Agreement No. CE 63/2016 (EP)
Environmental Monitoring and Audit
for Disposal Facility to the East of Sha Chau (2017-2020) - Investigation
MONTHLY EM&A REPORT FOR September 2018
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). Detailed works schedule for ESC CMP V and
SB CMPs is shown in Figure
1.1. In September 2018, the following work
was being undertaken:
· Disposal of contaminated mud at ESC CMP Vd.
Figure 1.1 Works Schedule
for ESC CMP
V and SB CMPs
1.2
Reporting Period
1.2.1
This Monthly
EM&A Report for
September
2018 covers the
EM&A activities for the reporting month of September 2018.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following monitoring
activities were undertaken for ESC CMP V in September 2018:
·
Water Column Profiling of ESC CMP Vd;
·
Pit Specific Sediment Chemistry of ESC CMP Vd; and
·
Sediment Chemistry after a Major Storm of ESC CMP V.
1.3.2
No monitoring activities were
scheduled to be undertaken for SB CMP in September 2018.
1.4
Details of Outstanding
Sampling and/or Analysis
1.4.1
No outstanding sampling remained for September 2018.
1.4.2
The following laboratory analyses were still in
progress during the preparation of this monthly report and hence is not
presented in this monthly report:
·
Laboratory
analyses of sediment samples collected for Pit
Specific Sediment Chemistry of ESC CMP Vd in September 2018; and
·
Laboratory
analyses of sediment samples collected for Sediment
Chemistry after a Major Storm of ESC CMP V in September 2018.
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 September 2018:
·
Water Column Profiling of ESC CMP Vd in September 2018;
·
Pit Specific Sediment Chemistry of ESC CMP Vd in August 2018; and
·
Cumulative
Impact Sediment Chemistry of ESC CMP V in August 2018.
1.5.2
Water Column
Profiling of ESC CMP Vd – September 2018
1.5.3
Water Column
Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 7 September 2018. 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 2007 - 2016
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 September 2018 indicated that levels of Salinity and pH complied with the WQOs at both
Downstream and Upstream stations while levels of DO were lower than the WQO (Table
B2 of Annex
B). Levels of DO and Turbidity
at all stations complied with the Action and Limit Levels ([4])
(Tables B1 and B2 of Annex B).
Laboratory Measurements for
Suspended Solids (SS)
1.5.5
Analyses of
results for September 2018 indicated that the SS levels complied with the WQO and the
Action and Limit Level at both Downstream and Upstream stations (Tables
B1 and B2 of Annex
B).
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.
1.5.6
Pit Specific
Sediment Chemistry of ESC CMP Vd – August
2018
1.5.7
Monitoring
locations for Pit Specific Sediment Chemistry for ESC CMP Vd are shown in Figure 1.2. A total of six (6) monitoring stations
were sampled on 13 August 2018.
1.5.8
The concentrations of all inorganic contaminants were lower
than the Lower Chemical Exceedance Level (LCEL) at all stations
in August 2018 (Figures 1 and 2
of Annex C).
1.5.9
For organic
contaminants, the concentrations of Total Organic Carbon (TOC) were generally
similar in August 2018, except higher concentrations of TOC were recorded at
the Active-Pit station ESC-NPAA (Figure
3 of Annex C). The
concentration of Tributyltin (TBT) was generally
similar amongst stations in August 2018 (Figure 4 of Annex C). Low and High Molecular Weight Polycyclic
Aromatic Hydrocarbons (PAHs), Total Polychlorinated Biphenyls (PCBs), Total
dichloro-diphenyl-trichloroethane (DDT) and 4,4’-dichlorodiphenyldichloroethylene
(DDE) concentrations were below the limit of reporting at most stations in
August 2018, except High Molecular Weight PAHs were detected at Active-Pit station
ESC-NPAB and Pit-Edge station ESC-NEAB (Figure 5 of Annex
C).
1.5.10
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 Vd in August
2018. 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.
1.5.11
Cumulative Impact
Sediment Chemistry of ESC CMP V – August 2018
1.5.12
Monitoring locations
for Cumulative Impact Sediment Chemistry for ESC CMP V are shown in Figure
1.3. A total of nine (9) monitoring stations
were sampled on 21 and 22 August
2018.
1.5.13
Analyses of results for
the Cumulative Impact Sediment Chemistry Monitoring
indicated that the concentrations of most inorganic
contaminants were below the LCEL at all stations in
August 2018, except concentrations of Arsenic were
higher than the LCEL at Mid-field stations ESC-RMA and ESC-RMB (Figures 6 and 7
of Annex C). 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.
1.5.14
For organic
contaminants, the concentrations of TOC were varied between stations in August
2018, with the generally lower concentrations of TOC recorded at Capped-Pit
stations ESC-RCA and RSC-RCB (Figure
8 of Annex C). The concentrations of TBT recorded were generally similar amongst stations except higher
concentrations of TBT were recorded at Ma Wan station (Figure 9 of Annex C). Low and High Molecular Weight PAHs, PCBs, DDT and DDE concentrations were
generally recorded below the limit of reporting at all stations, except concentrations
of High Molecular Weight PAHs was higher than the limit of reporting at Capped
Pit station ESC-RCA (Figure
10 of Annex C).
1.5.15
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 Vd
in August 2018. 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 October 2018 for ESC CMP V (see Annex A
for the sampling schedule):
·
Water Column Profiling of ESC CMP Vd;
·
Routine Water Quality Monitoring of ESC CMPs; and
·
Pit Specific Sediment Chemistry of ESC CMP Vd.