Agreement No.
CE 23/2012 (EP)
Environmental Monitoring and Audit
for Contaminated Mud Pits at the South of The Brothers
and at
12TH
MONTHLY PROGRESS REPORT FOR AUGUST 2013
1.1
Background
1.1.1
Since early 1990s, contaminated
sediment ([1])
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) ([2])
facility at the South of The Brothers (SB CMPs) (hereafter referred to as “the Project”) which had
been under consideration for a number of years.
1.1.2
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) ([3]). 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).
1.1.3
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 ([4]). 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.
1.1.4
Environmental Permits (EPs) (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 ([5])([6])
is required to be implemented for the CMPs.
1.1.5
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 August 2013,
the following works were being undertaken at the CMPs:
·
Capping was being
undertaken at CMP IVc;
·
Disposal of contaminated
mud was taking place at CMP Va until 26 August 2013;
·
Disposal of contaminated
mud was taking place at SB CMP 1 since 27 August 2013;
·
Dredging operations were
taking place at SB CMP 1 until 13 August 2013; and
·
Dredging operations were
taking place at SB CMP 2 since 15 August 2013.
1.2
Reporting Period
1.2.1
This Monthly Progress Report covers
the EM&A activities for the reporting month of
August 2013.
1.3
Details of Sampling and
Laboratory Testing Activities
1.3.1
The following monitoring activities have
been undertaken for CMP V in August 2013:
· Pit Specific Sediment Chemistry was conducted for CMP Va
on 22 August 2013;
· Water Column Profiling was scheduled to be undertaken on 1 August
2013. However, there was no dumping
activity at CMP Va while the monitoring team was
on-site. As such, in-situ measurements and water sampling
were not undertaken for Water Column
Profiling in August 2013;
· Routine Water Quality Monitoring was conducted for CMP Va
on 24 August 2013;
· Demersal Trawling was conducted for
CMP Va on 19 and 20 August 2013;
· Sediment Toxicity Test was
conducted for CMP Va on 20 August 2013; and
· Cumulative Impact Sediment
Chemistry was conducted for CMP Va on 29 August 2013;
1.3.2
Impact Water Quality Monitoring during Dredging
Operations was conducted three times per week (ie 31 July; 3, 5, 7, 9, and 12 August 2013 for CMP 1 and
16, 19, 21, 23, 26, 28 and 30 August 2013 for CMP 2) in this reporting month in
accordance with the EM&A Manual.
It should be noted that the Impact Water Quality Monitoring during Dredging
Operations was not conducted on 1 and 14 August 2013 due to
adverse weather during which Typhoon signal No. 3 and Typhoon signal No. 8 were
hoisted, respectively. Demersal Trawling for CMP 1 was conducted on 21 and 22
August 2013.
1.4
Details of Outstanding Sampling and/or Analysis
1.4.1
No outstanding
sampling remained for August
2013. Laboratory analyses of Pit Specific Sediment Chemistry of CMP Va conducted in August 2013
were yet to be completed. A summary of field activities conducted
are presented in Annex A.
1.5
Brief Discussion of the Monitoring Results for CMP V
1.5.1
Table 1.1 summarises the monitoring
results that are presented in the current monthly report. Brief discussion of the monitoring results is presented in
this section. Detailed discussion
will be presented in the corresponding Quarterly
Report.
|
Monitoring activities |
Date of Monitoring |
Monitoring
results presented in this report? |
|
Pit Specific Sediment Chemistry Monitoring for CMP Va |
6 June 2013
22 August 2013 |
Yes. Yes. No. Laboratory analysis yet to be
completed during preparation of this monthly report. |
|
Cumulative Impact Sediment Chemistry Monitoring for CMP Va |
18 June 2013 29 August 2013 |
Yes. No. Laboratory analysis yet to be
completed during preparation of this monthly report. |
|
Sediment
Toxicity Test |
20 August 2013 |
No. It will be presented in the Quarterly
Report. |
|
Routine Water Quality Monitoring for CMP Va |
24 August 2013 |
Yes. |
|
|
|
|
|
Water Column Profiling for CMP Va |
1 August 2013 |
No. In-situ
measurements and water sampling were not undertaken as there was no
dumping activity on the monitoring day. |
|
Demersal Trawling |
19 and 20 August 2013 |
No. It will be presented in the Quarterly
Report. |
Table 1.1 Monitoring
activities from June to August 2013 for CMP V
1.5.2
Pit Specific
Sediment Chemistry of CMP Va
– June
and July 2013
1.5.3
Monitoring
locations for Pit Specific Sediment Chemistry for CMP Va
are shown in Figure 1.1. A total of six monitoring stations were
sampled in June and July 2013. It
is observed that the variations of metal concentrations at Active Pit Stations NPDA and NPDB
were much larger (ie greater standard deviation) when
compared to other stations (Figures 1, 2, 6, and 7 of Annex B).
1.5.4
Cadmium,
Chromium, Copper, Lead, Zinc and Nickel complied with the Lower Chemical Exceedance
Level (LCEL) at all stations in June and July 2013 (Figures
1, 2, 6, and 7 of Annex B).
Concentrations of Arsenic exceeded the LCEL at Active Pit station NPDB,
Pit Edge station NEDB and Near Pit stations NNDA and NNDB (Figures 1 of Annex B) in June and exceeded the LCEL at Active Pit station
NPDB, Pit Edge stations NEDA and NEDB and Near Pit station NNDA in July 2013 (Figures 6 of Annex B).
Concentrations of Mercury exceeded LCEL
at Active Pit station
NPDA and concentrations of Silver exceeded LCEL at Active Pit
station NPDB in June 2013 (Figures 2 of Annex B).
1.5.5
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 ([7]). It is presumed that the natural concentrations of Arsenic are similar in
onshore and offshore sediments ([8]), and relatively high Arsenic levels may thus occur
throughout Hong Kong . Therefore, the exceedances
of the LCEL for Arsenic are unlikely to be caused by the disposal operations at
CMP Va but rather as a result of naturally occurring
deposits.
1.5.6
In
addition, the Active Pit stations NPDA and
NPDB are located within CMP Va which was receiving contaminated mud during the
reporting period. As such, the exceedances of LCEL for Mercury
and Silver which were recorded at the two stations only are not
considered as indicating any dispersal of contaminated mud from CMP Va.
1.5.7
Total
Organic Carbon (TOC) concentration was similar amongst all stations in June and
July 2013 (Figure 3 and 8 of Annex
B). Tributyltin
(TBT) concentration was found to be higher at Active Pit stations NPDA and NPDB (Figure 4 of Annex B) in June 2013 and at Active Pit
station NPDA in July 2013 (Figure 9 of Annex B).
1.5.8
Low
Molecular Weigh Polycyclic Aromatics Hydrocarbons (Low MW PAHs)
and High Molecular Weight Polycyclic Aromatics Hydrocarbons (High MW PAHs) concentrations were recorded above the limit of reporting
at Active Pit stations NPDA and NPDB in June and July 2013 (Figure 5 and 10 of Annex
B). Low and Hight
MW PAHs were also observed to exceed LCEL at Active
Pit station NPDA in June 2013.
1.5.9
Total
Dichloro-diphenyl-trichloroethane (DDT) and
4,4’-Dichloro-diphenyl-dichloroethylene (4,4’-DDE) were below the limit of
reporting at all stations in June and July except for the 4,4’-DDE level at
Active Pit station NPDB in July 2013.
Total Polychlorinated Biphenyls (PCBs) were recorded above the limit of
reporting in July at Active Pit Station NPDA, but well below LCEL.
1.5.10
As explained in Section 1.5.6, Active Pit stations NPDA and NPDB are located within CMP Va which was receiving contaminated mud during the
reporting period. Therefore, the
higher concentrations of contaminants (including metals and organic
contaminants) recorded at the two stations only are not considered as
indicating any dispersal of contaminated mud from CMP Va. Nevertheless, detailed analysis will be
presented in the Quarterly Report to reveal any trend of increasing
sediment contaminant concentrations towards CMP Va.
1.5.11
Overall,
there is no evidence indicating any unacceptable environmental impacts to
sediment quality as a result of the contaminated mud disposal operations at CMP
Va during this monthly period.
1.5.12
Routine Water Quality Monitoring for CMP Va – August 2013
1.5.13
The
results for the Routine Water Quality Monitoring conducted during August 2013 in the
wet season 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 1999-2010 from stations in the Northwestern Water Control Zone, where the CMPs are located.
For Salinity, the average value obtained from the Upstream Station was
used for the basis as the WQO. In-situ monitoring and laboratory
results are shown in Tables 1.2 and 1.3, respectively, with graphical presentation provided
in Annex
B. Monitoring was undertaken at a total of
10 stations in the reporting month (see Figure 1.2).
In-situ Measurements
1.5.14
Analysis of results for August 2013
indicated that for all the stations (Impact, Intermediate, Reference and Ma
Wan), levels of pH and DO
complied with the WQOs (Figures
11 and 12 of Annex B). Levels of
Salinity were recorded exceeding the WQO at Impact Stations and Ma Wan Station (Figure
14 of Annex B). The higher salinity recorded at Ma Wan
station is likely to be caused by its greater separation distance from the Pearl River mouth, which is a key source of freshwater
inputs in the area, when compared to the Reference stations. The Salinity levels exceeding WQO was
only recorded at the Impact Stations which are located close to the working
area for mud disposal and the exceedance is rather
marginal. There is no evidence indicating any
unacceptable environmental impacts to water quality as a result of the
contaminated mud disposal operations at CMP Va during
this monthly period.
1.5.15
Levels of
Turbidity within the reporting month complied with the Action and Limit Levels
set in the EM&A Manual ([9])
(Figures
15 of Annex B). All in-situ water quality measurements showed relatively minor
variations amongst Impact, Intermediate and Reference stations (Figures 11-15 of Annex B).
Laboratory
Measurements
1.5.16
Analyses
of August 2013 results indicate that concentrations of Mercury and
Silver were below their limit of reporting at all stations. Arsenic was recorded at Intermediate Station INF1 and
Cadmium was detected at Ma Wan station.
Chromium, Copper, Lead, Nickel
and Zinc were detected in samples from all stations. Concentrations of Chromium, Copper, Lead, Nickel and Zinc were slightly higher at Ma Wan station while the concentrations of Arsenic were similar
amongst stations (Figures 16 and 17 of Annex B). Levels
of 5-day Biochemical Oxygen Demand (BOD5), Total Inorganic Nitrogen
(TIN) and Ammoniacal-Nitrogen (NH3-N) were
similar amongst all stations (Figures 18 and 19 of Annex B).
1.5.17
Exceedances of
Suspended Solids (SS) WQO (12.74 mg/L for wet season) were recorded (Figure 20 of Annex B). However, the exceedance
of WQO was recorded at Reference stations and Intermediate stations rather than
the Impact stations. Hence, it is
considered that the exceedance of WQO at Reference
and Intermediate stations are unlikely to be caused by mud disposal
operations. Concentrations of SS
complied with the Action and Limit Levels at all stations during the reporting
month.
1.5.18
Overall,
the results indicated that the disposal operation at CMP Va
did not appear to cause any unacceptable deterioration in water quality during
this reporting period.
Table 1.2 In-situ
Monitoring Results for Routine Water Quality Monitoring of CMP Va in August 2013
|
Stations |
Temp |
Salinity |
Turbidity |
pH |
Dissolved Oxygen |
|
|
|
(°C) |
|
(NTU) |
|
(%) |
(mg L-1) |
|
RFF (Reference) |
27.53 |
13.40 |
14.74 |
7.52 |
68.83 |
5.05 |
|
IPF (Impact) |
27.46 |
15.03 |
9.35 |
7.55 |
67.22 |
4.89 |
|
INF (Intermediate) |
27.55 |
14.34 |
14.96 |
7.53 |
67.95 |
4.95 |
|
Ma Wan Station |
26.96 |
22.39 |
8.23 |
7.59 |
64.22 |
4.52 |
|
WQO |
N/A |
12.06-14.73# |
N/A |
6.5-8.5 |
N/A |
>4 |
|
Note: #Not exceeding 10% of natural
ambient level which is the result obtained from the Reference Station. |
||||||
Table 1.3 Laboratory
Results for Routine Water Quality Monitoring of CMP Va in August 2013
|
Stations |
As (µg/L) |
Ag (µg/L) |
Cd (µg/L) |
Cr (µg/L) |
Cu (µg/L) |
Hg (µg/L) |
Pb (µg/L) |
Ni (µg/L) |
Zn (µg/L) |
NH3-N (mg/L) |
TIN (mg/L) |
BOD5 (mg/L) |
SS (mg/L) |
||
|
RFF |
<LOR |
<LOR |
<LOR |
1.65 |
18.13 |
<LOR |
3.58 |
4.50 |
15.63 |
0.05 |
1.39 |
0.61 |
13.75 |
||
|
IPF |
<LOR |
<LOR |
<LOR |
0.85 |
19.42 |
<LOR |
2.31 |
4.00 |
11.38 |
0.05 |
1.33 |
0.59 |
8.33 |
||
|
INF |
1.29 |
<LOR |
<LOR |
1.19 |
21.92 |
<LOR |
2.71 |
4.33 |
12.96 |
0.05 |
1.37 |
0.58 |
16.50 |
||
|
Ma Wan Station |
<LOR |
<LOR |
0.19 |
2.38 |
23.88 |
<LOR |
3.75 |
6.13 |
34.88 |
0.05 |
0.98 |
0.56 |
10.50 |
||
|
|
WQO of SS: 12.74 mg/L |
||||||||||||||
|
Note: LOR = Limit Of Reporting |
|
||||||||||||||
1.5.19
Cumulative Impact Sediment Chemistry for CMP Va – June 2013
1.5.20
Monitoring
locations for Cumulative Impact Sediment Chemistry for CMP Va
are shown in Figure 1.3. A total of nine monitoring stations were
being sampled.
1.5.21
Analyses of results for the
Cumulative Impact Sediment Chemistry Monitoring indicated that the
concentrations of all metals, except Arsenic, were below the LCEL
in June 2013 (Figures 21 and 22 of Annex B). Concentrations of Arsenic in sediments from all stations,
except for Near Field station RNB, exceeded the LCEL. As discussed in Section
1.5.5 above, relatively
high natural levels of Arsenic are present in Hong Kong ’s
marine sediments and hence the slight exceedances of
the LCEL for the Arsenic do not necessarily indicate any adverse impacts to
sediment quality caused by disposal operation at CMP Va.
1.5.22
The concentration of TOC shows variation
amongst stations (Figure 23 of Annex B). TBTs were
recorded in sediment samples from all stations and Capped Pit station RCA and
Ma Wan station were recorded with a higher concentration (Figure 24
of Annex B). Concentrations of Total PCBs,
Low and
High MW PAHs
were below the limit of detection at all the stations. Concentrations of total DDT were recorded
below the limit of detection at all the staions
except Near Field station RNA, Mid-field station RMB, and Far Field station
RFA. Concentrations of 4-4’ DDE
were recorded below the limit of detection at all the staions
except Near Field stations RNA and RNB, Mid-field station RMB and Ma Wan
station .
1.5.23
Overall,
there is no evidence indicating any unacceptable environmental impacts to
sediment quality as a result of the contaminated mud disposal operations at CMP
Va during this monthly period.
1.6
Brief Discussion of the Monitoring Results for SB CMPs
1.6.1
Monitoring data collected for SB CMPs from 31
July to 30 August
2013 are presented in this monthly report. Detailed discussion will be presented in
the corresponding Quarterly Report.
1.6.2
Impact Water
Quality Monitoring during Dredging Operations of CMP 1 and CMP 2 – 31 July to 30 August 2013
1.6.3
Impact Water Quality Monitoring during Dredging
Operations of CMP 1 (ie from 31 July to
12 August 2013) and CMP2 (ie from 16 to 30
August 2013) was conducted three times per week for a total of thirteen (13)
sampling days. 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 1 and CMP 2. Monitoring was also conducted at five
Sensitive Receiver Stations (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 1.4.
1.6.4
Monitoring results from 31 July to 30 August 2013 are presented in Table C1 of Annex C. It should be noted that samplings
during mid-ebb tide of 3 August 2013
and during both mid-ebb and mid-flood
tides of 1 and 14 August
2013 were not carried out due to adverse weather. Sampling at THB2 was also cancelled
during mid-ebb tide on 30 August 2013 due to adverse weather. Levels of DO, Turbidity and SS generally
complied with the Action and Limit Levels (see Table C2 for details) set in the Baseline Monitoring Report ([10]),
except for the following occasions of exceedances
shown in Table 1.4 and Table 1.5
below.
Table 1.4 Details of exceedances recorded at CMP 1 in August 2013
|
Date |
Tide |
Parameter |
Station |
Type |
|
3 August 2013 |
Mid-Flood |
SS |
DS2 |
Action |
|
3 August 2013 |
Mid-Flood |
SS |
DS3 |
Action |
|
5 August 2013 |
Mid-Flood |
SS |
WSR46 |
Action |
|
7 August 2013 |
Mid-Ebb |
Turbidity |
WSR46 |
Action |
|
7 August 2013 |
Mid-Ebb |
SS |
WSR46 |
Action |
|
7 August 2013 |
Mid-Flood |
Turbidity |
DS3 |
Action |
|
7 August 2013 |
Mid-Flood |
Turbidity |
WSR46 |
Action |
|
7 August 2013 |
Mid-Flood |
SS |
DS2 |
Action |
|
7 August 2013 |
Mid-Flood |
SS |
DS3 |
Limit |
|
7 August 2013 |
Mid-Flood |
SS |
WSR46 |
Action |
Table 1.5 Details
of exceedances recorded at CMP 2 in August 2013
|
Date |
Tide |
Parameter |
Station |
Type |
|
19 August 2013 |
Mid-Flood |
SS |
WSR45C |
Action |
|
19 August 2013 |
Mid-Flood |
SS |
WSR46 |
Action |
|
19 August 2013 |
Mid-Flood |
Turbidity |
WSR46 |
Action |
|
21 August 2013 |
Mid-Ebb |
DO (Surface + Mid-depth) |
DS3 |
Limit |
|
21 August 2013 |
Mid-Ebb |
DO (Surface + Mid-depth) |
DS4 |
Limit |
|
21 August 2013 |
Mid-Flood |
Turbidity |
WSR46 |
Action |
|
21 August 2013 |
Mid-Flood |
SS |
WSR45C |
Action |
|
23 August 2013 |
Mid-Flood |
Turbidity |
WSR45C |
Action |
|
23 August 2013 |
Mid-Flood |
Turbidity |
WSR46 |
Action |
|
23 August 2013 |
Mid-Flood |
SS |
WSR46 |
Action |
|
26 August 2013 |
Mid-Flood |
SS |
WSR45C |
Action |
|
26 August 2013 |
Mid-Flood |
SS |
WSR46 |
Action |
|
31 August 2013 |
Mid-Flood |
SS |
DS3 |
Action |