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 JuLY 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 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 ()()()()(). 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 July 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
July 2017 covers the EM&A activities for the reporting month of July 2017.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following monitoring activities were undertaken for ESC
CMP V in July 2017:
·
Demersal Trawling for ESC CMPs was undertaken on 5 and 6 July 2017;
·
Pit Specific Sediment Chemistry of ESC CMP Vd was undertaken on 12 July 2017;
·
Routine Water Quality Monitoring of ESC CMP V was undertaken on 13 July 2017;
·
Water Column Profiling of ESC CMP Vd was undertaken on 14 July 2017;
·
Sediment Chemistry after a Major
Storm of ESC CMPs was
undertaken on 25 July 2017; and
·
Water Quality Monitoring during
Dredging of ESC CMP Vb was undertaken on 31 July
2017.
1.3.2
No monitoring activities were
scheduled to be undertaken for SB CMPs in July 2017.
1.4
Details of Outstanding
Sampling and/or Analysis
1.4.1
No outstanding sampling remained for July 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 CMPs
in July 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 CMPs
in July 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 July 2017:
·
Water Quality Monitoring During
Dredging of ESC CMP Vb in July 2017;
·
Water Column Profiling of ESC CMP Vd in July 2017;
·
Routine Water Quality Monitoring of ESC CMP V in July 2017;
·
Pit Specific Sediment
Chemistry of ESC CMP Vd in
June and July 2017;
·
Cumulative Impact Sediment Chemistry of ESC CMPs in June 2017; and
·
Sediment Chemistry after a Major
Storm of ESC CMPs
in June 2017.
1.5.2
Impact
Water Quality Monitoring during Dredging Operations of ESC CMP Vb – July 2017
1.5.3
Dredging activities for ESC CMP Vb commenced on 29 July 2017
and water quality monitoring was conducted three times per week during the
reporting period starting from 31 July
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 July 2017 is reported in Annex C. Levels of DO, Turbidity and SS complied
with the Action and Limit Levels at all
stations.
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 – July 2017
1.5.7
Water
Column Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 14 July 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 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
1.5.8
Analyses of results for July 2017 indicated that levels of DO 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). Levels of Salinity at
Downstream station were higher than the WQO. The higher salinity recorded at
Downstream station is likely to be caused by its larger separation distance
from the Pearl River mouth, which is a key source of freshwater inputs in the
area, when compared to the Upstream station.
Laboratory
Measurements for Suspended Solids (SS)
1.5.9
Analyses of results for July 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 – July 2017
1.5.12
Routine
Water Quality Monitoring of ESC CMP V was undertaken on 13 July 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 B4 and
B5 of Annex B and Figures 1 - 10 of Annex D. A total of
sixteen (16) monitoring stations were sampled in July 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 July 2017 indicated that the levels of pH,
Salinity and DO complied with the WQOs at all
stations (Impact, Intermediate, Reference and Ma Wan stations) in July 2017 (Table B4 of Annex
B; Figures 1, 3 and 5 of Annex D).
1.5.1
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).
1.5.2
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 July 2017.
Laboratory Measurements
1.5.3
Laboratory analysis of July 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 July 2017 samples and the concentrations of these metals and metalloids were similar amongst stations (Table B5 of Annex
B; Figure 7 of Annex
D).
1.5.4
For nutrients, concentrations of Total Inorganic Nitrogen
(TIN) at all stations in July 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 ([8]). 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
July 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 July 2017 (Table B5 of Annex
B; Figure 9 of Annex
D).
1.5.5
Analyses of results for July 2017 indicated
that the SS levels at Impact station were
higher than the WQO (11.0 mg/L for wet season), however the concentrations of SS were below the
Action and Limit Levels at all stations (Tables B1 and B4 of Annex
B; Figure 10 of Annex
D).
1.5.6
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 July 2017.
Detailed statistical analysis will be presented in the Quarterly Report
to investigate any spatial and temporal trends of potential concern.
1.5.7
Pit
Specific Sediment Chemistry of ESC CMP Vd – June and July 2017
1.5.8
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 June and July
2017.
1.5.9
The concentrations of all inorganic contaminants were
lower than the Lower Chemical Exceedance Level (LCEL) at all stations in June and July 2017, except Silver, Copper and Zinc in
July 2017 (Figures 11,
12, 15 and 16 of Annex D). In July 2017,
concentrations of Silver, Copper and Zinc exceeded the LCEL at Active Pit
station ESC-NPAA (Figure 15 of Annex D).
1.5.10
For organic contaminants, the concentrations of Total Organic
Carbon (TOC) were similar amongst the stations in June and July 2017 (Figures 13 and 17 of Annex D). The concentrations of Tributyltin (TBT) were higher at Active Pit stations ESC-NPAA
and ESC-NPAB in June and July 2017 (Figures 14 and 18 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 June and July 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 June and July 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 CMPs – June 2017
1.5.13
Monitoring locations for Cumulative
Impact Sediment Chemistry for ESC
CMPs are shown in Figure 1.5. A total of nine (9)
monitoring stations were sampled in June 2017.
1.5.14
Analyses of results for the Cumulative
Impact Sediment Chemistry Monitoring indicated that
the concentrations of all inorganic contaminants were below
the LCEL in June 2017 (Figures 19
and 20 of Annex D).
1.5.15
For
organic contaminants, concentrations of TOC and TBT were recorded to be higher at Ma Wan station (Figures
21 and 22 of Annex D). Low and High Molecular Weight PAHs, PCBs, DDT and DDE concentrations were
recorded below the limit of reporting at all stations.
1.5.16
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 June 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.
1.5.17
Sediment
Chemistry after a Major Storm of ESC CMPs – June 2017
1.5.18
Sampling for Sediment Chemistry
after a Major Storm Event was conducted at nine (9) monitoring stations (Figure 1.5) on 19 June 2017 after the visit of tropical cyclone
Merbok, which led to the issue of Gale or Storm Wind Signal No.8 on 12 June
2017. The track of Merbok is shown
in Figure 1.6.
Figure 1.6 Track
of Tropical Cyclone Merbok from 11 to 13 June 2017 (Source: Hong Kong Observatory)
1.5.19
Analyses of results for the Sediment
Chemistry after a Major Storm indicated that the concentrations
of all inorganic contaminants were below the LCEL (Figures 23 and 24
of Annex D).
1.5.20
Overall, there appeared to be no
evidence showing the failure of CMPs in retaining disposed mud or causing
contamination of sediments after the major storm event in June 2017.
1.6
Activities Scheduled for the
Next Month
1.6.1
The following monitoring activities will be conducted in the next monthly
period of August 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;
·
Routine Water Quality
Monitoring of ESC CMP Vd;
·
Pit Specific Sediment Chemistry of ESC CMP Vd;
·
Cumulative Impact Sediment
Chemistry of ESC CMPs;
·
Sediment Toxicity Tests of ESC
CMPs; and
·
Demersal Trawling of ESC
CMPs.
1.6.2
The following monitoring activities will be conducted in the next monthly
period of August 2017 for SB CMPs (see Annex A for the sampling schedule):
·
Water Quality Monitoring During
Capping of SB CMPs; and
·
Benthic Recolonisation Studies of
SB CMPs.
1.7.1
A summary of the Study programme is
presented in Annex E.