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 March 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 March 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 March 2018 covers the EM&A
activities for the reporting month of March 2018.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following
monitoring activities were undertaken for ESC CMP V in March 2018:
·
Water Column Profiling of ESC CMP Vd; and
·
Pit Specific Sediment Chemistry of ESC CMP Vd.
1.3.2
No monitoring
activities were undertaken for SB CMP in March 2018.
1.4
Details of Outstanding Sampling and/or Analysis
1.4.1
No outstanding sampling remained for March 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 March 2018:
·
Water Column Profiling of ESC CMP Vd in March 2018;
·
Pit Specific Sediment Chemistry of ESC CMP Vd in February and March 2018; and
·
Cumulative Impact Sediment Chemistry for ESC CMP V in February 2018.
1.5.2
Water
Column Profiling of ESC CMP Vd – March 2018
1.5.3
Water Column
Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 6 March 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
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 March
2018 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 March
2018 indicated that the SS levels complied with the WQO and
the Action and Limit Levels at both Upstream and Downstream stations (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 – February and March 2018
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 February and March 2018.
1.5.9 The
concentrations of all inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at most stations
in February and March 2018,
except the exceedance of LCEL for Arsenic at Active Pit station ESC-NPAB in
March 2018 (Figures 1, 2, 5 and 6 of Annex C).
1.5.10 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 ([4]).
It is presumed that the natural concentrations of Arsenic are similar in
onshore and offshore sediments ([5]), 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.
1.5.11 For
organic contaminants, the concentrations of Total Organic Carbon (TOC) were
generally similar in February and March 2018 (Figures
3 and
7 of
Annex C).
The concentration of Tributyltin
(TBT) was generally higher at Active-Pit
stations ESC-NPAB and ESC-NPAA in February and March 2018, respectively (Figure
4 and
8 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 February and March 2018.
1.5.12 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 February and March 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.
1.5.13
Cumulative Impact
Sediment Chemistry of ESC CMP V – February 2018
1.5.14
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 February 2018.
1.5.15
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 February
2018, except Arsenic exceeded the LCEL at Mid Field
stations ESC-RMA and ESC-RMB as well as the Far Field stations ESC-RFA and
ESC-RFB (Figures 9 and 10
of Annex C).
1.5.16
As discussed in Section 1.5.10, the natural
concentrations of Arsenic are relatively high in 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.
1.5.17
For organic contaminants,
the concentrations of TOC were generally similar in February 2018 with lower
concentrations recorded at Capped Pit stations ESC-RCA and ESC-RCB (Figure 11 of Annex C). The concentrations of TBT were
recorded to be higher at Ma Wan station (Figure
12 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
13 of Annex C).
1.5.18
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 February 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 April 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; and
·
Pit Specific Sediment Chemistry of ESC CMP Vd.