Contents
1.1 Background
1.2 Purpose
of the Report
1.3 Structure
of the Report
2 Baseline Water quality
monitoring Methodology
2.1 Monitoring Locations
2.2 Monitoring Parameters
and Frequency
2.3 Monitoring Equipment
and Methodology
3 Baseline
Water Quality Monitoring Results
3.1 Introduction
3.2 Water Quality
Monitoring Results
LIST OF ANNEXES
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Annex A |
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Annex B |
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Annex C |
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Annex D |
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EXECUTIVE
SUMMARY
The
Hong Kong Civil Engineering and Development Department (CEDD) have undertaken
baseline water quality monitoring prior to the commencement of dredging works
for Contaminated Mud Pits (CMP 1 and CMP 2) at the South of The Brothers.
This
Baseline Monitoring Report has been prepared in compliance with the
Environmental Permit (EP-427/2011/A) and the Environmental Monitoring and Audit
Manual for the Disposal of Contaminated Sediment ¡V Dredging, Management and
Capping of Contaminated Sediment Disposal Facility at the South of The Brothers.
Baseline
water quality monitoring was conducted between 26 July and 23 August 2012 at eighteen
designated monitoring stations established for the Project. The monitoring was carried out 3 days
per week, at mid-flood and mid-ebb tides, at three depths (surface, middle and
bottom), for 5 weeks prior to the commencement of dredging works. No major activities were noted during
baseline monitoring. Water quality
monitoring results are, therefore, representative of the baseline conditions
for the Project.
Results
have been used to determine Action and Limit Levels for the dissolved oxygen, suspended
solids and turbidity for impact monitoring to be conducted during dredging,
backfilling and capping activities for the Project and listed in Table I. These Action and Limit Levels
will be used for impact monitoring during dredging, backfilling and capping
activities to check if there are exceedances of water
quality due to the Project.
Table
I Proposed
Action and Limit Levels of Water Quality for Dredging, Backfilling and Capping
Activities
Parameter |
Action
Level |
Limit
Level |
Dissolved
Oxygen (DO) (1) |
Surface and Mid-depth
(2) |
Surface and Mid-depth
(2) |
|
The average of the
impact, WSR
45C and WSR 46 station readings are <
5%-ile of baseline data for surface and middle
layer = 4.32 mg L-1 and Significantly less than
the reference stations mean DO (at the same tide of the same day) |
The average of the
impact, WSR
45C and WSR 46 station readings are
< 4 mg L-1 and Significantly less than
the reference stations mean DO (at the same tide of the same day) |
|
|
|
|
Bottom |
Bottom |
|
The average of the
impact, WSR
45C and WSR 46 station readings are <
5%-ile of baseline data for bottom layers = 3.12 mg
L-1 and Significantly less than
the reference stations mean DO (at the same tide of the same day) |
The average of the impact
station, WSR
45C and WSR 46 readings are < 2 mg L-1 and Significantly less than
the reference stations mean DO (at the same tide of the same day) |
|
|
|
Depth-averaged
Suspended Solids (SS) (3) (4) |
The average of the
impact, WSR
45C and WSR 46 station readings are
> 95%-ile of baseline data for depth average = 21.60 mg L-1 and |
The average of the
impact, WSR
45C and WSR 46 station readings are
> 99%-ile of baseline data for depth average = 40.10 mg L-1 and |
|
120% of control station's SS at the same tide of
the same day |
130% of control station's SS at the same tide of
the same day |
|
|
|
Depth-averaged
Turbidity (Tby) (3) (4) |
The average of the
impact, WSR
45C and WSR 46 station readings are
> 95%-ile of baseline data = 25.04 NTU and |
The average of the
impact, WSR
45C and WSR 46 station readings are
> 99%-ile of baseline data = 56.30 NTU and |
|
120% of control station's Tby
at the same tide of the same day |
130% of control station's Tby
at the same tide of the same day |
|
|
|
Notes: (1)
For DO, non-compliance of the water quality
limits occurs when monitoring result is lower than the limits. (2)
The Action and Limit Levels for DO for
Surface & Middle layers were calculated from the combined pool of
baseline surface layer data and baseline middle layer data. (3)
¡§Depth-averaged¡¨ is calculated by taking the
arithmetic means of reading of all three depths. (4)
For turbidity and SS, non-compliance of the
water quality limits occurs when monitoring result is higher than the limits. |
The
Hong Kong Civil Engineering and
Development Department (CEDD) have commissioned ERM-Hong Kong, Ltd (ERM) supported by Mr Peter Whiteside
(Independent Consultant), Halcrow China Ltd (HCL) and Professor Wen-Xiong Wang (Independent Auditor) of the Hong Kong
University of Science and Technology (HKUST), to undertake the Environmental Monitoring and Audit for
Contaminated Mud Pits to the South of The Brothers and at East Sha Chau (2012-2017)
¡V Investigation (hereafter referred as ¡§the Study¡¨). This Study, awarded
under Agreement No. CE 23/2012 (EP), commenced on 5th
September 2012.
Since December 1992, the
East of Sha Chau area has been the site of a series of dredged contaminated mud
pits (CMPs) designed to provide confined marine disposal capacity for contaminated
mud arising from the HKSAR¡¦s dredging and reclamation projects. The latest group of pits, CMP Va, b, c
& d began receiving contaminated mud from construction projects on 10
February 2012. CMP Va is presently
in operation for backfilling of contaminated sediments.
Capacity to dispose of
contaminated mud is currently predicted to be exhausted in 2015 with the
completion of backfilling of CMP Vd at East of Sha Chau (ESC). When CMP Vd is full, a new
environmentally acceptable disposal capacity for essential arisings will be
required. The environmental
acceptability of the construction and operation of the CMPs at the South of the
Brothers (the Project) had been confirmed by the findings of the associated EIA
study completed in 2005 under Agreement No. CE
12/2002(EP) ([1]). The Director of Environmental Protection
(DEP) approved the respective EIA report of this Agreement under the EIAO in
September 2005 (EIA Register No.: AEIAR-089/2005). A detailed EIA Review (the Review) was
carried out under Agreement No. FM 2/2009 ([2]) to re-confirm the relevance
of the findings of the approved EIA report with respect to the up-to-date
information of other concurrent projects in the vicinity or any updated
requirements/guidelines and to recommend on the environmental viability of the
proposed the South of The Brothers (SB) CMPs.
The Review concluded that
relevant findings and recommendations of the approved EIA report in relation to
the SB CMPs are still valid. An
information note advising members of the Advisory Council on the Environment (ACE)
about the Review outcome was circulated in August 2010 with no further comments
received.
An Environmental Permit (EP-427/2011) for Dredging, Management
and Capping of Contaminated Sediment Disposal Facility to the South of The
Brothers (hereafter referred as ¡§the Project¡¨) was issued by the Environmental
Protection Department (EPD) to the CEDD, the Permit Holder, on 3 November 2011
and varied on 23 December 2011 (EP-427/2011/A).
Under the requirements of Condition 4 of the EP (EP-427/2011/A), an EM&A programme as
set out in the Environmental Monitoring
and Audit Manual (EM&A Manual) is required to be implemented during
construction and operational phases of the SB CMPs. In accordance with the EM&A Manual, baseline monitoring of
water quality is required to be undertaken prior to dredging activities to form
the SB CMPs.
The purpose of this Baseline Monitoring Report is to present
baseline marine water quality at the designated monitoring locations in the
Project and reference areas prior to the commencement of marine dredging
works. These levels will be used as
the basis for compliance monitoring during dredging, backfilling and capping activities
at the SB CMPs. This report presents
the monitoring requirements, methodologies and results of the baseline marine
water quality measurements in accordance with the EM&A Manual.
After this introductory
section, the remainder of the report is structured as follows:
Section 2 : Baseline
Water Quality Monitoring Methodology
Summarises
the water quality monitoring parameters, monitoring programme, monitoring
methodology, monitoring frequency and monitoring locations.
Section
3 : Baseline Water Quality Monitoring
Results
Presents the
monitoring results and establishes the Action and Limit Levels in accordance
with the EM&A Manual.
Section
4 : Conclusions
Concludes
the representativeness of the baseline monitoring results and observations for
the Project.
The following Section provides details of methodology used in the
baseline monitoring of water quality prior to the commencement of marine dredging works for
the Project.
In accordance with the EM&A Manual, water quality sampling
was undertaken at monitoring stations in the vicinity of the new facility at the South of The Brothers
and in reference areas (EPD Water Quality Monitoring Stations NM1, 2, 3, 5 and
6) prior to the commencement of marine dredging works. Locations of the baseline monitoring
stations are shown in Figure 2.1. Co-ordinates of these monitoring
stations are listed in Table 2.1.
Table 2.1 Coordinates of Water
Quality Monitoring Stations for Baseline Water Quality Monitoring
Monitoring
Stations |
Easting |
Northing |
Far
Field Stations |
|
|
SB-WFA |
805787 |
827951 |
SB-WFB |
806066 |
816537 |
Mid
Field Stations |
|
|
SB-WMA |
813001 |
821559 |
SB-WMB |
818386 |
822120 |
Near
Field Stations |
|
|
SB-WNAA |
814847 |
820043 |
SB-WNAB |
816197 |
819911 |
SB-WNBA |
813999 |
819207 |
SB-WNBB |
815505 |
819019 |
Reference
Stations |
|
|
NM1 |
820256 |
823214 |
NM2 |
816015 |
823686 |
NM3 |
812527 |
824049 |
NM5 |
807707 |
827244 |
NM6 |
807584 |
820286 |
Sensitive
Receiver Stations |
|
|
MW1 |
823604 |
823654 |
THB1 |
814514 |
817932 |
THB2 |
815873 |
818035 |
WSR45C |
817431 |
820211 |
WSR46 |
813880 |
820973 |
Note: Coordinates are based
on
Baseline water quality
monitoring was conducted in accordance with the requirements stated in the EM&A Manual, which are presented below.
Parameters measured in situ were:
¡P
Dissolved
Oxygen (mg L-1);
¡P
Salinity
(ppt);
¡P
pH;
¡P
Turbidity
(NTU);
¡P
Temperature
(¢XC); and
¡P
Current
Velocity and Direction (ms-1).
Parameters measured in the
laboratory were:
¡P
Suspended
Solids (SS) (mg L-1);
¡P
Ammonia
(mg L-1);
¡P
Total
Inorganic Nitrogen (TIN mg L-1);
¡P
5-Day
Biochemical Oxygen Demand (BOD5);
¡P
Cadmium
(mg L-1);
¡P
Chromium
(mg L-1);
¡P
Copper
(mg L-1);
¡P
Lead
(mg L-1);
¡P
Mercury
(mg L-1);
¡P
Nickel
(mg L-1);
¡P
Silver
(mg L-1);
¡P
Zinc
(mg L-1); and
¡P
Arsenic
(mg L-1).
In addition to the water
quality parameters, other relevant data were measured and recorded in Water
Quality Monitoring Logs, including the location of the sampling stations, water
depth, time, weather conditions, sea conditions, tidal stage, special phenomena
and work activities undertaken around the monitoring and works area that may
influence the monitoring results.
Baseline water quality monitoring should be carried
out for four weeks, with the frequency of three days per week. The interval between two sets of
monitoring was not less than 36 hours.
In situ measurements and water samples were taken during mid-flood and mid-ebb tidal stages on each
sampling occasion.
Positioning Device
A Global Positioning System (GPS) was used (C-Nav globally corrected DGPS, GPS 84 datum) during
monitoring to ensure the accurate recording of the position of the monitoring
vessel before taking measurements. The
instrument calibration was checked by recording a measured position at a
previously coordinated location on shore.
Electronic data logging
device
A data logging device
capable of storing in situ measurement
data was used. The device was able
to read and store the output from all electronic meters used for this project
and recorded time and location as measured by the GPS.
The instrument was a portable, weatherproof
multi-parameter measuring instrument (YSI 6820) complete with cables,
multi-probe sensor, comprehensive operation manuals, and was operable from a DC
power source. It was capable of
measuring:
¡P turbidity levels between 0-1000 NTU (response of
the sensor was checked with certified standard turbidity solutions before the
start of measurement);
¡P pH of 0 to 14 units with a resolution of 0.01 unit;
¡P dissolved oxygen levels in the range of 0 ¡V 50 mg L-1;
and 0-500% saturation;
¡P temperature of -5 to 45 ¢XC; and,
¡P salinity in the range of 0-40 ppt
(checked with 30 ppt Salinity solutions before the
start of the measurement).
An echo sounder mounted to the hull of the survey
vessel was used to measure water depth.
Water samples for suspended solids measurement were
collected by the use of a multi-bottle water sampling
system (General Oceanics Inc., Rosette Sampler ROS02),
consisting of PVC bottles of more than two litres,
which could be effectively sealed with cups at both ends. The water sampler had a positive
latching system to keep it open and prevent premature closure until released by
a messenger when the sampler was at the selected water depth.
Water quality sampling was
undertaken within a 4-hour window of 2 hours before or after mid-flood and
mid-ebb tides. Tidal range for
flood and ebb tides was not less than 0.5 m for capturing representative tides.
Reference was made to the predicted tides at Chek Lap Kok, which is the tidal station nearest to the
Project site, published on the website of Hong Kong Observatory ([3]). Based
on the predicted water levels at Chek Lap Kok, the
baseline water quality monitoring was conducted between 26 July and 23 August 2012,
following the schedule presented in Annex A. It should be noted that on 16 August
2012, monitoring was cancelled due to adverse weather conditions caused by the
typhoon Kai Tak which led to the issue of Typhoon
Signal No. 8 by the Hong Kong Observatory during the survey time. As a result, baseline monitoring was
undertaken over a period of five (5) weeks during which twelve (12) sampling
events were conducted.
Triplicate samples were collected from each of the
monitoring events for in situ measurements and laboratory analysis.
Each station was sampled and measurements were
taken at three depths, 1 m below the sea surface, mid depth and 1 m above the
sea bed. Where the water depth was
less than 6 m, the mid-depth station was omitted. For stations that were less than 3 m in
depth, only the mid depth sample was taken.
The multi-parameter measuring instruments (YSI
6820) were checked and calibrated by an HOKLAS accredited laboratory before use
(see calibration reports in Annex B). Onsite calibration was also carried out
to check the responses of sensors and electrodes using certified standard
solutions before each use.
Sufficient stocks of spare parts were maintained for replacements when
necessary, and backup monitoring equipment was made available.
Water samples were collected in high density
polythene bottles, packed in ice (cooled to 4¢X C without being frozen), and
delivered to HOKLAS accredited laboratory as soon as possible after collection for immediate analysis.
All laboratory work was carried out by HOKLAS
accredited laboratory. Water
samples were collected at the monitoring and reference stations for carrying
out the laboratory determinations.
The determination work started within the next working day after
collection of the water samples.
For laboratory analysis, the Quality Assurance /
Quality Control (QA/QC) details were in accordance with requirements of HOKLAS
or another internationally accredited scheme (details refer to Annex C).
This Section presents the
results of the baseline monitoring of water quality for the Project.
Monitoring data and
graphical presentations are summarised in Annex D.
No major activities
influencing the water quality were identified during the monitoring period.
The Action and Limit Levels
for DO, turbidity and SS were set in the EM&A
Manual and the proposed Action and Limit Levels were determined as shown in
Table 3.1.
The Action and Limit Levels
of DO, turbidity and SS are derived from the baseline monitoring data for all
stations, and the results are presented in Table
3.2.
Table 3.1 Determination
of Action and Limit Level of Water Quality for Dredging, Backfilling and
Capping Activities
Parameter |
Action
Level |
Limit
Level |
Dissolved
Oxygen |
|
|
Surface and Middle Depth Averaged |
The average of the impact, WSR
45C and WSR 46 station
readings are < 5%ile of baseline data and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
The average of the impact, WSR
45C and WSR 46
station readings are < 4 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
Bottom |
The average of the impact, WSR
45C and WSR 46 station
readings are < 5%ile of baseline data and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
The average of the impact, WSR
45C and WSR 46
station readings are < 2 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
Suspended
Solids |
|
|
Depth Averaged |
The average of the impact, WSR
45C and WSR 46
station readings are > 95%ile of baseline data and 120% or more of the reference
stations SS (at the same tide of the same day) |
The average of the impact, WSR
45C and WSR 46
station readings are > 99%ile of baseline data and 130% or more of the reference
stations SS (at the same tide of the same day) |
Turbidity |
|
|
Depth Averaged |
The average of the impact, WSR
45C and WSR 46
station readings are > 95%ile of baseline data and 120% or more of the reference
stations turbidity (at the same tide of the same day) |
The average of the impact, WSR
45C and WSR 46
station readings are > 99% of baseline data and 130% or more of the reference
stations turbidity (at the same tide of the same day) |
Table 3.2 Proposed
Action and Limit Levels of Water Quality for Dredging, Backfilling and Capping
Activities
Parameter |
Action
Level |
Limit
Level |
Dissolved
Oxygen (DO) (1) |
Surface and Mid-depth (2) |
Surface and Mid-depth (2) |
|
The average of the impact, WSR
45C and WSR 46 station
readings are < 5%-ile of baseline data for
surface and middle layer = 4.32 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
The average of the impact, WSR
45C and WSR 46
station readings are < 4 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
|
|
|
|
Bottom |
Bottom |
|
The average of the impact, WSR
45C and WSR 46 station
readings are < 5%-ile of baseline data for
bottom layers = 3.12 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
The average of the impact station, WSR
45C and WSR 46
readings are < 2 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
|
|
|
Depth-averaged
Suspended Solids (SS) (3) (4) |
The average of the impact, WSR
45C and WSR 46
station readings are > 95%-ile
of baseline data for depth average = 21.60 mg L-1 and |
The average of the impact, WSR
45C and WSR 46
station readings are > 99%-ile
of baseline data for depth average = 40.10 mg L-1 and |
|
120%
of control station's SS at the same tide of the same day |
130%
of control station's SS at the same tide of the same day |
|
|
|
Depth-averaged
Turbidity (Tby) (3) (4) |
The average of the impact, WSR
45C and WSR 46
station readings are > 95%-ile
of baseline data = 25.04 NTU and |
The average of the impact, WSR
45C and WSR 46
station readings are > 99%-ile
of baseline data = 56.30 NTU and |
|
120%
of control station's Tby at the same tide of the same day |
130%
of control station's Tby at the same tide of the same day |
|
|
|
Notes: (1) For
DO, non-compliance of the water quality limits occurs when monitoring result
is lower than the limits. (2) The
Action and Limit Levels for DO for Surface & Middle layers were
calculated from the combined pool of baseline surface layer data and baseline
middle layer data. (3) ¡§Depth-averaged¡¨
is calculated by taking the arithmetic means of reading of all three depths. (4) For
turbidity and SS, non-compliance of the water quality limits occurs when
monitoring result is higher than the limits. |
Baseline water quality
monitoring was conducted between 26 July and 23 August 2012 at eighteen
designated monitoring stations established for the Project. The monitoring was carried out 3 days
per week, at mid-flood and mid-ebb tides, at three depths (surface, middle and
bottom), for 5 weeks prior to the commencement of dredging works in accordance
with the Environmental Monitoring and Audit Manual for the Project. No major activities were noted during
baseline monitoring. Water quality
monitoring results are, therefore, representative of the baseline conditions
for the Project.
Results have been used to
determine Action and Limit Levels for the dissolved oxygen, suspended solids
and turbidity for impact monitoring to be conducted during dredging,
backfilling and capping activities of the two seabed pits for the new facility
at the South of The Brothers. The proposed Action and Limit Levels for DO, SS
and Turbidity listed in Table 4.1
below will be adopted for impact monitoring during dredging, backfilling and
capping activities of the Project.
Table 4.1 Proposed
Action and Limit Levels of Water Quality for Dredging, Backfilling and Capping
Activities
Parameter |
Action
Level |
Limit
Level |
Dissolved
Oxygen (DO) (1) |
Surface and Mid-depth (2) |
Surface and Mid-depth (2) |
|
The average of the impact, WSR
45C and WSR 46 station
readings are < 5%-ile of baseline data for
surface and middle layer = 4.32 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
The average of the impact, WSR
45C and WSR 46
station readings are < 4 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
|
|
|
|
Bottom |
Bottom |
|
The average of the impact, WSR
45C and WSR 46 station
readings are < 5%-ile of baseline data for
bottom layers = 3.12 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
The average of the impact station, WSR
45C and WSR 46
readings are < 2 mg L-1 and Significantly less than the
reference stations mean DO (at the same tide of the same day) |
|
|
|
Depth-averaged
Suspended Solids (SS) (3) (4) |
The average of the impact, WSR
45C and WSR 46
station readings are > 95%-ile
of baseline data for depth average = 21.60 mg L-1 and |
The average of the impact, WSR
45C and WSR 46
station readings are > 99%-ile
of baseline data for depth average = 40.10 mg L-1 and |
|
120%
of control station's SS at the same tide of the same day |
130%
of control station's SS at the same tide of the same day |
|
|
|
Depth-averaged
Turbidity (Tby) (3) (4) |
The average of the impact, WSR
45C and WSR 46
station readings are > 95%-ile
of baseline data = 25.04 NTU and |
The average of the impact, WSR
45C and WSR 46
station readings are > 99%-ile
of baseline data = 56.30 NTU and |
|
120%
of control station's Tby at the same tide of the
same day |
130%
of control station's Tby at the same tide of the same
day |
|
|
|
Notes: (1) For
DO, non-compliance of the water quality limits occurs when monitoring result
is lower than the limits. (2) The
Action and Limit Levels for DO for Surface & Middle layers were
calculated from the combined pool of baseline surface layer data and baseline
middle layer data. (3) ¡§Depth-averaged¡¨
is calculated by taking the arithmetic means of reading of all three depths. (4) For
turbidity and SS, non-compliance of the water quality limits occurs when
monitoring result is higher than the limits. |
([1])
Detailed Site Selection Study for a
Proposed Contaminated Mud Disposal Facility within the Airport East/ East of
Sha Chau Area (Agreement No. CE 12/2002(EP))
[2] Contaminated
Sediment Disposal Facility at South of Brothers (Agreement No. FM 2/2009)