Contents
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 May 2020, the following works were undertaken:
· Disposal of contaminated mud at ESC CMP Vb; and
· Capping operations at ESC CMP Vd.
Figure 1.1 Works Schedule for ESC CMP V
1.2
Reporting Period
1.2.1
This Monthly
EM&A Report for
May 2020 covers the EM&A
activities for the reporting month of May 2020.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following monitoring activities
were undertaken for ESC CMP V in May 2020:
· Water Column Profiling of ESC CMP Vb;
· Routine Water Quality Monitoring of ESC CMPs; and
· Pit Specific Sediment Chemistry of ESC CMP Vb.
1.4
Details of Outstanding
Sampling and/or Analysis
1.4.1
No outstanding sampling remained
for May 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 May 2020:
· Water Column Profiling of ESC CMP Vb;
· Routine Water Quality Monitoring of ESC CMPs; and
· Pit Specific Sediment Chemistry of ESC CMP Vb.
1.5.2 Water Column Profiling of ESC CMP Vb – May
2020
1.5.3
Water Column Profiling was undertaken at a total of two sampling stations
(Upstream and Downstream stations) on 7 May 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
wet season period (April to October) 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 May 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 May 2020 indicated that the SS
levels at both Downstream and Upstream stations were
higher than the WQO, but both complied with 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 Vb did not appear to
cause any deterioration in water quality during this reporting period.
1.5.7 Routine Water Quality Monitoring of ESC CMPs – May 2020
1.5.8 Routine Water Quality Monitoring of ESC CMPs was undertaken on 6 May 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 May 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 May 2020 indicated that the levels of pH, Salinity and DO complied
with the WQOs at all stations in May 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). There is no
evidence indicating any unacceptable environmental impacts to nearby water
sensitive receivers as a result of the mud disposal operations at ESC CMPs in May 2020.
Laboratory Measurements
1.5.11 Laboratory analysis of May 2020 results indicated that
concentrations of Arsenic, Cadmium, Chromium, Copper, Mercury, Lead, Nickel and
Zinc were detected in May 2020 samples at most stations and the concentrations
of these metals and metalloids were similar amongst the stations, except the
concentrations of Copper were higher at Reference stations, and the
concentrations of Zinc was lower at Ma Wan Station (Table
B4 of Annex B; Figure 7 of Annex C).
1.5.12 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 CMPs. The concentrations of
Ammonia Nitrogen (NH3-N) and 5-day Biochemical Oxygen Demand (BOD5)
were similar across the stations in May 2020 (Table
B4 of Annex B; Figure 8 and 9 of Annex C).
1.5.13 Analyses of results for May 2020 indicated that the SS
levels at Ma Wan station complied with the WQO, and the SS levels at all
stations complied with the Action and Limit Levels (Tables B1 and B4 of Annex B; Figure 10 of Annex C). There is no evidence indicating any unacceptable
environmental impacts to nearby water sensitive receivers as a result of the
mud disposal operations at ESC CMPs in May 2020.
1.5.14 Overall, results of the Routine Water Quality
Monitoring indicated that the disposal operation at ESC CMPs did not appear to
cause any unacceptable deterioration in water quality in May 2020.
Detailed statistical analysis will be presented in the Quarterly Report to
investigate any spatial and temporal trends of potential concern.
1.5.15 Pit Specific Sediment Chemistry of ESC CMP Vb
– May 2020
1.5.16 Monitoring locations for Pit
Specific Sediment Chemistry for ESC CMP Vb are shown in Figure 1.3. A total of six (6) monitoring stations were
sampled on 5 May 2020.
1.5.17 The concentrations of most inorganic contaminants were lower
than the Lower Chemical Exceedance Levels (LCELs) at most stations, except for Arsenic (Figures 11 and 12 of Annex C).
The concentrations of Arsenic were higher than the LCEL at Pit-Edge stations ESC-NECA & ESC-NECB.
1.5.18 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 Vb but rather as a result of naturally occurring deposits.
1.5.19 For organic contaminants, the concentrations
of Total Organic Carbon (TOC) were higher at Active-Pit station ESC-NPCB in May 2020
(Figure 13 of Annex C).
The concentrations of Low Molecular Weight and High Molecular Weight
Polycyclic Aromatic Hydrocarbons (PAHs) were lower than the
LCELs at all stations (Figure
14 of Annex C). The concentrations of Total Polychlorinated Biphenyls
(PCBs), Tributyltin (TBT),
Total dichloro-diphenyl-trichloroethane
(DDT) and 4,4’-dichlorodiphenyldichloroethylene (DDE) were below the limit of
reporting at all stations in May 2020.
1.5.20
Overall,
there is no evidence indicating any unacceptable environmental impacts to
sediment quality as a result of the contaminated mud disposal operations at ESC
CMP Vb in May 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 June 2020 for ESC CMP V (see Annex A for the sampling schedule ([7])):
· Water Column Profiling of ESC CMP Vb;
· Pit Specific Sediment Chemistry of ESC CMP Vb;
· Cumulative Impact Sediment Chemistry of 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.
([1]) ERM (2013) Final Report. Submitted under Agreement No. CE 4/2009 (EP) Environmental Monitoring and Audit for Contaminated Mud Pit at East Sha Chau. For CEDD.
([2]) ERM (2017) Final Report. Submitted under Agreement No. CE 23/2012 (EP) Environmental Monitoring and Audit for Contaminated Mud Pits to the South of The Brothers and at East Sha Chau (2012 - 2017). For CEDD.
([5]) Sewell RJ (1999) Geochemical Atlas of Hong Kong. Geotechnical Engineering Office, Government of the Hong Kong Special Administrative Region