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 2019
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,
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.
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). The scheduled EM&A programme for SB CMPs was completed in
December 2018. Detailed works schedule for ESC CMP V is shown in Figure 1.1. In April 2019, disposal of
contaminated mud at ESC CMP Vd was undertaken.
Figure 1.1 Works
Schedule for ESC CMP V
This Monthly EM&A Report for April 2019 covers the EM&A activities for
the reporting month of April 2019.
Details of Sampling and Laboratory Testing Activities
monitoring activities were undertaken for ESC CMP V in
Water Column Profiling of ESC CMP Vd;
Routine Water Quality Monitoring of ESC CMPs; and
Pit Specific Sediment Chemistry of ESC CMP Vd.
Details of Outstanding Sampling and/or Analysis
No outstanding sampling remained for April
Brief Discussion of the
Monitoring Results for ESC CMP V
discussion of the monitoring results of the following activities for ESC CMP V
is presented in this Monthly
EM&A Report for April 2019:
Water Column Profiling of ESC CMP Vd in April 2019;
Routine Water Quality Monitoring of ESC CMPs in April 2019; and
Pit Specific Sediment
Chemistry of ESC CMP Vd in
Water Column Profiling of ESC CMP Vd
– April 2019
Water Column Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 4 April 2019. 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
2008 - 2017 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).
results for April 2019 indicated that levels of Salinity, pH and DO complied
with the WQOs at both Downstream and Upstream stations (Table B2 of Annex B). 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)
results for April 2019 indicated that the SS levels at both Downstream and
Upstream stations complied with the WQO and the Action and Limit Levels at both
Downstream and Upstream stations (Tables B1 and B2 of Annex B).
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
Routine Water Quality Monitoring of
ESC CMPs – April 2019
Routine Water Quality Monitoring of ESC CMPs was undertaken on 3 April 2019. 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 2019 as shown in Figure 1.2.
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 2019 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 2019, except the levels of Salinity were higher
than WQO at Ma Wan station. 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.
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).
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 2019.
analysis of April 2019 results indicated that concentrations of Silver were below their limit
of reporting at all stations. Arsenic, Cadmium, Chromium, Copper Lead,
Mercury, Nickel and Zinc were detected in April 2019 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).
concentrations of Total Inorganic Nitrogen (TIN) at Reference, Impact and
Intermediate stations were higher than the WQO (0.5 mg/L) in April 2019 (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 (). 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 April 2019 (Table B4 of Annex B; Figure 8 and 9 of Annex C).
results for April 2019 indicated that the SS levels were complied with the WQO (10.8 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).
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 2019. Detailed statistical analysis will be presented in
the Quarterly Report to investigate any spatial and temporal trends of
Pit Specific Sediment Chemistry of
ESC CMP Vd – April 2019
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 2 April
of all inorganic contaminants were lower than the Lower Chemical Exceedance
Level (LCEL) at most stations, except the concentrations of Arsenic were higher
than the LCEL at Active Pit station ESC-NPAA, the concentrations of Lead,
Mercury and Silver were higher than the LCEL at Active Pit stations ESC-NPAB
and the concentrations of Copper were higher than the Upper Chemical Exceedance
Level (UCEL) at Active Pit station ESC-NPAB (Figures
11 and 12 of Annex C).
For organic contaminants, the
concentrations of Total Organic Carbon (TOC) varied between stations in April 2019 (Figure
13 of Annex C). The concentrations of Tributyltin (TBT) were higher
at Active-Pit station ESC-NPAB in April 2019 (Figure 14 of
Annex C). The concentrations of Low and High Molecular Weight
Polycyclic Aromatic Hydrocarbons (PAHs) were higher than LCEL at Active-Pit
station ESC-NPAB in April 2019 (Figure 15 of Annex C). Total
Polychlorinated Biphenyls (PCBs), Total dichloro-diphenyl-trichloroethane (DDT)
and 4,4’-dichlorodiphenyldichloroethylene (DDE) concentrations were below the
limit of reporting at all stations.
Whilst the average
concentration of Arsenic in the Earth’s crust is generally ~2 mg/kg,
significantly higher Arsenic concentrations (median = 14 mg/kg) have been
recorded in Hong Kong’s onshore sediments (). It is presumed that the natural
concentrations of Arsenic are similar in onshore and offshore sediments (), 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.
Considering that the higher
levels of Copper, Lead, Mercury, Silver and Low and High
Molecular Weight PAHs occurred within one Active-Pit station ESC-NPAB only but
not at the Pit-Edge and Near-Pit stations, 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 2019. 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
Activities Scheduled for the Next Month
The following monitoring activities will be
conducted in the next monthly period of May 2019 for ESC CMP V (see Annex A for the sampling schedule ()):
· Water Column
Profiling of ESC CMP Vd;
· Routine Water
Quality Monitoring of ESC CMPs; and
· Pit Specific
Sediment Chemistry of ESC CMP Vd.
A summary of the
Study Programme is presented in Annex D.