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 MAy 2018
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 May 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
May 2018 covers the
EM&A activities for the reporting month of May 2018.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following
monitoring activities were undertaken for ESC CMP V in May 2018:
·
Water Column Profiling of ESC CMP Vd;
·
Routine Water Quality Monitoring of ESC CMP Vd; and
·
Pit Specific Sediment Chemistry of ESC CMP Vd.
1.3.2
No monitoring
activities were undertaken for SB CMP in May 2018.
1.4
Details of Outstanding Sampling and/or Analysis
1.4.1
No outstanding sampling remained for May 2018.
1.4.2
The following laboratory analysis was 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 for ESC CMP Vd in
May 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 May 2018:
·
Water Column Profiling of ESC CMP Vd in May 2018; and
·
Routine Water Quality Monitoring of ESC CMP Vd in May 2018.
1.5.2
Water
Column Profiling of ESC CMP Vd – May 2018
1.5.3
Water Column
Profiling was undertaken at a total of two
sampling stations (Upstream and Downstream stations) on 26 May 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 May 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 May 2018 indicated that the SS levels complied with the WQO and the
Action and Limit Levels at both Upstream and Downstream 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 – May 2018
1.5.8
Routine Water
Quality Monitoring of ESC CMP V was undertaken on 23 May 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 May 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 May 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 May 2018, except slightly higher
Salinity was recorded at Ma Wan station (Table B3 of Annex B; Figures 1, 3 and 5 of Annex C). Ma Wan
station is located further away from other monitoring stations located closer
to the ESC CMP Vd where levels of Salinity complied with WQO requirements. It is thus considered that higher levels
of Salinity recorded in Ma Wan station was not related to the disposal
operation at ESC CMP Vd.
1.5.10
The levels of DO and
Turbidity 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 May 2018.
Laboratory Measurements
1.5.12
Laboratory analysis of May 2018 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 May 2018 samples at most stations and the concentrations of these metals and metalloids were similar amongst most 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 May 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 most stations in May 2018 (Table B4 of Annex B; Figure 8 and
9 of Annex C), except generally higher BOD5 was detected at Ma Wan station.
1.5.14
Analyses of
results for May 2018 indicated that the SS levels at
all stations were lower than the WQO (10.8 mg/L
for wet season) and 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 May
2018. Detailed statistical analysis
will be presented in the Quarterly Report to investigate any spatial and
temporal trends of potential concern.
1.6
Activities Scheduled for the
Next Month
1.6.1
The following monitoring activities will be conducted in the next monthly
period of June 2018 for ESC
CMP V (see Annex
A for the sampling schedule):
·
Water Column Profiling of ESC CMP Vd;
·
Pit Specific Sediment Chemistry of ESC CMP Vd;
and
· Cumulative
Impact Sediment Chemistry of ESC CMP V.