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 May 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])([3])([4])([5]). 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 May 2017,
the following works were 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 May 2017 covers the EM&A activities for the reporting month of May 2017.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following
monitoring activities were undertaken for ESC CMP V in May 2017:
·
Water Column Profiling of ESC CMP Vd was
undertaken on 16 May 2017;
·
Pit Specific Sediment Chemistry of ESC CMP Vd was undertaken
on 17 May 2017; and
·
Routine Water Quality Monitoring of ESC CMP V was undertaken on 18 May 2017.
1.3.2
The following
monitoring activity was undertaken for SB CMP 2 in May 2017:
·
Water Quality Monitoring During
Capping of SB CMPs was
undertaken on 31 May 2017.
1.4
Details of Outstanding
Sampling and/or Analysis
1.4.1
No outstanding sampling remained
for May 2017.
1.4.2
The following laboratory analyses are in
progress during the preparation of this monthly report and will be presented in
the next monthly report once the data are available:
· Laboratory analyses of
sediment samples collected for Pit Specific
Sediment Chemistry of ESC CMP Vd in May 2017.
1.5
Brief Discussion of the
Monitoring Results for ESC CMPs
1.5.1
Brief discussion of the monitoring results of the
following activities for ESC CMPs is presented in this Monthly EM&A Report for May 2017:
·
Water Column Profiling of ESC CMP Vd in May 2017; and
·
Routine Water Quality Monitoring of ESC CMP V in May 2017.
1.5.2
Water Column Profiling of ESC CMP Vd – May 2017
1.5.3
Water Column Profiling was undertaken at a total of two sampling stations (Upstream
and Downstream stations) on 16 May 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 wet season period (April to October) of 2006 - 2015 from stations in
the Northwestern Water Control Zone (WCZ), where the
ESC CMPs are located ([6]). 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 May 2017 indicated that levels of DO and pH complied with the WQOs at both Downstream
and Upstream stations (Table B2 of Annex B). In addition, 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 May 2017 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
– May 2017
1.5.8
Routine Water Quality Monitoring of ESC CMP V was undertaken on 18 May 2017. 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 May 2017 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 May 2017 indicated that the levels of pH and DO complied with
the WQOs at all stations (Impact, Intermediate, Reference and Ma Wan stations)
in May 2017 (Table B3 of Annex B; Figures 1 and 3 of Annex C).
Levels of Salinity at most stations also complied with WQO, except for
Ma Wan station (Table B3 of Annex B; Figure 5 of Annex C).
The higher Salinities recorded at Ma Wan station are likely to be caused
by the larger separation distance to Pearl River mouth, which release a large
amount of freshwater runoff in the area during flooding, when compared to the
Reference stations.
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 May 2017.
Laboratory Measurements
1.5.12
Laboratory analysis of May 2017 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 May 2017 samples and the concentrations of these metals and metalloids were similar amongst stations (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 May 2017 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 Pearl River, the North
Western WCZ has historically experienced higher levels of TIN ([7]). 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)
were relatively similar amongst all stations in May 2017 (Table B4 of Annex B; Figure 8 of Annex C). Levels of 5-day Biochemical Oxygen
Demand (BOD5) were relatively similar amongst all stations in May 2017 (Table B4 of Annex B; Figure 9 of Annex C).
1.5.14
Analyses of results for May 2017 indicated that the SS levels complied with the WQO (11.0 mg/L for wet season) and 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 May 2017.
Detailed statistical analysis will be presented in the Quarterly Report
to investigate any spatial and temporal trends of potential concern.
1.6
Brief
Discussion of the Monitoring Results for SB CMPs
1.6.1
Brief discussion of
the monitoring results of the following activities for SB CMPs is presented in
this Monthly EM&A Report for May
2017:
·
Water Quality Monitoring during Capping Operations of SB CMPs
in May 2017.
1.6.2
Water Quality Monitoring during Capping of SB CMPs – May
2017
1.6.3
Capping works at SB CMP 2
were conducted in May 2017 to supplement and revert
the portion of consolidated capping layer to design level and is expected to be
completed by December 2017. The monitoring results obtained during May 2017 sampling in the wet season have been assessed for compliance with the
WQOs (see Section 1.5.3 for details).
Levels of DO
and Turbidity were also assessed for compliance with the Action and Limit
Levels (see Table B5 of Annex B for details). A total of fourteen (14) monitoring
stations were sampled in May 2017 as shown in Figure 1.3. Graphical
presentation of the monitoring results is shown in Figures 11 - 20 of Annex C.
In-situ Measurements
1.6.4
The levels of pH at all stations in May 2017 complied with the WQO (Table B6 of Annex B; Figure 11 of Annex C).
The levels of Turbidity at all stations complied with the Action
and Limit levels in May 2017 (Table B6 of Annex B;
Figure 12 of Annex C).
The
levels of DO at all
stations complied with the WQO and the Action and Limit levels in May 2017 (Table B6 of Annex B; Figure 14 of Annex C). The levels of Salinity at Impact,
Intermediate, Ma Wan, Sham Shui Kok
and Tai Mo To stations are higher than the WQO in May 2017 (Table B6 of Annex B; Figure 16 of Annex C). The Salinities at these stations were higher or above the WQO as they were located further away from
the Tai Ho Bay and Reference stations which experienced less freshwater runoff
from the nearby streams and Pearl River mouth.
Laboratory Measurements
1.6.5
The concentrations of SS were higher than the
WQO (11.0 mg/L
for wet season) at Tai Mo To station in May 2017 (Table B6 of Annex B; Figure 17 of Annex C).
However,
levels of SS at all
stations complied with the Action and Limit Levels (Table B5
and B6 of Annex B).
1.6.6
For nutrients, concentrations of NH3-N were relatively
similar amongst all stations (Table B6 of Annex B; Figure 18 of Annex C).
The levels of TIN at all stations were higher the WQO of 0.5 mg/L (Table B6 of Annex B; Figure 19 of Annex C).
As discussed in Section 1.5.13, the North Western WCZ has historically
experienced higher levels of TIN and such exceedances of TIN WQO at all
stations are unlikely to be caused by the capping operation at CMP 2. Levels of BOD5 were relatively
similar amongst all stations (Table B6 of Annex B; Figure 20 of Annex C).
1.6.7
Overall, the monitoring results indicated that
the capping operation at CMP 2 did not appear to cause any unacceptable
deterioration in water quality in May 2017.
Statistical
analysis will be undertaken and presented in the quarterly report to
investigate whether the capping operations at CMP 2 is causing any unacceptable
impacts in water quality of the area.
1.7
Activities Scheduled for the
Next Month
1.7.1
The following monitoring activities will be conducted
in the next monthly period of June 2017 for ESC CMP V (see Annex A for the sampling schedule):
·
Water Column Profiling of ESC CMP Vd;
·
Cumulative Impact Sediment
Chemistry of ESC CMPs; and.
·
Pit Specific Sediment Chemistry of ESC CMP Vd.
1.7.2
The following monitoring activities will be conducted
in the next monthly period of June 2017 for SB CMPs (see Annex A for the sampling schedule):
·
Water Quality Monitoring During
Capping of SB CMPs.