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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 2018
Contents
1.1 Background
1.2 Reporting Period
1.3 Details of Sampling
and Laboratory Testing Activities
1.4 Details of
Outstanding Sampling and/or Analysis
1.5 Brief Discussion of
the Monitoring Results for ESC CMP V
1.6 Activities
Scheduled for the Next Month
1.7 Study Programme
Annexes
Annex A Sampling Schedule
Annex B Water Quality Monitoring Results
Annex C Graphical Presentations
Annex D Study Programme
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 August
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
August 2018 covers the EM&A
activities for the reporting month of August 2018.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following monitoring
activities were undertaken for ESC CMP V in August 2018:
·
Water Column Profiling of ESC CMP Vd;
·
Routine Water Quality Monitoring of ESC CMPs;
·
Pit Specific Sediment Chemistry of ESC CMP Vd;
·
Cumulative Impact Sediment
Chemistry of ESC CMPs;
·
Sediment Toxicity Tests of ESC
CMPs; and
·
Demersal Trawling for ESC
CMPs.
1.3.2
The following monitoring activity was undertaken for SB CMP
in August 2018:
·
Benthic Recolonisation Studies of SB CMPs.
1.4
Details of Outstanding Sampling and/or Analysis
1.4.1
No outstanding sampling remained for August 2018.
1.4.2
The following laboratory analyses were still in progress during the
preparation of this monthly report and hence is not presented in this monthly
report:
·
Laboratory analyses of
sediment samples collected for Pit Specific
Sediment Chemistry of ESC CMP Vd in August 2018; and
·
Laboratory analyses of
sediment samples collected for Cumulative Impact Sediment Chemistry of ESC CMP
V in August 2018.
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 August 2018;
·
Laboratory
analyses for Sediment Toxicity Test of
ESC CMP V in August 2018; and
·
Laboratory
analyses of sediment samples collected for Benthic
Recolonisation Studies of SB CMPs in August 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 August 2018:
·
Water Column Profiling of ESC CMP Vd in August 2018;
·
Routine Water Quality Monitoring of ESC CMPs in August 2018;
and
·
Pit Specific
Sediment Chemistry of ESC CMP Vd in July 2018.
1.5.2
Water
Column Profiling of ESC CMP Vd – August 2018
1.5.3
Water Column Profiling
was undertaken at a total of two sampling stations (Upstream and Downstream
stations) on 16 August 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 August 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 August
2018 indicated that the SS levels complied with the WQO and
the Action and Limit Level at both Downstream and Upstream 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 – August 2018
1.5.8
Routine Water Quality Monitoring of ESC CMP V was undertaken on
17 August 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 ten
(10) monitoring stations were sampled in August 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 August 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 August 2018.
1.5.10
The levels of DO and Turbidity
also 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 August 2018.
Laboratory
Measurements
1.5.12
Laboratory analysis of August
2018 results indicated that concentrations of Cadmium, Chromium, Silver and
Mercury were below their limit of reporting at all stations. Arsenic, Nickel, Lead, Copper and Zinc were detected in August 2018 samples at most stations and the
concentrations of these metals and metalloids were similar amongst the 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 August 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 generally similar amongst the stations in August 2018 (Table
B4 of Annex
B; Figure 8 and
9 of Annex
C), except higher BOD5 was detected at Impact
stations.
1.5.14
Analyses of results for August 2018 indicated
that the SS levels at most stations were
lower than the WQO (10.8 mg/L for wet season),
except the exceedance of SS recorded at the Impact stations. However, the 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 August 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 – July 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 on 30 July 2018.
1.5.18
The concentrations of most
inorganic contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at all stations
in July 2018, except the concentration of Arsenic slightly exceeded the LCEL at
the Active-Pit stations ESC-NPAA and ESC-NPAB (Figures 11 and
12 of Annex C). 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 ([5]). It is presumed
that the natural concentrations of Arsenic are similar in onshore and offshore
sediments ([6]), and relatively high Arsenic levels may thus occur
throughout Hong Kong. Therefore,
the LECL 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.
1.5.19
For organic contaminants, the
concentrations of Total Organic Carbon (TOC) were generally similar in July
2018, except higher concentrations of TOC were recorded at the Active-Pit
stations ESC-NPAA and ESC-NPAB (Figure
13 of Annex C).
The concentration of Tributyltin (TBT) was generally similar amongst stations in
July 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 July 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 July
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 September 2018
for ESC
CMP V (see Annex A for the sampling schedule):
·
Water Column Profiling of ESC CMP Vd; and
·
Pit Specific Sediment Chemistry of ESC CMP Vd.