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 April 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 April 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 April 2018 covers
the EM&A activities for the reporting month of April
2018.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following monitoring
activities were undertaken for ESC CMP V in April
2018:
·
Water Column Profiling of ESC CMP Vd;
·
Routine Water Quality Monitoring 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 April 2018.
1.4
Details
of Outstanding Sampling and/or Analysis
1.4.1
No outstanding sampling remained
for April 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 April 2018:
·
Water Column Profiling of ESC CMP Vd in April 2018;
·
Routine Water Quality Monitoring of ESC CMP Vd in April 2018; and
·
Pit Specific Sediment Chemistry of ESC CMP Vd in April 2018.
1.5.2
Water Column Profiling of ESC CMP Vd – April 2018
1.5.3
Water Column
Profiling was undertaken at
a total of two sampling stations (Upstream and Downstream stations) on 10 April
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 April 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 April 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
Routine Water Quality Monitoring of ESC CMP V – April 2018
1.5.8
Routine Water
Quality Monitoring of ESC CMP V was
undertaken on 11 April 2018. 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 April
2018 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 April 2018 indicated that the levels of pH, Salinity and DO complied with
the WQOs at all stations (Impact, Intermediate, Reference and Ma Wan stations)
in April 2018, except slightly highter
Salinity was recorded at Ma Wan station (Table B3 of Annex B;
Figures 1, 3 and 5 of Annex C). Ma Wan station is located further away
from other monitoring stations located closer to the ESC CMP Vd where levels of
Salinity complied with WQO requirements.
It is thus considered that higher levels of Salinity recorded in Ma Wan
station was not related to the disposal operation at ESC CMP Vd.
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
operation at ESC CMP Vd did not appear to cause any unacceptable impacts in water quality in April 2018.
Laboratory
Measurements
1.5.12
Laboratory
analysis of April 2018 results indicated that concentrations of Cadmium, Silver
and Mercury were below their limit of reporting at all stations. Arsenic, Chromium, Nickel, Lead, Copper and Zinc were
detected in April 2018 samples at most stations and the concentrations of these metals and metalloids were similar amongst most stations, except
much lower Chromium was detected at Reference station (Table B4 of Annex B; Figure 7 of Annex C).
1.5.13
For nutrients,
concentrations of Total Inorganic Nitrogen (TIN) at all stations in April 2018 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 CMP
Vd. Concentrations of Ammonia
Nitrogen (NH3-N) and 5-day Biochemical Oxygen Demand (BOD5) were similar
amongst all stations in April 2018 (Table B4 of Annex B; Figure 8 and 9 of Annex C).
1.5.14
Analyses of
results for April 2018 indicated
that the SS levels at
all stations were lower than the WQO (10.8 mg/L for wet season) and SS levels compiled with the Action and Limit Levels at all
stations (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
operation at ESC CMP Vd did not appear to cause any unacceptable deterioration
in water quality in April 2018.
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 Vd – April 2018
1.5.17
Monitoring
locations for Pit Specific Sediment Chemistry
for ESC CMP Vd are shown in Figure 1.3.
A total of six (6) monitoring stations were sampled in April 2018.
1.5.18
The
concentrations of all inorganic contaminants were lower than the Lower Chemical
Exceedance Level (LCEL) at all stations
in April 2018
(Figures 11, 12 of Annex C).
1.5.19
For organic
contaminants, the concentrations of Total Organic Carbon (TOC) were generally
similar in April 2018 (Figures 13 of
Annex C). The concentration of Tributyltin (TBT) was generally higher at Active-Pit station
ESC-NPAA in April 2018 (Figure 14 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 April 2018.
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 Vd
in April 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 May 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.