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) - Investigation
47th MONTHLY PROGRESS REPORT FOR July 2016
Since early 1990s, contaminated sediment () arising from various construction works
(e.g. dredging and reclamation projects) in Hong Kong
has been disposed of at a series of seabed pits at East of Sha
Chau (ESC). In
late 2008, a review indicated that the existing and planned facilities at ESC
would not be able to meet the disposal demand after 2012. In order to meet this demand, the Hong Kong
Special Administrative Region Government (HKSARG) decided to implement a new
contained aquatic disposal (CAD) () facility at the South of The Brothers
(SB CMPs) which had been under consideration for a
number of years.
The environmental acceptability of the construction and
operation of the Project had been confirmed by findings of the associated
Environmental Impact Assessment (EIA) study completed in 2005 under Agreement No. CE 12/2002(EP) ().
The Director of Environmental Protection (DEP) approved this EIA report
under the Environmental
Impact Assessment Ordinance (Cap. 499) (EIAO) in September 2005 (EIA Register No.: AEIAR-089/2005).
In accordance with the EIA recommendation, prior to
commencement of construction works for the SB CMPs,
the Civil Engineering and Development Department (CEDD) undertook a detailed
review and update of the EIA findings for the SB site (). Findings of the EIA review undertaken in
2009/ 2010 confirmed that the construction and operation of the SB site had
been predicted to be environmentally acceptable.
(EP-312/2008/A and EP-427/2011A) were issued by the Environmental
Protection Department (EPD) to the CEDD, the Permit Holder, on 28 November 2008
for ESC CMP V and on 23 December 2011 for SB CMPs,
respectively. Under the requirements of
the EPs, an Environmental
Monitoring and Audit (EM&A) programme as set out in the EM&A Manuals ()
is required to be implemented for the CMPs.
The present EM&A programme under Agreement No. CE 23/2012 (EP) covers the dredging,
disposal and capping operations of the SB CMPs
as well as ESC CMPs. Detailed works schedule for ESC CMPs and SB CMPs is shown in Figure
1.1. In July 2016,
the following works were being undertaken:
· Disposal of contaminated mud at ESC CMP Vd; and
· Capping operation at SB CMP 2.
Figure 1.1 Works
Schedule for ESC CMPs and SB CMPs
This 47th Monthly Progress Report covers the EM&A activities for the reporting month of July 2016.
of Sampling and Laboratory Testing Activities
The following monitoring activities have been undertaken for
ESC CMPs in July 2016:
Routine Water Quality Monitoring of ESC CMP Vd
was undertaken on 4 July 2016;
Water Column Profiling of ESC CMP Vd was undertaken on 5 July 2016;
· Pit Specific Sediment
Chemistry of ESC CMP Vd was
undertaken on 6 July 2016; and
· Demersal Trawling of ESC CMP Vd
was undertaken on 27 and 28 July 2016.
No monitoring activities
were scheduled to be undertaken for SB CMPs in July
Details of Outstanding Sampling and/or
No outstanding sampling remained for July 2016.
summary of field activities conducted are presented in Annex A. 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 CMP Vd in July 2016.
Discussion of the Monitoring Results for ESC CMPs
Brief discussion of the
monitoring results of the following activities for ESC CMPs
is presented in this 47th Monthly Progress Report:
· Routine Water Quality
Monitoring of ESC CMP Vd
in July 2016;
Water Column Profiling of ESC CMP Vd in July 2016; and
· Pit Specific Sediment
Chemistry of ESC CMP Vd in July 2016.
Routine Water Quality Monitoring of ESC
CMP Vd – July 2016
Routine Water Quality
Monitoring was undertaken on 4 July
2016. 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 2005 - 2014 from
stations in the Northwestern Water Control Zone
(WCZ), where the ESC CMPs are located (). For Salinity, the averaged value obtained
from the Reference stations 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).
The monitoring results are shown
in Tables B2 and B3 of Annex B and Figures 1 - 10
of Annex C. A total of sixteen (16) monitoring stations
were sampled in July 2016 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 July
indicated that the levels of pH and DO complied with the WQOs at all stations (Impact, Intermediate, Reference and
Ma Wan stations) in July 2016 (Table B2 of Annex B; Figures 1, 2, 3 and 4 of Annex
C). Levels of Salinity at Impact and Intermediate
stations exceeded the WQOs (Table B2 of Annex B; Figure
5 of Annex C). The
lower Salinities recorded at these stations is likely to be caused by the
freshwater discharged from the Pearl River Delta during the summer months which
tend to form a surface layer of lower salinity water at these stations with
shallower depth when compared with the Reference stations.
The levels of DO and Turbidity complied with the Action and
Limit Levels at all stations (Table
B2 of Annex B; Figures 2, 3 and 6 of Annex C).
Overall, in-situ measurement results of
the Routine Water Quality
that the disposal operation at ESC CMP Vd did not
appear to cause any unacceptable impacts in water quality in July
Laboratory analysis of July 2016 results indicated
that concentrations of Cadmium, Chromium, Silver and Mercury were below their
limit of reporting at all stations.
Arsenic, Lead, Nickel, Copper and Zinc were detected in July 2016 samples and the
concentrations of these metals and metalloid were similar amongst stations,
except higher concentration of Zinc was recorded at Impact stations (Table B3 of Annex
B; Figure 7 of Annex C).
For nutrients, concentrations of Total Inorganic Nitrogen
(TIN) at all stations in July 2016 exceeded the WQO (0.5 mg/L) (Table B3 of Annex
B; Figure 8 of Annex C). It should be
noted that due to effect of Pearl River, the North Western WCZ has historically
experienced higher levels of TIN ().
Since TIN concentrations were recorded to be similar amongst all
stations, the exceedances of TIN WQO at all 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 (Table B3 of Annex
B; Figure 8 of Annex C). Levels of
5-day Biochemical Oxygen Demand (BOD5) appear to be higher at
station in July 2016 (Table
B3 of Annex B; Figure 9
of Annex C).
Concentrations of SS were higher than the WQO (11.1 mg/L for
wet season) at Impact and Reference stations. However, concentrations of SS complied with
the Action and Limit Levels at all stations in July 2016 (Table B3 of Annex
B; Figure 10 of Annex C).
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
2016. Detailed statistical analysis will be
presented in the Quarterly Report to investigate any spatial and temporal
trends of potential concern.
Water Column Profiling of ESC CMP Vd – July 2016
Water Column Profiling was undertaken on 5 July 2016. The monitoring results have been assessed for
compliance with the WQOs (see Section 1.5.3 for details). Levels of DO and
Turbidity were also assessed for compliance with the Action and Limit Levels
(see Table B1 of Annex B for details).
of results for July 2016 indicated that levels of Salinity, DO and pH
complied with the WQOs at both Downstream and
Upstream stations (Table B4 of Annex B). In addition, DO
and Turbidity at all stations complied with the Action and Limit Levels (Table B4 of Annex B).
Laboratory Measurements for Suspended Solids (SS)
of results for July 2016 indicated that the SS levels were higher than the WQO
at both Upstream and Downstream stations.
Both Upstream and Downstream stations complied with the Action and Limit
Levels (Table B4 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 period.
Pit Specific Sediment Chemistry of ESC CMP
Vd – July 2016
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 in July 2016.
The concentrations of most inorganic contaminants
were lower than the Lower Chemical Exceedance
Level (LCEL) at all stations, except Arsenic (Figures
11 and 12 of Annex C). In July 2016, concentration
of Arsenic at Active Pit station ESC-NPAB exceeded
the LCEL (Figure 11 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 ().
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.
For organic contaminants,
the concentrations of Total Organic Carbon (TOC) were similar amongst the stations in July 2016 (Figure
13 of Annex C). In July 2016, Tributyltin
(TBT) concentrations were higher at Active Pit station ESC-NPAB (Figure
14 of Annex C). Low and High Molecular Weight Polycyclic
Aromatic Hydrocarbons (PAHs), Total Polychlorinated
Biphenyls (PCBs), Total dichlorodiphenyltrichloroethane (DDT) and 4,4’-dichlorodiphenyldichloroethylene
(DDE) concentrations were below the limit of reporting at all stations in July 2016.
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 2016. Statistical
analysis will be undertaken and presented in the quarterly report to
investigate whether there are any unacceptable impacts in the area caused by
the contaminated mud disposal.
Scheduled for the Next Month
The following monitoring activities will be conducted in the next
monthly period of August 2016 for ESC CMPs:
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 Test of ESC CMPs;
Studies of ESC CMP IV; and
Demersal Trawling of ESC CMPs.
The following monitoring activities will be conducted in the next
monthly period of August 2016 for SB CMPs:
Water Quality Monitoring During Capping of SB CMPs; and
Studies of SB CMPs.
sampling schedule is presented in Annex A.
summary of the Study programme is presented in