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 January 2019
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). 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 January 2019, disposal of
contaminated mud at ESC CMP Vd was undertaken.
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 January 2019
covers the EM&A
activities for the reporting month of January 2019.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following monitoring
activities were undertaken for ESC CMP V in January
2019:
· Water Column Profiling of ESC CMP Vd;
· Routine Water Quality Monitoring of ESC CMPs;
· Pit Specific Sediment Chemistry of ESC CMP Vd; and
· Demersal Trawling for ESC CMPs.
1.4
Details of Outstanding
Sampling and/or Analysis
1.4.1
No outstanding sampling remained for January
2019.
1.4.2
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 January 2019.
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 January 2019:
· Water Column Profiling of ESC CMP Vd in January 2019;
· Routine Water Quality Monitoring of ESC CMPs in January 2019; and
· Pit Specific Sediment Chemistry of ESC CMP Vd in January 2019.
1.5.2
Water Column Profiling of ESC CMP Vd – January 2019
1.5.3
Water Column Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 4 January 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 dry season period
(November to March) 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
January 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)
1.5.5
Analyses of results for
January 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).
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
CMPs – January 2019
1.5.8
Routine Water Quality Monitoring of ESC CMPs was
undertaken on 9 January 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 ten (10) monitoring stations were sampled in January 2019 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 January
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 January 2019.
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 January
2019.
Laboratory Measurements
1.5.12
Laboratory analysis of January 2019 results indicated that
concentrations of Cadmium, Silver and Mercury were below their limit of
reporting at all stations, while the concentrations of Chromium, Lead and
Nickel were below their limit of reporting at most stations expect at Impact
stations. Arsenic, Copper and Zinc were detected
in January 2019 samples at all
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 January 2019 complied with the WQO (Table
B4 of Annex B; Figure 8 of Annex C).
Concentrations of Ammonia Nitrogen (NH3-N) and 5-day Biochemical
Oxygen Demand (BOD5) were generally similar amongst the stations in January 2019 (Table B4 of Annex B; Figure 8 and 9 of Annex C).
1.5.14
Analyses of results for
January 2019 indicated that the SS levels were higher than the WQO (12.8 mg/L for dry season) for Reference, Impact and
Intermediate stations, however, the SS levels complied 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 January
2019. 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 – January 2019
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 3 January 2019.
1.5.18 The concentrations of all inorganic
contaminants were lower than the Lower Chemical Exceedance Level (LCEL) at
Pit-Edge and Near-Pit stations in January 2019. The
concentrations of Arsenic were higher than the LCEL at Active Pit stations
ESC-NPAA and ESC-NPAB. The concentrations of Chromium were higher than
the LCEL at Active Pit station ESC-NPAB and the concentrations of Copper, Lead,
Mercury, Nickel, Silver and Zinc were higher than the Upper Chemical Exceedance
Level (UCEL) at Active Pit station ESC-NPAB (Figures 11 and 12 of Annex C).
1.5.19 For organic contaminants, the concentrations of Total Organic
Carbon (TOC) varied between stations and were generally higher at Active-Pit
ESC-NPAB station in January 2019 (Figure 13 of Annex C). Tributyltin (TBT), Total Polychlorinated Biphenyls
(PCBs), Total dichloro-diphenyl-trichloroethane
(DDT) and 4,4’-dichlorodiphenyldichloroethylene (DDE)
concentrations were below the limit of reporting at all stations, while Low and
High Molecular Weight Polycyclic Aromatic Hydrocarbons (PAHs) exceeded the UCEL
at Active-Pit ESC-NPAB station in January 2019.
1.5.20
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 ([4]). It is presumed that the
natural concentrations of Arsenic are similar in onshore and offshore sediments ([5]), 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.
1.5.21 Considering
that the higher levels of other contaminants 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 January 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 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 February 2019 for ESC CMP V (see Annex A
for the sampling schedule ([6])):
· 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.
1.7
Study Programme
1.7.1
A summary of the Study
Programme is presented in Annex D.
([1]) ERM (2013) Final Report. Submitted under Agreement No. CE 4/2009 (EP) Environmental Monitoring and Audit for Contaminated Mud Pit at East Sha Chau. For CEDD.
([2]) ERM (2017) Final Report. Submitted under Agreement No. CE 23/2012 (EP) Environmental Monitoring and Audit for Contaminated Mud Pits to the South of The Brothers and at East Sha Chau (2012 - 2017). For CEDD.
([4]) Sewell RJ (1999) Geochemical Atlas of Hong Kong. Geotechnical Engineering Office, Government of the Hong Kong Special Administrative Region