Contents
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
Annexes
Annex A Sampling Schedule
Annex B Water Quality Monitoring Results
Annex C Graphical Presentations
Annex D Study Programme
Environmental Monitoring and Audit
for Disposal Facility to the East of Sha Chau
(2017-2020) - Investigation
MONTHLY EM&A REPORT FOR February 2021
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
A proposal on the change of number of
sample replication of water quality & sediment monitoring and combination
of routine water quality monitoring and water quality monitoring during capping
operation was submitted to EPD and agreed by EPD on 3 December 2020. The
proposed changes have been effective for the EM&A
activities since December 2020. The latest sampling schedule is provided
in Annex A.
1.1.4
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 February 2021, 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 February 2021 covers the EM&A
activities for the reporting month of February 2021.
1.3
Details of Sampling and Laboratory Testing Activities
1.3.1
The following
monitoring activities were undertaken for ESC CMP V in February 2021:
· Water Column Profiling of ESC CMP Vb;
· Routine Water Quality Monitoring of ESC CMPs;
· Pit Specific Sediment Chemistry of ESC CMP Vb;
· Cumulative Impact Sediment Chemistry of ESC CMPs;
· Sediment Toxicity Tests of ESC CMPs; and
· Demersal Trawling for ESC CMPs.
1.4
Details of Outstanding Sampling and/or Analysis
1.4.1
No outstanding sampling remained for February
2021.
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 February 2021; and
· Sediment Toxicity Tests of ESC CMPs in February 2021.
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 February 2021:
· Water Column Profiling of ESC CMP Vb;
· Routine Water Quality Monitoring of ESC CMPs;
· Pit Specific Sediment Chemistry of ESC CMP Vb; and
· Cumulative Impact Sediment Chemistry of ESC CMPs.
1.5.2
Water Column Profiling of ESC CMP Vb – February 2021
1.5.3
Water Column Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 11 February 2021.
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 2010 - 2019 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 February 2021 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 for February 2021 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 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 – February 2021
1.5.8
Routine Water Quality Monitoring of ESC CMPs was undertaken on 4 February 2021. 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
ten (10) monitoring stations were sampled in February 2021 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 indicated that
the levels of pH, Salinity and DO complied with the WQOs at all stations in
February 2021.
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 and
capping operation at ESC CMPs did not appear to cause any unacceptable impacts
in water quality in February 2021.
Laboratory Measurements
1.5.12
Laboratory
analysis of February 2021 results indicated that concentrations of Arsenic,
Chromium, Copper, Lead, Nickel and Zinc were detected in February 2021 samples
at all stations and their concentrations were generally similar across stations
(Table B4 of Annex B; Figure 7 of Annex C).
1.5.13
For nutrients,
concentrations of Total Inorganic Nitrogen (TIN) at Ma Wan station complied
with the WQO (0.5 mg/L) while those recorded at Reference, Intermediate and
Impact stations were higher than the WQO (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) were generally
similar across stations in February 2021 (Table B4 of Annex B; Figure 8 of Annex C). The concentrations of
Biochemical Oxygen Demand (BOD5) were generally similar across stations (Table B4 of Annex B; Figure 9 of Annex C).
1.5.14
Analyses of
results for February 2021 indicated that the SS levels at all stations complied
with the WQO (12.8 mg/L) and 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 and capping operation at ESC CMPs did not
appear to cause any unacceptable deterioration in water quality in February
2021. 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 Vb – February 2021
1.5.17
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 8 February 2021.
1.5.18
The concentrations of most inorganic contaminants were lower than the Lower Chemical Exceedance
Levels (LCELs) at most stations, except for Arsenic and Copper (Figures
11 and 12 of Annex C). The
concentrations of Arsenic were higher than the LCEL at Near-Pit station ESC-NNCA,
Pit-Edge stations ESC-NECA and ESC-NECB; the concentrations of Copper was
higher than LECL at Active-Pit station ESC-NPCB.
1.5.19
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.
1.5.20
Considering that
the higher levels of Copper occurred within 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 Vb in
February 2021.
1.5.21
For organic
contaminants, the concentrations of Total Organic Carbon (TOC) were higher at
Pit-Edge station ESC-NPCB
in February 2021 (Figure 13 of Annex C). The concentrations of Low Molecular Weight and High
Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs) were lower than the LECLs at all stations (Figure 14 of Annex C).
The concentrations of Tributyltin (TBT) were higher at Near-Pit station ESC-NNCA and
Active-Pit station ESC-NPCA (Figure 15 of Annex C). The concentrations of Total Polychlorinated
Biphenyls (PCBs), Total dichloro-diphenyl-trichloroethane (DDT) and 4,4’-dichlorodiphenyldichloroethylene
(DDE) were below the limit of reporting at all stations in February 2021.
1.5.22
Overall, there is no evidence indicating
any unacceptable environmental impacts to sediment quality outside the pit area
as a result of the contaminated mud disposal operations at ESC CMP Vb in February 2021.
1.5.23
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.
1.5.24
Cumulative Impact Sediment Chemistry
of ESC CMPs – February 2021
1.5.25
Monitoring
locations for Cumulative Impact Sediment Chemistry for ESC CMPs are shown in Figure
1.4. A total of nine (9) monitoring stations were sampled on 9 and
10 February 2021.
1.5.26
Analyses of
results for the Cumulative
Impact Sediment Chemistry Monitoring indicated that the concentrations of most inorganic
contaminants were below the LCEL at most stations in February 2021, except concentrations of Arsenic were higher than the
LCEL at Mid-field stations ESC-RMA, ESC-RMB, Near-field station ESC-RNB1,
Capped Pit stations ESC-RCA1 and ESC-RCB1 (Figures 16 and 17 of Annex C). As discussed in Section 1.5.19, 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.
1.5.27
For organic contaminants, the concentrations of TOC were higher at
Far-field station ESC-RFA (Figure 18 of Annex C). The concentrations of TBT
were higher at Ma Wan station (Figure 19 of Annex C). The concentrations of High
Molecular Weight PAHs were below LECL (Figure 20 of Annex C). The concentrations of Total PCBs, Total DDT, 4,4’- DDE and Low Molecular Weight PAHs were below the limit of reporting at all stations in
February 2021.
1.5.28
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
February 2021. 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 March 2021 for ESC CMP V (see Annex A for the sampling schedule):
· Water Column Profiling of ESC CMP Vb;
· Routine Water Quality Monitoring of ESC CMPs; and
· Pit Specific Sediment Chemistry of ESC CMP Vb.
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.