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 August 2017
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 uncontamin ated
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 () (). 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 August 2017, the following works were
being undertaken:
· Dredging operation at ESC CMP Vb;
· Disposal of contaminated mud at
ESC CMP Vd; and
· Capping operation at SB CMP 2.
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
August 2017 covers the EM&A activities for
the reporting month of August 2017.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following monitoring activities were undertaken for ESC
CMP V in August 2017:
·
Demersal Trawling for ESC CMP V was undertaken on 2 and 3 August 2017;
·
Water Quality Monitoring during
Dredging of ESC CMP Vb was undertaken on 2, 4, 7, 9, 11, 21, 25, 28 and 30 August 2017;
·
Pit Specific Sediment Chemistry of ESC CMP Vd was
undertaken on 5 August 2017;
·
Sediment Toxicity Tests of ESC
CMP V was undertaken on 8 and 10 August
2017;
·
Cumulative Impact Sediment
Chemistry of ESC CMP V was undertaken on 8 and 10 August
2017;
·
Water Column Profiling of ESC CMP Vd was
undertaken on 12 August 2017;
·
Routine Water Quality Monitoring of ESC CMP V was undertaken on 15 August 2017; and
·
Sediment Chemistry after a Major
Storm of ESC CMP V was undertaken on 31 August
2017.
1.3.2
The following monitoring activities were undertaken for SB
CMPs in August 2017:
·
Benthic Recolonisation
Studies of SB CMPs was
undertaken on 29 August 2017; and
·
Water Quality Monitoring During Capping of SB CMPs was undertaken on 17 August 2017.
1.4
Details of Outstanding
Sampling and/or Analysis
1.4.1
No outstanding sampling remained for August 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 Sediment Chemistry after a Major
Storm of ESC CMP V in August 2017.
1.4.3
The following analyses
are in progress and will be presented in the corresponding quarterly report:
· Species identification
of the biota samples collected from Demersal Trawling for ESC CMP V in August 2017;
·
Laboratory
analyses of sediment samples collected for Benthic Recolonisation
Studies of SB CMPs in August 2017; and
· Laboratory analyses
for Sediment Toxicity Test of ESC
CMP V in
August 2017.
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 August 2017:
·
Water Quality Monitoring During
Dredging of ESC CMP Vb in August 2017;
·
Water Column Profiling of ESC CMP Vd in August 2017;
·
Routine Water Quality Monitoring of ESC CMP V in August 2017;
·
Pit Specific Sediment
Chemistry of ESC CMP Vd in August 2017;
·
Cumulative Impact Sediment Chemistry of ESC CMP V in August 2017; and
·
Sediment Chemistry after a Major
Storm of ESC CMP V in July 2017.
1.5.2
Impact
Water Quality Monitoring during Dredging Operations of ESC CMP Vb – August 2017
1.5.3
Dredging activities were carried out on 1 – 11, 17 – 22, 25 – 26, 28 – 31 August 2017 during this reporting period and monitoring was conducted
on 2, 4, 7, 9, 11, 21, 25, 28
and 30 August 2017. During each survey day, monitoring was
conducted during both mid-ebb and mid-flood tides at two Reference (Upstream)
stations and five Impact (Downstream) stations around the dredging operations at ESC CMP
Vb. Monitoring was also conducted
at one Sensitive Receiver station situated in Ma Wan.
A total of eight (8) stations were monitored and locations of the
sampling stations are shown in Figure
1.2. Levels of Dissolved Oxygen (DO),
Turbidity and Suspended Solid (SS) were assessed for compliance with the Action
and Limit Levels (see Table B1 of Annex B for details) set in the Baseline
Monitoring Report ().
1.5.4
Monitoring results are presented in Table B2 of Annex
B. Daily dredging volume in August 2017 is reported in Annex C. Levels of DO,
Turbidity and SS generally complied with the Action and Limit Levels (see Table
B1 of Annex B for details) set in the Baseline Monitoring Report (),
except for the following occasions discussed in Table 1.1 below.
1.5.5
The results indicated that the dredging operations at ESC
CMP Vb did not appear to cause any unacceptable
deterioration in water quality during this reporting period. Therefore, no further action, except for
those recommended in the Environmental Permit (EP-312/2008/A), are considered necessary for the dredging operations.
1.5.6
Water
Column Profiling of ESC CMP Vd
– August 2017
1.5.7
Water
Column Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 12 August 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 (). For Salinity, the averaged value
obtained from the Reference (Upstream) station was used for the basis as the WQO. Levels of 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
1.5.8
Analyses of results for August 2017 indicated that levels of
DO, Salinity and pH complied with the WQOs at both Downstream and Upstream stations (Table
B3
of Annex
B). In addition, levels of DO and Turbidity at all stations complied with the Action and Limit
Levels (Tables B1 and B3 of Annex B).
Laboratory
Measurements for Suspended Solids (SS)
1.5.9
Analyses of results for August 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 B3 of Annex
B).
1.5.10
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.
1.5.11
Routine
Water Quality Monitoring of ESC CMP V – August 2017
1.5.12
Routine
Water Quality Monitoring of ESC CMP V was undertaken on 15 August 2017. The monitoring results have been assessed for
compliance with the WQOs (see Section 1.5.7 for details). The monitoring results are shown in Tables B4 and
B5 of Annex
B and Figures 1 - 10 of Annex
D. A total of ten (10) monitoring stations
were sampled in August 2017 as shown in Figure 1.3.
In-situ Measurements
1.5.13
Graphical presentation of the monitoring results
(Temperature, DO, pH, Salinity and Turbidity) is shown in Figures
1 - 6 of Annex D. Analyses of results for August 2017 indicated that the levels of pH
and DO complied with the WQOs at all
stations (Impact, Intermediate, Reference and Ma Wan stations) in August 2017 (Table B4 of Annex
B; Figures 1 and 3 of Annex D). Levels of Salinity at most stations also
complied with WQO, except for Ma Wan station (Table B4 of Annex B; Figure 5 of Annex D). 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.
1.5.14
The levels of DO and Turbidity
complied with the Action and Limit Levels at all stations (Table
B4 of Annex
B; Figures 3 and 6 of Annex
D).
1.5.15
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 August 2017.
Laboratory Measurements
1.5.16
Laboratory analysis of August 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 August 2017 samples and the concentrations of these metals and metalloids were similar amongst stations (Table B5 of Annex
B; Figure 7 of Annex
D).
1.5.17
For nutrients, concentrations of Total Inorganic Nitrogen
(TIN) at all stations in August 2017 were higher
than the WQO (0.5 mg/L) (Table B5 of Annex B; Figure 8 of Annex D). It should be
noted that due to the effect of Pearl River, the North Western WCZ has
historically experienced higher levels of TIN ([6]). 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 August 2017 (Table B5 of Annex
B; Figure 8 of Annex D). Levels of 5-day Biochemical Oxygen
Demand (BOD5) were higher at Ma Wan station in August 2017 (Table B5 of Annex
B; Figure 9 of Annex
D).
1.5.18
Analyses of results for August 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
D).
1.5.19
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 August 2017. Detailed statistical analysis will be
presented in the Quarterly Report to investigate any spatial and temporal
trends of potential concern.
1.5.20
Pit
Specific Sediment Chemistry of ESC CMP Vd
– August 2017
1.5.21
Monitoring locations for Pit
Specific Sediment Chemistry for ESC CMP Vd are shown in Figure 1.4. A total of six
(6) monitoring stations were sampled in August 2017.
1.5.22
The concentrations of most inorganic contaminants were
lower than the Lower Chemical Exceedance Level (LCEL) at all stations in August 2017, except Silver and Copper in August 2017 (Figures
11 and 12 of Annex D). In August
2017, concentrations of Silver and Copper exceeded the LCEL at Active Pit
station ESC-NPAB (Figures 11 and 12
of Annex
D).
1.5.23
For organic contaminants, the concentrations of Total
Organic Carbon (TOC) were higher at Active Pit station ESC-NPAB in August 2017
(Figure 13 of Annex D). The concentrations of Tributyltin (TBT) were higher at Active Pit stations ESC-NPAA
and ESC-NPAB in August 2017 (Figure 14 of Annex
D). 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 August 2017.
1.5.24
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
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.
1.5.25
Cumulative
Impact Sediment Chemistry of ESC CMP V – August 2017
1.5.26
Monitoring locations for Cumulative Impact Sediment
Chemistry for ESC CMP V are shown in Figure 1.5. A total of
nine (9) monitoring stations were sampled in August 2017.
1.5.27
Analyses of results for the Cumulative
Impact Sediment Chemistry Monitoring indicated that
the concentrations of all inorganic contaminants were below
the LCEL in August 2017 (Figures 15
and 16 of Annex D).
1.5.28
For organic contaminants, concentrations of TOC and TBT were recorded to be higher at Ma Wan station (Figures 17 and 18 of Annex D). Low and High Molecular Weight PAHs, PCBs, DDT and DDE concentrations were
recorded below the limit of reporting at all stations.
1.5.29
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 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.
1.5.30
Sediment
Chemistry after a Major Storm of ESC CMP V – July 2017
1.5.31
Sampling for Sediment Chemistry
after a Major Storm Event was conducted at nine (9) monitoring stations (Figure
1.5) on 25 July 2017 after the visit of tropical cyclone Roke, which led to the issue of Gale or Storm Wind Signal
No.8 on 23 July 2017. The track of Roke is shown in Figure 1.6.
Figure 1.6 Track
of Tropical Cyclone Roke from 21 to 23 July 2017 (Source: Hong Kong Observatory)
1.5.32
Analyses of results for the Sediment
Chemistry after a Major Storm indicated that the concentrations
of all inorganic contaminants were below the LCEL (Figures 19 and 20
of Annex D).
1.5.33
Overall, there appeared to be no
evidence showing the failure of ESC CMP V in retaining disposed mud or causing contamination of sediments after
the major storm event in July 2017.
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 August 2017:
·
Water Quality Monitoring during Capping Operations of SB CMPs
in August 2017.
1.6.2
Water
Quality Monitoring during Capping of SB CMPs – August
2017
1.6.3
Capping works at SB CMP 2 were
conducted in August 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
August 2017 sampling in the wet season have been assessed for compliance with the WQOs (see Section 1.5.7 for
details). Levels of DO and Turbidity were also assessed for compliance with the
Action and Limit Levels (see Table B6 of Annex
B for details). A total of fourteen (14) monitoring stations were sampled in August 2017 as shown in Figure 1.7. Graphical
presentation of the monitoring results is shown in Figures 21 - 30 of Annex D.
In-situ Measurements
1.6.4
The levels of pH at all stations in August 2017 complied with the WQO (Table
B7 of Annex B; Figure 21 of Annex D). The
levels of Turbidity at all stations complied
with the Action and Limit levels in August 2017 (Table B7 of Annex B; Figure 22 of Annex
D). The levels of DO at all stations complied with the WQO and the Action and Limit
levels in August 2017, except for Sham Shui Kok station (Table B7 of Annex B; Figure 24 of Annex
D). The level of DO at Sham Shui Kok station is lower than
the WQO, however this station is located further away from the works area of
CMP 2 when compared to the Impact, Intermediate and Reference stations at which
the levels of DO complied with the WQO and the Action and Limit Levels during
the same tidal period. The levels
of Salinity at Impact, Intermediate, Ma Wan, Sham Shui Kok and Tai Mo To stations
are higher than the WQOmax in August 2017 (Table B7 of Annex
B; Figure 26 of Annex D). The Salinities at these stations were higher than the WQOmax
as they were located further away from the Tai Ho Bay and Reference stations,
thus experiencing less freshwater runoff from the nearby streams. The levels of Salinity at Tai Ho Bay 1 and
2 stations are lower than the WQOmin in August 2017 (Table B7 of Annex
B; Figure 26 of Annex D). The lower
Salinity levels at Tai Ho Bay 1 and 2 stations are likely to be caused by the freshwater runoff from the nearby streams.
Laboratory Measurements
1.6.5
The concentrations of SS were higher than the WQO (11.0 mg/L for wet season) at Intermediate, Sham Shui Kok, Tai Mo To and Tai Ho Bay 1 station in August 2017 (Table B7 of Annex B; Figure 27 of Annex D). However, levels of SS at most stations complied with the Action and Limit Levels, except
at Sham Shui Kok and Tai Ho
Bay 1 stations (Tables
B6 and B7 of Annex B). Sham Shui Kok and Tai Ho Bay 1 stations are located further away from
the works area of CMP 2 when compared to Impact, Intermediate and Reference
stations at which the levels of SS did not exceed the Action and Limit Levels
during the same tidal period.
1.6.6
For nutrients, concentrations of NH3-N were relatively
similar amongst all stations, except the concentrations of NH3-N recorded at Impact
station was lower than the other stations (Table B7 of Annex B; Figure 28 of Annex
D). The levels of TIN at all stations were higher the WQO of 0.5 mg/L (Table
B7 of Annex
B; Figure 29 of Annex D), except for Ma Wan station. It is important to note that due to the
effect of the Pearl River, the North
Western WCZ has historically experienced higher levels of TIN ().
The exceedances of TIN WQO at these stations are unlikely to be caused
by the capping operation at CMP 2. Levels of BOD5 were higher at Tai Mo To and Tai Ho Bay 2 stations in August 2017 (Table B7 of Annex
B; Figure 30 of Annex D).
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 August 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 September
2017 for ESC CMP V (see Annex
A for the sampling schedule):
·
Water Quality Monitoring During
Dredging of ESC CMP Vb;
·
Water Column Profiling of ESC CMP Vd; and
·
Pit Specific Sediment Chemistry of ESC CMP Vd.
1.7.2
No monitoring activities are scheduled
in the next monthly period of September 2017 for SB CMPs.
1.8.1
A summary of the Study programme is
presented in Annex
E.
