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
18TH MONTHLY PROGRESS REPORT FOR February
Since early 1990s, contaminated sediment ()
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) ()
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 East of Sha Chau (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 ()
to be implemented for the CMPs.
The present EM&A programme
undertaken under Agreement
No. CE 23/2012 (EP) covers the dredging,
disposal and capping operations of the SB CMPs as well as CMPs
at East of Sha Chau (ESC). In February 2014, the following works were
being undertaken at the CMPs:
was being undertaken at ESC CMP IVc and CMP Va;
Disposal of contaminated
mud was taking place at SB CMP 1; and
operations were taking place at SB CMP 2.
Monthly Progress Report covers the EM&A activities for
the reporting month of February 2014.
Details of Sampling and
Laboratory Testing Activities
Water Quality Monitoring during Capping Operations at
ESC CMPs was undertaken on 14 February 2014.
The following monitoring
activities have been undertaken for SB CMPs in
Impact Water Quality Monitoring during Dredging
Operations was undertaken for CMP 2 three
times per week on 4, 6, 8, 11, 13, 15, 18, 20, 22, 25, and 27 February
Quality Monitoring was undertaken for CMP 1 on 5, 7, 10, 12, 14, 17, 19, 21, 24, 26 and 28
Demersal Trawling for CMP 1 was undertaken out
on 11 and 12 February 2014;
Pit Specific Sediment Chemistry was undertaken for CMP 1 on 18 February 2014;
Sediment Chemistry was undertaken on
20 and 22 February 2014; and
Water Column Profiling for CMP 1 was undertaken on 21 February 2014.
No outstanding sampling
February 2014. The following
laboratory analyses were still in progress during the preparation of this
monthly report and hence were not presented in this monthly report:
Laboratory analyses of sediment samples collected for Pit Specific Sediment
Chemistry of CMP 1
in December 2013, January and February 2014;
Laboratory analyses of sediment samples collected for Cumulative
Impact Sediment Chemistry of CMP 1
in February 2014;
Laboratory analyses of water samples
collected for Routine Water Quality Monitoring for CMP 1 from 17 to
29 January 2014; and
Laboratory analyses of Suspended
Solids (SS) samples collected for Water Quality Monitoring during Dredging
Operations of CMP 2 on 27 February 2014.
A summary of field activities
conducted are presented in Annex
discussion of the monitoring results of the following activities is presented
in this 18th Monthly Progress Report:
Impact Water Quality Monitoring during Dredging Operations of CMP 2 conducted
from 10 January to 25 February 2014;
Routine Water Quality Monitoring of CMP 1 undertaken from 5 to 28
Water Column Profiling of CMP 1 conducted on 21 February 2014; and
Cumulative Impact Sediment Chemistry conducted in December 2013.
Quality Monitoring during Dredging Operations of CMP 2 –10 January to 25
Monitoring data collected for CMP 2 from 10
January to 25 February 2014 are presented in this monthly report. Detailed discussion will be presented in the
corresponding Quarterly Report.
Impact Water Quality Monitoring during Dredging
Operations of CMP 2 was conducted three times per week from 10 January to
25 February 2014. On each survey day,
sampling was conducted during both mid-ebb and mid-flood tides at two Reference
(Upstream) stations upstream and five Impact (Downstream) stations downstream
of the dredging operations at CMP 2.
Monitoring was also conducted at five Sensitive Receiver Stations
situated in Ma Wan, Shum Shui Kok,
Tai Mo To and Tai Ho Bay. A total of
twelve stations were monitored and locations of the sampling stations are shown
in Figure 1.1.
Monitoring results from 10 January
to 25 February 2014 are presented in Table C1 of Annex C. Daily dredging volume in January and February
2014 is reported in Annex
D. Levels of Dissolved
Oxygen (DO), Turbidity and SS generally complied with the Action and Limit
Levels (see Table C2
of Annex C for
details) set in the Baseline Monitoring Report (),
except for the following occasions of exceedances
shown in Table 1.1
Table 1.1 Details of Exceedances
Recorded at CMP 2 in January and February 2014
10 January 2014
13 January 2014
17 January 2014
24 January 2014
was recorded at station DS1 only on 13 January 2014 (mid-flood). Since station DS1 was located at the boundary
of the works area, the sole exceedance at this
station did not appear to indicate any unacceptable water quality impacts
outside the works area of the Project.
On 24 January 2014, SS exceedances were
recorded at stations DS2 and DS3 but not station DS1 which is located closer to
the dredging operations. As such, the exceedances recorded are unlikely to be caused by the
dredging operations at CMP 2. The SS exceedances recorded on 10 and 17 January 2014
(mid-flood) at stations DS1 and DS2 did not appear to indicate any trend of
increasing SS towards the dredging operations with higher SS concentration
recorded at DS2. Overall, it did not
appear that the SS exceedances were caused by the dredging
operations at CMP 2.
on 17 January 2014 (mid-flood) was recorded at station DS2 which were was
further away from the works area when compared to station DS1 at which the
level of Turbidity did not exceed the Action and Limit Levels during the same
tidal period on the same day. As such,
these recorded exceedances are not likely to be
caused by the dredging works at CMP 2.
It should be noted that high levels
of Turbidity and SS were occasionally recorded during baseline monitoring which
are considered to be sporadic events and characteristic of water quality in
this area of Hong Kong (baseline monitoring
data are summarised in Table C3 of Annex C). Therefore, the Action and Limit Level exceedances may be caused by natural background variation
in water quality of the area.
Overall, the results indicated that
the dredging operations at CMP 2 did not appear to cause any unacceptable
deterioration in water quality during this reporting period. Therefore, no further mitigation measures,
except for those recommended in the Environmental Permit (EP-427/2011/A),
are considered necessary for the dredging operations.
Quality Monitoring of
SB CMP 1 – January 2014
Monitoring results from 3 to 15
January 2014 were presented in 17th Monthly Progress Report. Daily monitoring
results for 18 to 29 January 2014 are shown in Tables C4 and C5 of Annex C . Monthly averaged and daily monitoring results
for January 2014 are presented with graphical presentation in Figure 1-Figure
20 of Annex B.
The monitoring results
for the Routine Water Quality Monitoring
conducted for January 2014 in the dry season have been assessed for compliance
with the Water Quality Objectives (WQOs) set by
consists of a review of the EPD routine water quality monitoring data for the
dry season period (November to March) of 2003-2012 from stations in the Northwestern Water Control Zone, where the CMPs are located.
For Salinity, the averaged value obtained from the Reference stations
was used for the basis as the WQO. Levels
of DO, Turbidity and SS were also assessed for compliance with the Action and
Limit Levels (see Table C2 of Annex C
Monthly averaged and daily
monitoring results for February 2014 will be presented with graphical
presentation in the next monthly report when all monitoring results for
February 2014 are received.
Locations of monitoring stations
were presented in Figure 1.2 and Figure 1.3.
results indicated that for all the stations (Impact, Intermediate, Reference
and Water Sensitive Receiver stations), both daily and monthly average levels
of pH, DO and Salinity complied with the WQOs in
January 2014 (Figure 1, 2, 4, 12, 15, and 16 of Annex B).
In January 2014, daily and
monthly average levels of DO and Turbidity at all the stations complied with
the Action and Limit Levels (Tables C5 and C7 of Annex C).
In January, monthly average
concentrations of Nickel and Zinc were slightly higher at Tai Ho Bay Station 2 and Tai Ho
Bay Station 1, respectively (Figure 6 and 7 of Annex B). Monthly average concentrations of the other metals were similar amongst
stations (Figures 6-7 of Annex B). Monthly average levels of 5-day Biochemical
Oxygen Demand (BOD5), Ammoniacal-Nitrogen
(NH3-N) and Total Inorganic Nitrogen (TIN) in January 2014 were similar amongst station
8 and 9 of Annex B). The monthly
average concentration of TIN did not show any exceedance
with the WQO in January 2014 (Figure 9 of Annex B).
Analyses of January 2014 results
indicated that daily concentrations of Cadmium, Mercury and Silver were below
their limits of reporting at all the stations (Figure 17, 19
and 23 of Annex B). The daily concentrations of Arsenic,
Chromium, Copper, Lead, Nickel and Zinc indicated variations over
time at all the stations throughout January 2014.
Daily recorded levels of TIN, BOD5
and NH3-N were observed to fluctuate over time
throughout January 2014 (Figure 26-28 of Annex B). Compliance with TIN WQO (0.50 mg/L) was
observed at all the stations in the monitoring period except for the measurement
at Tai Ho Bay station 1(THB1) on 9 January 2014. This only exceedance
of TIN WQO did not appear to provide any evidence of unacceptable water quality
impacts due to the mud disposal activities.
Daily levels of SS
complied with the Action and Limit Levels set in the EM&A Manual
and occasionally exceeded SS WQO (14.4 mg/L for dry
season) (Figure 29 of Annex
B) in January 2014.
The monthly average levels of SS compiled with the WQO at
all stations (Figure 10 of Annex
B). These occasional exceedances
recorded for daily SS levels are thus not likely to be caused by mud disposal
works, but sporadic events and characteristic of water quality in
this area of Hong Kong.
Overall, results of the Routine Water
Quality Monitoring indicated that the disposal operation at CMP 1 did not
appear to cause any unacceptable deterioration in water quality in January
From the results of the Routine Water
Quality Monitoring conducted in October 2013, November 2013 and January
2014 for CMP 1, there did not appear to be any unacceptable deterioration in
water quality in all of the sampling events which were conducted three times a
week during the monitoring period. In
accordance with the EM&A Manual, it is recommended to adjust the sampling
frequency to eight (8) times per year which is the same as the frequency of Routine Water
Quality Monitoring for CMP V. It
is anticipated that this adjusted sampling frequency is adequate for tracking
the potential change in contaminant concentrations in seawater which may take a
long time to appear while at the same time address the potential seasonal
difference in seawater quality.
Profiling of CMP 1 –
Water Column Profiling was
undertaken at a total of two sampling stations (Upstream and Downstream
stations) on 21 February 2014. The
water quality monitoring results have been assessed for compliance with the WQOs (Table C8 of Annex C). The monitoring results were
also compared with the Action and Limit Levels set
in the Baseline
Analyses of results for February
2014 indicated that levels of Salinity, pH and DO complied with the WQOs at both Upstream and Downstream stations (Table C8 of Annex C). DO and Turbidity complied with the Action and
Laboratory Measurements for Suspended Solids (SS)
Analyses of data obtained on 21
February 2014 indicated that the SS levels at Downstream and Upstream stations
complied with the WQO (Table C8 of Annex C).
In addition, SS levels at all the stations complied with the Action and
Overall, the monitoring results
indicated that the mud disposal operation at CMP 1 did not appear to cause any
deterioration in water quality during this reporting period.
Sediment Chemistry of CMP 1 – December 2013
Monitoring locations for Cumulative
Impact Sediment Chemistry for CMP 1
are shown in Figure 1.4. A total of eleven (11) monitoring stations
were sampled in December
Analyses of results for the Cumulative Impact
Sediment Chemistry Monitoring indicated that the concentrations
of all metals, except Arsenic, were below the Lower Chemical Exceedance Level (LCEL) in December
2013 (Figures 30 and 31 of
Annex B). Concentrations of Arsenic
in sediments from all stations exceeded the LCEL, except for Near Field station
SB-RNB and Mid Field station SB-RMB.
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
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 CMP 1 but rather as a result of naturally occurring
For organic contaminants, concentration of Total Organic
Carbon (TOC) at Tai Ho Bai Station 2 (THB2) was
recorded to be higher than other stations (Figure 32 of Annex B). Concentrations of Tributyltin
(TBT) were recorded to be higher at Near-field station SB-RNB and Ma Wan
station (Figure 33 of Annex B). Total Dichloro-diphenyl-trichloroethane (DDT) and 4,4’-Dichloro-diphenyl-dichloroethylene (4,4’-DDE) were recorded below
the limit of detection at most stations with no apparent spatial trend (Figure 34 of Annex B). Concentrations of Total Polychlorinated
Biphenyls (PCBs) as well as Low and High Molecular Weight Polycyclic Aromatic
Hydrocarbons (Low and High MW PAHs) were recorded
below the limit of reporting at all the stations.
Overall, there is no evidence indicating any
unacceptable environmental impacts to sediment quality as a result of the
contaminated mud disposal operations at CMP 1 during this monthly period.
Activities Scheduled for the
The following monitoring activities
will be conducted in the next monthly period of March 2014 for SB CMPs:
Impact Water Quality Monitoring during Dredging
Operations of CMP 2;
Pit Specific Sediment Chemistry of CMP 1; and
Water Column Profiling of CMP 1.
The sampling schedule is presented
in Annex A.
A summary of the Study programme is
presented in Annex E.