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 DECember 2017
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 December 2017,
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 December 2017 covers the EM&A
activities for the reporting month of December 2017.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following
monitoring activities were undertaken for ESC CMP V in December 2017:
·
Pit Specific Sediment Chemistry of ESC CMP Vd was
undertaken on 5 December 2017;
·
Cumulative
Impact Sediment Chemistry of ESC CMP V was undertaken
on 5 and 6 December 2017
·
Water Column Profiling of ESC CMP Vd was
undertaken on 7 December 2017; and
1.3.2
The following monitoring activities were
undertaken for SB CMP in December 2017:
· Benthic Recolonisation Studies of SB CMPs
was undertaken on 4 December 2017.
1.4
Details
of Outstanding Sampling and/or Analysis
1.4.1
No outstanding sampling and
analysis remained for December 2017.
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 December 2017:
·
Water Column Profiling of ESC CMP Vd in December 2017;
·
Pit Specific
Sediment Chemistry of ESC CMP Vd in December 2017; and
·
Cumulative Impact Sediment
Chemistry of ESC CMP V in
December 2017.
1.5.2
Water Column Profiling of ESC CMP Vd – December
2017
1.5.3
Water Column Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 7 December 2017. 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 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 December 2017 indicated that levels of DO, Salinity and pH complied with the WQOs at both
Downstream and Upstream stations (Table B2 of Annex B).
In
addition, 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 December
2017 indicated that the SS levels
were higher than the WQO at Downstream station. However, both Upstream and Downstream
stations 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 Vd did not appear to cause any deterioration in water
quality during this reporting period.
1.5.7
Pit Specific Sediment Chemistry of ESC CMP Vd – December 2017
1.5.8
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 in December 2017.
1.5.9
The
concentrations of all inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all
stations in December 2017 (Figures 1 and 2 of Annex C).
1.5.10
For organic
contaminants, the concentrations of Total Organic Carbon (TOC) were generally similar
in December 2017 with higher concentration of TOC detected at Active-Pit station ESC-NPAA (Figure 3 of Annex C). The concentrations
of Tributyltin (TBT) were higher at Near-Pit station ESC-NNAA in December 2017 (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 all stations in December 2017.
1.5.11
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 December 2017.
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.
1.5.12
Cumulative Impact Sediment Chemistry of ESC CMP V
– December
2017
1.5.13
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 in December 2017.
1.5.14
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 December 2017, except Arsenic exceeded the LCEL at Mid Field stations
ESC-RMA and ESC-RMB as well as Far Field station ESC-RFB (Figures 5 and 6 of Annex C).
1.5.15
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 (1). It is presumed that the natural concentrations of Arsenic are similar in
onshore and offshore sediments (2), and relatively high Arsenic levels may thus occur
throughout Hong Kong. Therefore, the LCEL 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.
1.5.16
For organic contaminants, the concentrations
of TOC were generally similar in December 2017 with lower concentrations
recorded at Capped Pit stations ESC-RCA and ESC-RCB (Figure 7 of Annex C). The
concentrations of TBT were recorded to be higher at Ma Wan station (Figure 8 of Annex C). High Molecular Weight PAHs was detected at Capped Pit station
ESC-RCA (Figure 9 of Annex C). Low Molecular Weight PAHs, PCBs, DDT and
DDE concentrations were recorded below the limit of
reporting at all stations.
1.5.17
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 December 2017. 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 January 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 CMP V;
·
Pit Specific Sediment Chemistry of ESC CMP Vd; and
·
Demersal Trawling for ESC CMP V