). Levels of DO and Turbidity at all stations complied with the
Action and Limit Levels (Tables B1 and B2 of Annex B).
Laboratory
Measurements for Suspended Solids (SS)
1.5.5
Analyses of results January 2020 indicated
that the SS levels at both Downstream and Upstream stations complied with the
WQO and the Action and Limit Levels (Tables B1 and B2 of Annex B).
1.5.6
Overall, the monitoring results indicated
that the mud disposal operation at ESC CMP Vd did not appear to cause any
deterioration in water quality during this reporting period.
1.5.7
Routine
Water Quality Monitoring of ESC CMPs – January 2020
1.5.8
Routine Water Quality Monitoring of ESC CMPs was undertaken on 8 January 2020. The monitoring
results have been assessed for compliance
with the WQOs (see Section 1.5.3 for details). The monitoring results are shown in Tables
B3 and B4 of Annex B and Figures
1 - 10 of Annex C. A total of sixteen
(16) monitoring stations were sampled in January 2020 as shown in Figure 1.2.
In-situ
Measurements
1.5.9
Graphical presentation of the monitoring
results (Temperature, DO, pH, Salinity and Turbidity) is shown in Figures 1 - 6 of Annex C. Analyses of
results for January 2020 indicated that the levels of pH, Salinity and DO complied
with the WQOs at all stations in January
2020.
1.5.10
The levels of DO and Turbidity complied
with the Action and Limit Levels at all stations (Table
B3 of Annex B; Figures 3 and 6 of Annex C).
1.5.11
Overall, in-situ measurement results of the Routine
Water Quality Monitoring indicated
that the disposal operation at ESC CMP Vd did not appear to cause any
unacceptable impacts in water quality in January 2020.
Laboratory Measurements
1.5.12
Laboratory analysis of January 2020
results indicated that concentrations of Arsenic, Chromium, Copper, Lead,
Nickel and Zinc were detected in January 2020 samples
at most stations and the concentrations of these metals and metalloids were similar amongst the stations, except the concentrations of Copper
and Zinc were higher at Reference stations (Table
B4 of Annex B; Figure 7 of Annex C).
1.5.13
For nutrients, concentrations of Total
Inorganic Nitrogen (TIN) at all stations were higher than the WQO (0.5 mg/L) (Table B4 of Annex B; Figure 8 of Annex C). It
should be noted that due to the effect of the Pearl River, the North Western
WCZ has historically experienced higher levels of TIN ([4]). .
Therefore, the exceedances of TIN WQO at these stations are unlikely to be
caused by the disposal operation at ESC CMP Vd. The concentrations of Ammonia
Nitrogen (NH3-N) and 5-day Biochemical Oxygen Demand (BOD5)
were generally similar amongst the stations in January 2020 (Table
B4 of Annex B; Figure 8 and 9 of Annex C).
1.5.14
Analyses of results for January 2020 indicated that the SS levels at all stations were lower than the WQO (13.6 mg/L for dry season) and complied with the Action and Limit Levels (Tables B1 and B4 of Annex B; Figure 10 of Annex C).
1.5.15
Overall, results of the Routine Water
Quality Monitoring indicated that the disposal operation at ESC CMP Vd did not
appear to cause any unacceptable deterioration in water quality in January 2020.
Detailed statistical analysis will be presented in the Quarterly Report to
investigate any spatial and temporal trends of potential concern.
1.5.16
Pit
Specific Sediment Chemistry of ESC CMP Vd – January 2020
1.5.17
Monitoring locations for Pit Specific Sediment Chemistry for ESC CMP Vd are shown in Figure 1.3. A total of six (6) monitoring stations were sampled
on 3 January 2020.
1.5.18
The concentrations of most inorganic
contaminants were lower than the Lower Chemical Exceedance Levels (LCELs) at most
stations, except for Arsenic, Copper, Silver and
Zinc (Figures 11 and 12 of Annex C). The concentrations of Arsenic were higher than the LCEL at Pit-Edge station ESC-NEAA. The concentrations of Copper were higher than the Upper Chemical Exceedance Level (UCEL) at Active-Pit station ESC-NPAA. The concentrations of
Silver and Zinc were higher than the LCELs at Active-Pit station ESC-NPAA.
1.5.19
For organic contaminants, the concentrations
of Total Organic Carbon (TOC) were higher at Active-Pit stations in January 2020 (Figure 13 of Annex C). The concentrations of Tributyltin (TBT) were generally below the limit of reporting across most
stations, except at
Active-Pit station ESC-NPAA in January 2020 (Figure
14 of Annex C). Total Polychlorinated Biphenyls (PCBs), Total
dichloro-diphenyl-trichloroethane (DDT) and 4,4’-dichlorodiphenyldichloroethylene
(DDE) concentrations were below the limit of reporting at all stations. The
concentrations of Low Molecular Weight and High Molecular Weight Polycyclic
Aromatic Hydrocarbons (PAHs) were generally below LCELs at most stations, except at Active-Pit Station ESC-NPAA. The concentrations of
Low Molecular Weight and High Molecular Weight PAHs were higher than LCEL and
UCEL respectively at Active-Pit Stations ESC-NPAA (Figure
15 of Annex C).
1.5.20 Whilst the average concentration of
Arsenic in the Earth’s crust is generally ~2mg/kg, significantly higher Arsenic
concentrations (median = 14 mg/kg) have been recorded in Hong Kong’s onshore
sediments ([5]). It is presumed that the natural concentrations of
Arsenic are similar in onshore and offshore sediments ([6]), and relatively high Arsenic levels may thus occur
throughout Hong Kong. Therefore, the LECL exceedances of Arsenic are unlikely
to be caused by the disposal operations at ESC CMP Vd but rather as a result of
naturally occurring deposits.
1.5.21
Considering that the higher levels of Copper, Silver, Zinc, Low
Molecular Weight and High Molecular Weight PAHs occurred within one Active-Pit
station only but not at the Pit-Edge and Near-Pit stations, there is no
evidence indicating any unacceptable environmental impacts to sediment quality
as a result of the contaminated mud disposal operations at ESC CMP Vd in January
2020. Statistical
analysis will be undertaken and presented in the corresponding quarterly report
to investigate whether there are any unacceptable impacts in the area caused by
the contaminated mud disposal.
1.6
Activities Scheduled
for the Next Month
1.6.1
The following monitoring activities will be conducted in the next monthly
period of February 2020 for ESC CMP V (see Annex A for the sampling schedule ([7]):
· Water Column
Profiling of ESC CMP Vb;
· Routine Water
Quality Monitoring of ESC CMPs;A
· Pit Specific
Sediment Chemistry of ESC CMP Vb;
· Cumulative
Impact Sediment Chemistry of ESC CMPs;
· Sediment
Toxicity Tests of ESC CMPs;
· Demersal
Trawling for ESC CMPs; and
· Water Quality
Monitoring During Capping of ESC CMPs.
1.7
Study Programme
1.7.1
A summary of the Study Programme is
presented in Annex D.
